DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Claim Interpretation
The claims have been interpreted in accordance with the broadest reasonable interpretation consistent with the specification.
Claims 1 and 9
With respect to the scope of "a notification circuit structured to provide a notification indicating that the second sensor is faulty," Applicant's specification at paragraph [0038] states that the processor "can include a notification circuit," and paragraph [0037] states that the display to which the notification is provided may be a data port on the engine or in a vehicle associated with the engine. Accordingly, circuitry within an engine control unit that generates and outputs a fault or diagnosis signal identifying a particular sensor as failed is within the broadest reasonable interpretation of this limitation; an operator-visible malfunction indicator lamp is not required.
With respect to "a first signal indicative of an upstream air-fuel equivalence ratio" and "a second signal indicative of a downstream air-fuel equivalence ratio," Applicant's specification at paragraph [0025] states that the exhaust gas oxygen sensors "may be heated or unheated, or of a narrow-band (i.e., switching) or wide-band type of sensor." Accordingly, the output of a narrow-band switching-type oxygen sensor, which indicates whether the air-fuel equivalence ratio (lambda) is greater than or less than one, is a signal indicative of an air-fuel equivalence ratio under the broadest reasonable interpretation.
With respect to "predict an expected second signal based at least in part on the desired first signal," the term "predict" is given its plain meaning and encompasses determining in advance, by calibration, experiment, or computation, the value that the second signal should take under the commanded upstream condition. Nothing in claim 1 requires a real-time physical model or an on-line state observer. This interpretation is consistent with Applicant's specification at paragraphs [0065] and [0068], which describe the predicted second lambda as a value the controller "develops" from the desired first lambda and give discrete calibrated example values.
Claims 2 and 10
With respect to "wherein providing the control signal causes more fuel to be injected into the engine" recited in claim 2, the comparative term "more" is not referenced to any stated baseline in the claim. Under the broadest reasonable interpretation, this limitation is satisfied where provision of the control signal results in an increase in the quantity of fuel injected relative to the quantity being injected immediately prior to provision of that control signal.
Claim 6
With respect to "wherein the fault signal is only provided during a dithering mode" recited in claim 6, Applicant's specification at paragraph [0027] states that "[d]ithering occurs during normal operation of the engine when fuel is being provided" and that "[i]n the dithering condition, the air:fuel mixture of the exhaust gas will alternate between rich and lean." A dithering mode is accordingly interpreted as a mode of engine operation in which fuel is provided to the engine and the air-fuel ratio of the exhaust gas alternates between rich and lean. The term "only" is interpreted as requiring that the processing circuit not provide the fault signal outside of that mode.
Claim 7
With respect to "maintained within a predefined value" recited in claim 7, the phrase is imprecise in that a value is not a range within which a quantity can be maintained. Read in light of the specification, which describes the controller continuing to monitor until the first lambda equals the desired first lambda "and has reached steady state" (Spec., [0066]), the limitation is interpreted as requiring that the second signal differential be determined when the upstream air-fuel equivalence ratio indicated by the first signal has settled to and is being held at a predefined value. Applicant may wish to clarify this limitation.
Claim 14
With respect to "with limited fuel" recited in claim 14, the term is interpreted as encompassing operation in which the fuel supplied to the engine is restricted, including operation in which the feed of fuel is stopped entirely. This interpretation is consistent with the claim itself, which recites the limitation with respect to "the fuel cut or lean run signal," and with Applicant's specification at paragraph [0069], which describes operating the engine in a fuel cut condition for a predetermined fuel cut time intended to provide the catalyst adequate time to fully oxidize or adsorb a full storage capacity of oxygen.
Claim Rejections - 35 USC § 112
The following is a quotation of 35 U.S.C. 112(b):
(b) CONCLUSION.—The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the inventor or a joint inventor regards as the invention.
The following is a quotation of 35 U.S.C. 112 (pre-AIA ), second paragraph:
The specification shall conclude with one or more claims particularly pointing out and distinctly claiming the subject matter which the applicant regards as his invention.
Claims 4, 5, and 12 rejected under 35 U.S.C. 112(b) or 35 U.S.C. 112 (pre-AIA ), second paragraph, as being indefinite for failing to particularly point out and distinctly claim the subject matter which the inventor or a joint inventor (or for applications subject to pre-AIA 35 U.S.C. 112, the applicant), regards as the invention.
Claim 4 recites that "providing the control signal causes more fuel to be injected into the engine, and the desired first signal is indicative of an air-fuel equivalence ratio of greater than one." These two requirements are in conflict. The air-fuel equivalence ratio, lambda, is the ratio of the actual induced air mass to the theoretical air requirement for the fuel injected. Increasing the quantity of fuel injected for a given induced air mass therefore decreases lambda toward and below one, and cannot produce a desired first signal indicative of an air-fuel equivalence ratio greater than one. It is accordingly unclear what apparatus is encompassed by claim 4. The specification does not resolve the conflict. The specification describes providing a rich mixture where the second sensor is suspected of being stuck lean and a lean mixture where the second sensor is suspected of being stuck rich (PGPUB [0031]), and describes operation instructions that cause the engine to "inject more or less fuel" (PGPUB [0037]). No embodiment is described in which a control signal causing more fuel to be injected produces a desired upstream air-fuel equivalence ratio greater than one. Claim 2, which recites the same first clause, recites a desired first signal indicative of an air-fuel equivalence ratio of less than one, consistent with the specification.
Claim 5 is rejected as depending from an indefinite claim.
In view of the indefiniteness, and for the purpose of applying prior art, the limitation "providing the control signal causes more fuel to be injected into the engine" is interpreted as requiring that providing the control signal changes the quantity of fuel injected into the engine.
Appropriate correction is requested. It is suggested that claim 4 be amended to recite that providing the control signal causes less fuel to be injected into the engine.
Claim 12 recites that "providing the control signal causes more fuel to be injected into the engine, and wherein the desired first signal is indicative of an air-fuel equivalence ratio of greater than one." These requirements conflict, for the reasons set forth with respect to claim 4 above. The air-fuel equivalence ratio, lambda, is the ratio of the actual induced air mass to the theoretical air requirement for the fuel injected; increasing the fuel injected for a given induced air mass therefore decreases lambda toward and below one, and cannot produce a desired first signal indicative of an air-fuel equivalence ratio greater than one. The specification does not resolve the conflict, describing a rich mixture where the second sensor is suspected stuck lean and a lean mixture where it is suspected stuck rich (PGPUB [0031]), and describing instructions to "inject more or less fuel" (PGPUB [0037]), but describing no embodiment in which more fuel produces a desired upstream lambda greater than one. Claim 10, which recites the same first clause, recites a desired first signal indicative of lambda less than one.
Appropriate correction is requested. It is suggested that claim 12 be amended to recite that providing the control signal causes less fuel to be injected into the engine.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
Claim(s) 1-12 is/are rejected under 35 U.S.C. 103 as being unpatentable over Yook (US 2003/0225505 A1) in view of Hayashita et al. (US 2016/0131064 A1).
Regarding claim 1, Yook discloses an apparatus comprising:
a processing circuit (Yook discloses an engine control unit (ECU) 30 that includes a microprocessor, a memory, and other necessary hardware and software components as will be understood by persons of ordinary skill in the art to permit the ECU 30 to communicate with sensors and execute a diagnostic method (Yook, [0014]; FIG. 1).) structured to:
receive a first signal indicative of an upstream air-fuel equivalence ratio from a first sensor positioned upstream of an intake of a catalyst (Yook discloses that a front oxygen sensor 20 is located upstream of a catalytic converter 3 disposed in an exhaust pipe 1, that the front oxygen sensor generates a voltage signal proportional to the difference in oxygen content between the exhaust gas and ambient air, and that the ECU 30 receives that signal (Yook, [0014]–[0015]), Yook further expressly correlating the sensor outputs to lambda, which Yook defines as the excess air factor indicating the deviation of the actual air/fuel ratio from the theoretically required ratio (Yook, [0023]; see also [0025]–[0026]).);
receive a second signal indicative of a downstream air-fuel equivalence ratio from a second sensor positioned downstream of the intake of the catalyst (Yook discloses that a rear oxygen sensor 21 is located downstream of the catalytic converter 3, that the rear oxygen sensor likewise generates a voltage signal proportional to the difference in oxygen content between the exhaust gas and ambient air, and that the ECU 30 receives that signal (Yook, [0014]–[0015]), the rear oxygen sensor output being correlated to a rich or lean air/fuel mixture relative to lambda equal to one (Yook, [0025]–[0026]).);
provide a control signal to an engine to produce a desired first signal (Yook discloses that at step S70 the ECU 30 controls the injected fuel quantity, by way of injection command signals provided to a fuel injector 40, such that the air/fuel ratio becomes a predetermined rich air/fuel ratio of 0.85 lambda for a predetermined rich control period (Yook, [0014], [0023]), the desired first signal being the front oxygen sensor output that the commanded rich condition is expected to produce, namely an output greater than the first threshold value of 0.5 V (Yook, [0024], [0026]–[0027]).);
predict an expected second signal based at least in part on the desired first signal (Yook discloses reasoning directly from the commanded rich condition to the value the rear oxygen sensor should produce, stating that when the air/fuel ratio is richer than a stoichiometric air/fuel ratio, that is, when lambda is less than one, the output voltage of the front oxygen sensor 20 should be greater than 0.5 V and the output voltage of the rear oxygen sensor 21 should also be greater than 0.45 V (Yook, [0026]), and reiterating that if the air/fuel mixture is regulated to be rich for the predetermined period, the output value of the front oxygen sensor should be greater than 0.5 V and the output value of the rear oxygen sensor should also be greater than 0.45 V (Yook, [0027]), such that the value of 0.45 V constitutes an expected second signal predicted from the desired first signal.);
compare the first signal to the desired first signal (Yook discloses that at step S90 the ECU 30 determines whether the output value of the front oxygen sensor 20 is greater than a first threshold value for determining a rich air/fuel ratio, the first threshold value preferably being set as 0.5 V, and that if the output value of the front oxygen sensor is greater than the first threshold value the ECU 30 determines that the air/fuel mixture is rich (Yook, [0024]–[0025]).);
determine a second signal differential between the second signal and the expected second signal when the first signal is equal to the desired first signal (Yook discloses that at step S80 the ECU 30 simultaneously detects the output value of the front oxygen sensor 20 and the output value of the rear oxygen sensor 21 at a point after the rich control of step S70, and that at step S90 the ECU 30 evaluates the rear oxygen sensor output against the expected value of 0.45 V, the failure determination being expressly conditioned upon the front oxygen sensor output having reached its expected rich value of greater than 0.5 V, such that the evaluation of the second signal against its expected value is performed and acted upon only when the first signal has attained the desired first signal (Yook, [0024], [0027]); Yook thus teaches evaluating the second signal against the expected second signal under the recited condition, and see the discussion of Hayashita below with respect to performing that evaluation as a differential.);
and provide a fault signal in response to the second signal differential exceeding a threshold differential (Yook discloses that at step S90, if it is determined that the output voltage of the front oxygen sensor 20 is greater than 0.5 V and the output voltage of the rear oxygen sensor 21 is less than 0.45 V for the predetermined period, it is concluded that the rear oxygen sensor 21 has a failure, and the ECU 30 then generates a corresponding fault signal at step S92 (Yook, [0006], [0027]); Yook thus teaches providing a fault signal in response to the second signal deviating from the expected second signal, and see the discussion of Hayashita below with respect to the recited threshold differential.); and
a notification circuit structured to provide a notification indicating that the second sensor is faulty in response to receiving the fault signal (Yook discloses that the ECU 30 generates a fault diagnosis signal that specifically identifies the rear oxygen sensor 21 as having failed (Yook, [0005]–[0006], [0020], [0027]), as distinguished from the corresponding diagnosis signal generated at step S94 when the ECU 30 determines that the rear oxygen sensor 21 normally operates (Yook, [0027]), Yook expressly situating this diagnostic reporting within the OBD-II on-board diagnostic framework, which requires a device for diagnosing a malfunction of an emissions-related diagnosing device (Yook, [0002]–[0003]); under the broadest reasonable interpretation set forth above, and in view of Applicant's specification at paragraphs [0037]–[0038], this circuitry constitutes a notification circuit that provides a notification indicating that the second sensor is faulty.).
However, Yook does not expressly disclose expressing the evaluation of the second signal against the expected second signal as a second signal differential, or providing the fault signal in response to that differential exceeding a threshold differential, Yook instead performing a one-sided comparison of the rear oxygen sensor output against the expected value of 0.45 V.
Hayashita, in the same field of endeavor as Yook and as the claimed invention, namely on-board diagnosis of an exhaust gas sensor arranged downstream of a catalyst, teaches determining a second signal differential between the second signal and the expected second signal when the first signal is equal to the desired first signal, and providing a fault signal in response to that differential exceeding a threshold differential. Specifically: Hayashita teaches an ECU 31 that diagnoses abnormality of a downstream side air-fuel ratio sensor 41 arranged downstream of an oxygen-storing three-way exhaust purification catalyst 20, in an engine further having an upstream side air-fuel ratio sensor 40 arranged upstream thereof (Hayashita, [0041]–[0044]); that fuel injection is feedback-controlled based on the output of the upstream side sensor 40 so that the air-fuel ratio becomes a target air-fuel ratio, which is set and maintained constant in order to conduct the diagnosis, whereby the air-fuel ratio of the exhaust gas circulating around the downstream side sensor 41 is likewise maintained at that target value (Hayashita, [0058], [0129]–[0131], [0134]; claim 15); that the output which a normal downstream side sensor would produce under that known condition is detected or calculated in advance experimentally or by computation as a normal value (Hayashita, [0086], [0138]); that sampling is deferred until the predetermined time Δt0 required for the output air-fuel ratio to converge following the change of the target air-fuel ratio has elapsed (Hayashita, [0135], [0148]–[0149]); and that where the difference between the detected value of the output current of the downstream side sensor 41 and the corresponding normal value is a predetermined reference value or more, it is judged that a deviation has occurred at the downstream side air-fuel ratio sensor 41 (Hayashita, [0106], [0139]; claim 5).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the rear oxygen sensor evaluation performed at steps S90 and S92 of Yook to determine the difference between the detected rear oxygen sensor signal and the expected rear oxygen sensor value, and to provide the fault signal in response to that difference being a predetermined reference value or more, as taught by Hayashita, in order to detect a deviation of the downstream sensor even where that deviation is slight, which Hayashita teaches is necessary because a deviation in sensor output at the stoichiometric air-fuel ratio corrupts the air-fuel ratio control (Hayashita, [0008]–[0009], [0021], [0068]–[0069]). One of ordinary skill in the art would have recognized that in Yook a rear oxygen sensor exhibiting a moderate rich-side offset would nonetheless still produce an output exceeding 0.45 V and would therefore be passed as operating normally at step S90 (Yook, [0027]), leaving unmet the OBD-II diagnostic objective that Yook identifies as the purpose of the invention (Yook, [0002]–[0003]). The modification is the use of a known technique (Hayashita, [0106], [0139]) to improve a comparable diagnostic in the same way (see MPEP 2143(I)(C)), and one of ordinary skill would have had a reasonable expectation of success because it alters only the arithmetic form of a comparison that the same engine control unit already performs on the same sensor signal at the same point in the same diagnostic routine (Yook, [0026]–[0027]), the selection of a particular non-zero reference value being a matter of routine calibration. The rejection relies on Hayashita's teaching of a difference-versus-reference-value determination and does not require bodily incorporation of Hayashita's applied voltage control device 60 or limit current type sensor structure into Yook. See MPEP 2145(III).
Regarding claim 2, Yook in view of Hayashita teaches the apparatus of claim 1 for the reasons set forth above, including the rationale for combining Yook and Hayashita. Yook further discloses: wherein providing the control signal causes more fuel to be injected into the engine (Yook discloses that a fuel injector 40 injects fuel according to an injection command signal from the ECU 30 (Yook, [0014]), and that at step S70 the ECU 30 controls the injected fuel quantity so that the air/fuel ratio becomes a predetermined air/fuel ratio richer than stoichiometric, set as 0.85 lambda (Yook, [0004], [0023]); because Yook defines lambda as the ratio of actual induced air mass to theoretical air requirement (Yook, [0023]), commanding 0.85 lambda requires increasing the injected fuel quantity for the air mass then induced, and Yook further discloses that the diagnostic is entered only where fuel flow has been reduced and maintained reduced (Yook, [0017], [0020]).), and the desired first signal is indicative of an air-fuel equivalence ratio of less than one (Yook discloses that 0.85 lambda is richer than a stoichiometric air/fuel ratio of lambda equal to one (Yook, [0023]), and that when lambda is less than one the output voltage of the front oxygen sensor 20 should be greater than 0.5 V (Yook, [0026]–[0027]); the desired first signal identified with respect to claim 1, namely a front oxygen sensor output greater than 0.5 V, is therefore indicative of an air-fuel equivalence ratio of less than one.).
Regarding claim 3, Yook in view of Hayashita teaches the apparatus of claim 2 for the reasons set forth above, including the rationale for combining Yook and Hayashita. Yook further discloses: wherein the expected second signal is indicative of an air-fuel equivalence ratio of less than one (Yook discloses that when the air/fuel ratio is richer than a stoichiometric air/fuel ratio, that is, when lambda is less than one, the output voltage of the rear oxygen sensor 21 should be greater than 0.45 V (Yook, [0026]; see also [0027]), and that if the output value of the rear oxygen sensor is greater than the second threshold value of 0.45 V, the ECU 30 determines that the air/fuel mixture is rich (Yook, [0024]–[0025]); the expected second signal identified with respect to claim 1, namely a rear oxygen sensor output greater than 0.45 V, is therefore indicative of an air-fuel equivalence ratio of less than one.).
Regarding claim 4, Yook in view of Hayashita teaches the apparatus of claim 1 for the reasons set forth above, including the rationale for combining Yook and Hayashita, and applying the interpretation of "causes more fuel to be injected into the engine" set forth in the 35 U.S.C. 112(b) rejection above. See MPEP 2173.06(I). Yook does not disclose a control signal producing a desired first signal indicative of an air-fuel equivalence ratio greater than one, Yook commanding a rich air/fuel ratio of 0.85 lambda (Yook, [0023]). Hayashita teaches: wherein providing the control signal causes a change in fuel to be injected into the engine, and the desired first signal is indicative of an air-fuel equivalence ratio of greater than one (Hayashita teaches that the ECU 31 provides injection signals to the fuel injectors 11 through drive circuits 45 (Hayashita, [0039], [0043]), that the fuel injection quantity is feedback-controlled based on the output of the upstream side sensor 40 so that the air-fuel ratio becomes the target air-fuel ratio (Hayashita, [0058], [0129]), and that the target air-fuel ratio is set to a lean set air-fuel ratio AFTlean, for example 15, leaner than the stoichiometric air-fuel ratio of 14.6, whereupon the air-fuel ratio flowing into the catalyst 20 becomes a lean air-fuel ratio (Hayashita, [0060], [0063]); Hayashita further teaches that the target air-fuel ratio maintained constant for the diagnosis may be an air-fuel ratio other than stoichiometric (Hayashita, [0141]). Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify Yook such that the control signal commands a target air-fuel ratio leaner than stoichiometric, producing a desired first signal indicative of an air-fuel equivalence ratio greater than one, as taught by Hayashita, in order to detect a rear oxygen sensor that is stuck rich. Yook's diagnostic commands a rich condition and detects a rear sensor that fails to indicate rich, and therefore detects only a sensor stuck lean (Yook, [0027]); one of ordinary skill would have recognized that the complementary fault is not detected by that command direction and would have been motivated to command the opposite condition to detect it, Hayashita teaching that a downstream sensor erroneously indicating rich defeats the air-fuel ratio control and that the downstream sensor must be able to detect whether the exhaust flowing out of the catalyst is rich or lean (Hayashita, [0068]). One of ordinary skill would have had a reasonable expectation of success, commanding a lean rather than rich target requiring no structural change to Yook, whose ECU 30 and fuel injector 40 are already configured to set the air/fuel ratio to a commanded value (Yook, [0014], [0023]).).
Regarding claim 5, Yook in view of Hayashita teaches the apparatus of claim 4 for the reasons set forth above, including the rationale for combining Yook and Hayashita and the rationale for commanding a target air-fuel ratio leaner than stoichiometric. Hayashita further teaches: wherein the expected second signal is indicative of an air-fuel equivalence ratio of greater than one (Hayashita teaches that where the output air-fuel ratio of the upstream side sensor 40 is feedback-controlled to become the target air-fuel ratio, the air-fuel ratio of the exhaust gas circulating around the downstream side air-fuel ratio sensor 41 is maintained constant at that target air-fuel ratio, which target may be an air-fuel ratio other than the stoichiometric air-fuel ratio (Hayashita, [0129]–[0131], [0141]); Hayashita further teaches that upon fuel cut control the oxygen storage amount of the catalyst 20 reaches its maximum storable amount, whereupon atmospheric gas flows out of the catalyst 20 and the output air-fuel ratio of the downstream side sensor 41 changes to a lean air-fuel ratio of extremely large lean degree corresponding to the atmospheric gas (Hayashita, [0093]); and that for such a commanded lean condition the output which a normal downstream side sensor would produce is detected or calculated in advance experimentally or by computation as a normal value against which the detected value is compared (Hayashita, [0104], [0106]); the expected second signal for a commanded lean condition is therefore indicative of an air-fuel equivalence ratio of greater than one. Further, one of ordinary skill in the art would have recognized that where the control signal commands a lean condition as set forth with respect to claim 4, the expected downstream air-fuel equivalence ratio is necessarily greater than one once the oxygen storage capacity of the catalyst is exceeded, Yook's rear oxygen sensor being determined to indicate a lean mixture where its output is less than the second threshold value of 0.45 V (Yook, [0025]–[0026]), such that the recited expected second signal is the predictable result of the modification set forth with respect to claim 4.).
Regarding claim 6, Yook in view of Hayashita teaches the apparatus of claim 1 for the reasons set forth above, including the rationale for combining Yook and Hayashita. Yook does not disclose that the fault signal is only provided during a dithering mode, Yook conducting the diagnostic while a steady rich air/fuel ratio of 0.85 lambda is commanded (Yook, [0023], [0027]). Hayashita teaches: wherein the fault signal is only provided during a dithering mode (Hayashita teaches normal engine operation in which fuel is provided and the target air-fuel ratio is alternately changed between a rich set air-fuel ratio AFTrich of 14.4 and a lean set air-fuel ratio AFTlean of 15, such that the air-fuel ratio of the exhaust gas flowing into the catalyst 20 alternates between rich and lean (Hayashita, [0059]–[0063]); that the diagnosis of the downstream side sensor 41 may be conducted while the target air-fuel ratio is switched between rich and lean alternately at short intervals, so alternated that the oxygen storage amount of the catalyst 20 is maintained greater than zero and smaller than the maximum storable amount (Hayashita, [0144]; claim 16); and that the abnormality judgment is performed only where the condition for diagnosis stands and the diagnostic target air-fuel ratio has been set, the routine otherwise ending without any judgment (Hayashita, [0147]–[0148], [0151]). Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify Yook such that the diagnostic is conducted, and the fault signal thereby provided, only during operation in which fuel is provided and the air-fuel ratio alternates between rich and lean, as taught by Hayashita, in order to increase the frequency with which the diagnostic can be completed. Yook conditions entry into the diagnostic on reduced fuel flow maintained for a predetermined period and on a vehicle speed of zero (Yook, [0017], [0019]), and Hayashita expressly identifies this shortcoming, teaching that condition-gated diagnostics are performed in accordance with the engine operating state, in some cases are not performed for a long period of time, and that for this reason it is sometimes not possible to diagnose abnormality over a long period (Hayashita, [0143]). In the modified mode, the desired first signal remains the commanded target air-fuel ratio to which the upstream sensor output is feedback-controlled (Hayashita, [0058], [0129]) and the expected second signal remains the value established in advance for the resulting downstream condition (Hayashita, [0086], [0144]), such that the limitations of claim 1 continue to be satisfied. One of ordinary skill would have had a reasonable expectation of success, the modification requiring no structural change to Yook, whose ECU 30 already sets the air/fuel ratio to a commanded value (Yook, [0014], [0023]) and already gates entry into the diagnostic on engine operating conditions (Yook, [0016]–[0020]).).
Regarding claim 7, Yook in view of Hayashita teaches the apparatus of claim 1 for the reasons set forth above, including the rationale for combining Yook and Hayashita. Hayashita further teaches: wherein the processing circuit determines the second signal differential when the upstream air-fuel equivalence ratio indicated by the first signal is maintained within a predefined value (Hayashita teaches that the fuel injection quantity is feedback-controlled based on the output of the upstream side air-fuel ratio sensor 40 so that the air-fuel ratio becomes the target air-fuel ratio, which target is set and maintained constant at a predetermined air-fuel ratio for the duration of the diagnosis, the output air-fuel ratio AFup of the upstream side sensor 40 changing to and being held at that target (Hayashita, [0058], [0131], [0134]; claim 15); and that sampling of the downstream side sensor output is deferred for the predetermined time Δt0 required for the output air-fuel ratio to converge following the setting of the target, the routine ending without any determination where that time has not elapsed, the difference between the detected value and the corresponding normal value being calculated only from samples taken thereafter (Hayashita, [0135], [0139], [0148]–[0149]). Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify Yook such that the difference between the detected rear oxygen sensor signal and the expected rear oxygen sensor value is determined when the upstream air-fuel equivalence ratio indicated by the front oxygen sensor is maintained at the commanded value, as taught by Hayashita, in order to ensure that the difference is attributable to the condition of the downstream sensor rather than to an incompletely established exhaust condition, Hayashita teaching that the value against which the downstream sensor output is compared is established in advance for a known, constant air-fuel ratio condition (Hayashita, [0086], [0138]). One of ordinary skill would have had a reasonable expectation of success, Yook likewise conditioning its failure determination on the front oxygen sensor output having reached its expected value and on the rich control having been carried out for the predetermined period (Yook, [0024], [0027]), and the modification being carried out by the same ECU 30 already monitoring that output (Yook, [0014]).).
Regarding claim 8, Yook in view of Hayashita teaches the apparatus of claim 1 for the reasons set forth above, including the rationale for combining Yook and Hayashita. Yook further discloses:
wherein the processing circuit is further structured to determine, using the second signal, that the second sensor is stuck rich or stuck lean (Yook discloses that at step S90 the ECU 30 determines whether the output value of the rear oxygen sensor 21 is less than the second threshold value of 0.45 V, an output below that threshold being the indication of a lean air/fuel mixture, an output above it being the indication of a rich air/fuel mixture (Yook, [0024]–[0025]); and that where the rear oxygen sensor output is less than 0.45 V while the front oxygen sensor output is greater than 0.5 V for the predetermined period during which a rich air/fuel ratio has been commanded, it is concluded that the rear oxygen sensor 21 has a failure (Yook, [0023], [0026]–[0027]); the ECU 30 thereby determines, using the second signal, that the rear oxygen sensor 21 continues to indicate lean notwithstanding a confirmed rich exhaust condition, that is, that the rear oxygen sensor is stuck lean, which satisfies the recited alternative expression.), and
wherein the notification indicates that the second sensor is stuck rich or stuck lean based on the determination (Yook discloses that upon that determination the ECU 30 generates a corresponding fault signal at step S92 (Yook, [0006], [0027]), the fault signal being generated in response to, and identifying, the failure of the rear oxygen sensor 21 so determined (Yook, [0005]–[0006], [0020]), as distinguished from the corresponding diagnosis signal generated at step S94 where the rear oxygen sensor output is greater than 0.45 V and the sensor is determined to operate normally (Yook, [0027]); under the broadest reasonable interpretation set forth above, this notification indicates that the second sensor is stuck lean based on the determination.).
Regarding claim 9, Yook discloses a method comprising:
receiving a first signal indicative of an upstream air-fuel equivalence ratio from a first sensor positioned upstream of an intake of a catalyst (Yook discloses a method for diagnosing a failure of a rear oxygen sensor of a vehicle (Yook, [0004]), in which a front oxygen sensor 20 is located upstream of a catalytic converter 3 disposed in an exhaust pipe 1, the front oxygen sensor generates a voltage signal proportional to the difference in oxygen content between the exhaust gas and ambient air, and the ECU 30 receives that signal (Yook, [0014]–[0015]), Yook further expressly correlating the sensor outputs to lambda, which Yook defines as the excess air factor indicating the deviation of the actual air/fuel ratio from the theoretically required ratio (Yook, [0023]; see also [0025]–[0026]).);
receiving a second signal indicative of a downstream air-fuel equivalence ratio from a second sensor positioned downstream of the intake of the catalyst (Yook discloses that a rear oxygen sensor 21 is located downstream of the catalytic converter 3, that the rear oxygen sensor likewise generates a voltage signal proportional to the difference in oxygen content between the exhaust gas and ambient air, and that the ECU 30 receives that signal (Yook, [0014]–[0015]), the rear oxygen sensor output being correlated to a rich or lean air/fuel mixture relative to lambda equal to one (Yook, [0025]–[0026]).);
providing a control signal to an engine to produce a desired first signal (Yook discloses that at step S70 the ECU 30 controls the injected fuel quantity, by way of injection command signals provided to a fuel injector 40, such that the air/fuel ratio becomes a predetermined rich air/fuel ratio of 0.85 lambda for a predetermined rich control period (Yook, [0014], [0023]), the desired first signal being the front oxygen sensor output that the commanded rich condition is expected to produce, namely an output greater than the first threshold value of 0.5 V (Yook, [0024], [0026]–[0027]).);
predicting an expected second signal based at least in part on the desired first signal (Yook discloses reasoning directly from the commanded rich condition to the value the rear oxygen sensor should produce, stating that when the air/fuel ratio is richer than a stoichiometric air/fuel ratio, that is, when lambda is less than one, the output voltage of the front oxygen sensor 20 should be greater than 0.5 V and the output voltage of the rear oxygen sensor 21 should also be greater than 0.45 V (Yook, [0026]), and reiterating that if the air/fuel mixture is regulated to be rich for the predetermined period, the output value of the front oxygen sensor should be greater than 0.5 V and the output value of the rear oxygen sensor should also be greater than 0.45 V (Yook, [0027]), such that the value of 0.45 V constitutes an expected second signal predicted from the desired first signal.);
comparing the first signal to the desired first signal (Yook discloses that at step S90 the ECU 30 determines whether the output value of the front oxygen sensor 20 is greater than a first threshold value for determining a rich air/fuel ratio, the first threshold value preferably being set as 0.5 V, and that if the output value of the front oxygen sensor is greater than the first threshold value the ECU 30 determines that the air/fuel mixture is rich (Yook, [0024]–[0025]).);
determining a second signal differential between the second signal and the expected second signal when the first signal is equal to the desired first signal (Yook discloses that at step S80 the ECU 30 simultaneously detects the output value of the front oxygen sensor 20 and the output value of the rear oxygen sensor 21 at a point after the rich control of step S70, and that at step S90 the ECU 30 evaluates the rear oxygen sensor output against the expected value of 0.45 V, the failure determination being expressly conditioned upon the front oxygen sensor output having reached its expected rich value of greater than 0.5 V, such that the evaluation of the second signal against its expected value is performed and acted upon only when the first signal has attained the desired first signal (Yook, [0024], [0027]); Yook thus teaches evaluating the second signal against the expected second signal under the recited condition, and see the discussion of Hayashita below with respect to performing that evaluation as a differential.); and
providing a fault signal in response to the second signal differential exceeding a threshold differential (Yook discloses that at step S90, if it is determined that the output voltage of the front oxygen sensor 20 is greater than 0.5 V and the output voltage of the rear oxygen sensor 21 is less than 0.45 V for the predetermined period, it is concluded that the rear oxygen sensor 21 has a failure, and the ECU 30 then generates a corresponding fault signal at step S92 (Yook, [0006], [0027]); Yook thus teaches providing a fault signal in response to the second signal deviating from the expected second signal, and see the discussion of Hayashita below with respect to the recited threshold differential.).
However, Yook does not expressly disclose expressing the evaluation of the second signal against the expected second signal as a second signal differential, or providing the fault signal in response to that differential exceeding a threshold differential, Yook instead performing a one-sided comparison of the rear oxygen sensor output against the expected value of 0.45 V.
Hayashita, in the same field of endeavor as Yook and as the claimed invention, namely on-board diagnosis of an exhaust gas sensor arranged downstream of a catalyst, teaches determining a second signal differential between the second signal and the expected second signal when the first signal is equal to the desired first signal, and providing a fault signal in response to that differential exceeding a threshold differential. Specifically: Hayashita teaches an ECU 31 that diagnoses abnormality of a downstream side air-fuel ratio sensor 41 arranged downstream of an oxygen-storing three-way exhaust purification catalyst 20, in an engine further having an upstream side air-fuel ratio sensor 40 arranged upstream thereof (Hayashita, [0041]–[0044]); that fuel injection is feedback-controlled based on the output of the upstream side sensor 40 so that the air-fuel ratio becomes a target air-fuel ratio, which is set and maintained constant in order to conduct the diagnosis, whereby the air-fuel ratio of the exhaust gas circulating around the downstream side sensor 41 is likewise maintained at that target value (Hayashita, [0058], [0129]–[0131], [0134]; claim 15); that the output which a normal downstream side sensor would produce under that known condition is detected or calculated in advance experimentally or by computation as a normal value (Hayashita, [0086], [0138]); that sampling is deferred until the predetermined time Δt0 required for the output air-fuel ratio to converge following the change of the target air-fuel ratio has elapsed (Hayashita, [0135], [0148]–[0149]); and that where the difference between the detected value of the output current of the downstream side sensor 41 and the corresponding normal value is a predetermined reference value or more, it is judged that a deviation has occurred at the downstream side air-fuel ratio sensor 41 (Hayashita, [0106], [0139]; claim 5).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the rear oxygen sensor evaluation performed at steps S90 and S92 of Yook to determine the difference between the detected rear oxygen sensor signal and the expected rear oxygen sensor value, and to provide the fault signal in response to that difference being a predetermined reference value or more, as taught by Hayashita, in order to detect a deviation of the downstream sensor even where that deviation is slight, which Hayashita teaches is necessary because a deviation in sensor output at the stoichiometric air-fuel ratio corrupts the air-fuel ratio control (Hayashita, [0008]–[0009], [0021], [0068]–[0069]). One of ordinary skill in the art would have recognized that in Yook a rear oxygen sensor exhibiting a moderate rich-side offset would nonetheless still produce an output exceeding 0.45 V and would therefore be passed as operating normally at step S90 (Yook, [0027]), leaving unmet the OBD-II diagnostic objective that Yook identifies as the purpose of the invention (Yook, [0002]–[0003]). The modification is the use of a known technique (Hayashita, [0106], [0139]) to improve a comparable diagnostic in the same way (see MPEP 2143(I)(C)), and one of ordinary skill would have had a reasonable expectation of success because it alters only the arithmetic form of a comparison that the same engine control unit already performs on the same sensor signal at the same point in the same diagnostic routine (Yook, [0026]–[0027]), the selection of a particular non-zero reference value being a matter of routine calibration. The rejection relies on Hayashita's teaching of a difference-versus-reference-value determination and does not require bodily incorporation of Hayashita's applied voltage control device 60 or limit current type sensor structure into Yook. See MPEP 2145(III).
Claim 10 depends from claim 9, which is rejected above over Yook in view of Hayashita, and recites method limitations corresponding to the apparatus limitations of claim 2, the scope and content of the recited limitations being substantially the same. Accordingly, the teachings of Yook in view of Hayashita, and the rationale for combining those references, that render claim 2 unpatentable likewise render claim 10 unpatentable.
Claim 11 depends from claim 10, which is rejected above over Yook in view of Hayashita, and recites a method limitation corresponding to the apparatus limitation of claim 3, the scope and content of the recited limitation being substantially the same. Accordingly, the teachings of Yook in view of Hayashita, and the rationale for combining those references, that render claim 3 unpatentable likewise render claim 11 unpatentable.
Claim 12 depends from claim 9, which is rejected above over Yook in view of Hayashita, and recites method limitations corresponding to the apparatus limitations of claim 4, the scope and content of the recited limitations being substantially the same. Accordingly, the teachings of Yook in view of Hayashita, the rationale for combining those references, the rationale for commanding a target air-fuel ratio leaner than stoichiometric, and the interpretation applied to "causes more fuel to be injected into the engine" set forth in the 35 U.S.C. 112(b) rejection above, that render claim 4 unpatentable likewise render claim 12 unpatentable. See MPEP 2173.06(I).
Claim(s) 13-16 and 18 is/are rejected under 35 U.S.C. 103 as being unpatentable over Hayashita et al. (US 2016/0131064 A1) in view of Yook (US 2003/0225505 A1).
Regarding claim 13, Hayashita discloses an apparatus comprising:
a processing circuit (Hayashita discloses an electronic control unit (ECU) 31 comprised of a digital computer provided with a RAM 33, ROM 34, CPU 35, input port 36, and output port 37 connected through a bidirectional bus 32, the ECU 31 acting as an abnormality diagnosis system for diagnosing abnormality of the downstream side air-fuel ratio sensor 41 (Hayashita, [0042]–[0043]).) structured to:
receive a key-on or key-off signal from an ignition circuit (Hayashita discloses that the condition for diagnosis of abnormality stands where the temperature of the downstream side air-fuel ratio sensor 41 is at or above the active temperature and the diagnosis of that sensor for abnormality has not yet finished after the internal combustion engine has been started up or the ignition key of the vehicle mounting the internal combustion engine has been turned on, that condition being evaluated by the ECU 31 at step S11 (Hayashita, [0117]); evaluation of that condition requires that the ECU 31 receive an indication that the ignition key has been turned on, that is, a key-on signal from the vehicle ignition.);
provide a fuel cut or lean run signal to an engine (Hayashita discloses that the fuel injector 11 injects fuel in accordance with an injection signal (Hayashita, [0039]) and that the output port 37 of the ECU 31 is connected through corresponding drive circuits 45 to the fuel injectors 11 (Hayashita, [0043]); and that at the time of deceleration of the vehicle, even in the state where the crankshaft or piston 3 is operating, the feed of fuel from the fuel injector 11 to the combustion chamber 5 is stopped as fuel cut control (Hayashita, [0089]), the ECU 31 judging at step S13 whether fuel cut control is underway before proceeding with the diagnosis (Hayashita, [0118]); alternatively, Hayashita discloses setting the target air-fuel ratio to a lean set air-fuel ratio AFTlean, for example 15, leaner than the stoichiometric air-fuel ratio of 14.6, whereupon the air-fuel ratio of the exhaust gas flowing into the catalyst 20 becomes a lean air-fuel ratio (Hayashita, [0060], [0063]).);
receive a lambda signal indicative of a downstream air-fuel equivalence ratio from a sensor positioned downstream of an intake of a catalyst (Hayashita discloses a downstream side air-fuel ratio sensor 41 arranged in the exhaust pipe 22 downstream of the upstream side exhaust purification catalyst 20, which detects the air-fuel ratio of the exhaust gas flowing out from that catalyst, the output of the sensor being input through a corresponding AD converter 38 to the input port 36 of the ECU 31 (Hayashita, [0041]–[0042]), the output current of the sensor changing linearly with the exhaust air-fuel ratio and being zero at the stoichiometric air-fuel ratio (Hayashita, [0055]).); and
provide a fault signal in response to the lambda signal indicating the downstream air-fuel equivalence ratio is less than one (Hayashita discloses that upon commencement of fuel cut control the oxygen storage amount of the catalyst 20 reaches its maximum storable amount and atmospheric gas flows out of the catalyst 20, whereupon the output air-fuel ratio of the downstream side sensor 41 changes to a lean air-fuel ratio of extremely large lean degree corresponding to the atmospheric gas (Hayashita, [0093]); that the output which a normal downstream side sensor would produce under that atmospheric gas condition is detected or calculated in advance experimentally or by computation as a normal value (Hayashita, [0104]); and that where the difference between the detected value of the output current of the downstream side sensor 41 and the corresponding normal value is a predetermined reference value or more, it is judged that a deviation has occurred at the downstream side air-fuel ratio sensor 41 (Hayashita, [0106]); Hayashita further identifies the fault of concern as the downstream side sensor indicating a rich air-fuel ratio notwithstanding the actual air-fuel ratio of the exhaust flowing out of the catalyst, teaching that if the air-fuel ratio detected by the downstream side sensor becomes a rich air-fuel ratio regardless of the actual air-fuel ratio, the control no longer works (Hayashita, [0068]); accordingly, in the apparatus of Hayashita a downstream lambda signal indicating an air-fuel equivalence ratio of less than one under the commanded fuel cut condition necessarily differs from the established lean normal value by more than the predetermined reference value, and the abnormality judgment is thereby made.).
Hayashita does not expressly disclose a notification circuit structured to provide a notification indicating that the sensor is faulty in response to receiving the fault signal.
Yook, in the same field of endeavor as Hayashita and as the claimed invention, namely on-board diagnosis of an exhaust gas sensor arranged downstream of a catalyst, teaches a notification circuit structured to provide a notification indicating that the sensor is faulty in response to receiving the fault signal. Specifically: Yook discloses an ECU 30 including a microprocessor, a memory, and other necessary hardware and software components (Yook, [0014]), which generates a fault diagnosis signal specifically identifying the rear oxygen sensor 21 as having failed (Yook, [0005]–[0006], [0020], [0027]), as distinguished from the corresponding diagnosis signal generated where the rear oxygen sensor is determined to operate normally (Yook, [0027]); Yook situates this reporting within the OBD-II on-board diagnostic framework, which requires a device for diagnosing a malfunction of an emissions-related diagnosing device (Yook, [0002]–[0003]).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to modify the apparatus of Hayashita to generate, in response to the abnormality judgment, a fault diagnosis signal identifying the downstream side air-fuel ratio sensor as faulty, as taught by Yook, in order to report the diagnosed malfunction as required for on-board diagnostic compliance, Yook teaching that emission regulations require diagnosis of a failure of the oxygen sensor and that the on-board diagnostic standard requires a device for diagnosing such malfunctions (Yook, [0002]–[0003]). One of ordinary skill in the art would have recognized that a diagnostic result is of no practical use unless reported, Hayashita already judging the mode of abnormality of the downstream side sensor within the ECU 31 (Hayashita, [0106], [0151]), and would have had a reasonable expectation of success, the modification requiring no structural change and being carried out by the same ECU that already performs the judgment.
Regarding claim 14, Hayashita in view of Yook teaches the apparatus of claim 13 for the reasons set forth above, including the rationale for combining Hayashita and Yook. Hayashita further discloses: wherein the fuel cut or lean run signal is structured to actuate the engine through at least one cycle with limited fuel so that the catalyst is flooded with oxygen (Hayashita discloses that at the time of deceleration of the vehicle, even in the state where the crankshaft or piston 3 is operating, that is, during operation of the internal combustion engine, the feed of fuel from the fuel injector 11 to the combustion chamber 5 is stopped as fuel cut control, and that if fuel cut control is performed the oxygen storage amount of the exhaust purification catalyst 20 reaches the maximum storable amount of oxygen (Hayashita, [0089]); Hayashita further discloses that upon commencement of fuel cut control atmospheric gas flows out from the engine body 1 and into the catalyst 20, the oxygen in that atmospheric gas being stored in the catalyst 20 until the oxygen storage amount immediately reaches the maximum storable amount, whereupon atmospheric gas flows out from the catalyst 20 (Hayashita, [0093]); the engine is thereby actuated through at least one cycle with limited fuel, the crankshaft and piston continuing to operate while the feed of fuel is stopped, so that the catalyst is flooded with oxygen, the catalyst being filled to its maximum storable oxygen amount and thereafter passing atmospheric gas.).
Regarding claim 15, Hayashita in view of Yook teaches the apparatus of claim 13 for the reasons set forth above, including the rationale for combining Hayashita and Yook. Hayashita further discloses: wherein the lambda signal is received after the key-on or key-off signal is received (Hayashita discloses a control routine in which the ECU 31 first judges at step S11 whether the condition for diagnosis of abnormality stands, that condition being that the diagnosis of the downstream side air-fuel ratio sensor 41 has not yet finished after the internal combustion engine has been started up or the ignition key of the vehicle has been turned on, the routine being made to end without further action where that condition does not stand (Hayashita, [0117]); and that only where that condition stands does the routine proceed to the subsequent steps, at which fuel cut control is judged to be underway at step S13, the applied voltage is set at step S14, and the output current of the downstream side air-fuel ratio sensor 41 is judged to have stabilized and is thereafter sampled and averaged at steps S15 through S17 (Hayashita, [0118]–[0122]); the output of the downstream side sensor 41 relied upon for the diagnosis is therefore received after the ignition key-on condition is received and evaluated.).
Regarding claim 16, Hayashita in view of Yook teaches the apparatus of claim 13 for the reasons set forth above, including the rationale for combining Hayashita and Yook. Hayashita further discloses: wherein the lambda signal is received after the fuel cut or lean run signal is provided (Hayashita discloses a control routine in which the ECU 31 judges at step S13 whether fuel cut control is underway, the routine being made to end without further action where fuel cut control is not underway, and proceeding to the subsequent steps only after fuel cut control has been started (Hayashita, [0118]–[0119]); and that only thereafter is the output current of the downstream side air-fuel ratio sensor 41 judged to have stabilized at step S15, the routine again ending without further action where the output has not stabilized, and the output being sampled and averaged at steps S16 and S17 upon elapse of the constant time Δt (Hayashita, [0120]–[0122]); the output of the downstream side sensor 41 relied upon for the diagnosis is therefore received after the fuel cut signal is provided.).
Regarding claim 18, Hayashita in view of Yook teaches the apparatus of claim 13 for the reasons set forth above, including the rationale for combining Hayashita and Yook. Hayashita further discloses: wherein the lambda signal indicating the downstream air-fuel equivalence ratio is less than one corresponds to the sensor being stuck rich (Hayashita discloses that the output current of the downstream side air-fuel ratio sensor 41 changes linearly with the exhaust air-fuel ratio and is zero at the stoichiometric air-fuel ratio, the output being smaller as the air-fuel ratio is richer (Hayashita, [0055]), such that a lambda signal indicating an air-fuel equivalence ratio of less than one is an indication of a rich air-fuel ratio; that upon fuel cut control the catalyst 20 is filled to its maximum storable oxygen amount and atmospheric gas thereafter flows out of the catalyst, so that the exhaust reaching the downstream side sensor 41 is of an extremely large lean degree (Hayashita, [0089], [0093]); and that where an abnormality occurs, the output current of the air-fuel ratio sensor deviates from the value appropriate to the actual exhaust air-fuel ratio across the entire region of the exhaust air-fuel ratio, so that the sensor indicates an air-fuel ratio at the rich side of the actual air-fuel ratio (Hayashita, [0067]); Hayashita further identifies this condition as the fault of concern, teaching that if the air-fuel ratio detected by the downstream side sensor becomes a rich air-fuel ratio regardless of the actual air-fuel ratio of the exhaust flowing out of the catalyst, the control no longer works (Hayashita, [0068]); accordingly, in the apparatus of Hayashita in view of Yook, a lambda signal indicating an air-fuel equivalence ratio of less than one under the commanded fuel cut condition corresponds to the downstream side sensor being stuck rich, that is, indicating rich notwithstanding the actual lean exhaust condition.).
Claim(s) 17 is/are rejected under 35 U.S.C. 103 as being unpatentable over Hayashita et al. (US 2016/0131064 A1) in view of Yook (US 2003/0225505 A1), and further in view of Park et al. (US 2014/0148991 A1).
Regarding claim 17, Hayashita in view of Yook teaches the apparatus of claim 13 for the reasons set forth above, including the rationale for combining Hayashita and Yook. Hayashita in view of Yook does not expressly disclose that when the key-on signal is received a time is recorded since the last key-off signal was received, or that the fault signal is only provided when that time exceeds a minimum absorption time.
Park teaches wherein when the key-on signal is received, a time is recorded since the last key-off signal was received, and wherein the fault signal is only provided when the time exceeds a minimum absorption time. Specifically: Park teaches a vehicle controller 100 comprising a processor and memory (Park, [0030], [0038]) and including an ignition off time storing unit 110 that stores the time at which the ignition is turned off, an ignition on time detecting unit 120 that detects the ignition on time at which the ignition is turned on after the ignition has been turned off, an elapsed time calculating unit 130 including a timer that calculates the elapsed time, that is, a soaking time, from the ignition off time to the ignition on time, and a failure diagnosis performing unit 140 that determines whether that elapsed time is equal to or greater than a predetermined time, diagnoses failure of the sensor where it is, and stops the diagnosis where it is not (Park, [0019], [0040]–[0041], [0044]–[0047]); and that the predetermined time is set based on the time until a residual physical condition in the monitored device is eliminated after the ignition off time, because that residual condition would otherwise cause the sensor to be diagnosed as having failed (Park, [0016], [0046]).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify the apparatus of Hayashita in view of Yook to store the ignition off time, calculate upon key-on the elapsed time since that key-off, and provide the fault signal only where that elapsed time exceeds a predetermined threshold, as taught by Park, in order to prevent an incorrect diagnosis that the downstream sensor has failed. The fault determination of Hayashita in view of Yook rests on the premise that the exhaust reaching the downstream sensor is lean because the catalyst 20 has been filled to its maximum storable oxygen amount (Hayashita, [0089], [0093], [0104]), and where the diagnostic is enabled following key-on (Hayashita, [0117]) one of ordinary skill would have recognized that if insufficient time has elapsed since shutdown the catalyst may not have reached that state, causing the downstream sensor to report an air-fuel equivalence ratio of less than one for reasons unrelated to any sensor fault. Park addresses that same failure mode, teaching that where the ignition is turned on before a predetermined time has passed after ignition off, a residual condition remains and the sensor is consequently determined to have failed in the diagnosing process, and that the incorrect diagnosis is prevented by gating the diagnosis on the soaking time (Park, [0011], [0014], [0020]); Park is therefore reasonably pertinent to the particular problem with which Applicant was concerned and is analogous art (see MPEP 2141.01(a)). One of ordinary skill would have had a reasonable expectation of success, Park implementing its units in a vehicle controller, Hayashita's ECU 31 comprising a CPU 35, RAM 33, and ROM 34 (Hayashita, [0042]), and Yook's ECU 30 already detecting a monitoring time using a timer 31 (Yook, [0014]).
Claim(s) 19 is/are rejected under 35 U.S.C. 103 as being unpatentable over Hayashita et al. (US 2016/0131064 A1) in view of Yook (US 2003/0225505 A1), and further in view of Hayashi et al. (US 2007/0012564 A1).
Regarding claim 19, Hayashita in view of Yook teaches the apparatus of claim 13 for the reasons set forth above, including the rationale for combining Hayashita and Yook. Hayashita in view of Yook does not expressly disclose that when the key-off signal is received, the processing circuit provides the fuel cut signal to the engine, Hayashita effecting fuel cut control at the time of deceleration of the vehicle (Hayashita, [0089]).
Hayashi teaches wherein when the key-off signal is received, the processing circuit provides the fuel cut signal to the engine. Specifically: Hayashi teaches an ECU 1 including a microcomputer 31 having a CPU, ROM and RAM, to which signals from various switches including an ignition switch are input and which outputs drive signals to an injector 23 for fuel injection through an output circuit 61, the ECU 1 detecting an abnormality of a downstream-side oxygen sensor 17 disposed downstream of a catalyst converter 13 (Hayashi, [0029], [0031], [0033], [0040]); that in a second abnormality detection processing the microcomputer 31 determines at step S410 whether the ignition switch is turned off, the processing ending where it is not, and upon the first execution after the ignition switch changes from ON to OFF carries out a momentary forcible fuel injection at step S420 only for a certain time (Hayashi, [0102]–[0104]); and that fuel is thereafter injected no further, so that for the stop delay period from the point the ignition switch is turned off to the point the engine stops, the state similar to that at the time of fuel cut-off during operation of the engine is provided, during which the output voltage of the oxygen sensor 17 is monitored at step S430 (Hayashi, [0108]–[0109]; see also claim 26).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify the apparatus of Hayashita in view of Yook such that the fuel cut signal is provided in response to receipt of the key-off signal, as taught by Hayashi, in order to increase the opportunities to complete the downstream sensor diagnostic. Hayashita conditions its diagnostic on fuel cut control being underway (Hayashita, [0118]) and expressly recognizes that fuel cut control is performed in accordance with the engine operating state, in some cases is not performed for a long period of time, and that for this reason it is sometimes not possible to diagnose abnormality over a long period (Hayashita, [0143]); Hayashi addresses that same limitation, teaching that by execution of the second abnormality detection processing the abnormality of the oxygen sensor 17 can be confirmed not only when the fuel cut-off is effected but also when the ignition switch is turned off, and can thereby be quickly and accurately detected (Hayashi, [0110]). One of ordinary skill would have had a reasonable expectation of success, both references implementing the diagnostic in an engine control unit that drives the fuel injectors through an output circuit and both diagnosing an oxygen sensor downstream of a catalyst under a fuel cut condition (Hayashita, [0042]–[0043], [0089]; Hayashi, [0033], [0040], [0042]).
Claim(s) 20 is/are rejected under 35 U.S.C. 103 as being unpatentable over Hayashita et al. (US 2016/0131064 A1) in view of Yook (US 2003/0225505 A1), further in view of Hayashi et al. (US 2007/0012564 A1), and further in view of Yurgil et al. (US 2004/0159094 A1).
Regarding claim 20, Hayashita in view of Yook and further in view of Hayashi teaches the apparatus of claim 19 for the reasons set forth above, including the rationales for combining those references. Those references do not expressly disclose that the fuel cut signal causes the engine to operate in a fuel cut condition for a predetermined amount of time, Hayashi teaching that the fuel cut state following ignition switch turn-off persists until the engine stops and that more or less time is taken from that point to the point the engine stops (Hayashi, [0108]).
Yurgil teaches wherein the fuel cut signal causes the engine to operate in a fuel cut condition for a predetermined amount of time. Specifically: Yurgil teaches a controller 16 that communicates with a fuel system 28 to regulate fuel flow to an engine 12, the exhaust 14 including a catalytic converter 22 and an outlet oxygen sensor 26 downstream thereof communicating with the controller 16 (Yurgil, [0021]); that the engine 12 is operated in the fuel cut-off mode for a predetermined period of time, the predetermined time period being calibrated to completely saturate the catalytic converter 22 with oxygen (Yurgil, [0032]; see also claims 6, 15 and 20); and that the controller determines at step 106 whether the catalytic converter 22 has been exposed to air flow for a time sufficient to achieve oxygen saturation, control looping back where it has not (Yurgil, [0043]).
Therefore, it would have been obvious to one of ordinary skill in the art before the effective filing date of the claimed invention to further modify the apparatus of Hayashita in view of Yook and Hayashi such that the fuel cut signal provided upon key-off causes the engine to operate in the fuel cut condition for a predetermined amount of time, as taught by Yurgil, in order to ensure that the catalyst has been saturated with oxygen before the downstream sensor output is evaluated. The fault determination of the combination rests on the premise that the exhaust reaching the downstream sensor is lean because the catalyst has been filled to its maximum storable oxygen amount (Hayashita, [0089], [0093], [0104]), and because Hayashi teaches that the duration of the post-key-off fuel cut state is variable (Hayashi, [0108]), one of ordinary skill would have recognized that on a given shutdown that premise may not be established before the engine stops; Yurgil addresses that same need with a fuel cut-off period of predetermined duration calibrated to completely saturate the catalyst (Yurgil, [0032], [0043]). One of ordinary skill would have had a reasonable expectation of success, all four references implementing the diagnostic in an engine controller that regulates fuel flow to the engine and evaluates the output of an oxygen sensor downstream of a catalyst (Hayashita, [0042]–[0043]; Yook, [0014]; Hayashi, [0033], [0040]; Yurgil, [0021]).
Conclusion
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/RAJSHEED O BLACK-CHILDRESS/Examiner, Art Unit 2685
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