JP2006234431A - Test apparatus and vehicle produced using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To test whether a failure diagnostic system, which detects anomalies in output characteristics due to degradation etc. with the passage of time of sensors (representatively, an airflow meter) constituting internal combustion engines, normally functions or not. <P>SOLUTION: An airflow meter 42 provided for an engine 10 outputs an output voltage Vaf according to the amount of intake air. An engine ECU 300 has a failure diagnostic system function of the airflow meter 42 based on comparisons between the amount of intake air estimated by the operating conditions of the engine 10 and the detected amount of intake air corresponding to the output voltage Vaf. A test apparatus 500 receives the output voltage Vaf from the airflow meter 42 at test, converts it into a corresponding simulated voltage Vsm when the airflow meter 42 is in a degraded state with the passage of time, and outputs it. The engine ECU 300 diagnoses failure of the airflow meter 42 through the use of the simulated voltage Vsm instead of the output voltage Vaf. It is thereby possible to test whether the failure diagnostic system can accurately detect degraded conditions with the passage of time of the airflow meter 42 as anomalies or not. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a test apparatus, and more particularly to a test apparatus for checking whether or not a failure diagnosis system for an internal combustion engine of a vehicle functions normally and a vehicle produced using the same.

  Prior to shipment of automobiles produced in factories, tests are conducted to check whether the regulations are satisfied, including exhaust gas regulations, and other satisfactory specifications. For example, Patent Document 1 is configured to selectively call a program corresponding to an engine specification from a program memory storing a program (injection, ignition, intake air, etc.) corresponding to various engines during an engine bench test. An engine control device for testing is disclosed.

  In general, automobiles are equipped with a self-diagnosis system, which automatically detects the occurrence of an abnormality or failure by self-diagnosis of devices and sensors. . The failure / abnormality of the devices / sensors detected by the self-diagnosis is notified to the driver by display on a diagnosis monitor or the like.

However, in sensors, not only complete failure / abnormality such as disconnection of an output signal due to disconnection or the like, but also deterioration of characteristics over time occurs. For example, Patent Document 1 points out that the output characteristics of an air flow meter for detecting the intake air amount provided in a diesel engine change over time, and correction for correcting such changes in output characteristics. A configuration that maintains the detection accuracy of the intake air amount by introducing a coefficient is disclosed.
JP 2001-107797 A Akihiro Takeuchi, “Engine Control Device for Test Bench”, Japan Institute of Invention Technology Bulletin 94-14816, August 1, 1994

  In particular, in the United States, where exhaust gas regulations are strict, CARB (California Air Resources Board) and the like are obliged to self-diagnose abnormalities / failures of various devices and sensors that lead to deterioration of exhaust emissions from engines. In particular, it is required that the self-diagnosis system detect the occurrence of deterioration over time that causes a malfunction in engine operation even if various devices and sensors do not completely fail.

  For example, since the air-fuel ratio control in the engine is performed based on the intake air amount detected by the air flow meter, if the intake air amount cannot be accurately measured due to the deterioration of the air flow meter, the exhaust emission will deteriorate. . For this reason, the CARB regulations require that a self-diagnosis system capable of detecting an output characteristic abnormality due to aged deterioration or the like in an air flow meter be installed.

  Therefore, prior to shipment of the manufactured automobile, it is necessary to test whether the self-diagnosis system can normally detect an abnormality. However, Patent Document 1 and Non-Patent Document 1 particularly disclose a function that performs a test in consideration of characteristic deterioration of various devices and sensors and a test for a self-diagnosis system that automatically detects such characteristic deterioration. Not.

  The present invention is for solving such problems, and an object of the present invention is to provide a failure diagnosis system for detecting an output characteristic abnormality due to aging deterioration of a sensor (measuring device) constituting an internal combustion engine. It is to provide a test apparatus for testing whether or not it functions normally.

  A test apparatus according to the present invention is a test apparatus that indicates whether or not a failure diagnosis system for an internal combustion engine functions normally, and includes a pseudo deterioration means and a determination confirmation means. In addition, the internal combustion engine measures a predetermined state quantity of the internal combustion engine and generates an output signal according to the measured state quantity, and based on a comparison between the output signal and the operating state of the internal combustion engine, And a control device configured to perform failure diagnosis. The pseudo deterioration means receives an output signal from the measuring device, converts it into an output signal that simulates the deterioration state of the measuring device, and outputs the output signal. At the time of the test, the control device performs a failure diagnosis of the measuring device based on a comparison between the output signal converted by the pseudo deterioration means and the operating state of the internal combustion engine. The determination confirmation means confirms whether or not a failure has been detected by the control device.

  According to the test apparatus, the output voltage from the measurement apparatus simulating the deterioration state can be input to the control apparatus to perform a failure diagnosis of the measurement apparatus. Therefore, it is possible to test whether or not the failure diagnosis system that automatically detects the occurrence of deterioration in the measuring device provided in the internal combustion engine operates normally.

  Preferably, in the test apparatus of the present invention, the pseudo deterioration means includes a test input means for receiving a test input, a signal conversion means for converting an output signal from the measurement apparatus in accordance with the test input to the test input means, and a signal conversion Signal output means for sending the output signal converted by the means to the control device.

  According to the above test apparatus, the simulated deterioration state can be made variable according to the test input, so the degree of freedom in testing the failure diagnosis system is improved, and the failure diagnosis system automatically detects the deterioration state of various patterns. You can test whether it can be detected.

  Also preferably, in the test apparatus of the present invention, the signal conversion means converts the output signal by multiplication of a coefficient determined by the test input and the output signal from the measurement apparatus.

  According to the test apparatus, the deterioration state can be simulated for a wide range of output voltages (for example, an air flow meter output voltage), that is, for a wide range of state quantities (for example, intake air amount), by simple calculation.

  Alternatively, preferably, in the test apparatus of the present invention, the output signal from the measuring apparatus is an analog voltage, and the signal conversion means includes a first auxiliary conversion means, a calculation means, and a second auxiliary conversion means. Including. The first auxiliary conversion means converts the output signal from the measuring device into a first digital signal. The calculating means performs a predetermined calculation between the first digital signal from the first auxiliary means and the digital signal corresponding to the test input. A calculation result obtained by the calculation means is converted into an analog voltage. Further, the signal output means receives the analog voltage from the second auxiliary conversion means as an output signal converted by the signal conversion means.

  According to the test apparatus, the conversion of the output voltage simulating the deterioration state can be performed by digital calculation. Therefore, the simulated output voltage can be set with high accuracy. Moreover, since the degree of freedom of the deterioration state that can be simulated (for example, aging deterioration of different patterns) is increased, the test effect of the failure diagnosis system can be increased.

  More preferably, in the test device of the present invention, the failure diagnosis by the control device relates to exhaust emission from the internal combustion engine.

  According to the test apparatus, it is possible to test whether or not the failure diagnosis system that automatically detects the occurrence of deterioration of the measurement apparatus that affects the deterioration of exhaust emission operates normally.

  Alternatively, more preferably, in the test apparatus of the present invention, the measurement device is an air flow meter that measures the amount of intake air to the internal combustion engine.

  According to the above test apparatus, it is possible to test whether or not the failure diagnosis system that automatically detects the occurrence of deterioration of the air flow meter that measures the intake air amount, which is a state quantity necessary for air-fuel ratio control, operates normally. .

  In particular, a vehicle according to the present invention is produced using the test device according to any one of claims 1 to 6.

  The vehicle can be shipped after confirming whether or not a failure diagnosis system that automatically detects the occurrence of deterioration in a measuring device provided in the internal combustion engine operates normally.

  According to the test apparatus of the present invention, the deterioration signal of the measurement device is detected by the failure diagnosis system by converting the output signal from the measurement device (sensor) so as to simulate the deterioration state and inputting it to the failure diagnosis system. A test can be performed to confirm whether it is possible.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same or corresponding parts are denoted by the same reference numerals, and the description thereof will not be repeated.

  FIG. 1 shows a schematic configuration diagram of an engine system corresponding to an internal combustion engine to be tested by a test apparatus according to an embodiment of the present invention. Although FIG. 1 shows an in-line four-cylinder engine as an engine, the application of the present invention is not limited to such an engine.

  Referring to FIG. 1, engine 10 includes four cylinders 110, and each cylinder 110 is connected to a common surge tank 30 via a corresponding intake manifold 20. The surge tank 30 is connected to the air cleaner 50 via the intake duct 40. An air flow meter 42 is disposed in the intake duct 40 and a throttle valve 70 driven by an electric motor 60 is disposed. The opening of the throttle valve 70 is controlled independently of the accelerator pedal 100 based on an output signal of an engine ECU (Electronic Control Unit) 300. On the other hand, each cylinder 110 is connected to a common exhaust manifold 80, and this exhaust manifold 80 is connected to a three-way catalytic converter 90.

  A fuel injection injector 120 that injects fuel into the intake passage is disposed for each cylinder 110. The fuel injection injector 120 is controlled based on the output signal of the engine ECU 300. Each fuel injection injector 120 is connected to a common fuel distribution pipe 160. The fuel injection injector 120 may be provided as an in-cylinder injector that directly injects fuel into the cylinder. Such an in-cylinder injector and the fuel injection injector 120 that injects fuel into the intake passage; It is good also as a structure which arrange | positions both.

  The fuel distribution pipe 160 is connected to an electric motor driven low-pressure fuel pump 180 through a fuel pressure regulator 170. Further, the low pressure fuel pump 180 is connected to the fuel tank 200 via the fuel filter 190. The fuel pressure regulator 170 returns a part of the fuel discharged from the low-pressure fuel pump 180 to the fuel tank 200 when the fuel pressure of the fuel discharged from the low-pressure fuel pump becomes higher than a predetermined set fuel pressure. It is configured. For this reason, it can prevent that the fuel pressure currently supplied to the fuel-injection injector 120 becomes higher than the said setting fuel pressure.

  The engine ECU 300 is composed of a digital computer, and is connected to each other via a bidirectional bus 310, a ROM (Read Only Memory) 320, a RAM (Random Access Memory) 330, a CPU (Central Processing Unit) 340, and an input port 350. And an output port 360.

  The air flow meter 42 generates an output voltage corresponding to the intake air amount. Output voltage Vaf from air flow meter 42 (hereinafter also referred to as air flow meter output voltage Vaf) is transmitted to A / D converter 370 via path 375 and input to input port 350 via A / D converter 370. . In the embodiment of the present invention, the type of the air flow meter 42 is not particularly limited, and a commonly used hot wire type air flow meter, flap type air flow meter, Karman vortex type air flow meter or the like is arbitrarily applied. It is possible.

  A water temperature sensor 380 that generates an output voltage corresponding to the engine cooling water temperature (engine cooling water temperature) is attached to the engine 10, and the output voltage of the water temperature sensor 380 is input to the input port 350 via the A / D converter 390. Is done.

  Further, an air-fuel ratio sensor 420 that generates an output voltage corresponding to the oxygen concentration in the exhaust gas is attached to the exhaust manifold 80 upstream of the three-way catalytic converter 90. The output voltage of the air-fuel ratio sensor 420 is A / The signal is input to the input port 350 via the D converter 430.

The air-fuel ratio sensor 420 is a global air-fuel ratio sensor (linear air-fuel ratio sensor) that generates an output voltage corresponding to the air-fuel ratio of the air-fuel mixture burned by the engine 10. The air-fuel ratio sensor 420 may be an O ₂ sensor that detects whether the air-fuel ratio of the air-fuel mixture burned in the engine 10 is rich or lean with respect to the stoichiometric air-fuel ratio. Good.

  The accelerator pedal 100 is connected to an accelerator opening sensor 440 that generates an output voltage proportional to the depression amount of the accelerator pedal 100, and the output voltage of the accelerator opening sensor 440 is input to the input port 350 via the A / D converter 450. Is input. The input port 350 is connected to a rotational speed sensor 460 that generates an output pulse representing the engine rotational speed.

  In the ROM 320 of the engine ECU 300, the value of the fuel injection amount set corresponding to the operating state based on the engine load factor and the engine speed obtained by the accelerator opening sensor 440 and the engine speed sensor 460 described above, and the engine Correction values based on the cooling water temperature are stored in advance as a map. Further, the intake air amount measured by the air flow meter 42 is reflected in the fuel injection amount setting so that the air-fuel ratio in the cylinder 110 becomes a predetermined value.

  Therefore, if the air flow meter 42 is deteriorated and does not generate an output voltage corresponding to the intake air amount, the fuel injection amount setting by the engine ECU 300 is not performed normally, and the air-fuel ratio is out of the predetermined range, and the exhaust emission deteriorates. There is a risk.

  For this reason, the engine system is provided with an air flow meter failure diagnosis system 300 # as shown in FIG. The function of failure diagnosis system 300 # is realized by execution of a predetermined program by engine ECU 300.

  Referring to FIG. 2, failure diagnosis system 300 # includes an intake air amount estimation unit 302 that estimates the intake air amount from engine operating conditions, and a determination unit 304 that performs abnormality determination of the air flow meter 42.

  The intake air amount estimation unit 302 obtains an intake air amount estimated value Eair from the engine operating conditions, typically the accelerator opening and the engine speed. The determination unit 304 determines whether or not the air flow meter 42 is abnormal based on the air flow meter output voltage Vaf and the intake air amount estimated value Eair that are input to the engine ECU 300 via the path 375. The determination unit 304 outputs a determination flag Jaf indicating a determination result.

  As shown in FIG. 3, the air flow meter 42 is configured so that the output voltage Vaf increases according to the increase in the intake air amount according to the characteristic line 305 in the normal state.

  Referring to FIG. 2 again, determination unit 304 obtains output voltage estimated value Vaf # corresponding to intake air amount estimated value Eair by intake air amount estimating unit 302 in accordance with output characteristic line 305 of the air flow meter shown in FIG. calculate. Further, determination unit 304 performs abnormality detection by comparing output voltage estimated value Vaf # with airflow meter output voltage Vaf. For example, when the error between the two is larger than the determination value, it is determined that the air flow meter 42 is abnormal.

  Alternatively, the determination unit 304 calculates the measured intake air amount Qair from the air flow meter output voltage Vaf according to the output characteristic line 305, and calculates the calculated intake air amount Qair and the estimated intake air amount by the intake air amount estimation unit 302. Abnormality detection is performed by comparison with Air. Also in this case, it is determined that there is an abnormality in the air flow meter 42 when the error between the two compared is larger than the determination value.

  Referring to FIG. 3 again, when the characteristic of the output voltage with respect to the intake air amount changes from the original characteristic line 305 as indicated by reference numeral 307 in accordance with the aging deterioration of the air flow meter 42, the actual intake air amount is As the output voltage Vaf decreases, the intake air amount is erroneously detected.

  When such a phenomenon occurs, the fuel injection amount is not normally set by the engine ECU 300 as described above, and the air-fuel ratio cannot be maintained within a predetermined range, so that exhaust emission deteriorates. Therefore, it is determined whether or not the failure diagnosis system 300 # shown in FIG. 2 functions normally by the test apparatus according to the embodiment of the present invention so that the output characteristic abnormality due to the aging deterioration of the air flow meter 42 can be automatically detected. Need to test.

  Referring to FIG. 4, test apparatus 500 according to the embodiment of the present invention is connected to air flow meter 42 and engine ECU 300 by wires 502 and 504 before vehicle 1000 is shipped, and air flow meter 42 in engine ECU 300 is connected. Test whether the fault diagnosis system is functioning normally.

  The test apparatus 500 receives the output voltage Vaf from the air flow meter 42 via the wiring 502 and generates a simulated voltage Vsm that simulates the deterioration state of the air flow meter 42. Simulated voltage Vsm is applied to engine ECU 300 via wiring 504. That is, at the time of the test, failure diagnosis system 300 # detects abnormality of air flow meter 42 using simulated voltage Vsm from test apparatus 500 instead of air flow meter output voltage Vaf.

  The correspondence relationship between the configuration shown in FIG. 4 and the present invention will be described. The air flow meter 42 corresponds to the “measuring device” in the present invention, and the engine ECU 300 corresponds to the “control device” in the present invention. The vehicle 1000 corresponds to a vehicle produced using the test device according to the present invention.

  FIG. 5 is a block diagram illustrating in detail the configuration of the test apparatus 500 shown in FIG.

  Referring to FIG. 5, a test apparatus 500 includes a test start switch 505, a voltage input circuit 510, an A / D converter 520, a test input circuit 530, a deterioration simulation calculation unit 540, a latch circuit 550, A D / A converter 560 and a voltage output circuit 570 are included.

  Test start switch 505 is connected between power supply voltage Vcc and node Ne. Node Ne is connected to ground voltage GND through resistor Rs. Thus, when the test start switch 505 is turned on, the node Ne is connected to the power supply voltage Vcc, so that the node Ne becomes a logic high level and the test execution bit RBs is set to a high level. On the other hand, when the test start switch 505 is off, the node Ne is pulled down to the ground voltage GND, so that the test execution bit RBs is set to a logic low level.

  The voltage input circuit 510 is constituted by a voltage follower circuit using an operational amplifier, and impedance-converts and outputs the air flow meter output voltage Vaf transmitted through the wiring 502.

  The A / D converter 520 converts the air flow meter output voltage Vaf impedance-converted by the voltage input circuit 510 into a digital voltage Daf. That is, the digital voltage Daf is composed of a multi-bit digital signal indicating the magnitude of the airflow meter output voltage Vaf.

  Test input circuit 530 includes an input unit 522 including digital switches S0 to S7, and resistors R0 to R7 connecting nodes N0 to N7 to ground voltage GND. Digital switches S0 to S7 constituting input unit 522 are connected between power supply voltage Vcc and nodes N0 to N7, respectively. Nodes N0 to N7 are connected to ground voltage GND through resistors R0 to R7, respectively.

  The potentials of nodes N0 to N7 are set to a logic high level in response to turning on of corresponding digital switches S0 to S7, and are set to a logic low level when corresponding digital switches S0 to S7 are turned off. Test input bits RB0-RB7 are set according to the voltage levels of nodes N0-N7. For example, the voltage conversion method in deterioration simulation calculation unit 540 is set by a combination of on / off inputs (ie, test inputs) to digital switches S0-S7, that is, combinations of test input bits RB0-RB7. The number of test input bits can be arbitrarily set depending on the number of digital switches.

  The deterioration simulation calculation unit 540 operates when the test execution bit RBs is at a high level (that is, when the test is executed), and performs digital calculation to convert the digital voltage Daf according to the voltage conversion method according to the test input bits RB0 to RB7. A digital voltage Dsm corresponding to the simulated voltage Vsm is generated. That is, the digital voltage Daf is composed of a digital signal of a plurality of bits (n bits, n: an integer of 2 or more) indicating the magnitude of the simulated voltage Vsm to be output.

  Here, voltage conversion of the air flow meter output voltage Vaf in the deterioration simulation calculation unit 540 will be described with reference to FIGS. 6 and 7.

  Referring to FIG. 6, characteristic line L1 shows a case where the air flow meter output voltage Vaf is output as it is as Vsm = Vaf, that is, the simulated voltage Vsm. On the other hand, on the characteristic lines L2a and L2b, the simulated voltage Vsm is generated by multiplying the input air flow meter output voltage Vaf and the coefficient k. For example, if the coefficient k is set to 0 <k <1.0 as in the characteristic line L2a, it is possible to simulate a state in which the output voltage with respect to the same intake air amount is reduced as the air flow meter 42 is aged. it can.

  On the other hand, depending on the type of deterioration abnormality, there may be a case where the output voltage Vaf increases with respect to the same intake air amount. Can be simulated.

  When the simulated voltage Vsm according to the characteristic lines L2a and L2b is generated to simulate the deterioration state of the air flow meter 42, the deterioration simulation calculation unit 540 sets the coefficient k according to the test input bits RB0 to RB7 indicating the test input. What is necessary is just to set it as the structure to set.

  Alternatively, as shown by the characteristic lines L3a and L3b in FIG. 7, the simulated voltage Vsm with respect to the air flow meter output voltage Vaf can be generated according to a predetermined nonlinear characteristic. In this case, a conversion curve table corresponding to the characteristic lines L3a and L3b is set in advance in the deterioration simulation calculation unit 540, and a simulation voltage Vsm corresponding to the air flow meter output voltage Vaf is generated according to the table. That's fine. In such a configuration, the deterioration simulation calculation unit 540 selects one of a plurality of characteristic lines (for example, characteristic lines L3a and L3b) according to test input bits RB0 to RB7 indicating test inputs. do it.

  Referring to FIG. 5 again, the latch circuit 550 latches the digital voltage Dsm output from the deterioration simulation calculation unit 540. The D / A converter 560 generates an analog voltage corresponding to the digital voltage Dsm held in the latch circuit 550 as the simulated voltage Vsm. The voltage output circuit 570 is configured by a voltage follower circuit using an operational amplifier similarly to the voltage input circuit 510, and impedance-converts the simulated voltage Vsm and outputs it to the wiring 504 to the engine ECU 300. Thus, a simulated voltage Vsm that simulates the deterioration state of the air flow meter 42 is input to the engine ECU 300 in place of the air flow meter output voltage Vaf.

  As a result, in failure diagnosis system 300 # shown in FIG. 2, instead of air flow meter output voltage Vaf corresponding to the actual intake air amount, simulated voltage Vsm corresponding to the output voltage from air flow meter 42 in the deteriorated state is determined. Input to the unit 304. Therefore, abnormality detection by failure diagnosis system 300 # is performed by setting a test input corresponding to a deterioration state requiring abnormality detection and monitoring whether determination flag Jaf is set to a value indicating abnormality detection. A test can be performed to check whether or not is performed normally.

  Therefore, the soundness of failure diagnosis system 300 # that automatically detects an output characteristic abnormality (for example, aged deterioration) of air flow meter 42 provided in engine 10 can be checked by a vehicle test using test apparatus 500.

  Furthermore, since the simulation voltage Vsm is generated by digital calculation, the degree of freedom of the output abnormal state that can be simulated (for example, aging deterioration of different patterns) is increased. The test effect of the diagnostic system can be enhanced. Also, the setting of the simulated voltage can be performed with high accuracy.

  In particular, by generating the simulated voltage Vsm by multiplying the air flow meter output voltage Vaf and the coefficient k, the aging deterioration state is simulated for a wide range of air flow meter output voltage Vaf, that is, a wide range of intake air amount, by simple calculation. it can.

  Although not shown, the test apparatus 500 automatically detects the occurrence of a hardware failure in the air flow meter 42 by monitoring whether the air flow meter output voltage Vaf is within a normal range, for example. Is also provided.

  Note that the components of the test apparatus 500 shown in FIG. 5 correspond to “pseudo-deterioration means” in the present invention. In the configuration shown in FIG. 5, the test input circuit 530 corresponds to the “test input unit” in the present invention, and the A / D converter 520 corresponds to the “first auxiliary conversion unit” in the present invention. The deterioration simulation calculation unit 540 corresponds to the “calculation unit” in the present invention, and the D / A converter 560 corresponds to the “second auxiliary conversion unit” in the present invention. Further, the voltage output circuit 570 corresponds to “signal output means” in the present invention.

  FIG. 8 shows a test method for the failure diagnosis system of air flow meter 42 by the test apparatus according to the embodiment of the present invention.

  Referring to FIG. 8, in step S100, it is determined whether or not the test is started by confirming whether or not there is an ON input to test start switch 505 based on test execution bit RBs.

  At the start of the test (when YES is determined in step S100), the air flow meter output voltage Vaf sent to the test apparatus 500 via the wiring 504 is A / D converted by the A / D converter 520, and the digital voltage Daf Is generated (step S110).

  In step S120, it is determined whether or not the A / D converted digital voltage Daf is within a normal range. When YES is determined in step S120, that is, when the airflow meter output voltage Vaf is within the normal range, the calculation content by the deterioration simulation calculation unit 540 is set by reading the test input (step S130). For example, the coefficient k shown in FIG. 6 is set according to the test input bits RB0 to RB7.

  In step S140, the deterioration simulation calculation unit 540 performs voltage conversion according to the test input read in step S130. For example, a digital operation of multiplying the coefficient k set in step S130 and the digital voltage Daf is executed to obtain the digital voltage Dsm.

  In step S150, it is determined whether the digital voltage Dsm calculated in step S140 is within the normal range. Thereby, it is confirmed whether or not the simulated voltage Vsm after conversion is within a normal range. If it is within the normal range (when YES is determined in step S150), the digital voltage Dsm is D / A converted to generate a simulated voltage Vsm (step S160). Furthermore, the generated simulated voltage Vsm is output from engine equipment 500 to engine ECU 300 via wiring 504 (step S170).

  In step S180, the engine ECU 300 performs a failure diagnosis of the air flow meter 42 based on the simulated voltage Vsm. In step S190, by confirming the determination result (that is, the determination flag Jaf in FIG. 2) in the engine ECU 300 on the test apparatus 500 side via the wiring 504, the aged deterioration state of the air flow meter 42 can be correctly detected as an abnormality. That is, whether or not failure diagnosis system 300 # is operating normally can be confirmed. Or in step S190, the display of the original diagnostic monitor in a vehicle can also be confirmed.

  It should be noted that, other than when the test is started (NO determination in step S100), when the air flow meter output voltage Vaf input to the test apparatus 500 is outside the normal range (NO determination in step S120), and after the simulated deterioration calculation If the simulated voltage Vsm is outside the normal range (NO determination in step S150), the test is not executed.

  In the flowchart shown in FIG. 8, step S190 corresponds to the “determination checking unit” in the present invention. Further, the function of the “pseudo-deteriorating means” in the present invention is realized by the operation of the test apparatus 500 (FIG. 5) according to the processing of steps S110 to S170.

  In the above-described embodiment, an example of a test apparatus for a failure diagnosis system relating to an output characteristic abnormality due to deterioration over time of an air flow meter provided in an engine (internal combustion engine) is illustrated. However, the present invention is applied to an air flow meter. It is not limited to a test apparatus for a failure diagnosis system. That is, for other sensors provided in the engine, characteristic lines (FIGS. 6 and 7) for simulating aging deterioration are created, and a simulation voltage is generated according to these characteristic lines in the deterioration simulation calculation unit. With this configuration, it is possible to similarly configure a test apparatus configured in the same manner as in FIG. 2 to check whether the failure diagnosis system for other sensors can detect the occurrence of output abnormality due to aging. Is possible.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a schematic block diagram of the engine system used as the test object of the test apparatus which concerns on embodiment of this invention. It is a schematic block diagram which shows the structure of the failure diagnosis system with which the engine system of FIG. 1 was equipped. It is a conceptual diagram explaining the output characteristic of an airflow meter. It is a conceptual diagram explaining the structure of the vehicle test using the test apparatus which concerns on embodiment of this invention. It is a block diagram explaining in detail the structure of the test apparatus shown in FIG. It is a 1st figure explaining conversion of the air flow meter output voltage in a test device. It is a 2nd figure explaining conversion of the air flow meter output voltage in a test device. It is a flowchart explaining the test method of the failure diagnosis system using the test apparatus which concerns on embodiment of this invention.

Explanation of symbols

  10 engine, 20 intake manifold, 30 surge tank, 40 intake duct, 42 air flow meter, 50 air cleaner, 60 electric motor, 70 throttle valve, 80 exhaust manifold, 90 three-way catalytic converter, 100 accelerator pedal, 110 cylinder, 120 fuel injection Injector, 160 Fuel distribution pipe, 170 Fuel pressure regulator, 180 Low pressure fuel pump, 190 Fuel filter, 200 Fuel tank, 300 Engine ECU, 300 # Fault diagnosis system, 302 Intake air amount estimation unit, 304 judgment unit, 305 Output characteristic line (Original characteristics of air flow meter), 307 Output characteristic line (when air flow meter deteriorates), 380 Water temperature sensor, 420 Air-fuel ratio sensor, 440 Accelerator opening sensor, 460 Rotation speed Sensor, 500 test device, 502,504 wiring, 505 test start switch, 510 voltage input circuit, 520 A / D converter, 530 test input circuit, 540 deterioration simulation operation unit, 550 latch circuit, 560 D / A converter, 570 Voltage output circuit, 1000 vehicle, Daf digital voltage (air flow meter output voltage), Dsm digital voltage (simulated voltage), Air air intake air amount estimated value, Jaf determination flag, k coefficient (for deterioration simulation calculation), L1 characteristic line, L2a, L2b, L3a, L3b Characteristic curve (deterioration simulation calculation), Qair measurement intake air amount, RB0-RB7 test input bit, RBs test execution bit, S0-S7 digital switch, Vaf airflow meter output voltage, Vaf # output voltage estimation Value, Vsm Simulated voltage.

Claims (7)

A test device for indicating whether or not a failure diagnosis system for an internal combustion engine functions normally,
The internal combustion engine measures the predetermined state quantity of the internal combustion engine and generates an output signal according to the measured state quantity, and based on the comparison between the output signal and the operating state of the internal combustion engine, And a control device configured to perform failure diagnosis of the measuring device,
The test apparatus comprises:
A pseudo-deterioration means that receives an output signal from the measuring device, converts it into an output signal that simulates the deterioration state of the measuring device, and outputs it;
Determination confirmation means for confirming whether or not failure detection has been performed by the control device,
At the time of a test, the control device performs a failure diagnosis of the measurement device based on a comparison between an output signal converted by the pseudo deterioration means and an operating state of the internal combustion engine. The pseudo deterioration means is
A test input means for receiving a test input;
A signal converting means for converting an output signal from the measuring device according to the test input to the test input means;
The test apparatus according to claim 1, further comprising: a signal output unit that sends the output signal converted by the signal conversion unit to the control device.   The test apparatus according to claim 1, wherein the signal conversion unit converts the output signal by multiplying a coefficient determined by the test input by an output signal from the measurement apparatus. The output signal from the measuring device is an analog voltage,
The signal converting means includes
First auxiliary conversion means for converting an output signal from the measuring device into a first digital signal;
Computing means for performing a predetermined computation between the first digital signal from the first auxiliary means and the digital signal corresponding to the test input;
Second auxiliary conversion means for converting the calculation result obtained by the calculation means into an analog voltage;
The test apparatus according to claim 1, wherein the signal output unit receives the analog voltage from the second auxiliary conversion unit as an output signal converted by the signal conversion unit.   The test apparatus according to any one of claims 1 to 4, wherein the failure diagnosis by the control apparatus relates to exhaust emission from the internal combustion engine.   The test apparatus according to claim 1, wherein the measurement apparatus is an air flow meter that measures an intake air amount to the internal combustion engine.   A vehicle produced using the test apparatus according to claim 1.

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