JP3750201B2 - Exhaust gas recirculation apparatus failure diagnosis method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and apparatus for diagnosing a failure of an exhaust gas recirculation device for an engine mounted on a vehicle in a factory or the like.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open No. Hei 6-58210, in an engine in which an exhaust gas recirculation control valve for opening and closing this passage is provided in an exhaust gas recirculation passage that connects the exhaust passage and the intake passage of the engine, During operation, the exhaust gas recirculation control valve is temporarily opened and closed, and it is detected whether the pressure fluctuation in the intake passage or the exhaust gas recirculation valve before and after the opening / closing is within a predetermined range. A failure diagnosis method for an exhaust gas recirculation apparatus that determines whether or not a recirculation system has failed is known.
[0003]
According to this device, when a failure that does not activate the exhaust gas recirculation control valve occurs, the pressure fluctuation does not occur, so that the failure is determined during engine operation.
[0004]
[Problems to be solved by the invention]
By the way, the failure diagnosis device shown in the above publication is for diagnosing a failure of the exhaust gas recirculation device during normal traveling, but also diagnoses a failure of the exhaust gas recirculation device even in an inspection at the time of shipment at a manufacturing factory. Is required. In this case, it is desirable to perform failure diagnosis easily and efficiently using an external inspection device installed in a factory or the like. In the exhaust gas recirculation device, the exhaust gas recirculation control valve includes a valve body and a pressure type actuator that operates the valve body, and the driving means includes a negative pressure introduction solenoid valve and an atmospheric pressure introduction solenoid valve for the pressure type actuator. Therefore, it is required to determine various failures such as malfunction of these valves.
[0005]
Japanese Patent Publication No. 7-18776 discloses a first diagnostic program executed in a normal mode and a test as a device in which an in-vehicle control unit self-diagnose an abnormality in sensor output, actuator operation or computer processing. The storage means stores the second self-diagnosis program executed in the mode and the display program, and executes one of the three programs according to the switching operation of the test switch and the energizing switch. It is shown. According to this device, a test mode can be selected in a repair shop or the like. However, this publication only shows a failure diagnosis of a general control system including a control unit and sensors and actuators connected to the control unit, and shows an effective method for failure diagnosis of the exhaust gas recirculation device. Absent.
[0006]
In view of the above circumstances, the present invention provides an exhaust gas recirculation apparatus failure diagnosis method and apparatus capable of easily and efficiently diagnosing an exhaust gas recirculation apparatus failure at the time of inspection at a factory or the like. Objective.
[0007]
[Means for Solving the Problems]
  According to the failure diagnosis method of the present invention, an exhaust gas recirculation passage that connects an exhaust passage and an intake passage of an engine, an exhaust gas recirculation control valve that is provided in the exhaust gas recirculation passage and adjusts an exhaust gas recirculation amount, and an electric signal Driving means for driving the exhaust gas recirculation control valve and operation of the exhaust gas recirculation control valvepositionAnd a control unit connected to the drive unit and the detection unit.The exhaust gas recirculation control valve is composed of a valve body and a pressure type actuator that operates the valve body, and the driving means is composed of a negative pressure introducing solenoid valve and an atmospheric pressure introducing solenoid valve for the pressure type actuator, These solenoid valves adjust the introduction ratio of negative pressure and atmospheric pressure to the actuator, and the opening degree of the exhaust gas recirculation control valve increases as the negative pressure introduction ratio increases.A method of diagnosing a failure of an exhaust gas recirculation device, by transmitting a test drive command signal from an external test device to the control unit, A first control state in which the solenoid valves are feedback-controlled so that the exhaust recirculation control valve is opened from a predetermined initial state to a predetermined opening larger than this, and then the opening of the exhaust recirculation control valve is set to A second control state in which both the solenoid valves are closed to keep them constant, and a third control state in which the atmospheric pressure introduction solenoid valve is opened to return the exhaust gas recirculation control valve to the initial state. The drive means is controlled so as to shift sequentially, and the first 1 Thru Three In each of the control states, the detection means detects the operating position of the exhaust gas recirculation control valve, and the test device receives an output indicating the detected value from the control unit. Detects disconnections and shorts between the solenoid valve for pressure introduction and the solenoid valve for atmospheric pressure introductionIs.
[0008]
According to this method, when a vehicle is inspected at a factory or the like, the drive means for the test is automatically controlled by transmitting a command signal from a test apparatus installed at an inspection place or the like. In both cases, based on the output of the detection means transmitted to the test device, it is determined that the exhaust gas recirculation device has failed when the value is not within the proper range.
[0011]
  In particular,It is possible to discriminate various failures such as disconnection or short circuit of the circuit energizing the atmospheric pressure introduction solenoid valve, or disconnection or short circuit of the circuit energizing the negative pressure introduction solenoid valve.
[0012]
In the above method, the output of the engine speed detection means before and after the control for operating the exhaust gas recirculation control valve is received from the control unit by the test device, and the output of the engine speed detection means before and after this control is received. It is preferable to determine whether or not the exhaust gas recirculation device has failed based on whether or not the change is equal to or less than a predetermined value.
[0013]
In this way, when the exhaust gas recirculation is normally performed, the engine speed changes by a predetermined value or more. However, the exhaust gas recirculation may be caused by a malfunction such as an exhaust gas recirculation control valve malfunction, an exhaust gas recirculation passage leak, or a pipe disconnection. If not, such a failure is determined because the engine speed hardly changes.
[0015]
The control of the drive means by the drive command signal and the determination of the failure are preferably performed when the engine is in an idle state. In this way, failure diagnosis is effectively performed in an idle state corresponding to a state where the engine is operated and placed at an inspection place or the like.
[0016]
  Further, the failure diagnosis apparatus used in the above method includes an exhaust gas recirculation passage that connects the exhaust passage and the intake passage of the engine, an exhaust gas recirculation control valve that is provided in the exhaust gas recirculation passage and adjusts an exhaust gas recirculation amount, Driving means for driving the exhaust gas recirculation control valve according to a signal, and operation of the exhaust gas recirculation control valvepositionAnd a control unit connected to the drive unit and the detection unit.The exhaust gas recirculation control valve is composed of a valve body and a pressure type actuator that operates the valve body, and the driving means is composed of a negative pressure introducing solenoid valve and an atmospheric pressure introducing solenoid valve for the pressure type actuator, These solenoid valves adjust the introduction ratio of negative pressure and atmospheric pressure to the actuator, and the opening degree of the exhaust gas recirculation control valve increases as the negative pressure introduction ratio increases.A device for diagnosing a failure of the exhaust gas recirculation device, comprising an external test device connected to the control unit via a test terminal,thisExhaust gas recirculation based on the operating state of transmission / reception means for transmitting a test drive command signal to the control unit and receiving the output of the detection means, and the exhaust gas recirculation control valve checked by the output of the detection means. And a failure determination means for determining the failure of the device.The control unit performs feedback control of the solenoid valves so as to open the exhaust gas recirculation control valve from a predetermined initial state to a predetermined opening larger than the predetermined value in response to a drive command signal from the test device. A second control state in which both the solenoid valves are closed to keep the opening of the exhaust gas recirculation control valve constant, and the exhaust gas recirculation control valve to be returned to the initial state. Test control means for controlling the drive means to sequentially shift to the third control state in which the atmospheric pressure introduction solenoid valve is opened is provided, while the failure determination means of the test device is provided with the first control state. 1 Thru Three In each of the control states, the detection means detects the operating position of the exhaust gas recirculation control valve, receives an output indicating the detected value from the control unit, and based on the detected value, the negative pressure introducing solenoid Configured to detect disconnection and short circuit of the valve and solenoid valve for introducing atmospheric pressureIs.
[0017]
According to this apparatus, the above-described failure diagnosis method is automatically executed at the time of inspection in a factory or the like, and the failure diagnosis of the exhaust gas recirculation device is easily performed.
[0019]
Further, the engine speed detection means for detecting the engine speed is connected to the control section, and the output of the engine speed detection means before and after the control for operating the exhaust gas recirculation control valve is received from the control section. It is preferable that the failure determination means has a function of determining whether or not the exhaust gas recirculation device has failed depending on whether or not the change in the output of the engine speed detection means before and after is not more than a predetermined value.
[0021]
In the failure diagnosis apparatus as described above, an idle determination means for determining the engine idle state is provided in the engine control unit, and control according to the drive command signal is performed only when the idle state is determined by the idle determination means. Preferably, the control unit is configured to do so.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a schematic structure of an entire engine equipped with an exhaust gas recirculation device to which the present invention is applied. In this figure, reference numeral 1 denotes an engine body having a cylinder, and an intake port 3 opened and closed by an intake valve and an exhaust port 4 opened and closed by an exhaust valve are opened in a combustion chamber 2 of the cylinder. An intake passage 5 is connected to the intake port 3, and an exhaust passage 11 is connected to the exhaust port 4.
[0023]
In the intake passage 5, an air cleaner 6, an air flow sensor 7, a throttle valve 8, and a surge tank 9 are provided in that order from the upstream side, and an injector 10 for injecting fuel is provided in the vicinity of the intake port 5. On the other hand, the exhaust passage 11 is provided with a catalyst device 12 or the like. An idle switch 13 and an engine speed sensor 14 are provided in the intake passage 5 and the engine body 1, respectively.
[0024]
Further, an EGR passage (exhaust gas recirculation passage) 15 communicating with the exhaust passage 11 is connected to the surge tank 9 in the middle of the intake passage 5, for example, and an EGR valve (exhaust gas) for adjusting the exhaust gas recirculation amount is connected to the EGR passage 15. A reflux control valve) 16 is provided.
[0025]
The EGR valve 16 includes a housing 17 provided in the EGR passage 15, a valve body 18 installed in the housing 17, and a pressure actuator 19 that drives the valve body 18. The actuator 19 is connected to an operating pressure introduction passage 20 in which a negative pressure passage 21 and an atmospheric pressure passage 22 are joined. The negative pressure passage 21 is connected to the intake passage 5 downstream of the throttle valve 8. The atmospheric pressure passage 22 is connected to the intake passage 5 upstream of the throttle valve 8.
[0026]
The negative pressure passage 21 is provided with a negative pressure introducing solenoid valve 23, and the atmospheric pressure passage 22 is provided with an atmospheric pressure introducing solenoid valve 24, and the EGR valve 16 is connected by these solenoid valves 23, 24. Driving means for driving is configured. The solenoid valves 23 and 24 are duty controlled to adjust the introduction ratio of the negative pressure and the atmospheric pressure to the actuator 19, and the opening degree of the EGR valve 16 is adjusted accordingly. Specifically, when the pressure introduced into the actuator 19 is atmospheric pressure, the valve body 18 of the EGR valve 16 is fully closed, and the valve body of the EGR valve 16 increases as the negative pressure introduction ratio increases with respect to the actuator 19. It is comprised so that the opening degree of 18 may become large.
[0027]
The EGR valve 16 is provided with a position sensor (detection means) 25 for detecting its operating position (opening degree).
[0028]
The solenoid valve valves 23 and 24 and the position sensor 25 are connected to an engine control unit (ECU) 30 as a control unit, and the air flow meter 7, idle switch 13, engine speed sensor 14 and the like are also connected to the engine control unit 30. It is connected. The operation state of the EGR valve 16 is controlled by a duty signal output from the engine control unit 30 to each solenoid valve 23, 24. For example, when the EGR valve 16 is in an operation region where EGR is to be performed during normal operation, the position sensor The solenoid valves 23 and 24 are duty-controlled according to the deviation between the detected value by 25 and the target value, so that the operating position of the EGR valve 16 is feedback-controlled.
[0029]
The control unit 30 has a test terminal 31 and can be connected to an external test apparatus 41 via a coupler 42 in a state where the control unit 30 is mounted on an automobile 40 as shown in FIG. The test apparatus 41 is installed at a predetermined location in the factory for engine inspection at the time of shipment at a vehicle manufacturing factory, for example, and a display means 43 is attached to the test apparatus 41.
[0030]
FIG. 3 shows functional configurations of the engine control unit 30 and the test apparatus 41. The engine control unit 30 performs EGR control during normal operation as described above and other various engine controls, and also performs control for failure diagnosis of the exhaust gas recirculation device by the test device 41. Control means 32 is provided. Further, the engine control unit 30 includes a signal input / output unit 33 for inputting / outputting various detection signals and the like, an idle determination unit 34 for determining an idle state of the engine, and the like.
[0031]
The test drive control means 32 receives a drive command signal from the test device 41, and executes a test mode when the idle determination means 34 determines that it is in an idle state. In the first control state in which both the solenoid valves 23 and 24 are controlled so as to open the EGR valve 16 from a predetermined initial state to a predetermined opening larger than this in accordance with the drive command signal, A second control state in which the solenoid valves 23 and 24 are closed to keep the opening of the EGR valve 16 constant, and the solenoid valves 23 and 24 are turned back to return the EGR valve 16 to an initial state. The mode is sequentially shifted to the third control state to be controlled.
[0032]
In addition, when the test mode is executed, the signal input / output means 33 transmits the EGR valve operating position input from the position sensor 25 to the test device 41 in response to a request from the test device 41, and further, the test mode Signals input from the engine speed sensor 14 before and after the control are also transmitted to the test apparatus.
[0033]
On the other hand, the test apparatus 41 is provided with transmission / reception means 44 and failure determination means 45. The transmission / reception means 44 transmits a test drive command signal to the engine control unit 30 and transmits a signal of an EGR valve operating position to the engine control unit 30 during each control period in the test mode. This signal is requested and received, and the engine speed signal before and after the control in the test mode is also received.
[0034]
Further, the failure determination means 45 determines a failure based on the operating state of the EGR valve 16, specifically, whether or not the EGR valve operating position is within an appropriate range in each of the first to third control states. By checking whether or not, it is determined whether it is normal or failure. The display means 43 attached to the test apparatus 41 displays the failure when the failure of the exhaust gas recirculation device is determined by the determination means 45.
[0035]
A failure diagnosis method performed by the test apparatus 41 and the engine control unit 30 will be described with reference to a flowchart of FIG. 4 while referring to a time chart of FIG.
[0036]
When the engine control unit 30 and the test apparatus 41 are connected at the time of shipment at an automobile manufacturing factory or the like, an input operation for starting a failure diagnosis of the exhaust gas recirculation apparatus is performed on the test apparatus 41 side. First, the test apparatus 41 transmits an EGR test mode start command (test drive command signal) to the engine control unit 30 in step S1. When the engine control unit 30 receives the EGR test mode start command in step S101, the engine control unit 30 checks in step S102 whether or not the engine is in an idle state based on signals from the idle switch 13, the engine speed sensor 14, and the like. If it is not in the idle state, the test is terminated in step S103 and the process is terminated. If it is in the idle state, the processes in and after step S104 are performed.
[0037]
In step S104, execution of the EGR position F / B mode is started. In this mode, feedback control is performed so that the EGR valve 16 is opened from the initial state (the previous state) to a predetermined opening larger than this. That is, as shown in FIG. 5A, the EGR valve position is a small value, for example, the EGR valve fully closed position until the test mode start time t0, but the EGR immediately after the test mode start time t0. Feedback control is performed after the target value of the valve position (EGR position) is increased by a predetermined amount.
[0038]
The test apparatus 41 waits for the set time TA1 to elapse in step S2 after sending the test mode start command, and when the set time TA1 has passed (at time t1 in FIG. 5A), sends a request for EGR position value transmission. In response to this, the engine control unit 30 transmits the EGR position value P1 detected by the position sensor 25 to the test apparatus 41 in step S105.
[0039]
The test device 41 reads the EGR position value P1 transmitted from the engine control unit 30 in step S3, and determines whether or not the EGR position value P1 is within a predetermined range in step S4.
[0040]
On the other hand, the engine control unit 30 maintains the EGR position F / B mode until the set time TB1 elapses, but when the elapse of the time TB1 is confirmed in step S106 (time t2 in FIG. 5A). From step S107, execution of the EGR position holding mode is started in step S107. In this mode, the negative pressure introduction solenoid valve 23 and the atmospheric pressure introduction solenoid valve 24 are both closed so that the operating pressure in the actuator 19 of the EGR valve 16 can be contained, whereby the EGR valve 16 can be closed. The same opening degree is maintained.
[0041]
In the test apparatus 41, when it is confirmed in step S4 that the EGR position value P1 is within the predetermined range, the set time TA2 is waited for in step S5 and the set time TA2 has elapsed (in FIG. 5A). The engine control unit 30 transmits an EGR position value P2 detected by the position sensor 25 to the test device 41 in step S108 in response to a request for transmission of the EGR position value at time t3).
[0042]
The test device 41 reads the EGR position value P2 transmitted from the engine control unit 30 in step S6, and determines whether or not the EGR position value P2 is within a predetermined range in step S7.
[0043]
On the other hand, the engine control unit 30 continues the EGR position holding mode until the set time TB2 elapses, but when the elapse of time TB2 is confirmed in step S109 (time t4 in FIG. 5A). In step S110, execution of the EGR test mode is terminated. At this time, the EGR valve 16 is returned to the initial state by opening the atmospheric pressure introduction solenoid valve 24. That is, as shown in FIG. 5A, the EGR valve position is returned to the original small value after time t4.
[0044]
When it is confirmed in step S7 that the EGR position value P2 is within the predetermined range in the test apparatus 41, the set time TA3 is waited for in step S8 and the set time TA3 has elapsed (in FIG. 5A). The engine control unit 30 transmits the EGR position value P3 detected by the position sensor 25 to the test device 41 in step S111 in response to a request for EGR position value transmission at time t5).
[0045]
The test device 41 reads the EGR position value P3 transmitted from the engine control unit 30 in step S9, and determines whether or not the EGR position value P3 is within a predetermined range in step S10.
[0046]
If it is confirmed that the EGR position value P3 is within the predetermined range, it is further determined in step S11 whether or not the engine speed Ne has changed more than a predetermined value before and after the test.
[0047]
The test apparatus 41 determines whether it is a failure or normal according to the determinations of steps S4, S7, S10, and S11. That is, if the EGR position value is not within the predetermined range in any one of the determinations in steps S4, S7, and S10, or if the engine speed has not changed more than the predetermined value in the determination in step S11, step S12 is performed. It is determined that a failure has occurred, and the display unit 41 displays the failure. Further, if the EGR position value is within the predetermined range in each determination in steps S4, S7, and S10, and if the engine speed has changed by a predetermined value or more in the determination in step S11, the normal operation is performed in step S13. Is determined.
[0048]
Note that the time t1 in FIG. 5 is slightly later than the time t2 after the time t0, the time t3 is slightly later than the time t4 after the time t2, and the time t5 is somewhat later than the time t4. Set times TA1, TA2, TA3 and TB1, TB2 are determined.
[0049]
According to the method as described above, failure diagnosis of the EGR device is easily and effectively performed at the time of shipping inspection at a manufacturing factory.
[0050]
That is, when the engine is operated and placed in the inspection place in the inspection process at the time of shipment, the engine is in an idle state, and if there is a command from the test apparatus 41 in the idle state, the EGR test mode is automatically activated. . Then, the EGR position F / B mode and the EGR position holding mode are sequentially executed for the set time and then the test mode is automatically terminated, and the EGR position F / B mode and the EGR position holding mode are in progress. After the test mode is output, EGR positions P1, P2, and P3 are transmitted from the engine control unit 30 to the test apparatus 41 in response to a transmission request. The test apparatus 41 performs various operations based on these EGR positions P1, P2, P3, and the like. A failure is determined.
[0051]
Specifically, how the EGR position change pattern during the EGR test mode changes due to various failures is compared with the normal pattern shown in FIG. 5 (a) using FIGS. 5 (b) to 5 (e). However, it will be explained. In this embodiment, the negative pressure introducing solenoid valve 23 is normally closed (closed when not energized), and the atmospheric pressure introducing solenoid valve 24 is normally open (open when deenergized).
[0052]
When the energization circuit for the atmospheric pressure introduction solenoid valve 24 is disconnected in the EGR valve drive system, the solenoid valve 24 remains open regardless of the control signal. In the case of such a failure, EGR during the test mode is maintained. The position change is as shown in FIG.
[0053]
That is, in this case, the atmosphere introduction side cannot be controlled, but the atmospheric pressure passage 22 has a relatively small passage area and the air flow is restricted to some extent. If the negative pressure introduction amount from the negative pressure passage 21 is large, the EGR valve 16 is opened. In the EGR position F / B mode, the negative pressure introduction solenoid valve 23 is feedback-controlled to open the EGR valve 16 to a predetermined opening, and the EGR position P1 examined in this mode is Within the appropriate range. However, when shifting to the EGR position holding mode, control is performed so that both the solenoid valves 23 and 24 are closed. However, since the atmospheric pressure introduction solenoid valve 24 is not actually closed, the negative pressure in the actuator 19 is reduced. It is discharged and the EGR valve 16 is closed.
[0054]
Therefore, in this case, the EGR position change after time t2 when the mode is switched to the EGR position holding mode is different from the normal time, and the EGR position P2 ′ checked during the EGR position holding mode is out of the proper range (NO in step S7). Thus, the failure is determined.
[0055]
When the energization circuit for the atmospheric pressure introduction solenoid valve 24 is short-circuited, the solenoid valve 24 is closed regardless of the control signal. In such a failure, the EGR position change during the test mode is shown in FIG. c).
[0056]
That is, in the EGR position F / B mode, the negative pressure introduction solenoid valve 23 is feedback-controlled to open the EGR valve 16 to a predetermined opening, and in the EGR position holding mode, the negative pressure introduction solenoid valve 23 is opened. Is closed and the atmospheric pressure introduction solenoid valve 24 is already closed, so that the EGR valve operating position up to that point is maintained. Therefore, the EGR positions P1 and P2 at these stages are within an appropriate range. However, even if control is performed to open the atmospheric pressure introduction solenoid valve 24 at the end of the EGR test mode, the valve 24 remains closed, and the EGR valve 16 is kept at a large opening as in the EGR position holding mode. Be drunk.
[0057]
Therefore, in this case, the EGR position change after the end of the EGR test mode t4 is different from the normal time, and the EGR position P3 ′ to be examined after the end of the EGR test mode is out of the appropriate range (step S10 is NO). A failure is determined.
[0058]
When the energization circuit for the negative pressure introducing solenoid valve 23 is disconnected, the valve 23 is closed regardless of the control signal. In such a failure, the EGR position change during the test mode is shown in FIG. )become that way.
[0059]
That is, even if the EGR position F / B mode is set, the negative pressure introduction solenoid valve 23 does not open, so that no negative pressure is introduced into the actuator, and thus the EGR valve 16 is kept closed. Accordingly, at this stage, the EGR position P1 'is out of the proper range (step S4 is NO), and thus a failure is determined.
[0060]
When the energization circuit for the negative pressure introducing solenoid valve 23 is short-circuited, the valve 23 is opened regardless of the control signal. In the case of such a failure, since a negative pressure is always introduced to the actuator 19 of the EGR valve 16, the opening degree of the EGR valve 16 increases from the beginning as shown in FIG. When it is determined that the EGR position is larger than the appropriate range, a failure is determined.
[0061]
In this way, it is possible to determine all the various failures due to disconnection, short-circuiting, etc. of the solenoid valves 23 and 24 in the drive system of the EGR valve 16.
[0062]
Furthermore, in this embodiment, it is checked whether or not the engine speed has changed by a predetermined value or more before and after the test (step S11), and this makes it possible to determine failures other than the drive system of the EGR valve 16. That is, if normal, the exhaust gas recirculates to the intake system by the control during the test mode, and the engine speed changes before and after the test, but the exhaust gas does not recirculate due to a failure. In this case, the engine speed hardly changes before and after the test. Even if the EGR valve 16 is normally driven, the exhaust gas is not recirculated when there is a failure such as leakage or disconnection of the piping in the EGR passage 15 or the housing 17 of the EGR valve 16. Sometimes.
[0063]
Therefore, in addition to checking the EGR position at each stage of the test mode, it is possible to discriminate various types of failures in the EGR system by checking the engine speed change before and after the test.
[0064]
In addition, according to the failure diagnosis method as described above, since it is possible to determine the type of failure in addition to the determination of the presence or absence of failure, for example, when determining the failure in step S12 and displaying this, If the type is displayed, it is convenient for repair.
[0065]
In the above embodiment, both the failure determination by examining the EGR position at each stage of the test mode and the failure determination by examining the engine speed change before and after the test are performed. Even if only one of the above is performed, a considerable failure can be determined.
[0066]
The method and apparatus of the present invention can be applied not only to inspection at the time of shipment at a manufacturing factory but also to inspection diagnosis at a repair factory or the like.
[0067]
【The invention's effect】
The method and apparatus of the present invention includes an exhaust passage, an exhaust gas recirculation control valve, drive means for driving the exhaust gas recirculation control valve, detection means for detecting the operating state of the exhaust gas recirculation control valve, and a control unit. For the device, an external test device is connected to the control unit, and the drive means is controlled to operate the exhaust gas recirculation control valve in a predetermined state by a drive command signal transmitted from the test device, Since the test device receives the output of the detection means and determines the failure based on the operating state of the exhaust gas recirculation control valve investigated by this, the exhaust gas recirculation control valve of the exhaust gas recirculation control valve is inspected at a factory or the like. It is possible to easily and properly diagnose a failure of a drive system or the like.
[0068]
  In particular,The exhaust recirculation control valve driving means comprises a negative pressure introducing solenoid valve and an atmospheric pressure introducing solenoid valve,These solenoid valves adjust the introduction rate of negative pressure and atmospheric pressure to the actuator, and diagnose the failure of the exhaust gas recirculation device configured so that the opening degree of the exhaust gas recirculation control valve increases as the negative pressure introduction rate increases To doAs the control based on the drive command signal, both the solenoid valves are opened so that the exhaust gas recirculation control valve is opened from a predetermined initial state to a predetermined opening larger than this.feedbackThe first control state to be controlled, and then the two solenoid valves to keep the opening of the exhaust gas recirculation control valve constant.BothThe second control state to be closed, and the exhaust recirculation control valve to return to the initial stateOpen the solenoid valve for introducing atmospheric pressureTransition to the third control state sequentially, and determine the failure based on the output of the detection means in each control stateBy doingIt is possible to effectively determine various failures of the drive means composed of both the solenoid valves.
[0069]
  In addition to the above-described failure determination based on the output of the detection means for detecting the operating state of the exhaust gas recirculation control valve., ExhaustThe output of the engine speed detecting means before and after the control for operating the air reflux control valve is received from the control unit by the test device, and the failure is determined based on the change in the output of the engine speed detecting means before and after the control. By doing so, in addition to the failure of the drive system of the exhaust gas recirculation control valve, it is also possible to discriminate failures such as leaks in the exhaust gas recirculation passage and disconnection of piping.
[Brief description of the drawings]
FIG. 1 is a schematic view showing an example of an engine equipped with an EGR device to which the method and apparatus of the present invention are applied.
FIG. 2 is a schematic diagram showing a connection relationship between an engine control unit and an external test apparatus.
FIG. 3 is a functional block diagram of a part constituting the failure diagnosis apparatus.
FIG. 4 is a flowchart illustrating an example of a failure diagnosis method.
FIGS. 5A and 5B are time charts showing changes in the position of the EGR valve accompanying execution of the EGR test mode, where FIG. 5A shows a normal case and FIGS. 5B to 8E show cases where various failures occur;
[Explanation of symbols]
5 Intake passage
11 Exhaust passage
13 Idle switch
14 Engine speed sensor
15 EGR passage
16 EGR valve
19 Actuator
23 Solenoid valve for introducing negative pressure
24 Solenoid valve for introducing atmospheric pressure
25 Position sensor
30 Engine control unit
32 Test drive control means
34 Idle determination means
41 Test equipment
44 Transmission / reception means
45 Failure determination means

Claims (6)

An exhaust gas recirculation passage that connects the exhaust passage and the intake air passage of the engine, an exhaust gas recirculation control valve that is provided in the exhaust gas recirculation passage and adjusts an exhaust gas recirculation amount, and drives the exhaust gas recirculation control valve according to an electric signal A pressure means that includes a drive means, a detection means for detecting an operating position of the exhaust gas recirculation control valve, and a control unit connected to the drive means and the detection means, wherein the exhaust gas recirculation control valve operates the valve body and the valve body; An actuator, and the driving means is composed of a solenoid valve for introducing a negative pressure and a solenoid valve for introducing an atmospheric pressure for the pressure actuator, and the introduction ratio of the negative pressure and the atmospheric pressure to the actuator by these solenoid valves. There is adjusted, because the configured exhaust gas recirculation system so that the opening of the exhaust gas recirculation control valve as a negative pressure introduction ratio is increased increases A method for diagnosing,
By sending a test drive command signal from an external test device to the control unit, both the solenoid valves are fed back so as to open the exhaust gas recirculation control valve from a predetermined initial state to a predetermined opening larger than this. A first control state to be controlled, a second control state in which both the solenoid valves are closed in order to maintain a constant opening of the exhaust gas recirculation control valve, and an initial state of the exhaust gas recirculation control valve. To control the driving means to sequentially shift to the third control state of opening the atmospheric pressure introduction solenoid valve so as to return to
Respectively, in each control state of the first to third, receives an output indicating the detection value by detecting the operating position of the exhaust gas recirculation control valve from the control unit by the test device by the detection means, these detection A fault diagnosis method for an exhaust gas recirculation device, wherein the disconnection and the short circuit of the solenoid valve for introducing negative pressure and the solenoid valve for introducing atmospheric pressure are determined based on values . The output of the engine speed detecting means before and after the control for operating the exhaust gas recirculation control valve is received from the control unit by the test device, and whether or not the change in the output of the engine speed detecting means before and after the control is below a predetermined value. 2. The exhaust gas recirculation apparatus failure diagnosis method according to claim 1, wherein whether or not the exhaust gas recirculation apparatus is malfunctioning is determined . 3. The failure diagnosis method according to claim 1, wherein when the engine is in an idle state, the drive means is controlled by the drive command signal and the failure is determined . An exhaust gas recirculation passage that connects the exhaust passage and the intake air passage of the engine, an exhaust gas recirculation control valve that is provided in the exhaust gas recirculation passage and adjusts an exhaust gas recirculation amount, and drives the exhaust gas recirculation control valve according to an electric signal A pressure means that includes a drive means, a detection means for detecting an operating position of the exhaust gas recirculation control valve, and a control unit connected to the drive means and the detection means, wherein the exhaust gas recirculation control valve operates the valve body and the valve body; An actuator, and the drive means comprises a solenoid valve for introducing negative pressure and a solenoid valve for introducing atmospheric pressure for the pressure actuator, and the introduction ratio of the negative pressure and the atmospheric pressure to the actuator by these solenoid valves. Because the exhaust gas recirculation device is configured such that the opening degree of the exhaust gas recirculation control valve increases as the negative pressure introduction ratio increases. There is provided an apparatus for diagnosing,
  An external test device connected to the control unit via a test terminal, and the test device includes transmission / reception means for transmitting a test drive command signal to the control unit and receiving the output of the detection means; A failure determining means for determining a failure of the exhaust gas recirculation device based on an operating state of the exhaust gas recirculation control valve checked by the output of the detection means,
  A first feedback control is performed on the two solenoid valves so that the exhaust gas recirculation control valve is opened from a predetermined initial state to a predetermined opening larger than this in response to a drive command signal from the test device. A control state, a second control state in which both the solenoid valves are closed in order to keep the opening degree of the exhaust gas recirculation control valve constant, and the exhaust gas recirculation control valve to return to the initial state. While providing a test control means for controlling the drive means so as to sequentially shift to a third control state in which the atmospheric pressure introduction solenoid valve is opened,
  The failure determination means of the test device is the first 1 Thru Three In each of the control states, the detection means detects the operating position of the exhaust gas recirculation control valve, receives an output indicating the detected value from the control unit, and based on the detected value, the negative pressure introducing solenoid Valves and A fault diagnosis device for an exhaust gas recirculation device, characterized in that each disconnection or short circuit of an atmospheric pressure introduction solenoid valve is discriminated. The engine speed detecting means for detecting the engine speed is connected to the control section, and the output of the engine speed detecting means before and after the control for operating the exhaust gas recirculation control valve is received from the control section. 5. The exhaust gas recirculation according to claim 4, wherein the failure discrimination means has a function of discriminating whether or not the exhaust gas recirculation device is malfunctioning based on whether or not the change in the output of the engine speed detection means is less than a predetermined value. Device fault diagnosis device. The engine control unit is provided with idle determination means for determining the engine idle state, and the control unit is configured to perform control according to the drive command signal only when the idle determination is determined by the idle determination unit. The fault diagnosis device for an exhaust gas recirculation device according to claim 4 or 5.

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