JP2016114109A - Failure diagnosis device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a failure diagnosis device which can prevent a wrong diagnosis in which an automatic transmission is diagnosed as failed even when the automatic transmission is not failed, when gear shift fails due to some mechanical trouble.SOLUTION: A failure diagnosis device for diagnosing whether or not an automatic transmission 4 is failed includes: a gear shift determination unit 52 for determining whether or not an automatic transmission 4 is changed to a required shift stage, after the start of gear shift; a failure determination calculation unit 53 for, in the case where the gear shift determination unit 52 has determined that it is not changed to the required shift stage, adding a first predetermined value Kto a failure determination value Kc, and, in the case where the gear shift determination unit 52 has determined that it is changed to the required shift stage, for subtracting a second predetermined value Kfrom the failure determination value Kc; and a failure diagnosis unit 54. On condition that a calculation failure determination value Kx calculated by the failure determination calculation unit 53 is equal to or greater than a predetermined failure diagnosis threshold value S, it is diagnosed that the automatic transmission 4 has been failed.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a failure diagnosis device that diagnoses a failure of an automatic transmission in which a shift operation of a manual transmission is automated.

Conventionally, as this type of failure diagnosis device, the failure of the switching actuator is determined based on the count value of the number of executions when the retry operation of the gear change operation of the automatic transmission continues and the operation amount of the change actuator at the time of gear change. What is diagnosed is proposed in Patent Document 1.
The failure diagnosis apparatus described in Patent Literature 1 diagnoses that the switching actuator is broken when the count value of the number of executions when the retry operation is continued reaches a predetermined number.

  When the operation amount of the switching actuator is less than a preset setting value, the failure diagnosis device adds a count value of the number of times of performing the retry operation, and when the operation amount of the switching actuator is equal to or more than the preset setting value. Does not add this count value. As a result, it is determined whether the automatic transmission has a gear meshing failure or a switching actuator has failed, thereby preventing erroneous diagnosis.

Japanese Unexamined Patent Publication No. 03-0779860

  However, in the fault diagnosis device described in Patent Document 1, the transmission may fail continuously due to mechanical interference of the switching actuator, that is, the retry operation described above may continue. In the failure diagnosis apparatus described in Patent Document 1, the count value of the number of executions of the retry operation may be added due to such a rare shift failure. As a result, since the automatic transmission is diagnosed as having a failure even though it has not failed, there is a problem that the prevention of the erroneous diagnosis is not sufficient.

  The present invention has been made in order to solve the above-described problems. When a gear shift fails due to some mechanical trouble, the automatic transmission is not malfunctioning. It is an object of the present invention to provide a failure diagnosis device capable of preventing a misdiagnosis that diagnoses that a transmission has failed.

  In order to solve the above-described problems, the present invention provides a failure diagnosis device for diagnosing whether or not an automatic transmission that transmits engine power to a drive wheel of a vehicle has failed, wherein the automatic transmission includes a required shift speed. A shift determination unit that determines whether or not the gear has been changed, and a first predetermined value is added to a failure determination value when the shift determination unit determines that the gear has not been changed to the required shift stage, and the shift determination unit And a failure determination calculation unit that subtracts a second predetermined value from the failure determination value when it is determined that the required shift speed has been changed, and the calculated failure determination value calculated by the failure determination calculation unit Is characterized in that the automatic transmission is diagnosed as malfunctioning on the condition that is equal to or greater than a predetermined failure diagnosis threshold value.

  According to the present invention, when a shift has failed due to some mechanical trouble, a diagnosis is made that the automatic transmission has failed even though the automatic transmission has not failed. Therefore, it is possible to provide a failure diagnosis apparatus that can prevent the occurrence of the failure.

FIG. 1 is a schematic configuration diagram showing a configuration of a vehicle equipped with a failure diagnosis apparatus according to an embodiment of the present invention. FIG. 2 is a flowchart showing a failure diagnosis process of the failure diagnosis apparatus according to the embodiment of the present invention.

Hereinafter, an electronic control unit (ECU: Electronic Control Unit) 6 as a failure diagnosis device for diagnosing a failure of an automatic transmission 4 according to an embodiment mounted on a vehicle 1 will be described with reference to FIG. This will be described with reference to FIG.
First, the configuration will be described.

  As shown in FIG. 1, the vehicle 1 of this embodiment includes a vehicle body 2, an engine 3 mounted on the vehicle body 2, an automatic transmission 4, a selector module 5, and an ECU 6.

  The vehicle 1 further includes a left front drive shaft 7L, a right front drive shaft 7R, a left front wheel 8L and a right front wheel 8R that are drive wheels, a rear differential 11, a left rear drive shaft 12L, and a right rear drive shaft 12R. The left rear wheel 13L and the right rear wheel 13R, which are driven wheels, are configured.

  The power output from the crankshaft 3a of the engine 3 is shifted by the automatic transmission 4, transmitted from the left front drive shaft 7L to the left front wheel 8L, and from the right front drive shaft 7R to the right front wheel 8R.

  The vehicle 1 is a so-called FF vehicle including a front engine front drive, but may be a vehicle having another structure. For example, it may be a so-called FR vehicle including a front engine rear drive, or a four-wheel drive vehicle such as a full-time 4WD.

  The engine 3 is configured by a known internal combustion engine such as a four-cycle gasoline engine or a diesel engine that performs a series of four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke. The engine 3 is composed of a horizontally mounted engine mounted on the vehicle body 2 so that the axis of the crankshaft 3a faces the vehicle width direction of the vehicle 1, but the vehicle body so that the axis of the crankshaft 3a faces the longitudinal direction of the vehicle 1. 2 may be a vertically mounted engine.

  The automatic transmission 4 houses a transmission 21, a clutch 22, a front differential 23, a transmission actuator 24 that operates the transmission 21, a clutch actuator (not shown) that operates the clutch 22, and each of these components. Case 25 is provided.

  This automatic transmission 4 has a structure of a manual transmission (MT), and an operation performed by a driver in the manual transmission is automated by a shift actuator 24 and a clutch actuator (not shown), thereby automatically shifting. The automatic transmission (AMT: Automatic Manual Transmission) that enables the same speed change as the automatic transmission (AT: Automatic Transmission). The automatic transmission 4 has a manual mode in which the gear position is changed by the operation of the driver, and an automatic mode in which the gear position is automatically changed by the control of the ECU 6. When the automatic transmission 4 is in the automatic mode, the transmission is controlled by the transmission actuator 24 and the clutch actuator connected to the ECU 6.

  The transmission 21 includes a transmission mechanism 31, an input shaft 32, and an output shaft 33, and these components are supported by the case 25.

  Since the speed change mechanism 31 establishes a plurality of shift speeds, for example, a plurality of constant meshing gear pairs (not shown) and any one of the plurality of gear pairs and the input shaft 32 or the output shaft 33 are not shown. And a synchronizer. The speed change mechanism 31 configured in this manner shifts the rotation output from the engine 3 at a speed ratio corresponding to one of the plurality of speed stages. The plurality of gear pairs are provided on an input shaft 32, an output shaft 33, and a shaft such as an intermediate shaft (not shown) arranged in parallel with the input shaft 32 and the output shaft 33.

  Here, as the shift speeds that can be established by the speed change mechanism 31, there are, for example, a shift speed for traveling from the first speed to the fifth speed, and a reverse speed. The number of gears for traveling varies depending on the specifications of the vehicle 1 and is not limited to the first to fifth gears described above. Further, when neither the above-described traveling shift stage or reverse stage is formed in the transmission mechanism 31, for example, when the shift lever is operated to the N range, a neutral stage is formed.

  When the automatic transmission 4 is in the manual mode, the speed change mechanism 31 is changed at the request of the driver, and when it is in the automatic mode, the speed change is changed at the request of the ECU 6. Hereinafter, both the shift stage requested by the driver and the shift stage requested by the ECU 6 are referred to as a requested shift stage. This required shift speed means the required shift speed in the present invention.

The speed change mechanism 31 is connected to the speed change actuator 24 of the automatic transmission 4 and is operated by the speed change actuator 24 to establish a speed selected from a plurality of speeds.
The speed change actuator 24 is composed of an actuator that performs a shift operation such as an electromagnetic or hydraulic shift actuator (not shown) and a select actuator.

  The input shaft 32 is connected to the clutch 22 and the speed change mechanism 31, and transmits the rotation output from the clutch 22 to the speed change mechanism 31. The output shaft 33 is connected to the transmission mechanism 31 and the front differential 23 through a transmission gear provided on the output shaft 33, and transmits the power output from the transmission mechanism 31 to the front differential 23.

  The clutch 22 includes a clutch mechanism 35 that can be switched between a transmission state in which power output from the engine 3 is transmitted to the transmission mechanism 31 and a non-transmission state in which power is not transmitted to the transmission mechanism 31, an input shaft 36, and an output shaft 37. These components are supported by the case 25, respectively.

  The clutch mechanism 35 includes a so-called single plate clutch having an engine side clutch plate 35a such as a flywheel and an AMT side clutch plate 35b. The clutch mechanism 35 is configured by a friction clutch that frictionally engages the engine-side clutch plate 35a and the AMT-side clutch plate 35b to generate a frictional force so as to transmit power. Switching between the transmission state and the non-transmission state in the clutch mechanism 35 is performed by, for example, an electromagnetic or hydraulic clutch actuator.

  The input shaft 36 is connected to the crankshaft 3 a and the clutch mechanism 35, and transmits power output from the crankshaft 3 a to the speed change mechanism 31. The output shaft 37 is connected to the clutch mechanism 35 and the speed change mechanism 31, and transmits the power output from the clutch mechanism 35 to the speed change mechanism 31.

In addition, you may comprise the clutch 22 with the clutch of structures other than a single plate clutch. For example, a so-called multi-plate clutch in which a plurality of discs are alternately stacked may be used.
In addition, the clutch and the various transmission gears are divided into two systems of odd-numbered stages and even-numbered stages, and the so-called dual clutch transmission (DCT: DCT: Dual Clutch Transmission) may be used. In this DCT, a gear shift is performed in a relatively short time by sequentially switching two gear shift systems alternately by a clutch.

  The front differential 23 is connected to a ring gear (not shown) that meshes with a transmission gear provided on the output shaft 33, a left side gear connected to the end of the left front drive shaft 7L, and an end of the right front drive shaft 7R. It has a right side gear and a pinion gear that meshes with both the left side gear and the right side gear.

  The front differential 23 transmits the power input from the ring gear to the left front drive shaft 7L and the right front drive shaft 7R via the pinion gear, the left side gear, and the right side gear, respectively. By the front differential 23, the power of the engine 3 is finally decelerated, and the differential between the left front wheel 8L and the right front wheel 8R connected to the left front drive shaft 7L and the right front drive shaft 7R, respectively, is allowed.

  The selector module 5 is provided in the vicinity of the driver's seat of the vehicle 1 and includes a select lever (not shown) that selects a gear position of the automatic transmission 4. The selector module 5 is mechanically connected to the automatic transmission 4 by a hydraulic unit and a cable (not shown), and is selected from the first to fifth gears selected by the driver, the reverse gear and the neutral gear. Is transmitted to the automatic transmission 4.

  In addition, the selector module 5 is electrically connected to the ECU 6, and selection information such as the gear position selected by the driver is output to the ECU 6, and the shift control of the automatic transmission 4 is executed by the ECU 6.

  The ECU 6 includes a microcomputer having a CPU (Central Processing Unit), a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an input port, an output port, and a network module. ing. The ECU 6 executes arithmetic processing based on data and programs stored in the ROM. An automatic transmission 4 and a selector module 5 are connected to the output port, and a control signal from the ECU 6 is output.

  Further, an output shaft rotation sensor 41 and a wheel speed sensor 42 as a rotation detection unit are connected to the input port of the ECU 6, and detection information is transmitted to the CPU via the input port.

  The output shaft rotation sensor 41 is provided in the vicinity of the right front drive shaft 7R that transmits the power output from the automatic transmission 4 to the right front wheel 8R, and includes a device that detects the rotation speed of the right front drive shaft 7R. It is configured with a non-contact rotation speed sensor that detects irregularities such as gears using a magnetic change and outputs a pulse signal.

  The output shaft rotation sensor 41 may be a non-contact rotation speed sensor that is provided near the output shaft 33 of the speed change mechanism 31 and detects the rotation speed of the output shaft 33. The right front drive shaft 7R of the present embodiment constitutes an output shaft in the present invention.

  As shown in FIG. 1, the wheel speed sensor 42 detects the rotational speed (rpm) of the right front wheel 8R. The wheel speed sensor 42 is constituted by a device that outputs a pulse wave by converting a change in magnetic flux into a change in electric resistance by a non-contact MR element, for example, by rotating a magnet having multiple poles as the right front wheel 8R rotates. The

  The wheel speed sensor 42 is provided on the right front wheel 8R in the present embodiment shown in FIG. 1, but may be another wheel or may be provided on a plurality of wheels. Further, instead of the wheel speed sensor 42, a vehicle speed sensor that detects the vehicle speed (km / h) from the rotational speed (rpm) of the crankshaft 3a of the engine 3 or the rotational speed (rpm) of a drive shaft such as the left front drive shaft 7L. It may be.

  The ECU 6 includes an automatic transmission controller 51, a shift determination unit 52, a failure determination calculation unit 53, and a failure diagnosis unit 54. The ECU 6 performs the functions of the automatic transmission controller 51, the shift determination unit 52, the failure determination calculation unit 53, and the failure diagnosis unit 54. These units may be connected by network (CAN: Controller Area Network) communication. The shift determination unit 52, the failure determination calculation unit 53, and the failure diagnosis unit 54 of the embodiment constitute a failure diagnosis device of the present invention that diagnoses whether or not the automatic transmission has failed.

  The automatic transmission controller 51 controls the transmission actuator 24 and the clutch actuator on the basis of the selection information such as the shift speed output from the selector module 5 and the shift time set in advance so as to match the traveling state of the vehicle 1. The shift in the automatic transmission 4 is controlled. The control signal of the automatic transmission controller 51 is output to the transmission actuator 24 of the automatic transmission 4 and the clutch actuator of the clutch 22, respectively.

  Here, the shift time means the time spent from the start of the shift to the completion when the shift is executed by the automatic transmission controller 51. Specifically, the shift time is the change in the gear ratio in the automatic transmission 4 after the clutch 22 is switched to the non-transmission state by the start of the shift, that is, after the clutch 22 is disconnected. It means the time until the transmission operation is switched to the transmission state again, that is, the speed change operation in which the clutch 22 is frictionally engaged again is completed.

  The shift determination unit 52 determines whether or not the shift stage of the automatic transmission 4 has been changed to the requested shift stage. The shift determination unit 52 may be configured to be able to determine the corresponding shift stage. For example, the shift determination unit 52 is output from a known position sensor provided in each of the traveling shift stage from the first speed stage to the fifth speed stage and the reverse speed stage. The corresponding gear position is determined based on the position information. The position sensors provided at the respective shift stages and the reverse stages are, for example, of the magnetic sensor type, detect the position of the shift fork at each shift stage, and output a detection signal to the shift determination unit 52. The shift determination unit 52 determines the position of the shift fork at each shift stage based on the detection signal of the position sensor, and determines whether or not the shift fork has been changed to each shift stage.

The failure determination calculation unit 53 calculates based on the detection information output from the output shaft rotation sensor 41 or the wheel speed sensor 42 and the determination result determined by the shift determination unit 52 to obtain the calculated failure determination value Kx. When it is determined that the gear position has been changed to the required gear position by the gear shift determination section 52, the failure determination calculation unit 53 determines a second predetermined value with respect to the failure determination value Kc for the corresponding gear position. subtracting the K _2. That is, operation failure determination value Kx is a Kx = _{Kc-K 2.}

  The failure determination value Kc is configured by a value determined in advance for each of a plurality of shift speeds including the first gear to the fifth gear that the automatic transmission 4 has and the reverse gear. A map indicating the relationship between each gear position and the failure determination value Kc is stored in the ROM of the ECU 6 and is referred to when the failure determination calculation unit 53 calculates. Note that when the failure determination calculation unit 53 calculates, the failure determination value Kc may be set to the same value at a plurality of shift stages.

The failure determination calculation unit 53 is a case where it is determined by the shift determination unit 52 that the corresponding shift stage has not been changed to the required shift stage, and after the first determination, the shift operation is executed again, When it is determined by the shift determination unit 52 that the gear position has not been changed to the required shift stage, the output shaft rotation sensor 41 outputs the output shaft after the first determination by the shift determination unit 52 until the time of calculation. of if the right front drive shaft 7R has detected that the rotating, relative to the failure determination value Kc of the corresponding shift stage, adding a first predetermined value K _1. That is, operation failure determination value Kx is a Kx = Kc + _{K 1.}

  The failure determination calculation unit 53 is a case where it is determined by the shift determination unit 52 that the corresponding shift stage has not been changed to the required shift stage, and after the first determination, the shift operation is executed again, When it is determined by the shift determination unit 52 that the gear position has not been changed to the required shift stage, the output shaft rotation sensor 41 performs the right front drive during the period from the determination by the first shift determination unit 52 to the calculation. When it is detected that the shaft 7R is not rotating, the addition and subtraction operations are not performed on the failure determination value Kc for the corresponding gear. That is, the failure determination value Kc for the corresponding gear stage is maintained. In this case, the failure determination value Kc for the corresponding gear stage is set to the operation failure determination value Kx. That is, the arithmetic failure determination value Kx is Kx = Kc.

  The failure diagnosis unit 54 determines whether or not the calculated failure determination value Kx calculated by the failure determination calculation unit 53 is greater than or equal to a predetermined failure diagnosis threshold value S for the corresponding gear. That is, the failure diagnosis unit 54 determines whether or not Kx ≧ S. The failure diagnosis unit 54 diagnoses that the automatic transmission 4 is broken when Kx ≧ S is satisfied.

  The failure diagnosis threshold value S is determined in advance for each of a plurality of shift speeds including the shift speed for traveling from the first speed to the fifth speed that the automatic transmission 4 has, and the reverse speed, similarly to the failure determination value Kc. For example, a map indicating the relationship between each gear position and the failure diagnosis threshold value S is stored in the ROM of the ECU 6 and is referred to when the failure diagnosis unit 54 makes a diagnosis. Note that when the failure diagnosis unit 54 makes a diagnosis, the failure diagnosis threshold value S may be set to the same value at a plurality of shift stages.

  When diagnosing that the automatic transmission 4 has failed, the failure diagnosis unit 54 may notify the automatic transmission controller 51 that the automatic transmission 4 has failed. You may notify a display unit. By these notifications, the automatic transmission controller 51 can stop the shift control of the automatic transmission 4 or inform the driver that the automatic transmission 4 is out of order.

Setting the appropriate gear stage of the failure determination value Kc, the first predetermined value K ₁ or the second predetermined value K _2, and fault diagnosis threshold S varies depending on the model and engine specifications, based on the experience and data And is appropriately selected.

  Next, failure diagnosis processing in the ECU 6 of this embodiment will be described with reference to FIG. The failure diagnosis process described below is repeatedly executed at predetermined time intervals when the ECU 6 detects that an ignition switch (not shown) is turned on.

  First, when information indicating the required shift speed from the driver is transmitted from the selector module 5, the ECU 6 executes shift control of the automatic transmission 4 by the automatic transmission controller 51 and performs the shift operation of the automatic transmission 4. Perform (step S1).

  Next, the ECU 6 determines whether or not the shift stage of the automatic transmission 4 has been changed to the required shift stage by the shift determination unit 52 (step S2).

  If the ECU 6 determines in step S2 that the gear position of the automatic transmission 4 has not been changed to the required gear position, the automatic transmission controller 51 again executes the shift control of the automatic transmission 4, that is, A shift retry is executed, and the shift operation of the automatic transmission 4 is performed again (step S3).

  Subsequently, the ECU 6 again determines whether or not the shift stage of the automatic transmission 4 has been changed to the required shift stage by the shift determination unit 52 (step S4).

If the ECU 6 determines in step S4 that the gear position of the automatic transmission 4 has not been changed to the required gear position, the ECU 6 determines that the shift of the automatic transmission 4 has failed, and from the first determination, It is determined whether or not the right front drive shaft 7R is rotating (step S5).
Specifically, the ECU 6 determines whether or not the shift determination unit 52 determines whether or not the shift stage of the automatic transmission 4 has been changed to the required shift stage in step S2, that is, 1 of the shift determination unit 52 in step S2. It is determined whether or not the right front drive shaft 7R is rotating between the time when the determination is made and the time when the calculation is performed by the failure determination calculation unit 53. Whether or not the right front drive shaft 7R is rotating is determined based on the detection information output from the output shaft rotation sensor 41.

When the ECU 6 determines in step S5 that the right front drive shaft 7R is rotating, the failure determination calculation unit 53 causes the failure determination value Kc of the corresponding shift stage among the plurality of shift stages to be the first. of adding a predetermined value _{K 1} (step S6), and obtains the operation failure determination value Kx. That is, operation failure determination value Kx is a Kx = Kc + _{K 1.}

  Next, the ECU 6 compares the operation failure determination value Kx obtained in step S5 with a failure diagnosis threshold value S of a corresponding gear stage that is predetermined among a plurality of shift stages (step S8), and the operation failure determination value Kx is determined. If it is greater than or equal to the failure diagnosis threshold S, that is, if Kx ≧ S, it is diagnosed that the automatic transmission 4 has failed (step S9), and the failure diagnosis process is terminated.

On the other hand, when the ECU 6 determines in steps S2 and S4 that the gear position of the automatic transmission 4 has been changed to the required gear position, the ECU 6 determines the second determination result for the corresponding gear position failure determination value Kc. by subtracting a predetermined value _{K 2,} obtains the operation failure determination value Kx (step S7). That is, operation failure determination value Kx is a Kx = _{Kc-K 2.} And ECU6 advances a process to step S8.

  Further, when the ECU 6 determines in step S5 that the right front drive shaft 7R is not rotating, the ECU 6 does not perform addition and subtraction operations on the failure determination value Kc of the corresponding shift stage, and does not perform the calculation of the corresponding shift stage. Failure determination value Kc is maintained, and the process proceeds to step S8. In this case, in step S8, the ECU 6 compares the failure determination value Kc of the corresponding gear stage with Kx and the failure diagnosis threshold value S of the corresponding gear stage.

  In step S8, the ECU 6 ends the failure diagnosis process when the calculated failure determination value Kx is not equal to or greater than the failure diagnosis threshold S, that is, when Kx ≧ S is not satisfied.

  Since the ECU 6 as the failure diagnosis apparatus according to the present embodiment is configured as described above, the following effects can be obtained.

That is, the ECU 6 of this embodiment includes a shift determination unit 52 that determines whether or not the automatic transmission 4 has been changed to the required shift stage after the start of the shift, a failure determination calculation unit 53, and a failure diagnosis unit 54. doing. Failure determination calculation section 53, if the automatic transmission 4 by the speed change decision unit 52 is determined not to be changed to the requested shift speed, the first predetermined value K ₁ to the fault judgment value Kc of the appropriate gear stage adding to, subtracting the speed change decision unit 52 the automatic transmission 4 is required gear if stage is determined to be changed to the appropriate speed prescribed value K ₂ from the failure determination value Kc of the second stage by.

  The failure diagnosis unit 54 of the ECU 6 according to the present embodiment causes the automatic transmission 4 to malfunction on condition that the calculated failure determination value Kx calculated by the failure determination calculation unit 53 is equal to or greater than a predetermined failure diagnosis threshold S. Configured to diagnose.

  As a result, the ECU 6 according to the present embodiment determines that the automatic transmission 4 has failed even though the automatic transmission 4 has not failed when the shift has failed due to some mechanical trouble. A misdiagnosis that makes a diagnosis can be prevented.

ECU6 of this embodiment, if it is not changed automatic transmission 4 is the required speed, as described above, first by adding a predetermined value K ₁ to the fault judgment value Kc, the required speed in the opposite If it has, second subtracting a predetermined value K ₂ from the failure determination value Kc, it compares the fault diagnosis threshold S and the arithmetic failure determination value Kx. As a result, a shift failure due to some mechanical trouble can be distinguished from a failure of the automatic transmission 4, so that erroneous diagnosis can be reliably prevented.

  The ECU 6 of this embodiment has an output shaft rotation sensor 41 that detects the rotation of the output shaft 33 of the automatic transmission 4, and the failure determination calculation unit 53 is changed to the required shift stage by the shift determination unit 52. And the condition that the rotation of the right front drive shaft 7R is not detected by the output shaft rotation sensor 41 between the time when the determination is made and the time when the calculation is performed by the failure determination calculation unit 53. As described above, the calculation is not performed on the failure determination value Kc. As long as the right front drive shaft 7R as the output shaft does not rotate, in the case of a mechanical trouble, for example, a trouble due to a poor gear meshing, the trouble is not solved.

  As a result, the ECU 6 according to the present embodiment allows the failure determination value to be used regardless of how many times the gear shift fails if there is a possibility that the gear shift has failed due to a mechanical trouble without rotation of the right front drive shaft 7R. Since Kc is not added, it is possible to prevent a false diagnosis that diagnoses that the automatic transmission 4 has failed even though the automatic transmission 4 has not failed.

The ECU 6 according to the present embodiment makes a determination for each required shift stage among the plurality of shift stages of the automatic transmission 4 by the shift determination unit 52, and the failure determination calculation unit 53 sets the required shift stage by the shift determination unit 52. If it is determined not to be changed, determines a first adding a predetermined value K ₁ to the fault judgment value Kc predetermined for each gear position is changed to the required speed by the speed change decision unit 52 If it is configured to subtract the second predetermined value K ₂ from a predetermined failure determination value Kc for each gear position.

  As a result, the ECU 6 of the present embodiment sets the failure determination value Kc to a value determined in advance for each shift stage, so that a shift failure due to some mechanical trouble is distinguished from a failure of the automatic transmission 4. Therefore, it is possible to reliably prevent misdiagnosis.

  In the present embodiment, the automatic transmission 4 has a structure of a manual transmission (MT: Manual Transmission), and an automatic transmission (AMT: Automated Manual Transmission) having a clutch 22 and a clutch actuator (not shown) as a power transmission mechanism. ) Was described. However, the automatic transmission of the present invention may be configured with other structures. For example, instead of the clutch 22 as a power transmission mechanism and a clutch actuator (not shown), a structure including a torque converter as a fluid transmission mechanism may be used.

  While embodiments of the invention have been disclosed, it will be apparent to those skilled in the art that changes may be made without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims.

1 Vehicle 3 Engine 4 Automatic Transmission 5 Selector Module 6 ECU (Failure Diagnosis Device)
7R Right front drive shaft (output shaft)
DESCRIPTION OF SYMBOLS 11 Rear differential 21 Transmission 22 Clutch 23 Front differential 24 Transmission actuator 31 Transmission mechanism 32, 36 Input shaft 33, 37 Output shaft 35 Clutch mechanism 41 Output shaft rotation sensor (rotation detection part)
42 Wheel speed sensor 51 Automatic transmission controller 52 Shift determination unit (fault diagnosis device)
53 Failure determination calculation unit (failure diagnosis device)
54 Fault diagnosis unit (Failure diagnosis device)
K ₁ First predetermined value K ₂ Second predetermined value Kc Failure determination value (failure determination value) of the corresponding gear stage
Kx Operation failure judgment value S Failure diagnosis threshold value of the corresponding gear (failure diagnosis threshold value)

Claims (3)

A failure diagnosis device for diagnosing whether or not an automatic transmission that transmits engine power to a drive wheel of a vehicle has failed,
A shift determining unit that determines whether or not the automatic transmission has been changed to a required shift stage after the start of a shift;
A first predetermined value is added to the failure determination value when it is determined by the shift determination unit that it has not been changed to the required shift stage, and a determination is made that the shift determination unit has changed to the required shift stage Is a failure determination calculation unit that subtracts the second predetermined value from the failure determination value;
A failure diagnosis unit for diagnosing that the automatic transmission has failed, provided that the calculated failure determination value calculated by the failure determination calculation unit is equal to or greater than a predetermined failure diagnosis threshold value. Characteristic failure diagnosis device. A rotation detector that detects rotation of the output shaft of the automatic transmission;
The failure determination calculation unit is determined that the shift determination unit has not changed to the requested shift speed, and from the time when the determination is made until the time when the failure determination calculation unit calculates. The failure diagnosis apparatus according to claim 1, wherein the failure determination value is not calculated on condition that rotation of the output shaft is not detected by the rotation detection unit. The shift determination unit performs the determination for each requested shift stage among a plurality of shift stages of the automatic transmission,
When it is determined that the shift determination unit has not changed to the required shift stage, the failure determination calculation unit adds a first predetermined value to a predetermined failure determination value for each shift stage, and The second predetermined value is subtracted from a failure determination value predetermined for each of the shift speeds when it is determined by the shift determination section that the gear has been changed to the required shift speed. 2. The failure diagnosis apparatus according to 2.

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