WO2003072980A1

WO2003072980A1 - Power transmission device

Info

Publication number: WO2003072980A1
Application number: PCT/JP2003/001443
Authority: WO
Inventors: Takumi Shinojima; Yasuhiro Nohara
Original assignee: Isuzu Motors Limited; Transtron,Inc.
Priority date: 2002-02-13
Filing date: 2003-02-12
Publication date: 2003-09-04
Also published as: JPWO2003072980A1; AU2003211189A1

Abstract

A power transmission device, comprising a lockup clutch (7) for disengaging and engaging a fluid coupling (2), an automatic transmission clutch (3) installed between the fluid coupling (2) and a transmission (T/M), a control device (22) for controlling the disengagement and engagement of the lockup clutch (7) and the automatic transmission clutch (3), and a trouble detection means (70) for detecting that the lockup clutch (7) causes such a trouble that the clutch is seized in engaged state, wherein the control device (22) disengages the automatic transmission clutch (3) when a vehicle stops after the trouble is detected by the trouble detection means (70), whereby an engine stall when the vehicle stops can be prevented.

Description

Specification

Power transmission technology

The present invention relates to a lock-up clutch for connecting and disconnecting a fluid coupling, an automatic transmission clutch interposed between the fluid coupling and the transmission, a control device for controlling connection and disconnection of the lock-up clutch and the automatic speed change clutch. In particular, a power transmission device improved to enable the vehicle to stop and start without engine stall when a malfunction occurs in which the hook-up clutch is stuck in the connected state. It is about. Background technology

The present inventors have disclosed in Japanese Patent Application Laid-Open No. 2002-2955673 a lock-up clutch for mechanically connecting and disconnecting a fluid coupling connected to an output shaft of an engine, a fluid coupling and a manual transmission. And a control device for controlling the connection and disconnection of the lock-up clutch and the automatic transmission clutch.

This power transmission device is mainly used for vehicles. When the vehicle starts moving, the lock-up clutch is disengaged, an automatic shifting clutch is connected, and the vehicle starts moving by the cleave force of the fluid coupling. When the condition is established, connect the lock-up clutch to integrate the fluid coupling, and drive without slip. Then, when the driver performs the speed change operation, the control device automatically connects and disconnects the automatic transmission clutch.

When the vehicle stops, the control device automatically disconnects the lock-up clutch. As a result, slippage occurs in the fluid coupling, so that the engine is not stalled even if the vehicle is stopped in a state where the gear is engaged in one of the gears and the automatic transmission clutch is connected.

However, in such a power transmission device, the lock-up clutch is connected due to, for example, a short circuit of the electric circuit that operates the lock-up clutch. If the driver tries to stop with the gear engaged in one of the gears, the engine is connected to the wheels (the fluid coupling does not slip) And the engine will stall.

Also, if the vehicle temporarily stops in a state where the lock-up clutch is stuck in the connected state and fails, the vehicle cannot restart using the cleave force of the fluid coupling. There was also a problem that even if the vehicle was moved to a nearby place, it required a large amount of work such as towing. Disclosure of the invention

An object of the present invention is to solve the above problems and provide a power transmission device that can stop a vehicle without engine stall when a failure occurs in which a lock-up clutch is stuck in a connected state. .

The present invention relates to a mouth-up clutch for mechanically connecting and disconnecting a fluid coupling connected to an output shaft of an engine; an automatic transmission clutch interposed between the fluid coupling and a transmission; And a control device for controlling connection and disconnection of the automatic transmission clutch. A power transmission device for disconnecting the mouth-up clutch by the control device when the vehicle stops, wherein the vehicle is in a state where the mouth-up clutch is connected. The control device is provided with a failure detecting means for detecting occurrence of a fixed failure, wherein the automatic transmission clutch is disengaged when the failure detecting means detects a failure during traveling of the vehicle, and thereafter, when the vehicle stops. It is something to do.

The control device disconnects the automatic transmission clutch when a predetermined disconnection condition is satisfied after the failure is detected by the failure detection means, and the disconnection condition is that the brake pedal is depressed, and This may be established when the vehicle speed falls below a predetermined vehicle speed.

The control device may engage the automatic transmission clutch when a predetermined engagement condition is satisfied after the automatic transmission clutch is disconnected.

The contact condition is that a gear of the transmission is geared to one of gears, Further, it may be established when the accelerator opening is equal to or more than a predetermined degree.

The failure detecting means may comprise a short-circuit detecting circuit for detecting a short-circuit in an electric circuit for operating the lock-up clutch.

Other objects, configurations and operational effects of the present invention will become apparent to those skilled in the art after reading and understanding the following detailed description of the embodiments. BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a skeleton diagram of a power transmission device according to one embodiment of the present invention. FIG. 2 is a side sectional view of a power transmission device according to one embodiment of the present invention.

FIG. 3 is a schematic diagram of the hydraulic circuit of FIG.

FIG. 4 is a schematic diagram showing an electric circuit for operating the lock-up clutch and a failure detecting means. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

First, a schematic configuration of a power transmission device according to the present embodiment will be described with reference to FIG. As shown in the figure, a manual transmission T 7M is connected to the engine E via a clutch mechanism 1. The clutch mechanism 1 includes a fluid coupling (fluid coupling) 2 and an automatic speed change clutch 3. In the present embodiment, the automatic transmission clutch 3 is a wet multi-plate clutch. The fluid coupling 2 is provided on the upstream side of a power transmission path from the engine E to the manual transmission T / M, and the automatic transmission clutch 3 is provided in series on the downstream side. Note that the term “fluid coupling” as used herein is a broad concept including a torque converter, and the present embodiment also uses a torque converter.

The fluid coupling 2 includes a pump unit 4 that rotates integrally with a casing 18 connected to the output shaft (crankshaft) la of the engine E, and an input side of the clutch 3 that faces the pump unit 4 in the casing 18. And a stay unit 6 interposed between the turbine unit 5 and the pump unit 4. The fluid coupling 2 is provided with a lock-up clutch 7 for mechanically connecting and disconnecting the pump section 4 and the evening bottle section 5. You. The lock-up clutch 7 is operated by pressure oil from the hydraulic circuit 19.

The input side of the automatic transmission clutch 3 is connected to the evening bin portion 5 of the fluid coupling 2 via the input shaft 3a, and the output side is connected to the input shaft 8 of the manual transmission T / M. The automatic speed change clutch 3 disconnects and connects the power transmission path between the fluid coupling 2 and the manual transmission T / M, and is normally urged in the disconnect direction by a spring (not shown). The automatic transmission clutch 3 is engaged by pressure oil from the hydraulic circuit 19.

The manual transmission T / M has an input shaft 8, an output shaft 9 arranged coaxially with the input shaft 8, and a sub shaft 10 arranged parallel to these. The input shaft 8 is provided with an input main gear 11. On the output shaft 9, a first-speed main gear Ml, a second-speed main gear M2, a third-speed main gear M3, a fourth-speed main gear M4, and a reverse main gear MR are supported, respectively. The 6th speed main gear M6 is fixed. The countershaft 10 has an input sub-gear 12 coupled with the input main gear 11, a first-speed sub-gear C 1 coupled with the first-speed main gear M 1, and a second gear coupled with the second-speed main gear M 2. 3rd speed auxiliary gear C3 which is combined with 3rd speed main gear M3, 4th speed auxiliary gear C4 which is combined with 4th speed main gear M4, and idle gear IR which is combined with reverse main gear MR And a reverse auxiliary gear CR that is coupled to the sixth gear, and a 6-speed auxiliary gear C 6 that is coupled to the 6-speed main gear M 6 are supported.

According to this manual transmission T / M, when the sleeve S / R 1 splined with the hub H / R 1 fixed to the output shaft 9 is spliced with the dog DR of the reverse main gear MR. When the output shaft 9 reversely rotates and the sleeve S / R 1 is splined with the dog D 1 of the first speed main gear M 1, the output shaft 9 rotates at the first speed. Then, when the sleeve S / 2 3 splined to the hub H 23 fixed to the output shaft 9 is splined to the dog D 2 of the second speed main gear M 2, the output shaft 9 rotates at a speed equivalent to the second speed. Then, when the sleeve S / 2 3 is splined to the dog D3 of the third-speed main gear M3, the output shaft 9 rotates at a speed equivalent to the third speed.

When the sleeve S / 45 splined to the hub H / 45 fixed to the output shaft 9 is splined to the dog D4 of the 4-speed main gear M4, the output shaft 9 rotates at the 4th speed. When the sleeve S / 45 is splined to the dog D5 of the input main gear 11, the output shaft 9 rotates at the 5th speed equivalent (direct connection). And fixed to counter shaft 10 When the sleeve S 6 spline-coupled to the hub H 6 is spline-coupled to the dog D 6 of the 6-speed auxiliary gear C 6, the output shaft 9 rotates at a speed equivalent to the sixth speed.

Each of the sleeves S is manually operated by a driver via a shift fork, a shift rod (not shown), and a shift lever 21 in the cab.

The shift switch 21 is provided with a knob switch 20. That is, in the present embodiment, the shift lever 21 of the cab is used to detect the start time of the shift operation by the driver or to determine the timing to start the disconnection operation of the clutch 3 with respect to the lever. Are mounted so as to be able to swing slightly in the shift direction, and a knob switch 20 is provided between these levers and the shift knob. At the time of a gear change operation by the driver, the shift knob swings prior to the operation of the lever, and the knob switch 20 becomes ON, and the clutch disengagement operation is started upon this signal. It is detected by the gear position sensor 21 s that the transmission T / M is in neutral or in any gear by operating the shift lever 21, and the detected gear position is input to the control device 22. Is done.

Further, the depression amount of the accelerator pedal 23 (corresponding to the accelerator opening) is detected by the sensor 24, and the detected value is input to the control device 22. Further, the depression amount of the brake pedal 25 is detected by the sensor 26, and the detected value is input to the control device 22.

The input auxiliary gear 12 of the manual transmission T / M is provided with an input shaft rotation sensor 27 for detecting the rotation speed of the input auxiliary gear 12, and the detected value of the input shaft rotation sensor 27 is Input to the control device 22. Control device 22 calculates the rotation speed of input shaft 8 of transmission T / M based on the detection value of sensor 27 and the gear ratio between input main gear 11 and input auxiliary gear 12. Note that the input shaft rotation sensor 27 may be provided on the input main gear 11 to directly detect the rotation speed of the input shaft 8 of the transmission T / M.

On the input side of the automatic transmission clutch 3, there is provided a bin rotation sensor 28 for detecting the rotation speed of the turbine unit 5. The casing 18 connected to the output shaft 1a of the engine E is provided with an engine rotation sensor 29 for detecting the rotation speed of the engine E. The output shaft 9 of the transmission T / M has a vehicle speed sensor 74 for detecting the vehicle speed. Provided. The detection values of these sensors 28, 29, 74 are input to the control device 22.

Next, details of the fluid coupling 2 and the lock-up clutch 7 will be described with reference to FIG. In the figure, a pump 18 is provided on a casing 18 connected to an output shaft (crankshaft) 1a of an engine E. The pump section 4 is provided rotatably with respect to an input shaft 3 a of a wet multi-plate clutch (automatic transmission clutch) 3 by means of a bearing 80. Further, in the casing 18, an evening bin section 5 is provided so as to face the pump section 4. The evening bin 5 is connected to the input shaft 3 a of the clutch 3. In the figure, the station 6 (see Fig. 1) is omitted for convenience of explanation.

A clutch disc 31 is connected to the turbine section 5 via a damper spring 30. The clutch disk 31 is provided on the outer periphery of the turbine hub 32 of the sunset section 5 so as to be relatively rotatable and slidable in the axial direction so as to face the casing 18. The clutch casing 33 is attached to the outer periphery of the surface of the clutch disc 31 facing the casing 18.

The clutch disc 31 forms an outer chamber 34 between the casing 18 and the clutch disc 31, and forms an inner chamber 35 between the evening bin section 5 and the clutch disc 31. You.

An inner passage 36 is formed in the input shaft 3a, and an outer passage 37 is formed in the outer periphery of the input shaft 3a.

When disconnecting the lock-up clutch 7 in the fluid coupling 2, the control device 22 causes the pressurized oil to flow from the inner passage 36 to the outer chamber 34 between the casing 18 and the clutch disc 31. As shown by the arrow 38 in the upper half of the figure from the outer chamber 34, the water flows through the evening bin 5 and the pump 4, and the rotation of the pump 4 is transmitted to the evening bin 5, and a part of the water flows. Flows through the bearing 80 into the outer passage 37. When the lock-up clutch 7 is brought into contact, the flow of the pressurized oil is switched in the reverse manner as described above. That is, the pressurized oil flows from the outer passage 37 through the bearing 80 to the lower half of the figure in the pump section 4 and the turbine section 5 as indicated by the arrow 39, and also to the inner chamber 35. As a result, the clutch disc 31 is pressed against the casing 18 by the pressure oil in the inner chamber 35. Then, the clutch facing 33 comes into frictional contact with the casing 18, and the rotation of the casing 18 is transmitted to the evening bin section 5 via the clutch disc 31 and the damper spring 30. As a result, the pump section 4 and the turbine section 5 are integrally connected.

The wet multi-plate clutch 3 includes a plurality of clutch plates 41 alternately splined on an input side and an output side in a clutch casing 40 filled with oil. The clutch plates 41 are pressed against each other by the clutch pistons 42 or released to connect and disconnect the clutch. Clutch piston

4 2 is always urged to the disconnected side by the clutch spring 4 3. When a hydraulic pressure exceeding the urging force of the clutch spring 43 is applied to the clutch piston 42, the clutch 3 is engaged.

FIG. 3 shows details of a hydraulic circuit 19 for controlling the fluid coupling 2, the lock-up clutch 7, and the automatic transmission clutch 3.

As shown in the figure, the oil in the oil tank 45 is sucked and discharged by the hydraulic pump 0 P via the filter F, and the discharge pressure is adjusted by the relief valve 47, and the hydraulic oil supply line Pressure oil of a predetermined pressure is supplied to 46.

A five-way lock-up valve 49 for switching the pressurized oil to the fluid coupling 2 is connected to the pressurized oil supply line 46 via the line 48. The lock-up five-way valve 49 is connected to a pressure oil return line 50 for returning pressure oil to the oil tank 45. A throttle valve 51, a cooler 52 and an on-off valve 53 are connected to the pressure oil return line 50.

The on-off valve 53 is normally closed, and opens when pressure oil is supplied from a pilot line 54 connected to the pressure oil supply line 46.

The lock-up five-way valve 49 is switched and controlled by a pilot-control three-way solenoid valve 56 connected to a pilot line 55 of the hydraulic oil supply line 46. Normally, the pilot control three-way solenoid valve 56 is closed, and pressure oil from line 48

From 5, the water flows through the inner passage 36 described in Fig. 2 to the outer chamber 34, then flows into the bin 5 and the pump 4, and then locks through the outer passage 3 7 through the line 58. The oil is returned to the pressurized oil return line 50 via the five-way valve 49 for up. Therefore, locker The clutch is disconnected.

When the three-way solenoid valve 56 for pilot control is opened, the pressure oil from the pilot line 55 switches the five-way valve 49 for mouth up, and the pressure oil from the line 48 changes the line 58 to After passing through the outside passage 37 and passing through the pump section 4 and the turbine section 5, it is confined in the inside chamber 35, and the hydraulic pressure presses the clutch disc 31 against the casing 18. On the other hand, the oil in the outer chamber 34 is pushed out to the line 57 and returned to the oil tank 45 from the oil return line 60 via the lock-up five-way valve 49. Therefore, the lock-up clutch 7 is engaged.

The automatic transmission clutch 3 is connected to a hydraulic oil supply line 46 via a line 68, and the clutch switching three-way valve 61 is connected to the line 68. The operation of the clutch switching three-way valve 61 is controlled by a pilot control three-way solenoid valve 63 connected to a pilot line 62 of the hydraulic oil supply line 46.

In the automatic transmission clutch 3, the clutch switching three-way valve 61 is normally closed. At this time, the automatic transmission clutch 3 is disengaged by the biasing force of the spring 42. When the three-way solenoid valve for pilot control 63 3 is opened, the three-way valve 61 for clutch switching is opened by the pressure oil from the pilot line 62 and the pressure oil is supplied to the automatic transmission clutch 3, and the automatic shifting is performed. Clutch 3 is engaged.

The three-way solenoid valves 56 and 63 for pilot control are opened and closed by an electric signal from the control device 22.

In this power transmission device, the power of the engine E is transmitted in the order of the fluid coupling 2, the automatic transmission clutch 3, and the manual transmission T / M.

The control at the time of starting the vehicle is as follows. When the vehicle is stopped in gear neutral, the driver tries to start and operates the shift lever to the start position. Then, in the shift lever, the shift knob swings prior to the operation of the lever, whereby the knob switch 20 is turned on, and the clutch 3 is disengaged by the signal. Then, by continuously operating the shift lever, the transmission TZM is geared into the starting stage, and when this is detected by the gear position sensor 21s, the clutch 3 is engaged. With this connection, the evening bin 5 is braked from the drive wheel side. Therefore, the pump section 4 slides with respect to the turbine section 5 and a creep force is generated. Therefore, the vehicle starts to move when the brake pedal 25 is released or the accelerator pedal 23 is depressed. This is the same as a normal AT car. After the start, when a predetermined condition (for example, a predetermined vehicle speed or more) is satisfied, the lock-up clutch 7 is brought into contact, and the pump unit 4 and the turbine unit 5 of the fluid coupling 2 rotate integrally. Then, if the driver tries to operate the shift lever 21 of the manual transmission T / M while driving, the shift knob swings prior to the operation of the lever, and the knob switch 20 is turned on. , The automatic transmission clutch 3 is disconnected. Then, the shift lever 21 is operated to shift the manual transmission T / M to one of the gear positions. When this is detected by the gear position sensor 21s, the automatic transmission clutch 3 is engaged. This completes a series of shift operations. Such clutch connection / disconnection control is executed every time a gear shift is performed, thereby realizing a clutch connection / disconnection operation similar to that of a normal MT vehicle. During this shift, the lock-up clutch 7 is kept connected, and the engine power is transmitted to the clutch 3 as it is.

Thereafter, when a predetermined condition (for example, a predetermined vehicle speed or less) that allows the vehicle to stop is established, the lock-up clutch 7 is disconnected. As a result, slippage occurs in the fluid coupling 2, so that the gear of the manual transmission T / M is engaged in one of the gears and the engine is stopped even if the vehicle is stopped with the automatic transmission clutch 3 connected. There will be no stall knocking.

By the way, the present invention provides a power transmission device in which a lock-up clutch is stuck in a connected state (hereinafter, simply referred to as a connection failure) without causing the vehicle to stall. The system can be stopped and restarted. This will be described in detail below.

This power transmission device is provided with a failure detecting means for detecting that the lock-up clutch 7 has failed. As shown in FIG. 4, the failure detection means of the present embodiment includes a short detection circuit 70 that detects a short circuit of the electric circuit 74 that operates the lock-up clutch 7. An electric circuit 74 for operating the lock-up clutch 7 includes a coil 71 for operating a three-way solenoid valve 56 for pilot control shown in FIG. And a FET (field effect transistor) 73 connected to the harness 72. The short detection circuit 70 is connected to the electric circuit 74. . When the mouth-up clutch 7 is actuated to the contact side, the controller 22 turns on the pin 73 to 0 N, the electric circuit Ί4 is energized, and the pilot control three-way solenoid valve 56 is actuated. .

If a short-circuit occurs between the harness 72 and another harness adjacent to it, or inside the FET 73, the control unit 22 does not output the FET 73 ON signal even though the control device 22 does not output the signal. The circuit 74 is energized, the pilot control three-way solenoid valve 56 is operated, and the lock-up clutch 7 is engaged. Then, the lock-up clutch 7 cannot be disengaged and is fixed in the contact state. This is the contact failure of the lock-up clutch 7, and when the contact failure occurs, the pump section 4 and the turbine section 5 of the fluid coupling 2 always rotate integrally. The short-circuit detection circuit 70 detects when the electric circuit 74 is energized even though the control device 22 does not output the ON signal of the FET 73, and the connection failure of the clutch 7 occurs. Is determined.

Then, after the failure detecting means (short detection circuit) 70 detects the contact failure of the lock-up clutch 7, the control device 22 automatically switches to the automatic transmission clutch 3 instead of the lock-up clutch 7 when the vehicle stops. Refuse. This prevents engine stalls. Specifically, after the contact failure is detected by the failure detection means 70, the control device 22 disconnects the automatic transmission clutch 3 when the following disconnection condition is satisfied.

• Disconnection condition

①. Sensor 26 detects depression of brake pedal 25.

②. The operation of the parking brake (not shown) is detected.

③. The operation of HSA (hill start assist brake: not shown) is detected.

④. The rotation speed of the input shaft 8 of the transmission T / M detected by the input shaft rotation sensor 27 is equal to or less than a predetermined rotation speed (ex. 800 rpm).

⑤. The vehicle speed detected by the vehicle speed sensor 74 is lower than the specified vehicle speed (ex. 8 km / h). In each of the above conditions, when (①o r②o r3) and (②o r⑤) are satisfied, the disconnection condition is satisfied, and the control device 22 disconnects the automatic transmission clutch 3. Here, conditions (1) to (3) are conditions for determining the driver's intention to stop. ④ and ⑤ are conditions for judging that the vehicle has decelerated to just before stopping, and have a rotational speed and vehicle speed that do not cause engine stall and knocking even when the engine E and the wheels are connected. Is set. Note that conditions (2), (3), and (4) are backup conditions, and if conditions (1) and (2) are satisfied, it can be determined that the vehicle is about to stop. Therefore, the disconnection condition may be (1) and (d). Further, for the condition (2), instead of detecting the depression of the brake pedal 25, the lighting (ON) of a brake lamp (not shown) may be detected.

Now, it is assumed that a failure of the lock-up clutch 7 has been detected by the failure detection means 70 while the vehicle is running. Then, when the driver depresses the brake pedal 25 in an attempt to stop with the gear of the manual transmission T / M engaged in one of the gears, and the vehicle speed falls below the predetermined vehicle speed, the above-mentioned disconnection condition is satisfied. Automatic transmission clutch 3 is forcibly disconnected regardless of the gear position of the transmission T / M. As a result, the engine E side is separated from the wheel side, so that even after the vehicle actually stops, engine stall and knocking do not occur.

Further, in the present embodiment, in order to enable the vehicle stopped in a state where the lock-up clutch 7 has a connection failure to restart, the control device 22 is automatically activated when the following connection conditions are satisfied. Connect the shifting clutch 3.

• Condition

I. The disconnection condition ((① o r② o r③) a n d (④ o r⑤)) is not satisfied. I I. The depression of the brake pedal 25 is not detected by the sensor 26 (① is not established).

I I I. Parking brake operation is not detected (② is not established).

IV. HSA operation is not detected (③ is not established).

V. The gear position sensor 21 s detects that the transmission T / M has been engaged in any gear (the gear is in the engaged state). VI. The depression amount of the accelerator pedal 23 (accelerator opening) detected by the sensor 24 is equal to or greater than a predetermined value.

VII. The engine speed detected by the engine speed sensor 29 is equal to or higher than a predetermined speed (ex. 850 rpm).

When all the above conditions are satisfied (I and II and III and IV and V and VI and VII), the contact condition is satisfied, and the controller 22 engages the automatic clutch 3. Here, the conditions I to IV are conditions opposite to the above-mentioned disconnection conditions, and are conditions for judging that the driver has no intention to stop. V to VII are conditions for determining the driver's intention to start. Note that the conditions other than V and VI are backup conditions, and in effect, if the conditions of V and VI are satisfied, it can be determined that the driver is willing to start. Therefore, the contact condition may be V and VI.

Now, suppose that the driver depresses the brake pedal 25 and stops the vehicle while the failure detecting means 70 has determined that the connection failure of the lock-up clutch 7 has occurred while the vehicle is running. In this state, the automatic transmission clutch 3 is disconnected because the disconnection condition is satisfied. Thereafter, the driver depresses the accelerator pedal 23 with the gear of the manual transmission T / M for starting the vehicle engaged in one of the gears, and the depression amount (accelerator opening) and the engine speed are set to the predetermined values. Is exceeded, the above-mentioned connection condition is satisfied, and the control device 22 connects the automatic transmission clutch 3. As a result, the power of the engine E is transmitted to the wheel side, and the vehicle starts.

As described above, according to the power transmission device of the present embodiment, even if a failure occurs in which the lock-up clutch 7 is stuck in the connected state, when the vehicle stops thereafter, instead of the lock-up clutch 7, Since the automatic transmission clutch 3 is disengaged, engine stall and knocking do not occur.

In addition, when the vehicle restarts thereafter, the automatic transmission clutch 3 is engaged, so that the vehicle can start even when the lock-up clutch 7 has a connection failure. Therefore, it is possible to move the vehicle to a safe place or to a repair shop without performing major work such as towing.

Although the short detection circuit 70 has been described as the failure detection means, the present invention The means is not limited in point, and any means can be applied as long as it can detect that the lock-up clutch 7 is stuck in the connected state.

This application is based on a patent application No. 2002-35842 (filed on Feb. 13, 2002), the contents of which are incorporated herein by reference. Industrial applicability

The present invention can be widely applied to vehicles equipped with a diesel engine or a gasoline engine.

Claims

The scope of the claims

1. Open-up clutch that connects and disconnects the fluid coupling connected to the output shaft of the engine, an automatic transmission clutch that is interposed between the fluid coupling and the transmission, and disconnection and connection of these lock-up clutch and automatic transmission clutch A power transmission device comprising: a control device for controlling the power transmission device; anda failure detection means for detecting that a failure has occurred in which the hook-up clutch is fixed in a connected state. If the failure detecting means detects that a failure has occurred during running of the vehicle and the above-mentioned lock-up clutch is connected, the automatic transmission clutch is cut off when the vehicle stops. A power transmission device characterized by the above-mentioned.

2. The control device disconnects the automatic transmission clutch when a predetermined disconnection condition is satisfied, after the failure detection means detects that the lock-up clutch is engaged and the lock-up clutch is in a connected state. 2. The power transmission device according to claim 1, wherein the disconnection condition is satisfied when a brake pedal is depressed and the vehicle speed becomes equal to or lower than a predetermined vehicle speed.

3. The power transmission device according to claim 1, wherein the control device engages the automatic transmission clutch when a predetermined engagement condition is satisfied after the automatic transmission clutch is disengaged.

4. The power transmission device according to claim 3, wherein the contact condition is satisfied when the gear of the transmission is geared into any one of the gear stages and the accelerator opening is equal to or greater than a predetermined opening.

5. The power transmission device according to any one of claims 1 to 4, wherein the failure detection means includes a short circuit detecting a short circuit in an electric circuit for operating the lock-up clutch.