Power transmission device for vehicle

Abstract

The present application relates to a power transmission device for a vehicle. In the case where the lock-up clutch is held in a released state at the time of abnormality detection for executing a fail-safe mode, and the N range is set, the friction engagement device is prevented from being engaged due to a failure of one of the hydraulic control valves. In the N range, the on-off solenoid valve (SC1) is connected, the on-off solenoid valve (SC3) is disconnected, and the hydraulic control valves (SLU, SL2) are disconnected. If the hydraulic control valve (SLU) is normal, the lock-up clutch (LU) is held in a released state by stopping the hydraulic output thereof, and the hydraulic supply to the hydraulic control valve (SL2) is cut off, so that the drive clutch (C2) is prevented from being engaged in the case where the hydraulic control valve (SL2) fails. In the case where the hydraulic control valve (SLU) actually fails, the lock-up clutch (LU) is released substantially in the same manner as in the fail-safe mode in which the hydraulic control valve (SLU) is connected, and is brought into a neutral state by the disconnection control of the hydraulic control valve (SL2).

Description

Technical Field

[0001] This invention relates to power transmission devices for vehicles, and more particularly to improvements to power transmission devices for vehicles that are configured to a fail-safe mode capable of forward driving when an abnormality is detected in the hydraulic control valve. Background Technology

[0002] The following vehicle power transmission device is known, which includes: (a) a fluid transmission with a lock-up clutch; and (b) an automatic transmission disposed between an input shaft and an output shaft that transmits power from a drive source via the fluid transmission, and is equipped with a hydraulic forward engagement device and a hydraulic reverse engagement device to enable forward and reverse driving. The device described in Patent Document 1 is one example, which includes a torque converter 16 as a fluid transmission and a vehicle transmission 78 as an automatic transmission. The automatic transmission has a first power transmission path and a second power transmission path arranged in parallel between the input shaft and the output shaft. The first power transmission path is provided with a gear transmission device, a hydraulic gear forward friction engagement device (C1), and a hydraulic gear reverse friction engagement device (B1). A hydraulic synchronous engagement device (D1) is provided in series with the gear forward friction engagement device and the gear reverse friction engagement device, enabling forward and reverse driving. On the other hand, the second power transmission path is provided with a belt continuously variable transmission (60) and a hydraulic belt driving friction engagement device (C2), enabling forward driving.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-124255 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] However, in such vehicle power transmission systems, various hydraulic control valves and switching valves are required to control the hydraulic pressure of the hydraulic engagement device or the switching oil circuit. From the viewpoint of reducing the number of components, it is considered to use a common hydraulic control valve to control multiple hydraulic pressures. However, if the hydraulic control valve is shared in this way, a single hydraulic control valve will be fixed in a hydraulic output state, which is a malfunction. Even in neutral, the engagement device may still engage, causing discomfort to the driver.

[0008] For example, Figure 2This is an example of a hydraulic control circuit for a vehicle power transmission device, which includes a forward clutch C1 as a friction engagement device for gear forward movement, a reverse brake B1 as a friction engagement device for gear reversal, a travel clutch C2 as a friction engagement device for travel, a synchronous engagement clutch S1 as a synchronous engagement device, and a lock-up clutch LU. The hydraulic control circuit 70 includes a first switching valve 110, a second switching valve 112, a third switching valve 114, and a fault switching valve 116 for switching oil circuits, and a lock-up hydraulic control valve SLU, a first hydraulic control valve SL1, and a second hydraulic control valve SL2 for controlling hydraulic pressure.

[0009] The first switching valve 110 can switch between a first connection state (shown by a solid line) and a second connection state (shown by a dashed line) electrically via an ON-OFF solenoid valve SC1. The second switching valve 112 can switch between the first connection state (shown by a solid line) and the second connection state (shown by a dashed line) electrically via an ON-OFF solenoid valve SC2. The control hydraulic pressure Psl1 or pipeline pressure PL supplied from the second switching valve 112 to the first hydraulic control valve SL1 is supplied as the S1 engagement hydraulic pressure Ps1 to the synchronous engagement clutch S1, which engages synchronously based on the S1 engagement hydraulic pressure Ps1. The third switching valve 114 can switch between the first connection state (shown by a solid line) and the second connection state (shown by a dashed line) electrically via an ON-OFF solenoid valve SC3. In the first connected state of the third switching valve 114, the control hydraulic pressure Pslu obtained by adjusting the pipeline pressure PL as the initial pressure through the lock-up hydraulic control valve SLU is used as the control hydraulic pressure for the lock-up engagement hydraulic pressure Plu. On the other hand, in the second connected state of the third switching valve 114, the control hydraulic pressure Pslu obtained by adjusting the R gear pressure PR as the initial pressure through the lock-up hydraulic control valve SLU is supplied to the reversing brake B1 as the B1 engagement hydraulic pressure Pb1. The lock-up hydraulic control valve SLU is used for the hydraulic control of the lock-up clutch LU and the reversing brake B1.

[0010] The fault switching valve 116 can switch between a first connection state (shown by the solid line) and a second connection state (shown by the dashed line). In the first connection state, the control hydraulic pressure Psl1, obtained by adjusting the D gear pressure PD as the initial pressure through the first hydraulic control valve SL1, is supplied to the forward clutch C1 as the C1 engagement hydraulic pressure Pc1. The hydraulic control of the forward clutch C1 and the synchronous engagement clutch S1 uses a common first hydraulic control valve SL1. When the fault pressure Pfail is supplied, the fault switching valve 116 is mechanically switched to the second connection state; when the supply of the fault pressure Pfail is stopped, the fault switching valve 116 is mechanically switched to the first connection state. The second hydraulic control valve SL2 uses the D gear pressure PD or the reverse driving hydraulic pressure Plimp supplied from the fault switching valve 116 as the initial pressure to control the hydraulic pressure. Its control hydraulic pressure Psl2 is supplied to the belt-driven clutch C2 as the C2 engagement hydraulic pressure Pc2. Thus, the belt-driven clutch C2 is engaged and released according to the control hydraulic pressure Psl2, enabling forward driving using a belt-driven continuously variable transmission.

[0011] On the other hand, when a predetermined anomaly is detected in a vehicle power transmission device equipped with such a hydraulic control circuit 70, where there is a possibility of a failure (ON failure) where the lock-up hydraulic control valve SLU is fixed in the hydraulic output state, it is required to be set to a fail-safe mode that allows forward driving. The lock-up hydraulic control valve SLU is used to control both the engagement hydraulic pressure Plu of the lock-up clutch LU and the engagement hydraulic pressure Pb1 of the reverse brake B1. Therefore, when the lock-up hydraulic control valve SLU is fixed in the hydraulic output state, the lock-up clutch LU is always engaged except during reverse driving, thus directly connecting the drive power source to the wheels. When the vehicle stops, the rotation of the drive power source stops, which may cause the engine to stall.

[0012] The fail-safe mode is a mode used to avoid direct connection of such driving force sources and to enable forward driving. For example, by setting the first switching valve 110 to the second connection state, setting the second switching valve 112 to the second connection state, setting the third switching valve 114 to the first connection state, and using the hydraulic output of the lock-up hydraulic control valve SLU, the fail-safe switching valve 116 is switched to the second connection state based on the fail-safe pressure Pfail, thereby enabling the fail-safe mode. Figure 4This is a hydraulic circuit diagram showing the hydraulic transmission path in the fail-safe mode, indicated by thick lines. When the fail-safe switching valve 116 is switched to the second connection state, the fail-safe pressure Pfail is supplied to the lock-up release circuit 132, and the lock-up clutch LU is kept in the released state. In this state, the belt-driven clutch C2 is engaged by the hydraulic control of the second hydraulic control valve SL2, thereby enabling forward movement using the belt-driven continuously variable transmission. In other words, the belt-driven clutch C2 is a forward engagement device that engages it in fail-safe mode to enable forward movement.

[0013] Here, when the neutral (N) gear, which cuts off power transmission, is selected during the fault-safe mode anomaly detection, for example, when the switching solenoid valve SC1 is disconnected (de-energized state) and the first switching valve 110 is in the first connected state, the output of the fault pressure Pfail stops, and no hydraulic pressure is supplied to the lock-up release circuit 132. Therefore, when the lock-up hydraulic control valve SLU fails and is actually fixed in the hydraulic output state, the lock-up clutch LU engages in the neutral gear based on the output hydraulic pressure of the lock-up hydraulic control valve SLU. When the reverse gear (R gear) for reverse driving is selected in this state, the third switching valve 114 is switched to the second connected state, the reverse brake B1 is engaged, and the lock-up clutch LU is released. However, when the reverse brake B1 suddenly engages due to the failure of the lock-up hydraulic control valve SLU, the engine may stall due to the residual pressure of the lock-up clutch LU. In addition, when switching to fail-safe mode by selecting the forward gear (D gear) from neutral, fault pressure Pfail is supplied to the lock-up release oil circuit 132 to release the lock-up clutch LU. However, if the engagement of the driving clutch C2 is too fast, the engine may stall due to the residual pressure of the lock-up clutch LU.

[0014] On the other hand, Figure 4 In the fail-safe mode shown, if the hydraulic output of the second hydraulic control valve SL2 stops and releases the driving clutch C2, the neutral gear can be engaged while the lock-up clutch LU remains in the released state, preventing engine stalling as described above. However, if a failure occurs where the second hydraulic control valve SL2 is locked in the hydraulic output state, the driving clutch C2 will remain engaged even in neutral, potentially causing discomfort to the driver. In particular, even if the lock-up hydraulic control valve SL2 is functioning normally, the engine may still transition to fail-safe mode in cases such as when fuel is depleted. In such situations, due to a malfunction of the second hydraulic control valve SL2, the driving clutch C2 will remain engaged even in neutral, reducing robustness.

[0015] The present invention was made in light of the above situation, and its purpose is to prevent the friction engagement device from engaging when the lock-up clutch is in the released state and the neutral position is established during fault detection in fail-safe mode.

[0016] Methods for solving problems

[0017] To achieve this objective, the vehicle power transmission device of the first invention comprises: (a) a fluid transmission device with a lock-up clutch; and (b) an automatic transmission disposed between an input shaft and an output shaft that transmits power from a driving power source via the fluid transmission device, and equipped with a hydraulic forward engagement device and a hydraulic reverse engagement device to enable forward and reverse driving, characterized in that (c) the vehicle power transmission device has a hydraulic control circuit, the hydraulic control circuit comprising: a first switching valve, a third switching valve, and a fault switching valve for oil circuit switching; and a lock-up hydraulic control valve and a second hydraulic control valve for hydraulic control, (c-1) the first The switching valve can switch between a first connection state and a second connection state. In the first connection state, the initial pressure of various hydraulic systems is output as the D gear pressure for forward driving. In the second connection state, the control hydraulic pressure of the lock-up hydraulic control valve is output as the fault pressure to the fault switching valve. (c-2) The third switching valve can switch between a first connection state and a second connection state. In the first connection state, the control hydraulic pressure of the lock-up hydraulic control valve is output to the lock-up engagement oil circuit that controls the engagement hydraulic pressure of the lock-up clutch. In the second connection state, the control hydraulic pressure of the lock-up hydraulic control valve is output as the fault pressure to the fault switching valve. The control hydraulic pressure of the locking hydraulic control valve is output to the reversing engagement device. (c-3) The fault switching valve can switch between a first connection state and a second connection state. In the first connection state of the fault switching valve, the D-position pressure supplied when the first switching valve is in the first connection state is output to the second hydraulic control valve. In the second connection state of the fault switching valve, the pipeline pressure supplied through a different path than the D-position pressure is output as reversing hydraulic pressure to the second hydraulic control valve, and the fault pressure supplied when the first switching valve is in the second connection state is output to the lock-up release oil circuit for forcibly releasing the lock-up clutch. When the fault switching valve is supplied with the fault pressure, it is mechanically switched to the second connection state; when the fault pressure supply is stopped, the fault switching valve is mechanically switched to the first connection state. (c-4) The second hydraulic control valve is disposed between the fault switching valve and the forward engagement device. By controlling the D-gear pressure or the reverse driving hydraulic pressure supplied from the fault switching valve and outputting it to the forward engagement device, the forward engagement device is engaged and released. (d) The vehicle power transmission device includes a control device that detects a predetermined abnormality where there is a possibility of failure in which the locking hydraulic control valve is fixed in the hydraulic output state.The fail-safe mode is set as follows: the first switching valve is set to the second connection state, the third switching valve is set to the first connection state, and the fail-safe switching valve is switched to the second connection state based on the fault pressure through the hydraulic output of the lock-up hydraulic control valve. Thus, the fault pressure is supplied to the lock-up release circuit, the lock-up clutch is held in the released state, and the forward engagement device is engaged by the hydraulic control of the second hydraulic control valve to enable forward movement. (e) When the control device selects the neutral gear (disconnecting power transmission) during the fault detection, the first switching valve is set to the second connection state, the third switching valve is set to the first connection state, the hydraulic output of the lock-up hydraulic control valve is stopped, and the hydraulic output of the second hydraulic control valve is also stopped.

[0018] The second invention, in the vehicle power transmission device of the first invention, (a) the automatic transmission has a first power transmission path and a second power transmission path arranged in parallel between the input shaft and the output shaft. The first power transmission path is provided with a gear transmission device, a hydraulic gear forward friction engagement device, and a hydraulic gear reverse friction engagement device. A hydraulic synchronous engagement device is connected in series with the gear forward friction engagement device and the gear reverse friction engagement device, enabling forward and reverse travel. On the other hand, the second power transmission path is provided with a belt-type continuously variable transmission and a hydraulic belt-driving friction engagement device, enabling forward travel. The friction engagement device for driving is the forward engagement device, and the friction engagement device for gear reversing is the reverse engagement device. (b) In addition to the first switching valve, the third switching valve, the fault switching valve, the lock-up hydraulic control valve, and the second hydraulic control valve, the hydraulic control circuit also includes a second switching valve for oil circuit switching and a first hydraulic control valve for hydraulic control. (b-1) In the second connection state of the first switching valve, the pipeline pressure is output to the second switching valve as the R gear pressure for reverse driving. (b-2) In the first connection state of the third switching valve, the D gear pressure supplied when the first switching valve is in the first connection state. Pressure is output to the second switching valve, and the pipeline pressure is output to the lock-up hydraulic control valve. On the other hand, in the second connection state of the third switching valve, when the first switching valve is in the second connection state, the R-position pressure supplied via the second switching valve is output to the lock-up hydraulic control valve. (b-3) The second switching valve can switch between the first connection state and the second connection state. In the first connection state of the second switching valve, the D-position pressure supplied when both the first and third switching valves are in the first connection state is output to the fault switching valve, and the pipeline pressure is output to the first hydraulic control valve. The control hydraulic pressure from the first hydraulic control valve is output to the synchronous engagement device, and the R-position pressure supplied when the first switching valve is in the second connection state is output to the third switching valve. When the second switching valve is in the second connection state, the D-position pressure supplied when the first switching valve is in the first connection state is output to the fault switching valve. When both the first and third switching valves are in the first connection state, the D-position pressure is output to the first hydraulic control valve. The control hydraulic pressure from the first hydraulic control valve is output to the fault switching valve, and the pipeline pressure is output to the synchronous engagement device.(b-4) In the first connection state of the fault switching valve, when the first switching valve is in the first connection state and the second switching valve is in the second connection state, and when the first switching valve is in the first connection state, the third switching valve is in the first connection state and the second switching valve is in the first connection state, the supplied D-gear pressure is output to the second hydraulic control valve. When the first switching valve is in the first connection state, the third switching valve is in the first connection state and the second switching valve is in the second connection state, the control hydraulic pressure supplied to the first hydraulic control valve is output to the gear forward friction engagement device. On the other hand, (c) when the control device selects the reverse gear for reverse driving during the fault detection, it sets the first switching valve to the second connection state, sets the second switching valve to the first connection state, sets the third switching valve to the second connection state, sets the locking hydraulic control valve to the hydraulic output state, and sets the first hydraulic control valve to the hydraulic output state.

[0019] Invention Effects

[0020] In such a vehicle power transmission device, when a specified abnormality is detected, indicating a possibility of failure where the lock-up hydraulic control valve is fixed in the hydraulic output state, the first switching valve is set to the second connection state, and the third switching valve is set to the first connection state. Based on the fault pressure generated by the hydraulic output of the lock-up hydraulic control valve, the fault switching valve is switched to the second connection state. This fault pressure is then supplied to the lock-up release circuit, the lock-up clutch is held in the released state, and hydraulic pressure for reverse travel is supplied to the second hydraulic control valve via the fault switching valve. Therefore, the forward engagement device is engaged by the hydraulic control of the second hydraulic control valve, thus establishing a fail-safe mode for forward travel. This is not only possible when the lock-up hydraulic control valve is functioning normally, but also even if the lock-up hydraulic control valve actually fails. Furthermore, by holding the lock-up clutch in the released state, appropriate reverse travel can be performed without engine stalling when the vehicle stops.

[0021] Furthermore, if neutral is selected during the fault-safe mode anomaly detection, the first switching valve is set to the second connection state, the third switching valve is set to the first connection state, the hydraulic output of the lock-up hydraulic control valve is stopped, and the hydraulic output of the second hydraulic control valve is also stopped. In this case, if the lock-up hydraulic control valve is functioning normally, its hydraulic output is stopped, and the fault pressure supply to the fault switching valve is stopped, switching the fault switching valve to the first connection state. Thus, the lock-up clutch is kept in the released state, preventing engine stalling caused by the drive power source stopping rotation due to lock-up clutch engagement when shifting from neutral to reverse or drive. Furthermore, by setting the first switching valve to the second connection state and the fault switching valve to the first connection state, the hydraulic supply from the fault switching valve to the second hydraulic control valve is cut off. Therefore, even if a failure occurs in which the second hydraulic control valve is fixed in the hydraulic output state, the forward engagement device will not be engaged. This prevents the following situation: due to a fault in the second hydraulic control valve, the forward engagement device is engaged even in neutral gear, causing discomfort to the driver.

[0022] On the other hand, even if the lock-up hydraulic control valve fails, the fault-switching valve is switched to the second engagement state based on the fault pressure generated by the hydraulic output of the lock-up hydraulic control valve, becoming essentially the same as the fail-safe mode, even when in the aforementioned neutral position. That is, by supplying fault pressure from the fault-switching valve to the lock-up release circuit, the lock-up clutch is kept in the released state. When shifting from neutral to reverse or forward, it prevents the drive power source from stopping rotation and causing the engine to stall due to the lock-up clutch engaging. Furthermore, by stopping the hydraulic output of the second hydraulic control valve, the forward engagement device is released, resulting in a neutral state where power transmission is cut off.

[0023] In the second invention, the automatic transmission includes: a first power transmission path equipped with a gear-type transmission device, a gear forward friction engagement device, a gear reverse friction engagement device, and a synchronous engagement device; and a second power transmission path equipped with a belt-type continuously variable transmission and a belt driving friction engagement device. When the hydraulic control circuit includes a second switching valve and a first hydraulic control valve, and reverse gear is selected during fault-tolerant mode anomaly detection, the first switching valve is set to a second connection state, the second switching valve is set to a first connection state, the third switching valve is set to a second connection state, the lock-up hydraulic control valve is set to a hydraulic output state, and the first hydraulic control valve is set to a hydraulic output state. Thus, based on the hydraulic pressure supplied from the third switching valve to the lock-up hydraulic control valve, the gear reverse friction engagement device is engaged, and based on the control hydraulic pressure supplied from the second switching valve to the first hydraulic control valve, the synchronous engagement device is engaged, enabling reverse driving using the gear-type transmission device. In this case, in the neutral gear, the lock-up clutch remains in the released state regardless of whether the lock-up hydraulic control valve actually fails. Therefore, the following effect can be achieved: when shifting from neutral to reverse, it is possible to prevent the drive power source from stopping rotation due to the engagement of the lock-up clutch, thus preventing the engine from stalling. Attached Figure Description

[0024] Figure 1 This is a main structural diagram illustrating the schematic structure of a power transmission device for vehicles, which is an embodiment of the present invention.

[0025] Figure 2 This is an explanation Figure 1 The hydraulic circuit diagram of the main part of the hydraulic control circuit of the power transmission device for vehicles.

[0026] Figure 3 This means that it is possible to use Figure 1 The diagram shows the relationship between the multiple power transmission gears and multiple driving modes that can be switched using the D gear in a vehicle's power transmission device, the working states of multiple solenoid valves, and the engagement and release states of multiple engagement devices.

[0027] Figure 4 It is represented by thick lines Figure 1 Hydraulic circuit diagram showing the hydraulic transmission path when the vehicle's power transmission device is set to the fail-safe mode in D gear.

[0028] Figure 5 It is represented by thick lines Figure 1 Hydraulic circuit diagram showing the hydraulic transmission path when the vehicle's power transmission device is switched to the neutral (N) position.

[0029] Figure 6 It is represented by thick lines Figure 1Hydraulic circuit diagram showing the hydraulic transmission path when the vehicle's power transmission device is switched to R gear.

[0030] Figure 7 It is represented by thick lines. Figure 5 The hydraulic circuit diagram shows the hydraulic transmission path when the hydraulic control valve SLU is locked in the N position and fixed in the hydraulic output state during a failure.

[0031] Explanation of reference numerals in the attached figures

[0032] 10: Vehicle power transmission device; 12: Engine (driving power source); 14: Torque converter (fluid transmission device); 16: Automatic transmission; 22: Input shaft; 24: Belt continuously variable transmission; 28: Gear transmission mechanism (gear transmission device); 30: Output shaft; 70: Hydraulic control circuit; 80: Electronic control device (control device); 110: First switching valve; 112: Second switching valve; 114: Third switching valve; 116: Fault switching valve; LU: Lock-up clutch; TP1: First power transmission path; TP2: Second power transmission path; C1: Forward clutch (gear...) C2: Clutch for forward travel (with friction engagement device for travel and forward engagement device) B1: Reverse brake (gear reverse friction engagement device and reverse engagement device) S1: Synchronous engagement clutch (synchronous engagement device) SLU: Lock-up hydraulic control valve SL1: First hydraulic control valve SL2: Second hydraulic control valve PL: Line pressure Pfail: Fault pressure Plimp: Hydraulic pressure for reverse travel PD: D gear pressure PR: R gear pressure Psl1, Psl2: Control hydraulic pressure Detailed Implementation

[0033] This invention is preferably applied to power transmission devices for vehicles driven by an engine (internal combustion engine) as the driving force source, but it can also be applied to power transmission devices for other vehicles, such as hybrid vehicles, which use both an engine and an electric motor as driving force sources. The first switching valve, second switching valve, and third switching valve are configured, for example, to switch connection states based on the signal pressure of a switching solenoid valve, but they can also be valves such as spool valves whose valve cores move directly via a switching solenoid, or they can use a drive device other than a solenoid, and various methods can be employed to switch connection states. The first and second connection states of each switching valve can be either the first connection state when the solenoid is in an energized state and the second connection state when the solenoid is de-energized, or the second connection state when connected and the first connection state when disconnected. The locking hydraulic control valve, first hydraulic control valve, and second hydraulic control valve are preferably linear solenoid valves, for example, whose output hydraulic pressure changes continuously according to the excitation current, but the hydraulic pressure can also be changed continuously through proportional control or the like. These hydraulic control valves can be controlled by the solenoid valve itself to output a predetermined hydraulic pressure, but the hydraulic pressure can also be controlled via a hydraulic control valve or the like based on the output hydraulic pressure of the solenoid valve. Alternatively, the control hydraulic pressure output from the hydraulic control valve can be directly supplied to the locking device to lock it in place. However, the locking torque of the locking device can also be indirectly controlled based on the control hydraulic pressure from the hydraulic control valve.

[0034] The vehicle power transmission device of the present invention includes, for example, the above-described features. Figure 2 It is constructed using the hydraulic control circuit shown, but Figure 2 The hydraulic control circuit described is just one example; the location or presence of the second switching valve 112 and the first hydraulic control valve SL1 can be appropriately modified. The connection states of the other switching valves 110, 114, and 116 can also be partially modified. The hydraulic circuits related to the locking engagement circuit 130 and the locking release circuit 132 can also be appropriately modified. The synchronous engagement clutch S1, which serves as a synchronous engagement device, can also be omitted. Figure 2 The invention relates to a power transmission device for a vehicle equipped with an automatic transmission, which includes: a first power transmission path having a gear-type transmission device, a gear forward friction engagement device, a gear reverse friction engagement device, and a synchronous engagement device; and a second power transmission path having a belt-type continuously variable transmission and a belt-driven friction engagement device. However, any automatic transmission capable of forward and reverse travel via at least the forward and reverse engagement devices is acceptable. For example, a forward clutch C1, which serves as a gear forward friction engagement device, can engage in a fail-safe mode to enable forward travel. In this case, a belt-type continuously variable transmission and a second power transmission path with a travel friction engagement device are not necessarily required, and various methods can be employed.

[0035] [Example]

[0036] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that in the following embodiments, the drawings are appropriately simplified or modified for illustrative purposes, and the size ratios, shapes, etc. of the parts are not necessarily depicted accurately.

[0037] Figure 1 This is a main structural diagram illustrating the general structure of a vehicle power transmission device 10, which is an embodiment of the present invention. The diagram is shown with multiple parallel axes positioned in a single plane. This vehicle power transmission device 10 is preferably a transverse type used in FF (front-engine, front-wheel drive) vehicles. The output of the engine 12, which serves as the driving force source, is transmitted from the torque converter 14 (a fluid transmission device) via the automatic transmission 16 to the differential gear unit 18 and distributed to the left and right drive wheels 20L and 20R. The engine 12 is an internal combustion engine such as a gasoline engine or a diesel engine. The torque converter 14 includes a pump impeller 14p connected to the crankshaft of the engine 12 and a turbine impeller 14t connected to the input shaft 22 of the automatic transmission 16. Power is transmitted via fluid (working oil) and directly connected via a lock-up clutch LU. A mechanical oil pump 74 is provided on the pump impeller 14p, which outputs hydraulic pressure driven by the rotation of the engine 12, and is used as the hydraulic source for the hydraulic control circuit 70 shown by the dashed line. The connection destination, i.e. the installation location, of the oil pump 74 can be changed appropriately, and an electric oil pump can also be used.

[0038] Figure 2 Specifically, the main part of the hydraulic control circuit 70, namely the hydraulic operation control unit 72 composed of valve bodies, etc., uses a lock-up hydraulic pressure Plu, which is the engagement hydraulic pressure of the lock-up clutch LU of the torque converter 14. This lock-up hydraulic pressure Plu is pressure-controlled by the lock-up hydraulic pressure control valve SLU, and the lock-up clutch LU is engaged and released according to this lock-up hydraulic pressure Plu. The lock-up hydraulic pressure Plu controls, for example, the differential pressure between the lock-up side oil chamber and the lock-up release side oil chamber. The lock-up hydraulic pressure control valve SLU is a linear solenoid valve for hydraulic control. The output hydraulic pressure Pslu is electrically controlled by the electronic control device 80, thereby regulating the lock-up hydraulic pressure Plu. The output hydraulic pressure Pslu also acts as the control hydraulic pressure Pslu. The same applies to other hydraulic control valves.

[0039] The automatic transmission 16 includes: an input shaft 22 integrally disposed with the turbine shaft, which serves as the output rotating component of the torque converter 14; a belt-driven continuously variable transmission (CVT) 24 connected to the input shaft 22; a forward / reverse switching device 26 and a gear transmission mechanism 28, also connected to the input shaft 22 and disposed parallel to the belt-driven CVT 24; an output shaft 30 serving as a shared output rotating component of the belt-driven CVT 24 and the gear transmission mechanism 28; and a reduction gear assembly 32, the small-diameter gear 34 of which meshes with the ring gear 36 of the differential gear assembly 18. In the automatic transmission 16 configured as described above, the output of the engine 12 is transmitted from the torque converter 14 to the output shaft 30 via the belt-driven CVT 24, or via the forward / reverse switching device 26 and the gear transmission mechanism 28 without passing through the belt-driven CVT 24. Then, it is further transmitted from the output shaft 30 to the left and right drive wheels 20L and 20R via the reduction gear assembly 32 and the differential gear assembly 18.

[0040] Thus, the automatic transmission 16 of this embodiment includes: a first power transmission path TP1 that transmits the output of the engine 12 from the input shaft 22 to the output shaft 30 via the forward / reverse switching device 26 and the gear transmission mechanism 28; and a second power transmission path TP2 that transmits the output of the engine 12 from the input shaft 22 to the output shaft 30 via the belt-driven continuously variable transmission 24. These power transmission paths TP1 and TP2 are switched according to the vehicle's driving state. Therefore, the automatic transmission 16 includes a forward clutch C1 for connecting or disconnecting (connecting / disconnecting) the power transmission in the first power transmission path TP1, a reverse brake B1, and a belt-driven clutch C2 for connecting or disconnecting the power transmission in the second power transmission path TP2. On the first power transmission path TP1, a synchronously engaged clutch S1 is also provided in series with respect to the forward / reverse switching device 26 and the gear transmission mechanism 28; specifically, the synchronously engaged clutch S1 is provided downstream of them. The gear transmission mechanism 28 is equivalent to a gear transmission device set in the first power transmission path TP1. The forward clutch C1 is equivalent to a hydraulic gear forward friction engagement device, the reverse brake B1 is equivalent to a hydraulic gear reverse friction engagement device, the driving clutch C2 is equivalent to a hydraulic driving friction engagement device, and the synchronous engagement clutch S1 is equivalent to a hydraulic synchronous engagement device. In this embodiment, the driving clutch C2 is a forward engagement device, and the reverse brake B1 is a reverse engagement device.

[0041] The forward / reverse switching device 26 is mainly composed of a planetary gear device with two pinions. The planetary gear carrier 26c is integrally connected to the input shaft 22, and the sun gear 26s is connected to the small diameter gear 42, which is coaxial with and rotatable relative to the input shaft 22. On the other hand, the ring gear 26r is selectively stopped from rotating by the reverse brake B1, and the planetary gear carrier 26c and the sun gear 26s are selectively connected by the forward clutch C1. Moreover, when the forward clutch C1 is engaged and the reverse brake B1 is released, the input shaft 22 and the small diameter gear 42 are directly connected to achieve forward power transmission. When the first power transmission path TP1 is established by engaging the synchronous engagement clutch S1, forward travel is possible. On the other hand, when the reverse brake B1 is engaged and the forward clutch C1 is released, the small-diameter gear 42 rotates in the opposite direction relative to the input shaft 22, thus entering a reverse power transmission state. When the first power transmission path TP1 is established by engaging the synchronous engagement clutch S1, reverse travel is possible. Furthermore, when both the forward clutch C1 and the reverse brake B1 are released, a neutral state is established, cutting off the power transmission via the first power transmission path TP1.

[0042] The aforementioned forward clutch C1 and reverse brake B1 are both multi-plate hydraulic friction engagement devices that use hydraulic cylinders to engage multiple friction components. The C1 engagement hydraulic pressure Pc1 and B1 engagement hydraulic pressure Pb1 supplied to the hydraulic cylinders are controlled by the first hydraulic control valve SL1 and the lock-up hydraulic control valve SLU (see reference) located in the hydraulic operation control unit 72. Figure 2 These are respectively pressure-controlled, thereby continuously adjusting their engagement force, i.e., the torque transmission capacity. The first hydraulic control valve SL1 and the locking hydraulic control valve SLU are both linear solenoid valves for hydraulic control. The output hydraulic pressures Psl1 and Pslu are electrically controlled by the electronic control device 80, thereby regulating the C1 engagement hydraulic pressure Pc1 and the B1 engagement hydraulic pressure Pb1. In this embodiment, the output hydraulic pressures Psl1 and Pslu are directly supplied to the forward clutch C1 and the reverse brake B1 as the C1 engagement hydraulic pressure Pc1 and the B1 engagement hydraulic pressure Pb1, respectively.

[0043] The gear transmission mechanism 28 includes: a small-diameter gear 42; a large-diameter gear 46 that is non-rotatably mounted on the intermediate shaft 44 and meshes with the small-diameter gear 42; and a small-diameter idler gear 48 that is coaxial with the intermediate shaft 44 and rotatable relative to it. Furthermore, a synchronized engagement clutch S1 is provided between the intermediate shaft 44 and the idler gear 48 to connect or disconnect the power transmission between them. The synchronized engagement clutch S1 includes a synchronizer locking ring and other synchronized engagement mechanisms (synchronization mechanisms), which engage when the clutch hub sleeve 50 is moved by a hydraulic cylinder (not shown). Figure 1When the clutch moves to the left, i.e., in the connecting direction, the idler gear 48 and the intermediate shaft 44 rotate synchronously via the synchronizer locking ring. When the clutch hub sleeve 50 moves further, the idler gear 48 is connected to the intermediate shaft 44 without relative rotation via the spline teeth provided on the inner circumferential surface of the clutch hub sleeve 50. This is achieved by the first hydraulic control valve SL1 (refer to...) provided in the hydraulic operation control unit 72. Figure 2 The S1 engagement hydraulic pressure Ps1, obtained through pressure regulation control, is supplied to the hydraulic cylinder of the synchronous engagement clutch S1, and the synchronous engagement clutch S1 is synchronously engaged based on this S1 engagement hydraulic pressure Ps1. Additionally, the line pressure PL is directly supplied to the hydraulic cylinder of the synchronous engagement clutch S1 as the S1 engagement hydraulic pressure Ps1, and the synchronous engagement clutch S1 is maintained in the engaged state. The line pressure PL is regulated, for example, based on the accelerator operation amount Acc, which is the output requirement, and the throttle opening θth, which corresponds to the engine torque. The first hydraulic control valve SL1 regulates the S1 engagement hydraulic pressure Ps1 by electrically controlling the output hydraulic pressure Psl1 through the electronic control device 80. In this embodiment, the output hydraulic pressure Psl1 is directly supplied to the synchronous engagement clutch S1 as the S1 engagement hydraulic pressure Ps1.

[0044] The idler gear 48 meshes with the large-diameter gear 58 located on the output shaft 30. By engaging either the forward clutch C1 or the reverse brake B1 and connecting the synchronous engagement clutch S1, the output of the engine 12 is transmitted from the input shaft 22 sequentially through the forward / reverse switching device 26, the gear transmission mechanism 28, the idler gear 48, and the large-diameter gear 58 to the output shaft 30, thus establishing the first power transmission path TP1. It should be noted that speed change (deceleration) also occurs between the small-diameter idler gear 48 and the large-diameter gear 58, and they can also be considered as including each other to constitute the gear transmission mechanism 28.

[0045] The belt-type continuously variable transmission 24 includes: a primary pulley 60 disposed on the input shaft 22 and having a variable effective diameter; a secondary pulley 64 disposed on a rotating shaft 62 coaxial with the output shaft 30 and having a variable effective diameter; and a transmission belt 66 wound between the pair of variable pulleys 60 and 64, through which power is transmitted via friction between the pair of variable pulleys 60 and 64 and the transmission belt 66. The pair of variable pulleys 60 and 64 each have hydraulic cylinders 60c and 64c as hydraulic actuators that apply thrust to change the width of the V-groove. The primary hydraulic pressure Ppri supplied to the hydraulic cylinder 60c is controlled by a primary hydraulic control valve SLP (see reference 72). Figure 2The transmission belt 66 is controlled by the variable pulleys 60 and 64, thereby changing the winding diameter (effective diameter) of the transmission belt 66 and continuously varying the gear ratio γ2. For example, the primary hydraulic pressure Ppri is controlled by the primary hydraulic control valve SLP so that the rotational speed of the primary pulley 60, i.e., the rotational speed (input speed) Nin of the input shaft 22, becomes a predetermined target speed corresponding to the gear ratio γ2. Furthermore, the secondary hydraulic pressure Psec supplied to the hydraulic cylinder 64c is controlled by the secondary hydraulic control valve SLS (see reference 72). Figure 2 Pressure regulation control is performed to adjust the belt clamping pressure in a way that prevents slippage of the transmission belt 66. The primary hydraulic control valve SLP and the secondary hydraulic control valve SLS are both linear solenoid valves for hydraulic control, which are electrically controlled by the electronic control device 80 to regulate the pressure of the primary hydraulic Ppri and the secondary hydraulic Psec, respectively.

[0046] The output shaft 30 is configured to be coaxial with and rotatable relative to the rotating shaft 62, and the power transmission between the output shaft 30 and the secondary pulley 64 is connected or disconnected by the belt-driven clutch C2 disposed between the output shaft 30 and the secondary pulley 64. When the belt-driven clutch C2 is engaged, the output of the engine 12 is transmitted from the input shaft 22 to the output shaft 30 via the belt-driven continuously variable transmission 24, establishing the second power transmission path TP2 and enabling forward movement. The belt-driven clutch C2 is a multi-plate friction engagement device that uses a hydraulic cylinder to engage multiple friction elements. The engagement hydraulic pressure Pc2 supplied to the hydraulic cylinder is controlled by a second hydraulic control valve SL2 (see reference 1) located in the hydraulic operation control unit 72. Figure 2 The pressure is adjusted to continuously regulate the engagement force, i.e., the torque transmission capacity. The second hydraulic control valve SL2 is a linear solenoid valve for hydraulic control. The output hydraulic pressure Psl2 is electrically controlled by the electronic control device 80, thereby regulating the engagement hydraulic pressure Pc2 of C2. In this embodiment, the output hydraulic pressure Psl2 is directly supplied to the clutch C2 for driving as the engagement hydraulic pressure Pc2 of C2.

[0047] In this vehicle power transmission device 10, the gear ratio γ1 of the first power transmission path TP1, determined by the gear ratio of the gear transmission mechanism 28, is greater than the maximum value γ2max of the gear ratio γ2 of the second power transmission path TP2. When the vehicle starts or operates under high load, it travels in gear mode using the first power transmission path TP1. As the vehicle speed V increases or the required driving force decreases, it switches to drive mode using the second power transmission path TP2. The mode switch (upshift) from gear mode to drive mode is performed by releasing the forward clutch C1 and engaging the drive clutch C2 via a clutch-to-clutch shift. Similarly, the mode switch (downshift) from drive mode to gear mode is performed by releasing the drive clutch C2 and engaging the forward clutch C1 via a clutch-to-clutch shift. The gear ratios γ1 and γ2 are the ratios (Nin / Nout) of the input speed Nin to the output speed (the speed of the output shaft 30). Both gear ratios γ1 and γ2max are greater than 1.0, causing the output shaft 30 to rotate at a reduced speed relative to the input shaft 22. The output speed Nout corresponds to the vehicle speed V, and the input speed Nin is consistent with the turbine speed Nt.

[0048] Here, as Figure 2 As shown, in addition to the hydraulic control valves SLP, SLS, SLU, SL1, and SL2, the hydraulic control circuit 70 is also equipped with switching solenoid valves SC1, SC2, and SC3, a first switching valve 110, a second switching valve 112, a third switching valve 114, a fault switching valve 116, and a primary pulley control valve (hereinafter referred to as PSCV) 120.

[0049] The first switching valve 110 is a spool valve that switches the oil circuit based on the presence or absence of a signal pressure supplied from the solenoid valve SC1, switching between a first connection state (shown by the solid line) and a second connection state (shown by the dashed line). In the first connection state, the pipeline pressure PL is output as the D-position pressure PD to the second switching valve 112 and the third switching valve 114. In the second connection state, the pipeline pressure PL is output as the R-position pressure PR to the second switching valve 112, and the output hydraulic pressure Pslu of the lock-up hydraulic control valve SLU is output as the fault pressure Pfail to the fault switching valve 116. The D-position pressure PD is used as the initial pressure for the C1 engagement hydraulic pressure Pc1 of the forward clutch C1 and the C2 engagement hydraulic pressure Pc2 of the driving clutch C2, and the R-position pressure PR is used as the initial pressure for the B1 engagement hydraulic pressure Pb1 of the reverse brake B1. In this embodiment, when the solenoid valve SC1 is disconnected (unenergized state) and no signal pressure is supplied, the system is in the first connection state (shown by the solid line) due to the spring force. When the solenoid valve SC1 is connected (energized state) and a signal pressure is supplied, the system is in the second connection state (shown by the dashed line). That is, when the forward driving position (D) is selected via the gear lever 88, the solenoid valve SC1 is disconnected, the first switching valve 110 is in the first connection state, and it outputs the D gear pressure PD. Conversely, when the reverse driving position (R) is selected via the gear lever 88, the solenoid valve SC1 is connected, the first switching valve 110 is in the second connection state, and it outputs the R gear pressure PR. It should be noted that when the N or P gear (which cuts off power transmission) is selected, in this embodiment, the solenoid valve SC1 is connected, and the first switching valve 110 is in the second connection state.

[0050] The second switching valve 112 is a spool valve that switches the oil circuit based on the presence or absence of a signal pressure supplied from the switching solenoid valve SC2, switching between the first connection state shown by the solid line and the second connection state shown by the dashed line. In the first connection state, the D-position pressure PD supplied via the third switching valve 114 when the first switching valve 110 is in the first connection state is output to the fault switching valve 116, the pipeline pressure PL is output to the first hydraulic control valve SL1, and is also output as the fault switching control pressure to the fault switching valve 116. The control hydraulic pressure Psl1 obtained by the pressure adjustment of the first hydraulic control valve SL1 is output as the S1 engagement hydraulic pressure Ps1 to the synchronous engagement clutch S1, and the R-position pressure PR supplied when the first switching valve 110 is in the second connection state is output to the third switching valve 114. In the second connection state, the D-position pressure PD supplied when the first switching valve 110 is in the first connection state is output to the fault switching valve 116. The D-position pressure PD supplied via the third switching valve 114 when the first switching valve 110 is in the first connection state is output to the first hydraulic control valve SL1 and output as the fault switching control pressure to the fault switching valve 116. The control hydraulic pressure Psl1 obtained by the pressure adjustment of the first hydraulic control valve SL1 is output to the fault switching valve 116. The pipeline pressure PL is directly output as the S1 engagement hydraulic pressure Ps1 to the synchronous engagement clutch S1. That is, the control hydraulic pressure Psl1, obtained by adjusting the pipeline pressure PL or the D gear pressure PD as the initial pressure through the first hydraulic control valve SL1, is output to the synchronous engagement clutch S1 as the S1 engagement hydraulic pressure Ps1 in the first connected state. On the other hand, in the second connected state, it is supplied to the forward clutch C1 as the C1 engagement hydraulic pressure Pc1 via the fault switching valve 116. The first hydraulic control valve SL1 is used for the hydraulic control of both the synchronous engagement clutch S1 and the forward clutch C1. In this embodiment, when the switching solenoid valve SC2 is open and no signal pressure is supplied, the first connected state is shown by the solid line according to the spring force, and the second connected state is shown by the dashed line when the switching solenoid valve SC2 is connected and a signal pressure is supplied.

[0051] The third switching valve 114 is a spool valve that switches the oil circuit based on the presence or absence of a signal pressure supplied from the solenoid valve SC3, switching between a first connection state (shown by the solid line) and a second connection state (shown by the dashed line). In the first connection state, the pipeline pressure is output to the lock-up hydraulic control valve SLU, and the control hydraulic pressure Pslu obtained by the pressure adjustment of the lock-up hydraulic control valve SLU is output to the lock-up engagement oil circuit 130, which controls the engagement hydraulic pressure Plu of the lock-up clutch LU. The D-position pressure PD supplied when the first switching valve 110 is in the first connection state is output to the second switching valve 112. In the second connection state, the R-position pressure PR supplied when the first switching valve 110 is in the second connection state and the second switching valve 112 is in the first connection state is output to the lock-up hydraulic control valve SLU, and the control hydraulic pressure Pslu obtained by the pressure adjustment of the lock-up hydraulic control valve SLU is output as the B1 engagement hydraulic pressure Pb1 to the reverse brake B1. That is, the control hydraulic pressure Pslu, obtained by adjusting the pipeline pressure PL or the R gear pressure PR as the initial pressure through the lock-up hydraulic control valve SLU, is output to the lock-up engagement circuit 130 as the control hydraulic pressure for the lock-up engagement hydraulic pressure Plu in the first connected state. On the other hand, in the second connected state, it is supplied to the reversing brake B1 as the B1 engagement hydraulic pressure Pb1. The lock-up clutch LU and the reversing brake B1 use a common lock-up hydraulic control valve SLU for hydraulic control. In this embodiment, when the switching solenoid valve SC3 is open and no signal pressure is supplied, it is in the first connected state shown by the solid line due to the spring force, and when the switching solenoid valve SC3 is connected and a signal pressure is supplied, it is in the second connected state shown by the dashed line.

[0052] The fault switching valve 116 is a spool valve that switches between a first connection state (shown by the solid line) and a second connection state (shown by the dashed line). In the first connection state, the D-position pressure supplied from the second switching valve 112 is output to the second hydraulic control valve SL2 when the first switching valve 110 is in the first connection state and the second switching valve 112 is in the second connection state, and when the first switching valve 110 is in the first connection state, the third switching valve 114 is in the first connection state and the second switching valve 112 is in the first connection state. The control hydraulic pressure Psl1 supplied to the first hydraulic control valve SL1 when the first switching valve 110 is in the first connection state, the third switching valve 114 is in the first connection state and the second switching valve 112 is in the second connection state is output as the C1 engagement hydraulic pressure Pc1 to the forward clutch C1. In the second connection state, the pipeline pressure PL, supplied via a different path than the D gear pressure PD, is output as reverse driving hydraulic pressure Plimp to the second hydraulic control valve SL2. The fault pressure Pfail, supplied when the first switching valve 110 is in the second connection state, is output to the lock-up release circuit 132, which forcibly releases the lock-up clutch LU. That is, the control hydraulic pressure Psl1, obtained by adjusting the D gear pressure PD as the initial pressure through the first hydraulic control valve SL1, is supplied as C1 engagement hydraulic pressure Pc1 to the forward clutch C1 in the first connection state. The hydraulic control of the forward clutch C1 and the synchronous engagement clutch S1 uses a common first hydraulic control valve SL1. The aforementioned lock-up release circuit 132 is also connected to PSCV120. When the fault switching valve 116 is switched to the second connection state and the fault pressure Pfail is supplied to PSCV120, the primary hydraulic pressure Ppri of the belt-driven continuously variable transmission 24 is depressurized through PSCV120, resulting in a larger gear ratio γ2 compared to normal operation.

[0053] When the fault switching valve 116 is supplied with fault pressure Pfail, it is mechanically switched to the second connection state; when the supply of fault pressure Pfail is stopped, the fault switching valve 116 is mechanically switched to the first connection state. However, when the pipeline pressure PL or the D-position pressure PD is supplied from the second switching valve 112 as the fault switching control pressure, the switching to the second connection state based on the fault pressure Pfail is restricted by the action of the pipeline pressure PL or the D-position pressure PD.

[0054] The second hydraulic control valve SL2 is located between the fault switching valve 116 and the driving clutch C2. It uses the D-gear pressure PD or the reversing driving hydraulic pressure Plimp supplied from the fault switching valve 116 as the initial pressure to control the hydraulic pressure. The output hydraulic pressure Psl2, which controls the hydraulic pressure, is supplied to the driving clutch C2 as the C2 engagement hydraulic pressure Pc2. Thus, the driving clutch C2 is engaged and released according to the output hydraulic pressure Psl2 of the second hydraulic control valve SL2, enabling forward driving (driving) based on the second power transmission path TP2 of the belt-driven continuously variable transmission 24.

[0055] Based on this hydraulic control circuit 70, the operating position Lpo of the gear lever 88 can be adjusted accordingly, such as... Figure 3 The diagram shows how multiple power transmission gears P, N, R, and D are activated. Specifically, the gear lever 88 has operating positions Lpo such as D (forward) for driving, R (reverse) for driving, N (neutral) for cutting off power transmission, and P (park) for parking. Furthermore, based on these operating positions Lpo, the electronic control unit 80 controls solenoid valves SC1, SC2, SC3, SL1, SL2, and SLU, switching the engagement / disengagement states of clutches C1, C2, S1, and LU, as well as brake B1, thereby activating different power transmission states for P, N, R, and D gears.

[0056] In the P and N positions, solenoid valves SC1 and SC2 are connected, solenoid valve SC3 is disconnected, and hydraulic control valves SL1, SL2, and SLU are disconnected (hydraulic output stops). Figure 5 This is a hydraulic circuit diagram showing the hydraulic transmission path at this time, represented by thick lines. The first switching valve 110 is in the second connected state, the second switching valve 112 is in the second connected state, the third switching valve 114 is in the first connected state, and the fault switching valve 116 is in the first connected state. Clutches C1 and C2, the reverse brake B1, and the lock-up clutch LU are released, and the synchronous engagement clutch S1 is engaged, resulting in a neutral state where power transmission is cut off. It should be noted that in this embodiment, the second switching valve 112 is in the second connected state, the first hydraulic control valve SL1 is disconnected, and the synchronous engagement clutch S1 is engaged. However, the synchronous engagement clutch S1 can also be released, the second switching valve 112 can be set to the first connected state, or the first hydraulic control valve SL1 can be set to connected.

[0057] In the R position, solenoid valves SC1 and SC3 are connected, solenoid valve SC2 is disconnected, the first hydraulic control valve SL1 and the lock-up hydraulic control valve SLU are connected (hydraulic output), and the second hydraulic control valve SL2 is disconnected. Figure 6 The hydraulic circuit diagram shows the hydraulic transmission path at this time, represented by thick lines. The first switching valve 110 is in the second connection state, the second switching valve 112 is in the first connection state, the third switching valve 114 is in the second connection state, and the fault switching valve 116 is in the first connection state. The reverse brake B1 and the synchronous engagement clutch S1 are engaged, and the clutches C1, C2 and the lock-up clutch LU are released, thus establishing the reverse driving mode in which power is transmitted to the reverse direction via the gear transmission mechanism 28.

[0058] In D gear, the gear driving mode, low-speed driving mode, high-speed driving mode, and fail-safe mode are all available. In gear driving mode, solenoid valves SC1 and SC3 are disconnected, solenoid valve SC2 is connected, the first hydraulic control valve SL1 is connected, and the second hydraulic control valve SL2 is disconnected. Therefore, the first switching valve 110 is in the first connected state, the second switching valve 112 is in the second connected state, the third switching valve 114 is in the first connected state, the fail-safe switching valve 116 is in the first connected state, the forward clutch C1 and the synchronous engagement clutch S1 are engaged, and the driving clutch C2 and the reverse brake B1 are released, enabling gear driving for forward movement via the gear transmission mechanism 28.

[0059] In low-speed driving mode, solenoid valves SC1 and SC3 are disconnected, solenoid valve SC2 is connected, the first hydraulic control valve SL1 is disconnected, and the second hydraulic control valve SL2 is connected. Thus, the first switching valve 110 is in the first connected state, the second switching valve 112 is in the second connected state, the third switching valve 114 is in the first connected state, the fault switching valve 116 is in the first connected state, the driving clutch C2 and the synchronous engagement clutch S1 are engaged, and the forward clutch C1 and the reverse brake B1 are released, enabling forward driving via power transmission through the belt-driven continuously variable transmission 24.

[0060] In the high-speed driving mode, the solenoid valves SC1, SC2, and SC3 are disconnected, the first hydraulic control valve SL1 is disconnected, and the second hydraulic control valve SL2 is connected. Consequently, the first switching valve 110, the second switching valve 112, and the third switching valve 114 are in the first connected state, the fault switching valve 116 is in the first connected state, the driving clutch C2 is engaged, and the forward clutch C1, the reverse brake B1, and the synchronous engagement clutch S1 are released, enabling forward driving via the belt-driven continuously variable transmission 24.

[0061] In the gear driving mode, low-speed driving mode, and high-speed driving mode in D gear, the lock-up hydraulic control valve SLU is connected under certain conditions. Its output hydraulic pressure Pslu adjusts the lock-up engagement hydraulic pressure Plu, thus achieving a lock-up connection where the lock-up clutch LU is fully engaged or slip-engaged. Conversely, when the lock-up hydraulic control valve SLU is disconnected, the lock-up clutch LU is released, resulting in a lock-up disengagement.

[0062] The fail-safe mode is selected when there is a possibility of failure that locks the hydraulic control valve SLU in the hydraulic output state. In this fail-safe mode, solenoid valves SC1 and SC2 are connected, solenoid valve SC3 is disconnected, the first hydraulic control valve SL1 is disconnected, and the second hydraulic control valve SL2 and the lock-up hydraulic control valve SLU are connected. Figure 4 This is a hydraulic circuit diagram showing the hydraulic transmission path at this time, indicated by thick lines. The first switching valve 110 is in the second connection state, the second switching valve 112 is in the second connection state, the third switching valve 114 is in the first connection state, and the fault switching valve 116 is in the second connection state. The belt-driven clutch C2 and the synchronous engagement clutch S1 are engaged, and the forward clutch C1, the reverse brake B1, and the lock-up clutch LU are released, enabling belt-driven travel by transmitting power through the belt-driven continuously variable transmission 24.

[0063] That is, in fail-safe mode, the fail-safe pressure Pfail generated by the output hydraulic pressure Pslu of the lock-up hydraulic control valve SLU is supplied to the fail-safe switching valve 116, thereby switching the fail-safe switching valve 116 to the second connection state shown by the dashed line. The reverse travel hydraulic pressure Plimp is supplied to the second hydraulic control valve SL2, and the belt travel clutch C2 is engaged by the hydraulic control of the second hydraulic control valve SL2, thereby enabling forward travel using the belt continuously variable transmission 24. In addition, the fail-safe pressure Pfail is output from the fail-safe switching valve 116 to the lock-up release oil circuit 132, thereby depressurizing the primary hydraulic pressure Ppri of the belt continuously variable transmission 24 via PSCV 120, increasing the gear ratio γ2, and enabling forward travel with a larger gear ratio γ2 than usual. On the other hand, the output hydraulic pressure Pslu of the lock-up hydraulic control valve SLU is output from the third switching valve 114 in the first connected state to the lock-up engagement oil circuit 130, acting as the control hydraulic pressure for the lock-up engagement hydraulic pressure Plu. However, this pressure is offset by the fault pressure Pfail supplied from the fault switching valve 116 to the lock-up release oil circuit 132, and the lock-up clutch LU is kept in the released state. Therefore, even in the event of a failure where the lock-up hydraulic control valve SLU is actually fixed in the hydraulic output state, the lock-up clutch LU can be kept in the released state for appropriate reverse driving. It should be noted that in this embodiment, the second switching valve 112 is set to the second connected state, the first hydraulic control valve SL1 is disconnected, and the synchronous engagement clutch S1 is engaged. However, the synchronous engagement clutch S1 can also be released, the second switching valve 112 can be set to the first connected state, or the first hydraulic control valve SL1 can be set to connected.

[0064] Such vehicles use a power transmission device 10 as the means of operation. Figure 3The electronic control unit 80 includes controllers for switching between P, R, N, and D gears, switching between multiple driving modes in D gear, shifting of the belt-driven continuously variable transmission 24, and engagement / disengagement control of the lock-up clutch LU. This electronic control unit 80 is configured as a so-called microcomputer, including a CPU, ROM, RAM, and input / output interfaces. It utilizes the temporary storage function of RAM and processes signals according to a program pre-stored in the ROM. Besides supplying the electronic control unit 80 with a signal indicating the operating position (Lpo) of the gear lever 88 from the operating position sensor 90, it also supplies the electronic control unit 80 with various other information required for control, such as signals indicating turbine speed Nt, output speed Nout corresponding to vehicle speed V, and accelerator pedal operation amount (Acc). The accelerator operation amount (Acc) corresponds to the driver's required driving force. The electronic control unit 80 is equivalent to the control device for the vehicle's power transmission device 10, but other controls, such as the output control of the engine 12, can also be performed by the electronic control unit 80.

[0065] The electronic control unit 80 functionally includes a fail-safe control unit 82. When a predetermined anomaly is detected, indicating a possibility of failure where the lock-up hydraulic control valve SLU is fixed in a hydraulic output state, the fail-safe control unit 82 sets up a fail-safe mode that allows forward driving even if the lock-up hydraulic control valve SLU actually fails, when the D gear is selected via the gear lever 88. The lock-up hydraulic control valve SLU controls both the engagement hydraulic pressure Plu of the lock-up clutch LU and the engagement hydraulic pressure Pb1 of the reverse brake B1. Except during reverse driving, the third switching valve 114 is maintained in a first connected state. Therefore, when the lock-up hydraulic control valve SLU fails, the lock-up clutch LU remains engaged except during reverse driving. The engine 12, as the driving force source, is directly connected to the drive wheels 20L and 20R. When the vehicle stops, the rotation of the engine 12 stops, potentially causing the engine to stall. In other words, if the engine stalls when the vehicle stops during forward driving, it can be determined that the lock-up hydraulic control valve SLU may have failed. That is, the aforementioned pre-determined anomaly detection includes situations where the engine stalls when the vehicle stops while moving forward. Failure of the lock-up hydraulic control valve (SLU) can occur due to factors such as short circuits or open wires in the circuit, foreign object intrusion, or malfunction of the valve core, such as a spool valve.

[0066] When the fail-safe control unit 82 is in fail-safe mode during anomaly detection, it only sets the gear to fail-safe mode if the D gear is selected. If the P, N, or R gears are selected, it operates directly according to normal gear shifting control. Figure 3 The P, N, and R gear positions are shown. For example, when selecting N gear via gear lever 88, according to... Figure 3 Solenoid valves SC1 and SC2 are connected, solenoid valve SC3 is disconnected, and hydraulic control valves SL1, SL2, and SLU are disconnected. At this time, assuming the locking hydraulic control valve SLU is not actually malfunctioning, as described above... Figure 5 As shown, the first switching valve 110 is in the second connection state, the second switching valve 112 is in the second connection state, the third switching valve 114 is in the first connection state, the fault switching valve 116 becomes the first connection state, the clutches C1, C2, the reverse brake B1 and the lock-up clutch LU are released, and the synchronous engagement clutch S1 is engaged, becoming a neutral state where power transmission is cut off.

[0067] On the other hand, in the event that the lock-up hydraulic control valve SLU actually fails, such as Figure 7 As shown, the output hydraulic pressure Pslu of the locking hydraulic control valve SLU is output to the locking engagement circuit 130, and the fault pressure Pfail based on the output hydraulic pressure Pslu is supplied to the fault switching valve 116, which is switched to the second connection state. Thereby, the reversing hydraulic pressure Plimp is supplied to the second hydraulic control valve SL2, and the fault pressure Pfail is output to the locking release circuit 132. That is, although becoming... Figure 4 The fail-safe mode is essentially the same state, but the second hydraulic control valve SL2 is disconnected, which sets the output to stop state, and the driving clutch C2 is released, thus maintaining a neutral state where power transmission is cut off.

[0068] Additionally, when selecting the reverse gear via gear lever 88, according to... Figure 3 Solenoid valves SC1 and SC3 are connected, solenoid valve SC2 is disconnected, hydraulic control valves SL1 and SLU are connected, and the second hydraulic control valve SL2 is disconnected. Therefore, regardless of whether the locking hydraulic control valve SLU is actually malfunctioning, as... Figure 6 As shown, the reverse brake B1 is engaged based on the output hydraulic pressure Pslu of the locking hydraulic control valve SLU supplied from the third switching valve 114, and the synchronous engagement clutch S1 is engaged based on the output hydraulic pressure Psl1 of the first hydraulic control valve SL1 supplied from the second switching valve 112, enabling reverse travel using the gear transmission mechanism 28.

[0069] Thus, in the vehicle power transmission device 10 of this embodiment, when a specified abnormality is detected indicating a possibility of failure of the lock-up hydraulic control valve SLU, it is set to... Figure 4The fail-safe mode shown can be used to drive forward using the belt continuously variable transmission 24, even if the lock-up hydraulic control valve SLU is actually malfunctioning, needless to say, and by keeping the lock-up clutch LU in the released state, it can be used to drive backward appropriately without the engine stalling when the vehicle stops.

[0070] Additionally, when selecting neutral (N) during the fault-safe mode anomaly detection process described above, according to... Figure 3 With solenoid valve SC1 connected, first switching valve 110 set to the second connected state, solenoid valve SC3 disconnected, third switching valve 114 set to the first connected state, lock-up hydraulic control valve SLU disconnected, and second hydraulic control valve SL2 disconnected, in this configuration, if lock-up hydraulic control valve SLU is functioning correctly, then as follows: Figure 5 As shown, by stopping the hydraulic output of the lock-up hydraulic control valve SLU, the fault pressure Pfail supplied to the fault switching valve 116 is also stopped, and the fault switching valve 116 is switched to the first connected state. Thus, the lock-up clutch LU is kept in the released state, preventing engine stalling due to the engine 12 stopping due to the engagement of the lock-up clutch LU when shifting from N to R or D. Furthermore, by setting the fault switching valve 116 to the first connected state, the hydraulic supply from the fault switching valve 116 to the second hydraulic control valve SL2 is cut off. Therefore, even if the second hydraulic control valve SL2 fails and is fixed in the hydraulic output state, the driving clutch C2 will not engage, preventing discomfort to the driver caused by the driving clutch C2 engaging despite being in N position due to a fault in the second hydraulic control valve SL2.

[0071] On the other hand, in the event that the lock-up hydraulic control valve SLU actually fails, such as Figure 7 As shown, based on the fault pressure Pfail generated by the output hydraulic pressure Pslu of the locking hydraulic control valve SLU, the fault switching valve 116 is switched to the second connection state, by... Figure 3 , Figure 4 It can be seen that this is essentially the same state as the fail-safe mode where the lock-up hydraulic control valve SLU is connected. Therefore, the lock-up clutch LU is kept in the released state, preventing engine stalling due to the engine 12 stopping due to the lock-up clutch LU engaging when shifting from N to R or D. Furthermore, hydraulic output is stopped by disengaging the second hydraulic control valve SL2, thereby releasing the driving clutch C2 and placing it in neutral, cutting off power transmission. In other words, this is the same as the case where it is set to neutral by disengaging the second hydraulic control valve SL2 in fail-safe mode.

[0072] Additionally, when selecting the reverse (R) gear during fail-safe mode anomaly detection, according to... Figure 3 Solenoid valve SC1 is connected, first switching valve 110 is set to the second connected state, solenoid valve SC2 is disconnected, second switching valve 112 is set to the first connected state, solenoid valve SC3 is connected, third switching valve 114 is set to the second connected state, lock-up hydraulic control valve SLU is connected, and first hydraulic control valve SL1 is connected. Thus, as... Figure 6 As shown, the reverse brake B1 is engaged and the synchronous engagement clutch S1 is engaged, enabling reverse travel using the gear transmission mechanism 28. In this case, in the N gear position, regardless of whether the lock-up hydraulic control valve SLU is actually malfunctioning, the lock-up clutch LU remains in the released state. Therefore, it is possible to achieve the following effect: when shifting from N gear to R gear, it prevents the engine 12 from stopping due to the engagement of the lock-up clutch LU, thus preventing engine stalling.

[0073] It should be noted that in this embodiment, when detecting an anomaly where the lock-up hydraulic control valve SLU may fail, it is also directly used Figure 3 The N and R gear positions are shown in the diagram, but the normal N and R gear positions can also be determined separately from those used during fault detection.

[0074] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, this is only one implementation method. The present invention can be implemented in various ways with modifications and improvements based on the knowledge of those skilled in the art.

Claims

1. A power transmission device (10) for a vehicle, comprising: A fluid transmission device (14) with a lock-up clutch (LU); and An automatic transmission (16) is disposed between an input shaft (22) and an output shaft (30) that transmit power from a drive source (12) via the fluid transmission device (14). The automatic transmission (16) is equipped with a hydraulic forward engagement device (C2) and a hydraulic reverse engagement device (B1) to enable forward and reverse driving. The vehicle power transmission device (10) is characterized in that, The vehicle power transmission device (10) has a hydraulic control circuit (70), which includes: a first switching valve (110), a third switching valve (114), and a fault switching valve (116) for oil circuit switching; and a lock-up hydraulic control valve (SLU) and a second hydraulic control valve (SL2) for hydraulic control. The first switching valve (110) can switch between a first connection state and a second connection state. In the first connection state, the pipeline pressure (PL) that becomes the initial pressure of various hydraulic systems is output as the D gear pressure (PD) for forward driving. In the second connection state, the control hydraulic pressure (Pslu) of the lock-up hydraulic control valve (SLU) is output as the fault pressure (Pfail) to the fault switching valve (116). The third switching valve (114) can switch between a first connection state and a second connection state. In the first connection state, the control hydraulic pressure (Pslu) of the locking hydraulic control valve (SLU) is output to the locking engagement circuit (130) that controls the engagement hydraulic pressure of the locking clutch (LU). In the second connection state, the control hydraulic pressure (Pslu) of the locking hydraulic control valve (SLU) is output to the retraction engagement device (B1). The fault switching valve (116) can switch between a first connection state and a second connection state. In the first connection state, the D-position pressure (PD) supplied when the first switching valve (110) is in the first connection state is output to the second hydraulic control valve (SL2). In the second connection state, the pipeline pressure (PL) supplied through a different path than the D-position pressure (PD) is output to the second hydraulic control valve (SL2) as hydraulic pressure for reverse travel. The fault pressure (Pfail) supplied when the first switching valve (110) is in the second connection state is output to the lock-up release circuit (132) for forcibly releasing the lock-up clutch (LU). When the fault pressure (Pfail) is supplied, the fault switching valve (116) is mechanically switched to the second connection state. When the fault pressure (Pfail) is stopped, the fault switching valve (116) is mechanically switched to the first connection state. The second hydraulic control valve (SL2) is disposed between the fault switching valve (116) and the forward engagement device (C2). By controlling the D-position pressure (PD) or the reverse driving hydraulic pressure (Plimp) supplied from the fault switching valve (116) and outputting it to the forward engagement device (C2), the valve controls the engagement and release of the forward engagement device (C2). The vehicle power transmission device (10) includes a control device (80) that, upon detecting a predetermined anomaly where there is a possibility of failure in which the lock-up hydraulic control valve (SLU) is fixed in the hydraulic output state, sets the following fail-safe mode: the first switching valve (110) is set to the second connection state, the third switching valve (114) is set to the first connection state, and the fail-safe switching valve (116) is switched to the second connection state based on the fault pressure (Pfail) by the hydraulic output of the lock-up hydraulic control valve (SLU). Thereby, the fault pressure (Pfail) is supplied to the lock-up release circuit (132), the lock-up clutch (LU) is held in the released state, and the forward engagement device (C2) is engaged by the hydraulic control of the second hydraulic control valve (SL2) to enable forward movement. When the control device (80) selects the neutral position to cut off power transmission during the abnormality detection, it sets the first switching valve (110) to the second connection state, sets the third switching valve (114) to the first connection state, stops the hydraulic output of the locking hydraulic control valve (SLU), and stops the hydraulic output of the second hydraulic control valve (SL2).

2. The vehicle power transmission device (10) as described in claim 1, characterized in that, The automatic transmission (16) has a first power transmission path (TP1) and a second power transmission path (TP2) arranged side by side between the input shaft (22) and the output shaft (30). The first power transmission path (TP1) is equipped with a gear transmission device (28), a hydraulic gear forward friction engagement device (C1), and a hydraulic gear reverse friction engagement device (B1). A hydraulic synchronous engagement device (S1) is connected in series with the gear forward friction engagement device (C1) and the gear reverse friction engagement device (B1), enabling forward and reverse movement. On the other hand, the second power transmission path (TP2) is equipped with a belt-type continuously variable transmission (24) and a hydraulic belt-driven friction engagement device (C2), enabling forward movement. The belt-driven friction engagement device (C2) is the forward engagement device (C2), and the gear reverse friction engagement device (B1) is the reverse engagement device (B1). In addition to the first switching valve (110), the third switching valve (114), the fault switching valve (116), the lock-up hydraulic control valve (SLU), and the second hydraulic control valve (SL2), the hydraulic control circuit (70) also includes a second switching valve (112) for oil circuit switching and a first hydraulic control valve (SL1) for hydraulic control. In the second connection state of the first switching valve (110), the pipeline pressure (PL) is output to the second switching valve (112) as the R gear pressure (PR) for reverse driving. In the first connection state of the third switching valve (114), the D-position pressure (PD) supplied when the first switching valve (110) is in the first connection state is output to the second switching valve (112), and the pipeline pressure (PL) is output to the lock-up hydraulic control valve (SLU). On the other hand, in the second connection state of the third switching valve (114), the R-position pressure (PR) supplied via the second switching valve (112) when the first switching valve (110) is in the second connection state is output to the lock-up hydraulic control valve (SLU). The second switching valve (112) can switch between a first connection state and a second connection state. In the first connection state, the D-position pressure (PD) supplied when the first switching valve (110) is in the first connection state and the third switching valve (114) is in the first connection state is output to the fault switching valve (116), the pipeline pressure (PL) is output to the first hydraulic control valve (SL1), the control hydraulic pressure (Psl1) of the first hydraulic control valve (SL1) is output to the synchronous engagement device (S1), and the R-position pressure (P) supplied when the first switching valve (110) is in the second connection state is output to the fault switching valve (116). R) is output to the third switching valve (114). In the second connection state of the second switching valve (112), the D-position pressure (PD) supplied when the first switching valve (110) is in the first connection state is output to the fault switching valve (116). The D-position pressure (PD) supplied when the first switching valve (110) is in the first connection state and the third switching valve (114) is in the first connection state is output to the first hydraulic control valve (SL1). The control hydraulic pressure (Psl1) of the first hydraulic control valve (SL1) is output to the fault switching valve (116), and the pipeline pressure (PL) is output to the synchronous engagement device (S1). In the first connection state of the fault switching valve (116), when the first switching valve (110) is in the first connection state and the second switching valve (112) is in the second connection state, and when the first switching valve (110) is in the first connection state, the third switching valve (114) is in the first connection state and the second switching valve (112) is in the first connection state, the supplied D-position pressure (PD) is output to the second hydraulic control valve (SL2), and the control hydraulic pressure (Psl1) of the first hydraulic control valve (SL1) supplied when the first switching valve (110) is in the first connection state, the third switching valve (114) is in the first connection state and the second switching valve (112) is in the second connection state is output to the gear forward friction engagement device (C1). On the other hand, When the control device (80) selects the reverse gear for reverse driving during the abnormality detection, it sets the first switching valve (110) to the second connection state, sets the second switching valve (112) to the first connection state, sets the third switching valve (114) to the second connection state, sets the locking hydraulic control valve (SLU) to the hydraulic output state, and sets the first hydraulic control valve (SL1) to the hydraulic output state.

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