Vehicle power transmission device

Abstract

To provide a vehicular power transmission device using a linear solenoid valve SLU for executing a plurality of hydraulic controls to change over a clutch apply control valve (CACV) while suppressing an impairment of other hydraulic controls due to an influence of a fail changeover hydraulic pressure for changing over the CACV.SOLUTION: A linear solenoid valve SLU functions to control a lock-up engagement hydraulic pressure, output a fail changeover hydraulic pressure to changeover the CACV, and depressurize a primary hydraulic pressure Ppri using the fail changeover hydraulic pressure, and so the number of components is reduced. On the other hand, during detecting abnormality, output of an ON-OFF solenoid valve SC3 for securing a circulation flow amount in a torque converter is stopped, and after the primary hydraulic pressure Ppri is increased by a linear solenoid valve SLP, the fail changeover hydraulic pressure is output from the linear solenoid valve SLU to change over the CACV, thereby suppressing the impairment of other hydraulic controls due to the influence of the fail changeover hydraulic pressure.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a power transmission device for a vehicle, and particularly to a technique for switching to an emergency driving mode by using solenoid valves used for a plurality of types of hydraulic control when an abnormality is detected.

Background Art

[0002] As a power transmission device for a vehicle, an automatic transmission having a torque converter with a lock-up clutch, a belt-type continuously variable transmission having a primary sheave and a secondary sheave, and a clutch for belt running, and a hydraulic control circuit for controlling the operating states of respective parts of the automatic transmission are widely known. The device described in Patent Document 1 is an example thereof, in which a first power transmission path and a second power transmission path are provided in parallel between an input shaft and an output shaft, a gear-type transmission device, a forward clutch, a reverse brake, and a synchronized engagement clutch are provided in the first power transmission path to enable forward and reverse driving, while a belt-type continuously variable transmission and a clutch for belt running are provided in the second power transmission path to enable forward driving, and it is provided with a hydraulic control circuit for controlling clutches, brakes, and the like of the automatic transmission and the gear ratio of the belt-type continuously variable transmission.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, in such a vehicle power transmission device, various solenoid valves are required to control the hydraulic pressure of a clutch, brake, etc. or to switch the oil passage. From the viewpoint of reducing the number of parts, it is considered to control a plurality of types of hydraulic pressures or switch a switching valve using a common solenoid valve. For example, (a) an automatic transmission having a torque converter with a lock-up clutch, a belt-type continuously variable transmission having a primary sheave and a secondary sheave, and a clutch for belt running, (b) a clutch apply control valve (CACV) that can be switched between a normal position and a fail position where the supply state of the hydraulic oil to the clutch for belt running is different, and is switched to the fail position by a fail switching hydraulic pressure, a solenoid valve for lock-up hydraulic pressure control that executes hydraulic pressure control of the lock-up clutch, a solenoid valve for torque converter circulation control that outputs a circulation control hydraulic pressure for ensuring the circulation flow rate of the hydraulic oil in the torque converter, and a solenoid valve for primary hydraulic pressure control that controls the primary hydraulic pressure supplied to the primary sheave of the belt-type continuously variable transmission according to the gear ratio, a hydraulic control circuit provided with, and (c) a control device that, when detecting a predetermined abnormality, switches the CACV to the fail position by the fail switching hydraulic pressure and sets a retreat running mode in which the vehicle runs using the clutch for belt running and the belt-type continuously variable transmission. In a vehicle power transmission device having, (d) output the fail switching hydraulic pressure from the solenoid valve for lock-up hydraulic pressure control, and (e) it is conceivable to configure the hydraulic control circuit such that when the CACV is switched to the fail position, the primary hydraulic pressure is reduced by the output of the fail switching hydraulic pressure from the CACV.

[0005] That is, the solenoid valve for lock-up hydraulic control not only performs hydraulic control of the lock-up clutch, but is also used for fail-safe control that outputs a fail-switching hydraulic pressure to switch the CACV, and has a function of reducing the primary hydraulic pressure by the fail-switching hydraulic pressure. In this case, when the fail-switching hydraulic pressure is output to switch the CACV, the primary hydraulic pressure is reduced. Depending on the magnitude of the fail-switching hydraulic pressure, there is a concern that belt slip may occur. Also, if the primary hydraulic pressure is increased in advance by the solenoid valve for primary hydraulic control in order to prevent belt slip, the belt-type continuously variable transmission may upshift. Further, since the fail-switching hydraulic pressure is also output to the hydraulic control side of the lock-up clutch, if the circulation control hydraulic pressure is output from the solenoid valve for torque converter circulation control in order to ensure the circulation flow rate of the working oil in the torque converter, the hydraulic pressure in the torque converter may become too high.

[0006] The present invention has been made against the background of the above circumstances, and an object thereof is to suppress the impairment of other hydraulic controls due to the influence of the fail-switching hydraulic pressure for switching the CSCV when switching the CACV using a solenoid valve for lock-up hydraulic control that performs a plurality of types of hydraulic controls.

Means for Solving the Problems

[0007] In order to achieve such an object, a first invention includes (a) an automatic transmission including a torque converter with a lock-up clutch, a belt-type continuously variable transmission having a primary sheave and a secondary sheave, and a clutch for belt running, and (b) the working oil for the clutch for belt running The original pressure of the linear solenoid valve for pressure regulationA clutch apply control valve (hereinafter referred to as CACV) that can be switched between different normal positions and fail positions and is switched to the fail position by fail switching hydraulic pressure, a lock-up hydraulic control solenoid valve that executes hydraulic control of the lock-up clutch, a torque converter circulation control solenoid valve that outputs a circulation control hydraulic pressure for ensuring a circulation flow rate of the hydraulic fluid in the torque converter, and a primary hydraulic control solenoid valve that controls the primary hydraulic pressure supplied to the primary sheave according to the gear ratio. A hydraulic control circuit comprising: (c) a control device that, when detecting a predetermined abnormality, switches the CACV to the fail position by the fail switching hydraulic pressure and sets a retreat running mode in which the vehicle runs using the belt running clutch and the belt-type continuously variable transmission; In a vehicle power transmission device having: (d) the fail switching hydraulic pressure is output from the lock-up hydraulic control solenoid valve; (e) the hydraulic control circuit is configured such that when the CACV is switched to the fail position, the fail switching hydraulic pressure is output from the CACV to reduce the primary hydraulic pressure; (f) the control device, when detecting the abnormality, determines whether or not the torque converter circulation control solenoid valve is in an output stop state in which the output of the circulation control hydraulic pressure is stopped, and after determining that it is in the output stop state, increases the primary hydraulic pressure by the primary hydraulic control solenoid valve, and determines whether or not the increase in the primary hydraulic pressure is completed. After determining that the increase in the primary hydraulic pressure is completed, the fail switching hydraulic pressure is output from the lock-up hydraulic control solenoid valve to switch the CACV to the fail position.

[0008] The second invention is the vehicle power transmission device of the first invention, wherein in the automatic transmission, a first power transmission path and a second power transmission path are provided in parallel between an input shaft and an output shaft to which power is transmitted from the torque converter. A gear type transmission, a forward clutch, a reverse brake, and a synchronized engagement clutch are provided in the first power transmission path to enable forward and reverse driving. On the other hand, a belt type continuously variable transmission and a belt running clutch are provided in the second power transmission path to enable forward driving. This is the characteristic.

[0009] The third invention is the vehicle power transmission device of the second invention, wherein (a) the hydraulic control circuit can be switched between a state in which a D range pressure serving as the source pressure of the engagement hydraulic pressure of the forward clutch and the belt running clutch is output and a state in which an R range pressure serving as the source pressure of the engagement hydraulic pressure of the reverse brake is output. In the state where the R range pressure is output, an ON-OFF solenoid valve SC1 that allows the fail switching hydraulic pressure output from the lock-up hydraulic pressure control solenoid valve to be supplied to the clutch apply control valve; (a-2) an ON-OFF solenoid valve SC2 that switches the supply state of the hydraulic pressure to the synchronized engagement clutch; (a-3) a lock-up control position where the hydraulic pressure output from the lock-up hydraulic pressure control solenoid valve is used for the hydraulic pressure control of the lock-up clutch, and a brake control position where the hydraulic pressure output from the lock-up hydraulic pressure control solenoid valve is used for the hydraulic pressure control of the reverse brake. A lock-up / brake switching valve that enables the lock-up hydraulic pressure control solenoid valve to be used for the hydraulic pressure control of the reverse brake in addition to the hydraulic pressure control of the lock-up clutch; (a-4) an ON-OFF solenoid valve SC3 that switches the lock-up / brake switching valve between the lock-up control position and the brake control position and also serves as the torque converter circulation control solenoid valve. In addition, (a-5) in the state where the CACV is held at the normal position, the D range pressure is output from the CACV to the belt running clutch As the original pressure of the linear solenoid valve for regulating the hydraulic oil for When it is output and switched to the fail position, the hydraulic pressure for emergency running supplied to the CACV through a path different from the D-range pressure is applied to the belt running clutch. As the original pressure of the linear solenoid valve for regulating the hydraulic oil for It is configured to be output, and (b) after the control device determines that the boosting of the primary hydraulic pressure by the primary hydraulic pressure control solenoid valve is completed, the control device outputs the fail switching hydraulic pressure from the lock-up hydraulic pressure control solenoid valve and switches the ON-OFF solenoid valve SC1 to a state in which the R-range pressure is output, thereby switching the CACV to the fail position.

Effect of the Invention

[0010] In such a vehicle power transmission device, the lock-up hydraulic pressure control solenoid valve is used not only for hydraulic pressure control of the lock-up clutch but also for fail-safe control to output a fail switching hydraulic pressure and switch the CACV, and since it has a function of reducing the primary hydraulic pressure by the fail switching hydraulic pressure, the number of components can be reduced and the hydraulic pressure control circuit can be configured inexpensively and compactly.

[0011] When an abnormality is detected, after the solenoid valve for torque converter circulation control enters an output stop state where it stops the output of the circulation control hydraulic pressure, the primary hydraulic pressure control solenoid valve increases the primary hydraulic pressure. After the increase in the primary hydraulic pressure is completed, a failover hydraulic pressure is output from the lock-up hydraulic pressure control solenoid valve to switch the CACV to the fail position. Therefore, it is suppressed that other hydraulic pressure controls are impaired by the influence of the failover hydraulic pressure. That is, when the failover hydraulic pressure is output from the lock-up hydraulic pressure control solenoid valve, the solenoid valve for torque converter circulation control is surely in the output stop state, and there is no fear that the flow rate will increase to secure the circulation flow rate. Therefore, it is suppressed that the hydraulic pressure in the torque converter becomes too high when the failover hydraulic pressure is supplied to the hydraulic pressure control side of the lock-up clutch. Also, since the primary hydraulic pressure control solenoid valve increases the primary hydraulic pressure prior to the reduction of the primary hydraulic pressure by the failover hydraulic pressure, it is suppressed that belt slip occurs due to the reduction of the primary hydraulic pressure by the failover hydraulic pressure. Moreover, the increase in the primary hydraulic pressure by the primary hydraulic pressure control solenoid valve is just before the failover hydraulic pressure is output from the lock-up hydraulic pressure control solenoid valve to switch the CACV to the fail position. Therefore, it is suppressed that the belt-type continuously variable transmission upshifts due to the increase in the primary hydraulic pressure.

[0012] In the second and third inventions, a first power transmission path and a second power transmission path are provided in parallel between the input shaft and the output shaft. A gear type transmission, a forward clutch, a reverse brake, and a synchronized engagement clutch are provided in the first power transmission path to enable forward and reverse travel. On the other hand, in the second power transmission path, a belt type continuously variable transmission and a clutch for belt travel are provided, and when an automatic transmission capable of forward travel is provided, by assigning a plurality of functions to the solenoid valve for lock-up hydraulic control, the number of parts can be reduced and the hydraulic control circuit can be configured inexpensively and compactly, and the effect can be appropriately obtained. Further, when the procedure for outputting the fail-switching hydraulic pressure from the solenoid valve for lock-up hydraulic control and switching the CACV to the fail position at the time of abnormality detection is performed as in the first invention, the effect that other hydraulic controls are prevented from being impaired by the influence of the fail-switching hydraulic pressure can be appropriately obtained.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiment for Carrying Out the Invention

[0014] The present invention is suitably applied to a vehicle power transmission device for an engine-driven vehicle equipped with an engine (internal combustion engine) as a driving force source, but can also be applied to a hybrid vehicle equipped with an engine and an electric motor as driving force sources, an electric vehicle equipped only with an electric motor as a driving force source, and the like. As the hydraulic control solenoid valve such as the lock-up hydraulic control solenoid valve and the primary hydraulic control solenoid valve, for example, a linear solenoid valve that continuously changes the output hydraulic pressure according to the excitation current is suitable, but those that continuously change the hydraulic pressure by proportional control or the like may also be used. As the solenoid valve for torque converter circulation control, an ON-OFF solenoid valve is suitable, but a linear solenoid valve can also be used. The ON-OFF solenoid valve such as the ON-OFF solenoid valve SC1 may control the output state of a predetermined hydraulic pressure by the solenoid valve itself or switch the connection state of the oil passage, or may switch the connection state of the oil passage via a switching valve such as a spool valve by the signal pressure output from the solenoid valve. Regarding the hydraulic control solenoid valve, the solenoid valve itself may control a predetermined hydraulic pressure, or it may control the hydraulic pressure via a hydraulic control valve or the like according to the output hydraulic pressure of the solenoid valve.

[0015] An automatic transmission, for example, has a first power transmission path and a second power transmission path provided in parallel between an input shaft and an output shaft. The first power transmission path is provided with a gear transmission device, a forward clutch, a reverse brake, and a synchronized engagement clutch, enabling forward and reverse driving. On the other hand, the second power transmission path is provided with a belt-type continuously variable transmission and a belt driving clutch, enabling forward driving. Such an automatic transmission is preferably used. However, it only needs to be equipped with at least a torque converter with a lock-up clutch, a belt-type continuously variable transmission, and a belt driving clutch, and various embodiments are possible. For example, it may be simply connected in series with a torque converter, a belt-type continuously variable transmission, and a forward and reverse switching device having a forward clutch and a reverse brake. In that case, for example, the forward clutch can be used as a belt driving clutch to which the hydraulic pressure for retreat driving is supplied when an abnormality is detected.

Embodiment

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are appropriately simplified or deformed for the purpose of explanation, and the dimensional ratios, shapes, etc. of each part are not necessarily accurately drawn.

[0017] FIG. 1 is a schematic diagram for explaining the schematic configuration of a vehicle power transmission device 10 according to an embodiment of the present invention, and is a diagram shown by expanding so that a plurality of mutually parallel axes are located in one plane. This vehicle power transmission device 10 is a transverse type suitably adopted for an FF (front engine · front drive) type vehicle. The output of an engine 12 as a driving power source for traveling is transmitted from a torque converter 14 as a fluid transmission device to a differential gear device 18 via an automatic transmission 16, and is distributed to 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, and transmits power via a fluid (hydraulic oil). At the same time, it is directly connected via a lock-up clutch LU. A mechanical oil pump 74 is provided on the pump impeller 14p, and is rotationally driven by the engine 12 to output hydraulic pressure, and is used as a hydraulic pressure source of a hydraulic control circuit 70 shown by a broken line. The connection destination, that is, the arrangement position of the oil pump 74 can be appropriately changed, and an electric oil pump can also be adopted.

[0018] FIG. 2 specifically illustrates a main part of the hydraulic control circuit 70, that is, a hydraulic operation control unit 72 constituted by a valve body or the like. A lock-up engagement hydraulic pressure Plu, which is an engagement hydraulic pressure of the lock-up clutch LU of the torque converter 14, is pressure-regulated and controlled by a linear solenoid valve SLU, and the lock-up clutch LU is controlled for engagement and release according to this lock-up engagement hydraulic pressure Plu. The lock-up engagement hydraulic pressure Plu controls, for example, the differential pressure between a lock-up engagement side oil chamber and a lock-up release side oil chamber. The linear solenoid valve SLU is a solenoid valve for hydraulic control, and the lock-up engagement hydraulic pressure Plu is pressure-regulated by electrically controlling an output hydraulic pressure Pslu by an electronic control device 80. This linear solenoid valve SLU corresponds to a solenoid valve for lock-up hydraulic pressure control.

[0019] The automatic transmission 16 includes an input shaft 22 provided integrally with a turbine shaft which is an output rotating member of the torque converter 14, a belt-type continuously variable transmission 24 connected to the input shaft 22, a forward and reverse switching device 26 and a gear transmission mechanism 28 also connected to the input shaft 22 and provided in parallel with the belt-type continuously variable transmission 24, an output shaft 30 which is a common output rotating member of the belt-type continuously variable transmission 24 and the gear transmission mechanism 28, and a reduction gear device 32. A small-diameter gear 34 of the reduction gear device 32 meshes with a ring gear 36 of the differential gear device 18. In the automatic transmission 16 configured in this way, the output of the engine 12 is transmitted from the torque converter 14 to the output shaft 30 via the belt-type continuously variable transmission 24, or is transmitted to the output shaft 30 via the forward and reverse switching device 26 and the gear transmission mechanism 28 without passing through the belt-type continuously variable transmission 24. Then, it is transmitted from the output shaft 30 to the left and right drive wheels 20L and 20R through the reduction gear device 32 and the differential gear device 18.

[0020] 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 and 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-type continuously variable transmission 24. The power transmission paths TP1 and TP2 are switched according to the running state of the vehicle. For this reason, the automatic transmission 16 includes a forward clutch C1 that connects and disconnects (connects and shuts off) the power transmission in the first power transmission path TP1, a reverse brake B1, and a belt running clutch C2 that connects and disconnects the power transmission in the second power transmission path TP2. Further, in the first power transmission path TP1, a synchronized engagement clutch S1 is provided in series with, specifically, on the downstream side of, the forward and reverse switching device 26 and the gear transmission mechanism 28. The gear transmission mechanism 28 corresponds to a gear-type transmission device provided in the first power transmission path TP1.

[0021] The forward and reverse switching device 26 is mainly composed of a double pinion type planetary gear device. The carrier 26c is integrally connected to the input shaft 22, and the sun gear 26s is connected to a small diameter gear 42 arranged coaxially and rotatably relative to the input shaft 22. On the other hand, the ring gear 26r is selectively rotated and stopped via the reverse brake B1, and the carrier 26c and the sun gear 26s are selectively connected via the forward clutch C1. When the forward clutch C1 is engaged and the reverse brake B1 is released, the input shaft 22 is directly connected to the small diameter gear 42 and enters the forward power transmission state. When the first power transmission path TP1 is established by the engagement of the synchronized meshing clutch S1, forward running becomes possible. On the other hand, when the reverse brake B1 is engaged and the forward clutch C1 is released, the small diameter gear 42 is rotated in the reverse direction with respect to the input shaft 22, so that it enters the reverse power transmission state. When the first power transmission path TP1 is established by the engagement of the synchronized meshing clutch S1, reverse running becomes possible. Also, when both the forward clutch C1 and the reverse brake B1 are released, it becomes a neutral state that cuts off the power transmission through the first power transmission path TP1.

[0022] Both the forward clutch C1 and the reverse brake B1 are multi-plate hydraulic friction engagement devices in which a plurality of friction materials are frictionally engaged by a hydraulic cylinder. The C1 engagement hydraulic pressure Pc1 and the B1 engagement hydraulic pressure Pb1 supplied to the hydraulic cylinder are pressure-regulated and controlled by linear solenoid valves SL1 and SLU provided in the hydraulic operation control unit 72, respectively, so that their engagement forces, that is, the transmission torque capacity, are continuously adjusted. The linear solenoid valves SL1 and SLU are solenoid valves for hydraulic control. The output hydraulic pressures Psl1 and Pslu are electrically controlled by the electronic control device 80, respectively, to regulate 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.

[0023] The gear transmission mechanism 28 includes a small-diameter gear 42, a large-diameter gear 46 that is provided non-rotatably relative to the countershaft 44 and meshes with the small-diameter gear 42, and a small-diameter idler gear 48 that is provided coaxially and rotatably relative to the countershaft 44. A synchromesh clutch S1 is provided between the countershaft 44 and the idler gear 48, and the power transmission between them is disconnected and connected. The synchromesh clutch S1 includes a synchronizing mechanism (synchronization mechanism) such as a synchronizer ring. When the clutch hub sleeve 50 is moved in the connection direction, which is the left direction in FIG. 1, by a hydraulic cylinder (not shown), the idler gear 48 is synchronously rotated with the countershaft 44 via the synchronizer ring. When the clutch hub sleeve 50 is further moved, the idler gear 48 is non-rotatably connected to the countershaft 44 via spline teeth provided on the inner peripheral surface of the clutch hub sleeve 50. The hydraulic cylinder of the synchromesh clutch S1 is supplied with an S1 engagement hydraulic pressure Ps1 that is pressure-regulated by a linear solenoid valve SL1 provided in the hydraulic operation control unit 72. The synchromesh clutch S1 is synchronously engaged based on the S1 engagement hydraulic pressure Ps1. The hydraulic cylinder of the synchromesh clutch S1 is also supplied with the line hydraulic pressure PL as the S1 engagement hydraulic pressure Ps1 as it is, so that the synchromesh clutch S1 is maintained in the engaged state. The line hydraulic pressure PL is pressure-regulated according to, for example, the accelerator operation amount Acc, which is the output required amount, and the throttle valve opening θth corresponding to the engine torque. The linear solenoid valve SL1 pressure-regulates the S1 engagement hydraulic pressure Ps1 by electrically controlling the output hydraulic pressure Psl1 by the electronic control device 80. In this embodiment, the output hydraulic pressure Psl1 is directly supplied to the synchromesh clutch S1 as the S1 engagement hydraulic pressure Ps1.

[0024] The idler gear 48 is meshed with a large-diameter gear 58 provided on the output shaft 30. When either one of the forward clutch C1 and the reverse brake B1 is engaged and the synchronized meshing clutch S1 is connected, the output of the engine 12 is transmitted from the input shaft 22 to the output shaft 30 via the forward / reverse switching device 26, the gear transmission mechanism 28, the idler gear 48, and the large-diameter gear 58 in sequence, and the first power transmission path TP1 is established. Note that speed change (deceleration) is also performed between the small-diameter idler gear 48 and the large-diameter gear 58, and the gear transmission mechanism 28 can also be regarded as being constituted including these components.

[0025] The belt-type continuously variable transmission 24 includes a primary sheave 60 with a variable effective diameter provided on the input shaft 22, a secondary sheave 64 with a variable effective diameter provided on a rotating shaft 62 coaxial with the output shaft 30, and a transmission belt 66 wound between the pair of variable sheaves 60 and 64. Power transmission is performed through the friction between the pair of variable sheaves 60 and 64 and the transmission belt 66. The pair of variable sheaves 60 and 64 each include hydraulic cylinders 60c and 64c as hydraulic actuators that apply a thrust to change the V-groove width. The primary hydraulic pressure Ppri supplied to the hydraulic cylinder 60c is controlled by a linear solenoid valve SLP provided in the hydraulic operation control unit 72. As a result, the V-groove widths of both variable sheaves 60 and 64 change, the wrap diameter (effective diameter) of the transmission belt 66 is changed, and the transmission ratio γ2 is continuously changed. For example, the primary hydraulic pressure Ppri is controlled by the linear solenoid valve SLP so that the rotational speed of the input shaft 22 (input rotational speed) Nin, which is the rotational speed of the primary sheave 60, becomes a predetermined target rotational speed corresponding to the transmission ratio γ2. Also, the secondary hydraulic pressure Psec supplied to the hydraulic cylinder 64c is pressure-regulated by a linear solenoid valve SLS provided in the hydraulic operation control unit 72, so that the belt clamping pressure is adjusted so that the transmission belt 66 does not slip. The linear solenoid valves SLP and SLS are solenoid valves for hydraulic control, and are electrically controlled by an electronic control device 80 to regulate the primary hydraulic pressure Ppri and the secondary hydraulic pressure Psec, respectively. The linear solenoid valve SLP corresponds to a solenoid valve for primary hydraulic pressure control.

[0026] The output shaft 30 is disposed coaxially and rotatably relative to the rotation shaft 62, and the power transmission between the output shaft 30 and the secondary sieve 64 is disconnected and connected by the belt running clutch C2 provided between the output shaft 30 and the secondary sieve 64. When the belt running clutch C2 is engaged, the output of the engine 12 is transmitted from the input shaft 22 via the belt type continuously variable transmission 24 to the output shaft 30, and the second power transmission path TP2 is established and forward running becomes possible. The belt running clutch C2 is a multi-plate friction engagement device in which a plurality of friction materials are frictionally engaged by a hydraulic cylinder, and the C2 engagement hydraulic pressure Pc2 supplied to the hydraulic cylinder is pressure-regulated by a linear solenoid valve SL2 provided in the hydraulic operation control unit 72, whereby the engagement force, that is, the transmission torque capacity, is continuously adjusted. The linear solenoid valve SL2 is a solenoid valve for hydraulic control, and the C2 engagement hydraulic pressure Pc2 is pressure-regulated by being electrically controlled by the electronic control device 80.

[0027] In such a vehicle power transmission device 10, the gear ratio γ1 of the first power transmission path TP1 determined by the gear ratio etc. of the gear transmission mechanism 28 is larger than the maximum value γ2max of the gear ratio γ2 of the second power transmission path TP2. During vehicle start or high-load running, the vehicle runs in a gear running mode using the first power transmission path TP1, and is switched to a belt running mode using the second power transmission path TP2 as the vehicle speed V increases or the required driving force decreases. The mode shift (upshift) from the gear running mode to the belt running mode is executed by a clutch-to-clutch shift (CtoC) that releases the forward clutch C1 and engages the belt running clutch C2. Also, the mode shift (downshift) from the belt running mode to the gear running mode is executed by a clutch-to-clutch shift that releases the belt running clutch C2 and engages the forward clutch C1. The gear ratios γ1 and γ2 are the ratios (Nin / Nout) of the input rotational speed Nin to the output rotational speed (the rotational speed of the output shaft 30) Nout. Both the gear ratios γ1 and γ2max are larger than 1.0, and the output shaft 30 is rotated at a reduced speed with respect to the input shaft 22. The output rotational speed Nout corresponds to the vehicle speed V, and the input rotational speed Nin coincides with the turbine rotational speed Nt.

[0028] Here, as shown in FIG. 2, the hydraulic control circuit 70 is provided with, in addition to the linear solenoid valves SLP, SLS, SL1, SL2, and SLU, ON-OFF solenoid valves SC1, SC2, SC3, an SC1 switching valve 110, an SC2 switching valve 112, an SC3 switching valve 114, a CACV 116, and a primary sheave control valve (hereinafter referred to as PSCV) 120. The SC1 switching valve 110 is a spool valve that switches the oil passage according to the presence or absence of the signal pressure supplied from the ON-OFF solenoid valve SC1, and outputs the line hydraulic pressure PL as the D-range pressure PD to the SC2 switching valve 112 and the SC3 switching valve 114 in the first connection state shown by the solid line, and outputs the line hydraulic pressure PL as the R-range pressure PR to the SC2 switching valve 112 in the second connection state shown by the broken line. In the second connection state, it is allowed to supply the fail-switching hydraulic pressure Pfail regulated by the linear solenoid valve SLU to the CACV 116. The D-range pressure PD is used as the C1 engagement hydraulic pressure Pc1 of the forward clutch C1 and the C2 engagement hydraulic pressure Pc2 of the belt traveling clutch C2, and the R-range pressure PR is used as the original pressure of the reverse brake B1. In this embodiment, when the ON-OFF solenoid valve SC1 is not energized and no signal pressure is supplied, it is in the first connection state shown by the solid line according to the biasing force of the spring, and when the ON-OFF solenoid valve SC1 is energized and signal pressure is supplied, it is in the second connection state shown by the broken line. That is, when the D range for forward travel is selected by the shift lever 88, the ON-OFF solenoid valve SC1 is not energized, the SC1 switching valve 110 is in the first connection state, and the D-range pressure PD is output. On the other hand, when the R range for reverse travel is selected by the shift lever 88, the ON-OFF solenoid valve SC1 is energized, the SC1 switching valve 110 is in the second connection state, and the R-range pressure PR is output.

[0029] The SC2 switching valve 112 is a spool valve that switches the oil passage according to the presence or absence of the signal pressure supplied from the ON-OFF solenoid valve SC2. As shown by the solid line, the D-range pressure PD supplied from the SC1 switching valve 110 via the SC3 switching valve 114 is output to the CACV 116, the line oil pressure PL is output to the linear solenoid valve SL1, and the output oil pressure Psl1 regulated with the line oil pressure PL as the original pressure by the linear solenoid valve SL1 is output to the synchronized engagement clutch S1 as the S1 engagement oil pressure Ps1. The R-range pressure PR supplied from the SC1 switching valve 110 is output to the SC3 switching valve 114 in the first connection state, and as shown by the broken line, the D-range pressure PD supplied from the SC1 switching valve 110 is output to the CACV 116, the D-range pressure PD supplied from the SC1 switching valve 110 via the SC3 switching valve 114 is output to the linear solenoid valve SL1, the line oil pressure PL is directly output to the synchronized engagement clutch S1 as the S1 engagement oil pressure Ps1, and the output oil pressure Psl1 regulated with the D-range pressure PD as the original pressure by the linear solenoid valve SL1 is output to the CACV 116. That is, the output oil pressure Psl1 regulated with the line oil pressure PL or the D-range pressure PD as the original pressure by the linear solenoid valve SL1 is output to the synchronized engagement clutch S1 as the S1 engagement oil pressure Ps1 in the first connection state, while in the second connection state, it is supplied to the forward clutch C1 as the C1 engagement oil pressure Pc1 via the CACV 116, and the common linear solenoid valve SL1 is used for the hydraulic control of the synchronized engagement clutch S1 and the forward clutch C1. In this embodiment, when the ON-OFF solenoid valve SC2 is not energized and no signal pressure is supplied, it is in the first connection state shown by the solid line according to the biasing force of the spring, and when the ON-OFF solenoid valve SC2 is energized and signal pressure is supplied, it becomes the second connection state shown by the broken line.

[0030] The SC3 switching valve 114 is a spool valve that switches the oil passage according to the presence or absence of the signal pressure supplied from the ON-OFF solenoid valve SC3. As shown by the solid line, it outputs the line hydraulic pressure PL to the linear solenoid valve SLU, and the output hydraulic pressure Pslu regulated with the line hydraulic pressure PL as the original pressure by the linear solenoid valve SLU is output as the control hydraulic pressure for the lock-up engagement hydraulic pressure Plu. It outputs the D-range pressure PD supplied from the SC1 switching valve 110 to the SC2 switching valve 112 in the first connection state. As shown by the broken line, it outputs the R-range pressure PR supplied from the SC1 switching valve 110 via the SC2 switching valve 112 to the linear solenoid valve SLU, and the output hydraulic pressure Pslu regulated with the R-range pressure PR as the original pressure by the linear solenoid valve SLU is output as the B1 engagement hydraulic pressure Pb1 to the reverse brake B1. It can be switched between the two connection states. That is, the output hydraulic pressure Pslu regulated with the line hydraulic pressure PL or the R-range pressure PR as the original pressure by the linear solenoid valve SLU is output as the control hydraulic pressure for the lock-up engagement hydraulic pressure Plu in the first connection state, while it is supplied to the reverse brake B1 as the B1 engagement hydraulic pressure Pb1 in the second connection state. The same linear solenoid valve SLU is used for the hydraulic control of the lock-up clutch LU and the reverse brake B1. In this embodiment, when the ON-OFF solenoid valve SC3 is not energized and no signal pressure is supplied, it is in the first connection state shown by the solid line according to the biasing force of the spring. When the ON-OFF solenoid valve SC3 is energized and signal pressure is supplied, it becomes the second connection state shown by the broken line. The SC3 switching valve 114 corresponds to a lock-up / brake switching valve, the first connection state corresponds to the lock-up control position, and the second connection state corresponds to the brake control position.

[0031] The above ON-OFF solenoid valve SC3 not only switches the SC3 switching valve 114, but also outputs a circulation control hydraulic pressure Ptc under certain predetermined conditions to ensure the circulation flow rate of the hydraulic oil in the torque converter 14 during forward travel when the SC3 switching valve 114 is held in the first connection state. That is, when the lock-up clutch LU is released (lock-up OFF, LU-OFF) when the gear travel mode in the D range, the belt low vehicle speed travel mode, or the belt high vehicle speed travel mode shown in FIG. 3 is selected, or when performing clutch-to-clutch shifting (CtoC) that switches between the gear travel mode and the belt travel mode, the circulation flow rate of the hydraulic oil in the torque converter 14 is increased by outputting the circulation control hydraulic pressure Ptc under certain conditions. The circulation control hydraulic pressure Ptc is the same as the signal pressure for switching the SC3 switching valve 114. However, since the D-range pressure PD is supplied to the SC3 switching valve 114 during forward travel in the D range, the SC3 switching valve 114 is held in the first connection state indicated by the solid line regardless of the output of the circulation control hydraulic pressure Ptc. The ON-OFF solenoid valve SC3 corresponds to a solenoid valve for torque converter circulation control.

[0032] When the SC1 switching valve 110 is in the second connection state, the CACV116 is a spool valve that switches the oil passage by the fail-switching hydraulic pressure Pfail supplied from the linear solenoid valve SLU. As shown by the solid line, the output hydraulic pressure Psl1 of the linear solenoid valve SL1 supplied from the SC2 switching valve 112 is supplied to the forward clutch C1 as the C1 engagement hydraulic pressure Pc1, and the D-range pressure PD supplied from the SC2 switching valve 112 is output to the linear solenoid valve SL2 in the first connection state. As shown by the dashed line, the fail-switching hydraulic pressure Pfail, which is the output hydraulic pressure of the linear solenoid valve SLU supplied from the SC1 switching valve 110, is output to the PSCV120, and the line hydraulic pressure PL is directly output to the linear solenoid valve SL2 as the retreat travel hydraulic pressure Plimp. It can be switched between the two connection states. In the first connection state, the linear solenoid valve SL2 regulates and controls the C2 engagement hydraulic pressure Pc2 using the D-range pressure PD as the source pressure. Accordingly, the belt travel clutch C2 is engaged according to the C2 engagement hydraulic pressure Pc2, and belt travel via the second power transmission path TP2 becomes possible.

[0033] The above-mentioned CACV 116 is normally maintained in the first connection state indicated by a solid line. However, when the retreat running mode in the D range shown in Fig. 3 is selected, both the ON-OFF solenoid valves SC1 and SC2 are excited, so that both the SC1 switching valve 110 and the SC2 switching valve 112 are brought into the second connection state, and the fail-switching hydraulic pressure Pfail output from the linear solenoid valve SLU is supplied, whereby it is switched to the second connection state indicated by a broken line. In this second connection state, since the line hydraulic pressure PL is supplied to the linear solenoid valve SL2 as the retreat running hydraulic pressure Plimp, the linear solenoid valve SL2 regulates and controls the C2 engagement hydraulic pressure Pc2 with the retreat running hydraulic pressure Plimp as the original pressure, so that the belt running clutch C2 is engaged according to the C2 engagement hydraulic pressure Pc2, and belt running by the second power transmission path TP2, that is, belt retreat running becomes possible. Further, in the retreat running mode in which the CACV 116 is brought into the second connection state, the fail-switching hydraulic pressure Pfail is supplied from the CACV 116 to the PSCV 120, whereby the primary hydraulic pressure Ppri of the belt-type continuously variable transmission 24 is reduced by the PSCV 120, and the transmission ratio γ2 is made larger than normal. The first connection state of the CACV 116 corresponds to the normal position, and the second connection state corresponds to the fail position.

[0034] According to such a hydraulic control circuit 70, a plurality of power transmission ranges P, N, R, and D can be established as shown in FIG. 3 according to the operation position Lpo of the shift lever 88. That is, the shift lever 88 includes a D position for selecting the D (drive) range for forward travel, an R position for selecting the R (reverse) range for reverse travel, an N position for selecting the N (neutral) range for cutting off power transmission, a P position for selecting the P (parking) range for parking, etc. as the operation position Lpo. Then, according to these operation positions Lpo, the solenoid valves SC1, SC2, SC3, SL1, SL2, and SLU are respectively controlled by the electronic control unit 80, and the engagement and release states of the clutches C1, C2, S1, and the brake B1, which are engagement devices, are switched, whereby power transmission states different P range, N range, R range, and D range are established. In the P range and the N range, power transmission is cut off by releasing the clutches C1, C2, and the reverse brake B1. In the R range, the reverse brake B1 and the synchronized engagement clutch S1 are engaged and the clutches C1, C2 are released, whereby reverse travel by the first power transmission path TP1 is made possible.

[0035] In the D range, it is possible to select a gear driving mode, a belt low vehicle speed driving mode, a belt high vehicle speed driving mode, and a retraction driving mode. In the gear driving mode, the forward clutch C1 and the synchronized engagement clutch S1 are engaged, and the belt driving clutch C2 and the reverse brake B1 are released, enabling forward driving via the first power transmission path TP1. In the belt low vehicle speed driving mode, the belt driving clutch C2 and the synchronized engagement clutch S1 are engaged, and the forward clutch C1 and the reverse brake B1 are released, enabling forward driving via the second power transmission path TP2. In the belt high vehicle speed driving mode, the belt driving clutch C2 is engaged, and the forward clutch C1, the reverse brake B1, and the synchronized engagement clutch S1 are released, enabling forward driving via the second power transmission path TP2. In the retraction driving mode, the belt driving clutch C2 and the synchronized engagement clutch S1 are engaged, and the forward clutch C1 and the reverse brake B1 are released, enabling forward driving via the second power transmission path TP2. Also, when switching between the gear driving mode and the belt low vehicle speed driving mode, a clutch-to-clutch shift (CtoC) is performed in which one of the forward clutch C1 and the belt driving clutch C2 is released and the other is engaged, and the engagement hydraulic pressure Pc1 of the forward clutch C1 is regulated and controlled by the linear solenoid valve SL1, and the engagement hydraulic pressure Pc2 of the belt driving clutch C2 is regulated and controlled by the linear solenoid valve SL2.

[0036] In the gear driving mode, belt low vehicle speed driving mode, and belt high vehicle speed driving mode of the D range, under certain conditions, the hydraulic pressure Pslu of the linear solenoid valve SLU is output, and the lock-up engagement hydraulic pressure Plu is regulated according to the output hydraulic pressure Pslu, so that the lock-up clutch LU is fully engaged or slip-engaged to achieve lock-up ON (LU-ON). Also, when the hydraulic pressure output from the linear solenoid valve SLU is stopped, the lock-up clutch LU is released to achieve lock-up OFF (LU-OFF). When in that lock-up OFF (LU-OFF), or during clutch-to-clutch shift (CtoC) for switching between the gear driving mode and the belt driving mode, under certain conditions, the circulation control hydraulic pressure Ptc is output from the ON-OFF solenoid valve SC3, increasing the circulation flow rate of the hydraulic oil in the torque converter 14 and ensuring a predetermined circulation flow rate.

[0037] Figure 4 is a hydraulic circuit diagram showing in bold lines the oil passages involved in power transmission when in the retreat driving mode of the D range. In the retreat driving mode, when the fail-switching hydraulic pressure Pfail is output from the linear solenoid valve SLU, the CACV116 is switched to the second connection state shown by the dashed line, and the retreat driving hydraulic pressure Plimp is supplied to the linear solenoid valve SL2 to engage the belt driving clutch C2, enabling forward driving using the belt-type continuously variable transmission 24 of the second power transmission path TP2. Also, when the fail-switching hydraulic pressure Pfail is supplied from the CACV116 to the PSCV120, the primary hydraulic pressure Ppri of the belt-type continuously variable transmission 24 is reduced and the transmission ratio γ2 becomes larger, and forward driving is performed at a transmission ratio γ2 larger than normal. On the other hand, the fail-switching hydraulic pressure Pfail output from the linear solenoid valve SLU is also supplied to the control side of the lock-up engagement hydraulic pressure Plu via the SC3 switching valve 114 in the first connection state, but is offset by the fail-switching hydraulic pressure Pfail output from the CACV116, preventing the engagement of the lock-up clutch LU.

[0038] Such a vehicle power transmission device 10 includes an electronic control unit 80 as a controller that performs shift control of the P range, R range, N range, and D range shown in FIG. 3, shift control of a plurality of driving modes in the D range, shift control and belt clamping pressure control of the belt-type continuously variable transmission 24, engagement and release control of the lock-up clutch LU, and the like. This electronic control unit 80 is configured to include a so-called microcomputer having a CPU, ROM, RAM, input / output interface, etc., and performs signal processing according to a program stored in advance in the ROM while utilizing the temporary storage function of the RAM. The electronic control unit 80 is supplied with a signal representing the operation position Lpo, which is the operation position of the shift lever 88, from the operation position sensor 90. In addition, various information necessary for various controls, such as signals representing the turbine rotational speed Nt, the output rotational speed Nout corresponding to the vehicle speed V, and the accelerator operation amount Acc, which is the operation amount of the accelerator pedal, is supplied from the turbine rotational speed sensor 92, the output rotational speed sensor 94, the accelerator operation amount sensor 96, and the like. The accelerator operation amount Acc corresponds to the driver's driving force demand amount. The electronic control unit 80 corresponds to the control device of the vehicle power transmission device 10, but other controls such as the output control of the engine 12 may also be performed by the electronic control unit 80.

[0039] The mode switching control unit 82 shown in the electronic control device 80 of FIG. 1 switches between a plurality of driving modes in the D range, and executes mode switching control for switching between a gear driving mode that travels using the first power transmission path TP1 and a belt driving mode that travels using the second power transmission path TP2 during forward travel. For example, an upshift determination for switching from the gear driving mode to the belt driving mode and a downshift determination for switching from the belt driving mode to the gear driving mode are performed according to a shift map (shift condition) determined based on driving states such as the accelerator operation amount Acc and the vehicle speed V, and clutch-to-clutch shifting is executed to switch between the forward clutch C1 and the belt driving clutch C2 according to the shift determination. Specifically, mode switching is executed so that the vehicle travels in the gear driving mode at low vehicle speeds such as when starting the vehicle, and travels in the belt driving mode at a predetermined vehicle speed or higher. Further, in the belt driving mode, a belt low vehicle speed driving mode in which the synchronized engagement clutch S1 is engaged while the vehicle speed V is equal to or lower than a predetermined determination vehicle speed Vs, and a belt high vehicle speed driving mode in which the synchronized engagement clutch S1 is released when the vehicle speed exceeds the determination vehicle speed Vs are set.

[0040] In the gear driving mode, the belt low vehicle speed driving mode, and the belt high vehicle speed driving mode, when a predetermined lock-up condition is satisfied, the lock-up engagement hydraulic pressure Plu is regulated according to the output hydraulic pressure Pslu of the linear solenoid valve SLU, so that the lock-up clutch LU is fully engaged or slip engaged to achieve lock-up ON (LU-ON). Also, when the lock-up OFF (LU-OFF) occurs where the output of the hydraulic pressure Pslu from the linear solenoid valve SLU stops and the lock-up clutch LU is released, or during clutch-to-clutch shifting for switching between the gear driving mode and the belt driving mode, the circulation control hydraulic pressure Ptc is output from the ON-OFF solenoid valve SC3 under certain conditions, increasing the circulation flow rate of the hydraulic fluid in the torque converter 14.

[0041] The above-described mode switching control unit 82 also executes fail-safe control according to steps S1 to S7 of the flowchart in FIG. 5 when a predetermined abnormality is detected, such as when forward running cannot be appropriately performed. The flowchart in FIG. 5 is executed when the shift lever 88 is operated to the D position and the D range is selected.

[0042] In step S1, it is determined whether a predetermined abnormality has been detected, or in other words, whether a switching request to switch the CACV 116 to the second connection state and enter the retreat running mode has occurred. Specifically, for example, the presence or absence of an abnormality such as inability to run can be determined from the turbine rotation speed Nt, the vehicle speed V, the gear ratio γ2 of the belt-type continuously variable transmission 24, and the like. If there is no switching request, the process ends as it is. However, if a switching request has occurred, step S2 is executed to determine whether the ON-OFF solenoid valve SC3 is in the OFF state. If the ON-OFF solenoid valve SC3 is in the OFF state, step S4 is executed. However, when the ON-OFF solenoid valve SC3 is in the ON state, that is, when the circulation control hydraulic pressure Ptc is output to ensure the circulation flow rate of the hydraulic oil in the torque converter 14, an OFF command is output to the ON-OFF solenoid valve SC3 to stop the output of the circulation control hydraulic pressure Ptc, and the process waits in step S3 until the ON-OFF solenoid valve SC3 becomes in the OFF state. Whether the ON-OFF solenoid valve SC3 is in the OFF state can be determined by a command signal. However, since there is a response delay from the ON state to the OFF state until the circulation control hydraulic pressure Ptc decreases, it is desirable to confirm that it is in the OFF state by detecting the actual circulation control hydraulic pressure Ptc with, for example, a hydraulic pressure sensor or by measuring the circulation flow rate of the hydraulic oil in the torque converter 14. However, it may also be determined based on whether the elapsed time from the OFF command has reached a predetermined fixed time.

[0043] The reason for determining that the ON-OFF solenoid valve SC3 is in the OFF state in step S2 is that in the retreat travel mode, although the fail-switching hydraulic pressure Pfail is output from the linear solenoid valve SLU, this fail-switching hydraulic pressure Pfail is also output to the hydraulic pressure control side of the lock-up clutch LU via the SC3 switching valve 114. Therefore, if the circulation control hydraulic pressure Ptc is output from the ON-OFF solenoid valve SC3 to ensure the circulation flow rate of the hydraulic fluid in the torque converter 14, the hydraulic pressure in the torque converter 14 may become too high. For this reason, before the fail-switching hydraulic pressure Pfail is output from the linear solenoid valve SLU, the ON-OFF solenoid valve SC3 is turned OFF to stop the output of the circulation control hydraulic pressure Ptc.

[0044] FIG. 6 is an example of a time chart showing changes in the operating states of respective parts when a switching request for the CACV 116 occurs and fail-safe control is performed according to the flowchart of FIG. 5. FIG. 6 shows a case where a switching request for the CACV 116 occurs and the determination in step S1 becomes YES (affirmative) when the ON-OFF solenoid valve SC3 is in the ON state and the circulation control hydraulic pressure Ptc is being output. Time t1 is the time when an OFF command for turning the ON-OFF solenoid valve SC3 to the OFF state is output. Time t2 is the time when it is determined that the ON-OFF solenoid valve SC3 has become OFF, the determination in step S2 becomes YES, and the execution of step S4 and subsequent steps is started. The broken line in the column for the ON-OFF solenoid valve SC3 in FIG. 6 represents the actual hydraulic pressure change (response delay) of the circulation control hydraulic pressure Ptc. For the other columns in FIG. 6 as well, the solid line represents the command value and the broken line represents the actual hydraulic pressure change.

[0045] In step S4, the primary hydraulic pressure Ppri regulated by the linear solenoid valve SLP is increased by a predetermined pressure increase width α. In step S5, it is determined whether or not the pressure increase of the primary hydraulic pressure pri is completed. If the pressure increase is not completed, step S6 is executed and waiting is performed until the pressure increase is completed. If it is determined that the pressure increase is completed, step S7 is executed. Whether or not the pressure increase of the primary hydraulic pressure Ppri is completed can be determined by detecting the actual primary hydraulic pressure Ppri with, for example, a hydraulic pressure sensor or the like. However, it may also be determined based on whether or not the elapsed time from the pressure increase command (time t2 in FIG. 6) for the linear solenoid valve SLP has reached a predetermined fixed time. The time t2 in FIG. 6 is the time when a pressure increase command is output to the linear solenoid valve SLP in step S4 and the pressure increase of the primary hydraulic pressure Ppri is started in response to the increase in the output hydraulic pressure Pslp. The time t3 is the time when the determination of the completion of the pressure increase is made, and when the determination in step S5 becomes YES, step S7 is executed.

[0046] The reason for increasing the primary hydraulic pressure Ppri in step S4 is that when the fail switching hydraulic pressure Pfail is output from the linear solenoid valve SLU to enter the retreat travel mode and the CACV116 is switched to the second connection state (fail position) by the fail switching hydraulic pressure Pfail, the fail switching hydraulic pressure Pfail is supplied from the CACV116 to the PSCV120 and the primary hydraulic pressure Ppri is reduced. However, depending on the magnitude of the fail switching hydraulic pressure Pfail, there is a concern that belt slippage may occur. In order to prevent this belt slippage, the primary hydraulic pressure Ppri is increased by a predetermined pressure increase width α in advance by the linear solenoid valve SLP. In that case, if the timing of the pressure increase is too early, there is a risk that the belt-type continuously variable transmission 24 may upshift due to the pressure increase. Therefore, immediately before the fail switching hydraulic pressure Pfail is output from the linear solenoid valve SLU, that is, after confirming that the ON-OFF solenoid valve SC3 is in the OFF state, the primary hydraulic pressure Ppri is increased.

[0047] In step S7, failover hydraulic pressure Pfail is output from the linear solenoid valve SLU, and the ON-OFF solenoid valve SC1 is turned on to switch the SC1 switching valve 110 to the second connection state. As a result, as shown in FIG. 4, the failover hydraulic pressure Pfail output from the linear solenoid valve SLU is supplied to the CACV116 via the SC1 switching valve 110, and the CACV116 is switched to the second connection state (fail position) by the failover hydraulic pressure Pfail, and a failover travel mode is entered in which the belt travel clutch C2 is engaged based on the retreat travel hydraulic pressure Plimp.

[0048] The time t4 in FIG. 6 is the time when the CACV116 is switched to the second connection state (fail position) by the failover hydraulic pressure Pfail output from the linear solenoid valve SLU and the ON command of the ON-OFF solenoid valve SC1. At this time, the failover hydraulic pressure Pfail output from the linear solenoid valve SLU is supplied to the hydraulic pressure control side of the lock-up clutch LU via the SC3 switching valve 114. However, in steps S2 and S3, the ON-OFF solenoid valve SC3 is in the OFF state and the output of the circulation control hydraulic pressure Ptc is stopped, so there is no risk of the hydraulic pressure in the torque converter 14 becoming too high. Also, when the CACV116 is switched to the second connection state, the failover hydraulic pressure Pfail is supplied from the CACV116 to the PSCV120, and the primary hydraulic pressure Ppri of the belt-type continuously variable transmission 24 is reduced. However, since the primary hydraulic pressure Ppri was increased in steps S4 to S6, there is no risk of belt slip due to the reduction of the primary hydraulic pressure Ppri by the failover hydraulic pressure Pfail. The boost width α of the primary hydraulic pressure Ppri in step S4 is determined based on the failover hydraulic pressure Pfail so that the state in which the primary hydraulic pressure Ppri is reduced by the failover hydraulic pressure Pfail becomes the target value of the primary hydraulic pressure Ppri in the failover travel mode.

[0049] In such a vehicle power transmission device 10 of the present embodiment, the linear solenoid valve SLU for lock-up control not only executes the hydraulic control of the lock-up engagement hydraulic pressure Plu, but also outputs a fail-switching hydraulic pressure Pfail and is used for a fail-safe control to switch the CACV 116. Since it has a function of reducing the primary hydraulic pressure Ppri by the fail-switching hydraulic pressure Pfail, the number of parts can be reduced, and the hydraulic control circuit 70 can be configured at low cost and compactly.

[0050] On the other hand, when an abnormality is detected, after the ON-OFF solenoid valve SC3 for ensuring the circulation flow rate of the hydraulic fluid in the torque converter 14 is turned off to stop the output of the circulation control hydraulic pressure Ptc, the linear solenoid valve SLP increases the primary hydraulic pressure Ppri. After the increase in the primary hydraulic pressure Ppri is completed, the fail-switching hydraulic pressure Pfail is output from the linear solenoid valve SLU to switch the CACV 116 to the second connection state (fail position). Therefore, it is possible to prevent other hydraulic controls from being impaired by the influence of the fail-switching hydraulic pressure Pfail output from the linear solenoid valve SLU. That is, when the fail-switching hydraulic pressure Pfail is output from the linear solenoid valve SLU, the ON-OFF solenoid valve SC3 is surely in the output stop state, and there is no possibility of an increase in the flow rate to ensure the circulation flow rate. Therefore, it is possible to prevent the hydraulic pressure in the torque converter 14 from becoming too high when the fail-switching hydraulic pressure Pfail is supplied to the hydraulic control side of the lock-up clutch LU. Further, since the primary hydraulic pressure Ppri is increased by the linear solenoid valve SLP before the primary hydraulic pressure Ppri is reduced by the fail-switching hydraulic pressure Pfail, it is possible to prevent belt slippage from occurring due to the reduction of the primary hydraulic pressure Ppri by the fail-switching hydraulic pressure Pfail. In addition, since the increase in the primary hydraulic pressure Ppri by the linear solenoid valve SLP is immediately before the fail-switching hydraulic pressure Pfail is output from the linear solenoid valve SLU to switch the CACV 116 to the second connection state, it is possible to prevent the belt-type continuously variable transmission 24 from upshifting due to the increase in the primary hydraulic pressure Ppri.

[0051] As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, this is merely one embodiment, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art.

Explanation of Reference Numerals

[0052] 10: Vehicle power transmission device 14: Torque converter 16: Automatic transmission 22: Input shaft 24: Belt-type continuously variable transmission 28: Gear transmission mechanism (gear-type transmission) 30: Output shaft 60: Primary sheave 64: Secondary sheave 70: Hydraulic control circuit 80: Electronic control device (control device) 114: SC3 switching valve (lock-up / brake switching valve) 116: CACV (clutch apply control valve) LU: Lock-up clutch TP1: First power transmission path TP2: Second power transmission path C1: Forward clutch C2: Belt running clutch B1: Reverse brake S1: Synchronous engagement clutch SLU: Linear solenoid valve (lock-up hydraulic pressure control solenoid valve) SLP: Linear solenoid valve (primary hydraulic pressure control solenoid valve) SC1: ON-OFF solenoid valve SC2: ON-OFF solenoid valve SC3: ON-OFF solenoid valve (torque converter circulation control solenoid valve) Pfail: Fail switching hydraulic pressure Plimp: Retreat running hydraulic pressure Ptc: Circulation control hydraulic pressure Ppri: Primary hydraulic pressure PD: D-range pressure PR: R-range pressure

Claims

1. An automatic transmission having a torque converter with a lock-up clutch, a belt-type continuously variable transmission having a primary sheave and a secondary sheave, and a clutch for belt running, A clutch apply control valve that can be switched between a normal position and a fail position where the source pressure of a linear solenoid valve that regulates the working oil for the clutch for belt running is different, and is switched to the fail position by a fail switching hydraulic pressure, a lock-up hydraulic control solenoid valve that executes hydraulic control of the lock-up clutch, a torque converter circulation control solenoid valve that outputs a circulation control hydraulic pressure for ensuring the circulation flow rate of the working oil in the torque converter, and a primary hydraulic control solenoid valve that controls the primary hydraulic pressure supplied to the primary sheave according to the gear ratio, and a hydraulic control circuit having the same, A control device that, when a predetermined abnormality is detected, switches the clutch apply control valve to the fail position by the fail switching hydraulic pressure and sets a retreat running mode in which the vehicle runs using the clutch for belt running and the belt-type continuously variable transmission, In a vehicle power transmission device having the same, The fail switching hydraulic pressure is output from the lock-up hydraulic control solenoid valve, The hydraulic control circuit is configured such that when the clutch apply control valve is switched to the fail position, the primary hydraulic pressure is reduced by the output of the fail switching hydraulic pressure from the clutch apply control valve, When the control device detects the abnormality, it determines whether or not the torque converter circulation control solenoid valve is in an output stop state in which the output of the circulation control hydraulic pressure is stopped, and after determining that it is in the output stop state, it increases the primary hydraulic pressure by the primary hydraulic control solenoid valve and determines whether or not the increase in the primary hydraulic pressure is completed. After determining that the increase in the primary hydraulic pressure is completed, it outputs the fail switching hydraulic pressure from the lock-up hydraulic control solenoid valve to switch the clutch apply control valve to the fail position A vehicle power transmission device characterized by the above.

2. The automatic transmission has a first power transmission path and a second power transmission path provided in parallel between an input shaft and an output shaft to which power is transmitted from the torque converter. The first power transmission path is provided with a gear type transmission device, a forward clutch, a reverse brake, and a synchronized engagement clutch so that forward and reverse driving are possible. On the other hand, the second power transmission path is provided with the belt type continuously variable transmission and the belt running clutch so that forward driving is possible. The vehicle power transmission device according to claim 1, characterized in that.

3. The hydraulic control circuit is switchable between a state in which a D range pressure serving as the source pressure of the engagement hydraulic pressure of the forward clutch and the belt running clutch is output and a state in which an R range pressure serving as the source pressure of the engagement hydraulic pressure of the reverse brake is output. In the state in which the R range pressure is output, an ON-OFF solenoid valve SC1 that allows the fail switching hydraulic pressure output from the lock-up hydraulic pressure control solenoid valve to be supplied to the clutch apply control valve; an ON-OFF solenoid valve SC2 that switches the supply state of the hydraulic pressure to the synchronized engagement clutch; has a lock-up control position where the hydraulic pressure output from the lock-up hydraulic pressure control solenoid valve is used for the hydraulic pressure control of the lock-up clutch and a brake control position where the hydraulic pressure output from the lock-up hydraulic pressure control solenoid valve is used for the hydraulic pressure control of the reverse brake. A lock-up / brake switching valve that allows the lock-up hydraulic pressure control solenoid valve to be used for the hydraulic pressure control of the reverse brake in addition to the hydraulic pressure control of the lock-up clutch; an ON-OFF solenoid valve SC3 that switches the lock-up / brake switching valve between the lock-up control position and the brake control position and also serves as the torque converter circulation control solenoid valve; It is provided, and in a state where the clutch apply control valve is held at the normal position, the D-range pressure is output as the source pressure of the linear solenoid valve that regulates the working oil for the belt running clutch from the clutch apply control valve. When switched to the fail position, the hydraulic pressure for retreat running supplied to the clutch apply control valve through a path different from the D-range pressure is output as the source pressure of the linear solenoid valve that regulates the working oil for the belt running clutch. After determining that the boosting of the primary hydraulic pressure by the primary hydraulic pressure control solenoid valve is completed, the control device outputs the fail-switching hydraulic pressure from the lock-up hydraulic pressure control solenoid valve, and switches the ON-OFF solenoid valve SC1 to a state where the R-range pressure is output, thereby switching the clutch apply control valve to the fail position. The vehicle power transmission device according to claim 2, characterized by the above.

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