JP5772663B2 - Control device for continuously variable transmission - Google Patents

Description

  The present invention relates to a control device for a continuously variable transmission.

  Generally, a continuously variable transmission (hereinafter also referred to as CVT: Continuously Variable Transmission) is known as an automatic transmission mounted on a vehicle. The CVT is a primary pulley driven by power generated in the engine, an output-side secondary pulley connected to drive wheels, and a power transmission element (hereinafter referred to as a belt or chain) wound around the primary pulley and the secondary pulley. A belt).

  Each of the primary pulley and the secondary pulley includes a fixed sheave and a movable sheave. A V-groove is formed between the fixed sheave and the movable sheave. The movable sheave has a hydraulic cylinder to which oil is supplied on the back side, and is moved in the axial direction by the hydraulic pressure in the hydraulic cylinder. CVT adjusts the space | interval of a fixed sheave and a movable sheave by moving a movable sheave in an axial direction, and changes the groove width of a primary pulley and a secondary pulley.

  The control device for the continuously variable transmission supplies primary sheave pressure oil to the hydraulic cylinder of the primary pulley and also supplies belt clamping pressure oil to the hydraulic cylinder of the secondary pulley. The control device of the continuously variable transmission changes the effective winding diameter of the belt with respect to the primary pulley and the secondary pulley by changing the groove widths of the primary pulley and the secondary pulley, thereby changing the transmission ratio of the CVT steplessly. It has become.

  By the way, in this type of continuously variable transmission control device, a technique for supplying belt clamping pressure to the hydraulic cylinder of the primary pulley when a failure occurs in the valve for regulating the primary sheave pressure has been developed. (For example, refer to Patent Document 1). This continuously variable transmission control device suppresses the occurrence of some failure in the valve for regulating the primary sheave pressure, which causes a sudden change in the CVT gear ratio and instability of the running state of the vehicle. The evacuation traveling can be ensured.

  Here, in a vehicle equipped with a CVT, it is desirable that the gear ratio of the CVT is the maximum gear ratio, that is, the lowest, in order to start smoothly and smoothly when starting.

JP 2009-270690 A

  However, in the control device of the conventional continuously variable transmission, the retreat travel is ensured when a failure occurs in the valve that supplies the primary sheave pressure, but the CVT gear ratio is set to the lowest level when the vehicle stops. Setting was not considered. For this reason, in a vehicle equipped with a conventional continuously variable transmission control device, there is a possibility that the CVT gear ratio may not be at the lowest level when the vehicle restarts after retreating and stopping. .

  The present invention has been made to solve such a problem. In a vehicle equipped with a CVT, when the primary sheave pressure supply system fails during retreat and stops, the CVT shift at the next start is performed. It is an object of the present invention to provide a control device for a continuously variable transmission that can make the ratio the lowest.

In order to achieve the above object, the continuously variable transmission control device according to the present invention includes (1) an input shaft to which rotational power is transmitted from a drive shaft of a vehicle drive source, and an output for transmitting the rotational power to drive wheels. A starting clutch that switches a transmission state between a shaft, an engaged state that engages between the input shaft and the output shaft, and a released state that releases between the input shaft and the output shaft; and the input shaft A driving pulley connected to the output shaft, a driven pulley connected to the output shaft, and a belt wound around the driving pulley and the driven pulley, the driving pulley and the driven pulley. By supplying hydraulic oil to at least one of the driving pulleys, the belt clamping pressure from the driving pulley and the driven pulley to the belt is changed, and the driving pulley and the driven pulley Yes A continuously variable transmission that continuously controls the gear ratio by changing the winding diameter, primary sheave pressure supply means that generates primary sheave pressure, and secondary sheave pressure that supplies secondary sheave pressure to the driven pulley Switchable between at least two states: a supply means, a normal state in which the primary sheave pressure is supplied to the driving pulley, and a fail state in which the secondary sheave pressure is supplied to the driving pulley and the driven pulley A hydraulic control circuit having a sheave pressure switching valve and a starting clutch pressure regulating valve that regulates a starting clutch pressure supplied to the starting clutch, and when the vehicle is stopped, the starting clutch pressure is set to a predetermined value. Garage control that controls the starting clutch from the disengaged state to the engaged state by controlling with a hydraulic gradient. A control device for a continuously variable transmission, wherein when the primary sheave pressure supply means fails, the sheave pressure switching valve is switched to the fail state, and the start clutch pressure is controlled to control the start clutch When the vehicle speed drops to a speed at which the start clutch can be engaged, the start clutch pressure is controlled to switch the start clutch to the engaged state, and then the sheave pressure switching valve is turned on. The shift ratio is shifted to the maximum shift ratio by switching to the normal state, and the hydraulic pressure gradient of the starting clutch pressure when the starting clutch is switched to the engaged state is larger than the predetermined hydraulic pressure gradient in the garage control. Configure as high.

  In the present specification, the belt means an endless transmission member including a chain in addition to a so-called belt such as a V belt or a flat belt. In this specification, the release state of the starting clutch includes not only complete release but also a state in which power is transmitted with slipping, such as half-engagement.

  Here, when the primary sheave pressure supply means fails, the control device for the continuously variable transmission switches the sheave pressure switching valve to the fail state, and controls the start clutch pressure to switch the start clutch to the released state. A person cannot accelerate the vehicle by operating the accelerator pedal. As a result, the control device for the continuously variable transmission at this time is subjected to a limitation that acceleration cannot be performed during the retreat travel of the vehicle. Therefore, the conventional continuously variable transmission control device cannot be accelerated until the sheave pressure switching valve is switched to the normal state again. Further, the control device for the continuously variable transmission may not be able to shift the gear ratio to the lowest level until the vehicle stops even if the hydraulic pressure is supplied to the starting clutch with a hydraulic pressure gradient similar to that of the garage control.

  According to the configuration of the present invention, the control device for the continuously variable transmission controls the start clutch pressure and switches the start clutch to the engaged state when the vehicle speed decreases to a speed at which the start clutch can be engaged. The power from the drive source can be used at an early stage. Thereby, the restriction | limiting of the evacuation driving | running | working of a vehicle is reduced conventionally.

  Further, the control device for the continuously variable transmission has the hydraulic pressure gradient of the starting clutch pressure when the starting clutch is switched to the engaged state higher than the predetermined hydraulic pressure gradient in the garage control, so that the starting clutch is quickly brought into the engaged state. Can be switched. For this reason, since the timing for switching the sheave pressure switching valve from the fail state to the normal state can be made earlier, it is possible to secure a long time for the speed ratio of the continuously variable transmission to become the lowest, and thus the speed ratio can be increased. It is possible to achieve the lowest level more reliably.

  In addition, since the control device for the continuously variable transmission can secure a long time for the gear ratio of the continuously variable transmission to become the lowest, it is possible to improve the accuracy for setting the gear ratio to the lowest. Therefore, when the primary sheave pressure supply means fails and the vehicle stops, the control device for the continuously variable transmission can set the transmission ratio of the continuously variable transmission to the lowest level at the next start.

  In the control device for a continuously variable transmission described in (1) above, (2) the sheave pressure switching valve allows the hydraulic oil to flow from the starting clutch pressure regulating valve to the starting clutch in the fail state. Configure to

  With this configuration, the continuously variable transmission control device can control whether or not the starting clutch pressure is supplied from the starting clutch pressure regulating valve to the starting clutch by the sheave pressure switching valve, so that the number of parts does not increase. Control with the control device of the continuously variable transmission can be simplified.

  According to the present invention, in a vehicle equipped with a CVT, when the primary sheave pressure supply system fails during retreat and stops, the control of the continuously variable transmission that can make the CVT gear ratio at the next start the lowest. An apparatus can be provided.

It is the schematic which shows the vehicle carrying the control apparatus of the continuously variable transmission which concerns on embodiment of this invention. 1 is a schematic skeleton diagram showing a transmission equipped with a continuously variable transmission control device according to an embodiment of the present invention. It is a block diagram which shows schematic structure of the hydraulic control apparatus which concerns on embodiment of this invention. It is a circuit diagram which shows schematic structure of the sheave pressure control part and forward clutch control part which concern on embodiment of this invention. It is a flowchart which shows operation | movement of the control apparatus of the continuously variable transmission which concerns on embodiment of this invention. It is a time chart which shows operation | movement of the control apparatus of the continuously variable transmission which concerns on embodiment of this invention. It is a flowchart which shows operation | movement of the control apparatus of the continuously variable transmission which concerns on other embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, the configuration will be described.

  As shown in FIG. 1, the vehicle 10 according to the present embodiment includes an engine 11 as a drive source, a transmission 20, a hydraulic control device 30, a differential mechanism 40, a drive shaft 43, and drive wheels 45. ECU (Electronic Control Unit) 100. In the present embodiment, the control device for the continuously variable transmission includes the ECU 100 and controls the transmission 20 including the continuously variable transmission 70 described later.

  The engine 11 is composed of a power device that is a known internal combustion engine that outputs power by burning a mixture of hydrocarbon fuel such as gasoline or light oil and air in a combustion chamber of a cylinder (not shown). . The engine 11 is configured to reciprocate the piston in the cylinder by intermittently repeating intake, combustion, and exhaust of the air-fuel mixture in the combustion chamber, and rotate the crankshaft 15 connected to the piston. The fuel used for the engine 11 is not limited to gasoline or light oil, but may be an alcohol fuel containing alcohol such as ethanol. The crankshaft 15 is connected to the transmission 20 and transmits power generated by the engine 11 to the transmission 20.

  The hydraulic control device 30 supplies the oil as hydraulic oil to the transmission 20 and controls the transmission 20 by adjusting the hydraulic pressure of the supplied oil. The hydraulic control device 30 switches hydraulic circuits and controls hydraulic pressure by a plurality of solenoid valves and the like controlled by the ECU 100.

  The drive shaft 43 has a left drive shaft 43L and a right drive shaft 43R. The drive wheel 45 has a left drive wheel 45L and a right drive wheel 45R. The differential mechanism 40 transmits the power transmitted from the transmission 20 to the left drive wheel 45L by rotating the left drive shaft 43L, and transmits the power to the right drive wheel 45R by rotating the right drive shaft 43R. It has become. Thus, the differential mechanism 40 absorbs the difference in the rotational speed between the left drive wheel 45L and the right drive wheel 45R when traveling on a curve or the like.

  The drive wheel 45 includes a metal wheel attached to the drive shaft 43 and a resin tire attached to the outer periphery of the wheel. The drive wheel 45 is rotated by the power transmitted by the drive shaft 43 and causes the vehicle 10 to travel by the frictional action between the tire and the road surface.

  The ECU 100 includes a central processing unit (CPU) as a central processing unit, a read only memory (ROM) that stores fixed data, a random access memory (RAM) that temporarily stores data, and an input interface. An output interface (none of which is shown), an EEPROM (Electrically Erasable and Programmable Read Only Memory) composed of a rewritable nonvolatile memory, and a communication means. The ECU 100 is a vehicle electronic control device that supervises overall control of the vehicle 10.

  For example, the ROM stores a continuously variable transmission control program according to the present embodiment, a map, and the like, and functions as a storage device. The CPU executes arithmetic processing based on the control program and map stored in the ROM. In the present embodiment, the continuously variable transmission control program is executed at predetermined time intervals (for example, 10 ms) by the ECU 100.

  The map stored in the ROM includes a primary sheave pressure Pin of an input side hydraulic cylinder 73 of a primary pulley 72 described later, a belt clamping pressure Pd of an output side hydraulic cylinder 78 of a secondary pulley 77, and a shift of the continuously variable transmission 70. There is a map showing the relationship between the ratio γ and the estimated input torque Tin to the continuously variable transmission 70. Further, as a map stored in the ROM, there is a map representing an optimum fuel consumption line for obtaining a required torque and a required engine speed at which the target engine output can be achieved with the optimum fuel consumption.

In the ROM, the gradient of the forward clutch pressure Pc when the forward clutch 64 is switched to the engaged state in the garage control is stored as a predetermined hydraulic pressure gradient. Further, the ROM, regardless of the γ gear ratio in the fail state during running, engageable upper speed forward clutch 64 straight pressure is preset and stored as the predetermined speed V _1. Further, the ROM, the lower limit speed at which the gear ratio of CVT70 gamma is the outermost Low before stop has been previously set and stored as the predetermined speed V _2. Further, the ROM, the lower limit vehicle speed reliably speed ratio γ until stopped by the sheave pressure switching valve 660 to the normal state can be the outermost Low has been previously set and stored as the lower limit vehicle speed V _3.

  The RAM temporarily stores calculation results by the CPU, data input from various sensors described later, and the like. Further, for example, data that should be saved when the engine 11 is stopped is stored by an EEPROM, a backup memory, or the like that is configured by a non-volatile memory.

  The CPU, RAM, ROM, input interface, and output interface are connected to each other via a bus. Various sensors are connected to the input interface, and signals detected by these sensors are input. For example, a solenoid valve or the like constituting the hydraulic control circuit 31 (see FIG. 3) is connected to the output interface. The ECU 100 inputs signals from various sensors from the input interface, performs calculations by the CPU with reference to the RAM and ROM as necessary, and outputs from the output interface, thereby executing various controls according to the present embodiment. It is supposed to be.

  The vehicle 10 includes a crank sensor 81, a shift sensor 82, a drive shaft rotational speed sensor 83, and an accelerator opening sensor 84.

  The crank sensor 81 is configured by a crank position sensor that can detect the engine rotational speed by detecting the crank position and the crank angle of the crankshaft 15. The crank sensor 81 detects the rotation speed of the crankshaft 15 and converts it into a signal, and inputs the signal to the ECU 100. The ECU 100 acquires the rotational speed of the crankshaft 15 represented by the detection signal input by the crank sensor 81 as the engine rotational speed Ne.

  The shift sensor 82 has a shift lever 21 in which of the various shift positions such as parking (P), reverse (R), neutral (N), drive (D), low (L), manual (M), etc. It is comprised by the shift position sensor which detects whether it exists in. The shift sensor 82 detects the shift position of the shift lever 21 and converts it into a signal, and inputs the signal to the ECU 100.

  The drive shaft rotational speed sensor 83 detects the rotational speed of the left drive shaft 43L, converts it into a signal, and inputs the signal to the ECU 100. The ECU 100 calculates the traveling speed of the vehicle 10 based on a detection signal representing the rotation speed of the left drive shaft 43L input by the drive shaft rotation speed sensor 83. In the present embodiment, the drive shaft rotational speed sensor 83 detects the rotational speed of the left drive shaft 43L, but is not limited thereto, and may detect the rotational speed of the right drive shaft 43R. Good.

  The accelerator opening sensor 84 is disposed in the vicinity of the accelerator pedal 19 operated by the driver's stepping, and detects the opening of the accelerator pedal 19 (hereinafter also referred to as accelerator opening Acc). The accelerator opening sensor 84 is a linear accelerator position sensor that can obtain an output voltage that is linearly related to the amount of depression of the accelerator pedal 19. The accelerator opening sensor 84 detects the accelerator opening Acc, converts it into a signal, and inputs the signal to the ECU 100. The ECU 100 acquires the accelerator opening Acc represented by the detection signal input by the accelerator opening sensor 84 as an output of the engine 11.

  Next, the configuration of the transmission 20 will be described with reference to FIG.

  The transmission 20 includes a torque converter 50 as a fluid transmission mechanism, a CVT 70, and a reduction gear mechanism 80. The power output from the engine 11 is transmitted to the differential mechanism 40 through a power transmission path of torque converter 50 → CVT 70 → reduction gear mechanism 80, and distributed to the left drive wheel 45L and the right drive wheel 45R. Yes.

  The torque converter 50 includes a pump impeller 51p, a turbine runner 51t, a stator 51s, a front cover 52, and a lockup clutch 53. Torque converter 50 is provided between engine 11 and CVT 70.

  The pump impeller 51p is connected to the crankshaft 15 via the front cover 52. The turbine runner 51 t is connected to the forward / reverse switching machine 60 via the turbine shaft 54. The stator 51s is rotatably supported by a non-rotating member via a one-way clutch.

  The pump impeller 51p and the turbine runner 51t are provided to face each other. Opposite portions of the pump impeller 51p and the turbine runner 51t are each provided with a large number of blades and filled with oil. As a result, power is transmitted between the pump impeller 51p and the turbine runner 51t via oil.

  A lockup clutch 53 is provided on the turbine runner 51t. The lockup clutch 53 is attached so as to rotate integrally with the turbine shaft 54 and is configured to be movable in the axial direction of the turbine shaft 54. A release side oil chamber 55 is formed between the lockup clutch 53 and the front cover 52. A release side oil passage 56 communicates with the release side oil chamber 55. An engagement side oil chamber 57 is formed between the lockup clutch 53 and the turbine runner 51t. An engagement side oil passage 58 and a drain oil passage 59 communicate with the engagement side oil chamber 57.

  The lockup clutch 53 moves in the axial direction by a lockup differential pressure ΔP (= Pon−Poff) between the engagement side hydraulic pressure Pon in the engagement side oil chamber 57 and the release side hydraulic pressure Poff in the release side oil chamber 55. Thus, the front cover 52 is switched between an engaged state and a released state. The lock-up clutch 53 is designed to improve fuel efficiency by integrally connecting the pump impeller 51p and the turbine runner 51t and rotating them together.

  The CVT 70 includes an input shaft 70a, a forward / reverse switching device 60, a primary pulley 72 as a driving pulley, a secondary pulley 77 as a driven pulley, a belt 75, and a secondary shaft 79 as an output shaft. Have.

  The forward / reverse switching machine 60 is constituted by a double pinion type planetary gear device. The forward / reverse switching machine 60 includes a sun gear 61, a carrier 62, a ring gear 63, a forward clutch 64 as a start clutch, and a reverse brake 66.

  The input shaft 70 a is coaxially connected to the turbine shaft 54 of the torque converter 50. The sun gear 61 rotates with the input shaft 70a as a rotation axis. The carrier 62 is rotatably connected to the respective rotation shafts of a first pinion gear 67 and a second pinion gear 68 provided between the sun gear 61 and the ring gear 63 and is also connected to a primary shaft 71 of the CVT 70.

  The forward clutch 64 is provided between the carrier 62 and the sun gear 61. The forward clutch 64 switches a transmission state between an engaged state in which the input shaft 70a and the secondary shaft 79 are engaged and a released state in which the input shaft 70a and the secondary shaft 79 are released. ing. The reverse brake 66 is provided between the ring gear 63 and the housing 65, and is switched between an engaged state and a released state by hydraulic pressure.

  In the forward / reverse switching machine 60, when the forward clutch 64 is engaged and the reverse brake 66 is released, the sun gear 61, the carrier 62, and the ring gear 63 are rotated together, and the turbine shaft 54 is moved to the primary shaft. 71 is directly connected. Thereby, the driving force in the forward direction is transmitted from the turbine shaft 54 to the primary shaft 71, and finally transmitted to the drive wheels 45.

  In the forward / reverse switching machine 60, the ring gear 63 is fixed when the forward clutch 64 is disengaged and the reverse brake 66 is engaged. For this reason, the carrier 62 rotates in the opposite direction via the first pinion gear 67 and the second pinion gear 68 with respect to the rotation direction of the sun gear 61 that rotates integrally with the turbine shaft 54. Therefore, since the primary shaft 71 connected to the carrier 62 is rotated in the reverse direction with respect to the turbine shaft 54, the reverse driving force is transmitted to the driving wheel 45.

  The belt 75 is wound around V grooves formed in the primary pulley 72 and the secondary pulley 77, respectively. The CVT 70 transmits power by using a frictional force between the inner wall portion of the V groove of the primary pulley 72 and the secondary pulley 77 and the belt 75.

  In this embodiment, as means for controlling the clamping force to the belt 75 from the primary pulley 72 and the secondary pulley 77, the oil pressure of the oil supplied to the pulleys 72 and 77 is controlled.

  The primary pulley 72 includes a movable sheave 72 a, a fixed sheave 72 b, and an input side hydraulic cylinder 73. The movable sheave 72a is provided so as to be rotatable integrally with the primary shaft 71 and movable in the axial direction. The fixed sheave 72b is provided so that it can rotate integrally with the primary shaft 71 and cannot move in the axial direction. The input side hydraulic cylinder 73 moves the movable sheave 72a in the axial direction by the primary sheave pressure Pin.

  The primary pulley 72 can change the V groove width between the primary pulley 72 and the fixed sheave 72 b by moving the movable sheave 72 a in the axial direction by the input side hydraulic cylinder 73. The primary pulley 72 changes the effective diameter, that is, the effective winding diameter of the belt 75 by changing the V groove width.

  The secondary pulley 77 includes a movable sheave 77 a, a fixed sheave 77 b, and an output side hydraulic cylinder 78. The movable sheave 77a is provided so as to be rotatable integrally with the secondary shaft 79 and movable in the axial direction. The fixed sheave 77b is provided so that it can rotate integrally with the secondary shaft 79 and cannot move in the axial direction. The output-side hydraulic cylinder 78 moves the movable sheave 77a in the axial direction by the belt clamping pressure Pd.

  The secondary pulley 77 can change the width of the V groove between the secondary pulley 77 and the fixed sheave 77 b by moving the movable sheave 77 a in the axial direction by the output-side hydraulic cylinder 78. The secondary pulley 77 changes the effective diameter, that is, the effective winding diameter of the belt 75 by changing the V groove width.

  The V groove widths of the primary pulley 72 and the secondary pulley 77 are changed by the hydraulic pressure of the oil supplied from the hydraulic control device 30 to the input side hydraulic cylinder 73 and the output side hydraulic cylinder 78, and the effective winding diameter of the belt 75 is changed. Has been changed. The CVT 70 can change the gear ratio steplessly by controlling the thrust applied in the axial direction of the primary pulley 72 and the secondary pulley 77.

  In the CVT 70 of the present embodiment, the primary sheave pressure Pin of the input side hydraulic cylinder 73 is controlled by the hydraulic control circuit 31, so that the V groove width of the primary pulley 72 changes and the effective winding diameter of the belt 75 changes. Is done. Thereby, ECU 100 can continuously change the transmission gear ratio γ of CVT 70 (= the rotational speed Nin of primary shaft 71 / the rotational speed Nout of secondary shaft 79).

  Further, in the CVT 70 of the present embodiment, the belt clamping pressure Pd of the output side hydraulic cylinder 78 is controlled by the hydraulic control circuit 31, so that the belt clamping pressure from the secondary pulley 77 is prevented from causing the belt 75 to slip. Be controlled.

  The CVT 70 can switch the shift range according to the driver's request. The CVT 70 includes a P (parking) range, an N (neutral) range, a D (drive) range, an R (reverse) range, an M (manual) range (sequential shift range), and the like as shift ranges.

  The transmission 20 includes an input shaft rotational speed sensor 85, an output shaft rotational speed sensor 86, and a turbine torque sensor 87. The input shaft rotational speed sensor 85 detects the rotational speed Nin of the primary shaft 71, converts it into a signal, and inputs the signal to the ECU 100. The output shaft rotational speed sensor 86 detects the rotational speed Nout of the secondary shaft 79, converts it into a signal, and inputs the signal to the ECU 100. The turbine torque sensor 87 detects the torque of the turbine shaft 54, converts it into a signal, and inputs the signal to the ECU 100.

  Next, the configuration of the hydraulic control circuit 31 included in the hydraulic control device 30 will be described with reference to FIG.

  As shown in FIG. 3, the hydraulic control circuit 31 includes an oil supply unit 200, a line pressure regulating unit 300, a lockup clutch control unit 400, a forward clutch control unit 500, and a sheave pressure control unit 600. ing. These are all controlled by the ECU 100.

  The oil supply unit 200 supplies oil by an oil pump (not shown). The line pressure adjusting unit 300 adjusts the oil pressure of the oil supplied from the oil supply unit 200 to the line pressure PL. The line pressure adjusting unit 300 supplies the secondary pressure Psec and the signal pressure Pslu to the lockup clutch control unit 400 and also supplies the signal pressure Pslu to the forward clutch control unit 500.

  The lockup clutch control unit 400 supplies the lockup differential pressure ΔP to the lockup clutch 53 in accordance with the secondary pressure Psec and the signal pressure Pslu from the line pressure regulating unit 300.

  As shown in FIG. 4, the forward clutch control unit 500 includes a garage switching valve 510 and a starting clutch pressure regulating valve 520. The garage switching valve 510 includes a sheave pressure switching valve 660 described later. The garage switching valve 510 has an input port 511, an input port 512, and an output port 513. The input port 511 is in communication with the line pressure adjusting unit 300. The input port 512 is in communication with the starting clutch pressure regulating valve 520. The output port 513 is in communication with the forward clutch 64.

  The garage switching valve 510 can be switched between a normal state in which the input port 511 communicates with the output port 513 and a fail state in which the input port 512 communicates with the output port 513 by an axial movement of a spool valve (not shown). . Therefore, the forward clutch 64 is controlled by the signal pressure Pslu supplied from the line pressure regulator 300 when the garage switching valve 510 is in the normal state. Further, the forward clutch 64 is controlled by the control pressure P4 supplied from the starting clutch pressure regulating valve 520 when the garage switching valve 510 is in a fail state. Therefore, the forward clutch control unit 500 applies the forward clutch pressure Pc as the starting clutch pressure to the forward clutch 64 in accordance with the signal pressure Pslu from the line pressure regulating unit 300 or the control pressure P4 from the starting clutch pressure regulating valve 520. It comes to supply.

  The starting clutch pressure regulating valve 520 is composed of a linear solenoid valve, for example, and is supplied with oil through an oil passage (not shown). The starting clutch pressure regulating valve 520 regulates the hydraulic pressure of the supplied oil to the control pressure P4 and supplies it to the input port 512 of the garage switching valve 510.

  The sheave pressure control unit 600 includes a line pressure modulator valve 610, a primary sheave pressure regulating valve 620, a transmission solenoid valve 630, a secondary sheave pressure regulating valve 640, a belt clamping solenoid valve 650, and a sheave pressure switching valve 660. And an on-off solenoid valve 670. The primary sheave pressure regulating valve 620 and the secondary sheave pressure regulating valve 640 supply the sheave pressure to at least one of the primary pulley 72 and the secondary pulley 77 to change the belt clamping pressure.

  Further, the primary sheave pressure regulating valve 620 and the shift solenoid valve 630 constitute primary sheave pressure supply means of the present invention. Further, secondary sheave pressure regulating valve 640 and belt clamping pressure solenoid valve 650 constitute secondary sheave pressure supply means of the present invention. Primary sheave pressure regulating valve 620 and transmission solenoid valve 630 generate primary sheave pressure. The secondary sheave pressure regulating valve 640 and the belt clamping solenoid valve 650 are configured to supply the secondary sheave pressure, that is, the belt clamping pressure Pd, to the secondary pulley 77. When at least one of the primary sheave pressure regulating valve 620 and the shift solenoid valve 630 fails, a downshift failure occurs in the CVT 70.

  The line pressure modulator valve 610 has an input port 611 and an output port 612. The input port 611 is in communication with the oil supply unit 200. The line pressure PL adjusted by the line pressure adjusting unit 300 is supplied to the line pressure modulator valve 610 and adjusted by the line pressure modulator valve 610 according to an instruction from the ECU 100.

  The primary sheave pressure regulating valve 620 is a normally open type signal operating valve, and has an input port 621, an output port 622, and a signal pressure port 623. The input port 621 is in communication with the output port 612 of the line pressure modulator valve 610. The signal pressure port 623 is in communication with the transmission solenoid valve 630. The primary sheave pressure regulating valve 620 regulates the oil that has flowed into the input port 621 from the line pressure modulator valve 610 in accordance with the signal pressure P 1 from the transmission solenoid valve 630 and flows out from the output port 622.

  The ECU 100 calculates the primary sheave pressure Pin of the input side hydraulic cylinder 73 of the primary pulley 72 based on a map showing the relationship among the belt clamping pressure Pd, the gear ratio γ, the accelerator opening Acc, and the primary sheave pressure Pin. It is supposed to be.

  The primary sheave pressure regulating valve 620 fully opens the input port 621 and supplies the oil pressure flowing out from the output port 622 to the oil flowing into the input port 621 when the oil is not supplied from the speed change solenoid valve 630. It is made constant according to the hydraulic pressure.

  On the other hand, the primary sheave pressure regulating valve 620 closes the input port 621 with an appropriate opening degree by the movement of a spool valve (not shown) when the signal pressure P4 is supplied from the transmission solenoid valve 630. The primary sheave pressure regulating valve 620 changes the primary sheave pressure Pin of oil flowing out from the output port 622 according to the opening degree of the input port 621.

  The shift solenoid valve 630 regulates oil supplied through an oil passage (not shown) and outputs it as a signal pressure P1. The shift solenoid valve 630 is composed of, for example, a duty solenoid valve, and the signal pressure P1 of oil supplied to the signal pressure port 623 is controlled by applying an electric current from the ECU 100. The ECU 100 adjusts the primary sheave pressure Pin output from the primary sheave pressure regulating valve 620 by controlling the signal pressure P1 supplied from the transmission solenoid valve 630 to the primary sheave pressure regulating valve 620.

  The secondary sheave pressure regulating valve 640 is a normally open type signal operating valve, and has an input port 641, an output port 642, and a signal pressure port 643. The input port 641 is in communication with the output port 612 of the line pressure modulator valve 610. The output port 642 is in communication with the output side hydraulic cylinder 78 of the secondary pulley 77. The signal pressure port 643 is communicated with the belt clamping solenoid valve 650. The secondary sheave pressure regulating valve 640 regulates the oil flowing into the input port 641 from the line pressure modulator valve 610 according to the signal pressure P2 from the belt clamping solenoid valve 650, and flows out from the output port 642.

  The secondary sheave pressure regulating valve 640 fully opens the input port 641 and flows the oil pressure of the oil flowing out from the output port 642 from the input port 641 in an off state where no oil is supplied from the belt clamping solenoid valve 650. It is designed to be constant according to the oil pressure.

  On the other hand, when the signal pressure P2 is supplied from the belt clamping solenoid valve 650, the secondary sheave pressure regulating valve 640 closes the input port 641 with an appropriate opening degree by movement of a spool valve (not shown). Yes. The secondary sheave pressure regulating valve 640 changes the belt clamping pressure Pd of the oil flowing out from the output port 642 according to the opening degree of the input port 641.

  The belt clamping solenoid valve 650 regulates oil supplied through an oil passage (not shown) and outputs it as a signal pressure P2. The belt clamping solenoid valve 650 is composed of, for example, a linear solenoid valve, and the signal pressure P2 of the oil supplied to the signal pressure port 643 is controlled by applying an electric current from the ECU 100. The ECU 100 adjusts the belt clamping pressure Pd output from the secondary sheave pressure regulating valve 640 by controlling the signal pressure P2 supplied from the belt clamping solenoid valve 650 to the secondary sheave pressure regulating valve 640. .

  The sheave pressure switching valve 660 functions as a relay device that causes the oil that has flowed out from the primary sheave pressure regulating valve 620 and the oil that has flowed out from the secondary sheave pressure regulating valve 640 to flow into the primary pulley 72. The sheave pressure switching valve 660 switches between the oil supplied from the primary sheave pressure regulating valve 620 and the oil supplied from the secondary sheave pressure regulating valve 640 and supplies it to the primary pulley 72. .

  The sheave pressure switching valve 660 has an input port 661 of the primary sheave pressure regulating valve 620, an input port 662 of the secondary sheave pressure regulating valve 640, an output port 663, and a signal pressure port 664. The input port 661 is in communication with the output port 622 of the primary sheave pressure regulating valve 620. The input port 662 is in communication with the output port 642 of the secondary sheave pressure regulating valve 640. The output port 663 communicates with the input side hydraulic cylinder 73 of the primary pulley 72. The signal pressure port 664 is in communication with the on / off solenoid valve 670.

  One of the input port 661 and the input port 662 communicates with the output port 663 so as to be switchable. The sheave pressure switching valve 660 can be switched between a normal state in which the input port 661 communicates with the output port 663 and a fail state in which the input port 662 communicates with the output port 663 by an axial movement of a spool valve (not shown). Yes. That is, the sheave pressure switching valve 660 can be switched between at least one of a normal state in which the primary sheave pressure Pin is supplied to the primary pulley 72 and a fail state in which the belt clamping pressure Pd is supplied to the secondary pulley. Yes.

  Here, the sheave pressure switching valve 660 and the garage switching valve 510 are the same switching valve. For this reason, when the sheave pressure switching valve 660 is switched to the normal state, the garage switching valve 510 is also in the normal state, and when the sheave pressure switching valve 660 is switched to the fail state, the garage switching valve 510 is also switched. Moreover, it becomes a failure state.

  When the sheave pressure switching valve 660 is set in the normal state, the ECU 100 does not supply the signal pressure P3 from the on / off solenoid valve 670 to the signal pressure port 664, so that the input port 661 communicates with the output port 663. Yes. On the other hand, when setting the sheave pressure switching valve 660 to the fail state, the ECU 100 causes the signal pressure port 664 to supply the signal pressure P3 from the on / off solenoid valve 670 so that the input port 662 communicates with the output port 663. It has become.

  Oil is supplied to the on / off solenoid valve 670 through an oil passage (not shown). The on / off solenoid valve 670 controls the oil pressure of the supplied oil to a signal pressure P6 that determines the communication state between the input port 661 of the sheave pressure switching valve 660 and the output port 663 of the input port 662, and the sheave pressure switching valve 660. It comes to supply.

  Therefore, the primary sheave pressure regulating valve 620 passes the oil supplied from the line pressure modulator valve 610 during normal operation of the CVT 70 from the input port 661 of the sheave pressure switching valve 660 to the output port 663 of the sheave pressure switching valve 660. Then, it is supplied to the input side hydraulic cylinder 73 of the primary pulley 72. That is, the primary sheave pressure regulating valve 620 controls the primary sheave pressure Pin supplied to the hydraulic chamber of the input side hydraulic cylinder 73 of the movable sheave 72a of the primary pulley 72 when the CVT 70 is normal.

  The secondary sheave pressure regulating valve 640 supplies oil supplied from the line pressure modulator valve 610 from the input port 662 of the sheave pressure switching valve 660 when at least one of the primary sheave pressure regulating valve 620 and the shift solenoid valve 630 fails. The oil is supplied to the input side hydraulic cylinder 73 of the primary pulley 72 through a path to the output port 663 of the switching valve 660. That is, the secondary sheave pressure regulating valve 640 controls the primary sheave pressure Pin supplied to the hydraulic chamber of the input side hydraulic cylinder 73 of the movable sheave 72a of the primary pulley 72 when the CVT 70 fails.

  Further, the secondary sheave pressure regulating valve 640 supplies the oil supplied from the line pressure modulator valve 610 to the output side hydraulic cylinder 78 of the secondary pulley 77 during normal operation and failure of the CVT 70. That is, the secondary sheave pressure regulating valve 640 controls the secondary sheave pressure supplied to the hydraulic chamber of the output side hydraulic cylinder 78 of the movable sheave 77a of the secondary pulley 77, that is, the belt clamping pressure Pd.

  The control device for the continuously variable transmission according to the present embodiment includes a CVT 70 and a hydraulic control circuit 31, and controls the forward clutch pressure Pc with a predetermined hydraulic gradient to release the forward clutch 64 when the vehicle 10 is stopped. The garage control for switching from the state to the engaged state can be executed. In this specification, the case where the garage control is performed during traveling is particularly referred to as traveling garage control. Since the garage control is the same as the known or new garage control, detailed description thereof is omitted.

  Further, the control device for the continuously variable transmission according to the present embodiment switches the sheave pressure switching valve 660 to the fail state when at least one of the primary sheave pressure regulating valve 620 or the shift solenoid valve 630 fails, and the forward clutch The forward clutch 64 is switched to the released state by controlling the pressure Pc. In this case, the control device for the continuously variable transmission according to the present embodiment controls the forward clutch pressure Pc to bring the forward clutch 64 into an engaged state when the vehicle speed V has decreased to a speed at which the forward clutch 64 can be engaged. It is supposed to switch. Further, in this case, the hydraulic gradient of the forward clutch pressure Pc when the forward clutch 64 is switched to the engaged state is higher than a predetermined hydraulic gradient in the garage control.

  Next, the operation will be described.

  The ECU 100 executes processing of the following continuously variable transmission control program at predetermined time intervals of, for example, 10 ms. As shown in FIG. 5, ECU 100 determines whether or not a downshift failure has occurred in CVT 70 while vehicle 10 is traveling (step S1). Whether or not a downshift failure has occurred in the CVT 70 is determined based on the fact that the set gear ratio γ deviates from the actual gear ratio γ and the actual gear ratio γ changes to the lowest side. It is judged by. When ECU 100 determines that no downshift failure has occurred in CVT 70 (step S1; NO), ECU 100 returns the process to the main routine.

  When ECU 100 determines that a downshift failure has occurred in CVT 70 (step S1; YES), ECU 100 switches sheave pressure switching valve 660 to the fail state (step S2). Thereby, the ECU 100 switches the supply pressure to the primary pulley 72 from the primary sheave pressure Pin to the belt clamping pressure Pd, and switches the supply pressure to the forward clutch 64 from the signal pressure Pslu to the control pressure P4.

  The ECU 100 controls the starting clutch pressure regulating valve 520 to switch the forward clutch 64 to the released state (step S3). As a result, the belt clamping pressure Pd is supplied to both the primary pulley 72 and the secondary pulley 77. Therefore, the speed ratio γ is a predetermined value determined by the pressure receiving area difference between the hydraulic cylinders 73 and 78, for example, 1. The vehicle 10 gradually decelerates while coasting (step S4).

ECU100 the vehicle speed V is determined whether it is the predetermined speed _{V 1} or less (step S5). Here, the predetermined speed V ₁ is a speed at which the forward clutch 64 set in advance can be engaged. As the predetermined speed _{V 1,} it can be set to, for example, about an hour 25km. Of course, the predetermined speed is not limited to 25 km / h.

ECU100 is, the vehicle speed V is when it is determined that it is not at a predetermined speed _{V 1} or less (step S5; NO), the deceleration by coasting is maintained (step S4). If the ECU 100 determines that the vehicle speed V is the predetermined speed _{V 1} or less (step S5; YES), ECU 100 controls the starting clutch pressure regulator valve 520, engaged forward clutch 64 by the linear pressure (Step S6). At this time, the hydraulic gradient of the forward clutch pressure Pc when the forward clutch 64 is switched to the engaged state is higher than a predetermined hydraulic gradient in the garage control. As a result, the vehicle 10 can be accelerated and controlled by the engine 11. Therefore, the ECU 100 can ensure acceleration in the retreat travel of the vehicle 10 and increase the degree of freedom.

Then, ECU 100 switches from the vehicle speed V is lower than the predetermined speed _{V 2} of the sheave pressure switching valve 660 to the normal state (step S7). Here the predetermined speed V ₂ in is the rate at which the speed ratio of CVT70 gamma is preset so that the outermost Low before stopping. Thus, ECU 100 switches the supply pressure to primary pulley 72 from belt clamping pressure Pd to primary sheave pressure Pin, and switches the supply pressure to forward clutch 64 from control pressure P4 to signal pressure Pslu.

  Here, since at least one of the primary sheave pressure regulating valve 620 and the shift solenoid valve 630 has failed, the primary sheave pressure Pin is not supplied, for example. For this reason, in the CVT 70, the primary pulley 72 is not controlled and only the secondary pulley 77 is controlled. Therefore, the width of the V groove in the secondary pulley 77 is narrowed, and the speed ratio γ changes to the lowest side. Then, before the vehicle stops, the speed ratio γ becomes the lowest level (step S8). After the gear ratio γ reaches the lowest level, the vehicle speed V becomes 0 and the vehicle 10 stops (step S9). Therefore, the CVT gear ratio at the next start can be set to the lowest level.

  Next, an operation when a downshift failure occurs in the CVT 70 in the traveling vehicle 10 will be described with reference to a time chart shown in FIG.

Vehicle 10 downshift failure occurs CVT70 at _{T 0} during running. Thereby, since at least one of the primary sheave pressure regulating valve 620 and the shift solenoid valve 630 has failed, the primary sheave pressure Pin is not supplied, for example. In the CVT 70, the primary pulley 72 is not controlled and only the secondary pulley 77 is controlled. Therefore, the width of the V groove in the secondary pulley 77 is narrowed, and the speed ratio γ is changed to the lowest side. Along with this, the vehicle speed V is decelerated.

The ECU 100 determines that the set gear ratio γ deviates from the actual gear ratio γ at T ₁ and a downshift failure occurs in the CVT 70 based on the fact that the actual gear ratio γ changes to the lowest side. Judge that Then, ECU 100 switches sheave pressure switching valve 660 from the normal state to the fail state. Thereby, the ECU 100 switches the supply pressure to the primary pulley 72 from the primary sheave pressure Pin to the belt clamping pressure Pd, and switches the supply pressure to the forward clutch 64 from the signal pressure Pslu to the control pressure P4.

  As a result, the belt clamping pressure Pd is supplied to both the primary pulley 72 and the secondary pulley 77. Therefore, the speed ratio γ is a predetermined value determined by the pressure receiving area difference between the hydraulic cylinders 73 and 78, for example, 1. Further, the ECU 100 controls the starting clutch pressure regulating valve 520 to switch the forward clutch 64 to the released state.

When the vehicle speed V is reduced to a predetermined speed _{V 1} at T _2, ECU 100 controls the starting clutch pressure regulator valve 520, it switches the forward clutch 64 in the engaged state by the linear pressure. As a result, the vehicle 10 can be accelerated and controlled by the engine 11. Therefore, the ECU 100 can ensure acceleration in the retreat travel of the vehicle 10 and increase the degree of freedom.

  Further, the hydraulic gradient of the forward clutch pressure Pc when the forward clutch 64 is switched to the engaged state is higher than a predetermined hydraulic gradient in the garage control. For this reason, since the forward clutch 64 can be quickly switched to the engaged state, the timing for switching the sheave pressure switching valve 660 from the fail state to the normal state can be made earlier. Therefore, since it is possible to secure a long time for the speed ratio γ to become the lowest, it is possible to improve the accuracy for making the speed ratio the lowest.

When the vehicle speed V is reduced to a predetermined speed _{V 2} at T _3, ECU 100 switches the sheave pressure switching valve 660 to the normal state. Thus, ECU 100 switches the supply pressure to primary pulley 72 from belt clamping pressure Pd to primary sheave pressure Pin, and switches the supply pressure to forward clutch 64 from control pressure P4 to signal pressure Pslu. As a result, the gear ratio γ changes to the lowest side. Then, the gear ratio γ is the outermost Low in T ₄ is a front stop of the vehicle. Speed ratio γ from becoming the lowest Low, the vehicle speed V at T ₅ is the vehicle 10 is stopped becomes 0. Therefore, the CVT gear ratio at the next start can be set to the lowest level.

  As described above, according to the control device for continuously variable transmission according to the present embodiment, ECU 100 controls forward clutch pressure Pc when vehicle speed V drops to a speed at which forward clutch 64 can be engaged. Since the forward clutch 64 is switched to the engaged state, the power from the engine 11 can be used earlier than in the prior art. Thereby, the restriction | limiting of the retreat driving | running | working of the vehicle 10 is reduced conventionally.

  Further, according to the continuously variable transmission control device according to the present embodiment, the hydraulic gradient of the forward clutch pressure Pc when the forward clutch 64 is switched to the engaged state is higher than the predetermined hydraulic gradient in the garage control. The forward clutch 64 can be quickly switched to the engaged state. For this reason, since the timing for switching the sheave pressure switching valve 660 from the fail state to the normal state can be made earlier, it is possible to secure a long time for the transmission gear ratio γ of the CVT 70 to become the lowest, so that the transmission gear ratio can be maximized. The accuracy for setting to Low can be improved.

  Further, according to the control device for continuously variable transmission according to the present embodiment, sheave pressure switching valve 660 and garage switching valve 510 are configured by a common valve, and sheave pressure switching valve 660 is a starting clutch in the fail state. The pressure regulating valve 520 and the forward clutch 64 are communicated with each other. As a result, the number of components is not increased by sharing the components, and the control in the ECU 100 can be simplified.

The control device for a continuously variable transmission of the embodiment described above, ECU 100, when the vehicle speed V is decelerated to a predetermined speed V _1, the starting clutch pressure regulating valve and the forward clutch 64 in step S6 shown in FIG. 5 It is controlled by the direct pressure of 520. However, the continuously variable transmission control device according to the present invention is not limited to this, and for example, control as shown in FIG. 7 is also possible.

  The flowchart shown in FIG. 7 is a modification of step S6 of the flowchart shown in FIG. Accordingly, Steps S1 to S5 and Steps S7 to S9 are the same and will not be described.

As shown in FIG. 7, ECU 100 is, when the vehicle speed V is determined that the predetermined speed _{V 1} or less, ECU 100 may, Tc is equal to or greater than or equal to Tg (step S61).

Here, Tc is sheave pressure switching valve 660 subtracts the current vehicle speed V from the lower limit vehicle speed V ₃ that can reliably speed ratio γ until stopped by the normal state on the outermost Low, the calculated difference current This is the time divided by the vehicle deceleration, and means a margin time during which the gear ratio γ can be set to the lowest level. Tg means the time required to bring the forward clutch 64 into the engaged state by the normal traveling garage control.

  When the ECU 100 determines that Tc is equal to or greater than Tg (step S61; YES), the ECU 100 switches the forward clutch 64 to the engaged state by the running garage control (step S62).

When it is determined that Tc is not equal to or greater than Tg (step S61; NO), the ECU 100 switches the forward clutch 64 to the engaged state by a predetermined sweep amount dP, that is, a hydraulic pressure that increases by a predetermined amount per unit time ( Step S63). Here, ECU 100 is necessary to engage the forward clutch 64 and the absolute value of the clutch pressure required for engagement of the forward clutch 64 divided by Tc, i.e. up to the current vehicle speed V is lowered to the lower limit vehicle speed V ₃ The hydraulic pressure is a sweep amount dP.

  Here, if Tc is not equal to or greater than Tg, the ECU 100 may not be able to shift the gear ratio γ to the lowest level until the vehicle stops even if the hydraulic pressure is supplied to the forward clutch 64 with a hydraulic gradient similar to that in the garage control. . However, in the present embodiment, when Tc is not equal to or greater than Tg, ECU 100 causes the hydraulic gradient of forward clutch pressure Pc when switching forward clutch 64 to the engaged state is higher than a predetermined hydraulic gradient in garage control. Therefore, the forward clutch 64 can be quickly switched to the engaged state. For this reason, since the timing for switching the sheave pressure switching valve 660 from the fail state to the normal state can be made earlier, it is possible to secure a longer time for the gear ratio γ of the CVT 70 to become the lowest, and to further increase the gear ratio γ. It can surely be set to the lowest level. In addition, since the ECU 100 can ensure a long time for the transmission gear ratio γ of the CVT 70 to be the lowest, it is possible to improve the accuracy for setting the transmission gear ratio γ to the lowest.

  As described above, in the continuously variable transmission control device according to the present invention, in a vehicle equipped with a CVT, when the primary sheave pressure supply system fails during retreat and stops, the CVT shift at the next start is performed. The effect is that the ratio can be made the lowest, and it is useful for a control device for a continuously variable transmission.

10 Vehicle 11 Engine (drive source)
15 Crankshaft (drive shaft)
31 Hydraulic control circuit 45 Drive wheel 64 Forward clutch (starting clutch)
70 CVT (continuously variable transmission)
70a Input shaft 72 Primary pulley (drive pulley)
75 Belt 77 Secondary pulley (driven pulley)
79 Secondary shaft (output shaft)
100 ECU (control device for continuously variable transmission)
520 Starting clutch pressure regulating valve 620 Primary sheave pressure regulating valve (primary sheave pressure supplying means)
630 Variable speed solenoid valve (primary sheave pressure supply means)
640 Secondary sheave pressure regulating valve (secondary sheave pressure supply means)
650 Belt clamping solenoid valve (secondary sheave pressure supply means)
660 Sheave pressure switching valve Pc Starting clutch pressure Pd Belt clamping pressure (secondary sheave pressure)
Pin primary sheave pressure

Claims (2)

An input shaft to which rotational power is transmitted from a drive shaft of a drive source of a vehicle, an output shaft for transmitting the rotational power to a drive wheel, an engagement state in which the input shaft and the output shaft are engaged, and A starting clutch that switches a transmission state between a release state that releases between the input shaft and the output shaft, a driving pulley connected to the input shaft, a driven pulley connected to the output shaft, A belt wound around the driving pulley and the driven pulley, and by supplying hydraulic oil to at least one of the driving pulley and the driven pulley, the driving pulley and the A stepless change in which the gear ratio is continuously controlled by changing the belt clamping pressure from the driven pulley to the belt and changing the effective winding diameter of the driving pulley and the driven pulley. And the machine,
Primary sheave pressure supply means for generating primary sheave pressure, secondary sheave pressure supply means for supplying secondary sheave pressure to the driven pulley, a normal state in which the primary sheave pressure is supplied to the drive pulley, and the secondary sheave A sheave pressure switching valve capable of switching between at least two states of a fail state for supplying pressure to the driving pulley and the driven pulley, and a starting clutch for adjusting the starting clutch pressure supplied to the starting clutch A hydraulic control circuit having a pressure regulating valve,
A control device for a continuously variable transmission capable of executing garage control for controlling the starting clutch pressure with a predetermined hydraulic pressure gradient to switch the starting clutch from the released state to the engaged state when the vehicle is stopped;
When the primary sheave pressure supply means fails, the sheave pressure switching valve is switched to the fail state, and the starting clutch pressure is controlled to switch the starting clutch to the released state.
When the vehicle speed decreases to a speed at which the start clutch can be engaged, the start clutch pressure is controlled to switch the start clutch to the engaged state, and then the sheave pressure switching valve is switched to the normal state. While shifting the gear ratio to the maximum gear ratio,
A control device for a continuously variable transmission, wherein a hydraulic pressure gradient of the starting clutch pressure when the starting clutch is switched to the engaged state is higher than the predetermined hydraulic pressure gradient in the garage control.   2. The continuously variable transmission control device according to claim 1, wherein the sheave pressure switching valve enables the hydraulic oil to flow from the starting clutch pressure regulating valve to the starting clutch in the fail state.

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