JP4715051B2 - Hydraulic control device for continuously variable transmission - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydraulic control device for a continuously variable transmission, and more particularly to an improvement of a hydraulic control device having a pair of shift control valves for upshifting and downshifting.
[0002]
[Prior art]
(a) a continuously variable transmission in which the transmission ratio is reduced by supplying hydraulic oil to the transmission hydraulic actuator, and the transmission ratio is increased by discharging hydraulic oil from the transmission hydraulic actuator; (b) An upshift shift control valve connected to the shift hydraulic actuator and supplying hydraulic oil to the shift hydraulic actuator to reduce a gear ratio; and (c) a shift hydraulic pressure connected to the shift hydraulic actuator. 2. Description of the Related Art A hydraulic control device for a continuously variable transmission having a downshift transmission control valve that discharges hydraulic oil from an actuator to increase a transmission ratio is known. The device described in Japanese Patent Application Laid-Open No. 11-182657 is an example, and is used in a vehicle drive device. A belt-type continuously variable transmission is used as a continuously variable transmission, and its input side is variable. The hydraulic cylinder of the pulley is a shift hydraulic actuator. When hydraulic oil is supplied and the V groove width is narrowed, the belt engagement diameter increases and the gear ratio is reduced, and the hydraulic oil is discharged and V As the groove width increases, the belt engagement diameter decreases, and the downshift is performed so that the transmission ratio increases.
[0003]
  Figure6FIG. 2 is a diagram showing a main part of the hydraulic control device for the belt type continuously variable transmission, that is, a hydraulic circuit 100 for shift control, and includes an electromagnetic valve 102 for upshift, a flow control valve 104, and an electromagnetic valve for downshift. 106 and a flow control valve 108, and when the upshift solenoid valve 102 is duty-controlled by a CVT controller (not shown), a predetermined upshift signal pressure P obtained by reducing the modulator pressure PM._VUIs output to the flow control valve 104 and its upshift signal pressure P_VUThe line pressure PL is supplied from the line oil passage 110 through the supply oil passage 112 to the hydraulic cylinder of the input-side variable pulley 114 at a flow rate corresponding to Shifted. When the downshift solenoid valve 106 is duty-controlled by the CVT controller, a predetermined downshift signal pressure P obtained by reducing the modulator pressure PM is obtained._VDIs output to the flow control valve 108 and its downshift signal pressure P_VDWhen the drain port 116 is opened at an opening corresponding to, hydraulic oil in the input side variable pulley 114 is drained from the discharge oil passage 118 at a predetermined flow rate, and the V groove width of the input side variable pulley 114 becomes wide. Downshifted. The electromagnetic valve 102 and the flow control valve 104 correspond to an upshift transmission control valve, and the electromagnetic valve 106 and the flow control valve 108 correspond to a downshift transmission control valve.
[0004]
On the other hand, even when one of the solenoid valves 102, 106 fails due to a failure in the electrical system, a sudden upshift or downshift may occur, or belt slip may occur due to the sudden shift. In order to prevent this, the upshift signal pressure P output from the solenoid valve 102_VUIs supplied to the flow control valve 108 for downshift, so that the downshift signal pressure P_VDRegardless of this, the flow control valve 108 is closed to limit the downshift, while the downshift signal pressure P output from the solenoid valve 106 is_VDIs supplied to the flow control valve 104 for upshift, and the upshift signal pressure P_VURegardless of this, the flow control valve 104 can be closed to limit the upshift.
[0005]
Further, for example, as shown in FIG. 5, the shift control of the continuously variable transmission is performed by an accelerator operation amount θ representing the driver's output request amount._ACCThe target rotational speed NINT on the input side is calculated from a predetermined shift map using the vehicle speed V as a parameter, and the input rotational speed NIN matches the target rotational speed NINT so that the actual input shaft rotational speed NIN matches the target rotational speed NINT. The duty ratios of the electromagnetic valves 102 and 106 are feedback controlled to control the supply and discharge of hydraulic fluid to and from the hydraulic cylinder of the input side variable pulley 114. In this case, if the valve body of the flow control valve 108 for downshift is mechanically fixed (valve stick) to the drain side, that is, the downshift side due to the foreign matter being caught or the like, the gearshift ratio γ Since the input shaft rotational speed NIN of the continuously variable transmission becomes higher than the target rotational speed NINT, the flow control valve 104 for upshift is controlled to be opened by feedback control, but the flow control valve 108 is opened. Therefore, the line pressure PL supplied to the supply oil passage 112 is drained from the discharge oil passage 118 through the flow control valve 108 as it is, and a sudden downshift occurs or the line pressure PL decreases. There is a fear. In addition, if the vehicle is downshifted to the maximum gear ratio γmax during high-speed traveling at a high vehicle speed V, the rotational speed of the drive source such as the engine may overrun (abnormally increase) and cause irreparable damage. For this reason, the high vehicle speed range (vehicle speed V in FIG.₁In the above, a duty guard for limiting the duty ratio of the electromagnetic valve 106 for downshifting to a predetermined value (for example, about 60%) or less is provided, and the drain opening degree of the flow control valve 108 is limited to temporarily set the valve stick. Even if this occurs, it is considered to avoid a sudden downshift, excessive decrease in the line pressure PL, and accompanying overrun of the drive source.
[0006]
[Problems to be solved by the invention]
However, if the drain flow rate of the flow control valve for downshift is limited in this way, the shift speed of the downshift is slowed, so that there is a problem that the responsiveness of the increase in driving force with respect to the accelerator operation is impaired.
[0007]
The present invention has been made against the background of the above circumstances, and its purpose is to make a sudden downshift caused by the valve stick of the shift control valve for downshift without impairing the shift response of the downshift. It is intended to prevent excessive reduction of the line pressure and overrun of the drive source.
[0008]
[Means for Solving the Problems]
  In order to achieve such an object, according to the first aspect of the present invention, (a) the transmission gear ratio is reduced by supplying hydraulic oil to the transmission hydraulic actuator, and the transmission oil is discharged from the transmission hydraulic actuator. A continuously variable transmission having a large ratio; and (b) connected to the shift hydraulic actuator, and supplying hydraulic oil to the shift hydraulic actuator to reduce the gear ratio.At the same time, the speed can be changed continuouslyAn upshift transmission control valve; and (c) connected to the transmission hydraulic actuator, and discharges hydraulic fluid from the transmission hydraulic actuator to increase the transmission ratio.At the same time, the speed can be changed continuouslyA hydraulic control device for a continuously variable transmission having a downshift transmission control valve, wherein (d) hydraulic fluid of the transmission hydraulic actuator is provided between the transmission hydraulic actuator and the downshift transmission control valve. During downshift control that discharges and increases the gear ratio, hydraulic fluid is allowed to flow to the downshift transmission control valve side, but hydraulic fluid is supplied from the upshift transmission control valve to the transmission hydraulic actuator. An open / close valve device that restricts the flow of hydraulic fluid to the downshift gear control valve side during upshift control to reduce the gear ratio.And (e) the on-off valve device is configured integrally with the upshift transmission control valve, and the upshift transmission control valve is connected to the (e-1) hydraulic oil supply source. Supply port, a CVT port connected to the shift hydraulic actuator, and a downshift port connected to the downshift control valve, and (e-2) the valve body is in its original position. When held, the CVT port communicates with the downshift port to allow hydraulic fluid to flow from the shift hydraulic actuator to the downshift transmission control valve, but the valve body is upshifted. The supply port and the CVT port communicate with each other to supply hydraulic oil to the speed change hydraulic actuator and shut down the downshift port. The flow of hydraulic oil to the shift control valve sideIt is characterized by that.
[0010]
【The invention's effect】
In such a continuously variable transmission hydraulic control device, an on-off valve device is provided between the shift hydraulic actuator and the downshift gearshift control valve, and is operated to the downshift gearshift control valve side during the downshift control. Oil is allowed to flow, but the upshift control restricts the flow of hydraulic oil to the downshift transmission control valve side, so the downshift transmission control valve is valve sticked in a fully open state, for example. Even in this case, when the upshift control is performed to achieve a predetermined gear ratio, the flow of hydraulic oil to the downshift transmission control valve side is restricted by the on-off valve device, so that the downshift is suppressed or increased. It becomes a shift. This prevents a sudden downshift, an excessive decrease in line pressure, an overrun of the drive source due to an excessive downshift at a high vehicle speed range, regardless of the valve stick of the downshift transmission control valve. . In addition, because it does not limit the drain opening of the downshift transmission control valve, the downshift transmission control valve is controlled to open fully in accordance with the amount of accelerator operation during normal operation, resulting in excellent shift response. Is obtained.
[0011]
  Also,Since the on-off valve device is configured integrally with the upshift transmission control valve, the device is simpler and more compact than the case where it is provided separately, and the upshift transmission control valve is only controlled to open / close. Since the on-off valve device is also opened and closed, the conventional shift control can be applied as it is.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The present invention is preferably applied to a continuously variable transmission of a vehicle drive device, but can also be applied to a continuously variable transmission such as an industrial machine. As the continuously variable transmission, (a) an input-side variable pulley and an output-side variable pulley whose effective diameter is variable, and (b) a transmission belt that is wound around these variable pulleys and transmits power by frictional force, A belt-type continuously variable transmission having the above is preferably used, but may be applied to other continuously variable transmissions such as a toroidal-type continuously variable transmission.
[0013]
The speed control of the continuously variable transmission is obtained by, for example, obtaining a target speed ratio according to a predetermined speed condition so that the actual speed ratio becomes the target speed ratio, or inputting according to the vehicle speed, the output shaft rotational speed, etc. It is possible to adopt various modes such as obtaining the target rotational speed on the side and performing feedback control so that the actual input shaft rotational speed becomes the target rotational speed. The target rotational speed on the input side corresponds to the target gear ratio, and it is not always necessary to obtain the target gear ratio itself.
[0014]
The predetermined speed change condition is set by a map or an arithmetic expression using, for example, a driver output request amount such as an accelerator operation amount and a driving state such as a vehicle speed (corresponding to an output shaft rotation speed) as parameters. Note that the gear ratio need not always be automatically controlled, and the driver may arbitrarily change the gear ratio by manual operation under certain conditions such as during traveling at a predetermined vehicle speed or higher.
[0015]
  Each shift control valve for upshifts and downshifts can continuously change the flow rate, that is, the shift speed, depending on the flow cross-sectional area of hydraulic oil, the opening and closing time, etc.so,For example, it is configured with a solenoid valve or linear solenoid valve.The
[0016]
The on-off valve device is configured to completely prevent hydraulic fluid from flowing to the downshift transmission control valve side during upshift control, for example, but a sudden downshift at the time of valve stick of the downshift transmission control valve As long as excessive reduction of the line pressure or excessive downshift in the high vehicle speed range can be prevented, the hydraulic oil may flow to the downshift transmission control valve side to some extent.
[0017]
AThe shift control valve for upshift is,valveWhen the body moves to the upshift side, the supply source port and the CVT port are communicated to supply hydraulic oil to the shift hydraulic actuator, and the downshift port is shut off and the downshift shift control valve Configured to restrict the flow of hydraulic fluid to the sideBut at that timeThe shut-off of the downshift port may completely block the flow of hydraulic oil to the downshift transmission control valve side.AndIt may be one that allows a certain amount of distribution.
[0018]
【Example】
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a skeleton diagram of a vehicle drive device 10 to which the present invention is applied. This vehicle drive device 10 is of a horizontal type and is suitably employed in an FF (front engine / front drive) type vehicle, and includes an engine 12 as an internal combustion engine used as a drive source for traveling. The output of the engine 12 is transmitted from the torque converter 14 to the differential gear device 22 via the forward / reverse switching device 16, the belt-type continuously variable transmission (CVT) 18, and the reduction gear 20, and the left and right drive wheels 24L, 24R. Distributed to.
[0019]
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 forward / reverse switching device 16 via a turbine shaft 34, and transmits power through a fluid. Is supposed to do. Further, a lock-up clutch 26 is provided between the pump impeller 14p and the turbine impeller 14t so that they can be integrally connected to rotate integrally. The pump impeller 14p is provided with a mechanical oil pump 28 that generates hydraulic pressure for controlling the speed of the continuously variable transmission 18, generating belt clamping pressure, or supplying lubricating oil to each part. It has been.
[0020]
The forward / reverse switching device 16 is composed of a double pinion type planetary gear device. The turbine shaft 34 of the torque converter 14 is connected to the sun gear 16s, and the input shaft 36 of the continuously variable transmission 18 is connected to the carrier 16c. ing. Then, when the forward clutch 38 disposed between the carrier 16c and the sun gear 16s is engaged, the forward / reverse switching device 16 is rotated integrally so that the turbine shaft 34 is directly connected to the input shaft 36, and the forward direction. Is transmitted to the drive wheels 24R, 24L. Further, when the reverse brake 40 disposed between the ring gear 16r and the housing is engaged and the forward clutch 38 is released, the input shaft 36 is rotated reversely with respect to the turbine shaft 34, The driving force in the reverse direction is transmitted to the drive wheels 24R and 24L.
[0021]
The continuously variable transmission 18 includes an input-side variable pulley 42 having a variable effective diameter provided on the input shaft 36, an output-side variable pulley 46 having a variable effective diameter provided on the output shaft 44, and a variable thereof. A transmission belt 48 wound around pulleys 42 and 46 is provided, and power is transmitted through a frictional force between the variable pulleys 42 and 46 and the transmission belt 48. Each of the variable pulleys 42 and 46 has a variable V groove width and is configured to include a hydraulic cylinder. The hydraulic pressure of the hydraulic cylinder of the input side variable pulley 42 is controlled by a shift control circuit 50 (see FIG. 2). The V groove width of both variable pulleys 42 and 46 is changed to change the engagement diameter (effective diameter) of the transmission belt 48, and the gear ratio γ (= input shaft rotational speed NIN / output shaft rotational speed NOUT) is continuously increased. Can be changed. The hydraulic cylinder of the input side variable pulley 42 corresponds to a shift hydraulic actuator, and the shift control circuit 50 corresponds to a hydraulic control device.
[0022]
FIG. 3 shows an example of the speed change control circuit 50. The upshift solenoid valve 52 and the flow rate control valve 54 for reducing the speed ratio γ, and the downshift solenoid valve 56 and the flow rate control valve for increasing the speed ratio γ. 58. The up-shift electromagnetic valve 52 and the flow control valve 54 function as an up-shift transmission control valve and an on-off valve device. The flow control valve 54 is connected to a line oil passage 64 that is a supply source of hydraulic oil. Downshift connected to the flow control valve 58 for downshift via the supply source port 54a, the CVT port 54b connected to the hydraulic cylinder of the input side variable pulley 42 via the CVT oil passage 60, and the drain oil passage 62 When the valve body (spool) 54d is held in its original position in accordance with the urging force of the spring 54g as shown in FIG. 3, the CVT port 54b and the downshift port 54c are communicated with each other. After the hydraulic oil of the hydraulic cylinder of the input side variable pulley 42 passes through the CVT oil passage 60 and the discharge oil passage 62, the flow control for downshifting is performed. It allows to distribution to 58. On the other hand, the upshift electromagnetic valve 52 is duty-controlled by the CVT controller 80 (see FIG. 2), and a predetermined upshift signal pressure P obtained by reducing the modulator pressure PM._VUIs supplied to the signal pressure chamber 54e, the valve element 54d has its upshift signal pressure P_VUAccordingly, it is moved to the upshift side (upward in FIG. 3) against the urging force of the spring 54g, and the supply source port 54a and the CVT port 54b are connected to each other, so that the line pressure PL is changed to the upshift signal pressure P._VUIs supplied from the supply oil passage 60 to the hydraulic cylinder of the input-side variable pulley 42 at a flow rate corresponding to the above, the V-groove width of the input-side variable pulley 42 becomes narrower, and the continuously variable transmission 18 is upshifted and downshifted. Port 54c is shut off, and the flow of hydraulic fluid to the downshift flow control valve 58 side is prevented. Even in the state where the valve body 54d is held in the original position, the line oil passage 64 and the CVT oil passage 60 are communicated with each other with a small flow cross-sectional area, and a predetermined hydraulic pressure is applied to cause a gear ratio due to oil leakage or the like. It is designed to prevent changes.
[0023]
The downshift solenoid valve 56 and the flow control valve 58 function as a downshift transmission control valve. The flow control valve 58 is connected to the CVT port 58a connected to the drain oil passage 62 and the drain oil passage. When the valve body (spool) 58c is held in its original position in accordance with the urging force of the spring 58g as shown in FIG. 58b is communicated, and the hydraulic oil is drained with a slight flow rate of a leakage level. On the other hand, the solenoid valve 56 is duty-controlled by the CVT controller 80, and a predetermined downshift signal pressure P obtained by reducing the modulator pressure PM._VDIs supplied to the signal pressure chamber 58d, the valve body 58c has its downshift signal pressure P_VDAccordingly, it is moved to the downshift side (upward in FIG. 3) against the biasing force of the spring 58g, and the downshift signal pressure P_VDThe CVT port 58a and the drain port 58b are communicated with each other at the drain opening corresponding to the hydraulic pressure of the hydraulic cylinder of the input side variable pulley 42, and the downshift signal pressure P_VDThe drain oil passage 62 is drained at a flow rate corresponding to the above, and the V-groove width of the input side variable pulley 42 is widened and downshifted. The flow control valve 58 is also provided with a hydraulic replenishment port 58e connected to the line oil passage 64 via a check valve 66, and has a predetermined flow cross-sectional area in a state where the valve body 58c is held in its original position. Even if the continuously variable transmission 18 does not return to the maximum gear ratio γmax when the vehicle is stopped by communicating with the CVT port 58a and applying a predetermined hydraulic pressure to the input side variable pulley 42, the input side variable pulley at start 42 opens to prevent belt slippage.
[0024]
The upshift signal pressure P output from the upshift solenoid valve 52_VUIs supplied to the backup chamber 58f of the flow control valve 58 for downshift, and the downshift signal pressure P_VDRegardless of this, the flow control valve 58 is closed to limit the downshift, while the downshift signal pressure P output from the downshift electromagnetic valve 56 is reduced._VDIs supplied to the backup chamber 54f of the flow control valve 54 for the upshift, and the upshift signal pressure P_VURegardless, the flow control valve 54 is closed to prohibit upshifting. As a result, one of the solenoid valves 52 and 56 does not function due to a failure of the electrical system, and the upshift signal pressure P_VUOr downshift signal pressure P_VDEven when the output remains at the maximum pressure, it is possible to prevent sudden upshifts and downshifts, and belt slippage due to the sudden shift.
[0025]
On the other hand, the hydraulic pressure of the hydraulic cylinder of the output side variable pulley 46 is regulated by a clamping pressure control circuit 70 (see FIG. 2) so that the transmission belt 48 does not slip. The clamping pressure control circuit 70 includes a linear solenoid valve whose duty is controlled by the CVT controller 80, and the hydraulic pressure of the hydraulic cylinder of the output side variable pulley 46 is continuously controlled by the linear solenoid valve. The belt clamping pressure, that is, the frictional force between the variable pulleys 42 and 46 and the transmission belt 48 is increased or decreased.
[0026]
The CVT controller 80 shown in FIG. 2 includes a microcomputer, and performs signal processing according to a program stored in advance in the ROM while utilizing the temporary storage function of the RAM, thereby controlling the shift of the continuously variable transmission 18. Shift position sensor 82, accelerator operation amount sensor 84, engine rotation speed sensor 86, output shaft rotation speed sensor 88, input shaft rotation speed sensor 90, and the like. Accelerator pedal operation amount θ_ACCIn addition, signals representing the engine rotational speed NE, the output shaft rotational speed NOUT (corresponding to the vehicle speed V), the input shaft rotational speed NIN, and the like are supplied.
[0027]
The shift control by the CVT controller 80 is, for example, as shown in FIG._ACCFurther, a target rotational speed NINT on the input side is calculated from a predetermined shift map using the vehicle speed V as a parameter, and the actual input shaft rotational speed NIN is calculated according to such deviation so that it matches the target rotational speed NINT. The shift control of the step transmission 18, specifically, the electromagnetic valves 52 and 56 of the shift control circuit 50 are feedback controlled to control the supply and discharge of hydraulic oil to and from the hydraulic cylinder of the input side variable pulley 42. The map in FIG. 5 corresponds to the shift conditions, and the vehicle speed V is small and the accelerator operation amount θ_ACCThe target rotational speed NINT at which the gear ratio γ is increased as the value of is increased is set. Further, since the vehicle speed V corresponds to the output shaft rotational speed NOUT, the target rotational speed NINT, which is the target value of the input shaft rotational speed NIN, corresponds to the target speed ratio, and the minimum speed ratio γmin of the continuously variable transmission 18 and the maximum speed change. It is determined within the range of the ratio γmax. The shift map is stored in advance in a map storage device (ROM or the like) 92 of the CVT controller 80.
[0028]
Further, the clamping pressure control is performed, for example, as shown in FIG._ACCBy controlling the exciting current for the linear solenoid valve of the clamping pressure control circuit 70 in accordance with a map of a necessary hydraulic pressure (corresponding to the belt clamping pressure) determined in advance so that belt slip does not occur with the speed ratio γ as a parameter, The pressure regulation of the belt clamping pressure of the step transmission 18, specifically, the hydraulic pressure of the hydraulic cylinder of the output side variable pulley 46 is controlled. The necessary hydraulic pressure map in FIG. 4 corresponds to the clamping pressure control condition, and is stored in advance in the map storage device 92 of the CVT controller 80 in the same manner as the shift map.
[0029]
Here, in the shift control circuit 50 of the continuously variable transmission 18 of the present embodiment, the valve body 54d of the flow control valve 54 for the upshift has the upshift signal pressure P._VU, The downshift port 54c is shut off and the flow of hydraulic oil to the downshift flow control valve 58 side is blocked, so that the downshift flow control valve 58 is For example, even when the valve stick is fully opened, if the upshift control is performed so that the input shaft rotational speed NIN becomes the target rotational speed NINT by the downshift of the continuously variable transmission 18 accompanying the valve stick, The flow control valve 54 prevents the flow of hydraulic oil toward the downshift flow control valve 58, thereby preventing the downshift caused by the valve stick. As a result, regardless of the valve stick of the flow control valve 58 for downshift, there is a sudden downshift, an excessive decrease in the line pressure PL, an overrun of the engine 12 due to an excessive downshift at a high vehicle speed range, etc. Is prevented. In addition, since it does not limit the drain opening of the flow control valve 58 for downshifting, the accelerator operation amount θ is normal._ACCDepending on the above, the flow control valve 58 is controlled to be fully opened, so that excellent shift response can be obtained.
[0030]
In this embodiment, the downshift port 54c is provided in the upshift flow control valve 54, and the on-off valve device prevents the hydraulic fluid from flowing to the downshift flow control valve 58 side during the upshift control. Is integrally incorporated in the flow control valve 54 for upshifting, so that the speed change control circuit 50 is simpler and more compact than the case where it is provided separately, and the output output from the solenoid valve 52 is also increased. Shift signal pressure P_VUAccordingly, the downshift port 54c is also opened and closed simply by controlling the flow control valve 54 to open and close, and the conventional shift control can be applied as it is.
[0032]
As mentioned above, although the Example of this invention was described in detail based on drawing, this is an embodiment to the last, and this invention implements in the aspect which added various change and improvement based on the knowledge of those skilled in the art. Can do.
[Brief description of the drawings]
FIG. 1 is a skeleton diagram of a vehicle drive device to which the present invention is applied.
2 is a block diagram illustrating a control system of a continuously variable transmission in the vehicle drive device of FIG. 1; FIG.
FIG. 3 is a circuit diagram showing a specific example of the shift control circuit of FIG. 2;
4 is a diagram showing an example of a necessary oil pressure map used when obtaining a necessary oil pressure in the belt clamping pressure control performed by the CVT controller of FIG. 2; FIG.
FIG. 5 is a diagram showing an example of a shift map used when obtaining a target rotational speed NINT in the shift control performed by the CVT controller of FIG. 2;
FIG. 6 is a circuit diagram showing an example of a conventional shift control circuit.
[Explanation of symbols]
  18: Belt type continuously variable transmission 42: Input-side variable pulley (shift hydraulic actuator) 50: Shift control circuit (hydraulic control device) 52: Solenoid valve (upshift transmission control valve, on-off valve device) 54: Flow control Valve (shift control valve for upshift, open / close valve device)54a: Supply port 54b: CVT port 54c: Downshift port 54d: Valve body    56: Solenoid valve (shift control valve for downshift) 58: Flow control valve (shift control valve for downshift) 80: CVT controller 94: On-off valve device

Claims (1)

A continuously variable transmission in which the transmission gear ratio is reduced by supplying hydraulic oil to the transmission hydraulic actuator, and the transmission gear ratio is increased by discharging hydraulic oil from the transmission hydraulic actuator;
An upshift transmission control valve connected to the transmission hydraulic actuator, capable of supplying a hydraulic oil to the transmission hydraulic actuator to reduce a transmission ratio and continuously change a transmission speed ;
A shift control valve for downshift that is connected to the hydraulic actuator for shifting, discharges hydraulic fluid from the hydraulic actuator for shifting, increases the gear ratio, and continuously changes the gearshift speed ;
In a hydraulic control device of a continuously variable transmission having
During downshift control in which hydraulic oil of the gearshift hydraulic actuator is discharged and the gear ratio is increased between the gearshift hydraulic actuator and the gearshift control valve for downshift, the hydraulic fluid is moved to the gearshift control valve side for downshift. Is allowed to flow, but hydraulic fluid flows from the upshift transmission control valve to the downshift transmission control valve side during upshift control in which hydraulic fluid is supplied to the transmission hydraulic actuator to reduce the transmission ratio. Has an on-off valve device to limit that ,
The on-off valve device is configured integrally with the upshift transmission control valve, and the upshift transmission control valve is
A supply port connected to a hydraulic oil supply source, a CVT port connected to the shift hydraulic actuator, and a downshift port connected to the downshift control valve;
When the valve body is held in the original position, the CVT port and the downshift port are communicated to allow hydraulic oil to flow from the shift hydraulic actuator to the downshift transmission control valve. When the valve body moves to the upshift side, the supply source port and the CVT port are communicated to supply hydraulic oil to the shift hydraulic actuator, and the downshift port is shut off and the downshift shift is performed. A hydraulic control device for a continuously variable transmission, which restricts the flow of hydraulic oil to a control valve side .

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