JPH0321788B2 - - Google Patents

Description

[Detailed description of the invention]

Technical Field The present invention relates to a spool valve type shift speed control valve device used in a hydraulic system for a belt-type continuously variable transmission, and particularly when the shift speed control valve device is duty-controlled by increasing the responsiveness of switching operation. This invention relates to a technology that widens the range in which flow rate can be controlled with respect to changes in duty. Prior Art A first switching state in which hydraulic oil is supplied through a supply passage to a hydraulic cylinder for changing the effective diameter of a pair of variable pulleys provided in a belt-type continuously variable transmission, and a first switching state in which hydraulic oil is allowed to be discharged through a discharge passage. There is a hydraulic system that includes a shift direction switching valve device that can be selectively switched to a second switching state, and controls the changing direction of the gear ratio of a belt type continuously variable transmission by switching the shift direction switching valve device. For example, there is a device described in Japanese Patent Application No. 31298/1987 filed by the present applicant. If such a device is used in an automobile, it is possible to control the engine rotational speed to an optimum rotational speed by continuously changing the gear ratio according to the driving condition, so that a suitable fuel efficiency rate can be obtained. Such a device includes a valve body in which a cylinder bore is formed, a spool shaft and a plurality of spool lands formed in a large diameter part in the axial direction, and the valve body is slidably fitted into the cylinder bore. the spool valve; and a valve drive device that applies a predetermined hydraulic pressure to the end face of the spool valve to selectively position the spool valve in two positions in the axial direction. It is inserted into a supply passage through which hydraulic oil is supplied to the cylinder and a discharge passage through which hydraulic oil is discharged from the hydraulic cylinder, and as the spool valve element moves between the two positions, the spool land portion moves into the cylinder bore. By opening and closing a predetermined port that opens into the
A shift speed control valve device is used that adjusts the speed ratio change speed (shift speed) of the belt type continuously variable transmission by switching between a state where the flow of hydraulic oil in the supply passage and a discharge passage is allowed and a state where it is suppressed. There may be cases. Problems to be Solved by the Invention However, in such a shift speed control valve device, a pair of ports that communicate with the upstream side and the downstream side of the discharge passage, respectively, are used as ports involved in the flow of hydraulic oil in the discharge passage. A throttle port communicating with the throttle passage for suppressing the flow of hydraulic oil is provided, and when the flow of the hydraulic oil is allowed, the pair of ports are communicated with each other, and when the flow of the hydraulic oil is suppressed, the pair of ports are connected to each other. Generally, one of the ports is connected to the throttle port, and the axial dimension of the spool valve element is set relatively large. For this reason, the mass of the spool valve element becomes large, and the responsiveness of the switching operation of the shift speed control valve device is not necessarily sufficient, and when the shift speed control valve device is duty-controlled, the range in which the flow rate can be controlled relative to the duty ratio is limited. It was relatively narrow, making it difficult to control the speed of change of the gear ratio with high precision. The present invention has been made against the background of the above circumstances, and its object is to provide a spool valve type shift speed control valve device that has high responsiveness in switching operation. Means for Solving the Problems In order to achieve the above object, the gist of the present invention is to operate a hydraulic cylinder for changing the effective diameter of a pair of variable pulleys provided in a belt-type continuously variable transmission. A shift direction switching valve device that can be selectively switched between a first switching state in which oil is supplied through a supply passage and a second switching state in which hydraulic oil is allowed to be discharged through a discharge passage; In a hydraulic system for a belt-type continuously variable transmission that controls the direction of change in the gear ratio of the belt-type continuously variable transmission by switching, the state is inserted in the supply passage and the discharge passage to suppress the flow of the supply passage or the discharge passage. A spool valve-type shift speed control valve that continuously controls the speed of change of the gear ratio by periodically switching between two operating states: and a permitting state, and changing the time ratio of the two operating states. In the device, as a port involved in discharging hydraulic oil from inside the hydraulic cylinder,
Provided with only an upstream discharge oil port and a downstream discharge oil port that communicate with the upstream and downstream sides of the discharge passage, respectively, and in the permissible state, there is a gap between the upstream discharge oil port and the downstream discharge oil port. is opened, and in the suppressed state, the space between the upstream side discharge oil port and the downstream side discharge oil port is controlled to be closed. Operation and Effects of the Invention In such a shift speed control valve device,
Only an upstream discharge oil port and a downstream discharge oil port are provided as ports involved in the discharge of hydraulic oil from inside the hydraulic cylinder, and when the discharge passage is in a state that allows circulation, the upstream discharge oil port and the downstream discharge oil port are provided. A large amount of hydraulic oil is supplied to the hydraulic cylinder by opening the gap with the downstream discharge oil port, and if the flow of hydraulic oil is suppressed, even if the ports are closed, Since the hydraulic oil in the hydraulic cylinder leaks from the gap between the movable rotating body of the variable pulley and the rotating shaft, a small amount of hydraulic oil is discharged from the hydraulic cylinder. As a result, the throttling passage for suppressing the flow of hydraulic oil and the throttling port that communicates with it have been removed, so open and close the throttling port to connect it to the upstream discharge oil port or the downstream discharge oil port. There is no need to provide a spool land portion on the spool valve for switching to either of the two. Therefore, the overall length of the spool valve element can be shortened, and its mass is reduced, so that responsiveness in switching operation of the shift speed control valve device is improved.
Therefore, when duty-controlling the shift speed control valve device, the range in which flow rate can be controlled with respect to changes in duty is expanded, and highly accurate speed ratio control becomes possible. Embodiment Hereinafter, an embodiment of the present invention will be described in detail based on the drawings. In FIG. 1, 10 is a belt-type continuously variable transmission (hereinafter referred to as CVT) which is connected to an automobile engine (not shown) and changes its rotation at a predetermined gear ratio and transmits it to wheels, etc. A hydraulic device 12 for changing (shifting) the gear ratio is provided. On the other hand, the gear ratio controller 14 has
A throttle signal ST representing the engine throttle operation amount from the throttle sensor 16, primary variable pulley rotation sensor 18, secondary variable pulley rotation sensor 20, transaxle oil temperature sensor 22, etc.;
A rotation signal RI representing the rotation speed of the primary variable pulley 24 (engine rotation speed) of the CTV 10, a rotation signal representing the rotation speed of the secondary variable pulley 26
RO, temperature signal indicating transaxle oil temperature
TH etc. are supplied respectively. The gear ratio controller 14 grasps the operating state based on these signals, determines the optimum target gear ratio or target engine rotation speed to obtain the desired operating state, for example, mainly at the minimum fuel efficiency rate, and Drive signals SD1 and SD2 are supplied to the solenoid valves 28 and 30 in the hydraulic system 12, respectively, so that the gear ratio or engine rotation speed matches the target gear ratio or target engine rotation speed. The CVT 10 and hydraulic system 12 are configured as shown in FIG. 2. That is, the CVT 10 has a primary rotation shaft 32 and a secondary rotation shaft 3.
A pair of primary side variable pulley 24 and secondary side variable pulley 26 provided in 4, and those variable pulleys 2
A power transmission belt 36 is provided which is wound between the engine and the primary rotating shaft 32.
The rotational force transmitted to is transmitted to the secondary rotating shaft 34 via the transmission belt 36, and is further transmitted to a differential gear (not shown) via a gear device 38 that can change the direction of rotation such as forward or reverse depending on the shift range. The signal is then transmitted to an output shaft 40 connected to wheels or the like. The primary variable pulley 24 includes a fixed rotating body 42 fixed to the primary rotating shaft 32;
It consists of a movable rotary body 46 that is axially movably but non-rotatably fitted to the primary rotating shaft 32 and is moved in the axial direction by a primary hydraulic cylinder 44, depending on the hydraulic pressure of the primary hydraulic cylinder 44. The groove width of the V groove formed between the fixed rotating body 42 and the movable rotating body 46, that is, the primary variable pulley 24
The effective diameter (the diameter of the transmission belt 36) is changed. Similarly, the secondary variable pulley 26 also has a fixed rotating body 48 fixed to the secondary rotating shaft 34.
and a movable rotary body 52 that is axially movably but non-rotatably fitted to the secondary rotating shaft 34 and is moved in the axial direction by the secondary hydraulic cylinder 50. The width of the V-groove formed between the fixed rotary body 48 and the movable rotary body 52 is changed in accordance with the oil pressure of the rotor 50, thereby changing the effective diameter. Note that the primary side hydraulic cylinder 44 has a double piston structure, so that even if the same line hydraulic pressure is supplied, a larger output than the secondary side hydraulic cylinder 50 can be obtained. The hydraulic system 12 includes a hydraulic system that generates hydraulic oil (line hydraulic pressure) at a predetermined pressure corresponding to a hydraulic signal representing the gear ratio supplied from the sensing valve 54 and a hydraulic signal representing the throttle opening supplied from the throttle valve 66. By supplying line hydraulic pressure to the generator 56 and the primary hydraulic cylinder 44 to increase the pressure, or by allowing discharge of hydraulic oil from the primary hydraulic cylinder 44 and decreasing the pressure,
A shift direction switching valve device 58 that switches the shift direction (speed ratio change direction) and the primary hydraulic cylinder 4
4 or discharged from the primary side hydraulic cylinder 44 to change the shift speed (gear ratio change speed). In addition,
Line hydraulic pressure is always supplied to the secondary side hydraulic cylinder 50 and the sensing valve 54. To further explain the hydraulic system 12 based on FIG. 3, the hydraulic pressure generator 56 includes a pump device 62,
Consisting of a regulator valve 64, a throttle valve 66, a cooler 68, a cooler pressure valve 70, etc., the line oil pressure, which changes depending on the throttle opening and gear ratio, is transferred via a line oil passage 72 to a shift direction switching valve device 58, a shift speed It is designed to be supplied to the control valve device 60, sensing valve 54, etc. The sensing valve 54 includes a spool valve 74 and a movable rotating body 46 of the primary variable pulley 24.
A sensing piston 76 is provided which moves with the belt type continuously variable transmission 10 to apply a biasing force corresponding to the gear ratio of the belt type continuously variable transmission 10 to the spool valve element 74 via a spring. By changing the communication area between the output port 80 and the spool valve 74 responsive to the gear ratio, the gear ratio pressure signal corresponding to the gear ratio shown in FIG.
4 input port 82. The throttle valve 66 includes a spool valve 84,
A piston 90 is provided, which applies a biasing force corresponding to the throttle opening to the spool valve element 84 via a spring 88 by engaging a cam 86 that rotates with the throttle operation and moving with the throttle opening. By adjusting the flow area of the input port 92 communicating with the line oil passage 72, the throttle pressure signal representing the throttle opening shown in FIG. 5 is supplied from the output port 94 to the input port 96 of the regulator valve 64. Ru. The regulator valve 64 has a spool valve 98.
and a valve plunger 100 that receives a gear ratio pressure signal and a throttle pressure signal to control the spool valve element 98, and provides communication between a line port 102 connected to the pump device 62 and a return oil passage 104. By adjusting the area, the line oil pressure of the line oil passage 72 communicating with the line port 102 is adjusted as shown in FIG. In other words, since the hydraulic pressure output from the pump device 62 is generated by the pump 106 driven by the engine, the hydraulic pressure must be at the minimum necessary level to prevent slipping of the transmission belt 36 of the CVT 10 so as not to increase power loss. This pressure is applied to reduce the fuel efficiency of the vehicle. In addition,
The pump device 62 supplies the hydraulic oil returned to the tank 108 from the cooler 68, sensing valve 54, throttle valve 66, shift direction switching valve device 58, shift speed control valve device 60, etc. to the pump 106 through a drain pipe (not shown). The oil is pumped up and supplied to the regulator valve 64 through an oil passage 112 to which a relief valve 110 is attached. The shift switching valve device 58 and the shift direction speed control valve device 60 include electromagnetic valves 28 and 3, respectively.
0 and spool valves 118 and 120, respectively. The line oil pressure is the line oil passage 72.
are supplied to the electromagnetic valves 28 and 30, respectively. The solenoid valve 28 is equipped with an orifice 122 in a passage that communicates with the oil passage 72, and when the solenoid valve 28 is closed (when not energized), the line hydraulic pressure passing through the orifice 122 is applied to the spool valve 118. When applied to the end surface of the spool valve element 124, the spool valve element 124 is moved against the biasing force of the spring 126, as shown on the right side with respect to the center line CS in FIG. B state), but the solenoid valve 2
The orifice 12 is opened by the opening operation (at the time of excitation) of 8.
When the action of the line hydraulic pressure on the spool valve element 124 is released by discharging the pressure downstream from 2,
As shown on the left side of center line CS, spool valve 1
24 is moved according to the urging force of the spring 126 (hereinafter referred to as the A state). That is, the spool valve element 124 is moved to the second position in response to the operation of the solenoid valve 28, and the B
In the state, the line oil passage 72 and the supply passage 12
8 is connected, while the discharge passage 130 is blocked and line hydraulic pressure is allowed to be supplied to the primary hydraulic cylinder 44, increasing the pressure within the primary hydraulic cylinder 44. However, in state A, the oil passage 72 While the supply passage 128 and the supply passage 128 are cut off,
The discharge passage 130 is opened to the drain pipe line 131, and the supply of line supply hydraulic pressure to the primary hydraulic cylinder 44 is blocked, and the pressure within the primary hydraulic cylinder 44 is reduced. Here, the spool valve 124 is connected to the spool shaft 13.
2 and a plurality of spool land portions 134A, 134B partially formed with a large diameter in the axial direction.
134S, and is slidably fitted into a cylinder bore 138 formed in the valve body 136, and when the spool valve element 124 is in the B state, the spool land portion 134B is connected to the line oil passage 7.
2 and open into the cylinder bore 138, and when the spool valve 124 is in the A state, the spool land portion 134A is connected to the discharge passage 13.
0 and opens into the cylinder bore 138. Note that the throttle 140 provided between the line oil passage 72 and the spool valve 118 sets the maximum flow rate of the hydraulic oil supplied to the hydraulic cylinder 44. On the other hand, the solenoid valve 30 is also equipped with an orifice 142, and like the solenoid valve 30, when the solenoid valve 30 is closed (de-energized), the spool valve 120 is spool valve 14
The spool valve 144 is moved against the biasing force of the spring 146 (hereinafter referred to as state B) by applying line hydraulic pressure through the orifice 142 to the end face of the spool valve 144, but when it is released, the center line Spool valve 144 as shown on the left side of CH
The action of the line hydraulic pressure is released and the spool valve element 144 is moved according to the biasing force of the spring 146 (hereinafter referred to as the A state). The spool valve 120 is equipped with a downstream supply port 148 and an upstream discharge port 150 that communicate with the primary hydraulic cylinder 44, and an upstream supply port 152 and a downstream discharge port that are connected to the supply passage 128 and the discharge passage 130, respectively. A side discharge port 154 is provided, and when the spool valve element 144 is brought into the B state by the closing operation (when not energized) of the solenoid valve 30, a downstream side supply port 148 and an upstream side supply port 152 are provided. The upstream discharge port 150 and the downstream discharge port 154 are communicated with each other. Also,
When the spool valve 144 is placed in the A state according to the opening operation (at the time of excitation) of the solenoid valve 30, the upstream discharge port 150 and the downstream discharge port 154 are cut off, and the upstream supply port 15
2 and the downstream supply port 148 are communicated with each other. Here, the spool valve 144 has a throttle passage 15.
6 is formed, and even if the spool valve 144 is in the B state, the throttle passage 15 is formed between the upstream supply port 152 and the downstream supply port 148.
Hydraulic oil is allowed to flow through 6. The flow rate of the hydraulic oil is set to be equal to or lower than the leakage rate from the hydraulic cylinder 44, for example. Further, the spool valve 144 is connected to the spool shaft 15.
8 and spool land portions 160A, 160B, 160 partially formed with large diameters in the axial direction.
C, 160D, and are slidably fitted into a cylinder bore 159' formed in the valve body 159, and when the spool valve element 144 changes from state A to state B, the spool land portion 160B discharges the upstream side. The spool land portion 160A passes through the downstream supply port 148 and opens it when the spool valve 144 returns to the A state. When the spool valve element 144 is in the A state, the upstream discharge port 150 and the downstream discharge port 154 are cut off, but the gap 159 provided between the movable rotating body 46 and the primary rotating shaft 32, etc. By discharging the hydraulic fluid, a small amount of hydraulic fluid is discharged from the hydraulic cylinder 44. Therefore, in the spool valve 120 for switching the shift speed, since the throttle passage for suppressing the flow of hydraulic oil during discharge and the throttle port communicating with the passage are removed, the throttle port can be switched. This eliminates the need for a spool land portion, and the overall length of the spool valve 144 is short and lightweight. In addition, the hydraulic cylinder 44 and the upstream discharge port 1
The throttle 162 provided in the discharge passage 161 on the upstream side between the hydraulic cylinder 44 and the hydraulic cylinder 44 is for setting the maximum flow rate of the hydraulic oil discharged from the hydraulic cylinder 44 . Further, in the solenoid valves 28 and 30, spool valves 118 and 120 are located on the left and right of the center line.
The operating states corresponding to the operating positions shown to the left and right of the center lines CS and CH are shown. In the hydraulic system 12 configured as described above, for example, the present applicant has previously filed a patent application filed in 1983-
The hydraulic control method described in the specification of No. 203130 is the first
It is carried out as shown in the table. That is, when the CVT 10 is to be upshifted rapidly, the drive signal SD1 that de-energizes the solenoid valve 28 is output from the gear ratio controller 14, and the spool valve 124 of the shift direction switching valve device 58 is brought into the B state. At the same time, a drive signal SD2 for energizing the solenoid valve 30 is output from the gear ratio controller 14 and the shift speed control valve device 6 is outputted from the gear ratio controller 14.
The spool valve 144 of 0 is placed in the A state. For this reason, as shown in FSmax in FIG. 7, the hydraulic oil in the line oil passage 72 is
Upstream supply port 152, downstream supply port 14
8 and is supplied to the hydraulic cylinder 44 in large quantities, and the effective diameter of the primary variable pulley 24 is rapidly increased, and the effective diameter of the secondary variable pulley 26 is rapidly decreased. As a result, the gear ratio of CVT10 is adjusted.

[Table] Can be rapidly changed in the direction of push shift. Here, the excitation state of the solenoid valve 30 means its duty.
Corresponds to 100% condition. In the above upshift state, when slowly upshifting with the shift speed (speed ratio change speed) set to the minimum, the drive signal SD2 that de-energizes the solenoid valve 30 is output from the speed ratio controller 14, so that the shift speed control valve The spool valve 144 in the device 60 is in the B state. Therefore, the hydraulic oil supplied from the line oil passage 72 to the hydraulic cylinder 44 passes through the throttle passage 156 formed in the spool valve element 144, as shown in FIG.
As shown by FSmin, the amount of hydraulic oil supplied to the hydraulic cylinder 44 is significantly suppressed. As a result,
The speed at which the gear ratio changes in the upshift direction of the CVT 10 is significantly slowed down. Here, the non-excited state of the solenoid valve 30 corresponds to a state where its duty is 0%. In the above-mentioned upshift state, if the speed ratio change speed is desired to be an intermediate shift speed between the above two states, the pulse-shaped drive signal SD2 for energizing the solenoid valve 30 at a predetermined period is used to shift the gear ratio. It is supplied from the ratio controller 14, and the spool valve element 144 of the shift speed control valve device 60 is periodically positioned between the A state and the B state with a predetermined duty. Therefore, as shown in FIG. 7, the flow rate of hydraulic oil supplied to the hydraulic cylinder 44 is reduced by
It is continuously controlled by changing the duty of 0. On the other hand, when it is desired to rapidly downshift the CVT 10, the drive signal SD1 that turns the solenoid valve 28 into an excited state is output from the gear ratio controller 14, and the spool valve 124 in the shift direction switching valve device 58 is set to the A state. At the same time, the solenoid valve 30
A drive signal SD2 that de-energizes is outputted from the speed ratio controller 14, and the spool valve element 144 of the shift speed control valve device 60 is brought into the B state. Therefore, as shown in FDmax in Figure 8,
The hydraulic oil in the hydraulic cylinder 44 is supplied to the throttle 162 through an upstream discharge port 150 and a downstream discharge port 15.
4. It is rapidly discharged through the discharge passage 130 and the drain pipe line 131, and the effective diameter of the primary variable pulley 24 is rapidly reduced, and the effective diameter of the secondary variable pulley 26 is rapidly increased. As a result, the CVT 10 is rapidly shifted in the downshift direction. On the other hand, in the case of a slow downshift, a drive signal SD2 for energizing the solenoid valve 30 is output from the gear ratio controller 14,
The spool valve 144 in the shift speed control valve device 60 is placed in the A state. Therefore, the space between the upstream discharge port 150 and the downstream discharge port 154 is closed by the spool land portion 160B, but as shown at FDmin in FIG. A small amount of hydraulic oil in the hydraulic cylinder 44 leaks from the gap 159 between the two, so that the effective diameter of the primary variable pulley 24 is gradually reduced, and the CVT 10 is slowly downshifted. In the downshift state as described above, when the shift speed is set to an intermediate speed between the above two states, the pulsed drive signal SD2 for energizing the solenoid valve 30 at a predetermined period is transmitted to the gear ratio controller 14. output from the shift speed control valve device 6
0 spool valve 144 is repeatedly positioned in the A state and the B state. As a result, as the duty of the electromagnetic valve 30 is continuously changed as shown by the solid line in FIG. 8, the discharge flow rate of the hydraulic oil from the hydraulic cylinder 44 is continuously controlled. As described above, when the CVT 10 is upshifted and downshifted, the supply flow rate of hydraulic oil supplied to the hydraulic cylinder 44 or the discharge flow rate of hydraulic oil discharged from the hydraulic cylinder 44 is continuously controlled, so that, for example, This allows the actual engine speed to match the target engine speed. Here, in the shift speed control valve device 60, as described above, since the throttle passage for suppressing the flow of hydraulic oil during discharge and the throttle port communicating therewith are removed, the throttle port is Upstream discharge port 150 or downstream discharge port 15
A spool land portion for switching to communicate with the spool valve 144 is no longer necessary, and the overall length of the spool valve 144 is shortened. Therefore, since the spool valve element 144 is lightweight, high responsiveness of the switching operation in the shift speed control valve device 60 can be obtained, and in the duty control of repeatedly operating the solenoid valve 30, the region where the flow rate can be controlled with respect to changes in duty is the first. 7
As shown in Figure 8 and CWS and CWD, the conventional width CWS' and CWD where the port is fully opened are shown.
Since it is significantly expanded compared to CWD', fine and highly accurate control is possible. Further, according to this embodiment, the spool valve 144
As a result, the overall length of the shift speed control valve device 60 is reduced in size, and the weight and manufacturing cost are reduced. Although one embodiment of the present invention has been described above in detail based on the drawings, the present invention can also be applied to other aspects. For example, each valve 64, 66, 5 in FIG.
Some or all of 8, 60, etc. may be provided within a common housing. Further, in the above embodiment, the shift speed control valve device 60 and the shift direction switching valve device 58 may be connected interchangeably. Furthermore, as shown in FIG. 9, the spool valve 120 of the shift speed control valve device 60 may be divided into spool valves 120S and 120D for controlling the flow rate of hydraulic fluid on the supply side and the discharge side. According to this embodiment, the spool valves 120S and 12
The overall length of the 0D spool valves 144S and 144D can be made shorter and lighter, with the advantage of higher responsiveness. In this case, a solenoid valve for driving the spool valves 144S and 144D may be provided for each of the spool valves 120S and 120D. Additionally, in the embodiments described above, the supply passage 128
The spool valves 120S and 1
20D may be inserted. The above-mentioned embodiment is merely one embodiment of the present invention, and various modifications may be made to the present invention without departing from the spirit thereof.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram illustrating a hydraulic system for a belt-type continuously variable transmission and its control system to which the present invention is applied. FIG. 2 is a diagram illustrating the main part of FIG. 1. FIG. 3 is a sectional view of a main part for explaining in more detail the structure of the hydraulic system shown in FIGS. 1 and 2. FIG. FIG. 4 is a diagram showing the relationship between the gear ratio pressure signal output from the sensing valve of FIG. 3 and the amount of movement of the movable rotating body. FIG. 5 is a diagram showing the relationship between the throttle pressure signal output from the throttle valve of FIG. 3 and the throttle opening degree. FIG. 6 is a diagram showing the relationship between the line oil pressure adjusted by the regulator valve of FIG. 3 and the throttle opening. 7th
FIG. 8 and FIG. 8 are diagrams showing the change characteristics of the supply flow rate or the discharge flow rate with respect to changes in the duty of the signal that drives the electromagnetic valve in the shift speed control valve device of FIG. 3, respectively. FIG. 9 is a diagram showing essential parts of another embodiment of the present invention. 10: Belt type continuously variable transmission (CVT), 12: Hydraulic system, 24: Primary side variable pulley, 26: Secondary side variable pulley} (variable pulley), 36: Transmission belt,
44: (Primary side) hydraulic cylinder, 46, 52: Movable rotating body, 56: Hydraulic pressure generator, 58: Shift direction switching valve device, 60: Shift speed control valve device, 1
28: Supply passage, 130, 161: Discharge passage, 1
44: Spool valve, 150: Upstream discharge port, 154: Downstream discharge port, 156: Throttle passage, 160A, 160B, 160C, 160D:
Spool land department.

Claims (1)

[Claims] 1. A first switching state in which hydraulic oil is supplied through a supply passage to a hydraulic cylinder for changing the effective diameter of a pair of variable pulleys provided in a belt type continuously variable transmission, and a first switching state in which hydraulic oil is supplied through a supply passage to a hydraulic cylinder for changing the effective diameter of a pair of variable pulleys provided in a belt type continuously variable transmission; A shift direction switching valve device is provided that can be selectively switched to a second switching state that allows discharge of hydraulic fluid, and the direction of change in the gear ratio of the belt type continuously variable transmission is controlled by switching the shift direction switching valve device. In a hydraulic system for a belt-type continuously variable transmission to be controlled, the hydraulic system is inserted into the supply passage and the discharge passage, and is periodically switched between two operating states: a state in which the flow of the supply passage or the discharge passage is suppressed and a state in which the flow is permitted. A spool valve-type shift speed control valve device that continuously controls the speed of change of the gear ratio by being switched and changing the time ratio of the two operating states, wherein the hydraulic oil from within the hydraulic cylinder As ports involved in the discharge, only an upstream discharge oil port and a downstream discharge oil port are provided, which communicate with the upstream and downstream sides of the discharge passage, respectively, and in the permissible state, the upstream discharge oil port and the downstream side discharge oil port is opened, and in the suppressed state, the space between the upstream side discharge oil port and the downstream side discharge oil port is controlled to be closed. A shift speed control valve device for a hydraulic system for a belt-type continuously variable transmission.