JPH0621637B2 - Belt type continuously variable transmission hydraulic system - Google Patents

Description

TECHNICAL FIELD The present invention relates to a hydraulic device for a belt type continuously variable transmission, and more particularly to a technique for improving speed ratio control of a belt type continuously variable transmission.

2. Description of the Related Art A primary side rotating shaft and a secondary side rotating shaft, a pair of variable pulleys with variable effective diameters respectively provided on the primary side rotating shaft and the secondary side rotating shaft, and at least one of the pair of variable pulleys. In a belt type continuously variable transmission including a hydraulic cylinder that changes the effective diameter and a transmission belt that is wound around the variable pulley, a hydraulic oil inflow amount that is made to flow into the hydraulic cylinder from a hydraulic source, or from the hydraulic cylinder. 2. Description of the Related Art There is known a hydraulic device that adjusts a discharge amount of hydraulic oil to be discharged by a flow rate control valve device to change a speed ratio of a primary side rotating shaft and a secondary side rotating shaft. Such a hydraulic system provides high fuel consumption efficiency and drivability when, for example, a belt type continuously variable transmission is installed in a vehicle for continuously changing the output of the engine and transmitting the output to the drive wheels. It is used to control the speed ratio so that the target rotation speed that is sequentially determined as described above and the rotation speed of the engine match.

Problems to be Solved by the Invention However, in the flow rate control valve device used in the conventional hydraulic device, a relatively large clearance is set in the operating portion in order to operate stably even if foreign matter is present in the hydraulic oil, Even when the flow rate control valve device is fully closed, it is common for hydraulic fluid to flow from the hydraulic source to the hydraulic cylinder or to leak from the hydraulic cylinder via the flow rate control valve device. In addition, some hydraulic oil may leak from the hydraulic cylinder. It is common that the amount of hydraulic oil leaked from such a hydraulic cylinder and the leakage flow rate flowing into the hydraulic cylinder from the hydraulic source via the flow rate control valve device are different from each other. When trying to control the speed ratio of the belt type continuously variable transmission, the speed ratio corresponding to the operating state of the flow rate control valve device cannot be obtained, and the actual speed ratio is controlled to a value deviating from that. That is, there is a disadvantage that a control deviation (steady deviation) occurs in the speed ratio.

Means for Solving the Problems The present invention has been made in view of the above circumstances, and its gist is to provide the flow rate control valve device between the hydraulic power source and the hydraulic cylinder. A compensating oil passage is provided in a state of being externally bypassed, and the amount of hydraulic oil in the hydraulic cylinder is reduced due to hydraulic oil leakage when the flow control valve device prevents the hydraulic oil from flowing into and out of the hydraulic cylinder. The reason is that the compensating oil passage is provided with a throttle that is set so as to allow a corresponding flow rate of hydraulic oil to flow into the hydraulic cylinder.

With this configuration, the compensating oil passage provided between the hydraulic power source and the hydraulic cylinder in a state where the flow rate control valve is externally bypassed, and the throttle provided in the compensating oil passage. , Since a flow rate of hydraulic oil corresponding to the amount of hydraulic oil reduction in the hydraulic cylinder is made to flow in, a speed ratio that faithfully responds to the operating state of the flow rate control valve device can be obtained, and the control deviation in speed ratio control is suitably eliminated. Is done.

Further, since the compensating oil passage is provided outside the flow rate control valve device and does not require delicate processing inside the flow rate control valve device, the operation is stable and the structure of the flow rate control valve device is complicated. Therefore, the manufacturing cost of the hydraulic device does not increase.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

In FIG. 1, the primary rotary shaft 12 and the secondary rotary shaft 14 of the belt type continuously variable transmission 10 are provided with variable pulleys 16 and 18 having variable effective diameters. The variable pulleys 16 and 18 are fixed rotating bodies 20 and 22 fixed to the primary side rotating shaft 12 and the secondary side rotating shaft 14, respectively.
And movable rotating bodies 24 and 26 provided on the primary-side rotating shaft 12 and the secondary-side rotating shaft 14 such that they cannot rotate about their axes and are movable in the axial direction, respectively.
0 and the movable rotary body 24 and between the fixed rotary body 22 and the movable rotary body 26 in the V groove formed.
Is wound around, and the rotation of the primary side rotating shaft 12 is transmitted to the secondary side rotating shaft 14. Movable rotating body 2
4 and 26 are hydraulic cylinders 30 and 32, respectively.
Is driven by the hydraulic cylinder 3
0 drives the movable rotating body 24 to exclusively adjust the speed ratio of the primary side rotating shaft and the secondary side rotating shaft 14 of the belt type continuously variable transmission 10. Further, the hydraulic cylinder 32 drives the movable rotating body 26 to exclusively adjust the clamping force against the transmission belt 28, in other words, the tension of the transmission belt 28.

On the other hand, a hydraulic pump 34, which is connected to an engine of a vehicle (not shown), transfers the hydraulic oil in an oil tank 36 to a hydraulic cylinder 32 and an inflow port 42 of a speed ratio control valve 40 as a flow rate control valve device via a line oil passage 38. Supply. The electromagnetic relief valve 44 adjusts the escape amount of the working oil in the line oil passage 38 according to a line pressure command signal from a controller (computer) not shown, and transmits the working oil pressure in the line oil passage 38 to the primary side rotating shaft 12. The power loss is controlled as small as possible by controlling the hydraulic pressure to the minimum hydraulic pressure determined based on the output torque of the engine and the speed ratio of the belt type continuously variable transmission 10 within a range in which the transmission belt 28 does not slip. To do.

The speed ratio control valve 40 is a linear solenoid type three-port three-position switching valve. When the speed ratio command signal from the controller is supplied to the solenoid 46, the inflow port 42 and the output port 48 communicate with each other. The hydraulic cylinder 30 connected to the output port 48 is supplied with hydraulic oil in an amount according to the magnitude of the speed ratio command signal. When the speed ratio command signal from the controller is supplied to the solenoid 50, the output port 48 and the outflow port 52 are communicated with each other, and the hydraulic cylinder 30 supplies hydraulic oil in an amount corresponding to the magnitude of the speed ratio command signal. The return oil passage 54 is discharged. And
When the speed ratio command signal is not supplied to any of the solenoids 46, the outflow port 52 and the inflow port 42 are disconnected from the output port 48, and the hydraulic cylinder 30
The discharge of the hydraulic oil therein or the inflow of the hydraulic oil into the hydraulic cylinder 30 is substantially blocked, and the speed ratio of the belt type continuously variable transmission 10 is fixed.

The speed ratio control valve 40 is constructed, for example, as shown in FIG. That is, the inflow port 42 and the output port 4
8. The main body 56 in which the outflow port 52 is formed has a pair of cylindrical members 62, 6 having flanges 58, 60, respectively.
4 is fixed in a symmetrical position, and its cylindrical members 62, 6
Valves 66 and 68 are slidably fitted in the unit 4.
The valve elements 66, 68 are constantly abutted against the annular abutting members 74, 76 by being biased by the springs 70, 72, respectively, but when the solenoids 46, 50 are excited. Spring 70,
72 is moved against 72, and the solenoid 46, 50 is positioned at a position where the driving force by the solenoid 46, 50 and the biasing force by the spring 70, 72 are balanced.
When the driving force of 50 increases, the cylindrical member 62,
It is moved to a position where it abuts against stoppers 78 and 80 which are formed stepwise in 64.

Since the valves 66 and 68 have the same structure,
The valve 66 will be described below. As shown in detail in FIG. 3, the valve element 66 has four notches 82 from its cylindrical end.
Is cut parallel to the axis, and when the valve element 66 is in contact with the contact member 74, the notch and the inner opening 86 of the passage 84 formed in the cylindrical member 62 communicate with the inflow port 42. 82 is a small constant distance D in the axial direction.
However, the valve element 66 is separated by the spring 70.
The inner opening 8 of the passage 84 as it is moved against
6 and the notch 82 overlap each other to increase the flow area, so that the output port 48 and the inflow port 42 can communicate with each other. FIG. 4 shows the characteristic of the speed ratio control valve 40.

By the way, the speed ratio control valve 40 is slidably fitted to the cylindrical members 62 and 64 so that the speed ratio control valve 40 can operate stably even with respect to foreign substances which are expected to be mixed in the hydraulic oil. A predetermined clearance C is generally formed between the valve elements 66, 68 that have been opened, and the relatively high pressure hydraulic oil in the line oil path 38 passes through the clearance C to the output port 48. It is possible to prevent the hydraulic oil from flowing into the hydraulic cylinder 30 connected via 53, or the hydraulic oil on the output port 48 side having a relatively high pressure with respect to the return oil passage 54 from leaking to the outflow port 52 through the clearance C. Absent. Further, in the hydraulic cylinder 30, the primary side rotating shaft 12 and the members fixed thereto, and the primary side rotating shaft 12
In many cases, the hydraulic oil in the hydraulic cylinder 30 leaks out from between the movable rotary body 24 slidably attached to the member fixed thereto and in the axial direction. Further, in order to positively lubricate the transmission belt 28, the hydraulic oil in the hydraulic cylinder 30 may be positively leaked from the central portion of the movable rotary body 24. Q1 in FIGS. 1 and 4 indicates the speed ratio control valve 40 from the line oil passage 38 to the hydraulic cylinder 30.
Shows the flow rate leaking to the side, and Q2 shows the flow rate leaking from the output port 48 (hydraulic cylinder 30) side to the outflow port 52 side in the speed ratio control valve 40. Further, Q3 in FIG. 1 shows the flow rate that leaks directly from the hydraulic cylinder 30 to the outside.
Since the flow rate Q1 is generally smaller than the flow rate (Q2 + Q3), even if a controller (not shown) actuates the speed ratio control valve 40 to obtain a desired speed ratio, the speed ratio is deviated. . Therefore, in order to maintain the speed ratio, the controller must slightly excite the solenoid 46 to continue operating the speed ratio control valve 40. As a result, when the operation amount of the speed ratio control valve 40 is zero (when the valve elements 66, 68 are in contact with the contact members 74, 76), the speed ratio changes, and the speed ratio is changed by a slight operation. Since it will be maintained constant, a control deviation (steady-state deviation) will occur in the speed ratio control.

On the other hand, according to the present embodiment, as shown in FIG. 1, a bypass passage 90 having a throttle valve 88 is connected between the line oil passage 38 and the oil passage 53, which are hydraulic pressure sources. The difference between the inflow amount Q1 and the outflow amount (Q2 + Q3) due to the leakage is compensated, and the speed ratio is maintained even when the speed ratio control valve 40 is in the non-operating state (neutral state).
That is, the throttle valve 88 changes the flow rate in the bypass passage 90 by Δ.
It is set such that Q {= (Q2 + Q3) -Q1}, and the amount of hydraulic oil in the hydraulic cylinder 30 does not fluctuate even if the leak amounts Q1, Q2, Q3 exist.

Thus, according to this embodiment, the flow rates Q1, Q2, Q3
Even if there are leaks represented by, the amount of oil corresponding to the fluctuation (decrease) in the flow rate on the hydraulic cylinder 30 side due to such leaks is passed through the bypass passage 90 to the hydraulic cylinder 30.
Is supplied to the hydraulic cylinder 30, the amount of hydraulic oil in the hydraulic cylinder 30 is maintained constant. Therefore, the speed ratio faithfully responding to the speed ratio command signal supplied to the speed ratio control valve 40 can be accurately obtained, and the control deviation (steady deviation) can be almost eliminated.

Further, according to the present embodiment, since the delicate machining inside the speed ratio control valve 40 is not required, the operation becomes stable, and the structure of the speed ratio control valve 40 does not become complicated, so that the manufacturing cost of the hydraulic device is reduced. Does not increase.

The speed ratio control valve 40 can take various forms in its on-off valve mechanism and overall structure, and may be composed of, for example, two flow rate control valves each provided with a solenoid. Further, the opening / closing mechanism may be configured such that the valve element is driven by a pilot method, or the valve element is opened and closed by being seated on the belt seat. The speed ratio control valve 40 is not only a linear solenoid type valve but also an ON-OFF type valve whose valve element is located at two positions, an open position and a closed position, and is duty controlled by a control signal from the controller. It may be a model. Further, the hydraulic cylinder 32 may be used for speed ratio control.

The above description is merely one embodiment of the present invention, and the present invention can be variously modified without departing from the spirit thereof.

[Brief description of drawings]

FIG. 1 is a diagram showing the configuration of a hydraulic system according to an embodiment of the present invention. FIG. 2 is a sectional view showing a structural example of the speed ratio control valve used in FIG. FIG. 3 is a sectional view showing an essential part of the speed ratio control valve of FIG. FIG. 4 is a characteristic diagram of the speed ratio control valve of FIG. 10: Belt type continuously variable transmission 12: Primary side rotating shaft, 14: Secondary side rotating shaft 16, 18: Variable pulley, 30: Hydraulic cylinder 40: Speed ratio control valve (flow rate control valve device) 88: Throttle valve ( Throttle) 90: Bypass passage (compensation oil passage)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mikio Suzuki 1-1, Asahi-cho, Kariya city, Aichi Toyota Koki Co., Ltd. (72) Inventor Masaaki Hayashi 1-1-chome, Asahi-cho, Kariya city, Aichi Toyota Koki Within the corporation (56) References Japanese Patent Laid-Open No. 58-57553 (JP, A)

Claims (1)

[Claims] 1. A primary-side rotating shaft and a secondary-side rotating shaft, a pair of variable pulleys provided on the primary-side rotating shaft and the secondary-side rotating shaft, each having a variable effective diameter, and a pair of the variable pulleys. A hydraulic cylinder for changing at least one of the effective diameters,
In a belt type continuously variable transmission including a transmission belt wound around the variable pulley, a flow rate of an inflow amount of hydraulic oil flowing from a hydraulic pressure source to the hydraulic cylinder or a discharge amount of hydraulic oil discharged from the hydraulic cylinder. A hydraulic device for adjusting the speed ratio of the primary side rotary shaft and the secondary side rotary shaft by adjusting with a control valve device, wherein the flow rate control valve device is externally provided between the hydraulic power source and the hydraulic cylinder. Provide a compensating oil passage in a bypassed state,
In addition, a hydraulic fluid having a flow rate corresponding to a hydraulic oil reduction amount in the hydraulic cylinder caused by the hydraulic oil leak when the flow control valve device blocks the inflow and discharge of the hydraulic oil to the hydraulic cylinder is supplied to the hydraulic cylinder. A hydraulic device for a belt-type continuously variable transmission, characterized in that a throttle set to allow inflow is provided in the compensating oil passage.