JPS591356B2 - Pump device with continuously variable transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pump device that is connected to an engine rotating shaft via a continuously variable transmission. The purpose is to stabilize the pump flow rate characteristics when the load on the pump device is reduced.

Conventionally, various flow control methods have been considered in order to maintain a constant flow rate supplied from a pump connected to the engine rotating shaft to a power steering device, etc.・The disadvantage of the flow control valve method is that the pump consumes a large amount of power.

For this reason, the pump speed/weight system, which allows the pump to discharge only a certain amount of fluid as required, has been attracting attention as being preferable from the standpoint of reducing power consumption.

In this pump speed weighting system, the pump is connected to the engine rotating shaft via a continuously variable transmission, and a restriction is provided in the fluid delivery path of the pump to keep the pump speed constant, and the pressure difference before and after the restriction is There is a device that automatically controls the speed change mechanism of a continuously variable transmission in order to maintain a constant value. and a pressure responsive device connected to the transmission mechanism.

In a pump device having such a configuration, when a high load is applied, for example, if the bundle is turned off during steering resistance such that the piston of the power steering device that receives fluid supply from the pump device cannot move, the power steering device Continuous flow of fluid through the device is interrupted.

In this state where the continuous flow of fluid is interrupted, the discharge pressure of the pump suddenly increases, so the pressure must be controlled so that it does not exceed a preset pressure.

However, in such a pump device equipped with a continuously variable transmission, if there is no continuous flow of fluid, the pressure difference before and after the throttle disappears, and the transmission mechanism is controlled to change the gear ratio to prevent pressure rise. It acts on

However, when the bundle is returned, the load is reduced and continuous flow through the power steering system is immediately provided, causing the transmission mechanism to operate in the opposite direction to restore the transmission ratio to its original state; The flow rate changes greatly due to delays, etc.

However, even at high loads where continuous flow is interrupted, if only the pressure is released and the gear ratio is not changed, such instability of the custom flow rate can be avoided.

In view of the above points, the present invention has been developed to throttle and pass through a pressure relief valve in order to create a constant pressure difference before and after the throttle even when a high load is applied, in order to stabilize the flow rate characteristics when the pump device is released from a high load. This pressure relief valve is installed in the rear fluid delivery path, and when the load is high, the entire amount of pump discharge flow is released from this pressure relief valve, keeping the pressure difference before and after the throttle constant, preventing the gear ratio from changing, and releasing pressure. It is.

This will be explained below using examples.

FIG. 1 shows the operating principle of the present invention, where 1 is an engine, 2 is a continuously variable transmission, and 3 is a pump.

The continuously variable transmission 2 is coaxially connected to the pump 3. The driven shaft 2b of the continuously variable transmission 2 is connected to the pump rotating shaft 3a, and the driving shaft 2a of the continuously variable transmission 2 is connected to the pulley 5. is fixed to the engine rotating shaft 6, and connected by a belt 8 to a pulley 7 fixed to the engine rotating shaft 6.

The pump 3 is a constant displacement pump, and a discharge fluid delivery path 10 of the pump 3 is communicated with a power steering device 18.

A throttle 11 is provided in the middle of this fluid delivery path 10, and a pressure relief valve 16 is provided in the delivery path 10 after passing through this restriction 11.

Fluid pressure before and after the throttle 11 is introduced into the left and right chambers 12a and 12b of the cylinder 12.

The piston rod 13 of the cylinder 12 is connected to the continuously variable transmission 2.
The transmission mechanism is operatively connected to the transmission mechanism, and the transmission ratio is controlled by the pressure difference generated before and after the throttle 11.

A spring 14 inserted into the low-pressure side chamber 12b of the cylinder 12 is used to apply a pressing force to the transmission mechanism in the direction of increasing the rotation of the driven shaft relative to the rotation of the driving shaft of the continuously variable transmission 2.

Note that this spring 14 does not necessarily have to be provided inside the cylinder.

If the spring constant of this spring 14 is K, then the amount of deflection δ
The spring force F at this time becomes δ in F=.

On the other hand, if the fluid pressures before and after the throttle 11 are Pl and P2, and the left and right effective areas of the piston 15 are S, then 5 (Pl - P2)
-F, the pressing force acting on the piston is balanced.

At this time, if a pressure difference △P is generated before and after the throttle 11, then the pressure difference △P is proportional to the deflection amount δ of the spring 14, the piston 15 causes a displacement amount δ, and this displacement amount of the piston 15 δ operates the transmission mechanism to automatically control the transmission ratio in order to keep the pressure difference before and after the throttle 11 substantially constant.

As a result, if the opening degree of the throttle 11 is kept constant, the flow rate that passes through the throttle 11 and is sent to the delivery path 10 is kept approximately constant.

In other words, such speed ratio control of the continuously variable transmission 2 is a speed change control that keeps the pump rotational speed almost constant in response to changes in the rotational speed of the engine 1, and the pump 3 outputs an almost constant amount. Fluid will be discharged.

By the way, when the power steering device 18 is under a high load, the continuous flow of fluid is cut off, so the pressure in the fluid delivery path 10 increases, and when the pressure within the fluid delivery path 10 exceeds the set pressure of the pressure relief valve 16, this pressure relief valve 16 is opened. Fluid is discharged to the pump suction side, that is, to the oil tank.

As a result, the flow rate passing through the throttle 11 is maintained in the same state as before the high load action, and the pressure difference before and after the throttle 11 is also kept constant.

Therefore, the pressure response device 12 does not operate and the gear ratio of the continuously variable transmission 2 does not change, so the pump discharges a constant amount of fluid, and when the load on the power steering device 18 is reduced, the continuous flow of fluid resumes. As such, closing of the pressure relief valve 16 alone achieves the constant amount of fluid supply required by the power steering system 18.

Next, a specific example of the present invention based on the operating principle shown in FIG. 1 will be explained with reference to FIG.

The pump body 20 is concentrically formed with an enlarged inner hole 21 for accommodating the continuously variable transmission T and an inner hole 22 for accommodating the pump component P.

The enlarged inner hole 21 includes a pair of rotating friction plates 23 and 24 coaxially arranged facing each other, and a rolling surface 2 of both friction plates 23 and 24.
3a, a ball 25 that rolls in contact with 24a, a holding roller 26 that holds the ball 25 in a movable manner and tilts its axis of rotation in a plane passing through the transmission axis, and a rotational support for the holding roller 26. A holding case 27 that swingably holds the shaft 26a via a cage 26b is housed.

A driving shaft 28 protruding from the rotating friction plate 23 is connected to the pump body 2.
A driven shaft 31 is supported by a lid member 29 fixed to one end surface of the pump assembly P through a bearing 30 so as to prevent displacement only in the axial direction. 22 and is supported by the pump body 20 via a bearing 32, and is allowed to move in the axial direction together with the bearing 32.

A pulley 5 is fixed to one end of the driving shaft 28, and the pulley 5 is driven by a pulley 7 provided on the engine rotating shaft 6 via a belt 8.

A hollow inner hole 33 is bored through the driven shaft 31, and a spline 34 is carved on the outer peripheral surface.

The inner hole 22 has a cam ring 40 forming a pump casing and a pump rotor 42 having a plurality of vanes 41 in sliding contact with the inner circumferential surface 40a of the cam ring 40 and movable in the radial direction in the center and in contact with both end surfaces thereof. A pump assembly P formed by laminating side plates 43 and 44 is housed, and a lid body 45 that closes the open end of the inner hole 22 is housed with a spring 46 interposed between the side plate 44 and the side plate 44. , is prevented from coming off by a retaining ring 47.

A cylinder 48 into which a piston 49 is fitted is formed concentrically with the pump rotor 42 at the center of the lid body 45.
The open end of cylinder 48 communicates with pressure chamber 67 .

The piston 49 is connected to one end of a rod 53 that passes through the hollow inner hole 33 of the driven shaft 31 and is supported by bearing bushes 51 and 52 to allow rotation and axial movement.

The other end of the rod 53 is inserted into the holding case 27,
A hook having an engaging portion 54a that engages with a pin 26c drilled in the cage 26b is connected to the member 54, and a spring 55 that presses the member 54 to the right in the figure is interposed between the hook and the holding case 27. equipped.

An oil tank 60 is fixed above the pump body 20, and a cylindrical protrusion 61 provided at the bottom of the oil tank is fitted into a vertical hole 62 of the pump body 20, and an annular flow path 63 formed around the cam ring 40 is connected to the oil tank 60. A suction passageway leading to the pump suction area is formed through the pump.

An arcuate groove 65 and an arcuate through hole 66 are formed in the side plates 43 and 44 in correspondence with the pump discharge area.
It communicates with a pressure chamber 67 formed between the four lids 45, and also communicates with a chamber between the pump body 20 and the side plate 43 through a passage 81.

As shown in FIG. 6, the fluid discharged into the pressure chamber 67 communicates with a discharge passage 68 bored in the pump body 20 via a throttle 70, and is supplied to a power steering device etc. through a discharge port 69. Ru.

The pressure fluid before and after the throttle 70, that is, the pressure fluid in the pressure chamber 67, is introduced into the right chamber of the piston of the cylinder 48, and the pressure fluid in the delivery path 68 after passing through the throttle and 70 flows through the passages 72 and 73 into the cylinder 48. Introduced into the left chamber of the piston, a pressing force corresponding to the pressure difference between the two river force fluids acts on the piston 49,
The hook displaces the member 54 in the axial direction against the spring 55 via the rod 53, and rotates the support shaft 2 of the holding roller 26.
6a is oscillated relative to the holding case 27.

As a result, as shown in FIG. 2, the angle with respect to the axis of the ball 25, which is held in contact with the holding roller 26 and the rolling surfaces 23a and 24a of the friction plates 23 and 24, is changed within a plane in which the axis of rotation passes through the axis. .

If this axis of rotation is parallel to the axis, the effective radius r from the center of rotation of the ball 25 to the rolling surface of the friction plates 23 and 24
, 1. r2 becomes equal and the gear ratio becomes 1:1.

If the rotation axis tilts to the right, the effective radius r1 becomes larger than r2, the gear ratio becomes 1 or less, and the driven shaft 31 is decelerated.

Furthermore, if the axis of rotation tilts to the left, the effective radius r2 becomes larger than rl, the gear ratio becomes 1 or more, and the speed of the driven shaft 31 is increased.

Pump discharge fluid acts on the sides of the side plates 43 and 44 opposite to the sliding surfaces of the pump rotor, and fluid pressure is applied in opposite directions.

Since the effective area A on which the fluid pressing force of the side plate 44 acts is larger than the effective area B on which the fluid pressing force of the side plate 43 acts, the fluid pressing force acting on the side plate 44 is larger than that. The side plate 43 is pressed rightward in the drawing via the cam ring 40 by an area difference (A-B).

This pressing force is applied to the driven shaft 31 and the friction plate 2 through the bearing 32.
4, the rolling surface 2 of the ball 25 and the friction plate 23, 24
3a and 24a to generate contact pressure.

This contact pressure is also provided by a spring 46 that presses the side plate 44.

Therefore, when there is no pump load pressure, contact pressure is generated by the spring 46 and the rotation of the driving shaft 28 is transmitted to the driven shaft 31.

In this case, since the pump driving torque is small, slippage does not occur even with a weak contact pressure on the transfer surface.

When the pump load pressure increases, the pressing force of the side plate 44 by the fluid also increases, increasing the contact pressure and making it possible to transmit power according to the pump drive torque.

4 and 5, 80 is a pressure relief valve, and this pressure relief valve 80 has a communication hole 84 bored in the pump body 20 to communicate the fluid delivery path 68 after passing through the throttle 70 and the annular flow path 63. A plug 89 having a spring 85, a spring receiver 86, a ball valve 87, and a valve seat 88 is inserted into the communication hole 84.

This pressure relief valve 80 functions to open the ball valve 87 and release the pump discharge fluid to the suction side when the pump load pressure becomes high and exceeds the set pressure of the spring 85.

During a high load operation where continuous fluid flow through the power steering device 18 is blocked, the entire amount of pump discharge fluid is released from this pressure relief valve 80 into the oil tank, so the pressure difference before and after the throttle 70 is reduced to The same pressure difference as before the relief valve 80 was opened is maintained, thereby keeping the gear ratio constant without change.

Therefore, when the load is released, the flow through the power steering device 18 is reproduced, so that the original state can be immediately restored by simply closing the pressure relief valve 80, and disturbances in the flow rate characteristics can be eliminated.

As described above, the pump device of the present invention has a pressure relief valve 80 in which the gear ratio is automatically controlled so that the pressure difference before and after the throttle 70 remains constant even if the rotational speed of the engine rotating shaft 1 changes. Since it is installed in the delivery path after passing through the throttle 70, the pressure difference before and after the throttle 70 can be kept constant even during pressure relief operation, and the speed ratio does not change, so the pump flow rate characteristics can be adjusted to match the pressure relief valve. Immediately after closing, it can be stabilized and has the effect of improving the steering feel.

[Brief explanation of drawings]

The drawings all show embodiments of the present invention, and Fig. 1 is an explanatory diagram of the operating principle, Fig. 2 is a longitudinal sectional view of a pump device incorporating a continuously variable transmission, and Fig. 3 is an illustration of the I in Fig. 2. -DI arrow sectional view, FIG. 4 is a 1V-IV arrow sectional view in FIG. 2,
5 is a sectional view taken along the line V-■ in FIG. 4, and FIG. 6 is a sectional view taken along the line VI-VI in FIG. 4. 1...Engine, 2...Continuously variable transmission,
3... Pump, 10... Delivery path, 11
, 70... Throttle, 12... Gear ratio control cylinder, 20... Pump body, 23, 24
...Rotating friction plate, 25...Ball, 2
6... Holding roller, 27... Holding case, 28... Driving shaft, 31... Driven shaft, 40... Cam ring, 41 ...Vane, 42...Pump rotor, 43.44...
... Side plate, 45 ... Lid body, 48 ...
Cylinder, 49...Piston, 53...
・Rod, 54...The hook is the member, 68...
...Delivery path, 80...Pressure relief valve.

Claims (1)

[Claims] 1. A throttle is disposed in the fluid delivery path of a pump device driven from the engine rotating shaft via a continuously variable transmission, and a pressure responsive device operated by the pressure difference before and after the throttle is connected to the transmission mechanism of the continuously variable transmission. A pressure relief valve is connected to a pressure relief valve that is opened when the pressure in the fluid delivery path exceeds a set pressure and releases fluid to the suction side of the pump device to maintain the pressure difference before and after the throttle. A pump device with a continuously variable transmission characterized by being installed on a road.