JPS58187667A - Controlling valve - Google Patents

Abstract

PURPOSE:To obtain automatically the output of an engine in accordance with load, by extending a spool having a small diameter section and energized by a spring through an orifice that divides a space in a valve body into two parts, and pressing the spool against the spring by a fluid pressure. CONSTITUTION:In case an engine 1 is started to rotatably drive a charge pump 2 and an HST pump 3, the outflow of the pump 2 is low, the pressure difference between the left chamber 11 and the right chamber 12 of the control valve body 8 is low, an actuator 25 is not actuated, a slant plate 7 of the pump 3 is neutral and the HST motor 4 is not rotated. When the output of the engine 1 is increased, the outflow of the pump 2 increases, the pressure difference between the chambers 11, 12 is produced, the actuator 25 is actuated, the slant plate 7 is moved, the pump 3 discharges pressure oil, and the motor 4 is rotated. When the load on a cylinder 5 is increased, the pressure in the discharge circuit 22 of the pump 2 increases to push a piston 21 to the left, the spool 13 is forced to the left, and the orifice 14 is opened to reduce the pressure difference between the chambers 11, 12.

Description

[Detailed description of the invention] The present invention relates to control valves, for example control valves for hydraulically driven vehicles.

As shown in FIG. 1, a conventional hydraulically driven vehicle is equipped with a charging pump 2 and an H8T pump 3 connected to the drive shaft of an engine 1, and the oil inlet and outlet of the HAT pump 3 is connected to the HBT motor 4 through hydraulic piping. The H8T motor 4 was connected to the oil inlet and outlet, and the wheels connected thereto were driven to rotate. In the figure, 5 is a cargo handling cylinder, and 6 is a control valve.

In the above structure, the speed of the hydraulically driven vehicle was controlled by manually controlling the swash plate 7 of the H8T pump 3.

In this case, when the load on the charging pump 2 is large during cargo handling work, if the swash plate 7 is operated to increase the vehicle speed, the H8T
There is a problem in that the load on the pump 3 increases, and the load on the connection 1 + U connection 1 increases rapidly, causing the engine to stop.

For this reason, in order to perform cargo handling work or increase vehicle speed, it was necessary to increase the engine rotational speed in advance and then perform the above operations, which placed a heavy burden on the driver. .

The present invention has been made in order to solve the above two defects and problems, and its purpose is to provide a control valve that enables a control circuit that automatically obtains engine output according to the load. .

Hereinafter, the present invention will be explained based on FIG. 2. In the control valve of the present invention, a space 9 provided inside a control valve body 8 is connected to a left ventricle 11 by an orifice plate 10 fixed to a wall surrounding the space 90. The right chamber 12 is divided into the right chamber 12, and a spool 13 having a slightly smaller diameter than the bulge 51 of the orifice plate 10 is slidably passed through the hole 10a of the orifice plate 10 and the outer periphery of the spool 13. An orifice 14 is formed by the surface, and when the spool 13 is in a neutral state, a small diameter portion 15 is formed over a certain section to the right from a position corresponding to the orifice plate IO, and a spring 16 that biases the spool to the right is formed. A fluid inlet 17 and an inlet pressure outlet 18 are provided in the left chamber 11, a fluid outlet 19 and an outlet pressure outlet 20 are provided in the right chamber, and a piston 21 that presses the spool 13 to the left is provided. It is provided so as to come into contact with the right end 13a of the spool 13.

In addition, in this embodiment, the charging pump 2
The output circuit 22 is connected to the fluid port 17 of the control valve body 8 and the piston 21, and the outlet circuit 23 of the fluid outlet 19 is connected to the control valve 6. p(yo inch”/
5° Further, the inlet pressure outlet 18 and the outlet pressure outlet 20 are connected to an actuator 25 via a forward/reverse switching valve 24, and the actuator 25 operates; 16 is the HS T pump 3. is connected to control the swash plate 7 of. The pistons 21a and 21b arranged in parallel with the piston 21 are configured to move according to the oil pressure of the H6Tl-transmission T.

Next, to explain the operation, the engine 1 is started and the char sink pump 2 and the H8T pump 3 are rotationally driven. At this time, since the flow rate of the pressure oil discharged from the charging pump 2 is small, the pressure difference between the left chamber 11 and the right chamber 12 of the control valve body 8 is small.
Since the actuator 25 is not operated, the swash plate 7 of the H8T pump 3 is in the neutral position. Therefore, the H8T pump 3 does not discharge pressure oil, and therefore the H6T motor 4 does not rotate.

Next, when the output of engine 1 is further increased and the rotation speed is increased,
The rotational speed of the charging pump 2 also increases, and the amount of pressure oil discharged increases. Therefore, the flow rate passing through the orifice 14 also increases, creating a pressure difference between the left chamber 11 and the right chamber 12. This pressure difference actuates actuator 25 to move swash plate 7 from its neutral state.

When the swash plate 7 moves, the H8T pump 3 discharges pressure oil. The H8T motor 4 is rotationally driven by this pressure oil, the wheels rotate, and the vehicle travels.

At this time, when the load on the cargo handling cylinder 5 increases, the pressure at the discharge port 1% 22 of the charging pump 2 increases, pushing the piston 21 to the left. Therefore, the spool 13 moves to the left, the opening area of the orifice 14 increases, and the pressure difference between the left chamber 11 and the right chamber 12 decreases. When this pressure difference decreases, the actuator 25 returns to the neutral position,
The swash plate 7 also returns to the neutral position, the vehicle stops, and the load on the engine 1 is prevented from increasing.

In order to make the vehicle run further in this state, the output of the engine 1 may be further increased to increase the rotational speed.

As is clear from the above description, in the control valve of the present invention, a space 9 provided inside the control valve body 8 is connected to a left ventricle 11 and a right ventricle 1 by an orifice plate 1'0 fixed to the peripheral wall of the space 9.
A spool 13 having a diameter slightly smaller than that of the orifice plate 10 is slidably penetrated into the blue band of the orifice plate 10, and an orifice 14 is formed by the inner peripheral edge 10a of the hole of the orifice plate 10 and the outer peripheral surface of the spool 18. , the spool 13
A small diameter portion 15 is formed in a certain section to the right from a position corresponding to the orifice plate 10 in a neutral state, ])1
1. A spring 16 that urges the spool to the right is provided, and a piston 21 that pushes the fluid intake 17 and the pressure outlet 13 to the left into the left chamber 11 is located at the right end 13a of the spool 13.
It is provided so that it comes into contact with the Therefore, if a control circuit is configured using the control valve of the present invention, the opening area of the orifice can be changed according to the load, and the swash plate of the H6T pump can be controlled by the pressure difference before and after the orifice. The engine output is automatically obtained according to the engine speed, and has the excellent effect of solving the conventional problem of the engine stopping when the vehicle starts.

8: Control valve body, 9: Space, lO nitric orifice plate, 11
: left ventricle, 12: right ventricle, 13 nis spool, 14 niorifice, ] 5: small diameter section, 16 two strokes, 17: fluid inlet, 18
Two person pressure outlet, 19: fluid outlet, 20: outlet pressure outlet, 21: piston.

Applicant: Toyo Yusoki Co., Ltd. Agent Hisashi Nakamura

Claims (1)

[Claims] A space in which the control is provided inside the main body is slidably penetrated by a small diameter spool in the space, and an orifice is formed by the inner peripheral edge of the hole in the orifice plate and the outer peripheral surface of the spool, and the spool is in a neutral state. In this state, a small diameter portion is formed in a certain section to the right from a position corresponding to the orifice plate, a spring is provided for biasing the spool to the right, and a fluid inlet and an inlet pressure outlet are provided in the left chamber. A control valve characterized in that the right chamber is provided with a fluid [1] and an outlet pressure outlet, and a piston that presses the spool to the left is provided so as to come into contact with the right end of the spool.