JPS61294281A - Pressure reducing valve type pilot valve - Google Patents

Abstract

PURPOSE:To prevent misoperation by forming a cylinder in a casing, providing a pusher with a piston for separating the cylinder into two chambers and disposing a speed reducing valve device between the chambers. CONSTITUTION:A cylinder 33A is formed in the axially intermediate portion of an insertion hole 32A of a casing 31, and a piston 35A of a pusher 34A is slidably fitted into the cylinder 33A so as to separate the cylinder 33A into two chambers A, B. A speed reducing valve device 36A provided for reducing the pushing speed of the pusher 34A is composed of a check valve 37A and a restriction 38A. This assures prevention of misoperation of the pusher due to abrupt handling.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a pilot valve that operates an actuator such as switching control of a directional valve, and in particular to a pilot valve that reduces the hydraulic pressure supplied from a hydraulic pressure source and outputs it. This invention relates to a manually operated pressure reducing valve type pilot valve that can be operated manually.

[Prior art]

BACKGROUND ART In recent years, construction machines, civil engineering machines, and the like have become larger, faster, and more sophisticated, and as a result, hydraulic circuits have become more complex, and the flow rate of pressure oil flowing through the hydraulic circuits has also tended to increase. As a result, hydraulic pumps with larger capacities have come to be used, and directional control valves have also become larger. In order to easily perform spool switching control of the directional switching valve, tilting control of the variable displacement pump, etc., a hydraulic pilot system is adopted in which these controls are performed using a pilot valve. As this pilot valve, a pressure reducing valve type pilot valve, which allows easy pilot pressure control, is widely used.

Figure 2 shows a pressure reducing valve type pilot valve according to the prior art.
The pilot valve that controls switching of the directional control valve is shown.

In the figure, 1 indicates a casing, and the casing 1 has a pump port 3A into which pressure oil from the hydraulic pump 2 flows.
, 3B, and a tank port 5A that constantly communicates with the tank 4.
, 5B are drilled.

Plugs 6A, 6 fitted into the casing 1
Output port doors A and 7B are formed in B. Each pump bow) 3A in the casing l.

3B, tank port) 5A, 5B and output port port A
, 6B are formed, and the flow paths 8A and 8B are formed to communicate with the flow paths 8A and 6B.
Spools 9A and 9B are slidably inserted into A and 8B. The spool 9A.

9B has oil passage 10A, IOB and armhole 11A.

11B is provided, and output capo) 6A and 8B are sleeve holes 11
A, 11B, each tank port 5A, 5B or each pump port 3 via oil path 10A, IOB and flow path 8A, 8B
It is selectively distributed to A and 3B.

12A and 12B are pushers for slidingly displacing each of the spools 9A and 9B;
is slidably inserted into insertion holes 13A and 13B provided in the casing l, its upper end protrudes outside the casing 1, and its lower end is formed in the casing l (tank bow) 5
It faces into the spring chambers 14A and 14B which are constantly in communication with the spring chambers A and 5B. 15A and 15B are the respective spring chambers 14A.

A balance spring provided in 14B, each spring 15
A and 15B are each pusher 12A and 12B and spool 9A
, 9B. On the other hand, 16A, 1f
5B is each pusher 12A.

The return springs 16A and 16B are tensioned between the balance spring 12B and the casing l.
It has a smaller set load than 5A and 15B.

Next, 17 is a substantially inverted T-shaped operating rod rotatably attached to the bracket 18 of the casing 1.

The operating rod 17 includes a pair of left and right suppressing parts 17A, 17B that press the tips of the pushers 12A, 12B, and the pressing part 17.
It consists of a lever part 17C that protrudes upward from the middle of the suppressing parts 17A and 17B, and the length Ilr of each suppressing part 17A and 17B is
In contrast, the length 22 of the lever portion 17G is five times as long.

In addition, 19 in the figure is a directional switching valve, and pilot chambers 19A and 19B of the directional switching valve are piping 20A.

It is connected to output port doors A and 7B via 20B. Further, 21 is an actuator that is operated to switch between directions by the directional switching valve 19, and 22 is a main pump that drives the actuator 21.

The pressure reducing valve type pilot valve according to the prior art has the above-mentioned configuration, and its operation will be explained next. First, when the operating rod 17 is in the neutral position where it is not rotated,
Balance spring 15A.

The pushers 12A, 12B have their tips protruded from the casing l by the spring force of the return springs 16A, 16B, the spools 9A, 9B are located north in the figure, and the output port doors A, 7B are connected to the oil passages LOA, IOB, Armhole 11A
, IIB are in communication with tank ports 5A and 5B sequentially. Therefore, each pilot chamber 19A, 19B of the directional control valve 19 becomes equal pressure, and the directional control valve 19
is held in a neutral position.

Next, when the operating rod 17 is rotated in the direction of the arrow in FIG. 2, the pushing part 17A presses the pusher 12A. pusher 12
When A is pressed, the balance spring 15A deflects and slides the spool 9A downward in the figure. As a result, the armhole 11A is cut off from communicating with the tank port 5A, and is made to communicate with the pump port 3A. As a result, the pressure oil of the hydraulic pump 2 is discharged from the port via the pump port 3A, the armhole 11A, and the oil passage 10A in sequence. ) 7A to the pilot chamber 19A of the directional switching valve 19, and the directional switching valve 19 is operated to switch.
The supply of pressure oil from the main pump 22 to the seven cutout units 21 is switched.

As described above, when pressure oil is supplied from the pump port 3A into the oil passage 10A through the armhole 11A, the oil passage 1
The pressure inside 0A becomes high, and the spool 9A is pushed upward in the figure against the spring force of the balance spring 15A. As a result, the sleeve hole 11A is cut off from the pump bow 3A and communicated with the tank port 5A, resulting in low pressure in the oil passage 10A, and the spool 9A is again slid downward in the figure by the spring force of the spring 15A. , pump port) 3A and the sleeve hole 11A communicate with each other. In this way, the spool 9A repeats the fine L downward movement to reduce the pressure in the pump port 3A and supply it to the pilot chamber 19A of the directional control valve 19.
The directional control valve 1
Convert spool 9 to the switching position.

By the way, in order to manually operate the pushers 12A and 12B of the pair of pressure reducing valve type pilot valves described above, conventionally,
Although the operating rod 17 is rotatably provided on the casing 1, it has the following drawbacks.

That is, when the pressure reducing valve type pilot valve is mounted on a civil engineering/construction vehicle, the pressing portion 17A of the operating rod 17,
Length 22 of lever part 17c relative to length Ill of 17B
This means that the amount increases by 5 to 30 times. Therefore, the inertia force due to the speed change of the vehicle acts on the lever part 17C, causing the operating rod 17 to swing, causing the pusher 12A (
12B) may cause the spool of the directional control valve 19 to be switched.

As a means to solve the above-mentioned drawbacks, the return spring 16
A, 16B spring force is set large, pusher 12A,
Although it is conceivable to prevent 12B from being pushed by the inertia of the operating rod 17, there is a problem in that a large force is required to operate the operating rod 17, resulting in poor operability.

[Problem that the invention seeks to solve]

The present invention has been made in view of the above-mentioned drawbacks of the prior art, and the problems to be solved by the present invention are to prevent malfunctions caused by swinging of the operating rod, and to provide a feeling of operation that corresponds to the operating speed. The object of the present invention is to provide a pressure reducing valve type pilot valve that can be obtained.

[Means for solving problems]

The features of the means of the present invention configured to solve the above-mentioned problems are that the casing is provided with a cylinder, the pusher is provided with a piston that divides the cylinder into two chambers, and a speed reducer is provided between each chamber. This is because a valve device is provided.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail based on FIG.

Note that the same reference numerals are given to the same components as those of the prior art described above, and the explanation thereof will be omitted. Furthermore, in this embodiment, since the negative pressure reducing valve type pilot valve and the other pressure reducing valve type pilot valves have the same configuration, only the negative pressure reducing valve type pilot valve will be described.

In the figure, 31 is the casing, and 32A is the pusher 12.
A large diameter cylinder 33A is formed in the axial direction of the insertion hole 32A. 34A is a cylindrical pusher slidably inserted into the insertion hole for slidingly displacing the spool 9A, and 35A is the pusher 34A.
The piston 35A is slidably inserted into the cylinder 33A, and defines the cylinder 33A into two chambers A and B.

36A is used to reduce the pressing speed of the pusher 34A, and the two chambers A, BF! In the reduction valve device installed in JI, the reduction valve device; 136A is a check that allows the flow of oil from chamber A to chamber B, but conversely blocks the flow of oil from chamber B to chamber A. A valve 37A and each chamber A, B in parallel with the check valve 37A.
and a diaphragm 38A provided in between.

This embodiment is constructed as described above, and by rotating the operating rod 17 and pressing the pusher 34A to slide the spool 9A, the output port door A is connected between the pump port 3A and the tank port 5A. There is no substantial difference from the prior art in that the pump pressure is switched between the two pumps, the pump pressure is reduced, and a pilot pressure corresponding to the push amount of the pusher 34A is outputted from the pusher 7A.

According to this embodiment, the pusher 34A is provided with a piston 35A that defines the cylinder 33A provided in the casing 31 into two chambers A and H.

A deceleration valve system 2-36A is installed between the two chambers A and B. Therefore, when the operating rod 17 is operated at a normal speed to press the pusher 34A, the piston 35A
The flow of hydraulic fluid moving from chamber B to chamber A in response to 34A can be responded to.

On the other hand, if the operating rod 17 is manually operated suddenly or if the operating rod 17 suddenly swings due to inertia due to a change in vehicle speed and presses the pusher 34A, the movement from chamber B to chamber The flow of hydraulic fluid moving to A is through check valve 37A.
However, the flow rate of the hydraulic fluid is further restricted by the restrictor 3.
8A, the sliding speed of the piston 35A is suppressed, and as a result, the pusher 34A is
A large resistance force (braking force) is exerted against the operating speed.

Further, when the pressing force of the operating rod 17 against the pusher 34A is released, the pusher 34A is pushed back upward in the figure by the spring force of the return spring 16A, so that the chamber A in the cylinder 33A is also reduced by the piston 35A. , the hydraulic fluid in the chamber A flows to the chamber B side, but at this time the check valve 3
Since the valve 7A is opened, the flow of the hydraulic fluid is not obstructed, and therefore the pusher 34A can quickly return to the neutral position.

According to the present embodiment, as shown in FIG. In other words, even if the operating rod 17 is suddenly operated due to inertial force, the sliding speed of the pusher 34A can be kept constant, thereby preventing the directional control valve 19 from being suddenly switched. Further, in this embodiment, by appropriately selecting the flow rate of the throttle 38A, the operator receives resistance corresponding to the pressing speed applied to the pusher 34A, and as a result, a realistic and excellent operational feeling can be obtained.

〔Effect of the invention〕

Since the present invention is configured as described in detail above, it is possible to reliably prevent the pusher from malfunctioning due to swinging of the operating rod or sudden operation by the operator. It provides an excellent operating feel.

[Brief explanation of the drawing]

Fig. 1 is an enlarged sectional view of the main parts of a pressure reducing valve type pilot valve according to an embodiment of the present invention, and Fig. 2 is a vertical cross section of a pressure reducing valve type pilot valve according to the prior art used for switching control of a directional control valve. It is a diagram. 3A, 3B...Pump port, 5A, 5B...Tank port, 7A, 7B...Output port, 9A, 9B
...Spool, 31...Kaizong, 33A...
Cylinder, 34A...Pusher, 35A...Piston, 36A...Reduction valve device.

Claims (1)

[Claims] a casing having a pump port, a tank port, and an output port; a spool provided within the casing for switching the output port between the pump port and the tank port; and a spool that engages with the spool to slide the spool. In the pressure reducing valve type pilot valve, the pressure reducing valve type pilot valve has a pusher to slide the spool by pressing the pusher to reduce the liquid pressure from the pump port and supply the reduced liquid pressure to the output port. A pressure reducing valve type pilot valve, characterized in that the pusher is provided with a piston that defines the cylinder into two chambers, and a deceleration valve device is provided between each chamber.