JPH0245569Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The electromagnetic pilot operated directional valve of this invention is used to form a hydraulic circuit.

[Conventional technology]

Conventionally, an electromagnetic pilot-operated directional control valve forming a hydraulic circuit is shown in Fig. 2 (Japanese Unexamined Patent Publication No. 59-80588).
There are some things shown below.

This electromagnetic pilot operated directional control valve includes a spool type directional control valve 1 having a spool 2, an electromagnetic pilot operating part 3 connected to the right end of the spool type directional control valve 1, and a manual operating part 4 connected to the left end. The spool 2 is operated by either an electromagnetic pilot operating section 3 or a manual operating section 4. Note that the manual operation unit 4 is a part that is not related to this invention, so a description thereof will be omitted hereafter.

The electromagnetic pilot operating section 3 has pistons 6a and 6b slidably fitted into the main body 5 fixed to the right end of the spool-type directional control valve 1, and the left side of the piston 6a and the right side of the piston 6b are provided with the following parts. It has pressure chambers 8a, 8b connected to electromagnetic pressure control valves 7a, 7b. These pressure chambers 8a, 8b are
It is connected to the pilot hydraulic pressure source 10 via throttles 11a and 11b, and the tank T is connected to an electromagnetic pressure control valve 7.
A, 7b are connected via poppet valve portions 12a, 12b. Note that the intermediate chamber 13 formed between the pistons 6a and 6b is connected to the tank T or the pilot hydraulic pressure source 10 via a pilot valve 14, and the pilot valve 14 is connected to the pressure chambers 8a and 8b. It is configured to operate using hydraulic pressure.

The piston 6a and the spool 2 are arranged such that the right end 2a of the spool 2 passes through the connecting member 15a and is connected to the pressure chamber 8a.
The pressure chamber 8a protrudes from the pressure chamber 8a and is connected to the pressure chamber 8a. Therefore, the pressure receiving area of the piston 6a is the value obtained by subtracting the cross-sectional area of the right end 2a of the spool 2 from the cross-sectional area of the piston 6a. For this reason, a rod 16 that penetrates the end cover 15b of the main body 5 and protrudes to the outside is fixed so that the value of the pressure receiving area of the piston 6b is equal to the pressure receiving area of the piston 6a. A sealing member 17 is provided at the sliding portion with respect to 16. Reference numeral 18 denotes a neutral position return device for the manual operation section 4, which is fixed to the rod 16.

In the electromagnetic pilot-operated directional valve configured as described above, when an actuation signal of a predetermined value is applied to the electromagnetic pressure control valve 7b, the poppet valve portion 12b closes between the pressure chamber 8b and the tank T. 8b pilot oil pressure begins to rise. This pilot oil pressure operates the pilot valve 14 to connect the intermediate chamber 13 to the pilot oil pressure source 10. Therefore, the pistons 6a and 6b are integrated in the state shown in FIG. On the other hand, the pilot oil pressure in the pressure chamber 8b increases in response to the closing force of the poppet valve portion 12b, causing the spool 2 to move to the left along with the pistons 6a and 6b.
The piston 6b is moved to a position where the pressing force acting on the piston 6b and the reaction force of the return spring 9a are balanced. Similarly,
When an actuation signal of a predetermined value is applied to the electromagnetic pressure control valve 7a, the intermediate chamber 13 is connected to the pilot oil pressure source 10, the pilot oil pressure in the pressure chamber 8a increases, and the spool 2 moves to the right together with the pistons 6a and 6b. be moved.

[Problem that the invention attempts to solve]

As described above, this electromagnetic pilot operated directional switching valve controls the pilot oil pressure in the pressure chambers 8a, 8b using the electromagnetic pressure control valves 7a, 7b to switch the spool 2. The amount of movement of the spool 2 is determined by the balance between the pressing force of the pressure chambers 8a, 8b due to the pilot oil pressure and the pressing force of the return springs 9b, 9a. Therefore,
In order to make the operating signal to the electromagnetic pressure control valve and the operating amount of the spool the same on the left and right sides, the pistons 6a and 6b are used.
It is necessary to equalize the pressure receiving area of the two. However, since the pressure chamber 8a is connected to the tank passage T8 of the directional control valve, some oil leakage from the pressure chamber 8a to the tank passage T8 can be tolerated;
Since b is in contact with the outside, there is little tolerance for oil leakage. Therefore, it is necessary to attach a seal member 17 to the sliding surface between the rod 16 and the end cover 15b. This sealing member 17 is connected to the pressure chamber 8
It is pressed outward by the hydraulic pressure acting on b and is also pressed against the surface of the rod 16. Therefore, the resistance is greater when the spool 2 moves to the left than when it moves to the right, and this invention attempts to solve this problem.

[Means for solving problems]

An electromagnetic pilot operating section is connected to one end of the valve body of the spool-type directional control valve, and the electromagnetic pilot operating section forms two pressure chambers in its main body in which pilot hydraulic pressure is controlled by an electromagnetic pressure control valve. A piston is slidably inserted into the two pressure chambers, return springs are provided in the two pressure chambers, one end of the spool of the spool-type directional control valve is inserted into one of the pressure chambers, and this one end is connected to the piston. Along with being
In an electromagnetic pilot operated directional control valve configured such that a rod connected to the piston and having the same diameter as the spool passes through the other pressure chamber,
A bushing and a sealing member are sequentially provided from the pressure chamber side of the electromagnetic pilot operating portion connected to the piston in a portion penetrating the main body thereof, and the bushing and the sealing member are connected to the tank.

[Effect]

In the present invention, even if the pilot pressure oil supplied to the pressure chamber leaks to the seal member through the bush, the pilot oil pressure will not act on the seal member because it will flow into the tank.

〔Example〕

An embodiment of the present invention shown in FIG. 1 will be described below. Note that parts that are the same as those in the prior art are given the same reference numerals and their explanations will be omitted.

In FIG. 1, an end cover 20 is fixed to the right end of the main body 5 of the electromagnetic pilot operating section 3, and a rod 16 passes through the end cover 20. The rod 16 is held by a bushing 21 provided on the end cover 20, and a sealing member 17 is attached thereto, and the sealing member 17 and the bushing 21 communicate with the tank T via a passage 22. A chamber 23 is formed. Note that the bush 21 is mounted in a groove 25 with a retainer 24. By making the bush 21 movable in the radial direction of the rod 16, it is possible to absorb misalignment between the axes of the rod 16 and the end cover 20.

In the above configuration, when pilot pressure oil is supplied to the pressure chamber 8b, the pistons 6a, 6b move the spool 2 to the left. When the spool 2 is moving leftward and is stopped at a predetermined position, pilot oil pressure acts on the pressure chamber 8b. This pressure oil leaks through the bush 21, and this leaked oil flows out into the tank T through the passage 22.

[Effect of idea]

As described above, the electromagnetic pilot operated directional valve according to the present invention is designed so that no resistance is caused by the pilot oil pressure in the electromagnetic pilot operating part, so that the command value depending on the operating direction is the same, and the command value is the same depending on the operating direction. This has the effect of reducing the hysteresis that exists in the relationship between the value and the stroke of the spool.

[Brief explanation of drawings]

FIG. 1 is a sectional view of essential parts of an embodiment of this invention.
FIG. 2 is a sectional view of a conventional electromagnetic pilot operated directional valve. 1... Valve body, 2... Spool, 2a... One end,
3... Solenoid pilot operating section, 6a, 6b... Piston, 7a, 7b... Solenoid pressure control valve, 16...
... Rod, 17 ... Seal member, 20 ... End cover,
21...butsuyu, 22...aisle.

Claims (1)

[Scope of utility model registration request] An electromagnetic pilot operating section is connected to one end of the valve body of the spool-type directional control valve, and the electromagnetic pilot operating section forms two pressure chambers in its main body in which pilot hydraulic pressure is controlled by an electromagnetic pressure control valve. A piston is slidably inserted into the two pressure chambers, return springs are provided in the two pressure chambers, one end of the spool of the spool-type directional control valve is inserted into one of the pressure chambers, and this one end is connected to the piston. and the other pressure chamber is connected to the piston,
In an electromagnetic pilot operated directional valve configured to be penetrated by a rod having the same diameter as the spool,
A bush and a seal member are provided in order from the pressure chamber side at a portion where the rod connected to the piston passes through the main body of the electromagnetic pilot operating section, and
An electromagnetic pilot operated directional valve characterized in that a bush and a sealing member are connected to a tank.