JPH0226375A - Oil pressure pilot type direction changeover valve - Google Patents

Abstract

PURPOSE:To improve responsibility at starting when a spool is slidingly moved from a neutral position to a changeover position, by shutting down one oil pressure pilot chamber from tank ports and communicating the other oil pressure pilot chamber with tank ports. CONSTITUTION:A spool 25 is received in a valve body 11 in which a pump port 18, tank ports 19, 20A, 20B, actuator ports 21A, 21B are formed. The end part lends 29A 29B of the spool 25 are protruded into a pilot chamber 23A and a spring chamber 24 and also oil passages 43A, 43B are respectively formed on the end part lands 29A, 29B. By actuating pilot pressure in the pilot chamber 23A, the spool 25 is slidingly moved in the right direction. At this time, a pilot chamber 23B is communicated with the tank port 20B through the oil passage 43B, hereby, oil in the pilot chamber 23 is rapidly discharged, and the spool 25 is instantly changed over from the neutral position to the changeover position.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is provided in a construction machine such as a hydraulic excavator, and is capable of switching from a neutral position to a switching position by supplying pilot pressure when tilting a control lever. The present invention relates to a hydraulically pilot operated directional valve.

[Conventional technology]

8 to 10 show prior art hydraulic pilot type directional control valves.

In the figure, l indicates a main hydraulic pump constituting a main hydraulic pressure source, and 2 indicates a tank. The hydraulic pump l and tank 2 are connected to an actuator, for example, hydraulic pressure for driving a hydraulic excavator, through a pair of main pipes 3A and 3B. It is connected to a motor (not shown), etc. Reference numeral 4 indicates a hydraulic pilot type directional switching valve (hereinafter referred to as switching valve 4) provided midway between the main pipes 3A and 3B. It is switched from left to right switching position (b), (c), and the switching position (b),
In (c), the hydraulic motor is rotated in the forward and reverse directions, and stopped at the neutral position.

Reference numeral 5 indicates a pressure reducing valve type pilot valve installed in a driver's cab of a hydraulic excavator, and the pilot valve 5 includes a pair of pressure reducing valves 5A and 5B and the pressure reducing valve 5A.

5B and an operating lever 5C that is operated to set the pressure. Further, the high pressure side of the pressure reducing valves 5A and 5B of the pilot valve 5 is connected to a sub-pump 6 as a pilot hydraulic pressure source.

The low pressure side is connected to the tank 2 via a check valve 34 (described later), and the output side is connected to the hydraulic pilot chambers 23A, 2 of the switching valve 4 via a pair of pilot pipes 7A, 7B, etc.
Connected to 3B. By tilting the operating lever 5C in the directions of arrows A and B, the pilot valve 5 supplies pilot pressure proportional to the operating amount from the pressure reducing valves 5A and 5B to the hydraulic pilot chambers 23A and 23B. It looks like this.

8A and 8B indicate a pair of speed control valves provided in the middle of the pilot pipes 7A and 7B, and the speed control valve 8A
, 8B are throttle valves 9A, 9B and check valves 10A, IOB.
and the throttle valve 9A.

9B exerts a throttling effect on the oil flowing through the pilot pipes 7A and 7B, and suppresses the sliding speed of the spool 25, which will be described later, to a relatively slow speed. Also, the check valves 10A and IOB are provided in parallel with the throttle valves 9A and 9B, and the pilot pressure from the pressure reducing valves 5A and 5B is transferred to the hydraulic pilot chamber 23A.

It is distributed only towards the 23B side.

Next, the above-mentioned switching valve 4 will be described in detail with reference to FIGS. 9 and 10. Reference numeral 11 indicates a valve body of the switching valve 4. A spool sliding hole 12 drilled in the main body 11, a central oil groove 13 formed in the peripheral wall of the spool sliding hole 12, and spaced apart in the axial direction of the spool sliding hole 12, and left and right oil grooves. Groove 14A
.

14B, 15A, 15B, 16A, 16B, 17A, 1
7B, and a pump port 1 that communicates the hydraulic pump l and the spool sliding hole 12 via the oil grooves 13.15A and 15B.
8 and oil groove 14A.

A central tank port 19 and left and right tank ports 20A that communicate the tank 2 and the spool sliding hole 12 via ports 14B, 17A, and 17B.

20B, and left and right actuator side bows 21A and 21B (see FIG. 10) that communicate the hydraulic motor and the spool sliding hole 12 via oil grooves 16A and 16B.

And the actuator side port 21A.

21B is connected to main pipes 3A and 3B, and pump port 18 and tank ports 19, 2OA, and 20B are connected to main pipe 3
It is connected to a hydraulic pump 1 and a tank 2 via A and 3B, respectively. Further, the valve body 11 is provided with lid members 22A and 22B that are located on both ends of the spool sliding hole 12 in the axial direction and form a part of the valve body 11, and the lid members 22A.

Hydraulic pilot chambers 23A and 23B are formed in 22B and are located at both ends in the axial direction of the spool 25, which will be described later, and are connected to pilot pipes 7A and 7B. A spring chamber 24 is formed in the lid member 22B on the right side in the figure, located between the spool sliding hole 12 and the pilot chamber 23B.
The spring chamber 24 communicates with a pilot chamber 23B.

Reference numeral 25 indicates a spool that is slidably inserted into the spool sliding hole 12, and the spool 25 has an oil groove 14A that is located in the central oil groove 13 when in neutral, and an oil groove 14A between the oil groove 13 and the oil groove 14A when sliding. 1
A central land 26 having notches 26A and 26B that communicate with and block communication between the central land 26 and the oil groove 13.4-B, and an oil groove 13. When disconnecting the communication 1B between the oil grooves 14A and 14B, the oil grooves 15A and 15B and the oil lll 6
A.

In addition to blocking and communicating between 16B and notches 27A and 27
The left and right switching lands 28A and 28B have oil grooves 16A and 16B, and an oil groove 17A located at both ends in the axial direction.
, 17B and which always isolate the oil grooves 17A, 17B from the pilot chambers 23A, 23B and the spring chamber 24 are formed.

30 is screwed onto the end land 29B side of the spool 25,
A rod forming part of the spool 25 is shown, and the mouth 7
The door 30 extends in the axial direction within the spring chamber 24, and its tip end, together with the left end of the spool 25 in the drawing, serves as a stopper part 31A, 3 for regulating the stroke end of the spool 25.
It constitutes 1B. Further, 32 indicates a spring provided in the spring chamber 24 to always bias the spool 25 to the neutral position, and the spring 32 is located around the rod 30 and is connected to the stopper portion 31B of the rod 30 and the end of the spool 25. The outer periphery of each spring receiver 33 is disposed between the bottom surface of the spring chamber 24 and the valve body 1 through spring receivers 33 and 33.
1, respectively.

Furthermore, 34 in FIG. 8 indicates pilot pipes 7A and 7B.
The check valve is shown to pre-pressurize the hydraulic fluid inside.

In the conventional technology configured in this way, when the driver in the driver's cab tilts the operating lever 5C of the pilot valve 5 in the direction of arrow A, the pressure reducing valve 5A checks the pilot pressure from the sub pump 6, such as the check valve 10A, etc. is supplied to the pilot chamber 23A of the switching valve 4, and the spool 25 is slid to the right in the figure against the spring 32 to switch from the neutral position (A) to the left switching position (B). . At this time, the spool 25 is connected to the oil grooves 15A and 16A by the switching land 28A.
The oil grooves 16B and 1 are connected by the end land 29B.
7B, and the other oil grooves 16A, 17A, oil grooves 13, 14A, 14B, etc. are blocked, so that the pressure oil from the hydraulic pump 1 is transferred to the pump bow 18, oil groove 15A.

16A and actuator side bow) 21A, return oil from this hydraulic motor is discharged to tank 2 via actuator side bow) 21B, oil grooves 18B, 17B, and tank port 20B. Also, the oil in the pilot chamber 23B etc. is removed from the spool 25.
As it slides, it is discharged to the evening tank 2 via the throttle valve 9B, pressure reducing valve 5B, etc.

Then, when the operating lever 5C is returned to the neutral position as shown, the pressure reducing valve 5A communicates with the tank 2 and cuts off the supply of pilot pressure, so the spool 25 is returned to the neutral position (A) by the spring 32, and the pilot The oil in the chamber 23A is discharged to the tank 2 via the throttle valve 9A, pressure reducing valve 5A, etc. Also, when the operating lever 5C is tilted in the direction of arrow B, the pressure reducing valve 5B checks the pilot pressure from the sub pump 6 through the check valve 10B and the like to the pilot chamber 23 of the switching valve 4.
B, the spool 25 slides to the left in the figure and is switched to the switching position (c), and the oil in the pilot chamber 23A flows to the tank 2 via the throttle valve 9A, pressure reducing valve 5A, etc. be discharged.

By the way, another conventional technique shown in FIG. 11 is also known, but in this case, the pilot pipe 7A.

Since the speed control valves 8A and 8B are not provided in the middle of the switching valve 7B, when the operating lever 5C is returned to the neutral position, the switching valve 4
The spool 25 suddenly returns to the neutral position (A) by the spring 32, and the hydraulic motor acting as the actuator suddenly stops, resulting in a large stop shock that may cause load spillage or worsen riding comfort. .

Therefore, in the prior art shown in FIG. 8, the throttle valves 9A and 9B
By providing this, a throttling effect is applied to the oil discharged from the pilot chambers 23A, 23B via the pilot pipes 7A, 7B, and the spool 25 is prevented from suddenly returning to the neutral position (A) by the spring 32. are doing. Also,
If only the throttle valves 9A and 9B are provided, the operating lever 5c
When the sub pump 6 is tilted in the directions of arrows A and B,
Pressure oil as pilot pressure from
3B could not be supplied quickly, and the spool 25 was placed in the neutral position It (
A) to switching position (B).

The response when switching to (c) deteriorates. For this reason,
There are throttle valves 9A and 9 in the middle of the pilot pipes 7A and 7g.
By providing speed control valves 8A and 8B consisting of B and check valves 10A and 10B, and providing a check valve 34, at least a certain prepressure is applied to the hydraulic fluid in the pilot pipes 7A and 7B, thereby improving responsiveness. I'm trying to improve it.

[Problem to be solved by the invention]

However, in the prior art described above, 1, for example, the operating lever 5C
When the sub-pump 6 is tilted in the direction of the arrow A, the pilot pressure from the sub-pump 6 is reduced to the pressure-reducing valve 5A.

Although the oil can be quickly supplied to the pilot chamber 23A via the check valve 10A, the oil in the pilot chamber 23B side is discharged into the tank 2 via the throttle valve 9B, etc., so the oil is It is said that the liquid cannot be discharged quickly, that it is difficult to slide the spool 25 at a high speed, and that the responsiveness when switching from the neutral position N (a) to the switching position (b) or (c) cannot be significantly improved. There are drawbacks.

The present invention has been made in view of the above-mentioned drawbacks of the prior art.The present invention is capable of reliably suppressing the shock when stopping an actuator such as a hydraulic motor, and also when starting when switching from a neutral position to a switching position. The present invention provides a hydraulic pilot type directional control valve that can effectively improve responsiveness.

[Means to solve the problem]

The feature of the configuration adopted by the present invention in order to solve the above-mentioned problems is that pilot pressure is supplied to either one of the pair of hydraulic pilot chambers to slide the spool from the neutral position to the switching position. An oil passage is provided in the spool so that one hydraulic pilot chamber is isolated from the tank port and the other hydraulic pilot chamber is communicated with the tank port.

[Effect]

With the above configuration, when pilot pressure is supplied to one hydraulic biloft chamber in order to slide the spool from the neutral position to the switching position, the other hydraulic pilot chamber is communicated with the tank port, and the other hydraulic pilot chamber is connected to the tank port. The oil liquid can be directly discharged to the tank side, and the spool can be quickly slid by pilot pressure.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 3. In addition, in the embodiment, the above-mentioned FIGS. 8 to 1
Components that are the same as those in the prior art shown in FIG.

In the figure, reference numeral 41 indicates a hydraulic pilot type directional switching valve (hereinafter referred to as switching valve 41) according to the present embodiment, and the switching valve 41 is connected to the valve body 11, spool 25, etc. similarly to the switching valve 4 described in the prior art. However, the valve body 11 is formed with annular grooves 42A and 42B located at both ends of the spool sliding hole 12 in the axial direction and opening at the end faces thereof.
Oval oil passages 43A, 43B are formed on the outer peripheral surfaces of the end lands 29A, 29B. Here, the oil path 4
3A and 43B are shorter than the length of the end lands 29A and 29B, but longer than the stroke length of the spool 25 from the neutral position (A) to the stroke end, and the length of the spool 25 is longer than the stroke length from the neutral position (A) to the stroke end. Now, the annular groove 42
A, 42B to pilot chambers 23A, 23B (spring chamber 24), oil grooves 17A, 17B, tank port 20A,
20B.

Then, tilt the operating lever 5C in the direction of arrow A,
When the pilot pressure from the sub pump 6 is supplied to the pilot chamber 23A via the pressure reducing valve 5A, the check valve 10A, etc., and the spool 25 is slid to the right in the figure, one of the oil passages 43A located on the left side is used as the pilot chamber 23A. It is shut off from the chamber 23A, and the pilot chamber 23A and tank port 20A
The other oil passage 43B is connected to the end land 29B.
At the same time, it enters into the spring chamber 24, and communicates the pilot chamber 23B and the tank port 20B with a larger flow path area than when they are in the neutral position (a).

Furthermore, when the operating lever 5C is tilted in the direction of arrow B, the communication between the pilot chamber 23B and the tank port 20B via the oil passage 43B is cut off, and the communication between the pilot chamber 23A and the tank port 20A is disconnected via the oil passage 43A. Similarly, they communicate with each other with a large flow path area.

The switching valve 41 according to this embodiment has the configuration as described above, and its basic operation is not particularly different from that of the prior art.

However, in this embodiment, the spool sliding hole 12 is provided in the valve body 11.
Annular grooves 42A and 42B are formed at both ends of the end land 29A of the spool 25.

29B is formed with oval oil passages 43A and 43B extending a predetermined length in the axial direction, and in the neutral position, the annular groove 42 is formed.
Since the pilot chambers 23A, 23B and the tank ports 20A, 20B are communicated through the channels A, 42B, etc., the following effects can be obtained.

That is, by tilting the operating lever 5C shown in FIG.
A. When supplying water to the pilot chamber 23A via the check valve 10A and sliding the spool 25 to the right in the figure against the spring 32, the pilot chamber 23A becomes a tank port.
20A, and the pilot chamber 23B is connected to the oil passage 4.
Since it communicates with the tank port 20B via the tank port 3B, the oil in the pilot chamber 23B is transferred to the oil passage 43B and the tank port).
20B etc., and the switching valve 41 can be immediately switched from the neutral position (a) to the switching position (b), and the responsiveness at startup can be greatly improved.

When the operating lever 5C is returned to the neutral position,
Although the pilot pressure on the pilot chamber 23A side is released and the spool 25 is pushed toward the neutral position N (A) by the spring 32, the communication between the pilot chamber 23A and the tank port 20A via the oil passage 43A is cut off. Since it communicates with the tank 2 through the throttle valve 9A, etc., the throttle valve 9A gradually returns to the neutral position (a) by the throttling action of the throttle valve 9A, which alleviates the shock when the hydraulic motor etc. stops. can. Furthermore, when the operating lever 5C is tilted in the direction of arrow B, the pilot chamber 23B is cut off from the tank port 20B, and the biloft chamber 23A is communicated with the tank port 20A via the oil path 43A. can be immediately switched to the switching position (c), greatly improving responsiveness at startup.

Therefore, according to this embodiment, responsiveness at startup can be improved simply by forming the oil passages 43A, 43B in the end lands 29A, 29B, etc. of the spool 25.

Measures that have been taken in the past to improve responsiveness.

For example, measures such as increasing the pilot pressure from the sub-pump 6, making the pilot lines 7A and 7B thicker, installing an air bleed circuit in the pilot lines 7A and 7B, and installing a back pressure check valve are no longer necessary. Therefore, the performance of the switching valve 41 can be improved. Also, there is a problem with the response of the oil passage 43A.

43B etc., for example, the flow path area of the throttle valves 9A and 9B can be further reduced to allow the spool 25 to return to the neutral position (A) more slowly, thereby reducing the shock during stoppage. It has various effects, such as being able to more effectively alleviate the

In the above embodiment, the spool sliding hole 1 is provided in the valve body 11.
Annular groove 42A located at both ends of 2.

42B, but the annular groove 42A
, 42B are not necessarily provided, and when the annular grooves 42A, 42B are not provided, for example, as shown in FIG.
As in the first modification shown in FIG. 5, the end land 29A of the spool 25.

29B into the pilot chamber 23A and the spring chamber 24, and the oil passages 43A and 43B are extended in the axial direction.
The spring receiver 33' may have a stepped shape as shown.

Further, in the embodiment described above, the spring chamber 24 is provided in the lid member 22B, and the spool 25 is biased to the neutral position by the spring 32 disposed in the spring chamber 24. However, instead of this, Like the second modification shown in FIGS. 6 and 7, the lid member 22A.

Hydraulic pilot chambers 51A and 51 that also serve as spring chambers in 22B
B, and stoppers 52A, 52B that contact both ends of the spool 25 are arranged in the pilot chambers 51A, 51B, and the springs 53A, 5 are connected via the stoppers 52A, 52B.
3B may always urge the spool 25 to the neutral position.

〔Effect of the invention〕

As detailed above, according to the present invention, the spool is provided with an oil passage so that when pilot pressure is supplied to one hydraulic pilot chamber, the other hydraulic pilot chamber is communicated with the tank port. The oil in the other hydraulic pilot chamber can be directly discharged from the tank port to the tank, and the spool can be quickly slid by pilot pressure to instantly switch from the neutral position to the switching position.

The responsiveness at startup can be significantly improved. It was. It has various effects such as slowly returning the spool to the neutral position and alleviating the shock when it stops.

[Brief explanation of the drawing]

1 to 3 show embodiments of the present invention, FIG. 1 is a hydraulic circuit diagram, FIG. 2 is a vertical cross-sectional view of the directional control valve, and FIG. 3 is indicated by the ■-■ arrows in FIG. 4 and 5 show the first modification, FIG. 4 is a longitudinal sectional view of the directional switching valve, and FIG. 5 is a sectional view taken along the line v-v in FIG. 6 and 7 show a second modification, in which FIG. 6 is a longitudinal sectional view of the directional control valve, FIG. 7 is a sectional view in the direction indicated by the ■-■ arrow in FIG. Fig. 10 shows the prior art, Fig. 8 is a hydraulic circuit diagram, Fig. 9 is a vertical cross-sectional view of the directional control valve, Fig. 10 is a cross-sectional view along the direction of the arrow xx in Fig. 9, and Fig. 11 is a hydraulic circuit diagram showing another conventional technique. l... Hydraulic pump, 2... Tank, 3A, 3B.
...Main pipe, 5...Pilot valve, 5A, 5B...
Pressure reducing valve, 5C...operation lever, 6...sub pump,
7A. 7B... Pilot pipe line, 9A, 9B... Throttle valve, 10A, IOB... Check valve, 11... Valve body, 18... Pump port, 19.2OA, 20B...
-Tank port, 21A, 21B... Actuator side port, 22A, 22B... Lid member, 23A. 23B, 51A, 51B... Hydraulic pilot room, 24
...Spring chamber, 25...Spool, 32, 53A. 53B... Spring, 41... Hydraulic pilot type directional control valve, '42A, 42B... Annular groove, 43A, 43
B...Oil road. Figure 1

Claims (1)

[Claims] A valve body having a pump port, a tank port, and a pair of actuator side ports, and a valve body that is slidably inserted into the valve body, and when it is slid from a neutral position to a switching position,
A spool that communicates one actuator side port with the pump port and the other actuator side port of the pair of actuator side ports of the valve body with the tank port, and a spool that is always in a neutral position. a spring that presses the spool, and a pair of hydraulic pilot chambers that are provided in the valve body at both ends of the spool in the axial direction and that slide the scoop against the spring when pilot pressure is supplied from the outside. In a hydraulic pilot type directional control valve consisting of A hydraulic pilot type directional switching valve characterized in that the spool is provided with an oil passage so that one hydraulic pilot chamber is isolated from the tank port and the other hydraulic pilot chamber is communicated with the tank port.