JPH0744802Y2 - Pressure control valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a pressure control valve used as, for example, a counterbalance valve, a brake valve, or the like.

[Prior art]

Generally, with hydraulic actuators such as hydraulic motors and cylinders, such as hydraulic excavators and hydraulic cranes,
Machines that are driven to run or turn are subject to extremely large inertial loads when they stop running or turn. Therefore, a brake valve is provided in the hydraulic drive circuit, and the inertia load as described above is effectively absorbed by the brake valve. Therefore, the brake valve is composed of a counter balance valve provided between the hydraulic source and the hydraulic actuator, and a pair of overload relief valves arranged on the hydraulic actuator side of the counter balance valve. And
The counter balance valve rapidly shuts off the low pressure side supply / discharge passage to the hydraulic actuator at the same time when the supply of the pressure oil from the hydraulic source is cut off, and stops the rotation or stroke of the hydraulic actuator to quickly generate the brake pressure. It is designed to prompt you.

As a pressure control valve used for the counter balance valve or the brake valve having the above-mentioned function, the oil groove communicating with the actuator side port is located axially outside and the oil groove communicating with the hydraulic side port is located axially inside. There are two types, the oil groove communicating with the actuator side port is located on the inner side in the axial direction, and the oil groove communicating with the hydraulic side port is located on the outer side in the axial direction. The ones shown in FIGS. 4 and 5 are known.

That is, FIG. 4 is a hydraulic circuit diagram including a brake valve.
Is a hydraulic motor, 2 is an inertial body driven by the hydraulic motor 1, supply / discharge ports A and B of the hydraulic motor 1 are connected to oil pipes 3A and 3B, and the oil pipes 3A and 3B are connected to the brake valve 4 ,
It is connected to the direction switching valve 5, and the inflow side of the direction switching valve 5 is switchably connected to the hydraulic pump 6 and the tank 7.

Here, the brake valve 4 is composed of a pair of overload relief valves 8A, 8B provided between the oil pipes 3A, 3B and a counter balance valve 9, and the counter balance valve 9 is provided for each oil pipe 3A, 3B. Check valves 10A and 10B provided respectively in the middle of 3B to allow the flow of pressure oil only from the hydraulic pump 6 to the hydraulic motor 1 side, and the oil passage is opened only when the pressure oil supplied from the hydraulic pump 6 is sufficient. It is composed of a pressure control valve 11 that rapidly shuts off the flow path when the switching valve 5 is shut off.

Next, the pressure control valve 11 described above will be specifically described with reference to FIG.

Reference numeral 12 denotes a valve body of the pressure control valve 11, and the valve body 12 has hydraulic source side ports 13A and 13B connected to the direction switching valve 5 and a hydraulic motor 1.
Actuator-side ports 14A and 14B that are connected to the above are formed. Further, a spool sliding hole 15 is bored in the valve body 12 in the axial direction, and oil grooves 16A, 16B communicating with the hydraulic pressure source side ports 13A, 13B are formed in the spool sliding hole 15 at a predetermined distance. Oil grooves 17A, 17B communicating with the actuator-side ports 14A, 14B are formed on both axial sides of the oil grooves 16A, 16B, respectively, and the oil grooves 17A, 17B communicating with the actuator-side ports 14A, 14B are formed. Is an oil groove 16A, which communicates with the hydraulic source side ports 13A, 13B.
It is located axially outside the spool sliding hole 15 with respect to 16B. In addition, the valve body 12 has a spool sliding hole.
Oil chambers 19A, 19B are formed at both ends of 15 and closed by lids 18A, 18B.

Reference numeral 20 is a spool slidably fitted in the spool sliding hole 15, and the spool 20 is a land 21 that constantly closes between the oil grooves 16A and 16B and both sides of the land 21. 16A, 17
A land 22A that communicates and blocks A through the notch portion 22A ₁ and a land 22B that communicates and blocks the oil grooves 16B and 17B through the notch portion 22B ₁ , and are formed at both ends of the spool 20, respectively. A land 23A that always shuts off between the oil groove 17A and the oil chamber 19A, and a land 23B that always shuts off between the oil groove 17B and the oil chamber 19B are provided.

24A and 24B are stoppers provided in the oil chambers 19A and 19B.The stoppers 24A and 24B contact the lids 18A and 18B to regulate the stroke when the spool 20 slides to the full stroke position. It has become. 25A and 25B are the stopper 2
Centering springs stretched between 4A, 24B and the lids 18A, 18B, respectively. The springs 25A, 25B quickly move the spool 20 to the neutral position when the directional control valve 5 is in the neutral position. The state shown in the drawing is maintained.

Further, 26A and 26B are throttle passages formed between the lands 21 and 22A and between the lands 21 and 22B and formed in the radial direction of the spool 20 for preventing hunting, and 27A and 27B are from the throttle passages 26A and 26B to the spool 20. The oil passage formed in the axial direction toward the end face of the 28A,
Reference numerals 28B denote oil passages formed in the axial directions of the stoppers 24A, 24B so as to communicate with the oil passages 27A, 27B, respectively. Pressure oil from the hydraulic pressure source side ports 13A, 13B is restricted by the throttle passages 26A, 26B, 27A, 27B
The oil is supplied as a pilot pressure to the oil chambers 19A, 19B via the oil passages 28A, 28B, and the spool 20 is made to stroke.

The pressure control valve 11 according to the prior art is constructed as described above. The operation of the brake valve 4 when the pressure control valve 11 is incorporated in the hydraulic circuit of FIG. 4 will be described.

Now, suppose that the direction switching valve 5 is switched from the neutral position (a) to the left switching position (b). As a result, the hydraulic pump 6
The high pressure oil from is opened via the oil pipe 3A to the check valve 10A, and is supplied from the hydraulic pressure source side port 13A of the pressure control valve 11 to the oil groove 16A. As a result, the pressure oil from the oil groove 16A acts on the oil chamber 19A via the throttle passage 26A and the oil passages 27A, 28A, and the spool 20 is resisted against the spring 25B to a position where the stopper 24B abuts the lid 18B. Stroke to the right in the middle, and oil grooves 16B, 17
Communicate between B via land 22B. At this time, the oil chamber 19B
While the pressure oil inside is throttled by the throttle passage 26B, the hydraulic pressure source side port 1
By flowing out to 3B, the spool 20 is provided with a cushioning effect at the time of valve opening, so that the spool 20 can be stably controlled to open. Thus, the hydraulic pump 6 communicates with the supply / discharge port A of the hydraulic motor 1 via the direction switching valve 5, the oil pipe 3A, and the check valve 10A, and the supply / discharge port B of the hydraulic motor 1 has the oil pipe 3B and the pressure control valve. 11, communicating with the tank 7 through the direction switching valve 5, the hydraulic motor 1 connects the inertial body 2 to the fourth
Rotate in the direction of the arrow in the figure.

Next, when the directional control valve 5 is returned to the neutral position (a) to stop the rotation of the inertial body 2, the supply of high pressure oil from the hydraulic pump 6 is cut off, the check valve 10A is closed, and the pressure control is performed. The supply of high pressure oil to the valve 11 is stopped. Therefore, the spool 20 returns to the neutral position by the spring force of the spring 25B, and shuts off between the oil grooves 16B and 17B. As a result, the connection between the supply / discharge ports A and B of the hydraulic motor 1 and the hydraulic pump 6 and the tank 7 is cut off by the check valves 10A and 10B and the pressure control valve 11, and the circuit is closed. The hydraulic motor 1 tries to continue rotating in the direction of the arrow by the inertial force of the inertial body 2.
As a result, the supply / discharge port B on the discharge side of the hydraulic motor 1,
The oil pipe 3B has a high pressure, and this pressure acts on the overload relief valve 8B to open it and relieve the pressure oil to the oil pipe 3A side, but the inertia energy of the inertial body 2 is due to the pressure oil overload relief. The heat energy generated when flowing through the valve 8B is converted into a braking effect on the inertial body 2.

Further, when the inertial body 2 is driven while receiving a negative load, for example, when the hydraulic excavator is driven to travel, when going down a slope, the directional control valve 5 moves from the neutral position (a) to the left switching position (ro). ), But the spool 20 of the counterbalance valve 9 is at an intermediate position between the neutral position and the maximum stroke position.

At this time, if the spool 20 moves to the right excessively due to inertia, the oil groove
Since the opening area of the oil passage from the oil groove 17B to the oil groove 16B is increased, the brake pressure is reduced, and the hydraulic excavator 11 accelerates or escapes on a slope. In addition, as a result, the rotation speed of the hydraulic motor 1 increases,
When the amount of supplied oil is insufficient and the driving pressure drops, the spool 20 moves left due to the spring 25B, and the oil passage opening area from the oil groove 17B to the oil groove 16B decreases, so the brake pressure increases and the hydraulic excavator does not decelerate. Stop. Then, the driving pressure rises and the spool starts moving to the right. By repeating this, a so-called hunting phenomenon occurs.

Therefore, the spool 20 is provided with throttle passages 26A and 26B,
By using the hydraulic chambers 19A and 19B as damper chambers, excessive stroke is suppressed when the spool 20 moves from the neutral position toward the maximum stroke position, and hunting is prevented.

[Problems to be solved by the device]

However, in the above-mentioned conventional technique, for example, the spool 20 is fully stroked to the right in FIG. 5 and the directional control valve 5 is set to the neutral position (a) with the stopper 24B abutting the lid 18B. When returned, there is a problem that the spool 20 of the pressure control valve 11 cannot be quickly returned to the neutral position in conjunction with this. That is, when the direction switching valve 5 is returned to the neutral position (a) and the supply of pressure oil from the hydraulic pump 6 to the pressure control valve 11 is cut off, the spool 20 tries to return to the neutral position by the spring 25B. The pressure oil in the chamber 19A (including the pressure oil sealed between the stopper 24A and the end surface of the spool 20 on the land 23A side) is given a large throttling action by the throttle passage 26A.
It cannot be swiftly discharged toward 13A, which delays the return of the spool 20 to the neutral position.

For this reason, in the prior art, the spool 20 does not quickly return to the neutral position in conjunction with the directional control valve 5, so that the hydraulic motor 1
In addition to the delay of the stop of the inertial body 2 and the supply of the pressure oil from the hydraulic pump 6, the hydraulic motor 1 is stopped.
Return oil from the actuator side port of pressure control valve 11
The oil is discharged from 14B (14A) toward the hydraulic pressure source side port 13B (13A), causing a shortage of hydraulic oil in the oil pipes 3A, 3B between the hydraulic motor 1 and the pressure control valve 11, causing cavitation. Therefore, there is a problem that the hydraulic motor 1 and the like are easily damaged.

The present invention has been made in view of the above-mentioned problems of the prior art. The present invention enables the spool to be quickly returned from the full stroke position to the neutral position, and effectively suppresses the occurrence of cavitation. A pressure control valve is provided.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, the present invention has a hydraulic pressure source side port and an actuator side port that are axially separated from each other in a spool sliding hole, and an oil groove communicating with the actuator side port has a hydraulic pressure source side port. A valve body located axially outside of the oil groove communicating with the oil groove, a spool having a land inserted into the spool sliding hole of the valve body, and having a land for communicating and blocking the oil grooves, A pair of oil chambers formed in the valve body at both axial ends, a throttle passage formed in the spool for communicating the oil chambers with the hydraulic pressure source side port, It is intended for a pressure control valve of a type provided in an oil chamber and comprising a pair of springs for constantly biasing the spool to a neutral position.

The feature of the means adopted by the present invention is that one end side of the valve body is opened to the hydraulic pressure source side port, and the other end side is located between each oil chamber and an oil groove communicating with the actuator side port. A pair of oil passages that open in the spool sliding hole are provided, and the spool sliding hole is provided between each oil chamber and the hydraulic pressure source side port until the spool returns to a neutral position by a predetermined dimension from the full stroke position. It is configured to communicate with each other through the oil passages.

[Action]

With the above configuration, when the spool is returned to the neutral position by the spring in the state where the spool is stroked to one oil chamber side of the pair of oil chambers, the spool moves from the full stroke position to the neutral position. The spool slide hole communicates with the hydraulic pressure source side port via the oil passage until it returns to the position by the predetermined size, and the pressure passage on the other oil chamber side opens the spool slide hole in the meantime. It is possible to quickly flow out from the port toward the hydraulic pressure source side port, and to speed up the return speed of the spool to the neutral position.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. In the embodiment, the same components as those of the prior art shown in FIGS. 4 and 5 described above are designated by the same reference numerals, and the description thereof will be omitted.

1 and 2 show a first embodiment of the present invention.

In the figure, 31A and 31B have one end open to the hydraulic pressure source side ports 13A and 13B, and the other end side to the oil groove 17 of the actuator side ports 14A and 14B.
Located between A and 17B and oil chambers 19A and 19B, spool sliding hole 15
1 shows a pair of oil passages bored in the valve body 12 so as to open inside, and the oil passages 31A and 31B have an oil chamber 19A as illustrated in FIG. 1 when the full stroke amount of the spool 20 is l. , 19B
It opens into the spool sliding hole 15 at a position separated from the end faces of the (stoppers 24A, 24B) by a predetermined dimension of 2/3 l, and the spool 20
When a stroke of 2/3 l or more from the neutral position to the left and right has reached a predetermined dimension, the hydraulic pressure source side ports 13A, 13B and the oil chambers 19A, 19B are made to communicate with each other via the spool sliding holes 15. There is.

The pressure control valve according to the present embodiment has the above-described structure, and its basic operation is not significantly different from that of the prior art.

Therefore, in this embodiment, the actuator side ports 14A and 14B are
Located between the oil grooves 17A, 17B communicating with the oil chambers and the oil chambers 19A, 19B, and a pair of oil passages 31A, 31B opening from the hydraulic pressure source side ports 13A, 13B to the spool sliding holes 15 are provided in the valve body 12. Because it was formed
The spool 20 moves to the left and right from the neutral position.
When the stroke is 3 l or more, the hydraulic pressure source side ports 13A, 13B
And the oil chambers 19A, 19B communicate with each other through the oil passages 31A, 31B, and the two passages communicate with each other by the oil passages 31A, 31B in addition to the throttle passages 26A, 26B. The area sharply increases as shown by the characteristic line 32 shown by the solid line in FIG.

On the other hand, in the case of the prior art that does not have the oil passages 31A and 31B, the hydraulic pressure source side ports 13A and 13B and the oil chambers 19A and 19B communicate with each other only via the throttle passages 26A and 26B. The flow passage area between the two is always constant along the characteristic line 33 shown by the dotted line in FIG. 2, and when the spool 20 strokes beyond the predetermined dimension 2 / 3l to the full stroke l position. The flow passage area cannot be increased as indicated by the characteristic line 32, and the dimension 20 returns from the full stroke position to the neutral position at a relatively slow speed.

Thus, according to the present embodiment, for example, the spool 20 is fully stroked to the right in FIG. 1, and the end surface 23A ₁ of the spool 20 on the land 23A side is indicated by a two-dot chain line in FIG. When the directional control valve 5 is returned to the neutral position (a) and the spool 20 is returned to the neutral position by the spring 25B in the state of maximum displacement to the position of the stroke l, the inside of the oil chamber 19A is in the hydraulic pressure source side port 13A. And in addition to the throttle passage 26A and the oil passage 31A,
Since the flow passage area is greatly increased as shown by the characteristic line 32 in FIG. 2, the spool 20 rapidly returns from the position of the full stroke l to the position of the predetermined dimension 2 / 3l, and the pressure on the oil chamber 19A side is reduced. Oil can quickly flow out into the hydraulic pressure source side port 13A via the oil passage 31A, and the spool 20 can be returned to the neutral position at a high speed.

Therefore, by returning the spool 20 to the neutral position at a high speed in conjunction with the direction switching valve 5, the stop operation of the hydraulic motor 1 and the inertial body 2 can be speeded up, and the return oil from the hydraulic motor 1 Actuator side port 14B (1
It is possible to prevent a large amount of hydraulic oil from being discharged from the 4A) side toward the hydraulic power source side port 13B (13A), resulting in a shortage of hydraulic oil as described in the prior art, suppressing the occurrence of cavitation, and damaging the hydraulic motor 1 etc. It is possible to solve such problems as being caused.

Next, FIG. 3 shows a second embodiment of the present invention. The feature of this embodiment is that the spool slide is separated from the end faces of the oil chambers 19A, 19B (stoppers 24A, 24B) by a predetermined dimension 2 / 3l. Annular grooves 41A, 41B are formed at both ends of the moving hole 15, and throttle passages 42A, 42B are bored between the annular grooves 41A, 41B and the hydraulic pressure source side ports 13A, 13B, and the throttle passages 42A, 42B are formed. And the annular grooves 41A, 41B open one end to the hydraulic pressure source side ports 13A, 13B and the other end side between the oil grooves 17A, 17B of the actuator side ports 14A, 14B and the oil chambers 19A, 19B. This is because a pair of oil passages 43A and 43B that open into the inside of 15 are configured.

Thus, in this embodiment configured as described above, substantially the same effects as those of the first embodiment can be obtained, but particularly in this embodiment, the spool 20 is moved to the full stroke l.
When returning from the position of to the position of the specified size 2 / 3l, the oil chamber 19
A throttle passage between A (19B) and hydraulic source side port 13A (13B)
26A, 42A (26B, 42B) are interlocked, and the throttle passage 42A (4
2B) makes it possible to adjust the return speed of the spool 20 by increasing the flow passage area between them.

In each of the above embodiments, when the full stroke amount of the spool 20 is 1, the pair of oil passages 31A, 31B (annular grooves 41A, 4
1B) has been described as being opened at a position separated from the end faces of the oil chambers 19A, 19B by a predetermined dimension of 2 / 3l.
The opening position of the (annular grooves 41A, 41B) is not limited to this, and the oil groove 17 interlocking with the actuator side ports 14A, 14B is used.
It may be located between A and 17B and the oil chambers 19A and 19B and opened.

[Effect of device]

As described in detail above, according to the present invention, one end of the valve body is opened to the hydraulic pressure source side port, and the other end side is located between each oil chamber and the oil groove interlocking with the actuator side port, so that the spool slides. Since the pair of oil passages opening to the holes are provided, when the spool is returned from the full stroke position to the neutral position by the spring, until the spool returns from the full stroke position to the neutral position by a predetermined dimension, Not only can the speed of return of the spool be increased by letting the pressure oil in the oil chamber flow out into the port on the hydraulic pressure source side through the oil passage together with the throttle passage, and the stopping speed of the actuator and inertial body can be increased. Thus, it is possible to effectively suppress the occurrence of cavitation due to insufficient hydraulic oil.

[Brief description of drawings]

1 and 2 show a first embodiment of the present invention, FIG. 1 is a longitudinal sectional view of a pressure control valve, and FIG. 2 is a characteristic diagram showing a relationship between a stroke amount of a spool and a flow passage area. FIG. 3 is a longitudinal sectional view of a pressure control valve showing a second embodiment, FIGS. 4 and 5 show a prior art, FIG. 4 is a hydraulic circuit diagram, and FIG. 5 is a longitudinal section of the pressure control valve. It is a side view. 1 ... Hydraulic motor (actuator), 2 ... Inertial body, 3A, 3
B ... Oil pipe, 5 ... Direction switching valve, 6 ... Hydraulic pump, 11 ... Pressure control valve, 12 ... Valve body, 13A, 13B ... Hydraulic source side port, 14
A, 14B ... Actuator side port, 15 ... Spool sliding hole, 16A, 16B, 17A, 17B ... Oil groove, 19A, 19B ... Oil chamber, 20 ... Spool, 21, 22A, 22B, 23A, 23B ... Land, 24A , 24B ... Stopper, 25A, 25B ... Spring, 26A, 26B ... Throttle passage, 31A, 31B, 43A,
43B ... Oil passage, 41A, 41B ... Annular groove, 42A, 42B ... Throttle passage.

Claims (1)

[Scope of utility model registration request] Claim: What is claimed is: 1. A spool sliding hole has an oil pressure source side port and an actuator side port which are separated from each other in the axial direction, and the oil groove communicating with the actuator side port is more axial than the oil groove communicating with the oil pressure source side port. A valve body located outside in the direction,
A spool having a land that is fitted into a spool sliding hole of the valve body and that communicates and blocks between the oil grooves, and a pair formed on the valve body at both axial ends of the spool. Oil chambers, a throttle passage formed in the spool for communicating the oil chambers with the hydraulic pressure source side port, and a pair of springs provided in the oil chambers for constantly biasing the spools to the neutral position. In the pressure control valve consisting of, one end side of the valve body opens to the hydraulic pressure source side port,
A pair of oil passages, each of which has the other end located between the oil chamber and an oil groove communicating with the actuator-side port and opens into the spool sliding hole, is provided so that the spool moves from the full stroke position to the neutral position. A pressure control valve, characterized in that the respective oil chambers and the hydraulic pressure source side port are communicated with each other through the spool sliding holes and the respective oil passages until they return to a stroke position of a predetermined dimension.