JPS6018603A - Brake valve - Google Patents

Abstract

PURPOSE:To prevent abnormal surge pressure from occurring, by interconnecting a hydraulic chamber in a check valve, which makes oil flow from the hydraulic source side to the actuator side alone, to an actuator side oil passage via a throttle, while making a sectional area inside the hydraulic chamber larger than that of a valve seat. CONSTITUTION:When oil is fed to an oil passage 15A, if a directional control valve (selector) is set to a netural position, a counterbalance valve 8 comes in neutral as well, and thereby surge pressure is produced in both oil passages 13B and 26B at the actuator side but since a hydraulic chamber in a check valve 41B is interconnected to the oil passage 16B via a throttle 47B, it will not follow up immediately and then produced a pressure differential between the oil passage 26B and the hydraulic chamber 42B. In addition, there is a difference in a sectional area between the sliding part of a poppet valve body 43B and a valve seat 44B whereby a valve body 43 moves against a spring 45B, causing the pressure inside the oil passage 26B to be relieved to an oil passage 25B, thus the hydraulic chamber 42B is raised up with the throttle 47B, closing the valve seat 44B whereby braking takes place.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a brake valve installed in, for example, a hydraulic circuit that drives an inertial body using a hydraulic motor, and particularly to a brake valve installed in an inertial body drive circuit with a relatively small inertial mass. It concerns valves.

FIG. 1 shows a hydraulic circuit generally used in a traveling device of construction machinery as a hydraulic circuit for driving an inertial body using a hydraulic motor.

In the figure, reference numeral 1 indicates a hydraulic motor that drives a vehicle 2 of construction machinery as an inertial body, and the hydraulic motor 1 is provided with a pair of supply and discharge ports (9) A and B. )A
, B are each connected to a directional control valve 4 via a brake valve 3. By means of the directional switching valve 4, each supply/discharge port A, 13 of the hydraulic motor 1 is switchably connected to a hydraulic pressure input 5 and a tank 6 as a hydraulic pressure source.

Here, the brake valve 3 interposed between the hydraulic motor 1 and the directional switching valve 4 has a pair of oil passages 7A, 7B connecting between ports -A, B of the hydraulic motor 1 and the directional switching valve 4.
The counterbalance valve 8 is roughly composed of a counterbalance valve 8, a pair of check valves 9A, 9B, a pair of relief valves 10A, and an IOB, which are interposed in the middle of the oil passage 7A,
7B, and is configured to be switched depending on the pressure of the portion on the oil pressure source side of each of the west oil passages 7A and 7B.

When the directional control valve 4 is in the neutral position as shown in the figure, the connection between the hydraulic motor 1 side and the hydraulic power source side is cut off.
L, when it is switched to either the left or right operating position, the counterbalance valve 8 also switches accordingly, and the oil passage on the side connected to the tank 6 and the port of the hydraulic motor 1 among the oil passages 7A and 7B) A or B is connected. Further, the check valves 9A and 9B are provided in the middle of the oil passages 7A and 7B, respectively, and at a position closer to the hydraulic motor 1 than the counterbalance valve 8, and the directional control valve 4 is switched to prevent the oil from flowing. When either of the passages 7A and 7B is connected to the hydraulic pump 5, the hydraulic pump 5
Check valve 9A or 9 installed on the oil passage side connected to
The valve B is opened, and high pressure hydraulic oil can be supplied to port A or B of the hydraulic motor 1. Next, the relief valve 10A.

The check valves 9A and 9B of the oil passages 7A and 7B are respectively provided on the side closer to the hydraulic motor 1, and the relief valve 10A opens when the internal force relief set pressure of the oil passage 7A is exceeded. The relief valve 10 is designed to release high pressure hydraulic oil in the oil passage 7A to the oil passage 7B side.
B is arranged so that relief can be provided to the oil passage 7A side when the oil passage 7B exceeds the relief setting pressure.

The brake valve according to the prior art has the above-mentioned configuration, and when the vehicle 2 is stopped or dismounted, the hydraulic motor 1 is rotated by the inertia of the vehicle 2, for example, in the direction indicated by the arrow in the figure. When the oil is about to be drained, the oil passage 7B connected to port B, which is the discharge side, becomes under high pressure.
This pressure acts on the relief valve 10B, causing the relief valve 1
0B is opened to relieve oil to the oil passage 7A side, but the inertial energy of the vehicle 2 is converted into thermal energy generated when high-pressure hydraulic oil passes through this IJ leaf valve 10Bf, and this is used for braking action on the vehicle 2. is now being carried out.

By the way, if the vehicle 2 is a large construction machine with a large inertial mass, the inertial energy during braking will also be large.
In order to absorb such large inertial energy, the brake valve 3 is provided with a relief valve 10A.

Requires one with 10B installed inside. However, since the inertial energy during braking is also small in the running gear of medium to small construction machinery with a relatively small inertial mass, in order to simplify the structure of the brake valve, a relief valve 10A as shown in FIG. 2 is used. , 10B'i omitted L, counterbalance valve 8 and check valve 9A.

Generally, a brake valve 3' consisting of a brake valve 9B and a brake valve 3' is used.The specific structure of the brake valve 3' is as shown in FIG.

In the same figure, 11 is a casing that constitutes the main body of the brake valve 3', and the casing IIK is an oil pipe whose one end is connected to each port (A, H) of the hydraulic motor l, and whose other end is connected to piping 12A, 12B. Road 13A.

13B, and a pipe 14A whose one end is connected to the directional control valve 4.
, 14B is connected to the other end of the oil passage 15A.

15B is formed. And each oil passage 13A.

13B is an oil chamber 16A formed inside the casing 11.

16B, and the oil passages 15A and 15B are connected to the oil chamber 17.
It opens at A and 17B. Further, a spool 18 of the counterbalance valve 8 is slidably inserted into the casing 11. The spool 18 has oil chambers 16A, 1
Land 18A that communicates and blocks communication between 7A and oil chamber 16B,
Connects between 17B.

A blocking land 18B is provided. Both ends of the spool 18 face pilot chambers 19A and 19B formed in the casing 11, respectively.

Also, inside each of the members 20A and 19B are member members 20A that come into contact with each end surface of the spool 18.

20B is arranged, and each damper member 20A, 20B and...
e40t room 19A, 19B'i Character 7'2 to close
1A and 21B are interposed with screws 22A and 22B for assembling the spool 18 to the neutral position. Between the oil chambers 17A, 17B and the pilot chambers 19A, 19B, oil passages 23A, 2 are provided in the spool 18, respectively.
3B, and the damper part 'U'20A,
20B has narrow passages 24A and 24B (the narrow passage 24A is not shown in the drawing), respectively.

Next, 25A and 25B are oil chambers 17A, respectively.

17B, and 26A and 26B indicate oil passages communicating with oil passages 13A and 13B, respectively.
Each of the oil passages 25A, 26 persons, and oil passage 25B.

Check valves 9A and 9B are interposed between the oil passages 26 and 26, respectively.

It is designed to allow pressure oil to flow only from the 25B side to the oil passages 26A and 26B.

The check valves 9A and 9B each have one end slidably supported by a cap 27A and 27B screwed onto the casing 11, respectively. ! The poppet valve bodies 28A, 28B have springs 29A, 29B interposed between the poppet valve bodies 28A, 28B and the caps 27A, 27B. Oil line 26A, 2
It is configured such that it can be moved into and out of valve seats 30A and 30B formed at the periphery of the opening to 6B. here,
Oil passages 13A, 15A, 25A, 26A and oil chamber 16A
, 17A constitute an oil passage 7A together with piping 12A, 14A, and oil passages 13B, 15B, 25B.

26B and oil chamber 16B, 1711 are piping 12B.

Together with 14B, the oil passage 7B'i constitutes the oil passage 7B'i.

The relief valve according to the prior art has the above-mentioned configuration, and its operation will be explained first.

Now, assume that the directional switching valve 4 is switched from the neutral position to, for example, the switching position on the left in the figure. This oil passage 7A
The piping 14A constituting the oil passage 7Bi is connected to the hydraulic pump 5, and the piping 14B constituting the oil passage 7Bi is connected to the tank 6. For this purpose, high-pressure hydraulic oil supplied from the hydraulic pump 5 flows into the oil chamber 17A from the oil passage 15A.

Then, it flows from the core oil chamber 17A to the oil path 25A, and the check valve 9A1. (At the same time as the valve opens, this pressure also acts on the i4 oil chamber 1.9A via the oil passage 23A, displacing the spool 18 of the counterbalance valve 8 to the right in the figure. , 17B are in communication, oil path 1
3B and oil passage 15B are connected. As a result, oil pressure +1
? The pump 5 is connected to the port A of the hydraulic motor l via the oil passage 7A.
is connected to port B (d: tank 6) of the hydraulic motor 1, and the hydraulic motor 1 is driven to rotate in the direction of the arrow 211.!1, and the vehicle 2 is driven.

Next, when the directional control valve 4 is returned to the neutral position (6:) to stop the drive Q of the vehicle 2, the hydraulic cylinder 7''5 and the oil passage 15A
The connection between the oil passage 15A and the oil passage 15A is cut off, and the supply of high-pressure hydraulic oil to the oil passage 15A is stopped. For B, the check valve 9A closes, and the spool 18 of the counterbalance valve 8 also returns to the neutral position by the action of the spring 22B, and the hydraulic motor 1
The connection between port A and the hydraulic engine 5 is cut off, and the connection between port B and the tank 6 is also cut off, resulting in a circuit closed state. Here, the hydraulic motor 1 tries to rotate due to the inertial force of the vehicle 2, but the piping 12B1 and the oil passage 13B connected to the port B on the discharge side are in a state of oil lock, and the northern part is under high pressure. become. For this reason, the hydraulic motor 1 is kept in a high load state, and the inertial force of the vehicle 2 is expressed as a braking action.

As described above, when the counterbalance valve 8 returns to the neutral position, the circuit is suddenly closed, and a surge pressure is generated in the piping 12B1 and the oil passage 13B.

If the inertial mass of the vehicle 2 is relatively small, such as a medium or small-sized construction machine, this pressure will not increase significantly under normal usage conditions. However, vehicle 2
If the vehicle 2 is suddenly stopped when the vehicle 2 is disembarking, and the hydraulic oil in the circuit has a high viscosity, such as in a cold region, an extremely large surge pressure will be generated. However, the prior art described above is not equipped with a mechanism for absorbing such surge pressure, so this sword-to-surge pressure causes the hydraulic motor 1 and the brake valve 3' to
There are drawbacks such as damage to the equipment used.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a brake valve that can prevent abnormal surge pressure from occurring when a circuit close button is pressed.

In order to achieve the above object, the brake valve according to the present invention has a pair of check valves formed in a pair of oil passages formed in a casing for connecting an actuator and a hydraulic power source. Hydraulic chambers are formed to open respectively, a poppet valve body is slidably inserted into each hydraulic chamber, and an atto valve body is seated in each port so that each of the above-mentioned The oil passage is formed by a valve seat that defines an oil passage on the actuator side and an oil passage on the oil pressure source side, and a spring that biases the yJe pet valve body in the valve closing direction, and each of the hydraulic chambers is connected to the oil passage through the throttle passage. and connect each of the above-mentioned actuator side oil passages, and each of the above-mentioned +1? The bed valve body is characterized in that the cross-sectional area of the sliding portion in the hydraulic chamber is larger than the cross-sectional area of the valve seat.

Hereinafter, the present invention will be explained in detail based on FIGS. 4 and 5.

First, FIG. 4 shows a first embodiment of the present invention, and in FIG. 4, the same components as shown in the prior art are denoted by the same reference numerals, and the explanation thereof will be omitted.

However, 41A and 41B are oil passages 25A, respectively.

26A and oil passages 25B and 26B, each check valve 41A and 41B has hydraulic chambers 42A and 42B formed in the casing 11 so as to open into the oil passages 26A and 26B. Hydraulic chambers 42A, 42
Poppet valve body 4 with binuton slidably provided in B
3A, 43B, oil passages 25A, 26A, and oil passage 25
B, 26B, and poppet valve bodies 43A, 43
Valve seats 44A and 44B where B takes off from and arrives at the berth, and the ports 0, )
Valve body 43A.

43Bt - consists of springs 45A and 45B that bias in the valve closing direction, and the springs 45A and 45B are
A cap 46A and 46B that closes the cap B is interposed between the cap 46A and 46B. The poppet valve bodies 43A, 43B are provided with one or more restricting holes 47A, 47B that constantly communicate between the hydraulic chambers 42A, 42B and the oil passages 26A, 26B. The pressure of the oil passages 26A, 26B is introduced to the valves 43A, 26B, and this pressure acts on the poppet valve bodies 43A, 43B in the valve closing direction. On the other hand, the poppet valve bodies 43A and 43B are the hydraulic chamber 42A.

Diameter L of sliding part in 42B! is valve seat 44A.

44B has a diameter larger than L2, and the poppet valve bodies 43A, 43B contact the valve seats 44A, 44B (11
1! The + side is the oil passage 25A, 25B, which is the oil passage on the oil pressure source side of the oil passage 7A, on the inner peripheral side of the contact part with the valve seats 44A, 44B.
The pressure receiving surface and the valve seat 44A.

The outer peripheral side of the contact portion with 44B serves as a pressure receiving surface of oil passages 26A and 26B, which are actuator side oil passages, of oil passage 7B.

The brake valve configured as described above has its oil passages 13A and 13B connected to the piping 12A, as in the prior art.
, 12B, and the oil passage 15A.

15B is connected to the pipes 14A and 14B, forming part of a hydraulic circuit having the hydraulic motor 1, and braking the vehicle 20 is performed.

Therefore, when the directional control valve 4 is switched so that the oil passage 7A is connected to the hydraulic pump 5 and the oil passage 7B is connected to the tank 6, the hydraulic motor 1 sucks high-pressure hydraulic oil from its port A, and The return oil discharged from B is returned to the tank 6, and the vehicle 2 runs thereby. Even if the directional control valve 4 is returned to the neutral position in this state, it will be forcibly rotated by the hydraulic motor 1 due to the inertial force of the vehicle 2. There is no particular difference from the brake valve 3' according to the prior art described above in that the hydraulic oil is sealed, thereby absorbing the inertial force of the vehicle 2, and the braking action is performed.

However, if the vehicle 2 is suddenly stopped when the vehicle 2 is traveling in a dismounted state, or when the viscosity of the hydraulic oil flowing through the circuit is high such as in a cold region, water inside the piping 12B1 and the oil passage 13B may A momentary but extremely large surge pressure is generated. This pressure acts in the oil passage 26B, but since the oil pressure g42B communicates with the oil passage 26B through the throttle hole 47Bt, the oil pressure chamber 42B will not be affected by this even if the pressure in the oil passage 26B increases. The pressure will not rise immediately following this. For this reason, a differential pressure is generated between the oil passage 26B and the hydraulic chamber 42B, and the pressure inside this oil passage 20B is reduced to the poppet valve body 43B.
7J acts on the outer peripheral side of the contact portion with the valve seat 44B.
? The valve body 43B compresses the hydraulic oil in the hydraulic chamber 42B, moves away from the valve seat 44B, and relieves the pressure in the oil i&26B to the oil path 25B. For this reason, the surge pressure generated when the circuit is closed is reduced, and no inconvenience such as damage to equipment in the circuit occurs.

Then, the throttle hole 47B'l (through the oil passage 2
6B and the hydraulic chamber 42B are in communication, so the hydraulic chamber 42
B eventually becomes equal in pressure to the oil passage 26B.

Therefore, the poppet valve body 43B is seated on the valve seat 44B by the action of the spring 45B, and communication between the oil passage 25B and the oil passage 26B is again cut off.

For this reason, an oil lock occurs in the oil passage 13B of the piping 1281, and the braking operation of the vehicle 20 is performed.

On the other hand, when the directional control valve 4 is returned to the neutral position from the position where the port B side of the hydraulic motor 1 is connected to the hydraulic pump 5 and the boat A side is connected to the tank 6, the piping 12A1 oil Although surge pressure is generated on the side of the passage 13A, the check valve 41A operates in the same manner as described above, and the surge pressure is reduced.

Next, FIG. 1 shows a second embodiment of the present invention, and in this figure, the same components as those in FIG. However, in this embodiment, the hydraulic chambers 42A, 42B and the oil passages 13A, 13B are each called an oil passage 51A.

51B, and in the middle of each oil passage 51A, 51B is an oil passage 13A from the hydraulic chambers 42A, 42B side.

Check valve 5 that allows hydraulic oil to flow only toward the 13B side
2A and 52B'g are interposed.

By adopting such a configuration, the oil passage 15A or 15B is connected to the hydraulic cylinder f5, and the poppet valve bodies 43A, 43 constituting the check valves 41A, 41B'i
When the pressure of the hydraulic pump 5 acts on B, the hydraulic chamber 4
The hydraulic oil in 2A and 42B flows from the throttle holes 47A and 47B to the oil passage 26A.

26B and check valve 52A.

52Bi valve is opened and oil passages 51A and 51B are connected to oil passage 13A,
138, the responsiveness of the check valves 41A, 41B becomes better. On the other hand, since the hydraulic oil does not flow backward from the oil passages 13A, 13B toward the hydraulic chambers 42A, 42B, there is no problem with the surge pressure reduction effect.

In each of the above-described embodiments, the hydraulic motor 1 was described as one that drives the vehicle 2 of the construction machine as an inertial body, but the point is that it is a hydraulic circuit that drives an inertial body, and when the drive is stopped, the inertia of the inertial body is If it is necessary to absorb energy to perform a braking operation, it should be connected to the part on the hydraulic motor 1 side of the oil passages 7A and 7B defined by something other than the travel drive circuit of the construction machine mentioned above. For example, one end of the casing 11 opens to the hydraulic chambers 42A, 42B, and the other end opens to the oil passages 26A, 26B. Alternatively, it may be configured to open to the oil passages 13A, 13B.

As explained above, the brake valve according to the present invention is configured such that the check valve that allows the flow of hydraulic oil only from the hydraulic source side to the actuator side has a relief function that reduces the height pressure. It is possible to prevent abnormal air pressure from occurring when the circuit is closed, and it is possible to prevent damage to various devices constituting the circuit, such as a hydraulic motor, a counterbalance valve, and a check valve. Furthermore, by fully adjusting the flow path area of the throttle hole provided in the check valve, it can also be used as a brake valve in a drive circuit for an inertial body having a relatively large inertial mass.

[Brief explanation of the drawing]

Figures 1 to 3 show the prior art, Figure 1 is a hydraulic circuit diagram using a brake valve, Figure 2 is a hydraulic circuit diagram showing another prior art, and Figure 3 is the brake valve shown in Figure 2. Longitudinal cross-sectional view of
8g4 is a vertical sectional view of a brake valve showing a first embodiment of the invention, and FIG. 5 is a longitudinal sectional view of a brake valve showing a second embodiment of the invention. 1...Hydraulic motor, 5...Hydraulic pump, 7A, 7B
26A, 26n, sxi, sxB... oil path, 1B...
・Susol, 41A, 41B...Check valve, 42A
. 42B...Hydraulic chamber, 43A, 4jB...PoJ,
) Valve body, 44A, 44B...Valve seat, 45A, 45B...
...Spring, 47A, 47B...Diaper hole, 52A, 52
B...Check valve O Fig. 1

Claims (2)

[Claims] (1) A pair of oil passages are formed in the casing, one end of which is connected to each supply/discharge port of the actuator, and the other end of which is switchably connected to a hydraulic power source, and each oil passage has a counter on the hydraulic power source side. In the brake valve, a balance valve is provided and a pair of check valves are interposed on the actuator side to allow flow of hydraulic oil only from the hydraulic pressure source side toward the actuator side. A hydraulic chamber formed to open into an oil passage, a poppet valve element slidably inserted into each oil pressure chamber, and dust deposited on each poppet valve element to prevent the oil passages from leaking. A valve seat defined by an actuator side oil passage and a hydraulic source side oil passage, and a spring that biases the poppet valve body in a valve closing direction,
Each of the hydraulic chambers is connected to each of the actuator side oil passages via a throttle passage, and each of the poppet valve bodies is arranged such that the cross-sectional area of the sliding part in the hydraulic chamber is larger than the cross-sectional area of the valve seat. A brake valve characterized by forming and forming. (2) A patent characterized in that each of the hydraulic chambers and each of the actuator-side oil passages are connected via a check valve that allows hydraulic oil to flow only from each of the hydraulic chambers to the actuator-side oil passage. A brake valve according to claim (1).