JPS6231681Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a brake valve equipped with a crossover type relief valve that controls the inertial load of an inertial body.

(Prior Art) In this type of brake valve, if the set pressure of the relief valve is high, a large shock occurs when the actuator is activated or when braking is started. Therefore, when the set pressure of the relief valve is lowered, there is a problem that the torque of the actuator decreases too much and its holding ability decreases.

In order to solve this problem, the applicant has
We have already provided the brake valve described in Publication No. 86069 (Japanese Patent Application No. 153391/1986).

This brake valve is separate from the relief valve.
An adjustment chamber containing a piston is provided, and the volume of the adjustment chamber is expanded by moving the piston, thereby substantially expanding the volume of the spring chamber of the relief valve. By substantially expanding the volume of the spring chamber in this manner, the circuit pressure at the time of starting the actuator or starting braking can be maintained at a low pressure, thereby making it possible to prevent the occurrence of a shock.

(Problems to be Solved by the Present Invention) Even with the brake valve configured as described above, the purpose of alleviating the shock at the time of startup or the start of braking can be achieved.

However, in this conventional brake valve, since the adjustment chamber must be provided separately from the relief valve, the brake valve itself has the disadvantage of increasing in size.

The purpose of this invention is to provide a brake valve that eliminates a drop in actuator torque, sufficiently performs a shockless function, and can be made smaller.

(Means for solving the problem) In order to achieve the above object, this invention is configured as follows.

A counterbalance valve is connected to the upstream side of a pair of main passages formed in the casing, a motor is connected to the downstream side, and a pair of crossover type relief valves are provided, and the inflow sides of the relief valves are connected to the respective main passages. and its outflow side,
The relief valve is connected to the main passage on the opposite side to the inflow side, and an orifice is formed in this relief valve, and the pressure oil on the inflow side is introduced into the spring chamber through this orifice. In a brake valve operated by a pressure receiving area difference, an adjustment piston is provided around the spring chamber of the crossover type relief valve, and a space defined on one side of the adjustment piston is connected to an inflow of the relief valve with which the spring chamber communicates. The adjustment chamber divided on the other side is communicated with a main passage other than the main passage connected to the other side, and the adjustment piston moves toward the space, thereby adjusting the spring chamber. It is configured to substantially expand the volume.

(Operation of the present invention) When the pressure oil in the main passage on the high pressure side acts on the adjustment piston, the adjustment piston moves and expands the volume of the adjustment chamber. Increasing the volume of the adjustment chamber in this way is equivalent to substantially expanding the volume of the spring chamber communicating with the adjustment chamber.

In the process of expanding the volume of the adjustment chamber, a flow occurs in the orifice formed in the relief valve, and a pressure loss occurs before and after the orifice. In other words, a pressure difference is generated before and after the orifice, and the relief valve opens due to the action of this pressure difference.

Also, when the adjustment piston reaches full stroke,
Since the volume of the spring chamber is kept constant, no flow occurs in the orifice, and there is no differential pressure across the orifice. Therefore, after the adjustment piston has made a full stroke, the relief valve opens due to the difference in pressure receiving area before and after the orifice.

Then, when pressure oil in a passage other than the main passage connecting the inflow side of the relief valve with which the spring chamber communicates acts on the adjustment piston, the adjustment piston moves to the initial position.

(Effects of the present invention) According to the brake valve of this invention, an adjustment piston that substantially expands the volume of the spring chamber of the crossover type relief valve is provided around the spring chamber, so the brake valve can be miniaturized. sell.

(Embodiments of the present invention) This will be described below with respect to each of the illustrated embodiments.

In the first embodiment shown in FIGS. 1 and 2, a spool 1 having a counterbalance function and crossover type relief valves 2 and 3 are built into a casing a.

A switching valve 4 is connected to ports P1 and P2 of the casing a, and depending on the position of the switching valve 4, either port P1 or P2 communicates with the pump 5, and the other communicates with the tank 6. I'm in a relationship.

For example, when the switching valve 4 is switched from the illustrated neutral position to the left position, the port P1 communicates with the pump 5 and the port P2 communicates with the tank 6. Therefore, the pressure oil sent from the pump 5 pushes open the check valve 7 built into the spool 1, and is supplied to the actuator m from the port M1 via the main passage 61. At the same time, the pressure of the pump 5 is introduced into the chamber 8, so that the spool 1 is moved to the left in the drawing by this pressure action, and the annular groove 9 of the spool 1 is brought into communication with the port M2.

Therefore, the return oil of the actuator m is
Passing through the main passage 62, port M2 and port P
2 and returned to tank 6.

When the switching valve 4 is switched from this state to the neutral position shown, the pump 5 is communicated with the tank 10 and the port P1 is also communicated with the tank 6. When the port P1 communicates with the tank 6, the pressure in the chamber 8 decreases, the spool 1 returns to its original position (the position shown), and communication between the port M2 and the annular groove 9 is cut off.
At this time, the actuator performs a pump function due to inertia, so the main passage 62 side communicating with the port M2 becomes high pressure, and this high pressure acts on the relief valve 2 via the branch passage 11. When the inertial energy of the actuator, that is, the high-pressure oil acts on the relief valve 2 in this way, the relief valve 2 gradually opens, causing the high-pressure oil on the main passage 62 side to flow from the branch passage 11 to the main passage 61 side. When high-pressure oil passes through the relief valve 2 in this manner, inertial energy is converted into thermal energy of the oil, which applies a brake to the actuator m.

Furthermore, when the switching valve 4 is switched to the right position shown in the figure, the port P2 is connected to the pump 5, and the port P1 is connected to the pump 5.
are connected to the tank 6, respectively. and pump 5
The pressure oil flows in the opposite direction to the above and operates the actuator in the opposite direction, and each component in the flow path corresponds to the above-mentioned elements. That is, in the figure, reference numeral 13 is a check valve built into the spool 1, 14 is a chamber communicating with the port P2, and 15 is an annular groove formed in the spool 1.

As mentioned above, the relief valves 2 and 3 that convert inertial energy into thermal energy have their pressure connection ports 1
6 and 17 are communicated with the branch passages 11 and 12. These pressure connections 16 and 17 are connected to poppet 1.
8 and 19, and there is a poppet 1 on the outer periphery that roughly corresponds to the seat part.
Holding members 20 and 2 that slidably hold 8 and 19
I believe in 1. And this holding member 20,
21 includes a relief housing 24 that forms the spring chambers 22 and 23 of the relief valves 2 and 3;
I am holding on to 25. Springs 26, 27 are interposed within the relief housings 24, 25 to normally bring the poppets 18, 19 into pressure contact with the seats at the pressure connection positions 16, 17.

The pressure receiving areas _S2 of the spring chambers 22 and 23 are made smaller than the pressure receiving areas _S1 of the poppets 18 and 19 facing the seat portion.

Relief housing 24, 2 made as above
Adjustment pistons 28 and 29 are slidably engaged with the outer peripheries of the adjustment pistons 28 and 29, and one side of the adjustment pistons 28 and 29 are used as spaces 31 and 32, and the other side is used as adjustment chambers 63 and 64.

The spaces 31 and 32 are orifices 33 and 34
The adjusting chambers 63, 64 on the opposite side of the spaces 31, 32 communicate with the spring chambers 22, 23 through small holes 35, 36, respectively.

Reference numerals 37 and 38 in the figure are adjustment screws,
This is for adjusting the spring loads of the springs 26 and 27, that is, the set pressures of the relief valves 2 and 3.

However, when the actuator is driven by switching the switching valve 4 from the neutral position shown in the figure to the left position as described above, pressure oil flows from the port M1 into the main passage 61 and the branch passage 12 communicating with the main passage 61. be introduced. This pressure oil flows into the spring chamber 23 of the relief valve 3 via an orifice 39 formed in the poppet 19, and at the same time acts on the adjusting piston 29 through a small hole 36.

When the pressure oil acts on the adjustment piston 29 as described above, the adjustment piston 29 moves to the right in FIG. 2 while pushing out the oil in the space 32 from the orifice 34. When the adjustment piston 29 moves in this manner, the adjustment chamber 64 is expanded, and the volume of the spring chamber 23 is also substantially expanded by the expanded volume.

While the adjustment piston 29 is moving, the hydraulic oil in the spring chamber 23 is absorbed into the adjustment chamber 6.
4, a pressure difference is generated across the orifice 39 formed in the poppet 19. Since the influence of this differential pressure and the difference between the pressure receiving areas S ₁ and S ₂ act synergistically, the relief valve 3 opens at a low pressure. In other words, the relief valve 3 functions as a low pressure relief valve at this time.

As mentioned above, when starting actuator m,
Since the relief valve 3 functions as a low pressure relief valve, the shock upon activation is alleviated.

Also, when the adjustment piston 29 has completely moved,
The pressure on the pressure connection port 17 side and the pressure on the spring chamber 23 side become equal. For this purpose, the pressure connection port 17 side of the poppet 19 and the spring chamber 2
Since the set pressure is determined by the difference between the pressure receiving areas S ₁ and S ₂ and the spring load of the spring 27, the relief valve 3 functions as a high pressure relief valve. Therefore, after the actuator m is activated, its torque does not decrease.

Note that the pressure in the main passage 61, which is the high pressure side, is also guided to the space 31 through the passage 65, and acts on the adjustment piston 28 of the relief valve 2 as well. Due to this pressure action, the adjustment piston 28 moves, and the hydraulic oil in the adjustment chamber 63 is transferred to the relief valve 2.
The adjustment piston is pushed out to the low pressure side main passage 62 through the spring chamber 22 and orifice 33, and the adjustment piston is set at the initial position of movement. In other words, when the actuator is driven,
The relief valve whose inlet is connected to the main passage on the low pressure side always has its adjusting piston set at the initial position.

Next, when the switching valve 4 is returned to the neutral position shown in the figure while the actuator m is being driven, the chamber 8 is moved to the tank 6.
, so spool 1 also returns to the neutral position,
Port M1 communicating with the main passage 61 and port M2 communicating with the main passage are closed. Port M
Even when M1 and M2 are closed, the actuator m rotates due to its inertia and performs a pumping action, resulting in high pressure on the main passage 62 side.

When the main passage 62 becomes high-pressure in this way, the high-pressure oil flows through the orifice 40 formed in the poppet 18.
It flows into the spring chamber 22 of the relief valve 2 via the spring chamber 22 and at the same time acts on the adjusting piston 28 through the small hole 35. Also in this case, as in the case of starting, the set pressure of the relief valve 2 is low at the start of braking and becomes high thereafter, so that the shock at the start of braking can be alleviated.

Also, when the switching valve 4 is set to the right position, the relief valve 2,
It is natural that 3 is activated.

In the first embodiment, the orifices 33 and 34 are provided in the spaces 31 and 32, and the adjustment piston 2
8 and 29, but the space part 3
A spring may be interposed within 1, 32 to control the movement of the adjusting piston.

The second embodiment shown in FIG. 4 differs from the first embodiment only in its relief valve, and the rest is completely the same as the first embodiment.

Therefore, only one relief valve 41 will be specifically explained, and details of the other components will be omitted.

The relief valve 41 in this second embodiment has its pressure connection port 42 communicating with the branch passage 12. The pressure connection port 42 serves as a seat for the poppet 43, and a holding member 44 for slidably holding the poppet 43 is attached to the outer periphery that substantially corresponds to the seat portion.

A relief housing 45 forming a spring chamber 57 of the relief valve 41 is attached to the holding member 44. A spring is interposed in the relief housing 45 to press the poppet against the seat of the pressure connection port 42.

In addition, the pressure receiving area S ₁ of the poppet facing the seat part
In contrast, the pressure receiving area _S2 of the spring chamber 57 is made smaller.

Further, a space 46 is formed between the relief housing 45 and the holding member 44. Also, this relief housing 45
The outer side of the poppet 43 is a large diameter portion 47, and an adjustment piston 48 is engaged with the inner periphery of this large diameter portion 47.

The adjustment piston 48 has a sliding portion 49 that is in slidable contact with the large diameter portion 47, a cylindrical portion 50 that has a smaller diameter than the sliding portion 49 and is in a relationship that allows it to protrude into the space 46, and The protruding portion 51 has a smaller diameter than the portion 49 and is formed outward from the protruding portion 51 .

The sliding portion 49 and the relief housing 4
The stepped portions 52 of No. 5 together form a space 53, and this space 53 communicates with the main passage 62 via an orifice 54 and a passage 55.

Furthermore, the protrusion 51 and the relief housing 4
The adjustment chamber 66 is formed by the adjustment piston 48 and the large diameter portion 47 of the adjustment piston 48.
It communicates with a spring chamber 57 through a notch 56 formed at the outer end of the spring chamber 57, so that the pressure oil in the spring chamber 57 acts on the surface of the piston 48 in the adjustment chamber 66.

In the figure, reference numeral 58 is an orifice formed in the poppet 43, 59 is a spring, and 60 is an adjustment screw for adjusting the spring load of the spring.

Thus, when the actuator is activated or braking is started, the pressure oil that has flowed from the orifice 58 into the spring chamber 57 passes through the notch 56, flows into the adjustment chamber 66, and acts on the adjustment piston 48.

When the pressure oil acts on the adjusting piston 48 in this way, the piston 48 moves to the right in FIG. 4 while pushing out the oil in the space 53 from the orifice 54. When the adjustment piston 48 moves, the volume of the adjustment chamber 66 is expanded accordingly. Since the volume of the spring chamber 57 is substantially expanded by the expanded volume, the pressure inside the spring chamber 57 is maintained at a low pressure.

While the adjusting piston 48 is moving, the hydraulic oil in the spring chamber 57 flows into the adjusting chamber 66, so that a pressure difference is generated before and after the orifice 58 formed in the poppet 43. Since the effect of this differential pressure and the difference between the pressure receiving areas S ₁ and S ₂ act synergistically, the relief valve 41 opens at a low pressure.

Therefore, the set pressure of the relief valve 41 is determined by the spring load of the spring 59, and the relief valve functions as a low-pressure relief valve to relieve the shock when starting the actuator or starting braking.

Also, when the adjustment piston 48 has completely moved,
The pressure on the pressure connection port 42 side and the pressure on the spring chamber 57 side become equal.

Therefore, the set pressure is determined by the spring load of the spring 59 and the difference between the pressure receiving areas S ₁ and S ₂ .
The relief valve 41 functions as a high pressure relief valve.

Therefore, this second embodiment is functionally identical to the first embodiment.

[Brief explanation of the drawing]

Figures 1 to 3 show the first embodiment of this invention, with Figure 1 being a sectional view and Figure 2 being a cross-sectional view.
3 is a circuit diagram, and FIG. 4 is a sectional view of main parts of the second embodiment. a...Casing, 2,3,4...Relief valve, 16,17,42...Pressure connection port, 22,2
3,57...spring chamber, 24,25,45...
... Relief housing, 28, 29, 48 ... Adjustment piston, 31, 32, 53 ... Space, 6
3, 64, 66...Adjustment room.

Claims (1)

[Scope of utility model registration request] A counterbalance valve is connected to the upstream side of a pair of main passages formed in the casing, a motor is connected to the downstream side, and a pair of crossover type relief valves are provided, and the inflow sides of the relief valves are connected to the respective main passages. and its outflow side,
The relief valve is connected to the main passage on the opposite side to the inflow side, and an orifice is formed in this relief valve, and the pressure oil on the inflow side is introduced into the spring chamber through this orifice. In a brake valve operated by a pressure receiving area difference, an adjustment piston is provided around the spring chamber of the crossover type relief valve, and a space defined on one side of the adjustment piston is connected to an inflow of the relief valve with which the spring chamber communicates. The adjustment chamber divided on the other side is communicated with a main passage other than the main passage connected to the other side, and the adjustment piston moves toward the space, thereby adjusting the spring chamber. A brake valve configured to substantially expand its volume.