JPH0221658Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a hydraulic control valve suitable for use as, for example, a counterbalance valve, a brake valve, etc.

[Prior art]

Generally, when stopping a hydraulic actuator such as a hydraulic motor or a hydraulic cylinder in a hydraulic circuit that is subjected to inertial loads, the supply of pressure oil from the hydraulic source is cut off and the pressure oil supply/discharge port for the hydraulic actuator is quickly closed. In addition, when an external load is acting on the hydraulic actuator, from the viewpoint of preventing cavitation, a counterbalance valve is installed between the hydraulic actuator and the hydraulic It is incorporated between the source and the source.

As a counterbalance valve having the above-mentioned functions, a counterbalance valve shown in FIG. 5 is conventionally known.

A spool chamber 22 is provided in the center of the valve body 4, and oil passages 11, 11' and oil grooves 12, 1 are provided in the peripheral wall.
2' is provided, and the spool 5 is housed in the spool chamber 22 so as to be slidable in the axial direction. The spool 5 has two valve chambers, oil grooves 13 and 1.
3' and other oil holes are provided, and poppet valves 7, 7' and springs 24, 24' for pressing the valves are housed in the valve chambers, respectively. A spring receiving portion is formed at the end of the spool 5, and a centering spring 6,
6' is installed. The end faces of the spool 5 face oil chambers 10 and 10', respectively.

The discharge side of the hydraulic pump 1 and the oil tank 15 are connected to the hydraulic switching valve 2, and the hydraulic switching valve 2 and the oil passage 11,
11' is connected via hydraulic pressure lines 8, 8'. The oil grooves 12, 12' are connected to the hydraulic pressure line 9,
It is connected to the hydraulic motor 3 via 9'.

When the hydraulic switching valve 2 is in the illustrated neutral position, the spool 5 is maintained in the central position. When the hydraulic switching valve 2 is operated and switched to the specified position, the oil discharged from the hydraulic pump 1 enters the valve 2, the hydraulic pressure line 8, and the valve chamber of the poppet valve 7, and when the poppet valve 7 is opened, the oil is transferred to the hydraulic pressure line. The hydraulic motor 3 is supplied from the line 9. At the same time, pressure oil enters the oil chamber 10 through the oil passage 11, and moves the spool 5 to the right against the spring 6'. As a result, the oil groove 12' and the oil groove 13', which were previously disconnected from each other by the spool 5, are connected, and the hydraulic pressure pipes 9' and 8' are connected. In this way, the hydraulic motor 3 is rotated.

When the hydraulic switching valve 2 is switched to the position, the spool 5 is moved to the left in the opposite direction, and the hydraulic motor 3 is rotated in the opposite direction in the same manner as described above.

When the hydraulic switching valve 2 is returned to the neutral position, the pressure oil sent to the hydraulic pressure line 8 or 8' is returned to the oil tank 15, and the spool 5 is moved as shown in the figure by the reaction force of the spring 6' or 6. The rotation of the hydraulic motor 3 is stopped.

In this way, when the hydraulic motor 3 rotates,
The pressure of the pressure oil supply port is determined by the springs 6, 6' at the end of the spool 5, and is designed to prevent cavitation of the pressure oil supply port. It is necessary to stably and precisely control the opening degree on the return side, that is, the opening degree ratio between the oil grooves 12' and 13' or 12 and 13. In general, increasing the size of the oil passages 11 and 11' tends to cause the problem that the control of the opening ratio described above becomes difficult to stabilize.
4, 14' may be provided, but in this case, the speed of the pressure oil flowing into the oil chamber 10 or 10' is slow, causing a delay in the movement of the spool 5, and the discharge path is closed to the supply of pressure oil. The opening of hydraulic motor 3 is delayed.
There are disadvantages in that abnormal pressure is generated before the rotation of the pump, and cavitation occurs due to a temporary delay in blocking the discharge passage even after the supply of pressurized oil is stopped.

Therefore, by improving the above-mentioned drawbacks, it is possible to exert a large damping effect when switching the spool in the direction of actuating the actuator, and when it returns, it can quickly return to normal state by freely discharging the oil regardless of the magnitude of the damping effect. In order to make this possible, other conventional techniques configured as shown in FIGS. 6 and 7 are also known.

That is, the oil chambers 10, 1 of the valve body end plates 25, 25'
On the 0' side, spring chambers 21 and 2 are provided as damping chambers.
1' is provided, and a piston 16,
16' and pistons 16, 16' to oil chambers 10, 10'
Spring 17, 17' which presses in the lateral direction is housed. Pistons 16, 16' have oil holes 20, 2.
0′ and a hollow chamber connected to it are provided,
A spring receiving plate 23, 2 is provided with an oil hole in the hollow chamber.
3' is attached. One ends of the springs 17, 17' are received by spring receivers 23, 23'. A piston 16,
A stopper 18, 18' is attached to stop the stopper 16'. Oil holes 20, 20' and spring receiving plate 23,
Steel balls 19, 19' for opening and closing the oil holes 20, 20' are housed between the oil holes 20, 23'. That is, the steel balls 19, 19' are the valve bodies of the check valve.

When the spool 5 is in a neutral state, the piston 16,
16' is pressed by springs 17, 17' and stops 18,
18', the pistons 16,1
A constant distance D is formed between the outer end surface of 6' and the spool end surface.

The hydraulic pressure switching valve 2 is switched from the neutral position to change the pressure oil discharged from the hydraulic pump 1 to the hydraulic pressure pipe 8.
, the pressure oil pushes the poppet valve 7 and is supplied to the hydraulic motor 3 from the hydraulic pressure line 9. At the same time, pressure oil enters the oil chamber 10 through the oil passage 11, and the spool 5 is moved to the right.

When spool 5 moves to the right, piston 1
The outer end surface of 6' touches the spool end surface, and then,
The piston 16' moves against the spring 17' into the spring chamber 2.
It is pushed to the 1' side. At this time, the pressure in the spring chamber 21' increases, the steel ball 19' closes the oil hole 2', and the oil in the spring chamber 21' escapes through the gap around the outer circumference of the piston 16'. That is, the spool 5 moves to the right while exerting a large damping effect.

When the supply of pressure oil to the hydraulic pressure line 8 is cut off by operating the hydraulic pressure switching valve 2, the spool 5 moves to the spring 6'.
The reaction force returns it to the neutral state shown in FIG.
At this time, the piston 16' also rapidly returns to the stopper 18' position while self-supplying oil from the oil hole 20' due to the reaction force of the spring 17'.

When the hydraulic switching valve 2 is switched to the position, the same operation as described above is performed.

In this way, the pistons 16, 16' are slidably provided in the spring chambers 21, 21', and the pistons 16, 16' are slidably provided in the spring chambers 21, 21'.
From the oil chamber 10, 10' to the spring chamber 21, 21'
By arranging the steel balls 19 and 19' that allow pressure oil to flow only in the flow path, a large damping effect is generated when the spool 5 moves to the flow path switching side, and abnormal pressure is generated before the hydraulic motor 3 rotates. This can prevent the occurrence of cavitation in the discharge channel side flow path after the supply pressure is stopped.

However, in other conventional technologies configured as described above, the damping action is achieved through a minute gap between the outer periphery of the pistons 16, 16' and the inner periphery of the spring chambers 21, 21'. Spring chamber 21, 2
Since it utilizes the flow resistance or viscous resistance when pressure oil escapes from 1' to the oil chambers 10, 10',
There is a problem in that the damping action is greatly affected by the viscosity of the hydraulic oil. That is, the viscosity of hydraulic oil is generally inversely proportional to the oil temperature, and as the oil temperature increases, the viscosity decreases, and conversely, as the oil temperature decreases, the viscosity increases.
Even if the gap between the spring chamber 6' and the spring chambers 21, 21' is constant, the damping effect will change greatly due to fluctuations in the viscosity of the hydraulic oil.

As a result, if we expect a damping effect at high temperatures and low viscosity, the operation will be extremely slow at low temperatures and high viscosity.
Also, if you expect a damping effect at low temperature and high viscosity,
It has the disadvantage that damping effects cannot be obtained at high temperatures and low viscosity.

[Problem that the invention attempts to solve]

The present invention was developed in view of the problems of the prior art described above, and it exhibits a predetermined damping effect even when the hydraulic oil is in a high temperature and low viscosity state, and when the hydraulic oil is in a low temperature and high viscosity state, it exerts an excessive damping effect. To provide a hydraulic control valve that reduces excessive damping action by relieving the hydraulic oil in the damping chamber toward the oil chamber, thereby maintaining the responsiveness of the spool at low temperatures and high viscosity. It's about doing.

[Means for solving problems]

In order to solve the above problems, the feature of the configuration adopted by the present invention is that the damping chamber and the oil chamber are connected via an oil passage, and the opening end of the oil passage on the oil chamber side is provided with a centering spring. The opening is made at a position that should always be closed by the end face of the spring or the spring receiving member of the spring.

[Effect]

With the above configuration, the pressure in the damping chamber acts on the end face of the spring or the spring receiving member, so when the pressure oil in the damping chamber exceeds a predetermined pressure, the spring or the spring receiving member is displaced. Pressure oil in the damping chamber is relieved to the oil chamber to ensure movement of the spool.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to FIGS. 1 to 4. Components that are the same as those of the prior art shown in FIGS. 5 to 7 described above are given the same reference numerals, and their explanations will be omitted.

First, FIGS. 1 and 2 show a first embodiment of the present invention, in which 31 and 31' indicate a valve body end plate 25,
25', each oil passage 31, 3
1' one end side openings 31A, 31'A are spring chambers 21,
21', and the other end side openings 31B, 31'B are opened at positions to be closed by the end surfaces of the centering springs 6, 6'. 31'B is always closed.

Although the present embodiment is constructed as described above, its operation as a counterbalance valve is not particularly different from that of the prior art.

However, if the spool 5 moves, for example, to the right, the piston 1 will be moved by the end surface of the spool 5.
6' is pushed into the spring chamber 21', and the spring chamber 21'
As the internal pressure increases, the oil in the spring chamber 21' tries to escape into the oil chamber 10' through the gap on the outer periphery of the piston 16', but when the hydraulic oil is low temperature and highly viscous, the piston 16' and the The amount of oil leaking from the small gap between the chamber 21' and the chamber 21' is small, and the moving speed of the spool 5 is extremely slow. The flow rate flowing out from these oil grooves 12', 13' to the working hydraulic pipe 8' decreases, while the discharge flow rate from the hydraulic pump 1 is constant.
The pressure on the hydraulic pressure piping 8 side rises, and the pressure inside the spring chamber 21' also becomes extremely high.

Since the pressure oil in the spring chamber 21' acts on the spring 6' at the other end opening 31'B through the oil passage 31', the pressure inside the spring chamber 21' which has become high pressure as described above. When the spring 6' overcomes the spring force of the spring 6', the spring 6' is pressed and the other end side opening 31'B is closed to the oil chamber 1.
0'. As a result, the high-pressure oil in the spring chamber 21' is relieved from the other end side opening 31'B to the oil chamber 10' via the oil passage 31', reducing the pressure in the spring chamber 21', and moving the spool 5 toward the right side. Allow movement to. In this way, high responsiveness of the spool 5 can be ensured even at low temperatures and high viscosity.

Next, FIG. 3 shows a second embodiment of the present invention,
The feature of this embodiment is that annular grooves 41, 41' are formed on the end surfaces of the valve body end plates 25, 25' on the side of the oil chambers 10, 10' with the spring chambers 21, 21' as the center. , 41' are fitted with spacers 42, 42' which serve as spring bearing members for the springs 6, 6' so as to be movable in the axial direction. connected by oil passages 43, 43',
The other end side openings 43B, 4 of each oil passage 43, 43'
3'B is opened at a position that should always be closed by the spacers 42, 42', that is, at the deep end of the annular grooves 41, 41'. In addition,
In FIG. 3, only the members on the right side (marked with a dash "'") are shown, and the members on the left side are not shown.

This embodiment is constructed as described above, but when the spring chamber 21' becomes high pressure in the same way as the first embodiment,
Spacer 42' is displaced to the left via a plurality of oil passages 43', compressing spring 6'. As a result,
The oil passage 43' and the oil chamber 10' communicate through a gap formed between the spacer 42' and the annular groove 41', and the pressure oil in the spring chamber 21' is relieved to the oil chamber 10'. , the spool 5 can be moved to the right.

Therefore, in this embodiment, the other end side openings 43B, 43'B are not directly closed by the springs 6, 6', but are closed by the pacers 42, 42', so that the relief stabilize the function,
Further, the springs 6, 6' can be mounted in any desired orientation.

Furthermore, FIG. 4 shows a third embodiment of the present invention, in which the same components as in the second embodiment described above are given the same reference numerals.

However, in each of the above embodiments, when the spool 5 is in its neutral state, the end surface of the spool 5 and the pistons 16, 1
6', but in this embodiment, the axial dimension of the pistons 16, 16' is increased so that even when the spool 5 is in the neutral state, there is a gap D between the pistons 16, 16'. The reason is that the structure is designed to prevent this from occurring. In addition, in this embodiment, the inner peripheral side of the spacers 42, 42' and the pistons 16, 1
6' Ensure a gap δ between the outer peripheral surface and insert the spacer 4
2, 42' secures an oil passage when it moves.

Although the present embodiment is constructed as described above, its operation is the same as that of the second embodiment, so a description thereof will be omitted.

[Effect of idea]

The hydraulic control valve according to the present invention, as described in detail above, moves the centering spring or the spring bearing member of the spring when the pressure inside the damping chamber reaches a predetermined level, thereby separating the damping chamber and the oil chamber. Since the oil passage communicating between the two is configured to open toward the oil chamber, the responsiveness of the spool can be improved even when the hydraulic oil is low temperature and high viscosity. A sufficient damping effect can be expected even for low temperature and high viscosity working fluids.

[Brief explanation of the drawing]

Figures 1 and 2 show the first embodiment of the present invention; Figure 1 is a vertical sectional view of the hydraulic control valve, Figure 2 is an enlarged view of the main parts in Figure 1, and Figure 3 is the main part of the main part. FIG. 4 is an enlarged view of the main parts in the same position as FIG. 2 showing the second embodiment of the invention; FIG. 4 is an enlarged view of the main parts in the same position as FIG. 2 showing the third embodiment of the invention; FIG. 5 6 and 7 relate to other conventional technologies, FIG. 6 is a longitudinal sectional view of the hydraulic control valve, and FIG. 7 shows the main points in FIG. 6. It is an enlarged view of the part. 1...Hydraulic pump, 2...Hydraulic switching valve, 3...
Hydraulic motor, 4...Valve body, 5...Spool,
6, 6'... Spring, 7, 7'... Poppet valve, 1
0,10'...Oil chamber, 11,11'...Oil passage, 1
2, 12'... Oil groove, 13, 13'... Oil groove, 15
... Oil tank, 16, 16' ... Piston, 17,
17'... Spring, 18, 18'... Stopper, 19
...Steel ball, 20, 20'...Oil hole, 21, 21'...
...Spring chamber (damping chamber), 22...Spool chamber,
23, 23'... Spring receiving plate, 24, 24'... Spring, 25, 25'... Valve body end plate, 31, 31',
43, 43'...Oil path, 31B, 31'B, 43
B, 43'B...Opening on the other end side, 41, 41'...Annular groove, 42, 42'...Spacer.

Claims (1)

[Scope of utility model registration request] The valve body is provided with an oil passage and a spool chamber for supplying and discharging pressure oil between the hydraulic power source and the hydraulic actuator, a spool is slidably provided in the spool chamber, and both ends of the spool are connected to the valve body. An oil chamber into which the pressure oil from the hydraulic power source is guided is formed between them, and a centering spring for biasing the spool to a neutral position is provided in each oil chamber, and a centering spring is provided at both ends of the valve body. A damping chamber is formed that opens toward the oil chamber, a piston is slidably provided in each damping chamber, and a check valve is provided in each piston to allow pressure oil to flow only from the oil chamber toward the damping chamber side. In the hydraulic control valve, the damping chamber and the oil chamber are connected through an oil passage, and the opening end of the oil passage on the oil chamber side is connected to the end face of the centering spring or the spring support of the spring. A hydraulic control valve characterized in that it is configured to open at a position that should always be closed by a member.