JPH0231643Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention is a counterbalance valve that applies back pressure to the actuator when the load on the actuator suddenly decreases, for example, and prevents hunting or shock during operation. The present invention relates to a damping device that prevents.

(Prior Art) The conventional device shown in FIG.
The other end faces the damping chamber 4.

When the oil discharged from the pump 6 is supplied to the supply port 5, the pressure at that time acts on the pilot chamber 3 via the orifice 7, so the spool 2
moves against the spring 8 in the damping chamber 4.

With the spool 2 moved in this way, the discharge oil that has flowed into the supply port 5 is supplied to the actuator 10 via one actuator port 9, and the return oil from this actuator 10 is transferred to the other actuator port 9. Actuator port 11 → annular recess 12 formed in spool 2 → return port 13
Return to tank 14 via .

When the spool 2 moves as described above, the hydraulic oil in the damping chamber 4 flows into the orifice 15.
Since it flows out to the return port 13 through the orifice 15, a damping effect is exerted due to the flow path resistance when passing through the orifice 15, and the damping force is calculated by the amount of leakage passing through the orifice 15. This leakage amount is between damping chamber 4 and return port 1.
The larger the differential pressure between 3 and 3, the greater the amount.

(Problems to be Solved by the Present Invention) The damping effect of the orifice is determined by the moving speed of the spool with respect to pilot pressure fluctuations, which is ultimately determined by the flow rate passing through the orifice per unit time. Therefore, if the differential pressure across the orifice is large, the flow rate per unit time will also increase, making it more difficult to obtain a damping effect.

However, in the conventional device described above, return port 1
3 communicates with the tank 14, the pressure difference between the damping chamber 4 and the return port 13 increases.
Therefore, the flow rate passing through the orifice per unit time increases, and the damping force becomes correspondingly weaker.

Therefore, in order to obtain an effective damping force with this conventional device, the opening area of the orifice 7 must be made sufficiently small, but the smaller the opening area, the more difficult the dimensional control becomes. There was a problem in that the change in damping effect due to the dimensional error became large.

It is also possible to use a clearance to exert the damping effect in place of the orifice 15, but in this case, the above-mentioned dimensional control becomes even more difficult, and there are also disadvantages in that the influence of viscosity changes due to oil temperature is large.

This invention aims to provide a damping device that reduces the pressure difference to reduce the amount of outflow from the damping chamber, and that can achieve the desired damping effect without having to strictly control the dimensions of the throttle. Make it a purpose.

(Means for Solving the Problems) In order to achieve the above object, this invention moves the spool under the action of the pilot pressure in the pilot chamber, and adjusts the return side of the actuator according to the amount of movement of the spool. In the counterbalance valve that controls the opening degree of the passage, the end of the spool opposite to the end facing the pilot chamber faces the damping chamber, and the damping chamber and the relay chamber adjacent thereto are communicated via a throttle, While guiding the pilot pressure to this relay chamber, the pressure receiving area of the spool end facing the pilot chamber is
It is designed to be larger than the pressure receiving area on the relay room side.

(Operation of the present invention) Since this invention is constructed as described above, the pressure receiving area of the spool end facing the pilot chamber is S ₂ ,
If the pressure receiving area on the relay chamber side is S ₁ , the pressure receiving area on the damping chamber side is S ₃ , the pilot pressure is P _P , and the spring force in the relay chamber is f, the thrust force F acting on the spool is F = (S ₂ − S ₁ )×P _P , and the damping pressure Pd in the damping chamber at this time becomes Pd={(S ₂ −S ₁ )×P _P −f}/S ₃ .

Therefore, by adjusting the pressure receiving areas of S ₁ , S ₂ and S ₃ , the damping pressure Pd can be reduced, the amount of outflow from the damping chamber can be reduced, and the desired damping effect can be achieved. Can be done.

(Effects of the Present Invention) Since the desired damping effect can be achieved by reducing the amount of fluid flowing out from the damping chamber, the dimensional control of the throttle does not have to be so strict.

(Embodiment of the present invention) The first embodiment shown in FIG. 1 is the same as the above-mentioned conventional device in that the structure of the main body a and the annular recess 16 are formed in the spool s.

The spool s is installed in the pilot chamber 17.
A large diameter portion 18 is formed on the side facing the
A clearance 19 is formed between this large diameter portion 18 and the spool hole of the main body a, and this clearance 19
The pilot chamber 17 is constantly communicated with the tank T via a passage 20 formed in the spool s.

In addition, a small diameter portion 21 is formed on the opposite side of the large diameter portion 18.
At the same time, the end face of this small diameter portion 21 is made to face the damping chamber 22. This damping chamber 22 includes a spring guide 2 provided in the small diameter portion 21.
3 from the relay chamber 24, the two chambers 22 and 24 communicate with each other via a clearance 25 formed between the spring guide 23 and the small diameter portion 21.

Pilot room 17 and relay room 2 as above
4 communicates with the common supply port 5 via passages 26 and 27, so that both chambers 17 and 24 have the same pressure.

In addition, the cross-sectional area of the large diameter portion 18 of the spool s is
S ₂ , the cross-sectional area of the mid-abdomen is S ₁ , the cross-sectional area of the small diameter portion 21 is
Let's say S ₃ .

Therefore, when the pump discharge oil is introduced into the supply port 5, the pressure P _P at that time is
7 and relay room 24.

At this time, the thrust F that moves the pool s to the right in the drawing becomes F = (S ₂ − S ₁ ) × P _P , and
The pressure Pd in the damping chamber 22 is Pd≈{(S ₂ −S ₁ )×P _P −f}/S ₃ .

Note that in the above equation, f is the spring force of the spring 28.

Therefore, by changing the sizes of these cross-sectional areas S ₁ , S ₂ , and S ₃ , the pressure within the damping chamber 22 can be reduced. For example, by sufficiently increasing the cross-sectional area S ₃ of the small diameter portion 21 or by decreasing S ₂ −S ₁ , the pressure in the damping chamber 22 can be lowered, and the pilot pressure P _P in the relay chamber 24 can be lowered. The pressure difference between the pressure Pd and the pressure Pd in the damping chamber 22 can be reduced.

Since the differential pressure can be reduced in this manner, the flow rate passing through the clearance 25 can be reduced, and even if the clearance 25 is increased, a sufficient damping effect can be exerted.

The fact that the clearance 25 can be set large in this way means that dimension management becomes easier.

Reference numeral 29 in the figure is a check valve, which opens when the volume of the damping chamber 22 expands, in other words, when the spool s returns to its original position, to supply hydraulic oil from the relay chamber 24 to the damping chamber 22. fulfills the function of supplying.

The second embodiment shown in FIG.
A piston 30 is provided on the end side of the spool s opposite to the piston 30.
A damping chamber 32 with a spring 31 interposed therein is formed behind the damping chamber 32 .

The relay chamber 33 and the damping chamber 32, which are formed by sandwiching the piston 30, are connected to the piston 3.
0 and communicate with each other via a clearance 34 formed around the first
This is similar to the example.

The reference numeral 35 in the figure is a check valve formed on the piston 30, which opens when the piston 30 returns to its original position to suck hydraulic oil into the damping chamber 32.

In the case of this second embodiment as well, if the pressure receiving area on the damping chamber 32 side is set to _S3 , the same effects as in the first embodiment can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a first embodiment of this invention, FIG. 2 is a sectional view showing a second embodiment, and FIG. 3 is a sectional view of a conventional device. 10... Actuator, s... Spool, 1
7... Pilot chamber, 22, 32... Damping chamber, 24, 33... Relay room, 25, 34... Clearance constituting the throttle.

Claims (1)

[Scope of utility model registration request] In a counterbalance valve that moves the spool under the action of the pilot pressure in the pilot chamber and controls the opening of the return passage of the actuator according to the amount of movement of the spool, the end opposite to the spool end facing the pilot chamber facing the damping chamber, communicating the damping chamber and the adjacent relay chamber via a throttle, and guiding the pilot pressure to the relay chamber, while the pressure-receiving area of the spool end facing the pilot chamber is A counterbalance valve damping device designed to be larger than the pressure receiving area on the relay room side.