JP2899525B2 - Vibration prevention device at the time of stop of actuator with inertial load - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration at the time of stop which reduces vibration generated when an actuator of a construction machine having a large inertial load such as a boom cylinder of a hydraulic shovel is operated and suddenly stops as soon as possible. It relates to a prevention device.

[0002]

2. Description of the Related Art When a front working machine of a hydraulic shovel, particularly a boom cylinder raising / lowering operation is stopped, an operation valve is rapidly returned to a neutral position so as to stop the movement of the cylinder rapidly.
The inertia of the front structure, the inside of the cylinder and the operation valve
Due to the compressibility of the hydraulic oil stored in the pipeline between the cylinders, large vibrations (swings) continue to impair the operator's operational feeling. When the continuous operation after the stop is performed, accurate positioning of the hydraulic actuator in the front work machine at the time of the stop is necessary in order to be able to immediately shift to the work, and this continuous vibration is harmful. In addition, a nervous operator returns the operation valve to neutral by slow operation to stop the hydraulic actuator slowly. However, a slight vibration may still remain, and the operator tends to dislike this.

Conventionally, as a device for reducing this kind of vibration at the time of stoppage, there has been proposed a vibration prevention device at the time of stoppage of a hydraulic actuator having an inertial load as shown in Japanese Utility Model Laid-Open No. 6-14504. This conventional vibration preventing device will be described with reference to FIG.

In FIG. 4, a pump 11 and a tank 12 are connected to an oil supply port and an oil discharge port of a directional control valve 13, and two output ports of the directional control valve 13 are connected to hydraulic actuators (power shovels) via lines 14 and 15. Boom cylinder etc.)
The hydraulic actuator 16 supports an inertial load 17 such as a boom, which is connected to the head side chamber 16a and the rod side chamber 16b. Of the three positions of the directional control valve 13 shown in FIG. 1, the upper side of the neutral position 13a is the actuator contraction operation position 13b, and the lower side is the actuator extension operation position 13c.
It is.

A branch pipe 14 a branched from a pipe 14 connecting one output port of the direction switching valve 13 and the head side chamber 16 a of the hydraulic actuator 16 is provided at one end of a device main body 22 of the damping device 21. Communicated with part 23,
A branch pipe 15a branched from a pipe line 15 connecting the other output port of the direction switching valve 13 and the rod side chamber 16b of the hydraulic actuator 16 is provided at a port provided at the other end of the device body 22 of the damping device 21. It is communicated with the unit 24.

[0006] Restrictors (hereinafter referred to as orifices) 25 and 26 for consuming vibration energy by heat generation are provided in the port portions 23 and 24 to which the branch pipes 14a and 15a are connected.

In the damping device 21, a small-diameter cylinder 31 and a large-diameter cylinder 32 are continuously formed in the device body 22 between the pair of orifices 25 and 26, and a low inertia piston 33 is provided in each of the cylinders 31 and 32. A small-diameter piston portion 33a and a large-diameter piston portion 33b formed at both ends are slidably fitted in a liquid-tight manner with a seal.

The small-diameter piston portion 33a faces a head-side damping chamber 35 formed in the small-diameter cylinder 31, and the large-diameter piston portion 33b is a large-diameter rod formed in the large-diameter cylinder 32. Facing the side damping chamber 36. The head side damping chamber 35 is connected to the head side branch pipe 14a through the orifice 25, and the rod side damping chamber 36
Is connected to the rod side branch pipe 15a via an orifice 26. An intermediate chamber 37 between the small-diameter piston section 33a and the large-diameter piston section 33b is provided with an oil drain pipe drawn from a drain port 38.
39 communicates with the tank 12.

The principle of the vibration preventing device shown in FIG. 4 is that if the directional control valve 13 is suddenly returned to the neutral position 13a in order to stop the hydraulic actuator 16, the directional control valve 13 Oil to the side is shut off.

The time average pressure (P16a) of the head side chamber pressure P16a of the hydraulic actuator 16 generated by the inertial load 17
) And rod side chamber pressure P1 generated by vibration rebound
6b time average pressure (P16b) and damping device 2
When the relationship of (P16a) × A35 = (P16b) × A36 is established between the piston cross-sectional areas A35 and A36 at both ends of 1, the low inertia piston 33 is used as an equilibrium point and the balance position is Vibration displacement according to the hydraulic vibration is performed centering on the middle position (not both ends of the damping device).

Due to the vibration displacement of the low inertia piston 33, a flow of oil passing through the throttles 25 and 26 is generated, and as a result, as shown in FIG.
Second) The continuous pressure oscillation attenuates in a short time (2.1 seconds in the data) as shown in FIG. That is, the compression energy of the oil in the hydraulic actuator 16 and the pipe due to the shutoff of the direction switching valve 13 and the vibration energy in the closed circuit constituted by the inertial load 17 are dissipated in a short time.

[0012]

However, the time average pressure (P16a) is too large because the inertia load 17 is too large, and the time average pressure (P16a) is too small because the inertia load 17 is too small. When the relational expression (1) with the time average pressure (P16b) is no longer established, the position of the low inertia piston 33 is fixed to the upper end of the cylinder 31 or the lower end of the cylinder 32 in FIG. And the dissipation of vibration energy as described above cannot be achieved. Therefore, the conventional one has a problem that the effective range of the load 17 is limited.

The present invention has been made in view of the above points, and reduces residual vibration of a hydraulic actuator having an inertial load when the actuator is stopped, thereby reducing operator fatigue.
It is another object of the present invention to provide a vibration prevention device at a stop which improves operability and which can effectively work on a wide-band load.

[0014]

According to a first aspect of the present invention, there is provided a fluid pressure circuit in which fluid pressure generated by a fluid pressure source is controlled to be supplied to and discharged from a fluid pressure actuator by a direction switching valve. A throttle is connected between a pipe line connecting one output port and one chamber of the hydraulic actuator and a pipe line connecting the other output port of the directional control valve and the other chamber of the hydraulic actuator. A plurality of damping devices are connected in parallel, and in these damping devices, low-inertia pistons having different pressure receiving area ratios at both ends are slidably fitted into different-diameter cylinders, and are provided at both ends of each different-diameter cylinder. A stop vibration prevention device for an actuator having an inertial load having a damping chamber communicated with the throttle.

According to a second aspect of the present invention, there is provided a fluid pressure circuit in which fluid pressure generated by a fluid pressure source is controlled to be supplied to and discharged from a fluid pressure actuator by a direction switching valve. A damping device is connected via a throttle between a pipe connecting one chamber of the pressure actuator and a pipe connecting the other output port of the directional control valve and the other chamber of the hydraulic actuator. In this damping device, a combination of a plurality of stepped cylindrical low inertia pistons having different pressure receiving area ratios at both ends in a nested and slidably fitted manner is slidably fitted in a cylinder having a different diameter. This is a vibration prevention device for a stop of an actuator having an inertial load having a configuration in which damping chambers communicating with the throttles are provided in both end portions of different diameter cylinders.

According to a third aspect of the present invention, there is provided a fluid pressure circuit in which fluid pressure generated by a fluid pressure source is controlled to be supplied to and discharged from a fluid pressure actuator by a direction switching valve. A damping device is connected via a throttle between a pipe connecting one chamber of the pressure actuator and a pipe connecting the other output port of the directional control valve and the other chamber of the hydraulic actuator. In this damping device, a low inertia piston is slidably fitted on the inner surface of a cylinder barrel having a shape that gradually expands from the center toward both ends, and the low inertia piston slides on the inner surface of the cylinder barrel. A bladder made of a highly elastic material which is movable and can follow the change in the cylinder inner diameter and which can be freely expanded and contracted is attached to both ends, and a fluid pressure actuator is provided in the inner space of these bladders. Fill material at high pressure is enclosed than the maximum pressure generated within a stop device for preventing vibration actuator having an inertial load configurations damping chamber that is passed through the diaphragm and with the interior of the opposite ends of the cylinder barrel are provided.

[0017]

According to the first aspect of the invention, the vibration pressure generated by the fluid pressure actuator is guided to the damping chamber of the damping device via the throttle, and the low inertia piston is slid to generate vibration energy by the throttle. And the vibration generated when the fluid pressure actuator is stopped is attenuated at an early stage. At this time, by sliding a plurality of low inertia pistons having different pressure receiving area ratios, the ratio of the time average pressure between one chamber and the other chamber of the fluid pressure actuator generated when the inertial load is stopped is reduced to the conventional value. Whereas the balance condition is one point, the present configuration has a plurality of points, so that the oscillating vibration pressure of the fluid pressure actuator can be attenuated early in a wide band. Therefore, even if the time average pressure fluctuates due to the lightness of the load, the gentle operation of the operator, and the like, the effect is wider in comparison with the conventional case.

According to a second aspect of the present invention, each stepped cylindrical low inertia piston absorbs vibration at each tuning point, and, for example, one piston is pushed to the end face and the other pistons are united. In some cases, all the pistons move together and move at the same time. Therefore, even if the number of pistons is the same, the pressure receiving area ratio is larger than that of the first aspect of the invention, so that tuning can be performed in a wider band.

According to the third aspect of the present invention, the pressure receiving area of the bladder at both ends continuously and smoothly changes according to the axial movement of the low inertia piston. Changes continuously due to the axial movement of
Broadband tuning can be achieved more effectively.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to a first embodiment shown in FIG.
This will be described in detail with reference to the second embodiment shown in FIG. 2 and the third embodiment shown in FIG.

First, FIG. 1 shows a basic hydraulic circuit used in a working machine system and the like of a power shovel according to a first embodiment of the present invention. The two output ports of the directional control valve 13 are connected to the oil port, and the two output ports of the directional control valve 13 are connected to the head side chamber 16a and the rod side chamber of a hydraulic actuator (such as a hydraulic cylinder for operating a boom of a hydraulic shovel, hereinafter referred to as a hydraulic actuator) 16 via lines 14 and 15. The inertial load 17 such as a boom is supported by the hydraulic actuator 16. The upper side of the neutral position 13a of the three positions of the direction switching valve 13 shown in FIG. 1 is the actuator contraction operation position 13b, and the lower side thereof is the actuator extension operation position 13c.

A branch pipe 14a branched from a pipe 14 connecting one output port of the direction switching valve 13 and the head side chamber 16a of the actuator 16 is provided with three damping devices 21-1 and 21-1.
21-2, 21-3 are connected to respective port sections 23-1, 23-2, 23-3 provided at one end of each device body 22-1, 22-2, 22-3, and have directions. A branch pipe 15a branched from a pipe line 15 connecting the other output port of the switching valve 13 and the rod side chamber 16b of the actuator 16 is provided with three damping devices 21-1,
The ports are connected to respective port sections 24-1, 24-2, and 24-3 provided at the other ends of the device bodies 22-1, 22-2, and 22-3 of 21-2 and 21-3.

The vibration energy is consumed in the ports 23-1, 23-2, 23-3 and 24-1, 24-2, 24-3 connected to the branch pipes 14a, 15a by heat generation. Apertures (hereinafter referred to as orifices) 25-1, 25-2, 25-3 and 26-1, 26-2, 26
-3 are provided respectively. Each orifice 25-1,
25-2, 25-3 and 26-1, 26-2, 26-3 are the branch pipes 14a, 15a
May be provided in-line in the middle of the piping.

Each of the damping devices 21-1, 21-2, 21
-3 is located between one orifice 25-1, 25-2, 25-3 and the other orifice 26-1, 26-2, 26-3. , 22-3, small-diameter cylinders 31-1, 31-2, 31
-3 and large diameter cylinders 32-1, 32-2, 32-3 are continuously formed,
The low inertia pistons 33-1, 33-2, 33
Small diameter piston parts 33a1, 33a2, 33 formed at both ends of -3
a3 and large-diameter piston parts 33b1, 33b2, 33b3 are slidable,
They are fitted in a liquid-tight manner by a seal (not shown).

The small-diameter piston portions 33a1, 33a2, 33a3
The large-diameter piston portions 33b1, 33b2, 33b3 face the head-side damping chambers 35-1, 35-2, 35-3 formed in the small-diameter cylinders 31-1, 31-2, 31-3. Is the large-diameter cylinder 32
-1, 32-2, and 32-3, facing large-diameter rod-side damping chambers 36-1, 36-2, and 36-3.

As described above, the three damping devices 21
-1, 21-2, 21-3 are connected in parallel and their low inertia piston
The pressure receiving area ratio of the large-diameter piston parts 33b1, 33b2, 33b3 of 33-1, 33-2, 33-3 and the small-diameter piston parts 33a1, 33a2, 33a3 (AR1 /
(AP1), (AR2 / AP2), and (AR3 / AP3) are set to different values.

That is, the ratio of the cross-sectional area of the large-diameter piston portion 33b1 to the cross-sectional area of the small-diameter piston portion 33a1 in the low inertia piston 33-1 is AR1 / AP1, and the low-inertia piston 33-2 has a large diameter. The ratio of the cross-sectional area of the piston portion 33b2 to the cross-sectional area of the small-diameter piston portion 33a2 is AR2 / AP2, and the cross-sectional area of the large-diameter piston portion 33b3 and the cross-sectional area of the small-diameter piston portion 33a3 in the low inertia piston 33-3. Are AR3 / AP3, and their respective ratios AR1 / AP1, AR2 / AP2, and AR3 / AP3 have different numerical values.

The head side damping chambers 35-1, 35-2, 35-3 are connected to the head side branch pipe 14 through orifices 25-1, 25-2, 25-3.
a, and the rod side damping chambers 36-1, 36-2, 36-3
Is the orifice 26-1,26-2,26-3 through the rod side branch
Connected to 15a.

The intermediate chambers 37-1, 37-2, 37-2 between the small-diameter piston portions 33a1, 33a2, 33a3 and the large-diameter piston portions 33b1, 33b2, 33b3.
37-3 is communicated by drain passages 38-1 and 38-2, and further communicated with the tank 12 by an oil drain pipe 39 drawn from the drain passage 38-3.

The damping chambers 35-1, 35-2, 35-3 and 36
-1, 36-2, 36-3 are made smaller and larger diameters because of the inertial load 17
Since the head side chamber 16a of the hydraulic actuator 16 is higher in time average than the rod side chamber 16b due to an eccentric load (gravity) F acting on the low inertia piston 33,
-1, 33-2, and 33-3 become the damping chambers 36-1, 36-2, and 36 over time.
This is to prevent bias toward the -3 side.

That is, the relatively high pressure head side chamber 16a
The pressure-receiving area of the small-diameter piston portions 33a1, 33a2, 33a3 facing the damping chambers 35-1, 35-2, 35-3 connected to the damping chambers 36-1, 35-2, 35-3 connected to the relatively low-pressure rod side chamber 16b.
Large diameter piston parts 33b1, 33b2, 33 facing -1, 36-2, 36-3
By making the pressure receiving area smaller than the pressure receiving area of b3, the forces applied to both end faces of the low inertia pistons 33-1, 33-2, and 33-3 are balanced over time, and the low inertia pistons 33-1, 33-2, and 33 are maintained. -3, damping chambers 35-1, 35-2, 35-3 at both ends
36-1, 36-2, and 36-3 are maintained.

As described above, the first embodiment shown in FIG. 1 is not one conventional low inertia piston but a pressure receiving area ratio (AR1 / A).
P1 etc.) multiple low inertia pistons 33-1, 33-2, 33
-3 are connected in parallel with damping devices 21-1, 21-2, and 21-3. Although three types of damping devices 21-1, 21-2, and 21-3 are provided in FIG. 1, a larger number of damping devices having different pressure receiving area ratios may be installed in parallel, or two types of damping devices may be provided. Damping devices may be installed in parallel.

Next, the operation of the embodiment shown in FIG. 1 will be described.

In FIG. 1, the directional control valve 13 is moved from the neutral position 13a to the actuator contraction operation position 13b or the extension operation position 13c.
If the damping devices 21-1, 21-2, and 21-3 are not provided when the operation is returned to the neutral position 13a suddenly after the operation shown in FIG.
The pressure oscillation is repeated as in the actual measurement data shown in FIG. Since there are damping devices 21-1, 21-2, and 21-3, pipeline 14,
Vibration pressure due to compressibility in 15 is low inertia piston 33-1, 33-
Acts on both end faces of 2,33-3.

Therefore, when the vibration pressure is reversed between the head side and the rod side, the low inertia pistons 33-1, 33-2, and 33-3 slide in reverse at the same cycle as the vibration cycle from their respective balance points. During this time, the oil flow accompanying the compressibility in the pipelines 14 and 15
Vibration energy is consumed and lost due to heat generation through the throttle resistance of each of the orifices 25-1, 25-2, 25-3 and the other orifices 26-1, 26-2, 26-3.

On the other hand, since the load 17 of the hydraulic actuator 16 has a large inertia, it hardly moves.
As shown in FIG. 5B, the vibrations -1, 33-2, and 33-3 almost completely absorb the compressible oil for generating vibrations, and the vibrations are rapidly attenuated and stopped.

At this time, the ratio of the time average pressure (P16a) of the head side chamber 16a of the hydraulic actuator 16 and the time average pressure (P16b) of the rod side chamber 16b generated by the rebound when the inertial load 17 stops is shown in FIG. In the prior art shown in (1), it was possible to balance at one point shown in equation (1), but in this configuration, it was possible to balance at three points, and the hydraulic actuator was widened accordingly.
16 rocking vibration pressures can be attenuated early.

That is, (P16a)
The relational expression of AP1 = (P16b) .AR1 is obtained from the device 21-2.
The relational expression of (P16a) .AP2 = (P16b) .AR2 is obtained by the equation, and (P16a) .AP3 = (P16a) by the device 21-3.
b) Since the relational expression of AR3 can be satisfied, vibration is absorbed by the damping devices 21-1, 21-2, 21-3 tuned from among these three balance points.

That is, from each of the above relational expressions, (P
16a) · AP1 / (P16b) · AR1 and (P16a) · AP2
/ (P16b) · AR2 and (P16a) · AP3 / (P16b)
Automatically tune the one with the calculated value closest to 1 from among AR3, and absorb the vibration by the low inertia pistons 33-1, 33-2, 33-3 corresponding to the tuning point.

As described above, since the tuning range of FIG. 1 can be widened, even if the time-average pressures (P16a) and (P16b) vary due to the lightness of the load or the gentle operation of the operator, the tuning range is wider than before. There is an effect that the vibration absorbing function can be maintained.

Next, FIG. 2 shows a second embodiment of the present invention. Since the basic circuit of FIG. 2 is the same as that of the conventional example of FIG. 4, the same portions are denoted by the same reference numerals and description thereof will be omitted.

A branch pipe 14a branched from a pipe 14 connecting one output port of the direction switching valve 13 and the head side chamber 16a of the actuator 16 is provided at one end of the device main body 22 of the damping devices 21-456. Communicated with port 23,
Further, a branch pipe 15a branched from a pipe 15 connecting the other output port of the direction switching valve 13 and the rod side chamber 16b of the actuator 16 is provided at the other end of the device main body 22 of the damping device 21-456. It is communicated with the port unit 24.

And, orifices 25 and 26 are provided in the ports 23 and 24 to which the branch pipes 14a and 15a are connected so that the vibration energy is consumed by heat generation. The orifices 25, 26 may be provided in-line in the pipes of the branch pipes 14a, 15a.

In the damping device 21-456, a small-diameter cylinder 31 and a large-diameter cylinder 32 are continuously formed in the device body 22 between the pair of orifices 25 and 26, and a plurality of steps are provided in the different-diameter cylinder. Cylindrical low inertia piston 33
-4, 33-5, and 33-6 are slidably assembled in a nested manner and are slidably fitted in a liquid-tight manner.
-4, 33-5, 33-6 are small-diameter piston portions 33a4, 33a5, 33a6 and large-diameter piston portions 33b4, 33 formed at both ends thereof.
b5 and 33b6 are slidably fitted to each other in a liquid-tight manner.

In the innermost low inertia piston 33-4, the ratio of the cross-sectional area of the large-diameter piston portion 33b4 to the cross-sectional area of the small-diameter piston portion 33a4 is AR4 / AP4, and the ratio of the intermediate low-inertia piston 33-5 is The ratio of the cross-sectional area of the large-diameter piston portion 33b5 to the cross-sectional area of the small-diameter piston portion 33a5 is AR5 / AP5, and the cross-sectional area of the large-diameter piston portion 33b6 and the small-diameter piston at the outermost low inertia piston 33-6. The ratio of the section 33a6 to the cross-sectional area is AR6 / AP6, and their respective ratios AR4 / AP4, AR5 / AP5, AR6
/ AP6 are different values.

The small diameter piston sections 33a4, 33a5, 33a6 are
It faces the head-side damping chamber 35 formed in the small-diameter cylinder 31 and has the large-diameter piston portions 33b4, 33b.
b5 and 33b6 face the large-diameter rod-side damping chamber 36 formed in the large-diameter cylinder 32.

The head side damping chamber 35 has an orifice 25
The rod-side damping chamber 36 is connected to the head-side branch pipe 14a through an orifice 26.
Connected to a.

Intermediate chambers 37-4, 37-5, 37-6 are formed between the low inertia pistons 33-4, 33-5, 33-6 and the device body 22, and these intermediate chambers 37-4 are formed. , 37-5, 37-6 are connected to the low inertia pistons 33-5, 33-6, the drain passages 38-4, 38-5, 38-6 provided in the device body 22, and the oil drain pipe 39, respectively. 12
Is communicated to.

The reason why the diameters of the damping chambers 35 and 36 are made small and large is that the head side chamber 16a of the actuator 16 is more time-averaged than the rod side chamber 16b because the eccentric load (gravity) F acts on the inertial load 17. Then, since the pressure is high, the low inertia pistons 33-4, 33-5 and 33-6 are placed in the damping chamber 36.
This is to prevent bias toward the side.

That is, the relatively high pressure head side chamber 16a
Small diameter piston part 33 facing the damping chamber 35 connected to
The pressure receiving area of a4, 33a5, and 33a6 is increased by the large-diameter piston portion 33b facing the damping chamber 36 connected to the low-pressure rod-side chamber 16b.
By making it smaller than the pressure receiving area of 4, 33b5, 33b6,
When the forces applied to both end faces of the low inertia pistons 33-4, 33-5, and 33-6 are averaged over time, the balance is maintained.
Damping chambers 35 and 36 are secured at both ends of 33-5 and 33-6.

In the second embodiment shown in FIG. 2, three low step inertia pistons 33-4, 33-5 and 33-6 are combined in a nested manner. The number of the low inertia pistons may be further increased, or a combination of two types of stepped cylindrical low inertia pistons in a nested form may be used.

Next, the operation of the embodiment shown in FIG. 2 will be described. As in the first embodiment shown in FIG. 1, each of the low inertia pistons 33-4, 33-5 and 33-6 is set at each tuning point. In addition to absorbing the vibration, for example, one piston 33-4 is pushed to the end face and the other piston 33-5,
33-6 united shape or all pistons 33-4,33
-5 and 33-6 move together and move at the same time, etc., so that the pressure receiving area ratio changes in each case. Therefore, a larger pressure receiving area ratio than in the first embodiment of FIG. It has substantially and can be tuned in a wider band.

Note that 33c4, 33c5, 33c6, 33d4, 33d5, 33
d6 is the orifice 25, when each piston contacts the end face.
This is a slit (groove) for allowing the pressure oil from 26 to smoothly act on the end face of another piston.

Next, FIG. 3 shows a third embodiment of the present invention. Since the basic circuit of FIG. 3 is the same as that of the conventional example of FIG. 4, the same portions are denoted by the same reference numerals and description thereof will be omitted.

A branch pipe 14a branched from a pipe 14 connecting one output port of the direction switching valve 13 and the head side chamber 16a of the actuator 16 is provided at one end of a device body 22 of the damping device 21-7. The port 23 communicates with the other output port of the directional control valve 13 and the actuator.
A branch pipe 15a branched from a pipe line 15 connecting the rod side chamber 16b to a device body 22 of a damping device 21-7.
Is connected to a port section 24 provided at the other end of the port.

The orifices 25 and 26 are provided in the ports 23 and 24 to which the branch pipes 14a and 15a are connected so as to consume vibration energy by heat generation. The orifices 25, 26 may be provided in-line in the pipes of the branch pipes 14a, 15a.

The damping device 21-7 has a pair of trapezoidal cylinder barrels 31a7, 31b7 symmetrically formed in the device body 22 between the pair of orifices 25, 26 and as a whole from the center to both ends. The upper piston portion 33a7 in the figure is formed continuously on the inner surface of the curved shape (the inner surface of the spool) that gradually expands, and attached to both ends of the low inertia piston 33-7 on the inner surface of the spool of the cylinder barrels 31a7 and 31b7. The lower piston part 33b7 in the figure is slidably fitted in a liquid-tight manner.

The piston portions 33a7, 33b7 are mounted between a pair of regulating plates 33a71, 33b71, respectively, and are made of a high elastic material (slidable on the inner surface and the outer surface of the spool and capable of following a change in the cylinder inner diameter). And bladders 33a72 and 33b72 formed to be freely expandable and contractible by rubber or resin), and a pressure higher than the maximum pressure generated in the hydraulic actuator 16 in the innermost space of these bladders 33a72 and 33b72 in their most contracted state. High-pressure filling material 33a73, 33b7 enclosed by pressure
3

The upper bladder 33a72 is connected to the cylinder barrel 31.
a7 facing the head side damping chamber 35, and the lower bladder 33b72 has a cylinder barrel 31b7.
It faces the rod side damping chamber 36 formed therein.

Next, the operation of the third embodiment shown in FIG. 3 will be described. Since the eccentric load (gravity) F acts on the inertial load 17, the head-side chamber 16a of the actuator 16 is connected to the rod-side chamber.
Since the pressure is high when the time average is higher than 16b, the low inertia piston 33-7 is displaced from the head side damping chamber 35 toward the rod side damping chamber 36 as shown in FIG.
At this position, the forces acting on the piston portions 33a7, 33b7 at both ends maintain balance when the time is averaged, and one piston portion 33a7 has a relatively small diameter and the other piston portion 33b7 has a relatively large diameter, maintaining a balance point. .

The low inertia piston 33-7 slides in reverse in the axial direction at the same period as the vibration period from the balance point as in the first embodiment of FIG. It is consumed by heat and absorbs and attenuates vibration.

At this time, as the low inertia piston 33-7 moves in the axial direction, the pressure receiving areas APv and ARv at both ends continuously and smoothly change. Therefore, the pressure receiving area ratio (ARv / APv) also changes continuously.

That is, the third embodiment of FIG. 3 is a more flexible version of the first embodiment of FIG. 1 and the second embodiment of FIG. 2, and as described above, the pressure receiving area of the low inertia piston 33-7. Since the ratio (ARv / APv) changes continuously, the slidable high pressure bladders 33a72 and 33b72 and the high pressure filling materials 33a73 and 33b73 are used.
If the follow-up performance is good, the thread-wound cylinder barrels 31a7, 31b7
By setting the change ratio of the cross section of to a sufficiently large value, wideband tuning can be performed more effectively.

As described above, according to each of the first, second and third embodiments, the vibration preventing device, which is a conventional one-point tuning, is made wider by a mechanism having a variation in the pressure receiving area ratio. A multipoint tuning type vibration prevention device capable of attenuating rocking vibration pressure of a hydraulic actuator generated under a load range and various operation conditions at an early stage can be provided.

[0065]

According to the first aspect of the present invention, a plurality of damping devices are connected in parallel between the conduits via a throttle, and these damping devices have low inertia having different pressure receiving area ratios at both ends. The piston is slidably fitted in the cylinders of different diameters, and the damping chambers communicating with the throttles are provided in both ends of each cylinder of different diameters. By giving variations to the pressure receiving area ratio, even if the time average pressure fluctuates due to lightness of load, gentle operation of the operator, etc., it can be improved to a vibration prevention device that is more effective than before, and a wider load range, various The swing vibration pressure of the fluid pressure actuator generated under the operating conditions can be attenuated at an early stage.

According to the second aspect of the present invention, the case where each stepped cylindrical low inertia piston absorbs vibration at each tuning point and a plurality of low inertia pistons unite and move integrally. Therefore, even if the number of pistons is the same, the number of combinations of the pressure receiving area ratios is greater than that of the first aspect, so that the vibration can be prevented by performing tuning over a wider band.

According to the third aspect of the present invention, since the pressure receiving areas at both ends continuously and smoothly change in accordance with the axial movement of the low inertia piston, the pressure receiving area ratio also changes continuously due to the axial movement of the piston. Therefore, the optimum range for the vibration of the low inertia piston is automatically searched, so that tuning over a wider band can be more effectively secured than the inventions of the first and second aspects.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of a device for preventing vibration of an actuator having an inertial load at a stop according to the present invention.

FIG. 2 is a sectional view showing a second embodiment of the vibration prevention device.

FIG. 3 is a sectional view showing a third embodiment of the vibration prevention device.

FIG. 4 is a sectional view showing a conventional vibration preventing device.

FIG. 5 is an actually measured waveform diagram showing a change with time in a cylinder head side pressure, a rod side pressure, and the like when the boom cylinder is operated, in the case where the vibration prevention device is not provided (A) and in the case where the vibration prevention device is provided (B).

[Explanation of symbols]

 13 Directional valve 14, 15 Pipeline 16 Fluid pressure actuator 16a, 16b chamber 21 Damping device 25, 26 Throttle 33 Low inertia piston 35, 36 Damping chamber 31a7, 31b7 Cylinder barrel 33a72, 33b72 Bladder 33a73, 33b73 Filling material

Claims (3)

(57) [Claims] 1. A fluid pressure circuit in which fluid pressure generated by a fluid pressure source is controlled to be supplied to and discharged from a fluid pressure actuator by a direction switching valve, wherein one output port of the direction switching valve and one chamber of the fluid pressure actuator are connected to each other. A plurality of damping devices are connected in parallel via a restrictor between a pipeline connecting the directional control valve and a pipeline connecting the other output port of the directional switching valve and the other chamber of the fluid pressure actuator. In the damping device, low-inertia pistons having different pressure receiving area ratios at both ends are slidably fitted in cylinders having different diameters, and damping chambers communicating with the throttles are provided at both ends of the cylinders having different diameters. A vibration prevention device for an actuator having an inertial load when the actuator is stopped. 2. A fluid pressure circuit in which fluid pressure generated by a fluid pressure source is controlled to be supplied to and discharged from a fluid pressure actuator by a direction switching valve, wherein one output port of the direction switching valve and one chamber of the fluid pressure actuator are connected to each other. And a pipe connecting the other output port of the direction switching valve and the other chamber of the fluid pressure actuator, a damping device is connected through a throttle, and the damping device has two ends. A nested slidable combination of a plurality of stepped cylindrical low inertia pistons having different pressure receiving area ratios is slidably fitted in a different diameter cylinder, and is inserted into both ends of the different diameter cylinder. A damping chamber for stopping an actuator having an inertial load, wherein a damping chamber communicating with the throttle is provided. 3. A fluid pressure circuit in which fluid pressure generated by a fluid pressure source is controlled to be supplied / discharged to / from a fluid pressure actuator by a direction switching valve, wherein one output port of the direction switching valve and one chamber of the fluid pressure actuator are connected to each other. And a pipe connecting the other output port of the directional control valve and the other chamber of the fluid pressure actuator, a damping device is connected via a throttle, and the damping device is connected to the center. A low inertia piston is slidably fitted on the inner surface of a cylinder barrel having a shape that gradually expands from the part toward both ends, and the low inertia piston is slidable on the inner surface of the cylinder barrel and has a cylinder inner diameter. A bladder made of a highly elastic material capable of following changes is formed at both ends, and the maximum pressure generated in the fluid pressure actuator in the inner space of these bladders Ri fill material at high pressure is sealed, the actuator of the stop device for preventing vibration with inertial load, wherein the diaphragm and communicating the damping chamber that is passed through is provided in both ends of the cylinder barrel.