JPS58152908A - Cushion device of cylinder - Google Patents

Abstract

PURPOSE:To obtain large cushioning action, by recirculating oil in a chamber in the high pressure side of a cylinder directly to a tank through a selector valve at operation of a cushion device. CONSTITUTION:If a piston 2 is displaced rightward to reach a position in the vicinity of a stroke end, a spool 22 is displaced rightward against urging force of a spring 25B and selected. As a result, an oil chamber C is communicated to an oil chamber D through an oil passage 21A to communicate a pipe 26 to 27. When a cushion ring 31 is fitted in a cushion chamber 29, large cushioning action can be obtained with damping action caused by flow resistance of fluid flowing in an annular gap formed between the ring 31 and the chamber 29.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cylinder cushion device that can effectively absorb an extremely large inertial force and reduce impact value and stress at the stroke end of a cylinder.

FIG. 1 shows a conventional cylinder bush blowing device.

In the figure, reference numeral 1 denotes a cylinder included in the head cover M, the opening, and the cover part IB1. A piston 2 is slidably provided in the cylinder 1, and the piston 2 creates two chambers A and H in the cylinder/1. It is defined in Piping 3.4 is connected to cylinder l, and each piping 3, 4 is connected to chamber A.
, is connected to B. The other end of the pipe 3.4 is connected to a directional switching valve 5, and by switching the directional switching valve 5, the pipes 3, 4 and the hydraulic pore 7'619 are brought into communication with the tank 7.

Next, in the middle of the pipe 3, there is provided a deceleration valve 8 consisting of a check valve 8A and a throttle 8B.・Dimitsu-operated check valve 8A allows the return oil from chamber A to flow freely, but when supplying pressure oil to chamber A, it is connected to piping 3 and is connected to piping 9t. By applying pilot pressure and canceling the reverse valve function, pressure oil can flow within the pipe 3. An electromagnetic switching valve 10 is provided in the middle of the pilot pipe 9.

The electromagnetic switching valve 1O is normally in a state where the spring IOA allows the flow of pressure oil in the die lot piping 9, and when the solenoid IOB is activated, the pressure oil in the armpit piping 9 is allowed to flow. It is configured to switch to a state where the flow of water is cut off. The solenoid IOB is connected to a limit switch 11, and the switch 11 is connected to a rod 12 that is attached to the piston 2 and protrudes from the cylinder l.
The scissor detection end 13 detects the position of the rod 12. Note that 14 in the figure indicates a relief valve.

The cylinder bush/device according to the prior art is constructed as described above, and its operation will be described below. When the directional control valve 5 is switched to the state shown in FIG. 1, the hydraulic ring 6 and the pipe 3 are connected, and the pipe 4 and the tank 7 are connected. Therefore, the pressure oil supplied from the hydraulic men f6 flows into the pipe 3 and also flows into the pilot pipe 9. Since the electromagnetic switching valve 10 is in a demagnetized state, /4 pilot pressure is supplied to the check valve 8A constituting the deceleration valve 8, and the check valve 8A opens and its check function is released. Ru. At this ninth point, pressure oil from pipe 3 is supplied to cylinder 10 chamber A,
When the piston 2 is displaced to the right in the figure and near the stroke end, the detection end 13 attached to the rod 12
As a result, the limit switch 11 is activated. The solenoid IOB of the electromagnetic switching valve 10 is energized by the signal from the limit switch 11, and the electromagnetic switching valve 10 is switched. Therefore, the supply of the master pilot pressure to the check valve 8A is cut off, so the check valve 8A is closed and the supply of pressure oil to the chamber A of the cylinder 1 is stopped.

As a result, the action of hydraulic pressure on the piston 2 is lost, so that the piston 2tli is moved only by its own inertial force, and the piston 2tli is rapidly decelerated and a cushioning action is performed.

However, the prior art cylinder cushioning device as described above has a number of drawbacks. First, since the limit switch 11 is disposed externally, the cylinder 1t--when used as an actuator for a working machine such as a construction machine, is a rock.

There is a risk of damage to the limit switch 11 due to contact with earth and sand, and also due to snow, etc.

There was also a risk that a short circuit would occur on the limit switch and the wiring connected to it.

Second, when the check valve 8A closes near the end of the stroke, a hydraulic pump occurs! Pressure oil supplied from 6 is returned to tank 7 via relief valve 14.

For this reason, the hydraulic bonder 6 must continue to operate under a load higher than the set pressure of the relief valve 14, and during this time the energy supplied to the system is wasted, resulting in a large energy loss. Third, since two valves, the electromagnetic switching valve 10 and the deceleration valve 8, are used to switch the flow path, the cushion device becomes large and requires a large installation space, and its manufacturing cost also increases. Fourthly, since the check valve is opened by armpit pressure, there is also the drawback of increased pipe resistance.

The present invention improves the above-mentioned drawbacks of the prior art, and the piston is stroke-depleted by the pressure oil supplied via piping to the negative chamber in the cylinder, which is defined into two chambers by the piston. Its feature is that it is equipped with a switching valve that is moved nearby and allows the pressure oil on the high pressure chamber side to flow back into the tank.

Below, an embodiment of the present invention will be described based on FIG. 2 and FIG. 3.

In the same figure, the same components as those in FIG.
It is generally composed of a stool 22 that is slidably provided within the stool. Oil chambers C and D are formed in the casing 21, sandwiching an oil passage 21A formed in the center thereof, and oil chambers F are provided between both end surfaces of the stool 22 and the inner wall of the casing 21, respectively. It is formed. In addition, the stool 22 has a short land 22A1 that constantly closes the space between chambers C and E.
It consists of a long land 22B1 that closes the space between the chamber and F at all times and opens and closes the oil passage 21m, and a small-diameter connecting portion 22C that connects the lands 22A and 22Bl.The stool 22 also has a mic.

Small holes 23 and 24 are drilled through holes 23 and 24 to allow D to constantly communicate with the middle chambers E and F, respectively. 25A.

25B is in each / mother Iro, To chamber E, F,
This is a spring for returning to a neutral position, which is stretched between the end surface of the sugur 22 and the inner wall of the casing 22.

Next, 26.27 is a pipe whose one end is connected to each oil chamber C and DK, and the other end is connected to cylinder l, and 28° and 29 are pipes which are connected to oil chambers C and DK.
, the respective cushion chambers 28 and 29 are attached to the piston 2 when the cushion rings 30, 31 attached to the piston 2 are inserted.

7.7 effects. Here, piping 26.2
7 to the cylinder 1, the other end 26A of the piping 26 connected to the oil chamber C is connected to the mouth of the piston 2 in the cylinder 1, assuming the axial length of the piston 2 to be t. It opens at a distance 111iL, which is slightly longer than the aforementioned length t, from the stroke end of the doper IBIIli (inner wall of the cylinder 1 in this case). On the other hand, regardless of the position of the piston 2, the oil chamber DK*9 pipe 27 is connected to the oil chamber DK* so that it communicates with the pipe 4@.
It opens in 1.

The cylinder cushion device according to the present invention has the above-described configuration, and its operation will be explained with reference to FIG. 3. When the directional switching valve 5 is operated to switch to the state shown in FIG. 2, the piston 2 is displaced to the right from the position shown by the solid line in FIG. At this time, the pipe 4 communicating with the chamber B via the Kutschiff chamber 29 is connected to the directional control valve 5.
Since it is connected to the tank 7 via the chamber B, the oil in the chamber B is returned to the tank 7. In this state, the pipe 26
．． 27 are both open to chamber B, so both pilot chambers E and F have the same pressure as chamber B. Therefore, the sgur 22 is in the neutral position as shown in FIG. 3(a).

Next, when the piston 2 is further displaced to the right and reaches the position shown by the dashed line in FIG. 2 near the stroke end, the other end 26A of the pipe 26 comes to communicate with the chamber A11411. Therefore, no! Pilot chamber E K is f26, oil chamber C
and the small hole 23t - sequentially communicate with the chamber A. Here, since the chamber A is connected to the hydraulic bonder 6 and is under high pressure, this pressure is led into the pilot chamber E, so that the pressure in the pilot chamber E becomes equal to the pressure on the return side. A differential pressure is generated between the pilot chamber F and the pilot chamber F.

Therefore, the sugur 22 is displaced to the right in the figure against the biasing force of the spring 25B, and is switched to the state shown in FIG. 3 (c4).

As a result, the oil chamber C and the oil chamber are communicated via the oil passage 21A, and the piping 26 and the piping 27 are brought into communication, so that the pressure oil in the chamber A is transferred to the piping 26, the switching valve 20, The water is then refluxed to the tank 7 via the cylinder chamber 29 and piping 4. Therefore, the action of hydraulic pressure on the piston 2 is lost, and the piston 2 is moved only by its own inertia force, causing a rapid deceleration. and,
When the cushion ring 31 and the cushion ring 31 fit into the cushion chamber 21, the cushion ring 31 and the cushion chamber 29
fLIIJ of the oil flowing through the annular gap formed between
In addition to the damping effect due to resistance, a large damping effect can be obtained.

If the directional control valve 5 is returned to the neutral position in this state, the supply and discharge of oil to cylinder/1 will be stopped, so chambers A and B will not have equal pressure. becomes equal pressure. Therefore, the spring 25B is expanded and the Sugur 22 is in the third position.
It will return to the neutral position shown in Figure (A), and the connection between the pipes 26 and 27 will be cut off.

On the other hand, when the directional control valve 5 is switched to the opposite position from that shown in FIG. Become.

Therefore, the pressure in the pilot chamber F communicating with the chamber B becomes high, and the pressure in the pilot chamber E communicating with the chamber A becomes low. As shown in the figure ←→, it is displaced to the left in the figure. However, even if the sugur 22 is displaced in this direction, the distribution f27 is not communicated with the pipe 26, so the pressure oil will not flow out from the chamber M side into the chamber A, which will interfere with the □ operation of the cylinder 1. Never.

In the above-mentioned embodiment, the cooking device according to the present invention is provided on the rod cover IB side of the cylinder 1, but a similar device can also be provided on the cylinder cover 1A side. Furthermore, the other end of the pipe 27 is not necessarily connected to the cushion 1.
Even if you open the seal bK without having to open it at 129,
Further, the switching valve 20 may be connected to the pipe 4 through the nine pipes 32 shown by dotted lines in FIG.
It is not necessarily necessary to configure it as described above as long as it is configured so that there is communication between them when the pressure becomes higher than 7. Pressure-responsive valve, CHE, which only handles the flow of pressure oil.
It may also be a valve, etc.

Furthermore, the cushion cylinders 28 and 29 are sufficient for use with the cushion device according to the present invention, and are not necessarily provided when a John action can be obtained.Furthermore, in the above embodiments, a hydraulic cylinder is described as the cylinder. However, it goes without saying that the cushion device of the present invention can also be used in pneumatic cylinders.

The cylinder cushion device according to the present invention is as described in detail above, and has the following effects.

■ When the cushion device is activated, the switching valve allows the high-pressure side chamber of the cylinder to flow directly back into the tank.
In addition to obtaining a large 7.7 effect, the hydraulic tank can be put into a no-load operating state immediately, and wasteful energy consumption within the system can be prevented.

■ Like the conventional technology (y to sui, chi to mouth).

Since the cushion device is not attached to the cushion device to detect the stroke end, each member that makes up the cushion device is made of rock.

There is no risk of contact with earth and sand, etc., and there will be no damage accidents.

(2) Since the switching valve is composed of a single valve, the structure of the entire cushion device can be downsized and manufactured at low cost.

(2) Since there is no need to provide a check valve that performs the N valve at 74°C pressure in the middle of the pipe, the pipe resistance can be reduced.

■ By configuring the switching valve to be actuated by the differential pressure between the two chambers in the cylinder, the operation of the cushion device at the end of the stroke of the piston becomes more reliable. As such, the horizontal operation of the cushion device is not affected by weather conditions such as rain or snow.

[Brief explanation of the drawing]

Fig. 1 is a system diagram showing a cylinder cushioning device according to the prior art, Fig. 2 is a system diagram showing a cylinder cushion device according to the present invention, and Figs. 3 is a vertical sectional view showing different operating positions of the switching valve in FIG. 2. 1... cylinder IJ cylinder, 2... piston, 3, 4...
Piping, 20...Switching valve, 26.27...Piping, A,
B...Room. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] a piston that is slidably provided in the cylinder and defines the cylinder into two chambers; a piping that communicates with each of the chambers and supplies and discharges pressurized oil to and from each chamber; and a switching valve that returns the pressure oil in the high pressure chamber to a tank when the piston is displaced to a position near the stroke end by the pressure oil in the high pressure chamber.