JPS61136005A - Buffer of cylinder - Google Patents

Abstract

PURPOSE:To control a piston itself to stop smoothly by providing a piston with a connecting path, and disposing a valve element adapted to open near the stroke end of the piston in the connecting path. CONSTITUTION:Connecting paths 40 connecting operating chambers 28a, 28b to each other are disposed at equal spaces in the peripheral direction in the interior of a piston 26. A rod 42 is slidably disposed in three connecting paths 40 of the connecting paths 40, respectively. Ring-shaped valve elements 44a, 44b are disposed at the opening portions of each connecting path 40, and the rod 42 is inserted and supported in the valve elements 44a, 44b. In this arrange ment, the valve elements 44a, 44b are adapted to open near the stroke end of the piston 26 so that the pressure in operating chambers 28a, 28b on both sides of the piston 26 is equalized to extinguish the drive energy of a cylinder and avoid a lowering of pressure in a cushion chamber. Thus, the piston 26 itself can be controlled to stop smoothly.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a shock absorber for a pneumatic cylinder, and more particularly, the present invention relates to a shock absorber for a pneumatic cylinder, and more particularly, the present invention relates to a shock absorber for a pneumatic cylinder. The present invention relates to a shock absorbing device for cylinders configured to communicate with each other and control the reactivation chambers to have the same pressure to decelerate the piston itself.

-M: In a pneumatic cylinder, when a piston with large kinetic energy reciprocates, unexpected accidents occur such as impacting the rod cover or hend cover at the end of its stroke and damaging it.

Therefore, in order to avoid this type of inconvenience, a cushion mechanism is generally provided at the end of the tube. A cylinder having such a conventional cushion mechanism is shown in FIG.

In this cylinder, for example, a port 6 is formed in a head cover 4 attached to the end of the tube 2, and a ring-shaped seal member 8 is fitted into the open end on the side of the tube 2. Inside the head cover 4, a hole 11Ho communicating between a cushion chamber and a port 6, which will be described later, is bored, and an orifice 12 is interposed in this passage 10. On the other hand, the tip of a piston rod 16 is fixed to the piston 14 via two cushion rings 18. In this case, the tapered surface 18a on the cushion ring 1B is approximately equal to the diameter of the seal member 8.

Therefore, near the stroke end of the piston 14 sliding in the tube 2, the cushion ring 18 comes into sliding contact with the sealing member 8, and as a result, the working chamber on the compression side is almost sealed, and the so-called A cushion chamber 19 is defined. Therefore, when the piston 14 stops at the stroke end, the air in the cushion chamber 19 is compressed near the stroke end, kinetic energy is absorbed, and the compressed air is gradually released to the outside through the passage 10. That is, it becomes possible to stop the piston 14 smoothly without colliding with the navel cover 4 at the end of its stroke.

However, in such a shock mechanism, as the pneumatic cylinder is driven at higher speeds, the exhaust flow rate from the port 6 must be increased, and as a result, the pressure on the compression side decreases, causing the inside of the cushion chamber 19 to increase. The air pressure at t must be high enough to stop the piston at its end of stroke. Therefore, when the pneumatic cylinder is driven at high speed, it is difficult for the conventional cushion mechanism to sufficiently absorb the energy during deceleration of the piston, resulting in the inconvenience that smooth stopping and buffering operation of the piston cannot be ensured.

Therefore, as a result of intensive research and ingenuity, Raikou and Meiharu installed a communication passage in the piston housed inside the tube that communicates the working chambers defined on both sides of the piston, and this communication If the passage is opened near the stroke end to equalize the pressure in both working chambers, back pressure will be applied to the compression side working chamber near the piston stroke end, and the piston speed can be reduced. The pressure drop inside the cushion chamber can also be eliminated, and as a result,
It has been found that a cylinder shock absorbing device can be obtained which increases the energy absorption capacity during deceleration of the piston and can avoid a severe collision at the end of the stroke of the piston even when the cylinder is driven at high speed, thereby eliminating the above-mentioned disadvantages.

Therefore, an object of the present invention is to reliably avoid severe collisions with the head cover and rod cover at the end of the piston stroke and to control the piston itself to stop smoothly even when the cylinder is driven at high speed or under high load. It is possible to provide a cylinder shock absorber.

In order to achieve the above object, the present invention provides a piston constituting a cylinder with a communication passage that communicates working chambers defined on both sides of the piston with each other, and the communication passage is operated under the displacement action of the piston. It is characterized by providing a valve device that opens.

Next, preferred embodiments of the cylinder shock absorbing device according to the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 2, reference numeral 20 indicates a tube, and reference numerals 22a and 22b indicate a rod cover and a head cover attached to both ends of the tube 20, respectively. The covers 222, 22b are provided with holes 24a and 24b, respectively. Four tie rods (not shown) are bridged between the force bars 22a and 22b using their respective corner portions, so that the tube 20 is fixedly tightened.

Next, a piston 26 is slidably housed inside the tube 20, and the piston 26 causes the tube 20 to
Two working chambers 23a and 28b are defined therein. A seal ring 31 is fitted into the concave groove 29 surrounding the piston 26 . A small-diameter base end 32 of the piston rod 30 passes through the center of the piston 26, and cushion rings 34a are provided on both sides of the piston 26, respectively.
34b is fitted. In fact, the cushion ring 34a,
34b is fixed with a washer 35 and a lock nut 36. The tip end 38 of the piston rod 30 passes through the rod cover 222 and protrudes to the outside. In this case, the seal member 27 is fitted into the groove 25 surrounding the through hole 23 of the cover 222.

On the other hand, inside the piston 26 there are
As shown in the figure, a plurality of communicating passages 40 are formed at predetermined intervals in the circumferential direction to communicate the working chambers 2Fla, 28b with each other. Three rods 42 are connected to each other in the three communication paths 40 in the communication IM path 40.
° Slidingly penetrating with deflection. The rod 42 has ring-shaped valve bodies 44a, 4 located on both sides of the piston 26.
4b are slidably inserted and supported through three rod insertion holes 45a and 45b formed in the circumferential direction, and the opening and closing of the numerous communication passages 40 described above are controlled by these valve bodies 44a and 44b. It is configured as follows.

Next, ring-shaped spring receivers 48a and 48b having flanges 46a and 46b extending outward from the piston 26 are fixed to both ends of the rod 42. The valve bodies 44a, 44b and spring receivers 48a, 4
Coil springs 50a and 50b are interposed between the valve bodies 44a and 8b to surround the three rods 42, respectively.
4b is urged in the valve closing direction, that is, toward the piston 26 side. In this case, the coil spring 50a,
The spring loads of 50b are selected to be the same,
Further, in the middle part of the rod 42, there are two flanges 52a located in the communication passage 40 of the piston 26 and spaced apart by a predetermined distance.
, 52b are provided.

Further, in this embodiment, ring-shaped seal members 54a, 54 are provided at the tube side openings of the cover members 22a, 22b.
b are fitted and fixed. The diameters of the seal members 54a and 54b are selected so that they can come into sliding contact with the cushion rings 34a and 34b, respectively. In addition, the cover 22a,
22b has respective ports 24a, 24b and an operating chamber 28a.
, 28b are defined, and each communication path 58a, 58b has an orifice 56a,
56b is provided.

It will be easily understood that the so-called cushion chamber described in FIG. 1 is defined at the end of the tube 20 near the stroke end of the piston 26 by these.

The cylinder shock absorbing device according to the present invention is basically constructed as described above, and its operation and effects will be explained next.

Now, when one boat 24a is communicated with a compressed air supply source such as a compressor by a solenoid valve (not shown), and the other boat 24b is communicated with the atmosphere, compressed air is supplied from the one port 24a. The supplied pressure within the working chamber 2Fla increases, and the piston 26 moves in the direction of arrow A in FIG. As a result, the Tahiston rod 30 coupled to the piston 26 also moves in the same direction. Then, when the piston 26 reaches near the stroke end, the seal member 54b closes the cushion ring 34b.
The air in the cushion chamber defined by the cushion is compressed.

At this time, depending on the length of the rod 42 selected in advance, the flange portion 46b of the spring receiver 48b comes into contact with the end surface of the cover 22b. As a result, as the piston 26 continues to stroke thereafter, the rod 42 integrally connected to the spring receiver 48b moves relative to the piston 26 in the direction of arrow B. As a result, one flange 52a of the rod 42 comes into contact with one of the valve bodies 44a, and the valve body 44a is forcibly opened against the elastic force of one of the coil springs 50a. As a result, the high-pressure compressed air in one of the working chambers 28a flows into the communication passage 40 of the piston 26, and the other valve body 44b is closed so that this compressed air flows into the other working chamber 28b on the low-pressure side. Open the valve.

In this way, from one working chamber 28a to the other working chamber 2
As a result of the compressed air flowing into the piston 8b, as shown in FIG.
The pressure PL and pH of the working chambers 28a and 28b on both sides of the cylinder 6 are controlled to be the same pressure, thereby eliminating the drive energy of the cylinder.

In other words, the energy required when the cylinder stops while pushing the load at the rod tip is the kinetic energy of the load WV2/2g (Formula 1) %Formula % The drive energy of the cylinder π/4・D2・Δp −r,... (Formula 2) However, D
: Tube inner diameter ΔP: Differential pressure L before and after the piston: Obtained by adding the two energies of the cushion stroke. Therefore, as described above, the working chambers 28a, 2F on both sides of the piston 26
If the pressure difference of lb is eliminated, the drive energy of the cylinder can be made zero from the above equation 2, and only the kinetic energy of the load remains.

Therefore, by opening the communication passage 40, the working chambers 28a and 28b on both sides of the piston 26 have the same pressure, and as a result, the cushion chamber, that is, the working chamber 2 on the compression side
8b relatively increases its cushion pressure. For this reason, the kinetic energy of the load is transferred to the cushion chamber 2 described above.
The cushioning function of 8b will be sufficient to deal with this problem. In other words, when the cylinder is driven at high speed and under high load, the differential pressure across the piston 26 increases, and the drive energy increases. However, in the present invention, as described above, the influence of drive energy is eliminated and the ability to absorb kinetic energy is increased by the increased cushion pressure, so this cushion function is sufficient to cope with high speed and high load driving.

On the other hand, just before the stroke end of the piston 26, the coil spring 50 is compressed by the spring receiver 48b.
Since the elastic force of b strongly acts on the other valve body 44b, the valve body 44b is strongly pressed in the valve closing direction and closes the communication passage 40 of the piston 26. As a result, as shown in FIG. 5, immediately before the stroke end of the piston 26, the pressure Pl+ in the other working chamber 28b is lowered to the one working chamber 28a.
The air which is temporarily higher than the internal pressure PL and which has the pressure PR at the end of the stroke is discharged, thereby reducing its pressure and waiting for the next return movement of the piston 26. Note that since it is clear that the same deceleration function as described above can be obtained near the stroke end of the piston 26 when the piston rod 30 is extended, a detailed explanation will be omitted here.

Next, FIG. 6 shows another embodiment of the cylinder shock absorbing device according to the present invention, and the same components as those in the previous embodiment will be described with the same reference numerals.

In this embodiment, the communication path 40 corresponding to the communication path 40 of the previous embodiment is
The passage cross-sectional area of the m passage 61 is increased to form at least one passage for the piston 26, and a rod 62) is individually attached to the communication passage 61, and a ring-shaped valve body (34a, 64b, spring receivers 66a, 66b, and a conical shape) is provided. It is configured to incorporate a valve device consisting of coil springs 68a, 68b, etc.

Also in this embodiment, during a predetermined period near the stroke end of the piston 26, the communication passage 61 is opened by the valve device, and the working chambers 28a and 28 on both sides of the piston 26 are opened.
8b is controlled to the same pressure, and the same deceleration function as in the previous embodiment is obtained.

As explained above, according to the present invention, the piston housed in the tube is provided with a communication passage that communicates the working chambers defined on both sides of the piston, and the communication passage is normally connected by the valve body. The valve body is closed to allow the piston to perform its original operation, and the valve body is opened near the stroke end of the piston to control the working chambers on both sides of the piston to the same pressure, dissipating the drive energy of the cylinder, and dissipating the cylinder's drive energy. It is possible to eliminate the pressure drop and increase the energy absorption capacity during deceleration. As a result, it is possible to smoothly stop the driving of the cylinder not only when the cylinder is driven at low speed and under low load, but also when driven at high speed and under high load. Furthermore, in the present invention, since the buffer mechanism is built into the tube, there is an advantage that the structure of the cylinder can be simplified.

Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to these embodiments, and various improvements and changes in design can be made without departing from the gist of the present invention. Of course.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view of the main parts of a cylinder showing a cushion mechanism, FIG. 2 is a vertical cross-sectional view of a cylinder showing a cylinder speed reduction mechanism according to the present invention, and FIG. 3 is an assembly of the cylinder speed reduction mechanism according to the present invention. Figure 4 is an exploded perspective view of the main part of the cylinder deceleration mechanism according to the present invention, Figure 5 is a characteristic diagram showing the relationship between the piston stroke and cylinder internal pressure, and time. The figure is a sectional view of a main part showing another embodiment of the cylinder speed reduction mechanism according to the present invention. 20...Tube 22a122b...Cover 2
3...Through holes 24a, 24b...Boat 25
... Groove 26... Piston 27... Seal member 28a, 28b... Working chamber 29... Groove 30
...Piston rod 31...Seal ring 32...Base end portions 34a, 34
b...Cushion J-ring 35...Washer 36...Lock nut 38...
・Tip 40...Communication path 42...Rod
44a, 44b... Valve body 45a, 45b... Rod insertion hole 46a, 146b... Flange 48a, 48b... Spring receiver 50a, 50b... Coil spring 52a, 52b... Flange 54a, 54b... Seal member 56a, 56b ... Orifices 58a, 58b - Communication path 61... Communication path 62... Rod 64a164
b...Valve body 55a, 66b...Spring receiver 51'Ja, 68b...Coil spring patent applicant
Sintered Metal Industry Co., Ltd. N!

Claims (4)

[Claims] (1) A piston constituting the cylinder is provided with a communication passage that communicates working chambers defined on both sides of the piston with each other, and a valve device is provided that opens this communication passage under the action of displacement of the piston. Cylinder shock absorber. (2) In the shock absorber according to claim 1,
A cylinder shock absorber in which a plurality of communication passages are formed by penetrating the piston in the axial direction. (3) In the shock absorber according to claim 2,
A cylinder in which a rod is inserted into at least one of a plurality of communication passages, two ring-shaped valve bodies are attached to the rod with a piston in between, and the valve bodies control the opening and closing of all communication passages. shock absorber. (4) In the shock absorber according to claim 1,
A cylinder shock absorber comprising a rod inserted into a communication passage, and a valve body that opens and closes the communication passage by sandwiching a piston between the rods.