JP2002130213A - Cushioning device for pneumatic cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize a cushioning action more when a piston is stopped with shock-absorbing by an air cushion in a pneumatic cylinder. SOLUTION: When a cushion ring 18 communicates with the piston 3 is fit into a depression part 11 at the end of a cylinder tube 2 of the pneumatic cylinder 1, communication with a channel, which discharges air from a discharge side pressure chamber 6A of the piston through the depression part 11, is closed. Thereby, the compressed air in the pressure chamber gives action to the piston 3 the cushioning. In the earlier stage of the cushioning action, the compressed air to act as the cushion in the pressure chamber 6A is discharged directly through a relief valve 21 set in the cushioning channel to the outside. In the later stage of the cushioning action, the compressed air is discharged through the groove 31, forming a throttle channel that is set on the circumference face of the cushion ring 18.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cushion device for a pneumatic cylinder, and more particularly to a cushion device in which a piston speed is mainly reduced by pressure control in a first half of a cushion stroke in which a piston speed is relatively high, and a flow rate is mainly controlled in a second half. The present invention relates to a cushion device capable of performing efficient and shock-free smooth cushioning by two-stage control of decelerating and stopping a piston by control.

[0002]

2. Description of the Related Art Conventionally, as a cushioning mechanism for buffering a piston in a pneumatic cylinder, a cushioning function is applied to the piston by compressed air remaining in an exhaust-side pressure chamber after being compressed by the piston. Is well known. In this cushion mechanism,
A cover provided at the end of the cylinder tube communicates with a supply / discharge port for supplying / discharging compressed air to / from the cylinder, and is open toward the cylinder tube side. When the piston stops, the cushion ring connected to the piston fits into the concave portion, and the direct communication between the exhaust side pressure chamber of the piston and the supply / discharge port communicating with the concave portion is cut off. The compressed air is discharged from the pressure chamber through a needle throttle provided on the cover.

This type of cushion mechanism restricts exhaust by contact between a cushion ring and a cushion packing just before a stroke end of a piston, and absorbs an impact by utilizing the compressibility of air remaining in an exhaust-side pressure chamber. Although a large shock absorbing ability is exhibited, a cushion operation cannot always be stably performed by stopping with a small shock at the stroke end.

For example, when the flow rate is controlled using the needle throttle, if the throttle amount is adapted to the operating conditions of the cylinder, a smooth stop with less impact can be realized. In many cases, an excessive increase in the pressure in the exhaust-side pressure chamber is caused. In such a case, it is difficult to achieve a stop with a small impact at the stroke end. It is usual to bounce once and reduce the piston speed to hit the stroke end. By adjusting the needle throttle, it is possible to cause the piston to perform a somewhat stable buffer stop, but the cushion operation must always be stably performed in accordance with the cylinder operating conditions such as pressure fluctuation, load fluctuation, and speed fluctuation. It is difficult.

On the other hand, it is also possible to discharge the compressed air in the pressure chamber by pressure control through the relief valve. In this case, the pressure in the exhaust side pressure chamber is reduced to the set pressure of the relief valve.
Although the piston can be decelerated effectively, it is generally susceptible to the influence of back pressure and the like, and the opening and closing behavior of the valve seat by the valve body becomes unstable. This problem is caused by a balanced relief valve in which no back pressure acts on the valve body (Japanese Patent Laid-Open No. 7-71420).
In this case, the pressure control according to the pressure in the exhaust side pressure chamber is performed, so that the behavior of the valve body can be stabilized.
It is difficult to sufficiently cope with fluctuations in use conditions.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and its technical problem is basically that when a piston in a pneumatic cylinder is stopped by an air cushion. An object of the present invention is to provide a cushion device that further stabilizes its cushioning action. Another technical object of the present invention is to provide a cushion device which is efficient and can cope with cylinder operating conditions such as load fluctuation, pressure fluctuation and speed fluctuation as much as possible. A more specific technical problem of the present invention is that, when a piston is cushioned by an air cushion, a pressure control that exerts an effective cushioning ability in the first half and a flow control that realizes a smooth stop with less impact in the second half. It is an object of the present invention to provide a cushion device capable of obtaining a stable cushion action by using the cushion device together.

[0007]

According to the present invention, there is provided a cushion device in which the driving of a piston in a pneumatic cylinder is stopped in a buffered manner by compressed air which is compressed and remains in an exhaust-side pressure chamber. In a cushion device, a cover is provided at an end of a cylinder tube, a cushion gasket is attached to an opening opening to the cylinder tube side, and a recess having a flow path for discharging compressed air is provided, and is provided continuously with the piston. When the cushion ring fits into the recess and the direct communication between the exhaust-side pressure chamber of the piston and the discharge passage communicating with the recess is cut off, the compressed air in the pressure chamber acts on the piston to cushion the piston. A cushion flow path for directly discharging compressed air from the exhaust side pressure chamber to the outside. A relief valve is provided, and the cushion ring is provided with a groove for forming a throttle channel between the cushion ring and the cushion ring or a hole for forming a throttle channel communicating with the recess through the cushion ring. Things.

[0008] In the cushion device having the above-described structure, the cushion ring connected thereto is fitted into the cushion packing by driving the piston, and the cushion packing is brought into close contact with the cushion ring, so that the exhaust-side pressure chamber of the piston and the discharge flow are discharged. When the direct communication with the passage is interrupted, the air pressure in the pressure chamber increases due to the subsequent movement of the piston, but the compressed air in the pressure chamber is discharged to the outside through the relief valve. The pressure in the pressure chamber drops to the set pressure of the relief valve, and the compressed air at the set pressure gives a cushion effect to the piston. This relief valve has a large effect in terms of absorbing the kinetic energy of the piston. By installing the relief valve before the cushion stroke, an effective cushioning action is provided in the initial stage of the cushion stroke.

After the cushioning action by the relief valve, the compressed air in the exhaust-side pressure chamber is discharged to the outside through the groove in the portion where the cushion packing is provided with the groove forming the throttle channel on the peripheral surface of the cushion ring. In addition, the flow control can realize a smooth stop with less impact.

In general, in the preceding stage of the cushion stroke in which the piston speed is relatively high, the behavior of the piston is decelerated without causing disturbance such as bouncing by the pressure control. Pressure fluctuations are small, so flow rate control
Smooth cylinder behavior with less impact can be obtained under wider conditions such as pressure, load, and speed. And
By using the pressure control in the first half and the flow rate control in the second half in this way, it is possible to further stabilize the cushioning action of the piston when it stops buffering, and to improve the efficiency, load fluctuation, pressure fluctuation, speed fluctuation, etc. Can be obtained as much as possible.

In the above cushion device, the relief valve is provided with a valve seat provided in a cushion flow path for discharging compressed air from the pressure chamber to the outside, and a valve body pressed against the valve seat by the urging force of the relief pressure adjusting mechanism. And a pressure action chamber for applying the air pressure from the exhaust side pressure chamber of the cylinder tube in the valve opening direction of the valve body, and the acting force of the air pressure flowing through the valve seat on the valve body is upstream and downstream of the valve seat. In this case, it is effective to make the valve body substantially the same, and in this case, since the acting force of the air pressure on the valve body does not change between the upstream side and the downstream side of the valve seat, the valve body has Pressure control according to the pressure of the exhaust-side pressure chamber is performed without being affected by the pressure and the like, and the behavior of the valve body can be stabilized.

Further, in the cushion device, a groove provided on the peripheral surface of the cushion ring is provided with a cross-section that enlarges the cross-section of the flow path at a later stage of the cushioning operation and then gradually narrows the flow path toward the stroke end. By forming a throttle corresponding to the piston position suitable for controlling the behavior of the piston, it is possible to realize a cylinder cushion mechanism that is highly efficient and can cope with load fluctuations, pressure fluctuations, speed fluctuations, and the like. . Even when the pneumatic cylinder is used in a low-speed range where the pressure in the exhaust-side pressure chamber does not increase so much, a smooth cushion effect can be obtained by the action of the throttle corresponding to the piston position.

Further, in the above cushion device,
Cushion packing provided at the opening of the cover of the cylinder tube, by connecting the discharge flow path opened in the recess provided in the cover to the supply / discharge port for supplying and discharging compressed air,
Only the supply from the supply / discharge port to the pressure chamber side can be made possible, whereby compressed air for driving the piston can be supplied to the pressure chamber in the cylinder tube through the supply / discharge port, and the cushion can be supplied. The compressed air in the exhaust-side pressure chamber used for the operation can also be discharged through the supply / discharge port, so that the apparatus can be simplified. However, the supply / discharge flow path can be arbitrarily set, for example, by supplying compressed air to the pressure chamber in the cylinder tube from another supply port.

In the cushion device, a flow path is formed between the pressure chamber in the cylinder tube and the supply / discharge port provided on the cover or an exhaust port provided separately, and a variable throttle valve is provided in the flow path. It is also possible to provide a cushion action by the variable throttle valve to the above-described cushion action in the entire cushion stroke of the piston, and to provide a variety of control of the cushion action according to the operating conditions of the cylinder. Can be granted. Further, a plurality of holes communicating with the inside of the concave portion through the inside of the cushion ring can be formed in a plurality in the moving direction of the piston on the cushion ring.

[0015]

1 to 4 show a pneumatic cylinder according to a first embodiment provided with a cushion device according to the present invention. The pneumatic cylinder 1 includes a cylinder tube 2 and a piston 3 inserted into the cylinder tube 2 and driven by compressed air. The compressed air is supplied to the covers 4A at both ends of the cylinder tube 2,
The air is supplied to and discharged from the pressure chambers 6A and 6B in the cylinder tube 2 defined by the piston 3 from the supply and discharge ports 5A and 5B respectively provided in the piston 4B. The piston 3 includes a piston rod 7, which penetrates a rod cover 4A in a gas-tight manner and extends to the outside.

The pneumatic cylinder 1 is provided with a cushion device for stopping the driving of the piston 3 in a buffered manner by the compressed air remaining in the exhaust-side pressure chamber after being compressed by the piston 3. The cushion device is provided with covers 4A, 4A at both ends of the cylinder tube 2.
B, since they are formed as having the same structure with symmetry, only the cover 4A side will be described here, and the description of the other will be omitted. However, in essence, this cushion device can be provided at only one end of the cylinder tube 2.

In this cushion device, basically, a recess 11 which opens to the cylinder tube 2 side is provided in a cover 4A at an end of the cylinder tube 2, and a cushion packing 12 is attached to an opening of the recess 11; The supply / drain port 5 opened on the outer surface of the cover 4A is provided in the recess 11.
A at the stroke end is opened in the piston 3 at the stroke end.
Into the recess 11 between the cushion packing 12 and
The cushion ring 18 that closes the opening is provided continuously. As a result, the piston 3 moves rightward in FIG. 1, and the cushion ring 18 fits into the concave portion 11,
Exhaust-side pressure chamber 6A partitioned by piston 3 and concave portion 1
When direct communication with the supply / discharge flow path 14 through 1 is cut off, the compressed air in the pressure chamber 6A provides a cushion effect to the piston 3.

Exhaust side pressure chamber 6A in the cushion stroke
Of compressed air is performed by means described below. First, the cover 4A is provided with a cushion flow path 20 that opens directly to the pressure chamber 6A even when the cushion ring 18 closes the recess 11;
As clearly shown in the figure, a relief valve 21 is provided in the cushion flow passage 20, and compressed air having a pressure equal to or higher than a set pressure in the relief valve 21 pushes the relief valve 21 out of the pressure chamber 6A to allow the air to flow through the cover 4A. The air is discharged to the outside via the hole 13, the concave portion 11, the flow path 14, and the supply / discharge port 5A.

The relief valve 21 communicates with the cushion flow path 20, and a pressure adjustment spring 24 is formed by a valve seat 22 through which compressed air flows from the cushion flow path 20 and an adjustment screw 25.
And a valve body 23 pressed against the valve seat 22 by a relief pressure adjusting mechanism capable of adjusting the urging force of
Through the through hole 26 in the valve body 23, the cushion flow path 2
A pressure action chamber 27 for introducing air pressure from zero to the valve body 23 in a direction in which the valve body 23 opens the valve body 23; The balance type is substantially equal between the upstream side and the downstream side of the seat 22. When it is not necessary to consider the influence of the back pressure on the relief valve, it is not necessary to use the above-mentioned balanced relief valve.

On the other hand, a groove 31 is formed on the peripheral surface of the cushion ring 18 so as to form a throttle flow path between the cushion ring 12 and the cushion packing 12 at a later stage of the cushioning operation. As clearly shown in FIG. 4, the groove 31 has a cross section at a position near the piston 3 of the cushion ring 18 where the cross section of the flow path is enlarged once and then the flow path is gradually narrowed toward the stroke end (piston side). However, a configuration in which the throttle that changes in accordance with the piston position is formed late in the cushioning action is more effective for smoothly stopping the piston 3.

However, the present invention is not limited to the groove 31 whose cross section changes as described above, and as shown in the second embodiment of FIG. 5, a groove having a constant cross section over the entire length of the cushion ring 18A having the same function as the cushion ring 18. Alternatively, a groove having a cross section that gradually narrows the flow path can be formed. The groove 32 controls the discharge of the compressed air from the exhaust-side pressure chamber 6A together with the relief valve 21 in the first half of the cushioning action. At this stage, the action of the pressure control mainly by the relief valve 21 remarkably appears, In the latter period, the flow control mainly by the groove 32 plays a major role in the cushion action. That is, in the preceding stage of the cushion stroke in which the piston speed is relatively high, the piston is efficiently decelerated mainly by the pressure control by the above-described relief valve 21, but in the latter stage of the cushion stroke in which the piston speed becomes low, the above-mentioned groove 31 is mainly used.
Alternatively, a smooth cylinder behavior with less impact is obtained under a wider range of conditions such as pressure, load, speed, etc.

In the first embodiment shown in FIGS. 1 to 4, the flow path 34 directly opening to the pressure chamber 6A in the cylinder tube 2 and the flow path 35 connecting the flow path to the recess 11 in the cover 4A. The pressure chamber 6A communicates with the recess 11 of the cover 4A, and a variable throttle valve 36 composed of a needle valve is provided between the flow paths 34 and 35. Since the recess 11 communicates with the supply / discharge port 5A, the flow path 35 consequently discharges the compressed air from the pressure chamber 6A to the outside. Therefore, the flow path 35 is provided separately from the exhaust port. Can also be directly communicated with.

The variable throttle valve 36 has a piston 3
In the entire cushion stroke, the cushioning action of the variable throttle valve is added to the cushioning action described above, whereby it is possible to impart variety to the control of the cushioning action according to the operating conditions of the cylinder. . That is, as shown in FIG. 6, when the flow path cross-sectional area of the variable throttle valve 36 is appropriately set with respect to the flow path cross-sectional area S of the groove 31 which changes according to the cushion stroke, the groove 3
1 and the variable throttle valve 36, the total flow path cross-sectional area is S ₁ , S ₂
Therefore, it is possible to impart variety to the cushioning action by selecting the cross-sectional area of these flow paths. However, these flow paths 34 and 35 and the variable throttle valve 3
6 is not necessarily provided.

The flow path 14 opening into the concave portion 11 provided in the cover 4A can be provided with a supply port for a pressure chamber for exhausting the flow path. The communication with the supply / discharge port 5 </ b> A is advantageous in simplifying the structure. In this case, cover 4
Cushion packing 1 provided at the opening of concave portion 11 of A
2, the pressure chamber 6 is connected to the supply / discharge port 5A as shown in FIG.
It is preferable that only the supply to the A side be made possible, and a supply path of the compressed air to the pressure chamber for driving the piston 3 be secured. When the supply port is provided separately from the exhaust port, it is not necessary to use the cushion packing as described above, and the compressed air may be supplied from the supply port to the pressure chamber via the check valve. Reference numeral 38 in FIG. 1 is a damper provided on both sides of the piston.

In the cushion device having the above structure, the cushion ring 18 is fitted into the cushion packing 12 by driving the piston 3 to the left in FIG.
When the direct communication between the exhaust-side pressure chamber 6A and the concave portion 11 is interrupted, the movement of the piston 3 causes the pressure chamber 6A to move.
Although the air pressure in the pressure chamber rises, the compressed air in the pressure chamber is discharged to the outside through the relief valve 21, so that the pressure in the pressure chamber 6A drops to the set pressure of the relief valve, and the set pressure is reduced. The compressed air exerts a cushioning effect on the piston. By using the relief valve 21 for discharging the compressed air at a stage prior to the cushion stroke, an effective cushioning action is provided in an initial stage of the cushion stroke.

After the cushioning action by the relief valve 21, in the portion of the peripheral surface of the cushion ring 18 where the groove 31 forming the throttle flow path is provided, the compressed air in the exhaust side pressure chamber 6A is discharged to the outside through the groove. In addition, the flow control can realize a smooth stop with less impact. By using the pressure control in the first half and the flow rate control in the second half in this way, it is possible to further stabilize the cushioning action of the piston when it stops buffering, and to improve the efficiency, load fluctuation, pressure fluctuation, speed fluctuation, etc. Can be obtained as much as possible.

In the cushion device of the first embodiment described above, a groove 31 for forming a throttle flow path is provided on the peripheral surface of the cushion ring 18 so as to give an analog flow path cross-sectional change to the cushion stroke. However, instead of the groove 31, as in the third embodiment shown in FIG. 7, a plurality of holes 43a to 43d for forming a throttle channel along the moving direction of the piston 3 on the cushion ring 18B. Opened,
These holes are passed through converging holes 44 and 45 provided in the cushion ring 18B and the piston rod 7, and are opened to the peripheral surface of the piston rod 7 by the holes 46. When the cushion ring 18B protrudes into the concave portion, the compressed air sealed in the pressure chamber 6A flows from the holes 43a to 43d opened in the pressure chamber into the converging holes 44,4.
5 to flow into the recess 11. Therefore, it can be said that the holes 43a to 43d give a digital flow path cross-sectional area change to the analog flow path cross-sectional area change groove 31.

When the grooves 31 and 32 are provided in the cushion ring 18 or 18A as in the first and second embodiments described above, when the depth of those grooves is reduced, the cushion packing 12 resiliently operates. Although a part of the groove is easily filled, it is difficult to secure an accurate opening area. However, in the porous method as in the third embodiment, the opening area can be reduced or the opening area can be accurately secured. It is particularly suitable for micro flow control when the pressure chamber volume is small with a small diameter.

The same holes 43a to 43d as described above are provided in the cushion ring 18B also on the pressure chamber 6B side. However, the holes 44 which merge them and flow out to the concave portion 11 are simply provided at the end face of the cushion ring. It should just be opened to. In addition, since other configurations and operations in the third embodiment are substantially the same as those in the first embodiment, they are denoted by the same reference numerals in the drawings, and description thereof will be omitted.

[0030]

According to the cushion device of the present invention described in detail above, the cushion action is further stabilized and the efficiency is improved, and the load fluctuation, the pressure fluctuation, and the speed are improved when the cushion of the piston in the pneumatic cylinder is stopped by the air cushion. It is possible to provide a cushion device capable of responding to cylinder operating conditions such as fluctuations as much as possible.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a cushion device according to the present invention.

FIG. 2 is a plan view of the same.

FIG. 3 is a sectional view taken along a line AA in FIG.

FIG. 4 is a sectional view of a main part in the embodiment.

FIG. 5 is a perspective view of a main part of a second embodiment of the present invention.

FIG. 6 is a diagram illustrating the operation of the variable throttle valve according to the first embodiment.

FIG. 7 is a sectional view of a main part according to a third embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pneumatic cylinder 2 Cylinder tube 3 Piston 4A, 4B Cover 5A, 5B Supply / discharge port 6A, 6B Pressure chamber 7 Piston rod 11 Recess 12 Cushion packing 18, 18A, 18B Cushion ring 21 Relief valve 22 Valve seat 23 Valve body 27 Pressure action Chambers 31, 32 Grooves 36 Variable throttle valves 43a to 43d holes

Claims (6)

[Claims] The driving of the piston of a pneumatic cylinder, which is inserted into a cylinder tube and driven by compressed air, is stopped in a buffered manner by compressed air remaining therein in the exhaust-side pressure chamber. A cushion device comprising: a cushion at an end portion of a cylinder tube, a cushion packing attached to an opening opening to the cylinder tube side, and a recess having a flow path for discharging compressed air, the cushion being connected to a piston. When the ring fits into the recess and the direct communication between the exhaust-side pressure chamber of the piston and the discharge passage communicating with the recess is cut off, the compressed air in the pressure chamber causes a cushion effect on the piston. In the cushion device, the compressed air is discharged directly from the exhaust-side pressure chamber to the outside. A relief valve is provided, wherein the cushion ring is provided with a groove for forming a throttle flow path between the cushion packing and a hole for forming a throttle flow path communicating with the recess through the cushion ring. Cushion device in a pneumatic cylinder. A relief valve provided in a cushion flow path for discharging compressed air from the pressure chamber to the outside; a valve body pressed against the valve seat by a biasing force of a relief pressure adjusting mechanism;
A pressure action chamber for applying air pressure from the exhaust-side pressure chamber of the cylinder tube in the valve opening direction of the valve body, and acting on the valve body of air pressure flowing through the valve seat between the upstream side and the downstream side of the valve seat. The cushioning device for a pneumatic cylinder according to claim 1, wherein the cushioning device is substantially equal. 3. A groove provided on a peripheral surface of a cushion ring is provided with a cross-section in which a flow path cross-section is enlarged at a later stage of a cushioning operation and then gradually narrows the flow path toward a stroke end. A cushion device for a pneumatic cylinder according to claim 1 or 2. 4. A discharge passage opening in a recess provided in the cover is communicated with a supply / discharge port for supplying / discharging compressed air, and a cushion packing provided in an opening of the cover of the cylinder tube is supplied / discharged. 4. The cushion device according to claim 1, wherein only the supply from the port to the pressure chamber side is enabled. 5. A valve according to claim 1, wherein a flow path is formed between the pressure chamber in the cylinder tube and an exhaust port provided in the cover, and a variable throttle valve is provided in the flow path. A cushion device for a pneumatic cylinder according to any one of the above. 6. The cushion device for a pneumatic cylinder according to claim 1, wherein a plurality of holes communicating with the recess through the cushion ring are formed in the direction of movement of the piston on the cushion ring.