JP3466121B2 - Pneumatic cylinder with cushion mechanism - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pneumatic cylinder having a cushion mechanism for absorbing a shock due to inertial energy when a piston stops at the end of a stroke.

[0002]

2. Description of the Related Art In a pneumatic cylinder having a cylinder tube and a piston that slides in the cylinder tube, cushion air is temporarily contained in a pressure chamber on the exhaust side to raise the pressure when the piston is operated, and the pressure is increased. BACKGROUND ART A cushion mechanism that decelerates a piston with atmospheric pressure to stop it at a stroke end in a buffered manner has been conventionally known. In this conventional pneumatic cylinder, the cushion ring provided on the piston side is fitted into the cushion packing in the cylinder tube before the end of the stroke to block the air discharge passage, and this air is guided to the throttle valve, and the throttle adjustment amount is adjusted. Accordingly, the piston back pressure converts the kinetic energy of the piston into the compression energy of air and exerts a deceleration force.

However, in the conventional pneumatic cylinder with a cushion mechanism, due to the structure of the cushion mechanism, a cushion ring having a required length is provided on at least one side of the piston, and a long empty space into which the cushion ring is fitted. It has been pointed out that since it is necessary to provide the cylinder, the length of the cylinder in the axial direction becomes long.

[0004]

SUMMARY OF THE INVENTION The main technical problem of the present invention is to provide a cushion mechanism with a small size, a simple structure and a low cost by eliminating the need for a long cushion ring and a long empty space into which it is fitted. To provide a pneumatic cylinder.

Another technical object of the present invention is to simply provide a means for limiting the exhaust flow rate on the cylinder tube side and a plurality of packings which also serve as piston packings and cushion packings on the piston side. Another object is to provide a pneumatic cylinder with a cushion mechanism having a rational design structure.

[0006]

In order to solve the above problems, a pneumatic cylinder according to the present invention comprises a cylinder tube, a piston that slides in the cylinder tube, and compressed air in two pressure chambers separated by the piston. 2 for feeding and discharging
In a pneumatic cylinder with two ports, the tube wall of the cylinder tube has an opening through the pressure chamber.
The above-mentioned two ports that communicate with each other are provided, and the tube wall is located closer to the tube end than the respective ports .
Two valve chambers formed by the recesses on the outer surface
In the valve chamber, an exhaust port communicating with the pressure chamber is provided.
A throttle mechanism for buffering the piston by limiting the flow rate of the exhaust gas discharged from the pressure chamber to the valve chamber, and a flow of exhaust gas arranged in parallel with the throttle mechanism from the exhaust port toward the port side. the flow of compressed air in the opposite direction to regulate houses check valve you acceptable, the two ports
A plurality of piston packings that communicate with the valve chamber and the two valve chambers via flow passages, respectively, and that are provided on the outer peripheral surface of the piston to partition the two pressure chambers by sliding contact with the inner peripheral surface of the cylinder tube, In these piston packings, the piston packing on the front side in the moving direction gets over the port on the exhaust side immediately before the piston reaches the stroke end,
The exhaust port stops at a position where it does not cross over, and the piston packing on the rear side in the direction of movement is positioned so that it does not cross the opening of the exhaust side port and stops in front of it so that it also functions as a cushion packing. It is characterized by that.

In the pneumatic cylinder having the above structure, the piston is driven in the forward and reverse directions by alternately supplying and discharging compressed air through the two ports, and the deceleration stop by the cushion mechanism at the stroke end is performed as follows. Done. That is, when the piston slides, compressed air in the pressure chamber on the exhaust side is initially discharged through the port, but when the piston approaches the stroke end, the piston packing, which also functions as a cushion packing, closes the port on the exhaust side. When the vehicle gets over, the port and the pressure chamber are shut off, and the compressed air in the pressure chamber is exhausted only from the exhaust port through the throttling mechanism. Therefore, the pressure in the pressure chamber rises due to the flow rate control by the throttle mechanism, which becomes the piston back pressure to decelerate the piston and reach the end of the stroke.

The pneumatic cylinder with the cushion mechanism is
Since it is not necessary to provide a long cushion ring and a long empty space into which the cushion ring is fitted, the length of the cylinder in the axial direction can be shortened by that much, and the pneumatic cylinder can be downsized. In addition, the throttle mechanism for limiting the exhaust flow rate is installed on the cylinder tube side, and a plurality of packings that substantially double as piston packing and cushion packing are installed on the piston side. The pneumatic cylinder can be manufactured at a low cost because of a simple and rational design structure with less.

According to a specific embodiment of the present invention, the
By accommodating the valve member having the throttle mechanism with the lip seal forming the check valve interposed in the valve chamber, they are incorporated in the valve chamber.

[0010]

1 and 2 show a first embodiment of a pneumatic cylinder with a cushion mechanism according to the present invention.
This pneumatic cylinder 1A has a cylinder tube 4 whose both ends are closed by a head cover 6 and a rod cover 8, respectively, a piston 10 that reciprocally slides in the cylinder tube 4, and a piston rod 10a connected to the piston 10. And have.

Two ports 12 and 14 for supplying and discharging compressed air are provided at positions near the head-side and rod-side ends of the cylinder tube 4. These ports 12 and 14 are opened to a pair of pressure chambers 20 and 22 defined on both sides of the piston 10, respectively.
6 and 18 communicate with each other, and these ports 12,
By supplying and exhausting compressed air to and from the pressure chambers 20 and 22 from 14 through the opening, the piston 10 is reciprocally driven in the cylinder tube 4. In addition, the opening 1
Exhaust ports 24 and 26 for discharging cushion air from the pressure chambers 20 and 22 are provided at positions substantially at both ends of the cylinder tube 4 closer to the stroke end side of the piston 10 than 6 and 18. These exhaust ports 24,
Speed adjusting means 28, 30 for deceleratingly stopping the piston by limiting the flow rate of exhaust gas are connected between the valve 26 and the ports 12, 14, respectively.

The speed adjusting means 28 (30) is constituted by arranging the check valve 32 (34) and the throttle mechanism 36 (38) for restricting the flow rate in parallel, and is a valve formed in the cylinder tube 4. It is housed in the chamber 31. That is, the exhaust port 24 (26) in the cylinder tube 4
The exhaust port 24 (26) and the port 1 at a position corresponding to
2 (14), the valve chamber 31 communicating with both of them is formed, and a cylindrical valve member 33 is accommodated in the valve chamber 31, and the valve member 33 is provided with the throttle mechanism 36 (38). A lip seal forming the check valve 32 (34) is interposed between the outer peripheral surface of the valve member 33 and the inner peripheral surface of the valve chamber 31. In the figure, 35 (37) is a bypass flow path connecting the valve chamber 31 and the port 12 (14).

The throttle mechanism 36 (38) is provided with an exhaust port 24.
(26) and the port 12 (14) to the bypass passage 3
5 (37) and a needle 47 for adjusting the opening area of the through hole 45, which is configured as a variable throttle valve. On the other hand, the check valve 32 (34) suppresses the outflow of compressed air from the pressure chamber 20 (22) to the port 12 (14) side in the cushion stroke on the stroke end side of the piston 10 and drives the piston 10. It is provided to allow only the inflow of compressed air from the port 12 (14) into the pressure chamber 20 (22) at the start.

The outer peripheral surface of the piston 10 is in sliding contact with the inner peripheral surface of the cylinder tube 4, and the two pressure chambers 20,
Two piston packings 40 and 42 that partition 22 are provided. These piston packings 40, 42
Not only has the function of partitioning the pressure chambers 20 and 22, but also
The switching function of the exhaust flow path, that is, the compressed air in the pressure chambers 20 and 22 is exhausted through the exhaust port 2 by overcoming the port on the exhaust side immediately before the piston 10 reaches the stroke end.
It also has a function as a cushion packing that operates so that it can be discharged only from ports 4 and 26.
2, 14 and the exhaust ports 24, 26 have the following positional relationship. That is, when the piston 10 slides to the head side or the rod side to reach the end of each stroke, the piston packing 40 on the front side in the moving direction is formed.
Or 42 stops at a position where the opening 16 or 18 of the exhaust side port 12 or 14 gets over but not the exhaust port 24 or 26, and the piston packing 42 or 40 on the rear side in the moving direction moves to the exhaust side port 12 or It is provided in such a positional relationship that it does not go beyond the opening 16 or 18 of the 14 and stops before it.

The operation of the pneumatic cylinder with a cushion mechanism 1A having the above structure will be described in detail with reference to the drawings. In FIG. 1, when compressed air is supplied to one port 12 in the state where the piston 10 is at the stroke end on the head side, the compressed air is supplied to the bypass passage 35.
To the inside of the valve chamber 31, pushes the check valve 32 open, and flows from the exhaust port 24 into the pressure chamber 20 on the head side, so that the piston 10 starts moving toward the rod side (left side in the drawing). When the piston packing 40 on the rear side in the moving direction of the piston 10 exceeds the opening 16 of the port 12, the compressed air is mainly supplied directly to the pressure chamber 20 through the opening 16 and the piston 10 Will continue to move. Along with the movement, the compressed air in the pressure chamber 22 on the rod side is mainly discharged directly from the opening 18 through the port 14.

As shown in FIG. 2, the piston 1
When 0 approaches the stroke end on the rod side and the piston packing 42 on the front side in the moving direction passes through the opening 18 (and therefore the port 14), the pressure chamber 22 on the exhaust side and the port 14 are shut off, and the pressure chamber The compressed air in 22 is discharged from the exhaust port 26 via the throttle mechanism 38 in the speed adjusting means 30. In other words, the piston packing 42 functions as a cushion packing,
The exhaust path is switched from a state in which it is directly discharged through the opening 18 and the port 14 to a state in which it is restrictedly discharged through the exhaust port 26 and the throttle mechanism 38. Therefore, the pressure in the pressure chamber 22 rises due to the flow rate control by the throttle mechanism 38, and it becomes the piston back pressure to decelerate the piston 10 to reach the end of the stroke. At this time, the piston packing 42 on the front side in the moving direction stops before the exhaust port 26, and the piston packing 40 on the rear side moves.
Stops before the opening 18 of the port 14.

In contrast to the above, when the piston 10 is stroked from the rod-side stroke end toward the head-side stroke end, compressed air is supplied to the port 14.
In this case, when the piston 10 approaches the stroke end on the head side, the piston packing 40 on the front side in the moving direction of the piston 10 functions as a cushion packing, and the compressed air discharge path from the head side pressure chamber 20. Is switched from a state in which it is directly discharged through the port 12 to a state in which it is discharged through the exhaust port 24 and the throttle mechanism 36 of the speed adjusting means 28 in a limited manner.
Will stop buffering while decelerating to the head side stroke end.

In the pneumatic cylinder with a cushion mechanism having the above-mentioned structure, it is not necessary to provide a long cushion ring on the piston rod or a long empty chamber into which the cylinder is fitted, unlike the conventional product, so that the cylinder tube 4
The axial length of the cylinder can be shortened by that much, and the pneumatic cylinder can be downsized. Moreover, since the piston packings 40 and 42 substantially have a structure which also functions as a cushion packing, the number of parts of the pneumatic cylinder can be reduced and the structure can be simplified, whereby the pneumatic cylinder can be manufactured at low cost. .

In the figure, 41 is a wear ring and 43 is a magnet for position detection, but these are provided as necessary.

FIG. 3 shows a second embodiment of the present invention.
In the pneumatic cylinder 1B of the second embodiment, the throttle mechanisms 36a and 38a in the speed adjusting means 28 and 30 are connected to the through hole 4
It is different from the first embodiment in that it is formed as a fixed diaphragm whose opening area of 5a cannot be adjusted. Since the configuration and operation other than those described above are substantially the same as those of the first embodiment, the same reference numerals as those of the first embodiment are given to the same major components and the description thereof will be omitted.

[0021]

The pneumatic cylinder with a cushion mechanism of the present invention does not require a long cushion ring and an empty space into which the cushion ring is fitted, so that the length of the cylinder in the axial direction can be shortened accordingly. Can reduce the size of the pneumatic cylinder. Moreover, since the piston packing substantially has a structure that also functions as a cushion packing, the number of parts of the pneumatic cylinder can be reduced and the structure can be simplified, whereby the pneumatic cylinder can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a side cross-sectional view showing a first embodiment of a pneumatic cylinder with a cushion mechanism of the present invention, with only the upper half portion cut away, in a state before starting the piston drive.

FIG. 2 is a side sectional view showing a state of a cushion stroke of the first embodiment.

FIG. 3 is a partial cross-sectional view showing a second embodiment of the present invention with only the upper half portion cut away.

[Explanation of symbols]

1A, 1B, 1C, 1D, 1E Pneumatic cylinder 4 cylinder tube 10 pistons 12, 14 ports 20,22 Pressure chamber 24,26 exhaust port 28,30 Speed adjusting means 31 valve chamber 32,34 Check valve 33 Valve member 36, 36a, 38, 38a Aperture mechanism 40, 42 Piston packing

─────────────────────────────────────────────────── --- Continuation of the front page (56) References JP-A-6-249214 (JP, A) JP-A-10-169608 (JP, A) Actually open 62-69601 (JP, U) Actually open 2- 62101 (JP, U) US Patent 3033169 (US, A) US Patent 4089251 (US, A) West German Utility Model 9418129 (DE, B) (58) Fields investigated (Int.Cl. ⁷ , DB name) F15B 15 /twenty two

Claims (2)

(57) [Claims] 1. A pneumatic cylinder comprising a cylinder tube, a piston sliding in the cylinder tube, and two ports for supplying and discharging compressed air to and from two pressure chambers separated by the piston, Open the pressure chamber on the tube wall of the cylinder tube.
With the above two ports that communicate through the mouth
To, by positioning the tube end nearer respective port Ju
Two valves formed by a recess in the outer surface of the wall
The chamber is provided, in the valve chamber, provided with an exhaust port leading to the pressure chamber, the valve
Stop mechanism for stopping the piston cushioned manner by limiting the flow rate of the exhaust gas discharged from the pressure chamber into the chamber, 及
From being placed in parallel with the fine the narrowed mechanism the exhaust port the compressed air flow in the opposite direction to the exhaust flow toward the port side and restricting accommodating a check valve you acceptable, the two ports and two Through the flow path to the valve chamber
Communicating Te, on the outer peripheral surface of the piston, sliding contact with the inner peripheral surface of the cylinder tube provided with a plurality of piston seal partitioning the two pressure chambers above, their piston packing, the piston reaches the stroke end Immediately before the operation, the piston packing on the front side in the moving direction passes over the port on the exhaust side, but stops at a position where it does not cross the exhaust port, and the piston packing on the rear side in the moving direction does not cross the opening on the port on the exhaust side and A pneumatic cylinder with a cushion mechanism, which is provided in such a positional relationship that it stops at, and thereby also functions as a cushion packing. 2. The pneumatic cylinder according to claim 1, wherein a valve member having a throttle mechanism is housed in the valve chamber with a lip seal forming a check valve interposed therebetween so that the valve member and the valve chamber are housed in the valve chamber. Characterized by being incorporated into.