JP6780820B2 - Air cylinder - Google Patents

Description

The present invention relates to an air cylinder, particularly an air cylinder having a small piston sliding resistance.

Conventionally, it has been common technical knowledge that a piston of an air cylinder is provided with a piston packing that slides on the inner surface of the cylinder tube in order to mutually airtightly hold two air chambers provided on both sides of the piston. Due to the presence of this piston packing, it is inevitable that sliding resistance due to the sealing action will be generated when the piston is driven.

By the way, when the piston moves in one direction and the other direction of the piston, that is, in the pushing direction and the pulling direction of the piston rod, which do not require a large output, the two air chambers are communicated with each other outside the air cylinder. There are known technologies for reducing air consumption.

For example, Patent Document 1 describes an actuator drive device that collects and accumulates a part of exhaust discharged from a pressure chamber on the drive side of a double-acting cylinder device in an accumulator and uses it as a return power of the double-acting cylinder device. Has been done.

Jitsufuku No. 2-2965

Regarding the technology of the drive device for returning the fluid pressure cylinder by reusing such exhaust pressure, the applicant has applied to the drive device for the purpose of shortening the time required for recovery and simplifying the fluid circuit. A patent application was filed for the invention (Japanese Patent Application No. 2016-184211). According to the present invention, by providing a check valve or the like in the fluid circuit, a part of the fluid accumulated in one cylinder chamber is supplied to the other cylinder chamber in the return step, and the fluid is supplied to one cylinder chamber. It discharges the other part of the accumulated fluid to the outside.

The present invention has been made in the background of the above techniques, and an object of the present invention is to provide an air cylinder that reduces sliding resistance when a piston moves and suppresses air consumption as much as possible.

The air cylinder according to the present invention includes a cylinder tube, a head cover, a rod cover, a piston, and a piston rod, and has a cylinder chamber defined by a piston into a first air chamber and a second air chamber, and has a first air chamber. A first port for supplying and discharging air from the rod cover is provided on the rod cover, and a second port for supplying and discharging air from the second air chamber is provided on the head cover, and the meter-out control is applied to the air cylinder. There is no seal between the piston and the cylinder tube, and the piston has a first seal member that can contact the rod cover and block the communication between the first port and the second air chamber, and the head cover. It is characterized in that a second seal member capable of contacting and blocking communication between the second port and the first air chamber is provided.

According to the air cylinder, since there is no piston packing that is in sliding contact with the cylinder tube, it is possible to reduce the sliding resistance when the piston moves. Further, at the stroke end of the piston, wasteful discharge of air can be prevented, and the piston can be held at the stroke end position with sufficient thrust.

In the air cylinder, the first seal member is attached to an annular first recess provided on the axial end surface of the piston facing the rod cover, and the rod is elastically deformed with the annular base housed in the first recess. It has an annular lip portion that can be pressure-contacted with the end face of the cover, and the second seal member is mounted on an annular second recess provided on the axial end face of the piston facing the head cover and is housed in the second recess. It has an annular base and an annular lip that can be pressed against the end face of the head cover by elastic deformation . According to this, the attachment structure of the first seal member and the second seal member to the piston becomes simple.

In this case, an annular convex portion facing the bottom surface of the first concave portion is formed so as to protrude from the bottom portion of the base portion of the first sealing member, and the bottom portion of the base portion of the second sealing member faces the bottom surface of the second concave portion. It is preferable that the annular convex portion is formed so as to protrude. According to this, the blocking effect between the first port and the second air chamber by the first sealing member can be enhanced, and the blocking effect between the second port and the first air chamber by the second sealing member can be enhanced. it can.

Further, the first recess and the second recess have a shape narrower on the opening side than on the bottom surface side, and the base portion of the first seal member and the base portion of the second seal member have the bottom side following these shapes. It preferably has a bulging shape. According to this, it is possible to prevent the first seal member from coming out of the first recess, and it is possible to prevent the second seal member from coming out of the second recess.

Furthermore, it is preferable that the first seal member includes a raised portion that abuts on the rod cover and exerts a cushioning action, and the second seal member includes a raised portion that abuts on the head cover and exerts a cushioning action. According to this, the impact can be mitigated at the stroke end of the piston.

Further, it is preferable that a wear ring is attached to the outer circumference of the piston. According to this, the piston can be reliably supported by the bearing with respect to the cylinder tube while ensuring mutual communication between the first air chamber and the second air chamber.

According to the air cylinder according to the present invention, it is possible to eliminate the piston packing, which has been indispensable in the past, and reduce the sliding resistance when the piston moves. Further, although the piston packing is eliminated, wasteful discharge of air can be prevented at the stroke end of the piston, and the piston can be held at the stroke end position with sufficient thrust. As will be described later, according to the air cylinder according to the present invention, the amount of air consumed when the piston reciprocates is equivalent to that of a conventional air cylinder provided with piston packing.

It is sectional drawing of the air cylinder which concerns on embodiment of this invention. It is an enlarged sectional view of the part A of the air cylinder of FIG. It is an enlarged sectional view of the part A part of the air cylinder of FIG. 1 when a piston reaches one stroke end. It is an enlarged sectional view of the part A part of the air cylinder of FIG. 1 when a piston reaches the other stroke end.

Hereinafter, a suitable embodiment of the air cylinder according to the present invention will be described and described in detail with reference to the accompanying drawings. In FIG. 1, reference numeral 10 indicates an air cylinder according to an embodiment of the present invention.

The air cylinder 10 is used, for example, at a work transfer position or the like, and works when the piston rod 20 is pushed out or pulled in. As shown in FIG. 1, the air cylinder 10 includes a cylinder tube 12, a head cover 14, a rod cover 16, a piston 18, and a piston rod 20.

The metal cylinder tube 12 is formed in a cylindrical shape. A metal head cover 14 is fixed to one end of the cylinder tube 12 in the axial direction by means such as press-fitting, and a metal rod cover 16 is fixed to the other end of the cylinder tube 12 in the axial direction by means such as press-fitting. Has been done.

The rod cover 16 is formed in a substantially cylindrical shape, and has a through hole 22 penetrating in the axial direction of the rod cover 16 and a first port 24 extending in a direction perpendicular to the axis of the rod cover 16. A female screw 25 as a pipe connecting portion is provided at one end of the first port 24, and one end of the first port 24 opens to the outer surface of the rod cover 16. The other end of the first port 24 communicates with the through hole 22.

A rod packing 26 is attached to the through hole 22 of the rod cover 16 via a concave groove at a position farther from the piston 18 than the first port 24, and the rod packing 26 is in sliding contact with the piston rod 20. A small diameter portion 28 is formed at the axial end portion of the rod cover 16 facing the piston 18 via a stepped surface, and the other end portion of the cylinder tube 12 in the axial direction is fitted to the outside of the small diameter portion 28. A first seal ring 30 is attached to the small diameter portion 28 of the rod cover 16 via a concave groove, and the first seal ring 30 comes into contact with the inner surface of the cylinder tube 12.

The head cover 14 is formed in a substantially bottomed cylindrical shape, and has a bottomed hole 32 extending in the axial direction of the head cover 14 and a second port 34 extending in a direction perpendicular to the axis of the head cover 14. A female screw 35 as a pipe connecting portion is provided at one end of the second port 34, and one end of the second port 34 opens to the outer surface of the head cover 14. The other end of the second port 34 communicates with the bottomed hole 32.

A small diameter portion 36 is formed at the axial end of the head cover 14 facing the piston 18 via a stepped surface, and one end of the cylinder tube 12 in the axial direction is fitted to the outside of the small diameter portion 36. A second seal ring 38 is attached to the small diameter portion 36 of the head cover 14 via a concave groove, and the second seal ring 38 comes into contact with the inner surface of the cylinder tube 12.

Both ends of the cylinder tube 12 in the axial direction are closed by the rod cover 16 and the head cover 14, and a cylinder chamber 40 is formed inside the cylinder tube 12. The cylinder chamber 40 is divided into a first air chamber 42 on the rod cover 16 side and a second air chamber 44 on the head cover 14 side by the piston 18. The first air chamber 42 is sealed from the outside by the rod packing 26 and the first seal ring 30, and the second air chamber 44 is sealed from the outside by the second seal ring 38.

One end of the metal piston rod 20 is connected to the metal piston 18 by means such as caulking, and the other end of the piston rod 20 extends to the outside through the through hole 22 of the rod cover 16. The first air chamber 42 communicates with the first port 24 through a gap formed between the piston rod 20 and the inner wall of the through hole 22 of the rod cover 16.

A variable throttle valve (speed controller) (not shown) capable of adjusting the flow rate of air discharged from the first air chamber 42 is provided on the opening end side of the first port 24. Similarly, a variable throttle valve (not shown) capable of adjusting the flow rate of the air discharged from the second air chamber 44 is provided on the open end side of the second port 34. These variable throttle valves may be fixed throttle valves. In short, so-called meter-out control is applied to the air cylinder 10.

As shown in FIG. 2, a resin wear ring 46 is mounted on the outer periphery of the piston 18 having a circular cross section via a concave groove. The wear ring 46 is a member that prevents metal touch between the piston 18 and the cylinder tube 12 and is provided as a bearing of the piston 18. A predetermined clearance is secured between the wear ring 46 and the cylinder tube 12. No piston packing is attached to the outer circumference of the piston 18. As a result, the first air chamber 42 and the second air chamber 44 communicate with each other through a gap formed between the piston 18 and the cylinder tube 12. It should be noted that this gap can serve as a flow path resistance when air flows between the first air chamber 42 and the second air chamber 44.

An annular first recess 48 having a predetermined depth is provided on the axial end surface of the piston 18 facing the rod cover 16, and an annular first seal member 50 is mounted on the first recess 48. Similarly, an annular second recess 52 having a predetermined depth is provided on the axial end surface of the piston 18 facing the head cover 14, and an annular second seal member 54 is mounted on the second recess 52. ..

Since the first seal member 50 and the second seal member 54 have basically the same configuration, the configuration of the first seal member 50 will be mainly described below, and the configuration of the second seal member 54 will be described in detail. Is omitted. A is added to the end of the reference code of each component of the first seal member 50, and b is added to the end of the reference code of each component of the second seal member 54 corresponding thereto.

The first sealing member 50 is made of an elastic resin material. The first seal member 50 has an annular base portion 56a housed in the first recess 48 of the piston 18, an annular lip portion 58a extending from the base portion 56a, and an annular raised portion 60a connected to the base portion 56a. The lip portion 58a extends obliquely from the base portion 56a in the axial direction and the radial direction outward of the piston 18. The raised portion 60a protrudes from the first recess 48 in the radial direction of the piston 18 with respect to the lip portion 58a. When no external force is applied to the lip portion 58a, the tip of the lip portion 58a protrudes toward the rod cover 16 from the raised portion 60a. An annular protrusion 62a having a semicircular cross section is formed so as to protrude from the bottom portion of the base portion 56a facing the bottom surface of the first recess 48.

The inner peripheral wall surface 64a constituting the first recess 48 is parallel to the axial direction of the piston 18, whereas the outer peripheral wall surface 66a constituting the first recess 48 is from the bottom surface of the first recess 48. As the distance increases, the piston 18 is inclined toward the axis of the piston 18. In other words, the first recess 48 is narrower on the opening side than on the bottom surface side. The base portion 56a of the first seal member 50 has a shape that bulges toward the bottom, following the shape of the first recess 48. However, with the first seal member 50 housed in the first recess 48, there is a predetermined gap between the outer circumference of the base portion 56a of the first seal member 50 and the wall surface 66a on the outer circumference side of the first recess 48. It is formed. As a result, the annular first seal member 50 can be easily attached to the first recess 48 by utilizing its elasticity, and the first seal member 50 housed in the first recess 48 can be mounted from the first recess 48. It is prevented from coming out. The first seal member 50 can move slightly in the direction parallel to the axis of the piston 18 within a range that does not come out of the first recess 48.

The raised portion 60a of the first sealing member 50 can come into contact with the end surface of the rod cover 16. When the raised portion 60a of the first sealing member 50 comes into contact with the end surface of the rod cover 16, the wall surface 64a on the inner peripheral side of the first recess 48 is substantially aligned with the wall surface of the through hole 22 of the rod cover 16 (FIG. 3). reference). The raised portion 60b of the second seal member 54 can come into contact with the end surface of the head cover 14. When the raised portion 60b of the second seal member 54 comes into contact with the end surface of the head cover 14, the wall surface 64b on the inner peripheral side of the second recess 52 is substantially aligned with the wall surface of the bottomed hole 32 of the head cover 14 (see FIG. 4). ).

The air cylinder 10 according to the present embodiment is basically configured as described above, and its operation will be described below with reference to FIGS. 1, 3 and 4. For convenience, as shown in FIG. 1, the initial state is a state in which the piston 18 is stopped at approximately the same distance from the head cover 14 and the rod cover 16.

From this initial state, a switching valve (not shown) is activated to connect the second port 34 to the air supply source (not shown) and the first port 24 to the exhaust port (not shown). Then, since high-pressure air is supplied from the air supply source to the second air chamber 44, the piston 18 starts moving in the direction of pushing out the piston rod 20.

Here, since the first air chamber 42 is connected to the exhaust port via a throttle valve that limits the flow rate in the exhaust direction, when the piston 18 moves in the direction of pushing out the piston rod 20, the first air chamber 42 As the volume becomes smaller, back pressure is applied to the first air chamber 42. Moreover, since the cross-sectional area of the first air chamber 42 is smaller than the cross-sectional area of the second air chamber 44 due to the presence of the piston rod 20, the pressure of the second air chamber 44 is larger than the pressure of the first air chamber 42. Even if it is small, the piston 18 can move in the direction of pushing out the piston rod 20. Therefore, as the piston 18 moves, the pressure in the first air chamber 42 becomes higher than the pressure in the second air chamber 44. Since the first air chamber 42 and the second air chamber 44 communicate with each other through the gap between the piston 18 and the cylinder tube 12, each time the piston 18 moves, the first air chamber 42 A part of the air flows into the second air chamber 44. Another part of the air in the first air chamber 42 is discharged to the outside through the first port 24 and the throttle valve.

As shown in FIG. 3, when the piston 18 reaches the stroke end in the direction of pushing out the piston rod 20, the first seal member 50 comes into contact with the end surface of the rod cover 16. Specifically, the lip portion 58a is elastic until the lip portion 58a of the first seal member 50 is pushed against the rod cover 16 and the raised portion 60a of the first seal member 50 abuts on the rod cover 16 with a predetermined pressing force. Deform. Then, the tip of the lip portion 58a comes into pressure contact with the end surface of the rod cover 16 with a predetermined sealing pressure over the entire circumference of the lip portion 58a. At this time, the annular protrusion 62a of the first seal member 50 is pressed against the bottom surface of the first recess 48 of the piston 18 with a predetermined seal pressure over the entire circumference thereof.

When the raised portion 60a of the first seal member 50 comes into contact with the rod cover 16 at the stroke end of the piston 18, it acts as a cushion to cushion the impact. Even if the raised portion 60a comes into contact with the rod cover 16, there is a clearance between the raised portion 60a and the rod cover 16.

When the lip portion 58a of the first sealing member 50 is pressed against the end surface of the rod cover 16 and the annular protrusion 62a of the first sealing member 50 is pressed against the bottom surface of the first recess 48 of the piston 18, it is the narrowest at the stroke end. The first air chamber 42 is airtightly partitioned into a first region 68 and a second region 70 (see FIG. 3). The first region 68 communicating with the first port 24 through the gap formed between the piston rod 20 and the inner wall of the through hole 22 of the rod cover 16 is formed between the piston 18 and the cylinder tube 12. It is cut off from the second region 70 that communicates with the second air chamber 44 through the gap.

Then, since the piston 18 stops at the stroke end, the back pressure due to the throttle valve is eliminated, and the gap between the first port 24, the piston rod 20 and the through hole 22 of the rod cover 16 and the pressure in the first region 68 are reduced. It becomes lower than the pressure of the second air chamber 44 and the second region 70. Therefore, after the piston 18 reaches the stroke end in the direction of pushing out the piston rod 20, even if the piston 18 stays in that position stably and high-pressure air is supplied to the second air chamber 44, the first port 24 Air is not discharged from. As a result, it is possible to prevent wasteful consumption of air. Further, a sufficient thrust can be applied to the piston 18 to hold the piston rod 20 in the most extruded position.

After that, the switching valve is activated to connect the first port 24 to the air supply source (not shown) and the second port 34 to the exhaust port (not shown). Then, since high-pressure air is supplied from the air supply source to the first air chamber 42, the piston 18 starts to move in the direction of pulling in the piston rod 20, and the first seal member 50 separates from the rod cover 16.

Here, since the second air chamber 44 is connected to the exhaust port via a throttle valve that limits the flow rate in the exhaust direction, when the piston 18 moves in the direction in which the piston rod 20 is pulled in, the second air chamber 44 As the volume becomes smaller, back pressure is applied to the second air chamber 44. However, when the piston 18 moves in the direction in which the piston rod 20 is pulled in, the pressure in the second air chamber 44 will not be higher than the pressure in the first air chamber 42 unless the flow rate limiting effect of the throttle valve is so large. .. That is, the pressure of the first air chamber 42 continues to be higher than the pressure of the second air chamber 44. Therefore, when the piston 18 moves in the direction in which the piston rod 20 is pulled in, a part of the air in the first air chamber 42 is between the piston 18 and the cylinder tube 12 in a state where the flow rate limiting effect of the throttle valve is not so large. It flows into the second air chamber 44 through the gap of.

As shown in FIG. 4, when the piston 18 reaches the stroke end in the direction in which the piston rod 20 is pulled in, the second seal member 54 comes into contact with the end surface of the head cover 14. Specifically, the lip portion 58b of the second seal member 54 is pushed against the head cover 14, and the lip portion 58b is elastically deformed until the raised portion 60b of the second seal member 54 abuts on the head cover 14 with a predetermined pressing force. .. Then, the tip of the lip portion 58b comes into pressure contact with the end surface of the head cover 14 with a predetermined sealing pressure over the entire circumference of the lip portion 58b. At this time, the annular protrusion 62b of the second seal member 54 is pressed against the bottom surface of the second recess 52 of the piston 18 with a predetermined seal pressure over the entire circumference thereof.

The raised portion 60b of the second seal member 54 acts as a cushion to cushion the impact when it comes into contact with the head cover 14 at the stroke end of the piston 18. Even if the raised portion 60b comes into contact with the head cover 14, there is a clearance between the raised portion 60b and the head cover 14.

When the lip portion 58b of the second seal member 54 is pressed against the end surface of the head cover 14, and the annular protrusion 62b of the second seal member 54 is pressed against the bottom surface of the second recess 52 of the piston 18, it becomes the narrowest at the stroke end. The second air chamber 44 is airtightly partitioned into the first region 72 and the second region 74 (see FIG. 4). The first region 72 communicating with the second port 34 through the bottomed hole 32 of the head cover 14 communicates with the first air chamber 42 through a gap formed between the piston 18 and the cylinder tube 12. It is blocked from the area 74.

Therefore, after the piston 18 reaches the stroke end in the direction in which the piston rod 20 is pulled in, even if high-pressure air is supplied to the first air chamber 42, the air is not discharged from the second port 34. As a result, it is possible to prevent wasteful consumption of air. Further, a sufficient thrust can be applied to the piston 18 to hold the piston rod 20 in the most retracted position.

After that, when the switching valve is activated and the second port 34 is connected to the air supply source (not shown) and the first port 24 is connected to the exhaust port (not shown), the second seal member After the 54 is separated from the head cover 14, the state shifts to the same state as when the first switching valve described above is operated. After that, the same operation is repeated.

According to the present embodiment, since the piston 18 is not provided with the piston packing that is in sliding contact with the cylinder tube 12, the sliding resistance when the piston 18 is moved can be reduced. Further, after the piston 18 reaches each stroke end in the piston rod 20 pushing direction and the piston rod 20 pulling direction, wasteful discharge of air is prevented, and a sufficient thrust is applied to the piston 18 to cause the piston rod 20 to move. It can be held at the stroke end position.

The applicant applies for air leakage by providing a clearance between the outer circumference of the piston and the inner circumference of the cylinder tube in an air cylinder provided with throttle valves for meter-out control on the first port side and the second port side, respectively. Was raised, and a test was conducted on the amount of air consumed when air was circulated in the cylinder chamber.

As a result, it was found that both the flow rate of the air supplied and the flow rate of the discharged air in the process of moving the piston in the direction of pushing out the piston rod are smaller than those in the case where the piston has no air leakage. The rate of decrease tends to increase as the clearance between the piston and the cylinder tube increases, and as the moving speed of the piston decreases.

It was also found that both the flow rate of air supplied and the flow rate of discharged air in the process of moving the piston in the direction of pulling in the piston rod are higher than those in the case where the piston has no air leakage. The rate of increase tends to increase as the clearance between the piston and the cylinder tube increases, and as the moving speed of the piston decreases.

Furthermore, the combined flow rate of the air supplied in the process of moving the piston in the direction of pushing out the piston rod and the flow rate of air supplied in the process of moving the piston in the direction of pulling in the piston rod leaks to the piston. It turned out to be equivalent to the case without. Similarly, the combined flow rate of air discharged in the process of moving the piston in the direction of pushing out the piston rod and the flow rate of air discharged in the process of moving the piston in the direction of pulling in the piston rod is the flow rate of air to the piston. It turned out to be equivalent to the case without leakage.

As can be seen from the above test results, the amount of air consumed by the air cylinder according to the present invention is equivalent to that of a conventional air cylinder provided with piston packing.

It goes without saying that the air cylinder according to the present invention is not limited to the above-described embodiment and may have various configurations as long as the gist of the present invention is not deviated.

10 ... Air cylinder 12 ... Cylinder tube 14 ... Head cover 16 ... Rod cover 18 ... Piston 20 ... Piston rod 24 ... 1st port 34 ... 2nd port 40 ... Cylinder chamber 42 ... 1st air chamber 44 ... 2nd air chamber 46 ... Wearing 48 ... 1st recess 50 ... 1st seal member 52 ... 2nd recess 54 ... 2nd seal member 56a, 56b ... Base 58a, 58b ... Lip 60a, 60b ... Rise 62a, 62b ... Circular protrusion

Claims (5)

It includes a cylinder tube, a head cover, a rod cover, a piston, and a piston rod, and has a cylinder chamber defined by the piston into a first air chamber and a second air chamber, and supplies and discharges air from the first air chamber. A first port for supplying and discharging air from the second air chamber is provided on the rod cover, and a second port for supplying and discharging air from the second air chamber is provided on the head cover, and meter-out control is applied to the air cylinder.
The piston and the cylinder tube are not sealed, and the piston has a first seal member capable of contacting the rod cover and blocking communication between the first port and the second air chamber. , A second seal member capable of contacting the head cover and blocking communication between the second port and the first air chamber is provided .
The first seal member is attached to an annular first recess provided on the axial end surface of the piston facing the rod cover, and the rod is elastically deformed with an annular base housed in the first recess. The second sealing member has an annular lip portion that can be pressure-contacted with the end surface of the cover, and the second seal member is attached to an annular second recess provided on the axial end surface of the piston facing the head cover, and the second recess is provided. An air cylinder characterized by having an annular base housed in the head cover and an annular lip portion that can be pressure-welded to the end face of the head cover by elastic deformation . In the air cylinder according to claim 1 ,
An annular convex portion facing the bottom surface of the first recess is formed so as to project from the bottom of the base of the first sealing member, and the bottom of the base of the second sealing member faces the bottom surface of the second recess. An air cylinder characterized in that an annular convex portion is projected. In the air cylinder according to claim 1 ,
The first recess and the second recess have a shape narrower on the opening side than on the bottom surface side, and the base of the first seal member and the base of the second seal member follow these shapes. An air cylinder characterized by a bulging shape on the bottom side. In the air cylinder according to claim 1 ,
The first seal member includes a raised portion that abuts on the rod cover and exerts a cushioning action, and the second seal member includes a raised portion that abuts on the head cover and exerts a cushioning action. Cylinder. In the air cylinder according to claim 1,
An air cylinder characterized in that a wear ring is mounted on the outer circumference of the piston.

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