JP6796291B2 - Air cylinder - Google Patents

Description

The present invention relates to an air cylinder, and more particularly to an air cylinder that does not require a large driving force when pushing out a piston rod.

Conventionally, there has been known a drive device for a double-acting actuator using air pressure, which requires a large output in a drive process and does not require a large output in a return process (see Patent Document 1).

Jitsufuku No. 2-2965

This actuator drive device collects and accumulates a part of the exhaust gas discharged from the drive side pressure chamber of the double-acting cylinder device in the accumulator, and uses it for the return power of the double-acting cylinder device. Specifically, when the switching valve is switched, the high-pressure exhaust gas in the drive-side pressure chamber is accumulated in the accumulator through the recovery port of the recovery valve. When the exhaust pressure drops and the difference between the exhaust pressure and the accumulator pressure becomes smaller, the residual air in the drive side pressure chamber is released to the atmosphere from the discharge port of the recovery valve, and at the same time, the accumulator pressure accumulated air flows into the return side pressure chamber. To do.

Even if the switching valve is switched, the actuator drive device does not release the high-pressure air in the drive side pressure chamber to the atmosphere until the difference between the exhaust pressure and the accumulator pressure becomes small, so it is necessary for the double-acting cylinder device to return. It takes time to obtain thrust. It also requires a recovery valve with a complex structure.

Therefore, the applicant has invented a drive device for reusing the exhaust pressure to return the fluid pressure cylinder, for the purpose of shortening the time required for the return and simplifying the fluid circuit. (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.

In addition, the applicant has filed a patent application for an invention of an air cylinder designed so that the reference resistance of the fluid circuit is determined by the piping and reducing the air consumption by reducing the diameter of the piping (Japanese Patent Application No. 2017-165113). ).

The present invention has been made in connection with these patent applications, and an object of the present invention is to provide an air cylinder capable of reducing air consumption while maintaining the same configuration as the conventional fluid circuit. And.

In the air cylinder according to the present invention, there is no first air chamber and piston rod in which the other end of the piston rod, one end of which is connected to the piston, extends to the outside through the rod cover and the piston rod is longitudinally traversed by the piston. It has a cylinder chamber defined as two air chambers, and the first port for supplying and discharging the air in the first air chamber and the second port for supplying and discharging the air in the second air chamber are in the cylinder body. In the process of moving the piston in the direction of pushing out the piston rod in the air cylinder provided and to which the meter-out control is applied, the first air chamber and the second air chamber communicate with each other and the piston rod is pulled in. In the process of moving the piston, the piston is provided with a passage structure in which communication between the first air chamber and the second air chamber is cut off, and the passage structure is formed with a through hole formed in the axial direction of the piston. The opening / closing piston is provided in the through hole so as to be movable in the axial direction of the piston, and when the opening / closing piston is in a predetermined position with respect to the through hole, the opening / closing piston is provided. It is characterized in that the first air chamber and the second air chamber communicate with each other through a communication hole formed inside the piston .

According to the above air cylinder, in the process of moving the piston in the direction of pushing out the piston rod, a part of the air in the first air chamber is not discharged to the outside but flows into the second air chamber, so that the air consumption is reduced. Can be planned. Further, the piston has a passage structure in which the first air chamber and the second air chamber are communicated with each other in the process of pushing out the piston rod and the communication between the first air chamber and the second air chamber is cut off in the process of pulling in the piston rod. Can be easily incorporated into.

Further, the opening / closing piston abuts on the rod cover near the stroke end where the piston moves in the direction of pushing out the piston rod, and the stopper fixed to the opening / closing piston is near the stroke end where the piston moves in the direction of pulling in the piston rod. It is preferable to abut the end cover portion of the cylinder body. According to this, it is possible to reliably switch between a state in which the first air chamber and the second air chamber communicate with each other at the stroke end of the piston and a state in which the communication between the first air chamber and the second air chamber is cut off. Can be done.

According to the air cylinder according to the present invention, in the process of moving the piston in the direction of pushing out the piston rod, a part of the air in the first air chamber is not discharged to the outside but flows into the second air chamber, so that the fluid circuit has a fluid circuit. It is possible to reduce air consumption while maintaining the same configuration as before.

It is sectional drawing of the air cylinder which concerns on 1st Embodiment of this invention. It is an enlarged sectional view of the part A of the air cylinder of FIG. It is sectional drawing when the air cylinder of FIG. 1 is in a different operating state. It is the B part enlarged sectional view of the air cylinder of FIG. It is sectional drawing of the air cylinder of FIG. 1 when a piston reaches one stroke end. It is sectional drawing 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.

As shown in FIG. 1, the air cylinder 10 has a cylinder body 12, a piston 14, a piston rod 16, and a rod cover 18. The air cylinder 10 is used, for example, in a device for clamping a work, exerts a required driving force when the piston rod 16 is pulled in, and works, and does not work when the piston rod 16 is pushed out. That is, the step of moving the piston 14 in the direction of pulling in the piston rod 16 is the driving step, and the step of moving the piston 14 in the direction of pushing out the piston rod 16 is the returning step.

The cylinder body 12 is formed in a bottomed cylindrical shape in which one end is closed by the end cover portion 20. The rod cover 18 is fixed to the inner circumference of the other end side of the cylinder body 12 by the locking ring 22, whereby the cylinder chamber 24 is formed inside the cylinder body 12. One end of the piston rod 16 is connected to the piston 14, and the other end of the piston rod 16 extends outward through the rod cover 18.

The first sealing material 26 is mounted on the outer peripheral surface of the rod cover 18 via a concave groove, and the first sealing material 26 comes into contact with the inner peripheral surface of the cylinder body 12. A second sealing material 28 is mounted on the inner peripheral surface of the rod cover 18 via a concave groove, and the second sealing material 28 is in sliding contact with the outer peripheral surface of the piston rod 16. The cylinder chamber 24 is externally sealed by the first sealing material 26 and the second sealing material 28.

The cylinder chamber 24 is divided by the piston 14 into a first air chamber 30 through which the piston rod 16 traverses the inside and a second air chamber 32 in which the piston rod 16 does not exist. As shown in FIG. 2, a piston packing 34 is mounted on the outer peripheral surface of the piston 14 via a concave groove, and the piston packing 34 is in sliding contact with the inner peripheral surface of the cylinder body 12. In FIG. 2, the member represented by reference numeral 36 is a wear ring.

The cylinder body 12 is provided with a first port 38 that communicates with the first air chamber 30 to supply and discharge air to the first air chamber 30, and also communicates with the second air chamber 32 to the second air chamber 32. A second port 40 for supplying and discharging air is provided.

A variable throttle valve (speed controller) (not shown) that can adjust the flow rate of the air discharged from the first air chamber 30 is attached to the first port 38 side. Similarly, a variable throttle valve (not shown) capable of adjusting the flow rate of the air discharged from the second air chamber 32 is provided on the second port 40 side. These variable throttle valves may be fixed throttle valves. In short, so-called meter-out control is applied to the air cylinder 10.

Next, the passage structure 42 including the opening / closing piston 50 will be described with reference to FIGS. 2 and 4. In the step of moving the piston 14 in the direction of pushing out the piston rod 16, the passage structure 42 is a step of communicating the first air chamber 30 and the second air chamber 32 with each other and moving the piston 14 in the direction of pulling in the piston rod 16. Then, it is provided to cut off the communication between the first air chamber 30 and the second air chamber 32.

The piston 14 is formed with a through hole 44 penetrating in the axial direction of the piston 14. The through hole 44 includes a first large-diameter hole portion 44a that opens on one surface in the axial direction of the piston 14, a second large-diameter hole portion 44b that opens on the other surface in the axial direction of the piston 14, and a first. It has a small-diameter hole portion 44c that connects the large-diameter hole portion 44a and the second large-diameter hole portion 44b. A first stepped surface 46 is formed at the boundary between the first large-diameter hole portion 44a and the small-diameter hole portion 44c, and a second stepped surface 48 is formed at the boundary portion between the second large-diameter hole portion 44b and the small-diameter hole portion 44c. Is formed.

An opening / closing piston 50 is provided in the through hole 44 of the piston 14 so as to be movable in the axial direction of the piston 14. The opening / closing piston 50 has a large-diameter piston portion 52 and a small-diameter rod portion 54. The piston portion 52 can be inserted into the first large-diameter hole portion 44a of the piston 14, and can be brought into contact with the first stepped surface 46 of the piston 14. When the piston portion 52 comes into contact with the first stepped surface 46 of the piston 14, the piston portion 52 is housed in the first large-diameter hole portion 44a without protruding from the first large-diameter hole portion 44a of the piston 14. (See FIG. 4). That is, the end face of the piston portion 52 is aligned with the end face of the piston 14 in a state where the piston portion 52 is in contact with the first stepped surface 46 of the piston 14. A seal member 56 is mounted on the outer periphery of the piston portion 52 via a concave groove, and the seal member 56 can be slidably contacted with the first large-diameter hole portion 44a of the piston portion 14.

The rod portion 54 of the opening / closing piston 50 is inserted into the small diameter hole portion 44c of the piston 14. The rod portion 54 has a communication hole 58 for communicating the first air chamber 30 and the second air chamber 32 with each other. The communication hole 58 has a lateral hole 58a that crosses in a direction perpendicular to the axis of the rod portion 54 and both ends open to the side surface of the rod portion 54, and one end that extends in the axial direction of the rod portion 54 and one end of the rod portion 54. Includes a vertical hole 58b that opens into the portion and the other end communicates with the lateral hole 58a.

A cylindrical stopper 60 is fixed to the end of the rod portion 54 of the opening / closing piston 50 by means such as press fitting or welding. The stopper 60 has a disc portion 62 and a tubular portion 64 that rises from the outer peripheral edge of the disc portion 62 toward the rod portion 54 by a predetermined length and covers the end portion of the rod portion 54. The outer diameter of the tubular portion 64 is smaller than the inner diameter of the second large-diameter hole portion 44b of the piston 14, and the tubular portion 64 can be inserted into the second large-diameter hole portion 44b. The end surface of the tubular portion 64 can come into contact with the second stepped surface 48 of the piston 14, so that the opening / closing piston 50 does not come out of the through hole 44 of the piston 14. The disk portion 62 projects by a predetermined length from the end surface of the piston 14 in a state where the end surface of the tubular portion 64 is in contact with the second stepped surface 48 (see FIG. 2). The opening / closing piston 50 is located between a position where the piston portion 52 abuts on the first step surface 46 of the piston 14 and a position where the tubular portion 64 of the stopper 60 abuts on the second step surface 48 of the piston 14. Can be moved against.

An opening hole 66 communicating with the vertical hole 58b of the rod portion 54 of the opening / closing piston 50 is formed in the center of the disk portion 62 of the stopper 60. As shown in FIG. 4, when the piston portion 52 of the opening / closing piston 50 is housed in the first large-diameter hole portion 44a of the piston 14 and the seal member 56 is in contact with the first large-diameter hole portion 44a, the first The air chamber 30 and the second air chamber 32 are airtightly partitioned from each other, and air communication is cut off between them.

On the other hand, as shown in FIG. 2, when the piston portion 52 of the opening / closing piston 50 protrudes from the first large-diameter hole portion 44a of the piston 14 and the seal member 56 is separated from the first large-diameter hole portion 44a, the first The 1 air chamber 30 is formed with a gap formed between the first large-diameter hole 44a of the piston 14 and the opening / closing piston 50, the communication hole 58 of the rod portion 54, and the second air through the opening hole 66 of the stopper 60. It communicates with the room 32. The gap formed between the first large-diameter hole portion 44a of the piston 14 and the opening / closing piston 50, the communication hole 58 of the rod portion 54, and the opening hole 66 of the stopper 60 are formed when the piston 14 moves. It can be a flow path resistance when air flows between the first air chamber 30 and the second air chamber 32.

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 to 6. As shown in FIG. 5, the initial state is the state in which the piston rod 16 is in the most pushed position.

In the initial state, the piston 14 comes into contact with the rod cover 18, the piston portion 52 of the opening / closing piston 50 is housed in the first large-diameter hole portion 44a of the piston 14, and the seal member 56 is housed in the first large-diameter hole portion 44a. It is in contact. Therefore, the communication of air between the first air chamber 30 and the second air chamber 32 is cut off.

From this initial state, a switching valve (not shown) operates to connect the first port 38 to the air supply source (not shown) and the second port 40 to the exhaust port (not shown). Then, high-pressure air is supplied from the air supply source to the first air chamber 30, and the air in the second air chamber 32 is restricted to a predetermined flow rate by the throttle valve provided on the second port 40 side and discharged to the outside. Will be done. As a result, the piston 14 is driven in the direction in which the piston rod 16 is pulled in, and a predetermined thrust acting on the piston 14 performs work such as clamping the work (see FIG. 3).

In the driving process in which the piston rod 16 is pulled in, when the piston 14 reaches the vicinity of the stroke end, the stopper 60 of the opening / closing piston 50 comes into contact with the end cover portion 20 of the cylinder body 12. As a result, the stopper 60 is pushed by the end cover portion 20, and opens and closes integrally with the stopper 60 until the end surface of the tubular portion 64 of the stopper 60 comes into contact with the second step surface 48 of the piston 14 and the piston 14 reaches the stroke end. The piston 50 moves in the through hole 44 of the piston 14 in the axial direction.

At the stroke end of the piston 14 in the drive process shown in FIG. 6, the seal member 56 is separated from the first large-diameter hole portion 44a of the piston 14. That is, the first air chamber 30 is provided with the second air through the gap between the first large-diameter hole portion 44a of the piston 14 and the opening / closing piston 50, the communication hole 58 of the rod portion 54, and the opening hole 66 of the stopper 60. It communicates with the room 32. From this state, the switching valve operates, the second port 40 is connected to the air supply source, and the first port 38 is connected to the exhaust port.

Then, since high-pressure air is supplied from the air supply source to the second air chamber 32, the piston 14 starts moving in the direction of pushing out the piston rod 16. Since the first air chamber 30 is connected to the exhaust port via a throttle valve that limits the exhaust flow rate, when the piston 14 moves in the direction of pushing out the piston rod 16, the volume of the first air chamber 30 becomes smaller. , Back pressure is applied to the first air chamber 30. Moreover, since the cross-sectional area of the first air chamber 30 is smaller than the cross-sectional area of the second air chamber 32 due to the presence of the piston rod 16, the pressure of the second air chamber 32 is larger than the pressure of the first air chamber 30. Even if it is small, the piston 14 can move in the direction of pushing out the piston rod 16. Therefore, as the piston 14 moves, the pressure in the first air chamber 30 becomes higher than the pressure in the second air chamber 32. Since the first air chamber 30 and the second air chamber 32 communicate with each other, a part of the air in the first air chamber 30 flows into the second air chamber 32 each time the piston 14 moves. Another part of the air in the first air chamber 30 is discharged to the outside through the first port 38 and a throttle valve (not shown).

In the return step in which the piston rod 16 is pushed out, when the piston 14 reaches the vicinity of the stroke end, the piston portion 52 of the opening / closing piston 50 comes into contact with the rod cover 18. As a result, the piston portion 52 is pushed by the rod cover 18 and accommodated in the first large-diameter hole portion 44a, and the opening / closing piston 50 is held in the piston 14 until the piston 14 abuts on the rod cover 18 and reaches the stroke end. Moves in the through hole 44 in the axial direction.

At the stroke end of the piston 14 in the return step, the seal member 56 is in contact with the first large diameter hole 44a, and the air communication is cut off between the first air chamber 30 and the second air chamber 32. .. This is the same state as the initial state, and the same operation is repeated thereafter.

According to the present embodiment, in the return step in which the piston rod 16 is pushed out, a part of the air in the first air chamber 30 is not discharged to the outside but flows into the second air chamber 32, so that the air consumption is reduced. be able to.

In the present embodiment, the opening / closing piston 50 is incorporated into the through hole 44 formed in the piston 14 at only one place. However, a plurality of through holes 44 are formed in the piston 14, and the opening / closing piston 50 is formed in each through hole 44. It may be configured to incorporate. When a plurality of sets of through holes 44 and opening / closing pistons 50 are provided, it is preferable to arrange them at equidistant positions from the axis of the piston 14 and at equal intervals in the circumferential direction. By arranging in this way, the piston 14 can be supported by the end cover portion 20 in a well-balanced manner by the plurality of stoppers 60 at the stroke end of the piston 14 in the driving process.

Further, although the rod portion 54 of the opening / closing piston 50 has been described as being simply inserted into the small diameter hole portion 44c of the piston 14, the opening / closing piston 50 moves into the first air chamber 30 and the second air chamber 32 when the piston rod 16 is pushed out. A frictional force may act between the rod portion 54 and the small-diameter hole portion 44c so that the rod portions 54 and the small-diameter hole portions 44c are stably held at positions where they communicate with each other.

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 described above, when the first air chamber and the second air chamber are communicated with each other, the air consumption decreases in the process of moving the piston in the direction of pushing out the piston rod, but the piston moves in the direction of pulling in the piston rod. On the contrary, the air consumption increases in the process. As in the present invention, the first air chamber and the second air chamber are communicated with each other in the process of moving the piston in the direction of pushing out the piston rod, and the piston moves in the direction of pulling in the piston rod with the first air chamber. It can be seen that the air consumption can be effectively reduced by cutting off the communication with the second air chamber.

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 body 14 ... Piston 16 ... Piston rod 18 ... Rod cover 20 ... End cover part 24 ... Cylinder chamber 30 ... First air chamber 32 ... Second air chamber 38 ... First port 40 ... Second port 42 ... Passage structure 44 ... Through hole 50 ... Opening / closing piston 58 ... Communication hole 60 ... Stopper

Claims (2)

The other end of the piston rod whose one end is connected to the piston extends to the outside through the rod cover, and the piston rod is vertically traversed by the piston into a first air chamber and a second air chamber where the piston rod does not exist. It has a defined cylinder chamber, and the cylinder body is provided with a first port for supplying and discharging air from the first air chamber and a second port for supplying and discharging air from the second air chamber. An air cylinder to which meter-out control is applied.
In the step of moving the piston in the direction of pushing out the piston rod, the first air chamber and the second air chamber communicate with each other, and in the step of moving the piston in the direction of pulling in the piston rod, the first The piston is provided with a passage structure in which communication between the air chamber and the second air chamber is cut off .
The passage structure includes a through hole formed in the axial direction of the piston and an opening / closing piston provided in the through hole so as to be movable in the axial direction of the piston, and the opening / closing piston is the said. Air characterized in that the first air chamber and the second air chamber communicate with each other through a communication hole formed inside the opening / closing piston when the air chamber is in a predetermined position with respect to the through hole. Cylinder. In the air cylinder according to claim 1 ,
The opening / closing piston abuts on the rod cover near the stroke end where the piston moves in the direction of pushing out the piston rod, and the stopper fixed to the opening / closing piston is in the direction in which the piston pulls in the piston rod. An air cylinder characterized in that it contacts the end cover portion of the cylinder body in the vicinity of the moving stroke end.

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