TWI699488B - Fluid circuit of air cylinder - Google Patents

Abstract

A fluid circuit (20) of an air cylinder (22) partitioned by a first air chamber (42) and a second air chamber (44) by a piston (38) and including a switching valve (30), a first air flow path (24) arranged between the first air chamber and the switching valve, a second air flow path (26) arranged between the second air chamber and the switching valve, a by-pass flow path (28) connecting a midpoint of the first air flow path to a midpoint of the second air flow path, and a check valve (46) and a pilot check valve (48) disposed on the by-pass flow path. The check valve allows air to flow from the second air chamber to the first air chamber and prevents air from flowing from the first air chamber to the second air chamber. The pilot check valve allows air to flow from the first air chamber to the second air chamber and prevents air from flowing from the second air chamber to the first air chamber while a pilot pressure is not applied.

Description

The fluid circuit of the pneumatic cylinder

The present invention relates to a fluid circuit of a pneumatic cylinder, in particular to a fluid circuit of a double-acting pneumatic cylinder that does not require a large driving force in the return phase.

In the past, there has been known a driving device using a double-acting actuator using air pressure that requires a large output during the driving phase and does not require a large output during the return phase (refer to Japanese Utility Model Publication No. 2-2965).

This actuator drive device is as shown in Figure 5, and part of the exhaust gas discharged from the drive side pressure chamber 3 of the double-acting cylinder device 1 is recovered and stored in the accumulator 12 and used as a double-acting cylinder device 1. The power of return. Specifically, when the switching valve 5 is switched to the state shown in FIG. 5, the high-pressure exhaust system in the drive-side pressure chamber 3 passes through the recovery port 10b of the recovery valve 10 and is accumulated in the accumulator 12. When the exhaust pressure decreases and the difference between the exhaust pressure and the pressure of the accumulator becomes smaller, the residual air in the drive side pressure chamber 3 is released from the discharge port 10c of the recovery valve 10 to the atmosphere. At the same time, the pressure accumulator 12 The system flows into the pressure chamber 4 on the return side.

In the actuator drive device described above, even if the switching valve 5 is switched, the high-pressure air in the drive-side pressure chamber 3 will not be released to the atmosphere until the difference between the exhaust pressure and the accumulator pressure is reduced, which takes time. The problem of waiting to obtain the thrust required for the return of the double-acting cylinder device 1. In addition, the recovery valve 10 must be capable of connecting the inlet port 10a of the recovery valve 10 to the recovery port 10b during the period when the pressure difference between the discharge pressure and the accumulator pressure is large, and when the pressure difference between the discharge pressure and the accumulator pressure becomes smaller , Complicated structure connecting the inlet port 10a and the outlet port 10c.

In view of the above-mentioned problems, the applicant filed an invention patent application (Japanese Patent Application No. 2016-253074) concerning a drive device for reusing exhaust pressure to reset a fluid pressure cylinder, with the aim of shortening the time required for the reset. And to simplify the loop.

The invention of the above-mentioned patent application is in the predetermined position of the switching valve, one cylinder chamber is connected to the other cylinder chamber through the check valve and communicates with the exhaust port. At this time, there are two piping from one cylinder chamber to the switching valve, so there is a problem that it takes time and energy to deal with the piping.

The present invention was developed in view of the above matters. The purpose of the present invention is to save energy by reusing the exhaust pressure to reset the pneumatic cylinder, and to shorten the time required for the reset as much as possible, and to reuse the exhaust pressure. Simplify the fluid circuit for resetting the pneumatic cylinder.

In the fluid circuit of the pneumatic cylinder of the present invention, the pneumatic cylinder has a first air chamber and a second air chamber separated by a piston, and the fluid circuit includes: a switching valve; a first air flow path, which is arranged in the first Between the air chamber and the switching valve; the second air flow path is set between the second air chamber and the switching valve; the bypass flow path is connected between the middle point of the first air flow path and the middle of the second air flow path Point; and the check valve and the pilot check valve are set in the bypass flow path. In addition, the check valve allows air to flow from the second air chamber to the first air chamber, and prevents air from passing from the first air chamber to the second air chamber; the guided check valve allows air to flow from the first air chamber The circulation to the second air chamber, and prevents the circulation of air from the second air chamber to the first air chamber when the guiding pressure is not working.

According to the fluid circuit of the pneumatic cylinder, the air accumulated in the second air chamber can be discharged to the outside while being supplied to the first air chamber. Therefore, as the pressure of the first air chamber increases, the pressure of the second air chamber decreases rapidly, and the time required for the return of the pneumatic cylinder can be shortened as much as possible. Furthermore, a complicated recovery valve is not required, and the fluid circuit for the return of the pneumatic cylinder can be simplified.

In the fluid circuit of the pneumatic cylinder, it is preferable that a second check valve is provided in the first air flow path between the intermediate point of the first air flow path and the switching valve, and the second check valve allows air to flow from the first air flow path. The middle point of the air flow path flows to the switching valve, and the flow of air from the switching valve to the middle point of the first air flow path is prevented. The first air flow path between the second check valve and the pilot check valve There is a guiding flow path between the switching valve and the switching valve. When the switching valve is in the first position, the first air flow path is connected to the air supply source, and the second air flow path is connected to the exhaust port; the switching valve is in the second position. In the position, the first air flow path is connected to the exhaust port, and the second air flow path is connected to the air supply source.

According to the above configuration, the number of piping from the pneumatic cylinder side to the switching valve can be minimized, and there is no need to spend time and energy on piping processing. In addition, a simple fluid circuit can reliably cause a pilot pressure above a predetermined pressure to act on the pilot check valve.

In the above-mentioned case, it is preferable that the first air flow path between the first air chamber and the intermediate point of the first air flow path includes a tank portion. According to this structure, the air discharged from the second air chamber can be accumulated in the groove, and the pressure drop of the first air chamber can be suppressed as much as possible when the volume of the first air chamber increases during the return phase of the pneumatic cylinder.

In addition, it is preferable that the bypass flow path and the second check valve are provided inside the pneumatic cylinder, and it is more preferable to provide the second air flow path between the intermediate point of the second air flow path and the switching valve. There is a throttle valve, which is arranged inside the pneumatic cylinder. According to this structure, the fluid circuit of the pneumatic cylinder can be built in the pneumatic cylinder as much as possible.

In addition, it is preferable that the piston rod connected to the piston penetrates the first air chamber longitudinally, and the end of the piston rod extends outside through the rod cover. According to this structure, when the piston rod is driven in the pushing direction, a large thrust can be exerted on the piston.

According to the fluid circuit of the pneumatic cylinder of the present invention, the time required for the return of the pneumatic cylinder can be shortened as much as possible. In addition, since there is no need for a complicated recovery valve, the number of pipes from the pneumatic cylinder to the switching valve can be minimized, so that the fluid circuit for resetting the pneumatic cylinder can be simplified.

From the description of the following preferred embodiments with reference to the drawings, the above objectives, features and advantages should be more clearly understood.

1‧‧‧Double acting cylinder device

3‧‧‧Drive side pressure chamber

4‧‧‧Return side pressure chamber

5.30‧‧‧Switching valve

10‧‧‧Recover valve

10a‧‧‧Entrance port

10b‧‧‧Recycling port

10c‧‧‧Exhaust port

12‧‧‧Pressure accumulator

20‧‧‧Fluid circuit

22‧‧‧Pneumatic cylinder

24‧‧‧First air flow path

24t‧‧‧Slot

26‧‧‧Second air flow path

28‧‧‧Bypass flow path

30A‧‧‧First port

30B‧‧‧Second port

30C‧‧‧Third port

30D‧‧‧Fourth port

30E‧‧‧Port 5

32‧‧‧Cylinder tube

34‧‧‧Hood

36‧‧‧Rod cover

38‧‧‧Piston

40‧‧‧Piston rod

42‧‧‧First air chamber

44‧‧‧Second Air Chamber

46‧‧‧First check valve (check valve)

48‧‧‧Guide check valve

50‧‧‧Second check valve

52‧‧‧Diversion flow path

54‧‧‧Speed Controller

56‧‧‧Air supply source

58a‧‧‧First exhaust port

58b‧‧‧Second exhaust port

M1, M2‧‧‧Intermediate point

Figure 1 is a conceptual circuit diagram of a fluid circuit of a pneumatic cylinder according to an embodiment of the present invention.

Figure 2 is a circuit diagram similar to Figure 1 when the switching valve is at the first position and the piston rod is at the end position on the retracted side.

Figure 3 is a circuit diagram similar to Figure 1 when the switching valve is at the second position and the piston rod is at the end position on the push side.

Figure 4 is an external view of the pneumatic cylinder in Figure 1.

Figure 5 is a circuit diagram of the actuator drive device of the prior art document.

Hereinafter, with respect to the fluid circuit of the pneumatic cylinder of the present invention, preferred embodiments are listed and described with reference to the drawings.

As shown in FIG. 1, the fluid circuit 20 of the pneumatic cylinder in the embodiment of the present invention includes a first air flow path 24, a second air flow path 26, a bypass flow path 28, and a switching valve 30.

As shown in Fig. 4 and the like, the pneumatic cylinder 22 is composed of a cylinder tube 32, a head cover 34, a rod cover 36, a piston 38, a piston rod 40, and the like. One end of the cylinder tube 32 is closed by a rod cover 36, and the other end of the cylinder tube 32 is closed by a head cover 34. The piston 38 is arranged in the cylinder tube 32 in a reciprocating manner. The internal space of the cylinder tube 32 is divided into: a first air chamber 42 formed between the piston 38 and the rod cover 36; and a first air chamber 42 formed in the piston 38 and the second air chamber 44 between the hood 34.

The piston rod 40 connected to the piston 38 traverses the first air chamber 42 longitudinally, and its end is extended to the outside through the rod cover 36. The pneumatic cylinder 22 performs operations such as unillustrated workpiece positioning when the piston rod 40 is pushed out (when it is extended), and does not perform operations when the piston rod 40 is retracted.

A first air flow path 24 is provided between the first air chamber 42 of the pneumatic cylinder 22 and the switching valve 30, and a second air flow path 26 is provided between the second air chamber 44 of the pneumatic cylinder 22 and the switching valve 30. The bypass flow path 28 diverges from the middle of the first air flow path 24, and the bypass flow path 28 merges on the middle of the second air flow path 26. That is, the bypass flow path 28 is provided between the middle point M1 of the first air flow path 24 and the middle point M2 of the second air flow path 26.

In the bypass flow path 28, a first check valve (check valve) 46 is provided on the side close to the midpoint M2 of the second air flow path 26, and a first check valve (check valve) 46 is provided on the side close to the midpoint M1 of the first air flow path 24 Guide check valve 48. The first check valve 46 allows air to flow from the second air chamber 44 to the first air chamber 42 and prevents air from the first air chamber 42 to the second air chamber 44.

The pilot check valve 48 allows air to flow from the first air chamber 42 to the second air chamber 44. In addition, the pilot check valve 48 prevents the flow of air from the second air chamber 44 to the first air chamber 42 when there is no pilot pressure above the predetermined pressure, and when there is a pilot pressure above the predetermined pressure At this time, the circulation of air from the second air chamber 44 to the first air chamber 42 is allowed. In other words, the pilot check valve 48 functions as a check valve when the pilot pressure is not acting, that is, allowing air to flow from the first air chamber 42 to the second air chamber 44 and preventing air from flowing from the second air chamber. 44 circulates to the first air chamber 42, and when the pilot pressure is applied, air can circulate in any direction, and loses its function as a check valve.

A second check valve 50 is provided in the first air flow path 24 between the intermediate point M1 of the first air flow path 24 and the switching valve 30. The second check valve 50 allows air to flow from the intermediate point M1 of the first air flow path 24 to the switching valve 30, and prevents the air from passing from the switching valve 30 to the intermediate point M1 of the first air flow path 24. In addition, a guide flow path 52 which branches from the first air flow path 24 between the second check valve 50 and the switching valve 30 and reaches the guide check valve 48 is provided.

A speed controller 54 is provided in the second air flow path 26 between the intermediate point M2 of the second air flow path 26 and the switching valve 30, and the discharge from the second air chamber 44 can be manually adjusted by the speed controller 54 The flow of air. That is, the speed controller 54 is a so-called meter-out variable throttle valve. By operating the speed controller 54, the ratio of the amount of air accumulated in the second air chamber 44 supplied to the first air chamber 42 and the amount discharged to the outside can be adjusted.

The switching valve 30 has a first port 30A to a fifth port 30E, and is configured as a two-position five-port solenoid valve that can be switched between a first position and a second position. The first port 30A is connected to the first air flow path 24, and the second port 30B is connected to the second air flow path 26. The third port 30C is connected to an air supply source 56. The fourth port 30D is connected to a first exhaust port (exhaust port) 58a with a silencer, and the fifth port 30E is connected to a second exhaust port (exhaust port) 58b with a silencer.

As shown in Figure 2, when the switching valve 30 is in the first position, the first port 30A is connected to the third port 30C, and the second port 30B is connected to the fifth port 30E. On the other hand, as shown in Figure 1, when the switching valve 30 is in the second position, the second port 30B is connected to the third port 30C, and the first port 30A is connected to the fourth port 30D. In the driving stage of the pneumatic cylinder 22 that pushes the piston rod 40 out, the switching valve 30 is switched to the second position, and in the return stage of the pneumatic cylinder 22 that retracts the piston rod 40, the switching valve 30 is switched to the first position .

Fig. 1 is a circuit diagram conceptually showing the fluid circuit 20 of the pneumatic cylinder. In addition, the flow path constructed inside the pneumatic cylinder 22 is also depicted as being arranged outside the pneumatic cylinder 22 as appropriate. Practically speaking, the part surrounded by a chain line in Figure 1 is the bypass flow path 28 containing the first check valve 46 and the pilot check valve 48, and the first containing the second check valve 50 A part of the air flow path 24 and a part of the second air flow path 26 are constructed inside the pneumatic cylinder 22.

The first air flow path 24 between the first air chamber 42 and the intermediate point M1 of the first air flow path 24 includes a groove 24t. The groove portion 24t has a larger volume so as to function as an air groove for accumulating air. For example, the first air flow path 24 in the area surrounded by the one-dot chain line in Figure 1 is provided across the rod cover 36, the cylinder tube 32, and the head cover 34, and the portion provided in the cylinder tube 32 becomes a groove. 24t. The groove portion 24t may be formed by, for example, a space formed between the inner tube and the outer tube in the cylinder tube 32 having a double structure composed of the inner tube and the outer tube.

The fluid circuit 20 of the pneumatic cylinder of this embodiment is basically constructed as described above, and its function is described below with reference to Figs. 2 and 3. In addition, as shown in FIG. 2, the state where the switching valve 30 is in the first position so that the piston rod 40 is most retracted is the initial state.

In this initial state, when the switching valve 30 is switched from the first position to the second position, the high-pressure air from the air supply source 56 is supplied to the second air chamber 44 through the second air flow path 26, and the first air chamber 42 The air inside is discharged from the first exhaust port 58a to the outside through the first air flow path 24 including the second check valve 50.

Thereby, the pressure of the second air chamber 44 starts to rise, and the pressure of the first air chamber 42 starts to fall. When the pressure of the second air chamber 44 exceeds the pressure of the first air chamber 42 and is higher than the static friction force of the piston 38, the piston rod 40 starts to move in the pushing direction. And, as shown in FIG. 3, the piston rod 40 is extended to the maximum position, and is held in its position with a large thrust.

After the piston rod 40 is extended to perform work such as positioning of the workpiece, the switching valve 30 is switched from the second position to the first position. Then, the high-pressure air from the air supply source 56 flows into the first air flow path 24 between the second check valve 50 and the switching valve 30, but the second check valve 50 prevents the flow of the air in the flow path. The pressure of the air rises. In addition, the pressure of the guide flow path 52 connected to the flow path becomes equal to or higher than a predetermined pressure, so that the guide check valve 48 loses its function as a check valve.

When the pilot check valve 48 loses its function as a check valve, a part of the air accumulated in the second air chamber 44 passes through the middle point M2 of the second air flow path 26, and passes through the first check valve 46 and the pilot The bypass flow path 28 of the check valve 48 is supplied to the first air chamber 42 from the midpoint M1 of the first air flow path 24. At the same time, the other part of the air accumulated in the second air chamber 44 is discharged to the outside from the second exhaust port 58b via the second air flow path 26. Thereby, the pressure of the second air chamber 44 starts to drop, and the pressure of the first air chamber 42 starts to rise. At this time, the air supplied to the first air chamber 42 mainly accumulates in the groove portion 24t. This is because before the piston rod 40 starts to retract, the groove portion includes the first air chamber 42 and the bypass flow path 28 between the first check valve 46 and the first air chamber 42 where air can exist. 24t occupies the largest space.

The pressure in the second air chamber 44 decreases, and the pressure in the first air chamber 42 rises. When the pressure in the second air chamber 44 is equal to the pressure in the first air chamber 42, by the action of the first check valve 46, the second The air in the air chamber 44 cannot be supplied to the first air chamber 42 so that the increase in the pressure of the first air chamber 42 stops. On the other hand, the pressure of the second air chamber 44 continues to drop. Moreover, when the pressure of the first air chamber 42 exceeds the pressure of the second air chamber 44 by the static friction force of the piston 38, the piston rod 40 starts to move in the retracting direction.

When the piston rod 40 starts to move in the retracting direction, the volume of the first air chamber 42 increases, so the pressure of the first air chamber 42 drops, but due to the presence of the groove 24t, the volume of the first air chamber 42 becomes substantial The higher the pressure, the lower the pressure drop rate. In addition, since the pressure of the second air chamber 44 drops at a greater rate than that, the state where the pressure of the first air chamber 42 exceeds the pressure of the second air chamber 44 continues. Furthermore, the sliding resistance of the piston 38 once it starts to move is smaller than the frictional resistance of the piston 38 in a stationary state, so that the piston rod 40 can move in the retracting direction without any obstacle. In this way, the piston rod 40 returns to the initial state where it is most retracted. This state is maintained until the switching of the switching valve 30 is performed again.

According to this embodiment, during the return phase of the pneumatic cylinder 22, a part of the air accumulated in the second air chamber 44 can be supplied to the first air chamber 42 through the first check valve 46 and the pilot check valve 48. In addition, the other part of the air accumulated in the second air chamber 44 is discharged to the outside, so the time required for the return of the pneumatic cylinder 22 can be shortened as much as possible.

Furthermore, in the first air flow path 24, a second check valve 50 is provided between the intermediate point M1 of the first air flow path 24 and the switching valve 30, and between the second check valve 50 and the switching valve 30 A guide flow path 52 is provided between the first air flow path 24 and the guide check valve 48. When the switching valve 30 is in the first position, the first air flow path 24 is connected to the air supply source 56. Therefore, a simple fluid circuit can reliably cause a pilot pressure above a predetermined pressure to act on the pilot check valve 48.

Furthermore, the flow path from the side of the pneumatic cylinder 22 to the switching valve 30 has only two flow paths of the first air flow path 24 and the second air flow path 26, so the handling of piping becomes simple. Moreover, since the bypass flow path 28 including the first check valve 46 and the pilot check valve 48, a part of the first air flow path 24 including the second check valve 50, and a part of the second air flow path 26 Since it is constructed inside the pneumatic cylinder 22, the fluid circuit arranged outside the pneumatic cylinder 22 can be reduced as much as possible.

In this embodiment, the speed controller 54 in the second air flow path 26 between the midpoint M2 of the second air flow path 26 and the switching valve 30 is provided outside the air cylinder 22, but also A throttle valve to replace the speed controller 54 may be provided inside the pneumatic cylinder 22, such as the head cover 34.

The fluid circuit of the pneumatic cylinder of the present invention is not limited to the above-mentioned embodiment, and various configurations can be adopted without departing from the gist of the present invention.

20‧‧‧Fluid circuit

24‧‧‧First air flow path

24t‧‧‧Slot

26‧‧‧Second air flow path

28‧‧‧Bypass flow path

30‧‧‧Switching valve

30A‧‧‧First port

30B‧‧‧Second port

30C‧‧‧Third port

30D‧‧‧Fourth port

30E‧‧‧Port 5

38‧‧‧Piston

40‧‧‧Piston rod

42‧‧‧First air chamber

44‧‧‧Second Air Chamber

46‧‧‧First check valve (check valve)

48‧‧‧Guide check valve

50‧‧‧Second check valve

52‧‧‧Diversion flow path

54‧‧‧Speed Controller

56‧‧‧Air supply source

58a‧‧‧First exhaust port

58b‧‧‧Second exhaust port

M1, M2‧‧‧Intermediate point

Claims (5)

A fluid circuit of a pneumatic cylinder. The pneumatic cylinder has a first air chamber and a second air chamber separated by a piston. The fluid circuit is provided with: a switching valve; a first air flow path arranged in the aforementioned first air chamber Between the switching valve and the switching valve; the second air flow path is provided between the second air chamber and the switching valve; the bypass flow path is connecting the intermediate point of the first air flow path and the second air flow The middle point of the path; and the check valve and the pilot check valve are located in the bypass flow path; the check valve allows air to flow from the second air chamber to the first air chamber, and prevents air Circulation from the first air chamber to the second air chamber; the pilot check valve allows air to circulate from the first air chamber to the second air chamber, and prevents air from flowing when the pilot pressure is not applied The flow of the second air chamber to the first air chamber; the first air flow path between the first air chamber and the intermediate point of the first air flow path includes a tank portion. The fluid circuit of the pneumatic cylinder described in the first item of the patent application, wherein the first air flow path between the intermediate point of the first air flow path and the switching valve is provided with a second check valve, The second check valve allows air to flow from the intermediate point of the first air flow path to the switching valve, and prevents air from flowing from the switching valve to the intermediate point of the first air flow path. A pilot flow path is provided between the first air flow path between the return valve and the pilot check valve and the switching valve. When the switching valve is in the first position, the first air flow path is connected to the air supply The source is connected, and the aforementioned second air flow path is connected to the exhaust port; When the switching valve is in the second position, the first air flow path is connected to the exhaust port, and the second air flow path is connected to the air supply source. The fluid circuit of the pneumatic cylinder described in the first item of the patent application, wherein the bypass flow path and the second check valve are provided inside the pneumatic cylinder. The fluid circuit of the pneumatic cylinder described in the scope of patent application 3, wherein the second air flow path between the intermediate point of the second air flow path and the switching valve is provided with a throttle valve, The flow valve is arranged inside the aforementioned pneumatic cylinder. According to the fluid circuit of the pneumatic cylinder described in claim 1, wherein the piston rod connected to the piston penetrates the first air chamber, and the end of the piston rod extends outside through the rod cover.

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