Intermittent air venting fluid circuit

Abstract

An intermittent air discharge fluid circuit (10) includes a main valve (12) provided with a discharge pilot chamber (14), and a pilot valve (18) provided with a supply pilot chamber (20). The main valve is switched between a first position in which the supply pilot chamber is connected to an air supply source (30) and a discharge port (36) is open to the atmosphere, and a second position in which the supply pilot chamber is open to the atmosphere and the discharge port is connected to the air supply source. The pilot valve is switched between a first position in which the discharge pilot chamber is open to the atmosphere, and a second position in which the discharge pilot chamber is connected to the air supply source.

Description

Technical Field

[0001] This invention relates to a fluid circuit for intermittently discharging compressed air or other air. Background Technology

[0002] Previously, it was known that a fluid circuit comprising an air-operated main valve and an air-operated pilot valve was used in a device that intermittently discharges compressed air toward an object such as a workpiece.

[0003] For example, Japanese Patent No. 6289358 discloses an intermittent air discharge device, which includes a main valve that switches the connection and disconnection of an air supply port and an air discharge port, and a pilot valve that can switch between a state of supplying compressed air to the discharge pilot chamber of the main valve and a state of not supplying compressed air to the discharge pilot chamber of the main valve. In this intermittent air discharge device, the compressed air supplied to the air supply port is supplied to both the discharge pilot chamber of the main valve and the air supply stop pilot chamber of the pilot valve.

[0004] In the intermittent air discharge device disclosed in Japanese Patent No. 6289358, compressed air supplied to the air supply port is simultaneously supplied to the pilot chamber of the main valve and the pilot chamber of the pilot valve. Therefore, there is a possibility that the pilot valve may be switched before the main valve is switched. Furthermore, the compressed air supplied to the air supply port is discharged from the discharge port, thus there is a possibility that compressed air with a pressure drop may be supplied to the pilot chambers of both the main valve and the pilot valve. These factors, as the main causes, may lead to instability in the operation of the main valve and the pilot valve. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned problems.

[0006] This invention relates to an intermittent air discharge fluid circuit for intermittently discharging air from the outlet of an air discharge device, comprising: a main valve having a discharge pilot chamber and a pilot valve having a supply pilot chamber. The main valve is switched between a first position where the supply pilot chamber is connected to an air supply source and the outlet is open to the atmosphere, and a second position where the supply pilot chamber is open to the atmosphere and the outlet is connected to the air supply source. The pilot valve is switched between the first position where the discharge pilot chamber is open to the atmosphere and the second position where the discharge pilot chamber is connected to the air supply source.

[0007] According to the fluid circuit for intermittent air venting involved in this invention, the main valve can only be switched after the pilot valve has been switched. Furthermore, even if a pressure drop occurs due to air venting, this pressure drop will not affect the operation of the pilot valve and the main valve. Therefore, stable operation of the main valve and the pilot valve is ensured.

[0008] The aforementioned objectives, features, and advantages should be readily understood from the following description of the embodiments, which are illustrated with reference to the accompanying drawings. Attached Figure Description

[0009] Figure 1 This is a diagram illustrating the fluid circuit for intermittent air discharge according to the first embodiment of the present invention.

[0010] Figure 2 It means in Figure 1 A diagram showing the state of the pilot valve being switched in the fluid circuit for intermittent air discharge.

[0011] Figure 3 It means in Figure 2 A diagram showing the state of the main valve being switched in the intermittent air discharge fluid circuit.

[0012] Figure 4 It means in Figure 3 A diagram showing the state of the pilot valve being switched in the fluid circuit for intermittent air discharge.

[0013] Figure 5 This is a diagram illustrating the fluid circuit for intermittent air discharge according to the second embodiment of the present invention.

[0014] Figure 6 This is a diagram illustrating the fluid circuit for intermittent air discharge according to the third embodiment of the present invention.

[0015] Figure 7 This is a diagram illustrating a specific structural example of the main valve and pilot valve of the present invention. Detailed Implementation

[0016] (First Implementation)

[0017] Reference Figures 1-4 The fluid circuit 10 for intermittent air discharge according to the first embodiment of the present invention will be described.

[0018] like Figure 1 As shown, the intermittent air discharge fluid circuit 10 includes a main valve 12 having a discharge pilot chamber 14 and a pilot valve 18 having an air supply pilot chamber 20. The intermittent air discharge fluid circuit 10 is, for example, an air discharge device (not shown) used to remove foreign matter such as dust adhering to a workpiece by intermittently discharging air toward the workpiece.

[0019] A first cooperating flow path 24 and a second cooperating flow path 26 are configured between the main valve 12 and the pilot valve 18. First to fourth air supply flow paths 28a to 28d are configured between the main valve 12, the pilot valve 18, and the air supply source 30. One end of the first air supply flow path 28a is connected to the air supply source 30, and the other end of the first air supply flow path 28a is connected to the second air supply flow path 28b, the third air supply flow path 28c, and the fourth air supply flow path 28d. The second air supply flow path 28b and the third air supply flow path 28c are connected to the main valve 12. The fourth air supply flow path 28d is connected to the pilot valve 18.

[0020] The third air supply path 28c is a flow path used to supply air to the pilot chamber 20 of the pilot valve 18. The fourth air supply path 28d is a flow path used to supply air to the discharge pilot chamber 14 of the main valve 12. In addition, one end of the first air supply path 28a is always connected to the air supply source 30, but it can also be connected to the air supply source 30 by means of a solenoid valve that switches between connection and disconnection.

[0021] The main valve 12 has first to fifth ports 16a to 16e. The first port 16a is connected to the outlet 36 of the air exhaust device. The second port 16b is connected to the pilot chamber 20 of the pilot valve 18 via a first cooperating flow path 24. The third port 16c is connected to the air supply source 30 via a second air supply flow path 28b and a first air supply flow path 28a. The fourth port 16d is connected to the first exhaust port 32. The fifth port 16e is connected to the air supply source 30 via a third air supply flow path 28c and a first air supply flow path 28a.

[0022] The main valve 12 is switched between a first position and a second position. When the main valve 12 is in the first position, the first port 16a and the fourth port 16d are interconnected, and the second port 16b and the fifth port 16e are interconnected (see reference). Figure 1 and Figure 2 When the main valve 12 is in the second position, the first port 16a and the third port 16c are interconnected, and the second port 16b and the fourth port 16d are interconnected (see reference). Figure 3 and Figure 4 ).

[0023] When air is vented from the exhaust pilot chamber 14, the main valve 12 is switched to the first position; when air is supplied to the exhaust pilot chamber 14, the main valve 12 is switched to the second position. When the main valve 12 is in the first position, the air supply pilot chamber 20 of the pilot valve 18 is connected to the air supply source 30, and the exhaust port 36 is open to the atmosphere through the first exhaust port 32. When the main valve 12 is in the second position, the air supply pilot chamber 20 of the pilot valve 18 is open to the atmosphere through the first exhaust port 32, and the exhaust port 36 is connected to the air supply source 30.

[0024] Pilot valve 18 has first to third ports 22a to 22c. First port 22a is connected to the discharge pilot chamber 14 of main valve 12 via second cooperating flow path 26. Second port 22b is connected to air supply source 30 via fourth supply flow path 28d and first supply flow path 28a. Third port 22c is connected to second exhaust port 34.

[0025] Pilot valve 18 is switched between a first position and a second position. When pilot valve 18 is in the first position, the first port 22a and the third port 22c are connected, and the connection between the first port 22a and the second port 22b is cut off (see reference). Figure 1 and Figure 4 When the pilot valve 18 is in the second position, the first port 22a and the second port 22b are connected, and the connection between the first port 22a and the third port 22c is cut off (see reference). Figure 2 and Figure 3 ).

[0026] When air is vented from the air supply pilot chamber 20, pilot valve 18 is switched to the first position; when air is supplied to the air supply pilot chamber 20, pilot valve 18 is switched to the second position. When pilot valve 18 is in the first position, the discharge pilot chamber 14 of the main valve 12 is open to the atmosphere through the second exhaust port 34. When pilot valve 18 is in the second position, the discharge pilot chamber 14 of the main valve 12 is connected to the air supply source 30.

[0027] Furthermore, reference numeral 70 indicates the air chamber that applies air pressure in opposition to the discharge pilot chamber 14, and reference numeral 82 indicates the pilot air chamber that applies air pressure in opposition to the supply pilot chamber 20. Air is supplied to the air chamber 70 and the pilot air chamber 82 from the air supply source 30 regardless of the switching position of the main valve 12 and the pilot valve 18.

[0028] Next, the operation of the fluid circuit 10 for intermittent air discharge will be explained. For example... Figure 1 As shown, the initial state is defined by the main valve 12 being in the first position and the pilot valve 18 being in the first position. It is assumed that one end of the first air supply path 28a is always connected to the air supply source 30. In the initial state, the air supply source 30 is stopped.

[0029] When the air supply source 30 starts operating, air from the air supply source 30 is supplied to the pilot chamber 20 of the pilot valve 18 via the first supply flow path 28a, the third supply flow path 28c, the main valve 12, and the first cooperating flow path 24. Thus, as... Figure 2As shown, the pilot valve 18 switches from the first position to the second position. Furthermore, when one end of the first air supply path 28a is connected to the air supply source 30 via a solenoid valve, assuming that the air supply source 30 is operating, the above-mentioned "the air supply source 30 starts operating" can also be referred to as "the solenoid valve is switched to the open position and the first air supply path 28a is connected to the air supply source 30".

[0030] When the pilot valve 18 is switched to the second position, air from the air supply source 30 is supplied to the discharge pilot chamber 14 of the main valve 12 via the first supply flow path 28a, the fourth supply flow path 28d, the pilot valve 18, and the second cooperating flow path 26. Thus, as Figure 3 As shown, the main valve 12 switches from the first position to the second position.

[0031] When the main valve 12 is switched to the second position, air from the air supply source 30 is discharged from the outlet 36 via the first supply flow path 28a, the second supply flow path 28b, and the main valve 12. Simultaneously, air from the pilot chamber 20 of the pilot valve 18 is discharged from the first exhaust port 32 via the first cooperating flow path 24 and the main valve 12. Thus, as... Figure 4 As shown, the pilot valve 18 switches from the second position to the first position.

[0032] When pilot valve 18 is switched to the first position, air from the main valve 12's discharge pilot chamber 14 is exhausted from the second exhaust port 34 via the second cooperating flow path 26 and pilot valve 18. Thus, as... Figure 1 As shown, the main valve 12 switches from the second position to the first position. During the operation of the air supply source 30, the above operation is repeated periodically, and air is intermittently discharged from the outlet 36. Furthermore, when one end of the first air supply path 28a is connected to the air supply source 30 by means of a solenoid valve, the above-mentioned "operation period of the air supply source 30" can also be referred to as "the period when the solenoid valve is in the open position".

[0033] According to the intermittent air discharge fluid circuit 10 of this embodiment, the main valve 12, which is in the first position, can only switch to the second position after the pilot valve 18 switches from the first position to the second position. Furthermore, the main valve 12, which is in the second position, can only switch to the first position after the pilot valve 18 switches from the second position to the first position. This ensures stable operation of the main valve 12.

[0034] Furthermore, after the main valve 12 is switched to the first position, the air from the air supply source 30, when supplied to the air supply pilot chamber 20 of the pilot valve 18 and the discharge pilot chamber 14 of the main valve 12, is not discharged from the discharge port 36. Therefore, the air supplied to the air supply pilot chamber 20 of the pilot valve 18 and the discharge pilot chamber 14 of the main valve 12 will not experience a pressure drop.

[0035] On the other hand, after the main valve 12 switches to the second position, air from the air supply source 30 is discharged from the outlet 36 and also supplied to the pilot air chamber 82 of the pilot valve 18 and the air chamber 70 of the main valve 12. At this time, air with a pressure drop may be supplied to the pilot air chamber 82 and the air chamber 70, but it can be considered that this pressure drop has minimal impact on subsequent switching (switching from the second position to the first position). This is because when the air in the pilot chamber 20 for supplying air to the pilot valve 18 and the pilot chamber 14 for discharging air to the main valve 12 is exhausted and becomes open to the atmosphere, there is almost no residual pressure that would force the pilot valve 18 and the main valve 12 to the second position. Since there is almost no residual pressure, as long as air is supplied to the pilot air chamber 82 and the air chamber 70, the main valve 12 and the pilot valve 18 can reliably switch to the first position. Based on the above, stable operation of the main valve 12 and the pilot valve 18 can be ensured.

[0036] Furthermore, in the above embodiment, air from the air supply source 30 is used to switch the main valve 12 and the pilot valve 18 from the second position to the first position. Alternatively, a force-applying component such as a spring or a combination of air and spring can be used. In this case, the effect of pressure drop can be further eliminated.

[0037] (Second Implementation)

[0038] Next, refer to Figure 5 The intermittent air discharge fluid circuit 40 according to the second embodiment of the present invention will be described. The intermittent air discharge fluid circuit 40 according to the second embodiment differs from the intermittent air discharge fluid circuit 10 according to the first embodiment in that it includes a circuit for adjusting the operating frequency of the main valve 12 and the pilot valve 18. Furthermore, the same reference numerals are used for components that are the same as or equivalent to those in the intermittent air discharge fluid circuit 10 according to the first embodiment, and detailed descriptions are omitted.

[0039] The first variable throttle valve 42 is disposed midway in the first cooperative flow path 24, and the first check valve 44 is disposed in the flow path that bypasses the first variable throttle valve 42. That is, the first check valve 44 and the first variable throttle valve 42 are disposed side by side. The first check valve 44 allows air to flow from the air supply pilot chamber 20 of the pilot valve 18 to the second port 16b of the main valve 12, and prevents air from flowing from the second port 16b of the main valve 12 to the air supply pilot chamber 20 of the pilot valve 18. For this reason, the flow rate of air supplied from the air supply source 30 to the air supply pilot chamber 20 of the pilot valve 18 is limited accordingly with respect to the flow path area set by the first variable throttle valve 42.

[0040] The second variable throttle valve 46 is positioned midway through the second cooperative flow path 26, and the second check valve 48 is positioned in the flow path that bypasses the second variable throttle valve 46. That is, the second check valve 48 and the second variable throttle valve 46 are arranged side-by-side. The second check valve 48 allows air to flow from the first port 22a of the pilot valve 18 to the discharge pilot chamber 14 of the main valve 12, and prevents air from flowing from the discharge pilot chamber 14 of the main valve 12 back to the first port 22a of the pilot valve 18. Therefore, the flow rate of air discharged from the discharge pilot chamber 14 of the main valve 12 to the second exhaust port 34 is correspondingly limited by the flow path area set by the second variable throttle valve 46.

[0041] The smaller the air flow rate supplied to the air supply pilot chamber 20, the slower the pressure rise rate in the air supply pilot chamber 20, and the longer the time (T1) from when the main valve 12 switches to the first position to when the pilot valve 18 switches to the second position. The smaller the air flow rate discharged from the discharge pilot chamber 14, the longer the time (T2) from when the pilot valve 18 switches to the first position to when the main valve 12 switches to the first position.

[0042] The longer T1 and T2 are, the less frequently the main valve 12 and pilot valve 18 operate. Since T1 includes the time period during which air is not discharged from the outlet 36, the longer T1 is, the smaller the flow rate of air discharged from the outlet 36. On the other hand, since T2 includes the time period during which air is discharged from the outlet 36, the longer T2 is, the larger the flow rate of air discharged from the outlet 36. To increase the flow rate of air discharged from the outlet 36, it is only necessary to shorten T1 and lengthen T2. ​​In other words, to increase the flow rate of air discharged from the outlet 36, it is only necessary to increase the flow path area set by the first variable throttle valve 42 and decrease the flow path area set by the second variable throttle valve 46.

[0043] According to the intermittent air discharge fluid circuit 40 of this embodiment, the operating frequency of the main valve 12 and the pilot valve 18 can be adjusted, and the flow rate of the air discharged from the discharge port 36 can be adjusted.

[0044] The specific structures of the main valve 12 and the pilot valve 18 are as follows: Figure 7 As shown. The main valve 12 includes a body 60, a sleeve 62, and a slide valve 64. The pilot valve 18 includes a pilot body 74, a pilot sleeve 76, and a pilot slide valve 78.

[0045] The main body 60 has first to fifth ports 16a to 16e. A sleeve 62 is fixed inside the main body 60. A slide valve 64 slides inside the sleeve 62, thereby changing the connection relationship of the first to fifth ports 16a to 16e. Figure 7As shown, when the slide valve 64 is in the left moving position, the first port 16a and the fourth port 16d are interconnected, and the second port 16b and the fifth port 16e are interconnected. That is, Figure 7 This indicates that the main valve 12 is in the first position. When the slide valve 64 moves to the right, the first port 16a and the third port 16c are connected, and the second port 16b and the fourth port 16d are connected. That is, the main valve 12 switches to the second position.

[0046] The first piston 66 abuts against the left end of the slide valve 64. A discharge pilot chamber 14 is formed to the left of the first piston 66. The second piston 68 abuts against the right end of the slide valve 64. An air chamber 70 communicating with the third port 16c is formed to the right of the second piston 68. A spring 72 is disposed in the air chamber 70 to apply a force to the second piston 68 to the left.

[0047] The pilot body 74 has first to third ports 22a to 22c. A pilot sleeve 76 is fixed inside the pilot body 74. The connection relationship of the first to third ports 22a to 22c is changed by the sliding of a pilot valve 78 within the pilot sleeve 76. Figure 7 As shown, when the pilot slide valve 78 is in the right-hand moving position, the first port 22a and the third port 22c are connected to each other. That is, Figure 7 This indicates that the pilot valve 18 is in the first position. When the pilot slide valve 78 moves to the left, the first port 22a and the second port 22b are connected, and the pilot valve 18 switches to the second position.

[0048] The pilot piston 80 abuts against the right end of the pilot slide valve 78. A pilot chamber 20 for air supply is formed to the right of the pilot piston 80. A pilot air chamber 82 communicating with the second port 22b is formed to the left of the pilot slide valve 78. A pilot spring 84 is disposed in the pilot air chamber 82, applying force to the right of the pilot slide valve 78. Furthermore, the spring 72 and the pilot spring 84 are not essential components.

[0049] Figure 7 The structural example can also be applied to the intermittent air discharge fluid circuit 10 according to the first embodiment and the intermittent air discharge fluid circuit 50 according to the third embodiment described later. Furthermore, in Figure 7 In the structural example, the second port 22b of the pilot valve 18 is connected to the air supply source 30 via the fourth air supply path 28d and the third air supply path 28c.

[0050] (Third Implementation)

[0051] Next, refer to Figure 6The intermittent air discharge fluid circuit 50 according to the third embodiment of the present invention will be described. The intermittent air discharge fluid circuit 50 according to the third embodiment includes a first air supply source 54 connected to the main valve 12, and a second air supply source 56 connected to the main valve 12 and the pilot valve 18, which differs from the intermittent air discharge fluid circuit 40 according to the second embodiment. Furthermore, the intermittent air discharge fluid circuit 50 according to the third embodiment includes an external pilot valve 58, which also differs from the intermittent air discharge fluid circuit 40 according to the second embodiment. In addition, the same reference numerals are used for components that are identical or equivalent to those in the intermittent air discharge fluid circuit 40 according to the second embodiment.

[0052] A first cooperating flow path 24 and a second cooperating flow path 26 are configured between the main valve 12 and the pilot valve 18. A first air supply flow path 52a is configured between the main valve 12 and the first air supply source 54. The first air supply flow path 52a is always connected to the first air supply source 54. A second air supply flow path 52b, a third air supply flow path 52c, and a fourth air supply flow path 52d are configured between the main valve 12, the pilot valve 18, and the second air supply source 56. One end of the second air supply flow path 52b is connected to the second air supply source 56, and the other end of the second air supply flow path 52b is connected to the third air supply flow path 52c and the fourth air supply flow path 52d. The third air supply flow path 52c is connected to the main valve 12. The fourth air supply flow path 52d is connected to the pilot valve 18. An external pilot valve 58 is configured in the middle of the second air supply flow path 52b.

[0053] The main valve 12 has first to fifth ports 16a to 16e. The first port 16a is connected to the outlet 36. The second port 16b is connected to the pilot chamber 20 of the pilot valve 18 via a first cooperating flow path 24. The third port 16c is connected to the first air supply source 54 via a first air supply flow path 52a. The fourth port 16d is connected to the first exhaust port 32. The fifth port 16e is connected to the second air supply source 56 via the third air supply flow path 52c and the second air supply flow path 52b.

[0054] Pilot valve 18 has first to third ports 22a to 22c. First port 22a is connected to the discharge pilot chamber 14 of main valve 12 via second cooperating flow path 26. Second port 22b is connected to second air supply source 56 via fourth air supply path 52d and second air supply path 52b. Third port 22c is connected to second exhaust port 34.

[0055] The main valve 12 is switched between a first position and a second position. When the main valve 12 is in the first position, the first port 16a and the fourth port 16d are interconnected, and the second port 16b and the fifth port 16e are interconnected. When the main valve 12 is in the second position, the first port 16a and the third port 16c are interconnected, and the second port 16b and the fourth port 16d are interconnected.

[0056] When air is exhausted from the exhaust pilot chamber 14, the main valve 12 switches to the first position; when air is supplied to the exhaust pilot chamber 14, the main valve 12 switches to the second position. When the main valve 12 is in the first position, the air supply pilot chamber 20 of the pilot valve 18 is connected to the second air supply source 56 via an external pilot valve 58, and the exhaust port 36 is open to the atmosphere through the first exhaust port 32. When the main valve 12 is in the second position, the air supply pilot chamber 20 of the pilot valve 18 is open to the atmosphere through the first exhaust port 32, and the exhaust port 36 is connected to the first air supply source 54.

[0057] Pilot valve 18 is switched between a first position and a second position. When pilot valve 18 is in the first position, the first port 22a and the third port 22c are connected, and the connection between the first port 22a and the second port 22b is cut off. When pilot valve 18 is in the second position, the first port 22a and the second port 22b are connected, and the connection between the first port 22a and the third port 22c is cut off.

[0058] An external pilot valve 58 is configured as a two-port valve, switching between a closed position and an open position. When the external pilot valve 58 is in the open position, the second air supply source 56 is connected to the fifth port 16e of the main valve 12 and the second port 22b of the pilot valve 18. When the external pilot valve 58 is in the closed position, the connection between the second air supply source 56 and the fifth port 16e of the main valve 12 is cut off, and the connection between the second air supply source 56 and the second port 22b of the pilot valve 18 is also cut off. The external pilot valve 58 controls the start and stop of the air discharge from the outlet 36.

[0059] When air is vented from the air supply pilot chamber 20, pilot valve 18 switches to the first position. When air is supplied to the air supply pilot chamber 20, pilot valve 18 switches to the second position. When pilot valve 18 is in the first position, the discharge pilot chamber 14 of the main valve 12 is open to the atmosphere through the second exhaust port 34. When pilot valve 18 is in the second position and external pilot valve 58 is in the open position, the discharge pilot chamber 14 of the main valve 12 is connected to the second air supply source 56.

[0060] Next, the operation of the intermittent air discharge fluid circuit 50 will be explained. In the initial state, the first air supply source 54 and the second air supply source 56 are operating, and the external pilot valve 58 is in the closed position. Furthermore, the main valve 12 is in the first position, and the pilot valve 18 is in the first position. Air is not discharged from the discharge port 36.

[0061] When the external pilot valve 58 is opened, air from the second air supply source 56 is supplied to the pilot chamber 20 of the pilot valve 18 via the second air supply path 52b, the third air supply path 52c, the main valve 12, and the first cooperating flow path 24. As a result, the pilot valve 18 switches from the first position to the second position.

[0062] When the pilot valve 18 is switched to the second position, air from the second air supply source 56 is supplied to the discharge pilot chamber 14 of the main valve 12 via the second air supply path 52b, the fourth air supply path 52d, the pilot valve 18, and the second cooperating flow path 26. As a result, the main valve 12 switches from the first position to the second position.

[0063] When the main valve 12 is switched to the second position, air from the first air supply source 54 is discharged from the outlet 36 via the first supply flow path 52a and the main valve 12. At the same time, air from the pilot chamber 20 of the pilot valve 18 is discharged from the first exhaust port 32 via the first cooperating flow path 24 and the main valve 12. Thus, the pilot valve 18 switches from the second position to the first position.

[0064] When pilot valve 18 is switched to the first position, air from the main valve 12's discharge pilot chamber 14 is exhausted from the second exhaust port 34 via the second cooperating flow path 26 and pilot valve 18. Thus, the main valve 12 switches from the second position to the first position. During the period when the external pilot valve 58 is in the open position, the above action is repeated periodically, intermittently venting air from the discharge port 36.

[0065] When the external pilot valve 58 switches to the closed position, the air supply to the second port 22b of the pilot valve 18 is stopped. Therefore, when the pilot valve 18 is in the second position, the air supply to the discharge pilot chamber 14 of the main valve 12 is stopped. When the air supply to the discharge pilot chamber 14 of the main valve 12 stops, and the main valve 12 is in the second position without air being discharged from the discharge port 36, the air in the air supply pilot chamber 20 of the pilot valve 18 is vented, and the pilot valve 18 switches to the first position.

[0066] When the pilot valve 18 is switched to the first position, the air in the discharge pilot chamber 14 of the main valve 12 is rapidly vented, the main valve 12 switches to the first position, and stops venting air from the discharge port 36. Then, since no air is supplied to the discharge pilot chamber 14 of the main valve 12, the state of not venting air from the discharge port 36 can be reliably maintained.

[0067] According to the intermittent air discharge fluid circuit 50 of this embodiment, the flow rate of air discharged from the discharge port 36 can be determined based on the capacity of the first air supply source 54. Furthermore, the flow rate of air supplied to the discharge pilot chamber 14 of the main valve 12 and the flow rate of air supplied to the air supply pilot chamber 20 of the pilot valve 18 can be determined based on the capacity of the second air supply source 56. Therefore, this is useful when a large flow rate of air is discharged from the discharge port 36.

[0068] This invention is not limited to the above-described embodiments; various structures can be adopted as long as they do not depart from the spirit of this invention.

Claims

1. A fluid circuit (10, 40, 50) for intermittent air discharge, used to intermittently discharge air from the outlet (36) of an air discharge device toward a workpiece, characterized in that, include: A main valve (12) having a discharge pilot chamber (14) and a pilot valve (18) having a gas supply pilot chamber (20) are provided. The main valve is switched between a first position where the gas supply pilot chamber is connected to an air supply source (30, 56) and the discharge outlet is open to the atmosphere and a second position where the gas supply pilot chamber is open to the atmosphere and the discharge outlet is connected to an air supply source (30, 54). The pilot valve is switched between the first position where the discharge pilot chamber is open to the atmosphere and the second position where the discharge pilot chamber is connected to an air supply source (30, 56). The discharge outlet is connected to a first air supply source (54), and the gas supply pilot chamber and the discharge pilot chamber are connected to a second air supply source (56).

2. The fluid circuit for intermittent air discharge as described in claim 1, wherein, The air supply pilot chamber and the exhaust pilot chamber are connected to the second air supply source via an external pilot valve (58).

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