Air control circuit with safety function

Abstract

This air control circuit equipped with a safety feature is composed of only an air circuit.　The circuit comprises a main air line (4) that controls an air device (3) by turning two external pilot–type solenoid valves (5a, 5b) on and off simultaneously, a pilot air line (6) that supplies pilot air to the solenoid valves (5a, 5b), and a pilot control line (7) that switches the pilot air line (6) between a supplying state and a discharging state, wherein when one of the two solenoid valves (5a, 5b) malfunctions and does not switch to the off position, the air device (3) is reset by discharging the air in the air device (3) through the other solenoid valve that switched to the off position, and reactivation of the two solenoid valves (5a, 5b) is prevented by switching the pilot air line (6) to the discharging state via the pilot control line (7).

Description

[Technical Field]

[0001] The present invention relates to an air control circuit with a safety function for safely controlling air equipment such as an air cylinder. [Background technology]

[0002] An air control circuit equipped with a safety function for safely controlling pneumatic equipment such as an air cylinder is known, for example as shown in Figure 11. This known air control circuit is configured by connecting two internal pilot-operated, spring-return type three-port solenoid valves 43, 44 in series in an air line 42 connecting an air source 40 and an air cylinder 41, so that even if one of the solenoid valves 43 or 44 malfunctions and stops functioning properly while the air cylinder 41 is in operation, the other solenoid valve 44 or 43 can be turned off to ensure that any remaining air in the air cylinder 41 is exhausted.

[0003] However, in the known air control circuit, a failure of one of the solenoid valves 43 or 44 must be detected by an electric signal, and this electric signal must be used to control the other solenoid valve by using a control device 45 such as a sequencer to turn off the other solenoid valve. Therefore, it is necessary to use solenoid valves equipped with limit switches 46 that detect the operating positions of the solenoid valves 43, 44 and output an electric signal, and at the same time, the sequencer and its control program are also required, which not only increases equipment costs but also poses the problem of having to secure engineers who are familiar with safety functions and sequencer programs. Summary of the Invention [Problem to be solved by the invention]

[0004] The technical object of the present invention is to construct an air control circuit equipped with a safety function for safely controlling air equipment using only an air circuit, without using a solenoid valve with a limit switch, a sequencer, etc. [Means for solving the problem]

[0005] In order to solve the above problems, the air control circuit of the present invention has a main air line in which two external pilot type solenoid valves are connected in series, a pilot air line that supplies pilot air to the two solenoid valves, and a pilot control line that switches the pilot air line between a supply state in which pilot air is supplied to the two solenoid valves and an exhaust state in which pilot air is exhausted from the two solenoid valves. The two solenoid valves in the main air line are two-position valves having a first position when off and a second position when on, and when both the two solenoid valves are in the first position, they shut off the air source from the air equipment and exhaust air from the air equipment through one of the solenoid valves, when both the two solenoid valves are in the second position, they connect the air source to the air equipment and supply air from the air source to the air equipment, and when one of the two solenoid valves is in the first position and the other is in the second position, they are connected to shut off the air source from the air equipment and exhaust air from the air equipment through the solenoid valve in the first position. An air-operated valve is connected to the pilot air line and has a first position that places the pilot air line in the supply state and a second position that places the pilot air line in the exhaust state. Furthermore, the pilot control line is configured to be connected to and disconnected from the air source by the two solenoid valves, and when the two solenoid valves are both in the first position and both in the second position, the pilot control line is disconnected from the air source, thereby holding the air operated valve at the first position where the pilot air line is in a supply state, and when one of the two solenoid valves is in the first position and the other is in the second position, the pilot control line is connected to the air source via the two solenoid valves, and the air operated valve is switched to the second position where the pilot air line is in an exhaust state by control air supplied from the air source.

[0006] In the present invention, it is desirable that the air-operated valve has a detent mechanism that holds the air-operated valve in the second position, and a release button that releases the hold of the detent mechanism.

[0007] The air control circuit of the present invention may be configured such that a pilot-operated check valve, a manual relief valve, and the air-operated valve are connected to the pilot control line, and the pilot-operated check valve allows the control air to flow in a forward direction from the air source toward the air-operated valve through the pilot control line when pilot air from the pilot air line acts on the pilot check valve, and prevents the control air from flowing in the reverse direction when the pilot air does not act on the pilot check valve, and the manual relief valve manually switches the pilot control line from a conductive state in which the control air can flow to an open state in which the control air is discharged to the outside.

[0008] In addition, the air control circuit of the present invention may be configured such that an air tank is connected to the pilot control line, and the air tank stores the control air supplied from the air source and supplies it to the air operated valve.

[0009] Furthermore, in the air control circuit of the present invention, the two solenoid valves may be five-port valves having one input port, first and second output ports, and first and second exhaust ports, and the two solenoid valves may comprise a first solenoid valve connected to the air source side of the main air line and a second solenoid valve connected to the air equipment side of the main air line, the input port of the first solenoid valve being connected to the air source, the first output port of the first solenoid valve being connected to the input port of the second solenoid valve, the second output port of the first solenoid valve being connected to the second exhaust port of the second solenoid valve, the first exhaust port and the second exhaust port of the first solenoid valve being open to the outside, the first output port of the second solenoid valve being connected to the air equipment, the second output port of the second solenoid valve being connected to the pilot control line, and the first exhaust port of the second solenoid valve being open to the outside.

[0010] In the air control circuit of the present invention, a delay mechanism for delaying the start of the air device may be connected to the main air line. In this case, it is desirable that the delay mechanism be composed of a switching valve operated by air and a throttle valve that limits the flow rate of air, and when both of the two solenoid valves are turned on and the air source and the pneumatic equipment are connected, air at the limited flow rate is circulated through the main airline through the throttle valve, and when a portion of the air output from the main airline to the pneumatic equipment is fed back to the switching valve, the switching valve switches to allow air from the air source to circulate in a free flow state through the main airline. [Effects of the Invention]

[0011] According to the present invention, an air control circuit equipped with a safety function is constructed using only an air circuit, without using a solenoid valve with a limit switch, a sequencer, etc., so the construction is very simple, the equipment cost is low, and there is no need to secure engineers who are familiar with the safety function and sequencer programs. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a circuit diagram showing a first embodiment of an air control circuit according to the present invention. [Figure 2] 5A to 5C are circuit diagrams illustrating different operating states of the air control circuit. [Figure 3] FIG. 6 is a circuit diagram showing yet another operating state of the air control circuit. [Figure 4] FIG. 6 is a circuit diagram showing yet another operating state of the air control circuit. [Figure 5] FIG. 10 is a diagram showing the state when the manual relief valve is operated. [Figure 6] FIG. 10 is a connection diagram showing another example of a manual relief valve. [Figure 7] FIG. 4 is a circuit diagram showing a second embodiment of an air control circuit according to the present invention. [Figure 8] FIG. 4 is a circuit diagram showing a third embodiment of an air control circuit according to the present invention. [Figure 9]9A to 9C are diagrams illustrating different operating states of the delay mechanism in FIG. 8. [Figure 10] FIG. 10 is a connection diagram showing a different example of a delay mechanism. [Figure 11] FIG. 1 is a circuit diagram showing a known air control circuit. DETAILED DESCRIPTION OF THE INVENTION

[0013] 1 to 5 show a first embodiment of an air control circuit with a safety function according to the present invention. This air control circuit 1A connects an air source 2 to an air device 3 and controls the air device 3 by supplying air from the air source 2 to the air device 3 and exhausting the air from the air device 3 to the outside. The air control circuit 1A includes a main air line 4 to which two external pilot type solenoid valves 5a, 5b are connected in series, a pilot air line 6 that supplies pilot air to the two solenoid valves 5a, 5b, and a pilot control line 7 that switches the pilot air line 6 between a supply state in which pilot air is supplied to the two solenoid valves 5a, 5b and an exhaust state in which pilot air is exhausted from the two solenoid valves 5a, 5b.

[0014] In this embodiment, the air device 3 is an air cylinder, and the air cylinder 3 is a single-acting air cylinder in which a piston 3a and a rod 3b are driven to reciprocate by air supplied to a pressure chamber 3c and a return spring 3d.

[0015] The two solenoid valves 5a, 5b have the same configuration, and are configured so that they can be switched between a first position 12 when off and a second position 13 when on by pilot air supplied and discharged by turning on and off a single solenoid 10, and by a return spring 11. Therefore, the solenoid valves 5a, 5b can be said to be single solenoid, spring-return type, two-position valves. The solenoid valves 5a and 5b are five-port valves and have one input port 14, two output ports, i.e., a first output port 15a and a second output port 15b, and two exhaust ports, i.e., a first exhaust port 16a and a second exhaust port 16b.

[0016] Of the two solenoid valves 5a, 5b, one solenoid valve 5a is a first solenoid valve 5a connected to the air source 2 side of the main air line 4, and the other solenoid valve 5b is a second solenoid valve 5b connected to the air cylinder 3 side of the main air line 4. An input port 14 of the first solenoid valve 5a is connected to the air source 2 via an input line 4a, a first output port 15a of the first solenoid valve 5a is connected to an input port 14 of the second solenoid valve 5b via a first relay line 4b, a second output port 15b of the first solenoid valve 5a is connected to a second exhaust port 16b of the second solenoid valve 5b via a second relay line 4c, and the first exhaust port 16a and second exhaust port 16b of the first solenoid valve 5a are each open to the outside via a silencer 17. In addition, a first output port 15a of the second solenoid valve 5b is connected to the pressure chamber 3c of the air cylinder 3 through an output line 4d, a second output port 15b of the second solenoid valve 5b is connected to one end of the pilot control line 7, and a first exhaust port 16a of the second solenoid valve 5b is opened to the outside via a silencer 17.

[0017] The two solenoid valves 5a and 5b connected to the main air line 4 are always simultaneously turned on and off by a control device (not shown) to control the air equipment, and their operation is as follows.

[0018] First, as shown in FIG. 1, when both solenoid valves 5a, 5b are off and in the first position 12, the air source 2 and the air cylinder 3 are shut off from each other, and air in the pressure chamber 3c of the air cylinder 3 is exhausted to the outside through one solenoid valve, 5b. That is, the input line 4a from the air source 2 is connected to the second relay line 4c by the first solenoid valve 5a, but the second relay line 4c is shut off by the second solenoid valve 5b. In addition, the output line 4d connecting the first output port 15a of the second solenoid valve 5b and the air cylinder 3 is opened to the outside through the first exhaust port 16a of the second solenoid valve 5b, exhausting air from the air cylinder 3. As a result, the piston 3a and rod 3b of the air cylinder 3 are retracted to their initial positions by the return spring 3d.

[0019] At this time, the pilot control line 7 is open to the outside from the second output port 15b and input port 14 of the second solenoid valve 5b through the first relay line 4b, the first output port 15a and first exhaust port 16a of the first solenoid valve 5a.

[0020] 2, when both solenoid valves 5a, 5b are turned on and switched to the second position 13, the air source 2 and the air cylinder 3 are connected to each other. That is, the input line 4a from the air source 2, the first relay line 4b, and the output line 4d are sequentially connected via the first solenoid valve 5a and the second solenoid valve 5b, and air is supplied from the air source 2 to the pressure chamber 3c of the air cylinder 3. As a result, the piston 3a and rod 3b of the air cylinder 3 move forward toward their operating positions.

[0021] At this time, the pilot control line 7 is open to the outside from the second output port 15b and second exhaust port 16b of the second solenoid valve 5b through the second relay line 4c and the second output port 15b and second exhaust port 16b of the first solenoid valve 5a.

[0022] Subsequently, when the two solenoid valves 5a, 5b are simultaneously turned off to return the air control circuit 1A and the air cylinder 3 to the state shown in FIG. 1, if one of the solenoid valves fails and does not switch to the first position 12, the air source 2 and the air device 3 are cut off, and the air in the pressure chamber 3c of the air cylinder 3 is exhausted through the solenoid valve 5a or 5b that has returned to the first position 12, as will be described below.

[0023] 3, if the first solenoid valve 5a fails and remains in the second position 13, and the second solenoid valve 5b operates normally and returns to the first position 12, the input line 4a from the air source 2 is connected to the pilot control line 7 from the first solenoid valve 5a through the first relay line 4b and the second solenoid valve 5b, thereby supplying control air to the pilot control line 7. Meanwhile, the output line 4d leading to the air cylinder 3 is cut off from the air source 2 and is opened to the outside through the first output port 15a and the first exhaust port 16a of the second solenoid valve 5b, so that the air in the air cylinder 3 is exhausted through the second solenoid valve 5b, and the air cylinder 3 returns to its initial position.

[0024] 4, if the first solenoid valve 5a operates normally and returns to the first position 12, and the second solenoid valve 5b fails and remains in the second position 13, the input line 4a from the air source 2 is connected to the pilot control line 7 from the first solenoid valve 5a through the second relay line 4c and the second solenoid valve 5b, and control air is supplied to the pilot control line 7. On the other hand, the output line 4d is cut off from the air source 2 and is opened to the outside from the second solenoid valve 5b through the first relay line 4b, the first output port 15a of the first solenoid valve 5a, and the first exhaust port 16a, so that the air in the air cylinder 3 is exhausted through the first solenoid valve 5a, and the air cylinder 3 returns to its initial position.

[0025] Returning to FIG. 1, the pilot air line 6 branches off from the main air line 4 at a position between the air source 2 and the first solenoid valve 5a, and is connected to pilot ports 21 of the first solenoid valve 5a and the second solenoid valve 5b via air control valves 20 connected to the pilot air line 6.

[0026] In the following explanation, the input side of the air control valve 20 (the side connected to the air source 2) will be referred to as the primary side, and the output side (the side connected to the solenoid valves 5a and 5b) will be referred to as the secondary side. Therefore, of the pilot air line 6, the section from the air source 2 to the air control valve 20 is the primary side line 6a, and the section from the air control valve 20 to the two solenoid valves 5a and 5b is the secondary side line 6b.

[0027] The air operated valve 20 is a three-port valve that can be switched between two positions by the action of control air supplied through the pilot control line 7 and a return spring 22. As shown in Figures 1 and 2, when the pilot control line 7 is disconnected from the air source 2 and the control air is not acting, the air operated valve 20 is switched to a first position 20a by the return spring 22, thereby maintaining the pilot air line 6 in a supply state in which the primary side line 6a and secondary side line 6b are connected, and as shown in Figures 3 and 4, when the pilot control line 7 is connected to the air source 2 and the control air acts, the air operated valve 20 is switched to a second position 20b by the control air, thereby blocking the primary side line 6a and secondary side line 6b of the pilot air line 6 and opening the secondary side line 6b to the outside and establishing an exhaust state.

[0028] A pilot check valve 23, a manual relief valve 24, and an air tank 25 are connected in series to the pilot control line 7, in that order, from the second solenoid valve 5b side toward the air operated valve 20 side, and an indicator light 26 is connected to an indicator line 7a that branches off from a position between the manual relief valve 24 and the air tank 25, to indicate that control air is being supplied to the pilot control line 7.

[0029] The pilot type check valve 23 allows the pilot control line 7 to flow in both directions when pilot air is applied from the pilot air line 6, and allows the pilot control line 7 to flow in only one direction when the pilot air is not applied. That is, when the pilot air is applied, the pilot type check valve 23 allows the control air to flow in the forward direction from the air source 2 to the air operated valve 20, and the control air to flow in the reverse direction from the air operated valve 20 side to the air source 2 side, within the pilot control line 7, and when the pilot air is not applied, the pilot type check valve 23 allows only the forward flow of the control air and prevents the reverse flow.

[0030] The manual relief valve 24 is a three-port valve that can be switched between two positions by an operating lever 27 and a return spring 28. When the manual relief valve 24 is switched to a first position 24a by the return spring 28 as shown in Fig. 1, it holds the pilot control line 7 in a conductive state that allows the control air to flow, and when it is switched to a second position 24b in Fig. 5 by the operating lever 27, it holds the pilot control line 7 in an open state that discharges the control air to the outside, and when the operating lever 27 is released, it returns to the first position 24a by the return spring 28.

[0031] The air tank 25 stores the control air supplied from the air source 2 and then supplies it from the air tank 25 to the air control valve 20, thereby stabilizing the supply of the control air.

[0032] Next, the overall operation of the air control circuit 1A will be described. FIG. 1 shows a state in which the first solenoid valve 5 a and the second solenoid valve 5 b are both off and in the first position 12 , and the main air line 4 cuts off communication between the air source 2 and the air cylinder 3 . At this time, the air in the pressure chamber 3c of the air cylinder 3 is exhausted to the outside from the output line 4d through the second solenoid valve 5b, so the air cylinder 3 is in its initial position with the rod 3b retracted. Also, because control air from the air source 2 is not supplied to the pilot control line 7, the air operation valve 20 is in its first position 20a, maintaining the pilot air line 6 in a supply state. Therefore, pilot air from the air source 2 is supplied to the first solenoid valve 5a and the second solenoid valve 5b through the pilot air line 6. Furthermore, the pilot check valve 23 allows the pilot control line 7 to flow in both directions by the action of pilot air.

[0033] 2, when the first solenoid valve 5a and the second solenoid valve 5b are simultaneously turned on and switched to the second position 13, the air source 2 and the pressure chamber 3c of the air cylinder 3 are communicated through the input line 4a, the first solenoid valve 5a, the first relay line 4b, the second solenoid valve 5b, and the output line 4d. As a result, air is supplied from the air source 2 to the pressure chamber 3c, causing the rod 3b of the air cylinder 3 to move forward toward the working position. At this time, the pilot control line 7 remains disconnected from the air source 2 .

[0034] When the work process using the air cylinder 3 is completed, the first solenoid valve 5a and the second solenoid valve 5b are simultaneously turned off, and the air control circuit 1A returns to the operating state shown in FIG. 1, so that the air cylinder 3 also returns to the initial position.

[0035] However, if one of the two solenoid valves 5a, 5b fails and does not return to the first position 12, as will be explained below, the air in the air cylinder 3 is exhausted through the restored solenoid valve 5a or 5b, thereby returning the air cylinder 3 to its initial position, and at the same time, the pilot air from the first solenoid valve 5a and the second solenoid valve 5b is automatically exhausted, thereby preventing the first solenoid valve 5a and the second solenoid valve 5b from restarting.

[0036] First, as shown in FIG. 3, when the second solenoid valve 5b is turned off and switched to the first position 12, and the first solenoid valve 5a fails and is in the second position 13, the output line 4d leading to the air cylinder 3 is opened to the outside through the second solenoid valve 5b, so that the air in the air cylinder 3 is exhausted through the second solenoid valve 5b, and the air cylinder 3 returns to its initial position.

[0037] At this time, the pilot control line 7 is connected to the air source 2 through the first solenoid valve 5a and the second solenoid valve 5b, and control air is supplied from the air source 2 to the pilot control line 7. This control air is stored in an air tank 25 through a pilot check valve 23 and a manual relief valve 24, and is then supplied from the air tank 25 to the air control valve 20, switching the air control valve 20 to the second position 20b. This then blocks the primary line 6a and secondary line 6b of the pilot air line 6, and opens the secondary line 6b to the outside, entering an exhaust state, so that the pilot air of the first solenoid valve 5a and the second solenoid valve 5b is exhausted, and as a result, the first solenoid valve 5a and the second solenoid valve 5b cannot be restarted.

[0038] When the pilot air in the secondary line 6b is exhausted in this manner, the pilot air no longer acts on the pilot check valve 23, and the pilot check valve 23 therefore performs its original check function, preventing the control air from flowing back through the pilot control line 7 from the air operation valve 20 side toward the air source 2 side.

[0039] Furthermore, when control air is supplied to the pilot control line 7, the indicator light 26 lights up to notify the operator that one of the solenoid valves 5a, 5b has failed.

[0040] On the other hand, as shown in FIG. 4, when the first solenoid valve 5a is turned off and switched to the first position 12, and the second solenoid valve 5b has failed and is in the second position 13, the output line 4d leading to the air cylinder 3 is opened to the outside from the second solenoid valve 5b through the first relay line 4b and the first solenoid valve 5a, and the air in the air cylinder 3 is exhausted, so that the air cylinder 3 returns to its initial position.

[0041] In this case as well, the pilot control line 7 is connected to the air source 2 via the second solenoid valve 5b and the first solenoid valve 5a, and control air is supplied to the pilot control line 7, so that the pilot air of the first solenoid valve 5a and the second solenoid valve 5b is exhausted by the air control valve 20, as in the case of Fig. 3, and restart of the first solenoid valve 5a and the second solenoid valve 5b is prevented. The pilot check valve 23 and the indicator light 26 also operate in the same manner as described above.

[0042] Such an operation of the air control circuit 1A prevents the solenoid valves 5a and 5b from restarting during inspection of a malfunction, and the air cylinder 3 from starting unexpectedly.

[0043] 3 and 4, after the failure of the solenoid valve 5a or 5b is recovered, in order to make the air control circuit 1A in a state where it can be restarted, the operation lever 27 of the manual relief valve 24 is manually operated to switch the manual relief valve 24 to the second position 24b, as shown in FIG. 5. Then, the pilot control line 7 is opened, TeE Since the control air in the air tank 25 is discharged to the outside, the air operation valve 20 is switched to the first position 20a by the return spring 22, and the pilot air line 6 is put into a supply state. As a result, pilot air from the air source 2 is supplied to the first solenoid valve 5a and the second solenoid valve 5b, and the first solenoid valve 5a and the second solenoid valve 5b are put into a restartable state. Furthermore, the pilot check valve 23 conducts the pilot control line 7 in both the forward and reverse directions by the action of pilot air.

[0044] When the operation of the operating lever 27 is released, the manual relief valve 24 is returned to the first position 24a by the return spring .

[0045] In the above embodiment, the air tank 25 is connected to the pilot control line 7, but the air tank 25 does not necessarily have to be provided. Although the manual relief valve 24 is a three-port valve, a two-port valve can also be used. Fig. 6 shows a connection example when a two-port manual relief valve 24 is used. In this example, the manual relief valve 24 is connected to a relief line 7b branching off from the pilot control line 7. The manual relief valve 24 is normally in a first position 24a and blocks the relief line 7b, but when the operating lever 27 is operated, it switches to a second position 24b and opens the relief line 7b to the outside via the silencer 18, so that the control air in the pilot control line 7 is discharged to the outside.

[0046] 7 shows a second embodiment of an air control circuit according to the present invention. An air control circuit 1B of this second embodiment differs from the air control circuit 1A of the first embodiment in that the air operated valve 20 connected to the pilot air line 6 is equipped with a detent mechanism 50 for holding the air operated valve 20 in the second position 20b, and a release button 51 for releasing the hold by the detent mechanism 50.

[0047] The detent mechanism 50 has a variable member 50a that displaces integrally with the air-operated valve 20, and a locking member 50b that can lock the variable member 50a. When the air-operated valve 20 is switched to the second position 20b by control air from the pilot control line 7, the variable member 50a locks onto the locking member 50b, thereby holding the air-operated valve 20 in the second position 20b.

[0048] Further, the release button 51 is configured to release the locking member 50a from the variable member 50a by pressing the release button 51. 50 b is released, and the air operated valve 20 is allowed to be displaced toward the first position 20a by the biasing force of the return spring 22.

[0049] The reason for providing the detent mechanism 50 is that, when one of the solenoid valves 5a, 5b fails and does not switch normally, after the air operated valve 20 switches to the second position 20b by the action of the control air supplied from the pilot control line 7, air This is to prevent the solenoid valves 5a, 5b from becoming restartable when the control air no longer acts on the air operated valve 20 due to reasons such as insufficient air being retained in the tank 25, causing the air operated valve 20 to return to the first position 20a by the return spring 22, putting the pilot air line 6 into a supply state and supplying pilot air to the solenoid valves 5a, 5b.

[0050] The air control circuit 1B Before The configuration and operation of the air control circuit 1A other than the air control valve 20 are the same as those of the air control circuit 1A of the first embodiment, so the same main components are given the same reference numerals and their explanations are omitted.

[0051] The release button 51 can be configured to operate in conjunction with the depression of the operating lever 27 of the manual relief valve 24. In this case, when the operating lever 27 of the manual relief valve 24 is pressed to switch the manual relief valve 24 to the second position 24b from the state shown in FIG. 7, the release button 51 is operated, and the air operating valve 20 is switched to the first position 20a. As a result, the pilot control line 7 is put into an open state, and the control air is discharged to the outside, and the pilot air line 6 is put into a supply state, and pilot air is supplied to the solenoid valves 5a and 5b. When the pressure on the operating lever 27 is released, the manual relief valve 24 is returned to the first position 24a by the return spring 28, and the air operated valve 20 is held in the first position 20a by the return spring 22.

[0052] 8 shows a third embodiment of an air control circuit according to the present invention. The air control circuit 1C of this third embodiment differs from the air control circuit 1A of the first embodiment in that a delay mechanism 30 for delaying the start of the air cylinder 3 is connected to the main air line 4.

[0053] The delay mechanism 30 is composed of a switching valve 31 that can be switched between two positions by air and a return spring 32, and a throttle valve 33 that limits the flow rate of air, and is connected between the air source 2 and the first solenoid valve 5a.

[0054] The switching valve 31 is a three-port valve having a first port 34 connected to an input line 4a of the main air line 4, a second port 35 connected to a branch line 4e branching from the input line 4a, and a third port 36 connected to the input port 14 of the first solenoid valve 5a by a third relay line 4f, and is switched between a first position 31a in FIG. 8 and a second position 31b in FIG. 9 by feedback air fed back from an output line 4d connecting the second solenoid valve 5b and the air cylinder 3 through a feedback line 37 and by the return spring 32. The throttle valve 33 is a variable throttle valve whose flow passage cross-sectional area can be adjusted.

[0055] In the air control circuit 1C, when the switching valve 31 is in the first position 31a as shown in FIG. 8, the first solenoid valve 5a and the second solenoid valve 5b are both turned on and switched to the second position 13 (see the main air line 4 in FIG. 2), and the air source 2 and the air cylinder 3 are connected via the throttle valve 33, air from the air source 2 is supplied to the air cylinder 3 with the flow rate restricted through the throttle valve 33, so that the air cylinder 3 starts slowly.

[0056] Thereafter, when a portion of the air is fed back from the output line 4d to the switching valve 31 through the feedback line 37, as shown in FIG. 9, the switching valve 31 switches to the second position 31b, cuts off the branch line 4e connected to the throttle valve 33, and connects the input line 4a to the third relay line 4f, so that air from the air source 2 flows into the air cylinder 3 in a free flow state, causing the rod 3b of the air cylinder 3 to move forward at a normal speed.

[0057] The configuration and operation of the air control circuit 1C other than the delay mechanism 30 are the same as those of the air control circuit 1A of the first embodiment, so the same symbols are used to refer to the main identical components of both, and their explanations will be omitted.

[0058] The switching valve of the delay mechanism 30 31 Although the valve 31 is a three-port valve, a two-port valve can also be used. In this case, as shown in Fig. 10, the switching valve 31 and the throttle valve 33 are connected in parallel between the input line 4a and the third relay line 4f. As a result, when the air cylinder 3 starts, the switching valve 31 is in the first position 31a and blocks the flow path, so that air from the input line 4a flows into the third relay line 4f with the flow rate restricted by the throttle valve 33. Then, the air flows through the feedback line 37. The aforementioned When the feedback is sent to the switching valve 31, the switching valve 31 switches to the second position 31b, so that the air from the input line 4a flows through the switching valve 31 in a free flow state into the third relay line 4f.

[0059] In the air control circuit 1C of the third embodiment, the air control valve 20 may also have a detent mechanism 50 and a release button 51, similar to the air control valve 20 of the air control circuit 1B of the second embodiment.

[0060] In the illustrated embodiment, an air cylinder is shown as an example of the pneumatic device 3, but the pneumatic device 3 may be something other than an air cylinder, for example, another pilot solenoid valve that controls pneumatic devices such as an air cylinder. In this case, by connecting the output line 4d of the main air line 4 to the pilot line of the pilot solenoid valve, it is possible to perform control such as exhausting the pilot air of the pilot solenoid valve in an emergency to reset the pneumatic device.

[0061] As described above in detail, the air control circuits 1A, 1B, 1C are composed only of air circuits, and therefore have the advantages of being extremely simple in configuration and requiring low equipment costs compared to conventional systems that use solenoid valves with limit switches, sequencers, etc., and that there is no need to secure engineers who are familiar with safety functions and sequencer programs. [Explanation of symbols]

[0062] 1A, 1B, 1C Air control circuit 2 Air Source 3 Air equipment (air cylinders) 4 Major Airlines 5a First solenoid valve 5b Second solenoid valve 6. Pilot Airlines 7 Pilot Control Line 12 1st position 13 2nd position 14 input ports 15a 1st output port 15b Second output port 16a First exhaust port 16b Second exhaust port 20 Air operated valve 23 Pilot operated check valve 24 Manual relief valve 25 Air Tank 30 Delay mechanism 31 Switching valve 33 Throttle valve 50 Detent mechanism 50a Variable member 50b Locking member 51 Cancel button

Claims

1. a main air line in which two external pilot type solenoid valves are connected in series; a pilot air line that supplies pilot air to the two solenoid valves; and a pilot control line that switches the pilot air line between a supply state in which pilot air is supplied to the two solenoid valves and an exhaust state in which pilot air is exhausted from the two solenoid valves, The two solenoid valves of the main air line are two-position valves having a first position when off and a second position when on, and when both of the two solenoid valves are in the first position, they shut off the air source and the air equipment and exhaust air from the air equipment through one of the solenoid valves, and when both of the two solenoid valves are in the second position, they connect the air source and the air equipment and supply air from the air source to the air equipment, and when one of the two solenoid valves is in the first position and the other is in the second position, they shut off the air source and the air equipment and exhaust air from the air equipment through the solenoid valve in the first position, an air-operated valve having a first position for placing the pilot air line in the supply state and a second position for placing the pilot air line in the exhaust state is connected to the pilot air line; The pilot control line is configured to be connected to and disconnected from the air source by the two solenoid valves, and when the two solenoid valves are both in a first position and a second position, the pilot control line is disconnected from the air source, thereby holding the air operated valve at the first position where the pilot air line is in a supply state, and when one of the two solenoid valves is in the first position and the other is in the second position, the pilot control line is connected to the air source via the two solenoid valves, thereby switching the air operated valve to the second position where the pilot air line is in an exhaust state by control air supplied from the air source. An air control circuit with a safety function.

2. 2. The air control circuit according to claim 1, wherein the air-operated valve has a detent mechanism that holds the air-operated valve in the second position, and a release button that releases the detent mechanism.

3. A pilot-operated check valve, a manual relief valve, and the air-operated valve are connected to the pilot control line; the pilot operated check valve allows the control air to flow in a forward direction from the air source toward the air operated valve through the pilot control line and in a reverse direction opposite thereto when pilot air from the pilot air line is acting on the pilot operated check valve, and prevents the control air from flowing in the reverse direction when the pilot air is not acting on the pilot operated check valve; The manual relief valve is manually operated to switch the pilot control line from a conductive state in which the control air can flow to an open state in which the control air is discharged to the outside.

3. The air control circuit according to claim 1 or 2.

4. 4. The air control circuit according to claim 3, wherein an air tank is connected to the pilot control line, and the air tank stores the control air supplied from the air source and supplies it to the air operated valve.

5. the two solenoid valves are five-port valves each having one input port, a first output port, a second output port, a first exhaust port, and a second exhaust port; The two solenoid valves include a first solenoid valve connected to the air source side of the main air line and a second solenoid valve connected to the air equipment side of the main air line, an input port of the first solenoid valve connected to the air source, a first output port of the first solenoid valve connected to an input port of the second solenoid valve, a second output port of the first solenoid valve connected to a second exhaust port of the second solenoid valve, and the first exhaust port and the second exhaust port of the first solenoid valve being open to the outside; a first output port of the second solenoid valve connected to the air device, a second output port of the second solenoid valve connected to the pilot control line, and a first exhaust port of the second solenoid valve open to the outside; 5. An air control circuit according to claim 1, wherein the air control circuit is a valve.

6. 6. The air control circuit according to claim 1, wherein a delay mechanism for delaying the start of the air device is connected to the main air line.

7. 7. The air control circuit according to claim 6, wherein the delay mechanism is composed of a switching valve operated by air and a throttle valve that limits the flow rate of air, and when both of the two solenoid valves are turned on to connect the air source and the pneumatic equipment, air at the limited flow rate is circulated through the main air line via the throttle valve, and when a portion of the air output from the main air line to the pneumatic equipment is fed back to the switching valve, the switching valve switches to allow air from the air source to circulate in a free flow state through the main air line.

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