Switching valve

Abstract

[Problem] To provide a switching valve in which the actions of a spool valve and a detent mechanism are synchronized. [Solution] A selector valve 1A has a spool valve part 5 for switching the communication state between a plurality of ports by means of spools 8, 10 accommodated in a valve port 7 via which the ports communicate, first and second drive parts 30, 40 for driving the spools by means of a pilot fluid so as to shift the spool valve part to a plurality of switching states, and a detent mechanism part 60 for holding the spool valve part in a specific switching state. The detent mechanism part has an engagement rod 62 movably accommodated in a slide hole 74, a recess 63 provided in a spool, and a detent drive part 64 for causing the engagement rod to engage with and disengage from the recess. The detent drive part has a piston 66, a spring member 67 for biasing the engagement rod to the recess side, a pressure chamber 61b for withdrawing the engagement rod from the recess, and a communication flow passage 68 via which a pilot flow passage 44 and the second chamber 61b communicate.

Description

Switching valve 【0001】 The present invention relates to a switching valve and an ejector switching valve capable of maintaining the communication state between a plurality of ports in a specific communication state corresponding to a specific switching state by holding a spool valve portion in the specific switching state by a detent mechanism. 【0002】 A double-acting electromagnetic pilot-operated switching valve having a spool valve portion in which a spool is slidably accommodated in a valve hole in which a plurality of ports are communicated, and two electromagnetic pilot valves for driving the spool valve portion is already widely known as disclosed in, for example, Patent Document 1. And the switching valve of this Patent Document 1 further has a detent mechanism for maintaining the communication state between a plurality of ports by manually locking the spool valve portion. 【0003】 By the way, in such a conventional switching valve with a detent mechanism, from the viewpoint of safety and the like, there is a desire to hold the communication state between a plurality of ports in a specific communication state by automatically operating the detent mechanism under predetermined conditions. However, it is not always easy to synchronize the operation of the spool valve portion and the operation of the detent mechanism. 【0004】 Japanese Patent Application Laid-Open No. 2023-68924 【0005】 Therefore, the technical problem of the present invention is to provide a switching valve capable of maintaining the communication state between a plurality of ports in a specific communication state corresponding to a specific switching state by holding the spool valve portion in the specific switching state by a detent mechanism portion, and capable of synchronizing the operation of the spool valve portion and the operation of the detent mechanism portion. 【0006】To solve the above problems, the switching valve according to the present invention comprises: a spool valve section in which a spool is slidably housed in a valve bore extending in a first axial direction through which a plurality of ports are connected, and which switches the communication state between the plurality of ports; a first drive unit and a second drive unit arranged on one end and the other end of the spool valve section in the first axial direction, which apply a pressing force to the spool by supplying pilot fluid to move the spool valve section to a plurality of switching states corresponding to each communication state between the plurality of ports; a first pilot valve and a second pilot valve that supply and discharge pilot fluid to the first and second drive units; and a detent mechanism section that holds the spool valve section in a specific switching state corresponding to a specific communication state between the ports, wherein the detent mechanism section comprises: an engagement rod movably housed in a sliding bore connected to the valve bore and extending in a second axial direction perpendicular to the first axis; and provided on the spool, The spool valve has a recess that engages with the tip of the engagement rod when the spool valve is in a specific switching state, and a detent drive unit that engages and disengages the tip of the engagement rod from the recess, wherein either the first pilot valve or the second pilot valve also functions as a detent drive valve that drives the detent drive unit, and the detent drive unit has a drive piston connected to the engagement rod, a first spring member that constantly biases the engagement rod toward its tip and engages the tip with the recess, a pressure chamber that drives the engagement rod toward its base end via the drive piston by the pressure of compressed fluid and disengages the tip from the recess, and a communication passage that communicates the pressure chamber with the detent drive valve and supplies and discharges the compressed fluid to the pressure chamber in synchronization with the supply and discharge of the pilot fluid from the pilot valve which also functions as the detent drive valve. 【0007】In the switching valve, preferably, the first or second pilot valve, which also serves as the detent drive valve, and the corresponding first or second drive unit are in communication through a pilot passage, and the communication passage branches off from the pilot passage to supply and discharge a portion of the pilot fluid to the pressure chamber as the compressed fluid. In this case, more preferably, the second pilot valve also serves as the detent drive valve and is disposed on one end side of the spool valve portion in the first axial direction, the pilot passage extends between both ends of the spool valve portion in the first axial direction, the sliding hole extends in the spool valve portion in the second axial direction and penetrates the pilot passage, the sliding hole further has a sliding hole portion through which the engaging rod slides airtightly, connecting the valve hole and the pilot passage, and a through hole portion through which the engaging rod is movably inserted, the through hole portion has a larger cross-section than the engaging rod, and the communication passage is formed by the gap between the through hole portion and the engaging rod. Furthermore, more preferably, the engaging rod inserted into the sliding hole portion is fitted with a sealing member that airtightly seals the space between the engaging rod and the inner surface of the sliding hole portion. 【0008】 Preferably, when pilot fluid is supplied to the first drive unit and pilot fluid is exhausted from the second drive unit, the spool valve unit transitions to a first switching state, and when pilot fluid is exhausted from the first drive unit and pilot fluid is supplied to the second drive unit, the spool valve unit transitions to a second switching state, and either the first switching state or the second switching state is the specific switching state. More preferably, the switching valve is provided with a second spring member that constantly biases the spool toward the other end in the first axial direction, and when pilot fluid is supplied from the first and second pilot valves to the first and second drive units, the spool valve unit transitions to a third switching state. 【0009】In this case, preferably, the spool valve section comprises a first spool disposed on one end side of the valve hole and provided with the recess, and a second spool disposed on the other end side of the first spool, wherein the first drive unit is configured to press the first spool toward the other end side by supplying pilot fluid, and the second drive unit is configured to press the second spool toward the one end side by supplying pilot fluid, the second spool is further constantly biased toward the other end side by the second spring member, and when the spool valve section is in the first switching state, the first spool is displaced toward the other end side by the pressing of the first drive unit. Furthermore, the biasing force of the second spring member displaces the second spool toward the other end, and when the spool valve is in the second switching state, the second spool is displaced toward the one end by the pressure of the second drive unit against the biasing force of the second spring member, and the first spool is displaced toward the one end while the second spool is in contact with the first spool, and when the spool valve is in the third switching state, the first spool is displaced toward the other end by the pressure of the first drive unit, and the second spool is displaced toward the one end by the pressure of the second drive unit against the biasing force of the second spring member until it contacts the first spool. 【0010】Furthermore, in the switching valve, preferably, the switching valve is for supplying compressed fluid to an ejector that generates a vacuum, and the plurality of ports include a first supply port and a second supply port for supplying compressed fluid to the valve hole, a first output port connected to a negative pressure generating port for generating negative pressure of the ejector, and a second output port connected to a negative pressure breaking port for breaking the negative pressure of the ejector, and in the first switching state, the first supply port and the first output port are in communication by the first spool, and the communication between the second supply port and the second output port is blocked by the second spool, so that the compressed fluid supplied to the first supply port can be supplied from the first output port to the negative pressure generating port, and in the second switching state, the second supply port and the second output port are in communication by the second spool, and the first supply port In the third switching state, the communication between the first supply port and the first output port is cut off, allowing compressed fluid supplied to the second supply port to be supplied from the second output port to the negative pressure release port. In the third switching state, the communication between the first supply port and the first output port is cut off, and the communication between the second supply port and the second output port is cut off. The first and second pilot valves are electromagnetic pilot valves. In an emergency when the power supply to the first and second pilot valves is cut off while the spool valve section is in the first switching state or the third switching state, the engaging rod engages with the recess, holding the first spool in a position displaced to the other end, and the second spool is displaced to the other end by the second spring member, resulting in the first supply port and the first output port communicating, and the communication between the second supply port and the second output port being cut off. 【0011】Furthermore, in the switching valve, preferably, the spool valve section has a single spool slidably housed in the valve hole and provided with the recess. In this case, more preferably, the spool valve section includes a supply port for supplying compressed fluid to the valve hole, first and second output ports, and first and second discharge ports, wherein in the first switching state, the supply port and the first output port are in communication, and the second output port and the second discharge port are in communication, and in the second switching state, the supply port and the second output port are in communication, and the first output port and the first discharge port are in communication. Even more preferably, in the first axial direction, the recess is formed at one end or the other end of the spool. 【0012】 Furthermore, in the switching valve, preferably, the first and second pilot valves are arranged on one end side of the spool valve portion in the first axial direction. More preferably, the first pilot valve is arranged on one end side of the spool valve portion in the first axial direction, and the second pilot valve is arranged on the other end side of the spool valve portion in the first axial direction. 【0013】 As described above, according to the present invention, since either the first pilot valve or the second pilot valve also functions as a detent drive valve, compressed fluid can be supplied to and discharged from the detent drive unit's pressure chamber through the communication passage in sync with the supply and discharge of pilot fluid from the pilot valve that also functions as a detent drive valve. Therefore, it is possible to provide a switching valve that can synchronize the operation of the spool valve section and the operation of the detent mechanism section, thereby maintaining the communication state between multiple ports in a specific communication state. 【0014】Figure 1 is a front view of a switching valve according to the first embodiment of the present invention. Figure 1 is a left side view of the switching valve. Figure 1 is a top view of the switching valve. Figure 3 is a cross-sectional view of the switching valve taken along the line IV-IV, showing the initial state of the switching valve. Figure 4 is a cross-sectional view of the switching valve in the first switching state according to the first embodiment. Figure 4 is a cross-sectional view of the switching valve in the second switching state according to the first embodiment. Figure 5 is an enlarged cross-sectional view of the detent mechanism. Figure 6 shows a switching valve according to the second embodiment of the present invention, and is a cross-sectional view of the switching valve in its initial state. Figure 7 shows a switching valve according to the first switching state according to the second embodiment. Figure 8 shows a switching valve in the second switching state according to the second embodiment. Figure 9 shows a switching valve according to the second embodiment. Figure 1 is a cross-sectional view of the switching valve in the third switching state according to the second embodiment. Figure 1 shows a switching valve according to the third embodiment of the present invention, and is a cross-sectional view of the switching valve in the first switching state according to the first embodiment. Figure 1 is a cross-sectional view of the switching valve in the second switching state according to the third embodiment. Figure 1 shows a switching valve according to the fourth embodiment of the present invention, and is a cross-sectional view of the switching valve in the first switching state according to the first embodiment. This is a cross-sectional view of the switching valve in the second switching state in the fourth embodiment. 【0015】 A first embodiment of the switching valve according to the present invention will be described below with reference to the attached drawings. Figure 1 is a front view of the switching valve 1A according to the first embodiment of the present invention, Figure 2 is a left side view of the switching valve 1A, Figure 3 is a top view of the switching valve 1A, and Figure 4 is a cross-sectional view of the switching valve 1A taken along the line IV-IV in Figure 3, showing the initial state of the switching valve 1A. In this embodiment, a switching valve 1A that is suitably connected to an ejector E that generates negative pressure such as a vacuum will be used as an example. Furthermore, the case in which air is used as the fluid will be used as an example. 【0016】As shown in Figures 1-4, the switching valve 1A comprises a spool valve section 5 in which a first spool 8 and a second spool 10 are slidably housed in a valve hole 7 through which a plurality of ports P1, EA, A, B, P2 (hereinafter abbreviated as "P1-P2") are connected, and which switches the communication state between the plurality of ports P1-P2; a first drive unit 30 and a second drive unit 40 connected to both ends of the spool valve section 5, which operate the first and second spools 8 and 10 by supplying and discharging pilot fluid (pilot air); a first pilot valve 51 and a second pilot valve 52 that supply and discharge the pilot fluid to the first and second drive units 30 and 40; and a detent mechanism 60 that holds the spool valve section 5 in a specific switching state corresponding to a specific communication state between the plurality of ports P1-P2. Furthermore, in the first embodiment, the spool valve section 5 further includes a spring switching section that includes a switching spring member 14 (second spring member) which constantly biases the second spool 10, which will be described in detail later, toward the second drive section 40. The first and second drive sections 30, 40 and the switching spring member 14 selectively switch the first and second spools 8, 10 within the valve hole 7 to three switching states, thereby selectively switching the communication state between these multiple ports P1-P2 to three communication states corresponding to the three switching states. 【0017】 The multiple ports P1-P2 include a first supply port P1 and a second supply port P2 for introducing compressed fluid (compressed air) supplied from a fluid pressure source (not shown) into the valve hole 7, a first output port A for connecting to a negative pressure generation port H1 for generating negative pressure in the ejector E, and a second output port B for connecting to a negative pressure release port H2 for releasing negative pressure in the ejector E (see Figure 4). 【0018】Specifically, as shown in Figures 1 and 4, the switching valve 1A has one end 1a and the other end 1b at both ends in the direction of the first axis L1, and includes a valve casing 6 having the plurality of ports P1-P2 and the valve hole 7, a first drive block 29 disposed on the one end 1a side of the spool valve section 5 (i.e., the one end 1a side of the valve casing 6) and containing the first drive unit 30, a second drive block 41 as an end block disposed on the other end 1b side of the spool valve section 5 (i.e., the other end 1b side of the valve casing 6) and containing the second drive unit 40, a pilot valve section 50 disposed on the one end 1a side of the first drive block 29 and containing the first and second pilot valves 51 and 52, and a spring cover 12 disposed between the second drive block 41 and the valve casing 6 and containing the switching spring member 14. Within the valve hole 7, the first spool 8 is positioned at one end 1a, and the second spool 10 is positioned at the other end 1b of the first spool 8. 【0019】 As shown in Figure 4, the valve casing 6 is integrally formed in a rectangular parallelepiped shape from resin or metal, and the valve hole 7 penetrates between both end faces of the valve casing 6 in the direction of the first axis L1. Between the upper surface 6b of the valve casing 6 and the valve hole 7, a second pilot passage 44 for supplying and discharging pilot fluid to the second drive unit 40 is provided along the first axis L1. This second pilot passage 44 penetrates between both ends of the valve casing 6 and between both ends of the spring cover 12, which will be described in detail later, along the valve hole 7, and also extends into the interiors of the first and second drive blocks 29 and 41, respectively. The plurality of ports P1-P2 are opened on the lower surface 6a of the valve casing 6 and consist of a first supply port P1 and a second supply port P2 for introducing compressed fluid supplied from the fluid pressure source, a first output port A and a second output port B for outputting the compressed fluid supplied to the first and second supply ports P1 and P2 to the ejector E, and a discharge port EA (which is always airtightly closed in the first embodiment). 【0020】More specifically, the plurality of ports P1-P2 are configured by sequentially opening a first supply port P1, a discharge port EA, a first output port A, a second output port B, and a second supply port P2 on the lower surface 6a of the valve casing 6, from one end 1a to the other end 1b. By driving the spool valve section 5 with the first and second drive units 30 and 40, it is possible to selectively switch to one of three communication states: a first communication state (see Figure 5) in which the first supply port P1 and the first output port A are in communication and at the same time the second output port B and the second supply port P2 are blocked; a second communication state (see Figure 6) in which the first supply port P1 and the first output port A are blocked and at the same time the second supply port P2 and the second output port B are in communication; and a third communication state (see Figure 7) in which the first supply port P1 and the first output port A are blocked and at the same time the second output port B and the second supply port P2 are blocked. During the switching process, the spool valve section 5 is selectively transitioned to three switching states corresponding to the three communication states between ports P1 and P2, by supplying and discharging pilot fluid to the first and second drive units 30 and 40, respectively. 【0021】 In this application, the state in which only the first drive unit 30 of the two drive units 30 and 40 is driven and the spool valve unit 5 is shifted is called the "first switching state," the state in which only the second drive unit 40 is driven and the spool valve unit 5 is shifted is called the "second switching state," and the state in which both the first and second drive units 30 and 40 are driven and the spool valve unit 5 is shifted is called the "third switching state" (provided only in the first and second embodiments in this application). In the first embodiment, the switching state of the spool valve unit 5 corresponding to the first communication state is called the "first switching state," the switching state of the spool valve unit 5 corresponding to the second communication state is called the "second switching state," and the switching state of the spool valve unit 5 corresponding to the third communication state is called the "third switching state." Furthermore, in the first embodiment, an example in which the first communication state is called the "specific communication state" and the first switching state is called the "specific switching state" will be explained. 【0022】To explain in more detail, in the first switching state, as shown in Figure 5, the first spool 8 is displaced to the stroke end SP1 on the other end 1b side of the valve hole 7, and the second spool 10 is displaced to the stroke end SP4 on the other end 1b side of the valve hole 7. In the second switching state, as shown in Figure 6, the first spool 8 is displaced to the stroke end SP2 on the one end 1a side of the valve hole 7, and the second spool 10 comes into contact with the first spool 8 and is displaced to the stroke end SP5 on the one end 1a side of the valve hole 7. In the third switching state, as shown in Figure 7, the first spool 8 is displaced to the same displacement position (stroke end) SP3 as the displacement position SP1 in the first switching state, and the second spool 10 comes into contact with the first spool 8 and is displaced to an intermediate position SP6 between the displacement position SP5 and the displacement position SP4. 【0023】 As shown in Figure 4, the inner surface of the valve bore 7 is formed by sequentially providing a first support surface 7a, a first flow groove 7b, a first valve seat surface 7c, a second flow groove 7d, a second valve seat surface 7e, a third flow groove 7f, a third valve seat surface 7g, a fourth flow groove 7h, a fourth valve seat surface 7i, a fifth flow groove 7j, and a second support surface 7k in the direction of the first axis L1, from the opening on the end face of one end 1a of the valve casing 6 to the opening on the end face of the other end 1b of the valve casing 6. All of these are formed in an annular shape centered on the first axis L1. That is, on the inner surface of the valve bore 7, these annular valve seat surfaces 7c-7i and annular flow grooves 7b-7j are formed alternately adjacent to each other along the first axis L1. 【0024】 Furthermore, the first support surface 7a and the second support surface 7k of the valve hole 7 provide airtight and slidable support to the end of the first spool 8 on one end 1a and to the second spool 10. The first flow groove 7b communicates with the first supply port P1, the second flow groove 7d communicates with the discharge port EA, the third flow groove 7f communicates with the first output port A, the fourth flow groove 7h communicates with the second output port B, and the fifth flow groove 7j communicates with the second supply port P2. As described above, in the first embodiment, the discharge port EA is airtightly closed by a plug 20 or the like. Therefore, no fluid (air) is supplied or discharged through the discharge port EA. 【0025】The first spool 8 is formed by sequentially providing an airtight portion 8a, an annular recess 8b, and a land portion 8c in the direction of the first axis L1, from one end 1a to the other end 1b. Both the airtight portion 8a and the land portion 8c are formed in a cylindrical shape centered on the first axis L1, and the annular recess 8b is formed in an annular shape centered on the first axis L1. 【0026】 The second spool 10 is formed by sequentially providing a first land portion 10a, a first annular recess 10b, a second land portion 10c, a second annular recess 10d, an airtight portion 10e, a third annular recess 10f, and a pressed portion 10g in the direction of the first axis L1, from one end 1a to the other end 1b. The first land portion 10a, the second land portion 10c, the airtight portion 10e, and the pressed portion 10g are all formed in a cylindrical shape centered on the first axis L1, while the first annular recess 10b, the second annular recess 10d, and the third annular recess 10f are all formed in an annular shape centered on the first axis L1. 【0027】 Furthermore, annular outer surfaces are formed on the airtight portion 8a and land portion 8c of the first spool 8, and on the first land portion 10a, second land portion 10c, and airtight portion 10e of the second spool 10. Annular grooves 8e and 10j are provided on these outer surfaces, opening radially outward, and annular packings 8d and 10h are fitted within these grooves 8e and 10j. 【0028】 By doing so, the land portions 8c, 10a, and 10c are slidably fitted onto the valve seat surfaces 7c, 7e, 7g, and 7i of the valve hole 7 (i.e., positioned at the locations of the valve seat surfaces 7c, 7e, 7g, and 7i), and when the outer peripheral surfaces of their outer peripheral ends face the valve seat surfaces 7c, 7e, 7g, and 7i, the gap formed between the outer peripheral surfaces of the land portions 8c, 10a, and 10c and the valve seat surfaces 7c, 7e, 7g, and 7i of the valve hole 7 is sealed by the packings 8d and 10h, thereby preventing compressed fluid from flowing through the gap. 【0029】As shown in Figure 4, the first drive unit 30 has a first cylinder chamber 31 formed to be larger in diameter than the valve hole 7 and opening to the end face of the first drive block 29 facing the other end 1b, and a first piston 32 that is airtightly fitted into the first cylinder chamber 31 and slidably in the direction of the first axis L1. The first cylinder chamber 31 is airtightly divided by the first piston 32 into a first chamber 31a on the one end 1a side and a second chamber 31b on the other end 1b side, and is arranged coaxially with the valve hole 7 (i.e., on the first axis L1). Pilot fluid is supplied to and discharged from the first pilot valve 51 through the first pilot passage 33 in the first chamber 31a, and the second chamber 31b is in communication with the valve hole 7. The first cylinder chamber 31 is formed to have a larger diameter than the valve seat surfaces and support surfaces of the valve bore 7, and the first piston 32 can press the first spool 8 toward the other end 1b by contacting the end face of the airtight portion 8a of the first spool 8 toward the other end 1b. In addition, the movement of the first piston 32 toward the other end 1b is restricted by contacting the end face of the valve casing 6 toward the other end 1a. 【0030】 The second drive unit 40 includes a second cylinder chamber 42 provided within the second drive block 41 and a second piston 43 slidably fitted within the second cylinder chamber 42. The second cylinder chamber 42 is arranged coaxially (on the first axis L1) with the valve bore 7 and is formed to be larger in diameter than the valve seat surfaces and support surfaces of the valve bore 7, and opens to the end face of the second drive block 41 facing one end 1a. The second piston 43 has a pressing portion 43a integrally with its one end 1a side, which is arranged coaxially with the second spool 10. This pressing portion 43a abuts against the end face on the other end 1b side of the pressed portion 10g of the second spool 10, and is formed to be smaller in diameter than the insertion hole 17a of the valve bore 7 (described later) and to be insertable into and remove from the insertion hole 17a. The second cylinder chamber 42 is airtightly divided by the second piston 43 into a first chamber 42a on the other end 1b side and a second chamber 42b on the one end 1a side. The first chamber 42a of the second cylinder chamber 42 is in communication with the second pilot passage 44, and the second chamber 42b is in communication with the valve hole 7. 【0031】Furthermore, the second cylinder chamber 42 is formed to have the same inner diameter as the first cylinder chamber 31. Therefore, the pressing force exerted by the pilot fluid by the first piston 32 to push the first spool 8 toward the other end 1b, and the pressing force exerted by the pilot fluid by the second piston 43 to push the second spool 10 toward the one end 1a, are the same. 【0032】 In the spring switching section, the switching spring member 14 housed within the spring cover 12 constantly biases the second spool 10 toward the other end 1b. The spring cover 12 has a through hole 17 that penetrates between its two ends in the direction of its first axis L1, and this through hole 17 forms the portion of the valve hole 7 toward the other end 1b. The through hole 17 of the spring cover 12 is composed of an insertion hole portion 17a located toward the other end 1b and a spring housing hole portion 17b located toward the one end 1a side of the insertion hole portion 17a. In the valve hole 7, the spring housing hole portion 17b is located adjacent to the other end 1b side of the second support surface 7k and is formed to have a larger diameter than the second support surface 7k and the insertion hole portion 17a. Furthermore, the pressed portion 10g of the second spool 10 is slidably fitted into the insertion hole 17a, and the switching spring member 14 is housed in the housing hole 17b. 【0033】Specifically, the switching spring member 14 is a compression coil spring and is arranged within the spring housing hole 17b around the third annular recess 10f of the second spool 10 (i.e., around the shaft portion 11). A first spring seat 15 is arranged at one end 1a of the spring housing hole 17b so as to be movable in the direction of the first axis L1, and a second spring seat 16 is arranged at the other end 1b so as to be movable in the direction of the first axis L1. Through holes 15a and 16a are provided inside these spring seats 15 and 16, respectively, through which the shaft portion 11, which is arranged inside the third annular recess 10f, is inserted. The switching spring member 14 is compressed between the first spring seat 15 and the second spring seat 16, with both ends seated on these spring seats. In this manner, the first spring seat 15 is constantly in contact with the end face of the other end 1b of the valve casing 6 due to the biasing force of the switching spring member 14, and the second spring seat 16 is constantly biasing the second spool 10 toward the other end 1b while in contact with the pressed portion 10g of the second spool 10 due to the biasing force of the switching spring member 14. Herein, in the first embodiment, the spring cover 12, and the switching spring member 14, the first spring seat 15, the second spring seat 16, the second spool 10, and the valve hole 7, which are respectively arranged inside it, form the spring switching section and are included in the spool valve section 5. 【0034】 As shown in Figures 1 and 4, the first pilot valve 51 is connected to the first chamber 31a of the first cylinder chamber 31 through the first pilot passage 33. Therefore, when the first pilot valve 51 is energized, pilot fluid can be supplied from the first pilot valve 51 to the first chamber 31a. On the other hand, the second pilot valve 52 is connected to the first chamber 42a of the second cylinder chamber 42 through the second pilot passage 44. Therefore, when the second pilot valve 52 is energized, pilot fluid can be supplied from the second pilot valve 52 to the first chamber 42a. The first and second pilot valves 51 and 52 may be internal pilot types configured to utilize a portion of the compressed fluid supplied to the first supply port P1 and / or second supply port P2 of the switching valve 1A as pilot fluid, or they may be external pilot types that directly utilize pilot fluid supplied to an external pilot port provided on the switching valve 1A. 【0035】 Incidentally, as shown in Figure 3, the upper surface of the first drive block 29 is provided with a first operating section 55 and a second operating section 56, which are used to manually exhaust the pilot fluid in the first pilot passage 33 and the second pilot passage 44, which communicate with the first and second pilot valves 51 and 52, to the outside. Furthermore, as shown in Figure 1, a projection 53 is provided at the lower part of the other end 1b of the pilot valve section 50, which protrudes along the bottom surface of the first drive block 29, and a connector 54 is provided on the lower surface of this projection 53 for electrically connecting the first and second pilot valves 51 and 52 to electrical equipment such as an external power supply or controller. 【0036】 As shown in Figures 5 and 8, the detent mechanism 60 is located above the first spool 8 in the spool valve section 5 and on the upper surface 6b of the valve casing 6. The detent mechanism 60 includes a sliding hole 74 extending in the direction of a second axis L2 perpendicular to the first axis L1 and communicating with the valve hole 7, an engaging rod 62 housed in the sliding hole 74 so as to be movable in the direction of the second axis L2, a recess 63 provided on the first spool 8 that engages with the engaging rod 62 when the spool valve section 5 has transitioned to the specific switching state (the first switching state), and a detent drive unit 64 that engages and disengages the engaging rod 62 from the recess 63. 【0037】 The engagement rod 62 is a rod-shaped member extending in the vertical direction (direction of the second axis L2). When the first spool 8 is displaced to the stroke end SP1 on the other end 1b, it moves downward and the lower end (tip) of the engagement rod 62 engages with the recess 63. 【0038】 The sliding hole 74 penetrates the second pilot passage 44. More specifically, the sliding hole 74 has a sliding hole portion 76 through which the engaging rod 62 slides airtightly in the vertical direction, connecting the valve hole 7 and the second pilot passage 44, and a through hole portion 75 through which the engaging rod 62 is inserted so as to be movable in the vertical direction, penetrating between the second pilot passage 44 and the second chamber 61b of the detent drive unit 64 (described later), and the through hole portion 75 opens to the upper surface 6b of the valve casing 6 and communicates with the second chamber 61b. 【0039】 The recess 63 is provided on the outer circumferential surface of the airtight portion 8a of the first spool 8 such that, when the first spool 8 is displaced to the stroke end SP1 on the other end 1b side, the central axis L3 of the recess 63 is coaxial with the second axis L2. In this embodiment, the recess 63 is provided in an annular shape on the outer circumferential surface of the airtight portion 8a. 【0040】 As shown in Figure 8, the detent drive unit 64 includes a drive piston 66 coaxially connected and fixed to the upper end (base end) of the engagement rod 62, a first spring member 67 that constantly biases the engagement rod 62 toward the tip to engage with the recess 63, a second chamber 61b (pressure chamber) that drives the engagement rod 62 toward the base end to disengage from the recess 63 via the drive piston 66 by the pressure of the compressed fluid, and a communication passage 68 that supplies and discharges compressed fluid from the second pilot valve 52 to the second chamber 61b. In other words, in the first embodiment, the second pilot valve 52 shown in Figure 1 also serves as the detent drive valve that drives the detent drive unit 64. 【0041】 The drive piston 66 is provided within a detent block 65 installed on the upper surface 6b of the valve casing 6. Specifically, the detent block 65 has a rod drive cylinder chamber 61 inside, which opens at the lower end of the detent block 65 and communicates with the insertion hole 75. The drive piston 66 is housed within the rod drive cylinder chamber 61 so as to be slidable in the direction of the second axis L2, and the drive piston 66 airtightly divides the rod drive cylinder chamber 61 into a second chamber 61b located on the valve hole 7 side and a first chamber 61a located on the opposite side of the valve hole 7. The upper end (base end) of the engagement rod 62 is integrally connected to the center of the lower surface of the drive piston 66 on the valve hole 7 side. 【0042】The first spring member 67 is positioned within the first chamber 61a around the second axis L2 of a projection 70 that protrudes from the upper surface of the drive piston 66 and is formed to have a smaller diameter than the piston 66. The upper end of the first spring member 67 abuts against the upper end surface (top surface) of the rod drive cylinder chamber 61, and the lower end abuts against the upper surface of the drive piston 66, in a compressed state, thereby constantly biasing the drive piston 66 downward. Specifically, the first spring member 67 is a compression coil spring. Furthermore, the first chamber 61a of the rod drive cylinder chamber 61 is provided with a ventilation hole 71 that is in constant communication with the outside. With this configuration, when compressed fluid is exhausted from the second chamber 61b, the biasing force of the first spring member 67 moves the engagement rod 62 toward its tip. Furthermore, when compressed fluid is supplied to the second chamber 61b from the second pilot valve 52 (detent-driven valve), the engaging rod 62 moves toward its base end against the biasing force of the first spring member 67. 【0043】 Here, the engagement rod 62 and the first spring member 67 will be described in more detail with reference to Figures 5 and 8. The compressed fluid supplied from the first supply port P1 passes through the gap between the valve hole 7 and the first spool 8 (airtight portion 8a) to the tip of the engagement rod 62, and the pressure of the compressed fluid constantly acts on the tip as a pressing force toward the base end. For this reason, the biasing force (spring constant) of the first spring member 67 needs to be large enough to allow the engagement rod 62 to be inserted into the recess 63 against this fluid pressure when no pilot fluid is supplied to the second chamber 61b (exhaust state). Also, when pilot fluid is supplied to the second chamber 61b from the second pilot passage 44, a pilot pressure toward the base end acts on the engagement rod 62 through the drive piston 66, causing it to withdraw from the recess 63. Therefore, the biasing force (spring constant) of the first spring member 67 needs to be small enough to allow the entire tip of the engaging rod 62 to be disengaged from the recess 63, compared to the pressing force acting on the drive piston 66 by the pilot pressure. 【0044】The communication flow path 68 branches from the second pilot flow path 44 and communicates with the second chamber 61b. More specifically, the insertion hole portion 75 is formed to have a larger diameter than the engagement rod 62 and has a larger cross-sectional area, and an annular gap 77 is formed between the outer peripheral surface of the engagement rod 62 and the inner surface of the insertion hole portion 75. This gap 77 extends in the vertical direction and communicates the second pilot flow path 44 and the second chamber 61b, thereby forming the communication flow path 68. Therefore, a part of the pilot fluid is supplied as compressed fluid to the second chamber 61b from the second pilot flow path 44 through the communication flow path 68, and the compressed fluid is exhausted from the second chamber 61b to the second pilot flow path 44 through the communication flow path 68. 【0045】 Here, although the detent block 65 is installed on the upper surface 6b of the valve casing 6, there is a possibility that the compressed fluid (pilot fluid) flowing through the communication flow path 68 may leak from between the upper surface 6b of the valve casing 6 and the lower surface of the detent block 65. Therefore, a circular recess 72 having a larger diameter than the opening of the rod driving cylinder chamber 61 is provided on the upper surface 6b of the valve casing 6 where the communication flow path 68 opens, and a packing 73 is attached to the inner peripheral surface of this circular recess 72. For this reason, the packing 73 can make the contact between the detent block 65 and the valve casing 6 airtight, thereby preventing the leakage of the compressed fluid. 【0046】 A seal member 78 that always seals the space between the engagement rod 62 and the inner surface of the sliding hole portion 76 is attached to the lower part of the engagement rod 62 inserted through the sliding hole portion 76. For this reason, it is possible to prevent the compressed fluid in the valve hole 7 from flowing into the second pilot flow path 44 or the pilot fluid in the second pilot flow path 44 from flowing into the valve hole 7. 【0047】Next, based on FIGS. 4 to 7, the operation of the switching valve 1A will be described. FIG. 4 shows the switching valve 1A in its initial state. Since the first and second pilot valves 51 and 52 are not energized, pilot fluid is not supplied to the first and second drive units 30 and 40, and these drive units 30 and 40 are open to the atmosphere through the pilot valves 51 and 52. Then, the first and second spools 8 and 10 are displaced toward the one end 1a side and the other end 1b side. Also, since no compressed fluid is supplied to the detent mechanism unit 60, the engagement rod 62 abuts against the outer peripheral surface on the other end 1b side rather than the recess 63 in the airtight portion 8a of the first spool 8 by the biasing force of the first spring member 67. That is, in the direction of the first axis L1, with the first spool 8 displaced toward the one end 1a side, the central axis L3 of the recess 63 is arranged at a non-coaxial displaced position with respect to the second axis L2 (see FIG. 4). 【0048】 Then, as shown in FIG. 5, when the first pilot valve 51 is energized to supply pilot fluid to the first drive unit 30 and the second pilot valve 52 (detent drive valve) is not energized to exhaust pilot fluid from the second drive unit 40, the spool valve unit 5 shifts to the first switching state which is the specific switching state, and the engagement rod 62 is engaged with the recess 63. More specifically, for example, from the initial state shown in FIG. 4, when the first drive unit 30 is driven by pilot fluid and the exhaust of pilot fluid from the second drive unit 40 is maintained, the spool valve unit 5 shifts to the first switching state in which the first spool 8 is displaced to the stroke end SP1 on the other end 1b side and the second spool 10 is displaced to the stroke end SP4 on the other end 1b side. Then, the central axis L3 of the recess 63 is arranged coaxially with the second axis L2, and the engagement rod 62 is engaged with the recess 63 by the biasing force of the first spring member 67. That is, the first spool 8 is held at the stroke end SP1 on the other end 1b side by the detent mechanism unit 60, and the second spool 10 is held at the stroke end SP4 on the other end 1b side by the biasing force of the switching spring member 14. 【0049】At this time, the communication state between the multiple ports P1-P2 becomes the "specific communication state" in which the first supply port P1 and the first output port A are connected by the first spool 8, and the communication between the second supply port P2 and the second output port B is blocked by the second spool 10, and the compressed fluid output from the first output port A is supplied to the negative pressure generation port H1 of the ejector E. For example, if this ejector E is connected to a suction pad, the negative pressure generated by the ejector E causes the workpiece to be attracted to the suction pad. 【0050】 On the other hand, as shown in Figure 6, when pilot fluid is exhausted from the first drive unit 30 and pilot fluid is supplied to the second drive unit 40, the engagement rod 62 moves toward its base end and disengages from the recess 63, the second spool 10 is displaced to the stroke end SP5 on the one end 1a side, and the first spool 8 is pressed toward the one end 1a side by the second spool 10 and displaced to the stroke end SP2 on the one end 1a side. As a result, the spool valve portion 5 of the switching valve 1A transitions to the second switching state. At that time, the central axis L3 of the recess 63 moves to a position shifted toward the one end 1a side than the second axis L2, and the tip of the engagement rod 62 is positioned on the outer circumferential surface of the airtight portion 8a toward the other end 1b side than the recess 63. 【0051】 At this time, the second spool 10 connects the second supply port P2 and the second output port B, while the first spool 8 and the second spool 10 block the connection between the first supply port P1 and the first output port A, causing the compressed fluid supplied to the second supply port P2 to be output from the second output port B. The compressed fluid output from the second output port B is then supplied to the negative pressure release port H2 of the ejector E. For example, if the ejector E is connected to a suction pad and a workpiece is held in place by negative pressure, the compressed fluid supplied to the negative pressure release port H2 will release the negative pressure (vacuum), causing the workpiece to detach from the suction pad. 【0052】Then, as shown in Figure 7, when pilot fluid is supplied to the first and second drive units 30 and 40 respectively, the engagement rod 62 moves toward its base end and disengages from the recess 63. With the first drive unit 30 pressing, the first spool 8 is displaced to the stroke end SP3 on the other end 1b side, and the second spool 10 is displaced toward the one end 1a side to the intermediate position SP6 where it contacts the first spool 8, due to the pressure of the second drive unit 40 against the biasing force of the switching spring member 14. In other words, as described above, the pressing force acting on the first and second spools 8 and 10 from the first piston 32 and the second piston 43 due to the supply of pilot fluid is the same for both, but the second spool 10 is constantly biased toward the other end 1b side by the switching spring member 14. Therefore, the pressing force acting from the second spool 10 toward one end 1a on the first spool 8 is smaller than the pressing force acting from the first piston 32 toward the other end 1b on the first spool 8. Consequently, the first piston 32 is maintained in a stopped state at the stroke end on the other end 1b, and the first spool 8 is maintained in a stopped state at the stroke end SP3 on the other end 1b. 【0053】 As a result, the spool valve section 5 of the switching valve 1A transitions to the third switching state. At this time, the central axis L3 of the recess 63 is arranged coaxially with the second axis L2, but because pilot fluid is supplied to the second drive unit 40, the engaging rod 62 remains in a state moved toward the base end and does not engage with the recess 63. At this time, the communication between the first supply port P1 and the first output port A, and the communication between the second supply port P2 and the second output port B are both blocked by the second spool 10, and the output of compressed fluid from the switching valve 1A is stopped. For example, if the ejector E is connected to a suction pad and the state transitions from the first switching state to the third switching state, the negative pressure inside the suction pad is maintained and the workpiece is kept in a suction state. 【0054】Incidentally, when the switching valve 1A is used connected to the ejector E as described above, in an emergency when the power supply to the first and second pilot valves 51 and 52 is cut off while the suction pad is holding a workpiece in the first or third switching state shown in Figure 5 or Figure 7, it is desirable for safety reasons that the workpiece be held in a suction state. In this embodiment, in such an emergency, the engagement rod 62 engages with the recess 63 by stopping the supply of pilot fluid. As a result, the spool valve 5 is held in the first switching state, with the first spool 8 displaced to the stroke end SP1 on the other end 1b side, and the switching spring member 14 displaced the second spool 10 to the stroke end SP4 on the other end 1b side. Thus, the first supply port P1 and the first output port A are in communication, and the communication between the second supply port P2 and the second output port B is cut off. As a result, the compressed fluid supplied to the first supply port P1 can be supplied from the first output port A to the negative pressure generation port H1 of the ejector E, and the adsorption state of the workpiece is maintained. 【0055】 Furthermore, if the power supply to the first and second pilot valves 51 and 52 is interrupted when the spool valve section 5 is in the second switching state shown in Figure 6 and the workpiece is released from the suction pad by vacuum breaking, the first spool 8 remains at the stroke end on one end 1a, and the second spool 10 is displaced to the stroke end on the other end 1b by the switching spring member 14, causing the spool valve section 5 to return to the initial state. As a result, the supply of compressed fluid from the second output port B to the negative pressure breaking port H2 is stopped by the second spool 10, and the supply of compressed fluid from the switching valve 1A to the ejector E is stopped. 【0056】Furthermore, in an emergency when the power supply to the first and second pilot valves 51 and 52 is cut off while the spool valve section 5 is in the third switching state shown in Figure 7, if the flow rate of pilot fluid exhausted from the first pilot valve 51 is greater than the flow rate of pilot fluid exhausted from the second pilot valve 52, the pressing force acting on the first spool 8 in the direction of the first axis L1 may be smaller in the direction of the other end 1b than in the direction of the one end 1a. In this case, the first spool 8 will be displaced towards the one end 1a side by the pressing force of the second spool 10, and the central axis L3 of the recess 63 will be misaligned with the second axis L2 of the sliding hole 74, preventing the engagement rod 62 from engaging with the recess 63. For this reason, a throttling mechanism may be provided in the passage through which the pilot fluid is exhausted from the first pilot valve 51. In this way, the flow rate of pilot fluid exhausted from the first pilot valve 51 becomes less than the flow rate of pilot fluid exhausted from the second pilot valve 52, preventing the first spool 8 from moving toward one end 1a and ensuring that the engaging rod 62 is reliably engaged with the recess 63. 【0057】 Thus, according to the switching valve 1A of this embodiment, compressed fluid can be supplied to and discharged from the second pilot valve 52 to the second chamber 61b, which is the pressure chamber of the detent mechanism 60, from the second pilot valve 52, which also serves as the detent drive valve, in synchronization with the supply and discharge of pilot fluid from the second pilot valve 52 to the second drive unit 40 that drives the spool valve unit 5. Therefore, with a simple structure, it is possible to synchronize the operation of the spool valve unit 5 and the operation of the detent mechanism 60, and to maintain the communication state between multiple ports P1, EA, A, B, P2 in a "specific communication state," which is a first communication state, or to release that maintenance. Furthermore, if, for example, an ejector E is connected to this switching valve 1A and a suction pad is connected to the ejector E, safety can be ensured by maintaining the state in which the suction pad is holding the workpiece even in an emergency when the power supply is cut off. 【0058】Next, a second embodiment of the switching valve according to the present invention will be described, mainly based on Figures 9 to 12. Here, the explanation will focus on the parts that differ from the first embodiment, and detailed explanations of parts common to both will be omitted to avoid duplication. The main differences between the first embodiment and this second embodiment are that, in the first embodiment, the second pilot valve 52 also served as the detent drive valve, whereas in this second embodiment, the first pilot valve 51 also serves as the detent drive valve; and, in the first embodiment, the "specific switching state" in which the detent mechanism 60 functions was the first switching state, and the first communication state corresponding to that switching state was the "specific communication state," whereas in this second embodiment, the "specific switching state" is the second switching state, and the second communication state corresponding to that switching state is the "specific communication state" (Figure 11). 【0059】 In other words, in the first embodiment, pilot fluid was supplied to and discharged from the second pilot valve 52, which acts as a detent drive valve, as compressed fluid through the communication passage 68 to the second chamber 61b (see Figure 8). In the second embodiment, however, pilot fluid is supplied to and discharged from the first pilot valve 51, which acts as a detent drive valve, as compressed fluid through the communication passage 68 to the second chamber 61b. Specifically, as shown in Figure 9, the communication passage 68 is branched from the first pilot passage 33 connected to the first pilot valve 51, and this communication passage 68 is connected to the second chamber 61b through the first drive block 29 and the valve casing 6. For this reason, the detent mechanism 60 of the second embodiment does not have a communication passage 68 formed by the gap 77 between the insertion hole 75 and the engaging rod 62, as in the first embodiment. 【0060】 In this second embodiment, as shown in Figure 11, when the spool valve section 5 is in the "specific switching state" which is the second switching state, the recess 63 is recessed into the outer circumferential surface of the airtight section 8a such that the central axis L3 of the recess 63 is coaxial with the second axis L2 of the sliding hole 74. 【0061】In addition, the detent drive unit 64 has the same structure as the first embodiment except for the structure of the communication passage 68, so we will explain it here using Figure 8. That is, in the second embodiment, the detent drive unit 64 has the drive piston 66, the first spring member 67, the second chamber 61b (pressure chamber), and the communication passage 68 that supplies and discharges compressed fluid from the first pilot valve 51 to the second chamber 61b. 【0062】 In the switching valve 1B according to this second embodiment, when the spool valve section 5 is in its initial state, as shown in Figure 9, the first and second pilot valves 51 and 52 are not energized, so the first and second spools 8 and 10 are displaced toward the one end 1a and the other end 1b. Also, since no compressed fluid is supplied to the detent mechanism section 60, the engaging rod 62 is engaged with the recess 63 by the biasing force of the first spring member 67. That is, in the direction of the first axis L1, with the first spool 8 displaced toward the one end 1a, the central axis L3 of the recess 63 is arranged coaxially with the second axis L2 of the sliding hole section 76, and the first spool 8 is held at the stroke end SP2 toward the one end 1a by the detent mechanism section 60. 【0063】 Then, as shown in Figure 10, in the switching valve 1B, when the first pilot valve 51 is energized and pilot fluid is supplied to the first drive unit 30, and when the second pilot valve 52 is de-energized and pilot fluid is exhausted from the second drive unit 40, compressed fluid is supplied from the first pilot valve 51, which acts as a detent drive valve, to the second chamber 61b through the communication passage 68. Then, the engaging rod 62 moves toward the base end together with the drive piston 66 against the biasing force of the first spring member 67, and the engaging rod 62 is disengaged from the recess 63. As a result, the first spool 8 moves to the stroke end SP1 on the other end 1b side, and the second spool 10 moves to the stroke end SP4 on the other end 1b side due to the biasing force of the switching spring member 14. 【0064】As a result, the spool valve section 5 of the switching valve 1B transitions to the first switching state, and the multiple ports P1-P2 enter the first communication state. At this time, the engaging rod 62 does not engage with the recess 63, but is in contact with the outer circumferential surface of the airtight portion 8a of the first spool 8 on the side of the recess 63 to one end 1a. Furthermore, if, for example, the first output port A of the switching valve 1B is connected to the negative pressure release port H2 of the ejector E, the second output port B is connected to the negative pressure generation port H1 of the ejector E, and the ejector E is attached to a suction pad, compressed air for negative pressure (vacuum) release is supplied to the suction pad. 【0065】 Furthermore, as shown in Figure 11, in the switching valve 1B, when pilot fluid is exhausted from the first drive unit 30 by the first pilot valve 51 and pilot fluid is supplied to the second drive unit 40 by the second pilot valve 52, the second spool 10 moves to the stroke end SP5 on one end 1a, and the first spool 8 is also pressed by the second spool 10 and moves to the stroke end SP2 on one end 1a. As a result, the spool valve section 5 of the switching valve 1B transitions to the second switching state, which is a "specific switching state," and the plurality of ports P1-P2 enter the second communication state, which is a "specific communication state." At this time, the compressed fluid in the second chamber 61b is exhausted through the communication passage 68 and the first pilot valve 51, and the central axis L3 of the recess 63 is positioned coaxially with the second axis L2, and the tip of the engaging rod 62 engages with the recess 63. As a result, the detent mechanism 60 holds the first spool 8 at the stroke end SP2 on one end 1a. 【0066】When the communication state between the multiple ports P1-P2 is in the second communication state (a specific communication state), the first spool 8 blocks the communication between the first supply port P1 and the first output port A, and the second spool 10 connects the second supply port P2 and the second output port B. The compressed fluid output from the second output port B is then supplied to the negative pressure generation port H1 of the ejector E. At this time, for example, if the ejector E is connected to a suction pad, the negative pressure generated by the ejector E causes the workpiece to be attracted to the suction pad. 【0067】 Then, as shown in Figure 12, when pilot fluid is supplied to both the first and second drive units 30 and 40 in the switching valve 1B, the pilot fluid from the first pilot valve 51 moves the engagement rod 62 toward its base end, releasing its engagement with the recess 63. Then, similar to the first embodiment, the first spool 8 moves to the stroke end SP3 on the other end 1b side, and the second spool 10 moves to the intermediate position SP6, and the spool valve section 5 of the switching valve 1B transitions to the third switching state. At this time, similar to the first embodiment, communication between the first and second output ports A and B and the first and second supply ports P1 and P2 is cut off, and the output of compressed fluid from the switching valve 1B is stopped. For this reason, for example, when the ejector E connected to the switching valve 1B is connected to a suction pad, and the system transitions from the second switching state to the third switching state, the negative pressure in the suction pad is maintained, and the suction state of the workpiece is maintained. 【0068】Next, a third embodiment of the switching valve according to the present invention will be described, mainly based on Figures 13 and 14. Here again, the explanation will focus on the parts that differ from the first embodiment, and detailed explanations of parts common to both will be omitted to avoid duplication. The differences between the first embodiment and this third embodiment are mainly in the configuration of the spool valve section 5 and the configuration of the port opened in the valve casing 6. In the first embodiment, two spools, namely the first spool 8 and the second spool 10, were housed in the valve hole 7, but in the third embodiment, as shown in Figures 13 and 14, only one spool, the third spool 80, is housed in the valve hole 7. Furthermore, the spool valve section 5 does not have the spring switching section for transitioning the spool valve section 5 to the third switching state. For this reason, the second drive block 41 is directly connected to the end face on the other end 1b side of the valve casing 6. 【0069】 In this case, the spool valve section 5 is capable of selectively transitioning between two positions: the first switching state (Figure 13), which is the "specific switching state" where the third spool 80 is displaced to the stroke end on the other end 1b side by the drive of the first drive unit 30, and the second switching state (Figure 14), where the third spool 80 is displaced to the stroke end on the one end 1a side by the drive of the second drive unit 40. That is, the spool valve section 5 of the switching valve 1C according to this third embodiment does not have a spring switching section (i.e., a switching spring member 14) like the first and second embodiments, so there is no third switching position. In the first switching state where the third spool 80 is displaced to the other end 1b side, the recess 63 is opened on the outer circumferential surface of the airtight portion 80a of the third spool 80 such that the central axis L3 of the recess 63 is coaxial with the second axis L2 of the sliding hole 74. Furthermore, in this third embodiment as well, the detent mechanism 60 has the same structure as in the first embodiment, and the second chamber 61b of the detent drive unit 64 is connected to the second pilot valve 52, which also serves as the detent drive valve, by a communication passage 68 having the same structure as in the first embodiment. 【0070】On the bottom surface of the switching valve 1C, a first discharge port EA, a first output port A, a supply port P, a second output port B, and a second discharge port EB are provided, extending from one end 1a to the other end 1b. When the first drive unit 30 is driven by the supply of pilot fluid and the pilot fluid is exhausted from the second drive unit 40 in the state shown in Figure 14 (second switching state), the third spool 80 is displaced to the stroke end on the other end 1b side, as shown in Figure 13, and the spool valve unit 5 transitions to the first switching state, which is the "specific switching state" in the third embodiment. Then, the engaging rod 62 engages with the recess 63 due to the downward (tip side) biasing force by the first spring member 67, and the spool valve unit 5 is held in the first switching state, or the "specific switching state". At this time, the communication state between the multiple ports EA, A, P, B, and EB is the fourth communication state, which is the "specific communication state" in the third embodiment, in which the supply port P and the first output port A, and the second output port B and the second discharge port EB are in communication, while the communication between the first output port A and the first discharge port EA, and the communication between the supply port P and the second output port B are blocked. 【0071】 Furthermore, in the state shown in Figure 13 (first switching state (specific switching state)), when pilot fluid is exhausted from the first drive unit 30 and the second drive unit 40 is driven by the supply of pilot fluid, as described above, the engagement rod 62 is disengaged from the recess 63 by the compressed fluid from the second pilot valve 52, and the engagement between the two is released. Then, as shown in Figure 14, the third spool 80 is displaced to the stroke end on one end 1a, and the spool valve unit 5 transitions to the second switching state. At this time, the communication state between the multiple ports EA, A, P, B, EB is a fifth communication state in which communication between the supply port P and the first output port A, and communication between the second output port B and the second discharge port EB are blocked, and communication is established between the first output port A and the first discharge port EA, and between the supply port P and the second output port B. 【0072】Next, a fourth embodiment of the switching valve according to the present invention will be described with reference to Figures 15 and 16. Here, the explanation will focus on the parts that differ from the third embodiment, and detailed explanations of parts common to both will be omitted to avoid duplication. The main differences between the third embodiment and this fourth embodiment are that, in the third embodiment, the second pilot valve 52 also served as the detent drive valve, whereas in this fourth embodiment, the first pilot valve 51 also serves as the detent drive valve; and, in the third embodiment, the "specific switching state" in which the detent mechanism 60 functions was the first switching state, and the first communication state corresponding to that switching state was the "specific communication state," whereas in this fourth embodiment, the "specific switching state" is the second switching state, and the fifth communication state corresponding to that switching state is the "specific communication state" (Figure 16). 【0073】 In other words, in the third embodiment, pilot fluid was supplied to and discharged from the second pilot valve 52, which acts as a detent drive valve, as compressed fluid through the communication passage 68 to the second chamber 61b (see Figures 8, 13, and 14). In the fourth embodiment, however, pilot fluid is supplied to and discharged from the first pilot valve 51, which acts as a detent drive valve, as compressed fluid through the communication passage 68 to the second chamber 61b. Specifically, as shown in Figure 15, the communication passage 68 is branched from the first pilot passage 33 connected to the first pilot valve 51, and this communication passage 68 is connected to the second chamber 61b through the first drive block 29 and the valve casing 6. For this reason, the detent mechanism 60 of the switching valve 1D in the fourth embodiment does not have a communication passage 68 formed by the gap 77 between the insertion hole 75 and the engaging rod 62, as in the third embodiment. 【0074】 In this fourth embodiment, as shown in Figure 16, when the spool valve section 5 is in the "specific switching state" which is the second switching state, the recess 63 is recessed into the outer circumferential surface of the airtight section 8a such that the central axis L3 of the recess 63 is coaxial with the second axis L2 of the sliding hole 74. 【0075】In this fourth embodiment, in the state shown in Figure 16 (second switching state (specific switching state)), when the first drive unit 30 is driven by the supply of pilot fluid and the pilot fluid is exhausted from the second drive unit 40, the engagement rod 62 is disengaged from the recess 63 by the compressed fluid from the first pilot valve 51, and the engagement between the two is released. Then, as shown in Figure 15, the third spool 80 is displaced to the stroke end on the other end 1b side, and the spool valve unit 5 transitions to the first switching state. At this time, the communication state between the multiple ports EA, A, P, B, EB is the fourth communication state. 【0076】 Furthermore, in the state shown in Figure 15 (first switching state), when pilot fluid is exhausted from the first drive unit 30 and the second drive unit 40 is driven by the supply of pilot fluid, as shown in Figure 16, the third spool 80 is displaced to the stroke end on one end 1a side, and the spool valve portion 5 of the switching valve 1D transitions to the second switching state, which is the "specific switching state" in the fourth embodiment. Then, the engaging rod 62 engages with the recess 63 due to the downward (tip side) biasing by the first spring member 67, and the spool valve portion 5 is held in the second switching state, or "specific switching state". At this time, the communication state between the multiple ports EA, A, P, B, EB is the fifth communication state corresponding to that "specific switching state". 【0077】 In the first and second embodiments described above, the communication passage 68 is shown as branching off from the second pilot passage 44 and the first pilot passage 33 and communicating with the second chamber 61b, but the invention is not limited thereto. For example, the communication passage may directly connect the second pilot valve 52 to the second chamber 61b, and the first pilot valve 51 to the second chamber 61b. 【0078】 Furthermore, while the first and third embodiments illustrate a configuration in which the communication channel 68 is formed by the gap 77 between the engaging rod 62 and the insertion hole 75, the invention is not limited thereto. For example, the communication channel may be provided separately from the insertion hole 75 and connect the second pilot channel 44 and the second chamber 61b. 【0079】Furthermore, while the first to fourth embodiments illustrate a configuration in which the first and second pilot valves 51 and 52 are arranged on one end 1a side of the spool valve section 5, the invention is not limited to this configuration. For example, one of the first and second pilot valves 51 and 52 may be arranged on one end 1a side of the spool valve section 5, and the other on the other end 1b side of the spool valve section 5. 【0080】 Furthermore, while the third and fourth embodiments illustrate a configuration in which the detent mechanism 60 is disposed at one end 1a of the valve casing 6, the configuration is not limited thereto. For example, the detent mechanism 60 may be disposed at the other end 1b of the valve casing 6. 【0081】 1A, 1B, 1C, 1D Switching valve 5 Spool valve section 7 Valve hole 8 First spool (spool) 10 Second spool (spool) 12 Spring cover 14 Switching spring member (second spring member) 30 First drive unit 33 First pilot passage (pilot passage) 40 Second drive unit 44 Second pilot passage (pilot passage) 51 First pilot valve (detent drive valve) 52 Second pilot valve (detent drive valve) 60 Detent mechanism section 61b Second chamber (pressure chamber) 62 Engagement rod 63 Recess 64 Detent drive unit 66 Drive piston (piston) 67 First spring member 68 Communication passage 74 Sliding hole 75 Through hole section 76 Sliding hole section 77 Gap 78 Seal member 80 Third spool (spool) A First output port (port) B Second output port (port) E Ejector EA Discharge port, first discharge port (port) H1 Negative pressure generation port H2 Negative pressure release port L1 First axis L2 Second axis P Supply port P1 First supply port (port) P2 Second supply port (port)

Claims

1. A switching valve comprising: a spool valve section in which a spool is slidably housed in a valve bore extending in a first axial direction through which a plurality of ports are connected, and which switches the communication state between the plurality of ports; a first drive unit and a second drive unit arranged on one end and the other end of the spool valve section in the first axial direction, which apply a pressing force to the spool by supplying pilot fluid to move the spool valve section to a plurality of switching states corresponding to each communication state between the plurality of ports; a first pilot valve and a second pilot valve that supply and discharge pilot fluid to the first and second drive units; and a detent mechanism section that holds the spool valve section in a specific switching state corresponding to a specific communication state between the ports, The detent mechanism comprises: an engaging rod movably housed in a sliding hole connected to the valve hole and extending in a second axial direction perpendicular to the first axis; a recess provided on the spool that engages with the tip of the engaging rod when the spool valve is in a specific switching state; and a detent drive unit that engages and disengages the tip of the engaging rod from the recess; wherein either the first pilot valve or the second pilot valve also functions as a detent drive valve that drives the detent drive unit; and the detent drive unit comprises: a drive piston connected to the engaging rod; a first spring member that constantly biases the engaging rod toward its tip and engages the tip with the recess; and a pressure chamber that drives the engaging rod toward its base end via the drive piston by the pressure of a compressed fluid and disengages the tip from the recess.

2. The switching valve according to claim 1, wherein the first or second pilot valve, which also serves as the detent drive valve, and the corresponding first or second drive unit are in communication through a pilot passage, and the communication passage branches off from the pilot passage to supply and discharge a portion of the pilot fluid to the pressure chamber as the compressed fluid.

3. The switching valve according to claim 2, wherein the second pilot valve also serves as the detent drive valve and is disposed on one end side of the spool valve portion in the first axial direction, the pilot passage extends between both ends of the spool valve portion in the first axial direction, the sliding hole extends in the spool valve portion in the second axial direction and penetrates the pilot passage, the sliding hole further has a sliding hole portion through which the engaging rod slides airtightly, connecting the valve hole and the pilot passage, and a through hole portion through which the engaging rod is movably inserted, the through hole portion has a larger cross-section than the engaging rod, and the communication passage is formed by the gap between the through hole portion and the engaging rod.

4. The switching valve according to claim 3, characterized in that the engaging rod inserted through the sliding hole is fitted with a sealing member that airtightly seals the space between the engaging rod and the inner surface of the sliding hole.

5. The switching valve according to claim 1, characterized in that when pilot fluid is supplied to the first drive unit and pilot fluid is exhausted from the second drive unit, the spool valve unit transitions to a first switching state, when pilot fluid is exhausted from the first drive unit and pilot fluid is supplied to the second drive unit, the spool valve unit transitions to a second switching state, and either the first switching state or the second switching state is the specific switching state.

6. The switching valve is provided with a second spring member that constantly biases the spool toward the other end in the first axial direction, and the spool valve section is moved to a third switching state when pilot fluid is supplied from the first and second pilot valves to the first and second drive units, as described in claim 5.

7. The spool valve section comprises a first spool disposed on one end side of the valve hole and provided with the recess, and a second spool disposed on the other end side of the first spool, the first drive unit is configured to press the first spool toward the other end side by supplying pilot fluid, and the second drive unit is configured to press the second spool toward the one end side by supplying pilot fluid, the second spool is further constantly biased toward the other end side by the second spring member, and when the spool valve section is in the first switching state, the first spool is displaced toward the other end side by the pressing of the first drive unit, and the second spool is displaced toward the other end side by the biasing force of the second spring member. The switching valve according to claim 6, characterized in that when the spool valve is in the second switching state, the second spool is displaced toward the one end by the pressure of the second drive unit against the biasing force of the second spring member, and the first spool is displaced toward the one end while the second spool is in contact with the first spool, and when the spool valve is in the third switching state, the first spool is displaced toward the other end by the pressure of the first drive unit, and the second spool is displaced toward the one end until it comes into contact with the first spool by the pressure of the second drive unit against the biasing force of the second spring member.

8. A switching valve according to claim 7, wherein the switching valve is for supplying compressed fluid to an ejector that generates a vacuum, and the plurality of ports include a first supply port and a second supply port for supplying compressed fluid to the valve hole, a first output port for connecting to a negative pressure generating port for generating negative pressure of the ejector, and a second output port for connecting to a negative pressure breaking port for breaking negative pressure of the ejector, wherein in the first switching state, the first supply port and the first output port are in communication by the first spool, and the communication between the second supply port and the second output port is blocked by the second spool, so that compressed fluid supplied to the first supply port can be supplied from the first output port to the negative pressure generating port. In the second switching state, the second spool connects the second supply port and the second output port, and the first spool blocks the connection between the first supply port and the first output port, so that compressed fluid supplied to the second supply port can be supplied from the second output port to the negative pressure release port; In the third switching state, the connection between the first supply port and the first output port is blocked, and the connection between the second supply port and the second output port is blocked; The first and second pilot valves are solenoid pilot valves; An ejector switching valve characterized in that, in an emergency when the power supply to the first and second pilot valves is cut off while the spool valve section is in the first switching state or the third switching state, the engaging rod engages with the recess, holding the first spool in a position displaced toward the other end, and the second spool is displaced toward the other end by the second spring member, thereby creating a state in which the first supply port and the first output port are in communication, and the communication between the second supply port and the second output port is cut off.

9. The switching valve according to claim 5, characterized in that the spool valve portion has a single spool that is slidably housed in the valve hole and has the recess provided therein.

10. The switching valve according to claim 9, wherein the spool valve section includes a supply port for supplying compressed fluid to the valve hole, first and second output ports, and first and second discharge ports, and in the first switching state, the supply port and the first output port are in communication, and the second output port and the second discharge port are in communication, and in the second switching state, the supply port and the second output port are in communication, and the first output port and the first discharge port are in communication.

11. The switching valve according to claim 9 or 10, characterized in that the recess is formed at one end or the other end of the spool in the first axial direction.

12. The switching valve according to claim 1 or 2, characterized in that the first and second pilot valves are arranged on one end side of the spool valve portion in the first axial direction.

13. The switching valve according to claim 1 or 2, characterized in that the first pilot valve is disposed on one end side of the spool valve portion in the first axial direction, and the second pilot valve is disposed on the other end side of the spool valve portion in the first axial direction.

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