Fluid supply control device

Abstract

A fluid supply control device (12) comprises: a first fluid control unit (30) that supplies a driving fluid to a first chamber (R1) in an actuator (14); a second fluid control unit (32) into which flows a second discharge fluid discharged from a second chamber (R2) in the actuator; a flow path switching unit (34) that causes the driving fluid to flow into one of the first fluid control unit and the second fluid control unit by switching a flow path; and a switching control unit (36) that causes the flow path switching unit to switch the flow path into which the driving fluid flows if a second chamber pressure (P2) in the second chamber is lower than a prescribed pressure (Pt).

Description

Fluid supply control device

[0001] The present disclosure relates to a fluid supply control device.

[0002] Japanese Unexamined Patent Application Publication No. 2022-70433 discloses a door opening / closing device for a machine tool that drives a door with a fluid pressure cylinder. The door opening / closing device can reduce impact when the door of the machine tool stops at an open position or a closed position.

[0003] There is a possibility that the door of a machine tool may move and come into contact with obstacles such as humans and objects. Improvement of safety when a door contacts an obstacle is highly desired.

[0004] An object of the present disclosure is to solve the problems described above.

[0005] An aspect of the present disclosure is a fluid supply control device that controls supply of driving fluid to an actuator, the actuator internally including a movable body movable by supply of the driving fluid from a fluid supply valve, the actuator moving a door of a machine tool by movement of the movable body, the fluid supply control device comprising: a first fluid control unit that supplies the inflowing driving fluid to a first chamber in the actuator, or into which a first discharged fluid discharged from the first chamber flows; a second fluid control unit into which a second discharged fluid discharged from a second chamber in the actuator flows, the second chamber being adjacent to the first chamber across the movable body, or that supplies the inflowing driving fluid to the second chamber; a flow path switching unit that has flow paths respectively connected to the first fluid control unit and the second fluid control unit, and switches the flow paths to cause the driving fluid from the fluid supply valve to flow into one of the first fluid control unit and the second fluid control unit; and a switching control unit that, when a pressure in the second chamber becomes lower than a predetermined pressure in a state where the driving fluid is supplied to the first chamber, transmits the supply pressure of the driving fluid to the flow path switching unit, thereby causing the flow path switching unit to switch the flow path to allow the driving fluid to flow from the flow path connected to the first fluid control unit to the flow path connected to the second fluid control unit.

[0006] According to the present disclosure, safety is improved when the door of a machine tool comes into contact with an obstacle.

[0007] Figure 1 illustrates a fluid supply control device when the door is open. Figure 2 illustrates the temporal change in the door displacement. Figure 3 illustrates the temporal change in the first chamber pressure of the first chamber and the second chamber pressure of the second chamber of the actuator, and the temporal change in the door displacement. Figures 4A and 4B illustrate the temporal change in the first chamber pressure and the second chamber pressure of the actuator, and the temporal change in the door displacement. Figure 5 illustrates a fluid supply control device when the door is in the process of closing. Figure 6 illustrates a fluid supply control device when the door is in the process of closing. Figure 7 illustrates a fluid supply control device when the door is in the process of closing. Figure 8 illustrates a fluid supply control device at the time the door is closed and thereafter. Figure 9 illustrates a fluid supply control device when the door stops in the process of closing.

[0008] A fluid supply control device according to one embodiment will be described with reference to Figures 1 to 9. The actuator to which fluid is supplied by the fluid supply control device according to this embodiment moves the door of a machine tool.

[0009] Figure 1 illustrates a fluid supply control device 12 when the door 10 is open. The actuator 14 that moves the door 10 of the machine tool has a movable body 14b inside. The movable body 14b is, for example, a piston that can move within a cylinder. A rod that moves along with the movement of the piston within the cylinder moves the door 10. In other words, the actuator 14 moves the door 10 by the movement of the movable body 14b. The movable body 14b is movable when the driving fluid from the fluid supply valve 16 is supplied to the actuator 14.

[0010] The fluid supply valve 16 supplies fluid from the fluid supply source S to the actuator 14 as a driving fluid via the fluid supply control device 12. In this embodiment, the fluid from the fluid supply source S is air. The flow path within the fluid supply valve 16 is switched by electromagnetic control depending on whether the door 10 is open or closed.

[0011] When driving fluid is supplied to the first chamber R1 within the actuator 14, the piston, which is the moving body 14b, moves in a direction D away from the bottom of the cylinder. The first chamber R1 is the space within the cylinder formed by the piston, which is the moving body 14b, and the bottom of the cylinder. The second chamber R2 within the actuator 14 is the space within the cylinder adjacent to the first chamber R1, separated by the piston, which is the moving body 14b. As the moving body 14b moves in direction D, the volume of the first chamber R1 increases and the volume of the second chamber R2 decreases. Consequently, the fluid that had been accumulating in the second chamber R2 is discharged as a second discharge fluid, as will be described later.

[0012] As described above, the rod moves as the movable body 14b moves in direction D, causing the door 10 to move and close. When the movable body 14b reaches the end position of its range of movement, the door 10 closes. The closing of the door 10 triggers a switching operation of the limit valve 18 that it contacts. As a result, the fluid supply control device 12 can perform a predetermined operation in response to the movable body 14b reaching its end position. Details of the switching operation of the limit valve 18 and the predetermined operation of the fluid supply control device 12 that accompanies it will be described later.

[0013] The fluid supply control device 12 controls the supply of drive fluid from the fluid supply valve 16 to the actuator 14. The fluid supply control device 12 includes a first fluid control unit 30, a second fluid control unit 32, a flow path switching unit 34, a switching control unit 36, a pressure regulating valve 38, a switching suppression unit 40, a fluid timer 42, a shuttle valve 44, and an exhaust device 46.

[0014] When drive fluid flows from the flow path switching section 34 to the first fluid control unit 30, the first fluid control unit 30 supplies the incoming drive fluid to the first chamber R1 in the actuator 14. When the first discharge fluid is discharged from the first chamber R1 and flows into the first fluid control unit 30, the first fluid control unit 30 limits the flow rate of the incoming first discharge fluid. The first fluid control unit 30 discharges the first discharge fluid to the outside of the fluid supply control device 12 through the exhaust device 46.

[0015] As described above, Figure 1 illustrates the fluid supply control device 12 when the door 10 is opened. Prior to this, during the process of the door 10 opening, the drive fluid is supplied to the second chamber R2, and the first discharge fluid is discharged from the first chamber R1. The moving body 14b moves in direction E, opposite to the direction D described above. As a result, the door 10 opens. As the moving body 14b moves in direction E, the volume of the first chamber R1 decreases, and the volume of the second chamber R2 increases.

[0016] From this point onward, during the process of closing the door 10, as will be described later using Figures 5 to 7, a driving fluid is supplied to the first chamber R1 and a second discharge fluid is discharged from the second chamber R2. The moving body 14b moves in the direction D described above. As a result, the door 10 closes.

[0017] The first fluid control unit 30 includes a directional control valve 30da, a directional control valve 30db, a first pressure reducing valve 30pa, a second pressure reducing valve 30pb, and a flow control valve 30f.

[0018] The directional control valves 30da and 30db switch the flow paths within their respective interiors. This allows the directional control valves 30da and 30db to switch the flow direction of the drive fluid circulating within the first fluid control unit 30 when the drive fluid is supplied to the first chamber R1. In other words, the directional control valves 30da and 30db realize three different paths through which the drive fluid supplied to the first chamber R1 circulates within the first fluid control unit 30. These three paths include the first path U1, the second path U2, and the third path U3, which will be described later.

[0019] The first pressure reducing valve 30pa reduces the fluid pressure of the drive fluid flowing into the first pressure reducing valve 30pa when the drive fluid is supplied to the first chamber R1. The second pressure reducing valve 30pb reduces the fluid pressure of the drive fluid flowing into the second pressure reducing valve 30pb when the drive fluid is supplied to the first chamber R1. The amount of pressure reduction by the second pressure reducing valve 30pb is greater than the amount of pressure reduction by the first pressure reducing valve 30pa. In other words, the second pressure reducing valve 30pb reduces the fluid pressure of the drive fluid more than the first pressure reducing valve 30pa.

[0020] The first path U1 is a path through which the driving fluid flows from the flow path switching section 34 through the directional control valves 30da and 30db without passing through either the first pressure reducing valve 30pa or the second pressure reducing valve 30pb. When the driving fluid flows along the first path U1, the fluid pressure of the driving fluid is not reduced by the first pressure reducing valve 30pa and the second pressure reducing valve 30pb. In this case, the driving fluid is supplied to the first chamber R1 without being reduced in pressure. In the example shown in Figure 1, the first path U1 is realized within the first fluid control unit 30.

[0021] Directional control using the directional control valve 30da allows the first path U1 to be switched to the second path U2. The second path U2 is a path through which the drive fluid flows from the flow path switching section 34 through the first pressure reducing valve 30pa and then through the directional control valves 30da and 30db. When the drive fluid flows along the second path U2, the fluid pressure of the drive fluid is reduced by the first pressure reducing valve 30pa. When the drive fluid flows along the second path U2, the drive fluid is supplied to the first chamber R1 at a lower pressure than when it flows along the first path U1.

[0022] Directional control using the directional control valve 30db can switch the second path U2 to the third path U3. The third path U3 is a path through which the drive fluid flows from the flow path switching section 34 through the second pressure reducing valve 30pb and then through the directional control valve 30db. When the drive fluid flows along the third path U3, the fluid pressure of the drive fluid is reduced by the second pressure reducing valve 30pb. When the drive fluid flows along the third path U3, the drive fluid is supplied to the first chamber R1 at a lower pressure than when it flows along the second path U2.

[0023] Figure 1 shows a state in which a drive fluid is supplied to the second chamber R2 and a first discharge fluid is discharged from the first chamber R1. The flow control valve 30f limits the flow rate of the first discharge fluid discharged from the first chamber R1 when a drive fluid is supplied to the second chamber R2. This makes it possible to limit the movement speed of the moving body 14b moving in direction E. In other words, it is possible to control the speed at which the door 10 opens. The first discharge fluid flows along the first path U1 in the first fluid control unit 30 and is discharged to the outside of the fluid supply control device 12 through the exhaust device 46.

[0024] When drive fluid flows from the flow path switching section 34 to the second fluid control unit 32, the second fluid control unit 32 supplies the incoming drive fluid to the second chamber R2 in the actuator 14. In this case, as described above, the movable body 14b moves in direction E, and the door 10 opens. When the second discharge fluid is discharged from the second chamber R2 and flows into the second fluid control unit 32, the second fluid control unit 32 limits the flow rate of the incoming second discharge fluid. The second fluid control unit 32 discharges the second discharge fluid to the outside of the fluid supply control device 12 through the exhaust device 46. In this case, as described above, the movable body 14b moves in direction D, and the door 10 closes.

[0025] The second fluid control unit 32 includes a first flow control valve 32fa, a second flow control valve 32fb, a third flow control valve 32fc, a first flow control switching valve 32da, and a second flow control switching valve 32db.

[0026] As described above, during the closing of the door 10, the drive fluid is supplied to the first chamber R1, and the second discharge fluid is discharged from the second chamber R2. The first flow control switching valve 32da and the second flow control switching valve 32db switch the internal flow paths of each when the drive fluid is supplied to the first chamber R1. As a result, the first flow control switching valve 32da and the second flow control switching valve 32db switch the flow direction of the second discharge fluid circulating within the second fluid control unit 32.

[0027] In other words, the first flow control switching valve 32da and the second flow control switching valve 32db realize three types of paths through which the second discharge fluid flows within the second fluid control unit 32. The three types of paths include the first path V1, the second path V2, and the third path V3, which will be described later. Depending on which of these three types of paths the second discharge fluid flows along, the flow rate of the second discharge fluid flowing within the second fluid control unit 32 is switched.

[0028] The first flow control valve 32fa is located in the first path V1. When the driving fluid is supplied to the first chamber R1, the first flow control valve 32fa limits the flow rate of the second discharge fluid that is discharged from the second chamber R2 and flows into the first flow control valve 32fa.

[0029] The second flow control valve 32fb is located in the second path V2. The second flow control valve 32fb limits the flow rate of the second discharge fluid that is discharged from the second chamber R2 and flows into the second flow control valve 32fb when the drive fluid is supplied to the first chamber R1.

[0030] The third flow control valve 32fc is located in the third path V3. The third flow control valve 32fc limits the flow rate of the second discharge fluid that is discharged from the second chamber R2 and flows into the third flow control valve 32fc when the drive fluid is supplied to the first chamber R1.

[0031] These mechanisms allow the movement speed of the moving body 14b moving in direction D to be limited. In other words, the speed at which the door 10 closes can be controlled. When the supply of driving fluid to the first chamber R1 is started so that the open door 10 closes, the discharge of the second discharge fluid from the second chamber R2 is started. At that time, the first flow control switching valve 32da causes the second discharge fluid to flow into the first flow control valve 32fa. The first flow control valve 32fa starts limiting the flow rate of the second discharge fluid. The second discharge fluid flows along the first path V1.

[0032] Directional control using the first flow control switching valve 32da can switch the first path V1 to the second path V2. In this case, the first flow control switching valve 32da switches the internal flow path. As a result, the first flow control switching valve 32da switches the flow control valve that allows the second discharge fluid to flow in from the first flow control valve 32fa to the second flow control valve 32fb.

[0033] The first flow control switching valve 32da switches from the first flow control valve 32fa to the second flow control valve 32fb at time T1, which is a predetermined time Tq1 after time T0, when the first flow control valve 32fa begins to limit the flow rate of the second discharge fluid. The second flow control valve 32fb begins to limit the flow rate of the second discharge fluid. The second discharge fluid flows along the second path V2.

[0034] The amount of flow restriction by the second flow control valve 32fb is greater than the amount of flow restriction by the first flow control valve 32fa. In other words, the flow rate of the second discharge fluid restricted by the second flow control valve 32fb is less than the flow rate of the second discharge fluid restricted by the first flow control valve 32fa. The opening degrees of the first flow control valve 32fa and the second flow control valve 32fb are set in this manner. Therefore, by switching the flow control valve that allows the second discharge fluid to flow in from the first flow control valve 32fa to the second flow control valve 32fb, the movement speed of the moving body 14b can be reduced. That is, the speed at which the door 10 closes can be slowed down.

[0035] Directional control using the second flow control switching valve 32db can switch the second path V2 to the third path V3. In this case, the second flow control switching valve 32db switches the internal flow path. As a result, the second flow control switching valve 32db switches the flow control valve that allows the second discharge fluid to flow in from the second flow control valve 32fb to the third flow control valve 32fc.

[0036] The second flow control switching valve 32db switches from the second flow control valve 32fb to the third flow control valve 32fc at time T2, which is a predetermined time Tq2 after time T0, when the first flow control valve 32fa begins to limit the flow rate of the second discharge fluid. The third flow control valve 32fc begins to limit the flow rate of the second discharge fluid. The second discharge fluid flows along the third path V3.

[0037] The second flow control switching valve 32db may switch from the second flow control valve 32fb to the third flow control valve 32fc after a predetermined time Tq2-Tq1 has elapsed from the time T1 when the second flow control valve 32fb begins to limit the flow rate of the second discharge fluid.

[0038] The amount of flow restriction by the third flow control valve 32fc is greater than the amount of flow restriction by the second flow control valve 32fb. In other words, the flow rate of the second discharge fluid restricted by the third flow control valve 32fc is less than the flow rate of the second discharge fluid restricted by the second flow control valve 32fb. The second flow control valve 32fb and the third flow control valve 32fc are set in this manner. Therefore, by switching the flow control valve that allows the second discharge fluid to flow in from the second flow control valve 32fb to the third flow control valve 32fc, the movement speed of the moving body 14b can be further reduced. That is, the speed at which the door 10 closes can be made even slower.

[0039] The second discharge fluid flows along the first path V1, the second path V2, or the third path V3 within the second fluid control unit 32 and is discharged to the outside of the fluid supply control device 12 through the exhaust device 46.

[0040] Figure 1 shows a state in which the drive fluid is supplied to the second chamber R2 and the first discharge fluid is discharged from the first chamber R1. The first flow control switching valve 32da and the second flow control switching valve 32db supply the drive fluid flowing from the flow path switching section 34 to the first flow control valve 32fa to the second chamber R2. The first flow control valve 32fa has a check valve (not shown). When the drive fluid is supplied to the second chamber R2, the drive fluid flows through the check valve, so the first flow control valve 32fa does not restrict the flow rate of the drive fluid flowing into the first flow control valve 32fa.

[0041] Flow paths from the flow path switching unit 34 are connected to the first fluid control unit 30 and the second fluid control unit 32, respectively. The flow path switching unit 34 switches the flow paths, thereby allowing the drive fluid from the fluid supply valve 16 to flow into either the first fluid control unit 30 or the second fluid control unit 32.

[0042] The flow path switching unit 34 includes a direction control valve 34a and a direction control valve 34b. When the driving fluid from the fluid supply valve 16 flows through the direction control valve 34a, it then flows through the direction control valve 34b. The driving fluid may flow through the direction control valve 34b without flowing through the direction control valve 34a. The driving fluid that has flowed through the direction control valve 34b is further supplied to the first chamber R1 or the second chamber R2 via the first fluid control unit 30 or the second fluid control unit 32 at a further downstream position.

[0043] The switching control unit 36 causes the flow path switching unit 34 to switch the flow path into which the driving fluid flows. That is, the flow path for introducing the driving fluid is switched from the flow path connected to the first fluid control unit 30 to the flow path connected to the second fluid control unit 32. The switching of the flow path is performed when the second chamber pressure P2 in the second chamber R2 becomes lower than a predetermined pressure Pt in a state where the driving fluid is supplied to the first chamber R1. The switching of the flow path is performed by the switching control unit 36 transmitting the supply pressure of the driving fluid to the flow path switching unit 34. The details thereof will be described later with reference to Fig. 9. Note that the predetermined pressure Pt is transmitted from the switching suppression unit 40 as described later.

[0044] The switching control unit 36 includes a direction control valve 36a and a direction control valve 36b. In the example shown in Fig. 1, the pressure transmitted from the switching suppression unit 40 to the switching control unit 36 is the predetermined pressure Pt. Also, the second chamber pressure P2 is higher than the predetermined pressure Pt. In this case, the atmospheric pressure Po is transmitted from the direction control valve 36a to the direction control valve 36b, and the atmospheric pressure Po is also output from the direction control valve 36b.

[0045] The pressure regulating valve 38 regulates the supply pressure of the driving fluid flowing into the switching suppression unit 40 from the flow path switching unit 34 to the predetermined pressure Pt. The predetermined pressure Pt is lower than the supply pressure of the driving fluid. The predetermined pressure Pt is determined such that the second chamber pressure P2 becomes higher than the predetermined pressure Pt while the moving body 14b moves in the direction D. Further, the predetermined pressure Pt can be determined according to a design value of a response time Te described later. The opening degree of the pressure regulating valve 38 is set based on the predetermined pressure Pt determined in this manner.

[0046] The switching suppression unit 40 is a directional control valve. The switching suppression unit 40 transmits the predetermined pressure Pt adjusted by the pressure adjusting valve 38 or the atmospheric pressure Po to the switching control unit 36. As described above, in the example shown in Fig. 1, the predetermined pressure Pt is transmitted from the switching suppression unit 40 to the switching control unit 36.

[0047] In addition, as will be described later with reference to Fig. 8, the switching suppression unit 40 blocks the transmission of the predetermined pressure Pt to the switching control unit 36 in response to the movable body 14b reaching the end position. In this case, the switching suppression unit 40 transmits the atmospheric pressure Po to the switching control unit 36. Thereby, the switching suppression unit 40 can suppress the switching of the flow path for allowing the driving fluid to flow in by the flow path switching unit 34 when such switching is unnecessary.

[0048] As described above, the switching control unit 36 can cause the flow path switching unit 34 to switch the flow path through which the driving fluid flows in. At this timing, a part of the driving fluid from the flow path switching unit 34 can be supplied to the fluid timer 42 via the flow path switching unit 34 and the switching control unit 36. The fluid timer 42 includes a fluid timer 42A and a fluid timer 42B. Each fluid timer 42 includes a flow rate control valve 42v and a tank 42t. The flow rate control valve 42v limits the flow rate of the fluid supplied to the fluid timer 42. The fluid having the flow rate limited by the flow rate control valve 42v is stored in the tank 42t.

[0049] The pressure in the tank 42t of the fluid timer 42A is transmitted to the first flow rate control switching valve 32da of the second fluid control unit 32 and the directional control valve 30da of the first fluid control unit 30. The pressure in the tank 42t of the fluid timer 42B is transmitted to the second flow rate control switching valve 32db of the second fluid control unit 32 and the directional control valve 30db of the first fluid control unit 30. As the storage amount of the fluid stored in the tank 42t increases, the pressure in the tank 42t rises.

[0050] The amount of flow restriction by the flow control valve 42v of fluid timer 42A is smaller than the amount of flow restriction by the flow control valve 42v of fluid timer 42B. In other words, the fluid flow rate restricted by the flow control valve 42v of fluid timer 42A is greater than the fluid flow rate restricted by the flow control valve 42v of fluid timer 42B. Therefore, the pressure in the tank 42t of fluid timer 42A rises faster than the pressure in the tank 42t of fluid timer 42B.

[0051] As described above, the switching control unit 36 ​​causes the flow path switching unit 34 to switch the flow path, thereby initiating the inflow of the drive fluid from the flow path switching unit 34 to the first fluid control unit 30. The drive fluid that has flowed through the first fluid control unit 30 is supplied to the first chamber R1. When the drive fluid is supplied to the first chamber R1, the first flow control valve 32fa begins to limit the flow rate of the second discharge fluid. That is, at the time T0 described above, the supply of drive fluid to the first chamber R1 begins, and the first flow control valve 32fa begins to limit the flow rate of the second discharge fluid.

[0052] Furthermore, as described above, at the timing when the switching control unit 36 ​​causes the flow path switching unit 34 to switch the flow path, the pressure in the tanks 42t of both fluid timers 42A and 42B begins to rise. That is, at the time T0 described above, the pressure in the tanks 42t of both fluid timers 42A and 42B begins to rise. At time T1, after the predetermined time Tq1 described above has elapsed from time T0, when the first flow control valve 32fa begins to limit the flow rate of the second discharge fluid, the pressure in the tank 42t of fluid timer 42A reaches a predetermined operating pressure value Pa.

[0053] This causes a switch in the direction of fluid flow between the directional control valve 30da of the first fluid control unit 30 and the first flow control switching valve 32da of the second fluid control unit 32. Specifically, the first flow control switching valve 32da of the second fluid control unit 32 switches the first path V1 to the second path V2. The directional control valve 30da of the first fluid control unit 30 switches the first path U1 to the second path U2.

[0054] In other words, a switch in the fluid flow path occurs at time T1, which is a predetermined time Tq1 after time T0, when the first flow control valve 32fa begins to limit the flow rate of the second discharge fluid. At time T1, the first fluid control unit 30 reduces the pressure of the drive fluid through the first pressure reducing valve 30pa and then allows it to flow into the first fluid control unit 30, thereby allowing it to flow along the second path U2. At time T1, the second fluid control unit 32 allows the second discharge fluid to flow into the second flow control valve 32fb, thereby allowing it to flow along the second path V2. Thus, at time T1, the second flow control valve 32fb begins to limit the flow rate of the second discharge fluid.

[0055] This allows for a reduction in the response time Te until the closing door 10 begins to move in the opening direction, as will be described later, thus improving safety.

[0056] At time T2, after a predetermined time Tq2 has elapsed from time T0, when the first flow control valve 32fa begins limiting the flow rate of the second discharge fluid, the pressure in the tank 42t of the fluid timer 42B reaches a predetermined operating pressure value Pb. Note that time T2 is later than time T1.

[0057] This causes a switch in the direction of fluid flow between the directional control valve 30db of the first fluid control unit 30 and the second flow control switching valve 32db of the second fluid control unit 32. Specifically, the second flow control switching valve 32db of the second fluid control unit 32 switches the second path V2 to the third path V3. The directional control valve 30db of the first fluid control unit 30 switches the second path U2 to the third path U3.

[0058] In other words, a switch in the fluid flow path occurs at time T2, which is a predetermined time Tq2 after time T0, when the first flow control valve 32fa begins to limit the flow rate of the second discharge fluid. At time T2, the first fluid control unit 30 reduces the pressure of the drive fluid through the second pressure reducing valve 30pb and then allows it to flow into the first fluid control unit 30, thereby allowing it to flow along the third path U3. At time T2, the second fluid control unit 32 allows the second discharge fluid to flow into the third flow control valve 32fc, thereby allowing it to flow along the third path V3. Thus, at time T2, the third flow control valve 32fc begins to limit the flow rate of the second discharge fluid.

[0059] This allows for a shorter response time Te, which will be discussed later, thus improving safety.

[0060] The shuttle valve 44 has two input ports 44ia and 44ib and one output port 44o. The shuttle valve 44 outputs the higher of the two fluid pressures flowing into the two input ports 44ia and 44ib from the output port 44o.

[0061] When the first exhaust fluid is discharged from the first chamber R1, the exhaust device 46 discharges the first exhaust fluid to the outside of the fluid supply control device 12. When the second exhaust fluid is discharged from the second chamber R2, the exhaust device 46 discharges the second exhaust fluid to the outside of the fluid supply control device 12. In this embodiment, the exhaust device 46 is a silencer attached to the exhaust port of the directional control valve 34b of the flow path switching unit 34.

[0062] Figure 2 is a diagram illustrating the temporal change in the displacement A of the door 10. Some time after the aforementioned time T0, when the supply of the driving fluid to the first chamber R1 begins and the flow rate of the second discharge fluid is restricted by the first flow control valve 32fa, the displacement A of the door 10 begins to increase.

[0063] The value of the displacement amount A of the door 10 at time T1 described above is A1. At time T1, the switching from the first flow control valve 32fa to the second flow control valve 32fb occurs, which reduces the movement speed of the moving body 14b. As a result, the speed at which the door 10 closes slows down. Therefore, the increase in the displacement amount A of the door 10 per unit time after time T1 is smaller than before time T1.

[0064] The value of the displacement amount A of the door 10 at the aforementioned time T2 is A2. At time T2, the switching from the second flow control valve 32fb to the third flow control valve 32fc occurs, further reducing the movement speed of the moving body 14b. As a result, the speed at which the door 10 closes becomes even slower. Therefore, the increase in the displacement amount A of the door 10 per unit time after time T2 becomes smaller than before time T2.

[0065] The value of the displacement A of door 10 at time T3 is A3. When the displacement A of door 10 reaches the value A3, door 10 is in a closed state. Therefore, the value of the displacement A of door 10 remains A3 after time T3.

[0066] Figure 3 illustrates the temporal changes in the first chamber pressure P1 of the first chamber R1 and the second chamber pressure P2 of the second chamber R2 of the actuator 14, as well as the temporal changes in the displacement A of the door 10. However, Figure 3 shows an example where the door 10 stops closing due to being obstructed by an obstacle J such as a person, and then opens again. In the initial state, the door 10 is open. In this case, as a result of the first discharge fluid being discharged from the first chamber R1, no fluid remains in the first chamber R1. Therefore, the first chamber pressure P1 of the first chamber R1 is equal to atmospheric pressure Po. At this point, fluid remains in the second chamber R2. The value of the second chamber pressure P2 is P2x.

[0067] At the aforementioned time T0, the drive fluid is supplied to the first chamber R1, and the first flow control valve 32fa begins to limit the flow rate of the second discharge fluid. Due to the supply of the drive fluid to the first chamber R1, at time T0, the pressure P1 in the first chamber begins to rise from atmospheric pressure Po. In response to the rise in the pressure P1 in the first chamber, the moving body 14b is pressed in the direction D. At the same time, the second discharge fluid begins to be discharged from the second chamber R2. As a result, at time T0, the pressure P2 in the second chamber begins to fall from the value P2x.

[0068] Furthermore, the movable body 14b begins to move in direction D due to the pressure it receives. As a result, the volume of the first chamber R1 increases and the volume of the second chamber R2 decreases. The open door 10 begins to close, and the displacement A of the door 10 increases.

[0069] Suppose that at a subsequent time Tc, the door 10 comes into contact with the obstacle J. The value of the first room pressure P1 at time Tc is P1c. The value of the second room pressure P2 at time Tc is P2c. The value of the second room pressure P2 P2c at time Tc is higher than the predetermined pressure Pt by a difference G.

[0070] Door 10 decelerates upon contact with obstacle J, and the increase in displacement A becomes gradual. That is, the movement speed of the moving body 14b decreases, and the decrease in the volume of the second chamber R2 also becomes gradual. Since the flow rate of the second discharge fluid discharged from the second chamber R2 remains unchanged, the pressure P2 inside the second chamber begins to decrease. Subsequently, the pressure P2 inside the second chamber becomes lower than the predetermined pressure Pt.

[0071] Therefore, as described above, the switching control unit 36 ​​causes the flow path switching unit 34 to switch the flow path through which the driving fluid flows. Due to this switching, the driving fluid that was flowing into the first fluid control unit 30 flows into the second fluid control unit 32. The driving fluid is supplied to the second chamber R2 beyond the second fluid control unit 32. The first discharge fluid is discharged from the first chamber R1.

[0072] Therefore, at time Tr, after the second chamber pressure P2 has fallen below the predetermined pressure Pt, the value of the displacement A, which had been increasing up to that point, stops at Am. That is, the door 10 stops because it is blocked by an obstacle J, such as a person, while in the process of closing. The moving body 14b stops before the aforementioned end position. Also, as the driving fluid is supplied to the second chamber R2, the second chamber pressure P2 begins to rise at time Tr. In response to the rise in the second chamber pressure P2, the moving body 14b is pressed in the direction E. At the same time, the first discharge fluid begins to be discharged from the first chamber R1. As a result, the first chamber pressure P1 begins to decrease at time Tr.

[0073] Furthermore, due to being pressed, the moving body 14b begins to move in the direction of direction E at time Tm immediately afterward. That is, the direction of movement of the moving body 14b reverses. At the same time, the volume of the second chamber R2 increases, and the volume of the first chamber R1 decreases. Since the door 10 begins to open again, the displacement amount A of the door 10 decreases from the value Am after time Tm. At time Ts, the displacement amount A of the door 10 returns to zero. That is, after time Ts, the door 10 is in the open state. The pressure in the first chamber P1 continues to decrease and returns to atmospheric pressure Po. The pressure in the second chamber P2 continues to increase and returns to the value P2x.

[0074] Therefore, if the open door 10 comes into contact with the obstacle J while closing, it will start to open again after a response time Te has elapsed from that point. This improves safety when the door 10 comes into contact with the obstacle J. The response time Te is the time from the time Tc when the closing door 10 comes into contact with the obstacle J to the time Tm when the door 10 begins to move in the opening direction. The shorter the response time Te, the greater the safety.

[0075] Figures 4A and 4B illustrate the temporal changes in the first and second chamber pressures P1 and P2 of the actuator 14, and the temporal changes in the displacement A of the door 10. Explanations of parts similar to those in Figure 3 are omitted in Figures 4A and 4B. However, Figures 4A and 4B show an example where the door 10 closes without being obstructed by an obstacle J. In the initial state, the door 10 is open.

[0076] As described above, at time T0, the drive fluid is supplied to the first chamber R1, and the first flow control valve 32fa begins to limit the flow rate of the second discharge fluid. At time T1, the value of the displacement amount A of the door 10 becomes A1. Also at time T1, the flow control valves are switched, and the second flow control valve 32fb begins to limit the flow rate of the second discharge fluid. As described above, this switching reduces the movement speed of the movable body 14b, and the speed at which the door 10 closes can be slowed down.

[0077] At time T2, the value of the displacement A of the door 10 becomes A2. At time T2, the flow control valve is switched, and the third flow control valve 32fc begins to limit the flow rate of the second discharge fluid. As described above, this switch further reduces the movement speed of the movable body 14b, making it possible to slow down the closing speed of the door 10.

[0078] This stepwise control takes into account the impact resistance of a person when the obstacle J is a person. During the period from time T0 to time T1, the door 10 opens wide. Therefore, there is a possibility that the door 10 will come into contact with the person's torso while closing. During the period from time T1 to time T2, the door 10 opens narrowly, so there is no possibility of the door 10 coming into contact with the person's torso while closing, but there is a possibility of it coming into contact with the person's head. The head is less resistant to impact from contact with the door 10 than the torso. Therefore, it is preferable that the door 10 closes more slowly after time T1 than before.

[0079] During the period from time T2 to time T3, the opening width of the door 10 is very small, so there is no possibility of the door 10 contacting a person's head while closing, but there is a possibility of it contacting a person's fingers. The impact resistance of the door 10 from contact is weaker for fingers than for the head. Therefore, it is preferable that the door 10 closes more slowly after time T2 than before. Accordingly, as shown in Figures 4A and 4B, the increase in the displacement amount A of the door 10 becomes gradual over time.

[0080] As explained using Figure 3, after time T0, the first chamber pressure P1 rises from atmospheric pressure Po. The second chamber pressure P2 decreases from value P2x. As described above, at time T1, the movement speed of the moving body 14b decreases due to the switching of the flow control valve. Similarly, at time T2, the movement speed of the moving body 14b decreases further due to further switching of the flow control valve.

[0081] At time T3, the moving body 14b reaches the terminal position described above. In this case, the door 10 stops, and the displacement A becomes constant at value A3. At time T3, since the moving body 14b stops at the terminal position, the second room pressure P2 then decreases to atmospheric pressure Po.

[0082] Figure 4A shows an example where the fluid pressure of the drive fluid is not reduced by the first pressure reducing valve 30pa and the second pressure reducing valve 30pb. In this case, at time T1, the moving speed of the moving body 14b decreases, causing both the first chamber pressure P1 and the second chamber pressure P2 to rise. Furthermore, at time T2, the moving speed of the moving body 14b decreases further, causing both the first chamber pressure P1 and the second chamber pressure P2 to rise even more.

[0083] The difference G mentioned above is the difference between the second chamber pressure P2, which is higher than the predetermined pressure Pt, and the predetermined pressure Pt. As shown in Figure 4A, the value of the difference G in the time period before time T1 is G1. The value of the difference G in the time period before time T2 is G2, which is greater than G1. The value of the difference G in the time period before time T3 is G3, which is even greater than G2. In other words, as the movement speed of the moving body 14b decreases, the second chamber pressure P2 increases, and the difference G increases. A smaller difference G means that the time required from when the door 10 contacts the obstacle J until the second chamber pressure P2 falls below the predetermined pressure Pt is shorter. Therefore, the response time Te mentioned above is also shortened.

[0084] Figure 4B shows an example where the fluid pressure of the drive fluid is reduced by the first pressure reducing valve 30pa and the second pressure reducing valve 30pb. In this case, as shown in Figure 4B, the increase in the first chamber pressure P1 and the second chamber pressure P2 due to the decrease in the moving speed of the moving body 14b is suppressed compared to the example shown in Figure 4A. Therefore, the increase in the difference G between the second chamber pressure P2, which is higher than the predetermined pressure Pt, and the predetermined pressure Pt is also suppressed.

[0085] Suppose that just before time T1, after a predetermined time Tq1 has elapsed from time T0, the partially closing door 10 comes into contact with the torso of a person, which is an obstacle J. In that case, a response time Te corresponding to the difference G value G1 is required before the door 10 begins to open again.

[0086] Suppose that a door 10, which is in the process of closing, comes into contact with an obstacle J, which is the head of a person, after a predetermined time Tq2 has elapsed from time T0, or just before time T2, which is after a predetermined time Tq2-Tq1 has elapsed from time T1. In that case, a response time Te corresponding to the difference G value G2 is required before the door 10 begins to open again.

[0087] Suppose that just before door 10 reaches closing time T3, the closing door 10 comes into contact with a human hand, which is an obstacle J. In that case, a response time Te corresponding to the difference G value G3 is required before door 10 begins to open again.

[0088] Compared to Figure 4A, there is no significant difference in the difference G values ​​G1, G2, and G3 shown in Figure 4B. In other words, the increase in difference G is suppressed in response to the decrease in the moving speed of the moving body 14b. Therefore, the response time Te can be shortened, and thus safety is improved.

[0089] When the driving fluid is supplied to the first chamber R1, the moving body 14b reaches the aforementioned terminal position at time T3. In this case, the pressure P2 in the second chamber remains higher than the predetermined pressure Pt from the time the moving body 14b starts moving until it reaches the terminal position. Also, since the moving body 14b stops at the terminal position at time T3, the pressure P2 in the second chamber gradually decreases and drops to atmospheric pressure Po, which is lower than the predetermined pressure Pt. The opening degree of the pressure regulating valve 38 is set so that the predetermined pressure Pt satisfies these conditions. As a result, the switching control unit 36 ​​can switch the flow path through which the driving fluid flows into the flow path switching unit 34 at an appropriate timing.

[0090] Figure 5 illustrates the fluid supply control device 12 in the process of closing the door 10. Figure 5 shows the state from time T0 to time T1 while the door 10 is in the process of closing. At time T0, the door 10 changes from the open state shown in Figure 1 to the state for closing the door 10 as shown in Figure 5. Figure 1 shows the state in which the drive fluid is supplied to the second chamber R2 and the first discharge fluid is discharged from the first chamber R1. Figure 5 shows the state in which the drive fluid is supplied to the first chamber R1 and the second discharge fluid is discharged from the second chamber R2. The change from the state shown in Figure 1 to the state shown in Figure 5 will be explained below.

[0091] First, the flow path within the fluid supply valve 16 is switched by electromagnetic control. As a result, the atmospheric pressure Po and the supply pressure of the drive fluid applied to the directional control valve 34a of the flow path switching unit 34 are reversed. Specifically, in Figure 1, atmospheric pressure Po is applied to the directional control valve 34a from the left (as viewed from the plane of the paper), and the supply pressure of the drive fluid is applied from the right (as viewed from the plane of the paper). In Figure 5, the supply pressure of the drive fluid is applied to the directional control valve 34a from the left (as viewed from the plane of the paper), and atmospheric pressure Po is applied from the right (as viewed from the plane of the paper). The supply pressure of the drive fluid is higher than the atmospheric pressure Po. Therefore, the flow path within the directional control valve 34a is also switched.

[0092] Furthermore, the atmospheric pressure Po and the supply pressure of the drive fluid applied to the directional control valve 34b of the flow path switching unit 34 are in opposite directions. Specifically, in Figure 1, atmospheric pressure Po is applied to the directional control valve 34b from the left, and the supply pressure of the drive fluid is applied from the right. In Figure 5, the supply pressure of the drive fluid is applied to the directional control valve 34b from the left, and atmospheric pressure Po is applied from the right. The supply pressure of the drive fluid applied to the directional control valve 34b from the left is transmitted from the directional control valve 36b of the switching control unit 36.

[0093] Because the pressure applied to the directional control valve 34b from the left and right sides is reversed, the flow path within the directional control valve 34b is also switched. Therefore, the flow path switching unit 34 causes the drive fluid from the fluid supply valve 16 to flow into the first fluid control unit 30.

[0094] In Figure 1, the first discharge fluid discharged from the first chamber R1 flows through the first fluid control unit 30. In Figure 5, the drive fluid supplied to the first chamber R1 flows through the first fluid control unit 30. In both Figure 1 and Figure 5, the fluid flows along the first path U1 within the first fluid control unit 30. However, in the first fluid control unit 30 shown in Figure 1 and Figure 5, the direction in which the fluid flows along the first path U1 is opposite to that of the first fluid control unit 30 shown in Figure 1 and Figure 5.

[0095] In Figure 1, the drive fluid supplied to the second chamber R2 flows through the second fluid control unit 32. In Figure 5, the second discharge fluid discharged from the second chamber R2 flows through the second fluid control unit 32. In both Figure 1 and Figure 5, the fluid flows along the first path V1 within the second fluid control unit 32. However, in the second fluid control unit 32 shown in Figures 1 and 5, the direction in which the fluid flows along the first path V1 is opposite to that of the second fluid control unit 32 shown in Figures 1 and 5.

[0096] Furthermore, by switching the fluid supply valve 16 and the directional control valve 34a of the flow path switching unit 34, a portion of the driving fluid begins to be supplied to the fluid timer 42 via the switching control unit 36. Specifically, in Figure 5, the supply pressure of the driving fluid is applied to the directional control valve 36b of the switching control unit 36 ​​from the left, and atmospheric pressure Po is applied from the right. As a result, a portion of the driving fluid is supplied to the fluid timer 42 via the directional control valve 36b. As the fluid timer 42 begins to store fluid in the tank 42t, the pressure inside the tank 42t begins to rise.

[0097] Furthermore, as described above, the directional control valve 36b through which a portion of the driving fluid flows transmits the supply pressure of the driving fluid to the directional control valve 34b of the flow path switching unit 34.

[0098] Figure 6 illustrates the fluid supply control device 12 in the process of closing the door 10. Figure 6 shows the state from time T1 to time T2 while the door 10 is in the process of closing. At time T1, the state changes from the state shown in Figure 5 to the state shown in Figure 6. Figure 5 shows the state in which the flow rate of the second discharge fluid is restricted by the first flow control valve 32fa. Figure 6 shows the state in which the flow rate of the second discharge fluid is restricted by the second flow control valve 32fb. The change from the state shown in Figure 5 to the state shown in Figure 6 will be explained below.

[0099] In Figure 5, the first flow control switching valve 32da of the second fluid control unit 32 causes the second discharge fluid to flow into the first flow control valve 32fa. The second discharge fluid, whose flow rate is restricted by the first flow control valve 32fa, flows along the first path V1. The directional control valve 30da of the first fluid control unit 30 supplies the drive fluid to the first chamber R1 via the directional control valve 30db, without passing it through the first pressure reducing valve 30pa. The drive fluid flows along the first path U1.

[0100] In Figure 5, atmospheric pressure Po is applied to the first flow control switching valve 32da of the second fluid control unit 32 from the left (as viewed from the plane of the paper), and the pressure inside the tank 42t of the fluid timer 42A is applied from the right (as viewed from the plane of the paper). In Figure 5, atmospheric pressure Po is applied to the directional control valve 30da of the first fluid control unit 30 from the left, and the pressure inside the tank 42t of the fluid timer 42A is applied from the right.

[0101] As described above, the pressure in the tank 42t of the fluid timer 42 shown in Figure 5 is rising. The pressure in the tank 42t of fluid timer 42A rises faster than the pressure in the tank 42t of fluid timer 42B. At time T1, the pressure in the tank 42t of fluid timer 42A reaches a predetermined operating pressure value Pa. The predetermined operating pressure value Pa is higher than atmospheric pressure Po.

[0102] Therefore, switching of the flow path in the first flow control switching valve 32da of the second fluid control unit 32 and switching of the flow path in the directional control valve 30da of the first fluid control unit 30 occur. The first flow control switching valve 32da of the second fluid control unit 32 and the directional control valve 30da of the first fluid control unit 30 after these switching has occurred are shown in Figure 6.

[0103] As shown in Figure 6, the first flow control valve 32da of the second fluid control unit 32 switches the flow path, causing the first flow control valve 32da to output the second discharge fluid to the second flow control valve 32db. The second flow control valve 32db then causes the second discharge fluid to flow into the second flow control valve 32fb. In other words, the path through which the second discharge fluid flows is switched from the first path V1 to the second path V2. The flow control valve that limits the flow rate of the second discharge fluid is switched from the first flow control valve 32fa to the second flow control valve 32fb. This switching reduces the flow rate of the second discharge fluid.

[0104] As shown in Figure 6, by switching the flow path within the directional control valve 30da of the first fluid control unit 30, the path through which the drive fluid flows is switched from the first path U1 to the second path U2. The directional control valve 30da of the first fluid control unit 30 supplies the drive fluid to the first chamber R1 via the directional control valve 30db, passing it through the first pressure reducing valve 30pa. The drive fluid is reduced in pressure by the first pressure reducing valve 30pa before being supplied to the first chamber R1.

[0105] Figure 7 illustrates the fluid supply control device 12 in the process of closing the door 10. Figure 7 shows the state from time T2 to time T3 while the door 10 is in the process of closing. At time T2, the state changes from the state shown in Figure 6 to the state shown in Figure 7. Figure 6 shows the state in which the flow rate of the second discharge fluid is restricted by the second flow control valve 32fb. Figure 7 shows the state in which the flow rate of the second discharge fluid is restricted by the third flow control valve 32fc. The change from the state shown in Figure 6 to the state shown in Figure 7 will be explained below.

[0106] In Figure 6, the second flow control switching valve 32db of the second fluid control unit 32 allows the second discharge fluid to flow into the second flow control valve 32fb, as described above. The second discharge fluid, whose flow rate is restricted by the second flow control valve 32fb, flows along the second path V2. The driving fluid is depressurized by the first pressure reducing valve 30pa before flowing into the directional control valve 30db of the first fluid control unit 30. The directional control valve 30db supplies the driving fluid to the first chamber R1 without passing it through the second pressure reducing valve 30pb. The driving fluid flows along the second path U2.

[0107] In Figure 6, atmospheric pressure Po is applied to the second flow control switching valve 32db of the second fluid control unit 32 from the left (as viewed from the plane of the paper), and the pressure inside the tank 42t of the fluid timer 42B is applied from the right (as viewed from the plane of the paper). In Figure 6, atmospheric pressure Po is applied to the directional control valve 30db of the first fluid control unit 30 from the left, and the pressure inside the tank 42t of the fluid timer 42B is applied from the right.

[0108] As described above, the pressure inside the tank 42t of the fluid timer 42B shown in Figure 6 is rising. At time T2, the pressure inside the tank 42t of the fluid timer 42B reaches a predetermined operating pressure value Pb. The predetermined operating pressure value Pb is higher than atmospheric pressure Po.

[0109] Therefore, switching of the flow path in the second flow control switching valve 32db of the second fluid control unit 32 and switching of the flow path in the directional control valve 30db of the first fluid control unit 30 occur. The second flow control switching valve 32db of the second fluid control unit 32 and the directional control valve 30db of the first fluid control unit 30 after these switching has occurred are shown in Figure 7.

[0110] As shown in Figure 7, the second flow control valve 32db of the second fluid control unit 32 switches the flow path, causing the second discharge fluid to flow into the third flow control valve 32fc. In other words, the path through which the second discharge fluid flows is switched from the second path V2 to the third path V3. The flow control valve that limits the flow rate of the second discharge fluid is switched from the second flow control valve 32fb to the third flow control valve 32fc. This switching reduces the flow rate of the second discharge fluid.

[0111] As shown in Figure 7, by switching the flow path within the directional control valve 30db of the first fluid control unit 30, the path through which the drive fluid flows is switched from the second path U2 to the third path U3. The directional control valve 30db of the first fluid control unit 30 supplies the drive fluid to the first chamber R1 via the second pressure reducing valve 30pb, without passing it through either the first pressure reducing valve 30pa or the directional control valve 30da. The drive fluid is reduced in pressure by the second pressure reducing valve 30pb before being supplied to the first chamber R1. As described above, the fluid pressure of the drive fluid reduced in pressure by the second pressure reducing valve 30pb is lower than the fluid pressure of the drive fluid reduced in pressure by the first pressure reducing valve 30pa.

[0112] Figure 8 illustrates the fluid supply control device 12 at time T3 when the door 10 is closed and thereafter. The moving body 14b, which was moving in direction D due to the supply of driving fluid to the first chamber R1, reaches the aforementioned terminal position at time T3. As a result, the door 10 closes. In this case, the state changes from the state shown in Figure 7 to the state shown in Figure 8. The change from the state shown in Figure 7 to the state shown in Figure 8 will be explained below.

[0113] In Figure 7, atmospheric pressure Po is applied to the switching suppression unit 40, which is a directional control valve, from the left side of the page. In this case, a predetermined pressure Pt is transmitted from the switching suppression unit 40 to the switching control unit 36, similar to the example shown in Figure 1. Specifically, the switching suppression unit 40 transmits the predetermined pressure Pt, adjusted by the pressure regulating valve 38, to the directional control valve 36a of the switching control unit 36.

[0114] In Figure 7, the second chamber pressure P2 is applied to the directional control valve 36a of the switching control unit 36 ​​from the left, and a predetermined pressure Pt is applied from the right. As explained using Figure 4B, until before time T3, the second chamber pressure P2 is higher than the predetermined pressure Pt. In that case, as shown in Figure 7, atmospheric pressure Po is transmitted from the directional control valve 36a to the directional control valve 36b. Therefore, in Figure 7, atmospheric pressure Po is applied to the directional control valve 36b from the left, and atmospheric pressure Po is also applied from the right. The state of the directional control valve 36b shown in Figure 7 has not changed from the state of the directional control valve 36b shown in Figure 5.

[0115] Before time T3, the limit valve 18 transmits atmospheric pressure Po to the switching suppression unit 40, as shown in Figure 7. At time T3, the closed door 10 comes into contact with the limit valve 18, as shown in Figure 8. This causes the limit valve 18 to switch. After time T3, the limit valve 18 transmits the supply pressure of the drive fluid to the switching suppression unit 40, as shown in Figure 8.

[0116] When the atmospheric pressure Po transmitted to the switching suppression unit 40 is switched to the supply pressure of the drive fluid, the switching suppression unit 40 switches its internal flow path. As a result, the switching suppression unit 40 blocks the transmission of a predetermined pressure Pt from the switching control unit 36 ​​to the directional control valve 36a. The switching suppression unit 40 then transmits the atmospheric pressure Po to the directional control valve 36a.

[0117] In Figure 8, the second chamber pressure P2 is applied to the directional control valve 36a of the switching control unit 36 ​​from the left, and atmospheric pressure Po is applied from the right. As explained using Figure 4B, as the moving body 14b reaches its terminal position, the second chamber pressure P2 of the actuator 14 decreases to atmospheric pressure Po. The second chamber pressure P2 never falls below atmospheric pressure Po. Therefore, even when the second chamber pressure P2 decreases, the directional control valve 36a does not switch its internal flow path.

[0118] Therefore, the directional control valve 36a of the switching control unit 36 ​​transmits atmospheric pressure Po to the directional control valve 36b of the switching control unit 36. In Figure 8, atmospheric pressure Po is applied to the directional control valve 36b from both the left and the right. The state of the directional control valve 36b shown in Figure 8 is the same as the state of the directional control valve 36b shown in Figure 7. As a result, the switching of the flow path for the driving fluid by the flow path switching unit 34, which may occur when the second chamber pressure P2 falls below a predetermined pressure Pt, is suppressed.

[0119] In other words, the switching suppression unit 40 suppresses the switching of the flow path into which the driving fluid flows by the flow path switching unit 34. The switching of this flow path will be described later with reference to Figure 9.

[0120] Figure 9 illustrates the fluid supply control device 12 when the door 10 stops while closing. As shown in Figures 5 to 7, the door 10 comes into contact with an obstacle J while closing, as shown in Figure 9. As described above using Figure 3, when the door 10 comes into contact with an obstacle J while the door 10 is closing, the pressure P2 in the second chamber becomes lower than a predetermined pressure Pt. The pressure P2 in the second chamber is transmitted to the directional control valve 36a of the switching control unit 36 ​​by the second discharge fluid. The predetermined pressure Pt is transmitted to the directional control valve 36a of the switching control unit 36 ​​after the supply pressure of the drive fluid is adjusted by the pressure regulating valve 38.

[0121] In that case, the directional control valve 36a of the switching control unit 36 ​​shown in Figures 5 to 7 switches the internal flow path. The switching of this directional control valve 36a, the switching of the directional control valve 36b of the switching control unit 36 ​​that accompanies this switching, and the switching of the directional control valve 34b of the flow path switching unit 34 that accompanies this switching are shown in Figure 9.

[0122] Specifically, the directional control valve 36a of the switching control unit 36 ​​transmits the supply pressure of the drive fluid to the directional control valve 36b of the switching control unit 36 ​​by switching its internal flow path. In Figure 9, atmospheric pressure Po is applied to the directional control valve 36b from the left (as viewed from the plane of the paper), and the supply pressure of the drive fluid is applied from the right (as viewed from the plane of the paper). As a result, the directional control valve 36b of the switching control unit 36 ​​switches its internal flow path to transmit the supply pressure of the drive fluid to the directional control valve 34b of the flow path switching unit 34.

[0123] In Figures 5 to 7, the supply pressure of the driving fluid is applied to the directional control valve 34b of the flow path switching section 34 from the left (towards the plane of the paper), and atmospheric pressure Po is applied from the right (towards the plane of the paper). The directional control valve 34b supplies the driving fluid to the first fluid control unit 30. Due to the switching of the flow path within the directional control valve 36b of the switching control unit 36 ​​described above, the pressure applied to the directional control valve 34b of the flow path switching section 34 from the left and right is reversed. That is, in Figure 9, atmospheric pressure Po is applied to the directional control valve 34b from the left (towards the plane of the paper), and the supply pressure of the driving fluid is applied from the right (towards the plane of the paper). The directional control valve 34b of the flow path switching section 34 switches the internal flow path.

[0124] As a result, the directional control valve 34b switches the flow path for the drive fluid from the flow path connected to the first fluid control unit 30 to the flow path connected to the second fluid control unit 32. In this way, the switching control unit 36 ​​causes the flow path switching unit 34 to switch the flow path for the drive fluid. The drive fluid is supplied to the second chamber R2 via the second fluid control unit 32. The first discharge fluid is discharged from the first chamber R1.

[0125] Therefore, the moving body 14b, which was moving in the direction D to close the door 10, not only stops but also moves in the direction E, causing the door 10 to open. This ensures safety in the event that the door 10 comes into contact with an obstacle J.

[0126] As described above using Figure 8, when the moving body 14b reaches the terminal position, the switching suppression unit 40 transmits atmospheric pressure Po to the directional control valve 36a of the switching control unit 36. Even if the pressure P2 in the second chamber decreases in response to the moving body 14b reaching the terminal position, the directional control valve 36a does not switch the internal flow path.

[0127] In other words, the switching suppression unit 40 blocks the transmission of a predetermined pressure Pt from the switching control unit 36 ​​to the directional control valve 36a. As a result, the switching suppression unit 40 suppresses the switching of the flow path through which the drive fluid flows in by the flow path switching unit 34. Therefore, when the door 10 stops by closing, unlike when the door 10 stops by contacting an obstacle J, the door 10 does not open. This prevents the door 10 from moving in the opposite direction E even though it is not in contact with an obstacle J while moving in direction D.

[0128] In the above-described embodiment, when the movable body 14b reaches the end position of its range of motion, the limit valve 18 switches. However, a position sensor for detecting the position of the movable body 14b may be provided in the cylinder described above. For example, a magnet may be attached to the movable body 14b, and a magnetic sensor may be used as the position sensor.

[0129] In that case, a position sensor (not shown) detects that the moving body 14b has reached its terminal position and transmits a sensor signal to a valve switching control device (not shown). Based on the sensor signal, the valve switching control device controls the switching suppression unit 40 by switching the flow path inside the directional control valve (not shown). Based on the control by the valve switching control device, the switching suppression unit 40 blocks the transmission of a predetermined pressure Pt from the switching control unit 36 ​​to the directional control valve 36a. The switching suppression unit 40 transmits atmospheric pressure Po to the directional control valve 36a.

[0130] Furthermore, in the above-described embodiment, a fluid timer 42 is used. As a result, after predetermined times Tq1 and Tq2 have elapsed since the start of limiting the flow rate of the second discharge fluid, a switch in the direction of fluid flow occurs between the first fluid control unit 30 and the second fluid control unit 32. However, a valve switching control device (not shown) may measure the predetermined times Tq1 and Tq2 using a timer circuit or the like. After the predetermined times Tq1 and Tq2 have elapsed, the valve switching control device switches the flow path inside a directional control valve (not shown) to switch the direction of fluid flow between the first fluid control unit 30 and the second fluid control unit 32.

[0131] With regard to the embodiments described above, the following additional information is disclosed.

[0132] (Note 1) The fluid supply control device (12) of the present disclosure is a fluid supply control device that controls the supply of drive fluid to an actuator (14) which has a movable body (14b) inside which is movable by the supply of drive fluid from a fluid supply valve (16), and moves a door (10) of a machine tool by the movement of the movable body, and comprises a first fluid control unit (30) into which the incoming drive fluid is supplied to a first chamber (R1) in the actuator, or into which a first discharge fluid discharged from the first chamber is supplied, and a second fluid control unit (32) into which a second discharge fluid discharged from a second chamber (R2) in the actuator, which is adjacent to the first chamber and separated from the movable body, is supplied, or into which the incoming drive fluid is supplied. The system includes a flow path switching unit (34) to which a flow path is connected to the first fluid control unit and the second fluid control unit, respectively, and which switches the flow path to allow the drive fluid from the fluid supply valve to flow into either the first fluid control unit or the second fluid control unit; and a switching control unit (36) which, when the second chamber pressure (P2) in the second chamber falls below a predetermined pressure (Pt) while the drive fluid is being supplied to the first chamber, transmits the supply pressure of the drive fluid to the flow path switching unit, causing the flow path switching unit to switch the flow path from the flow path connected to the first fluid control unit to the flow path connected to the second fluid control unit to allow the drive fluid to flow in. With this configuration, safety is improved when the door of the machine tool comes into contact with an obstacle.

[0133] (Note 2) In the fluid supply control device described in Note 1, the second fluid control unit may have a first flow control valve (32fa) that limits the flow rate of the second discharge fluid discharged from the second chamber and flowing in when the drive fluid is supplied to the first chamber. With such a configuration, the moving speed of the moving body can be limited.

[0134] (Note 3) A fluid supply control device as described in Note 2, wherein the first fluid control unit has a pressure reducing valve (30pa) that reduces the fluid pressure of the incoming drive fluid when the drive fluid is supplied to the first chamber, and the second fluid control unit has a second flow control valve (32fb) different from the first flow control valve that limits the flow rate of the incoming second discharge fluid when the drive fluid is supplied to the first chamber, and a flow control switching valve (32da) that switches the flow control valve that allows the second discharge fluid to flow in from the first flow control valve to the second flow control valve after a predetermined time (Tq1) has elapsed since the first flow control valve started limiting the flow rate of the second discharge fluid, and the first fluid control unit may, after the predetermined time has elapsed, reduce the pressure of the drive fluid via the pressure reducing valve before allowing it to flow into the first fluid control unit. With such a configuration, safety is further improved.

[0135] (Note 4) In the fluid supply control device described in Note 3, the opening degrees of the first flow control valve and the second flow control valve may be set in advance so that the flow rate of the second discharge fluid restricted by the second flow control valve is less than the flow rate of the second discharge fluid restricted by the first flow control valve. With such a configuration, the speed of the machine tool door can be slowed down.

[0136] (Note 5) The fluid supply control device described in Note 1 further comprises a pressure regulating valve (38) for adjusting the supply pressure of the drive fluid to a predetermined pressure, and when the drive fluid is supplied to the first chamber, if the pressure inside the second chamber transmitted to the switching control unit by the second discharge fluid discharged from the second chamber becomes lower than the predetermined pressure transmitted to the switching control unit after the supply pressure of the drive fluid is adjusted by the pressure regulating valve, the switching control unit may cause the flow path switching unit to switch the flow path. With such a configuration, safety is ensured when the door of the machine tool comes into contact with an obstacle.

[0137] (Note 6) In the fluid supply control device described in Note 5, the opening degree of the pressure regulating valve may be set such that when the moving body reaches the end position of the moving range due to the supply of the driving fluid to the first chamber, the pressure in the second chamber becomes higher than the predetermined pressure until the moving body reaches the end position, and when the moving body stops before the end position, the pressure in the second chamber becomes lower than the predetermined pressure. With such a configuration, the flow path into which the driving fluid flows into the flow path switching section can be switched at an appropriate timing.

[0138] (Note 7) The fluid supply control device described in Note 6 may further include a switching suppression unit (40) that suppresses the switching of the flow path by the flow path switching unit by blocking the transmission of the predetermined pressure to the switching control unit by the pressure regulating valve when the moving body reaches the terminal position. With such a configuration, the switching of the flow path into which the driving fluid flows by the flow path switching unit is not required, and the switching can be suppressed.

[0139] While this disclosure has been described in detail, it is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of this disclosure or from the spirit of this disclosure derived from the claims and their equivalents. These embodiments can also be implemented in combination. For example, the order of operations and processes in the embodiments described above are given as examples only and are not limited thereto. The same applies when numerical values ​​or mathematical formulas are used in the description of the embodiments described above.

[0140] 10...Door 12...Fluid supply control device 14...Actuator 16...Fluid supply valve 18...Limit valve 30...First fluid control unit 32...Second fluid control unit 34...Flow path switching unit 36...Switching control unit 38...Pressure regulating valve 40...Switching suppression unit 42...Fluid timer 44...Shuttle valve 46...Exhaust device

Claims

1. A fluid supply control device (12) for controlling the supply of drive fluid to an actuator (14) which has a movable body (14b) inside that is movable by the supply of drive fluid from a fluid supply valve (16), and which moves a door (10) of a machine tool by the movement of the movable body, comprising: a first fluid control unit (30) which supplies the incoming drive fluid to a first chamber (R1) in the actuator, or into which a first discharge fluid discharged from the first chamber flows; a second fluid control unit (32) which receives a second discharge fluid discharged from a second chamber (R2) adjacent to the first chamber and the movable body in the actuator, or which supplies the incoming drive fluid to the second chamber; a flow path switching unit (34) which has flow paths connected to the first fluid control unit and the second fluid control unit, respectively, and which switches the flow paths to allow the drive fluid from the fluid supply valve to flow into either the first fluid control unit or the second fluid control unit, A fluid supply control device comprising: a switching control unit (36) that, when the driving fluid is supplied to the first chamber, and the second chamber pressure (P2) in the second chamber falls below a predetermined pressure (Pt), transmits the supply pressure of the driving fluid to the flow path switching unit, thereby causing the flow path switching unit to switch the flow path that allows the driving fluid to flow from the flow path connected to the first fluid control unit to the flow path connected to the second fluid control unit; 2. A fluid supply control device according to claim 1, wherein the second fluid control unit has a first flow control valve (32fa) that limits the flow rate of the second discharge fluid discharged from the second chamber and flowing in when the drive fluid is supplied to the first chamber.

3. A fluid supply control device according to claim 2, wherein the first fluid control unit has a pressure reducing valve (30pa) for reducing the fluid pressure of the incoming drive fluid when the drive fluid is supplied to the first chamber, and the second fluid control unit has a second flow control valve (32fb) different from the first flow control valve for limiting the flow rate of the incoming second discharge fluid when the drive fluid is supplied to the first chamber, and a flow control switching valve (32da) for switching the flow control valve that allows the second discharge fluid to flow in from the first flow control valve to the second flow control valve after a predetermined time (Tq1) has elapsed since the first flow control valve started limiting the flow rate of the second discharge fluid, and the first fluid control unit, after the predetermined time has elapsed, reduces the pressure of the drive fluid via the pressure reducing valve before allowing it to flow into the first fluid control unit.

4. A fluid supply control device according to claim 3, wherein the opening degrees of the first flow control valve and the second flow control valve are set in advance so that the flow rate of the second discharge fluid restricted by the second flow control valve is less than the flow rate of the second discharge fluid restricted by the first flow control valve.

5. A fluid supply control device according to claim 1, further comprising a pressure regulating valve (38) for adjusting the supply pressure of the drive fluid to a predetermined pressure, wherein, when the drive fluid is supplied to the first chamber, the pressure in the second chamber transmitted to the switching control unit by the second discharge fluid discharged from the second chamber becomes lower than the predetermined pressure transmitted to the switching control unit after the supply pressure of the drive fluid is adjusted by the pressure regulating valve, the switching control unit causes the flow path switching unit to switch the flow path.

6. A fluid supply control device according to claim 5, wherein the opening of the pressure regulating valve is set such that when the moving body reaches the end position of the moving range of the moving body due to the supply of the driving fluid to the first chamber, the pressure in the second chamber becomes higher than the predetermined pressure until the moving body reaches the end position, and when the moving body stops before the end position, the pressure in the second chamber becomes lower than the predetermined pressure.

7. A fluid supply control device according to claim 6, further comprising a switching suppression unit (40) that suppresses the switching of the flow path by the flow path switching unit by blocking the transmission of the predetermined pressure to the switching control unit by the pressure regulating valve when the moving body reaches the terminal position.

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