Pilot cap unit

Abstract

To prevent malfunction of an unused control valve.SOLUTION: A first pilot cap 40 of a pilot cap unit 100 includes a valve element storage hole 55 which can store a part of a solenoid proportional pressure reducing valve 7a for controlling pressure of pilot fluid supplied to a first pilot chamber 11a, a pilot passage 47 which communicates with the valve element storage hole 55 and guides the pilot fluid decompressed by the solenoid proportional pressure reducing valve 7a to the first pilot chamber 11a, and a cap side drain passage 49 which communicates with the valve element storage hole 55 and to which the pilot fluid delivered from the solenoid proportional pressure reducing valve 7a is guided. The solenoid proportional pressure reducing valve 7a can be attached to the valve element storage hole 55, and the solenoid proportional pressure reducing valve 7a can be replaced with a plug 58. In a state where the plug 58 is attached to the valve element storage hole 55, the pilot passage 47 and the cap side drain passage 49 always communicate with each other through a plug passage 58e formed in the plug 58.SELECTED DRAWING: Figure 5

Description

Technical Field

[0006] , , ,

[0005] , , ,

[0001] The present invention relates to a pilot cap unit.

Background Art

[0002] Patent Document 1 discloses a control valve provided with a cap. The cap includes a pilot cap that is attached to a valve housing in which a spool is incorporated and defines a pilot chamber together with the valve housing, and a solenoid valve that is attached to the pilot cap and controls the pressure of the working fluid supplied to the pilot chamber.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the control valve described in Patent Document 1, depending on the user's method of use, some control valves may be left unused. In the control valve described in Patent Document 1, there is a risk that the working fluid discharged from the pump leaks into the unused pilot chamber through the inner peripheral surface of the sliding hole where the unused spool slides and the outer peripheral surface of the unused spool. In this case, the unused spool may move, causing the unused control valve to malfunction.

[0005] The present invention has been made in view of the above problems, and an object thereof is to prevent malfunction of an unused control valve.

Means for Solving the Problems

[0006] The present invention relates to a pilot cap unit to be attached to a control valve having a valve housing formed through which a spool hole is formed, through which a spool is slidably housed, and comprises a first pilot cap attached to the valve housing so as to face one end of the spool hole and partitioning a first pilot chamber between itself and the valve housing, wherein the first pilot cap has a housing hole capable of housing a part of a solenoid valve that controls the pressure of pilot fluid supplied to the first pilot chamber, a pilot passage communicating with the housing hole and guiding the pilot fluid, which has been depressurized by the solenoid valve, to the first pilot chamber, and a drain passage communicating with the housing hole and guiding the pilot fluid discharged from the solenoid valve, wherein a solenoid valve can be attached to the housing hole, and a plug can be attached in place of the solenoid valve, and when a plug is attached to the housing hole, the pilot passage and the drain passage are always in communication through a plug passage formed in the plug.

[0007] In this invention, when a plug is installed in place of a solenoid valve in the housing hole, the first pilot chamber is always connected to the drain passage through the pilot passage and the plug passage. Therefore, even if working fluid leaks into the first pilot chamber, the pressure inside the first pilot chamber is prevented from rising. Thus, even if working fluid leaks into the pilot chamber of an unused control valve, the plug prevents the spool from moving due to the pressure of the leaked working fluid. Therefore, malfunction of the unused control valve is prevented.

[0008] Furthermore, the present invention further comprises a second pilot cap attached to the valve housing so as to face the other end of the spool hole and partitioning a second pilot chamber between itself and the valve housing, wherein the valve housing has a first port that opens into the spool hole and is provided adjacent to the second pilot chamber and communicates with the atmosphere, and a second port that opens into the spool hole and is provided adjacent to the first pilot chamber and has a higher pressure than the first port, and a plug can be attached to the first pilot cap in place of a solenoid valve.

[0009] In this invention, the second pilot chamber is adjacent to a first port that communicates with the atmosphere, and the first pilot chamber is adjacent to a second port that has a higher pressure than the first port. Because the first port communicates with the atmosphere, pressure is less likely to build up in the second pilot chamber, but because the second port has a higher pressure than the first port, pressure is more likely to build up in the first pilot chamber than in the second pilot chamber. Therefore, if working fluid leaks through the space between the inner surface of the spool hole and the outer surface of the spool, pressure is more likely to build up in the first pilot chamber than in the second pilot chamber. However, the movement of the spool due to the pressure in the first pilot chamber can be prevented by a plug. [Effects of the Invention]

[0010] According to the present invention, malfunctions of unused control valves are prevented. [Brief explanation of the drawing]

[0011] [Figure 1] This is a fluid pressure circuit diagram of a fluid pressure control device including a control valve. [Figure 2] This is a plan view of the first pilot cap of a pilot cap unit according to an embodiment of the present invention. [Figure 3] This is a side view of the first pilot cap as seen from direction III in Figure 2. [Figure 4] This is a cross-sectional view showing a pilot cap unit and a control valve according to an embodiment of the present invention. [Figure 5] This is an enlarged cross-sectional view showing the plug attached to the first pilot cap. [Modes for carrying out the invention]

[0012] With reference to the drawings, a first pilot cap unit 100a and a second pilot cap unit 100b according to embodiments of the present invention will be described. Hereinafter, the first pilot cap unit 100a and the second pilot cap unit 100b will be collectively referred to simply as "pilot cap unit 100".

[0013] The pilot cap unit 100 and the control valve 10 equipped therewith are provided in the fluid pressure control device 1. The fluid pressure control device 1 is a device that controls actuators driven by working fluid discharged from a pump, and is mounted on work machines such as construction machines, agricultural machines, and industrial machines. The following describes a case in which the fluid pressure control device 1 is mounted on a hydraulic excavator and used to control the operation of actuators such as the hydraulic motor for travel and hydraulic cylinders for driving booms, arms, buckets, etc. Although the example described uses hydraulic oil as the working fluid for driving the actuators of a hydraulic excavator, other fluids such as working water may also be used as the working fluid.

[0014] First, the hydraulic circuit of the fluid pressure control device 1 will be described with reference to Figure 1. The fluid pressure control device 1 includes a hydraulic pump 3, a hydraulic cylinder 6 as an actuator driven by the hydraulic fluid discharged from the hydraulic pump 3, a supply passage 20 for supplying the hydraulic fluid discharged from the hydraulic pump 3, and a control valve 10 provided in the supply passage 20 for controlling the flow of hydraulic fluid supplied to and discharged from the hydraulic cylinder 6. Multiple hydraulic cylinders 6 and control valves 10 are provided, and Figure 1 shows one hydraulic cylinder 6 and two control valves 10 as representative examples.

[0015] The hydraulic pump 3 is driven by an engine mounted on the hydraulic excavator. The hydraulic pump 3 may also be driven by an electric motor. The hydraulic fluid discharged from the hydraulic pump 3 is led to the control valve 10 through a supply passage 20. Hydraulic fluid is supplied to and discharged from the rod side chamber 6a and bottom side chamber 6b of the hydraulic cylinder 6 through a pair of actuator passages 21. Depending on the position of the control valve 10, one of the pair of actuator passages 21 is connected to the supply passage 20, and the other is connected to a tank passage 22 that communicates with the tank 4.

[0016] The control valve 10 is a 4-port, 3-position spool valve, and in this embodiment, multiple control valves 10 with the same configuration are provided corresponding to each hydraulic cylinder 6. The control valve 10 switches positions when pilot pressure is introduced to a pair of pilot chambers 11 through a pilot passage 16 according to the direction and amount of operation of the operating lever 9 by the operator. The control valve 10 switches positions between a neutral position 10A, an extended position 10B, and a retracted position 10C depending on the magnitude of the pilot pressure supplied to the pair of pilot chambers 11.

[0017] Specifically, the pilot passage 16 is provided with an electromagnetic proportional pressure reducing valve 7, which acts as a solenoid valve to reduce the discharge pressure of the pilot pump 5 and generate pilot pressure. The electromagnetic proportional pressure reducing valve 7 is electrically connected to the controller 8 and generates pilot pressure in response to a signal from the controller 8. The controller 8 transmits a control signal to the electromagnetic proportional pressure reducing valve 7 according to the operating direction and amount of the operating lever 9, thereby controlling the electromagnetic proportional pressure reducing valve 7. As a result, the control valve 10 is switched to the neutral position 10A, the extended position 10B, and the retracted position 10C, and hydraulic fluid is supplied to and discharged from the rod side chamber 6a and the bottom side chamber 6b of the hydraulic cylinder 6.

[0018] Next, the configuration of the pilot cap unit 100 and the control valve 10 will be described in detail. Figure 2 is a plan view of the first pilot cap 40 of the first pilot cap unit 100a, Figure 3 is a side view of the first pilot cap 40 as seen from direction III in Figure 2, and Figure 4 is a cross-sectional view of the control valve 10. In Figures 2 and 3, the valve housing 30 and spool 25 to which the pilot cap unit 100 is attached are indicated by dashed lines.

[0019] The pilot cap unit 100 is attached to the valve housing 30 of the control valve 10. In the present embodiment, the plurality of control valves 10 have a common valve housing 30. The first pilot cap unit 100a and the second pilot cap unit 100b are each attached to the valve housing 30 and provided across the plurality of control valves 10. Since the plurality of control valves 10 each have a similar configuration, hereinafter, the configuration of one control valve 10 will be described as a representative.

[0020] As shown in FIGS. 2 to 4, the first pilot cap unit 100a includes a first pilot cap 40 attached to the valve housing 30 so as to face one end of the spool hole 31, and a first electromagnetic proportional pressure reducing valve 7a attached to the first pilot cap 40 and controlling the pressure of the pilot pressure oil as the pilot fluid supplied to the first pilot chamber 11a. By attaching the first pilot cap unit 100a to the valve housing 30, the first pilot chamber 11a is formed. Further, the second pilot cap unit 100b includes a second pilot cap 60 (see FIG. 4) attached to the valve housing 30 so as to face the other end of the spool hole 31, and a second electromagnetic proportional pressure reducing valve 7b (see FIG. 4) attached to the second pilot cap 60 and controlling the pressure of the pilot pressure oil supplied to the second pilot chamber 11b. By attaching the second pilot cap unit 100b to the valve housing 30, the second pilot chamber 11b is formed.

[0021] As shown in FIGS. 3 and 4, the control valve 10 includes a rectangular parallelepiped valve housing 30 and a spool 25 slidably incorporated in the valve housing 30. The valve housing 30 is formed with a spool hole 31 through which the spool 25 is slidably accommodated. The spool 25 has a main body portion 25a accommodated in the spool hole 31 and a spool end 25b coupled to one end of the spool 25 and extending into the first pilot chamber 11a. In the first pilot chamber 11a, a pair of spring receiving members 52 slidable along the outer periphery of the spool end 25b are accommodated, and a spring 51 as a biasing member is interposed between the pair of spring receiving members 52.

[0022] As shown in FIG. 4, the valve housing 30 has a supply port 32 communicating with the supply passage 20, an actuator port 33 communicating with the actuator passage 21, a derivation passage 34 communicating with the supply port 32 and guiding the hydraulic oil supplied from the supply port 32 to the actuator port 33, a derivation port 35 communicating with the derivation passage 34, a tank port 36 as a second port communicating with the tank passage 22, a drain passage (not shown) communicating with the tank 4, a drain port 37 as a first port communicating with the drain passage, and a neutral port 38 communicating with a neutral passage (not shown) and guiding the working fluid to the downstream control valve 10.

[0023] The actuator port 33, the derivation port 35, the tank port 36, the drain port 37, and the neutral port 38 open to the spool hole 31. The actuator port 33, the derivation port 35, and the tank port 36 are provided in two symmetrically arranged left and right. The neutral port 38 is provided in three near the axial center of the spool hole 31. Hereinafter, for the actuator port 33, the derivation port 35, and the tank port 36, the reference numerals of the ports provided on the right side of the neutral port 38 in FIG. 4 are suffixed with "a", and the reference numerals of the ports provided on the left side of the neutral port 38 are suffixed with "b" for explanation. Also, for the three neutral ports 38, the one provided in the center in FIG. 4 is also referred to as the neutral port 38a, the one provided on the right side is referred to as the neutral port 38b, and the one provided on the left side is referred to as the neutral port 38c.

[0024] In the spool hole 31, openings are provided in the following order from right to left in Figure 4: tank port 36a, actuator port 33a, outlet port 35a, neutral port 38b, neutral port 38a, neutral port 38c, outlet port 35b, actuator port 33b, tank port 36b, and drain port 37. The drain port 37 is located adjacent to the second pilot chamber 11b. Here, "the drain port 37 is located adjacent to the second pilot chamber 11b" means that no other ports are provided between the drain port 37 and the second pilot chamber 11b. The tank port 36a is located adjacent to the first pilot chamber 11a. In other words, no other ports are provided between the tank port 36a and the first pilot chamber 11a. A sub-spool 39 is provided in the outlet passage 34.

[0025] As shown in Figure 4, when no pilot pressure is supplied to any of the pilot chambers 11, the biasing force of the spring 51 causes the spool 25 to be in the neutral position, and the spool 25 blocks all communication between the outlet port 35a and the actuator port 33a, the actuator port 33a and the tank port 36a, the outlet port 35b and the actuator port 33b, and the actuator port 33b and the tank port 36b. In addition, the neutral port 38a communicates with the neutral ports 38b and 38c, and the hydraulic fluid supplied from the upstream control valve 10 to the neutral port 38a is supplied to the downstream control valve 10 through the neutral ports 38b and 38c.

[0026] When pilot pressure is introduced into the first pilot chamber 11a and the spool 25 moves to the left from the state shown in Figure 4, the outlet port 35b and the actuator port 33b communicate, and the outlet passage 34 communicates with the left actuator passage 21b in Figure 4. Also, the pressure of the hydraulic fluid introduced from the supply port 32 to the outlet passage 34 opens the sub-spool 39, and hydraulic fluid from the supply port 32 is supplied to the actuator through the outlet passage 34 and the actuator passage 21b. On the other hand, the actuator port 33a and the tank port 36a communicate, and the right actuator passage 21a in Figure 4 communicates with the tank passage 22. As a result, hydraulic fluid is discharged from the actuator to the tank 4 through the actuator passage 21a and the tank passage 22. In addition, the communication between the neutral port 38a and neutral port 38b, and between the neutral port 38a and neutral port 38c is blocked, blocking the flow of hydraulic fluid to the downstream control valve 10 through the neutral passage.

[0027] Furthermore, when pilot pressure is introduced into the second pilot chamber 11b and the spool 25 moves to the right from the state shown in Figure 4, the outlet port 35a and the actuator port 33a communicate, and the outlet passage 34 and the actuator passage 21a communicate. Also, the pressure of the hydraulic fluid introduced from the supply port 32 to the outlet passage 34 opens the sub-spool 39, and hydraulic fluid from the supply port 32 is supplied to the actuator through the outlet passage 34 and the actuator passage 21a. On the other hand, the actuator port 33b and the tank port 36b communicate, and the actuator passage 21b and the tank passage 22 communicate. As a result, hydraulic fluid is discharged from the actuator to the tank 4 through the actuator passage 21b and the tank passage 22. In addition, the communication between the neutral port 38a and the neutral port 38b, and between the neutral port 38a and the neutral port 38c is blocked, blocking the flow of hydraulic fluid to the downstream control valve 10 through the neutral passage.

[0028] In the following, the axial direction of the spool 25 will also be referred to as the Z direction. Furthermore, the multiple spools 25 and the multiple pilot chambers 11 are arranged in a direction perpendicular to the axial direction of the spool 25. For this reason, the arrangement direction of the spools 25 and pilot chambers 11 will also be referred to as the X direction. In addition, the direction perpendicular to both the axial direction of the spool 25 (Z direction) and the arrangement direction of the spools 25 (X direction) will also be referred to as the Y direction.

[0029] As shown in Figures 2 to 4, the first pilot cap 40 of the first pilot cap unit 100a has a cylindrical tube portion 41 provided coaxially with the spool 25, a spring housing hole 42 (see Figures 3 and 4) that houses a spring 51 for biasing the spool 25 and partitions the first pilot chamber 11a between it and the valve housing 30, and a protruding end portion 43 that protrudes from the tube portion 41 along the axial direction (Z direction) of the spool 25 on the side opposite to the valve housing 30. The protruding end portion 43 is provided to connect a plurality of tube portions 41 (see Figure 2). The first pilot cap 40 is attached to the side surface 31a of the valve housing 30 by fastening members such as bolts.

[0030] As shown in Figures 3 and 4, the first pilot cap 40 is attached to the valve housing 30 to define a first pilot chamber 11a facing one end of the spool 25. The spring 51, spring support member 52, and spool end 25b are housed in the first pilot chamber 11a. Similarly, the second pilot cap 60 of the second pilot cap unit 100b is attached to the valve housing 30 to define a second pilot chamber 11b facing the other end of the spool 25.

[0031] As shown in Figures 3 and 4, the first pilot cap 40 has a cap-side supply port 45 connected to the pilot pump 5 and supplied with pilot pressure oil from the pilot pump 5, a cap-side discharge port 46 for discharging pilot pressure oil to the tank 4, an outlet passage 48 for guiding pilot pressure oil from the cap-side supply port 45 to the electromagnetic proportional pressure reducing valve 7a, a valve body housing hole 55 as a housing hole capable of accommodating a part of the electromagnetic proportional pressure reducing valve 7a (specifically, a valve body not shown), a pilot passage 47 communicating with the valve body housing hole 55, a sealing member 50 that seals the opening on the outer surface 40b of the first pilot cap 40 in the pilot passage 47, and a cap-side drain passage 49 that communicates with the valve body housing hole 55 and guides pilot pressure oil discharged from the electromagnetic proportional pressure reducing valve 7a to the cap-side discharge port 46. Figure 4 shows a cross-sectional view passing through the pilot passage 47 and the valve body housing hole 55.

[0032] The cap-side supply port 45 and the cap-side discharge port 46 are provided on the protruding end 43 of the first pilot cap 40. In this embodiment, the cap-side supply port 45 and the cap-side discharge port 46 are provided side by side on one end face in the longitudinal direction (X direction) of the first pilot cap 40. The cap-side supply port 45 and the cap-side discharge port 46 are provided extending in the X direction.

[0033] As shown in Figures 3 and 4, the electromagnetic proportional pressure reducing valve 7a includes a valve body (not shown) housed in a valve body housing hole 55, a solenoid 56 that provides thrust to the valve body, and a spring (not shown) that provides a biasing force to the valve body in a direction opposite to the thrust of the solenoid 56. The electromagnetic proportional pressure reducing valve 7a controls the pilot pressure supplied to the first pilot chamber 11a according to the control current supplied to the solenoid 56. In this embodiment, the electromagnetic proportional pressure reducing valve 7a is a directly proportional type pressure reducing valve that increases the pilot pressure as the current supplied to the solenoid 56 increases.

[0034] The outlet passage 48 communicates with the cap-side supply port 45 and the valve body housing hole 55, and is formed linearly across the valve body housing hole 55 and the outer surface 40b of the first pilot cap 40. The opening on the outer surface 40b of the first pilot cap 40 in the outlet passage 48 is sealed by a sealing member 53. The pilot passage 47 passes through the valve body housing hole 55 and is formed linearly across the spring housing hole 42 and the outer surface 40b of the first pilot cap 40. Multiple outlet passages 48 and pilot passages 47 are provided corresponding to each electromagnetic proportional pressure reducing valve 7a. Each of the multiple pilot passages 47 communicates with the cap-side supply port 45. The pilot pressure oil guided from the cap-side supply port 45 through the outlet passage 48 to the valve body housing hole 55 is depressurized by the electromagnetic proportional pressure reducing valve 7a and guided to the first pilot chamber 11a through the pilot passage 47.

[0035] Multiple cap-side drain passages 49 are provided, corresponding to each electromagnetic proportional pressure reducing valve 7a. The cap-side drain passages 49 connect the cap-side discharge port 46 and the valve body housing hole 55. The cap-side drain passages 49 are provided so as to open to the opening 55a side of the valve body housing hole 55.

[0036] As shown in Figure 5, a plug 58 can be installed in place of the electromagnetic proportional pressure reducing valve 7a in the valve body housing hole 55. The plug 58 comprises a body portion 58a and a flange portion 58b. The body portion 58a is formed to be slightly smaller in diameter than the valve body housing hole 55, and the flange portion 58b is formed to be larger in diameter than the body portion 58a. When the plug 58 is installed in the valve body housing hole 55, the body portion 58a is housed in the valve body housing hole 55, and the flange portion 58b abuts against the outer surface of the first pilot cap 40. In addition, an O-ring 59 is provided as a sealing member between the outer circumferential surface of the body portion 58a and the inner circumferential surface of the valve body housing hole 55. This seals the valve body housing hole 55.

[0037] The main body portion 58a has a small-diameter portion 58c provided on the tip side of the plug 58 and a large-diameter portion 58d provided on the flange portion 58b side. A plug passage 58e is formed in the small-diameter portion 58c. The plug passage 58e is formed from an axial passage extending axially from the tip of the main body portion 58a and a radial passage extending radially from the axial passage. The plug passage 58e is formed so as to always communicate the pilot passage 47 and the cap-side drain passage 49 when the plug 58 is installed in the valve body housing hole 55. In this embodiment, the plug passage 58e communicates with a space A partitioned by the plug 58 and the valve body housing hole 55. Space A is an annular space partitioned by the outer circumferential surface of the small-diameter portion 58c, the stepped portion 58f between the small-diameter portion 58c and the large-diameter portion 58d, and the inner circumferential surface of the valve body housing hole 55, and communicates with the cap-side drain passage 49. The plug passage 58e and the cap-side drain passage 49 are in communication through space A. Therefore, when the plug 58 is installed in the valve body housing hole 55, the pilot passage 47 and the cap-side drain passage 49 are always in communication through the plug passage 58e. As a result, the first pilot chamber 11a is always in communication with the cap-side drain passage 49 through the pilot passage 47 and the plug passage 58e. Since multiple O-rings 59 are provided on either side of space A, space A is sealed by the O-rings 59, preventing hydraulic fluid from leaking out of space A.

[0038] As shown in Figure 4, the second pilot cap 60 of the second pilot cap unit 100b has a cylindrical portion 61 that is provided coaxially with the spool 25, and the second pilot chamber 11b is partitioned between it and the valve housing 30 by the cylindrical portion 61. The pilot pressure, reduced by the electromagnetic proportional pressure reducing valve 7b, is introduced into the second pilot chamber 11b. The configuration of the oil passage through which the pilot pressure is introduced from the pilot pump 5 to the second pilot chamber 11b via the electromagnetic proportional pressure reducing valve 7b can be the same as that of the first pilot cap 40, for example, so a detailed explanation is omitted.

[0039] In this case, depending on the user's usage, some control valves 10 may be left unused. For example, in some construction machines on which the control valves 10 are installed, the hydraulic cylinder 6 may not be attached to the actuator passage 21 of some control valves 10, and the spool 25 may be left unused. In such control valves 10, the hydraulic fluid discharged from the hydraulic pump 3 may leak into the pilot chamber 11 through the space between the inner surface of the spool hole 31 and the outer surface of the spool 25. If the unused spool 25 moves due to the pressure in the pilot chamber 11, the unused control valve 10 may malfunction. Furthermore, if the unused spool 25 moves due to the pressure in the pilot chamber 11, hydraulic fluid will flow in the unused control valve 10, which may reduce the pressure of the hydraulic fluid supplied to the control valve 10 in use and adversely affect the operation of the control valve 10 in use.

[0040] In contrast, in the first pilot cap unit 100a of this embodiment, the electromagnetic proportional pressure reducing valve 7a is removed from the valve body housing hole 55 corresponding to the unused control valve 10, and a plug 58 is installed in its place. When the plug 58 is installed in place of the electromagnetic proportional pressure reducing valve 7a in the valve body housing hole 55, the first pilot chamber 11a is always in communication with the cap-side drain passage 49 through the pilot passage 47 and the plug passage 58e. Therefore, even if hydraulic fluid leaks into the first pilot chamber 11a, the pressure inside the first pilot chamber 11a is prevented from rising. Thus, even if hydraulic fluid leaks into the pilot chamber 11 (specifically, the first pilot chamber 11a) of the unused control valve 10, the movement of the spool 25 due to the pressure of the leaked hydraulic fluid (movement in the direction that causes the second pilot chamber 11b to contract) is prevented by the plug 58. Therefore, malfunction of the unused control valve 10 is prevented.

[0041] Here, the drain port 37 is adjacent to the second pilot chamber 11b, and the tank port 36 is adjacent to the first pilot chamber 11a. The drain port 37 is at low pressure (atmospheric pressure) because it is in contact with the atmosphere, while the tank port 36 is at a slightly higher pressure than the drain port 37 because it is in contact with the tank 4, where pressure tends to build up. Therefore, if hydraulic fluid leaks into the first pilot chamber 11a through the space between the inner surface of the spool hole 31 and the outer surface of the spool 25, pressure tends to build up in the first pilot chamber 11a. However, since the first pilot chamber 11a is always in contact with the cap-side drain passage 49 via the plug passage 58e of the plug 58, the movement of the spool 25 due to pressure in the first pilot chamber 11a is prevented by the plug 58. On the other hand, unlike the tank port 36, the drain port 37 is at atmospheric pressure. Therefore, even if hydraulic fluid leaks into the second pilot chamber 11b through the space between the inner surface of the spool hole 31 and the outer surface of the spool 25, it is discharged to the drain port 37, so pressure is unlikely to build up inside the second pilot chamber 11b. As a result, by preventing the movement of the spool 25 due to the pressure of the hydraulic fluid in the first pilot chamber 11a, where pressure tends to build up, using the plug 58, and preventing the spool 25 from moving to one side in the axial direction, malfunction of the unused control valve 10 can be prevented.

[0042] Furthermore, in the first pilot cap unit 100a, if an unused control valve 10 is to be used, it is only necessary to remove the plug 58 and install the electromagnetic proportional pressure reducing valve 7a, thus making it easy to use the unused control valve 10. Moreover, by selectively attaching the electromagnetic proportional pressure reducing valve 7a and the plug 58 to the first pilot cap 40, it is possible to accommodate both the use and non-use states of the control valve 10, thus allowing the first pilot cap 40 to be standardized regardless of the usage state of the control valve 10.

[0043] According to the above-described embodiment, the following effects are achieved.

[0044] In the first pilot cap unit 100a, when a plug 58 is installed in place of the electromagnetic proportional pressure reducing valve 7a in the valve body housing hole 55, the first pilot chamber 11a is always in communication with the cap-side drain passage 49 through the pilot passage 47 and the plug passage 58e. Therefore, even if hydraulic fluid leaks into the first pilot chamber 11a, the pressure inside the first pilot chamber 11a is prevented from rising. Thus, even if hydraulic fluid leaks into the pilot chamber 11 (specifically, the first pilot chamber 11a) of an unused control valve 10, the movement of the spool 25 due to the pressure of the leaked hydraulic fluid is prevented by the plug 58. Therefore, malfunction of the unused control valve 10 is prevented. Furthermore, the unused control valve 10 can be easily used simply by removing the plug 58 and installing the electromagnetic proportional pressure reducing valve 7a.

[0045] The following modifications are also within the scope of the present invention, and it is possible to combine the configurations shown in the modifications with the configurations described in the embodiments described above, or to combine the configurations described in the following different modifications.

[0046] <Example 1> In the above embodiment, the plug 58 is attached to the first pilot cap 40 of the first pilot cap unit 100a in place of the electromagnetic proportional pressure reducing valve 7a. In addition, the plug 58 may also be attached to the second pilot cap 60 of the second pilot cap unit 100b in place of the electromagnetic proportional pressure reducing valve 7b. When the plug 58 is attached to the second pilot cap 60, the second pilot chamber 11b is always in communication with the cap-side drain passage formed in the second pilot cap 60 through the pilot passage and plug passage 58e formed in the second pilot cap 60. Therefore, the movement of the spool 25 due to the pressure in the second pilot chamber 11b (movement in the direction in which the first pilot chamber 11a contracts) is prevented by the plug 58. As a result, the movement of the spool 25 in both axial directions is restricted by the plug 58, so the movement of the unused spool 25 is more reliably prevented.

[0047] <Modification 2> In the above embodiment, an example was described in which a first pilot cap 40 is provided with a plurality of first pilot chambers 11a and a plurality of electromagnetic proportional pressure reducing valves 7a, but the present invention is not limited thereto. The present invention can also be applied when a single first pilot chamber 11a and a single electromagnetic proportional pressure reducing valve 7a are provided in the first pilot cap 40.

[0048] <Variation 3> In the above embodiment, an example was described in which the electromagnetic proportional pressure reducing valve 7 is a positively proportional type pressure reducing valve that increases the pilot pressure as the current supplied to the solenoid 56 increases, but the present invention is not limited to this. The electromagnetic proportional pressure reducing valve 7 may also be an inversely proportional type pressure reducing valve that decreases the pilot pressure as the current supplied to the solenoid 56 increases.

[0049] The configuration, operation, and effects of the embodiment of the present invention configured as described above will be summarized below.

[0050] A pilot cap unit 100 is attached to a control valve 10 having a valve housing 30 formed through which a spool hole 31 is formed, from which a spool 25 is slidably housed, and comprises a first pilot cap 40 attached to the valve housing 30 so as to face one end of the spool hole 31 and partitioning a first pilot chamber 11a between itself and the valve housing 30, wherein the first pilot cap 40 has a valve body housing hole 55 as a housing hole capable of housing a part of an electromagnetic proportional pressure reducing valve 7a which is an electromagnetic valve that controls the pressure of the pilot fluid supplied to the first pilot chamber 11a, and the valve body housing hole 55 The valve body has a pilot passage 47 that communicates with the electromagnetic proportional pressure reducing valve 7a and guides the pilot fluid, which has been depressurized by the electromagnetic proportional pressure reducing valve 7a, to the first pilot chamber 11a, and a cap-side drain passage 49 that communicates with the valve body housing hole 55 and guides the pilot fluid discharged from the electromagnetic proportional pressure reducing valve 7a. The electromagnetic proportional pressure reducing valve 7a can be installed in the valve body housing hole 55, and a plug 58 can be installed in place of the electromagnetic proportional pressure reducing valve 7a. When the plug 58 is installed in the valve body housing hole 55, the pilot passage 47 and the cap-side drain passage 49 are always in communication through the plug passage 58e formed in the plug 58.

[0051] In this configuration, when a plug 58 is installed in place of the electromagnetic proportional pressure reducing valve 7a in the valve body housing hole 55, the first pilot chamber 11a is always in communication with the cap-side drain passage 49 through the pilot passage 47 and the plug passage 58e. Therefore, even if working fluid leaks into the first pilot chamber 11a, the pressure inside the first pilot chamber 11a is prevented from rising. Thus, even if working fluid leaks into the pilot chamber 11 of an unused control valve 10, the movement of the spool 25 due to the pressure of the leaked working fluid is prevented by the plug 58. Therefore, malfunction of the unused control valve 10 is prevented.

[0052] Furthermore, the pilot cap unit 100 is attached to the valve housing 30 so as to face the other end of the spool hole 31 and further comprises a second pilot cap 60 that partitions the second pilot chamber 11b between itself and the valve housing 30. The valve housing 30 has a drain port 37 as a first port that opens into the spool hole 31 and is located adjacent to the second pilot chamber 11b and communicates with the atmosphere, and a tank port 36 as a second port that opens into the spool hole 31 and is located adjacent to the first pilot chamber 11a and has a higher pressure than the drain port 37. A plug 58 can be attached to the first pilot cap 40 in place of the electromagnetic proportional pressure reducing valve 7a.

[0053] In this configuration, the second pilot chamber 11b is adjacent to a drain port 37 that communicates with the atmosphere, while the first pilot chamber 11a is adjacent to a tank port 36 that has a higher pressure than the drain port 37. Because the drain port 37 communicates with the atmosphere, pressure is less likely to build up in the second pilot chamber 11b, but because the tank port 36 has a higher pressure than the drain port 37, pressure is more likely to build up in the first pilot chamber 11a than in the second pilot chamber 11b. Therefore, if working fluid leaks out through the space between the inner surface of the spool hole 31 and the outer surface of the spool 25, pressure is more likely to build up in the first pilot chamber 11a than in the second pilot chamber 11b. However, the movement of the spool 25 due to the pressure in the first pilot chamber 11a can be prevented by the plug 58.

[0054] Although embodiments of the present invention have been described above, these embodiments only represent a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments. [Explanation of Symbols]

[0055] 7a, 7b... Solenoid proportional pressure reducing valve (solenoid valve), 10... Control valve, 11a... First pilot chamber, 11b... Second pilot chamber, 30... Valve housing, 31... Spool hole, 32... Spool, 36... Tank port (second port), 37... Drain port (first port), 40... First pilot cap, 47... Pilot passage, 49... Cap-side drain passage (drain passage), 55... Valve body housing hole (housing hole), 58... Plug, 58e... Plug passage, 60... Second pilot cap, 100a, 100b... Pilot cap unit

Claims

1. A pilot cap unit to be attached to a control valve having a valve housing formed through which a spool hole is formed, in which a spool is slidably housed, The valve housing is attached to the valve housing so as to face one end of the spool hole, and a first pilot cap is attached to the valve housing to partition a first pilot chamber between itself and the valve housing, The first pilot cap is A housing hole capable of accommodating a part of a solenoid valve that controls the pressure of the pilot fluid supplied to the first pilot chamber, A pilot passage that communicates with the aforementioned housing hole and guides the pilot fluid, which has been depressurized by the solenoid valve, to the first pilot chamber, It has a drain passage that communicates with the aforementioned housing hole and through which pilot fluid discharged from the solenoid valve is guided, The aforementioned housing hole is capable of housing the solenoid valve, and a plug can be installed in its place. A pilot cap unit characterized in that, when the plug is installed in the housing hole, the pilot passage and the drain passage are always in communication through the plug passage formed in the plug.

2. A pilot cap unit according to claim 1, The valve housing is further equipped with a second pilot cap that is attached to the valve housing so as to face the other end of the spool hole and separates a second pilot chamber from the valve housing, The valve housing has a first port that opens into the spool hole and is provided adjacent to the second pilot chamber and communicates with the atmosphere, and a second port that opens into the spool hole and is provided adjacent to the first pilot chamber and has a higher pressure than the first port. A pilot cap unit characterized in that a plug can be attached to the first pilot cap in place of the solenoid valve.

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