Pilot cover unit

Abstract

The first pilot cover (40) has: a valve body housing hole (55) capable of housing a part of an electromagnetic proportional pressure reducing valve (7a) for controlling the pressure of the pilot fluid supplied to the first pilot chamber (11a); a pilot passage (47) that communicates with the valve body housing hole (55) and guides the pilot fluid decompressed by the electromagnetic proportional pressure reducing valve (7a) to the first pilot chamber (11a); and a cover-side drainage passage (49) that communicates with the valve body housing hole (55) in which the electromagnetic proportional pressure reducing valve (7a) can be mounted and the plug (58) can be mounted in place of the electromagnetic proportional pressure reducing valve (7a), and that guides the pilot fluid discharged from the electromagnetic proportional pressure reducing valve (7a) while the plug (58) is mounted in the valve body housing hole (55), and that drains the pilot fluid discharged from the electromagnetic proportional pressure reducing valve (7a) to the cover-side drainage passage (49) in a state in which the plug (58) is mounted in the valve body housing hole (55). The pilot passage (47) and the lid-side drainage passage (49) are always in communication with each other via a plug passage (58e) formed in the plug (58).

Description

Technical Field

[0001] The invention relates to a pilot cover unit. Background Art

[0002] Japanese Patent Publication No. JP2019-190635A discloses a control valve having a cover. The cover comprises: a pilot cover, which is mounted on a valve housing in which a slide valve is assembled, and divides a pilot chamber together with the valve housing; and a solenoid valve, which is mounted on the pilot cover and controls the pressure of a working fluid supplied to the pilot chamber. Summary of the invention

[0003] In the control valve described in Japanese Patent Publication JP2019-190635A, a part of the control valve is sometimes set to unused due to the user's usage method. In the control valve described in Japanese Patent Publication JP2019-190635A, the working fluid ejected from the pump may leak into the unused pilot chamber through the inner peripheral surface of the sliding hole for sliding the unused slide valve and the outer peripheral surface of the unused slide valve. In this case, the unused slide valve moves and the unused control valve malfunctions.

[0004] An object of the present invention is to prevent malfunction of an unused control valve.

[0005] Means used to solve technical problems

[0006] According to one embodiment of the present invention, a pilot cover unit is installed on a control valve, the control valve has a valve housing through which a sliding valve hole is formed, and the sliding valve is slidably accommodated in the sliding valve hole, the pilot cover unit has a first pilot cover, the first pilot cover is installed on the valve housing and faces one end of the sliding valve hole, and a first pilot chamber is divided between the first pilot cover and the valve housing, the first pilot cover has: a receiving hole, which can accommodate a part of an electromagnetic valve, the electromagnetic valve controls the pressure of a pilot fluid supplied to the first pilot chamber; a pilot passage, which is connected to the receiving hole and guides the pilot fluid after the pressure is reduced by the electromagnetic valve to the first pilot chamber; a drainage passage, which is connected to the receiving hole and guides the pilot fluid discharged from the electromagnetic valve, the electromagnetic valve can be installed in the receiving hole, and a plug can be installed to replace the electromagnetic valve, and when the plug is installed in the receiving hole, the pilot passage and the drainage passage are always connected via the plug passage formed in the plug. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 The fluid pressure circuit diagram of the fluid pressure control device including the control valve.

[0008] Figure 2It is a plan view of a first pilot cover of a pilot cover unit according to an embodiment of the present invention.

[0009] Figure 3 For Figure 2 A side view of the first pilot cover as viewed from direction III.

[0010] Figure 4 It is a cross-sectional view showing a pilot cover unit and control according to an embodiment of the present invention.

[0011] Figure 5 This is an enlarged cross-sectional view showing a state where the plug is mounted on the first pilot cover. DETAILED DESCRIPTION

[0012] The first pilot cover unit 100a and the second pilot cover unit 100b according to the embodiment of the present invention will be described with reference to the drawings. Hereinafter, the first pilot cover unit 100a and the second pilot cover unit 100b will be simply and collectively referred to as “pilot cover unit 100”.

[0013] The pilot cover unit 100 and the control valve 10 equipped with the pilot cover unit 100 are provided in the fluid pressure control device 1. The fluid pressure control device 1 is a device for controlling an actuator driven by a working fluid ejected from a pump, and is mounted on, for example, a working machine such as a construction machine, an agricultural machine, or an industrial machine. Hereinafter, a case will be described in which the fluid pressure control device 1 is mounted on a hydraulic excavator and is used to control the operation of an actuator such as a hydraulic cylinder for driving a hydraulic motor for traveling, a boom, an arm, a bucket, etc. In addition, although an example of using working oil as a working fluid for driving an actuator of a hydraulic excavator is described, other fluids such as working water may also be used as the working fluid.

[0014] First, refer to Figure 1 , the hydraulic circuit of the fluid pressure control device 1 is described. The fluid pressure control device 1 includes: a hydraulic pump 3; a hydraulic cylinder 6 as an actuator, which is driven by the working oil ejected from the hydraulic pump 3; a supply passage 20, which supplies the working oil ejected from the hydraulic pump 3; and a control valve 10, which is provided in the supply passage 20 and controls the flow of the working oil supplied to the hydraulic cylinder 6. The hydraulic cylinder 6 and the control valve 10 are provided in plurality. Figure 1 In FIG. 1 , one hydraulic cylinder 6 and two control valves 10 are representatively shown.

[0015] The hydraulic cylinder 3 is driven by an engine mounted on the hydraulic excavator. The hydraulic pump 3 is not limited thereto and may be driven by an electric motor. The working oil ejected from the hydraulic pump 3 is guided to the control valve 10 through the supply passage 20. The working oil is guided to the rod side chamber 6a and the bottom side chamber 6b of the hydraulic cylinder 6 via a pair of actuator passages 21. The pair of actuator passages 21 are connected to the supply passage 20 on one side and to the fluid tank passage 22 connected to the fluid tank 4 on the other side according to the gear position of the control valve 10.

[0016] The control valve 10 is an eight-way, three-position spool valve. In the present embodiment, a plurality of control valves 10 having the same structure are provided in correspondence with each hydraulic cylinder 6. The switching valve 10 guides the pilot pressure to the pair of pilot chambers 11 via the pilot passage 16 according to the operation direction and operation amount of the operating handle 9 performed by the operator, thereby switching the gear position. The control valve 10 switches the gear position between the neutral gear position 10A, the extension gear position 10B, and the retraction gear position 10C according to 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 as an electromagnetic valve that reduces the discharge pressure of the pilot pump 5 to generate the pilot pressure. The electromagnetic proportional pressure reducing valve 7 is electrically connected to the controller 8, and generates the pilot pressure according to the signal from the controller 8. The controller 8 sends a control signal corresponding to the operation direction and operation amount of the operating handle 9 to the electromagnetic proportional pressure reducing valve 7, thereby controlling the electromagnetic proportional pressure reducing valve 7. Thereby, the control valve 10 is switched to the neutral gear position 10A, the extension gear position 10B, and the retraction gear position 10C, and the working oil is supplied and discharged to the rod side chamber 6a and the bottom side chamber 6b of the hydraulic cylinder 6.

[0018] Next, the structures of the pilot cover unit 110 and the control valve 10 will be described in detail. Figure 2 is a top view of the first pilot cover 40 of the first pilot cover unit 100a, Figure 3 For Figure 2 A side view of the first pilot cover 40 observed from direction III, Figure 4 FIG. 1 is a cross-sectional view of the control valve 10. Figure 2 as well as Figure 3 In FIG. 1 , the valve housing 30 to which the pilot cover unit 100 is mounted and the spool valve 25 are indicated by two-dot chain lines.

[0019] The pilot cover unit 100 is mounted on 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 cover unit 100a and the second pilot cover unit 100b are respectively mounted on the valve housing 30 and are arranged to span the plurality of control valves 10. Since the plurality of control valves 10 have the same structure, the structure of one control valve 10 will be representatively described below.

[0020] like Figures 2 to 4 As shown, the first pilot cover unit 100a includes: a first pilot cover 40, which is installed on the valve housing 30 in a manner facing one end of the slide valve hole 31; a first electromagnetic proportional pressure reducing valve 7a, which is installed on the first pilot cover 40 and controls the pressure of the pilot pressure oil as the pilot fluid supplied to the first pilot chamber 11a. The first pilot cover unit 100a is installed on the valve housing 30, thereby forming the first pilot chamber 11a. In addition, the second pilot cover unit 100b includes: a second pilot cover 60 (refer to Figure 4 ), which is mounted on the valve housing 30 in a manner facing the other end of the slide valve hole 31; the second electromagnetic proportional pressure reducing valve 7b (refer to Figure 4 ), which is mounted on the second pilot cover 60, and controls the pressure of the pilot pressure oil supplied to the second pilot chamber 11b. The second pilot cover unit 100b is mounted on the valve housing 30, thereby forming the second pilot chamber 11b.

[0021] like Figure 3 , Figure 4 As shown, the control valve 10 includes: a rectangular parallelepiped valve housing 30; and a slide valve 25 which is slidably mounted in the valve housing 30. A slide valve hole 31 is formed through the valve housing 30 to accommodate the slide valve 25 in a slidable manner. The slide valve 25 includes: a body portion 25a which is accommodated in the slide valve hole 31; and a slide valve end 25b which is coupled to one end of the slide valve 25 and extends in the first pilot chamber 11a. In the first pilot chamber 11a, a pair of spring support members 52 which can slide along the outer periphery of the slide valve end 25b are accommodated, and a spring 51 as a biasing member is interposed between the pair of spring support members 52.

[0022] like Figure 4As shown, the valve housing 30 has: a supply port 32, which is connected to the supply passage 20; an actuator port 33, which is connected to the actuator passage 21; a lead-out passage 34, which is connected to the supply port 32 and guides the working oil supplied from the supply port 32 to the actuator port 33; a lead-out port 35, which is connected to the lead-out passage 34; a fluid tank port 36 as a second port, which is connected to the fluid tank passage 22; a drain passage (not shown in the figure), which is connected to the fluid tank 4; a drain port 37 as a first port, which is connected to the drain passage; and a neutral port 38, which is connected to the neutral passage (not shown in the figure) and guides the working fluid to the control valve 10 on the downstream side.

[0023] The actuator port 33, the outlet port 35, the tank port 36, the drain port 37, and the neutral port 38 are opened at the slide valve hole 31. Two actuator ports 33, outlet ports 35, and tank ports 36 are provided symmetrically. Three neutral ports 38 are provided near the axial center of the slide valve hole 31. Figure 4 In the description, the ports provided on the right side of the neutral port 38 are labeled with "a", and the ports provided on the left side of the neutral port 38 are labeled with "b". Figure 4 The port provided at the center is referred to as a neutral port 38a, the port provided at the right side is referred to as a neutral port 38b, and the port provided at the left side is referred to as a neutral port 38c.

[0024] In the slide valve hole 31, Figure 4 From the right side in the figure, the fluid box port 36a, the actuator port 33a, the outlet port 35a, the neutral port 38b, the neutral port 38a, the neutral port 38c, the outlet port 35b, the actuator port 33b, the fluid box port 36b, and the drain port 37 are opened in sequence. The drain port 37 is arranged adjacent to the second pilot chamber 11b. Here, "the drain port 37 is adjacent to the second pilot chamber 11b" means that no other port is arranged between the drain port 37 and the second pilot chamber 11b. The fluid port 36a is arranged adjacent to the first pilot chamber 11a. That is, no other port is arranged between the fluid port 36a and the first pilot chamber 11a. On the outlet passage 34, a secondary slide valve 39 is arranged.

[0025] like Figure 4As shown in the state shown in FIG. 1 , in a state where the pilot pressure is not introduced to any pilot chamber 11, the spool valve 25 is in a neutral position due to the biasing force of the spring 51, and the 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 are all cut off by the spool valve 25. In addition, the neutral port 38a is communicated with the neutral port 38b and the neutral port 38c, and the working oil introduced from the control valve 10 on the upstream side to the neutral port 38a is introduced to the control valve 10 on the downstream side via the neutral ports 38b and the neutral port 38c.

[0026] When the pilot pressure is introduced to the first pilot chamber 11a, the spool valve 25 is Figure 4 When the actuator moves to the left from the state shown in the figure, the outlet port 35b is connected to the actuator port 33b, and the outlet passage 34 and Figure 4 The auxiliary spool valve 39 is opened by the pressure of the working oil guided from the supply port 32 to the outlet passage 34, and the working oil from the supply port 32 is supplied to the actuator via the outlet passage 34 and the actuator passage 21b. On the other hand, the actuator port 33a is connected to the fluid tank port 36a. Figure 4 The actuator passage 21a on the right side of the valve 21 is connected to the fluid tank passage 22. As a result, the hydraulic oil is discharged from the actuator to the fluid tank 4 via the actuator passage 21a and the fluid 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 cut off, and the flow of the hydraulic oil to the control valve 10 on the downstream side via the neutral passage is cut off.

[0027] In addition, when the pilot pressure is introduced to the second pilot chamber 11b, the spool valve 25 is Figure 4 When the valve 39 moves to the right from the state shown, the outlet port 35a is connected to the actuator port 33a, and the outlet passage 34 is connected to the actuator passage 21a. In addition, the auxiliary slide valve 39 is opened by the pressure of the working oil guided from the supply port 32 to the outlet passage 34, and the working oil from the supply port 32 is supplied to the actuator via the outlet passage 34 and the actuator passage 21a. On the other hand, the actuator port 33b is connected to the fluid tank port 36b, and the actuator passage 21b is connected to the fluid tank passage 22. Thereby, the working oil is discharged from the actuator to the fluid tank 4 via the actuator passage 21b and the fluid 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 cut off, and the flow of the working oil to the control valve 10 on the downstream side via the neutral passage is cut off.

[0028] In addition, hereinafter, the axial direction of the slide valve 25 is also referred to as the Z direction. In addition, the plurality of slide valves 25 and the plurality of pilot chambers 11 are arranged in a direction orthogonal to the axial direction of the slide valve 25. Therefore, the arrangement direction of the slide valve 25 and the pilot chamber 11 is also referred to as the X direction. In addition, the direction orthogonal to each of the axial direction of the slide valve 25 (Z direction) and the arrangement direction of the slide valve 25 (X direction) is also referred to as the Y direction.

[0029] like Figures 2 to 4 As shown, the first pilot cover 40 of the first pilot cover unit 100a has: a cylindrical barrel 41, which is arranged coaxially with the slide valve 25; a spring receiving hole 42 (refer to Figure 3 , Figure 4 ), which accommodates the spring 51 for urging the slide valve 25 and defines the first pilot chamber 11a between the valve housing 30; and the protruding end portion 43, which protrudes from the cylinder portion 41 along the axial direction (Z direction) of the slide valve 25 to the side opposite to the valve housing 30. The protruding end portion 43 is provided in a manner of connecting a plurality of cylinder portions 41 (refer to Figure 2 ). The first pilot cover 40 is attached to the side surface 31 a of the valve housing 30 by fastening members such as bolts.

[0030] like Figure 3 , Figure 4 As shown, the first pilot cover 40 is mounted on the valve housing 30, thereby defining a first pilot chamber 11a to which one end of the slide valve 25 faces. The spring 51, the spring support member 52, and the slide valve end 25b are accommodated in the first pilot chamber 11a. Similarly, the second pilot cover 60 of the second pilot cover unit 100 is mounted on the valve housing 30, thereby defining a second pilot chamber 11b to which the other end of the slide valve 25 faces.

[0031] like Figure 3 as well as Figure 4 As shown, the first pilot cover 40 has: a cover-side supply port 45, which is connected to the pilot pump 5 and is supplied with pilot pressure oil from the pilot pump 5; a cover-side discharge port 46, which discharges the pilot pressure oil to the fluid box 4; a lead-out passage 48, which guides the pilot pressure oil from the cover-side supply port 45 to the electromagnetic proportional pressure reducing valve 7a; a valve body receiving hole 55 as a receiving hole, which can accommodate a part of the electromagnetic proportional pressure reducing valve 7a (specifically, the valve body not shown); a pilot passage 47, which is connected to the valve body receiving hole 55; a sealing component 50, which seals the opening of the outer surface 40b of the first pilot cover 40 in the pilot passage 47; a cover-side drainage passage 49 as a drainage passage, which is connected to the valve body receiving hole 55 and guides the pilot pressure oil discharged from the electromagnetic proportional pressure reducing valve 7a to the cover-side discharge port 46. In addition, Figure 4 , a cross-sectional view passing through the pilot passage 47 and the valve body accommodating hole 55 is shown.

[0032] The cover side supply port 45 and the cover side discharge port 46 are provided at the protruding end portion 43 of the first pilot cover 40. In the present embodiment, the cover side supply port 45 and the cover side discharge port 46 are arranged side by side on one end surface in the long side direction (X direction) of the first pilot cover 40. The cover side supply port 45 and the cover side discharge port 46 are provided so as to extend in the X direction.

[0033] like Figure 3 as well as Figure 4 As shown in FIG. 1 , the electromagnetic proportional pressure reducing valve 7a includes: a valve body (not shown) accommodated in the valve body accommodation hole 55; a solenoid 56 that applies a thrust to the valve body; and a spring (not shown) that applies a force to the valve body in a direction opposing 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 the present embodiment, the electromagnetic proportional pressure reducing valve 7a is a proportional pressure reducing valve that increases the pilot pressure as the current supplied to the solenoid 56 increases.

[0034] The outlet passage 48 is communicated with the cover side supply port 45 and the valve body receiving hole 55, and is formed in a straight line in a manner spanning the valve body receiving hole 55 and the outer surface 40b of the first pilot cover 40. The opening of the outer surface 40b of the first pilot cover 40 in the outlet passage 48 is sealed by the sealing member 53. The pilot passage 47 passes through the valve body receiving hole 55, and is formed in a straight line in a manner spanning the spring receiving hole 42 and the outer surface 40b of the first pilot cover 40. A plurality of the outlet passages 48 and the pilot passages 47 are provided for each electromagnetic proportional pressure reducing valve 7a. The plurality of pilot passages 47 are respectively communicated with the cover side supply port 45. The pilot pressure oil guided from the cover side supply port 45 to the valve body receiving hole 55 via the outlet passage 48 is reduced in pressure by the electromagnetic proportional pressure reducing valve 7a, and is guided to the first pilot chamber 11a via the pilot passage 47.

[0035] A plurality of cover-side drain passages 49 are provided corresponding to the electromagnetic proportional pressure reducing valves 7a. The cover-side drain passages 49 connect the cover-side drain port 46 and the valve body accommodating hole 55. The cover-side drain passages 49 are provided to open at the opening 55a side of the valve body accommodating hole 55.

[0036] like Figure 5As shown in the figure, a plug 58 can be installed on the valve body receiving hole 55 to replace the electromagnetic proportional pressure reducing valve 7a. The plug 58 includes a main body 58a and a flange 58b. The main body 58a is formed to have a slightly smaller diameter than the valve body receiving hole 55, and the flange 58b is formed to have a larger diameter than the main body 58a. When the plug 58 is installed in the valve body receiving hole 55, the main body 58a is received in the valve body receiving hole 55, and the flange 58b abuts against the outer surface of the first pilot cover 40. In addition, an O-ring 59 as a sealing member is provided between the outer peripheral surface of the main body 58a and the inner peripheral surface of the valve body receiving hole 55. Thereby, the valve body receiving hole 55 is sealed.

[0037] The main body 58a includes a small diameter portion 58c provided at the top end side of the plug 58 and a large diameter portion 58d provided at the flange 58b side. A plug passage 58e is formed in the small diameter portion 58c. The plug passage 58e is formed by an axial passage extending in the axial direction from the top end of the main body 58a and a radial passage extending in the radial direction from the axial passage. The plug passage 58e is formed so as to always communicate the pilot passage 47 and the cover side drainage passage 49 when the plug 58 is installed in the valve body receiving hole 55. In the present embodiment, the plug passage 58e communicates with a space A defined by the plug 58 and the valve body receiving hole 55. The space A is an annular space defined by the outer peripheral surface of the small diameter portion 58c, the step portion 58f between the small diameter portion 58c and the large diameter portion 58d, and the inner peripheral surface of the valve body receiving hole 55, and communicates with the cover side drainage passage 49. The plug passage 58e and the cover-side drain passage 49 are connected via the space A. Thus, in a state where the plug 58 is installed in the valve body receiving hole 55, the pilot passage 47 and the cover-side drain passage 49 are always connected via the plug passage 58e. Thus, the first pilot chamber 11a is always connected to the cover-side drain passage 49 via the pilot passage 47 and the plug passage 58e. Since a plurality of O-rings 59 are provided across the space A, the space A is sealed by the O-rings 59, thereby preventing the hydraulic oil from leaking out of the space A.

[0038] like Figure 4 As shown, the second pilot cover 60 of the second pilot cover unit 100b has a cylindrical barrel 61 provided coaxially with the slide valve 25, and the second pilot chamber 11b is divided between the barrel 61 and the valve housing 30. The pilot pressure reduced by the electromagnetic proportional pressure reducing valve 7b is guided to the second pilot chamber 11b. Regarding the structure of the oil path for guiding the pilot pressure from the pilot pump 5 via the electromagnetic proportional pressure reducing valve 7b to the second pilot chamber 11b, for example, the same structure as the first pilot cover 40 can be applied, and therefore, detailed description is omitted.

[0039] Here, in the control valve 10, a part of the control valve 10 may be set to unused due to the user's usage method. For example, due to the construction machinery on which the control valve 10 is mounted, the hydraulic cylinder 6 is not installed on the actuator passage 21 of a part of the control valve 10, and the slide valve 25 may become unused. In such a control valve 10, the working oil ejected from the hydraulic pump 3 may leak into the pilot chamber 11 through the inner peripheral surface of the slide valve hole 31 and the outer peripheral surface of the slide valve 25. When the unused slide valve 25 moves due to the pressure of the pilot chamber 11, the unused control valve 10 malfunctions. In addition, when the unused slide valve 25 moves due to the pressure of the pilot chamber 11, the flow of working oil is generated in the unused control valve 10, thereby reducing the pressure of the working oil supplied to the control valve 10 in use, which may have an adverse effect on the operation of the control valve 10 in use.

[0040] In contrast, in the first pilot cover unit 100a of the present embodiment, the electromagnetic proportional pressure reducing valve 7a is removed from the valve body receiving 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 the valve body receiving hole 55 in place of the electromagnetic proportional pressure reducing valve 7a, the first pilot chamber 11 is always connected to the cover-side drain passage 49 via the pilot passage 47 and the plug passage 58e. Therefore, even if the working oil leaks into the first pilot chamber 11a, the pressure in the first pilot chamber 11a is prevented from rising. Thus, even if the working oil leaks into the pilot chamber 11 (specifically, the first pilot chamber 11a) of the unused control valve 10, the movement of the slide valve 25 (movement in the direction of contraction of the second pilot chamber 11b) caused by the pressure of the leaked working fluid is prevented by the plug 58. Thus, 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. Since the drain port 37 is connected to the atmosphere, it is at low pressure (atmospheric pressure), while the tank port 36 is connected to the tank 4 which is easily filled with pressure, and therefore, the pressure is slightly higher than that of the drain port 37. Therefore, when the working oil leaks into the first pilot chamber 11a through the inner peripheral surface of the spool hole 31 and the outer peripheral surface of the spool 25, the pressure is easily filled in the first pilot chamber 11a. However, the first pilot chamber 11a is always connected to the cover side drain passage 49 due to the plug passage 58e of the plug 58, so the movement of the spool 25 caused by the pressure of the first pilot chamber 11a is prevented by the plug 58. On the other hand, the drain port 37 is at atmospheric pressure, unlike the tank port 36. Therefore, even if the working oil leaks into the second pilot chamber 11b through the inner peripheral surface of the spool hole 31 and the outer peripheral surface of the spool 25, it is discharged to the drain port 37, so that it is difficult for the pressure to fill the second pilot chamber 11b. Therefore, the movement of the spool 25 caused by the pressure of the working oil in the first pilot chamber 11a, which is easily filled with pressure, is prevented only by using the plug 58, and the movement of the spool 25 in one axial direction is prevented, so that the malfunction of the unused control valve 10 can be prevented.

[0042] In addition, in the first pilot cover unit 100a, when the unused control valve 10 is used, it is sufficient to remove the plug 58 and install the electromagnetic proportional pressure reducing valve 7a, so that the unused control valve 10 can be easily used. In addition, by selectively installing the electromagnetic proportional pressure reducing valve 7a and the plug 58 on the first pilot cover 40, it is possible to cope with any use state of the control valve 10, that is, use or non-use. Therefore, the first pilot cover 40 can be made common regardless of the use state of the control valve 10.

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

[0044] In the first pilot cover unit 100a, when the plug 58 is installed in the valve body receiving hole 55 in place of the electromagnetic proportional pressure reducing valve 7a, the first pilot chamber 11a is always connected to the cover side drain passage 49 via the pilot passage 47 and the plug passage 58e. Therefore, even if the working oil leaks into the first pilot chamber 11a, the pressure in the first pilot chamber 11a is prevented from rising. Thus, even if the working oil leaks into the pilot chamber 11 (specifically, the first pilot chamber 11a) of the unused control valve 10, the plug 58 prevents the movement of the slide valve 25 due to the pressure of the leaked working fluid. Thus, malfunction of the unused control valve 10 is prevented. In addition, the unused control valve 10 can be easily used by simply removing the plug 58 and installing the electromagnetic proportional pressure reducing valve 7a.

[0045] The following modified examples are also within the scope of the present invention, and it is possible to combine the configuration shown in the modified examples with the configuration described in the above embodiment, or to combine the configurations described in the following different modified examples with each other.

[0046] <Variation 1>

[0047] In the above embodiment, the plug 58 is installed only on the first pilot cover 40 of the first pilot cover unit 100a in place of the electromagnetic proportional pressure reducing valve 7a. In addition, the following structure may be adopted, that is, the plug 58 is installed on the second pilot cover 60 of the second pilot cover unit 100b in place of the electromagnetic proportional pressure reducing valve 7b. In the state where the plug 58 is installed on the second pilot cover 60, the second pilot chamber 11b is always connected to the cover-side drainage passage formed in the second pilot cover 60 via the pilot passage formed in the second pilot cover 60 and the plug passage 58e. As a result, the movement of the slide valve 25 (movement in the direction in which the second pilot chamber 11a contracts) caused by the pressure in the second pilot chamber 11b is prevented by the plug 58. In this way, the movement of the slide valve 25 to both sides in the axial direction is restricted by the plug 58, so that the movement of the unused slide valve 25 is further reliably prevented.

[0048] <Variation 2>

[0049] Although the above embodiment describes an example in which a plurality of first pilot chambers 11a and a plurality of electromagnetic proportional pressure reducing valves 7a are provided on the first pilot cover 40, the present invention is not limited thereto. Even when a single first pilot chamber 11a and a single electromagnetic proportional pressure reducing valve 7a are provided on the first pilot cover 40, the present invention can be applied.

[0050] <Variation 3>

[0051] Although the electromagnetic proportional pressure reducing valve 7 is described as an example of a direct proportional pressure reducing valve in which the pilot pressure is increased as the current supplied to the solenoid 56 is higher in the above embodiment, the present invention is not limited thereto. The electromagnetic proportional pressure reducing valve 7 may also be an inverse proportional pressure reducing valve in which the pilot pressure is decreased as the current supplied to the solenoid 56 is higher.

[0052] The structure, function, and effect of the embodiment of the present invention configured as above will be summarized and described.

[0053] The pilot cover unit 100 is installed on the control valve 10, and the control valve 10 has a valve housing 30 through which a slide valve hole 31 is formed, and the slide valve 25 is slidably received in the slide valve hole 31. The pilot cover unit 100 includes a first pilot cover 40, which is installed on the valve housing 30 and faces one end of the slide valve hole 31, and divides a first pilot chamber 11a between the first pilot cover 40 and the valve housing 30. The first pilot cover 40 has: a valve body receiving hole 55 as a receiving hole, which can receive a portion of the electromagnetic proportional pressure reducing valve 7a as an electromagnetic valve that controls the pressure of the pilot fluid supplied to the first pilot chamber 11a part; a pilot passage 47, which is connected to the valve body accommodating hole 55, and guides the pilot fluid after the pressure reduction by the electromagnetic proportional pressure reducing valve 7a to the first pilot chamber 11a; a cover side drainage passage 49 as a drainage passage, which is connected to the valve body accommodating 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 accommodating hole 55, and a plug 58 can be installed to replace the electromagnetic proportional pressure reducing valve 7a. When the plug 58 is installed in the valve body accommodating hole 55, the pilot passage 47 and the cover side drainage passage 49 are always connected via the plug passage 58e formed in the plug 58.

[0054] In this structure, when the plug 58 is installed in the valve body receiving hole 55 instead of the electromagnetic proportional pressure reducing valve 7a, the first pilot chamber 11 is always connected to the cover side drain passage 49 via the pilot passage 47 and the plug passage 58e. Therefore, even if the working fluid leaks into the first pilot chamber 11a, the pressure in the first pilot chamber 11a is prevented from rising. Therefore, even if the working fluid leaks into the pilot chamber 11 of the unused control valve 10, the plug 58 prevents the movement of the spool 25 due to the pressure of the leaked working fluid. As a result, malfunction of the unused control valve 10 is prevented.

[0055] In addition, the pilot cover unit 10 also has a second pilot cover 60, which is installed on the valve housing 30 and faces the other end of the sliding valve hole 31, and divides the second pilot chamber 11b between the second pilot cover 60 and the valve housing 30. The valve housing 30 has: a drain port 37 as a first port, which opens at the sliding valve hole 31 and is arranged to be adjacent to the second pilot chamber 11b and connected to the atmosphere; a fluid tank port 36 as a second port, which opens at the sliding valve hole 31 and is arranged to be adjacent to the first pilot chamber 11a, and has a higher pressure than the drain port 37. On the first pilot cover 40, a plug 58 can be installed to replace the electromagnetic proportional pressure reducing valve 7a.

[0056] In this structure, the drain port 37 connected to the atmosphere is adjacent to the second pilot chamber 11b, and the fluid tank port 36 having a higher pressure than the drain port 37 is adjacent to the first pilot chamber 11a. Since the drain port 37 is connected to the atmosphere, it is difficult for the pressure to fill the second pilot chamber 11b, but since the pressure of the fluid tank port 36 is higher than that of the drain port 37, it is easier for the pressure to fill the first pilot chamber 11a than the second pilot chamber 11b. Therefore, when the working fluid leaks through the inner peripheral surface of the slide valve hole 31 and the outer peripheral surface of the slide valve 25, it is easier for the pressure to fill the first pilot chamber 11a than the second pilot chamber 11b. However, the plug 58 can prevent the movement of the slide valve 25 caused by the pressure of the first pilot chamber 11a.

[0057] Although the embodiments of the present invention have been described above, the above embodiments merely represent a part of 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.

[0058] This application claims priority based on Japanese Patent Application No. 2022-197203 filed with the Japan Patent Office on December 9, 2022, and all the contents of the application are incorporated into this specification by reference.

Claims

1. A pilot cover unit, wherein: The pilot cover unit is mounted on a control valve having a valve housing penetrating therethrough and having a spool hole formed therein, and a spool is slidably received in the spool hole. The pilot cover unit includes a first pilot cover, which is mounted on the valve housing and faces one end of the slide valve hole, and defines a first pilot chamber between the first pilot cover and the valve housing. The first pilot cover has: a receiving hole capable of receiving a portion of a solenoid valve that controls the pressure of a pilot fluid supplied to the first pilot chamber; a pilot passage, which is in communication with the receiving hole and guides the pilot fluid decompressed by the solenoid valve to the first pilot chamber; a drainage passage communicating with the receiving hole and guiding the pilot fluid discharged from the solenoid valve, In the receiving hole, the solenoid valve can be installed, and a plug can be installed to replace the solenoid valve. In a state where the plug is mounted in the housing hole, the pilot passage and the drainage passage are always communicated with each other via a plug passage formed in the plug.

2. The pilot cover unit according to claim 1, wherein: The pilot cover unit further includes a second pilot cover, which is mounted on the valve housing and faces the other end of the slide valve hole, and defines a second pilot chamber between the second pilot cover and the valve housing. The valve housing has: a first port which opens at the spool hole and is disposed adjacent to the second pilot chamber and communicates with the atmosphere; a second port which opens at the spool hole and is disposed adjacent to the first pilot chamber and has a higher pressure than the first port, A plug may be mounted on the first pilot cover in place of the solenoid valve.

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