Valve unit

Abstract

Reduce the number of parts required for the additional control valve gear. [Solution] The valve unit 100 comprises a control valve 10, an electromagnetic proportional valve 20, a first housing 30, a cap 40, a first primary pressure passage 41 that guides primary pressure hydraulic fluid to the electromagnetic proportional valve 20, a first secondary pressure passage 42 that guides hydraulic fluid guided from the first primary pressure passage 41 and reduced to secondary pressure by the electromagnetic proportional valve 20 to a pilot chamber 11, and a first drain passage 43 that guides hydraulic fluid discharged from the first secondary pressure passage 42 through the electromagnetic proportional valve 20. The first housing 30 has an installation surface 30a to which an add-on valve 200 equipped with an additional control valve 60 driven by hydraulic fluid guided to a pilot chamber 61 and an electromagnetic proportional valve 80 that controls the pressure of the hydraulic fluid guided to the pilot chamber 61 can be attached, and the first primary pressure passage 41 and the first drain passage 43 are configured to open to the installation surface 30a of the first housing 30.

Description

Technical Field

[0001] The present invention relates to a valve unit.

Background Art

[0002] Patent Document 1 discloses a multi-control valve unit in which an electromagnetic proportional valve for controlling the pilot pressure of a control valve is attached to a cover of a housing that houses the spool of the control valve.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] An add-on valve (additional control valve device) may be attached to the valve unit. For example, the add-on valve is attached for the attachment after replacement when replacing an attachment in a construction machine such as an excavator, and there is an add-on valve of a hydraulic pilot type.

[0005] However, in the case of an add-on valve of the hydraulic pilot type, a hydraulic pilot valve for generating the pilot pressure of the add-on valve, a pump for supplying pressure oil to the hydraulic pilot valve, and connecting pipes thereof are required, and the number of parts for the add-on valve increases.

[0006] The present invention has been made in view of such problems, and an object thereof is to reduce the number of parts for an additional control valve device.

Means for Solving the Problems

[0007] The present invention relates to a valve unit comprising: a control valve driven by a working fluid introduced into a pilot chamber; an electromagnetic proportional valve for controlling the pressure of the working fluid introduced into the pilot chamber; a monoblock structure first housing provided with a plurality of control valves; a cap attached to the first housing and provided with a pilot chamber and an electromagnetic proportional valve; a first primary pressure passage for introducing working fluid at primary pressure to the electromagnetic proportional valve; a first secondary pressure passage for introducing working fluid introduced from the first primary pressure passage and reduced to secondary pressure by the electromagnetic proportional valve to the pilot chamber; and a first drain passage for introducing working fluid discharged from the first secondary pressure passage through the electromagnetic proportional valve, wherein the first housing has an installation surface to which an additional control valve device provided with an additional control valve driven by a working fluid introduced into a pilot chamber and an electromagnetic proportional valve for controlling the pressure of the working fluid introduced into the pilot chamber can be installed, and the first primary pressure passage and the first drain passage open to the installation surface of the first housing.

[0008] According to this invention, since the first primary pressure passage opens to the mounting surface of the first housing, it becomes possible to use a common pump between the additional control valve device and the valve unit, which are equipped with an electromagnetic proportional valve and do not require a hydraulic pilot valve, and also eliminates the need for connecting piping between the additional control valve device and the pump. Furthermore, since the first drain passage also opens to the mounting surface of the first housing, it becomes possible to use a common drain piping between the additional control valve device and the valve unit.

[0009] Furthermore, the present invention provides an additional control valve device having a second housing which is attached to the first housing and which is provided with an additional control valve and a solenoid proportional valve for the additional control valve device, and further comprising a cover which is attached to the second housing of the additional control valve device, the pilot chamber of the additional control valve having a first pilot chamber and a second pilot chamber provided on each side of the additional control valve, the solenoid proportional valve of the additional control valve device having a first solenoid proportional valve and a second solenoid proportional valve which control the pressure of the working fluid led to the first pilot chamber and the second pilot chamber, respectively, the second housing having two second primary pressure passages which lead the working fluid at primary pressure to the first solenoid proportional valve and the second solenoid proportional valve, respectively, and the working fluid led from each of the two second primary pressure passages which is controlled by the first solenoid proportional valve and the second solenoid proportional valve to secondary pressure The device has two second secondary pressure passages that guide depressurized working fluid to a first pilot chamber and a second pilot chamber, two second drain passages that guide working fluid discharged from each of the two second secondary pressure passages through a first solenoid proportional valve and a second solenoid proportional valve, a primary pressure through-hole that communicates with an opening of a first primary pressure passage formed on the installation surface when attached to the first housing, and a drain through-hole that communicates with an opening of a first drain passage formed on the installation surface when attached to the first housing, and the cover has a primary pressure connecting passage that connects the primary pressure through-hole and the two second primary pressure passages when attached to the second housing, and a drain connecting passage that connects the drain through-hole and the two second drain passages when attached to the second housing.

[0010] According to this invention, it is not necessary to provide a second primary pressure passage and a second drain passage in the second housing to connect the first solenoid proportional valve and the second solenoid proportional valve. Therefore, the second housing can be made smaller by the amount by which these passages no longer need to be formed. Accordingly, by improving the layoutability of the valve unit and the entire additional control valve device through the miniaturization of the second housing, the layoutability of the valve unit can be improved.

[0011] Furthermore, the present invention is characterized in that the cap has a first cap provided on a first side surface of the first housing and a second cap provided on a second side surface of the first housing opposite to the first side surface, and the first primary pressure passage and the first drain passage each have a first passage formed in the first cap, a second passage formed in the second cap, a third passage formed in the first housing that connects the first passage and the second passage, and a branch passage branching off from the third passage, and the branch passages of the first primary pressure passage and the first drain passage each open to the installation surface of the first housing.

[0012] According to this invention, it is possible to make it less likely for an imbalance to occur in the supply balance of the working fluid between the valve unit and the additional control valve device, and it is also possible to make it less likely for an imbalance to occur in the discharge balance of the working fluid between the first cap and the second cap. [Effects of the Invention]

[0013] These inventions make it possible to reduce the number of parts required for additional control valve devices. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic diagram of a valve unit according to an embodiment of the present invention. [Figure 2] This figure shows the main parts of a control valve and a solenoid proportional valve according to an embodiment of the present invention. [Figure 3] This figure shows the main components of a hydraulic circuit according to an embodiment of the present invention. [Figure 4] This is a cross-sectional view of the add-on valve along line AA in Figure 1. [Figure 5] This is a diagram showing a modified example of an add-on valve. [Figure 6] This is a cross-sectional view of a modified example along line BB in Figure 5. [Figure 7] This diagram shows a modified valve unit. [Modes for carrying out the invention]

[0015] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0016] The valve unit 100 described below is used in a working machine such as a power shovel. Hereinafter, the case where the working machine is a power shovel will be described, but the working machine may be another working machine such as a wheel loader. Further, hydraulic oil is used as the working fluid, but the working fluid may be another fluid such as working water.

[0017] As shown in FIGS. 1 to 3, the valve unit 100 includes a control valve 10 driven by hydraulic oil introduced into a pilot chamber 11, an electromagnetic proportional valve 20 that controls the pressure of the hydraulic oil introduced into the pilot chamber 11, a first housing 30 having a monoblock structure in which a plurality of control valves 10 are provided, and a cap 40 attached to the first housing 30 and provided with the pilot chamber 11 and the electromagnetic proportional valve 20.

[0018] As shown in FIG. 1, an add-on valve 200 as an additional control valve device attached for the attachment after attachment replacement can be attached to the valve unit 100 during attachment replacement in a power shovel, and the first housing 30 has an installation surface 30a to which the add-on valve 200 can be attached. The add-on valve 200 will be described later.

[0019] As shown in FIG. 2, the control valve 10 includes a pilot chamber 11, a spool 12 driven by the pressure of hydraulic oil introduced into the pilot chamber 11, a rod 13 coupled to one end of the spool 12 and extending into the pilot chamber 11, a spring 14 accommodated in the pilot chamber 11 and applying a biasing force to one end of the spool 12, and spring receiving members 15, 16 accommodated in the pilot chamber 11 so as to be slidable along the outer periphery of the rod 13 with the spring 14 interposed therebetween.

[0020] The spool 12 of the control valve 10 is slidably incorporated into the first housing 30. The first housing 30 has an installation surface 30b on which the cap 40 is installed, and a housing hole 30c for the spool 12 opens on the installation surface 30b of the first housing 30.

[0021] The cap 40 has an attachment surface 40a to the first housing 30, and is fixed to the first housing 30 by a bolt (not shown) with the attachment surface 40a abutted against the installation surface 30b. The pilot chamber 11 opens on the attachment surface 40a of the cap 40, and the pilot chamber 11 is defined by attaching the cap 40 to the first housing 30.

[0022] The cap 40 has an installation surface 40b on which the electromagnetic proportional valve 20 is installed, and a housing chamber 44 formed on the installation surface 40b for housing the valve body 21 of the electromagnetic proportional valve 20. The installation surface 40b is located on the opposite side of the attachment surface 40a, and the housing chamber 44 extends along the axial direction of the control valve 10. The electromagnetic proportional valve 20 is attached to the installation surface 40b with the valve body 21 inserted into the housing chamber 44, and the valve body 21 is slidably housed in the housing chamber 44.

[0023] The electromagnetic proportional valve 20 has, in addition to the valve body 21 constituted by an axial member, a solenoid 22 that applies a thrust to the valve body 21, and a coil spring 23 as a biasing member that applies a biasing force to the valve body 21 in a direction opposite to the thrust of the solenoid 22.

[0024] The solenoid 22 is fixed to the cap 40 by a bolt. The solenoid 22 is an actuator that advances and retreats the push rod 22a by the supplied control current, and one end of the valve body 21 is fixed to the push rod 22a. The coil spring 23 contracts according to the movement amount of the valve body 21, and biases the valve body 21 toward the solenoid 22 by applying a biasing force to the valve body 21 according to the contraction amount (elastic deformation amount) from the natural length.

[0025] The electromagnetic proportional valve 20 controls the secondary pressure (pilot pressure) output to the pilot chamber 11 according to the control current supplied to the solenoid 22. A proportional pressure reducing valve that increases the secondary pressure as the current supplied to the solenoid 22 increases can be used for the electromagnetic proportional valve 20. As shown in FIGS. 1 and 3, a plurality of electromagnetic proportional valves 20 are provided on the cap 40 corresponding to the plurality of control valves 10 provided on the first housing 30.

[0026] As shown in Figures 1-3, the valve unit 100 further includes a first primary pressure passage 41 that guides hydraulic fluid at primary pressure to the solenoid proportional valve 20, a first secondary pressure passage 42 that guides hydraulic fluid, which is guided from the first primary pressure passage 41 and reduced to secondary pressure by the solenoid proportional valve 20, to the pilot chamber 11 (see Figures 2 and 3), and a first drain passage 43 that guides hydraulic fluid discharged from the first secondary pressure passage 42 through the solenoid proportional valve 20.

[0027] As shown in Figure 1, the first primary pressure passage 41 has a main primary pressure passage 41a that extends in the direction in which the multiple solenoid proportional valves 20 are aligned, and the first drain passage 43 has a main drain passage 43a that extends in the direction in which the multiple solenoid proportional valves 20 are aligned. The main primary pressure passage 41a and the main drain passage 43a are formed in the cap 40 and open to the first side surface 40c (upper side surface in Figure 1) and the second side surface 40d (lower side surface in Figure 1) opposite to the first side surface 40c of the cap 40.

[0028] As shown in Figures 2 and 3, the first primary pressure passage 41 further has a secondary primary pressure passage 41b, one end of which is connected to the main primary pressure passage 41a and the other end of which is connected to the solenoid proportional valve 20, and the first drain passage 43 further has a secondary drain passage 43b, one end of which is connected to the main drain passage 43a and the other end of which is connected to the solenoid proportional valve 20. The secondary primary pressure passage 41b and the secondary drain passage 43b are formed in the cap 40 and multiple passages are provided corresponding to each solenoid proportional valve 20. The cap 40 also has a first secondary pressure passage 42, and multiple first secondary pressure passages 42 are provided corresponding to each solenoid proportional valve 20.

[0029] The electromagnetic proportional valve 20 has an input port P1 through which primary pressure hydraulic fluid is introduced from a first primary pressure passage 41, an output port P2 through which secondary pressure hydraulic fluid is introduced from a first secondary pressure passage 42, and a drain port P3 through which drain (discharged hydraulic fluid) is introduced from a first drain passage 43. The passages 41 to 43 communicate with the housing chamber 44 through ports P1 to P3.

[0030] As shown in Figure 3, the electromagnetic proportional valve 20 operates between a closed position C, where communication between the input port P1 and the output port P2 is blocked and communication between the output port P2 and the drain port P3, and an open position O, where communication between the input port P1 and the output port P2 is connected and communication between the output port P2 and the drain port P3 is blocked. In the intermediate position M between the closed position C and the open position O, the input port P1 communicates with both the output port P2 and the drain port P3 through a throttle.

[0031] The electromagnetic proportional valve 20 controls the secondary pressure (pilot pressure) output to the pilot chamber 11 by adjusting the communication between the input port P1 and the drain port P3 and the output port P2, based on the balance (equilibrium) of the thrust from the solenoid 22, the biasing force from the coil spring 23, and the thrust from the secondary pressure relative to the valve body 21 (see Figure 2).

[0032] A pump P, which is the fluid pressure supply source for the valve unit 100, is connected to the first housing 30. The pump P draws hydraulic fluid from the tank T, pressurizes the drawn hydraulic fluid, and discharges it. The pump P is connected to the first housing 30 via a connecting pipe 51. The first housing 30 has a first supply passage 31 that guides the hydraulic fluid to be supplied to the actuator to the control valve 10, and the first supply passage 31 communicates with the connecting pipe 51 through an inlet opening 32 that opens on the outer surface of the first housing 30. The first supply passage 31 is branched and connected to each control valve 10, and the hydraulic fluid from the pump P is guided to each control valve 10 in parallel.

[0033] The control valve 10A (the uppermost control valve 10 in Figure 3), provided for the hydraulic cylinder 150, switches the supply and discharge of hydraulic fluid to the rod chamber 150a, which serves as the high-load pressure chamber of the hydraulic cylinder 150. The control valve 10A and hydraulic cylinder 150 are just one example of a combination of a control valve 10 and an actuator; other control valves 10 are also provided for actuators not shown. The actuator may be a hydraulic motor or the like.

[0034] As shown in Figure 1, the cap 40 has a first cap 40A provided on one of the installation surfaces 30ba (first side surface) of the first housing 30 (left side in Figure 1), and a second cap 40B provided on the other installation surface 30bb (second side surface) of the first housing 30 (right side in Figure 1). The first primary pressure passage 41 and the first drain passage 43 are further configured as follows.

[0035] The first primary pressure passage 41 further has a primary pressure connecting passage 41c (third passage) that connects and communicates the main primary pressure passages 41a (first passage, second passage) formed in each of the caps 40A and 40B, and the first drain passage 43 further has a drain connecting passage 43c (third passage) that connects and communicates the main drain passages 43a (first passage, second passage) formed in each of the caps 40A and 40B.

[0036] The primary pressure connection passage 41c and the drain connection passage 43c are formed across the first housing 30 and the caps 40A and 40B, and are located on the side opposite to the installation surface 30a of the first housing 30 in the direction in which the multiple electromagnetic proportional valves 20 are lined up.

[0037] The primary pressure connection passage 41c has a cap portion 41ca formed on each of the caps 40A and 40B, and a housing portion 41cb formed on the first housing 30. The cap portion 41ca branches off from the main primary pressure passage 41a, extends from the main primary pressure passage 41a toward the first housing 30, and opens to the mounting surface 40a. The housing portion 41cb opens to the mounting surfaces 30ba and 30bb to which the caps 40A and 40B are attached, and communicates with the cap portion 41ca formed on each of the caps 40A and 40B. Specifically, the housing portion 41cb of the primary pressure connection passage 41c corresponds to the third passage of the first primary pressure passage 41.

[0038] The drain connection passage 43c has a cap portion 43ca formed on each of the caps 40A and 40B, and a housing portion 43cb formed on the first housing 30. The cap portion 43ca branches off from the main drain passage 43a, extends from the main drain passage 43a toward the first housing 30, and opens to the mounting surface 40a. The housing portion 43cb opens to the mounting surfaces 30ba and 30bb on which the caps 40A and 40B are attached, and connects to the cap portion 43ca formed on each of the caps 40A and 40B. Specifically, the housing portion 43cb of the drain connection passage 43c corresponds to the third passage of the first drain passage 43.

[0039] The first primary pressure passage 41 further has a primary pressure communication passage 41d that communicates with the main primary pressure passage 41a formed in the first cap 40A and opens to the installation surface 30a of the first housing 30, and the first drain passage 43 further has a drain communication passage 43d that communicates with the main drain passage 43a formed in the first cap 40A and opens to the installation surface 30a of the first housing 30.

[0040] The primary pressure communication passage 41d and the drain communication passage 43d are provided across the first cap 40A and the first housing 30, and are located on the installation surface side (upper side in Figure 1) of the first housing 30 in the direction in which the multiple electromagnetic proportional valves 20 are lined up.

[0041] The primary pressure communication passage 41d has a cap portion 41da provided on the first cap 40A and a housing portion 41db provided on the first housing 30. The cap portion 41da branches off from the main primary pressure passage 41a, extends from the main primary pressure passage 41a toward the first housing 30, and opens to the mounting surface 40a. The cap portion 41da is provided on the mounting surface 30a side (upper side in Figure 1) than all of the valve bodies 21 of the multiple electromagnetic proportional valves 20.

[0042] The housing portion 41db opens to one of the mounting surfaces 30ba, extends from the mounting surface 30ba to the center of the first housing 30, and then extends along the height direction of the valve unit 100 (a direction perpendicular to the up, down, left, and right directions in Figure 1) to the same height as the drain communication passage 43d. The housing portion 41db then extends further toward the mounting surface 30a and opens to the mounting surface 30a, forming an outlet opening 30d for the hydraulic fluid of primary pressure through the first primary pressure passage 41 on the mounting surface 30a. Note that the height direction of the valve unit 100 does not have to be vertical.

[0043] The drain communication passage 43d has a cap portion 43da provided on the first cap 40A and a housing portion 43db provided on the first housing 30. The cap portion 43da branches off from the main drain passage 43a, extends from the main drain passage 43a toward the first housing 30, and opens to the mounting surface 40a. The cap portion 43da communicates with the main drain passage 43a at the same point as the electromagnetic proportional valve 20 located closest to the mounting surface 30a (upper side in Figure 1).

[0044] The housing portion 43db opens to one of the installation surfaces 30ba, extends from the one installation surface 30ba to the center of the first housing 30, and then extends toward the installation surface 30a and opens to the installation surface 30a. By opening to the installation surface 30a, the housing portion 43db forms an outlet opening 30e for the drain through the first drain passage 43 on the installation surface 30a.

[0045] The outlet opening 30e is located on the side of the second cap 40B that is located on the side of the outlet opening 30d. The outlet opening 30d is located in the center of the first housing 30 and closer to the first cap 40A, and the outlet opening 30e is located in the center of the first housing 30 and closer to the second cap 40B. The first primary pressure passage 41 opens to the installation surface 30a of the first housing 30 through the outlet opening 30d, and the first drain passage 43 opens to the installation surface 30a of the first housing 30 through the outlet opening 30e.

[0046] In the valve unit 100, one end (lower end in Figure 1) of the main primary pressure passage 41a of the first cap 40A forms a hydraulic fluid inlet opening 47, and the other end (upper end in Figure 1) of the main primary pressure passage 41a of caps 40A and 40B, and both ends of the main drain passages 43a of caps 40A and 40B, are sealed by plugs PG.

[0047] As shown in Figure 3, a branch pipe 52, which branches off from the connecting pipe 51, is connected to the inlet opening 47, and the pump P communicates with the main primary pressure passage 41a of the first cap 40A through the branch pipe 52 and the inlet opening 47. A pressure reducing valve (not shown) is provided in the branch pipe 52, and the hydraulic fluid supplied from the pump P to the branch pipe 52 is depressurized by the pressure reducing valve and then supplied to the main primary pressure passage 41a of the first cap 40A. By supplying hydraulic fluid to the main primary pressure passage 41a of the first cap 40A, the pump P also supplies hydraulic fluid to the main primary pressure passage 41a of the second cap 40B (see Figure 1) through the primary pressure connecting passage 41c. For this reason, a plug PG is installed in place of the inlet opening 47 on the other end of the first housing 30 (right side in Figure 1). Alternatively, instead of pump P, a pump (main pump) that supplies hydraulic fluid to the actuator through the first supply passage 31 and the control valve 10, and a pump (sub-pump) that supplies hydraulic fluid to the pilot chamber 11 through the main primary pressure passage 41a of the first cap 40A and the electromagnetic proportional valve 20 may be provided.

[0048] Next, we will explain the add-on valve 200 in more detail.

[0049] Figure 4 is a cross-sectional view of the add-on valve 200 along line AA in Figure 1. As shown in Figure 4, the add-on valve 200 is configured as a valve equipped with an additional control valve 60 driven by hydraulic fluid led to a pilot chamber 61 and an electromagnetic proportional valve 80 that controls the pressure of the hydraulic fluid led to the pilot chamber 61, and has a second housing 90 that is mounted on the first housing 30 and is equipped with the additional control valve 60 and the electromagnetic proportional valve 80. As shown in Figure 1, the valve unit 100 further comprises a cover 5 that is mounted on the second housing 90, and the second housing 90 has a mounting surface 90a to the first housing 30 and an installation surface 90b to which the cover 5 is mounted.

[0050] As shown in Figure 4, the additional control valve 60 is incorporated inside the second housing 90 and controls the operation of an actuator for driving the replacement attachment in the power shovel. The pilot chamber 61 of the additional control valve 60 has a first pilot chamber 61A and a second pilot chamber 61B, which are provided on each side of the additional control valve 60. The first pilot chamber 61A is formed in a cylindrical pilot chamber forming member M1, and the second pilot chamber 61B is formed in a cylindrical pilot chamber forming member M2. The open ends of the pilot chamber forming members M1 and M2 are sealed by plugs (not shown).

[0051] The solenoid proportional valves 80 of the add-on valve 200 have a first solenoid proportional valve 80A and a second solenoid proportional valve 80B that control the pressure of the hydraulic fluid led to the first pilot chamber 61A and the second pilot chamber 61B, respectively. Pilot pressure is led to the first pilot chamber 61A through the first solenoid proportional valve 80A, and pilot pressure is led to the second pilot chamber 61B through the second solenoid proportional valve 80B. The solenoid proportional valves 80A and 80B are installed on the lower surface 90c (lower side in Figure 4) of the second housing 90 and are arranged side by side along the direction in which the spool 62 extends (left-right direction in Figure 4). The solenoid proportional valves 80A and 80B are located at both ends (left and right ends in Figure 4) of the lower surface 90c in the direction in which the spool 62 extends. The first pilot chamber 61A houses a spring 69 that applies a biasing force to one end of the spool 62, and the position of the spool 62 is switched by the balance between the thrust from the pilot pressure in the respective pilot chambers 61A and 61B and the biasing force of the spring 69.

[0052] The additional control valve 60 includes a spool 62 whose position can be switched between a plurality of switching positions, and a housing hole 63 formed in the second housing 90 that slidably accommodates the spool 62. The housing hole 63 has an annular recess 64 in the center, pump ports 65a, 65b provided on the outside of the annular recess 64, supply ports 66a, 66b provided on the outside of the annular recess 64 and the pump ports 65a, 65b, operating ports 67a, 67b provided on the outside of the supply ports 66a, 66b, and discharge ports 68a, 68b provided on the outside of the operating ports 67a, 67b. In this embodiment, the discharge ports 68a, 68b are formed by tank passages 92a, 92b.

[0053] Pump ports 65a and 65b are connected to pump P (see Figure 3) through a second supply passage (not shown). The second supply passage can be connected to the first supply passage 31 (see Figure 3) by forming an opening for the first supply passage 31 (see Figure 3) in the installation surface 30a (see Figure 1) of the first housing 30. Pump ports 65a and 65b may also be connected to a pump other than pump P through the second supply passage. Tank passages 92a and 92b open to the outer surface of the second housing 90 and are connected to tank T (see Figure 3) through a return pipe. Tank passages 92a and 92b may communicate with a tank passage (not shown) of the first housing 30.

[0054] The additional control valve 60 further comprises a valve housing hole 70 formed perpendicular to the housing hole 63, and a compensator valve 71 slidably housed in the valve housing hole 70. The annular recess 64 and the supply ports 66a and 66b communicate through the compensator valve 71. The degree to which the compensator valve 71 communicates these ports changes according to the pressure of the hydraulic fluid acting on the compensator valve 71.

[0055] The additional control valve 60 is formed in the second housing 90 and further has relief passages 93a, 93b that connect the tank passages 92a, 92b and the operating ports 67a, 67b. Relief valves 72, 73 are provided in the relief passages 93a, 93b, which define the maximum pressure (relief pressure) of the hydraulic fluid in the operating ports 67a, 67b. The relief valves 72, 73 open when the pressure in the operating ports 67a, 67b exceeds a preset relief pressure. As a result, hydraulic fluid is discharged from the operating ports 67a, 67b through the relief valves 72, 73 and the tank passages 92a, 92b to the tank T (see Figure 3), preventing excessive pressure rise in the operating ports 67a, 67b and the actuator.

[0056] The additional control valve 60 has three switching positions: a neutral position where the spool 62 is in a neutral state (as shown in Figure 4), a first position where the spool 62 is located closer to the first actuator port 91a (right side in Figure 4) compared to the neutral position, and a second position where the spool 62 is located closer to the second actuator port 91b (left side in Figure 4) compared to the neutral position.

[0057] In the neutral position, the operating ports 67a and 67b are isolated from the supply ports 66a and 66b and the discharge ports 68a and 68b by the spool 62. When pilot pressure is introduced to the first pilot chamber 61A and the spool 62 moves to the first actuator port 91a side (right side in Figure 4) to reach the first position, the annular recess 64 and the pump port 65a communicate, and hydraulic fluid is introduced to the supply ports 66a and 66b. The hydraulic fluid introduced to the supply port 66a is supplied to the actuator through the operating port 67a and the first actuator port 91a, which communicate with the supply port 66a. On the other hand, in the first position, the operating port 67b and the discharge port 68b communicate, and hydraulic fluid is discharged from the actuator to the tank T (see Figure 3) through the tank passage 92b which forms the second actuator port 91b, the operating port 67b, and the discharge port 68b. In the second position, the situation is the same as in the first position. In the second position, pilot pressure is directed to the second pilot chamber 61B, and the spool 62 moves towards the second actuator port 91b side (left side in Figure 4) to reach the second position.

[0058] The second housing 90 further includes a second primary pressure passage 94 that leads the primary pressure hydraulic fluid to the solenoid proportional valve 80 of the add-on valve 200, a second secondary pressure passage 95 that leads the hydraulic fluid, which is led from the second primary pressure passage 94 and reduced to secondary pressure by the solenoid proportional valve 80, to the pilot chamber 61, and a second drain passage 96 that leads the hydraulic fluid discharged from the second secondary pressure passage 95 through the solenoid proportional valve 80.

[0059] The second primary pressure passage 94 has a main primary pressure passage 94a that extends in the direction in which the solenoid proportional valves 80A and 80B are aligned, and the second drain passage 96 has a main drain passage 96a that extends in the direction in which the solenoid proportional valves 80A and 80B are aligned. The main primary pressure passage 94a and the main drain passage 96a open to the first side surface 90d (left side surface in Figure 4) and the second side surface 90e (lower side surface in Figure 1) opposite to the first side surface 90d of the second housing 90. The openings on the respective sides 90d and 90e of the main primary pressure passage 94a and the main drain passage 96a are sealed by plugs (not shown).

[0060] The solenoid proportional valve 80, like the solenoid proportional valve 20 (see Figure 2), has an input port P1, an output port P2, and a drain port P3. The input port P1 of the solenoid proportional valve 80 is connected to the main primary pressure passage 94a through a secondary primary pressure passage 94b, which is located behind the valve body 81 of the solenoid proportional valve 80 in Figure 4, that is, on the installation surface 90b (see Figure 1) side relative to the valve body 81. The drain port P3 of the solenoid proportional valve 80 is connected to the main drain passage 96a through a secondary drain passage 96b of the second drain passage 96.

[0061] The second secondary pressure passage 95 connects the output port P2 of the solenoid proportional valve 80 to the pilot chamber 61. The second secondary pressure passage 95 has a first passage 95a that connects to the output port P2 from behind the valve body 81 in Figure 4, and a second passage 95b that extends from the first passage 95a toward the pilot chamber 61, then extends toward the spool 62 and opens into the housing hole 63. The second passage 95b connects to the pilot chamber 61 through the gap between the spool 62 and the housing hole 63. The second secondary pressure passage 95 is composed of multiple passages formed by drilling from the outer surface of the second housing 90. The multiple openings that the second secondary pressure passage 95 has on the outer surface of the second housing 90 are sealed by plugs (not shown).

[0062] The second secondary pressure passage 95 includes a second secondary pressure passage 95A that connects the first solenoid proportional valve 80A and the first pilot chamber 61A, and a second secondary pressure passage 95B that connects the second solenoid proportional valve 80B and the second pilot chamber 61B. Therefore, the hydraulic fluid at secondary pressure (pilot pressure) is supplied from the first solenoid proportional valve 80A to the first pilot chamber 61A, and the hydraulic fluid at secondary pressure is supplied from the second solenoid proportional valve 80B to the second pilot chamber 61B.

[0063] The second housing 90, when attached to the first housing 30 (see Figure 1), further includes a primary pressure through-hole 97 communicating with the outlet opening 30d (see Figure 1) of the first primary pressure passage 41 formed in the installation surface 30a (see Figure 1) of the first housing 30, a drain through-hole 98 communicating with the outlet opening 30e (see Figure 1) of the first drain passage 43 formed in the installation surface 30a (see Figure 1) of the first housing 30 (see Figure 1), a primary pressure connecting passage 99A connecting the primary pressure through-hole 97 and the second primary pressure passage 94, and a drain connecting passage 99B connecting the drain through-hole 98 and the second drain passage 96.

[0064] The primary pressure penetration hole 97 and the drain penetration hole 98 are sealed on the installation surface 90b (see Figure 1) side by the cover 5 (see Figure 1). The cover 5 can be attached to the installation surface 30a of the first housing 30 if the add-on valve 200 cannot be attached to the valve unit 100, and when attached to the first housing 30, it seals the outlet openings 30d and 30e. For this reason, a separate cover for the add-on valve 200 is not required, and if the add-on valve 200 cannot be attached to the valve unit 100, the cover 5 can be attached to the first housing 30, which also serves as a measure to prevent loss.

[0065] As shown in Figure 4, the primary pressure connection passage 99A and the drain connection passage 99B are formed between the two solenoid proportional valves 80 and extend in the vertical direction (up and down direction in Figure 4) of the add-on valve 200. The primary pressure connection passage 99A connects the primary pressure through-hole 97 and the second primary pressure passage 94 at a position where the primary pressure through-hole 97 and the second primary pressure passage 94 overlap when viewed along the vertical direction of the add-on valve 200 (i.e., at a position where they intersect when viewed from above). The same applies to the drain connection passage 99B.

[0066] In the valve unit 100 configured as described above, the first primary pressure passage 41 opens to the installation surface 30a of the first housing 30 (see Figure 1). This allows for the common use of the pump P (see Figure 3) between the add-on valve 200, which is equipped with an electromagnetic proportional valve 80 and does not require a hydraulic pilot valve, and the valve unit 100. This also eliminates the need for connecting piping between the add-on valve 200 and the pump P. Furthermore, the first drain passage 43 also opens to the installation surface 30a of the first housing 30 (see Figure 1), allowing for the common use of drain piping between the add-on valve 200 and the valve unit 100. Consequently, the number of parts required for the add-on valve 200 can be reduced.

[0067] The add-on valve 200 may be configured as follows:

[0068] Figure 5 shows a modified example of the add-on valve 200, and Figure 6 is a cross-sectional view of the modified example along line BB in Figure 5. As shown in Figure 5, in this example, the second housing 90 has, as a second primary pressure passage 94, two second primary pressure passages 94A, 94B that lead to the first solenoid proportional valve 80A and the second solenoid proportional valve 80B, respectively, as a second primary pressure passage 94, two second secondary pressure passages 95A, 95B that lead the hydraulic fluid, which is led from each of the two second primary pressure passages 94A, 94B and reduced to secondary pressure by the first solenoid proportional valve 80A and the second solenoid proportional valve 80B, to the first pilot chamber 61A and the second pilot chamber 61B, as a second secondary pressure passage 95, two second drain passages 96A, 96B that lead the hydraulic fluid discharged from each of the two second secondary pressure passages 95A, 95B through the first solenoid proportional valve 80A and the second solenoid proportional valve 80B.

[0069] The second primary pressure passage 94A, the second secondary pressure passage 95A, and the second drain passage 96A are provided for the first solenoid proportional valve 80A, while the second primary pressure passage 94B, the second secondary pressure passage 95B, and the second drain passage 96B are provided for the second solenoid proportional valve 80B. In this example, the first solenoid proportional valve 80A is installed on the first side surface 90d of the second housing 90, and the second solenoid proportional valve 80B is installed on the second side surface 90e of the second housing 90. The solenoid proportional valves 80A and 80B are located below the spool 62 and the tank passages 92a and 92b (lower side in Figure 5).

[0070] The second primary pressure passages 94A and 94B are located behind the valve body 81 of the solenoid proportional valves 80A and 80B in Figure 5, that is, on the side of the installation surface 90b (see Figure 1) relative to the valve body 81, and open to the installation surface 90b. The second primary pressure passages 94A and 94B extend from the installation surface 90b toward the solenoid proportional valves 80A and 80B and connect to the input port P1 of the solenoid proportional valves 80A and 80B.

[0071] The second secondary pressure passages 95A and 95B connect the output port P2 of the solenoid proportional valves 80A and 80B to the pilot chambers 61A and 61B. In this example, the second secondary pressure passages 95A and 95B have a first passage 95a that communicates with the output port P2 from behind the valve body 81 of the solenoid proportional valves 80A and 80B in Figure 4, and a second passage 95b that extends from the first passage 95a toward the spool 62 and opens into the housing hole 63. The second passage 95b communicates with the pilot chambers 61A and 61B through the gap between the spool 62 and the housing hole 63.

[0072] The second drain passages 96A and 96B open to the installation surface 90b (see Figure 1), extend from the installation surface 90b toward the mounting surface 90a (see Figure 1), and are adjacent to the valve bodies 81 of the solenoid proportional valves 80A and 80B from the inside of the second housing 90. The drain port P3 is connected to the second drain passages 96A and 96B through the sub-drain passages 96b of the second drain passages 96A and 96B. The second drain passages 96A and 96B extend further downward (towards the bottom in Figure 5) from the position adjacent to the valve bodies 81 of the solenoid proportional valves 80A and 80B and open to the bottom surface 90c of the second housing 90. The openings of the second drain passages 96A and 96B formed on the bottom surface 90c are connected to the tank T through the drain piping.

[0073] In this example, in the second housing 90, the second primary pressure passage 94 and the primary pressure through-hole 97 are not connected to each other, nor are the second drain passage 96 and the drain through-hole 98 connected to each other. In this example, as will be described below, the second primary pressure passage 94 and the primary pressure through-hole 97 are connected through the cover 5, and the second drain passage 96 and the drain through-hole 98 are also connected through the cover 5.

[0074] As shown in Figure 6, when the cover 5 is attached to the second housing 90, it has a primary pressure connection passage 6 that connects the primary pressure through hole 97 to two second primary pressure passages 94, and a drain connection passage 7 that connects the drain through hole 98 to two second drain passages 96.

[0075] The cover 5 has a mounting surface 5a that is attached to the mounting surface 90b of the second housing 90, and the mounting surface 5a has an inlet opening 6a for the primary pressure connection passage 6 and an inlet opening 7a for the drain connection passage 7. The primary pressure connection passage 6 is connected to the primary pressure through-hole 97 through the inlet opening 6a, and the drain connection passage 7 is connected to the drain through-hole 98 through the inlet opening 7a.

[0076] The primary pressure connection passage 6 extends from the inlet opening 6a toward the opposite side of the second housing 90, then extends downward to the same height as the valve bodies 81 of the solenoid proportional valves 80A and 80B, and then extends again toward the opposite side of the second housing 90, passing below the drain connection passage 7. The primary pressure connection passage 6 then branches and extends toward the first solenoid proportional valve 80A and the second solenoid proportional valve 80B, respectively, and then extends toward the mounting surface 5a, opening onto the mounting surface 5a and forming outlet openings 6b and 6c. The primary pressure connection passage 6 connects to the second primary pressure passage 94A through outlet opening 6b and to the second primary pressure passage 94B through outlet opening 6c.

[0077] The drain connection passage 7 extends from the inlet opening 7a toward the opposite side of the second housing 90, then branches out toward the first solenoid proportional valve 80A and the second solenoid proportional valve 80B, respectively, and further extends downward to the same height as the valve bodies 81 of the solenoid proportional valves 80A and 80B. The drain connection passage 7 then extends toward the mounting surface 5a and opens toward the mounting surface 5a, forming outlet openings 7b and 7c. The drain connection passage 7 connects to the second drain passage 96A through outlet opening 7b and to the second drain passage 96B through outlet opening 7c.

[0078] In this example, it is not necessary to provide a second primary pressure passage 94 and a second drain passage 96 in the second housing 90 to connect the first solenoid proportional valve 80A and the second solenoid proportional valve 80B. Therefore, the second housing 90 can be made smaller by the amount of the portion R (see Figure 5) where these passages 94 and 96 do not need to be formed. Consequently, by improving the overall layoutability of the valve unit 100 and the add-on valve 200 through the miniaturization of the second housing 90, the layoutability of the valve unit 100 can be improved.

[0079] In this example, the solenoid proportional valves 80A and 80B are positioned on the sides 90d and 90e of the second housing 90, so that interference between the solenoid proportional valves 80A and 80B and other objects on the lower surface 90c of the second housing 90 can be avoided, and the add-on valve 200 can be attached to the valve unit 100. Furthermore, even with the solenoid proportional valves 80A and 80B positioned in this way, pilot chamber forming members M1 and M2 and relief valves 72 and 73 are provided on the sides 90d and 90e of the second housing 90, and the solenoid proportional valves 80A and 80B do not constitute the most protruding part, thus suppressing the size increase in the direction in which the spool 62 extends, and maintaining compactness.

[0080] The valve unit 100 may be configured as follows:

[0081] Figure 7 shows a modified example of the valve unit 100. In this example, the first primary pressure passage 41 has a primary pressure branch passage 41e (branch passage) that branches off from the primary pressure connection passage 41c instead of the primary pressure communication passage 41d, and the first drain passage 43 has a drain branch passage 43e (branch passage) that branches off from the drain connection passage 43c instead of the drain communication passage 43d.

[0082] The primary pressure branch passage 41e branches upward from the primary pressure connection passage 41c (in a direction perpendicular to the up, down, left, and right directions in Figure 1), extends to the height of the first drain passage 43 (in other words, the height of the valve body 21 of the solenoid proportional valve 20), and then extends toward the installation surface 30a of the first housing 30, opening onto the installation surface 30a and forming the outlet opening 30d. The drain branch passage 43e branches from the drain connection passage 43c toward the installation surface 30a of the first housing 30, extends toward the installation surface 30a, and opens onto the installation surface 30a, forming the outlet opening 30e. Therefore, in this example, the branch passages 41e and 43e of the first primary pressure passage 41 and the first drain passage 43, respectively, open onto the installation surface 30a of the first housing 30.

[0083] In this example, the primary pressure branch passage 41e, which branches off from the primary pressure connection passage 41c, opens onto the installation surface 30a and guides the primary pressure hydraulic fluid to the add-on valve 200. This makes it less likely for an imbalance to occur in the supply balance of hydraulic fluid between the valve unit 100 and the add-on valve 200.

[0084] In this example, the drain branch passage 43e, which branches off from the drain connection passage 43c, opens onto the installation surface 30a and guides the drained hydraulic fluid to the add-on valve 200, thus making it less likely for an imbalance to occur in the discharge balance of the hydraulic fluid between the first cap 40A and the second cap 40B.

[0085] Compared to connecting passages 41d and 43d (see Figure 1), branch passages 41e and 43e can reduce the curvature of the passages, making it easier to form passages and contributing to a reduction in manufacturing costs.

[0086] As an alternative modification, the pump P (see Figure 3) may be connected to the second cap 40B or to the first housing 30. By connecting the pump P to the primary pressure connection passage 41c of the first housing 30 without going through the caps 40A and 40B, it is possible to make it less likely for an imbalance to occur in the supply balance of hydraulic fluid between the first cap 40A and the second cap 40B.

[0087] The primary pressure communication passage 41d and the drain communication passage 43d may communicate with the main primary pressure passage 41a and the main drain passage 43a of the second cap 40B, and may be provided across the second cap 40B and the first housing 30. In addition, the primary pressure connection passage 41c and the drain connection passage 43c may be provided on the installation surface 30a side or in the center of the first housing 30 in the direction in which the solenoid proportional valves 20 are lined up.

[0088] The configuration, operation, and effects of the embodiments of the present invention will be described below.

[0089] The valve unit 100 includes a control valve 10 driven by hydraulic fluid supplied to a pilot chamber 11, an electromagnetic proportional valve 20 that controls the pressure of the hydraulic fluid supplied to the pilot chamber 11, a monoblock structure first housing 30 in which multiple control valves 10 are provided, a cap 40 attached to the first housing 30 and in which the pilot chamber 11 and the electromagnetic proportional valve 20 are provided, a first primary pressure passage 41 that supplies hydraulic fluid at primary pressure to the electromagnetic proportional valve 20, and a pilot valve that supplies hydraulic fluid supplied from the first primary pressure passage 41 and reduced to secondary pressure by the electromagnetic proportional valve 20. The first housing 30 includes a first secondary pressure passage 42 leading to a chamber 11 and a first drain passage 43 leading to the hydraulic fluid discharged from the first secondary pressure passage 42 through a solenoid proportional valve 20. The first housing 30 has an installation surface 30a to which an add-on valve 200, which is an additional control valve device equipped with an additional control valve 60 driven by the hydraulic fluid led to a pilot chamber 61 and a solenoid proportional valve 80 that controls the pressure of the hydraulic fluid led to the pilot chamber 61, can be attached. The first primary pressure passage 41 and the first drain passage 43 open to the installation surface 30a of the first housing 30.

[0090] With this configuration, the first primary pressure passage 41 opens to the installation surface 30a of the first housing 30, so the pump P can be shared between the add-on valve 200 and the valve unit 100, which are equipped with an electromagnetic proportional valve 80 and do not require a hydraulic pilot valve, and the connecting piping between the add-on valve 200 and the pump P is also unnecessary. Furthermore, since the first drain passage 43 also opens to the installation surface 30a of the first housing 30, the drain piping can also be shared between the add-on valve 200 and the valve unit 100.

[0091] The add-on valve 200 has a second housing 90 which is attached to the first housing 30 and is provided with an additional control valve 60 and an electromagnetic proportional valve 80 for the add-on valve 200, and the valve unit 100 further comprises a cover 5 which is attached to the second housing 90 of the add-on valve 200, and the pilot chamber 61 of the additional control valve 60 has a first pilot chamber 61A and a second pilot chamber 61B which are provided on each side of the additional control valve 60, and the add-on valve The solenoid proportional valve 80 of the 200 has a first solenoid proportional valve 80A and a second solenoid proportional valve 80B that control the pressure of the hydraulic fluid led to the first pilot chamber 61A and the second pilot chamber 61B, respectively, and the second housing 90 has two second primary pressure passages 94A, 94B that lead the primary pressure hydraulic fluid to the first solenoid proportional valve 80A and the second solenoid proportional valve 80B, respectively, and from the two second primary pressure passages 94A, 94B the first solenoid proportional valve 80A and the second solenoid proportional valve 80B The system includes two second secondary pressure passages 95A and 95B that guide the hydraulic fluid, which has been reduced to a secondary pressure, to the first pilot chamber 61A and the second pilot chamber 61B, and two second drain passages 96A and 96B that guide the hydraulic fluid discharged from each of the two second secondary pressure passages 95A and 95B through the first solenoid proportional valve 80A and the second solenoid proportional valve 80B, and a primary pressure passage that, when attached to the first housing 30, communicates with the outlet opening 30d of the first primary pressure passage 41 formed on the installation surface 30a. The cover 5 has a through hole 97 and a drain through hole 98 that communicates with the outlet opening 30e of the first drain passage 43 formed in the installation surface 30a when attached to the first housing 30. The cover 5 has a primary pressure connecting passage 6 that connects the primary pressure through hole 97 to two second primary pressure passages 94 when attached to the second housing 90, and a drain connecting passage 7 that connects the drain through hole 98 to two second drain passages 96 when attached to the second housing 90.

[0092] With this configuration, it is not necessary to provide a second primary pressure passage 94 and a second drain passage 96 in the second housing 90 to connect the first solenoid proportional valve 80A and the second solenoid proportional valve 80B. As a result, the second housing 90 can be made smaller by the amount of the portion R that does not require the formation of these passages 94 and 96. Therefore, by improving the overall layoutability of the valve unit 100 and the add-on valve 200 through the miniaturization of the second housing 90, the layoutability of the valve unit 100 can be improved.

[0093] The cap 40 has a first cap 40A provided on one installation surface 30ba as a first side surface of the first housing 30, and a second cap 40B provided on the other installation surface 30bb as a second side surface of the first housing 30 opposite to the one installation surface 30ba, and the first primary pressure passage 41 and the first drain passage 43 each have a main primary pressure passage 41a and a main drain passage 43a as first passages formed in the first cap 40A, and a main primary pressure passage 41a and a main drain passage 43a as second passages formed in the second cap 40B, and the first The woving 30 is formed and includes a main primary pressure passage 41a and a main drain passage 43a as a first passage, a primary pressure connection passage 41c and a drain connection passage 43c as a third passage that connects the main primary pressure passage 41a and the main drain passage 43a as a second passage, and primary pressure branch passages 41e and a drain branch passage 43e that branch off from the primary pressure connection passage 41c and the drain connection passage 43c as the third passage, with the primary pressure branch passages 41e and 43e of the first primary pressure passage 41 and the first drain passage 43 opening at the installation surface 30a of the first housing 30.

[0094] This configuration makes it less likely for the supply balance of hydraulic fluid to be uneven between the valve unit 100 and the add-on valve 200, and also makes it less likely for the discharge balance of hydraulic fluid to be uneven between the first cap 40A and the second cap 40B.

[0095] 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]

[0096] 5...Cover, 6...Primary pressure connection passage, 7...Drain connection passage, 10, 10A...Control valve, 11...Pilot chamber, 20...Solenoid proportional valve, 30...First housing, 30a...Mounting surface, 30ba...Mounting surface (first side), 30bb...Mounting surface (second side), 30d...Outlet opening (opening), 30e...Outlet opening (opening), 40...Cap, 40A...First cap, 40B...Second cap, 41...First primary pressure passage, 41a...Main primary pressure passage (first passage, second passage), 41c...Primary pressure connection passage (third passage), 41e...Primary pressure branch passage (branch passage), 42...First secondary pressure passage, 43... 1st drain passage, 43a... Main drain passage (1st passage, 2nd passage), 43c... Drain connection passage (3rd passage), 43e... Drain branch passage (branch passage), 60... Additional control valve, 61... Pilot chamber, 61A... 1st pilot chamber, 61B... 2nd pilot chamber, 80... Solenoid proportional valve, 80A... 1st solenoid proportional valve, 80B... 2nd solenoid proportional valve, 90... 2nd housing, 94, 94A, 94B... 2nd primary pressure passage, 95, 95A, 95B... 2nd secondary pressure passage, 96, 96A, 96B... 2nd drain passage, 97... Primary pressure through hole, 98... Drain through hole, 200... Add-on valve (additional control valve device)

Claims

1. A control valve driven by a working fluid supplied to the pilot chamber, An electromagnetic proportional valve that controls the pressure of the working fluid supplied to the pilot chamber, A first housing with a monoblock structure in which a plurality of the control valves are provided, A cap attached to the first housing, on which the pilot chamber and the electromagnetic proportional valve are provided, A first primary pressure passage that guides the working fluid at primary pressure to the solenoid proportional valve, A first secondary pressure passage leads the working fluid, which is guided from the first primary pressure passage and reduced to a secondary pressure by the electromagnetic proportional valve, to the pilot chamber, It comprises a first drain passage that guides the working fluid discharged from the first secondary pressure passage through the electromagnetic proportional valve, The first housing has an mounting surface to which an additional control valve device can be attached, which is provided with an additional control valve driven by a working fluid introduced into a pilot chamber and an electromagnetic proportional valve that controls the pressure of the working fluid introduced into the pilot chamber. The first primary pressure passage and the first drain passage open to the mounting surface of the first housing. A valve unit characterized by the following features.

2. A valve unit according to claim 1, The additional control valve device has a second housing in which the additional control valve and the electromagnetic proportional valve of the additional control valve device are provided and attached to the first housing, The additional control valve device further comprises a cover that is attached to the second housing, The pilot chamber of the additional control valve has a first pilot chamber and a second pilot chamber, which are provided on each side of the additional control valve. The solenoid proportional valve of the additional control valve device has a first solenoid proportional valve and a second solenoid proportional valve that control the pressure of the working fluid supplied to the first pilot chamber and the second pilot chamber, respectively. The preceding 2 housing is, Two second primary pressure passages for guiding the primary pressure working fluid to the first and second solenoid proportional valves, Two second secondary pressure passages that guide the working fluid, which is led from each of the two second primary pressure passages and reduced to a secondary pressure by the first and second electromagnetic proportional valves, to the first and second pilot chambers, Two second drain passages for guiding the working fluid discharged from each of the two second secondary pressure passages through the first and second electromagnetic proportional valves, With the first housing attached, a primary pressure through-hole is provided that communicates with the opening of the first primary pressure passage formed on the mounting surface, When attached to the first housing, it has a drain through-hole that communicates with the opening of the first drain passage formed on the installation surface, The aforementioned cover is With the second housing attached, a primary pressure connecting passage connects the primary pressure through hole and the two second primary pressure passages, When attached to the second housing, it has a drain connection passage that connects the drain through hole and the two second drain passages, A valve unit characterized by the following features.

3. A valve unit according to claim 1, The cap comprises a first cap provided on a first side surface of the first housing and a second cap provided on a second side surface of the first housing opposite to the first side surface. Each of the first primary pressure passage and the first drain passage includes a first passage formed in the first cap, a second passage formed in the second cap, a third passage formed in the first housing that connects the first passage and the second passage, and a branch passage that branches off from the third passage. The installation surface of the first housing has openings for the branch passages of the first primary pressure passage and the first drain passage. A valve unit characterized by the following features.

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