Fluid pressure control device

Abstract

To prevent the fluid pressure control device from increasing in size when a neutral cut valve is newly added.SOLUTION: A fluid pressure control device 100 comprises: a first circuit system 10; a second circuit system 20; and a valve block 3 having a first region R1 in which first control valves 121 to 125 are accommodated, and a second region R2 in which second control valves 221 to 224 are accommodated. The first circuit system 10 has a first neutral cut valve 40 that makes or breaks the connection between a first neutral passage 11 and a tank T, and the second circuit system 20 has a second neutral cut valve 60 that makes or breaks the connection between a second neutral passage 21 and the tank T. The first neutral cut valve 40 and the second neutral cut valve 60 are accommodated in either one of the first region R1 and the second region R2.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a fluid pressure control device.

Background Art

[0002] Patent Document 1 discloses a fluid pressure control device including a first circuit system connected to a first pump and supplied with hydraulic oil discharged from the first pump, and a second circuit system connected to a second pump and supplied with hydraulic oil discharged from the second pump. The second circuit system of the fluid pressure control device described in Patent Document 1 has a second neutral passage that guides the hydraulic oil supplied from the second pump to the tank, a plurality of actuator control valves connected in series to the second neutral passage, and a neutral cut valve connected to the second neutral passage on the downstream side of the actuator control valve.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the fluid pressure control device described in Patent Document 1, it is conceivable to provide a neutral cut valve in the first circuit system as well to communicate or cut off the first neutral passage and the discharge passage. In that case, if a neutral cut valve is provided in the valve block that houses the first circuit system, the valve block will become larger by the space for accommodating the neutral cut valve.

[0005] The present invention has been made in view of the above problems, and an object thereof is to suppress the enlargement of the fluid pressure control device when newly adding a neutral cut valve.

Means for Solving the Problems

[0006] The present invention relates to a fluid pressure control device comprising: a first circuit system having at least one first control valve connected to a first pump and controlling an actuator; a second circuit system having at least one second control valve connected to a second pump and controlling an actuator; and a valve block having a first region housing the first control valve and a second region housing the second control valve, wherein the first circuit system includes a first neutral passage that returns the working fluid of the first pump to a tank when all first control valves are in the neutral position, and The second circuit system includes a first neutral cut valve provided downstream of a first control valve, which connects or disconnects the first neutral passage and the tank, and a second neutral cut valve provided downstream of the second control valve in the second neutral passage, which connects or disconnects the second neutral passage and the tank, and the first neutral cut valve and the second neutral cut valve are housed in either the first region or the second region.

[0007] In this invention, the first neutral cut-off valve and the second neutral cut-off valve are housed in either the first or second region. For example, when adding a new first neutral cut-off valve, the first neutral cut-off valve can be housed in the region where the second neutral cut-off valve is already installed. Therefore, it is not necessary to secure new space to house the additional first neutral cut-off valve. Thus, the size of the fluid pressure control device can be suppressed.

[0008] Furthermore, the present invention is characterized in that the first neutral cut-off valve has a first spool that shuts off or opens the connection between the first neutral passage and the tank, the second neutral cut-off valve has a second spool that shuts off or opens the connection between the second neutral passage and the tank, and the first spool and the second spool are arranged coaxially.

[0009] In this invention, since the first spool of the first neutral cut-off valve and the second spool of the second neutral cut-off valve are arranged coaxially, the size of the fluid pressure control device can be suppressed compared to the case where the first spool of the first neutral cut-off valve and the second spool of the second neutral cut-off valve are arranged offset from each other.

[0010] Furthermore, the present invention is characterized in that the first spool and the second spool are housed in the same through-hole formed in the valve block.

[0011] In this invention, the first spool of the first neutral cut valve and the second spool of the second neutral cut valve are housed in the same through-hole formed in the valve block. This reduces the number of processing steps compared to the case where the first spool and the second spool of the second neutral cut valve are provided in separate housing holes.

[0012] Furthermore, in the present invention, the first circuit system is provided downstream of the first neutral cut-off valve in the first neutral passage and further comprises a first relief valve that defines the maximum pressure in the first neutral passage, and the second circuit system is provided downstream of the second neutral cut-off valve in the second neutral passage and further comprises a second relief valve that defines the maximum pressure in the second neutral passage, and the first neutral cut-off valve, the second neutral cut-off valve, the first relief valve and the second relief valve are provided in the same region, either the first region or the second region.

[0013] In this invention, by effectively utilizing the dead space that was present in the first or second region, it is possible to suppress the increase in size of the valve block. [Effects of the Invention]

[0014] According to the present invention, when a neutral cut-off valve is added, it is not necessary to secure additional space to accommodate the added neutral cut-off valve, thus preventing an increase in the size of the fluid pressure control device. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 is a circuit diagram showing a fluid pressure control device according to an embodiment of the present invention. [Figure 2] Figure 2 is a structural cross-sectional view of the vicinity of the first neutral cut-off valve and the second neutral cut-off valve according to an embodiment of the present invention. [Figure 3]Figure 3 is a diagram illustrating the concepts of the first and second regions in a fluid pressure control device according to an embodiment of the present invention. [Modes for carrying out the invention]

[0016] Hereinafter, a fluid pressure control device 100 according to an embodiment of the present invention will be described with reference to the drawings.

[0017] The fluid pressure control device 100 is used in work machines such as power shovels. While this explanation focuses on the case where the work machine is a power shovel, the fluid pressure control device 100 is also applicable to other work machines such as wheel loaders. Furthermore, while hydraulic oil is used as the working fluid in the fluid pressure control device 100, other fluids such as hydraulic water may also be used as the working fluid.

[0018] As shown in Figure 1, the fluid pressure control device 100 includes a first circuit system 10 connected to a first pump P1 and supplied with hydraulic fluid from the first pump P1, and a second circuit system 20 connected to a second pump P2 and supplied with hydraulic fluid from the second pump P2.

[0019] The first circuit system 10 includes a first neutral passage 11 that guides the hydraulic fluid supplied from the first pump P1 to the tank T, first control valves 121 to 125 connected in series to the first neutral passage 11, and a first parallel passage 13 that branches off from the first neutral passage 11 upstream of the first control valves 121 to 125. The first control valves 121 to 125 are connected in series by the first neutral passage 11 and in parallel by the first parallel passage 13.

[0020] The hydraulic oil discharged from the first pump P1 is guided to the first travel control valve 121, the standby control valve 122, the swing control valve 123, the boom two-speed control valve 124, and the arm one-speed control valve 125 in order from the upstream side. The first travel control valve 121 controls the supply and discharge of hydraulic oil to the travel motor provided on the left side of the body of a hydraulic excavator (not shown). The standby control valve 122 controls the supply and discharge of hydraulic oil to the actuator that drives attachments such as a breaker or a crusher attached in place of the bucket. The swing control valve 123 controls the supply and discharge of hydraulic oil to the swing motor that swings the swing body disposed on the upper part of the body. The boom two-speed control valve 124 controls the supply and discharge of hydraulic oil to the actuator that drives the boom. The arm one-speed control valve 125 controls the supply and discharge of hydraulic oil to the actuator (arm cylinder 90) that drives the arm.

[0021] In the first circuit system 10, when all of the first control valves 121 to 125 are in the neutral position, the hydraulic oil supplied from the first pump P1 is returned to the tank T through the first neutral passage 11. On the other hand, when at least one of the first control valves 121 to 125 is in the operating position, the connection between the first pump P1 and the tank T in the first neutral passage 11 is blocked.

[0022] Also, in the first circuit system 10, even when any one of the first control valves 121 to 124 is switched to the operating position and the connection between the first pump P1 and the tank T in the first neutral passage 11 is blocked, the hydraulic oil supplied from the first pump P1 can be supplied to each of the first control valves 122 to 125 through the first parallel passage 13.

[0023] The first circuit system 10 is provided downstream of the first control valves 121 to 125 in the first neutral passage 11, and further includes a first neutral cut-off valve 40 that communicates or blocks the connection between the first neutral passage 11 and the tank T, and a first relief valve 81 that is provided downstream of the first neutral cut-off valve 40 in the first neutral passage 11 and defines the maximum pressure of the first neutral passage 11. When the first neutral cut-off valve 40 is in the G position (normal position) in FIG. 1, the connection between the first neutral passage 11 and the tank T is communicated, and when in the H position (cut-off position), the connection between the first neutral passage 11 and the tank T is blocked.

[0024] Next, the operation of the first neutral cut-off valve 40 will be specifically described.

[0025] The first neutral cut-off valve 40 is located at the G position (normal position) in FIG. 1 when no pilot pressure is supplied. In this state, the hydraulic oil flowing into the first neutral cut-off valve 40 from downstream of the first gear speed control valve 125 in the first neutral passage 11 is refluxed to the tank T. That is, when the first neutral cut-off valve 40 is in the G position (normal position), the first neutral passage 11 and the tank T are communicated.

[0026] When pilot pressure is supplied to the first neutral cut-off valve 40 from this state, it switches to the H position (cut-off position) in FIG. 1. In this state, the hydraulic oil flowing into the first neutral cut-off valve 40 from downstream of the first gear speed control valve 125 in the first neutral passage 11 is prevented from flowing out to the tank T. That is, by switching the first neutral cut-off valve 40 to the H position (cut-off position), the connection between the first neutral passage 11 and the tank T is blocked. As a result, the hydraulic oil flowing through the first neutral passage 11 is guided to the first external output port 19 branched from between the first gear speed control valve 125 and the first neutral cut-off valve 40 in the first neutral passage 11. The hydraulic oil guided to the first external output port 19 is used for driving hydraulic equipment and the like.

[0027] Next, the first gear speed control valve 125 will be described with reference to FIG. 1.

[0028] As shown in Figure 1, the control valve 125 for the first speed of the arm is connected to a first neutral passage 11, a supply passage 12 that branches off from the first neutral passage 11 and supplies hydraulic fluid for driving the arm cylinder 90, a first cylinder passage 91a that communicates with the high-load pressure chamber 90a of the arm cylinder 90, a second cylinder passage 91b that communicates with the low-load pressure chamber 90b of the arm cylinder 90, a first tank passage 14 that discharges the hydraulic fluid from the pressure chamber 90a to the tank T, and a second tank passage 15 that discharges the hydraulic fluid from the pressure chamber 90b to the tank T.

[0029] The supply passage 12 is joined by the first parallel passage 13 (first parallel downstream passage 13b). Upstream of the confluence P of the supply passage 12 and the first parallel passage 13 (first parallel downstream passage 13b) in the supply passage 12, a check valve 17 is provided to prevent backflow of hydraulic fluid. Furthermore, upstream of the confluence P of the supply passage 12 and the first parallel passage 13 (first parallel downstream passage 13b) in the first parallel passage 13, from upstream to downstream, a check valve 76 is provided to prevent backflow of hydraulic fluid, and a flow control valve 70 is provided to control the flow rate of hydraulic fluid passing through the first parallel passage 13.

[0030] The first tank passage 14 is equipped with a regeneration release valve 50 that controls the flow rate of hydraulic fluid passing through the first tank passage 14 according to the pilot pressure. The function of the regeneration release valve 50 will be explained later.

[0031] The control valve 125 for the first speed arm can be switched between three positions: a neutral position A shown in Figure 1, a high-load operating position B shown on the right side of Figure 1, and a low-load operating position C shown on the left side of Figure 1. Positions A, B, and C of the control valve 125 for the first speed arm are switched according to the pilot pressure supplied to the pilot chambers 125a and 125b located at both ends of the control valve 125 for the first speed arm. When no pilot pressure is acting on either pilot chamber 125a or 125b, the control valve 125 for the first speed arm is in the neutral position A due to the biasing force of the springs 125c located on both sides of the control valve 125 for the first speed arm. When pilot pressure is supplied to pilot chamber 125b, the control valve 125 for the first speed arm switches to the high-load operating position B, and when pilot pressure is supplied to pilot chamber 125a, the control valve 125 for the first speed arm switches to the low-load operating position C.

[0032] In neutral position A, the first neutral passage 11 is connected to the tank T, and the other passages are blocked. As a result, no hydraulic fluid is supplied to or discharged from the pressure chambers 90a and 90b of the arm cylinder 90, and the arm cylinder 90 is held in that position.

[0033] In the high-load operating position B, the first neutral passage 11 is closed, the supply passage 12 is connected to the first cylinder passage 91a, and the second cylinder passage 91b is connected to the second tank passage 15. As a result, the hydraulic fluid discharged from the first pump P1 is supplied to the pressure chamber 90a from the first neutral passage 11 and the first parallel passage 13 (first parallel downstream passage 13b) through the supply passage 12 and the first cylinder passage 91a. The hydraulic fluid in the pressure chamber 90b is then discharged to the tank T through the second cylinder passage 91b and the second tank passage 15.

[0034] In the low-load operating position C, the first neutral passage 11 is closed, the supply passage 12 is connected to the second cylinder passage 91b, and the first cylinder passage 91a is connected to the first tank passage 14. As a result, the hydraulic fluid discharged from the first pump P1 is supplied to the pressure chamber 90b through the supply passage 12 and the second cylinder passage 91b from the first neutral passage 11 and the first parallel passage 13. The hydraulic fluid in the pressure chamber 90a is discharged to the tank T through the first cylinder passage 91a and the first tank passage 14. At this time, the regeneration release valve 50 controls the flow rate of the hydraulic fluid discharged to the tank T through the first tank passage 14.

[0035] Furthermore, within the control valve 125 for the first speed of the arm, a first internal passage 126 is formed that connects the first cylinder passage 91a and the first tank passage 14 at the low-load operating position C, a second internal passage 127 is formed that connects the supply passage 12 and the second cylinder passage 91b, and a regeneration passage 128 is formed that connects the first internal passage 126 and the second internal passage 127. The regeneration passage 128 is provided with a check valve 129 that allows flow only from the first internal passage 126 to the second internal passage 127. Therefore, the hydraulic fluid discharged from the pressure chamber 90a can be regenerated into the pressure chamber 90b through the regeneration passage 128. The first internal passage 126 is provided with a throttle that restricts the flow rate of the hydraulic fluid discharged from the pressure chamber 90a.

[0036] Next, the operation of the regeneration release valve 50 will be explained.

[0037] The regeneration release valve 50 adjusts the flow rate of hydraulic fluid returned from the high-load side pressure chamber 90a to the tank T through the first tank passage 14 when the control valve 125 for the first speed of the arm is switched to the low-load side operating position C. Specifically, when pilot pressure is supplied to the pilot chamber 125a of the control valve 125 for the first speed of the arm, the control valve 125 for the first speed of the arm is switched to the low-load side operating position C. As a result, the hydraulic fluid in the high-load side pressure chamber 90a of the arm cylinder 90 flows out to the tank T through the first cylinder passage 91a, the first internal passage 126, the first tank passage 14, and the regeneration release valve 50.

[0038] When the pilot pressure acting on the pilot pressure chamber of the regeneration release valve 50 through the supply passage 12 and pilot passage 16 is low, the valve body of the regeneration release valve 50 blocks a portion of the flow path, thereby restricting the flow path. In this state, the flow rate of hydraulic fluid that can pass through the regeneration release valve 50 is small. Therefore, most of the hydraulic fluid discharged from the pressure chamber 90a is regenerated into the pressure chamber 90b through the regeneration passage 128.

[0039] As the pilot pressure acting on the internal pilot pressure chamber 55 increases from this state, the valve body moves against the biasing force of the return spring, thereby expanding the area of ​​the flow path. Consequently, the flow rate of hydraulic fluid that can pass through the regeneration release valve 50 increases, and the flow rate of hydraulic fluid regenerated from pressure chamber 90a to pressure chamber 90b through the regeneration passage decreases. As the pilot pressure acting on the pilot pressure chamber of the regeneration release valve 50 increases further, the valve body moves even further against the biasing force of the return spring. As a result, the flow rate of hydraulic fluid that can pass through the first tank passage 14 increases even further. Consequently, hydraulic fluid is not regenerated from pressure chamber 90a to pressure chamber 90b through the regeneration passage 128, and the entire amount of hydraulic fluid in pressure chamber 90a is discharged to tank T.

[0040] In this way, the regeneration release valve 50 adjusts the flow rate of hydraulic fluid passing through the first tank passage 14 in accordance with the pilot pressure acting on the pilot pressure chamber, thereby adjusting the flow rate of fluid regenerated from the pressure chamber 90a to the pressure chamber 90b through the regeneration passage 128.

[0041] In the fluid pressure control device 100 equipped with an internal pilot-type regeneration release valve 50, if the pressure of the hydraulic fluid in the supply passage 12 decreases due to the combined operation of the cylinder, that is, if the pilot pressure decreases, the regeneration release valve 50 can regenerate the hydraulic fluid in the pressure chamber 90a into the pressure chamber 90b by throttling the first tank passage 14. Conversely, if the pressure of the hydraulic fluid in the supply passage 12 is high (does not decrease), that is, if the pilot pressure is high, such as when the arm cylinder 90 is operated alone, the regeneration release valve 50 opens the first tank passage 14, thereby discharging the hydraulic fluid in the pressure chamber 90a into the tank T without regenerating it into the pressure chamber 90b. In this embodiment, the case where the regeneration release valve 50 is an internal pilot type has been described as an example, but the regeneration release valve 50 may also be an external pilot type.

[0042] Next, the operation of the flow control valve 70 will be explained.

[0043] The flow control valve 70 is located on the first parallel passage 13 (first parallel downstream passage 13b). The flow control valve 70 adjusts the flow rate of hydraulic fluid flowing through the first parallel downstream passage 13b in accordance with the pressure of the hydraulic fluid supplied to the pilot pressure chamber from the outside through the pilot passage 18 (pilot pressure). Specifically, as the pressure of the hydraulic fluid supplied to the pilot pressure chamber increases, the flow control valve 70 reduces the flow rate of hydraulic fluid passing through the flow control valve 70 (flow rate in the first parallel downstream passage 13b). The hydraulic fluid flowing through the first parallel downstream passage 13b is supplied to the arm cylinder 90 through the supply passage 12 and the arm 1 speed control valve 125. Therefore, by controlling the flow rate of hydraulic fluid passing through the flow control valve 70, the flow rate of hydraulic fluid supplied to the arm cylinder 90 can be controlled. This allows, for example, when multiple actuators including the arm cylinder 90 are operated in combination, the flow rate of hydraulic fluid supplied to the arm cylinder 90 to be limited, thereby supplying that amount of hydraulic fluid to other actuators. As a result, when multiple actuators are operated in combination, it is possible to avoid a situation where only the arm cylinder 90 is driven first.

[0044] Next, we will explain the second circuit system 20 with reference to Figure 1.

[0045] The second circuit system 20 includes a second neutral passage 21 that guides the hydraulic fluid supplied from the second pump P2 to the tank T, a plurality of second control valves 221 to 224 connected in series to the second neutral passage 21, and a second parallel passage 23 that branches off from the second neutral passage 21 upstream of the second control valves 221 to 224. The second control valves 221 to 224 are connected in series by the second neutral passage 21 and in parallel by the second parallel passage 23.

[0046] The hydraulic fluid discharged from the second pump P2 is directed, in order from upstream, to the second travel control valve 221, the bucket control valve 222, the boom 1st speed control valve 223, and the arm 2nd speed control valve 224. The second travel control valve 221 controls the supply and discharge of hydraulic fluid to the travel motor located on the right side of the body of the power shovel (not shown). The bucket control valve 222 controls the supply and discharge of hydraulic fluid to the actuator that drives the bucket. The boom 1st speed control valve 223 controls the supply and discharge of hydraulic fluid to the actuator that drives the boom. The arm 2nd speed control valve 224 controls the supply and discharge of hydraulic fluid to the actuator that drives the arm.

[0047] In the second circuit system 20, when all second control valves 221 to 224 are in the neutral position, the hydraulic fluid supplied from the second pump P2 is returned to the tank T through the second neutral passage 21. Conversely, when at least one of the second control valves 221 to 224 is in the activated position, the connection between the second pump P2 and the tank T in the second neutral passage 21 is disconnected.

[0048] Furthermore, in the second circuit system 20, even if any of the second control valves 221 to 223 are switched to the operating position and the connection between the second pump P2 and the tank T in the second neutral passage 21 is interrupted, the hydraulic fluid supplied from the second pump P2 can still be supplied to each of the second control valves 222 to 224 through the second parallel passage 23.

[0049] The second circuit system 20 further includes a second neutral cut-off valve 60 located downstream of the arm 2 speed control valve 224 in the second neutral passage 21, which connects or disconnects the second neutral passage 21 and the tank T, and a second relief valve 82 located downstream of the second neutral cut-off valve 60 in the second neutral passage 21, which defines the maximum pressure in the second neutral passage 21. The second neutral cut-off valve 60 and the second relief valve 82 are the same configuration as the first neutral cut-off valve 40 and the first relief valve 81, respectively.

[0050] The second circuit system 20 is located downstream of the arm 2 speed control valve 224 in the second neutral passage 21 and communicates upstream of the second neutral cut-off valve 60, and further includes a second external output port 29 capable of supplying hydraulic fluid discharged from the second pump P2 to the outside. The function of the second neutral cut-off valve 60 is the same as that of the first neutral cut-off valve 40, so its description is omitted.

[0051] The second circuit system 20 further includes a straight-ahead travel control valve 25 connected downstream of the branching point with the second parallel passage 23 in the second neutral passage 21 and upstream of the second travel control valve 221. The first parallel passage 13 is connected to the straight-ahead travel control valve 25. The first parallel passage 13 has a first parallel upstream passage 13a connecting the first pump P1 and the straight-ahead travel control valve 25, and a first parallel downstream passage 13b connecting the straight-ahead travel control valve 25 and the first control valves 122 to 125.

[0052] The straight-ahead driving control valve 25 can be switched between two positions: the normal position D shown on the right side of Figure 1, and the straight-ahead driving position E shown on the left side of Figure 1. Positions D and E of the straight-ahead driving control valve 25 are switched according to the pilot pressure supplied to the pilot chambers 25a located at both ends of the straight-ahead driving control valve 25. When no pilot pressure is acting on the pilot chambers 25a, the straight-ahead driving control valve 25 is in the normal position D due to the biasing force of the spring 25b. When pilot pressure is supplied to the pilot chambers 25a, the straight-ahead driving control valve 25 switches to the straight-ahead driving position E.

[0053] In the normal position D, the first parallel upstream passage 13a of the first parallel passage 13 is connected to the first parallel downstream passage 13b of the first parallel passage 13, and the second neutral passage 21 is connected to the second pump P2. As a result, the hydraulic fluid discharged from the first pump P1 is supplied to the first control valves 121 to 125 through the first neutral passage 11 and the first parallel passage 13. Also, the hydraulic fluid discharged from the second pump P2 is supplied to the second control valves 221 to 224 through the second neutral passage 21 and the second parallel passage 23. In other words, when only the travel motor is operated, the first travel control valve 121 is supplied with hydraulic fluid discharged from the first pump P1, and the second travel control valve 221 is supplied with hydraulic fluid discharged from the second pump P2.

[0054] In the straight-ahead driving position E, the first parallel upstream passage 13a of the first parallel passage 13 is connected to the second neutral passage 21 downstream of the straight-ahead driving control valve 25, and the first parallel downstream passage 13b is connected to the second pump P2. In other words, when the driving motor and actuators other than the driving motor are operated simultaneously, the first driving control valve 121 and the second driving control valve 221 are supplied with hydraulic fluid discharged from the first pump P1, and the other first control valves 122 to 125 and the other second control valves 222 to 224 are supplied with hydraulic fluid discharged from the second pump P2. Therefore, in the straight-ahead driving position E, even when the driving motor and actuators other than the driving motor are operated simultaneously, the circuit for the driving motor and the circuit for actuators other than the driving motor remain independent, thus ensuring the straight-ahead driving stability of the vehicle body.

[0055] As shown in Figure 1, in the fluid pressure control device 100, each valve of the first circuit system 10 and the second circuit system 20 is housed within a single valve block 3. Specifically, as shown in Figure 3, the valve block 3 has a first region R1 in which the first control valves 121 to 125 of the first circuit system 10 are housed, and a second region R2 in which the second control valves 221 to 224 and the straight-ahead driving control valve 25 of the second circuit system 20 are housed. In this embodiment, the first region R1 and the second region R2 are provided so as to divide the valve block 3 vertically in the longitudinal direction.

[0056] As shown in Figure 3, the first control valves 121 to 125 of the first circuit system 10 are arranged in the longitudinal direction of the valve block 3 within the first region R1. The second control valves 221 to 224 of the second circuit system 20 are arranged in the longitudinal direction of the valve block 3 within the second region R2.

[0057] Next, the specific structures of the first neutral cut-off valve 40 and the second neutral cut-off valve 60 will be described with reference to Figure 2. Figure 2 is a cross-sectional view showing the first neutral cut-off valve 40 and the second neutral cut-off valve 60 in their normal positions. Note that the configurations of the regeneration release valve 50, flow control valve 70, check valve 76, and the first and second relief valves 81 and 82 are common and will therefore not be explained.

[0058] As shown in Figure 2, the valve block 3 is provided with a first housing hole 31 that accommodates a spool 41 as the first spool of the first neutral cut-off valve 40 and a spool 61 as the second spool of the second neutral cut-off valve 60. The first housing hole 31 is formed as a cylindrical through hole that opens to both sides of the valve block 3.

[0059] The first neutral cut-off valve 40 includes a spool 41 housed in a first housing hole 31 that blocks or opens the connection between the first neutral passage 11 and the tank T, a pilot pressure chamber 43 provided on one end of the spool 41 and formed by a valve block 3 and a cap member 42, and a return spring 44 provided in the pilot pressure chamber 43 that biases the spool 41 in the direction that connects the first neutral passage 11 and the tank T (to the right in Figure 2). The cap member 42 is provided with a pilot port 45 for supplying and discharging pilot pressure to and from the pilot pressure chamber 43.

[0060] The spool 41 includes a first land portion 41a and a second land portion 41b that slide along the inner circumferential surface of the first housing hole 31, and an annular groove 41c formed between the first land portion 41a and the second land portion 41b. The first neutral passage 11 is opened and closed as the first land portion 41a moves within the first housing hole 31.

[0061] The second neutral cut-off valve 60 includes a spool 61 housed in the first housing hole 31 that blocks or opens the connection between the second neutral passage 21 and the tank T, a pilot pressure chamber 63 provided on one end of the spool 61 and formed by a valve block 3 and a cap member 62, and a return spring 64 provided in the pilot pressure chamber 63 that biases the spool 61 in the direction that connects the second neutral passage 21 and the tank T (to the left in Figure 2). The cap member 62 is provided with a pilot port 65 for supplying and discharging pilot pressure to and from the pilot pressure chamber 63.

[0062] The spool 61 includes a first land portion 61a and a second land portion 61b that slide along the inner circumferential surface of the first housing hole 31, and an annular groove 61c formed between the first land portion 61a and the second land portion 61b. The second neutral passage 21 is opened and closed as the first land portion 61a moves within the first housing hole 31.

[0063] A drain chamber 32, which communicates with the tank T, is formed between the other end of the spool 41 and the spool 61 in the first housing hole 31.

[0064] In the fluid pressure control device 100 of this embodiment, the first neutral cut-off valve 40 is located in the second region R2. In addition, in the fluid pressure control device 100 of this embodiment, the first circuit system 10 is equipped with a regeneration release valve 50 and a flow control valve 70, which are located in the first region R1. For example, if the first neutral cut-off valve 40 were to be located in the first region R1, it would be necessary to secure new space above the cross-section shown in Figure 2, or to extend the valve block 3 in the longitudinal direction to secure new space. The second circuit system 20 does not have valves such as the regeneration release valve 50 and the flow control valve 70, so there is ample space in the second region R2. Therefore, in the fluid pressure control device 100 of this embodiment, the first neutral cut-off valve 40 is located in the second region R2. This eliminates the need to secure new space to accommodate the first neutral cut-off valve 40. Thus, even with the provision of the first neutral cut-off valve 40, the size of the fluid pressure control device 100 can be kept from increasing.

[0065] Furthermore, in the fluid pressure control device 100, the spool 41 of the first neutral cut valve 40 and the spool 61 of the second neutral cut valve 60 are housed in the same first housing hole 31. This reduces the number of processing steps compared to the case where the spool 41 and the spool 61 are provided in separate housing holes. Moreover, in the fluid pressure control device 100, because the spool 41 of the first neutral cut valve 40 and the spool 61 of the second neutral cut valve 60 are housed in the same first housing hole 31, the spool 41 and the spool 61 are arranged coaxially. This suppresses the increase in size of the fluid pressure control device 100 compared to the case where the spool 41 of the first neutral cut valve 40 and the spool 61 of the second neutral cut valve 60 are arranged in a misaligned manner.

[0066] In the fluid pressure control device 100 of the above embodiment, the example described was that the spool 41 of the first neutral cut-off valve 40 and the spool 61 of the second neutral cut-off valve 60 are housed in the same first housing hole 31. However, the spool 41 of the first neutral cut-off valve 40 and the spool 61 of the second neutral cut-off valve 60 may be housed in separate housing holes. Also, if there is sufficient space in the valve block 3, the spool 41 of the first neutral cut-off valve 40 and the spool 61 of the second neutral cut-off valve 60 may be offset from each other.

[0067] Furthermore, in the fluid pressure control device 100, the first relief valve 81 of the first circuit system 10 is also provided in the second region R2. The first neutral cut-off valve 40 is provided between the first relief valve 81 and the flow control valve 70 provided in the first region R1 in the cross-section shown in Figure 2 (a cross-section perpendicular to the longitudinal direction of the valve block 3). By adopting this configuration, the dead space in the second region R2 can be effectively utilized, and the size of the valve block 3 can be suppressed.

[0068] In the above embodiment, the case in which the regeneration release valve 50 and flow control valve 70 are provided in the first circuit system 10 was described as an example, but instead, valves such as the regeneration release valve 50 and flow control valve 70 may be provided in the second circuit system 20. In this case, the first neutral cut valve 40 and the second neutral cut valve 60 should be provided in the first region R1.

[0069] Furthermore, although the above embodiment was described using the example of a case where the first circuit system 10 is equipped with a regeneration release valve 50 and a flow control valve 70, it is not limited to this and can also be applied when valves with other functions, such as a speed switching valve for switching the speed of the arm cylinder 90, are provided. Moreover, the first circuit system 10 may be configured without a regeneration release valve 50 and a flow control valve 70. Even in this case, by providing the first neutral cut valve 40 and the second neutral cut valve 60 in either the first region R1 or the second region R2, the space where the first neutral cut valve 40 and the second neutral cut valve 60 do not exist can be eliminated.

[0070] In the above embodiment, the flow control valve 70 is of the external pilot type, but it is not limited to this, and for example, it may be of the internal pilot type, where the load pressure of any actuator is used as the pilot pressure.

[0071] The configuration, operation, and effects of the embodiment of the present invention configured as described above will be summarized below.

[0072] The fluid pressure control device 100 comprises a first circuit system 10 having at least one first control valve 121-125 connected to the first pump P1 and controlling the actuator, a second circuit system 20 having at least one second control valve 221-224 connected to the second pump P2 and controlling the actuator, and a valve block 3 having a first region R1 housing the first control valves 121-125 and a second region R2 housing the second control valves 221-224, wherein the first circuit system 10 includes a first neutral passage 11 that recirculates the working fluid of the first pump P1 to the tank T when all the first control valves 121-125 are in the neutral position, and a first neutral The second circuit system 20 includes a first neutral cut valve 40 located downstream of the first control valves 121 to 125 in the passage 11, which connects or disconnects the first neutral passage 11 and the tank T, and a second neutral passage 21 which allows the working fluid of the second pump P2 to be returned to the tank T when all the second control valves 221 to 224 are in the neutral position, and a second neutral cut valve 60 located downstream of the second control valves 221 to 224 in the second neutral passage 21, which connects or disconnects the second neutral passage 21 and the tank T, with the first neutral cut valve 40 and the second neutral cut valve 60 housed in either the first region R1 or the second region R2.

[0073] In this configuration, the first neutral cut-off valve 40 and the second neutral cut-off valve 60 are housed in either the first region R1 or the second region R2. For example, when adding a new first neutral cut-off valve 40, the first neutral cut-off valve 40 can be housed in the second region R2 where the second neutral cut-off valve 60 is already installed. Therefore, there is no need to secure new space to house the additional first neutral cut-off valve 40. Thus, the size of the fluid pressure control device 100 can be kept down.

[0074] Furthermore, in the fluid pressure control device 100, the first neutral cut-off valve 40 has a spool 41 (first spool) that shuts off or opens the connection between the first neutral passage 11 and the tank T, and the second neutral cut-off valve 60 has a spool 61 (second spool) that shuts off or opens the connection between the second neutral passage 21 and the tank T, and the spool 41 (first spool) and the spool 61 (second spool) are arranged coaxially.

[0075] In this configuration, the spool 41 (first spool) of the first neutral cut-off valve 40 and the spool 61 (second spool) of the second neutral cut-off valve 60 are arranged coaxially. This makes it possible to suppress the increase in size of the fluid pressure control device 100 compared to the case where the spool 41 (first spool) of the first neutral cut-off valve 40 and the spool 61 (second spool) of the second neutral cut-off valve 60 are offset from each other.

[0076] Furthermore, in the fluid pressure control device 100, the spool 41 (first spool) and the spool 61 (second spool) are housed in the same through-hole (first housing hole 31) formed in the valve block 3.

[0077] In this configuration, the spool 41 (first spool) of the first neutral cut valve 40 and the spool 61 (second spool) of the second neutral cut valve 60 are housed in the same through hole (first housing hole 31) formed in the valve block 3. This reduces the number of machining steps compared to the case where the spool 41 (first spool) and the spool 61 (second spool) are provided in separate housing holes.

[0078] Furthermore, in the fluid pressure control device 100, the first circuit system 10 is provided downstream of the first neutral cut valve 40 in the first neutral passage 11 and further includes a first relief valve 81 that defines the maximum pressure in the first neutral passage 11, and the second circuit system 20 is provided downstream of the second neutral cut valve 60 in the second neutral passage 21 and further includes a second relief valve 82 that defines the maximum pressure in the second neutral passage 21, and the first neutral cut valve 40, the second neutral cut valve 60, the first relief valve 81 and the second relief valve 82 are provided in the same region of either the first region R1 or the second region R2.

[0079] In this configuration, the size of the valve block 3 can be suppressed by effectively utilizing the dead space that was previously located in the first region R1 or the second region R2.

[0080] 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.

[0081] In the above embodiment, the valve block 3 was described as being formed from a single member, but the valve block 3 may be constructed by stacking multiple blocks, or it may be configured to have valve blocks corresponding to the first region R1 and the second region R2, respectively. [Explanation of symbols]

[0082] 100... Fluid pressure control device, 3... Valve block, 10... First circuit system, 11... First neutral passage, 12... Supply passage, 13... First parallel passage, 13a... First parallel upstream passage, 13b... First parallel downstream passage, 16... Pilot passage, 17... Check valve, 18... Pilot passage, 20... Second circuit system, 21... Second neutral passage 23...Second parallel passage, 25...Control valve for straight-line travel, 26...Merge passage, 31...First housing hole (through hole), 40...First neutral cut-off valve, 41...Spool (first spool), 43...Pilot pressure chamber, 44...Return spring, 45...Pilot port, 50...Regeneration release valve, 60...Second neutral cut-off valve, 61...Spool (second spool) 63...Pilot pressure chamber, 64...Return spring, 65...Pilot port, 70...Flow control valve, 76...Check valve, 81...First relief valve, 82...Second relief valve, 90...Arm cylinder, 121...First travel control valve (first control valve), 122...Auxiliary control valve (first control valve), 123...Swivel control valve (first control valve), 124... • Boom 2nd speed control valve (1st control valve), 125... Arm 1st speed control valve (1st control valve), 221... 2nd travel control valve (2nd control valve), 222... Bucket control valve (2nd control valve), 223... Boom 1st speed control valve (2nd control valve), 224... Arm 2nd speed control valve (2nd control valve) P1... 1st pump, P2... 2nd pump, R1... 1st region, R2... 2nd region

Claims

1. A fluid pressure control device, A first circuit system having at least one first control valve connected to a first pump and controlling an actuator, A second circuit system having at least one second control valve connected to the second pump and controlling the actuator, The valve block comprises a first region in which the first control valve is housed and a second region in which the second control valve is housed, The first circuit system is, A first neutral passage that recirculates the working fluid of the first pump to the tank when all of the first control valves are in the neutral position, The system includes a first neutral cut-off valve provided downstream of the first control valve in the first neutral passage, which connects or disconnects the first neutral passage and the tank, The second circuit system is, A second neutral passage that recirculates the working fluid of the second pump to the tank when all of the second control valves are in the neutral position, The system includes a second neutral cut-off valve provided downstream of the second control valve in the second neutral passage, which connects or disconnects the second neutral passage and the tank, A fluid pressure control device characterized in that the first neutral cut-off valve and the second neutral cut-off valve are housed in either the first region or the second region.

2. A fluid pressure control device according to claim 1, The first neutral cut-off valve has a first spool that shuts off or opens the connection between the first neutral passage and the tank. The second neutral cut-off valve has a second spool that shuts off or opens the connection between the second neutral passage and the tank. A fluid pressure control device characterized in that the first spool and the second spool are arranged coaxially.

3. A fluid pressure control device according to claim 2, A fluid pressure control device characterized in that the first spool and the second spool are housed in the same through-hole formed in the valve block.

4. A fluid pressure control device according to any one of claims 1 to 3, The first circuit system is, The system further comprises a first relief valve located downstream of the first neutral cut-off valve in the first neutral passage, which defines the maximum pressure in the first neutral passage. The second circuit system is, Further comprising a second relief valve provided downstream of the second neutral cut-off valve in the second neutral passage, which defines the maximum pressure in the second neutral passage, A fluid pressure control device characterized in that the first neutral cut-off valve, the second neutral cut-off valve, the first relief valve, and the second relief valve are provided in the same region, either the first region or the second region.

Images