Valve device

Abstract

To increase a flow rate of working fluid led from a supply port to an actuator.SOLUTION: A valve device 100 is equipped with a main spool 170 that has supply passages 195, 196, and 197, and a supply side land part 171, and a valve block 10 that has a lead-out passage 123. The supply passage 195 communicates a supply port 121a with the lead-out passage 123 in a process that the main spool 170 moves from a neutral position toward one stroke end in an axial direction. The supply passage 196 communicates a supply port 121b with the lead-out passage 123 in a process that the main spool 170 moves from the neutral position toward the other stroke end in the axial direction. The supply passage 197 communicates the supply port 121b with the lead-out passage 123 in a process that the main spool 170 moves to the one stroke end, and communicates the supply port 121a with the lead-out passage 123 that the main spool 170 moves toward the other stroke end.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a valve device. [Background technology]

[0002] Patent Document 1 discloses a multiple selector valve including a valve body, a spool slidably incorporated in the valve body, a pair of supply ports connected to a pump, an inlet port formed between the pair of supply ports and communicating with one of the supply ports depending on the movement position of the spool, an actuator port communicating with an actuator, and a bridge passage through which fluid introduced to the inlet port is supplied and which communicates with the actuator port depending on the movement position of the spool. A first annular groove is provided approximately in the center of the spool, and notches are formed on both sides of the first annular groove.

[0003] In the multiple switching valve described in Patent Document 1, communication between the inlet port and the supply port is blocked when the spool is in the neutral position. When the spool moves to the right, one of the supply ports communicates with the inlet port via the first annular groove and the notch. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-8386 Summary of the Invention [Problem to be solved by the invention]

[0005] In the multiple directional control valve described in Patent Document 1, the flow rate of the working fluid flowing from one supply port to the inlet port is controlled by the opening area of the notch. However, the notch is provided on the outer peripheral surface of the spool, and the upper limit of the opening area of the notch is determined by the outer diameter of the spool. Therefore, in the multiple directional control valve described in Patent Document 1, there is an upper limit to how large the opening area of the notch can be. Therefore, in the multiple directional control valve described in Patent Document 1, it is difficult to increase the flow rate of the working fluid guided from the supply port through the inlet port to the actuator.

[0006] The present invention has been made in view of the above problems, and has an object to increase the flow rate of working fluid guided from a supply port to an actuator in a valve device. [Means for solving the problem]

[0007] The present invention provides a valve device for controlling the flow of working fluid supplied from a hydraulic pressure pump to an actuator, the valve device comprising: a spool movable in the axial direction; and a valve body slidably accommodating the spool; the valve body having first and second supply ports to which the working fluid discharged from the hydraulic pressure pump is respectively supplied, first and second actuator passages communicating with the actuator, a discharge passage communicating with a tank, and outlet passages for guiding the working fluid from the first and second supply ports to the first and second actuator passages; the spool has a first supply passage that guides the working fluid from the first supply port to the outlet passage as the spool moves and provides resistance to the flow of the working fluid passing through, a second supply passage that guides the working fluid from the second supply port to the outlet passage as the spool moves and provides resistance to the flow of the working fluid passing through, and a valve body slidably accommodating the first supply port, the outlet passage, and the second supply port. and a third supply passage that can connect the first supply port to the outlet passage and provide resistance to the working fluid passing through, and a land portion that can block communication between the first, second, and third supply passages and the outlet passage, wherein the land portion blocks communication between the first supply port and the outlet passage and between the second supply port and the outlet passage when the spool is in a neutral position, the first supply passage connects the first supply port to the outlet passage as the spool moves from the neutral position toward one stroke end in the axial direction, the second supply passage connects the second supply port to the outlet passage as the spool moves from the neutral position toward the other stroke end in the axial direction, and the third supply passage connects the second supply port to the outlet passage as the spool moves toward one stroke end, and connects the first supply port to the outlet passage as the spool moves toward the other stroke end.

[0008] In this invention, the spool has a third supply passage that connects the second supply port to the outlet passage at one stroke end and the first supply port to the outlet passage at the other stroke end. This allows hydraulic fluid to be guided to the outlet passage from both the first and second supply ports, rather than just one of them, regardless of whether the spool moves to either stroke end. This increases the flow rate of hydraulic fluid guided from the supply port to the actuator.

[0009] The present invention is characterized in that the valve body is provided with an accommodation hole that slidably accommodates the spool, the accommodation hole having a first supply port, a second supply port, and a discharge passage each opening therein, and the opening of the discharge passage is provided axially between the opening of the first supply port and the opening of the second supply port, and the working fluid is guided from the opening of the first supply port through the interior of the accommodation hole to the opening of the discharge passage, and the working fluid is guided from the opening of the second supply port through the interior of the accommodation hole to the opening of the discharge passage, both in the process of the spool moving toward one stroke end and in the process of the spool moving toward the other stroke end.

[0010] In this invention, the fluid force generated when the working fluid is guided from the first supply port to the outlet passage and the fluid force generated when the working fluid is guided from the second supply port to the outlet passage can cancel each other out.

[0011] The present invention is characterized in that the third supply passage has a communication notch that opens into the outer peripheral surface of the land portion and that can respectively communicate between the first supply port and the outlet passage and between the second supply port and the outlet passage.

[0012] In this aspect of the invention, the communication notch of the third supply passage, the first supply passage, and the second supply passage can communicate both the first and second supply ports with the outlet passage. [Effects of the Invention]

[0013] According to the present invention, the flow rate of the working fluid guided from the supply port to the actuator in the valve device can be increased. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view showing a valve device according to an embodiment of the present invention, illustrating a state in which a main spool is in a neutral position. [Figure 2] 1 is a cross-sectional view showing the valve device according to the embodiment of the present invention, illustrating a state in which the main spool has moved to a forward position. [Figure 3] 1 is a cross-sectional view showing a valve device according to an embodiment of the present invention, illustrating a state in which the main spool has moved to a retracted position. [Figure 4] FIG. 10 is an enlarged cross-sectional view showing a supply-side land portion of a main spool of a valve device according to a modified embodiment of the present invention, in a state where the main spool is in a neutral position. [Figure 5] 5 is an enlarged cross-sectional view showing an enlarged supply-side land portion of a main spool of a valve device according to a modified example of the embodiment of the present invention, and corresponds to FIG. 4. DETAILED DESCRIPTION OF THE INVENTION

[0015] A valve gear according to an embodiment of the present invention will be described with reference to the drawings. The valve gear is mounted on a work machine, such as a construction machine, agricultural machine, or industrial machine, that is equipped with a traveling device. The following describes an example of a valve gear mounted on a crawler-type hydraulic excavator as a work machine. While an example will be described in which hydraulic oil is used as a working fluid to drive the actuator of the hydraulic excavator, other fluids, such as hydraulic water, may also be used as the working fluid.

[0016] Although not shown, the hydraulic excavator includes a traveling unit, a swivel unit rotatably mounted on the upper part of the traveling unit, and an excavation unit mounted on the swivel unit. The traveling unit has crawlers. The crawlers are driven by a travel motor 111 serving as an actuator (described later), causing the hydraulic excavator to travel. The excavation unit includes a boom rotatably attached to the swivel unit, an arm rotatably attached to the boom, and a bucket rotatably attached to the arm.

[0017] The hydraulic excavator includes an engine (not shown), a pump 110 as a fluid pressure pump driven by the engine and discharging hydraulic oil, a valve device 100 that controls the flow of hydraulic oil supplied from the pump 110 to actuators for driving a traveling unit, a rotating unit, an excavating unit, etc., and a tank 119 to which the hydraulic oil is returned from the valve device 100. In this embodiment, the hydraulic excavator includes a plurality of valve devices 100 and a plurality of actuators, and the operation of each actuator is controlled by each valve device 100.

[0018] The valve device 100 will be described in detail with reference to FIGS. 1 to 3. In this embodiment, the valve device 100 will be described as an actuator that controls the operation of a traveling motor 111, which is a hydraulic motor for driving a traveling part. FIGS. 1 to 3 are cross-sectional views showing the valve device 100, and FIG. 1 shows a state in which the main spool 170 is in a neutral position. FIG. 2 shows a state in which the main spool 170 has moved to a forward position (to the left in FIGS. 1 to 3 from the neutral position). FIG. 3 shows a state in which the main spool 170 has moved to a backward position (to the right in FIGS. 1 to 3 from the neutral position). Note that FIGS. 2 and 3 omit illustrations of the pump 110, the traveling motor 111, the tank 119, and a first pilot pressure chamber 135a, a second pilot pressure chamber 135b, and the like, which will be described later.

[0019] As shown in FIG. 1, the valve device 100 includes a main spool 170 as a spool that is movable in the axial direction, a compensator spool 180 that moves in a direction perpendicular to the axial direction of the main spool 170, and a valve block 10 as a valve body that slidably houses the main spool 170 and the compensator spool 180.

[0020] The main spool 170 moves in the axial direction based on a travel operation command. The travel operation command corresponds to a pilot pressure that is output from a pilot pressure output portion (not shown) to a first pilot pressure chamber 135a or a second pilot pressure chamber 135b (described later) in accordance with the amount of operation of a travel operation lever (not shown).

[0021] The valve block 10 is provided with a main housing hole 150 as a housing hole that slidably houses a main spool 170, and a sub housing hole 160 that slidably houses a compensator spool 180. The valve block 10 and the main spool 170 are structured in a generally symmetrical shape.

[0022] The valve device 100 also includes a first pilot pressure chamber 135a and a second pilot pressure chamber 135b that control the drive of the main spool 170, a centering spring 137 that is provided in the first pilot pressure chamber 135a and that urges the main spool 170 along its axial direction, and a position determining portion 138 that determines the position of the other stroke end of the main spool 170, which will be described later.

[0023] The first pilot pressure chamber 135a and the second pilot pressure chamber 135b are connected to the tank 119, and when no pilot pressure is applied to the first pilot pressure chamber 135a and the second pilot pressure chamber 135b, the main spool 170 is held in a neutral position by the biasing force of the centering spring 137. When pilot pressure is applied to the first pilot pressure chamber 135a, the main spool 170 moves from the neutral position to the left in FIG. 1 and is switched to the forward position. When the main spool 170 is switched to the forward position, hydraulic oil is supplied to the traveling motor 111 so that the hydraulic excavator moves forward. When pilot pressure is applied to the second pilot pressure chamber 135b, the main spool 170 moves from the neutral position to the right in FIG. 1 and is switched to the reverse position. When the main spool 170 is switched to the reverse position, hydraulic oil is supplied to the traveling motor 111 so that the hydraulic excavator moves backward.

[0024] The valve block 10 has first and second supply ports 121a, 121b to which hydraulic oil discharged from the pump 110 is respectively supplied, first and second actuator passages 125a, 125b communicating with the travel motor 111, a discharge passage 129 communicating with the tank 119, and a lead-out passage 123 that leads the hydraulic oil from the first and second supply ports 121a, 121b to the first and second actuator passages 125a, 125b. The first and second supply ports 121a, 121b, the first and second actuator passages 125a, 125b, the discharge passage 129, and the lead-out passage 123 each open to the main accommodating hole 150.

[0025] The travel motor 111 is driven by the valve device 100 supplying hydraulic oil from the pump 110 through the first and second actuator passages 125a and 125b.

[0026] The hydraulic oil supplied from the pump 110 to the first and second supply ports 121a, 121b is guided to the traveling motor 111 through the outlet passage 123 and the first actuator passage 125a or through the outlet passage 123 and the second actuator passage 125b. The hydraulic oil from the traveling motor 111 is also discharged from the first and second actuator passages 125a, 125b through a discharge passage 129 to the tank 119.

[0027] The outlet passage 123 has a first passage 123a extending radially from the main accommodating hole 150, and second and third passages 123b, 123c extending in two directions from the first passage 123a. The second and third passages 123b, 123c form a bridge-like shape in the outlet passage 123, forming a so-called bridge passage.

[0028] A part of the sub-housing hole 160 is formed in the first passage 123a of the outlet passage 123. The first passage 123a communicates with the main housing hole 150 and the sub-housing hole 160. A compensator spool 180 is interposed between the second and third passages 123b, 123c. One end of each of the second and third passages 123b, 123c communicates with the main housing hole 150, and the other end of each of the second and third passages 123b, 123c communicates with the first passage 123a and the sub-housing hole 160.

[0029] The first actuator passage 125a communicates with a first actuator port 126a opening on the outer peripheral surface of the valve block 10 and the main accommodating bore 150, and the second actuator passage 125b communicates with a second actuator port 126b opening on the outer peripheral surface of the valve block 10 and the main accommodating bore 150. In addition, the discharge passage 129 communicates with the vicinity of both ends of the main accommodating bore 150 in the axial direction and with the tank 119.

[0030] 1 , the main accommodating hole 150 communicates with each passage and port in the following order: the discharge passage 129, the first actuator passage 125a, the second passage 123b of the discharge passage 123, the first supply port 121a, the first passage 123a of the discharge passage 123, the second supply port 121b, the third passage 123c of the discharge passage 123, the second actuator passage 125b, and the discharge passage 129. In other words, in the main accommodating hole 150, the opening of the first passage 123a of the discharge passage 123 is provided between the opening of the first supply port 121a and the opening of the second supply port 121b in the axial direction. Note that the term "opening of the discharge passage" in the claims refers to the opening of the first passage 123a of the discharge passage 123.

[0031] The main spool 170 has a plurality of cylindrical lands that come into sliding contact with the inner circumferential surface of the main housing hole 150. Specifically, the main spool 170 has a supply-side land 171 provided at the axial center of the main spool 170, first and second outlet-side land portions 172a, 172b provided so that the supply-side land 171 is located between them, and first and second discharge-side land portions 173a, 173b provided so that the first and second outlet-side land portions 172a, 172b are located between them. The supply-side land portion 171 corresponds to the "land portion" in the claims.

[0032] The land portions are arranged in the following order from one axial end (right side in Figure 1) to the other axial end (left side in Figure 1): first discharge side land portion 173a, first outlet side land portion 172a, supply side land portion 171, second outlet side land portion 172b, and second discharge side land portion 173b.

[0033] The outer peripheral surface of the supply-side land portion 171 can block communication between the first and second supply ports 121a, 121b and the first passage 123a of the discharge passage 123. The outer peripheral surface of the first discharge-side land portion 172a can block communication between the second passage 123b of the discharge passage 123 and the first actuator passage 125a, and the outer peripheral surface of the second discharge-side land portion 172b can block communication between the third passage 123c of the discharge passage 123 and the second actuator passage 125b. The outer peripheral surface of the first discharge-side land portion 173a can block communication between the first actuator passage 125a and the discharge passage 129, and the outer peripheral surface of the second discharge-side land portion 173b can block communication between the second actuator passage 125b and the discharge passage 129.

[0034] The second discharge-side land portion 173b contacts the inner wall of the second pilot pressure chamber 135b to define one stroke end of the main spool 170. In addition, the first discharge-side land portion 173a is provided with a protrusion 174 that protrudes in the axial direction. The protrusion 174 contacts the position determining portion 138 to define the other stroke end of the main spool 170.

[0035] Annular grooves are provided between each land. A first annular groove 175 is provided between the supply-side land 171 and the first outlet-side land 172a, facing one end of the supply-side land 171. A second annular groove 176 is provided between the supply-side land 171 and the second outlet-side land 172b, facing the other end of the supply-side land 171. A third annular groove 177 is provided between the first outlet-side land 172a and the first discharge-side land 173a. A fourth annular groove 178 is provided between the second outlet-side land 172b and the second discharge-side land 173b.

[0036] The supply side land portion 171 is provided with a first notch 191 that opens into the first annular groove 175, a second notch 192 that opens into the second annular groove 176, and a communicating notch 193 that opens into the outer peripheral surface of the supply side land portion 171.

[0037] The first notches 191 are provided on the outer peripheral surface of the supply-side land portion 171, and extend from one end of the supply-side land portion 171 in the axial direction of the main spool 170, with a plurality of first notches 191 provided at equal intervals in the circumferential direction. The first notches 191 do not all have the same length in the axial direction of the main spool 170, and some of the first notches 191 are provided with a different length in the axial direction of the main spool 170 than the other first notches 191. The first notches 191 and the first annular groove 175 form a first supply passage 195 that guides the hydraulic oil from the first supply port 121a to the outlet passage 123 as the main spool 170 moves, and that provides resistance to the flow of the hydraulic oil passing through.

[0038] When the main spool 170 is in the neutral position, the first notch 191 faces the first supply port 121a but does not face the first passage 123a of the outlet passage 123. Therefore, when the main spool 170 is in the neutral position, the first supply passage 195 does not communicate between the first supply port 121a and the outlet passage 123. As shown in FIG. 2, when the main spool 170 moves to the forward position (the left side in FIGS. 1 to 3), that is, from the neutral position to one stroke end in the axial direction, the first annular groove 175 faces the first supply port 121a, and the first notch 191 faces the first passage 123a of the outlet passage 123, thereby communicating between the first supply port 121a and the outlet passage 123. In other words, the first supply passage 195 communicates between the first supply port 121a and the outlet passage 123 as the main spool 170 moves from the neutral position toward one stroke end in the axial direction. Specifically, one stroke end refers to a state in which the second discharge-side land portion 173b of the main spool 170 contacts the inner wall of the second pilot pressure chamber 135b. Note that only one first notch 191 may be provided, or multiple first notches 191 may be provided at different intervals in the circumferential direction. Also, multiple first notches 191 may be provided, all of which have the same shape.

[0039] The second notches 192 are provided on the outer peripheral surface of the supply-side land portion 171, extend from the other end of the supply-side land portion 171 in the axial direction of the main spool 170, and are provided at equal intervals in the circumferential direction. The second notches 192 do not all have the same length in the axial direction of the main spool 170, and some of the second notches 192 are provided with a different length in the axial direction of the main spool 170 than the other second notches 192. The second notches 192 and the second annular groove 176 form a second supply passage 196 that guides the hydraulic oil from the second supply port 121b to the outlet passage 123 as the main spool 170 moves and provides resistance to the flow of the hydraulic oil passing through.

[0040] As shown in FIG. 1, when the main spool 170 is in the neutral position, the second notch 192 faces the second supply port 121b but does not face the first passage 123a of the outlet passage 123. Therefore, when the main spool 170 is in the neutral position, the second supply passage 196 does not communicate between the second supply port 121b and the outlet passage 123. As shown in FIG. 3, when the main spool 170 moves to the retracted position (the right side in FIGS. 1 to 3), that is, from the neutral position to the other stroke end in the axial direction, the second annular groove 176 faces the second supply port 121b, and the second notch 192 faces the first passage 123a of the outlet passage 123, thereby communicating between the second supply port 121b and the outlet passage 123. In other words, the second supply passage 196 communicates between the second supply port 121b and the outlet passage 123 as the main spool 170 moves from the neutral position toward the other stroke end in the axial direction. Specifically, the other stroke end is a state in which the protruding portion 174 of the main spool 170 contacts the position determining portion 138. Note that only one second notch 192 may be provided, or multiple second notches 192 may be provided at different intervals in the circumferential direction. Also, multiple second notches 192 may be provided, all of which have the same shape.

[0041] The communication notch 193 is provided to extend axially between the first notch 191 and the second notch 192 in the axial direction of the main spool 170, and can respectively communicate between the first supply port 121a and the outlet passage 123, and between the second supply port 121b and the outlet passage 123. The communication notch 193 forms a third supply passage 197 that can respectively communicate between the first supply port 121a and the outlet passage 123, and between the second supply port 121b and the outlet passage 123, and that applies resistance to the hydraulic oil passing through. The communication notch 193 does not open to the first annular groove 175 or the second annular groove 176.

[0042] 1, when the main spool 170 is in the neutral position, the communication notch 193 faces the first passage 123a of the outlet passage 123, but does not face the first supply port 121a or the second supply port 121b. Therefore, when the main spool 170 is in the neutral position, the third supply passage 197 does not communicate between the first supply port 121a and the outlet passage 123, and between the second supply port 121b and the outlet passage 123.

[0043] As shown in Fig. 2, when the main spool 170 moves to the forward position, the communication notch 193 faces the second supply port 121b and the first passage 123a of the outlet passage 123, and the third supply passage 197 communicates between the second supply port 121b and the outlet passage 123. In other words, the third supply passage 197 communicates between the second supply port 121b and the outlet passage 123 through the inside of the main housing bore 150 as the main spool 170 moves from the neutral position toward one stroke end in the axial direction. As shown in Fig. 3, when the main spool 170 moves to the retracted position, the communication notch 193 faces the first supply port 121a and the first passage 123a of the outlet passage 123, and the third supply passage 197 communicates between the first supply port 121a and the outlet passage 123. In other words, the third supply passage 197 communicates between the first supply port 121a and the outlet passage 123 through the inside of the main housing hole 150 while the main spool 170 moves from the neutral position toward the other stroke end in the axial direction. Only one communication notch 193 may be provided, or multiple communication notches 193 may be provided at equal or different intervals in the circumferential direction.

[0044] As described above, when the main spool 170 is in the neutral position, communication between the first supply port 121a and the outlet passage 123 and between the second supply port 121b and the outlet passage 123 is blocked. As shown in Fig. 2, when the main spool 170 moves to the forward position, the first supply passage 195 communicates between the first supply port 121a and the outlet passage 123, and the third supply passage 197 communicates between the second supply port 121b and the outlet passage 123. As shown in Fig. 3, when the main spool 170 moves to the retracted position, the third supply passage 197 communicates between the first supply port 121a and the outlet passage 123, and the second supply passage 196 communicates between the second supply port 121b and the outlet passage 123. That is, in the valve device 100 of this embodiment, when the main spool 170 moves from the neutral position to both stroke ends, both the first and second supply ports 121a, 121b and the outlet passage 123 communicate with each other.

[0045] As described above, in the valve device 100, in both the process in which the main spool 170 moves toward the forward position (one stroke end) and the process in which it moves toward the retracted position (the other stroke end), hydraulic oil is guided from the opening of the first supply port 121a through the inside of the main accommodating hole 150 toward the opening of the outlet passage 123, and hydraulic oil is guided from the opening of the second supply port 121b through the inside of the main accommodating hole 150 toward the opening of the outlet passage 123. In other words, the flow of hydraulic oil from the first supply port 121a to the outlet passage 123 and the flow of hydraulic oil from the second supply port 121b to the outlet passage 123 inside the main accommodating hole 150 are opposite to each other in the axial direction of the main spool 170. This allows the fluid force acting on the main spool 170 from the hydraulic oil guided from the first supply port 121a to the outlet passage 123 and the fluid force acting on the main spool 170 from the hydraulic oil guided from the second supply port 121b to the outlet passage 123 to cancel each other out. This improves the hysteresis of the main spool 170, and improves the operation of the valve device 100.

[0046] The first notch 191, the second notch 192, and the communicating notch 193 may have the same or different cross-sectional areas perpendicular to the axial direction of the main spool 170. Furthermore, when the main spool 170 moves toward the forward position, the timing at which the third supply passage 197 connects the second supply port 121b to the outlet passage 123 may be the same as or different from the timing at which the first supply passage 195 connects the first supply port 121a to the outlet passage 123. Furthermore, when the main spool 170 moves toward the retracted position, the timing at which the third supply passage 197 connects the first supply port 121a to the outlet passage 123 may be the same as or different from the timing at which the second supply passage 196 connects the second supply port 121b to the outlet passage 123.

[0047] As described above, the supply-side land portion 171 is provided with the first notch 191, the second notch 192, and the communicating notch 193. The supply-side land portion 171 blocks communication between the first supply port 121a and the outlet passage 123 and between the second supply port 121b and the outlet passage 123 by using an area of the outer circumferential surface that does not have the first notch 191, the second notch 192, and the communicating notch 193. In other words, the supply-side land portion 171 can block communication between the first, second, and third supply passages 195, 196, and 197 and the outlet passage 123, and blocks communication between the first supply port 121a and the outlet passage 123 and between the second supply port 121b and the outlet passage 123 when the main spool 170 is in the neutral position.

[0048] The compensator spool 180 adjusts the load between the actuators when a plurality of the actuators controlled by the plurality of valve devices 100 are simultaneously operated. In this manner, a load sensing system using the compensator spool 180 is adopted in the plurality of valve devices 100 provided in the hydraulic excavator in this embodiment.

[0049] The compensator spool 180 is disposed so that one end (the lower end in FIGS. 1 to 3) faces the first passage 123a of the outlet passage 123, and the other end (the upper end in FIGS. 1 to 3) faces a maximum load pressure chamber 185 to which the maximum load pressure (the highest load pressure among the load pressures of the actuators controlled by the multiple valve devices 100) is guided. The compensator spool 180 compensates so that the pressure in the first passage 123a of the outlet passage 123 is higher than the maximum load pressure by a predetermined value. As a result, when the actuators are driven simultaneously by the multiple valve devices 100, hydraulic oil can be supplied at a flow rate corresponding to the amount of movement of the main spool 170 of the valve device 100, regardless of the magnitude of the load pressure of the actuators.

[0050] The compensator spool 180 is provided with a throttle portion 181 that applies resistance to the hydraulic oil passing from the first passage 123a to the second passage 123b and the third passage 123c of the outlet passage 123 in the initial stage of movement of the compensator spool 180 toward the maximum load pressure chamber 185. The opening degree of the throttle portion 181 relative to the second passage 123b and the third passage 123c increases as the compensator spool 180 moves toward the maximum load pressure chamber 185.

[0051] The compensator spool 180 is provided with a pressure introducing portion 182 whose opening to the second passage 123b and the third passage 123c is variable depending on the position of the compensator spool 180. The opening of the pressure introducing portion 182 to the second passage 123b and the third passage 123c decreases as the compensator spool 180 moves toward the maximum load pressure chamber 185.

[0052] Furthermore, a high-pressure selection valve 183 is incorporated into the compensator spool 180. The high-pressure selection valve 183 is disposed so that one end (the lower end in FIGS. 1 to 3) faces the pressure introduction chamber 184 and the other end (the upper end in FIGS. 1 to 3) faces the maximum load pressure chamber 185. The high-pressure selection valve 183 maintains a closed state when the pressure in the maximum load pressure chamber 185 is higher than the pressure in the pressure introduction chamber 184. On the other hand, the high-pressure selection valve 183 opens when the pressure in the pressure introduction chamber 184 is higher than the pressure in the maximum load pressure chamber 185, and introduces the pressure in the pressure introduction chamber 184 to the maximum load pressure chamber 185 of the other valve device 100.

[0053] The operation of the valve device 100 according to this embodiment will be described with reference to FIGS.

[0054] When the operator of the hydraulic excavator operates a travel control lever (not shown) provided in the cab, pilot pressure as a travel operation command acts on the first pilot pressure chamber 135a or the second pilot pressure chamber 135b of the valve device 100. To travel straight ahead, the operator tilts the left travel control lever toward the forward movement side and tilts the right travel control lever toward the forward movement side. Below, we will explain in detail the operation of the main spool 170 and the compensator spool 180, and the flow of hydraulic oil within the valve device 100, as the operation of the valve device 100 when the left and right travel control levers (not shown) are simultaneously operated toward the forward movement side to travel the hydraulic excavator straight ahead.

[0055] 1, when the travel control lever is held in the neutral position, the main spool 170 is held in the neutral position. With the main spool 170 in the neutral position, the outer peripheral surface of the supply-side land portion 171 blocks communication between the first supply port 121a and the outlet passage 123, and between the second supply port 121b and the outlet passage 123. In addition, the outer peripheral surface of the first discharge-side land portion 173a blocks communication between the first actuator passage 125a and the discharge passage 129, and the outer peripheral surface of the second discharge-side land portion 173b blocks communication between the second actuator passage 125b and the discharge passage 129.

[0056] Furthermore, when the main spool 170 is in the neutral position, the outer surface of the first outlet side land portion 172a blocks communication between the second passage 123b of the outlet passage 123 and the first actuator passage 125a, and the outer surface of the second outlet side land portion 172b blocks communication between the third passage 123c of the outlet passage 123 and the second actuator passage 125b.

[0057] When the travel control lever is started to be operated toward the forward direction, pilot pressure acts on the first pilot pressure chamber 135a, and the main spool 170 moves to the forward position. As shown in FIG. 2, when the main spool 170 moves to the forward position (to the left from the neutral position in FIGS. 1 to 3), the first supply port 121a and the first passage 123a of the outlet passage 123 communicate with each other through the first supply passage 195 (specifically, the first annular groove 175 and the first notch 191). Furthermore, the second supply port 121b and the first passage 123a of the outlet passage 123 communicate with each other through the third supply passage 197 (specifically, the communication notch 193). In this way, hydraulic oil is guided to the first passage 123a from both the first and second supply ports 121a, 121b, and therefore the amount of hydraulic oil guided from the first and second supply ports 121a, 121b to the first passage 123a is increased compared to when hydraulic oil is guided from one of the first and second supply ports 121a, 121b.

[0058] Furthermore, hydraulic oil from the first and second supply ports 121a, 121b is throttled by the first notch 191 and the communicating notch 193 before being guided to the first passage 123a. If hydraulic oil were guided from the first and second supply ports 121a, 121b to the first passage 123a without passing through a throttle such as a notch, a large amount of hydraulic oil would be guided to the first passage 123a the moment the first supply port 121a and the first passage 123a and the second supply port 121b and the first passage 123a were connected to each other, making it impossible to control the flow rate of hydraulic oil flowing into the first passage 123a. In contrast, in the valve device 100 of this embodiment, the first notch 191 and the communicating notch 193 increase the amount of hydraulic oil guided from the first and second supply ports 121a, 121b to the first passage 123a while controlling the flow rate of hydraulic oil flowing into the first passage 123a.

[0059] When hydraulic oil is introduced into the first passage 123a of the outlet passage 123, the pressure in the first passage 123a causes the compensator spool 180 to move upward in the figure against the pressure in the maximum load pressure chamber 185. When the compensator spool 180 moves upward in the figure, the opening of the throttle portion 181 increases. Therefore, as the opening of the throttle portion 181 increases, the flow rate of hydraulic oil introduced from the first passage 123a to the second passage 123b of the outlet passage 123 increases.

[0060] When the main spool 170 is in the forward position, the second passage 123b of the outlet passage 123 and the first actuator passage 125a communicate with each other through the third annular groove 177 of the main spool 170. Therefore, the hydraulic oil guided to the second passage 123b is guided to the first actuator passage 125a through the third annular groove 177.

[0061] The hydraulic oil guided to the first actuator passage 125a is supplied to the travel motor 111 through the first actuator port 126a, causing the travel motor 111 to rotate. The hydraulic oil discharged from the travel motor 111 is guided to the second actuator passage 125b through the second actuator port 126b. When the main spool 170 is in the forward position, the second actuator passage 125b and the discharge passage 129 communicate with each other through the fourth annular groove 178 of the main spool 170. Therefore, the hydraulic oil guided to the second actuator passage 125b is guided to the discharge passage 129 through the fourth annular groove 178 and discharged to the tank 119.

[0062] When the left or right travel control lever is operated to the reverse side, the movement of the main spool 170 is opposite to that described above. That is, as shown in FIG. 3, when the main spool 170 moves to the reverse position (to the right in FIGS. 1 to 3 from the neutral position), the first supply port 121a and the first passage 123a of the outlet passage 123 communicate with each other through the third supply passage 197 (specifically, the communication notch 193). Furthermore, the second supply port 121b and the first passage 123a of the outlet passage 123 communicate with each other through the second supply passage 196 (specifically, the second annular groove 176 and the second notch 192). Then, hydraulic oil is guided from the first passage 123a of the outlet passage 123 to the second actuator passage 125b through the third passage 123c and the fourth annular groove 178 of the main spool 170. On the other hand, the hydraulic oil discharged from the traveling motor 111 is guided to the discharge passage 129 through the first actuator port 126a, the first actuator passage 125a, and the third annular groove 177, and is then discharged into the tank 119.

[0063] As described above, in the valve device 100 of this embodiment, the main spool 170 has the third supply passage 197 that can respectively connect the first supply port 121a and the outlet passage 123 and the second supply port 121b and the outlet passage 123. As a result, when the main spool 170 moves to both stroke ends, working fluid is guided to the outlet passage 123 from both the first and second supply ports 121a, 121b, rather than just one of them. This increases the flow rate of working fluid guided from the first and second supply ports 121a, 121b through the outlet passage 123 to the traveling motor 111. This increases the output of the traveling motor 111.

[0064] Furthermore, in the valve device 100 of this embodiment, the first supply port 121a and the discharge passage 123, and the second supply port 121b and the discharge passage 123 are respectively connected to each other by the first notch 191, the second notch 192, and the communicating notch 193. Therefore, the hydraulic oil from the first and second supply ports 121a, 121b is throttled and guided by the first notch 191, the second notch 192, and the communicating notch 193, so that the flow rate of the hydraulic oil flowing into the first passage 123a of the discharge passage 123 can be controlled by the first notch 191, the second notch 192, and the communicating notch 193, while the flow rate of the hydraulic oil flowing into the first passage 123a can be controlled.

[0065] According to the above-described embodiment, the following advantageous effects are achieved.

[0066] The valve device 100 has a third supply passage 197 that connects the second supply port 121b to the outlet passage 123 when the main spool 170 moves toward the forward position (one stroke end) and connects the first supply port 121a to the outlet passage 123 when the main spool 170 moves toward the retracted position (the other stroke end). As a result, when the main spool 170 moves to both stroke ends, working fluid is guided to the outlet passage 123 from both the first and second supply ports 121a, 121b rather than just one of them. This increases the flow rate of working oil guided from the first and second supply ports 121a, 121b through the outlet passage 123 to the traveling motor 111.

[0067] In the valve device 100, during both the process of the main spool 170 moving toward the forward position and the process of moving toward the retracted position, hydraulic oil is guided from the opening of the first supply port 121a to the opening of the outlet passage 123 through the inside of the main accommodating bore 150, and hydraulic oil is guided from the opening of the second supply port 121b to the opening of the outlet passage 123 through the inside of the main accommodating bore 150. In other words, the flow of hydraulic oil from the first supply port 121a to the outlet passage 123 and the flow of hydraulic oil from the second supply port 121b to the outlet passage 123 within the main accommodating bore 150 are opposite to each other in the axial direction of the main spool 170. This allows the fluid force acting on the main spool 170 from the hydraulic oil guided from the first supply port 121a to the outlet passage 123 and the fluid force acting on the main spool 170 from the hydraulic oil guided from the second supply port 121b to the outlet passage 123 to cancel each other out, improving the hysteresis of the main spool 170 and improving the operation of the valve device 100.

[0068] The following modified examples are also within the scope of the present invention, and it is possible to combine the configuration shown in the modified example with the configuration described in the above embodiment, to combine the configurations described in the different embodiments above, or to combine the configurations described in the different modified examples below.

[0069] <Modification> In the above embodiment, the third supply passage 197 has a communication notch 193 formed on the outer circumferential surface of the supply-side land portion 171. Alternatively, as shown in FIG. 4, the third supply passage 197 may have a first through hole 293a that penetrates the main spool 170 in the axial direction and a plurality of second through holes 293b that communicate with the first through hole 293a and penetrate the supply-side land portion 171 in the radial direction. A plurality of second through holes 293b are provided lined up in the axial direction of the main spool 170. The plurality of second through holes 293b communicate with each other through the first through hole 293a. When the main spool 170 moves to the forward position (left side in FIG. 4), the second supply port 121b and the outlet passage 123 communicate with each other through the leftmost second through hole 293b and the rightmost second through hole 293b in FIG. 4. Furthermore, when the main spool 170 moves to the retracted position (the right side in FIG. 4), the first supply port 121a and the outlet passage 123 communicate with each other through the rightmost second through hole 293b and the leftmost second through hole 293b in FIG. 4.

[0070] 5, the supply-side land portion 171 of the main spool 170 may be provided with a small diameter portion 171a, a pair of large diameter portions 171b positioned so as to sandwich the small diameter portion 171a, and a pair of tapered portions 171c provided between the small diameter portion 171a and the pair of large diameter portions 171b. In this case, instead of the communicating notch 193, the third supply passage 197 may have a pair of first through holes 393a radially penetrating the pair of large diameter portions 171b, respectively, and a plurality of second through holes 393b communicating with each of the pair of first through holes 393a and opening into the tapered portion 171c. Each of the plurality of second through holes 393b communicates with one of the pair of first through holes 393a and opens into the tapered portion 171c. When the main spool 170 moves to the forward position, the second supply port 121b and the outlet passage 123 communicate with each other through the first through hole 393a on the left side in Fig. 5 and the second through hole 393b communicating with the first through hole 393a. When the main spool 170 moves to the retracted position, the first supply port 121a and the outlet passage 123 communicate with each other through the first through hole 393a on the right side in Fig. 5 and the second through hole 393b communicating with the first through hole 393a. These configurations also provide the same effects as the above embodiment.

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

[0072] The valve device 100 controls the flow of hydraulic fluid supplied from a hydraulic pressure pump 110 to a traveling motor 111 serving as an actuator. The valve device 100 includes a main spool 170 as a spool that is movable in the axial direction, and a valve block 10 as a valve body that slidably houses the main spool 170. The valve block 10 includes first and second supply ports 121a, 121b to which the hydraulic fluid discharged from the hydraulic pressure pump 110 is supplied, first and second actuator passages 125a, 125b that communicate with the traveling motor 111, a discharge passage 129 that communicates with a tank 119, and a valve block 10 that discharges the hydraulic fluid from the first and second supply ports 121a, 121b to the first and second actuator passages 125a, 125b. The main spool 170 has a first supply passage 195 that guides the working fluid from the first supply port 121a to the outlet passage 123 as the main spool 170 moves and provides resistance to the flow of the working fluid passing through, a second supply passage 196 that guides the working fluid from the second supply port 121b to the outlet passage 123 as the main spool 170 moves and provides resistance to the flow of the working fluid passing through, a third supply passage 197 that can respectively communicate between the first supply port 121a and the outlet passage 123 and between the second supply port 121b and the outlet passage 123 and provides resistance to the working fluid passing through, and the first, second, and third supply passages 195, 196,The supply-side land portion 171 is a land portion that can block communication between the first supply port 121a and the outlet passage 123 and between the second supply port 121b and the outlet passage 123 when the main spool 170 is in the neutral position, and the first supply passage 195 connects the first supply port 121a and the outlet passage 123 when the main spool 170 moves from the neutral position toward one stroke end in the axial direction. The second supply passage 196 communicates between the second supply port 121b and the outlet passage 123 as the main spool 170 moves from the neutral position toward the other stroke end in the axial direction, and the third supply passage 197 communicates between the second supply port 121b and the outlet passage 123 as the main spool 170 moves toward one stroke end, and communicates between the first supply port 121a and the outlet passage 123 as the main spool 170 moves toward the other stroke end.

[0073] In this configuration, the main spool 170 has a third supply passage 197 that connects the second supply port 121b to the outlet passage 123 at one stroke end and connects the first supply port 121a to the outlet passage 123 at the other stroke end. As a result, when the main spool 170 moves to both stroke ends, the working fluid is guided to the outlet passage 123 from both the first and second supply ports 121a, 121b, rather than from just one of them. This increases the flow rate of the working fluid guided from the supply ports 121a, 121b to the actuator.

[0074] In the valve device 100, the valve block 10 is provided with a main accommodating hole 150 as an accommodating hole that slidably accommodates the main spool 170, and the main accommodating hole 150 has a first supply port 121a, a second supply port 121b, and an outlet passage 123 each opening therein, and the opening of the outlet passage 123 is provided axially between the first supply port 121a and the second supply port 121b, so that during both the process of the main spool 170 moving toward one stroke end and the process of the main spool 170 moving toward the other stroke end, hydraulic oil is guided from the opening of the first supply port 121a through the inside of the main accommodating hole 150 to the opening of the outlet passage 123, and hydraulic oil is guided from the opening of the second supply port 121b through the inside of the main accommodating hole 150 to the opening of the outlet passage 123.

[0075] In this configuration, the fluid force generated when the working fluid is guided from the first supply port 121a to the outlet passage 123 and the fluid force generated when the working fluid is guided from the second supply port 121b to the outlet passage 123 can cancel each other out.

[0076] The valve device 100 has a third supply passage 197 that opens to the outer peripheral surface of the supply side land portion 171 and has a communication notch 193 that can communicate between the first supply port 121a and the outlet passage 123, and between the second supply port 121b and the outlet passage 123, respectively.

[0077] In this configuration, the communication notch 193 of the third supply passage 197, the first supply passage 195, and the second supply passage 196 allow communication between both the first and second supply ports 121a, 121b and the outlet passage 123.

[0078] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments. [Explanation of symbols]

[0079] 10 valve block, 100 valve device, 110 pump (fluid pressure pump), 111 travel motor (actuator), 119 tank, 121a first supply port, 121b second supply port, 123 outlet passage, 125a first actuator passage, 125b second actuator passage, 129 discharge passage, 150 main accommodating hole (accommodating hole), 170 main spool (spool), 171 supply side land portion (land portion), 175 first annular groove, 176 second annular groove, 193 communicating notch, 195 first supply passage, 196 second supply passage, 197 third supply passage

Claims

1. A valve device for controlling the flow of hydraulic fluid supplied from a hydraulic pump to an actuator, a spool that is axially movable; a valve body that slidably accommodates the spool, The valve body is first and second supply ports to which the working fluid discharged from the fluid pressure pump is supplied, respectively; first and second actuator passages communicating with the actuator; a discharge passage communicating with the tank; an outlet passage that guides the hydraulic fluid from the first and second supply ports to the first and second actuator passages, The spool is a first supply passage that guides the working fluid from the first supply port to the outlet passage as the spool moves and that applies resistance to the flow of the working fluid passing through the first supply passage; a second supply passage that guides the working fluid from the second supply port to the outlet passage as the spool moves and that applies resistance to the flow of the working fluid passing through the second supply passage; a third supply passage that can respectively connect the first supply port and the outlet passage and the second supply port and the outlet passage and that applies resistance to the working fluid passing through; a land portion that can block communication between the first, second, and third supply passages and the outlet passage, When the spool is in a neutral position, the land portion blocks communication between the first supply port and the outlet passage and between the second supply port and the outlet passage, the first supply passage communicates the first supply port with the outlet passage as the spool moves from the neutral position toward one stroke end in the axial direction, the second supply passage communicates the second supply port with the outlet passage during a process in which the spool moves from the neutral position toward the other stroke end in the axial direction, the third supply passage connects the second supply port to the outlet passage when the spool moves toward the one stroke end, and connects the first supply port to the outlet passage when the spool moves toward the other stroke end.

2. 2. The valve device according to claim 1, The valve body is provided with a receiving hole for slidably receiving the spool, the first supply port, the second supply port, and the discharge passage each open into the accommodation hole, and an opening of the discharge passage is provided between an opening of the first supply port and an opening of the second supply port in the axial direction, a valve device characterized in that, during both the process of the spool moving toward the one stroke end and the process of the spool moving toward the other stroke end, working fluid is guided from the opening of the first supply port toward the opening of the outlet passage through the interior of the accommodating hole, and working fluid is guided from the opening of the second supply port toward the opening of the outlet passage through the interior of the accommodating hole.

3. The valve device according to claim 1 or 2, the third supply passage has a communication notch that opens into the outer peripheral surface of the land portion and that can respectively connect the first supply port to the outlet passage and the second supply port to the outlet passage.

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