Control valve

Abstract

A control valve (100) has four positions: a neutral location; a first switching location; a second switching location; and a third switching location at which a main spool (170) is located when having been further stroked from the second switching location, with which a first actuator port (125a) and a first tank port (128a) are in communication, and with which a second actuator port (125b) and a second tank port (128b) are in communication. The main spool (170) has a notch (193) that is capable of making the second actuator port (125b) and the second tank port (128b) in communication with each other at the third switching location in accordance with the movement of the main spool (170). A second spacer (20b) that has an insertion hole (21b) into which the main spool (170) is inserted is attached to the notch (193) side of a valve body (10).

Description

Control valve

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

[0002] JP 2000-110956A discloses a directional control valve including a valve housing, a main spool bore formed in the valve housing, a spool slidably mounted in the main spool bore, a supply passage communicating with the main spool bore, return passages communicating with a tank and with the main spool bore at both ends of the valve housing, and a pair of actuator passages communicating with the main spool bore between the supply and return passages. In the directional control valve, when the spool is in a neutral position, the pair of actuator passages are disconnected from the supply and return passages. When the spool moves to one side from the neutral position, one actuator passage communicates with the return passage and the other actuator passage communicates with the supply passage, thereby operating the actuator. When the spool moves to the other side from the neutral position, the other actuator passage communicates with the return passage and the one actuator passage communicates with the supply passage, thereby operating the actuator in the reverse direction. In this way, the directional control valve has three positions.

[0003] Here, dozers and the like are sometimes equipped with a float function that levels the ground using the weight of the blade. The float function is achieved by connecting each of a pair of actuator passages to a tank. To add a float function to the three-position directional control valve described in JP 2000-110956 A, it is necessary to change the valve to a four-position valve by adding a position in which each of the pair of actuator passages is connected to a tank. In this case, the configuration of the passages in the valve housing must be changed, and a valve housing dedicated to the four-position valve must be manufactured, which increases manufacturing costs.

[0004] An object of the present invention is to easily manufacture a four-position control valve having a float function.

[0005] According to one aspect of the present invention, there is provided a control valve for controlling the flow of working fluid supplied from a hydraulic pressure pump to an actuator, the control valve comprising: a spool movable in an axial direction; and a valve body having an accommodation hole in which the spool is slidably accommodated, the valve body having first and second supply ports that open to the accommodation hole and through which working fluid discharged from the hydraulic pressure pump is guided, a first tank port that opens in the accommodation hole to the outside of the first supply port, a second tank port that opens in the accommodation hole to the outside of the second supply port, a first actuator port that opens in the accommodation hole between the first supply port and the first tank port and communicates with the actuator, and a second actuator port that opens in the accommodation hole between the second supply port and the second tank port and communicates with the actuator, the control valve having a valve body that is configured such that the first actuator port is blocked from the first supply port and the first tank port, and the second actuator port is blocked from the second supply port and the second tank port. a first switching position, where the spool is moved in one direction from the neutral position and the first actuator port is communicated with the first supply port and the second actuator port is communicated with the second tank port; a second switching position, where the spool is moved in the other direction from the neutral position and the first actuator port is communicated with the first tank port and the second actuator port is communicated with the second supply port; and a third switching position, where the spool is moved further from the second switching position and the first actuator port is communicated with the first tank port and the second actuator port is communicated with the second tank port. The spool has a discharge groove that can communicate between the second actuator port and the second tank port as the spool moves at the third switching position, and a spacer having an insertion hole through which the spool is inserted is attached to the discharge groove side of the valve body.

[0006] Fig. 1 is a cross-sectional view of a control valve according to an embodiment of the present invention, showing a state in which the main spool is in a neutral position. Fig. 2 is a cross-sectional view of a control valve according to an embodiment of the present invention, showing a state in which the main spool is in a first switching position. Fig. 3 is a cross-sectional view of a control valve according to an embodiment of the present invention, showing a state in which the main spool is in a second switching position. Fig. 4 is a cross-sectional view of a control valve according to an embodiment of the present invention, showing a state in which the main spool is in a third switching position.

[0007] A control valve according to an embodiment of the present invention will be described with reference to the drawings. The control valve is mounted on a work machine such as a construction machine, industrial machine, or agricultural machine equipped with a traveling device. In this embodiment, a control valve 100 mounted on a hydraulic excavator as the work machine will be described as an example. The control valve 100 is used to drive an actuator of the hydraulic excavator. An example in which hydraulic oil is used as a working fluid to drive the actuator will be described, but other fluids such as hydraulic water may also be used as the working fluid.

[0008] Although not shown, the hydraulic excavator includes a traveling unit, a dozer device attached to the traveling unit, a swivel unit rotatably attached to an upper portion of the traveling unit, and an excavation unit attached to the swivel unit. The traveling unit has crawlers, and the crawlers are driven by a travel motor to cause 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. The dozer device includes a blade that can come into contact with the ground and a blade cylinder 111 (see FIG. 1 ) that serves as an actuator for raising and lowering the blade. In this embodiment, the control valve 100 is used to control the operation of the blade cylinder 111.

[0009] 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 control valve 100 that controls the flow of hydraulic oil supplied from the pump 110 to a blade cylinder 111, and a tank 119 to which the hydraulic oil is returned from the control valve 100.

[0010] The control valve 100 will be described in detail with reference to Fig. 1. As shown in Fig. 1, the control valve 100 includes a main spool 170 as a spool that is movable in the axial direction, a sub-spool 180 that moves in a direction perpendicular to the axial direction of the main spool 170, and a valve body 10 in which the main spool 170 and the sub-spool 180 are slidably housed.

[0011] First, the valve body 10 will be described in detail.

[0012] The valve body 10 has a main accommodating hole 150 as an accommodating hole in which a main spool 170 is slidably accommodated, and a sub accommodating hole 160 in which a sub spool 180 is slidably accommodated. The structure of the valve body 10 is substantially symmetrical.

[0013] The valve body 10 has a pump port 121 that opens into the main accommodating hole 150 and communicates with the pump 110, first and second supply ports 124a, 124b that open into the main accommodating hole 150 and through which hydraulic oil discharged from the pump 110 is guided through the pump port 121, a first tank port 128a that opens to the outside of the first supply port 124a in the main accommodating hole 150, a second tank port 128b that opens to the outside of the second supply port 124b in the main accommodating hole 150, a first actuator port 125a that opens between the pump port 121 and the first tank port 128a in the main accommodating hole 150 and communicates with the blade cylinder 111, and a second actuator port 125b that opens between the pump port 121 and the second tank port 128b in the main accommodating hole 150 and communicates with the blade cylinder 111. In the main accommodating hole 150, from right to left in FIG. 1, a first tank port 128a, a first actuator port 125a, a first supply port 124a, a pump port 121, a second supply port 124b, a second actuator port 125b, and a second tank port 128b open in this order.

[0014] The valve body 10 also has a first actuator passage 126a that connects the first actuator port 125a and the anti-rod side chamber 111a of the blade cylinder 111, a second actuator passage 126b that connects the second actuator port 125b and the rod side chamber 111b of the blade cylinder 111, a tank passage 129 that connects the tank 119 with the first tank port 128a and the second tank port 128b, a first supply passage 123a that connects the sub-accommodating hole 160 and the first supply port 124a, and a second supply passage 123b that connects the sub-accommodating hole 160 and the second supply port 124b.

[0015] The first and second actuator passages 126a, 126b open to the outer peripheral surface of the valve body 10 and communicate via piping (not shown) with the anti-rod side chamber 111a and the rod side chamber 111b, respectively, of the blade cylinder 111. The tank passage 129 is formed in a U-shape in the cross section shown in Figure 1, and the first and second tank ports 128a, 128b open near both axial ends of the main accommodating hole 150.

[0016] The sub-accommodating bore 160 and the first and second supply passages 123a, 123b form a so-called bridge passage. When hydraulic oil is introduced to the lower end side of the sub-spool 180 and becomes highly pressurized, the sub-spool 180 opens, connecting the sub-accommodating bore 160 to the first and second supply passages 123a, 123b. This allows hydraulic oil to be introduced into the first and second supply passages 123a, 123b.

[0017] A first spacer 20a having an insertion hole 21a through which the main spool 170 is inserted, and a second spacer 20b having an insertion hole 21b through which the main spool 170 is inserted are respectively attached to the valve body 10. The first and second spacers 20a, 20b have the same shape and are respectively attached symmetrically to opposing outer peripheral surfaces of the valve body 10 so that the insertion holes 21a, 21b communicate with the main accommodating hole 150. The following describes the second spacer 20b, and for the first spacer 20a, components identical to those of the second spacer 20b are illustrated with the suffix a, and description thereof will be omitted.

[0018] The second spacer 20b has an annular main body portion 22b that is provided in contact with the valve body 10, and a spigot portion 23b that is formed with a smaller diameter than the main body portion 22b and is fitted into the valve body 10. In this embodiment, the insertion hole 21b is formed coaxially with the main accommodating bore 150 and has an inner diameter slightly larger than that of the main accommodating bore 150. The second spacer 20b is attached to the valve body 10 by fitting the spigot portion 23b into a mounting recess 15b that is formed on the outer peripheral surface of the valve body 10 and has a diameter larger than that of the main accommodating bore 150. This makes it easy to ensure concentricity of the insertion hole 21b with the main accommodating bore 150 of the valve body 10. The functions of the first and second spacers 20a, 20b will be described later.

[0019] The control valve 100 also includes a first pilot cap 130a having a first pilot chamber 131a to which pilot pressure acting on one end of the main spool 170 is introduced, and a second pilot cap 130b having a second pilot chamber 131b to which pilot pressure acting on the other end of the main spool 170 is introduced. The first and second pilot caps 130a, 130b have similar shapes and are attached to the valve body 10 with bolts or the like. That is, the first and second pilot caps 130a, 130b are symmetrically attached to the valve body 10 via spacers 20a, 20b, respectively. The following describes the second pilot cap 130b, and for the first pilot cap 130a, the same components as those in the second pilot cap 130b are illustrated with the suffix "a" added to the reference numerals, and description thereof will be omitted.

[0020] The second pilot cap 130b has a pilot port 135b that introduces pilot pressure from the outside to the second pilot chamber 131b. The second pilot chamber 131b is provided with a spring 132b that axially biases the main spool 170, a position determining portion 133b that determines the stroke end position of the main spool 170, and a seat 134b that is provided between the spring 132b and the main spool 170. The spring 132b is provided in a compressed state between the position determining portion 133b and the seat 134b, and biases the main spool 170 to a neutral position (described below). The position determining portion 133b is provided on the pilot port 135b side of the second pilot chamber 131b, and comes into contact with the main spool 170 when the main spool 170 moves to the stroke end. A communication passage 136b that connects the pilot port 135b and the second pilot chamber 131b is formed in the position determining portion 133b, and pilot pressure is introduced from the outside to the second pilot chamber 131b through the pilot port 135b and the communication passage 136b.

[0021] The control valve 100 is a four-position control valve. Specifically, the control valve 100 has a neutral position (the state shown in FIG. 1 ) in which no pilot pressure is applied to the first and second pilot chambers 131 a, 131 b, a first switching position (the state shown in FIG. 2 ) in which pilot pressure is introduced to the first pilot chamber 131 a and the main spool 170 is shifted from the neutral position to one side (the left side in FIG. 1 ), a second switching position (the state shown in FIG. 3 ) in which pilot pressure is introduced to the second pilot chamber 131 b and the main spool 170 is shifted from the neutral position to the other side (the right side in FIG. 1 ), and a third switching position (the state shown in FIG. 4 ) in which an even larger pilot pressure is introduced to the second pilot chamber 131 b and the main spool 170 is shifted further from the second switching position.

[0022] The blade cylinder 111 is driven by hydraulic oil being supplied to the anti-rod side chamber 111a or the rod side chamber 111b through the first and second actuator passages 126a, 126b depending on the position of the main spool 170. The operation of the control valve 100 and the flow of hydraulic oil will be described later.

[0023] Next, the main spool 170 will be described in detail.

[0024] The main spool 170 has a plurality of cylindrical lands with a uniform outer diameter that slide against the inner circumferential surface of the main housing bore 150. Specifically, the main spool 170 has a supply-side land 171 located near the axial center of the main spool 170, first and second outlet-side lands 172a, 172b located on the left and right sides of the supply-side land 171, respectively, and first and second tank-side lands 173a, 173b located outside the first and second outlet-side lands 172a, 172b, respectively. The second tank-side land 173b corresponds to the "land" in the claims. The main spool 170 is provided with the first tank-side land 173a, the first outlet-side land 172a, the supply-side land 171, the second outlet-side land 172b, and the second tank-side land 173b arranged in this order from right to left in FIG. 1 .

[0025] The supply-side land portion 171 can, with its outer peripheral surface, block communication between the pump port 121 and the sub-accommodating hole 160. The first outlet-side land portion 172a can, with its outer peripheral surface, block communication between the first supply port 124a and the first actuator port 125a, and the second outlet-side land portion 172b can, with its outer peripheral surface, block communication between the second supply port 124b and the second actuator port 125b. The first tank-side land portion 173a can, with its outer peripheral surface, block communication between the first actuator port 125a and the first tank port 128a, and the second tank-side land portion 173b can, with its outer peripheral surface, block communication between the second actuator port 125b and the second tank port 128b. The first and second tank-side lands 173a, 173b are exposed from the main accommodating hole 150, and portions thereof slide into the main accommodating hole 150.

[0026] A first small diameter portion 174a, which is formed continuously with the first tank side land portion 173a and has a smaller diameter than the first tank side land portion 173a, is formed at the end of the main spool 170 on the first pilot cap 130a side, and a second small diameter portion 174b, which is formed continuously with the second tank side land portion 173b and has a smaller diameter than the second tank side land portion 173b, is formed at the end of the main spool 170 on the second pilot cap 130b side. The first and second small diameter portions 174a, 174b contact the position determining portions 133a, 133b, respectively, to determine the stroke ends of the main spool 170.

[0027] An annular groove is provided between each land portion. A first annular groove 175 is provided between the supply-side land portion 171 and the first discharge-side land portion 172a, and a second annular groove 176 is provided between the supply-side land portion 171 and the second discharge-side land portion 172b. A third annular groove 177 is provided between the first discharge-side land portion 172a and the first tank-side land portion 173a, and a fourth annular groove 178 is provided between the second discharge-side land portion 172b and the second tank-side land portion 173b.

[0028] The main spool 170 has a notch 193 as a discharge groove formed in the second tank side land portion 173b.

[0029] The notches 193 are provided on the outer peripheral surface of the second tank land portion 173b, extending in the axial direction of the main spool 170 and spaced equally apart circumferentially. In this embodiment, four notches 193 are provided on the outer peripheral surface of the second tank land portion 173b. As shown in FIG. 1 , when the main spool 170 is in the neutral position, the notches 193 communicate with the second tank port 128b but do not communicate with the adjacent second actuator port 125b. Furthermore, when the main spool 170 is stroked to the left in FIG. 1 and is in the first exchange position (see FIG. 2 ), the notches 193 do not communicate with the second pilot chamber 131b of the second pilot cap 130b, and a portion of the notches 193 is located within the insertion hole 21b of the second spacer 20b. Note that the number of notches 193 is not limited to the above, and only one notch may be provided. Alternatively, the notches 193 may be replaced by an annular groove formed around the entire outer peripheral surface of the main spool 170.

[0030] Next, the operation of the control valve 100 according to this embodiment will be described with reference to FIGS.

[0031] When the operator of the hydraulic excavator operates a blade operation lever (not shown) provided in the driver's seat of the hydraulic excavator to raise and lower the blade, for example, during ground leveling, a pilot pressure is output as an operation command to the first pilot chamber 131a or the second pilot chamber 131b of the control valve 100. This causes the main spool 170 to stroke, and hydraulic oil is supplied to the anti-rod-side chamber 111a or the rod-side chamber 111b of the blade cylinder 111, causing the blade cylinder 111 to expand and contract, and raising and lowering the blade.

[0032] When the blade operating lever is held in the neutral position, the main spool 170 is held in the neutral position, as shown in FIG. 1 . With the main spool 170 in the neutral position, the outer peripheral surface of the supply-side land portion 171 blocks communication between the pump port 121 and the sub-accommodation hole 160. The outer peripheral surface of the first tank-side land portion 173a blocks communication between the first actuator port 125a and the first tank port 128a, and the outer peripheral surface of the second tank-side land portion 173b blocks communication between the second actuator port 125b and the second tank port 128b. The outer peripheral surface of the first outlet-side land portion 172a blocks communication between the first supply port 124a and the first actuator port 125a, and the outer peripheral surface of the second outlet-side land portion 172b blocks communication between the second supply port 124b and the second actuator port 125b. In other words, when the main spool 170 is in the neutral position, the anti-rod side chamber 111 a and the rod side chamber 111 b are not in communication with either the pump 110 or the tank 119 .

[0033] When the blade operating lever is operated to raise the blade, pilot pressure is introduced into the first pilot chamber 131a. As a result, the main spool 170 strokes to the left in Figure 2, reaching the first switching position shown in Figure 2. Figure 2 shows a state in which the main spool 170 has reached the end of its stroke, with the second small diameter portion 174b contacting the position determining portion 133b of the second pilot cap 130b. In the first switching position, the pump port 121 and the sub-accommodating hole 160 communicate with each other through the first annular groove 175, and hydraulic oil from the pump port 121 is introduced into the sub-accommodating hole 160.

[0034] When hydraulic oil is introduced into the sub-accommodating bore 160, the pressure in the sub-accommodating bore 160 opens the sub-spool 180, and hydraulic oil is introduced from the sub-accommodating bore 160 to the first and second supply passages 123a, 123b. When the main spool 170 is in the first switching position, the first supply port 124a and the first actuator port 125a are in communication with each other through the third annular groove 177. Therefore, the hydraulic oil introduced into the first supply passage 123a is introduced into the first actuator passage 126a through the first supply port 124a, the third annular groove 177, and the first actuator port 125a. The hydraulic oil introduced into the first actuator passage 126a is supplied to the anti-rod-side chamber 111a.

[0035] Furthermore, when the main spool 170 is in the first switching position, the second actuator port 125b and the second tank port 128b communicate with each other through the fourth annular groove 178. Therefore, hydraulic oil is discharged from the rod side chamber 111b of the blade cylinder 111 to the tank passage 129 through the second actuator passage 126b, the second actuator port 125b, the fourth annular groove 178, and the second tank port 128b. This causes the blade cylinder 111 to extend and the blade to rise. Therefore, when ground leveling with the blade is not being performed, the hydraulic excavator can be traveled without the blade coming into contact with the ground.

[0036] Furthermore, when the blade operating lever is operated to lower the blade, pilot pressure is directed to the second pilot chamber 131b. This causes the main spool 170 to move to the right in FIG. 3 , reaching the second switching position shown in FIG. 3 . In the second switching position, the main spool 170 does not reach the end of its stroke, and a gap is formed between the first small diameter portion 174a of the main spool 170 and the position determining portion 133a of the first pilot cap 130a. In this state, the pump port 121 and the sub-accommodating bore 160 communicate with each other through the second annular groove 176, and hydraulic oil from the pump port 121 is directed to the sub-accommodating bore 160. The sub-spool 180 then opens, directing hydraulic oil from the sub-accommodating bore 160 to the first and second supply passages 123a and 123b. When the main spool 170 is in the second switching position, the second supply port 124b and the second actuator port 125b communicate with each other through the fourth annular groove 178. Therefore, the hydraulic oil guided to the second supply passage 123b is guided to the second actuator passage 126b through the second supply port 124b, the fourth annular groove 178, and the second actuator port 125b. The hydraulic oil guided to the second actuator passage 126b is supplied to the rod-side chamber 111b of the blade cylinder 111.

[0037] Furthermore, when the main spool 170 is in the second switching position, the first actuator port 125a and the first tank port 128a are in communication with each other through the third annular groove 177. Therefore, hydraulic oil is discharged from the rod side chamber 111b of the blade cylinder 111 to the tank 119 through the second actuator passage 126b, the second actuator port 125b, the fourth annular groove 178, the second tank port 128b, and the tank passage 129. This causes the blade cylinder 111 to contract and the blade to descend. Therefore, the pressure of the hydraulic oil lowers the blade, allowing the blade to be pressed against the ground and perform ground leveling.

[0038] In this embodiment, the control valve 100 is also equipped with a float function that uses the blade's own weight to level the ground. When the blade operating lever is operated to enable the float function, a pilot pressure greater than that in the second switching position is introduced into the second pilot chamber 131b. This causes the main spool 170 to move further rightward in FIG. 4 from the second switching position to the third switching position shown in FIG. 4. In the third switching position, the main spool 170 reaches its stroke end, and the first small diameter portion 174a contacts the position determining portion 133a of the first pilot cap 130a. In this state, communication between the pump port 121 and the sub-accommodation bore 160 is blocked, and communication between the first supply port 124a and the first actuator port 125a and between the second supply port 124b and the second actuator port 125b is blocked. In other words, when the main spool 170 is in the third switching position, the anti-rod side chamber 111 a and the rod side chamber 111 b do not communicate with the pump 110 .

[0039] On the other hand, when the main spool 170 is in the third switching position, the first actuator port 125a and the first tank port 128a communicate with each other through the third annular groove 177 of the main spool 170. Furthermore, because the notch 193 communicates with not only the second tank port 128b but also the second actuator port 125b, the second actuator port 125b and the second tank port 128b communicate with each other through the notch 193 of the main spool 170. Therefore, the rod-side chamber 111b communicates with the tank 119 through the second actuator passage 126b, the second actuator port 125b, the notch 193, the second tank port 128b, and the tank passage 129. Furthermore, the anti-rod-side chamber 111a of the blade cylinder 111 communicates with the tank 119 through the first actuator passage 126a, the first actuator port 125a, the third annular groove 177, the first tank port 128a, and the tank passage 129. As a result, the anti-rod side chamber 111a and the rod side chamber 111b communicate with the tank 119, become tank pressure, and the blade cylinder 111 contracts due to the blade's own weight. This provides a float function, allowing the blade to rise and fall along the shape of the ground, and allows the blade to level the ground by following the shape of the ground.

[0040] As described above, the control valve 100 of this embodiment is a four-position control valve that, in addition to the neutral position, first switching position, and second switching position of a three-position control valve, adds a third switching position in which both the anti-rod side chamber 111a and the rod side chamber 111b of the blade cylinder 111 communicate with the tank 119 by forming a notch 193 in the main spool 170. In other words, by changing the configuration of the three-position control valve to one in which the main spool 170 has a notch 193, it is possible to add the third switching position used for the float function without changing the configuration of the passage on the valve body 10 side from the three-position one, thereby achieving a four-position control valve 100. In other words, with the control valve 100 of this embodiment, there is no need to prepare a valve body 10 dedicated to the four-position, and the four-position valve body 10 can be used in common with the three-position valve body 10.

[0041] Furthermore, by attaching the second spacer 20b to the valve body 10, the main spool 170 can be made longer by the axial length of the second spacer 20b. Specifically, by attaching the second spacer 20b to the second tank side land portion 173b side of the valve body 10, the second tank side land portion 173b can be made longer than the 3-position type by the axial length of the second spacer 20b, and the area (axial length) in which the notch 193 is formed can be secured.

[0042] In this way, by modifying the main spool 170 and attaching the second spacer 20b to the valve body 10, the four-position valve body 10 can be made common with the three-position valve body 10, and therefore the four-position control valve 100 with a float function can be easily manufactured.

[0043] Furthermore, in the control valve 100 of this embodiment, a first spacer 20a is attached to the first tank-side land portion 173a side of the valve body 10, and a first pilot cap 130a is attached to the first spacer 20a with bolts or the like. That is, like the second pilot cap 130b, the first pilot cap 130a is not attached to the valve body 10 directly with bolts or the like, but is attached to the valve body 10 via the first spacer 20a. Therefore, by attaching the first spacer 20a in addition to the second spacer 20b to the valve body 10, the first pilot cap 130a and the second pilot cap 130b can be attached to the valve body 10 using a common attachment structure.

[0044] Furthermore, in the control valve 100 of this embodiment, as shown in FIG. 4, when the main spool 170 is in the third switching position, the outer end 173d of the second tank land 173b is located within the second spacer 20b. In other words, even when the main spool 170 is at its maximum stroke to the right in FIG. 1-4, the second tank land 173b does not come off the second spacer 20b. This prevents the outer end 173d from getting caught on the opening end 24b of the insertion hole 21b of the second spacer 20b when the main spool 170 moves. Furthermore, the first tank land 173a of the main spool 170 is formed longer than that of the third-position control valve. Therefore, as shown in FIG. 2, even when the main spool 170 is in the first switching position, the outer end 173c of the first tank land 173a is located within the first spacer 20a. 1-4, the first tank land portion 173a does not come off the first spacer 20a, and therefore, when the main spool 170 moves, the outer end portion 173c is prevented from getting caught on the opening end 24a of the insertion hole 21a of the first spacer 20a.

[0045] Furthermore, in the control valve 100 of this embodiment, the inner diameter of the insertion hole 21b of the second spacer 20b is larger than the inner diameter of the main accommodating hole 150 of the valve body 10. This prevents the outer end 173d of the second tank side land portion 173b from getting caught on the inner circumferential surface of the insertion hole 21b of the second spacer 20b when the main spool 170 moves. Similarly, for the first spacer 20a, the outer end 173c of the first tank side land portion 173a is prevented from getting caught on the inner circumferential surface of the insertion hole 21a of the first spacer 20a.

[0046] Furthermore, in the control valve 100 of this embodiment, the second tank-side land portion 173b is longer than that of a three-position main spool, and a second spacer 20b is provided between the second pilot cap 130b and the valve body 10 to accommodate this. This eliminates the need to lengthen the second pilot cap 130b axially, eliminating the need for a dedicated second pilot cap for the four-position valve. Furthermore, in the control valve 100, the first tank-side land portion 173a is longer than that of a three-position main spool by the amount of the first spacer 20a provided between the first pilot cap 130a and the valve body 10. Therefore, by adjusting the length of the first tank-side land portion 173a without changing the first pilot cap 130a from that for the three-position valve, the first small diameter portion 174a of the main spool 170 can be brought into contact with the position determining portion 133a of the first pilot cap 130a to determine the stroke end of the main spool 170 (i.e., the third switching position). This eliminates the need for a dedicated first pilot cap for the four-position valve. Therefore, the pilot caps 130a and 130b can be used in common with the three-position caps.

[0047] According to the above-described embodiment, the following advantageous effects are achieved.

[0048] In the control valve 100, when the main spool 170 strokes further from the second switching position, the first actuator port 125a and the first tank port 128a communicate with each other, and the second actuator port 125b and the second tank port 128b communicate with each other through the notch 193. In other words, by providing the notch 193 in the main spool 170, it is possible to change the passage configuration on the valve body 10 side from a three-position version to a four-position version without changing it. Furthermore, by attaching the second spacer 20b to the valve body 10, it is possible to make the main spool 170 longer than the three-position version and ensure an area in which the notch 193 is formed. In this way, by modifying the main spool 170 and attaching the second spacer 20b to the valve body 10, the four-position valve body 10 can be made common to the three-position valve body 10, and therefore the four-position control valve 100 with a float function can be easily manufactured.

[0049] 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.

[0050] <Modification 1> In the above embodiment, first and second spacers 20a, 20b are attached to the valve body 10. The first spacer 20a allows the pilot caps 130a, 130b to be attached to the valve body 10 in a common structure, and also allows the stroke end (third switching position) of the main spool 170 to be determined without changing the first pilot cap 130a from a three-position type. However, the first spacer 20a is not essential when there is no need to commonize the attachment structure of the pilot caps 130a, 130b to the valve body 10, or when the stroke end of the main spool 170 is determined by, for example, lengthening the first pilot cap 130a in the axial direction.

[0051] <Modification 2> In the above embodiment, the control valve 100 includes the first pilot cap 130a including the first pilot chamber 131a and the second pilot cap 130b including the second pilot chamber 131b. However, instead of the configuration in which the main spool 170 is moved by the pilot pressure, the main spool 170 may be moved, for example, by operating a link mechanism provided at the end of the main spool 170. In that case, the first and second pilot caps 130a, 130b are not essential components of the control valve 100.

[0052] <Modification 3> In the above embodiment, when the main spool 170 is in the third switching position, the outer end 173d of the second tank land portion 173b is located within the second spacer 20b. However, this configuration is not essential if there is no risk of the outer end 173d getting caught on the opening end 24b (see FIG. 4 ) of the insertion hole 21b of the second spacer 20b as the main spool 170 moves. Also, in the above embodiment, the inner diameter of the insertion hole 21b of the second spacer 20b is larger than the inner diameter of the main accommodating bore 150 of the valve body 10. However, this configuration is not essential if there is no risk of the outer end 173d getting caught on the inner circumferential surface of the insertion hole 21b as the main spool 170 moves. In other words, the inner diameter of the insertion hole 21b of the second spacer 20b may be the same as the inner diameter of the main accommodating bore 150 of the valve body 10, and the main spool 170 may slide along the inner circumferential surface of the insertion hole 21b.

[0053] <Modification 4> In the above embodiment, the spacers 20a, 20b have main body portions 22a, 22b that are provided in contact with the valve body 10, and spigot portions 23a, 23b that are formed with a smaller diameter than the main body portions 22a, 22b and are fitted into the valve body 10. However, as long as coaxiality between the insertion holes 21a, 21b of the spacers 20a, 20b and the main accommodating hole 150 of the valve body 10 can be ensured, the spacers 20a, 20b may be attached to the valve body 10 without having the spigot portions 23a, 23b.

[0054] The configuration, operation, and effects of the embodiment of the present invention configured as above will be described below.

[0055] The control valve 100 controls the flow of working fluid supplied from a hydraulic pressure pump 110 to a blade cylinder 111 as an actuator. The control valve 100 includes a main spool 170 as a spool that is movable in the axial direction, and a valve body 10 having a main accommodation hole 150 as an accommodation hole in which the main spool 170 is slidably accommodated. The valve body 10 has first and second supply ports 124 a, 124 b, 124 c, 124 d, 124 e, 124 f, 124 f, 124 g, 124 h, 124 i, 124 m, 124 m, 124 m, 124 m, 124 m, 124 b, 124 c, 124 m ...124b, a first tank port 128a that opens to the outside of the first supply port 124a in the main accommodating hole 150, a second tank port 128b that opens to the outside of the second supply port 124b in the main accommodating hole 150, a first actuator port 125a that opens between the first supply port 124a and the first tank port 128a in the main accommodating hole 150 and communicates with the blade cylinder 111, and a first actuator port 125b that opens between the second supply port 124b and the second tank port 128b in the main accommodating hole 150 and a second actuator port 125b communicating with the blade cylinder 111. The control valve 100 has a neutral position where the first actuator port 125a is blocked from the first supply port 124a and the first tank port 128a, and the second actuator port 125b is blocked from the second supply port 124b and the second tank port 128b, and a position where the main spool 170 is stroked to one side from the neutral position, where the first supply port 124a and the first actuator port 125a are communicated with each other and a first switching position where the second actuator port 125b and the second tank port 128b communicate with each other; a second switching position where the main spool 170 is moved from the neutral position to the other side and the first actuator port 125a and the first tank port 128a communicate with each other and the second actuator port 125b and the second supply port 124b communicate with each other; and a second switching position where the main spool 170 is moved further from the second switching position and the first actuator port 125a and the first tank port 128a communicate with each other. and a third switching position where the second actuator port 125b and the second tank port 128b are in communication with each other, and a fourth switching position where the second actuator port 125b and the second tank port 128b are in communication with each other, and the main spool 170 has a notch 193 that, in the third switching position, allows communication between the second actuator port 125b and the second tank port 128b as the main spool 170 moves, and a second spacer 20b is attached to the notch 193 side of the valve body 10 as a spacer having an insertion hole 21b through which the main spool 170 is inserted.

[0056] In this configuration, when the main spool 170 strokes further from the second switching position, the first actuator port 125a and the first tank port 128a communicate with each other, and the second actuator port 125b and the second tank port 128b communicate with each other through the notch 193. In other words, by providing the notch 193 in the main spool 170, it is possible to change the passage configuration on the valve body 10 side from a three-position version to a four-position version without changing it. Furthermore, by attaching the second spacer 20b to the valve body 10 on the side of the notch 193, the main spool 170 can be made longer than the three-position version, ensuring an area in which the notch 193 can be formed. In this way, by modifying the main spool 170 and attaching the second spacer 20b to the valve body 10, the four-position valve body 10 can be made common to the three-position valve body 10, thereby facilitating the manufacture of a four-position control valve 100 with a float function.

[0057] In the control valve 100, the main spool 170 has a second tank side land portion 173b as a land portion with a uniform outer diameter, a portion of which slides into the main accommodating hole 150 of the valve body 10 and forms a notch 193, and when the main spool 170 is in the third switching position, the outer end portion 173d of the second tank side land portion 173b is located within the second spacer 20b.

[0058] With this configuration, when the main spool 170 slides, the outer end 173d of the second tank side land portion 173b is prevented from getting caught on the opening end 24b of the insertion hole 21b of the second spacer 20b.

[0059] In the control valve 100 , the inner diameter of the insertion hole 21 b of the second spacer 20 b is larger than the inner diameter of the main accommodating hole 150 of the valve body 10 .

[0060] With this configuration, when the main spool 170 slides, the outer end 173d of the second tank side land portion 173b is prevented from getting caught on the inner peripheral surface of the insertion hole 21b of the second spacer 20b.

[0061] In the control valve 100, the second spacer 20b has a main body portion 22b that is provided in contact with the valve body 10, and a spigot portion 23b that is formed with a smaller diameter than the main body portion 22b and is fitted into the valve body 10.

[0062] In this configuration, it is easy to ensure the coaxiality of the insertion hole 21b of the second spacer 20b with respect to the main accommodating hole 150 of the valve body 10.

[0063] The control valve 100 further includes a second pilot cap 130b as a pilot cap having a pilot chamber 131b to which the pilot pressure acting on the main spool 170 is guided, and the second pilot cap 130b is attached to the valve body 10 via a second spacer 20b.

[0064] In this configuration, the second pilot cap 130b can be used in common with the three-position cap.

[0065] 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.

[0066] This application claims priority based on Japanese Patent Application No. 2023-140834, filed with the Japan Patent Office on August 31, 2023, the entire contents of which are incorporated herein by reference.

Claims

1. A control valve for controlling the flow of working fluid supplied from a fluid pressure pump to an actuator, comprising: a spool movable in an axial direction; and a valve body having an accommodation hole in which the spool is slidably accommodated, wherein the valve body has: first and second supply ports opening into the accommodation hole and through which working fluid discharged from the fluid pressure pump is guided; a first tank port opening in the accommodation hole to the outside of the first supply port; a second tank port opening in the accommodation hole to the outside of the second supply port; a first actuator port opening in the accommodation hole between the first supply port and the first tank port and communicating with the actuator; and a second actuator port opening in the accommodation hole between the second supply port and the second tank port and communicating with the actuator, wherein the control valve has a neutral position in which the first actuator port is blocked from the first supply port and the first tank port, and the second actuator port is blocked from the second supply port and the second tank port, and a first switching position, where the spool is stroked in one direction from the neutral position, and where the first actuator port is communicated with the first supply port and the second actuator port is communicated with the second tank port; a second switching position, where the spool is stroked in the other direction from the neutral position, and where the first actuator port is communicated with the first tank port and the second actuator port is communicated with the second supply port; and a third switching position, where the spool is further stroked from the second switching position, and where the first actuator port is communicated with the first tank port and the second actuator port is communicated with the second tank port; the spool has a discharge groove that can communicate between the second actuator port and the second tank port as the spool moves in the third switching position, and a spacer having an insertion hole through which the spool is inserted is attached to the discharge groove side of the valve body.

2. A control valve as claimed in claim 1, wherein the spool has a land portion of a uniform outer diameter, part of which slides in the accommodating hole of the valve body and through which the discharge groove is formed, and when the spool is in the third switching position, the outer end of the land portion is located within the spacer.

3. A control valve as claimed in claim 1, wherein the inner diameter of the insertion hole of the spacer is larger than the inner diameter of the accommodation hole of the valve body.

4. A control valve as claimed in claim 1, wherein the spacer has a main body portion provided in contact with the valve body, and a spigot portion formed with a smaller diameter than the main body portion and fitted into the valve body.

5. A control valve as claimed in claim 1, further comprising a pilot cap having a pilot chamber to which pilot pressure acting on said spool is introduced, said pilot cap being attached to said valve body via said spacer.

Images