Control valve

Abstract

To easily manufacture a four-position control valve having a float function.SOLUTION: A control valve 100 has four positions of a neutral position, a first switching position, a second switching position, and a third switching position in which a main spool 170 is further stroked from the second switching position and a first actuator port 125a is connected to a first tank port 128a and a second actuator port 125b is connected to a second tank port 128b. The main spool 170 has a notch 193 that can connect the second actuator port 125b to the second tank port 128b as the main spool 170 moves in the third switching position. A second spacer 20b having an insertion hole 21b through which the main spool 170 is inserted is attached to the notch 193 side of a valve body 10.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Patent Document 1 discloses a directional control valve including a valve housing, a main spool hole formed in the valve housing, a spool slidably assembled in the main spool hole, a supply passage communicating with the main spool hole, a return passage communicating with a tank and communicating with the main spool hole at both ends of the valve housing, and a pair of actuator passages communicating with the main spool hole between the supply passage and the return passage. When the spool is in the neutral position, the pair of actuator passages are blocked from the supply passage and the return passage, and 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, and the actuator is actuated. When the spool moves to the other side from the neutral position, the other actuator passage communicates with the return passage and one actuator passage communicates with the supply passage, and the actuator is actuated in the reverse direction. In this way, the directional control valve has three positions. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2000-110956 A Summary of the Invention [Problem to be solved by the invention]

[0004] Here, a dozer or the like may be equipped with a float function that levels the ground by the weight of the blade. The float function is realized by connecting each of a pair of actuator passages to a tank. When adding a float function to the three-position directional control valve described in Patent Document 1, it is necessary to change the valve to a four-position valve by adding a position where each of the pair of actuator passages is connected to a tank. In that case, since the configuration of the passages in the valve housing must be changed, it is necessary to manufacture a valve housing dedicated to the four positions, which increases the manufacturing cost.

[0005] The present invention has been made in consideration of the above problems, and has an object to easily manufacture a four-position control valve having a float function. [Means for solving the problem]

[0006] The present invention provides a control valve for controlling a flow of a working fluid supplied from a fluid 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 has first and second supply ports that open to the accommodation hole and through which working fluid discharged from the fluid pressure pump is guided, a first tank port that opens to the outside of the first supply port in the accommodation hole, a second tank port that opens to the outside of the second supply port in the accommodation hole, a first actuator port that opens to the accommodation hole between the first supply port and the first tank port and communicates with an actuator, and a second actuator port that opens to the accommodation hole between the second supply port and the second tank port and communicates with the actuator. The control valve is configured to be in a neutral state 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. a first switching position, which is a position where the spool has stroked in one direction from the neutral position and in which 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, which is a position where the spool has stroked in the other direction from the neutral position and in which 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, which is a position where the spool has stroked further from the second switching position and in which 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, and a spacer having an insertion hole through which the spool is inserted is attached to the discharge groove side of the valve body.

[0007] In this invention, when the spool strokes further from the second switching position, the first actuator port and the first tank port communicate with each other, and the second actuator port and the second tank port communicate with each other through the discharge groove. In other words, since the spool has a discharge groove, the passage configuration on the valve body side can be made into a four-position valve without changing it from the three-position valve. Also, since a spacer is attached to the discharge groove side of the valve body, the spool can be made longer than the three-position valve to ensure an area in which the discharge groove is formed. In this way, by changing the spool and attaching a spacer to the valve body, the four-position valve body can be made common to the three-position valve body, and therefore a four-position control valve with a float function can be easily manufactured.

[0008] The present invention is characterized in that the spool has a land portion of a uniform outer diameter, part of which slides into the accommodating hole of the valve body and forms a discharge groove, and when the spool is in the third switching position, the outer end of the land portion is located within the spacer.

[0009] In this invention, the outer end of the land portion is prevented from getting caught on the open end of the insertion hole of the spacer when the spool slides.

[0010] The present invention is characterized in that the inner diameter of the insertion hole of the spacer is larger than the inner diameter of the accommodation hole of the valve body.

[0011] In this invention, the outer end of the land portion is prevented from getting caught on the inner peripheral surface of the insertion hole of the spacer when the spool slides.

[0012] The present invention is characterized in that 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.

[0013] In this invention, it is easy to ensure the concentricity of the insertion hole of the spacer with the accommodation hole of the valve body.

[0014] The present invention is characterized in that it further comprises a pilot cap having a pilot chamber to which pilot pressure acting on the spool is introduced, and the pilot cap is attached to the valve body via a spacer.

[0015] In this invention, the pilot cap can be made common to both the three-position cap and the three-position cap. Effect of the Invention

[0016] According to the present invention, a four-position control valve having a float function can be easily manufactured. [Brief description of the drawings]

[0017] [Figure 1] FIG. 2 is a cross-sectional view showing the control valve according to the embodiment of the present invention, illustrating a state in which the main spool is in a neutral position. [Diagram 2] FIG. 2 is a cross-sectional view of the control valve according to the embodiment of the present invention, showing a state in which the main spool is in a first shift position. [Diagram 3] FIG. 2 is a cross-sectional view showing the control valve according to the embodiment of the present invention, illustrating a state in which the main spool is in a second switching position. [Figure 4] FIG. 2 is a cross-sectional view showing the control valve according to the embodiment of the present invention, illustrating a state in which the main spool is in a third switching position. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] 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 be used as the working fluid.

[0019] Although not shown, the hydraulic excavator includes a traveling section, a dozer device provided on the traveling section, a rotating section rotatably provided on the upper part of the traveling section, and an excavation section provided on the rotating section. The traveling section has crawlers, and the hydraulic excavator travels when the crawlers are driven by a traveling motor. The excavation section includes a boom rotatably attached to the rotating section, 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) as an actuator that raises and lowers the blade. In this embodiment, the control valve 100 is used to control the operation of the blade cylinder 111.

[0020] The hydraulic excavator is equipped with 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 returns from the control valve 100.

[0021] 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.

[0022] First, the valve body 10 will be described in detail.

[0023] 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 approximately symmetrical.

[0024] 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.

[0025] The valve body 10 also has a first actuator passage 126a connecting the first actuator port 125a and the anti-rod side chamber 111a of the blade cylinder 111, a second actuator passage 126b connecting the second actuator port 125b and the rod side chamber 111b of the blade cylinder 111, a tank passage 129 connecting the tank 119 with the first tank port 128a and the second tank port 128b, a first supply passage 123a connecting the sub-accommodating hole 160 and the first supply port 124a, and a second supply passage 123b connecting the sub-accommodating hole 160 and the second supply port 124b.

[0026] The first and second actuator passages 126a, 126b open to the outer circumferential surface of the valve body 10 and communicate with the anti-rod side chamber 111a and the rod side chamber 111b of the blade cylinder 111 through piping (not shown), respectively. The tank passage 129 is formed in a U-shape in the cross-sectional view shown in Figure 1, and the first and second tank ports 128a, 128b open near both axial ends of the main accommodating hole 150, respectively.

[0027] The sub-accommodating hole 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, and the sub-accommodating hole 160 communicates with the first and second supply passages 123a, 123b. This allows hydraulic oil to be introduced to the first and second supply passages 123a, 123b.

[0028] 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 symmetrically attached to opposing outer circumferential surfaces of the valve body 10 so that the insertion holes 21a, 21b communicate with the main accommodating hole 150. Below, the second spacer 20b will be described, and for the first spacer 20a, the same components as those of the second spacer 20b will be illustrated with the suffix "a" added to the reference numerals, and description thereof will be omitted.

[0029] The second spacer 20b has an annular main body portion 22b provided in contact with the valve body 10, and a spigot portion 23b formed with a smaller diameter than the main body portion 22b and fitted into the valve body 10. In this embodiment, the insertion hole 21b is formed coaxially with the main accommodating hole 150, and has an inner diameter slightly larger than the inner diameter of the main accommodating hole 150. The second spacer 20b is attached to the valve body 10 by fitting the spigot portion 23b into a mounting recess 15b formed on the outer circumferential surface of the valve body 10 with a larger diameter than the main accommodating hole 150. This makes it easy to ensure the concentricity of the insertion hole 21b with respect to the main accommodating hole 150 of the valve body 10. The functions of the first and second spacers 20a and 20b will be described later.

[0030] The control valve 100 also includes a first pilot cap 130a having a first pilot chamber 131a to which the 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 the pilot pressure acting on the other end of the main spool 170 is introduced. The first and second pilot caps 130a, 130b have the same shape, and are attached to the valve body 10 by 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. Below, the second pilot cap 130b will be described, and for the first pilot cap 130a, the same components as those of the second pilot cap 130b will be illustrated with the suffix "a" to the reference numerals, and description thereof will be omitted.

[0031] 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 urges the main spool 170 in the axial direction, a position determining portion 133b that determines the position of the stroke end of the main spool 170, and a seating portion 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 seating portion 134b, and urges the main spool 170 to a neutral position described later. 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 communicates between 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 through the pilot port 135b and the communication passage 136b to the second pilot chamber 131b.

[0032] The control valve 100 is a four-position control valve. Specifically, the control valve 100 has a neutral position (state shown in FIG. 1) where no pilot pressure acts on the first and second pilot chambers 131a and 131b, a first switching position (state shown in FIG. 2) where pilot pressure is introduced to the first pilot chamber 131a and the main spool 170 is stroked from the neutral position to one side (the left side in FIG. 1), a second switching position (state shown in FIG. 3) where pilot pressure is introduced to the second pilot chamber 131b and the main spool 170 is stroked from the neutral position to the other side (the right side in FIG. 1), and a third switching position (state shown in FIG. 4) where an even larger pilot pressure is introduced to the second pilot chamber 131b and the main spool 170 is stroked further from the second switching position.

[0033] The blade cylinder 111 is driven by supplying hydraulic oil 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.

[0034] Next, the main spool 170 will be described in detail.

[0035] The main spool 170 has a plurality of cylindrical lands having a uniform outer diameter that slide against the inner circumferential surface of the main housing hole 150. Specifically, the main spool 170 has a supply side land 171 provided near the center of the main spool 170 in the axial direction, first and second outlet side land portions 172a, 172b provided on the left and right sides of the supply side land portion 171, respectively, and first and second tank side land portions 173a, 173b provided outside the first and second outlet side land portions 172a, 172b, respectively. The second tank side land portion 173b corresponds to the "land portion" in the claims. The main spool 170 has the first tank side land portion 173a, the first outlet side land portion 172a, the supply side land portion 171, the second outlet side land portion 172b, and the second tank side land portion 173b arranged in this order from the right side to the left side in FIG. 1.

[0036] The supply side land portion 171 can block communication between the pump port 121 and the sub-accommodating hole 160 by the outer circumferential surface. The first discharge side land portion 172a can block communication between the first supply port 124a and the first actuator port 125a by the outer circumferential surface, and the second discharge side land portion 172b can block communication between the second supply port 124b and the second actuator port 125b by the outer circumferential surface. The first tank side land portion 173a can block communication between the first actuator port 125a and the first tank port 128a by the outer circumferential surface, and the second tank side land portion 173b can block communication between the second actuator port 125b and the second tank port 128b by the outer circumferential surface. The first and second tank side land portions 173a and 173b are exposed from the main accommodating hole 150 and slide partially into the main accommodating hole 150.

[0037] A first small diameter portion 174a is formed continuously with the first tank side land portion 173a and has a smaller diameter than the first tank side land portion 173a at the end of the main spool 170 on the first pilot cap 130a side, and a second small diameter portion 174b is formed continuously with the second tank side land portion 173b and has a smaller diameter than the second tank side land portion 173b 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.

[0038] An annular groove is provided between each of the lands. A first annular groove 175 is provided between the supply side land 171 and the first outlet side land 172a, and a second annular groove 176 is provided between the supply side land 171 and the second outlet side land 172b. A third annular groove 177 is provided between the first outlet side land 172a and the first tank side land 173a, and a fourth annular groove 178 is provided between the second outlet side land 172b and the second tank side land 173b.

[0039] The main spool 170 has a notch 193 as a discharge groove formed in the second tank side land portion 173b.

[0040] The notches 193 are provided on the outer peripheral surface of the second tank side land portion 173b, and extend in the axial direction of the main spool 170 and are provided at equal intervals in the circumferential direction. In this embodiment, four notches 193 are provided on the outer peripheral surface of the second tank side 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 and do not communicate with the adjacent second actuator port 125b. 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 are partly located within the insertion hole 21b of the second spacer 20b. The number of notches 193 is not limited to the above, and only one may be provided. Instead of the notches 193, an annular groove formed over the entire outer peripheral surface of the main spool 170 may be used.

[0041] Next, the operation of the control valve 100 according to this embodiment will be described with reference to FIGS.

[0042] When an operator of a hydraulic excavator operates a blade operation lever (not shown) provided at the driver's seat of the hydraulic excavator to raise and lower the blade, for example, when leveling land, 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 the blade to rise and fall.

[0043] 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. When the main spool 170 is in the neutral position, the outer circumferential surface of the supply side land portion 171 blocks communication between the pump port 121 and the sub-accommodation hole 160. The outer circumferential 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 circumferential 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 circumferential surface of the first discharge side land portion 172a blocks communication between the first supply port 124a and the first actuator port 125a, and the outer circumferential surface of the second discharge 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 .

[0044] When the blade operating lever is operated so as to raise the blade, pilot pressure is introduced to the first pilot chamber 131a. As a result, the main spool 170 strokes to the left in FIG. 2, and reaches the first switching position shown in FIG. 2. FIG. 2 shows a state in which the main spool 170 has stroked to the stroke end and the second small diameter portion 174b has come into contact with 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 the hydraulic oil from the pump port 121 is introduced to the sub-accommodating hole 160.

[0045] When hydraulic oil is introduced into the sub-accommodating hole 160, the sub-spool 180 opens due to the pressure in the sub-accommodating hole 160, and hydraulic oil is introduced from the sub-accommodating hole 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 communicate 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.

[0046] Furthermore, when the main spool 170 is in the first shift 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 is not being performed with the blade, the hydraulic excavator can be traveled without the blade coming into contact with the ground.

[0047] Also, when the blade operating lever is operated so that the blade descends, pilot pressure is introduced to the second pilot chamber 131b. As a result, the main spool 170 strokes to the right in FIG. 3, and is in the second switching position shown in FIG. 3. In the second switching position, the main spool 170 does not stroke to the stroke end, 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 hole 160 communicate with each other through the second annular groove 176, and the hydraulic oil from the pump port 121 is introduced to the sub-accommodating hole 160. Then, the sub-spool 180 opens, and the hydraulic oil is introduced from the sub-accommodating hole 160 to the first and second supply passages 123a and 123b. In a state in which 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.

[0048] Furthermore, when the main spool 170 is in the second switching position, the first actuator port 125a and the first tank port 128a communicate 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 blade is lowered by the pressure of the hydraulic oil, and the blade can be pressed against the ground to perform ground leveling.

[0049] In this embodiment, the control valve 100 is equipped with a float function that uses the weight of the blade to level the ground. When the blade operating lever is operated to perform the float function, a pilot pressure greater than that in the second switching position is introduced into the second pilot chamber 131b. As a result, the main spool 170 strokes further to the right 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 strokes to the stroke end, and the first small diameter portion 174a contacts the position determining portion 133a of the first pilot cap 130a. In this state, the communication between the pump port 121 and the sub-accommodation hole 160 is blocked, and the communication between the first supply port 124a and the first actuator port 125a, and the communication between the second supply port 124b and the second actuator port 125b are 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 .

[0050] 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. In addition, since 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. In addition, the counter 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 and are at tank pressure, and the blade cylinder 111 is contracted by the weight of the blade. This exerts 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.

[0051] Thus, the control valve 100 of the present embodiment is a four-position control valve in which a third switching position is added 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 addition to the neutral position, the first switching position, and the second switching position of the three-position control valve. In other words, by changing the configuration of the three-position control valve to a configuration in which the main spool 170 has the notch 193, it is possible to add a 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, and a four-position control valve 100 can be obtained. In other words, with the control valve 100 of the present embodiment, it is not necessary 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.

[0052] 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 by the axial length of the second spacer 20b than that of the 3-position type, and the area (axial length) in which the notch 193 is formed can be secured.

[0053] 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 the four-position control valve 100 with a float function can be easily manufactured.

[0054] Furthermore, in the control valve 100 of this embodiment, the first spacer 20a is attached to the first tank side land portion 173a side of the valve body 10, and the 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 directly to the valve body 10 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 attachment structure of the first pilot cap 130a and the second pilot cap 130b to the valve body 10 can be made common.

[0055] 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 side land portion 173b is located inside the second spacer 20b. That is, even when the main spool 170 is at the maximum stroke to the right in FIG. 1-4, the second tank side land portion 173b does not come off the second spacer 20b. This prevents the outer end portion 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. In addition, the first tank side land portion 173a of the main spool 170 is formed longer than that of the third position, and as shown in FIG. 2, even when the main spool 170 is in the first switching position, the outer end portion 173c of the first tank side land portion 173a is located inside the first spacer 20a. That is, even when the main spool 170 is at its maximum stroke to the left in FIG. 1-4, the first tank side land portion 173a does not come off the first spacer 20a. Therefore, when the main spool 170 moves, the outer end portion 173c is prevented from getting caught on the opening end portion 24a of the insertion hole 21a of the first spacer 20a.

[0056] 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 accommodation hole 150 of the valve body 10. This prevents the outer end 173d of the second tank side land portion 173b from being 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 being caught on the inner circumferential surface of the insertion hole 21a of the first spacer 20a.

[0057] In the control valve 100 of this embodiment, the second tank side land portion 173b is made longer than the main spool for three positions, and therefore the second spacer 20b is provided between the second pilot cap 130b and the valve body 10, so that the second pilot cap 130b does not need to be made longer in the axial direction, and therefore there is no need to prepare a second pilot cap exclusively for four positions. Furthermore, in the control valve 100, the first tank side land portion 173a is made longer than the main spool for three positions 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 the one for three positions, 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 (in other words, the third switching position). In other words, there is no need to prepare a first pilot cap exclusively for four positions. Therefore, the pilot caps 130a and 130b can be made common to the three-position caps.

[0058] According to the above-described embodiment, the following advantageous effects are obtained.

[0059] In the control valve 100, when the main spool 170 strokes further from the second switching position, the first actuator port 125a communicates with the first tank port 128a, and the second actuator port 125b communicates with the second tank port 128b through the notch 193. In other words, since the main spool 170 has the notch 193, the passage configuration on the valve body 10 side can be changed from the three-position to a four-position without changing it. Also, since the second spacer 20b is attached to the valve body 10, the main spool 170 can be made longer than the three-position to ensure an area in which the notch 193 is formed. In this way, by changing 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 having a float function can be easily manufactured.

[0060] The following modified examples are also within the scope of the present invention, and it is possible to combine the configurations shown in the modified examples with the configurations described in the above-mentioned embodiments, to combine the configurations described in the different embodiments above, or to combine the configurations described in the different modified examples below.

[0061] <Variation 1> In the above embodiment, the 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 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 elongating the first pilot cap 130a in the axial direction, for example.

[0062] <Variation 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, for example, the main spool 170 may be moved 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.

[0063] <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 side land portion 173b is located inside the second spacer 20b. However, if there is no risk that the outer end 173d will be caught on the opening end 24b (see FIG. 4) of the insertion hole 21b of the second spacer 20b when the main spool 170 moves, the above configuration is not essential. In addition, 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 hole 150 of the valve body 10, but if there is no risk that the outer end 173d will be caught on the inner circumferential surface of the insertion hole 21b when the main spool 170 moves, the above configuration is not essential. In other words, the inner diameter of the insertion hole 21b of the second spacer 20b may be formed to be the same diameter as the inner diameter of the main accommodating hole 150 of the valve body 10, and the main spool 170 may slide on the inner circumferential surface of the insertion hole 21b.

[0064] <Variation 4> In the above embodiment, the spacers 20a, 20b have main body portions 22a, 22b provided in contact with the valve body 10, and spigot portions 23a, 23b formed with a smaller diameter than the main body portions 22a, 22b and fitted into the valve body 10. However, as long as the concentricity of 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.

[0065] The configuration, operation, and effects of the embodiment of the present invention configured as above will be described below.

[0066] The control valve 100 controls the flow of the working fluid supplied from the hydraulic pump 110 to the blade cylinder 111 as an actuator. The control valve 100 includes a main spool 170 as a spool movable in the axial direction, and a valve body 10 having a main accommodating hole 150 as an accommodating hole in which the main spool 170 is slidably accommodated. The valve body 10 has first and second supply ports 124a, 124b, 124c, 124d, 124e, 124f, 124g, 124h, 124h, 124i, 124j ...124b, a first tank port 128a opening to the outside of the first supply port 124a in the main accommodating hole 150, a second tank port 128b opening to the outside of the second supply port 124b in the main accommodating hole 150, a first actuator port 125a opening between the first supply port 124a and the first tank port 128a in the main accommodating hole 150 and communicating with the blade cylinder 111, and a second actuator port 125b opening 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 in which 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 in which the main spool 170 has stroked in one direction from the neutral position, in which 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 communicates with the second tank port 128b; a second switching position where the main spool 170 is stroked from the neutral position to the other side and where the first actuator port 125a communicates with the first tank port 128a and the second actuator port 125b communicates with the second supply port 124b; and a second switching position where the main spool 170 is further stroked from the second switching position and where the first actuator port 125a communicates with the first tank port 128a. and a third switching position in which the second actuator port 125b and the second tank port 128b communicate with each other, and the main spool 170 has a notch 193 that can communicate between the second actuator port 125b and the second tank port 128b as the main spool 170 moves in the third switching position, 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.

[0067] In this configuration, when the main spool 170 strokes further from the second switching position, the first actuator port 125a communicates with the first tank port 128a, and the second actuator port 125b communicates with the second tank port 128b through the notch 193. In other words, since the main spool 170 has the notch 193, the passage configuration on the valve body 10 side can be changed from the three-position to a four-position without changing it. Also, since the second spacer 20b is attached to the notch 193 side of the valve body 10, the main spool 170 can be made longer than the three-position to ensure an area in which the notch 193 is formed. In this way, by changing 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 having a float function can be easily manufactured.

[0068] 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 to form 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 positioned within the second spacer 20b.

[0069] In 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.

[0070] In the control valve 100, 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 .

[0071] In this configuration, when the main spool 170 slides, the outer end portion 173d of the second tank side land portion 173b is prevented from getting caught on the inner circumferential surface of the insertion hole 21b of the second spacer 20b.

[0072] In the control valve 100, the second spacer 20b has a main body portion 22b provided in contact with the valve body 10, and a spigot portion 23b formed with a smaller diameter than the main body portion 22b and fitted into the valve body 10.

[0073] In this configuration, the coaxiality of the insertion hole 21b of the second spacer 20b with the main accommodating hole 150 of the valve body 10 can be easily ensured.

[0074] 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.

[0075] In this configuration, the second pilot cap 130b can be used in common with the three-position cap.

[0076] Although the embodiments of the present invention have been described above, the above-mentioned embodiments merely show 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-mentioned embodiments. [Explanation of symbols]

[0077] 10...valve body, 20b...second spacer (spacer), 21b...insertion hole, 22b...main body, 23b...spigot portion, 100...control valve, 110...fluid pressure pump (pump), 111...blade cylinder (actuator), 119...tank, 124a...first supply port (supply port), 124b...second supply port (supply port), 125a...first actuator port, 125b...second actuator port, 128a...first tank port, 128b...second tank port, 130b...second pilot cap (pilot cap), 131b...second pilot chamber (pilot chamber), 150...main housing hole (housing hole), 170...main spool (spool), 173b...second tank side land portion (land portion), 173d...outer end, 193...third notch (discharge groove)

Claims

1. A control valve for controlling a flow of a hydraulic fluid supplied from a hydraulic pump to an actuator, a spool movable in an axial direction; a valve body having a receiving hole in which the spool is slidably received, The valve body includes: a first supply port and a second supply port which are open to the receiving hole and through which the working fluid discharged from the fluid pressure pump is guided; a first tank port that opens to an outside of the first supply port in the receiving hole; a second tank port that opens to an outside of the second supply port in the receiving hole; a first actuator port that opens in the receiving hole between the first supply port and the first tank port and communicates with the actuator; a second actuator port that opens in the receiving hole between the second supply port and the second tank port and communicates with the actuator, The control valve is a neutral position in which the first actuator port is isolated from the first supply port and the first tank port, and the second actuator port is isolated from the second supply port and the second tank port; a first switching position where the spool is stroked in one direction from the neutral position, and where the first actuator port and the first supply port are communicated with each other and the second actuator port and the second tank port are communicated with each other; a second switching position where the spool is stroked from the neutral position in the other direction, and where the first actuator port communicates with the first tank port and the second actuator port communicates with the second supply port; a third switching position, where the spool is at a further stroke position from the second switching position, and where the first actuator port and the first tank port are communicated with each other and the second actuator port and the second tank port are communicated with each other; the spool has a discharge groove that is capable of communicating between the second actuator port and the second tank port as the spool moves in the third switching position, a spacer having an insertion hole through which the spool is inserted is attached to the valve body on the discharge groove side.

2. 2. The control valve of claim 1, the spool has a land portion having a uniform outer diameter, a portion of which slides in the accommodation hole of the valve body and in which the discharge groove is formed, A control valve as claimed in any one of claims 1 to 5, wherein an outer end of said land portion is located within said spacer when said spool is in said third switching position.

3. 2. The control valve of claim 1, a spacer having a through hole formed in a spacer and an inner diameter thereof larger than an inner diameter of the accommodation hole formed in the valve body;

4. 2. The control valve of claim 1, The spacer is a main body portion provided in contact with the valve body; a spigot portion formed to have a smaller diameter than the main body portion and fitted into the valve body.

5. 2. The control valve of claim 1, A pilot cap having a pilot chamber to which a pilot pressure acting on the spool is introduced is further provided. The control valve, wherein the pilot cap is attached to the valve body via the spacer.

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