JP4564425B2 - Control valve - Google Patents

Description

The present invention includes a sliding spool that is slidably accommodated in a spool chamber of a valve housing, and an oil chamber that slides the sliding spool by applying hydraulic pressure to one end surface in the sliding direction of the sliding spool. It includes, about the configuration and the control valve so as to position the sliding spool stroke end.

Conventionally, for example, Patent Document 1 discloses a control valve.
The one shown in Patent Document 1, (corresponding to spool chamber) spool slide hole 43 of the valve housing 42, a spool 49 (corresponding to the sliding spool), the external command pressure chamber 47 (the oil chamber for sliding operation of the spool The end surface 49H of the spool 49 comes into contact with the lid 46 (corresponding to the stopper), and the spool 49 is positioned at the initial position (corresponding to the stroke end). The spool 49 is positioned at the initial position when the flat end surface 49H of the spool 49 and the flat surface of the lid 46 come into contact with each other.

JP 2000-352401 A (paragraphs [0094]-[0116], FIG. 6-8)

  In this type of control valve, the hydraulic pressure supplied to the oil chamber acts on one end face of the spool, and the spool is slid from the stroke end positioned by the stopper toward the other stroke end. It is. For this reason, when the conventional control valve is used, when the spool receives the hydraulic pressure supplied to the oil chamber and starts to slide from the stroke end, the spool is separated from the stopper and the spool end surface that has been in contact with the stopper until then is removed. Therefore, the pressure receiving area of the spool increases. For this reason, the pressure receiving area of the spool with the spool positioned at the stroke end is different from the pressure receiving area of the spool after the spool slides from the stroke end, and even if hydraulic pressure is supplied to the oil chamber If the hydraulic pressure has not yet increased to a predetermined pressure, a situation in which a sufficient spool operating force is not generated and the spool is difficult to start is likely to occur. Also, when hydraulic pressure that has risen to a predetermined pressure from the beginning of supply is supplied to the oil chamber, a situation in which the spool slides rapidly due to the strong operating force acting on the spool as the spool moves away from the stopper. It was.

  An object of the present invention is to provide a control valve that allows a spool to start and slide smoothly even when there is a change in the hydraulic pressure supplied to the oil chamber.

In the first invention, the sliding spool is slidably accommodated in the spool chamber of the valve housing, and the sliding spool is slid by applying hydraulic pressure to one end face in the sliding direction of the sliding spool. In a control valve comprising an oil chamber to be operated and configured to position the sliding spool at a stroke end,
Forming the one end surface of the sliding spool into a flat surface;
The oil chamber is configured so that the sliding spool fits inside, and a spherical body having an outer diameter substantially the same as the outer diameter of the sliding spool is formed on the one end surface of the sliding spool in the oil chamber. In a position facing the inner wall of the oil chamber in a rotatable manner with respect to the wall surface of the oil chamber,
The sliding spool is positioned at a stroke end by the sphere when the one end surface of the sliding spool comes into contact with the sphere,
When the hydraulic pressure acts on the one end surface of the sliding spool, the sliding spool is moved away from the stroke end by being operated to be separated from the spherical body .

That is, the flat surfaces abutting the spherical sliding spool, because those sliding spool is positioned in the stroke end, the sliding spool and spheres transgression point contact or in a state where the sliding spool is positioned in the stroke end The pressure receiving area of the sliding spool when the sliding spool is in the state close to point contact and the sliding spool is located at the stroke end is the same as or approximately the pressure receiving area of the sliding spool when the sliding spool is separated from the sphere. Can be the same.

Therefore, according to the first aspect of the present invention, even if there is a slight change in the hydraulic pressure, such as the hydraulic pressure supplied to the oil chamber is a predetermined pressure or a lower pressure, the sliding spool is separated from the stroke end and the sphere . Regardless of the position, slide the slide spool smoothly so that it does not easily change the speed so that the oil pressure is applied to the pressure receiving area of the same or almost the same area and the sliding spool is started with good response. Control by the control valve can be performed smoothly with good responsiveness.

Further , since the oil pressure in the oil chamber pressurizes the flat surface of the sliding spool, when the sliding spool is operated to slide, the operating force for operating the sliding spool in a direction inclined with respect to the sliding direction. There while allowing less likely to occur, can be as sliding spool and the sphere is in contact.

Therefore, according to the first invention, the pressure receiving area of the spool when the sliding spool is positioned at the stroke end and the pressure receiving area of the spool when the sliding spool is separated from the stopper are the same or substantially the same. Although the sliding spool and the sphere can be brought into contact with each other, the switching operation can be smoothly performed so that the sliding spool to be slid is not easily twisted.

Further, the sphere is rotated in the oil chamber such as for hydraulic, while hardly site in contact with the sliding spool sphere is changed to generate abrasion of a sphere, it can be as sliding spool and the sphere is in contact .
Therefore, according to the first invention, the pressure receiving area of the spool when the sliding spool is located at the stroke end and the pressure receiving area of the spool when the sliding spool is separated from the sphere are the same or substantially the same. While the sliding spool can be brought into contact with the sphere, the sphere can be obtained in a highly durable state so that the sphere is hardly worn.

According to the second aspect of the present invention, in the configuration of the first aspect of the invention, the one end surface of the sliding spool is positioned with respect to the center of the sphere, with the opening facing the oil chamber of the port that supplies hydraulic pressure to the oil chamber. It is biased to the side.

Embodiments of the present invention will be described below with reference to the drawings.
As shown in FIG. 1, a self-propelled body 3 having a pair of left and right crawler type traveling devices 1 and a dozer device 2 is provided with a swivel base 6 having a driving unit 4 and a driving unit 5 so as to be capable of swiveling. A backhoe device 8 is connected to the front end of the swivel base 6 via a bracket 7 to form a backhoe with a dozer.

  As shown in FIG. 2, the output shaft 21a of the turning hydraulic motor 21 is linked to the turning operation shaft 11 of the turning operation mechanism 10 (see FIG. 3) for turning the turntable 6 via the planetary gear reduction mechanism 20. A hydraulic pump 25 is connected to the input port of the swing control valve 23 connected to the swing hydraulic motor 21 via a pair of hydraulic circuits 22, 22 via an oil supply path 24. A pilot hydraulic pump 29 is connected via a pilot oil supply passage 28 to an input port of a turning operation device 27 in which a pilot control valve (not shown) is connected to the pilot operation portion 23 a via a pilot operation oil passage 26. is there.

  A negative brake 30 is configured to act on the turning hydraulic motor 21, and an input port of the negative brake 30 is connected to an output port of the turning operation device 27 via a brake oil passage 31.

  When the pressure oil is discharged through the brake oil passage 31, the negative brake 30 is braked by the input operation force of the brake spring 32 and brakes on the output shaft 21 a of the swing hydraulic motor 21, whereby the negative brake 30 is applied to the swivel 6. When the brake oil enters the brake state and pressure oil is supplied from the brake oil passage 31, the release action is performed for pressurization by the pressure oil, and the brake action on the output shaft 21a of the swing hydraulic motor 21 is released. By this, it will be in a cutting state so that the braking action with respect to the turntable 6 may be cancelled | released.

  The swing hydraulic motor 21 is constituted by an axial plunger type hydraulic motor whose capacity can be changed by changing the swash plate angle. As shown in FIG. 2, the swing hydraulic motor 21 is provided with a speed change hydraulic cylinder 41. The operation mechanism 40 is linked.

  As shown in FIG. 2, the speed change operation mechanism 40 has an output port connected to the speed change hydraulic cylinder 41 linked to the capacity change operation portion 21 b of the swing hydraulic motor 21 via the speed change oil path 42. A speed control valve 43, a high pressure selection valve 45 having an output port connected to an input port of the speed control valve 43 via a delivery oil passage 44, and a control valve switching mechanism 46 linked to the speed control valve 43. Configured.

  As shown in FIG. 3, the transmission hydraulic cylinder 41 is constituted by a single-acting hydraulic cylinder in which a piston 41 a is linked to a swash plate as a capacity changing operation portion 21 b of the swing hydraulic motor 21. The shift hydraulic cylinder 41 is urged toward the side of switching the swing hydraulic motor 21 to the small capacity state by a return force provided so that the capacity changing operation portion 21b of the swing hydraulic motor 21 automatically returns to the small capacity position H. As a result, the transmission hydraulic cylinder 41 is supplied with pressure oil from the speed control valve 43 and pressurized to a pressure higher than the set pressure determined by the urging force by the capacity changing operation portion 21b of the swing hydraulic motor 21, thereby increasing the capacity. When operated, the capacity changing operation portion 21b of the swing hydraulic motor 21 is switched to the large capacity position L to switch the swing hydraulic motor 21 to the large capacity state. The speed change hydraulic cylinder 41 is discharged to the small capacity side by discharging the pressure oil by the speed control valve 43, and the capacity changing operation portion 21b of the swing hydraulic motor 21 is switched to the small capacity position H by its return force. By operating, the swing hydraulic motor 21 is switched to the small capacity state.

  The speed control valve 43 can be switched between an oil supply state ON and an oil discharge state OF. When the speed control valve 43 is switched to the oil supply state ON, the hydraulic pressure from the high pressure selection valve 45 is transferred to the speed change hydraulic cylinder 41 via the speed change oil passage 42. When the oil is supplied and switched to the oil discharge state OF, the oil is discharged from the speed change hydraulic cylinder 41 via the speed change oil passage 42, and the waste oil flows into the oil discharge passage 47. The drain oil passage 48 is further joined to the drain oil passage 49 of the swing hydraulic motor 21.

  A pair of input portions of the high pressure selection valve 45 are communicated with the pair of hydraulic circuits 22 and 22 that drive the swing hydraulic motor 21 via the introduction oil passages 50 and 51, respectively. The hydraulic circuit 22 having a higher pressure is selected from the pair of hydraulic circuits 22 to drive the swing hydraulic motor 21, the hydraulic pressure is taken out from the high-pressure side hydraulic circuit 22, and this hydraulic pressure is sent via the delivery oil path 44. To the speed control valve 43.

  The control valve switching mechanism 46 includes an oil supply side pilot oil passage 46 a connected to one pilot operation portion 43 a of the speed control valve 43 and an oil supply side pilot oil connected to the other pilot operation portion 43 b of the speed control valve 43. And a path 46b. The oil supply side pilot oil passage 46b takes out the pilot oil pressure from the high pressure selection valve 45 from the delivery oil passage 44 and supplies it to the pilot operation portion 43b on the side where the speed control valve 43 is switched to the oil supply state ON. The oil drain side pilot oil passage 46a takes out the pilot oil pressure from the brake oil passage 31, and supplies it to the pilot operation portion 43a on the side where the speed control valve 43 is switched to the oil discharge state OF.

  That is, when the driving load of the swing hydraulic motor 21 becomes large, high-pressure pilot hydraulic pressure is supplied to the pilot operating portion 43b of the speed control valve 43 by the oil supply side pyro oil passage 46b, and the pilot oil pressure from the oil supply side pilot oil passage 46b By making the control valve switching operation force generated in the speed control valve 43 larger than the control valve switching operation force generated in the speed control valve 43 by the pilot oil pressure from the drain side pilot oil passage 46a, the control valve switching mechanism 46, the speed control valve 43 is switched to the oil supply state ON by the difference in the control valve switching operation force. On the other hand, when the driving load of the swing hydraulic motor 21 becomes small, a small pilot oil pressure is supplied to the pilot operating portion 43b of the speed control valve 43 by the oil supply side pyro oil passage 46b, and the oil pressure from the oil supply side pilot oil passage 46b. The control valve switching operation force generated in the speed control valve 43 by the pilot hydraulic pressure is made smaller than the control valve switching operation force generated in the speed control valve 43 by the pilot hydraulic pressure from the oil drain side pilot oil passage 46a. The valve switching mechanism 46 switches the speed control valve 43 to the oil discharge state OF by the difference in the control valve switching operation force.

  That is, when the turning lever 27a provided to the turning operation device 27 so as to be swingable is operated to the left turning position LE or the right turning position RI, the turning operation device 27 uses the pilot hydraulic pressure from the pilot hydraulic motor 29 as a pilot. Supplying to the pilot operating portion 23a of the turning control valve 23 via the operation oil passage 26, the turning control valve 23 is operated to switch to the left turn side or right turn side drive state corresponding to the operation position of the turn lever 27a, The swing control valve 23 supplies the hydraulic pressure from the hydraulic pump 25 to the swing hydraulic motor 21 via one hydraulic circuit 22, and the swing control valve 23 discharges the pressure oil discharged from the swing motor 21 to the other hydraulic circuit 22. Discharge into the oil passage 52. At this time, the turning operation device 27 supplies the pilot hydraulic pressure from the pilot hydraulic motor 29 to the negative brake 30 via the brake oil passage 31, and the negative brake 30 is turned off to release the braking action on the turntable 6. Yes. Thereby, the turning hydraulic motor 21 is driven in the turning direction corresponding to the operation position of the turning lever 27a to drive the turning operation shaft 11 of the turning operation mechanism 10 via the speed reduction mechanism 20, and the turntable 6 is moved to the turning lever 27a. It is driven to turn leftward or rightward corresponding to the operation position.

  When the turning lever 27a of the turning operation device 27 is operated to the neutral position N, the turning operation device 27 drains oil from any pilot operation portion 23a of the turning control valve 23 via the pilot oil passage 26, and the turning control valve 23 The pressure oil supply to the swing hydraulic motor 21 is stopped in the neutral state. Thereby, the turning hydraulic motor 21 stops and the turning stand 6 stops. At this time, the turning operation device 27 drains oil from the negative brake 30 via the brake oil passage 31, and the negative brake 30 enters the engaged state, and the turntable 6 is braked.

  When the swivel base 6 is driven to the left turn side or the right turn side, the high pressure selection valve 45 extracts the hydraulic pressure from the hydraulic circuit 22 on the high pressure side for driving the swing hydraulic motor 21 to control the speed. Supply to valve 43. Further, the control valve switching mechanism 46 supplies the pilot hydraulic pressure from the high pressure selection valve 45 to the pilot operating portion 43b of the speed control valve 43 through the oil supply side pilot oil passage 46b, and the pilot from the brake oil passage 31 through the oil discharge side pilot oil passage 46a. The hydraulic pressure is supplied to the pilot operating portion 43a of the speed control valve 43, respectively.

  For this reason, the drive load of the swing hydraulic motor 21 is small, such as the bucket 8a (see FIG. 1) of the backhoe device 8 is lifted from the ground and is not subjected to the movement resistance due to the soil, so that the swivel 6 is swiveled. In some cases, the circuit pressure generated in the hydraulic circuit 22 becomes low, and the pilot hydraulic pressure supplied to the speed control valve 43 by the oil supply side pilot oil passage 46b becomes low, so that the speed control valve 43 enters the oil discharge state OF. When the switching hydraulic cylinder 41 is drained, the swing hydraulic motor 21 is switched to a small capacity state, the swing hydraulic motor 21 is driven at high speed, and the swivel base 6 can be driven to rotate at high speed.

  On the other hand, a circuit generated in the hydraulic circuit 22 when the driving load of the swing hydraulic motor 21 is large, for example, when the swivel 6 is swiveled to level the ground while the bucket 8a of the backhoe device 8 is used as a dozer means. Since the pressure becomes high and the pilot hydraulic pressure supplied to the speed control valve 43 through the oil supply side pilot oil passage 46b becomes high, the speed control valve 43 is switched to the oil supply state ON, and the speed change hydraulic cylinder 41 is oiled. Then, the swing hydraulic motor 21 is automatically switched to a state where the swing hydraulic motor 21 is driven at a low speed by switching the swing hydraulic motor 21 to a large capacity state, and the swivel base 6 can be driven to swing with high torque.

  The relief pressure of the relief valve 53 when the circuit pressure of the hydraulic circuit 22 on the high pressure side from which the hydraulic pressure is taken out by the high pressure selection valve 45 begins to wipe off the relief valve 53 (see FIG. 3) provided in the hydraulic circuit 22, and the relief valve The speed control valve 43 is configured so that the swing hydraulic motor 21 is switched from the small capacity state to the large capacity state when the pressure is between the relief pressure of the relief valve 53 when the 53 is fully opened. It is. Thus, the swing hydraulic motor 21 can be switched between the small capacity state and the large capacity state while suppressing the occurrence of a shift shock as much as possible.

  As shown in FIG. 3, the turning operation mechanism 10 includes a turning race 12 supported by a self-propelled machine body 3, and the turning operation shaft 11 having a gear portion 11 a meshed with the turning race 12 is connected to a turntable. 6 is configured to be rotatably supported by a speed reduction case 13 fixed to 6.

  As shown in FIG. 3, the negative brake 30 has a brake disk 33 supported on a cylinder block 21 c of the swing hydraulic motor 21 so as to be integrally rotatable, and a brake piston 34 and a brake piston 34 in the motor case of the swing hydraulic motor 21. The brake spring 32 is provided.

  That is, when the pressure oil is discharged from the brake piston 34 to the brake oil passage 31, the brake spring 32 presses the brake disc 34 against the motor case portion 35 via the brake piston 34, whereby the negative brake 30 is Then, it enters a state in which a friction brake is applied to the output shaft 21a of the swing hydraulic motor 21. When pressure oil is supplied to the brake piston 34 from the brake oil passage 31, the brake piston 34 is pressurized to compress the brake spring 32, and the brake spring 32 presses against the motor case portion 35 of the brake disc 33. To release. As a result, the negative brake 30 is turned off so as to release the braking applied to the output shaft 21 a of the swing hydraulic motor 21.

  As shown in FIG. 3, the speed control valve 43 and the high pressure selection valve 45 are mounted on the motor case of the swing hydraulic motor 21. The pair of relief valves 53 (see FIG. 2) of the hydraulic circuit 22 are disposed on the opposite side of the high pressure selection valve 45 and the speed control valve 43 with respect to the motor body including the cylinder block 21c of the swing hydraulic motor 21. It is attached to the motor case. Ports A, B, and M provided in the motor case of the swing hydraulic motor 21 as shown in FIG. 3 correspond to the ports A, B, and M shown in FIG.

  The speed control valve 43 will be described in further detail. As shown in FIG. 4, the speed control valve 43 is provided in a valve housing 60 formed of a motor case (see FIG. 3) of the swing hydraulic motor 21, and provided in the valve housing 60. A sliding spool 62 accommodated in a spool chamber 61 formed of a through hole, a large-diameter oil chamber 63 formed on one end side of the spool chamber 61, a stopper 64 constituted by a sphere accommodated in the large-diameter oil chamber 63, a slide A small-diameter oil chamber 65 formed by a hole drilled in the dynamic spool 62, a switching spring 66 accommodated in the small-diameter oil chamber 65, and a plug piston 67 inserted into the small-diameter oil chamber 65 are provided.

  An input port 71 connected to the valve housing 60 is connected to a pilot port 70 that communicates with the exhaust oil side pilot oil passage 46a, one oil passage that constitutes the delivery oil passage 44 and the oil supply side pilot oil passage 46b. The output port 72 connected to the transmission oil passage 42 and the oil discharge port 73 connected to the oil discharge passage 47 are arranged side by side in the sliding direction of the sliding spool 62.

  As shown in FIG. 4A, the sliding spool 62 abuts the end face 62a of the sliding spool 62 on one end side against the stopper 64, and slides using the plug member 74 screwed to the valve housing 60 as a reaction force member. The large-capacity stroke end positioned by the stopper 64 in a state of supporting the spool 62 and the end face 62b on the other end side of the sliding spool 62 are screwed to the valve housing 60 as shown in FIG. The stopper member 75 is brought into contact with the stopper member 75 and is slidably operated over the small-capacity side stroke end positioned by the stopper member 75.

  FIG. 4 (a) shows a state in which the sliding spool 62 is operated to the large capacity side stroke end, and FIG. 4 (b) shows the sliding spool 62 from one of the large capacity side stroke end and the small capacity side stroke end to the other. FIG. 4 (c) shows a state in which the sliding spool 62 is operated to the small capacity side stroke end. As shown in FIG. 4 (a), when the sliding spool 62 is operated to the large capacity side stroke end, the sliding spool 62 is input by the annular groove 76 provided on the outer peripheral surface side of the sliding spool 62. The port 71 is communicated with the output port 72. As shown in FIG. 4C, when the sliding spool 62 is operated to the small capacity side stroke end, the sliding spool 62 causes the output port 72 to communicate with the oil discharge port 73 by the annular groove 76. .

  The plug piston 67 is slidably fitted into one end of the small-diameter oil chamber 65 of the sliding spool 62 so that the pressure oil does not enter and exit through the opening of the small-diameter oil chamber 65 of the sliding spool 62. It is sealed. The switching spring 66 presses the sliding piston 62 against the sliding piston 62 using the plug piston 67 received and supported by the plug member 75 as a reaction member, thereby slidably biasing the sliding spool 62 toward the large-capacity stroke end. is doing.

The large-diameter oil chamber 63, the stopper 64, and the like constitute the pilot operation portion 43a.
That is, when the sliding spool 62 is operated to the stroke end on the large capacity side, the contact between the one end surface 62a formed on the flat surface of the sliding spool 62 and the projecting spherical surface 64a formed by the spherical outer peripheral surface of the stopper 64. The sliding spool 62 is positioned at the stroke end of the large-capacity side, and a portion other than the portion in contact with the stopper 64 of the one end surface 62a of the sliding spool 62 is opened in the large-diameter oil chamber 63. When pilot oil pressure is supplied from the drain side pilot oil passage 46 a, this pilot oil pressure is introduced into the large-diameter oil chamber 63 through the pilot port 70, and the pilot oil pressure is introduced into the large-diameter oil chamber 63 by one end surface 62 a of the sliding spool 62. The sliding spool 62 is slid from the large-capacity side stroke end toward the small-capacity side stroke end.

The small diameter oil chamber 65, the switching spring 66, and the like constitute the pilot operating portion 43b.
That is, the small-diameter oil chamber 65 has an oil passage 77 formed by through holes provided in the middle of the sliding spool 62 in a distributed manner in the circumferential direction of the sliding spool 62, and an annular shape provided on the outer peripheral surface side of the sliding spool 62. When the pilot oil pressure is supplied from the oil supply side pilot oil passage 46 b, the pilot oil pressure is supplied from the input port 71 through the annular groove 78 and the oil passage 77 to communicate with the input port 71 through the groove 78. The pilot oil pressure is applied to the small-diameter oil chamber wall surface 62c of the sliding spool 62 by the small-diameter oil chamber 65, and the sliding spool 62 is moved from the small-capacity side stroke end by the operating force of the pilot oil pressure and the switching spring 66. Sliding to the large capacity side slot.

  The hydraulic pressure supplied from the high pressure selection valve 45 through the delivery oil passage 44 is introduced from the input port 71 into the small diameter oil chamber 65 through the annular groove 78 and the oil passage 77.

The one end surface 62a of the sliding spool 62 has a pressure receiving area S1, the pilot hydraulic pressure of the hydraulic pressure BP is supplied by the oil drain side pilot oil passage 46a, and the small-diameter oil indoor wall surface 62c of the sliding spool 62 has a pressure receiving area S2. It is assumed that the switching spring 66 exhibits the switching operation force of the operation force SP, and the pilot oil pressure of the oil pressure MP is supplied by the oil supply side pilot oil passage 46b.
Then, due to the pilot hydraulic pressure BP from the oil drain side pilot oil passage 46a, an operating force FH = S1 × BP for sliding the sliding spool 62 toward the small capacity side stroke end is generated. Due to the pilot oil pressure MP from the oil supply side pilot oil passage 46b and the operating force SP of the switching spring 66, an operating force FL = S2 × MP + SP for sliding the sliding spool 62 toward the stroke end of the large capacity side is generated. . When the operating force FL becomes larger than the operating force FH, the sliding spool 62 is switched to the large-capacity stroke end by the operating force FL, and when the operating force FL becomes smaller than the operating force FH, the sliding force is moved by the operating force FH. The dynamic spool 62 is switched to the small capacity side stroke end.

  That is, when the driving load of the swing hydraulic motor 21 is reduced, the circuit pressure generated in the hydraulic circuit 22 becomes low, so the swing control valve 43 has a large diameter from the brake oil passage 31 through the oil drain side pilot oil passage 46a. The sliding spool 62 is slid to the small capacity side stroke end by the pilot hydraulic pressure supplied to the oil chamber 63 and acting on the one end surface 62a of the sliding spool 62 in the large diameter oil chamber 63, and the output port 72 is slid. The oil pressure state of the transmission hydraulic cylinder 41 is switched from the transmission oil passage 42 to the oil discharge passage 47 through the annular groove 76 of the spool 62, and the transmission hydraulic cylinder 41 turns. The shift hydraulic cylinder 41 is operated to the small capacity side so that the hydraulic motor 21 is switched to the small capacity state.

  On the other hand, when the driving load of the swing hydraulic motor 21 becomes large, the circuit pressure generated in the hydraulic circuit 22 becomes high. Therefore, the swing control valve 43 is connected to the small diameter oil from the hydraulic circuit 22 through the oil supply side pilot oil passage 46b. The sliding spool 62 is slid to the stroke end of the large capacity side by the pilot oil pressure supplied to the chamber 65 and acting on the wall surface 62c of the small-diameter oil chamber of the sliding spool 62 in this small-diameter oil chamber 65. In operation, the input port 71 is switched to the oil supply state ON in which the input port 71 is communicated with the output port 72 by the annular groove 76 of the sliding spool 62, and the hydraulic pressure supplied from the hydraulic circuit 22 by the high pressure selection valve 45 is changed via the transmission oil passage 43. Is supplied to the transmission hydraulic cylinder 41, and the transmission hydraulic cylinder 41 switches the swing hydraulic motor 21 to the large capacity state and operates the transmission oil. The cylinder 41 is operated in a mass side.

[Another Example]
Various hydraulic actuators such as a speed control valve 43 for switching the swing hydraulic motor 21 between a large capacity state and a small capacity state, and a speed control valve for switching the traveling hydraulic motor between a large capacity state and a small capacity state are provided. The present invention can also be applied to various control valves to be operated. Therefore, the speed control valve 43 and the like are collectively referred to as a control valve 43 simply.

Overall side view of backhoe with dozer Hydraulic circuit diagram Sectional view of swivel operation mechanism and hydraulic motor (A) is a cross-sectional view of the speed control valve in the oil supply state, (B) is a cross-sectional view in the middle of switching of the speed control valve, and (C) is a cross-sectional view of the speed control valve in the oil drained state.

60 Valve housing 61 Spool chamber 62 Sliding spool 63 Oil chamber 64 sphere 62a One end surface of sliding spool
70 ports

Claims (2)

A sliding spool slidably accommodated in a spool chamber of the valve housing, and an oil chamber for slidingly operating the sliding spool by applying hydraulic pressure to one end surface in the sliding direction of the sliding spool. A control valve configured to position a dynamic spool at a stroke end,
Forming the one end surface of the sliding spool into a flat surface;
The oil chamber is configured so that the sliding spool fits inside, and a spherical body having an outer diameter substantially the same as the outer diameter of the sliding spool is formed on the one end surface of the sliding spool in the oil chamber. In a position facing the inner wall of the oil chamber in a rotatable manner with respect to the wall surface of the oil chamber,
The sliding spool is positioned at a stroke end by the sphere when the one end surface of the sliding spool comes into contact with the sphere,
A control valve configured such that when a hydraulic pressure acts on the one end face of the sliding spool, the sliding spool is moved away from the stroke end with respect to the spherical body . The control valve according to claim 1 , wherein an opening facing the oil chamber of a port for supplying hydraulic pressure to the oil chamber is biased toward a side where the one end surface of the sliding spool is located with respect to the center of the sphere .

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