Patent Application
20200208746
The present invention relates to a hydraulic valve.
For example, as a hydraulic valve that performs oil supply control with respect to a hydraulic cylinder, there is a hydraulic valve which includes two spools in a valve main body in order to increase a circulation amount of oil, for example. According to the hydraulic valve, since it is possible to supply oil through two ports, it becomes possible to increase an operating speed of the hydraulic cylinder (see, for example, Patent Literature 1).
Patent Literature 1: Japanese Laid-open Utility Model Publication No. H07-022183
Incidentally, in Patent Literature 1, end parts of two spools are housed in a common pressure chamber, and the two spools are moved by supply of a pilot pressure to this pressure chamber. However, an external force such as a fluid force by a flow of oil, or a frictional force with respect to a valve main body is applied to each of the spools. The external force is not necessarily the same in the two spools, and there often is a difference between the two spools. A spool to which a large external force is applied is less likely to be moved compared to a spool to which a small external force is applied. Thus, as described above, when a pilot pressure is simply supplied to the common pressure chamber, the spool to which the small external force is applied moves before the spool to which the large external force is applied. Thus, a gap is kept generated in oil supply control by the two spools, and there is a possibility that activation of the hydraulic cylinder is influenced.
In view of the forgoing situation, the present invention is to provide a hydraulic valve that can accurately perform oil supply control even in a case where two spools are used.
To attain the above object, a hydraulic valve according to the present invention includes:
two spools which are arranged in a valve main body in a state of being individually movable in an axial direction and being in parallel with each other, and individual end parts of which are housed in a common pressure chamber;
a return spring provided in such a manner as to be placed between each of the spools and the valve main body,
a flow of oil with respect to an oil path connected to the valve main body being controlled by movement of the two spools with respect to the valve main body against a spring force of each of the return springs in a case where a pilot pressure is supplied to the pressure chamber; and
a coupling member that is arranged in such a manner as to bridge the two spools and that is pressed in a direction of becoming closer to the spools by the return springs since being placed between each of the spools and the return springs.
According to the present invention, when a difference is generated between moving amounts of two spools due to a difference in an external force, a coupling member is inclined, and a return spring of a spool with a large moving amount is bent more than a return spring of a spool with a small moving amount. Thus, a moment is applied to the coupling member in a direction of recovering the inclination. As a result, the spool with a large moving amount is pushed back or the return spring of the spool with a small moving amount is bent by the coupling member, whereby the moving amounts of the two spools become identical to each other. Hereinafter, the above-described operation is repeatedly performed each time the moving amounts of the two spools become different from each other, and movement of the two spools is advanced without a large difference being generated therebetween. Accordingly, a situation in which a gap is generated in oil supply control by the two spools is prevented, and it becomes possible to accurately perform the oil supply control.
In the following, a preferred embodiment of a hydraulic valve according to the present invention will be described in detail with reference to the accompanied drawings.
The valve base part 10 is a block-shaped member having two reference end surfaces 10a in parallel with each other. In this valve base part 10, two spool holes 11 that are in parallel with each other are provided. The spool holes 11 are through holes both end parts of each of which are opened to the reference end surfaces 10a and which have round cross-sections, and are formed to have the same shape. In each of the spool holes 11, a first drain port 12, a first actuator port 13, a pump port 14, a second actuator port 15, and a second drain port 16 are provided in the order from a left side in the drawing. These ports 12, 13, 14, and 15.16 are formed in such a manner that positions in an axial direction thereof are identical to each other in the spool holes 11. Each of the first drain ports 12, the pump ports 14, and the second drain ports 16 communicate with each other in the two spool holes 11. Each of the first actuator ports 13 and the second actuator ports 15 is independent from each other in the spool holes 11.
A tank 22 is connected to each of the first drain ports 12, and the second drain ports 16 through a drain oil path 21, and a hydraulic pump 24 is connected to the pump ports 14 through a supply oil path 23. A bottom chamber 1a of the hydraulic cylinder 1 is connected to the two first actuator ports 13 through respective bottom oil paths 25a and 25b, and a rod chamber 1b of the hydraulic cylinder 1 is connected to the two second actuator ports 15 through respective rod oil paths 26a and 26b.
Spools 30 having the same shape are respectively arranged in the spool holes 11 in a state of being in parallel with each other. Each of the spools 30 is a columnar part in which a sliding base part 31 and two guide shaft parts 32 are formed integrally and which has a round cross-section shape, and can move in the axial direction individually. The sliding base part 31 has an outer diameter that can fit into the spool holes 11 in the valve base part 10. A length in the axial direction of the sliding base part 31 is configured to be longer than a distance between the reference end surfaces 10a. The guide shaft parts 32 are thin cylindrical parts provided on both end surfaces of the sliding base part 31 and are configured in such a manner that shaft centers thereof become identical to a shaft center of the sliding base part 31.
In each of the spools 30, a first annular groove 33, a second annular groove 34, and a third annular groove 35 are provided in an outer peripheral surface of the sliding base part 31. The first annular groove 33 is to switch the first actuator port 13 and the first drain port 12 between a communicating state and a blocked state. The second annular groove 34 is to switch the pump port 14 between a state of communicating with the first actuator port 13 and a state of communicating with the second actuator port 15. The third annular groove 35 is to switch the second actuator port 15 and the second drain port 16 between a communicating state and a blocked state.
Also, in each of the spools 30, a first communication groove 36 and a second communication groove 37 are provided in the sliding base part 31 between the first annular groove 33 and the second annular groove 34, and a third communication groove 38 and a fourth communication groove 39 are provided in the sliding base part 31 between the second annular groove 34 and the third annular groove 35. Although not clearly illustrated in the drawing, these communication groove 36, 37, 38, and 39 are formed in a plurality of positions at equal intervals along a peripheral surface of the sliding base part 31. The first communication groove 36 is provided in such a manner as to be opened from an outer peripheral surface of the sliding base part 31 to the first annular groove 33, and the second communication groove 37 and the third communication groove 38 are provided in such a manner as to be opened from the outer peripheral surface of the sliding base part 31 to the second annular groove 34. The fourth communication groove 39 is provided in such a manner as to be opened from the outer peripheral surface of the sliding base part 31 to the third annular groove 35.
More specifically, in a case where each of the spools 30 is arranged in a neutral position illustrated in
When each of the spools 30 moves to a left side from the neutral position illustrated in
As illustrated in
At an end part of each of the spools 30, a retainer 44 is arranged, and a coupling member 45 is arranged in such a manner as to bridge the two spools 30. As illustrated in
Moreover, as illustrated in
In the hydraulic valve configured in the above-described manner, each of the spools 30 is kept in the neutral position illustrated in
From this state, for example, as illustrated in
On the one hand, as illustrated in
In such a manner, according to this hydraulic valve, oil circulates to the hydraulic cylinder 1 through the two first actuator ports 13 and the two second actuator ports 15 provided individually. Thus, it is possible to increase a circulation amount of the oil compared to a case where oil circulates through a single port. Thus, it becomes possible to increase an operation speed of the hydraulic cylinder 1, and there is an advantage of being able to make an operation more efficient.
In addition, according to this hydraulic valve, a large difference is not generated between moving amounts of the two spools 30 even in a case where there is a difference in an external force applied to the spools 30. Thus, when a difference is generated between the moving amounts of the two spools 30 due to a difference in the external force, a coupling member 45 is inclined and a return spring 46 of a spool 30 with a large moving amount is bent more than a return spring 46 of a spool 30 with a small moving amount. When bent amounts of the two return springs 46 are different, a moment is applied to the coupling member 45 in a direction of recovering the inclination. As a result, the spool 30 with a large moving amount is pushed back or the return spring 46 of the spool 30 with a small moving amount is bent by the coupling member 45, whereby the moving amounts of the two spools 30 become identical to each other.
Thus, according to the hydraulic valve in which the coupling member 45 is arranged in such a manner as to bridge the two spools 30 and the return spring 46 is applied to the spools 30 through the coupling member 45, the above-described operation is repeatedly performed each time a difference is generated between the moving amounts of the two spools 30, and movement thereof is advanced without a large difference being generated between the two spools 30. Accordingly, a situation in which a gap is generated in oil supply control by the two spools 30 is prevented, and it becomes possible to accurately perform the oil supply control with respect to the hydraulic cylinder 1.
In the hydraulic valve of the embodiment, as illustrated un
Here, an advantage of providing the retainers 44 at the end parts of the spools 30 and making the coupling members 45 abut on the spools 30 through the retainers 44 will be described with reference to
Here, when an outer diameter of a sliding base part 31 in a spool 30: Dr, a pressure-receiving area of a spool 30: A, a distance between central axes of spools 30: L, a spring constant of a return spring 46: k, an attachment load of a return spring 46: f0, an allowance of an external force applied to two spools 30: F, and an allowable moving amount difference of two spools 30: s,
a force F1 to push back a first spool 30 with a large external force and a force F2 to push back a second spool 30 with a small external force are as follows.
F1=f0+F
F2=f0+k×s
From a balance of the forces, a pilot pressure Pp applied to a pressure chamber 42 is as follows.
Pp=(F1+F2)/2A
In consideration of a moment around a grounding point O between a sliding base part 31 and a coupling member 45 in the first spool 30, a counterclockwise moment M1 and a clockwise moment M2 are as follows.
M1=Pp×A×L=(F1+F2)×L/A
M2=(F1×Dr/2)+(F2×((Dr/2)+L))
In order to recover an inclined coupling member 45, the clockwise moment M2 needs to be larger than the counterclockwise moment M1. That is, it is necessary to satisfy the following expression.
M1−M2=((L−Dr)×F1/2)−((L+Dr)×F2/2)<0
Thus, in order to recover the inclined coupling member 45, it is only necessary to set an outer diameter Dr of the sliding base part 31 as large as possible. However, in a case where the outer diameter Dr of the sliding base part 31 is directly increased, it is also necessary to increase a distance L between central axes of the spools 30 due to a problem in strength of a valve main body 41, and the counterclockwise moment M1 is not reduced as intended.
In this respect, in a case where a retainer 44 is attached to an end part of a spool 30, a large-diameter part 44a of the retainer 44 abuts on a coupling member 45, and the counterclockwise moment M1 becomes similar to that of a case where an outer diameter Dr of a sliding base part 31 is increased. On the one hand, since the outer diameter Dr of the sliding base part 31 is not actually increased, it is not necessary to increase a distance L between central axes of the spools 30. As a result, it becomes possible to set the counterclockwise moment M1 small and the above-described effect becomes more outstanding when the retainer 44 is attached to the end part of the spool 30. Note that attachment of the retainer 44 to the end part of the spool 30 is not necessarily required in the present invention. A coupling member 45 may directly abut on a sliding base part 31 of a spool 30.
In the above-described embodiment, the hydraulic valve including the return spring 46 at each of both end parts of the spools 30 is exemplified. However, the present invention is not necessarily limited to this and may be also configured in a manner of the first modification example illustrated in
That is, in a hydraulic valve of the first modification example, a spool 30 including a guide shaft part 32 only at one end part of a sliding base part 31 is applied. At the other end part of the spool 30, a retainer 44 and a coupling member 45 are provided between the sliding base part 31 and the guide shaft part 32 in a manner similar to that of the embodiment.
On the one hand, at an end part placed on a left side of the guide shaft part 32 in
Also, in the hydraulic valve of the first modification example, an abutting wall part 48 is provided inside a housing box 40 that houses the guide shaft part 32 of the spool 30. The abutting wall part 48 can directly abut on the flange part 144a of the retainer 44 arranged on the left side, and the guide shaft part 32 and the stopper bolt 47 can be inserted into this. In this first modification example, each is configured in such a manner that an end surface of the flange part 144a abuts on both of the stopper bolt 47 and the abutting wall part 48 in a case where two spools 30 are arranged in a neutral position.
Note that configurations of a first drain port 12, a first actuator port 13, a pump port 14, a second actuator port 15, and a second drain port 16 provided in the valve base part 10 and configurations of a first annular groove 33, a second annular groove 34, and a third annular groove 35 provided in each of the spools 30 are similar to those of the embodiment. To a reference end surface 10a placed on the right side of the valve base part 10, a housing box 140 to cover two spool holes is attached.
In this hydraulic valve according to the first modification example, for example, when a pilot pressure is supplied to a pressure chamber 142 on the right side from a state of an arrangement in the neutral position illustrated in
On the one hand, when the pilot pressure is supplied to a pressure chamber 42 on the left side from the neutral position illustrated in
According to this hydraulic valve of the first modification example, since a configuration in which a return spring 46 is provided only at one end part of each spool 30 is included, it is possible not only to reduce the number of parts but also to reduce an inner volume of a housing box 40 provided on a right side of a valve base part 10 as much as possible and to reduce a space.
In each of the above-described embodiment and first modification example, a spool 30 in which a sliding base part 31 and a guide shaft part 32 are formed integrally is applied. However, the present invention is not necessarily limited to this. For example, a spool 130 including no guide shaft part 32 may be applied in a manner of the second modification example illustrated in
That is, in the second modification example illustrated in
In this hydraulic valve according to the second modification example, an operation is performed similarly to the first modification example and moving amounts of two spools 130 become identical to each other by a moment to recover the inclined coupling members 45 and 145 in a case where a difference is generated between the moving amounts of the two spools 130.
In any of the above-described embodiment, first modification example, and second modification example, a single coil spring is applied as a return spring 46. However, as described in the third modification example illustrated in
That is, in this third modification example, what includes a cylindrical spring seat 245b around an insertion hole 245a is applied as a coupling member 245, an internal coil spring 146b having a small diameter and a small wire diameter is arranged between facing parts in the spring seat 245b, and an external coil spring 146a having a large diameter and a large wire diameter is arranged between surfaces of a coupling member 45 placed around the spring seat 245b. Note that the other configuration is similar to that of the first modification example, and the same sign is assigned thereto.
In this hydraulic valve according to the third modification example, an operation is performed similarly to the first modification example and moving amounts of two spools 30 become identical to each other by a moment to recover the inclined coupling member 245 in a case where a difference is generated between the moving amounts of the two spools 30. In addition, since the return spring 146 includes the two coil springs 146a and 146b, it becomes possible to apply a pressing force identical to that of the first modification example to the spools 30 even when a spring length is short, and an effect of being able to reduce a space is also acquired.
In any of the above-described embodiment, and first modification example to third modification example, two spools 30 in which annular grooves 33, 34, and 35 have the same configuration are applied. However, the present invention is not necessarily limited to this. For example, as illustrated in
That is, in a hydraulic valve according to the fourth modification example, a pump port 312, actuator ports 313A and 313B, and a drain port 314 are provided in this order from a left side in the drawing in each of two spool holes 311 that are provided in a valve base part 310 and that are in parallel with each other. These ports 312, 313A, 313B, and 314 are formed in such a manner that positions in an axial direction thereof are identical to each other in the spool holes 311. Although each of the pump ports 312 and the drain ports 314 communicate with each other in the two spool holes 311, the actuator ports 313A and 313B are independent from each other in the spool holes 311.
A hydraulic pump 324 is connected to the pump ports 312 through a supply oil path 323, and a tank 322 is connected to the drain ports 314 through a drain oil path 321. A bottom chamber 1a of a hydraulic cylinder 1 is connected to an actuator port provided on an upper side in the drawing (hereinafter, referred to as upper actuator port 313A in case of being distinguished) through a bottom oil path 325, and a rod chamber 1b of the hydraulic cylinder 1 is connected to the other actuator port (hereinafter, referred to as lower actuator port 313B in case of being distinguished) through a rod oil path 326.
Spools 330A and 330B are respectively arranged in the spool holes 311. The spools 330A and 330B are columnar parts in which sliding base parts 331A and 331B and two guide shaft parts 332A and 332B are formed integrally and which have a round cross-section shape, and can move in the axial direction individually. The sliding base parts 331A and 331B have an outer diameter that can fit into the spool holes 311 of the valve base part 310. A length in the axial direction of the sliding base parts 331A and 331B is configured to be longer than a distance between reference end surfaces 310a. The guide shaft parts 332A and 332B are thin cylindrical parts provided on both end surfaces of the sliding base parts 331A and 331B, and are configured in such a manner that shaft centers thereof become identical to shaft centers of the sliding base parts 331A and 331B respectively.
In a spool placed on the upper side in the drawing (hereinafter, referred to as upper spool 330A in case of being distinguished), a first upper annular groove 333A, a second upper annular groove 334A, and a third upper annular groove 335A are provided in an outer peripheral surface of the sliding base part 331A. Similarly, in a spool placed on a lower side of the drawing (hereinafter, referred to as lower spool 330B in case of being distinguished), a first lower annular groove 333B, a second lower annular groove 334B, and a third lower annular groove 335B are provided in an outer peripheral surface of the sliding base part 331B. The first upper annular groove 333A of the upper spool 330A is to switch the pump ports 312 and the upper actuator port 313A between a communicating state and a blocked state. The second upper annular groove 334A is to switch the upper actuator port 313A between a state of communicating with the pump ports 312 and a state of communicating with the drain ports 314. The third upper annular groove 335A is to switch the upper actuator port 313A and the drain ports 314 between a communicating state and a blocked state. The first lower annular groove 333B of the lower spool 330B is to switch the pump ports 312 and the lower actuator port 313B between a communicating state and a blocked state. The second lower annular groove 334B is to switch the lower actuator port 313B between a state of communicating with the pump ports 312 and a state of communicating with the drain ports 314. The third lower annular groove 335B is to switch the lower actuator port 313B and the drain ports 314 between a communicating state and a blocked state.
Also, in the upper spool 330A, a first upper communication groove 336A is provided in the sliding base part 331A between the first upper annular groove 333A and the second upper annular groove 334A, and a second upper communication groove 337A is provided in the sliding base part 331A between the second upper annular groove 334A and the third upper annular groove 335A. Similarly, in the lower spool 330B, a first lower communication groove 336B is provided in the sliding base part 331B between the first lower annular groove 333B and the second lower annular groove 334B, and a second lower communication groove 337B is provided in the sliding base part 3318 between the second lower annular groove 334B and the third lower annular groove 335B. Although not clearly illustrated in the drawings, these communication grooves 336A, 336B, 337A, and 337B are formed in a plurality of positions at equal intervals along peripheral surfaces of the sliding base parts 331A and 331B. In the upper spool 330A, the first upper communication groove 336A and the second upper communication groove 337A are provided in such a manner as to be opened to the first upper annular groove 333A and the third upper annular groove 335A from an outer peripheral surface of the sliding base part 331A. On the other hand, in the lower spool 3308, the first lower communication groove 336B and the second lower communication groove 337B are provided in such a manner as to be opened to the second lower annular groove 334B from an outer peripheral surface of the sliding base part 331B.
More specifically, in a case where the two spools 330A and 330B are arranged in a neutral position illustrated in
When each of the spools 330A and 330B moves to a left side from the neutral position illustrated in
When each of the spools 330A and 330B moves to a right side from the neutral position illustrated in
Note that a point that a housing box 40 that configures, with the valve base part 310, a valve main body 341 of the hydraulic valve is provided on each of the two reference end surfaces 310a of the valve base part 310, a point that a retainer 44 is arranged at an end part of each of the spools 330A and 330B and a coupling member 45 is arranged in such a manner as to bridge the two spools 330A and 330B, and a point that a return spring 46 is arranged at an end part of each of the spools 330A and 330B are similar to those of the embodiment. Thus, the same sign is assigned with respect to these configurations and a detailed description thereof is omitted.
In the hydraulic valve according to the fourth modification example configured in the above manner, in a case where no pilot pressure is applied to pressure chambers 42 at both ends, each of the spools 330A and 330B is kept in the neutral position illustrated in
From this state, for example, as illustrated in
On the one hand, as illustrated in
According to this hydraulic valve according to the fourth modification example, the upper actuator port 313A connected only to the bottom chamber 1a of the hydraulic cylinder 1 and the lower actuator port 313B connected only to the rod chamber 1b are included. Thus, there is an advantage such as that a characteristic of the hydraulic cylinder 1 in a contraction operation and a characteristic thereof in an extension operation can be set individually.
In addition, in this hydraulic valve according to the fourth modification example, an operation is performed similarly to the embodiment and moving amounts of the two spools 330A and 330B become identical to each other due to a moment to recover the inclined coupling member 45 in a case where a difference is generated between the moving amounts of the two spools 330A and 330B. Accordingly, a situation in which a gap is generated in oil supply control by the two spools 330A and 330B is prevented, and it becomes possible to accurately perform the oil supply control with respect to the hydraulic cylinder 1.
Note that in each of the above-described embodiment and four modification examples, a hydraulic valve including two spools in a valve main body is exemplified. However, application is possible in a similar manner even when the number of spools is three or more. Also, although what performs oil supply control with respect to a hydraulic cylinder is exemplified, oil supply control can be obviously performed with respect to a different hydraulic pressure device.
Also, in any of the above-described embodiment and four modification examples, a hydraulic valve including two coupling members is exemplified. However, it is not necessarily required to provide two coupling members. For example, in a case where accuracy of a contraction operation of a hydraulic cylinder 1 is not demanded in an embodiment, it is sufficient when a coupling member 45 is provided only on a left side of a spool 30 and it is not necessary to provide a coupling member 45 on a right side of the spool 30. A different modification example is in a similar manner.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2018-058737 | Mar 2018 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2019/002327 | 1/24/2019 | WO | 00 |
