JP3839562B2 - Spool valve - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to reduction of fluid force acting on a spool valve.
[0002]
[Prior art]
Conventionally, as a structure that balances the fluid force acting on the spool in the spool valve (a structure that provides a compensation effect), for example, the Hanwabo “Hydraulic Drive and Control”, Vol. Such four-way flow control valves are known.
[0003]
As shown in FIG. 7, the four-way flow control valve includes a spool 2 that is slidable in a cylinder portion 1 </ b> A formed in the valve body 1. A plurality of annular ports are formed on the inner periphery of the cylinder portion 1A, and a pair of load ports 4 and 5 are provided on the left and right sides of the central supply port 3 to which the working fluid is supplied. A load 6 is interposed between the load ports 4 and 5. Further, a pair of return ports 7 and 8 are formed on the left and right outer sides of the load ports 4 and 5 so that the working fluid flows back to the drain side from these return ports 7 and 8.
[0004]
A pair of annular land portions 11 and 12 having substantially the same diameter as the cylinder portion 1A are formed on the outer periphery of the spool 2 corresponding to the positions of the load ports 4 and 5, and when the spool 2 is in the neutral position, The land portions 11 and 12 just close the load ports 4 and 5. A small-diameter portion 13 and bucket portions 14 and 15 are formed between the land portions 11 and 12 and on both left and right outer sides, respectively. As a result, when the spool 2 is shifted from the neutral position to the left and right, the working fluid from the supply port 3 flows into the load port 4 or 5 through the gap on the outer periphery of the small diameter portion 13 and operates from the load port 4 or 5. The fluid returns to the return port 7 or 8 through the outer periphery of the bucket portion 14 or 15.
[0005]
In this case, the bucket portions 14 and 15 on both outer sides of the land portions 11 and 12 have a specific shape in order to balance the working fluid pressure acting on the spool 2. That is, the spool 2 in the small-diameter portion 13 has a straight and substantially cylindrical shape, whereas the bucket portions 14 and 15 are formed with gentle inclined portions 14A and 15A on the left and right outer portions thereof. Further, inclined portions 7A and 8A are formed on the inner side walls of the return ports 7 and 8 (load ports 4 and 5 side), and the downstream side of the fluid passage from the load ports 4 and 5 to the return ports 7 and 8 is expanded. Yes.
[0006]
With such a configuration, the fluid force acting on the spool 2 is as described below.
[0007]
First, the fluid force exerted on the spool 2 by the fluid flowing from the supply port 3 to the load ports 4 and 5 will be described.
[0008]
As shown in FIG. 7, when the spool 2 moves to the right from the neutral position where the land portions 11 and 12 close the load ports 4 and 5, the supply port 3 and the right load port 5 communicate with each other. The working fluid from the supply port 3 flows into the load 6 through the load port 5 as indicated by arrows in the figure. In this case, the fluid flow is restricted by the opening between the load port 5 and the land portion 12, and the pressure of the working fluid is reduced. As a result, the spool 2 is caused to flow in the axial direction to be pulled back to the left in FIG. Physical strength works. The fluid force increases as the fluid passage between the load port 5 and the land portion 12 spreads and the flow rate increases.
[0009]
On the other hand, when the spool 2 moves to the left in FIG. 7 from the neutral position, the working fluid flows from the supply port 3 to the left load port 4. In this case, on the same principle as when the working fluid flows from the supply port 3 to the load port 5, a fluid force that attempts to pull back in the right direction in FIG. 7 acts on the spool 2.
[0010]
In this way, the fluid force acting on the spool 2 from the fluid flowing from the supply port 3 to the load ports 4 and 5 has a characteristic as shown by a one-dot chain line in the characteristic diagram of FIG. 8, and the spool 2 is pulled back to the neutral position side. Try to narrow (to narrow the opening of the load ports 4 and 5). In FIG. 8, the right direction in FIG. 7 is the positive direction.
[0011]
Next, the fluid force exerted on the spool 2 by the working fluid returning from the load port 4 or 5 to the return port 7 or 8 will be described.
[0012]
As shown in FIG. 7, when the spool 2 moves in the right direction (forward direction), the working fluid from the load 6 flows from the load port 4 to the return port 7. In this case, a part of the fluid that has flowed out to the bucket portion 14 side is guided from the inclined portion 14A of the bucket portion 14 to the inclined portion 7A of the return port, and flows in a vortex as indicated by an arrow in the figure. . As a result, the outflow momentum of the fluid flowing from the load port 4 to the return port 7 in the spool axial direction exceeds the inflow momentum, and the axial fluid force acting in the right direction (positive direction) in FIG. To do. This fluid force increases as the load port 4 or 5 spreads greatly due to an increase in the stroke of the spool 2 and the flow rate returning to the return port 7 or 8 increases.
[0013]
On the other hand, when the spool 2 moves in the left direction (negative direction) on the contrary, the fluid force from the fluid that flows in a vortex from the inclined portion 15A to the inclined portion 8A is expressed by the same principle as follows. The spool 2 is pushed out in the left direction (negative direction) in the figure.
[0014]
As described above, the fluid force exerted on the spool 2 by the working fluid returning from the load port 4 or 5 to the return port 7 or 8 has a characteristic indicated by a broken line in the characteristic diagram of FIG. 8, and pushes the spool 2 from the neutral position side. Trying to do so (expand the opening of the load ports 4 and 5).
[0015]
In the four-way flow control valve, the fluid force exerted on the spool 2 by the fluid flowing from the supply port 3 to the load ports 4 and 5 by making the shape of the bucket portion 14 and the return port 7 appropriate, The hydraulic force exerted on the spool 2 by the working fluid returning from the load port 4 or 5 to the return port 7 or 8 is just balanced. That is, the total fluid force acting on the spool 2 is suppressed to a substantially minimum regardless of the displacement of the spool 2, as shown by the solid line in FIG.
[0016]
As shown in FIG. 9, such a four-way flow control valve has a spring 16 that exerts a force from the left end of the spool 2 to the right direction (forward direction), and a left direction from the right end of the spool 2 by energization ( A proportional solenoid 17 is provided which exerts a force in the negative direction). In FIG. 9, a sleeve 20 is interposed between the valve body 1 and the spool 2, but the essential structure of the four-way flow control valve is the same as that in FIG. The sleeve 20 is fixed to the valve body 1, and an opening for flowing the working fluid is formed in accordance with the positions of the supply port 3, the load ports 4 and 5, and the return ports 7 and 8. .
[0017]
The axial displacement of the spool 2 is driven by the balance of the urging forces from the spring 16 and the proportional solenoid 17. That is, the sum of the fluid force acting on the spool 2 and the force from the spring 16 has a characteristic as shown by a solid line in FIG. 10, which is a characteristic diagram in which the force from the spring 16 is superimposed on FIG. By controlling the energization amount to 17, the urging force from the proportional solenoid 17 is appropriately adjusted to balance the spool 2 with a desired displacement.
[0018]
[Problems to be solved by the invention]
Thus, as long as the flow control valve shown in FIGS. 7 and 9 is used as a four-way valve, the fluid force acting on the spool 2 is balanced.
[0019]
However, it may be desired to use this four-way flow control valve as a two-way valve or a three-way valve. In such a case, the fluid force acting on the spool 2 is not balanced and cannot be minimized. For this reason, the axial fluid force acting on the spool 2 is a combination of the fluid force from the fluid flowing from the supply port 3 to the load ports 4 and 5 and the spring force, as shown by the dashed line in FIG. Depending on the displacement position of the spool 2, it becomes a large value.
[0020]
Further, even when the flow control valve shown in FIGS. 7 and 9 is used as a four-way valve, when a single rod cylinder is used as the load 6, the flow rate flowing from the supply port 3 into the load port 4 or 5, The flow rate of reflux from the load port 4 or 5 to the return port 7 or 8 may not be the same, the fluid force may be unbalanced, and a large axial fluid force may act on the spool 2.
[0021]
In order to counter such a large fluid force, it is necessary to enlarge the proportional solenoid 17, which causes an increase in cost, a decrease in dynamic characteristics of the proportional solenoid 17, and the like.
[0022]
The present invention has been made paying attention to such a problem, and an object of the present invention is to provide a spool valve capable of reducing the fluid force acting on the spool regardless of the use state of the valve.
[0023]
[Means for Solving the Problems]
The first invention includes a spool slidable on the left and right of the neutral position, a supply port, a pair of load ports provided on the left and right sides of the supply port, and a pair provided on both outer sides of the load ports. A return port, spring means for urging the spool in one of the left and right directions, and a proportional solenoid for urging the spool in either the left or right direction when energized, and when the spool is in a neutral position A pair of land portions formed on the spool block the pair of load ports, and when the spool slides to the left and right of the neutral position, the supply port, one of the load ports, the other of the load ports, and the return in the spool valve for communicating the port, intermediate the pair of the land portions of the spool, a the substantially the same diameter and a pair of land portions, said spool Will give throttle the fluid passage flowing from the supply port according to stroke, when said spool is slid beyond the rated stroke to one of the lateral direction closes one said of said supply port flanged In addition, the fluid flows through the pair of load ports through a plurality of openings that extend from the left and right ends of the load port in the spool axial direction with a length substantially equal to the rated stroke of the spool. did.
[0024]
In the second invention, the plurality of openings are formed inside the load port along the left and right edges of the load port .
[0027]
Operation and effect of the invention
In the first and second aspects of the invention, when the spool valve is operated, the fluid flowing from the supply port to the load port is throttled by the load port and exerts a fluid force on the spool. Therefore, the force by which the fluid force pulls the spool in the direction of closing the load port does not become so great even if the stroke of the spool advances. Further, when the stroke of the spool advances to some extent, the effect of the throttle that the brim-shaped land portion gives to the fluid flowing in from the supply port comes into effect, so this fluid force pushes the spool in the direction to open the load port, The fluid force that pulls the spool in the direction of closing the port reaches a peak. Therefore, the characteristics of the force exerted on the spool by the fluid flowing from the supply port to the load port are undulated above and below the fluid force zero, and the absolute value of the fluid force is suppressed to a small value.
When the spool further slides beyond the rated stroke, the collar-like land blocks the right or left side of the supply port. In this way, when the sliding of the spool exceeds a predetermined value, the left and right sides of the supply port are blocked by one of the collar-shaped land portion and the pair of land portions, and the inflow of working fluid from the pump side is prohibited. The fail-safe function works.
[0028]
Further, since a large outflow angle is given to the fluid flowing out from the load port to the return port side, the force exerted on the spool by the fluid flowing from the load port to the return port does not become so large even if the stroke of the spool advances.
[0029]
As described above, according to the present invention, both the fluid force exerted on the spool by the fluid flowing from the supply port to the load port and the fluid force exerted on the spool by the fluid flowing from the load port to the return port are suppressed within a relatively small range. Therefore, regardless of how the spool valve is used, the absolute value of the sum of the fluid force and the spring force does not become too large. Therefore, it is not necessary to increase the thrust of the proportional solenoid that generates an urging force that opposes the fluid force and the spring force.
[0030]
Further, if the length of apertures equal length and substantially the nominal stroke of the spool, when the spool is slid beyond the rated stroke, the land portion will be moved to beyond the end of the opening In addition, the effective passage area of the load port does not expand further. Therefore, even if the spool slides beyond the rated stroke, the flow rate does not increase and an uncontrollable fluid force does not act on the spool.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0033]
As shown in FIG. 1, in the spool valve of the present invention, a sleeve 20 is fixed to a cylinder portion 1 </ b> A formed in the valve body 1, and the spool 2 is slidably accommodated in the sleeve 20.
[0034]
A plurality of annular ports are formed on the inner circumference of the cylinder portion 1A, and the supply port 3 communicates with the pump 9 among these. A pair of load ports 4 and 5 are provided on the left and right sides of the supply port 3, and a load 6 is interposed between the load ports 4 and 5. Further, a pair of return ports 7 and 8 are formed on both the left and right outer sides of the load ports 4 and 5, and the working fluid returns to the tank 10 side from these return ports 7 and 8.
[0035]
As shown in FIG. 2, the outer periphery of the spool 2 has a diameter approximately the same as the inner diameter of the sleeve 20 at a position just corresponding to the load ports 4 and 5 when the spool 2 is in the neutral position. A pair of ring-shaped land portions 11 and 12 having substantially the same length as the axial length of each are formed. A small-diameter portion 13 and bucket portions 14 and 15 are formed between the land portions 11 and 12 and on both left and right outer sides, respectively. Incidentally, the bucket portion 14 and 15, FIG. 7, similarly to the conventional example shown in FIG. 9, the inclined portions 14A in the lateral outer to direct the fluid flowing through the ports 7 and 8 return from the load port 4, 5, 15 A It has.
[0036]
Further, as a feature of the present invention, a brim-shaped land portion 19 having a short axial length and substantially the same diameter as the inner diameter of the sleeve 20 is provided substantially at the center of the small diameter portion 13. The land portion 19 is configured to restrict the fluid passage that flows out from the supply port 3 as the spool 2 strokes.
[0037]
As shown in FIGS. 3 and 4, annular recesses 21, 22, and 23 are formed on the inner circumferences of the sleeve 20 corresponding to the supply port 3 and the return ports 7 and 8, respectively. A plurality of circular holes 31, 32, and 33 are opened in these annular recesses 21, 22, and 23, respectively. These circular holes 31, 32, 33 are provided side by side along the annular recesses 21, 22, 23, and the working fluid passes through these circular holes 31, 32, 33 and returns to the supply port 3. It circulates between the ports 7 and 8 and the inside of the sleeve 20.
[0038]
Further, at positions corresponding to the load ports 4 and 5 of the sleeve 20, a plurality of rectangular holes 24 and 25 and rectangular holes 26 and 27, respectively, are arranged along the circumferential direction of the sleeve 20 as a characteristic feature of the present invention. Are formed side by side.
[0039]
In this case, the rectangular holes 24 and 25 and the rectangular holes 26 and 27 are symmetrically arranged inside the load ports 4 and 5 so as to be at least a pair along the left and right edges of the load ports 4 and 5, respectively. It is formed. The lengths (widths along the axial direction) of these rectangular holes 24 to 27 are set to be substantially the same as the rated stroke of the spool 2 or slightly longer than the rated stroke. Thus, while the spool 2 slides within the rated stroke, the rectangular holes 24 and 26 or the rectangular holes 25 and 27 closed by the land portions 11 and 12 according to the stroke of the spool 2 in the right or left direction. Open, and the fluid passage from the supply port 3 to the load port 5 or 4 and the fluid passage from the load port 4 or 5 to the return port 7 or 8 expand. However, even if the spool 2 slides beyond the rated stroke, the land 11 or 12 only moves beyond the ends of the rectangular holes 24, 25 or 26, 27, and the effective passage area is further increased. It does not spread.
[0040]
Although not shown in FIG. 1, springs 16 and proportional solenoids 17 are provided at both left and right ends of the spool 2 as in FIG. 9, and the displacement of the spool 2 is caused by energizing the proportional solenoid 17. It is controlled by adjusting the biasing force from.
[0041]
Next, the operation will be described.
[0042]
When the spool valve is used, the proportional solenoid 17 is appropriately energized by, for example, feedback control to control the displacement amount of the spool 2, that is, the valve opening degree. In this case, the working fluid from the pump 9 reaches the load 6 from the supply port 3 through the load ports 4 and 5, and returns to the tank 10 through the return port 7 or 8. Exerts a fluid force on the spool 2.
[0043]
First, the fluid force exerted on the spool 2 by the fluid flowing from the supply port 3 to the load port 4 or 5 will be described.
[0044]
When the spool 2 moves in the right direction (forward direction) from the neutral position where the land portions 11 and 12 close the load ports 4 and 5, the working fluid flows between the supply port 3 and the land portion 19. And flows into the load port 5 from a rectangular hole 26 partially closed by the land portion 12. In this case, due to the pressure drop of the fluid passing through the fluid passage between the rectangular hole 26 and the land portion 12, a fluid force in the left direction (negative direction) acts on the spool 2, and as shown by a one-dot chain line in FIG. This negative fluid force increases with the positive stroke of the spool 2. In this case, in the present invention, due to the presence of the rectangular hole 26, the outflow angle of the fluid to the load port 5 is increased, and an increase in the negative fluid force is suppressed.
[0045]
Further, in the present invention, when the forward stroke of the spool 2 advances to some extent, the fluid throttled in the fluid passage between the supply port 3 and the land portion 19 now moves the land portion 19 (and hence the spool 2) to the right. The force to pull in in the direction (positive direction) is effective. This positive direction fluid force becomes more dominant as the forward stroke of the spool 2 advances and the fluid passage between the supply port 3 and the land portion 19 becomes narrower. The total fluid force exerted on the spool 2 by the flowing fluid reaches its peak in the negative direction as shown by the one-dot chain line in FIG.
[0046]
On the other hand, when the spool 2 moves in the left direction (negative direction), the working fluid flows into the load port 4 from between the supply port 3 and the land portion 19, between the land portion 11 and the rectangular hole 25. However, the fluid force acting on the spool 2 at this time is generated completely symmetrically when the spool 2 moves in the right direction (positive direction) and right and left (positive and negative).
[0047]
As described above, the fluid force exerted on the spool 2 by the fluid flowing from the supply port 3 to the load port 4 or 5 becomes a wave shape as shown by a one-dot chain line in FIG. 5, and is within a relatively narrow range above and below the zero fluid force. Limited to
[0048]
Next, the fluid force exerted on the spool 2 by the working fluid returning from the load port 4 or 5 to the return port 7 or 8 will be described.
[0049]
When the spool 2 moves in the right direction (forward direction), the working fluid from the load 6 flows from the load port 4 through the rectangular hole 24 to the return port 7. In this case, in the present invention, due to the presence of the rectangular hole 24, the inflow angle of the fluid from the load port 4 can be increased, so that the fluid force toward the right direction (positive direction) is shown in FIGS. As in the conventional example shown in FIG. Further, by adjusting the shape of the inclined portion 14A of the bucket portion 14, a negative fluid force is once generated at the initial stage of the stroke of the spool 2, and then the fluid force is turned in the positive direction. .
[0050]
On the other hand, when the spool 2 moves in the left direction (negative direction), the working fluid from the load 6 flows from the load port 5 through the rectangular hole 27 to the return port 8, but in this case, When the spool 2 moves in the right direction (positive direction), the fluid force acts completely symmetrically on the left and right (positive and negative).
[0051]
As described above, the fluid force exerted on the spool 2 by the working fluid returning from the load port 4 or 5 to the return port 7 or 8 is also limited to a relatively narrow range above and below the zero fluid force, as indicated by a broken line in FIG. Is done.
[0052]
Therefore, as indicated by a solid line in FIG. 5, the total amount of fluid exerted on the spool 2 by the fluid flowing from the supply port 3 to the load port 4 or 5 and the working fluid returning from the load port 4 or 5 to the return port 7 or 8 is affected. The fluid force is also limited to a relatively narrow range above and below the zero fluid force.
[0053]
FIG. 6 shows the characteristics of the force obtained by adding the spring force of the spring 16 to the three types of fluid forces shown in FIG. Thus, the absolute value of the sum of the fluid force and the spring force is limited to a relatively small range for any of the three types of fluid force. That is, when the fluid flows only from the supply port 3 to the load port 4 or 5 (in the case of the dashed line in FIG. 6), when the fluid flows only from the load port 4 or 5 to the return port 7 or 8 (indicated by the broken line in FIG. 6). In any case, when the fluid flows from the supply port 3 to the return port 7 or 8 (in the case of the solid line in FIG. 6), the spool valve of the present invention can be flown in any way. The absolute value of the sum of physical strength and spring force never becomes too large. Therefore, it is not necessary to increase the size of the proportional solenoid 17 that generates an urging force that opposes the fluid force and the spring force.
[0054]
The operation accompanying the sliding of the spool 2 within the rated stroke is as described above. However, in the present invention, when the spool 2 slides exceeding the rated stroke, the land portions 11 and 12 are rectangular holes. It moves to the place beyond 24 to 27, and the opening of the load ports 4 and 5 does not expand beyond being limited by the rectangular holes 24 to 27. Therefore, even if the spool 2 slides beyond the rated stroke, the flow rate does not increase and an uncontrollable fluid force does not act on the spool 2.
[0055]
When the spool 2 further slides beyond the rated stroke, the land portion 19 exceeds the right or left end of the annular recess 21 and blocks the right or left side of the supply port 3. In this way, when the sliding of the spool 2 exceeds a predetermined value, the left and right sides of the supply port 3 are blocked by the land portion 19 and the land portion 11 or 12, and the inflow of working fluid from the pump 9 side is prohibited. Fail-safe function is working.
[0056]
In addition, in this invention, it can replace with the rectangular holes 24-27 in this embodiment, and can also employ | adopt another embodiment using a hole (for example, circular hole) of a different shape. Even in this case, these holes are formed inside the load ports 4 and 5 along the left and right edges of the load ports 4 and 5, and the length along the axial direction of the spool 2 is set. The length may be set to be approximately the same length as the rated stroke or slightly longer than the rated stroke.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an embodiment of the present invention.
FIG. 2 is a side view showing the spool.
FIG. 3 is a cross-sectional view showing a sleeve.
4 is a cross-sectional view taken along the line AA in FIG.
FIG. 5 is a characteristic diagram showing characteristics of a fluid force acting on the spool in the same manner.
FIG. 6 is a characteristic diagram showing the total characteristics of fluid force and spring force acting on the spool.
FIG. 7 is a cross-sectional view showing a conventional example.
FIG. 8 is a characteristic diagram showing characteristics of a fluid force acting on the spool in the same manner.
FIG. 9 is a cross-sectional view showing a conventional example.
FIG. 10 is a characteristic diagram showing the total characteristics of the fluid force and the spring force acting on the spool.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Valve body 2 Spool 3 Supply port 4 Load port 5 Load port 6 Load 7 Return port 8 Return port 9 Pump 10 Tank 11 Land part 12 Land part 13 Small diameter part 14 Bucket part 15 Bucket part 19 Land part 20 Sleeve 21 Annular recessed part 22 Annular recess 23 Annular recess 24 Rectangular hole 25 Rectangular hole 26 Rectangular hole 27 Rectangular hole 31 Circular hole 32 Circular hole 33 Circular hole

Claims (2)

A spool that can slide on the left and right of the neutral position;
A supply port;
A pair of load ports provided on the left and right sides of the supply port;
A pair of return ports provided on both outer sides of these load ports;
Spring means for urging the spool in either the left or right direction;
A proportional solenoid that energizes the spool in either the left or right direction when energized;
When the spool is in the neutral position, a pair of land portions formed on the spool block the pair of load ports, and when the spool slides to the left or right of the neutral position, one of the supply port and the load port And a spool valve communicating the other of the load ports and the return port,
Between the pair of land portions of the spool, the diameter is substantially the same as that of the pair of land portions, and a throttle is given to a fluid passage that flows out from the supply port as the spool strokes. When one of the directions slides beyond the rated stroke, a flange-shaped land portion is provided for closing the one of the supply ports, and the fluid flow in the pair of load ports is at the left and right ends of the load ports. A spool valve characterized in that the spool valve is formed through a plurality of openings extending from the portion in the axial direction of the spool in a length substantially equal to the rated stroke of the spool.   2. The spool valve according to claim 1, wherein the plurality of openings are formed inside the load port along left and right edges of the load port. 3.

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