JP2019159784A - Flow control valve - Google Patents

Abstract

To provide a flow control valve capable of keeping a flow rate of a fluid constant regardless of a change in a load while a through hole provided in a piston that moves for pressure compensation functions properly as a passage for a working fluid to pass through, and improving a stability of a fluid pressure circuit.SOLUTION: A first through hole 12e and a second through hole 12f are provided in a piston 12 which is arranged so that an opening degree of a communication between an inlet portion 11a and an outlet portion 11b of a casing 11 can be adjusted; under such a condition that the piston 12 is trying to close a flow path between the inlet portion 11a and the outlet portion 11b, since a fluid can flow from the inlet portion 11a to the outlet portion 11b through the second through hole 12f facing the inlet portion 11a and the first through hole 12e communicating with the outlet portion 11b, a direction in which the fluid flows immediately before closing is different from a moving direction of the piston 12, so that a behavior of the piston is less affected by the fluid, and a stability of a fluid pressure circuit can be improved.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a flow rate adjusting valve with pressure compensation used in a fluid pressure circuit.

  Hydraulic actuators, especially hydraulic motors used as drive sources for hydraulic excavators and winches, switch the forward / reverse switching and transition to the stopped state by changing the hydraulic supply state to the hydraulic motor with a hydraulic circuit equipped with a directional switching valve. In general, it is realized by changing.

  In an apparatus equipped with a hydraulic circuit for such a hydraulic motor, when hydraulic oil supplied from a pressure source (pump) for generating hydraulic pressure is introduced as it is into a directional switching valve to control the operation of the hydraulic motor, The hydraulic oil pressure toward the hydraulic motor also changes due to the fluctuation of the hydraulic oil, and the hydraulic oil supply amount to the hydraulic motor changes.For example, in a high load state, the hydraulic oil flow rate increases as the hydraulic oil pressure increases. There is a problem that the operating speed of the hydraulic motor is reduced.

For this reason, a flow rate adjusting valve with pressure compensation is provided on the upstream side of the direction switching valve, and the flow rate of hydraulic oil supplied to the hydraulic motor is set by the direction switching valve (operation valve) even if the load on the hydraulic motor changes. A mechanism has been introduced that remains constant from the value.
An example of such a flow rate adjusting valve with pressure compensation is disclosed in Japanese Patent Laid-Open No. 11-63250.

JP-A-11-63250

  The conventional flow rate adjustment valve with pressure compensation is configured as described above, and can make the flow rate of hydraulic oil supplied to the actuator, etc. of the rear stage constant without changing from the set value, regardless of changes in the load. there were. However, a spool (piston) that adjusts the flow passage area between the inlet portion and the outlet portion of the hydraulic fluid passage in the valve device by movement corresponds to the relative increase in the hydraulic fluid pressure that flows in. When moving so as to close, the large diameter part of the spool rapidly narrows the annular cross-sectional flow path around the spool, thereby changing the pressure difference between the inlet and outlet parts of the flow path. There was a risk that the degree would increase, causing noise and hunting in other valve devices provided on the rear stage side.

  For this reason, notches are provided at a plurality of locations in the portion where the spool transitions from the large diameter portion to the small diameter portion so that the hydraulic fluid can flow from the inlet portion to the outlet portion through the notched portion. Conventionally, a valve structure has been adopted that moderates the narrowing of the cross-sectional area of the flow path around the spool just before closing the path and relaxes the change in pressure difference between the inlet and outlet of the flow path. It was.

  However, when such a notch is provided in the spool, the hydraulic oil notch flows when the hydraulic oil flows from the inlet portion through the notch portion of the spool to the outlet portion immediately before the spool closes the flow path. Since the flow direction in the part becomes the same as the moving direction of the spool, the spool behavior becomes unstable, such as suddenly shifting to the closed state under the influence of the flow of hydraulic oil in the notch part, It affects the other valve devices on the rear stage, such as hunting, and the movement of the spool cannot properly follow the change in hydraulic oil pressure due to load fluctuations. It had the problem of end.

  The present invention has been made to solve the above problems, and when a piston moving for pressure compensation attempts to close a flow path, a through hole provided in the piston is operated from an inlet portion to an outlet portion. By properly functioning as a passage for fluid, the flow rate of fluid can be kept constant regardless of changes in load, and the stability of the fluid pressure circuit can be improved without adversely affecting other valve devices on the rear stage, such as hunting. An object of the present invention is to provide a flow control valve that can be improved.

  A flow rate adjusting valve according to the present invention includes a casing having an inlet portion and an outlet portion for fluid, a piston that is slidably fitted into the casing, and that adjusts the opening degree of communication between the inlet portion and the outlet portion. The casing is provided with a first pressure receiving portion facing one end of the piston and a second pressure receiving portion facing the other end of the piston, and the fluid on the upstream side in the throttle mechanism leading to the outlet portion of the casing The pressure is introduced into the first pressure receiving portion, the fluid pressure on the rear stage side of the throttle mechanism is introduced into the second pressure receiving portion, the piston is moved based on the pressure difference before and after the throttle mechanism, and the inlet portion In the flow rate adjusting valve with pressure compensation for adjusting the opening degree of communication between the outlet and the outlet portion, the piston is positioned on one end side and faces the inlet portion and slidably contacts the casing; Slid on the casing A second large-diameter portion that is positioned between the first large-diameter portion and the second large-diameter portion and is smaller than the large-diameter portion and has a small-diameter portion facing the outlet portion. The first pressure receiving portion receives a pressing force in a direction to reduce the opening degree of communication between the inlet portion and the outlet portion with a piston, and the piston from the second pressure receiving portion is between the inlet portion and the outlet portion. A curved surface that is configured to receive a pressing force in a direction that increases the degree of communication opening, and that changes in diameter in a tapered manner from the large diameter portion toward the small diameter portion between the first large diameter portion and the small diameter portion of the piston. A tapered portion is formed, a first through hole is formed in at least the tapered portion of the piston in a direction perpendicular to the longitudinal direction of the piston, and the longitudinal direction of the piston is formed in at least the first large diameter portion of the piston. In a direction perpendicular to the direction and closer to one end of the piston than the first through hole. A through hole is bored in, the second through holes, is to communicate to intersect the portion of the first through hole.

  As described above, according to the present invention, the piston disposed in the casing so that the opening degree of the communication between the inlet portion and the outlet portion can be adjusted includes the two large diameter portions, the small diameter portion and the tapered portion sandwiched between them. A first through hole is provided in a predetermined range including at least a tapered portion of the piston, and a second through hole is provided in a predetermined range including at least the first large diameter portion, In a state where the second through hole that is closer to one end of the piston than the through hole of the crossing and communicating with the first through hole, the piston tries to close the flow path between the inlet portion and the outlet portion, Through the second through hole in the first large diameter part facing the inlet part and the first through hole facing the gap between the small diameter part leading to the outlet part and the casing, from the inlet part to the outlet part side The fluid can flow through the second through hole at the inlet. By continuing for a while, the direction in which the fluid flows from the inlet to the outlet immediately before closing is different from the direction of movement of the piston, and the piston behavior is less affected by the fluid, and the piston is pressure compensated. The original adjustment function that keeps the flow rate of the fluid constant regardless of the change in fluid pressure due to load fluctuations can be performed correctly, and the unstable behavior of the piston can be suppressed to prevent This prevents sudden changes in fluid pressure that can lead to abnormalities such as hunting, and improves the stability of the fluid pressure circuit.

  In addition, only by providing two through-holes at a predetermined position of the piston, the working fluid between the inlet and the outlet when the piston tries to close the flow path between the inlet and the outlet. Therefore, it is possible to form a suitable passage through which the valve device having the optimum characteristics can be obtained easily.

  In addition, in the flow rate adjusting valve according to the present invention, the cross-sectional area of the second through hole in the piston is smaller than the cross-sectional area of the first through hole, if necessary.

  As described above, according to the present invention, the second through-hole formed in the piston is made smaller than the first through-hole, and the piston is in the state where the piston tries to close between the inlet and the outlet. While the fluid is directed from the second through hole facing the part to the outlet side through the first through hole, the second through hole acts as a throttle on the fluid to reduce the pressure of the fluid. The pressure of the fluid that reaches the outlet through the two through holes and the first through hole can be set to an appropriate magnitude, and the flow of the fluid on the outlet side can be maintained in a stable state. Therefore, it is possible to restrict the flow of the fluid, to prevent the fluid from reaching the outlet portion excessively and causing a sudden change in the flow, and to more reliably prevent adverse effects such as hunting in the valve device on the rear stage side.

  In addition, the flow rate adjusting valve according to the present invention is configured such that the second through hole in the piston extends over the first large diameter portion and the tapered portion, and the first large diameter of the holes, if necessary. The hole portion positioned in the portion is formed by being biased toward the first large-diameter portion so as to be larger than the hole portion positioned in the tapered portion.

  As described above, according to the present invention, the second through-hole drilled in the predetermined range straddling the first large-diameter portion and the tapered portion of the piston is the hole portion provided in the first large-diameter portion. Is larger than the hole portion provided in the tapered portion, and is arranged so as to be biased toward the first large-diameter portion side. In the state where the boundary portion between the first large diameter portion and the taper portion of the piston reaches the end portion of the inlet portion, a part of the fluid is formed in the opening portion of the second through hole. , After entering from the first large-diameter portion side region of the second through-hole, exiting from the tapered portion-side region, proceeding through the gap between the small-diameter portion and the casing and reaching the outlet portion, that is, While producing a flow in the same direction as the piston movement direction, this fluid flows in the same direction as the piston movement direction. The flow rate of the fluid is limited to a small percentage of the fluid flow rate toward the outlet side through the second through hole and the first through hole, so that the fluid flow hardly affects the piston. The stability of the fluid pressure circuit can be secured by limiting the piston behavior to that relating to pressure compensation.

  In addition, in the flow rate adjusting valve according to the present invention, the first through hole and the second through hole in the piston are formed so as to be orthogonal to each other as necessary.

  As described above, according to the present invention, the first through hole provided in the piston and the second through hole are positioned so as to be orthogonal to each other, and the opening portion of the first through hole and the second through hole are opened. By separating the portion from the piston surface as much as possible, while the piston tries to close the gap between the inlet portion and the outlet portion, the flow of the fluid flowing in the inlet portion into the second through-hole and the fluid The flow from the one through hole to the outlet part does not affect each other, and the inflow of the fluid into the second through hole and the outflow from the first through hole are performed smoothly. In addition to making it difficult for abnormalities such as sudden changes in pressure to occur, it is possible to maintain the stability of the fluid pressure circuit by preventing the flow of fluid from affecting the behavior of the piston.

It is schematic structure explanatory drawing of the valve apparatus using the flow regulating valve concerning one Embodiment of this invention. 1 is a schematic configuration diagram of a hydraulic circuit for driving a hydraulic motor including a flow rate adjusting valve according to an embodiment of the present invention. It is a communicating state explanatory view of a pressure port and one load side port in a direction change valve in a valve device using a flow regulating valve concerning one embodiment of the present invention. It is communication state explanatory drawing of the pressure port and the other load side port in the direction switching valve in the valve apparatus using the flow regulating valve concerning one embodiment of the present invention. It is hydraulic oil distribution allowable state explanatory drawing of the flow regulating valve concerning one embodiment of the present invention. It is a movement state explanatory view to the opening degree increase side of the piston in the flow regulating valve concerning one embodiment of the present invention. It is explanatory drawing which showed the 1st through-hole longitudinal cross-section in the sliding contact start state to the passage part side inner peripheral surface of the 1st large diameter part in the piston of the flow regulating valve which concerns on one Embodiment of this invention. It is explanatory drawing which showed the 2nd through-hole longitudinal cross-section in the sliding contact start state to the passage part side inner peripheral surface of the 1st large diameter part in the piston of the flow regulating valve which concerns on one Embodiment of this invention. It is explanatory drawing which showed the 1st through-hole longitudinal cross-section in the arrival state to the inlet part outer side position of the 1st through-hole in the piston of the flow regulating valve concerning one Embodiment of this invention. It is explanatory drawing which showed the 2nd through-hole longitudinal cross-section in the arrival state to the inlet part outer side position of the 1st through-hole in the piston of the flow regulating valve concerning one Embodiment of this invention. FIG. 6 is an explanatory diagram of a state where the second through hole reaches the outer position of the inlet portion of the piston of the flow rate adjusting valve according to the embodiment of the present invention.

  Hereinafter, a flow regulating valve according to an embodiment of the present invention will be described with reference to FIGS. In this embodiment, the valve is mainly a directional switching valve that is provided in a hydraulic circuit that circulates hydraulic oil and drives a hydraulic motor as an actuator, and that switches or adjusts the distribution state of the hydraulic oil to the hydraulic motor. An example of a flow rate adjusting valve with pressure compensation applied to the apparatus will be described.

  In each of the drawings, the flow rate adjusting valve 10 according to the present embodiment is used as an integral valve device 90 in combination with the direction switching valve 20, and the casing 11 in common with the direction switching valve 20 and the casing 11. It is the structure provided with the piston 12 incorporated and the spring 13 which adjusts the position of this piston 12 with an elastic force.

  In this flow regulating valve 10, the position of the piston 12 incorporated in the casing 11 is adjusted by the pressure of the hydraulic oil before and after the throttle mechanism at the rear stage and the elastic force of the spring 13, and the opening of the hydraulic oil passage is changed to operate. The pressure of the oil is automatically controlled so that the hydraulic oil having a flow rate determined according to the position of the spool 21 can be supplied to the load side without being influenced by the load or the pressure source by the rear direction switching valve 20. The basic mechanism related to pressure compensation is the same as that of a known flow rate adjusting valve with pressure compensation, and detailed description thereof is omitted.

  The valve device 90 has a configuration in which a set of the direction switching valve 20 and the flow rate adjustment valve 10 is integrated, and is used together with other hydraulic equipment such as a counter balance valve 65 to form a hydraulic circuit. The actuator 30 is connected to the power source 30 and the low-pressure unit 40 and controls the operation of the hydraulic motor 50 as an actuator.

  The direction switching valve 20 used in combination with the flow rate adjusting valve 10 includes a substantially cylindrical spool 21 that is mounted in the casing 11 in common with the flow rate adjusting valve 10 so as to be movable in the longitudinal direction. By switching the connection between the pressure port 23 and the low pressure ports 24 and 25 provided in the casing 11 and the two load side ports 26 and 27 by manual switching, supply and discharge of hydraulic oil to and from the load side hydraulic motor 50 is performed. It is a known valve for switching between.

  The pressure switching port 23 of the direction switching valve 20 is connected to the flow rate adjusting valve 10 and the low pressure ports 24 and 25 are connected to the low pressure section 40, while the load side ports 26 and 27 are reversely rotated from the forward rotation side of the hydraulic motor side circuit. Are connected to the two flow paths 61 and 62 on the side.

  This directional switching valve 20 has a neutral state in which the two load-side ports 26 and 27 are not connected to either the pressure port 23 and the low-pressure ports 24 and 25, respectively, and the pressure port 23 is connected to one load side. A state where the low pressure port 25 communicates with the other load side port 27 and communicates with the port 26 and the hydraulic motor 50 rotates in the forward rotation direction, and a pressure port 23 communicates with the other load side port 27 The port 24 communicates with one load side port 26 and is configured to be a three-position type capable of switching between a state in which the hydraulic motor 50 is rotated in the reverse rotation direction.

  In the spool 21, recesses serving as throttle portions 21 c and 21 d are formed in both end portions of the large diameter portion facing the pressure port 23 in the neutral state, and the direction switching valve 20 is connected to the pressure port 23 and the load side port. In a state in which any one of 26 and 27 is communicated, the hydraulic oil reaches the load side port 26 from the pressure port 23 via the throttle portion 21c or the load side port 27 via the throttle portion 21d.

  The casing 11 is common to the direction switching valve 20, and has an inlet 11 a connected to a pressure source 30 such as a pump to introduce hydraulic oil as a configuration corresponding to the flow rate adjustment valve 10, and a direction switching valve. And 20 outlet ports 11b connected to the pressure port 23.

  Further, the casing 11 is provided with a first pressure receiving portion 11 c facing one end portion of the piston 12 and a second pressure receiving portion 11 d facing the other end portion of the piston 12. The first pressure receiving portion 11 c communicates with the outlet portion 11 b, and the second pressure receiving portion 11 d communicates with the secondary pressure passage 11 e provided in the casing 11.

  As a result, the hydraulic oil pressure on the upstream side of the throttle portions 21c and 21d of the direction switching valve 20 serving as a throttle mechanism that communicates with the outlet portion 11b of the casing 11 is introduced into the first pressure receiving portion 11c through the outlet portion 11b. The hydraulic oil pressure on the downstream side of the throttle portions 21c and 21d of the switching valve 20 is introduced into the second pressure receiving portion 11d via the secondary pressure passage 11e that can communicate with the throttle portions 21c and 21d. And the pressure difference between the 1st pressure receiving part 11c into which the pressure of the front | former stage side was introduce | transduced from the throttle parts 21c and 21d, and the 2nd pressure receiving part 11d to which the pressure of the back | latter stage side was introduce | transduced from the throttle parts 21c and 21d. The piston 12 moves so that the relationship between the spring force and the elastic force of the spring 13 is maintained constant.

  The piston 12 is positioned near one end portion on the first pressure receiving portion 11c side and positioned near the other end portion on the second pressure receiving portion 11d side and a first large diameter portion 12a that is in sliding contact with the casing 11. A second large-diameter portion 12b that is in sliding contact with the casing 11, and a small-diameter portion 12c that is positioned between the first large-diameter portion 12a and the second large-diameter portion 12b and is smaller than the large-diameter portion, Between the 1st large diameter part 12a and the small diameter part 12c, it is the structure which has the taper part 12d formed as a curved-surface-shaped part which diameter changes from the large diameter part 12a toward the small diameter part 12c.

  The piston 12 is slidably inserted into the casing 11, the hydraulic oil pressure introduced into the first pressure receiving portion 11 c, the hydraulic oil pressure introduced into the second pressure receiving portion 11 d, and the biasing force of the spring 13. It is the same as a known flow compensation valve with pressure compensation in that it moves based on the difference in force between the inlet portion 11a and the outlet portion 11b and adjusts the opening degree of communication between the inlet portion 11a and the outlet portion 11b. Detailed description is omitted.

  The piston 12 slides in the piston longitudinal direction with respect to the casing 11, and the first large-diameter portion 12 a approaches and slides against the narrow passage portion 11 f between the inlet portion 11 a and the outlet portion 11 b in the casing 11. This is a mechanism for reducing or increasing the opening degree of communication between the inlet portion 11a and the outlet portion 11b. The piston 12 receives a pressing force from the first pressure receiving portion 11c so as to reduce the opening degree of the communication between the inlet portion 11a and the outlet portion 11b, and the piston 12 is supplied from the second pressure receiving portion 11d and the spring 13. Thus, a pressing force is applied in a direction to increase the opening degree of communication between the inlet portion 11a and the outlet portion 11b.

The piston 12 is provided with two through holes (a first through hole 12e and a second through hole 12f) that are orthogonally communicated with each other at the center of the piston.
The first through hole 12e is formed in a predetermined range extending from the small diameter portion 12c and the first large diameter portion 12a with the taper portion 12d in the longitudinal direction of the piston 12 as a center, in a direction orthogonal to the longitudinal direction of the piston 12. Is done.

  The second through-hole 12f is another predetermined range that extends in the longitudinal direction of the piston 12 over the first large-diameter portion 12a and the tapered portion 12d and partially overlaps the predetermined range in which the first through-hole 12e exists. Are formed in a direction perpendicular to the longitudinal direction of the piston 12.

  The second through-hole 12f is biased toward the first large-diameter portion 12a so that the hole portion located in the first large-diameter portion 12a is larger than the hole portion located in the tapered portion 12d. And is positioned closer to one end of the piston 12 than the first through hole 12e. And the cross-sectional area of this 2nd through-hole 12f is made smaller than the cross-sectional area of the 1st through-hole 12e.

  Next, the movement state of the piston related to pressure compensation in the flow rate adjusting valve based on the above configuration will be described. As a premise, in the flow regulating valve 10, the biasing force of the spring 13 is appropriately set, and communication between the inlet portion 11 a and the outlet portion 11 b of the flow regulating valve 10 is allowed in the neutral state of the direction switching valve 20. It is assumed that it is in the state.

  Since the pressure port 23 of the direction switching valve 20 and the two load-side ports 26 and 27 communicating with the hydraulic motor-side circuit are not in communication with each other and the hydraulic oil is not supplied, the hydraulic motor 50 is stopped from a neutral state. The position of the spool 21 is switched by operation, the spool 21 is displaced in one direction (lower side in FIG. 1), the pressure port 23 communicates with one load side port 26, and the low pressure port 25 is on the other load side. When in communication with the port 27 (see FIG. 3), the high-pressure hydraulic oil from the pressure source 30 is directed through the flow regulating valve 10 in a state where communication between the inlet portion 11a and the outlet portion 11b is allowed. The process proceeds to the pressure port 23 of the switching valve 20, and further reaches the one load side port 26 through the throttle portion 21c. The hydraulic oil is supplied from the one load side port 16 to the hydraulic motor 50 through the one flow path 61 including the counter balance valve 65, so that the hydraulic motor 50 is driven in the forward rotation direction.

  In this state, the hydraulic oil pressure on the upstream side of the throttle portion 21c of the direction switching valve 20 is introduced into the first pressure receiving portion 11c of the flow rate adjusting valve 10 through the pressure port 23 and the outlet portion 11b, and the direction switching valve 20 The hydraulic oil pressure on the rear stage side of the throttle portion 21c is introduced into the second pressure receiving portion 11d through the one load side port 26 and the secondary pressure passage 11e. In the flow rate adjusting valve 10, the piston 12 moves so as to maintain a constant relationship between the pressure difference between the first pressure receiving portion 11c and the second pressure receiving portion 11d and the elastic force of the spring 13, and the inlet portion The communication opening degree between 11a and the exit part 11b is adjusted.

  Further, in the direction switching valve 20, when the position of the spool 21 is switched manually from the neutral state, the spool 21 is displaced in the other direction (upward in FIG. 1), and the pressure port 23 communicates with the other load side port 27. In the state where the low pressure port 24 communicates with one load side port 26 (see FIG. 3), the high pressure hydraulic oil from the pressure source 30 advances to the pressure port 23 of the direction switching valve 20 through the flow rate adjustment valve 10. It reaches the other load side port 27 through the throttle portion 21d. Then, the hydraulic oil output from the load side port 27 is supplied to the hydraulic motor 50 through the other flow path 62, so that the hydraulic motor 50 is driven in the reverse rotation direction.

  In this state, the hydraulic oil pressure on the upstream side of the throttle portion 21d of the direction switching valve 20 is introduced into the first pressure receiving portion 11c of the flow rate adjusting valve 10 through the pressure port 23 and the outlet portion 11b, and the direction switching valve 20 The hydraulic oil pressure on the rear stage side of the throttle portion 21d is introduced into the second pressure receiving portion 11d through the other load side port 27 and the secondary pressure passage 11e. In the flow rate adjusting valve 10, as in the case of the forward rotation of the hydraulic motor 50, the relationship between the pressure difference between the first pressure receiving portion 11 c and the second pressure receiving portion 11 d and the elastic force of the spring 13 is kept constant. The piston 12 moves so as to adjust the opening degree of communication between the inlet portion 11a and the outlet portion 11b.

  In the flow rate adjusting valve 10, the hydraulic oil that has flowed into the inlet portion 11a in a state where communication between the inlet portion 11a and the outlet portion 11b is allowed is around the tapered portion 12d of the piston 12 facing the inlet portion 11a. And the outlet portion 11b through the gap portion around the small diameter portion 12c (see FIG. 5).

  If the load of the hydraulic motor 50 increases and the pressure of the hydraulic oil in the flow path on the supply side to the hydraulic motor 50 suddenly increases, the downstream side of the throttle portion communicating with the pressure port 23 of the direction switching valve 20 The hydraulic oil pressure also increases with respect to the hydraulic oil pressure on the upstream side of the throttle portion. The force that pushes the other end of the piston 12 with the hydraulic oil pressure introduced into the second pressure receiving portion 11d and the elastic force of the spring 13 is the hydraulic oil pressure introduced into the first pressure receiving portion 11c. The piston 12 moves in a direction (left side in FIG. 5) in which the opening degree of communication between the inlet portion 11a and the outlet portion 11b is increased by exceeding the force pushing the portion. Specifically, the piston 12 moves so as to separate the first large-diameter portion 12a with respect to the narrow passage portion 11f between the inlet portion 11a and the outlet portion 11b in the casing 11, and accordingly, The gap portion around the tapered portion 12d is increased, and the opening degree of communication between the inlet portion 11a and the outlet portion 11b is increased (see FIG. 6).

  In this way, the opening degree of communication between the inlet portion 11a and the outlet portion 11b is increased by the piston 12, so that the pressure loss related to the flow between the inlet portion 11a and the outlet portion 11b of the flow rate adjusting valve 10 is reduced, and the outlet portion 11b and The pressure of the hydraulic oil reaching the pressure port 23 can be increased, and the force pushing the one end of the piston 12 with the hydraulic oil pressure introduced into the first pressure receiving portion 11c also increases. Eventually, the force that pushes the other end of the piston 12 and the force that pushes the one end of the piston 12 are balanced and the piston 12 stops, and the pressure difference between the front side and the rear side of the throttle part is kept constant. As a result, the flow rate of the hydraulic oil flowing from the flow rate adjusting valve 10 to the direction switching valve 20 can be made constant, whereby the flow rate of the hydraulic oil supplied to the hydraulic motor 50 through the direction switching valve 20 is constant regardless of the load increase. It can be.

  On the other hand, when the pressure of the hydraulic oil flowing into the inlet portion 11a of the flow rate adjusting valve 10 becomes relatively large, such as when the load of the hydraulic motor 50 is suddenly reduced or when the hydraulic motor 50 is started, the flow rate adjusting valve 10 The hydraulic fluid pressure on the upstream side of the throttle portion of the direction switching valve 20 communicating with the outlet portion 11b of the directional control valve 20 increases relative to the hydraulic oil pressure on the downstream side of the throttle portion. Contrary to the case of the load increase described above, the force pushing the one end of the piston 12 with the hydraulic pressure introduced into the first pressure receiving portion 11c is the hydraulic pressure introduced into the second pressure receiving portion 11d. The direction in which the piston 12 decreases the opening degree of communication between the inlet portion 11a and the outlet portion 11b by exceeding the force pushing the other end of the piston 12 with the elastic force of the spring 13 (right side in FIG. 5). Move to. Specifically, the piston 12 moves so that the first large-diameter portion 12a approaches the narrow passage portion 11f between the inlet portion 11a and the outlet portion 11b in the casing 11, and accordingly, The gap portion around the tapered portion 12d is reduced, and the opening degree of communication between the inlet portion 11a and the outlet portion 11b is reduced.

  Thus, by reducing the opening of the communication between the inlet portion 11a and the outlet portion 11b with the piston 12, the pressure loss related to the flow between the inlet portion 11a and the outlet portion 11b of the flow rate adjusting valve 10 is increased, and the outlet portion 11b and The pressure of the hydraulic oil reaching the pressure port 23 can be reduced, and the force pushing the one end of the piston 12 with the hydraulic oil pressure introduced into the first pressure receiving portion 11c is also reduced. Eventually, the force that pushes the other end of the piston 12 and the force that pushes the one end of the piston 12 are balanced and the piston 12 stops, and the pressure difference between the front side and the rear side of the throttle part is kept constant. Thus, the flow rate of the hydraulic oil flowing into the direction switching valve 20 from the flow rate adjusting valve 10 can be made constant, and thereby the flow rate of the hydraulic oil supplied to the hydraulic motor 50 through the direction switching valve 20 can be made constant. .

  In addition, when the hydraulic motor 50 is started up, the pressure of the hydraulic oil flowing into the inlet portion 11a of the flow rate adjusting valve 10 increases rapidly, and the hydraulic oil pressure on the front side of the throttle portion becomes larger than the hydraulic oil pressure on the rear side. When the force that pushes one end of the piston 12 in the first pressure receiving portion 11c greatly exceeds the force that pushes the other end of the piston 12 in the second pressure receiving portion 11d, the piston 12 is connected to the inlet portion 11a. It will be in the state which is going to close the flow path between the exit parts 11b.

  In this case, the piston 12 causes the first large-diameter portion 12a to approach the narrow passage portion 11f between the inlet portion 11a and the outlet portion 11b in the casing 11, and further, the casing inner peripheral surface forming the passage portion 11f. The first large diameter portion 12a is moved so as to be in sliding contact with the first large diameter portion 12a.

  In this process, until the boundary between the first large-diameter portion 12a of the piston 12 and the tapered portion 12d reaches the end of the inlet portion 11a, the hydraulic oil surrounds the tapered portion 12d of the piston 12 facing the inlet portion 11a. In the flow state that reaches the outlet portion 11b through the gap portion and the gap portion around the small diameter portion 12c, the boundary portion of the piston 12 reaches the end of the inlet portion 11a, and the first large diameter portion 12a is the passage portion. When it comes into sliding contact with the inner peripheral surface of the casing forming 11f (see FIGS. 7 and 8), the second through hole 12f of the first large-diameter portion 12a facing the inlet portion 11a, the tapered portion 12d, and the small-diameter portion 12c. And the first through hole 12e facing the gap between the casing 11 and the casing 11 will shift to a state in which hydraulic oil flows from the inlet portion 11a to the outlet portion 11b.

  However, even when the first large-diameter portion 12a is in sliding contact with the inner peripheral surface of the casing forming the passage portion 11f, the first through-hole 12e and the second through-hole 12f are in contact with the inlet portion 11a. Part of the hydraulic oil can flow from the inlet portion 11a to the outlet portion 11b through a slight gap portion generated in the vicinity of the casing 11 by the opening portions of the one through hole 12e and the second through hole 12f. .

  Eventually, as the second through hole 12f reaches a position where it does not face the inlet portion 11a due to the movement of the piston 12, the inlet portion 11a and the outlet portion 11b are not in communication at all and no hydraulic oil flows. (See FIG. 11).

  The state in which the hydraulic fluid flows through the second through hole 12f and the first through hole 12e immediately before the opening degree of communication between the inlet portion 11a and the outlet portion 11b is set to 0 by the piston 12 is the second through hole. Since 12f continues while facing the inlet portion 11a (see FIGS. 7 to 10), the direction in which the hydraulic oil flows from the inlet portion 11a to the outlet portion 11b immediately before the flow path is closed is almost equal to that of the hydraulic oil. Is different from the moving direction of the piston 12. Accordingly, the behavior of the piston 12 is less affected by the flow of the hydraulic oil, and the piston 12 can be moved so that the pressure compensation is correctly executed. The original adjustment function that keeps the flow rate of the gas constant can be demonstrated correctly. In addition, the unstable behavior of the piston 12 can be suppressed, and a sudden change in the hydraulic oil pressure leading to an abnormality such as hunting on the rear stage side can be prevented, and the stability of the hydraulic circuit can be improved.

  Further, the second through hole 12f in the piston 12 is made smaller than the first through hole 12e, and the piston 12 faces the inlet portion 11a in a state of closing the gap between the inlet portion 11a and the outlet portion 11b. While the hydraulic oil is directed from the second through hole 12f to the outlet portion 11b through the first through hole 12e, the second through hole 12f acts as a throttle on the hydraulic oil to reduce the pressure of the hydraulic oil. Thus, the pressure of the hydraulic oil reaching the outlet portion 11b through the second through hole 12f and the first through hole 12e is set to an appropriate magnitude, and the flow of the hydraulic oil on the outlet portion 11b side is maintained in a stable state. In addition, it is possible to restrict the flow of the hydraulic oil with the throttle in the second through-hole 12f, and to suppress the hydraulic oil from reaching the outlet portion 11b excessively and causing a sudden change in the flow. Evil such as hunting It is possible to more reliably prevent the sound.

  In addition, the second through-hole 12f has a hole portion provided in the first large-diameter portion 12a larger than the hole portion provided in the tapered portion 12d and is biased toward the first large-diameter portion 12a. Thus, the hole portion appearing in the taper portion 12d is minimized. Thereby, in a state where the boundary portion between the first large diameter portion 12a and the taper portion 12d of the piston 12 reaches the end of the inlet portion 11a, a part of the hydraulic oil is formed in the opening portion of the second through hole 12f. After entering from the region on the first large-diameter portion side of the second through-hole 12f, it exits from the region on the tapered portion side and proceeds through the gap portion between the small-diameter portion 12c and the casing 11 to the outlet portion 11b. Although the flow to reach, that is, the flow in the same direction as the movement direction of the piston 12 may occur, the flow rate of the hydraulic oil flowing in the same direction as the piston movement direction is changed to the second through hole 12f and the first through hole 12e. The flow rate of the hydraulic oil flowing toward the outlet portion 11b is limited to a small percentage so that the flow of the hydraulic oil in the same direction as the piston movement direction hardly affects the piston 12. That.

  Further, the first through hole 12e and the second through hole 12f in the piston 12 are positioned so as to be orthogonal to each other, and the opening portion of the first through hole 12e and the opening portion of the second through hole 12f are defined on the piston surface. When the piston 12 tries to close the space between the inlet portion 11a and the outlet portion 11b by separating them as much as possible, the flow of the hydraulic oil in the inlet portion 11a into the second through hole 12f and the hydraulic oil The flow from the first through hole 12e toward the outlet 11b does not affect each other, and the hydraulic oil flows into the second through hole 12f and flows out from the first through hole 12e. Can be made smooth to make it difficult for abnormalities such as sudden changes in pressure to occur, and the flow of hydraulic oil can be prevented from affecting the behavior of the piston 12.

  A state in which the second through-hole 12f does not face the inlet portion 11a as the piston 12 further moves after the first large diameter portion 12a of the piston 12 comes into sliding contact with the casing inner peripheral surface forming the passage portion. Thus, when the communication between the inlet portion 11a and the outlet portion 11b is cut off, the flow of hydraulic oil from the inlet portion 11a to the outlet portion 11b is stopped (see FIG. 11).

  By eliminating the flow of the hydraulic oil to the outlet portion 11b in this way, the force pushing the one end portion of the piston 12 in the first pressure receiving portion 11c leading to the outlet portion 11b is also reduced, and this force is reduced in the second pressure receiving portion 11d. 12 The force pushing the other end is relatively higher. As a result, the piston 12 again moves in a direction (left side in FIG. 5) that increases the degree of communication between the inlet portion 11a and the outlet portion 11b, and is narrow between the inlet portion 11a and the outlet portion 11b in the casing 11. The first large-diameter portion 12a is separated from the passage portion, and communication between the inlet portion 11a and the outlet portion 11b is resumed.

  Thereafter, as described above, the force that pushes the other end of the piston 12 and the force that pushes the one end of the piston 12 are balanced, and the piston 12 stops, and the pressure difference between the front side and the rear side of the throttle portion is constant. By maintaining the flow rate at a constant value, the flow rate of the hydraulic oil flowing from the flow rate adjusting valve 10 into the direction switching valve 20 can be made constant, and at the same time, the flow rate of the hydraulic oil supplied to the hydraulic motor 50 can be made constant.

  As described above, in the flow rate adjusting valve according to the present embodiment, the piston 12 disposed in the casing 11 so that the opening degree of the communication between the inlet portion 11a and the outlet portion 11b can be adjusted has two large diameter portions 12a and 12b. And a small-diameter portion 12c and a tapered portion 12d sandwiched between them, a first through-hole 12e is provided in a predetermined range around the tapered portion 12d of the piston 12, and the first large-diameter The second through hole 12f is provided in another predetermined range centered on the portion 12a, and the second through hole 12f closer to one end of the piston than the first through hole 12e intersects the first through hole 12e. The second through hole 12f facing the inlet portion 11a, the small diameter portion 12c, and the tapered portion 12d in a state where the piston 12 tries to close the flow path between the inlet portion 11a and the outlet portion 11b. And casing 11 The hydraulic fluid can flow from the inlet portion 11a to the outlet portion 11b through the first through hole 12e facing the gap between the second through hole 12f and the inlet portion 11a. Since the operation oil flows from the inlet portion 11a to the outlet portion 11b immediately before closing, the direction in which the hydraulic oil flows is different from the moving direction of the piston 12, and the behavior of the piston 12 is affected by the flow of the hydraulic oil. The piston 12 can be moved so that the pressure compensation can be correctly executed, and the original adjustment function for making the flow rate of the hydraulic oil constant regardless of the change of the hydraulic oil pressure due to the load fluctuation can be exhibited correctly. The unstable behavior of the hydraulic fluid can be suppressed, a sudden change in hydraulic oil pressure can be prevented, and the stability of the hydraulic circuit can be improved.

  Further, only by providing two through holes at predetermined positions of the piston 12, the inlet 12a and the outlet 11b in a state where the piston 12 attempts to close the flow path between the inlet 11a and the outlet 11b, Therefore, it is possible to form an appropriate passage through which the hydraulic oil flows, and to easily obtain a valve device having optimum characteristics.

DESCRIPTION OF SYMBOLS 10 Flow control valve 11 Casing 11a Inlet part 11b Outlet part 11c First pressure receiving part 11d Second pressure receiving part 11e Secondary pressure passage 11f Passage part 12 Piston 12a First large diameter part 12b Second large diameter part 12c Small diameter Part 12d taper part 12e first through hole 12f second through hole 13 spring 20 direction switching valve 21 spool 21c, 21d throttle part 23 pressure port 24, 25 low pressure port 26, 27 load side port 30 pressure source 40 low pressure part 50 Hydraulic motor 61, 62 Flow path 65 Counter balance valve 90 Valve device

Claims (4)

A casing having a fluid inlet and outlet, and a piston that is slidably inserted into the casing and adjusts the degree of communication between the inlet and outlet, and the casing includes the piston. A first pressure receiving portion facing one end portion and a second pressure receiving portion facing the other end portion of the piston are provided, and the fluid pressure on the front stage side in the throttle mechanism leading to the outlet portion of the casing is supplied to the first pressure receiving portion. In addition to introducing the fluid pressure on the rear stage side of the throttle mechanism into the second pressure receiving portion, the piston is moved based on the pressure difference before and after the throttle mechanism, and the opening degree of communication between the inlet portion and the outlet portion In the flow control valve with pressure compensation to adjust
The piston is located on one end side and faces the inlet portion and slidably contacts the casing, and the second large diameter portion is located near the other end and slidably contacts the casing; It is located in the middle between the first large diameter part and the second large diameter part and is smaller than the large diameter part, and has a small diameter part facing the outlet part, from the first pressure receiving part Direction to reduce the opening degree of communication between the inlet part and the outlet part with the piston and to increase the opening degree of communication between the inlet part and the outlet part with the piston from the second pressure receiving part It is arranged to receive a pressing force,
Between the first large-diameter portion and the small-diameter portion of the piston, a curved taper portion whose diameter changes in a tapered manner from the large-diameter portion to the small-diameter portion is formed,
A first through hole is formed in at least the tapered portion of the piston in a direction orthogonal to the longitudinal direction of the piston,
A second through hole is formed in at least the first large diameter portion of the piston in a direction perpendicular to the longitudinal direction of the piston and closer to one end of the piston than the first through hole,
The flow rate regulating valve, wherein the second through hole crosses and communicates with a part of the first through hole. In the flow regulating valve according to claim 1,
The flow regulating valve, wherein a cross-sectional area of the second through hole in the piston is smaller than a cross-sectional area of the first through hole. In the flow regulating valve according to claim 1 or 2,
The second through hole in the piston is arranged over the first large diameter portion and the tapered portion, and the hole portion located in the first large diameter portion of the holes is more than the hole portion located in the tapered portion. A flow regulating valve characterized in that the flow regulating valve is formed to be biased toward the first large-diameter portion so as to be enlarged. In the flow regulating valve according to any one of claims 1 to 3,
The flow rate adjusting valve, wherein the first through hole and the second through hole in the piston are formed so as to be orthogonal to each other.

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