JP6119875B2 - Flow control valve - Google Patents

Description

  The present invention relates to a flow control valve used in a hydraulic device such as a forklift.

  Conventionally, in a hydraulic circuit used for a forklift, in order to suppress the descending speed when the lift is lowered, the flow rate between a cylinder port connected to the hydraulic cylinder of the forklift and a tank for storing hydraulic fluid The structure which provides a control valve is known (for example, refer to patent documents 1).

  As an example of such a flow control valve, there is a configuration including a body and a spool that divides the inside of the body into a control chamber and a damper chamber and is slidable inside the body. More specifically, the body includes a variable throttle opening on the cylinder side and a control throttle opening on the tank side. On the other hand, by sliding the inside of the body, the spool can change between an initial state in which the entire variable throttle is communicated and a control state in which only a part of the variable throttle is in communication. The spool is biased to the initial state side by a first coil spring that is a main biasing means disposed in the damper chamber of the body.

  Here, when the spool is changed from the initial state to the control state as the hydraulic pressure of the hydraulic fluid introduced from the cylinder side into the control chamber increases, the damper chamber promptly moves from the damper chamber to the control chamber. It is required that the working fluid be circulated in the tank. On the other hand, hunting may occur when the working fluid is quickly circulated from the control chamber to the damper chamber when the control state is shifted to the initial state, that is, when the spool is quickly moved.

  Therefore, when the spool transitions from the initial state to the control state, the valve is opened to permit the flow of hydraulic fluid between the inside and outside of the damper chamber, and when the spool transitions from the control state to the initial state. Is considered to be provided with a check valve that closes and shuts off the inside and outside of the damper chamber. Such a check valve includes a valve body disposed in the damper chamber, a seal member having a valve seat that is also disposed in the damper chamber and on which the valve body can be seated, and a valve member disposed in a spring chamber. And a second coil spring that is sub-biasing means that urges the valve seat in the direction of seating.

  When such a configuration is adopted, the hydraulic fluid in the damper chamber is quickly discharged by opening the check valve, so that the spool can be quickly moved and the responsiveness is high. On the other hand, when the control state is shifted to the initial state, the check valve is closed and the flow rate of the hydraulic fluid into the damper chamber is suppressed, so that the moving speed of the spool is reduced and hunting occurs. It is suppressed.

JP 2000-255998 A

  However, when high-pressure hydraulic fluid is rapidly introduced from the cylinder side through the control chamber into the damper chamber, such as when a large amount of luggage is loaded on the loading platform, the check valve body and valve seat are opened. The provided seal member moves in a direction away from the control chamber against the elastic biasing force of the first coil spring. At this time, the second coil spring that urges the valve body toward the valve seat may also jump out of the spring chamber that houses the auxiliary urging means.

  Thereafter, when the hydraulic pressure of the hydraulic fluid introduced from the cylinder side decreases, the valve body and the seal member move in a direction approaching the control chamber, that is, a direction approaching the spring chamber, by the elastic biasing force of the first coil spring. When the second coil spring protrudes from the spring chamber, there is a problem in that the second coil spring may be sandwiched between the valve body or the seal member and the spool to be deformed and may not be used.

  As a method for suppressing the occurrence of such a problem, a mode is adopted in which the outer diameter of the second coil spring is slightly larger than the inner diameter of the spring chamber and the second coil spring is press-fitted into the spring chamber. It is possible. However, in this aspect, if the outer diameter of the second coil spring becomes too large, it becomes impossible to press-fit into the spring chamber. Conversely, if the outer diameter of the second coil spring becomes smaller, the second coil spring becomes smaller. There is a problem in that the friction generated between the spring and the spring chamber is not sufficient, and the second coil spring cannot be sufficiently suppressed. Therefore, high processing accuracy is required in forming the spring chamber and manufacturing the second coil spring, leading to an increase in manufacturing cost. Furthermore, the process of press-fitting the second coil spring into the spring chamber is increased.

  The present invention pays attention to the above points, while reducing labor during manufacture, and the auxiliary biasing means (second coil spring) of the check valve when high-pressure hydraulic fluid is rapidly introduced from the cylinder side. ) To prevent damage.

  In order to solve the above problems, the flow control valve according to the present invention has a configuration as described below. That is, a flow control valve according to the present invention includes a body having a variable throttle that opens on a cylinder side and a control throttle that opens on a discharge port side, and a control chamber and a damper that communicate the interior of the body with the variable throttle and the control throttle. A spool that can be changed between an initial state in which the whole of the variable throttle is communicated and a control state in which only a part of the variable throttle is communicated by partitioning into the chamber and sliding inside the body; A main urging means for urging the spool toward the initial state and being opened when the spool transitions from the initial state to the control state, between the inside and the outside of the damper chamber. A flow control valve that includes a check valve that permits the flow of the hydraulic fluid and closes when the spool transitions from the control state to the initial state, and shuts off the inside and the outside of the damper chamber. Thus, the check valve is disposed in a check valve storage space formed in the spool and has a seal member, a valve body that can be seated on the valve seat of the seal member, and the check valve A sub-urging means arranged in a spring chamber communicating with the storage space and urging the valve body in a direction of seating on the valve seat; and the valve of the seal member is disposed in the check valve storage space of the spool. Protrusions that allow movement in the direction approaching the body and the sub-biasing means and restrict movement in the opposite direction are provided.

  In such a case, even when high-pressure hydraulic fluid is rapidly introduced from the cylinder side, the movement of the seal member in the direction away from the valve body and the auxiliary biasing means is restricted by the projection. Therefore, the auxiliary biasing means is also restricted from jumping out of the spring chamber by this seal member, and is held in the spring chamber. In addition, since the seal member is allowed to move over the protrusion and move toward the valve body and the auxiliary biasing means, when the seal member is assembled in the spool, it is pushed over the protrusion and press-fitted. The flow rate control valve having a configuration capable of obtaining the above-described effects can be realized with less assembly work.

  ADVANTAGE OF THE INVENTION According to this invention, damage to the auxiliary | assistant biasing means of a non-return valve at the time of a high pressure working fluid being rapidly introduced from the cylinder side can be suppressed, aiming at reduction of the effort at the time of manufacture.

Schematic which shows the hydraulic circuit which concerns on one Embodiment of this invention. Schematic which shows the flow control valve concerning the embodiment. The enlarged view of the principal part in FIG. Action | operation explanatory drawing of the flow control valve which concerns on the same embodiment.

  As shown in FIG. 1, the fluid control valve constituting the hydraulic circuit of the present embodiment operates on a suction port 3 for sucking hydraulic fluid supplied from a hydraulic pressure supply source such as a pump (not shown) and a tank (not shown). A sleeve 5 to which a discharge port 4 for discharging liquid is connected, an intermediate chamber 6 that communicates with the sleeve 5 and a flow control valve 11 of the present invention is disposed, communicates with the intermediate chamber 6 and sends hydraulic fluid to the lift cylinder C. Cylinder port 7, a lift lock poppet 8 provided between these intermediate chamber 6 and cylinder port 7, which opens and closes a flow path between them and has a back pressure chamber 8 a inside, and a back pressure chamber of this lift lock poppet 8 A pilot passage 9 connecting 8a and the intermediate chamber 6, and an electromagnetic solenoid valve 10 provided in the pilot passage 9 for permitting or blocking the flow of hydraulic fluid in the pilot passage 9. The valve body 1 provided in the section, the ascending position which is incorporated in the sleeve 5 so as to be able to advance and retract, and which connects the cylinder port 7 and the suction port 3 to form the flow path of the hydraulic fluid, the cylinder port 7 and the discharge port 4 And a main spool 2 capable of selectively taking a lowered position for forming a flow path for hydraulic fluid by communicating with each other and a neutral position for blocking the flow path between these ports.

  Here, when the main spool 2 moves from the neutral position in the direction of the arrow X in FIG. 1 and reaches the lowered position, hydraulic fluid flows from the back pressure chamber 8a of the lift lock poppet 8 into the intermediate chamber 6 and the discharge port. 4, the hydraulic fluid pressure guided from the lift cylinder C to the cylinder port 7 becomes higher than the hydraulic fluid pressure in the back pressure chamber 8 a, and the lift lock poppet 8 is opened by this differential pressure. . Then, the hydraulic fluid passes through the flow rate control valve 11 disposed in the intermediate port 6 of the cylinder port 7 and is guided to the tank through the discharge port 4.

  Here, the intermediate chamber 6 includes a high-pressure chamber 6 a that communicates with the cylinder port 7 and a low-pressure chamber 6 b that communicates with the discharge port 4. The flow control valve 11 is disposed so as to straddle the high pressure chamber 6a and the low pressure chamber 6b, and controls the flow rate of the working fluid from the high pressure chamber 6a to the low pressure chamber 6b.

  More specifically, as shown in FIG. 2, the flow control valve 11 includes a body 21 having a variable throttle 24 that opens to the high-pressure chamber 6a and a control throttle 25 that opens to the low-pressure chamber 6b. The initial state S in which the whole of the variable throttle 24 is communicated with the variable throttle 24 by sliding the inside of the body 21 while partitioning the inside into the valve chamber 26 and the damper chamber 27 communicating with the variable throttle 24 and the control throttle 25 and the variable throttle. A control spool 22 that can change between a control state C in which only a part of 24 is communicated and a main spool that is arranged inside the damper chamber 27 of the body 21 and biases the control spool 22 toward the initial state S. When the first coil spring 23, which is a biasing means, and the control spool 22 shift from the initial state S to the control state C, the valve opens and the flow of hydraulic fluid between the inside and the outside of the damper chamber 27 occurs. When the control spool 22 is allowed to shift to the initial state S from the control state C to have a check valve 28 for blocking between the inside and outside of the damper chamber 27 is closed. The control spool 22 is a spool of the flow control valve 11 of the present invention.

  More specifically, the body 21 is fixed to the valve body 1 of the fluid control valve and communicates with the variable throttle 24, the control throttle 25 and the discharge port 4 as shown in FIGS. 1, 2 and 4. A drain hole 29 is opened. The high pressure chamber 6a and the low pressure chamber 6b are partitioned by the body 21.

  2 and 4, the control spool 22 has a groove for forming a valve chamber 26 for communicating the variable throttle 24 and the control throttle 25, and in the initial state S. The drain hole 29 is closed. Further, when the amount of hydraulic fluid flowing from the variable throttle 24 increases, the hydraulic fluid pressure in the valve chamber 26 becomes higher than the damper chamber 27 communicating with the low pressure chamber 6b, so that the control spool 22 slides in the body 21. 2 shifts from the initial state shown in FIG. 2 to the control state C shown in FIG. The control spool 22 in the control state C closes a part of the variable throttle 24. That is, the control spool 22 and the variable throttle 24 function together as a throttle for controlling the flow rate of the working fluid from the high pressure chamber 6a to the low pressure chamber 6b. A lower pressure side of the space in the body 21 than the control spool 22 is partitioned as a damper chamber 27. The working fluid flows between the valve chamber 26 and the damper chamber 27 through a gap between the body 21 and the control spool 22. In addition, a check valve storage space 22 s for storing the check valve 28 is formed in a portion of the control spool 22 on the damper chamber 27 side. The control spool 22 is also provided with a communication hole 22h that communicates the inside and the outside of the check valve storage space 22s.

  2 and 4, the first coil spring 23 is disposed inside the damper chamber 27 of the body 21 as described above, and is connected to the control spool 22 via a seal member 29 described later of the check valve 28. Is a coil spring that is elastically biased toward the initial state S side.

  2 and 4, the check valve 28 is disposed in a check valve storage space 22s of the control spool 22, and includes a seal member 29 having a check valve seat 29a, and the check valve storage. A check valve body 30 disposed in the space 22s and seatable on the check valve seat 29a, and a spring chamber 22r communicating with the check valve storage space 22s is disposed in the check valve body 30. And a second coil spring 31 which is sub-bias means for urging the seat to be seated on the stop valve seat 29a.

  The seal member 29 is slidable in the check valve storage space 22s. The seal member 29 is in contact with the free end of the first coil spring 23 at the end face on the damper chamber 27 side and receives an elastic biasing force, and is in contact with the control spool 22 at the opposite end face to control the elastic biasing force. 22 is transmitted. The seal member 29 is formed with a valve body storage space 29s having a check valve seat 29a, and a passage 29x that connects the inside and the outside of the valve body storage space 29s.

  When the control spool 22 shifts from the initial state S to the control state C, the check valve body 30 takes the valve opening position Q spaced from the check valve seat 29a and opens the check valve 28. The flow of hydraulic fluid from the damper chamber 27 to the valve chamber 26 through the valve body storage space 29s and the passage 29x is permitted, and when the control spool 22 shifts from the control state C to the initial state S, the check valve seat The check valve 28 is closed by taking the valve closing position P seated on 29a, and the flow of hydraulic fluid through the passage 29x and the valve body storage space 29s is cut off.

  In this embodiment, as shown in FIG. 3, the movement of the seal member 29 in the direction approaching the spring chamber 22r is permitted in the check valve storage space 22s of the control spool 22, and the movement in the opposite direction is permitted. A protrusion 22t for restricting the movement is provided.

  The surface of the protrusion 22t toward the damper chamber 27 is an inclined surface 22t1 having an inclination in which the protrusion width increases as the distance from the damper chamber 27 increases. On the other hand, the surface of the projection 22t facing the spring chamber 22r is a standing surface 22t2 that stands up from the inner surface of the control spool 22 at a substantially right angle. In FIG. 3, the protrusion width is drawn larger than the actual width so that the presence of the protrusion 22t can be easily understood, but the protrusion width of the protrusion 22t is set to 0.01 to 0.1 mm, for example.

  An example of the procedure for assembling the check valve 28 to the control spool 22 will be described below. First, the second coil spring 31 is accommodated in the spring chamber 22r. Next, the check valve body 30 is disposed so as to contact the free end of the second coil spring 31. Then, the seal member 29 is inserted into the check valve storage space 22s of the control spool 22, and is further press-fitted into the interior while getting over the inclined surface 22t1 of the protrusion 22t.

  Here, the operation of each part of the flow control valve 11 when the main spool 2 of the fluid control valve takes the lowered position will be described.

  When no load is loaded on the lift, the pressure applied to the cylinder port 7 is low, and the amount of liquid passing through the control throttle 25 is small. Therefore, the hydraulic fluid pressure difference between the valve chamber 26 and the damper chamber 27 is small, and the control spool 22 is maintained in the initial state S shown in FIG. That is, the entire variable throttle 24 communicates with the valve chamber 26, and the working fluid is guided from the high pressure chamber 6 a to the low pressure chamber 6 b through the variable throttle 24, the valve chamber 26 and the control throttle 25 as indicated by an arrow Y in FIG. .

  After that, when the load is loaded on the lift, that is, when the lift is lowered again in the load state, the hydraulic fluid pressure applied to the cylinder port 7 is increased, so that the amount of fluid passing through the control throttle 25 is also increased. . However, since the pressure difference between the valve chamber 26 and the damper chamber 27 also increases due to the flow rate, the control spool 22 moves so as to overcome the urging force of the first coil spring 23 and enter the control state C as shown in FIG. . At this time, a part of the variable throttle 24 is closed by the control spool 22, and an increase in the amount of liquid introduced into the valve chamber 26 is suppressed. The seal member 29 of the check valve 28 moves integrally with the control spool 22, while the check valve body 30 of the check valve 28 does not move until it hits the control spool 22 and takes the valve opening position Q. .

  Here, when high-pressure hydraulic fluid is rapidly introduced into the cylinder port 7, the hydraulic fluid flows into the valve body storage space 29s through the valve chamber 26 as shown by the arrow A in FIG. As a result, the seal member 29 receives an action in the control spool 22 in a direction away from the spring chamber 22r. However, the seal member 29 hits the rising surface 22t2 of the projection 22t, and further movement is restricted. Since the check valve body 30 is in the valve opening position Q, a part of the hydraulic fluid in the damper chamber 27 is not only in the gap between the control spool 22 and the body 21 but also in the valve body storage space 29s. Is introduced into the valve chamber 26. Further, another part of the hydraulic fluid in the damper chamber 27 is discharged from the damper chamber 27 to the discharge port 4 through the low pressure chamber 6b as shown by an arrow B in FIG.

  Further, when the lift is lowered again with the lift luggage removed, the hydraulic fluid pressure introduced into the cylinder port 7 is lowered and the amount of fluid passing through the control throttle 25 is small. Therefore, the hydraulic pressure difference between the valve chamber 26 and the damper chamber 27 is also reduced, so that the control spool 22 is moved to the initial state S by the urging force of the first coil spring 23. At this time, the seal member 29 also moves so as to be in the initial state S, and takes the valve closing position P where the check valve body 30 is seated on the check valve seat 29a as shown in FIG.

  As described above, according to the present embodiment, even when high-pressure hydraulic fluid is rapidly introduced from the cylinder side, the seal member 29 is moved away from the valve chamber 26 by the protrusion 22t. Therefore, the seal member 29 also restricts the second coil spring 31 from jumping out of the spring chamber 22r and is held in the spring chamber 22r. In addition, since the seal member 29 is allowed to move over the projection 22t and approach the valve chamber 26, when the seal member 29 is assembled in the control spool 22, the seal member 29 must be over the projection 22t. What is necessary is just to press-fit, and the flow control valve of the structure which can obtain the effect mentioned above can be implement | achieved by the effort of a small assembly.

  The present invention is not limited to the embodiment described above.

  For example, the shape of the protrusion may be arbitrarily set as long as it allows movement of the seal member from the damper chamber side to the spring chamber side and restricts movement in the opposite direction.

  In addition, the shapes of the valve body and the valve seat of the check valve may be arbitrarily set.

  In addition, various changes may be made without departing from the spirit of the present invention.

  According to the present invention, in a flow control valve used in a hydraulic device such as a forklift, the check valve when a high-pressure hydraulic fluid is rapidly introduced from the cylinder side while reducing labor during manufacture is provided. Damage to the auxiliary biasing means can be suppressed.

11 ... Flow control valve 21 ... Body 22 ... Spool (control spool)
22t ... projection 23 ... main biasing means (first coil spring)
24 ... Variable throttle 25 ... Control throttle 26 ... Valve chamber 27 ... Damper chamber 28 ... Check valve 29 ... Seal member 29a ... Valve seat 30 ... Valve body 31 ... Sub biasing means (second coil spring)

Claims (1)

A body having a variable throttle opening on the cylinder side and a control throttle opening on the discharge port side, and the inside of the body is divided into a control chamber and a damper chamber communicating with the variable throttle and the control throttle, and the inside of the body is slid A spool capable of changing between an initial state in which the entire variable throttle is communicated and a control state in which only a part of the variable throttle is communicated, and the spool disposed in a damper chamber of the body. When the main urging means for urging to the initial state side and the spool shift from the initial state to the control state, the valve is opened to permit the flow of hydraulic fluid between the inside and the outside of the damper chamber, and the spool A flow control valve comprising a check valve that closes and shuts off between the inside and the outside of the damper chamber when transitioning from the control state to the initial state,
The check valve is disposed in a check valve storage space formed in the spool and has a seal member having a valve seat, a valve body seatable on the valve seat of the seal member, and the check valve storage space A secondary biasing means that is arranged in a communicating spring chamber and biases the valve body in a direction of seating on the valve seat;
In the check valve storage space of the spool, there is provided a protrusion that allows the seal member to move in a direction approaching the valve body and the sub-bias means and restricts the movement in the reverse direction. Flow control valve to do.

Images