JP2009133367A - Flow control valve, directional control valve unit, and hydraulic circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reliably improve response of a flow control spool without bringing about its inadvertent performance. <P>SOLUTION: A pressure chamber 33 is built in a retainer part 30M of a flow control spool 30 and pilot oil passages 33, 35 which implement pilot pressures after passing an aperture 40 are built in the pressure chamber 33, and a spool spring 34 which presses the flow control spool 30 to the other end part side is accommodated in the pilot case 31. An aperture oil passage 50 is provided in the region constantly communicating the pressure chamber part 33 and the pilot passages 33, 35 in the retainer part 30M and notched parts 61 are provided in the region where the retainer part 30M and the inner wall side of the pilot case 31 are abraded, thereby a liaison oil passage 60 bigger than the aperture oil passage 50 of the opening area is provided, and in the territory in which the opening area changes with a meandering point X between the input port 15 and the output port 16 by the operation of the flow control spool 30, the liaison oil passage 60 is closed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a flow control valve, a direction control valve unit, and a hydraulic circuit.

  As a flow control valve for controlling the flow rate of oil passing by applying a pilot pressure to the end of the flow control spool disposed in the valve body and operating the flow control spool in accordance with the change in the pilot pressure, For example, there is one described in Patent Document 1.

  In this flow control valve, a communication oil passage having a damping orifice and a check valve is provided in parallel between a pressure chamber provided in the pilot case and a cushion chamber in which an end of the flow control spool is accommodated. . The check valve allows oil to be supplied from the pressure chamber to the cushion chamber.

  According to such a flow rate control valve, when the flow rate control spool returns to the neutral position, the oil discharged from the cushion chamber is throttled by the damping orifice. Therefore, since the return speed of the flow control spool can be slowed to reduce its inertia, the situation where the flow control spool moves beyond the neutral position and the situation where the flow control spool reciprocates (chattering) are prevented. Is possible.

  Moreover, the pilot pressure supplied to the pressure chamber is immediately guided to the cushion chamber through the communication oil passage, and the pressure for moving the flow rate control spool can be applied with good response.

JP 2001-193850 A

  By the way, in the above-described flow control valve, when the flow control spool is actually moved, it is necessary to discharge the oil filled in the opposite cushion chamber to the pressure chamber. When the oil is discharged from the cushion chamber to the pressure chamber, the check valve remains closed, so that only the damping orifice is provided. As a result, the oil filled in the cushion chamber may hinder the return movement of the flow control spool and reduce the response.

  In view of the above circumstances, the present invention provides a flow control valve, a directional control valve unit, and a hydraulic circuit that can reliably improve the responsiveness without causing an inadvertent operation of the flow control spool. Objective.

  In order to achieve the above object, a flow control valve according to claim 1 of the present invention applies a pilot pressure to an end of a flow control spool disposed in a valve body, and the flow control spool according to a change in the pilot pressure. Is a flow rate control valve that controls the flow rate of oil from the input port to the output port of the valve body, and accommodates one end portion of the flow rate control spool that protrudes to the outside of the valve body. A pressure chamber is formed between the pilot case, a pilot oil passage for applying pilot pressure to the pressure chamber is provided, and a pressing member that presses the flow control spool toward the other end is accommodated in the pilot case. Furthermore, a connecting oil passage and a throttle oil passage having an opening area smaller than that of the connecting oil passage are arranged between the pressure chamber and the pilot oil passage. Manner provided, characterized by selectively opening and closing these communication oil passage and the throttle oil passage in accordance with the operating position of the flow control spool.

  Further, the flow control valve according to claim 2 of the present invention communicates the output oil passage having a throttle with the output port of the valve body, and operates the flow control spool according to the differential pressure across the throttle. A flow rate control valve for controlling a flow rate of oil from an input port to an output port of the valve body, wherein the flow rate control spool is provided between one end projecting outside the valve body and a pilot case accommodating the end portion. A pilot oil passage is provided that constitutes a pressure chamber and introduces the pressure after the throttling as a pilot pressure into the pressure chamber, and a pressing member that presses the flow control spool toward the other end side is provided in the pilot case. Furthermore, a connecting oil passage and a throttle oil passage having an opening area smaller than that of the connecting oil passage are provided in parallel between the pressure chamber and the pilot oil passage. Characterized by selectively opening and closing these communication oil passage and the throttle oil passage in accordance with the operating position of the flow control spool.

  A flow control valve according to a third aspect of the present invention is the flow control valve according to the first or second aspect, wherein the flow control spool is provided between the input port and the output port of the valve body according to the operating position. And a retainer portion disposed inside the pilot case so as to be displaced in accordance with the operation of the spool portion, and the throttle oil passage includes the retainer portion. The communication oil passage is formed by providing a notch at a portion where the retainer portion and the inner wall surface of the pilot case are in sliding contact with each other. It is configured and is opened and closed according to a sliding contact position with the inner wall surface of the pilot case.

  A flow control valve according to a fourth aspect of the present invention is the flow control valve according to the first or second aspect, wherein the flow control spool is provided between the input port and the output port of the valve body according to the operating position. The communication oil passage is configured by providing a notch in a portion where the flow control spool and the inner wall surface of the pilot case are in sliding contact with each other, and the operation of the flow control spool In the region where the opening area between the input port and the output port changes at the bending point, the space between the pressure chamber and the pilot oil passage is closed, and the throttle oil passage is at least the communication oil passage When the pressure chamber and the pilot oil passage are closed, the pressure chamber and the pilot oil passage communicate with each other. To.

  The flow control valve according to claim 5 of the present invention is the flow control valve according to claim 1 or 2, wherein the throttle oil passage passes oil from the pressure chamber toward the pilot oil passage. It operates so as to increase the opening area.

  A directional control valve unit according to claim 6 of the present invention includes a flow control valve according to claim 1 or claim 2 and a supply / discharge control for supplying and discharging oil to a hydraulic cylinder in accordance with an operation position. A control spool, wherein the supply / discharge control spool is disposed in the valve body in such a manner that the operation axes coincide with each other on the extension of the other end of the flow control spool, and the supply / discharge control spool is operated to the discharge position. When the hydraulic cylinder oil is discharged, the flow control spool is operated so as to communicate between the input port and the output port of the valve body by the pressing force of the pressing member. The oil is discharged to the output oil passage.

  A hydraulic circuit according to a seventh aspect of the present invention is characterized in that an oil supply control and a discharge control for the hydraulic cylinder are performed by the direction control valve unit according to the sixth aspect.

  The hydraulic circuit according to claim 8 of the present invention communicates an output oil passage having a throttle with an output port of a valve body, and connects an input port of the valve body to a piston chamber of a hydraulic cylinder. A flow rate control valve that controls the flow rate of oil discharged from the piston chamber of the hydraulic cylinder by operating a flow rate control spool according to the differential pressure before and after, a supply control of oil to the hydraulic cylinder according to an operation position, and A supply / discharge control spool for performing discharge control, wherein the supply / discharge control spool is disposed on the valve body in such a manner that the operation axes coincide with each other on the other end extension of the flow control spool; When the oil in the hydraulic cylinder is discharged by operating to the discharge position, the flow control spool is moved so as to communicate between the input port and the output port of the valve body. A hydraulic control circuit for discharging oil from a piston chamber of the hydraulic cylinder through both the flow control valve and the direction control valve, wherein the flow control spool is in its operating position. A spool portion that changes an opening area between the input port and the output port of the valve body according to the above, and a retainer portion that is disposed so as to be displaced according to the operation of the spool portion, A pilot oil passage that forms a pressure chamber between a retainer portion that protrudes outside the valve body in the flow control spool and a pilot case that houses the retainer portion, and introduces the pressure after the throttle into the pressure chamber as a pilot pressure. And a spring member that presses the flow rate control spool toward the other end via the retainer portion. In addition, a throttle oil passage provided in a portion that always communicates between the pressure chamber and the pilot oil passage in the retainer portion, and the retainer portion and the inner wall surface of the pilot case are in sliding contact with each other. By providing a notch in the part, the opening area is configured to be larger than that of the throttle oil passage, and selectively between the pressure chamber and the pilot oil passage according to the operation position of the flow control spool. A communication oil passage that communicates, and is configured to block the communication oil passage in a region where an opening area between the input port and the output port due to the operation of the flow rate control spool changes at a bending point. And

  According to the present invention, the communication oil passage and the throttle oil passage are selectively opened and closed according to the operation position of the flow control spool, so that the throttle oil passage is only in the region that prevents inadvertent operation of the flow control spool. Can be activated. Therefore, inadvertent operation of the flow control spool can be prevented, and the responsiveness can be improved reliably.

  Exemplary embodiments of a flow control valve, a directional control valve unit, and a hydraulic circuit according to the present invention will be described below in detail with reference to the accompanying drawings.

  FIG. 1 is a hydraulic circuit diagram showing a directional control valve unit according to an embodiment of the present invention, and FIG. 2-1 is an enlarged view of a main part thereof. The hydraulic circuit exemplified here is for performing oil supply control and discharge control with respect to a single-acting hydraulic cylinder 1 applied as, for example, a lift cylinder of a forklift, and includes a direction control valve unit 10. .

  The directional control valve unit 10 has a drain port 12, a cylinder port 13, a pump port 14, an input port 15, and an output port 16 in the valve body 11, and these ports 12, 13, 14, 15, 16 communicate with each other. The spool hole 17 is provided with a supply / discharge control spool 20 and a flow rate control spool 30.

  The drain port 12 of the valve body 11 is the port located on the leftmost side in FIG. 1 and is connected to the oil tank T via an output oil passage 41 having a throttle 40. The cylinder port 13 is a port adjacent to the drain port 12 and is connected to the piston chamber 1 a of the hydraulic cylinder 1 through a supply / discharge oil passage 43 having a pilot check valve 42. The pilot check valve 42 always allows oil to pass through the piston chamber 1a of the hydraulic cylinder 1, while allowing oil to pass from the piston chamber 1a of the hydraulic cylinder 1 only when the pilot pressure is drained. .

  A pilot drain passage 44 for draining the pilot pressure of the pilot check valve 42 communicates with the drain passage 21 of the supply / discharge control spool 20 via an electromagnetic switching valve 45. The drain passage 21 is a space formed in the central portion of the supply / discharge control spool 20 along the axial direction, and is opened to the outer peripheral surface of the supply / discharge control spool 20 via a drill hole 22 formed along the radial direction. is doing. The electromagnetic switching valve 45 opens the pilot drain passage 44 only when a control signal is given. The control signal for opening the electromagnetic switching valve 45 is configured to be output when the driver is seated on the driver seat of the forklift, for example.

  The pump port 14 is a port adjacent to the cylinder port 13 with the communication port 18 in between, and is connected to the hydraulic pump P through a supply oil passage 46. The input port 15 is a port adjacent to the pump port 14 with the sub port 19 interposed therebetween, and is connected to the piston chamber 1a of the hydraulic cylinder 1 through the supply / discharge oil passage 43 having the pilot check valve 42 described above. The output port 16 is a port adjacent to the input port 15 and is connected to the oil tank T via the output oil passage 41 having the throttle 40 described above.

  The supply / discharge control spool 20 and the flow rate control spool 30 are each provided with cylindrical spool portions 20S, 30S having notches at appropriate positions on the outer peripheral surface, and the shaft centers of the spool portions 20S, 30S are aligned with each other. In this state, the end surfaces are brought into contact with each other and are fitted into the spool holes 17 of the valve main body 11 so as to be movable in the axial direction.

  Among these, the spool portion of the supply / discharge control spool 20 (hereinafter referred to as “lift spool portion 20 </ b> S”) extends from the drain hole 12, the cylinder port 13, the communication port 18, and the pump port 14 in the spool hole 17 of the valve body 11. The connection state of the drain port 12, the cylinder port 13, the communication port 18, and the pump port 14 is switched when moved along the axial direction.

  Specifically, in the state where the lift spool portion 20S is disposed at the neutral position shown in FIG. 1, the first notch 20Sa formed on the outer peripheral surface of the lift spool portion 20S is located only at the communication port 18, and the lift The second notch 20Sb of the spool portion 20S is located only at the cylinder port 13. As a result, the drain port 12, the cylinder port 13, the communication port 18 and the pump port 14 of the valve body 11 are in a state of being blocked from each other. At this time, the drill hole 22 communicating with the above-described drain passage 21 is located slightly to the right of the drain port 12 between the drain port 12 and the cylinder port 13, and the opening on the outer peripheral surface thereof is a spool hole. 17 is closed by the inner peripheral surface.

  When the lift spool portion 20S moves from the neutral position to the right side in FIG. 1 (hereinafter referred to as “lift side”), as shown in FIG. 4, the pump port 14 is caused by the first notch 20Sa of the lift spool portion 20S. And the communication port 18 are connected to each other, and the communication port 18 and the cylinder port 13 are connected to each other by the second notch 20Sb formed on the outer peripheral surface of the lift spool portion 20S. That is, when the lift spool portion 20S moves from the neutral position to the lift side in FIG. 1, the pump port 14 and the cylinder port 13 of the valve body 11 are connected to each other. The opening area between the pump port 14 and the cylinder port 13 by the first notch 20Sa and the second notch 20Sb is configured to increase as the moving amount of the lift spool portion 20S increases. The drill hole 22 communicating with the drain passage 21 is also displaced by the movement of the lift spool portion 20S. However, when the lift spool portion 20S moves to the lift side in FIG. 1, as shown in FIG. Is located between the drain port 12 and the cylinder port 13 in the spool hole 17 and still remains closed by the inner peripheral surface of the spool hole 17.

  On the other hand, when the lift spool portion 20S moves from the neutral position to the left side in FIG. 1 (hereinafter referred to as “down side”), as shown in FIG. 5, FIG. 6, FIG. The drain port 12 and the cylinder port 13 are connected to each other by the notch 20Sb. The opening area between the drain port 12 and the cylinder port 13 by the second notch 20Sb is configured to increase as the amount of movement of the lift spool portion 20S to the down side increases. When the lift spool portion 20S moves to the down side, the drill hole 22 of the drain passage 21 immediately moves to a position where it communicates with the drain port 12, and the drain port 12 and the drain passage 21 are connected to each other. become.

  On the other hand, the spool portion of the flow rate control spool 30 (hereinafter referred to as “downcon spool portion 30S”) is disposed at a portion extending over the input port 15 and the output port 16 in the spool hole 17 of the valve body 11, and is axially oriented. In this case, the connection state between the input port 15 and the output port 16 is switched.

  More specifically, in the state where the downcon spool portion 30S is disposed at the neutral position shown in FIG. 1, the third notch 30Sa formed on the outer peripheral surface of the downcon spool portion 30S is located only at the output port 16, and the valve body 11 input ports 15 and output ports 16 are blocked from each other.

  When the downcon spool portion 30S moves from the neutral position to the down side in FIG. 1, the third notch 30Sa of the downcon spool portion 30S is connected to the input port 15 as shown in FIG. 5, FIG. 6, FIG. The input port 15 and the output port 16 are connected to each other. The opening area between the input port 15 and the output port 16 by the third notch 30Sa is configured to increase as the amount of movement of the downcon spool portion 30S to the down side increases. In particular, in the present embodiment, as shown in FIG. 9C, the opening area between the input port 15 and the output port 16 changes with the bending point X, and the down-compression portion 30S moves to the down side. In this case, the third notch 30Sa is configured so that the amount of change in the later stage of operation is larger than that in the early stage of operation.

  On the other hand, when the downcon spool portion 30S moves from the neutral position to the lift side in FIG. 1, the third notch 30Sa is positioned only at the output port 16 as shown in FIG. And the output port 16 are kept separated from each other.

  The downcon spool portion 30S applied in the present embodiment is a so-called “step spool”, and the outer diameter of the portion 30SR located on the right side of the third notch 30Sa in FIG. The outer diameter of the portion 30SL located on the left side of the three notches 30Sa is configured to be larger. When this downcon spool portion 30S is viewed from the left end face, an annular step portion 30C is formed between the two portions 30SR and 30SL as shown in FIG.

  As apparent from FIG. 1, in the present embodiment, the operation input portion 20M is provided at the end of the lift spool portion 20S of the supply / discharge control spool 20 that protrudes outside the valve body 11, while the flow rate control spool A retainer portion 30M is provided at an end portion of the 30 downcon spool portion 30S that protrudes outside the valve body 11.

  The operation input portion 20M of the supply / discharge control spool 20 is a portion to which power for moving the lift spool portion 20S is input in response to an operation of an operation lever (not shown), and lifts in a state where the axes are aligned with each other. It is fixed to the end of the spool portion 20S. The operation input portion 20M has a base end portion that has substantially the same outer diameter as the lift spool portion 20S, while the connecting portion with the lift spool portion 20S has a small cylindrical shape, and the connecting portion configured to have a small diameter. A pair of spring seats 23 is provided at 20 Ma. Each of the spring seats 23 is movably disposed so that the connecting portion 20Ma passes through each central hole and the base end portion of the operation input portion 20M and the lift spool portion 20S are moved closer to and away from each other. Between these spring seats 23, there is interposed a lift-side pressing spring 24 that keeps them separated from each other. The spring seat 23 and the lift side pressing spring 24 are accommodated in a spring case 25 attached to the valve body 11. In the spring case 25, one spring seat 23 abuts the outer surface of the valve body 11 via the washer plate 26 in a state where the pair of spring seats 23 are most separated from each other by the pressing force of the lift-side pressing spring 24. The size of the spring seat 23 is sufficient to abut against the inner wall surface of the spring case 25. In addition, the code | symbol 27 in FIG. 1 is the oil seal member interposed between the valve main body 11 and the lift spool part 20S.

  The supply / discharge control spool 20 configured as described above has a pair of spring seats 23 positioned at both ends of the connecting portion 20Ma by lift-side pressing springs 24 when no operating force is applied to an operating lever (not shown). These spring seats 23 are maintained in contact with the inner wall surface of the spring case 25 and the outer surface of the valve body 11, and the lift spool portion 20S is disposed at the neutral position shown in FIG. When an operation lever (not shown) is operated from this neutral position and an operation force is applied to the operation input unit 20M against the pressing force of the lift-side pressing spring 24, the lift spool portion 20S in FIG. Can be moved in both directions. When the operating force applied to the operation input unit 20M is removed from the state in which the lift spool unit 20S is moved, the lift spool unit 20S returns to the neutral position by the pressing force of the lift side pressing spring 24.

  On the other hand, the retainer portion 30 </ b> M of the flow control spool 30 is accommodated in a pilot case 31 attached to the outer surface of the valve body 11. This retainer portion 30M has a cylindrical shape with one end portion having a diameter larger than that of the other end portion, and has an accommodation recess 30a on one end surface. The end portion of the downcom spool portion 30S is placed inside the accommodation recess 30a. It is arranged on the extension of the downcon spool portion 30S in the arranged state.

  As shown in FIGS. 1 and 2-1, the pilot case 31 that accommodates the retainer portion 30M has a longer length along the axial center direction than the retainer portion 30M, and the retainer portion 30M. An annular sliding contact rib 31a is provided on the inner peripheral surface located on the one end side. The sliding contact rib 31a is configured to be fitted to one end portion of the retainer portion 30M via its inner peripheral surface. The sliding contact rib 31a guides the movement of the retainer portion 30M along the axial direction by sliding contact with the outer peripheral surface of one end of the retainer portion 30M, and divides the interior of the pilot case 31 into two chambers 32 and 33. It has a function to do. A chamber formed between the pilot case 31 and the other end of the retainer 30M (hereinafter referred to as “pressure chamber 32”), and between the pilot case 31 and one end of the retainer 30M and the valve body 11 are configured. The chambers 33 (hereinafter referred to as “pilot chambers (pilot oil passages) 33”) have their respective volumes changed as the retainer portion 30M moves. In the present embodiment, both the end surfaces of the retainer portion 30M are piloted in a state where the downcon spool portion 30S is disposed at the neutral position described above and the end surface of the retainer portion 30M and the end surface of the downcon spool portion 30S are in contact with each other. The dimensions of the pilot case 31 are set so as to be separated from the inner wall surface of the case 31 and the outer surface of the valve body 11.

  A spool spring (pressing member) 34 is disposed between the pressure chamber 32 of the pilot case 31 and the retainer portion 30M. The spool spring 34 is a coil spring disposed along the axis of the downcon spool portion 30S, and always presses the retainer portion 30M toward the downcon spool portion 30S, and further, the end surface of the downcon spool portion 30S is moved to the lift spool portion 20S. It presses against the end face.

  An introduction oil passage (pilot oil passage) 35 and a lead-out oil passage 36 are connected to the pilot chamber 33 of the pilot case 31. The introduction oil passage 35 is connected to the output oil passage 41 on the downstream side of the throttle 40 described above, and connects the pilot chamber 33 to the oil tank T through the output oil passage 41. The introduction oil passage 35 is formed so as to open at a position closer to the valve body 11 than the sliding contact rib 31 a on the inner peripheral surface of the pilot case 31. The lead-out oil passage 36 connects the pilot chamber 33 and the subport 19 of the valve body 11 to each other. The lead-out oil passage 36 is formed at the center along the axial direction of the downcon spool portion 30S. Is open. As is apparent from FIG. 2A, the outlet oil passage 36 of the downcon spool portion 30S is provided with a spring accommodating portion 36a and a through hole 36b at an end portion close to the retainer portion 30M. The spring accommodating portion 36a is a portion having a large inner diameter, and an auxiliary spring 37 is disposed therein. The auxiliary spring 37 presses the retainer portion 30M in a direction separating the retainer portion 30M from the downcon spool portion 30S. The auxiliary spring 37 has a set load smaller than that of the spool spring 34 disposed in the pressure chamber 32. The through hole 36b is an opening formed along the radial direction of the downcon spool portion 30S, and always communicates between the spring accommodating portion 36a and the pilot chamber 33.

  As shown in FIGS. 1 and 2-1, a throttle oil passage 50 and a communication oil passage 60 are provided in parallel between the pressure chamber 32 and the pilot chamber 33 of the pilot case 31. The throttle oil passage 50 is a passage formed in the central portion along the axial direction of the retainer portion 30M, and includes a movable valve body 51 in the middle portion thereof. The movable valve body 51 has a pore 51a inside and is disposed so as to be detachable from a valve seat 52 provided in the throttle oil passage 50. In the throttle oil passage 50, when oil passes from the pressure chamber 32 toward the pilot chamber 33, the movable valve body 51 is separated from the valve seat 52, so that the original opening area formed in the retainer portion 30M is secured. The On the other hand, when the oil passes from the pilot chamber 33 toward the pressure chamber 32, the movable valve body 51 comes into contact with the valve seat 52 so that only the pore 51a of the movable valve body 51 has an opening area. The passage of will be greatly squeezed.

  The communication oil passage 60 is configured by forming a notch 61 on the outer peripheral surface of one end of the retainer portion 30M. In the present embodiment, as shown in FIG. 2-1, two communication oil passages 60A and 60B are formed by forming notches 61A and 61B having different forms at two different locations of the retainer portion 30M. ing.

  The first communication oil passage 60A is axially directed from the intermediate position of the portion facing the sliding contact rib 31a of the pilot case 31 toward the pressure chamber 32 in a state where the retainer portion 30M is disposed at the neutral position shown in FIG. It is comprised by forming the notch 61A along. The cutout 61A constituting the first communication oil passage 60A is configured such that the opening area gradually increases as the retainer portion 30M moves to the down side.

  When the retainer section 30M moves from the neutral position shown in FIG. 1 to the lift side, the first communication oil passage 60A always opens only to the pressure chamber 32 as shown in FIG. 33 is maintained in a state of being interrupted. On the other hand, when the retainer portion 30M moves from the neutral position shown in FIG. 1 to the down side, the first communication oil passage 60A opens only to the pressure chamber 32 in the initial stage of movement, and the end surface of the retainer section 30M is the valve in the late stage of movement. The pressure chamber 32 and the pilot chamber 33 are communicated with each other until they contact the outer surface of the main body 11. More specifically, when the downcon spool portion 30S and the retainer portion 30M are interlocked, as shown in FIGS. 9B and 9C and FIGS. 60A is a position in FIG. 6 (hereinafter referred to as “below the position“ down operation 1 position ”) from the position in FIG. 5 before reaching the bending point X of the third notch 30Sa (hereinafter referred to as“ down operation 1 position ”). Up to “down operation 2 position”), only the pressure chamber 32 is opened and the pilot chamber 33 is maintained in a disconnected state. As shown in FIGS. 9B and 9C and FIGS. 7 and 8, the end surface of the retainer portion 30M is brought into contact with the outer surface of the valve body 11 from the position after passing the down operation 2 position. 7 and FIG. 8 in contact (hereinafter, the position in FIG. 7 is referred to as “down operation 3 position”, and the position in FIG. 8 is referred to as “down operation 4 position”). The pressure chamber 32 and the pilot chamber 33 communicate with each other so as to increase.

  When the retainer portion 30M is located at the neutral position shown in FIG. 1, the second communication oil passage 60B exceeds the sliding contact rib 31a of the pilot case 31 on the outer peripheral surface of the retainer portion 30M. Is formed by forming a notch 61B along the axial direction from the position facing the inside toward the pilot chamber 33. In the neutral position shown in FIG. 1, the notch 61 </ b> B constituting the second communication oil passage 60 </ b> B is constituted by a large part and a small part until the notch 61 B faces the sliding contact rib 31 a from the pilot chamber 33. In (b), the opening area is set from the neutral to the lift side.

  When the retainer portion 30M moves from the neutral position shown in FIG. 1 to the lift side, the second communication oil passage 60B has a pressure so that its opening area gradually increases according to the amount of movement as shown in FIG. The chamber 32 communicates with the pilot chamber 33. On the other hand, when the retainer portion 30M moves from the neutral position shown in FIG. 1 to the down side, the second communication oil passage 60B is formed between the pressure chamber 32 and the pilot chamber 33 by the notch 61B having a small opening area in the initial movement. In communication, the space between the pressure chamber 32 and the pilot chamber 33 is shut off in the later stage of movement. More specifically, when the downcon spool portion 30S and the retainer portion 30M are interlocked, as shown in FIGS. 9B and 9C and FIG. 5, the bending point X of the third notch 30Sa is In the down operation 1 position before reaching the second communication oil passage 60B, the pressure chamber 32 and the pilot chamber 33 are maintained in communication with each other by the notch 61B having a small opening area. After passing through this down operation 1 position, as shown in FIGS. 9B and 9C and FIGS. 6, 7, and 8, the second communication oil passage 60B enters the pilot chamber 33. Only the opening is made, and the state where the pressure chamber 32 and the pilot chamber 33 are blocked is maintained.

  In the flow control spool 30 in which the throttle oil passage 50, the first communication oil passage 60A and the second communication oil passage 60B are configured as described above, the total opening secured between the pressure chamber 32 and the pilot chamber 33. The area has characteristics as shown in FIG. That is, when the flow rate control spool 30 moves from the neutral position to the down side, only the first communication oil passage 60A communicates between the pressure chamber 32 and the pilot chamber 33 until the down operation 1 position ( Section A1 → A2).

  In the range from the down operation 1 position to the down operation 2 position, that is, in the range including the bending point X of the third notch 30Sa formed in the downcon spool portion 30S in the state where the flow control spool 30 is moving to the down side. The pressure chamber 32 and the pilot chamber 33 communicate with each other only by the fine holes 51a formed in the movable valve body 51 of the throttle oil passage 50 (section A2 → A3).

  When the flow rate control spool 30 has moved to the down side beyond the down operation 2 position, the second communication oil passage 60B until the one end surface of the retainer portion 30M comes into contact with the outer surface of the valve body 11. As a result, the pressure chamber 32 and the pilot chamber 33 communicate with each other (section A3 → A4). In the state shown in FIG. 8, although the supply / discharge control spool 20 and the downcon spool portion 30S move to the down side, the retainer portion 30M that contacts the outer surface of the valve body 11 does not move to the down side. Therefore, the pressure chamber 32 and the pilot chamber 33 are communicated with each other by a constant opening through the second communication oil passage 60B (section A4 → A5).

  In any of the above-described states, when the flow control spool 30 moves to the lift side, the movable valve body 51 is separated from the valve seat 52 in the throttle oil passage 50, so it always moves to the down side. The pressure chamber 32 and the pilot chamber 33 communicate with each other with a larger opening area than the throttle oil passage 50 (section A6 → A11). When the flow rate control spool 30 moves from the position closest to the lift side to the neutral position, the pressure chamber 32 and the pilot chamber 33 are maintained in communication with each other through the second communication oil passage 60B. (Section A12 → A1).

  FIG. 3 is a hydraulic circuit diagram schematically showing the function of the direction control valve unit 10 in the hydraulic circuit described above. Hereinafter, the operation of the hydraulic circuit will be described with reference to FIGS. In the following description, the supply / discharge control spool 20 and the flow rate control spool 30 may be collectively referred to simply as “control spools 20 and 30”.

  First, when the driver is not seated in the driver's seat and the control spools 20 and 30 are in the neutral position, as shown in FIGS. 1 and 3, the drain port 12, the cylinder port 13 and the pump of the valve body 11 are used. Each of the ports 14 is blocked from each other, and the input port 15 and the output port 16 are blocked from each other. Therefore, no oil flows to the piston chamber 1a of the hydraulic cylinder 1, and the hydraulic cylinder 1 maintains the current piston position.

  As shown in FIGS. 1 and 3, when the driver is not seated, the electromagnetic switching valve 45 is maintained in a state in which the pilot drain passage 44 is closed, so that the pilot pressure of the pilot check valve 42 is drained. The oil filled in the piston chamber 1a of the hydraulic cylinder 1 does not flow out to the outside. Therefore, even if the control spools 20 and 30 are erroneously operated from a state in which the load is lifted up by the hydraulic cylinder 1, there is no possibility that the hydraulic cylinder 1 will be contracted due to the weight of the load.

  When the driver is seated on the driver's seat from this state, the electromagnetic switching valve 45 is activated and the pilot drain passage 44 is opened. Further, when the control spools 20 and 30 are moved to the lift side against the pressing force of the spool spring 34 and the lift side pressing spring 24 by operating an operation lever (not shown), as shown in FIG. The pump port 14 and the cylinder port 13 of the valve body 11 are connected to each other, while the input port 15 and the output port 16 are kept separated from each other. As a result, the oil discharged from the hydraulic pump P enters the piston chamber 1a of the hydraulic cylinder 1 through the supply oil passage 46, the pump port 14, the communication port 18, the cylinder port 13, the supply / discharge oil passage 43, and the pilot check valve 42. As a result, the hydraulic cylinder 1 is extended. Therefore, for example, it is possible to lift up the load that is the object to be transported mounted on the fork of the forklift to a desired height position.

  Here, when the control spools 20 and 30 are moved to the lift side, the retainer portion 30M of the flow rate control spool 30 also moves to the lift side, so that the oil remains in the pressure chamber 32 of the pilot case 31 while being stored. As a result, the movement of the control spools 20 and 30 is suppressed. That is, in order to move the control spools 20 and 30 to the lift side with good response, it is necessary to drain the oil stored in the pressure chamber 32.

  In this case, according to the directional control valve unit 10, the movable valve body 51 is separated from the valve seat 52, so that a large opening area of the throttle oil passage 50 is ensured, and with the movement of the retainer portion 30 </ b> M to the lift side. Since the second communication oil passage 60 </ b> B is largely opened, the oil stored in the pressure chamber 32 is immediately drained to the oil tank T through the pilot chamber 33 and the introduction oil passage 35. As a result, when the control spools 20 and 30 are operated, there is no possibility that the oil in the pressure chamber 32 acts to suppress this, and the load can be lifted up with good response by a light operating force.

  When the operation force applied to the operation lever (not shown) is removed from the state shown in FIG. 4, the control spool 20 and the control spool 20 are applied to the valve body 11 by the elastic restoring force of the spool spring 34 and the lift-side pressing spring 24 described above. 30 moves down and stops at the neutral position shown in FIG.

  Here, when the control spools 20 and 30 are returned to the neutral position from the state shown in FIG. 4, the retainer portion 30M of the flow rate control spool 30 also moves to the down side. In order to prevent the pressure from being reduced, it is necessary to allow oil to flow in.

  In this case, according to the directional control valve unit 10, since the second communication oil passage 60B is continuously opened until the neutral position is reached, the pilot chamber 33 can be opened through the second communication oil passage 60B. Oil is immediately supplied to the pressure chamber 32. As a result, when the control spools 20 and 30 are operated, the pressure chamber 32 is in a reduced pressure state and there is no fear of acting to suppress this, and the neutral position is returned with good response. In addition, in the state immediately before the control spools 20 and 30 reach the neutral position, the opening area of the second communication oil passage 60B decreases rapidly, so that the inflow of oil into the pressure chamber 32 is restricted, and the control spool It functions to suppress the movement of 20, 30 to the down side. As a result, it is possible to prevent the control spools 20 and 30 from overshooting to the down side beyond the neutral position.

  When the control spools 20 and 30 return to the neutral position as described above, the drain port 12, the cylinder port 13 and the pump port 14 of the valve body 11 are again cut off from each other as shown in FIGS. In addition, the input port 15 and the output port 16 are blocked from each other. Therefore, even when a heavy load is lifted up, no oil flows to the piston chamber 1a of the hydraulic cylinder 1, and the hydraulic cylinder 1 maintains the current piston position.

  On the other hand, if the control spools 20 and 30 are moved to the down side against the pressing force of the lift side pressing spring 24 by operating an operation lever (not shown) from the neutral position shown in FIG. As shown in FIG. 8, the drain port 12 and the cylinder port 13 of the valve body 11 are connected to each other, and the input port 15 and the output port 16 are connected to each other. Further, when the control spools 20 and 30 move down, the drill hole 22 of the drain passage 21 immediately moves to a position where it communicates with the drain port 12, and the pilot pressure of the pilot check valve 42 is drained to the drain port 12. Is done. As a result, the oil stored in the piston chamber 1a of the hydraulic cylinder 1 passes through the supply / discharge oil passage 43, the pilot check valve 42, the cylinder port 13, the drain port 12, and the output oil passage 41 to the oil tank T. The oil tank T is drained by two paths: a supply / discharge oil path 43, a pilot check valve 42, an input port 15, and a path reaching the oil tank T via the output oil path 41. Accordingly, the hydraulic cylinder 1 is retracted by the weight of the load, and the lifted up load can be lowered.

  During this time, according to the directional control valve unit 10, the position of the lift spool portion 20S is controlled according to the amount of operation of an operation lever (not shown), while the downcon spool portion is separate from the position of the lift spool portion 20S. The position of 30S will be controlled. In other words, the pressure of the output port 16 acts on the downcon spool portion 30S so as to move the annular stepped portion 30C shown in FIG. 2-2 to the lift side, while the pressing force of the spool spring 34 moves to the down side. It works to let you. As a result, the downcon spool portion 30S moves to a position where the pressure of the output port 16 acting on the step portion 30C and the pressing force of the spool spring 34 are balanced, and the opening area between the input port 15 and the output port 16 is reduced. By changing the flow rate, the flow rate of the passing oil is controlled. The pressure of the oil acting on the stepped portion 30C of the downcon spool portion 30S is a differential pressure between the output port 16 that is the hydraulic pressure before throttling and the chambers 32 and 33 and the subport 19 of the pilot case 31 that are the hydraulic pressure after throttling. .

  For example, when the lifted up load is relatively heavy, the amount of oil discharged from the piston chamber 1a of the hydraulic cylinder 1 is significantly increased. For this reason, the flow rate passing through the throttle 40 increases, and the hydraulic pressure of the input port 15 and the output port 16 upstream of the throttle 40 also increases. As a result, the downcon spool portion 30S is separated from the end surface of the lift spool portion 20S and moves to the lift side against the pressing force of the spool spring 34, whereby the input port 15 and the output port 16 by the third notch 30Sa are connected. The opening area between them is smaller than that set by an operation lever (not shown). As a result, the flow rate of the oil discharged from the piston chamber 1a of the hydraulic cylinder 1 is limited, and the speed of the contraction operation, that is, the load lowering speed can be suppressed.

  On the other hand, if the opening area between the input port 15 and the output port 16 due to the third notch 30Sa becomes too small, the oil flowing through the input port 15 and the output port 16 is reduced. 30S moves down. As a result, the opening area between the input port 15 and the output port 16 due to the third notch 30Sa of the down-conspool portion 30S increases. That is, the flow rate of oil discharged from the piston chamber 1a of the hydraulic cylinder 1 increases.

  Thereafter, the above-described operation is repeatedly performed, and the down-comp spool portion 30S is always set so that the difference between the hydraulic pressure of the input port 15 and the output port 16 and the hydraulic pressure of the chambers 32 and 33 of the pilot case 31 and the sub-port 19 is constant. The flow rate of the oil that moves and drains to the oil tank T through the output oil passage 41 is controlled.

  When the lifted load is relatively light, the amount of oil discharged from the piston chamber 1a of the hydraulic cylinder 1 does not increase significantly, and the input port 15 and the output port 16 The hydraulic pressure is also small. As a result, the downcon spool portion 30S maintains its end surface in contact with the end surface of the lift spool portion 20S without moving to the lift side, and the third notch 30Sa is set to a downconset set by an operation lever (not shown). The opening area of the spool portion 30S remains unchanged. As a result, the oil is efficiently discharged through the two paths described above, and the load can be lowered quickly.

  By the way, in the present embodiment, as described above, the opening area between the input port 15 and the output port 16 is bent as the third notch 30Sa of the downcon spool portion 30S as shown in FIG. When the change occurs at the point X and the down-conspooling section 30S moves to the down side, the one in which the amount of change in the later stage of operation becomes larger than the initial stage of operation is applied. For this reason, when the set position of the control spools 20 and 30 by the operation of the operation lever (not shown) is near the bending point X, the downcon spool portion 30S is used in the flow rate control based on the pressure difference described above. There is a possibility that a vibration phenomenon called chattering will be caused. That is, when the bending point X is exceeded, the flow rate of the oil changes abruptly. Therefore, the downcon spool portion 30S that moves to the down side and exceeds the bending point X immediately moves to the lift side. There is a possibility that the excess down-conspool portion 30S immediately moves to the down side.

  When chattering occurs in the downcon spool portion 30S, the flow rate of the oil discharged from the piston chamber 1a of the hydraulic cylinder 1 changes accordingly, and there is a possibility that the hydraulic cylinder 1 is affected by vibration.

  However, in the directional control valve unit 10 described above, the connecting oil passages 60A and 60B and the throttle oil passage 50 are provided in parallel between the pressure chamber 32 and the pilot chamber 33 in the pilot case 31, and the down operation is performed from the down operation 1 position. Between the two positions, the pressure chamber 32 and the pilot chamber 33 communicate with each other only by the throttle oil passage 50. That is, in the range including the bending point X of the third notch 30Sa formed in the downcon spool portion 30S in a state where the flow control spool 30 is moving to the down side, the first communication oil passage 60A and the second communication oil are used. While both the passages 60B are closed, only the pores 51a formed in the movable valve body 51 of the throttle oil passage 50 are opened, and the pressure chambers 32 and the pilot chambers 33 are communicated with each other by the pores 51a. It will be. As a result, the inflow of oil from the pilot chamber 33 to the pressure chamber 32 is greatly reduced, the moving speed of the downcon spool portion 30S is greatly suppressed, and there is no possibility of causing chattering.

  In addition, when the downcon spool portion 30S moves to the down side beyond the down operation 2 position, the first communication oil passage 60A is opened, and the pressure chamber 32 is released from the pilot chamber 33 through the first communication oil passage 60A. Since the oil flows in, the movement of the downcon spool portion 30S is facilitated, and the responsiveness is not greatly impaired.

  In the above-described embodiment, the direction control valve unit including the supply / discharge control spool is illustrated, but the flow control valve without the supply / discharge control spool may be configured. In this case as well, as in the embodiment, chattering can be reliably prevented without significantly impairing the responsiveness of the downconspool section.

It is a figure which shows the hydraulic circuit containing the direction control valve unit which is embodiment of this invention. It is sectional drawing which expands and shows the principal part of the directional control valve unit shown in FIG. It is an end view of the flow control spool applied to the directional control valve unit shown in FIG. FIG. 2 is a hydraulic circuit diagram schematically showing a function of a directional control valve unit in the hydraulic circuit shown in FIG. 1. It is a figure which shows the lift operation position of the direction control valve unit shown in FIG. It is a figure which shows the down operation 1 position of the direction control valve unit shown in FIG. It is a figure which shows the down operation 2 position of the direction control valve unit shown in FIG. It is a figure which shows the down operation 3 position of the direction control valve unit shown in FIG. It is a figure which shows the down operation 4 position of the direction control valve unit shown in FIG. 2 is a graph showing changes in an opening area (communication oil passage + downcom spool opening area, communication oil passage opening area, downcon spool opening area) with respect to a stroke of a flow control spool in the directional control valve unit shown in FIG. 1;

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Valve body 15 Input port 16 Output port 30 Flow control spool 30M Retainer part 31 Pilot case 32 Pressure chamber 33 Pilot chamber 34 Spool spring 35 Introducing oil path 40 Throttle 50 Throttle oil path 60 Communication oil path 61 Notch X Bending point

Claims (8)

The flow rate of oil from the input port to the output port of the valve body by applying a pilot pressure to the end of the flow control spool disposed in the valve body and operating the flow control spool in accordance with the change of the pilot pressure. A flow control valve for controlling
In the flow rate control spool, a pressure chamber is formed between one end projecting outside the valve body and a pilot case that houses the end, and a pilot oil passage that applies pilot pressure to the pressure chamber is provided. A pressing member that presses the control spool toward the other end side is accommodated in the pilot case,
Further, a communication oil passage and a throttle oil passage having an opening area smaller than that of the communication oil passage are provided in parallel between the pressure chamber and the pilot oil passage, and according to the operating position of the flow control spool. A flow control valve characterized by selectively opening and closing the communication oil passage and the throttle oil passage. The oil flow from the input port to the output port of the valve body is controlled by communicating the output oil passage with the throttle with the output port of the valve body and operating the flow control spool according to the differential pressure across the throttle. A flow control valve for controlling,
A pilot oil that forms a pressure chamber between one end portion of the flow rate control spool that protrudes outside the valve body and a pilot case that accommodates the spool body, and introduces the pressure after the throttling into the pressure chamber as a pilot pressure. A path is provided, and a pressing member that presses the flow rate control spool toward the other end side is accommodated in the pilot case.
Further, between the pressure chamber and the pilot oil passage, a communication oil passage and a throttle oil passage having an opening area smaller than that of the communication oil passage are provided in parallel, and depending on the operating position of the flow control spool A flow control valve characterized by selectively opening and closing the communication oil passage and the throttle oil passage. The flow rate control spool has a spool portion that changes an opening area between the input port and the output port of the valve body according to its operating position, and the pilot case has a displacement so as to be displaced according to the operation of the spool portion. It has a retainer part arranged inside,
The throttle oil passage is configured in a portion that always communicates between the pressure chamber and the pilot oil passage in the retainer portion,
The communication oil passage is configured by providing a notch at a portion where the retainer portion and the inner wall surface of the pilot case are in sliding contact with each other, and opens and closes according to a sliding contact position with the inner wall surface of the pilot case. The flow control valve according to claim 1, wherein the flow control valve is provided. The flow rate control spool sequentially changes the opening area between the input port and the output port of the valve body according to its operating position.
The communication oil passage is configured by providing a notch in a portion where the flow control spool and the inner wall surface of the pilot case are in sliding contact with each other, and an opening between the input port and the output port by the operation of the flow control spool. In a region where the area changes with a bending point, the space between the pressure chamber and the pilot oil passage is closed.
The throttle oil passage is configured to communicate between the pressure chamber and the pilot oil passage when at least the communication oil passage closes between the pressure chamber and the pilot oil passage. The flow control valve according to claim 1 or 2.   3. The throttle oil passage according to claim 1, wherein the throttle oil passage operates so as to increase an opening area when oil is allowed to pass from the pressure chamber toward the pilot oil passage. Flow control valve. A flow control valve according to claim 1 or 2,
A supply / discharge control spool that controls the supply and discharge of oil to and from the hydraulic cylinder in accordance with the operating position, and the supply / discharge control spool is configured so that the operating axes coincide with each other on the other end extension of the flow control spool. When the hydraulic cylinder oil is discharged by operating the supply / discharge control spool to the discharge position and communicating with the input port and the output port of the valve main body. The directional control valve unit is characterized in that the oil in the hydraulic cylinder is discharged to the output oil passage by operating the flow rate control spool.   A hydraulic circuit that performs supply control and discharge control of oil to a hydraulic cylinder by the direction control valve unit according to claim 6. An output oil passage having a throttle is communicated with an output port of the valve body, and an input port of the valve body is connected to a piston chamber of a hydraulic cylinder, and a flow control spool is operated in accordance with a differential pressure across the throttle. A flow rate control valve for controlling the flow rate of oil discharged from the piston chamber of the hydraulic cylinder;
A supply / discharge control spool that performs supply control and discharge control of oil to the hydraulic cylinder in accordance with an operation position is provided, and the supply / discharge control spool is configured so that the operation axes coincide with each other on the other end extension of the flow control spool. The flow rate control spool is disposed in the valve body so as to communicate between the input port and the output port of the valve body when the hydraulic cylinder oil is discharged by operating the supply / discharge control spool to the discharge position. A hydraulic circuit that discharges oil from a piston chamber of the hydraulic cylinder through both the flow control valve and the directional control valve,
The flow rate control spool includes a spool portion that changes an opening area between the input port and the output port of the valve body according to the operation position, and a retainer that is disposed so as to be displaced according to the operation of the spool portion. With a part,
A pilot oil that forms a pressure chamber between a retainer portion that protrudes outside the valve body in the flow control spool and a pilot case that houses the retainer portion, and introduces the pressure after the throttle into the pressure chamber as a pilot pressure. A path member is provided, and a spring member that presses the flow rate control spool toward the other end side through the retainer portion is accommodated in the pilot case.
Furthermore, a notch is provided at a portion where the retainer portion and the throttle oil passage provided in the portion that always communicates between the pressure chamber and the pilot oil passage, and the portion where the retainer portion and the inner wall surface of the pilot case are in sliding contact with each other. Accordingly, the communication oil passage is configured such that the opening area is larger than that of the throttle oil passage, and selectively communicates between the pressure chamber and the pilot oil passage according to the operating position of the flow control spool. And
The hydraulic circuit, wherein the communication oil passage is closed in a region where an opening area between the input port and the output port due to the operation of the flow control spool changes at a bending point.

Images