JP2019056464A - Flow control valve - Google Patents

Abstract

To provide a flow control valve capable of highly accurately variably controlling a flow rate from an inlet side flow passage to an outlet side flow passage by suppressing an effect of fluid force and of improving responsiveness of a check valve.SOLUTION: A flow control valve 33 variably controls a flow rate from an inlet side flow passage 25 to an outlet side flow passage 27 by controlling displacement amount of a main valve 43 in accordance with opening amount of a pilot restrictor 56. A fixed restrictor 64 is provided between a back pressure chamber 47 and the outlet side flow passage 27. The fixed restrictor 64 communicates the back pressure chamber 47 and the outlet side flow passage 27 with each other without interposing a pilot flow passage 50. In addition, the fixed restrictor 64 fixes opening amount between the back pressure chamber 47 and the outlet side flow passage 27 regardless of the displacement amount of the main valve 43. In the pilot restrictor 56, opening amount of the pilot flow passage 50 becomes zero before the displacement amount of a pilot valve 55 reaches a maximum value.SELECTED DRAWING: Figure 3

Description

  The present invention relates to, for example, a flow rate control valve that is provided in a hydraulic circuit of a construction machine and controls the flow rate of hydraulic fluid supplied from a hydraulic pump to an actuator.

  In a hydraulic circuit of a construction machine such as a hydraulic excavator, a hydraulic crane, or a wheel loader, for example, a plurality of directional control valves that switch and control the flow rate and direction of hydraulic fluid supplied from a hydraulic pump to an actuator are used. At least one of the plurality of directional control valves is a seat valve type flow control valve in a supply oil passage from a hydraulic pump in which a check valve for preventing backflow from the actuator to the hydraulic pump is arranged (Patent Document) 1). This flow control valve opens and closes the main valve seat to open and close the first input port (inlet side flow path) on the hydraulic pump side and the first output port (outlet side flow path) on the actuator side in the supply oil path. A main valve having a valve part to be separated and seated, and a first variable throttle formed on the outer periphery of the main valve to a back pressure chamber of the main valve formed on the opposite side to the valve part in order to control the opening amount of the main valve A pilot valve having a second input port (pilot flow path) connected via a (feedback throttle) is provided. The second input port is connected to the first output port on the output side of the valve portion of the main valve via a second variable throttle (pilot throttle) formed in the pilot valve. The area ratio between the pressure receiving surface A1 that receives the hydraulic pressure of the first input port of the main valve and the pressure receiving surface B1 that receives the hydraulic pressure of the first output port of the main valve is equal to the opening area A2 of the first variable throttle of the main valve and the pilot valve. The amount of displacement of the main valve changes so as to be equal to the square of the ratio to the opening area B2 of the second variable aperture.

  The flow rate control in the flow rate control valve controls the flow rate of hydraulic fluid flowing from the inlet side flow path to the outlet side flow path by changing the opening amount of the main valve throttle according to the displacement amount of the main valve by operating the pilot valve. Is done. In this case, by controlling the opening amount of the pilot throttle of the pilot valve variably, the opening amount of the feedback throttle of the main valve changes corresponding to the change of the opening amount of the pilot throttle, and the flow rate passing through the main valve is changed to the pilot amount. Controlled by valve operation.

  Furthermore, the flow control valve has a function as a load check valve, and the load check valve can prevent a back flow from the outlet side flow path to the inlet side flow path. In this case, when the pressure of the inlet-side channel is lower than the outlet-side channel, the flow from the outlet-side channel to the inlet-side channel through the pilot throttle, the main valve back pressure chamber, the feedback throttle, and the check valve Is blocked by a check valve. Thereby, the pressure of the back pressure chamber of the main valve becomes equal to the pressure of the outlet side flow path, and a force in the valve closing direction due to the pressure of the back pressure chamber acts on the main valve. As a result, the main valve is displaced in the valve closing direction, and backflow from the outlet side channel to the inlet side channel can be prevented.

JP 06-193604 A (Patent No. 2987279)

  For example, as shown in FIG. 10 to be described later, in order to suppress variations in the minimum opening amount of the pilot throttle due to variations in manufacturing parts, the pilot throttle of the pilot valve is configured by two throttles, a variable throttle and a fixed throttle. It is possible. However, in this configuration, there is a possibility that the flow rate passing through the pilot throttle increases and the fluid force acting on the pilot throttle increases. Under the influence of this fluid force, the amount of axial displacement of the pilot operated pilot valve (pilot spool) with respect to the pilot pressure tends to vary, and the opening amount of the pilot throttle can be variably controlled with high accuracy. It can be difficult. This may make it difficult to variably control the flow rate from the inlet-side channel to the outlet-side channel by the main valve with high accuracy. In addition, the pilot valve, and thus the pilot housing, may be increased in size, resulting in an increase in manufacturing cost and a decrease in component mounting performance. Furthermore, the length of the flow path from the outlet-side flow path to the back pressure chamber is increased, which may reduce the responsiveness of the check valve.

  The purpose of the present invention is to control the flow rate from the inlet-side flow path to the outlet-side flow path with high accuracy, while suppressing the influence of fluid force, and to improve the responsiveness of the check valve. It is to provide a control valve.

  The flow control valve of the present invention includes a housing, a pilot housing, a main valve chamber provided in at least the housing of the housing and the pilot housing, a valve slidably provided in the main valve chamber, A main valve having a portion, a main valve seat provided on one end side of the main valve chamber, wherein the valve portion of the main valve communicates and shuts off when the valve portion of the main valve is separated and seated, and the main valve with respect to the main valve An inlet-side flow path for introducing a working fluid from the outside of the main valve chamber to the inside of the main valve chamber, and applying the pressure in a direction away from the valve seat; and when the main valve is separated from the main valve seat, An outlet-side flow path for deriving a working fluid from the inside of the main valve chamber to the outside of the main valve chamber and applying pressure in a direction away from the main valve seat to the main valve; and the other end of the main valve chamber Near the main valve seat with respect to the main valve A back pressure chamber that applies pressure in a direction; a feedback flow path that is provided in the main valve and that communicates the inlet side flow path and the back pressure chamber; and that is provided in the housing and the pilot housing; And a pilot flow path communicating with the outlet side flow path, and provided in the main valve, the inlet side flow path and the outlet side flow path according to a displacement of the main valve away from the main valve seat. A main valve throttle that increases the amount of opening between the feedback flow path and the back pressure chamber, and the feedback flow path with the displacement of the main valve away from the main valve seat. A feedback throttle that increases the amount of opening with the back pressure chamber, a pilot valve that is slidably provided on the pilot housing, and a pilot valve that is provided on the pilot valve, and that moves in accordance with displacement of the pilot valve. Pilot throttle that reduces or increases the opening amount of the lot flow channel, and provided in the feedback flow channel, allows the flow of the working fluid from the inlet flow channel to the back pressure chamber, and reverses the flow. A check valve for blocking, and variably controlling the flow rate from the inlet-side flow path to the outlet-side flow path by controlling the displacement amount of the main valve in accordance with the opening amount of the pilot throttle. The main valve controls the flow of the working fluid from the outlet side channel to the inlet side channel when having a flow rate control function and when the pressure of the inlet side channel is lower than the pressure of the outlet side channel. In the flow control valve having a load check function that is blocked by the check valve and the check valve, the flow control valve is provided between the back pressure chamber and the outlet side flow path, and the back pressure chamber and the outlet are not provided through the pilot flow path. Communicate with the side channel And a fixed throttle that fixes an opening amount between the back pressure chamber and the outlet-side flow path regardless of a displacement amount of the main valve, and the pilot throttle has a maximum displacement amount of the pilot valve. Before reaching the value or the minimum value, the opening amount of the pilot flow path is configured to be zero.

  According to the present invention, it is possible to variably control the flow rate from the inlet side flow path to the outlet side flow path with high accuracy while suppressing the influence of the fluid force, and to improve the responsiveness of the check valve.

It is a whole lineblock diagram showing the case where the flow control valve by an embodiment is applied to the hydraulic circuit of a hydraulic excavator. It is a longitudinal cross-sectional view which shows the flow control valve and direction control valve in FIG. FIG. 3 is an enlarged longitudinal sectional view showing a flow rate control valve in FIG. 2, that is, a part (III) in FIG. 2. It is a characteristic diagram which shows an example of the relationship between the pilot valve displacement amount by the embodiment, the main valve displacement amount, the pilot throttle opening amount, and the fixed throttle opening amount. It is a longitudinal cross-sectional view of the same position as FIG. 3 which shows the flow control valve by a 1st modification. It is a longitudinal cross-sectional view of the same position as FIG. 3 which shows the flow control valve by the 2nd modification. It is a longitudinal cross-sectional view which shows the flow control valve by a 3rd modification. It is a longitudinal cross-sectional view which shows the flow control valve by the 1st comparative example. It is a characteristic diagram which shows an example of the relationship between the pilot valve displacement amount by the 1st comparative example, pilot throttle opening amount, and the main valve displacement amount. It is a longitudinal cross-sectional view which shows the flow control valve by the 2nd comparative example. It is a characteristic diagram which shows an example of the relationship between the pilot valve displacement amount by the 2nd comparative example, pilot throttle opening amount, and the main valve displacement amount.

  Hereinafter, embodiments of the flow control valve of the present invention will be described in detail with reference to the accompanying drawings, taking as an example a case where the flow control valve is applied to a hydraulic circuit of a hydraulic excavator.

  1 to 4 show an embodiment. In FIG. 1, a hydraulic excavator 1 which is a representative example of a construction machine includes a self-propelled crawler-type lower traveling body 2, an upper revolving body 3 that is turnably mounted on the lower traveling body 2, and an upper revolving body. 3 is configured to include a multi-joint structure working device 4 that is provided on the front side of 3 so as to be capable of raising and lowering and performs excavation work and the like. In this case, the lower traveling body 2 and the upper swing body 3 constitute a vehicle body of the hydraulic excavator 1.

  The work device 4, also called a work machine or a front, includes, for example, a boom 5, an arm 6, a bucket 7 as a work tool, a boom cylinder 8 as a hydraulic actuator (hydraulic actuator) that drives them, an arm cylinder 9, and a bucket cylinder. (Working tool cylinder) 10. Based on the supply of pressure oil from the hydraulic pump 11, the work device 4 moves up and down as the cylinders 8, 9, and 10 that are hydraulic cylinders expand or contract. In FIG. 1, a hydraulic circuit mainly related to the boom cylinder 8 and the arm cylinder 9 is shown in order to avoid complication of the drawing.

  The main hydraulic pump 11 mounted on the upper swing body 3 of the hydraulic excavator 1 constitutes a hydraulic pressure source together with the tank 12. The hydraulic pump 11 is rotationally driven by a prime mover (not shown) such as a diesel engine, for example. The hydraulic pump 11 sucks the hydraulic oil in the tank 12 and discharges (supplies) the pressure oil toward the pump line 13 and the center bypass line 14. The pressure oil discharged to the pump line 13 and the center bypass line 14 is supplied to the boom cylinder 8 via the boom direction control valve 16 and supplied to the arm cylinder 9 via the arm direction control valve 18. Further, between the boom direction control valve 16 and the arm direction control valve 18 and the tank 12, for example, there is a tank line 15 for returning the return oil from the boom cylinder 8 and the arm cylinder 9 to the tank 12 side. Is provided.

  Here, in the middle of the pump line 13, branch lines 13 </ b> A and 13 </ b> B are provided. One branch pipe 13 </ b> A is connected to a high-pressure side port of the arm direction control valve 18 (that is, a later-described outlet-side flow path 27 shown in FIG. 2) via a later-described flow rate control valve 33. The other branch pipe 13B is connected to a high-pressure side port of a boom direction control valve 16, which will be described later. The pump line 13 and the tank line 15 are also connected to the bucket cylinder 10 and the like via another branch line, another direction control valve (both not shown), and the like.

  A boom direction control valve 16 (hereinafter referred to as a boom control valve 16), which is a direction control valve for the boom cylinder 8, has left and right hydraulic pilot portions 16A and 16B, and is always in a neutral position (i.e. ). The boom control valve 16 is supplied with pilot pressure from, for example, a boom lever operating device (not shown), which is a hydraulic pilot type operating valve, to the left and right hydraulic pilot portions 16A and 16B. Switching from the neutral position (A) to the switching position (B) and (C).

  The pair of actuator pipes 17 </ b> A and 17 </ b> B is provided between the boom cylinder 8 and the boom control valve 16. One actuator 17 </ b> A connects the bottom side oil chamber (not shown) of the boom cylinder 8 to one pressure oil inflow / outflow port of the boom control valve 16. The other actuator pipe 17 </ b> B connects the rod side oil chamber (not shown) of the boom cylinder 8 to the other pressure oil inflow / outflow port of the boom control valve 16.

  An arm directional control valve 18 (hereinafter referred to as an arm control valve 18), which is a directional control valve for the arm cylinder 9, has left and right hydraulic pilot portions 18A and 18B. ). The arm control valve 18 is supplied with pilot pressure from, for example, an arm lever operating device (not shown), which is a hydraulic pilot type operating valve, to the left and right hydraulic pilot portions 18A and 18B. Switching from the neutral position (A) to the switching position (B) and (C).

  The pair of actuator pipes 19 </ b> A and 19 </ b> B is provided between the arm cylinder 9 and the arm control valve 18. One actuator pipe 19A connects the bottom side oil chamber (not shown) of the arm cylinder 9 to one pressure oil inflow / outflow port of the arm control valve 18 (that is, the outflow / inflow passage 28A shown in FIG. 2). To do. The other actuator pipe 19B connects the rod side oil chamber (not shown) of the arm cylinder 9 to the other pressure oil inflow / outflow port of the arm control valve 18 (that is, the outflow / inflow passage 28B shown in FIG. 2). To do.

  When the arm control valve 18 is switched from the neutral position (A) to the switching position (B), the pressure oil from the hydraulic pump 11 is branched 13A, a flow control valve 33 (described later), the arm control valve 18, an actuator. The oil is supplied to the bottom side oil chamber of the arm cylinder 9 through the pipe line 19A, and the pressure oil in the rod side oil chamber is discharged to the tank 12 through the actuator pipe line 19B, the arm control valve 18, and the tank pipe line 15. . Thereby, the arm cylinder 9 extends by the pressure oil supplied to the bottom side oil chamber, and swings the arm 6 downward.

  When the arm control valve 18 is switched from the neutral position (A) to the switching position (C), the pressure oil from the hydraulic pump 11 is branched from the branch line 13A, the flow control valve 33, the arm control valve 18, and the actuator line. The pressure oil in the bottom side oil chamber is supplied to the tank 12 via the actuator pipe 19 </ b> A, the arm control valve 18, and the tank pipe 15. As a result, the arm cylinder 9 is contracted by the pressure oil supplied to the rod side oil chamber, and the arm 6 is lifted upward.

  The relief valve 20 is a set pressure variable type relief valve. The relief valve 20 is provided between the pump line 13 and the center bypass line 14 and the tank line 15. The relief valve 20 opens, for example, when the pressure in the pump line 13 rises above a set pressure, and relieves excess pressure at this time to the tank line 15 side. The relief valve 20 includes a pressure setting spring 20A, a pilot oil chamber 20B, and the like, and the set pressure of the pressure setting spring 20A changes according to the pilot pressure supplied to the pilot oil chamber 20B from the outside. As a result, the relief valve 20 has a configuration in which the relief set pressure can be adjusted in multiple stages of two stages or three or more stages between the low pressure setting and the high pressure setting.

  The control valve device 21 includes an arm control valve 18 and a flow rate control valve 33 described later. As shown in FIG. 2, the control valve device 21 has a valve casing 22 common to the arm control valve 18 and the flow control valve 33. In this case, the valve casing 22 includes a housing 23 that houses the spool 29 of the arm control valve 18 and the main valve 43 of the flow control valve 33, and a pilot housing 36 that houses the main valve 43 and the pilot valve 55 of the flow control valve 33. It is comprised including. The housing 23 and the pilot housing 36 are separately formed as separate parts. And by attaching the pilot housing 36 to the housing 23, the valve casing 22 which becomes one (integral or common) casing is comprised.

  Next, the arm control valve 18 of the control valve device 21 will be described. FIG. 2 shows the arm control valve 18 in the neutral position (A).

  The arm control valve 18 is a spool valve device that controls the direction of pressure oil supplied from the hydraulic pump 11 to the arm cylinder 9. The arm control valve 18 includes a housing 23, a spool sliding hole 24, an inlet side passage 25, an outlet side passage 27, a pair of inflow / outflow passages 28A and 28B, a spool 29, a left and a right The lids 30 </ b> A and 30 </ b> B, the stopper 31, and the spring 32 are included. The housing 23 constitutes the valve casing 22 of the control valve device 21 together with the pilot housing 36. The housing 23 is formed with a spool sliding hole 24, an inlet-side channel 25, an outlet-side channel 27, and a pair of inflow / outflow passages 28A and 28B.

  The spool sliding hole 24 extends in a straight line through the housing 23 in the left and right directions (left and right directions in FIG. 2, the axial direction in which a spool 29 described later slides). On the peripheral wall side of the spool sliding hole 24, first annular oil grooves 24A and 24B, second annular oil grooves 24C and 24D, and third annular oil grooves 24E and 24F are formed. The first annular oil grooves 24A and 24B are provided on the center side in the axial direction of the spool sliding hole 24 so as to be separated from each other in the left and right directions. The second annular oil grooves 24C and 24D are provided at positions on the axially outer side of the spool sliding hole 24 with respect to the first annular oil grooves 24A and 24B and spaced apart from each other in the left and right directions. The third annular oil grooves 24E and 24F are provided at positions on the outer side in the axial direction of the spool sliding hole 24 with respect to the second annular oil grooves 24C and 24D and spaced apart from each other in the left and right directions.

  The first annular oil grooves 24A and 24B communicate with each other by an outlet-side flow passage 27 formed in an inverted U shape as a whole. The first annular oil grooves 24A and 24B are communicated with and blocked from the second annular oil grooves 24C and 24D when the spool 29 is displaced leftward and rightward from the neutral position shown in FIG. The second annular oil grooves 24C, 24D are always in communication with the pair of actuator conduits 19A, 19B via the left and right inflow / outflow passages 28A, 28B. The third annular oil grooves 24E and 24F are always in communication with the tank 12 via the tank conduits 15. The third annular oil grooves 24E and 24F are communicated with and blocked from the second annular oil grooves 24C and 24D when the spool 29 is displaced leftward and rightward from the neutral position shown in FIG.

  The inlet-side flow path 25 is provided at a position spaced from the spool sliding hole 24 in the radial direction. In this case, the inlet-side flow path 25 extends along a direction (front and back directions in FIG. 2) orthogonal to the spool sliding hole 24. The inlet side flow path 25 is connected to the hydraulic pump 11 via the pump pipe line 13 (more specifically, the branch pipe line 13A). The outlet side channel 27 intersects with the inlet side channel 25 at the position of the communication hole 26 and extends in an inverted U shape as a whole. The outlet-side flow passage 27 communicates with the first annular oil grooves 24A and 24B that are provided apart from each other.

  The communication hole 26 is disposed at a position facing a later-described valve body sliding hole 34 with the outlet-side flow path 27 interposed therebetween. The communication hole 26 communicates the inlet side flow path 25 with the outlet side flow path 27 so as to intersect. The communication hole 26 constitutes a main valve chamber 42 together with a later-described valve body sliding hole 34 and a recess 37 of the pilot housing 36. A tapered main valve seat 46 as an annular valve seat, on which a later-described main valve 43 is seated, is provided at the intersection of the outlet side flow path 27 and the communication hole 26.

  The pair of inflow / outflow passages 28 </ b> A and 28 </ b> B are spaced apart in the left and right directions of the housing 23 so as to sandwich the outlet side flow path 27 and the valve body sliding hole 34. The pair of inflow / outflow passages 28 </ b> A and 28 </ b> B constitute a pressure oil inflow / outflow port of the arm control valve 18. That is, the pair of inflow / outflow passages 28A and 28B are connected to the arm cylinder 9 (the rod side oil chamber and the bottom side oil chamber) via the actuator pipes 19A and 19B.

  The spool 29 is inserted into the spool sliding hole 24 of the housing 23. The spool 29 is slidably displaced in the left and right directions in the spool sliding hole 24 in accordance with the pilot pressure supplied to the hydraulic pilot portions 18A and 18B from the outside. As a result, the arm control valve 18 shown in FIG. 1 is switched from the neutral position (A) to the left and right switching positions (B) and (C).

  As shown in FIG. 2, the spool 29 selectively communicates the second annular oil grooves 24C and 24D with one of the first annular oil grooves 24A and 24B and the third annular oil grooves 24E and 24F. , Switching lands 29A and 29B to be shut off. A plurality of notches 29A1 and 29B1 for finely adjusting the flow rate of the pressure oil are formed in the switching lands 29A and 29B so as to be spaced apart from each other in the circumferential direction.

  Here, when the spool 29 is slidably displaced in the left direction of FIG. 2, the switching land 29A of the spool 29 causes the first annular oil groove 24A to communicate with the second annular oil groove 24C. At the same time, the switching land 29B of the spool 29 blocks the first annular oil groove 24B from the second annular oil groove 24D, and communicates the second annular oil groove 24D with the third annular oil groove 24F. Let Thus, the arm control valve 18 is switched from the neutral position (A) shown in FIG. 1 to the right switching position (C).

  On the other hand, when the spool 29 is slid to the right in FIG. 2, the switching land 29B of the spool 29 causes the first annular oil groove 24B to communicate with the second annular oil groove 24D. At the same time, the switching land 29A of the spool 29 shuts off the first annular oil groove 24A from the second annular oil groove 24C and communicates the second annular oil groove 24C with the third annular oil groove 24E. Let As a result, the arm control valve 18 is switched from the neutral position (A) shown in FIG. 1 to the left switching position (B).

  The left and right lids 30 </ b> A and 30 </ b> B constitute an arm control valve 18 together with the spool 29. The lids 30 </ b> A and 30 </ b> B are attached to the housing 23 so as to be located on both sides in the axial direction (left and right directions) of the spool sliding hole 24. The lids 30 </ b> A and 30 </ b> B close the both ends of the spool sliding hole 24. The left lid 30A is formed longer than the right lid 30B, and a centering spring 32 is provided in the left lid 30A. Hydraulic pilot portions 18A and 18B are provided inside the lid bodies 30A and 30B, and pilot pressure is supplied to these hydraulic pilot portions 18A and 18B from an operation valve (lever operation device). The spool 29 of the arm control valve 18 is slidably displaced in the spool sliding hole 24 in the left and right directions in FIG. 2 according to the pilot pressure at this time.

  The stopper 31 is provided integrally with the spool 29 on the left side of the spool 29. The stopper 31 is disposed in the lid body 30A so as to be slidable and has a shaft portion 31A extending in the axial direction in the lid body 30A. The stopper 31 regulates the stroke end of the spool 29 when the spool 29 is slid in the left direction in FIG.

  The spring 32 is a centering spring for holding the spool 29 in a neutral position. The spring 32 is located on the outer peripheral side of the shaft portion 31 </ b> A of the stopper 31 and is disposed in a state where an initial load is applied in advance between the end surface of the spool 29 and the stopper 31. The spring 32 holds the spool 29 in the neutral position when the pilot pressure from the hydraulic pilot portions 18A and 18B is reduced to the tank pressure level.

  Next, the flow control valve 33 of the control valve device 21 will be described. 2 and 3 show the flow rate control valve 33 in the state of the maximum flow rate at which the main valve 43 is most opened.

  The flow rate control valve 33 is a poppet valve device that adjusts the flow rate of the pressure oil supplied to the arm cylinder 9. The flow rate control valve 33 includes a housing 23, a pilot housing 36, a main valve chamber 42, a main valve 43, a main valve seat 46, an inlet side channel 25, an outlet side channel 27, and a back pressure chamber 47. A feedback flow path 49, a pilot flow path 50, a main valve throttle 53, a feedback throttle 54, a pilot valve 55, a pilot throttle 56, and a check valve 62.

  The housing 23 forms a casing of the flow control valve 33 together with the pilot housing 36. In the housing 23, a valve body sliding hole 34 and a branch passage 35 are formed in addition to the inlet-side flow path 25, the communication hole 26, and the outlet-side flow path 27.

  The valve body sliding hole 34 is disposed on the opposite side of the inlet-side channel 25 with the communication hole 26 and the outlet-side channel 27 interposed therebetween, and is formed as a stepped hole. The valve body sliding hole 34 extends between the pilot housing 36 and the outlet-side flow path 27 in a direction perpendicular to the spool sliding hole 24 (upward and downward in FIG. 2). The valve body sliding hole 34 constitutes a main valve chamber 42 together with the communication hole 26 and the recess 37 of the pilot housing 36. And in the main valve chamber 42, the main valve 43 is inserted (fitted) so that a displacement is possible.

  The branch passage 35 is an oil passage branched from the middle of the outlet side passage 27. The branch passage 35 is always in communication with the second passage 40 on the pilot housing 36 side. The branch passage 35 constitutes the pilot passage 50 together with the second passage 40 and the first passage 39 which is another passage provided in the pilot housing 36.

  The pilot housing 36 constitutes a casing (valve casing 22) of the flow control valve 33 together with the housing 23. The pilot housing 36 is provided on the outer surface of the housing 23 so as to close the valve body sliding hole 34 of the housing 23 from the outside. The pilot housing 36 includes a recess 37 in which a later-described main valve 43 and a valve spring 48 are accommodated, a valve accommodation hole 38 in which a later-described pilot valve 55 is accommodated, and a space between the valve accommodation hole 38 and the recess 37. Is connected to and cut off from the first passage 39 by a pilot valve 55 extending obliquely between the branch passage 35 of the housing 23 and the valve housing hole 38. And a pilot pressure supply / exhaust port 41 are provided. The supply / discharge port 41 is connected to a pilot chamber 57 defined by the inner surface of the valve accommodating hole 38 and the pilot valve 55.

  The main valve chamber 42 is provided in the housing 23 and the pilot housing 36. The main valve chamber 42 is constituted by the valve body sliding hole 34 and the communication hole 26 of the housing 23 and the recess 37 of the pilot housing 36, and accommodates the main valve 43 therein. Thereby, the main valve chamber 42 is provided over both the housing 23 and the pilot housing 36.

  The main valve 43 is slidably provided in the main valve chamber 42. The main valve 43 is a valve body of the flow control valve 33 and has a valve portion 44D. In this case, the main valve 43 is provided with a stepped valve member 44 inserted into the valve body sliding hole 34 and screwed to one side in the axial direction of the valve member 44, and a check valve 62 described later is provided as a valve. A valve holding member 45 that is displaceably held with respect to the member 44 is included. The valve holding member 45 includes a spring receiving portion 45A that supports the valve spring 48 in a contracted state between the valve spring 48 and the recess 37 (the bottom thereof) of the pilot housing 36, and a valve member 44 (described later). A holding cylinder portion 45B that holds the check valve 62 in a displaceable manner while being screwed into the upper hole side 44G). In this case, a check valve 62 and a spring 63 are accommodated inside the holding cylinder portion 45B.

  The valve member 44 includes a large-diameter portion 44A that is slidably inserted into the valve body sliding hole 34, a small-diameter cylindrical portion 44B provided on one side in the axial direction of the large-diameter portion 44A, and a large-diameter portion. The valve portion 44D is integrally formed on the other side in the axial direction of 44A via a reduced diameter portion 44C and the outer peripheral side is attached to and detached from the main valve seat 46 of the housing 23, and from the other side (tip side) of the valve portion 44D. A cylindrical protrusion 44E that protrudes in the axial direction toward the inlet-side flow path 25 is configured. In this case, the valve portion 44D is also called a seat portion, and is provided in the main valve 43 (valve member 44). The valve portion 44 </ b> D contacts (sits) the main valve seat 46, thereby blocking the flow of the working fluid between the inlet-side channel 25 and the outlet-side channel 27.

  In addition, the valve member 44 is checked from the inner peripheral side of the cylindrical projecting portion 44E into the reduced diameter portion 44C, the large diameter portion 44A, and the small diameter cylindrical portion 44B toward one side (upper side) in the axial direction. A stepped hole 44G in which a valve seat 44F for the valve 62 is formed, a radial hole 44H extending in the radial direction of the stepped hole 44G, and a feedback throttle 54 described later are provided. The stepped hole 44G communicates with the inlet-side flow path 25 through the inner peripheral side of the cylindrical protrusion 44E. The radial hole 44H communicates with a back pressure chamber 47, which will be described later, via a feedback throttle 54. As a result, the stepped hole 44G and the radial hole 44H constitute a feedback flow path 49.

  In addition, a main valve throttle 53 including a plurality of radial through holes is provided in the cylindrical protrusion 44E of the valve member 44. As a result, the flow rate of the pressure oil flowing from the inlet side channel 25 to the outlet side channel 27 via the communication hole 26 (that is, the opening area of the communication hole 26 with respect to the outlet side channel 27) is reduced by the main valve throttle 53. Adjusted. Further, a fixed throttle 64 described later is provided on the outer peripheral side of the large-diameter portion 44 </ b> A of the valve member 44.

  The main valve seat 46 is provided on one end side (inlet side flow path 25 side) of the main valve chamber 42. In other words, the main valve seat 46 is provided at the intersection of the outlet 23 and the communication hole 26 in the housing 23, and is configured as a tapered annular valve seat. The main valve seat 46 communicates and shuts off the working fluid as the valve portion 44D of the main valve 43 separates and seats.

  The inlet-side channel 25 is provided in the housing 23 and is connected to the discharge side of the hydraulic pump 11. The inlet-side flow path 25 applies pressure in a direction away from the main valve seat 46 (opening direction) to the main valve 43 based on pressure oil (working fluid) supplied from the hydraulic pump 11. At the same time, the inlet-side flow path 25 introduces the working fluid into the main valve chamber 42 from the outside of the main valve chamber 42 (the hydraulic pump 11 side). The inlet side flow path 25 faces the main valve seat 46.

  The outlet side flow path 27 is provided in the housing 23 and is connected to the spool sliding hole 24 of the arm control valve 18. When the main valve 43 is separated from the main valve seat 46, the outlet-side flow path 27 extends from the inside of the main valve chamber 42 (communication hole 26 side) to the outside of the main valve chamber 42 (spool sliding hole of the arm control valve 18). The working fluid is led out to the 24 side, more specifically, to the arm cylinder 9 side. At the same time, the outlet-side flow path 27 applies a pressure in the direction away from the main valve seat 46 to the main valve 43 (the valve opening direction). The outlet side flow path 27 also faces the main valve seat 46.

  The back pressure chamber 47 is provided on the other end side of the main valve chamber 42 (on the side opposite to the inlet side flow path 25). The back pressure chamber 47 applies pressure in a direction (valve closing direction) approaching the main valve seat 46 to the main valve 43. That is, the back pressure chamber 47 is a control pressure chamber that variably controls the amount of displacement (lift amount) of the main valve 43, and is formed between the recess 37 of the pilot housing 36 and the main valve 43. The back pressure chamber 47 is always in communication with the first passage 39 of the pilot housing 36.

  The valve spring 48 is located in the back pressure chamber 47 and is disposed between the main valve 43 (the valve holding member 45 thereof) and the recess 37 (the bottom thereof) of the pilot housing 36. The valve spring 48 is configured by using a coil spring or the like, and normally biases the main valve 43 (valve holding member 45) in the valve closing direction. The main valve 43 is also pressed in the valve closing direction by back pressure (control pressure) generated in the back pressure chamber 47.

  The feedback flow path 49 is provided inside the main valve 43. That is, the feedback flow path 49 includes a stepped hole 44G and a radial hole 44H of the main valve 43 (valve member 44). In this case, the radial hole 44 </ b> H communicates with the back pressure chamber 47 via the feedback throttle 54. Thus, the feedback flow path 49 communicates the inlet-side flow path 25 and the back pressure chamber 47.

  The pilot flow path 50 is provided in the housing 23 and the pilot housing 36. That is, the pilot flow path 50 is configured by the branch passage 35 of the housing 23, the first passage 39 and the second passage 40 of the pilot housing 36. Thus, the pilot flow path 50 communicates the back pressure chamber 47 and the outlet side flow path 27. In this case, the first passage 39 constitutes a pilot throttle upstream pipe 51 serving as a pipe on the upstream side of the pilot throttle 56, and the second passage 40 and the branch passage 35 are downstream of the pilot throttle 56. The pilot throttle downstream pipe 52 which becomes this pipe is constituted.

  The main valve throttle 53 is provided on the main valve 43. That is, the main valve throttle 53 is configured by a radial through hole provided in the cylindrical protrusion 44E of the valve member 44. The main valve throttle 53 is displaced in the direction away from the main valve seat 46 of the main valve 43 (displacement in the upward and downward directions in FIGS. 2 and 3) and the inlet-side flow path 25 and the outlet-side flow path 27. Increase the amount of opening between.

  The feedback throttle 54 is provided between the feedback flow path 49 and the back pressure chamber 47. In the embodiment, the feedback throttle 54 is provided as a variable throttle on the outer peripheral surface side of the main valve 43 (the large diameter portion 44A of the valve member 44). The feedback throttle 54 increases the amount of opening between the feedback flow path 49 and the back pressure chamber 47 with the displacement of the main valve 43 in the direction away from the main valve seat 46 (the valve opening direction).

  The pilot valve 55 is slidably provided on the pilot housing 36. That is, the pilot valve 55 is slidably inserted (fitted) into the valve housing hole 38 of the pilot housing 36. The pilot valve 55 is configured as a spool valve body having a pilot throttle 56. The pilot valve 55 is displaced by introducing a working fluid into the pilot chamber 57 and pressurizing it. Further, along with the displacement of the pilot valve 55, working fluid in a drain chamber 59 described later is discharged from a drain port (not shown).

  The pilot throttle 56 is provided on the pilot valve 55. That is, the pilot throttle 56 is provided as a variable throttle on the outer peripheral surface side of the pilot valve 55. The pilot throttle 56 reduces the opening amount of the pilot flow path 50 with the displacement of the pilot valve 55. That is, as the pilot throttle 56 is supplied with pressure oil (pilot pressure) to the pilot chamber 57, the pilot valve 55 advances to one side in the axial direction (to the left in FIGS. 2 and 3 and to the right in the right direction). The opening amount of the pilot flow path 50 is decreased. In this case, for example, the pilot throttle 56 can be configured as a notch that becomes deeper as it travels to one side in the axial direction (away from the pilot chamber 57). Further, as will be described later, the pilot throttle 56 according to the embodiment is configured such that the opening amount of the pilot flow path 50 becomes zero before the displacement amount of the pilot valve 55 reaches the maximum value (rightmost side). .

  The lid 58 is positioned on one side of the valve housing hole 38 in the axial direction and is attached to the pilot housing 36 by screwing. The lid 58 defines a drain chamber (spring chamber) 59 on one side of the pilot valve 55 by closing one side of the valve accommodation hole 38. A spring 60 is provided between the lid 58 and the pilot valve 55 in a compressed state. The spring 60 urges the pilot valve 55 in the valve opening direction via the washer 61.

  When the pilot valve 55 is disposed at the communication position (a) shown in FIG. 1 by the spring 60, the pilot valve 55 communicates between the first and second passages 39 and 40, which are the pilot flow path 50, via the pilot throttle 56. Let At this time, the back pressure chamber 47 of the main valve 43 communicates with the outlet side passage 27 via the first and second passages 39 and 40 and the branch passage 35 on the housing 23 side, and is equal to the outlet side passage 27. Kept in pressure. As a result, the main valve 43 is opened to the fully open position.

  On the other hand, the pilot valve 55 has a predetermined pressure value in which a pilot pressure as an external command pressure supplied to the pilot chamber 57 via the supply / discharge port 41 from a remote control valve (not shown) for external command is determined in advance. When it rises to the above, it slides and displaces against the spring 60, and the first and second passages 39, 40 are blocked. As a result, the pilot valve 55 switches from the communication position (a) shown in FIG. 1 to the blocking position (b) against the spring 60. At this time, the back pressure chamber 47 of the main valve 43 is blocked with respect to the second passage 40. Thereby, the main valve 43 becomes the minimum opening position.

  The check valve 62 is provided in the feedback flow path 49. That is, the check valve 62 is accommodated between the valve member 44 and the valve holding member 45. The check valve 62 is slidably inserted into the holding cylinder portion 45B of the valve holding member 45, and is normally biased by a spring 63 so as to be seated on the valve seat 44F of the valve member 44. That is, the check valve spring 63 urges the check valve 62 in the valve closing direction. The check valve 62 allows the flow of the working fluid from the inlet side flow path 25 to the back pressure chamber 47 and blocks (blocks) the flow opposite to this. That is, the check valve 62 opens so as to separate from the valve seat 44F against the spring 63 when the pressure in the inlet-side flow path 25 acts from the cylindrical projecting portion 44E side of the valve member 44. As a result, the pressure oil in the inlet-side channel 25 is supplied to the back pressure chamber 47 via the stepped hole 44G and the radial hole 44H of the valve member 44 and the feedback throttle 54. Thus, the check valve 62 allows the pressure oil to flow through the main valve 43 from the inlet-side flow path 25 toward the back pressure chamber 47, and prevents the reverse flow. That is, the check valve 62 prevents the oil in the back pressure chamber 47 from flowing toward the stepped hole 44G and the inlet-side channel 25 through the radial hole 44H of the valve member 44 and the like. .

  The flow control valve 33 configured in this manner has a flow control function and a load check function. That is, the flow control valve 33 controls the displacement amount (lift amount, that is, opening area) of the main valve 43 in accordance with the opening amount of the pilot throttle 56, thereby moving from the inlet side flow path 25 to the outlet side flow path 27. Has a flow rate control function for variably controlling the flow rate (flow rate of the pressure oil flowing through the arm control valve 18). At the same time, the flow rate control valve 33 is a working fluid (oil) from the outlet side channel 27 to the inlet side channel 25 when the pressure of the inlet side channel 25 is lower than the pressure of the outlet side channel 27. Has a load check function for blocking the flow of the gas by the main valve 43 and the check valve 62.

  Here, prior to the description of the features of the flow control valve 33 of the embodiment, the flow control valve 101 according to the first comparative example shown in FIG. 8 will be described. The flow control valve 101 in FIG. 8 differs from the flow control valve 33 according to the embodiment in the configuration of the main valve 102 and the pilot valve 103. Specifically, the main valve 43 of the embodiment is provided with a fixed throttle 64 to be described later. On the other hand, the fixed valve 64 is not provided in the main valve 102 of the first comparative example. Further, the pilot throttle 104 of the pilot valve 103 of the first comparative example is configured as a variable throttle similarly to the pilot throttle 56 of the pilot valve 55 of the embodiment. However, in the pilot throttle 104 of the first comparative example, even if the displacement amount of the pilot valve 103 reaches the maximum value (even if the pilot valve 103 is displaced to the rightmost side in FIG. 8), the opening amount of the pilot flow path 50 Is different from the pilot diaphragm 56 of the embodiment in that it does not become zero.

  Similarly to the flow control valve 33 according to the embodiment, the flow control valve 101 according to the first comparative example also controls the amount of displacement of the main valve 102 by variably controlling the opening amount of the pilot throttle 104. The That is, by variably controlling the opening amount of the pilot throttle 104, the opening amount of the feedback throttle 54 provided in the main valve 102 changes corresponding to the change of the opening amount of the pilot throttle 104, and the displacement of the main valve 102 is changed. The amount is controlled. Thereby, the opening amount of the main valve throttle 102B provided in the main valve 102 is variably controlled, and the flow rate from the inlet side flow path 25 to the outlet side flow path 27 can be controlled to a desired value.

  Here, consider a case where the flow rate from the inlet-side channel 25 to the outlet-side channel 27 is controlled to a minimum. In this case, the opening amount of the pilot throttle 56 (the opening amount of the pilot flow path 50) is minimized by maximizing the pressure of the pilot chamber 57 of the pilot valve 103 and maximizing the displacement amount of the pilot valve 103. To do. Thereby, the displacement amount of the main valve 102 can be minimized, and the opening amount of the main valve throttle 53 can be minimized. At this time, for example, due to manufacturing variations of parts, a relative variation in the axial direction occurs between the “pilot throttle 104” and the “pilot housing 36 in which the pilot valve 103 is slidably fitted”. There is a possibility that the minimum opening amount of the diaphragm 104 varies. As the minimum opening amount of the pilot throttle 104 varies, the amount of displacement of the main valve 102 varies, so that the flow rate from the inlet-side channel 25 to the outlet-side channel 27 may also vary.

  FIG. 9 shows an example of the relationship among “displacement amount of pilot valve 103”, “opening amount of pilot throttle 104”, and “displacement amount of main valve 102” by flow control valve 101 (FIG. 8) of the first comparative example. FIG. The solid line in FIG. 9 indicates the characteristic of manufacturing variation “none”, and the broken line in FIG. 9 indicates the characteristic of manufacturing variation “present”. As is clear from FIG. 9, the flow control valve 101 of the first comparative example maximizes the displacement of the pilot valve 103 by increasing the pressure in the pilot chamber 57 of the pilot valve 103 (that is, the opening amount of the pilot throttle 104). ) To the minimum), the amount of displacement of the main valve varies with manufacturing variations, and the flow rate from the inlet side flow path 25 to the outlet side flow path 27 may vary. In order to drive the hydraulic actuator (arm cylinder 9) with high accuracy, high-accuracy flow rate control is required, and such a variation in flow rate is not preferable.

  On the other hand, in order to suppress such variation in flow rate, it is conceivable that the pilot throttle is composed of a “variable throttle” and a “fixed throttle”. FIG. 10 shows a flow control valve 111 according to the second comparative example. The flow rate control valve 111 of the second comparative example shown in FIG. 10 includes a variable throttle 113A configured such that the pilot throttle 113 of the pilot valve 112 can have an opening amount of 0 (zero), and the displacement of the pilot valve 112. Regardless of this, the fixed aperture 113B has a constant aperture amount. This point is different from the flow control valve 101 of the first comparative example.

  Such a flow control valve 111 of the second comparative example has an axial relative difference between the “pilot throttle 113” and the “pilot housing 36 in which the pilot valve 112 is slidably fitted” due to manufacturing variations of parts. Even if the variation occurs, the opening amount of the pilot throttle 113 is restricted only by the fixed throttle 113B at the maximum displacement position of the pilot valve 112. For this reason, it can suppress that the opening amount in the maximum displacement position of the pilot valve 112 can suppress, and can control the flow volume from the inlet side flow path 25 to the outlet side flow path 27 to the minimum with high precision.

  FIG. 11 shows an example of the relationship between “displacement amount of pilot valve 112”, “opening amount of pilot throttle 113”, and “displacement amount of main valve 102” by flow control valve 111 (FIG. 10) of the second comparative example. FIG. The solid line in FIG. 11 indicates the characteristic of “manufacturing variation“ none ”, and the broken line in FIG. 11 indicates the characteristic of manufacturing variation“ present ”. As is apparent from FIG. 11, the flow control valve 111 of the second comparative example maximizes the pressure in the pilot chamber 57 of the pilot valve 112 to maximize the displacement of the pilot valve 112 (that is, the opening of the pilot throttle 113). The amount of main valve displacement can be regulated as desired regardless of manufacturing variations. Thereby, it can suppress that the flow volume from the inlet side flow path 25 to the outlet side flow path 27 varies.

  However, in the case of the flow rate control valve 111 of the second comparative example, two types of throttles (variable throttle 113A and fixed throttle 113B) are formed in the pilot throttle 113. For this reason, there is a possibility that the flow rate passing through the pilot throttle 113 increases and the fluid force (force applied in the axial direction of the pilot valve 112) acting on the pilot throttle 113 increases. Due to the influence of the fluid force, it becomes difficult to control the opening amount of the pilot throttle 113 with high accuracy, and as a result, the flow rate from the inlet side flow channel 25 to the outlet side flow channel 27 can be changed with high accuracy. It can be difficult to control. Furthermore, in order to form the two types of throttles 113A and 113B in the pilot throttle 113, it may be necessary to increase the outer diameter of the pilot valve 112. As a result, the pilot housing becomes larger, which may increase the manufacturing cost and decrease the component mounting property.

  Next, consider the load check function of the flow control valves 101 and 111 according to the first comparative example and the second comparative example. The flow rate control valves 101 and 111 use the “main valve 102 provided with the valve portion 102 </ b> A” and the “check valve 62 provided inside the main valve 102” from the outlet side channel 27 to the inlet side channel. Prevent backflow to 25. Specifically, when the pressure of the inlet-side channel 25 is lower than the outlet-side channel 27, the outlet-side channel 27 → the pilot throttle downstream pipe 52 → the pilot throttles 104 and 113 → the pilot throttle upstream pipe 51 → A flow occurs in the back pressure chamber 47 → the feedback throttle 54 → the check valve 62 → the inlet-side flow path 25, but this flow is blocked by the check valve 62. As a result, the pressures in the back pressure chamber 47 and the outlet side flow path 27 become equal, and the force in the valve closing direction due to the pressure in the back pressure chamber 47 acts on the main valve 102 and is displaced in the valve closing direction. As a result, the valve portion 102A of the main valve 102 is seated on the main valve seat 46 of the housing 23, whereby the flow of the outlet side flow path 27 → the main valve throttle 102B → the inlet side flow path 25 is blocked.

  However, in the case of the flow rate control valves 101 and 111 according to the first comparative example and the second comparative example, when the flow is generated from the outlet side flow path 27 to the back pressure chamber 47, the pilot throttle upstream pipe 51 and the pilot throttle downstream. Since the pipe line 52 is interposed, the length of the flow path from the outlet side flow path 27 to the back pressure chamber 17 becomes long. Such an increase in the length of the flow path leads to a delay in the response of the check valve 62 until the load check function is exhibited, and thus a delay in the response of the main valve 102 (main valve throttle 102B). there is a possibility. And when this delay is remarkable, there exists a possibility of producing a backflow.

  Therefore, in the embodiment, it is possible to achieve both “to control the flow rate from the inlet-side channel 25 to the outlet-side channel 27 variably with high accuracy” and “to improve the responsiveness of the check valve 62”. The following configuration is adopted. That is, as shown in FIGS. 2 and 3, in the embodiment, a fixed throttle 64 is provided between the back pressure chamber 47 and the outlet side flow path 27. In this case, the fixed throttle 64 communicates the back pressure chamber 47 and the outlet side channel 27 without passing through the pilot channel 50 (that is, the pilot throttle upstream pipe 51 and the pilot throttle downstream pipe 52). is there. At the same time, the fixed throttle 64 fixes (makes constant) the opening amount between the back pressure chamber 47 and the outlet side flow passage 27 regardless of the displacement amount of the main valve 43.

  Therefore, in the embodiment, a plurality or a single main valve side communication groove 64A extending in the axial direction of the main valve 43 is provided on the outer peripheral surface of the main valve 43 (the outer peripheral surface of the large diameter portion 44A of the valve member 44). It has been. The main valve side communication groove 64 </ b> A is provided over the entire axial direction of the large diameter portion 44 </ b> A of the valve member 44. The fixed throttle 64 is constituted by the main valve side communication groove 64 </ b> A and the wall surface of the main valve chamber 42.

  Furthermore, in the embodiment, the pilot diaphragm 56 is configured by a variable diaphragm. In this case, the pilot throttle 56 has a reduced opening amount of the pilot flow path 50 as the pilot valve 55 is displaced. At the same time, in the pilot throttle 56, the opening amount of the pilot flow path 50 becomes zero before the displacement amount of the pilot valve 55 reaches the maximum value. That is, the pilot valve 55 makes a connection between the pilot throttle upstream pipe 51 and the pilot throttle downstream pipe 52 before the displacement reaches the maximum value by proceeding from the left side to the right side in FIGS. Cut off. The maximum value of the displacement amount of the pilot valve 55 corresponds to the position where the pilot valve 55 is most displaced from the initial position based on the supply of the pilot pressure to the pilot chamber 57. Further, “the opening amount is zero” includes not only the state where the opening amount is completely zero but also the state where the opening amount is not completely zero but is substantially zero due to an inevitable gap or the like. In other words, “the opening amount is zero” is a range in which the displacement amount of the main valve 43 can be controlled with high accuracy, and allows a state that is not completely zero.

  The control valve device 21 including the flow control valve 33 according to the embodiment has the above-described configuration, and the operation thereof will be described next.

  First, the pressure oil discharged from the hydraulic pump 11 flows from the branch line 13A of the pump line 13 to the inlet side flow path 25 of the housing 23, the main valve 43 of the flow control valve 33, and the communication hole 26 (the main valve). It flows through the restrictor 53) and flows into the outlet side flow path 27. The pressure oil that has flowed into the outlet-side flow path 27 is switched via the pair of actuator conduits 19A and 19B by switching the arm control valve 18 from the neutral position (A) to the switching position (B) or (C). The arm cylinder 9 is supplied and discharged.

  The flow rate of the pressure oil supplied to the arm cylinder 9 is determined by the opening area of the main valve 43 of the flow control valve 33 and the opening area of the spool 29 (switching lands 29A and 29B) of the arm control valve 18. Further, when the flow of the pressure oil from the inlet-side flow path 25 to the outlet-side flow path 27 of the housing 23 is interrupted, the main valve 43 of the flow control valve 33 has the valve portion 44D as the main valve seat 46 of the housing 23. The two flow paths 25 and 27 are blocked by being seated on.

  Here, when the flow rate from the inlet side channel 25 to the outlet side channel 27 is variably controlled, the pilot chamber 57 is pressurized by supplying the pilot pressure to the pilot chamber 57 of the pilot valve 55, and the pilot valve 55 is displaced toward the right in FIG. Thereby, the opening amount of the pilot throttle 56 of the pilot valve 55 is variably controlled. For example, when the pressure of the inlet side channel 25 is higher than that of the outlet side channel 27, a flow is generated from the inlet side channel 25 to the outlet side channel 27. At this time, a flow is generated in the inlet side flow path 25 → the check valve 62 → the feedback throttle 54 → the back pressure chamber 47, and two flows are generated from the back pressure chamber 47 to the outlet side flow path 27. One is the back pressure chamber 47 → the pilot throttle upstream pipe 51 → the pilot throttle 56 → the pilot throttle downstream pipe 52 → the outlet side flow path 27. The other is the back pressure chamber 47 → the fixed throttle 64 → the outlet side flow path 27.

  When the displacement amount in the valve opening direction of the main valve 43 is larger than the opening amounts of the pilot throttle 56 and the fixed throttle 64 that are the opening amounts between the back pressure chamber 47 and the outlet side flow passage 27, the feedback throttle 54 Therefore, the pressure in the back pressure chamber 47 approaches the pressure in the inlet-side channel 25. Accordingly, the main valve 43 receives a force in the valve closing direction due to the pressure in the back pressure chamber 47 and is displaced in the valve closing direction. As a result, the opening amount of the feedback throttle 54 decreases with the displacement of the main valve 43, so that the pressure in the back pressure chamber 47 is reduced and the valve closing direction due to the pressure of the back pressure chamber 47 acting on the main valve 43 is reduced. Power is reduced.

  As a result of this position feedback action, the main valve 43 has the “force in the valve opening direction due to the pressure of the inlet side channel 25 and the outlet side channel 27” and “the pressure in the back pressure chamber 47 and the valve closing direction by the valve spring 48. Stop at a position that balances the force. Thereby, the displacement amount of the main valve 43 is controlled so that the opening amount of the feedback throttle 54 corresponds to the opening amounts of the pilot throttle 56 and the fixed throttle 64 that are variably controlled. Along with this, by controlling the opening amount of the main valve throttle 53, the flow rate from the inlet side flow path 25 to the outlet side flow path 27 can be variably controlled.

  On the other hand, when the flow rate from the inlet side flow path 25 to the outlet side flow path 27 is controlled to the minimum, the pilot chamber 57 is pressurized to the maximum pressure, the pilot valve 55 is displaced to the maximum displacement, and the pilot throttle 56 is opened. The amount is controlled to 0 (zero). For example, when the pressure of the inlet side channel 25 is higher than that of the outlet side channel 27, a flow is generated from the inlet side channel 25 to the outlet side channel 27. At this time, a flow is generated in the inlet side flow path 25 → the check valve 62 → the feedback throttle 54 → the back pressure chamber 47, and there is only one flow from the back pressure chamber 47 to the outlet side flow path 27. That is, the back pressure chamber 47 → the fixed restrictor 64 → the outlet side flow path 27.

  By the position feedback action described above, the displacement amount of the main valve is controlled to the minimum so that the opening amount of the feedback restrictor 54 corresponds to the opening amount of the fixed restrictor 64. Along with this, the opening amount of the main valve throttle 53 is controlled to the minimum, whereby the flow rate from the inlet side flow path 25 to the outlet side flow path 27 can be controlled to the minimum.

  Further, regarding the load check function, when the pressure of the inlet-side channel 25 is lower than that of the outlet-side channel 27, a reverse flow tends to occur from the outlet-side channel 27 to the inlet-side channel 25. At this time, a flow occurs in the outlet side flow path 27 → the fixed throttle 64 → the back pressure chamber 47 → the feedback throttle 54 → the check valve 62 → the inlet side flow path 25, but this flow is blocked by the check valve 62. As a result, the pressures in the back pressure chamber 47 and the outlet-side flow path 27 become equal, and a force in the valve closing direction due to the pressure in the back pressure chamber 47 is generated in the main valve 43, and the main valve 43 is displaced in the valve closing direction. . Accordingly, the valve portion 44D of the main valve 43 is seated on the main valve seat 46, and the flow of the outlet side flow path 27 → the main valve throttle 53 → the inlet side flow path 25 is blocked. As a result, backflow from the outlet side channel 27 to the inlet side channel 25 is prevented, and a load check function can be achieved.

  As described above, according to the embodiment, the opening amount between the back pressure chamber 47 and the outlet-side flow path 27 is changed to the variable throttle (the pilot throttle 56 of the pilot valve 55) and the fixed throttle (the fixed throttle 64 of the main valve 43). ). For this reason, when the flow rate from the inlet-side channel 25 to the outlet-side channel 27 is controlled to the minimum, the minimum opening amount between the back pressure chamber 47 and the outlet-side channel 27 is configured only by the fixed throttle 64. Is done. As a result, even if relative variations in the axial direction occur between the pilot restrictor 56 and the pilot housing 36 due to manufacturing variations of parts, it is possible to suppress the variation in the minimum opening amount, and the inlet-side flow path 25 to the outlet-side flow path. The flow rate to 27 can be controlled to the minimum with high accuracy.

  FIG. 4 shows the relationship between the “displacement amount of the pilot valve 55”, the “opening amount of the pilot throttle 56”, the “displacement amount of the main valve 43”, and the “opening amount of the fixed throttle 64” by the flow rate control valve 33 of the embodiment. It is a characteristic diagram which shows an example. The solid line in FIG. 4 indicates the characteristic of the manufacturing variation “none”, and the broken line in FIG. 4 indicates the characteristic of the manufacturing variation “present”. As is apparent from FIG. 4, the flow control valve 33 of the embodiment maximizes the displacement of the pilot valve 55 by increasing the pressure in the pilot chamber 57 of the pilot valve 55 (that is, increasing the opening amount of the pilot throttle 56). When set to zero), the main valve displacement can be regulated as desired regardless of manufacturing variations. Thereby, it can suppress that the flow volume from the inlet side flow path 25 to the outlet side flow path 27 varies.

  In addition to this, in the embodiment, the displacement amount of the main valve 43 is fixed (constant) out of the flow rate from the back pressure chamber 47 to the outlet-side flow passage 27 necessary for controlling the displacement amount of the main valve 43. The flow rate for controlling the flow rate passes through a fixed throttle 64 provided between the back pressure chamber 47 and the outlet side flow path 27. For this reason, the flow rate passing through the pilot throttle 56 may be only a flow rate for variably controlling the displacement amount of the main valve 43, and the fluid force acting on the pilot throttle 56 is equivalent to the flow rate shared by the fixed throttle 64. Can be reduced. As a result, the opening amount of the pilot throttle 56 can be variably controlled with high precision, and the flow rate from the inlet side flow path 25 to the outlet side flow path 27 can be variably controlled with high precision.

  Further, since only the variable throttle needs to be formed in the pilot throttle 56, the size of the pilot valve 55 can be reduced as compared with the configuration in which both the variable throttle and the fixed throttle are provided in the pilot valve. . As a result, the pilot valve 55, and hence the pilot housing 36, can be reduced in size, and the manufacturing cost can be reduced and the component mounting property can be improved. In addition, the flow path that passes through the fixed throttle 64 that is the flow path from the outlet side flow path 27 to the back pressure chamber 47 is the pilot flow path 50 (pilot throttle upstream pipe 51, pilot throttle downstream pipe) that passes through the pilot throttle 56. It can be configured shorter than the path 52). For this reason, the responsiveness of the check valve 62 can also be improved, and the backflow of a working fluid can be prevented.

  In addition, since the fixed throttle 64 is provided on the outer peripheral portion of the main valve 43, the fluctuation range of the fluid force acting on the main valve 43 can be reduced. That is, the upstream side of the outlet side flow path 27 becomes a high pressure part having a high pressure by the jet flow that passes through the main valve throttle 53 of the main valve 43 and jets into the outlet side flow path 27, and this high pressure part passes through the fixed throttle 64. By increasing the pressure of the back pressure chamber 47, the fluid force in the valve opening direction acting on the main valve 43 can be reduced. Thereby, the fluctuation range of the fluid force applied to the main valve 43 between the minimum displacement position and the fully open position of the main valve 43 can be reduced.

  Further, according to the embodiment, the fixed throttle 64 is constituted by the main valve side communication groove 64 </ b> A provided on the outer peripheral surface of the main valve 43 and the wall surface of the main valve chamber 42. For this reason, by forming the main valve side communication groove 64 </ b> A on the outer peripheral surface of the main valve 43, a fixed throttle can be easily provided in the main valve chamber 42.

  In the above-described embodiment, the case where the main valve 43 is provided with the main valve side communication groove 64 </ b> A in order to configure the fixed throttle 64 has been described as an example. However, the present invention is not limited to this, and for example, a configuration in which the main valve chamber side communication groove 72A is provided on the wall surface of the main valve chamber 42 as in the first modification shown in FIG.

  That is, in the first modified example, the main valve 71 is not provided with the main valve side communication groove 64A as in the embodiment, like the main valve 102 of the first comparative example and the second comparative example. . However, in the first modified example, the wall surface (inner peripheral surface) of the main valve chamber 42 is provided with a plurality or a single main valve chamber side communication groove 72A. The main valve chamber side communication groove 72 </ b> A is provided in the axial direction of the valve body sliding hole 34 of the housing 23. The fixed throttle 72 is composed of a main valve chamber side communication groove 72 </ b> A and an outer peripheral surface of the main valve 71. According to such a second modification, the fixed throttle 72 can be easily provided in the main valve chamber 42 by forming the main valve chamber side communication groove 72 </ b> A on the wall surface of the main valve chamber 42.

  In the above-described embodiment, the pilot throttle 56 reduces the opening amount of the pilot flow path 50 in accordance with the displacement of the pilot valve 55, and the pilot flow path 50 before the displacement amount of the pilot valve 55 reaches the maximum value. The case where the opening amount is set to zero has been described as an example. However, the present invention is not limited to this. For example, as in the second modification shown in FIG. 6, the pilot throttle 82 of the pilot valve 81 is increased in accordance with the displacement of the pilot valve 81, And it is good also as a structure which makes the opening amount of the pilot flow path 50 zero before the displacement amount of the pilot valve 81 reaches the minimum value.

  That is, the pilot throttle 82 of the second modified example is provided as a variable throttle on the outer peripheral surface side of the pilot valve 81, like the pilot throttle 56 of the embodiment. In this case, in the second modified example, the pilot throttle 82 increases the opening amount of the pilot flow path 50 as the pilot valve 81 is displaced. That is, the pilot throttle 82 is piloted as the pilot valve 81 advances to one side in the axial direction (to the left in FIG. 6 and to the right in the right direction) as pressure oil (pilot pressure) is supplied to the pilot chamber 57. The opening amount of the flow path 50 is increased. In this case, for example, the pilot restriction 82 can be configured as a notch that decreases in depth as it travels to one side in the axial direction (away from the pilot chamber 57). FIG. 6 shows a state in which the pilot valve 81 has advanced to one side (right side) in the axial direction against the elastic force of the spring 60 based on the supply of pilot pressure.

  Further, the pilot throttle 82 has an opening amount of the pilot flow path 50 that is zero before the displacement amount of the pilot valve 81 reaches the minimum value. That is, the pilot valve 81 cuts off the connection between the pilot throttle upstream pipe 51 and the pilot throttle downstream pipe 52 before the displacement amount reaches the minimum value by proceeding from the right side to the left side in FIG. . The minimum value of the displacement amount of the pilot valve 81 corresponds to the position where the pilot pressure is not supplied to the pilot chamber 57, that is, the initial position returned by the spring 60. In the second modified example, as in the embodiment, the flow rate from the inlet side flow path 25 to the outlet side flow path 27 can be variably controlled with high accuracy, and the responsiveness of the check valve 62 is improved. can do.

  In the above-described embodiment, the case where one (integral or common) casing is configured by the housing 23 and the pilot housing 36 has been described as an example. However, the present invention is not limited to this. For example, as in the third modification shown in FIG. 7, the housing 23 and the pilot housing 36 are disposed separately, and the connection pipe line is provided between the housing 23 and the pilot housing 36. 91 and 91 may be provided. In this case, the main valve chamber 42 is provided in the housing 23. In other words, the main valve chamber 42 can adopt a configuration provided across the housing 23 and the pilot housing 36 as in the above-described embodiment, and can also be configured as provided in the housing 23 as in the third modification. be able to. In short, the main valve chamber is provided in at least the housing of the housing and the pilot housing.

  In the embodiment described above, the flow rate control valve 33 that adjusts the flow rate of the pressure oil supplied and discharged from the arm control valve 18 toward the arm cylinder 9 has been described as an example. However, the present invention is not limited to this. For example, the present invention may be applied to a flow rate control valve for adjusting the flow rate of pressure oil supplied to and discharged from the boom control valve 16 to the boom cylinder 8, and may be applied to a bucket cylinder or other hydraulic actuator. The present invention can also be applied to a flow rate control valve when pressure oil is supplied / discharged through a direction control valve.

  In the embodiment described above, the hydraulic excavator 1 has been described as an example of the construction machine. However, the present invention is not limited to this and can be widely applied to various construction machines such as a wheel loader, a hydraulic crane, and a bulldozer. Further, the flow control valve 33 may be configured to variably control the flow rate of the working fluid from the small flow rate to the large flow rate according to the displacement amount (lift amount) of the main valve 43, and various industrial equipment, It can be widely applied as a flow control valve for use in mechanical equipment. Furthermore, it is needless to say that the embodiments and the respective modifications are examples, and partial replacement or combination of the configurations shown in the different embodiments and modifications is possible.

1 Excavator (construction machine)
DESCRIPTION OF SYMBOLS 21 Control valve apparatus 23 Housing 25 Inlet side flow path 27 Outlet side flow path 33 Flow control valve 36 Pilot housing 42 Main valve chamber 43,71 Main valve 44D Valve part 46 Main valve seat 47 Back pressure chamber 49 Feedback flow path 50 Pilot flow Path 53 Main valve throttle 54 Feedback throttle 55, 81 Pilot valve 56, 82 Pilot throttle 62 Check valve 64, 72 Fixed throttle 64A Main valve side communication groove 72A Main valve chamber side communication groove

Claims (3)

A housing;
A pilot housing;
A main valve chamber provided in at least the housing of the housing and the pilot housing;
A main valve which is slidably provided in the main valve chamber and has a valve portion;
A main valve seat that is provided on one end side of the main valve chamber, and communicates and shuts off the working fluid by the valve portion of the main valve separating and seating; and
An inlet-side flow path that applies pressure in a direction away from the main valve seat to the main valve and introduces a working fluid from the outside of the main valve chamber into the main valve chamber;
When the main valve is separated from the main valve seat, the working fluid is led out from the main valve chamber to the outside of the main valve chamber, and the pressure in the direction away from the main valve seat is applied to the main valve. An outlet-side flow path for feeding,
A back pressure chamber that is provided on the other end side of the main valve chamber and applies pressure in a direction approaching the main valve seat to the main valve;
A feedback flow path provided in the main valve and communicating the inlet side flow path and the back pressure chamber;
A pilot flow path provided in the housing and the pilot housing and communicating the back pressure chamber and the outlet flow path;
A main valve throttle that is provided in the main valve and increases an opening amount between the inlet-side flow path and the outlet-side flow path in accordance with a displacement of the main valve in a direction away from the main valve seat;
It is provided between the feedback flow path and the back pressure chamber, and increases the amount of opening between the feedback flow path and the back pressure chamber as the main valve is displaced away from the main valve seat. Feedback throttling,
A pilot valve slidably provided in the pilot housing;
A pilot throttle provided in the pilot valve for reducing or increasing the opening amount of the pilot flow path in accordance with the displacement of the pilot valve;
A check valve provided in the feedback flow path, allowing a flow of the working fluid from the inlet-side flow path to the back pressure chamber, and blocking a flow opposite to this;
By controlling the amount of displacement of the main valve in accordance with the opening amount of the pilot throttle, the flow rate control function for variably controlling the flow rate from the inlet side channel to the outlet side channel is provided, and the outlet side A load check that prevents the flow of the working fluid from the outlet side channel to the inlet side channel by the main valve and the check valve when the pressure of the inlet side channel is lower than the pressure of the channel. In the flow control valve having a function,
The back pressure chamber is provided between the back pressure chamber and the outlet side flow path, communicates the back pressure chamber and the outlet side flow path without passing through the pilot flow path, and regardless of the amount of displacement of the main valve. A fixed throttle for fixing an opening amount between the back pressure chamber and the outlet-side flow path;
The flow rate control valve, wherein the pilot throttle is configured such that an opening amount of the pilot flow path becomes zero before a displacement amount of the pilot valve reaches a maximum value or a minimum value. A main valve side communication groove provided on the outer peripheral surface of the main valve;
The flow control valve according to claim 1, wherein the fixed throttle is configured by the main valve side communication groove and a wall surface of the main valve chamber. A main valve chamber side communication groove provided on the wall surface of the main valve chamber,
The flow control valve according to claim 1, wherein the fixed throttle is configured by the main valve chamber side communication groove and an outer peripheral surface of the main valve.

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