JP2022166300A - flow control valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flow control valve capable of reducing influence of fluid power to improve a displacement characteristic of a main valve, to facilitate adjustment between the fluid power and an opening amount of a main valve throttle, and also capable of downsizing.

SOLUTION: A main valve throttle 53 of a main valve 43 is composed of a lateral hole 53A that communicates an inlet side flow path 25 and an outlet side flow path 27 via the inside of the main valve 43 (cylindrical protrusion part 44E), and a groove 53C that communicates the inlet side flow path 25 and the outlet side flow path 27 via the outer peripheral part of the main valve 43. The groove 53C is arranged so that working fluid ejected from the groove 53C changes the direction of the flow of the working fluid ejected from the lateral hole 53A. In this case, the direction of the flow of the working fluid F2 ejected from the lateral hole 53A is changed by the working fluid F1 ejected from the groove 53C so as to approach a direction parallel to a central axial line of the main valve 43.

SELECTED DRAWING: Figure 4

COPYRIGHT: (C)2023,JPO&INPIT

Description

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

Hydraulic circuits of construction machines such as hydraulic excavators, hydraulic cranes, and wheel loaders are provided with seat valve type flow control valves having a flow control function. This type of flow control valve variably controls the opening amount of a pilot throttle provided in a pilot valve so that the opening amount of a feedback throttle provided in the main valve corresponds to the opening amount of the pilot throttle. The displacement of the valve is controlled. As a result, the opening amount of the main valve throttle provided in the main valve is variably controlled, and the flow rate from the inlet side flow path to the outlet side flow path can be controlled to a desired value.

For example, when the pilot valve changes so that the amount of opening of the pilot throttle becomes smaller, the pressure in the back pressure chamber of the main valve approaches the pressure in the inlet-side channel. Therefore, the increase in back pressure applies force in the valve closing direction to the main valve, displacing the main valve in the valve closing direction. On the other hand, as the opening of the feedback throttle decreases as the main valve is displaced in the closing direction, the pressure in the back pressure chamber approaches the pressure in the outlet side passage, and the decrease in back pressure causes the main valve to open. A directional force is applied. As a result of this position feedback action, the main valve is positioned at a position where "the force in the valve opening direction due to the pressures in the inlet and outlet side channels" and "the force in the valve closing direction due to the back pressure and the spring" are balanced. Stop.

Here, Patent Document 1 describes a spool valve provided with a check valve (main valve). The check valve (main valve) disclosed in Patent Document 1 has a small-diameter portion and a tapered portion at the tip.

Japanese Patent Application Laid-Open No. 2006-017273 (Patent No. 4463028)

By the way, FIG. 8 shows a main valve 100 of a flow control valve according to a comparative example. A main valve throttle 101 of the main valve 100 is composed of a lateral hole 101A provided at the tip of the main valve 100 and a fixed throttle 101B. In this case, the fluid force generated by the lateral hole 101A may deteriorate the displacement characteristics of the main valve 100. That is, as shown in FIG. 8, when the displacement of the main valve 100 is maximum and the amount of opening of the lateral hole 101A is maximum, the jet flow passing through the main valve throttle 101 flows as indicated by the arrow A. The flow is perpendicular to the central axis of 100 . Therefore, fluid force acts on the main valve 100 in the valve opening direction. From this state, when the opening amount of the pilot throttle is reduced so that the main valve 100 is displaced in the valve-closing direction, the main valve 100 is reduced compared to the case where the fluid force in the valve-opening direction is not generated as described above. There is a possibility that the displacement characteristics at the beginning of closing of the

Further, when the main valve 100 begins to displace in the valve closing direction, the opening amount of the lateral hole 101A becomes smaller, and the jet flow passing through the main valve throttle 101 changes to flow in a direction parallel to the central axis of the main valve 100. That is, as the main valve 100 is displaced in the valve closing direction, the angle of the jet becomes shallower as indicated by arrow B in FIG. do. As a result, the fluid force acting on the main valve 100 in the valve-opening direction is reduced, and the main valve 100 tends to displace further in the valve-closing direction. Due to the repetition of this interaction, the main valve 100 may be rapidly displaced, deteriorating the displacement characteristics. That is, the main valve 100 of the comparative example may exhibit characteristics such that the displacement at the beginning of closing is slow and the displacement is abrupt during the displacement, as indicated by the dashed line (characteristic line 102) in FIG. 6, which will be described later. .

On the other hand, the throttle of the check valve (main valve) of Patent Document 1 is composed of a small-diameter portion and a tapered portion provided at the tip portion. According to this technique, it is considered that the opening amount of the main valve throttle and the fluid force can be adjusted by adjusting the relative relationship between the small diameter portion and the tapered portion. However, the phenomenon that the direction of the jet flow passing through the main valve throttle changes with the displacement of the main valve occurs in the same manner as in the comparative example described above. Therefore, it is considered difficult to sufficiently reduce the influence of the fluid force. Moreover, since the opening amount and the fluid force are closely related, it is considered difficult to determine a shape that satisfies both the opening amount and the fluid force.

On the other hand, as a general countermeasure for reducing the fluid force, it is considered to relatively reduce the ratio of the fluid force by increasing the pressure receiving diameter of the main valve to increase the pressure acting on the main valve. be done. However, in this case, there is a possibility that the size of the parts will increase and the manufacturing cost will increase. In addition, such techniques are difficult to apply to already manufactured conventional products.

An object of one embodiment of the present invention is to reduce the influence of fluid force to improve the displacement characteristics of the main valve, to easily adjust the opening amount of the main valve throttle and the fluid force, and to reduce the size of the valve. To provide a flow control valve that can be

One embodiment of the present invention comprises a housing, a pilot housing, a main valve chamber provided in the housing, a main valve slidably provided in the main valve chamber and having a valve portion, and the main valve chamber. A main valve seat provided on one end side of the main valve for communicating and blocking the working fluid by the valve portion of the main valve being seated and disengaged, and applying pressure to the main valve in a direction away from the main valve seat, an inlet-side passage for introducing working fluid from the outside of the main valve chamber into the interior of the main valve chamber; an outlet-side flow path for leading the working fluid to the outside and applying pressure to the main valve in a direction away from the main valve seat; a back pressure chamber that applies pressure in a direction toward the main valve seat; a feedback passage that is provided in the main valve and communicates the inlet side passage and the back pressure chamber; a pilot flow path that communicates between the back pressure chamber and the outlet side flow path; and the inlet side flow path that is provided in the main valve and moves along with displacement of the main valve in a direction away from the main valve seat. A main valve throttle that increases the amount of opening between the outlet-side flow path and a main valve throttle provided between the feedback flow path and the back pressure chamber that accompanies displacement of the main valve in a direction away from the main valve seat. a feedback throttle for increasing the amount of opening between the feedback flow path and the back pressure chamber; a pilot valve slidably provided in the pilot housing; A pilot throttle is provided to reduce or increase the opening amount of the pilot flow path according to the opening amount of the pilot throttle, and by controlling the amount of displacement of the main valve according to the opening amount of the pilot throttle, the inlet side flow path to the In a flow control valve having a flow control function for variably controlling a flow rate to an outlet-side channel, the main valve throttle communicates the inlet-side channel and the outlet-side channel via the interior of the main valve. and a groove that communicates the inlet-side flow path and the outlet-side flow path through the outer peripheral portion of the main valve. and the outer periphery of the main valve, the jet of the working fluid passing through the groove portion flows into the outlet-side flow path from the inlet-side flow path through the interior of the main valve and through the lateral hole. in the axial direction of the main valve with respect to the lateral hole so as to impinge on the jet of the working fluid passing through the lateral hole and flowing into the outlet-side flow path. It is formed as a communication passage that communicates with the

According to one embodiment of the present invention, the influence of fluid force can be reduced to improve the displacement characteristics of the main valve, the opening amount of the main valve throttle and the fluid force can be easily adjusted, and the size of the valve can be reduced. can be

That is, the main valve throttle is composed of a lateral hole and a groove. The jet passing through the groove collides with the jet passing through the lateral hole. At this time, the direction of flow of the working fluid ejected from the lateral hole is changed so as to approach a direction parallel to the central axis of the main valve by the working fluid ejected from the groove. Therefore, regardless of the displacement of the main valve and the opening amount of the main valve throttle, the direction of the jet flow passing through the main valve throttle is brought closer to the direction parallel to the central axis of the main valve when the side hole is open. be able to. As a result, when the displacement of the main valve is maximum and the amount of opening of the side hole is maximum, the fluid force acting on the main valve in the opening direction can be reduced, suppressing the delay in the displacement characteristics at the start of closing. can. In addition, when the main valve is displaced in the valve closing direction, it is possible to reduce the degree of decrease in fluid force in the valve opening direction, thereby suppressing rapid displacement of the main valve.

Furthermore, the opening amount of the main valve throttle is restricted by the "horizontal hole" and the "cylindrical surface-shaped opening formed from the housing". On the other hand, the fluid force can be adjusted by the "groove" and the "opening of the cross section perpendicular to the central axis of the main valve formed from the housing". Therefore, the opening amount of the main valve throttle and the fluid force can be adjusted independently, and the adjustment of the opening amount of the main valve throttle and the fluid force can be easily performed. In addition, since there is no need to increase the pressure receiving diameter of the main valve, the size can be reduced. Moreover, it can be implemented by simply applying additional processing to the conventional product.

1 is an overall configuration diagram showing a case where a flow control valve according to an embodiment is applied to a hydraulic circuit of a hydraulic excavator; FIG. FIG. 2 is a longitudinal sectional view showing a flow control valve and a direction control valve in FIG. 1; FIG. 3 is a vertical cross-sectional view showing an enlarged portion (III) in FIG. 2 ; FIG. 4 is a longitudinal sectional view of the same position as FIG. 3 showing the main valve in an opened state; It is a perspective view which shows a main valve. FIG. 5 is a characteristic diagram showing the relationship between pilot valve displacement amount, pilot valve opening amount, and main valve displacement amount; It is a perspective view which shows the main valve by a modification. FIG. 3 is a vertical cross-sectional view showing a main valve according to a comparative example;

A case where the flow control valve according to the embodiment is applied to a hydraulic circuit of a hydraulic excavator will be described below in detail with reference to FIGS. 1 to 7. FIG.

1 to 6 show embodiments. 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 rotatably mounted on the lower traveling body 2, and an upper revolving body. 3 includes a multi-joint structure work device 4 which is provided on the front side of the device 3 so as to be able to move up and down for excavation work and the like. In this case, the lower running body 2 and the upper revolving body 3 constitute the vehicle body of the hydraulic excavator 1 .

The working device 4, which is also called a working machine or front, includes, for example, a boom 5, an arm 6, a bucket 7 as a working tool, and a boom cylinder 8, an arm cylinder 9, and a bucket cylinder as hydraulic actuators (hydraulic actuators) for driving them. 10 (work tool cylinder). The work device 4 performs a vertical motion by extending or retracting hydraulic cylinders 8 , 9 , and 10 based on the supply of pressure oil from the hydraulic pump 11 . Note that FIG. 1 mainly shows hydraulic circuits relating to the boom cylinder 8 and the arm cylinder 9 in order to avoid complicating the drawing.

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

Here, branch lines 13A and 13B are provided in the middle of the pump line 13. As shown in FIG. One branch pipe line 13A is connected to a high-pressure side port (that is, an outlet side flow path 27 described later shown in FIG. 2) of the arm directional control valve 18 via a flow control valve 33 described later. The other branch pipeline 13B is connected to a high-pressure side port of a boom directional 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 directional control valve (both not shown), and the like.

A boom directional control valve 16 (hereinafter referred to as a boom control valve 16), which is a directional control valve for the boom cylinder 8, has left and right hydraulic pilot portions 16A and 16B, and is normally in a neutral position. ). In the boom control valve 16, pilot pressure is supplied from a boom lever operation device (not shown), which is a hydraulic pilot type operation valve, to the left and right hydraulic pilot portions 16A and 16B. It is switched from the neutral position (a) to the switching positions (b) and (c).

A pair of actuator pipes 17A and 17B are provided between the boom cylinder 8 and the boom control valve 16 . One actuator 17A 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 line 17B connects the rod side oil chamber (not shown) of the boom cylinder 8 to the other pressurized 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, and is normally in a neutral position. ). In the arm control valve 18, pilot pressure is supplied from an arm lever operation device (not shown), which is a hydraulic pilot type operation valve, to the left and right hydraulic pilot portions 18A and 18B. It is switched from the neutral position (a) to the switching positions (b) and (c).

A pair of actuator pipes 19A and 19B are provided between the arm cylinder 9 and the arm control valve 18 . One actuator pipe line 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 inflow/outflow passage 28B shown in FIG. 2). It is something to do. The other actuator pipe line 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 inflow/outflow passage 28A shown in FIG. 2). It is something to do.

When the arm control valve 18 is switched from the neutral position (a) to the switching position (b), pressure oil from the hydraulic pump 11 flows through the branch pipe 13A, a flow control valve 33 (to be described later), the arm control valve 18, and the actuator. It is supplied to the bottom side oil chamber of the arm cylinder 9 via the pipe line 19A, and the pressure oil in the rod side oil chamber is discharged to the tank 12 via the actuator pipe line 19B, the arm control valve 18, and the tank pipe line 15. . As a result, the arm cylinder 9 is extended by the pressurized oil supplied to the bottom side oil chamber, and rotates the arm 6 downward.

When the arm control valve 18 is switched from the neutral position (a) to the switching position (c), pressure oil from the hydraulic pump 11 flows through the branch pipe 13A, the flow control valve 33, the arm control valve 18, and the actuator pipe. 19B to the rod-side oil chamber of the arm cylinder 9, and the pressure oil in the bottom-side oil chamber is discharged to the tank 12 through the actuator pipe line 19A, the arm control valve 18, and the tank pipe line 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 rotated upward.

The relief valve 20 is a variable set pressure 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 the excess pressure at this time to the tank line 15 side. The relief valve 20 has 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 from the outside to the pilot oil chamber 20B. Thereby, the relief valve 20 has a configuration in which the relief set pressure can be adjusted in 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 control valve 33 which will be 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. and The housing 23 and the pilot housing 36 are separately formed as separate parts. By attaching the pilot housing 36 to the housing 23, the valve casing 22 that becomes one (integrated or common) casing is configured.

Next, the arm control valve 18 of the control valve device 21 will be described. 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 slide hole 24, an inlet-side channel 25, an outlet-side channel 27, a pair of inflow/outflow channels 28A and 28B, a spool 29, and left and right valves. It includes lids 30A and 30B, a stopper 31, and a spring 32. As shown in FIG. 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 slide hole 24, an inlet-side channel 25, an outlet-side channel 27, and a pair of inflow/outflow passages 28A and 28B.

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

The first annular oil grooves 24A and 24B communicate with each other through an outlet-side flow path 27 that is generally formed in an inverted U shape. The first annular oil grooves 24A, 24B communicate with and disconnect from the second annular oil grooves 24C, 24D when the spool 29 is displaced leftward and rightward from the neutral position shown in FIG. The second annular oil grooves 24C, 24D always communicate with the pair of actuator pipes 19A, 19B via left and right inflow/outflow passages 28A, 28B. The third annular oil grooves 24</b>E, 24</b>F are always in communication with the tank 12 via each tank pipe line 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 apart from the spool slide hole 24 in the radial direction. In this case, the inlet-side flow path 25 extends along a direction perpendicular to the spool slide hole 24 (front and back directions in FIG. 2). The inlet-side channel 25 is connected to the hydraulic pump 11 via the pump line 13 (more specifically, the branch 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 path 27 communicates with the first annular oil grooves 24A and 24B which are spaced apart from each other.

The communication hole 26 is arranged at a position facing the later-described valve body slide hole 34 across the outlet side flow path 27 . The communication hole 26 communicates the inlet-side channel 25 with the outlet-side channel 27 so as to intersect. The communication hole 26 constitutes a main valve chamber 42 together with a valve body slide hole 34 and a recessed portion 37 of the pilot housing 36, which will be described later. A tapered main valve seat 46 serving as an annular valve seat on which a main valve 43 (to be described later) is seated or disengaged is provided at the intersection of the outlet-side channel 27 and the communication hole 26 .

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

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

As shown in FIG. 2, the spool 29 selectively communicates the second annular oil grooves 24C, 24D with either the first annular oil grooves 24A, 24B or the third annular oil grooves 24E, 24F. , and switching lands 29A and 29B for blocking. A plurality of notches 29A1 and 29B1 for finely adjusting the flow rate of pressure oil are formed in the switching lands 29A and 29B, respectively, spaced apart in the circumferential direction.

Here, when the spool 29 slides leftward in FIG. 2, the switching land 29A of the spool 29 communicates the first annular oil groove 24A with the second annular oil groove 24C. Along with this, 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 As a result, the arm control valve 18 switches from the neutral position (a) shown in FIG. 1 to the right switching position (c).

On the other hand, when the spool 29 slides rightward in FIG. 2, the switching land 29B of the spool 29 communicates the first annular oil groove 24B with the second annular oil groove 24D. Along with this, the switching land 29A of the spool 29 blocks 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 lid bodies 30A and 30B constitute an arm control valve 18 together with the spool 29. As shown in FIG. The lids 30A and 30B are attached to the housing 23 on both sides of the spool slide hole 24 in the axial direction (left and right directions). The lids 30A and 30B close both ends of the spool slide hole 24. As shown in FIG. The right lid 30B is longer than the left lid 30A, and a centering spring 32 is provided in the right lid 30B. Hydraulic pilot portions 18A and 18B are provided inside the lids 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 leftward and rightward in FIG. 2 in the spool sliding hole 24 according to the pilot pressure at this time.

The stopper 31 is provided integrally with the spool 29 on the right side of the spool 29 . The stopper 31 is disposed displaceably within the lid 30B and has a shaft portion 31A extending axially within the lid 30B. The stopper 31 regulates the stroke end of the spool 29 when the spool 29 is displaced rightward in FIG.

A 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 31A of the stopper 31 and is arranged between the end surface of the spool 29 and the stopper 31 with an initial load applied in advance. The spring 32 holds the spool 29 at the neutral position when the pilot pressure from the hydraulic pilot portions 18A, 18B drops 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 state in which the main valve 43 is closed, and FIG. 4 shows the maximum flow rate state in which the main valve 43 is most open.

The flow control valve 33 is a poppet valve device that adjusts the flow rate of pressure oil supplied to the arm cylinder 9 . The flow 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 passage 25 , an outlet side passage 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 and a pilot throttle 56 .

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

The valve body sliding hole 34 is arranged 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 slide hole 34 extends between the pilot housing 36 and the outlet side flow path 27 in a direction perpendicular to the spool slide hole 24 (upward and downward directions 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 . A main valve 43 is inserted (fitted) into the main valve chamber 42 so as to be displaceable.

The branch passage 35 is an oil passage branched from the middle of the outlet-side flow passage 27 . The branch passage 35 always communicates with the second passage 40 on the pilot housing 36 side. The branch passage 35 forms a pilot passage 50 together with a second passage 40 and a 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 block the valve body slide hole 34 of the housing 23 from the outside. The pilot housing 36 has a recess 37 that houses a main valve 43 and a valve spring 48, a valve housing hole 38 that houses a pilot valve 55 and the like, and a space between the valve housing hole 38 and the recess 37. and a second passage 39 extending obliquely between the branch passage 35 of the housing 23 and the valve accommodating hole 38 and communicated with and blocked from the first passage 39 by the pilot valve 55 . and a pilot pressure supply/discharge port 41 are provided. The supply/discharge port 41 is connected to a pilot chamber 57 defined by the inner surface of the valve housing 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 composed of the valve body slide 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 serves as the valve body of the flow control valve 33 and has a valve portion 44D. In this case, the main valve 43 includes a stepped valve member 44 inserted into the valve body sliding hole 34, and a check valve 62 which is screwed to one axial side of the valve member 44 and serves as a check valve 62 described later. and a valve holding member 45 that is displaceably held between the member 44 and the valve holding member 45 . The valve holding member 45 includes a spring receiving portion 45A that supports the valve spring 48 in a contracted state between (the bottom portion of) the recess 37 of the pilot housing 36, and a valve member 44 (described below) formed in a tubular shape with a bottom. It includes a holding cylinder portion 45B that displaceably holds the check valve 62 inside while being screwed into the upper portion of the hole portion 44G. 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 slidably inserted into the valve body slide hole 34, a small-diameter cylindrical portion 44B provided on one side of the large-diameter portion 44A in the axial direction, and a large-diameter portion. A valve portion 44D, which is integrally formed on the other side in the axial direction of 44A via a reduced diameter portion 44C having a small diameter and whose outer peripheral side is seated and separated from the main valve seat 46 of the housing 23, and the other side (front end side) of the valve portion 44D. and a tubular projecting portion 44</b>E axially projecting toward the inlet-side flow path 25 . In this case, the valve portion 44D is also called a seat portion and provided in the main valve 43 (valve member 44). The valve portion 44</b>D blocks the flow of working fluid between the inlet-side channel 25 and the outlet-side channel 27 by contacting (seating on) the main valve seat 46 .

In addition, the valve member 44 extends from the inner peripheral side of the cylindrical protruding portion 44E to 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 portion 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 portion 44G, and a feedback throttle 54, which will be described later, are provided. The stepped hole portion 44G communicates with the inlet-side flow path 25 via the inner peripheral side of the cylindrical projecting portion 44E. The radial hole 44</b>H communicates with a back pressure chamber 47 to be described later via a feedback throttle 54 . Thus, the stepped hole portion 44G and the radial hole 44H form a feedback flow path 49. As shown in FIG. A main valve throttle 53, which will be described later, is provided on the tubular projecting portion 44E of the valve member 44. As shown in FIG.

The main valve seat 46 is provided on one end side of the main valve chamber 42 (on the inlet side flow path 25 side). That is, the main valve seat 46 is provided in the housing 23 at the intersection of the outlet-side channel 27 and the communication hole 26, and is configured as a tapered annular valve seat. The main valve seat 46 communicates and shuts off the working fluid when the valve portion 44D of the main valve 43 is seated and disengaged.

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

The outlet channel 27 is provided in the housing 23 and connected to the spool slide 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 flows from the inside of the main valve chamber 42 (communication hole 26 side) to the outside of the main valve chamber 42 (spool slide hole of the arm control valve 18 ). 24 side, more specifically, the arm cylinder 9 side). Along with this, the outlet-side channel 27 applies pressure to the main valve 43 in a direction away from the main valve seat 46 (valve opening direction). The outlet channel 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 (the side opposite to the inlet-side flow path 25). The back pressure chamber 47 applies pressure to the main valve 43 in a direction toward the main valve seat 46 (valve closing direction). 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 always communicates with the first passage 39 of the pilot housing 36 .

The valve spring 48 is positioned within the back pressure chamber 47 and disposed between (the valve holding member 45 of) the main valve 43 and (the bottom of) the recess 37 of the pilot housing 36 . The valve spring 48 is configured using a coil spring or the like, and always 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 the 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 is formed by the stepped hole portion 44G and the 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 . Thereby, the feedback channel 49 communicates the inlet side channel 25 and the back pressure chamber 47 .

Pilot flow path 50 is provided in housing 23 and pilot housing 36 . That is, the pilot flow path 50 is composed of the branch passage 35 of the housing 23 and the first passage 39 and the second passage 40 of the pilot housing 36 . Thereby, the pilot channel 50 communicates the back pressure chamber 47 and the outlet side channel 27 . In this case, the first passage 39 constitutes a pilot throttle upstream pipe line 51 which is a pipe line on the upstream side of the pilot throttle 56, and the second passage 40 and the branch passage 35 are on the downstream side of the pilot throttle 56. constitutes a pilot restrictor downstream pipeline 52 which is a pipeline.

The main valve throttle 53 is provided on the tip side (on the inlet side flow path 25 side) of the main valve 43 (more specifically, the valve member 44). As will be described later, the main valve throttle 53 is composed of a lateral hole 53A, a fixed throttle 53B, and a groove portion 53C. As the main valve 43 is displaced in the direction away from the main valve seat 46 (displaced upward in the upward and downward directions in FIGS. 2 to 4), the main valve throttle 53 is displaced between the inlet side flow path 25 and the outlet side flow path. 27 is increased.

A feedback throttle 54 is provided between the feedback flow path 49 and the back pressure chamber 47 . 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 as the main valve 43 moves away from the main valve seat 46 (valve opening direction).

As shown in FIG. 2 , the pilot valve 55 is slidably provided in 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 and pressurizing the working fluid into the pilot chamber 57 . As the pilot valve 55 is displaced, the working fluid inside the drain chamber 59, which will be described later, is discharged from the drain port 59A.

A pilot throttle 56 is provided in 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 amount of opening of the pilot flow passage 50 as the pilot valve 55 is displaced. That is, as the pilot throttle 56 is supplied with pressure oil (pilot pressure) to the pilot chamber 57, the pilot valve 55 moves to one side in the axial direction (to the right in the left and right directions in FIG. 2). The amount of opening of the flow path 50 is reduced. In this case, the pilot aperture 56 is configured as a notch with a constant depth. Note that the pilot throttle may be configured as a notch whose depth becomes deeper as it progresses toward one side in the axial direction (as it moves away from the pilot chamber 57), for example.

The lid 58 is positioned on one axial side of the valve housing hole 38 and 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 housing hole 38 . A spring 60 is provided between the lid body 58 and the pilot valve 55 in a compressed state. A spring 60 urges the pilot valve 55 in the valve opening direction via a washer 61 .

When the pilot valve 55 is placed at the communication position (a) shown in FIG. 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 under 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, which is a pilot pressure as an external command pressure supplied to the pilot chamber 57 via the supply/discharge port 41 from a remotely controlled valve (not shown) for external commands. When it rises above, it slides against the spring 60 and cuts off the first and second passages 39 and 40 . As a result, the pilot valve 55 is switched from the communicating 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 communicates with the second passage 40 (outlet-side passage 27) with a minimum opening amount. As a result, the main valve 43 is at the minimum opening position.

A check valve 62 is provided in the feedback flow path 49 . That is, the check valve 62 is housed 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 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 working fluid to flow from the inlet-side channel 25 to the back pressure chamber 47 and blocks (blocks) the opposite flow. That is, the check valve 62 opens against the spring 63 so as to be separated from the valve seat 44F when the pressure in the inlet-side flow path 25 acts from the side of the tubular projection 44E of the valve member 44 . As a result, the pressure oil in the inlet-side flow path 25 is supplied to the back pressure chamber 47 via the stepped hole portion 44</b>G and radial hole 44</b>H of the valve member 44 and the feedback throttle 54 . In this manner, the check valve 62 allows pressure oil to flow through the main valve 43 from the inlet-side flow path 25 toward the back pressure chamber 47 and prevents reverse flow. That is, the check valve 62 prevents the hydraulic fluid in the back pressure chamber 47 from flowing toward the stepped hole portion 44G and the inlet side passage 25 via 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 rate control valve 33 controls the amount of displacement (the amount of lift, that is, the opening area) of the main valve 43 in accordance with the amount of opening of the pilot throttle 56, so that the flow from the inlet side flow path 25 to the outlet side flow path 27 (the flow rate of pressure oil flowing through the arm control valve 18) is variably controlled. Along with this, the flow control valve 33 controls the flow of working fluid (oil liquid) from the outlet-side channel 27 to the inlet-side channel 25 when the pressure in the inlet-side channel 25 is lower than the pressure in the outlet-side channel 27 . The main valve 43 and the check valve 62 block the flow of the load check function.

Next, the main valve throttle 53 of the main valve 43 will be described. The main valve throttle 53 moves from the inlet side flow path 25 to the outlet side flow path 27 via the communication hole 26 as the main valve 43 is displaced in the axial direction (upward and downward displacement in FIGS. 2 to 4). The flow rate of the flowing pressure oil (the opening area of the communication hole 26 with respect to the outlet-side flow path 27) is adjusted. The main valve throttle 53 is composed of a plurality of (eg, eight) lateral holes 53A, a plurality of (eg, four) fixed throttles 53B, and a plurality of (eg, eight) grooves 53C.

The lateral hole 53A is provided in the cylindrical projecting portion 44E of the main valve 43. As shown in FIG. The lateral hole 53A extends in the radial direction of the main valve 43 (direction perpendicular to the central axis of the main valve 43). That is, the lateral hole 53A is formed in the tubular projecting portion 44E as a through hole penetrating between the outer peripheral side and the inner peripheral side of the tubular projecting portion 44E. The fixed throttle 53B is located closer to the valve portion 44D than the lateral hole 53A and is provided on the cylindrical projecting portion 44E of the main valve 43. As shown in FIG. The fixed throttle 53B extends in the radial direction of the main valve 43 (the direction orthogonal to the central axis of the main valve 43), and is formed in the tubular projecting portion 44E as a throttle hole having a smaller diameter than the lateral hole 53A. That is, the fixed diaphragm 53B also penetrates between the outer peripheral side and the inner peripheral side of the cylindrical projecting portion 44E, like the lateral hole 53A. The lateral hole 53A and the fixed throttle 53B communicate the inlet-side channel 25 and the outlet-side channel 27 via the inside of the main valve 43 (more specifically, the inside of the tubular projecting portion 44E).

The groove portion 53C is positioned closer to the opening side of the cylindrical projecting portion 44E than the lateral hole 53A and provided on the outer peripheral side of the cylindrical projecting portion 44E. The groove portion 53C communicates the inlet-side channel 25 and the outlet-side channel 27 via the outer peripheral portion of the main valve 43 (the outer peripheral side of the cylindrical projecting portion 44E). The groove portion 53C is formed as a communication passage that communicates with the lateral hole 53A in the axial direction of the main valve 43 between the housing 23 and the outer periphery of the main valve 43 . That is, the groove portion 53C extends in the axial direction of the main valve 43 (parallel to the central axis of the main valve 43) from the opening side of the cylindrical projecting portion 44E. The groove portion 53C extends from the opening side of the tubular projecting portion 44E to the lateral hole 53A. In this case, the groove portion 53C extends in a direction perpendicular to the central axis of the lateral hole 53A. That is, the groove portion 53C is arranged so that the working fluid ejected from the groove portion 53C changes the flow direction of the working fluid ejected from the lateral hole 53A. In this case, the direction of flow of the working fluid ejected from the lateral hole 53A is changed so as to approach a direction parallel to the central axis of the main valve 43 by the working fluid ejected from the groove 53C.

That is, as shown in FIG. 4, the working fluid F1 ejected from the groove portion 53C collides with the working fluid F2 ejected from the lateral hole 53A. As a result, the working fluid F2 ejected from the lateral hole 53A can be brought closer to the direction parallel to the central axis of the main valve 43 than the jet flow A in FIG. As a result, the fluid force acting on the main valve 43 in the valve opening direction can be reduced. In the embodiment, the same number of grooves 53C and lateral holes 53A are provided. In this case, the position of the groove portion 53C in the circumferential direction of the main valve 43 coincides with the lateral hole 53A. That is, the groove portion 53C and the lateral hole 53A are in phase with each other in the circumferential direction of the main valve 43 . In other words, a plurality of groove portions 53C are provided at equal intervals around the main valve 43 for each of the plurality of lateral holes 53A.

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

First, pressure oil discharged from the hydraulic pump 11 flows from the branch pipe 13A of the pump pipe 13 to the inlet-side passage 25 of the housing 23 and between the main valve 43 and the communication hole 26 of the flow control valve 33 (main valve It flows through the throttle 53) and into the outlet-side channel 27. By switching the arm control valve 18 from the neutral position (a) to the switching position (b) or (c), the pressure oil that has flowed into the outlet-side flow path 27 flows through the pair of actuator pipes 19A and 19B. is supplied to and discharged from the arm cylinder 9.

The flow rate of 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 blocking the flow of pressure oil from the inlet-side channel 25 of the housing 23 to the outlet-side channel 27 , the main valve 43 of the flow control valve 33 moves the valve portion 44</b>D to the main valve seat 46 of the housing 23 . , the flow paths 25 and 27 are cut off.

Here, when the flow rate from the inlet-side channel 25 to the outlet-side channel 27 is variably controlled, the pilot pressure is supplied to the pilot chamber 57 of the pilot valve 55 to pressurize the pilot chamber 57, and the pilot valve 55 is displaced toward the right in FIG. As a result, the opening amount of the pilot throttle 56 of the pilot valve 55 is variably controlled. Then, 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 passage 25→check valve 62→feedback throttle 54→back pressure chamber 47, and the back pressure chamber 47→pilot throttle upstream line 51→pilot throttle 56→pilot throttle downstream line 52→ A flow also occurs in the outlet-side channel 27 .

Here, when the amount of displacement of the main valve 43 in the valve opening direction is large with respect to the amount of opening of the pilot throttle 56, which is the amount of opening between the back pressure chamber 47 and the outlet side passage 27, the feedback throttle 54 Since the amount of opening is large, the pressure in the back pressure chamber 47 approaches the pressure in the inlet-side channel 25 . As a result, the main valve 43 receives 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 as the main valve 43 is displaced, so the pressure in the back pressure chamber 47 is reduced, and the pressure in the back pressure chamber 47 acting on the main valve 43 moves the valve in the closing direction. power decreases.

As a result of this position feedback action, the main valve 43 exerts force in the valve opening direction due to the pressures of the inlet side flow path 25 and the outlet side flow path 27 and pressure in the back pressure chamber 47 and the valve closing direction due to the valve spring 48. stop at a position where the force is balanced. As a result, the displacement amount of the main valve 43 is controlled so that the opening amount of the feedback throttle 54 corresponds to the opening amount of the pilot throttle 56 that is variably controlled. Accordingly, 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. At this time, the main valve 43 is displaced to the position shown in FIG. 4 so that the opening amount of the main valve throttle 53 is composed of the lateral hole 53A and the fixed throttle 53B.

On the other hand, when controlling the flow rate from the inlet side flow path 25 to the outlet side flow path 27 to a minimum, the pilot chamber 57 is pressurized to the maximum pressure, the pilot valve 55 is displaced to the maximum displacement amount, and the pilot throttle 56 is opened. The quantity is controlled to a minimum. Here, for example, when the pressure of the inlet-side channel 25 is higher than that of the outlet-side channel 27 , a flow occurs from the inlet-side channel 25 to the outlet-side channel 27 . At this time, a flow is generated in the inlet side passage 25→check valve 62→feedback throttle 54→back pressure chamber 47, and the back pressure chamber 47→pilot throttle upstream line 51→pilot throttle 56→pilot throttle downstream line 52→ A flow also occurs in the outlet-side channel 27 .

Due to the position feedback action described above, the amount of displacement of the main valve 43 is controlled to the minimum so that the amount of opening of the feedback throttle 54 corresponds to the amount of opening of the pilot throttle 56 . Along with this, the amount of opening of the main valve throttle 53 is controlled to a minimum, so that the flow rate from the inlet side flow path 25 to the outlet side flow path 27 can be controlled to a minimum. At this time, the main valve 43 is slightly displaced from the position shown in FIG.

Further, regarding the load check function, when the pressure in the inlet-side channel 25 is lower than that in the outlet-side channel 27 , there is a tendency for a reverse flow to occur from the outlet-side channel 27 to the inlet-side channel 25 . At this time, a flow is generated in the outlet side flow path 27→pilot throttle downstream line 52→pilot throttle 56→pilot throttle upstream line 51→back pressure chamber 47→feedback throttle 54→check valve 62→inlet side flow path 25. , this flow is blocked by check valve 62 . As a result, the pressure in the back pressure chamber 47 and the pressure in the outlet-side channel 27 become equal, so that the pressure in the back pressure chamber 47 generates a force in the valve closing direction in the main valve 43, displacing the main valve 43 in the valve closing direction. . As a result, the valve portion 44D of the main valve 43 is seated on the main valve seat 46, and the flow of the outlet side passage 27→main valve throttle 53→inlet side passage 25 is blocked. As a result, reverse flow from the outlet side channel 27 to the inlet side channel 25 is prevented, and the load check function can be achieved.

Next, the valve open state shown in FIG. 4, that is, the state in which the displacement of the main valve 43 is maximum and the amount of opening of the main valve throttle 53 is maximum will be described. In the valve open state shown in FIG. 4, there are two flow paths passing through the main valve throttle 53 . One is inlet-side channel 25 → inside of main valve 43 (cylindrical projecting portion 44E) → lateral hole 53A or fixed throttle 53B → outlet-side channel 27, and the other is inlet-side channel 25 → main valve 43 ( The groove portion 53C on the outer peripheral side of the cylindrical projecting portion 44E)→the outlet side flow path 27. The jet (working fluid F1) passing through the groove portion 53C collides with the jet (working fluid F2) passing through the lateral hole 53A. At this time, the jet (working fluid F2) passing through the lateral hole 53A (and the fixed throttle 53B) is directed in a direction parallel to the central axis of the main valve 43 by the jet (working fluid F1) passing through the groove 53C. be changed.

Therefore, the direction of the jet that passes through the main valve throttle 53 can be brought closer to the direction parallel to the central axis of the main valve 43 in the state where the lateral hole 53A is open. As a result, when the displacement of the main valve 43 is maximum and the amount of opening of the lateral hole 53A is maximum, the fluid force acting on the main valve 43 in the valve opening direction can be reduced. Here, a characteristic line 71 in FIG. 6 indicates the relationship between the "displacement amount of the pilot valve 55" and the "displacement amount of the main valve 43" according to the embodiment. A characteristic line 102 in FIG. 6 indicates the relationship between the "displacement amount of the pilot valve" and the "displacement amount of the main valve 100" according to the comparative example shown in FIG. As shown in FIG. 6, when the opening amount of the pilot throttle 56 is reduced so that the main valves 43, 100 are displaced in the valve-closing direction, the comparative example (characteristic line 102) tends to delay the closing start characteristics. In contrast, the embodiment (characteristic line 71) can improve this phenomenon.

Further, even when the main valve 43 begins to displace in the valve closing direction and the opening amount of the lateral hole 53A becomes small, the opening of the groove 53C does not change, so the direction of the jet passing through the groove 53C does not change. Therefore, the direction of the jet that passes through the lateral hole 53A (and the fixed throttle 53B) can be kept close to the direction parallel to the central axis of the main valve 43. FIG. As a result, the degree of decrease in fluid force in the valve opening direction can be reduced. That is, as shown in FIG. 6, when the opening amount of the pilot throttle 56 is reduced so that the main valves 43, 100 are displaced in the valve-closing direction, in the comparative example (characteristic line 102), the displacement is abrupt during the displacement. This phenomenon can be improved in the embodiment (characteristic line 71).

Further, the opening amount of the main valve throttle 53 is restricted by the "horizontal hole 53A" and the "cylindrical surface-shaped opening formed from the housing 23". On the other hand, the fluid force can be adjusted by the "groove 53C" and the "opening of the cross section in the direction perpendicular to the central axis of the main valve 43 formed by the housing 23". Therefore, the opening amount of the main valve throttle 53 and the fluid force can be adjusted independently, and the opening amount of the main valve throttle 53 and the fluid force can be easily adjusted. In addition, since there is no need to increase the pressure receiving diameter of the main valve 43, the size can be reduced. Moreover, it can be implemented by simply applying additional processing to the conventional product.

Further, according to the embodiment, the position of the groove portion 53C in the circumferential direction of the main valve 43 coincides with the lateral hole 53A. That is, a plurality of groove portions 53C are provided at equal intervals around the main valve 43 for each of the plurality of lateral holes 53A. Therefore, the jet flowing through the groove portion 53C can directly collide with the jet flowing through the lateral hole 53A.

In the above-described embodiment, the eight lateral holes 53A are provided, and the same number of grooves 53C as the lateral holes 53A are provided. However, the number of lateral holes 53A and grooves 53C is not limited to this, and may be more than eight or less than eight. Further, the numbers of the lateral holes 53A and the grooves 53C may be varied within the range where the required opening amount and fluid force characteristics can be obtained. The same applies to the fixed diaphragm 53B.

In the above-described embodiment, the case where a plurality of grooves 53C are provided corresponding to a plurality of lateral holes 53A has been described as an example. However, the present invention is not limited to this, and for example, as in a modification shown in FIG. 7, a configuration in which a small diameter portion 81 serving as one groove portion is provided for a plurality of lateral holes 53A may be employed. That is, in the modification shown in FIG. 7, the outer diameter dimension is smaller than that of the portion where the lateral hole 53A is provided on the distal end side of the main valve 43, more specifically, on the outer peripheral surface of the distal end side of the tubular projecting portion 44E. A small diameter portion 81 having a small diameter is provided.

Thus, in the modified example, the groove portion is configured by the small diameter portion 81 provided at the tip of the main valve 43 . In such a modification, the jet flow passing through the small-diameter portion 81 as the groove collides with the jet flow passing through the lateral hole 53A. can. Moreover, according to the modified example, the groove (small diameter portion 81 ) can be easily formed at the tip of the main valve 43 . That is, compared with the configuration in which a plurality of grooves are provided, the work of forming the grooves can be reduced.

In the embodiment described above, the case where the housing 23 and the pilot housing 36 form one (integral or common) casing has been described as an example. However, the configuration is not limited to this, and for example, the housing and the pilot housing may be arranged separately, and a connection pipe line may be provided between the housing and the pilot housing. In this case, the main valve chamber is provided in the housing. That is, the main valve chamber can be provided in the housing and the pilot housing as in the above-described embodiment, or can be provided in the housing. 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 case where the pilot throttle 56 of the pilot valve 55 is configured to reduce the opening amount of the pilot flow path 50 as the pilot valve 55 is displaced has been described as an example. However, without being limited to this, for example, the pilot throttle of the pilot valve may be configured to increase the amount of opening of the pilot passage along with the displacement of the pilot valve.

In the above-described embodiment, the flow control valve 33 that adjusts the flow rate of pressure oil supplied and discharged from the arm control valve 18 toward the arm cylinder 9 has been described as an example. However, it is not limited to this, for example, it may be applied to a flow 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 to a bucket cylinder or other hydraulic actuator. It can also be applied to a flow control valve for supplying and discharging pressurized oil through a directional control valve.

In the embodiment described above, the hydraulic excavator 1 has been described as an example of the construction machine. However, it is not limited to this, and can be widely applied to various construction machines such as wheel loaders, hydraulic cranes, and bulldozers. In addition, the flow control valve 33 may be configured to variably control the flow rate of the working fluid from a small flow rate to a large flow rate according to the displacement amount (lift amount) of the main valve 43. It can be widely applied as a flow control valve used in mechanical equipment. Furthermore, the embodiments and modifications are examples, and it goes without saying that partial replacements or combinations of the configurations shown in the embodiments and modifications are possible.

1 Hydraulic excavator (construction machinery)
21 control valve device 23 housing 25 inlet channel 27 outlet channel 33 flow control valve 36 pilot housing 42 main valve chamber 43 main valve 44D valve portion 46 main valve seat 47 back pressure chamber 49 feedback channel 50 pilot channel 53 Main valve throttle 53A Lateral hole 53C Groove 54 Feedback throttle 55 Pilot valve 56 Pilot throttle 81 Small diameter portion (groove)

Claims (6)

a housing;
a pilot housing;
a main valve chamber provided in the housing;
a main valve slidably provided in the main valve chamber and having a valve portion;
a main valve seat that is provided on one end side of the main valve chamber and that communicates and shuts off the working fluid by the valve portion of the main valve being seated and separated;
an inlet-side passage that applies pressure to the main valve in a direction away from the main valve seat and introduces working fluid from the outside of the main valve chamber into the interior of the main valve chamber;
When the main valve is separated from the main valve seat, the working fluid is introduced from the inside of 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 channel to provide;
a back pressure chamber provided on the other end side of the main valve chamber and applying pressure to the main valve in a direction approaching the main valve seat;
a feedback flow path provided in the main valve and communicating between the inlet-side flow path and the back pressure chamber;
a pilot flow path provided in the housing and the pilot housing and communicating between the back pressure chamber and the outlet-side flow path;
a main valve throttle that is provided in the main valve and increases an opening amount between the inlet-side channel and the outlet-side channel as the main valve is displaced in a direction away from the main valve seat;
provided between the feedback flow path and the back pressure chamber to increase an opening amount between the feedback flow path and the back pressure chamber as the main valve is displaced in a direction away from the main valve seat feedback aperture and
a pilot valve slidably provided in the pilot housing;
A pilot throttle is provided in the pilot valve and reduces or increases the opening amount of the pilot flow path as the pilot valve is displaced,
A flow control valve having a flow rate control function that variably controls the flow rate from the inlet side flow path to the outlet side flow path by controlling the amount of displacement of the main valve according to the opening amount of the pilot throttle,
The main valve throttle includes a lateral hole that communicates the inlet-side channel and the outlet-side channel through the inside of the main valve, and a lateral hole that communicates the inlet-side channel and the outlet-side channel through the outer peripheral portion of the main valve. and a groove that communicates with the flow path,
In the groove, a jet of working fluid flowing from the inlet-side flow path, passing through the groove between the housing and the outer periphery of the main valve, and flowing to the outlet-side flow path is jetted from the groove to the outlet-side flow path. A jet of working fluid flowing from a side passage through the interior of the main valve, through the lateral hole, and into the outlet-side passage collides with the jet of the working fluid passing through the lateral hole in the axial direction of the main valve with respect to the lateral hole. A flow control valve characterized in that it is formed as a communication passage that communicates with the The flow control valve according to claim 1,
The groove is configured so that when the main valve is displaced and the lateral hole is open, the opening of the groove does not change regardless of the displacement of the main valve. control valve. The flow control valve according to claim 1,
the lateral hole is provided extending in a direction perpendicular to the central axis of the main valve,
The flow control valve, wherein the groove is provided parallel to the central axis of the main valve. The flow control valve according to claim 1,
The flow control valve, wherein the groove is formed on the outer periphery of the main valve so as to extend from the tip of the main valve to the lateral hole. The flow control valve according to claim 1,
A flow control valve, wherein a plurality of said grooves are provided at equal intervals around said main valve with respect to each of said plurality of lateral holes. The flow control valve according to claim 1,
The flow control valve, wherein the groove portion is composed of a small diameter portion provided at the tip of the main valve.

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