CN111692146A

CN111692146A - Control valve and hydraulic system for construction machinery

Info

Publication number: CN111692146A
Application number: CN202010081419.XA
Authority: CN
Inventors: 田岛丰三
Original assignee: Nabtesco Corp
Current assignee: Nabtesco Corp
Priority date: 2019-03-12
Filing date: 2020-02-06
Publication date: 2020-09-22
Also published as: JP2020148233A; JP7423189B2; KR20200109242A

Abstract

The invention provides a control valve and a hydraulic system for construction machinery. The control valve of the present invention comprises: a central passage portion which communicates the pump and the tank; a valve body provided in the middle of the center passage portion and capable of adjusting a flow rate of the fluid flowing through the center passage portion; and a bypass passage portion connected to the pump side and the tank side of the center passage portion with the valve body interposed therebetween.

Description

Control valve and hydraulic system for construction machinery

Technical Field

The present invention relates to a control valve and a hydraulic system for construction machinery.

Background

For example, a construction machine such as a hydraulic excavator includes a construction machine hydraulic system for driving a bucket, a boom, and the like. The hydraulic system for construction machinery includes a plurality of control valves. This control valve is provided with: a valve body; a central passage disposed within the valve body; a valve bore communicating with the central passage; a cylinder passage communicating with the valve hole; and a spool disposed to be movable within the valve hole. One end of the center passage is connected to a pump passage extending from the pump, and the other end is connected to a tank passage extending to the tank. The cylinder passage is connected to an actuator that drives the bucket and the boom. The spool includes a plurality of lands that slide on the inner peripheral surface of the cylinder hole.

The land has a function of switching the flow of the pressure oil pressurized and delivered from the pump by opening and closing the center passage and the cylinder passage. That is, there are cases where: when the spool is set to the neutral position, the center passage is opened, and the pressure oil pressurized and delivered from the pump flows directly to the tank. In addition, there are cases where: the pressure oil pressurized and delivered from the pump is supplied to the actuator according to the position of the shoulder in accordance with the movement of the valve column. The flow rate of the pressure oil supplied to the actuator is controlled by the position of the spool.

Here, since the pressure oil pressurized and delivered from the pump is supplied to the actuator via the control valve, a pressure loss occurs when the pressure oil passes through the control valve. This pressure loss affects the driving efficiency of the actuator. Therefore, the following techniques are proposed: the pressure loss of the pressure oil pressurized and delivered from the pump is reduced, and the actuator is driven as efficiently as possible. For example, a technique of providing a bypass passage between a pump passage and a cylinder passage has been proposed.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2017-67282

Disclosure of Invention

Problems to be solved by the invention

However, when a plurality of actuators are driven by a hydraulic system for a construction machine, a neutral open-type hydraulic circuit may be used. The hydraulic circuit has a plurality of control valves connected to a central passage. When the spool of the control valve is set to the neutral state, the pressure oil flows to the downstream side of the center passage, and the pressure oil is supplied to the control valve on the downstream side.

Here, the pressure oil flowing through the center passage causes a pressure loss when passing through the control valve.

Therefore, there is a possibility that the driving efficiency of the actuator connected to the control valve located on the downstream side of the center passage is reduced.

The invention provides a control valve and a hydraulic system for construction machinery, which can reduce the pressure loss of fluid flowing from a pump to a tank.

Means for solving the problems

A control valve according to an aspect of the present invention includes: a central passage portion which communicates the pump and the tank; a valve body provided in the middle of the center passage portion and capable of adjusting a flow rate of the fluid flowing through the center passage portion; and a bypass passage portion connected to the pump side and the tank side of the center passage portion with the valve body interposed therebetween.

With this configuration, the passage portion for the fluid flowing from the pump to the tank can be increased in addition to the center passage portion. Therefore, the pressure loss of the fluid flowing from the pump to the tank can be reduced.

In the above configuration, the bypass passage portion may have two different passage portions between the pump side and the tank side with the valve body interposed therebetween.

With this configuration, the fluid passing through the bypass passage further passes through the two passage portions, and therefore, the pressure loss of the fluid flowing from the pump to the tank can be reliably reduced.

As the above configuration, a valve body provided with a valve hole may be provided. The spool may be a spool provided to be movable in the valve hole. The center passage portion may include: a pump-side central passage portion provided on the pump side of the valve body with respect to the valve hole, and having a 1 st communication port communicating with the valve hole; and a tank-side central passage portion provided on the tank side of the valve body with respect to the valve hole, and having a 2 nd communication port communicating with the valve hole. The bypass passage portion may include: a pump-side bypass passage portion that branches from a midway point of the pump-side center passage portion and that has a 3 rd communication port that communicates with the valve hole; and a tank-side bypass passage portion that branches from a midway point of the tank-side center passage portion and that has a 4 th communication port that communicates with the valve hole. The 1 st communication port, the 2 nd communication port, the 3 rd communication port, and the 4 th communication port may be arranged in a staggered manner along the moving direction of the valve column in the order of the 1 st communication port, the 2 nd communication port, the 3 rd communication port, and the 4 th communication port. The spool may have: a land provided at a position corresponding to the 2 nd communication port and the 3 rd communication port in a neutral state; and flow path grooves provided at both ends of the land in the moving direction of the valve column.

The two flow channel grooves may be the two different passage portions.

With this configuration, the bypass passage portion can be provided in the valve body with a simple structure. In addition, two different passage portions may be provided in the bypass passage portion. Therefore, the control valve can be reduced in size at low cost, and the pressure loss of the fluid flowing from the pump to the tank can be reduced.

In the above configuration, the bypass passage may include another bypass passage that communicates at least one of the pump-side center passage and the tank-side center passage with the valve hole.

With this configuration, the bypass passage portion is further enlarged. Therefore, the pressure loss of the fluid flowing from the pump to the tank can be further reduced.

In the above configuration, the other bypass passage portion may include another pump-side bypass passage portion that branches from a midway point of the pump-side center passage portion and that has a 5 th communication port that communicates with the valve hole. The spool may have: another shoulder provided in the 4 th communication port in a neutral state; and another flow path groove provided at one end of the other land in a moving direction of the valve column.

With this configuration, the bypass passage portion can be further increased in the valve body with a simple structure. Therefore, the pressure loss of the fluid flowing from the pump to the tank can be further reduced while the control valve is reduced in size at low cost.

In the above configuration, a flow passage cross-sectional area of the bypass passage portion may be smaller than a flow passage cross-sectional area of the center passage portion.

With this configuration, the occupied space for providing the bypass passage can be reduced as much as possible.

Therefore, the control valve can be miniaturized.

In the above configuration, another valve body capable of adjusting the flow rate of the fluid flowing through the bypass passage portion may be provided in the middle of the bypass passage portion.

With this configuration, the flow rate of the fluid flowing through the bypass passage portion can be controlled. Therefore, the pressure loss of the fluid flowing from the pump to the tank can be reduced, and the control of the control valve can be performed with high accuracy.

A control valve according to another aspect of the present invention includes: a central passage portion which communicates the pump and the tank; a valve body provided in the middle of the central passage portion and having a valve hole communicating with the central passage portion; a spool provided so as to be movable in the valve hole and capable of adjusting a flow rate of the fluid flowing through the central passage portion; and a bypass passage portion connected to the pump side and the tank side of the center passage portion via the spool. The center passage portion has: a pump-side central passage portion provided on the pump side of the valve body with respect to the valve hole, and having a 1 st communication port communicating with the valve hole; and a tank-side central passage portion provided on the tank side of the valve body with respect to the valve hole, and having a 2 nd communication port communicating with the valve hole. The bypass passage portion includes: a pump-side bypass passage portion that branches from a midway point of the pump-side center passage portion and that has a 3 rd communication port that communicates with the valve hole; and a tank-side bypass passage portion that branches from a midway point of the tank-side center passage portion and that has a 4 th communication port that communicates with the valve hole. The 1 st communication port, the 2 nd communication port, the 3 rd communication port, and the 4 th communication port are arranged in a staggered manner along the moving direction of the valve column in the order of the 1 st communication port, the 2 nd communication port, the 3 rd communication port, and the 4 th communication port. The spool has: a land provided at a position corresponding to the 2 nd communication port and the 3 rd communication port in a neutral state; and flow path grooves provided at both ends of the land in the moving direction of the valve column.

With this configuration, the bypass passage portion can be provided in the valve body as a passage portion for fluid flowing from the pump to the tank with a simple structure in addition to the center passage portion.

Therefore, the control valve can be reduced in size at low cost, and the pressure loss of the fluid flowing from the pump to the tank can be reduced.

A control valve according to another aspect of the present invention includes: a central passage portion which communicates the pump and the tank; a valve body provided in the middle of the central passage portion and having a valve hole communicating with the central passage portion; a spool provided so as to be movable in the valve hole and capable of adjusting a flow rate of the fluid flowing through the central passage portion; and a bypass passage portion connected to the pump side and the tank side of the center passage portion via the spool. The center passage portion has: a pump-side central passage portion provided on the pump side of the valve body with respect to the valve hole, and having a 1 st communication port communicating with the valve hole; and a tank-side central passage portion provided on the tank side of the valve body with respect to the valve hole, and having a 2 nd communication port communicating with the valve hole. The bypass passage portion includes: a pump-side bypass passage portion that branches from a midway point of the pump-side center passage portion and that has a 3 rd communication port that communicates with the valve hole; a tank-side bypass passage portion that branches from a midway point of the tank-side center passage portion and that has a 4 th communication port that communicates with the valve hole; and another pump-side bypass passage portion that branches from a midway point of the pump-side center passage portion and that has a 5 th communication port that communicates with the valve hole. The 1 st, 2 nd, 3 rd, 4 th, and 5 th communication ports are arranged in the order of the 1 st, 2 nd, 3 rd, 4 th, and 5 th communication ports shifted in the moving direction of the valve column. The spool has: a land provided at a position corresponding to the 2 nd communication port and the 3 rd communication port in a neutral state; another shoulder provided in the 4 th communication port in a neutral state; flow path grooves provided at both ends of the shoulder in a moving direction of the valve column; and another flow path groove provided at one end of the other land in a moving direction of the valve column.

The bypass passage portion can be further increased in addition to the bypass passage portion with a simple structure in the valve body. Therefore, the pressure loss of the fluid flowing from the pump to the tank can be reliably reduced while the control valve is reduced in size at low cost.

A control valve according to another aspect of the present invention includes: a central passage portion which communicates the pump and the tank; a valve body provided in the middle of the center passage portion and capable of adjusting a flow rate of the fluid flowing through the center passage portion; a bypass passage portion connected to the pump side and the tank side of the center passage portion with the valve body interposed therebetween; and another valve body provided in the middle of the bypass passage portion and capable of adjusting the flow rate of the fluid flowing through the bypass passage portion.

In addition, the flow rate of the fluid flowing through the bypass passage portion can be controlled. Therefore, the pressure loss of the fluid flowing from the pump to the tank can be reduced, and the control of the control valve can be performed with high accuracy.

A hydraulic system for construction machinery according to another aspect of the present invention includes: the above-mentioned control valve; the pump is connected with the control valve; and an actuator that is driven based on pressure oil supplied from the pump via the control valve.

With this configuration, the pressure loss of the fluid flowing from the pump to the tank can be reduced, and the driving efficiency of the actuator can be improved.

In the above configuration, a plurality of the control valves may be provided to be connected to the center passage portion. At least the control valve located most upstream of the pump among the plurality of control valves may have the bypass passage portion.

With this configuration, the pressure loss of the fluid supplied to each control valve can be efficiently reduced.

ADVANTAGEOUS EFFECTS OF INVENTION

The control valve and the hydraulic system for construction machinery described above can reduce the pressure loss of the fluid flowing from the pump to the tank.

Drawings

Fig. 1 is a schematic configuration diagram of a hydraulic system for construction machinery according to an embodiment of the present invention.

Fig. 2 is a sectional view schematically showing a hydraulic control valve according to embodiment 1 of the present invention.

Fig. 3 is an enlarged view of a portion a of fig. 2.

Fig. 4 is a sectional view schematically showing a hydraulic control valve according to embodiment 2 of the present invention.

Fig. 5 is a sectional view schematically showing a hydraulic control valve according to embodiment 3 of the present invention.

Description of the reference numerals

1. A hydraulic system for construction machinery; 2. a hydraulic actuator (actuator); 3. 1 st hydraulic pump (pump); 4. 204, 304, hydraulic control valves (control valves); 5. tank 1 (pot); 6. a central passage; 9. 209, 309, valve body; 10. 210, 310, a spool (spool); 12. a bypass passage; 17. a valve bore; 18. a pump-side central passage; 19. a tank-side central passage; 21. the 1 st communication port; 22. a 2 nd communication port; 23. 223, a pump-side bypass passage; 223A, the 1 st pump side bypass passage; 223B, the 2 nd pump-side bypass passage (other bypass passage); 24. 324, a tank-side bypass passage; 25. a 3 rd communication port; 26. a 4 th communication port; 31. 1 st intermediate shoulder; 32. 2 nd intermediate shoulder; 37. a 1 st flow path groove; 38. 2 nd flow channel groove (flow channel groove, passage); 39. the 3 rd flow channel groove (flow channel groove, passage); 51. the 5 th communication port; 52. 3 rd intermediate shoulder (other shoulder); 53. the 4 th flow path groove (other flow path grooves); 60. an auxiliary control valve; 62. a spool (other spool); t1, T2, T3, T4, pathways.

Detailed Description

Next, embodiments of the present invention will be described with reference to the drawings.

(embodiment 1)

Fig. 1 is a schematic configuration diagram of a hydraulic system 1 for a construction machine.

As shown in fig. 1, a hydraulic system 1 for a construction machine is mounted on a construction machine such as a hydraulic excavator. The hydraulic system 1 for construction machinery has the following main structures: a plurality of hydraulic actuators (corresponding to the actuators of the claims) 2; a 1 st hydraulic pump (corresponding to a pump of claim) 3 that supplies desired pressure oil to each hydraulic actuator 2; and a plurality of hydraulic control valves (corresponding to the claimed control valves) 4 provided between the hydraulic actuator 2 and the 1 st hydraulic pump 3.

The hydraulic actuators 2 include a hydraulic cylinder 2a and a hydraulic motor 2 b. The hydraulic cylinder 2a is used for, for example, arm driving, bucket driving, and boom driving. The hydraulic motor 2b is used for, for example, cab pivoting and traveling. The hydraulic actuator 2 is not limited to these.

As the 1 st hydraulic pump 3, for example, a variable displacement hydraulic pump of a control system of a positive control is used.

The hydraulic control valve 4 is used to adjust the flow rate of the pressure oil to each hydraulic actuator 2. The hydraulic control valves 4 are connected to each other via a center passage (series passage) 6 that communicates between the 1 st hydraulic pump 3 and the 1 st tank (corresponding to a tank of the claims) 5, and a parallel passage 7 that branches from the center passage 6. Check valves 8 are provided in the parallel passages 7 so as to correspond to the respective hydraulic control valves 4. The check valve 8 prevents the reverse flow of the pressure oil supplied to each hydraulic control valve 4.

The hydraulic control valve 4 will be described in detail below. Since the plurality of hydraulic control valves 4 have the same configuration, only 1 hydraulic control valve 4 will be described in the following description, and the description of the other hydraulic control valves 4 will be omitted.

Fig. 2 is a cross-sectional view schematically showing the hydraulic control valve 4.

As shown in fig. 2, the hydraulic control valve 4 of the present embodiment includes: a valve body 9 having a plurality of oil passages; a spool (corresponding to a valve body of the claims) 10 disposed in the valve body 9; and a spool operation mechanism unit 11 that moves the spool 10.

As a structure for connecting the plurality of hydraulic control valves 4 to the center passage 6, a structure in which the plurality of spools 10 are connected to the 1 valve element 9 may be employed, or a structure in which the plurality of valve elements 9 having the 1 spool 10 are connected to each other may be employed. The valve body 9 including 1 spool 10 will be described below. However, even in the structure in which the plurality of spools 10 and the 1 valve element 9 are coupled, the following structure can be adopted.

The valve body 9 is provided with: a central passage 6; a bypass passage 12 branched from the center passage 6; cylinder port 1, 13 and

cylinder port

2, 14; a 1 st pressure oil discharge passage 15 and a 2 nd pressure oil discharge passage 16; and a valve hole 17 communicating with the center passage 6, the bypass passage 12, the 1 st cylinder port 13, the 2 nd cylinder port 14, the 1 st pressure oil discharge passage 15, and the 2 nd pressure oil discharge passage 16. In fig. 2, the center axis of the valve hole 17 is indicated by a one-dot chain line as O1.

The center passage 6 includes: a pump-side center passage 18 provided in the valve body 9 at a position closer to the 1 st hydraulic pump 3 than the valve hole 17; and a tank-side center passage 19 provided in the valve body 9 at a position closer to the 1 st tank 5 side than the valve hole 17. The flow passage cross-sectional areas of the

central passages

18, 19 are substantially the same.

The pump-side center passage 18 includes a 1 st communication port 21 that communicates with the valve hole 17. The tank-side center passage 19 includes a 2 nd communication port 22 communicating with the valve hole 17.

The bypass passage 12 includes: a pump-side bypass passage 23 branched from the pump-side center passage 18; and a tank-side bypass passage 24 branched from the tank-side center passage 19. The

bypass passages

23, 24 have a smaller flow passage cross-sectional area than the flow passage cross-sectional area of the

center passages

18, 19.

The pump-side bypass passage 23 includes a 3 rd communication port 25 that communicates with the valve hole 17. The tank-side bypass passage 24 includes a 4 th communication port 26 communicating with the valve hole 17. The

communication ports

21, 22, 25, and 26 are arranged so as to be shifted in the 1 st direction (left direction in fig. 2) D1 along the central axis O1 of the valve hole 17 in the order of the

communication ports

21, 22, 25, and 26.

The 1 st cylinder port 13 and the 2 nd cylinder port 14 are disposed on both sides of the center passage 6 and the bypass passage 12 in the direction of the center axis O1. The hydraulic actuator 2 is connected to the 1 st cylinder port 13 and the 2 nd cylinder port 14.

The 1 st pressure oil discharge passage 15 and the 2 nd pressure oil discharge passage 16 are disposed on both sides of the 1 st cylinder port 13 and the 2 nd cylinder port 14 in the direction of the center axis O1. The 1 st pressure oil discharge passage 15 and the 2 nd pressure oil discharge passage 16 are used to discharge pressure oil circulating in the valve body 9 and the hydraulic actuator 2 to the 1 st tank 5.

The area between the 1 st cylinder port 13 and the 2 nd cylinder port 14 at the valve hole 17 becomes an intermediate passage 27 through which pressure oil passes. Further, a 1 st supply port 28 for supplying pressure oil from the 1 st hydraulic pump 3 is provided between the 1 st cylinder port 13 and the intermediate passage 27. A 2 nd supply port 29 for supplying pressure oil from the 1 st hydraulic pump is provided between the 2 nd cylinder port 14 and the intermediate passage 27. The 1 st supply port 28 and the 2 nd supply port 29 communicate with the center passage 6 via a bridge-shaped supply passage, not shown.

The spool 10 disposed in the valve body 9 is housed in the valve hole 17.

The spool 10 is formed in a cylindrical shape so as to correspond to the cross-sectional shape of the valve hole 17.

The central axis O2 of the spool 10 coincides with the central axis O1 of the valve hole 17. The spool 10 is movable in the 1 st direction D1 and the 2 nd direction D2 (right direction in fig. 2) on the opposite side of the 1 st direction D1 along the center axis O1 within the valve hole 17. In the following description, the radial direction of the spool 10 will be simply referred to as the radial direction.

The spool 10 is provided with a plurality of lands 31 to 36 (a 1 st intermediate land 31, a 2 nd intermediate land 32, a 1 st land 33, a 2 nd land 34, a 3 rd land 35, and a 4 th land 36), and the like. The lands 31 to 36 change the flow rate and direction of the pressure oil flowing through the pump-side center passage 18, the tank-side center passage 19, the pump-side bypass passage 23, the tank-side bypass passage 24, the intermediate passage 27, the 1 st cylinder port 13, the 2 nd cylinder port 14, the 1 st pressure oil discharge passage 15, and the 2 nd pressure oil discharge passage 16. The outer diameters of the shoulders 31 to 36 are slightly smaller than the inner diameter of the valve hole 17. The lands 31 to 36 slide in the valve hole 17 when the spool 10 moves in the 1 st direction D1 and the 2 nd direction D2.

The 1 st intermediate land 31 and the 2 nd intermediate land 32 are provided at the center in the intermediate passage 27 in a no-load state (hereinafter, referred to as a "neutral state of the spool 10") in which the hydraulic actuator 2 is not driven. More specifically, in the neutral state of the spool 10, the 1 st intermediate land 31 is provided at a position radially opposed to the 2 nd communication port 22. In the neutral state of the spool 10, the 2 nd intermediate land 32 is provided at a position radially opposed to the 3 rd communication port 25.

On both sides of each of the

intermediate lands

31, 32 in the direction of the center axis O2, 3

flow grooves

37, 38, 39 (the 1 st flow groove 37, the 2 nd flow groove 38, the 3 rd flow groove 39) are provided over the entire circumference of the spool 10.

Here, the hydraulic control valve 4 adopts a so-called neutral open system: in the neutral state of the spool 10, the intermediate passage 27 is opened while the pump-side center passage 18 and the tank-side center passage 19 are communicated, and the pump-side bypass passage 23 and the tank-side bypass passage 24 are communicated (details will be described later).

The 1 st land 33 is provided on the 2 nd direction D2 side of the

intermediate lands

31 and 32 and at a position corresponding to the 1 st supply port 28. In the neutral state of the spool 10, the 1 st land 33 closes between the 1 st supply port 28 and the 1 st cylinder port 13.

The 2 nd land 34 is provided on the 1 st direction D1 side of the

intermediate lands

31 and 32 and corresponds to the 2 nd supply port 29. In the neutral state of the spool 10, the 2 nd land 34 seals between the 2 nd supply port 29 and the 2 nd cylinder port 14.

The 3 rd land 35 is provided on the 2 nd direction D2 side of the 1 st land 33 and at a position corresponding to the 1 st pressure oil discharge passage 15. In the neutral state of the spool 10, the 3 rd land 35 closes the 1 st pressure oil discharge passage 15 and the 1 st cylinder port 13.

The 4 th land 36 is provided on the 1 st direction D1 side of the 2 nd land 34 and at a position corresponding to the 2 nd pressure oil discharge passage 16. In the neutral state of the spool 10, the 4 th land 36 closes the gap between the 2 nd pressure oil discharge passage 16 and the 2 nd cylinder port 14.

A plurality of notch portions, not shown, are formed on the outer peripheral surfaces of the 1 st land 33, the 2 nd land 34, the 3 rd land 35, and the 4 th land 36. The notch portion serves as a passage for pressure oil.

The spool 10 thus configured moves along the center axes O1, O2 by the spool operating mechanism 11.

The spool operation mechanism portion 11 is provided on the 1 st direction D1 side of the spool 10. The spool operation mechanism 11 includes: an operating mechanism main body 41 including a pilot spool and a pressure chamber (both not shown); an adjustment unit 42 connected to the operating mechanism unit body 41; and a 2 nd hydraulic pump 43 coupled to the operating mechanism unit main body 41 via the adjustment unit 42.

The adjustment unit 42 adjusts the internal pressure of the pressure chamber of the operating mechanism unit body 41. The adjustment unit 42 includes an operation lever 44. The supply of the pressurized oil pressurized and fed from the 2 nd hydraulic pump 43 to the work mechanism main body 41 is controlled based on the operation of the operation lever 44. The spool 10 moves along the center axes O1, O2 by the pressure oil supplied to the operating mechanism main body 41. The pressure oil supplied to the operating mechanism main body 41 is then returned to the 2 nd tank 45.

Next, the flow of the pressure oil in the hydraulic control valve 4 will be described.

First, the neutral state of the spool 10 will be described with reference to fig. 2 and 3.

Fig. 3 is an enlarged view of a portion a of fig. 2.

As shown in fig. 2 and 3, in the neutral state of the spool 10, the intermediate passage 27 is opened to communicate the pump-side center passage 18 with the tank-side center passage 19 and to communicate the pump-side bypass passage 23 with the tank-side bypass passage 24. At this time, the pressure oil flowing through the pump-side center passage 18 passes through the pump-side center passage 18 and flows into the 1 st passage groove 37 from the gap formed between the 1 st communication port 21 and the 1 st land 33 (see arrow Y1). The pressure oil that has flowed into the 1 st flow path groove 37 flows into the tank-side center passage 19 from the gap formed between the 2 nd communication port 22 and the 1 st intermediate land 31 (see arrow Y2).

Then, the pressure oil flowing through the pump-side center passage 18 flows into the pump-side bypass passage 23 (see arrow Y3). The pressure oil that has flowed into the pump-side bypass passage 23 flows into the 2 nd flow path groove 38 and the 3 rd flow path groove 39 from two gaps formed between the 3 rd communication port 25 and the opposite ends of the 2 nd intermediate land 32 in the direction of the center axis O1 (see arrows Y4 and Y5). The pressure oil that has flowed into the 2 nd flow path groove 38 flows into the tank side center passage 19 from the gap formed between the 2 nd communication port 22 and the 1 st intermediate land 31 (see arrow Y6). The pressure oil that has flowed into the 3 rd flow path groove 39 flows into the tank-side bypass passage 24 from the gap formed between the 4 th communication port 26 and the 2 nd land 34 (see arrow Y7). The pressure oil flowing to the tank-side center passage 19 and the pressure oil flowing to the tank-side bypass passage 24 are then merged and returned to the 1 st tank 5.

Further, the above-described gaps are formed over the entire circumference of the valve hole 17 and the spool 10. Therefore, the pressure loss of the pressure oil when the pressure oil flows from these clearances into the valve hole 17, the tank-side center passage 19, and the tank-side bypass passage 24 is small.

The return flow to the 1 st tank 5 means a return flow to the 1 st tank 5 via the center passage 6. That is, in the hydraulic system 1 for construction machinery (see fig. 1) having a plurality of hydraulic control valves 4, the pressure oil flows to the pump-side center passage 18 of the hydraulic control valve 4 located on the downstream side.

Next, a case where the spool 10 is moved from the neutral state will be described.

First, the following will be explained: the spool 10 is moved in the 1 st direction D1 in the valve hole 17 by the operation of the operation lever 44.

When the spool 10 is moved in the 1 st direction D1, the 1 st supply port 28 and the 1 st cylinder port 13 communicate via the notched portion of the 1 st land 33. At this time, the 2 nd cylinder port 14 and the 2 nd pressure oil discharge passage 16 communicate with each other via the notch portion of the 4 th land 36. The intermediate passage 27, the tank-side center passage 19, and the tank-side bypass passage 24 are closed by the

intermediate lands

31 and 32.

Then, the pressure oil that has flowed into the pump-side center passage 18 is supplied to the hydraulic actuator 2 via the 1 st supply port 28, the cutout portion of the 1 st land 33, and the 1 st cylinder port 13. Thereby, the hydraulic actuator 2 is driven. At this time, the hydraulic oil discharged from the hydraulic actuator 2 flows back to the 1 st tank 5 via the 2 nd cylinder port 14, the cutout portion of the 4 th land 36, and the 2 nd pressure oil discharge passage 16.

Next, the following will be explained: the spool 10 is moved in the 2 nd direction D2 in the valve hole 17 by the operation of the operating lever 44.

When the spool 10 is moved in the 2 nd direction D2, the 2 nd supply port 29 and the 2 nd cylinder port 14 communicate via the notched portion of the 2 nd land 34. At this time, the 1 st cylinder port 13 and the 1 st pressure oil discharge passage 15 communicate with each other through the notch portion of the 3 rd land 35. The intermediate passage 27, the tank-side center passage 19, and the tank-side bypass passage 24 are closed by the

intermediate lands

31 and 32.

Then, the pressure oil that has flowed into the pump-side bypass passage 23 is supplied to the hydraulic actuator 2 via the 2 nd supply port 29, the cutout portion of the 2 nd land 34, and the 2 nd cylinder port 14. Thereby, the hydraulic actuator 2 is driven. At this time, the hydraulic oil discharged from the hydraulic actuator 2 flows back to the 1 st tank 5 via the 1 st cylinder port 13, the cutout portion of the 3 rd land 35, and the 1 st pressure oil discharge passage 15.

In this manner, the hydraulic control valve 4 includes: a spool 10 provided midway in the center passage 6, that is, between the pump-side center passage 18 and the tank-side center passage 19; and a bypass passage 12 (a pump-side bypass passage 23, a tank-side bypass passage 24) connecting the 1 st hydraulic pump 3 side (the pump-side center passage 18) and the 1 st tank 5 side (the tank-side center passage 19) of the center passage 6 with the spool 10 interposed therebetween. Therefore, as the passage of the pressure oil flowing from the 1 st hydraulic pump 3 to the 1 st tank 5, in addition to the 1 passage T1 (the passage T1 of the pressure oil flowing from the arrow Y1 to the arrow Y2 in fig. 3) flowing through the center passage 6, the passage T2 and the passage T3 (the passage T2 of the pressure oil flowing from the arrow Y4 to the arrow Y6 in fig. 3 and the passage T3 of the pressure oil flowing from the arrow Y5 to the arrow Y7 in fig. 3) flowing through the bypass passage 12 can be increased by an amount corresponding to the portion. Therefore, the pressure loss of the pressure oil flowing from the 1 st hydraulic pump 3 to the 1 st tank 5 can be reduced.

When the bypass passage 12 is provided, the valve body 9 is provided with a pump-side bypass passage 23 and a tank-side bypass passage 24. In addition to the 3 rd and 4

th communication ports

25, 26 of the

bypass passages

23, 24 communicating with the valve hole 17, the 1 st and 2

nd communication ports

21, 22 of the

center passages

18, 19 communicating with the valve hole 17 are arranged along the center axes O1, O2 in the order of the 1 st, 2 nd, 3 rd and 4

th communication ports

21, 22. In the neutral state of the spool 10, the 1 st intermediate land 31 is provided at a position corresponding to the 2 nd communication port 22 (a position facing in the radial direction), and the 2 nd intermediate land 32 is provided at a position corresponding to the 3 rd communication port 25 (a position facing in the radial direction). The intermediate lands 31 and 32 are provided with

passage grooves

37, 38, and 39 at both ends in the center axis O1 and O2 directions. With such a configuration, the bypass passage 12 can be provided in the valve body 9 with a simple structure, and two different pressure oil passages T2 and T3 (see fig. 3) can be provided. Therefore, the hydraulic control valve 4 can be reduced in size at low cost, and the pressure loss of the pressure oil flowing from the 1 st hydraulic pump 3 to the 1 st tank 5 can be reduced.

The

bypass passages

23, 24 have a smaller flow passage cross-sectional area than the

center passages

18, 19. Therefore, the space occupied for installing the

bypass passages

23 and 24 can be reduced as much as possible. Therefore, the hydraulic control valve 4 can be downsized.

In the above-described embodiment 1, the following case is explained: the center passage 6 and the bypass passage 12 provided in the valve body 9 are a pump-side center passage 18 and a pump-side bypass passage 23 provided on the 1 st hydraulic pump 3 side, and a tank-side center passage 19 and a tank-side bypass passage 24 provided on the 1 st tank 5 side. However, the present invention is not limited to this, and the pump-side center passage 18 and the pump-side bypass passage 23 may be provided on the 1 st tank 5 side of the valve body 9, and the tank-side center passage 19 and the tank-side bypass passage 24 may be provided on the 1 st hydraulic pump 3 side of the valve body 9.

(embodiment 2)

Next, embodiment 2 of the present invention will be described with reference to fig. 4. Note that the same reference numerals are used to describe the same manner as in embodiment 1 (the same applies to the following embodiments).

Fig. 4 is a sectional view schematically showing a hydraulic control valve 204 according to embodiment 2. Fig. 4 corresponds to the aforementioned fig. 3.

As shown in fig. 4, embodiment 1 is different from embodiment 2 in the following points: while the number of pump-side bypass passages 23 is 1 in embodiment 1, in embodiment 2, the pump-side bypass passage 23 is further branched and two pump-

side bypass passages

223A and 223B (a 1 st pump-side bypass passage 223A and a 2 nd pump-side bypass passage 223B) are provided.

The 1 st pump-side bypass passage 223A corresponds to the pump-side bypass passage 23 in embodiment 1. That is, the 1 st pump-side bypass passage 223A includes the 3 rd communication port 25 that communicates with the valve hole 17.

The 2 nd pump-side bypass passage (corresponding to another bypass passage, another pump-side bypass passage in the claims) 223B includes the 5 th communication port 51 communicating with the valve hole 17. The 5 th communication port 51 is disposed offset from the 3 rd communication port 25 in the 1 st direction D1.

The spool 210 is provided with a 3 rd intermediate land (corresponding to another land in the claims) 52 in addition to the 1 st intermediate land 31 and the 2 nd intermediate land 32 provided at the center in the intermediate passage 27 in the neutral state of the spool 210. The 3 rd intermediate land 52 is provided at a position radially opposed to the 4 th communication port 26 in the neutral state of the spool 210. On the 1 st direction D1 side of the 3 rd intermediate land 52, a 4 th flow path groove (corresponding to another flow path groove in claims) 53 is provided over the entire circumference of the spool 210. The 2 nd cylinder port 14, the 2 nd pressure oil discharge passage 16, the 3 rd land 35, and the like are offset in the 1 st direction D1 from the 1 st embodiment by the amount corresponding to the provision of the 2 nd pump-side bypass passage 223B, the 3 rd intermediate land 52, and the 4 th flow path groove 53.

Next, the flow of the pressurized oil passing through the pump-

side bypass passages

223A and 223B in the neutral state of the spool 210 will be described.

The flow of the pressure oil flowing into the 1 st pump-side bypass passage 223A is the same as the flow of the pressure oil flowing into the pump-side bypass passage 23 in embodiment 1 described above. That is, the pressure oil flows into the 2 nd flow path groove 38 and the 3 rd flow path groove 39 from two gaps formed between the 3 rd communication port 25 and the 2 nd intermediate land 32 at both ends in the center axis O1 direction (see arrows Y4 and Y5). The pressure oil that has flowed into the 2 nd flow path groove 38 flows into the tank side center passage 19 from the gap formed between the 2 nd communication port 22 and the 1 st intermediate land 31 (see arrow Y6). The pressure oil that has flowed into the 3 rd flow path groove 39 flows into the tank-side bypass passage 24 from the gap formed between the 4 th communication port 26 and the 3 rd intermediate land 52 (see arrow Y7).

On the other hand, the pressure oil that has flowed into the 2 nd pump-side bypass passage 223B flows into the 4 th flow path groove 53 from the gap formed between the 5 th communication port 51 and the 3 rd intermediate land 52 (see arrow Y8). The pressure oil that has flowed into the 4 th flow path groove 53 flows into the tank-side bypass passage 24 from the gap formed between the 4 th communication port 26 and the 3 rd intermediate land 52 (see arrow Y9). The pressure oil flowing through the tank-side center passage 19 and the pressure oil flowing through the tank-side bypass passage 24 are then merged and returned to the 1 st tank 5 (not shown in fig. 4).

Therefore, in embodiment 2, in addition to the same effects as those of embodiment 1, since two pump-

side bypass passages

223A and 223B are provided, the portion of the passage T4 for pressure oil (the passage T4 for pressure oil flowing from the arrow Y8 to the arrow Y9 in fig. 4) can be increased. Therefore, the pressure loss of the pressure oil flowing from the 1 st hydraulic pump 3 to the 1 st tank 5 can be further reduced.

When the bypass passage is added, the valve body 209 is provided with a 2 nd pump side bypass passage 223B in addition to the 1 st pump side bypass passage 223A. Further, a 3 rd intermediate land 52 and a 4 th flow channel 53 are additionally provided in the spool 210. In this way, a bypass passage can be added to the valve body 209 with a simple structure.

In embodiment 2 described above, the pump-side bypass passage 23 of embodiment 1 is provided as the two pump-

side bypass passages

223A and 223B. However, the present invention is not limited to this, and the tank-side bypass passage 24 according to embodiment 1 may be branched into two bypass passages. Further, the two

passages

23, 24 of the pump-side bypass passage 23 and the tank-side bypass passage 24 of embodiment 1 may be branched. The number of branches is not limited to two, and the

passages

23 and 24 of embodiment 1 may be branched into 3 or more. The number of intermediate lands of the spool 210 may be changed according to the number of branches.

(embodiment 3)

Next, embodiment 3 of the present invention will be described with reference to fig. 5.

Fig. 5 is a sectional view schematically showing a hydraulic control valve 304 according to embodiment 3. Fig. 5 corresponds to the aforementioned fig. 3.

As shown in fig. 5, in embodiment 3, an auxiliary control valve 60 independent of the hydraulic control valve 304 is provided in the middle of the bypass passage 12. This point is different from embodiment 1 described above.

More specifically, the bypass passage 12 includes a pump-side bypass passage 323 branched from the pump-side center passage 18 and a tank-side bypass passage 324 branched from the tank-side center passage 19. The

bypass passages

323 and 324 are not communicated with the valve hole 17 of the valve body 9, but connected to the auxiliary control valve 60. Thus, spool 310 of hydraulic control valve 304 has only 1 intermediate land 69.

The auxiliary control valve 60 includes a valve body 61 and a spool (corresponding to another valve body in the claims) 62 disposed in the valve body 61. The valve body 61 of the auxiliary control valve 60 may be integrated with the valve body 309 of the hydraulic control valve 304. That is, a part of the valve body 309 of the hydraulic control valve 304 may be the valve body 61 of the auxiliary control valve 60.

The valve body 61 is provided with a pump-side bypass passage 323 and a tank-side bypass passage 324, and a valve hole 63 communicating with these

bypass passages

323 and 324.

The pump-side bypass passage 323 includes the 1 st auxiliary communication port 64 that communicates with the valve hole 63. The tank-side bypass passage 324 includes the 2 nd auxiliary communication port 65 that communicates with the valve hole 63. The

auxiliary communication ports

64 and 65 are arranged offset from each other along the central axis O3 of the valve hole 63.

The spool 62 is housed in the valve hole 17 so as to be movable along the center axis O3. The spool 62 moves based on an operation of a spool operation mechanism portion, not shown.

The spool 62 includes two

lands

66 and 67 and a flow channel 68 provided between these

lands

66 and 67. In the neutral state of the spool 62, the pump-side bypass passage 323 and the tank-side bypass passage 324 communicate with each other via the passage groove 68 and the valve hole 63. When the spool 62 moves from the neutral state, the 1 st and 2 nd

auxiliary communication ports

64, 65 are closed by the

lands

66, 67.

Therefore, according to embodiment 3, the same effects as those of embodiment 1 are obtained. Further, according to embodiment 3, since the assist control valve 60 is provided in the middle of the bypass passage 12, the flow rate of the pressure oil flowing through the bypass passage 12 can be controlled. Therefore, the hydraulic control valve 304 can be controlled with high accuracy.

The present invention is not limited to the above-described embodiments, and various modifications may be made to the above-described embodiments without departing from the scope of the present invention.

For example, in the above-described embodiment, the case where the

hydraulic control valves

4, 204, and 304 are provided in the middle of the center passage 6 that communicates between the 1 st hydraulic pump 3 and the 1 st tank 5 has been described. The hydraulic control valve 4 is used to adjust the flow rate of the pressure oil to each hydraulic actuator 2. However, the structure of the bypass passage 12 described in each embodiment can be a control valve for adjusting the flow rate of various fluids other than oil.

In the above-described embodiment, the case where the plurality of

hydraulic control valves

4, 204, and 304 are connected to the center passage 6 is described. However, the present invention is not limited to this, and only 1

hydraulic control valve

4, 204, 304 may be provided in the center passage 6.

The case where the bypass passage 12 is provided to all of the plurality of

hydraulic control valves

4, 204, 304 is described. However, the bypass passage 12 may be provided in at least the

hydraulic control valves

4, 204, and 304 located most upstream and closest to the 1 st hydraulic pump 3. With this configuration, the pressure loss of the pressure oil supplied to each

hydraulic control valve

4, 204, 304 can be reduced efficiently.

Claims

1. A control valve, wherein,

the control valve includes:

a central passage portion which communicates the pump and the tank;

a valve body provided in the middle of the center passage portion and capable of adjusting a flow rate of the fluid flowing through the center passage portion; and

and a bypass passage portion connected to the pump side and the tank side of the center passage portion with the valve body interposed therebetween.

2. The control valve of claim 1,

the bypass passage portion has two different passage portions between the pump side and the tank side with the valve body interposed therebetween.

3. The control valve of claim 2,

the control valve is provided with a valve body provided with a valve hole,

the spool is a spool disposed to be movable within the valve bore,

the center passage portion has:

a pump-side central passage portion provided on the pump side of the valve body with respect to the valve hole, and having a 1 st communication port communicating with the valve hole; and

a tank-side central passage portion provided on the tank side of the valve body with respect to the valve hole and having a 2 nd communication port communicating with the valve hole,

the bypass passage portion includes:

a pump-side bypass passage portion that branches from a midway point of the pump-side center passage portion and that has a 3 rd communication port that communicates with the valve hole; and

a tank-side bypass passage portion that branches from a midway point of the tank-side center passage portion and that has a 4 th communication port that communicates with the valve hole,

the 1 st communication port, the 2 nd communication port, the 3 rd communication port, and the 4 th communication port are arranged in order of the 1 st communication port, the 2 nd communication port, the 3 rd communication port, and the 4 th communication port, with being shifted in a moving direction of the valve column,

the spool has:

a land provided at a position corresponding to the 2 nd communication port and the 3 rd communication port in a neutral state; and

flow path grooves provided at both ends of the shoulder in a moving direction of the valve column,

the two flow channel grooves are the two different passage portions.

4. The control valve of claim 3,

the bypass passage portion includes another bypass passage portion that communicates at least one of the pump-side center passage portion and the tank-side center passage portion with the valve hole.

5. The control valve of claim 4,

the other bypass passage portion has another pump-side bypass passage portion that branches from a midway point of the pump-side center passage portion and has a 5 th communication port that communicates with the valve hole,

the spool has:

another shoulder provided in the 4 th communication port in a neutral state; and

and another flow path groove provided at one end of the other land in a moving direction of the valve column.

6. The control valve according to any one of claims 1 to 5,

the bypass passage portion has a flow passage cross-sectional area smaller than that of the center passage portion.

7. The control valve according to any one of claims 1 to 5,

another valve body capable of adjusting the flow rate of the fluid flowing through the bypass passage portion is provided in the middle of the bypass passage portion.

8. The control valve of claim 6,

9. A control valve, wherein,

the control valve includes:

a central passage portion which communicates the pump and the tank;

a valve body provided in the middle of the central passage portion and having a valve hole communicating with the central passage portion;

a spool provided so as to be movable in the valve hole and capable of adjusting a flow rate of the fluid flowing through the central passage portion; and

a bypass passage portion connected to the pump side and the tank side of the center passage portion with the spool interposed therebetween,

the center passage portion has:

the bypass passage portion includes:

the spool has:

and a flow path groove provided at both ends of the shoulder in a moving direction of the valve column.

10. A control valve, wherein,

the control valve includes:

a central passage portion which communicates the pump and the tank;

the center passage portion has:

the bypass passage portion includes:

a pump-side bypass passage portion that branches from a midway point of the pump-side center passage portion and that has a 3 rd communication port that communicates with the valve hole;

a tank-side bypass passage portion that branches from a midway point of the tank-side center passage portion and that has a 4 th communication port that communicates with the valve hole; and

a pump-side bypass passage portion branched from a middle portion of the pump-side center passage portion and having a 5 th communication port communicating with the valve hole,

the 1 st communication port, the 2 nd communication port, the 3 rd communication port, the 4 th communication port, and the 5 th communication port are arranged in order of the 1 st communication port, the 2 nd communication port, the 3 rd communication port, the 4 th communication port, and the 5 th communication port shifted in a moving direction of the valve column,

the spool has:

a land provided at a position corresponding to the 2 nd communication port and the 3 rd communication port in a neutral state;

another shoulder provided in the 4 th communication port in a neutral state;

flow path grooves provided at both ends of the shoulder in a moving direction of the valve column; and

11. A control valve, wherein,

the control valve includes:

a central passage portion which communicates the pump and the tank;

a valve body provided in the middle of the center passage portion and capable of adjusting a flow rate of the fluid flowing through the center passage portion;

a bypass passage portion connected to the pump side and the tank side of the center passage portion with the valve body interposed therebetween; and

and another valve body provided in the middle of the bypass passage portion and capable of adjusting the flow rate of the fluid flowing through the bypass passage portion.

12. A hydraulic system for construction machinery, wherein,

the hydraulic system for construction machinery includes:

a control valve as claimed in any one of claims 1 to 11;

the pump is connected with the control valve; and

an actuator that is driven based on pressure oil supplied from the pump via the control valve.

13. The hydraulic system for construction machinery according to claim 12, wherein,

the hydraulic system for construction machinery includes a plurality of control valves connected to the center passage portion,

at least the control valve located most upstream closest to the pump among the plurality of control valves has the bypass passage portion.