WO2018147108A1

WO2018147108A1 - Directional control valve

Info

Publication number: WO2018147108A1
Application number: PCT/JP2018/002667
Authority: WO
Inventors: 岩崎　仁; 明紀阿部
Original assignee: ナブテスコ株式会社
Priority date: 2017-02-09
Filing date: 2018-01-29
Publication date: 2018-08-16
Also published as: CN110268168B; JP2018128103A; KR102500484B1; CN110268168A; KR20190115050A; JP6755814B2

Abstract

Provided is a simply structured directional control valve that change the supply flow of a hydraulic fluid. According to the present invention, a valve main body (31) has: a first branch passage (48) and a first parallel passage (46) that communicate with a first pump (51); a second branch passage (49) and a second parallel passage (47) that communicate with a second pump (52); and a bridge passage (43) that opens at a spool hole (33). The bridge passage (43) is divided into a confluence passage (45) and a connecting passage (44). When a spool (32) is in a first position, the confluence passage (45) communicates with: the first branch passage (48) and/or the first parallel passage (46); and the second branch passage (49) and/or the second parallel passage (47). When the spool (32) is in a second position, the connecting passage (44) communicates with the first branch passage (48) and/or the first parallel passage (46).

Description

Directional switching valve

The present invention relates to a direction switching valve that regulates the flow of hydraulic oil.

A hydraulic circuit system that drives various actuators with hydraulic oil (that is, pressure oil) supplied from two pumps is known. In such a hydraulic circuit system, the flow of hydraulic oil from the two pumps is restricted by a direction switching valve, and the operation of each actuator is controlled.

Patent Document 1 discloses a direction switching valve that can selectively form a plurality of types of passage patterns. In this direction switching valve, a plurality of types of passage patterns can be selectively formed by disposing a check valve, a stopper, or the like between each of the tandem passage and the parallel passage and the bridge passage.

JP 2016-138619 A

In order to drive a heavy operating device such as a boom of a hydraulic excavator, a hydraulic cylinder having a large area is used as an actuator, and it is necessary to supply a large flow rate of hydraulic oil to the hydraulic cylinder, particularly when driving up. For example, when the boom is raised, it is necessary to supply hydraulic oil with a relatively large flow rate to the hydraulic cylinder in order to move the boom against gravity while ensuring a sufficient speed. On the other hand, when lowering the boom, since the potential energy of the boom can be used, it is only necessary to supply hydraulic oil with a relatively small flow rate to the hydraulic cylinder.

As described above, the flow rate of the hydraulic oil required for driving the actuator is not necessarily constant, and varies depending on a specific operation state. Therefore, it is preferable to adjust the flow rate of the hydraulic oil supplied to the hydraulic cylinder by the above-described direction switching valve according to the specific operating state of the actuator. However, it is not easy to realize such a directional switching valve with a simple structure, and the mere addition of a flow path, a valve, a plug, and the like complicates the structure of the directional switching valve and causes an increase in cost.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a directional switching valve having a simple structure capable of changing the supply flow rate of hydraulic oil.

One aspect of the present invention is a valve main body having a spool hole formed therein, a spool disposed in the spool hole, and a bridge passage formed in a bridge shape and opened to the spool hole, wherein the junction passage and the communication passage are formed by a blocking portion. And a first passage, a second passage, a third passage, and a fourth passage formed in the valve body, and the first passage and the second passage are the first passage and the second passage. When communicating with one pump, the third flow path and the fourth flow path communicate with the second pump, and the spool is disposed at the first position, at least one of the first flow path and the second flow path When one side and at least one of the third flow path and the fourth flow path are communicated with the merging passage and the spool is disposed at the second position, the first flow path and the second flow path The present invention relates to a direction switching valve in which at least one of them communicates with a communication passage.

The valve body has an actuator passage that opens into the spool hole and communicates with the actuator, and is one of the first flow path and the second flow path and at least one of the third flow path and the fourth flow path. One communicates with the merging passage, and the communication passage communicates with the other of the first flow path and the second flow path but does not communicate with the merging passage. The spool is connected to the bridge passage according to the arrangement position in the spool hole. When the communication state and the shut-off state with the actuator passage are changed and the spool is arranged at the first position, the spool communicates with the communication passage while communicating the merging passage with the actuator passage through the spool hole. When the spool is disposed between the actuator passage and the spool is disposed at the second position, the spool passes through the spool hole while blocking between the merging passage and the actuator passage. The communication passage may be communicated with the actuator passage.

Another aspect of the present invention includes a valve body in which a spool hole is formed, and a spool disposed in the spool hole. The valve body includes a first unload passage communicated with the first pump, a second A second unload passage communicated with the pump, a first supply passage communicated with the first pump, a second supply passage communicated with the second pump, and an actuator opened to the spool hole and communicated with the actuator A passage, a bridge passage opening in the spool hole, a first parallel region capable of forming a first parallel passage for communicating the first supply passage and the bridge passage, and a second for communicating the second supply passage and the bridge passage. A second parallel region capable of forming a parallel passage, a first branch passage that connects any one of the first supply passage and the first unload passage to the bridge passage, a second supply passage, A second branch passage that communicates either one of the unload passages with the bridge passage, and the bridge passage includes the first parallel passage and the merge passage that communicates with the second parallel passage, and the first branch passage. And a communication passage that does not communicate with the merging passage, and the spool changes the communication state and the blocking state between the bridge passage and the actuator passage according to the arrangement position in the spool hole, and the spool When the spool is disposed at the first position, the spool communicates with the actuator passage through the spool hole while blocking between the communication passage and the actuator passage, and the spool is disposed at the second position. In this case, the spool blocks the connection between the joining passage and the actuator passage, and communicates the communication passage with the actuator passage through the spool hole. About the direction switching valve.

The blocking portion may block one end of the communication passage while closing one end of the junction passage.

The actuator passage has a first actuator passage that is disposed closer to the joining passage among the joining passage and the communication passage, and a second actuator passage that is disposed closer to the joining passage among the joining passage and the communication passage. When the spool is disposed in the first position, the spool blocks the connection passage and the first actuator passage while communicating the joining passage with the second actuator passage through the spool hole, When the spool is disposed at the second position, the spool may connect the communication passage to the first actuator passage through the spool hole while blocking between the joining passage and the second actuator passage. .

When the spool is disposed at the third position, the spool may block between the junction path and the actuator path while blocking between the communication path and the actuator path.

The direction switching valve includes a first check valve that prevents backflow of hydraulic oil from the merging passage to the second flow path, a second check valve that prevents backflow of hydraulic oil from the merging path to the third flow path, and the first from the communication passage. You may further provide at least any one of the 3rd check valve which prevents the backflow of the hydraulic fluid to a flow path, and the 4th check valve which prevents the backflow of the hydraulic oil from a merge channel to a 4th flow path.

The actuator may be a hydraulic cylinder.

The actuator may be an actuator for driving the boom.

According to the present invention, a directional switching valve capable of changing the supply flow rate of hydraulic oil can be realized with a simple structure.

FIG. 1 is an external view schematically showing a typical configuration example of a hydraulic excavator. FIG. 2 is a sectional view of the direction switching valve. FIG. 3 shows a hydraulic circuit diagram of the excavator, and particularly shows a case where the boom is raised by driving the hydraulic cylinder in the forward direction. FIG. 4 shows a hydraulic circuit diagram of the excavator, and particularly shows a case where the boom is lowered by driving the hydraulic cylinder in the reverse direction.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Below, the case where this invention is applied with respect to the direction switching valve used for the hydraulic circuit for driving a boom with respect to a hydraulic shovel is demonstrated. However, the object to which the present invention can be applied is not limited to the direction switching valve used in the hydraulic excavator. For example, the present invention can be applied to construction machines other than hydraulic excavators and hydraulic drive devices other than construction machines.

FIG. 1 is an external view showing an outline of a typical configuration example of the excavator 10.

The excavator 10 generally includes a lower frame 11 having a crawler, an upper frame 12 provided so as to be pivotable with respect to the lower frame 11, a boom 14 attached to the upper frame 12, and an arm 15 attached to the boom 14. And a bucket 16 attached to the arm 15. The

hydraulic cylinders

18, 19, and 20 are boom, arm, and bucket actuators that drive the boom 14, arm 15, and bucket 16, respectively. When the upper frame 12 is turned, the rotational driving force from the turning motor 13 is transmitted to the upper frame 12. When the hydraulic excavator 10 is caused to travel, the rotational driving force from the traveling motor 17 is transmitted to the crawler of the lower frame 11.

FIG. 2 is a cross-sectional view of the direction switching valve 30. The direction switching valve 30 is a valve that regulates the flow of hydraulic fluid supplied from the pump to the actuator and hydraulic fluid discharged from the actuator, and can selectively form a desired passage pattern from among a plurality of types of passage patterns. FIG. 2 shows the direction switching valve 30 disposed between the hydraulic cylinder 18 that is an actuator for driving the boom 14 shown in FIG. 1 and the first pump 51 and the second pump 52. Note that a direction switching valve disposed between another actuator (for example, a hydraulic cylinder 19 for driving the arm 15 and / or a hydraulic cylinder 20 for driving the bucket 16 shown in FIG. 1) and the pump, You may have the structure similar to the direction switching valve 30 shown in FIG.

The direction switching valve 30 includes a valve main body 31 in which a spool hole 33 is formed, and a spool 32 disposed in the spool hole 33.

The spool hole 33 is formed inside the valve body 31, and the spool 32 is slidably disposed. The slide drive system of the spool 32 is not particularly limited, and for example, a mechanical, hydraulic pilot type, or electromagnetic drive structure is used as the direction switching valve 30 in order to slide the spool 32 in the spool hole 33 and arrange it at a desired position. It is possible to adopt. The spool 32 is a substantially columnar member that is inserted into the spool hole 33, and includes a plurality of land portions that are spaced apart from each other in the axial direction and a plurality of notches provided between the land portions. The outer peripheral diameter of each land portion substantially coincides with the inner peripheral diameter of the spool hole 33. The outer peripheral diameter of each notch is smaller than the inner peripheral diameter of the spool hole 33. When each land portion is disposed between passages to be described later that open to the spool hole 33, the land portion blocks the spool hole 33 between these passages and blocks the flow of hydraulic oil. On the other hand, when each notch is disposed between passages, which will be described later, that open to the spool hole 33, it forms a flow path that connects these passages and allows the flow of hydraulic oil. In this way, the spool 32 can not only switch between connection and disconnection (that is, presence / absence of connection) between the passages, but can also adjust the flow path opening degree (that is, the valve opening degree) between the passages.

The valve body 31 is a block-shaped (lumped) member, and includes a first unload passage 34, a second unload passage 35, a first supply passage 36, a second supply passage 37, an actuator passage 40, a bridge passage 43, and a tank. A passage 58 is provided. Hydraulic fluid flows through these passages.

The first unload passage 34 communicates with the first pump 51, and the second unload passage 35 communicates with the second pump 52. The first supply passage 36 is in communication with the first pump 51, and the second supply passage 37 is in communication with the second pump 52. Specifically, an oil passage extending from the first pump 51 branches in the middle, and one of those oil passages constitutes a first unload passage 34 (particularly the upstream first unload passage 34a), and other oil One of the paths constitutes the first supply passage 36. Similarly, an oil passage extending from the second pump 52 branches in the middle, and one of those oil passages constitutes a second unload passage 35 (especially the upstream second unload passage 35a), and other oil passages. One constitutes the second supply passage 37.

The first unload passage 34 has an upstream first unload passage 34a and a downstream first unload passage 34b, and the second unload passage 35 has an upstream second unload passage 35a and a downstream second unload. A passage 35b is provided. The upstream first unload passage 34a and the upstream second unload passage 35a are upstream of the spool hole 33 (that is, the pump side), and the downstream first unload passage 34b and the downstream second unload passage 35a. The load passage 35 b is a passage on the downstream side (that is, the tank side) from the spool hole 33. In the present embodiment, the first unload passage 34 and the second unload passage 35 are arranged adjacent to each other with respect to the axial direction of the spool 32. That is, the downstream first unload passage 34b and the upstream second unload passage 35a are arranged adjacent to each other, and the upstream first unload passage 34a and the downstream first unload passage 34b are arranged next to each other, upstream. The side second unload passage 35a and the downstream second unload passage 35b are arranged adjacent to each other. In this way, by arranging the oil passages constituting the first unload passage 34 and the second unload passage 35 next to each other, the first unload passage 34 and the second unload passage 34 are utilized by using the common land portion of the spool 32. 2 The connection / cutoff of the unload passage 35 can be switched, and the axial length of the spool 32 and the spool hole 33 can be suppressed.

The first unload passage 34 and the second unload passage 35 are passages (bypass passages) for returning the hydraulic oil from the first pump 51 and the second pump 52 to the tank without supplying them to the actuator. In the present embodiment, as shown in FIG. 2, between each of the first unload passage 34 and the second unload passage 35 and the actuator passage 40 (that is, the first actuator passage 41 and the second actuator passage 42). One or more land portions of the spool 32 exist. Therefore, each of the first unload passage 34 and the second unload passage 35 does not directly communicate with the actuator passage 40 via the spool hole 33, but the first unload passage 34 and the second unload passage 34 The hydraulic oil is not directly supplied to or discharged from the actuator passage 40 from each of the load passages 35 via the spool holes 33. However, for example, when another oil passage branches from the first unload passage 34 and the second unload passage 35, the hydraulic oil may be supplied to the actuator from the first unload passage 34 and the second unload passage 35. Is possible. In the present embodiment, the upstream second unload passage 35a communicates with the second branch passage 49, and hydraulic oil from the upstream second unload passage 35a is supplied to the second branch passage 49, the bridge passage 43 (particularly, It is possible to supply the hydraulic cylinder 18 via the merging passage 45), the spool hole 33 and the actuator passage 40 (particularly the second actuator passage 42).

The first supply passage 36 and the second supply passage 37 are passages for supplying hydraulic oil from the first pump 51 and the second pump 52 to the actuator. The first supply passage 36 and the second supply passage 37 are not directly connected to the spool hole 33 but are connected to the spool hole 33 via the bridge passage 43. The first supply passage 36 of the present embodiment is directly connected to the first pump 51, but may be connected to the first pump 51 via the first unload passage 34. Similarly, the second supply passage 37 of the present embodiment is directly connected to the second pump 52, but may be connected to the second pump 52 via the second unload passage 35.

The bridge passage 43 is formed in a bridge shape and opens into the spool hole 33. The bridge passage 43 is formed between the first parallel passage 46, the second parallel passage 47, the first branch passage 48, and the second branch passage 49 and the spool hole 33. Intervene in. The bridge passage 43 is a passage for supplying hydraulic oil to the hydraulic cylinder 18 via the spool hole 33 and the actuator passage 40. When the bridge passage 43 is blocked by the land portion of the spool 32, the communication between the spool hole 33 and the actuator passage 40 and the bridge passage 43 is blocked or the valve opening degree is restricted. The bridge passage 43 of this embodiment has a communication passage 44 and a joining passage 45 that do not communicate with each other, and each of the communication passage 44 and the joining passage 45 opens into the spool hole 33 at a position different from each other.

The actuator passage 40 opens to the spool hole 33 and communicates with the hydraulic cylinder 18 that functions as an actuator for driving the boom 14. The actuator passage 40 of the present embodiment has a first actuator passage 41 and a second actuator passage 42. The first actuator passage 41 is disposed closer to the communication passage 44 of the merging passage 45 and the communication passage 44, and is connected to the first port 18 a of the hydraulic cylinder 18. The second actuator passage 42 is disposed closer to the joining passage 45 of the joining passage 45 and the communication passage 44 and is connected to the second port 18 b of the hydraulic cylinder 18.

The first port 18 a and the second port 18 b of the hydraulic cylinder 18 function as a supply port or a discharge port for the hydraulic oil to the hydraulic cylinder 18 according to the flow of the hydraulic oil determined based on the arrangement state of the spool 32. In the present embodiment, when the first port 18a functions as a discharge port and the second port 18b functions as a supply port, the hydraulic cylinder 18 is driven in the forward direction, and the piston of the hydraulic cylinder 18 protrudes from the cylinder. On the other hand, when the first port 18a functions as a supply port and the second port 18b functions as a discharge port, the hydraulic cylinder 18 is driven in the reverse direction, and the piston of the hydraulic cylinder 18 is drawn into the cylinder.

The tank passage 58 is a passage connected to a tank (see reference numeral “59” in FIGS. 3 and 4), and is a passage for returning the hydraulic oil discharged from the hydraulic cylinder 18 to the tank. Specifically, depending on the arrangement state of the spool 32, the tank passage 58 communicates with the first actuator passage 41 or the second actuator passage 42, or communicates with both the first actuator passage 41 and the second actuator passage 42. do not do.

The valve body 31 includes a first parallel region 53, a second parallel region 54, a first tandem region 55, and a second tandem region 56 in addition to the above-described passages.

The first parallel region 53 is a region in which a first parallel passage 46 that connects the first supply passage 36 and the bridge passage 43 (particularly the confluence passage 45) can be formed. The second parallel region 54 is a region in which a second parallel passage 47 that allows the second supply passage 37 and the bridge passage 43 (particularly the merge passage 45) to communicate with each other can be formed. The first tandem region 55 allows any one of the first supply passage 36 and the first unload passage 34 (particularly the upstream first unload passage 34a) to communicate with the bridge passage 43 (particularly the communication passage 44). This is a region where the first branch passage 48 can be formed. The first branch passage 48 of the present embodiment connects the first supply passage 36 and the communication passage 44. The second tandem region 56 allows any one of the second supply passage 37 and the second unload passage 35 (particularly the upstream second unload passage 35a) to communicate with the bridge passage 43 (particularly the junction passage 45). This is a region where the second branch passage 49 can be formed. The second branch passage 49 of the present embodiment connects the second unload passage 35 (that is, the upstream second unload passage 35a) and the merge passage 45.

The valve body 31 is a blocking portion 50 disposed between the communication passage 44 and the merging passage 45, and has a blocking portion 50 that divides the bridge passage 43 into the communication passage 44 and the merging passage 45. The blocking portion 50 closes one end portion (the right end portion in FIG. 2) of the communication passage 44 while closing one end portion (the left end portion in FIG. 2) of the merging passage 45. As a result, the communication passage 44 can communicate with the first branch passage 48 and the spool hole 33, but does not communicate with the merge passage 45. On the other hand, the merging passage 45 can communicate with the first parallel passage 46, the second parallel passage 47, the second branch passage 49, and the spool hole 33, but does not communicate with the communication passage 44.

A first check valve 61 is disposed in the first parallel passage 46, a second check valve 62 is disposed in the second parallel passage 47, a third check valve 63 is disposed in the first branch passage 48, and a second A fourth check valve 64 is disposed in the branch passage 49. The first check valve 61 is a valve that prevents the backflow of hydraulic oil from the merging passage 45 to the first parallel passage 46. The pressure of the hydraulic oil in the first parallel passage 46 is greater than the pressure of the hydraulic oil in the merging passage 45. Is larger, the first parallel passage 46 is not blocked. When the pressure of the hydraulic oil in the first parallel passage 46 is smaller than the pressure of the hydraulic oil in the merging passage 45, the first parallel passage 46 is blocked. Similarly, the second check valve 62 is a valve that prevents the backflow of hydraulic oil from the merging passage 45 to the second parallel passage 47, and the fourth check valve 64 is an operation from the merging passage 45 to the second branch passage 49. This valve prevents backflow of oil. On the other hand, the third check valve 63 is a valve that prevents the backflow of the hydraulic oil from the communication passage 44 to the first branch passage 48, and the pressure of the hydraulic oil in the first branch passage 48 reduces the hydraulic oil in the communication passage 44. When the pressure is higher than the pressure, the first branch passage 48 is not blocked, and when the pressure of the hydraulic oil in the first branch passage 48 is lower than the pressure of the hydraulic oil in the communication passage 44, the first branch passage 48 is blocked. Block it.

Each of the spool 32 and the

check valves

61, 62, 63, 64 described above is detachably attached to the valve body 31, and can be replaced with a member other than the configuration shown in FIG. 2 as necessary. May be. For example, another spool having a land portion and a notch portion different from the spool 32 shown in FIG. 2 may be disposed in the spool hole 33. Further, instead of one or more of the

check valves

61, 62, 63, 64, a member such as a plug that blocks the passage may be arranged. Thereby, the direction switching valve 30 can selectively form various passage patterns, and exhibits excellent general-purpose performance. For example, the directional switching valve 30 can supply hydraulic oil to the actuator from only one pump, or supply hydraulic oil to the actuator from two pumps. Further, the direction switching valve 30 can flexibly change and determine whether the oil passage connection mode is parallel connection or tandem connection. In addition, when it is desired to set priority regarding the supply of hydraulic oil to the oil passage, it is possible to form a throttle structure at a corresponding portion of the valve body 31 as necessary.

In the direction switching valve 30 having the above-described configuration, the spool 32 changes the communication state and the blocking state between the bridge passage 43 and the actuator passage 40 according to the arrangement position (that is, the stroke position) in the spool hole 33, The flow direction of hydraulic oil can be changed.

For example, FIG. 2 shows a state in which the spool 32 is disposed at the neutral position (that is, the “third position”). In this case, the spool 32 (particularly the land portion) shuts off the connection passage 44 and the actuator passage 40 (that is, the first actuator passage 41 and the second actuator passage 42), while the merging passage 45 and the actuator passage 40 (ie, the land portion). The first actuator passage 41 and the second actuator passage 42) are disconnected. Thus, the hydraulic oil from the first pump 51 and the second pump 52 does not flow into the spool hole 33 from the bridge passage 43 (that is, the communication passage 44 and the merging passage 45), and the actuator passage 40 (that is, the first actuator passage 41). And the hydraulic cylinder 18 is placed in a neutral state since it does not flow into the second actuator passage 42). In this case, each of the first actuator passage 41 and the second actuator passage 42 is blocked from the other flow paths to block the hydraulic oil, and the state of the hydraulic cylinder 18 is maintained.

Further, in the spool hole 33, the spool 32 is moved from the neutral position in one axial direction (see reference numeral “D1” in FIG. 2) to be arranged at the first operating position (ie, “first position”), or It is also possible to move it from the position in the other axial direction (see reference numeral “D2” in FIG. 2) and place it in the second operating position (ie, “second position”).

For example, when the spool 32 is disposed at the first operating position, a land portion of the spool 32 is disposed between the communication passage 44 and the first actuator passage 41, and between the junction passage 45 and the second actuator passage 42. Is provided with a notch portion of the spool 32. A notch portion of the spool 32 is disposed between the first actuator passage 41 and the tank passage 58, and a land portion of the spool 32 is disposed between the second actuator passage 42 and the tank passage 58. As a result, the spool 32 communicates the joining passage 45 with the actuator passage 40 (particularly the second actuator passage 42) via the spool hole 33, while the communication passage 44 and the actuator passage 40 (that is, the first actuator passage 41 and the second actuator passage). The passage between the passages 42) is blocked. Further, at least one of the first branch passage 48 (first flow passage) and the first parallel passage 46 (second flow passage) (the first parallel passage 46 in this example) and the second parallel passage 47 (first flow passage). 3 flow paths) and at least one of the second branch passages 49 (fourth flow paths) (in this example, at least the second branch passages 49) communicate with the merge passage 45. Thereby, at least one of the first supply passage 36 and the first unload passage 34 (the first supply passage 36 in this example), and at least one of the second supply passage 37 and the second unload passage 35. Either one (in this example, at least the second unload passage 35) communicates with the merging passage 45. Therefore, the hydraulic oil that has flowed from the first pump 51 into the merge passage 45 via the first supply passage 36 and the first parallel passage 46, and the upstream second unload passage 35 a and the second branch passage 49 from the second pump 52. The hydraulic oil that has flowed into the merging passage 45 via the merging flow merges in the merging passage 45 and flows into the second actuator passage 42 via the spool hole 33. The second parallel passage 47 is provided with a diaphragm (not shown) (see FIG. 3). Therefore, the flow rate of the hydraulic oil flowing from the second supply passage 37 into the merge passage 45 is limited by the restriction of the second parallel passage 47. As a result, the hydraulic cylinder 18 is supplied with hydraulic oil from the second actuator passage 42 and discharges the hydraulic oil to the tank passage 58 via the first actuator passage 41, and is driven in the forward direction. The forward driving here means driving for moving the boom 14, which requires higher power, among the driving for moving the boom 14 in the vertical direction.

On the other hand, when the spool 32 is disposed at the second operating position, a notch portion of the spool 32 is disposed between the communication passage 44 and the first actuator passage 41, and between the joining passage 45 and the second actuator passage 42. The land portion of the spool 32 is disposed in the center. A land portion of the spool 32 is disposed between the first actuator passage 41 and the tank passage 58, and a notch portion of the spool 32 is disposed between the second actuator passage 42 and the tank passage 58. As a result, the spool 32 blocks the connection passage 44 through the spool hole 33 and the actuator passage 40 (particularly the first passage) while blocking between the merging passage 45 and the actuator passage 40 (the first actuator passage 41 and the second actuator passage 42). 1 actuator passage 41). In addition, at least one of the first branch passage 48 (first flow path) and the first parallel path 46 (second flow path) (the first branch passage 48 in this example) is communicated with the communication passage 44. The As a result, at least one of the first unload passage 34 and the first supply passage 36 (in this example, the first supply passage 36) communicates with the communication passage 44. Therefore, the hydraulic oil that has flowed from the first pump 51 into the communication passage 44 through the first supply passage 36 and the first branch passage 48 flows into the first actuator passage 41 through the spool hole 33. As a result, the hydraulic cylinder 18 is supplied with hydraulic oil from the first actuator passage 41 and discharges hydraulic oil to the second actuator passage 42 and is driven in the reverse direction. The driving in the reverse direction referred to here means driving for moving the boom 14 that requires smaller power downward, among driving for moving the boom 14 in the vertical direction.

Next, driving states of the first pump 51, the second pump 52, the direction switching valve 30, and the hydraulic cylinder 18 will be described with reference to the hydraulic circuit diagrams of FIGS.

FIG. 3 is a hydraulic circuit diagram of the excavator 10, and particularly shows a case where the boom 14 is raised by driving the hydraulic cylinder 18 in the forward direction. FIG. 4 is a hydraulic circuit diagram of the excavator 10, and particularly shows a case where the boom 14 is lowered by driving the hydraulic cylinder 18 in the reverse direction. 3 and 4, not only the hydraulic circuit for the hydraulic cylinder 18 that drives the boom 14, but also the hydraulic circuit for the swing motor 13, the hydraulic circuit for the hydraulic cylinder 19 that drives the arm 15, and A hydraulic circuit for the hydraulic cylinder 20 that drives the bucket 16 is also shown. In the following, the hydraulic circuit of the hydraulic cylinder 18 that drives the boom 14 will be mainly described. Therefore, the

direction switching valves

70, 71, 72 provided for the swing motor 13, the hydraulic cylinder 19, and the hydraulic cylinder 20 are shown in FIGS. At 4, it is neutral.

When driving the hydraulic cylinder 18 in the forward direction to raise the boom 14, the spool 32 is disposed at the first operating position as described above. In this case, the direction switching valve 30 has the circuit configuration shown in FIG. 3, and the first pump 51 and the second pump 52 and the hydraulic cylinder 18 are connected by an oil passage denoted by reference numeral “30b”.

That is, the oil passage extending from the first pump 51 is branched halfway to form the first supply passage 36, and the first parallel passage 46 branched from the first supply passage 36 communicates with the merge passage 45. On the other hand, an upstream second unload passage 35 a is formed by an oil passage extending from the second pump 52, and a second branch passage 49 branched from the upstream second unload passage 35 a communicates with the merge passage 45. A throttle and a second check valve 62 are provided in the second parallel passage 47 branched from the second supply passage 37, and the second parallel passage 47 also communicates with the merging passage 45. The junction passage 45 is communicated with the second actuator passage 42, and the second actuator passage 42 is connected to the second port 18 b of the hydraulic cylinder 18. The first actuator passage 41 connected to the first port 18 a of the hydraulic cylinder 18 is connected to the tank passage 58, and the tank passage 58 is connected to the tank 59.

According to the hydraulic circuit having the above-described configuration, the hydraulic oil from the first pump 51 and the hydraulic oil from the second pump 52 are merged in the merging passage 45 and supplied to the hydraulic cylinder 18 via the second actuator passage 42. Is done. The hydraulic oil flowing out from the hydraulic cylinder 18 is discharged to the tank 59 through the first actuator passage 41 and the tank passage 58. Thereby, the hydraulic cylinder 18 is driven in the forward direction, and the boom 14 is raised.

On the other hand, when the hydraulic cylinder 18 is driven in the reverse direction to lower the boom 14, the spool 32 is disposed at the second operating position as described above. In this case, the direction switching valve 30 has the circuit configuration shown in FIG. 4, and the first pump 51 and the second pump 52 and the hydraulic cylinder 18 are connected by an oil passage denoted by reference numeral “30c”.

That is, an oil passage extending from the first pump 51 is branched halfway to form a first supply passage 36, and a first branch passage 48 is branched from the first supply passage 36, and the first branch passage 48 communicates. The first actuator passage 41 is communicated with the passage 44. On the other hand, the oil passage extending from the second pump 52 is blocked by the direction switching valve 30 and does not communicate with the actuator passage 40 (that is, the first actuator passage 41 and the second actuator passage 42). The second actuator passage 42 is connected to the tank 59 via the tank passage 58.

According to the hydraulic circuit having the above-described configuration, the hydraulic oil from the first pump 51 is supplied to the hydraulic cylinder 18 via the first supply passage 36, the first branch passage 48, the communication passage 44, and the first actuator passage 41. However, the hydraulic oil from the second pump 52 is not supplied to the hydraulic cylinder 18. The hydraulic oil flowing out from the hydraulic cylinder 18 is discharged to the tank 59 through the second actuator passage 42 and the tank passage 58. As a result, the hydraulic cylinder 18 is driven in the reverse direction, and the boom 14 is lowered.

When the boom 14 is not raised or lowered, the spool 32 is disposed at the neutral position as described above, and the oil path between the first pump 51 and the second pump 52 and the hydraulic cylinder 18 is shown in FIG. This is configured as indicated by reference numeral “30a” in FIG. That is, the first pump 51 and the second pump 52 and the actuator passage 40 (that is, the first actuator passage 41 and the second actuator passage 42) are blocked by the direction switching valve 30, and the hydraulic oil is supplied to the hydraulic cylinder 18. There is no discharge.

As described above, according to this embodiment, the supply flow rate of hydraulic oil to the hydraulic cylinder 18 can be changed by the direction switching valve 30 having a simple structure. In particular, in the direction switching valve 30 of the present embodiment, the hydraulic cylinder 18 supplies a desired amount of hydraulic oil corresponding to the operating state of the hydraulic cylinder 18 only by dividing the bridge passage 43 into the communication passage 44 and the junction passage 45 by the blocking portion 50. Can be supplied to. That is, when the hydraulic cylinder 18 is driven in a forward direction that requires a large amount of hydraulic fluid, hydraulic fluid can be supplied to the hydraulic cylinder 18 from two pumps (that is, the first pump 51 and the second pump 52). it can. On the other hand, when the amount of hydraulic oil supplied to the hydraulic cylinder 18 is sufficiently low and the reverse drive is sufficient, the hydraulic oil can be supplied to the hydraulic cylinder 18 only from one pump (that is, the first pump 51).

Thus, the supply mode of the hydraulic oil can be optimized according to the driving state of the hydraulic cylinder 18, and the energy efficiency can be improved.

In the above-described embodiment, the direction switching valve 30 that restricts the supply and discharge of the hydraulic oil to and from the hydraulic cylinder 18 for driving the boom 14 has the configuration shown in FIG. , 71 and 72 (particularly the

direction switching valves

71 and 72 for regulating the supply and discharge of hydraulic oil to and from the

hydraulic cylinders

19 and 20 for driving the arm 15 and the bucket 16) have the configuration shown in FIG. Good.

The present invention is not limited to the above-described embodiments and modifications. For example, various modifications may be made to the elements of the above-described embodiments and modifications. In addition, embodiments including components other than the above-described components are also included in the embodiments of the present invention. Further, a form in which some of the above-described components are not included is also included in the embodiment of the present invention. Therefore, the constituent elements included in each of the embodiments and modifications described above and the embodiments of the present invention other than those described above may be combined with each other, and embodiments related to such combinations are also included in the embodiments of the present invention. . Moreover, the effect produced by the present invention is not limited to the above-described effect, and a specific effect corresponding to the specific configuration of each embodiment can be exhibited. As described above, various additions, modifications, and partial deletions may be made to each element described in the claims, the description, the abstract, and the drawings without departing from the technical idea and spirit of the present invention. It is.

For example, the merging passage 45 only needs to communicate with one of the first branch passage 48 and the first parallel passage 46 and at least one of the second parallel passage 47 and the second branch passage 49. The communication passage 44 only needs to communicate with the other of the first branch passage 48 and the first parallel passage 46. However, also in this case, the communication passage 44 does not communicate with the merge passage 45.

DESCRIPTION OF SYMBOLS 10 ... Hydraulic excavator, 11 ... Lower frame, 12 ... Upper frame, 13 ... Turning motor, 14 ... Boom, 15 ... Arm, 16 ... Bucket, 17 ... Traveling motor, 18 ... Hydraulic cylinder, 18a ... First port, 18b ... 2nd port, 19 ... hydraulic cylinder, 20 ... hydraulic cylinder, 30 ... directional switching valve, 30a ... neutral position, 30b ... first operating position, 30c ... second operating position, 31 ... valve body, 32 ... spool, 33 ... Spool hole 34 ... first unload passage 34a ... upstream first unload passage 34b downstream first unload passage 35 ... second unload passage 35a upstream second unload passage 35b ... downstream second unload passage, 36 ... first supply passage, 37 ... second supply passage, 40 ... actuator passage, 41 ... first actuator passage, 42 ... second accelerator Numerator passage, 43 ... Bridge passage, 44 ... Communication passage, 45 ... Junction passage, 46 ... First parallel passage (second passage), 47 ... Second parallel passage (third passage), 48 ... First branch passage (First flow path), 49 ... second branch passage (fourth flow path), 50 ... blocking section, 51 ... first pump, 52 ... second pump, 53 ... first parallel area, 54 ... second parallel area 55 ... first tandem region, 56 ... second tandem region, 58 ... tank passage, 59 ... tank, 61 ... first check valve, 62 ... second check valve, 63 ... third check valve, 64 ... fourth check Valve, 70 ... Direction switching valve, 71 ... Direction switching valve, 72 ... Direction switching valve

Claims

A valve body in which a spool hole is formed;
A spool disposed in the spool hole;
A bridge passage formed in a bridge shape and opened to the spool hole, the bridge passage being divided into a merging passage and a communication passage by a blocking portion;
A first flow path, a second flow path, a third flow path, and a fourth flow path formed in the valve body,
The first flow path and the second flow path are communicated with a first pump;
The third flow path and the fourth flow path are communicated with a second pump,
When the spool is disposed at the first position, at least one of the first flow path and the second flow path, and at least one of the third flow path and the fourth flow path. One is communicated with the merging passage,
A direction switching valve in which at least one of the first flow path and the second flow path is communicated with the communication path when the spool is disposed at the second position.
The valve body has an actuator passage that opens into the spool hole and communicates with the actuator,
At least one of the first flow path and the second flow path and at least one of the third flow path and the fourth flow path communicates with the merge passage;
The communication path communicates with the other of the first flow path and the second flow path but does not communicate with the merge path,
The spool changes a communication state and a blocking state between the bridge passage and the actuator passage according to an arrangement position in the spool hole,
When the spool is disposed at the first position, the spool blocks the connection between the communication passage and the actuator passage while communicating the merging passage with the actuator passage through the spool hole. And
When the spool is disposed at the second position, the spool communicates the communication passage with the actuator passage through the spool hole while blocking between the merging passage and the actuator passage. The direction switching valve according to claim 1 to be made.
3. The direction switching valve according to claim 2, wherein the blocking portion closes one end of the connecting passage while closing one end of the merging passage.
The actuator passage is disposed closer to the junction passage of the junction passage and the communication passage and closer to the junction passage of the junction passage and the communication passage. 2 actuator passages,
When the spool is disposed at the first position, the spool communicates the merging passage with the second actuator passage through the spool hole, and the communication passage and the first actuator passage. Block between
When the spool is disposed at the second position, the spool blocks the communication passage through the spool hole while blocking between the merging passage and the second actuator passage. The direction switching valve according to claim 2 or 3, wherein the direction switching valve communicates with the actuator passage.
3. When the spool is disposed at the third position, the spool blocks between the junction path and the actuator path while blocking between the communication path and the actuator path. The direction switching valve according to any one of 1 to 4.
A first check valve that prevents backflow of hydraulic oil from the merging passage to the second flow path, a second check valve that prevents backflow of hydraulic oil from the merging path to the third flow path, and A third check valve that prevents backflow of hydraulic oil to one flow path and a fourth check valve that prevents backflow of hydraulic oil from the merging passage to the fourth flow path are further provided. The direction switching valve according to any one of 2 to 5.
The direction switching valve according to any one of claims 2 to 6, wherein the actuator is a hydraulic cylinder.
The direction switching valve according to any one of claims 2 to 7, wherein the actuator is an actuator for driving a boom.