JP6755814B2 - Direction switching valve - Google Patents

Description

The present invention relates to a directional control valve that regulates the flow of hydraulic oil.

Hydraulic circuit systems are known in which various actuators are driven by hydraulic oil (ie, pressure oil) supplied from two pumps. In such a hydraulic circuit system, the flow of hydraulic oil from the two pumps is regulated by a directional control valve, and the operation of each actuator is controlled.

Patent Document 1 discloses a directional control valve capable of selectively forming a plurality of types of passage patterns. In this direction switching valve, a plurality of types of passage patterns can be selectively formed by arranging a check valve, a plug, or the like between each of the tandem passage and the parallel passage and the bridge passage.

Japanese Unexamined Patent Publication No. 2016-138619

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 especially during ascending driving. For example, when raising the boom, it is necessary to supply a relatively large flow rate of hydraulic oil 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, the potential energy of the boom can be used, so that it is sufficient to supply a relatively small flow rate of hydraulic oil to the hydraulic cylinder.

As described above, the flow rate of the hydraulic oil required to drive the actuator is not always constant and changes depending on the specific operating state. Therefore, it is preferable to adjust the flow rate of the hydraulic oil supplied to the hydraulic cylinder by the above-mentioned direction switching valve according to the specific operating state of the actuator. However, it is not easy to realize such a directional control valve with a simple structure, and mere addition of a flow path, a valve, a plug, etc. complicates the structure of the directional control valve and leads to an increase in cost.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a direction 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 body in which a spool hole is formed, a spool arranged in the spool hole, and a bridge passage formed in a bridge shape and opened in the spool hole, and a confluence passage and a connecting passage by a blocking portion. It is provided with a bridge passage divided into the above, a first flow path, a second flow path, a third flow path and a fourth flow path formed in the valve body, and the first flow path and the second flow path are the first flow paths. When communicated with the 1st pump, the 3rd and 4th flow paths are communicated with the 2nd pump, and the spool is arranged at the 1st position, at least one of the 1st flow path and the 2nd flow path. When one and at least one of the third flow path and the fourth flow path are communicated with the merging passage and the spool is arranged at the second position, the first flow path and the second flow path It relates to a direction switching valve in which at least one of them is communicated with a connecting passage.

The valve body has an actuator passage that opens into the spool hole and communicates with the actuator, and at least one of the first and second passages and the third and fourth passages. One communicates with the merging passage, the connecting passage communicates with the other of the first and second passages but not with the merging passage, and the spool is connected to the bridge passage according to the arrangement position in the spool hole. When the communication state and the cutoff state with the actuator passage are changed and the spool is arranged in the first position, the spool communicates with the connecting passage while communicating the merging passage with the actuator passage through the spool hole. When the spool is placed in the second position by blocking from the actuator passage, the spool makes the connecting passage into the actuator passage through the spool hole while blocking between the merging passage and the actuator passage. It may be communicated.

Another aspect of the present invention includes a valve body in which a spool hole is formed and a spool arranged in the spool hole, and the valve body includes a first unload passage that communicates with a first pump and a second. The second unload passage that communicates with the pump, the first supply passage that communicates with the first pump, the second supply passage that communicates with the second pump, and the actuator that opens in the spool hole and communicates with the actuator. A second parallel region capable of forming a first parallel passage connecting the passage, a bridge passage opening in the spool hole, the first supply passage and the bridge passage, and a second connecting the second supply passage and the bridge passage. A second parallel region in which a parallel passage can be formed, a first branch passage that connects one of the first supply passage and the first unload passage with the bridge passage, and a second supply passage and a second unload. It has a second branch passage that communicates one of the passages with the bridge passage, and the bridge passage communicates with the first parallel passage and the confluence passage that communicates with the second parallel passage and the first branch passage. However, it has a connecting passage that does not communicate with the confluence passage, and the spool changes the communication state and the cutoff state between the bridge passage and the actuator passage according to the arrangement position in the spool hole, and the spool is the first. When placed in the position, the spool cuts off between the connecting passage and the actuator passage while communicating the merging passage with the actuator passage through the spool hole, and the spool is placed in the second position. In this case, the spool relates to a directional switching valve that connects the connecting passage to the actuator passage through the spool hole while blocking between the merging passage and the actuator passage.

The blocking portion may block one end of the connecting passage while closing one end of the confluence passage.

The actuator passage includes a first actuator passage which is arranged closer to the connecting passage among the merging passage and the connecting passage, and a second actuator passage which is arranged closer to the merging passage among the merging passage and the connecting passage. However, when the spool is arranged in the first position, the spool cuts off between the connecting passage and the first actuator passage while communicating the merging passage with the second actuator passage through the spool hole. When the spool is arranged in the second position, the spool may communicate the connecting passage to the first actuator passage through the spool hole while blocking between the merging passage and the second actuator passage. ..

When the spool is placed in the third position, the spool may block between the confluence passage and the actuator passage while blocking between the connecting passage and the actuator passage.

The direction switching valves are the first check valve that prevents the backflow of hydraulic oil from the merging passage to the second flow path, the second check valve that prevents the backflow of hydraulic oil from the merging passage to the third flow path, and the first from the connecting passage. At least one of a third check valve that prevents the backflow of the hydraulic oil into the flow path and a fourth check valve that prevents the backflow of the hydraulic oil from the merging passage to the fourth flow path may be further provided.

The actuator may be a hydraulic cylinder.

The actuator may be an actuator for driving the boom.

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

FIG. 1 is an external view showing an outline of a typical configuration example of a hydraulic excavator. FIG. 2 is a cross-sectional view of the direction switching valve. FIG. 3 shows a hydraulic circuit diagram of a hydraulic excavator, and particularly shows a case where a hydraulic cylinder is driven in the forward direction to raise a boom. FIG. 4 shows a hydraulic circuit diagram of a hydraulic excavator, and particularly shows a case where a hydraulic cylinder is driven in the opposite direction to lower the boom.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following, a case where the present invention is applied to a hydraulic excavator, particularly to a directional control valve used in a hydraulic circuit for driving a boom will be described. However, the object to which the present invention can be applied is not limited to the directional control 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 hydraulic excavator 10.

The hydraulic excavator 10 generally includes a lower frame 11 provided with a crawler, an upper frame 12 rotatably provided 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. , A bucket 16 attached to the arm 15. The hydraulic cylinders 18, 19 and 20 are actuators for a boom, an arm and a bucket, and drive the boom 14, the arm 15 and the bucket 16, respectively. When the upper frame 12 is swiveled, the rotational driving force from the swivel motor 13 is transmitted to the upper frame 12. When the hydraulic excavator 10 is driven, 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 directional control valve 30 is a valve that regulates the flow of the hydraulic oil supplied from the pump to the actuator and the hydraulic oil discharged from the actuator, and can selectively form a desired passage pattern from a plurality of types of passage patterns. FIG. 2 shows a direction switching valve 30 arranged between the hydraulic cylinder 18, which is an actuator for driving the boom 14 shown in FIG. 1, and the first pump 51 and the second pump 52. A direction switching valve arranged between the pump and another actuator (for example, the hydraulic cylinder 19 for driving the arm 15 shown in FIG. 1 and / or the hydraulic cylinder 20 for driving the bucket 16) is provided. It may have the same configuration as the direction switching valve 30 shown in FIG.

The directional control valve 30 includes a valve body 31 in which the spool hole 33 is formed, and a spool 32 arranged in the spool hole 33.

The spool hole 33 is formed inside the valve body 31, and the spool 32 is slidably arranged. The slide drive method of the spool 32 is not particularly limited, and in order to slide the spool 32 in the spool hole 33 and arrange it at a desired position, for example, a mechanical, hydraulic pilot type or electromagnetic drive structure may be used in the direction switching valve 30. It is possible to adopt. The spool 32 is a substantially columnar member inserted into the spool hole 33, and has a plurality of land portions arranged 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 arranged between the passages to be described later that open in the spool holes 33, the spool holes 33 between these passages are closed to block the flow of hydraulic oil. On the other hand, when each notch is arranged between the passages to be described later which open in the spool hole 33, it forms a passage connecting these passages and allows the flow of hydraulic oil. The spool 32 can not only switch the connection and disconnection (that is, the presence / absence of connection) between the passages in this way, but also adjust the flow path opening degree (that is, the valve opening degree) between the passages.

The valve body 31 is a block-shaped (lump-shaped) member, and is 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. It has a passage 58. Hydraulic oil is flushed 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 communicates with the first pump 51, and the second supply passage 37 communicates with the second pump 52. Specifically, the oil passage extending from the first pump 51 branches in the middle, and one of those oil passages constitutes the first unload passage 34 (particularly, the upstream side first unload passage 34a), and the other oil. One of the roads constitutes the first supply passage 36. Similarly, the oil passages extending from the second pump 52 branch off in the middle, and one of those oil passages constitutes the second unload passage 35 (particularly the upstream side second unload passage 35a), and the other oil passages. One constitutes the second supply passage 37.

The first unload passage 34 has an upstream side first unload passage 34a and a downstream side first unload passage 34b, and the second unload passage 35 has an upstream side second unload passage 35a and a downstream side second unload. It has a passage 35b. The upstream side first unload passage 34a and the upstream side second unload passage 35a are passages on the upstream side (that is, the pump side) of the spool hole 33, and the downstream side first unload passage 34b and the downstream side second unload. The load passage 35b is a passage on the downstream side (that is, the tank side) of 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 in 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 adjacent to each other. The side second unload passage 35a and the downstream side second unload passage 35b are arranged adjacent to each other. By arranging the oil passages constituting the first unload passage 34 and the second unload passage 35 next to each other in this way, the first unload passage 34 and the first unload passage 34 and the first unload passage 34 and the first unload passage 34 and the first unload passage 34 are used by using the common land portion of the spool 32. 2 The connection / disconnection of the unload passage 35 can be switched, and the lengthening of the spool 32 and the spool hole 33 in the axial direction 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 the actuator 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). , There is one or more land portions of the spool 32. Therefore, each of the first unload passage 34 and the second unload passage 35 does not directly communicate with the actuator passage 40 through the spool hole 33, and the first unload passage 34 and the second unload are not directly communicated with each other. The hydraulic oil is not directly supplied to and discharged from each of the load passages 35 to the actuator passage 40 via the spool hole 33. However, for example, when another oil passage branches from the first unload passage 34 and the second unload passage 35, hydraulic oil may be supplied to the actuator from the first unload passage 34 and the second unload passage 35. It is possible. In the present embodiment, the upstream side second unload passage 35a communicates with the second branch passage 49, and the hydraulic oil from the upstream side second unload passage 35a is supplied to the second branch passage 49 and 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. Although the first supply passage 36 of the present embodiment is directly connected to the first pump 51, it may be connected to the first pump 51 via the first unload passage 34. Similarly, although the second supply passage 37 of the present embodiment is directly connected to the second pump 52, it 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 in the spool hole 33, and is between each of 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 cut off or the valve opening degree is limited. The bridge passage 43 of the present embodiment has a connecting passage 44 and a merging passage 45 that do not communicate with each other, and each of the connecting passage 44 and the merging passage 45 opens into the spool hole 33 at a position different from each other.

The actuator passage 40 opens in the spool hole 33 and communicates with a 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 arranged closer to the connecting passage 44 among the merging passage 45 and the connecting passage 44, and is connected to the first port 18a of the hydraulic cylinder 18. The second actuator passage 42 is arranged closer to the merging passage 45 of the merging passage 45 and the connecting passage 44, and is connected to the second port 18b of the hydraulic cylinder 18.

The first port 18a and the second port 18b of the hydraulic cylinder 18 function as a supply port or a discharge port of 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 an 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 opposite direction, and the piston of the hydraulic cylinder 18 is pulled into the cylinder.

The tank passage 58 is a passage connected to the tank (see the symbol “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, 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, depending on the arrangement state of the spool 32. do not do.

Further, the valve body 31 has 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-mentioned passages.

The first parallel region 53 is an region capable of forming a first parallel passage 46 that communicates the first supply passage 36 and the bridge passage 43 (particularly, the merging passage 45). The second parallel region 54 is an region capable of forming a second parallel passage 47 that communicates the second supply passage 37 and the bridge passage 43 (particularly, the merging passage 45). The first tandem area 55 communicates one of the first supply passage 36 and the first unload passage 34 (particularly the upstream first unload passage 34a) with the bridge passage 43 (particularly the connecting passage 44). This is a region where the first branch passage 48 can be formed. The first branch passage 48 of the present embodiment communicates the first supply passage 36 with the connecting passage 44. The second tandem area 56 communicates one of the second supply passage 37 and the second unload passage 35 (particularly the upstream second unload passage 35a) with the bridge passage 43 (particularly the confluence passage 45). This is a region where the second branch passage 49 can be formed. The second branch passage 49 of the present embodiment communicates the second unload passage 35 (that is, the upstream side second unload passage 35a) with the confluence passage 45.

The valve body 31 is a blocking portion 50 arranged between the connecting passage 44 and the merging passage 45, and has a blocking portion 50 that divides the bridge passage 43 into the connecting passage 44 and the merging passage 45. The blocking portion 50 closes one end of the confluence passage 45 (the left end of FIG. 2) and one end of the connecting passage 44 (the right end of FIG. 2). As a result, the connecting passage 44 can communicate with the first branch passage 48 and the spool hole 33, but does not communicate with the merging 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 connecting passage 44.

The first check valve 61 is arranged in the first parallel passage 46, the second check valve 62 is arranged in the second parallel passage 47, the third check valve 63 is arranged in the first branch passage 48, and the second check valve 63 is arranged. A fourth check valve 64 is arranged in the branch passage 49. The first check valve 61 is a valve for preventing backflow of hydraulic oil from the merging passage 45 to the first parallel passage 46, and the pressure of the hydraulic oil in the first parallel passage 46 is higher than the pressure of the hydraulic oil in the merging passage 45. If it is too large, the first parallel passage 46 is not blocked, and if 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 operates from the merging passage 45 to the second branch passage 49. A valve that prevents backflow of oil. On the other hand, the third check valve 63 is a valve for preventing the backflow of hydraulic oil from the connecting passage 44 to the first branch passage 48, and the pressure of the hydraulic oil in the first branch passage 48 is the pressure of the hydraulic oil in the connecting passage 44. When the pressure is larger 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 smaller than the pressure of the hydraulic oil in the connecting passage 44, the first branch passage 48 is opened. Close.

Each of the spool 32 and the check valves 61, 62, 63, and 64 described above is detachably provided with respect to the valve body 31, and is replaced with a member other than the configuration shown in FIG. 2 as necessary. You may. For example, another spool having a land portion and a notch portion different from the spool 32 shown in FIG. 2 may be arranged in the spool hole 33. Further, instead of one or a plurality of check valves 61, 62, 63, 64, a member such as a plug for blocking the passage may be arranged. As a result, the directional control valve 30 can selectively form various passage patterns and exhibits excellent general-purpose performance. For example, the directional control valve 30 makes it possible to supply hydraulic oil to the actuator from only one pump or to supply hydraulic oil to the actuator from two pumps. Further, the direction switching valve 30 can flexibly change and determine whether the connection mode of the oil passage is parallel connection or tandem connection. Further, when it is desired to set a 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 directional control valve 30 having the above configuration, the spool 32 changes the communication state and the cutoff 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 the hydraulic oil can be changed.

For example, FIG. 2 shows a state in which the spool 32 is arranged in a neutral position (that is, a "third position"). In this case, the spool 32 (particularly the land portion) cuts off between the connecting 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 (that is, the actuator passage 40). The space between the first actuator passage 41 and the second actuator passage 42) is cut off. As a result, 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 connecting passage 44 and the merging passage 45), and the actuator passage 40 (that is, the first actuator passage 41) does not flow. The hydraulic cylinder 18 is placed in a neutral state because 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 passages 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 the sign “D1” in FIG. 2) to be placed in the first operating position (that is, the “first position”), or is neutral. It can also be moved from one position to the other axial direction (see sign "D2" in FIG. 2) and placed in a second operating position (ie, "second position").

For example, when the spool 32 is arranged at the first operating position, a land portion of the spool 32 is arranged between the connecting passage 44 and the first actuator passage 41, and between the merging passage 45 and the second actuator passage 42. Is arranged with a notch in the spool 32. Further, a notch portion of the spool 32 is arranged between the first actuator passage 41 and the tank passage 58, and a land portion of the spool 32 is arranged between the second actuator passage 42 and the tank passage 58. As a result, the spool 32 communicates the merging passage 45 with the actuator passage 40 (particularly the second actuator passage 42) via the spool hole 33, while communicating the connecting passage 44 and the actuator passage 40 (that is, the first actuator passage 41 and the second actuator). It is cut off from the passage 42). Further, at least one of the first branch passage 48 (first flow path) and the first parallel passage 46 (second flow path) (first parallel passage 46 in this example) and the second parallel passage 47 (first parallel passage 47). At least one of the three passages) and the second branch passage 49 (fourth passage) (at least the second branch passage 49 in this example) is communicated with the confluence passage 45. As a result, 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. One of them (at least the second unload passage 35 in this example) is communicated with the confluence passage 45. Therefore, the hydraulic oil that has flowed from the first pump 51 into the confluence passage 45 via the first supply passage 36 and the first parallel passage 46, and the second unload passage 35a and the second branch passage 49 on the upstream side from the second pump 52. The hydraulic oil that has flowed into the merging passage 45 through the merging passage 45 merges at the merging passage 45 and flows into the second actuator passage 42 through the spool hole 33. The second parallel passage 47 is provided with a diaphragm (see FIG. 3) (not shown). Therefore, the flow rate of the hydraulic oil flowing from the second supply passage 37 into the merging passage 45 is limited by the throttle of the second parallel passage 47. As a result, the hydraulic cylinder 18 is driven in the forward direction by supplying hydraulic oil from the second actuator passage 42 and discharging the hydraulic oil to the tank passage 58 via the first actuator passage 41. The forward drive as used herein means a drive for moving the boom 14 in the vertical direction, which requires a larger power, in the upward direction.

On the other hand, when the spool 32 is arranged at the second operating position, a notch portion of the spool 32 is arranged between the connecting passage 44 and the first actuator passage 41, and between the merging passage 45 and the second actuator passage 42. The land portion of the spool 32 is arranged in. Further, a land portion of the spool 32 is arranged between the first actuator passage 41 and the tank passage 58, and a notch portion of the spool 32 is arranged between the second actuator passage 42 and the tank passage 58. As a result, the spool 32 cuts between the merging passage 45 and the actuator passage 40 (the first actuator passage 41 and the second actuator passage 42), and connects the connecting passage 44 through the spool hole 33 to the actuator passage 40 (particularly the first actuator passage 40). 1 Communicate with the actuator passage 41). Further, at least one of the first branch passage 48 (first flow path) and the first parallel passage 46 (second flow path) (the first branch passage 48 in this example) is communicated with the connecting passage 44. To. As a result, at least one of the first unload passage 34 and the first supply passage 36 (the first supply passage 36 in this example) is communicated with the connecting passage 44. Therefore, the hydraulic oil that has flowed from the first pump 51 into the connecting passage 44 via 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 driven in the opposite direction by supplying hydraulic oil from the first actuator passage 41 and discharging the hydraulic oil to the second actuator passage 42. The drive in the reverse direction as used herein means a drive for moving the boom 14 in the vertical direction, which requires a smaller power, in the downward direction.

Next, the drive states of the first pump 51, the second pump 52, the directional control valve 30, and the hydraulic cylinder 18 will be described with reference to the hydraulic circuit diagrams of FIGS. 3 and 4.

FIG. 3 shows a hydraulic circuit diagram of the hydraulic excavator 10, and particularly shows a case where the hydraulic cylinder 18 is driven in the forward direction to raise the boom 14. FIG. 4 shows a hydraulic circuit diagram of the hydraulic excavator 10, and particularly shows a case where the hydraulic cylinder 18 is driven in the opposite direction to lower the boom 14. 3 and 4 show not only the hydraulic circuit for the hydraulic cylinder 18 that drives the boom 14, but also the hydraulic circuit for the swivel 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. Since the hydraulic circuit of the hydraulic cylinder 18 that mainly drives the boom 14 will be described below, the direction switching valves 70, 71, and 72 provided for the swivel motor 13, the hydraulic cylinder 19, and the hydraulic cylinder 20 are shown in FIGS. In 4, it is placed in a neutral state.

When the hydraulic cylinder 18 is driven in the forward direction to raise the boom 14, the spool 32 is arranged at the first operating position as described above. In this case, the directional control 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 represented by the reference numeral “30b”.

That is, the oil passage extending from the first pump 51 branches in the middle to form the first supply passage 36, and the first parallel passage 46 branching from the first supply passage 36 communicates with the confluence passage 45. On the other hand, the upstream side second unload passage 35a is formed by the oil passage extending from the second pump 52, and the second branch passage 49 branching from the upstream side second unload passage 35a communicates with the confluence passage 45. A throttle and a second check valve 62 are provided in the second parallel passage 47 branching from the second supply passage 37, and the second parallel passage 47 also communicates with the confluence passage 45. Then, the merging passage 45 is communicated with the second actuator passage 42, and the second actuator passage 42 is connected to the second port 18b of the hydraulic cylinder 18. The first actuator passage 41 connected to the first port 18a of the hydraulic cylinder 18 is communicated with 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 merge in the merging passage 45 and are supplied to the hydraulic cylinder 18 via the second actuator passage 42. Will be done. Further, the hydraulic oil flowing out from the hydraulic cylinder 18 is discharged to the tank 59 via the first actuator passage 41 and the tank passage 58. As a result, 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 opposite direction to lower the boom 14, the spool 32 is arranged 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 represented by the reference numeral “30c”.

That is, the oil passage extending from the first pump 51 branches in the middle to form the first supply passage 36, the first branch passage 48 branches from the first supply passage 36, and the first branch passage 48 communicates with each other. It communicates with the first actuator passage 41 via 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). Then, 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 connecting 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. Further, the hydraulic oil flowing out from the hydraulic cylinder 18 is discharged to the tank 59 via the second actuator passage 42 and the tank passage 58. As a result, the hydraulic cylinder 18 is driven in the opposite direction, and the boom 14 is lowered.

When the boom 14 is neither raised nor lowered, the spool 32 is arranged in the neutral position as described above, and the oil passage between the first pump 51 and the second pump 52 and the hydraulic cylinder 18 is shown in FIG. It is configured as shown by the 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 also supplied to the hydraulic cylinder 18. No discharge is done.

As described above, according to the present embodiment, the flow rate of hydraulic oil supplied 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 bridge passage 43 is simply divided into the connecting passage 44 and the merging passage 45 by the shutoff portion 50, and a desired amount of hydraulic oil according to the operating state of the hydraulic cylinder 18 is supplied to the hydraulic cylinder 18. Can be supplied to. That is, when the hydraulic cylinder 18 is driven in the forward direction, which requires a large flow rate of hydraulic oil, the hydraulic oil 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 small and sufficient in the reverse direction, the hydraulic oil can be supplied to the hydraulic cylinder 18 only from one pump (that is, the first pump 51).

In this way, 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 directional switching valve 30 that regulates the supply and discharge of hydraulic oil to the hydraulic cylinder 18 for driving the boom 14 has the configuration shown in FIG. 2, but another directional switching valve 70. , 71, 72 (particularly, the directional switching valves 71, 72 that regulate the supply and discharge of hydraulic oil to 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 added to each element of the above-described embodiment and modification. In addition, a form including a component other than the above-mentioned components is also included in the embodiment of the present invention. In addition, an embodiment of the present invention also includes a form in which some of the above-mentioned components are not included. Therefore, the components included in each of the above-described embodiments and modifications and the embodiments of the present invention other than the above may be combined, and the embodiments related to such combinations are also included in the embodiments of the present invention. .. Further, the effect produced by the present invention is not limited to the above-mentioned effect, and a peculiar effect according to the specific configuration of each embodiment can be exhibited. In this way, various additions, changes and partial deletions can be made to each element described in the claims, the specification, the abstract and the drawings without departing from the technical idea and purpose of the present invention. Is.

For example, the merging passage 45 may 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. Further, the connecting passage 44 may communicate with the other of the first branch passage 48 and the first parallel passage 46. However, even in this case, the connecting passage 44 does not communicate with the merging passage 45.

10 Hydraulic excavator 11 Lower frame 12 Upper frame 13 Swing motor 14 Boom 15 Arm 16 Bucket 17 Traveling motor 18 Hydraulic cylinder 18a 1st port 18b 2nd port 19 Hydraulic cylinder 20 Hydraulic cylinder 30 Direction switching valve 30a Neutral position 30b 1st operating position 30c 2nd operating position 31 Valve body 32 Spool 33 Spool hole 34 1st unload passage 34a Upstream side 1st unload passage 34b Downstream side 1st unload passage 35 2nd unload passage 35a Upstream side 2nd unload passage 35b Downstream side 2nd unload passage 36 1st supply passage 37 2nd supply passage 40 Actuator passage 41 1st actuator passage 42 2nd actuator passage 43 Bridge passage 44 Connecting passage 45 Confluence passage 46 1st parallel passage (2nd passage)
47 Second parallel passage (third passage)
48 1st branch passage (1st passage)
49 2nd branch passage (4th passage)
50 Block 51 1st pump 52 2nd pump 53 1st parallel area 54 2nd parallel area 55 1st tandem area 56 2nd tandem area 58 Tank passage 59 Tank 61 1st check valve 62 2nd check valve 63 3rd check Valve 64 4th check valve 70 Direction switching valve 71 Direction switching valve 72 Direction switching valve

Claims (8)

The valve body with spool holes and
The spool arranged in the spool hole and
A bridge passage that is formed in a bridge shape and opens into the spool hole, and is divided into a merging passage and a connecting 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 are provided.
The first flow path and the second flow path are communicated with the first pump.
The third flow path and the fourth flow path are communicated with the second pump.
When the spool is arranged 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 confluence passage,
A directional switching valve in which at least one of the first flow path and the second flow path is communicated with the connecting passage when the spool is arranged at the second position. The valve body has an actuator passage that opens into the spool hole and communicates with the actuator.
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 communicate with the confluence passage.
The connecting 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 changes the communication state and the cutoff state between the bridge passage and the actuator passage according to the arrangement position in the spool hole.
When the spool is arranged at the first position, the spool cuts off between the connecting passage and the actuator passage while communicating the merging passage with the actuator passage through the spool hole. And
When the spool is arranged at the second position, the spool communicates the connecting passage to the actuator passage through the spool hole while blocking the space between the merging passage and the actuator passage. The direction switching valve according to claim 1. The direction switching valve according to claim 2, wherein the blocking portion closes one end of the merging passage while closing one end of the connecting passage. The actuator passage is arranged closer to the first actuator passage of the merging passage and the connecting passage by the connecting passage, and by the merging passage of the merging passage and the connecting passage. Has 2 actuator passages,
When the spool is arranged at the first position, the spool communicates the confluence passage with the second actuator passage through the spool hole, and connects the connecting passage and the first actuator passage. Cut off between
When the spool is arranged at the second position, the spool cuts between the merging passage and the second actuator passage, and makes the connecting passage through the spool hole to the first. The direction switching valve according to claim 2 or 3, which is communicated with an actuator passage. 2. When the spool is arranged at the third position, the spool cuts off between the connecting passage and the actuator passage while blocking between the merging passage and the actuator passage. The direction switching valve according to any one of the items 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 passage to the third flow path, and the first check valve from the connecting passage. A claim further comprising at least one of a third check valve that prevents backflow of hydraulic oil into one flow path and a fourth check valve that prevents backflow of hydraulic oil from the merging passage to the fourth flow path. 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.

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