HYDRAULIC VALVE APPARATUS

A hydraulic valve apparatus that is interposed between a hydraulic device and a hydraulic pump and controls supply of oil from the hydraulic pump to the hydraulic device by operating a spool provided in a valve body. Further, the valve body includes traveling spools separately provided for two traveling hydraulic devices, working equipment spools provided corresponding to working equipment hydraulic devices, and two pump oil passages connected to the hydraulic pump via pump ports, and the two traveling spools are separately connected to the pump oil passages at positions at which distances from the pump ports are equal to each other without passing through other spools.

FIELD

The present invention relates to a hydraulic valve apparatus, and specifically relates to a hydraulic valve apparatus including a traveling spool provided corresponding to a traveling hydraulic device and a working equipment spool provided corresponding to a working equipment hydraulic device.

BACKGROUND

For example, in a work machine, a hydraulic motor which is a traveling hydraulic device and a hydraulic cylinder which is working equipment hydraulic device are provided, and desired work is performed by appropriately operating the hydraulic devices. A hydraulic valve apparatus that controls supply of oil from a hydraulic pump serving as an oil supply source to the hydraulic devices is provided between each hydraulic device and the hydraulic pump. That is, the hydraulic valve apparatus includes spools separately provided in the valve body corresponding to the respective hydraulic devices, and can control the supply of oil to the hydraulic devices by operating the spools (for example, refer to Patent Literature 1).

CITATION LIST

Patent Literature

SUMMARY

Technical Problem

In a general work machine, traveling devices such as crawler belts are provided on left and right sides of a vehicle body, and two hydraulic motors for driving such traveling devices are also provided. Therefore, by independently driving the left and right traveling devices, it is possible to travel along a desired track in addition to forward movement and backward movement by appropriately changing a traveling direction of the work machine. However, in the above-mentioned hydraulic valve apparatus, even when the two traveling spools are operated so that supply flow rates of oil to the left and right hydraulic motors are the same, a difference in actual pressure and flow rate of oil supplied to the hydraulic motors can occur, which can cause the work machine to not move in a straight line.

In view of the above circumstances, an object of the present invention is to provide a hydraulic valve apparatus that can improve straightness when applied to a work machine including two traveling hydraulic devices.

Solution to Problem

To attain the above object, according to the present invention, a hydraulic valve apparatus is interposed between a hydraulic device and a hydraulic pump and controls supply of oil from the hydraulic pump to the hydraulic device by operating a spool provided in a valve body, in which the valve body includes, traveling spools separately provided for two traveling hydraulic devices, working equipment spools provided corresponding to working equipment hydraulic devices, and two pump oil passages connected to the hydraulic pump via pump ports, and the two traveling spools are separately connected to the pump oil passages at positions at which distances from the pump ports are equal to each other without passing through other spools.

Advantageous Effects of Invention

According to the present invention, since the distances from the pump port to the two traveling spools are the same, there is no problem caused by a difference in a passage length of oil. In addition, since no other spools are interposed therebetween, there is no problem caused by a difference in pressure loss. As a result, by operating the traveling spools so that the supply flow rates of oil are the same for the two traveling hydraulic devices, it is possible to actually equalize a supply pressure and a supply flow rate of oil for the two traveling hydraulic devices, and improve straightness of the work machine to which the invention is applied.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a preferred embodiment of a hydraulic valve apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

FIGS. 1 to 5B conceptually illustrate a hydraulic valve apparatus according to the embodiment of the present invention. As illustrated in FIGS. 6A, 6B, 6C, and 7, a hydraulic valve apparatus 1 exemplified herein is applied to a work machine including an upper swing body 3, a boom 4, and an arm 5 in an upper portion of a lower traveling body 2. The lower traveling body 2 includes crawler belts 6 on both sides and traveling hydraulic motors (traveling hydraulic devices) 7 separately corresponding to respective crawler belts 6, and can travel by driving the crawler belts 6 via the traveling hydraulic motors 7. The upper swing body 3 is rotatably supported around a swing axis along a vertical direction with respect to the lower traveling body 2. A swing hydraulic motor 8 is provided between the lower traveling body 2 and the upper swing body 3 so that the upper swing body 3 can be swung with respect to the lower traveling body 2. The traveling hydraulic motor 7 and the swing hydraulic motor 8 each include two supply ports 7a and 8a, and can rotate in both forward and reverse directions by changing an oil supply direction. A hydraulic pump 9 is mounted on the upper swing body 3. The hydraulic pump 9 is driven by an engine 10, and two hydraulic pumps 9 having the same maximum discharge flow rate are prepared in the upper swing body 3. In the illustrated example, the engine 10 is mounted on the left side in the rear portion of the upper swing body 3, and the two hydraulic pumps 9 are mounted on the right side in the rear portion of the upper swing body 3 while being adjacent to the engine 10. The boom 4 is rotatably supported by the upper swing body 3 via a base end portion by a support shaft along a horizontal direction. The arm 5 is rotatably supported at a distal end portion of the boom 4 via a base end portion thereof by a horizontal support shaft. A boom hydraulic cylinder (working equipment hydraulic device) 11 is provided between the upper swing body 3 and the boom 4, and an arm hydraulic cylinder (working equipment hydraulic device) 12 is provided between the boom 4 and the arm 5. Each of the boom hydraulic cylinder 11 and the arm hydraulic cylinder 12 is a single-rod double-acting type including a single piston rod. The boom hydraulic cylinder 11 is supported by the upper swing body 3 via a cylinder body 11a, and is supported by the boom 4 via a piston rod 11b. The arm hydraulic cylinder 12 is supported by the boom 4 via a cylinder body 12a, and is supported by the arm 5 via a piston rod 12b.

The hydraulic valve apparatus 1 is interposed between the traveling hydraulic motor 7, the swing hydraulic motor 8, the boom hydraulic cylinder 11, and the arm hydraulic cylinder 12 described above (hereinafter, the devices may be collectively referred to as hydraulic devices) and the hydraulic pump 9, controls the supply of oil from the hydraulic pump 9 to the hydraulic devices 7, 8, 11, and 12, and includes a valve body 20 as illustrated in FIG. 1. The valve body 20 is formed in a rectangular parallelepiped shape that is vertically long along the vertical direction in FIG. 1. In the following description, for convenience, in FIG. 1, a surface located obliquely on the right front of the valve body 20 is referred to as a front surface 20a, a surface parallel to the front surface 20a is referred to as a rear surface 20b, and two surfaces located on both sides are referred to as side surfaces 20c and 20d. In addition, in FIG. 1, a surface located upward is referred to as an upper surface 20e, and a surface located downward is referred to as a lower surface 20f.

As illustrated in FIGS. 1 to 5B and FIGS. 8 to 17, two pump oil passages 21A and 21B are provided in the valve body 20. The pump oil passages 21A and 21B extend linearly along the vertical direction of the valve body 20, respectively, and are formed to have the same inner diameter with each other. In the illustrated example, the two pump oil passages 21A and 21B are arranged side by side at symmetrical positions while being parallel to each other in a portion biased toward the rear surface 20b side. Although not clearly illustrated in the drawing, lower ends of the two pump oil passages 21A and 21B are both closed. When closing the lower ends of the pump oil passages 21A and 21B, a plug may be attached after the oil passage is once formed. Upper ends of the two pump oil passages 21A and 21B are opened to the upper surface 20e of the valve body 20. In the present embodiment, the pump oil passages 21A and 21B are connected to the individual hydraulic pumps 9 via pump ports 22A and 22B, respectively. The pump ports 22A and 22B linearly extend rearward from the pump oil passages 21A and 21B, and open on the rear surface 20b of the valve body 20. Although not clearly illustrated in the drawing, distances from the pump ports 22A and 22B to the hydraulic pump 9 are equal to each other.

In each of the pump oil passages 21A and 21B, two cylinder spool holes 23 are provided in each of the upper and lower sides at a portion located above a connection portion with the pump ports 22A and 22B. Further, each of the pump oil passages 21A and 21B is provided with a traveling spool hole 24 at a portion located below the connection portion with the pump ports 22A and 22B. Furthermore, in the pump oil passage 21A disposed on the left side when viewed from the front surface 20a of the valve body 20, one swing spool hole 25 is provided in a portion located below the traveling spool hole 24. The cylinder spool hole 23, the traveling spool hole 24, and the swing spool hole 25 linearly extend along the front-rear direction of the valve body 20, and communicate with the pump oil passages 21A and 21B by penetrating the corresponding pump oil passages 21A and 21B. Both ends of each of the spool holes 23, 24, and 25 are closed.

The cylinder spool hole 23 is provided with a cylinder port 23a at a portion close to the front surface 20a side of the valve body 20. The cylinder port 23a extends from a side portion facing the side surfaces 20c and 20d of the valve body 20 in each cylinder spool hole 23 toward the side surfaces 20c and 20d, respectively, bends toward the front surface 20a side, and is opened to the front surface 20a of the valve body 20. A boom rod oil passage 11Ha communicating with a rod chamber 11H of the boom hydraulic cylinder 11 is connected to the cylinder port 23a that opens to the upper right when viewed from the front surface 20a of the valve body 20. A boom bottom oil passage 11Ba that communicates with a bottom chamber 11B of the boom hydraulic cylinder 11 is connected to the cylinder port 23a that opens to the lower right when viewed from the front surface 20a of the valve body 20. Similarly, an arm bottom oil passage 12Ba that communicates with a bottom chamber 12B of the arm hydraulic cylinder 12 is connected to the cylinder port 23a that opens to the upper left when viewed from the front surface 20a of the valve body 20. An arm rod oil passage 12Ha that communicates with a rod chamber 12H of the arm hydraulic cylinder 12 is connected to the cylinder port 23a that opens to the lower left when viewed from the front surface 20a of the valve body 20.

The traveling spool hole 24 is provided with traveling motor ports 24a1 and 24a2 midway and at a portion adjacent to the front surface 20a side of the valve body 20, respectively. The traveling motor port 24a1 provided midway of the traveling spool hole 24 extends from an upper part facing the upper surface 20e of the valve body 20 toward the upper surface 20e, bends toward the front surface 20a side, and opens to the front surface 20a of the valve body 20. The traveling motor port 24a2 provided in a portion adjacent to the front surface 20a of the valve body 20 extends from lateral portions facing the side surfaces 20c and 20d of the valve body 20 toward the side surfaces 20c and 20d, bends toward the front surface 20a side, and opens to the front surface 20a of the valve body 20. The two traveling motor ports 24a1 and 24a2 that open to the left when viewed from the front surface 20a of the valve body 20 are connected to traveling hydraulic motor oil passages 24MA1 and 24MA2 that communicate with the supply port 7a of the traveling hydraulic motor 7 disposed on the right side of the lower traveling body 2, respectively. The two traveling motor ports 24a1 and 24a2 that open to the right when viewed from the front surface 20a of the valve body 20 are connected to traveling hydraulic motor oil passages 24MB1 and 24MB2 that communicate with the supply port 7a of the traveling hydraulic motor 7 disposed on the left side of the lower traveling body 2, respectively. The left and right sides of each of the traveling hydraulic motors 7 have the same oil supply condition. That is, a passage length of the traveling hydraulic motor oil passages 24MA1+24MA2 connected to one traveling hydraulic motor 7 is equal to a passage length of the traveling hydraulic motor oil passages 24MB1+24MB2 connected to the other traveling hydraulic motor 7, and the inner diameters of the traveling hydraulic motor oil passages 24MA1, 24MA2, 24MB1, and 24MB2 are also equal to each other.

The swing spool hole 25 is provided with swing motor ports 25a1 and 25a2 midway and at a portion adjacent to the front surface 20a side of the valve body 20, respectively. The swing motor port 25a1 provided midway of the swing spool hole 25 extends from a lateral portion facing the right side surface 20d when viewed from the front surface 20a of the valve body 20 toward the side surface 20d, bends toward the front surface 20a side, and opens to the front surface 20a of the valve body 20. The swing motor port 25a2 provided in a portion adjacent to the front surface 20a of the valve body 20 extends from a lateral portion facing the left side surface 20c when viewed from the front surface 20a of the valve body 20 toward the side surface 20c, bends toward the front surface 20a side of the valve body 20, and opens to the front surface 20a of the valve body 20. The two swing motor ports 25a1 and 25a2 are respectively connected to a swing hydraulic motor oil passage 25M communicating with the supply port 8a of the swing hydraulic motor 8.

Spools are separately disposed in the cylinder spool hole 23, the traveling spool hole 24, and the swing spool hole 25 described above. Although not illustrated in the drawings, the spool moves along an axial direction when a pilot pressure is applied from an individual EPC valve (electromagnetic proportional control valve). More specifically, a cylinder spool (working equipment spool) 33 disposed in the cylinder spool hole 23 moves along the axial direction to switch an intermittent state between the pump oil passages 21A and 21B and the cylinder port 23a, and configures a cylinder direction switching valve 33V with the cylinder spool hole 23. Similarly, a traveling spool 34 disposed in the traveling spool hole 24 moves along the axial direction to switch an intermittent state between the pump oil passages 21A and 21B and the traveling motor ports 24a1 and 24a2, and configures a traveling direction switching valve 34V with the traveling spool hole 24. A swing spool 35 disposed in the swing spool hole 25 moves along the axial direction to switch an intermittent state between the pump oil passage 21A and the swing motor ports 25a1 and 25a2, and configures a swing direction switching valve 35V with the swing spool hole 25. Although not clearly illustrated in the drawing, the plurality of EPC valves corresponding to the spools 33, 34, and 35, respectively, are housed in a housing box EPCB provided on the rear surface 20b of the valve body 20.

A unit block 41 of a merging-separating switching unit 40 is disposed on the upper surface 20e of the valve body 20. The unit block 41 has a size capable of simultaneously covering the openings of the two pump oil passages 21A and 21B opened in the upper surface 20e of the valve body 20, and includes a merging-separating oil passage 42 and a valve spool hole 43 therein. The merging-separating oil passage 42 extends in the left-right direction inside the unit block 41, and then each end portion thereof is bent downward and opened to a lower surface of the unit block 41. The merging-separating oil passage 42 is connected to upper ends of the pump oil passages 21A and 21B via lower end openings. The valve spool hole 43 linearly extends along the front-rear direction, and communicates with the merging-separating oil passage 42 by penetrating midway of a portion extending in the left-right direction in the merging-separating oil passage 42. Both end portions of the valve spool hole 43 are closed. A merging-separating spool 44 is disposed in the valve spool hole 43. When the pilot pressure is applied from the EPC valve, the merging-separating spool 44 moves along the axial direction to switch an intermittent state of the merging-separating oil passage 42, and configures a merging-separating switching valve 44V with the valve spool hole 43.

The hydraulic valve apparatus 1 described above is mounted at a position in front of the engine 10 and substantially at the center in the left-right direction in the upper swing body 3 while the front surface 20a of the valve body 20 faces the front of the work machine and the upper surface 20e is upward. In the work machine including the hydraulic valve apparatus 1, when an operation lever (not illustrated) is operated, the corresponding spools 33, 34, 35, and 44 appropriately operate via the EPC valve, and the supply state of oil from the hydraulic pump 9 to the hydraulic devices 7, 8, 11, and 12 is changed. For example, when the pump oil passage 21B and the cylinder port 23a communicate with each other by the operation of the cylinder spool 33 disposed in the upper right portion as viewed from the front surface 20a of the valve body 20, oil from the hydraulic pump 9 is supplied to the rod chamber 11H of the boom hydraulic cylinder 11 via the pump oil passage 21B, the cylinder port 23a, and the boom rod oil passage 11Ha. As a result, the boom hydraulic cylinder 11 is retracted, and it is possible to cause the work machine to perform an operation of moving a distal end of the boom 4 downward. Similarly, when the pump oil passage 21A and the cylinder port 23a communicate with each other by the operation of the cylinder spool 33 disposed in the upper left portion as viewed from the front surface 20a of the valve body 20, oil from the hydraulic pump 9 is supplied to the bottom chamber 12B of the arm hydraulic cylinder 12 via the pump oil passage 21A, the cylinder port 23a, and the arm bottom oil passage 12Ba. As a result, the arm hydraulic cylinder 12 is extended, making it possible to perform an operation for pulling a distal end of the arm 5 toward the upper swing body 3 with respect to the working equipment.

Here, while the merging-separating oil passage 42 is blocked by the merging-separating spool 44, oil is supplied to the hydraulic cylinders 11 and 12 through one of the pump oil passages 21A and 21B. On the other hand, when the merging-separating oil passage 42 is brought into a communicating state by the merging-separating spool 44, oil supplied from one hydraulic pump 9 to one pump oil passage 21A and oil supplied from the other hydraulic pump 9 to the other pump oil passage 21B in the valve body 20 can be merged. As a result, oil can also be supplied from the other pump oil passage 21B to the cylinder port 23a connected to the one pump oil passage 21A, and the operations of the hydraulic cylinders 11 and 12 can be sped up. Moreover, according to the hydraulic valve apparatus 1 described above, the merging-separating switching valve 44V configured by the merging-separating spool 44 is provided in the merging-separating oil passage 42 connecting the upper end portion of each of the pump oil passages 21A and 21B, and the cylinder spool 33 is connected to a portion of each of the pump oil passages 21A and 21B located above connection portions with the pump ports 22A and 22B. Therefore, oil that passed through the merging-separating switching valve 44V does not pass through the traveling spool 34 or the swing spool 35 disposed below the connection portion with the pump ports 22A and 22B before reaching the target cylinder spool 33. Furthermore, since oil that passed through the merging-separating switching valve 44V does not merge with oil supplied from the other hydraulic pump 9 before reaching the target cylinder spool 33, it is possible to prevent pressure loss in the oil passage. As a result, more oil can be efficiently supplied to the target cylinder spool 33 while pressure loss is minimized.

On the other hand, when the operation lever is operated to supply oil to the traveling hydraulic motor 7, the work machine can travel via the crawler belt 6, and when oil is supplied to the swing hydraulic motor 8, the upper swing body 3 can be swung with respect to the lower traveling body 2. According to the above-mentioned hydraulic valve apparatus 1, each of the pump oil passages 21A and 21B is provided with the traveling spool 34 at a portion located below the connection portion with the pump ports 22A and 22B. The passages of oil from the pump ports 22A and 22B to each traveling spool 34 are the same. In addition, the traveling spool 34 is first connected to any portion located below the pump ports 22A and 22B, and the other spools 33 and 35 are not interposed. That is, according to the hydraulic valve apparatus 1 described above, no problem is caused by the difference in the passage length of oil with respect to the two traveling spools 34, and no problem is caused by a difference in pressure loss. As a result, by operating the operation lever for straight travel, supply pressure and supply flow rate of oil to the two traveling spools 34 can be made equal, making it possible to improve the straightness of the work machine to which the invention is applied.

In the embodiment described above, four cylinder spools 33 provided corresponding to the boom 4 and the arm 5 of the work machine are exemplified as working equipment spools, but other working equipment spools may be provided to configure the hydraulic valve apparatus. For example, in the work machine described above, a hydraulic valve apparatus provided with a bucket spool corresponding to a bucket hydraulic cylinder for operating a bucket 13 provided at a distal end portion of the arm 5 may be configured.

In the embodiment described above, the working equipment spool (cylinder spool 33) is provided in the upper portion of the pump oil passages 21A and 21B that is one side with respect to the connection portions with the pump ports 22A and 22B and the traveling spool 34 is provided in the lower portion that is the other side with respect to the connection portions with the pump ports 22A and 22B, but the present invention is not limited thereto. That is, as long as the two traveling spools 34 are respective connected to the pump oil passages 21A and 21B without passing through the other spools 33 and 35 at the positions where the distances from the pump ports 22A and 22B are equal to each other, the two traveling spools 34 may be provided above the connection portions with the pump ports 22A and 22B, or one traveling spool 34 may be provided above the connection portion with the pump port and the other traveling spool 34 may be provided below the connection portion with the pump port. Although the hydraulic pumps 9 are separately connected corresponding to the pump oil passages 21A and 21B, oil from a single hydraulic pump may be supplied to the pump oil passages.

Further, in the above-described embodiment, the two pump oil passages 21A and 21B are connected to each other via the merging-separating oil passage 42 including the merging-separating switching valve 44V, but the present invention does not necessarily include the merging-separating oil passage 42.

REFERENCE SIGNS LIST