JP2020133752A - Construction machine - Google Patents

Abstract

To provide a construction machine capable of preventing a trouble from occurring in another hydraulic device due to dispersion of foreign matter occurring in a hydraulic pump and a hydraulic motor.SOLUTION: A hydraulic excavator comprises revolving hydraulic motors 6A, 6B and a boom hydraulic cylinder 10, hydraulic pumps 16A, 16B for a closed circuit, and switching valves 21A to 21D that selectively connects the revolving hydraulic motors 6A and 6B, the boom hydraulic cylinder 10 and the hydraulic pumps 16A and 16B in a closed circuit form. The hydraulic excavator also comprises two pairs of unidirectional oil filters 25A to 25D provided for ports of the hydraulic pumps 16A and 16B, and two pairs of unidirectional oil filters 26A to 26D provided for the ports of the revolving hydraulic motors 6A and 6B.SELECTED DRAWING: Figure 4

Description

The present invention relates to a construction machine including a hydraulic system using a closed circuit.

In recent years, energy saving has become an important development item in construction machinery such as hydraulic excavators. Energy saving of hydraulic systems is important for energy saving of construction machinery, and application of closed circuits is being considered. In the open circuit, a control valve is provided between the hydraulic pump and the hydraulic actuator, and this control valve controls the flow direction and flow rate of hydraulic oil (pressure oil) to control the operating direction and speed of the hydraulic actuator. .. On the other hand, in the closed circuit, the discharge direction and discharge flow rate of the hydraulic pump are controlled to control the operation direction and speed of the hydraulic actuator. Therefore, there is no pressure loss due to the throttle of the control valve, and there is no flow rate loss because the hydraulic pump discharges only the flow rate required to drive the hydraulic actuator. It is also possible to regenerate the potential energy of the driven member and the energy during deceleration. Therefore, energy saving can be achieved.

Patent Document 1 describes four hydraulic actuators (specifically, a boom hydraulic cylinder, an arm hydraulic cylinder, a bucket hydraulic cylinder, and a turning hydraulic motor) and four for closing circuits in the hydraulic system of a hydraulic excavator. It is disclosed that the hydraulic pumps and 16 switching valves for selectively connecting the hydraulic actuator and the hydraulic pumps described above in a closed circuit form are provided. In this hydraulic system, by selectively connecting the hydraulic actuator and the hydraulic pump in a closed circuit manner, it is possible to perform combined operation and high-speed operation of the hydraulic actuator.

Patent Document 2 discloses that in a closed circuit connecting one hydraulic cylinder and one hydraulic pump, a pair of unidirectional oil filters are provided for each of the ports of the hydraulic pump. Each oil filter has a filter element and two check valves, and when the hydraulic oil flows in from the hydraulic pump and flows out to the hydraulic cylinder, the hydraulic oil passes through the filter element and the hydraulic oil flows into the hydraulic cylinder. It is configured so that the hydraulic oil does not pass through the filter element when it flows in from and flows out to the hydraulic pump.

Japanese Unexamined Patent Publication No. 2015-048899

Japanese Patent No. 3020066

It is conceivable to provide a unidirectional oil filter of Patent Document 2 in order to keep the hydraulic oil clean in the hydraulic system of the hydraulic excavator of Patent Document 1. That is, it is conceivable to provide a plurality of pairs of unidirectional oil filters for the ports of the plurality of hydraulic pumps. In this case, foreign matter such as abrasion powder generated by the wear of the hydraulic pump can be collected by the oil filter. This makes it possible to prevent foreign matter generated by the hydraulic pump from diffusing and causing troubles in other hydraulic devices. Further, even if the discharge direction of the hydraulic pump is changed, it is possible to prevent the foreign matter collected by the oil filter from being discharged and sucked into the hydraulic pump.

By the way, although the hydraulic cylinder does not slide between the metals, the hydraulic motor slides in a state where the metals are in contact with each other with a high load like the hydraulic pump. Therefore, the hydraulic motor, like the hydraulic pump, may generate foreign matter such as abrasion powder. Then, foreign matter generated by the hydraulic motor may diffuse and cause troubles in other hydraulic devices.

The present invention has been made in view of the above matters, and an object of the present invention is to provide a construction machine capable of preventing foreign matter generated by a hydraulic pump and a hydraulic motor from diffusing and causing troubles of other hydraulic equipment. There is.

In order to achieve the above object, the present invention selectively selects a plurality of hydraulic actuators including at least one hydraulic motor, a plurality of hydraulic pumps for closing circuits, the plurality of hydraulic actuators, and the plurality of hydraulic pumps. In a construction machine provided with a plurality of switching valves connected in a closed circuit manner, a plurality of pairs of unidirectional first oil filters provided for the ports of the plurality of hydraulic pumps and the at least one hydraulic motor. It is provided with at least a pair of unidirectional second oil filters provided for the port.

According to the present invention, it is possible to prevent foreign matter generated by the hydraulic pump and the hydraulic motor from diffusing and causing troubles in other hydraulic devices.

It is a side view which shows the structure of the hydraulic excavator in one Embodiment of this invention. It is a top view which shows the equipment layout in the upper swing body in one Embodiment of this invention. It is a perspective view which shows the equipment layout between boom brackets in one Embodiment of this invention. It is a figure which shows a part of the structure of the hydraulic system in one Embodiment of this invention. It is a side view which shows the integrated structure of the turning hydraulic motor and the oil filter in one Embodiment of this invention. It is a side view which shows the integrated structure of the turning hydraulic motor and the oil filter in one Embodiment of this invention. 5 and 6 are cross-sectional views taken along the middle sections VII-VII, showing the structure of the oil filter. It is the schematic for demonstrating the operation of the oil filter in one Embodiment of this invention.

An embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a side view showing the structure of the hydraulic excavator according to the present embodiment. FIG. 2 is a plan view showing the equipment layout in the upper swivel body in the present embodiment. FIG. 3 is a perspective view showing the equipment layout between the boom brackets in the present embodiment. After that, the front side (left side of FIG. 1, left side of FIG. 2), the rear side (right side of FIG. 1, the right side of FIG. 2), and the left side (front of the paper in FIG. 1) of the operator boarding the cab of the hydraulic excavator. The side, the lower side of FIG. 2, and the right side (the back side with respect to the paper surface of FIG. 1, the upper side of FIG. 2) are simply referred to as the front side, the rear side, the left side, and the right side.

The hydraulic excavator of the present embodiment is a large-sized hydraulic excavator having an operating mass of about several hundred tons, and is used for mining, for example, in a mine. This hydraulic excavator is connected to the lower traveling body 2 provided with the crawler type traveling device 1, the upper rotating body 4 provided on the upper side of the lower traveling body 2 via the swivel device 3, and the front side of the upper swivel body 4. It is equipped with a working device 5. The swivel device 3 is driven by swivel hydraulic motors 6A and 6B (see FIG. 2) to swivel the upper swivel body 4 with respect to the lower traveling body 2.

The work device 5 is rotatably connected to a boom 7 rotatably connected to the front portion of the upper swivel body 4 (specifically, boom brackets 50A and 50B of the swivel frame) and a tip portion of the boom 7. The arm 8 and the bucket 9 rotatably connected to the tip of the arm 8 are provided. The boom 7 rotates by expanding and contracting the single-rod type boom hydraulic cylinder 10. The arm 8 rotates due to expansion and contraction of the arm hydraulic cylinder 11. The bucket 9 rotates due to expansion and contraction of the bucket hydraulic cylinder 12.

A cab 13 on which the operator is boarded is provided on the left side of the front portion of the upper swivel body 4. An engine 14 (power source), a power transmission device 15, hydraulic pumps 16A and 16B for closing circuits, and hydraulic pumps 17A and 17B for opening circuits are mounted on the rear portion of the upper swing body 4. The power transmission device 15 is connected between the engine 14 and the hydraulic pumps 16A, 16B, 17A, 17B, and distributes the power of the engine 14 to the hydraulic pumps.

A fuel tank 18, a hydraulic oil tank 19, and a valve unit 20 are mounted in the central portion of the upper swing body 4 in the front-rear direction. The valve unit 20 includes switching valves 21A to 21D, on-off valves 22A and 22B, and bleed-off valves 23A and 23B, as shown in FIG. 4 described later. The swivel hydraulic motors 6A and 6B described above are arranged on the front side of the valve unit 20 (in other words, between the boom brackets 50A and 50B of the swivel frame).

The hydraulic excavator includes a hydraulic system for driving a plurality of hydraulic actuators (specifically, the above-described turning hydraulic motors 6A and 6B, boom hydraulic cylinder 10, arm hydraulic cylinder 11, bucket hydraulic cylinder 12, etc.). ing. Among the configurations of this hydraulic system, the configurations related to the driving of the turning hydraulic motors 6A and 6B and the boom hydraulic cylinder 10 will be described with reference to FIG. FIG. 4 is a diagram showing a part of the configuration of the hydraulic system in the present embodiment.

The hydraulic system of this embodiment includes hydraulic pumps 16A and 16B for closed circuits (specifically, bidirectional discharge type and variable capacitance type), hydraulic pumps 16A and 16B, a boom hydraulic cylinder 10, and a swivel hydraulic motor 6A. It is provided with switching valves 21A to 21D for selectively connecting 6B in a closed circuit manner. The swivel hydraulic motors 6A and 6B are connected in parallel to the switching valves 21B and 21D.

The tilt angle of the swash plate of the hydraulic pump 16A is controlled by a regulator (not shown). As a result, the discharge direction of the hydraulic pump 16A (in other words, which of the pair of ports is used as the discharge port) is controlled, and the discharge amount is controlled. Similarly, the tilt angle of the swash plate of the hydraulic pump 16B is controlled by a regulator (not shown). As a result, the discharge direction of the hydraulic pump 16B is controlled, and the discharge amount is controlled. Each regulator controls the inclination angle of the swash plate of the hydraulic pump in response to a command from a controller (not shown).

The switching valve 21A switches between a cutoff state and a communication state according to a signal from the controller. When no signal from the controller is input, the switching valve 21A is shut off. As a result, the oil passage between one port of the hydraulic pump 16A and the rod side of the boom hydraulic cylinder 10 is cut off, and the oil passage between the other port of the hydraulic pump 16A and the bottom side of the boom hydraulic cylinder 10 To shut off. When a signal from the controller is input, the switching valve 21A is in a communicating state. As a result, the oil passage between one port of the hydraulic pump 16A and the rod side of the boom hydraulic cylinder 10 is communicated, and the oil passage between the other port of the hydraulic pump 16A and the bottom side of the boom hydraulic cylinder 10 Communicate with. Therefore, the hydraulic pump 16A and the boom hydraulic cylinder 10 are connected in a closed circuit manner.

The switching valve 21B switches between a cutoff state and a communication state according to a signal from the controller. When no signal from the controller is input, the switching valve 21B is shut off. As a result, the oil passage between one port of the hydraulic pump 16A and one port of the swivel hydraulic motors 6A and 6B is cut off, and the other port of the hydraulic pump 16A and the other of the swivel hydraulic motors 6A and 6B are blocked. Block the oil passage between the ports. When a signal from the controller is input, the switching valve 21B is in a communicating state. As a result, the oil passage between one port of the hydraulic pump 16A and one port of the swivel hydraulic motors 6A and 6B is communicated, and the other port of the hydraulic pump 16A and the other of the swivel hydraulic motors 6A and 6B are connected. Communicate the oil passage between the ports. Therefore, the hydraulic pump 16A and the turning hydraulic motors 6A and 6B are connected in a closed circuit manner.

The switching valve 21C switches between a cutoff state and a communication state according to a signal from the controller. When no signal from the controller is input, the switching valve 21C is shut off. As a result, the oil passage between one port of the hydraulic pump 16B and the rod side of the boom hydraulic cylinder 10 is cut off, and the oil passage between the other port of the hydraulic pump 16B and the bottom side of the boom hydraulic cylinder 10 To shut off. When a signal from the controller is input, the switching valve 21C is in a communicating state. As a result, the oil passage between one port of the hydraulic pump 16B and the rod side of the boom hydraulic cylinder 10 is communicated, and the oil passage between the other port of the hydraulic pump 16B and the bottom side of the boom hydraulic cylinder 10 Communicate with. Therefore, the hydraulic pump 16B and the boom hydraulic cylinder 10 are connected in a closed circuit manner.

The switching valve 21D switches between a cutoff state and a communication state according to a signal from the controller. When no signal from the controller is input, the switching valve 21D is shut off. As a result, the oil passage between one port of the hydraulic pump 16B and one port of the swivel hydraulic motors 6A and 6B is cut off, and the other port of the hydraulic pump 16B and the other of the swivel hydraulic motors 6A and 6B are blocked. Block the oil passage between the ports. When a signal from the controller is input, the switching valve 21D is in a communicating state. As a result, the oil passage between one port of the hydraulic pump 16B and one port of the swivel hydraulic motors 6A and 6B is communicated, and the other port of the hydraulic pump 16B and the other of the swivel hydraulic motors 6A and 6B are connected. Communicate the oil passage between the ports. Therefore, the hydraulic pump 16B and the turning hydraulic motors 6A and 6B are connected in a closed circuit manner.

The hydraulic system of the present embodiment is between the hydraulic pumps 17A and 17B for open circuits (specifically, one-way discharge type and variable capacitance type) and the discharge port of the hydraulic pump 17A and the bottom side of the boom hydraulic cylinder 10. The on-off valve 22A provided in the oil passage, the bleed-off valve 23A connected to the oil passage between the discharge port of the hydraulic pump 17A and the on-off valve 22A, the discharge port of the hydraulic pump 17B, and the hydraulic cylinder 10 for the boom. An on-off valve 22B provided in the oil passage between the bottom sides and a bleed-off valve 23B connected to the oil passage between the discharge port of the hydraulic pump 17B and the on-off valve 22B are further provided. The on-off valves 22A and 22B and the bleed-off valves 23A and 23B open and close in response to a signal from the controller.

Next, the operations of the boom hydraulic cylinder 10 and the swivel hydraulic motors 6A and 6B of the present embodiment will be described.

When extending the boom hydraulic cylinder 10, for example, the switching valve 21A is in the communicating state, the on-off valve 22A is in the open state, the bleed-off valve 23A is in the closed state, and the other port of the hydraulic pump 16A and the hydraulic pump 17A The hydraulic oil is discharged from the discharge port. As a result, hydraulic oil for two pumps flows into the bottom side of the boom hydraulic cylinder 10, and the boom hydraulic cylinder 10 expands. The hydraulic oil discharged from the rod side of the boom hydraulic cylinder 10 is sucked into one port of the hydraulic pump 16A, but when the flow rate becomes excessive, a charge line is provided via a flushing valve (not shown). It is discharged to (not shown). On the other hand, when the flow rate of the hydraulic oil is insufficient, the hydraulic oil is supplied from the charge line via the flushing valve or the make-up check valve.

By increasing the number of pumps that supply hydraulic oil to the bottom side of the boom hydraulic cylinder 10, high-speed extension operation can be performed. Specifically, for example, the switching valves 21A and 21C are in the communicating state, the on-off valves 22A and 22B are in the open state, the bleed-off valves 23A and 23B are in the closed state, the other port of the hydraulic pump 16A, and the other of the hydraulic pump 16B. The hydraulic oil is discharged from the port, the discharge port of the hydraulic pump 17A, and the discharge port of the hydraulic pump 17B. As a result, it is possible to supply the flow rate of the hydraulic oil for four pumps to the bottom side of the boom hydraulic cylinder 10 to perform a high-speed extension operation.

When the boom hydraulic cylinder 10 is pulled in, for example, the switching valve 21A is in the communicating state, the on-off valve 22A is in the open state, the bleed-off valve 23A is in the open state, and hydraulic oil is discharged from one port of the hydraulic pump 16A. To do. As a result, the hydraulic oil flows into the rod side of the boom hydraulic cylinder 10, and the boom hydraulic cylinder 10 is retracted. The hydraulic oil discharged from the bottom side of the boom hydraulic cylinder 10 is sucked into the other port of the hydraulic pump 16A and discharged to the hydraulic oil tank 19 via the on-off valve 22A and the bleed-off valve 23A.

When the turning hydraulic motors 6A and 6B are rotated, for example, the switching valve 21B is in a communicating state, and hydraulic oil is discharged from one port of the hydraulic pump 16A. As a result, hydraulic oil flows into one port of the turning hydraulic motors 6A and 6B, and the turning hydraulic motors 6A and 6B rotate. The hydraulic oil discharged from the other port of the turning hydraulic motors 6A and 6B is sucked into the other port of the hydraulic pump 16A.

By increasing the number of pumps that supply hydraulic oil to the turning hydraulic motors 6A and 6B, it is possible to perform high-speed extension operation. Specifically, the switching valves 21B and 21D are brought into communication with each other, and hydraulic oil is discharged from one port of the hydraulic pump 16A and one port of the hydraulic pump 16B. As a result, it is possible to supply the flow rates of the hydraulic oil for two pumps to the turning hydraulic motors 6A and 6B to perform high-speed rotation operation. It is also possible to perform a combined operation of the boom hydraulic cylinder 10 and the turning hydraulic motors 6A and 6B.

By the way, the hydraulic pumps 16A, 16B, 17A and 17B slide in a state where the metals are in contact with each other under a high load, and foreign matter such as abrasion powder may be generated. Therefore, ordinary oil filters 24A and 24B are provided for the discharge ports of the hydraulic pumps 17A and 17B for opening the circuit, respectively. One-way type oil filters 25A and 25B (first oil filter) are provided for each pair of ports of the hydraulic pump 16A for closing circuit, and one direction for each pair of ports of the hydraulic pump 16B for closing circuit. Mold oil filters 25C and 25D (first oil filter) are provided, respectively.

Each of the oil filters 25A to 25D has a filter element and two check valves, and when the hydraulic oil flows in from the hydraulic pump and flows out to the switching valve, the hydraulic oil passes through the filter element and is hydraulic oil. The hydraulic oil does not pass through the filter element when the oil flows in from the switching valve and flows out to the hydraulic pump. As a result, foreign matter generated by the hydraulic pump can be collected. Further, even if the discharge direction of the hydraulic pump is changed, it is possible to prevent the foreign matter collected by the oil filter from being discharged and sucked into the hydraulic pump.

Like the hydraulic pumps, the turning hydraulic motors 6A and 6B slide in a state where the metals are in contact with each other under a high load, and foreign matter such as abrasion powder may be generated. Therefore, unidirectional oil filters 26A and 26B (second oil filters) are provided for the pair of ports of the turning hydraulic motor 6A, respectively, and the unidirectional type is provided for the pair of ports of the turning hydraulic motor 6B. Oil filters 26C and 26D (second oil filter) are provided, respectively.

Each of the oil filters 26A to 26D has a filter element and two check valves, and when the hydraulic oil flows in from the hydraulic motor and flows out to the switching valve, the hydraulic oil passes through the filter element and is hydraulic oil. Is configured so that hydraulic oil does not pass through the filter element when it flows in from the switching valve and flows out to the hydraulic motor. As a result, foreign matter generated by the turning hydraulic motor can be collected. Further, even if the rotation direction of the turning hydraulic motor changes, it is possible to prevent the foreign matter collected by the oil filter from being discharged and flowing into the turning hydraulic motor.

The swivel hydraulic motor 6A and the pair of oil filters 26A and 26B are integrated so that no piping is interposed between them. The swivel hydraulic motor 6B and the pair of oil filters 26C and 26D are integrated so that no piping is interposed between them. As a result, the oil passage between the turning hydraulic motor and the switching valve can be shortened, and the pressure loss can be reduced. In addition, the number of pipes can be reduced to improve mountability and maintainability. In particular, since a large number of pipes connected to the boom hydraulic cylinder 10 and the like are arranged between the boom brackets 50A and 50B, the effect is remarkable. Further, as shown in FIGS. 2 and 3 described above, the oil filters 26A and 26B and the oil filters 26C and 26D are arranged so as to face each other. As a result, mountability and maintainability can be improved. The hydraulic excavator of the present embodiment includes two turning hydraulic motors 6A and 6B, but if it is a larger one, it is provided with, for example, six turning hydraulic motors. In this case, the above-mentioned effect becomes remarkable.

Next, the structures of the unidirectional oil filters 26A to 26D of the present embodiment will be described. 5 and 6 are side views showing an integrated structure of the turning hydraulic motor 6A and the oil filters 26A and 26B in the present embodiment. FIG. 7 is a cross-sectional view taken along the middle sections VII-VII of FIGS. 5 and 6, and shows the structures of the oil filters 26A and 26B. The oil filter in FIG. 5 shows a cross-sectional view taken along the cross section VV in FIG. 7, and the oil filter in FIG. 6 shows a cross-sectional view taken along the cross section VI-VI in FIG.

The unidirectional oil filter 26A is a part of the first flow path 33A and the first flow path 33A formed between the port 31A on the hydraulic motor side, the port 32A on the switching valve side, and the ports 31A and 32A. Allows the flow from the port 32A side (switching valve side) to the port 31A side (hydraulic motor side) in the first flow path 33A and the second flow path 34A connected to the first flow path 33A so as to bypass the above. However, the first check valve 35A that blocks the flow from the port 31A side (hydraulic motor side) to the port 32A side (switching valve side) in the first flow path 33A and the port 31A side (hydraulic motor side) in the second flow path 34A. Although the flow from the motor side) to the port 32A side (switching valve side) is allowed, the flow from the port 32A side (switching valve side) to the port 31A side (hydraulic motor side) in the second flow path 34A is blocked. It is composed of two check valves 36A and a filter element 37A arranged in the second flow path 34A.

Similarly, the unidirectional oil filter 26B has a first flow path 33B and a first flow path 33B formed between the port 31B on the hydraulic motor side, the port 32B on the switching valve side, and the ports 31B and 32B. The second flow path 34B connected to the first flow path 33B so as to bypass a part of the flow from the port 32B side (switching valve side) to the port 31B side (hydraulic motor side) in the first flow path 33B. The first check valve 35B that blocks the flow from the port 31B side (hydraulic motor side) to the port 32B side (switching valve side) in the first flow path 33B, and the port 31B in the second flow path 34B. Although the flow from the side (hydraulic motor side) to the port 32B side (switching valve side) is allowed, the flow from the port 32B side (switching valve side) to the port 31B side (hydraulic motor side) in the second flow path 34B is allowed. It is composed of a second check valve 36B for blocking and a filter element 37B arranged in the second flow path 34B.

The configuration of the oil filter 26A and the configuration of the oil filter 26B described above are provided in the same block 38. As a result, the oil filter 26A and the oil filter 26B are integrated. A plurality of screw holes 51 are formed in the turning hydraulic motor 6A, and a plurality of through holes 52 are formed in the block 38 corresponding to the plurality of screw holes 51, respectively. Then, each bolt 53 is inserted into the through hole 52 and screwed into the screw hole 51, whereby the turning hydraulic motor 6A and the block 38 are coupled. As a result, no piping is interposed between one port of the turning hydraulic motor 6A and the port 31A of the oil filter 26A, and between the other port of the turning hydraulic motor 6A and the port 31B of the oil filter 26B. The turning hydraulic motor 6A and the oil filters 26A and 26B are integrated so that the piping does not intervene.

Since the oil filters 26C and 26D have the same structure as the oil filters 26A and 26B, the description thereof will be omitted. As shown in FIGS. 2 to 4 above, pipes 27A to 27D are connected to the switching valve side ports of the oil filters 26A to 26D, respectively. The pipes 27A and 27C are connected to the three-way joint 28A, and the three-way joint 28A is connected to the switching valves 21B and 21D of the valve unit 20 via the pipe 27E. The pipes 27B and 27D are connected to the three-way joint 28B, and the three-way joint 28B is connected to the switching valves 21B and 21D of the valve unit 20 via the pipe 27F. As a result, the turning hydraulic motors 6A and 6B are connected in parallel to the switching valves 21B and 21D.

Next, the operation and action effect of the oil filter of the present embodiment will be described. FIG. 8 is a diagram for explaining the operation of the oil filter in the present embodiment. Note that FIG. 8 shows a closed circuit composed of the hydraulic pump 16A and the turning hydraulic motor 6A as an example, and for convenience, the switching valve 21B, the turning hydraulic motor 6B, and the oil filters 26C and 26D are omitted. The turning hydraulic motor 6A and the oil filters 26A and 26B are shown separately. The thick arrow in FIG. 8 indicates the flow of hydraulic oil from the hydraulic pump 16A to the turning hydraulic motor 6A, and the dotted arrow in FIG. 8 indicates the flow of hydraulic oil from the turning hydraulic motor 6A to the hydraulic pump 16A. It shows the flow.

First, the structures of the oil filters 25A and 25B will be described. The unidirectional oil filter 25A comprises a first flow path 43A formed between the port 41A on the hydraulic pump side, the port 42A on the switching side, the ports 41A and 42A, and a part of the first flow path 43A. Although the second flow path 44A connected to the first flow path 43A so as to bypass and the flow from the port 41A side (hydraulic pump side) to the port 42A side (switching valve side) in the first flow path 43A are allowed. , The first check valve 45A that blocks the flow from the port 42A side (switching valve side) to the port 41A side (hydraulic pump side) in the first flow path 43A, and the port 42A side (switching valve) in the second flow path 44A. A second that allows flow from the side) to the port 41A side (hydraulic pump side), but blocks the flow from the port 41A side (hydraulic pump side) to the port 42A side (switching valve side) in the second flow path 44A. It is composed of a check valve 46A and a filter element 47A arranged in the first flow path 43A.

Similarly, the one-way type oil filter 25B has a first flow path 43B and a first flow path 43B formed between the port 41B on the hydraulic pump side, the port 42B on the switching side, and the ports 41B and 42B. The flow from the port 41B side (hydraulic pump side) to the port 42B side (switching valve side) in the first flow path 43B and the second flow path 44B connected to the first flow path 43B so as to bypass a part of the flow. The first check valve 45B that blocks the flow from the port 42B side (switching valve side) to the port 41B side (hydraulic pump side) in the first flow path 43B and the port 42B side in the second flow path 44B, although they are allowed. Allows the flow from the (switching valve side) to the port 41B side (hydraulic pump side), but blocks the flow from the port 41B side (hydraulic pump side) to the port 42B side (switching valve side) in the second flow path 44B. It is composed of a second check valve 46B and a filter element 47B arranged in the first flow path 43B.

The hydraulic oil discharged from one port of the hydraulic pump 16A flows into the port 41A of the oil filter 25A and pushes open the valve body of the first check valve 45A (however, the closed state is shown in FIG. 8). As a result, the hydraulic oil flows out from the port 42A via the filter element 47A of the oil filter 25A. After that, the hydraulic oil flows into the port 32A of the oil filter 26A via a switching valve 21B (not shown) and pushes open the valve body of the first check valve 35A (however, the closed state is shown in FIG. 8). As a result, the hydraulic oil flows out from the port 31A without passing through the filter element 37A of the oil filter 26A. After that, the hydraulic oil flows into one port of the turning hydraulic motor 6A. As a result, the turning hydraulic motor 6A rotates, and the turning operation of the hydraulic excavator is performed.

The hydraulic oil discharged from the other port of the turning hydraulic motor 6A flows into the port 31B of the oil filter 26B and pushes open the valve body of the second check valve 36B (however, FIG. 8 shows a closed state. ). As a result, the hydraulic oil flows out from the port 32B via the filter element 37B of the oil filter 26B. After that, the hydraulic oil flows into the port 42B of the oil filter 25B via a switching valve 21B (not shown) and pushes open the valve body of the second check valve 46B (however, the closed state is shown in FIG. 8). As a result, the hydraulic oil flows out from the port 41B without passing through the filter element 47B of the oil filter 25B. The hydraulic oil is then sucked into the other port of the hydraulic pump 16A.

As described above, when the hydraulic oil is discharged from one port of the hydraulic pump 16A, in the oil filter 25A, the hydraulic oil from the hydraulic pump 16A passes through the filter element 47A. As a result, the foreign matter generated by the hydraulic pump 16A can be collected by the filter element 47A. Alternatively, when the hydraulic oil is discharged from the other port of the hydraulic pump 16A, in the oil filter 25B, the hydraulic oil from the hydraulic pump 16A passes through the filter element 47B. As a result, the foreign matter generated by the hydraulic pump 16A can be collected by the filter element 47B. As a result, it is possible to prevent the foreign matter generated by the hydraulic pump 16A from diffusing and causing troubles in other hydraulic devices. As a specific example, it is possible to prevent sticking of the switching valve 21B and damage to the turning hydraulic motors 6A and 6B due to foreign matter generated in the hydraulic pump 16A. Further, assuming that the switching valve 21A is in a communicating state, it is possible to prevent the switching valve 21A from sticking due to foreign matter generated by the hydraulic pump 16A and the boom hydraulic cylinder 10 from being damaged. The oil filters 25C and 25D also have the same effect as the oil filters 25A and 25B.

As described above, when the hydraulic oil is discharged from the other port of the turning hydraulic motor 6A, in the oil filter 26B, the hydraulic oil from the turning hydraulic motor 6A passes through the filter element 37B. As a result, foreign matter generated by the turning hydraulic motor 6A can be collected by the filter element 37B. Alternatively, when the hydraulic oil is discharged from one port of the turning hydraulic motor 6A, in the oil filter 26A, the hydraulic oil from the turning hydraulic motor 6A passes through the filter element 37A. As a result, foreign matter generated by the turning hydraulic motor 6A can be collected by the filter element 37A. As a result, it is possible to prevent the foreign matter generated by the turning hydraulic motor 6A from diffusing and causing troubles in other hydraulic devices. As a specific example, it is possible to prevent the switching valve 21B from sticking and the hydraulic pump 16A from being damaged by foreign matter generated by the turning hydraulic motor 6A. Further, assuming that the switching valve 21D is in a communicating state, it is possible to prevent the switching valve 21D from sticking and the hydraulic pump 16B from being damaged by foreign matter generated by the turning hydraulic motor 6A. The oil filters 26C and 26D also have the same effect as the oil filters 26A and 26B.

Therefore, in the present embodiment, it is possible to prevent the foreign matter generated in the hydraulic pump and the hydraulic motor from diffusing and causing troubles in other hydraulic devices. As a result, the durability and reliability of the hydraulic excavator can be improved. In addition, the downtime of the hydraulic excavator can be reduced.

In the above embodiment, the combination of one hydraulic motor and a pair of unidirectional oil filters has been described by taking as an example a case where they are connected by using bolts or the like and integrated, but the present invention is not limited to this. , Modification is possible within a range that does not deviate from the gist of the present invention. That is, the combination of one hydraulic motor and a pair of unidirectional oil filters may be integrated by providing their configurations in the same block. Further, although the effect cannot be obtained, the combination of one hydraulic motor and a pair of unidirectional oil filters does not have to be integrated.

Further, in the above embodiment, the hydraulic excavator includes a plurality of swivel hydraulic motors and a plurality of pairs of unidirectional oil filters provided for each of the ports of the swivel hydraulic motors. However, the present invention is not limited to this, and modifications can be made without departing from the spirit of the present invention. That is, the hydraulic excavator may include only one swivel hydraulic motor and a pair of only one-way oil filters provided for each port of the swivel hydraulic motor. In this case as well, the same effect as described above can be obtained.

Further, in the above embodiment, the combination of one hydraulic pump and a pair of unidirectional oil filters has been described as an example when they are not integrated, but the present invention is not limited to this, and the combination does not deviate from the gist of the present invention. Can be transformed with. That is, the combination of one hydraulic pump and a pair of unidirectional oil filters may be integrated.

In the above, the hydraulic excavator has been described as an example of application of the present invention, but the present invention is not limited to this, and other construction machines such as a hydraulic crane may be used.

6A, 6B Hydraulic motor for turning 10 Hydraulic cylinder for boom 16A, 16B Hydraulic pump for closed circuit 21A to 21D Switching valve 25A to 25D One-way oil filter (first oil filter)
26A-26D One-way oil filter (second oil filter)

Claims (3)

A plurality of hydraulic actuators including at least one hydraulic motor, a plurality of hydraulic pumps for closing circuits, and a plurality of switching valves for selectively connecting the plurality of hydraulic actuators and the plurality of hydraulic pumps in a closed circuit manner. In the construction machinery equipped
A plurality of pairs of unidirectional first oil filters provided for the ports of the plurality of hydraulic pumps,
A construction machine comprising at least a pair of unidirectional second oil filters provided for the ports of at least one hydraulic motor. In the construction machine according to claim 1,
The plurality of hydraulic actuators include a plurality of hydraulic motors.
The plurality of hydraulic motors are connected in parallel to the switching valve.
A construction machine characterized in that the second oil filter is provided for each of the ports of the plurality of hydraulic motors and has a plurality of pairs. In the construction machine according to claim 2.
A construction machine characterized in that a combination of one hydraulic motor and a pair of second oil filters is integrated so that no piping is interposed between them.

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