Patent Application
20250129572
The present disclosure relates to a construction machine such as a hydraulic excavator, and more particularly, to a construction machine with a closed circuit system performing closed circuit connection between a hydraulic pump and a hydraulic actuator.
Typically, a hydraulic excavator serving as a representative type of construction machine is configured to operate a hydraulic actuator by driving a hydraulic pump with a prime mover and supplying hydraulic oil discharged from the hydraulic pump (pressurized oil) to the hydraulic actuator.
Associated known systems operating a hydraulic actuator with hydraulic oil discharged from a hydraulic pump include closed circuit systems and open circuit systems. A closed circuit system is composed of a closed-circuit hydraulic pump driven by a prime mover and a plurality of closed-circuit pipes connecting the closed-circuit hydraulic pump and a hydraulic actuator. An open circuit system is composed of an open-circuit hydraulic pump driven by a prime mover and a plurality of open-circuit pipes connecting the open-circuit hydraulic pump and a plurality of closed-circuit pipes (Patent Document 1).
In fact, a closed circuit system requires two closed-circuit pipes circulating hydraulic oil between a hydraulic pump and a hydraulic actuator. Specifically, for example, the operation of four hydraulic actuators of a hydraulic excavator: a boom cylinder, an arm cylinder, a bucket cylinder, and a revolving motor in a closed circuit system needs at least four closed-circuit hydraulic pumps and eight closed-circuit pipes. In addition, as disclosed in Patent Document 1, a plurality of open-circuit pipes for operating a traveling hydraulic motor is required even in a case where a drive system of a traveling device is configured by an open circuit pump.
Therefore, numerous hydraulic pipes are disposed between a plurality of hydraulic pumps and a control valve device controlling a plurality of hydraulic actuators. Unfortunately, such numerous hydraulic pipes extending between a plurality of hydraulic pumps and a control valve device are an obstacle to maintenance of the hydraulic pumps or the control valve device, failing to secure a working space and resulting in low operational efficiencies for maintenance and other operations.
In view of the above-described problems of conventional technologies, an object of the present invention is to provide a construction machine capable of securing a working space and improving the operational efficiency by simplifying the arrangement of a closed-circuit pipe group and an open-circuit pipe group.
A construction machine according to the present invention includes: a vehicle body frame; a working mechanism provided on the vehicle body frame; a prime mover provided on the vehicle body frame; a housing with an upper structure covering the prime mover from above; a hydraulic actuator driving the working mechanism; a closed circuit system including a closed-circuit hydraulic pump driven by the prime mover and a closed-circuit pipe group composed of a plurality of closed-circuit pipes connecting the closed-circuit hydraulic pump and the hydraulic actuator; and an open circuit system including an open-circuit hydraulic pump driven by the prime mover and an open-circuit pipe group composed of a plurality of open-circuit pipes connecting the open-circuit hydraulic pump and the plurality of closed-circuit pipes, characterized in that one pipe group of the closed-circuit pipe group and the open-circuit pipe group is distributed through upper positions of the closed-circuit hydraulic pump and the open-circuit hydraulic pump along the upper structure, and the other pipe group is distributed through lower positions of the closed-circuit hydraulic pump and the open-circuit hydraulic pump along the vehicle body frame.
According to the present invention, the arrangement of a closed-circuit pipe group and an open-circuit pipe group can be simplified to secure a working space and improve the operational efficiency.
A representative type of construction machine according to an embodiment of the present invention, by taking the case of a hydraulic excavator, will be explained in detail with reference to
In
The lower traveling structure 2 is configured to include a truck frame 2A, a drive wheel 2B provided on either right or left side of the truck frame 2A, an idler wheel 2C provided on either right or left side of the truck frame 2A and opposite the drive wheel 2B in the front-rear direction, and a crawler belt 2D looped around the drive wheel 2B and the idler wheel 2C (each shown only on the right side). The left drive wheel is rotatively driven by a left traveling hydraulic motor 3 (see
Meanwhile, the upper revolving structure 5 is mounted rotatably on the lower traveling structure 2 through a revolving device 6 (see
The upper revolving structure 5 is configured to include a revolving frame 8 as a vehicle body frame constituting a support structure and including a working mechanism 12 mounted on a front side thereof, a cab 9 mounted on a left front side of the revolving frame 8 and forming an operator's room therein, a housing 20 accommodating a later-described engine 19, a closed-circuit hydraulic pump 29, an open-circuit hydraulic pump 35 and the like (see
Herein, an operator's seat for an on-board operator to be seated (not shown) is provided inside the cab 9. An operating device 11 operating the hydraulic excavator 1 (see
The operating device 11 is connected to a later-described controller 41 via signal lines and the like. An operator can operate the operating device 11 to revolve the upper revolving structure 5, rotate the working mechanism 12 and allow the lower traveling structure 2 to travel. For example, the operator can operate the left control lever 11A to expand and contract an arm cylinder 17 and rotate a later-described arm 14. Also, the operator can operate the right control lever 11B to expand and contract a boom cylinder 16 and rotate a later-described boom 13.
As shown in
The boom cylinder 16, the arm cylinder 17, and the bucket cylinder 18, each as a hydraulic actuator, expand or contract based upon hydraulic oil (pressurized oil) from a later-described closed-circuit hydraulic pump 29 and an open-circuit hydraulic pump 35 to change the posture of the working mechanism 12. That is, the boom cylinder 16, the arm cylinder 17, and the bucket cylinder 18 expand or contract based upon the operation of the left control lever 11A and the right control lever 11B, for example, to rotate the boom 13, the arm 14, and the bucket 15, when the vehicle excavates earth and sand. The resulting operation of the bucket 15 can excavate earth and sand.
Herein, the boom cylinder 16, the arm cylinder 17, and the bucket cylinder 18 are configured as a single rod-type hydraulic cylinder to expand or contract based upon the supply and discharge of hydraulic oil. That is, the boom cylinder 16, the arm cylinder 17, and the bucket cylinder 18 are configured by a tube, a piston slidably inserted into the tube and defining the inside of the tube for a bottom side oil chamber and a rod side oil chamber, and a rod whose base end side is mounted on the piston and whose tip end side projects out of the tube.
As shown in
The prime mover may be a single electric motor, or a hybrid type prime mover composed of a diesel engine and an electric motor combined. Meanwhile, the prime mover may be configured to be longitudinally provided to extend in the front-rear direction of the upper revolving structure 5, or such two prime movers may be disposed in parallel in the right-and-left direction.
The housing 20 is provided on the revolving frame 8 so as to cover apparatuses including the engine 19, the closed-circuit hydraulic pumps 29, the open-circuit hydraulic pumps 35 and the heat exchanger. The housing 20 is configured to include a left side plate (not shown), a right side plate 21 and an upper surface plate 22. In addition, the housing 20 has a front surface plate 23 covering a front side of the engine 19. The upper surface plate 22 constitutes an upper structure, and is formed, for example, by mounting iron plates and other materials on frameworks composed of a plurality of steel materials.
The housing 20 has a support frame 24 (see
Next, the configuration of closed circuit systems 25 to 28 and open circuit systems 31 to 34 will be described.
In this embodiment, a hydraulic system of the hydraulic excavator 1 is configured to allow a closed-circuit control valve device 37 to connect any one closed-circuit hydraulic pump 29 to any one hydraulic actuator in the form of a closed circuit (to configure a closed circuit) between four closed-circuit hydraulic pumps 29, and four hydraulic actuators: the boom cylinder 16, the arm cylinder 17, the bucket cylinder 18 and the revolving hydraulic motor 7. Then, a controller 41 controls the closed-circuit control valve device 37, depending on the situations of operations and work, to control the switching between each of the hydraulic actuators and each of the closed-circuit hydraulic pumps 29.
In this embodiment, the case where each of the closed-circuit hydraulic pumps 29 is connected to each of the hydraulic actuators to configure four closed circuit systems will be described. Specifically, the closed circuit system 25 is a hydraulic system for driving the boom cylinder 16. The closed circuit system 26 is a hydraulic system for driving the arm cylinder 17. The closed circuit system 27 is a hydraulic system for driving the bucket cylinder 18. Further, the closed circuit system 28 is a hydraulic system for driving the revolving hydraulic motor 7. The configuration of these four most simplified closed circuit systems 25 to 28 will be described.
The closed circuit system 25 includes the closed-circuit hydraulic pumps 29 driven by the engine 19 and the closed-circuit pipe group 30 connecting the closed-circuit hydraulic pumps 29 and the boom cylinder 16. In addition, the closed circuit system 25 is provided with a later-described plurality of switching valves 37B to 37E of the closed-circuit control valve device 37 (see
Herein, the configuration of the closed circuit systems 26 to 28 is generally the same as that of the closed circuit system 25. Thus, in the closed circuit systems 26 to 28, the component elements that are identical to those of the closed circuit system 25 will be denoted by the same reference numerals to avoid repetitions of similar explanations.
As shown in
The closed-circuit pipe group 30 is configured to include a pair of two pump side pipes 30A and a pair of two actuator side pipes 30B. The pump side pipe 30A and the actuator side pipe 30B constitute a closed-circuit pipe. The pump side pipe 30A connects the closed-circuit hydraulic pump 29 for the boom cylinder 16 and a later-described closed-circuit control valve device 37. The actuator side pipe 30B connects the closed-circuit control valve device 37 and the boom cylinder 16 (bottom side oil chamber, rod side oil chamber).
The pump side pipe 30A of the closed-circuit pipe group 30 of the closed circuit system 26 connects the closed-circuit hydraulic pump 29 for the arm cylinder 17 and the closed-circuit control valve device 37. The actuator side pipe 30B of the closed-circuit pipe group 30 of the closed circuit system 26 connects the closed-circuit control valve device 37 and the arm cylinder 17. The pump side pipe 30A of the closed-circuit pipe group 30 of the closed circuit system 27 connects the closed-circuit hydraulic pump 29 for the bucket cylinder 18 and the closed-circuit control valve device 37. The actuator side pipe 30B of the closed-circuit pipe group 30 of the closed circuit system 27 connects the closed-circuit control valve device 37 and the bucket cylinder 18. Further, the pump side pipe 30A of the closed-circuit pipe group 30 of the closed circuit system 28 connects the closed-circuit hydraulic pump 29 for the revolving hydraulic motor 7 and the closed-circuit control valve device 37. The actuator side pipe 30B of the closed-circuit pipe group 30 of the closed circuit system 28 connects the closed-circuit control valve device 37 and the revolving hydraulic motor 7.
As described above, in this embodiment, it is possible to optionally switch the connection of any closed-circuit hydraulic pump 29 to any hydraulic actuator. Therefore, any closed-circuit hydraulic pump 29 and the pump side pipe 30A connected to the closed-circuit hydraulic pump 29 can selectively be connected to various hydraulic actuators, depending on the state of the closed-circuit control valve device 37.
Herein, the route of distribution for a closed-circuit pipe group 30, totaling eight pump side pipes 30A, composed of four pairs of two pipes for the four closed circuit systems 25 to 28, respectively, will be described. As shown in
Further, as shown in
Next, the open circuit system 31 is a hydraulic system for compensating for hydraulic oil relative to the closed circuit system 25. The open circuit system 32 is a hydraulic system for compensating for hydraulic oil relative to the closed circuit system 26. The open circuit system 33 is a hydraulic system for compensating for hydraulic oil relative to the closed circuit system 27. Further, the open circuit system 34 is a hydraulic system for compensating for hydraulic oil relative to the closed circuit system 28. In addition, each of the open circuit systems 31 to 34 supplies pressurized oil to the left and right traveling hydraulic motors 3, 4.
The open circuit system 31 includes the open-circuit hydraulic pump 35 driven by the engine 19 and an open-circuit pipe 36A connecting the open-circuit hydraulic pump 35 and the actuator side pipe 30B of the closed-circuit pipe group 30 of the closed circuit system 25. Also, the open circuit system 31 includes a later-described plurality of switching valves 38B to 38E (see
Herein, the configuration of the open circuit systems 32 to 34 is generally the same as that of the open circuit system 31. Thus, in the open circuit systems 32 to 34, the component elements that are identical to those of the open circuit system 31 will be denoted by the same reference numerals to avoid repetitions of similar explanations.
As shown in
The four open-circuit hydraulic pumps 35 that constitute the open circuit systems 31 to 34 supply pressurized oil to the left traveling hydraulic motor 3 and the right traveling hydraulic motor 4 via switching valves 38B to 38E.
The open-circuit pipe 36B of the open circuit system 32 connects the open-circuit hydraulic pump 35 and the actuator side pipe 30B of the closed-circuit pipe group 30 of the closed circuit system 26. In addition, a plurality of switching valves 38B to 38E is provided in the course of the open-circuit pipe 36B of the open circuit system 32. The open-circuit pipe 36C of the open circuit system 33 connects the open-circuit hydraulic pump 35 and the actuator side pipe 30B of the closed-circuit pipe group 30 of the closed circuit system 27. A plurality of switching valves 38B to 38E is provided in the course of the open-circuit pipe 36C of the open circuit system 33. Further, the open-circuit pipe 36D of the open circuit system 34 connects the open-circuit hydraulic pump 35 and the actuator side pipe 30B of the closed-circuit pipe group 30 of the closed circuit system 28. A plurality of switching valves 38B to 38E is provided in the course of the open-circuit pipe 36D of the open circuit system 34.
Herein, the route of distribution for the open-circuit pipe group 36, totaling four open-circuit pipes 36A to 36D, each provided for each of the open circuit systems 31 to 34, will be described. As shown in
In this way, in this embodiment, the closed-circuit pipe group 30 is distributed through upper positions of the closed-circuit hydraulic pump 29 and the open-circuit hydraulic pump 35 along the upper surface plate 22 of the housing 20, and the open-circuit pipe group 36 is distributed through lower positions of the closed-circuit hydraulic pump 29 and the open-circuit hydraulic pump 35 along the revolving frame 8. As a result, a space can be formed between the closed-circuit pipe group 30 and the open-circuit pipe group 36, which is defined between the front surface plate 23 of the housing 20, closed-circuit control valve device 37, and the open-circuit control valve device 38. The space is a working space including a later-described working passage 39.
The closed-circuit control valve device 37 and the open-circuit control valve device 38 are provided on the revolving frame 8 to be spaced apart forward from the front surface plate 23 of the housing 20, for example, arranged in parallel in the right-and-left direction. The closed-circuit control valve device 37 and the open-circuit control valve device 38 are arranged such that the former is located on the left side, and the latter is located on the right side, for example.
The closed-circuit control valve device 37 is composed of a block-shaped structure that is thin in the front-rear direction, including a manifold 37A (see
The open-circuit control valve device 38 is composed of a block-shaped structure that is thin in the front-rear direction, including a manifold 38A (see
A working passage 39 is a space for allowing an operator to work that is formed to extend in the right-and-left direction between the front surface plate 23 of the housing 20, the closed-circuit control valve device 37 and the open-circuit control valve device 38, which is defined between the closed-circuit pipe group 30 and the open-circuit pipe group 36. A foothold 39A that constitutes the working passage 39 faces the apparatuses such as the engine 19, the closed-circuit hydraulic pump 29, the open-circuit hydraulic pump 35, the closed-circuit control valve device 37, and the open-circuit control valve device 38. As a result, an operator in the working passage 39 can readily reach these apparatuses.
A hydraulic oil tank 40 is disposed on the revolving frame 8 to reserve hydraulic oil to be supplied to the open-circuit hydraulic pump 35 and the like. In addition, the controller 41 is connected to the operating device 11, the plurality of switching valves 37B to 37E of the closed-circuit control valve device 37 and the switching valves 38B to 38E of the open-circuit control valve device 38 via signal lines. The controller 41 switches between the switching valves 37B to 37E and the switching valves 38B to 38E based upon a signal from the operating device 11.
The hydraulic excavator 1 of this embodiment is configured as described above, and subsequently, the operation of the hydraulic excavator 1 will be explained.
An on-board operator in the cab 9 starts the engine 19 to drive the closed-circuit hydraulic pump 29 and the open-circuit hydraulic pump 35. In this state, the operator can advance or retreat the lower traveling structure 2 by operating the left and right traveling levers/pedals 11C, 11D. Meanwhile, the operator can perform excavating work of earth and sand by operating the left control lever 11A and the right control lever 11B to rotate the working mechanism 12.
Thus, in this embodiment, the closed-circuit pipe group 30 that constitutes the closed circuit systems 25 to 28 is distributed through upper positions of the closed-circuit hydraulic pump 29 and the open-circuit hydraulic pump 35 along the upper surface plate 22 of the housing 20. Further, the open-circuit pipe group 36 that constitutes the open circuit systems 31 to 34 is distributed through lower positions of the closed-circuit hydraulic pump 29 and the open-circuit hydraulic pump 35 along the revolving frame 8.
Therefore, the arrangement of the closed-circuit pipe group 30 and the open-circuit pipe group 36 can be simplified for distribution. As a result, a space can be formed between the closed-circuit pipe group 30 and the open-circuit pipe group 36.
Consequently, the space between the closed-circuit pipe group 30 and the open-circuit pipe group 36 can be secured as a working space to improve the operational efficiency. The distinct distribution of the closed-circuit pipe group 30 and the open-circuit pipe group 36 can disperse pump pulsation to reduce loads on structures near the closed-circuit pipe group 30 and the open-circuit pipe group 36.
The closed-circuit hydraulic pump 29 is located upward from the open-circuit hydraulic pump 35. As a result, the closed-circuit pipe group 30 can be guided from the upward located closed-circuit hydraulic pump 29 toward the upper surface plate 22 of the housing 20 in the shortest route. In addition, the open-circuit pipe group 36 can be guided from the downward located open-circuit hydraulic pump 35 toward the revolving frame 8 in the shortest route.
As a result, it can be easier to attach and remove the closed-circuit pipe group 30 for the closed-circuit hydraulic pump 29, maintain the closed-circuit hydraulic pump 29 and the like, attach and remove the open-circuit pipe group 36 for the open-circuit hydraulic pump 35 and maintain the open-circuit hydraulic pump 35 and the like. Moreover, the closed-circuit pipe group 30 and the open-circuit pipe group 36 can be shortened, thereby reducing pressure loss in the line.
Further, the foothold 39A that constitutes the working passage 39 facing the closed-circuit hydraulic pump 29 and the open-circuit hydraulic pump 35 is provided between the closed-circuit pipe group 30 and the open-circuit pipe group 36. As a result, the closed-circuit hydraulic pump 29, the open-circuit hydraulic pump 35, the closed-circuit control valve device 37, the open-circuit control valve device 38 and the like can readily be maintained from the foothold 39A of the working passage 39.
Moreover, the embodiments are explained by taking the example where a hydraulic excavator 1 with a backhoe-type working mechanism 12 is illustrated as a construction machine. However, the present invention is not limited to that, and may be widely employed in other types of construction machines such as a hydraulic excavator with a loading shovel-type working mechanism.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-053302 | Mar 2022 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2023/012281 | 3/27/2023 | WO |
