Construction Machinery

Abstract

A lower traveling body (15) is provided with travel-motor control valves (23) for controlling the flow of hydraulic oil to be fed from a hydraulic pump (10) to travel hydraulic motors (20). A hydraulic oil tank (12) and the travel hydraulic motors (20) are connected via hydraulic piping (25). The hydraulic piping (25) comprises: a feeding low-pressure piping part (25A), a pump-side high-pressure piping part (25B), and valve-side high-pressure piping parts (25C), which connect the hydraulic oil tank (12), the hydraulic pump (10), and the travel-motor control valves (23); switching high-pressure piping parts (25D, 25E), which are provided to the lower traveling body (15) and which connect the travel-motor control valves (23) and the travel hydraulic motors (20); and valve-side low-pressure piping parts (25F) and a tank-side low-pressure piping part (25G), which are provided so as to span from the lower traveling body (15) to an upper slewing body (3) and which connect the travel-motor control valves (23) and the hydraulic oil tank (12).

Description

[Technical field]

[0001] The present invention relates to a construction machine such as a hydraulic excavator. [Background technology]

[0002] Generally, a hydraulic excavator, which is a typical example of a construction machine, includes a self-propelled lower body and an upper rotating body that is rotatably mounted on the lower body via a rotating device. A working device for excavating earth and sand is rotatably mounted on the front side of the upper rotating body.

[0003] The upper rotating body is equipped with an engine as a prime mover, a hydraulic oil tank for storing hydraulic oil, a hydraulic pump that is driven by the engine to discharge the hydraulic oil stored in the hydraulic oil tank, and a travel motor control valve that controls the flow of the hydraulic oil discharged from the hydraulic pump and supplied to the traveling hydraulic motor. In addition, hydraulic piping is arranged in the upper rotating body and the lower traveling body to supply and discharge hydraulic oil from the hydraulic oil tank via the hydraulic pump etc. to the traveling hydraulic motor.

[0004] In recent years, there has been a demand for energy-saving hydraulic excavators. In this case, the hydraulic excavator is equipped with devices related to energy saving. Therefore, not only is the space for installing the devices on the upper rotating body of the hydraulic excavator limited, but the workability of the devices related to energy saving and the maintenance of existing devices is also deteriorated.

[0005] Therefore, some hydraulic excavators have the engine, hydraulic pump, fuel tank, and hydraulic oil tank, which are generally installed on the upper rotating body, moved to the lower traveling body (Patent Document 1). As a result, the hydraulic excavator in Patent Document 1 ensures installation space and working space on the upper rotating body. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Utility Model Application Publication No. 1-150653 Summary of the Invention

[0007] The hydraulic excavator according to Patent Document 1 is a small to medium-sized model, and the engine, hydraulic pump, fuel tank, hydraulic oil tank, etc. are sized according to the vehicle size. As a result, the engine, hydraulic pump, fuel tank, hydraulic oil tank, etc. are formed to a size that can be installed on the lower traveling body. However, in a large hydraulic excavator used for open-cut mining in mines, the engine, hydraulic pump, fuel tank, hydraulic oil tank, etc. become larger according to the vehicle size, so it is difficult to install the engine, hydraulic pump, fuel tank, hydraulic oil tank, etc. on the lower traveling body. As a result, the large hydraulic excavator cannot be made energy-efficient, and the installation space for the upper rotating body is limited, which leads to problems such as poor workability in maintenance, etc. In addition, when considering maintainability and the like, it is preferable that the hydraulic piping connecting the hydraulic oil tank and the traveling hydraulic motor be arranged as easily and with as much flexibility as possible while ensuring the strength to withstand the pressure of the hydraulic oil circulating within the piping.

[0008] The present invention has been made in consideration of the problems with the prior art described above, and an object of the present invention is to provide a construction machine which ensures space for mounting various equipment on the upper rotating body, facilitates the layout of hydraulic piping connecting hydraulic equipment, and improves the ease of maintenance and other operability.

[0009] The present invention relates to a construction machine comprising a lower traveling body capable of self-propelling by a traveling hydraulic motor, and an upper rotating body provided on the lower traveling body so as to be rotatable via a rotating device, the upper rotating body comprising a prime mover, a hydraulic oil tank, and a hydraulic pump that is driven by the prime mover to discharge hydraulic oil stored in the hydraulic oil tank. The lower traveling body is provided with a traveling motor control valve that controls the flow of hydraulic oil supplied from the hydraulic pump to the traveling hydraulic motor, the hydraulic oil tank and the traveling hydraulic motor are connected by hydraulic piping, and the hydraulic piping controls the hydraulic oil tank. The hydraulic oil tank is provided with a supply piping section that connects an oil tank, the hydraulic pump, and the travel motor control valve to supply hydraulic oil; a high-pressure piping section that is provided on the lower travel body, connects the travel motor control valve and the travel hydraulic motor, and through which high-pressure hydraulic oil discharged from the hydraulic pump and supplied to the travel hydraulic motor flows; and a low-pressure piping section that is provided from the lower travel body to the upper rotating body, connects the travel motor control valve and the hydraulic oil tank, and through which low-pressure hydraulic oil flows that is discharged from the travel hydraulic motor and returned to the hydraulic oil tank from the travel motor control valve.

[0010] According to the present invention, it is possible to secure installation space for equipment on the upper rotating body, and for example, equipment for energy saving can be installed. In addition, it is possible to increase the proportion of low-pressure piping, which is easy to arrange, among hydraulic piping, and it is possible to secure work space for maintenance, etc., and improve workability. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a right side view showing a hydraulic excavator according to an embodiment of the present invention. [Diagram 2] FIG. [Diagram 3] 3 is a rear view of the lower traveling body as viewed from the direction of arrows III-III in FIG. 2. [Figure 4] 4 is a cross-sectional view showing a rear portion of a lower running body as viewed from the direction of arrows IV-IV in FIG. 2. [Diagram 5]FIG. 2 is a schematic diagram showing a supply path and a return path of hydraulic oil to a traveling hydraulic motor. [Figure 6] FIG. 11 is a schematic diagram showing a supply path and a return path of hydraulic oil to a traveling hydraulic motor according to a comparative example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, a hydraulic excavator will be taken as an example and described in detail with reference to Figs. 1 to 6 as a representative example of a construction machine according to an embodiment of the present invention.

[0013] In Fig. 1, a hydraulic excavator 1, which is a representative example of a construction machine, is an extra-large hydraulic excavator (mining hydraulic excavator) used for excavating mines (open cut mining), etc. The hydraulic excavator 1 includes a lower traveling body 15 described below, an upper rotating body 3 rotatably mounted on the lower traveling body 15 via a rotating device 2, and a working device 4 rotatably mounted on the front side of the upper rotating body 3 and used for excavating earth and sand, etc.

[0014] The slewing device 2 is a mechanism for rotating the upper slewing body 3 on the lower traveling body 15. The slewing device 2 includes a slewing ring 2A made of an annular bearing provided between the track frame 16 of the lower traveling body 15 and the slewing frame 5 of the upper slewing body 3, and a slewing motor (not shown) that meshes with the inner ring of the slewing ring 2A to rotate the upper slewing body 3.

[0015] The upper rotating body 3 comprises a rotating frame 5 which forms a support structure and has a working device 4 mounted on the front side thereof, a cab 6 which is mounted on the front left side of the rotating frame 5 and forms an operator's cabin inside, a counterweight 7 which is attached to the rear of the rotating frame 5 and balances the weight with the working device 4, and a building 8 which is located between the cab 6 and the counterweight 7 and which houses an engine 9 (described below) mounted on the rotating frame 5 and the like. Inside the cab 6, there is provided a driver's seat where an operator sits, and operating devices (none of which are shown) which are located in front of, to the left and right of the driver's seat and which operate the hydraulic excavator 1.

[0016] The engine 9 as a prime mover is located on the revolving frame 5, in front of the counterweight 7. The engine 9 is configured as, for example, a diesel engine. One engine 9 is provided horizontally extending in the left-right direction on the rear side of the revolving frame 5. For example, a hydraulic pump 10, which will be described later, is attached to the right side of the engine 9. In addition, a heat exchanger including a radiator, an oil cooler, a condenser, etc. (none of which are shown) is disposed on the left side of the engine 9.

[0017] The prime mover may be a hybrid prime mover that combines a diesel engine and an electric motor, or an electric motor alone. Alternatively, the prime mover may be provided in a vertically mounted state extending in the front-rear direction of the upper rotating body 3. Also, two prime movers may be mounted side by side in the left-right direction.

[0018] The hydraulic pump 10 is attached to the right of the engine 9. The hydraulic pump 10 includes a main pump that discharges hydraulic oil (pressurized oil) for operating the hydraulic actuators of the working device 4, the swing motor of the swing device 2, the traveling hydraulic motor 20 of the lower traveling body 15, etc., and a pilot pump that discharges hydraulic oil (pressurized oil) for operating control valves (including the traveling motor control valve 23) that control these hydraulic actuators. The multiple hydraulic pumps 10 are configured, for example, by a variable displacement swash plate type hydraulic pump, a bent axis type hydraulic pump, a radial piston type hydraulic pump, etc.

[0019] The center joint 11 is located at the center of a slewing ring 2A (cylindrical portion 17A of a center frame 17 described later) of the slewing device 2, which serves as the center of rotation, and is provided between the lower running body 15 and the upper rotating body 3. Even when the upper rotating body 3 is rotating relative to the lower running body 15, the center joint 11 allows the circulation of hydraulic oil for operating the hydraulic actuators, pilot hydraulic oil for operating the travel motor control valve 23 and the like, and electricity (signals) between the lower running body 15 and the upper rotating body 3.

[0020] The center joint 11 includes a body attached to the revolving frame 5 of the upper revolving body 3, and a spindle rotatably provided within the body while protruding downward from the body and attached to a track frame 16 of the lower traveling body 15. The center joint 11 also has a plurality of annular oil passages extending in the circumferential direction between the body and the spindle, and a plurality of oil passages (none of which are shown) that open to the outer surfaces of the body and the spindle and are individually connected to the plurality of annular oil passages.

[0021] The body is connected to pump-side high-pressure piping 25B, tank-side low-pressure piping 25G, pump-side pilot piping, pump-side harness (none of which are shown), etc. On the other hand, the spindle is connected to valve-side high-pressure piping 25C, valve-side low-pressure piping 25F, valve-side pilot piping, valve-side harness (none of which are shown), etc.

[0022] 5, the hydraulic oil tank 12 stores hydraulic oil to be supplied to the hydraulic pump 10, and is provided on the revolving frame 5. The hydraulic oil tank 12 is connected to the hydraulic pump 10 via a low-pressure supply piping section 25A, which will be described later. In addition, the hydraulic oil tank 12 is connected to a tank-side low-pressure piping section 25G.

[0023] The control valve device 13 is located in front of the engine 9 and is provided on the revolving frame 5. The control valve device 13 is configured to include, for example, a manifold made of a block-shaped structure and a plurality of control valves attached to the manifold. The control valve device 13 (control valve) controls the flow of hydraulic oil supplied from the hydraulic pump 10 to the hydraulic actuator of the working device 4 and the revolving motor of the revolving device 2.

[0024] Here, the control valve device 13 can be made smaller by the amount of the travel motor control valve 23, which will be described later, being relocated to the undercarriage 15 side. Moreover, in order to install the travel motor control valve 23, space is required for the connections of the piping and hoses for the travel motor control valve 23, and for maintenance between the control valve device 13 and surrounding valves and structures. In contrast, by relocating the travel motor control valve 23, this space can be omitted, making it possible to make the control valve device 13 even more compact.

[0025] The pilot control valve device 14 is provided on the revolving frame 5, for example, at a position rearward of the control valve device 13. Like the control valve device 13, the pilot control valve device 14 is configured to include a manifold and a plurality of control valves. The pilot control valve device 14 controls the flow of pilot hydraulic oil supplied to the control valve of the control valve device 13 and a travel motor control valve 23 described below. The pilot control valve device 14 can also be installed in the undercarriage 15.

[0026] The lower traveling body 15 travels by rotating the drive wheels 19 using a traveling hydraulic motor 20 described below. The lower traveling body 15 includes a track frame 16, drive wheels 19, a traveling hydraulic motor 20, idler wheels 21, tracks 22, a traveling motor control valve 23, a brake valve 24, and hydraulic piping 25, all of which will be described below.

[0027] The truck frame 16 includes a center frame 17 located in the center, and side frames 18 (see Figs. 1 and 4) provided on both the left and right sides of the center frame 17. The center frame 17 has a cylindrical portion 17A located in the center and protruding upward, and the slewing wheel 2A of the slewing device 2 is attached to the cylindrical portion 17A. The center frame 17 includes a center joint 11 at the center position of the cylindrical portion 17A. As shown in Fig. 2, the center frame 17 includes front legs 17B located on the front side (idler wheel 21 side) and extending to both the left and right sides, and rear legs 17C located on the rear side (drive wheel 19 side) and extending to both the left and right sides.

[0028] 3, the rear surfaces of the left and right rear legs 17C of the center frame 17 serve as valve mounting surfaces 17D. A travel motor control valve 23 and a brake valve 24, which will be described later, are attached to these valve mounting surfaces 17D, which are disposed opposite the travel hydraulic motor 20 in the front-rear direction.

[0029] The side frames 18 are provided extending in the front-to-rear direction on both the left and right sides of the center frame 17, specifically, on the tips of the left front leg 17B and rear leg 17C and on the right front leg 17B and rear leg 17C.

[0030] As shown in Figures 1 and 4, the drive wheels 19 are provided at the rear of the side frames 18. The drive wheels 19 are composed of a reduction gear, a drive tumbler (or sprocket), etc., and the reduction gear is attached to the rear of the side frames 18. A hydraulic motor 20 for traveling, which will be described later, is attached to the drive wheels 19.

[0031] As shown in FIG. 4, the traveling hydraulic motors 20 are attached, for example, two in number, side by side in the front-rear direction, on the inside of the left-right direction of the drive wheels 19. As a result, the two traveling hydraulic motors 20 attached to the left drive wheel 19 and the two traveling hydraulic motors 20 attached to the right drive wheel 19 protrude inward from the drive wheels 19 so as to face each other (see FIG. 2 and FIG. 3). The traveling hydraulic motors 20 are configured, for example, by a variable displacement swash plate type hydraulic motor, a slanted axis type hydraulic motor, a radial piston type hydraulic motor, or the like. The traveling hydraulic motor 20 rotates a rotating shaft (not shown) by being supplied with hydraulic oil (pressure oil) from the traveling motor control valve 23 via switching high pressure piping sections 25D, 25E, and the resulting rotational force rotates the drive wheels 19 via a reduction gear. Note that one or more traveling hydraulic motors 20 may be provided depending on the required output.

[0032] The idler wheel 21 is rotatably provided at the front of the side frame 18 on the opposite side in the front-rear direction to the drive wheel 19 (only the right side is shown in FIG. 1). In addition, the crawler belt 22 is wound around the drive wheel 19 and the idler wheel 21 so as to be able to rotate.

[0033] Here, the drive wheels 19 are arranged on the rear side of the lower running structure 15 so that the ground side of the crawler belt 22 is taut during forward running, which is frequently used, and the front-rear direction is determined based on this. The front-rear direction of the lower running structure 15 is the forward and reverse directions of the lower running structure 15. On the other hand, when the upper rotating structure 3 rotates 180 degrees on the lower running structure 15, the front-rear direction is opposite when viewed from the upper rotating structure 3.

[0034] The travel motor control valves 23 are attached to the lower travel body 15. Two travel motor control valves 23 are attached to the left valve mounting surface 17D corresponding to the two travel hydraulic motors 20 provided on the left drive wheel 19, and two travel motor control valves 23 are attached to the right valve mounting surface 17D corresponding to the two travel hydraulic motors 20 provided on the right drive wheel 19. The travel motor control valve 23 is a hydraulic pilot type switching valve that controls the flow of hydraulic oil supplied from the hydraulic pump 10 to the travel hydraulic motor 20. In other words, the travel motor control valve 23 can switch the rotation direction (forward rotation, reverse rotation) of the travel hydraulic motor 20.

[0035] As shown in Fig. 3, the two travel motor control valves 23 are provided at positions shifted in the left-right and up-down directions. Specifically, the travel motor control valve 23 located inside in the left-right direction is located at a higher position than the travel motor control valve 23 located outside in the left-right direction. As a result, even when two travel motor control valves 23 are arranged side by side, by changing the height position, a work space can be secured and maintenance such as inspection, repair, and replacement can be easily performed. In addition, by providing a total of four travel motor control valves 23 in the lower traveling body 15, the control valve device 13 can be made smaller by the amount of the four travel motor control valves 23.

[0036] Moreover, by installing the traveling motor control valve 23 using the rear surface of the center frame 17, it can be disposed in a position intermediate between the center joint 11 and the traveling hydraulic motor 20. With this configuration, the hydraulic piping 25 can be arranged in a short and orderly manner, improving the workability of assembly work, maintenance, etc. Also, the traveling motor control valve 23 provided on the rear surface of the center frame 17 allows for easy maintenance.

[0037] The brake valves 24 are attached to the lower traveling body 15 via the traveling motor control valve 23. Similar to the traveling motor control valve 23, the brake valves 24 correspond to the two traveling hydraulic motors 20 provided on the left driving wheel 19, and two of them are attached to the left traveling motor control valve 23 in a stacked manner. In addition, the brake valves 24 correspond to the two traveling hydraulic motors 20 provided on the right driving wheel 19, and two of them are attached to the right traveling motor control valve 23 in a stacked manner. The brake valves 24 apply braking to the traveling hydraulic motors 20 by restricting the flow of hydraulic oil.

[0038] Furthermore, like the travel motor control valve 23, the brake valves 24 located on the inside are positioned higher than the brake valves 24 located on the outside. This ensures that even when two brake valves 24 are positioned side by side, work space can be secured and maintenance such as inspection, repair, and replacement can be easily performed. Also, because the brake valve 24 is attached to the travel motor control valve 23 in a stacked manner, no attachment space is required on the valve attachment surface 17D, and piping connecting the travel motor control valve 23 and the brake valve 24 can be omitted.

[0039] As shown typically in Fig. 5, hydraulic piping 25 connects the hydraulic oil tank 12 and the traveling hydraulic motor 20 via the hydraulic pump 10, the center joint 11, the traveling motor control valve 23, and the brake valve 24. The hydraulic piping 25 also includes a high-pressure piping section (thick line in Fig. 5) through which high-pressure hydraulic oil discharged from the hydraulic pump 10 flows, and a low-pressure piping section (thin line in Fig. 5) through which low-pressure hydraulic oil returned from the traveling motor control valve 23 to the hydraulic oil tank 12 flows. Four sets of hydraulic piping 25 are provided to correspond to a total of four traveling hydraulic motors 20 (one set on the supply side and one set on the return side x 4).

[0040] The configuration of the hydraulic piping 25 will be specifically described along the flow direction of the hydraulic oil. The hydraulic piping 25 is composed of a supply low pressure piping section (supply piping section) 25A connecting the hydraulic oil tank 12 and the hydraulic pump 10, a pump side high pressure piping section (supply piping section) 25B connecting the hydraulic pump 10 and the center joint 11, a valve side high pressure piping section (supply piping section) 25C connecting the center joint 11 and the travel motor control valve 23, two switching high pressure piping sections (high pressure piping sections) 25D, 25E ​​connecting the brake valve 24 and the travel hydraulic motor 20, a valve side low pressure piping section (low pressure piping section) 25F connecting the travel motor control valve 23 and the center joint 11, and a tank side low pressure piping section (low pressure piping section) 25G connecting the center joint 11 and the hydraulic oil tank 12. Of the two switching high pressure pipes 25D, 25E, one serves as a supply side through which high pressure hydraulic oil flows, and the other serves as a return side through which low pressure hydraulic oil flows.

[0041] The high-pressure piping section, consisting of pump-side high-pressure piping section 25B, valve-side high-pressure piping section 25C, and two switching high-pressure piping sections 25D and 25E, is made of highly durable materials and structures so as to withstand the pressure of the hydraulic oil discharged from hydraulic pump 10. The piping used in the high-pressure piping section includes metal piping and hoses. When the high-pressure piping section is metal piping, a thick metal pipe or a metal pipe made of a material with high strength is used. When the high-pressure piping section is a hose, a thick pressure-resistant hose made of multiple layers of strong material stacked in the radial direction is used. Therefore, the high-pressure piping section requires more space for routing than the low-pressure piping section, is expensive, and is difficult to process and handle.

[0042] The low-pressure piping section, which is composed of the supply low-pressure piping section 25A, the valve-side low-pressure piping section 25F, and the tank-side low-pressure piping section 25G, only needs to have durability that can withstand the pressure when the hydraulic oil that is returned to the hydraulic oil tank 12 at atmospheric pressure flows. The piping used in the low-pressure piping section includes metal piping and hoses, similar to the high-pressure piping section. When the low-pressure piping section is a metal piping, a metal pipe or the like that is thin and low in strength can be used. When the low-pressure piping section is a hose, a hose with low durability can be used. Therefore, compared to the high-pressure piping section, the low-pressure piping section can reduce the installation space by using thin piping and hoses, and has a high degree of freedom in installation such as bending, and is inexpensive and easy to process and handle.

[0043] Of the hydraulic piping 25, the valve-side high-pressure piping section 25C and the valve-side low-pressure piping section 25F, which are arranged in the center frame 17, extend upward from the travel motor control valve 23 along the valve mounting surface 17D, then bend at the position of the upper surface of the rear leg section 17C and extend forward, bend toward the cylindrical section 17A at the side of the cylindrical section 17A, and connect to the center joint 11 by passing through the side of the cylindrical section 17A.

[0044] 2, of the low-pressure piping sections, the valve-side low-pressure piping section 25F between the center joint 11 and the traveling motor control valve 23 is routed through a position farther from the crawler belt 22 of the lower traveling body 15 than the valve-side high-pressure piping section 25C extending in parallel therewith. In other words, the valve-side low-pressure piping section 25F is routed through a position closer to the cylindrical section 17A of the center frame 17 (the slewing ring 2A of the slewing device 2) than the valve-side high-pressure piping section 25C.

[0045] As a result, even if a stone or piece of concrete bounces off the track 22 and flies toward the center frame 17, the high-strength valve-side high-pressure piping section 25C is arranged in a position close to the track 22, so that the valve-side low-pressure piping section 25F can be protected from the stone, concrete piece, etc.

[0046] FIG. 6 shows a comparative example, in which a travel motor control valve 101 is provided on the upper rotating body 3. Therefore, the hydraulic piping 102 of the comparative example is composed of a supply low pressure piping section 102A connecting the hydraulic oil tank 12 and the hydraulic pump 10, a first pump side high pressure piping section 102B connecting the hydraulic pump 10 and the travel motor control valve 101, a second pump side high pressure piping section 102C connecting the travel motor control valve 101 and the center joint 11, a valve side high pressure piping section 102D connecting the center joint 11 and the brake valve 24, motor side high pressure piping sections 102E, 102F connecting the brake valve 24 and the travel hydraulic motor 20, a valve side high pressure piping section 102G connecting the brake valve 24 and the center joint 11, a tank side high pressure piping section 102H connecting the center joint 11 and the travel motor control valve 101, and a tank side low pressure piping section 102J connecting the travel motor control valve 101 and the hydraulic oil tank 12.

[0047] In this case, the path through which high-pressure hydraulic oil flows is switched between the travel motor control valve 101 and the travel hydraulic motor 20 in response to switching between forward and reverse rotation of the travel hydraulic motor 20. For this reason, all piping between the travel motor control valve 101 and the travel hydraulic motor 20 is a high-pressure piping section. In other words, the low-pressure piping sections in the comparative example in Figure 6 are only the supply low-pressure piping section 102A and the tank-side low-pressure piping section 102J.

[0048] In contrast, in the present embodiment shown in Fig. 5, a larger portion can be made into a low-pressure piping section compared to the comparative example in Fig. 6 (i.e., a case where a travel motor control valve 101 is provided on the upper rotating body 3). Specifically, the hydraulic piping 25 can have the supply low-pressure piping section 25A, the valve-side low-pressure piping section 25F, and the tank-side low-pressure piping section 25G as low-pressure piping sections. That is, in this embodiment, the proportion of the low-pressure piping section, which has ease and freedom in routing, in the entire piping length of the hydraulic piping 25 can be significantly increased. Therefore, in this embodiment, the freedom and ease of routing the hydraulic piping 25 as a whole is significantly improved.

[0049] For example, in this embodiment, the tank-side low-pressure piping section 25G, i.e., the piping connecting the center joint 11 and the hydraulic oil tank 12, can be routed directly (without passing through the travel motor control valve 23) within the upper rotating body 3. Therefore, for example, the tank-side low-pressure piping section 25G can be made shorter in piping length than the tank-side high-pressure piping section 102H and the tank-side low-pressure piping section 102J in the comparative example.

[0050] The hydraulic excavator 1 according to this embodiment has the above-mentioned configuration, and its operation will now be described.

[0051] The operator in the cab 6 starts the engine 9 to drive the hydraulic pump 10. In this state, the operator can move the lower traveling structure 15 forward or backward by operating the operating device for traveling. In addition, the operator can rotate the working device 4 to perform work such as excavating earth and sand by operating the operating device for work.

[0052] Here, the flow of hydraulic oil when the lower traveling body 15 is traveling will be described. When the hydraulic pump 10 is driven by the engine 9 and hydraulic oil is supplied from the hydraulic oil tank 12 to the hydraulic pump 10 through the supply low pressure piping section 25A, high pressure hydraulic oil is discharged from the hydraulic pump 10 and is supplied to the traveling motor control valve 23 through a supply piping section consisting of the pump side high pressure piping section 25B and the valve side high pressure piping section 25C. The traveling motor control valve 23 is switched based on a control signal supplied through a pilot piping section, and supplies hydraulic oil to the traveling hydraulic motor 20 from, for example, the switching high pressure piping section 25D (high pressure piping section). On the other hand, the hydraulic oil that has driven the traveling hydraulic motor 20 is returned to the traveling motor control valve 23 through the switching high pressure piping section 25E and is returned to the hydraulic oil tank 12 through a low pressure piping section consisting of the valve side low pressure piping section 25F and the tank side low pressure piping section 25G.

[0053] Thus, in this embodiment, the hydraulic excavator 1 includes a lower traveling body 15 capable of self-propelling by a traveling hydraulic motor 20, and an upper rotating body 3 provided on the lower traveling body 15 so as to be able to rotate via a rotating device 2. A traveling motor control valve 23 is provided on the lower traveling body 15 to control the flow of hydraulic oil supplied from the hydraulic pump 10 to the traveling hydraulic motor 20, and the traveling motor control valve 23 is attached to the lower traveling body 15.

[0054] Therefore, the control valve device 13 mounted on the upper rotating body 3 can be made smaller by the size of the travel motor control valve 23, and therefore installation space can be secured in the upper rotating body 3 by the size of the control valve device 13. Furthermore, space can be secured in the upper rotating body 3 for inspecting, repairing, and replacing the mounted devices such as the engine 9, hydraulic pump 10, and control valve device 13. As a result, space can be secured for installing devices required to make the hydraulic excavator 1 energy efficient, and the workability can be improved when maintaining the devices including the energy efficient devices.

[0055] Moreover, in this embodiment, the hydraulic oil tank 12 and the traveling hydraulic motor 20 are connected by hydraulic piping 25 . The hydraulic piping 25 includes a supply low pressure piping section 25A, a pump side high pressure piping section 25B, and a valve side high pressure piping section 25C as supply piping sections that connect the hydraulic oil tank 12, the hydraulic pump 10, and the traveling motor control valve 23 to supply hydraulic oil, two switching high pressure piping sections 25D, 25E ​​that are provided in the lower traveling body 15 and connect the traveling motor control valve 23 and the traveling hydraulic motor 20, and serve as high pressure piping sections through which the high pressure hydraulic oil discharged from the hydraulic pump 10 and supplied to the traveling hydraulic motor 20 flows, and a valve side low pressure piping section 25F and a tank side low pressure piping section 25G that are provided from the lower traveling body 15 to the upper rotating body 3, and connect the traveling motor control valve 23 and the hydraulic oil tank 12, and serve as low pressure piping sections through which the low pressure hydraulic oil discharged from the traveling hydraulic motor 20 and returning from the traveling motor control valve 23 to the hydraulic oil tank 12 flows.

[0056] Therefore, in this embodiment, the low pressure piping section accounts for a larger proportion of the overall length of the hydraulic piping 25 (the high pressure piping section accounts for a smaller proportion), which not only improves the freedom of routing, ease of routing, and ease of attachment and detachment of the hydraulic piping 25 as a whole, but also improves maintainability and reduces costs.

[0057] The lower traveling body 15 comprises a track frame 16 having a center frame 17 and side frames 18 extending in the front-rear direction on both the left and right sides of the center frame 17, drive wheels 19 provided at the rear of the side frames 18 and rotated by a traveling hydraulic motor 20, idler wheels 21 provided at the front of the side frames 18, and a track 22 wound around the drive wheels 19 and the idler wheels 21. The center frame 17 also comprises a valve mounting surface 17D on its rear surface facing the traveling hydraulic motor 20 in the front-rear direction. A traveling motor control valve 23 is attached to the valve mounting surface 17D of the center frame 17.

[0058] Therefore, by installing the traveling motor control valve 23 using the rear surface of the center frame 17, it can be disposed in a position intermediate between the center joint 11 and the traveling hydraulic motor 20. This allows the hydraulic piping 25 to be short and neatly routed, improving the workability of assembly work, maintenance, etc. Also, the traveling motor control valve 23 provided on the rear surface of the center frame 17 is easily accessible, facilitating maintenance.

[0059] A center joint 11 for circulating hydraulic oil between the lower traveling body 15 and the upper traveling body 3 is provided at the center of the rotation of the rotating device 2. The lower traveling body 15 is provided with a brake valve 24 for applying braking to the traveling hydraulic motor 20. The hydraulic piping 25 is provided to connect the hydraulic oil tank 12 and the traveling hydraulic motor 20 via the hydraulic pump 10, the center joint 11, the traveling motor control valve 23, and the brake valve 24. In addition, a valve-side low-pressure piping section 25F and a tank-side low-pressure piping section 25G as low-pressure piping sections are provided between the upper traveling body 3 and the lower traveling body 15 via the center joint 11. In addition, among the low-pressure piping sections, the valve-side low-pressure piping section 25F between the center joint 11 and the traveling motor control valve 23 is routed through a position farther from the crawler belt 22 than the valve-side high-pressure piping section 25C as the high-pressure piping section.

[0060] As a result, even if a stone or piece of concrete bounces off the crawler belt 22 and flies toward the center frame 17, the valve-side high-pressure piping section 25C made of high-strength piping is disposed in a position close to the crawler belt 22. As a result, the valve-side low-pressure piping section 25F is far from the direction in which the stone or piece of concrete will fly, and the valve-side high-pressure piping section 25C acts as a wall, so that the valve-side low-pressure piping section 25F can be protected from the stone, concrete, etc.

[0061] The travel motor control valves 23 are provided in multiple positions aligned in the left-right direction and shifted in the up-down direction, for example, two on each side. As a result, even if two travel motor control valves 23 are arranged close to each other, by changing the height position, a working space for hanging tools and the like can be secured, making it easy to perform maintenance such as inspection, repair, and replacement.

[0062] In the embodiment, the valve side high pressure piping section 25C and the valve side low pressure piping section 25F of the hydraulic piping 25 are configured to pass through the side section (side frame 18 side) of the cylindrical section 17A of the center frame 17. However, the present invention is not limited to this configuration, and for example, the valve side high pressure piping section and the valve side low pressure piping section of the hydraulic piping may be configured to pass through the rear section of the cylindrical section of the center frame.

[0063] In the embodiment, the traveling motor control valve 23 is attached to the valve mounting surface 17D of the center frame 17, and the brake valve 24 is attached overlapping the traveling motor control valve 23. However, the present invention is not limited to this, and for example, the brake valve may be directly attached to the valve mounting surface of the center frame. In this case, the traveling motor control valve and the brake valve are connected by a high-pressure piping section.

[0064] In the embodiment, the hydraulic excavator 1 equipped with a backhoe-type working implement 4 has been taken as an example of the construction machine. However, the present invention is not limited to this, and can be widely applied to other construction machines such as hydraulic excavators equipped with a loading shovel-type working implement. [Explanation of symbols]

[0065] 1. Hydraulic excavator (construction machinery) 2 Swivel device 3. Upper rotating body 9 Engine (prime mover) 10 Hydraulic pump 11 Center joint 12 Hydraulic Oil Tank 15 Undercarriage 16 Truck Frame 17 Center Frame 17D Valve mounting surface 18 Side frame 19 Drive Wheel 20 Hydraulic motor for driving 21 Idler 22 Tracks 23 Control valve for driving motor 24 Brake valve 25 Hydraulic piping 25A Low pressure supply piping section (supply piping section) 25B Pump side high pressure piping (supply piping) 25C Valve side high pressure piping section (supply piping section) 25D Switching high pressure piping section (high pressure piping section) 25E High pressure switching piping section (high pressure piping section) 25F Valve side low pressure piping section (low pressure piping section) 25G Tank side low pressure piping section (low pressure piping section)

Claims

1. The vehicle comprises a lower traveling body capable of self-propelling by a traveling hydraulic motor, and an upper rotating body provided on the lower traveling body so as to be rotatable via a rotating device, The upper rotating body is a construction machine including a prime mover, a hydraulic oil tank, and a hydraulic pump that is driven by the prime mover to discharge hydraulic oil stored in the hydraulic oil tank, The lower traveling body is provided with a traveling motor control valve that controls a flow of hydraulic oil supplied from the hydraulic pump to the traveling hydraulic motor, The hydraulic oil tank and the traveling hydraulic motor are connected by hydraulic piping, The hydraulic piping includes: a supply piping section that connects the hydraulic oil tank, the hydraulic pump, and the travel motor control valve to supply hydraulic oil; a high-pressure piping section that is provided on the lower traveling body, that connects the traveling motor control valve and the traveling hydraulic motor, through which high-pressure hydraulic oil discharged from the hydraulic pump and supplied to the traveling hydraulic motor flows; a low-pressure piping section that is provided from the lower traveling body to the upper rotating body, that connects the traveling motor control valve and the hydraulic oil tank, and through which low-pressure hydraulic oil flows that is discharged from the traveling hydraulic motor and returned to the hydraulic oil tank from the traveling motor control valve.

2. 2. The construction machine according to claim 1, the lower traveling body comprises a track frame having a center frame and side frames extending in a front-rear direction on both left and right sides of the center frame, drive wheels provided at rear portions of the side frames and rotated by the traveling hydraulic motor, idler wheels provided at front portions of the side frames, and tracks wound around the drive wheels and the idler wheels, the center frame has a valve mounting surface on a rear surface facing the traveling hydraulic motor in the front-rear direction, 2. A construction machine comprising: a control valve for a travel motor; and a valve mounting surface of the center frame.

3. The construction machine according to claim 2, a center joint for circulating hydraulic oil between the lower traveling body and the upper rotating body is provided at a rotation center position of the rotating device, The low pressure piping section is provided between the upper rotating body and the lower traveling body via the center joint, a valve-side low-pressure piping section between the center joint and the traveling motor control valve, among the low-pressure piping section, arranged at a position farther from the crawler belt than the high-pressure piping section.

4. 2. The construction machine according to claim 1, A construction machine characterized in that the travel motor control valve is provided in a plurality of positions aligned in the left-right direction and shifted in the up-down direction.

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