Construction Machinery

Abstract

To provide an angle sensor in a center joint in a state of protected from an external force.SOLUTION: A hydraulic shovel 1 includes a center joint 11 for allowing pressure oil to flow between a hydraulic pump 10, and a hydraulic oil tank and a hydraulic motor 2F for traveling, and an angle sensor 30 for detecting a turning angle of an upper turning body 4 relative to a lower traveling body 2. The center joint 11 includes a cylindrical body 12, and a spindle 17 rotatably fitted to the inner peripheral side of the body 12, and a cover member 22 for covering the fitting part between the body 12 and the spindle 17 from above is provided on the upper end side of the center joint 11. The angle sensor 30 is provided between the cover member 22 and the spindle 17. Thus, the collision of a falling rock, dust and the like with the angle sensor 30 can be suppressed by the cover member 22.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a construction machine, such as a hydraulic excavator, in which a center joint is provided between a lower traveling body and an upper rotating body. [Background technology]

[0002] Generally, a hydraulic excavator, which is a representative example of construction machinery, is configured with a self-propelled lower traveling body equipped with a hydraulic motor for traveling, an upper rotating body rotatably mounted on the lower traveling body, and a working device mounted on the upper rotating body, and performs work such as excavating earth and sand using the working device. The upper rotating body is rotatably mounted on the lower traveling body via a slewing ring, and is provided with a hydraulic pump that discharges hydraulic oil stored in a hydraulic oil tank as pressurized oil. A center joint is provided between the lower traveling body and the upper rotating body, located at the center of rotation of the upper rotating body.

[0003] The center joint distributes pressure oil between a hydraulic motor for traveling provided on the lower traveling body and a hydraulic pump and hydraulic oil tank provided on the upper rotating body. To improve operability during a swing operation, an operator needs to accurately grasp the swing angle of the upper rotating body relative to the lower traveling body. For this reason, an angle sensor is usually provided on the center joint of a hydraulic excavator, and this angle sensor detects the swing angle of the upper rotating body relative to the lower traveling body (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-82494 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the hydraulic excavator disclosed in Patent Document 1, an angle sensor is provided at the upper end of the center joint. However, since the upper end of the center joint protrudes upward from the rotating frame that forms the base of the upper rotating body, it is constantly exposed to rocks (falling rocks) that fall from the bucket during excavation work, dust, wind, rain, etc. Therefore, if the angle sensor, which is a precision instrument, is placed at the upper end of the center joint, there is a problem that the angle sensor is prone to failure due to the external force applied to the angle sensor by falling rocks, dust, wind, rain, etc.

[0006] An object of the present invention is to provide a construction machine in which an angle sensor can be mounted in a center joint while being protected from external forces. [Means for solving the problem]

[0007] The present invention relates to a construction machine comprising a self-propelled lower running body provided with a hydraulic motor for traveling, an upper rotating body rotatably provided on the lower running body, a hydraulic pump provided on the upper rotating body and discharging hydraulic oil in a hydraulic oil tank mounted on the upper rotating body as pressurized oil, a center joint located at the center of rotation of the upper rotating body and provided between the upper rotating body and the lower running body, for circulating pressurized oil between the hydraulic pump, the hydraulic oil tank and the hydraulic motor, and an angle sensor for detecting the rotation angle of the upper rotating body relative to the lower running body, the center joint including a cylindrical body attached to the upper rotating body, and a spindle attached to the lower running body and rotatably fitted to the inner periphery of the body, a cover member is provided on the upper end side of the center joint for covering from above a fitting portion between the body and the spindle, and the angle sensor is provided between the cover member and the spindle. Placed R The spindle is provided with a drain passage for returning drain oil from the hydraulic motor to the hydraulic oil tank, the cover member is provided with a drain port to which a drain hose for returning the drain oil to the hydraulic oil tank is connected, and a drain inlet chamber for communicating between the drain passage and the drain port is formed between the cover member and the center joint, and the angle sensor is disposed in the drain inlet chamber. It is characterized by the fact that Effect of the Invention

[0008] According to the present invention, the angle sensor is positioned between the center joint and the cover member provided on the upper end side of the center joint, so that the cover member can protect the angle sensor from external forces such as falling rocks and dust. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a left side view showing a hydraulic excavator according to a first embodiment of the present invention, as viewed from the left side. [Diagram 2] FIG. 2 is a vertical cross-sectional view showing a center joint, an angle sensor, a cover member, etc. according to the first embodiment. [Diagram 3] 3 is an enlarged cross-sectional view of a main part such as a cover member in FIG. 2. [Figure 4] FIG. 11 is a vertical cross-sectional view showing a center joint, an angle sensor, a cover member, etc. according to a second embodiment. [Diagram 5] 5 is an enlarged cross-sectional view of a main part such as a cover member in FIG. 4. [Figure 6] FIG. 11 is a vertical cross-sectional view showing a center joint, an angle sensor, a cover member, etc. according to a third embodiment. [Figure 7] 7 is an enlarged cross-sectional view of a main part such as a cover member in FIG. 6. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The present invention belongs to a group of inventions including multiple inventions described below. Below, first to third embodiments of the group of inventions will be described as embodiments of the group of inventions. Of these, the first and second embodiments correspond to the inventions described in the claims by the applicant. Hereinafter, an embodiment of a construction machine according to the present invention will be described in detail with reference to the accompanying drawings, taking as an example a case where the construction machine is applied to a crawler-type hydraulic excavator. In the embodiment, the traveling direction of the hydraulic excavator is defined as the front-rear direction, and the direction perpendicular to the traveling direction is defined as the left-right direction.

[0011] 1 to 3 show a first embodiment of the present invention. A hydraulic excavator 1 as a construction machine includes a self-propelled crawler-type undercarriage 2, an upper rotating body 4 rotatably mounted on the undercarriage 2 via a slewing wheel 3, and a working device 5 mounted on the front of the upper rotating body 4 so as to be capable of being raised and lowered.

[0012] The lower traveling body 2 has a track center frame 2A that supports the upper rotating body 4, and track side frames 2B (only the left side is shown) arranged on both the left and right sides of the track center frame 2A. Idler wheels 2C are provided on the front sides of the left and right track side frames 2B, respectively. Drive wheels 2D are provided on the rear sides of the left and right track side frames 2B, respectively. Tracks 2E are wound around the idler wheels 2C and the drive wheels 2D.

[0013] A traveling hydraulic motor 2F is provided on each of the left and right drive wheels 2D. The traveling hydraulic motor 2F is connected to a hydraulic pump 10 via a control valve (not shown), a center joint 11, etc. The hydraulic pump 10 draws in hydraulic oil from a hydraulic oil tank (not shown) mounted on the upper rotating body 4, pressurizes it, and supplies it to the traveling hydraulic motor 2F via the center joint 11, etc. The traveling hydraulic motor 2F rotationally drives the drive wheels 2D, and the crawler 2E performs an orbital motion, causing the hydraulic excavator 1 (lower traveling body 2) to travel.

[0014] The slewing ring 3 is provided between the track center frame 2A of the lower running body 2 and the slewing frame 6 of the upper rotating body 4. The slewing ring 3 includes an inner ring with an internal gear provided on its inner circumference, and an outer ring (neither shown) rotatably attached to the outer circumference of the inner ring. The inner ring of the slewing ring 3 is attached to the track center frame 2A, and the outer ring of the slewing ring 3 is attached to the slewing frame 6. A slewing motor is attached to the slewing frame 6, and a pinion gear (neither shown) provided on the output shaft of the slewing motor meshes with the internal gear provided on the inner ring of the slewing ring 3. Therefore, the upper rotating body 4 can be rotated on the lower running body 2 by driving the slewing motor to rotate.

[0015] The working device 5 has a swing post 5A attached to the front end of the revolving frame 6 so as to be able to swing (swing) in the left-right direction, a boom 5B attached to the swing post 5A so as to be able to move up and down, an arm 5C attached to the tip of the boom 5B so as to be able to turn, and a bucket 5D attached to the tip of the arm 5C so as to be able to turn. The boom 5B, arm 5C, and bucket 5D are driven by a boom cylinder 5E, an arm cylinder 5F, and a bucket cylinder 5G, respectively. A swing cylinder (not shown) that swings the swing post 5A in the left-right direction is provided between the revolving frame 6 and the swing post 5A.

[0016] The upper rotating body 4 is configured to include a rotating frame 6, a cab 7 provided on the left side of the rotating frame 6, and a counterweight 8 attached to the rear side of the rotating frame 6. The cab 7 defines a driver's cab where the operator operates the hydraulic excavator 1, and the counterweight 8 maintains the weight balance with the work equipment 5. An engine 9 and a hydraulic pump 10 are provided side by side in the left-right direction in front of the counterweight 8, and the hydraulic pump 10 is driven by the engine 9. A hydraulic oil tank (not shown) is provided on the right side of the rotating frame 6, and the hydraulic oil tank stores hydraulic oil to be supplied to hydraulic actuators such as the traveling hydraulic motor 2F, the swing motor, and the hydraulic cylinders 5E, 5F, and 5G mounted on the hydraulic excavator 1.

[0017] The revolving frame 6 has a flat bottom plate 6A serving as a base, and the outer ring of the revolving ring 3 is attached to the underside of the bottom plate 6A. In addition, a body 12 that constitutes a center joint 11 is attached to the bottom plate 6A, located at the center of the revolving ring 3 (the revolving center of the upper revolving body 4).

[0018] The center joint 11 is located at the rotation center OO of the upper rotating body 4 and is provided between the upper rotating body 4 and the lower traveling body 2. The center joint 11 circulates pressure oil between a hydraulic pump 10 and a hydraulic oil tank provided on the upper rotating body 4, and a traveling hydraulic motor 2F provided on the lower traveling body 2. As shown in Figures 2 and 3, the center joint 11 includes a cylindrical body 12 attached to the upper rotating body 4, and a cylindrical spindle 17 attached to the lower traveling body 2 and rotatably fitted into the inner periphery of the body 12.

[0019] The body 12 is attached to the revolving frame 6 of the upper revolving body 4 by using bolts (not shown). The body 12 extends in the vertical direction with its center line coinciding with the center of rotation of the upper revolving body 4. Four annular passages 13, 14, 15, 16 are formed on the inner peripheral surface 12A of the body 12 at appropriate intervals in the axial direction (vertical direction). These four annular passages 13 to 16 are each made of a full circumferential groove formed around the entire circumference of the inner peripheral surface of the body 12. One end of each of the four annular passages 13A, 14A, 15A, 16A extending in the radial direction of the body 12 is connected to each of the four annular passages 13 to 16. The other ends of these four body side connection ports 13A to 16A open on the outer peripheral surface of the body 12, and are connected to a hydraulic source side hydraulic hose 26 described later. An upper end 12B side of the body 12 constitutes an upper cylindrical portion 12C, and a lower opening 22A of a cover member 22, which will be described later, is fitted into the upper cylindrical portion 12C.

[0020] The spindle 17 is attached to the track center frame 2A of the lower traveling body 2 via a plate-shaped stopper (not shown) fixed to the lower end surface. The spindle 17 extends in the vertical direction with its center line coinciding with the center of rotation of the upper rotating body 4, and is rotatably fitted to the inner periphery of the body 12. The spindle 17 has a fitting portion 17A that fits into the inner periphery 12A of the body 12, a small diameter cylindrical portion 17B that protrudes upward from the upper end 12B of the body 12, and a lower protruding portion 17C that protrudes downward from the lower end 12D of the body 12. The outer diameter dimension of the small diameter cylindrical portion 17B is smaller than that of the fitting portion 17A, and the boundary portion between the fitting portion 17A and the small diameter cylindrical portion 17B is an annular flat surface 17D. The outer diameter of the lower protrusion 17C is larger than that of the fitting portion 17A, and a lower locking portion 17E that sets the lower limit position of the body 12 relative to the spindle 17 is provided at the boundary between the fitting portion 17A and the lower protrusion 17C.

[0021] Four recessed grooves 17G are formed annularly around the entire circumference of the outer circumferential surface 17F of the fitting portion 17A of the spindle 17. These four recessed grooves 17G are disposed at positions corresponding to the four annular passages 13-16 of the body 12, respectively, and form part of these annular passages 13-16.

[0022] The spindle 17 has four oil passages 18 extending in the axial direction formed at angular intervals of 90 degrees in the circumferential direction (only one is shown). A total of four oil passages 18 are provided to supply and discharge pressure oil to the left and right traveling hydraulic motors 2F provided on the lower traveling body 2. These four oil passages 18 are connected respectively to the annular passages 13, 14, 15, and 16, and therefore have different axial length dimensions (the oil passage 18 in FIG. 2 is connected to the annular passage 14).

[0023] Two spindle-side connection ports 18A are formed at the lower ends of the four oil passages 18, each opening into the outer circumferential surface of the lower protrusion 17C of the spindle 17. A motor-side hydraulic hose 27, which will be described later, is connected to the spindle-side connection port 18A. As a result, the body-side connection ports 13A-16A of the body 12 communicate with the spindle-side connection port 18A via the annular passages 13-16 and the oil passage 18 of the spindle 17. Therefore, the hydraulic source-side hydraulic hose 26 and the motor-side hydraulic hose 27 always communicate with each other via the center joint 11, and pressure oil can be circulated between the hydraulic pump 10 and the hydraulic oil tank (hydraulic source) and the traveling hydraulic motor 2F even when the upper rotating body 4 rotates on the lower traveling body 2.

[0024] Five annular seals 19 are provided between the inner peripheral surface 12A of the body 12 and the outer peripheral surface 17F of the fitting portion 17A of the spindle 17. These five annular seals 19 are disposed at positions that sandwich the four annular passages 13, 14, 15, and 16 formed on the inner peripheral surface 12A of the body 12 in the axial direction, respectively, and provide sealing between the four annular passages 13, 14, 15, and 16.

[0025] The spindle 17 is also provided with one drain passage 20 that extends in the axial direction in a location different from the four oil passages 18. The drain passage 20 returns drain oil from the traveling hydraulic motor 2F to the hydraulic oil tank. The lower end of the drain passage 20 is a spindle-side drain port 20A that opens into the outer circumferential surface of the lower protrusion 17C of the spindle 17, and a motor-side drain hose 29, which will be described later, is connected to this spindle-side drain port 20A. The upper end of the drain passage 20 opens into the flat surface 17D of the spindle 17, and communicates with a drain inlet chamber 25, which will be described later.

[0026] The stopper 21 is attached to the flat surface 17D of the spindle 17 by using bolts or the like (not shown). The stopper 21 is formed of an annular plate having an outer diameter larger than that of the fitting portion 17A of the spindle 17 and an inner diameter larger than that of the small diameter cylindrical portion 17B. The stopper 21 abuts against the upper end 12B of the body 12 to prevent the body 12 from being pulled out upward, and the upper end 12B of the body 12 is disposed on the same plane as the flat surface 17D of the spindle 17. As a result, the body 12 is positioned in the axial direction of the spindle 17 by the lower locking portion 17E of the spindle 17 and the stopper 21. A through hole 21A is formed in the stopper 21 at a portion corresponding to the upper end of the drain passage 20, penetrating in the plate thickness direction.

[0027] The cover member 22 is provided on the upper end side of the center joint 11 and covers the fitting portion between the body 12 and the spindle 17 from above. As shown in FIG. 3, the cover member 22 has a lower opening 22A that fits into the upper cylindrical portion 12C of the body 12 and an upper opening 22B that fits into the small diameter cylindrical portion 17B of the spindle 17. An annular lower seal member 23A is provided at the fitting portion between the lower opening 22A and the upper cylindrical portion 12C of the body 12. An annular upper seal member 23B and an annular dust seal 24 are provided at the fitting portion between the upper opening 22B and the small diameter cylindrical portion 17B of the spindle 17. In addition, a cover side drain port 22C is formed in the cover member 22 so as to be perpendicular to the axial direction of the spindle 17. One end of the cover side drain port 22C opens to the drain inlet chamber 25, and the other end of the cover side drain port 22C opens to the outer circumferential surface of the cover member 22. A tank side drain hose 28, which will be described later, is connected to the cover side drain port 22C.

[0028] The drain inlet chamber 25 is formed between the cover member 22 and the center joint 11, and communicates between the upper end of the drain passage 20 and the cover side drain port 22C of the cover member 22. Specifically, the drain inlet chamber 25 is formed as an annular chamber surrounded by the upper end 12B of the body 12, the flat surface 17D of the fitting portion 17A constituting the spindle 17, the outer circumferential surface of the small diameter cylindrical portion 17B, and the cover member 22, and is sealed by the lower seal member 23A, the upper seal member 23B, and the annular seal 19. Therefore, the drain oil from the traveling hydraulic motor 2F flows into the drain inlet chamber 25 through the motor side drain hose 29, the drain passage 20, the through hole 21A of the stopper 21, etc., and is returned to the hydraulic oil tank through the cover side drain port 22C of the cover member 22, the tank side drain hose 28, etc.

[0029] The hydraulic source side hydraulic hoses 26 connect the hydraulic source provided in the upper rotating body 4, i.e., the hydraulic pump 10 and the hydraulic oil tank, to the center joint 11. A total of four hydraulic source side hydraulic hoses 26 are provided, two for each of the two (left and right) traveling hydraulic motors 2F, for supplying and discharging pressure oil thereto. Two of the four hydraulic source side hydraulic hoses 26 are connected at one end to the hydraulic pump 10 via a control valve (not shown), and at the other end to any two of the body side connection ports 13A to 16A of the body 12. The other two of the four hydraulic source side hydraulic hoses 26 are connected at one end to a hydraulic oil tank via a control valve (not shown), and at the other end to the remaining two of the body side connection ports 13A to 16A of the body 12.

[0030] The motor-side hydraulic hoses 27 connect between the left and right traveling hydraulic motors 2F provided on the undercarriage 2 and the center joint 11. In order to supply and discharge a large amount of pressure oil to the two (left and right) traveling hydraulic motors 2F, a total of eight motor-side hydraulic hoses 27 are provided, two for each oil passage 18 (only two are shown). One end of each of the eight motor-side hydraulic hoses 27 is connected to the spindle-side connection port 18A of the oil passage 18, and the other end is connected to the traveling hydraulic motor 2F.

[0031] The tank side drain hose 28 connects the hydraulic oil tank and the cover side drain port 22C of the cover member 22. One end of the tank side drain hose 28 is connected to the hydraulic oil tank, and the other end of the tank side drain hose 28 is connected to the cover side drain port 22C of the cover member 22. The motor side drain hose 29 connects the left and right traveling hydraulic motors 2F and the center joint 11. One end of the motor side drain hose 29 is connected to the traveling hydraulic motor 2F, and the other end of the motor side drain hose 29 is connected to the spindle side drain port 20A of the drain passage 20 formed in the spindle 17.

[0032] The angle sensor 30 is located in the drain inflow chamber 25 and provided between the cover member 22 and the spindle 17. The angle sensor 30 includes a stator 30A attached to the cover member 22 and a rotor 30B attached to the spindle 17 and rotatable relative to the stator 30A, and has oil resistance. The stator 30A is formed in an annular shape surrounding the small diameter cylindrical portion 17B of the spindle 17 from the outer periphery, and is attached to the cover member 22 using bolts or the like. The rotor 30B is also formed in an annular shape surrounding the small diameter cylindrical portion 17B of the spindle 17 from the outer periphery, and is attached to the spindle 17 or the stopper 21 with an appropriate gap maintained between the rotor 30B and the stator 30A.

[0033] The stator 30A of the angle sensor 30 includes a mechanism for outputting angle information as an electric signal, and is electrically connected to a controller 31 mounted on the upper rotating body 4 via a harness 30C. When the upper rotating body 4 rotates relative to the lower traveling body 2, the angle sensor 30 constantly detects the rotation angle of the upper rotating body 4, and outputs a detection signal (electrical signal) according to the rotation angle to the controller 31. The cover member 22 is formed with a harness insertion hole 22D that opens into the drain inlet chamber 25, and the harness 30C is led out to the outside through the harness insertion hole 22D. Between the cover member 22 and the stator 30A, an annular seal 22E is provided so as to surround the periphery of the harness insertion hole 22D, and the seal 22E seals the harness insertion hole 22D from the drain inlet chamber 25.

[0034] The hydraulic excavator 1 according to the first embodiment has the configuration described above. Next, the operation of the hydraulic excavator 1 will be described.

[0035] When performing excavation work or the like using the hydraulic excavator 1, the operator gets into the cab 7, starts the engine 9, and drives the hydraulic excavator 1 to the work site by operating a driving control lever (not shown) located inside the cab 7.

[0036] At this time, the hydraulic pump 10 is driven by the engine 9, pressurizes the hydraulic oil sucked from the hydraulic oil tank, and discharges the pressurized oil toward various hydraulic actuators mounted on the hydraulic excavator 1. The pressurized oil discharged from the hydraulic pump 10 is supplied to the left and right traveling hydraulic motors 2F via a control valve, a center joint 11, etc. in response to the operation of the operating lever for traveling.

[0037] Specifically, the pressure oil discharged from the hydraulic pump 10 is supplied to the traveling hydraulic motor 2F from the control valve through the hydraulic source side hydraulic hose 26, the annular passages 13-16 of the body 12, the oil passage 18 of the spindle 17, the motor side hydraulic hose 27, etc. On the other hand, the pressure oil discharged from the traveling hydraulic motor 2F returns to the hydraulic oil tank through the motor side hydraulic hose 27, the oil passage 18 of the spindle 17, the annular passages 13-16 of the body 12, the hydraulic source side hydraulic hose 26, the control valve, etc. This causes the traveling hydraulic motor 2F to rotate, causing the lower traveling body 2 to travel.

[0038] Here, a part of the pressure oil supplied to the traveling hydraulic motor 2F lubricates the sliding parts of the traveling hydraulic motor 2F, and then becomes drain oil and is returned to the hydraulic oil tank. Specifically, the drain oil flowing out from the traveling hydraulic motor 2F is returned to the hydraulic oil tank through the motor side drain hose 29, the drain passage 20 of the spindle 17, the drain inlet chamber 25, the tank side drain hose 28, etc.

[0039] On the other hand, when performing work such as excavating earth and sand, the operator in the cab 7 controls the operation of the working device 5 while rotating the upper rotating body 4 by operating a work operation lever (not shown).

[0040] When the upper rotating body 4 is rotated on the lower traveling body 2, the angle sensor 30 detects the rotation angle of the upper rotating body 4 relative to the lower traveling body 2 and outputs a detection signal corresponding to this rotation angle to the controller 31 via the harness 30C. As a result, the controller 31 calculates the rotation angle of the upper rotating body 4 based on the detection signal from the angle sensor 30 and displays the rotation angle on a monitor (not shown) in the cab 7, for example. Therefore, the operator can accurately control the rotation operation of the upper rotating body 4 with the operating lever by visually checking the rotation angle displayed on the monitor.

[0041] According to the first embodiment, a cover member 22 is provided on the upper end side of the center joint 11 to cover from above the fitting portion between the body 12 and the spindle 17, i.e., the fitting portion between the inner circumferential surface 12A of the body 12 and the outer circumferential surface 17F of the fitting portion 17A of the spindle 17. The angle sensor 30 is disposed in a drain inlet chamber 25 formed between the cover member 22 and the center joint 11.

[0042] As a result, even if rocks, dust, etc. fall from the working equipment 5 toward the center joint 11 during excavation work by the hydraulic excavator 1, the cover member 22 can prevent the falling rocks, dust, etc. from colliding with the angle sensor 30. In this case, the body 12, spindle 17, and cover member 22 that constitute the center joint 11 are designed to have a strength sufficient to withstand the pressure of the pressurized oil flowing through the center joint 11. For this reason, even if a falling rock collides with the cover member 22, etc., the external force caused by this impact will not reach the angle sensor 30.

[0043] Furthermore, the gap between the cover member 22 and the center joint 11 is sealed by a lower seal member 23A, an upper seal member 23B, and a dust seal 24, and the angle sensor 30 is sealed against muddy water, rainwater, etc. As a result, failure of the angle sensor 30, which is a precision device, can be prevented and its durability can be increased, and the rotation operation of the upper rotating body 4 can be accurately controlled based on the detection signal from the angle sensor 30 over a long period of time.

[0044] Furthermore, by arranging the angle sensor 30 on the upper end side of the center joint 11, it is possible to more easily connect the controller 31 provided on the upper rotating body 4 and the angle sensor 30 via the harness 30C, compared to, for example, the case where the angle sensor is arranged on the lower end side of the center joint. Moreover, since the length of the harness 30C can be made as short as possible, the workability when routing the harness 30C inside the upper rotating body 4 can be improved.

[0045] Thus, the hydraulic excavator 1 according to the first embodiment comprises a self-propelled lower traveling body 2 provided with a traveling hydraulic motor 2F, an upper rotating body 4 provided rotatably on the lower traveling body 2, a hydraulic pump 10 provided on the upper rotating body 4 and discharging hydraulic oil in a hydraulic oil tank mounted on the upper rotating body 4 as pressurized oil, a center joint 11 located at the rotation center of the upper rotating body 4 and provided between the upper rotating body 4 and the lower traveling body 2, and allowing pressurized oil to circulate between the hydraulic pump 10 and the hydraulic oil tank, and the traveling hydraulic motor 2F, and an angle sensor 30 that detects the rotation angle of the upper rotating body 4 relative to the lower traveling body 2, and the center joint 11 is configured to include a cylindrical body 12 attached to the upper rotating body 4, and a spindle 17 attached to the lower traveling body 2 and rotatably fitted into the inner periphery of the body 12. A cover member 22 is provided on the upper end side of the center joint 11 to cover the fitting portion between the body 12 and the spindle 17 from above, and the angle sensor 30 is provided between the cover member 22 and the spindle 17.

[0046] According to this configuration, the cover member 22 can prevent falling rocks, dust, and the like from colliding with the angle sensor 30 during excavation work by the hydraulic excavator 1, and the angle sensor 30 can be provided in the center joint 11 while being protected from external forces. As a result, failure of the angle sensor 30, which is a precision device, can be prevented, and the rotation operation of the upper rotating body 4 can be accurately controlled based on the detection signal from the angle sensor 30.

[0047] In the embodiment, the spindle 17 is provided with a drain passage 20 for returning drain oil from the traveling hydraulic motor 2F to the hydraulic oil tank, the cover member 22 is provided with a cover-side drain port 22C to which a tank-side drain hose 28 for returning the drain oil to the hydraulic oil tank is connected, and a drain inlet chamber 25 for communicating between the drain passage 20 and the cover-side drain port 22C is formed between the cover member 22 and the center joint 11, and the angle sensor 30 is disposed in the drain inlet chamber 25. According to this configuration, the angle sensor 30 can be disposed by utilizing the drain inlet chamber 25 formed between the cover member 22 and the center joint 11. Therefore, the center joint 11 and the angle sensor 30 can be housed compactly in the upper rotating body 4.

[0048] In the embodiment, a small diameter cylindrical portion 17B is provided at the upper end of the spindle 17, and the angle sensor 30 has an annular stator 30A and an annular rotor 30B surrounding the small diameter cylindrical portion 17B, the stator 30A being attached to the cover member 22 side, and the rotor 30B being attached to the spindle 17 side. According to this configuration, the stator 30A and the rotor 30B of the angle sensor 30 can be efficiently arranged in the narrow drain inflow chamber 25 formed between the upper end of the spindle 17 and the cover member 22.

[0049] Next, Figures 4 and 5 show a second embodiment of the present invention. The feature of this embodiment is that a sealed space is formed between the spindle and the cover member by a seal member, and an angle sensor is disposed in this sealed space. In this embodiment, the same components as those in the first embodiment are given the same reference numerals, and their description will be omitted.

[0050] The center joint 41 according to the second embodiment includes a body 12 and a spindle 42, and a cover member 45 is provided on the upper end side of the center joint 41 to cover from above the fitting portion between the body 12 and the spindle 42. However, the shapes of the spindle 42 and the cover member 45 are different from those of the spindle 17 and the cover member 22 according to the first embodiment.

[0051] The spindle 42 is rotatably fitted to the inner periphery of the body 12. The spindle 42 has a fitting portion 42A that fits to the inner periphery 12A of the body 12, a medium diameter cylindrical portion 42B that protrudes upward from the upper end 12B of the body 12, a small diameter cylindrical portion 42C that protrudes upward from the medium diameter cylindrical portion 42B, and a lower protruding portion 42D that protrudes downward from the lower end 12D of the body 12. The outer diameter dimension of the medium diameter cylindrical portion 42B is smaller than that of the fitting portion 42A and larger than that of the small diameter cylindrical portion 42C. The boundary between the fitting portion 42A and the medium diameter cylindrical portion 42B is an annular lower flat surface 42E, and the boundary between the medium diameter cylindrical portion 42B and the small diameter cylindrical portion 42C is an annular upper flat surface 42F. The outer diameter of the lower protrusion 42D is larger than that of the fitting portion 42A, and a lower locking portion 42G that sets the lower limit position of the body 12 relative to the spindle 42 is provided at the boundary between the fitting portion 42A and the lower protrusion 42D.

[0052] Four recessed grooves 42J are formed in an annular shape on the outer circumferential surface 42H of the fitting portion 42A of the spindle 42, and these four recessed grooves 42J respectively constitute a part of the four annular passages 13-16 of the body 12. A stopper 43 is attached to the lower flat surface 42E of the spindle 42 using a bolt or the like. The stopper 43 abuts against the upper end 12B of the body 12 to prevent the body 12 from being pulled out upward, and the upper end 12B of the body 12 is disposed on the same plane as the lower flat surface 42E of the spindle 42. The body 12 is positioned in the axial direction of the spindle 42 by the lower locking portion 42G of the spindle 42 and the stopper 43.

[0053] The spindle 42 is provided with four axially extending oil passages 18 spaced at 90 degree intervals in the circumferential direction (only one oil passage is shown). Two spindle-side connection ports 18A are formed at the lower ends of the four oil passages 18, each opening into the outer circumferential surface of the lower protrusion 42D of the spindle 42. The spindle 42 is also provided with one drain passage 44 extending in the axial direction at a location different from the four oil passages 18. The lower end of the drain passage 44 is a spindle-side drain port 44A that opens into the outer circumferential surface of the lower protrusion 42D of the spindle 42. The upper end of the drain passage 44 opens into the outer circumferential surface of the medium diameter cylindrical portion 42B of the spindle 42, and communicates with a drain inlet chamber 47.

[0054] The cover member 45 is provided on the upper end side of the center joint 41 and covers the fitting portion between the body 12 and the spindle 42 from above. The cover member 45 has a lower opening 45A that fits into the upper cylindrical portion 12C of the body 12, an intermediate opening 45B that fits into the medium diameter cylindrical portion 42B of the spindle 42, and an upper opening 45C that fits into the small diameter cylindrical portion 42C of the spindle 42. An annular lower seal member 46A is provided at the fitting portion between the lower opening 45A and the upper cylindrical portion 12C of the body 12, and an annular upper seal member 46B is provided at the fitting portion between the intermediate opening 45B and the medium diameter cylindrical portion 42B of the spindle 42. An annular dust seal 46C is provided at the fitting portion between the upper opening 45C and the small diameter cylindrical portion 42C of the spindle 42. In addition, a cover side drain port 45D perpendicular to the axial direction of the spindle 42 is formed in the cover member 45. One end of the cover side drain port 45D opens to the drain inlet chamber 47, and the other end of the cover side drain port 45D opens to the outer circumferential surface of the cover member 45.

[0055] The drain inlet chamber 47 is formed between the cover member 45 and the center joint 41, and communicates between the upper end of the drain passage 44 and the cover-side drain port 45D. Specifically, the drain inlet chamber 47 is formed as an annular chamber surrounded by the upper end 12B of the body 12, the lower flat surface 42E of the fitting portion 42A constituting the spindle 42, the outer circumferential surface of the medium diameter cylindrical portion 42B, and the cover member 45, and is sealed by the lower seal member 46A, the upper seal member 46B, and the annular seal 19. Drain oil from the traveling hydraulic motor 2F flows into the drain inlet chamber 47 through the motor-side drain hose 29, the drain passage 44, etc., and is returned to the hydraulic oil tank through the cover-side drain port 45D of the cover member 45 and the tank-side drain hose 28, etc.

[0056] The sealed space 48 is located above the drain inlet chamber 47 and is formed between the cover member 45 and the spindle 42. Specifically, the sealed space 48 is formed as an annular space surrounded by the upper flat surface 42F of the spindle 42, the outer circumferential surface of the small diameter cylindrical portion 42C, and the cover member 45. The sealed space 48 is liquid-tightly sealed from the drain inlet chamber 47 by the upper seal member 46B, and is isolated from the hydraulic oil (pressurized oil) and drain oil flowing through the center joint 41. The sealed space 48 is also sealed against dust, rainwater, and the like by the dust seal 46C.

[0057] Angle sensor 49 is disposed in sealed space 48. Similar to angle sensor 30 used in the first embodiment, angle sensor 49 includes an annular stator 49A and rotor 49B that surround small diameter cylindrical portion 42C of spindle 42. However, angle sensor 49 is not oil resistant since it is disposed in sealed space 48 isolated from hydraulic oil and drain oil.

[0058] The stator 49A of the angle sensor 49 is electrically connected to the controller 31 via a harness 49C. A harness insertion hole 45E is formed in the cover member 45, and the harness 49C is led out to the outside through the harness insertion hole 45E. In this case, since the angle sensor 49 is disposed in the sealed space 48, the hydraulic oil and drain oil do not leak out of the cover member 45 through the harness insertion hole 45E, and it is not necessary to provide a groove for attaching a seal around the harness insertion hole 45E.

[0059] The hydraulic excavator according to the second embodiment is equipped with the center joint 41 as described above, and has the same basic effect as the first embodiment in that the cover member 45 can prevent falling rocks, dust, and the like that fall toward the center joint 41 from colliding with the angle sensor 49. However, in the second embodiment, an enclosed space 48 that is isolated from hydraulic oil and drain oil is formed between the spindle 42 of the center joint 41 and the cover member 45, and the angle sensor 49 is disposed within this enclosed space 48.

[0060] This eliminates the need to make angle sensor 49 expensive and oil-resistant, thereby reducing the cost associated with angle sensor 49. Also, it eliminates the need to provide a seal and a groove for attaching the seal around harness insertion hole 45E formed in cover member 45 for inserting harness 49C of angle sensor 49, thereby reducing the cost associated with cover member 45.

[0061] Next, Figures 6 and 7 show a third embodiment of the present invention. The feature of this embodiment is that an enclosed space is formed between the lower end of the center joint and the cover member, and an angle sensor is disposed in this enclosed space. In this embodiment, the same components as those in the first embodiment are given the same reference numerals, and their explanation will be omitted.

[0062] The center joint 51 according to the third embodiment includes a cylindrical body 52 attached to the lower traveling body 2, and a columnar spindle 57 attached to the upper rotating body 4 and rotatably fitted into the inner periphery of the body 52. ​​The body 52 and the spindle 57 extend in the vertical direction with their respective centerlines coinciding with the center of rotation of the upper rotating body 4.

[0063] The body 52 is formed in a stepped cylindrical shape with the outer diameter dimension at the upper end being smaller. Four annular passages 53, 54, 55, 56 are formed in the inner peripheral surface 52A of the body 52 at appropriate intervals in the axial direction. One end of body side connection ports 53A, 54A, 55A, 56A extending in the radial direction of the body 52 is connected to each of the four annular passages 53 to 56. The other ends of the four body side connection ports 53A to 56A open to the outer peripheral surface of the body 52 and are connected to the motor side hydraulic hose 27. A stopper accommodating portion 52B having an inner diameter dimension larger than that of the inner peripheral surface 52A is formed at the lower end on the inner peripheral side of the body 52.

[0064] The spindle 57 is rotatably fitted to the inner periphery of the body 52. ​​The spindle 57 has a fitting portion 57A that fits to the inner periphery 52A of the body 52, an upper protrusion 57B that protrudes upward from the upper end 52C of the body 52, and a lower protrusion 57C that protrudes downward from the lower end 52D of the body 52. ​​The outer diameter of the upper protrusion 57B is larger than that of the fitting portion 57A, and the outer diameter of the lower protrusion 57C is smaller than that of the fitting portion 57A. A step 57D is provided at the boundary between the fitting portion 57A and the lower protrusion 57C. A sensor mounting hole 57E consisting of a circular recess concentric with the spindle 57 is formed at the lower end of the lower protrusion 57C.

[0065] The spindle 57 has four oil passages 58 extending in the axial direction formed at angular intervals of 90 degrees in the circumferential direction (only one is shown). A total of four oil passages 58 are provided to supply and discharge pressure oil to the left and right traveling hydraulic motors 2F provided on the lower traveling body 2. These four oil passages 58 are each connected to the annular passages 53, 54, 55, 56 (the oil passage 58 in FIG. 6 is connected to the annular passage 56).

[0066] A spindle-side connection port 58A is formed at the upper end of each of the four oil passages 58, and opens into the upper end surface of the spindle 57 (upper protrusion 57B). The hydraulic pressure-source-side hydraulic hose 26 is connected to the spindle-side connection port 58A. As a result, the body-side connection ports 53A-56A of the body 52 communicate with the spindle-side connection port 58A via the annular passages 53-56 and the oil passage 58 of the spindle 57. Therefore, the hydraulic pressure-source-side hydraulic hose 26 and the motor-side hydraulic hose 27 are always in communication with each other via the center joint 51.

[0067] A plurality of annular seals 59 are provided between the inner peripheral surface 52A of the body 52 and the outer peripheral surface of the fitting portion 57A of the spindle 57. Five of the plurality of annular seals 59 are disposed at positions sandwiching the annular passages 53, 54, 55, and 56 of the body 52 in the axial direction, respectively, and provide a seal between the four annular passages 53, 54, 55, and 56. In addition, a dust seal 60 is provided between the upper end side of the inner peripheral surface 52A of the body 52 and the outer peripheral surface of the fitting portion 57A of the spindle 57.

[0068] The spindle 57 is provided with a central hole 61 extending in the axial direction and a drain passage 62. The central hole 61 extends in the axial direction through the center of the spindle 57, and the lower end of the central hole 61 opens into a sensor mounting hole 57E of the spindle 57. A horizontal hole 61A extending in the radial direction is provided on the upper end side of the central hole 61, and the tip of the horizontal hole 61A opens into the outer circumferential surface of the upper protrusion 57B. A harness 69C of the angle sensor 69 is inserted into the central hole 61.

[0069] The drain passage 62 extends in the axial direction in a position different from the central hole 61 and the four oil passages 58. The drain passage 62 returns drain oil from the traveling hydraulic motor 2F to the hydraulic oil tank. The lower end of the drain passage 62 opens into the outer peripheral surface of the lower protrusion 57C of the spindle 57 and communicates with an annular drain passage 67, which will be described later. The upper end of the drain passage 62 is a spindle-side drain port 62A that opens into the outer peripheral surface of the upper protrusion 57B of the spindle 57, and the tank-side drain hose 28 is connected to this spindle-side drain port 62A.

[0070] The cover member 63 is provided on the lower end side of the center joint 51 and covers the fitting portion between the body 52 and the spindle 57 from below. The cover member 63 has a cylindrical portion 63A attached to the lower end 52D of the body 52 and a bottom portion 63B closing the lower side of the cylindrical portion 63A. On the inner peripheral side of the cylindrical portion 63A, a small diameter opening portion 63C located on the bottom portion 63B side and a large diameter opening portion 63D expanding in diameter upward from the small diameter opening portion 63C in a truncated cone shape are formed. On the outer peripheral surface of the cylindrical portion 63A, a cover side drain port 63E is formed, and the cover side drain port 63E is connected to the large diameter opening portion 63D.

[0071] The cover member 63 is attached to the body 52 using bolts (not shown) with the upper end of the cylindrical portion 63A abutting against the lower end 52D of the body 52. ​​With the cover member 63 attached to the body 52, the small diameter opening 63C of the cover member 63 fits into the outer circumferential surface of the lower protrusion 57C of the spindle 57. An annular seal member 64 is provided at the fitting portion between the small diameter opening 63C of the cover member 63 and the lower protrusion 57C of the spindle 57.

[0072] The stopper 65 is provided between the lower end side of the center joint 51 and the cover member 63. The stopper 65 is formed of an annular plate having an outer diameter larger than that of the fitting portion 57A of the spindle 57 and an inner diameter larger than that of the lower protrusion 57C. The inner peripheral side of the stopper 65 is disposed between the step portion 57D of the spindle 57 and a retaining ring 66 attached to the outer peripheral surface of the lower protrusion 57C. The outer peripheral side of the stopper 65 is disposed between the stopper accommodating portion 52B of the body 52 and the upper end surface of the cylindrical portion 63A of the cover member 63. As a result, the stopper 65 positions the spindle 57 with respect to the body 52 in the axial direction.

[0073] The annular drain passage 67 is formed between the cover member 63 and the center joint 51, and connects the lower end of the drain passage 62 to a cover-side drain port 63E of the cover member 63. Specifically, the annular drain passage 67 is formed as an annular passage surrounded by the outer circumferential surface of the lower protrusion 57C of the spindle 57, the stopper 65, and the cover member 63. Therefore, drain oil from the traveling hydraulic motor 2F flows into the annular drain passage 67 through the motor-side drain hose 29, the cover-side drain port 63E, etc., and is returned to the hydraulic oil tank through the drain passage 62 of the spindle 57, the spindle-side drain port 62A, the tank-side drain hose 28, etc.

[0074] The sealed space 68 is located below the annular drain passage 67 and is formed between the cover member 63 and the spindle 57. Specifically, the sealed space 68 is formed as a space surrounded by the lower end surface of the lower protrusion 57C of the spindle 57, the sensor mounting hole 57E, and the inner circumferential surface of the cylindrical portion 63A and the bottom portion 63B of the cover member 63. The sealed space 68 is liquid-tight sealed from the annular drain passage 67 by the seal member 64, and the center hole 61 communicating with the sealed space 68 via the sensor mounting hole 57E is also liquid-tight sealed from the annular drain passage 67. As a result, the sealed space 68 and the center hole 61 are isolated from the hydraulic oil (pressurized oil) and drain oil flowing through the center joint 51.

[0075] The angle sensor 69 is disposed in the sealed space 68. The angle sensor 69 includes a stator 69A disposed in the sensor mounting hole 57E of the spindle 57, and a rotor 69B attached to the bottom 63B of the cover member 63 using a bolt 70. The stator 69A of the angle sensor 69 is electrically connected to the controller 31 via a harness 69C that passes through the center hole 61 and is led out to the outside of the spindle 57.

[0076] The hydraulic excavator according to the third embodiment has the center joint 51 as described above. For example, when the hydraulic excavator travels on rough terrain, even if soil or the like is kicked up by the crawler 2E and scattered toward the center joint 51, the cover member 63 can prevent the soil or the like from colliding with the angle sensor 69.

[0077] Furthermore, in the third embodiment, an enclosed space 68 isolated from hydraulic oil and drain oil is formed between the spindle 57 and the cover member 63 of the center joint 51, and an angle sensor 69 is disposed in this enclosed space 68. Also, a central hole 61 isolated from hydraulic oil and drain oil is formed in the center of the spindle 57, and a harness 69C of the angle sensor 69 is disposed in this central hole 61. As a result, it is not necessary to make the angle sensor 69 and the harness 69C of expensive oil-resistant specifications, and the cost associated with the angle sensor 69 can be reduced.

[0078] In the embodiment, a hydraulic excavator equipped with a crawler-type lower traveling body 2 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 construction machines such as wheel-type hydraulic excavators and hydraulic cranes. [Explanation of symbols]

[0079] 1. Hydraulic excavator (construction machinery) 2 Undercarriage 2F Hydraulic motor for travel (hydraulic motor) 4. Upper rotating body 10 Hydraulic pump 11,41,51 Center joint 12,52 Body 17,42,57 Spindle 20,44,62 Drain passage 22,45,63 Cover member 22C,45D Cover side drain port 23A, 46A Lower seal member (seal member) 23B, 46B Upper seal member (seal member) 25,47 Drain inlet chamber 28 Tank side drain hose 30,49,69 Angle Sensor 30A, 49A, 69A Stator 30B, 49B, 69B rotor 48,68 Closed space 61 Center hole 64 Sealing material 69C Harness

Claims

1. a self-propelled lower traveling body provided with a hydraulic motor for traveling; An upper rotating body rotatably provided on the lower traveling body; a hydraulic pump provided on the upper rotating body and configured to discharge hydraulic oil in a hydraulic oil tank mounted on the upper rotating body as pressurized oil; a center joint that is located at a rotation center of the upper rotating body and is provided between the upper rotating body and the lower traveling body, and that allows pressure oil to flow between the hydraulic pump, the hydraulic oil tank, and the hydraulic motor; an angle sensor for detecting a rotation angle of the upper rotating body relative to the lower traveling body, In a construction machine comprising the center joint including a cylindrical body attached to the upper rotating body and a spindle attached to the lower traveling body and rotatably fitted to an inner periphery of the body, a cover member is provided on the upper end side of the center joint to cover from above a fitting portion between the body and the spindle, the angle sensor is disposed between the cover member and the spindle, The spindle is provided with a drain passage for returning drain oil from the hydraulic motor to the hydraulic oil tank, The cover member is provided with a drain port to which a drain hose for returning drain oil to the hydraulic oil tank is connected, A drain inlet chamber is formed between the cover member and the center joint, which connects the drain passage and the drain port, A construction machine characterized in that the angle sensor is disposed in the drain inlet chamber.

2. A self-propelled lower traveling body provided with a hydraulic motor for traveling; An upper rotating body rotatably provided on the lower traveling body; a hydraulic pump provided on the upper rotating body and configured to discharge hydraulic oil in a hydraulic oil tank mounted on the upper rotating body as pressurized oil; a center joint that is located at a rotation center of the upper rotating body and is provided between the upper rotating body and the lower traveling body, and that allows pressure oil to flow between the hydraulic pump, the hydraulic oil tank, and the hydraulic motor; an angle sensor for detecting a rotation angle of the upper rotating body relative to the lower traveling body, In a construction machine comprising the center joint including a cylindrical body attached to the upper rotating body and a spindle attached to the lower traveling body and rotatably fitted to an inner periphery of the body, a cover member is provided on the upper end side of the center joint to cover from above a fitting portion between the body and the spindle, the angle sensor is disposed between the cover member and the spindle, The upper end of the spindle is provided with a small diameter cylindrical portion, the angle sensor has an annular stator and an annular rotor surrounding the cylindrical portion, A construction machine characterized in that the stator is attached to the cover member side, and the rotor is attached to the spindle side.

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