Construction machine

Abstract

To provide a construction machine capable of stably monitoring a pivot bearing.SOLUTION: An outer ring 25 of a pivot bearing 22 is attached to an upper rotating body 16 side. An inner ring 23 of the pivot bearing 22 is attached to a lower running body 2 side. An outer ring side inclination sensor 41 that detects the inclination of the outer ring 25 is attached to the outer ring 25, and an inner ring side inclination sensor 42 that detects the inclination of the inner ring 23 is attached to the inner ring 23.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to construction machines such as hydraulic excavators. [Background technology]

[0002] For example, if flaking occurs on the raceway surface (orbital surface) of a slewing bearing installed in a hydraulic excavator over a long period of slewing operation, it can cause rattles during slewing, which can adversely affect the operator's operation. It can also lead to failures in other parts, such as the slewing drive unit. However, it is sometimes difficult to determine whether rattles during slewing are caused by flaking in the slewing bearing. For this reason, disassembly work performed when the rattles are not caused by flaking may result in wasted effort.

[0003] In response to this, Patent Document 1 discloses a technique for measuring the amount of rattle in the axial and radial directions of a slewing bearing using a displacement sensor in order to periodically grasp the state of flaking in the slewing bearing. According to the technique in Patent Document 1, a displacement sensor such as an eddy current type is attached to the outer ring or upper rotating body of the slewing bearing so that it faces the upper end face or outer diameter face of the inner ring. Then, the amount of rattle in the slewing bearing is detected by measuring the distance from the inner ring using this displacement sensor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] European Patent Application Publication No. 1528356 Summary of the Invention [Problem to be solved by the invention]

[0005] The above-mentioned conventional technology recommends eddy current non-contact displacement sensors, which are less susceptible to the effects of grease and sediment. However, if iron particles in the grease or sediment get into the gap between the displacement sensor and the surface being measured, it can cause problems such as a deterioration in measurement accuracy, damage to the sensor, and wear on the outer diameter surface of the inner ring. This can make it impossible to stably measure (monitor) the slewing bearing.

[0006] An object of the present invention is to provide a construction machine that can stably monitor a slewing bearing. [Means for solving the problem]

[0007] The present invention preferably relates to a construction machine comprising a lower running body, an upper rotating body rotatably mounted on the lower running body, a working device mounted at the front of the upper rotating body, a counterweight mounted at the rear of the upper rotating body, and a slewing bearing mounted between the lower running body and the upper rotating body, wherein the slewing bearing comprises an outer ring attached to the upper rotating body side and having an outer ring raceway, an inner ring attached to the lower running body side and having an inner ring raceway, a plurality of rolling elements arranged to be able to roll between the outer ring raceway and the inner ring raceway, and a cage for holding the rolling elements, wherein at least one inclination detection device is attached to each of an outer ring side member which is a member that includes the outer ring and rotates integrally with the outer ring, and an inner ring side member which includes the inner ring and rotates integrally with the inner ring, or at least two inclination detection devices are attached to the outer ring side member, each of which detects inclination at a position. [Effects of the Invention]

[0008] According to the present invention, the slewing bearing can be stably monitored. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a partially cutaway left side view showing a hydraulic excavator according to an embodiment. [Figure 2] 1 is a cross-sectional view showing a slewing bearing, a slewing frame, a center frame, a tilt detection device, etc. according to a first embodiment. [Figure 3] FIG. 3 is an enlarged cross-sectional view showing the left side portion in FIG. 2. [Figure 4] FIG. 4 is a cross-sectional view taken from the same position as FIG. 3, showing an exaggerated tilted state of the slewing bearing. [Figure 5] FIG. 2 is a plan view of the slewing bearing as seen from above. [Figure 6] FIG. 4 is a characteristic diagram showing an example of the change over time in the angular difference between the outer ring and the inner ring during initial operation of the slewing bearing and when replacement is required. [Figure 7] FIG. 2 is a block diagram showing an inclination detection device, a maximum angle difference calculation device, and the like that monitor the slewing bearing. [Figure 8] 8 is a flowchart showing processing performed by the maximum angle difference calculation device in FIG. 7. [Figure 9] FIG. 4 is a cross-sectional view showing a first modified example taken in the same position as in FIG. 3. [Figure 10] 3 is a cross-sectional view taken in a position similar to that of FIG. 2, showing a slewing bearing, a slewing frame, and an inclination detection device according to a second embodiment. [Figure 11] FIG. 11 is a cross-sectional view taken from the same position as FIG. 10, showing an exaggerated state of the slewing bearing tilted. [Figure 12] FIG. 2 is a plan view of the slewing bearing as seen from above. [Figure 13] FIG. 11 is a cross-sectional view showing a second modified example taken in the same position as in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings, taking as an example a case where the present invention is applied to a hydraulic excavator, which is a typical construction machine (work machine), and more specifically, to an extra-large hydraulic excavator. Note that each step in the flowchart shown in Fig. 8 is represented by the letter "S" (for example, step 1 = "S1").

[0011] In the following description, the front side of the hydraulic excavator 1 is defined as the working implement 9 side, and the rear side is defined as the counterweight 19 side, which is opposite the working implement 9. In this case, the front side of the upper rotating body 16 is defined as the working implement 9 side, and the rear side is defined as the counterweight 19 side. In addition, the front side of the lower traveling body 2 is defined as the idler wheel 5 side, and the rear side is defined as the drive wheel 6 side. In addition, the left-right direction of the hydraulic excavator 1 (upper rotating body 16, lower traveling body 2) is defined as a direction perpendicular to the front-to-rear direction.

[0012] Figures 1 to 8 show a first embodiment. In Figure 1, a hydraulic excavator 1 serving as a construction machine (work machine) is equipped with a crawler-type travelling lower body 2, an upper rotating body 16 rotatably mounted on the lower body 2, and a working device 9 provided on the upper rotating body 16. The lower body 2 and the upper rotating body 16 form a vehicle body of the hydraulic excavator 1. The vehicle body is travelling and rotatable.

[0013] For this purpose, a slewing device 21 that rotates the upper slewing body 16 on the lower traveling body 2 is provided between the lower traveling body 2 and the upper slewing body 16. The slewing device 21 includes a slewing bearing 22 that supports the upper slewing body 16 so as to be rotatable relative to the lower traveling body 2 about an axis OO (FIG. 2), and a slewing drive device (not shown) that includes a slewing hydraulic motor (not shown).

[0014] The lower running body 2 comprises a center frame 3 (Figure 2) located in the center and supporting the upper rotating body 16, left and right side frames 4 (only the left side is shown) provided on both the left and right sides of the center frame 3 and extending in the fore-and-aft direction, idler wheels 5 provided on one side in the lengthwise direction of each side frame 4 (the front side in the fore-and-aft direction), drive wheels 6 provided on the other side in the lengthwise direction of each side frame 4 (the rear side in the fore-and-aft direction), tracks 7 wound around the idler wheels 5 and drive wheels 6, and left and right hydraulic motors for running (not shown) that drive each drive wheel 6.

[0015] As shown in Fig. 2, a cylindrical body 8 is provided on the center frame 3. An inner ring 23 of a slewing bearing 22 is attached to the cylindrical body 8. The cylindrical body 8 has a large diameter and is fixed onto the upper plate 3A of the center frame 3 by means of welding or the like, with the axis OO, which is the center of rotation, as its center.

[0016] As shown in Fig. 1 , a working device 9, also called a front device or a working machine, is provided on the front side of an upper rotating body 16 so as to be capable of raising and lowering. The hydraulic excavator 1 performs work such as excavating earth and sand using the working device 9. The working device 9 includes, for example, a boom 10 rotatably attached to a rotating frame 17 of the upper rotating body 16, an arm 11 rotatably attached to the tip of the boom 10, and a bucket 12 as a working tool rotatably attached to the tip of the arm 11. The working device 9 also includes a boom cylinder 13 that drives the boom 10, an arm cylinder 14 that drives the arm 11, and a bucket cylinder 15 that drives the bucket 12.

[0017] The upper rotating body 16 is rotatably mounted on the cylindrical body 8 of the lower traveling body 2 via a slewing bearing 22 of a slewing device 21. The upper rotating body 16 rotates on the lower traveling body 2 by being driven by a slewing drive device (hydraulic motor for slewing) of the slewing device 21. The upper rotating body 16 is equipped with a slewing frame 17 which serves as a base, a cab 18 which is provided on the front left side of the slewing frame 17 and which defines an operator's cab, a counterweight 19 which is provided on the rear end side of the slewing frame 17, and an engine 20 which serves as a prime mover for the hydraulic excavator 1.

[0018] As shown in FIG. 2, an outer ring 25 of the slewing bearing 22 is attached to the underside of the slewing frame 17. Although not shown, a slewing drive device of the slewing device 21 is also attached to the slewing frame 17. The slewing drive device includes a hydraulic motor for slewing as a rotation source, a speed reduction mechanism for reducing the rotation of the hydraulic motor for slewing, and a pinion for outputting the rotation reduced by the speed reduction mechanism. The pinion is engaged with an internal gear 23J provided on the inner ring 23 of the slewing bearing 22. The pinion rotates and revolves around the internal gear 23J of the inner ring 23, thereby rotating the slewing frame 17 (upper slewing body 16) on the cylindrical body 8 (lower running body 2).

[0019] As shown in Fig. 1, the cab 18 is disposed in front of the upper rotating structure 16. Inside the cab 18, there are provided a driver's seat where the operator sits, travel levers and working levers for operating the hydraulic excavator 1, a monitor 44 as a display device that displays information required by the operator, and the like. By operating the travel levers and working levers, the operator can perform travel using the lower traveling structure 2, rotation of the upper rotating structure 16, excavation using the working implement 9, and the like. Excavation using the hydraulic excavator 1 is usually performed in the state shown in Fig. 1, that is, with the front side of the upper rotating structure 2 (working implement 9) positioned in front of the lower traveling structure 2 (idler wheels 5).

[0020] The counterweight 19 is formed as a heavy object for balancing the weight with the working device 9. The engine 20 as a prime mover drives a hydraulic pump (not shown). The prime mover (power source, driving source) for driving the hydraulic pump can be configured as the engine 20 alone, which is an internal combustion engine, or it may be configured as, for example, "an engine and an electric motor" or "an electric motor alone."

[0021] The hydraulic pump draws hydraulic oil stored in a hydraulic oil tank (not shown) and discharges (supplies) the pressurized oil toward a control valve device (not shown). The hydraulic pump supplies the pressurized oil to various hydraulic actuators (hydraulic cylinders, hydraulic motors) such as the boom cylinder 13 via the control valve device.

[0022] The control valve device is a group of control valves consisting of multiple directional control valves. The control valve device distributes pressure oil discharged from the hydraulic pump to multiple hydraulic actuators (hydraulic cylinders, hydraulic motors) such as the boom cylinder 13 in response to the operation of the travel lever and the work lever. This allows the hydraulic excavator 1 to perform operations such as traveling, swinging, and excavation.

[0023] Next, the slewing bearing 22 of the slewing device 21 will be described.

[0024] The slewing bearing 22 is a rolling bearing that supports the upper slewing body 16 so that it can rotate relative to the lower running body 2. The slewing bearing 22 is provided between the center frame 3 (cylindrical body 8) of the lower running body 2 and the slewing frame 17 of the upper slewing body 16. The slewing bearing 22 is configured as a three-row roller bearing that combines two rows of thrust roller bearings (first thrust roller bearing, second thrust roller bearing) and one row of radial roller bearing. The slewing bearing 22 includes an inner ring 23, an outer ring 25, a plurality of first thrust rollers 30, a plurality of second thrust rollers 31, a plurality of radial rollers 32, a first thrust cage 33, a second thrust cage 34, and a radial cage 35.

[0025] The inner ring 23 is formed in an annular shape and is fixed to the upper surface of the cylindrical body 8 using bolts or the like (not shown). The inner ring 23 is formed as a three-stage stepped cylindrical member having an upper cylindrical portion 23A having the smallest outer diameter, a middle cylindrical portion 23B having the largest outer diameter, and a lower cylindrical portion 23C having an outer diameter smaller than that of the middle cylindrical portion 23B and larger than that of the upper cylindrical portion 23A.

[0026] The stepped surface connecting the outer circumferential surface of upper-stage cylindrical portion 23A and the outer circumferential surface of middle-stage cylindrical portion 23B serves as inner ring-side thrust raceway surface 23D on which first thrust roller 30 rolls. The outer circumferential surface of middle-stage cylindrical portion 23B serves as inner ring-side radial raceway surface 23E on which radial roller 32 rolls. The stepped surface connecting the outer circumferential surface of middle-stage cylindrical portion 23B and the outer circumferential surface of lower-stage cylindrical portion 23C serves as inner ring-side thrust raceway surface 23F on which second thrust roller 31 rolls.

[0027] A seal groove 23G for attaching a seal 24 is provided around the entire circumference on the upper surface of the upper cylindrical portion 23A of the inner ring 23. A seal groove 23H for attaching a seal 29 is provided around the entire circumference on a portion of the outer peripheral surface of the lower cylindrical portion 23C of the inner ring 23 that is below the lower end surface of the outer ring 25. An internal gear 23J is formed around the entire circumference on the inner peripheral side (radially inside) of the inner ring 23. The internal gear 23J meshes with a pinion of the slewing drive device.

[0028] The outer ring 25 is formed in an annular shape. The outer ring 25 is provided on the outer peripheral side (radially outward) of the inner ring 23 and concentric with the axis OO of the inner ring 23. The outer ring 25 forms an annular roller accommodating space 26 between itself and the inner ring 23. The outer ring 25 includes an annular upper outer ring segment 27 and an annular lower outer ring segment 28 disposed below the upper outer ring segment 27. The upper outer ring segment 27 and the lower outer ring segment 28 are fixed to the underside of the revolving frame 17 with bolts or the like (not shown) in a butted relationship.

[0029] The upper outer ring segment 27 is formed as a three-stage stepped cylindrical member having an upper-stage cylindrical portion 27A with the smallest inner diameter, a middle-stage cylindrical portion 27B with an inner diameter larger than that of the upper-stage cylindrical portion 27A, and a lower-stage cylindrical portion 27C with an inner diameter larger than that of the upper-stage cylindrical portion 27A and the middle-stage cylindrical portion 27B. The stepped surface connecting the inner circumferential surfaces of the upper-stage cylindrical portion 27A and the middle-stage cylindrical portion 27B forms an outer ring-side thrust raceway surface 27D on which first thrust roller 30 rolls. The inner circumferential surface of the lower-stage cylindrical portion 27C forms an outer ring-side radial raceway surface 27E on which radial roller 32 rolls.

[0030] Lower outer ring segment 28 is formed as a two-stage stepped cylindrical member having upper cylindrical portion 28A with a large inner diameter and lower cylindrical portion 28B with a small inner diameter. The stepped surface connecting the inner peripheral surface of upper cylindrical portion 28A and the inner peripheral surface of lower cylindrical portion 28B forms outer ring-side thrust raceway surface 28C on which second thrust roller 31 rolls.

[0031] The roller accommodating space 26 is an annular space formed between the inner ring 23 and the outer ring 25. A plurality of first thrust rollers 30, a plurality of second thrust rollers 31, and a plurality of radial rollers 32 are accommodated in the roller accommodating space 26 so as to be able to roll.

[0032] The first thrust rollers 30 are disposed between the inner ring side thrust raceway surface 23D and the outer ring side thrust raceway surface 27D. The first thrust rollers 30 support the inner ring 23 and the outer ring 25 so that they can rotate relative to each other about the axis OO, while bearing the thrust load applied between them. The first thrust rollers 30 are disposed in the roller accommodating space 26 so that they can roll about a roller center axis XX ( FIG. 3 ) that is perpendicular to the axis OO of the inner ring 23 and the outer ring 25 and extends radially. The first thrust rollers 30 roll (revolve while rotating) between the inner ring side thrust raceway surface 23D and the outer ring side thrust raceway surface 27D, thereby allowing relative rotation between the inner ring 23 and the outer ring 25.

[0033] The second thrust rollers 31 are disposed between the inner ring-side thrust raceway surface 23F and the outer ring-side thrust raceway surface 28C. Like the first thrust rollers 30, the second thrust rollers 31 support the inner ring 23 and the outer ring 25 so that they can rotate relative to each other about the axis OO, while bearing the thrust load applied between them. Like the first thrust rollers 30, the second thrust rollers 31 are disposed in the roller accommodating space 26 so as to be rollable about a roller center axis XX ( FIG. 3 ) that is perpendicular to the axis OO of the inner ring 23 and the outer ring 25 and extends radially. The second thrust rollers 31 roll (revolve while rotating) between the inner ring-side thrust raceway surface 23F and the outer ring-side thrust raceway surface 28C, thereby allowing relative rotation between the inner ring 23 and the outer ring 25.

[0034] Radial rollers 32 are provided between inner ring side radial raceway surface 23E and outer ring side radial raceway surface 27E. Radial rollers 32 support inner ring 23 and outer ring 25 so that they can rotate relative to each other about axis OO, while bearing the radial load applied between them. Radial rollers 32 are arranged in roller accommodating space 26 so that they can roll about roller center axis YY ( FIG. 3 ), which is parallel to axis OO of inner ring 23 and outer ring 25. Radial rollers 32 roll (revolve while rotating) between inner ring side radial raceway surface 23E and outer ring side radial raceway surface 27E, allowing relative rotation between inner ring 23 and outer ring 25.

[0035] The first thrust cage 33 rollably holds the first thrust rollers 30 between the inner ring side thrust raceway surface 23D and the outer ring side thrust raceway surface 27D. The second thrust cage 34 rollably holds the second thrust rollers 31 between the inner ring side thrust raceway surface 23F and the outer ring side thrust raceway surface 28C. The radial cage 35 rollably holds the radial rollers 32 between the inner ring side radial raceway surface 23E and the outer ring side radial raceway surface 27E.

[0036] Seals 24, 29 are provided between inner ring 23 and outer ring 25. Seals 24, 29 are formed in an annular shape from an elastic material such as rubber or flexible resin. Seal 24 is attached to seal groove 23G provided in the upper end surface of inner ring 23. Seal 29 is attached to seal groove 23H provided in the outer peripheral surface of the lower end side of inner ring 23. Seals 24, 29 prevent foreign matter from entering roller accommodating space 26 from the outside and also prevent lubricant (grease) in roller accommodating space 26 from leaking to the outside.

[0037] As described above, the slewing bearing 22 includes an outer ring 25 (upper outer ring segment 27, lower outer ring segment 28) fixed to the slewing frame 17 of the upper slewing body 16, and an inner ring 23 fixed to the center frame 3 (cylindrical body 8) of the lower running body 2 and having an internal gear 23J formed on its inner peripheral surface. An outer ring side thrust raceway 27D, an outer ring side radial raceway 27E, and an outer ring side thrust raceway 28C are provided on the inner peripheral surface of the outer ring 25 (upper outer ring segment 27, lower outer ring segment 28). An inner ring side thrust raceway 23D, an inner ring side radial raceway 23E, and an inner ring side thrust raceway 23F are provided on the outer peripheral surface of the inner ring 23.

[0038] The plurality of first thrust rollers 30 are provided rollably between the outer ring side thrust raceway surface 27D and the inner ring side thrust raceway surface 23D. The plurality of radial rollers 32 are provided rollably between the outer ring side radial raceway surface 27E and the inner ring side radial raceway surface 23E. The plurality of second thrust rollers 31 are provided rollably between the outer ring side thrust raceway surface 28C and the inner ring side thrust raceway surface 23F. The first thrust cage 33 rollably holds the first thrust rollers 30. The radial cage 35 rollably holds the radial rollers 32. The second thrust cage 34 rollably holds the second thrust rollers 31.

[0039] Grease (lubricating oil) for smooth rolling of rollers 30, 31, and 32, which are rolling elements, is poured into roller accommodating space 26. Roller accommodating space 26 is sealed by seals 24 and 29 provided in the gap between the inner circumferential surface of outer ring 25 (upper outer ring segment 27, lower outer ring segment 28) and the outer circumferential surface of inner ring 23. Seals 24 and 29 are made of an elastic material such as rubber.

[0040] 3 and 4 show cross sections of the slewing frame 17 and slewing bearing 22 on the working implement 9 side (front side of the vehicle body). In this case, FIG. 3 shows a state when not performing excavation operations. In contrast, FIG. 4 exaggerates the state in which the slewing bearing 22 is deformed due to the load applied to the bucket 12 of the working implement 9 during excavation operations. As shown in an exaggerated manner in FIG. 4, the slewing bearing 22 receives a moment load at the front of the vehicle body (forward of the upper rotating body 16), which causes the outer ring 25 to tend to tilt forward relative to the inner ring 23. As this tilt (front-rear tilt) occurs, wear and flaking progress on the outer ring-side thrust raceway surface 27D and the inner ring-side thrust raceway surface 23D with which the first thrust roller 30 contacts, and the angular difference θ between the inner ring 23 and the outer ring 25 (angular difference θ in the front-rear direction) increases.

[0041] In this embodiment, a change in the inclination (the angular difference θ between the inner ring 23 and the outer ring 25) accompanying the progression of wear and peeling of the slewing bearing 22 is monitored. That is, in this embodiment, the longitudinal inclination of the slewing bearing 22 during excavation operation (the angular difference θ in the longitudinal direction between the inner ring 23 and the outer ring 25), more specifically, the maximum value of the longitudinal inclination of the slewing bearing 22 (the maximum value of the angular difference θ) is monitored.

[0042] For this reason, in this embodiment, an outer wheel side inclination sensor 41 serving as an inclination detection device is attached to the inner peripheral surface of the upper part of the outer wheel 25. The outer wheel side inclination sensor 41 detects (measures) the angle (inclination angle) of the upper rotating body 16 (more specifically, the outer wheel 25) with respect to the horizontal. That is, the outer wheel side inclination sensor 41 detects the inclination angle of the upper rotating body 16 (outer wheel 25) in the front-to-rear direction on the front side (working device 9 side) of the upper rotating body 16 (outer wheel 25). In other words, the outer wheel side inclination sensor 41 detects the angle in the pitch direction (pitch angle) of the upper rotating body 16 (outer wheel 25).

[0043] In addition, in this embodiment, an inner wheel-side inclination sensor 42 is attached as an inclination detection device to the upper end surface of the inner wheel 23. The inner wheel-side inclination sensor 42 detects (measures) the angle (inclination angle) of the lower running body 2 (more specifically, the inner wheel 23) with respect to the horizontal. That is, the inner wheel-side inclination sensor 42 detects the inclination angle in the front-to-rear direction of the lower running body 2 (inner wheel 23) on the front side (idler wheel 5 side) in the front-to-rear direction of the lower running body 2 (inner wheel 23). In other words, the inner wheel-side inclination sensor 42 detects the angle in the pitch direction (pitch angle) of the lower running body 2 (inner wheel 23).

[0044] The outer-race-side tilt sensor 41 and the inner-race-side tilt sensor 42 may be, for example, a MEMS (Micro Electro Mechanical Systems) tilt sensor (capacitive tilt sensor) that detects tilt based on changes in electrical output caused by tilt. The MEMS tilt sensor includes, for example, a fixed electrode and a movable electrode. The movable electrode moves relative to the fixed electrode in response to the tilt of the MEMS tilt sensor. This changes the capacitance between the fixed electrode and the movable electrode. The MEMS tilt sensor can detect the tilt angle based on the change in capacitance between the fixed electrode and the movable electrode.

[0045] The outer wheel side inclination sensor 41 and the inner wheel side inclination sensor 42 are not limited to MEMS inclination sensors, and various inclination sensors such as electrolyte inclination sensors, pendulum inclination sensors, quartz inclination sensors, and acceleration sensors can be used. The outer wheel side inclination sensor 41 is installed so as to be able to detect the longitudinal inclination angle (pitch angle) of the upper rotating body 16 (outer wheel 25). The inner wheel side inclination sensor 42 is installed so as to be able to detect the longitudinal inclination angle (pitch angle) of the lower running body 2 (inner wheel 23). The number of detection axes of the inclination sensor may be one, two, or three. The number of detection axes of the inclination sensor can be determined so as to be able to detect the inclination angle in the required direction and obtain this inclination angle with the required accuracy.

[0046] Figure 5 is a plan view of the slewing bearing 22. The area 51 surrounded by a solid line in Figure 5 corresponds to the working device 9 side (the front side of the vehicle body), i.e., the position where wear and flaking are most likely to occur in the circumferential direction of the outer ring side thrust raceway surface 27D and the inner ring side thrust raceway surface 23D. This area 51 corresponds to the most preferable position for installing the outer ring side inclination sensor 41 and the inner ring side inclination sensor 42 in order to determine the wear and flaking state of the slewing bearing 22 and, ultimately, the need for replacement of the slewing bearing 22.

[0047] 5 correspond to positions where it is recommended to attach the outer ring side inclination sensor 41 and the inner ring side inclination sensor 42 in order to grasp the circumferential wear state of the outer ring side thrust raceway surface 27D and the inner ring side thrust raceway surface 23D in more detail. For example, by comparing the detection values ​​of the outer ring side inclination sensor 41 and the inner ring side inclination sensor 42 attached to area 51 with the detection values ​​of the outer ring side inclination sensor (not shown) and the inner ring side inclination sensor (not shown) attached to areas 52, 53, and 54, it is possible to grasp the overall circumferential wear state of the outer ring side thrust raceway surface 27D and the inner ring side thrust raceway surface 23D.

[0048] Fig. 6 shows an example of the change over time in the difference between the angle measured by the outer ring-side inclination sensor 41 and the angle measured by the inner ring-side inclination sensor 42, i.e., the difference (angle difference) between the inclination angle of the outer ring 25 and the inclination angle of the inner ring 23. A characteristic line 71 in Fig. 6 shows an example of the change over time in the angle difference (initial operating status) during initial operation (when the slewing bearing 22 is brand new). A characteristic line 72 in Fig. 6 shows an example of the change over time in the angle difference (operating status at the time of replacement determination) immediately before it is determined that the slewing bearing 22 needs replacement (immediately before reaching the threshold value).

[0049] When a moment load is applied to the front of the vehicle body (front of the upper rotating body 16) during excavation, the difference (inclination angle difference) between the inclination angle of the outer ring 25 and the inclination angle of the inner ring 23 becomes the largest based on the rigidity of the outer ring 25 and the inner ring 23, etc. Then, as the first thrust rollers 30 intermittently pass over the outer ring-side thrust raceway surface 27D and the inner ring-side thrust raceway surface 23D, fatigue-induced peeling occurs on the outer ring-side thrust raceway surface 27D and the inner ring-side thrust raceway surface 23D, and the maximum value of the angle difference (maximum angle difference) increases. Therefore, in this embodiment, a threshold value for the angle difference (slewing bearing replacement determination threshold value) converted from the allowable amount of wear is set, and when the angle difference reaches (or exceeds) the threshold value, a notification is issued to that effect, urging the user to replace the slewing bearing 22. Normally, the hydraulic excavator 1 excavates in the state shown in Figure 1, i.e., with the front side of the upper rotating body 2 (working device 9) positioned in front of the lower running body 2 (idler wheel 5), and the upper rotating body 2 is rotated from this position to release soil.

[0050] 7 is a block diagram showing tilt detection devices (inner ring-side tilt sensor 42, outer ring-side tilt sensor 41) that monitor the slewing bearing 22, a maximum angle difference calculation device 43, etc. Note that the "tilt detection device" in FIG. 7 corresponds to the "tilt sensor." In this case, FIG. 7 corresponds to a case where three or more tilt detection devices (tilt sensors) are provided, for example, a case where tilt detection devices (tilt sensors) are provided not only in the area 51 surrounded by a solid line in FIG. 5 but also in the areas 52, 53, and 54 surrounded by dashed lines in FIG. 5.

[0051] As shown in Fig. 7, the hydraulic excavator 1 is equipped with a plurality of tilt detection devices, in other words, an inner wheel-side tilt sensor 42 and an outer wheel-side tilt sensor 41 corresponding to at least two tilt detection devices, a maximum angle difference calculation device 43 serving as a controller (control device), and a monitor 44 serving as an informing device (display device) that notifies (displays) information about the slewing bearing 22. Note that in Figs. 1 and 7, in addition to the monitor 44 (hereinafter referred to as the internal monitor 44) inside the cab 18 of the hydraulic excavator 1, a monitor 45 (hereinafter referred to as the external monitor 45) is also installed outside the hydraulic excavator 1 as an informing device (display device).

[0052] The inner race side inclination sensor 42 and the outer race side inclination sensor 41 are provided on the slewing bearing 22. The inner race side inclination sensor 42 and the outer race side inclination sensor 41 detect the inclination angle at their respective positions (mounting positions). The inner race side inclination sensor 42 and the outer race side inclination sensor 41 are connected to a maximum angle difference calculation device 43. The inner race side inclination sensor 42 and the outer race side inclination sensor 41 output signals (detection signals) corresponding to the detected inclination angles to the maximum angle difference calculation device 43.

[0053] The maximum angular difference calculation device 43 receives signals (detection signals) corresponding to the tilt angles detected by the inner race-side tilt sensor 42 and the outer race-side tilt sensor 41. The maximum angular difference calculation device 43 calculates the angular difference from the tilt angles detected by the inner race-side tilt sensor 42 and the outer race-side tilt sensor 41. The maximum angular difference calculation device 43 corresponds to, for example, a microcomputer equipped with a central processing unit (CPU), memory, etc. The maximum angular difference calculation device 43 not only calculates the angular difference between the inner race 23 and the outer race 25 of the slewing bearing 22, but also determines the condition of the slewing bearing 22 from the calculated angular difference. That is, the maximum angular difference calculation device 43 determines whether the calculated angular difference is equal to or greater than a preset threshold. The threshold can be set as the minimum value of an unacceptable angular difference, i.e., an angular difference at which the slewing bearing 22 needs to be replaced. As a result, the maximum angular difference calculation device 43 can determine that the slewing bearing 22 needs to be replaced when the calculated angular difference is equal to or greater than the threshold.

[0054] The maximum angle difference calculation device 43 is connected to an internal monitor 44 via, for example, a wired cable 46. The maximum angle difference calculation device 43 is also connected to an external monitor 45 via wireless communication 47, for example, wireless LAN communication, mobile communication, satellite communication, or the like. The maximum angle difference calculation device 43 outputs a command (display command signal) to the internal monitor 44 to display various information including information about the slewing bearing 22 (for example, the state of the slewing bearing 22, the necessity of the slewing bearing 22). The maximum angle difference calculation device 43 also outputs a command (display command signal) to the external monitor 45 to display various information including information about the slewing bearing 22 (for example, the state of the slewing bearing 22, the necessity of the slewing bearing 22).

[0055] The internal monitor 44 receives commands (display command signals) from the maximum angle difference calculation device 43. The internal monitor 44 corresponds to a monitor device installed in the cab 18 of the hydraulic excavator 1. The internal monitor 44 displays various information for the operator of the hydraulic excavator 1. The internal monitor 44 displays information based on the commands (display command signals) from the maximum angle difference calculation device 43. For example, the internal monitor 44 displays, based on the command from the maximum angle difference calculation device 43, that the slewing bearing 22 needs to be replaced.

[0056] The external monitor 45 receives an input of a command (display command signal) from the maximum angle difference calculation device 43. The external monitor 45 corresponds to a monitor device of a management device (information processing device, server computer) installed at a location remote from the hydraulic excavator 1. The external monitor 45 can display various information for the administrator who manages the hydraulic excavator 1, the maintenance person in charge of maintaining the hydraulic excavator 1, the person in charge of the manufacturer of the hydraulic excavator 1 who supplies maintenance parts, etc. The external monitor 45 displays information based on the command (display command signal) from the maximum angle difference calculation device 43. For example, the external monitor 45 displays, based on the command from the maximum angle difference calculation device 43, that the slewing bearing 22 needs to be replaced.

[0057] Fig. 8 is a flowchart showing processing (monitoring processing of the slewing bearing 22) performed by the maximum angle difference calculation device 43. The processing in Fig. 8 is performed periodically, manually or automatically, so as to properly grasp the degree of progress of wear and flaking of the slewing bearing 22, in other words, so as to properly determine the time to replace the slewing bearing 22. Furthermore, the processing in Fig. 8 is performed while the hydraulic excavator 1 is in operation (during excavation work).

[0058] The processing of Fig. 8 by the maximum angle difference calculation device 43 is started by a start operation by the operator or by an automatic start command issued by a timer function of the maximum angle difference calculation device 43. When the processing of Fig. 8 is started, the maximum angle difference calculation device 43 performs detection (measurement) using the inclination detection devices (inner wheel-side inclination sensor 42, outer wheel-side inclination sensor 41) in S1. This detection is performed while the hydraulic excavator 1 is in operation (during excavation work), particularly so as to include excavation when the angle difference between the outer wheel 25 and the inner wheel 23 is at its maximum, as shown in Fig. 6.

[0059] In S2 following S1, it is determined whether the maximum angle difference between the inclination angle on the inner ring 23 side and the inclination angle on the outer ring 25 side is equal to or greater than a threshold value. That is, it is determined whether the maximum value of the difference (maximum angle difference) between the inclination angle detected by the inner ring-side inclination sensor 42 and the inclination angle detected by the outer ring-side inclination sensor 41 is equal to or greater than a threshold value. The threshold value is set as an angle difference (determination value) at which the slewing bearing 22 needs to be replaced due to the progression of wear and peeling.

[0060] If S2 returns "NO," that is, if it is determined that the maximum angle difference between the inclination angle on the inner ring 23 side and the inclination angle on the outer ring 25 side is less than the threshold value, the process proceeds to S3. In this case, the slewing bearing 22 corresponds to a normal state in which replacement is not required. Therefore, in S3, "slewing bearing normal" is displayed on the display device (internal monitor 44, external monitor 45). If "slewing bearing normal" is displayed on the display device (internal monitor 44, external monitor 45) in S3, the process proceeds to END. If necessary, the process may return to START and repeat the processes from S1 onwards.

[0061] On the other hand, if S2 returns "YES," that is, if it is determined that the maximum angle difference between the inclination angle on the inner ring 23 side and the inclination angle on the outer ring 25 side is equal to or greater than the threshold value, the process proceeds to S4. In this case, it corresponds to a state in which the slewing bearing 22 needs to be replaced. For this reason, in S4, "Replace slewing bearing" is displayed on the display device (internal monitor 44, external monitor 45). This notifies the operator, manager, etc. that the slewing bearing 22 needs to be replaced, and it is possible to urge them to replace the slewing bearing 22. If "Replace slewing bearing" is displayed on the display device (internal monitor 44, external monitor 45) in S4, the process proceeds to END. If necessary, the process may return to START and repeat the processes from S1 onwards.

[0062] As described above, in this embodiment, the hydraulic excavator 1 serving as a construction machine includes the lower traveling body 2, the upper rotating body 16, the working implement 9, the counterweight 19, and the slewing bearing 22. The lower traveling body 2 is capable of traveling. The upper rotating body 16 is rotatably provided on the lower traveling body 2. The working implement 9 is provided at the front portion of the upper rotating body 16. More specifically, the working implement 9 is attached to the front side of the slewing frame 17. The counterweight 19 is provided at the rear portion of the upper rotating body 16. More specifically, the counterweight 19 is attached to the rear side of the slewing frame 17 (the opposite side to the working implement 9). The slewing bearing 22 is provided between the lower traveling body 2 and the upper rotating body 16. More specifically, the slewing bearing 22 is provided between the slewing frame 17 and the cylindrical body 8 of the center frame 3.

[0063] The slewing bearing 22 includes an outer ring 25, an inner ring 23, a plurality of rolling elements (a plurality of first thrust rollers 30, a plurality of second thrust rollers 31, a plurality of radial rollers 32), and a cage (a first thrust cage 33, a second thrust cage 34, a radial cage 35). The outer ring 25 is attached to the upper slewing body 16 side. More specifically, the outer ring 25 is attached to the slewing frame 17. The outer ring 25 has outer ring raceways (an outer ring side thrust raceway surface 27D, an outer ring side thrust raceway surface 28C, and an outer ring side radial raceway surface 27E).

[0064] The inner ring 23 is attached to the lower running body 2. More specifically, the inner ring 23 is attached to the cylindrical body 8 of the center frame 3. The inner ring 23 has an inner ring raceway (inner ring side thrust raceway surface 23D, inner ring side thrust raceway surface 23F, inner ring side radial raceway surface 23E). The rolling elements (first thrust roller 30, second thrust roller 31, radial roller 32) are disposed so as to be rollable between the outer ring raceway (outer ring side thrust raceway surface 27D, outer ring side thrust raceway surface 28C, outer ring side radial raceway surface 27E) and the inner ring raceway (inner ring side thrust raceway surface 23D, inner ring side thrust raceway surface 23F, inner ring side radial raceway surface 23E). The cages (first thrust cage 33, second thrust cage 34, radial cage 35) hold the rolling elements (first thrust rollers 30, second thrust rollers 31, radial rollers 32).

[0065] In this embodiment, the slewing bearing 22 is configured as a three-row roller bearing including a first thrust roller bearing including a first thrust roller 30, a second thrust roller bearing including a second thrust roller 31, and a radial roller bearing including a radial roller 32. The first thrust roller bearing and the second thrust roller bearing are arranged spaced apart from each other above and below. The radial roller bearing is arranged between the first thrust roller bearing and the second thrust roller bearing.

[0066] Here, a member that includes the outer ring 25 and rotates integrally with the outer ring 25 is referred to as an outer ring side member. For example, the outer ring side member corresponds to the outer ring 25 and the upper rotating body 16. Also, a member that includes the inner ring 23 and rotates integrally with the inner ring 23 is referred to as an inner ring side member. For example, the inner ring side member corresponds to the inner ring 23 and the lower running body 2. Furthermore, at least one inclination sensor 41, 42 is attached to each of the outer ring side member and the inner ring side member as an inclination detection device that detects inclination at each position. That is, the outer ring 25, which is the outer ring side member, is attached with the outer ring side inclination sensor 41, and the inner ring 23, which is the inner ring side member, is attached with the inner ring side inclination sensor 42.

[0067] The outer wheel side inclination sensor 41 and the inner wheel side inclination sensor 42 detect the inclination angle with respect to the same reference (horizontal) at their respective positions. That is, the outer wheel side inclination sensor 41 and the inner wheel side inclination sensor 42 detect the inclination angle with respect to horizontal at their respective mounting positions. In this case, the outer wheel side inclination sensor 41 and the inner wheel side inclination sensor 42 detect the inclination angle in the fore-and-aft direction of the hydraulic excavator 1, which is the vehicle body. For example, the outer wheel side inclination sensor 41 detects the fore-and-aft inclination angle (pitch angle) of the upper rotating body 16 (outer wheels 25). The inner wheel side inclination sensor 42 detects the fore-and-aft inclination angle (pitch angle) of the lower traveling body 2 (inner wheels 23).

[0068] The hydraulic excavator 1 also includes a maximum angle difference calculation device 43 as a determination unit. The maximum angle difference calculation device 43 determines the condition of the slewing bearing 22 (for example, the degree of wear and flaking, and whether replacement is necessary) based on the difference in the inclination angles detected by the outer-wheel-side inclination sensor 41 and the inner-wheel-side inclination sensor 42. The outer-wheel-side inclination sensor 41, which is one of the inclination sensors 41, 42, is attached to the outer wheel 25, which serves as the outer-wheel-side member. In this case, the outer wheel-side inclination sensor 41 is attached to the working implement 9 side (front side) of the outer wheel 25 in the circumferential direction. Meanwhile, the inner wheel-side inclination sensor 42, which is the other of the inclination sensors 41, 42, is attached to the inner wheel 23, which serves as the inner-wheel-side member. In this case, the inner wheel-side inclination sensor 42 is attached to the working implement 9 side (front side, the idler wheel 5 side of the undercarriage 2) of the inner wheel 23 in the circumferential direction.

[0069] The hydraulic excavator 1 according to the embodiment has the above-described configuration, and its operation will now be described.

[0070] For example, an operator sits in the driver's seat inside the cab 18 and starts the engine 20. When the engine 20 starts, the engine 20 drives the hydraulic pump. Pressurized oil discharged from the hydraulic pump is discharged toward the traveling hydraulic motor, the swing hydraulic motor, the boom cylinder 13, the arm cylinder 14, the bucket cylinder 15, etc., in response to the operation of a traveling lever and an operation lever provided around the driver's seat. This enables the hydraulic excavator 1 to travel using the lower traveling structure 2, swing the upper swing structure 16, excavate using the work device 9, etc.

[0071] Here, the slewing device 21 that rotates the upper slewing body 16 on the lower travelling body 2 is composed of a slewing bearing 22 provided between the upper slewing body 16 and the lower travelling body 2, and a slewing drive device (not shown) fixed to the slewing frame 17 of the upper slewing body 16. When rotating the upper slewing body 16 on the lower travelling body 2, the slewing hydraulic motor of the slewing drive device is rotationally driven to rotate the pinion of the slewing drive device. The pinion of the slewing drive device is engaged with an internal gear 23J of an inner ring 23 that constitutes the slewing bearing 22. The pinion revolves while rotating around the internal gear 23J of the inner ring 23 based on the rotation of the slewing hydraulic motor, and the revolution force of the pinion is transmitted to the slewing frame 17. As a result, the slewing frame 17 rotates on the cylindrical body 8 via the slewing bearing 22, and the upper slewing body 16 can be rotated on the lower travelling body 2.

[0072] When the hydraulic excavator 1 is operating, the outer wheel side inclination sensor 41 attached to the outer wheel 25 detects the inclination angle at its attached position (i.e., the inclination angle of the outer wheel 25 with respect to the horizontal) and outputs the detected inclination angle to the maximum angle difference calculation device 43. The inner wheel side inclination sensor 42 attached to the inner wheel 23 detects the inclination angle at its attached position (i.e., the inclination angle of the inner wheel 23 with respect to the horizontal) and outputs the detected inclination angle to the maximum angle difference calculation device 43.

[0073] The maximum angle difference calculation device 43 calculates the angle difference, which is the difference between the inclination angle of the outer ring 25 and the inclination angle of the inner ring 23, and determines the state of the slewing bearing 22 (for example, the degree of wear and flaking, and whether replacement is necessary) from the calculated angle difference. The internal monitor 44 and the external monitor 45 display the state of the slewing bearing 22 (for example, the degree of wear and flaking, and whether replacement is necessary) based on a command from the maximum angle difference calculation device 43.

[0074] 2 and 3, the outer race-side inclination sensor 41 is attached to the inner peripheral surface of the upper part of the outer race 25. The inner race-side inclination sensor 42 is attached to the upper end surface of the inner race 23. Therefore, the outer race-side inclination sensor 41 and the inner race-side inclination sensor 42 can detect the inclination angles of the outer race 25 and the inner race 23 without being affected by grease or earth and sand.

[0075] 6 to 8, the maximum angle difference calculation device 43 calculates the angle difference (maximum angle difference) between the outer ring 25 and the inner ring 23 during operation. The angle difference (maximum angle difference) correlates with the progress of wear and flaking on the outer ring-side thrust raceway surface 27D and the inner ring-side thrust raceway surface 23D. Therefore, the maximum angle difference calculation device 43 can determine the progress of wear and flaking on the outer ring-side thrust raceway surface 27D and the inner ring-side thrust raceway surface 23D from the angle difference (maximum angle difference). This allows the maximum angle difference calculation device 43 to determine with high accuracy whether or not the slewing bearing 22 needs to be replaced.

[0076] Furthermore, if tilt detection devices (inner ring-side tilt sensor 42 and outer ring-side tilt sensor 41) are installed in region 51 indicated by solid lines and regions 52, 53, and 54 indicated by dotted lines in Figure 5, the condition of the slewing bearing 22 can be determined, for example, as follows. Assuming that wear is virtually nonexistent near the rear of the vehicle body, the upper rotating body 16 is rotated approximately 90 degrees or approximately 180 degrees relative to the undercarriage 2 to calculate the angular difference, and this angular difference is compared with the value in the initial state. This makes it possible to determine the amount of wear and the circumferential wear range of the outer ring-side thrust raceway surface 27D and the inner ring-side thrust raceway surface 23D. In this case, for example, the usable life of the slewing bearing 22 (the time until replacement) can be extended by operating the vehicle body so as not to apply a large load to the circumferential position of the inner ring 23 where wear is expected to progress.

[0077] As described above, according to the first embodiment, at least one inclination sensor 41 is attached to each of the outer ring 25, which serves as the outer ring-side member, and the inner ring 23, which serves as the inner ring-side member. That is, at least one outer ring-side inclination sensor 41 is attached to the outer ring 25, and at least one inner ring-side inclination sensor 42 is attached to the inner ring 23. The outer ring-side inclination sensor 41 and the inner ring-side inclination sensor 42 detect inclination at their respective positions. Therefore, inclination (the inclination of the outer ring 25 and the inner ring 23) can be detected without being affected by iron particles or sediment in the grease in the slewing bearing 22. This allows the state of the slewing bearing 22 (e.g., wear, flaking, and whether replacement is required) to be determined based on the inclination (the inclination of the outer ring 25 and the inclination of the inner ring 23) that is not affected by iron particles or sediment in the grease. As a result, the slewing bearing 22 can be monitored stably.

[0078] According to the embodiment, the outer race-side inclination sensor 41 and the inner race-side inclination sensor 42 detect the inclination angle relative to the same reference (horizontal) at their respective positions. Therefore, by comparing the inclination angles detected by the outer race-side inclination sensor 41 and the inner race-side inclination sensor 42, the state of the slewing bearing 22 can be determined.

[0079] According to the embodiment, a maximum angle difference calculation device 43 is provided as a determination unit that determines the state of the slewing bearing 22 based on the difference in tilt angle detected by the outer ring side tilt sensor 41 and the inner ring side tilt sensor 42. Therefore, the maximum angle difference calculation device 43 can determine the state (level) of wear and the state (level) of peeling of the slewing bearing 22, and ultimately whether or not the slewing bearing 22 needs to be replaced, based on the difference in tilt angle.

[0080] According to the embodiment, an outer ring-side inclination sensor 41 is attached to the front side (work device 9 side) of the outer ring 25, which is the outer ring-side member, and an inner ring-side inclination sensor 42 is attached to the front side (work device 9 side, idler wheel 5 side) of the inner ring 23, which is the inner ring-side member. Therefore, the state of the slewing bearing 22 (for example, the state of wear and flaking, whether replacement is necessary) can be determined based on the inclination of the front sides of the outer ring 25 and inner ring 23, which are prone to wear and flaking.

[0081] According to the embodiment, the slewing bearing 22 is configured as a three-row roller bearing including a first thrust roller bearing, a second thrust roller bearing, and a radial roller bearing. Therefore, the slewing bearing 22 configured as a three-row roller bearing can be monitored.

[0082] In the first embodiment, the outer ring side inclination sensor 41 is attached to the inner peripheral surface of the upper part of the outer ring 25, which is the outer ring side member, and the inner ring side inclination sensor 42 is attached to the upper end surface of the inner ring 23, which is the inner ring side member. However, this is not limiting, and as in a first modified example shown in FIG. 9 , the outer ring side inclination sensor 41 may be attached, for example, to the outer peripheral surface of the upper part of the outer ring 25 and on the front side (working device 9 side). The outer ring side inclination sensor 41 may be attached, for example, to the lower end surface of the lower part of the outer ring 25 and on the front side (working device 9 side). The outer ring side inclination sensor 41 may be attached, for example, to the upper surface of the swivel frame 17, which is the outer ring side member, and on the front side (working device 9 side).

[0083] The outer race side inclination sensor 41 may be attached, for example, to the underside of the swivel frame 17, which serves as the outer race side member, and on the front side (working device 9 side). On the other hand, the inner race side inclination sensor 42 may be attached to the outer peripheral surface of the cylindrical body 8, which serves as the inner race side member, and on the front side (working device 9 side). Although not shown, the inner race side inclination sensor 42 may be attached to the inner peripheral surface of the cylindrical body, which serves as the inner race side member, and on the front side (working device 9 side). Furthermore, the outer race side inclination sensor 41 and the inner race side inclination sensor 42 may be attached to a position other than the front side (working device 9 side) of the vehicle body, i.e., to the rear side, left side, or right side, which is a position away from the front side (working device 9 side) of the vehicle body in the circumferential direction of the slewing bearing 22.

[0084] 10 to 12 show a second embodiment. In the second embodiment, the tilt detection device (tilt sensor) is attached to the outer ring side member, not to the inner ring side member. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and their description will be omitted.

[0085] FIG. 12 is a plan view of the slewing bearing 22. In the second embodiment, outer race side inclination sensors 81, 82 are attached to areas 51 and 53 enclosed by solid lines in FIG. 12. That is, in the second embodiment, the first outer race side inclination sensor 81 is attached to area 51 on the working implement 9 side (front side of the vehicle body) of the slewing bearing 22. In addition, the second outer race side inclination sensor 82 is attached to area 53 on the counterweight 19 side (rear side of the vehicle body) of the slewing bearing 22. FIG. 10 is a cross-sectional view of the slewing bearing 22 taken along line AA in FIG. 12. The first outer race side inclination sensor 81 and the second outer race side inclination sensor 82 are attached to the inner peripheral surface of the upper part of the outer race 25.

[0086] Here, a member that includes the outer ring 25 and rotates integrally with the outer ring 25 is referred to as an outer ring side member. For example, the outer ring side member corresponds to the outer ring 25 and the upper rotating body 16. Also, a member that includes the inner ring 23 and rotates integrally with the inner ring 23 is referred to as an inner ring side member. For example, the inner ring side member corresponds to the inner ring 23 and the lower running body 2. In the second embodiment, at least two outer ring side inclination sensors 81, 82 are attached to the outer ring side member as inclination detection devices that detect inclination at their respective positions. That is, the outer ring 25, which is the outer ring side member, is attached with the outer ring side inclination sensors 81, 82.

[0087] In this case, the first outer race side inclination sensor 81, which is one of the outer race side inclination sensors 81, 82, is attached to the working implement 9 side (front side) in the circumferential direction of the outer race 25, which is the outer race side member. The second outer race side inclination sensor 82, which is the other of the outer race side inclination sensors 81, 82, is attached to the counterweight 19 side (rear side) in the circumferential direction of the outer race 25, which is the outer race side member. The first outer race side inclination sensor 81 and the second outer race side inclination sensor 82 are connected to the maximum angle difference calculation device 43 (FIGS. 1 and 7).

[0088] FIG. 11 shows in an exaggerated manner the deformation of the slewing bearing 22 and the slewing frame 17 due to the load applied to the bucket 12 (FIG. 1) of the work implement 9 (FIG. 1) during excavation. During excavation, the maximum angle difference calculation device 43 calculates an angle difference, which is the difference between the tilt angle detected (measured) by the first outer wheel side tilt sensor 81 on the front side of the vehicle body and the tilt angle detected (measured) by the second outer wheel side tilt sensor 82 on the rear side of the vehicle body. When the calculated angle difference (maximum angle difference) exceeds a preset threshold, the maximum angle difference calculation device 43 determines that the slewing bearing 22 needs to be replaced. The maximum angle difference calculation device 43 outputs a command to the internal monitor 44 (FIGS. 1 and 7) and the external monitor 45 (FIGS. 1 and 7) to display that the slewing bearing 22 needs to be replaced.

[0089] In the second embodiment, the first outer ring side inclination sensor 81 and the second outer ring side inclination sensor 82 as described above are attached to the outer ring 25, and the basic operation is not particularly different from that of the first embodiment. That is, in the second embodiment, at least two inclination sensors 81, 82 are attached to the outer ring 25, which is the outer ring side member. Therefore, similar to the first embodiment, the slewing bearing 22 can be stably monitored.

[0090] In particular, according to the second embodiment, one of the outer-race-side inclination sensors 81, 82 is attached to the front side (work implement 9 side) of the outer-race 25, which is the outer-race-side member, and the other of the outer-race-side inclination sensors 81, 82 is attached to the rear side (counterweight 19 side) of the outer-race 25. Therefore, the state of the slewing bearing 22 (e.g., the state of wear and flaking, whether replacement is necessary) can be determined based on the inclination between the front side (work implement 9 side), where wear and flaking are likely to progress, and the rear side (counterweight 19 side), where wear and flaking are less likely to progress. Moreover, by attaching all of the inclination sensors 81, 82 to the outer-race-side member, wiring from the undercarriage 2 side is not required. Therefore, wiring between the inclination sensors 81, 82 and the maximum angle difference calculation device 43 can be simplified and easily performed.

[0091] In the second embodiment, the outer ring side inclination sensors 81, 82 are attached to the front side (work implement 9 side) and rear side (counterweight 19 side) of the inner peripheral surface of the outer ring 25, which is the outer ring side member. However, this is not limiting, and for example, as in a second modified example shown in Fig. 13, the outer ring side inclination sensors 81, 82 may be attached to the front side (work implement 9 side) and rear side (counterweight 19 side) of the upper surface of the swivel frame 17, which is the outer ring side member.

[0092] In the first embodiment described above, an example was given in which the slewing bearing 22 was configured as a three-row roller bearing made up of a combination of two-row thrust roller bearings and one-row radial roller bearing. However, the slewing bearing is not limited to this, and may be configured as, for example, a single-row thrust roller bearing, or a two-row roller bearing made up of a combination of a single-row thrust roller bearing and a single-row radial roller bearing.

[0093] Furthermore, although the orbiting bearing 22 is configured as a "roller bearing" in which the rolling elements are "rollers," it may also be configured as a "ball bearing" in which the rolling elements are "balls." That is, the orbiting bearing can be configured with at least one row of rolling bearings. This also applies to the second embodiment, the first modified example, and the second modified example.

[0094] In the first embodiment, the second embodiment, the first modified example, and the second modified example (hereinafter referred to as "each embodiment"), the outer ring side member to which the outer ring side inclination sensors 41, 81, 82 are attached is described as the outer ring 25 or the revolving frame 17. However, the outer ring side member is not limited to this, and may be a member on the upper revolving body side other than the revolving frame.

[0095] In each embodiment, the case where the inner race-side member to which the inner race-side inclination sensor 42 is attached is the inner race 23 or the cylindrical body 8 has been described as an example. However, the inner race-side member is not limited to this, and may be a member on the lower running body side other than the cylindrical body.

[0096] In each embodiment, the construction machine has been described by taking a hydraulic excavator 1 as an example. However, the construction machine is not limited to this, and the present invention can be widely applied to various construction machines equipped with a slewing device, such as a hydraulic crane.

[0097] It goes without saying that each embodiment is an example, and partial substitution or combination of the configurations shown in different embodiments and modifications is possible. [Explanation of symbols]

[0098] 1. Hydraulic excavator (construction machinery) 2 Lower running body (inner ring side member) 8 Cylinder (inner ring side member) 9 Work equipment 16 Upper rotating body (outer ring side member) 17 Swing frame (outer ring side member) 19 Counterweight 22 Slewing bearing 23 Inner ring (inner ring side member) 23D, 23F Inner ring thrust raceway (inner ring raceway) 23E Inner ring radial raceway surface (inner ring raceway) 25 Outer ring (outer ring side member) 27D, 28C Outer ring thrust raceway (outer ring raceway) 27E Outer ring radial raceway (outer ring raceway) 30 First thrust roller (rolling element) 31 Second thrust roller (rolling element) 32 Radial roller (rolling element) 33 First thrust retainer (retainer) 34 Second thrust retainer (retainer) 35 Radial cage (retainer) 41 Outer ring tilt sensor (tilt detection device) 42 Inner ring tilt sensor (tilt detection device) 43 Maximum angle difference calculation device (judgment unit) 81 First outer ring side tilt sensor (tilt detection device) 82 Second outer ring side tilt sensor (tilt detection device)

Claims

1. A lower running body; An upper rotating body rotatably provided on the lower traveling body; A working device provided at a front portion of the upper rotating body; A counterweight provided at the rear of the upper rotating body; A slewing bearing is provided between the lower traveling body and the upper rotating body, The slewing bearing is An outer ring attached to the upper rotating body and having an outer ring raceway; An inner ring attached to the lower running body and having an inner ring raceway; A plurality of rolling elements rollably disposed between the outer ring raceway and the inner ring raceway; A construction machine equipped with a cage that holds the rolling elements, A construction machine characterized in that at least one tilt detection device is attached to each of an outer ring side member which includes the outer ring and rotates integrally with the outer ring, and an inner ring side member which includes the inner ring and rotates integrally with the inner ring, or at least two tilt detection devices are attached to the outer ring side member to detect tilt at each of the positions.

2. 2. The construction machine according to claim 1, wherein each of said tilt detection devices detects a tilt angle relative to the same reference at each position.

3. 3. The construction machine according to claim 2, further comprising a determination unit that determines a state of the slewing bearing based on a difference between the tilt angles detected by each of the tilt detection devices.

4. one of the tilt detection devices is attached to the working device side of the outer race side member, 2. The construction machine according to claim 1, wherein another of the tilt detection devices is attached to the inner wheel side member on the side of the work implement.

5. one of the tilt detection devices is attached to the working device side of the outer race side member, 2. The construction machine according to claim 1, wherein another of the tilt detection devices is attached to the counterweight side of the outer wheel side member.

6. The slewing bearing is a first thrust roller bearing and a second thrust roller bearing arranged vertically spaced apart from each other; 2. The construction machine according to claim 1, further comprising: a radial roller bearing disposed between the first thrust roller bearing and the second thrust roller bearing.

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