Work machine

Abstract

Provided is a work machine capable of appropriately measuring a wear amount of a slew bearing.　The work machine comprises: a lower traveling body; an upper turning body supported so as to be rotatable with respect to the lower traveling body; and a slew bearing provided between the upper turning body and the lower traveling body. The slew bearing comprises an inner ring fixed to the lower traveling body, an outer ring fixed to the upper turning body, and a plurality of rolling bodies arranged between the inner ring and the outer ring and rolling as the outer ring rotates with respect to the inner ring. The work machine comprises: a part to be detected that protrudes radially outward from the outer peripheral surface of the inner ring and is continuous in the circumferential direction; a distance measurement sensor that is fixed to the outer ring at a position facing the part to be detected in the extension direction of the rotation center axis of the upper turning body and measures the distance to the part to be detected; and scraping members that are fixed to the outer ring, each at a position different from the distance measurement sensor in the circumferential direction of the slew bearing, the scraping members scraping foreign matter on the measurement surface of the part to be detected facing the distance measurement sensor. The scraping members are disposed on both sides of the distance measurement sensor in the circumferential direction of the slew bearing.

Description

Work machinery

[0001] The present invention relates to a work machine including a lower traveling body and an upper rotating body.

[0002] A known construction machine includes a lower traveling body and an upper rotating body that is rotatably supported on the lower traveling body via a slewing bearing. The slewing bearing used in such a construction machine can experience wear and flaking on the raceway surface as the upper rotating body repeatedly rotates, causing rattle.

[0003] Therefore, for example, Patent Document 1 discloses a technology for detecting the amount of wear of a slewing bearing by using an eddy current distance measuring sensor provided on the outer ring of the slewing bearing to measure the distance to a measurement bracket provided on the inner ring of the slewing bearing.

[0004] EP 1 528 356

[0005] However, if soil or sand (an example of foreign matter) from the work site mixes with the grease leaking from the slewing bearing and accumulates on the measurement bracket, a new problem arises in that the distance sensor is no longer able to measure the distance properly.

[0006] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a work machine that can appropriately measure the amount of wear of a slewing bearing.

[0007] In order to achieve the above object, the present invention provides a work machine comprising: a lower running body; an upper rotating body rotatably supported on the lower running body; and a slewing bearing provided between the upper rotating body and the lower running body, wherein the slewing bearing comprises an inner ring fixed to the lower running body, an outer ring fixed to the upper rotating body, and a plurality of rolling elements disposed between the inner ring and the outer ring and rolling with rotation of the outer ring relative to the inner ring; The rotating bearing is characterized in that it comprises a circumferentially continuous detectable portion, a distance measuring sensor fixed to the outer ring at a position facing the detectable portion in the extension direction of the rotation center axis of the upper rotating body, and measuring the distance to the detectable portion, and a scraping member fixed to the outer ring at a position different from the distance measuring sensor in the circumferential direction of the rotating bearing, and scraping off foreign matter from the measurement surface of the detectable portion facing the distance measuring sensor, the scraping member being arranged on both sides of the distance measuring sensor in the circumferential direction of the rotating bearing.

[0008] According to the present invention, it is possible to obtain a work machine that is capable of appropriately measuring the amount of wear of a slewing bearing. Problems, configurations, and effects other than those described above will become apparent from the following description of the embodiments.

[0009] Fig. 5 is a side view of a hydraulic excavator. Fig. 6 is a cross-sectional view of a slewing bearing. Fig. 7 is a cross-sectional view showing the state of the slewing bearing when the front working machine is operated. Fig. 8 is a cross-sectional view of a slewing bearing equipped with a play measuring device. Fig. 9 is an enlarged view of region V in Fig. 4. Fig. 5 is a view from the arrow VI in Fig. 6. Fig. 7 is a control block diagram of a hydraulic excavator. Fig. 8 is a flowchart of an operation control process.

[0010] [Configuration of Hydraulic Excavator 1] An embodiment of a hydraulic excavator 1 (work machine) according to the present invention will be described with reference to the drawings. However, a specific example of the work machine is not limited to the hydraulic excavator 1, and may be any machine (for example, a crane) that has a lower traveling body 2 and an upper rotating body 3. Furthermore, unless otherwise specified, the terms front, back, left, and right in this specification are based on the viewpoint of an operator who is on board and operating the hydraulic excavator 1.

[0011] Fig. 1 is a side view of a hydraulic excavator 1. As shown in Fig. 1 , the hydraulic excavator 1 includes a lower traveling body 2, an upper rotating body 3 supported by the lower traveling body 2, and a slewing bearing 20 interposed between the lower traveling body 2 and the upper rotating body 3.

[0012] The lower traveling body 2 is provided with a pair of left and right crawlers 4, which are endless tracks. The pair of left and right crawlers 4 are rotated independently by driving a traveling motor 5. As a result, the hydraulic excavator 1 travels. However, the lower traveling body 2 may be of a wheeled type instead of the crawlers 4.

[0013] The upper rotating body 3 is rotatably supported by the lower traveling body 2 via a swing bearing 20. The upper rotating body 3 swings relative to the lower traveling body 2 as the swing motor 6 rotates. Ideally, the swing center axis X of the upper rotating body 3 extends in a direction perpendicular to the mounting surface of the hydraulic excavator 1. The upper rotating body 3 mainly includes a swing frame 7 serving as a base, a cab (operator's seat) 8 disposed on the front left side of the swing frame 7, a counterweight 9 disposed at the rear of the swing frame 7, and a front work machine 10 (working device) attached to the front center of the swing frame 7 so as to be rotatable in the vertical direction.

[0014] The cab 8 is disposed adjacent to the front working implement 10 in the left-right direction (the width direction of the vehicle body). More specifically, the cab 8 is disposed to the left (one side in the left-right direction) of the front working implement 10. However, the location of the cab 8 is not limited to the example described above, and the cab 8 may be disposed on one side of the front working implement 10 in the left-right direction.

[0015] The cab 8 is formed with a space for an operator to ride in and operate the hydraulic excavator 1. Inside the cab 8, there is a seat on which the operator sits, and an operation device 8a (see FIG. 7) that is operated by the operator seated in the seat. The operation device 8a accepts operations by the operator to operate the hydraulic excavator 1, and outputs an operation signal indicating the content of the accepted operation to the controller 50 (see FIG. 7). When the operator operates the operation device 8a, the lower traveling body 2 travels, the upper rotating body 3 swings, and the front working implement 10 operates. Specific examples of the operation device 8a include a lever, a steering wheel, and a pedal.

[0016] The front work implement 10 includes a boom 11 supported on the upper rotating body 3 so that it can be raised and lowered, an arm 12 supported at the tip of the boom 11 so that it can rotate (crowd, dump), a bucket 13 supported at the tip of the arm 12 so that it can rotate (crowd, dump), a boom cylinder 14 that drives the boom 11, an arm cylinder 15 that drives the arm 12, and a bucket cylinder 16 that drives the bucket 13. Note that specific examples of the attachment are not limited to the bucket 13, and may include a grapple, cutter, crusher, breaker, etc. The counterweight 9 is a heavy object that has an arc shape when viewed from above and is used to balance the weight of the front work implement 10.

[0017] [Configuration of Slewing Bearing 20] Fig. 2 is a cross-sectional view of the slewing bearing 20. The slewing bearing 20 is provided between the lower running body 2 and the upper rotating body 3, and realizes smooth rotation of the upper rotating body 3 relative to the lower running body 2. As shown in Fig. 2, for example, the slewing bearing 20 mainly includes an inner ring 21, an outer ring 22, rolling elements 23a, 23b, and 23c, a cage 24, and seals 25a and 25b.

[0018] The extension direction of the swivel center axis X corresponds to the axial direction of the swivel bearing 20 (hereinafter, sometimes simply referred to as the "axial direction"), the direction perpendicular to the extension direction of the swivel center axis X corresponds to the radial direction of the swivel bearing 20 (hereinafter, sometimes simply referred to as the "radial direction"), and the rotation direction of the upper swivel body 3 (outer ring 22) corresponds to the circumferential direction of the swivel bearing 20 (hereinafter, sometimes simply referred to as the "circumferential direction").

[0019] The inner ring 21 and the outer ring 22 have a generally ring-shaped outer shape. The inner ring 21 is fixed to the lower running body 2 (more specifically, inside a circle formed on the upper surface of the lower running body 2). The outer ring 22 is fixed to the lower surface of the upper rotating body 3 and rotates together with the rotating upper rotating body 3. A convex portion 21d is formed on the outer peripheral surface of the inner ring 21, and a plurality of rolling surfaces 21a, 21b, and 21c are formed on the convex portion 21d in the circumferential direction. A concave portion 22d is formed on the inner peripheral surface of the outer ring 22, and a plurality of rolling surfaces 22a, 22b, and 22c are formed on the concave portion 22d in the circumferential direction.

[0020] The rolling surfaces 21a, 22a face each other at a predetermined distance in the axial direction of the orbiting bearing 20, and the outer peripheral surface of the inner ring 21 and the inner peripheral surface of the outer ring 22 form an accommodation chamber 26a that accommodates a rolling element 23a (described later). The rolling surfaces 21b, 22b face each other at a predetermined distance in the axial direction of the orbiting bearing 20, and the outer peripheral surface of the inner ring 21 and the inner peripheral surface of the outer ring 22 form an accommodation chamber 26b that accommodates a rolling element 23b (described later). The rolling surfaces 21c, 22c face each other at a predetermined distance in the radial direction of the orbiting bearing 20, and form an accommodation chamber 26c that accommodates a rolling element 23c (described later) together with the inner wall of a groove formed in the bottom of the recess 22d of the outer ring 22.

[0021] The rolling elements 23a, 23b, and 23c are so-called "rollers" that have a generally cylindrical outer shape. The multiple rolling elements 23a are arranged in a housing chamber 26a formed by the rolling surfaces 21a and 22a. The multiple rolling elements 23b are arranged in a housing chamber 26b formed by the rolling surfaces 21b and 22b. The multiple rolling elements 23c are arranged in a housing chamber 26c formed by the rolling surfaces 21c and 22c. The rolling elements 23a, 23b, and 23c roll (rotate and revolve) as the outer ring 22 rotates relative to the inner ring 21.

[0022] The cage 24 maintains the spacing between the arranged rolling elements 23 a, 23 b, and 23 c. The interior of the orbiting bearing 20 is filled with grease (lubricant) that lubricates the spaces between the rolling elements 23 a, 23 b, and 23 c and the rolling surfaces 21 a, 21 b, 21 c, 22 a, 22 b, and 22 c.

[0023] The seals 25a, 25b have a generally ring-shaped outer shape. The seals 25a, 25b are fixed to both sides of the inner ring 21 in the axial direction of the orbiting bearing 20. The tips of the seals 25a, 25b are in contact with the outer ring 22 over the entire circumference. The seals 25a, 25b prevent grease from leaking out from inside the orbiting bearing 20 and also prevent dust from entering the inside of the orbiting bearing 20 from the outside.

[0024] The configuration of the slewing bearing 20 is not limited to the above-described example, and any well-known configuration used in a work machine can be adopted.

[0025] FIG. 3 is a cross-sectional view showing the state of the slewing bearing 20 when the front working implement 10 is operating. When the front working implement 10 is not operating (e.g., excavating), the rolling surfaces 21a, 22a, 21b, 22b, and 21c, 22c are parallel to each other, as shown in FIG. 2. On the other hand, when the front working implement 10 is performing excavation, a moment load is generated on the front side of the hydraulic excavator 1, causing the outer ring 22 to tilt (more specifically, tilt downward toward the front) with respect to the mounting surface of the hydraulic excavator 1, as shown in FIG. 3. As a result, the rolling surfaces 21a, 22a, 21b, 22b, and 21c, 22c become non-parallel. When the upper rotating body 3 rotates in this state, wear and flaking of the rolling surfaces 21a to 21c and 22a to 22c progress, causing increased rattle of the slewing bearing 20.

[0026] [Configuration of the gap measurement device 30] Figure 4 is a cross-sectional view of the slewing bearing 20 equipped with the gap measurement device 30. Figure 5 is an enlarged view of area V in Figure 4. Figure 6 is a view of Figure 5 as viewed from the direction of arrow VI. The hydraulic excavator 1 is equipped with the gap measurement device 30. The gap measurement device 30 is a device that measures the amount of wear of the slewing bearing 20 (more specifically, the inclination angle θ of the outer ring 22 shown in Figure 3). As shown in Figures 4 to 6, the gap measurement device 30 mainly includes a measurement bracket 31, a sensor bracket 32, a distance measurement sensor 33, a pair of scrapers 34a, 34b (scraping members), and a connecting wall 35.

[0027] The measurement bracket 31 is fixed to the inner ring 21 (more specifically, to the outer peripheral surface of the inner ring 21). The measurement bracket 31 is composed of, for example, a cylindrical portion 36 and a flange portion 37 (detection target portion). The cylindrical portion 36 is a cylindrical portion that is fitted onto the inner ring 21 and fixed to the inner ring 21 with bolts. The flange portion 37 is a flange portion that protrudes radially outward from the outer peripheral surface of the cylindrical portion 36 (i.e., the inner ring 21) and continues circumferentially. The upper surface of the flange portion 37 (the surface facing the upper rotating body 3 and the distance measurement sensor 33) is a measurement surface 38 that is the target of measurement by the distance measurement sensor 33.

[0028] The sensor bracket 32 ​​is a member that fixes the distance measurement sensor 33 to the outer ring 22. The sensor bracket 32 ​​supports the distance measurement sensor 33. The sensor bracket 32 ​​is also fixed to the scrapers 34a and 34b. This indirectly fixes the distance measurement sensor 33 to the outer ring 22. However, the sensor bracket 32 ​​may be omitted and the distance measurement sensor 33 may be fixed directly to the outer ring 22.

[0029] The distance measurement sensor 33 is fixed to the lower surface of the outer ring 22 (the surface facing the undercarriage 2) via a sensor bracket 32. The distance measurement sensor 33 faces the flange portion 37 at a predetermined distance in the axial direction of the slewing bearing 20. The distance measurement sensor 33 measures the distance to the flange portion 37 and outputs a distance signal indicating the measured distance to the controller 50. An eddy current sensor, for example, can be used as the distance measurement sensor 33, but the specific example of the distance measurement sensor 33 is not limited to this.

[0030] The pair of scrapers 34a, 34b are fixed to the underside of the outer ring 22, outside the outer peripheral surface of the inner ring 21 in the radial direction of the orbiting bearing 20. The scrapers 34a, 34b are arranged at positions different from the distance measuring sensor 33 in the circumferential direction of the orbiting bearing 20. More specifically, the scrapers 34a, 34b are arranged on both sides of the distance measuring sensor 33 in the circumferential direction of the orbiting bearing 20. The scrapers 34a, 34b are scraping members that scrape off foreign matter accumulated on the measurement surface 38 of the flange portion 37. However, one of the scrapers 34a, 34b may be omitted. Since the scrapers 34a, 34b have a common configuration, the scraper 34a will be described in detail below.

[0031] The scraper 34a is a plate-shaped member that is perpendicular to the circumferential direction of the orbiting bearing 20. A groove 39a is formed in the scraper 34a. The groove 39a is recessed radially outward from the end face of the scraper 34a on the inner side (the side facing the inner ring 21) in the radial direction of the orbiting bearing 20. The groove 39a also penetrates the plate-shaped scraper 34a in the thickness direction (the circumferential direction of the orbiting bearing 20).

[0032] The groove 39a is formed so that the flange portion 37 fits therein and avoids interference with the flange portion 37. Among the wall surfaces that define the groove 39a, a scraping surface 40a that defines the upper end of the groove 39a faces the measurement surface 38 at a predetermined distance in the axial direction of the slewing bearing 20. The scraping surface 40a scrapes off foreign matter (e.g., soil and gravel mixed with grease) that has accumulated on the measurement surface 38 as the upper slewing body 3 rotates (the outer ring 22 rotates).

[0033] The connecting wall 35 is disposed radially outward of the swing bearing 20 from the distance measuring sensor 33. The connecting wall 35 also connects the pair of scrapers 34a, 34b. That is, the distance measuring sensor 33 is covered on both circumferential sides by the scrapers 34a, 34b, and on the radially outer side by the connecting wall 35. This makes it possible to prevent soil or gravel that has entered between the lower traveling body 2 and the upper swing body 3 from coming into contact with the distance measuring sensor 33.

[0034] In this embodiment, the sensor bracket 32, the distance measurement sensor 33, the scrapers 34a and 34b, and the connecting wall 35 are provided at two locations spaced apart in the circumferential direction. However, the number of locations where these components (32 to 35) are provided is not limited to two, and they may be provided at one location or three or more locations. Furthermore, when the components (32 to 35) are provided at two or more locations, they are preferably provided at equal intervals (180° intervals in this embodiment) around the circumferential direction of the slewing bearing 20. Furthermore, when the components (32 to 35) are provided at two locations, they are preferably provided at positions that are aligned in the fore-and-aft direction (positions on an imaginary line that passes through the center of the slewing bearing 20 and extends in the fore-and-aft direction) when the slewing angle of the upper slewing body 3 is 0°.

[0035] [Configuration of Controller 50] Figure 7 is a control block diagram of the hydraulic excavator 1. As shown in Figure 7, the hydraulic excavator 1 is equipped with a controller 50 having a CPU 51 (Central Processing Unit) and a memory 52. ​​The memory 52 is configured, for example, by a ROM (Read Only Memory), a RAM (Random Access Memory), an HDD (Hard Disk Drive), or a combination of these. The controller 50 realizes the processing described below by having the CPU 51 read and execute program code stored in the memory 52.

[0036] However, the specific configuration of the controller 50 is not limited to this, and may be realized by hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array).

[0037] The controller 50 controls the overall operation of the hydraulic excavator 1. The controller 50 controls the operation of the hydraulic excavator 1 (more specifically, the traveling motor 5, the swing motor 6, the boom cylinder 14, the arm cylinder 15, and the bucket cylinder 16) via a drive circuit (not shown) based on, for example, an operation signal output from the operating device 8a and a distance signal output from the distance measurement sensor 33.

[0038] [Operation Control Process] Fig. 8 is a flowchart of the operation control process. The operation control process is a process for controlling (permitting or prohibiting) the operation of the hydraulic excavator 1 in accordance with the amount of wear of the slewing bearing 20 measured by the play measurement device 30. The controller 50 repeatedly executes the operation control process shown in Fig. 8 at predetermined time intervals, for example, while the hydraulic excavator 1 is operating.

[0039] First, the controller 50 measures the distance to the measurement surface 38 of the flange portion 37 (hereinafter referred to as the "measured distance") using the distance measurement sensor 33 (S11). More specifically, the controller 50 may specify the measured distance based on the distance signal output from the distance measurement sensor 33.

[0040] Next, the controller 50 determines whether the distance measured in step S11 is within a predetermined allowable range (S12). The allowable range is the ideal distance from the distance measuring sensor 33 to the measurement surface 38 (e.g., a design distance without wear) plus the allowable amount of wear that is allowable for the hydraulic excavator 1 to operate properly (e.g., allowable range = ideal distance ± allowable amount of wear).

[0041] If the controller 50 determines that the measured distance is within the allowable range (S12: Yes), it permits the operation of the hydraulic excavator 1 (S13). That is, the controller 50 operates the hydraulic actuators (i.e., the travel motor 5, the swing motor 6, the boom cylinder 14, the arm cylinder 15, and the bucket cylinder 16) based on the operation signal output from the operation device 8a. On the other hand, if the controller 50 determines that the measured distance is outside the allowable range (S12: No), it prohibits the operation of the hydraulic excavator 1 (S14). That is, the controller 50 does not operate the hydraulic actuators even if an operation signal is output from the operation device 8a.

[0042] Furthermore, the controller 50 may issue a notification via an alarm device (not shown) of maintenance (typically, replacement) of the slewing bearing 20. The notification device may be, for example, a display disposed in the cab 8 or a management terminal capable of communicating with the hydraulic excavator 1 via a communication network.

[0043] If the components (32 to 35) are provided at two locations, the controller 50 may measure the distances using each of the two distance measuring sensors 33 in step S11. The controller 50 may also determine whether the difference between the two measured distances is less than a predetermined threshold in step S12. Furthermore, the controller 50 may permit the operation of the hydraulic excavator 1 when the difference between the two measured distances is less than the threshold (S12: Yes → S13), and may prohibit the operation of the hydraulic excavator 1 when the difference between the two measured distances is equal to or greater than the threshold (S12: No → S14).

[0044] [Effects of the embodiment] According to the above embodiment, when the upper rotating body 3 rotates, foreign matter accumulated on the measurement surface 38 of the flange portion 37 can be scraped off by the scrapers 34a, 34b, so that the distance measuring sensor 33 can properly measure the distance to the measurement surface 38 (i.e., the amount of wear of the rotating bearing 20) without being affected by foreign matter.

[0045] Furthermore, according to the above embodiment, the scrapers 34a, 34b are arranged on both sides of the distance measuring sensor 33, so that foreign matter can be scraped off at the position measured by the distance measuring sensor 33 regardless of the rotation direction of the upper rotating body 3. This allows the distance to the measurement surface 38 to be measured more appropriately.

[0046] Furthermore, according to the above embodiment, the pair of scrapers 34 a, 34 b and the connecting wall 35 cover three sides of the distance measuring sensor 33, thereby preventing foreign matter from coming into contact with the distance measuring sensor 33. This allows the distance to the measurement surface 38 to be measured more appropriately.

[0047] The above-described embodiments are merely illustrative examples of the present invention, and are not intended to limit the scope of the present invention to these embodiments. Those skilled in the art can implement the present invention in various other forms without departing from the spirit of the present invention.

[0048] DESCRIPTION OF SYMBOLS 1: Hydraulic excavator 2: Lower traveling body 3: Upper rotating body 4: Crawler 5: Travel motor 6: Swing motor 7: Swing frame 8: Cab 8a: Operating device 9: Counterweight 10: Front working machine 11: Boom 12: Arm 13: Bucket 14: Boom cylinder 15: Arm cylinder 16: Bucket cylinder 20: Swing bearing 21: Inner ring 21a to 21c, 22a to 22c: Rolling surface 21d: Convex portion 22: Outer ring 22d: Concave portion 23a to 23c: Rolling element 24: Cage 25a, 25b: Seal 26a, 26b, 26c: Accommodation chamber 30: Playback measuring device 31: Measurement bracket 32: Sensor bracket 33 : Distance measuring sensor 34a, 34b : Scraper 35 : Connection wall 36 : Cylindrical portion 37 : Flange portion 38 : Measurement surface 39a : Groove 40a : Scraping surface 50 : Controller 51 : CPU 52 : Memory

Claims

1. A work machine comprising: a lower running body; an upper rotating body supported rotatably relative to the lower running body; and a slewing bearing provided between the upper rotating body and the lower running body, wherein the slewing bearing comprises: an inner ring fixed to the lower running body; an outer ring fixed to the upper rotating body; and a plurality of rolling elements arranged between the inner ring and the outer ring and rolling as the outer ring rotates relative to the inner ring; the work machine comprising: a detectable part that protrudes radially outward from the outer peripheral surface of the inner ring and is continuous in the circumferential direction; a distance measuring sensor fixed to the outer ring at a position facing the detectable part in the extension direction of the central axis of rotation of the upper rotating body, and that measures the distance to the detectable part; and a scraping member fixed to the outer ring at a position different from the distance measuring sensor in the circumferential direction of the slewing bearing, and that scrapes off foreign matter from the measurement surface of the detectable part that faces the distance measuring sensor, wherein the scraping member is A work machine characterized in that the distance measuring sensor is disposed on both sides of the slewing bearing in the circumferential direction.

2. A work machine as described in claim 1, wherein the scraping member has a groove formed to avoid interference with the detected part, and a scraping surface is provided on the wall surface defining the groove, facing the measurement surface and configured to scrape off foreign matter.

3. A work machine as set forth in claim 1, further comprising a connecting wall that is positioned radially outward of the slewing bearing relative to the distance measuring sensor and that connects the pair of scraping members.

4. A work machine according to claim 1, further comprising a sensor bracket that supports the distance measuring sensor and is fixed to the pair of scraping members.

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