Steering device of construction machinery

Abstract

To achieve high sealability of an O ring sealing a shaft insertion hole of a roller body with lubricating oil.SOLUTION: A supporting shaft 18 constituting a lower guide roller device 15 of a hydraulic shovel 1 includes a large-diameter shaft part 18A positioned in the middle part in the axial direction and a small-diameter shaft part 18B positioned on both sides in the axial direction and having smaller shaft diameter than the large-diameter shaft part 18A. Engagement holes 17 of a pair of holders 16 are respectively constituted of a large-diameter engagement hole part 17A engaging with the large-diameter shaft part 18A and a small-diameter engagement hole part 17B having a smaller hole diameter smaller than the large-diameter engagement hole part 17A and engaging with the small-diameter shaft part 18B. An outer periphery of the large-diameter shaft part 18A includes a large-diameter annular groove 24 over the whole periphery. The outer periphery of the small-diameter shaft part 18B includes a small-diameter annular groove 25 smaller than the large-diameter annular groove 24 over the whole periphery. The large-diameter annular groove 24 is fitted with a large-diameter ring 26 and the small-diameter annular groove 25 is fitted with a small-diameter O ring 27.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a slewing device mounted on a construction machine such as a hydraulic excavator, for example.

Background Art

[0002] A hydraulic excavator, which is representative of construction machines, is equipped with a crawler (track) type lower traveling body in order to travel stably on uneven ground or the like. The crawler type lower traveling body includes a track frame having left and right side frames, a traveling device (sprocket) provided on one end side of the side frame, an idler device provided on the other end side of the side frame, a plurality of upper rollers and lower rollers provided on the side frame and positioned between the traveling device and the idler device, and a crawler wound around the traveling device and the idler device. The crawler is driven by the traveling device and circulates along a certain track by being guided by the idler device, the upper rollers, and the lower rollers.

[0003] The lower roller provided on the lower traveling body is rotatably supported via a support shaft by a pair of holders provided on the lower side of the side frame. The lower roller is provided with a shaft insertion hole through which the support shaft is inserted, and the shaft insertion hole is filled with lubricating oil such as grease for lubricating the sliding portion between the lower roller and the support shaft. O-rings are respectively mounted on both axial ends of the support shaft that fits into the pair of holders. Therefore, the O-ring seals the fitting portion between the holder and the support shaft in a state where both axial ends of the support shaft are fitted into the holder, and seals the lubricating oil in the shaft insertion hole of the lower roller.

[0004] Here, a lower roller is proposed in which two (a total of four) O-rings are attached to one end side and the other end side in the axial direction of the support shaft, respectively. In this prior art, on the axial end side of the support shaft exposed to the outside air in cold regions or the like, an axial end side O-ring with excellent cold resistance performance is arranged, and on the inside of the support shaft exposed to frictional heat due to sliding with the lower roller, an inner O-ring with excellent heat resistance performance is arranged. The axial end side O-ring mainly prevents foreign matter from the outside, such as earth and sand, from entering the fitting portion between the holder and the support shaft. The inner O-ring mainly prevents the lubricating oil filled in the shaft insertion hole of the lower roller from leaking to the outside. Thus, by attaching two types of O-rings with different temperature characteristics to the support shaft, the life of each O-ring can be extended (see Patent Document 1).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Here, the axial end side O-ring and the inner O-ring according to the prior art are arranged adjacent to the outer peripheral surface of the support shaft having the same outer diameter dimension. That is, on the outer peripheral surface of the support shaft, an axial end side annular groove located on the axial end side and an inner annular groove located on the inner side (central side) of the support shaft are formed. An axial end side O-ring with excellent cold resistance performance is attached to the axial end side annular groove, and an inner O-ring with excellent heat resistance performance is attached to the inner annular groove.

[0007] However, the inner O-ring needs to be attached to the inner annular groove after getting over the axial end side annular groove. For this reason, when getting over the axial end side annular groove, there is a problem that the inner O-ring comes into contact with the peripheral edge portion (edge portion) of the axial end side annular groove, and the inner O-ring is damaged.

[0008] In addition, since the shaft-end-side O-ring and the inner O-ring have the same shape, it is difficult to distinguish them visually. For this reason, there is a risk of mistakenly installing the inner O-ring with excellent heat resistance in the shaft-end-side annular groove, or installing the shaft-end-side O-ring with excellent cold resistance in the inner annular groove. As a result, the temperature characteristics of the inner O-ring and the shaft-end-side O-ring do not function effectively, leading to a problem of reduced lifespan for each of them.

[0009] An object of the present invention is to provide a slewing ring device for a construction machine that can improve the sealing performance of an O-ring for sealing lubricating oil in the shaft insertion hole of a slewing ring body.

Means for Solving the Problem

[0010] The present invention relates to a slewing ring device for a construction machine, comprising a pair of holders attached opposite to the vehicle body of the construction machine, shaft fitting holes respectively provided in the pair of holders, a support shaft with both axial ends fitted into the shaft fitting holes of the pair of holders, a slewing ring body having a shaft insertion hole through which the support shaft is inserted and rotatably supported by the support shaft, and O-rings respectively provided between the support shaft and the pair of holders for sealing lubricating oil in the shaft insertion hole of the slewing ring body. In the slewing ring device, the support shaft has a large-diameter shaft portion located at the intermediate part in the axial direction and small-diameter shaft portions located on both sides in the axial direction and having a smaller shaft diameter than the large-diameter shaft portion. The shaft fitting holes of the pair of holders are composed of a large-diameter fitting hole into which the large-diameter shaft portion is fitted and a small-diameter fitting hole having a smaller hole diameter than the large-diameter fitting hole and into which the small-diameter shaft portion is fitted. A large-diameter annular groove is provided over the entire circumference on the outer periphery of the large-diameter shaft portion, and a small-diameter annular groove smaller than the large-diameter annular groove is provided over the entire circumference on the outer periphery of the small-diameter shaft portion. The O-ring is composed of a large-diameter O-ring attached to the large-diameter annular groove and a small-diameter O-ring attached to the small-diameter annular groove.

Effect of the Invention

[0011] According to the present invention, when a large-diameter O-ring rides over a small-diameter annular groove in order to be mounted in a large-diameter annular groove, it is possible to suppress contact of the large-diameter O-ring with the peripheral edge of the small-diameter annular groove. Thereby, the large-diameter O-ring can be mounted in the large-diameter annular groove without being damaged, and its sealing performance can be improved.

Brief Description of the Drawings

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of a slewing ring device for a construction machine according to the present invention will be described in detail with reference to the accompanying drawings, taking the case where it is applied to a hydraulic excavator as an example. In the embodiments, the traveling direction of the hydraulic excavator will be described as the front-rear direction, and the direction orthogonal to the traveling direction will be described as the left-right direction.

[0014] Figs. 1 to 5 show a first embodiment of the present invention. In Fig. 1, a hydraulic excavator 1 includes a self-propelled crawler-type lower traveling body 2, an upper swing body 3 rotatably mounted on the lower traveling body 2, and a working device 4 provided on the front side of the upper swing body 3. The lower traveling body 2 and the upper swing body 3 constitute the vehicle body of the hydraulic excavator 1. The hydraulic excavator 1 performs earth and sand excavation work or the like using the working device 4.

[0015] The upper swing body 3 includes a swing frame 5 serving as a base, a cab 6 mounted on the left front side of the swing frame 5, a counterweight 7 provided at the rear end of the swing frame 5, and an exterior cover 8 provided on the front side of the counterweight 7. The cab 6 defines a driver's cab for the operator to board, and a driver's seat, a travel lever - pedal, and an operation lever (none of which are shown) are provided inside the cab 6. The counterweight 7 maintains the weight balance with the working device 4 provided on the front side of the swing frame 5. The exterior cover 8 covers the mounted equipment (none of which are shown) such as the prime mover, hydraulic pump, and control valve mounted on the swing frame 5.

[0016] The lower traveling body 2 includes a track frame 9 serving as a base. The track frame 9 has a center frame 10 located at the central portion in the left - right direction and a pair of left and right side frames 11 (only the left side is shown) arranged on the left and right with the center frame 10 interposed therebetween, and the side frames 11 extend in the front - rear direction. As shown in Fig. 3, the side frame 11 is surrounded by a left side plate 11A and a right side plate 11B facing each other in the left - right direction at a certain interval and an upper plate (not shown) connecting the upper ends of the left side plate 11A and the right side plate 11B, and is formed as a frame body having a U - shaped cross - sectional shape with an open lower end side. A lower left plate 11C extending in the front - rear direction is welded to the lower end of the left side plate 11A, and a lower right plate 11D extending in the front - rear direction is welded to the lower end of the right side plate 11B.

[0017] On one end side in the longitudinal direction (front-rear direction) of the side frame 11, a traveling device 12 is provided, and on the other end side in the longitudinal direction of the side frame 11, an idler device 31 described later is provided. A plurality of upper guide roller devices 13 and lower guide roller devices 15 are provided in the middle part in the longitudinal direction of the side frame 11 (between the traveling device 12 and the idler device 31).

[0018] A crawler (track) 14 is wound around the traveling device 12 and the idler device 31. The crawler 14 is driven by the traveling device 12 and circulates between the traveling device 12 and the idler device 31 while being guided by the upper guide roller device 13 and the lower guide roller device 15. Thereby, the lower traveling body 2 of the hydraulic excavator 1 can travel stably on a work site such as rough ground.

[0019] The two upper guide roller devices 13 are provided on the upper side of the side frame 11 at intervals in the front-rear direction. These upper guide roller devices 13 guide the crawler 14 toward the traveling device 12 and the idler device 31 while supporting the crawler 14 from below.

[0020] Next, the lower guide roller device 15 as a wheel turning device according to the first embodiment will be described with reference to FIGS. 2 to 5.

[0021] The plurality of lower guide roller devices 15 are provided at the lower end of the side frame 11 at intervals in the front-rear direction and guide the crawler 14 toward the traveling device 12 and the idler device 31. The lower guide roller device 15 includes a pair of left and right holders 16, a support shaft 18, a lower roller 20, a large-diameter O-ring 26, and a small-diameter O-ring 27.

[0022] A pair (two) of holders 16 are attached to the lower ends of the side frames 11 and face each other in the left-right direction. These two holders 16 are paired in the left-right direction and support both ends of the support shaft 18. The holder 16 is formed with an axially fitting hole 17 penetrating in the left-right direction, a pin hole 16A penetrating in the vertical direction orthogonally to the hole center of the axially fitting hole 17, and two mounting holes 16B penetrating in the vertical direction and arranged at two positions sandwiching the axially fitting hole 17. One holder 16 is fixed to the lower left plate 11C of the side frame 11 by screwing a bolt (not shown) inserted into the mounting hole 16B from below. The other holder 16 is fixed to the lower right plate 11D of the side frame 11 by screwing a bolt inserted into the mounting hole 16B from below. Further, cylindrical flange portions 16C are provided on the outer peripheral sides of the opposing end faces of the holder 16. A floating seal 22, which will be described later, is provided between the flange portion 16C of the holder 16 and the lower roller 20.

[0023] The axially fitting hole 17 formed in the holder 16 has a large-diameter fitting hole portion 17A and a small-diameter fitting hole portion 17B having a smaller hole diameter than the large-diameter fitting hole portion 17A. The large-diameter shaft portion 18A of the support shaft 18 is fitted into the large-diameter fitting hole portion 17A of the axially fitting hole 17, and the small-diameter shaft portion 18B of the support shaft 18 is fitted into the small-diameter fitting hole portion 17B of the axially fitting hole 17. Further, the boundary portion between the large-diameter fitting hole portion 17A and the small-diameter fitting hole portion 17B is a tapered portion 17C that gradually reduces in diameter from the large-diameter fitting hole portion 17A toward the small-diameter fitting hole portion 17B, and the tapered portion 18C of the support shaft 18 is fitted into this tapered portion 17C.

[0024] The support shaft 18 is fitted at both axial sides into the shaft fitting holes 17 of the pair of holders 16. The support shaft 18 is attached to the lower end of the side frame 11 via the pair of holders 16 and rotatably supports the lower roller 20. As shown in FIG. 4, the support shaft 18 is formed in a stepped cylindrical shape with both axial sides (left - right direction) having a smaller diameter. Specifically, the intermediate portion in the axial direction of the support shaft 18 is a large - diameter shaft portion 18A, and both axial sides of the support shaft 18 are smaller - diameter shaft portions 18B with a shaft diameter smaller than that of the large - diameter shaft portion 18A. That is, the outer - diameter dimension φD1 of the large - diameter shaft portion 18A is larger than the outer - diameter dimension φD2 of the smaller - diameter shaft portion 18B (φD1>φD2). The large - diameter shaft portion 18A of the support shaft 18 is fitted into the large - diameter fitting hole portion 17A of the holder 16, and the smaller - diameter shaft portion 18B of the support shaft 18 is fitted into the smaller - diameter fitting hole portion 17B of the holder 16.

[0025] The boundary portion between the large - diameter shaft portion 18A and the smaller - diameter shaft portion 18B of the support shaft 18 is a tapered portion 18C that gradually reduces in diameter from the large - diameter shaft portion 18A toward the smaller - diameter shaft portion 18B. The gradient of the tapered portion 18C is set equal to the gradient of the tapered portion 17C of the holder 16 (shaft fitting hole 17), and the tapered portion 18C of the support shaft 18 is fitted into the tapered portion 17C of the holder 16. On the smaller - diameter shaft portions 18B provided on both sides of the support shaft 18, pin holes 18D penetrating in a direction (vertical direction) orthogonal to the axial direction of the support shaft 18 are respectively formed. A retaining pin 19 is inserted through the pin hole 18D of the support shaft 18 and the pin hole 16A of the holder 16, and the support shaft 18 is supported in a retaining state with respect to the holder 16.

[0026] The lower roller 20 as a rolling element is disposed between the pair of holders 16 and is rotatably supported by the support shaft 18. The lower roller 20 is composed of a stepped cylindrical body having an axially - penetrating shaft insertion hole 20A formed at the center, and large - diameter disk - shaped flange portions 20B are integrally formed on both axial end sides. Also, at both axial ends of the lower roller 20, stepped seal mounting holes 20C having an inner - diameter dimension larger than that of the shaft insertion hole 20A are formed concentrically with the shaft insertion hole 20A. Further, an oil reservoir chamber 20D for storing lubricating oil is formed at the intermediate portion in the axial direction of the shaft insertion hole 20A (see FIG. 3).

[0027] In the shaft insertion hole 20A of the lower roller 20, cylindrical sliding bearings 21 are inserted and fitted from both axial end sides, and the large-diameter shaft portion 18A of the support shaft 18 is inserted through the shaft insertion hole 20A via the sliding bearings 21. Thereby, the lower roller 20 is rotatably supported by the support shaft 18 via the sliding bearings 21. The lower roller 20 guides the crawler belt 14 toward the traveling device 12 and the idler device 31 while restricting the lateral displacement of the crawler belt 14 by the flange portion 20B. Here, the sliding surface between the support shaft 18 and the sliding bearing 21 is always lubricated by a lubricating oil such as grease filled in the oil sump chamber 20D of the lower roller 20, and this lubricating oil is sealed in the shaft insertion hole 20A of the lower roller 20 by a floating seal 22, a large-diameter O-ring 26, and a small-diameter O-ring 27 described later.

[0028] The floating seal 22 is provided between the seal mounting hole 20C of the lower roller 20 and the flange portion 16C of the holder 16. The floating seal 22 seals the gap 23 formed between the rotating lower roller 20 and the holder 16, and prevents the lubricating oil filled in the oil sump chamber 20D of the lower roller 20 from leaking to the outside through the gap 23.

[0029] One large-diameter annular groove 24 (a total of two) is formed on each of both axial sides of the large-diameter shaft portion 18A constituting the support shaft 18. The large-diameter annular groove 24 is formed over the entire outer peripheral surface of the large-diameter shaft portion 18A. One small-diameter annular groove 25 (a total of two) is formed on each of the small-diameter shaft portions 18B constituting the support shaft 18. The small-diameter annular groove 25 is formed over the entire outer peripheral surface of the small-diameter shaft portion 18B. The outer diameter dimension (groove bottom diameter) of the groove bottom of the small-diameter annular groove 25 is formed smaller than the outer diameter dimension (groove bottom diameter) of the groove bottom of the large-diameter annular groove 24.

[0030] The large-diameter O-ring 26 is mounted in the large-diameter annular groove 24. The large-diameter O-ring 26 is formed in an annular shape using, for example, a rubber material having oil resistance and elasticity. The small-diameter O-ring 27 is mounted in the small-diameter annular groove 25. The small-diameter O-ring 27 is formed in an annular shape smaller in diameter than the large-diameter O-ring 26 using, for example, a rubber material having oil resistance and elasticity. That is, the inner diameter dimension φd1 of the large-diameter O-ring 26 is larger than the inner diameter dimension φd2 of the small-diameter O-ring 27 (φd1 > φd2).

[0031] In the present embodiment, the large-diameter O-ring 26 is formed using a material having better heat resistance than the small-diameter O-ring 27. When the hydraulic excavator 1 is traveling, due to the frictional heat between the rotating lower roller 20 and the support shaft 18, the temperature of the lubricating oil filled in the oil sump chamber 20D of the lower roller 20 rises to about 60°C to 70°C. For this reason, it is desirable that the large-diameter O-ring 26, which is constantly exposed to the lubricating oil, has better heat resistance than the small-diameter O-ring 27. On the other hand, since the small-diameter O-ring 27 is constantly exposed to the outside air, considering that the hydraulic excavator 1 operates in a cold region, the small-diameter O-ring 27 is formed using a material having better cold resistance than the large-diameter O-ring 26.

[0032] Here, as shown in FIG. 5, the inner diameter dimension φd1 of the large-diameter O-ring 26 is set larger than the outer diameter dimension φD2 of the small-diameter shaft portion 18B constituting the support shaft 18 (φd1 > φD2). Thereby, when the large-diameter O-ring 26 is mounted in the large-diameter annular groove 24 formed in the large-diameter shaft portion 18A of the support shaft 18, the large-diameter O-ring 26 can easily cross the small-diameter annular groove 25 formed in the small-diameter shaft portion 18B with a margin. Therefore, it is possible to prevent the large-diameter O-ring 26 from contacting and being damaged by the peripheral edge (edge portion) of the small-diameter annular groove 25 when crossing the small-diameter annular groove 25.

[0033] Moreover, the large-diameter O-ring 26 and the small-diameter O-ring 27 can be easily distinguished in appearance due to the difference in their diameter dimensions. Therefore, the large-diameter O-ring 26 will not be mistakenly installed in the small-diameter annular groove 25, nor will the small-diameter O-ring 27 be mistakenly installed in the large-diameter annular groove 24. Accordingly, the large-diameter O-ring 26 with excellent heat resistance can be reliably arranged on the large-diameter shaft portion 18A side exposed to the lubricating oil, and the small-diameter O-ring 27 with excellent cold resistance can be reliably arranged on the small-diameter shaft portion 18B side exposed to the outside air.

[0034] The hydraulic excavator 1 according to this embodiment has the configuration as described above. The hydraulic excavator 1 self-propels to the work site by the lower traveling body 2, and performs earthwork operations and the like using the working device 4 while rotating the upper swing body 3.

[0035] Here, when the hydraulic excavator 1 is traveling, the crawler 14 is driven to rotate by the traveling device 12, and the lower guide roller device 15, together with the upper guide roller device 13, guides the crawler 14 toward the traveling device 12 and the idler device 31.

[0036] At this time, the lower roller 20 of the lower guide roller device 15 rotates around the support shaft 18, and the sliding portion between the lower roller 20 and the support shaft 18 (large-diameter shaft portion 18A) via the sliding bearing 21 is lubricated by the lubricating oil filled in the oil sump chamber 20D. This lubricating oil is sealed in the shaft insertion hole 20A of the lower roller 20 by the large-diameter O-ring 26, the small-diameter O-ring 27, and the floating seal 22 mounted on the support shaft 18.

[0037] Here, the support shaft 18 of the lower guide roller device 15 has a large-diameter shaft portion 18A disposed at the intermediate portion in the axial direction and small-diameter shaft portions 18B disposed on both sides in the axial direction. A large-diameter O-ring 26 is mounted in the large-diameter annular groove 24 formed in the large-diameter shaft portion 18A, and a small-diameter O-ring 27 is mounted in the small-diameter annular groove 25 formed in the small-diameter shaft portion 18B. And the inner diameter dimension φd1 of the large-diameter O-ring 26 is set larger than the outer diameter dimension φD2 of the small-diameter shaft portion 18B (φd1 > φD2).

[0038] Therefore, when the large-diameter O-ring 26 is mounted on the large-diameter annular groove 24, the large-diameter O-ring 26 can smoothly cross the small-diameter annular groove 25 formed in the small-diameter shaft portion 18B with a margin, and the large-diameter O-ring 26 will not contact and be damaged by the peripheral portion of the small-diameter annular groove 25. As a result, the service life of the large-diameter O-ring 26 can be extended, and the sealing performance of the large-diameter O-ring 26 against the lubricating oil can be improved.

[0039] Moreover, since the large-diameter O-ring 26 and the small-diameter O-ring 27 have different diameter dimensions, they are easily distinguishable in appearance. Therefore, the operation error when assembling the large-diameter O-ring 26 and the small-diameter O-ring 27 can be reduced, and the large-diameter O-ring 26 can be surely mounted on the large-diameter annular groove 24, and the small-diameter O-ring 27 can be surely mounted on the small-diameter annular groove 25. Thereby, the large-diameter O-ring 26 with excellent heat resistance can be surely arranged on the side of the large-diameter shaft portion 18A exposed to the lubricating oil, and the small-diameter O-ring 27 with excellent cold resistance can be surely arranged on the side of the small-diameter shaft portion 18B exposed to the outside air. As a result, the temperature characteristics of the large-diameter O-ring 26 and the small-diameter O-ring 27 can be effectively utilized, and the sealing performance by these large-diameter O-ring 26 and small-diameter O-ring 27 can be further improved.

[0040] Furthermore, at the boundary between the large-diameter shaft portion 18A and the small-diameter shaft portion 18B of the support shaft 18, a tapered portion 18C that gradually reduces in diameter from the large-diameter shaft portion 18A toward the small-diameter shaft portion 18B is provided. Thereby, since there is no sharp edge portion at the boundary between the large-diameter shaft portion 18A and the small-diameter shaft portion 18B, the large-diameter O-ring 26 can smoothly move from the small-diameter shaft portion 18B to the large-diameter shaft portion 18A along the tapered portion 18C. As a result, the large-diameter O-ring 26 can be mounted on the large-diameter annular groove 24 without being damaged, and its service life can be extended.

[0041] Thus, in the lower guide roller device 15 of the hydraulic excavator 1 according to the present embodiment, the support shaft 18 has a large-diameter shaft portion 18A located at the intermediate portion in the axial direction and small-diameter shaft portions 18B located on both sides in the axial direction and having a smaller shaft diameter than the large-diameter shaft portion 18A. The shaft fitting holes 17 of the pair of holders 16 are composed of a large-diameter fitting hole portion 17A into which the large-diameter shaft portion 18A is fitted and a small-diameter fitting hole portion 17B having a smaller hole diameter than the large-diameter fitting hole portion 17A and into which the small-diameter shaft portion 18B is fitted. An outer circumference of the large-diameter shaft portion 18A is provided with a large-diameter annular groove 24 extending over the entire circumference, and an outer circumference of the small-diameter shaft portion 18B is provided with a small-diameter annular groove 25 smaller in diameter than the large-diameter annular groove 24 extending over the entire circumference. The O-ring is composed of a large-diameter O-ring 26 attached to the large-diameter annular groove 24 and a small-diameter O-ring 27 attached to the small-diameter annular groove 25.

[0042] According to this configuration, since the large-diameter O-ring 26 is attached to the large-diameter annular groove 24, when the large-diameter O-ring 26 gets over the small-diameter annular groove 25 formed in the small-diameter shaft portion 18B, it is possible to suppress the large-diameter O-ring 26 from contacting and being damaged by the peripheral edge portion (edge portion) of the small-diameter annular groove 25. As a result, the sealing performance of the large-diameter O-ring 26 that seals the lubricating oil in the shaft insertion hole 20A of the lower roller 20 can be improved. Moreover, since the large-diameter O-ring 26 and the small-diameter O-ring 27 having different diameter dimensions are easily distinguishable in appearance, the large-diameter O-ring 26 can be surely attached to the large-diameter annular groove 24 and the small-diameter O-ring 27 can be surely attached to the small-diameter annular groove 25.

[0043] In the embodiment, the inner diameter dimension φd1 of the large-diameter O-ring 26 is set to be larger than the outer diameter dimension φD2 of the small-diameter shaft portion 18B. According to this configuration, when the large-diameter O-ring 26 is attached to the large-diameter annular groove 24, the large-diameter O-ring 26 can get over the small-diameter annular groove 25 formed in the small-diameter shaft portion 18B with a margin. As a result, it is possible to surely prevent the large-diameter O-ring 26 from contacting and being damaged by the peripheral edge portion of the small-diameter annular groove 25, and the service life of the large-diameter O-ring 26 can be extended.

[0044] In the embodiment, at the boundary between the large-diameter shaft portion 18A and the small-diameter shaft portion 18B, a tapered portion 18C that gradually reduces in diameter from the large-diameter shaft portion 18A toward the small-diameter shaft portion 18B is provided. According to this configuration, since there is no sharp edge portion at the boundary between the large-diameter shaft portion 18A and the small-diameter shaft portion 18B, the large-diameter O-ring 26 can smoothly move from the small-diameter shaft portion 18B to the large-diameter shaft portion 18A along the tapered portion 18C. As a result, the large-diameter O-ring 26 can be attached to the large-diameter annular groove 24 without being damaged, and its lifespan can be extended.

[0045] In the embodiment, the large-diameter O-ring 26 is formed using a material having better heat resistance than the small-diameter O-ring 27. According to this configuration, even if the temperature of the lubricating oil filled in the oil sump chamber 20D of the lower roller 20 rises due to the frictional heat between the rotating lower roller 20 and the support shaft 18, the lifespan of the large-diameter O-ring 26 that is constantly exposed to the lubricating oil can be extended, and its sealing performance can be improved.

[0046] Next, FIG. 6 shows a second embodiment of the present invention. In this embodiment, an idler device of the hydraulic excavator 1 is illustrated as the idler device. In this embodiment, the same components as those in the above-described first embodiment are denoted by the same reference numerals, and the description thereof is omitted.

[0047] In FIG. 6, an idler device 31 as the idler device is attached to an idler bracket 32 provided on the other end side in the length direction of the side frame 11. The idler device 31 supports the crawler belt 14 so as to be able to perform a circumferential movement on the other end side of the side frame 11, and adjusts the tension of the crawler belt 14 with the traveling device 12.

[0048] The idler device 31 is configured to include a pair of holders 33, a support shaft 35, an idler 36, a large-diameter O-ring 40, and a small-diameter O-ring 41, similar to the lower guide roller device 15 according to the first embodiment.

[0049] The pair of holders 33 are arranged to be movable in the front-rear direction along the left and right guide members 32A provided on the idler bracket 32, and face each other in the left-right direction. The pair of holders 33 are each formed with a shaft fitting hole 34 penetrating in the left-right direction. The shaft fitting hole 34 has a large-diameter fitting hole portion 34A, a small-diameter fitting hole portion 34B, and a tapered portion 34C that gradually reduces in diameter from the large-diameter fitting hole portion 34A toward the small-diameter fitting hole portion 34B.

[0050] The support shaft 35 has a large-diameter shaft portion 35A located at the intermediate portion in the axial direction, small-diameter shaft portions 35B located on both sides in the axial direction, and a tapered portion 35C that gradually reduces in diameter from the large-diameter shaft portion 35A toward the small-diameter shaft portions 35B. The large-diameter shaft portion 35A of the support shaft 35 is fitted into the large-diameter fitting hole portion 34A of the holder 33, the small-diameter shaft portion 35B is fitted into the small-diameter fitting hole portion 34B of the holder 33, and the tapered portion 35C is fitted into the tapered portion 35C of the holder 33.

[0051] The idler 36 as a rolling body is arranged between the pair of holders 33 and is rotatably supported by the support shaft 35. A shaft insertion hole 36A penetrating in the axial direction is formed at the center of the idler 36, and the large-diameter shaft portion 35A of the support shaft 35 is inserted into the shaft insertion hole 36A via a sliding bearing 37. Thereby, the idler 36 is rotatably supported by the support shaft 35 via the sliding bearing 37. Further, an oil reservoir chamber 36B for storing lubricating oil is formed at the intermediate portion in the axial direction of the shaft insertion hole 36A. The sliding surface between the support shaft 35 and the sliding bearing 37 is always lubricated by the lubricating oil filled in the oil reservoir chamber 36B.

[0052] On both axial sides of the large-diameter shaft portion 35A that constitutes the support shaft 35, one large-diameter annular groove 38 is formed respectively. One small-diameter annular groove 39 is formed respectively in the small-diameter shaft portion 35B that constitutes the support shaft 35. The large-diameter O-ring 40 is mounted in the large-diameter annular groove 38, and the small-diameter O-ring 41 is mounted in the small-diameter annular groove 39. The large-diameter O-ring 40 is formed using a material with better heat resistance than the small-diameter O-ring 41, and the small-diameter O-ring 41 is formed using a material with better cold resistance than the large-diameter O-ring 40. The inner diameter dimension of the large-diameter O-ring 40 is set larger than the outer diameter dimension of the small-diameter shaft portion 35B that constitutes the support shaft 35.

[0053] The idler device 31 according to the second embodiment has the configuration as described above. Also in this embodiment, similar to the lower guide roller device 15 according to the first embodiment, the inner diameter dimension of the large-diameter O-ring 40 is set larger than the outer diameter dimension of the small-diameter shaft portion 35B. Thereby, when mounting the large-diameter O-ring 40 in the large-diameter annular groove 38 of the support shaft 35, it is possible to suppress the large-diameter O-ring 40 from contacting and being damaged by the peripheral edge of the small-diameter annular groove 39. As a result, the service life of the large-diameter O-ring 40 can be extended, and the sealing performance of the large-diameter O-ring 40 against the lubricating oil can be improved. Other operational effects of the idler device 31 are the same as those of the lower guide roller device 15 according to the first embodiment.

[0054] In the embodiment, the lower guide roller device 15 and the idler device 31 used in the crawler-type hydraulic excavator 1 are exemplified as the idler devices. However, the present invention is not limited to this, and for example, it can be widely applied to the idler devices of track-mounted vehicles such as crawler-type hydraulic cranes and crawler-type aerial work vehicles.

Description of Signs

[0055] 2 Lower Traveling Body (Vehicle Body) 3 Upper Swing Body (Vehicle Body) 16, 33 Holder 17, 34 Shaft Fitting Hole 17A, 34A Large-Diameter Fitting Hole Portion (Large-Diameter Fitting Hole) 17B, 34B Small-Diameter Fitting Hole Portion (Small-Diameter Fitting Hole) 18, 35 Support Shaft 18A, 35A Large-diameter Shaft Portion 18B, 35B Small-diameter Shaft Portion 18C, 35C Taper Portion 20 Lower Roller (Rotating Body) 20A, 36A Shaft Insertion Hole 24, 38 Large-diameter Annular Groove 25, 39 Small-diameter Annular Groove 26, 40 Large-diameter O-ring 27, 41 Small-diameter O-ring 36 Idler (Rotating Body)

Claims

1. A pair of holders attached facing the body of a construction machine, Axial fitting holes respectively provided in the pair of holders, A support shaft with both ends in the axial direction fitted into the axial fitting holes of the pair of holders, A rotating wheel body having an axial insertion hole through which the support shaft is inserted and being rotatably supported by the support shaft, In a rotating wheel device of a construction machine comprising O-rings respectively provided between the support shaft and the pair of holders and sealing lubricating oil in the axial insertion hole of the rotating wheel body, The support shaft has a large-diameter shaft portion located in the middle part in the axial direction and small-diameter shaft portions located on both sides in the axial direction and having a smaller shaft diameter than the large-diameter shaft portion, The axial fitting holes of the pair of holders are constituted by a large-diameter fitting hole into which the large-diameter shaft portion is fitted and a small-diameter fitting hole having a smaller hole diameter than the large-diameter fitting hole and into which the small-diameter shaft portion is fitted, An outer circumference of the large-diameter shaft portion is provided with a large-diameter annular groove extending over the entire circumference, An outer circumference of the small-diameter shaft portion is provided with a small-diameter annular groove having a smaller diameter than the large-diameter annular groove and extending over the entire circumference, The O-ring is constituted by a large-diameter O-ring attached to the large-diameter annular groove and a small-diameter O-ring attached to the small-diameter annular groove, which is a feature of the rotating wheel device of a construction machine.

2. The rotating wheel device of a construction machine according to Claim 1, wherein an inner diameter dimension of the large-diameter O-ring is set to be larger than an outer diameter dimension of the small-diameter shaft portion.

3. The rotating wheel device of a construction machine according to Claim 1, wherein a tapered portion that gradually reduces in diameter from the large-diameter shaft portion toward the small-diameter shaft portion is provided at a boundary portion between the large-diameter shaft portion and the small-diameter shaft portion.

4. The rotating wheel device of a construction machine according to Claim 1, wherein the large-diameter O-ring is formed using a material having better heat resistance than the small-diameter O-ring.

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