JP7709936B2 - Roller device for construction machinery - Google Patents

Description

This disclosure relates to a roller device mounted on a construction machine such as a hydraulic excavator.

Hydraulic excavators, which are representative of construction machinery, are equipped with a crawler-type undercarriage for stable travel on rough ground. The crawler-type undercarriage is composed of a track frame with left and right side frames, a travel device (sprocket) provided at one end of the side frame, an idler device provided at the other end of the side frame, a number of upper and lower rollers provided on the side frame and positioned between the travel device and the idler device, and a track wound around the travel device and the idler device. The track is driven by the travel device and moves around a fixed track by being guided by the idler device and the upper and lower rollers.

The lower roller, which is provided on the lower running body, is rotatably supported via a support shaft by a pair of holders provided on the underside of the side frame. The lower roller is provided with a shaft insertion hole through which the support shaft is inserted, and this shaft insertion hole is filled with a lubricating oil such as grease that lubricates the sliding part between the lower roller and the support shaft. An O-ring is attached to each of the axial ends of the support shaft that fits into the pair of holders. Therefore, when both ends of the support shaft are fitted into the holders, the O-ring seals the fitting part between the holder and the support shaft, and seals the lubricating oil in the shaft insertion hole of the lower roller.

Here, a lower roller is proposed in which two O-rings are attached to each of the axial ends of the support shaft (four in total). In this conventional technology, an O-ring with excellent cold resistance is placed on the axial end side of the support shaft, which is exposed to the outside air in cold regions, and an inner O-ring with excellent heat resistance is placed on the inside of the support shaft, which is exposed to frictional heat caused by sliding with the lower roller. The O-ring on the axial end side mainly prevents foreign matter such as soil and sand from entering the fitting between the holder and the support shaft. The inner O-ring mainly prevents lubricating oil filled in the shaft insertion hole of the lower roller from leaking to the outside. In this way, 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).

JP 2015-20608 A

Here, the shaft end side O-ring and the inner O-ring according to the conventional technology are arranged adjacent to the outer peripheral surface of a support shaft having the same outer diameter. That is, the outer peripheral surface of the support shaft is formed with a shaft end side annular groove located on the shaft end side and an inner annular groove located on the inside (center side) of the support shaft, and the shaft end side O-ring with excellent cold resistance is fitted into the shaft end side annular groove, and the inner O-ring with excellent heat resistance is fitted into the inner annular groove.

However, the inner O-ring needs to be fitted into the inner annular groove after climbing over the shaft end side annular groove. This causes a problem in that when climbing over the shaft end side annular groove, the inner O-ring comes into contact with the periphery (edge) of the shaft end side annular groove, resulting in damage to the inner O-ring.

In addition, because 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, it is possible to mistakenly install the inner O-ring, which has excellent heat resistance, in the shaft end side annular groove, or the shaft end side O-ring, which has excellent cold resistance, in the inner annular groove. This causes the temperature characteristics of the inner O-ring and shaft end side O-ring to not function effectively, resulting in a shortened lifespan of each.

The object of the present invention is to provide a roller device for construction machinery that can improve the sealing performance of the O-ring that seals the lubricating oil inside the shaft insertion hole of the roller body.

The present invention relates to a roller device for a construction machine, the roller device comprising: a pair of holders attached to the vehicle body of the construction machine in opposition to each other; a shaft fitting hole provided in each of the pair of holders; a support shaft having both axial ends fitted into the shaft fitting hole of the pair of holders; a roller body having a shaft insertion hole through which the support shaft is inserted and rotatably supported on the support shaft; and O-rings provided between the support shaft and the pair of holders for sealing lubricating oil in the shaft insertion hole of the roller body. The support shaft has a large diameter shaft portion located in the middle of the axial direction and large diameter shaft portions located on both sides of the axial direction. The shaft fitting hole of the pair of holders is composed of a large diameter fitting hole into which the large diameter shaft portion fits and a small diameter fitting hole having a hole diameter smaller than the large diameter fitting hole into which the small diameter shaft portion fits, a large diameter annular groove is provided around the entire circumference of the large diameter shaft portion, a small diameter annular groove smaller than the large diameter annular groove is provided around the entire circumference of the small diameter shaft portion, and 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.

According to the present invention, when the large-diameter O-ring climbs over the small-diameter annular groove to be fitted into the large-diameter annular groove, it is possible to prevent the large-diameter O-ring from contacting the peripheral portion of the small-diameter annular groove. This allows the large-diameter O-ring to be fitted into the large-diameter annular groove without being damaged, improving the sealing performance.

1 is a left side view showing a hydraulic excavator to which a roller device according to an embodiment of the present invention is applied. FIG. 2 is a perspective view showing a lower guide roller device according to the first embodiment. 3 is a cross-sectional view of the lower guide roller device as viewed from the direction of arrows III-III in FIG. 1. FIG. 2 is a perspective view showing a support shaft, a small-diameter annular groove, a large-diameter annular groove, a small-diameter O-ring, and a large-diameter O-ring. 4 is an enlarged view showing the outer diameter dimensions of the small diameter shaft portion and the large diameter shaft portion of the support shaft and the inner diameter dimensions of the small diameter O-ring and the large diameter O-ring. FIG. 6 is a cross-sectional view of an idler device according to a second embodiment, taken along the direction of arrows VI-VI in FIG. 1.

The following describes in detail an embodiment of a construction machine roller device according to the present invention, as applied to a hydraulic excavator, with reference to the accompanying drawings. In the embodiment, the travel direction of the hydraulic excavator is defined as the front-rear direction, and the direction perpendicular to the travel direction is defined as the left-right direction.

Figures 1 to 5 show a first embodiment of the present invention. In Figure 1, a hydraulic excavator 1 includes a self-propelled crawler-type lower traveling body 2, an upper rotating body 3 rotatably mounted on the lower traveling body 2, and a working device 4 provided in front of the upper rotating body 3. The lower traveling body 2 and the upper rotating body 3 form the body of the hydraulic excavator 1. The hydraulic excavator 1 performs work such as excavating soil and sand using the working device 4.

The upper rotating body 3 is composed of a rotating frame 5 serving as a base, a cab 6 mounted on the left front side of the rotating frame 5, a counterweight 7 attached to the rear end of the rotating frame 5, and an exterior cover 8 attached to the front side of the counterweight 7. The cab 6 defines the driver's compartment in which the operator sits, and inside the cab 6 are a driver's seat, travel levers/pedals, and operating levers (none of which are shown). The counterweight 7 maintains the weight balance with the working device 4 attached to the front side of the rotating frame 5. The exterior cover 8 covers the onboard equipment (none of which are shown) such as the prime mover, hydraulic pump, and control valve mounted on the rotating frame 5.

The lower running body 2 is equipped with a truck frame 9 that serves as a base. The truck frame 9 has a center frame 10 located in the center in the left-right direction, and a pair of left and right side frames 11 (only the left side is shown) arranged on either side of the center frame 10, 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 plate 11A and a right plate 11B that face each other in the left-right direction at a certain distance, and an upper plate (not shown) that connects the upper ends of the left plate 11A and the right plate 11B, and is formed as a frame body having a U-shaped cross-sectional shape with an open lower end. A left lower plate 11C extending in the front-rear direction is welded to the lower end of the left plate 11A, and a right lower plate 11D extending in the front-rear direction is welded to the lower end of the right plate 11B.

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

A track (crawler) 14 is wound around the traveling device 12 and the idler device 31. The track 14 is driven by the traveling device 12 and moves around 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. This allows the lower traveling body 2 of the hydraulic excavator 1 to travel stably on a work site such as uneven ground.

The two upper guide roller devices 13 are spaced apart in the front-rear direction and are provided on the upper side of the side frame 11. These upper guide roller devices 13 support the crawler belt 14 from below and guide it toward the running device 12 and the idler device 31.

Next, the lower guide roller device 15 as a roller device according to the first embodiment will be described with reference to Figures 2 to 5.

The lower guide roller devices 15 are provided at the lower ends of the side frames 11 at intervals in the front-rear direction, and guide the crawler belt 14 toward the traveling device 12 and the idler device 31. The lower guide roller devices 15 are composed of 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.

A pair (two pieces) of holders 16 are attached to the lower end of the side frame 11 and face each other in the left-right direction. The pair of holders 16 form a pair in the left-right direction and support both ends of the support shaft 18. The holder 16 has a shaft fitting hole 17 (described later) that penetrates in the left-right direction, a pin hole 16A that penetrates in the up-down direction perpendicular to the center of the shaft fitting hole 17, and two mounting holes 16B that are arranged on two sides of the shaft fitting hole 17 and penetrate in the up-down direction. One of the holders 16 is fixed to the left lower plate 11C by screwing a bolt (not shown) inserted from below into the mounting hole 16B into the left lower plate 11C of the side frame 11. The other holder 16 is fixed to the right lower plate 11D by screwing a bolt inserted from below into the mounting hole 16B into the right lower plate 11D of the side frame 11. Additionally, a cylindrical flange 16C is provided on the outer periphery of the opposing end faces of the holder 16. A floating seal 22, which will be described later, is provided between the flange 16C of the holder 16 and the lower roller 20.

The shaft fitting hole 17 formed in the holder 16 has a large diameter fitting hole portion 17A and a small diameter fitting hole portion 17B with a smaller hole diameter than the large diameter fitting hole portion 17A. The large diameter fitting hole portion 17A of the shaft fitting hole 17 is fitted with the large diameter shaft portion 18A of the support shaft 18, and the small diameter fitting hole portion 17B of the shaft fitting hole 17 is fitted with the small diameter shaft portion 18B of the support shaft 18. The boundary 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 to the small diameter fitting hole portion 17B, and the tapered portion 17C of the support shaft 18 is fitted into this tapered portion 17C.

The support shaft 18 is fitted into the shaft fitting holes 17 of the pair of holders 16 on both sides in the axial direction. 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 a small diameter on both sides in the axial direction (left and right direction). Specifically, the axial middle part of the support shaft 18 is a large diameter shaft part 18A, and both sides of the support shaft 18 in the axial direction are small diameter shaft parts 18B whose shaft diameter is smaller than that of the large diameter shaft part 18A. That is, the outer diameter dimension φD1 of the large diameter shaft part 18A is larger than the outer diameter dimension φD2 of the small diameter shaft part 18B (φD1>φD2). The large diameter shaft portion 18A of the support shaft 18 fits into the large diameter fitting hole portion 17A of the holder 16, and the small diameter shaft portion 18B of the support shaft 18 fits into the small diameter fitting hole portion 17B of the holder 16.

The boundary between the large diameter shaft portion 18A and the small 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 to the small 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. The small diameter shaft portions 18B provided on both sides of the support shaft 18 each have a pin hole 18D that penetrates in a direction perpendicular to the axial direction of the support shaft 18 (up and down direction). A rotation stop pin 19 is inserted into 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 rotation-stopped state relative to the holder 16.

The lower roller 20, which serves as a roller body, is disposed between a pair of holders 16 and rotatably supported by a support shaft 18. The lower roller 20 is a stepped cylinder with a shaft insertion hole 20A formed axially through its center, and large-diameter disk-shaped flanges 20B are integrally formed on both axial ends. In addition, stepped seal mounting holes 20C with an inner diameter larger than the shaft insertion hole 20A are formed concentrically with the shaft insertion hole 20A on both axial ends of the lower roller 20. Furthermore, an oil reservoir 20D for storing lubricating oil is formed in the axial middle of the shaft insertion hole 20A (see FIG. 3).

Cylindrical plain bearings 21 are inserted into the shaft insertion hole 20A of the lower roller 20 from both axial ends, and the large diameter shaft portion 18A of the support shaft 18 is inserted into the shaft insertion hole 20A via the plain bearing 21. As a result, the lower roller 20 is rotatably supported by the support shaft 18 via the plain bearing 21. The lower roller 20 guides the track 14 toward the traveling device 12 and the idler device 31 while restricting the left-right positional deviation of the track 14 with the flange portion 20B. Here, the sliding surface between the support shaft 18 and the plain bearing 21 is constantly lubricated by lubricating oil such as grease filled in the oil reservoir 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 the floating seal 22, large diameter O-ring 26, and small diameter O-ring 27 described later.

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

The large diameter annular grooves 24 are formed on both sides of the large diameter shaft portion 18A constituting the support shaft 18 in the axial direction (two in total). The large diameter annular grooves 24 are formed all around the outer circumferential surface of the large diameter shaft portion 18A. The small diameter annular grooves 25 are formed on both sides of the small diameter shaft portion 18B constituting the support shaft 18 (two in total). The small diameter annular grooves 25 are formed all around the outer circumferential 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 smaller than the outer diameter dimension (groove bottom diameter) of the groove bottom of the large diameter annular groove 24.

The large diameter O-ring 26 is fitted into the large diameter annular groove 24. The large diameter O-ring 26 is formed into an annular shape using, for example, an oil-resistant, elastic rubber material. The small diameter O-ring 27 is fitted into the small diameter annular groove 25. The small diameter O-ring 27 is formed into an annular shape with a smaller diameter than the large diameter O-ring 26 using, for example, an oil-resistant, elastic rubber material. 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).

In this embodiment, the large diameter O-ring 26 is formed using a material with better heat resistance than the small diameter O-ring 27. When the hydraulic excavator 1 is traveling, the temperature of the lubricating oil filled in the oil reservoir 20D of the lower roller 20 rises to about 60°C to 70°C due to frictional heat between the rotating lower roller 20 and the support shaft 18. For this reason, it is desirable that the large diameter O-ring 26, which is always 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 always exposed to the outside air, the small diameter O-ring 27 is formed using a material with better cold resistance than the large diameter O-ring 26, taking into consideration that the hydraulic excavator 1 will be operating in a cold region.

As shown in FIG. 5, 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 that constitutes the support shaft 18 (φd1>φD2). This allows the large diameter O-ring 26 to easily overcome the small diameter annular groove 25 formed in the small diameter shaft portion 18B when the large diameter O-ring 26 is attached to the large diameter annular groove 24 formed in the large diameter shaft portion 18A of the support shaft 18. This prevents the large diameter O-ring 26 from coming into contact with the peripheral portion (edge portion) of the small diameter annular groove 25 and being damaged when it overcomes the small diameter annular groove 25.

In addition, the large diameter O-ring 26 and the small diameter O-ring 27 can be easily distinguished from each other visually due to the difference in diameter. This prevents the large diameter O-ring 26 from being mistakenly installed in the small diameter annular groove 25, and the small diameter O-ring 27 from being mistakenly installed in the large diameter annular groove 24. This allows the large diameter O-ring 26, which has excellent heat resistance, to be reliably positioned on the large diameter shaft portion 18A side exposed to the lubricating oil, and the small diameter O-ring 27, which has excellent cold resistance, to be reliably positioned on the small diameter shaft portion 18B side exposed to the outside air.

The hydraulic excavator 1 according to this embodiment has the above-mentioned configuration, and the hydraulic excavator 1 is self-propelled at the work site by the lower traveling body 2, and performs work such as excavating soil and sand using the working device 4 while rotating the upper rotating body 3.

When the hydraulic excavator 1 travels, the track 14 is driven to rotate by the travel device 12, and the lower guide roller device 15, together with the upper guide roller device 13, guides the track 14 toward the travel device 12 and the idler device 31.

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 slide bearing 21 is lubricated by the lubricating oil filled in the oil reservoir 20D. This lubricating oil is sealed in the shaft insertion hole 20A of the lower roller 20 by the large diameter O-ring 26, small diameter O-ring 27, and floating seal 22 attached to the support shaft 18.

Here, the support shaft 18 of the lower guide roller device 15 has a large diameter shaft portion 18A located in the middle in the axial direction and a small diameter shaft portion 18B located on both sides in the axial direction, and a large diameter O-ring 26 is fitted in the large diameter annular groove 24 formed in the large diameter shaft portion 18A, and a small diameter O-ring 27 is fitted in the small diameter annular groove 25 formed in the small diameter shaft portion 18B. 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 (φd1>φD2).

For this reason, when the large diameter O-ring 26 is fitted into the large diameter annular groove 24, the large diameter O-ring 26 can easily overcome the small diameter annular groove 25 formed in the small diameter shaft portion 18B, and the large diameter O-ring 26 does not come into contact with the peripheral portion of the small diameter annular groove 25 and is not damaged. As a result, the life of the large diameter O-ring 26 can be extended, and the sealing ability of the large diameter O-ring 26 against lubricating oil can be improved.

Moreover, the large diameter O-ring 26 and the small diameter O-ring 27 have different diameters, so they are easily distinguishable from each other. This reduces the chance of mistakes when assembling the large diameter O-ring 26 and the small diameter O-ring 27, and the large diameter O-ring 26 can be reliably fitted into the large diameter annular groove 24 and the small diameter O-ring 27 can be reliably fitted into the small diameter annular groove 25. This allows the large diameter O-ring 26, which has excellent heat resistance, to be reliably positioned on the large diameter shaft portion 18A side exposed to the lubricating oil, and the small diameter O-ring 27, which has excellent cold resistance, to be reliably positioned on the small diameter shaft portion 18B side 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 of the large diameter O-ring 26 and the small diameter O-ring 27 can be further improved.

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 is provided that gradually reduces in diameter from the large diameter shaft portion 18A toward the small diameter shaft portion 18B. As a result, there are no sharp edges at the boundary between the large diameter shaft portion 18A and the small diameter shaft portion 18B, so the large diameter O-ring 26 can move smoothly 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.

Thus, in this embodiment, in the lower guide roller device 15 of the hydraulic excavator 1, the support shaft 18 has a large diameter shaft portion 18A located in the middle in the axial direction and a small diameter shaft portion 18B located on both sides in the axial direction and having a shaft diameter smaller than that of the large diameter shaft portion 18A, the shaft fitting hole 17 of the pair of holders 16 is composed of a large diameter fitting hole portion 17A into which the large diameter shaft portion 18A fits and a small diameter fitting hole portion 17B having a hole diameter smaller than that of the large diameter fitting hole portion 17A into which the small diameter shaft portion 18B fits, a large diameter annular groove 24 is provided around the entire circumference of the outer periphery of the large diameter shaft portion 18A, a small diameter annular groove 25 having a diameter smaller than that of the large diameter annular groove 24 is provided around the entire circumference of the outer periphery of the small diameter shaft portion 18B, and 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.

According to this configuration, since the large diameter O-ring 26 is fitted into the large diameter annular groove 24, when the large diameter O-ring 26 rides over the small diameter annular groove 25 formed in the small diameter shaft portion 18B, the large diameter O-ring 26 can be prevented from contacting and being damaged by the peripheral 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, which have different diameter dimensions, are easily distinguishable from each other on the outside, the large diameter O-ring 26 can be reliably fitted into the large diameter annular groove 24, and the small diameter O-ring 27 can be reliably fitted into the small diameter annular groove 25.

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. With 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 easily overcome the small diameter annular groove 25 formed in the small diameter shaft portion 18B. As a result, it is possible to reliably prevent the large diameter O-ring 26 from coming into contact with the peripheral portion of the small diameter annular groove 25 and being damaged, and the life of the large diameter O-ring 26 can be extended.

In the embodiment, a tapered portion 18C is provided at the boundary between the large diameter shaft portion 18A and the small diameter shaft portion 18B, the diameter of which gradually decreases from the large diameter shaft portion 18A toward the small diameter shaft portion 18B. With this configuration, there is no sharp edge at the boundary between the large diameter shaft portion 18A and the small diameter shaft portion 18B, so the large diameter O-ring 26 can move smoothly 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.

In this embodiment, the large diameter O-ring 26 is formed using a material with better heat resistance than the small diameter O-ring 27. With this configuration, even if the temperature of the lubricating oil filled in the oil reservoir 20D of the lower roller 20 rises due to frictional heat between the rotating lower roller 20 and the support shaft 18, the life of the large diameter O-ring 26, which is constantly exposed to the lubricating oil, can be extended and its sealing performance can be improved.

Next, FIG. 6 shows a second embodiment of the present invention, in which an idler device of a hydraulic excavator 1 is exemplified as a roller device. Note that in this embodiment, the same components as those in the first embodiment described above are given the same reference numerals, and their description will be omitted.

In FIG. 6, the idler device 31, which serves as a roller device, is attached to an idler bracket 32 provided on the other end of the side frame 11 in the longitudinal direction. The idler device 31 supports the track 14 at the other end of the side frame 11 so that it can move around, and adjusts the tension of the track 14 between the running gear 12 and the idler device 31.

The idler device 31, like the lower guide roller device 15 of the first embodiment, 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.

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. Each of the pair of holders 33 has a shaft fitting hole 34 that penetrates 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 to the small diameter fitting hole portion 34B.

The support shaft 35 has a large diameter shaft portion 35A located in the middle 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 to the small diameter shaft portion 35B. The large diameter shaft portion 35A of the support shaft 35 fits into the large diameter fitting hole portion 34A of the holder 33, the small diameter shaft portion 35B fits into the small diameter fitting hole portion 34B of the holder 33, and the tapered portion 35C fits into the tapered portion 35C of the holder 33.

The idler 36, which serves as a roller body, is disposed between a pair of holders 33 and rotatably supported by the support shaft 35. A shaft insertion hole 36A is formed in the center of the idler 36, penetrating in the axial direction, and the large-diameter shaft portion 35A of the support shaft 35 is inserted into the shaft insertion hole 36A via a plain bearing 37. This allows the idler 36 to be rotatably supported by the support shaft 35 via the plain bearing 37. An oil reservoir 36B that stores lubricating oil is formed in the axial middle portion of the shaft insertion hole 36A. The sliding surfaces of the support shaft 35 and the plain bearing 37 are constantly lubricated by the lubricating oil filled in the oil reservoir 36B.

A large diameter annular groove 38 is formed on each side of the axial direction of the large diameter shaft portion 35A constituting the support shaft 35. A small diameter annular groove 39 is formed on each small diameter shaft portion 35B constituting the support shaft 35. A large diameter O-ring 40 is fitted in the large diameter annular groove 38, and a small diameter O-ring 41 is fitted in the small diameter annular groove 39. The large diameter O-ring 40 is made of a material with better heat resistance than the small diameter O-ring 41, and the small diameter O-ring 41 is made of 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 to be larger than the outer diameter dimension of the small diameter shaft portion 35B constituting the support shaft 35.

The idler device 31 according to the second embodiment has the above-mentioned configuration, and in this embodiment, as in the lower guide roller device 15 according to the first embodiment, the inner diameter dimension of the large diameter O-ring 40 is set to be larger than the outer diameter dimension of the small diameter shaft portion 35B. This makes it possible to prevent the large diameter O-ring 40 from contacting the peripheral portion of the small diameter annular groove 39 and being damaged when the large diameter O-ring 40 is attached to the large diameter annular groove 38 of the support shaft 35. As a result, the life of the large diameter O-ring 40 can be extended, and the sealing ability of the large diameter O-ring 40 against the lubricating oil can be improved. Other effects of the idler device 31 are also the same as those of the lower guide roller device 15 according to the first embodiment.

In the embodiment, the lower guide roller device 15 and the idler device 31 used in the crawler hydraulic excavator 1 are exemplified as the roller device. However, the present invention is not limited to this, and can be widely applied to roller devices of tracked vehicles such as crawler hydraulic cranes and crawler aerial work vehicles.

2. Undercarriage (car body)
3. Upper rotating body (car 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 (small diameter fitting hole)
18, 35 Support shaft 18A, 35A Large diameter shaft portion 18B, 35B Small diameter shaft portion 18C, 35C Tapered portion 20 Lower roller (rolling 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 (rolling body)

Claims (4)

A pair of holders attached to a vehicle body of the construction machine so as to face each other;
a shaft fitting hole provided in each of the pair of holders;
a support shaft having both axial ends fitted in the shaft fitting holes of the pair of holders;
a roller body having a shaft insertion hole through which the support shaft is inserted and rotatably supported by the support shaft;
a pair of O-rings provided between the support shaft and the pair of holders, the O-rings sealing the lubricating oil in the shaft insertion hole of the roller body,
The support shaft has a large diameter shaft portion located in an axially intermediate portion and small diameter shaft portions located on both sides in the axial direction and having a shaft diameter smaller than that of the large diameter shaft portions,
the shaft fitting holes of the pair of holders are configured with a large diameter fitting hole into which the large diameter shaft portion is fitted, and a small diameter fitting hole having a hole diameter smaller than that of the large diameter fitting hole into which the small diameter shaft portion is fitted,
A large diameter annular groove is provided around the entire outer periphery of the large diameter shaft portion,
A small diameter annular groove having a smaller diameter than the large diameter annular groove is provided around the entire circumference of the small diameter shaft portion,
A roller device for a construction machine, characterized in that the O-ring is composed of a large diameter O-ring mounted in the large diameter annular groove and a small diameter O-ring mounted in the small diameter annular groove. The roller device for a construction machine according to claim 1, characterized in that the inner diameter of the large diameter O-ring is set to be larger than the outer diameter of the small diameter shaft portion. The roller device for a construction machine according to claim 1, characterized in that a tapered section is provided at the boundary between the large diameter shaft section and the small diameter shaft section, the diameter of which gradually decreases from the large diameter shaft section toward the small diameter shaft section. The roller device for a construction machine according to claim 1, characterized in that the large diameter O-ring is made of a material with better heat resistance than the small diameter O-ring.