Undercarriage of construction machinery

Abstract

To effectively suppress intrusion of sediment into a shaft branch of a rotating body included in a lower structure.SOLUTION: A rotating body 20 is provided which is supported on support bodies 11 disposed at both sides of a lower structure 2 via a shaft branch 8. The shaft branch 8 has a sediment intrusion suppression structure 90a disposed in a part on an outer side from an oil seal part 80 in a gap 90 between the rotating body 20 and each of a pair of collars 40, 40. The sediment intrusion suppression structure 90a has a gap inlet part 91 with an outer peripheral side taper surface 24a formed thereon, and a gap innermost part 92 with a labyrinth structure formed thereon. A contraction part 93 with a small gap interval is disposed in an end portion inside the gap inlet part 91.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The disclosed technology relates to the undercarriage of a construction machine such as a hydraulic excavator, and in particular to technology for preventing foreign matter such as soil and sand from entering the bearing parts of a rotating body such as a guide roller provided on the undercarriage. [Background technology]

[0002] Many models of this type of construction machinery have a pair of crawlers (also called shoes) on both sides of the undercarriage. The crawler is stretched over a drive wheel and an idler wheel, guided by multiple rollers. The crawler rotates when the drive wheel is rotated by a hydraulic motor.

[0003] The idler wheels and rollers rotate as the crawler belt rotates. Lubricating oil is sealed inside the bearings of these rotating bodies by seals.

[0004] Construction machinery usually travels on uneven ground, so soil and sand adheres not only to the tracks but also to the rollers and other rotating parts. If soil and sand gets into the machinery through gaps in the bearings and reaches the seal material, its functionality will be reduced.

[0005] To address this problem, Patent Document 1 discloses a roller device that makes it difficult for soil and sand to enter the gap by aligning the positions of both ends of the gap entrance.

[0006] Furthermore, Patent Document 2 discloses a running device in which a labyrinth with a curved structure is provided in a gap, cloth-like members are placed in two places in the labyrinth, and grease is filled between these cloth-like members. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-147436 [Patent Document 2] Japanese Patent Application Publication No. 2018-128093 Summary of the Invention [Problem to be solved by the invention]

[0008] In the roller device of Patent Document 1, the distance from the entrance of the gap to the sealing material is short, so if soil or sand gets into the gap, it can easily reach the sealing material.

[0009] In contrast, the traveling device in Patent Document 2 has a long and complicated route from the opening of the gap to the sealing material, and the gap is sealed with grease midway through, so even if soil gets into the gap, there is almost no risk of the soil reaching the sealing material.

[0010] However, the complex structure and large number of parts require a large number of processing steps and high component costs. Furthermore, since the cloth material is prone to deterioration, fragments of the deteriorated cloth material may find their way into the gap and adversely affect the sealing material. Therefore, durability is poor.

[0011] In view of this, the technology disclosed here makes it possible to effectively prevent soil and sand from entering the support parts of rotating bodies provided on lower running bodies such as rollers, using a simple structure that is also highly durable. [Means for solving the problem]

[0012] The disclosed technology relates to a lower running body of a construction machine that travels by rotating tracks.

[0013] The undercarriage includes a pair of supports provided on both sides of the undercarriage in a vehicle width direction, and a rotor supported by the supports via a journal support with its outer periphery in contact with the inner surface of the crawler belt. The journal support includes a shaft extending in the vehicle width direction and inserted into a shaft hole of the rotor, a pair of collars attached to the shaft while being disposed on both sides of the rotor, oil seals provided within annular gaps between adjacent rotating wall surfaces of the rotor and the stationary wall surfaces of the collars, and sediment intrusion prevention structures provided in the gaps outside the oil seals.

[0014] The soil intrusion prevention structure extends in the vehicle width direction and has an outer end that is open, and has a gap inlet portion where an outer tapered surface that increases the gap spacing outward is formed on the rotating wall surface that constitutes the outer peripheral side of the end, and an inner gap portion where a labyrinth structure is formed.The inner end of the gap inlet portion is provided with a narrowed portion where the innermost end of the outer tapered surface is located closer to the opening than the innermost end of the fixed wall surface that constitutes the inner peripheral side of the end, thereby reducing the gap spacing.

[0015] The construction machine is equipped with a pair of tracks on its undercarriage, which rotate to move. Rotating bodies are supported on supports on both sides of the undercarriage to support and rotate the tracks. Between the rotating body and a collar that forms the bearing for the rotating body, there is an annular gap with an oil seal inside.

[0016] If soil and sand enters the gap and reaches the oil seal, it could impair the performance of the rotating body. Therefore, the lower running body is provided with a soil and sand intrusion prevention structure in the gap, outside the oil seal.

[0017] The soil intrusion prevention structure first has a gap inlet portion that extends in the vehicle width direction, has an open outer end, and has an outer tapered surface formed on a rotating wall surface that forms the outer periphery of that end. That is, due to this outer tapered surface, the gap inlet portion is formed so that the gap spacing widens outward. This makes it easy for soil to enter the gap inlet portion, but even if soil does enter, it can be easily removed.

[0018] Secondly, the gap has a deep inner portion where a labyrinth structure is formed. By providing a labyrinth structure, even if soil or sand gets into the gap, it is not possible for it to easily penetrate deep into the gap.

[0019] A narrowed portion with a small gap spacing is provided at the inner end of the gap entrance, so that the gap spacing at the gap entrance abruptly decreases at the narrowed portion.

[0020] By providing such a constricted portion deep inside the gap entrance where the gap spacing is large, soil that has entered the gap entrance tends to remain there. In other words, accumulation inside the gap entrance tends to form a mass of soil, making it difficult for the soil to enter small gaps. On the other hand, soil that has entered the gap entrance can be easily removed as described above, so the intrusion of soil into the deep part of the gap can be effectively suppressed.

[0021] The labyrinth structure effectively prevents sediment from entering the innermost part of the gap, and this, combined with the labyrinth structure, effectively delays sediment from reaching the oil seal located deep within the gap. This sediment intrusion prevention structure can be realized by simply modifying the shape of an existing product without the need for additional components, so there is no increase in the number of parts or processing man-hours, and the structure is simple and durable.

[0022] The fixed wall surface constituting the outer end of the gap inlet may further have an inner circumferential tapered surface that increases the gap spacing outward.

[0023] Unlike a rotating wall surface, a fixed wall surface does not rotate. Therefore, if sediment enters the portion located above the entrance of the annular gap, the sediment will accumulate on the fixed wall surface. In contrast, if an inner tapered surface is formed on the fixed wall surface, the portion of the fixed wall located above the entrance of the annular gap will also have a downward sloping surface toward the outside, which will facilitate the discharge of sediment that has entered and accumulated in that portion. The opening of the gap will also be larger, making it easier to remove sediment that has entered the entrance of the gap.

[0024] The inner tapered surface may be formed so that the gap distance becomes larger outward than the outer tapered surface.

[0025] As described above, the inner tapered surface does not rotate, unlike the outer tapered surface, so by forming the gaps so that they become larger outward, that is, by sloping them sharply downward outward, it is possible to facilitate the removal of soil and sand that has entered the gap entrance.

[0026] A radial gap extending perpendicular to the vehicle width direction may be provided in an introduction portion at the deepest part of the gap, and the throttle portion and the radial gap may be connected.

[0027] By connecting the narrowed portion and the radial gap perpendicular to it, it is possible to more effectively prevent soil and sand from entering the inner part of the gap.

[0028] The lower running body may also be provided with a slight bending portion at the connection portion between the constriction portion and the radial gap, the slight bending portion being composed of a minute radial gap that is connected to the constriction portion and extends parallel to the radial gap, and a minute axial gap that is connected to the minute radial gap and the radial gap and extends in the vehicle width direction.

[0029] The minute bends are equivalent to small labyrinth structures. By providing such minute bends connected to the inner part of the constricted section, it becomes difficult for soil and sand to pass over the minute bends. Therefore, soil and sand can be more effectively prevented from entering the inner part of the gap.

[0030] The minute radial gap may extend radially outward from the throttle portion in a state facing and parallel to the radial gap.

[0031] This increases the radial gap, making it possible to more effectively prevent soil and sand from entering the inner part of the gap. [Effects of the Invention]

[0032] The disclosed technology effectively prevents soil and sand from entering the shaft support portion of a rotating body provided on a lower running body such as a roller, despite its simple structure. Therefore, a durable lower running body can be realized at low cost. [Brief explanation of the drawings]

[0033] [Figure 1] FIG. 2 is a schematic view of the hydraulic excavator as seen from the left side. [Figure 2] FIG. 4 is a schematic view of the lower roller as seen from diagonally below. [Figure 3] 3 is a schematic cross-sectional view taken along the arrow line Y in FIG. 2. [Figure 4] FIG. 2 is a schematic cross-sectional view showing the structure of a main part of a lower roller. [Figure 5] FIG. 1 is an explanatory diagram of an application example 1 of a structure for preventing soil and sand intrusion. [Figure 6] FIG. 10 is an explanatory diagram of an application example 2 of the structure for preventing soil and sand intrusion. [Figure 7] FIG. 10 is an explanatory diagram of an application example 3 of the sediment intrusion prevention structure. [Figure 8] FIG. 10 is an explanatory diagram of an example of application to an idler wheel. DETAILED DESCRIPTION OF THE INVENTION

[0034] The disclosed technology will be described below based on embodiments thereof, but the following description is merely exemplary in nature.

[0035] <Construction machinery> Fig. 1 shows a hydraulic excavator 1 as an example of a construction machine suitable for application of the disclosed technology. The hydraulic excavator 1 is generally composed of a lower traveling body 2 and an upper rotating body 3 mounted on the lower traveling body so as to be able to rotate freely. Note that the front-rear, left-right, and up-down directions used in the description are based on the state shown in Fig. 1 in which the hydraulic excavator 1 is placed on flat ground.

[0036] An attachment 4 that performs lifting and excavation work and a cab 5 in which an operator sits and operates the attachment 4 and tracks 17 (described below) are installed side by side on the left and right sides at the front of the upper rotating body 3. A machinery room 6 that houses an engine, hydraulic pump, etc. is installed at the rear of the upper rotating body 3. A heavy counterweight 7 is also installed at the rear of the upper rotating body 3 to ensure fore-and-aft balance with the attachment 4 that performs work. Although not shown, a fuel tank, hydraulic oil tank, etc. are installed on the right side of the upper rotating body 3.

[0037] The lower traveling body 2 has a pair of crawler units 10, 10 on both sides in the left-right direction (vehicle width direction). Each crawler unit 10 has a crawler frame 11 (support) extending in the front-to-rear direction, a drive wheel 12 arranged at one end (the rear end in FIG. 1) of the crawler frame 11, and an idler wheel 13 arranged at the other end. The drive wheel 12 is attached to a traveling device 14 that generates rotational force using a hydraulic motor.

[0038] Each crawler unit 10 also has a plurality of guide rollers arranged between the drive wheels 12 and the idler wheels 13. Specifically, a plurality of upper rollers 15 are installed on the upper side of the crawler frame 11 at intervals in the front-to-rear direction. A plurality of lower rollers 16 are installed on the lower side of the crawler frame 11 at intervals in the front-to-rear direction.

[0039] Each of these drive wheels 12, idler wheels 13, lower rollers 16, and upper rollers 15 is rotatably supported by the crawler frame 11 via axle supports 8, which will be described later. A crawler belt 17 is stretched around each of these drive wheels 12, idler wheels 13, lower rollers 16, and upper rollers 15, and the outer peripheries of each of the drive wheels 12, idler wheels 13, lower rollers 16, and upper rollers 15 are in contact with the inner surface of the crawler belt 17.

[0040] The drive wheels 12 are provided with gear structures (so-called sprockets) that mesh with the crawler belts 17. Therefore, when the travelling device 14 drives the drive wheels 12, the crawler belts 17 rotate, and accordingly the idler wheels 13 also rotate. This allows the hydraulic excavator 1 to travel. At this time, the upper rollers 15 and lower rollers 16 support the crawler belts 17 and smoothly guide its rotation.

[0041] The hydraulic excavator 1 is usually used to operate on uneven ground such as at a construction site, and as a result, soil and sand adhere to the crawler unit 10. In response to this, a gap exists at the boundary between the rotating portion and the fixed portion of the support shaft 8 that supports the drive wheels 12, the idler wheels 13, the lower rollers 16, and the upper rollers 15. If soil and sand enters this gap (gap 90, described below) and reaches the depths of the support shaft 8, the function of the support shaft 8 is reduced. As a result, the smooth rotation of the drive wheels 12 and the like may be impaired or they may be damaged.

[0042] In contrast, this hydraulic excavator 1 has a simple structure that is also highly durable, and the lower traveling body 2 is designed to effectively prevent soil and sand from entering deep into gaps. The details of this will be explained using the lower roller 16 as an example.

[0043] <Lower roller 16> Fig. 2 shows a schematic diagram of the lower roller 16 as seen obliquely from below. Fig. 3 shows a schematic cross-sectional view taken along the arrow line Y in Fig. 2. The lower roller 16 is made up of a roller 20 (rotating body), a shaft 30, a pair of collars 40, 40, etc.

[0044] The crawler frame 11 has a pair of side plates 11a, 11a that extend in the front-rear direction while facing each other on the left and right, and a pair of edge plates 11b, 11b that extend along the lower edges of the side plates 11a, 11a. Each collar 40 is disposed below each of the edge plates 11b, 11b while facing each other on the left and right.

[0045] The collar 40 has a bearing portion 42 consisting of a thick cylindrical portion through which a bearing hole 41 passes, and a fastening portion 43 that is formed integrally with the bearing portion 42 and through which the bearing hole 41 passes. As shown in FIG. 2, a pair of boss portions 43a, 43a are formed to protrude from both sides of the bearing hole 41 of the fastening portion 43. Each boss portion 43a has a bolt hole 44 that passes through in a direction perpendicular to the bearing hole 41. The collar 40 is fixed to the edge plate 11b by inserting bolts 50 into these bolt holes 44, 44 and fastening them to the edge plate 11b.

[0046] Both ends of the shaft 30 are inserted into the bearing holes 41 of each collar 40. A pin hole 31 extending radially is formed at the end of the shaft 30. A pair of pin receiving holes 45, 45 extending parallel to the bolt hole 44 and overlapping both ends of the pin hole 31 are formed in the fastening portion 43. By press-fitting a pin 60 into these pin receiving holes 45, 45 and pin hole 31, the shaft 30 is fixed to the pair of collars 40, 40 in a state extending in the left-right direction.

[0047] The rollers 20 are multi-stage cylindrical members. A support portion 21 that receives the crawler belt 17 is formed in the middle of the rollers 20. Flange portions 22 that have a larger outer diameter than the support portions 21 are formed at both ends of the rollers 20. These flange portions 22 restrict the left and right movement of the crawler belt 17 so that the rotating crawler belt 17 does not come off the lower rollers 16.

[0048] The shaft 30 is inserted into the shaft hole 23 that passes through the center of the roller 20. An oil reservoir 23a with a large inner diameter is formed in the middle of the shaft hole 23. The oil reservoir 23a is filled with lubricating oil. On both sides of the oil reservoir 23a in the shaft hole 23, sliding contact portions 23b with an inner diameter slightly larger than that of the shaft 30 are formed. A cylindrical plain bearing 70 is disposed in the gap between the sliding contact portions 23b and the shaft 30. The roller 20 is rotatably supported on the shaft 30 via this plain bearing 70.

[0049] Fitting recesses 23c with an inner diameter larger than that of the sliding contact portions 23b are formed at both ends of the shaft hole 23. The bearing portions 42 of the collars 40 arranged on both sides of the roller 20 fit into these fitting recesses 23c, respectively. As a result, the roller 20 is arranged below the crawler frame 11 with its rotation axis J aligned in the left-right direction.

[0050] For convenience, in the following description of the gap 90, etc., the direction in which the rotation axis J extends (left and right or vehicle width direction) may be referred to as the axial direction, and the direction perpendicular to the rotation axis J may be referred to as the radial direction. When viewed relatively in the axial direction, the opening side of the gap 90 may be referred to as the axial outer side, and the side opposite the opening side of the gap 90 may be referred to as the axial inner side, and when viewed relatively in the radial direction, the outer circumferential side may be referred to as the radial outer side, and the inner circumferential side may be referred to as the radial inner side.

[0051] (gap 90) A gap 90 exists between the rotating roller 20 and the fixed collar 40. Specifically, as shown in Fig. 4, the wall surface (rotating wall surface 24) constituting the fitting recess 23c of the roller 20 and the wall surface (stationary wall surface 46) of the bearing portion 42 of each collar 40 fitted into the fitting recess 23c are close to each other, and an annular gap 90 exists between them.

[0052] The plain bearing 70 has a pair of flanges 70a, 70a that extend radially outward from both ends of the bearing 70. The portion of the annular gap 90 around the shaft 30 is filled by each of the flanges 70a, 70a entering between the roller 20 and the collar 40.

[0053] An oil seal portion 80 is provided at the end portion of the gap 90, which is closed by the flange portion 70a. The oil seal portion 80 is configured by accommodating a floating seal 82 in a seal accommodating chamber 81. The seal accommodating chamber 81 is formed by recessing the rotating wall surface 24 and the stationary wall surface 46, which configure the end portion of the gap 90, and widening the gap 90 in the axial direction.

[0054] The floating seal 82 is made up of two seal rings 82a, 82a and two elastic seal members (O-rings) 82b, 82b. The seal ring 82a is a metal annular member having an inclined seal receiving surface on its outer periphery.

[0055] The two seal rings 82a are accommodated in the seal accommodating chamber 81 with their seal receiving surfaces facing opposite directions and facing each other in the axial direction. The seal rings 82a are also accommodated in the seal accommodating chamber 81 in a state where they can rotate independently of each other.

[0056] An O-ring 82b is disposed between the seal receiving surface of one seal ring 82a and the rotating wall surface 24 of the roller 20 that constitutes the seal accommodating chamber 81, and the O-ring 82b is pressed against both the seal ring 82a and the roller 20. An O-ring 82b is disposed between the seal receiving surface of the other seal ring 82a and the stationary wall surface 46 of the collar 40 that constitutes the seal accommodating chamber 81, and the O-ring 82b is also pressed against both the seal ring 82a and the collar 40.

[0057] As a result, the interior of the seal accommodating chamber 81 is divided by the floating seal 82 into two spaces: an inner space 81a in which the seal ring 82a is located, and an outer space 81b in which the seal ring 82a is not located. The inner space 81a is connected to the oil reservoir 23a via the gap between the shaft 30 and the sliding contact portion 23b of the shaft hole 23 in which the plain bearing 70 is located, and the lubricating oil supplied from the oil reservoir 23a enters the inner space 81a.

[0058] On the other hand, the outer space 81b is connected to the outside via a gap 90. Therefore, if earth and sand gets into the gap 90, there is a risk that the earth and sand will enter the outer space 81b.

[0059] Therefore, in this hydraulic excavator 1, a structure for suppressing the intrusion of sediment (sediment intrusion suppression structure 90a) is provided in the gap 90, in a portion outside the oil seal portion 80. As shown in Fig. 3, the shaft support portion 8 is made up of the shaft 30, collar 40, oil seal portion 80, etc., including the gap 90 in which the sediment intrusion suppression structure 90a is provided.

[0060] <Sediment intrusion prevention structure 90a> The sediment intrusion prevention structure 90a has been devised to have a simple structure that is also highly durable and can effectively prevent sediment from entering the oil seal portion 80. As shown enlarged in Figure 4, the sediment intrusion prevention structure 90a is composed of a gap entrance portion 91 and a gap inner portion 92, which have different functions, and a throttle portion 93 that effectively performs both of these functions.

[0061] (Gap entrance 91) The gap entrance portion 91 is the outermost portion of the gap 90 and corresponds to the entrance of the gap 90. More specifically, the gap entrance portion 91 extends in the axial direction and is open at its outer end. A tapered surface (outer peripheral tapered surface 24a) that increases the gap spacing outward is formed on the rotating wall surface 24 of the roller 20 that forms the outer peripheral side of the outer end. The outer peripheral tapered surface 24a is composed of an inner curved surface portion 24ai and an outer curved surface portion 24ao that are curved in opposite radial directions.

[0062] The outer curved surface portion 24ao is configured as a curved surface (a curved surface having a horn-shaped cross section) whose inner diameter increases toward the outside, and its outer edge forms the edge of the opening of the shaft hole 23. The inner curved surface portion 24ai is configured as a curved surface (a curved surface having a cup-shaped cross section) whose inner diameter decreases toward the inside, and its outer edge smoothly connects to the outer curved surface portion 24ao.

[0063] Due to this outer peripheral tapered surface 24a, the gap entrance 91 is formed so that the gap spacing widens outward, making it easy for soil and sand to enter the gap entrance 91, but even if soil and sand do enter, it can be easily removed.

[0064] That is, when the gap entrance 91 into which the sediment has entered is positioned downward due to the rotation of the roller 20, the outer peripheral tapered surface 24a becomes a surface that slopes downward toward the outside. This facilitates the discharge of the entered sediment. Typically, a dirty lower running body 2 is cleaned using a high-pressure washer or the like. In this case, the large entrance of the gap 90 makes it easier for cleaning water to reach the gap 90, and the sediment that has entered the gap entrance 91 can be easily removed.

[0065] Furthermore, in this hydraulic excavator 1, the stationary wall surface 46 of the collar 40 that forms the inner peripheral side of the outer end of the gap entrance portion 91 also has a tapered surface (inner peripheral tapered surface 46a) that increases the gap spacing outward. The inner peripheral tapered surface 46a is composed of an inclined surface and a curved surface that has an arc-shaped cross section that continues axially outward from the inclined surface. The curved surface is formed by rounding the corners on the outer peripheral side of the bearing portion 42.

[0066] The curved surface of the inner circumferential tapered surface 46a is formed with a larger curvature than the outer curved surface portion 24ao. Therefore, the portion on the opening side of the gap entrance portion 91 is formed so that the gap spacing becomes larger outward at the inner circumferential tapered surface 46a than at the outer curved surface portion 24ao. Unlike the rotating wall surface 24, the fixed wall surface 46 is fixed to the crawler frame 11 and does not rotate. Therefore, if soil or sand enters the portion located above the annular gap entrance portion 91, the soil or sand will accumulate on the fixed wall surface 46.

[0067] On the other hand, if the immovable wall surface 46 is formed with an inner peripheral tapered surface 46a, the portion of the immovable wall surface 46 located above the annular gap entrance 91 also becomes an outwardly sloping surface, which can facilitate the discharge of sediment that has entered and accumulated in that portion. The opening of the gap 90 also becomes larger, making it even easier to remove sediment that has entered the gap entrance 91.

[0068] (Inner gap 92) The inner gap portion 92 is the inner portion of the gap 90, and is the portion between the gap entrance portion 91 and the oil seal portion 80. The inner gap portion 92 has a bent structure (labyrinth structure) with a small gap spacing so that even if soil or sand gets in, it cannot easily penetrate to the depths.

[0069] In the case of this hydraulic excavator 1, the labyrinth structure of the inner gap portion 92 is configured to be a relatively simple structure. Specifically, the inner gap portion 92 has three gaps extending in the radial direction (a first radial gap 92a, a second radial gap 92b, and a third radial gap 92c) as a result of the rotating wall surface 24 and the immovable wall surface 46 being fitted together with gaps 90 in between, and two gaps extending in the axial direction (a first axial gap 92d and a second axial gap 92e) alternately connected to these gaps 92a, 92b, and 92c.

[0070] That is, the first radial gap 92a constitutes the introduction portion of the inner gap portion 92, and its radially outer end portion is connected to the gap inlet portion 91. The radially inner end portion of the first radial gap 92a is connected to the axially inner end portion of the first axial gap 92d. The axially outer end portion of the first axial gap 92d is connected to the radially outer end portion of the second radial gap 92b.

[0071] The radially inner end of the second radial gap 92b is continuous with the axially outer end of the second axial gap 92e. The axially inner end of the second axial gap 92e is continuous with the radially outer end of the third radial gap 92c. The radially inner end of the third radial gap 92c is continuous with the oil seal portion 80.

[0072] By providing such a labyrinth structure, even if soil or sand penetrates into the inner gap portion 92, it is possible to prevent it from easily penetrating the inner gap portion 92. The more bends there are, the better the effect of preventing soil or sand from penetrating, but the more complex the structure becomes. This also makes processing more difficult, and the area required to provide the labyrinth structure increases both axially and radially. This may result in an increase in the size of the lower roller 16 and a decrease in its strength.

[0073] In contrast, in the case of this hydraulic excavator 1, the labyrinth structure is configured with a minimum number of bends, so the structure is simple and sufficient strength can be ensured even if the lower roller 16 is of a conventional size.

[0074] Furthermore, the second axial gap 92e is formed to be longer than the first axial gap 92d, and the first radial gap 92a is positioned axially outward of the third radial gap 92c. This allows the thickness of the base end portion of the flange portion 22 of the roller 20 (the thickness indicated by the arrow W in FIG. 4) to be increased, ensuring sufficient strength for the flange portion 22 to withstand the lateral load received from the crawler belt 17.

[0075] On the other hand, constructing a labyrinth structure with a minimum number of bends is disadvantageous from the perspective of preventing the intrusion of soil and sand. Therefore, in the case of this hydraulic excavator 1, a throttle portion 93 is provided at the boundary between the gap entrance portion 91 and the innermost gap portion 92. The throttle portion 93 effectively fulfills the functions of both the gap entrance portion 91 and the innermost gap portion 92, thereby enabling a simple structure that is also highly durable to effectively prevent the intrusion of soil and sand into the oil seal portion 80.

[0076] (Throttling section 93) The throttle portion 93 is provided at the inner end of the gap inlet portion 91, and as described above, is connected to the first radial gap 92a in the inner gap portion 92. The throttle portion 93 is made up of narrow gaps 90, and is configured so that the gap spacing of the gap inlet portion 91 suddenly becomes smaller at the throttle portion 93.

[0077] Specifically, the innermost end P2 (more specifically, the innermost end P2 of the inner curved surface portion 24ai) of the outer tapered surface 24a that forms the outer side of the end of the gap entrance portion 91 is positioned axially outward from the axially inner end (innermost end P1) of the fixed wall surface 46 that forms the inner side of the end of the gap entrance portion 91, thereby providing the constriction portion 93.

[0078] Structurally, the radial dimension can be more precisely dimensioned than the axial dimension, so by forming a throttling portion 93 at the gap inlet portion 91 extending in the axial direction, a throttling portion 93 with a small gap spacing can be formed with high precision.

[0079] By providing a constriction 93 that suddenly reduces the gap spacing deep inside the gap entrance 91 where the gap spacing is large, soil that has entered the gap entrance 91 is more likely to remain there. In other words, accumulation inside the gap entrance 91 makes it easier for clumps of soil to form, making it more difficult for the soil to enter small gaps. On the other hand, soil that has entered the gap entrance 91 can be easily removed as described above, so the intrusion of soil into the deep gap 92 can be effectively suppressed.

[0080] The intrusion of sediment into the inner gap portion 92 is made more difficult, and this, combined with the labyrinth structure, effectively delays the sediment from reaching the oil seal portion 80 located at the back of the inner gap portion 92. The sediment intrusion prevention structure 90a can be realized by simply changing the shapes of the roller 20 and collar 40, without assembling any new components, and therefore there is no increase in the number of parts or processing man-hours, and the structure is also excellent in durability.

[0081] <Application example 1> 5 shows Application Example 1 of the sediment intrusion prevention structure 90a. Except for the main parts of the sediment intrusion prevention structure 90a, the basic configuration of the hydraulic excavator 1 is the same. Therefore, the same members and structures as in the above-described embodiment are denoted by the same reference numerals, and their description will be omitted (the same applies to Application Example 2 below, etc.).

[0082] In the soil / sand intrusion prevention structure 90a of application example 1, in addition to the constriction portion 93, a minute bend portion 100 is provided at the connection portion between the constriction portion 93 and the first radial gap 92a in order to more effectively prevent soil / sand from invading into the innermost portion 92 of the gap.

[0083] The minute bend portion 100 corresponds to a small labyrinth structure, so to speak, and is constituted by a stepped gap 90 that is bent slightly into an L-shaped cross section. Specifically, the minute bend portion 100 is constituted by a short gap (minute radial gap 100a) that continues to the throttle portion 93 and extends slightly while facing and parallel to the first radial gap 92a, and a short gap (minute axial gap 100b) that continues to both the minute radial gap 100a and the first radial gap 92a and extends slightly in the axial direction.

[0084] The minute radial gap 100a extends radially inward from the constricted portion 93, and the minute axial gap 100b extends axially inward from the minute radial gap 100a. By providing such a minute bend portion 100 connected to the inner side of the constricted portion 93, it becomes difficult for soil and sand to pass over the minute bend portion 100. Therefore, it is possible to more effectively prevent soil and sand from entering the inner gap portion 92.

[0085] <Application example 2> 6 shows an application example 2 of the sediment intrusion suppression structure 90a. In this sediment intrusion suppression structure 90a, the shape of the minute bend portion 100 is different from that in the application example 1.

[0086] That is, while the minute radial gap 100a in Application Example 1 extends radially inward from the constricted portion 93, the minute radial gap 100a in Application Example 2 extends radially outward from the constricted portion 93. As a result, the first radial gap 92a is longer than in Application Example 1, and the intrusion of soil and sand into the inner gap portion 92 can be more effectively prevented.

[0087] <Application example 3> 7 shows an application example 3 of the sediment intrusion prevention structure 90a. In this sediment intrusion prevention structure 90a, the labyrinth structure of the innermost gap portion 92 differs from that of the above-described embodiment.

[0088] That is, a more advanced labyrinth structure with a greater number of bends is formed in the innermost gap portion 92 of this sediment intrusion prevention structure 90a by increasing the number of folds in the gap 90. Specifically, the labyrinth structure is made up of five radial gaps 105 and four axial gaps 106.

[0089] Furthermore, the axial gap 106 is configured to become longer as it goes deeper from the inlet side. Therefore, because the overall length of the inner gap portion 92 is extended and the number of bends is increased, even if soil or sand enters the inner gap portion 92, it is possible to effectively prevent the soil or sand from reaching the oil seal portion 80.

[0090] <Other embodiments> In the above-described embodiment, the disclosed technology is applied to the lower roller 16. In this embodiment, an example of application to the idler wheel 13 will be described.

[0091] Figure 8 shows an idler 13 (so-called idler). The basic configuration of the idler 13 is the same as that of the lower roller 16. That is, the idler 13 has a wheel 110 (rotating body) around which the crawler belt 17 is wound, instead of the roller 20. Apart from this, the members constituting the journal support 8, such as the shaft 30 and collar 40, are virtually the same between the lower roller 16 and the idler 13. Therefore, the same members as those in the above-described embodiment are denoted by the same reference numerals in Figure 8, and their description will be omitted.

[0092] Axial holes 23 that pass through the center of hub 111 are opened at both ends of hub 111, and fitting recesses 23c are formed in these holes to fit bearing portions 42 of collar 40. An oil seal portion 80 is provided deep in a gap 90 that exists between the rotating wheel 110 and the fixed collar 40, and the above-mentioned soil intrusion prevention structure 90a is provided in the gap 90 located closer to the entrance of the oil seal portion 80.

[0093] Therefore, this idler wheel 13 has a simple structure and can effectively prevent soil and sand from entering the journal support portion 8 of the wheel 110. The disclosed technology can also be applied to the drive wheel 12 and the upper roller 15. Therefore, if applied to these, the durability of the lower traveling body 2 can be further improved.

[0094] The disclosed technology is not limited to the above-described embodiment, and includes various other configurations. For example, the construction machine to which the disclosed technology can be applied is not limited to a hydraulic excavator. The disclosed technology can be applied to any construction machine equipped with a lower traveling body that travels by rotating crawlers.

[0095] The above-described embodiments and application examples may be combined as appropriate. The configuration of the rollers and collars may also be changed as appropriate according to the required specifications. While the object of intrusion prevention is primarily soil and sand, it goes without saying that any foreign object that infiltrates into gaps, not just soil and sand, may be the object of prevention. [Explanation of symbols]

[0096] 1. Hydraulic excavator (construction machinery) 2 Undercarriage 3 Upper rotating body 8 axis branches 10 Crawler Unit 11 Crawler frame (support) 12 drive wheels 13 Idler 14 Running gear 15 Upper roller 16 Lower roller 17 Tracks 20. Laura 23 shaft hole 23c Fitting recess 24 Rotating wall 24a Outer tapered surface 30 shaft 40 colors 46 Immovable Wall 46a Inner tapered surface 70 Plain bearing 80 Oil seal part 82 Floating Seal 90 Gap 90a Sediment intrusion prevention structure 91 Gap entrance 92 Deep inside the gap 93 Constriction section

Claims

1. A lower running body of a construction machine that runs by rotating a crawler, A pair of supports provided on both sides of the lower traveling body in the vehicle width direction; a rotating body supported by the support body via a journal portion with an outer circumferential portion in contact with the inner surface of the crawler belt; Equipped with The pivot support portion is a shaft extending in the vehicle width direction and inserted into a shaft hole of the rotating body; a pair of collars attached to the shaft and disposed on both sides of the rotating body; an oil seal portion provided inside an annular gap between a rotating wall surface of the rotor and each of the stationary wall surfaces of the collars, the rotating wall surface being close to each other; a sediment intrusion prevention structure provided in a portion of the gap outside the oil seal portion; and The soil intrusion prevention structure is a gap inlet portion that extends in the vehicle width direction, has an outer end that opens, and has an outer circumferential tapered surface formed on the rotating wall surface that forms the outer circumferential side of the end, the outer circumferential tapered surface increasing the gap interval toward the outside; a deep portion of the gap in which a labyrinth structure is formed; and a throttle portion having a small gap interval is provided at an inner end of the gap inlet portion, with the innermost end of the outer tapered surface being located closer to the opening than the innermost end of the fixed wall surface that constitutes the inner circumferential side of the end, the outer peripheral tapered surface has an inner curved surface portion and an outer curved surface portion that are curved in opposite radial directions, A lower running body in which the outer curved surface portion is composed of a curved surface whose inner diameter increases toward the outside, and the inner curved surface portion is composed of a curved surface whose inner diameter decreases toward the inside, and the outer edge of the inner curved surface portion is smoothly connected to the outer curved surface portion.

2. The undercarriage according to claim 1, A lower running body, wherein the fixed wall surface constituting the outer end of the gap entrance portion is further formed with an inner circumferential tapered surface that increases the gap spacing outward.

3. The lower traveling body according to claim 2, The lower running body is formed so that the gap distance becomes larger outward on the inner tapered surface than on the outer tapered surface.

4. The undercarriage according to any one of claims 1 to 3, A radial gap extending perpendicular to the vehicle width direction is provided in an introduction portion deep within the gap, and the constricted portion and the radial gap are connected to the lower running body.

5. The undercarriage according to claim 4, A lower running body is provided with a slight bending portion at the connection portion between the constricted portion and the radial gap, the slight bending portion being composed of a slight radial gap that is connected to the constricted portion and extends parallel to the radial gap, and a slight axial gap that is connected to the slight radial gap and the radial gap and extends in the vehicle width direction.

6. The undercarriage according to claim 5, a lower running body, the minute radial gap extending radially outward from the throttle portion in a state facing and parallel to the radial gap;

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