Lower frame structure of construction machine

Abstract

To provide a lower frame structure of a construction machine capable of avoiding interference between a motor case and a crawler belt, and ensuring a height of the motor case.SOLUTION: The present invention relates to a lower frame structure of a construction machine that has a travel body 30 provided with a crawler 32 including an activation wheel 34 attached to a front end of a side frame 33 together with a travel motor 38, a motor case 39 accommodating the travel motor 38, and a crawler belt 37 surrounding the side frame 33, the activation wheel 34, and a ground roller 36. A crawler shoe 37a included in the crawler belt 37 includes an engagement part 37c that projects to the inside of a main unit 37b and is engaged with the activation wheel 34. A top surface 39d of the motor case 39 has a slope part 39g which exhibits such a gradient that the slope part rises from a position below the engagement part 37c of the crawler shoe 37a located above toward the inside in a horizontal direction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to the structure of a lower frame that constitutes a traveling body in a construction machine equipped with a crawler-type traveling body.

Background Art

[0002] FIG. 8 shows a crawler carrier as an example of a construction machine. A frame 2 that constitutes the vehicle body of the crawler carrier 1 is rotatably attached via a slewing ring 4 on a traveling body 3, and a cab 5 is installed at the front part on the frame 2. A loading platform 6 is attached to the rear of the cab 5 so as to be able to rise and fall.

[0003] As shown in FIG. 9, the traveling body 3 is configured to include a pair of crawlers 8 on the left and right of a lower frame 7. Each crawler 8 includes a drive wheel 10 at one end side of a side frame 9 that extends in the traveling direction and a trailing wheel 11 at the other end side. A plurality of ground rollers 12 are swingably attached to the lower part of the side frame 9, and an upper roller 16 is attached to the upper part. An endless crawler belt 13 is provided so as to surround these. When the drive wheel 10 rotates by the operation of a traveling motor 14, the rotation is transmitted to the trailing wheel 11 and the ground rollers 12 via the crawler belt 13, and the ground rollers 12 rotate together with the crawler belt 13 with respect to the ground, so that the entire crawler 8 moves back and forth.

[0004] A drive wheel 10 is attached together with the traveling motor 14 to one end side of a side frame 9 that is provided on the left and right of the lower frame 7 and forms the skeleton of the crawler 8.

[0005] Motor cases 15 for housing the traveling motor 14 and supporting it together with the drive wheel 10 are formed at the installation positions of the traveling motors 14 on the left and right of the lower frame 7. As shown in FIGS. 9 and 10, the motor case 15 includes a mounting surface portion 15a that supports the drive wheel 10 which is a sprocket, and an outer peripheral surface portion 15b that extends inward in the left-right direction of the vehicle from the mounting surface portion 15a.

[0006] The attachment surface portion 15a forms a surface along the traveling direction and the vertical direction of the traveling body 3 at one end side in the left - right direction (one end side regarding the front - rear direction) of the lower frame 7. In the central portion, a circular attachment hole 15c for attaching the traveling motor 14 is opened so as to penetrate the attachment surface portion 15a in the left - right direction. The traveling motor 14 is attached to the motor case 15 such that the main body portion is located inside in the left - right direction with respect to the attachment surface portion 15a, and the portion provided with the drive wheel 10 is located outside in the left - right direction with respect to the attachment surface portion 15a. The attachment hole 15c provided in the attachment surface portion 15a is in a form that the portion of the traveling motor 14 provided with the drive wheel 10 penetrates in the left - right direction, and the drive wheel 10 is attached so as to be located slightly outside in the left - right direction with respect to the attachment surface portion 15a.

[0007] The outer peripheral surface portion 15b is provided so as to surround the main body portion of the traveling motor 14 that is located inside with respect to the attachment surface portion 15a. The outer peripheral surface portion 15b has a substantially cylindrical shape so as to surround the main body portion of the traveling motor 14 in the circumferential direction and extends inward in the left - right direction from the attachment surface portion 15a. The drive wheel 10 supported on the outer side in the left - right direction of the attachment surface portion 15a projects radially outward from there to the outer peripheral surface portion 15b, and the crawler belt 13 is wound around its outer periphery.

[0008] As prior art documents disclosing techniques related to the frame structure in this type of construction machine, for example, there are the following Patent Document 1 etc.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0010] Here, in the traveling body 3, it is necessary to avoid interference between the motor case 15, which is a member fixed to the lower frame 7 side, and the crawler 13 that operates relative thereto. As shown in FIG. 10, the crawler shoe 13a, which is a constituent member of the crawler 13 wound around the drive wheel 10, which is a sprocket, is positioned so as to project laterally from the outer periphery of the drive wheel 10 at the position where it meshes with the drive wheel 10. The motor case 15 that houses the traveling motor 14 connected to the drive wheel 10 needs to be provided inside at least the rotating range of the crawler 13 in order to avoid contact with the crawler shoe 13a thus attached. Since the drive wheel 10 and the traveling motor 14 are positioned inside the crawler 13 to rotate the crawler 13, at least a part of the motor case 15 that houses them will inevitably be positioned inside the rotating range of the crawler 13. And in such a positional relationship, if an attempt is made to avoid contact between the motor case 15 and the crawler 13, the vertical dimension of the motor case 15 (shown as height H1 in FIG. 10) will be smaller than the rotating range of the crawler 13. That is, the height H1 of the motor case 15 is smaller than the distance D between the inner surfaces of the crawler 13.

[0011] On the one hand, the motor case 15 is a part in the lower frame 7 that is likely to receive external forces during travel. For example, when the traveling body 3 is traveling toward one end side equipped with the drive wheel 10, if there is a foreign object such as a stone in front in the traveling direction, the motor case 15 will collide with the foreign object sandwiching the crawler 13. An external force in a direction that tries to push up the motor case 15 or push it backward with respect to the traveling direction is applied to the motor case 15. Of course, the lower frame 7 and the motor case 15 are designed with their strength calculated in anticipation of such a situation. However, in that design, the dimensional limitations of the motor case 15 in avoiding contact with the crawler 13 as described above work disadvantageously. To maintain rigidity and strength against the external force applied to the motor case 15, it is effective to increase the vertical dimension (height H1 in FIG. 10) of the motor case 15. However, if one tries to avoid contact with the crawler 13, there is naturally a limit to the size of the height H1. In view of this, in order to maintain strength, it is necessary to adopt a method such as increasing the thickness of the steel material constituting the motor case 15, or designing the crawler 8 itself to be higher to increase the distance between the upper and lower crawlers 13 and then increasing the height H1 of the motor case 15. This has been a limiting factor in the weight reduction of the vehicle body.

[0012] In view of such circumstances, the present invention aims to provide a lower frame structure of a construction machine that can secure the height of the motor case while avoiding interference between the motor case and the crawler.

Means for Solving the Problem

[0013] The present invention relates to a lower frame structure of a construction machine provided with a crawler on a traveling body, the crawler being configured to include side frames attached to the left and right of a lower frame, drive wheels attached together with a traveling motor to the front end portions of the side frames, a motor case for housing the traveling motor, ground rollers attached to the lower portions of the side frames, and a crawler provided so as to surround the side frames, the drive wheels, and the ground rollers. The crawler shoes constituting the crawler are provided with engaging portions that project inside the main bodies and engage with the drive wheels. The upper surface of the motor case is provided with a sloped surface that forms an upward gradient as it goes inward in the left-right direction from a position corresponding to below the engaging portion of the crawler shoe located above. This is a lower frame structure of a construction machine characterized by this.

[0014] In the lower frame structure of the construction machine of the present invention, the upper surface of the motor case may further be provided with a parallel surface portion that extends inward in the left-right direction with respect to the sloped surface and forms a surface parallel to the main body of the crawler shoe located above.

[0015] In the lower frame structure of the construction machine of the present invention, the sloped surface portion and the parallel surface portion may be integrally formed as continuous plate materials.

[0016] In the lower frame structure of the construction machine of the present invention, a mounting bracket connected to the lower portion of the side frame may be provided, and the ground roller may be rotatably attached to a swing bracket that is swingably supported via a swing pin below the mounting bracket.

Advantages of the Invention

[0017] According to the lower frame structure of the construction machine of the present invention, it is possible to achieve an excellent effect of securing the height of the motor case while avoiding interference between the motor case and the crawler.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Embodiments for Carrying out the Invention

[0019] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0020] FIGS. 1 to 6 show an example of the lower frame of a construction machine according to the implementation of the present invention, a crawler-type traveling body to which it is applied, and the form of a construction machine. In this embodiment, a swing-type crawler carrier is assumed as the construction machine 100. In the crawler carrier 100, as shown in FIG. 6, a frame 2 is rotatably attached to the traveling body 30 via a slewing ring 4, a cab 5 is installed at the front part on the frame 2, and a loading platform 6 is attached to the rear of the cab 5 so as to be able to rise and fall.

[0021] The traveling body 30 is provided with a pair of crawlers 32 on the left and right. Each crawler 32 is provided with a drive wheel 34 at one end of a side frame 33 extending in the traveling direction, and a trailing wheel 35 at the other end. A plurality of ground rollers 36 are swingably attached to the lower part of the side frame 33, and an upper roller 40 is attached to the upper part. Hereinafter, for convenience of explanation, in the traveling direction of the crawler 32, the side where the drive wheel 34 is provided will be defined as "front", and the side where the trailing wheel 35 is provided will be defined as "rear" (especially in the case of the swing-type construction machine 100, there are cases where it travels with the trailing wheel 35 side as the front of the traveling direction, but in this specification, it will be defined as above regardless of the actual traveling direction).

[0022] Around the side frame 33 and the drive wheel 34, trailing wheel 35, ground roller 36 and upper roller 40 attached thereto, a crawler 37 is annularly provided so as to surround them all. When the drive wheel 34 rotates due to the operation of the traveling motor 38 connected to the drive wheel 34, the rotation is transmitted to the trailing wheel 35 and the ground roller 36 via the crawler 37, and the ground roller 36 rotates together with the crawler 37 with respect to the ground, so that the entire crawler 32 moves back and forth.

[0023] The form of the traveling body 30 and the lower frame 31 constituting the same is as shown in FIGS. 1 and 2. The lower frame 31 is formed in a substantially X shape in plan view as a whole, and a slewing ring 4 is provided at the upper part of the center. Side frames 33 forming the skeletons of the crawlers 32 are connected to the left and right of the lower frame 31, respectively. A motor case 39 is provided at a position corresponding to the front part of each side frame 33 on the lower frame 31, and the drive wheel 34 is attached there together with the traveling motor 38.

[0024] The motor case 39 is a part of the lower frame 31 that houses the traveling motor 38 and supports it together with the drive wheel 34. The motor case 39 is configured to include a mounting surface portion 39a that supports the drive wheel 34, which is a sprocket, and an outer peripheral surface portion 39b that extends inward in the left-right direction from the mounting surface portion 39a.

[0025] The mounting surface portion 39a is a plate-like member that forms a surface along the traveling direction and in the vertical direction of the traveling body 30 on the left and right front end sides of the lower frame 31. A circular mounting hole 39c for mounting the traveling motor 38 is opened at the center of the mounting surface portion 39a so as to penetrate the mounting surface portion 39a from left to right. The traveling motor 38 is attached to the motor case 39 such that the main body portion is located inside with respect to the mounting surface portion 39a in the left-right direction, and the portion where the drive wheel 34 is attached is located outside with respect to the mounting surface portion 39a in the left-right direction. The mounting hole 39c provided in the mounting surface portion 39a is in a shape where the portion of the traveling motor 38 having the drive wheel 34 penetrates from left to right, and the drive wheel 34 is attached in a direction along the surface formed by the mounting surface portion 39a, slightly outside with respect to the mounting surface portion 39a in the left-right direction. The drive wheel 34 is supported so as to project radially outward from the vicinity of the mounting hole 39c with respect to the motor case 39, and a crawler belt 37 is wound around the outer periphery of the drive wheel 34.

[0026] The outer peripheral surface portion 39b is provided so as to surround the main body portion of the traveling motor 38 that is located inside with respect to the mounting surface portion 39a. The outer peripheral surface portion 39b forms a substantially cylindrical outer wall so as to surround the main body portion of the traveling motor 38 in the circumferential direction, and extends inward in the left-right direction from the mounting surface portion 39a.

[0027] The above configuration is common to the conventional examples shown in FIGS. 8 to 10. However, in the case of the crawler carrier 100 of the present embodiment, the shape of the motor case 39 is different from that of the motor case 15 in the conventional example. Specifically, it has a feature in the shape of the upper surface 39d of the outer peripheral surface portion 39b.

[0028] The shape of the outer peripheral surface portion 39b of this motor case 39 will be described in detail. The motor case 39 is provided in the lower frame 31 in a form that protrudes forward from the position at the front end of the side frame 33. At the front end portion of the side frame 33, there is provided a front end surface portion 33a that forms a surface along the vertical direction and along a direction orthogonal to the traveling direction. The outer peripheral surface portion 39b of the motor case 39 protrudes so as to form a C shape in a side view from the front end surface portion 33a. When looking at the lower frame 31 from the side, both ends of the C-shaped curve formed by the outer peripheral surface portion 39b of the motor case 39 are in contact with the front end surface portion 33a of the side frame 33, and the entire curve protrudes forward therefrom. In other words, the members forming the upper surface 39d and the lower surface 39e of the outer peripheral surface portion 39b both protrude forward with the front end surface portion 33a as the base, and merge together at the tip side (the cylindrical surface-like portion forming the intermediate portion in the C-shaped curve) (hereinafter, among the outer peripheral surface portion 39b, the portion that forms a cylindrical surface at this front end and surrounds the traveling motor 38 is referred to as the surrounding portion 39f). A support surface portion 39a is located in the region surrounded by the C-shaped curve, and a mounting hole 39c opens at the center thereof so as to have the same axis as the surrounding portion 39f that forms a cylindrical surface. Incidentally, the upper surface 39d and the lower surface 39e of the outer peripheral surface portion 39b are, that is, the upper surface and the lower surface of the motor case 39 itself.

[0029] Most of the outer peripheral surface portion 39b is located inside with respect to the support surface portion 39a in the left-right direction as described above, but a part on the base side extends outside with respect to the support surface portion 39a. That is, the members forming the upper surface 39d and the lower surface 39e of the outer peripheral surface portion 39b are located straddling the support surface portion 39a left and right at the base end connected to the front end surface portion 33a, but as they extend forward from there, the width becomes narrower in a form in which the outer member in the left-right direction is cut out, and in the vicinity of the position where the mounting hole 39c is provided in the support surface portion 39a, it extends only almost inside with respect to the support surface portion 39a in the left-right direction. The same is true for the surrounding portion 39f located on the more tip side.

[0030] The reason why the width of the outer peripheral surface portion 39b becomes narrower at the tip side in this way is that the outer peripheral surface portion 39b does not interfere with the starting wheel 34 supported on the foremost end side. The reason why the widths of the upper surface 39d and the lower surface 39e are set wider than that at the base side is to ensure the rigidity of the connection portion between the motor case 39 and the front end surface portion 33a.

[0031] And in the case of this embodiment, it is characterized in that a gradient is provided in the region on the base side of the upper surface 39d so as to become higher as it goes from the outside to the inside in the left - right direction.

[0032] Among the upper surface 39d, the portion on the base side where such a gradient is provided is referred to as the inclined surface portion 39g. The inclined surface portion 39g is a substantially triangular region extending forward from the front end surface portion 33a of the side frame 33 in FIG. 1. Among the upper surface 39d, the portion extending forward and inward in the left - right direction on the tip side of the inclined surface portion 39g (the triangular region sandwiched front - and - rear by the inclined surface portion 39g and the surrounding portion 39f in FIG. 1; this region is defined as the parallel surface portion 39h) does not have the gradient as described above.

[0033] As shown in FIG. 1, the substantially triangular inclined surface portion 39g extends forward with the portion of the upper surface 39d in contact with the front end surface portion 33a of the side frame 33 as the base 39i. The base 39i extends to both the left and right sides with respect to the support surface portion 39a at the front end surface portion 33a. The remaining two hypotenuses of the triangle formed by the inclined surface portion 39g are the outer edge (referred to as the first hypotenuse 39j) in the left - right direction of the inclined surface portion 39g itself and the boundary with the parallel surface portion 39h located inside (referred to as the second hypotenuse 39k). The vertex of the inclined surface portion 39g, which is the intersection of the first hypotenuse 39j and the second hypotenuse 39k, is located directly above the support surface portion 39a.

[0034] The first hypotenuse 39j extends obliquely forward from the vertex located outside in the left - right direction of the base 39i while forming a convex curve toward the inside of the inclined surface portion 39g, toward the vertex that is the intersection point with the second hypotenuse 39k. That is, the inclined surface portion 39g has a shape that is curved at the first hypotenuse 39j. It is a shape to avoid interference with the drive wheel 34 provided in the front. The second hypotenuse 39k extends linearly and obliquely forward from the vertex located inside in the left - right direction of the base 39i, toward the vertex that is the intersection point with the first hypotenuse 39j.

[0035] The parallel surface portion 39h extends forward from the second hypotenuse 39k and forms a surface parallel to the main body 37b of the crawler shoe 37a located above it (see FIGS. 3 - 5). In the case of this embodiment, the surface formed by the parallel surface portion 39h is nearly horizontal, but has a slightly downward gradient toward the front. This parallel surface portion 39h is located in front of the inclined surface portion 39g and is located inside in the left - right direction. The ratio it occupies in the left - right direction of the upper surface 39d is close to zero near the front end surface portion 33a (the rear end portion of the upper surface 39d) and becomes larger toward the front. At the front end of the upper surface 39d, the parallel surface portion 39h occupies the entire left - right direction, and in front of it is followed by the surrounding portion 39f.

[0036] Here, the second hypotenuse 39k as the boundary with the parallel surface portion 39h has been described to explain the shape of the inclined surface portion 39g, but this is a virtual boundary line, and there is not necessarily a physical boundary between the parallel surface portion 39h and the inclined surface portion 39g (although the second hypotenuse 39k is shown as a solid line in FIG. 1, this indicates the ridge line that appears on the surface of the member constituting the portion from the inclined surface portion 39g to the parallel surface portion 39h, and there is no boundary between the two parts). That is, the upper surface 39d of the outer peripheral surface portion 39b can be formed by bending a single plate material, with a part of it being the inclined surface portion 39g and another part being the parallel surface portion h. By integrally configuring the inclined surface portion 39g and the parallel surface portion h as a continuous plate material in this way, the strength of the upper surface 39d in the motor case 39 can be suitably maintained.

[0037] Regarding the shape of the upper surface 39d having the inclined surface 39g and the parallel surface 39h, it will be further described with reference to FIGS. 3 to 5. For convenience of explanation, among FIGS. 3 to 5 showing the cross-section of the motor case, only FIG. 4 shows both the starting wheel 34 and the crawler shoe 37a.

[0038] As described above, the inclined surface 39g having a substantially triangular shape has a gradient that rises from the outside to the inside in the left-right direction, and a slightly rising gradient from the front to the front in the front-rear direction. On the other hand, the parallel surface 39h extending forward from the inclined surface 39g is parallel to the rotation axis of the starting wheel 34 in the left-right direction (therefore, parallel to the ground and parallel to the crawler shoe 37a extending in the left-right direction), and has a slightly downward gradient from the front to the front in the front-rear direction. Therefore, the second hypotenuse 39k forming the boundary between the inclined surface 39g and the parallel surface 39h forms a ridge line on the upper surface 39d of the outer peripheral surface 39b. Further, the inclined surface 39g has a slightly upwardly convex shape from the base 39i to the second hypotenuse 39k. That is, although not shown, the cross-section of the vertical plane parallel to the first inclined surface 39j of the inclined surface 39g bulges slightly upward.

[0039] In the portion near the front end surface 33a, the upper surface 39d has an upward gradient from the outside to the inside in the left-right direction as shown in the front cross-section of FIG. 3. This is, that is, the gradient of the inclined surface 39g. The front cross-section slightly ahead of that has, as shown in FIG. 4, a gradient that rises from the outside to the inside in the portion (inclined surface 39g) outside the second hypotenuse 39k in the left-right direction, and is parallel to the ground in the portion (parallel surface 39h) inside the second hypotenuse 39k in the left-right direction. The front cross-section further ahead has, as shown in FIG. 5, a direction parallel to the ground over the entire left-right direction (parallel surface 39h). Since the lower surface 39e has a downward gradient from the front to the front, the cross-section of the lower surface 39e in the front cross-sections of FIGS. 3 to 5 appears on the lower side in the order of FIGS. 3, 4, and 5.

[0040] The above-described shape on the upper surface 39d of the outer peripheral surface 39b is a configuration for ensuring the height of the entire motor case 39 (the dimension H2 in the height direction; see FIG. 4) while avoiding interference with the crawler shoe 37a. To maintain high strength and rigidity of the motor case 39, it is effective to set the upper surface 39d at as high a position as possible and make the height H2 large. On the other hand, since the crawler shoe 37a is located above the motor case 39, the upper surface 39d cannot be arranged so high as to contact it. Here, as shown in FIG. 4, the main body 37b of the crawler shoe 37a that forms the ground contact surface extends parallel to the ground along the left-right direction. However, the portion (referred to as the meshing portion 37c) that meshes with the drive wheel 34 and the ground contact roller 36 inside the crawler belt 37 (see FIG. 6) protrudes from the intermediate portion in the left-right direction of the main body 37b toward the drive wheel 34 and the ground contact roller 36 inside the crawler belt 37. That is, the crawler shoe 37a located near the upper part of the drive wheel 34 is in a positional relationship where it approaches the upper surface 39d of the motor case 39 below at the intermediate portion (meshing portion 37c) in the left-right direction and moves away upward from the upper surface 39d of the motor case 39 at other portions. Therefore, in this embodiment, as described above, a slope is provided in the form of the inclined surface 39g on the upper surface 39d. The upper surface 39d is lowered at a position corresponding to below the meshing portion 37c protruding from the crawler shoe 37a located above, and from there, in the inner side in the left-right direction, the upper surface 39d is gradually increased with a slope that rises more inward. By doing so, the height of the entire motor case 39 can be ensured (the height H2 is ensured to be larger than the height H1 of the motor case 15 in the conventional example of FIG. 10), and interference with the crawler shoe 37a can be avoided while ensuring the strength and rigidity of the motor case 39.

[0041] Furthermore, in the present embodiment, in addition to the inclined surface portion 39g described above, a parallel surface portion 39h is provided inside the inclined surface portion 39g in the left-right direction. This parallel surface portion 39h forms a surface parallel to the main body 37b of the crawler shoe 37a located above it in the left-right direction. That is, the upper surface 39d of the motor case 39 is directed inward in the left-right direction and approaches the main body 37b of the upper crawler shoe 37a at the inclined surface portion 39g. However, when it reaches the parallel surface portion 39h further inward, it does not approach the main body 37b of the crawler shoe 37a on the inner side therefrom.

[0042] If the entire upper surface of the motor case is configured as an inclined surface portion that slopes upward toward the inside, it is necessary to set the inner end portion in the left-right direction to a height that does not interfere with the upper crawler shoe. As a result, the entire upper surface becomes lower than the lower surface of the main body of the crawler shoe, and the overall height of the motor case is limited accordingly. On the other hand, if a parallel surface portion 39h is provided inside the inclined surface portion 39g as in the present embodiment, the area (parallel surface portion 39h) set to the maximum height that does not interfere with the upper crawler shoe 37a on the upper surface 39d of the motor case 39 becomes larger, and the height of the entire motor case 39 can be ensured more effectively.

[0043] Also, the crawler carrier 100 of the present embodiment has features in the mounting structure of the ground roller 36 on the side frame 33 when compared with the examples shown in FIGS. 8 to 10.

[0044] As shown in FIG. 6, the grounding roller 36 is swingably attached to an attachment bracket 33b connected to the lower part of the side frame 33 via a swing pin 36a. The swing pin 36a is inserted into the attachment bracket 33b so as to penetrate it in the left-right direction (the direction perpendicular to the plane of FIG. 6). Further, a swing bracket 36b is attached to the swing pin 36a in a manner suspended therefrom. The upper part of the swing bracket 36b is penetrated by the swing pin 36a together with the attachment bracket 33b in the left-right direction, and is installed so as to be swingable back and forth about the swing pin 36a with respect to the attachment bracket 33b. A pair of grounding rollers 36 are rotatably attached to the lower part of the swing bracket 36b via roller shafts 36c in the front-rear direction. In the case of this embodiment, for each side frame 33 constituting one crawler 32, a set including one attachment bracket 33b, one swing pin 36a, one swing bracket 36b, and two front and rear grounding rollers 36 is provided in four in the front-rear direction.

[0045] Each attachment bracket 33b is a component having a shape as shown in FIG. 7, and includes a cylindrical portion 33c as a pin insertion portion for inserting the swing pin 36a, and flange portions 33d provided at both ends of the cylindrical portion 33c.

[0046] The cylindrical portion 33c is a cylindrical member with both ends open, into which the swing pin 36a (see FIG. 6) is inserted. The flange portion 33d is a member that forms a surface perpendicular to the axial direction from both ends of the cylindrical portion 33c and projects upward. The distance between the flange portions 33d provided at both ends of the cylindrical portion 33c is set such that the lateral width of the side frame 33 just fits between the two flange portions 33d. Further, in some of the attachment brackets 33b (two attachment brackets 33b located in the middle in the front-rear direction) among the four attachment brackets 33b attached to one side frame 33, as shown in the center of FIG. 7, a notch portion 33e cut from the upper side downward is formed in the upper part of the flange portion 33d.

[0047] When attaching the mounting bracket 33b to the side frame 33, the mounting bracket 33b is arranged with respect to the side frame 33 so as to sandwich the lower part of the side frame 33 from both the left and right sides by a pair of flange portions 33d, and the periphery of the flange portion 33d in contact with both side surfaces of the side frame 33 is welded.

[0048] In this way, in the case of this embodiment, the structure of the portion of the side frame 33 where the swing pin 36a is attached is formed as a component (mounting bracket 33b) separate from the side frame 33 main body. In the structure of a conventional crawler, for example, as shown in FIG. 8, a portion for attaching a swing pin is provided at the lower part of the side frame 9 main body. In such a form, the attachment position of the swing pin is fixed when the side frame 9 main body is manufactured. Therefore, when manufacturing the side frame 9, high precision is required regarding the attachment position of the swing pin. However, if the method of manufacturing the mounting bracket 33b separately from the side frame 33 main body and then attaching it to the side frame 33 later is adopted as in this embodiment, the attachment position of the swing pin 36a with respect to the side frame 33 can be changed when attaching the mounting bracket 33b. Thus, high precision is not required for manufacturing the side frame 33, and the swing pin 36a can be attached to the side frame 33 at the correct position with high precision.

[0049] Also, in a part of the mounting bracket 33b, the notch portion 33e provided at the upper part contributes to the weight reduction of the side frame 33 by reducing the material of the flange portion 33d by the amount of the notch portion 33e. In addition, by taking a longer periphery of the mounting bracket 33b which is the welding target, it also functions to maintain the connection strength of the mounting bracket 33b by welding.

[0050] As described above, in the present embodiment, a crawler 32 including a side frame 33 attached to the left and right of a lower frame 31, a starting wheel 34 attached together with a traveling motor 38 to the front end of the side frame 33, a motor case 39 that houses the traveling motor 38, a grounding roller 36 attached to the lower part of the side frame 33, and a crawler 37 provided so as to surround the side frame 33, the starting wheel 34, and the grounding roller 36 is provided in a lower frame structure of a construction machine for a traveling body 30. A crawler shoe 37a that constitutes the crawler 37 includes an engaging portion 37c that protrudes inside a main body 37b and meshes with the starting wheel 34. On an upper surface 39d of the motor case 39, a sloped surface portion 39g having a gradient that rises as it goes inward in the left - right direction is provided at a position corresponding to below the engaging portion 37c of the crawler shoe 37a positioned above. In this way, in a portion where the engaging portion 37c protrudes downward from the upper crawler shoe 37a, the height of the upper surface 39d is lowered, and in the inner side in the left - right direction from that position, it is made higher, so that while ensuring a height H2 and ensuring the strength and rigidity of the motor case 39, interference between the motor case 39 and the crawler shoe 37a can be avoided.

[0051] Further, in the lower frame structure of the construction machine of the present embodiment, the upper surface 39d of the motor case 39 further includes a parallel surface portion 39h that extends inward in the left - right direction with respect to the sloped surface portion 39g and forms a surface parallel to the main body 37b of the crawler shoe 37a positioned above. In this way, while avoiding interference between the motor case 39 and the crawler shoe 37a, the height of the motor case 39 can be more effectively ensured.

[0052] Further, in the lower frame structure of the construction machine of the present embodiment, the sloped surface portion 39g and the parallel surface portion 39h are integrally formed as continuous plate materials with each other. In this way, the strength of the upper surface 39d in the motor case 39 can be suitably maintained.

[0053] In addition, in the lower frame structure of the construction machine according to the present embodiment, an attachment bracket 33b is provided which is connected to the lower part of the side frame 33, and the grounding roller 36 is rotatably attached to a swing bracket 36b which is swingably supported via a swing pin 36a below the attachment bracket 33b. In this way, the swing pin 36a and the grounding roller 36 can be suitably attached to the side frame 33.

[0054] Therefore, according to each of the above embodiments, it is possible to secure the height of the motor case while avoiding interference between the motor case and the crawler.

[0055] Note that the lower frame structure of the construction machine of the present invention is not limited to the above-described embodiments. For example, the construction machine to which the present invention is applied is not limited to a swing-type crawler carrier, and can be applied to various vehicles as long as it is a construction machine equipped with a crawler-type traveling body. In addition, various modifications can be made within the scope of the gist of the present invention in the implementation of the present invention.

Explanation of reference numerals

[0056] 30 Traveling body 31 Lower frame 32 Crawler 33 Side frame 33b Attachment bracket 34 Drive wheel 36 Grounding roller 36a Swing pin 36b Swing bracket 37 Crawler belt 37a Crawler shoe 37b Body 37c Meshing portion 38 Traveling motor 39 Motor case 39d Upper surface 39g Inclined surface 39h Parallel surface

Claims

1. The side frames are attached to the left and right of the lower frame, A drive wheel attached to the front end of the side frame together with a travel motor; a motor case that houses the driving motor; A ground roller attached to a lower portion of the side frame; a crawler provided to surround the side frame, the drive wheel, and the ground contact roller; A lower frame structure of a construction machine having a crawler configured as a traveling body, The crawler shoe constituting the crawler belt has a meshing portion that protrudes inwardly of the main body and meshes with the drive wheel, A slope portion is provided on the upper surface of the motor case, the slope portion being inclined upward from a position below the meshing portion of the crawler shoe located above toward the inside in the left-right direction. The lower frame structure of construction machinery is characterized by the above.

2. The upper surface of the motor case further includes a parallel surface portion that extends inward in the left-right direction with respect to the inclined surface portion and forms a surface parallel in the left-right direction with the main body of the crawler shoe located above.

2. The lower frame structure of claim 1, wherein

3. The inclined surface portion and the parallel surface portion are integrally formed as a continuous plate material.

3. The lower frame structure for a construction machine according to claim 2 .

4. A mounting bracket is provided which is connected to a lower portion of the side frame, The ground contact roller is rotatably attached to a swing bracket that is swingably supported below the mounting bracket via a swing pin.

2. The lower frame structure of claim 1, wherein

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