JPH0349164Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a base frame of a hydraulic excavator.

Conventional technology As shown in Figure 6, a hydraulic excavator has front 1,
It is composed of a lower traveling body 2, an upper rotating body 3 (including a swing frame 5), and a cabin 4.
Further, since the upper rotating body 3 has a 360° turning function and at the same time has forward/backward traveling, spin turn, and pivot turn traveling functions, the lower traveling body 2 has a configuration as shown in FIG. 7. That is, the lower traveling body 2 includes a base frame 6 as the main member, a swing bearing 7 for joining with the upper rotating body 3, a sprocket 9 driven by a motor, a track assembly 10 that is in contact with the ground and converts rotation into forward motion, and a track. It is composed of an idle wheel 8 that supports and adjusts the assembly 10, a lower roller 12 that supports the base frame 6 together with the idle wheel 8 and sprocket 9, and an upper roller 11 that supports the track assembly 10.

The base frame 6 mainly consists of a car body 13, a truck frame 14, and a traveling motor support 15, as shown in FIG. The track frame 14 has a thin plate open section structure and is connected to the motor support 15 via a flange. The idle wheel support section 20 has a swing mechanism. The main frame 1 of the car body 13 is a thin box-shaped closed structure.
6, a cylindrical portion 17 mounted thereon, and a flange 18 for mounting a bearing.
The conventional base frame adopts a coupling method in which the car body 13 has a #-digit structure type and rides on the truck frame 14. This is caused by the fact that the ground conditions at the excavator operation site are uneven and the lower surface of the car body 13 needs to have an appropriate ground clearance H to avoid obstacles on the ground.

The external forces applied to the base frame 6 are the load A that transmits the movement of the front 1 and upper rotating body 3 via bearings, and the load B that is applied from the bottom of the idle wheel 8 or sprocket 9 when the vehicle body swings due to uneven ground conditions. However, according to the analysis results up to now, the load B has become critical for the base frame 6.

In the case of load B, when a single point concentrated load 2P is applied to the idle wheel 8, the frame is analyzed by modeling the base frame and the bending torsional rigidity of the main frame 16 of the truck frame 14 and the car body 13, and the load generated on each member is analyzed. The loads and loads are shown in Figure 9.
Here, a, b, and l represent the lengths between the load points of the truck frame 14 and the main frame 16 of the car body 13, and E, G represent the longitudinal elastic modulus and the transverse elastic modulus.
Ia, Ib, Il, Ja, Jb, and Jl indicate the specifications of each bending stiffness and torsional stiffness. Further, My, X, and Tx represent the bending moment, shear force, and torsion moment generated at the center of the truck frame 14. The load value generated by this is as shown in the lower part of Fig. 9.

As shown in Fig. 9, the intersection 19 (see Fig. 8) between the truck frame 14 and the car body 13 is a place where complex loads are applied and high local stress is generated, requiring caution. It has a structural type.

Problems to be solved by the invention The conventional device described above has the following drawbacks: Because the carbide 13 has a # girder straight beam structure, the distance from the load point (a in Fig. 9) is large. At this point, the bending moment at the intersection 19 becomes large.

The load from the idle wheel 8 or sprocket 9 is transmitted by the bending and torsional rigidity distribution of the main frame 16 and the track frame 14 to generate a member load.

The intersection 19 has a complicated structure.

Since the car body 13 is a #-shaped press structure on which the car body 13 rests on the truck frame 14, it is difficult to obtain a sufficient ground clearance H due to the height restriction of the truck frame.

From the above, the current base frame structure has a large number of parts, increasing costs, and at the same time has a ground clearance H for avoiding obstacles.
I can't get enough.

Measures to solve the problem: In order to reduce the internal force at the intersection of the car body and truck frame, the connection point of the car body frame and truck frame must be located at an extreme distance from the idle support part and motor support part on the truck frame. The frame of the car body and the truck frame are joined together so that the frame becomes smaller.

The structure is such that the car body frame is directly connected to the idle support section and motor support section of the truck frame via the upper and lower flanges, allowing block construction of the entire base frame.

The cylindrical part of the car body is divided into a bearing support cylindrical part and a cylindrical frame. Also, the upper and lower flanges of the car body frame are curved downward to increase the ground clearance H.

The central beam of the truck frame 41 does not require a large degree of rigidity for its function, so it is made of a beam with the lowest possible rigidity.

Effect: Since the internal force generated at the intersection of the car body and the truck frame is reduced, the required strength of the base frame is reduced.

Since the rear flange of the carbide is curved upward, the ground clearance H increases.

Embodiment In FIGS. 1 to 5, the base frame 3
1 consists of a central car body 32 and left and right truck frames 41.

The lower flange 49 of the car body 32 is curved downward in the vicinity of the truck frame 41 and at the same time widens, and the central portion is cut out in a circular shape. A thin cylindrical frame 3 is attached to the lower flange 49.
4 is placed on top of which the upper flange 35 is placed.
The upper flange 35 of the car body 32 is bent downward in the vicinity of the truck frame 41 and at the same time expands, with a circular cutout in the central portion. A bearing support cylindrical part 38, which is a thin cylinder, is placed on top of the upper flange 35, and a bearing support flange 39 is attached thereon. side plate 36,
37 has its inner end joined to the cylindrical frame 34, and together with the upper flange 35 and lower flange 49 forms four beam-like frames 40 with closed cross sections. Side plates 36, 37 and upper and lower flanges 35, 49 are connected to idle support flange 44 and motor support flange 45 of truck frame 41, respectively.

On the other hand, the truck frame 41 has an intermediate beam 46,
It consists of an idle wheel support part 42 and a motor support part 43, an intermediate beam 46 is connected to the side plate 36, and the support parts 42 and 43 are connected to an idle support flange 44 and a motor support flange 4.
It is combined with 5. However, the intermediate beam 46 has a modified open section structure (ⓓ) in which the upper side is narrow, the lower side is widened, and the lower part is not connected, and a support flange 47 for the lower roller (12 in FIG. 7) is attached to the lower part.

In such a device, the bending rigidity of the intermediate beam 46 of the truck frame 41 is weak against the typical concentrated load applied from the bottom by the idle wheel (8 in FIG. 7) and the sprocket (9 in FIG. 7), and at the same time the flange Since the load point is directly aligned with the frame 40 of the car body 32 via 44 and 45, most of the concentrated load is transmitted to the frame 40.

The load entering from the upper rotating body (3 in Figure 6) is transmitted to the flange 39 via the swing bearing (7 in Figure 7), absorbed by the bearing support cylindrical part 38, and then transferred to the cylindrical frame 34, the upper flange 35, and the lower part. It is absorbed by the radial beams made up of the flange 49 and the side plates 36 and 37.

Effects of the invention The frame of the car body has a radial structure (spider structure), and the concentrated load from below is directly transmitted to the frame of the car body, which reduces the internal force at the intersection. 2) it has a simpler structure; and 3) the structural calculation method becomes clearer.

As a result of the above, compared to conventional base frames, the entire base frame of the present invention including intersections is simpler, and the number of parts is reduced by approximately 45%, resulting in a significant cost reduction.

According to the present invention, the block construction method becomes possible and manufacturing becomes easy.

[Brief explanation of the drawing]

Figure 1 is a perspective view of an embodiment of the base frame of the hydraulic excavator of the present invention, Figure 2 is a plan view of the same (only one side is shown as it is symmetrical), Figures 3 and 4.
The figure is a side view of the same as the above, and FIG. 5 is a front view of the same. Fig. 6 is an overall view of the hydraulic excavator, Fig. 7 is a configuration diagram of the lower traveling body, Fig. 8 is a perspective view of the conventional device,
FIG. 9 is an analysis diagram of the external force and load on the base frame when the vehicle body is rocking. 31...Base frame, 32...Car body, 34...Cylindrical frame, 40...Beam frame, 41...Truck frame, 42...Idle wheel support section, 43...Motor support section, 46...Intermediate beam .

Claims (1)

[Scope of utility model registration request] It consists of a central car body and left and right truck frames, the car body is made up of a central cylindrical frame and four beam-shaped frames extending radially from the cylindrical frame, and the truck frame includes front and rear idle wheel support parts, The car body is composed of a motor support part and a central intermediate beam, and the beam-like frame of the car body is curved downward and its outer end is directly connected to the flanges of the idle wheel support part and the motor support part of the truck frame. The base frame of a hydraulic excavator.