CN111688861B

CN111688861B - Frame assembly for vehicle

Info

Publication number: CN111688861B
Application number: CN202010169625.6A
Authority: CN
Inventors: C·R·阿斯温克马尔; M·苏达山; M·苏巴什
Original assignee: TVS Motor Co Ltd
Current assignee: TVS Motor Co Ltd
Priority date: 2019-03-16
Filing date: 2020-03-12
Publication date: 2022-01-28
Anticipated expiration: 2040-03-12
Also published as: CN111688861A

Abstract

The present subject matter relates generally to a two or three wheeled vehicle and, more particularly, to a frame assembly for a two or three wheeled vehicle. The frame assembly (102) includes: a pair of rear frames (202) extending rearward from the main frame (201); a pair of side frames (203) extending downward from at least a portion of the pair of rear frames (202); a reinforcement member (204) adjacently disposed between at least a portion of the pair of rear frames (202), the reinforcement member (204) being configured to connect the pair of rear frames (202) and the pair of side frames (203); and a shock absorber mounting shaft (205) attached to at least a portion of the reinforcement member (204), the shock absorber mounting shaft (205) including a varying section A, B, C.

Description

Frame assembly for vehicle

Technical Field

The present subject matter relates generally to a two or three wheeled vehicle and more particularly, but not exclusively, to a frame assembly for a two or three wheeled vehicle.

Background

Generally, in a two-or three-wheeled vehicle having a frame assembly, the frame assembly extends in the longitudinal direction of the vehicle. The frame assembly serves as both a structural member and a load-bearing member of the vehicle. Also, the drive wheel and the driven wheel are supported by the frame assembly. In a saddle-ride type vehicle, the power unit is mounted to the frame assembly or suspended to the frame assembly at a low position. Typically, the wheel is connected to the frame by a damping member. Further, in a vehicle having a striding portion, a power unit is swingably mounted to a frame assembly through a damping member, typically a suspension. Thus, the forces acting on the frame assembly are large due to the extra weight of the power unit on the rear portion. The suspension plays a crucial role in damping forces acting on the wheel and preventing forces from the power unit from reaching the frame assembly.

Drawings

A detailed description of the present subject matter is described with reference to the accompanying drawings. The same reference numbers are used throughout the drawings to reference like features and components.

Fig. 1 shows a saddle type saddle-ride type vehicle.

FIG. 2 illustrates an exemplary frame assembly for a two-wheeled vehicle.

Figure 3 shows a shock absorber mounted on a frame assembly of a two-wheeled vehicle.

Fig. 4(a) shows an embodiment of at least one reinforcement member.

Fig. 4(b) shows a side view of the shock absorber mounting shaft.

Fig. 4(c) shows a side view of a cross-sectional view of the shock absorber mounting shaft shown in fig. 4 (b).

FIG. 5(a) shows a top view of a vehicle frame assembly according to an embodiment of the present invention.

Fig. 5(b) and 5(c) show cross-sectional views of the damper mounting shaft mounted on at least a portion of the reinforcement member.

Fig. 6(a) and 6(b) show comparative studies of stress line flow along a shock absorber mounting shaft without and with the addition of the proposed non-anchoring flange, respectively.

Detailed Description

Typically, in a vehicle, the frame assembly includes a front region and a rear region. The forward region supports the steering assembly together with the front suspension of the vehicle. The front region includes a primary tube that provides rigidity and strength to withstand forces acting thereon. The rear region supports a vehicle component including a power unit and a powertrain, a rear wheel, and a rear suspension connected thereto. Thus, the rear region is subjected to various forces from the rear wheels through the suspension and from the power unit. For example, impacts from the road (e.g., bumps) and vibrations from the power unit also act on the frame assembly. Moreover, the vehicle is provided with utility and styling components mounted to the frame assembly to provide utility space and aesthetics, which components will be installed with minimal modification.

To this end, various vehicle components, such as the rear suspension, a tool box mounted to the frame assembly, require a plurality of reinforcement members welded to the frame assembly. Furthermore, providing multiple reinforcement members requires multiple welds, which increases stress concentration and also reduces strength at the particular point on the localized area. Moreover, multiple welds in the vicinity cause dimensional changes in the frame assembly, thereby affecting the assembly/installation of the components therein. For example, any dimensional changes in the frame assembly can affect the mounting location of the hanger bracket or the tool box. Since the components, such as the toolbox or the hanger bracket, are rigid components with fixed mounting points, the above variations will result in interference or gaps between the components. Thus, the hard-points (which are the requisite load-bearing points) are subjected to various forces, and any dimensional change at the hard-points will further affect the strength of the particular points. Furthermore, the driving characteristics of the vehicle region can be impaired, since variations can affect the mounting orientation of the vehicle components. For example, dimensional changes may affect the installation of a rear suspension that is mounted to a hard-point of a vehicle. This can affect the ride characteristics of the vehicle because the functional characteristics of the suspension change due to improper orientation and alignment. Further, the suspension is mounted to a single member of the frame assembly. Thus, such variations can affect the life of the frame assembly as the force bearing points are subjected to forces, resulting in failure due to forces acting on the individual components. The frame-mounted shock absorbers are a very important part designed to take up the load and provide adequate ride comfort during the action of the shock absorbers, under road vehicle driving conditions or when riding in bumps or potholes with a predetermined payload.

There are various types of configurations of shock absorber mounts in two-wheeled vehicles. All configurations are designed to provide the shock absorber function as described above, but with slightly different types of load carrying capacity based on vehicle requirements. A first type of shock absorber mount design includes a shock absorber and a mounting member that supports on both sides and provides a fixed support that is designed to primarily withstand shear loads. A second shock absorber mount design includes a shock absorber supported on one side by a fastened mounting member and secured on the other side by a mounting nut, which is of the cantilever type and which is subject to large bending loads. The third type of shock absorber mount design is the most common one, which has free support at both ends. It consists of a shock absorber and a mounting member with varying shaft sections on a fixed plate that provides support on both sides. This type of mounting design is both bending and shear load bearing and is typically used for vehicles that are highly loaded. In the existing design of the third type of shock absorber mount, the shock absorber mounting bosses are welded to the frame gussets on both sides. The side facing the inside of the gusset of the frame bears the load in a uniform manner and effectively disperses the load. The side facing the welded outer part of the frame gusset has some difficulty in load distribution and therefore the stress is concentrated toward this end. There are mainly two weak areas. In one of the regions, the shock absorber mounting shaft is welded to a frame gusset that hardens due to the heat of the weld. Another area of weakness is a sharp transition area on the shock absorber mounting shaft where stress concentrations are high. These two areas of weakness are very close to each other on the shock absorber mounting shaft, which results in areas of very high stress. During fatigue loading, the shock absorber mounting shaft may fail in these areas due to shear or brittle cracking due to indentation and tilt effects. Accordingly, a challenge is to provide a frame assembly for the mounting of vehicle components with minimal changes, and at the same time the frame assembly should be able to provide structural strength. It is an object of the present subject matter to provide an improved design of the shock absorber mounting area.

The present subject matter relates to improving frame design through improvements to the shock absorber mounting area. By ensuring that the stress concentration is evenly distributed throughout the frame structure, the load bearing capacity can be significantly improved.

According to an embodiment of the present invention, the frame assembly includes a pair of rear frames. The pair of rear frames extend obliquely rearward and are joined by at least one cross member. Further, a pair of side frames extend obliquely downward from at least a portion of the pair of rear frames. At least one reinforcement member is attached as a joining means between at least a part of the pair of rear frames and the pair of side frames. According to one embodiment, the at least one reinforcement member is fixedly attached, e.g. welded, between at least a portion of the pair of rear frames and the pair of side frames.

Further, the rear portion of the frame assembly is suspended by at least one rear suspension. At least one rear suspension is attached between at least a portion of the pair of rear frames and the rear wheels of the vehicle. According to one embodiment of the invention, at least one rear suspension is mounted to the shock absorber mounting shaft. The shock absorber mounting shaft is fixedly attached to at least a portion of at least one reinforcement member attached between the pair of rear frames and the pair of side frames.

According to an embodiment of the present invention, the shock absorber mounting shaft includes a non-anchoring flange region having a wider contact surface. The wider contact surface provides an increased area for attachment with at least a portion of the frame as compared to conventional attachment portions. The increased contact surface for attachment therebetween prevents indentation or canting effects. Such non-anchoring flanges improve the stress flow distribution in the weaker regions of the shaft.

According to an embodiment of the invention, the shock absorber mounting shaft includes varying sections A, B, C, and each section is configured to meet a specific function. The mounting shaft supports the shock absorbers on the left and right sides of the vehicle. In particular, section a is welded to at least one reinforcement member on both sides of the frame, section B houses at least a portion of the shock absorber, and section C has a threaded profile and is fastened by means of a dome nut.

In addition, the shock absorber mounting shaft includes an unanchored flange to improve the area of weakness. The non-anchoring flange includes a wider contact surface than conventional mounting shafts, thereby increasing the weld area such that indentation or canting effects are reduced. The non-anchoring flange added to the segmented section a, a2, helps to segment the local stress region into a1 and a2, thereby reducing the stress flow levels that occur in the local region. The non-anchored flange also isolates the weld projection and weld branding from portions of the frame and the at least one reinforcement member, which further improves welding away from the stress region and mitigates the effects of indentation and tilting.

According to another embodiment of the invention, the non-anchoring flange also ensures maximum surface contact with the back seat armrest mounting bracket, thereby eliminating the need for additional washers for surface contact.

The division areas a1 and a2 as described above ensure that the run-out lengths of sections a and B are cut short so that better axial loads and bending moments are carried due to the reduced length.

In addition, the addition of a non-anchoring flange area on the mounting shaft provides uniform stress distribution throughout the shaft and allows stress lines to be directed to flow smoothly and evenly away from the usual stress concentration areas on the mounting shaft.

Typically, the shock absorber mounting area on the frame is comprised of a shock absorber, a mounting shaft and at least one reinforcement member. At least one reinforcement member is welded to the pair of rear frames and the pair of side frames. The close weld area in the at least one reinforcement member requires venting of the damper mounting shaft to relieve some of the stress in the weld area. The addition of the blind holes helps provide venting and corner crack arrest to the at least one reinforcement member so that loads are not directly transferred to the at least one reinforcement member.

The design of the blind hole is chosen such that K: l and K': the ratio of L' is about 2: 1, where K is the shaft width between the welds and L is the width of the blind hole, and K 'is the diameter of the shaft and L' is the diameter of the blind hole. Furthermore, the depth of the blind hole is achieved by the cold forging technique, so that there are no internal voids and a uniform grain structure is obtained.

Further, according to embodiments of the present invention, the blind holes are configured to provide flexibility to the mounting area while bearing a load and allow a particular area or mounting shaft to return to its original shape. The depth (L) of the blind hole is about 1/2 of the depth (K) of the shaft between the welds, and the length (L ') of the blind hole is 1/2 of the shaft length (K').

Furthermore, according to a preferred embodiment, the blind holes are realized by a cold forging technique, such that the grains in the material are aligned along stress flow lines. This also helps to improve stress flow concentration during load conditions, such that stresses on the at least one reinforcement member are mitigated.

The stress concentration coefficient Kt is a parameter for determining the stress of a local region. The coefficient depends on the parameters, the larger diameter "D", the smaller diameter "D", the trailing arm height "h" — (D-D)/2, the transition radius r, and the load "P" applied to the shaft. By optimizing the above parameters and the ratio of D/D and r/D, stress concentration can be reduced.

According to a preferred embodiment, the optimum transition radius value is selected to have the lowest stress concentration and the largest surface contact with the mating bracket or washer. The radius improvement also helps to reduce stress concentrations at the transition corners and to smooth out flow lines when the stress flows in the material. Thus, the modified design has optimized D/D and r/D ratios such that stress concentrations are reduced to a minimum level at the transition radius and surface contact with the shock absorber is increased to a maximum level.

By effectively varying the cross-sectional area, the concentrated stress streamlines are made smoother, so that by improving the cross-section and reducing the stress concentration coefficient in local areas, nominal and maximum stresses can be reduced by about three times.

This type of design ensures a better distribution of the load in the shock absorber mounting area and that the frame does not crack or shear even in the event of a failure of the shock absorber.

Additionally, according to another embodiment of the present invention, the proposed damper mounting shaft design also helps to improve surface contact with the damper eye and the back seat armrest support during vehicle use.

Further, according to another embodiment of the present invention, the at least one reinforcement member connects and supports the pair of rear frames and the pair of side frames, and also supports the shock absorber mounting shaft such that the at least one reinforcement member bears a part of the load from the shock absorber and the mounting shaft.

At least one reinforcement member is provided with a predetermined crack stop region at a junction of the pair of rear frames and the pair of side frames. The improvement of at least one reinforcement member is such that the weld loss zone at the point of convergence is closed and further expands the embossments to the sides to orderly distribute and distance the stress flow away from the center.

Furthermore, the area moment of inertia can be significantly improved by adding non-anchoring flanges and blind holes which help to achieve a uniform cross-sectional area and reduce the shaft's protrusion length.

Furthermore, by adding non-anchoring flanges and blind holes, the nominal stress decreases with increasing cross-sectional area. The maximum stress decreases with decreasing stress concentration factor.

These and other advantages of the present subject matter will be described in more detail in the following description in conjunction with the accompanying drawings.

Fig. 1 shows a saddle-ride type vehicle 100, which is an exemplary motor vehicle, having an IC engine 101 arranged vertically. Preferably, the IC engine 101 is a single cylinder type IC engine. The two-wheeled vehicle includes a front wheel 110, a rear wheel 103, a frame assembly 102, a fuel tank 121, and a seat assembly 105. The frame assembly 102 includes a head tube 111, a main tube (not shown), a down tube (not shown), and a seat rail (not shown). The head pipe 111 supports a steering shaft (not shown), and two telescopic front suspensions 114 (only one shown) are attached to the steering shaft by a lower bracket (not shown). A pair of telescoping front forks 114 are covered by a front fender 115, and the front fender 115 is mounted to a lower portion of the telescoping front suspension 114 at the steering shaft end. Handlebar 108 is fixed to an upper bracket (not shown) and can rotate to both sides. A headlight assembly 109, a sun visor cover (not shown), and an instrument panel (not shown) are provided at an upper portion of the head pipe 111. The down tube may be located in front of the IC engine 101 and extend obliquely downward from the head pipe 111. The main pipe is located above the IC engine 101 and extends rearward from the head pipe 111. The IC engine 101 is mounted at the front through a down pipe, and the rear of the IC engine 101 is connected at the rear portion of the main pipe.

The fuel tank 121 is mounted on a horizontal portion of a main pipe (not shown). A rear swing arm (not shown) is connected to the frame assembly 102 to swing vertically, and a rear wheel 103 is connected to a rear end of the rear swing arm 118. Typically, the rear swing arm is supported by a rear suspension 117. A tail light unit (not shown) is disposed at the end of the two-wheeled vehicle at the rear of the seat assembly 105. Armrests 106 are also provided at the rear of the seat rail. The rear fender 127 is disposed above the rear wheel 103.

FIG. 2 illustrates an exemplary frame assembly for a two-wheeled vehicle. The frame assembly 102 includes a head pipe 111, a main pipe 201 extending obliquely downward from the head pipe 111. A pair of rear frames 202 extend rearwardly from at least a portion of the main tube 201. The pair of rear frames 202 are connected across by one or more cross members 206. Further, a pair of side frames 203 extend downward from at least a portion of the pair of rear frames 202. The pair of side frames 203 extends toward the main pipe 201. Further, the connection between the pair of rear frames 202 and the pair of side frames 203 is reinforced by at least one reinforcing member 204. At least one reinforcement member is configured to receive the shock absorber mounting shaft 205. At least one reinforcement member 204 and a shock absorber mounting axle 205 are mounted on the left and right hand sides of the pair of rear frames 202.

Figure 3 shows a shock absorber mounted on a frame assembly for a two-wheeled vehicle. At least one rear shock absorber 117 is mounted on at least a portion of the reinforcement member 204. In particular, the shock absorber mounting shaft 205 is configured to receive at least a mounting portion of at least one rear shock absorber 117, the eye 117 a. The eyelet 117a is mounted to the shock absorber mounting shaft 205 by one or more mounting members 117 b. According to another embodiment of the present invention, at least a portion of the back seat armrest mount 106a is also mounted to the at least one shock absorber mounting shaft 205. The proposed shock absorber mounting shaft 205 provides maximum surface contact with the back seat armrest mount 106a, eliminating additional washers for surface contact. The maximum contact surface also prevents any deformation of the rear seat armrest 106 under vehicle handling conditions, such as when transporting the vehicle or when handling the vehicle in a compact parking space. Furthermore, the co-mounting of the eyelet 117a and the back seat armrest mount 106a eliminates the additional need for a gasket, and a common gasket may be used for the common purpose of mounting the two components.

Fig. 4(a) shows an embodiment of at least one reinforcement member. The at least one reinforcement member 204 includes: a side frame mounting portion 401 configured to be attached to at least a portion of the pair of side frames (not shown); and a rear frame mounting portion 402 configured to be attached to at least a portion of the pair of rear frames. The side frame mounting portions 401 and the rear frame mounting portion 402 are continuous surfaces and provide maximum abutment with the joining portions of the frames, respectively. Such reinforcement members 204 may carry the greatest loads and provide stability to the vehicle components mounted thereon. In addition, at least one reinforcement member 204 includes features that provide structural stability, including the addition of material at areas of greatest stress concentration. In particular, the at least one reinforcement member includes an embossed portion in an area configured to receive a portion of the other vehicle component. The embossed portions of the proposed design are expanded to a wider area to enable stress concentration away from the center of the at least one reinforcement member. In this way, a more stable operation of at least the reinforcement member 204 can be achieved.

Fig. 4(b) shows a side view of the shock absorber mounting shaft. The shock absorber mounting shaft 205 is welded to at least a portion of the at least one reinforcement member 204. According to an embodiment of the present invention, the shock absorber mounting shaft 205 includes a non-anchoring flange area A2 with a wider contact surface. The wider contact surface provides an increased area for attachment with at least a portion of the frame as compared to conventional attachment portions. The increased contact surface for attachment therebetween prevents indentation or canting effects. This non-anchoring flange a2 improves stress flow distribution in the weaker region of the shock absorber mounting shaft 205.

According to an embodiment of the present invention, the shock absorber mounting shaft 205 includes varying sections A1, A2, B, C, and each section is configured to meet a specific function. The shock absorber mounting shaft 205 supports shock absorbers on both the left and right sides of the vehicle. In particular, section a is welded to at least one reinforcement member 204 on both sides of the frame, section B houses at least a portion of the shock absorber, and section C has a threaded profile and is fastened by a dome nut.

In addition, the shock absorber mounting shaft 205 includes an unanchored flange A2 to improve the area of weakness. The non-anchoring flange a2 includes a wider contact surface than the conventional shock absorber mounting shaft 205, thereby increasing the weld area so that the indentation or canting effect is reduced. The addition of the non-anchoring flange a2 to section a helps to divide the local stress region into a1 and a2, thereby reducing the stress flow levels that occur in the local region. The non-anchored flange a2 also isolates the weld projection and weld branding from portions of the frame and the at least one reinforcement member 204, further improving welding away from stress regions and mitigating the effects of indentation and tilting.

According to another embodiment of the present invention, the non-anchoring flange a2 also ensures maximum surface contact with the back seat armrest mounting bracket interface, thereby eliminating additional washers for surface contact.

In addition, the addition of the non-anchoring flange a2 area on the shock absorber mounting shaft 205 provides a uniform stress distribution throughout the shaft 205 and allows stress lines to be directed to flow smoothly evenly away from the usual stress concentration areas on the mounting shaft.

Fig. 4(c) shows a side view of a cross-section of the shock absorber mounting shaft as shown in fig. 4 (b). Typically, the shock absorber mounting area on the frame is comprised of a shock absorber, a mounting shaft 205 and at least one reinforcement member 204. At least one reinforcement member 204 is welded to the pair of rear frames and the pair of side frames. The closed weld area in the at least one reinforcement member 204 requires venting on the shock absorber mounting shaft 205 to relieve some of the stress on the weld area. The addition of the blind holes 403 helps provide venting and corner crack arrest to the at least one reinforcement member 204 so that loads are not transferred directly to the at least one reinforcement member 204.

The design of the blind hole 403 is chosen such that K: l and K': the ratio of L' is about 2: 1, where K is the width of the shaft 205 between the welds, and L is the width of the blind bore 403, and K 'is the diameter of the shaft 205, and L' is the diameter of the blind bore 403. Further, the depth of the blind hole 403 is achieved by a cold forging technique so that there are internal voids and a uniform grain structure is obtained.

Further, according to embodiments of the present invention, the blind holes 403 are configured to provide flexibility to the mounting area while carrying the load and allow a particular area or mounting shaft 205 to return to its original shape. The depth (L) of the blind hole is about 1/2 of the depth (K) of the shaft between the welds, and the length (L ') of the blind hole is 1/2 of the length (K') of the shaft.

Furthermore, according to a preferred embodiment, the blind holes 403 are realized by a cold forging technique, so that the grains in the material are aligned along the stress flow lines. This also helps to improve stress flow concentration during loading conditions to relieve stress on the at least one reinforcement member 204.

According to an embodiment of the present invention, the shock absorber mounting shaft 205 includes a varying cross-section of decreasing diameter as compared to the diameter of the non-anchoring flange. Either side of the non-anchoring flange includes a cross-section of decreasing diameter. In a preferred embodiment, the shock absorbing mounting shaft 205 is a stud or pin.

According to an embodiment of the present invention, the shock absorber mounting shaft 205 includes a non-anchor pin A2 disposed at about a middle portion. As such, the shock absorber mounting shaft 205 includes a blind hole 403 on the inboard side toward the portion of the shock absorber mounting shaft 205 that is attached to the reinforcement member 204 and includes a threaded configuration on the outboard side. The threaded configuration is configured to receive at least one shock absorber 117. The shock absorber mounting shaft 205 includes varying transverse sections a1, a2, B and C, which provide synergy, i.e., different decreasing diameters on either side of the non-anchoring flange a2, a blind hole 403 on the inside, and a threaded configuration on cross section C. This provides compatibility with blind vias while preventing plastic deformation of certain areas.

FIG. 5(a) shows a top view of a vehicle frame assembly according to an embodiment of the present invention. The shock absorber mounting shafts 205 are attached to both sides of a pair of rear frames 202 of the vehicle frame assembly 102. Fig. 5(b) and 5(c) show cross-sectional views of the damper mounting shaft mounted to at least a portion of the reinforcement member. Typically, the shock absorber mounting area on the frame is comprised of the shock absorber 117, the mounting shaft 117a and at least one reinforcement member 204. At least one reinforcement member 204 is welded to the pair of rear frames 202 and the pair of side frames. The closed weld area in the at least one reinforcement member 204 requires venting on the damper mounting shaft 205 to relieve some of the stress on the weld area. The addition of the blind holes 403 helps provide venting and corner crack arrest to the at least one reinforcement member 204 so that loads are not transferred directly to the at least one reinforcement member 204.

The blind hole 403 design is chosen such that K: l and K': the ratio of L' is about 2: 1, where K is the width of the shaft 205 between the welds, and L is the width of the blind hole 403, and K 'is the diameter of the shaft 205, and L' is the diameter of the blind hole 403. Further, the depth of the blind hole 403 is achieved by a cold forging technique so that there are internal voids and a uniform grain structure is obtained.

Furthermore, according to a preferred embodiment, the blind holes 403 are realized by a cold forging technique, so that the grains in the material are aligned along the stress flow lines. This also helps to improve stress flow concentration during loading conditions to relieve stress on the at least one reinforcement member.

The stress concentration coefficient Kt is a parameter for determining the stress of a local region. The coefficient depends on the parameters, the larger diameter "D", the smaller diameter "D", the trailing arm height "h" — (D-D)/2, the transition radius r, and the "P" of the load applied to the shaft. By optimizing the above parameters and the ratio of D/D and r/D, stress concentration can be reduced.

Fig. 6(a) and 6(b) show comparative studies of stress line flow along a shock absorber mounting shaft without and with the addition of the proposed non-anchoring flange, respectively. As shown in fig. 6(a), the side facing the outside of the frame weld has some difficulty in load distribution, and therefore stress concentrates toward this end. There are mainly two weak areas. In one of the regions, the damper mounting shaft 205 is welded to at least one reinforcement member that hardens due to the heat of the weld. Another area of weakness is a sharp transition area on the shock absorber mounting shaft 205 where stress concentrations are high. These two areas of weakness are very close to each other on the shock absorber mounting shaft 205, which results in an area of very high stress. During fatigue loading, the shock absorber mounting shaft 205 may fail in these areas due to shear or brittle fracture due to indentation and tilt effects. However, as shown in FIG. 6(b), the shock absorber mounting shaft 205 includes a non-anchoring flange region A2 with a wider contact surface. The wider contact surface provides an increased area for attachment with at least a portion of the frame as compared to conventional attachment portions. The increased contact surface for attachment therebetween prevents indentation or canting effects. Such non-anchoring flanges improve the stress flow distribution in the weaker regions of the shaft.

The non-anchoring flange 403 includes a wider contact surface than the conventional shock absorber mounting shaft 205, thereby increasing the weld area to reduce the indentation or canting effect. The addition of the non-anchoring flange 403 to section a helps to divide the local stress region into a1 and a2, thereby reducing the stress flow levels occurring at the local region. The non-anchored flange 403 also isolates the weld projection and weld branding from portions of the frame and the at least one reinforcement member 204, further improving the weld away from the stress region and mitigating the effects of indentation and tilting.

According to another embodiment of the invention, the non-anchoring flange 403 also ensures maximum surface contact with the back seat armrest mounting bracket interface, thereby eliminating additional washers for surface contact.

In addition, the addition of the non-anchoring flange region to the mounting shaft provides uniform stress distribution throughout the shaft and allows stress lines to be directed to flow smoothly and evenly away from the usual stress concentration areas on the mounting shaft.

Thus, due to the design of the proposed shock absorber mounting shaft, the stress streamlines are spread evenly to the outside of the mounting shaft and away from the center.

While the present subject matter has been described with reference to specific embodiments, this description is not intended to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternative embodiments of the subject matter, will become apparent to persons skilled in the art upon reference to the description of the subject matter. It is therefore contemplated that such modifications may be made without departing from the spirit or scope of the present subject matter as defined.

Claims

1. A frame assembly (102) for a two-or three-wheeled vehicle (100), the frame assembly (102) comprising:

a pair of rear frames (202) extending rearward from the main frame (201);

a pair of side frames (203) extending downward from at least a portion of the pair of rear frames (202);

a reinforcement member (204) disposed adjacent to at least a portion of the pair of rear frames (202), wherein the reinforcement member (204) is configured to connect the pair of rear frames (202) and the pair of side frames (203); and

a shock absorber mounting shaft (205) attached to at least a portion of the reinforcement member (204), the shock absorber mounting shaft (205) comprising varying transverse sections a1, a2, B, and C in that order, wherein the transverse section a2 is an un-anchored flange;

wherein the shock absorber mounting shaft (205) comprises a blind hole (403), the blind hole (403) depending on K: l and K': the ratio of L ' is configured, where K is the length of the shock absorber mounting shaft (205) between welds, and L is the depth of the blind hole (403), and K ' is the diameter of the section A1 of the shock absorber mounting shaft (205), and L ' is the diameter of the blind hole (403).

2. The frame assembly (102) for a two-or three-wheeled vehicle (100) according to claim 1, wherein the section a1 is welded on both sides to at least one reinforcement member (204), the section B houses at least a portion of a shock absorber (117), and the section C has a threaded profile configured to receive one or more mounting members (117B).

3. The frame assembly (102) for a two-or three-wheeled vehicle (100) according to claim 1, wherein said shock absorber mounting shaft (205) is configured to receive an eye (117 a) of at least one shock absorber (117).

4. The frame assembly (102) for a two-or three-wheeled vehicle (100) according to claim 3, wherein the shock absorber mounting shaft (205) is configured to receive at least a portion of a rear seat armrest mount (106 a) of a rear seat armrest (106).

5. The frame assembly (102) for a two-or three-wheeled vehicle (100) according to claim 4, wherein the eyelet (117 a) and the rear seat armrest mount (106 a) are attached to the shock absorber mounting shaft (205) by one or more mounting members (117 b).

6. The frame assembly (102) for a two-or three-wheeled vehicle (100) according to claim 1, wherein said varying transverse sections a1, B and C are configured with a different decreasing diameter compared to the diameter of said non-anchored flange (a 2).

7. The frame assembly (102) for a two-or three-wheeled vehicle (100) according to claim 1, wherein the ratio K: L is 2: 1.

8. The frame assembly (102) for a two-or three-wheeled vehicle (100) according to claim 1, wherein the depth of the blind hole (403) is 1/2 of the length (K) of the shock absorber mounting axle (205) between weld seams, and the diameter (L ') of the blind hole is 1/2 of the diameter (K') of the section A1 of the shock absorber mounting axle.

9. A shock absorber mounting shaft (205) configured to receive at least one shock absorber (117) of a two-or three-wheeled vehicle (100), the shock absorber mounting shaft (205) comprising:

varying transverse sections A1, A2, B, and C, the section A1 welded on both sides to at least one reinforcement member (204), the section A2 being a non-anchoring flange, the section B housing at least a portion of the shock absorber (117), and the section C having a threaded profile configured to receive one or more mounting members (117B), the non-anchoring flange A2 disposed at a middle portion of the shock absorber mounting shaft (205);