DESC:TECHNICAL FIELD
[0001] The present subject matter relates generally to a two-wheeled vehicle. More particularly but not exclusively, the present invention relates to a frame structure for a motorcycle.
BACKGROUND
[0002] In conventional frames for a motorcycle with mono shock absorber, the shock absorber is directly connected to the main frame of the motorcycle. One end of the shock absorber is connected to a bracket extending rearwardly from an upper portion of the main frame, and a swing arm supports its lower end. Since the mono shock absorber is directly connected to the main frame at one end, the main frame should possess sufficient strength to take the load from the mono shock absorber. However, in conventional frames for a motorcycle with mono shock absorber, the rear frame structure is usually bolted to the main frame and this does not provide the main frame the desired strength to take load from the mono shock absorber.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] The detailed description is described with reference to the accompanying figures. The same numbers are used throughout the drawings to reference like features and components.
[0004] Figure 1 illustrates a side view of a typical motorcycle.
[0005] Figure 2 particularly illustrates a side view of the body frame structure of the motorcycle in accordance to the present invention.
[0006] Figure 3 illustrates a detailed view of a substantially front portion of a pair of right and left upper tubes.
[0007] Figure 4 illustrates a sectional view of the first bridge member of the at least one bridge member.

DETAILED DESCRIPTION
[0008] A pair of right and left upper tubes is welded to the main frame. The stress exerted on the main frame affects the adjoining pair of right and left upper tubes. In order to provide better structural stability to the pair of right and left upper tubes, in the rear portion of such frames, a bridge bracket is connected to the two upper tubes on the left and right sides of the motorcycle. Further, two side tubes are flattened at one end and are welded to the upper tubes. Also, in addition to welding the side tubes to the upper tubes, stiffener plates are also welded between the upper tubes and the side tubes on both the left and right sides of the motorcycle to provide more strength to the frame. However, the welding of the stiffener plates between the two tubes increases the number of parts, the weld length and weight of the frame. In addition, it takes additional time to manufacture the frame thereby causing loss of productivity.
[0009] Further, in a conventional frame structure, the pair of right and left upper tubes is supported at only two portions, including, one welded joint to the main frame and other welded joint of the pair of right and left upper tubes with the pair of right and left side tubes. The portion of the pair of right and left upper tubes between the one welded joint and the other welded joint lacks sufficient support. This may cause the pair of right and left upper tubes to undergo deformation. Further, due to lack of sufficient support, it is not possible to maintain required uniform gap between the pair of right and left upper tubes. The uniform gap maintained between the pair of right and left upper tubes is used to access an air filter assembly that is disposed there under. Hence, the conventional construction of the pair of right and left upper tubes does not facilitate easy accessibility to the air filter assembly.
[00010] Furthermore, the lack of uniform gap between the pair of right and left upper tubes does not enable easier access to the mono shock absorber. Due to which, a tool member used to adjust one of the several features of the mono shock absorber cannot be accommodated.
[00011] The above mentioned problem can be overcome by providing sufficient strength to the main frame for a motorcycle with a mono shock absorber without involving the use of additional stiffener plates between the two upper tubes and side tubes, thereby reducing the number of parts. In order to achieve the above-mentioned object, at least one bridge member is placed between the two upper tubes along the vehicle lateral axis and it is extended downwardly from the upper tubes to the side tubes. The at least one bridge member facilitates to maintain desired uniform gap between the pair of right and left upper tubes. The uniform gap so achieved facilitates easier access to the air filter assembly and also facilitates easier adjustment of the mono shock absorber.
[00012] The at least one bridge member is welded to the pair of right and left upper tubes. The welded portion on the pair of right and left upper tubes ruptures or damages the surrounding parts. For example, the welded portion of the pair of right and left upper tubes supports at least a portion of one or more cushion members of the seat assembly. Therefore, the welded portion near the surrounding parts on the pair of right and left upper tubes is not desired.
[00013] The above discussed problems with respect to the frame assembly can be overcome according to the proposed invention and is as discussed below.
[00014] According to an embodiment of the present invention, the at least one bridge member is fixedly attached, more specifically, is welded to the pair of right and left upper tubes. In order to prevent the rupturing or damaging of the parts disposed near the welded portion, the welding is carried out at a portion away from the surrounding parts. For example, in the present embodiment, a portion of the at least one bridge member is capable of receiving at least a portion of one or more cushion members of a seat assembly. The cushion members are substantially supported on the at least one bridge member. The proper placement of the cushion members provides required support to the seat assembly.
[00015] According to an embodiment of the present invention, in order to provide sufficient structural support to the pair of right and left upper tubes, the at least one bridge member is extended downwardly from the pair of right and left upper tubes. The downward extension of the at least one bridge member provides maximum contact surface between the at least one bridge member and the pair of right and left upper tubes. The sufficient contact surface provides required stability to the welded portion between the at least one bridge member and the pair of right and left upper tubes. Furthermore, required substantial structural support is provided to the pair of right and left upper tubes.
[00016] The bridge member is welded to the upper tubes and the side tubes on either side, thereby, eliminating the need for additional stiffener plates to be placed between the upper tubes and the side tubes. This improves the rigidity of the frame, while reducing assembly and material cost.
[00017] An embodiment of body frame for a motorcycle with reference to the accompanying drawings will be described hereunder in accordance to the present invention. Various features of the body frame in accordance to the present invention will become discernible from the following description set out hereunder. It is further to be noted that terms “upper”, “lower”, “right”, “left”, “rearward”, “forward”, “downward” and like terms are used herein based on the illustrated state or in a standing state of a motorcycle with a driver riding thereon. Furthermore, a longitudinal axis refers to a front to rear axis relative to the vehicle, while a lateral axis refers to a side to side, or left to right axis relative to the vehicle.
[00018] Figure 1 illustrates a left side view of a motorcycle 100. The motorcycle 100 includes a frame structure 109, a front fork 107 mounted to the front of the frame structure 109 and connected to a front wheel 108, an engine assembly 110 supported by the frame structure 109 and a rear wheel 112 supported by the rear portion of the frame structure 109.
[00019] In the illustrated motorcycle 100, a head pipe 105 supports a steering shaft (not shown) rotatably in a certain range. The front fork 107 is supported pivotally by the head pipe 105. In an upper portion of the head pipe 105, a handlebar assembly 101 is rotatably integrally connected to the steering shaft. A front wheel 108 is journaled to a lower end of the front fork 107 and the front wheel 108 is rotated in a certain range by steering the handlebar assembly 101.
[00020] A front fender 106 is arranged on the front fork 107 to cover an upper portion of the front wheel 108. A rear wheel 112 is journaled on the rear end of the frame structure 109.
[00021] In a front portion of the frame structure 109 a fuel tank 102 is arranged immediately behind the handle bar 101. A seating seat 103,104 is placed behind the fuel tank 102. The seating seat 103,104 includes a front seat 103 and a rear seat 104. The front seat 103 is placed immediately behind the fuel tank 102, while the rear seat 104 is disposed in an upper position behind the front seat 103.
[00022] An engine assembly 110 is supported to the frame structure 109 by being suspended in a front lower portion of the frame structure 109. The engine assembly 110 is equipped with an exhaust system and includes an exhaust pipe (not shown) connected to the engine and a muffler (not shown) connected to the exhaust pipe. The muffler extends rearwards along the right side of the rear wheel 112.
[00023] Furthermore, a swing arm (not shown) is swingably connected to a rear lower portion of the frame structure 109 and the swing arm extends rearwards. The rear wheel 112 is rotatably supported at a rear end of the swing arm. A mono shock 113 is supported by the swing arm at one end. Power from engine assembly 110 suspended in a front lower portion of the frame structure 109 is transmitted to the rear wheel 112 through a power drive mechanism, such as a drive chain, so as to drive and rotate the rear wheel 112.
[00024] Figure 2 particularly illustrates the frame structure of the motorcycle 100. The frame structure 109 includes a head pipe 105, a main tube 201 extending rearwards from an upper portion of the head pipe 105, a pair of right and left front tubes 203 extending downwards from the lower portion of the head pipe 105, a downtube 206 extending downwards from the lower portion of the main tube 201, a pair of right and left upper tubes 203 extending obliquely upward in a rearward direction from a connecting portion 201a of the main tube 201, a pair of right and left side tubes 207 extending forwardly and downwardly from the pair of right and left upper tubes 203 and connected to the down tube 206.
[00025] At least one bridge member 202, 208, 209 are placed between the pair of right and left upper tubes 203 along a vehicle lateral axis pq. Further, the at least one bridge member 202, 208, 209 extends downwardly from the pair of right and left upper tubes 203. Welding the at least one bridge member 202, 208, 209 to the pair of right and left upper tubes 203 adds strength to the rear portion of frame structure 109 and eliminates the need for additional stiffeners.
[00026] The at least one bridge members 202, 208, 209 not only acts as a reinforcing member for the body frame but also performs the function of a mounting member for a seat lock, certain electrical components and other components of the vehicle.
[00027] From the above description, it is noted that the present invention has the following advantages:
i. Welding the at least one bridge members to the pair of right and left upper tubes in accordance to the present invention improves the torsional stiffness of the rear portion of the body frame and thereby provides rigidity to the body frame.
ii. As the rigidity of the frame increases due to welding of the at least one bridge members to the pair of right and left upper, the need for additional stiffeners between the upper tubes is eliminated. This not only reduces the weight of the body frame but also reduces the cost of manufacturing of the frame.
iii. The at least one bridge members in accordance to the present invention can be used to mount a seat lock, electrical components and other components.
[00028] Further, a first bridge member 202 is placed at a substantially front portion between the pair of right and left upper tubes 203 and the second bridge member 208 is placed at a substantially rear portion of the pair of right and left upper tubes 203, between the pair of right and left upper tubes 203 along the vehicle lateral axis. Further, the first bridge member 202 extends downwardly from the pair of right and left upper tubes 203. The third bridge member 209 is disposed at a rear end of the motorcycle 100. According to an embodiment, all of the bridge members including the first bridge member 202, second bridge member 208 and the third bridge member 209 extend downwardly from the pair of right and left upper tubes 203.
[00029] Fig. 3 illustrates a detailed view of a substantially front portion of a pair of right and left upper tubes. The at least one bridge member 202, 208, 209 is disposed in between the pair of right and left upper tubes 203. The at least one bridge member 202, 208, 209 is disposed at a substantially front portion of the pair of right and left upper tubes 203.
[00030] Fig. 4 illustrates a sectional view of the first bridge member of the at least one bridge member. The first bridge member 202 of the at least one bridge member 202, 208, 209 is disposed in between the right and left upper tubes 203. The vehicle transverse axis pq passes through the centre of the pair of right and left upper tubes 203. Further, a perpendicular axis xy also passes through the centre of the pair of right and left upper tubes 203, but perpendicular to the transverse axis pq. Further, the at least one bridge member 202, 208, 209 includes at least one lateral end 202a, 202b. Each of the at least one lateral end 202a, 202b overlaps with the pair of right and left upper tubes 203. The each of the at least one lateral end 202a, 202b extends beyond the perpendicular axis xy. Furthermore, each of the at least one lateral end 202a, 202b includes a smooth curved surface ra, rb. In particular, the smooth curved surface ra, rb is overlapping with each of the lateral end 202a, 202b. The overlapping of the smooth curved surface ra, rb with each of the lateral end 202a, 202b provides better contact area and improved stability to the frame structure 109.
[00031] Although the subject matter has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible. It is to be understood that the aspects of the embodiments are not necessarily limited to the features described herein.
,CLAIMS:WE CLAIM:
1. A frame structure (109) for a motorcycle (100), said frame structure (109) comprising:
a head pipe (105);
a main tube (201) extending rearwards from an upper portion of the head pipe (105);
a downtube (206) extending downwards from a connecting portion (201a) of the main tube (201);
a pair of right and left front tubes (205) extending downwards from a lower portion of the head pipe (105);
a pair of right and left upper tubes (203) extending rearwards and upwards from the main tube (201);
a pair of right and left side tubes (207) extending forwardly and downward from the rear portion of the pair of right and left upper tubes (203); and
at least one bridge member (202, 208, 209),
wherein, the at least one bridge member (202 208, 209) is secured along a vehicle lateral axis (pq) between the pair of right and left upper tubes (203), said at least one bridge member (202 208, 209) includes at least one lateral end (202a, 202b) disposed overlappingly above said pair of right and left upper tubes (203) and said each of the at least one lateral end (202a, 202b) extends beyond a perpendicular axis (xy).
2. The frame structure (109) for a motorcycle (100) as claimed in claim 1, wherein said at least one bridge member (202, 208, 209) includes a first bridge member (202) disposed at a substantially front portion between the pair of right and left upper tubes (203).
3. The frame structure (109) for a motorcycle (100) as claimed in claim 1, wherein said at least one bridge member (202, 208, 209) includes a second bridge member (208) disposed at a substantially rear portion between the pair of right and left upper tubes (203).
4. The frame structure (109) for a motorcycle (100) as claimed in claim 1, wherein said at least one bridge member (202, 208, 209) includes a third bridge member (209) disposed at a rearmost end between the pair of right and left upper tubes (203).
5. The frame structure (109) for a motorcycle (100) as claimed in claim 1, wherein said at least one bridge member (202, 208, 209) is connected to the pair of right and left upper tubes (203).
6. The frame structure (109) for a motorcycle (100) as claimed in claim 2, wherein said at least one bridge member (202, 208, 209) is connected to the pair of right and left upper tubes (203) by means of a forging process.
7. The frame structure (109) for a motorcycle (100) as claimed in claim 1, wherein said at least one bridge member (202, 208, 209) is capable of supporting components on the frame structure (109), said components include a seat assembly, a seat lock and an ECU unit.
8. The frame structure (109) for a motorcycle (100) as claimed in claim 1, wherein said frame structure (109) is either a fixed frame or a split frame.
9. The frame structure (109) for a motorcycle (100) as claimed in claim 1, wherein said at least one bridge member (202, 208, 209) is made of known metals.
10. A motorcycle (100) comprising the frame structure (109) as claimed in any of the preceding claims.

Dated this 16TH Day of January 2017

S. Ramiah
General Manager – R&D
TVS Motor Company Limited