Technical Field

[0001] The present subject matter as described herein generally relates to a front fork assembly for a motorcycle and particularly relates to an integrated dust bellow of said front fork assembly.

Background

[0002] Suspension systems are provided in vehicles including motorcycles to isolate body of a vehicle from bumps and vibrations, while keeping wheels in contact with the road. Typically, a front wheel suspension system of a motorcycle includes a telescopic front fork "assembly. Said telescopic front fork assembly includes two" parallel telescopic suspension members or front forks. Each of said front forks includes an outer-stationary tube connected to an axle of a front wheel of the motorcycle, an inner slider tube capable of reciprocatory motion with respect to said outer stationary tube, and a dust seal disposed in a junction formed between said inner slider tube and the outer stationary . tube.

[0003] Dust and mud entry is one of the major causes for decline in performance of the suspension systems. Typically, in a motorcycle, a front fender disposed, above the front wheel prevents mud entry towards the inner slider tube. However, disposition of the front fender alone does not serve to prevent mud from entering either into the inner slider tube or the outer stationary tube through the dust seal. Chances of dust and mud entry into the front forks through gaps in the dust seal are still high, resulting in damage to the front forks. Conventionally, a dust bellow is provided to prevent dust from entering the dust seal.

[0004] Conventionally, while the dust seal is disposed in thejunction formed.between said inner slider tube and outer stationary tube, the dust bellow is concentrically disposed around the inner slider tube to cover the dust seal at least partially. Further, in order to prevent the dust bellow from sliding away from the dust seal, in a known art, said dust bellow is clamped to the inner slider tube using clamping rings at an upper end and a lower end of said inner slider tube. Thus, use of both the.dust bellow in the front fork assembly not only involves the use of additional parts such as clamps, it also involves additional assembly steps, thereby, leading to an increase in assembly time and therefore affecting productivity. Moreover, the cost involved is also high.

[0005] In another known art, the dust bellow is seated on a groove
formed on the outer stationary tube. However, seating of the dust bellow on the groove is often affected due to manufacturing variations in the formation of the groove. As a result, the chances of dust bellow slipping away from the dust seal are high, leading to dust and mud entry into the dust seal."

[0006] There is therefore a need to prevent slippage of said dust bellow away from said dust seal without involving the use.of additional parts.

Summary of the Invention

[0007] The present invention has been made in view of the above circumstances.

[0008] It is an object of the present invention to provide a front fork "assembly for a motorcycle, said front fork assembly adapted to effectively prevent dust from entering therein.

[0009] It is another object of the present invention to reduce the total number of components used in the front fork assembly and at the same time reliably ensure that dust is prevented from entering into said front fork assembly.

[0010] " It is yet another object of the present invention to reduce time involved in assembling the components of the front fork assembly and thereby improve overall productivity of manufacturing.

[0011] It is still another object of the present invention to ensure that the front fork assembly including its constituent members have a long and effective service life.
[0012] Accordingly, the present invention relates to a front fork assembly for a motorcycle. In accordance with the present invention, the front fork assembly includes an integrated dust bellow adapted to prevent dust from entering said front fork assembly. The integrated dust bellow includes a bottom dust seal portion, an intermediate bellow portion and a ■ top holding portion.

[0013] As per an embodiment of the present invention, the integrated dust bellow including the bottom dust seal portion, the intermediate bellow portion and the top holding portion constitutes a single unit made by injection moulding. The integrated dust bellow in the present embodiment is made of an elastic material having sufficient rigidity.

[0014] The integrated dust bellow has a cylindrical construction. Further, as per an aspect of the present invention, the integrated dust bellow is formed in a manner such that the bottom dust seal portion has a shape complimentary to that of an upper portion of said outer stationary tube, and is adapted to be seated, at least partially around an outer circumference of the upper portion of said outer stationary tube. Further, the top holding portion having an inner diameter smaller than that of the,
intermediate bellow portion is held against an upper portion of the inner slider tube. Furthermore, the intermediate bellow portion accommodates the inner slider tube. As per another embodiment of present invention, the integrated dust bellow may extend from the inner slider tube upto and including a junction formed between said inner slider tube and said outer stationary tube, and is adapted to securely cover, said junction.

[0015] As per an aspect of the present invention, said integrated dust bellow having a construction as described above is slid over the inner slider tube in a manner so that it covers an outer circumference of the ■ inner slider tube, and at least partially covers an outer circumference of the outer stationary tube, and allows reciprocatory motion of said inner slider tube with respect to said outer stationary tube. Thus, since the integrated dust bellow extends from the inner slider tube up to the upper portion of the outer stationary tube, at least a portion of the integrated dust bellow also seals a junction formed between the inner slider tube and the outer stationary tube.

[0016] Particularly, while the bottom dust seal portion and the top holding portion aid in tightly holding the integrated dust bellow against the . upper portion of the inner slider tube and the outer stationary tube respectively, the intermediate bellow portion accommodates .the inner slider tube. Thus, since'the bottom dust seal portion is tightly held against the junction formed between the inner slider tube and outer stationary tube, dust is prevented from entering into the front fork assembly. Moreover, since the bottom dust seal portion is formed integrally along with the intermediate bellow portion, separate clamp need not be provided to prevent sliding of .the intermediate bellow portion away from the bottom dust seal portion, as in the case of conventional front fork assemblies. Consequently, the assembly time involved is less.

[0017] Summary provided above explains the basic features of the
invention and does not limit the scope of the invention. The nature and further characteristic features of the present invention will be made clearer from the following descriptions made with reference to" the accompanying drawings.

Brief Description of Drawings

[0018] The above and other features, aspects, and advantages of the subject matter will be better understood with regard to the following description and accompanying drawings where:

[0019] FIG. 1 illustrates a side view of a motorcycle in accordance, with the present invention.
[0020] FIG. 2 illustrates a side view of a front fork assembly comprising an integrated dust bellow in accordance with an embodiment of the present invention.

[0021] FIG. 3 illustrates an exploded view of the front fork assembly in accordance with an embodiment of the present invention.

[0022] FIG. 4 illustrates a cross sectional view of the integrated dust bellow in accordance with a first embodiment of the present invention.

[0023] FIG.5 illustrates a cross sectional view of the integrated dust bellow in accordance with a second embodiment of the present invention.

[0024] FIG.6a illustrates a first aspect for mounting of the integrated dust bellow illustrated in FIG.5.
[0025] FIG.6b illustrates a perspective view of the front fork assembly comprising the integrated dust bellow as shown in FIG.6a.

[0026] FIG.7a illustrates a second aspect for mounting of the integrated dust bellow illustrated in FIG.5.

■ [0027] FIG.7b illustrates a perspective view of the front fork assembly comprising the integrated dust bellow as shown in FIG. 7a..

[0028]. FIG. 8a illustrates a third aspect for mounting of the integrated dust bellow illustrated in FIG.5.

[0029] FIG. 8b illustrates a perspective view of the front fork assembly comprising the integrated dust bellow as shown in FIG. 8a.
[0030] FIG.8c illustrates a cross sectional view of the integrated dust bellow depicted in FIG. 8a. Detailed Description of the Preferred Embodiments

[0031] The front fork assembly including the integrated dust bellow is explained in greater detail in conjunction with the figures in the following description. Various other features and embodiments of the present invention will be discernible from the following further description thereof, set out hereunder.. The brief description is to be understood as an exemplary embodiment and reading of the invention is not intended to be taken restrictively. Also, it is to be noted that although the embodiments of the present invention have been exemplified for a motorcycle, the present invention may be used in any other two wheeled vehicle including a scooter. It is to be further noted that "front" and "rear", and "left" and "right" wherever referred to in the ensuing description, refer to front and rear, and left and right directions as seen in a state of being seated on a seat of the motorcycle and looking forward. Furthermore, a longitudinal axis unless otherwise mentioned refers to a front to rear, axis relative to'the . motorcycle, while a lateral axis unless otherwise mentioned refers generally to a side to side, or left to right axis relative to the motorcycle.

[0032] FIG. 1 illustrates a side view of a motorcycle 10 in accordance with the present invention. The motorcycle 10 includes a body frame 13 to support different parts of said motorcycle 10. A head pipe 14 is provided at a front end of the body frame 13. The head pipe 14 supports a steering shaft (not shown) rotatably in a certain range. In an upper portion of the head pipe 14, a handlebar 16 is rotatably integrally connected to the steering shaft. The handlebar 16 is used to steer the motorcycle 10 and is connected to a front wheel 17 through the steering shaft. An upper portion of the front wheel 17 is covered by a front fender 18 which prevents mud from getting deflected towards the steering shaft. Further, a front fork assembly 40 is supported on the front fender 18 . through a brace bracket (not shown).

[0033] In a front portion of the body frame 13 a fuel tank 19 is arranged immediately behind the handle bar 16 and is disposed over an engine 12. A seat 20 is placed behind the fuel tank 19. The seat 20 includes a front rider portion and rear pillion portion.

[0034] For the safety of the rider and in conformance with the traffic rules, a headlight 31 in the front portion of the motorcycle and a taillight 32 in the rear portion of the motorcycle 10 is also included.

[0035] Suspension systems are provided for comfortable steering of the motorcycle on the road. The front fork assembly 40, which forms the front suspension system, serves as rigidity component just like the body frame. The front fork assembly 40 clamped to the head pipe 14 through an upper bracket 14a and a lower bracket 14b is capable of being moved to the left and right. Further, a rear suspension system, which is a hydraulic damped arrangement, is connected to the body frame 13. The rear suspension system comprises of at least one rear suspension 45 preferably on a left hand side of the motorcycle 10. However, in a motorcycle with two rear suspensions, the same may be disposed on the left side and the right side respectively of said motorcycle.

[0036] The engine 12 is supported to the body frame 13 by being suspended in a front lower portion of the body frame 13. The,engine 12 is equipped with an exhaust system that includes an exhaust pipe (not shown) connected to the engine 12 and a muffler (not shown) connected to the exhaust pipe. The muffler (not shown) extends rearwards along the right side of the rear wheel 30.

[0037] Further, a swing arm 35 extending rearwards is swingably connected to a rear lower portion of the body frame 13. The rear wheel 30 - is rotatably supported at a rear end of the swing arm 35. Power from the engine 12, suspended in a front lower portion of the body frame 13 is transmitted to the rear wheel 30 through a power drive mechanism, such as a drive chain, so as to drive and rotate the rear wheel 30.

[0038] A rear fender 55 for covering an upper side of the rear wheel 30 is mounted to a rear portion of body frame 13. Most of the rear portion of the body frame 13 is covered with a rear cowl 60.

[0039]' Referring to FIG. 2 and FIG.3 a description of the front fork
assembly 40 is given. Said front fork assembly 40 is connected at its upper end to the head pipe 14 through the upper bracket 14a and at its lower end to a the lower bracket 14b, and to the front wheel 17 through its axle 17a. The front fork assembly 40 thus connected to the head pipe 14 and the front wheel 17, comprises an outer stationary tube 40a connected to the axle 17a of the front wheel 17, an inner slider tube 40b operatively connected to the outer stationary tube 40a, and an integrated dust bellow 40c concentriacally disposed around said inner slider tube 40b, and extending upto and including an upper portion of said outer stationary tube 40a. Further, the front fork assembly 40 also comprises compression springs (not shown) and an oil seal (not shown). To ensure efficient damping performance of the front fork assembly 40, oil is filled in the outer stationary tube 40a. To prevent leakage of the oil to the outside, the oil seal is disposed within a junction 40d formed between the outer stationary tube 40a and the inner slider tube 40b. The oil seal disposed within said junction 40d is susceptible to damage due to dust and mud entry through gaps in said junction 40d. In another embodiment, a dust seal may also be disposed at the junction and above the oil seal to prevent damage to said oil seal.

[0040] Damage to the oil seal and said dust seal is prevented by the integrated dust bellow 40c disposed on the inner slider tube 40b, the construction of which is explained with reference to FIG.4 -FIG-8.

[0041] FIG.4 illustrates a cross section of the integrated dust bellow 40c as per a first embodiment of the present invention. The integrated dust bellow 40c has a cylindrical construction and includes a bottom dust seal portion 40ca, an intermediate bellow portion 40cb, and a top holding portion 40cc.

[0042] As per the present invention, the integrated dust bellow 40cincluding the bottom dust seal portion 40ca, the intermediate bellow portion 40cb, and the top holding portion 40cc is formed as a single integrated unit by injection moulding. Preferably, an elastic material such as rubber is used to-form the integrated dust bellow 40c. The cross section A-A of the integrated dust bellow 40c shows that the bottom dust seal portion 40ca is formed with a first inner rib 40cai and a second inner rib 40cao. Further, the intermediate bellow portion 40cb is'formed in a manner such that pluralities of folds 40cba are formed therein. Preferably, an angle formed between adjacent folds of said pluralities of folds is maintained at less than 60°. The top holding portion 40cc is also formed with a holding rib 40ch. While the bottom dust seal portion 40ca is press fitted onto the junction 40d formed between the inner slider tube 40b and the outer stationary tube 40a, the top holding portion 40c is held against an upper portion of the inner slider tube 40b. The integrated dust bellow 40c thus formed is concentrically disposed around the inner slider tube 40a.

[0043] As per an aspect of the first embodiment, the integrated dust bellow 40c is slid over the inner slider tube 40b. The integrated dust bellow 40c thus disposed on the inner tube 40b extends from an upper portion thereof up to the junction 40d formed between the outer stationary tube 40a and said inner slider tube 40b.

[0044] When said integrated dust bellow 40c is thus disposed around the inner slider tube 40b, the bottom dust seal portion 40ca tightly encloses the junction 40d formed between the inner slider tube 40b and the outer stationary tube 40a. The first inner rib 40cai and the second inner rib 40cao cooperate with ribs correspondingly formed in the junction 40d to tightly seal the junction 40d so as not to leave any gap therebetween. Thus, the bottom dust seal portion 40ca tightly encloses the junction 40d. Further, the top holding portion 40cc aids in holding the integrated dust bellow 40c against an upper portion of the inner slider tube 40b. Thus, the integrated dust bellow 40c is tightly held against the inner slider tube 40b. However, while the integrated dust bellow 40c is tightly held against the inner slider tube 40b, it is also imperative to ensure that the reciprocatory motion of the inner slider tube 40b with respect to the outer stationary tube 40a is not restricted. A bellow construction of said intermediate bellow portion 40cb ensures free unrestricted sliding motion/ reciprocatory motion of the inner slider tube 40b. Thus, the intermediate bellow portion 40cb accommodates the inner slider tube 40b.

[0045] FIG.5 illustrates a cross section B-B of the integrated dust bellow 40c as per a second embodiment of the present invention. A length of the bottom dust seal portion 40ca illustrated in FIG.4 is extended so that said bottom dust seal portion includes an extended portion 40cab. In other words, a base 40cac of said bottom dust seal portion 40ca is extended downwards towards the outer stationary tube 40a so that when the bottom dust seal portion 40ca is press fitted on to the junction 40d, the extended portion 40cab covers the outer stationary tube 40a at least partially at its upper portion thereof. Thus, the overall length of the integrated dust bellow 40c is increased. Extending length of said integrated dust bellow 40c at a bottom portion thereof aids in increasing an overall coverage area of said integrated dust bellow 40c and therefore aids in effectively preventing dust or mud from entering into the front fork assembly 40. Also, the extended portion 40cab serves as an attachment portion of said integrated dust seal bellow 40c.

[0046] For example, as illustrated in FIG.6a an integral mounting lug 42 is provided on the extended portion 40cab of the integrated dust bellow 40c so that said integrated dust bellow 40c can be supported on a brace fender 43 having a mounting hole 43a. Additionally, as illustrated in FIG. 6b, fasteners are used to fasten said brace fender 43 to the integrated dust bellow 40c at the extended portion 40cab thereof. Particularly, said fasteners are fastened through a pair of projections 40ap provided on said outer stationary tube 40b. A cut out 40ce is provided in said extended portion 40cab to accommodate said pair of projections 40ap. Further, a clamp 44 may be used to clamp the top holding portion 40cc to the inner slider tube 40b. Thus, the integrated dust bellow 40c is reliably secured to the inner slider tube 40a. Providing said clamp 44 is optional for greater reliability in securing said integrated dust bellow 40c to the inner slider tube 40b.

[0047] Alternatively, as illustrated in FIG.7a and FIG.7b, the integrated dust bellow 40c is secured to the brace fender 43 through a holding bracket 46 fastened to said brace fender 43. Arms of the holding bracket 46 clamp the integrated dust bellow 40c to the inner slider tube 40b. Further, said arms of the holding bracket 46 are held against a slot 50 (shown in FIG.8c) formed between the extended portion 40cab and the bottom dust seal portion 40ca.

[0048] In another embodiment as illustrated in FIG.8a, 8b and FIG.8c, the integrated dust bellow 40c is secured to the brace fender 43 through a left and right mounting bracket 47. The brace fender 43 is supported on said dust bellow 40c through the left and right mounting bracket 47 by means of fasteners. The left and right mounting bracket 47 is held in the slot 50 provided in the bottom dust seal portion 40ca.

[0049] In another aspect of the second embodiment, the cut out 40ce is provided on the extended portion 40cab to accommodate the pair of projections 40ap disposed on the outer stationary tube 40a for mounting said outer stationary tube 40a to the brace fender 43.

[0050] Thus, the integrated dust bellow 40c is primarily adapted to be directly press fitted onto the junction 40d as per the first embodiment of the invention, so that the integrated dust bellow 40c is tightly secured to the inner slider tube 40b and tightly enclosing said junction 40d, thereby preventing slipping of said dust bellow away from said junction. The . second embodiment of the present invention can be specifically adopted in motorcycles having the brace fender 43, so that presence of the brace fender 43 can be effectively used to ensure that integrated dust bellow 40c is tightly held onto the inner slider tube 40b, and is prevented from moving away from the junction 40d.

[0051] Thus, the integrated dust bellow 40c concentrically disposed around the inner slider tube 40b ensures that dust and mud are effectively prevented from entering into the front fork assembly 40, thereby aiding in increasing the service life of the front fork assembly. Additionally, the integrated dust bellow 40c also adds to the aesthetic appeal of the motorcycle as it highlights the strokes of the inner slider tube over the outer stationary tube.

[0052] While the present invention has been shown and described with reference to the foregoing preferred embodiments, it will be apparent to those skilled in the art that changes in form, connection, and detail may be made therein without departing from the spirit and scope of the invention as defined in the appended ■ claims.

I/We Claim:

1. A front fork assembly (40) for a motorcycle. (10), wherein said front fork assembly (40) comprises: an outer stationary tube (40a) adapted to be connected to an axle (17a) of a front wheel (17) of said motorcycle (10), and an inner slider tube (40b) capable of performing reciprocating motion with respect to the outer stationary tube (40b), and connected to a head tube (14) of said motorcycle (10), characterized in that, said front fork assembly (40) further comprises an integrated dust bellow (40c) adapted to be concentrically disposed around said inner slider tube (40b), in a manner so as to at least partially cover at least said inner slider tube (40b) and at least said junction (40d) formed between said inner slider tube (40b) and said outer stationary tube (40a), wherein said integrated dust bellow (40c) is a cylindrical member comprising a bottom dust seal portion (40ca), an intermediate bellow portion (40cb), and a top holding portion (40cc).

2.- The front fork assembly (40) as claimed in claim 1, wherein the bottom dust seal portion (40ca) includes a first inner rib (40cai), and a second inner rib (40cao) for mating with corresponding ribs
provided in said junction (40d).

3. The front fork assembly (40) as claimed in claim 1 or claim 2, wherein the bottom dust seal portion (40ca) further includes an extended portion (40cab) adapted to annularly cover at least an upper portion of the outer stationary tube (40a).

4. The front fork assembly (40) as claimed in claim 3, wherein said extended portion (4Qcab) includes at least an integral mounting lug (42) for mounting to a brace fender (43) of said motorcycle (10).

5. The front fork assembly (40) as claimed in claim 1 or claim 4, wherein said bottom dust seal portion (40ca) includes a slot (50) adapted to receive a portion of a holding bracket (46) fastened to said brace fender (43).

6. The front fork assembly (40) as claimed in claim 3 or claim 5, wherein said extended portion (40cab) includes a cut out (40ce) to accommodate a pair of projections (40ap) provided on the outer stationary tube (40a), for fastening- with a portion of said brace fender (43).

7. The front fork assembly (40) as claimed in claim T, wherein the integrated dust bellow (40c) is made of an elastic material.

8. The front fork assembly (40) as claimed in claim 1, wherein the junction (40d) includes a dust seal.

9. A motorcycle (10) including the front fork assembly (40) as claimed in claims 1-8.