DESC:LIGHT WEIGHTING FRONT FORK SYSTEM FOR VEHICLE

Field of invention:

The present invention relates to a front suspension system of automobiles and more particularly, materials used for constructing light weight front forks.

Background of the invention:

The typical motorcycle has a pair of fork tubes for the front suspension, which provides proper damping through traction with the road surface. Telescopic Front fork consists of three to four major parts which contributes to overall weight of the Limb i.e., Aluminium Outer tube, Steel Inner tube, Coil Spring and Oil. Every part has an importance and limitations to change the specifications on their properties like wall thickness, physical characteristics. Any change on material and physical parameters of these parts will affect product performance and safety.

The challenge is the final part should not lower its characteristics when compared to the original part characteristics and also have a light weight. This is one of the major draw-back of conventional front fork designs, which fail to provide light weight front fork. There is a need to attempt on alternate material with hybrid methods to achieve the light weighting challenge.

Accordingly, there is a need of lightweight materials like reinforced steel sheets and special plastics for constructing light weight front forks that overcomes the above mentioned drawbacks of the prior art.

Object of the invention:

An object of the present invention is to provide front forks with a combination of higher strength and lighter weight, also with an added advantage of reducing carbon foot print.

Another object of the present invention is to eliminate the long and tedious supply chain activity of process in constructing front forks starting from casting, machining, buffing, and pre-treatment to powder coating.

Summary of the invention:

Accordingly, the present invention provides a light weighting front fork system of a vehicle. The front fork system comprises an outer tube and an inner tube engaged to slide freely with respect to each other. The front fork system further comprises a piston assembly arranged within the inner tube to provide suspension to the vehicle under driving conditions. One end of the inner tube connects to a frame of the vehicle and one end of the outer tube is configured with a bore for receiving a front wheel axle of the vehicle therein.

The outer tube and the inner tube have shaped tubular body. The outer tube tubular body includes an inner circular surface where the outer tube and the inner tube engage to slide freely and an outer abuttable surface. The inner circular surface of the outer tube is either press fitted or moulded along with glass filed engineering plastic with a steel insert for structural stability and improving the sliding surface. The outer abuttable surface includes a dropout with a lower member for receiving the front wheel axle. The dropout with a lower member is made up of high performance engineering plastic.

The steel insert is made of a deep drawn tube with better surface finish, thereby reducing friction with the inner tube during fork compression and rebound movement. The high performance engineering plastic is moulded to required dimension with a pre bore into which the steel insert is press-fitted or optionally moulded.

Brief description of the drawings:

The objectives and advantages of the present invention will become apparent from the following description read in accordance with the accompanying drawings wherein,

Figure 1 illustrates an optional modification of the front fork shell build with special plastic and reinforced steel inserts, in accordance with the present invention;

Figure 2 shows a separate view of an inner tube of the front fork, in accordance with the present invention; and

Figure 3 shows a separate view of an outer tube of the front fork, in accordance with the present invention.

Detailed description of the invention:

The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiment.

The present invention provides front forks with a shorter processing path with an added advantage of light weighting, in-turn saving carbon foot print by eliminating the long and tedious supply chain activity of process in constructing front forks starting from casting, machining, buffing, and pre-treatment to powder coating.
This present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures. The components of the invention and the reference numbers are also listed in the table below:

Part No Part Name
100 Front fork system
10 Outer tube
20 Inner tube
30 Steel inserts
40 Special Plastic
50 Bore

Referring to figure 1, a light weighting front fork system (100) (hereinafter referred as, “the system (100)”) of a vehicle, in accordance with the present invention is shown. The system (100) is built with special plastic and reinforced steel inserts.

The system (100) of comprises an outer tube (10), an inner tube (20) engaged to slide freely with respect to each other, a piston assembly (not shown) arranged within the inner tube (20) to provide suspension to the vehicle under driving conditions. One end of the inner tube (20) connects to a frame of the vehicle body and one end of the outer tube (10) with a bore (50) receives a front wheel axle of the vehicle.

The outer tube (10) and inner tube (20) have a shaped tubular body. The outer tube (10) tubular body have an inner circular surface and an outer abuttable surface. The inner circular surface, where the outer tube (10) and inner tube (20) engages to slide freely, is either press fitted or moulded along with glass filed engineering plastic with the steel insert (30). The outer abuttable surface includes a dropout with a lower member for receiving a front wheel axle is made up of high performance glass filled engineering plastic (40) In an embodiment, the steel insert (30) is made of a deep drawn tube with better surface finish which reduces friction with direct inner tube (20) or may be in few cases integrated with DU® Bush during fork compression and rebound movement. The steel insert (30) improves the sliding surface and also provides structural stability.

The high performance engineering plastic (40) is moulded to the dimension required, with a pre bore into which steel insert (30) is press-fitted or optionally moulded. Also with an option of moulding engineering plastic with the steel tube inserted while in operation. In a specific embodiment, an aluminium casted outer tube (10) is replaced with a combination of the high performance engineering plastic moulded tube (40) with a pre bore into which the steel insert (30) is press-fitted or an option of moulding with a steel tube. Other dimensions related to mounting and assembly requirement remains same, i.e., the housing of DU® Bush, oil seal, circlip and dust seal for its functional requirement of front fork system (100). The steel insert (30) with required thickness is designed to compensate the strength requirements and is used as a strengthening and structural part, whereas plastic is used as a replacement to aluminum with re-enforcement.

Advantages of the invention:

1. The system (100) eliminates long and tedious supply chain activity of process starting from casting, machining, buffing, and pre-treatment to powder coating for constructing front fork system.
2. In the present system (100), providing a shorter processing path in constructing front fork with an added advantage of light weighting, in-turn saving carbon foot print.
3. Usage of standard deep drawn steel tube with better surface finish and size control to avoid a metal cutting operation of deep hole boring on Aluminium casted Outer tube.

The foregoing objects of the invention are accomplished and the problems and shortcomings associated with prior art techniques and approaches are overcome by the present invention described in the present embodiment. Detailed descriptions of the preferred embodiment are provided herein; however, it is to be understood that the present invention may be embodied in various forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but rather as a basis for the claims and as a representative basis for teaching one skilled in the art to employ the present invention in virtually any appropriately detailed system, structure, or matter. The embodiments of the invention as described above and the methods disclosed herein will suggest further modification and alterations to those skilled in the art. Such further modifications and alterations may be made without departing from the scope of the invention.
,CLAIMS:We claim:

1. A light weighting front fork system of a vehicle comprising:
an outer tube (10) and an inner tube (20) engaged to slide freely with respect to each other, wherein
• one end of the inner tube (20) connects to a frame of the vehicle, and
• one end of the outer tube (10) configured with a bore (50) for receiving a front wheel axle of the vehicle therein; and
a piston assembly arranged within the inner tube (20) to provide suspension to the vehicle under driving conditions;
characterized in that,
the outer tube (10) and the inner tube (20) having shaped tubular body such that the outer tube (10) tubular body includes,
• an inner circular surface where the outer tube (10) and the inner tube (20) engages to slide freely, wherein the inner circular surface of the outer tube (10) is either press fitted or moulded along with glass filled engineering plastic with a steel insert (30) for structural stability and improving the sliding surface., and
• an outer abuttable surface includes a dropout with a lower member for receiving the front wheel axle, wherein the dropout with a lower member is made up of high performance engineering plastic (40).

2. The light weighting front fork system of the vehicle as claimed in the claim 1, wherein the steel insert (30) is made of a deep drawn tube with better surface finish, thereby reducing friction with the inner tube (20) during fork compression and rebound movement.

3. The light weighting front fork system of the vehicle as claimed in the claim 1, wherein the high performance engineering plastic (40) is moulded to required dimension with a pre bore into which the steel insert (30) is press-fitted or optionally moulded.

Dated this 22nd day of January 2019s

Madhavi Vajirakar
(Agent for applicant)
IN/PA-2337