Description:FORM 2
The Patent Act 1970
(39 of 1970)
&
The Patent Rules, 2005

COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

TITLE OF THE INVENTION
“HALFSHAFT ASSEMBLY FOR A VEHICLE”

Endurance Technologies Limited
E-92, M.I.D.C. Industrial Area, Waluj,
Aurangabad – 431136, Maharashtra, India

The following specification particularly describes and ascertains the nature of this invention and the manner in which it is to be performed.
This application is patent of addition of Indian Patent Application No. 202221066844 filed on 21st Nov. 2022 and the entire contents of which are specifically incorporated herein by reference.
Field of Invention

[001] The present invention is related to a halfshaft assembly for a vehicle. More particularly the invention is to provide a halfshaft assembly with improved the durability that minimizes backlash error, maintains desired contact area at any articulation angle between 0 to 21 degrees and drastically reduce the maintenance of the halfshaft assembly in vehicles with rear mounted engines and rear wheel drive that are subjected to higher articulation angles.

Background of the Invention

[002] Halfshaft is a vital component for transmitting power from engine to wheel which rotates at around 2000 – 3000 rpm particularly in rear wheel drive vehicles. It transmits the power from engine to wheels. Halfshaft must operate through continuously changing angles as per the road conditions between the Transmission and Wheel hub assembly.

[003] Conventionally available halfshaft, particularly for rear drive vehicles, has tulip at each of its ends which makes the housing arrangement for the spider assembly. The convoluted boots are placed over the tulip which protects the tulip and spider assembly from dirt, water, and other contaminants and also prevents grease leakage. This joint works with three rollers to transmit the rotations from the input to the output. In such designs three rollers are mounted on a spider legs. There is a slide fit between rollers and spider legs. This slide fit allows rollers to rotate very freely on spider legs. This spider assembly fits inside the mouth with three matching pockets, which is integrated with a flange and shaft. This pocket allows the joint to operate at an angle, but it also allows axial movement in the pocket without sacrificing drive.

[004] But this conventional design has limitation for the higher articulation angle. It cannot have length flexibility by changing any single part. It works on the dynamic contact between parts which creates backlash and this backlash is the major concern for early wear out of child components. Further, this design has complicated structure to transfer torque under the angles with flexibility and articulation. Additionally, this design requires the grease at both sides of flanges for the smooth functioning of the spider and roller and dissipation of the heat generated due to friction. The grease being a serviceable parameter, needs to replace at regular intervals requiring replacement of large clamps with hubs at both sides which consequently leads to high maintenance cost. In addition, to hold the boots in proper and fixed location, it require specialized clamps calling for additional cost as the replacement of clamps is a costly affair.

[005] Hence, there is a long pending and unmet requirement of a product that addresses the drawbacks of the conventional designs of the driveshaft and provide simple, economic and maintenance free solution. The present invention as described below fulfils the requirement.

Objectives of the Invention

[006] The main objective of the present invention is to provide a halfshaft assembly for a vehicle.

[007] Another objective of the present invention is to provide a halfshaft assembly for a vehicle that works under higher articulation angles.

[008] Further, the objective of the present invention is to provide a halfshaft assembly for a vehicle wherein said halfshaft assembly comprises a shaft and a pair of muff cups / flanges wherein said muff cup/flange is configured to have four equi-spaced uniquely profiled pockets on its inner surface to accommodate the bipod-roller assembly.

[009] The objective of the present invention is to provide a halfshaft assembly for a vehicle wherein a roller is mounted on each of the legs of bipod and the pockets in the muff cup / flange are profiled in such way that it maintains the desired contact surface area with the roller at any articulation angle.

[0010] Yet, the objective of the present invention is to provide a halfshaft assembly for a vehicle wherein the muff cup side mounting is structured in such a way that there is minimum contact of metal and boot during different articulation angles addressing the issue of wear and tear of the assembly.

[0011] Still another objective of the present invention is to provide a halfshaft assembly for a vehicle that improves product durability and minimizes backlash error.
[0012] Yet the objective of the present invention is to provide a halfshaft assembly for a vehicle that improves product durability with improved strengthening and drastically reduces the maintenance and the cost associated with it.

[0013] Further, the objective of the present invention is to provide a half shaft assembly for a vehicle that is very simple in construction and require no specialized manufacturing processes and materials.

Brief Description of the Drawings

[0014] This invention is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiment/s herein and advantages thereof will be better understood from the following description when read in conjunction with the following drawings, wherein

[0015] Figure 1 discloses isometric view of the halfshaft assembly at zero degree articulation angle in accordance with the present invention.

[0016] Figure 2 shows isometric view of the halfshaft assembly at higher (more than zero) degree articulation angle in accordance with the present invention.

[0017] Figure 3 (a, b and c) shows the different views (isometric, cut view and exploded view, respectively) of first embodiment of bipod-roller assembly attached with the shaft of the halfshaft as per present invention.

[0018] Figure 4 (a) presents the cut view of first embodiment of halfshaft assembly as per the present invention.
[0019] Figure 4 (b) presents the sectional view of muff cup / flange with first embodiment of bipod-roller assembly fitted therein as per the present invention.

[0020] Figure 5 (a, b and c) shows the different views (isometric, cut view and exploded view, respectively) of second embodiment of bipod-roller assembly attached with the shaft of the halfshaft as per the present invention.

[0021] Figure 6 (a and b) presents the sectional view of second embodiment of the bipod-roller assembly in accordance with the present invention.

[0022] Figure 7 shows isometric and front view of the equi-spaced uniquely profiled pockets in the inner surface of muff cup/flange as per the present invention.

[0023] Figure 8 shows sectional view of the equi-spaced uniquely profiled pockets with the pitch circle diameter of the roller guide surfaces in muff cup/flange as per the present invention.

[0024] Figure 9a shows sectional view of first embodiment of bipod-roller assembly mounted in equi-spaced uniquely profiled pockets of muff cup/flange as per the present invention.

[0025] Figure 9b shows enlarged sectional view of second embodiment of bipod-roller assembly mounted in equi-spaced uniquely profiled pockets of muff cup/flange as per the present invention.

Detailed Description of the Present Invention

[0026] Referring to Figs. 1, and 2, a halfshaft assembly (100) for a rear engine mounted and rear wheel drive vehicle comprises of a shaft (10), a pair of muff cups / flanges (12, 28), a pair of bellows (14), a plurality of metal clips (24 and 26), a pair of bipod-roller assembly (BP1, BP2) with one bipod-roller assembly mounted in flange (12) and other bipod-roller assembly mounted in flange (28). In the pair of muff cups / flange (12, 28), one of the muff cup / flange (12) is transmission side flange and the other muff cup / flange (28) is a wheel flange. The bipod-roller assembly comprises of a bipod pin (16) and a pair of rollers (20). The shaft (10) has a circular cross section throughout its length and it has two ends (10a and 10b). Further, the shaft (10) is configured to have bellow grooves (10G) and said grooves (10G) are equidistant from the center of the shaft (10).

[0027] The Figs. 3 and 4, show the first embodiment of bipod-roller assembly (BP1). In this embodiment, both ends (10a and 10b) of the shaft (10) are configured to have a ball shaped profile (18) with a thorough opening (30) therein to accommodate the bipod pin (16). The bipod pin (16) is configured to have main body portion (16M) and leg portions (16a and 16b) formed on either sides of the main body portion (16M) through a stepped profile (16T). The bipod pin (16) is press fitted in the opening (30) of the ball shaped profile (18) provided at either ends of the shaft (10). The fitting of the bipod pin (16) is done in the ball shaped profile (18) in such way that the legs (16a and 16b) of the bipod pin (16) are projected out from both sides of the opening (30) of the ball shaped profile (18). The roller (20) is mounted on the projected legs (16a and 16b) of the bipod pin (16).

[0028] The Figs. 5 and 6, show the second embodiment of bipod-roller assembly (BP2). In this embodiment, both ends (10a and 10b) of the shaft (10) are configured to have involute splines (10S) and a circlip groove (10C) at its distal end. The bipod pin (60) is configured to have main body portion (60M) and leg portions (60a and 60b) formed on either sides of the main body portion (60M) through a stepped profile (60T). The main body portion (60M) is configured to have a thorough opening (62) and said opening (62) has involute splines (60S) on its inner surface matching with the involute splines (10S) of the shaft (10). The bipod pin (60) is press fitted on the splined portion (10S) provided at either ends of the shaft (10) is locked there with a circlip (50) by mounting the circlip (50) in the circlip groove (10C). The fitting of the bipod pin (60) is done on the splined ends (10S) of the shaft (10) in such way that the legs (60a and 60b) of the bipod pin (60) are projected out from both sides of the main body portion (60M) of the bipod pin (60). The roller (20) is mounted on the projected legs (60a and 60b) of the bipod pin (60).

[0029] Referring to Figs. 7 and 8, the muff cups/flange (12 and 28) is configured to have four equi-spaced uniquely profiled pockets (40) on its inner surface to accommodate the bipod-roller assembly (BP1, BP2). The shaft (10) fitted with bipod pin (16, 60) and said bipod pin (16, 60) fitted with a roller (20) on each one of its legs (16a, 16b and 60a, 60b) is mounted in a pair oppositely profiled pockets (40) structured on the inner surface of the muff cup / flange (12, 28). The muff cup side mounting is structured in such a way that there is minimum contact of metal (i.e. the metal of the flange (12, 28) or of the shaft (10)) and boot / bellow (14) during different articulation angles addressing the issue of wear and tear of the bellow (14).

[0030] One end (10a) of the shaft (10) fitted with a bipod pin (16, 60) and a pair of rollers (20) is mounted inside the pair oppositely profiled pockets (40) structured on the inner surface of the muff cup / flange (12), and the other end (10b) of the shaft (10) fitted with a bipod pin (16, 60) and a pair of rollers (20) is mounted inside the pair oppositely profiled pockets (40) structured on the inner surface of the muff cup / flange (28). The joinery of the shaft (10) at its both ends (10a, 10b) with the muff cup / flange (12, 28) is covered with the rubber bellow (14). The bellow (14) is configured to have a shaft end (14a) and a flange end (14b); and the shaft end (14a) has its diameter smaller than that of the diameter of the flange end (14b). The shaft end (14a) of the rubber bellow (14) is inserted on the shaft (10) and fitted in the bellow groove (10G) of the shaft (10) tightly with the help of the metal clip (26). The other end (14b) of the rubber bellow (14) is inserted on the muff cup / flange (12, 28) and fitted in the groove (12G, 28G) tightly with the help of the metal clip (24) as shown in Fig. 1. The muff cup / flange is filled with the grease to facilitate lubrication to bipod-roller assembly (BP1, BP2). The bellow (14) restrict the entry of any foreign material, mud, dirt, etc. to enter in the muff cup / flange (12, 28).

[0031] Referring to Figs. 7 to 9, the muff cups/flange (12 and 28) is configured to have four equi-spaced uniquely profiled pockets (40) on its inner surface to accommodate the bipod-roller assembly. The said profiled pockets (40) structured on the inner surface of the muff cup / flange (12, 28) are configured to have a roller guide surfaces (40R) and each roller (20) is guided within said roller guide surfaces (40R). When the roller (20) is guided in the profiled pocket (40), the outer peripheral profile surface (20S) of the roller (20) forms a contact with the roller guide surface (40R) of the profiled pockets (40). The contact between outer peripheral profile surface (20S) of the roller (20) and said roller guide surfaces (40R) of the profiled pockets (40) of the flange (12, 28) is a circular contact and contact ratio of the said contact ranges from 1.67 to 1.88 for the shaft articulation ranging between 0 to 21 degrees for desired functioning of the bipod-roller assembly (BP1, BP2).

[0032] Referring to Fig. 9(a), the roller (20) is configured to have width (W) and the outer diameter (Od) and these two parameters of the roller (20) are in a specific proportion with each other as per the below given relation.
[(W) ÷ (Od)] = K
Where, ‘W’ is the width of the roller, and
‘Od’ is the outer diameter of the roller
The ratio (K) of the width (W) of the roller (20) to the outer diameter (Od) of said roller (20) is in the range of 0.33 to 0.42. Referring to Figs. 8 and 9(a), the roller guide surfaces (40R) of the profiled pockets (40) is configured to have a pitch circle diameter (PCD) and said PCD is in a specific proportion with the width (W) of the roller (20) as per the given relation for the shaft articulation ranging between 0 to 21 degrees for functioning of the bipod-roller assembly as per the intent of the present invention.
KR1 = [ (W) ÷ (PCD) ]
Where, ‘W’ is the width of the roller, and
‘PCD’ is the pitch circle diameter
The ratio (KR1) of the width (W) of the roller (20) to the pitch circle diameter (PCD) of said roller guide surfaces (40R) of the profiled pockets (40) varies in the range from 0.25 to 0.31. The outer diameter (Od) of the roller (20) is also in a specific proportion with the pitch circle diameter (PCD) of said roller guide surfaces (40R) of the profiled pockets (40) as per the given relation for the shaft articulation ranging between 0 to 21 degrees for functioning of the bipod-roller assembly as per the intent of the present invention.
KR2 = [ (Od) ÷ (PCD) ]
The ratio (KR2) of the outer diameter (Od) of the roller (20) to the pitch circle diameter (PCD) of said roller guide surfaces (40R) of the profiled pockets (40) is in the range of 0.67 to 0.87.

[0033] The unique construction of the halfshaft assembly (BP1, BP2) of the invention comprising a pair of muff cups / flange (12, 28) configured to have four equi-spaced uniquely profiled pockets (40) on its inner surface to accommodate the bipod-roller assembly (BP1, BP2); a roller (20) mounted on each of the legs (16a, 16b, 60a, 60b) of bipod pin (16, 60) and a circlip (50) intelligently placed in the groove (10C) to lock and restrict the axial movement of the bipod pin (60); and the parameters of the roller (20) viz. width (W) and outer diameter (Od) establishing a specific relationship with the roller guide surface (40R) and pitch circle diameter (PCD) of a pair oppositely profiled pockets (40) structured in muff cup / flange (12, 28) improves the torque transmission efficiency and reduces backlash error as per the vehicle requirement.

[0034] As far as the working of this invention is concerned, when the vehicle with rear mounted engine and rear wheel drive runs on the road surface, the transmission output shaft center and wheel center are in the different planes. In this condition, to transmit the torque efficiently from transmission output shaft to wheel hub, the uniquely structured bipod-roller assembly (BP1, BP2) of the halfshaft of the invention slides intelligently within the uniquely profiled pockets (40) provided on the inner surface of the muff cup / flange (12, 28) and facilitate the transfer of torque without any backlash error and improved articulation angle. In this invention backlash error is addressed by maintaining the limited but required contact area (CR) between the outer peripheral surface (20R) of the roller (20) and the roller guide surface (40R) of the profiled pockets (40) formed on the inner surface of the muff cup / flange (12, 28). This is achieved by rolling and sliding movement of the rollers within the profiled pockets (40) of the muff cup / flange (12, 28). Metal clips (24, 26) rigidly locks the position of the bellow (14) on the muff cup / flange (12, 28) and the shaft (10) thereby eliminating the entry of any foreign material inside the muff cup.

[0035] The technical advantages achieved by the embodiments of the present invention and thereby the inventive contribution to the technology domain of the halfshaft assembly are as under:
- It achieves higher articulation angles and improves product durability.
- Facilitate for higher torque and load taking capacity and minimizes the backlash error.
- The embodiment of the invention efficiently transfer the torque and provides maintenance free product.
- The requirement of bellow hub, retainer ring, spider roller units, springs, etc. (as is required in the conventional units) is totally eliminated thereby leading to reduction in weight and cost of the halfshaft assembly.
- The embodiment of the invention is very much effective in the vehicles that are operated on the undulating road surfaces (specifically on the roads in rural areas) where more articulation angle is required due to uneven road surfaces for efficiently transfer of the torque.
- The embodiment of the invention has wide applications in defence vehicles and vehicles that operate in higher altitude terrains with off-road applications. The embodiment facilitate to offer a higher ground clearance.
- The invention provides very simple and easy to manufacture halfshaft assembly that drastically reduces wear out of child parts.
- It does not require any of the specialized processes of manufacturing, heat treatment and finishing.
- The design of the embodiments leads to significant reduction of weight thereby improving the vehicle fuel efficiency and drivability.

[0036] The foregoing description of the specific embodiment of the invention will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiment. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiment herein has been described in terms of preferred embodiment, those skilled in the art will recognize that the embodiment herein can be practiced with modification within the spirit and scope of the embodiment as described herein. , Claims:We Claim

1. A halfshaft assembly (100) for a vehicle, the vehicle with rear mounted engines and rear wheel drive, comprising of a shaft (10), a pair of muff cups / flanges (12, 28), a pair of bellows (14), a pair of bipod-roller assembly (BP1, BP2) and a plurality of metal clips (24 and 26);
wherein,
- bipod-roller assembly (BP1, BP2) comprises of a bipod pin (16, 60) and a pair of rollers (20), and said rollers (20) are mounted on the projected legs (16a, 16b and 60a, 60b) of the bipod pin (16, 60);
- the muff cups/flange (12 and 28) is configured to have four equi-spaced uniquely profiled pockets (40) on its inner surface to accommodate the bipod-roller assembly (BP1, BP2);
- the bellow (14) is configured to have a shaft end (14a) and a flange end (14b); and
- the joinery of the shaft (10) at its both ends (10a and 10b) with the muff cup / flange (12, 28) is covered with the rubber bellow (14) by inserting the shaft end (14a) and the flange end (14b) of the rubber bellow (14) over the shaft (10) and the muff cup / flange (12, 28), respectively.

2. The halfshaft assembly (100) as claimed in claim 1, wherein
- the bipod pin (16) is configured to have main body portion (16M) and leg portions (16a and 16b) formed on either sides of the main body portion (16M) through a stepped profile (16T);
- the shaft (10) has ends (10a and 10b) and each of the ends of the shaft (10) is configured to have a ball shaped profile (18) with the thorough opening (30) therein to accommodate the bipod pin (16); and
- the bipod pin (16) is press fitted in the opening (30) of the ball shaped profile (18) provided at either ends (10a and 10b) of the shaft (10) such that the legs (16a and 16b) of the bipod pin (16) are projected out from both sides of the opening (30) of the ball shaped profile (18).

3. The halfshaft assembly (100) as claimed in claim 1, wherein
- the bipod pin (60) is configured to have main body portion (60M) and leg portions (60a and 60b) formed on either sides of the main body portion (60M) through a stepped profile (60T);
- said main body portion (60M) of the bipod pin (60) has a thorough opening (62) and said opening (62) has a plurality of involute splines (60S) on its inner surface matching with the involute splines (10S) of the shaft (10);
- the shaft (10) has ends (10a and 10b) and each of the ends of the shaft (10) is configured to have involute splines (10S) and a circlip groove (10C) at its distal end; and
- the bipod pin (60) is press fitted on the splined portion (10S) provided at either ends of the shaft (10) and is locked there with a circlip (50) by mounting the circlip (50) in the circlip groove (10C) such that the legs (60a and 60b) of the bipod pin (60) are projected out from both sides of the main body portion (60M) of the bipod pin (60).

4. The halfshaft assembly (100) as claimed in any of the claims 2 and 3, wherein
- the shaft end (14a) of the bellow (14) is tightly fitted in the bellow groove (10G) of the shaft (10) with the metal clip (26);
- the flange end (14b) of the bellow (14) is tightly fitted in the groove (12G, 28G) of the muff cup / flange (12, 28) with metal clip (24); and
- said muff cup / flange (12 and 28) is filled with the grease to facilitate lubrication to bipod-roller assembly (BP1, BP2).

5. The halfshaft assembly (100) as claimed in claim 4, wherein
- the end (10a) of the shaft (10) is fitted with bipod-roller assembly (BH1, BP2) and said end (10a) is mounted inside a pair of oppositely profiled pockets (40) structured on the inner surface of the muff cup / flange (12); and
- the end (10b) of the shaft (10) is fitted with bipod-roller assembly (BP1, BP2) and said end (10b) is mounted inside a pair of oppositely profiled pockets (40) structured on the inner surface of the muff cup / flange (28).

6. The halfshaft assembly (100) as claimed in claim 5, wherein
- the profiled pockets (40) structured on the inner surface of the muff cup / flange (12, 28) are configured to have a roller guide surfaces (40R) and each roller (20) being guided within said roller guide surfaces (40R); and
- the contact between outer peripheral profile surface (20S) of the roller (20) and said roller guide surfaces (40R) of the profiled pockets (40) of the flange (12, 28) is circular contact (CR) with a contact ratio ranging from 1.67 to 1.88 for articulation ranging between 0 to 21 degrees for desired functioning of the bipod-roller assembly.

7. The halfshaft assembly (100) as claimed in claim 6, wherein the ratio (K) of the width (W) of the roller (20) to the outer diameter (Od) of said roller (20) is in the range of 0.33 to 0.42.

8. The halfshaft assembly (100) as claimed in claim 7, wherein the ratio (KR1) of the width (W) of the roller (20) to the pitch circle diameter (PCD) of said roller guide surfaces (40R) of the profiled pockets (40) is in the range 0.25 to 0.31.

9. The halfshaft assembly (100) as claimed in claim 8, wherein the ratio (KR2) of the outer diameter (Od) of the roller (20) to the pitch circle diameter (PCD) of said roller guide surfaces (40R) of the profiled pockets (40) is in the range 0.67 to 0.87.

Dated this 10th day of Mar. 2023

Sahastrarashmi Pund
Head – IPR
Endurance Technologies Ltd.

To,
The Controller of Patents,
The Patent Office, at Mumbai