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

COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

TITLE OF THE INVENTION
“TRIPOD CONSTANT VELOCITY JOINT FOR HALFSHAFT ASSEMBLY OF A VEHICLE”

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

The following specification particularly describes and ascertains the nature of this invention and the manner in which it is to be performed.

Field of Invention

[001] The present invention is related to a tripod constant velocity joint for halfshaft assembly of a vehicle. More particularly the present invention relates to the spider and roller assembly having a uniquely profiled lubrication system employed therein to facilitate the lubrication of the tripod constant velocity joint of a vehicle.

Background of the Invention

[002] Tripod type constant velocity joints are well known in the automobile industry as one type of constant velocity joints used in the drive system of vehicles for transferring a uniform torque and a constant speed, while operating with a wide range of joint angle. The said constant velocity (CV) joints includes a spider and roller assembly to transmit the torque between the drive shaft and the driven shaft while accommodating angular misalignments. The spider and roller assembly is an essential component within CV joints. The spider comprises a central opening with radially extending out trunnions. Each trunnion supports a roller designed to facilitate the torque transmission and accommodate a variety of angular alignments. The central opening of the spider is positively connected to the drive shaft, and as the output shaft of the transmission rotates, the torque is transmitted through the central opening to the halhshaft / driveshaft. The spherical rollers allow the trunnions to move smoothly within the tripod housing / flange to get adjusted in response to different articulation angles subjected by the irregularity of the road. This movement is crucial for accommodating angular alignments between the drive shaft and the driven shaft, ensuring constant velocity transmission. Additionally, the spherical rollers help distribute the load evenly across the contact surfaces, reducing stress concentrations and extending the lifespan of the components.
[003] Conventional designs still face issues related to wear and tear, misalignment, inadequate lubrication, material fatigue, excessive skewing, load distribution, and thermal expansion. One of the major issues in existing tripod joint designs is insufficient lubrication at the interface between the spider’s trunnions and the rollers. In many conventional spider and roller assembly, lubricant is not evenly distributed across the contact surfaces, particularly in areas where the roller moves along the trunnion to get adjusted to the changing articulation angle. As a result, dry friction occurs at mating surfaces, leading to increased heat generation, wear and tear followed by eventual failure of the joint over the period of time. This happens because the conventional tripod and roller assemblies of CV joints are devoid of having dedicated lubrication system. The conventional lubrication system is of filling the housing / transmission and wheel flange with grease which over the period of time loses its viscosity creating the friction at the mating surfaces of the trunnions and rollers. Furthermore, the lack of effective lubricant distribution leads to premature degradation of the components, reducing the lifespan of the CV joint and increasing maintenance costs.

[004] Another issue in conventional design is this experiences excessive contact stress which leading to surface fatigue. Said this fatigue can result in cracking of the contact surfaces, which reduces the integrity of the spider roller joint. When the contact surfaces of the roller and spider degrade, the joint loses its ability to transmit torque smoothly, causing vibration, unwanted noise, and loss of efficiency. Existing designs often do not account for optimal alignment between lubrication grooves on the trunnions and rollers. Therefore, these conventional arrangement results in non-uniform lubrication, leaving some parts of the trunnion and roller surfaces more prone to pre-mature wear and tear. This issue is particularly severe under dynamic operating conditions, where the lack of alignment leads to inconsistent lubricant flow, causing uneven wear patterns and increasing the risk of failure of the spider roller / CV joint.
[005] Therefore, there is a need for an improved tripod roller constant velocity joint having a uniquely profile spider and roller assembly that addresses these challenges, providing a more reliable and efficient solution for lubrication of CV joints employed in automotive drive systems. The present invention aims to overcome these limitations by intelligently providing optimized lubrication on the spider and roller assembly of the tripod constant velocity joint, ensuring desired lubrication in extreme conditions, an enhanced performance and longevity in the CV joint applications.

Objectives of the Present Invention

[006] The main objective of the present invention is to provide a tripod and roller constant velocity joint for a vehicle.

[007] Another objective of the present invention is to provide an improved spider and roller assembly for the constant velocity joint having the uniquely profiled means for lubricating the spider trunnions and rollers of the said spider and roller assembly.

[008] Further, the objective of the present invention is to provide a spider of halfshaft assembly having a plurality of uniquely profiled axial and radial grooves facilitating the uniform distribution of lubricant over the outer peripheral surface of the trunnions of the spider and thus reducing the friction thereby.

[009] Yet another objective of the invention is to provide a roller having a plurality of uniquely profiled axial grooves facilitating the uniform distribution of lubricant over the inner peripheral surface of the roller and thus reducing the friction thereby
[0010] Still another objective of the present invention is to increase the lifespan and durability of the spider and roller of the halfshaft assembly by minimizing the wear and friction by employing an optimized lubrication preventing premature failure and ensuring consistent performance.

[0011] Further, the objective of the present invention is to provide a tripod constant velocity joint having an improved durability and reduced maintenance cost.

Brief Description of Drawings

[0012] This invention is illustrated in the accompanying drawings, throughout which like reference letters indicate corresponding parts in the various figures. The embodiments herein and advantages thereof will be better understood from the following description when read with reference to the following drawings, wherein

[0013] Figure 1 shows sectional view of the tripod and roller assembly of constant velocity joint housed in the flange in accordance with the present invention.

[0014] Figure 2 presents an isometric view of spider and roller assembly in assembled condition as per the present invention.

[0015] Figure 3 shows the assembled view of the spider and roller assembly disclosing the lubrication system between the mating surfaces of roller and trunnion of the spider as per the preferred embodiment of the present invention.

[0016] Figures 4 and 5 disclose the perspective view and the front view of the spider, respectively with the uniquely profiled lubrication grooves thereon as per the first preferred embodiment of the present invention.

[0017] Figures 6 and 7 disclose the perspective view and the front sectional view of the roller in accordance with the first preferred embodiment of the present invention.

[0018] Figures 8a to 8f shows the top views of the spider and roller assembly disclosing the different embodiments / sections of the lubrication grooves in accordance with the present invention.

Detailed Description of the Present Invention

[0019] The invention will now be described in detail with reference to the accompanying drawings which must not be viewed as restricting the scope and ambit of the invention. Referring to Fig. 1, a tripod constant velocity joint (500) for a vehicle comprises of a halfshaft (50), a wheel / transmission flange (100) and a spider and roller assembly (200). The said spider and roller assembly (200) includes a spider (300) with a plurality of trunnions (320) and a plurality of rollers (400).

[0020] The wheel / transmission flange (100) is configured to have a cup-like profile having an internal cavity (100C) to house the spider and roller assembly (200). The cavity (100C) of the wheel / transmission flange (100) has an inner peripheral surface configured to have three pockets (110) extending in an axial direction of the trunnions (320) and have an equiangular orientation with each other. Each of the pockets (110) has track groove surfaces (115) extending in the axial direction on both sides of each of the said pockets (110). These track groove surfaces (115) are configured to articulate and guide the rollers (400) of the spider and roller assembly (200) during the working condition of the tripod constant velocity joint (500).

[0021] Referring to Figs. 2 and 3, the spider (300) is configured to have a spider body (310) and three spider trunnions (320) each projected into a radial direction from the said spider body (310). The spider body (310) has an opening (315) at its center and said opening (315) of the spider body (310) is configured to accommodate the shaft (50). In one of the embodiments of the spider body, the said opening (315) has a plurality of splines (315S) formed at its inner peripheral surface and the meshing end of the halfshaft (50) has a plurality of the matching splines (50S) formed over its outer peripheral surface which gets fitted with the splines (315S) of the spider body (310) thereto and thereby ensures the positive locking of the halfshaft (50) with the spider (300). In another embodiment of the spider body (310), the said opening (315) has a plurality keyways formed at its inner peripheral surface and the meshing end of the halfshaft (50) has a plurality of the matching keys formed over its outer peripheral surface which gets fitted in the keyways of the spider body (310) thereto and thereby ensures the positive locking of the halfshaft (50) with the spider (300).

[0022] The spider body (310) has at least three trunnions (320) projecting out from a flat resting surface (320RF) of the said spider body (310) and said trunnions (320) maintains an equiangular distance of 120° from each other. The trunnions (320) are positioned on the flat resting surface (320RF) of the said spider body (310) in a manner such that a relief groove (320G) is formed at the interfacial region in between the resting surface (320RF) and the trunnions (320). This relief groove (320G) helps preventing the collision between the rollers (400) and the spider body (310) in the case of large angles of deflection / articulation of the halfshaft (50) during the working condition of the tripod constant velocity joint (500).

[0023] The trunnions (320) of the spider (300) are configured to have a plurality of axial grooves (320AG) and at least one radial groove (320RG) on its outer peripheral surface. The said axial grooves (320AG) and the radial grooves (320RG) are configured to store lubricant therein so as to facilitate the lubrication of the trunnions (320) of the spider (300) in its working condition. The axial grooves (320AG) are provided in an equiangular relation to each other wherein the said grooves (320AG) may range from a minimum three grooves to a maximum five grooves. The said radial groove (320RG) maintains an orthogonal relation with the axial grooves (320AG) of the trunnions (320). The orthogonal configuration of radial grooves (320RG) and axial grooves (320AG) enhances lubrication efficiency and provides continuous and even distribution of lubricant across the mating surfaces of the spider trunnions (320) and rollers (400).

[0024] Referring to the Fig. 3, the roller (400) is configured to have a donut shaped profile having a circular central opening (400H) to accommodate the trunnion (320) of the spider (300). The peripheral surface of central opening (400H) of the said roller (400) is configured to have a plurality of axial grooves (400AG) positioned at an equiangular relation to each other wherein the said grooves (400AG) may range from a minimum three grooves to a maximum five grooves.

[0025] The spider and roller assembly (200) is formed by fitting the rollers (400) over the trunnions (320) of the spider (300). The rollers (400) are snuggly sleeved over the trunnions (320) of the spider (300) in a manner such that axial grooves (400AG) of the rollers (400) overlaps with the axial grooves (320AG) of the trunnions (320) of the spider (300) in assembled condition. This overlap of the axial grooves (320AG) of the trunnions (320) of the spider (300) and the axial grooves (400AG) of the roller (400) leads to the formation of a lubrication channel (LC) wherein the said lubrication channel (LC) is configured to hold the required amount of lubricant for lubricating the spider and roller assembly (200). Further, the rollers (400) of the spider and roller assembly (200) are positioned in the pockets (110) of the wheel / transmission flange (100) to form the tripod constant velocity joint (500).

[0026] The lubrication channel (LC) ensures the efficient distribution of the lubricant across the contact surfaces of the trunnions (320) of the spider (300) and the rollers (400) of the spider and roller assembly (200). The axial grooves (320AG) and the radial groove (320RG) of the spider trunnion (320) and the axial grooves (400AG) of the rollers (400) are configured to have semicircular profiles in accordance with the first embodiment of the present invention (refer Figs. 4 to 7). The said semicircular profiled grooves (320AG, 320RG) of the spider trunnion (320) and the semicircular profiled grooves (400AG) of the rollers (400) are configured to have equal radius “r” which consequently forms a circular shaped lubrication channel (LC) in the assembled condition of the spider roller assembly. The said grooves (320AG, 320RG, 400AG) are intelligently optimized in a manner to impart an efficient lubrication and reduce the working friction between the spider trunnion (320) and the rollers (400) of the spider and roller assembly (200) in accordance with the below mentioned relation:
r = k*√R
wherein,
r is the radius of the axial / radial groove of the trunnion and rollers;
R is the radius of the trunnion (320) of the spider; and
k is the lubrication constant, wherein the k ranges from 0.2 to 0.5.
[0027] Further, the radial groove (320RG) of the spider (300) is positioned at an optimized distance “a” from the top edge of the trunnion (320) of the spider (300). The said distance “a” needs to be very wisely maintained at a specific proportion in relation to the total height “h” of the trunnion (320) as mentioned bellows:
a = c*h
wherein:
a is the distance of the radial groove from the top edge of the trunnion;
h is the total height of the spider trunnion; and
c is the proportionality constant wherein c ranges from 0.4 to 0.6.

[0028] Referring to the Figs. 8a - 8f, the lubrication channel (LC) of the spider and roller assembly (200) may be modified to have a variety of sectional profiles of the lubrication channel (LC) and said profiles are selected from circular, pentagon, triangular, square, rectangular and octagonal profiles respectively as per the other embodiments of the present invention. Thus, the spider and roller assembly (200) of the tripod joint (500) having the uniquely profiled lubrication channel (LC) helps in reducing the friction, minimizes wear, and enhances the operational efficiency and lifespan of the said tripod joint.

[0029] As far as the working of this invention is concerned when the vehicle runs on an even road surface, the spider and roller assembly (200) of the tripod constant velocity joint (500) rotates in unison with the transmission output shaft due to the constraining of the rollers (400) within the uniquely profiled pockets (110) of the wheel / transmission flange (100). When the vehicle runs on an uneven 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 rollers (400) of the spider and roller assembly (200) slides intelligently within the uniquely profiled pockets (110) provided on the inner surface of the wheel / transmission flange (100) and facilitate the transfer of torque by articulating the halfshaft (50) at a variety of articulation angles. The grooves (320AG, 400AG) of the lubrication channel (LC) displace from their initial overlapping condition and thus distributes the lubricant uniformly over the outer peripheral surface of the trunnions (320) of the spider (300) and over the inner peripheral surface of the rollers (400).

[0030] The tripod constant velocity joint (500) of the present invention in accordance with the discussed embodiment provides the following technical advantages that contribute to the technical advancement of the constant velocity joints as far as the efficient lubrication of said joints for the vehicles are concerned as briefed below:
- It reduces the friction, heat generation, and wear, thereby extending the service life of the assembly.
- Enhances the flexibility, overall performance and durability of the tripod joint.
- The proportional relationship between the height of the trunnion and the distance from the top edge, defined by (a =c*h), ensures optimal placement of radial grooves. This precise placement facilitates efficient lubrication and reduces maintenance requirements.
- The derived equations for groove dimensions and spacing provide clear guidelines for manufacturing, ensuring that components are produced to precise specifications. This flexibility in design and manufacturing enhances the reliability and performance of the assembly.
- The combination of reduction in friction, balanced load distribution, and optimal lubrication results in an extended service life for the spider and roller assembly. This longevity translates to lower maintenance costs and improves cost-effectiveness over time.
- These advantages contribute to a more efficient, durable, and adaptable tripod spider and roller assembly, addressing common issues such as friction, wear, and misalignment more effectively than existing design.

[0031] The foregoing description of the specific embodiment/s 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 tripod constant velocity joint (500) for halfshaft assembly of a vehicle comprising of a halfshaft (50), a wheel / transmission flange (100) and a spider and roller assembly (200), said spider and roller assembly (200) comprising of a spider (300) with a plurality of trunnions (320) and a plurality of rollers (400)
wherein,
- the spider (300) is configured to have a spider body (310) and three spider trunnions (320) each projected into a radial direction from the said spider body (310);
- said trunnions (320) of the spider (300) are configured to have a plurality of axial grooves (320AG) and at least one radial groove (320RG) on its outer peripheral surface;
- each of the rollers (400) is configured to have a donut shaped profile having a circular central opening (400H) to accommodate the trunnion (320) of the spider (300); and the peripheral surface of said central opening (400H) is configured to have a plurality of axial grooves (400AG) positioned at an equiangular distance to each other;
- said rollers (400) are snuggly sleeved over the trunnions (320) of the spider (300) in a manner such that axial grooves (400AG) of the rollers (400) are configured to overlap with the axial grooves (320AG) of the trunnions (320) of the spider (300) to form a lubrication channel (LC) in assembled condition of the spider roller assembly (200); and
- said spider and roller assembly (200) is positioned in the pockets (110) of the wheel / transmission flange (100) to form the tripod constant velocity joint (500).

2. The tripod constant velocity joint (500) for halfshaft assembly of a vehicle as claimed in claim 1, wherein
- the axial grooves (320AG) on the trunnion (320) of the spider (300) are positioned at an equiangular distance with each other;
- said axial grooves (320AG) varies from a minimum three grooves to a maximum five grooves;
- the radial groove (320RG) are configured to maintain an orthogonal relation with the axial grooves (320AG) of the trunnions (320), and said orthogonal configuration of radial grooves (320RG) and axial grooves (320AG) is configured to enhance lubrication efficiency by providing continuous and even distribution of lubricant across the mating surfaces of the spider trunnions (320) and rollers (400);
- the axial grooves (400AG) of the roller (400) varies from a minimum three grooves to a maximum five grooves; and
- said axial grooves (320AG) and the radial grooves (320RG) on the trunnion (320) and axial grooves (400AG) on the rollers (400) are configured to store lubricant therein so as to facilitate the lubrication of the trunnions (320) and rollers (400) of the spider roller assembly (200) in its working condition.

3. The tripod constant velocity joint (500) for halfshaft assembly of a vehicle as claimed in claim 2, wherein
- the axial grooves (320AG) and the radial groove (320RG) of the spider trunnion (320) and the axial grooves (400AG) of the rollers (400) are configured to have semicircular profile;
- said semicircular profiled grooves (320AG, 320RG) of the spider trunnion (320) and the semicircular profiled grooves (400AG) of the rollers (400) have the equal radius “r” thereby forming a circular cross-sectional profile of the lubrication channel (LC) in the assembled condition of the spider roller assembly (200); and
- said lubrication channel (LC) is configured to ensure an efficient distribution of the lubricant across the contact surfaces of the trunnions (320) of the spider (300) and the rollers (400) of the spider and roller assembly (200).

4. The tripod constant velocity joint (500) for halfshaft assembly of a vehicle as claimed in claim 3, wherein
- the lubrication channel (LC) of the spider and roller assembly (200) is configured to have a variety of sectional profiles of the lubrication channel (LC) and said sectional profiles are selected from circular, pentagon, triangular, square, rectangular, octagonal and combination of thereof; and
- the spider and roller assembly (200) of the tripod joint (500) having these uniquely profiled lubrication channel (LC) are configured to reduce the friction, minimize wear, and enhance the operational efficiency and lifespan of the said tripod joint.

5. The tripod constant velocity joint (500) for halfshaft assembly of a vehicle as claimed in claim 3, wherein said grooves (320AG, 320RG, 400AG) are intelligently optimized in a manner to impart an efficient lubrication and reduce the working friction between the spider trunnion (320) and the rollers (400) of the spider and roller assembly (200); and the radius (r) of the lubrication channel (LC) is configured to maintain a relation with the radius (R) of the trunnion (320) of the spider (300) as r = k*√R ; wherein ‘r’ is the radius of the axial / radial groove of the trunnion and rollers, ‘R’ is the radius of the trunnion (320) of the spider, and ‘k’ is the lubrication constant and said ‘k’ varies in the range of 0.2 to 0.5.

6. The tripod constant velocity joint (500) for halfshaft assembly of a vehicle as claimed in claim 5, wherein the radial groove (320RG) of the spider (300) is positioned at an optimized distance “a” from the top edge of the trunnion (320) of the spider (300); and said distance “a” maintains a specific proportion in relation to the total height “h” of the trunnion (320) as a = c*h ; wherein ‘a’ is the distance of the radial groove from the top edge of the spider trunnion, ‘h’ is the total height of the spider trunnion, and ‘c’ is the proportionality constant wherein c ranges from 0.4 to 0.6.

7. The tripod constant velocity joint (500) for halfshaft assembly of a vehicle as claimed in claim 6, wherein
- the spider (300) has an opening (315) at the center of the spider body (310) and said opening (315) of the spider body (310) is configured to accommodate the halfshaft (50)
- the spider body (310) has at least three trunnions (320) projecting out from a flat resting surface (320RF) of the said spider body (310) and said trunnions (320) maintains an equiangular distance of 120° from each other;
- said trunnions (320) are positioned on a flat resting surface (320RF) of the said spider body (310) in a manner such that a relief groove (320G) is formed at the interfacial region in between the resting surface (320RF) and the trunnions (320); and
- said relief groove (320G) is configured to prevent the collision between the rollers (400) and the spider body (310) extreme articulation of the halfshaft (50) during the working condition of the tripod constant velocity joint (500).

8. The tripod constant velocity joint (500) for halfshaft assembly of a vehicle as claimed in claim 7, wherein
- the opening (315) of the spider body (310) has a plurality of splines (315S) formed at its inner peripheral surface;
- the meshing end of the halfshaft (50) has a plurality of the matching splines (50S) formed over its outer peripheral surface; and
- said splines (50S) of the halfshaft (50) are configured to get fitted with the splines (315S) of the spider body (310) so as to ensure the positive locking of the halfshaft (50) with the spider (300) inside the wheel / transmission flange (100).

9. The tripod constant velocity joint (500) for halfshaft assembly of a vehicle as claimed in claim 7, wherein
- the opening (315) of the spider body (310) has a plurality keyways formed at its inner peripheral surface;
- the halfshaft (50) has a plurality of the matching keys formed over its outer peripheral surface; and
- said keys on the halfshaft (50) are configured to get fitted in the keyways of the spider body (310) so as to ensure the positive locking of the halfshaft (50) with the spider (300) inside the wheel / transmission flange (100).

10. The tripod constant velocity joint (500) for halfshaft assembly of a vehicle as claimed in any of the claims 8 and 9, wherein
- the wheel / transmission flange (100) is configured to have a cup-like profile having an internal cavity (100C) to house the spider and roller assembly (200);
- said cavity (100C) of the wheel / transmission flange (100) has an inner peripheral surface configured to have three pockets (110) extending in an axial direction of the trunnions (320) and have an equiangular orientation with each other;
- each of the pockets (110) is configured to have track groove surfaces (115) extending in the axial direction on both sides of each of the said pockets (110); and
- said track groove surfaces (115) are configured to articulate and guide the rollers (400) of the spider and roller assembly (200) during the working condition of the tripod constant velocity joint (500) in response to different articulation angles.

Dated this 22nd day of Jan. 2025

Sahastrarashmi Pund
Head – IPR
Endurance Technologies Ltd.

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