FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION A clutch release mechanism and a clutch device incorporating the same
APPLICANTS
TATA MOTORS LIMITED, an Indian company
having its registered office at Bombay House,
24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
INVENTORS
Janardhanan Venkatapathi,
Damodar Nageshwarrao Chollangi,
Medisetti Durgaprasad and Sopan V Musale.
All are Indian nationals of TATA MOTORS LIMITED,
an Indian company having its registered office at
Bombay House, 24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF INVENTION
The invention relates to a hydraulic and mechanical clutch actuation and release mechanism.
BACKGROUND OF THE INVENTION
The conventional clutch in an automobile consists of a clutch disc assembly, cover assembly and assembly release bearing. The clutch disc assembly is a friction element which is clamped against the engine flywheel through the cover assembly. The clutch disc assembly is sandwiched between the flywheel and the cover assembly and transmits the engine power to the gearbox.
The clutch engages / disengages only after a minimum amount of movement of the clutch release bearing. This movement of the clutch release bearing is achieved by the clutch linkage mechanism. The clutch linkage mechanism involves the clutch pedal unit and the linkages from the clutch pedal to the release mechanism at the clutch
In a conventional automobile, when the clutch pedal is pressed the clutch release bearing movement causes the clutch to disengage and when the clutch pedal is released the clutch engages.
The movement of clutch release bearing can be achieved through different mechanical / hydraulic means. Mechanical elements like clutch cross shaft / release yoke / release lever are also used to actuate the clutch release bearing. In all the systems the clutch release bearing slides over a guide tube. The clutch guide tube (cover tube) is further rigidly connected to the gear box housing. The position and orientation of the clutch release bearing with the cover tube is generally defined.

The cover tube is mounted on the gearbox in such a way that the axis is concentric with the gearbox driveshaft.
In particular applications, where smaller diameter clutch and larger size drive shafts from the gearbox are used, the conventional cover tube cannot be used due to space constraints. Use of conventional cover tubes will require higher clutch release bearing diameters and also results in fouling with the clutch cover rotational envelope.
OBJECT OF THE INVENTION
The object of the invention is to integrate the clutch release mechanism for smaller diameter clutches and larger diameter gearbox drive shafts.
Another object of the invention is to prevent fouling of the clutch release bearing with the clutch cover envelope by suitably designing the clutch cover tube.
SUMMARY OF THE INVENTION
The invention provides a clutch actuation/release mechanism that comprises a clutch release bearing capable of contacting with a resilient portion of a clutch pressure plate assembly on one side. A clutch cover tube is provided with guiding slots and the clutch release bearing is guided into the inner diameter of the clutch cover tube. The contact diameter of the clutch release bearing is chosen such that is matches the requirements of the clutch cover assembly.
The guiding slots provided in the cover tube facilitates the actuation of the clutch release bearing from outside and is capable of preventing rotation of the clutch release bearing. An outer race of the clutch release bearing is assembled on a support sleeve which is also guided into the inner diameter of the cover tube. The cover tube encompasses the clutch release bearing with the support sleeve.

In a preferred embodiment, a pair of protrusions are provided on the periphery of the support sleeve, which are guided into the slots of the cover tube. These slots on the cover tube on which the protrusions slide into also prevents rotary/radial movement of the support sleeve and the clutch release bearing.
In a preferred embodiment actuation of the support sleeve is achieved by a pair of yoke arms arranged on a common cross shaft. The yoke arms comprises a actuating portion which is capable of actuating the support sleeve in order to release the clutch.
BRIEF DESCRIPTION OF THE DRAWINGS
Referring now to the drawings wherein the showings are for the purpose of
illustrating preferred embodiments of the invention only, and not for purpose of
limiting the same:
Figure 1 shows the schematic layout of the clutch release mechanism with the
cover tube according to this invention;
Figure 2 shows the exploded view of the clutch device according to a first preferred
embodiment;
Figure 3 shows the assembled view of the clutch release bearing with the cover
tube;
Figure 4 shows the exploded view of the clutch device according to a second
preferred embodiment; and
Figure 5 shows the exploded view of the clutch device according to a third
preferred embodiment.
DETAILED DESCRIPTION OF THE INVENTION
The first preferred embodiment of the invention will be explained with reference to figures 1 to 3.

A clutch device typically comprises a clutch disc assembly (3) sandwiched between a flywheel (1) and a pressure plate assembly (12). The pressure plate assembly (12) is fastened to the flywheel (1) preferably by bolts (14) such that the pressure plate assembly (12) and the flywheel (1) rotate together. The clutch disc assembly (3) is connected with a gearbox drive shaft (9) through suitably splines (2).
A clutch release bearing (4) comprises an inner race (4A) and an outer race (4B). The inner race (4A) of the clutch release bearing (4) is contactable with a resilient portion (13) of the pressure plate assembly (12), preferably a diaphragm (13). The diaphragm (13) is formed as part of the pressure plate assembly (12) and rotates along with the pressure plate assembly (12). The outer race (4B) of the clutch release bearing (4) is assembled on a support sleeve (11) which is capable of being guided in the inner diameter of a cover tube (5).
The cover tube (5) is mounted on a transmission housing (10), preferably by bolts (6). The cover tube (5) is provided with guide slots (15) on at least two mutually opposite sides of the cover tube (5). The diameter of the cover tube is selected such that it can accommodate the outer diameter of the clutch release bearing (12) with the support sleeve (11).
When the support sleeve (11) of the clutch release bearing assembly is actuated it presses against the diaphragm (13) in the pressure plate assembly (12). The diaphragm (13) inturn releases the pressure on the clutch disc assembly (3) and hence releases the clutch for disconnecting the flywheel (1) from the gearbox driveshaft (9).
The support sleeve (11) is actuated by a pair of yoke arms (8) mounted on a common cross shaft (7). The common cross shaft (7) is connected to an external clutch release lever and mounted on a housing (not shown).

In the first preferred embodiment, the support sleeve (11) is provided with a pair of protrusions (16) located opposite to each other on the periphery of the sleeve (11). The protrusions (16) are guided into the slots (15) of the cover tube (5) such that any rotary and/or radial movement of the clutch release bearing assembly (4) or the support sleeve (11) is prevented due to the locking of the protrusions (16) within the slots (15).
As illustrated in figure 3, the protrusions (16) are guided and locked within the slots (15) of the cover tube (5) and the exposed portion of the inner race (4A) of the clutch release bearing (4) is exposed to be contactable with the diaphragm (13) of the pressure plate assembly (12). The yoke arms (8) includes a actuating portion (8A), which is also guided within the slots (15) of the cover tube (5) such that the actuating portion (8A) is in close proximity to, and preferably in contact with the protrusions (16) on the periphery of the support sleeve (11). In order to accomplish the disengagement of the clutch, the yoke arms is configured to apply sufficient force on the protrusions (16) to move the protrusions (16) along the slots (15) in order to actuate the support sleeve (11). When the support sleeve (11) fixed with the clutch release bearing (4) is actuated it presses against the diaphragm (13) in the pressure plate assembly (12). The diaphragm (13) inturn releases the pressure on the clutch disc assembly (3) and hence releases/disengages the clutch for disconnecting the flywheel (1) from the gearbox driveshaft (9).
In an alternate embodiment as illustrated in figure 4, the support sleeve (11) of the clutch release bearing (4) is modified. Instead of providing protrusions on the support sleeve, slots (18) are provided on the face of the support sleeve (11). The actuating portions (8A) or the yoke arms (8) has projecting pins (17) which is capable of being located and/or guided in the slot (18) on the support sleeve (11). The pin/slot combination ensures that any rotary and/or radial movement of the clutch release bearing assembly (4) or the support sleeve (11) is prevented. The bearing (4) has an inner part that is rotating and an outer part that is stationary due

to the pins (17) of the yoke arms (8) resting in the slot (18) of the sleeve (11). In this way the rotary/radial motion of the clutch release bearing with support sleeve is arrested. In order to accomplish the disengagement of the clutch, the actuating portions (8A) is configured to apply sufficient force to actuate the support sleeve (11) through the pins (17) located in the slots (18) on the support sleeve (11). The yoke arms (8) are actuated by any mechanical / hydraulic / electrical actuation methods viz. servo motors etc. The yoke arm (8) pushes the support sleeve (11) towards the engine side, to release the clutch. When the support sleeve (11) fixed with the clutch release bearing (4) is actuated it presses against the diaphragm (13) in the pressure plate assembly (12). The diaphragm (13) inturn releases the pressure on the clutch disc assembly (3) and hence releases/disengages the clutch for disconnecting the flywheel (1) from the gearbox driveshaft (9).
In an alternate embodiment as illustrated in figure 5, the support sleeve (11) of the clutch release bearing (4) is modified. Oblong cavities (19) are provided on the opposite sides on the peripheral portion of the support sleeve (11). The actuating portions (8A) or the yoke arms (8) has projecting pins (17) which is capable of being accommodated in the oblong cavities (19) on the support sleeve (11). The pin/oblong cavity combination ensures that any rotary and/or radial movement of the clutch release bearing assembly (4) or the support sleeve (11) is prevented. In order to accomplish the disengagement of the clutch, the actuating portions (8A) is configured to apply sufficient force to actuate the support sleeve (11) through the pins (17) located in the oblong cavities (19) on the support sleeve (11). The yoke arms is actuated by any mechanical / hydraulic / electrical actuation methods viz. servo motors etc. The yoke arm pushes the support sleeve towards the engine side to release the clutch. When the support sleeve (11) fixed with the clutch release bearing (4) is actuated it presses against the diaphragm (13) in the pressure plate assembly (12). The diaphragm (13) inturn releases the pressure on the clutch disc assembly (3) and hence releases/disengages the clutch for disconnecting the flywheel (1) from the gearbox driveshaft (9).

With the arrangements of any of the embodiments described above, a clutch of smaller diameter is possible to be used together with a gearbox driveshaft of a higher diameter. Also, the clutch release bearing contact diameter is able to be maintained optimally without causing fouling concerns with the clutch cover assembly envelope.
Many modifications and other embodiments of the invention may come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims.

WE CLAIM
1. A clutch release mechanism comprising:
a clutch release bearing (4) having an inner race (4A) contactable with a resilient
portion (13) of a pressure plate assembly (12) and an outer race (4B) assembled on
a support sleeve (11);
a clutch cover tube (5) having guiding slots (15) capable of receiving the support
sleeve (11) and the clutch release bearing (4) into an inner diameter of the clutch
cover tube (5);
restraining means (16) to prevent rotary and/or radial movement of the support
sleeve (11) and the clutch release bearing within the clutch cover tube (5); and
actuation means (8) capable of actuating the support sleeve (11) to release the
clutch.
2. The clutch release mechanism as claimed in claim 1, wherein the restraining means (16) includes a pair of protrusions extending on opposite sides on the periphery of the support sleeve (11) tight-fittingly inserted into the guiding slots (15) of the clutch cover tube (5) such that the rotary movement of the support sleeve (11) and the clutch release bearing (4) is prevented.
3. The clutch release mechanism as claimed in claim 1, wherein the actuation means includes a pair of yoke arms (8) having actuating portions (8A).
4. The clutch release mechanism as claimed in claim 2 and 3, wherein the actuating portions (8A) of the yoke arms (8) is capable of pushing the respective protrusions (16) along the guiding slots (15) to actuate the support sleeve (11).
5. The clutch release mechanism as claimed in claim 1, wherein slots (18) are provided on opposite sides on a face of the support sleeve (11).

6. The clutch release mechanism as claimed in claim 5, wherein the actuation means (8) includes a pair of yoke arms (8) having pins on its actuating portions (8A), said pins capable of locating in the slots (18) to actuate the support sleeve (11).
7. The clutch release mechanism as claimed in claim 1, wherein oblong cavities (19) are provided on opposite sides on the periphery of the support sleeve (11).
8. The clutch device as claimed in claim 7, wherein the actuation means (8) includes a pair of yoke arms (8) having pins on its actuating portions (8A), said pins capable of locating in the oblong cavities (19) to actuate the support sleeve (11).
9. The clutch device as claimed in claim 1, wherein the clutch cover tube (5) is mounted to a transmission housing (10).
10. A clutch device comprising a clutch disc assembly (3) sandwiched between a flywheel (1) and a pressure plate assembly (12) and a clutch release mechanism as claimed in any of the preceding claims.