DESC: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
“CENTRIFUGAL MULTIPLATE WET CLUTCH FOR VEHICLES”

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

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

Field of Invention

[001] The present invention is related to clutch for a vehicle. More particularly, the invention is related to centrifugal clutches for two wheeled motor vehicles, preferably bikes and scooters, wherein the centrifugal clutch is provided with lever mechanism to enable manual disengagement or delayed engagement of the clutch thereby allowing both automatic and manual operation of the centrifugal clutch.

Background of the Invention

[002] Conventional centrifugal multiplate wet clutch for motor vehicle are provided centrifugal masses that are confined between a fixed plate and a moving plate. These centrifugal masses move outwards in a radial direction in the confined space when the vehicle operator increases the engine RPM. This outward movement of the centrifugal masses causes the movable plate to move axially and exert a force upon the stack of clutch and friction plates and allowing torque to be transmitted across them. This conventional construction accommodates springs linked to centrifugal masses that delay there outward movement and engagement of the clutch until a threshold engine RPM is reached. Another set of springs are also accommodated on the pressure plates to prevent sudden engagement and sticking of the clutch and friction plates causing judder vibrations.

[003] While the existing features facilitate smooth and gradual engagement of the centrifugal clutch leading to gradual increase in speed of the vehicle, they do not allow the vehicle operator to suddenly increase the speed/torque by suddenly increasing accelerator input. The centrifugal clutches thus cannot be used in high performance vehicles where quick acceleration from a standstill condition or a sudden increase in value of torque transmission is desired. Centrifugal clutches also don’t allow for quicker disengagement of the clutch. These problems are chiefly caused due the fact that the centrifugal masses experience inertia which prevents any immediate change in its postion until engine RPM has sufficiently increased or decreased.

[004] As manually overcoming the inertia of the centrifugal masses can be difficult at high engine RPMs, available mechanisms that can enable manual intervention in operation of the centrifugal clutches are not considered by engineers and vehicle designers as viable solutions to the described problem. As centrifugal clutches allow for smooth increase and decrease in torque transmission in normal operating conditions, they not only increase riding comfort but also make it easier for inexperienced riders to operate the motor vehicle. Engineers and vehicle designers are therefore very often faced with a dilemma while they are trying to deciding about whether or not they should provide a motor vehicle with a centrifugal clutch. Given the facts, there is exists a clear and unfulfilled need for centrifugal clutches that allow for easy manual intervention in its operation.

[005] The main object of the present invention is to provide a centrifugal clutch that can provide smooth engagement and disengagement in normal operating conditions.

[006] Another object of the present invention is to provide a centrifugal clutch that allows the user to have manual intervention during the operation of the clutch.

[007] Still another object of the present invention is to provide a centrifugal clutch that allows a motor vehicle to accelerate suddenly.
[008] Yet another object of the present invention is to provide a centrifugal clutch that can be easily disengaged manually even when engine RPM is still high.

Brief Description of Drawings

[009] 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

[0010] Figure 1 discloses perspective view of a fully assembled centrifugal multiplate wet clutch in accordance with the present invention.

[0011] Figure 2 shows the cut sectional view of centrifugal multiplate wet clutch as disclosed in Fig. 1 in accordance with the present invention.

[0012] Figure 3 shows an exploded view of a centrifugal multiplate wet clutch as per the present invention.

[0013] Figures 4a and 4b show perspective view and cut sectional view, respectively of a clutch housing of the centrifugal multiplate wet clutch as per the present invention.

[0014] Figures 5a and 5b show cut sectional view of centrifugal masses assembled within the clutch housing and perspective view of a centrifugal mass, respectively, as per the present invention.
[0015] Figure 6 shows centrifugal masses and the ramp plate as assembled within the clutch housing of the centrifugal multiplate wet clutch in accordance with the present invention.

[0016] Figure 7 shows the perspective view of ramp plate along with a moving sleeve as provided in the centrifugal multiplate wet clutch in accordance with the present invention.

[0017] Figure 8 shows centrifugal masses, the ramp plate and the fixed hub as assembled within the clutch housing of the centrifugal multiplate wet clutch as per the present invention.

Detailed Description of the Present Invention

[0018] Referring to Figures 2 and 3, a centrifugal multiplate wet clutch (100) for a two wheeled vehicle comprises of a clutch housing (5), a moving sleeve (10), a moving hub (15), a fixed hub (20), a ramp plate (25), a main spring (30), a plurality of hub opening springs (35), a plurality of clutch springs (40), a plurality of clutch plates (45), a plurality of friction plates (50), a plurality of centrifugal masses (55) with built in rollers (55R) and a bearing cup (60).

[0019] The clutch housing (5) has a central cylindrical opening (5CH) within which a bush (5BU) has been provided along one end and a bearing (5BE) has been provided along the other end to allow the clutch housing (5) to be rotatably mounted on an output shaft (5S). The clutch housing (5) is further fitted with a primary gear (5PG) along its outer periphery. The primary gear (5PG) is in contact with an engine gear (5EG) that is fixed on an engine output shaft to enable the engine gear (5EG) to receive and transmit a torque input from the engine. The clutch housing (5) is also provided with a plurality of profiled hollow internal projections (5HIP) that are formed at equal distance from central axis of the clutch housing (5) and at equal angles also measured along the central axis of the clutch housing (5) at its flat inner surface (5FS). One portion (55L) of the centrifugal masses (55) is positioned within these profiled hollow internal projections (5HIP). A cap (5CA) having a profile matching the profile of the profiled hollow internal projections (5HIP) is positioned within the profiled hollow internal projections (5HIP) so as to be located between the profiled hollow internal projections (5HIP) and the portion (55L) of the centrifugal masses (55). The profiled hollow internal projections (5HIP) enables the portion (55L) of the centrifugal masses (55) to articulate by an angle (?) within the profiled hollow internal projections (5HIP) (refer Figs. 4a, 4b, 5a and 5b).

[0020] The clutch housing (5) also has a plurality of hollow cylindrical projections (5HCP) alternately formed in-between the profiled hollow internal projections (5HIP) that are distributed at equal distance from central axis of the clutch housing (5) and at equal angles also measured along the central axis of the clutch housing (5) at its flat inner surface (5FS). The ramp plate (25) having extended arms (25EA) with holes (25EAH) at the end of each arm (25EA) is movably mounted in the hollow cylindrical projections (5HCP) with special bolts (25SB) having a smooth curved surface portion (25SBA). A spring (25S) is located concentrically with the special bolts (25SB) in between the head (25SBH) of the special bolt (25SB) and a rear surface of the extended arms (25EA) of the ramp plate (25). The ramp plate (25) has a central hole (25CH) that allows a moving sleeve (10) to pass through the ramp plate (25). A circlip (29) fitted at one end (10A) of the moving sleeve (10) restricts the degree of freedom of the ramp plate (25) axially in one direction. A main spring (30) is located on the moving sleeve (10) between the lower inside surface of the ramp plate (25) and a forward surface of an annular rib (10AR) given on the cylindrical portion of the moving sleeve (10). A thrust bearing (33TB) is placed on the rear surface of the annular rib (10AR) given on the cylindrical portion of the moving sleeve (10) (refer Figs 2, 6, 7 and 8).

[0021] The moving hub (15) has a central opening (15CH) that allows it to be mounted on cylindrical portion of the moving sleeve (10). The thrust bearing (33TB) is located between the rear surface of the annular rib (10AR) given on the cylindrical portion (15CP) of the moving sleeve (10) and the moving hub (15). The moving hub (15) has a cylindrical portion (15CP) with splines on its outer surface that allows the clutch plates (45) with internal projections (45P) to be axially movably mounted within them. A plurality of inclined solid projections (15TSP) extend from flat outer surface (15FOS) of the moving hub (15) and pass through with matching openings (20MHA) in the fixed hub (20). Another plurality of hollow cylindrical projections (15HCP) are alternatively positioned between the between the inclined solid projections (15TSP) pass through matching openings (20MHB) given in the fixed hub (20). Overlapping lubricating holes (10LH and 20LH) respectively provided on the cylindrical portions of the moving sleeve (10) and the fixed hub (20) allow lubrication fluid received within the fixed hub (20) through the output shaft (5S) to exit towards the main spring (30) and then into the clutch housing (5) (refer Figs. 1, 2 and 8).

[0022] The fixed hub (20) has an extended central cylindrical portion (20CCP) which allows the moving sleeve (10) to slide upon the extended central cylindrical portion (20CCP). A plurality of hub opening springs (35) are positioned between the moving hub (15) and the fixed hub (20) on the plurality of hollow cylindrical projections (15HCP). A plurality of clutch springs (40) are positioned between the flange surface (60FS) of the bearing cup (60) and the fixed hub (20) on the plurality of hollow cylindrical projections (15HCP). A plurality of bolts (63B) link the flange surface (60FS) of the bearing cup (60) with the hollow cylindrical projections (15HCP) of the moving hub (15). The bearing cup (60) can compress the clutch springs (40) and move axially within the fixed hub (20) up to a certain clearance distance (C) between the lower surface of the bearing cup (60) and an internal surface of the fixed hub (20). A bearing (60B) is mounted in the central portion (60CP) of the bearing cup (60) to accept an applied force move the bearing cup (60) axially within the fixed hub (20) (refer Fig. 2).

[0023] The clutch housing (5) has a cylindrical portion (5CP) with slots for mounting of friction plates (50) with matching outer projections (50P). The clutch plates (45) and the friction plates (50) alternatingly mounted on the moving hub (15) and clutch housing (5) respectively to form a stack. A conical spring (3S) and a washer (3W) is positioned between the moving hub (15) and the first clutch plate (45) forming the stack of clutch (45) and friction plates (50). A plurality of damping cushions (5DC) are provided on projections (5P) given on an outer flat surface of the clutch housing (5). The clutch housing (5) connects with an inner surface of the primary gear (5PG) through the plurality of damping cushions (5DC). A cover plate (1) holds the plurality of damping cushions (5DC) on the projections (5P) of the clutch housing (5) by means of rivets (1R) (refer Figs. 2 and 3).

[0024] When the engine of a vehicle is started / cranked, the centrifugal masses (55) begin to move and fly outwards in a motion that is guided by their interaction with the plurality of profiled hollow internal projections (5HIP). The built in rollers (55R) provided in the centrifugal masses (55) also begin to roll over the ramp plate (25) as the engine RPM increases. As the built in rollers (55R) of the centrifugal masses (55) start rolling over the ramp plate (25), the ramp plate (25) experiences an axial force which begins axially displacing the moving sleeve (10) together with the moving hub (15). The ramp plate (25) at low engine RPM does not compress the main spring (30) that is located on the moving sleeve (10) between the lower inside surface of the ramp plate (25) and a forward surface of an annular rib (10AR) given on the cylindrical portion of the moving sleeve (10). The thrust bearing (33TB) that is placed between the annular rib (10AR) given on the moving sleeve (10) and the moving hub (15) ensures that the moving sleeve (10) keeps sliding on the moving hub (15) without transmitting any significant amount of torque. As the engine RPM keeps on increasing the centrifugal masses (55) keep moving further outwards, causing the rollers (55R) housed therein to exert greater and greater axial force on the ramp plate (25).

[0025] As the clearance (C) between the moving hub (15) and the stack of clutch (45) and friction plate (50) is consumed due to axial movement of the ramp plate (25), the moving hub (15) along with the conical spring (3S) and the washer (3W) placed on the moving hub (15) begin pushing the stack of clutch (45) and friction plate (50) thereby initiating gradual increase in torque transfer from the clutch housing (5) to moving hub (15) and then to the fixed hub (20) of the clutch assembly. The clutch springs (40) located on the hollow cylindrical projections (15HCP) between the moving hub (15) and the fixed hub (20) ensure that the compression of the clutch (45) and friction plate (50) stack happens slowly thereby preventing any sudden complete engagement of the centrifugal multiplate wet clutch (100) under the action of the axial force being applied by the centrifugal masses (55).

[0026] At significantly higher engine RPM the clutch plates (45) and friction plates (50) forming the stack come in firm contact with each other thereby allowing complete torque transmission from the clutch housing (5) to the moving hub (15) and the fixed hub (20). A transmission/output shaft (5S) is linked via interlocking splines to the fixed hub (20). This arrangement therefore allows for all the torque that is transmitted from the engine gear (5EG) to the primary gear (5PG) and then via the clutch housing (5) and the clutch plates (45) and friction plate (50) stack to the moving (15) and fixed hub (20) to be transmitted to the transmission/output shaft (5S). As the engine RPM approaches a specific maximum limit, the main spring (30) that is located on the moving sleeve (10) between the ramp plate (25) and the annular rib (10AR) given on the moving sleeve (10) undergoes compression. This prevents an excessive axial force from the centrifugal masses (55) to be transmitted to the clutch plates (45) and friction plate (50) stack thereby preventing there destruction under the applied load.

[0027] When the vehicle operator/rider desires to manually operate the centrifugal multiplate wet clutch (100), they operate a mechanism conveniently provided on the motor vehicle to cause an axial force to be applied on the bearing cup (60) via a bearing (60B) situated within said bearing cup (60). This axial force compresses the clutch springs (40) and moves the bearing cup (60) axially. This axial movement of the bearing cup (60) is transmitted to the moving hub (15), which thereby causes the clutch plate (45) and friction plate (50) stack to move apart and stop transmitting torque. If the bearing cup (60) is displaced using the given mechanism when the engine RPM is low, the above disclosed centrifugal multiplate wet clutch (100) construction ensures that the ramp plate (25) is made to travel a greater axial distance before the clutch (45) and friction plate (50) stack starts getting compressed. This ensures initiation of torque transmission at a higher engine RPM thereby allowing the motor vehicle to receive a powerful start from a standstill condition.

[0028] When the engine RPM decreases the moving hub (15) moves axially under the influence of the hub opening springs (35). The ramp plate (25) is therefore also pushed axially. The ramp plate (25) also receives the force released from decompression of the spring (25S) mounted between its extended arms (25EA) and the special bolts (25SB). This allows for its smooth axial movement and allows it to push the centrifugal masses back to their initial low engine RPM postion.

[0029] The plurality of inclined solid projections (15TSP) extending from flat outer surface (15FOS) of the moving hub (15) and passing through matching openings (20MHA) in the fixed hub (20) facilitate both easy engagement and easy disengagement of the clutch plate (45) and friction plate (50) stack. When the engine RPM is increasing (i.e. the vehicle is accelerating), the moving hub (15) receives the torque and begins to transmit it to the fixed hub (20) through the clutch plate (45) and friction plate (50) stack and the inclined solid projections (15TSP). As the inclined solid projections (15TSP) are sloped with respect to the flat outer surface (15FOS) and in contact with the matching openings (20MHA) in the fixed hub (20), the forces setup during this condition cause the moving hub (15) to move closer to the fixed hub (20), thereby providing an assist for causing clutch engagement. Conversely, when the engine RPM is decreasing, the fixed hub (20) being rotationally fixed onto the output shaft (5S), continues to rotate with a decreasing velocity due to inertia. As the inclined solid projections (15TSP) are sloped with respect to the flat outer surface (15FOS) and in contact with the matching openings (20MHA) in the fixed hub (20), the forces setup during this condition cause the moving hub (15) to move further away from the fixed hub (20), thereby providing an assist for causing clutch disengagement.

[0030] The centrifugal multiplate wet clutch (100) with uniquely positioned centrifugal masses having rollers housed and inclined solid projections provided on the moving hub that are getting received in the fixed hub as disclosed and described above provides the following technical advantages contributing to technical advancement of the clutches.
- It allows for smooth engagement and disengagement in normal operating conditions.
- It allows for easy manual intervention by the rider to alter the operational state of the centrifugal clutch.
- It allows the rider to suddenly accelerate the motor vehicle from a standstill condition.
- It allows the rider to easily disengaged centrifugal clutch manually even when engine RPM is still high.

[0031] 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 embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein. ,CLAIMS:We Claim

1. A centrifugal multiplate wet clutch (100) for a vehicle comprising of a clutch housing (5), a moving sleeve (10), a moving hub (15), a fixed hub (20), a ramp plate (25), a main spring (30), a plurality of hub opening springs (35), a plurality of clutch springs (40), a plurality of clutch plates (45), a plurality of friction plates (50), a plurality of centrifugal masses (55) with rollers (55R) housed therein, a thrust bearing (33TB) and a bearing cup (60),
wherein,
- the clutch housing (5) is configured to have a plurality of profiled hollow internal projections (5HIP) and a plurality of hollow cylindrical projections (5HCP);
- the centrifugal masses (55) at its portion (55L) are positioned within the profiled hollow internal projections (5HIP) of the clutch housing (5);
- the ramp plate (25) has extended arms (25EA) with holes (25EAH) at the end of each arm (25EA) and is mounted in the hollow cylindrical projections (5HCP) of the clutch housing (5) with the bolts (25SB) having a smooth curved surface portion (25SBA);
- the thrust bearing (33TB) is placed on the rear surface of the annular rib (10AR) given on the cylindrical portion of the moving sleeve (10);
- the moving hub (15) is configured to have a plurality of inclined solid projections (15TSP) and a plurality of hollow cylindrical projections (15HCP); and
- said inclined solid projections (15TSP) extend from flat outer surface (15FOS) of the moving hub (15) and pass through matching openings (20MHA) in the fixed hub (20), and said hollow cylindrical projections (15HCP) are alternatively positioned between the inclined solid projections (15TSP) and pass through the matching openings (20MHB) given in the fixed hub (20).

2. The centrifugal multiplate wet clutch (100) as claimed in claim 1, wherein
- the profiled hollow internal projections (5HIP) are formed at equal distance from the central axis of the clutch housing (5) and are at equal angular distance measured along the central axis of the clutch housing (5) at its flat inner surface; and
- the hollow cylindrical projections (5HCP) are alternately formed in-between the profiled hollow internal projections (5HIP) and are placed at equal distance from central axis of the clutch housing (5) and at equal angular distance measured along the central axis of the clutch housing (5) at its flat inner surface (5FS).

3. The centrifugal multiplate wet clutch (100) as claimed in claim 2, wherein
- the clutch housing (5) has a central cylindrical opening (5CH) within which a bush (5BU) has been provided along one end, and a bearing (5BE) has been provided along the other end to allow the clutch housing (5) to be rotatably mounted on an output shaft (5S);
- said clutch housing (5) is fitted with a primary gear (5PG) along its outer periphery and said primary gear (5PG) is in contact with an engine gear (5EG) that is fixed on an engine output shaft to enable it to receive and transmit a torque input from the engine; and
- the clutch housing (5) has a cylindrical portion (5CP) with slots for mounting of friction plates (50) with matching outer projections (50P).

4. The centrifugal multiplate wet clutch (100) as claimed in claim 3, wherein
- the ramp plate (25) has a central hole (25CH) that allows a moving sleeve (10) to pass through the ramp plate (25); and a circlip (29) fitted at one end (10A) of the moving sleeve (10) restricts the degree of freedom of the ramp plate (25) axially in one direction;
- the main spring (30) is located on the moving sleeve (10) between the lower inside surface of the ramp plate (25) and a forward surface of an annular rib (10AR) given on the cylindrical portion of the moving sleeve (10);
- the moving hub (15) has a central opening (15CH) that allows it to be mounted on cylindrical portion of the moving sleeve (10); and said moving hub (15) has a cylindrical portion (15CP) with splines on its outer surface that allows the clutch plates (45) with internal projections (45P) to be axially movably mounted within them;
- the fixed hub (20) has an extended central cylindrical portion (20CCP) which receives and allows the moving sleeve (10) to slide upon the extended central cylindrical portion (20CCP);
- the plurality of clutch springs (40) are positioned between the flange surface (60FS) of the bearing cup (60) and the fixed hub (20) on the plurality of hollow cylindrical projections (15HCP); and
- a plurality of bolts (63B) link the flange surface (60FS) of the bearing cup (60) with the hollow cylindrical projections (15HCP) of the moving hub (15).

5. The centrifugal multiplate wet clutch (100) as claimed in claim 4, wherein,
- a plurality of damping cushions (5DC) are provided on projections (5P) given on an outer flat surface of the clutch housing (5) and said clutch housing (5) connects with an inner surface of the primary gear (5PG) through the plurality of damping cushions (5DC); and
- a cover plate (1) holds the plurality of damping cushions (5DC) on the projections (5P) of the clutch housing (5) by means of rivets (1R).

6. The centrifugal multiplate wet clutch (100) as claimed in claim 5, wherein,
- a spring (25S) is located concentrically with each of the bolts (25SB) in between the head (25SBH) of said bolt (25SB) and a rear surface of the extended arms (25EA) of the ramp plate (25);
- the moving sleeve (10) passing through the central hole (25CH) of the ramp plate (25) and having annular rib (10AR) supports the thrust bearing (33TB) that is located between the rear surface of the annular rib (10AR) given on the cylindrical portion of the moving sleeve (10) and the moving hub (15); and
- a plurality of hub opening springs (35) are positioned between the moving hub (15) and the fixed hub (20) on the plurality of hollow cylindrical projections (15HCP).

7. The centrifugal multiplate wet clutch (100) as claimed in claim 6, wherein,
- the bearing cup (60) compress the clutch springs (40) and move axially within the fixed hub (20) up to a certain clearance distance (C) between the lower surface of the bearing cup (60) and an internal surface of the fixed hub (20); and
- a bearing (60B) is mounted in the central portion (60CP) of said bearing cup (60) to accept an applied force and moves the bearing cup (60) axially within the fixed hub (20).

8. The centrifugal multiplate wet clutch (100) as claimed in claim 7, wherein,
- a cap (5CA) having a profile matching the profile of the profiled hollow internal projections (5HIP) is positioned within the profiled hollow internal projections (5HIP) so as to be located between the profiled hollow internal projections (5HIP) and the portion (55L) of the centrifugal masses (55); and
- the profiled hollow internal projections (5HIP) enables the portion (55L) of the centrifugal masses (55) to articulate by an angle (?) within the profiled hollow internal projections (5HIP).

9. The centrifugal multiplate wet clutch (100) as claimed in claim 8, wherein
- the clutch plates (45) and the friction plates (50) are alternatively mounted on the moving hub (15) and clutch housing (5) respectively to form a stack; and
- a conical spring (3S) and a washer (3W) is positioned between the moving hub (15) and the first clutch plate (45) forming the stack of clutch plates (45) and friction plates (50).

Dated this 19th day of May 2022

Sahastrarashmi Pund
Head – IPR
Endurance Technologies Ltd.

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