FIELD OF INVENTION
[0001] The present invention relates to a transmission system for a vehicle and more particularly to a modified pulley system on driven side of a CVT (Continuously Variable Transmission) type transmission system of a power-generating unit.
BACKGROUND OF INVENTION
[0002] An . internal combustion engine generates power and transmits it to transmission system, which further transmits the power to the wheel in a controlled way. There is a clutch system, which is present either between engine and transmission system or between transmission system and wheel. The clutch system enables the idling Of vehicle while engine is running. It can simply engage or disengage in order to transmit the power from one system to another. In scooters, IC engine transmits power to Continuously Variable Transmission (CVT) system, then this CVT transmits power to a centrifugal clutch and this clutch transmits power to wheel via final gear drive. A continuously variable power transmission system or device continuously varies the .power transmission from engine to wheel based on engine speed, engine torque, and wheel speed and wheel torque requirement.
[0003] This clutch is not appropriate for transferring significant torque or power because they can slip if loaded heavily clutch stall/tight rpm is not achieved. It involves friction and slipping between driving and driven parts, which results in loss of power. Some power is lost to rear wheel due to friction pads and shoes movement. Centrifugal clutches require more RPM before they engage. The RPM requirements can vary, so

sometimes the clutch does not engage (or disengage) when expected. This also means the friction clutch can be used for slowing down (as in a downshift) where the centrifugal might grab or might decide to free wheel. Clutch lining cost is significantly high.
SUMMARY OF THE INVENTION
[0004] In order to obviate the limitations and the problems associated with the present clutch system, the current invention relates to providing an alternative by eliminating the said centrifugal clutch from the vehicle. The function of the clutch would be taken care by the modified CVT driven pulley. Modified CVT driven pulley will have split surfaces / pulley, which enables vehicle idling during engine initial speed..
[0005] There are various advantages of modified CVT system over present clutch system. In the described modified CVT system, clutch function is taken care with improved transmission efficiency (no clutch slip), better fuel economy, lesser CVT driven assembly inertia, weight reduction, cost reduction, CVT driven pulley with less number of parts, higher reliability and improved vehicle response.
BRIEF DESCRIPTION OF DRAWINGS
Figure 1 illustrates a typical type two-wheeler.
Figure 2 illustrates the left side view of the two-wheeler.
Figure 3 illustrates sectional view of the internal combustion engine.

Figure 4 illustrates exploded view of the driving side and proposed driven side transmission system of the two-wheeler.
Figure 5 illustrates a typical type two-wheeler V belt position during idling/vehicle not in motion condition.
Figure 6 illustrates sectional view of the driving side and proposed driven side transmission system of the two-wheeler.
Figure 7 illustrates power transmission flow on the driving side and proposed driven side transmission system of the two-wheeler during engine idling/vehicle not in motion condition.
Figure 8 illustrates a typical type two-wheeler V belt position during vehicle in motion /running condition.
Figure 9 illustrates power transmission flow on the driving side and proposed driven side transmission system of the two-wheeler during vehicle in motion /running condition.
DETAILED DESCRIPTION OF THE INVENTION
[0006] The present invention replaces the conventional clutch system by a modified CVT system in which to a driven shaft, a first bearing is press fitted along with gear case, oil seal, and a first spacer. A second bearing is press fitted with a first split pulley and the said driven shaft. Further, a fixed pulley is assembled to the said driven shaft through a spline. A second spacer and a circlip are assembled on the driven shaft after

assembling the inner fixed pulley to avoid axial out movement of the said fixed pulley. A cylindrical part containing torque groove is welded with movable pulley, which also contains oil seals. A third bearing is press fitted with split pulley B. This assembly is press fitted with a cylindrical part containing torque groove. A pin roller assembly is inserted inside drive shaft and through torque groove. A first holder is press fitted with cylindrical part containing torque groove. Compression spring is assembled on the face of this first holder. A second holder is assembled against compression spring and butt-welded on driven shaft. A nut is provided to clamp the second holder axially.
[0007] During engine idling (speed'- ISOOrpm) and vehicle speed 0 kph, engine generates power and transmits it to drive pulley. Drive pulley transmits power to Belt. * Belt transmits power to the said first and second split pulleys namely pulleys A & B due to mechanical rotation. Split pulleys A & B rest on outer races of first bearing & second bearing respectively. Power from Split pulleys A & B is not transferred to driven shaft due to the said first bearing and the second bearing.
[0008] During Engine idling (engine speed > 2400rpm) and Vehicle speed > 0 kph, engine generates power and transmits it to drive pulley. Drive pulley transmits power to belt. Due to high engine speed, weight rollers will fly out.which in turn change the belt position in both drive and driven side. Belt transmits power to fixed pulley and movable pulley due to mechanical rotation. Fixed pulley and movable pulley are having positive drive i.e. spline and pin roller assembly respectively. Power from fixed pulley and movable pulley is transferred to driven shaft through spline, pin and roller assembly. The axial movements of drive and driven pulley assembly are controlled by weight

rollers and compression spring respectively, which is automatically mechanically decided by engine speed and the wheel torque requirement. The axial movement of pulley will decide the belt position in the radial direction. Hence, after the changeover of belt from split pulleys A & B to fixed and movable pulley, the system behaves similar to conventional mechanical CVT with added advantages as described.
[0009] Figure 1 shows a typical two-wheeled vehicle 1 with a rear wheel 2, engine 3, air filter 4, front wheel 5, floorboard6, utility box 7, side panel 9, front shock absorber 10, rear shock absorber 11, grab rail 12, tail lamp 13 and rider seat 14. The direction of arrow "F' shows the front direction of the vehicle and direction of arrow
"R" shows the rear direction of the vehicle. The power produced from the engine 3 is
<. transmitted to the wheels. Figure 2 shows engine 3, cylinder head 21 and rear wheel 2.
[00010] Figure 3 shows drive shaft 25, cylinder block 26, ramp plate 27, movable sheave of drive pulley 28, weight rollers 29, fixed sheave of drive pulley 30, CVT belt 31, driven pulley assembly 32, driven shaft 33 and wheel shaft 34, fixed sheave driven side 36 and a movable sheave driven side 37. Ramp plate 27 provides sliding surface to weight rollers 29 for varying CVT ratio. Weight rollers 29 slides between ramp plate 27 and movable sheave of driver pulley 28 for varying CVT ratio. The driven shaft 33 is supported on crankcase through a bearing (Not shown in Figure).
[00011] Figure 4 shows drive shaft 25, ramp plate 27, movable sheave of driver pulley 28, weight rollers (6 Nos) 29, fixed sheave of drive pulley 30, V- belt 31, CVT drive side 41, CVT driven side 42, spacer for fixed sheave of driver pulley 43, axial fan

44, spacer for ratchet nut 45, ratchet nut 46, nut 47, a first spring holder 50, a second spring holder 48, compression spring element 49, torque groove (cylindrical part) 51, torque groove follower pin 52, torque groove follower pin roller 53, a first bearing 54, split outer movable sheave of driven pulley 55, split inner movable sheave of driven pulley 56, split outer fixed sheave of driven pulley 57, split inner fixed sheave of driven pulley 58, a second oil seal 59, washer 60, circlip 61, a second bearing 62 and slot in driven shaft 63. The split outer fixed sheave of driven pulley 57 and split inner fixed sheave of driven pulley 58 together form the fixed sheave on the driven side. The split outer movable sheave of driven pulley 55 and split inner movable sheave of driven pulley 56 form the movable sheave on the driven side.
[00012] According to the first embodiment of the current invention, both the fixed and movable sheaves of the driven pulleys are split into atleast two sheaves, first outer sheave and another inner sheave. If the fixed and movable sheaves of the driven pulleys are split into more than two sheaves, the outer sheave would be the outermost sheave, and the other sheaves would be inner sheaves. Figure 5 shows the drive shaft 25, CVT Belt 31, driven Shaft 33, and split outer movable sheave of driven pulley 55.
. [00013] Figure 6 shows the drive shaft 25, ramp plate 27, movable sheave of drive pulley 28, weight rollers 29, fixed sheave of drive pulley 30, CVT belt 31, driven shaft 33, spacer for fixed sheave of driver pulley 43, axial fan 44, spacer for ratchet nut 45, ratchet nut 46, nut 47, the first spring holder 50, the second spring holder 48, compression spring element 49, torque groove (cylindrical part) 51, torque groove follower pin 52, torque groove follower pin roller 53, the first bearing 54, split outer

movable sheave of driven pulley 55, split inner movable sheave of driven pulley 56, split outer fixed sheave of driven pulley 57, split inner fixed sheave of driven pulley 58, a second oil seal 59, washer 60, circlip 61, the second bearing 62, a slot in driven shaft 63 and a spacer 64 for second bearing 62.
[00014] The spacer 64 is held at one end by the bearing holding the driven shaft ( with supported on crankcase) arid the second bearing 62 is butt on one side with the said spacer 64. Split outer fixed sheave of driven pulley 57 is press fitted on the second bearing 62. Split inner fixed sheave of driven pulley 58 is connected on driven shaft 33 by preferably spline connection. Other than spline connection, split inner fixed sheave of driven pulley 58 may be connected to driven shaft 33 by fixing, use of snap fit, welding, nut, thread or any.adhesive etc. 60. In this assembly till now, the inner diameter of split outer fixed sheave of driven pulley 57 is optimally greater than outer diameter of split inner fixed sheave of driven pulley 58 to accommodate the split inner fixed sheave of driven pulley 58. The washer 60 and circlip 61 are then assembled on the driven shaft 33. Torque groove (cylindrical part) 51, is rigidly connected to split inner movable sheave of driven pulley 56. This assembly (Torque groove (cylindrical part) 51 + split inner movable sheave of driven pulley 56) is fitted on driven shaft 33 with optimum clearance fit preferably by welding but not limited to welding and other than welding, spline connection , fixing by use of snap fit, welding, nut, thread adhesive etc. may also be used. The outer periphery of split inner movable sheave of driven pulley 56 and split inner fixed sheave of driven pulley 58 shall be chamfered to avoid

belt aberration while changing CVT ratio and more particularly during change over from idling to running or vice versa.
[00015] Four Nos of oil seals are assembled on Torque groove (cylindrical part) 51, two on each inner and outer sides to inhibit the grease leakage from the Torque groove (cylindrical part) 51 inside which enough grease is applied before insertion on the driven shaft 33. The grooves on torque groove (cylindrical part) 51 are designed and during assembly aligned in such a way so as it overlaps with the slot for torque groove follower pin 52 and the pin is tightened. Both the torque groove (cylindrical part) 51 are equipped with torque groove follower pin 52 which is assembled with two torque groove follower pin rollers 53 assembled on a slot in driven shaft 63 through torque groove (cylindrical part) 51. Splitted outer movable sheave of driven pulley 55 is press fitted on first bearing 54. After assembly of split outer movable sheave of driven pulley 55 is press fitted on first bearing 54, this combined assembly (split outer movable sheave of driven pulley 55 + first bearing 54) is fitted on torque groove (cylindrical part) 51 with an optimum clearance. Torque groove with pin roller assembly acts as mechanical torque sensor and actuator for sensing wheel torque requirement, rotational speed and CVT ratio. First spring holder 50 has optimum clearance fit on torque groove (cylindrical part) 51 and is axial butt on first bearing 54.
[00016] Compression spring element 49 on one end is butt on the first spring holder 50 and another on a second spring holder 48. The second spring holder 48 is butt on a . step provided on driven shaft 33 against the compression spring element 49. Lock nut 47 is used for locking the second spring holder 48 axially and the whole system

thereby. Spring element 49 provides enough calculated force to the movable sheave assembly on the driven shaft such that the belt lies only on the faces of outer sheaves to attain idling in absence of enough engine torque and rpm. The sequence of assembly as described in this paragraph also illustrates the manner in which the various elements of the current embodiment in the invention are assembled.
[00017] The surfaces of the fixed and movable sheaves of driven pulley on which the belt resides are called as faces of the respective sheaves. The outer periphery of split inner movable sheave of driven pulley 56 and split inner fixed sheave of driven pulley 58 shall be chamfered to avoid belt abrasion while changing CVT ratio and more particularly during change over from idling to running or vice versa.
[00018] The faces of split outer fixed sheave of driven pulley 57 and split inner fixed sheave of driven pulley 58 must be aligned without any step formation for smooth transition of belt from the outer to inner face of fixed sheaves and vice versa. The faces of split outer movable sheave of driven pulley 55 and split inner movable sheave of driven pulley 56 must be aligned without any step formation for smooth transition of belt from the outer to inner face of fixed sheaves and vice versa. During vehicle deceleration, the CVT belt 31 starts moving radially outwards from the inner sheaves towards the outer sheaves. If engine is put to idling condition, during vehicle moving on down gradient, the CVT belt 31 remains on the outer sheaves.
[00019] Figure 7 shows the Power transmission from the drive shaft 25 to the driving pulley and further to the driven side through the belt 31 during vehicle idling condition.

The dashed arrows illustrate the power transmission from one part to another part of the driving side and driven side. Power transmission arrow 71 illustrates the power transmission from drive shaft 25, which further is bifurcated towards the ramp plate 27 and fixed sheave of driven pulley 30. Power transmission arrow 72 illustrates the power transmission from drive shaft 25 to the ramp plate 27 and the power transmission arrow 73 illustrates the power transmission from ramp plate 27 to movable sheave 28 of the drive pulley via the weight rollers 29. Power transmission arrow 74 illustrates the power transmission from drive shaft 25 to fixed sheave of drive pulley 30. Power transmission arrow 75 illustrates the power transmission from fixed sheave of drive pulley 30 to CVT Belt 31. Power transmission arrow 76 illustrates the power transmission from movable sheave 30 of drive pulley to CVT Belt 31. Power transmission arrow 70 illustrates the power transmission from driving pulley and to the driven side through the CVT Belt 31.
[00020] Furthermore," Figure 7 shows the power transmission from the CVT belt 31 to the driven shaft 33 through the proposed clutch-less mechanism 32 (Shown in Figure 3) during vehicle idling condition, when vehicle is not under motion. In this idling condition, the CVT Belt 31 lays in-between the split outer movable sheave of driven pulley 55 and split outer fixed sheave of driven pulley 57. Power transmission arrow 77 illustrates the power transmission from CVT Belt 31 to the Splitted outer fixed sheave of driven pulley 57. Power transmission arrow 78 illustrates the power transmission from CVT Belt 31 to the Split outer movable sheave of driven pulley 55. Power transmission arrow 79 illustrates the power transmission from Splitted outer fixed

sheave of driven pulley 57 to second bearing 62. Power transmission arrow 81 illustrates the power transmission from Split outer movable sheave of driven pulley 55 to the first bearing 54.
[00021] Figure 8 shows the drive shaft 25, CVT belt 31, driven shaft 33, and split outer movable sheave, of driven pulley 55 during vehicle running condition.
[00022] Figure 9 shows the power transmission (90) from the drive shaft 25 to the driving pulley and further to the driven side through the belt 31 during vehicle running condition. The dashed arrows illustrate the power transmission from one part to another part of the driving side and driven side during vehicle running condition. Power transmission arrow 71 illustrates the power transmission from drive shaft 25, which further is bifurcated towards the ramp plate 27 and fixed sheave of driven pulley 30. Power transmission arrow 72 illustrates the power transmission from drive shaft 25 to the ramp plate 27 and the power transmission arrow. 73 illustrates the power transmission from ramp plate 27 to movable sheave 28.of the drive pulley via the weight rollers 29. Power transmission arrow 74 illustrates the power transmission from drive shaft 25 to fixed sheave of drive pulley 30. Power transmission arrow 75 illustrates the power transmission from fixed sheave of drive pulley 30 to CVT Belt 31. Power transmission arrow 76 illustrates the power transmission from movable sheave 30 of drive pulley to CVT Belt 31. Power transmission arrow 70 illustrates the power transmission from driving pulley and to the driven side through the CVT Belt 31.

[00023] Furthermore, Figure 9 shows the power transmission from the CVT belt 31 to the driven shaft 33 through the proposed clutch-less mechanism 32 (Shown in Figure 3) during vehicle running condition. Under the vehicle running condition, the CVT Belt 31 lays in-between the split inner movable sheave of driven pulley 56 and split inner fixed sheave of driven pulley 58. Power transmission arrow 91 illustrates the power transmission from CVT Belt 31 to the split inner fixed sheave of driven pulley 58. Power transmission arrow 92 illustrates the power transmission from CVT Belt 31 to
the split inner movable sheave of driven pulley 56. Power transmission arrow 93
* illustrates the power transmission from split inner fixed sheave of driven pulley 58 to
driven shaft 33. Power transmission arrow 94 illustrates the power transmission from
split inner movable sheave of driven pulley 56 to torque groove (cylindrical part) 51.
Power transmission arrow 95 illustrates the power transmission from torque groove
(cylindrical part) 51 to torque groove follower pin 52. Power transmission arrow 96
illustrates the power transmission from torque groove follower pin 52 to the driven
shaft 33.

We claim:
1. A transmission system for a power generating unit (3) comprising of:
a driving side of the transmission which further essentially comprises of a drive shaft (25) accommodating a ramp plate (27), a movable sheave of drive pulley (28), weight rollers (29), fixed sheave of drive pulley (30) and a CVT Belt (31) in between the said movable sheave of drive pulley (28) and the said fixed sheave of drive pulley (30);
a driven side essentially comprising of a driven shaft (33); a pulley with fixed sheave driven side (36), and a movable sheave driven side (37);
wherein the said fixed sheave (36) is further split into atleast two sheaves namely an inner sheave of the fixed sheave (58) and outer sheave of the fixed sheave (57)
. and
the said movable sheave (37) is further split into atleast two sheaves namely inner sheave of the movable sheave (56) and outer sheave of the movable sheave (55).
2. A transmission system for a power generating unit (3) comprising of:
a driving side which essentially comprises of a drive shaft (25) accommodating a ramp plate (27), a movable sheave of drive pulley (28), a plurality of weight rollers (29), a fixed sheave of drive pulley (30) and a CVT Belt (31) in between the said movable sheave of drive pulley (28) and the said fixed sheave of drive pulley (30);
a driven side essentially comprising of a driven shaft (33); a pulley with fixed sheave driven side (36), and a movable sheave driven side (37);
V

wherein the said fixed sheave (36) is further split into atleast two sheaves namely an inner sheave of the fixed sheave (58) and outer sheave of the fixed sheave (57) and the said movable sheave (37) is further split into atleast two sheaves namely inner sheave of the movable sheave (56) and outer sheave of the movable sheave (55).
characterized in that:
the said CVT belt (31); on driving side resides and travels in between the said movable sheave of driving pulley (28) and the fixed sheave of driving pulley (30); and on the said driven side is held and travels in between the faces of outer sheaves (57) of the said fixed driven pulley (36) and the outer sheave (55) of the said movable pulley (37) under vehicle idling condition;
and
the said CVT belt (31) on driving side is located and travels in between the said movable sheave of driving pulley (28) and the fixed sheave of driving pulley (30); and on the said driven side is held and travels in between the faces of inner sheaves (58) of the said fixed driven pulley (36) and the inner sheave (56) of the said movable pulley (37) under vehicle moving condition.
3. The transmission system for a power-generating unit (3) as claimed in Claiml or
- Claim 2 wherein an spring element (49) with a pre-determined spring constant
provides enough force to the movable sheave assembly (55, 56) on the driven shaft such that the belt resides only on the faces of outer sheaves to attain idling condition in absence of enough engine power and rpm.
4. The transmission system for a power-generating unit (3) as claimed in Claiml or
Claim 2 wherein the faces of split outer fixed sheave of driven pulley (57) and split
inner fixed sheave of driven pulley (58) are aligned without any step formation.

5. The transmission system for a power-generating unit (3) as claimed in Claim! or Claim 2 wherein faces of split outer movable sheave of driven pulley (55) and split inner movable sheave of driven pulley (56) are aligned without any step formation.
6. The transmission system for a power-generating unit (3) as claimed in Claiml or Claim 2 wherein any of the said inner and outer sheaves of the said driving pulley (28,30); driven pulley (36,37) or any intermediate pulley have atleast one sheave split into atleast two concentric sheaves.