FIELD OF INVENTION
[0001] The present invention relates to an electric starter system for an internal
combustion engine and more particularly to a starter system implemented with reduced weight of rotating parts and reduced friction.
BACKGROUND OF INVENTION
[0002] In an internal combustion engine, the self-start mechanisms are of two
kinds: bendix drive and one-way clutch system. Bendix drives rely upon temporary engagement of bendix with the ring gear connected to crankshaft. Once the engine starts, the bendix is retracted back by spring force. On the other hand one-way clutch mechanisms rely upon unidirectional power transmissibility of one-way clutch or sprag clutch.^ Here, starter motor is disengaged from the engine due to the slip of one-way clutch once crankshaft of the engine starts revolving at a higher rpm (revolutions per minute) than the starter circuit.
[0003] As per the known-prior art, a bearing ring gear (needle bearing) is mounted
on crankcase snout formed by bearing insert that houses crankshaft bearing. Crankcase wall offset makes the snout a cantilever. This weakens the bearing support. In addition, since bearing loads are very high due to combustion, this design is potentially weak. In addition, there is very little room for increasing snout stiffness as the one-way clutch diameter becomes larger and hence difficulty while packaging. In addition, in such an art, -the one-way clutch is mounted rigidly on crank-web. Ring gear and spacer are integrated (operational during starting). Rotational inertia of crankshaft becomes higher because of

large one-way clutch .and as one-way clutch is fully balanced rotationally, the. corresponding weight on crank-web cannot be reduced. In addition, in such a design, one¬way clutch inner diameter is required to be larger than crankshaft bearing housing.
SUMMARY OF THE INVENTION
[0004] For internal combustion engines, it is proposed to implement a one-way
clutch for starter mechanism. The new mechanism is housed in the chamber created between the crankcase RH and cover oil pump. The one-way clutch is rigidly attached to face of the ring.gear and ring gear in turn is mounted on a static structural member, namely, cover oil pump unlike conventional mechanisms where the bearing will be seated on the rotating member, namely, crankshaft. The one-way clutch is guided with its inner diameter on a spacer that is press/spline fitted on crankshaft.
BRIEF DESCRIPTION OF DRAWINGS
Figure lillustrates a typical two-wheeler.
Figure 2illustrates sectional view of a typical engine of a two-wheeler.
Figure 3 illustrates the starting mechanism on right hand section of the engine.
Figure 4 illustrates a schema of the essential components of the proposed starting mechanism.
Figure 5 illustrates perspective view of the engine starting mechanism assembly.
Figure 6 Block diagram illustrating force transmission & interfacing of different components.

DETAILED DESCRIPTION OF THE INVENTION
[0005] The right hand side of crankcase is formed into two separate parts: first,
crankcase R split and second cover oil pump. Both parts are fastened together to form integral crankcase right hand side. One single, smaller casting i.e. cover oil pump houses oil pump and its drive gear on crankshaft and entire electric starter mechanism. The same casting provides mounting for magneto stator coil and pulser coil, starter motor, ring gear of starter mechanism, intermediate gear of starter mechanism, muffler body, and housing for fan and its cowl. This enables the crankcase R to be simpler and casting size reduces so that it can be manufactured with lower capacity machine. Crankcase R can be standardized across engine platforms by changing • only the cover oil pump thus increasing the modularity of the engine.
[0006] The one-way clutch is rigidly mounted on face of the ring gear, and the
ring gear in turn is mounted on a static structural member, namely, cover oil'pump through a bearing unlike conventional mechanisms where the bearing will be seated on the rotating member, namely, crankshaft. The one-way clutch is guided with its ID on a' spacer that is press/spline fitted on crankshaft.
[0007] After starting the engine, once the engine rpm becomes more than the rpm
being transferred by the starter motor, the one-way clutch starts slipping. However, unlike conventional starter mechanisms where the bearing rotates on crankshaft, the bearing housed inside the ring gear will be stationery. This helps reducing the overall engine friction. As the ring gear is mounted on cover oil pump, the shaft length requirement of the Crankshaft R reduces, thus making the layout compact.

[0008] As the ring gear bearing is mounted on cover oil pump, the bearing loads
created due to gear train are all transferred to the structure of the engine. Only pure torque transfer is " enabled from starter motor to crankshaft. This avoids fatigue load on crankshaft and eliminates bearing friction while engine is running. Rotational inertia of the crankshaft is reduced as spacer alone is mounted on the crankshaft.
[0009] Ring gear used in the current invention is a large external spur gear with
bearing ring gear press fitted on its ED. The assembly is rotatably mounted through ID of bearing onto snout of cover oil pump. Mounting holes are given on a pitch circle for
fastening one-way clutch on to it. Bearing ring gear is a ball/roller bearing housed inside_ ...
ring gear bore and mounted on cover oil pump snout. Cover oil pump is a casting cover mounted on Crankcase R, used to house oil pump, electric starter mechanisms while providing mounting support to many of the engine components namely, muffler body, stator & pulser coils of magneto, ring gear, starter motor, intermediate gear, housing fan/cowl etc.
[00010] One way clutch used, herein is a ball/roller/sprag type one way clutch
rigidly fastened axially on to ring gear and inner rollers guided on spacer of one way clutch, so that any rotation of the one way clutch in engine running direction will transmit the starting torque to spacer of one way clutch; and any relative rotation of spacer w.r.t one way clutch in engine running direction will make the clutch slip.
[00011] Gear oil pump drive cum spacer in the proposed one-way clutch starter
mechanism is a spur/helical gear and hard cylindrical steel spacer are integrally formed

axially into a single component and this is spline/tight fitted on crankshaft right arm. The gear part engages with 'gear oil pump driven' and the spacer portion engages/disengages with one-way clutch depending upon the crankshaft rpm with respect to ring gear. Starter motor is an electric motor used for starting the engine by providing initial torque to the crankshaft by means of starter mechanism and is mounted either on the cover oil pump or Son rthe. crankcase RH. Intermediate gear rotatably mounted on a pin 45, which is in turn ^mounted-on crankcase RH and cover oil pump with its axis parallel to the crankshaft. Intermediate gear is an intermediate compound gear that receives torque from starter motor, steps down the rpm and then transfers it to ring gear.
[00012] Crankshaft of the IC engine is a crankshaft with middle crank portion, L &
R shaft projections. Crankcase R of the IC engine is a casting cover that houses right portion of crankshaft complete and holds lubricating oil along with Crankcase L. Magneto stator & rotor are a dynamo mechanism to'charge battery while engine is running, stator of which is mounted on cover oil pump, and rotor .assembled on the crankshaft. A Pulser coil is used wherein an extension of magneto stator is used to sense pip (projection on magneto rotor).movement. Muffler body is part of exhaust system that houses silencer, with a mounting bracket welded on to it. Housing fan/cowl is a cowl part .that encloses cooling fan. A cooling fan is mounted on magneto rotor axially.
[00013] Crankshaft is housed inside Crankcase L & R assembly, as is the case with
any two-wheeler IC engine. Right arm of Crankshaft projects out of Crankcase R and passes through the starter chamber created by Crankcase R and Cover oil pump assembly and then the crankshaft R projects- out of Cover oil pump too. The crankshaft portion

inside the chamber is mounted coaxially with Gear oil pump drive (Spacer one-way clutch) rigidly with either tight fit or with the help of spline.
[00014] Inside the starter chamber, the gear part of Gear oil pump drive (GOPD) is
engaged with the oil pump gear and the smooth cylindrical portion is rotatably surmounted by a one-way clutch. One-way clutch in turn is clamped axially onto ring gear face so that the assembly rotates integrally. The ring gear along with a ball bearing (Bearing ring gear) is mounted on a snout on the cover oil pump coaxially formed along crankshaft axis. Through the hollow portion of the snout, the crankshaft projects out of .the cover oil. pump. To. summarize, the parts namely, Crankshaft rightjarm, Gear oil pump drive, One way clutch, Ring gear, Bearing ring gear, Snout on the Cover oil pump are all coaxial.
. [00015] An intermediate gear is mounted across Cover oil pump and crankcase R
with a pin intermediate gear, its axis parallel to crankshaft and with a fixed offset. The said gear meshes with ring gear and meshes with pinion of starter motor forming a compound gear train. The starter motor is in turn mounted on Crankcase R (or optionally mounted on cover oil pump also) with its axis parallel to those of intermediate gear and crankshaft.
[00016] Outside the starter chamber, a magneto rotor that in turn is assembled with
a cooling fan surmounts the crankshaft. Yet another snout is disposed outside the cover oil pump coaxially with the crankshaft supports magneto stator. Pulser coil is mounted on cover oil pump outer face and positioned with a fixed radial offset from the crankshaft

axis so that it can sense pip on the magneto rotor. During starting of the engine, the starter
motor torque is transferred to the intermediate gear. This is followed by gear intermediate
drives the ring gear with a fixed step-down ratio; the ring gear rotates smoothly over the
bearing ring gear along the snout axis. One-way clutch being fastened to ring gear also
rotates in engine rotation direction. As the engine, rotation direction is the engagement
direction for one way clutch plus the crankshaft being in rest at the start, the clutch drives
the spacer one way clutch which in turn drives the crankshaft. As the engine starts, the
crankshaft rpm exceeds that of the one-way clutch-ring gear assembly. This is followed
by slip of rollers over spacer one-way clutch (GOPD). This enables disengagement of
one-way clutch from the crankshaft. ■ -
[00017] Figure 1 shows a typical two-wheeled vehicle 1 with a rear wheel 2, engine 3, air filter 4, front wheel 5, floorboard 6, 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 "P' shows the front direction of the vehicle and direction of arrow "R" shows the rear direction of the vehicle. The engine 3 as disclosed in Figure 1 can be started either by the electrical starter mechanism or by the help of the kick starting mechanism.
[00018] Figure 2 illustrates cut section top view of the engine 3. It shows a
magneto rotor 21, cover oil pump 22, cylinder 23, crankshaft 24, magneto stator 25 and a tire26. A horizontal plane cutting the engine forms the engine cut section. The crankshaft 24 extends across the longitudinal width in the horizontal plane of the vehicle. The starter mechanism is installed in the right side of the crankshaft as seen from the rear to front

direction. Though the current engine as shown is a CVT type engine, the current invention is applicable to a non- CVT type engine as well.
[00019] Figure 3 illustrates the right hand side of the engine with the proposed
starter mechanism is more detail. Figure 3 shows crankshaft 24, starter motor 31, Crankcase Right 32, Spacer 33, One way clutch 34, Cover fan 35, Cover oil pump 22, Pin intermediate gear 36, Intermediate gear 37 and Ring gear 38. As explained previously Spacer 33, one way clutch 34, Cover oil pump 22, Intermediate gear 37 and Ring gear 38 rotate coaxially.
[00020] As shown in Figure 4, Figure 4 illustrates Crankshaft 24, Starter Motor 31,
Spacer 33, One way clutch 34, Intermediate gear 37, Oil pump 41, oil pump driving gear 42, oil pump driven gear 43, Bolt one way clutch to ri-ng gear 44, Pin intermediate gear 36. During starting of the engine, the starter motor 31 's torque is transferred to the • intermediate gear 37. This is followed by intermediate gear 37 drives the ring gear 38 with a fixed step-down ratio; the ring gear 38 rotates smoothly over the bearing ring gear along the snout axis. One-way clutch 34 being fastened to ring gear 38 also rotates in engine rotation direction.. As the engine rotation direction is the engagement direction for one way clutch 34, plus the crankshaft 24 being in rest at the start, the one way clutch 34 drives the spacer 33 which in turn drives the crankshaft 24. As the engine starts, the .crankshaft 24's rpm exceeds that of the one-way clutch-ring gear assembly. This is followed by slip of rollers over spacer 33. This enables disengagement of one-way clutch 34 from the crankshaft 24. At this instance, only spacer 33 rotates along with the crankshaft 24.

[00021] Figure 5 shows perspective view of the starter mechanism which includes-
the crankshaft 24, starter motor 31, one-way clutch 34, intermediate gear 37, ring gear 38 and oil pump 41. With the proposed starter mechanism and its arrangement, bearing of the ring gear 38 is mounted on cover oil pump snout (snout used exclusively for that purpose). Only starting load comes on to the snout; and not the combustion load. Spacer 33 is mounted rigidly on crankshaft 24. One-way clutch 34 and ring gear 38 are integrated (operational during starting), rotational inertia of crankshaft is lesser as only spacer 33 is mounted on crankshaft 24 also, due to which a smaller one-way clutch can be packaged very efficiently.
[00022] Figure 6 shows functional block diagram of the starter mechanism as
described above. As shown in the block diagram, the cover oil pump 22 is attached to the crankshaft 24; a ball bearing is mounted on cover oil pump 22 and interfaces with the ring gear 38; the ring gear 38 being attached to the one way clutch 34 which in turn mates with the said spacer 33 to transfer the rotation to the said crankshaft 24. The arrow mark indicates power transmission direction.

We claim:
1. A starter system for an internal combustion engine (3), the engine comprising:
a crankcase comprising of a crankcase right (crankcase RH) and crankcase left (crankcase LH);
a cover oil pump (22) fixed to the said crankcase RH;
a crankshaft (24), that can be rotated by either combustion of fuel in the cylinder of the said internal combustion engine (3) or by the said starter system;
a spacer (33) which is attached through spline fit or press fit mechanism to the said crankshaft (24);
a starter motor (31) which provides initial driving torque for rotating the said crankshaft (24), the said starter motor being mounted on the said crankcase RH;
an intermediate gear (37) disposed between the said cover oil pump and crankcase RH receiving driving torque from the said starter motor (31) and simultaneously driving a ring gear (38);
a ring gear (38) driven by the said intermediate gear (37) and driving a one way clutch (34) which further drives the said spacer (33);
wherein the said starter mechanism including oil pump (41) assembly being housed in a chamber created by said cover oil pump (22) and the said

crankcase RH and a ball bearing mounted on cover oil pump (22) supports the said ring gear (38) on the outer race which is further coupled to the said one way clutch (34) which mates with the said spacer (33) to transfer the rotation to the said crankshaft (24).
2. The starter system as claimed in Claim 1 wherein the said one way clutch (34) is mounted on the face of the said ring gear (38) and the said ring gear (38) is mounted on a static structural member through a bearing.
3. The starter system as claimed in Claim 1 wherein the said (33) spacer is integrated with the gear oil pump drive.
4. The starter system as claimed in Claim 1 wherein the said CCR supports the said starter motor (31), intermediate gear (37), muffler body, housing for fan, bearing ring gear (38), magneto stator coil and pulser coil, the bearing ring gear (38), magneto stator coil supported on two different snouts disposed coaxially opposite to each other.
5. The starter system as claimed in Claim 1 wherein the said bearing ring gear (38) is mounted on CCR that does not have the cover oil pump (22).