Title of Invention

OVERRUNNING CLUTCH FOR THE STARTER MOTOR OF AN I.C. ENGINE

Abstract

Overrunning slutch for the starter motor of an i.c. engine comprising a journal shaft, Primary rollers, auxiliary rollers, drive sleeve and roller springs, the drive sleeve consisting of a plurality of lobes, each containing a primary cam track and secondary cam track; two taper pathways formed per lobe between jounal shaft diameter and a cam track primary roller placed in the primary taper pathway, an auxiliary roller placed in the auxiliary taper pathway; roller springs each pressing against the primary roller along the primary taper pathway, so that the primary roller positions itself in a predetermined location.

Full Text

THE PATENTS ACT 1970 COMPLETE SPECIFICATION SECTION 10 OVERRUNNING CLUTCH FOR THE STARTER MOTOR OF AN l.C ENGINE LUCAS-TVS LIMITED, PADI, CHENNAI 600 050, TAMIL NADU, INDIA, AN INDIAN COMPANY. THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE NATURE OF THIS INVENTION AND. THE MANNER IN WHICH IT IS TO BE PERFORMED: Starter motor is an electromechanical device used in internal combustion engine applications. This device converts electrical energy from battery source to mechanical energy for cranking the engine and making it fire and continue to run. The power developed by the motor is transferred to ring gear of the engine through a pinion, which is driven by an over running roller clutch. The over running roller clutch performs two vital functions, viz. transferring power from starter motor to engine till the engine fires and after the engine fires, the mechanism in the over running roller clutch prevents the high speed of the pinion from being transferred to armature. The present starter motor has the following limitations: 1. In a given engine application, the space available for the starter motor restricts the size of the drive and hence the torque capacity. 2. The torque capacity of the overrunning clutch is restricted by the material properties of the components used. Use of high strength materials to take care of higher torque increases the cost of the starter motor. 3. The length of the roller, journal and drive sleeve influence the torque capacity and hence for higher torque capacity, bigger roller and related parts if provided increase the space requirements of the starter motor. If sufficient component size is not increased in drive assy to handle higher torque, the reliability of entire product is reduced. The overrunning clutch according to this invention comprises a journal shaft, primary rollers, auxiliary rollers, drive sleeve and roller springs, the drive sleeve consisting of a plurality of lobes each containing a primary cam track and secondary cam track; two taper pathways formed per lobef a primary roller placed in the primary taper pathway, an auxiliary roller placed in the auxiliary taper pathway; roller springs, each pressing against the primary roller along the primary taper pathway, so that the primary roller positions itself in a predetermined location. This invention will now be described with reference to the accompanying drawings which illustrate by way of example, and not by way of limitation, one of possible embodiments of the overrunning clutch proposed herein, Fig. 1 illustrating a sectional view of the drive assembly of the embodiment And Fig. 2 illustrating an exploded view of the said embodiment. In the overrunning clutch proposed herein an additional cam track and an auxiliary roller are provided for each lobe. The proposed overrunning roller clutch consists of journal shaft (4), primary rollers (1), auxiliary rollers (16), drive sleeve (2) and roller springs (10). The drive sleeve (2) consists of number of lobes (3) each containing a primary cam track (5) and secondary cam track (6). In this particular case, six lobes are illustrated. However it applies to different numbers of lobes as well. Two taper pathways are formed per lobe (3), between the journal diameter (7) and cam track (5,6), when the journal shaft (4) is assembled in the drive sleeve (2). The taper formed between primary cam track (5) and journal diameter (7) is termed as primary taper pathway (11). The taper formed between auxiliary cam track (6) and journal diameter (7) is termed as auxiliary taper pathway (12). In each lobe (3), one primary roller (1) is placed in the primary taper pathway (11). In addition, one auxiliary roller (16) is placed in the auxiliary taper pathway (12). For each primary roller (1), roller springs (10) are placed between the primary roller (1) and spring resting side (8) of buttress (9). Each roller spring (10) presses the primary roller (1) along the primary taper pathway (11), so that the primary roller (1) positions itself in a predetermined location. When the starter transmits power to the engine ring gear and cranks it, the following actions take place the proposed overrunning roller clutch. When the Journal shaft (4) is rotated along the converging direction of the taper pathway (13), then the primary roller (1) moves in this direction and comes in contact with the auxiliary roller (16). Due to this, the auxiliary roller (16) comes in contact with auxiliary cam track (6) and journal diameter (7). Now both primary roller (1) and auxiliary roller (16) share the load developed due to torque transmitted by the overrunning roller clutch. Since both the rollers (primary roller and the auxiliary roller) share this load, the compressive stress is less than that developed in the conventional overrunning roller clutch, for a given torque. Similar result is obtained when the drive sleeve (2) is rotated along the diverging direction of the taper pathway (14). When the engine drives the starter motor, the drive sleeve (2) and rollers (1 & 16) get unlocked and become independent of the journal shaft (4), when the journal shaft is rotated in the diverging direction of taper pathway (14). Similar result is obtained when the drive sleeve (2) is rotated along the converging direction of the taper pathway (13). In this condition, there is no torque transmission between drive sleeve (2) and journal shaft (4). This happens when the engine drives the starter Motor, that is, when the starter motor is still energized, even after the engine has fired. This makes the engine ring gear to drive the pinion of the starter at a very high speed. When the journal is rotated along the diverging taper pathway (14), both the auxiliary rollers (16) and primary rollers (1) are moved towards the same direction. A clearance is formed between the cam track (5 & 6) and rollers (1 & 16), which separate the drive sleeve (2) from journal shaft (4). No Torque transmission is possible in this condition. This prevents the excessive speed of the engine ring gear being transferred to the armature of the starter. The advantages of the invention proposed herein are: 1. Increased Torque transmitting ability of the proposed over-running clutch 2. Cost reduction 3. Weight Reduction - for the same torque transmitted, the new invention overrunning roller clutch is substantially less in weight. The terms and expressions herein are of description and not of limitation having regard to the scope and ambit of this invention.

Documents:

0988-che-2006 abstract-duplicate.pdf

0988-che-2006 claims-duplicate.pdf

0988-che-2006 description (complete)-duplicate.pdf

0988-che-2006 drawings-duplicate.pdf

988-che-2006- claims.pdf

988-che-2006- description-complete.pdf

988-che-2006- drawings.pdf

988-che-2006-abstract.pdf

988-che-2006-correspondence-others.pdf

988-che-2006-form 1.pdf

988-che-2006-form 18.pdf

988-che-2006-form 26.pdf