This invention relates to an engine starting system, more particularly, though not exclusively, to a starting system for i.e. engines, such as, i.e. engines for automobiles.

The known engine starting system consists of an electric motor, an over running clutch and a pinion mounted on the motor armature shaft. The motor armature shaft has external helical splines and the said clutch has internal helical splines.

In the known system, the pinion has straight teeth, which in turn engage with mating straight teeth on the ring gear of the engine.

The known starting system also consists of a solenoid switch for the purpose of moving the clutch and the pinion on the rotating armature shaft in the direction of the engine ring gear; and also for the purpose of turning on and off the power supply to the motor.

In the known starting system, when the engine, on being started, attains a speed exceeding that of the starter motor, the disengagement of pinion teeth from the ring gear teeth, is accomplished by the solenoid switch, the over running clutch, the external helical splines of the armature shaft and the internal helical splines of the over running clutch..

This invention proposes an engne starting system which, (i) ensures smooth engagement and disengagement of the pinion teeth and ring gear teeth, easier than that of the known starting system; (ii) during cranking of the engine, reduces noise when compared to the known system; (iii) increases torque transmission capability of the pinion and ring gear to an extent beyond that of the known system.

Other advantages of this invention will be apparent from its further description to follow:

The engine starting system, according to this invention, comprises a motor; a solenoid switch; and an over running clutch coupled to a pinion, said clutch being powered by the motor to cause the pinion to engage with, and disengage from, a ring gear provided for the engine, characterized in that the pinion and the ring gear have mating helical teeth, while the armature shaft of the motor has external straight splines mating with internal straight splines in the over running clutch sleeve.

In one of the embodiments of this invention, a planetary gear reduction box is provided between the motor and the over running clutch.

The accompanying drawings illustrate

In Fig.1, a known engine starting system

In Fig. 2, one of possible embodiments of this invention

In Fig.3, a known engine starting system with planetary gear reduction box

In Fig.4, another of possible embodiments of this invention with planetary gear reduction box.

Referring to Fig. 1, the known starting system consists of a pinion P1 with straight teeth, exemplified by involute teeth, for engaging with, and disengaging from, a ring gear R1, also with similar teeth. When the motor M1 is energized, the solenoid switch A1, external helical splines on the armature shaft S1 and internal mating helical splines of the over running clutch C1 cause the pinion P1 to engage with the ring gear R1 to drive the said ring gear for starting the engine.

When the engine is started and its speed exceeds that of the motor, the disengagement of pinion P1 from the ring gear R1 is accomplished by the solenoid switch A1, over running clutch C1, the external helical splines on the armature shaft S1 and internal mating helical splines of the over running clutch C1.

Referring to Fig. 2, an embodiment of the proposed starting system consists of a pinion P2 with helical teeth for engaging with, and disengaging from, a ring gear R2 also with mating helical teeth. Motor M2 has its armature shaft S2 with external straight splines , and the over running clutch C 2 has mating internal straight splines.

When the motor M2 is energized, the clutch C2 along with solenoid switch A2 causes the pinion P2 to engage with the ring gear R2 to drive the said ring gear for starting the engine. When the engine is started and when its speed exceeds that of the motor, the disengagement of pinion P2 from the ring gear R2 is accomplished by the solenoid switch A2, over running clutch C2, helical teeth on the pinion P2 and the mating helical teeth on ring gear R2.

In this embodiment of the invention, the engagement and disengagement of the pinion and ring gear are rendered easier than that of the known starting system; the noise produced by such engagement and disengagement is reduced; the torque transmission capability of the pinion teeth and mating ring gear teeth is increased beyond that of the known starting system. By reason of the aforementioned construction, the life of the ring gear is enhanced, so that replacement costs are minimized for the end user.

This invention is equally applicable to a case where the starting system is provided with gear reduction, such as, a planetary gear reduction box between the motor and the over running clutch.

Referring to Fig. 3, in the known starting system provided with a planetary gear reduction box, the straight teeth on the pinion P3 engage with, and disengage from, the mating straight teeth of the ring gear R3. The external helical splines on the output shaft S3 of the motor armature get the drive from motor M3 in accordance with the planetary gear ratio and transmit the drive to the over running clutch C3 through the internal mating helical splines in the said over running clutch. The output shaft of the .planetary gear box and the sleeve of the over running clutch have, respectively, mating external and internal helical splines. When the motor is energized , the over running clutch C3 along with solenoid switch A3 , cause the pinion P3 to engage with the ring gear R3 to drive the ring gear for starting the engine.

When the engine is started and its speed exceeds that of the motor, the disengagement of pinion P3 from the ring gear R3 is accomplished by the solenoid switch A3, over running clutch C3, external helical splines on motor armature output shaft S3 and internal mating helical splines in the over running clutch C3.

Referring to Fig. 4, another embodiment of the proposed starting system consists of a pinion P4 with helical teeth for engaging with, and disengaging from, a ring gear R4 also with mating helical teeth. The external straight splines on the motor output shaft S4 get the drive from motor M4 in accordance with the planetary gear ratio and transmit the drive to the over running clutch C4 through internal straight splines in the said clutch.

The output shaft of the .planetary gear box and the sleeve of the over running clutch have, respectively mating external and internal straight splines. When the motor is energized the over running clutch C4 along with solenoid switch A4 , causes the pinion P4 to engage with the ring gear R4 to drive the said ring gear for starting the engine.

When the engine is started and its speed exceeds that of the motor, the disengagement of pinion P4 from the ring gear R4 is accomplished by the solenoid switch A4, over running clutch C4, the helical teeth on the pinion P4 and the mating helical teeth on ring gear R4.

It will be appreciated that various other embodiments of this invention are possible without departing from the scope and ambit of this invention.

WE CLAIM:

1. An engine starting system comprising a motor; a solenoid switch; and an over running clutch coupled to a pinion, said clutch being powered by the motor to cause the pinion to engage with, and disengage from, a ring gear provided for the engine, characterized in that the pinion and the ring gear have mating helical teeth, while the
armature shaft of the motor has external straight splines mating with internal straight splines in the over running clutch sleeve.

2. An engine starting system as claimed in Claim 1 wherein a planetary gear reduction box is provided between the motor and the over running clutch.

3.An engine starting system as claimed in claim 2 wherein the output shaft of the planetary gear box and the sleeve of the over running clutch have, respectively, mating external and internal straight splines

4. An engine starting system substantially as herein described with reference to, and as illustrated in. Figs. 2 and 4 of the accompanying drawings.