CENTRIFUGAL STARTING SYSTEM

FIELD OF INVENTION

The present invention relates to a "centrifugal starting system" and more particularly to a starting system mechanism that transfers power from the starter motor to the crankshaft of a four stroke internal combustion engine.

BACKGROUND OF INVENTION

Internal combustion engines are typically cranked by a kick starter or an electric starter. The kick starting system comprises of a kick pedal, which the rider must forcibly move over a partial rotation path, the kick pedal being connected to the kick shaft, which is connected through a clutch and gearing or chain mechanism to the crankshaft. When the rider forces the kick pedal downward, the crankshaft is rotated and the piston is moved which starts the engine. Forcing the kick pedal downwards requires a minimum amount of strength and some riders, for example aged persons or female riders, may face difficulty in starting the motorcycle. Further, there is likelihood of recoil of kick pedal, that is, forceful driving back of the kick pedal in the opposite direction of the kicking motion, which might lead to injuries to the rider. To circumvent the drawbacks of the kick starting system, the electric starting system came to be used in the art.

The electric starting system comprises a battery, an ignition system, a starter motor and a mechanism to transfer power from the starter motor to the crankshaft. The said mechanism may be a bendix drive or a one-way clutch. In case of a bendix drive, the rpm of the starter motor is usually more so as to engage the bendix drive to the ring gear connected to crankshaft. In case the battery voltage is low, the motor may not rotate with the required rpm and therefore the bendix drive might not get engaged and the engine cannot be cranked. In case of system provided with one way clutch, there will always be contact between the different rotating components. Hence due to wear and tear, the life of the moving parts gets shortened thereby increasing the maintenance cost. Therefore to obviate defects in the prior art, there is a requirement for an improved starting system, which addresses the above-mentioned drawbacks of using a bendix drive or a one way clutch for power transmission in a conventional starting system.

SUMMARY OF INVENTION

The present invention has been made in light of the foregoing problems and it is the objective of the present invention to eliminate the use of a bendix drive or one way clutch, for power transmission from the starter motor to the crank shaft in a starting system for an internal combustion engine. The centrifugal starting system for an internal combustion engine as per the present invention comprises of a toothed base plate, a lock tooth, a spring, a pin and tooth retainer, a slotted drum, a starter motor, a base plate, a crankshaft, a retainer plate, an inner ring, and an outer ring. The toothed base plate consists of a pin on which the lock tooth is pivoted. The lock tooth is free to rotate about the pivot axis. However, the inner ring welded to the base plate arrests the rotation of the lock tooth after a certain degree of rotation. The lock tooth is spring loaded. One end of the spring is connected to the slot provided on the lock tooth and the other end is connected to the outer ring which is in turn welded to the toothed base plate. The toothed base plate is rotatably mounted on the base plate. The slotted drum is mounted on the crankshaft in such a way that it rotates with the crankshaft. The portion of the toothed base plate, which consists of the lock tooth and the spring, is placed just inside the slotted drum such that the toothed base plate and the slotted drum are coaxial. The teeth of the toothed base plate meshes with the starter motor pinion.

When the starter motor rotates, the starter motor pinion rotates the toothed base plate. At a certain rpm of the starter motor, centrifugal force causes the lock tooth to overcome the spring force and the lock tooth rotates about its pivotal axis to a certain degree of rotation until its rotation is arrested by the inner ring. At this position, the tip of the lock tooth gets engaged to a slot on the slotted drum. This tends to rotate the slotted drum, which rotates the crankshaft, which in turn cranks the engine. In the present invention, since the use of bendix drive or one way clutch has been avoided, there is considerable reduction in weight of the system. Further, manufacturing cost is also substantially reduced and the engine can be cranked even when the battery level is minimum. The centrifugal starting system as per the present invention, with minimum modifications, can be used to crank the engine in both clockwise and anti-clockwise direction.
These and other features, aspects, and advantages of the present invention will be better understood with reference to the following description, the appended claims and the accompanying drawings.' This summary is not intended to limit the scope of the claimed subject matter.

BRIEF DESCRIPTION OF DRAWINGS

The above and other features, aspects, and advantages of the present invention are further illustrated by the accompanying drawings. The drawings are given by way of illustration only and are not limitative of the present invention. A brief description of the drawings is as follows:

Figure 1 shows the side view of a conventional two wheeled automotive vehicle.

Figure 2 is a sectional view of the centrifugal starting system as per the present invention.

Figure 3 is an exploded view of the centrifugal starting system as per the present invention.

Figure 4 is a side view of the toothed base plate of the centrifugal starting system as per the present invention.

DETAILED DESCRIPTION OF INVENTION

A conventional two wheeled automotive vehicle as illustrated in Figure 1, includes an internal combustion engine 41, a front wheel 25, a rear wheel 27, a body frame 19 and a fuel tank 56. Body frame 19 includes a head pipe 12, a main tube 17, a down tube 22, and seat rails 18. The head pipe 12 is provided at the front end of body frame 19 to support a steering shaft 11 disposed within the head pipe 12. The upper and lower ends of the steering shaft 11 are fixed to an upper bracket 13 and a lower bracket 14 respectively. Upper bracket 13 and lower bracket 14 retain front suspensions 16 that supports front wheel 25. The front wheel 25 is connected at the lower end of the front fork 16, and the upper portion of the front wheel 25 is covered by a front fender 54 mounted to the lower portion of the front fork 16. A handlebar 15 is fixed to upper bracket 13 and can rotate to both sides. A head light 36 is arranged on an upper portion of the front fork 16. Down tube 22 is located in front of the internal combustion engine 41 and stretches slantingly downward from head pipe 12. A bracket 55 is provided at the lower end of down tube 22 for supporting the internal combustion engine 41. Main tube 17 is located above the internal combustion engine 41 and stretches rearward from head pipe 12 and connects the rear of the internal combustion engine 41. A vertical pipe 28 is joined to the rear end of main tube 17 and stretches downward from the point where the main tube 17 joins the seat rails 18. Seat rails 18 are joined to main tube 17 and stretch rearward to support a seat 57 disposed above seat rails 18. A side stand 58 is arranged towards the lower portion of the internal combustion engine 41. Left and right rear arm bracket portions support a rear arm 26 to swing vertically, and a rear wheel 27 is connected to rear end of the rear arm 26. A rear wheel suspension 34 is arranged between rear arms 26. A tail light unit 64 is disposed on the rear cover 61. A pillion footrest 31 is connected to the vertical pipe 28. A grab rail 62 is also provided on the rear of the seat rails 18. Rear wheel 27 is arranged below seat and rotates by the driving force of the internal combustion engine 41 transmitted through the transmission system. A cranking or a starting system is also provided along with a starter motor to crank the internal combustion engine 41.

The centrifugal starting system for an internal combustion engine as per the present invention has been illustrated in Figure 2, Figure 3 and Figure 4. It comprises of a starter motor 111, a toothed base plate 102 rotatably mounted on a base plate 103, a lock tooth 100 which is pivoted to the toothed base plate 102 by way of a pin 101 such that the lock tooth 100 is free to rotate about the pivot axis, an inner ring 104 welded to the base plate 103 such that it prevents the rotation of the lock tooth 100 beyond a certain degree, an outer ring 105 welded to the toothed base plate 102, a spring 112 connected to the lock tooth 100 at its one end and the other end connected to the outer ring 105, a pin and tooth retainer 109 which prevents the pin 101 and lock tooth 100 from changing its position on the toothed base plate 102, and a slotted drum 108 mounted on a crankshaft 110 such that it rotates with the crankshaft 110. The starter motor 111 has a pinion to which the teeth of the toothed base plate 102 is meshed. The side of the toothed base plate 102 having the lock tooth 100 and the spring 112, is arranged in this way that it faces in the direction of the slotted drum 108 and the same is placed just inside the slotted drum 108 such that the toothed base plate 102 and the slotted drum 108 is coaxial.

When the starter motor 111 rotates, the toothed base plate 102, which is meshed to the starter motor pinion, rotates. At a certain rpm of the starter motor 111, centrifugal force on the lock tooth 100 overcomes the spring force on the lock tooth 100, which leads to its rotation. The lock tooth 100 rotates about its pivotal axis. The lock tooth is stopped from rotating beyond a certain degree by the inner ring 104. At this position, the tip of the lock tooth 100 gets engaged to a slot of the slotted drum 108. This leads to the rotation of the slotted drum 108, which in turn rotates the crankshaft 110 resulting in cranking of the engine. Once the engine starts and the rpm of the engine exceeds that of the starter mechanism, the rear end of the engaged slot of the slotted drum 108 hits the rear side of the lock tooth 100 and pushes it to its original position (static position). Moreover, as the starter motor 111 decelerates, the spring force becomes prominent compared to the centrifugal force and this pulls back the lock tooth 100 to its original position. This ensures that there is no contact between the engine and the centrifugal starter mechanism when the engine is running. In the centrifugal starter system as per the present invention, single or multiple lock tooth arrangements can be used for engaging with the slotted drum. The weight and manufacturing cost of the starting system has been substantially reduced since the use of bendix drive/one-way clutch is avoided. Further, the arrangement as per the present invention enables cranking of the engine even at low battery levels.

The foregoing description is a specific embodiment of the present invention and has been described for the purpose of illustration only. Persons skilled in the art may practice numerous alterations and modifications of the present invention without departing from its spirit and scope. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.

We claim:

1. A centrifugal starting system for an internal combustion engine comprising,

a toothed base plate 102 rotatably mounted on a base plate 103;

a lock tooth 100 pivoted on a pin 101 on the toothed base plate 102, such that the lock tooth 100 is free to rotate about the pivot axis;

an inner ring 104 welded to the base plate 103 such that rotation of the lock tooth 100 beyond a threshold is prevented by the said inner ring 104;

an outer ring 105 welded to the toothed base plate 102;

a spring 112 whose one end is secured to the lock tooth 100 and the other end is secured to the outer ring 105;

a pin and tooth retainer 109 which prevents displacement of the lock tooth 100 and the pin 101;

a slotted drum 108 having at least one slot, the said slotted drum 108 mounted on a crankshaft 110 such that it rotates with the crankshaft 110; and

a starter motor 111 which comprises of a pinion to which the teeth of the toothed base plate 102 is meshed;

wherein the tip of the lock tooth 100 engages with a slot on the slotted drum 108 when the centrifugal force on the lock tooth 100 exceeds the spring force on it.

2. The centrifugal starting system for an internal combustion engine as claimed in claim 1, wherein the side of the toothed base plate 102 having the lock tooth 100 and the spring 112, is disposed in such a manner that it faces in the direction of the slotted drum 108.

3. The centrifugal starting system for an internal combustion engine as claimed in claim 1, wherein the portion of the toothed based plate 102 containing the lock tooth 100 and the spring 112, is placed just inside the slotted drum 108 such that the toothed base plate 102 and the slotted drum 108 is coaxial.

4. The centrifugal starting system for an internal combustion engine as claimed in claim 1, wherein more than one lock tooth is used for engaging with the slotted drum 108.

5. The centrifugal starting system for an internal combustion engine as hereinabove described in the specification with the accompanying drawings