ENGINE INITIATION SYSTEM FOR A SADDLE TYPE VEHICLE

FIELD OF THE INVENTION

[0001] The present subject matter relates generally to an engine initiation mechanism, and more particularly, to a one way clutch for a saddle type vehicle.

BACKGROUND OF THE INVENTION

[0002] A conventional engine initiation system is shown in FIG. 2. In the conventional engine initiation system, a starter motor 201 is rotatably connected to a starter gear 203 through an idler gear. When the starter motor 201 is actuated, the driving force of the starter motor 201 is transmitted from starter gear 203 to an inner race of the starter gear boss 205 (on which a one way clutch 206 rests) to a magneto mounted on a crankshaft 204 of an engine thereby starting the engine. After the engine attains operation, the one way clutch 206 slips and prevents transmission of torque to the starter gear 203.

[0003] In this arrangement, the one way clutch 206 is typically interposed between the starter gear 203 and a magneto rotor 207 and is mounted over the starter gear boss (or a hub) 205 as shown schematically in FIG. 1. However, this arrangement has a few drawbacks. First, the present engine initiation system is lengthy in the lateral (axial) direction and occupies space. Second, the inner race of the one way clutch is supported for rotation on the crankshaft by a needle roller bearing 212 to transfer load to crankshaft during torque transmission by one way clutch. The needle roller bearing 212 increases the weight and friction of the engine as well as the cost of manufacturing the engine. Third, in the present arrangement, one way clutch always rotates with the magneto during the engine initiation process as well as during engine operation. The rotating one way clutch causes additional rotational inertia to the magneto which is undesirable.

[0004] Further, the location and mounting arrangement of the one way clutch limits lubrication to the one way clutch because the starter gear completely covers the one way clutch on one side and other side is covered by magneto.

[0005] Hence, the present subject matter is directed to overcome all or any of the problems as set forth above and obviate the lacunae in the prior art. Therefore, it is an object of the present invention to disclose an engine initiation system comprising a one way clutch in which the length of the engine initiation system in an axial direction is reduced thereby saving space. Another object of the present invention is to provide an efficient one way clutch disposed with a starter gear thereby reducing the rotational inertia of magneto during engine working and having access to better lubrication. Yet another object of the present invention is to provide a cost effective engine initiation system where the needle roller bearing is eliminated and hence cost of manufacturing of the engine is reduced.

SUMMARY OF THE INVENTION

[0006] To this end, the present invention discloses an engine initiation system for an internal combustion engine comprising a starter motor, a starter gear receiving torque from the starter motor through an idler gear and having an inner circumferential surface and outer circumferential surface, a one way clutch further comprising a plurality of torque transmitting members rotatably supported on a hub forming an inner race of the one way clutch, a clutch housing for the one way clutch; wherein the one way clutch is disposed inner to the inner circumferential surface of the said starter gear, the one way clutch being co-axial with the starter gear such that the one way clutch and the starter gear always rotate simultaneously and collectively.

[0007] According to an aspect of the present invention, an outer race of one way clutch is circumferentially surrounded by and in contact with the clutch housing. Moreover, the hub for the one way clutch is supported on a crankshaft and includes a bush projected from a magneto rotor.

[0008] According to a further aspect of the present invention, the clutch housing is circumferentially fitted with the starter gear through known joining mechanism providing concentric mounting such that the clutch housing is in contact with the inner circumferential surface of the starter gear.

[0009] The foregoing objectives and summary provide only a brief introduction to the present subject matter. To fully appreciate these and other objects of the present subject matter as well as the subject matter itself, all of which will become apparent to those skilled in the art, the ensuing detailed description of the subject matter and the claims should be read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[00010] The above and other features, aspects, and advantages of the subject matter will be better understood with regard to the following description, appended claims and accompanying drawings where:

FIG. 1 shows a schematic flowchart of an engine initiation system according to the prior art.

FIG. 2 illustrates the engine initiation system according to the prior art.

FIG. 3 illustrates a typical saddle type vehicle in the form of a motorcycle.

FIG. 4 depicts the rear view of an engine initiation system according to the present invention.

FIG. 5 shows the front and side view of a starter gear according to an embodiment of the present invention.

FIG. 6 shows the sectional view of the engine initiation system according to the present invention.

FIG. 7 shows the front and side view of the one way clutch according to the present invention.

FIG. 8 shows a schematic flowchart of the engine initiation system according to the present invention.

FIG. 9 shows a graph illustrating the starter gear rpm, one way clutch rpm and engine rpm with time according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[00011] The subject matter described herein relates to the engine initiation system for an internal combustion engine in a saddle type vehicle. It is to be noted that the present subject matter is equally workable with any saddle type vehicle capable of accommodating the said engine initiation system in its internal combustion engine, including a motorcycle or a scooter type motorcycle.

[00012] Further "front" and "rear", and "left" and "right" wherever referred to in the ensuing description, refer to front and rear, and left and right directions as seen in a state of being seated on a seat of the saddle type vehicle. Furthermore, a longitudinal axis refers to a front to rear axis relative to the vehicle, while a lateral axis refers generally to a side to side, or left to right axis relative to the vehicle. Various other features and embodiments of the engine initiation system according to the present subject matter here will be discernible from the following further description thereof, set out hereunder.

[00013] FIG. 3 illustrates a typical saddle type vehicle in the form of a motorcycle capable of accommodating the present invention. A typical motorcycle 1 comprises a body frame assembly made up of a number of tubes welded together. The motorcycle 1 has a steerable front wheel 11 and a driven rear wheel 12. The body frame primarily includes a head pipe 101, a main tube enclosed by various motorcycle components and a down tube 102. The head pipe 101 is disposed at a front end of the body frame of the motorcycle and a front fork 103 rotatably carries the front wheel 11. The front fork 103 may be connected to the head pipe 101 by any known type of suspension system. The head pipe 101 supports a steering shaft (not shown) disposed inside the head pipe 101. The upper and lower ends of the steering shaft are fixed on an upper bracket and the under bracket. The front end of the main tube and an upper end of the down tube 102 are connected to the head pipe 101. The down tube 102 extends obliquely downward in front of an engine 200 from the head pipe 101 whereas the main tube extends rearward from the front end thereof.

[00014] A front fender 104 is provided below the under bracket to avoid the motorcycle and its occupants from being splashed with mud. A fuel tank 105 is disposed above the main tube, on the upper side of the engine 200, for storing the fuel for propelling the motorcycle 1. A seat 106 for a driver and a pillion is further provided, with the said seat being placed behind the fuel tank 105 and rearwardly of the main tube.

[00015] The rear wheel 12 revolves about a central axle 13. The axle 13 is supported at each end by a swing arm 14, the swing arm in turn pivotally connected to the body frame of the motorcycle by a rear shock absorber 300. Generally a motorcycle may use any of the two arrangements for rear shock absorbers, namely dual shock and mono shock. However the present invention is exemplified through a dual shock absorber. The dual shock absorbers are fixed at their upper ends to the motorcycle frame. Their lower ends are fixed to the swing arm 14.

[00016] The engine 200 is disposed below the main tube, and the main tube supports it. The engine may be an engine of a water-cooled type or air-cooled type. Drive force output from the engine is transmitted to the rear wheel 12 via a chain. The engine is initially powered by a starter motor.

[00017] The engine initiating system according to the present invention is now explained with the help of FIGS 4-8. The engine initiation system using a one way clutch includes a starter motor 201 which is driven by the power supplied from a power source, idler gear 202, a starter gear 203 which receives a driving force from the starter motor 201 through the idler gear 202, a one way clutch 206 and a clutch housing 210 for the one way clutch 206. The said system employs a magneto mounted over a magneto rotor 207 and is connected to the crankshaft 204 by the one way clutch 206 which permits rotation of the magneto only in one direction. The magneto located on lateral side of the engine 200 is enclosed by flywheel housing and generates electric power that is used for the engine operation.

[00018] The structure of the starter gear 203 according to one embodiment of the present invention is shown in FIG. 5. Axially, the starter gear has two surfaces, namely a magneto surface facing towards the magneto and an engine surface facing towards the rest of the engine. Circumferentially, the starter gear 203 has a continuous inner circumferential surface 215 in contact with the one way clutch and a non-continuous outer circumferential surface 216 where a plurality of spaced protrusions 209 is present. Largely, the magneto surface of the starter gear is continuous, is elevated near to starter gear axis and tapered towards the outer circumference. The engine surface is not continuous.

[00019] A schematic diagram of the mounting of the one way clutch according to the present invention is shown in FIG. 6. In the proposed arrangement, the one way clutch 206 rests on a hub 205 which forms the inner race of the one way clutch. The said hub 205 may be a flange or a bush projected from the magneto rotor 207, the magneto rotor 207 attached to the crankshaft 204 by means of a known joining mechanism. Further, the one way clutch 206 includes an outer race and a plurality of torque transmitting members 211 interposed between the inner race and the outer race to transmit the torque received from the starter motor 201. The outer race includes a flange 208 on the starter gear 203 in the axial direction and extending radially outwards from the starter gear. The torque transmitting members 211 are rotatably supported on the hub 205 on one side and the hub 205 is further supported on the crankshaft 204. The torque transmitting members 211 are partially ensconced in the clutch housing 210 on the other side as shown in FIG. 7. In a preferred embodiment, the one way clutch is a roller type clutch having roller elements as torque transmitting members.

[00020] The one way clutch 206 is co-axial with the starter gear 203 so that both of them rotate together in the rotatable direction of the one way clutch during the engine initiation process only, unlike the prior art. The one way clutch housing 210 is connected to the inner circumferential surface 215 of the starter gear 203 through a known mechanism, preferably press fitting, so that the starter gear 203 circumferentially engulfs the one way clutch 206 in such a way that the outer surface of the clutch housing 210 is in contact with the inner circumferential surface 215 of the starter gear 203. Hence the outer race of one way clutch is circumferentially surrounded by and in contact with the clutch housing and the one way clutch is disposed inner to the inner circumferential surface 215 of the starter gear 203.

[00021] The operation of the one way clutch is now described. When the starter motor 201 is actuated, the driving force of the starter motor 201 is transmitted to the starter gear 203 through the idler gear 202. As the starter gear 203 rotates, the torque transmitting members 211 of the one way clutch 206 rotate about the said hub 205. Thus the starter gear 203 and the one way clutch 206 rotate in the same direction. The one way clutch 206 prevents the starter gear 203 from rotating in the opposite direction. The driving force thus transmitted from the starter gear 203 is transferred to the crankshaft 204 through the engaged one way clutch 206 which rotates about the hub. After the engine starts, the crankshaft overruns and is synchronized with the rotation of the engine whereby the one way clutch idles and the starter gear is stopped. A flowchart of the engine initiation process according to the present invention is shown in FIG. 8.

[00022] FIG. 9 shows a graph illustrating the starter gear rpm, one way clutch rpm and engine rpm with time according to the present invention. It shows that after achieving significant rpm (revolutions per minute) during engine initiation, the starter gear and one way clutch donot rotate further while the engine continues to attain greater rpm. This is possible only because the one way clutch is now mounted inner to the inner circumferential surface of the starter gear due to which the starter gear and one way clutch as a whole are co-axial and act as one element.

[00023] The present subject matter and its equivalent thereof offer many advantages, including those which have been described henceforth. Unlike the prior art where the one way clutch was held between the starter gear and the magneto, the one way clutch in the present invention is mounted circumferentially within the starter gear, i.e., the starter gear itself circumferentially embeds the one way clutch. Because of this, the overall length of the engine initiation system is reduced and a space equivalent to the width of the one way clutch is saved. Moreover, in the present construction the starter gear does not cover the one way clutch completely from one side. Hence, the proposed arrangement allows better lubrication to one way clutch as the one way clutch directly faces the lubricants draining out from the cylinder head. A lubrication jet from crankcase is also provided for direct lubrication.

[00024] Further, in the present invention, the one way clutch and the starter gear rotate only during engine initiation process. Thus, the rotational inertia of the magneto is reduced, which due to its connection with the crankshaft, rotates along with the crankshaft once the engine is started. The present invention does not require a needle roller bearing and the same is eliminated. Thus the present invention also has the incidental advantage of comparative cost reduction as well as weight reduction.

[00025] The present subject matter is thus described. The term "engine initiation" is used to mean "cranking" in the above description. The embodiments described are chosen to provide an illustration of principles of the invention and its practical application to enable thereby one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. Therefore the forgoing description is to be considered exemplary, rather than limiting, and the true scope of the invention is that described in the appended claims.

We claim:

1. An engine initiation system for an internal combustion engine comprising:

a starter motor,

a starter gear receiving driving force from the starter motor through an idler gear and having an inner circumferential surface and outer circumferential surface,

a one way clutch, the one way clutch further comprising a plurality of torque transmitting members rotatably supported on a hub forming an inner race of the one way clutch,

a clutch housing for the one way clutch;

wherein the one way clutch is disposed inner to the inner circumferential surface of the said starter gear, the one way clutch being co-axial with the starter gear such that the one way clutch and the starter gear always rotate simultaneously and collectively.

2. The engine initiation system as claimed in claim 1, wherein an outer race of one way clutch is circumferentially surrounded by and in contact with the clutch housing.

3. The engine initiation system as claimed in claim 1 or claim 2, wherein the clutch housing is circumferentially fitted with the starter gear through known joining mechanism providing concentric mounting such that the clutch housing is in contact with the inner circumferential surface of the starter gear.

4. The engine initiation system as claimed in claim 1, wherein the radial surfaces of the one way clutch are substantially exposed to a lubricant.

5. The engine initiation system as claimed in claim 1, wherein the one way clutch includes a clutch having torque transmitting members, preferably a roller clutch.

6. The engine initiation system as claimed in claim 1, wherein the hub for the one way clutch is supported on a crankshaft and includes a bush projected from a magneto rotor.

7. The engine initiation system substantially as herein described and illustrated with reference to the accompanying drawings.