Throttle control device for a motorcycle

Field of the invention

The present invention relates to a "Throttle control device for a motorcycle" and more particularly to throttle control system comprising a flexible cable and a cam control mechanism.

Background of the invention:

Generally, a throttle cable used in a two-wheeler such as a motorcycle or scooter to accelerate or decelerate the vehicle has an inner cable and an outer cable. Typically in the known art the outer cable is fixed or arrested to allow the movement of the inner cable. One end of the inner cable is attached to a constant radius slot provided on the throttle sleeve of throttle cable holder so that during the rotation of the throttle housing, the cable is wrapped in the slot in the throttle sleeve that results in cable pull. The other end of the inner cable is connected to the carburettor throttle slide so that when the cable is pulled by the throttle sleeve, the throttle slide moves up and down by which the rider can accelerate or decelerate the vehicle.

Therefore, in order to decrease or increase the cable pull rate the radius of the throttle sleeve could be varied accordingly and the cable pull rate, which here is the cable pull per unit rotation of the said throttle sleeve is constant. Moreover, in the current design the outer cable is fixed. This contemporary design in the two-wheeler technology forum brings about challenges of drivability and the acceleration feel, as they are two of the most important parameters in two wheeler designs. In order to achieve better ride, acceleration feel and drivability, the requirement of fuel flow rate can be different for low speeds and high speeds. This also however is difficult to achieve in the contemporary designs of the throttle control device. Present invention aims to address this issue of fuel flow rate control through throttle design. Moreover, the other avenue that this invention addresses is by providing more free play for better riding comfort and control. Free play in throttle control in a motorcycle is provided for better riding and handling of the vehicle during riding conditions. Having the proper amount of throttle free play is essential for smooth control of the throttle on the road. Too much free play makes fine control of the engine almost impossible. Moreover, increase in throttle free play will cause looseness in the throttle housing rotation and the rider may feel that in idle condition the vehicle is not responding. Too little free play can make the throttle stick without returning to idle conditions, which may lead to unsafe conditions.

Brief description of the invention

The present invention relates to a throttle control device, which includes a throttle cable holder that is mounted on a handle bar of a motorcycle and an operating means for controlling it. The operating means primarily include an inner flexible cable flanked or encompassed by a movable outer sleeve. The moveable outer sleeve includes a restricting device such as a spring or an equivalent that allows selective holding of the throttle in a predetermined position. Moreover, the invention also comprises a cam shaped variable radius throttle slot for controlling the cable pull rate.

Brief description of the drawings

Figure 1 illustrates side view of a motorcycle according to the present invention

Figure 2 illustrates cable pull vs. throttle rotation at different angles

Figure 3 illustrates front view of the throttle control according to the present invention

Figure 4 illustrates isometric view of the throttle control according to the present invention

Figure 5 illustrates schematic design of movable outer sleeve according to the present invention

Figure 6 illustrates standard design on throttle control

Figure 7 and 8 illustrate proposed designs on throttle control

Detailed description of the invention

A selected illustrative embodiment of the present invention will be now described with respect to the accompanying figures 1,2,3,4,5,6,7 and 8. A motorcycle comprises of a frame 101, front fork 102 attached to a pivot tube 103 of the vehicle frame 101, a front wheel 104 attached to these front forks 102, a handle bar 105 connected to the front forks 102, a fuel tank 106 attached so as to straddle an upper part of the vehicle frame 101, a seat 107 attached to the upper rear portion of the vehicle frame 101, an engine unit 108 attached to the lower front section of the vehicle frame 101, a swing arm 109 attached to a lower rear section of the vehicle frame 101, suspended by a rear shock absorber 110 from the vehicle frame 101 and a rear wheel 111 attached to a rear end of swing arm 109. The intake system of the engine (not shown in the figure) comprises of a carburettor, intake duct and an air cleaner. The exhaust system of the engine (not shown in the figure) comprises of exhaust pipe and a muffler.

The motorcycle is also provided with a side cover 112 for covering a side section of the vehicle frame 101, a seat cover (not shown in the figure) for covering a rear section of the vehicle frame 101 below the seat 107, a front fender 113 for covering an upper part of the front wheel 104, and a rear fender 114 for covering an upper part of the rear wheel 111. Figure 2 illustrates cable pull vs. throttle rotation angle. The line 1 in the figure 2 show the cable pull that is in practice for current designs, however the slope can be changed based on throttle slot radius. And the curves like 2 to 5 and combinations of these are the various possible options to vary the flow rate. Line 6 is in the ideal scenario. Also free-play in the throttle cable is essential to allow the flexing of cable during the steering control of the vehicle as well as to improve the feel of the throttle. But increase of free-play will cause looseness in the throttle housing rotation.

The throttle grip assembly 201 is operatively mounted upon the right hand portion of the motorcycle handle bar 105. Also mounted on the handle bar 105 is a conventional front brake lever assembly (not shown in the drawing) including its housing and front brake cable that may be of conventional construction. The motorcycle throttle grip assembly 201 includes a sleeve 202 rotatable with respect to the handle bar 105, an outer housing 203 that is hollow, and has a shell like construction. The sleeve 202 is received over the free end of the handle bar 105 and is dimensioned for smooth rotational movement with respect to the end portion of the handle bar 105. A rubber sheath 204 encloses the major portion of the sleeve 202 and furnishes a secure gripping surface for the operator's right hand. The inner cable 206 is arrested to the said sleeve 202. One of the most important aspect of the present invention is introduction of a free play in the outer sleeve 202 construction. In the present invention, the problem of optimum free play adjustment is eliminated completely by the design wherein the outer sleeve 202 is allowed to move to the required displacement. Also in order to arrest the looseness of throttle housing 203 and cable 206, a restricting device such as a spring 207 is used. Due to this design the throttle rotation angle is increased which is compensated by a variable cable pull rate that is achieved by a cam throttle slot 208 arrangement instead of a constant radius throttle slot.

Therefore the required amount of free play is achieved in the present embodiment wherein the same is incorporated in the outer sleeve 203 from anywhere between the handle bar end to the carburettor end. As the throttle is operated, initially the outer sleeve 202 moves against the spring 207 to the desired prefixed distance allowing free play, after which the movement is stopped either by the spring 207 or a stopper that can be provided. Apart from the outer sleeve 202, small movement of the inner flexible cable 206 can also be achieved.

The variable cable pull rate is achieved through a various radius slot 208 instead of a constant radius that varies the cable pull rate. The slot radius can be increased or decreased here and a combination of these with the throttle angle can be used for achieving the desired throttle cable pull rate. Figure 6 and 7 are different possible combinations to achieve the above said results. Here a variable radius R slot is used instead of a constant radius that varies the cable pull rate. The slot radius R can be increased or decreased and combination of these with throttle angle to achieve desired cable pull rate.

The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the claims.

Claims
We claim:

1. A throttle control device including a throttle cable holder mounted on a handle bar and a throttle control operating means mounted on the said throttle cable holder, the said throttle cable operating means comprises a inner flexible cable flanked by a movable outer sleeve which is restricted by a restricting device wherein, the said sleeve is adapted for receiving a handle grip thereover and the said control device comprises a restricting means for selectively holding the said throttle operating means in a predetermined position.

2. The throttle control device as claimed in claim 1, wherein the outer sleeve is allowed a pre-controlled movement, during throttle control operation, to allow free play.

3. The throttle control device as claimed in claim 1, wherein a restricting device that includes a spring and a stopper, which restricts the movement of the outer sleeve.

4. A throttle control device comprising a variable radius throttle slot for controlling the cable pull rate.

5. The variable radius throttle slot as claimed in claim 4, wherein the throttle slot used is preferably cam shaped.

6. A motorcycle having a throttle control device that includes a throttle cable holder mounted on a handle bar and a throttle control operating means mounted on the said throttle cable holder, the said throttle cable operating means comprises a inner flexible cable flanked by a movable outer sleeve which is restricted by a restricting device wherein, the said sleeve is adapted for receiving a handle grip thereover and the said control device comprises a restricting means for selectively holding the said throttle operating means in a predetermined position.