Combined braking system for two wheeler

Field of the Invention

The present invention relates to "Combined Braking System for two wheeler". In particular this invention relates to front and rear combined brake system for two-wheeled vehicle. Background of the invention

In most of the present two wheeler braking systems, both front and rear brakes are independently operated i.e. application of front brake force will activate only front wheel brake and rear brake force will activate only rear wheel brake. Rear brake force application is limited, because of dynamics of vehicle during braking. Due to load transfer to front wheel during braking, further increase in rear brake force will result in skidding rather than stopping the vehicle. Vehicle controlling becomes difficult and stopping distance will be more, thereby resulting in poor braking performance due to wheel skidding. So typically in a combined brake system the available braking force is completely utilised by distributing it to front and rear brake, thereby the stopping distance is minimized in two wheelers. As disclosed in JP2004352181 the interlocking brake device ( or combined braking system), has an interlocking brake manipulating cable which is connected to an intermediate portion of an equalizer lever, which forms a front wheel brake manipulating end portion at one end portion thereof and a rear wheel brake manipulating end portion at another end portion thereof, either one of the front brake cable and the rear brake cable is formed as one independent brake manipulating cable which is connected to an independent brake manipulating member, an engaging member which is capable of being engaged with and being disengaged from the equalizer lever is mounted on the independent brake manipulating cable. In this brake system arrangement, the equalizer lever can tilt towards the wall and hit the spring placed around it. This tilting can lead to mechanism lockage. And during this lockage the front brake application is not possible. Since one spring is used to retain the equalizer in its original position, much brake force is wasted to move the equalizer against the spring. The provision of engaging member resting on equalizer lever slot which is a integral part of the brake cable for sliding and relative rotation is subject to wear and tear for continuous rubbing and sliding inside the slot. To replace the said engaging member the entire cable has to be changed.

In another patent JP9058434 which discloses a longitudinal interlocking brake (or combined brake) practicable through a structure by applying a mechanism, which generates only rear wheel brake force in an early time of brake operating input, but as the brake operating input exceeds a prescribed value, it can generate braking force even at the front wheel. In the above said mechanism there is one input and two output for which the independent lever mechanism is placed longitudinally opposite to the combined lever mechanism, thereby during rear brake application, front brake activation line length is more. The problem associated with this is that it is incapable of providing good brake feel. Since there is only one input, the equalizer lever is not supported and guided during brake operation. At the end of rear brake application, application of the front brake will result in tilting of equalizer lever thereby hitting the wall.

In another patent JP2000309294 which discloses a interlocking brake system (or combined brake system) having an equalizer lever accommodated inside an equalizer case disposed near a head pipe, where a first input cable is connected to an interlocking brake lever which is axially supported at one end of a steering handle and is connected to a mid portion of the equalizer lever. Further a first output cable and a second output cable connected to a rear wheel brake and a front wheel brake are connected to a first end and a second end of the equalizer lever. In this kind of arrangement there is no support /guiding system for front brake circuit (i.e. is not guided). During rear brake operation, the resultant thrust coming on pin joint of intermediate arm can make front brake circuit to deflect in lateral direction of the cable. This results in mechanism lockage and rubbing of front brake wire with casing walls. The other disadvantage is front brake input cable end is free to slide in the slot due to improper guiding of the joint member the front brake input cable end may bend. For which more rear brake activation force is required during interlocking braking. Even the brake cable wire endpin rotation is not allowed inside that slot.

Unnecessary work is also done against the spring which is used in the front brake circuit for initiation for interlocking brake.

Hence the objective of the present invention is to overcome the above problems associated with the prior arts.

Summary of the Invention

An object of the present invention is to provide a combined braking system for two wheeled vehicle which provides better dynamics and safety during cornering.

Another object of the present invention is to provide a combined braking system for two wheeled vehicle where the brake circuits are guided properly thereby improving the braking feel.

Another object of the present invention is to provide a combined braking system for two wheeled vehicle which will allow free rotation to brake wires without affecting the operation of the mechanism.

Another object of the present invention is to provide a combined braking system for two wheeled vehicle where the front brake cable wire bending is avoided. Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.

Brief description of the drawing:

Figure 1 illustrates a conventional scooter type motorcycle.

Figure 2 illustrates the combined brake system with levers and brakes.

Figure 3 is the cross sectional view of combined brake system in assembly condition.

Figure 4 is the cross sectional view of combined brake system with both front and rear brake application

Figure 5 is the cross sectional view of combined brake system showing the starting of only rear brake force.

Figure 6 is a flowchart showing various stages of combined brake system.

Detailed Description of the Invention:

The present invention relates to combined braking system for a two wheeled. For the purpose of illustration a scooter of the general type is illustrated for the application.

Referring to Figure 1, the reference number 1 denotes a front wheel, 2 denotes a front fork, 3 denotes a front fender, 4 denotes a front cover, 5 denotes a glove box area, 6 denotes a handle bar cover, 7 denotes a headlight, 8 denotes a handle bar ,17 denotes a rear fender and 18 denotes tail lamp.

The center of the body forms a low floor board 9 for functioning as a part for putting feet and a under cowl 10 which is located below the rider's seat and covers at least a part of the engine, The under cowl is made up of metal or resin. The under cowl is hinged to the seat 11. A utility box 12 opens from the rear end to hinged portion. The utility box 12 is provided under the seat extending longitudinally of a vehicle body and the inside of the utility box has a large capacity so that a large article can be housed. A main frame 14 extended along the center of the body before and behind and made of a metallic pipe and is provided under the floor board 9. A swing type power unit 13 is coupled to the rear end of the main frame 14. A rear wheel 15 is supported on one side of the rear end of the swing type power unit 13. The swing type power unit 13 is suspended in the rear of a body frame. The side covers 16 both on left and right sides, covers the utility box 12 and other parts of the vehicle, thereby providing a good appearance to the vehicle. The combined brake system is located on the front part of the scooter type vehicle. A preferred embodiment of the present invention will be described hereunder with reference to the accompanying drawings.

With reference to Figure 2, the combined brake system or mechanism is housed within a container (101) located in the front part of the scooter type vehicle. The said container (101) protects the mechanism from dust. The entire said mechanism is mounted on the base surface of the container with mounting holes which is again fastened to mounting bracket of the vehicle frame. A first input cable (102) from one of the brake control lever (103) is connected to the equalizer lever (104). And a first output cable (105) and second output cable (106) is connected to rear brake (107) and front brake (108) respectively.

The second input cable (109) from brake control lever (110) is connected to a second output cable (106) through a mechanical arrangement, which is shown clearly in Figure 2.

Referring to Figure 2 and according to the first embodiment of the present invention, the first input cable (102) connected to the interlock brake lever is connected to the midway portion of the equalizer lever (104) through pin insert (201). The said first input cable (102) activates the combined brake circuit. The first output cable (105) connected to the rear wheel brake is connected at one of the end portion of the equalizer lever (104) through pin insert (202). The second input cable (109) is connected to the right side brake control lever and this front activation cable is supported by cable holder.,

When the independent brake lever is operated to pull the second input cable (109) the second output cable (106) is further pulled through many joint members, so that the front wheel brake can be operated independently. In this case, application of front brake lever will pull second input cable (109) which further pulls the sliding tube (202). The said sliding tube (202) guided by bracket (203) further pulls the slide rod (204) which transfers the cable wire (109) force to output cable (106). During front brake application, the said slide rod (204) slides in the cylindrical slider (206), single step washer (207) and double step washer (208). At the same time the slide tube (202) slides in the bracket (203). This sliding motion of the slide tube (202) and slide rod (204) will not impart any motion to equalizer lever (104). Due to this application of front brake lever, it activates only front brake.

Figure 3 shows the combined operation that is when both front and rear brake circuit act together.

The equalizer lever (104) connects the front and rear brake circuits. The said equalizer lever (104) is able to move up and down and swing within the container (101). The left end potion (301) of the said equalizer lever (104) is provided with a cylindrical slider (206) with two pins one at top and other at bottom, guided and supported by the slide rod (204). The said cylindrical slider (206) is having one flat surface at one side wherein the single step washer (207) rests. The double step washer (208) is provided with big step (302) and small step (303). A spring member (304) having low stiffness is supported between bracket (203) and big step (302) of double step washer (208).

Another spring member (305) having higher stiffness is supported between double step washer small step (303) and single step washer (207). A spacer (306) is mounted on bracket (203) and is preferably placed in the space between spring (304) and slide tube (202). The solid length of spring (304) is less than the spacer (306). The solid length of spring (305) is less than summation of single step washer length (207) and double step washer small step (303) length. During the assembly of the brake system (as shown in Figure 2) the equalizer lever (104) rests on the equalizer lever stopper bracket (307). With this arrangement during brake system assembly different pre play of the brake will not affect the mechanism configurations. The spring members 304 and 305 are preloaded equally to maintain the equilibrium of all said washers (207, 208) and cylindrical slider (206). The slide rod (204) slide tube (202), equalizer lever (104), input- output cable longitudinal axis is in one working plane. The equalizer lever (104) longitudinal axis 1 is not perpendicular to the slide rod (204) longitudinal axis at the beginning of the brake application (or in assembly condition shown in Figure 2).

Rear brake application pulls the cable wire (102) which further pulls the equalizer lever (104). During initial phase of the brake operation the brake cable (105) travel is more thereby the equalizer lever (104) rotates about the axis 3. After establishing brake liner and drum brake contact brake application requires more force with moderate displacement. After this equalizer lever longitudinal axis 1 comes to a position which is perpendicular to the brake cable axis 2. Further increase in brake force in cable wire (102) pulls the cable wire (105) and thereby applies the reaction force on single step washer (207) which rests on front brake circuit with double step washer (208) and spring member (305). The spring (305) gets compressed accordingly to maintain the equalizer lever (104) in perpendicular position. The slide tube (202) and the double step washer (208) assembly moves against the spring member (304).

On further application of rear brake as shown in Figure 4, the spring member 304 and 305 gets compressed. After pre determined travel of the slide tube (202) and double step washer (208) assembly, the double step washer big step (302) surface touches the spacer (306), this is in order to avoid further front brake force application. With this the front brake activation force limit gets controlled during combined braking and spring member (304) bottoming (becoming solid member) is also avoided with spacer (306).

By the time double step washer (208) makes contact with spacer (306) the distance between the single step washer (207) and double step washer (208) becomes zero. With this condition the equalizer lever one end (301) gets directly supported on the bracket (203). Further increase in brake force increases only rear brake force, during this the said equalizer lever (104) rotates about J1. To withstand high reaction force during this phase the equalizer lever end (301) is supported against the said stationary bracket (203).

With this mechanism the front brake can be applied at any point of the rear brake activation. Any brake loose in front brake circuit will not affect the initial rear brake allocation during combined brake application.

Figure 5 is the flowchart for combined brake system, showing various step involved in it.

It is further to be noted that the present invention is not limited to the described embodiment and many other changes and modifications may be made without departing from the scope of the appended claims.

We Claim:

1. A front wheel and rear wheel combined brake system for a two wheeler, each being mechanically operated, comprising:

a independent brake lever, preferably actuating a front brake;

an interlocking brake lever for actuating both front and rear brake;

a plurality of brake cables for transmitting the brake forces;

a movable force distributing lever for connecting said interlocking brake lever

and independent brake lever with respective brake cables; and

a sliding element to transfer the brake force from independent brake lever to one of the output brake cable.

2. The combined brake system as claimed in claim 1, wherein the said interlocking input brake cable is connected to a midway portion of the force distributing lever.

3. The combined brake system as claimed in claim 1, wherein the said independent input brake cable is connected to one end of the force distributing lever.

4. The combined brake system as claimed in claim 1, wherein the said sliding element comprises:

A slide tube; and

A sliding rod bolted to sliding tube;

Wherein the open end of the sliding rod is connected to the independent output brake cable; and

Wherein the open end of sliding tube is connected to the independent input brake cable.

5. The combined brake system as claimed in claim 1, wherein the said sliding element is guided by at least two brackets placed preferably at its two ends.

6. The combined brake system as claimed in claim 1 and claim 4, wherein the said force distributing lever is provided with a cylindrical slider on one end with at least two pins one at top and other at bottom, which is guided and supported by the slide rod.

7. The combined brake system as claimed in claim 1 and claim 4, wherein the said sliding element slides through joint members like washers, spacers, springs and brackets.

8. The combined brake system as claimed in claim 1, wherein the said system is housed inside a container.