DESC:FIELD OF INVENTION
[0001] The present invention relates to a braking system for a two-wheeled vehicle and more particularly to a drum brake used on a two-wheeled vehicle.
BACKGROUND OF INVENTION
[0002] A drum brake typically comprises of a pair of brake shoe, a pair of springs to hold the two brake shoes, a hinge about which the brake shoes are pivoted and a cam which displaces the brake shoes radially outward to get in contact with the drum during the braking application. Such a braking system further comprises of a hub, ball bearings mounted on a hub on an axle. The wheel rotates on the axle axis.
[0003] For a drum brake to be compact it is desired that the above mentioned elements e.g. pair of brake shoe; pair of springs, cam and hinge are placed as closely as possible. In such a drum brake, a large amount of space is unused if the springs are attached to the middle portion of the brake shoes.
[0004] Furthermore, such drum brakes are provided with stiffening ribs on the inner surface of brake panel so as to increase the stiffness & strength of the brake panel. In such a braking system, again the size of the drum brake is increased as due to the stiffening ribs, it is required that the brake shoes, springs and hubs are mounted and located at a larger distance from the brake panel. Furthermore, to improve the stiffness and strength, it is necessary to increase the section thickness. Increasing section thickness is not desirable as it would lead to substantial increase in mass and cost. Hence, it is necessary to provide strengthening ribs on the panel without increasing the cost. But due to space constraints, it is not possible to provide ribs on the inner side of brake panel. Moreover, the braking system with such a brake panel has higher bending moment on the brake anchor/pivot due to its higher overhang if the strengthening ribs are provided on the inner side of brake panel.
[0005] In addition, the brake panel wherein the springs are attached to the lower portion of the brake shoes have an associated problem of brake shoe tilting. This brake shoe tilting leads to poor braking efficiency and also uneven wearing of brake shoe. During actuation of brake shoes, it is found that brake shoes tilt towards the brake Panel. This causes substantial reduction in the braking efficiency and leads to increase in stopping distance. Hence, it is desired to have a braking system wherein the tilting of the brake shoes is inhibited.
SUMMARY OF THE INVENTION
[0006] In order to obviate the limitations and the problems associated with the prior art, the current invention discloses a brake panel with the strengthening ribs on the side of brake panel which is opposite to the brake shoes, thereby leaving more space for the brake shoes and the springs. Placing the strengthening ribs on the side of brake panel opposite to brake shoes makes it possible to reduce the overhang of brake anchor (pivot pin), thereby reducing the bending moment acting on it and increasing the stiffness & structural rigidity of the brake panel.
[0007] Furthermore to avoid the tilting of the brake shoes towards the brake panel, the brake panel is provided with protruding profiles just below the two brake shoe pieces. Design of protruding profiles on brake panel surface below the brake shoes is optimized to support the brake shoes during its actuation, and thereby preventing the tilting of brake shoes.
[0008] The current invention discloses a more compact brake panel with high stiffness and structural rigidity leading to improved braking efficiency and reduced stopping distance. Other advantages include substantial reduction in weight of brake panel leading to significant reduction in cost of brake panel, lower weight which further leads to reduction in consumption of raw material (aluminum – scarce natural resource), being environment friendly and reduced emissions during casting process.
BRIEF DESCRIPTION OF DRAWINGS
[0009] Figure 1 illustrates a typical type two-wheeler.
[00010] Figure 2 illustrates brake assembled in one wheel of the vehicle.
[00011] Figure 3 illustrates inner construction of the disclosed brake.
[00012] Figure 4 illustrates sectional view of the assembled brake on the wheel.
[00013] Figure 5 illustrates perspective view of the brake.
[00014] Figure 6 illustrates cut section view through a plane passing through the protrusion on the brake panel.
[00015] Figure 7 illustrates cut section view through a plane passing through the protrusion on the brake panel.
[00016] Figure 8 illustrates the brake panel’s surface accommodating the brake shoes and springs.
[00017] Figure 9 illustrates the brake panel’s surface on opposite side of the brake shoe.
DETAILED DESCRIPTION OF THE INVENTION
[00018] The compact braking system as per the current invention is described herein discloses stiffener ribs on the brake panel surface opposite to the brake shoes, protruding portions to avoid the tilting, lesser overhang of the brake anchor and springs on the lower portion of the brake shoes to provide ample space for the brake shoes and springs. Placing the strengthening ribs on the side of brake panel opposite to brake shoes makes it possible to reduce the overhang of brake anchor (pivot pin), thereby reducing the bending moment acting on it and increasing the stiffness & structural rigidity of the brake panel.
[00019] Furthermore to avoid the tilting of the brake shoes towards the brake panel, the brake panel is provided with protruding profiles just below the two brake shoe pieces. Design of protruding profiles on brake panel surface below the brake shoes is optimized to support the brake shoes during its actuation, and thereby preventing the tilting of brake shoes.
[00020] The current invention discloses a more compact brake panel with high stiffness and structural rigidity leading to improved braking efficiency and reduced stopping distance. Other advantages include substantial reduction in weight of brake panel leading to significant reduction in cost of brake panel, lower weight which further leads to reduction in consumption of raw material, being environment friendly and reduced emissions during casting process.
[00021] Figure 1 shows a typical vehicle with a headlamp 1, fuel tank cap 2, fuel tank 3, front wheel 4A, rear wheel 4B, engine 5, floor board side panel 6, floor board 7, utility box 8, rider seat 9, two wheeler 10, head tube 11, tail lamp 12 and front brake 13. The brake as disclosed may be equipped to any of the front wheel 4A or rear wheel 4B.
[00022] Figure 2 shows wheel 4A, front brake panel 13, front brake panel hub 21, horizontal axis 22, cam lever 23 and axle axis 24. The brake is assembled on front brake panel hub 21. The cam lever 23 is actuated by using brake cable through a hand lever equipped to the handle. Axle axis 24 is the axis on which the wheel 4A rotates. The drum is attached to the hub which rotates with the wheel. On application of the brake, the brake shoes get in contact with the drum and due to friction in between the brake shoes and the drum, the wheel eventually stops.
[00023] Figure 3 shows internal construction of the brake with brake panel outer surface 13, cam lever 23, brake shoe first piece 31, hinge 32, front brake panel 33, axle 34, brake shoe second piece 35, first spring 36, cam 37, second spring 38 and brake panel inner surface 39. The brake shoe first piece 31 and brake shoe second piece 35 are pivoted on the hinge 32 and made able to rotate on the hinge 32 axis. The actuation for radially outward movement of the brake shoe first piece 31 and brake shoe second piece 35 is performed by the cam 37. The first spring 36 and second spring 38 each are connected at their two ends to the both brake shoe first piece 31 and brake shoe second piece 35 at a substantially lower portion of the brake shoe first piece 31 and brake shoe second piece 35. The cam lever 23, brake shoe first piece 31, hinge 32, front brake panel 33, axle 34, brake shoe second piece 35, first spring 36, cam 37, second spring 38 are placed over or on the brake panel inner surface 39.
[00024] Figure 4 shows cam lever 23, axle 34, first spring 36, brake panel 41, ball bearing 42, empty space 43, hub 44 and boss brake panel 45. On application of the cam lever 23, the brake shoe first piece 31 and brake shoe second piece 35 are pulled radially outward due to which the brake shoe lining 46 touches the drum 47 and due to friction in between the surfaces of brake shoe lining 46 and the drum 47, the wheel eventually stops.
[00025] Figure 5 shows cam lever 23, hinge 32, axle 34, first spring 36, and second spring 38 and cam 37. Figure 5 is the assembled brake of which cut section view has been shown in Figure 4. The brake shoe first piece 31 and brake shoe second piece 35 are enveloped on the outer periphery by the drum 47.
[00026] Figure 6 illustrates cut section view through a plane passing through the protrusion on the brake panel below each of the brake shoe first piece 31 and brake shoe second piece 35. Figure 6 shows front brake 13, cam lever 23, brake shoe first piece 31, brake shoe second piece 35, second spring 38, axle 34, protruding first profile 71 and protruding second profile 72. Protruding first profile 71 and protruding second profile 72 which lays in between the brake panel inner surface 39 and the brake shoe first piece 31 and brake shoe second piece 35. The protruding first profile 71 and protruding second profile 72 are preferably located at the centre of the brake shoe first piece 31 and brake shoe second piece 35.
[00027] Figure 7 illustrates the other half of the cut section view through a plane passing through the protrusion on the brake panel below each of the brake shoe first piece 31 and brake shoe second piece 35 as shown in Figure 6 shows brake shoe first piece 31, axle 34, brake shoe second piece 35, first spring 36, protruding first profile 71 and protruding second profile 72.
[00028] Figure 8 shows front brake 13, front brake inner panel 39, cam 37, cam lever 23, stiffening rib 82, stiffening rib 83, central stiffening rib 84, stiffening rib on outer periphery 85, protruding first profile 71 and protruding second profile 72. The Figure shows the location of the stiffening rib 82, stiffening rib 83, central stiffening rib 84, stiffening rib on outer periphery 85, otherwise the projected portion for providing stiffness lies on the other side of the panel opposite to one that houses the brake shoes more clearly shown in Figure 9.
,CLAIMS:I/We claim:
1. A braking system for wheel of a vehicle (10), the vehicle (10) comprising :
an axle (34) fixedly provided between a pair of front forks on an axle axis (24);
a pair of bearings (42), each holding the said axle (34);
a wheel hub (44) rotatably mounted on and extending between said pair of bearings (42), the wheel being attached to said wheel hub (44);
a drum brake assembly with a pair of brake shoes (31,35) connected by a pair of springs (36,38) on a brake panel (33); the brake shoes (31,35) pivotally hinged at one end and able to have radially outward displacement by action of a cam (10) at a second end;
characterized in that:
the pair of springs (36,38) connecting the brake shoes (31,35) are attached with an offset with respect to the central line (C) along width (W) of said brake shoes (31,35) and said brake panel (33) is provided with at least one protruding portion (71,72) underneath each brake shoes (31,35).
2. The braking system as claimed in Claim 1 wherein the protruding portion (71, 72) is located at substantially middle portion of each brake shoes (31, 35).
3. The braking system as claimed in Claim 1 wherein the brake panel (33) side opposite to the housing the brake shoes (31,35) and the said springs (36,38) is provided with stiffening ribs (82,83,84).