TWI899963B - Drum brake device - Google Patents

Abstract

A drum brake device suitable for disposed on a motorcycle wheel is provided. The drum brake device includes a brake drum, a first brake shoe, and an actuating mechanism. The brake drum is connected to the wheel, wherein the brake drum is capable of rotating about a central axis and includes a friction contact surface having a contact surface curvature radius. The first brake shoe is located inside the brake drum, wherein the first brake shoe includes a first friction material having a first outer surface with a first outer surface curvature radius smaller than the contact surface curvature radius. The difference between the first outer surface curvature radius and the contact surface curvature radius is between 1mm and 2mm. The actuating mechanism is located inside the brake drum and is connected to the first brake shoe.

Description

drum brake system

The present invention relates to a brake device, and more particularly to a drum brake device.

Conventional drum brake systems consist of a brake drum, a first brake shoe, a second brake shoe, and an actuator. When the user brakes, the first and second brake shoes are pushed apart by the actuator, contacting the brake drum and generating friction. Over time, drum brake systems can produce a noise when braking, especially in humid environments. This problem negatively impacts the user experience and is therefore urgently in need of a solution.

To address the problems of the prior art, embodiments of the present invention provide a drum brake device suitable for installation on a wheel of a motorcycle. The device comprises a brake drum, a first brake shoe, and an actuator. The brake drum is connected to the wheel and is adapted to rotate about an axis. The brake drum includes a friction contact surface having a contact surface curvature radius. A first brake shoe is disposed within the brake drum, wherein the first brake shoe includes a first friction material having a first outer surface having a first outer surface curvature radius, the first outer surface curvature radius being smaller than the contact surface curvature radius, and the difference between the first outer surface curvature radius and the contact surface curvature radius is between 1 mm and 2 mm. An actuating mechanism is disposed within the brake drum and connected to the first brake shoe. In an unactuated state, the first friction material does not contact the brake drum. In an actuated state, the actuating mechanism actuates to push the first brake shoe, causing the first friction material to contact the brake drum to apply the brake.

In one embodiment, the drum brake device further includes a second brake shoe, which is arranged in the brake drum, wherein the actuating mechanism includes a base, an actuating unit and a pin, the pin is arranged on the base, the first brake shoe is opposite to the second brake shoe, the first brake shoe is connected to the pin and is suitable for rotating relative to the pin, and the second brake shoe is connected to the pin and is suitable for rotating relative to the pin. In the non-actuated state, the actuating unit does not push the first brake shoe and the second brake shoe. In the actuated state, the actuating unit pushes the first brake shoe and the second brake shoe.

In one embodiment, the friction contact surface has a reference point. When the motorcycle moves forward, the reference point passes through the actuating unit, then passes through the first brake shoe, and then passes through the second brake shoe.

In one embodiment, the second brake shoe includes a second friction material, the second friction material has a second outer surface, the second outer surface has a second outer surface curvature radius, and the first outer surface curvature radius is smaller than the second outer surface curvature radius.

In one embodiment, the second outer surface curvature radius is less than or equal to the contact surface curvature radius.

In one embodiment, the axis line passes through the center of curvature of the friction contact surface. In the unactivated state, the axis line does not pass through the center of curvature of the first outer surface.

In one embodiment, in the non-actuated state, a distance between the center of curvature of the friction contact surface and the center of curvature of the first outer surface is between 0.5 mm and 1 mm.

In one embodiment, in the unactivated state, the center of curvature of the first outer surface is closer to the pin than the center of curvature of the friction contact surface.

In one embodiment, in the unactivated state, the axis line passes through the center of curvature of the second outer surface.

In one embodiment, the actuating mechanism further includes a spring, one end of the spring is connected to the first brake shoe, and the other end of the spring is connected to the second brake shoe, and the actuating unit includes a cam.

After research, the applicant discovered that when the actuating unit is actuated, the first outer surface of the first friction material of the first brake shoe will contact the friction contact surface of the brake drum. Before the contact point between the two, an angle is formed between the tangent of the first outer surface and the tangent of the friction contact surface. The size of this angle is the key factor affecting the brake noise. In particular, if the angle can be maintained at a value close to 0 but not equal to 0, the problem of brake noise can be effectively improved. Therefore, through the design of the first embodiment of the present invention in which the curvature radius of the first outer surface is smaller than the curvature radius of the contact surface, the problem of brake noise can be effectively improved. In addition, if the axis line of the second embodiment of the present invention does not pass through the center of curvature of the first outer surface, the effect of reducing braking noise can be further extended.

Referring to FIG. 1 , it shows the appearance of a motorcycle M according to an embodiment of the present invention, including components such as a fascia 91 , front wheels 92 , rear wheels 93 , a seat 94 , and a power system 95 .

The motorcycle M comprises a front section, a middle section, and a rear section. The front section of the motorcycle M includes components such as the steering wheel 91, front wheels 92, turn signals, and a keyhole. The middle section of the motorcycle M includes components such as the powertrain 95, seat 94, and footrest. The rear section of the motorcycle M includes components such as the taillights, rear wheels 93, and fenders.

Faucet 91 controls the direction of motorcycle M. Functional components, including instruments, switches, and rearview mirrors, may be installed on faucet 91. Faucet 91 also has handles (including a gas handle) and a handbrake. The user can control the direction of faucet 91 using the handles, adjust the throttle angle of the power system 95 to control power output using the gas handle, and decelerate motorcycle M using the handbrake. Faucet 91 may also be equipped with a main light, which provides primary illumination for motorcycle M.

The faucet 91 and the front wheel 92 are connected via a faucet rotating shaft. By rotating the faucet 91, the angle of the front wheel 92 can be controlled, thereby controlling the direction of travel of the motorcycle M.

The power system 95 is connected to and drives the rear wheel 93, thereby providing power to the motorcycle M and moving the motorcycle M forward.

Figure 2A shows a drum brake device according to the first embodiment of the present invention, wherein the actuator is in an unactivated state. Referring to Figure 2A , the drum brake device B1 according to the first embodiment of the present invention is suitable for installation on the wheel of the aforementioned motorcycle. The drum brake device B1 includes a brake drum 3, a first brake shoe 1, and an actuator 4. The brake drum 3 is connected to the wheel. The brake drum 3 is adapted to rotate about an axis L and includes a friction contact surface 31 having a contact surface curvature radius R31. The first brake shoe 1 is arranged in the brake drum 3, wherein the first brake shoe 1 includes a first friction material 11, the first friction material 11 has a first outer surface 111, and the first outer surface 111 has a first outer surface curvature radius R11, and the first outer surface curvature radius R11 is smaller than the contact surface curvature radius R31. In one embodiment, the difference between the first outer surface curvature radius R11 and the contact surface curvature radius R31 is between 1 mm and 2 mm.

Figure 2B shows the drum brake device of the first embodiment of the present invention, with the actuator in an activated state. Referring to Figures 2A and 2B, the actuator 4 is disposed within the brake drum 3 and connected to the first brake shoe 1. In an unactivated state (Figure 2A), the first friction material 11 does not contact the brake drum 3. In an activated state (Figure 2B), the actuator 4 is activated to push the first brake shoe 1, causing the first friction material 11 to contact the brake drum 3, thereby applying the brakes.

With reference to Figures 2A and 2B, in one embodiment, the drum brake device B1 further includes a second brake shoe 2, which is disposed within the brake drum 3, wherein the actuating mechanism 4 includes a base 41, an actuating unit 42, and a pin 43, wherein the pin 43 is disposed on the base 41, the first brake shoe 1 and the second brake shoe 2 are opposite each other, the first brake shoe 1 is connected to the pin 43 and is adapted to rotate relative to the pin 43, and the second brake shoe 2 is connected to the pin 43 and is adapted to rotate relative to the pin 43. In the non-actuated state (Figure 2A), the actuating unit 42 does not push the first brake shoe 1 and the second brake shoe 2. In the actuated state (Figure 2B), the actuating unit 42 pushes the first brake shoe 1 and the second brake shoe 2.

With reference to Figures 2A and 2B, in one embodiment, the friction contact surface 31 has a reference point P. When the motorcycle moves forward, the reference point P passes the actuator 42, then the first brake shoe 1, and then the second brake shoe 2. In Figures 2A and 2B, when the motorcycle is moving forward, the brake drum 3 rotates clockwise. The above disclosure does not limit the present invention.

2A and 2B , in one embodiment, the second brake shoe 2 includes a second friction material 21 , the second friction material 21 having a second outer surface 211 , the second outer surface 211 having a second outer surface curvature radius R21 , and the first outer surface curvature radius R11 is smaller than the second outer surface curvature radius R21 .

2A and 2B , in one embodiment, the second outer surface curvature radius R21 is less than or equal to the contact surface curvature radius R31.

2A and 2B , in one embodiment, the actuating mechanism 4 further includes a spring 44 , one end of the spring 44 is connected to the first brake shoe 1 , and the other end of the spring 44 is connected to the second brake shoe 2 , and the actuating unit 42 is a cam.

Figure 2C shows a partial enlargement of Figure 2B. Referring to Figures 2B and 2C, when the actuator 42 is actuated, the first outer surface 111 of the first friction material 11 of the first brake shoe 1 contacts the friction contact surface 31 of the brake drum 3. Prior to this point of contact, an angle θ is formed between the tangent of the first outer surface 111 and the tangent of the friction contact surface 31. This angle θ approaches zero but is not equal to zero (because the first outer surface curvature radius R11 is smaller than the contact surface curvature radius R31). This prevents the friction material from producing braking noise in humid environments.

Figure 3A shows the drum brake device of the second embodiment of the present invention, wherein the actuating mechanism is in an unactivated state. Figure 3B shows the drum brake device of the second embodiment of the present invention, wherein the actuating mechanism is in an activated state. The drum brake device B2 of the second embodiment of the present invention is substantially similar in structure to the drum brake device B1 of the aforementioned first embodiment of the present invention, and the main difference between the two lies in the position of the center of curvature of the first outer surface. In the first and second embodiments of the present invention, the axis line L passes through the center of curvature of the friction contact surface. However, referring to Figures 3A and 3B, in the second embodiment of the present invention, in the unactivated state, the axis line L does not pass through the center of curvature C1 of the first outer surface 111.

3A and 3B , in one embodiment, in the non-activated state, the distance between the center of curvature of the friction contact surface 31 (i.e., the axis L indicated in the drawing) and the center of curvature C1 of the first outer surface 111 is between 0.5 mm and 1 mm.

3A and 3B , in one embodiment, in the non-actuated state, relative to the center of curvature of the friction contact surface 31 (i.e., the axis L indicated in the drawing), the center of curvature C1 of the first outer surface 111 is closer to the pin 43 .

3A and 3B , in the non-activated state, the axis L passes through the center of curvature of the second outer surface 211 .

Figure 3C shows a partial enlargement of Figure 3B. Referring to Figures 3B and 3C, as in the first embodiment, when the actuator 42 is actuated, the first outer surface 111 of the first friction material 11 of the first brake shoe 1 contacts the friction contact surface 31 of the brake drum 3. Prior to this point of contact, an angle θ is formed between the tangent of the first outer surface 111 and the tangent of the friction contact surface 31. This angle θ approaches zero but is not equal to zero (because the first outer surface curvature radius R11 is smaller than the contact surface curvature radius R31). This prevents the friction material from producing braking noise in humid environments.

FIG4A shows the drum brake device of the second embodiment of the present invention after long-term use, wherein the actuating mechanism is in an actuating state. FIG4B shows a partially enlarged view of FIG4A. With reference to FIG3A, 4A, and 4B, after long-term use of the drum brake device of the second embodiment of the present invention, the first friction material 11 will become thinner, and the first outer surface curvature radius R11 of the first outer surface 111 of the first friction material 11 will change due to wear. However, due to the aforementioned design that the axis line L does not pass through the center of curvature C1 of the first outer surface 111 (FIG3A), the angle θ will still remain close to 0 but not equal to 0 to avoid the generation of abnormal braking noise.

After research, the applicant discovered that when the actuating unit 42 is actuated, the first outer surface 111 of the first friction material 11 of the first brake shoe 1 will contact the friction contact surface 31 of the brake drum 3. Before the contact point between the two, an angle θ is formed between the tangent of the first outer surface 111 and the tangent of the friction contact surface 31. The size of this angle θ is the key factor affecting the brake noise. In particular, if the angle θ can be maintained at a value close to 0 but not equal to 0, the problem of brake noise can be effectively improved. Therefore, through the design of the first embodiment of the present invention in which the curvature radius R11 of the first outer surface is smaller than the curvature radius R31 of the contact surface, the problem of brake noise can be effectively improved. In addition, if the axis line L of the second embodiment of the present invention does not pass through the curvature center C1 of the first outer surface 111, the effect of reducing the braking noise can be further extended.

In the embodiments of the present invention, a fuel-powered motorcycle is used as an example. However, the above disclosure does not limit the present invention. The motorcycle defined in the present invention may include a fuel-powered motorcycle, an electric motorcycle, or other motor vehicles.

Although the present invention has been disclosed above with specific preferred embodiments, they are not intended to limit the present invention. Anyone skilled in the art may make slight modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the scope of the attached patent application.

B1, B2: Drum brake system 1: First brake shoe 11: First friction material 111: First outer surface R11: First outer surface curvature radius 2: Second brake shoe 21: Second friction material 211: Second outer surface R21: Second outer surface curvature radius 3: Brake drum 31: Friction contact surface R31: Contact surface curvature radius 4: Actuator 41: Base 42: Actuator unit 43: Pin 44: Spring L: Axis axis P: Reference point θ: Interference angle C1: Center of curvature M: Vehicle 91: Fascia 92: Front wheel 93: Rear wheel 94: Seat 95: Powertrain

Figure 1 shows the exterior of a motorcycle according to an embodiment of the present invention. Figure 2A shows the drum brake device according to the first embodiment of the present invention, wherein the actuating mechanism is in an unactivated state. Figure 2B shows the drum brake device according to the first embodiment of the present invention, wherein the actuating mechanism is in an activated state. Figure 2C shows an enlarged view of a portion of Figure 2B. Figure 3A shows the drum brake device according to the second embodiment of the present invention, wherein the actuating mechanism is in an unactivated state. Figure 3B shows the drum brake device according to the second embodiment of the present invention, wherein the actuating mechanism is in an activated state. Figure 3C shows an enlarged view of a portion of Figure 3B. Figure 4A shows the drum brake device of the second embodiment of the present invention after extended use, with the actuator in an actuated state. Figure 4B is an enlarged view of a portion of Figure 4A.

B1: Drum brake system

1: First brake shoe

11: First friction material

111: First outer surface

R11: First outer surface curvature radius

2: Second brake shoe

21: Second friction material

211: Second outer surface

R21: Second outer surface curvature radius

3: Brake drum

31: Friction contact surface

R31: Contact surface curvature radius

4:Actuating mechanism

41: Base

42: Actuator unit

43: Sales

44: Spring

L: axis

P: Reference point

Claims (7)

A drum brake device, adapted to be mounted on a wheel of a motorcycle, comprises: A brake drum connected to the wheel, wherein the brake drum is adapted to rotate about an axis, the brake drum including a friction contact surface having a contact surface curvature radius; A first brake shoe disposed within the brake drum, wherein the first brake shoe comprises a first friction material having a first outer surface having a first outer surface curvature radius, the first outer surface curvature radius being smaller than the contact surface curvature radius, and the difference between the first outer surface curvature radius and the contact surface curvature radius being between 1 mm and 2 mm; An actuating mechanism disposed within the brake drum and connected to the first brake shoe. In an unactuated state, the first friction material does not contact the brake drum. In an actuated state, the actuating mechanism actuates to push the first brake shoe, causing the first friction material to contact the brake drum to apply the brake; and A second brake shoe is disposed within the brake drum. The actuating mechanism includes a base, an actuating unit, and a pin. The pin is disposed on the base. The first brake shoe and the second brake shoe are opposed to each other. The first brake shoe is connected to the pin and adapted to rotate relative to the pin. The second brake shoe is connected to the pin and adapted to rotate relative to the pin. In the unactuated state, the actuating unit does not push the first brake shoe and the second brake shoe. In the actuated state, the actuating unit pushes the first brake shoe and the second brake shoe. The friction contact surface has a reference point. When the motorcycle moves forward, the reference point passes the actuating unit, then the first brake shoe, and then the second brake shoe. The second brake shoe includes a second friction material having a second outer surface. The second outer surface has a second outer surface curvature radius, and the first outer surface curvature radius is smaller than the second outer surface curvature radius. A drum brake device as described in claim 1, wherein the radius of curvature of the second outer surface is less than or equal to the radius of curvature of the contact surface. A drum brake device as described in claim 1, wherein the axis line passes through the center of curvature of the friction contact surface, and in the non-actuated state, the axis line does not pass through the center of curvature of the first outer surface. A drum brake device as described in claim 3, wherein, in the non-actuated state, the distance between the center of curvature of the friction contact surface and the center of curvature of the first outer surface is between 0.5 mm and 1 mm. A drum brake device as described in claim 4, wherein, in the non-actuated state, the center of curvature of the first outer surface is closer to the pin than the center of curvature of the friction contact surface. A drum brake device as described in claim 3, wherein, in the non-actuated state, the axis line passes through the center of curvature of the second outer surface. A drum brake device as described in claim 1, wherein the actuating mechanism further includes a spring, one end of the spring is connected to the first brake shoe, and the other end of the spring is connected to the second brake shoe, and the actuating unit includes a cam.