Heavy-Duty Brake Pad Retraction Spring With Rotor Stop Surface
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Solution Overview
Problem
Air actuated heavy vehicle disc brakes lack mechanisms to actively retract brake pads after braking, leading to residual drag, increased wear, and potential damage to components, with existing solutions being complex and costly to manufacture.
Innovation Solution
A brake assembly with a pad retraction spring having a supporting portion that abuts a stop surface and engaging portions that directly contact the backplates, preventing the spring from entering the enclosed volume and minimizing additional components, thus reducing manufacturing costs and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a pad retraction spring is provided to actively retract brake pads, then rotor drag is reduced and fuel economy is improved, but the spring may become dislodged and contact the brake rotor causing damage
Solution Approach 1:
A dedicated stop surface is introduced as an intermediary element between the pad retraction spring and the brake rotor. This stop surface acts as a mediator that defines the radial limit of the spring's movement, preventing the spring from contacting the rotor while still allowing the spring to effectively retract the brake pads and reduce rotor drag.
Solution Approach 2:
The stop surface is pre-positioned on the brake pad assembly to establish a predetermined radial boundary before the spring is installed. This preliminary positioning ensures that the spring's retraction force is effectively applied to reduce rotor drag while the pre-established stop surface prevents excessive radial movement that could cause the spring to contact the rotor.
2Ease of operation
If known pad retraction springs engage both brake pads and straddle the brake rotor, then pad retraction is achieved, but the design becomes complex and expensive to manufacture
Solution Approach 1:
The stop function is extracted from the pad retraction spring itself and transferred to a separate stop surface on the brake pad assembly. This separation allows the spring to be a simpler component focused solely on providing retraction force, while the stop surface handles the positional constraint, thereby reducing overall system complexity and manufacturing cost.
Solution Approach 2:
The brake pad assembly is designed to provide its own stop surface that inherently limits the spring's radial movement. This self-service approach eliminates the need for additional external components or complex spring structures, as the system uses its own existing components to achieve both pad retraction and positional stability.
3Force
If the pad retraction spring is positioned radially inward to engage the brake pads, then effective retraction force is applied, but the spring may enter the enclosed volume and contact the rotor
Solution Approach 1:
The stop surface is pre-positioned to exert a preliminary counteracting force that prevents the pad retraction spring from moving radially inward beyond a safe limit. This preliminary anti-action counterbalances the spring's retraction force and prevents excessive radial displacement that could cause the spring to contact the rotor, while still allowing the spring to apply sufficient retraction force to reduce rotor drag.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces rotor drag, minimizes wear on brake pads and rotors, and enhances fuel efficiency by actively retracting brake pads without additional components, while maintaining a compact and symmetrical design for ease of assembly and manufacturing.
Implementation Method 1
a pad retraction spring having a first supporting portion, a first engaging portion and a second engaging portion... the pad retraction spring urging the first and second brake pads in a direction away from the rotor plane
Data Source
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AI summary
A brake assembly for a heavy duty vehicle comprises a brake carrier, a caliper (102) that is mounted to the brake carrier, a first brake pad (103a) that is received in the brake carrier, the first brake pad comprising a first backplate (109a) and a first friction material (108a), a second brake pad (103b) that is received in the brake carrier, the second brake pad comprising a second backplate (109b) and a second friction material (108b), a pad retraction spring (104) having a first supporting portion(113), a first engaging portion (112a) and a second engaging portion(112b), and a first stop surface (106). The first friction material and the second friction material face each other and define a partially enclosed volume (110) therebetween for accommodating a brake rotor (140), the first stop surface (106) being located radially outward of the partially enclosed volume (110), wherein a rotor plane is disposed between the first brake pad and the second brake pad. The first backplate comprises a first backplate face (109a) and the second backplate comprises a second backplate face (109b), the first and second backplate faces facing the rotor plane. The first engaging portion (112a) of the pad retraction spring (114) engages the first backplate face (109a) and the second engaging portion (112b) of the pad retraction spring (114) engages the second backplate face (109b), the pad retraction spring (114) urging the first and second brake pads (103a, 103b) in a direction away from the rotor plane, wherein the first supporting portion (113) is configured to abut the first stop surface (106) such that the pad retraction spring (104) is inhibited from entering the partially enclosed volume.