Hold-Down Spring Geometry for Commercial Vehicle Brake Stress Reduction
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Solution Overview
Problem
Conventional caliper disc brakes for commercial vehicles face mechanical stress and asymmetrical design requirements due to the hold-down spring's construction, leading to unfavorable loading and increased complexity in manufacturing and installation.
Innovation Solution
The hold-down spring is redesigned with two identical spring legs and a trapezoidal central region, featuring angles greater than 95° and less than 85°, along with arcuate transitions, to reduce mechanical stress and allow for symmetrical installation, enabling a more versatile and economical design that minimizes mechanical stress and simplifies manufacturing by using a single mold for both left and right brakes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the hold-down bracket is offset by an axis offset in the direction of rotation when driving forwards, then tangential preload is generated on the brake lining, but the brake caliper requires asymmetrical casting formations and mechanical processing, increasing device complexity and manufacturing difficulty
Solution Approach 1:
The patent applies asymmetry by deliberately offsetting the hold-down bracket's axis from the brake disc's center axis in the direction of rotation when driving forwards. This asymmetric positioning creates the necessary tangential preload on the brake lining while accepting the resulting asymmetrical casting formations in the brake caliper as a trade-off for achieving the required force distribution.
2Force
If the hold-down bracket is offset by an axis offset, then tangential preload is generated, but different casting patterns are required for left and right brakes, increasing manufacturing complexity
Solution Approach 1:
The asymmetric offset of the hold-down bracket necessitates different casting patterns for left and right brakes. The patent accepts this manufacturing complexity as a required consequence of achieving the tangential preload function, with each brake requiring its specific asymmetric casting configuration.
3Force
If the hold-down spring is used with form-fitting engagement in the central region, then radial and tangential pretension is generated, but the spring is unfavorably loaded from a mechanical point of view
Solution Approach 1:
The patent applies local quality by creating a form-fitting engagement between the hold-down bracket and the hold-down spring in the central region. This localized geometric matching generates both radial and tangential pretension forces while distributing the mechanical loading more favorably across the spring structure, addressing the unfavorable loading condition through precise local geometry design.
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
This configuration reduces mechanical stress on the hold-down spring, simplifies the manufacturing process by allowing a single mold design for both left and right brakes, and enhances the brake's operational efficiency by avoiding adverse tangential preload on the rim-side brake pad.
Implementation Method 1
a hold-down spring (32) for holding down the power transmission element and a hold-down device (36) held and supported by a holding device (40) on the saddle (20), which radially preloads the hold-down spring (32) against the power transmission device
Implementation Method 2
preloads the hold-down spring (32) tangentially in the direction of rotation when driving forwards against the power transmission device
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A caliper disc brake of a vehicle, in particular of a commercial vehicle, with a brake disc having an axis of rotation, a brake caliper, a brake anchor plate, a force transmission element, such as, for example, a lining support and/or a pressure plate, which is guided and supported in a shaft of the brake caliper or of the brake anchor plate, a holding-down spring (32) for holding down the force transmission element, and a holding-down device (36) which is held and supported on the caliper by a holding device, pretensions the holding-down spring radially against the force transmission device and pretensions the holding-down spring tangentially in the direction of rotation against the force transmission device during forwards travel, wherein the holding device has a centre line lying parallel to the axis of rotation. The holding-down spring has two identical spring legs and a trapezoidal central region which is located in between and projects radially inwards, wherein the two legs of the trapezoidal region each enclose an angle of more than 95° with the base in the relaxed state and an angle of less than 85° with the respectively adjacent spring leg.