Compact Sealing Arrangement for Sliding Caliper Guide Pins
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Solution Overview
Problem
Sliding caliper disc brakes face challenges in providing effective sealing for guide pins due to limited space, leading to water and dirt ingress, corrosion, and increased frictional resistance, especially with the short guide pin where traditional sealing methods fail to maintain a reliable seal during caliper movement and pad wear.
Innovation Solution
A compact sealing arrangement featuring an elastomeric collapsible sealing boot with a caliper sealing end portion, a guide pin sealing end portion, and a retaining clip that holds the sealing bead within an axial bore of the guide pin, along with an integral retainer fixed to the guide pin, ensuring a secure and effective seal at both ends of the guide pin, even in tightly spaced caliper configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a protective cap is provided over the entire bore to seal the guide pin, then dirt ingress is prevented, but the caliper cannot move axially to adjust for pad and disc wear
Solution Approach 1:
The sealing system is divided into two separate sealing arrangements: one at the inboard end of the guide pin and another at the outboard end. This segmentation allows each seal to be optimized independently, with the outboard seal using a collapsible boot that accommodates caliper movement while maintaining sealing effectiveness.
Solution Approach 2:
The elastomeric collapsible boot is designed to dynamically change its configuration - collapsing when the caliper moves axially for wear adjustment, and expanding to maintain sealing when the caliper is in its normal position. This dynamic behavior resolves the contradiction between sealing and movement capability.
2Object-affected harmful factors
If a wiper seal is used on the short guide pin to limit dirt ingress, then some sealing is achieved, but frictional resistance increases and corrosion is not prevented
Solution Approach 1:
An elastomeric collapsible boot (flexible shell) is used instead of a rigid wiper seal. The boot forms a flexible barrier that prevents dirt ingress while accommodating the movement and shape changes of the guide pin, reducing frictional resistance compared to traditional wiper seals.
3Object-affected harmful factors
If a rolling boot with metal retaining ring is used to seal the short guide pin, then sealing is improved, but the retaining ring is prone to corrosion and the sealing bead can come loose
Solution Approach 1:
The sealing boot uses composite construction with an elastomeric body and a thermoplastic sealing bead. The thermoplastic material provides enhanced mechanical strength and corrosion resistance compared to traditional metal retaining rings, while the elastomeric portion maintains flexibility and sealing effectiveness.
Solution Approach 2:
The sealing bead is nested within the elastomeric boot structure, with the thermoplastic bead positioned to engage with the guide pin surface. This nested configuration allows the sealing bead to be securely retained without requiring a separate metal retaining ring that is susceptible to corrosion.
4Object-affected harmful factors
If the caliper is sealed at the outboard end with a rubber boot, then effective sealing is achieved, but there is not enough space in tightly spaced configurations
Solution Approach 1:
The elastomeric collapsible boot is designed to dynamically change its configuration - collapsing when the caliper moves axially for wear adjustment, and expanding to maintain sealing when the caliper is in its normal position. This dynamic behavior resolves the contradiction between sealing and movement capability.
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 provides a reliable and compact seal that minimizes corrosion, reduces frictional resistance, and maintains seal integrity during caliper movement, enhancing the service life and reliability of the sliding caliper disc brake, particularly for the short guide pin where space constraints were previously a barrier.
Implementation Method 1
an elastomeric collapsible mid portion
Implementation Method 2
The sealing system relies on a frictional press fit between the outer surface of the retaining ring and the inner surface of the counterbore to prevent the retaining ring from coming loose
Data Source
AI summary
Sealing means are disclosed for preventing the ingress of water and dirt between a brake caliper and the carrier guide pin. At the end of the guide pin facing away from the brake carrier, a retaining clip holds a sealing bead of a sealing boot at least partially within an axial bore of the guide pin. At the end of the guide pin which faces towards the carrier, a sealing boot is provided seated on a ring which in turn is attached to the caliper. The other end of the sealing boot is attached to the guide pin, in a space between the guide pin and the ring. The sealing means at either end are compact, and provide effective sealing where there is not enough space to provide known sealing means.