Brake Caliper Guide Pin Locking for Pad Clearance Control
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Solution Overview
Problem
Existing air-actuated heavy-vehicle disc brakes suffer from unintentional contact between brake pads and the rotor due to uneven rotor surfaces and engine vibrations, leading to increased wear and reduced efficiency, and existing positive pad retraction systems fail to account for differential wear and are difficult to align.
Innovation Solution
A brake assembly with a lock arrangement that inhibits relative sliding between the caliper and brake carrier using an expandable element or moveable element to maintain a desired running clearance and dampen vibrations, featuring a compact design that adjusts friction forces without additional gas supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the caliper is allowed to slide freely on guide pins relative to the brake carrier, then the brake pads can move to contact the rotor during braking operation, but the brake pads may contact the rotor unintentionally outside of braking operation due to engine vibration or cornering forces
Solution Approach 1:
The guide pin is designed with a tapered geometry where the diameter varies along its length, creating a dynamic clearance condition. During braking, the caliper slides freely along the guide pin. During non-braking operation, the caliper naturally positions itself at a specific location along the guide pin where the clearance is minimized, preventing unintentional pad contact with the rotor while maintaining braking effectiveness.
Solution Approach 2:
The guide pin's diameter parameter is changed along its length to create a tapered profile. This parameter variation establishes different clearance conditions at different positions of the caliper, allowing the system to automatically adjust between free sliding during braking and constrained positioning during non-braking operation, thereby preventing unintentional contact.
2Reliability
If existing positive pad retraction systems are used to push brake pads away from the rotor, then pad contact is prevented, but the systems are difficult to align and locate due to machining tolerances and cannot account for differential wear
Solution Approach 1:
The tapered guide pin creates a self-aligning mechanism where the caliper automatically positions itself at the optimal location along the guide pin based on the tapered geometry. This eliminates the need for complex external alignment systems and machining tolerances, as the geometry itself provides the positioning function. The system self-adjusts to account for differential wear between inboard and outboard pads.
Solution Approach 2:
Instead of using active mechanisms to push pads away from the rotor, the invention uses a passive geometric constraint where the tapered guide pin naturally limits caliper movement. The approach is inverted from active retraction to passive positioning, simplifying the system while maintaining effectiveness.
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
Prevents unintentional contact between brake pads and rotor, reduces wear, and enhances vehicle efficiency by maintaining consistent pad positioning and damping vibrations, while requiring minimal components and space.
Implementation Method 1
The first lock arrangement may be configured to increase a frictional force between the first lock arrangement and the other of the caliper or the first guide pin in a first state of the first lock arrangement relative to a second state of the first lock arrangement.
Implementation Method 2
the lock arrangement may also act to dampen undesirable vibrational effects, such as a rattling sound caused by the guide pin abutting against the caliper due to engine vibration for example.
Data Source
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AI summary
A brake assembly for a heavy commercial vehicle comprising a caliper (102) and a first guide bore (122a), a brake carrier (101) arranged to receive a brake pad; a first guide pin (126a) secured to the brake carrier, the first guide pin being received within the first guide bore (122a) of the caliper such that the caliper is slideable relative to the brake carrier, and a first lock arrangement (242) at least partially located within the first guide bore. The first lock arrangement is operable to selectively inhibit relative sliding between the caliper and the brake carrier.