Brake Torque Limiter Assembly for Asymmetric Piston Actuation
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Solution Overview
Problem
Existing brake systems face challenges in asymmetrically actuating pistons, leading to insufficient braking force and uneven wear due to symmetrical pressure application. Current solutions, such as limited slip differentials, require complex components, large packaging space, and intricate manufacturing processes.
Innovation Solution
The proposed brake system incorporates an electromechanical actuation system with a torque limiter assembly that includes a planetary gear, ring gear, pre-loaded member, and balls. This assembly sets a torque limit, allowing asymmetric actuation of pistons by transitioning from rotational captivity to freedom based on the engagement of balls with undulating surfaces on the ring gear and pre-loaded member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If symmetrical pressure is applied to the brake pad, then the brake system structure is simple, but insufficient braking force and uneven wear result due to asymmetric piston travel
Solution Approach 1:
The patent introduces a torque limiter assembly with asymmetric characteristics that allows different pistons to travel different distances. The torque limiter has a predetermined torque threshold that permits asymmetric piston movement when one piston encounters higher resistance, ensuring both pistons reach their required positions for uniform brake pad engagement while maintaining relatively simple overall system structure
2Ease of operation
If a limited slip differential is used to address asymmetric piston travel, then asymmetric actuation is achieved, but package space and parts complexity increase
Solution Approach 1:
The torque limiter assembly is segmented into distinct functional components: a torque limiter element with engagement features, a carrier with corresponding features, and a spring mechanism. This segmentation allows each component to perform its specific function while keeping the overall part count manageable and the assembly process straightforward
Solution Approach 2:
The torque limiter assembly acts as an intermediary mechanism between the motor and the pistons. It provides the necessary asymmetric actuation capability without requiring a complete redesign of the drive system, thereby adding functionality while minimizing increases in parts complexity
3Ease of operation
If a limited slip differential is used to address asymmetric piston travel, then asymmetric actuation is achieved, but packaging space requirements increase
Solution Approach 1:
The torque limiter assembly is designed to nest within the existing brake caliper structure. The torque limiter element, carrier, and spring are arranged in a compact configuration that fits within the available space, minimizing the increase in packaging volume while providing the necessary asymmetric actuation functionality
4Ease of operation
If limited slip differential systems are used, then asymmetric piston actuation is achieved, but manufacturing and assembly methods become more intricate
Solution Approach 1:
The torque limiter assembly uses a spring with a predetermined force characteristic and engagement features with specific geometric parameters that define the torque threshold. These parameters are designed to be straightforward to manufacture using conventional processes, avoiding the need for complex or specialized manufacturing and assembly methods
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 system effectively addresses asymmetric piston actuation by allowing the torque limiter assembly to set a specific torque limit, ensuring uniform load application to brake pads and reducing wear, while also minimizing the complexity and space requirements of the brake system.
Implementation Method 1
The spring may apply a force upon the pre-loaded member such that the balls are compressed between the pre-loaded member and the ring gear.
Implementation Method 2
At and above the torque limit, the balls may slip over the peaks, causing the ring gear to rotate and the planetary gear to remain orbitally captive.
Data Source
AI summary
A brake system comprising a torque limiter assembly that sets a torque limit and associated with an electromechanical actuation system. The torque limiter assembly comprises a ring gear meshed with two or more planetary gears, the ring gear comprising a first race extending circumferentially therearound. The torque limiter assembly comprises a pre-loaded member comprising a second race extending circumferentially therearound. Balls are engaged between the first and second races. The first and/or second races comprise a series of peaks and valleys, and slopes extending therebetween. Below the torque limit, the balls are engaged within the valleys causing the ring gear to remain rotationally captive and the planetary gears to orbit. At and above the torque limit, the balls slip over the peaks, causing the ring gear to rotate and the planetary gears to remain orbitally captive.