Tooth-Driven Brake Clutch Mechanism for Precise Over-Torque Protection
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Solution Overview
Problem
Conventional over-torque protection devices in brake systems, such as wrap spring clutch and ball ramp mechanisms, are prone to over-slipping, under-slipping, and complexity, leading to brake failure and high manufacturing costs.
Innovation Solution
A tooth-driven over-torque protection mechanism featuring a shaft with toothed gear and a spring-loaded cam clutch device that transfers torque via tooth-to-tooth interaction, preventing over-slipping and allowing controlled torque transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wrap spring clutch or ball ramp mechanism is used for over-torque protection, then torque transmission is enabled, but over-slipping or under-slipping occurs leading to brake failure
Solution Approach 1:
The patent replaces the friction-based wrap spring clutch mechanism with a tooth-driven positive engagement mechanism. The drive gear engages with the clutch gear through interlocking teeth, eliminating reliance on friction coefficients and spring tension variations that cause slipping. This mechanical substitution ensures precise torque transmission without over-slipping or under-slipping, directly resolving the reliability and operational accuracy contradiction.
Solution Approach 2:
The invention changes the fundamental parameter of torque transmission from friction-based (wrap spring) or ball-ramp based to tooth-based positive engagement. By altering the transmission mechanism parameter, the system achieves deterministic torque transfer where the tooth profile and engagement geometry precisely control torque limits, eliminating the variability and imprecision inherent in friction and spring-based systems.
2Reliability
If wrap spring clutch or ball ramp mechanism is used for over-torque protection, then torque limiting is achieved, but device complexity increases and manufacturing costs rise
Solution Approach 1:
The clutch assembly is segmented into distinct functional components: a drive gear with external teeth, a clutch gear with internal teeth, and a simple release mechanism. This segmentation allows each component to be manufactured independently using standard gear machining processes, reducing overall complexity compared to the integrated wrap spring or ball ramp assemblies. The modular design simplifies both manufacturing and maintenance.
Solution Approach 2:
The tooth-driven clutch mechanism uses simple, robust components that can be manufactured at low cost using conventional machining. The gear teeth and basic release mechanism are far less complex and expensive than precision-wound wrap springs or precision-machined ball ramps. This approach prioritizes cost-effective, easily replaceable components over complex, expensive mechanisms.
3Measurement precision
If wrap spring clutch or ball ramp mechanism is used for over-torque protection, then torque control is provided, but tight tolerancing is required increasing manufacturing difficulty
Solution Approach 1:
The patent substitutes the tolerance-sensitive friction and spring-based torque control with a tooth-driven positive engagement system. Torque control is achieved through the inherent geometry of the gear teeth and their engagement, rather than relying on precise control of friction coefficients, spring rates, or clearance dimensions. This mechanical substitution dramatically reduces tolerancing requirements while maintaining precise torque control.
Solution Approach 2:
The invention changes the torque control parameter from friction coefficient and spring tension (which require tight tolerances) to gear tooth engagement geometry. The torque limit is determined by the tooth profile, number of teeth, and engagement depth - parameters that are more robust to manufacturing variations and can be controlled with standard machining tolerances, thereby reducing manufacturing precision requirements.
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 mechanism effectively prevents over-torquing without slipping, is easier to manufacture and service, less prone to failure, more accurate, versatile, and offers a compact, robust, and cost-effective solution compared to conventional systems.
Implementation Method 1
a first spring that biases the toothed gear against the clutch device
Implementation Method 2
a second spring that biases the clutch device against the toothed gear
Implementation Method 3
cam teeth that cooperate with the second teeth set of the toothed gear, such that a torque applied to the toothed gear is transmitted to the clutch device
Data Source
AI summary
A tooth driven over-torque protection mechanism for use in a slack adjuster or as an air disc brake clutch, includes a shaft, toothed gear, a clutch device, a first spring, and a second spring. The toothed gear is disposed on the shaft. The toothed gear has a first pinion teeth set that extends along a first direction and a second teeth set that extends along a second direction. The clutch device that is also disposed on the shaft and includes an upper cam and a lower cam. The first spring biases the toothed gear against the clutch device. The second spring biases the clutch device against the toothed gear. The upper cam has cam teeth that cooperate with the second teeth set of the toothed gear in a torque transmitting manner, such that a torque applied in a clockwise direction to the first pinion teeth is transmitted to the upper cam through the second teeth set, but torque applied in a counterclockwise direction is opposed by the first spring.