Ball Ramp Brake Central Spring Return Mechanism
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Solution Overview
Problem
Prior ball ramp brakes face complexity and inefficiency due to multiple springs in the return mechanism and directional bias in braking torque, leading to uneven wear and reduced performance.
Innovation Solution
A ball ramp brake design featuring a central spring to provide axially aligned return force, eliminating the need for multiple springs and incorporating an annular roller bearing to prevent rotational torque transfer, ensuring consistent braking force regardless of shaft rotation direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple springs are used in the return mechanism, then the rotatable actuator can be returned to the unactuated state, but the device complexity increases and the return force becomes uneven
Solution Approach 1:
Multiple separate springs are merged into a single central spring that provides the return force. The patent replaces the plurality of outwardly spaced springs with one centrally located spring that acts on the rotatable actuator, simplifying the return mechanism while maintaining its functionality.
Solution Approach 2:
The return mechanism is segmented into a central spring component that works in conjunction with a cable assembly. The cable assembly is divided into a stationary portion and a rotatable portion, allowing the spring to act centrally while the cable transmits the force to rotate the actuator back to its unactuated position.
2Reliability
If multiple springs are used in the return mechanism, then the rotatable actuator can be returned to the unactuated state, but the manufacturing difficulty increases
Solution Approach 1:
Multiple separate springs are merged into a single central spring that provides the return force. The patent replaces the plurality of outwardly spaced springs with one centrally located spring that acts on the rotatable actuator, simplifying the return mechanism while maintaining its functionality.
3Ease of operation
If stationary discs are coupled to housing via pins with clearance, then the disc assembly can slide axially, but rotational feedback occurs causing directional bias in braking torque
Solution Approach 1:
A bearing is introduced as an intermediary element between the rotatable actuator and the disc assembly. This bearing prevents rotational feedback from the disc assembly from being transmitted back to the rotatable actuator, thereby eliminating the directional bias in braking torque while still allowing axial movement of the disc assembly.
4Force
If friction exists between rotatable actuator and stationary disc, then the actuator can apply axial force to the disc assembly, but braking efficiency is reduced due to force absorption
Solution Approach 1:
The bearing provides a controlled amount of rotational play that allows the rotatable actuator to rotate slightly without transferring excessive rotational friction to the disc assembly. This partial rotation capability reduces energy loss while still maintaining effective axial force transmission for braking.
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 central spring design simplifies the return mechanism, reduces wear, and eliminates directional bias, resulting in improved braking efficiency and consistent braking force across different rotation directions.
Implementation Method 1
a spring under compression positioned centrally about the axis and adapted to bias the rotatable actuator toward the housing
Implementation Method 2
an annular roller bearing positioned between the rotatable actuator and the disc assembly
Data Source
Figure 1
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AI summary
A brake (10) for applying a braking force to a shaft includes a housing (11) which defines a chamber (17). The housing (11) includes a plurality of depressions (19) which are circumferentially spaced around an axis (22). A rotatable actuator (40) is received in the chamber (17) and includes a plurality of depressions (43) circumferentially spaced around the axis (22). The housing depressions (19) face the rotatable actuator depressions (43) and each matching pair of depressions receive a ball (23) therebetween. A spring (50) under compression is positioned centrally about the axis (22). A bearing (56) is interposed between the rotatable actuator (40) and disc assembly (70). When the rotatable actuator (40) is rotated, the balls (23) roll along the depressions (19, 43) to gradually shallower portions thereof. This in turn moves the rotatable actuator (40) axially away from the housing (11), thereby applying a braking force to the shaft. The spring (50) compressively opposes the axial movement of the rotatable actuator (40) away from the housing (11). Further, the inclusion of the bearing (56) between the rotatable actuator (40) and the disc assembly (70) minimizes frictional effects and rotational feedback during brake actuation.