Electric Motor Brake Axial Length Reduction via Radial Sensor
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Solution Overview
Problem
The existing electric motor-driven brake apparatus tends to increase in size due to the axial arrangement of components like the ball ramp mechanism, thrust detecting sensor, and pad wear following mechanism, making it challenging for mountability onto vehicles.
Innovation Solution
The apparatus incorporates a transmission mechanism that converts rotational force into thrust using a screw mechanism with a non-rotatable nut member and a movable shaft member, allowing the caliper to support the pressing member axially, thereby reducing the overall size and improving mountability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ball ramp mechanism, thrust detecting sensor, and pad wear following mechanism are disposed along the axial direction, then the brake apparatus can achieve normal braking function, but the axial length increases making it unfavorable for mountability
Solution Approach 1:
The patent repositions the thrust detecting sensor from an axial arrangement to a radial arrangement. The sensor is disposed to detect thrust in the radial direction of the shaft member, allowing the sensor, ball ramp mechanism, and pad wear following mechanism to be arranged in different spatial dimensions rather than all along the axial direction. This dimensional reorganization reduces the axial length while maintaining all necessary braking functions.
2Reliability
If a traditional ball ramp mechanism with axial sensor arrangement is used, then the brake apparatus achieves reliable thrust detection, but the overall size increases reducing ease of installation
Solution Approach 1:
The thrust detecting sensor is configured to detect thrust in the radial direction rather than axially. The sensor includes a detection element that moves radially along the shaft member's circumference, allowing thrust detection functionality to be achieved with compact axial dimensions. This enables easier installation and integration into vehicle brake systems with limited space.
Solution Approach 2:
The shaft member serves multiple functions: it transmits rotational force from the motor, acts as a guide for the ball ramp mechanism, and provides a radial movement path for the thrust detecting sensor. This multi-functionality reduces the need for separate dedicated components, thereby reducing overall size and improving mountability.
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
This configuration effectively reduces the axial length of the brake apparatus, enhancing its mountability on vehicles while maintaining the functionality of the brake system.
Implementation Method 1
a screw mechanism converting the rotational force of the transmission mechanism into a thrust; The screw mechanism includes a nut member non-rotatably supported relative to the caliper, and a shaft member receiving rotational force from the transmission mechanism. The shaft member is movable relative to the nut member in an axial direction of the shaft member.
Data Source
AI summary
An electric motor-driven brake apparatus has speed reduction mechanisms transmitting rotational force of an electric motor, a ball screw mechanism converting rotational force of the speed reduction mechanisms into a thrust, a piston propelled by the ball screw mechanism, and a caliper movably supporting the piston. The ball screw mechanism has a base nut non-rotatably supported relative to the caliper. The ball screw mechanism further has a push rod receiving rotational force from the speed reduction mechanisms. The push rod is movable relative to the base nut in the axial direction of the push rod. Consequently, it is possible to reduce the axial length of the cylinder portion of the caliper body, and hence possible to attain a size reduction. Accordingly, it is possible to improve the mountability of the electric motor-driven brake apparatus 1 onto vehicles.