Vehicle Actuator Force Measurement via Spring and Micro Switch
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Solution Overview
Problem
Existing actuators for motor vehicle parking brakes face challenges in accurately monitoring braking force, leading to inadequate braking action and potential overloading of mechanical components, with existing force measurement methods being either inaccurate or costly.
Innovation Solution
An actuator design that incorporates a force transmission unit with a spring-based force measurement device and micro switches, allowing for direct detection of actuating force without the need for complex conversion, using a first and second spring to define distinct force values and a micro switch for precise control, eliminating the need for expensive displacement sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If indirect force measurement through current measurement of an electric motor is used, then the device complexity is reduced, but the measurement precision deteriorates
Solution Approach 1:
The patent replaces indirect electrical measurement (current measurement) with direct mechanical measurement using a spring element and displacement sensor. The spring mechanically converts force into displacement, which is then directly measured by a displacement sensor, eliminating the need for complex current-to-force conversion algorithms and improving measurement accuracy.
Solution Approach 2:
The patent introduces a spring element as an intermediary between the force transmission unit and the measurement system. The spring mechanically transduces the actuating force into a measurable displacement, serving as a mediator that directly links the force to be measured with the displacement sensor, thereby achieving precise force measurement through a simple mechanical relationship.
2Measurement precision
If a Hall sensor is used for excursion measurement, then the measurement precision is improved, but the device complexity and cost increase
Solution Approach 1:
The patent employs a displacement sensor that is simpler and more cost-effective than a Hall sensor, while maintaining adequate measurement precision. The displacement sensor directly measures the position of the stop element without requiring magnetic fields or complex signal conversion, thereby reducing device complexity and cost while still achieving the required measurement accuracy for force monitoring.
Solution Approach 2:
The patent replaces the magnetic-based Hall sensor measurement system with a direct mechanical displacement measurement system. The displacement sensor mechanically tracks the position of the stop element, eliminating the need for magnetic fields, signal amplification, and complex evaluation units, thereby simplifying the overall device while maintaining measurement precision.
3Ease of manufacture
If the switching travel of the micro switch is smaller than the measuring travel of the force transmission unit, then the ease of manufacture is improved, but the device complexity increases due to resilient support requirements
Solution Approach 1:
The patent makes the stop element dynamically resilient rather than rigidly fixed, allowing it to move and absorb the difference between the micro switch's small switching travel and the force transmission unit's larger measuring travel. This dynamic resilient support enables the use of compact micro switches while maintaining accurate force measurement across the full measuring range.
Solution Approach 2:
The patent changes the mechanical parameter of the stop element from rigid to resilient, allowing it to elastically deform and accommodate the travel difference. This parameter change enables the integration of micro switches with small switching travels into a system with larger measuring travels, simplifying manufacturing while managing the additional complexity through a single resilient component.
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 solution provides a simple, cost-effective actuator that accurately monitors and controls braking force, preventing overloading and ensuring reliable operation of the parking brake, with the ability to detect two distinct force values for precise switching points, thereby enhancing the actuator's operational efficiency and safety.
Implementation Method 1
The spring can be tensioned under the action of the actuating force by a first resilient excursion
Data Source
AI summary
An actuator for a motor vehicle functional unit includes a force transmission unit transmitting an actuating force to an actuating member and being displaced by a measuring travel in a force transmission direction. A force measurement device detects an actual value of the actuating force and includes a spring acting in the force transmission direction, having resilient action counter to which the force transmission unit is displaced and being tensioned by the actuating force over a resilient excursion, a micro switch having smaller switching travel than the measuring travel and being actuated upon displacement of the force transmission unit if the actuating force reaches the actual value, and a stop element for actuating the switch. The switch or element are coupled to or fixed relative to the force transmission unit and the switch and/or element are resiliently supported to compensate for a difference between the switching and measuring travels.