Spindle Actuator Rotational Play for Higher Axial Force
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Solution Overview
Problem
Existing electro-mechanical actuators for motor vehicle transmissions face challenges in generating sufficient actuation force, particularly at low temperatures, leading to increased fuel consumption, higher costs, and larger installation space requirements due to the need for high motor torque and power electronics.
Innovation Solution
An electro-mechanical actuator with intentional rotational play between the rotor and spindle drive, allowing for angular momentum transfer to increase actuation force, and a self-locking spindle drive to prevent loss of actuation travel, along with an electronic control unit for resetting and re-engaging the rotor within the rotational play.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the electro-mechanical actuator is designed for high actuating force at low temperatures, then sufficient actuation force is achieved, but the size of the electric machine and power electronics increases, leading to higher costs and increased installation space
Solution Approach 1:
The actuator utilizes periodic reset movements within the rotational play to build up angular momentum, which is then transferred to the spindle drive during actuation. This periodic action allows a smaller electric machine to generate sufficient actuating force by accumulating momentum over multiple cycles rather than requiring continuous high torque.
Solution Approach 2:
The system dynamically switches between reset mode (rotating within rotational play without load) and actuation mode (transferring momentum to the spindle). This dynamic operation allows the electric machine to operate at low power during resets and only consume high power briefly during momentum transfer, reducing overall size requirements.
2Force
If the electro-mechanical actuator is designed for high actuating force at low temperatures, then sufficient actuation force is achieved, but the size of the electric machine and power electronics increases, leading to higher costs
Solution Approach 1:
The periodic reset and actuation cycles allow the use of a smaller, less expensive electric machine that can generate high peak forces through momentum transfer rather than requiring continuous high power capability, thereby reducing overall system cost.
3Force
If rotational play is introduced between the rotor and spindle drive, then angular momentum can be transferred to increase actuation force, but the precision of the drive may be affected
Solution Approach 1:
The system dynamically manages the rotational play by using it intentionally for momentum accumulation during resets, then eliminating its effect during actuation through controlled momentum transfer. This dynamic approach converts what would normally be a precision error into a functional feature.
Solution Approach 2:
The rotational play, which would normally represent imprecision or backlash in the drive, is converted into a beneficial feature that enables angular momentum accumulation. The play allows the rotor to rotate freely during resets without loading the spindle, building up speed and momentum that is then transferred during actuation.
4Force
If the electro-mechanical actuator resets within rotational play to build momentum, then actuation force is increased, but the time required for reset and re-engagement may increase
Solution Approach 1:
The reset and actuation operations are structured as rapid periodic cycles. The reset phase builds momentum quickly within the rotational play limits, and the actuation phase transfers this momentum efficiently, creating a high-frequency oscillating pattern that minimizes total cycle time while achieving high peak forces.
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 solution provides a cost-effective and space-efficient means to generate increased axial actuation force, reducing the need for large electric machines and power electronics, while maintaining efficient power transmission and minimizing torque load on the driving toothing.
Implementation Method 1
the actuating force of the electro-mechanical actuator is increased relative to the size of the electro-mechanical actuator... due to the use of angular momentum
Implementation Method 2
a self-locking spindle drive is provided as the return travel interlock
Data Source
AI summary
An electro-mechanical actuator for generating an axial actuation force is provided. The electro-mechanical actuator includes an electric machine having a stator (1) and a rotor (2). The electro-mechanical actuator also includes a spindle drive with a rotary element (6) and with an element that is movable in a translatory manner. A rotation of the rotary element (6) may result in a translatory motion of the element that is movable in a translatory manner. The rotor (2) and the rotary element (6) of the spindle drive are coupled to each other in a circumferential direction (U) such that a rotation of the rotor (2) results in a rotation of the rotary element (6) of the spindle drive (5). A rotational play (8) is formed between the rotor (2) and the rotary element (6) of the spindle drive in the circumferential direction (U).