Motor Vehicle Drive Unit With Rolling Element for Low-Loss Actuation
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Solution Overview
Problem
Existing drive units for motor vehicle locking devices face inefficiencies in power transmission due to sliding friction between plastic and steel components, which hinders smooth operation and requires high torque from electric motors.
Innovation Solution
Incorporating a friction-reducing rolling element as an intermediate element between the drive element and actuating lever, with a rolling movement facilitated by an actuation ramp on an eccentric cam, reducing friction coefficients significantly compared to sliding friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If sliding friction contact is used between drive element and actuating lever, then structural simplicity is maintained, but power transmission efficiency deteriorates due to high friction coefficients
Solution Approach 1:
A rolling element is introduced as an intermediary component between the drive element and actuating lever. This rolling element mediates the power transmission by converting sliding friction contact into rolling contact, thereby significantly reducing friction coefficients and improving power transmission efficiency while maintaining structural simplicity
Solution Approach 2:
The friction parameter is changed by transitioning from sliding friction to rolling friction through the introduction of the rolling element. This parameter change reduces the friction coefficient from typical sliding friction values (0.3-0.6 for plastic-steel contact) to rolling friction values (0.001-0.01), thereby improving power transmission efficiency
2Force
If high torque is provided to overcome sliding friction, then actuating force is sufficient, but motor size and weight increase
Solution Approach 1:
The rolling element acts as a mediator that reduces the frictional resistance between drive element and actuating lever. This reduction in friction allows the motor to generate sufficient actuating force with lower torque output, enabling the use of smaller, lighter motors while maintaining adequate actuating force
3Ease of manufacture
If plastic cam and steel actuating lever are used for sliding friction contact, then manufacturing is simplified, but power transmission loss increases
Solution Approach 1:
The rolling element serves as an intermediary between the plastic cam and steel actuating lever, converting their sliding friction contact into rolling contact. This maintains the manufacturing simplicity of using plastic and steel components while dramatically reducing power transmission loss through the low-friction rolling interface
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 design achieves low-loss power transmission with reduced rolling resistance, enabling a low-force electrical operation of motor vehicle locking devices and other applications, allowing for the use of smaller electric motors with cost and weight advantages.
Implementation Method 1
a rolling movement, and consequently rolling friction, occurs between the drive element and the actuating lever actuated by the drive element due to the rotatably mounted intermediate element or friction-reducing rolling element arranged therebetween
Data Source
Figure 1
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Figure 3A~3B
AI summary
The invention relates to a drive unit for motor vehicle applications, in particular motor vehicle closing devices. The drive unit comprises an electric motor (4) and at least one drive element (5) driven by the electric motor (4). In addition, an actuation lever (7) that cooperates with the drive element (5) is provided. The drive element (5) and/or the actuation lever (7) are advantageously designed to be able to rotate about an axis (6, 8). A rotatably mounted intermediate element (9) is provided between the drive element (5) and the actuation lever (7). According to the invention, the intermediate element (9) is in the form of a friction-reducing rolling element (9).