Wheel Hub Drive Coupling to Cut Rotor Entraining Losses
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Solution Overview
Problem
Existing wheel hub drives for motor vehicles face inefficiencies due to permanent rotational connections between the rotor and the wheel hub, leading to increased energy losses and reduced electrical range.
Innovation Solution
A wheel hub drive system featuring a form-fit coupling device that can switch between a coupling state and a decoupling state, allowing the rotor to be connected to the wheel hub in a rotationally fixed manner for efficient energy transfer, and decoupling to prevent excessive entraining losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the rotor is permanently connected to the wheel hub in a rotationally fixed manner, then the wheel hub drive can provide continuous drive torque, but excessive entraining losses occur and energy efficiency decreases
Solution Approach 1:
The coupling device enables dynamic switching between connected and decoupled states. The actuating element can shift between a coupling position (engaging the toothing elements for rotationally fixed connection) and a decoupling position (disengaging to allow relative rotation). This dynamic capability allows the system to adapt to different operating conditions, preventing excessive entraining losses during coasting or regenerative braking while maintaining drive torque during acceleration.
Solution Approach 2:
The coupling device acts as an intermediary between the rotor and wheel hub. It includes a first coupling toothing element on the rotor and a second coupling toothing element on the wheel hub, with an actuating element that can engage or disengage these toothing elements. This intermediary mechanism provides controlled connection and disconnection, enabling the system to optimize energy efficiency without permanent rotational constraints.
2Use of energy by moving object
If the rotor is decoupled from the wheel hub to reduce energy losses, then energy efficiency improves, but the ability to transfer drive torque is interrupted
Solution Approach 1:
The system dynamically switches between decoupled and connected states based on operational requirements. During coasting or regenerative braking, the coupling device is in the decoupled state to minimize entraining losses and maximize energy efficiency. When drive torque is required, the actuating element shifts to the coupling position, re-engaging the toothing elements to ensure reliable torque transfer from the rotor to the wheel hub.
Solution Approach 2:
The control system monitors operational conditions and automatically actuates the coupling device based on detected needs. When the vehicle requires drive torque or experiences high wheel slip, the control system activates the actuating element to engage the coupling toothing elements, ensuring reliable torque transfer. This feedback mechanism maintains both energy efficiency and drive reliability without manual intervention.
3Productivity
If a form-fit coupling device is introduced to enable decoupling, then operational efficiency and range increase, but the device complexity increases
Solution Approach 1:
The coupling device serves as a controlled intermediary between the rotor and wheel hub. It comprises a first coupling toothing element on the rotor, a second coupling toothing element on the wheel hub, and an actuating element with defined positions. This structured intermediary mechanism provides reliable engagement and disengagement while maintaining a relatively simple overall design that integrates well within the existing wheel hub drive architecture.
Solution Approach 2:
The coupling device is segmented into distinct functional components: the first coupling toothing element, the second coupling toothing element, and the actuating element. This segmentation allows each component to perform its specific function efficiently while enabling modular manufacturing and assembly. The actuating element itself can be implemented through various simple mechanisms such as electromagnetic actuators, pneumatic cylinders, or mechanical linkages, keeping the overall complexity manageable.
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 system achieves a higher degree of efficiency, resulting in a significant range gain of several percentage points, and allows for a connectable and disconnectable all-wheel drive, enhancing energy savings and operational efficiency.
Implementation Method 1
an electric machine (30), having a stator (32) which is connected to the wheel carrier (20) in a rotationally fixed manner and a rotor (34), wherein the rotor (34) can be driven by means of the stator (32) and thus can be rotated in relation to the stator (32), in particular around an machine axis of rotation (36)
Data Source
AI summary
A wheel hub drive for a motor vehicle has a wheel carrier, a wheel hub rotatably mounted on the wheel carrier via a wheel bearing, to which wheel hub a vehicle wheel of the motor vehicle can be connected in a rotationally fixed manner, an electric machine which has a stator connected to the wheel carrier in a rotationally fixed manner and a rotor that can be driven via the stator and can thus be rotated in relation to the stator, which rotor is mounted rotatably on the wheel hub via a rotor bearing, and a form-fit coupling device which can be switched between a coupling state, in which the rotor is connected to the wheel hub in a form-fit and rotationally fixed manner by the coupling device, and a decoupling state, in which the rotor can be rotated in relation to the wheel hub.