Electrohydraulic Axle Drive Layout for Flexible Torque Split
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Solution Overview
Problem
Commercial vehicles require space and weight-saving drive solutions that enable flexible drive torque control and are not dependent on internal combustion engines, as existing technologies face challenges in implementing powerful electric motors and efficient torque distribution.
Innovation Solution
An electro-hydraulic drive device with a purely electrically drivable axle and an electro-hydraulically drivable axle, featuring electric and hydraulic machines that form a compact structural unit, allowing for independent and variable drive torque distribution without an internal combustion engine, using hydraulic machines in fluid communication for power transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If wheel-mounted electric motors are used to enable flexible drive control, then drive flexibility is improved, but vehicle weight and space requirements increase
Solution Approach 1:
The drive system is segmented into multiple independent electric motor units, with each motor unit being capable of independent operation. This allows the system to provide flexible drive control by selectively engaging individual motors while maintaining lower overall weight compared to a single large motor system.
Solution Approach 2:
Each electric motor unit is designed to perform multiple functions: providing drive torque to wheels, serving as a generator during regenerative braking, and enabling independent wheel control. This multi-functionality reduces the need for additional components and minimizes overall system weight.
2Power
If powerful electric motors are installed to provide sufficient drive torque, then drive power is improved, but vehicle space requirements increase
Solution Approach 1:
The total drive power requirement is divided across multiple smaller electric motor units distributed at different wheel locations. This segmentation allows sufficient total power to be achieved while each individual motor unit occupies minimal space, avoiding the need for large centralized motor housing.
Solution Approach 2:
Instead of concentrating power in a single large motor along one dimension, the system distributes multiple motor units across different spatial dimensions (different wheels/axles). This dimensional distribution achieves the required total power output while optimizing space utilization throughout the vehicle structure.
3Adaptability or versatility
If hydraulic drive systems are used for torque distribution, then torque control flexibility is improved, but system complexity increases
Solution Approach 1:
A hydraulic fluid serves as an intermediary medium to transmit and distribute torque between electric motor units and wheels. This hydraulic intermediary enables flexible torque control and distribution while simplifying the mechanical connection architecture compared to direct mechanical gear systems.
Solution Approach 2:
The system employs hydraulic mechanisms (pistons, cylinders, hydraulic fluid) to achieve torque multiplication and distribution. The hydraulic approach provides smooth, continuous torque control with simplified mechanical linkages, reducing overall system complexity while maintaining high adaptability.
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
Enables flexible response to different driving situations, improves driving stability, and reduces reliance on internal combustion engines by providing a powerful and independent hydraulic drive train, suitable for commercial vehicles.
Implementation Method 1
Each of the two electric machines is designed as a wheel hub machine and is drive-connected to a wheel (9a-9f). Furthermore, the two electric machines can each be arranged at different wheel-side end regions of the corresponding axle and/or are designed as wheel hub machines.
Implementation Method 2
The first hydraulic machine is also in fluid communication with at least one hydraulic machine arranged on the electro-hydraulically driven axle for power transmission.
Data Source
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AI summary
The invention relates to an electro-hydraulic drive device (10) for a motor vehicle (20), preferably a commercial vehicle, comprising a purely electrically driven axle (A1) on which at least one electric machine (1a) is arranged, and an electro-hydraulically driven axle (A2) on which at least one hydraulic machine (2a) is arranged. Furthermore, the electro-hydraulic drive device (10) has a first electro-hydraulic drive unit (31) comprising a first electric machine (3e1) and a first hydraulic machine (3h1). The first hydraulic machine (3h1) is in drive communication with the first electric machine (3e1) for power transmission and in fluid communication with at least one hydraulic machine arranged on the electro-hydraulically driven axle (A2) for power transmission.This advantageously enables independent and variable provision of drive torques to the two axles (A1, A2), allowing for flexible responses to different driving situations. Furthermore, the invention also relates to a motor vehicle (20), preferably a commercial vehicle, with such an electro-hydraulic drive device (10).