Off-Axis Electric Axle Layout for High-Ratio Compact Drive
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Solution Overview
Problem
Balancing compactness and high transmission ratio in industrial and commercial vehicle axles is challenging due to the need for robust designs and significant torques/powers, especially when integrating electric motors and transmissions.
Innovation Solution
An off-axis electric axle design with a planetary gearset and epicyclic gearing arrangement, where the electric motor is positioned opposite to the epicyclic gear train, allowing for compactness and high transmission ratios, and includes a differential and optional second electric motor with clutch systems for flexible torque distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a high transmission ratio is provided to achieve significant torques/powers, then the torque capability is improved, but the axle size and complexity increase
Solution Approach 1:
The patent implements nesting by placing the first electric motor within the differential housing, and positioning the planetary gearset such that its components are interlocked and space-efficient. The pinion is integrated with the first motor's output shaft, and the planetary gears are arranged to maximize space utilization within the compact axle assembly, achieving high transmission ratio without proportional increase in overall size
Solution Approach 2:
The patent transitions from traditional linear/axial arrangements to a three-dimensional off-axis configuration. The first electric motor is positioned off-coaxial with the differential, and the planetary gearset is arranged in a vertical dimension with the pinion above the planetary gears. This spatial reconfiguration allows high transmission ratio to be achieved through vertical stacking rather than horizontal expansion, reducing the axle's footprint
2Power
If two electric machines are used to achieve significant torques/powers, then the power capability is improved, but the device complexity increases
Solution Approach 1:
The patent merges the first electric motor with the differential assembly by integrating the motor within the differential housing and directly coupling its output shaft to the planetary gearset's pinion. This consolidation eliminates the need for separate mounting structures and simplifies the overall transmission arrangement, allowing dual motor configuration without linear increase in complexity
Solution Approach 2:
The planetary gearset serves multiple functions: it provides torque multiplication for the first electric motor, enables torque distribution between left and right wheels, and integrates with the differential mechanism for torque splitting. This multi-functionality reduces the need for additional components, allowing the system to achieve significant power capability without proportional increase in device complexity
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 achieves a compact and robust axle design capable of high transmission ratios, enabling efficient torque distribution and redundancy, ensuring operational reliability and energy efficiency, including high-torque starting and failure recovery functions.
Implementation Method 1
a planetary gearset, a first drive wheel configured to mesh with said pinion and operatively connected to an input port of the planetary gearset
Implementation Method 2
a second drive wheel, keyed to a third shaft, coaxial with the planetary gearset, meshing with the crown of the axle differential
Data Source
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AI summary
Electric axle for industrial or commercial vehicle comprising a differential (DF) equipped with an input port (K) and shafts for rotating an equal number of vehicle wheels (W), a first electric motor (E-motor 1) having a drive shaft on which a first pinion (P1) is keyed to transmit the motion to the input port (K) of the differential via at least one transmission (DL1) comprising, a first intermediate shaft (X1) is defined by a first group (G1) comprising an epicyclic gear train (EAX), a first transmission wheel (R1) configured to mesh with said first pinion (P1) in which the first transmission wheel (R1) defines a lying plane (LP) in which the first electric motor (E-motor 1) is arranged in a position opposite to the epicyclic gear train (EAX) with respect to the lying plane (LP).