Electrified Vehicle Drive Device Torque Imbalance Offset
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Solution Overview
Problem
The existing drive device for electrified vehicles experiences an unintended imbalance in drive torque between the right and left wheels due to loss torque from a common oil pump, which can lead to a deterioration in the vehicle's straightness.
Innovation Solution
The configuration includes two drive devices, one at the front and one at the rear, with each oil pump connected to different gear units, ensuring that loss torque is applied to wheels on opposite sides, thereby offsetting the torque imbalance and improving vehicle straightness. Additionally, the speed reduction ratios and oil pump sizes can be adjusted to match or approximate the torque imbalances between the front and rear wheels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a common oil pump is connected to one gear unit to perform oil circulation for both gear units, then the device complexity is reduced, but drive torque imbalance occurs between left and right wheels
Solution Approach 1:
The patent divides the single oil pump system into two separate oil pumps, with each pump connected to a different gear unit. This segmentation allows each gear unit to have its own dedicated oil circulation system, eliminating the torque imbalance caused by a common pump while maintaining manageable system complexity through modular design.
Solution Approach 2:
The patent applies local quality by making the oil pump configuration asymmetric - the first oil pump is connected to the first gear unit while the second oil pump is connected to the fourth gear unit. This localized differentiation ensures that loss torque is distributed to opposite sides (left front and right rear wheels), compensating for torque imbalance without requiring complete system symmetry.
2Device complexity
If loss torque from the oil pump is applied to only one gear unit, then the device complexity is simplified, but unintended torque imbalance occurs between drive torque transmitted to right and left wheels
Solution Approach 1:
The patent uses the loss torque from the second oil pump as a counterbalancing force to offset the torque imbalance caused by the first oil pump. By strategically connecting the second oil pump to the fourth gear unit (right rear wheel), the system creates an opposing torque effect that compensates for the imbalance at the front wheels, maintaining vehicle straightness through passive torque balancing.
Solution Approach 2:
The patent deliberately creates an asymmetric oil pump connection configuration where the first oil pump connects to the first gear unit and the second oil pump connects to the fourth gear unit. This asymmetric arrangement ensures that loss torques are applied to wheels on opposite sides, creating a balancing effect that maintains reliability and straightness without requiring symmetric system design.
Data Source
AI summary
The first drive device includes a first motor connected to the left front wheel via a first gear unit, and a second motor connected to the right front wheel via a second gear unit, and a first oil pump connected to the first gear unit or the second gear unit. The second drive device includes a third motor connected to the left rear wheel via a third gear unit, a fourth motor connected to the right rear wheel via a fourth gear unit, and a second oil pump connected to the third gear unit or the fourth gear unit. One of the first oil pump and the second oil pump is connected to the first gear unit or the third gear unit, and the other of the first oil pump and the second oil pump is connected to the second gear unit or the fourth gear unit.