Coordinated Electric Transaxle Shifting for Smooth Work Vehicle Traction
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Solution Overview
Problem
Large-scale work vehicles face challenges in efficiently transmitting power to all wheels or tracks, particularly when transitioning between different terrains and load conditions, which conventional diesel engines struggle to address effectively.
Innovation Solution
A work vehicle equipped with two electric transaxles, each with its own electric machine and transmission, mechanically uncoupled and controlled by a controller that determines coordinated shift sequences based on sensors detecting speed, heading, and loading characteristics to optimize gear shifts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple electric transaxles are used to provide high torque drives to all wheels, then power transmission efficiency and tractive force are improved, but device complexity and control difficulty increase
Solution Approach 1:
The power transmission system is divided into multiple independent electric transaxles, each serving specific wheels. This segmentation allows each transaxle to operate independently with its own electric machine and transmission, simplifying the control of each unit while achieving complex overall power distribution across multiple wheels for high torque drives
Solution Approach 2:
The patent replaces conventional mechanical coupling between transaxles with electronic control coordination. The controller electronically coordinates shift operations between multiple electric transaxles based on sensor inputs, eliminating complex mechanical linkages while maintaining synchronized power transmission efficiency across all wheels
2Ease of operation
If coordinated shift sequences are implemented based on sensor input, then gear shift smoothness and performance are improved, but control system complexity increases
Solution Approach 1:
The control system continuously receives feedback from sensors monitoring vehicle speed, acceleration, and operating conditions. This feedback enables the controller to dynamically adjust coordinated shift sequences for multiple electric transaxles, ensuring smooth gear transitions while adapting to real-time performance requirements without excessive complexity
Solution Approach 2:
The controller pre-coordinates shift timing between multiple electric transaxles based on predicted operating conditions and current sensor data. By planning shift sequences in advance rather than reacting to each condition change, the system achieves smooth gear transitions while reducing the computational complexity of real-time control
Data Source
AI summary
A work vehicle has two transaxles carried by a chassis each having wheel end units rotatable to drive ground-engaging members about wheel axes and having electric machines powering transmission configured to effect multiple gear ratios. The electric transaxles are operationally mechanically uncoupled. One or more sensors detect speed, heading, and loading characteristics of the work vehicle. A controller, having memory and processing architecture, is configured to process control to: receive from the one or more sensors input of the speed, heading, and loading characteristics of the work vehicle. The controller determines a shift pair sequence for shifting the first transmission and the second transmission based on the received input of the speed, heading, and loading characteristics of the work vehicle. The shift pair sequence defines a shift time (tS1) for shifting the first transmission and a shift time (tS2) for shifting the second transmission in which the shift time tS1 is the same or different than the shift time tS2. The controller generates a first shift command to shift the first transmission at the shift time tS1 while the second electric transaxle drives the work vehicle and generate a second shift command to shift the second transmission at the shift time tS2 while the first electric transaxle drives the work vehicle.