Work Vehicle Transmission Segmentation and Control
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Solution Overview
Problem
Increasing the output of hydro-static mechanical transmissions on middle- or large-sized work vehicles while maintaining power transmission efficiency and reducing manufacturing costs, as well as addressing the complexity of controller operations for integrating signals from various transmission components.
Innovation Solution
A work vehicle configuration that combines the outputs of straight-traveling and turning system transmission paths using stepless transmission devices, with a control section that cooperatively controls these outputs, a detector for measuring actual values, and a control system that selects between instruction and measured values to optimize transmission settings, including the use of reverse and forward clutches for efficient power distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the capacity of the hydro-static mechanical transmission is increased to increase output, then the output is improved, but the size of the transmission increases and power transmission efficiency decreases
Solution Approach 1:
The transmission system is divided into two independent stepless transmission devices (first HST for straight-traveling, second HST for turning) that operate separately. Each device maintains its own optimal capacity and efficiency characteristics, avoiding the need to oversized a single transmission unit. The segmented architecture allows each component to be sized appropriately for its specific function while collectively delivering high total output.
2Power
If the capacity of the hydro-static mechanical transmission is increased to increase output, then the output is improved, but manufacturing costs increase
Solution Approach 1:
By segmenting the transmission system into two separate stepless transmission devices, each can be manufactured at a standard, optimized capacity rather than requiring a single large-capacity unit. This segmentation allows for economies of scale in manufacturing each individual device while achieving high total system output through their combined operation.
3Loss of energy
If a hydro-static mechanical transmission is used to improve power transmission efficiency, then efficiency is improved, but the transmission range in straight-traveling direction is limited
Solution Approach 1:
The system merges the functions of two stepless transmission devices, combining the straight-traveling force output from the first HST with the turning force output from the second HST. This combination through planetary gear mechanisms enables both high power transmission efficiency (inheriting from the HST design) and expanded transmission range (achieved through the differential turning capability that allows variable speed distribution between left and right wheels).
4Adaptability or versatility
If a controller integrates signals from multiple operation tools to control traveling operations, then control functionality is improved, but computation load increases and operability decreases
Solution Approach 1:
The control system automatically determines whether to use instruction values from operation tools or actually measured values from detectors based on the current operating state, without requiring complex manual intervention or high-speed computation. The system self-regulates by comparing operational context and selecting the most appropriate control data source, reducing computational burden while maintaining comprehensive control functionality.
Data Source
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AI summary
In a work vehicle such as a tractor, efficiency of a transmission path and operability can be enhanced while lighter weight and reduced cost can be achieved. The work vehicle includes an engine 5 mounted on a traveling body 2, a straight-traveling system transmission path including a first stepless transmission device 17, and a turning system transmission path including a second stepless transmission device 13, and is configured to combine an output of the straight-traveling system transmission path and an output of the turning system transmission path to drive left and right traveling units 3. The work vehicle also includes control sections 813 and 814 that control the output of the straight-traveling system transmission path and the output of the turning system transmission path in cooperation with each other; a transmission operation tool 822 that specifies the output of the straight-traveling system transmission path; and a detector 823 that detects the output of the straight-traveling system transmission path. The control sections 813 and 814 select one of an instruction value from the transmission operation tool 822 and an actually measured value from the detector 823 and sets the output of the turning system transmission path.