Work Vehicle Prime Mover Speed Control via Torque Converter Ratio
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Solution Overview
Problem
Existing prime mover control devices for work vehicles lack the ability to set a maximum engine speed suitable for varying traveling loads due to a lack of flexibility in engine speed limiting states.
Innovation Solution
A prime mover control device that includes a rotational speed control unit, a speed ratio calculation unit, and a rotational speed limit unit, which adjusts the maximum rotational speed based on the torque converter speed ratio, allowing for multiple operational modes to optimize engine speed according to load conditions, including limiting the speed when the speed ratio falls within specific ranges and increasing it when maintained within those ranges for predetermined times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the engine speed is significantly limited to reduce fuel consumption, then fuel efficiency is improved, but the engine cannot provide sufficient power for varying traveling loads
Solution Approach 1:
The patent applies dynamics by making the engine speed limit value changeable based on operating conditions. The control device dynamically adjusts the maximum engine speed according to the torque converter speed ratio, which reflects the current traveling load. When the speed ratio indicates heavy load, the limit is raised to provide sufficient power; when the load is light, the limit is lowered to reduce fuel consumption. This dynamic adjustment resolves the contradiction between fuel efficiency and adaptability.
Solution Approach 2:
The patent changes the parameter of engine speed limit value based on the torque converter speed ratio. By monitoring the speed ratio and adjusting the maximum engine speed accordingly, the system adapts to different traveling loads. The control device establishes a relationship between speed ratio ranges and corresponding speed limit values, allowing the engine to operate efficiently under light loads while providing adequate power under heavy loads.
2Device complexity
If a single state for relaxing the limit of maximum engine speed is used, then the control system is simple, but it is difficult to set a maximum engine speed suitable for different traveling loads
Solution Approach 1:
The patent segments the speed ratio range into multiple ranges, with each range corresponding to a different speed limit value. This segmentation allows the control system to provide differentiated engine speed limits for different traveling load conditions. The control device determines which range the current speed ratio falls into and applies the appropriate speed limit, enabling precise adaptation to varying loads while maintaining relatively simple control logic.
Data Source
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AI summary
A prime mover control device of a work vehicle equipped with a torque converter includes: a speed ratio calculation unit that calculates a speed ratio of the torque converter; and a rotational speed limit unit that, when a speed ratio falls within a preset speed ratio range, limits a maximum rotational speed of the prime mover to be lower as compared with a maximum rotational speed set when a speed ratio falls without the preset speed ratio range. When a state in which the speed ratio calculated by the speed ratio calculation unit falls within the preset speed ratio range is maintained for a predetermined time period, the rotational speed limit unit changes a maximum rotational speed of the prime mover to a higher maximum rotational speed than the limited maximum rotational speed limited to be lower by the rotational speed limit unit.