Work Vehicle Engine Output Control for Rotation Speed Stability
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Solution Overview
Problem
When the torque at the maximum horsepower point is set to be relatively high, the line connecting the maximum torque point and the maximum horsepower point is less inclined, leading to a weaker force acting to reset the engine rotation speed to the target rotation speed, making it difficult to suppress engine rotation speed decreases.
Innovation Solution
A work vehicle with an engine output control unit that sets a target rotation speed using a first engine output torque curve and detects the actual rotation speed, temporarily outputting torque greater than defined by the first curve to maintain engine rotation speed, and optionally switching to a second engine output torque curve when the actual rotation speed falls below the target.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the torque at the maximum horsepower point is set to be relatively high, then the maximum horsepower is increased, but the line connecting the maximum torque point and the maximum horsepower point becomes less inclined, making it difficult to suppress engine rotation speed decreases
Solution Approach 1:
The patent applies dynamics by switching between two different engine output torque curves (first and second curves) based on the actual engine rotation speed. When the rotation speed drops below the target, the system dynamically transitions from the first torque curve to the second torque curve, which has a steeper inclination, thereby dynamically adjusting the torque characteristics to maintain rotation speed while preserving high maximum horsepower capability.
Solution Approach 2:
The patent changes the torque curve parameters by selecting different engine output torque curves based on operating conditions. The second engine output torque curve is specifically designed with a steeper inclination than the first curve, changing the torque-speed relationship parameters to provide stronger rotation speed recovery force when needed, while maintaining the high horsepower characteristic when operating at target speed.
2Power
If the torque at the maximum horsepower point is set to be relatively high, then the maximum horsepower is increased, but the force acting to reset the engine rotation speed back to the target rotation speed becomes weaker
Solution Approach 1:
The system dynamically switches between torque curves based on rotation speed conditions. The second torque curve is activated when rotation speed drops, providing a steeper torque characteristic that generates stronger restoring force to bring the engine back to target rotation speed, while the first curve maintains high horsepower at normal operating conditions.
Solution Approach 2:
The patent changes the torque curve parameters by switching from the first engine output torque curve to the second engine output torque curve when rotation speed drops below target. The second curve is specifically designed with higher torque at the actual rotation speed, changing the force characteristics to provide stronger rotation speed recovery without sacrificing maximum horsepower capability.
Data Source
AI summary
An engine output control unit of a work vehicle is configured to set a target rotation speed of an engine by using an engine output torque curve, to control an output of the engine. The engine output control unit is configured to control the output of the engine so as to set torque to be higher than torque at an actual rotation speed obtained using the engine output torque curve. Typically, when the actual rotation speed of the engine becomes smaller than the target rotation speed, the engine output control unit sets an engine output torque curve that is greater in torque at the actual rotation speed than the engine output torque curve, and switches control of the output of the engine from control performed using the engine output torque curve to control performed using the engine output torque curve.