Engine Speed Control Using Lower Stabilization Speed Under Load
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Solution Overview
Problem
Conventional engine controllers in power machines struggle to maintain optimal power delivery during high-load operations, often resulting in engine droop and suboptimal performance due to their focus on maintaining a target operational speed, which can lead to unpredictable stabilization behavior and limited drive speed even when overall power demand is low.
Innovation Solution
Implementing a control system that allows the engine to operate at a target stabilization speed lower than the target operational speed, by modifying operator inputs and controlling work element loads, to optimize power delivery to tractive elements, thereby managing engine speed and torque more effectively during high-demand conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the engine controller maintains target operational speed during high-load operations, then engine speed stability is improved, but power delivery to drive system deteriorates
Solution Approach 1:
The system dynamically adjusts the target engine speed based on operating conditions. During high-load operations, the controller allows the engine to operate at a stabilized speed lower than the nominal target speed, optimizing power delivery to the drive system while maintaining acceptable speed stability. This dynamic adjustment resolves the contradiction by making the speed target flexible rather than fixed.
Solution Approach 2:
The controller changes the target speed parameter from a fixed value to a variable that adapts to load conditions. By modifying the target speed parameter downward during high-demand operations, the system prioritizes power delivery over strict speed maintenance, resolving the contradiction between speed stability and power delivery.
2Speed
If the engine controller attempts to recover from engine droop by adjusting engine torque, then engine speed recovery is improved, but drive system power delivery deteriorates
Solution Approach 1:
Instead of increasing torque to recover engine speed (conventional approach), the system inverts the strategy by allowing the engine to stabilize at a lower speed and modulating the work element load downward. This reverse approach prioritizes power delivery to the drive system while maintaining acceptable engine operation, resolving the contradiction between speed recovery and power delivery.
Solution Approach 2:
The system applies partial action by not fully attempting to recover to the nominal target speed during droop conditions. Instead, it accepts a stabilized speed below the target and uses partial load modulation on work elements to maintain optimal power delivery, resolving the contradiction by avoiding excessive torque application.
3Speed
If the controller modulates work element load to maintain engine speed, then engine speed control is improved, but overall power delivery to drive system deteriorates
Solution Approach 1:
The system inverts the conventional control approach by not prioritizing engine speed maintenance through work element load modulation. Instead, it allows the engine to operate at a stabilized lower speed and uses selective work element control to optimize power delivery to the drive system, resolving the contradiction by reversing the priority from speed control to power optimization.
Data Source
AI summary
A power machine can include an engine control module configured to determine a target operational speed of the power machine and control the engine based on the target operational speed. A drive controller can be configured to control operation of a hydraulic drive pump or other work element to decrease engine speed toward a target stabilization speed that is lower than the target operational speed.