Hydraulic Pump Controller for Engine Stall Prevention
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Solution Overview
Problem
Existing hydraulic systems face issues with engine stall due to excessive load from hydraulic pumps, leading to jerky operation and operator frustration, and current solutions are complex and costly.
Innovation Solution
A hydraulic system with a controller that determines a lug speed error and sets closed-loop gains to generate a pump control signal, reducing the load on the engine by scaling the error, thereby preventing stall and improving operational smoothness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an anti-stall valve is used to prevent engine stall, then engine stall is prevented, but the hydraulic circuit becomes complex and expensive
Solution Approach 1:
The patent extracts the anti-stall function from a complex hydraulic valve system and implements it through a simplified electronic control system. The controller monitors engine speed and directly controls the variable displacement pump to reduce load when stall conditions are detected, eliminating the need for complex anti-stall valves and associated hydraulic circuitry.
Solution Approach 2:
The patent replaces the mechanical hydraulic anti-stall valve system with an electronic control system. The controller uses electronic sensors to monitor engine speed and electronic actuators to control pump displacement, substituting mechanical hydraulic pressure control with electronic feedback control.
2Reliability
If total removal of hydraulic load is implemented, then engine stall is prevented, but jerky operation occurs causing operator frustration
Solution Approach 1:
The patent implements dynamic load control by continuously monitoring engine speed and adjusting pump displacement in real-time. When engine speed drops below a threshold indicating potential stall, the controller progressively reduces pump displacement to prevent stall while maintaining smooth operation. This dynamic adjustment prevents the abrupt load removal that causes jerky operation.
Solution Approach 2:
The patent uses feedback control where the controller continuously monitors engine speed and adjusts pump displacement based on the measured speed. The system compares actual engine speed with a target speed and modifies pump output accordingly, creating a smooth, continuous control loop that prevents both stall and jerky operation.
3Productivity
If variable displacement pump is used, then hydraulic power is optimized, but engine stall occurs due to excessive load
Solution Approach 1:
The patent implements preliminary protective action by monitoring engine speed continuously and detecting conditions that precede stall. When engine speed approaches a critical threshold, the controller proactively reduces pump displacement before stall occurs, preventing the harmful effect while maintaining optimal power utilization during normal operation.
Solution Approach 2:
The patent dynamically changes the pump displacement parameter based on engine operating conditions. During normal operation, the pump operates at high displacement for optimal hydraulic power. When engine speed indicates approaching stall conditions, the controller changes the displacement parameter to a lower value, reducing load and preventing stall.
Data Source
AI summary
A hydraulic system includes an engine; at least one hydraulic pump operatively coupled to the engine for transfer of mechanical power therebetween; and a controller operatively coupled to the engine and the at least one hydraulic pump. The controller is configured to determine a lug speed error as a difference between a target lug speed value and a speed of the engine, set at least one closed-loop gain to a non-zero value when the speed of the engine is less than the target lug speed value, and generate a pump control signal by scaling the lug speed error by the at least one closed-loop gain.