Hydraulic Anti-Stall Control for Low-Powered Open-Circuit Engines
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Solution Overview
Problem
Low-powered engines in hydraulic systems are prone to stalling due to high torque loads, and existing anti-stall systems, such as PID control and non-feedback proportional hydraulic control, are inadequate in preventing stalls, especially in mechanically controlled engines with limited power and complex operational variables.
Innovation Solution
An anti-stall system utilizing a combination of algorithms and sensors to dynamically adjust flow and pressure, including a reactive block, proactive block, flow-sharing block, and auxiliary block, to prevent engine stalling by monitoring torque loads and issuing commands to maintain optimal engine speed and reduce torque increases, thereby enhancing stability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a low-powered engine is coupled with a hydraulic system that can readily request too much torque, then the hydraulic system has higher installed capacity, but the engine droops and a stall occurs
Solution Approach 1:
The control system proactively monitors engine speed and hydraulic demand before a stall occurs, and preemptively adjusts pump flow or engages the auxiliary power source to prevent the stall condition from developing. This anticipatory control prevents the engine droop that leads to stalling.
Solution Approach 2:
An auxiliary power source (such as an electric motor or hydraulic motor) is introduced as an intermediary to assist the low-powered engine during high-demand situations. This additional power source prevents engine stalls by compensating for torque deficits without requiring the engine itself to be oversized.
2Reliability
If PID control is used to reduce stalls by controlling flow output, then stall occurrences are reduced, but the reactive nature of PID control has inherent inability to prevent stalls in many instances
Solution Approach 1:
The control system continuously monitors engine speed and hydraulic system demand to predict potential stall conditions before they occur. By taking preliminary action to adjust pump flow or engage auxiliary power sources, the system prevents stalls rather than merely reacting to them, eliminating the time delay inherent in reactive PID control.
Solution Approach 2:
The control system dynamically adjusts its response based on real-time engine speed and load conditions, transitioning from static PID parameters to adaptive control that can prevent stalls across varying operating conditions. This dynamic approach allows the system to respond appropriately to different stall risk scenarios.
3Ease of operation
If NFPH control is used in closed-loop pumps, then pump displacement is controlled, but stalls cannot be prevented but only limited
Solution Approach 1:
An auxiliary power source serves as an intermediary between the pump and the engine, providing additional torque when the engine approaches stall conditions. This allows the NFPH control to continue operating the pump while the auxiliary power source prevents the engine from stalling, thereby maintaining both ease of operation and stall prevention.
Solution Approach 2:
The control system monitors engine speed and hydraulic demand parameters, and when a stall is imminent, it changes the operational parameters by engaging the auxiliary power source or adjusting pump flow commands. This parameter change transitions the system from a control mode that only limits stalls to one that actively prevents them.
4Reliability
If engine torque limiting system is implemented, then stalls are limited, but numerous parts are required resulting in high manufacturing costs
Solution Approach 1:
The control system is designed to perform multiple functions: it monitors engine speed, controls pump flow, detects stall conditions, and manages auxiliary power source engagement. By making the control system universal and multi-functional, the patent avoids adding separate torque limiting hardware, thereby reducing device complexity while maintaining stall prevention capability.
Solution Approach 2:
The patent replaces mechanical torque limiting devices (which would require numerous physical parts) with an electronic control system that manages torque and power distribution through software and electronic signals. This substitution of mechanical systems with electronic control reduces the number of physical parts required while achieving the same stall prevention function.
Data Source
AI summary
An anti-stall system to prevent an engine, particularly a low-powered engine, from stalling when encountering a load that the machine is capable of overcoming but due to the nature of the engine, the load encounter would result in a stall. The system includes a hydraulic system in communication with a control system that has one or more sensors that detect, determine, and/or transmit an operational variable. The control system further comprises a plurality of anti-stall blocks having unique configurations, including a first configured to limit output flow upon determination of an engine droop, a second configured to limit output flow based on available engine torque, a third configured to limit output pressure upon rapid engine droop detection, and a fourth configured to prioritize and share output flow between the machine functions. The anti-stall blocks provide for complementary and cooperative configuration to prevent a stall from occurring based on responses to the detection and determination of various dynamic and continuous operational variables in real-time or near real-time with operational parameters.