Hydrostatic Pump Torque Limiting for Engine Stall Prevention
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Solution Overview
Problem
Power machines with engine-powered hydraulic or hydrostatic drive systems face reduced efficiency and potential engine stalling due to excessive power loads during operations like digging or load carrying, as these systems often operate beyond the engine's optimal torque range.
Innovation Solution
Implementing an electronic control system that manages engine torque load by adjusting hydrostatic pump displacement based on engine torque data, using a torque limiting algorithm to constrain actuation signals and maintain operation within the engine's target torque range, thereby optimizing engine efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the hydrostatic drive system operates at high power loads during digging or load carrying operations, then the productivity and load carrying capacity are improved, but the engine torque load exceeds the optimal range causing reduced efficiency and potential engine stalling
Solution Approach 1:
The electronic control system continuously monitors engine torque load and uses this feedback to dynamically adjust pump displacement. The system compares actual torque load against target torque range and modifies pump displacement accordingly, creating a closed-loop control that maintains engine operation within the optimal torque range while accommodating varying load conditions
Solution Approach 2:
The system dynamically adjusts pump displacement in real-time based on changing operational conditions and engine torque load. Rather than using fixed pump displacement, the system continuously adapts the displacement parameter to match current engine conditions, enabling the drive system to maintain optimal efficiency across varying load scenarios
2Productivity
If the hydrostatic pump displacement is increased to meet high power demands, then the productivity is improved, but the engine torque load increases beyond the target torque output percentage
Solution Approach 1:
The system changes the physical parameter of pump displacement dynamically based on engine torque load conditions. By adjusting this key parameter in real-time, the system optimizes the balance between power delivery and engine efficiency, ensuring the engine operates at or near peak efficiency across varying operational demands
3Power
If the engine operates at maximum torque output to meet peak power demands, then the power availability is improved, but the engine efficiency decreases from optimal operation
Solution Approach 1:
The system applies partial action by operating the engine at or near peak efficiency torque rather than continuously at maximum torque. The pump displacement is adjusted to provide sufficient power for operational needs while keeping the engine torque load within the optimal range, avoiding excessive torque application that would reduce efficiency
Data Source
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AI summary
The application relates to control of hydrostatic pumps in a power machine (100). Signals coming form a user input device (202) are modified, depending on actual engine torque, leading to different dis¬ placement of a hydrostatic pump. The aim is to avoid excessive pow¬ er loads on the engine, which may reduce efficiency and performance and lead to engine stall.