Pump Overspeed Protection via Torque Converter Unlocking
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Solution Overview
Problem
On-highway and off-highway machines' engines and pumps are susceptible to damage from excessive speeds, which can occur due to resistive loads becoming driving loads, leading to reduced engine and component lifespan.
Innovation Solution
A pump overspeed protection system using an electronic controller to initiate a hierarchy of actions, including increasing pump displacement and switching the torque converter from a locked to an unlocked configuration, based on predefined speed thresholds to manage and reduce engine speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the machine operates with ground engaging elements creating resistive load, then the engine can drive the machine normally, but during deceleration or downgrading the resistive load becomes a driving load causing engine overspeed
Solution Approach 1:
The system applies preliminary anti-action by increasing pump displacement before the engine speed reaches dangerous overspeed levels. The electronic controller monitors engine speed and proactively increases pump displacement when speed approaches threshold values, creating a preventive counteracting load that stops overspeed conditions before they cause damage.
Solution Approach 2:
The system changes the operating parameters of the pump by varying its displacement. The electronic controller adjusts pump displacement as a controllable parameter to modulate the load on the engine, dynamically changing the system's characteristics to prevent overspeed conditions while maintaining normal operation.
2Reliability
If pump displacement is increased to reduce engine speed, then engine overspeed is prevented, but the system complexity increases with multiple speed thresholds and actions
Solution Approach 1:
The overspeed protection system is segmented into multiple discrete speed thresholds (first, second, and third thresholds) with corresponding hierarchical actions. This segmentation allows the system to apply different levels of protection measures at different severity levels, making the complex control logic more manageable and implementable through structured electronic control.
Solution Approach 2:
The system employs feedback control where the electronic controller continuously monitors engine speed and compares it against predefined thresholds. Based on the feedback from speed measurements, the controller automatically adjusts pump displacement to maintain engine speed within safe operating limits, creating a closed-loop control system.
3Reliability
If the torque converter is switched from locked to unlocked configuration to reduce engine speed, then overspeed protection is enhanced, but the control system complexity increases
Solution Approach 1:
The torque converter configuration is made dynamic rather than fixed. The electronic controller switches the torque converter between locked and unlocked configurations based on real-time engine speed conditions. This dynamic adaptation allows the system to optimize performance and provide overspeed protection by selectively changing the drivetrain's mechanical characteristics.
Data Source
AI summary
A machine having a pump overspeed protection system operating thereon includes an internal combustion engine, a plurality of ground engaging elements, and a drivetrain coupling the internal combustion engine and the ground engaging elements. The drivetrain includes a torque converter having a locked configuration and an unlocked configuration. The machine also includes a plurality of pumps driven by the internal combustion engine. An electronic control is in communication with the internal combustion engine, the torque converter, and the plurality of pumps. The electronic controller is configured to determine a pump speed of a first pump of the plurality of pumps, initiate a first action of a hierarchy of pump overspeed protection actions if the pump speed exceeds a first speed threshold, initiate a second action of the hierarchy of pump overspeed protection actions if the pump speed exceeds a second speed threshold, initiate a third action of the hierarchy of pump overspeed protection actions if the pump speed exceeds a third speed threshold, and monitor a condition of a component altered by at least one of the hierarchy of pump overspeed protection actions. At least one of the hierarchy of pump overspeed protection actions includes increasing a displacement of at least one of the plurality of pumps and at least another of the hierarchy of pump overspeed protection actions includes moving the torque converter from the locked configuration to the unlocked configuration.