Hydraulic Steering Pump Power Reversal During Engine Failure
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Solution Overview
Problem
Hydraulic steering systems in large machines fail to maintain steering during a loss of primary power, as they rely on engine-driven pumps, and secondary pumps are costly and prone to wear when frequently activated.
Innovation Solution
A method and system that utilize a controller to detect engine speed reduction, reduce transmission power, and command a power reversal through the transmission to maintain engine speed and hydraulic steering pump operation, eliminating the need for a secondary pump by leveraging machine momentum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a secondary steering pump is used to backup the primary pump during engine failure, then steering reliability is improved, but system complexity and cost increase
Solution Approach 1:
The system uses the machine's own momentum and kinetic energy to drive the steering pump during engine failure, eliminating the need for a separate secondary pump. The transmission system reverses power flow to maintain engine RPM and hydraulic pressure using only the primary pump and existing mechanical components.
Solution Approach 2:
The transmission system performs multiple functions: it serves as both the power transmission mechanism for machine operation and as a backup power source for the steering system during engine failure. The same transmission components are used to both drive the machine and maintain steering capability.
2Reliability
If a secondary steering pump is installed, then steering availability during engine failure is improved, but manufacturing cost increases
Solution Approach 1:
The system utilizes the machine's existing kinetic energy and mechanical components to provide backup steering power. The primary pump, transmission, and engine together form a self-sufficient backup system that requires no additional expensive components.
Solution Approach 2:
The solution extracts and utilizes the existing mechanical energy in the system (machine momentum) to power the steering pump, rather than adding a separate power source. This removes the need for expensive secondary pump installations.
3Reliability
If the engine speed drops during failure, then the primary steering pump cannot maintain operation, but adding a secondary pump increases wear and maintenance requirements
Solution Approach 1:
The system maintains the primary pump's operation by using machine momentum to drive the transmission in reverse, which keeps the engine running at sufficient RPM. This prevents the need to activate a secondary pump, thereby extending the service life of the primary pump and reducing maintenance requirements.
Solution Approach 2:
The control system continuously monitors engine RPM and transmission state, dynamically adjusting the power flow to maintain engine speed above the threshold required for primary pump operation. This feedback control ensures the primary pump remains operational without requiring secondary backup activation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables continuous steering during engine power loss without a secondary pump, reducing wear on primary systems and providing a backup power source for machines without secondary pumps, ensuring effective steering until the machine comes to a stop.
Implementation Method 1
commanding a power reversal through the transmission to cause machine momentum to drive the engine
Data Source
AI summary
A system and method are provided for maintaining hydraulic steering for a machine during engine out or engine lugging conditions. The machine includes a torque-controlled transmission driven by an engine, the engine further being linked to a hydraulic steering pump that provides hydraulic power to a steering actuator. The machine may be, for example, a wheel loader or an off highway truck. The system and method include detecting an undesirable reduction of engine speed while the machine is travelling, and responsively reducing the transmission power to maintain the engine speed at a desired level to power the hydraulic steering pump. When the reduced requested transmission power reaches zero, a power reversal through the transmission is commanded to maintain the engine speed at the desired level to power the hydraulic steering pump.