Hydrostatic Prime Mover Speed Control for Engine Stall Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing working machines, such as skid-steer loaders and compact track loaders, face challenges in preventing engine stalls while maintaining operability, as existing anti-stall control systems are inadequate in managing engine speed and hydraulic pressure effectively.
Innovation Solution
A working machine equipped with a rotation-speed operation actuator, a rotation detector, a hydraulic pump, an operation valve, and a controller that adjusts the primary pressure based on the difference between target and actual rotation speeds, and secondary pressure thresholds to optimize hydraulic unit performance and prevent engine stalls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pressure control valve is controlled to rapidly reduce the traveling primary pressure to suppress engine stall, then engine stall is prevented, but the traveling secondary pressure may become insufficient to ensure desired operability
Solution Approach 1:
The patent applies dynamics by making the pressure control characteristic changeable based on operating conditions. The controller switches between a first pressure control characteristic (for rapid pressure reduction to prevent engine stall) and a second pressure control characteristic (for maintaining sufficient secondary pressure for operability). This dynamic adjustment resolves the contradiction by adapting the pressure control behavior to the current operational state, ensuring both engine protection and hydraulic unit functionality.
Solution Approach 2:
The patent changes the pressure control parameters (control characteristics) based on the operational mode. When the hydraulic unit requires high operability, the controller selects the second pressure control characteristic that maintains higher secondary pressure. When engine stall risk is detected, it switches to the first characteristic that rapidly reduces primary pressure. This parameter change approach allows the system to optimize between preventing engine stall and ensuring hydraulic operability.
2Ease of operation
If the traveling primary pressure is maintained high to ensure hydraulic unit operability, then desired operability is achieved, but engine stall risk increases under high load conditions
Solution Approach 1:
The system dynamically adjusts the pressure control characteristic based on real-time monitoring of engine load and hydraulic pressure conditions. When the engine is under high load, the controller switches to the first pressure control characteristic that rapidly reduces primary pressure to prevent stall. When load is acceptable, it uses the second characteristic that maintains higher pressure for operability. This dynamic response resolves the contradiction between maintaining operability and preventing engine stall.
Solution Approach 2:
The controller continuously monitors engine load conditions and hydraulic pressure levels, using this feedback to determine which pressure control characteristic to apply. The feedback mechanism allows the system to detect when high primary pressure is causing engine stress and switch to the protective characteristic, while also detecting when sufficient pressure is being maintained for proper hydraulic unit operation. This closed-loop feedback resolves the contradiction by continuously optimizing the pressure control strategy.
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
The solution effectively suppresses engine stalls and ensures operability by dynamically adjusting hydraulic pressures, enhancing the machine's responsiveness and efficiency in various operational conditions.
Implementation Method 1
a hydraulic pump driven by power from the prime mover to deliver a hydraulic fluid, a hydraulic unit to actuate in accordance with a hydraulic fluid
Implementation Method 2
an actuation valve operable in accordance with a control signal to change a primary pressure defining the pilot pressure of the pilot fluid supplied from the hydraulic pump to the operation valve
Implementation Method 3
an operation valve operable to change a pilot pressure of a pilot fluid defining the hydraulic fluid supplied from the hydraulic pump to the hydraulic unit in accordance with an operation of an operation member
Data Source
AI summary
A working machine includes a prime mover, a rotation-speed operation actuator, a rotation detector, a hydraulic pump, a hydraulic unit, an operation valve capable of changing a pilot pressure of a pilot fluid supplied from the hydraulic pump to the hydraulic unit in accordance with an operation of an operation member, an actuation valve operating in accordance with a control signal and capable of changing a primary pressure as the pilot pressure of the pilot fluid supplied from the hydraulic pump to the operation valve, and a controller that outputs the control signal based on a difference between target and actual rotation speeds to the actuation valve to control an opening thereof. The controller has a mode including calculating the control signal based on the difference, correcting the calculated control signal, and increasing or decreasing a target primary pressure value set in accordance with the control signal.