Working Machine Engine Stall Prevention via Dynamic Hydraulic Flow Control
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Solution Overview
Problem
Working machines such as skid-steer loaders and compact track loaders experience unintended engine stalls due to high loads, which existing technologies fail to adequately address.
Innovation Solution
A working machine equipped with a controller that adjusts hydraulic fluid flow rates to actuators based on actual prime mover rotation speed, using solenoid valves to limit fluid flow when a predetermined drop in speed is detected, thereby preventing engine stalls during high-load operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If hydraulic pump power is increased to provide high flow rate to actuators for high-power work, then work capability is improved, but prime mover rotation speed drops causing unintended engine stalls
Solution Approach 1:
The patent implements dynamic control of hydraulic pump power by adjusting the solenoid valve duty cycle based on real-time monitoring of prime mover rotation speed and detected load conditions. This allows the system to optimize the balance between hydraulic pump power and prime mover stability dynamically, preventing engine stalls while maintaining high work capability when needed.
2Reliability
If solenoid valve duty cycle is increased to limit hydraulic fluid flow and prevent engine stalls, then prime mover stability is improved, but actuator power and work capability are reduced
Solution Approach 1:
The patent changes the parameter of solenoid valve duty cycle dynamically based on detected load conditions and prime mover rotation speed. By adjusting this parameter in response to actual operating conditions, the system maintains actuator power when the prime mover is stable while limiting power only when necessary to prevent stalls, thus resolving the contradiction between stability and power.
3Reliability
If existing load prevention techniques are used, then light-load engine stalls are prevented, but high-load operation scenarios are not addressed and engine stalls still occur
Solution Approach 1:
The patent implements a feedback mechanism that continuously monitors prime mover rotation speed and detected load conditions to determine appropriate solenoid valve duty cycles. This feedback-based approach enables the system to adapt to various load conditions including high-load scenarios that existing techniques do not address, improving both reliability and adaptability across the full range of operating conditions.
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
Effectively prevents engine stalls by dynamically managing hydraulic fluid flow, ensuring consistent operation even under high-load conditions.
Implementation Method 1
a solenoid valve to change a flow rate of the hydraulic fluid to the at least one actuator based on a control signal inputted thereto
Implementation Method 2
a rotation speed sensor to detect an actual rotation speed of the prime mover
Data Source
AI summary
A working machine includes a pump actuated by power from a prime mover to deliver hydraulic fluid, a working unit including a working device and an attachment to perform work upon actuation, by hydraulic fluid, of actuator(s) included in the working device and/or the attachment, a solenoid valve to change a flow rate of hydraulic fluid to the actuator(s) based on a control signal, a controller to input the control signal into the valve, an accelerator to input a target rotation speed of the prime mover, and a rotation speed sensor to detect an actual rotation speed of the prime mover. The controller is configured or programmed to, during high-load work, if a decrease in actual rotation speed relative to the target rotation speed reaches a threshold or greater, change the control signal based on the actual rotation speed to limit the flow rate of hydraulic fluid to the actuator(s).