Hybrid Work Machine Forced Battery Charging Control
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Solution Overview
Problem
Hybrid work machines face challenges in fuel consumption and noise reduction due to limitations in engine output power torque and battery charging efficiency, leading to reduced usability and inappropriate battery charging.
Innovation Solution
A hybrid work machine with a governor device controlling engine speed and fuel injection, coupled with a generator motor and controller sections for output power assist and forced charging, ensuring safe and reliable battery charging by adjusting engine speed and torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If torque reduction control is exercised to reduce maximum absorption torque of the hydraulic pump, then the engine can generate extra torque for battery charging, but the output power torque of the hydraulic pump is limited and machine performance is reduced
Solution Approach 1:
The system dynamically switches between normal operation mode and forced charging mode based on battery charge level. In forced charging mode, the gate lock lever disables hydraulic actuators and the controller increases engine speed to dedicated charging RPM, allowing full engine power to be directed to the generator for battery charging without limiting hydraulic pump torque during normal operation
Solution Approach 2:
The system performs periodic monitoring of battery charge amount and alternates between work mode and charging mode. When battery charge falls below threshold, the system transitions to forced charging mode; when charge is sufficient, it returns to normal work mode, creating a periodic cycle that ensures battery maintenance without continuous performance degradation
2Use of energy by moving object
If the engine speed is increased to an appropriate charging speed for forced charging, then the battery can be charged more effectively, but the machine cannot perform work simultaneously
Solution Approach 1:
The system extracts the charging function from the normal work operation by disabling the hydraulic actuators through the gate lock lever. This separation allows the engine to be dedicated entirely to charging operations without compromising work capability, as the work system is properly disabled and can be reactivated when charging is complete
3Loss of energy
If the engine is miniaturized to achieve fuel savings and noise reduction, then the engine output power torque is limited, but the hybrid system requires sufficient torque for both hydraulic pump and generator
Solution Approach 1:
The system performs preliminary action by increasing engine speed to optimal charging RPM before engaging forced charging mode. This ensures the engine operates at its most efficient point for power generation, maximizing torque output to the generator while maintaining fuel efficiency, and prepares the hybrid system to handle the power demands of both pump and generator
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
Achieves fuel savings, noise reduction, and reliable battery charging by optimizing engine output and torque management, enhancing machine performance and usability.
Implementation Method 1
a generator motor coupled to the engine; an electric storage device that supplies and receives electric power to and from the generator motor
Implementation Method 2
a governor device that controls a fuel injection amount of the engine in such a manner that an engine speed of the engine is changed in response to the target engine speed of the engine and an output power torque of the engine increases as a load torque of the engine increases
Data Source
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AI summary
To achieve saving of fuel consumption and noise reduction by adopting a hybrid type and miniaturizing an engine and to ensure safe and reliable battery charging in a case in which a charge amount of a battery is quite insufficient, a hydraulic work machine includes: a gate lock sensor (28); a forced charging switch (41); a work machine monitor (43) that notifies an operator that a charging rate of a battery (33) falls to be lower than a critical charging rate; and a machine controller (46). The machine controller (46) actuates a generator motor (31) as a generator to forcedly charge the battery (33) when a gate lock lever (26) is operated to a lock position (D), an engine control dial (12) designates a low idle engine speed, and the forced charging switch (41) is operated.