Hybrid Working Machine Control for Variable Engine Assist
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Solution Overview
Problem
Existing working machines, such as compact track loaders, struggle to flexibly adjust output and provide adequate assistance based on varying work forces and engine power requirements, leading to insufficient performance in different work modes.
Innovation Solution
A working machine equipped with a motor/generator that functions as both a motor to assist the engine and a generator to generate electricity, along with a control system that adjusts rotation speeds based on operation amounts and engine speed changes, allowing flexible output adjustment and effective assistance when needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the assisting action is determined according to work mode (excavation vs. non-excavation), then the control system is simple, but the assisting action cannot sufficiently correspond to the actual work force requirements
Solution Approach 1:
The patent changes the switching rotation speeds dynamically based on the operation amount of the work operation member. When the operation amount is large (indicating high work force demand), the switching rotation speed is increased to allow the engine to maintain higher speeds before switching to motor assistance. This dynamic adjustment ensures the assisting action adequately matches the actual work requirements while keeping the control system relatively simple.
2Device complexity
If the switching rotation speed is fixed, then the control is simple, but the output cannot be flexibly adjusted depending on the work
Solution Approach 1:
The switching rotation speed is made variable based on the operation amount detected by the operation detecting device. When the work operation member is operated with large amplitude (high output demand), the switching rotation speed is set higher, allowing the engine to operate at higher speeds before motor assistance engages. This provides flexible output adjustment matched to actual work conditions.
Solution Approach 2:
The control system continuously detects the operation amount of the work operation member and uses this feedback to adjust the switching rotation speed accordingly. This closed-loop control enables the system to adapt its behavior (switching point between engine-only and hybrid mode) based on real-time operator input and work demands.
3Power
If the motor/generator assists the engine at low rotation speeds, then the engine power is supplemented, but the assisting action may be performed unnecessarily when the engine does not need assistance
Solution Approach 1:
The switching rotation speed threshold is dynamically adjusted based on operation amount. When operation amount is small (low work demand), the switching rotation speed is set lower, preventing unnecessary motor assistance when the engine can handle the load alone. This reduces energy consumption by avoiding unnecessary motor/generator engagement while still providing power supplementation when genuinely needed.
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 flexible output adjustment and effective assistance, ensuring optimal performance across varying work conditions.
Implementation Method 1
a motor/generator (63) to perform an assisting action in which the motor/generator (63) functions as a motor to assist the engine (60) in driving
Implementation Method 2
an electricity generating action in which the motor/generator (63) functions as a generator to generate electricity using power from the engine (60)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
It is possible to flexibly change output depending on work. A working machine (1) comprises: a machine body (2); an engine (60) provided on the machine body (2): a motor/generator to perform an assisting action in which the motor/generator functions as a motor to assist the engine in driving and an electricity generating action in which the motor/generator functions as a generator (63) to generate electricity using power from the engine (60); a working device (3) configured to function using power from the engine (60) and the motor/generator; a work operation member (37) for operation of the working device (3); an action control unit (70d) to cause the assisting action to be performed when a rotation speed of the engine (60) is equal to or less than a first rotation speed and cause the electricity generating action to be performed when the rotation speed of the engine is equal to or greater than a second rotation speed, the second rotation speed being greater than the first rotation speed; and a switching changing unit to change the first rotation speed or the second rotation speed according to an operation amount of the work operation member (37).