Hybrid Work Machine Engine Power Stabilization
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Solution Overview
Problem
Conventional hybrid-type construction machinery fails to monitor the state of electrical storage devices, leading to insufficient electric power supply to the motor generator, resulting in steep fluctuations in engine power and potential engine stalling, especially when pump absorption power exceeds the engine's output upper limit.
Innovation Solution
The system computes engine target power based on load power and vehicle state, limiting hydraulic pump and motor generator power to stabilize engine power fluctuations, using a controller that manages power distribution and adjusts the rate of change to prevent steep power increases or decreases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the engine output upper limit is increased to meet high pump absorption power demands, then the power supply capability is improved, but the engine combustion efficiency decreases and exhaust gas emissions increase
Solution Approach 1:
The patent combines the engine and motor generator into a hybrid power system where the motor generator assists the engine during high load conditions. This merging allows the engine to operate at optimal combustion efficiency while the motor generator supplements power when needed, rather than relying solely on high engine output that would increase emissions.
Solution Approach 2:
The control device dynamically adjusts the engine output upper limit based on real-time conditions including pump absorption power, motor generator output capability, and electrical storage device state. By changing the engine output parameter adaptively rather than maintaining a fixed high limit, the system meets power demands while preserving combustion efficiency and reducing emissions.
2Speed
If the engine output upper limit is increased rapidly to respond to sudden pump absorption power increases, then the responsiveness is improved, but the engine power fluctuates steeply and may stall
Solution Approach 1:
The control device calculates the engine output upper limit in advance based on predicted pump absorption power and motor generator capabilities. By preparing the engine output setting before sudden load changes occur, the system can respond smoothly without steep fluctuations or stalling, maintaining both responsiveness and stability.
Solution Approach 2:
The control device continuously monitors the actual engine output, pump absorption power, and motor generator output, then adjusts the engine output upper limit accordingly. This feedback mechanism prevents steep power fluctuations by making real-time corrections, ensuring the engine operates smoothly under varying load conditions.
3Power
If the motor generator output is increased to compensate for insufficient engine power, then the power supply capability is improved, but the electrical storage device may become insufficient and engine combustion efficiency decreases
Solution Approach 1:
The control device dynamically adjusts the motor generator output based on the real-time state of the electrical storage device. When battery charge level is high, the motor generator can provide more assistance; when charge level is low, the engine output upper limit is adjusted accordingly. This dynamic adaptation optimizes power distribution while preserving electrical storage energy.
4Power
If the engine output upper limit is set high to meet maximum pump absorption power, then the power supply capability is improved, but the engine combustion efficiency decreases and exhaust gas emissions increase
Solution Approach 1:
The patent combines the engine and motor generator into a hybrid power system where the motor generator assists the engine during high load conditions. This merging allows the engine to operate at optimal combustion efficiency while the motor generator supplements power when needed, rather than relying solely on high engine output that would increase emissions.
Solution Approach 2:
The control device dynamically adjusts the engine output upper limit based on real-time conditions including pump absorption power, motor generator output capability, and electrical storage device state. By changing the engine output parameter adaptively rather than maintaining a fixed high limit, the system meets power demands while preserving combustion efficiency and reducing emissions.
Data Source
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AI summary
To provide a work machine that can suppress a steep fluctuation in engine power. The present invention includes an engine 11; a hydraulic pump 12 that is driven by the engine 11; a hydraulic actuator 17 that is driven by pressure oil discharged from the hydraulic pump 12; a motor generator 13 that drives the hydraulic pump 12; an electrical storage device 14 that transfers electric power with the motor generator 13; a load computing unit 21 that computes the load power of the engine 11; a vehicle body state management unit 22 that manages a vehicle body state including the state of the electrical storage device 14; an engine power fluctuation limitation unit 23 that computes second target power for limiting the increase rate and the decrease rate of the power of the engine 11 on the basis of the load power and the vehicle body state; a hydraulic power limitation unit 24 that limits the power of the hydraulic pump 12 on the basis of the second target power; and an assist power computation unit 25 that limits the power of the motor generator 13 on the basis of the second target power.