Hybrid Construction Machine Power Distribution Control
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Solution Overview
Problem
Hybrid construction machines face challenges in maintaining operability during combined operations like swing boom raising, where the balance between swing speed and boom raising speed is disrupted due to variations in power distribution between the engine and electric storage devices, leading to potential fuel inefficiency and inadequate power supply.
Innovation Solution
A hybrid construction machine with a swing structure, work machine, engine, first electric motor, hydraulic pump, and second electric motor, utilizing a control unit that distributes power from electric storage devices based on output level and stored energy to maintain balance between swing speed and boom raising speed, and an engine revolution speed control unit to adjust engine speed according to power demand.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If power is distributed from the engine and electric storage device to drive both the hydraulic pump and swing electric motor during combined operations, then the maximum system power is sufficient to perform both operations, but the balance between swing speed and boom raising speed becomes difficult to control
Solution Approach 1:
The power distribution is segmented into two independent control paths: one path controls the hydraulic pump (driving boom, arm, bucket) with a dedicated hydraulic control unit, and the other path controls the swing electric motor (driving swing structure) with a dedicated swing control unit. This segmentation allows each operation to be controlled independently without interfering with the other, resolving the balance control issue while maintaining maximum system power capability.
Solution Approach 2:
The system dynamically adjusts power distribution between the engine and electric storage device based on real-time operational demands. The control units monitor the state of charge of the electric storage device and automatically switch between engine-driven power and electrically-driven power for the swing motor, enabling flexible and adaptive power management that maintains operability balance during combined operations.
2Power
If the generator motor is supplied with electric power from the electric storage device to assist the engine, then the power supply for both operations is ensured, but the fuel economy deteriorates
Solution Approach 1:
The electric storage device serves itself by automatically managing its own charge and discharge cycles. During swing operations, the swing electric motor can draw power from the electric storage device without requiring continuous engine assistance, allowing the engine to operate more efficiently and improve overall fuel economy while ensuring adequate power supply for combined operations.
Solution Approach 2:
The system changes the power source parameter dynamically based on operational conditions. When the electric storage device has sufficient charge, it switches to electric power for the swing motor; when charge is low, it switches to engine power. This parameter change optimizes fuel economy by using electric power during high-demand swing operations while maintaining power supply adequacy.
3Use of energy by moving object
If the capacitor quickly collects power regenerated from swing braking, then the energy efficiency is improved, but the power necessary for driving the hydraulic pump may not be provided when needed
Solution Approach 1:
The electric storage device serves multiple functions: it stores regenerated power from swing braking, provides power to the swing electric motor during swing operations, and can also support the hydraulic pump during high-demand operations. This multi-functionality ensures that energy efficiency is improved through regenerative braking while power availability is maintained through the device's ability to supply power to multiple systems.
Solution Approach 2:
The electric storage device acts as an intermediary between the regenerative braking system and the power-consuming systems (swing motor and hydraulic pump). It buffers the intermittent regenerated power and releases it when needed, ensuring both energy efficiency through recovery and adequate power availability when demands arise during combined operations.
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
Ensures a good balance between swing speed and boom raising speed, maintaining operability and fuel efficiency by effectively distributing power from the engine and electric storage devices, and adjusting engine speed to meet power demands during combined operations.
Implementation Method 1
an engine-driven generator motor capable of generating electric power
Implementation Method 2
an electric storage device such as a capacitor and battery
Implementation Method 3
the engine driving a hydraulic pump that delivers pressure to rotate a hydraulic motor
Data Source
AI summary
Provided is a hybrid construction machine together with a method for controlling that construction machine in a manner ensuring the operability of its combined operations regardless of fluctuations in the load on its work machine.The hybrid construction machine has: a swing structure; a work machine attached to the swing structure; an engine mounted on the swing structure; a first electric motor driven by the engine, the motor being capable of generating power; a hydraulic pump driven by the engine and the first electric motor; a second electric motor for driving the swing structure; and a plurality of electric storage devices, wherein the hybrid construction machine further includes a first control unit which, in a combined operation involving the work machine and the swing structure, drives and controls the second electric motor by use of the electric power supplied from at least one electric storage device selected from the storage devices and from another electric storage device offering a higher output level and a lower stored energy level per unit weight than the selected at least one electric storage device, and drives and controls the hydraulic pump by use of the engine.