Hybrid Construction Machine Swing Mode Control
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Solution Overview
Problem
Hybrid construction machines employing both hydraulic and electric motors for swing structures face issues such as hunting, operational strangeness, overheating, and increased size or cost due to the use of electric motors, and are prone to low energy states or overcharged states of the electricity storage device, leading to insufficient torque generation and safety concerns during high-speed operations.
Innovation Solution
A hybrid construction machine with a swing-mode switching system that allows manual operation between hydraulic/electric combined swing mode and hydraulic solo swing mode, using a control device to switch between the two modes based on a manually operated selector switch or display device, ensuring continuous operation without electric motor torque failure due to energy state issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an electric motor is used to drive the swing structure, then energy regeneration during braking is possible, but hunting occurs in low speed range and stopped state
Solution Approach 1:
The patent combines a hydraulic motor and an electric motor to form a hybrid drive system for the swing structure. The hydraulic motor provides stable low-speed operation and braking control, while the electric motor handles high-speed operations and enables energy regeneration during deceleration. This merging resolves the contradiction by allowing the system to leverage the strengths of both motor types without suffering from the electric motor's hunting problem alone.
Solution Approach 2:
The control device acts as an intermediary that intelligently switches between hydraulic-only mode, electric-only mode, and hybrid mode based on operating conditions. During low-speed operations or stopped states, it uses the hydraulic motor to avoid hunting, while during high-speed operations with deceleration, it engages the electric motor for energy regeneration, thus resolving the contradiction between energy recovery and operational stability.
2Loss of energy
If an electric motor is used to drive the swing structure, then energy efficiency is improved, but operational strangeness occurs due to different characteristics from hydraulic motors
Solution Approach 1:
The system dynamically switches between different operational modes (hydraulic-only, electric-only, hybrid) based on real-time operating conditions such as swing speed, load, and energy state of the electricity storage device. This dynamic adaptation allows the system to maintain familiar hydraulic-like characteristics during low-speed operations while enabling energy-efficient electric operation during high-speed operations, thus resolving the contradiction between energy efficiency and operational familiarity.
3Loss of energy
If an electric motor is used to drive the swing structure, then kinetic energy regeneration is possible, but overheating of motor or inverter occurs during continuous torque output with no rotation
Solution Approach 1:
The control device serves as an intermediary that monitors the thermal state of the electric motor and inverter, and switches between hydraulic and electric drive modes accordingly. During continuous torque output operations (pressing operations), it engages the hydraulic motor which does not suffer from overheating, thereby preventing thermal damage while maintaining the ability to use electric motor for kinetic energy regeneration during appropriate operations.
4Power
If an electric motor with high output equivalent to hydraulic motor is used, then sufficient torque is available, but overall size and cost increase considerably
Solution Approach 1:
Instead of using a single oversized electric motor to cover all operating conditions, the system uses a smaller electric motor that operates only when needed (during high-speed operations with deceleration), while relying on the hydraulic motor for other operations. This partial action approach reduces the size and cost of the electric motor while still achieving the desired torque output when electric operation is beneficial.
Solution Approach 2:
The hybrid system merges a smaller electric motor with a hydraulic motor to achieve the combined torque output of what would otherwise require a much larger electric motor alone. This merging allows the system to share the torque burden between the two motors, reducing the size and cost of individual components while maintaining sufficient total torque output.
5Loss of energy
If the electric motor is constantly in charge of certain part of total torque, then energy saving is achieved, but torque becomes insufficient when electricity storage device is in low energy state or overcharged state
Solution Approach 1:
The control device continuously monitors the energy state of the electricity storage device and adjusts the operational mode accordingly. When the electricity storage device is in a normal state, it uses the electric motor for energy-saving operation. When the device is in low energy state or overcharged state, it switches to hydraulic-only operation to ensure sufficient torque availability, thus resolving the contradiction between energy saving and torque reliability through feedback-based adaptive control.
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 safe and efficient operation by preventing electric motor torque failure from low energy or overcharged states, maintaining energy savings in normal operation, and providing a familiar operational feel similar to conventional hydraulic machines.
Implementation Method 1
the electric motor regenerates the kinetic energy of the swing structure into electric energy and accumulates the regenerated energy in a battery
Implementation Method 2
hydraulic pressure generated by a hydraulic pump which is driven by the engine
Data Source
AI summary
A hybrid construction machine has an electric motor for driving the swing structure, and the electric motor is prevented from becoming incapable of generating torque due to a low energy state or an overcharged state of an electricity storage device. A swing-mode selector switch 77 which is manually operated switches between a hydraulic/electric combined swing mode for driving the swing structure by driving both the electric motor and a hydraulic motor and a hydraulic solo swing mode for driving the swing structure by driving only the hydraulic motor. For a normal operation, the swing mode is initially set in the hydraulic/electric combined swing mode. For a specific operation, the operator switches the swing-mode selector switch from a hydraulic/electric combined swing position to a hydraulic solo swing position.