Hybrid Swing Drive Torque Control for Fuel Efficiency
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Solution Overview
Problem
Hydraulic swing motor efficiency deteriorates at small operating strokes or low swing speeds in hybrid construction machines, leading to increased fuel consumption and energy loss, as the hydraulic fluid flow rate decreases and resistance increases, limiting the hydraulic fluid's flow into the motor.
Innovation Solution
A work machine with a hybrid system that includes a controller to optimize torque distribution between the electric and hydraulic swing motors, using a control block diagram to compute and adjust torque commands based on swing operating stroke and speed, prioritizing the electric motor at small strokes and low speeds to reduce fuel consumption by minimizing hydraulic motor inefficiencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the hydraulic swing motor is used to drive the swing structure at small operating strokes or low speeds, then the hydraulic fluid flow rate decreases and resistance increases, but the motor efficiency deteriorates and fuel consumption increases
Solution Approach 1:
The control device changes the operating parameters of the hydraulic swing motor by adjusting the hydraulic fluid flow rate based on the operating stroke and swing speed. When the operating stroke is small or swing speed is low, the control device reduces the hydraulic fluid flow rate to the hydraulic swing motor, thereby improving hydraulic motor efficiency and reducing fuel consumption while maintaining the required swing performance.
Solution Approach 2:
The system dynamically adjusts the hydraulic fluid flow distribution between the hydraulic swing motor and other hydraulic actuators based on real-time operating conditions (swing stroke and swing speed). This dynamic control ensures that the hydraulic swing motor operates in its efficient range even during small strokes or low-speed operations, preventing efficiency deterioration and reducing overall fuel consumption.
2Use of energy by moving object
If the hydraulic fluid flow rate to the hydraulic swing motor is reduced at small operating strokes, then fuel consumption decreases, but the swing speed and response may be affected
Solution Approach 1:
The control device uses feedback from sensors monitoring the swing stroke and swing speed to dynamically adjust the hydraulic fluid flow rate to the hydraulic swing motor. This closed-loop control ensures that the swing speed and response are maintained within acceptable ranges while optimizing fuel consumption by reducing hydraulic fluid flow only when operating conditions indicate low efficiency.
Solution Approach 2:
The control device changes the hydraulic fluid flow rate parameter based on the relationship between operating stroke and swing speed. By establishing optimal flow rate parameters for different operating conditions, the system maintains adequate swing speed and response while minimizing fuel consumption during small strokes or low-speed 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
The system effectively reduces fuel consumption by ensuring the swing structure is driven primarily by the electric motor during low-efficiency hydraulic motor conditions, enhancing overall efficiency and reducing energy loss, while allowing for dimensional and cost reductions in motor design.
Implementation Method 1
an electric swing motor 25...a torque of the electric swing motor 25
Implementation Method 2
a hydraulic swing motor 27...a torque of the hydraulic swing motor 27...a flow of a hydraulic fluid from a hydraulic pump
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
Provided is a work machine using a hydraulic motor and an electric motor to drive a swing structure, the work machine being adapted to reduce fuel consumption in regions where swinging by the hydraulic motor is prone to deteriorate in efficiency, such as when an operating stroke of swinging is small. The work machine includes an engine, a hydraulic pump driven by the engine, a swing structure, an electric motor for driving the swing structure, a hydraulic motor for driving the swing structure, the hydraulic motor being driven by the hydraulic pump, and a swing control lever device that commands the swing structure to be driven. The work machine further includes a control device operates in either an electric swing mode in which the swing structure is driven mainly by torque of the electric motor or a hydraulic swing mode in which the swing structure is driven mainly by torque of the hydraulic motor, depending on an operating stroke of the control lever device and/or a swing speed of the swing structure.