Forklift Inductive Charging Coil Alignment for Stray Field Reduction
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Solution Overview
Problem
Industrial trucks with inductive charging devices face inefficiencies due to translational and rotational deviations between the secondary coil plate and the primary coil plate, leading to stray fields and reduced power transmission, which can be exacerbated by loading conditions and tire wear, resulting in suboptimal charging efficiency and potential safety issues when operating near people.
Innovation Solution
A movable secondary coil plate with an alignment mechanism that compensates for translational and rotational deviations in all six degrees of freedom, using actuators and fitting devices to achieve optimal geometric configuration and minimize stray fields, allowing for high-efficiency inductive power transmission and operation at a constant resonance point.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the secondary coil plate is arranged on the underside of the truck and the primary coil plate is arranged on or in the track, then the inductive charging device enables contactless charging of the traction battery, but translational and rotational deviations between the coil plates occur due to positioning inaccuracies, loading conditions, and tire wear, leading to stray fields and reduced power transmission efficiency
Solution Approach 1:
The patent applies the dynamics principle by making the secondary coil plate movable relative to the truck body through an alignment mechanism. This mechanism includes actuators that can actively adjust the position and orientation of the secondary coil plate in real-time to compensate for deviations caused by positioning inaccuracies, loading conditions, and tire wear. The system transitions from a static coil arrangement to a dynamic one that can adapt to changing conditions, thereby maintaining optimal alignment between the primary and secondary coil plates and preventing stray fields that would reduce power transmission efficiency
Solution Approach 2:
The patent implements feedback by incorporating sensors that continuously monitor the relative position and orientation between the primary and secondary coil plates. This feedback information is fed to a control system that activates the alignment mechanism to correct any detected deviations. The feedback loop ensures that the secondary coil plate maintains optimal alignment with the primary coil plate despite external disturbances, thereby maximizing power transmission efficiency and preventing energy loss through stray fields
2Device complexity
If the secondary coil plate is fixed on the truck, then the device structure is simple, but deviations in all six degrees of freedom occur under varying operating conditions, resulting in stray fields and reduced coupling area for power transmission
Solution Approach 1:
The patent applies the dynamics principle by making the secondary coil plate movable relative to the truck body through an alignment mechanism. This mechanism includes actuators that can actively adjust the position and orientation of the secondary coil plate in real-time to compensate for deviations caused by positioning inaccuracies, loading conditions, and tire wear. The system transitions from a static coil arrangement to a dynamic one that can adapt to changing conditions, thereby maintaining optimal alignment between the primary and secondary coil plates and preventing stray fields that would reduce power transmission efficiency
Solution Approach 2:
The patent applies parameter changes by enabling the secondary coil plate to adjust its spatial parameters (position and orientation) in response to varying operating conditions. The alignment mechanism modifies the geometric parameters of the coil plate arrangement, such as its distance from the truck body and its angular orientation, to maintain optimal alignment with the primary coil plate. This dynamic parameter adjustment prevents the formation of stray fields and maintains efficient power transmission despite changes in loading conditions or tire wear
3Loss of energy
If the primary coil plate is raised to minimize the vertical air gap, then the magnetic coupling between coil plates is optimized, but the alignment mechanism becomes more complex and the risk of collision between coil plates increases
Solution Approach 1:
The patent applies the dynamics principle by making the secondary coil plate movable relative to the truck body through an alignment mechanism. This mechanism includes actuators that can actively adjust the position and orientation of the secondary coil plate in real-time to compensate for deviations caused by positioning inaccuracies, loading conditions, and tire wear. The system transitions from a static coil arrangement to a dynamic one that can adapt to changing conditions, thereby maintaining optimal alignment between the primary and secondary coil plates and preventing stray fields that would reduce power transmission efficiency
Solution Approach 2:
The patent applies beforehand cushioning by designing the alignment mechanism with collision prevention capabilities. The system includes sensors and control logic that detect when the secondary coil plate is approaching the primary coil plate too closely, and automatically adjust the position to prevent collision. This proactive measure allows the system to minimize the vertical air gap for optimal magnetic coupling while maintaining a safety margin that prevents damage from accidental contact between the coil plates
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 alignment mechanism ensures optimal alignment and minimal distance between the coil plates, enhancing inductive power transmission efficiency, allowing for high nominal power operation while minimizing stray fields and maintaining efficient charging even under varying conditions.
Implementation Method 1
An inductive charging device uses at least one pair of coils through which a common flux of an alternating magnetic field flows
Implementation Method 2
the secondary coil plate has a vertical air gap from the primary coil plate. To minimize this vertical air gap and optimize the magnetic coupling of the secondary coil plate with the primary coil plate
Data Source
Figure 1~2
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Figure 5~6
AI summary
The invention relates to a forklift truck (1) with a battery-electric drive system comprising a traction battery and with a secondary coil plate (2) of an inductive charging device (3) for charging the traction battery of the forklift truck (1). The secondary coil plate (2) is movably arranged on the forklift truck (1) by means of an alignment mechanism (10). The alignment mechanism (10) enables the secondary coil plate (2) to be aligned with a primary coil plate (7) of the inductive charging device (3) in at least one translational axis (x; y; z) and/or about at least one rotational axis (α; β; γ).