Double Helix Actuator with Alternating Polarity Magnets
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Solution Overview
Problem
Traditional linear actuator architectures, such as those using racetrack coils, are limited in force density at fixed power consumption and only a portion of the coil contributes to linear force, restricting their effectiveness in providing haptic sensations and torque.
Innovation Solution
A double helix actuator design featuring a coil wound around a movable proof mass within a magnetic structure, where the magnetic fields from multiple sets of alternating polarity magnets align with the coil current, enabling linear force and torque production throughout the coil, enhancing force density and motor efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If traditional racetrack coil architecture is used, then the actuator structure is simple and easy to manufacture, but the force density at fixed power consumption is limited
Solution Approach 1:
The patent transitions from a planar racetrack coil configuration to a three-dimensional double helix coil structure. The double helix configuration allows the coil to wrap around the proof mass in a spiral pattern, enabling magnetic field lines to follow the coil current throughout the entire coil structure. This dimensional change from 2D to 3D allows all portions of the coil to contribute to force production, thereby increasing force density while maintaining a compact form factor.
Solution Approach 2:
The magnetic structure is divided into multiple segments with alternating polarities arranged in a specific pattern. The cover assembly contains first and second sets of magnets with alternating polarities, while the base assembly contains a third set of magnets. This segmentation creates multiple magnetic field zones that interact with different portions of the double helix coil, ensuring that the entire coil contributes to force generation rather than just a portion of it.
2Productivity
If only a portion of the racetrack coil contributes to linear force, then the coil structure remains simple, but the motor efficiency is reduced
Solution Approach 1:
The double helix coil structure is designed so that every portion of the coil contributes to linear force production. The alternating polarity arrangement of the magnets in the cover and base assemblies creates magnetic field zones that ensure orthogonal interaction between the magnetic field and coil current throughout the entire coil length. This universal contribution of all coil portions to force generation maximizes motor efficiency and eliminates the waste present in traditional racetrack designs where only portions of the coil are effective.
Solution Approach 2:
The double helix configuration with alternating polarity magnets creates continuous useful action throughout the entire coil structure. As current flows through the helical winding, each segment of the coil experiences a magnetic field oriented to produce force in the desired direction. This continuous force generation along the entire coil path, rather than intermittent force generation in discrete sections, maintains high motor efficiency throughout the operating cycle.
3Force
If the actuator volume is increased to accommodate more coil, then the force density improves, but the device size increases
Solution Approach 1:
The double helix coil is nested around the proof mass in a compact spiral configuration, with the coil windings arranged concentrically. This nesting allows the coil to achieve greater effective length and surface area for force generation without proportionally increasing the external dimensions of the actuator. The alternating polarity magnets are arranged in corresponding nested patterns in the cover and base assemblies, maximizing the use of available space within the actuator volume.
Solution Approach 2:
By transitioning to a three-dimensional double helix configuration, the patent increases the effective coil surface area and magnetic interaction volume without proportionally increasing the external actuator dimensions. The helical winding allows the coil to utilize the vertical and radial dimensions of the proof mass, creating a more efficient use of space compared to planar racetrack configurations. This dimensional exploitation allows greater linear force generation within a compact volume.
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 double helix actuator achieves greater linear force density and motor efficiency within a fixed volume, enabling unique haptic responses and scalable designs suitable for various applications with different form factors and power constraints.
Implementation Method 1
the magnetic field generated by the entirety of the double helix coil contributes to a linear force direction of the actuator
Implementation Method 2
the magnetic fields provided by the first, second and third sets of magnets follow a direction of the coil current
Data Source
AI summary
A double helix actuator is disclosed that includes a double helix coil wound around a movable proof mass that is enclosed within a magnetic structure. The double helix coil and the magnetic structure are arranged relative to each other so that the magnetic field generated by the entirety of the double helix coil contributes to a linear force direction of the actuator. The double helix actuator produces a greater linear force density compared to traditional racetrack coil actuators, where only a portion of the coil contributes to the linear force. The double helix actuator also produces torque in addition to linear force which allows the double helix to provide unique haptic sensations in a variety of applications.