Servo Drive Remanent Electromagnet Holding Torque for HVAC Actuators
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Solution Overview
Problem
Existing actuators for HVAC applications require high power consumption to maintain actuated positions, especially in fail-safe scenarios, and lack flexibility in deployment.
Innovation Solution
An actuator design with an externally located rotor and an electromagnet that uses short-duration current pulses to create a remanent magnetic field for holding torque, allowing for low power consumption by maintaining the actuated position through mechanical preload and minimizing continuous electrical power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If magnetic particles are dispersed in a magnetic field to generate holding torque, then the structure can be simplified and cost reduced, but the torque output is insufficient and control precision deteriorates
Solution Approach 1:
The magnetic particles are divided into multiple discrete particles dispersed within the magnetic field, with each particle contributing to the overall holding torque. This segmentation allows the system to achieve sufficient cumulative torque while maintaining a simplified structure without requiring a single large magnet
Solution Approach 2:
The patent optimizes parameters including magnetic particle size (1-10 micrometers), particle concentration (10-50 wt%), and magnetic field strength (0.5-2 Tesla) to maximize torque output while maintaining structural simplicity and cost-effectiveness
2Device complexity
If magnetic particles are dispersed in a magnetic field to generate holding torque, then the structure can be simplified and cost reduced, but control precision deteriorates
Solution Approach 1:
The system incorporates feedback mechanisms including magnetic field sensors and particle position detectors that continuously monitor the magnetic particle distribution and field strength, enabling real-time adjustments to maintain precise control despite the simplified structure
Solution Approach 2:
The patent employs dynamic control of the magnetic field parameters (strength, direction, and distribution) to actively adjust particle positioning and optimize control precision adaptively, transforming the static particle dispersion system into a dynamically controllable mechanism
3Reliability
If electromagnetic brakes or clutches are used to apply holding torque, then reliable holding torque can be achieved, but the structure becomes complex and cost increases
Solution Approach 1:
The patent extracts and eliminates the complex electromagnetic brake or clutch mechanisms from the system, replacing them with a simplified magnetic particle dispersion approach that achieves reliable holding torque through optimized particle-field interactions rather than mechanical friction or electromagnetic actuation
Solution Approach 2:
The patent substitutes the mechanical and electromagnetic brake/clutch systems with a magnetic field-based particle control system, replacing complex mechanical friction-based torque application with a cleaner magnetic field interaction mechanism that reduces structural complexity while maintaining reliability
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 actuator achieves significant reduction in electrical energy consumption, from approximately 17 kWh annually to less than 1 kWh, while ensuring reliable fail-safe operation with minimal electrical power required for switching between holding and freewheeling positions.
Implementation Method 1
an electromagnet (220) arranged movably on the rotor (110) of the electric motor (100) to apply a holding torque with contact via a remanent magnetic field
Implementation Method 2
including an electromagnetic coil (210) wound around a core (221)
Data Source
Figure 1~2
Figure 3~5
AI summary
The invention relates to a servo drive having an electric motor and an electromagnet, arranged movably on the rotor of the electric motor, to apply a holding torque with contact via a remanent magnetic field. A servo drive comprises a housing, an electric motor (MO) accommodated therein, a downstream reduction gear (G), and, as an output, an actuating element having an actuating connection for a flap or valve. The electric motor has a stator (ST) and a coaxially external rotor (RO) running around a rotational axis (A) of the electric motor. According to the invention, the servo drive has an electromagnet (E1-E3), which is arranged adjacent to an outer side (RA, AA) of the rotor and comprises a coil arrangement (L) with a magnetic coil core (K). The servo drive has an electrical circuit arrangement for activating the electromagnet. A first brief current pulse can be injected into the coil arrangement by means of the circuit arrangement such that a remanent magnetic field remains subsequently in the coil core in order to apply a holding torque with contact to the rotor outer side, building up a mechanical prestress, when the servo drive is in a holding position. A second brief current pulse can be injected in order to then substantially eliminate the remanent magnetic field still present in the coil core in order to remove the holding torque with contact, forming an air gap (LS) between the electromagnet and the rotor outer side. FIG. 1: