Brushless DC Motor Linear Actuator for Compact Furniture Adjustment
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Solution Overview
Problem
Existing electrically adjustable furniture, such as tables and beds, face challenges with compact design due to the large constructional height of brushed DC motors and the need for AC voltage, which is often not available or difficult to provide safely.
Innovation Solution
The use of a brushless DC motor with an integrated control device allows for a compact design and efficient operation using DC current, eliminating the need for mechanical commutation and enabling direct drive systems without gear units, with features like Hall sensors for angular position detection and pulse width modulation for smooth acceleration and regulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a brushed DC motor is used to provide sufficient mechanical energy for linear movement, then the motor can deliver adequate power, but the constructional height becomes large which impedes compact design
Solution Approach 1:
The patent replaces the mechanical commutation system (brushes and commutator) with an electronic commutation system using Hall sensors and control electronics. This substitution allows the use of a brushless DC motor which achieves the same power output with a more compact constructional height, directly resolving the contradiction between power delivery and compact dimensions
2Ease of operation
If an AC motor is used to achieve exact driving scheme, then precise control is possible, but AC voltage is usually not available in furnishing sector or requires increased safety effort
Solution Approach 1:
The patent changes the voltage parameter from AC to DC, using a brushless DC motor that operates on DC voltage commonly available in furnishing applications. The electronic commutation system with Hall sensors and controlled half-bridges provides precise control comparable to AC motors, while adapting to the DC voltage environment eliminates safety concerns and availability issues
3Device complexity
If mechanical commutation with brushes is used, then the motor structure is simpler, but the constructional height increases and efficiency decreases due to mechanical losses
Solution Approach 1:
The patent replaces mechanical commutation with electronic commutation using Hall sensors mounted on the rotor and controlled half-bridges in the stator. This eliminates brushes and commutators, reducing mechanical losses and allowing a more compact motor structure while maintaining or improving efficiency
Solution Approach 2:
The patent introduces Hall sensors as intermediaries to detect rotor position and control the commutation process electronically. These sensors replace the mechanical brush-commutator interface, enabling precise electronic control while reducing mechanical complexity and constructional height
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
This solution enables a more compact and efficient linear actuator design with reduced noise and increased efficiency, capable of providing sufficient torque at lower rotational speeds, thus enhancing the functionality and aesthetics of electrically adjustable furniture.
Implementation Method 1
a brushless DC motor (BLDC motor) arranged to effect a linear movement of the linear actuator
Implementation Method 2
which may be used by the control device for driving the motor
Data Source
AI summary
An embodiment linear actuator for an electrically adjustable piece of furniture includes a brushless DC motor arranged to effect a linear movement of the linear actuator, as well as a control device for controlling the motor.