Actuator with Switchable Releasing Speed via Brush Control
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Solution Overview
Problem
Conventional actuators used in applications like electric hospital beds face challenges with slow operation and difficulty in quickly adjusting to emergency situations due to large forces and the need for manual operation, which can be inconvenient and laborious, and the introduction of high-speed releasing mechanisms increases the actuator's volume and affects installation.
Innovation Solution
An actuator with switchable releasing speed is designed, featuring a motor with a stator, rotor, commutators, and brushes that allow for adjustable rotational speed by varying the connection of brushes to DC voltage, enabling multiple speed settings through a multistage switch, and includes a worm wheel and worm gear for axial movement, allowing for convenient operation and high-speed release without the need for additional high-speed releasing mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a high-speed releasing mechanism is introduced to enable quick restoration in emergency situations, then the releasing speed is improved, but the volume of the actuator increases and affects installation
Solution Approach 1:
The patent applies dynamics by making the screw mechanism capable of operating in two distinct modes: self-locking mode for normal operation and non-self-locking mode for emergency release. The screw transitions between these states based on the positioning of the inclined surface relative to the elastic component, enabling speed adjustment without adding separate mechanisms. This dynamic reconfiguration allows the same mechanical structure to provide both slow controlled movement and fast emergency release.
Solution Approach 2:
The patent changes the friction parameter of the screw mechanism by altering its engagement state. In normal operation, the screw maintains high friction through self-locking engagement. In emergency mode, the inclined surface repositions the elastic component to reduce friction engagement, enabling non-self-locking operation and rapid release. This parameter change (friction coefficient) allows the system to switch between slow and fast modes using the existing screw structure.
2Measurement precision
If a lock mechanism is provided to lock the actuation rod when the motor drives the screw rotating, then the positioning accuracy is improved, but the operation becomes inconvenient and laborious
Solution Approach 1:
The patent applies self-service by designing the screw mechanism to automatically lock and unlock based on its own operational state. During normal operation, the screw's thread geometry and elastic component automatically maintain the locked position without external intervention. When emergency release is needed, the system automatically transitions to non-self-locking mode through the inclined surface mechanism, eliminating the need for manual operation of separate lock/release mechanisms.
Solution Approach 2:
The patent replaces complex mechanical lock/release mechanisms with a simplified screw-based system that uses friction and elastic deformation to achieve locking. Instead of traditional brakes, clamps, or latches, the invention uses the screw's own thread engagement and an elastic component pressed against the screw body to provide automatic locking during normal operation and automatic release during emergency conditions.
3Force
If the actuator operates with large forces to drive the bed shelf, then the lifting capability is improved, but the operation becomes slow and affects emergency response time
Solution Approach 1:
The patent applies dynamics by enabling the screw mechanism to switch between self-locking and non-self-locking states. During normal operation, the self-locking state provides high friction for controlled, forceful lifting. During emergency release, the non-self-locking state reduces friction resistance, allowing rapid movement under the same force output from the actuation rod. This dynamic state change allows the system to maintain lifting capability while enabling fast response when needed.
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 provides flexible speed adjustment, enabling quick operation in emergency situations while minimizing volume and installation impact, ensuring timely medical treatment and reducing manual operation complexity.
Implementation Method 1
The motor includes a stator, a rotor, a plurality of commutators, and at least three brushes. The stator has a plurality of permanent magnet poles. The rotor has a plurality of windings, and the rotor rotates relative to the stator.
Implementation Method 2
The screw is screwed into the actuation rod. The motor drives the screw rotating so that the actuation rod axially moves relative to the screw.
Implementation Method 3
The actuator with switchable releasing speed further includes a worm wheel and a worm gear. The worm wheel is connected to the screw. The worm gear has two ends, one end is connected to a shaft of the rotor of the motor and the other end is engaged with the worm wheel.
Data Source
AI summary
An actuator with switchable releasing speed includes an actuation rod, a screw, and a motor. The motor drives the screw rotating so that the actuation rod axially moves relative to the screw. The motor includes a stator, a rotor, a plurality of commutators, and at least three brushes. The at least three brushes have a positive brush, a negative brush, and at least one auxiliary brush. The positive brush is connected to a positive DC voltage. One of the negative brush and the least one auxiliary brush is adjusted to connect to a negative DC voltage so as to change a rotational speed of the rotor, thereby controlling a movement speed of the actuation rod. Accordingly, the releasing speed of the actuator is switchable.