Helical Spring Brake Actuator for Home-Automation Screens
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Solution Overview
Problem
Conventional spring brake designs for electric actuators in home-automation systems experience secondary braking torque during screen raising, leading to over-dimensioning of motors, as the secondary braking torque is added to the load torque, making the system less efficient and requiring more power to operate.
Innovation Solution
The electric actuator incorporates a helical spring brake design where the inlet part and outlet part are in direct contact only during screen raising, eliminating secondary braking torque by transmitting drive torque through multiple contact surfaces, balancing the forces to reduce radial stress and eliminate secondary braking torque during lowering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a conventional spring brake design is used, then the brake provides main braking torque through spring friction, but secondary braking torque is generated during screen raising due to asymmetrical force on the outlet part, leading to motor over-dimensioning
Solution Approach 1:
The invention intentionally introduces asymmetry through the transmission element geometry to counterbalance the asymmetrical force generated by the spring brake. The transmission element has a first contact surface oriented at a first angle and a second contact surface oriented at a second angle, creating an asymmetrical force distribution that generates a compensating radial component to cancel the secondary braking torque.
Solution Approach 2:
The invention applies a counterbalancing force through the transmission element to offset the harmful secondary braking torque. The asymmetrical orientation of contact surfaces creates a radial force component that acts in opposition to the secondary braking torque, effectively neutralizing its effect during screen raising operation.
2Power
If the inlet part and outlet part are in direct contact during screen raising, then drive torque is transmitted efficiently, but secondary braking torque is generated due to asymmetrical force distribution
Solution Approach 1:
The transmission element incorporates asymmetrical contact surfaces with different orientations to create a force distribution that counterbalances the asymmetrical secondary braking torque. The first contact surface and second contact surface are oriented at different angles to the rotation axis, generating compensating radial forces.
Solution Approach 2:
The invention changes the geometric parameters of the transmission element, specifically the angles of contact surfaces relative to the rotation axis. By optimizing these angular parameters, the system achieves both efficient torque transmission and cancellation of secondary braking torque through controlled asymmetrical force distribution.
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 design optimizes motor dimensioning by eliminating secondary braking torque during screen raising, allowing for efficient operation regardless of the screen's direction, enhancing the actuator's versatility and reducing the need for specific motor mounting configurations.
Implementation Method 1
a friction part having a substantially cylindrical friction surface against which at least one turn of the helical spring bears radially
Data Source
AI summary
This electric actuator for driving a home-automation screen is provided with a spring brake (105) comprising a helical spring (130), a friction part (140) having a friction surface (141) against which the helical spring (130) bears radially. Said brake further comprises an inlet part (110) suitable for driving the spring in rotation in a direction reducing the contact force between the spring (130) and the friction part (140), and an outlet part (120) connected to the screen.While the screen is being lowered, the inlet part (110; 210) drives the spring (130; 230) in rotation with the contact force being decreased to the extent that the outlet part (120; 220) is released in rotation, without direct contact between the inlet part and the outlet part. The inlet part (110; 210) has at least two contact surfaces (113a, 113d; 213b, 217c) suitable for transmitting drive torque (CM) for raising the screen (2), by direct contact, to at least two corresponding contact surfaces (123a, 123d; 223b, 227a) of the outlet part (120; 220).