Actuator Motor Casing Resin Bonding Torque Resistance

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Solution Overview

Problem

Conventional actuators for rolling up swimming pool covers face challenges in maintaining mechanical strength and resisting torque, especially when using plastic materials, due to weak bonding and risk of screw loosening or tearing, particularly in submerged installations where buoyancy forces are significant.

Innovation Solution

The actuator design incorporates an electric motor with an envelope and crowns that utilize an intermediate agent, such as polymerized resin, to fill the play between screws and bores, ensuring secure fixation and preventing misalignment or loosening, allowing for the use of a plastic motor casing without a mechanical 'tree line', thereby enhancing mechanical resistance and reducing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If plastic material is used for the motor casing and crowns to reduce cost, then manufacturing cost decreases, but mechanical strength and torque resistance deteriorate

Engineering Contradiction:
Improvemanufacturing costVSAvoidmechanical strength
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The patent combines plastic material with a polymeric adhesive to create a composite connection system. The adhesive fills the interface between plastic components and metal screws, creating a hybrid structure that leverages the cost advantage of plastic while compensating for its mechanical weaknesses through the bonding properties of the adhesive.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The polymeric adhesive acts as an intermediary substance between the plastic crowns/casing and the metal screws. It mediates the mechanical connection by filling gaps and providing bonding, allowing the plastic components to withstand torque loads without requiring expensive mechanical reinforcement structures.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of manufacture

If screws are used to fix crowns to the motor casing, then assembly is simplified, but screw loosening and misalignment occur due to play between screws and bores

Engineering Contradiction:
Improveassembly simplicityVSAvoidconnection stability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The polymeric adhesive serves as an intermediary that eliminates the play between screws and bores. It fills the gaps around the screws, preventing misalignment and loosening while maintaining the simple screw-based assembly method. This resolves the contradiction by adding a bonding medium that enhances reliability without complicating the assembly process.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The adhesive changes the physical parameters of the screw-bore interface by filling voids and creating a bonded connection. This transforms the loose mechanical fit into a rigid, stable connection, preventing screw loosening and maintaining alignment under operational loads.

Inventive Principle:
Principle #35Parameter changes

3Strength

If tight screwing is applied to ensure mechanical strength, then connection strength improves, but risk of tearing plastic material increases

Engineering Contradiction:
Improveconnection strengthVSAvoidmaterial tearing risk
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The polymeric adhesive acts as a stress-distributing intermediary between the screws and the plastic material. It spreads the clamping force over a larger area, preventing stress concentration that would lead to tearing. This allows adequate tightening to achieve strong connections without exceeding the plastic material's tear resistance.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The adhesive modifies the stress distribution parameters at the screw-plastic interface. By providing a compliant bonding layer, it redistributes the mechanical stresses, allowing the connection to achieve high strength while the plastic material remains within its elastic limit and avoids tearing.

Inventive Principle:
Principle #35Parameter changes

4Ease of manufacture

If play between screws and bores is left unfilled, then assembly tolerance is maintained, but screw loosening and misalignment occur quickly

Engineering Contradiction:
Improveassembly toleranceVSAvoidconnection durability
Core Design Contradiction:
Ease of manufactureVSDuration of action of stationary object

Solution Approach 1:

The polymeric adhesive fills the play between screws and bores, creating a permanent bonding structure that prevents screw loosening and misalignment. It maintains the assembly tolerance benefits while eliminating the durability issues associated with loose fits, as the adhesive locks the components in their correct positions.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The adhesive is applied in advance during assembly to fill the gaps before the screws are fully tightened and before operational loads are applied. This preliminary bonding action ensures that the connection maintains its integrity and prevents loosening throughout the service life of the actuator.

Inventive Principle:
Principle #10Preliminary action

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 strengthens the connection between the motor casing and crowns, enabling the use of plastic components without a mechanical reinforcement, resulting in a more economical and mechanically robust actuator that effectively resists torque and maintains stability over time.

Implementation Method 1

The intermediate agent is a polymerized resin

Methodology Applied
Scientific EffectPolymerization: Photopolymerisation

Data Source

PatentEP2816176B1Actuator for driving a winding tube of a pool cover, facility for winding a cover made up of such an actuator, and method for manufacturing such an actuator
Publication Date: 2016.03.23 RADIO ELECTRIQUE & MECANIQUE SIREM
  • EP2816176B1 patent drawingFigure 1
  • EP2816176B1 patent drawingFigure 2
  • EP2816176B1 patent drawingFigure 3

AI summary

This actuator for driving a pool cover winding tube (4) comprises an electric motor disposed inside the cover tube and capable of rotating the tube around a central axis, a housing (34) inside which the motor is located, and two rings (36) fixed on either side of the housing and comprising several holes (40) into which screws (38) are inserted with a certain clearance (J) and which are tightened into the housing. The clearance (J) between the screws (38) and the holes (40) of one or both rings (36) is filled by an intermediate agent (37) that secures the screws in the holes.