Bimetal Snap Disc Assembly With Integral Locking for Stable Switching

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Solution Overview

Problem

Existing temperature-dependent switches face challenges in production complexity, component damage, and mechanical instability due to the assembly of bimetal and spring snap-action disks, leading to defects and malfunctions.

Innovation Solution

A temperature-dependent switching mechanism featuring a bimetal snap disk, a spring snap disk, and an electrically conductive contact part with integral locking elements, allowing for a captive unit to be pre-produced as a semi-finished product, reducing components and assembly steps while ensuring mechanical stability and preventing damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the bimetallic snap-action disc is inserted as a loose individual part during manufacture, then the service life and switching point stability are improved, but the production complexity and assembly steps increase

Engineering Contradiction:
Improveservice life and switching point stabilityVSAvoidproduction complexity and assembly steps
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the bimetallic snap-action disc, spring snap-action disc, and contact part into a single integrated switching mechanism with integral locking elements. This merging reduces the number of separate components and assembly steps while maintaining the reliability benefits through the captive unit design that prevents component detachment during storage and transport.

Inventive Principle:
Principle #5Merging (Combining)

2Productivity

If the switching mechanism is pre-produced as a semi-finished product, then the productivity and cost-effectiveness are improved, but the risk of component detachment and damage increases

Engineering Contradiction:
Improveproduction efficiency and cost-effectivenessVSAvoidcomponent attachment stability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent incorporates locking elements that are formed integrally with the contact part during the pre-production stage. This preliminary formation of locking features allows the switching mechanism to be manufactured as a semi-finished product while ensuring that components remain securely attached during storage and transport, eliminating the risk of detachment.

Inventive Principle:
Principle #10Preliminary action

3Ease of manufacture

If traditional assembly methods are used for the snap-action discs, then the manufacturing flexibility is maintained, but the mechanical stability and defect rate are worsened

Engineering Contradiction:
Improvemanufacturing flexibilityVSAvoidmechanical stability and defect rate
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent employs locking elements that are formed integrally with the contact part, enabling the switching mechanism to assemble itself during the molding process. This self-service approach eliminates the need for separate assembly operations while ensuring consistent mechanical stability and reducing defects associated with traditional assembly methods.

Inventive Principle:
Principle #25Self-service

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 solution simplifies production, enhances mechanical stability, and prevents unintentional detachment of components, resulting in a reliable and cost-effective switching mechanism with improved service life and reduced defects.

Implementation Method 1

The temperature-dependent bimetallic snap-action disc is primarily responsible for the switch's temperature-dependent switching behavior. This is usually a multi-layer, active, sheet-metal component made of two, three, or four interconnected components with different thermal expansion coefficients.

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

Depending on the temperature, the bimetallic snap-action disc switches from its low-temperature configuration to its high-temperature configuration, similar to a hysteresis.

Methodology Applied
Scientific EffectHysteresis: Hysteresis

Implementation Method 3

The spring snap-action disk presses the movable contact part against a stationary counter-contact which is arranged on the inside of the switch housing on the cover part.

Methodology Applied
Scientific EffectElastic force: Elasticity

Data Source

PatentEP4310878B1Temperature-dependent switching device, temperature-dependent switch, and method for producing a temperature-dependent switching device
Publication Date: 2024.12.18 HOFSAESS MARCEL P
  • EP4310878B1 patent drawingFigure 1~2
  • EP4310878B1 patent drawingFigure 3~4
  • EP4310878B1 patent drawingFigure 5

AI summary

Temperature-dependent switching mechanism (10) for a temperature-dependent switch (100), comprising: a temperature-dependent bimetallic snap disc (12) having a first through-hole (18); a temperature-independent spring snap disc (14) having a second through-hole (20); and an electrically conductive contact part (16) having a base body (22) extending through the first through-hole (18) and the second through-hole (20). The contact part (16) has a bearing shoulder (24) projecting radially from the base body (22), a first locking element (26) projecting radially from the base body (22) and arranged on a first side of the bearing shoulder (24), and a second locking element (28) projecting radially from the base body (22) and arranged on a second side of the bearing shoulder (24) opposite the first side.The temperature-dependent bimetallic snap disc (12) and the spring-loaded snap disc (14) are arranged between the locking elements (26, 28) and the support shoulder (14) and are held captive by these elements, but with some play, against the base body (22) of the contact part (16). The contact part is formed in one piece, with the base body (22) being integrally connected to the support shoulder (24), the first locking element (26), and the second locking element (28).