Rotor Clip Wave Springs Prevent Frequently Encountered Effects of Thermal Expansion

Unwanted movement, vibration, and noise are frequently encountered effects of thermal expansion. In pre-loading components, such as sensors, this can lead to inaccurate sensor readings or even complete application failure. This can be solved by a better spring element – a wave spring.

Thermal Expansion is a common problem in applications exposed to high temperatures or that use materials sensitive to temperature changes. A common problem is internal components becoming loose after external components expand due to an increase in operating temperature, causing unwanted movement, vibration and noise.

To avoid this situation, design engineers pre-load components with spring elements that compensate for thermal expansion and fix the component tightly in place. However, not all spring elements are suited to easily compensate for axial endplay caused by thermal expansion.

Rotor Clip was asked to find a solution to preload a sensor used in an automotive exhaust gas system. During regular operation, the exhaust system heats up and cools down in different intervals, resulting in a possible loose fit of the sensor in its housing.

In the original design, the sensor case was pre-loaded by a conventional disc spring. After several tests, it was discovered that the disc spring could not offer the required levels of work height needed to keep the sensor seated tightly in the application.

Rotor Clip solved this problem with a single-turn wave spring made from A286 stainless steel conforming to DIN Material No. 1.4980. The wave spring solution Rotor Clip provided solves three application challenges at once:

  1. It offers sufficient travel to compensate for the maximum thermal expansion within the application.
  2. Due to the material choice (A286 stainless steel) the spring is less prone to fatigue caused by the application’s operating temperatures and, therefore, prolongs total application life.
  3. It simplifies the assembly process by eliminating a secondary assembly step. The original design required that the disc spring element be held in place before the sensor was seated inside the application housing. In contrast the wave spring “clings” to the inside of the housing in which the sensor sits, eliminating the necessity for this secondary step.

In summary, wave springs deliver a high degree of versatility to the designer seeking to solve particular application problems. The flexibility afforded by the wave spring regarding materials, configurations and styles, makes it a critical “go to” component for the engineer searching for viable alternatives to traditional ways of accomplishing effective component pre-load.

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