Wednesday, November 5, 2014

Negative Rate Belleville Disc Spring for Pressure Sensing

negative rate belleville spring
Conventional pressure switches incorporate constant-rate sensing technology (Bellows, Bourdon Tube, Spring Loaded Piston). Another technology available is the negative rate Belleville disc spring, which combines a Bellville disc with a fully adjustable helical spring and a diaphragm.

negative rate belleville spring
The advantage of this technology is minimized or eliminated effects caused by vibration, low temperature, high cycle life / premature wear, contact chatter and pump ripple. The switch is either on or off and there is no “teasing” of the electrical element. There are no moving parts except during actuation and de-actuation. The total movement is typically less than .010 inches.

In this design, the diaphragm is not a sensing element. It simply seals the media and transfers force to the disc spring, which responds instantaneously when system pressure reaches the set point.
negative rate belleville spring