Patent Application
20080238603
Mounting thermal switches on tubes for purposes of temperature monitoring and thermal control such as those in satellites or other devices has historically been a challenge. One present method for mounting thermal switches to tubes uses a corrosion resistant (CRES) radius matching mounting adaptor that is attached to the tube using thin sheet metal straps. Although this method and other methods that use screws with backing plates are effective for holding the thermal switch to the tube, the CRES is typically quite heavy and is not the most effective thermal conductor. Also, the sheet metal straps at times do not hold the sensor as securely as some applications require. Another concern in space applications is that fastener hardware may loosen or dislodge thereby causing problems.
Therefore, there exists a need for a light weight, more easily attachable, and more thermally conductive device for attaching thermal switches to tubes. Improved thermal conductivity of the attachment device would increase the effectiveness and accuracy of the thermal switch.
The present invention provides a device for attaching a thermal switch to a tube. The device includes a base having first and second sides and a thermal switch cavity located between opposing ends of the base on the first side. The cavity is configured to receive a thermal switch. Two straps attach the device to a tube at the opposing ends. The second side is formed to receive a tube, such as a fuel line, of a predefined radius.
In one aspect of the invention, each of the ends includes at least one groove for receiving one of the straps. The straps are a low outgassing material.
In another aspect of the invention, the base, ends, and cavity include aluminum with a low electrical resistance, chemical conversion coating.
In still another aspect of the invention, two devices are attached on opposing sides of the tube using the two straps.
Preferred and alternative embodiments of the present invention are described in detail below with reference to the following drawings:
Each of the flanges 40 includes a pair of opposing grooves 42 that begin at the surface of the topside of the base section 30 near a longitudinal axis of the topside and extends at an angle to respective sides of the base section 30. A second side of the base section 30 that is opposite of the first side of the base section 30 is formed to receive a tube of a particular predefined radius of curvature.
Each pair of grooves 42 at a flange 40 receives a single strap 50 that is tightened around both the flange 40 and tube 28. In one embodiment, the straps 50 are formed of a low outgassing material, such as a fluoropolymer. In another embodiment, the strap 50 is formed of stainless steel or any other material that securely holds the device 20 to the tube 28 and meets the requirements for whatever environment the device 20 will be used in. The straps 50 are held in place similar to common tie straps.
The attachment device 20 is preferably formed of aluminum or some other highly thermally conductive metal.
The thermal switch receiving section 36 is shaped to receive a thermal switch 26. The thermal switch 26 is attached within the section 36 using known materials, such as a thermally and electrically conductive, low outgassing epoxy.
In another embodiment, a thermally and electrically conductive, low outgassing epoxy is also used on the second side of the attachment device 20 for additional bonding to the tube 28.
While the preferred embodiment of the invention has been illustrated and described, as noted above, many changes can be made without departing from the spirit and scope of the invention. Accordingly, the scope of the invention is not limited by the disclosure of the preferred embodiment. Instead, the invention should be determined entirely by reference to the claims that follow.
