Patent Application
20090230278
Sensing devices or sensors used for the detection of fire, smoke and heat as well as detecting environmental gas levels, for example, carbon dioxide or carbon monoxide, are often used in special applications which require shock and vibration resistance. For example, in military uses, such as on shipboard or in aircraft and combat vehicles, such sensors need to be able to withstand substantial shock and vibration to which they are exposed. Current designs for ruggedized sensors include a cage or basket mounted near the sensor heads to capture and retain sensor components which may become separated during exposure to extreme vibrations and shock, such as explosions and the like. However, such a device does not adequately protect the sensor when exposed to such extreme conditions.
The present device is directed to a shock and vibration resistant sensor mount employing a pre-stressed hinge clamping assembly in which the sensor is mounted. A hinge assembly forms a hinge connection between a base plate and a clamp lid. A releasable clamp assembly, secured to the base plate and the clamp lid opposite the hinge assembly, provides for securely clamping the sensor housing and sensor between the base plate and the clamp lid. In a preferred embodiment, an elastomeric pad is compressed between the clamp lid and the sensor housing when the mounting assembly is engaged to clamp the sensor housing. Preferably, the clamp assembly is a latch-type toggle clamp. In another preferred embodiment, the base plate is unreleasably or permanently attached to the sensor support housing structure.
Referring to the drawings, there is shown a sensor mount assembly 10 with a sensor 30 and sensor housing structure 26 clamped between base plate 12 and clamp lid (top restraint plate) 14. At one side of the assembly is the hinge assembly 20 which is secured to and between clamp lid 14 and base plate 12. Opposite the hinge assembly 20 is a releasable clamp assembly 25.
The clamp lid 14 comprises a cover plate having a shape configured to exert force against the upper surface of a sensor or sensor housing as shown in the drawings. Preferably at least a portion of the clamp lid is shaped to conform to the shape of the sensor or sensor housing surface against which the clamp lid is forced. Such a configuration is seen in
The base plate is preferably a circular configured to engage the bottom of the sensor housing structure opposite the clamp lid. The base plate is preferably generally flat but also may be provided with features such as ribs, ridges, grooves or channels for engaging, supporting and/or being secured to the sensor housing structure. The base plate is also provided with extensions at opposite positions for being secured to the hinge assembly and clamping assembly, respectively, as shown in the drawings. Other base plate shapes or designs may be used so long as there is necessary and intended cooperation with the other sensor mount assembly components as described.
In the embodiments shown in
Opposite the hinge assembly 20 is a clamp assembly 25 for securing and forcing the base plate and clamp lid in clamping engagement against the sensor and sensor housing. The clamp assembly illustrated is a latch-type toggle clamp 16 which includes a toggle lever 21 and a U-shaped clamp 23 member which engages a lip 13 formed at the end of clamp lid or which is secured to an extension 17 of clamp lid 14. Clamp body 16 is secured to the base plate 12 at hinge 19. Such a latch-type toggle clamp, its components and operation are well known to those skilled in the art. However, other types of clamps and clamp assemblies may be used instead. Any such clamp assembly design configured to releasably connect the base plate and clamp lid in clamping engagement with a sensor and sensor housing may be used.
In a preferred embodiment, an elastomer pad is used between the clamp lid and sensor housing, preferably positioned on the underside of the clamp lid so that it can forceably engage the upper sensor housing surface to be compressed between the sensor housing surface and the clamp lid. The elastomer pad is preferably a flat, donut-shaped pad secured around the perimeter of the opening in the center of the clamp lid exposing the sensor head. Examples of suitable elastomer pad materials include silicone rubber, natural rubber, neoprene, EPR, EPDM, fluoroelastomers (Viton™), SBR, etc. ABR (polyacrylic rubber) resists hot oils and solvents whereas fluoroelastomers (FPM) have excellent solvent and chemical resistance, as well as continuous use at temperatures as high as 400° F. Preferably, the clastomeric pad is donut-shaped, leaving the sensor exposed through a large opening at the top of the clamp lid.
As also illustrated, particularly in
The clamping force exerted against the sensor housing by the closed clamp of the base plate and the clamp lid is in a range of between about 10 pounds and about 250 pounds, preferably between about 20 pounds and about 200 pounds, and most preferably between about 50 pounds and about 150 pounds. Again, it is preferred to use a two point hinge assembly to best create the clamp force uniformly between the two mount assembly clamp components.
The preferred materials of which the sensor mount assembly components are fabricated include plastics of suitable strength, capable of exerting and maintaining such clamp force configurations, all grades of aluminum, carbon steel and stainless steel also being preferred.
The shock resistant sensor assembly described hereinabove may be used not only with traditional temperature, smoke, and fire sensing license, but may also be used for mounting cameras, electronic equipment, and other sensing components and devices which operation may be compromised when exposed to shock and vibration.
