Mamac Systems, Inc.

S Asim Gul

A temperature sensor approximates fluid temperature averaged across a location range by including an outer armour layer. Several resistance temperature detectors are spaced in an electrical circuit which is then protected in the outer armour layer. The outer armour layer is woven without any seam to enhance its longitudinal thermal conductivity. In the preferred weave, twenty-four stands of sixteen metal threads each are helically woven. The electrical circuit is sealed interior to the armour layer so any condensation or moisture within the armour layer does not affect the circuit. The armour layer is sealed on its ends to the sheathing of the underlying circuit, so the armour layer provides stress relief across the connections of the resistance temperature detectors to the circuit. The resulting sensor is robust and durable, as well as very flexible.

Armoured flexible averaging temperature sensor

A fluid sensor probe such as a temperature probe uses heat shrink tubing to seal and provide strain relief at a proximal end of the probe. The heat shrink tubing uses a layer of hot melt adhesive along its inside surface to form a strong bond and hermetic seal. The heat shrink tubing is applied as an inner tubing around circuit wires extending into the probe and as an outer tubing around the inner tubing and around the proximal end of the probe housing. Together the inner tubing and the outer tubing can hermetically seal a substantial gap between the probe housing and the circuit wires. In a fast response probe, prior to closing the distal end of the probe housing with an end wall, openings are punched in a side wall of the probe housing against a mandrel. The openings permit fluid flow to contact the sensing element within the probe housing. Heat shrink tubing can be used to seal the circuit wires and prevent leakage.

Method of making fluid sensor probe

A multipoint temperature sensor for measuring fluid temperature in a duct includes multiple thermistors of equal resistance, spaced apart in a circuit. Each thermistor has a positive lead and a negative lead for connecting electrically with the circuit. Wires connect the thermistors such that half of the thermistors are placed in parallel with the other half of the thermistors. The total number of thermistors in the circuit is a perfect square. Shrinkwrap fits over the thermistors and the leads. Tabs disposed on bridging clips bend around the shrinkwrap and the wires on either side of each thermistor such that the tabs do not overlap the leads. All the wires between adjacent thermistors are contained in a single, plenum rated sheathing.

Multiple point averaging duct temperature sensor

A photo expansion gas detector includes a radiation emitter, a sample gas, an expansion gas hermetically sealed in a chamber, and a capacitive diaphragm for sensing pressure changes. The radiation emitter may be constant or may be cycled on and off. Radiation passes through the sample and into the expansion gas. The expansion gas expands according to the intensity of the radiation received. The capacitive diaphragm is impacted directly by the expansion gas. The capacitive diaphragm deflects relative to a fixed capacitive plate, resulting in changes in capacitance representing expansion and contraction of the expansion gas. The electrical signal generated by the changes in capacitance represent changes in the gas composition of the sample. The electrical signals are then processed to activate control systems.

Photo expansion gas detector

A thermowell adapter secures a sheathed and flanged sensor within an internally threaded thermowell. The thermowell adapter has a head and a body extending from the head. The body of the thermowell adapter has external threading for mating with the internally threaded thermowell. A passageway within the head and body defines an axis coaxially with the external threading. The sheathed and flanged probe extends within the passageway such that a sensing element of the sheathed and flanged probe extends into the thermowell. An axial securement on the head prevents the sheathed and flanged probe from moving axially in the passageway. A rotational securement that is separate from the axial securement interacts in a mating relationship with squeeze locations on the sheathed and flanged probe to prevent the probe from rotating about its axis in the passageway.

Thermowell adapter

A sensor assembly for use with a separate control unit has a housing with a cradling bracket, a sensor, and a connection socket. The housing has a sensor face, sides, a cradling bracket and a lid. The sensor face defines a sensor opening and a flange connection surface. Sides extend from the sensor face and attach at adjacent edges to form an enclosure with a lid opening. The cradling bracket is within the enclosure. The lid is sized to fit the lid opening and adapted for releasable attachment to the enclosure. The sensor has a sensing element, a flange member, and electrical leads. The sensing element senses a parameter through the sensor opening. The flange member extends from the sensing element and is fixedly attached to the sensing element. The flange member attaches the sensor to the flange connection surface of the housing. Electrical leads extend from the sensing element and terminate in terminal ends. The connection socket is attached to the terminal ends of the electrical leads. The connection socket has openings for receiving wires from the control unit to electrically connect with the electrical leads of the sensor. The connection socket is sized to mate with and be cradled by the cradling bracket. The cradling bracket and the lid cooperate in a closed position to prevent the connection socket from moving during use.

Sensor assembly with housing for secure sensor connections

A pressure monitoring assembly includes an isolation valve assembly and a differential pressure sensor assembly. The rigid manifold has two pressure inlet ports which each communicate with respective pressure outlet ports through isolation valves. An equalization passage and valve connect the two pressure lines. The pressure sensor assembly is sized to mate directly with the monolithic manifold by having sensor inlet ports that line up with the pressure outlet ports. Pressure tight attachments releasably secure the pressure sensor assembly to the manifold, but are rigid to support the weight of the pressure sensor assembly. No bleeding valves are necessary. Orientation and the positioning and construction of the manifold effectively reduce the amount of heat transfer between the pressure lines and the pressure sensor(s).

Pressure sensor

A sheathed and flanged temperature probe is formed using a cylindrical sheath and a flange of the same metallic material. The cylindrical sheath is closed on one end and open on the other, and has a length at least an order of magnitude greater than its outer diameter. The temperature sensing element is inserted into the sheath, leaving wires protruding from the open end of the sheath. The sheath may contain an epoxy in the closed end to insulate and stabilize the sensing element. The central portion of the sheath remains empty except for wires connecting the sensing element to the electrical leads. The open end of the sheath is sealed around two electrical leads, enclosing the temperature sensing element from ambient conditions. The flange member is formed from a single piece of metal, cold drawn using an awl to form a continuous sleeve having an axis perpendicular to the planar surface of the flange. The sheath is inserted into the sleeve. The flange is secured to the central portion of the sheath solely using a press crimper, pressing inward over a majority of the circumference of the sleeve, leaving crimp edges extending on opposite sides of the sleeve. At least one planar surface of the flange may be sealed with a gasket.

Sheathed and flanged temperature probe

A pressure monitoring assembly includes an isolation valve assembly and a differential pressure sensor assembly. The rigid manifold has two pressure inlet ports which each communicate with respective pressure outlet ports through isolation valves. An equalization passage and valve connect the two pressure lines. The pressure sensor assembly is sized to mate directly with the monolithic manifold by having sensor inlet ports that line up with the pressure outlet ports. Pressure tight attachments releasably secure the pressure sensor assembly to the manifold, but a rigid to support the weight of the pressure sensor assembly. No bleeding valves are necessary. Orientation and the positioning and construction of the manifold effectively reduce the amount of heat transfer between the pressure lines and the pressure sensor(s).

Differential pressure sensor and isolation valve manifold assembly

An HVAC control unit is formed of a molded, electrically insulative material. The HVAC control unit has a wall plate and a cover plate. The wall plate attaches to a standard electrical box and has an opening for wires, and a cover plate attaches to the wall plate forming a sensor compartment. A vertical separation wall divides the sensor compartment into two chambers, namely, a temperature sensitive chamber and an electrical component chamber. Electrical contacts extend through the separation wall. The cover plate includes lower and upper ventilation openings to allow unforced air flow from the outside room through the temperature sensitive chamber. The vertical separation wall restricts air flow between the two chambers, closing the temperature sensitive chamber to the electrical component chamber. A gasket seals an edge of the vertical separation wall to further restrict air flow between the chambers. The temperature sensor is placed in the lower third of the temperature sensitive chamber. In the preferred embodiment, the HVAC unit extends into the room no more than one inch and is sized to no greater than four inches wide and six inches high. In one embodiment, the temperature sensitive chamber extends the full height from a bottom to a top of the sensor compartment. In another embodiment, the temperature sensitive chamber has a slanted top wall.

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Orono, MN, United States of America

S Asim Gul