Automatic temperature and humidity regulation – Ventilator type – Mechanical linkage actuated
Reexamination Certificate
1999-06-25
2001-01-23
Doerrler, William (Department: 3744)
Automatic temperature and humidity regulation
Ventilator type
Mechanical linkage actuated
C236S049300, C236SDIG001, C454S258000
Reexamination Certificate
active
06176435
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a thermally powered air diffuser and, more particularly, to a thermally powered variable air volume diffuser that regulates air volume delivery in response to air supply and room air temperature changes.
2. Description of the Prior Art
Numerous types of variable air volume (VAV) systems for controlling room air temperature are known and used, including fan-powered systems, VAV with radiation, VAV with reheat, heat-pump VAV, changeover/bypass VAV, and thermally powered VAV systems. Thermally powered systems typically employ air diffusers having “thermal motors” that open and close internal air flow dampers—so-called “smart diffusers.” Thermally powered smart diffusers have several advantages over the equipment comprising other types of VAV systems, including: (1) having self-contained systems for controlling room air supply without the need for dedicated wall and duct thermostats or additional electrical wiring, pneumatic piping, added system pressures; (2) low maintenance requirements and costs; (3) excellent comfort control, due to the fact that temperature control set points may be adjusted at the diffuser itself to provide proportionally modulating control within a restricted temperature span for a particular room or space; (4) reliability, due to a minimum of mechanical components and the entire absence of electrical components; (5) flexibility, allowing walls and partitions to be moved and office space reconfigured without costly reconfiguration of HVAC systems; (6) energy and cost savings, because no energy input is required to drive the system other than that already supplied by the heating and air conditioning system; and (7) low manufacturing and installation costs.
Thermally actuated variable air volume diffusers are well-known in the art. Notable examples include Vance U.S. Pat. No. 4,231,513, issued Nov. 4, 1980, and reissued Jun. 1, 1982, which discloses a diffuser for a conditioned air system for buildings incorporating a self-contained and integrated sensor actuator control system for varying the volume flow of conditioned air through the diffuser in response to changes in room air temperature. The sensor actuator structure for sensing the room air temperature and for modulating the conditioned air flow is entirely contained within the diffuser structure and is powered directly by the changes in room air temperature without auxiliary equipment or power systems. Additionally, Vance teaches a second integrated sensor that measures the temperature of the duct air and provides the actuating force to changeover and convert the operation of the diffuser from a cooling mode to a heating mode, or vice versa.
Brand U.S. Pat. No. 4,491,270 teaches an improvement over Vance. Brand discloses a diffuser comprising four thermal sensor actuators, including a first sensor responsive to changes in the room air temperature when cool air is supplied through the duct into the room. A second thermal sensor actuator is responsive to the duct air and is adapted to engage the first thermal sensor actuator when cool air is supplied through the duct and to disengage the first thermal sensor actuator when warm air is supplied through the duct. A fourth thermal sensor actuator is responsive to changes in the duct air temperature and brings the third thermal sensor actuator into engagement when warm air is supplied through the duct and to disengage the third thermal sensor actuator when cool air is supplied through the duct.
Noll U.S. Pat. No. 4,509,678 discloses a room air diffuser control mechanism which is operated by two thermally powered thermostatic actuator elements, one reacting to the room air temperature and the other reacting to the supply air temperature. When the supply air temperature is cool (e.g., less than 68° F.), the supply air element is retracted and its linkage system rendered inoperative. The room air element, through its linkage system, reacts to control the room temperature by varying the area of an air diffusion discharge opening. When the supply air temperature is warm (e.g., greater than 78° F.), the supply air element reacts to disengage the room air element linkage system and to move the air diffusion discharge opening to an adjustable, predetermined position. In this mode, the room air element does not affect the discharge opening regardless of the temperature of the room air.
Kline et al. U.S. Pat. No. 4,523,713 also teaches an improvement over Vance. However, whereas Brand discloses a diffuser having four thermal sensor actuators, Kline et al teaches a diffuser having three thermal sensor actuators. The first thermal sensor actuator is responsive to changes in the room air temperature and is engaged when cool air is supplied through the duct into the room. A third thermal sensor actuator is responsive to changes in the room air temperature and is engaged when warm air is supplied to the room. A second thermal sensor actuator brings either the first or second thermal sensor actuator into engagement with the diffuser when the appropriate temperature of air is supplied through the duct and disengages the thermal actuator not being used with the duct air temperature.
SUMMARY OF THE INVENTION
A thermally powered variable air volume diffuser is provided, comprising a diffuser housing defining an cylindrical upper chamber having an air inlet and a diffused air outlet defined by the opening at the lower portion of the diffuser housing from which conditioned air is supplied and diffused into a room. The air inlet is connected to an air supply duct. The housing includes an air discharge opening proximate to the lower end of the cylindrical upper portion. The discharge opening regulates the volume of air passing through the diffuser.
A thermal actuator assembly is mounted inside the upper cylindrical chamber and has a U-shaped chassis with a transverse axle rotatably mounted through apertures in its vertical sections. A first thermal actuator is mounted to the chassis at a first bracket integral with the chassis. The first actuator has a hollow cap containing thermoactive material and an integral hollow threaded cylindrical stem extending from the cap and threadably mounted to the first bracket. A first movable shaft is surrounded by the cylindrical stem.
A U-arm is pivotally mounted on the transverse axle, one arm extending beyond the transverse axle and including a second bracket to which a second thermal actuator is mounted with a second integral threaded stem. The second thermal actuator houses a second movable shaft.
A third thermal actuator is mounted to the base portion of the chassis through a third bracket and is disposed below the chassis. The third thermal actuator, structured like the first and second actuators, further includes a hollow cylindrical post and movable shaft, each extending upwardly from the cap and threaded stem beyond the base of the chassis. The stem of the third thermal actuator is threadably received by a first isolator bushing.
A fourth thermal actuator extends below the chassis, mounted to the horizontal base portion of the chassis. This actuator includes a hollow cylindrical center post housing a fourth movable shaft. As with the third thermal actuator, the stem of this actuator is threadably received in a second isolator bushing. The cap may include radial fins to increase the actuator's thermal sensitivity.
A flow controller disc is slidably mounted on the fourth actuator center post. The flow controller disc has a brim and an interior conical damper. A lever assembly is fixed to the transverse axle at one end and to the flow controller disc at the other.
A first radial tab member is affixed to the transverse axle, which extends outwardly from the back side of the chassis. Means for imparting a clockwise rotational force to the transverse axle is attached to the first radial tab member and the chassis. Second and third radial tab members at attached to the transverse axle at its middle. Force means connect the second radial tab member and U-a
Doerrler William
Johnson Larry D.
Johnson & Stainbrook LLP
Norman Marc
Stainbrook Craig M.
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