Magnetically sensed thermostat control

Details Magnetically sensed thermostat control Magnetically sensed thermostat control

2002-07-18

2004-05-25

Vortman, Anatoly (Department: 2835)

Electricity: electrothermally or thermally actuated switches

Thermally actuated switches

With bimetallic element

C337S366000, C324S207200

Reexamination Certificate

active

06741158

ABSTRACT:

TECHNICAL FIELD
The present invention is generally related to sensor methods and devices. The present invention is also related to temperature sensing methods and devices. The present invention is additionally related to thermostat control devices. The present invention is further related to magnetic sensor methods and devices. The present invention also relates to switching methods and devices, particularly thermostat control switching devices thereof.
BACKGROUND OF THE INVENTION
Thermostat control devices are often utilized in heating and cooling systems in buildings, homes, and industrial applications such as power plants. Thermostat control devices are required, for example, to control power to a furnace or air conditioner blower motor, which is typically an AC induction motor. In heating, ventilation and air-conditioning (HVAC) systems, such as home air conditioning systems, it is often desirable to change the fan speed or blower speed to control the amount of airflow through the system's evaporator coil. In addition, in the initial operation in an air conditioning mode, the blower operates at high speed to pump conditioned air, especially to higher floors. Then, when the comfort space or living space has cooled down, the fan speed can be reduced to avoid blowing cold air directly on human occupants.
A number of electrical switching applications require mechanical switches that are both efficient and reliable. These requirements arise commonly in electromechanical thermostats utilized in the thermostat control of heating and cooling systems in homes and buildings indicated above. In such configurations, coils of standard bi-metallic strips can form the switch actuation elements. For many years this thermostatic switching function has been performed by mercury bulb switch elements. Thermostat control devices in use today generally operate utilizing a bi-metallic strip that changes angularity with temperature, tilting a mercury switch so that the mercury can move to make or break contacts, using the self leveling nature of the mercury itself.
One of the problems associated with mercury-based switching devices is the mercury itself, which presents a number of dangerous environmental hazards, as well as danger to humans and animals. Mercury-based thermostat switching devices have been under heavy scrutiny from environmentalists to eliminate the use of mercury. Thus, it is only a matter of time before mercury-based thermostat switching devices fall entirely out of favor. An alternative solution must be found, particularly because it is anticipated that the use of mercury will soon be banned entirely.
Other solutions have included finding a replacement for mercury or employing metallic spheres rolling in a glass tube to come into contact with switching electrodes, imitating a mercury switch, although not very successfully. Other attempts have involved replacing the mercury switch with a reed switch. This particular approach has resulted in a number of accuracy problems. Other solutions have included the use of snap-action devices.
Snap-action switches have been utilized as control devices. The term “snap-action switch” generally refers to a low actuation force switch, which can utilize an internal mechanical apparatus to rapidly shift or snap the movable contact from one position to another to make or break electrical conduction between the movable contact and a fixed contact in response to moving an operating element of the switch, such as a plunger, a lever, a spring, or the like from a first to a second position. Typically, these switches require only a few millimeters of movement by the operating element to change the conduction state of the switch. Such switches generally operate at a current level of several amperes using the standard 24 VAC power which thermostats control.
When actuated by a low and slow actuation force, however, such as is provided by a thermostat's coiled bi-metallic strip, snap-action switches can occasionally hang in a state between the two conducting states, or can switch so slowly between the two conducting states that unacceptable arcing can occur when entering the non-conducting state. Either condition can give rise to unacceptable reliability and predictability of operation. Furthermore, these switches frequently have unacceptably large differentials. Current switches also contain a heating circuit that actually changes the bi-metallic strip by adding heat to it. The amount of heat applied is generally adjustable by use of an adjustable wire-wound resistor. In this sense, such devices do not truly respond to a change based on the room temperature. Additionally, mercury-based devices exhibit a weight problem associated with the use of mercury, which can affect the sensitivity of the device. The present inventors have thus recognized that a need exists for a temperature-sensitive switching device that responds directly to room air temperature, and one that also avoids the weight and environmental issues associated with mercury.
Based on the foregoing, the present inventors have concluded that a solution to such problems can be achieved through the use of Hall-effect sensors, which are sensor devices that operate according to the Hall effect. The Hall effect is well known in the magnetic sensing arts. Hall-effect sensors are typically based on the utilization of a Hall generator, which generally comprises a magnetic field-dependent semiconductor whose function rests on the effect discovered by Edwin Hall. This effect, known as the “Hall effect” is caused by the Lorentz force, which acts on moving charge carriers in a magnetic field. The Hall effect occurs when the charge carriers moving through a material experience a deflection because of an applied magnetic field. This deflection results in a measurable potential difference across the side of the material, which is transverse to the magnetic field and the current direction.
One of the first practical applications of the Hall effect was as a microwave power sensor in the 1950s. With the later development of the semiconductor industry and its increased ability for mass production, it became feasible to use Hall effect components in high volume products. Honeywell International Inc. (“Honeywell”), a company headquartered in Morristown, N.J., for example, has been a leader in Hall effect applications. In 1968, Honeywell's MICROSWITCH division produced a solid-state keyboard using the Hall effect. The Hall-effect sensing element and its associated electronic circuit are often combined in a single integrated circuit to form a Hall-effect sensor thereof. Note that the term “Hall-effect sensor” and “Hall sensor” are generally utilized interchangeably to refer to the same type of device. Thus, Hall sensors are well known in the magnetic sensing arts.
In the simplest form of a Hall sensor, a Hall element can be constructed from a thin sheet of conductive material with output connections perpendicular to the direction of electrical current flow. When subjected to a magnetic field, the Hall-effect element responds with an output voltage that is proportional to the magnetic field strength. The combination of a Hall-effect element in association with its associated signal conditioning and amplifying electronics is sometimes called a Hall-effect transducer.
A number of types of Hall-effect sensors are currently utilized in commercial, consumer and industrial applications. Honeywell, for example, produces a family of solid-state position sensors that include digital and analog Hall-effect position sensors, magnetoresistive digital sensors, Hall-effect vane sensors, gear tooth sensors, Hall-effect basic switch, and various types of magnets thereof. Such solid state position sensors are reliable, high speed, long life, sensors that are directly compatible with other electronic circuits. These sensors respond to the presence or the interruption of a magnetic field by producing either a digital or an analog output proportional to the magnetic field strength. Digital and analog “sensor-only” devices a

Affiliated with

Also associated with

Rating

Magnetically sensed thermostat control does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Magnetically sensed thermostat control, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Magnetically sensed thermostat control will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3194286