Apparatus and method for isolating a temperature sensing device in a thermostat

An improved thermostat is provided that comprises a first wall disposed within the thermostat, which partitions off a portion of the interior space to form a compartment along a side wall of the thermostat that is separated from the rest of the thermostat's interior space. The thermostat includes a second wall that is adjacent to and spaced from the first wall, so as to define an insulating space between the compartment and the rest of the interior space. The thermostat further includes a first aperture that permits communication of airflow in a lower portion of the compartment, and a second aperture that permits communication of airflow at an upper portion of the compartment. A temperature sensing element is disposed within the compartment defined by the first wall. The temperature sensing device is thermally insulated from heat generated in the interior of the thermostat by the insulating space between the compartment and interior space.

FIELD

The present disclosure relates to thermostats, and more particularly to temperature sensors within digital thermostats for controlling HVAC systems.

BACKGROUND

SUMMARY

Various embodiments are provided of an improved thermostat having opposing housing portions that mate to enclose a circuit board therein, which embodiments provide for improved sensing of ambient temperature. One embodiment of an improved thermostat comprises a first wall disposed within the interior space of the housing, which partitions off a portion of the interior space to form a compartment along a side wall of the housing that is separated from the rest of the interior space in the housing. The thermostat includes a second wall disposed within the interior space of the housing, which is adjacent to and spaced from the first wall so as to define an insulating space between the compartment and the rest of the interior space in the housing. The thermostat further includes a first aperture disposed in the housing that permits communication of airflow in a lower portion of the compartment, and a second aperture disposed in the housing that permits communication of airflow at an upper portion of the compartment. A temperature sensing element is disposed within the compartment space defined by the first wall. The temperature sensing device is thermally insulated from heat generating devices in the thermostat's interior space by the insulating space disposed between the compartment and the interior space in which the heat generating devices are disposed.

DETAILED DESCRIPTION

Referring toFIGS. 1-6, a first embodiment of an improved thermostat100is shown that includes a temperature sensing element within a compartment106inside the thermostat. The thermostat100includes a heat generating component, such as an electrical switching device, that is beneath the thermostat's cover120. The switching device may be configured to switch electrical power to a load, for example, and generates heat that is dissipated into the interior space of the thermostat housing. Such heat can negatively affect the ability of a temperature sensing element of the thermostat to accurately sense the ambient temperature of the space the thermostat is controlling.

Accordingly, one first embodiment of an improved thermostat100shown inFIGS. 1-6includes a base portion102and a cover portion120that mate to form a housing that includes a circuit board (shown inFIG. 6). Referring toFIG. 6, the thermostat100comprises a first wall104disposed within the interior space110, which partitions off a portion of the interior space110to form a compartment106along a side wall103of the thermostat100. The compartment106is thereby separated by the wall104from the rest of the interior space110. The thermostat100further includes a second wall108disposed within the interior space110of the thermostat, which is adjacent to and spaced from the first wall104so as to define an insulating space112(seeFIG. 7) between the compartment106and the rest of the interior space110of the thermostat100. The thermostat100further includes a first aperture114in the thermostat near the lower portion of the compartment106. This first aperture114permits communication of airflow in a lower portion of the compartment106. The thermostat100includes a second aperture116disposed in the thermostat above the first lower aperture114, where the second upper aperture116permits communication of airflow at an upper portion of the compartment106.

A temperature sensing element140is provided that includes electrical leads142extending to a circuit board130. The temperature sensing element140is disposed within the compartment106that is formed by the first wall104, which may depend from the base portion102or the cover portion120. The first wall104may be a single wall that depends from either one of the opposing housing portions, and may further extend into the other opposing housing portion, to thereby partition off the compartment from the rest of the interior space110of the thermostat when the housing portions are assembled. It should be noted that the temperature sensing element140, or the circuit board130, or both, may be disposed between the base portion102and cover portion120, or alternatively disposed within one housing portion or the other.

Because of the thermal generating device within the interior space of the thermostat, the heated air surrounding the device rises upward and escapes through vents152in the top of the thermostat (seeFIG. 2). This heated air escaping the top of the thermostat housing creates a chimney effect that draws ambient air in through vents154(seeFIG. 4) in the bottom of the thermostat. The heated air rising through the thermostat creates an upward draft of airflow below the thermostat. In addition to the upward draft that pulls heat out of the interior of the thermostat, ambient air is also permitted to pass through the first lower aperture114leading to the compartment106, and to pass through the second upper aperture116within the compartment106. Accordingly, the positioning of the compartment106along the sidewall103of the thermostat with the second aperture116disposed above the first aperture114permits the temperature sensing element140to sense the temperature of the ambient air flowing through the compartment106. Moreover, the temperature sensing element140accurately senses temperature without being affected by heat generating devices within the interior space of the thermostat. This is because the temperature sensing device is thermally insulated from heat generating devices by the insulating space disposed between the compartment and the remaining interior space in which said heat generating devices are disposed.

Referring toFIG. 7, a second embodiment of a thermostat200is shown. In the second embodiment, the thermostat200comprises a base portion102and a cover portion120that mate to form a housing in which a circuit board130is included. The second embodiment includes a temperature sensing element140that is connected to the circuit board130.

The base portion102has sidewalls103defining an interior space110, and a first wall104and second wall108disposed therein. The first wall104is disposed within the interior space110of the base portion102, and partitions off a portion of the interior space110to form a compartment106along a sidewall103of the base portion102that is separate from the rest of the interior space110. The second wall108is disposed within the interior space110, and is adjacent to and spaced from the first wall104so as to define an insulating space112between the compartment106and the rest of the interior space110. A first lower aperture114is disposed in the base portion sidewall, where the first lower aperture114permits communication of airflow in a lower portion of the compartment106. A second upper aperture116is disposed in the base portion sidewall103above the first lower aperture114, where the second upper aperture116permits communication of airflow at an upper portion of the compartment106. It should be noted that the at least one lower aperture114or vent opening in communication with a lower portion of the compartment may comprise at least two or more apertures, and the at least one upper aperture116or vent opening in communication with an upper portion of the compartment may comprise at least two or more upper apertures.

The cover portion120also has sidewalls defining an interior space, and a first wall122and second wall124therein. The first wall122is disposed within the interior space of the cover portion120, which partitions off a portion of the interior space to form a compartment106′ that is separate from the interior space and aligned with the compartment106in the base portion102. Specifically, when the base portion102and the cover portion120are assembled, the cover compartment106′ is in corresponding alignment with the base compartment106. A second wall124is disposed on the cover120, and is adjacent to and spaced from the first wall122so as to define an insulating space112′ between the compartment106′ and the rest of the cover portion120. The cover second wall122is in corresponding alignment with the base second wall108, such that the cover insulating space112′ is in alignment with the insulating space112of the base portion102.

The thermostat200includes a temperature sensing element140disposed within the compartment space106defined by the base portion102and cover portion120. The temperature sensing element140has electrical leads142extending to a circuit130between the first and second walls104,108in the base portion102, and the first and second walls122,124in the cover portion120. The positioning of the compartment106along the sidewall of the thermostat200, with the second upper aperture116disposed above the first lower aperture114permits the sensing element140to accurately sense the temperature of the ambient air flowing through the compartment106, without being affected by heat generating devices within the interior of the thermostat200. This is because the temperature sensing device140is thermally insulated from heat generating devices by the insulating space112disposed between the compartment106and the remaining interior space110in which the heat generating devices are disposed.

The thermostat200further includes at least one electrical component150disposed within an interior space110that is partitioned off from the compartment106, where the heat generated by the at least one electrical component150is insulated from the compartment106by the insulating space112. The at least one electrical component150may be a transformer, for example, or the at least one electrical component may further be another electrical component, such as a switch device configured to switch a line voltage source to a load. The switch may be a Field Effect Transistor (FET), or a solid-state type of switching device, such as Triac device170shown inFIG. 10. The thermostat200may further include a heat sink160associated with the switch, where the heat sink160is disposed within a portion of the interior space110that is removed from the compartment106, or within a subsection of the interior space. The heat sink160is positioned away from the compartment106, such that heat dissipated by the transformer, the switch, and the heat sink160is insulated from the compartment106by the insulating space112.

The thermostat200further comprises a series of vent holes152,154above and below the thermostat200to permit airflow into and out of the interior space110of the thermostat200. The thermostat200also includes a first aperture156or vent opening disposed in the base portion102that permits communication of airflow in a lower portion of the insulating space112, and a second aperture158or vent opening disposed in the base portion102or side wall103permitting communication of airflow at an upper portion of the insulating space112. The electrical component may generate an amount of heat that is sufficient to cause the air within the interior space110to rise and create an updraft of air flow through the vent holes152in the thermostat200. In addition to the upward draft that pulls heat out of the interior of the thermostat, ambient air is also permitted to pass through the first lower aperture114leading to the compartment106, and to pass through the second upper aperture116within the compartment106. Accordingly, the positioning of the compartment106along the sidewall103of the thermostat with the second aperture116disposed above the first aperture114permits the temperature sensing element140to sense the temperature of the ambient air flowing through the compartment106. The lower vent openings156and upper vent openings158leading to the insulating space112also permit entry of ambient air into the insulating space112. This communication of ambient air to the insulating space112helps to convey heat out of the insulating space112.

Referring toFIGS. 8-10, a third embodiment of a thermostat300is shown. The thermostat300includes opposing housing portions that mate to enclose a circuit board130therein. One portion120of the thermostat300housing shown inFIG. 9has interior walls132within the interior space110that define a receiving area for the circuit board130. The thermostat housing portion102shown inFIG. 10includes a first wall104disposed within the interior space110of the thermostat housing portion102, which partitions off a portion of the interior space110to form a compartment106along a sidewall of the thermostat housing portion102that is separated from the rest of the interior space110. The thermostat housing portion102further includes a second wall108disposed within the interior space110, which is adjacent to and spaced from the first wall104in the thermostat housing portion102, so as to define an insulating space112between the compartment106and the remaining interior space110of the thermostat housing portion102. A first aperture114is disposed in a sidewall of the thermostat housing portion102, where the first aperture114permits communication of airflow in a lower portion of the compartment106. A second aperture116is disposed in the sidewall of the thermostat housing portion102above the first aperture114, where the second aperture116permits communication of airflow at an upper portion of the compartment106.

A circuit board130positioned within the housing portion120is configured to be received against the first wall104and the second wall108of the thermostat housing portion102, to thereby form an enclosure space between the circuit board130and the compartment106formed within the thermostat housing portion102by the first wall104. The circuit board130includes a heat generating component150that is disposed within the remaining interior space110of the thermostat housing portion102, which is separated from the compartment106by the insulating space112. A temperature sensing element140is disposed within the enclosure or compartment between the circuit board130and the compartment space106formed within the thermostat housing portion102by the first wall104. The temperature sensing element140has electrical leads142extending to the circuit board130, whereby the temperature sensing element140is thermally insulated from the heat generating component150within the interior space110of the thermostat housing102by the insulating space112.

Because of the thermal generating device within the interior space of the thermostat, the heated air surrounding the device rises upward and escapes through vents152in the top of the thermostat (seeFIG. 2). This heated air escaping the top of the thermostat housing creates a chimney effect that draws ambient air in through vents154(seeFIG. 4) in the bottom of the thermostat. The heated air rising through the thermostat creates an upward draft of airflow below the thermostat, which causes ambient air to flow through the first lower aperture114and enter into the compartment106, and to flow through the second upper aperture116and out of the compartment106.

Accordingly, the positioning of the compartment106along the sidewall of the thermostat housing102, with the second aperture116disposed above the first aperture114permits the temperature sensing element140to accurately sense the temperature of the ambient air flowing through the compartment106, without being affected by heat generating devices in the interior of the thermostat. This is because the temperature sensing device140is thermally insulated from heat generating devices150by the insulating space112disposed between the compartment106and the remaining interior space110in which the heat generating device150is disposed.

It will be understood by those skilled in the art that the insulated temperature sensing element provided by the present design may be employed in any thermostat that is used or designed to control a cooling load or a heating load. Accordingly, it should be understood that the disclosed embodiments of a latching relay control circuitry, and variations thereof, may be employed in any apparatus utilizing one or more latching relays for controlling one or more loads.