Patent Application
20050013597
The invention relates generally to a method and apparatus for mounting and cooling electrical devices that generate heat. More specifically, the invention relates to the mounting and cooling of a switching device, such as a triac.
A storage-type water heater typically comprises a permanently enclosed water tank, a cylindrical shell coaxial with and radially spaced apart from the water tank to form an annular space between the outer wall of the water tank and the inner wall of the shell, and insulating material in at least a portion of the annular space for providing thermal insulation to the water tank. The water tank has various appurtenances such as inlet, outlet, and drain fittings. Additionally, the water heater is provided with a water heating and temperature control system. In electric water heaters, the water heating and temperature control system includes an electrical resistance heating element.
Modern electric water heating and temperature control systems typically further include an electronic thermostat. The electronic thermostat closes a switch to allow electrical power through the electrical resistance heating element when water in the tank is sensed to be below a selected set-point temperature, and opens the switch to stop electrical power from passing through the electrical resistance heating element when the water in the tank is at or above the set point temperature. The switch is an electrical component that generates heat during use. The generated heat can interfere with the reliability of and the function of the switch. It would be beneficial to provide a way to dissipate the generated heat to ensure the proper operation of both the switch, and any other electrical components surrounding the switch.
Accordingly, and in one embodiment, the invention provides a water heater connectable to a power source. The water heater includes a vessel having an exterior surface, and a thermally conductive mounting device coupled to the exterior surface. The mounting device includes a base having a first surface configured to substantially follow the shape of an exterior surface of the vessel, a second surface, and a heat dissipating element coupled to the base. The water heater also includes a controller configured to selectively generate a signal based on a temperature of water in the vessel. A switch is connectable to the power source, connected to the controller, and coupled to the second surface of the base. The switch conducts power from the power source in response to the signal. The water heater also includes a heating element connected to the switch to receive the power.
In another embodiment, the invention provides for a heat dissipation device adapted to receive a heat-generating component and to couple to an exterior surface of a heat sink. The heat dissipation device includes a base having a first surface configured to substantially follow the shape of the exterior surface of the heat sink, and a second surface. The heat-generating component couples to the second surface of the base. The heat dissipation device includes a thermally conductive, electrically dielectric material to conduct heat from the heat-generating component to the heat sink.
In yet another embodiment, the invention provides for a water heater having a water tank with an arcuate exterior surface, and a thermally conductive mounting device coupled to the exterior surface of the water tank. The mounting device includes a base having an arcuate first surface and a second surface. A heat-dissipating element is coupled to the base. The water heater further comprises a switch coupled to the second surface of the base. In one construction, the water heater further comprises a second switch coupled to the second surface, and the second surface includes a channel between the first and second switches.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims and drawings.
Before any aspects of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including,” “comprising,” or “having” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. The terms “connected,” “coupled,” and “mounted” and variations thereof herein are used broadly and, unless otherwise stated, encompass both direct and indirect connections, couplings, and mountings. In addition, the terms connected and coupled and variations thereof herein are not restricted to physical and mechanical connections or couplings.
A heating element 16 extends through the wall of the water tank 11. In the illustrated embodiment, the heating element 16 is an electric resistance heating element. However, other types of heating elements can be used. The temperature control circuitry controls the heating of the water. The temperature control circuitry includes a controller (in control box 17), a temperature sensor assembly 18, and the heating element 16. In one construction, the temperature control circuitry includes a burst control circuit for providing power to the resistance heating element in bursts. The details of a burst control circuit are described in U.S. patent application Ser. No. 09/752,477, entitled PROPORTIONAL BAND TEMPERATURE CONTROL FOR ONE OR MORE HEATING ELEMENTS, filed Jan. 2, 2001, the entire disclosure of which is incorporated herein by reference. However, the temperature control circuitry can use other circuitries and other methodologies for heating the water.
In some constructions, the temperature control circuitry in control box 17 includes a programmable real time clock. Peak or off-peak energy demand periods or vacation operation cycles are programmed into the control cycle for the heating element. Additionally, a pressure sensor, temperature sensor, mineral deposit sensor and/or sensor for detecting the presence of water could be added. In one method of operation of the water heater 10, the control circuit is programmed to disconnect power from the heating element when predetermined conditions or limits are detected.
Referring again to
The temperature sensor assembly 18 is connected to the controller, for example, by an electrical wire 19. The controller is a known control system in the art that is in communication with the heating element 16 and the temperature sensor assembly 18 and generates a signal activating the heating element in response to the temperature sensed by the sensor assembly 18. The controller can include an integrated circuit, a programmable device, discrete circuit elements, a processor and memory, and similar components.
The temperature control circuitry also includes a switching device (or simply a switch), which may be part of the controller. The switching device is coupled to the outer wall of the vessel, i.e., the tank 11 or the shell 12, to selectively supply power to the heating element. The details of the switching device will be discussed in detail below.
The second surface 32 of the mounting device includes a mounting platform 36 for receiving a heat-generating component. The platform 36 can be flush with, or project upwardly from, the second surface 32. The platform 36, which can be considered a surface, is preferably similar in shape to the heat-generating component and in some constructions can be the same shape as the heat-generating component. In other constructions, the second surface 32 can include a flat receiving portion 38 such that the heat-generating component can be coupled directly to the second surface 32. The flat receiving portion 38, which can also be considered a surface, may be integral with or recessed into the second surface 32 (see
In the illustrated construction, the heat-generating component is a switching device, such as a thyristor or a triac 40.
The base 28 also includes at least one heat-dissipating element, such as a heat-dissipating fin 48. In the illustrated embodiments, a plurality of fins 48 are coupled to the base 28. It is understood that the fins can also be integrally formed with the base, such as by molding. The base 28 also includes a terminal block 52. The terminal block 52 includes electrical terminal connections 56 molded into the block 52. Conductors can also be molded into the base to couple the triac 40 to the connections 56 to provide an electrical pathway between the triac 40 and an electrical wire 60. The electrical wire 60 (see
Another water heater 160 embodying the invention is shown in
As shown in
When two heating elements are utilized in a water heater, it may be necessary for the controller to include two triacs 40, 40′. With reference to
As further illustrated in
With reference to
As a signal runs through the triacs 40, 40′, the triacs 40, 40′ consume energy and generate heat. If this heat is not dissipated, it can cause run away conditions in the triacs 40, 40′, causing the triacs 40, 40′ to stay on continuously, overheat, and/or eventually burn out. The mounting device 26 dissipates this heat in two ways. First, heat is dissipated by the fins 48 coupled to the second surface 32 of the mounting device 26. Air passing over the surfaces of the fins 48 will dissipate some of the generated heat into the ambient atmosphere. Second, since the mounting device 26 is in thermal communication with the tank 11, most of the generated heat can be conducted through the mounting device 26 into the tank 11 to be reused by the water heater 10. In some constructions, greater than fifty percent of the generated heat could be captured and used by the water heater 10. This increases the heating efficiency of the water heater 10.
Various other features and advantages of the invention are set forth in the following claims.
