Reversibly wireable evaporator coil freeze-over prevention device
Heating, Ventilating, and Air Conditioning (HVAC) and refrigeration systems have a thermostat to allow users to set a desired temperature for living and storage spaces. The output from the thermostat is a so-called “Call for Cool” signal (CfC) used to start the system compressor and begin the cooling process. A circuit which interrupts the CfC signal from a thermostat to the compressor without using specific input and output connections to define the CfC signal is disclosed. The circuitry monitors the temperature of the evaporator, and if the temperature dips too low, the compressor is disengaged until the measured temperature rises above a safe level.
The present invention relates to refrigeration and Heating, Ventilating and Air Conditioning (“HVAC”) control systems, and more particularly pertains to a simple to install device that prevents evaporator freeze-over and subsequent compressor failure. Hereinafter referred to as “NoIce.”
BACKGROUND OF THE INVENTIONA refrigeration system and the air conditioning part of a Heating, Ventilating, and Air Conditioning (“HVAC”) system serve two purposes: they both cool and de-humidify the air circulated through them. These functions have been well described in the prior art, U.S. Pat. No. 2,932,178, Armstrong, et. al. and the typical refrigerant loop is shown in
Several problems develop if the refrigerant level in the system drops below ideal, or the conditioned space is very humid. The low temperature derived from the vaporizing refrigerant creates a cold zone in the evaporator immediately past the metering device. Moisture deposited in this area freezes and blocks air flow through the frozen portion of the evaporator. Ice is a good insulator, so over time the cold zone extends further into the evaporator, which expands the frozen area. As detailed in U.S. Pat. No. 3,845,637, Shepherd, once a sufficient amount of the evaporator is coated in ice, the refrigerant no longer vaporizes and liquid refrigerant returning to the refrigerant compressor causes the compressor to fail.
System configurations to prevent compressor failure due to evaporator freeze-over are known in the prior art U.S. Pat. No. 2,688,850, White. These configurations are necessarily built into the refrigeration and HVAC systems at the time of manufacture and cannot be retrofit into existing installations. While these system configurations may have met their particular objectives and requirements, the prior art does not describe a reversibly wireable evaporator freeze-over prevention device that is simple to install.
In HVAC and refrigeration systems, standalone timer relays are integrated into the refrigerant compressor control line (the so-called “call for cool” (“CfC”) command line) to keep the compressor from restarting for a pre-set time if power is interrupted while the compressor is running. In the industry, these relays are called “pressure release timers”, and this time delay function is essential to keep a compressor from failing due to disturbances on the power line (thunderstorms, etc.) The schematic of the system with a pressure release timer is shown in
If evaporator ice buildup is a problem, the device most often used in the industry today to prevent ice buildup is a separate timer relay that periodically puts the system into a “defrost mode” to allow any ice that may have formed in the evaporator to melt, as described in U.S. Pat. No. 5,870,899, Byung-Joon Choi. This defrost timer is installed in the CfC line in series with the pressure release timer, and is typically attached when the system is first installed. It is meant to be installed by skilled workers because it is powered from the main system power and runs continuously. This relay may solve an ice buildup problem, but it offers the owner no warning that an ice buildup problem exists, and it is inefficient because the “defrost mode” is invoked whether there is ice present or not. The defrost timer added to the typical control system is shown in
As described earlier, an HVAC or refrigeration system uses a control wire to connect the thermostat to the compressor. The reversibly wireable evaporator freeze-over prevention device described herein, which is also referred to as the NoIce Control, may replace both the defrost timer and the pressure release timer, see
The invention will be better understood and objects other than those set forth will become apparent when consideration is given to the following descriptions. Such descriptions refer to these drawings wherein:
The color of the CfC wire is standardized throughout the HVAC and refrigeration industry, and is well known to installers. The present invention is installed in the control circuit between the thermostat and the compressor just as defrost timers are, using wires matching the color-code of the CfC control wire. The term “reversibly wireable” means that like color-coded wires may be connected in either of two possible configurations: one of the like color-coded wires is connected to the compressor and the other like color-coded wire is connected to the thermostat, or vice-versa; the wires are interchangeable. The device is designed to be installed by technicians either during or after the initial system installation, and is thus simple to install, a key objective. The NoIce Control requires power only when the CfC command is active, so eliminates the need for connection to the main power portion of the HVAC or refrigeration system, attaining another key objective. It is energy efficient because it monitors the temperature of the evaporator only when it is powered, and acts only when ice is detected. The NoIce Control may also alert the user if the evaporator has frozen over, achieving yet another key objective. The program in the NoIce Control, which is a part of the device, is shown in flowchart form in
In this respect, the reversibly wireable evaporator freeze-over prevention device, according to the present invention, substantially departs from the concepts and designs of the prior art. The general purpose of the present invention is to provide a new and improved evaporator freeze-over prevention device, which has all the advantages of the prior art and none of the disadvantages. It provides a device exclusively developed to prevent air conditioner and refrigeration evaporator freeze-over that is simple to install, is energy efficient, uses only CfC and common connections, and alerts the user to incipient compressor failure.
In describing this invention, the word “coupled” means that the article or structure referred to is joined, either directly or indirectly, to another article or structure. The term “electronically coupled” means that the devices which are electronically coupled form part of the described circuit. By way of example, an engine starter is electronically coupled to a car battery. Also, when used as a noun to describe a component, the words “connection” and “connector” are interchangeable, that being a physical element to which another item is coupled or attached.
Referring to
There is a controller provided to measure the necessary temperatures, provide timing functions for the pressure release and defrost mode, provide signals to alert the user to ice buildup, and to control the driver. This device is identified as block 20, “CONTROL” in
The temperature sensor interface has a connection to the controller, and connections for the temperature sensor. This is identified as block 30, “INTERFACE” in
There is a driver provided to operate the interrupter in the CfC line. This device is identified as block 40, the “DRIVER” in
The temperature sensor itself is identified as block 50, “TEMPERATURE SENSOR” in
There is an electrical interrupter provided to disconnect the signal between the thermostat CfC line and the compressor. This device is identified as block 60, the “INTERRUPTER” in
Thus there has been outlined broadly some of the more important features of the invention in order that the detailed description thereof that follows may be better understood and that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject matter of the claims attached.
The invention is not limited in its application to the details of construction or arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of descriptions and should not be regarded as limiting.
It is therefore an object of the present invention to provide a new and improved reversibly wireable evaporator freeze-over prevention device for the refrigeration and HVAC industries that has all of the advantages, and none of The disadvantages, of the prior art systems to prevent evaporator freeze-over and subsequent compressor failure.
It is another object of the present invention to provide a new and improved a reversibly wireable evaporator freeze-over prevention device for the refrigeration and HVAC industries that may be easily and efficiently manufactured and marketed.
It is a further object of the present invention to provide a new and improved reversibly wireable evaporator freeze-over prevention device for the refrigeration and HVAC industries that is of durable and reliable constructions.
Still another object of the present invention is to provide a new and improved reversibly wireable evaporator freeze-over prevention device for the refrigeration and HVAC industries that is simple to install.
Lastly, it is an object of the present invention to provide a new and improved reversibly wireable evaporator freeze-over prevention device for the refrigeration and HVAC industries that operates in an energy efficient manner.
Detailed Description of the Preferred EmbodimentThe present invention, a reversibly wireable evaporator freeze-over prevention device, or NoIce Control, is shown in block form in
Connected to the NoIce Control in
The electronic components comprising each of the blocks from
The RECTIFIER/REGULATOR (
Voltage regulators (U2, D4) are linear buck regulators. A switching regulator may also be used. D2 may be a steering diode, or built of biased transistors, biased field effect transistors (FET), metal oxide field effect transistors (MOSFET), transistors, and thyristors.
Capacitors (C1-C5) are commonly available types well known to one skilled in the art. They include tantalum, ceramic, and aluminum electrolytic types.
The CONTROL (
This embodiment of the NoIce Control uses a microcomputer from Cypress Semiconductor (CY8C21123) for U1 to monitor the temperature of the evaporator coil. Other similar microcomputers are available from Silicon Laboratories, Intel, On Semiconductor, Texas Instruments, Microchip Technology, Fairchild Semiconductor, and ST Microelectronics, among others. The microcontroller has a built-in signal converter with which to read the raw NTC voltage value, and enough memory and mathematical operators to allow it to convert that reading to an accurate temperature. The microcontroller also has the necessary processing capability to maintain an operations list (such as time-versus-temperature, run time, and other parameters), and decision-making instructions, to allow it to determine whether an operational fault necessitating interrupting the CfC command signal has occurred.
The INTERFACE (
The DRIVER (
The TEMPERATURE SENSOR (
The INTERRUPTER (
The ALERT (
The preferred embodiment of the NoIce Control is designed to be installed by relatively unskilled workers, using only wire colors as the indicators for proper connection. Unlike more invasive installations, this unit requires only three wires to install. From
The operational parameters of the unit (times and temperatures in
The conception upon which this disclosure is based may be utilized readily as a basis for designing other structures, methods and systems for carrying out the several purposes of the present invention by those skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention. Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention. The claims must be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.
Claims
1. A reversibly wireable evaporator freeze-over prevention device comprising, in combination:
- a. a rectifier and regulator which may use either of two like color coded wires as an input, the second like color coded wire as an output and a third wire as common;
- b. a driver electronically coupled to an interrupter wherein the interrupter may open the connection between the input and output;
- c. a controller which may time events and measure a sensor signal, which controller is electronically coupled to the driver, to an alert device, and to an interface an interface electronically coupled to a temperature sensor.
2. A reversibly wireable evaporator freeze-over prevention device as recited in claim 1 wherein the alert device is a visible alert.
3. A reversibly wireable evaporator freeze-over prevention device as recited in claim 1 wherein the alert device is an audible alert.
4. A reversibly wireable evaporator freeze-over prevention device as recited in claim 1 wherein the alert device is a connection to a network in which to send an alert message.
5. A reversibly wireable evaporator freeze-over prevention device as recited in claim 4 wherein the connection to a network in which to send an alert message is a wireless connection.
Type: Application
Filed: Mar 28, 2019
Publication Date: Oct 1, 2020
Inventors: Peter Bycroft (Clearwater, FL), John Kohls (Pinellas Park, FL)
Application Number: 16/368,034