MXPA96000143A - Automatic faucet with temperature sensor - Google Patents

Abstract

A system for automatic temperature regulation for a tap, especially an automatic tap in which the flow of water is activated by means of a switch that does not require touch, is built to operate in a way that compensates for the waiting time of the hot water It comes from the hot water supply. The apparatus includes at least one temperature sensor, this first sensor is disposed in the hot water supply line upstream of the hot water valve. A more sophisticated apparatus includes a second temperature sensor arranged to detect the temperature of the outlet water. The methods for automatically regulating the temperature of the outlet water from an output activated remotely or activated by means of a switch that does not require touch to compensate for the expected arrival of hot water from the hot water source, are also described.

Description

* AUTOMATIC FAUCET WITH TEMPERATURE SENSOR " INVENTOR AND OWNER: K. GENE HANSEN.

NATIONALITY: NORTH AMERICAN CITIZEN.

RESIDENCE: 8935 KINGS HILL DRIVE SALT LAKE CITY, UTAH 84121 E.U.A.

BACKGROUND OF THE INVENTION FIELD OF THE INVENTION This invention relates to automatic taps and particularly to the improved temperature control of the water flow of such taps. STATE OF ART Automatic taps, in which the flow of water starts and stops according to the presence of a user's hands near the tap, are known. Examples of these include the following U.S. Patents: Nos. 5,074,520, 5,062,164, and 4,886,207 to Lee et al., No. 5,309,940 to Delabie et al., No. 4,682 to Hill, No. 5,095,941 to Betz, No. 4,928,732 to Hu, No. 5,050,641 to Shwu-Fen, No. 4,688,277 to Kakinoki et al, No. 4,767,922 to Stauffer, No. 3,480,787 to Johansen, and No. 3,576,277 to BlacJanon. Additionally, the publications of the United Kingdom Patents Nos. 2226 105 A by Wu, 2 226 104 A by Wu, and 2 255 625 A by Bosch, and European Patent Publication No. 0 387 471 A "by Nilsson and Maattanen also reveal automatic taps, however, most of the automatic taps of the prior art have disadvantages.In some cases, the installation of the faucet requires the construction of additional plumbing and / or electrical lines, therefore the replacement of the taps is made. Conventional faucets are expensive and tedious.In other cases, the temperature of the tap water is not regulated satisfactorily.First, the water that is housed in a hot water line before the tap is turned on, will typically be a cooler temperature than the hot water supply, therefore, if the desired water outlet temperature is warm or hot, a higher flow rate is needed from the hot water valve to produce Go a water outlet of the desired temperature when the tap is opened for the first time. In a conventional tap operated manually, the user compensates for this by first opening the hot water to the maximum, and then, as the temperature of the hot water rises, reduce the flow of hot water and open the cold water valve. However, in a tap which is activated by means of a switch that does not require touch, the user can not, or does not wish, to manually adjust the flows of hot and cold water. In many automatic taps, the relative flows of hot water and cold water are fixed throughout the activation period. That is, when the tap is turned on, the hot water and cold water valves open to their respective positions calculated to provide water at the fixed temperature assuming that the hot water is at the hot water supply temperature.

Therefore, the water that flows initially through the outlet is usually colder than the fixed temperature. Especially in winter, or if the pipes are close to air conditioning or refrigeration units, this temperature can be uncomfortably cold. If the period of use is short, the water in the outlet can never reach the fixed temperature. If the user tries to wait for warmer water to arrive, water is wasted, since in many areas of the country water conservation is a high priority. Or, if the user moves their hands away from the tap area while waiting for warmer water to arrive, the water flow can be interrupted by the automatic sensor. In addition, most such taps only have temperature sensors in the downstream mixing area of both the cold water inlet and the hot water inlet. Such a sensor will detect a cool or cold temperature when the water flow is activated, and typically the tap will respond by increasing the proportion of hot water entering the mixing area. This can result in an overproportion in the temperature of the water that comes out of the tap, at a temperature that is painfully hot and even scalding. Again in response only to the temperature of the mixing area, the tap can overcompensate by cooling, supplying water which is colder than the fixed or desired temperature. Therefore, the temperature of the water at the outlet of the tap can fluctuate initially between too hot and too cold, before finally achieving the fixed outlet temperature. Accordingly, there remains a need for an automatic tap apparatus which delivers water at a uniform pre-set temperature throughout the activation period, without large sub- or overheating and which follows changes in water temperature in the line of hot water immediately upstream of the mixing area. There also remains a need for a temperature regulation system for an automatic faucet, which compensates for the waiting time for the arrival of hot water. Desirably, the automatic faucet apparatus and the temperature regulation system should be easily replaced in a conventional faucet. SUMMARY The invention comprises an automatic temperature regulation system for a faucet in which the water flow is activated by means of a switch that does not require touch, and an automatic faucet apparatus that includes the automatic temperature regulation capability. The invention also provides a method for automatically regulating the temperature of the outlet water from an output activated remotely or activated by means of a switch that does not require touch, which compensates for the waiting time of arrival of hot water from the supply of hot water. In a preferred embodiment, the automatic temperature regulation system provides for the selection of the pre-set temperature of the outlet water by a user. A basic automatic faucet system includes a hot water line, a cold water line, a mixing region to which hot water and cold water lines are connected, and a faucet or outlet connected downstream of the region of mixed, which provides a flow of water to a user's location such as a sink. A hot water valve controls the flow of hot water into the mixing region, and a cold water valve similarly controls the flow of cold water. A switch sensor that does not require touch is located so that it detects an object such as a user's hands at a command location. The command location will typically be found, but not necessarily, close to or identical to the user's location. In the temperature regulating system of the invention, a first temperature sensor is located to detect the temperature of the water in the hot water line just upstream of the mixing region. A controller is connected to receive signals from the first temperature sensor and the switch that does not require touch, and to control the hot and cold water valves. The controller calculates the position of the hot water and cold water valves to achieve a pre-selected temperature, and activates the hot water and cold water valves to the appropriate positions. The controller is also constructed to determine the positions of the hot water and cold water valves according to whether the first temperature sensor is within an acceptable range of the hot water temperature of the source. If not, due to the cold water lodged in the pipe, the controller reduces or slows the flow of cold water until the first temperature reaches the expected hot water temperature. Optionally, but desirably, a second temperature sensor is placed to detect the temperature of the water in the mixing region. In this mode, the controller is also constructed to vary the respective flows of hot water and cold water to obtain the second temperature at the preset outlet temperature., using the temperature information provided by both temperature sensors. The controller is particularly constructed to compensate for the waiting time for hot water to arrive in the mixing zone from the hot water source. In a highly preferred embodiment of the faucet apparatus with automatic temperature regulation, including the hot water and cold water valves, the temperature sensors, the switch that does not require the touch and the controller, is constructed to be mounted in an installation of conventional tap without requiring additional water lines or any other electric line that is not of the standard type of 120 volts AC. BRIEF DESCRIPTION OF THE ILLUSTRATIONS In the illustrations, which show what is currently considered the best way to carry out the invention; FIG. 1 is a schematic diagram of a tap system of the invention; FIG. 2 is a flowchart of a mode of operation of the tap system of FIG. 1; FIG. 3 is a schematic diagram of an alternate mode of the tap system; FIG. 4 is a flow diagram of one embodiment of the operation of the apparatus of FIG. 3; and FIG. 5 is a flow diagram of an alternate embodiment of the operation of the apparatus of FIG. 1 DETAILED DESCRIPTION OF THE ILLUSTRATED MODALITY As can be seen in FIG. 1, a preferred embodiment of an automatic tap system with automatic temperature regulation capability includes an outlet or tap 100 connected to a hot water line 102 and a cold water line 104. The hot water line 102 and the cold water line 104 are connected in a "T" type junction 105 to an outlet segment 106, which ends in the tap 100. The junction 105 and the outlet segment 106 together constitute a mixing zone, in which the water flows from the cold water and hot water lines are combined before leaving by the tap. A hot water control valve 108 controls a flow of water from a hot water supply (not shown), and a cold water control valve 110 controls a flow of water from a cold water supply (also shown) . A touchless switch 112 is positioned for activation by a user whose hands are in the vicinity of the tap 100. A water temperature selector 114 is positioned near the user's or sink's location (not shown) within from which the water flows from the tap 100. A first temperature sensor 116 is arranged in the hot water line 102 upstream of the hot water control valve 108. A second temperature sensor 118 is arranged in the mixing zone. downstream of junction 105.

A controller 120 is connected in communication to receive and / or read signals from the switch that does not require touch 112, from temperature selector 114, and from both temperature sensors 116, 118. Controller 120 is also connected to control the hot water valve 108 and the cold water valve 110, and to receive electric power from a source of electrical energy, which is constituted by a conventional 120 volt AC outlet, modified with a transformer at 24 volts AC 124. The controller 120 is constructed to activate hot water valve 108 and cold water valve 110 in response to an "on" signal from the switch that does not require touch 112. Controller 120 is further constructed to regulate water temperature outlet by varying the respective amounts of water flowing through the hot water valve 108 and the cold water valve 110 of water. The values of the hot water temperature and the outlet water temperature read respectively by the hot water sensor 116 and the outlet water sensor 118 are respectively determined. The controller varies the relative flows from the hot water and hot water valves. cold water to compensate for the waiting time of the hot water that arrives from the supply of hot water.

The controller determines the initial values of hot water and cold water using the temperatures detected in the hot water line by means of sensor 116 and in the mixing zone by means of sensor 118. While the tap remains on and warmer water " exit "from the hot water supply, the temperature sensed by the sensor 116 increases, and the controller changes the positions of the valves to reduce the hot water flow rate. The temperature regulation process which the controller is constructed to follow also includes a feedback cycle type process based on the temperature detected by the sensor 118 near the outlet. The operation controller 120 is described in greater detail subsequently, with reference to the flow chart of FIG. 2. Desirably, the faucet apparatus further includes a water temperature monitor, which displays the temperature sensed by the sensor 118 near the faucet 100. The temperature monitor may be connected to the controller as shown in FIG. 1, or alternatively it may be directly connected to the sensor 118. By observing the reading of the temperature of the monitor, a user may wait until the water temperature reaches a comfortable level before introducing his hands. The hot water and cold water valves 108, 110 are variable flow valves constructed to provide selectable flow rates. In a working model of the FIG modality. 1, solenoid valve VA- (= 51 from Johnson Controls, 2255 South Technolo-gy Parkway, West Valley City, Utah 84119 is used. However, variations of the device using other types of valves such as continuous, cycle of work, or gradually controlled valves, are contemplated The switch that does not require touch 112 can be any switch that does not require the proper touch compatible with the tap environment, as is known in the art. do not require touch include active infrared switches, in which the user's hand reflects an in-infrared beam towards an infrared light detector; passive infrared switches, in which a user's hand blocks an infrared beam and prevents it from reaching a infrared detector, and the inductive triggers In a working model of the system of FIG 1, an invisible beam input alarm switch by Radio Shack (I nvisible Beam Entry Alert), catalog number # 49-311. Another suitable switch of Radius Shack is the Invisible Pulse Intrusion Sensor (Pulsed Infrared Invisible Beam Intrusion Sensor), catalog number # 49-551A. A switch that does not require touch which can be fixed directly to the outlet of the faucet is another useful choice. The controller can be any suitable logical "chip" that has the appropriate inputs and outputs to communicate with temperature sensors, valves, and the switch that does not require touch, and programmable to execute functions as describes The controller contains code that directs the execution of the temperature regulation physically contained within, as is known to those skilled in the art. In the current work mode, the controller is a DS5000 microcontroller integrated circuit available from Systronix, Ine, Salt Lake City, UT. However, other types of integrated circuits such as discrete logic integrated circuits, or specially designed integrated circuits, may be used. FIG. 2 describes the steps of a mode of a temperature regulation method or process which controller 120 is constructed to execute. The process is initiated by the controller upon receiving an "on" signal from the switch that does not require a touch indicating that the water flow must be activated (step 200). The controller then reads temperatures A and B from sensors 116 and 118, respectively, and also reads the fixed temperature point from water temperature selector 114 (steps 202 and 204). Steps 202 and 204 may be carried out in reverse order. Then, the controller determines the initial positions of the valves H and C, which respectively are the po- >; The water valve heats up and the cold water valve results in a mixed water outlet, having the desired fixed temperature point, based on temperatures A and B (step 206). The controller then sends the signal to the hot water and cold water valves so that they open to their initial valve positions (step 208). In step 210, the controller reads the temperatures A of the cold water and B of the outlet water. The controller then asks if B differs significantly from the fixed temperature (step 212); if the answer is "Yes", the controller proceeds to determine new positions of valves H and C using the new readings of A and B (step 214). Continuing with this branch, the controller then sends the signal to the hot water and cold water valves to operate in accordance with the new valve positions (step 216). Following step 216, the controller returns to step 210. Alternatively, if in step 212 the answer is "No", the controller asks whether the new value of A differs significantly from the immediately previous value of A (step 220). If the answer is "Yes", the controller proceeds to steps 214 and 216, determining new valve positions and adjusting hot water and cold water valves to these positions. The controller thus follows the cycle through the steps of checking the temperatures of the two sensors and of comparing the temperature B to the fixed point of temperature, until an "off" signal is received from the switch that does not require the touch that indicates that the water flow must be finished. The manner in which the firing of the "off" signal is achieved varies according to the type of switch that does not require touch to be used and the specific instructions contained in the microcontroller, as will be apparent to those skilled in the art. . In response to the "off" signal, the controller closes both hot water and cold water valves. Steps 206 and 214 for determining the positions of the valves can be carried out in different ways. For example, the positions can be determined from a two-dimensional look-up table which cross-links the hot water temperature (temperature A), the cold water temperature and the set temperature point (the desired exit temperature). ), with the positions for both cold water and hot water valves. It can be assumed that the temperature of the cold water is a value of "water at room temperature", a different value according to the local environment, such as 55 degrees Fahrenheit which is the normal temperature for the groundwater lines. 0 the initial temperature of the water that is housed in the mixing zone (temperature B0 detected by the sensor 118 while receiving the "on" signal) can be used as the cold water temperature. The search table can be constructed empirically, or by using an algorithm which takes into account the volumes of hot water and cold water for particular valve positions, as will become apparent to the skilled artisan. A search table constructed using an algorithm can also be refined by testing the system empirically. In a highly refined mode, there may be a third temperature sensor located in the cold water line, and the controller would be connected to read this third temperature sensor. An algorithm for this situation would use the temperature of the cold water in addition to the temperature of the hot water and the fixed point of temperature. A search table for such a modality would be a three-dimensional search table. Alternatively, the controller may be self-constructed to calculate the positions of the valves from the fixed point of temperature and the temperature of the hot water A using an appropriate algorithm. The algorithm can be refined for systems that have different volumes of water flow and empirical tests. The extension to the more sophisticated version that has the third temperature sensor in the cold water line would be a simple matter for the specialized craftsman. Nevertheless, currently the two sensor system is preferred, since it is cheaper and will produce adequate temperature regulation in most faucet systems. An alternative, cheaper mode replaces a proportioning or mixing valve 300 in combination with hot water or cold water binary valves (valves are operable only between a state "on" and an "off" state) for the temperature selector 114 and the variable flow hot and cold water valves 108, 110 (FIG 3). Also, this mode lacks a temperature monitor of the water outlet. In addition, the controller 306 of the embodiment of FIG. 3 is built in a somewhat different way. The proportion valve 300 is in a permanently open state, and the relative flows of hot and cold water are fixed at the time of installation to provide a satisfactory mixture based on the average temperatures of the water from the hot water supply (when the hot water is "up") and the water that comes from the cold water supply. For example, when both hot water and cold water are "up", a mixture of 50% hot water and 50% cold water can produce a water outlet that is comfortably warm. Since the ratio of hot to cold water is fixed, the controller compensates for the waiting time of the hot water coming from the hot water supply by opening only the binary hot water valve when any of the temperatures A or B is too low. Once the temperature A reaches the maximum water temperature from the hot water supply, or the temperature B reaches the fixed temperature for which the proportion valve is fixed, the controller opens the cold water valve 304, while holding open the binary hot water valve 302. In an alternate mode, the proportioning valve 300 can be eliminated and the controller 306 is then constructed to operate both cold water and hot water binary valves according to a duty cycle, the cycle of Work is calculated according to the temperatures A or B detected. Still another modality would replace a three-step control valve instead of the two binary valves. In another alternative embodiment, the water outlet sensor is eliminated, and the controller only compares the temperature A to the temperature of the hot water supply that is specified in the controller memory. In this mode, the exit temperature sensor 118 can be eliminated, or it can function as a security device. In the latter case, if the temperature B rises above the preset temperature, as can occur if there is a fault in the flow of cold water, the controller would shut off the flow of hot water to prevent the user from scaling. A simplified modeling controller which controls the valves only according to temperature A can operate according to the flow chart of FIG. 4. As can be seen in FIG. 4, when an "on" signal coming from the switch that does not require touch is received in the controller (step 400) the controller first reads the temperature of the hot water line sensor 116, that is, the temperature A (step 402), and asks whether the temperature A is more than X degrees Fah-renheit below the temperature Y of the hot water supply specified in the controller memory (step 404). If the answer is "yes", the controller opens only the hot water valve (step 406). The controller then reads temperature A again and asks if the temperature A is more than X degrees below the temperature Y (step 410). If the answer is "no", the controller opens the cold water valve (step 412). After step 412, the controller continues to keep both hot water and cold water binary valves open until a "shutdown" signal is received (step 414), after which both cold water and hot water valves are closed (416) If the answer in step 410 is "yes, the controller repeats steps 408 and 410 in sequence until the response in step 410 is" no. "If in step 404 the answer is" no ", the controller opens both hot water and cold water valves (step 420). The controller then proceeds to steps 414 and 416. An "off" signal may be a signal generated by the switch that does not require touch, or may be generated by a timer associated with the controller which begins to count a preset interval when an "on" signal is received from the switch that does not require touch. An "off" signal may comprise one of the following conditions: a) the infrared signal does not detect the presence of a user and b) the fixed temperature indicated point has been reached, or c) the predetermined time limit has been reached. In yet another embodiment, the controller is constructed to first open the hot water and cold water valves upon receiving an "on" signal, and then performs the temperature checking functions. Both the controller 120 and the controller 306 can be configured to execute the temperature control functions according to this method; FIG. 5 illustrates the method as would be executed by means of the controller 120 of the apparatus shown in FIG. 1. In this control path, the first step 502 that follows the reception of an "on" signal is to check the selected outlet temperature, and open the hot water and cold water valves to the base positions for the selected temperature (step 504). Next, the controller checks the hot water temperature A, and asks if it is more than 2 degrees below the hot water source temperature to get the temperature B (steps 506, 508). If the answer is "yes", the controller closes the cold water valve (step 510), and continues only with the hot water valve, opened in its initial position, by a preset interval of two minutes (step 512). The preset interval does not need to be two minutes. The hot water flow interval can only be based on the time usually required for hot water to reach sensor A from the hot water source, and in preferred embodiments it can be selectable by the user at the time of manufacture. or of the installation. For example, an interval as short as some milliseconds, or less. 0, the controller can be built to keep the cold water valve closed until the temperature B reaches the fixed temperature for the water outlet. After step 512, the controller again asks if the temperature a is more than 2 degrees below the expected temperature of the hot water source (step 514), and if "no", the controller opens the valve. of cold water to its initial position (step 516). The controller then reads the temperature B, and asks whether the temperature B is up to about two degrees of the fixed temperature (steps 518, 520). If so, the controller continues to operate in the initial positions until an "off" position is received. If the answer is "no", the controller carries out a sequence to calculate the new positions of the valves, adjusting the valves to the new positions, and rechecking the temperature B, until the temperature B reaches the fixed temperature. Desirably, there is a safety device either incorporated into the controller's programming, or as a separate external mechanism, which will cause all the water to close if the temperature B reaches a temperature of more than 5 degrees above of the fixed temperature, or a selected upper temperature limit, to prevent scalding incidents. Of course this same computer logic can be used to mix gases as well as liquids simply by using control values designed for use with gases by volume instead of liquids by temperature and modifying the sensors accordingly. For example, mixing nitrous oxide (N20) with oxygen (02) through the use of this system at a predetermined level can be effective in dentistry and surgery as well as it can be beneficial to prevent unnecessary death if the device is pre-set to never allow a centering of values of less than 20% oxygen to occur. The device may even be designed to occur within a container or tank which precisely mixed the oxygen and nitrous oxide at a pre-set level instead of the two separate tank systems containing pure nitrous oxide or pure oxygen which are used in the present. It will be apparent that numerous modifications can be made to the apparatus, to the construction of the controller, and to the method of temperature regulation without departing from the concepts contained in this application. The clauses by themselves define the scope of what the inventor considers to be his invention.

Claims (13)

1. NOVELTY OF THE INVENTION Having described the invention, it is considered as a novelty, and therefore the provisions of the following are claimed: CLAUSES 1. An automatic tap apparatus with temperature regulation comprising: a tap to carry water to the location of a user; a hot water supply line that has a hot water valve that controls the flow of hot water from it; a cold water supply line that has a cold water valve that controls the flow of cold water from it; a mixing region connected to both said hot water line and said cold water line upstream of said tap and downstream of said cold water valve and said hot water valve; an automatic sensor arranged to detect an object placed at a signal location, and constructed to produce a user presence signal that reflects the presence or absence of an object at the location of the signal; and a first temperature sensor located to detect the temperature of the hot water within said line of hot water upstream of said mixing area, and constructed to emit a first temperature signal that reflects this; and control means having an internal memory, said control means are connected to receive said presence signal from a user, to read said first temperature signal, and to control said hot water and cold water valves, in which said control means are constructed to activate the flow of water from said hot water and cold water valves in response to said presence signal of a user, and to control said hot water and cold water valves according to said first signal Of temperature.
2. 2. The faucet apparatus of Clause 1, which also includes a second temperature sensor located to detect the temperature of the water in said mixing region and constructed to output a second temperature signal that reflects this, and in the which said controller is further constructed to control said hot water and cold water valves according to said second temperature signal.
3. 3. The tap apparatus of Clause 2, wherein said hot water control valves and said cold water control valves are both configured as variable flow valves responsive to said control means to produce flow rates. respective hot and cold specified by said control means, and wherein said control means are further constructed to vary said respective specified flow rates of said hot water and cold water valves in accordance with the temperature detected in said line of hot water and the temperature detected in said mixing region to achieve a pre-set temperature in said mixing region.
4. 4. The tap apparatus of Clause 3, which further includes temperature setting means operatively connected to said controller and positioned for operation by a user to select a desired outlet temperature.
5. 5. The tap apparatus of Clause 4, wherein said temperature setting means includes a multi-position switch constructed for manual operation.
6. 6. The faucet apparatus of Clause 4, which further includes temperature monitoring means operatively connected to said second temperature sensor to display a temperature reflecting said second temperature signal.
7. 7. The tap apparatus of Clause 1, wherein said controller is constructed to provide a disproportionately higher flow from said hot water valve when said first temperature signal indicates a temperature below a supply temperature of hot water specified in said internal memory.
8. The tap apparatus of Clause 7, which also includes a downstream ratio valve of said hot water line and said cold water line upstream of said mixing zone, said proportioning valve provides a fixed flow rate of said hot water and said water cold
9. 9. In an automatic faucet appliance that includes a hot water valve installed in a hot water supply line, a cold water valve installed in a cold water supply line, a mixing zone that connects the water line hot water and the cold water line downstream of the hot water valve and the cold water valve, an outlet downstream of the mixing zone, and an automatic sensor connected to the hot water valve and the cold water valve , and built for activation without need of the touch of hot water and cold water valves to carry a water outlet through the outlet via the mixing zone, improved temperature regulation means to regulate the water temperature of output comprising: a first temperature sensor located in the hot water supply upstream of the hot water valve, and providing a first signal that refl axis the temperature detected inside: a controller connected to said first temperature sensor to receive a first signal from it, and to the hot water valve and the cold water valve to control the quantities of hot water and cold water flowing respectively from the hot water and cold water valves, said controller is built to: calculate the positions of the hot water and cold water valves to achieve a preselected water outlet temperature, open the water valves hot and cold water to the positions calculated in response to an "on" signal received from the switch that does not require touch, read said first signal and compare it with a hot water value that reflects an expected temperature of the water source hot, and, if said first signal is unacceptably below said hot water value, re-position the valve of cold water to provide a reduced cold water flow, and re-set the cold water flow to the calculated value when the temperature detected by the first temperature sensor reaches the temperature of the hot water expected.
10. 10. The improvement of Clause 9, which further includes a second temperature sensor located near the outlet to provide a second signal that reflects the outlet water temperature, and wherein said controller is also constructed to read said second signal and compare it to a fixed temperature value that reflects the preselected temperature, and, if said second signal is unacceptably below said pre-selected temperature, recalculate the positions of the hot water and cold water valves, and reposition the valves. hot water and cold water to the recalculated positions.
11. 11. A method for automatically regulating the temperature of the outlet water from a faucet appliance having a hot water line and a cold water line connected respectively to supply hot and cold water to a mixing zone which is upstream of an outlet, and a switch to activate the water outlet of the outlet, which comprises the steps of: providing a variable flow hot water valve and a hot water temperature sensor in the upstream hot water line of the mixing zone; provide a variable flow cold water valve and a cold water temperature sensor in the cold water line upstream of the mixing zone; receive a signal from the switch indicating that the water flow must be activated; read the hot water temperature sensor; calculate the respective positions for the cold water valve and the hot water valve to provide flows of hot water and cold water to the mixing zone to achieve a pre-set temperature of the outlet water; adjust the cold water valve and the hot water valve to their respective positions; read the hot water temperature sensor; keep the hot water and cold water valves in their respective positions until a signal is received from the switch indicating that the outflow of water stops; and close the cold water and hot water valves.
12. 12. The method of Clause 11, which also includes the steps of: providing an output water temperature sensor located between the mixing zone and the outlet; and, after said step of positioning the cold water and hot water valves, read the temperature detected by the outlet water sensor; compare the temperature of the outlet water with the pre-set temperature; and if the outlet water temperature differs significantly from the current temperature, take an updated reading of the hot water sensor temperature; calculate a new set of positions of the hot water and cold water valves respectively from the updated reading; reposition the hot water and cold water valves to the new set of positions; and repeating said five preceding steps in sequence until the switch is operated to deactivate the water flow.
13. 13. The method of Clause 12, in which the switch is a switch that does not require touch. IN WITNESS WHEREOVER, I have signed the above description and claims of novelty of the invention, as attorney of K. GENE HANSEN., In Mexico City, Republic of Mexico on January 3, 1996. p.p. erra, Jr.