Fluid and gas supply system

Automatic temperature and humidity regulation – Mixing fluid of dissimilar temperature – Mixing valve with temperature motive means

Reexamination Certificate

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Details

C236S051000, C004S676000

Reexamination Certificate

active

06286764

ABSTRACT:

TECHNICAL FIELD
The present invention relates to methods and devices for automatically monitoring and adjusting flow rates, volumes and temperatures of fluids and gases within plumbing and other supply systems, particularly within residential and commercial supply systems.
BACKGROUND OF THE INVENTION
A desired feature for fluid and gas supply systems is to provide fluid and/or gas flows within the system, particularly at system outlets, that can be maintained at pre-determined temperatures, flow rates and/or total volumes. For example, in residential plumbing systems, it is desirable to deliver fluid at system outlets, for example at a shower head, sink outlet, or appliance intake, at a stable, user-defined temperature, flow rate, and/or volume. Similarly, in commercial plumbing systems, such as those found in laboratories, medical facilities, aquacultural facilities, nurseries, manufacturing facilities, restaurants, hotels, and the like, it is desirable to provide fluid flows within the plumbing system and/or at system outlets that are maintained at a pre-selected temperature, flow rate, and/or volume.
Conventional supply systems that rely on manual valve mechanisms to adjust fluid flow rates and temperatures generally suffer undesirable fluctuations in temperature and flow values due to changes in demand/supply within the system. Initial fluctuations are attributable in large part to inadequate control devices, for example input and valve regulatory mechanisms. In this context, standard residential plumbing systems generally exhibit initial fluctuations of temperature and flow at system outlets due to insensitivity and/or overadjustment of user operated valves (eg., outlet controls for hot and cold water delivery). Moreover, even after desired temperature and flow values have been initially set by the user, swings in temperature and flow may continue to arise during use as a function of supply changes (eg., depletion of hot water) and remote demands (eg., initiation or cessation of demand by a second user) within the water system are a familiar occurrence. Thus, in the past it has been necessary to frequently manipulate system input controls and to tolerate reflexive changes and attendant delays for system equilibration in order to set and maintain desired temperature and flow values.
Despite the long persistence of these problems, current input and mixing systems for controlling fluid and gas temperature and flow rates fail to provide a full range of adequate solutions. For example, in most residential and commercial plumbing systems, devices and methods for controlling fluid temperature and flow at outlets still involve conventional hot and cold water valves. These are manually adjusted to independently regulate flow from the hot and cold water lines through the output. However, the tasks of manually initiating two valves or, optionally, a single valve with two inputs and one output, to select a desired flow rate and temperature, manually testing initial flow and temperature, and fine-tuning the valves to maintain desired flow and temperature, is time consuming and can expose the user to extreme, even dangerous, temperatures and flows. These problems are particularly notable in fluid supply systems having more than one outlet, such as in residential supply systems, were remote fluid demands by appliances or other users contribute to the frequency and range of temperature and flow fluctuations.
More advanced input and mixing devices for fluid and gas supply systems incorporate electronic input and control mechanisms to regulate fluid or gas temperature and flow. In this context, a variety of designs have been proposed for electronic-controlled mixing of hot and cold fluids to produce a mixed fluid having a preselected temperature. Many of those proposed systems utilize analog circuitry to provide a feedback control algorithm. For example, U.S. Pat. No. 4,359,186 issued to Kiendel discloses a mixing valve arrangement employing motor driven valves to supply hot and cold water to a mixing chamber. Temperature of the water in the mixing chamber is measured and is used, along with the flow rate of fluid moving through the mixing chamber, in an analog control circuit that provides signals to control the valve motors in response to temperature variations. However, this type of temperature control system is relatively inflexible, and, in order to adjust control constants or change the control algorithm, circuit components must be physically replaced or adjusted.
Other proposed fluid and gas control systems incorporate a digital processor, such as a microcomputer, for implementing a control algorithm. For example, U.S. Pat. No. 4,420,811 issued to Tarnay et al. discloses a water temperature control system in which a feedback control algorithm is implemented by a microcomputer. However, the valve arrangement, configuration of the water discharge channel, and the temperature sensor device of this system are not specifically directed to achieving rapid and accurate temperature and flow responses.
A more advanced fluid temperature control system is disclosed in U.S. Pat. No. 5,050,062 issued to Hass. This system uses a microcomputer coupled with a temperature sensor to provide automatic control of hot and cold supply valves, whereby a fluid mixture discharged from the system can be maintained at a preselected temperature within pre-determined limits. The fluid temperature control system actively mixes hot and cold fluids using together before measuring the temperature of the fluid mixture. Mixing of the fluids takes place in a special mixing chamber and is controlled for each of the hot and cold valves by a separate stepper motor connected therewith. The stepper motors move the respective valve members to regulate hot and cold fluid flow into the mixing chamber.
To control fluid mixing within this system, a temperature sensor is connected to the system outlet connection and is adapted to generates an analog signal corresponding to an actual temperature of the mixed fluid in the outlet connection. The analog temperature signal is amplified and conditioned, and thereafter converted into a digital temperature signal corresponding to the actual temperature of the mixed fluid. The digitized signal from the converter is sent to the microprocessor which is programmed to use the digitized temperature signal within a feedback control algorithm to generate control signals for the stepper motors to regulate the hot and cold supply valves to cause the actual temperature of the mixed fluid to approach the preselected temperature. In more detailed embodiments, the system allows for entry of a selected set point temperature by a user inputting the selection into a programmable microprocessor, for example by means of a keypad or remote computer connected to the processor. Also provided is a display for indicating system parameters, including the set point and actual temperatures of mixed fluid, and a selected flow rate.
Other proposed fluid control systems also incorporate a microcomputer for automatically adjusting fluid system parameters. In this regard, U.S. Pat. No. 5,170,361 issued to Reed et al. discloses a similar control system to that set forth in the Haas patent, supra. However, system parameters which are monitored and maintained to closely approximate user selections via the microprocessor include temperature, flow rate, and volume. This system also features first and second valves to regulate fluid flow from two supplies (eg., hot and cold), along with sensing means to sense open or closed positions for each valve. Also provided are means for activating the first and second valves to regulate their discharge into a dispensing pipe. Other sensors include mixed flow and temperature sensors.
The system of Reed also features a user input that provides for termination of hot and/or cold fluid flow, and for selection of mixed fluid flow rate and temperature. A processor receives data from the sensors (valve, temperature, and flow) and provides a signal to control the valve activating means, to

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