Bleaching and dyeing; fluid treatment and chemical modification – Fluid treatment – Manipulation of liquid
Reexamination Certificate
1999-12-08
2001-12-11
Coe, Philip (Department: 1746)
Bleaching and dyeing; fluid treatment and chemical modification
Fluid treatment
Manipulation of liquid
C068S012220, C068S207000, C134S018000, C134S0580DL, C236S012120
Reexamination Certificate
active
06327730
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to the art of washing machines, such as clothes washing or dish washing machines and, more particularly, to an automatic washing machine incorporating a system for controlling the temperature of washing liquid introduced into a tub or basket of the machine during an operating cycle.
2. Discussion of the Prior Art
Essentially every washing machine has some type of control to set the temperature of the fill water entering an associated washing machine tub. Typically, systems known in the art rely on controlling the amount of fill water supplied through hot and cold water valves to establish a desired temperature. More specifically the desired temperature in such a known system is established by opening one or both of the controlling hot and cold water valves. For instance, hot water would be supplied by opening the hot water valve and closing the cold water valve; warm water would be supplied with both valves open; and cold water would be supplied by opening the cold water valve while leaving the hot water valve closed. This basic type of system may not be considered satisfactory for many reasons, mainly due to the potential for varying temperatures and pressures of the incoming cold and hot water streams. Therefore, such a simple system can result in widely ranging temperatures of the fill water supplied to the washing tub between different washing operations.
Water temperature is an important factor in cleaning. For example, in a clothes washer, if the wash water temperature is too cold for a given operation, inadequate soil removal can result, while a wash temperature which is too hot can result in clothing damage, as well as a waste of energy. In fact, it has been noted that certain detergents work well within a relatively narrow temperature range such that fill water outside a desired temperature range can degrade the performance of a detergent.
In an attempt to address this problem, many proposals have been set forth. Mostly, these solutions involve providing complicated control systems to control the flow of fill water provided by the hot and cold water valves. Typically, these systems incorporate one or more temperature sensors which provide feedback signals used to more precisely control the water valves. However, these temperature sensors are both extremely costly and prone to failure such that these overall systems raise economic and reliability concerns.
For example, U.S. Pat. No. 4,528,709 proposes a washing machine temperature control system wherein the temperature and flow rate of hot and cold water inlets are separately sensed. The system calculates from this data the quantity of hot and cold water necessary to arrive at a desired overall temperature given a selected amount of water desired in the washing tub. Of course, such a system requires at least two thermistor type sensors and a flow meter or the equivalent in order to obtain the necessary data. As stated above, such sensors are both expensive and prone to failure.
U.S. Pat. No. 4,330,081 proposes a water temperature control system for a clothes washing machine that is designated to control a desired water temperature for use in the clothes washing tub. This system essentially obtains the desired temperature values by memorizing desired temperatures based on the type of clothes to be washed, such as cotton, wool, polyester, etc. Once again, in order to achieve the desired results, the temperature of the combined water flow must be sensed, such as through the use of a thermistor. In addition, in accordance with this patented arrangement, a multi-vibrator is coupled to input gates of a microprocessor. Once again, this solution suffers from the defect of employing thermistors which are both expensive and prone to failure, as well as a suspect multi-vibrator arrangement.
As a final example, U.S. Pat. No. 5,439,019 discloses a method and apparatus for filling a washing tub of an automatic clothes washer that is designed to actively regulate the temperature of the final volume of water present in the washing tub based on a preselected temperature inputted by an operator of the washing machine. Once again, this patent discloses the use of a thermistor to achieve the temperature control function. Specifically a thermistor is used to obtain a measurement which is representative of the water flowing through a mixing valve.
Based on the above, there exists a need in the art of automatic washing machines for an adjustable water control system which can accurately control the temperature of the fill water entering the washing tub while not requiring the use of expensive temperature sensors and their associated electronics.
SUMMARY OF THE INVENTION
A washing machine constructed in accordance with the present invention incorporates a system for controlling the temperature of washing liquid, most commonly water, supplied to a washing tub in an accurate and cost effective manner without the use of a built-in temperature sensor. This system provides for inputs from an operator of the desired temperature for the fill water, as well as the amount of fill water desired to be placed in the washing tub.
In accordance with the invention, the washing machine incorporates a fluid container or fill tub having an inlet for both hot and cold water. The hot water inlet includes a first valve to control the flow of water therethrough. Likewise, the cold water inlet also has an associated, second valve for controlling the amount of cold water which enters the fill tub. In one preferred embodiment of the invention, a control unit is provided to regulate the quantities of water supplied to the washing machine tub according to preset hot/cold water ratios. Preferably, there are actually five preset ratios, i.e., hot, hot/warm, warm, cold/warm and cold. More specifically, the hot ratio would be 100% hot water and no cold water, the hot/warm ratio would be 75% hot water and 25% cold water, the warm ratio would include a 50/50 mix of hot and cold water, the warm/cold ratio would include 25% hot water and 75% cold water, and finally the cold ratio would include 100% cold water. Provisions are made such that the ratios may be fine tuned by the operator, with the actual ratio of hot and cold water entering the washing tub being established based on the preference of the operator. In accordance with one embodiment, temperature vs. ratio information is made available to the operator in chart form to enable programming by the operator such that the hot and cold water valves are accordingly controlled. Once initial operator adjustments are made and stored, the operator would only have to select a desired washing operation which would be performed at the predefined temperature established by the preset ratio for that cycle.
In a second preferred embodiment of the invention, instead of having the user input desired ratios for the various amounts of hot and cold water supplied to the washing tub, the user would instead input the actual water temperature desired for a particular washing operation. The control system, in effect, incorporates a look-up table such that the controller would determine, based on the temperature inputted by the user, what ratios of hot and cold water should be set to establish the desired fill water temperature.
Additional objects, features and advantages of the present invention will become more readily apparent from the following detailed description of the preferred embodiments when taken in conjunction with the drawings wherein like reference numerals refer to corresponding parts in the several views.
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patent: 5032992 (1991-07-01), B
Coe Philip
G.Diederiks, Jr. Everett
Maytag Corporation
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