Fluid handling – Self-proportioning or correlating systems – Self-proportioning flow systems
Reexamination Certificate
2000-03-03
2001-07-24
Hepperle, Stephen M. (Department: 3753)
Fluid handling
Self-proportioning or correlating systems
Self-proportioning flow systems
Reexamination Certificate
active
06263899
ABSTRACT:
This invention relates to improvements in non-scald mixing valves for shower and bath installations.
BACKGROUND OF THE INVENTION
Many variations on mixing valves for showers and baths have been developed and marketed. These include thermostatically controlled valves and pressure balanced valves. Typically a sensing-controlling element, such as a thermostatic expansion device or a pressure sensing-and-balancing piston senses a change in flow conditions and automatically opens or closes orifices to compensate for the change. To be effective the sensing-controlling element must “see” and act upon the incoming water flow upstream of any temperature setting element or mechanism.
Mixing valves of the type comprising a water pressure-sensing- and-balancing piston are exemplified by those disclosed in U.S. Pat. Nos. 2,308,127; 3,099,996; and 3,448,755. In such valves the hot and cold water sources are applied to opposite ends of the piston, and as pressure variations take place the piston is caused to move under the action of the pressure difference that occurs. The water flows through orifices controlled by the piston to another orifice pair that are set to proportion the hot/cold flow mix.
Since the sensing element, i.e., the water-pressure equalizing piston, must “see” and act upon the source water supply pressure, it must be connected directly across the hot and cold water supplies. Accordingly, if a leak occurs, hot water could be introduced into the cold water supply and vice-versa. To prevent that occurrence it is necessary to have a positive shut-off located up-stream of the sensing element. In mixing valves of the type described in the above-identified U.S. Patents, which type is more recently exemplified by the Temptrol® valves produced by Symmons Industries, Inc. of Braintree, Mass., this is accomplished by including two elastomeric “seats” that positively shut off the hot/cold supplies up-stream of the pressure balancing element. These seats are incorporated directly on the temperature setting, hot/cold ratioing element (the spindle assembly), obviating the need for separate check-valves as in many competing devices.
Also prior to the present invention it was recognized that use of ceramic members as valving elements in hot and cold water mixing valves offers several advantages, and a number of different water flow control products using ceramic components have been marketed. For example, kitchen and lavatory faucets using ceramic valving components have been developed and/or marketed by a number of companies, including Masco Corporation. See also U.S. Pat. No. 3,788,354, issued Jan. 29,1974 to Paul C. Symmons for Single Handle Water Mixing Valve. The use of ceramic valving elements in shower valves of the type having water pressure balancing piston elements is disclosed by U.S. Pat. No. 3,921,659 issued Nov. 25, 1975 to Charles J. Rudewick III for Modular Balanced Pressure Mixing Valve With Ceramic Valve Elements. Additionally Zurn Industries of Dallas, Tex. has marketed a shower valve using ceramic elements. However, to Applicant's knowledge, in the Zurn Company shower valve the ceramic elements are arranged so as to provide temperature-ratioing and shut-off control downstream of the pressure balancing element and, therefore, auxiliary check valves must be incorporated between the shower valve and the hot and cold water supplies to prevent backflow into the hot and cold water supply lines.
Non-scald shower and bath mixing valves using water pressure sensing-and-equalizing piston elements, notably valves having operating modes similar to those disclosed in said U.S. Pat. Nos. 2,308,127; 3,099,996; and 3,448,755, have achieved extensive commercial success because they have effectively eliminated the danger of accidental scalding resulting from a rapid change in water temperature as a consequence of a variation in water pressure, and also because their elastomeric seats positively shut off the hot and cold water supplies up-stream of the water pressure sensing and balancing means.
Nevertheless it has been recognized that there is a need to improve upon existing designs of non-scald mixing valves in a way that lowers manufacturing costs without any loss of non-scald protection and without requiring the use of check valves in the hot and cold water supply lines.
OBJECTS AND SUMMARY OF THE INVENTION
The primary object of this invention is to provide a new and improved pressure-balancing non-scald mixing valve that offers the advantages of lower manufacturing costs, uses virtually indestructible ceramic valving elements, and avoids the need for check valves to prevent backflow into the hot and cold supply lines.
Another important object of this invention is to provide a new and improved pressure-balancing non-scald mixing valve that is characterized by the use of ceramic elements to provide both the shut-off function and the temperature-ratioing function.
A further object is to provide a new and improved non-scald mixing valve of the type having a water pressure-equalizing piston for automatically opening and closing orifices to compensate for changes in cold or hot water pressure, characterized by the use of ceramic elements as means for accomplishing the shut-off function and means for accomplishing the temperature-ratioing function, while allowing the piston to be connected directly across the hot and cold water supplies.
The foregoing and other objects hereinafter rendered obvious are accomplished by utilizing a sliding ceramic face valve pair to provide both the required shut-off function and the temperature-ratioing function, with one ceramic element constituting a stator and the other a slider.
More specifically the new and improved mixing valve design comprises a valve body having cold and hot water supply ports, at least one mixed water outlet port and an opening for accommodating a mixing chamber member and a spindle assembly that extends into the mixing chamber assembly. The mixing chamber member is hollow and defines a mixing chamber having cold water inlet and transfer ports and hot water inlet and transfer ports, with its cold and hot water inlet ports communicating with the cold and hot water supply ports. Disposed in the mixing chamber is a ceramic stator having hot and cold water inlet orifices that communicate with the mixing chamber's cold and hot water inlet ports and cold and hot water outlet orifices that communicate with the mixing chamber's cold and hot water transfer ports. The spindle assembly comprises (1) a balancing piston block disposed within and movable bidirectionally lengthwise of the mixing chamber member, and (2) and a ceramic slider engaged with and movable with the balancing piston block. The balancing piston block has an internal chamber and four side orifices that open into said internal chamber. The slider has a cold water inlet orifice, a cold water exit orifice, a hot water inlet orifice, and a hot water exit orifice aligned with first, second, third and fourth ones respectively of the four side orifices of the piston block. The spindle assembly also includes a pressure- balancing piston disposed within and slidable bidirectionally along the balancing piston block's internal chamber, the piston having a cold and hot water side inlet ports and cold and hot water end outlet ports. The cold and hot water outlet ports of said piston are in constant communication with the cold and hot water transfer ports of said mixing chamber, while the piston's cold and hot water inlet ports move through varying degrees of alignment with the cold and hot water inlet ports respectively of the mixing chamber as the piston moves back and forth. The degree that the cold and hot water inlet ports of the piston are aligned with the cold and hot water inlet ports respectively of the mixing chamber is a function of the pressures of the hot and cold water supplied to the mixing chamber's cold and hot water inlet ports.
The spindle assembly further includes an actuating member in the form of a lead screw that is coupled to the balanc
Hepperle Stephen M.
Pandiscio & Pandiscio
Symmons Industries, Inc.
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