Fluid handling – Convertible
Reexamination Certificate
1999-08-05
2001-09-25
Buiz, Michael Powell (Department: 3753)
Fluid handling
Convertible
C137S625170, C137S625410
Reexamination Certificate
active
06293299
ABSTRACT:
FIELD OF USE
The invention relates to a single-handle mixing valve, and more particularly, a limiting device for use with the single-handle mixing valve for controlling the maximum flow-volume and/or the maximum temperature of water flowing through the valve.
BACKGROUND OF THE INVENTION
Single-handle mixing valves have become commonplace. However, many compromises have been built into mixing valves to accommodate high flow-volumes and easy temperature control. Also, while limiting devices have been used, they are generally complicated mechanisms that cannot be easily repaired or replaced.
Since water ignition systems control many home water heaters, water is quickly heated to the selected temperature when the water outlet is opened. A normal home water heater can heat water to more than 150° F., whereas optimum water temperature for washing and bathing is maintained between 95° F. and 104° F. Scalding occurs at about 115° F. Accordingly, it is practical to limit the maximum water temperature. Also, with the changes of seasons and changes in settings of the water heater, the water temperature being dispensed varies.
Anti-scald configurations are known for shower handles where a single handle controls the full range of water temperatures. The handle generally moves through a wide range of motion so that the person taking the shower can make minor adjustments without risking being exposed to severe temperature changes. By limiting the range of motion of these handles, scalding temperatures are avoided. Similarly, in single-handle modular cartridge valves, an insert interposed between the operating stem and the temperature control knob orientates the knob with respect to the valve housing.
The single-handle mixing valve generally has a control stem extending out from the valve housing and connectable to a control stem to control the position of the valve. The range of motion of flow-volume and water temperature is defined by the shape of the opening in the guide template. The internal position of the volume and temperature limiting devices renders them difficult to change. In addition, repair or replacement of the limit structures requires that the main water line be shut off from the valve.
The primary problem still remaining is to adjust the maximum water output and to suitably limit the temperature of the mixed water when the valve is fully opened. Such a possibility appears desirable for a more efficient use of mixing valves by preventing an unnecessary waste of water and, in particular, of hot water in order to prevent scalding and to achieve a substantial saving of energy.
What is needed is a single-handle mixing valve having a valve housing that prevents excessively high water temperatures and flow-volumes; that includes means for retaining interchangeable cams as part of the valve housing, each cam either having or not having maximum flow-volume and temperature stops enabling the ready replacement of the cam without the need to disassemble the valve housing, that is simple in structure, durable in use, and economical to make.
What is needed is an easily assembled limiting device for use with a single-handle mixing valve which provides full adjustment of the flow-volume and temperature in a cartridge-type configuration that can be readily adjusted for varying maximum flow-volume and/or maximum temperature; that can be applied to the exterior of the valve housing; that has valve mechanisms housed in a cartridge that can be easily replaced when necessary; and that is independent of the guide mechanism to enable easy replacement of limiting elements for changing the maximum flow-volume and temperature profile of the mixing valve without disassembly of the valve housing.
What is needed is a limiting device for an improved single-lever flow-control valve which has a long service life and that can be varied in the field either during installation or servicing without any special tools simply be either adding an insert to a guide template or by replacing an insert with another insert having a different controlling edge.
SUMMARY
It is the primary objective of the present invention to provide a device that can be easily changed without disassembly of the valve housing that will enable (1) conventional maximum water temperature and conventional maximum flow-volume of water; (2) limited maximum temperature and conventional maximum flow-volume of water; (3) conventional maximum water temperature and limited maximum flow-volume of water; and (4) limited maximum water temperature and limited maximum flow-volume of water, the limits being readily adjustable and easily changed either installation or during servicing, with no special tools.
It is another objective to provide a simple and economical means to limit the repositioning of the control stem in a first direction to limit maximum water temperature, in a second direction to limit maximum flow-volume, and in a combination of the two directions to limit both maximum water temperature and maximum flow-volume of the mixed water.
These problems and objectives are addressed by the limiting device of the present invention. While one skilled in the art will readily understand that the principles of the present invention are applicable to a wide range of single-handle mixing valves, including flat plate valves, for purposes of illustration reference is made hereinafter to a ball valve.
A conventional ball-type single-handle mixing valve includes a valve body having a pair of inlet ports for hot and cold water, respectively, in fluid communication to an outlet port. A control stem extends outwardly from the valve body and is connected to the valve member for unitary movement with the valve member. The ball valve is pivotably mounted in a valve housing. The housing has a plurality of ports in fluid communication with the cavity and the ball valve has a plurality of openings in an outer spherical valve surface. The openings cooperate with the ports to control water flow through the ports. When the control stem is raised, the output port of the mixing valve is opened. The inlet ports become aligned with at least one of the openings. When the control stem abuts the forward edge of the camming aperture, the inlet ports in the housing and the openings in the ball element are aligned to allow maximum flow.
The limiting device of the present invention is for use with the single-handle mixing valve for limiting the maximum water flow-volume or the maximum water temperature through the valve. The device that limits the range of motion of the control stem of a single-handle mixing valve, and comprises a guide template and an insert.
The guide template generally defines the range of motion of the control stem, the control stem being positioned within the camming aperture. The position of the control stem determines the flow-volume and temperature of water flowing into the outlet port. The control stem extends from the valve chamber through a camming aperture in the guide template. The camming aperture has a shape that is generally the same as the range of motion of the control stem, such that the shape of the camming aperture defines the maximum flow-volume and temperature of the valve. The camming aperture design is configured to limit the range of motion of the control stem and prevent scalding water and excessive flow-volumes from passing through the outlet port. The guide template includes a guide-cover key that prevents any rotary movement of the guide template relative to the single-handle mixing valve, and a guide-insert key.
The insert further limits the range of motion of the control stem during engagement of the insert with the guide template. The insert includes an insert-limiting edge, that reduces the size of the camming aperture during engagement of the insert with the guide template. The insert also includes an insert-cam key that operates in conjunction with the guide-insert key to retain the insert relative to the guide template during engagement of the insert and the guide template.
For a more complete understanding of the limiting devi
Buiz Michael Powell
Doigan Lloyd D.
Kapustij Myron B.
Krishnamurthy Ramesh
Masco Corporation of Indiana
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