Thermostatic mixing valve with sequential manual control

Automatic temperature and humidity regulation – Mixing fluid of dissimilar temperature – Fluid from only one supply is controlled

Reexamination Certificate

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Details

C137S625140

Reexamination Certificate

active

06341731

ABSTRACT:

TECHNICAL FIELD
This invention relates to a mixing valve for cold and hot water of the type including a thermostatic device and a manual control device acting upon the inlet ports that pass the cold and hot water to a mixing region.
BACKGROUND OF THE INVENTION
According to Italian Patent No. 1,107,182 by the same inventor, a thermostatic faucet includes a mixer with manual control that sets a mixing ratio between cold water and hot water and a thermostatic device that, depending on the actual temperature of the mixed water, controls a choke valve inserted on the hot water supply to the manual control mixer so as to modify the mixing ratio set in order to maintain within a certain range the temperature of the mixed water that is actually delivered.
According to Italian Patent No. 1,279.194, by the same inventor, a thermostatic faucet includes a mixer with manual control that sets a mixing ratio between cold water and hot water and a thermostatic device that, depending on the actual temperature of the mixed water, controls a choke valve inserted on the cold water supply to the manual-control mixer so as to modify the mixing ratio set in order to maintain, within a certain range, the temperature of the mixed water that is actually delivered.
Both of these devices incorporate a certain material separation between the manually controlled mixer valve and the thermostatic device that complicates its design and installation.
According to Italian Patent No. 1,2273,178, a thermostatic mixing device to which one can also operate as a faucet includes inlet ports for cold water and hot water, arranged at the sides of a central outlet pipe. A mixing chamber receives water from regulated hot and cold inlet passages and a thermostatically controlled distribution valve operates so as to control the opening and closing in opposite directions of the respective regulated inlet hot and cold passages so as to maintain, within a certain and adjustable range, the temperature of the discharged mixed water. This device can be provided with a volume flow control valve for manually and simultaneously changing the useful opening of both hot and cold inlet pipes. The volume flow valve controls only the flow volume but does not have any effect on the mixing action or relative proportional of flow of hot and cold water. This device presents a general and particularly advantageous structure, although it does entail the inconvenience that temperature regulation is rather poorly sensitive and gives rise to a temporary over regulation phenomena (of referred to as an “overshoot”). Temporary overshoot occurs when upon movement of the temperature adjustment mechanism to a position corresponding to a given temperature, one initially gets an effective temperature change of discharged water that is considerably more than the desired change. The desired temperature change is reached only after a period of time after the thermostatic device had a chance to compensate. The adjustment of the temperature, controlled by the thermostatic element, is achieved by manual control of the position of the thermostatic element and the distribution valve operably connected to it, which directly affects the opening of the respective hot and cold inlets.
SUMMARY OF THE INVENTION
In accordance with one aspect of this invention, a thermostatic mixing valve can be used alternatively as a thermostatic faucet or as a thermostatic device for feeding one or several apparatus, each of which is provided with its own faucet, or with one or several faucets installed downstream from the thermostatic device. The thermostatic mixing valve combines the advantages of the prior art devices without entailing the installation or thermostatic overshoot inconveniences. In particular, the invention is a compact structure that is easy to make and install and ensures a high degree of adjustment sensitivity. It further can provide a guarantee against the delivery of excessively hot water also in the presence of abnormalities in water supply and, when it is used as a thermostatic faucet, it incorporates a manually operated sequential type control valve mounted in series with the thermostatic valve.
Preferably, the thermostatic mixing valve comprises two inlet ports for cold water and hot water, a mixing chamber, passages between the inlet ports and the mixing chamber, a discharge port from the mixing chamber for mixed water, a thermostatic element arranged at least partly in the mixing chamber, and an annular distribution slide valve controlled by the thermostatic element. Both inlet ports and discharge port are in a central body radially inside the annular distribution slide valve. The annular distribution slide valve is arranged so as to restrict the passage between only one of the inlet ports and the mixing chamber. A flow and mixing adjustment valve with manual control of the sequential type is mounted to control the two inlet ports.
The adjustment of the temperature of discharged water is set manually by the action of the manually operable sequential type control valve for the flow and the mixing action without the manual action directly changing the position of the thermostatic element and the distribution slide valve so that one can systematically eliminate the phenomenon of temporary overshoot. Furthermore, the action of adjusting the distribution slide valve, controlled by the thermostatic element, always works in a counteracting direction from the direction of manual action thereby limiting its effect. The consequence of two counteracting activities is that one must make a longer movement of the manual control to achieve a desired change. The gradation of adjustment is elongated and the profile of change is flatter. The quickness and precision of thermostatic adjustment are then enhanced by the fact that the distribution slide valve works so as to effectively restrict or increase flow cross section of only one of the inlet ports so that the mixing takes place due to the addition or restriction of only one flow to the volume of the other flow rather than through inverse variation of the volumes of the two flows.
In cases where the valve is used as a faucet, the manual operable sequential valve also intercepts or shuts off the delivered volume, functions as a non-return valve, and adjusts flow rate within certain limits. But the manual sequential valve inserted in the water supply lines can also be used as a thermostatic adjustment device for a water supply flow going to one or several apparatuses, each of which is provided with its own shut off and volume regulation valve or with one or several faucets inserted in the waterlines downstream from the thermostatic valves. In these cases, the manual control valve for the thermostatic valve is adjusted only to determine the desired temperature and not to intercept a shut-off water flow or regulate it.
In cases where one must ensure an upper limit of the temperature of the discharge water, the distribution slide valve is so positioned as to regulate, by the action of the thermostatic element, the cross-sectional area of the passage through which hot water passes from the pertinent inlet port to the mixing chamber.
On the other hand, in cases where it is not necessary to limit the temperature of the discharge water (for example, because hot water supply is provided at a limited or non-hazardous temperature), the distribution slide valve can also be arranged so as to regulate, by the action of the thermostatic element, the cross-sectional area of the passage through which cold water passes from the pertinent inlet port to the mixing chamber.
Preferably, when the valve is intended to be used a thermostatic faucet the manually operable sequential valve includes a pair of valve plates, preferably made of hard material with openings therethrough. A first fixed plate and a second moveable plate are in sliding contact with each other. The openings in the plates are positioned to ensure in succession a shut-off or intercept position, a range of sequential opening positions of the pertinent passage for cold water whi

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