Mixing valve for hot and cold water

A mixing valve includes a housing having two inlets for receiving cold water and hot water. A valve member is secured in the housing and includes a membrane that may be easily secured between two casings. A valve stem is slidably engaged in the casings and has a middle portion secured to the membrane. The valve stem has two valve elements for engaging with the valve seats of the casings and for blocking the hot water when the cold water is not supplied to the housing. One or more control valves may be exchangeably secured to the valve member.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a valve, and more particularly to a mixing 
valve for hot and cold water. 
2. Description of the Prior Art 
Two typical mixing valves for faucets are disclosed in U.S. Pat. No. 
5,445,181 to Kuhn et al. and U.S. Pat. No. 5,730,171 to Niakan. The 
faucets comprise an integral structure having another control valve 
received therein for controlling the actuation of the mixing valve. 
However, the control valve may not be replaced or changed with the other 
water control. 
The present invention has arisen to mitigate and/or obviate the 
afore-described disadvantages of the conventional valves. 
SUMMARY OF THE INVENTION 
The primary objective of the present invention is to provide a mixing valve 
for hot and cold water, in which the mixing valve includes a control valve 
that may be changed or replaced with the other control valve for allowing 
the valve to be easily manufactured and assembled. 
In accordance with one aspect of the invention, there is provided a mixing 
valve comprising a housing including two inlets for receiving water, a 
valve member secured in the housing, the valve member including two 
casings secured together, the casings each including an inlet for 
communicating with the inlets of the housing and each including a valve 
opening and a valve seat and each including an annular shoulder, a 
membrane including a peripheral bead engaged in the annular shoulders of 
the casings and secured in place by the casings, the membrane including an 
annular bulge for defining an annular recess and for increasing a 
resilience of the membrane, the membrane including a center hole, and a 
valve stem including two ends slidably engaged in the valve openings of 
the casings and including a middle portion engaged through the center hole 
of the membrane and secured to the membrane, the valve stem including two 
valve elements for engaging with the valve seats of the valve member. A 
first of the valve elements is caused to engage with a first of the valve 
seats for blocking the water from a first of the inlets of the housing 
when the water is not supplied to a second of the inlets of the housing. 
Further objectives and advantages of the present invention will become 
apparent from a careful reading of a detailed description provided 
hereinbelow, with appropriate reference to accompanying drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to the drawings, and initially to FIGS. 1-4, a mixing valve in 
accordance with the present invention comprises a housing 21 including two 
inlets 22 coupling to two inlet pipes 23 for allowing cold water and hot 
water to flow into the housing 21. A valve member 20 is engaged in the 
housing 21 and includes two inlets 40, 41 (FIGS. 2-5) communicating with 
the inlets 22 respectively, and includes two outlets 48 (FIGS. 1, 4, 5) 
for allowing cold water and hot water to flow out of the valve member 20 
and to flow into a mixing chamber of a control valve 11 for mixing the hot 
water and the cold water. 
The valve member 20 includes two casings 30, 31 each having one or more 
projections 42, 43 for engaging with the housing 21 and for allowing the 
casings 30, 31 to be solidly secured to the housing 21. The inlets 40, 41 
of the valve member 20 are formed in the casings 30, 31 respectively for 
communicating with the inlets 22 of the housing 21. The casings 30, 31 
each includes an annular shoulder 46, 47 for engaging with the peripheral 
portion of the membrane 33 (FIGS. 4, 5). As best shown in FIG. 4, the 
membrane 33 includes a peripheral bead 50 for forming as a sealing ring 
and for being engaged in the annular shoulders 46, 47 of the casings 30, 
31 and for allowing the membrane 33 to be clamped in place by the casings 
30, 31. The membrane 33 includes an annular bulge 51 for defining an 
annular recess and for increasing the resilience and flexibility of the 
membrane 33. The membrane 33 includes a center hole 55 (FIG. 3) for 
receiving a valve stem 32. 
The casings 30, 31 each includes a valve opening 462 for slidably receiving 
the valve stem 32 and each includes a valve seat 464. Two valve elements, 
such as sealing rings 44, 45 are engaged on the valve stem 32 and provided 
on the opposite sides of the membrane 33 for engaging with the valve seats 
464 and for blocking and opening the inlets 40, 41. The valve stem 32 
includes a disc 36 for engaging with the membrane 33. A washer 38 is 
engaged on and secured to the valve stem 32 and is engaged with the 
membrane 33 for solidly securing the valve stem 32 and the membrane 33 
together. The casing 30 includes a disc-shaped plate 301 formed on top 
thereof and having two punctures 34, 35 formed therein and communicating 
with the outlets 48 of the valve member 20. The other casing 31 includes a 
smaller size having the plate 301 of the casing 30 engaged on top thereof. 
In operation, as shown in FIG. 4, when cold water and hot water are both 
supplied into the housing 21 via the inlets 22, the membrane 33 is 
balanced such that the cold water and the hot water may flow out through 
the valve openings 462 and the outlets 48 respectively. However, as shown 
in FIG. 5, when cold water is cut or is not supplied into the housing 21 
via the inlet 41, the water pressure of the hot water from the inlet 40 
may force the valve stem 32 rightward. At this moment, the valve element 
44 may be forced to engage with the valve seat 464 of the casing 40 and to 
block the hot water such that the hot water may be prevented from flowing 
out through the outlet 48 and such that the mixing valve may prevent hot 
water from hurting the user. On the contrary, when hot water is cut off or 
is prevented from flowing into the housing 21 via the inlet 40, the water 
pressure of the cold water from the inlet 41 may force the valve element 
45 to engage with the other valve seat 464 in order to prevent the cold 
water from flowing out through the outlet 48. 
It is to be noted that the valve member 20 includes two separate casings 
30, 31 such that the valve stem 32 and the membrane 33 may be easily 
secured and assembled in the casings 30, 31. The mixing valve thus 
includes a greatly simplified configuration for allowing the mixing valve 
to be easily manufactured and assembled. As shown in FIG. 1, the valve 
member 20 or the plate 301 of the casing 30 of the valve member 20 
includes one or more orifices 52, 53 formed therein. The control valve 11 
includes one or more protrusions 54 extended downward therefrom and 
engaged into the orifices 52, 53 of the valve member 20 for securing the 
control valve 11 to the valve member 20. One of the control valves 11 is 
disclosed in the applicant's prior U.S. Pat. No. 5,749,393 to Yang which 
is taken as a reference for the present invention. 
Referring next to FIGS. 6 and 7, the so-called spring cartridge type 
control valve 60 (FIG. 6) or the ceramic cartridge type control valve 61 
(FIG. 7) may also each include one or more protrusions 62 for engaging 
with the orifices 52, 53 of the valve member 20 and for exchangeably 
secured to the valve member 20. 
Accordingly, the mixing valve in accordance with the present invention 
includes a greatly simplified mechanism for allowing the mixing valve to 
be easily manufactured and assembled and for preventing the user from 
being hurt by hot water inadvertently. The control valves for the mixing 
valve may be replaced or changed with each other easily. 
Although this invention has been described with a certain degree of 
particularity, it is to be understood that the present disclosure has been 
made by way of example only and that numerous changes in the detailed 
construction and the combination and arrangement of parts may be resorted 
to without departing from the spirit and scope of the invention as 
hereinafter claimed.