Check valve

A check valve with a housing having a valve seat, a valve closing member cooperating with the valve seat and an upstream dirt trapping filter, particularly for sanitary water fittings, wherein the dirt trapping filter and housing are of a unitary construction.

CROSS REFERENCE TO RELATED APPLICATIONS 
This application is a national phase of PCT/EP92/00539 filed 10 Mar. 1992 
and based, in turn, upon Austrian national application A 1354/91 filed 5 
Jul. 1991. 
The invention relates to a check valve with a housing having a valve seat, 
a valve closing member cooperating with the valve seat and an upstream 
dirt trapping filter, particularly for sanitary water fittings. 
BACKGROUND OF THE INVENTION 
There is a general need for devices preventing return flow, for instance 
under conditions of underpressure, in order to prevent the penetration of 
air into a supply line, or the return to the supply duct of a liquid which 
had already passed through. With regard to water supply applications, 
there is a large interest in preventing a return flow of water into the 
supply lines, since the water might then lose its drinking quality. 
In order to prevent such return flows it is known to use check valves whose 
movable valve closing members are subjected to spring action in the 
direction of a valve seat which is provided in the housing of the check 
valve. 
In order to protect the valve control elements against the incursion of for 
instance Teflon-hemp (packing) residues, chips or similar dirt particles, 
which could affect the operational safety of the valve, it has been long 
known to arrange dirt trapping filters in water fittings, upstream of the 
valve control elements, these filters being separate components to be 
manufactured and mounted separately, which is not only expensive from the 
point of view of manufacturing and assembly, but furthermore presents the 
danger, for instance when the dirt trapping filter has to be mounted 
again, especially during repairs, that it will be left out altogether, 
thereby after a certain time, leading to the failure of the check valve. 
OBJECT OF THE INVENTION 
It is the object of the invention to eliminate this drawback and to provide 
a check valve of the aforementioned kind, which can be manufactured at 
relatively low cost, can be easily mounted and especially maintain 
operational safety, even after being in operation for a long time. 
SUMMARY OF THE INVENTION 
This object is achieved by rigidly connecting the dirt trapping filter with 
the housing. 
Preferably the dirt trapping filter is made in one piece with the housing. 
Further it is advantageous when the dirt trapping filter has a conical 
configuration and a largest diameter which is smaller than the outer 
diameter of the housing.

SPECIFIC DESCRIPTION 
The check valve according to the invention, can be arranged in the supply 
duct of a sanitary mixing faucet, e.g. within the connection point between 
the "S"-connections and a flow control valve. 
As can be seen from the drawing, the housing 1 is made in one piece with 
the conically shaped dirt trapping filter 4. At the same time the housing 
forms also the valve seat 2, against which the valve closing member 3 is 
pressed under the action of spring 6 with the assistance of seal 5. 
As is also apparent from the drawing, the housing 1 has a groove 1a 
receiving another ring 1b and is of the same outer diameter as a 
cylindrical portion 1c of the housing extending away from the seat 2. The 
latter has an inner diameter which is the same as the diameter of a 
passage 1c between the filter 4 and the small diameter portion of the 
bevel forming the seat 2. The outer diameter of the filter 4, however, is 
less than the outer diameter of the housing 2.