Fluid handling – Line condition change responsive valves – Direct response valves
Patent
1994-02-03
1995-10-03
Nilson, Robert G.
Fluid handling
Line condition change responsive valves
Direct response valves
F16K 1502
Patent
active
054543983
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a throughflow valve having a valve seat and valve body, particularly a check valve or safety valve for mixer valve damping means, in which a limited flow of fluid through the valve is permitted even when the valve body lies against the valve seat.
According to another aspect, the invention also relates to a metal mould tool for manufacturing the valve seat or valve body of such a throughflow valve.
STATE OF THE ART
Throughflow valves, such as check valves, in which a desired, restricted flow of fluid is permitted through the valve with the aid of a V-shaped recess in the surface of the seat when the valve is closed are known to the art. One serious drawback with valve seats of this kind, however, is that contaminants or foreign bodies present in the fluid that passes through the valve are easily caught in the V-shaped recess, thereby preventing the desired minimum flow of fluid or "leakage" through the valve when the valve is closed. The contaminants become wedged in the recess and are liable to jeopardize effective long-term functioning of the valve.
Also known to the art are different types of valves having sintered or porous valve bodies or barrier elements, which permit a given flow of fluid through the valve when the valve is closed. Examples of such valves are found described in DE,A1,3.140,438 (Wittenstein) and JP,A,61-96274 (Sumitomo Electric). These valves, however, are expensive to manufacture and problems are encountered in accurately determining the minimum amount of fluid that shall flow through the valve, particularly since there is a risk that contaminants carried by the fluid will collect in the porous or elastic valve material when the valve has been in use for some time.
Other, related valves used for different purposes than the aforesaid valves are described, for instance, in U.S. Pat. No. 3,185,438 (Smirra), EP,A1, 0 401 607 (Burkert) and EP,A2,0 381 925 (Cummins Engine Company).
SE,B,8604612-5 (publication No. 455,124) (FM Mattsson) describes a single-lever type mixer valve provided with a damping arrangement which incorporates a throttle plate functioning as a throughpass valve of the kind intended here.
OBJECT OF THE INVENTION
The object of the present invention is to provide at low cost an improved throughflow valve which will avoid the drawbacks of the earlier known, similar valves and which can be used in different contexts.
SUMMARY OF THE INVENTION
These and other objects are fulfilled by an inventive throughflow valve of the aforedescribed kind and generally characterized in that the surface of the valve seat and/or the valve body is irregular or roughened so as to permit a limited flow of fluid to pass between the irregularities in the valve-seat surface and/or the valve body surface.
This valve feature enables a minimum flow of fluid through the valve to be ensured without blockaging of the valve, in distinction to the earlier known valves.
Although fluid-carried contaminants may fasten in the roughened or irregular surface, it has been found in practice that these contaminants will be dislodged and removed within a short period of time, the effect produced by contact of the valve body with the valve seat also contributing in this respect.
The contaminants thus have no tendency to become firmly wedged, as in the case of valve seats provided with V-shaped grooves.
In practice, at least the major part of the irregularities should have a size in the order of 20-100 .mu.m (microns).
The irregular or roughened surface can be produced in practice by subjecting the metal mould tool used to manufacture the valve seat and/or the valve body to a "sparking operation", wherein when manufacturing the mould tool a voltage is applied between the tool and an electrode, thereby generating an electric arc which "pits" the material. The parameters applied during the sparking operation are selected so that the tool surface will be pitted with irregularities of a given desired size, which in the subsequent injection moulding process
REFERENCES:
patent: 1151329 (1915-08-01), Audett
patent: 2672888 (1954-03-01), Shields
patent: 4030520 (1977-06-01), Sands
patent: 4431019 (1984-02-01), Kopp
FM Mattsson AB
Nilson Robert G.
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