Shut-off valve for fluids

The invention relates to a shut-off valve comprising a valve housing (12), a valve piston with valve cone (22) arranged up-stream of an associated valve seat (20), and a piston holder (16) axially movable within the valve housing (14) by means of a spindle (58) and accommodating said valve piston. To prevent overtightening of the valve piston, the piston holder (16) is connected to the valve housing (14) in the manner of a slip clutch. In addition, the outlet port (146) of the shut-off valve can be closed by a non-return valve.

STATE OF THE ART 
The invention relates to a shut-off valve for fluids comprising a valve 
housing, a valve piston with valve cone arranged upstream of an associated 
valve seat, and a piston holder accommodating the valve piston and being 
axially adjustable in the valve housing by means of a spindle, with the 
axial motion of the spindle holder being converted to a radial motion when 
the valve piston reaches a stroke limit. 
A corresponding shut-off valve is disclosed in EP-B-0 073 855. By the 
arrangement of the valve cone in relation to the valve seat and the 
provision of a slip clutch preventing the valve from overtightening either 
in the opening or the closing position, a highly functional shut-off valve 
particularly for sanitation fittings is available. A corresponding valve 
can also be made of plastic, entailing considerable advantages over metal 
valves with regard to production and wear. 
OBJECT OF THE INVENTION 
The object of the present invention is to develop a shut-off valve of the 
type mentioned at the outset such that simple design measures preclude any 
"overtightening" of the valve, and also to ensure that simple assembly is 
possible of the elements making up the valve. It should also be avoided 
that foreign bodies can flow through the valve, with backflow through the 
valve being prevented in particular. Finally, the possibility should also 
be created to install the shut-off valve in fittings with non-standard 
dimensions. 
The object is substantially achieved by providing the piston holder with 
axial projections on the outer wall which slide axially in associated 
axial recesses in the inner wall of the valve housing or which are movable 
into respectively adjacent recesses when the stroke limit is reached in 
order to achieve the radial motion. The recesses provided on the outer 
wall of the piston holder are preferably of "yielding" design here, in 
order on the one hand to avoid unwelcome wear and tear without however 
straining the axial guideway, and on the other hand to ensure that the 
projections "jump" from recess to recess when the stroke limit is reached. 
The individual elements preferably comprise plastics such as polyacetates 
or polyamides, which have long service lives. As a result, the 
manufacturing costs of a valve in accordance with the invention can also 
be considerably reduced. There are also advantages as regards weight. In 
accordance with a further noteworthy embodiment of the invention, the 
piston holder is connected to the spindle or shaft by a retaining element 
which passes through a radial slot in the piston holder. 
A proposal that is separately protected is that the port connecting a 
fluid-carrying fitting to the valve be closable by an element which is 
arranged coaxially to the valve piston and is axially movable, and which 
constitutes a non-return valve. Here, the element configured as a 
non-return valve is preferably movable underneath the valve seat and along 
the valve piston to make a sealing contact with a sector of the housing 
which in its turn accommodates the valve seat on the opposite side. 
Also noteworthy is the separately inventive proposal for the valve cone to 
be mounted axially movable by a chamber of hollow cylinder type which in 
its turn abuts in sealing contact against a port provided inside the 
fitting. The advantage of this is that the valve seat itself does not have 
to extend in a tubular area of the fitting, which would involve a mutual 
adjustment of the dimensions. 
Finally, the invention is distinguished in particular by the fact that 
length differences of the valve housing can be compensated by screwing a 
stop element preferably of cap nut type directly or indirectly onto the 
valve housing, where the axial movement of the stop element caused by the 
screw motion can be converted to an exclusively radial motion preferably 
depending on the torque to be applied for screwing. A slip clutch is 
therefore provided to ensure that no uncontrolled forces can affect the 
valve housing. 
The claims contain further features which have separately inventive content 
per se and/or in combination.

DETAILED DESCRIPTION OF THE DRAWINGS 
In the following description of preferred embodiments of shut-off valves 
and details of the latter, identical elements are provided with the same 
numbers for the sake of clarity. 
FIG. 1 is a sectional view of a shut-off valve (10) installed in a 
sanitation fitting (12) such as a water tap, the individual components of 
which require no detailed explanation. The direction of flow with which a 
fluid passes through the fitting (12) and so the valve (10) is indicated 
by the arrows. 
The shut-off valve (10) comprises a valve housing (14) in which a piston 
holder (16) is accommodated which in its turn holds in its front portion a 
valve piston (18) with valve head (22). The valve head (22) can be lowered 
onto or raised from a valve seat (20). In the sealing area to the valve 
seat (20), the valve head (22) is of conical design to achieve a good 
shut-off. On its free, flat end, the valve head (22) can have a disc-like 
element (26) through which fluid can pass but which rejects foreign 
particles. The element (26) is adjusted to the diameter of a pipe section 
(28) of the fitting (12) in which the valve head (22) is movable in such a 
way that a change in the direction of flow is largely precluded. 
The valve housing (14) is screwed into the fitting (12) by means of a 
thread (30). As a limiting device, the valve housing (14) of hollow 
cylinder type has underneath the thread (30) an all-round projection (32) 
which abuts against a step (34) of the fitting (12) when the valve housing 
(14) is screwed in far enough. In this area, there is also an O-ring seal 
(36). If the valve housing (14) has been screwed in far enough, the 
distance between the projection (32) and the free end of the valve seat 
(20) ensures that the valve seat (20) is in sealing contact with a 
ring-like projection (38) of the fitting (12). As a result of this, it is 
ensured that the fluid can flow exclusively through the port (40) in the 
valve seat (20) and can then flow out of the fitting (12) through the 
outlet port (42). 
With regard to the dimensions of the valve housing (14) or the projection 
(32), an adjustment to 1/2" or 3/4" thread is preferably made. 
The valve seat (20) is held by a hollow-cylindrical element (44) containing 
the outlet port (42), with the element being in its turn mountable on--and 
releasable from--the free edge (46) of the valve housing (14). To ensure 
reliable guidance and to prevent unwelcome slippage of the elements in 
relation to one another during installation in particular, the edge (46) 
is provided with a depression to which the facing edge (48) of the element 
(44) is adapted. The interaction is effected by means of steps. 
For the valve head (22) to be lowered onto or raised from the valve seat 
(20) to the required extent, the piston holder (16) is arranged to be 
axially movable inside the valve housing (14) designed as a hollow 
cylinder. For this purpose, the piston holder (16) has at its rear end 
(50)--the bottom end in the drawing--projections (52) preferably arranged 
in a star pattern, as shown in FIG. 12. The projections (52) extend from a 
hollow-cylindrical inner wall (54) having a female thread (56) interacting 
with the male thread of a spindle (58). The projections (52), which are 
separated by slots (60) and so have a certain yield, engage in recesses 
(62) of the inner wall (64) of the valve housing (14). If the spindle (58) 
is now set in rotary motion by a handle (66) or the like, the piston 
holder (16) is forced to make an axial motion which is ensured by the 
interaction of the projections (52) with the recesses (62). 
To permit a low-wear axial motion of the piston holder (16) along the inner 
wall (64) of the valve housing (14), support is afforded by sealing rings 
(68) and (70), so that not only easy movement is achieved, but also a seal 
which ensures that no fluid can penetrate between the valve housing inner 
wall and the piston holder (16). 
The spindle (58) comprises a first external sector (72) and an adjacent 
further sector (74) of greater diameter with the male thread, which 
interacts with the internal thread (56) of the piston holder (16). The 
sector (72) is movable within a cylindrical recess (78) provided coaxially 
to the valve housing axis (76), the recess in its turn being limited by a 
wall (80) on the face side. The sector (72) has on its face a disc-like 
sector (82) of large diameter so that a step is formed between the sector 
(72) and the sector (82). A retaining element (86) having a `U` shape in 
the plan view, as shown in FIG. 10, is now slid through a radial slot (84) 
from the outside of the piston holder (16) into the recess (78), with the 
sector (72) of spindle (58) being enclosed. Since the retaining element 
(86) is provided with a recess (89) corresponding to the diameter of the 
sector (72), it is ensured that when the spindle (58) is moved the 
external sector (82) cannot pass through the retaining element (86). This 
ensures a stroke limitation for the spindle (58) and thus of the piston 
holder (16) or valve piston (18). 
This stroke limitation is determined on the one hand by the wall (80) and 
on the other by the retaining element (86), depending on whether the 
element (82) abuts against the wall (80) or against the disc-like 
retaining element (84). In the limit positions, it is ensured at the same 
time that the valve head (22) is either in sealing contact with the valve 
seat (20) or has the maximum distance from the valve seat (20) (see 
Figs.). In this case, further operation of the handle (66) and thus of the 
spindle (58) connected thereto by means of a screw (88) will no longer 
permit further turning in shut-off valves of conventional design: an 
unwelcome load on the valve cone or valve seat would occur instead (during 
the closing operation) or the handle would be excessively tightened. The 
result would be severe wear and tear and possibly irreparable damage. 
Under the terms of the invention, however, further turning of the handle 
(66) and thus of the spindle (58) is possible, since the projections 
(52)--designed to "yield" to a certain extent--now slide out of the 
recesses (62) over the raised portions (97) between the recessed on the 
inner wall of the valve housing (14) so that the rotary motion of the 
handle (66) is converted directly into a radial motion of the spindle 
(58), without there being a further axial shift of the piston holder (16) 
at the same time. This "jumping" action of the projections (52) over the 
raised portions (97) can however only take place when the disc-like sector 
(82) interacts either with the wall (80) or with the retaining element 
(86). Otherwise, the rotary forces transmitted by the spindle would not be 
sufficient for the projections (52) to jump over the raised portions (97) 
into other recesses (62). 
As soon as the handle (66) is turned in the opposite direction, there is a 
direct axial motion of the piston holder (16) and thus of the valve piston 
(18) so that no time-lag occurs in the opening or closing motion. 
A disc (90) arranged on the lower face of the valve housing (14) ensures 
that the spindle (58) itself is not axially adjustable. 
To ensure that fluid cannot flow back through the outlet port (92) of the 
fitting (12) and back into the connected pipework, a sealing element (94) 
is provided that serves as a non-return valve. The sealing element (94) on 
the one hand encloses the valve piston (18) and on the other hand is moved 
by a spring element (96) in the direction of the valve seat (20). The 
disc-like sealing element (74) is designed as a collar and abuts in 
sealing contact against an inward-facing sector (98) of the cylinder-like 
element (74), which in its turn holds the valve seat (20) on the outside. 
The force of the spring element (96) is selected such that the port (40) 
through the element (94) is normally closed. This ensures that fluid 
penetrating through the port (92) cannot flow back into the piping system. 
The element (96) does not lift off from the sector (98) until the force 
exerted by the fluid flowing in the direction of the arrow exceeds that of 
the spring element (96), so permitting fluid to pass into the fitting (12) 
in the normal way. 
The valve housing (14), the spindle or shaft (58), the piston holder (16), 
the valve seat (20), the valve piston (18) and the sealing element (96) 
are arranged recognizably coaxial to one another along the axis (76). The 
valve piston (18) is snapped into a recess (100) in the area of the piston 
holder (16) facing the valve seat (20). For this purpose, the valve piston 
(18) has at its lower end a bulge-like reinforcement (102) which is placed 
in the recess (100) mentioned through slots (not shown). This not only 
ensures easy assembly, but also permits a relative movement between the 
elements. This results in a good seal between the valve seat (20) and the 
valve head (22). Should scale, for example, build up in this area, the 
valve head (22) can be tilted in order to permit an equalization and so 
ensure shutoff. 
In FIG. 3, a further embodiment of the shut-off valve according to the 
invention is shown, also installed in a fitting (12). Unlike the 
embodiment according to FIG. 1, the element (44) of hollow cylinder design 
holding the valve seat (20) extends beyond the valve seat (20) in order to 
pick up a cup-like element (104) that bounds a chamber (106) in which the 
valve head (22) is axially movable. The connection between the elements 
(44) and (104) is made by fitting them together. For this purpose, sectors 
of wall (108) and (110) run parallel to one another and are seated on one 
another by means of steps. The walls (108) and (110) accordingly form 
external or internal walls of the elements (44) and (104) shaped as hollow 
cylinders in this area. The latter element is covered by a disc (112) 
which is permeable to a fluid but which rejects foreign bodies. 
The valve housing closed off with the cup-like element (104) is now 
inserted into the fitting (12) in such a way that a tubular sector (114) 
abuts tightly against the face of the element (104) to ensure that the 
fluid can pass exclusively in the direction of the arrow through the 
chamber (106) to the outlet port (42) or (92). The advantage of this 
configuration is that the valve head (22) in the chamber (106) is movable, 
without an adjustment being made to the fitting (12); normally, the valve 
head (22) moves within a tubular sector of the fitting (12) as in made 
clear in FIG. 1 too. 
In FIG. 4, a further noteworthy and independent variant of the invention is 
shown. To permit change of the distance between the fastening areas of the 
shut-off valve in the fitting, i.e. between the valve seat (20) and the 
projection (32) in the embodiment according to FIG. 1, a stop element 
(118) in the form of a cap nut and also having a projection (116) outwards 
is provided which can be screwed onto a thread (122) of an intermediate 
element (120) which in its turn is designed as a hollow cylinder and is 
mounted on the outer wall of the valve housing (14). It is possible to 
connect the element (120) and the valve housing (14) in the manner of a 
slip clutch, so that the torque is limited when the element is being 
screwed on if non-permissible forces are applied. The slip clutch can be 
designed as a system of interacting projections and recesses, whereby the 
projections jump into adjacent recesses--i.e. the thread (122) carries out 
an exclusively radial motion--when the applied screw forces exceed a set 
value. 
FIG. 7 shows a variant of a stop element (124). The stop element can be 
screwed to the outer wall of the valve housing (14) using a thread (126). 
In the lower portion, the stop element (124) is surrounded by a kind of 
retaining nut (128) which engages with its upper free end (130) in a 
recess in the lower edge such as the groove (132) all round the stop 
element (124). At the lower end, the element (128) is supported by the 
outer wall of the valve housing (14). Around the groove (132), element 
(124) and thread (128) interact as a kind of slip clutch. The free end 
(130) engaging in the groove (132) has projections--not shown--extending 
from it that engage in recesses on the inner wall of the groove (132). If 
the retaining nut (128) is now gripped on the outside and set in rotary 
motion, the stop element (124) is moved towards or away from the seal (36) 
depending on the direction of rotation. As soon as the projection (134) 
contacts a stop--not shown--in a fitting and is firmly abutting against 
it, the slip clutch comes into action; this means that the projections of 
the retaining nut (128) jump from recess to recess inside the groove (132) 
and so transmit the rotary motion of the retaining nut (128) to the stop 
element only in such a way that the stop element (124) as cap nut carries 
out an exclusively radial motion. It is accordingly possible with this 
embodiment of the shut-off valve according to the invention to adjust it 
to fittings with non-standard dimensions. 
FIG. 6 shows an embodiment relating to the connection between the valve 
piston (18) and the piston holder (16). The valve piston (18) is fitted 
onto the piston holder (16) in such a way that there is a coaxial relative 
movement between the two elements, i.e. they can be rotated against one 
another along a common surface about the valve axis. For this purpose, the 
piston holder (16) has a cap-like end section (136) formed by an all-round 
groove (137) and surrounded by a suitably shaped bottom section (138) of 
the valve piston (18) in such a way that the free coaxial motion is 
possible. In other words, the sector of the valve piston (18) facing the 
piston holder (16) is designed as a hollow cylinder with the edge (139) 
facing inwards. This edge is partially removed to allow it to be fitted 
laterally onto the end section (136). The inward-facing edge then engages 
in the groove. The mode of connection between the valve piston (18) and 
the piston holder (16) can be regarded as a radially extending dovetail 
connection. This design ensures that a rotary motion of the piston holder 
(16) is possible when the valve piston (18) is frozen tight, for example, 
so precluding any breakage of the valve piston (18). 
FIG. 6 also shows a further especially noteworthy feature relating to the 
connection between the piston holder (16) and the spindle (58). In 
comparison with the embodiment in FIG. 1, the spindle (58) is not 
releasably connected by a retaining element; instead the spindle (58) has 
a bulge (61) surrounding it at a distance from the inner wall (59) on the 
bottom side, said bulge being gripped from behind by two sectors (63) of 
the piston holder (16) projecting in the direction of the spindle (58) and 
preferably arranged diametrically (it is of course also possible to 
provide one surrounding sector or more than two sectors). The connection 
between the piston holder (16) and the spindle (58) can be seen in the 
form of a snap fastening. The connection itself must be made outside the 
valve housing (14) in order to then slide the unit of piston holder 
(16)/spindle (58) axially into the valve housing (14), as otherwise the 
sectors (63) can no longer grip behind the bulge (61). (Between the 
sectors (63) forming diametrically arranged projections, preferably two 
further diametrical projections facing outwards are provided which 
interact with the grooves provided axially in the inner wall of the valve 
housing to form the slip clutch described in FIG. 1.) 
The bulge (61) itself also limits the stroke of the piston holder when the 
bulge (61) abuts against the inward-facing sector (63). In this position, 
the valve is completely opened in the embodiment according to FIG. 6. The 
other limit position of the piston holder (16) and thus of the valve 
piston (18) is achieved when the internal and free face wall (65) 
interacts with a bottom wall (67) of a recess (69) in the piston holder 
(16), with the cylindrical recess (69) surrounding the spindle (58). In 
this area, the spindle has a male thread and the inner wall of the recess 
(69) a female thread, to effect the required axial motion of the piston 
holder (16) when the spindle (58) make a rotary motion. 
The advantage with this connection of spindle (58) and valve holder (16) is 
that apart from the bulge (61) and a bulge serving as a limit (71) and 
abutting against the bottom surface (58) of the valve housing (14), the 
diameter of the spindle (58) is constant. The result of this is extreme 
stability. There is also the advantage that use in industrial valves in 
particular is possible. FIG. 5 illustrates a shut-off valve where the 
valve head (22) is arranged movably in a chamber (140) which is bounded by 
an element (142) designed in cup form and having cylindrical walls, and 
which corresponds to the element (104) in FIG. 3. On the face side, the 
element (142) has an all-round seal (144) which is in sealing contact with 
a sector of a fitting, in the same way as the seal (36) on the step (34) 
of the valve housing (14). The face side of the element (142) has a port 
(146) through which fluid can flow. This port (146) is now closed by an 
element (148) which serves as a non-return valve. The element (148), shown 
in greater detail in FIGS. 8 and 9, has a disc-like base element (150) 
which can close the port (146) tight on the valve side. For this purpose, 
a sealing ring (156) can be inserted additionally in an all-round groove 
(152). The diameter of the disc-like base element (150) is also greater 
than the clear diameter of the port (146). FIG. 5 shows that the disc-like 
base element (150) abuts against the valve head (22) surface which is flat 
on the outside and vertical to the longitudinal axis of the valve. In 
order however to prevent any sticking of the element (148) inside the 
chamber (140), four projections (154) extend from the base element (150) 
and slide along the inner wall (158) of the chamber (140), i.e. of the 
cup-like element (142). In addition, projections (160) and (162) extend 
from the base element (150) that are formed by webs and that intersect at 
right angles, giving a cross-like pattern in the plan view, these 
projections (160) and (162), termed wings, slide along the inner wall 
(164) of port (146), which also ensures that tilting is prevented. If a 
fluid now flows through the port surrounding the valve seat (20) against 
the normal flow direction into the chamber (140), the element (148) is 
gripped and so seals the port (146). 
Although the embodiments describe the invention on the basis of a 
sanitation fitting, applications in a wide variety of fields are possible. 
Preferred applications are physics or chemistry laboratories where 
shut-off valves are used for regulation of liquids and gases. Particularly 
the fact that the shut-off valve in accordance with the invention is 
constructed of plastic affords the advantage that it can be used wherever 
corrosive fluids are encountered. Since the design and the material are 
only subject to minor wear, and overtightening of the valve--in whatever 
direction--is not possible, the shut-off valve under the terms of the 
invention requires very little maintenance and ensures a high degree of 
functionality.