Shutoff and regulating valve

A shutoff and regulating valve contains, in a housing (2), a shutoff element which is designed especially as a stopcock (8) and which is arranged to be rotatable by means of a stem (26). The stem (26) is guided outward through a housing cover (20), a first sealing element (50) being provided for sealing purposes. The valve is designed for a minimized leakage rate and high safety requirements. The first sealing element (50) is supported on the underside of the housing cover (20) by an annular disk (54), and a second sealing element (60) is arranged on the upper side of the cover (20), so as to be adjustable, particularly by means of an axially movable bush (62).

The present invention relates to a shutoff and regulating valve with a 
shutoff element designed as a stopcock, a housing in which the shutoff 
element is arranged rotatably by means of a stem, a housing cover through 
which the stem extends outwardly so as to be sealed off by means of a 
first sealing element, and a second sealing element arranged on the 
surface of the cover. 
BACKGROUND OF THE INVENTION 
West German Patent No. DE 2,742,115 discloses a shutoff and regulating 
valve of this type, the stem of which is sealed off by means of two 
sealing elements arranged in the housing cover. The cover has an annular 
groove on its underside into which the first sealing element is inserted. 
Arranged between the stem and the stopcock is an intermediate piece having 
a T-shaped cross section which engages into a square recess of the 
stopcock. This intermediate connecting piece, on its upper side facing the 
stem, has a larger diameter than the stem. The first sealing element rests 
on the upper side of the connecting piece, and the sealing effect of the 
first sealing element is dependent on the axial position of the connecting 
piece and/or of the stem. Since the axial position of the stem varies as a 
result of production tolerances, abrasion, external forces and the like, 
difficulties can arise with regard to safety regulations and environmental 
protection regulations, in ensuring that the requisite limiting values for 
leakage rates can be maintained even throughout a long lifetime. If the 
shutoff element is adjustable in the direction of the stem axis, 
particularly if the stopcock is of conical design, additional difficulties 
can arise. The conical sealing faces of the stopcock interact with a bush 
which is appropriately pressed into the housing and which is normally 
composed of polytetrafluoro-ethylene (PTFE) or a comparable material. 
During assembly, the stopcock has to be adjusted in the direction of the 
stem axis, in order to assure a sealing contact. In previously known 
constructions, during this adjustment, stress was also exerted on the 
first sealing element of the stem, and in practice an excessive pressing 
of the first sealing element against the stem was often found. This 
resulted in excessive wear of the first sealing element, with the result 
of an appreciably reduced lifetime and a diminished sealing effect. 
SUMMARY OF THE INVENTION 
It is therefore the object of the present invention to provide a shutoff 
and regulating valve of the aforementioned type which can be produced at 
low cost. 
It is also an object of the present invention to provide a shutoff and 
regulating valve which minimizes leakage rates and satisfies strict safety 
requirements. 
Another object of the invention is to provide a shutoff and regulating 
valve in which, after an unacceptable leakage flow has occurred and been 
detected, an additional sealing can take place, so that the shutoff valve 
does not have to be replaced immediately, but only after a predetermined 
time, e.g. during the next routine shutdown of the apparatus. 
Yet another object of the invention is to provide a shutoff and regulating 
valve which has a high functional reliability and a long service lifetime, 
and which facilitates simple exchange and replacement of damaged 
components. 
These and other objects of the invention are achieved by providing a 
shutoff and regulating valve with a shutoff element designed especially as 
a stopcock, with a housing in which the shutoff element is arranged 
rotatably by means of a stem, and with a housing cover, through which the 
stem is guided outward so as to be sealed off by means of a first sealing 
element, a second sealing element being arranged on the surface of the 
cover, wherein the first sealing element is supported on the underside of 
the cover on an annular disk. 
The proposed shutoff and regulating valve has a simple and nevertheless 
functionally reliable design. Because the first sealing element is 
supported independently of the instantaneous axial position of the stem or 
of the shutoff element, to that extent they are prevented from influencing 
one another, so that the first sealing element exerts the sealing effect 
as effectively as possible. Because the first sealing element is supported 
by means of the annular disk, specific relationships are provided for the 
first sealing element independently of the depth of adjustment of the 
stopcock in the housing. This brings about reproducible conditions both 
for the sealing ring of the stopcock in relation to the housing and in 
terms of the first sealing element for the stem, so that a reliable 
sealing is assured at a low production cost and with a small structural 
volume. By means of the second preferably readjustable sealing element, it 
is possible at a minimum production cost, after an unacceptable leakage 
flow has been detected, to prevent this for a predetermined period of 
time. The sealing element performs virtually no sealing function in the 
normal operating state or state of adjustment. The second sealing element 
is assigned a readjusting device which, when required, is actuated in such 
a way that these additional sealing means can exert their sealing effect. 
It should be stated, here, that the primary sealing elements rest against 
the stem in a way known per se and thus ensure sealing relative to the 
outside. As a result of the mechanical contact of the primary sealing 
element with the stem, this sealing element, which usually is composed of 
an elastomeric material, experiences wear dependent particularly on the 
number of stem actuations. 
In an especially advantageous embodiment, the shutoff element designed as a 
stopcock is adjustable relative to the stem in the direction of the 
longitudinal axis of the housing and therefore in the flow direction. 
Because of this adjustability, the stem is substantially isolated from 
forces caused by the flow. The result of this is that, even during normal 
operation, the primary sealing elements of the stem are less subject to 
stress. In particular, the result of subjecting the stem to force via the 
stopcock is that a higher bearing force is exerted between the primary 
sealing element and the stem, primarily, in the flow direction than in 
other directions, with the result that greater wear takes place at the 
primary sealing element. These disadvantages are avoided in a simple way 
by the two-part design of the stem and stopcock and the movability of the 
latter relative to the stem.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT 
FIG. 1 shows, in an axial plane, a section through a housing 2 with flanges 
4, 6 which are arranged at the axial ends and by means of which the 
connection to a pipeline system can be made in the usual way. In the 
housing 2, a stopcock 8 is rotatable about an axis 10 in order to open or 
shut off a channel 12 which extends throughout the housing 2. To seal the 
stopcock 8 relative to the housing, a bush 15 with a lower sealing strip 
14 and an upper sealing strip 16 is pressed into the housing. The housing 
2 has an orifice 18 which is closed off by means of a cover 20. As 
indicated by the broken lines 22, the cover 20 is connected firmly to the 
housing 2 and in the center contains a bore 24, through which a stem 26 is 
guided. In contrast to the previously known stopcock valves, according to 
the present invention, the stopcock 8 and the stem 26 are designed as 
separate parts, the stem 26 engaging at its end 28 in a recess 30 in the 
stopcock 8. It is essential, here, that the end 28, which is formed, for 
example, as a square engages in the recess 30 with play, as indicated by 
the gap 32. This ensures that the stopcock 8 will be decoupled from the 
stem 26, so that the stem is substantially isolated from forces exerted on 
the stopcock 8 by the flowing medium. The stopcock 8 is supported 
virtually exclusive of the bush 15 by means of the sealing strips 14, 16 
in the direction of the longitudinal axis 34, that is to say orthogonally 
relative to the stem axis 10. The sealing elements, which are explained 
further below, provided for sealing the stem are consequently subjected to 
less stress, and in particular locally excessive surface pressures and 
therefore increased wear are avoided in a simple way. 
Stopcock 8 rests with conical sealing faces against the PTFE bush 15 with 
sealing strips 14, 16. The stopcock is adjustable or settable in the 
direction of the axis 10, in order to ensure good sealing without 
excessively high surface pressures. For this purpose, the stem 26 has a 
collar 36 which rests against the end surface 38 of the stopcock 8. The 
stem 26 is biased relative to the cover 20, and therefore relative to the 
housing, in the direction of the axis 10 towards the stopcock 8 via mount 
40. The mount 40 rests indirectly on an annular shoulder 42 of the stem 26 
via an annular body 44 made of PTFE. The mount 40 is arranged on the cover 
20 by means of screws 46 and can be adjusted in the direction of the stem 
axis 10 by rotating nuts 48. 
The first sealing element for sealing the stem 26 relative to the cover 20 
is a sealing ring 50 which rests against the stem 26 by means of a 
hook-shaped sealing lip 52. It is essential that the sealing ring, and 
particularly the sealing lip 52, be supported on an annular disk 54. The 
sealing ring 50 is therefore not supported axially, for example, by the 
annular collar 36 of the stem, and thereby achieves the same sealing 
effect independently of the axial adjustment of the stem or of the 
stopcock 8. The annular disk 54 and the sealing ring 50 are appropriately 
pressed into an annular groove 56 on the underside of the cover 20 in the 
manner of a stack and are connected firmly to the cover. This reliably 
prevents the primary sealing element or sealing ring 50 from coming loose 
inadvertently or even being "forgotten" in the course of assembly or 
during inspections. 
According to the invention, the stem 26 has associated therewith a second 
sealing element which is designed as a sealing ring 60 and which is 
arranged readjustably on the upper end of the cover 20. For readjusting 
the sealing ring 60, which here has an approximately triangular cross 
section, a bush 62 is provided which is arranged in the bore 24 by means 
of an external thread 64 engaged with a corresponding internal thread on 
the upper cover edge. The bush 62 projects upwards beyond the cover 20 and 
contains recesses 68, into which a tool for rotating the bush 62 can be 
inserted. According to the invention, the second sealing element or 
sealing ring 60 is preadjusted by means of the bush 62 during normal 
operation in such a way that it does not achieve its full sealing effect. 
The sealing ring 60 therefore rests comparatively loosely against the stem 
26, and there is virtually no appreciable wear or abrasion of the sealing 
ring 60, which is composed of an elastic sealing material, an elastomer or 
rubber. The actual sealing effect is predetermined by means of the first 
sealing element or the sealing ring 50. When the sealing effect of the 
sealing ring 50 decreases in the process of time, this is detected by the 
attendants. By tightening the bush 62, the sealing ring 60 can then be 
adjusted on the stem 26 in a way necessary to prevent an unacceptable 
escape of the medium along the stem for some time to come. The shutoff 
valve can still be used for a certain amount of time, without the pipeline 
system or a complex apparatus immediately having to be shut down entirely. 
The necessary repair or replacement, whether of the sealing elements, the 
stopcock or the entire shutoff valve, is then carried out during the next 
routine inspection work. 
According to one preferred embodiment, an annular chamber 70 is provided 
for monitoring purposes axially between the two sealing rings 50, 60 and 
radially between the stem 26 and the inner wall of the bore 24 in the 
cover 20. As indicated by the dashed line 72, chamber 70 is connected via 
a passageway to an instrument 74 for monitoring leakage. With this 
instrument 74, it is possible, for example, to sense whether and to what 
extent the medium flowing in the channel 12 is escaping. This can be 
carried out especially electrically or pneumatically, whereby in the 
vicinity of the annular chamber 70 appropriate sensors are provided for 
sending corresponding signals to the instrument 74. Even with such leakage 
monitoring, it is basically sufficient during normal operation to ensure 
that the sealing ring 60 rests against the stem 26 with a low pressing 
force in order to achieve a minimum wear. Should the sealing ring 50 
become leaky, the medium enters the annular chamber 70, and this fact is 
indicated by means of the instrument 74. 
Furthermore, as indicated by the broken lines 57, a plate 58 or the like 
for fastening an actuating drive, not shown further here, is arranged 
above the cover by means of bolts. The stem 26 can be rotated about the 
axis 10 in the necessary way by means of the hydraulically, pneumatically 
or electrically operated actuating drive. It is essential, here, that, as 
represented by the lines 57, the actuating drive is connected directly to 
the cover 20, specifically independently of the connection of the cover to 
the housing as indicated by the lines 22. This results in an advantageous 
decoupling which is desirable not only in terms of the vibration behavior 
Also, an inadvertent loosening of the cover 20 during possible measures to 
mount the actuating drive can be prevented. 
In one preferred embodiment, the stopcock 8 has bores 73 extending between 
the passage 75 and the spaces 18 and 19 located, respectively, above and 
below the stopcock 8. Spaces 18 and 19 are thus subjected to pressure or 
pressure-compensated. The end face of the stopcock 8 is larger in the 
upper space 18 than in the lower space 19. These faces of differing size 
produce a force component which acts axially on the stopcock and by means 
of which the stopcock 8 is pressed firmly into its seat, thereby achieving 
an increased radial sealing force. So that the stopcock 8 is prevented 
from being pressed too deeply into the bush 15, there is a bottom disk 77 
in the lower space 19 which, in accordance with the invention, forms a 
stop and limits the downward travel of the stopcock 8. 
Even when, in an alternative embodiment, there are no bores 73 leading to 
spaces 18 and 19, the bottom disk 77 still proves to be very important. In 
particular, if a leak occurs between the stopcock 8 and the bush 15 with 
sealing strips 14 and 16, the upper space 18 is subjected to pressure, 
with the result that the stopcock 8 is pressed into the seat. The 
resulting increased sealing force between the stopcock 8 and the bush 15 
is usually sufficient to stop the leakage which has occurred. The bottom 
disk 77, although not being absolutely necessary under these 
circumstances, nevertheless has proved appropriate as an advantageous form 
of a stop. The bottom disk 77, which is inserted into the space 19 under 
the stopcock, is itself advantageously composed of PTFE or a comparable 
material. 
FIG. 2 illustrates a stopcock valve in which the adjustment of the stopcock 
8 is effected on the opposite side of the housing 2 from the stem 26. Once 
again, the sealing faces of the stopcock 8 are conically formed with the 
cone apex on the same side as the stem 26 in relation to the longitudinal 
axis 34. The smaller sealing strip 14 of the bush 15 is now arranged in 
the space 18, while, as shown in the drawing, the larger sealing ring 16 
is arranged on the underside of the housing in an opening 76, which is 
closed off sealingly by means of a cover 78. For the adjustment and 
setting of the stopcock 8, there is a threaded bolt 80 in the cover 78 
which acts from below on the stopcock 8 via a sealing diaphragm 82 and a 
pressure body 84. The pressure body 84 is advantageously composed of a 
material having good sliding properties, particularly PTFE. The threaded 
bolt 80 has a recess, for example for a hexagon-socket wrench, at its 
lower end 86 and is held in place by means of the lock nut 88. 
In this preferred embodiment according to the invention, the stopcock 8 
also is movable relative to the stem 26 in such a way that, on the one 
hand, the stopcock is rotated by means of the stem and, on the other hand, 
the stopcock is decoupled from the stem with respect to forces exerted in 
the direction of the longitudinal axis 34. For this purpose, the stopcock 
8 has a recess 30 in its end facing the stem 26, appropriately in the 
region sealed by means of the sealing ring 14. A connecting body 90 having 
an approximately T-shaped contour is inserted in this recess 30. The 
connecting body 90, with its lower part represented by broken lines here, 
engages in a groove 92 respectively in front of and behind the drawing 
plane and is movable with some play in this groove 92 perpendicularly 
relative to the drawing plane. The upper central part of the body 90 
engages with play in a square recess 94 in the stem 26, the gap 32 once 
again being present in the direction of the longitudinal axis 34. 
The stem 26 is again arranged rotatably in the cover 20, sealing being 
obtained by means of the first and second sealing elements or sealing 
rings 50, 60. In addition, an intermediate ring 96 is provided between the 
cover 20 and the housing 2 in order to axially secure both the annular 
disk or thrust ring 54 and the sealing ring 50. The annular disk 54 
projects radially inward near to the outer circumference of the stem 26. 
This assures that the sealing ring 50 is supported and secured reliably, 
there being arranged within the hook-shaped sealing lip 52 a thrust ring 
53 which is likewise mounted and supported reliably on the annular disk 
54. It is essential, furthermore, that, in interaction with the annular 
collar 36, the stem 26 is also secured axially by means of the annular 
disk 54. The annular collar 36 has an outside diameter which is larger 
than the inside diameter of the annular disk 54. Advantageously, a ring 98 
with good sliding properties, formed for example of PTFE, is arranged 
between the annular collar 36 and the annular disk 54, so that the stem 26 
can be rotated by exerting only a small amount of force. 
As already explained above, the sealing ring 60 is held in place by means 
of the axially adjustable bush 62. This purpose is served by a mount 100 
which is arranged on the upper edge of the cover 20 and which rests with 
its lower edge 102 on the upper end face of the bush 62. As illustrated, 
the lower edge 102 is beveled slightly conically, so that, in practice, 
there are two bearing points on the bush 62. As a result of these bearing 
points or regions, which advantageously lie in a plane orthogonal relative 
to the longitudinal axis 34, an essentially centric force transmission is 
assured, thereby avoiding the danger of a canting or jamming of the bush 
62. 
The foregoing description has been set forth merely to illustrate the 
invention and is not intended to be limiting. Since modifications of the 
described embodiments incorporating the spirit and substance of the 
invention may occur to persons skilled in the art, the scope of the 
invention should be limited solely with respect to the appended claims and 
equivalents.