Diaphragm valve with an elastic diaphragm braced by a valve cover

Diaphragm valve with an elastic diaphragm, which is penetrated by at least one balance hole, braced sealingly on the side of the rim by a valve cover, and which closes a pressure vessel and can be moved by setting the pressure on both sides between the valve cover and the mouthpiece of an exhaust pipe; in the closed state said diaphragm valves abuts the mouthpiece sealingly and in the opened state is bent due to the excess pressure on its side toward the valve cover facing away from the valve cover, wherein in the opened state a hole, opposite the diaphragm, in the valve cover is opened by a control valve and is closed in the closed state so that the pressure in the pressure vessel acts on one side of the diaphragm only when the control valve is open and lifts said diaphragm from the moutpiece. The valve cover on its side facing the diaphragm is designed as a substantially flat plate and the diaphragm is provided on its side facing the valve cover with a projection arranged coaxially to the mouthpiece, around which projection the diaphragm bends or straightens when opening and closing.

The invention relates to a diaphragm valve with an elastic diaphragm, which 
is penetrated by at least one balance hole, braced sealingly on the side 
of the rim by a valve cover, and which closes a pressure vessel and can be 
moved by setting the pressure on both sides between the valve cover and 
the mouthpiece of an exhaust pipe; in the closed state said diaphragm 
valve abuts the mouthpiece sealingly and in the opened state is bent due 
to the excess pressure on its side toward the valve cover facing away from 
the valve cover, wherein in the opened state a hole, opposite the 
diaphragm, in the valve cover is opened by a control valve and is closed 
in the closed state so that the pressure in the pressure vessel acts on 
one side of the diaphragm only when the control valve is open and lifts 
said diaphragm from the mouthpiece. 
Such a diaphragm valve is known from DE OS 33 03 003. To give the diaphragm 
of this diaphragm valve adequate play, the valve cover has a recess which 
encloses the hole in the valve cover and passes over into a prominence 
that extends like a ring relative to the valve cover surface adjoining it. 
This annular prominence on the valve cover pushes in the closed state of 
the diaphragm valve the diaphragm against the mouthpiece of the exhaust 
pipe, whereas in the opened state due to the hole in the valve cover that 
is opened by the control valve the pressure in the pressure vessel pushes 
the diaphragm into the recess, thus lifting the diaphragm from the 
mouthpiece. 
The invention is based on the problem of simplifying the construction of 
the diaphragm valve under discussion, which must be addressed as a 
mass-produced article. This problem is solved by the invention in that the 
valve cover is designed on its side facing the diaphragm as a 
substantially flat plate and the diaphragm on its side facing the valve 
cover is provided with a projection arranged coaxially to the mouthpiece, 
around which projection the diaphragm bends or straightens out when 
opening and closing. 
Since the diaphragm is designed with the coaxial projection, the clearance 
of motion to be given to the diaphragm is shifted away from the valve 
cover so that the valve cover can be designed as a flat plate, a feature 
which represents a significant simplification of the design of this part. 
The special design of the diaphragm does not play a role, since this 
diaphragm is a moulded part made of an elastic plastic or rubber that is 
to be extruded or vulcanized in the typical manner and for whose 
manufacture an adapted shape is necessary in every case. 
Various possible designs exist for the projection included in the 
diaphragm. Thus, the diaphragm can be provided on its side facing the 
valve cover with a projection around which the diaphragm bends or 
straightens out when opening and closing. In this case the projection 
forms simultaneously the seal of the diaphragm relative to the valve 
cover. However, it is also possible to design the projection in the shape 
of a collar so that due to the pot wall the result is a space between the 
actual diaphragm and the surface of the valve cover facing said diaphragm. 
Preferably the diaphragm has in the region of the mouthpiece a 
reinforcement, wherein the region exploiting the elasticity of the 
diaphragm material is displaced outwardly radially away from the 
mouthpiece. In the region of the mouthpiece, the diaphragm can abut 
without bending and seal said mouthpiece.

The diaphragm valve shown in FIG. 1 comprises valve cover 1 and elastic 
diaphragm 2, which is braced on the rim of valve cover 1 and fastened here 
by means of attachment elements, which are indicated by the dashed-dotted 
lines 3 and 4. It can also involve continuous screws, which penetrate rim 
5 of diaphragm 2 and are screwed into the wall of a pressure vessel 6. 
Pressure vessel 6 is shown here only with its part facing the diaphragm 
valve; its interior is denoted as 7. In this manner it is achieved that in 
the region of rim 5 of diaphragm 2 the result is a seal both of pressure 
vessel 6 with respect to diaphragm 2 and also between this diaphragm and 
valve cover 1. 
Diaphragm 2 is provided with torus 8, which projects from said diaphragm 
and is designed as one piece with diaphragm 2. In this case it involves a 
part extruded of elastic plastic or a part vulcanized of rubber. Diaphragm 
2 is designed in its central region as a reinforcement 9, thus largely 
taking the elasticity from it in this region. In the region between 
reinforcement 9 and torus 8, diaphragm 2 has several balance holes 10, 
which make it possible for the pressure medium located in pressure vessel 
6 to penetrate through balance hole 10 into interspace 11 between 
diaphragm 2 and valve cover 1. 
Valve cover 1 has hole 12, which lies opposite diaphragm 2 and serves to 
form a connection from interspace 11 to the environment of the diaphragm 
valve depending on whether control valve 13 does or does not seal with its 
seal 14 hole 12. 
FIG. 1 shows the diaphragm valve in the closed state in which diaphragm 2 
abuts mouthpiece 15 of exhaust pipe 16. In this closed state control valve 
13 seals with a seal 14, as shown, hole 12 so that the pressure indicated 
by arrow 17 can extend over balance bores 10 into interspace 11. Thus, the 
same pressure acts on both sides of diaphragm 2 so that, owing to an 
inherent prestress, which said diaphragm acquires through assembly, 
diaphragm 2 abuts sealingly mouthpiece 15 of exhaust pipe 16 and thus 
closes it. When assembling diaphragm 2, it is bent especially with its rim 
5 around torus 8 in the direction of valve cover 1, thus resulting in a 
prestress in diaphragm 2 due to the elasticity of the diaphragm material, 
said prestress pushing, as stated, this diaphragm against mouthpiece 15 of 
exhaust pipe 16. 
FIG. 2 shows the same diaphragm valve in the opened state. In this state 
the control valve 13 is lifted with its seal 14 from hole 12 so that the 
pressure from the interspace 11 can escape, according to the drawn arrow, 
in hole 12 to the environment. Due to the small cross-section of balance 
holes 10, this equalization of pressure on the way from interior 7 through 
balance holes 10 into interspace 11 and thereafter through hole 12 results 
in a pressure drop, which in pressure vessel 6 leads to excess pressure 
with respect to the pressure in interspace 11 so that diaphragm 2 bends 
under the effect of this excess pressure in the direction of valve cover 
1. At the same time diaphragm 2 is lifted from mouthpiece 15 of exhaust 
pipe 16, thus opening the diaphragm valve. When diaphragm 2 moves in this 
manner, this diaphragm continues to bend around torus 8, thus further 
increasing the prestress in diaphragm 2, which is, of course, balanced by 
the excess pressure acting on diaphragm 2 from interior 7. The 
cross-section of hole 12 which is substantially larger than the 
cross-section of balance holes 10 provides that, when control valve 13 is 
lifted, the pressure ratios responsible for lifting diaphragm 3 are 
maintained constantly on both sides of said diaphragm. 
As apparent, valve cover 1 comprises only a flat plate on the side facing 
diaphragm 2, said plate being made in the typical manner of metal, in 
particular aluminum. Thus, it involves a component that is quite simple to 
manufacture. 
FIGS. 3 and 4 show a variation of the diaphragm shown in FIGS. 1 and 2. The 
other parts of the diaphragm valve are designed in the same manner as 
those of the embodiment of FIGS. 1 and 2 so that the same reference 
numerals can also be used. The function of the respective diaphragm valve 
is also the same in both cases. 
The diaphragm valve of FIGS. 3 and 4 has here diaphragm 18, which in the 
region between reinforcement 9 and rim 5 has a collar-like annular part 
19, which gives diaphragm 18 the requisite elasticity for raising it from 
exhaust pipe 16 and returning it on said exhaust pipe. 
FIG. 3, which shows the closed position of the diaphragm valve, shows 
annular part 19 as stretched. FIG. 4, showing the opened position, shows 
annular part 19 as slipped over in which position it is held by the excess 
pressure on the side of the interior 7 against its inner prestress that 
has been generated as a result.