Vacuum valve with gas-tight shaft penetration

1. A vacuum valve for interrupting, releasing or regulating a flow of a medium flowing along a flow path in an inner region of the vacuum valve, having

a valve housing, which separates the inner region of the vacuum valve in a gas-tight manner from the atmosphere region outside the vacuum valve,

a valve drive for generating a movement in the atmosphere region,

a shaft,

which is coupled to the valve drive,

which has a geometrical shaft axis,

which is routed in a gas-tight manner from the atmosphere region into the inner region, through the valve housing, by way of a sealing shaft feedthrough, and

by means of which the movement can be transmitted from the atmosphere region into the inner region, and

a valve closure, which is arranged in the flow path in the inner region,

which is coupled to the shaft, and

by means of which the operation of interrupting, releasing or regulating the flow of the medium flowing along the flow path can be brought about by the movement,

wherein the shaft feedthrough has

a first sealing ring,

which consists of a material which expands under the action of heat, and

which encloses the shaft concentrically with gas-tight sealing in the radial direction,

a bearing surface,

which is coupled to the valve housing and encloses the shaft,

which is oriented axially in relation to the shaft and runs substantially in a plane to which the geometrical axis of the shaft forms a normal, and

on which the first sealing ring rests with gas-tight sealing such that the first sealing ring is fixed axially in a direction parallel to the shaft, wherein the first sealing ring rests on the bearing surface with gas-tight sealing in the axial direction and the first sealing ring gives rise to gas-tight contact between the bearing surface and the shaft,

a supporting ring,

which consists of a substantially rigid material,

which is arranged concentrically all the way round the shaft, and axially opposite the bearing surface,

which can be moved axially to a limited extent relative to the bearing surface, to the valve housing and to the shaft, and

which has, on a portion oriented toward the bearing surface, an inner conical segment, which

runs concentrically around the shaft and encloses the same,

widens with a cone-opening angle in the direction of the bearing surface, and

at least partially encloses the first sealing ring all the way round, and

an elastic spring, which forces the supporting ring axially in the direction of the bearing surface such that the conical segment forces the first sealing ring in an elastically compliant manner, and substantially under constant contact pressure, onto the bearing surface and the shaft, wherein the cone-opening angle is such that radial expansion of the first sealing ring brought about by the first sealing ring being subjected to the action of heat gives rise to an axial movement of the supporting ring in the direction away from the bearing surface, and wherein the elastic spring is designed such that the elastic spring yields to the axial movement of the supporting ring brought about by the radial expansion,

wherein

the first sealing ring is designed as a first O-ring,

as seen in the axial direction, there is substantially annular, sealing contact between the first O-ring and the bearing surface,

as seen in the radial direction, there is substantially annular, sealing contact between the first O-ring and the shaft, and

as seen in the direction which is oblique in relation to the bearing surface and to the shaft, there is supporting contact between the first O-ring and the inner conical segment of the supporting ring.

2. The vacuum valve as claimed in claim 1 ,

wherein

a second sealing ring, which is arranged between the supporting ring and the shaft, on a portion of the supporting ring which is oriented away from the bearing surface, and

a lubricant region, which is formed between

the first sealing ring,

the second sealing ring,

the shaft, and

the supporting ring

for the purpose of accommodating a lubricant for generating a sealing film with grease between the shaft and the first seal.

3. The vacuum valve as claimed in claim 2 ,

wherein

the portion of the supporting ring which is oriented toward the bearing surface is directed toward the inner region, and

the supporting ring and the spring are arranged in the atmosphere region.

4. The vacuum valve as claimed in claim 1 ,

wherein

the portion of the supporting ring which is oriented toward the bearing surface is directed toward the inner region, and

the supporting ring and the spring are arranged in the atmosphere region.

5. The vacuum valve according to claim 1 , wherein the inner conical segment of the supporting ring widens with a cone-opening angle of 45° to 135°, in particular 80 to 100°, in the direction of the bearing surface.

6. The vacuum valve according to any claim 1 , wherein the bearing surface is formed on the valve housing.

7. The vacuum valve according to claim 1 ,

wherein

the valve drive is designed for generating a rotary movement,

the shaft feedthrough is designed as a rotary shaft feedthrough, and

the operations of closing and opening or regulating the flow path can be brought about by a rotary movement of the shaft and of the valve closure about the shaft axis.

8. The vacuum valve according to claim 1 , wherein the inner conical segment of the supporting ring widens with a cone-opening angle of 80° to 100° in the direction of the bearing surface.