VACUUM PUMP

Abstract

The invention relates to a vacuum pump having a cup-shaped housing, a rotor, eccentrically mounted for rotation in the housing, at least one blade mounted in or on the rotor, and a housing cover closing the cup-shaped housing, wherein the rotor has a rotor shaft that passes through the cup-shaped housing and by which the rotor is driven, wherein the rotor shaft is sealed by means of a seal in the housing.

Description

The invention relates to a vacuum pump having a cup-shaped housing, a rotor eccentrically mounted for rotation in the housing, at least one blade mounted in or on the rotor, and a housing cover closing the housing, wherein the rotor has a rotor shaft, which passes through the cup-shaped housing and by which the rotor is driven.

Vacuum pumps having such a configuration are known and typically include a housing made of metal, in which a rotor is rotatably supported via its rotor shaft and in which the work chambers are formed. The pump compartment is sealed to the atmosphere by pressure oil lubrication. The rotor shaft is caused to rotate for example by the engine of a motor vehicle, in particular by the camshaft thereof. At low rotational speed of the shaft, the bearing is insufficiently supplied with oil by the intermittent lubrication at negative pressure in the pump compartment. As a result of the pressure difference, oil flows into the pump compartment and the rotation speed of the shaft is too low to establish sufficient lubrication of the bearing. The mixed friction causes an increased torque.

The invention is therefore based on the object to provide a vacuum pump in which the torque is decreased in this state, i.e. at low rotation speeds.

This object is solved with a vacuum pump of the aforementioned type in that the rotor shaft is sealed by a seal in the housing.

In view of the in particular radial seal, the bearing gap is sealed to the outside from the atmosphere so that the bearing is sufficiently supplied with oil and in the evacuated state reduces the torque especially in the case of idling rotation speed of the engine. The solution according to the invention can be used in vacuum pumps in particular with an intermittent lubrication.

For optimal arrangement of the seal and for providing a sufficient sealing surface, the housing has a housing attachment. for receiving the rotor shaft.

According to an exemplary embodiment, the drive opening in the housing attachment to receive the rotor shaft forms the sealing surface for the seal. The seal is seated hereby on the rotor shaft. In particular, the rotor shaft has a circumferential groove for receiving the seal.

According to preferred exemplary embodiments, the seal is a radial seal, in particular an O-ring, a radial molded seal ring, a shaft seal ring, or a labyrinth seal.

In the case of a labyrinth seal, the drive opening is configured in the region of its free end as a stepped bore and is tapered.

Further advantages, features and details of the invention are set forth from the sub-claims as well as in the following description in which particularly preferred exemplary embodiments are described in detail with reference to the drawing. The features shown in the drawing and mentioned in the description and the claims can be relevant individually or in any combination.

In the drawing, it is shown in:

FIG. 1 a plan view of a vacuum pump with the housing being opened;

FIG. 2 a section II-II according to FIG. 1;

In FIG. 1, reference sign 10 generally designates a vacuum pump in which the housing 12 is shown without housing cover. The housing 12 has a suction port 14, which feeds into an interior space 16. Located in this interior space 16 is a rotor which is generally designated with 18 and in which at least one blade (not shown) is supported for movement in orthogonal relation to the rotation axis 22. The rotor 18 has a rotor shaft 22 and a rotor housing 24, which is only shown as outline and which inter alia is provided to support the at least one blade. The rotor shaft 22 extends through the housing 12, in particular through a bottom 26 of the interior space 18 via a drive opening 28 and protrudes with a rectangular section 30 on the rear side of the housing 12 out of a housing attachment 32. The rotor 18 is rotated via the rectangular section 30, (by means of a not shown drive, e.g. by means of the camshaft of a motor).

The rotor shaft 22 is provided with a seal 34, so that neither lubricant can leak out nor air and/or dirt can enter the interior space 16. In the exemplary embodiment of FIG. 2, this seal 34 is configured as O-ring 36 and lies in a circumferential groove 38 on the rotor shaft. The inner circumferential surface of the drive opening 28 forms hereby the running and sealing surface for the O-ring.

FIGS. 3 and 4 show a second embodiment of the invention in which the seal 34 is configured as labyrinth seal 40. The latter is formed by a stepped bore section 42 of the drive opening 28, which stepped bore section 42 is disposed at the free outer end of the drive opening 28, as shown in FIG. 4, which shows an enlarged detail IV according to FIG. 3. The rotor shaft 22 is also stepped at its free end so that it forms a stepped ring gap 44 together with the stepped bore section 42.

Claims

1-7. (canceled)

8. A vacuum pump, comprising:

a cup-shaped housing;

a rotor eccentrically mounted for rotation in the housing and having a rotor shaft which traverses the cup-shaped housing and drives the rotor;

at least one blade mounted on or in the rotor;

a housing cover to close the cup-shaped housing, and

a labyrinth seal to seal the rotor shaft in the housing.

9. The vacuum pump of claim 8, wherein the housing has a housing attachment for receiving the rotor shaft.

10. The vacuum pump of claim 9, wherein the housing attachment has a drive opening for receiving the rotor shaft, said drive opening forming a sealing surface for the labyrinth seal.

11. The vacuum pump of claim 8, wherein the labyrinth seal is arranged on the rotor shaft.

12. The vacuum pump of claim 8, wherein the rotor shaft is provided with a circumferential groove for receiving the labyrinth seal.

13. The Vacuum pump of claim 10, wherein the drive opening is configured in a region of a free end thereof as a stepped bore and is tapered.