EP3536961B1 - Sealing element vacuum pump - Google Patents

Description

The invention relates to a rotary pump, in particular a vacuum pump for a motor vehicle, with a delivery chamber which has an inlet on a low-pressure side and an outlet on a high-pressure side, with at least one rotor which is arranged in the delivery chamber and delivers a fluid from the inlet into the delivery chamber to the outlet from the delivery chamber, and with a drive shaft which is drive-connected to the rotor.

It is an object of the invention to improve the rotary pump.

One aspect of the invention relates to a rotary pump, in particular a vacuum pump, for example a vacuum pump for a motor vehicle, according to independent claim 1. In addition to the further features defined in this claim, this pump has a delivery chamber which has an inlet on a low-pressure side and an outlet on a high-pressure side, at least one rotor which is arranged in the delivery chamber and delivers a fluid from the inlet into the delivery chamber to the outlet from the delivery chamber, and a drive shaft which is connected to the rotor in terms of drive technology. The rotary pump also has a housing part which at least axially delimits the delivery chamber. To seal the delivery chamber, the rotary pump comprises at least one sealing element which forms a radial sealing gap with the housing part in a sealing region. According to the invention, the sealing element and the housing part together also form an axial gap. According to the invention, the axial gap is larger than the radial sealing gap.

The terms "axial" and "radial" are related to the axis of rotation of the drive shaft and/or the rotor, so that the term "axial" refers to a direction that runs parallel or coaxial to the axis of rotation. Furthermore, the term "radial" refers to a direction that runs perpendicular to the axis of rotation. A "radial extension" is to be understood as an extension along or parallel to a radial direction. An "axial extension" is to be understood as an extension along or parallel to an axial direction.

The documents EN 20 2009 010890 U1 , EN 10 2015 216104 B3 , US 3 565 558 A , WO 2016/150505 A1 , US 1 719 135 A show designs of rotary pumps with a basic structure similar to the present case. The rotary pump from the latter document shows a bearing as an axial extension of a conveying element carrier, but no sealing element with sealing gaps.

According to the invention, the rotor has a conveying element carrier with at least one rotor slot and at least one conveying element guided axially and radially in the rotor slot, which divides the conveying space into at least two conveying cells. The conveying element carrier is advantageously formed in one piece with the drive shaft.

The at least one sealing element is connected to the drive shaft and the conveyor element carrier in a displacement- and rotation-proof manner. Preferably, the at least one sealing element is formed in one piece by the drive shaft and the conveyor element carrier. The term "one piece" is to be understood in particular as formed in one piece, such as by production from a cast, in a sintering process and/or by production in a single or multi-component injection process or advantageously from a single blank. The sealing element is advantageously formed from the material of the drive shaft and/or the rotor, in particular the conveyor element carrier. The at least one sealing element is preferably formed from a blank or from a material, for example a metal powder in a sintering process or a plastic or metal in an injection molding process, together with the rotor, in particular the conveyor element carrier, or with the drive shaft or with the rotor, in particular the conveyor element carrier, and the drive shaft. In principle, the sealing element can be connected in a material-locking manner to the drive shaft and/or the rotor, in particular the conveyor element carrier, for example by a welding process, an adhesive process, an injection-molding process or the like. Furthermore, it is fundamentally conceivable that the sealing element is connected in a force-fitting and/or form-fitting manner to the drive shaft and/or the rotor, in particular the conveying element carrier, for example by pressing on, toothing or the like.

The drive shaft is preferably mounted in the housing part in at least one bearing area, in particular in a plain bearing area. The bearing area is advantageously designed as a plain bearing area. In the bearing area, an outer peripheral surface of the drive shaft can form a radial bearing gap with an inner peripheral surface of an opening or bore in the housing part, which serves, for example, to lubricate the bearing area. A mean distance between the outer peripheral surface of the drive shaft and the Inner circumferential surface of the opening in the housing part is smaller than an average dimension of the radial sealing gap that the sealing element forms with the housing part. This means that the radial bearing gap is smaller or narrower in the radial direction than the radial sealing gap that the Sealing element is formed. The sealing element is preferably arranged without contact with the housing part. The radially directed outer circumferential surface of the sealing element preferably has no contact with the housing part. Preferably, there is no radial and/or axial guidance of the sealing element in the housing part.

An axial extension of the bearing area or the radial bearing gap is at least twice as large, advantageously at least three times as large and particularly advantageously at least four times as large as an axial extension of the sealing area or the radial sealing gap.

Preferably, the bearing area (and thus the radial bearing gap) and the sealing area (and thus the radial sealing gap) are formed completely outside the delivery chamber of the rotary pump. The radial sealing gap can extend to an axial end face of the delivery chamber. Preferably, the radial sealing gap is formed in the axial direction of the rotary pump between the delivery chamber and the radial bearing gap. The axial gap between the sealing element and the housing part is preferably arranged axially between the radial sealing gap and the radial bearing gap.

The drive shaft is preferably mounted in the housing part in at least two bearing areas that are axially spaced apart from one another, in particular in a plain bearing. The radial bearing gap in the bearing areas is preferably smaller in the radial direction than the radial sealing gap. The axial extent of the bearing areas is advantageously at least twice as large, advantageously at least three times as large and particularly advantageously at least four times as large as the axial extent of the radial sealing gap.

The sealing element seals the rotary pump radially on an axial end face so that no or as little fluid as possible can escape from the pumping chamber. The sealing element can form a compensation device that can compensate for manufacturing tolerances along the drive shaft.

According to the invention, the sealing element has an outer diameter that is larger than or equal to an outer diameter of the conveyor element carrier. In principle, it is conceivable, especially if the outer diameter of the sealing element is larger than the outer diameter of the conveyor element carrier, that the Sealing element axially delimits the conveying chamber. According to the invention, the sealing element has an outer diameter that is larger than an outer diameter of the drive shaft, in particular larger than the outer diameter of the drive shaft in the bearing area.

The conveying element carrier preferably has a sealing element on each of its two axial end faces, the axial extent of a bearing region being greater than the sum of the axial extents of the radial sealing gaps of both sealing elements. The rotor can comprise a separate conveying element carrier or form this conveying element carrier, which can be connected to the drive shaft in a form-fitting, force-fitting and/or material-fitting manner such that the rotor or conveying element carrier cannot rotate relative to the drive shaft and preferably cannot be moved linearly relative to the drive shaft either. For this purpose, the rotor or conveying element carrier can be pressed and/or welded or screwed onto the drive shaft, for example. The conveying element carrier can be one-piece with a central opening, or consist of two half-shells that are joined together and, for example, connected to the drive shaft in a form-fitting, force-fitting and/or material-fitting manner. The conveying element carrier forms the at least one sealing element.

Preferably, the rotor forms conveying cells, for example with another rotor or with the help of conveying elements such as vanes, pendulum slides, etc., which convey the fluid from the inlet into the conveying chamber to the outlet from the conveying chamber. The fluid can be compressed in the conveying chamber, for example, if the rotor is arranged eccentrically, or the pressure in the fluid can be increased if the fluid is not very compressible.

The rotor, or at least a part of the rotor, in particular the conveyor element carrier in a rotary pump designed as a vane pump or pendulum slide pump, and the sealing element can be formed in one piece with the drive shaft. This means that the drive shaft can, for example, only form the part of the rotor or the conveying element carrier that can accommodate the vanes, pendulums, etc., which are then guided along an inner peripheral wall of the conveying chamber during operation of the rotary pump and together with the inner peripheral wall form the conveying cells. In this case, the rotor is formed by the conveying element carrier and the said conveying elements, such as vanes or pendulums. The conveying element carrier is preferably formed in one piece with the drive shaft.

If the fluid is not only conveyed during transport in the conveying chamber from the inlet to the outlet, but is simultaneously compressed or the pressure level of the fluid is increased, the rotor can be arranged eccentrically in the conveying chamber, which then leads to conveying cells with a changing volume when the rotor rotates. The housing part that axially limits the conveying chamber, such as a base

and/or a cover which axially closes the conveying chamber forms a surface facing axially towards the conveying chamber. In this surface, a

An immersion pocket can be formed into which the at least one sealing element extends. An axial extent or depth of the immersion pocket is preferably greater than the axial extent of the sealing element, so that, for example, manufacturing tolerances of the drive shaft can be compensated for via the sealing element, since it has an outer diameter that corresponds to or is larger than an outer diameter of the conveyor element carrier.

The immersion pocket is advantageously a recess that is made in the housing part and into which the sealing element extends axially when the rotary pump is assembled or in which it is arranged. The sealing element is advantageously not guided in the immersion pocket. The immersion pocket is arranged in the housing part adjacent to the conveying chamber and in front of the opening that forms the bearing area for the drive shaft, so that a circumferential groove is formed in the housing part that is directly adjacent to the conveying chamber. The immersion pocket is designed to be open axially to the conveying chamber and radially to the drive shaft. The immersion pocket can be cover and/or in the floor of the conveying chamber. An outer diameter of the

The immersion pocket is smaller than an outer diameter of the conveying chamber. The outer diameter of the immersion pocket should preferably be understood here as the distance between two points in the radially outer circumferential surface of the immersion pocket that are opposite one another in relation to a longitudinal center axis of the conveying chamber.

An axial extension of the immersion pocket should in particular be greater than a maximum axial play of the drive shaft, which is determined, for example, by manufacturing and/or assembly tolerances of the housing and/or the connection between the rotor and the drive shaft. The axial extension of the immersion pocket is advantageously at least twice and particularly advantageously at least three times as large as the axial extension of the bearing area.

The housing of the rotary pump can, for example, have a cover that closes off the delivery chamber on a first axial side or a first axial end, and a base that is arranged axially opposite the cover in relation to the delivery chamber and closes off a second axial side of the delivery chamber. The base can be formed as a unit with the housing, so that the delivery chamber is pot-shaped and can be closed with the cover.

As already mentioned, the immersion pocket can be incorporated in the cover and/or in the base, which axially delimit the conveying chamber. If each axial end comprises an immersion pocket, the immersion pockets in the base and cover and the sealing elements protruding into them or arranged on them can have identical or different diameters and identical or different axial extensions. It is preferred if in this case both sealing elements are identical.

The radial sealing gap, which is formed by a radial outer circumferential surface of the sealing element and a radial inner circumferential surface of the immersion pocket facing the sealing element, can be filled with a fluid, for example, in order to radially seal the conveying chamber. The inflow of the fluid into the immersion pocket can, for example, be a leakage flow along the drive shaft in the bearing gap and/or a fluid, in particular a fluid conveyed by a fluid conveying pump, can be guided directly into the immersion pocket via at least one channel.

The drive shaft can have an axial groove to support the supply of fluid into the immersion pocket. The sealing gap can have the same radial extent or gap thickness over its axial extent, i.e. the radial outer circumferential surface of the sealing element and the radial inner circumferential surface of the immersion pocket run parallel to one another. Alternatively, the sealing gap can have a radial gap thickness that changes over its axial extent, for example it can be wedge-shaped, have areas of decreasing and increasing gap thickness, or have different gap thicknesses in other ways. At least the radial outer circumferential surface of the sealing element can be roughened at least in a circumferential axial partial area or have a profile that can be advantageous for radial sealing.

The drive shaft is mounted in the housing, or in the housing part outside the conveying chamber, in particular in a sliding bearing. The drive shaft has at least one bearing area. The sealing element is preferably arranged axially between a bearing area and the conveying chamber in the immersion pocket. An axial extension of the bearing area of the drive shaft is preferably significantly larger than an axial extension of the sealing element, in particular than an axial extension of the immersion pocket. The axial extension of the bearing area of the drive shaft is advantageously at least twice, particularly advantageously at least three times and very particularly advantageously at least four times as large as the axial extension of the sealing element, in particular as the axial extension of the immersion pocket.

The rotor slot of the conveying element carrier preferably extends axially into the drive shaft, so that the rotor slot axially overlaps the sealing element in the region of the rotor slot. The rotor slot advantageously extends axially out of the conveying chamber at least on one axial side. The rotor slot advantageously extends axially into a bearing region of the drive shaft at least on one axial side. This allows a lubricant and/or sealing agent, in particular a liquid such as oil, to pass from the bearing region of the drive shaft into the conveying chamber, for example to lubricate moving parts of the rotor and/or to seal the conveying cells of the conveying chamber against one another.

The rotor slot may have an axial extent or length that is at least as long as the axial extent or length of the rotor plus the axial extent of the at least one sealing element or the immersion pocket. The axial extent or length of the rotor slot is preferably greater. An axial fit extent or fit length of the rotor is preferably at least as long as the axial extent of the rotor plus a maximum axial play of the drive shaft. The fit extent or fit length here is preferably the area of the rotor slot in which, for example, a blade of the rotor can be moved unhindered transversely to the axis of rotation in the rotor slot, regardless of, for example, an axial play of the drive shaft.

According to the invention, the sealing element is formed as an axial extension of the conveying element carrier, which extends axially from the conveying chamber into the housing part. This extension preferably does not undergo any guidance and/or bearing and/or centering in the housing part. Guidance and/or bearing and/or centering of the drive shaft advantageously only takes place in the at least one bearing area and not in the sealing area provided as an extension by the at least one sealing element.

A second aspect of the invention relates to a pump unit with a first rotary pump with a delivery chamber in which at least one rotor is arranged, which delivers a first fluid from an inlet into the delivery chamber on a low-pressure side of the first rotary pump to an outlet from the delivery chamber on a high-pressure side of the first rotary pump, with a second rotary pump with a delivery chamber in which at least one rotor is arranged, which delivers a second fluid from an inlet into the delivery chamber on a low-pressure side of the second rotary pump to an outlet from the delivery chamber on a high-pressure side of the second rotary pump, and with a drive shaft for driving both rotary pumps, wherein the rotor of the first rotary pump and the rotor of the second rotary pump are connected to the drive shaft in an axially displaceable and rotationally fixed manner.

The drive shaft is a one-piece drive shaft with a continuous axis of rotation. This means that the drive shaft extends through the delivery chamber of the first rotary pump and through the delivery chamber of the second rotary pump, wherein preferably at least one axial end of the drive shaft can extend out of a housing of the pump unit in order to be connected to a drive. The drive shaft can form at least part of the rotor of the first rotary pump and/or part of the rotor of the second rotary pump in one piece. form as was described for the first aspect. At least a part of at least one of the rotors can be pressed onto the rotor shaft or connected to the rotor in another way in a rotationally fixed manner and preferably also in a linear manner in the axial direction so as not to be movable or adjustable, see also the description of the drive shaft for the first aspect. The first fluid and the second fluid are preferably different fluids. The fluid of the first rotary pump, which can be a liquid feed pump, for example, can be a lubricating oil with which the first rotary pump and/or the second rotary pump and/or at least one unit, for example a drive motor, such as an internal combustion engine, a hybrid or electric motor of a motor vehicle, are supplied with lubricating oil. The second fluid of the second rotary pump, which can be a gas pump or vacuum pump, can be a gas which is extracted from a unit, in particular a brake booster of a motor vehicle, for example, to generate a vacuum.

The second rotary pump is a rotary pump according to the first aspect.

In this arrangement, the sealing element or sealing elements can compensate in particular for a manufacturing tolerance in a distance between the rotor of the first rotary pump and the rotor of the second rotary pump, which is introduced into the system or arrangement, for example, by pressing at least one of the rotors, in particular one of the conveying element carriers, onto the drive shaft. In other words, the sealing element engaging in the immersion pocket can form a compensation device in the assembled pump or pump unit, with which an axial play in the system along the drive shaft due to manufacturing tolerances, for example, can be compensated without this eliminating the seal of the conveying chamber.

An immersion pocket can be formed, for example, in a base of the second feed pump, whereby the base generally seals the feed chamber from the environment of the pump unit. Additionally or alternatively, one or more immersion pockets can be formed in at least one cover of the second rotary pump. In the pump arrangement, the cover can be a housing part that Discharge chamber of the first rotary pump from the discharge chamber of the second rotary pump and has an opening through which the drive shaft can pass. In this case, the immersion pocket is formed as a radial widening of the opening in the cover facing the conveying chamber.

The rotor shaft or drive shaft can have a fluid groove in the area of the immersion pocket in the cover and/or base of the rotary pump. The fluid groove can preferably be designed to run all the way around the shaft. For example, fluid can flow from the immersion pocket into the rotor slot via the fluid groove in order to lubricate the moving parts of the rotor and/or to seal the conveying cells of a conveying chamber against one another.

The fluid or liquid conveying pump can in particular be an internal-axis pump, such as a vane pump or a pendulum slide pump.

The gas or vacuum pump can in particular be an internal-axis pump, such as a rotary piston pump, a piston pendulum pump, a vane pump, a pendulum slide pump, an internal gear pump or an internal-axis pump known in the prior art, or an external-axis pump, such as an external gear pump.

The pump unit, which consists of at least one fluid feed pump and at least one vacuum pump, can be attached to an engine, in particular an internal combustion engine of a motor vehicle, for example, or can be intended for attachment to this engine. The drive shaft of the pump unit can be connected to the engine in terms of drive technology, so that the pump unit is driven or controlled or regulated at least temporarily as a function of the engine or a characteristic map with engine-dependent parameters. Alternatively, the pump unit can be driven by its own drive, such as an electric motor.

An embodiment of the invention will now be explained in more detail with reference to figures.

Figur 1:

Pumpeinheit mit Flüssigkeitspumpe und Gaspumpe in einer ersten Schnittansicht.

Figur 2:

vergrößerter Ausschnitt eines Bereichs der Gaspumpe aus Figur 1.

Figur 3:

Pumpeinheit mit Flüssigkeitspumpe und Gaspumpe in einer zweiten Schnittansicht.

Figur 4:

vergrößerter Ausschnitt eines Bereichs der Gaspumpe aus Figur 3.

Figur 5:

Antriebswelle der Pumpeinheit, mit einem Förderelementträger zur Aufnahme von Förderelementen der Flüssigkeitspumpe und einem Förderelementträger der Gaspumpe, in dem ein Förderelement verschieblich angeordnet ist, wobei das Gehäuse der Gaspumpe geschnitten dargestellt ist.

Figur 6:

vergrößerter Ausschnitt der Antriebswelle mit dem Rotor der Gaspumpe der Figur 5.

The figures show in detail:

Figure 1:

Pump unit with liquid pump and gas pump in a first sectional view.

Figure 2:

enlarged section of a section of the gas pump from Figure 1 .

Figure 3:

Pump unit with liquid pump and gas pump in a second sectional view.

Figure 4:

enlarged section of a section of the gas pump from Figure 3 .

Figure 5:

Drive shaft of the pump unit, with a conveying element carrier for receiving conveying elements of the liquid pump and a conveying element carrier of the gas pump, in which a conveying element is movably arranged, wherein the housing of the gas pump is shown in section.

Figure 6:

enlarged section of the drive shaft with the rotor of the gas pump of the Figure 5 .

The Figure 1 shows a longitudinal section through an embodiment of a pump unit according to the invention. The pump unit comprises a first rotary pump 1, which serves as Fluid feed pump, and a second rotary pump 2, which is designed as a vacuum pump. The pump unit can be referred to as a tandem pump. The pump unit is provided for a motor vehicle, wherein the first rotary pump 1 is used to lubricate an internal combustion engine of the motor vehicle, and the second rotary pump 2 is used to provide a vacuum for a brake booster of the motor vehicle.

The rotary pump 1 comprises a delivery chamber 11 in which a rotor 12 is arranged. The rotary pump 2 comprises a delivery chamber 21 in which a rotor 22 is arranged. The rotor 12 and the rotor 22 are connected in terms of drive technology to a common continuous drive shaft 3. The rotors 12, 22 are driven in rotation by the drive shaft 3.

The rotor 12 is arranged completely in the conveying chamber 11. The rotor 12 comprises a conveying element carrier 6 and a plurality of conveying elements which are accommodated in a radially displaceable manner by the conveying element carrier 6. The conveying element carrier 6 has a plurality of rotor slots for displaceably accommodating the conveying elements. The conveying element carrier 6 is connected to the drive shaft 3 in a rotationally fixed and displacement-proof manner. The conveying element carrier 6 is pressed onto the drive shaft 3. The conveying elements are designed as vanes. The first rotary pump 1 is designed as a vane pump.

The rotor 22 is arranged completely in the conveying chamber 21. The rotor 22 comprises a conveying element carrier 5 and a conveying element 4, which is accommodated in a radially displaceable manner by the conveying element carrier 5. For the displaceable accommodation of the conveying element 4, the conveying element carrier 5 has a rotor slot 32, which is in the Figures 3 to 6 clearly shown and described in detail. The rotor slot 32 extends axially into the drive shaft 3. The conveying element carrier 5 is connected to the drive shaft 3 in a rotationally fixed and displacement-proof manner. The conveying element carrier 5 is formed in one piece with the drive shaft 3. The drive shaft 3 forms the conveying element carrier 5 in one piece. The conveying element 4 is designed as a vane. The second rotary pump 2 is designed as a vane pump.

The rotor 12, 22 together with an inner peripheral wall of the respective conveying chamber 11, 21 forms conveying cells in which the fluid, whether liquid or gas, is fed from an inlet into the Conveying chamber 11, 21 to an outlet from this conveying chamber 11, 21 and, with an eccentric arrangement of the rotor 12, 22 in the conveying chamber 11, 21, can be compressed and/or raised to a higher pressure level.

The rotary pumps 1, 2 comprise a common pump housing. The pump housing has the housing parts 13, 14, 23, 24. The two housing parts 13, 23 are combined in one housing part. They are formed by a single housing part. The housing part 24 forms a bottom of the delivery chamber 21 of the second rotary pump 2 with a central opening through which the drive shaft 3 can be connected to a drive (not shown). The housing part 24 closes an axial end face of the delivery chamber 21 on the side facing away from the first rotary pump 1. On the end face facing the first rotary pump 1, the delivery chamber 21 is closed by the housing part 23, which simultaneously forms the housing part 13 for an axial end face of the delivery chamber 11 of the first rotary pump 1 and comprises an opening through which the drive shaft 3 extends from the delivery chamber 21 into the delivery chamber 11. The second axial end face of the conveying chamber 11 is closed by the housing part 14.

The drive shaft 3 is mounted in the pump housing by means of three axially spaced plain bearings. The drive shaft 3 has three axially spaced bearing areas 7, 8, 9. The drive shaft 3 is slide-mounted in the bearing area 9 in the housing part 14, in the bearing area 7 in the common housing part 13, 23 and in the bearing area 8 in the housing part 24. In the bearing areas 7, 8, 9, the outer peripheral surface of the drive shaft 3 and the radially opposite inner peripheral surfaces of the housing parts 14, 13, 23, 24 form a bearing gap S _L . The delivery chamber 11 of the first rotary pump 1 is arranged axially between the bearing area 9 and the bearing area 7. The delivery chamber 21 of the second rotary pump 2 is arranged axially between the bearing area 7 and the bearing area 8.

The second rotary pump 2 comprises two axially spaced sealing elements 26, 27 which extend outside the delivery chamber 21 into immersion pockets 28, 29 which are introduced into the housing part 24 and into the housing part 23. The delivery chamber 21 is arranged axially between the sealing elements 26, 27. The sealing element 26 is arranged axially between the bearing area 7 and the delivery chamber 21. The sealing element 27 is arranged axially between the bearing area 8 and the delivery chamber 21.

The radial outer surfaces of the sealing elements 26, 27 form a radial sealing gap S _D with radial peripheral surfaces of the immersion pockets 28, 29, which is so large in the radial direction that the sealing elements 26, 27 do not receive any radial and/or axial guidance in the immersion pockets 28, 29. The radial sealing gap S _D is larger or has a larger radial extent than the bearing gap S _L . The immersion pockets 28, 29 each have an outer diameter that is larger than an outer diameter of the conveying element carrier 5 of the rotor 22.

The Figure 1 comprises a circularly encircled section X, which in an enlargement in the Figure 2 is shown. The Figure 2 shows section X of the Figure 1 , which shows a section of the second rotary pump 2, with the delivery chamber 21, the delivery element carrier 5 formed by the drive shaft 3 and the delivery element 4, the housing part 24, the housing part 23 and the drive shaft 3. In the housing part 23 and the housing part 24, an immersion pocket 28, 29 is formed which is open to the delivery chamber 21 and into which the sealing elements 26, 27 extend.

The sealing elements 26, 27 are formed in one piece with the conveying element carrier 5 of the rotor 22 and the drive shaft 3. They seal the conveying chamber 21 radially. The sealing elements 26, 27 have the same outer diameter as the conveying element carrier 5. The sealing elements 26, 27 are formed as or by axial extensions of the conveying element carrier 5, which extend axially from the conveying chamber 21 into the immersion pockets 28, 29. The extensions have an outer diameter that is larger than an outer diameter of the drive shaft 3. The extensions extend into the housing parts 23, 24 that axially delimit the conveying chamber 21.

An axial extension of the sealing elements 26, 27 is smaller than the axial extension or depth of the immersion pockets 28, 29, so that an axial play of the drive shaft 3 can be compensated via the sealing elements 26, 27. Preferably, the length difference in the axial direction between the axial depth of the immersion pockets 28, 29 and the axial extension of the sealing elements 26, 27 is greater than a maximum axial play of the drive shaft 3. An axial extension of the radial sealing gap S _D is significantly smaller than an axial extension of the radial bearing gap S _L .

The radial sealing gap So can be supplied with fluid via a leakage flow which flows from the first conveying chamber 11 along the drive shaft 3 to the immersion pocket 28, 29.

Alternatively, the immersion pockets 28, 29 can be supplied with fluid via a channel (not shown) that opens into the immersion pocket 28, 29. The fluid forms a barrier in the radial sealing gap S _D and thus prevents fluid, in this case gas, from escaping from the conveying chamber 21.

The Figure 3 shows another longitudinal section through the pump unit, which in comparison to the Figure 1 the pump unit with respect to a longitudinal axis L or rotation axis of the drive shaft 3 in a view rotated by a quarter turn or by 90°. In the Figure 3 the area of the second rotary pump 2 is marked by a circular cutout Y. The cutout Y is in the Figure 4 to be seen in a magnifying glass view.

The Figure 3 shows nothing other than the Figure 1 , just from a different angle. The first rotary pump 1, the second rotary pump 2 and the drive shaft 3 can be seen. The rotor slot 32 is formed in the drive shaft 3 in the area of the conveying element carrier 5 of the second rotary pump 2, which is formed by the drive shaft 3. The conveying element 4 can move in the rotor slot 3 transversely to the longitudinal axis L in order to form conveying cells together with an inner peripheral wall 25 of the conveying chamber 21, with which the fluid can be conveyed from an inlet into the conveying chamber 21 to an outlet from the conveying chamber 21. An immersion pocket 28, 29 is introduced into each of the immersion pockets 28, 29. A sealing element 26, 27 extends into each of the immersion pockets 28, 29 and radially seals the conveying chamber 21 in the area of the transition from the rotor 22 into the housing part 23 and into the housing part 24. Because the sealing element 26, 27 is dimensioned smaller in the axial direction than the immersion pocket 28, 29, an axial gap _SA is formed between the axial end face of the sealing element 26, 27 facing away from the rotor 22 and the base surface of the immersion pocket 28, 29 facing the rotor 22. As a result, the immersion pockets 28, 29 in conjunction with the sealing elements 26, 27 together form a compensation device with which manufacturing tolerances in the axial direction, which can be introduced into the pump unit, for example when the conveying element carrier 6 of the first rotary pump 1 is pressed onto it, can be compensated.

The Figure 4 shows a magnifying glass view of an area of the Figure 3 , which in particular comprises the rotor slot 32. The rotor slot 32 has an axial extension L _RS and extends axially through the conveyor element carrier 5 of the rotor 22, through both sealing elements 26, 27 into the drive shaft 3. The rotor slot 32 extends axially into the bearing areas 7, 8. The axial extent or axial length L _RS of the rotor slot 32 shown is greater than the axial extent or axial length L _R of the rotor 22 plus the axial extent L _V of the two sealing elements 26, 27 in total. A further dimension is an axial fit extent or fit length L _P , which is smaller than the axial length L _RS of the rotor slot 32, but greater than the axial length L _R of the rotor 22. The axial fit length L _P refers to the area of the rotor slot 32 in which the conveying element 4 can move unhindered, for example without jamming, transversely to the longitudinal axis L of the rotary pump 2, and in which the conveying element 4 is not pressed against one of the housing parts 23, 24 when the rotor slot 32 is shifted in the direction of the longitudinal axis L, for example to compensate for axial play in the drive shaft 3.

A circumferential groove 31 is also formed in the drive shaft 3. The circumferential groove 31 is connected to the corresponding immersion pocket 28, 29 and the corresponding bearing area 7, 8. Furthermore, the groove 31 is connected to the rotor slot 32. The rotor slot 32 extends into the circumferential groove 31. In the exemplary embodiment, the groove 31 is split in two and opens into the rotor slot 32. This allows fluid from the immersion pocket 28, 29 and the bearing area 7, 8 to reach the rotor slot 32, where the fluid can be used, for example, to lubricate the conveying element 4 and to seal the conveying cells in the conveying chamber.

The circumferential groove 31 is particularly suitable for Figures 5 and 6 recognizable. In the Figure 5 the drive shaft 3 of the pump unit is shown uncut. In the Figure 5 The housing parts 23, 24 are also shown in a sectional view. In the Figure 6 is section Z from the Figure 5 shown enlarged.

Claims (12)

1. A rotary pump, preferably a vacuum pump, featuring:

   a delivery space (21) comprising an inlet on a low-pressure side and an outlet on a high-pressure side of the pump (2);

   a rotor (22) which is arranged in the delivery space (21) and delivers a fluid from the inlet into the delivery space (21) to the outlet from the delivery space (21);

   at least one housing part (23, 24) which delineates the delivery space (21) at least axially;

   a sealing element (26, 27); and

   a drive shaft (3) which is connected in drive terms to the rotor (22), wherein

   the rotor (22) comprises: a delivery element support (5) featuring at least one rotor slot (32); and at least one delivery element (4) which is axially and radially guided in the rotor slot (32) and which sub-divides the delivery space (21) into at least two delivery cells,

   the sealing element (26, 27) is formed as an axial extension of the delivery element support (5), which extends axially out of the delivery space (21) into the housing part (23, 24), wherein

   the sealing element (26, 27) and the housing part (23, 24) form an axial gap (G_A) together,

   the at least one sealing element (26, 27) is connected, secured against shifting and rotating, to the drive shaft (3) and the delivery element support (5), and

   the sealing element (26, 27) exhibits an outer diameter which is larger than or equal to an outer diameter of the delivery element support (5),

   characterised in that

   the sealing element (26, 27) forms a radial sealing gap (Gs) with the housing part (23, 24), and

   the axial gap (G_A) is larger than the radial sealing gap (Gs).
2. The rotary pump according to claim 1, characterised in that the sealing element (26, 27) is integrally formed by the drive shaft (3) and the rotor (22).
3. The rotary pump according to any one of the preceding claims, wherein the drive shaft (3) is mounted in at least one bearing region (7, 8) in the housing part (23, 24) and forms a radial bearing gap (G_B) with the housing part (23, 24) in the bearing region (7, 8), wherein the radial bearing gap (G_B) is smaller in the radial direction than the radial sealing gap (Gs).
4. The rotary pump according to any one of the preceding claims, wherein the drive shaft (3) is mounted in at least one bearing region (7, 8) in the housing part (23, 24), wherein the bearing region (7, 8) exhibits an axial extent which is at least twice as large as an axial extent of the radial sealing gap (Gs).
5. The rotary pump according to any one of the preceding claims, wherein an immersion pocket (28, 29) which is axially open towards the delivery space (21) and in which the sealing element (26, 27) is arranged is incorporated in the housing part (23, 24).
6. The rotary pump according to claim 5, wherein the difference in length in the axial direction between an axial depth of the immersion pocket (28, 29) and an axial extent of the sealing element (26, 27) is larger than a maximum axial clearance of the drive shaft (3).
7. The rotary pump according to any one of the preceding claims, wherein the rotor (22) comprises a sealing element (26, 27) on each of its two axial end-facing sides, and the sealing elements (26, 27) exhibit identical or different outer diameters and/or identical or different axial extents (Lv).
8. The rotary pump according to at least claims 4 and 7, wherein the axial extent of the bearing region (7, 8) is larger than the sum of the axial extents of the radial sealing gaps (Gs).
9. The rotary pump according to at least claim 5, wherein the immersion pocket/s (28, 29) is/are supplied with lubricant and/or sealant by an inward flow of a lubricant and/or sealant via the radial bearing gap (G_B) with or without a lubricant and/or sealant groove, or a lubricant and/or sealant supplying bore emerges into the immersion pocket/s (28, 29).
10. The rotary pump according to any one of the preceding claims, wherein the rotor slot (32) exhibits an axial extent (L_RS) which is at least as large as and preferably larger than the axial extent (L_R) of the rotor (22) plus the axial extent (Lv) of the at least one sealing element (26, 27).
11. The rotary pump according to any one of the preceding claims, wherein the rotor slot (32) exhibits an axial fitting extent (L_F) which is at least as large as the axial extent (L_R) of the rotor (22) plus a maximum axial clearance of the drive shaft (3).
12. A pump unit for a motor vehicle, comprising:

    a first rotary pump (1) featuring a delivery space (11) in which at least one rotor (12) is arranged which delivers a fluid from an inlet into the delivery space (11) on a low-pressure side of the first rotary pump (1) to an outlet from the delivery space (11) on a high-pressure side of the first rotary pump (1);

    a second rotary pump (2) according to any one of claims 1 to 11, featuring a delivery space (21) in which at least one rotor (22) is arranged which delivers a fluid from an inlet into the delivery space (21) on a low-pressure side of the second rotary pump (2) to an outlet from the delivery space (21) on a high-pressure side of the second rotary pump (2); and

    a drive shaft (3) for driving the rotary pumps (1, 2), wherein the rotor (12) of the first rotary pump (1) and the rotor (22) of the second rotary pump (2) are connected, secured against axially shifting, to the drive shaft (3).

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