The present invention relates to a vacuum pump for connecting to a vacuum apparatus and a vacuum system com prising a vacuum apparatus and such a vacuum pump.

Vacuum pum ps known in the art comprise a housing wherein a rotor assembly is disposed within the housing and rotated by an electric m otor. The rotor as sem bly com prises at least one rotor element interacting with a stator, wherein the stator is connected to the housing. Further, the housing com prises an inlet and an outlet, wherein due to interaction of the rotor element with the stator elem ent upon rotation of the rotor assembly a gaseous m edium is conveyed from the inlet to the outlet.

The majority of known vacuum pumps comprise a flange directly connected to the outer most end of the inlet side of the vacuum pum p. Alternatively, so called cartridge pum ps are known, wherein the flange is arranged on the op posite side to the inlet at the pum p base, wherein the vacuum pum p is almost com pletely inserted into a vacuum apparatus. With the flange the vacuum pum p is connected to a vacuum apparatus.

However, in both possibilities the axial position of the vacuum pump with re spect to the vacuum apparatus is fixed. The known vacuum pum ps do not provide any freedom in design and simply provide the choice whether the pump is completely inserted into the vacuum apparatus or externally attached to it.

I n particular, for portable vacuum apparatus such as point of use mass spec trom eter system s, the size of the vacuum apparatus needs to be sm all requir ing m ore degrees of freedom regarding the position of the vacuum pum p with respect to the vacuum apparatus.

I t is a subject of the present application to provide a vacuum pump providing the possibility for a small and com pact design. The technical problem is solved by a vacuum pum p in accordance to claim 1 as well as a vacuum system in accordance to claim 1 1 .

The vacuum pum p in accordance to the present invention for connecting to a vacuum apparatus com prises a housing having a first end defining an inlet and a second end opposite to the first end. I n particular, in the housing a rotor assembly is disposed comprising at least one rotor element wherein the rotor assembly is rotated by an electric m otor. Further, the rotor elem ent is inter acting with at least one stator element connected to the housing in order to convey a gaseous m edium from the inlet to an outlet.

Further, in accordance to the invention the vacuum pump com prises a collar to be connected to a vacuum apparatus. I n particular, the collar is directly connected to the vacuum apparatus. The housing com prises at least one posi tioning elem ent and also the collar comprising at least one positioning element, wherein the positioning elem ent of the housing engages the positioning ele m ent of the collar in order to define an axial position of the housing relative to the collar. This may provide the advantage that by tayloring the position of at least one positioning element, the axial position of the vacuum pum p with re spect to the collar can be adj usted. Since the collar is in particular directly connected to the vacuum apparatus, as a consequence also the axial position of the vacuum pum p with respect to a vacuum apparatus can be adj usted ac cordingly.

Preferably the positioning element of the housing is arranged at the first end of the housing. However, the m ore the positioning element is shifted towards the second end of the housing, the m ore the vacuum pum p is inserted into the vacuum apparatus. I n particular, the positioning element is not arranged di rectly at the first end and also not arranged directly at the second end of the housing, but spaced apart from the first end and the second end which may provide the desired degree of freedom in design of the axial positon of the vacuum pump with respect to the vacuum apparatus. Preferably the housing comprises more than one positioning elem ent. The po sitioning elements are then distributed along an axial direction of the pump wherein each positioning elem ent is spaced apart from the directly adjacent positioning elem ents. Since by the positioning elements the axial position of the vacuum pum p is defined providing m ore than one positioning elem ent at the housing of the vacuum pump, this may have the advantage that with one housing different axial positions can be realized without the necessity to rebuild or reconstruct the housing for each individual application of the vacuum pum p. Additionally or alternatively, the collar comprises m ore than one positioning elem ent distributed along an axial direction of the collar in order to define dif ferent axial positions in which the housing can be placed with respect to the collar, i. e. the vacuum apparatus. Preferably the positioning elem ents of the collar are also separated from each other wherein more preferably the separa tion of the positioning elem ents of the collar are identical to the separation of the positioning elem ents of the housing, in particular if both the housing and the collar com prise more than one positioning element. However, it is also possible to have different separations between the positioning elem ents of the housing and the collar. Different separation between positioning elem ents in the collar and positioning elem ents in the housing provides more relative posi tioning options than sam e spacing. Additionally or alternatively also the num ber of positioning elem ents of the collar and/or the housing can be equal or different.

This m ay provide the advantage that either by the positioning elem ents of the housing or the positioning elem ents of the collar, different axial positions of the vacuum pump with respect to the vacuum apparatus are feasible with one vacuum pum p without the necessity to rebuild or reconstruct for each applica tion.

Preferably the num ber of positioning elem ents of the housing and the num ber of positioning elements of the collar are identical. Alternatively the number of positioning elem ents of the housing and the number of positioning elem ents of the collar are different. More preferably one of the num ber of positioning ele m ents of the housing or the num ber of positioning elem ents of the collar is one while the other is larger than one.

Preferably the positioning elem ent is a circumferential groove. I n particular, the circumferential groove is arranged at an outer surface of the housing and/or a radially inner surface of the collar. I n particular the groove need not to be closed on all three sides but can also be open at one side. Thus, the groove can be built as abutm ent edge. The vacuum pump further com prises a snap ring, which is disposed in the groove of the housing and the groove of the housing sim ultaneously for engagement of the respective positioning elements. Thus, the axial position is defined by the position of the circumferential grooves of the housing and the collar, wherein the axial position is fixed by the snap ring. Further, the apparatus may com prise a face opposing the pump inlet face to further define the axial position. I n particular, if a snap ring is em ployed the groove can be built as abutment edge. Then, assembling is perform ed by ad vancing the vacuum pum p until the snap ring abuts against the abutm ent edge form ed by the groove of the collar. This m ay provide the advantage that if the axial position of the vacuum pum p with respect to the vacuum apparatus needs to be adapted, several positioning elem ents are provided at the housing and/or the collar, the snap ring will be arranged in another pair of opposing grooves of the housing and the collar.

Preferably, the collar comprises at least one set and preferably more than one set of through holes for receiving a screw for connecting the collar to a vacuum apparatus. Thus, each set of through holes may be adapted to a specific con figuration of vacuum apparatus and its individual fastening configurations. Thus, it m ay be possible that the collar can be connected to a larger number of different vacuum apparatus without the necessity to reconstruct or redesign the collar for each vacuum apparatus individually. I n particular, one specific through hole m ight belong to more than one set, wherein each set differs at least by one through hole to cover different fastening configurations of different vacuum apparatus. Preferably the vacuum pum p com prises a centering ring arranged at the first end between the housing and the vacuum apparatus. The centering ring m ain tains a centered position of the vacuum pump with respect to the vacuum ap paratus. Preferably, the centering ring has a circular cross-section. However, alternatively the centering ring may also have any other cross-section such as elliptic, rectangular or any other polygonal form in dependence on the form of the inlet of the vacuum pump and/or the port of the vacuum apparatus.

Preferably the centering ring is in direct contact with both the housing and the vacuum apparatus in order to provide a defined centered position.

Preferably the centering ring com prises a first radial abutment face wherein the first abutment face directly abuts against the housing to define a center position. I n particular, the first abutm ent face abuts against a radial surface of the housing.

Preferably the centering ring com prises a second abutment face that directly abuts against a vacuum apparatus and in particular to a radial surface of the vacuum apparatus to maintain a centered position between the vacuum pump and the vacuum apparatus.

Preferably the radius of the first radial abutm ent face is different than the ra dius of the second radial abutment face. Thus, the diameter of the connection port of the vacuum apparatus can be adapted to the diameter of the inlet of the vacuum pump. This may provide the advantage that the centering ring m ay compensate for different inlet diameter of respective vacuum pum ps and/or vacuum apparatus.

Preferably the centering ring m ay be provided in different lengths along the axial direction. Thus, for one vacuum pum p to be connected to a certain vac uum apparatus the axial position can be adapted without any redesign of the vacuum pump. Further, it is subject of the present invention to provide a vacuum system com prising a vacuum pump as previously described and a vacuum apparatus. Therein the vacuum apparatus might be any vessel, spectrometer or apparatus that requires the existence of a certain vacuum.

Preferably a sealing element is placed between the first end of the vacuum pump and the vacuum apparatus in order to provide a vacuum tight seal of the vacuum pump to the vacuum apparatus.

Specific embodiments of the present application will be described in the follow ing with reference to the accompanied drawing.

The figures show:

Figure 1 an explosion drawing of the vacuum pump in accordance to the present invention,

Figure 2 a detailed view of the vacuum pump connected to a vacuum apparatus,

Figure 3a-3c different configurations of the vacuum system, and

Figure 4 a details view of another embodiment of the positioning ele ments.

The vacuum pump 10 comprises a housing 12 with an inlet 14 arranged at a first end 16 of the housing 12 and an outlet 18 arranged at a second end 20 of the housing 12. At the outer surface 22 of the housing 12 three positioning elements are built as grooves 24a, 24b, 24c. Further, a centering ring 26 is arranged at the first end 16 of the housing 12. The centering ring 26 comprises a first radial abutment face 28 (figure 2) and a second radial abutment face 30, wherein the first abutment face 28 is in direct contact with the housing 12 of the vacuum pum p 10 and the second abutment face 30 is in direct contact with an abutment face of the vacuum apparatus 32. Thus, by the centering ring 26 a centered position of the vacuum pump 10 with respect to the vacuum apparatus 32 is m aintained.

Different distances between the housing 12 of the vacuum pump 10 and the vacuum apparatus 32 can be com pensated by different centering rings 26 which have respectively different length along the axial direction of the pump in correspondence to the housing 12 of the vacuum pum p 10 and the vacuum apparatus 32. Thus, even for the sam e vacuum pump 10 and the sam e vacuum apparatus 32 different axial positions can be chosen with selecting different centering rings having different length along the axial direction of the vacuum pump.

Further, the vacuum pump com prises a collar 34 wherein the collar 34 com prises in the example of figure 1 four through holes 36 to receive screws 38. However, the number and positions of the through holes and screws are not lim ited. I n particular, the collar 34 m ay com prise m ore than one set of through holes 36 to be connected to different fastening configurations of different vac uum apparatuses 32. By the screws 32 the collar 34 is connected to the vac uum apparatus 32. The collar 34 com prises a groove 40 as positioning elem ent. I n particular the groove 40 of the collar need not to be closed on all three sides but can be also open at one side towards the inlet of the vacuum pum p 10. Thus, the groove can be built as abutment edge. The groove 40 of the collar 34 is engaged with one of the grooves 24a, 24b, 24c of the housing 12 by a snap ring 42 in order to define the axial position of the vacuum pump 1 0 with respect to the vacuum apparatus 32. Assem bling is performed by advancing the vacuum pum p 10 into the collar 34 until the snap ring 42 abuts against the abutm ent edge 46, 48 formed by the groove 40.

As shown in figure 2, the snap ring 42 is placed sim ultaneously in the groove 40 of the collar 34 and the groove 24a of the housing 12. I f the collar 34 com prises m ore than one positioning elem ent, as shown in Fig. 4, then a first positioning elem ent built by a first groove 40 has a first diameter and the second positioning elem ent built by a second groove 45 has a second diameter. Therein, the first diam eter is smaller than the second diam eter. I n particular, if m ore than two positioning elements are employed by the collar 34 then the diam eter increases from one groove to the next in a direction from the second end 20 towards the first end 16. Of course, also the positing ele m ents in the housing 12 m ay have different diam eters alternatively or addi tionally. Preferably, the snap ring 42 then m ight have a different thickness in the radial direction to compensate for the different diam eters of the positioning elem ents. This m ay have the advantage that upon inserting the vacuum pum p into the collar 34, due to the decreasing diameter along the inserting direction, the respective snap ring 42 can be received by the respective groove 40, 45 to attach the vacuum pum p 10 to the collar 34. Hereby in particular the groove 40, 45 comprises an open side form ing an abutment edge 46, 48 facing against the inserting direction the snap ring 42 abuts against the abutm ent edge 46, 48 formed by the respective groove 40, 45 of the collar 34.

Due to the collar 34 with the screws 38, the vacuum pum p 10 is fixed to the vacuum apparatus 32 wherein the axial position of the vacuum 10 with respect to the vacuum apparatus 32 is defined by the position of the respective grooves 24a, 24b, 24c and 40. The centered position between the vacuum pum p 10 and the vacuum apparatus 32 is maintained by the centering ring 26 as de scribe above. Further, between the housing 12 of the vacuum pump 1 0 and the vacuum apparatus 32 a vacuum tight seal 44 is arranged to seal and m ain tain the vacuum in the vacuum apparatus and the vacuum pum p.

As shown, the housing 12 of the vacuum pump 10 com prises in the example of the figures three positioning elem ents built as grooves 24a, 24b, 24c. Thereby the num ber of the positioning elements and also the position of the positioning elem ents with respect to the housing 12 of the vacuum pump are not lim ited. Thus, a larger or smaller num ber of positioning elem ents can be em ployed and also the position of the positioning elements itself can be shifted along the axial axis of the vacuum pum p 10 for example towards the second end 20. However, if the groove 40 of the collar 34 is engaged with a groove 24a, 24b, 24c of the housing 12, the axial position of the vacuum pum p 12 with respect to different vacuum apparatus can be adapted providing a degree of freedom in design of the vacuum system . As shown in figures 3a - 3c pro truding of the vacuum pum p 10 from three exem plified vacuum apparatus 32, as denoted by the lengths L1 to L3, can be adapted by using different position ing elem ents, i.e. grooves 24a, 24b, 24c of the housing 12. Thus, the housing 12 of the vacuum pump provides the possibility to adapt the axial position of the vacuum pum p with respect to the vacuum apparatus in particular for different vacuum apparatus without the necessity to redesign or reconstruct the vacuum pump. Thus, one single pump can be provided for sev eral different applications at once providing a high degree of freedom in the design of the respective vacuum system s and facilitate a com pact and optimal design of the respective vacuum system in particular for portable vacuum ap plication such as point of use m ass spectrom eter systems.

Reference n um bers:

10 vacuum pum p

12 housing

14 inlet

16 first end

18 outlet

20 second end

22 outer surface

24a, 24b, 24c grooves

26 centering ring

28 first radial abutm ent face

30 second radial abutm ent face

32 vacuum apparatus

34 collar

36 through holes

38 screws

40 groove

42 snap ring

44 seal

45 second groove

46, 48 abutment edge