EP2957772B1 - Vacuum pump - Google Patents

Description

The invention relates to a vacuum pump having a housing, a shaft arranged in the housing, rotatably mounted on roller bearings and at least one arranged in at least one housing part of the housing lubricant reservoir for receiving a lubricant.

The development of vacuum pumps is moving towards vacuum pumps with a high power density and a compact pump housing. Due to the small outer surface of the case, the cooling of the pump housing and of the lubricant via convection presents a particular challenge. While the housing components have temperatures of above 100 ° C usually survive without damage, come to operating equipment, such as serving for the lubrication of the shaft bearings lubricants at elevated temperatures to their limits. These age prematurely and components that are dependent on optimum lubrication properties, such as gear wheels, rolling bearings and also touching seals, have a shortened life and cause shorter service intervals.

A generic vacuum pump is for example from the DE 10 2010 045 880 A1 known. This prior art vacuum pump can be improved to provide more effective cooling of the lubricants.

The prior art ( DE 10 21 530 B ) includes a cooling device for a vacuum rotary piston blower. This belonging to the prior art cooling device consists of a cooling coil, which is arranged in the oil sump of the cooling oil. This cooling coil must be actively cooled by pumping the coolant through the cooling coil. For this purpose, a coolant supply and a pump are required. In addition, a cooling coil requires a relatively large amount of space, so that a compact design according to this prior art is not possible.

Furthermore belongs to the state of the art ( EP 1 967 734 A1 ) a cooling channel, which is arranged in the housing of the pump. Due to the arrangement of the cooling channel in the housing, the housing must be solid in the region of the cooling channel and have a minimum thickness in order to be able to arrange the cooling channel in the housing and at the same time achieve the required stability.

As a result, the housing is larger in size and more expensive overall.

The prior art ( JP-2002-317779A ) further includes a cooling device in which oil is performed between cooling fins and fed into channels. This embodiment is structurally relatively complicated by the formation of the cooling fins and the channels, which precludes a compact design.

The prior art ( JP-2002-115690A ) further includes a cooling device for a vacuum pump. This cooling device has a cooling fin with a hole for the dissipation of heat. Cooling fins have a certain space requirement, so that the space requirement of the entire pump is also increased.

The technical problem underlying the invention is to provide a vacuum pump, which has good cooling properties in a compact design.

This technical problem is solved by a vacuum pump with the features of claim 1.

The vacuum pump according to the invention with a housing, arranged in the housing, rotatably mounted on roller bearings shaft and at least one arranged in at least one housing part of the housing lubricant reservoir for receiving a lubricant, in which at least one provided with a lubricant reservoir housing part of the housing at least one Cooling element is arranged, which is fixed at least on one side in a housing wall of this housing part, is characterized in that the at least one cooling element as a double-sided open, hollow tube is formed, which is arranged substantially perpendicular to the longitudinal axis of the shaft in the housing part, that the housing is fixed in the region of both ends in the housing wall of this housing part.

By the displacement of the actual cooling element in the interior of the housing with an at least one-sided connection to the housing wall and thus also to the environment, it is possible to effect the cooling substantially without an increase in the housing dimensions.

Advantageously, the at least one cooling element projects at least partially into the lubricant reservoir of the relevant housing part in order to achieve effective and direct cooling of the lubricant.

According to the invention it is proposed that the at least one cooling element is designed as a hollow tube open on both sides, which is arranged substantially perpendicularly in the housing part such that the tube is fixed in the region of both ends in the housing wall of this housing part. This hollow pipe, which is open to the environment on both sides, thus acts as a kind of chimney for dissipating the heat from the interior of the housing part.

In the interior of the housing part provided with the at least one hollow tube, heat is released to the air in the hollow tube, the density of which is thereby reduced and rises within the tube up to the upper end opening. The resulting chimney effect thus dissipates heat from the interior of the housing part to the outside and sucks on the lower end of fresh fresh air into the interior of the hollow tube.

Furthermore, it is proposed with the invention that the hollow tube is branched and has more than two end openings, wherein the end of the tube having several end openings advantageously forms the upper end of the tube to allow a faster withdrawal of the heated air.

The heat transfer to the air in the tube inside the housing part can be improved according to a preferred embodiment of the invention in that the tube within the housing part concerned a partial area with an enlarged surface, said portion preferably in the region of the lubricant storage arranged in the part of the tube is arranged. The enlarged surface can be accomplished simply and effectively, for example, by means of heat-conducting ribs arranged on the outside of the pipe or else by increasing the pipe diameter.

By selecting a suitable pipe material, such as a material with high thermal conductivity, the heat transfer to the air in the pipe can be further improved.

To improve the removal of the heated air is proposed with an alternative embodiment of the invention that the upper end of the tube protrudes outwardly beyond the housing wall of the respective housing part.

According to a second advantageous embodiment of the invention, it is proposed that the at least one cooling element is designed as a tube, which protrudes at least on one side outwardly beyond the housing wall of the respective housing part. The housing section projecting pipe section protrudes into the cooler ambient air and thus promotes the heat transfer from the interior of the relevant housing part.

To form this tube is proposed according to a first embodiment that the tube is made of solid material.

Finally, it is proposed with the invention that the projecting at least on one side outwardly beyond the housing wall of the relevant housing part of the pipe in an external coolant flow, preferably an air flow, protruding, whereby the cooling can be significantly improved and accelerated. This external cooling air according to the invention can be used both in the embodiment of the tube made of solid material as well as in the embodiment as filled with a cooling medium hollow tube.

Fig. 1

einen schematischen Längsschnitt durch eine erfindungsgemäße Vakuumpumpe;

Fig. 2

eine vergrößerte Ansicht des Details II, eine erste Ausführungsform darstellend;

Fig. 3

eine Ansicht gemäß Fig. 2, jedoch eine zweite Ausführungsform darstellend;

Fig. 4

eine Ansicht gemäß Fig. 2, jedoch eine dritte Ausführungsform darstellend;

Fig. 5

eine Ansicht gemäß Fig. 2, jedoch eine vierte Ausführungsform darstellend (nicht vom Schutzbereich des Anspruches 1 umfasst) und

Fig. 6

eine Ansicht gemäß Fig. 2, jedoch eine fünfte Ausführungsform darstellend (nicht vom Schutzbereich des Anspruches 1 umfasst).

Further features and advantages of the invention will become apparent from the accompanying drawings, in which various embodiments of a vacuum pump according to the invention are shown by way of example only, without limiting the invention to these embodiments. In the drawings shows:

Fig. 1

a schematic longitudinal section through a vacuum pump according to the invention;

Fig. 2

an enlarged view of the detail II, showing a first embodiment;

Fig. 3

a view according to Fig. 2 but showing a second embodiment;

Fig. 4

a view according to Fig. 2 but showing a third embodiment;

Fig. 5

a view according to Fig. 2 but showing a fourth embodiment (not covered by the scope of claim 1) and

Fig. 6

a view according to Fig. 2 but showing a fifth embodiment (not covered by the scope of claim 1).

Fig. 1 shows in section a vacuum pump 1, the housing 2 has three housing parts 3, 4 and 5, namely a pump chamber 3 and two lubricant chambers 4 and 5, has.

In the housing 2, a shaft 6 is rotatably mounted via rolling bearings 7 horizontally. The shaft 6 is driven by a drive 8, for example an asynchronous motor, which is coupled to the shaft 6 via a magnetic coupling 9. On the the pumping chamber 3 passing through part of the shaft 6, a piston 10 is arranged, which causes the pumping effect during rotation of the shaft 6 and sucks via a suction port 11 in the pumping chamber 3 fluid into the pumping chamber 3 and a likewise formed in the pumping chamber 3 ejection opening 12th again discharges from the pump chamber 3.

At the drive 8 opposite end of the shaft 6, a synchronizing gear 13 is provided in the lubricant chamber 4, which is not visible in this representation, also mounted on a shaft second synchronizing gear in engagement that both waves with the same frequency, but opposite direction of rotation move each other.

Both the synchronizing gear 13 and the rolling bearings 7 must be supplied with a lubricant in order to cool them and to avoid increased wear. For this purpose, the two lubricant spaces 4 and 5 have a lubricant reservoir 14 filled with a lubricant. In the lubricant reservoir 14 dip on the shaft 6 arranged centrifugal discs 15, which distribute the lubricant in the entire lubricant chambers 4 and 5 and in particular the rolling bearings 7 and the synchronizing gear 13 out.

While the components of the housing 2 can withstand temperatures of more than 100 ° C., generally without damage, operating means, such as, for example, the lubricants used for lubricating the roller bearings 7, reach their limits at elevated temperatures. These age prematurely and components which are dependent on optimum lubricating properties, such as synchronizing gears 13, rolling bearings 7 and also touching seals, have a shortened life and cause shorter service intervals.

For this reason, it is necessary to directly or indirectly cool the lubricant spaces 4 and 5 and / or the lubricant in the lubricant reservoirs 14.

In Fig. 2 to 6 By way of example with reference to the lubricant space 4, different embodiments are illustrated, such as the lubricant space 4 and / or the lubricant in the lubricant reservoir 14 can be cooled, without significantly increasing the outer dimensions of the housing 2. The illustrated embodiments are, as shown, also applicable to the lubricant chamber 5 and any other existing lubricant spaces.

It is common to all illustrated embodiments that at least one cooling element 16, which is fixed at least on one side in a housing wall 17 of this housing part 4, 5, is arranged in the at least one housing part 4, 5 of the housing 2 provided with a lubricant reservoir 14. The storage area can also be cooled better.

At the in Fig. 2 illustrated first embodiment, the cooling element 16 is formed as a hollow tube open on both sides 18, which is arranged substantially vertically in the housing part 4, that the tube 18 in the region of both ends in the housing wall 17 of this housing part 4 is fixed. This pipe 18, which is open to the environment on both sides, therefore acts as a kind of chimney for dissipating the heat from the interior of the housing part 4.

In the interior of the housing part 4 provided with the at least one hollow tube 18, heat is released to the air in the tube 18, the density of which is thereby reduced and rises within the tube 18 up to an upper end opening 19. The resulting chimney effect thus dissipates heat from the interior of the housing part 4 to the outside and sucks on the lower end opening 19 fresh cooler air into the interior of the hollow tube 18th

In the Fig. 3 illustrated second embodiment differs from the previously in Fig. 2 illustrated embodiment in that the hollow tube 18 is formed branched and has more than two end openings 19. The end of the tube 18 having a plurality of end openings 19 advantageously forms the upper end of the tube 18 in order to enable a faster withdrawal of the heated air. As an alternative to the illustrated embodiment with two upper end openings 19, it is of course also possible to provide different numbers of end openings 19 at the upper and / or lower end of the tube 18.

At the in Fig. 4 the third embodiment shown in the embodiment of the hollow tube 18 open on both sides of the heat transfer to the air in the tube 18 within the housing part 4 is improved in that the tube 18 within the housing part 4 has a portion 20 with an enlarged surface, said portion 20 is preferably arranged in the region of the arranged in the lubricant reservoir 14 of the pipe 18.

The enlarged surface of the portion 20 of the tube 18 can be, for example, as shown, by arranged on the outside of the tube 18 heat conduction ribs 21 or even simply and effectively accomplish by increasing the pipe diameter.

By selecting a suitable material for the tube 18, such as a material with high thermal conductivity, the heat transfer to the air in the tube 18 can continue to improve in all the embodiments described above.

In the in the Fig. 5 and 6 illustrated embodiments, the at least one cooling element 16 is designed as a tube 22, 23 which protrudes at least on one side outwardly beyond the housing wall 17 of the relevant housing part 4.

According to the in Fig. 5 illustrated fourth embodiment, the tube 22 made of solid material, preferably a material with high thermal conductivity. In this embodiment, the heat transfer takes place purely by heat conduction to the cooler environment outside the housing. 2

At the in Fig. 6 illustrated fifth embodiment, the tube 23 is formed as a hollow tube 23 closed on both sides, in the interior of which a cooling medium is enclosed. Also in this embodiment, the tube 23 is preferably made of a material with high thermal conductivity.

The cooling medium is advantageously designed so that the volume of the cooling medium in the liquid state is less than the inner volume of the tube 23 and that the cooling medium during heating at least partially into the gas phase can be transferred.

Due to the operating temperature within the housing part 4 to be cooled and in particular within the lubricant reservoir 14, the cooling medium located in the hollow tube 23 is partially or completely transferred to the gas phase. This resulting gas rises within the tube 23 and is cooled in the region of a tube projection 24 through the housing wall 17 by the lower ambient temperature outside the housing 2 by heat emission to the environment, whereby the gas is transferred back into the liquid phase and within the tube 23 again runs down into the part of the tube 23 which is arranged in the interior of the housing part 4.

In order to ensure the rising of the gas phase and the reflux of the condensed cooling medium, the filled with the cooling medium hollow tube 23 is advantageously arranged substantially perpendicularly in the respective housing part 4.

The projecting at least one side outwardly beyond the housing wall 17 of the relevant housing part 4 pipe projection 24 preferably projects into an external coolant flow, for example, by a fan (not shown) generated air flow in, whereby the cooling can be significantly improved and accelerated. This external cooling air can be used both in the embodiment of the tube 22 made of solid material as well as in the configuration of the tube 23 as filled with a cooling medium hollow tube.

Although in all figures, only one designed as a tube 18, 22, 23 cooling element 16 is shown, each lubricant space 4, 5 different numbers than tubes 18, 22, 23 formed cooling elements 16 are arranged. By an adapted placement density of the cooling elements 16, the temperature profile can be adjusted.

A vacuum pump 1 designed as described above is characterized in that the cooling of the lubricant reservoir 14 and / or the lubricant spaces 4, 5 and / or other areas such as storage areas or the like is performed by cooling elements 16 substantially inside the lubricant spaces 4, 5 are arranged, whereby the outer dimensions of the vacuum pump - if at all - increase only slightly.

reference numerals

1

vacuum pump

2

casing

3

Housing part / pump chamber

4

Housing part / lubricant chamber

5

Housing part / lubricant chamber

6

wave

7

roller bearing

8th

drive

9

magnetic coupling

10

piston

11

suction

12

discharging port

13

timing gear

14

lubricant reservoir

15

slinger

16

cooling element

17

housing wall

18

Tube (open, hollow)

19

end opening

20

subregion

21

heat conduction

22

Tube (solid material)

23

Pipe (closed, hollow)

24

Pipe supernatant

Claims (8)

1. A vacuum pump with a housing, a shaft arranged in the housing and rotatably mounted by means of roller bearings as well as at least one lubricant reservoir for accommodating lubricant in at least one housing part of the housing, wherein there is arranged in the at least one housing part (4, 5) of the housing (2) provided with the lubricant reservoir (14) at least one cooling element (16), which is fixed at least at one end in a housing wall (17) of this housing part (4, 5),
   characterised in that the at least one cooling element (16) is formed as a hollow tube (18) open at both ends that is arranged in the housing part (4, 5) substantially perpendicular to a longitudinal axis of the shaft (6) such that the tube (18) is fixed in the region of both ends in the housing wall (17) of this housing part (4, 5).
2. A vacuum pump according to claim 1, characterised in that the at least one cooling element (16) projects at least partly into the lubricant reservoir (14) of the respective housing part (4, 5).
3. A vacuum pump according to claim 1, characterised in that the hollow tube (18) is branched and has at least two end openings (19).
4. A vacuum pump according to claim 3, characterised in that the end of the tube (18) having the at least two end openings (19) forms the upper end of the tube (18).
5. A vacuum pump according to any one of claims 1, 3 or 4, characterised in that the tube (18) has a partial region (20) with an enlarged surface area within the respective housing part (4, 5), wherein said partial region (20) is preferably arranged in the region of the part of the tube (18) arranged in the lubricant reservoir (14).
6. A vacuum pump according to claim 1 or 2, characterised in that the at least one cooling element (16) is formed as a tube (22, 23) which projects at least at one end outwardly beyond the housing wall (17) of the respective housing part (4, 5).
7. A vacuum pump according to claim 6, characterised in that the tube (22) consists of solid material.
8. A vacuum pump according to either of claims 6 or 7, characterised in that the part of the tube (22, 23) projecting at one end outwardly beyond the housing wall (17) of the respective housing part (4, 5) is formed projecting into an external coolant flow, preferably an air stream.

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