EP2902629B1 - Vacuum pump with lubricant cooler - Google Patents

Description

The invention relates to a vacuum pump with the features of the preamble of claim 1.

From the prior art ( DE 10 2010 045 880 A1 ) Vacuum pumps are known which have a lubricant-lubricated rolling bearing to support waves rotatably. In the case of a plurality of shafts, for example in the case of Roots pumps, the shafts are synchronized by a gear with synchronizing gears, so that pistons connected to the shafts roll over one another with a small gap without contact.

For adequate supply of lubricant is known to provide a lubricant reservoir, in which a centrifugal disk mounted on one of the shafts dips and lubricates lubricant and distributed in the space in which rolling bearings and / or synchronizing gears are arranged.

Vacuum pumps should have ever more compact pump housings high power density. Cooling of the pump housing in general and of the lubricant in particular via convection is a challenge because of the relatively small exterior surface of the housing and despite its ribbing. While housing components generally survive temperatures above 100 ° C. without damage, equipment at elevated temperatures reaches its limits , These resources age prematurely and wear components that depend on optimal lubricant properties. Components such as gear wheels, rolling bearings and also touching seals have a shortened service life. As a result, service intervals are getting shorter.

The prior art ( DE 10 2005 033 084 A1 ) includes an oil-injected compressor with oil temperature control means. According to this prior art, a simple cooling circuit is provided, which supplies the oil from an oil reservoir to a cooling device.

Furthermore belongs to the state of the art ( EP 0 290 663 A1 ) a single- or multi-stage twin-shaft vacuum pump having a coolant circuit consisting of a coolant line, a heat exchanger, a coolant pump and a plurality of cooling lines, which lead into cavities of waves. The entire coolant is passed through the heat exchanger (81). This embodiment has the disadvantage that the flow velocity of the coolant in the coolant circuit significantly slows down is because all the coolant must pass through the heat exchanger. This allows the cooling system to warm up at very high temperatures despite the heat exchanger.

The technical problem underlying the invention is to provide a vacuum pump with which a better cooling of the lubricant is possible.

This technical problem is solved by a vacuum pump having the features according to claim 1.

The vacuum pump according to the invention with a shaft, with a shaft axis, a space for receiving a lubricant filling, at least one arranged on the shaft gear with at least one rolling bearing for rotatably supporting the shaft, with a lubricant pump for transporting the lubricant in a lubricant circuit, wherein the lubricant circuit at least an outlet, wherein the outlet for wetting the at least a gear and / or the at least one rolling bearing is formed with the lubricant, or wherein the outlet is formed as a supply of the lubricant in the lubricant filling, characterized in that in the lubricant circuit at least one branch is provided and that the at least one branch with at least one cooling device for cooling the lubricant is connected and that the lubricant circuit, consisting of the lubricant pump and the lubricant line has a branch, which leads via a lubricant line to a cooling device.

The device according to the invention has the advantage that the lubricant passes through an additional lubricant circuit and / or an additional cooling device for cooling the lubricant and is thus cooled better than in the vacuum pumps belonging to the prior art.

Advantageously, the at least one branch is connected to at least one existing or at least one additional cooling device. It is possible to pass the lubricant through an additional cooling device to achieve a cooling of the lubricant. However, it is also possible to use already existing cooling devices, for example a fan, which cools the housing of the vacuum pump, for cooling the lubricant.

According to an advantageous embodiment of the invention it is provided that the cooling device is formed from a lubricant line with at least one arranged in the lubricant line direction-changing portion. This section can, for example, at least one turn, at least one sheet and / or consist of at least one meandering section. Other embodiments are also possible.

This design of the cooling device increases the surface area of the lubricant line. By increasing the length of the cooling line and the cooling effective surface, the lubricant can be brought to the required temperature depending on the ambient conditions, that is to be cooled.

A further advantageous embodiment of the invention provides to form the cooling device as a hollow body. The lubricant is advantageously injected into the hollow body. It is thus distributed to an inner wall of the hollow body and in this case gives off heat to the housing of the hollow body. The hollow body can be additionally cooled from the outside by means of air or a liquid.

The hollow body may advantageously be spherical or cuboidal or cone-shaped or else formed in another geometrical spatial form.

The hollow body may be formed for example as a double cone or the like.

According to a further advantageous embodiment of the invention, the hollow body is formed from at least two identical parts. As a result, an inexpensive production of the hollow body is ensured.

According to a particularly preferred embodiment of the invention, it is provided to arrange structures for retaining the lubricant in the hollow body. These structures may, for example, be arranged spirally in the hollow body. They are advantageously arranged on the inner wall of the hollow body, so that the lubricant, which is distributed on the inner wall of the hollow body, slows down on the inner wall of the hollow body due to gravity expires and thus remains in contact with the housing wall of the hollow body longer. As a result, an improved heat exchange between the lubricant and the housing of the hollow body is possible.

The structures in the hollow body may be formed, for example, as grooves or protrusions. It is also possible to provide other designs, for example in the form of noses.

According to a further advantageous embodiment, the hollow body has an outlet which is arranged in the direction of gravity of the lubricant.

This embodiment has the advantage that the lubricant leaves the hollow body due to gravity, after it has been injected into the hollow body.

The lubricant is then either returned to the coolant circuit or it is passed directly to the at least one gear and / or the at least one rolling bearing or back into the lubricant reservoir.

Advantageously, the material of the hollow body is designed such that it has a high thermal conductivity, so that the effectiveness of the heat exchange is increased. The oil is injected against the inner surface of the hollow body, cools there and flows back. The hollow body is advantageously mounted at a location above the inlet to the housing of the vacuum pump. The hollow body does not have to be in the immediate vicinity of the lubricant pump.

It is also possible to form the hollow body with a double wall and to allow an additional coolant to flow through between the walls. Particularly advantageously, the parts of the hollow body made of identical parts in order to reduce costs.

The structure in the interior of the hollow body on the one hand has the task of keeping the lubricant longer in the hollow body. At the same time, however, a filter effect also occurs, so that dirt particles present in the lubricant settle in the structures. The hollow body is advantageously cleaned in this case from time to time.

If the parts of the hollow body are made of identical parts, the parts can also be stacked as needed in several layers to be used as a heat exchanger with variable power.

It is also possible to form the hollow body with a plurality of chambers. In the inner chamber, the lubricant is arranged. Through the second enclosed volume cooling water or another cooling medium is performed. Due to the good heat connection, the equipment in the second chamber can be effectively cooled. Compared to the cooling of the entire pump, the power requirement is reduced. The active cooling of the equipment can be retrofitted with minimal effort to meet changed operating parameters or to compensate for previously misjudged conditions of novel processes.

According to a further advantageous embodiment of the invention, the cooling device is formed from at least one component with a heat exchanger function.

According to a particularly preferred embodiment of the invention, the cooling device is formed from at least one baffle, the at least one baffle is hollow and the at least one baffle is formed as a through-flow of the lubricant baffle.

Advantageously, the cooling device has at least one fan for cooling the at least one component or the at least one guide plate and at least one housing component and / or at least one motor of the vacuum pump.

Frequently, the housing and / or the motor are cooled by vacuum pumps via cooling fins on the housing. For this purpose, fans are usually provided, which circulate air, so that the air flows past the cooling fins. For effective supply of air from the fan to the cooling fins baffles are often provided. According to the invention, these baffles are hollow and the lubricant is passed through the baffles. The baffles thus represent simultaneously a cooling device for the lubricant.

An embodiment of the invention provides that the at least one guide plate has a wavy surface. Advantageously, the at least one guide plate is formed from identical parts.

The pump housing is cooled by forced convection. Part of the baffles used is advantageously replaced by two flat equal parts with wavy surface and approximately constant wall thickness. The oil flow is now promoted by the volume between the two parts. The already generated airflow can be used in this way to cool both the housing exterior surface of the pump housing and the lubricant. A high conductivity material supports the effect. Parts made of aluminum can be produced by die casting or other methods. In this embodiment, a lower flow resistance occurs compared to a pipe of the same surface. In addition, additional functionality is achieved through filter elements that are easy to clean or replace in operation without stopping.

The vacuum pump is advantageously designed as a backing pump. According to a particularly preferred embodiment, the vacuum pump is designed as a Roots piston pump.

Fig. 1

einen schematischen Längsschnitt durch eine Vakuumpumpe mit einer ersten Schmiermittelkühlung;

Fig. 2

einen schematischen Längsschnitt durch eine Vakuumpumpe mit einer zweiten Schmiermittelkühlung;

Fig. 3

einen schematischen Längsschnitt durch eine Vakuumpumpe mit einer dritten Schmiermittelkühlung;

Fig. 4

eine Einzelheit der Fig. 3;

Fig. 5

eine geänderte Einzelheit der Fig. 3;

Fig. 6

einen schematischen Längsschnitt durch eine Vakuumpumpe mit einer vierten Schmiermittelkühlung.

Further features and advantages of the invention will become apparent from the accompanying drawings, in which several embodiments of a vacuum pump according to the invention are shown by way of example only. In the drawing show:

Fig. 1

a schematic longitudinal section through a vacuum pump with a first lubricant cooling;

Fig. 2

a schematic longitudinal section through a vacuum pump with a second lubricant cooling;

Fig. 3

a schematic longitudinal section through a vacuum pump with a third lubricant cooling;

Fig. 4

a detail of Fig. 3 ;

Fig. 5

an altered detail of Fig. 3 ;

Fig. 6

a schematic longitudinal section through a vacuum pump with a fourth lubricant cooling.

Fig. 1 shows a vacuum pump 1, the housing having a plurality of sections, in particular a gear compartment section 10, a pump chamber section 12 and a distribution space section 14. The housings of the individual sections 10, 12, 14 can be made separately. Alternatively, a plurality of sections can be arranged together in a housing part. A suction opening 2 provided in the pump chamber section 12 allows the vacuum pump 1 to suck fluid in its pump chamber 2. The fluid is ejected through an ejection opening 4 likewise provided in the pump chamber section 12. As mounting means, feet 6 are provided. Alternatively or additionally, the suction or discharge opening 2, 4 forming part of the housing, for example, by appropriate design of the respective flange, be designed so that hereby the assembly of the vacuum pump takes place.

Within the vacuum pump 1, a shaft 30 is arranged, which is rotatably supported by a rolling bearing 32. On the pump chamber 12 passing through the part of the shaft 30, a piston 36 is mounted or made integral with her. The piston 36 causes the pumping effect upon rotation of the shaft 30. The shaft is rotated by a drive 38, for example an asynchronous motor, which is connected to the shaft 30 via a magnetic coupling 40. Such an arrangement allows the hermetically sealed separation of the environment and pump interior, in particular the housing sections containing lubricant. At one of the drive facing away from the end of the shaft 30, a synchronizing gear 50 is provided in a space provided in the gear room section 10, which cooperates with a not visible in this illustration second synchronizing gear on a second wave also not visible such that both waves with the same frequency, but opposite direction of rotation move each other.

The synchronizing gear 50 and the rolling bearing 32 must be supplied with lubricant. For this purpose, a lubricant filling quantity 72 is provided in the space 20. A lubricant pump 60 delivers lubricant from an inlet 80 through a lubricant line 82. The lubricant line 82 has an outlet 84. The lubricant can flow out of the outlet 84 directly on the synchronizing gear 50 and lubricate this.

An additional outlet (not shown) may also be provided to lubricate the rolling bearing 32 in the same manner. For this purpose, a return 54 is provided to supply lubricant from the roller bearing 32 back to the lubricant filling amount 72. The return 54 has for this purpose an outlet 58.

Between the drive and drive-side roller bearings, a second space 22 is provided, in which a centrifugal wheel 70 dips into a drive-side lubricant filling 74. As a result, lubricant is distributed in the second space and fed to the rolling bearing 34. From this it passes through a return 64, which opens into an outlet 68, back to the lubricant filling 74.

In principle, it is possible to arrange a blast wheel in the space 20 as well. It is the same possible to provide a lubricant pump and a lubricant circuit in the drive-side space 22.

In order to avoid overheating of the lubricant 72, the lubricant circuit consisting of the lubricant pump 60 and the lubricant line 82 has a branch 86, which leads via a lubricant line 90 to a cooling device 88.

The cooling device 88 consists of a tube with several turns, whereby the cooling effective surface is increased. In addition, air 92 can be supplied for cooling the cooling device 88.

The lubricant line 90 has an outlet 94, which supplies the lubricant again the lubricant charge 72. The outlet 94 may also be arranged to supply the synchronizing gear 50 and / or the rolling bearing 32 with the cooled lubricant.

The lubricant circuits, consisting of the lubricant pump 60, the lubricant lines 82, 90, the cooling device 88 and the branch 86 are shown only schematically.

Fig. 2 shows a modified embodiment with a vacuum pump 1. The same parts are provided with the same reference numerals.

According to Fig. 2 The lubricant circuit consisting of the lubricant pump 60 and the lubricant line 82 to the outlet 84 above the synchronizing gear 50. In the lubricant line 82, a branch 86 is provided, which promotes the lubricant into a hollow body 100. The hollow body 100 is spherical. Lubricant is conveyed by the oil pump 60 into the hollow body 100. The lubricant is distributed in the hollow body 100 on an inner wall 102. An outlet 104 of the hollow body is arranged in the direction of gravity of the lubricant, so that under the action of gravity, the lubricant from the volume can get back into the space 20. The additional surface of the hollow body 100 supports the release of heat to the environment. A material of high thermal conductivity increases the effectiveness. The lubricant is injected against the inner wall 102 of the hollow body 100, cools and flows back.

The hollow body 100 is mounted at a location above an inlet 106 of the housing 10 and need not be in the immediate vicinity of the lubricant pump 60.

As in Fig. 3 is shown, a branch 86 is provided in the lubricant circuit, which leads to a hollow body 108. The hollow body 108 is cube-shaped. It is also possible to design the hollow body 108 as a double cone, as a tetrahedron or as a pyramid. The lubricant is injected into the hollow body 108 by the pressure built up by the lubricant pump 60. There it is distributed to the inner wall 110, as to Fig. 2 described.

According to Fig. 3 the lubricant cooled in the hollow body 108 is returned to the lubricant line 82 and reaches the outlet 84.

In the region of the branch 86, the lubricant mixes with the relatively warm lubricant coming from the oil pump 60, so that cooling of the total lubricant is effected.

Fig. 4 shows the hollow body 108. On the inner wall 110 of the hollow body 108, a spiral-shaped structure 112 is arranged. The structure 112 may also be groove-shaped.

The structure 112 increases the residence time of the lubricant in the hollow body 108 and can simultaneously have a filtering effect.

According to Fig. 5 a modified embodiment of the hollow body 108 is shown. The hollow body 108 again has the structure 112 on its inner wall 110. In order to achieve additional cooling, a second housing 114, which surrounds the hollow body 108, is provided. In a gap 116, a coolant (not shown) is guided to additionally cool the hollow body 108.

Fig. 6 shows the vacuum pump 1 with the lubricant pump 60 and the schematically illustrated lubricant circuit having the lubricant line 82 and the outlet 84. In the lubricant line 82, a branch 86 is arranged, which leads into an additional lubricant line 118. About the lubricant line 118, the lubricant is fed to a hollow guide plate 120 or other component with the function of a heat exchanger. A fan 122, which is also shown only schematically, is provided for cooling the housing 10. The fan simultaneously cools the guide plate 120 and thus the guided in the baffle 120 lubricant. Via a lubricant line 124, the lubricant is supplied to the lubricant line 82 where it mixes with the lubricant coming from the lubricant pump 60 and becomes the synchronizing gear via the outlet 84 50 or if necessary the rolling bearing 32 or directly supplied to the lubricant supply 72.

reference numerals

1

vacuum pump

2

suction

4

discharging port

6

feet

10

Gear compartment section

12

Pump chamber section

14

Distribution space section

20

room

22

room

30

wave

32

Rolling

34

Rolling

36

piston

38

drive

40

magnetic coupling

50

timing gear

54

returns

58

outlet

60

lubricant pump

64

returns

68

outlet

70

Impeller or slinger

72

lubricant capacity

74

lubricant capacity

80

inlet

82

lubricant line

84

Outlet of the lubricant line 82

86

junction

88

cooler

90

management

92

Fan / airflow

94

outlet

100

hollow body

102

inner wall

104

Outlet hollow body

106

inlet

108

hollow body

110

inner wall

112

structure

114

casing

116

room

118

lubricant line

120

baffle

122

Fan

124

lubricant line

Claims (15)

1. A vacuum pump with a shaft (30) with a shaft axis, a space (20) for receiving a lubricant charge (72), at least one gear wheel (50) arranged on the shaft, with at least one roller bearing (32) for the rotary support of the shaft, with
   a lubricant pump (60) for transport of the lubricant in a lubricant circuit (60, 82),
   wherein the lubricant circuit has at least one outlet (84), wherein the outlet is configured for wetting of the at least one gear wheel and/or the at least one roller bearing with the lubricant, or wherein the outlet is configured as the feed of the lubricant into the lubricant charge (72),
   characterised in that in the lubricant circuit (60, 82), consisting of the lubricant pump (60) and the lubricant conduit (82), there is provided at least one branch (86), and in that the at least one branch (86) is connected with at least one cooling device (88, 100, 108, 120) for cooling the lubricant, and in that the at least one branch (86) leads to the cooling device (88, 100, 108, 120) via a lubricant conduit (90, 118).
2. A vacuum pump according to claim 1, characterised in that the at least one branch (86) is connected with at least one existing or at least one additional cooling device (88, 100, 108, 120, 122).
3. A vacuum pump according to claim 1 or 2, characterised in that the cooling device (88) is formed of a lubricant conduit (90) with at least one direction-changing section arranged in the lubricant conduit.
4. A vacuum pump according to claim 3, characterised in that the cooling device (88) is formed of a lubricant conduit (90) with at least one winding, at least one bend and/or at least one meandering section.
5. A vacuum pump according to claim 1 or 2, characterised in that the cooling device is formed as a hollow body (100, 108).
6. A vacuum pump according to claim 5, characterised in that the hollow body (100, 108, 120) is formed of at least two identical parts.
7. A vacuum pump according to either of claims 5 or 6, characterised in that there are arranged in the hollow body (100, 108) structures (112) for retaining the lubricant.
8. A vacuum pump according to any of claims 5 to 7, characterised in that the hollow body (100, 108) has an outlet, which is arranged in the direction of gravity of the lubricant.
9. A vacuum pump according to either of claims 1 or 2, characterised in that the cooling device is formed of at least one component having a heat exchange function.
10. A vacuum pump according to claim 1 or 2, characterised in that the cooling device is formed of at least one guide sheet member (120), in that the at least one guide sheet member (120) has a hollow configuration, and in that the at least one guide sheet member (120) is formed as a guide sheet member (120) through which the lubricant flows.
11. A vacuum pump according to claim 9 or 10, characterised in that the cooling device has a fan (122) for cooling the at least one component or the at least one guide sheet member (120), and at least one housing component (10) and/or at least one motor of the vacuum pump (1).
12. A vacuum pump according to claim 10 or 11, characterised in that the at least one guide sheet member (120) has an undulating surface.
13. A vacuum pump according to any of one of claims 10 to 12, characterised in that the at least one conductive sheet (120) is formed of identical parts.
14. A vacuum pump according to any one of the preceding claims, characterised in that the vacuum pump (1) is configured as a forevacuum pump.
15. A vacuum pump according to any one of the preceding claims, characterised in that the vacuum pump (1) is configured as a Roots-type pump.

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