DE20307911U1 - scroll pump - Google Patents

Description

Rev: May 19, 2003 .· ; ;.; ; "VdJv^c iGmÖH 03 0190 002

Scrol!pump

The present innovation concerns a scroll pump - also called a spiral pump - for conveying gases or gas-condensate mixtures. This pump has an inlet, an outlet, a fixed stator disk and a rotating rotor disk that is attached to a drive shaft. The stator disk and the rotor disk are essentially parallel to each other and each have spiral-shaped flanks that engage with each other to form variable conveying chambers.

The operating principle of spiral pumps has been known for a long time. For example, DE 28 26 071 C2 describes a spiral pump, which shows in particular different designs of the spiral elements in order to avoid delivery pressure pulsations. In general, in the spiral or scroll pump, two spiral-shaped flanks or ribs engage with each other, whereby the delivery chamber formed between these flanks is continuously displaced from the outside to the inside by the rotation of at least one of these disks. The medium enclosed in the delivery chamber is continuously transported along the flanks and is usually discharged from the pump after reaching the center of the spirals.

EP 0 579 888 A1 discloses a rotating spiral pump in which the spiral-shaped ribs are divided into several segments in order to achieve high pressures and avoid temperature-related tolerance problems.

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Previously known scroll pumps have the problem that condensate can collect between the spiral-shaped flanks, which is difficult to transport away through the spiral-shaped pumping chamber and thus severely impairs the pump's pumping performance. If, for example, condensate forms due to the pressure that builds up against a normally present outlet valve and the pump is taken out of operation, a residual amount of condensate remains in certain sections of the pumping chamber, which leads to increased wear on the pump, particularly when pumping aggressive media.

Known scroll pumps have a horizontal drive shaft so that the disks with the spiral flanks are vertical. This arrangement means that the condensate that has accumulated in the pumping chamber cannot be removed even after the pump has been switched off.

The purpose of this innovation is therefore to provide an improved scroll pump in which the accumulation of condensate in the pumping chamber is reduced. To this end, the condensate that occurs in the pumping chamber should be easily drained to the outside and should not remain in the pumping chamber even when the pump is not running. Another sub-purpose of this innovation is to reduce the tendency for condensate to form within the pumping chamber. Finally, the aim of the innovation is to make the scroll pump insensitive to aggressive media and to reduce the size of the pump unit coupled to a drive motor.

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The above-mentioned task is solved by the scroll pump according to the innovation in that the drive shaft is arranged essentially vertically in the operating state, so that the discs are essentially horizontal. In addition, the outlet starts from the center of the disc located below and is directed outwards in such a way that any condensate that may be present can flow away due to gravity.

This design prevents the accumulation of condensate in the lower areas of the pumping chamber, as the condensate flows automatically to the outlet due to gravity and can be discharged from there. The scroll pump therefore does not have to actively pump any condensate that may occur, so the pumping capacity is not affected.

According to a preferred embodiment, no outlet valve is connected to the outlet of the scroll pump. This allows the pumped gases or vapors to pass through the outlet unhindered without having to overcome the opening pressure of an outlet valve. These changed pressure conditions reduce the tendency of vapors to condense, so that less condensate is formed in the pumping chamber from the outset. By consistently using the operating principle of the scroll pump, a working valve can also be dispensed with on the inlet side. This makes it possible to build the pump according to the innovation completely without valves, which can increase the long-term functional reliability compared to pumps with working valves.

In a particularly useful embodiment of the innovation, a seal is attached to the free end of the spiral-shaped flanks, which rests against the opposite disc to seal the conveying chamber. This

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The seal separates the adjacent pumping chambers between the individual turns of the spiral. This seal also seals the pumping chambers from the bearings and other housing parts, so that aggressive media only occur within the pumping chamber, which can be made of a resistant material. In this way, a gas-tight pump chamber can be created in which no bearings need to be integrated, so that, for example, error-prone and complicated shaft seals or gas-tight ball bearings can be dispensed with.

It is particularly useful if the seal mentioned is inserted in a front groove in the flanks and projects slightly beyond the flanks in the axial direction. In this way, a small channel is created at the transition between the seal and the flank, which allows any condensate present to drain away in each section of the spiral flanks, even if the conveyor disk of the scroll pump is not moving. Condensate can therefore flow outwards by gravity alone, even after the pump has been shut down.

In a preferred embodiment, the drive shaft to which the conveyor disk is attached directly merges into the output shaft of an electric motor or is formed in one piece with it. The drive motor can thus be positioned in the immediate vicinity of the scroll pump, so that the size of the entire unit is minimized. In addition, coupling elements between the shafts can be dispensed with, which reduces the assembly effort and component costs. In modified embodiments, however, a different connection can also be used.

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connection between scroll pump and drive motor. For example, standard flange motors can be coupled to the pump.

Further advantages and details of the present innovation emerge from the following description of a preferred embodiment, with reference to the drawing. They show:
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Fig. 1 is a simplified side sectional view of a scroll pump with an electric motor;

Fig. 2 is a simplified view of the scroll pump from below;
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Fig. 3 a sectional detailed view of a stator disk and a rotor disk with respective flanks.

In Fig. 1, a scroll pump according to the invention is shown in a side sectional view. The scroll pump has a housing 1 in which a fixed stator disk 2 and a rotatable rotor disk 3 are arranged. The fixed stator disk can also be part of the housing 1. In the embodiment shown, the stator disk 2 is located below the rotor disk 3. In modified embodiments, however, a reversed arrangement could also be selected.

The rotor disk 3 is mounted on a drive shaft 4, through which rotation can be caused. In the preferred embodiment shown here, the drive shaft 4 is simultaneously part of an electrical

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Motor 5 so that it functions as its output shaft. The drive force provided by the motor is therefore transmitted to the rotor disk 3 without gear and coupling elements. This simplifies the construction of the complete unit and reduces the required size. However, modified embodiments can also use independent motors.

The two disks 2, 3 each have flanks 6 that extend from the respective disk in the direction of the opposite disk. Since the basic functioning of a spiral or scroll pump is known to the expert, the usual structure of the disks and the flanks does not need to be described in detail here. In principle, the flanks 6 are arranged in a spiral shape on the respective disk and engage with one another in such a way that a variable conveying chamber 7 is provided between them.

The decisive factor for the improved functionality of the scroll pump is the fact that it is operated with a vertical drive shaft 4. As a result, the stator disk 2 and the rotor disk 3 are essentially horizontal. If condensate occurs in the conveying chamber 7 formed between the flanks during operation of the scroll pump, it collects on the lower disk due to gravity, i.e. on the bottom surface of the stator disk 2 in the embodiment shown. While the medium to be pumped is introduced into the scroll pump via an inlet 8 at a relatively random location, an outlet 9 is located at the lowest point of the conveying chamber, approximately in the center of the lower disk. The condensate collects at this point without affecting the conveying capacity.

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pump would be required, solely due to the effect of gravity. Of course, the pumping pump also supports the discharge of the condensate. The outlet 9 is preferably led out without an intermediate outlet valve, so that the condensate (and the pumped gas) can flow out of the scroll pump without pressure, both during operation and at rest. By omitting an outlet valve, the pumped gas does not have to be subjected to an increase in pressure at the pump outlet, so that condensation hardly occurs. It should be noted that no inlet valve needs to be switched on in the inlet either. The scroll pump can therefore be constructed completely without working valves.

Fig. 2 shows the scroll pump in a view from below. The inlet 8 and the outlet 9 are directed to the side. However, it is crucial for the functioning that the outlet 9 begins in the plane of the lower boundary of the pumping chamber. Fig. 2 also shows that a fan wheel 10 is arranged below the disks 2, 3, which serves to supply cooling air to the entire unit. The fan wheel is also attached to the drive shaft 4.

Fig. 3 shows a detailed view of the stator disk 2 and the rotor disk 3. It can be seen that the respective flanks 6 originate from one disk and run adjacent to each other in the direction of the opposite disk. To seal the individual conveying chambers 7, a seal 11 is arranged on the front side of each flank 6, whereby only a single seal is shown in Fig. 3 for the sake of simplicity. The seal 11 can be formed by a sealing strip which is adapted to the media to be conveyed and

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should also have a low coefficient of friction so as not to unnecessarily hinder the rotation of the rotor disk 3. The seal 11 rests on the bottom surface of the opposite disk on its side facing away from the flank 6. The seal 11 also seals the pump chamber from the bearings. No shaft seals or other gas-tight connections to ball bearings are therefore required, resulting in an inexpensive and functionally reliable design.

Preferably, the seal 11 is placed in a groove 12 which runs in the front side of the flank 6. Because the seal 11 protrudes slightly beyond the flank β, the front side of the flank 6 does not rub on the bottom side of the opposite disk during operation of the pump. In addition, a small channel 13 remains between the seal 11 of the adjacent flank 6 and the opposite disk, which allows condensate to flow away even when the scroll pump is at a standstill. This channel can be kept so small that the pump's delivery capacity is hardly affected. In this context, it should be remembered that the scroll pump can be operated at around 1,500 revolutions per minute, for example, to deliver gases. At the resulting flow speeds, air gaps or channels that are kept small enough do not have a negative effect on the delivery capacity. It is therefore also not necessary for the flanks 6 to lie against one another during rotation of the rotor disk 3. Rather, a minimal air gap is left to keep pump wear to a minimum.

Modifications to the embodiment described here are possible without any problems. However, it is important to ensure that the vertical position of the drive shaft and thus the horizontal

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The position of the stator disk and the rotor disk must be maintained to ensure condensate drainage. The outlet must always be located at the lowest point of the pumping chamber so that the condensate collecting there can be drained out of the pump by gravity.

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List of reference symbols

1 Housing 2 Stator disc 3 Rotor disc 4 drive shaft 5 engine CTi flanks 7 Conveying room 8th inlet 9 Outlet 10 Fan wheel 11 poetry 12 Groove 13 channel

Claims (12)

1. Scroll pump for conveying gases or gas-condensate mixtures with an inlet ( 8 ), an outlet ( 9 ), a fixed stator disk ( 2 ) and a rotatable rotor disk ( 3 ) which is fastened to a drive shaft ( 4 ), these disks ( 2 , 3 ) lying essentially parallel to one another and each having spiral-shaped flanks ( 6 ) which engage with one another to form variable conveying chambers ( 7 ), characterized in that the drive shaft ( 4 ) is arranged essentially vertically in the operating state, so that the disks ( 2 , 3 ) lie essentially horizontally, that the outlet ( 9 ) starts from the center of the disk located below and is guided outwards in such a way that any condensate that may be present flows away due to gravity. 2. Scroll pump according to claim 1, characterized in that no outlet valve is inserted into the outlet ( 9 ) to hinder the pressure-free discharge of the gas or condensate. 3. Scroll pump according to claim 1 or 2, characterized in that a seal ( 11 ) is attached to the free end of the spiral-shaped flanks ( 6 ), which seal rests against the opposite disc for sealing the delivery chambers ( 7 ). 4. Scroll pump according to claim 3, characterized in that the seal ( 11 ) is inserted into a front-side groove ( 12 ) in the flanks ( 6 ) and projects slightly beyond the flanks ( 6 ) in the axial direction, so that a minimal channel ( 13 ) remains between the seal ( 11 ) and the foot of the adjacent flank section under all operating conditions, which allows the drainage of condensate to the outlet ( 9 ). 5. Scroll pump according to claim 4, characterized in that the seal ( 11 ) also seals the delivery chambers ( 7 ) with respect to the bearings and housing parts ( 1 ). 6. Scroll pump according to claim 5, characterized in that the seal ( 11 ) is arranged so that additional seals on moving components for sealing the delivery chamber ( 7 ) are not required. 7. Scroll pump according to one of claims 3 to 6, characterized in that the seal ( 11 ) is a sealing strip made of Teflon, graphite and rubber. 8. Scroll pump according to one of claims 1 to 7, characterized in that the rotor disk ( 3 ) is arranged above the stator disk ( 2 ). 9. Scroll pump according to one of claims 1 to 8, characterized in that the drive shaft ( 4 ) is formed integrally with the output shaft of an electric motor ( 5 ). 10. Scroll pump according to one of claims 1 to 9, characterized in that the drive shaft ( 4 ) further carries a fan wheel ( 10 ) which transports cooling air to the disks ( 2 , 3 ) and optionally to the motor ( 5 ). 11. Scroll pump according to claim 10, which refers back to claim 9, characterized in that the motor ( 5 ) is positioned above the rotor disk ( 3 ), the stator disk ( 2 ) is part of the housing ( 1 ) of the scroll pump and the fan wheel ( 10 ) is attached to the drive shaft ( 4 ) below the stator disk ( 2 ). 12. Scroll pump according to one of claims 1 to 11, characterized in that no inlet valve is connected to the inlet ( 8 ).