EP0579888B1 - Rotating scroll pump - Google Patents

Description

Field of the Invention

• wobei die spiralförmig verlaufenden Rippen mehrstufig ausgebildet sind, und wobei die mehreren Stufen unter Bildung eines Zwischenraumes räumlich voneinander getrennt sind,
• und wobei die radial äussere Stufe mindestens einen Förderraum mehr aufweist als die radial innere Stufe.

The invention relates to a rotating spiral pump, consisting essentially of a housing in which two displacement disks are rotatably arranged, the two displacement disks being provided on one side with spirally extending ribs which interlock to form delivery spaces and with their free end faces against the seal opposite displacement disc,

• wherein the spirally extending ribs are formed in several stages, and the several stages are spatially separated from one another to form an intermediate space,
• and wherein the radially outer step has at least one delivery chamber more than the radially inner step.

State of the art

A spiral pump with rotating displacement disks is known from DE-C-2603462, Fig.5. It is characterized by an almost pulsation-free conveyance of the gaseous working medium, which consists, for example, of air or an air / fuel mixture, and can therefore be used with advantage for charging purposes of internal combustion engines. During the operation of such a compressor, along the conveying space between the spiral ribs several, roughly crescent-shaped work rooms included. These move from an inlet to an outlet, their volume constantly decreasing and the pressure of the working fluid being increased accordingly. With these spiral loaders, the delivery rate for a given delivery rate and the maximum boost pressure are determined by the drive ratio, especially since the internal pressure ratio is fixed by the selected spiral geometry. In this known machine, a displacement disk is mounted on an axle stub. The second disc is non-rotatably connected to a drive shaft. On the occasion of the rotation of the first disc, the second disc is taken along in the same direction and at the same rotational speed. Both disks perform a relative movement in the form of a circular displacement.

Another such loader is known from CH-A-501 838. The variant shown in FIGS. 6 and 7 is a multi-speed, single-stage machine. One of the two rotating disks is connected to a central drive shaft. When this one disk is rotated, the second disk is taken along in the same direction of rotation by means of power transmission via the spiral ribs. The fixed axis on which the second disc is mounted is hollow in order to lead the working medium to be conveyed out of the machine. These multi-speed machines have the advantage that, on the one hand, each displacement disc is completely balanced and, on the other hand, that a more even, almost pulsation-free conveying is possible. In addition, the radial displacement of the two disks and thus the eccentricity between the two axes of rotation is smaller than in single-engined machines, which leads to lower sliding speeds between the spiral ribs. In principle, therefore, higher speeds can be driven with this type of loader.

From this same publication, a multi-stage spiral pump is also known. However, it is a catchy machine that also does not rotate, but orbits, i.e. works with spiral ribs fixed on one side. Since internal compression occurs between the work rooms connected in series in multi-stage machines, special precautions must be taken to convey non-compressible media such as liquids. When conveying compressible media, the increasing temperature in the downstream work rooms is a problem.

An orbiting machine known from DE-A-35 25 933 also has the multi-stage as its object and the feature that the outer stage has one more conveying space than the inner stage. However, this machine has no actual gaps between the two stages suitable for cooling purposes.

Presentation of the invention

The invention has for its object to provide a spiral pump of the type mentioned, with which high pressures can be achieved and in which temperature-related tolerance problems due to different thermal expansion can be controlled.

According to the invention, the object is achieved in that means for dissipating the compression heat are provided in the space between the exit of the radially outer step and the entry of the radially inner step, these means being arranged in a rotationally fixed manner on at least one of the displacement disks.

5 and 6 of GB-A-2,034,409 a machine is known which is of a multi-stage design and has coolant between the radially outer and the radially inner stage. However, this machine is a so-called orbiting machine, which is characterized by a circular movement of a displacer in a fixed delivery space. During the operation of such a machine, the inevitably occurring temperature differences between fixed and orbiting spiral parts can have a disadvantageous effect. For this reason and in order to reduce the outlet temperature from the machine in the case of heavily loaded machines, intermediate cooling between the two stages is provided in GB-A-2,034,409. The conveyed medium is led out of the machine for cooling purposes immediately after the first stage. There it is cooled in an external cooler and in turn fed to the high pressure stage in the machine. In addition, in the known machine there is only a single delivery space both in the radially outer step and in the radially inner step

With the spatial separation of the stages, you have a simple means to divide the pressure drop between the various stages depending on the application, whereby the space available on the displacement disks can be optimally used. The compression heat generated up to that point can be dissipated via the coolant in the space between the exit of the radially outer step and the entry of the radially inner step. The coolants can be ribs around which spirals extend on one of the displacement disks in the intermediate space. Or the space in the form of a flowed box can be arranged on the mutually facing end faces of the displacement disks, this box is provided on its outer walls with cooling fins.

It is expedient if the sides of the displacement disks facing away from one another are provided with ventilation blades. With this measure, the displacement disks and previously the bearing parts of the machine can be cooled.

Brief description of the drawing

Fig. 1

einen Längsschnitt durch eine erste Spiralpumpe gemäss Linie 1-1 in Fig. 4;

Fig. 2

eine Ansicht einer ersten Verdrängerscheibe;

Fig. 3

eine Ansicht einer zweiten Verdrängerscheibe;

Fig. 4

einen Querschnitt gemäss Linie 4-4 in Fig. 1;

Fig. 5

einen Querschnitt durch eine zweite Spiralpumpe;

Fig. 6 und 7

Ansichten der in Fig. 5 gezeigten Verdrängerscheiben in kleinerem Massstab.

Fig. 8

einen Längsschnitt durch eine dritte Spiralpumpe gemäss Linie 8-8 in Fig. 9;

Fig. 9

einen Querschnitt gemäss Linie 9-9 in Fig. 8;

In the drawing, three embodiments of the invention are shown schematically.
Show it:

Fig. 1

a longitudinal section through a first spiral pump according to line 1-1 in Fig. 4;

Fig. 2

a view of a first displacement disc;

Fig. 3

a view of a second displacement disc;

Fig. 4

a cross section along line 4-4 in Fig. 1;

Fig. 5

a cross section through a second spiral pump;

6 and 7

Views of the displacement discs shown in Fig. 5 on a smaller scale.

Fig. 8

a longitudinal section through a third spiral pump according to line 8-8 in Fig. 9;

Fig. 9

a cross section along line 9-9 in Fig. 8;

In the various figures, the same elements are denoted by the same reference numerals, but, depending on the exemplary embodiment, by different indices A, B and C. The direction of flow of the working fluid is indicated by arrows. In all of the examples shown, the working medium is conveyed from the radially outside to the radially inside, but this is not mandatory.

Way of carrying out the invention

In order to explain the basic functioning of the pump, which is not the subject of the invention, reference is made to the already mentioned CH-A-501 838. Only the machine structure and process flow necessary for understanding the invention are briefly described below.

The machine shown in FIGS. 1 to 4 is a two-stage pump, in which the radially outer stage is double-geared, the radially inner stage is single-geared.

In Figure 1, 1A denotes the housing composed of two halves. The two halves are connected to one another via fastening eyes, not shown, for receiving screw connections. In the right half of the housing, a stub shaft 2A is arranged in a housing hub 10A and protrudes into the interior of the housing. The left housing half is penetrated in its housing hub 11A by a drive shaft 3A. The longitudinal axes 4A, respectively. 5A of the stub shaft 2A and the drive shaft 3A are offset from one another by the eccentricity e. The fact that the eccentricity e in FIG. 1 has a small value is due to the oblique intersection in FIG. 4.

The rotatable displacement disk 6A is placed loosely on the stub axle 2A. Your hub 8A is supported by two roller bearings 13A and 14A on the stub shaft and axially secured. The left displacement disk 7A is integrally connected to the drive shaft 3A. The shaft 3A is supported in the housing hub 11A by means of two roller bearings 15A and 16A and is axially secured.

The displacement disks 6A and 7A, the end views of which can be seen in FIGS. 2 and 3, essentially consist of a flat plate 17A or 18A, which run parallel to one another in the assembled state (FIG. 1) and of ribs which are perpendicular to the respective plate are held. These ribs are spiral, i.e. they can either be classic spirals or they can be composed of several circular arcs connected to each other.

The ribs 19A and 20A on the driving displacement disk 7A and the ribs 21A and 22A on the driven displacement disk 6A are designed in two stages.

On the driving displacement disk 7A, the ribs 19A of the outer step have an arc length of 450 °, the radially inner 90 °, i.e. the last arc section has a significantly smaller radius of curvature. With this measure, an internal compression is already carried out in the first stage. The plate 18A is equipped with two such ribs 19A, the ribs being offset from one another by 180 °. This leads to the designation "two-course". In such a two-speed machine, two parallel spaces 23A are formed in the arrangement shown, through which the medium is conveyed.

The cooperating ribs 21A of the outer stage on the driven displacement disk 7A are configured accordingly, i.e. with a total arc length of 450 ° and with a last arc section which has a substantially smaller radius of curvature.

The nested spiral ribs in the assembled state can be seen in FIG. 4. On the occasion of the operation during the rotary movement, the two opposite conveying spaces 23A open against the spaces 24A at a distance of 1/2 rotation. The spirals open on the outer diameter likewise at a distance of 1/2 rotation against the inlets 25A from which they draw in fresh air. As a result of the multiple, alternating, mutual approach of the ribs, the crescent-shaped working spaces result in the conveying spaces 23A, which are displaced through the spirals from the inlets 25A in the direction of spaces 24A.

From these spaces 24A, the working medium reaches the second stage, which is of a single-thread design. On the driving displacement disk 7A, the spiral rib 20A of this inner step has an arc length of 360 °. Correspondingly, the rib 22A of the driven displacement disk 6A is formed, which also has only an effective arc length of 360 °, but which, according to FIG. 2, has a total wrap angle of two revolutions, since it must form the walls delimiting on both sides for the conveying space 26A. The transition from the rib 21A to the rib 22A is not possible without material accumulation 27. In order to balance the mass, this inevitable asymmetry can be taken into account in that the inner spiral 22A is provided with a correspondingly dimensioned, thickened spiral outlet 28 at its arch end.

The medium conveyed through the single conveying space 26A of the second stage enters the outlet 29A and is subsequently led out of the machine through the hollow stub shaft 2A.

It goes without saying that not only the radial seal between the ribs - that is to say the sealing of the delivery spaces in the circumferential direction - is important for proper functioning. The axial tightness of the delivery rooms is also important. For this purpose, the ribs must rest with their end faces on the plates 17A, 18A of the displacer disk located opposite each other. This is usually done by means not shown Sealing strips, which lie in corresponding grooves in the free end faces of the ribs.

In the spaces 24A there are coolant for the working medium heated in the first stage due to the compression, between the outlet of the radially outer ribs 19A, 21A and the inlet of the radially inner ribs 20A, 22A. These are each a number of ribs 30A with flow around them, which are arranged only on the driven displacement disk 6A and extend in a spiral in the two intermediate spaces 24A. Their axial length can correspond to the axial length of the spiral ribs. Their wall thickness, their cross-sectional shape, which can of course differ from the rectangular shape shown, and the selected material, provided the cooling fins are not made in one piece with the displacement disk, is determined depending on the heat to be dissipated. The number and the staggering of these cooling fins take into account the spatial conditions in the interspaces, as can be seen in particular in FIG. 2. The flow around the cooling fins can be seen from FIG. The medium flowing out of the upper step outlet flows through the right space, which is divided into three actual cooling channels by means of two cooling fins. At the outlet of these cooling channels, this pre-cooled medium mixes with the partial flow that flows out of the lower step outlet. The mixture then flows through the left space, which is divided into four cooling channels by means of 3 cooling fins. Their outlets are staggered in such a way that the partial flows can still unite in the gap and that there is a homogeneous flow at the inlet cross-section of the second stage.

The cooling fins 30A dissipate the heat to the displacement plate 17A. To cool them, their rear side is provided with a plurality of radially extending ventilation blades 31. For reasons of symmetry, the displacement plate 18A also has such Ventilation wing on. These vanes suck in fresh air via openings 32 in the immediate area of the housing hubs 10A, 11A, guide them past the walls of the displacement disks to be cooled and expel them again via openings 33 on the outer housing diameter. The fresh air conveyed in this way flows around the housing hubs 10A, 11A and dissipates part of the heat generated in the bearings 13A to 16A.

The machine shown in FIGS. 5 to 7 is a two-stage pump, in which the radially outer stage has four gears, the radially inner stage has two gears. For the sake of clarity, the spirals 21B and 22B arranged on the displacement disk 6B are shown in broken lines in FIGS. 5 and 7. The four outer conveying spaces 23B, which are each offset by 90 ° in the circumferential direction, open into the two intermediate spaces 24B from which the two inner conveying spaces 26B are acted upon. These two conveying spaces 26B are offset from one another in the circumferential direction by 180 ° in each case. During the rotary movement, the four successive conveying spaces 23B open at a 1/4 revolution against the spaces 24A. At their outer diameter, the spirals also open at a 1/4 turn against the inlets, not shown, from which they draw in fresh air.

It can be seen from the views in FIGS. 6 and 7 that the two displacement disks 6B and 7B are of central symmetry and therefore do not require any special balancing measures.

In the gaps 24B, which continuously narrow from the exit of the first stage to the entry of the second stage, there is a problem-free channeling and thus intermediate cooling of the partial flows emerging from the first stage can be carried out. For this purpose, three equidistant cooling fins 30B each extend over the entire length of the interstices, which are arranged on one of the two displacement disks, here, for example, the driven disk 7B, and which each form four cooling channels of the same width.

In the two examples considered so far, the spatially separated steps and the spaces together with the cooling fins are each on the same plate side of the displacement disks.

A modified flow guide is shown in FIGS. 8 and 9. The machine there is a two-stage pump, in which the radially outer stage is double-geared and the radially inner stage is single-threaded.

According to FIG. 8, 1C denotes the housing composed of two halves. Housing hubs 10C, 11C are arranged in the two halves and protrude into the interior of the housing. The two displacement plates 17C and 18C of the rotatable displacers 7C and 6C are provided with stub shafts 12 and 9 on their rear side. These stub axles are supported by bearings 15C, 16C and 13C, 14C in the housing hubs 11C, 10C. The longitudinal axes 5C, respectively. 4C of the two shaft ends are offset by the eccentricity e. The system is driven by a drive shaft 3C, which is mounted outside the displacement disks by means of ball bearings 38 in the housing 1C. On this shaft there are pulleys 39 which drive the pulleys 41 via toothed belts 40, which in turn are connected in a rotationally fixed manner to the displacement plates 17C and 18C.

The cross section in Fig. 9 shows only the nested spirals on their respective displacer discs 7C and 6C. For the sake of clarity, the spirals 19C and 20C of the displacement disc 7C are cross-hatched. In the illustrated case, the spiral ribs 19C, 20C of the outer step have an arc length of 1¼ turns, the last quarter, in turn, as in the machine according to FIG. 4, being designed with a significantly smaller radius of curvature. Each of the displacer plates 17C and 18C is equipped with two such spiral ribs 19C, 20C, the ribs of one plate being offset from one another by 180 °. In contrast to the machine according to FIG. 4 just mentioned, the spiral arrangement is the outer step. The displacer plates 17C and 18C are constructed in such a way that, in the case of nested spirals, their inlet ends no longer lie in the same plane, but are also offset by 90 ° in the circumferential direction.

In such two-speed machines, two parallel conveying spaces 23C are formed. On the occasion of operation, these working spaces open at the radially inner end at a 1/4 turn distance from the respective step outlet. On the outer diameter, the spirals open in the same rhythm against the inlets 25C, from which they draw in fresh air. At least as far as the outer stage is concerned, such a machine is characterized by the fact that, on the one hand, each displacement disc is completely balanced and, on the other hand, that more even, almost pulsation-free conveying is possible.

The second stage is catchy. On the one displacement disk 7C, the spiral rib 20C of this inner step has an arc length of one turn, ie 360 °. The rib 22C of the other displacement disk 6C is formed accordingly, which also has only an effective arc length of 360 °, but which is an entire one Has wrap angle of two turns, since it must form the walls bounding on both sides for the delivery chamber 26C.

The medium conveyed through the conveying space 26C of the second stage enters the outlet 29C and is subsequently led out of the machine housing through the hollow shaft stub 12.

The intermediate cooling of the medium leaving the first stage takes place in annular co-rotating boxes 34, the inner spaces of which form the intermediate spaces 24C. One box each is arranged on the back of the displacement plates 17C and 18C, which is not provided with spiral ribs. In order to introduce the medium to be cooled into the box, the plates are provided with openings 35 at the respective spiral end. The medium is deflected in the box and flows back through a further opening 36 to the inlet-side end of the second stage. To dissipate the heat, the boxes are provided with cooling fins 30C on their outer wall. To separate the two stages from one another, an annular wall 37 is attached to one of the displacement plates 17C and seals against the cooperating displacement plate 18C. This can be done in the manner of the spiral ribs with sealing strips inserted in the grooves. The ring wall is located in a radial plane between the kidney-shaped openings 35 and 36.

Reference list

1

casing

2nd

Stub axle

3rd

drive shaft

4, 5

Longitudinal axis

6, 7

Displacement disk

8th

Hub of 6

9

Wave stub (Fig. 8)

10.11

Housing hub

12th

Wave stub (Fig. 8)

13, 14

Rolling bearings for 8

15, 16

Rolling bearings for 3

17, 18

Displacement plate

19, 20

Ribs of the driving displacement disk 7

21, 22

Ribs of the driven displacement disk 6

23

Promotional areas

24th

Gaps

25th

Inlets

26

Funding area

27

Material accumulation

28

thickened spiral outlet

29

Outlet

30th

Cooling fin in the space

31

Ventilation wing

32

Opening in 1st

33

Opening in 1st

34

box

35

breakthrough

36

breakthrough

37

Ring wall

38

ball-bearing

39

Pulley

40

Timing belt

41

Pulley

e

eccentricity

A

Indices for 1st embodiment (Fig. 1 to 4)

B

Indices for 2nd embodiment (Fig. 5 to 7)

C.

Indices for 3rd embodiment (Fig. 8 and 9)

Claims (4)

1. Rotating spiral pump, essentially consisting of a casing (1) in which two displacement discs (6, 7) are arranged rotatably, the two displacement discs each being provided on one side with spirally extending ribs (19, 20, 21, 22) which engage in one another for the purpose of forming conveying spaces (23, 26) and which seal off relative to the opposite displacement disc by means of their free end faces,

   - the spirally extending ribs being of multi-stage design, and the plurality of stages being separated spatially from one another to form an interspace (24),

   - and the radially outer stage having at least one conveying space more than the radially inner stage (23 or 26),

   characterized
   in that means (30) for dissipating the heat of compression are provided in the interspace (24) between the exit of the radially outer stage and the entrance of the radially inner stage, these means being arranged fixedly in terms of rotation on at least one of the displacement discs (6, 7).
2. Spiral pump according to Claim 1, characterized in that the cooling means are ribs (30A, 30B) round which the flow circulates and which extend spirally on one displacement disc (7A, 7B) in the interspace (24A, 24B) from the exit of the radially outer stage to the entrance of the radially inner stage.
3. Spiral pump according to Claim 1, characterized in that the interspace (24C) is arranged in the form of a box (34), through which the flow passes, on those end faces of the displacement discs facing away from one another, and in that the cooling means are ribs (30C) with which the outside of the box (34) is equipped.
4. Spiral pump according to Claim 2, characterized in that at least the displacement disc (6A) which carries the cooling ribs (30A) is provided with ventilation vanes (31) on the rear side.

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