EP2195511B1 - Spiral-type positive-displacement machine - Google Patents

Abstract

In a positive displacement machine for compressible media, having a spiral-shaped feed chamber (11) arranged in a housing (7b) between cylinder walls (14, 15), a spiral-shaped displacement body is composed of a disc (2) with spiral-shaped strips (3). The strips (3) are held eccentrically with respect to the housing, in such a way that, during operation, each point of the strip performs a movement which is limited by the peripheral walls of the feed chamber. The contour (20) of the disc is formed, in the overlapped region of the spiral at the point provided for the mutual sealing of the traversed chambers (11, 16), in the shape of the movement path. The housing edge (19) is formed, as a transition between the raised first part (17) and lowered second part (18) of the outer cylinder wall (14) of the housing, as a bulbous thickened portion. The radial extent "D" of the thickened portion is at least as great as the degree of eccentricity ("e"). In periods of machine operation, in which a higher pressure prevails in the outer, sickle-shaped working space (11) than in the suction chamber (16), the circular-arc-shaped projection (19) together with the contour of the disc forms a sealing line (21) which extends over the height of the projection.

Description

Field of the invention

The invention relates to a spiral compressor with double spiral for compressible media according to the introductory part of patent claim 1.

State of the art

Spiral compressors with double spiral, for example, by the DE 2603462 A1 known. A built-up according to this principle compressor is characterized by virtually pulsation-free promotion of existing example of air or an air-fuel mixture gaseous working fluid and therefore could be used inter alia for charging purposes of internal combustion engines with advantage. During operation of such a compressor, a plurality of approximately crescent-shaped working spaces are trapped along the displacer chamber between the spirally-shaped runner and the two peripheral walls, moving from the inlet through the displacer chamber to the outlet, with their volume constantly reduced and the pressure of the working fluid is increased accordingly.

A machine of the type mentioned, in which the spirals spanning a total wrap angle of about 360 °, is known from the DE 3407939 C1 , In such a machine, the rotor, there called rotary piston, held to its leadership relative to the housing at its inlet end by a rocker whose length is greater than the length of the drive crank. The disc carrying the spiral strips terminates with the outer contour of the non-overlapped strips and the contour of the disc in the overlapped area is formed in the shape of the movement path which defines a housing edge, which by the necessary lowering of the outer cylinder wall of the delivery chamber on a housing half to record the disc has arisen when swinging the rotor in this area. Between the housing edge and the disc remains depending on the position of the rotary piston varying residual gap, which shorts the delivery chambers at the inlet and at the exit of the spiral. When conveying the compressible medium from the outside to the inside, this means that a backflow takes place through this residual gap. This residual gap should remain the same for half a crank, which is why the contour of the disc has an approximate S-shape. With this rotary piston machine, the number and the length of the pressure loss causing gap between the respective pressure and suction chamber should be avoided, resulting in a reduction of the power loss result. Due to the fact that the disk carrying the spiral-shaped strips terminates with the outer contour of the non-overlapped strips, the machine is characterized by its low construction volume and low weight.

Such, more than 20 years old machine, which in principle has a proper seal, the current requirements no longer meet, because on the one hand a residual gap with permanent connection between the pressure and suction chamber is basically no longer permissible and the other a residual gap As small as it may be, which stays the same for only half a crank, it is not enough to ensure the required tightness.

The same considerations apply to the sealing arrangements of spiral veins, as they are known from the EP-A-0 284 774 (to be regarded as the nearest Tecknik stand and EP-A-0 560 009 are known. The inventions based there is based on the idea that, on the occasion of the circular movement, only such delivery rooms communicate in which the same pressure prevails. At different pressures in the adjacent rooms each seal is effective. However, this principle is only possible with nested arrangement of at least two spirals, ie when at least two, in this case offset by 180 ° to each other, spirally extending displacement body are arranged on one side of the disc. Applying the principle to discs that have only one spiral per side, so there are exactly the same problem as in the above-mentioned DE 3407939 C1 , Namely, it remains between the housing edge and the disc depending on the position of the disc depending varying residual gap, which shorts the delivery chambers at the inlet and at the outlet of the spiral during a large part of the crankcase, whereby an impermissible reflux occurs.

Presentation of the invention

The invention is therefore an object of the invention to provide a machine of the type mentioned in which in particular in the low speed range adjacent conveyor spaces in which different pressures prevail, are completely sealed from each other.

This object is achieved with the characterizing features of claim 1.

The advantages of the invention are to be seen in the fact that they both in a scroll compressor with double spiral with rocker as a guide element for the displacer and with guide shaft for guiding the displacer, as for example from the DE 3107231 A1 is known, can be used. Furthermore, the invention allows a - viewed in the radial direction - outwardly free arrangement of the rocker, if such as a guide element is assumed. The invention is particularly effective when used in machines with internal compression, as in the above-mentioned DE 2603462 A1 are described and in the above-mentioned DE 3107231 A1 are shown graphically.

Short description of the drawing

Fig. 1

einen Läufer,

Fig. 2

eine Ansicht eines Gehäuseteils mit erfindungsgemässer Gestaltung der Gehäusekante,

Fig. 3

einen Längsschnitt durch die Maschine,

Fig. 4

eine Draufsicht auf das Gehäuseteil nach Fig. 2 mit eingelegtem Läufer nach Fig. 1,

Fig. 5-6

Draufsichten wie in Fig. 4, jedoch mit unterschiedlichen Winkelstellungen des Exzentertriebes.

In the drawing, an embodiment of the invention is shown schematically.
It shows:

Fig. 1

a runner,

Fig. 2

a view of a housing part with inventive design of the housing edge,

Fig. 3

a longitudinal section through the machine,

Fig. 4

a plan view of the housing part after Fig. 2 with inlaid runner behind Fig. 1 .

Fig. 5-6

Top views as in Fig. 4 , but with different angular positions of the eccentric drive.

Way to carry out the invention

For the purpose of explaining the operation of the compressor, which is not the subject of the invention, reference is made to the already mentioned DE 2603462 A1 directed. In the following, only the machine construction and process sequence necessary for the understanding will be briefly described:

1 in the drawing denotes the rotor of the machine as a whole. It consists of a disk 2 and from both sides axially of the disk 2 vertically projecting spiral strips 3. According to Fig. 1 is the spiral, ie, the bar 3 is formed of a plurality of adjoining circular arcs and has a wrap angle of about 360 °. In this case, the outlet-side end of the spiral is equipped with a slight so-called internal compression, as they are known from the above DE 2603462 A1 is known. This is worth mentioning in that the higher pressure in the working space caused by the internal compression has a perfect seal as a condition. At the spiral outlet a plurality of apertures 6 are provided in the disk 2, so that the medium can pass from one side of the disk to the other, for example, in a central outlet 13 (FIG. Fig. 2 ) to be deducted. 4 with the hub is designated, with which the disc 2 is mounted on a roller bearing 22 on an eccentric disc 23. This is in turn part of a drive shaft 24. "e" means the eccentricity between the axis 9 of the drive shaft 24 and the axis 10 of the eccentric disc 23rd

It can be seen from the illustration that the disk 2 carrying the spiral-shaped strips 3 terminates on the predominant part of its circumference with the outer contour of the strips 3. This area is considered to be the non-overlapped spiral area and is decisive for the keeping of the outside diameter of the machine. The angle dimension "OV" indicates the overlapped area of the spiral. In that area, the disc 2 projects radially beyond the strips 3. With 5 in this area "OV" is a radially outside of the strips 3 arranged eye designated for receiving a guide bearing, not shown, which is mounted on a guide pin 30. The contour of the disc 2 is formed at the location provided for the mutual sealing of the (to be explained later) delivery chambers 11 in the form of the path of movement of the disc. In the example, it is a recess 20 which is elliptical.

In Fig. 2 the housing half 7b of the assembled from two halves, via fastening eyes 8 for receiving screw connections connected machine housing is shown. 11 denotes the delivery chamber, which incorporated in the manner of a spiral slot in both housing halves is. It runs parallel from an outer circumference of the spiral disposed in the housing inlet 12 to an interior provided for the outlet 13. The delivery chamber 11 has substantially approximately parallel, approximately equally spaced cylinder walls 14, 15, which like the strips 3 a spiral include. In an intake chamber 16, which connects the inlet 12 with the delivery chamber 11, an axis 28 is provided for the rotatable mounting of the guide device.

Since in the area "OV" the disc 2 protrudes beyond the strips 3, it must penetrate at least one half of the housing. This happens in the present case on the illustrated housing half 7b. For this purpose, the inner web 18 of the housing half 7b relative to the outer web 17 is lowered at an appropriate point of the housing - at one edge of the overlapped region "OV" of the spiral - by the amount of the disc thickness. This measure has, inter alia, the advantage that in the lower half of the housing 7b, a sealing strip (not shown) is to be arranged only at the inner web, which seals the delivery space 11 against the suction space 16 up to the outlet 13. Due to this necessary lowering of the outer cylinder wall on at least one half of the housing, here 7b, for receiving the disc 2 when swinging the rotor in this area creates a housing edge 19th

From the longitudinal section according to Fig. 3 , Which represents the assembled machine, it can be seen that the drive shaft 24 is mounted in the two housing halves 7a and 7b by means of unspecified rolling bearings. It is rotated by a pulley 26 in rotation. The drive of the rotor 1, the drive shaft 24 worried about the eccentric disc 23. On this disc 23 sits the bearing 22, shown here as a rolling bearing, which is sealed on both sides via shaft seals 25 against the housing interior. Also on both sides of the eccentric 23 sitting counterweights 27 on the drive shaft 24th

The leadership of the rotor 1 is concerned by the guide means 29. Depending on whether the guide means 29 from a rocker or from a with the drive shaft synchronously running guide shaft (not shown), perform all points on the strips 3 an elliptical or a circular displacement movement. In the example, the guide means 29 consists of a rocker 31, one end of which is rotatably mounted about the axis 28 in the housing ( Fig. 2 ), while the other end engages over the guide pin 30 in the eye 5 of the rotor.

Out Fig. 4 It can be seen that when the runner 1 is engaged, the strips 3 between the cylinder walls 14 and 15 of the housing 7 engage. Their curvature is dimensioned so that the strips almost touch the inner 15 and the outer 14 cylinder wall, for example, at one point in each case. During operation, the strips 3 slide with linear contact points to the cylinder walls 14 and 15. As a result of the multiple alternating approach of the strips 3 to the inner 15 resp. Outer cylinder wall 14 of the delivery chamber 11 arise on both sides of the strips 3 sickle-shaped, the working medium enclosing working spaces, which are displaced during the drive of the rotor 2 through the delivery chamber 11 in the direction of the central outlet 13. This reduces the volumes of these working spaces and the pressure of the working fluid is increased accordingly.

As far as spiral compressors are known with double spirals or derive from professional interpretation at least from the above-mentioned prior art, however, with the disadvantages mentioned above. So that during operation certainly adjacent flowed through spaces in which different pressures prevail, are completely sealed from each other, now according to the invention, the operatively connected elements 19 and 20 are coordinated. Here, the term "kreisbogenähntich" is used in the following, since it is the heel in the disc, ie at their authoritative contour, only to their location at the periphery of the disc and not to the exact description of their geometric shape. The latter is determined by the type of guide used. Thus, in the double-shaft eccentric drive, all points of the rotor describe a circle in which the rocker is described as a guiding element only the center of the hub of the runner a circle, the remaining points describe an ellipse-like curve. As in Fig. 4 Shown below, a guide means 29 with rocker 31 is used. In this solution, it is possible to arrange the operatively connected elements 19 and 20 geometrically between the two bearing points of the guide device 29. This has an advantageous effect insofar as the overlapped area "OV" and thus the weight of the runner can thereby be kept as small as possible. In addition, the flow path between inlet 12 and suction chamber 16 is shortened.

The tuning of the essential elements for the correct functioning is now as follows: The housing edge 19, which forms the transition between raised first part 17 and lowered second part 18 of the outer cylinder wall 14 is formed as a bulbous thickening. Their extension "D" in the radial direction should be at the widest point of the thickening at least half as large as the measure of the eccentricity "e". The thickening is formed as a substantially circular paragraph, wherein extension "D" in this case represents the diameter of the paragraph. The recess 20 of the disc is then formed in the shape of its trajectory, depending on the geometry of the thickening arc similar, here elliptical. Based on all operating conditions in which in the outer crescent-shaped working space, which is formed by the strips 3 and the outer cylinder wall 14, a higher pressure prevails than in the suction chamber 16 outside the second part 18 of the outer cylinder wall 14. In these periods should no backflow be possible from the crescent-shaped working space. For this purpose, the size of this recess 20 is adjusted so that its contour cooperates during these periods with the circular shoulder of the housing edge 19. A cooperation for the purpose of forming an actual sealing line 21 extending over the heel.

As the housing edge 19 on the occasion of the machine operation for the purpose of forming a sealing line 21 with the recess 20 of the disc cooperates show the 4 to 6 , The respective angular position of the runner is most easily recognized by the position of the counterweights 27.

In Fig. 4 the position of the rotor 1 is registered, in which the crescent-shaped outer working space formed by the strips 3 and the outer cylinder wall 14 is completely enclosed. It can be seen that the sealing line 21 is engaged. From this representation it is also apparent that the diameter "D" of the edge 19, if it is circular, must have a certain minimum size in order for the operative connection to function. The mere rounding off of the housing wall to break off, as they are known from the DE 3407939 C1 is known, does not lead to success.

Upon displacement of the rotor 1 in the conveying direction, which in Fig. 4 is indicated within the counterweight 27 by an arrow, this outer crescent-shaped working space is reduced in volume and connected to the central outlet 13. The pressure in the work area increases; the seal against the suction chamber 16 is given by the rolling of the circular arc-shaped / similar recess 20 on the edge 19 with constant formation of a sealing line 21st

Fig. 5 shows the outermost angular position at which a seal still takes place. The ejection of the working fluid from the outer working space is almost completed. Work equipment is already expelled from the inner workspace. This outermost sealing line is extremely important in order to avoid that compressed working fluid from the spiral end flows back into the suction chamber.

After all, it can be seen that with the present invention, a type of seal has been created which operates over an angular range of about 250 °.

Fig. 6 shows the area where a seal is unnecessary, even unwanted. The recess 20 has now lifted off the edge 19; it takes place in this Area no seal instead. At this time, working fluid is conveyed out at the end of the spiral from the inner working space towards the outlet 13, and already sucked back into the inner working space from the inlet 12 at the beginning of the spiral. The outer working space is open at the end of the coil against the suction chamber 16 and at the beginning of the spiral against the inlet 12, which facilitates its filling. A backflow of compressed working fluid from the inner working space around the spiral end into the suction chamber 16 is not possible, since at this time in the exit-side region of the spiral, the strip 3 seals against the outer cylinder wall 14.

Claims (2)

1. Spiral compressor with a double spiral for compressible media, with a spiral-shaped feed chamber (11) arranged in a fixed housing (7a, 7b) between cylinder walls (14, 15) for arrangement of a rotor (1-4), comprising essentially a disc (2), and spiral-shaped strips (3) mounted on at least one side of the disc and held eccentrically in relation to the housing in such a way that each point of the strips executes during operation a movement which is limited by the peripheral walls of the feed chamber, with the disc which supports the spiral-shaped strips terminating with the outer contour of the strips in a so-called non-overlapped region, and with the contour of the disc in a so-called overlapped region ("OV") is projecting radial over the strips (3) at the location provided for the mutual sealing of traversed chambers (11, 16) in the form of a movement path which defines a housing edge (19), which housing edge (19) is established by the required lowering of the outer cylinder wall (14) of the feed chamber (11) on at least one of the housing halves (7b) for receiving the disc during inward swinging of the rotor in this region as transition between raised outer web (17) and lowered inner web (18) of the outer cylinder wall (14), characterized in that the housing edge (19) is also established at the location provided for the mutual sealing of traversed chambers (11, 16) as essentially circular bulbous thickened portion wherein in radial direction the extent "D" of the thickened portion which is sized at the widest location is at least half as great as the degree of the eccentricity "e" of an axis (9) of a driving axle (24) and an axis (10) of an eccentric disc (23) on which the disc (2) is brought up and that in the periods during operation of the machine in which a higher pressure prevails in the outer sickle-shaped work space, defined by the strips (3) and the outer cylinder wall (4), than in the suction chamber (16) arranged radially outside the outer cylinder wall (14), this essentially circular bulbous thickened portion (19) cooperates with an essentially circular or elliptical recess (20) of the disc (2), which encompasses the disc in form of a movement path, in order to form a sealing line (21) which extends over the height of the transition.
2. Spiral compressor with a double spiral according to claim 1, characterized in that the cooperating bulbous thickened portion (19) and disc contour (20) are arranged towards the outlet-side end of the spiral.

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