CN108223371A - Spiral shell formula compressor - Google Patents

Abstract

The invention relates to a screw compressor with a stator screw, a rotor screw capable of being driven along a track and a base respectively assigned to the stator screw and the rotor screw, said base being located relative to the axis of the track of the rotor screw axially delimits a pressure chamber delimited by a stator helix and a rotor helix in a radial direction with respect to the orbital axis of the rotor helix, characterized in that the rotor helix is relative to the associated The bottom of the can be arranged relative to the movement. Therefore, the base assigned to the rotor screw should not follow the movement of the rotor screw along the track, which makes the base statically integrated in the screw compressor and in particular the housing of the screw compressor, thereby supporting the pressure due to pressure. Axially directed force generated by pneumatic overpressure in the cavity. As a result, complex measures for compensating the pressure acting axially on the carrier bottom of the rotor screw, for example by integrating so-called intermediate pressure chambers, can be avoided.

Description

screw compressor

technical field

The invention relates to a screw compressor or a scroll compressor which can be provided in particular as a coolant compressor for an air conditioner of a motor vehicle.

Background technique

In principle, screw compressors have a number of advantages over other types of compressors, such as piston compressors, which make screw compressors predestined for use as coolant compressors for air conditioners in motor vehicles. As a result, screw compressors are, for example, more robust, more efficient and can also be produced inexpensively. Furthermore, the screw compressor is designed to have relatively small dimensions due to its radial direction of action when compressing the gas provided for this purpose, in particular along the axis of rotation of the drive shaft of the screw compressor.

Screw compressors (see for example US 2013/0115123 A1) essentially comprise one or more screw pairs which engage one another nestedly in an eccentric arrangement and thereby define a plurality of mutually independent, screw-shaped or Sickle-shaped pressure chamber. During the relative orbital movement of the spirals (of each spiral pair), the pressure chamber first opens at its radially outer end to the low-pressure section of the screw compressor, so that the gas to be compressed can flow into the pressure chamber . During a further relative movement of the spirals, the respective subsequently closed pressure chambers move on a helical path towards the central region, wherein the size of the pressure chambers decreases continuously. This results in compression of the gas enclosed in the pressure chamber according to the principle of extrusion. The central area of the screw is usually connected with the high-pressure section of the screw compressor with an autonomous valve in the middle, and the compressed gas is injected into the high-pressure section when it reaches the maximum compression pressure due to the reduction in the size of the pressure chamber. The relative movement of the two helixes (of each helix pair) is usually achieved by an orbital drive of the (rotor) helix, while the other (stator) helix is designed to be stationary.

In order to achieve the highest possible efficiency of the screw compressor, it is expedient for the rotor screw and the stator screw to seal against each other as well as possible at the contact points. The sealing of the gap formed between the end edge of the spiral wall of the spiral and the base of the associated counter-spiral is often problematic, since the compression of the gas in the compression space is thus relatively high. A pressure of 100 will develop which pushes the spirals away from each other along the track axis or longitudinal axis. Of course, the higher the compression ratio achieved with the help of a screw compressor, the more serious the problems that arise. Problems therefore arise especially in these screw compressors, which are designed for the use of coolants such as carbon dioxide (R744) and The conventional synthetic coolants (eg R134a, R1234yfF, R12) previously used require significantly higher system pressures. Furthermore, carbon dioxide as a coolant has a relatively small molecular size, so that significant leaks would already be possible in relatively small gaps.

It is known here to provide so-called intermediate pressure chambers, which are provided with the aid of one or A plurality of intermediate pressure channels are fluidically connected to one or more pressure chambers. In this case, the one or more intermediate pressure channels have a relatively small opening cross section, so that they act as a throttle for the gas flowing between the pressure chamber and the intermediate pressure chamber. As a result, an intermediate pressure is established in the intermediate pressure chamber due to the flow-conducting connection to one or more pressure chambers, the intermediate pressure being between the suction pressure and the end-of-compression pressure, and the intermediate pressure due to the intermediate pressure channel The throttling effect results in significantly less fluctuations than the pressure of the gas or gaseous coolant in the pressure chamber. The intermediate pressure in the intermediate pressure chamber acts on the base of the screw of the screw pair and thus presses the base axially against the associated counter screw.

DE 10 2013 200 807 A1 discloses a screw compressor in which the rotor screw is connected to an inner ring of a pivot slide mechanism, wherein the inner ring is also mounted rotatably on the eccentric end of the drive shaft. The inner ring is also connected to the fixed outer ring by a plurality of oscillating members. The swivel slide mechanism ensures that the rotary drive via the drive shaft only causes a movement of the rotor helix along the path, and does not also cause it to twist relative to the stator helix.

Contents of the invention

The problem underlying the invention is to provide a screw compressor which, despite its simple and thus inexpensive design, ensures good sealing of the pressure chamber delimited by the screw and the associated base.

The technical problem is solved according to the invention by a screw compressor with a stator screw, a rotor screw that can be driven along a track, and a base assigned to the stator screw and the rotor screw, respectively, wherein said bottom delimits a pressure chamber axially relative to the orbital axis of the rotor helix, said pressure chamber being bounded radially relative to the orbital axis of the rotor helix by the stator helix and the rotor helix According to the invention, the rotor screw is arranged so that it can move relative to the associated base. An advantageous embodiment of the screw compressor according to the invention results from the following description of the invention.

According to the invention, the screw compressor has a stator screw, a rotor screw that can be driven along an orbit, and a base that is assigned to the stator screw and the rotor screw respectively, wherein the base is aligned with respect to the orbital axis of the rotor screw The axial direction of the orbital axis around which the rotor helix is movable at least partially, preferably completely, delimits a pressure chamber bounded by the helix in a radial direction with respect to the orbital axis of the rotor helix . It is provided here that the rotor screw is arranged so that it can move relative to the base associated therewith. Therefore, the base should not follow the orbital movement of the rotor screw, which results in a static integration of the base in the screw compressor and in particular in the housing of the screw compressor, thereby enabling alignment of the shaft in an advantageous manner. Support for the force that is generated as a result of the pneumatic overpressure in the pressure chamber. In particular it can therefore be provided that as far as possible only the rotor screw is able to move along the track, while the stator screw and the two bases associated with the screw are integrated stationary in the screw compressor. In this way, the overpressure in the pressure chamber of the screw compressor essentially does not lead to axial forces acting on the rotor screw, so that the sealing of the screw can be achieved in a simple manner. Sealing is required in the inventive screw compressor for both screws even with respect to both bottoms. Therefore, in the screw compressor according to the invention, it is possible to dispense with expensive structural measures for compensating the pressure acting on the bottom of the orbital movement of the rotor screw, which without such measures would lead to Screw compressors lack tightness, and in particular the integration of so-called intermediate pressure chambers can be dispensed with, whereby the structural design for the screw compressor according to the invention can be complicated and thus also the production costs can be kept relatively low. Furthermore, the screw compressor according to the invention is also characterized by relatively small orbiting masses, which can advantageously influence the efficiency and/or the acoustic performance of the screw compressor. The embodiment of the screw compressor according to the invention also has the advantage of relatively low friction losses and, in particular, a relatively high efficiency.

In a preferred embodiment of the screw compressor according to the invention it can be provided that the base of the rotor screw is at least axially relative to the track axis to the stator screw and/or to the stator screw The bottoms of are connected immovably (spacing or preferably directly). In this way, a particularly favorable support of the pressure in the axial direction relative to the track axis due to the pneumatic overpressure in the pressure chamber can be achieved. A particularly advantageous support can be achieved if the two bases and thus the parts which are pressed directly in the axial direction relative to the track axis are directly connected to one another, for example by means of screws.

In addition, it can preferably be provided that the base assigned to the stator screw and/or the base assigned to the rotor screw forms a section of the housing of the screw compressor. In particular, it can also be provided here that the sides of the bases which are remote from the associated screw part are the outer sides of the housing or of the screw compressor. Such a screw compressor according to the invention can be characterized by a particularly compact design and thus takes up relatively little installation space.

In order to achieve the best possible sealing of the screw with respect to the bottom and thus also of the screw compressor according to the invention as a whole, it can preferably be provided that the rotor screw and the stator screw It is arranged axially between the bases with as little play as possible. Due to the static integration of the two bottoms in the screw compressor achieved according to the invention, it is possible to adjust in a structurally relatively simple manner by adapting the parts connecting the bottoms to each other to form the smallest possible gaps that can be obtained in a very small area. largely independent of the pressure relationship in the pressure chamber. Due to manufacturing tolerances, however, it is generally not possible to achieve maximum play-freeness here. In addition, the thermally related differential expansion of the components of the screw compressor during operation, by which the distances of the bases to one another and the distances of the bases to the screw, may be changed, must be taken into account. Therefore, in order to ensure the best possible sealing of the screw part relative to the base at any time during the operation of the screw compressor according to the invention, additional measures should preferably be taken, which, for example, also ensure that the screw is always sealed during thermally related expansions. The arrangement of the elements between the bases with as little play as possible, while at the same time keeping the frictional losses as a result of the relative movement of the base relative to the screw as small as possible. For this purpose it can preferably be provided that the rotor screw and/or the stator screw are designed to be flexible and in particular elastic at least in the axial direction relative to the track axis. For this purpose, it can be provided that the spiral wall of the rotor spiral and/or the spiral wall of the stator spiral itself is at least partially formed from a flexible or preferably elastic material, for example an elastomer or a thermoplastic. Alternatively or additionally, it is also possible to integrate one or more separate seals which are arranged movable at least in the axial direction on the base body forming the spiral wall of the respective spiral and are for example prestressed by means of one or more The spring element is supported on the base body and is thereby loaded onto the adjoining base.

In a further preferred embodiment of the screw compressor according to the invention it can be provided that the axis of rotation of the drive for the rotor screw is arranged radially offset relative to the track axis. In this way, it is advantageously possible to implement a design for the bottom associated with the rotor screw, which is as free as possible of through-holes and can in particular also be designed in one piece, which has a bearing on the pressure chamber seal and/or the shaft It is beneficial in terms of support to pressure.

It can also preferably be provided that the rotor screw is connected to a guide which surrounds the rotor screw at least partially on the outer circumference and which guide forms a rotation lock for the rotor screw. The torsion lock here ensures that the process of generating the orbital movement of the rotor screw by means of the drive is independent of the relative rotation of the rotor screw relative to the stator screw. The extension of the guide on the outer peripheral side of the rotor helix only in a relatively small section (for example in a section rotated by a maximum of 180°, a maximum of 120° or a maximum of 90° relative to the orbital axis of the rotor helix) is essential for achieving the guide. The function of the primer is sufficient. A relatively small guide element can also have an advantageous effect with regard to the magnitude of the orbiting mass and with regard to friction losses and thus the efficiency and acoustic behavior of the screw compressor according to the invention. It can also advantageously be provided here that the guides are arranged only on the outer peripheral side of the rotor helix, so that the entire inner region of the rotor helix, in which the rotor helix is connected to the stator helix, can be covered axially by the associated base. The components cooperate to delimit the pressure chamber, which in turn can be advantageous with regard to the sealing of the pressure chamber and/or the support of the axial pressure.

The preferably provided guides of the screw compressor according to the invention can also preferably be used to transmit the drive movement along the track to the rotor screw, said drive movement being passed through the central drive (that is to say the axis of rotation of the drive relative to the track axis) or preferably a non-central drive (that is to say the axis of rotation of the drive is arranged radially offset relative to the axis of the track), so that additional transmission elements can be dispensed with, which in turn achieves as small a movement along the track as possible It is advantageous in terms of quality and in terms of frictional losses as small as possible.

For the screw compressor according to the invention, a drive with an electric drive motor can advantageously be provided, since this drive also enables a required power regulation of the screw compressor in a particularly simple manner. In contrast to a mechanically driven screw compressor according to the invention, for example, the integration of a clutch for power regulation can be dispensed with. Such a power regulation may be necessary or at least desirable, for example, when preferably using a screw compressor according to the invention as a coolant compressor for a motor vehicle air conditioner, so that the energy consumption for the screw compressor and the resulting This also keeps the fuel consumption of the internal combustion engine of the motor vehicle for directly or indirectly providing the energy to operate the screw compressor as low as possible. Furthermore, such an electric motor-driven screw compressor can also be used in motor vehicles with a partially or fully electrified drive train (independent of the operation of a possibly present internal combustion engine).

Due to the advantageous support of the axial pressure achieved by the design of the screw compressor according to the invention, and thus due to the good sealability of the pressure chamber, the screw compressor according to the invention is also advantageously suitable for producing Relatively high pressure ratios, eg at least 15, preferably at least 25. As a result, such screw compressors are also particularly suitable as coolant compressors for air conditioners in motor vehicles, in which coolants are used which require correspondingly high system pressures, such as carbon dioxide (R744), for which To ensure the functionality of the air conditioner. A corresponding configuration can be provided for the screw compressor according to the invention, by means of which correspondingly higher system pressures can be achieved.

It can also be provided here that the screw compressor according to the invention is designed in one stage and thus has only one screw pair consisting of a stator screw and a rotor screw. As a result, although the entire compression ratio has to be achieved with the aid of the sealing stage, which places correspondingly high demands on the sealing stage, especially with regard to the thermal loading of this sealing stage and with regard to the tightness between the stator screw and the rotor screw, at the same time it is possible The structural complexity and the installation space of the screw compressor are kept low, so that the screw compressor can be produced relatively cheaply and used advantageously. A multi-stage compressor according to the invention is also possible.

The indefinite article ("a"), especially in the claims and generally in the description enunciating the claims, should not be read as a numeral. Accordingly, a component thus embodied accordingly should be understood to exist at least once and may exist multiple times.

Description of drawings

The invention is explained in greater detail below with reference to the exemplary embodiments shown in the drawings. Simplified respectively in the accompanying drawings:

Figure 1 shows an exploded perspective view of a screw compressor according to the present invention; and

FIG. 2 shows a perspective, partly transparent view of a screw compressor.

Detailed ways

The screw compressor shown in FIG. 1 comprises a multi-part housing in which a double-walled stator screw 10 is immovably integrated. The stator screw 10 is here in one piece and is thus connected completely seamlessly to the flat, substantially circular housing section 14 of the first housing part 12 , wherein the housing section 14 forms a fitting. Belonging to the bottom 14 of the stator helix 10, the pressure chamber is arranged between the stator helix 10 and the rotor helix 18 embedded in the stator helix 10 eccentrically with respect to the track axis 16, and the pressure chamber is composed of the stator helix 10 and the rotor helix The part 18 delimits in a radial direction with respect to the track axis 16 , and the pressure chamber is delimited by said bottom in one of the axial directions with respect to the track axis 16 . The stator helix 10 is also surrounded by a circular circumferential delimiting wall 42 which is likewise integral and is thus connected seamlessly to the planar housing section 14 of the first housing part 12 . The first housing part 14 also includes a jacket-shaped housing section 20 which (completely) surrounds the stator helix 10 and the delimiting wall 42 on the circumferential side. Integrated in the housing section 20 are ports 24 for (in the exemplary embodiment shown, for example two) feed channels 22 into the limiting wall 42 , via which the gas to be compressed can be introduced into the pressure chamber. .

The housing also includes a second housing part 26 which likewise has a flat housing section 28 which is designed approximately in the shape of a circular segment. The housing section 28 is provided with a base 28 assigned to the rotor screw 18 , by means of which base 28 delimits a pressure chamber in the other axial direction with respect to the track axis 16 . Furthermore, the second housing part 26 is likewise provided with a housing-shaped housing section 30 . In the installed state of the screw compressor (see FIG. 2 ), the two housing parts 12, 26 are directly connected to each other by means of unshown connecting parts, such as bolts, wherein the housing shapes of the two housing parts 12, 26 The housing segments 20, 30 are supported relative to each other.

Due to the only partially circular design of the planar housing section 28 , the second housing part 26 forms a cutout 32 which has the shape of a circular arc extending about 120° around the track axis 16 . Arranged in this section 32 is a guide 34 which likewise has the shape of a circular arc extending around the track axis 16 by approximately 120° and which is fixed and in particular integrally connected to the adjoining section of the rotor screw 18 connected, in particular to the section at the radially outer end of the rotor screw 18 . In this case, the guide 34 is situated axially next to the rotor screw (with reference to the track axis 16 ) and radially (with reference to the track axis 16 ) on the outside of the rotor screw 18 , so that the entire rotor screw The delimited, spiral-shaped inner volume of the part 18 is covered only (on the respective side) by the base 28 assigned to the rotor screw part 18 and not also by the guide part 34 .

The function of the guide 34 is to guide the orbital movement of the rotor screw 18 by means of a drive (not shown) and thereby (to a large extent) prevent the rotor screw 18 from rotating relative to the stator screw 10 , An anti-twist effect is thereby achieved. Provision is made for this that the guide part 34 is designed with a plurality of cylindrical guide grooves 36 into which cylindrical guide pins 38 of the first housing part 12 engage. The guide pin 38 extends from a further housing section 40 which is arranged in a section of the first housing part 12 which is arranged one above the section 32 of the second housing part 26 , and The further housing section 40 connects the edge section of the jacket-shaped housing section 20 with the delimiting wall 42 of the first housing part 12 in an essentially parallel orientation with respect to the planar housing section 14 . The segments are connected and thus form a support and guide surface for the guide 34 . The diameter of the guide groove 36 (dimensioned identically for all guide grooves 36 ) is significantly greater than the diameter (dimensioned identically for all guide pins 38 ) of the guide pin 38 . The orbital movement of the guide 34 and thus the rotor screw 18 can be guided by the sliding of the guide pin 38 on the circumferential surface of the guide groove 36 .

A further function of the guide element 34 is to act as an orbital motion transmission element which transmits an orbital movement imposed on it by means of a drive (not shown) to the rotor screw 18 .

The orbital movement of the rotor helical part 18 relative to the stator helical part 10 has the known result that the pressure chambers each move on a helical track in the direction of the central section of the stator helical part 10 and thereby become ever smaller. , whereby the partial volume of gas or partial volume of gas-oil mixture contained in the pressure chamber is continuously compressed. When the oil-air mixture is compressed in this way, oil is mixed into the gas before or during the start of the compression in order to lubricate the contact surfaces formed in particular between the stator screw 10 and the rotor screw 18 by means of the oil, whereby Relatively small frictional losses can be achieved. If the individual pressure chambers reach the central section of the stator helix 10 , the compressed part-volume gas or part-quantity oil-gas mixture passes through the three integrated in the bottom 14 assigned to the stator helix 10 in the present embodiment. The discharge port sprays out. In this case, the compressed gas or the gas-oil mixture flows out of the pressure chamber as ideally as possible pressure-dependently by means of an independently pressure-controlled valve 44 (non-return valve) assigned to the discharge opening.

The ejection of the compressed gas or the gas-oil mixture through the outlet opening can also take place in a high-pressure chamber (not shown), which is formed, for example, by the housing, from which the compressed gas is discharged centrally. If the oil-air mixture is already compressed or compressed in the pressure chamber, an oil separator (not shown), for example designed as a centrifugal separator, can also be integrated in the high-pressure chamber, by means of which the oil is separated from the gas as completely as possible And realize reuse (that is, add oil back into the gas that still needs to be compressed).

As shown, the valve 44 can be designed as a finger valve or as a flap valve, for which purpose the valve each includes a spring strip or lug 46 , which is passed through one end, for example Fastened by means of screws (not shown) to the outer side of the base 14 assigned to the stator screw 10 or to the outer side of the housing section 14 of the first housing part 12 forming the base 14 , while the spring suspension The free ends of the lugs 46 are each arranged one above the associated outlet opening and close the outlet opening in the unloaded state of the spring lug 46 . When an overpressure occurs inside the pressure chamber fluidly connected to the outlet opening compared to the pressure outside the valve 44 , the valve 44 opens, wherein the free end of the spring lug 46 is elastically deflected. The overpressure on the outside leads conversely to the fact that the free end of the spring lug 46 presses more strongly against the section of the base 14 surrounding the outlet opening, so that the valve 44 securely closes the outlet opening.

According to the design of the screw compressor of the present invention, the static integration of the bottom 28 in the screw compressor can be realized due to the relative movable arrangement of the bottom 28 assigned to the rotor screw 18 relative to the rotor screw 18, through which According to the described configuration, the pressure caused by the overpressure in the pressure chamber, which is directed in the axial direction relative to the track axis 16, can be supported in an advantageous manner by the bottom 14, 28 designed as a housing section, while the rotor No axially directed pressure acts on the screw 18 or on the unit formed by the rotor screw 18 and the guide 34 (at the relevant height). A good sealing of the gap formed between the screw part 10 , 18 and the base 14 , 28 can thus be achieved in a structurally relatively simple manner, since the pressure-dependent width of the gap can be easily and reliably passed through the connecting housing part 12 . , 26 and thus the appropriate dimensioning of the connecting piece connecting the bottom 14, 28 is avoided, as in the screw compressors of the type described according to the prior art without costly compensating measures (such as integrating so-called intermediate pressure chambers) The gap occurs in the case of .

List of reference signs

10 Stator screw

12 first housing part

14 Flat housing section of the first housing part/bottom of the stator helix

16 track axis

18 Rotor screw

20 Shell-shaped housing segment of the first housing part

22 input channels

Connectors for 24 input channels

26 Second housing piece

28 Flat housing section of the second housing part/bottom of the rotor screw

30 Shell-shaped housing section of second housing part

32 Cutout of second housing part

34 guide

36 Guide groove for guide

38 guide pin

40 Additional housing segments of the first housing part

42 boundary wall

44 valves

46 Spring lugs for valves

Claims (8)

1. A screw compressor having a stator screw (10), a rotor screw (18) that can be driven along a track and a bottom (14) respectively assigned to the stator screw (10) and the rotor screw (18) , 28), wherein the bottom (14, 28) defines a pressure chamber in the axial direction relative to the orbital axis (16) of the rotor screw (18), the pressure chamber is relative to the rotor screw (18) The radial direction of the track axis (16) is defined by the stator screw (10) and the rotor screw (18), characterized in that the rotor screw (18) can move relative to the associated bottom (28) layout. 2. The screw compressor according to claim 1, characterized in that the rotor screw (18) and the stator screw (10) are as free as possible in the axial direction relative to the track axis (16). It is arranged with a gap between the bases (14, 28). 3. The screw compressor according to claim 1 or 2, characterized in that said rotor screw (18) and/or stator screw (10) are at least axially relative to said track axis (16) The upward direction is designed to be flexible and especially elastic. 4. Screw compressor according to one of the preceding claims, characterized in that the bottom (28) of the rotor screw (18) is at least axially relative to the orbital axis (16) The stator screw (10) and/or is non-movably connected to the base (14) associated with the stator screw (10). 5. Screw compressor according to one of the preceding claims, characterized in that the base (14) associated with the stator screw (10) and/or the base (28) associated with the rotor screw (18) form a A section of the casing of a screw compressor. 6. Screw compressor according to one of the preceding claims, characterized in that the axis of rotation of the drive for the rotor screw (18) is arranged radially offset relative to the track axis (16). 7. Screw compressor according to one of the preceding claims, characterized in that the rotor screw (18) is connected to a guide (34) which surrounds the rotor screw at least partially on the outer circumference, the guide The guide (34) forms a rotation stop for the rotor screw (18). 8. Screw compressor according to claim 7, characterized in that the drive for the rotor screw (18) acts on the guide (34).