EP2806165B1 - Scroll compressor and CO2 vehicle air conditioner with a scroll compressor - Google Patents

Description

The invention relates to a scroll compressor for a CO ₂ vehicle air conditioning system, and a CO ₂ vehicle air conditioning system with such a scroll compressor.

Non-combustible refrigerants are used for the air conditioning of motor vehicles in order to avoid the risk of explosion inside the vehicle in the event of an accident. However, the refrigerants used so far are either already banned or at least classified as problematic because of their high global warming potential. As an environmentally friendly, non-combustible refrigerant CO ₂ (R744) comes into question, which already partially replaces the existing refrigerant. However, CO ₂ air conditioners operate with high operating pressures, which make special demands on the strength and tightness of the system components. The advantage associated with the high operating pressure is that the higher density of CO ₂ requires a smaller volume flow to provide a relatively high refrigeration capacity.

A scroll compressor for a CO ₂ vehicle air conditioner with the features of the preamble of claim 1 is made JP 2006/144635 A known. From the EP 1 087 142 A2 is a scroll compressor for refrigerant is known, which has an axially movable coil for power control.

Generally, such scroll compressors have variable speed electric drives to control the cooling capacity of the compressor. In the context of vehicle air conditioners that work with conventional low-pressure refrigerant, also simple design scroll compressors are known in which a power control is done by switching off or on the compressor.

So revealed US 6,273,692 B1 a scroll compressor with a mechanical drive, which is connectable by an electromagnetic clutch with the compressor unit. Such couplings usually have a heavy steel disc. The moment of inertia is therefore high, which has a negative effect on consumption. In addition, the coupling is a costly component. US 2002/0081224 A1 discloses a variable low-pressure scroll compressor which can be switched on and off by a radial movement of one of the two scroll spirals. In this case, the eccentricity between the two scroll spirals is released, which thus get out of engagement in the radial direction.

The invention has for its object to provide a scroll compressor for a CO ₂ vehicle air conditioning, which is simple in construction and allows power control. The invention is also based on the object of specifying a CO ₂ vehicle air conditioning system with such a scroll compressor.

According to the invention the object is achieved by a scroll compressor for a CO ₂ vehicle air conditioner with the features of claim 1. With regard to the CO ₂ vehicle air conditioning system, the object is achieved by the subject matter of claim 15.

The invention has several advantages.

The use of a fixed drive, i.e., fixed, electric drive. constant speed allows cost-effective design compared to variable speed compressors. The power control is effected by the alternating movement of the counter-spiral relative to the displacement spiral in the axial direction. As a result, a pressure compensation gap is temporarily formed between the counter-spiral and the displacement spiral, so that compressed gas can flow radially outward from the chambers of the compressor which are located radially further inside. This reduces the pressure in the scroll compressor. The positive displacement spiral continues to run, so that a clutch for separating the power flow between the drive and the displacement spiral is not required. The scroll compressor according to the invention can therefore be designed clutchless.

The design of the scroll compressor as a clutchless compressor leads to a significant reduction in the mass moment of inertia. Because the displacement spiral runs in the no-load condition, eliminates the starting torque in the scroll compressor according to the invention. In addition, the load on the rotating components is greatly reduced and the consumption is reduced. The scroll compressor according to the invention is very quiet and quiet.

The alternating movement of the counter-spiral is effected by an axial release force and an opposite closing force. According to the invention, the axial release force is applied by a spring which is arranged between the displacement spiral and the counter-spiral. The release force lifts the counter-spiral from the positive displacement spiral so that the pressure equalization gap is created in between and the scroll compressor is switched off (open position). For the axial closing force, a piston is provided which engages next to the pressure chamber on the counter-spiral. The closing force brings the counter-spiral into contact with the displacement spiral. The pressure equalizing gap is closed and the scroll compressor is switched on (closed position).

The inventive arrangement of the spring and the piston leads to a compact and robust construction of the scroll compressor, which is power controlled by the alternating movement of the counter-spiral. The arrangement of the piston adjacent to the pressure chamber results in the pressure chamber being able to be connected directly to the outlet for the compressed gas formed in the counter-spiral. The pressure chamber can therefore be designed without installation, whereby problems with the tightness in the pressure chamber can be avoided.

Compared to the prior art, the invention enables the construction of scroll compressors for CO ₂ vehicle air conditioners whose mass moment of inertia is a total of a factor of 3 lower than in known scroll compressors. In absolute terms, the invention enables the construction of scroll compressors with a maximum mass moment of inertia of 500 kgmm ² .

Preferred embodiments are specified in the subclaims.

Due to the preferred arrangement of the spring relative to the pressure chamber, a particularly space-saving design can be realized. If, in addition, the piston comprises an annular piston which is arranged so as to be displaceable coaxially with the counter-spiral, the overall result is a robust construction for the initiation of the release and closing force in the counter-spiral. The annular piston also has the advantage that the closing force is introduced over a relatively large area, whereby the pressure required for the closing force of the piston is evenly distributed.

The already existing pressure differences between the high pressure and the suction side of the scroll compressor are used to actuate the piston when the piston is mounted in a piston guide which is alternately connectable to the high pressure and the suction side of the scroll compressor. In order to prevent compressed gas flowing from the high-pressure side to the suction side when the counter-spiral is lifted from the positive-displacement spiral, and the positive-displacement spiral to rotate in the reverse direction, the pressure chamber is followed by a check valve in the direction of flow. In a further preferred embodiment, the pressure chamber has a dual function and serves on the one hand for damping gas pulsations and on the other hand as a guide for the counter-spiral. For this purpose, a arranged on the high pressure side rear wall of the counter-spiral forms the bottom of the pressure chamber, wherein the counter-spiral has a flange which bears axially movably on an inner wall of the pressure chamber. This dual function contributes to the compact design of the scroll compressor.

The tightness can be improved if a closed to the suction side receiving space for the eccentric bearing fluidly connected to the pressure chamber and a rear wall of the positive displacement spiral can be acted upon by a contact pressure.

It has been found that a relatively low eccentricity is sufficient for a sufficient compression of the refrigerant. For this purpose, the distance between the center of the counter-spiral and the center of the displacement spiral maximally 1.5 mm, in particular at most 1.2 mm, in particular at most 1.0 mm, in particular maximally 0.8 mm, in particular maximally 0.6 mm, in particular maximally 0.4 mm, in particular not more than 0.2 mm. The lower limit may be 0.1 mm. Preferably, the counter-spiral has a winding angle of 660 ° to 720 °, in particular from 680 ° to 700 °, whereby a sufficient compression of the refrigerant is achieved.

In a further preferred embodiment, it is provided that the eccentric bearing is arranged in the displacement space between the displacement spiral and the counter-spiral is and has a bearing bush, which is integrally formed with the positive displacement spiral and the bottom of which is aligned with the end face of the turns of the positive displacement spiral. Thus, the bearing bush of the eccentric bearing is recessed in the direction of the high pressure side, wherein the eccentric bearing is at least partially equal to the turns of the counter-spiral. The eccentric bearing thus plunges into the counter-spiral. The used in the known low-pressure scroll compressors for final compression innermost volume between the displacement spiral and the counter-spiral is used in this embodiment, at least partially for the formation of the bearing bush and thus for receiving the eccentric bearing. This reduces any overturning moments and improves smoothness. In addition, this embodiment has the further advantage that the recessed bearing bush forms a support surface for the spring between the displacement spiral and the counter-spiral. This embodiment is therefore particularly advantageous in connection with the arrangement of the spring relative to the pressure chamber.

Any tilting moments are further reduced if the displacement spiral has a central recess in which at least partially a counterweight is accommodated, which is connected to the eccentric bearing. Preferably, the volume of the pressure chamber by a factor of 5-7, in particular by a factor of 6, greater than the suction volume per revolution of the displacement spiral, whereby gas pulsations are effectively reduced.

The invention will be explained in more detail with reference to the accompanying schematic drawings with reference to embodiments.

Figur 1

einen Längsschnitt eines Scrollkompressors nach einem erfindungsgemäßen Ausführungsbeispiel in der Offenstellung;

Figur 2

einen weiteren Längsschnitt durch den Scrollkompressor gemäß Figur 1, der den Aufbau des Exzenterlagers verdeutlicht;

Figur 3

eine Detailansicht des Scrollkompressors gemäß Figur 1 im Bereich des Gehäusedeckels;

Figur 4

eine Detailansicht wie in Figur 3, wobei sich der Kompressor in der Schließstellung befindet;

Figur 5

einen Längsschnitt durch einen Kompressor nach einem weiteren erfindungsgemäßen Ausführungsbeispiel mit einem elektrischen Antrieb mit konstanter bzw. fester Drehzahl;

Figur 6

einen Vergleich der Massenträgheit des gesamten Kompressors in kgmm² mit dem Stand der Technik;

Figur 7

einen Vergleich der wirksamen Massenträgheit beim Zuschalten des Kompressors in kgmm² mit dem Stand der Technik und

Figur 8

ein Vergleichsdiagramm für das Einschaltmoment in Nm.

In this show

FIG. 1

a longitudinal section of a scroll compressor according to an embodiment of the invention in the open position;

FIG. 2

a further longitudinal section through the scroll compressor according to FIG. 1 , which illustrates the structure of the eccentric camp;

FIG. 3

a detailed view of the scroll compressor according to FIG. 1 in the area of the housing cover;

FIG. 4

a detail view like in FIG. 3 with the compressor in the closed position;

FIG. 5

a longitudinal section through a compressor according to another embodiment of the invention with an electric drive with a constant or fixed speed;

FIG. 6

a comparison of the inertia of the entire compressor in kgmm ² with the prior art;

FIG. 7

a comparison of the effective inertia when switching on the compressor in kgmm ² with the prior art and

FIG. 8

a comparison diagram for the switch-on torque in Nm.

The scroll compressor described in detail below is designed for use in a CO ₂ vehicle air conditioning system which typically includes a gas cooler, an internal heat exchanger, a throttle, an evaporator, and a compressor. Such systems are designed for maximum pressures over 100 bar. The compressor is a scroll compressor, also referred to as a scroll compressor. As in the FIGS. 1 and 2 As shown, the scroll compressor has a mechanical drive 10 in the form of a pulley. The pulley is connected in use to an electric motor or an internal combustion engine.

The scroll compressor further includes a housing 30 having a housing cover 31 which closes the high pressure side of the compressor and is bolted to the housing 30. In the housing 30, a housing intermediate wall 32 is arranged, which limits a suction chamber 33. In the housing bottom 34, a passage opening is formed, through which a drive shaft 11 extends. The arranged outside of the housing 30 shaft end is rotatably connected to a driver 35 which engages in the rotatably mounted on the housing 30 pulley, so that a torque can be transmitted to the drive shaft 11 of the pulley. The drive shaft 11 is rotatably mounted on the one hand in the housing bottom 34 and on the other hand in the housing intermediate wall 32. The sealing of the drive shaft 11 against the housing bottom 34 is effected by a first shaft seal 36 and against the housing intermediate wall 32 by a second shaft seal 37.

The drive shaft 11 transmits the torque to a compressor unit, which is constructed as follows.

The compressor unit comprises a movable displacement spiral 13 and a counter-spiral 14. The displacement spiral 13 and the counter-spiral 14 engage each other. The counter-spiral 14 is fixed in the circumferential direction and in the radial direction. The coupled with the drive shaft 11 movable displacement spiral 13 describes a circular path, so that in a conventional manner by this movement several gas pockets or gas chambers are generated, which migrate radially between the displacement spiral 13 and the counter-spiral 14. By this orbiting movement refrigerant vapor is sucked into the open outer gas chamber and compressed with the further spiral movement and the concomitant reduction of the gas chamber. The refrigerant vapor is increasingly compressed linearly from radially outward to radially inward direction and expelled in the center of the counter-spiral 14 into a pressure chamber 15.
For the orbiting movement of the displacement spiral 13 an eccentric bearing 12 is provided, which is connected to the drive shaft by an eccentric pin 38 (s. FIG. 2 ). The eccentric bearing 12 and the displacement spiral 13 are arranged eccentrically with respect to the counter-spiral 14. The gas chambers are separated from each other pressure-tight by conditioning the Verdrängerspirale 13 on the counter-spiral 14. The radial contact pressure between the displacement spiral 13 and the counter-spiral 14 is adjusted by the eccentricity.

A rotational movement of the displacement spiral is avoided by a plurality of guide pins 39, which, as in FIG. 2 shown, are mounted in the intermediate wall 32. The guide pins 39 engage in corresponding guide bores 40 which are formed in the displacement spiral 13. A counterweight 28 is connected, preferably in one piece, to the eccentric bearing 12 to compensate for the imbalance caused by the orbital motion of the displacer coil 13.

The in FIGS. 1 . 2 shown scroll compressor is clutchless. In order to still be able to change the performance of the compressor, the scroll compressor is switched on and off (digital circuit). For this purpose, it is provided that the counter-spiral 14 in the axial direction, ie in a direction parallel to the drive shaft 11 is alternately movable. The displacement spiral 13 is fixed in the axial direction.

Thus, the counter-spiral 14 can be lifted from the displacement spiral 13 in the axial direction, as in the FIGS. 1 to 3 shown. In this open position, a pressure equalizing gap 41 is created between the displacement spiral 13 and the counter-spiral 14, which connects the gas chambers, which are separated from each other in the radial direction, between the displacement spiral 13 and the counter-spiral 14. This is good in FIG. 3 to see. Due to this pressure equalizing gap 41, compressed gas flows radially outward from the chambers arranged further inwards, whereby pressure equalization takes place. The performance of the scroll compressor is thereby lowered to 0, or at least close to zero.

• Sie ist der Gegenspirale in Strömungsrichtung nachgeordnet und steht mit dieser in Fluidverbindung durch den nicht dargestellten Auslass der Gegenspirale 14. Der Auslass ist nicht exakt im Mittelpunkt der Gegenspirale 14 angeordnet, sondern befindet sich außermittig im Bereich der innersten Kammer zwischen der Verdrängerspirale 13 und der Gegenspirale 14. Dadurch wird erreicht, dass der Auslass von der Lagerbuchse 26 des Exzenterlagers 12 nicht abgedeckt wird und der endverdichtete Dampf in die Druckkammer 15 ausgestoßen werden kann.

The axial guidance required for the axial mobility of the counter-spiral 14 is fulfilled by the pressure chamber 15, which also dampens gas pulsations. The pressure chamber 15 therefore has a double function:

• It is arranged downstream of the counter-spiral in the flow direction and is in fluid communication with the outlet of the counter-spiral 14 (not shown). The outlet is not arranged exactly in the center of the counter-spiral 14, but is located off-center in the region of the innermost chamber between the displacement spiral 13 and the counter-spiral 14. This ensures that the outlet is not covered by the bearing bush 26 of the eccentric bearing 12 and the final compressed steam can be ejected into the pressure chamber 15.

For the axial guidance of the counter-spiral 14, the pressure chamber 15 at the axial end, which faces the counter-spiral 14, forms an inner sliding surface 42. The sliding surface 42 is machined and seals against the counter-spiral 14. The rear wall 21 of the counter-spiral 14 forms the bottom of the pressure chamber 15. The counter-spiral 14 therefore closes directly with the pressure chamber 15. The rear wall 21 also has a flange 22, in particular an annular flange 22, which rests against the sliding surface 42 of the pressure chamber 15. The flange 22 serves as an axial guide of the counter-spiral 14 in the pressure chamber 15. On the outer circumference of the flange 22, a groove with a sealing means, for example a sealing ring 43 is formed. The pressure chamber 15 is bounded by a peripheral wall 44 which forms a stop 45 and limits the axial movement of the counter-spiral 14.

The pressure chamber 15 is provided in the housing cover 31. As a result, the assembly of the axially movable counter-spiral 14 is simplified. In addition, it has a rotationally symmetrical cross section.

For the alternating movement of the counter-spiral 14 between the open position ( FIG. 3 ) and the closed position ( FIG. 4 ) opposite axial forces are required. The axial force, the counter-spiral 14 in the open position ( FIG. 3 ) and thus disengages the counter-spiral 14 from the displacement spiral 13 (axial release force) is generated by a spring 16 which is arranged between the displacement spiral 13 and the counter-spiral 14. The spring 16 may be formed, for example, as a plate spring. The spring 16 is in the closed position according to FIG. 4 biased and urges the counter-spiral 14 and the displacement spiral 13 apart.

As in FIGS. 3, 4 good to see, the spring 16 is disposed opposite to the pressure chamber 15. For this purpose, a central recess 46 is provided in the counter-spiral 14, in which the spring 16 is arranged. The spring 16 is supported on the displacement spiral 13. For this purpose, it is provided that the bearing bush 26 is recessed for the eccentric bearing 12 in the positive displacement spiral 13. The bearing bush 26 dips into the counter-spiral 14 and protrudes into the counter-spiral 14. The bottom of the bearing bush 26, on which the spring 16 is supported, is at the same height as the inner edges of the turns of the displacer spiral 13. This is well in FIG. 3 to recognize (open position). In the closed position according to FIG. 4 Therefore, the bottom of the bearing bush 26 abuts against the counter-spiral 14 and seals the innermost gas chamber between the displacement spiral 13 and the counter-spiral 14.

To the counter-spiral 14 from the in FIG. 3 Open position shown in the in FIG. 4 To show shown closed position, a piston 17, in particular an annular piston 17 is provided which is coaxial with the longitudinal axis of the counter-coil 14 slidably. Instead of the annular piston 17, a plurality of arranged on the circumference of the counter-spiral 14 cylindrical piston can be provided. The annular piston 17 engages the rear wall 21 of the counter-spiral 14 and acts on it with a closing force which operates against the spring force of the spring 16.

The piston 17 engages, as in the FIGS. 1 to 4 to recognize, in addition to the pressure chamber 15 to the counter-coil 14 at. The piston 17 is thus arranged outside the pressure chamber 15 or generally eccentrically. For the fluid connection between the counter-spiral 14 and the pressure chamber 15, therefore, a simple outlet opening may be formed in the counter-spiral 14 (not shown).

The annular piston 17 has a pressure ring 47, which is connected to a bottom 48 of the piston. The piston head 48 is axially displaceable and pressure-tight in an axial guide 18. The axial guide 18 is formed as an annular chamber. For the actuation of the annular piston 17, the annular chamber is connected to a supply connection 20c. As in FIG. 1 illustrated, the supply port 20c is connected to a 2/3-way valve, which in turn is connected to a high pressure port 20a and a suction pressure port 20b, so that the annular chamber can be acted upon alternately with high pressure or suction pressure. As a result, the counter-spiral 14 can be alternately moved back and forth between the open position or the closed position. In this case, the annular piston 17 operates substantially only against the spring force of the spring 16, because the pressure prevailing in the pressure chamber 15 and acting on the counter-spiral 14 pressure is at least partially compensated by the pressure acting between the counter-spiral 14 and the displacement spiral 13 during compression. In addition, only relatively small strokes are required to adjust the pressure equalizing gap 41. For example, stroke ranges of about 0.3 to 0.7 mm, in particular a stroke of about 0.5 mm.

The power control takes place in the scroll compressor by switching on or off the compressor power, specifically by changing the frequency of the cyclic or alternating movement of the counter-spiral 14th

The compressed gas collected in the pressure chamber 15 flows through an outlet 49 from the pressure chamber 15 into an oil separator 29, which in the present case is designed as a cyclone separator. The compressed gas flows through the oil separator 29 and a check valve 19 in the circuit of the air conditioner. The check valve 19, which prevents the compressed gas from flowing back into the scroll compressor which is switched off, is designed, for example, for pressure differences of 0.5 to 1 bar.

The sealing of the displacement spiral 13 against the counter-spiral 14 in the axial direction is assisted by the fact that a high pressure is applied to a rear wall 25 of the displacement spiral. For this purpose, a receiving space 24, also referred to as a backpressure space ( FIG. 1 ), in which a part of the counterweight 28 and the eccentric bearing 12 are arranged, fluidly connected to the high pressure side. The receiving space 24 is bounded by the rear wall 25 of the compressor spiral 13 and the housing intermediate wall 32.

The receiving space 24 is fluid-tightly separated from the suction space 33 by the second shaft seal 37 described above. A sealing and sliding ring 52 is disposed between the displacement spiral 13 and the housing intermediate wall 32 and seals the receiving space 24 from the high pressure side. The sealing and sliding ring 52 is seated in an annular groove in the housing intermediate wall 32. Between the housing intermediate wall 32 and the displacement spiral 13, a gap is formed (not shown). The displacement spiral 13 is therefore not supported in the axial direction directly on the housing intermediate wall 32 but on the sealing and sliding ring 52 and slides on this. The sealing and sliding ring 52 protrudes from the annular groove and seals the gap. The gap can be about 0.2 mm to 0.5 mm wide.

For connection to the high pressure side, a line 50 connects the oil separator 29 with the receiving space 24. This extends through the housing cover 31, the counter-spiral 14 and the intermediate wall 32. Between the oil separator 29 and the receiving space 24, specifically between the counter-spiral 14 and the Housing cover 31, a pressure reducer 53 is arranged, which ensures that between the high pressure side and the receiving space 24, a pressure difference of about 10% -20% prevails. This ensures that in the closed position of the axial contact pressure between the displacement spiral 13 and the counter-spiral 14 and thus the axial tightness is increased.
In thermal terms, the in FIG. 1 shown scroll compressor optimized so that an undesirable heating of the refrigerant vapor is reduced on the suction side. For this purpose, the pressure chamber 15 is encapsulated (s. FIG. 4 ). Incidentally, the pressure chamber 15 is free of installation. For example, the pressure chamber may have an inner shell 51, in particular made of stainless steel or stainless steel. The inner shell 51 has a lower thermal conductivity than aluminum. In addition, the thermal insulation of the oil separator 29 reduces the heating of the refrigerant vapor on the suction side. Again, the thermal insulation is carried out by an encapsulation, for example by an inner shell stainless steel or stainless steel surrounding the cyclone separator. Further, the pressure reducer 53 is isolated by encapsulation with an inner shell of stainless steel or stainless steel.

This makes it possible to manufacture the housing cover 31, for example made of aluminum, without fear of excessive heat transfer from the high-pressure side to the suction side.

The only difference between the scroll compressor according to FIG. 5 and the scroll compressor according to FIG. 1 consists in that instead of the mechanical drive, an electric drive with a constant, that is, temporally immutable speed is used. Incidentally, reference is made to the statements in connection with the mechanically driven scroll compressor.

The advantages of the scroll compressor according to the invention are in the FIGS. 6 to 8 shown. FIG. 6 Figure 11 is a graph showing the mass inertia of the entire scroll compressor in kgmm ² , with the prior art 1500 kgmm ² left gray column representing the invention and the right white pillar the invention. The invention leads to an improvement of the mass inertia by a factor of 3. Since the displacement spiral 13 rotates in the off state, the inertia when connecting the scroll compressor is virtually zero. In contrast, the effective inertia when connecting a compressor of the prior art is up to 300 kgmm ² . The resulting switch-on monument for the engine is in FIG. 8 The left-hand diagram shows the torque peak in a motor known from the prior art and the right-hand diagram shows the torque curve when switching on a scroll compressor according to the invention.

LIST OF REFERENCE NUMBERS

10

drive

11

drive shaft

12

eccentric position

13

Verdrängerspirale

14

against spiral

15

pressure chamber

16

feather

17

Piston / ring piston

18

piston guide

19

check valve

20a

High pressure port

20b

Saugdruckanschluss

20c

supply terminal

21

Rear wall counter-spiral

22

flange

23

inner wall

24

accommodation space

25

Rear wall displacement spiral

26

bearing bush

27

recess

28

counterweight

29

oil separator

30

Weight

31

housing cover

32

Housing partition

33

suction

34

caseback

35

takeaway

36

first shaft seal

37

second shaft seal

38

eccentric

39

guide pins

40

guide bores

41

Pressure compensation gap

42

sliding surface

43

seal

44

wall

45

attack

46

central recess

47

compression ring

48

piston crown

49

outlet

50

management

51

interior Skin

52

Sliding and sealing ring

53

pressure reducer

Claims (15)

1. A scroll compressor for a CO₂ vehicle air conditioning system having a drive (10) which is connected by means of a drive shaft (11) to an eccentric bearing (12), and having a movable displacement spiral (13) which is rotatably connected to the eccentric bearing (12) and which engages into a counterpart spiral (14) such that, between the displacement spiral (13) and the counterpart spiral (14), radially inwardly travelling chambers are formed in order to compress the refrigerant and discharge it into a pressure chamber (15),
   characterized in that
   the drive (10) is a mechanical drive or an electric drive with a fixed rotational speed, and the counterpart spiral (14) is movable in an alternating manner relative to the displacement spiral (13) in an axial direction, wherein, between the counterpart spiral (14) and the displacement spiral (13), there is arranged at least one spring (16) for exerting an axial release force on the counterpart spiral (14), and at least one piston (17), adjacent to the pressure chamber (15), engages on the counterpart spiral (14), in order to exert an axial closing force on the latter.
2. The scroll compressor according to Claim 1,
   characterized in that
   the spring (16) is arranged opposite the pressure chamber (15).
3. The scroll compressor according to Claim 1 or 2,
   characterized in that
   the piston (17) comprises an annular piston which is arranged so as to be displaceable coaxially with respect to the counterpart spiral (14).
4. The scroll compressor according to one of Claims 1 to 3,
   characterized in that
   the piston (17) is mounted in a piston guide (18) which can be connected to a high-pressure side and to a suction side of the scroll compressor in an alternating manner.
5. The scroll compressor according to one of Claims 1 to 4,
   characterized in that
   a check valve (19) is positioned downstream of the pressure chamber (15) in the flow direction.
6. The scroll compressor according to Claim 5,
   characterized in that
   the connection (20) for the connecting of the piston guide (18) to the high-pressure side is arranged between the pressure chamber (15) and the check valve (19).
7. The scroll compressor according to one of Claims 1 to 6,
   characterized in that
   a rear wall (21), arranged on the high-pressure side, of the counterpart spiral (14) forms the base of the pressure chamber (15) and has a flange (22) which lies in an axially movable manner against an inner wall (23) of the pressure chamber (15).
8. The scroll compressor according to one of Claims 1 to 7,
   characterized in that
   a receiving space (24), which is closed off with respect to the suction side, for the eccentric bearing (12) is fluidically connected to the pressure chamber (15), and a rear wall (25) of the displacement spiral (13) can be acted on with a contact pressure.
9. The scroll compressor according to one of Claims 1 to 8,
   characterized in that
   the distance between the central point of the counterpart spiral (14) and the central point of the displacement spiral (13) is at most 1.5 mm, in particular at most 1.2 mm, in particular at most 1.0 mm, in particular at most 0.8 mm, in particular at most 0.6 mm, in particular at most 0.4 mm, in particular at most 0.2 mm.
10. The scroll compressor according to one of Claims 1 to 9,
    characterized in that
    the counterpart spiral (14) has a winding angle of 660° to 720°, in particular 680° to 700°.
11. The scroll compressor according to one of Claims 1 to 10,
    characterized in that
    the mass moment of inertia of the scroll compressor is at most 500 kgmm².
12. The scroll compressor according to one of Claims 1 to 11,
    characterized in that
    the eccentric bearing (12) is arranged in the displacement chamber between the displacement spiral (13) and the counterpart spiral (14) and has a bearing bushing (26) which is formed in one piece with the displacement spiral (13) and the base (54) of which is in alignment with the face side of the windings of the displacement spiral (13).
13. The scroll compressor according to one of Claims 1 to 12,
    characterized in that
    the displacement spiral (13) has a central recess (27) in which there is at least partially received a counterweight (28) which is connected to the eccentric bearing (12).
14. The scroll compressor according to one of Claims 1 to 13,
    characterized in that
    the volume of the pressure chamber (15) is greater by a factor of 5-7, in particular by a factor of 6, than the suction volume per revolution of the displacement spiral (13), and/or the pressure chamber (15) is thermally insulated.
15. A vehicle air conditioning system that contains CO₂ as refrigerant, having a scroll compressor according to Claim 1.

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