DISPLACEMENT MACHINE ACCORDING TO THE SPIRAL PRINCIPLE, METHOD FOR OPERATING A DISPLACEMENT MACHINE, VEHICLE AIR-CONDITIONING SYSTEM, AND VEHICLE

Abstract

The invention relates to a displacement machine according to the spiral principle, in particular a scroll compressor or scroll expander, with a high-pressure chamber, a low-pressure chamber and an orbiting displacement spiral, which engages in a counter-spiral such that chambers are formed between the displacement spiral and the counter-spiral for receiving a working medium, wherein a counter-pressure chamber is formed between the low-pressure chamber and the displacement spiral. According to the invention a pressure regulating device which is fluidically connected to the counter-pressure chamber sets a pressure difference between the counter-pressure chamber and the low-pressure chamber by means of a set value specified by the computing unit.

Claims

1. A displacement machine according to the spiral principle, in particular a scroll compressor or scroll expander, with a high-pressure chamber, a low-pressure chamber and an orbiting displacement spiral, which engages in a counter-spiral such that chambers are formed between the displacement spiral and the counter-spiral for receiving a working medium, wherein a counter-pressure chamber is formed between the low-pressure chamber and the displacement spiral, wherein a pressure regulating device which is fluidically connected to the counter-pressure chamber sets a pressure difference between the counter-pressure chamber and the low-pressure chamber by means of a set value specified by the computing unit, and wherein the working medium is CO.sub.2 and/or R134a and/or R1234yf and/or butane and/or ethanol and/or cyclopentan.

2. The displacement machine according to claim 1, wherein radially inward migrating chambers are formed between the displacement spiral and the counter-spiral, in order to suck in a working medium, in particular a refrigerant, from the low-pressure chamber, to compress it and to eject it into the high-pressure chamber.

3. The displacement machine according to claim 1, wherein radially outward migrating chambers are formed between the displacement spiral and the counter-spiral, in order to receive a working medium, in particular a working fluid, from the high-pressure chamber, to expand it and push it out into the low-pressure chamber.

4. The displacement machine according to claim 1, wherein the pressure regulating device comprises an electrically controllable regulating valve and a throttle.

5. The displacement machine according to claim 4, wherein the electrically controllable regulating valve fluidically connects the counter-pressure chamber with the high-pressure chamber or the low-pressure chamber.

6. The displacement machine according to claim 4, wherein the electrically controllable regulating valve includes a movable valve needle, which can be electrically activated.

7. The displacement machine according to claim 4, wherein the electrically controllable regulating valve fluidically connects the counter-pressure chamber to the low-pressure chamber, wherein the throttle is arranged between the high-pressure chamber and the counter-pressure chamber.

8. The displacement machine according to claim 4, wherein the electrically controllable regulating valve fluidically connects the high-pressure chamber and the counter-pressure chamber, wherein the throttle is arranged between the counter-pressure chamber and the low-pressure chamber.

9. The displacement machine according to claim 1, wherein the displacement spiral is movable in axial direction relative to the counter-spiral.

10. The displacement machine according to claim 9, wherein a contact pressure effective in axial direction from the displacement spiral onto the counter-spiral can be adjusted by the pressure prevailing in the counter-pressure chamber.

11. The displacement machine according to claim 1, wherein the displacement machine is configured as an electrically driven displacement machine and/or a displacement machine driven by an electric motor or as a displacement machine with mechanical drive.

12. A displacement machine according to the spiral principle, in particular a scroll compressor or scroll expander, with a high-pressure chamber, a low-pressure chamber and an orbiting displacement spiral, which engages in a counter-spiral such that chambers are formed between the displacement spiral and the counter-spiral for receiving a working medium, wherein a counter-pressure chamber is formed between the low-pressure chamber and the displacement spiral, and wherein a pressure-regulating device is in fluid connection with a counter-pressure chamber, which pressure-regulating device, by means of a set value specified by the computing unit, sets a pressure difference between the counter-pressure chamber and the low-pressure chamber.

13. A method for operating a displacement machine, in particular a displacement machine according to claim 1, comprising a) ascertaining a pressure value P.sub.D in a high-pressure section of the displacement machine or in a high-pressure section of a system, in which the displacement machine has been installed, b) forwarding the ascertained pressure value P.sub.D to a computing unit, c) determining a differential pressure value ? P.sub.BP between a counter-pressure P.sub.BP prevailing in a counter-pressure chamber and a low-pressure P.sub.S prevailing in a low-pressure chamber by way of a characteristic line and/or a characteristic field with the aid of the pressure value P.sub.D, wherein the characteristic line and/or a characteristic field is stored in the computing unit, and d) controlling a pressure regulating device, in particular an electrically controllable regulating valve, by means of a control current applied to a magnetic coil and autonomously adjusting the differential pressure value ? P.sub.BP by means of the electric regulating valve.

14. The method for operating a displacement machine, in particular a displacement machine according to claim 1, comprising: a) ascertaining a pressure value P.sub.D in a high-pressure section of the displacement machine or a high-pressure section of a system, in which the displacement machine has been installed, and a pressure value P.sub.S in a low-pressure chamber of the displacement machine, b) forwarding the ascertained pressure values P.sub.D and P.sub.S to a computing unit, c) determining a differential pressure value ? P.sub.BP between the counter-pressure P.sub.BP in a counter-pressure chamber and the low pressure P.sub.S in the low-pressure chamber by way of a characteristic line and/or a characteristic field with the aid of the ascertained pressure values P.sub.D and P.sub.S, wherein the characteristic line and/or a characteristic field is stored in the computing unit, and d) controlling a pressure regulating device, in particular an electrically controllable regulating valve, by means of a control current applied to a magnetic coil and autonomously adjusting the differential pressure value ? P.sub.BP by means of the electric regulating valve.

15. The method according to claim 13, wherein when controlling the pressure regulating device, in particular the electrically controllable regulating valve, the determined differential pressure value ? P.sub.BP is associated with an electrical amperage for activating a valve element, in particular a valve needle, which is arranged in a magnetic coil.

16. The method according to claim 15, wherein the magnetic coil of the pressure-regulating device, in particular the electrically controllable regulating valve, is acted upon by the electrical amperage, so that an electromagnetic force acting on the valve needle is set.

17. A vehicle conditioning system, in particular with a scroll compressor, according to claim 1.

18. The vehicle air-conditioning system according to claim 17, wherein the vehicle air-conditioning system contains CO.sub.2 and/or R134a and/or R1234yf and/o butane and/or ethanol and/or water as refrigerant.

19. A vehicle, in particular a hybrid vehicle, with a displacement machine according to claim 1 and/or with a vehicle air-conditioning system according to claim 17.

20. The vehicle, in particular a lorry, with a displacement machine, in particular with a scroll expander, according to claim 1.

Description

[0049] The invention will now be explained in detail by way of exemplary embodiments with reference to the attached schematic drawings, in which

[0050] FIG. 1 shows a longitudinal section through a displacement machine according to the invention, in particular a scroll compressor according to a first embodiment;

[0051] FIG. 2 shows a longitudinal section through a displacement machine according to the invention, in particular a scroll compressor according to a second embodiment;

[0052] FIG. 3 a longitudinal section through an electrically controllable regulating valve; and

[0053] FIG. 4 show a principal view regarding a first embodiment of a method according to the invention for operating a displacement machine.

[0054] Two embodiments of a displacement machine according to the invention will now be explained, wherein the embodiments shown represent scroll compressors. It is pointed out that the displacement machine according to the invention may also be configured and operated as a scroll expander.

[0055] Identical parts and parts having the same function are marked with the same reference symbols.

[0056] The scroll compressor 10 described in detail in conjunction with FIG. 1 and FIG. 2 may, for example, be used as a compressor in a vehicle air-conditioning system. A vehicle air-conditioning system such as a CO.sub.2 vehicle air-conditioning system typically comprises a gas cooler, an inner heat exchanger, a throttle, an evaporator and a compressor. The compressor may thus be the scroll compressor 10 which is depicted. In other words the scroll compressor 10 is a displacement machine according to the spiral principle.

[0057] The scroll compressor 10 depicted comprises a mechanical drive 11 in the form of a belt pulley. In use the belt pulley is connected to an electric motor or a combustion engine. Alternatively it is possible for the scroll compressor 10 to be driven electrically or by an electric motor.

[0058] Moreover the scroll compressor 10 comprises a housing 20 with an upper housing part 21, which closes the high-pressure side of the scroll compressor. In the housing 20 a housing partition 22 is formed which limits a low-pressure chamber 30. The low-pressure chamber 30 may also be called a suction chamber. A through-opening through which a drive shaft extends is formed in the housing floor 23. The shaft end 13 arranged outside the housing 20 is non-rotatably connected to a follower 14, which engages in the belt pulley rotatably mounted on the housing 20, so that a torque can be transferred from the belt pulley to the drive shaft 12.

[0059] The drive shaft 12 is rotatably mounted, on the one side, in the housing floor 23 and on the other side, in the housing partition 22. Sealing of the drive shaft 12 against the housing floor 23 is effected by a first shaft seal 24 and, against the housing partition 22, is effected by a second shaft seal 25.

[0060] The scroll compressor 10 further comprises a movable, in particular orbiting, displacement spiral 31 and a counter-spiral 32. The displacement spiral 31 and the counter spiral 32 engage with each other. The counter-spiral 32 is preferably stationary both in circumferential direction and in radial direction. The movable displacement spiral 31 coupled to the drive shaft 12 describes a circular path, so that due to this movement a number of gas pockets or gas chambers are created in a manner known as such, which migrate radially inwardly between the displacement spiral 31 and the counter-spiral 32. This orbiting movement causes the working medium, in particular the refrigerant, to be sucked in and to be compressed by the further spiral movement and the associated reduction of the gas chamber. The working medium, in particular the refrigerant, is radially compressed from the outside to the inside, for example in a linearly increasing manner, and ejected into the high-pressure chamber 40 in the centre of the counter-spiral 32.

[0061] In order to generate an orbiting movement of the displacement spiral 31, an eccentric bearing 26 is formed, which is connected to the drive shaft 12 by means of an eccentric pin 27. The eccentric bearing 26 and the displacement spiral 31 are arranged eccentrically relative to the counter-spiral 32. The gas chambers are separated from one another in a pressure-tight manner due to the fact that the displacement spiral 31 is supported against the counter-spiral 32. The radial contact pressure between the displacement spiral 31 and the counter-spiral 32 is achieved by the eccentricity.

[0062] The rotational movement of the displacement spiral 31 can for example be avoided by providing guide pins and guide bores.

[0063] The scroll compressors shown in FIGS. 1 and 2 are without a coupling. Nevertheless, in order to be able to vary the output of the compressor, the scroll compressor can be connected and disconnected. To this end it is provided that the displacement spiral 31 is movable in axial direction, i.e. in a direction parallel to the drive shaft 12. This allows the displacement spiral 31 to be moved in direction of the counter-spiral 32. Provided that the displacement spiral 31 does not rest on the counter-spiral 32, an open position of the scroll compressor 10 is formed. In this open position a pressure-equalisation gap is formed between the displacement spiral 31 and the counter-spiral 32, which connects the gas chambers, which in radial direction are separated from each other, between the displacement spiral 31 and the counter-spiral 32. This pressure equalisation gap formed in such a way as to allow compressed gas to flow radially outwards from the chambers arranged further inwards, so that an equalisation of pressure takes place. The output of the scroll compressor 10 is thereby reduced to zero or at least approximately to zero.

[0064] The counter-spiral 32 is arranged downstream of the high-pressure chamber 40 in flow direction and is fluidically connected to the counter-spiral 32 by an outlet not shown. The outlet is preferably not exactly arranged in the centre of the counter-spiral 32, but is located away from the centre in the area of the innermost chamber between the displacement spiral 31 and the counter-spiral 32. As a result the outlet of the bearing bushing 28 of the eccentric bearing 26 is not covered and the finally compressed working medium, in particular the finally compressed refrigerant, can be ejected into the high-pressure chamber 40.

[0065] The back wall 33 of the counter-spiral 32, in sections, forms the floor of the high-pressure chamber 40. The back wall 33 is wider than the high-pressure chamber 40. The high-pressure chamber 40 is laterally limited by the side wall 41. A recess 42, in which a gasket 43 is arranged, is formed in one end of the side wall 41 pointing to the back wall 33 of the counter-spiral 32. The side wall 41 is a circumferential wall, which forms a stop for the counter-spiral 32. The high-pressure chamber 40 is formed in the upper housing part 21. This has a rotationally symmetric cross-section.

[0066] The compressed working medium which has collected in the high-pressure 40 flows through an outlet 44 from the high-pressure chamber 40 into an oil separator 45, which in this case is configured as a cyclone separator. The compressed working medium, in particular the compressed refrigerant, flows through the oil separator 45 and the opening 46 into the circular flow of the exemplary air-conditioning system.

[0067] Axial guidance of the displacement spiral 31 in direction of the counter-spiral 32 or in the opposite direction is realised in that a back wall 34 of the displacement spiral 31 is acted upon by an appropriate pressure. To this end the counter-pressure chamber 50, which could also be called the back-pressure chamber, is fluidically connected with the high-pressure side of the scroll compressor 10, in particular the high-pressure chamber 40. The eccentric bearing 26 is located in the counter-pressure chamber 50.

[0068] The counter-pressure chamber 50 is limited by the back wall 34 of the displacement spiral 31 and by the housing partition 22.

[0069] The counter-pressure chamber 50 is separated in a fluid-tight manner from the low-pressure chamber 30 by the already described second shaft seal 25. A sealing and gliding ring 29 sits in an annular groove in the housing partition 22. A gap (not shown) is formed between the housing partition 22 and the displacement spiral 31. Therefore the displacement spiral 31 does not support itself directly in axial direction against the housing partition 22, but against the sealing and gliding ring 29 and glides on the same.

[0070] The explanations given up to now refer to a scroll compressor 10, both as regards the embodiment shown in FIG. 1 and the embodiment depicted in FIG. 2.

[0071] FIG. 1 also shows that a pressure regulating device 60 is fluidically connected to the counter-pressure chamber 50. With the aid of the pressure regulating device 60 a pressure difference can be determined between the counter-pressure chamber 50 and the low-pressure chamber 30. The pressure regulating device 60 comprises an electrically controllable regulating valve 61. The electrically controllable regulating valve 61 establishes a fluid connection between the counter-pressure chamber 50 and the low-pressure chamber 30. The electrically controllable regulating valve 61 is shown in detail in FIG. 3.

[0072] The throttle 62 is arranged between the high-pressure chamber 40 and the counter-pressure chamber 50. The pressure regulating unit 60 thus includes the throttle 62 and the electrically controllable regulating valve 61. The counter-pressure chamber 50 is connected to the high-pressure side, in particular to the high-pressure chamber 40, of the scroll compressor 10. The counter-pressure chamber 50 is connected to the oil separator 45 via a first line section 51 and a second line section 52. The throttle 62 is formed between the first line section 51 and the second line section 52. The first line section 51 is formed in the housing 20, in particular in the upper housing part 21. The second line section 52 is also formed section-wise in the housing 20, in particular in the circumferential wall 15.

[0073] The last portion of the second line section, i.e. the portion of the second line section 52 which ends in the counter-pressure chamber 50, is formed as a through-passage in the housing partition 22. With the aid of the working medium in the counter-pressure chamber 50, in particular as a function from the pressure prevailing therein, the displacement spiral 31 can be axially moved in direction of the counter spiral 32. The contact pressure acting in axial direction from the displacement spiral 31 onto the counter spiral 32 can be adjusted by the pressure prevailing in the counter-pressure chamber 50.

[0074] The regulating valve 61 is additionally provided for this purpose. This is also formed in the circumferential wall 15 of the housing 20. A first discharge section 53 is in turn formed in the housing partition 22. The first discharge section 53 ends in the electrically controllable regulating valve 61 by means of a line section formed in the circumferential wall 15. The circumferential wall 15 also has a second discharge section 54 formed in it, which establishes a connection between the regulating valve 61 and the low-pressure chamber 30.

[0075] In order to regulate the pressure prevailing in the counter-pressure chamber 50 and/or in order to set variable operating points for the pressure in the counter-pressure chamber 50, the pressure value P.sub.D is initially ascertained in the high-pressure section of the scroll compressor 10, in particular in the high-pressure chamber 40. This value is then forwarded to a computing unit. By means of the ascertained pressure value P.sub.D a differential pressure value ? P.sub.BP is determined, which is effective between the counter-pressure P.sub.BP in the counter-pressure chamber 50 and the low pressure P.sub.S in the low-pressure chamber 30. This is preferably done by way of a characteristic line and/or a characteristic field using the ascertained pressure value P.sub.D. The characteristic line and/or the characteristic field is stored in the computing unit.

[0076] The pressure regulating device 60, in particular the electrically controllable regulating valve 61 is thereupon controlled by way of the determined differential pressure value ? P.sub.BP. This is done applying a control current to the magnetic coil 63 of the regulating valve 61.

[0077] The determined differential pressure value ? P.sub.BP is associated with an electric amperage for controlling the valve element 61 so that an electromagnetic force can be set which acts on the valve needle 64.

[0078] The valve needle 64 is impacted by both a spring force originating from a spring (see FIG. 3) and the force/pressure of the counter-pressure chamber 50, as well as the force/pressure of the low-pressure chamber 30. In addition the electromagnetic force generated by the magnetic coil 63 also impacts the valve needle 64.

[0079] The control current acting on the magnetic coil 63 establishes an electromagnetic force, which counteracts the pressure of the counter-pressure chamber 50 and the pressure of the low-pressure chamber 30. The regulating valve 61 regulates itself independently due to an equalised pressure balance/a force equilibrium. In order to achieve an equalised force balance, the valve 61 regulates independently the pressure of the counter-pressure chamber 50 as a function of the force/the pressure prevailing in the low-pressure chamber 30. To this end a through-opening cross-section/a annular surface is set between the valve needle 64 and the housing 65 (see FIG. 3).

[0080] FIG. 2 shows as further embodiment of a scroll compressor 10. This scroll compressor 10 also comprises a pressure regulating device 60. The pressure regulating device 60 also comprises a regulating valve 61 and a throttle 62. The electrically controllable regulating valve 61 establishes a fluid connection between the high-pressure side, in particular the high-pressure chamber 40, and the counter-pressure chamber 50. The fluid connection between the high-pressure chamber 40 and the counter-pressure chamber 50 passes indirectly through the oil separator 45.

[0081] To this end a first line section 71 is formed in the vicinity of the opening 46. This is formed in the upper housing part 21. There follows a second line section 72 which is formed in the circumferential wall 15 of the housing 20. The counter-pressure chamber 50 can be supplied via the regulating valve 61 with a working medium, in particular a refrigerant, which flows via the oil separator 45 from the high-pressure chamber 40 into the counter-pressure chamber 50.

[0082] A feed line 73 is formed in the housing partition 22 between the regulating valve 61 and the counter-pressure chamber 50. The throttle 62, on the other hand, is formed between the low-pressure chamber 30 and the counter-pressure chamber 50. A discharge section 74 is formed between the counter-pressure chamber 50 and the throttle 62. The fluid connection between the counter-pressure chamber 50 and the low-pressure chamber 30 passes through the discharge section 74 as well as the throttle 62.

[0083] This embodiment of the invention also allows a pressure difference to be adjusted between the counter-pressure chamber 50 and the low-pressure chamber 30. To this end a pressure value P.sub.D, in particular a high-pressure value, is ascertained in the high-pressure section of the scroll compressor 10, in particular in the high-pressure chamber 40 of the scroll compressor 10. In addition the pressure value, in particular low pressure P.sub.S, is ascertained in the low-pressure section, in particular in the low-pressure chamber 30 of the scroll compressor 10. These two values are forwarded to a computing unit. The differential pressure value ? P.sub.BP between the counter-pressure P.sub.BP in the counter-pressure chamber 50 and the low pressure P.sub.S in the low-pressure chamber 30 can again be ascertained by way of a characteristic line with the aid of ascertained pressure values. To this end the characteristic line or a characteristic field is stored in the computing unit.

[0084] Then follows activation of the pressure regulating device 60, in particular the electrically controllable regulating valve 61 in that a control current is applied to the magnetic coil 63. In this case the valve needle 64 of the regulating valve 64 is impacted by the spring force, the pressure P.sub.BP/the force of the counter-pressure chamber 50, as well as the pressure P.sub.D/the force of the high-pressure chamber 40 and the electromagnetic force generated by the magnetic coil 63. The differential pressure value ? P.sub.BP may be set by setting a through-opening cross-section between the valve needle 64 and the housing 65 of the regulating valve 61. In this way a flow cross-section is automatically set by the regulating valve 61 between the high pressure P.sub.BP in the high-pressure chamber 40 and the counter-pressure P.sub.BP of the counter-pressure chamber 50.

[0085] FIG. 3 shows a regulating valve 61, in particular a regulating valve 61 as required in the embodiment of FIG. 1. A valve needle 64 is formed in the regulating valve 61. This figure also shows the spring 66, the force of which acts on the valve needle 64. The valve needle 64 is arranged within a magnetic coil 63. A current can be applied to the magnetic coil 63 via the feed lines 67, so that depending on the control current flowing through the feed lines 67 to the magnetic coil 63 an electromagnetic force acts on the valve needle 64, which is adjustable.

[0086] The broken lines indicate that the regulating valve 61 comprises a feed line to the counter-pressure chamber 50 and to the low-pressure chamber 30.

[0087] The top 69 of the valve needle 64 may be supported against a housing section 65 such that an annular gap 68 is formed between the housing 65 and the top 69. The pressure difference ? P.sub.BP between the counter-pressure chamber 50 and the low-pressure chamber 30 can be set in dependence of the size of this annular gap 68.

[0088] The counter-pressure in the counter-pressure chamber 50 is P.sub.BP, whereas a low pressure P.sub.S prevails in the low-pressure chamber 30.

[0089] FIG. 4 depicts the method required in relation to the embodiment as per FIG. 1.

[0090] As shown, a pressure P.sub.D of 100 bar prevails in the high-pressure chamber 40. This pressure is measured and read by, or forwarded to, a computing unit. The pressure of 100 bar is reduced to 45 bar by the throttle 45, so that a working medium flowing from the high-pressure chamber 40 into the counter-pressure chamber 50, has a pressure P.sub.BP of 45 bar when in the counter-pressure chamber 50.

[0091] The regulating valve 61 is arranged between the counter-pressure chamber 50 and the low-pressure chamber 30. The regulating valve 61 is a mechanically self-regulating valve, wherein the magnetic coil in the regulating valve 61 (not shown here) is controlled by the computing unit. For this purpose the computing unit 80 determines a differential pressure value ? P.sub.BP, wherein each differential pressure value ? P.sub.BP has a control current I associated with it, so that by means of the pressure value P.sub.D and the characteristic field 81 stored in the computing unit 80 a control current I in respect of the magnetic coil is ascertained.

[0092] The computing unit 80 forwards the value of the control current I to the magnetic coil of the regulating valve 61. Due to the control current I the magnetic coil of the valve element 61 is subjected to an electric amperage, so that an electromagnetic force can be set which acts on the valve needle 64.

REFERENCE LIST

[0093] 10 scroll compressor [0094] 11 mechanical drive [0095] 12 drive shaft [0096] 13 shaft end [0097] 14 follower [0098] 15 circumferential wall [0099] 20 housing [0100] 21 upper housing part [0101] 22 housing partition [0102] 23 housing floor [0103] 24 first shaft seal [0104] 25 second shaft seal [0105] 26 eccentric bearing [0106] 27 eccentric pin [0107] 28 bearing bushing [0108] 29 sealing and gliding ring [0109] 30 low-pressure chamber [0110] 31 displacement spiral [0111] 32 counter-spiral [0112] 33 back wall of counter-spiral [0113] 34 back wall of displacement spiral [0114] 40 high-pressure chamber [0115] 41 side wall [0116] 42 recess [0117] 43 gasket [0118] 44 outlet [0119] 45 oil separator [0120] 46 opening [0121] 50 counter-pressure chamber [0122] 51 first line section [0123] 52 second line section [0124] 53 first discharge section [0125] 54 second discharge section [0126] 60 pressure regulating device [0127] 61 regulating valve [0128] 62 throttle [0129] 63 magnetic coil [0130] 64 valve needle [0131] 65 housing [0132] 66 spring [0133] 67 feed line [0134] 68 annular gap [0135] 69 top [0136] 71 first line section [0137] 72 second line section [0138] 73 feed line [0139] 74 discharge section [0140] 80 computing unit [0141] 81 characteristic field [0142] I control current [0143] P.sub.D pressure in the high-pressure section [0144] P.sub.S pressure in the low-pressure section [0145] P.sub.BP counter-pressure [0146] ? P.sub.BP differential pressure value