SCROLL COMPRESSOR FOR GENERATING OIL-FREE COMPRESSED AIR

Abstract

A scroll compressor for generating oil-free compressed air, in particular for a compressed air brake system of a lorry, with a drive which is arranged in a housing and is connected to an orbiting displacer scroll which has a displacer scroll bottom and a displacer scroll. The displacer scroll wall engages into a stationary mating scroll, with the result that at least one variable compression chamber is formed between the displacer scroll and the mating scroll. A seal element is provided between the displacer scroll and the housing wherein the seal element is fastened in the displacer scroll bottom and seals against a sliding plate which is connected fixedly to the housing. A compressed air brake system with a scroll compressor of this type.

Claims

1-14. (canceled)

15. A scroll compressor for generating oil-free compressed air comprising: a drive arranged in a housing and connected with one or more orbiting displacer scrolls, each displacer scroll having a displacer scroll bottom and a displacer scroll wall, wherein the displacer scroll wall engages into one or more stationary mating scrolls, so that at least one variable compression chamber is formed between a respective displacer scroll and a respective mating scroll, wherein a seal element is provided between the respective displacer scroll and the housing, and wherein the seal element is fastened in a respective displacer scroll bottom and seals against a sliding plate fixedly connected with the housing.

16. The scroll compressor according to claim 15, wherein the sliding plate has a harder material than the housing, at least on a contact area with the seal element.

17. The scroll compressor according to claim 15, wherein a scraping element for stripping oil residues from the sliding plate is fastened in each displacer scroll bottom.

18. The scroll compressor according to claim 17, wherein the respective displacer scroll bottom has a seal groove for receiving the seal element and a scraper groove for receiving the scraping element.

19. The scroll compressor according to claim 17, wherein a sliding element is configured and arranged between the respective displacer scroll and the sliding plate.

20. The scroll compressor according to claim 19, wherein the sliding element is arranged radially inside of the seal element and the scraping element.

21. The scroll compressor according to claim 15, wherein guide pins are anchored in the housing and extend through openings in the sliding plate into guide rings configured and arranged in the displacer scroll bottom, wherein each guide pin has a ledge that projects over a respective sliding plate, so that a distance exists between a respective guide ring and the sliding plate.

22. The scroll compressor according to claim 15, wherein the drive is configured and arranged between a first displacer scroll and a second displacer scroll.

23. The scroll compressor according to claim 22, wherein the drive has a shaft including a first shaft end connected with the first displacer scroll and a second shaft end connected with the second displacer scroll.

24. The scroll compressor according to claim 22, wherein the first displacer scroll forms a first compressor stage with a first mating scroll, and wherein the second displacer scroll forms a second compressor stage with a second mating scroll.

25. The scroll compressor according to claim 15, wherein one or more scroll seals is provided between the displacer scroll wall and the respective mating scroll, as well as between a mating scroll wall and the respective displacer scroll.

26. The scroll compressor according to claim 25, wherein a first scroll seal is configured and arranged in a first scroll groove of the displacer scroll wall that is arranged to open toward the respective mating scroll, and wherein a second scroll seal is configured and arranged in a second scroll groove of the mating scroll wall that is arranged to open toward the respective displacer scroll.

27. The scroll compressor according to claim 15, wherein the drive, the housing, and the respective mating scroll are cooled by water.

28. A compressed air brake system comprising: a scroll compressor configured to generate oil-free compressed air, the scroll compressor including a drive arranged in a housing and connected with one or more orbiting displacer scrolls, each displacer scroll having a displacer scroll bottom and a displacer scroll wall, wherein the displacer scroll wall engages into one or more stationary mating scrolls, so that at least one variable compression chamber is formed between a respective displacer scroll and a respective mating scroll, wherein a seal element is provided between the respective displacer scroll and the housing, and wherein the seal element is fastened in the displacer scroll bottom and seals against a sliding plate fixedly connected with the housing.

29. A vehicle having an air brake system comprising: a scroll compressor configured to generate oil-free compressed air, the scroll compressor including a drive arranged in a housing and connected with one or more orbiting displacer scrolls, each displacer scroll having a displacer scroll bottom and a displacer scroll wall, wherein the displacer scroll wall engages into one or more stationary mating scrolls, so that at least one variable compression chamber is formed between a respective displacer scroll and a respective mating scroll, wherein a seal element is provided between the respective displacer scroll and the housing, and wherein the seal element is fastened in the displacer scroll bottom and seals against a sliding plate fixedly connected with the housing.

Description

[0030] FIG. 1 a cross sectional view through a scroll compressor according to the invention based on a preferred exemplary embodiment;

[0031] FIG. 2 a detail C of the scroll compressor according to FIG. 1;

[0032] FIG. 3 a front view of the scroll compressor according to FIG. 1; and

[0033] FIG. 4 a sectional view of the scroll compressor according to FIG. 1 along line E-E on FIG. 3.

[0034] The scroll compressor according to FIG. 1 is designed as a two-stage compressor. For this purpose, the scroll compressor has a central drive segment 1, which is axially connected on both sides to a respective compressor segment 2, 3. A first compressor segment 2 is here designed as a first compressor stage, and the second compressor segment 3 as a second compressor stage. The first compressor segment 2 serves to compress an ambient air pressure to a medium air pressure, wherein the second compressor segment 3 compresses the medium air pressure to a high air pressure.

[0035] The drive segment 1 comprises the drive 10, which comprises an electric motor 11 and a shaft 12. The electric motor 11 is arranged inside of a housing 4, which is multipart in design for ease of maintenance. The housing 4 comprises a drive housing 20, two bearing housings 23, 24 that connect to the drive housing 20, mating scrolls 21, 22 that likewise form parts of the housing 4, and end covers 5, 6. As a consequence, a first bearing housing 23 connects to the drive housing 20 in the direction of the first compressor segment 2. The first bearing housing 23 is fixedly connected with the first mating scroll 21, which likewise forms part of the housing 4. The first mating scroll 21 is followed by the first end cover 5, which axially closes the housing 4. A second bearing housing 24 is arranged on the opposite side of the drive housing 20, and connected with a second mating scroll 22. The second mating scroll 22 is long axially covered by a second end cover 6.

[0036] The shaft 12 is mounted in the drive housing 20 by shaft bearings 15. The shaft 12 has a first shaft end 13, which is directed toward the first compressor segment 2. Further provided is a second shaft end 14, which faces the second compressor segment 3. Both shaft ends 13, 14 each have an eccentric pin 16, which is arranged in an eccentric bearing 17 that establishes the connection to the respective displacer scroll 31, 32. Therefore, the first displacer scroll 31 is mounted on the eccentric pin 16 of the first shaft end 13 via the eccentric bearing 17. The second displacer scroll 32 is mounted on the eccentric pin 16 of the second shaft end 14 via the eccentric bearing 17.

[0037] The displacer scrolls 31, 32 each have a displacer scroll bottom 39, from which a displacer scroll wall 38 extends into the respective mating scroll 21, 22. This will be exemplarily explained below based on FIG. 2, which shows a cutout of the second compressor segment 3 of the scroll compressor according to FIG. 1. The design described below for the first compressor segment 2 applies analogously to the second compressor segment 3. The first displacer scroll 31 and the second displacer scroll 32 as well as the first mating scroll 21 and the second mating scroll 22 are thus similarly constructed, in particular also with regard to their arrangement relative to each other. They only differ in terms of the volume of a compression chamber 30 formed between them, which in the second compressor stage, meaning between the second displacer scroll 32 and the second mating scroll 22, is smaller than in the first compressor stage, i.e., between the first displacer scroll 31 and the first mating scroll 21.

[0038] Therefore, FIG. 2 shows the first displacer scroll 31, which comprises a displacer scroll bottom 39 and a displacer scroll wall 38. The first displacer scroll 31 engages into the first mating scroll 21, so that the compression chamber 30 is formed between the displacer scroll wall 38 and a mating scroll wall 28. The compression chamber 30 is variable, meaning that the orbiting motion of the first displacer scroll 31 changes the volume of the compression chamber 30, thereby performing a compression of the gas located in the compression chamber 30, preferably air.

[0039] In order to effectively seal the first displacer scroll 31 and the first mating scroll 21 against each other, it is provided that the first displacer scroll 31 and the first mating scroll 21 each have a scroll groove 19, in which a scroll seal 18 is arranged. The scroll seal 18 of the first displacer scroll 31 here forms a seal against a mating scroll bottom 29 of the first mating scroll 21. By contrast, the scroll seal 18 of the first mating scroll 21 forms a seal against the displacer scroll bottom 39. The scroll seals can each comprise thrust washers, which are arranged between the respective scroll groove 19 and the displacer scroll bottom 39 or the mating scroll bottom 29.

[0040] In order to guide the first displacer scroll 31 into the orbiting motion, several guide rings 37 are arranged in the displacer scroll bottom 39. The guide rings 37 accommodate guide pins 25, which are fixed in the first bearing housing 23. Each guide pin 25 comprises an anchoring section 25a, which is held in a corresponding hole of the first bearing housing 23. A guide section 25b of the guide pin 25 engages into the guide ring 37. A ledge 25c is formed between the guide section 25b and the anchoring section 25a. In particular, the ledge 25c is formed by virtue of the guide section 25b having a smaller diameter than the anchoring section 25a.

[0041] The anchoring section 25a is preferably not completely recessed into the corresponding hole of the first bearing housing 23. Rather, the ledge 25c of the anchoring section 25a protrudes over the first bearing housing 23. The guide ring 37 rests on the ledge 25c. Since the ledge 25c protrudes over the first bearing housing 23, a distance is formed between the guide ring 37 and a sliding plate 26 that is fixed in the first bearing housing 23. As a result, oil that lubricates the drive segment can flow between the guide ring 37 and the sliding plate 26, and thereby lubricate the sliding plate 26.

[0042] The sliding plate 26 is preferably ring-shaped in design, and comprises through holes through which the guide pins 25 can extend. The sliding plate 26 can be sealed with a ring seal 27 on a side facing the first bearing housing 23. The ring seal 27 is here arranged in a continuous groove in the first bearing housing 23.

[0043] The first displacer scroll 31 rests on the sliding plate 26 with a sliding element 36. Specifically, a sliding element 36 in the form of a sliding ring is provided radially inside of the guide pins 25, and arranged in a groove in the displacer scroll bottom 29. The sliding element 36 can protrude slightly over the displacer scroll bottom 39, so that essentially only the sliding element 36 slides on the sliding plate 26. As a consequence, the displacer scroll bottom 39 is spaced a distance apart from the sliding plate 26. The sliding element 36 preferably also serves as an axial bearing for the first displacer scroll 31. The sliding element 36 is here lubricated with liquid, preferably lubricated with oil. In general, the shaft bearings 15 can also be lubricated with oil. However, it is also possible that the shaft bearings 15 be lubricated with grease.

[0044] A sealing system is provided to prevent oil from getting out of the drive segment 1 and into the first compressor segment 2. The sealing system comprises a seal element 33 and a scraping element 34. The seal element 33 and the scraping element 34 are each ring-shaped in design, and fastened in corresponding ring grooves in the first displacer scroll 31. As evident on FIG. 2, a respective preloading element 35 is arranged in the ring grooves that hold the scraping element 34 or the seal element 33. The preloading element 35 is arranged between the seal element 33 or the scraping element 34 and a groove bottom of the respective groove in the displacer scroll bottom 39, and pushes the seal element 33 or the scraping element 34 against the sliding plate 25. The scraping element 34 here serves to strip away oil that accumulates on the sliding plate 26. The seal element 33 prevents any oil that might not have been stripped away from getting into the area flooded with compressed air, in particular the compression chamber 30.

[0045] FIG. 3 shows a front view of the scroll compressor, in particular the second end cover 6. The first end cover 5 is preferably identical in design, making it possible to reduce production costs.

[0046] The respective end cover 5, 6 comprises several fastening holes 42, which are arranged regularly distributed over the circumference of the end cover 5, 6. The fastening holes make it possible to fix the end cover 5, 6 on the respective mating scroll 21, 22, for example by means of screws.

[0047] Each end cover 5, 6 further has an air inlet 7 and an air outlet 8. The air inlet 7 is connected with an entrance area of the compression chamber 30. The air outlet 8 is connected with an exit area of the compression chamber 30. Cooling ports 9 are further provided on the end cover 5, 6 so that the scroll compressor can be cooled with water. The cooling ports 9 make it possible to hook up a cooling water pump, so as to form a closed cooling water circuit inside of the housing 4.

[0048] FIG. 4 shows a section through the scroll compressor along the E-E line on FIG. 3. The section hence does not run along a straight line as a cross section through the scroll compressor, for example like the cross section according to FIG. 1. Given the special sectional progression along the E-E line, the air inlet 7 can thus also be discerned on FIG. 4 in the area of the first compressor segment 2, while it cannot be seen in the cross sectional view according to FIG. 1.

[0049] The sectional view according to FIG. 4 is intended to illustrate how the two compressor stages or compressor segments 2, 3 interact with each other. It is provided that the first compressor segment 2 perform a precompression of the air flowing into the compression chamber 30 of the first compressor segment 2 via the air inlet 7 in the first end cover 5. The air is initially compressed to a medium air pressure in the first compressor segment 2, and transferred to a compressed air line 40 via the air outlet 8 in the first end cover 5.

[0050] The air is strongly heated by the compression in the first compressor segment 2. In order to prevent the scroll compressor from becoming overheated, it is additionally provided for purposes of water cooling via the cooling ports 9 that the pre-compressed medium pressure air be guided via a heat exchanger 41. For this reason, the heat exchanger 41 is provided in the compressed air line 40, so as to extract heat from the medium pressure air and transfer it to another fluid circuit, which can be filled with gas or liquid.

[0051] The medium pressure air cooled in this way then passes through the air inlet 7 in the second end cover 6 and into the compression chamber 30 of the second compressor segment 3. As evident on FIG. 4, the compression chamber 30 of the second compressor segment 3 has a smaller volume than the compression chamber 30 of the first compressor segment 2, so as to further compress the medium pressure air to a high-pressure air. The high-pressure air exits the second compressor segment 3 via the air outlet 8 in the second end cover 6, which is preferably connected with a compressed air brake system of a lorry.

[0052] Specifically, the scroll compressor can be configured in such a way that air with an air pressure of 1 bar applied to the air inlet 7 of the first end cover 5 be pre-compressed in the first compressor segment 2 (first compressor stage) to a medium air pressure of between 3.5 and 4 bar, and post-compressed in the second compressor segment 3 (second compressor stage) to a high air pressure of about 14 bar. Before being fed into the second compressor segment 3, the medium pressure air with a medium air pressure of 3.5 to 4 bar is guided via the compressed air line 40 to the heat exchanger 41, and there cooled to prevent the second compressor segment 3 from overheating.

REFERENCE LIST

[0053] 1 Drive segment [0054] 2 First compressor segment [0055] 3 Second compressor segment [0056] 4 Housing [0057] 5 First end cover [0058] 6 Second end cover [0059] 7 Air inlet [0060] 8 Air outlet [0061] 9 Cooling port [0062] 10 Drive [0063] 11 Electric motor [0064] 12 Shaft [0065] 13 First shaft end [0066] 14 Second shaft end [0067] 15 Shaft bearing [0068] 16 Eccentric pin [0069] 17 Eccentric bearing [0070] 18 Scroll seal [0071] 19 Scroll groove [0072] 20 Drive housing [0073] 21 First mating scroll [0074] 22 Second mating scroll [0075] 23 First bearing housing [0076] 24 Second bearing housing [0077] 25 Guide pin [0078] 25a Anchoring section [0079] 25b Guide section [0080] 25c Ledge [0081] 26 Sliding plate [0082] 27 Ring seal [0083] 28 Mating scroll wall [0084] 29 Mating scroll bottom [0085] 30 Compression chamber [0086] 31 First displacer scroll [0087] 32 Second displacer scroll [0088] 33 Seal element [0089] 34 Scraping element [0090] 35 Pre-loading element [0091] 36 Sliding element [0092] 37 Guide ring [0093] 38 Displacer scroll wall [0094] 39 Displacer scroll bottom [0095] 40 Compressed air line [0096] 41 Heat exchanger [0097] 42 Fastening hole