Rotary Piston Machine and Method for Producing a Seal in a Rotary Piston Machine

Abstract

A rotary piston engine and a method for manufacturing a sealing in a rotary piston engine are described. The rotary piston engine has at least two piston pairs respectively connected via a link, the pistons of which are arranged at opposite ends of the links and, during operation, circulate on an at least approximately circular path in a piston housing, such that varying working volumes are enclosed between the pistons of different piston pairs during the circulation and that, via a sealing provided between the piston housing and the pistons, a fluid flow between the enclosed working volumes is at least impeded. The technical solution described is characterized in that the sealing is formed by a gap between the pistons and the piston housing and surfaces of the pistons and the piston housing delimiting the gap at least at times are irregularly structured.

Claims

1.-20. (canceled)

21. A rotary piston engine (1) with at least two piston pairs (2) respectively connected via a link (4), the pistons (3) of which are arranged at opposite ends of the links (4) and, during operation, circulate on an at least approximately circular path in a piston housing (5), such that varying working volumes (7) are enclosed between the pistons (3) of different piston pairs (2) during the circulation, and with a sealing (6) provided between the piston housing (5) and the pistons (3), which at least impedes a fluid flow between the enclosed working volumes, characterized in that the sealing (6) is formed by a gap (8) between the pistons (3) and the piston housing (5), in which no sealing elements are arranged, and that the gap (8) is designed such that leakage flows between neighboring working spaces are minimized, wherein surfaces (9, 10) of the pistons (3) and of the piston housing (5) delimiting the gap (8) at least at times have a surface structure generated directly upon commissioning by means of a running-in or grinding-in, resp., process.

22. The rotary piston engine according to claim 21, characterized in that a gap height of the gap (8) between the pistons (3) and the piston housing (5) is chosen such that a mean distance between opposing surfaces (9, 10) of the pistons (3) and of the piston housing (5) lies in a range of 0.02 and 0.14 mm.

23. The rotary piston engine according to claim 21, characterized in that a gap height of the gap (8) between the pistons (3) and the piston housing (5) is chosen such that a mean distance between opposing surfaces (9, 10) of the pistons (3) and of the piston housing (5) lies in a range of 0.05 and 0.08 mm.

24. The rotary piston engine according to claim 21, characterized in that a gap height of the gap (8) between the pistons (3) and the piston housing (5) is chosen such that a mean distance between opposing surfaces (9, 10) of the pistons (3) and of the piston housing (5) does not exceed 0.15 mm at nominal operating speed.

25. The rotary piston engine according to claim 21, characterized in that the pistons (3) comprise a material, at least in the area of the surfaces (9, 10) delimiting the gap (8), which differs from a material, which the piston housing (5) comprises at least in the area of the surfaces (9, 10) delimiting the gap (8)

26. The rotary piston engine according to claim 25, characterized in that, in the area of the surface (9) delimiting the gap (8), the pistons (3) comprise a harder material than the piston housing (5) in the area of the surface (10) delimiting the gap (8).

27. The rotary piston engine according to claim 21, characterized in that the surfaces (9, 10) of the pistons (3) and/or of the piston housing (5) delimiting the gap (8) at least at times comprise a coating at least in sections.

28. The rotary piston engine according claim 21, characterized in that the surfaces (9) of the pistons (3) delimiting the gap (8) comprise an oxidic protective layer at least in sections.

29. The rotary piston engine according to claim 21, characterized in that the piston housing (5), at least in the area of the surface (10) delimiting the gap (8), comprises a synthetic material, a copper alloy with a zinc content no higher than 40% by weight, an alloy with a copper content of more than 60% by weight, or cast iron.

30. The rotary piston engine according to claim 21, characterized in that the piston housing (5), at least in the area of the surface (10) delimiting the gap (8), comprises red brass.

31. The rotary piston engine according to claim 21, characterized in that the surfaces (9, 10) delimiting the gap (8) have been structured by a grinding-in process, in which the opposing surfaces (9, 10) of the pistons (3) as well as of the piston housing (5) are brought into contact at least at times during a circular movement of the pistons (3) in their installed position in the piston housing (5).

32. The rotary piston engine according to claim 21, characterized in that a ratio of an average height of a piston (3) in the radial direction to a width of the piston (3) in the axial direction is 2:1.

33. The rotary piston engine according to claim 21, characterized in that the piston pairs (2) are connected with at least partially internal planetary gears (11).

34. The rotary piston engine according to claim 32, characterized in that the piston pairs (2) are at least indirectly connected with a planet wheel (13) of the planetary gears (11) via at least one piston rod connection (12).

35. The rotary piston engine according to claim 21, characterized in that the pistons (3) comprise at least one hollow space in their interior.

36. The rotary piston engine according to claim 21, characterized in that a height of the gap (8) between at least one of the pistons (3) and the piston housing (5) varies in the axial direction.

37. The rotary piston engine according to claim 35, characterized in that the height of the gap (8) between the piston (3) and the piston housing (5) in the axial direction reaches a minimum at a center (14) of the surface (9) of the piston (3).

38. The rotary piston engine according to claim 21, characterized in that a gap between two housings of gears connected with the rotary pistons and/or between one housing of gears connected with the rotary pistons and the piston housing (5) is sealed with at least one contact seal.

39. The rotary piston engine according to claim 21, characterized in that a gap between two housings of gears connected with the rotary pistons and/or between one housing of gears connected with the rotary pistons and the piston housing (5) is sealed with a labyrinth seal with labyrinth passages in mesh.

40. A method for manufacturing an at least partial sealing (6) of a gap (8) between a piston housing (5) of a rotary piston engine (1) and at least one piston (3), which, during operation, circulates on an at least approximately circular path in the piston housing (5), in which components of the rotary piston engine (1) are produced and assembled such that surfaces (9, 10) of the piston (3) and of the piston housing (5) touch at least in sections during the circulation of the piston (3) in the piston housing (5), and in which surfaces (9, 10) delimiting the gap (8) are structured at least in sections during a grinding-in process subsequent to commissioning of the rotary piston engine (1).

41. The method according to claim 40, characterized in that, during the grinding-in process, a relative movement between piston (3) and piston housing (5) is initiated in the axial direction of the rotary piston engine (1) at least at times.

42. The method according to claim 40, characterized in that the grinding-in process is performed at the nominal operating speed of the rotary piston engine (1) at least at times.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Hereinafter, the invention is set forth in more detail on the basis of special embodiments and referring to the figures, without restriction of the general idea of the invention, in which:

[0030] FIG. 1: is a view of a piston housing of a rotary piston engine with pistons rotatably mounted therein;

[0031] FIG. 2: is a perspective view of a piston pair;

[0032] FIG. 3: is a top and cross-sectional view of a piston pair; as well as

[0033] FIG. 4: is a cross-sectional view of a rotary piston engine with a sealing between the rotatably mounted pistons and the piston housing designed according to the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] FIG. 1 shows a piston housing 5 of a rotary piston engine 1 with pistons 3 rotatably mounted therein. Two piston pairs 2 are provided, wherein the pistons 3 are respectively arranged at the ends of links 4 of the piston pairs 2. During operation of the rotary piston engine 1, the pistons 3 circulate on a circular path, such that a different volume 7, a so-called working volume, is respectively enclosed between the pistons 3 of the different piston pairs 2. In this manner, four equivalent working volumes are realized in the embodiment shown. Thus, upon operation of the rotary piston engine 1, the individual operating points alternate in a cyclical fashion.

[0035] Here, driving of the pistons 3 takes place via a driveshaft 15, which is connected with the pistons 3 or the piston pairs 2, resp., via planetary gears 11. Via respective inlets 16 and outlets 17, a working medium, preferably air, flows into the working spaces and is alternatingly compressed and expanded, wherein the working volumes 7 alter respectively. Due to heat dissipation carried out in the meantime, the depicted rotary piston engine 1 according to the embodiment described here can be used as a cooling unit for providing cooling air. In an advantageous manner, in this case, air is used as the working or cooling medium, resp.

[0036] In order to minimize leakage flows between the neighboring working volumes 7 at least to a large extent, a sealing 6 is provided between the surfaces 9, 10 of the pistons 3 and of the piston housing 5. According to the embodiment shown, the sealing is realized by a gap 8, wherein the surfaces 9, 10 delimiting the gap 8 are irregularly structured. The mean gap height, i.e., the vertical distance between the surfaces 9, 10 delimiting the gap 8, at a rotational movement of the pistons with 600 rpm is max. 0.12 mm.

[0037] The surfaces 9, 10 in the area of the gaps 8 comprise a structuring, which has been generated during a grinding-in process immediately upon commissioning of the rotary piston engine 1. This grinding-in process and the respective structuring of the surfaces 9, 10 delimiting the gap takes place immediately after assembly of the rotary piston engine 1, in particular of the piston pairs 2 in the piston housing 5. In that, no additional sealing elements are provided.

[0038] FIG. 2 shows a piston pair 2 in a perspective view, as it is used in a rotary piston engine 1 designed according to the invention. In such a rotary piston engine 1, two of these piston pairs 2 are arranged such that the pistons 3 engage with one another offset from one another. Upon a rotation, i.e., a circulation on a circular path, the pistons 3 enclose a varying working volume 7 located in the working spaces between them.

[0039] The outer delimiting surfaces 9 of the pistons 3 in the radial direction have a special shape. This is made visible in FIG. 2 with the edge depicted. While the pistons have a radius 18 at their outer flank, the outer delimiting surface 9 of the pistons 3 in the axial direction respectively has a slight incline from outside towards the center 14. Due to this design of the outer delimiting surfaces or shell surfaces 9, resp., of the piston 3, a particularly process-reliable grinding-in process of the piston surfaces as well as, above all, of the piston housing surfaces can be realized. A structuring of the surface of the pistons and/or of the piston housing achieved by the grinding-in process preferably can be achieved with a simultaneous relative movement between piston and piston housing.

[0040] In addition, FIG. 3 shows a top view as well as a cross-sectional view of a piston pair 2 designed according to the invention. In the cross-sectional view “B-B”, once again, the design of the external delimiting surface 9 of the piston 3 circumferential in the radial direction can be clearly seen. Clearly recognizable is the inclination of the surface 9 between the center 14 of the surface 9 and the outer edges. The outer edges of the pistons 3 in turn have a curve 8. The two pistons 3 of the depicted piston pair 2 are connected with one another via a link 4 and rotate jointly upon operation of a rotary piston engine 1. The surfaces 9 of the pistons, which in the installed position delimit a gap 8 together with surfaces 10 of a piston housing 5, are in turn structured in a suitable manner, wherein the structuring has been generated by means of a grinding-in process, in which the surface of the pistons 3 has been brought into contact with the surface 10 of the piston housing 5 at least in sections.

[0041] FIG. 4 shows a rotary piston engine 1 with a piston housing 5 in a cross-sectional view, in which housing two piston pairs 2, of which one is depicted in this view, are rotatably mounted. Driving of the rotary piston engine 1, which is preferably used as a cooling unit, takes place via a centrally mounted driveshaft 15. From the driveshaft 15, power and torque are first transmitted onto planetary gears 11, and then from these onto the piston pairs 2 or the pistons 3, resp. Via a piston rod connection 12, the pistons 3 are in operative connection with the planet wheels 13 of the planetary gears 11.

[0042] Essential to the invention is the sealing 6 between the surfaces 9, 10 of the pistons 3 and of the piston housing 5. With the sealing 6, it is ensured that leakage flows between the individual working volumes 7 is minimized and thus the efficiency of the respectively designed rotary piston engine 1 is maximized. Between the surfaces 9 of the pistons 3 and the surface 10 of the piston housing, a continuous gap 8 is provided, which moves with the pistons during the rotation of the pistons 3 within the piston housing 5. The sealing 6 is achieved with suitable dimensioning of the gap 8 as well as structuring of the surfaces 9, 10 of the pistons 3 as well as of the piston housing 5. It is essential that the surface 9 of the pistons 3 is designed more wear-resistant than the surface 10 of the piston housing 5.

[0043] During a grinding-in process immediately after commissioning of the rotary piston engine 1, the surfaces 9, 10, in particular the surface 10 of the piston housing 5, are structured such that leakage flows between the individual working volumes 7 are minimized. In the embodiment depicted in FIG. 4, the pistons 3 are manufactured from aluminum, wherein the outer surfaces 9 are provided with an oxide protective layer by means of an eloxal process. The surface 10 of the piston housing 5, on the other hand, comprises brass, which compared to the surface 9 of the pistons 3 is soft and not wear-resistant in the same manner, so that during the grinding-in process, a special structure is ground-in, in particular into the surface 10 of the piston housing 5, which is complementary to the surface structure of the surface 9 of the moving pistons 3 opposite at least at times. Therefore, in particular the surface 10 of the piston housing 5 comprises a suitable structuring, so that the gap 8 between the piston surfaces 9 and the housing surface 10 is designed comparatively narrow.

LIST OF REFERENCE NUMERALS

[0044] 1 Rotary piston engine [0045] 2 Piston pair [0046] 3 Pistons [0047] 4 Link [0048] 5 Piston housing [0049] 6 Sealing [0050] 7 Working volume [0051] 8 Gap [0052] 9 Piston surface [0053] 10 Piston housing surface [0054] 11 Planetary gears [0055] 12 Piston rod connection [0056] 13 Planet wheel [0057] 14 Center of the circumferentially outer piston surface [0058] 15 Driveshaft [0059] 16 Inlet [0060] 17 Outlet [0061] 18 Radius