PRESSURE REDUCER FOR ROTARY INTERNAL COMBUSTION ENGINE

Abstract

A pressure reducer for a rotary internal combustion engine comprises a housing (1) accommodating a first shaft (6) and a second shaft (8) running parallel to each other through the housing (1), and a first rotor (7) on the first shaft (6) and a second rotor (9) on the second shaft (8). The first rotor (7) and the second rotor (9) are configured in a meshing arrangement, when the first shaft (6) and the second shaft (8) rotate in counter direction to each other. The first rotor (6) comprises several radial extensions (10) having convex shaped outer flanks (11), and the second rotor (9) comprises several radial wings (13) defining indentations (14) between two wings (13) having a concave shaped surface (15). A pressure expansion chamber (17) is defined by a volume between a convex shaped flank (11a) of an extension (10a) of the first rotor (7) and a concave shaped surface (15a) of an indentation (14a) of the second rotor (9), such that an outer tip (12a) of the radial extension (10a) abuts on the concave shaped surface (15a) of the indentation (14a) and an outer edge (16a) of the indentation (14a) abuts on the convex shaped flank (11a) of the extension (10a). In rotation the tip (12a) slides over the concave surface (15a) of the indentation (14a) and the edge (16a) of the indentation (14a) slides along the convex flank (11a), thereby expanding the volume of the pressure expansion chamber (17).

Claims

1. A pressure reducer for a rotary internal combustion engine comprising: a housing accommodating a first shaft and a second shaft running parallel to each other through the housing, a first rotor on the first shaft and a second rotor on the second shaft, wherein the first rotor and the second rotor are configured in a meshing arrangement, when the first shaft and the second shaft rotate in counter direction to each other, the first rotor comprising several radial extensions having non-circular convex shaped outer flanks, and the second rotor comprising several radial wings defining indentations between two wings having a non-circular concave shaped surface, wherein said first and second rotors are arranged in said housing and the non-circular convex shaped outer flanks and non-circular concave shaped surface of the extensions and indentations are configured in such a way that, upon meshing of a said extension in a said indentation a pressure expansion chamber is defined between a convex shaped flank said extension of the first rotor and a concave shaped surface of said indentation of the second rotor, said convex shaped flank of said extension and said concave shaped surface said indentation contacting each other simultaneously upon meshing at only two distinct contact points at an outer tip of the radial extension on the concave shaped surface on the one end and at an outer edge of the indentation on the convex shaped flank of the extension the other end.

2. The pressure reducer according to claim 1, wherein the housing comprises an inlet opening culminating in an inlet chamber defined by a convex flank of the first rotor, a concave surface of the second rotor and a first inner surface of the housing.

3. The pressure reducer according to claim 1, wherein on the opposite side of the inlet opening the housing comprises an outlet opening out of an outlet chamber defined by a convex flank of the first rotor and a concave surface of the second rotor and a second inner surface of the housing opposing the first inner surface.

4. The pressure reducer according to claim 1, wherein the housing has a first portion of at least half cylindrical shape housing the first rotor and a second portion of at least half cylindrical shape housing the second rotor, wherein the first portion and the second portion are connected.

5. The pressure reducer according to claim 1, wherein the number of indentations on the second rotor is larger than the number of extensions on the first rotor.

6. The pressure reducer according to claim 1, wherein the first shaft and the second shaft are designed to rotate with different velocity.

7. The pressure reducer according to claim 1, wherein the abutting concave surfaces and convex flanks are lubricated.

8. The pressure reducer according to claim 1, wherein meshing toothed wheels are fixed on the first shaft and on the second shaft for synchronizing the revolting movement of the shafts.

9. A rotary internal combustion engine comprising the pressure reducer according to claim 1.

10. The rotary internal combustion engine according to claim 9, wherein the inlet chamber is connected to a combustion chamber of the engine.

Description

APPENDED DRAWINGS

[0020] FIG. 1 a schematic cross section of a pressure reducer according to the invention, and

[0021] FIG. 2 a three-dimensional view of the pressure reducer shown in FIG. 1.

DESCRIPTION OF A PREFERRED EXAMPLE OF THE INVENTION

[0022] FIG. 1 shows a cross-sectional view of a pressure reducer according to the invention. The pressure reducer comprises a housing 1 with a first half cylindrically shaped portion 2 and a second half cylindrically shaped portion 3. The portions 2 and 3 of the housing 1 are connected, although in FIG. 1 they are depicted unconnected due to an inlet opening 4 into the housing and an outlet opening 5 out of the housing.

[0023] The first half cylindrically shaped portion 2 of the housing 1 accommodates a first shaft 6 carrying a first rotor 7. The second half cylindrically shaped portion 3 accommodates a second shaft 8 carrying a second rotor 9. The shafts run parallel through the housing 1 and can be supported by bearings in opposing walls of the housing 1.

[0024] The first rotor 7 comprises several radial extensions or lobes 10. In the shown example the rotor 7 has four extensions 10. The extensions or lobes 10 have non-circular, elliptical or ovoidal, convex shaped outer flanks 11 extending from a central mounting hub of the rotor 7 on shaft 6, said elliptically shaped flanks 11 joining radially in to form an outer tip 12 of each extensions or lobes 10.

[0025] The second rotor 9 comprises several radial wings 13 extending from a central mounting hub of the second rotor 9 on shaft 8. In the shown example the rotor 9 has six radial wings 13. The wings 13 define indentations or grooves 14 between each other. The indentations or grooves 14 are designed with a non-circular, elliptical or ovoidal, concave shaped surface 15. The wings 13 terminate in edges 16 at their radially outer most points.

[0026] The first shaft 6 and the second shaft 8 are distanced in the housing 1 and the radial extensions 10 of the first rotor and the indentations 14 of the second rotor 1 are respectively configured in such a way that said extensions 10 mesh in the indentations 14 in a non-mating fashion, i.e. the radius or curvature of the flanks 11 differ from that of the inner surface of the grooves or indentations 14, more specifically the radius or curvature of the flanks 11 is larger than that of the inner surface 15 of the grooves or indentations 14 such that, as represented in FIG. 1, a pressure expansion chamber 17 is established upon meshing of an extension 10a in an indentation or groove 14a between a flank 11a of said extension 10a and the inner surface 15a of said indentation or groove 14a. Upon meshing, the outer tip 12a of the radial extension 10a abuts at a first point on the concave shaped surface 15a of the indentation 14a, while an outer edge 16a of the indentation 14a abuts at a second point different from said first point on the convex shaped flank 11a of the extension 10a, defining a croissant-shaped inner volume forming the expansion chamber 17 between said extension 10a of the first rotor 7 and concave surface 15a of the indentation 14a.

[0027] In rotation the tip 12a slides over the concave surface 15a of the indentation 14a and the edge 16a of the indentation 14a slides along the convex flank 11a, while the shafts 6 and rotate in counter direction. At the beginning the tip 12a contacts the concave surface 15a shortly behind the edge 16a.

[0028] With continuing rotation of the shafts, the tip 12a slides down the concave surface 15a. Simultaneously the edge 16a slides along the convex flank 11a from the tip 12a to the bottom of the flank. In other words, the outer flank 11a of an extension 10a of the first rotor 7 and the inner concave surface 15a of a corresponding indention 14a of the second rotor 9 are contacting each other simultaneously during a meshing engagement of the rotor 7, 9 at only two distinct contact points at said outer tip 12a of the radial extension 10a on the concave shaped surface 15a on the one end and at the outer edge 16a of the indentation 14a on the convex shaped flank 11a of the extension 10a on the other end. Thereby an expansion chamber 17 is permanently defined and arranged therebetween, the volume of which varies upon rotation of the rotors 7, 9 until disengagement of the extension 10a with the indentation 14a.

[0029] Accordingly, as opposed to prior art expanders, the meshing between rotors 7, 9 never results in either a continuous linear contact or a single contact point between mating surfaces of the extensions 10 of the first rotor 7 and corresponding indentations 14 of the second rotor 9. This specific configuration of the rotors 7, 9 of the pressure expander of the invention and relative movement in operation results in expanding the volume of the pressure expansion chamber 17 upon rotation in opposite directions of the rotors 7, 9.

[0030] The inlet opening 4 of the housing 1 culminates in an inlet chamber 18, which is defined by a convex flank 11 of the first rotor 7, a concave surface 15 of the second rotor 9 and a first inner surface 19 of the housing. On the opposite side of the inlet opening 4, i.e. at the outlet opening 5 the housing 1 comprises an outlet chamber 20 defined by a convex flank 11 of the first rotor 7, a concave surface 15 of the second rotor 9 and a second inner surface 21 of the housing 1 on the opposite side of the first inner surface 19.

[0031] In operation gas enters the inlet opening 4 into inlet chamber 18. The revolution of the shafts 7 and 9 moves the convex flank 11 towards the concave surface 15, which define the inlet chamber 18 towards each other until the tip 12 abuts on the concave surface 15 and traps the gas in the pressure expansion chamber 17. Continuing revolution enlarges the volume of the pressure expansion chamber 17 and the gas inside the chamber expands. Further rotation of the shafts 7 and 9 results in an opening of the pressure expansion chamber 17 and a release of the gas into the outlet chamber 20. From there the expanded gas can be emptied out of the housing 1 via the outlet opening 5. Continued rotation of the rotors 7 and 9 allows a constant gas flow through the housing and a continuous expansion of the gas.

[0032] The inlet opening is connected to a rotary internal combustion engine (not shown). The use of the pressure reducer as described for FIG. 1 facilitates the expansion of the combustion gas generated during the combustion cycle of the engine.

[0033] FIG. 2 shows a three-dimensional semi-transparent view of the housing 1 of the pressure reducer according to the invention. The first shaft 6 carrying the first rotor 7 and the second shaft 8 carrying the second rotor 9 are supported in bearings 30. The inlet opening 4 of the housing 1 is located at the same axial position than the rotors 7 and 9. The housing accommodating the shafts 6 and 8 and the rotors 7 and 9 represents a compact construction unit for the rotary internal combustion engine that is made up of only a few parts and can be produced at low costs. Further the unit can be easily exchanged and/or maintained.

[0034] As mentioned before the bearings 30 may comprise means for reducing a pressure exerted on the first shaft 6 and the second shaft 8 during operation of the rotary internal combustion engine. For example ball bearings may be arranged between the housing 1 and each of the shafts 6 and 8. Other means for reducing the pressure on the shafts are known to a person skilled in the art, like for example an advantageous static construction of the housing and the shafts. The pressure reducing means helps to decrease the pressure exerted on the shafts 6 and 8 during the process of expanding the volume of the pressure expansion chamber 17.

REFERENCE SIGNS USED IN THE APPENDED DRAWINGS

[0035] 1 housing [0036] 2 first cylindrical portion [0037] 3 second cylindrical portion [0038] 4 inlet opening [0039] 5 outlet opening [0040] 6 first shaft [0041] 7 first rotor [0042] 8 second shaft [0043] 9 second rotor [0044] 10, 10a extension [0045] 11, 11a convex flank [0046] 12, 12a tip [0047] 13 wing [0048] 14, 14a indentation [0049] 15, 15a concave surface [0050] 16, 16a edge [0051] 17 pressure expansion chamber [0052] 18 inlet chamber [0053] 19 first inner surface [0054] 20 outlet chamber [0055] 21 second inner surface [0056] 30 bearing