US3102520A - Multi-part rotor for rotary mechanisms - Google Patents

Description

p 3, 1963 I K. SCHLOR 3,102,520

MULTI-PART RO'VIQR FOR ROTARY MECHANISMS 2 Sheets-Sheet 1 Filed March 7, 1962 INVENTOR. KARL EEHLUR 724971144 [like/7064 1 ATTORNEY Sept. 3, 1963 K. scHLOR 3,102,520

MULTI-PART ROTOR FOR ROTARY MECHANISMS Filed March 7', 1962 2 Shasta-Sheet 2 INVENTOR. KARL EEHLEIR ATTORNEY United States Patent 3 102 520 MULTI-PART ROTGR I OR ROTARY li llilfil-lANlSh is Karl Schliir, Lochham, near-Munich, Germany, assignor to NSU Motorenwerke Alrtiengeselischaft, Neckarsulm,

The present invention relates broadly to the art of rotary mechanisms, and is particularly directed to the inner body or rotor of such mechanisms.

The invention is particularly useful in connection with rotary mechanisms similar to that disclosed in US. Patent No. 2,988,065, although as will become apparent this invention is not limited to this specific type of rotary mechanism. Rotary engines of this type are especially useful as fluid motors, fluid pumps and internal cornbustion engines. In the following description the invention is described in relation to an internal combustion engine but the invention is also suitable to fluid pumps and fluid motors.

A rotary mechanism as disclosed in said p-atent icomprises an outer body having a cavity therein and an inner body or rotor disposed therein rotatable relative to the outer body, about an axis laterally spaced from but parallel to the axis of said cavity. The inner body is journaled on an eccentric portion of a shaft which is co-axial with the outer body and journaled in bearings carried by the outer body end walls. The outer body has axiallyspaced end walls and a peripheral Wall interconnecting the end walls to form said cavity; the inner surface of the cavity peripheral wall having a multi-lobe profile which preferably is basically an epitrochoid. The inner body has end faces disposed adjacent to said outer body end walls for sealing cooperation therewith and has a periphenal surface with a plurality of circumferentially-spaced apex portions, each carrying a radially-movable seal for sealing engagement with the multi-lobe inner surface of the outer body peripheral wall to form a plurality of working chambers between the two bodies which vary in volume upon relative rotation of the two bodies. The inner body or rotor of such a rotary combustion engine is subjected to very high thermal stresses, and the removal of heat from the rotor is a major difiiculty with such engines. The use of a cooling medium circulated through the rotor to remove the heat is a known method of cooling the rotor. But the devices and means to circulate a fiuid to and from the rotor complicate the engine design. When a cooling medium is not circulated through the rotor, the heat must be transmitted, mostly by conduction, from the rotor to the outer body. This creates a danger that the rotor bearing on the eccentric portion of the shaft may become overheated and impaired. Similarly the rotor itself may become overheated and distorted by thermal expansion.

An object of the present invention comprises the provision of a rotary combustion engine in which a novel.

multi-part inner rotor is provided which is self-cooling in the sense that it is able to readily dissipate and conduct combustion heat outwardly to the outer body.

Specifically, the invention comprises the provision of a rotor having a multi-part construction consisting of an outer part facing the combustion chambers made of material of relatively high thermal conductivity, such as aluminum, and an annular inner part forming a bearing part of the rotor and made of material of relatively low thermal conductivity, such as steel. These parts are radially separated and spaced from each other except for radially overlapping elements of minimum contact area connecting the parts together for joint rotation. The outer part has a plurality of relatively broad seal strips engaging the outer body end walls. By using these features, the combustion heat is conducted to the outer body through the seal strips rather than to the core of the rotor. If desired, the end walls of the outer body may be cooled by a cooling medium circulated therein. The multi-part arrangement insulates the shaft bearing by providing a space or gap between the outer and inner parts. The sealing strip arrangement furnishes a path of conductive material from the rotor outer part to the outer body end walls.

This invention also provides radially overlapping elements connecting the inner and outer parts of the rotor for joint rotation. Said overlapping elements are composed of a plurality of circumferentially-spaced interfitted lugs and grooves bridging the gap between the inner and outer parts, said lugs and grooves having engageable side surfaces for centering the rotor inner and outer parts and for transmitting the forces between said parts. The sidesurfaces in contact between each pair of lugs and grooves is limited in area to reduce heat conduction across the gap. These overlapping lugs and grooves are arranged to allow a differential thermal expansion between the outer and inner parts.

An additional object of this invention is to provide a plurality of seal strips covering a substantial portion of each rotor end face whereby a substantial portion of each end face of the rotor is in heat conducting contact with the adjacent end wall of the outer body.

Other objects of the invention will become apparent upon reading the annexed detail description in connection with the drawing in which:

FIG. 1 is an end elevation view of a rotary combustion engine embodying this invention taken along line 1-l of FIG. 2.

FIG. 2 is a longitudinal sectional view of a rotary cornbustion engine taken along line 2-2 of FIGURE 1.

FIG. 3 is an enlarged end elevation view of an engine rotor embodying this invention taken along line 33 of FIG. 4, with the apex seals removed.

FIG. 4 is an enlarged longitudinal sectional view of an 2 engine rotor taken along line 4-4 of FIG. 3.

Referring to the drawings, a rotary combustion engine 10 is illustrated as comprising an outer body 12 having spaced end walls 14 and 16 and a peripheral Wall 18 disposed between and interconnecting said end walls to form a cavity 20 therebetween. The inner surface 24 of the peripheral Wall 18 has a multi-lobe profile which is basicallyan .epitrochoid having an axis 26 along which the end walls 14 and 16 are spaced.

A shaft 28, co-axial with the axis 26, extends through the outer body and is journaled in bearings 3d carried by the end walls 14 and 16. The shaft 28 has an eccentric portion 32 on which an inner body or rotor 34- is journaled. The inner body 34 has a plurality of apex portions 36 about its periphery, each of saidv apex portions having seal means 33 recessed in slots 39' and urged radially outward by spring means 40 into sealing engagement with the peripheral wall inner surface 24, and also side seal means 41, 42 and 43, disposed in sealing engagement with the end walls 14 and 16, to form a plurality of Working chambers 44 which vary in volume upon relative rotation between the outer and inner bodies 12 and 34. i

The outer body has intake port means 46 for supply of an intake charge to the working chambers M and has exhaust port means 48 for discharge of exhaust gases from the engine. If needed, a suitable spark plug :50 may be provided to ignite the intake charge.

In order to maintain the relative motion of the inner body 34 relative to the stationary outer body an internal gear 52 is, as illustrated, secured to the inner body coaxially with the inner body axis and is disposed in mesh annular inner part 58 of high strength material with relatively low thermal conductivity, such as steel. The inner part 58 serves as a bearing for the rotor and for this purpose a bearing bushing 76 is secured to the inner part 58. 'In order to avoid overheating or" the rotor bearing 58 and 76, the hearing has only a small area of contact with the rotor outer part 56 as hereinafter described. In addition, the rotor outer part 56 has a plurality of seal strips between each pair of adjacent apex portions, preferably three, 41, 42 and 43, mounted on each end face of said rotor outer part and covering .a substantial portion of the rotor end faces to conduct heat therefrom to the adjacent end walls 14 and 16 of the outer body. The apex seals 38 obviously are also carried by the rotor outer part 56 and the rotor internal gear 52 is suitably secured to said outer part.

Each plurality or set of seal strips 41, 42 and 43 are radially spaced and are disposed substantially parallel to the adjacent outer periphery of the rotor, and to each other.

To provide good heat conduction from the rotor outer part 56, the seal strips 41, 42 and 43 are made relatively broad to cover a substantial portion of the end faces of the rotor. In addition, the seal strips are snugly fitted in their respective recesses or grooves 78, 86 and 82. This snug fit andthe large area of the seal strips 41, 42 and 43 provides for good heat conduction from the rotor end faces into said seal strips and thence into the outer body 12.

The rotor outer and inner parts 56 and 58 are connected by at least three sets of projecting lugs 69 and facing grooves 64, as illustrated in FIG. 3, for centering and positioning the two parts 56 and 58 relative to each other. The lugs 61) project radially outwardly from the rotor inner part 58 into the grooves 64 of the rotor outer part 56 such that the fit between these lugs and grooves positions these two parts relative to each other and for transmitting the engine forces from the rotor outer part to the rotor innerpart. The lugs 60 are equally spaced and have substantially the same radial dimensions. The lugs and grooves contact each other only along their overlapping side surfaces and these surfaces are the only contacting surfaces between the outer and inner parts 56 and 58 of the rotor. Thus, the inner and outer rotor parts 56 and 58 are radially spaced, as indicated at 65 and 68. The side surfaces of both each lug 6t} and each groove 64 are circumferentially-spaced and parallel to each other and to the axis 26.

As already stated, the rotor also has a plurality of apex seals 38, one at each apex portion 36, fitted in corresponding apex slots 39 and disposed in sealing engagement with the peripheral wall inner surface 24. The apex seals 38 extend between the rotor end faces, and at each of its ends each apex seal is received in an intermediate seal member 45 which is slidably located in a recess 45a and in sealing engagement with the adjacent end wall of the outer body. Member 45 engages the adjacent end face seals 41, 42 and 43 to form a continuous seal! of the working chambers 44.

The end faces seals41, 42 and 43 are pressed into contact with the outer body end walls 14 and 16 to provide a seal therebetween and to provide for heat conduction from the rotor 34 to the outer body 12. For this purpose, the radially outermost seal strip 41 and the adjacent seal strip 42 parallel thereto are snugly fitted in their respective grooves 78 and 80 as illustrated. In addition,

4 the rotor outer part 56 has a plurality of passages each of which extends from the bottoms of the grooves '78 and '80 to the outer periphery of the rotor for communication with the adjacent working chamber 44. With this provision of the passages 7fi,'the relatively high-pressure of the medium in the working chambers during the compression and expansion stages of the working cycle urges the strips 41 and 42 against the end walls 14 and 16.

Similarly, for the radially innermost seal strips 43, which as illustrated are snugly fitted in rotor end face grooves 82, there .are a plurality of passages 72 disposed in the rotor outer part 56. Each passage 72 communicates with the bottom of the groove 82 and with the hollow interior 74 of the rotor 34, said interior being in communication with the spaces 66and 68 between the rotor parts 56 and 58.

During the induction phase in a particular working chamber 44, the pressure in that chamber is insuflicient to insure good contact of its adjacent seal strips 41 and 42 against the adjacent outer body end walls 14 and 16. At this time, the internal engine pressure within the hollow interior 74 of the rotor, which is higher than the pressure of the medium in the chamber during the induction phase, insures good contact of the associated seal strips 43 by urging them against the outer body end walls. Thus, under all operating conditions at least some of the seal strips 41, 42 and 43 are in good sealing contact with the outer body end walls.

Additionally to or in lieu of the passages 70 and 72 spring means (not shown) can be provided for urging the end face seals 41, 42 and 43 into sealing contact with the outer body end walls.

The lug and groove connections between the two parts of the rotor may be of different shape from that illustrated. Instead of a lug 'wit-h parallel side surfaces, the lug may be triangular, or pointed, or other suitable shape, and having the side surfaces of the groove correspondingly shaped. In addition, instead of a lug and groove type of connection,.it is possible to use other types of reliable connections of similar function in providing a centering action and the transfer of loading between the two parts 56 and 58.

While I have described my invention in detail in its present preferred embodiment it will be obvious to those skilled in the art after understanding my invention that various changes and modifications may be made therein without departing from the spirit or scope thereof.

What is claimed is:

l. A rotor for a rotary mechanism and having a multipart construction comprising an outer part made of material of relatively high thermal conductivity and having a plurality of circumferentiallyaspaced apex portions about its periphery and a pair of end faces, and an annular inner part made of material of relatively low thermal conductivity and being surrounded by the outer part and forming a bearing support part for the rotor, said outer and inner parts having radially overlapping elements for connecting said parts together, with said parts being otherwise radially spaced from each other, and said outer part having a plurality of seal strips mounted on each endface, there being a radially-spaced plurality of said seal strips extending from each apex portion to each adjacent apex portion at each said end face of the rotor outer part, with said seal strips covering a substantial portion of each said end face.

2. A rotor as recited in claim 1 and in which said elements comprise at least three projecting lugs on one of said rotor parts and received within facing grooves in the other of said rotor parts, said lugs and grooves having substantially parallel ciroum ferentially-spaced side surfaces with the side surfaces of said grooves contacting the side surfaces of the lugs received therein.

3. A rotor as recited in claim 2 and in which said contacting side surfaces of the lugs and grooves are the only contacting surfaces between said outer and inner parts.

4. A rotor as recited in claim 1 and in which each said apex portion has a sealing member, said sealing member extending between said rotor end faces and being in sealing engagement at each end with said end-face seal strips.

5. A rotor as recited in claim 1 and in which the seal strips between each adjacent pair of apex portions are disposed parallel to the adjacent outer periphery of said rotor and are substantially parallel to each other.

6. A rotor as recited in claim 5 and in which each radially-outermost seal strip and each adjacent seal strip parallel thereto are snugly fitted in a groove in its rotor end face and in which the rotor outer part has a plurality of pass-age providing communication between the bottoms of said grooves and the adjacent working chambers.

7. A rotor as recited in claim 5 and in which each radially-innermost strip is snugly fitted in an end-face groove and in which the rotor has a hollow space between the rotor parts and the rotor outer part has a plurality of passage providing communication between the bottoms of said grooves and said rotor hollow space.

8. A rotor for use in a rotary combustion engine having an outer body comprising a pair of spaced end walls and an interconnecting peripheral wall to form a cavity therebetween within which said rotor is rotatably received for cooperation with the inner surface of the cavity to form a plurality of working chambers between the rotor and outer body which vary in volume upon rotation of the rotor relative to the outer body; said rotor having a multi-part construction comprising an outer part made of material of relatively high thermal conductivity and having a plurality of circumferentially-spaced apex portions about its periphery and a pair of end faces and an annular inner part made of material of relatively low thermal conductivity and being surrounded by the outer part and forming a bearing part for the rotor, said outer and inner parts having radially overlapping elements for connecting said parts together, with said parts being otherwise radially spaced from each other, and said outer part having a plurality of end-wall-engaging seal strips mounted on each end face, there being a radially-spaced plurality of such seal strips extending from each apex portion to each adjacent apex portion at each said end face of the rotor outer part, with said seal strips covering a substantial portion of each said end face.

No references cited.

Claims (1)

1. A ROTOR FOR A ROTARY MECHANISM AND HAVING A MULTIPART CONSTRUCTION COMPRISING AN OUTER PART MADE OF MATERIAL OF RELATIVELY HIGH THERMAL CONDUCTIVITY AND HAVING A PLURALITY OF CIRCUMFERENTIALLY-SPACED APEX PORTIONS ABOUT ITS PERIPHERY AND A PAIR OF END FACES, AND AN ANNULAR INNER PART MADE OF MATERIAL OF RELATIVELY LOW THERMAL CONDUCTIVITY AND BEING SURROUNDED BY THE OUTER PART AND FORMING A BEARING SUPPORT PART FOR THE ROTOR, SAID OUTER AND INNER PARTS HAVING RADIALLY OVERLAPPING ELEMENTS FOR CONNECTING SAID PARTS TOGETHER, WITH SAID PARTS BEING OTHERWISE RADIALLY SPACED FROM EACH OTHER, AND SAID OUTER PART HAVING A PLURALITY OF SEAL STRIPS MOUNTED ON EACH END FACE, THERE BEING A RADIALLY-SPACED PLURALITY OF SAID SEAL STRIPS EXTENDING FROM EACH APEX PORTION TO EACH ADJACENT APEX PORTION AT EACH SAID END FACE OF THE

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