Patent Publication Number: US-3877849-A

Title: Construction of rotor for rotary mechanisms

Description:
United States Patent 1 1 1111 3,877,849  
 Wieland 1 1 Apr. 15, 1975 [54] CONSTRUCTION OF ROTOR FOR ROTARY 1,701,392 2/1929 Short 29/1565 R MECHANISMS 1,854,455 4/1932 Day 29/1565 R 2,341,836 2/1944 Wood 29/1565 R Inventor: Werner wielanmoberelseshelm, 3,059,585 10/1962 Froede et a1 418/91 Germany 3,259,114 7/1966 Gassmann 418/61 A ,299, 62 11967 P 41891 [731 Assignees: i NSU A1110 3,302,224 211967 1213310161 418/91 s i fi g fi j 3,333,763 8/1967 Jungbluth et 31.... 418/61 A an e -m- In 3,721,510 3/1973 Gilbert 418/13 Bodensee, both of Germany 3,740,175 6/1973 Kell 418/113 [22] Filed: Dec. 10, 1973 [21] APPL NO: 423,159 Primary Examiner-John J. Vrablik Attorney, Agent, or FirmArthur Frederick [30] Foreign Application Priority Data Dec. 21, 1972 Germany 2262619 [57] ABSTRACT 52 us. (:1 418/61 A; 418/91; 29/1565 R The rotor comprises a plurality of rotor components [51] &#39;3 CI Folc 1/025 F04C 17/02; B2319 15/10 produced by stamping and cutting sheet metal mate- [58] new of Search 418/6] 91; 29/1565 R; rial and bonding the rotor components together into a 123/801 unitary assembly. The regions of the assembly requir- [56] R f Ct d ing surface hardening and machining are so treated.  
 e erences 1 e UNITED STATES PATENTS 1,282,936 10/1918 Pribil 29/1565 R 13 Claims, 5 Drawing Figures CONSTRUCTION OF ROTOR FOR ROTARY MECHANISMS The invention relates to rotors for rotary mechanisms of the Wankel el al. type disclosed in US. Pat. No. 2,988,065, and more particularly to a lightweight rotor and the method of construction thereof.  
 BACKGROUND Heretofore, rotors for rotary mechanisms of the Wankel type have been constructed of cast iron or aluminum and machine treated and worked to the desired finish and dimensions. The fabrication of these rotors require expensive molds and sand cores. The removal of all residual sand from the hollow recesses of the castings is difficult and time-consuming. In addition, the wall thicknesses of the cast rotor are relatively great, necessitating relatively large bearing and shaft components and an engine of relatively large weight to horsepower ratio. Further disadvantage of presently constructed rotors is that the walls of the cast rotor are not uniform and therefore require accurate machining to provide the finished rotor with the required dynamic balance. The rotors which are produced by assembling machined and/or cast components, such as exemplified in the U.S. Pat. No. 3,059,585, suffer from some of the aforesaid disadvantages of the conventional integral, cast rotor.  
  It is therefore an object of this invention to provide a rotor for rotary mechanisms of the Wankel type, which rotor is of relatively simple lightweight construction and wherein machine working and treatment is minimal.  
  Another object of the present invention is to provide a rotor for a rotary mechanism of the Wankel type, which rotor is capable of being more effectively cooled than heretofore known rotors.  
  A further object of this invention is to provide a rotor for a rotary mechanism of the Wankel type, the fabrication of which does not require use of casting molds or discs nor requires machine finishing of the outer surface, particularly the peripheral flank portions of the rotor.  
  A still further object of the present invention is to provide a method of fabricating a rotor for a rotary mechanism of the Wankel type which method includes the steps of securing together a plurality of rotor components each of which is produced by stamping and cutting metal sheet material.  
 A feature of this invention is the fabrication of component parts of the rotor to desired size from flat sheet metal, such as steel, by a forming and cutting process, such as punch press operation, and then positioning and soldering or welding the components together into a lightweight assembly, having component wall thicknesses of uniform dimensions and requiring no machine surface finishing or machining for dynamic balance.  
 SUMMARY Accordingly, the present invention contemplates a novel rotor for a Wankel type rotary mechanism and method of fabrication thereof which rotor comprises a plurality of rotor components secured together into an integral rotor assembly. More specifically, the rotor comprises a two-piece hub secured together and connected on opposite sides to two side wall members or elements, the side wall elements being secured at their periphery to flank portions. The side wall elements are each provided with a hole coaxial with the bearing bore of the hub and of a slightly larger diameter than the hub bore. A tubular member extends axially and is connected at opposite ends to the side wall elements at each of the apex portions of the latter members to provide, during operation, equalization of the pressure adjacent each of the side wall elements. The flank portions may be reinforced by brackets which are each disposed between and secured to side wall elements, the hub and a flank portion. A solid bar is disposed at the adjacent ends of next adjacent flank portions and between opposite side wall elements. The solid bars are secured at their opposite end portions to the end wall elements and to theend portions of the adjacent flank portions. Each of the solid bars are provided with an axially extending groove and opening for accommodating an apex seal blade and pin assembly such as the type disclosed in US. Pat. Nos. 3,400,691, 3,300,124 and 3,180,562. One of the side wall elements is provided with integrally formed internal gear teeth at the periphery of the hole therein. Each of the components comprising the rotor assembly is fabricated by stamping and cutting a flan, planchet or blank of sheet metal material, such as steel, which components are then secured together at their points of abutment by soldering, brazing, or suitable bonding method, such as welding or epoxy adhesive gluing, to produce a unitary rotor assembly.  
  In accordance with the fabrication method of this invention the components are formed and cut to the desired predetermined shape and dimensions. The solid bars are cut to the desired lengths from bar stock having the desired peripheral shape. The internal gear teeth in one of the side wall members is produced by accurate forming and cutting. It is preferred that all of the components be first spot welded to one of the side walls so that gaps are left for solder. Thereafter, a pastelike soldering material is applied to the gaps and the components at the point of abutment of the components to the other side wall element. The other side wall element is then positioned in abutment on the other components and the assembly is placed in a furnace to be heated and effect a soldering of the components into a unitary assembly. Thereafter, the side wall element having the gear teeth-is subjected to hardening only in the region of the gear teeth in any suitable manner, such as by high frequency, induction heating and quenching. This is then followed by the step of machine finishing the bearing hole of the hub, the internal gear teeth and forming the grooves and holes for receiving the apex seal assemblies and side gas and oil seals.  
  In an alternative embodiment of the method of fabrication of the rotor according to this invention, the components may be secured together by suitable welding techniques, such as electron-beam or laser-beam welding techniques and apparatuses.  
 BRIEF DESCRIPTION OF THE DRAWINGS The invention will .be more fully understood from the following detailed description thereof when considered in connection with the accompanying drawing wherein one embodiment of the invention is illustrated by way of example and in which:  
  FIG. 1 is a side elevational view of a rotor according to this invention with parts thereof broken away for illustration purposes;  
  FIG. 2 is an end elevational view of the rotor shown in FIG. 1;  
  FIG. 3 is a view in cross-section taken along line 33 of FIG. 1;  
  FIG. 4 is an exploded view of the components of the rotor shown in FIGS. 1 to 3; and  
  FIG. 5 is a perspective view of two of the reinforcingbaffle plates forming part of the rotor assembly of this invention.  
 DESCRIPTION OF THE PREFERRED EMBODIMENT Now referring to the drawings and more specifically FIGS. 1 to 4, the reference number generally designates a rotor according to this invention which rotor has application to rotary mechanisms of the type disclosed in the US. Pat. No. to Wankel et al, 2,988,065. While the rotor 10 is shown as the type having three flank portions, the invention is not limited thereto. It is therefore to be understood that the invention has application to rotors having two or more than three flank portions without departure from the scope and spirit of the invention.  
  The rotor 10, as best illustrated in FIG. 4, comprises a plurality of components which are produced by stamping and cutting of flans, planchets or blanks of metal material, such as sheet-steel and then secured together by suitable soldering, brazing, welding, epoxy gluing, or other bonding process- One of the rotor components is a bearing hub 12 consisting of two identically shaped ring-shaped elements 14 and 16. Each ring-shaped element has a tubular body portion 18 and an integral, annular, radially extending flange portion 20. The ring-shaped elements 14 and 16 are secured together in coaxial, mirror relationship at their tubular body portions 18 so as to define a bearing hole 22.  
  Another rotor component is a side wall element 24 which has a body of generally triangular shape with three intersecting arcuate-shaped edge surfaces 26 which define apex portions 28. The side wall element 24 has an outer surface 30 and an inner surface 32 and a cross-sectional dimension greater than bearing hub 12 (see FIG. 2). A centrally located opening 34 is provided in the side wall element to extend through outer surface 30 and inner surface 32. The opening 34 is of a diameter slightly greater than the diameter of bearing hole 22 of bearing hub 12.  
  A second side wall element 36 constitutes another rotor component and is of the same triangular shape and size as side wall element 24. The side wall element 36 has a cross-sectional dimension substantially the same as side wall element 24 and have an outer surface 38 and an inner surface 40. The side wall element 36 is made from hardenable steel material and is provided witha centrally located internal gear toothed portion 42 which is of substantially the same diametral size as opening 34 in side wall element 24. Similar to side wall element 24, side wall element 36 has three intersecting edge surfaces 44 which define apex portions 46.  
  Further components of rotor 10 are the three arcu ate-shaped flank elements 48 each of which has a depression 50 in the outer surface thereof and a curvature complementary to the curvature of edge portions 26 and 44 of side wall elements 24 and 36, respectively. The length of each flank element 48 is such that when assembled, the adjacent opposite ends thereof are in close spaced relation (see FIG. 1). The width of each flank element 48 is of such size that in the assembled condition, the flank element overlaps edge surfaces 26 and 44 (see FIG. 2).  
 As best shown in FIGS. 1, 2 and 3, rotor 10 also includes three pairs of brackets 52 which are disposed I adjacent each of the flank elements 48and between bearing hub 16, side wall elements 24 and 36 and flank elements 48. As best illustrated in FIG. 5, each bracket 52 comprises two integral web portions 54 and 56 which lie in planes substantially normal to each other.  
 The web portion 54 has an edge surface 58 which has a configuration complementary to the shape of the inner surface of the adjacent flank element 48 including part of depression 50, while web portion 56 has an edge surface 60 which is coextensive with edge surface 58 and has a configuration complementary to the shape of the inner surface of the adjacent flank element in another plane, including part of depression 50. The web portion 54 also has an edge surface 62 curved to complement the curvature of the outer peripheral surface of tubular body portion 18 of bearing hub 12. The web portion 56 has an edge surface 64 that. in the assembly,  
 extends axially in abutment against the outer peripheral surface of body portion 18. The web portion 56 also i&#39; has an end edge surface 66 formed and dimensioned to abut the surfaces 32 and 40 of side wall elements 24 and 36, respectively and the flanges 20 of bearing hub 12 (see FIG. 2).  
 The brackets 52 serve to structurally reinforce flank elements 48 and as baffles for directing cooling fluid intothe spaces within the assembled rotonTo provide for directing the flow of lubricating oil employed as a coolant fluid, such as exemplified in the US. patents to Bentele et al., No. 3,176,915, and Sollinger, No. 3,176,916, each pair of brackets 52 (see FIG. 5) is disposed between the adjacent flank element 48, side wall elements 24 and 36 and bearing hub 14 so that web portions 56 of each pair of brackets bisects one of three elongated inlet ports 68. The inlet ports 68 are ar-r ranged in circumferential spaced relationship to each other in one side of bearing hub 12. A plurality of elongated outlet ports 69 are arranged in circumferential spaced relationship to each other in the opposite side of bearing hub 12 from inlet ports 68. In operation of rotor 10 the flow of cooling oil in ports 68 adjacent brackets 52 is split as shown by the arrows in FIGS. 1,  
 2 and 3 by web portions 56 and each stream is guided by web portions 54 radially outwardly toward the inner 1 surface of flank elements and the juncture of the flank.  
 elements and the side wall elements 24 and 36 to which the flank elements are connected. The cooling oil also flows axially around the radially extending edges 55 of brackets 52 and thence out of outlet ports 69.  
 Improved cooling effectiveness is achieved according to this invention at the juncture of flank elements 48 and side wall elements 24 and 36, by providing between inner surface 32 and edge surface 26 of side wall element 24 a chamfered or beveled surface 70 and a similar beveled surface 72 between inner surface 40 and edge surface 44 of side wall element 36. The chamfered or beveled surfaces 70 and 72 expose more of the. inner surface of flank elements 48 to, the flow of cooling fluid so that the flank elements are better cooled, particularly the flank elements of an internal combustion engine rotary mechanism, in which the flank elements are subjected to very high combustion gas temperatures.  
  While the present invention discloses brackets of the unique configuration shown in FIG. 5, the invention is not to be limited thereto. The brackets can have any suitable shape to interconnect the flank elements and hub without departing from the scope and spirit of this invention.  
  Another component of rotor 12 is three solid metal bar inserts 74. Each metal insert is dimensioned in length to extend between the aligned apex portions 28 and 46 of end wall elements 24 and 36 and is receivable at its opposite ends in a notch 76 provided in the apex portions 28 and 46 of end wall elements 24 and 36. The peripheral surface of the inserts is polygonal in shape with two adjacent surfaces being formed complementary to the inner surfaces of flank elements 48 so as to lie substantially flush against the flank elements. The metal inserts 74 serve to provide forthe machining of the grooves and bores for receiving apex seal assembly components, such as shown in Bentele US. Pat. Nos. 3,033,180 and 3,180,562.  
  To insure during the operation of rotor 12 that the fluid pressure acting against side wall elements 24 and 36 is substantially equal, an open ended tubular member 77 is secured at opposite ends in registered holes 78 in each of the apex portions 28 and 46 of side wall elements 24 and 36, respectively. The holes 78 are located radially inwardly of the side gas seals (not shown).  
  The method according to this invention of bonding the individual components of rotor into a unitary structure is preferably accomplished by soldering. it is preferred that all of the components of the rotor, except with respect to one of the side wall elements 24 or 36, are first spot soldered to the other side wall element. For purposes of this description it will be assumed that the parts are first attached to side wall element 24. The interrupted points of soldering may be in close spaced relationship, as for example 0.2 mm or 0.3 mm apart. A soldering paste of suitable composition, such as copper with an additive of nickel, is applied where the parts contact between the soldered points and on the surfaces of contact between the rotor components and the side wall element 36. The side wall element 36 is then placed in contact against the subassembly and the entire assembly is placed in a furnace at a suitable temperature to effect melting of the solder. 1n the case of a soldering paste of copper-nickel, a temperature of about 1100C (2282F) is preferred. After the rotor components are soldered together, side wall element 36, in the region of the internal gear tooth portion 42, is surface hardened in any suitable manner, such as high frequency induction heating and quenching. Similarly, the surfaces 18 of bearing hub 12 defining the bearing hole 22 are also hardened. Thereafter, the toothing of internal gear tooth portion 42 and the apex and side seal recesses and grooves (not shown) are machined in any suitable manner well known to those skilled in machining practices.  
  In the alternative embodiment of the fabrication method, the rotor components may be secured together by welding instead of soldering. Particularly suitable welding techniques are electron-beam and laser-beam welding.  
  It is believed now readily apparent that the present invention provides a relatively lightweight balanced rotor. The invention also provides a method of fabricating such rotor in which machining is minimal. The method provides the ability to accurately control rotor component wall thickness and shape so that dynamic imbalance is negligible.  
  Although several alternatives are revealed herein, it is to be expressly understood that the invention is not limited thereto. Various changes can be made in the arrangement of parts and method steps without departing from the spirit and scope of the invention as the same will now be understood by those skilled in the art.  
 What is claimed is: i  
  1. A rotor having a plurality of contiguous flank portions disposed for eccentric rotation within and relative to a housing cavity partially defined by a trochoidal peripheral surface, the rotor comprising:  
 a. a bearing hub having opposite end portions lying in planes normal to the axis of the bearing hub;  
 b. two substantially congruent side wall elements disposed on opposite sides of said bearing hub and lying in substantially parallel planes;  
 c. a plurality of flank elements interconnecting the peripheral edge portions of said two side wall elements and arranged in endwise alignment;  
 d. said bearing hub being dimensioned to extend between and engage said side wall elements at the end portions;  
 e. each of the side wall elements having a plurality of inner peripheral edge surfaces each of which surfaces is provided with a chamfer adjacent an abutting flank element; and  
 f. said bearing hub, side wall elements and flank elements each being constructed of cut and formed sheet metal material and secured together into a unitary structure.  
  2. A rotor having a plurality of contiguous flank portions disposed for eccentric rotation within and relative to a housing cavity partially defined by a trochoidal peripheral surface, the rotor comprising:  
 a. a bearing hub having opposite end portions lying in planes normal to the axis of the bearing hub;  
 b. two substantially congruent side wall elements disposed on opposite sides of said bearing hub and lying in substantially parallel planes;  
 c. a plurality of flank elements interconnecting the peripheral edge portions of said two side wall elements and arranged in endwise alignment;  
 d. said bearing hub being dimensioned to extend between and engage said side wall elements at the end portions;  
 c. said bearing hub having an open ended tubular portion and radially extending, annular flange portions integral with and at the opposite ends of the tubular portion;  
 f. the bearing hub having a plurality of circumferentially spaced openings therein which serve in the use of the assembled rotor to pass cooling fluid into the space between the annular flange portions;  
 g. a plate disposed between the side wall elements,  
 the tubular and annular flange portions of the bearing hub and adjacent each of said openings for dividing the cooling fluid stream in two streams and deflecting each of the two streams in opposite directions circumferentially of and radially outward from the bearing hub; and  
 h. said bearing hub, side wall elements, flank elements and the plate being constructed of cut and formed sheet metal material and secured together into a unitary structure.  
  3. A rotor having a plurality of contiguous flank portions disposed for eccentric rotation within and relative to a housing cavity partially defined by a trochoidal peripheral surface, the rotor comprising:  
 a. a bearing hub having opposite end portions lying in planes normal to the axis of the bearing hub;  
 b. two substantially congruent side wall elements disposed on&#39;opposite sides of said bearing hub and lying in substantially parallel planes;  
 c. a plurality of flank elements interconnecting the peripheral edge portions of said two side wall elements and arranged in endwise alignment;  
 d. said bearing hub being dimensioned to extend between and engage said side wall elements at the end portions;  
 e. each side wall element has a plurality of peripheral edge surfaces which converge to define a plurality of apex portions;  
 f. a solid bar for each pair of apex portions disposed to extend between the apex portion of one side wall element to the corresponding apex portion of the other side wall element to thereby interconnect the side wall elements and to provide material in which recesses can be provided for receiving apex seal devices; and said bearing hub, side wall elements and flank elements each being constructed of cut and formed sheet metal material and secured together and to said solid bars into a unitary structure.  
  4. The apparatus of claim 3 in which&#39;an opening is provided in each apex portion of each of said side wall elements to receive the solid bars therein.  
  5. The method of fabricating a rotor having two spaced side wall elements interconnected at their periphery by a plurality of contiguous converging flank portions, the rotor being for use in a rotary mechanism of the type having a rotor cavity partially defined by a trochoidal peripheralsurface, the method comprising the steps of:  
 a. forming by stamping and cutting a bearing hub from relatively thin sheet metal material;  
 b. forming by stamping and cutting two substantially congruent side wall elements having a plurality of converging edge surfaces from relatively thin sheet metal material;  
 c. forming by stamping and cutting a plurality of flank elements corresponding in number to the number of edge surfaces of each of the side wall elements; (1. cutting solid metal inserts from bar stock to the length required for each insert to extend between the side wall elements at each of the points of con-.  
 vergence of the flank elements; and  
 e. assembling and bonding the bearing hub, inserts, flank elements and said side wall elements into a unitary structure. i  
  6. The method of claim 5 wherein bonding is accomplished by soldering.  
  7. The method of claim 5 wherein bonding is accomplished by welding.  
  8. The method of claim 5 wherein bonding comprises applying a paste-like soldering mediumto the areas of contact between the bearing hub, side wall elements, inserts and flank elements and exposing the entire as sembly to sufficiently high temperatures to melt the soldering medium.  
  9. The method of claim 8 wherein the soldering medium is a copper solder with anickel additive and the assembly is exposed to a temperature of about 1100C.  
  10. The method of claim 5 wherein assembling and bonding comprises the step of:  
 a. assembling the bearing hub, inserts, flank elements in proper relationship to each other and one of the side wall elements, and soldering these components together at spaced points in the region of contact;  
 b. applying solder to the spaces between the points of solder, and on the regions of contact with the other side wall elements;  
 0. positioning said other side wall element into the assembly; and,  
 d. heating the entire assembly to melt the solder to render the assembly a single unitary structure.  
  11. The method of claim 10 wherein the points of solder are spaced apart between about 0.2 mm and about 0.3 mm.  
 12. The method of claim 5 wherein one of said side wall elements is formed to have internal gear teeth and, I after assembly and bonding, the region of the internal gear teeth is hardened.  
  13. The method of claim 12 wherein hardening is by the process of high frequency induction heating and quenching.