United States Patent (19) 11) 4,270,495 Freudenstein et al. 45) Jun. 2, 1981 (54) VARIABLE DISPLACEMENT PSTON (56) References Cited ENGINE U.S. PATENT DOCUMENTS 1,673,280 6/1928 Evans ............................... 123/197 R (75) Inventors: Ferdinand Freudenstein, Riverdale, 2,653,484 9/1953 Zecher .... 123/197 R N.Y.; E. Roland Maki, Rochester, 4,112,826 9/1978 Cataldo .............................. 123/48 B Mich. FOREIGN PATENT DOCUMENTS 1015857 10/1952 France ................................... 123/54 R 73) Assignee: General Motors Corporation, Detroit, Primary Examiner-Craig R. Feinberg Mich. Attorney, Agent, or Firm-Robert J. Outland 57 ABSTRACT 21 Appl. No.: 44,265 A family of balanceable, variable displacement recipro cating piston engine arrangements is disclosed. The Filed: May 31, 1979 arrangements include multiple parallel cylinders having 22 pistons movable therein in balanceable fashion through a fixed geometry rocker mechanism driving oscillating (51) Int. Cl......................... F02B 75/26; FO1B 31/14 links which are adjustable to provide control of the (52) U.S. C. ................................ 123/54 B; 123/78 E; piston displacement and compression ratio. Both in-line 123/197 AC and side-by-side cylinder arrangements are possible. 58 Field of Search ................. 123/54 R, 54 B, 48 R, Even firing intervals are preferably provided. 123/48 B, 53 R, 53A, 78 R, 78 E, 78 F, 78 BA, 197 4 Claims, 4 Drawing Figures VP se-27 As Eif 2é- NN e-NNNNNEN 2S INNaz a- N NN ANNN (O) SR a- NN NN,NN NYN NN-ANN NN a NN N R S. N 2 P N U.S. Patent Jun. 2, 1981 Sheet 1 of 2 4,270,495 SQ ^ZOZ,Z,Z(ZZT,UZZ-Z-Z S(S(SCNCS)((SCS)(S)(S)(S)(S)(S)(S)(S)(V) QSOESOESOESOESOEK(SOESOESOESOESOESOESOESOESOESOES)(S)(S. Œ|||NS ZzzzzzzzzzzzzZzZzZzzzzz ZZZZZZZ ZZZZZZZ U.S. Patent Jun. 2, 1981 Sheet 2 of 2 4,270,495 4,270,495 1. 2 engine having a cylinder block 11 defining a pair of VARIABLE DISPLACEMENT PISTON ENGINE parallel cylinders 12, 14 arranged in side-by-side fash ion. The cylinders are closed at one end by a cylinder TECHNICAL FIELD head 15 which may be provided with the usual inlet and This invention relates to variable displacement en 5 exhaust ports, valves, actuating gear and ignition means, gines and, more particularly, to balanceable engine none of which are shown. arrangement having efficient power-transmitting and Between the cylinders there is disposed for reciproca stroke-varying mechanism whereby the displacement of tion parallel with the cylinder axes a stroke control the pistons is varied by varying the piston stroke. actuator. 16. At its bottom end, the actuator 16 oscillat 10 ingly supports by means of a pin 18 an oscillating link BACKGROUND OF THE INVENTION 19. This link includes oppositely extending arms 20, 22, Many types of variable stroke mechanisms have been the outer ends of which are operatively connected by proposed for use in engines to vary the displacement of connecting rods 23, 24 with pistons 26, 27 reciprocably the pistons. Recently it has again been suggested that disposed within the cylinders 12, 14, respectively, and variable displacement engines could have advantages 15 forming therewith variable volume working and com over fixed displacement engines in the areas of both bustion chambers 28. emission control and overall efficiency. However, to The oscillating link 19 is pivotally connected with a obtain these advantages it is necessary that the mechani pair of bearing-like control blocks 30, 31 by axially cal linkage used to transmit power from the engine, aligned bearing journals 32 disposed on an axis parallel pistons to the output shaft itself be arranged to transmit 20 with and spaced below the axis of the stroke control the power in an efficient manner. It is further desirable actuator pin 18. The control blocks 30, 31 are slidably that the mechanism be balanceable within limits consid carried within opposed bearing surfaces 34 formed ered acceptable for application in automotive vehicles. within a rocker 35 that is pivotally supported within the U.S. Pat. No. 4,112,826 Cataldo assigned to the assignee engine block 11 on support pins 36, 38 for oscillation on of the present invention discloses some examples of 25 a separate longitudinal axis. The rocker is connected engine arrangements proposed to provide some or all of through a coupler pin 39 with a coupler rod 40, that, in these features. turn, connects with the eccentric crankpin 42 of a SUMMARY OF THE INVENTION crankshaft 43 rotatable on a longitudinal axis normal to The present invention provides novel but practical 30 the plane of the cylinders and parallel with the axes of arrangements for piston engines having variable stroke oscillation of the rocker 35 and the oscillating link 19. and displacement mechanism capable of providing effi OPERATION cient operation with force and rolling moment balance and, in most cases, even firing when used in either two The operation of the embodiment of FIGS. 1 and 2 is stroke or four stroke cycle internal combustion modes 35 as follows. of operation. The various possible arrangements all Rotation of the crankshaft 43 moves the eccentric contemplate the provision of parallel pairs of cylinders crankpin 42 in an orbit which drives the coupler 40, having pistons with balanced motions arranged in multi causing the rocker 35 to oscillate through a predeter ples of two to four cylinders and in either in-line or mined constant angle around the pivot axis of its sup side-by-side arrangements. port pins 36, 38. The motion of the rocker is transmitted These and other features and advantages of the inven through the control blocks 30, 31 to the bearing journals tion will be more fully understood from the following 32 of the oscillating link causing this link to oscillate description of certain preferred embodiments taken about the axis of the actuator pin 18. This oscillation, together with the accompanying drawings. acting through the extending arms 20, 22 and connect 45 ing rods 23, 24 is converted to reciprocating motion of BRIEF DESCRIPTION OF THE DRAWINGS the pistons 26, 27 in the respective cylinders, the piston In the drawings: movements being in opposite directions so as to provide FIG. 1 is a transverse cross-sectional view through balance of the reciprocating components. one pair of cylinders of an internal combustion engine To adjust the stroke of the pistons and, therefore, having a variable stroke variable displacement power 50 their displacement, the stroke control actuator 16 may transmitting mechanism formed according to the inven be raised upwardly from the maximum stroke position tion; shown in the drawings to some reduced stroke position FIG. 2 is an enlarged cross-sectional view taken gen within the range of stroke control. This upward move erally in the plane of the line 2-2 of FIG. 1 and illus ment raises the pin 18 upwardly along the central axis or trating the construction of certain portions of the vari 55 plane extending between the cylinders which in turn able stroke mechanism; lifts the oscillating link and the pistons which are at FIG. 3 is a partially diagrammatic pictorial view tached thereto. At the same time, however, the lower illustrating the arrangement of the longitudinally dis portion of the oscillating link moves within a path de placed mechanisms of a side-by-side four-cylinder en fined by the sliding of the control blocks 30, 31 within gine arrangement according to the invention; and 60 the bearing surfaces 34 so that in the position shown in FIG. 4 is an isolated view of the engine actuating the drawings, the angular tilt of the oscillating link is mechanism indicating relationships between the various reduced. When the proper geometric relationships have elements. been selected, this change is sufficient to offset the rais ing of the piston-oscillating link assembly so that the top BEST MODE FOR CARRYING OUT THE 65 dead center position of the pistons is properly adjusted INVENTION to maintain a predetermined (probably nearly constant) Referring now to FIGS. 1 and 2 of the drawings, compression ratio while the length of stroke of the numeral 10 generally indicates an internal combustion individual pistons is reduced. In this way, variation of 4,270,495 3. 4. engine displacement with a limited prescribed change in h = distance from the oscillating link pivot axis E to compression ratio is provided for. the axis Q of the control blocks. PRIMARY ENGINE BALANCE l=length of piston connecting rods from points F to G and H to . To obtain essentially complete primary balance of the 5 CR = compression ratio defined by the expression major engine components without adding external bal CR = (S--Ch)/Ch where S=piston stroke and ancing devices, it is necessary not only to provide oppo Ch=clearance from piston to cylinder head at top sitely moving pairs of pistons but also to provide at least dead-center of a stroke. one additional stroke-varying drive mechanism similar R= radius of the oscillating link from point E to point to the one previously described. Such an arrangement is 10 H or F. shown in FIG. 3 of the drawings, wherein two pairs of S=stroke; the linear motion of a piston between its mechanisms are shown connected to a crankshaft 43a end points of travel at a given stroke control actua with oppositely eccentric crankpins 42a, 42b. Since the tor position. components of each of the mechanisms shown in FIG. 3 are similar to those of the arrangement of FIG. 1, like 15 Po=distance from the mechanism central axis M to numerals have been used to identify the similar compo the left and right cylinder centerlines as repre nents, with the forward mechanism components being sented by the piston pin axes G, I.