US2473759A

US2473759A - Two-cycle opposed piston engine

Info

Publication number: US2473759A
Application number: US687916A
Authority: US
Inventors: Mallory Marion
Original assignee: Mallory Research Co
Current assignee: Mallory Research Co
Priority date: 1946-08-02
Filing date: 1946-08-02
Publication date: 1949-06-21
Anticipated expiration: 1966-06-21

Description

' June 21, 194-9. M. MALLORY 2,473,759

TWO-CYCLE OPPOSED PISTON ENGINE Filed Aug. '2, 194 2 sheets-sheet 1 IT'S-l- INVEN TOR. MARION MALL an June 21, 1949. M. MALLORY TWO-CYCLE OPPOSED PISTON ENGINE 2 Sheets-Sheet 2 Filed Aug. 2, 1946 INVEN TOR.

MAHIUN MALLDHY Patented June 21, 1949 TWO-CYCLE OPPOSED PISTON ENGINE Marion Mallory, Detroit, Micln, assignor to The Mallory Research Company, Detroit, Mich a corporation of Michigan Application August 2, 1946, Serial No. 687,916

8 Claims. (Cl. 12351) 1 This invention relates to internal combustion engines. and particularly to improvements on the general type of engine disclosed in my Patent No. 2,345,056, datedMarch 28, 1944.

In such an engine, the compression, combus tion and exhaust of the charges take place between two pistons operating in a common cylinder and having their separate crankshafts geared together with a ratio of two-to-one, with the slower moving piston controlling an exhaust port. Heretofore, so far as I am aware, the outward movement of the slowpiston has been utilized as the main power generating stroke of the engine due to its crank having a lead of approximately 45 over that of the fast piston, and also to the positioning of the exhaust port'so that it will be uncovered by the slow moving piston on an outstroke thereof during approximately the last 45 movement of its crank. This action has not only resulted in a short power stroke but has impeded the exhaust due to late opening of the exhaust and its necessarily restricted area.

The primary object of the present invention is to obtain a long firing stroke before opening of the exhaust port whereby to increase the power efficiency of the engine. This advantage is accomplished by utilizing the fast moving piston as the-main power piston and the slow moving piston as the one controlling the exhaust, whereby the fast piston has a power stroke of approximately a full 180 movement of its crank, the slow piston has a coincident power stroke of approximately one-half of its outstroke from inner dead center position, and the exhaust port is relatively large and is uncovered by the slow moving piston for approximately a 180 movement of its crank from a point substantially 90 past inner dead center. To efiect this, the crank of the fast piston is given a lead of approximately 45 over that of the slow piston crank, so that when the former is at inner dead center the latter is approximately 45 beyond such position, the 'ex-' haust port is positioned to start opening when the slow piston is at approximately half position in its outstroke and the area of such port is enlarged.

Other objects and advantages of the invention will be apparent from the following detailed de- 2 (Y with parts omitted, showing the position of the movable parts at approximately the end of the power stroke of the fast moving piston, or at approximately the beginning of the opening of the exhaust by the slow moving piston, with the fuel valve still closed and the air admission valve starting to open; Fig. 3 is a view similar to Fig. 2, showing the position of the parts at the end of the outstroke of the slow moving piston, with the fuel valve starting to open and the air admission valve just closed; Fig. 4 is a similar view showing the relative position ofthe parts when the slow moving piston has just moved to exhaust port closing position on its compression stroke, with both the fuel and the air admission valves closed, and Fig. 5 is a reduced fragmentary cross-section on the line 5-5 in Fig. 2.

In the drawings, I designates an engine cylinder the ends of which open intorespective crank cases 2 and 3. Pistons 4 and 5 operate in opposite ends of the cylinder and are connected to the crank arms of respective crankshafts 6 and I,

the former in the case 2 and the later in the case 3. The crankshafts are connected in any suitable manner, as by a gear train 8, to have a turning ratio of two-to-one, so that the shaft 6 makes two complete revolutions to one of the shaft 1.

scription, and from the accompanying drawings,

' the power stroke, with both the air and fuel admission valves closed; Fig. 2 is a similar section The relationship of the connection of the pistons with their shafts is preferably such that when the wrist-pin of shaft I is in its inner dead center position, the wrist-pin connection of shaft 6 is approximately 45 advanced over its inner dead center position, as shown in Fig. 1. The rotation of the two shafts is preferably but not necessarily in counter-clockwise direction.

The cylinder has an exhaust port I0 that is initially uncovered by the piston 5 when the piston has approximately moved one-half of its outstroke with its crank moved approximately from inner dead center, as indicated in Fig. 2. The exhaust port I0 is of such cross-area that it will not be completely uncovered until the piston 5 has approximately reached the limit of its outstroke, thus causing the port to be open for approximately a movement of the associated crank or until on its instroke it has reached the position shown in Fig. 4. This greatly facilitates exhaust of all of the burnt gases from the cylinder after each explosion.

The air and fuel charges are admitted to the cylinder vI through a. centrally located port II from a chamber [2 to which said charges are respectively admitted through ports l3 and I4 controlled by respective "valves 15 and It. The control of the air valve I5 is such that an air charge is admitted to the cylinder starting at approximately the time of first uncovering of the exhaust port It by the piston 8 and continuing until the piston has completed its outstroke, or during the 90 movement of the associated crank from the position shown in Fig. 2 to that in Fig. 8. The fuel valve is timed to start its opening when the slow moving crank is at approximately its outer dead center position indicated in Fig. 3. and is closed by approximately the end of a 90 inward stroke from such position or approximately coincident with the closing of the exhaust port. This causes a complete scavenging of th burnt gases from the cylinder after each explosion and before the admission of a fresh fuel charge thereto. The compression of the fuel charge takes place during approximately the last three-quarter instroke of the fast moving piston, or during approximately a 135 movement of its crank, and also while the slow piston is making the last half of its instroke which is while its crank is making the 90 movement from the position shown in Fig. 4 to that in Fig. 1.

In the present instance, fuel is directed to the port is through a supply passage I8 and air is directed to the port I! through a passage l9. These two passages have communication at their inner ends with a common passage 20 into which air is blown by a blower 2|, or in any other suitable manner. Liquid fuel is blown or drawn by suction action into the fuel passage l8 from a carburetor 22 through a nozzle 28 projected into said passage. It is thus apparent that when the fuel valve I8 is open. air from the passage 20 passes through the branch passage l8 carrying with it a fuel charge from the carburetor 22, and this commingled air and fuel charge enters the chamber 28 where ignition preferably occurs. when the air valve i8 is open, an air charge from the branch passage l8 passes through the port l4 into the chamber l2 and thence passes either alone or with the fuel charge into the combustion chamber through the port ll. Ignition preferably takes place in the fuel receiving end of the chamber l2 by the sparking of a spark plug 24 therein, or in any other suitable manner. This causes ignition to take place in the portion of the chamber l2 in which the mixture is the richest and has not been diluted by air admitted to the passage end portion of the chamber.

The means illustrated for operating the two valves 18 and [8 at proper points in a cycle of operations comprises two cams 28|and 28, respectively, mounted on a shaft 21 (Fig. of the center gear of/the train 8, which gear turns at the same speed as the crank shaft I. The cam 28 operates a push-rod 28 that is connected to and operates a bell-crank lever 28, which in turn is connected to a bell-crank lever 80 serving as a tappet for engaging the stem of the fuel valve l8 and imparting an opening movement thereto against the tension of the valve spring 8|. Likewise, the cam 28 operates a tappet rod 82 connected to a bell-crank lever 88 which has connection with a tappet lever 84 acting on the stem of the air valve N. This air valve is also normally retained in closed position by a spring II. In the present instance, the means or frame part 88, which forms the passages l8, l8 and 20, is of loop-form to provide a central opening 38 in which the upper ends of the valve stems, the springs 8| and the tappet levers 80 and 84 are mounted, the levers 28 and 88 being fulcrumed between bracket arms 81 (Fig. 5) projecting from one side of said frame part.

Any novelty in the manner shown and described herein for controlling the separate admission of the air and fuel charge to the cylinder through the auxiliary chamber I2 is claimed in 5 my co-pending application Serial No. 699,327,

filed September 25, 1946.

It is apparent that during the instroke of the slow moving piston 8, which is from the position shown in Fig. 3 to that in Fig. 1, a 180 movement of its crank 2, the crank of the fast moving piston, is making a complete revolution, or 360", thus causing the fast piston 4 to make both a complete out and a complete in stroke. This outstroke of the fast piston, due to its greater speed of movement than the slow piston 8, creates a partial vacuum in the cylinder, tending to draw the fuel charge therein while the valve I6 is open, and to agitate and mix the fuel charge with the air charge in the cylinder while the instroke of the fast piston from the position shown in Fig. 4 to that in Fig. 1 cooperates with the slow moving piston to compress the charge in the cylinder, preparatory for combustion, which later may be effected either by sparking in the conventional way or by compression as in the Diesel type of engines. It will, of course, be understood that fuel'injection, whether of Diesel or low pressure type, takes place every revolution of the crankshaft I, and every other revolution of crankshaft 8.

In the operation of the engine, ignition takes place or starts before the crank of the slow moving piston 8 reaches its top or inward center and after the crank of fast moving piston 4 has started toward its outward center position. The explosion pressure will bring the two cranks in approximately the positions shown in Fig. 2, the crank 8 having traveled approximately 180 and the crank 1 approximately 90. The pressure of the explosion will move the crank 8 approximately 45 past outer dead center due to the great leverage exerted by the slow moving crank 1 near the end of its power stroke, which stroke constitutes the first half of the outward movement of the slow moving piston 8. The exhaust port ll 45 starts to open at the end of the power strokes of the two pistons or when the crank of the slow moving piston is approximately one-half the distance between its inner and outer dead centers, and the port remains open until said slow crank 60 has approximately completed 180 of movement from initial port opening position. The air valve starts opening approximately coincident with the initial uncovering of the exhaust port and the air thus admitted sweeps the burnt gases toward the 55 exhaust port. The air continues to flow into the cylinder until the slow moving piston has approximately completed its outstroke or during approximately a 90 movement of the crankshaft I. The fuel valve starts to open approximately at 00 the time of closing of the air valve, which is at approximately the outer dead center of the slow crank, and remains open until the slow piston has traveled inward approximately 90 of its crank movement at which time the exhaust port is 68 closed by the piston 8 and the compression of the charge then takes place during the remaining inward stroke of the. slow piston and for approxi-. mately a 180 movement of the fast moving crank or until the pistons and their respective cranks 70 have moved from the positions shown in Fig. 4 to those in Fig. 1 when the parts are again in position for the firing of a charge.

Important advantages of the present invention over the ordinary engine as well as that disclosed 75 in my said prior Patent 2,345,056 are the obtaining of a longer power stroke, an exhaust port of larger area, a longer dwell or opening of the exhaust port, and a longer time for the admission of of a charge, the power stroke taking place over approximately 180 of movement of the fast piston shaft, the exhaust taking place over approximately the next 180 of movement of said shaft and the fuel charge taking place over approximately 180 of movement of the shaft, thus materially increasing the engine efliciency. Also the engine ignition takes place slightly before the crank of the slow piston 5 reaches its inner dead center position and when the crank of the fast piston 4 is past its dead center position. As crank 6 is th fast traveling crank'and has a two-to-one leverage over crank 1 any explosion pressure will turn the crankshafts in the direction of rotation even though the slow piston 5 has not reached its outer dead center position. Furthermore, with this engine it is not necessary to use a high charging pressure because the fast traveling piston assists in scavenging as well as charging the engine.

I wish it understood that my invention is not limited to any specific construction, arrangement or form of the parts, as it is capable of numerous modifications and changes without departing from the spirit of the claims.

Having thus described my invention, what I claim 'as new, and desire to secure by United States Letters Patent, is:

1. An internal combustion engine having a cylinder in which two opposing pistons operate and between which combustion occurs, said pistons being connected at opposite ends of the cylinder to separate crankshafts geared together with a two-to-one ratio, with the slow moving piston controlling an exhaust port, wherein the fast moving piston has a crank lead over the slow piston at the firing position, and the exhaust port is located so that the slow piston starts to uncover it when approximately midway of its outstroke.

2. An internal combustion engine having a cylinder in which two oppositing pistons operate and between which combustion occurs, said pistons being connected at opposite ends of the cylinder to separate crankshafts geared together with a two-to-one ratio, with the slow moving piston controlling an exhaust port, wherein the fast moving piston serves as the main power piston and has a crank lead over the other piston at the firing position, and the exhaust port is located and of such area that the slow piston starts to uncover it when approximately midway of its outstroke and continues to uncover it until the piston has returned to approximately such midway position.

3. An internal combustion engine having a cylinder in which two opposing pistons operate and between which combustion occurs, said pistons being connected at opposite ends of the cylinder to separate crankshafts geared together with a two-to-one ratio, with the slow moving piston controlling an exhaust port, wherein the fast moving piston has a crank lead of approximately 45 over the slow piston with a power stroke of approximately 180, and the exhaust port is located to be uncovered by the slow piston when approximately midway of its outstroke and continues uncovered. until the slow piston has returned to such position.

4. An internal combustion engine having a cylinder in which two oppq ing pistons operate and between which combustion occurs, said pis-' tons being connected at opposite ends of the cyl- 6 inder to separate crankshafts geared together with a two-to-one ratio, with the slow moving piston controlling an exhaust port, wherein the fast moving piston has a crank throw lead over the slow piston, and the exhaust port is located so that the slow piston starts to uncover it when approximately midway of the outstroke, together with means to admit an air charge to the cylinder approximately coincident with the opening of the exhaust port and continuing to approximately the end of the outstroke of the slow piston.

5. An internal combustion engine having a cylinder in which two opposing pistons operate and between which combustion occurs, said pistons being connected at opposite ends of the cylinder to separate crankshafts geared together with a two-to-one ratio, with the slow moving piston controlling an exhaust port, wherein the fast moving piston has a crank throw lead over the slow piston, and the exhaust port is-located so that the slow piston starts to uncover it when approximately midway of its outstroke, together with means to admit an air charge to the cylinder approximately coincident with the opening of the exhaust port and continuing to approximately the end of the outstroke of the slow piston, and means for admitting a fuel charge starting at approximately the beginning of the instroke of the slow piston and continuing for approximately half of such stroke.

6. An internal combustion engine having a cylinder in which two opposing pistons operate and between which combustion occurs, said pistons being connected at opposite ends of the cylinder to separate crankshafts geared together, with a two-to-one ratio, with the slow moving piston controlling an exhaust port, wherein the crank of thefast. piston is approximately 45 past inner dead center when th crank of theslow piston is at inner dead center and the slow'piston starts to uncover the exhaust port when approximately midway of its outstroke and continues such uncovering for the remainder of such stroke,

means to admit an air charge to the cylinder during approximately the last half of the slow piston outstroke, and means to admit a fuel charge to the cylinder during approximately the first half of the slow piston instroke.

7. An internal combustion engine having a cylinder in which twoopposing pistons operate and between which combustion occurs, said pistons being connected at opposite ends of the cylinder to separate crankshafts geared together with a two-to-one ratio with the slow moving piston controlling an exhaust port, wherein the fast moving piston has a crank throw lead over the slow piston and the exhaust port is located so that the slow piston starts to uncover it when approximately midway of its outstroke and continues such uncovering until the piston has approximately completed its outstroke, together with means for introducing first an air charge and then a fuel charge to the central portion of the cylinder during approximately the period of uncovering of the exhaust port.

8. An internal combustion engine having a cylinder in which two opposing, pistons operate and between which combustion occurs, said pistons being connected at opposite ends of the cylinder to separate crankshafts geared. together with a two-to-one ratio, with the slow moving piston controlling an exhaust port, wherein the crankshafts'tum in counterclockwise direction and the fast moving piston has a crank throw 76 lead over the slow piston and the exhaust port 7 is located so that the slow piston starts to uncover it when approximately midway of its outatroke and continues such uncovering until the piston has approximately completed its outstroke, together with means for introducing first an air charge and then a fuel charge to the central portion of the cylinder during approximately the period of uncovering oi. the exhaust port.

MARION MALLORY.

REFERENCES CITED The following references are of record in the file of this patent:

Number Number UNITED STATES PATENTS Name Date Fite et a1 May 4, 1920 Junkers Feb. 18, 1938 FOREIGN PATENTS Country Date Great Britain 1924 France 1939