US3283752A

US3283752A - Free piston machine

Info

Publication number: US3283752A
Application number: US365211A
Authority: US
Inventors: Stelzer Frank
Original assignee: Individual
Current assignee: Individual
Priority date: 1963-05-06
Filing date: 1964-05-05
Publication date: 1966-11-08
Anticipated expiration: 1983-11-08
Also published as: DE1451662A1; AT274475B

Description

Nov. 8, 1966 F. STELZER 3,

FREE PISTONMACHINE FiledMay s, 1964 ZSheetS -Sheet 2 INVENTOR United States Patent 3,283,752 FREE PISTON MACHINE Frank Stelzer, Elbestrasse 59, Raunlieim, near Frankfurt, Germany Filed May 5, 1964, Ser. No. 365,211 Claims priority, application Germany, May 6, 1963, H 49,061; Oct. 7, 1963, St 22,364 2 (Ilaims. (Cl. 123-46) The present invention relates to a free piston machine, and more particularly to a free piston machine operating according to the two cycle principle and being a combined prime mover and engine.

It is one object of the present invention to provide a combustion engine which is particularly suited for propelling vehicles or for driving other machines.

Another object of the invention is to provide a free piston of simple and economical construction which reliably operates.

Another object of the invention is to provide a free piston machine in which moving mechanical parts, such as cranks, connecting rods and crank shafts are omitted.

Another object of the invention is to provide a machine with a movable element which is driven to produce power which is partly used for doing work.

With these objects in view, the present invention relates to a free piston machine which operates on the two cycle principle, and compresses a gaseous fuel before the same is ignited.

One embodiment of the invention comprises cylinder means having two cylinder spaces separated by a transverse wall; a piston means including two pistons located in the cylinder spaces and a connecting portion of smaller diameter passing through an opening in the transverse Wall.

Each piston forms in the correlated cylinder space a compression chamber and a combustion chamber con tracting and expanding during reciprocation of the piston means.

Means for supplying fuel into the compression chan1- bers, means for exhausting burned gases from the combustion chambers, and passage means for connecting each compression chamber with a combustion chamber are provided.

In the preferred embodiment of the invention, the two pistons have the same diameter, and the connecting portion between the pistons, as well as two end portions of the pistons have a smaller, and preferably equal diameter. The end portions of the piston are advantageously guided in cylinder portions at the ends of the cylinder means, and may be used as pump or compressor pistons.

In another embodiment of the invention, the entire piston means has an inner axially extending cavity narrower at one end than at the other end, and preferably provided with a check valve, so that a fluid supplied to the wider end of the cavity will be compressed or accelerated at the narrower end ofthe cavity when the piston means is reciprocated.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompariying drawings, in which:

FIG. 1 is a diagrammatic cross-sectional view illustrating the shape of a cylinder means and piston means in accordance with the principle of the present invention;

FIG. 2 is an axial sectional view of one embodiment of the invention, conventional elements being schematically illustrated for the sake of simplicity; and

Patented Nov. 8, 1966 FIG. 3 is an axial sectional view illustrating another embodiment of the invention.

Referring now to the drawings, and more particularly to FIGS. 1 and 2, a cylinder means 12 has walls which define an inner cavity 10 in which a piston means 14 is disposed for axial reciprocating movement. Piston means 14 has two pistons 18, a connecting portion 16 of smaller diameter than pistons 18, and two cylindrical end portions 20 located in cylinder portions which define cylinder chambers 28. The two cylinder spaces of larger diameter formed by the cylinder means 12 are respectively divided by the pistons 18 into axially outward located combustion chambers 26, and axially inward located compression chambers 24. The connecting portion 16 of piston means 14 is slidably guided in an opening 22 and, as shown in FIG. 2, piston rings 40 on connecting portion 16 prevent communication between compression chambers 24. Piston rings 40 are also provided on pistons 18 so that each compression chamber is separated from the correlated combustion chamber located in the same cylinder space.

The cylinder spaces 28 are closed by transverse end walls in which inlet valve means 44 and outlet valve means 46 are located.

In each combustion chamber 26, igniting means 42, such as a sparkplug, or a member permanently heated by the heat of the combustion, are provided.

An outlet 38 for discharging combustion gases is pr0- vided in each combustion chamber spaced from the igniting means 42 in axial direction so that the respective outlet 38 is closed when piston 18 is in the position shown for the left piston in FIG. 2.

An inlet means 30 for fuel, or fuel-air mixture, or other suitable fluid, is provided in each compression chamber 24 adjacent the respective outlet means 38.

A passage 34 connects each compression chamber 24 with the correlated combustion chamber 26, and has a slot-shaped port 32 in the respective compression chamber adjacent the central wall, and a slot-shaped port 36 which opens into the respective combustion chamber.

The inlet means 30 are connected with a conventional fuel carburetor or fuel injection device, not illustrated.

The machine operates in the following mannerz The combustion chamber 26 on the left of FIG. 2 is contracted to the minimum volume since the piston means is in its left dead center position, or shortly before the same. When the igniting means 42 have ignited the-com pressed fuel in combustion chamber 26, or if the com pressed fuel was ignited without igniting means due to its great volatility, for example, gasoline, piston means 14 is driven to the right as viewed in FIG. 2.

The left piston 18 first closes the inlet 30, then compresses the gaseous fuel in compression chamber 24, and finally presses the fuel through passage 34'when piston 18 has travelled far enough to uncover port 36 of passage 34. The fuel flows in compressed condition into combustion chamber 26.

During the same stroke the piston means 14 moves the right piston 18 to the right to first close the outlet 38 and port 36, and to then compress the already pre-compressed fuel in the right combustion chamber 26 until arriving in the right dead center position where the compressed fuel in the right combustion chamber 26 is ignited.

At the same same, the right piston 18 uncovers the inlet 30 so that a fresh fuel mixture can enter the right compression chamber 24. At the same time, the left piston 18 has arrived in its right dead center position closing port 32. In this manner, the piston means 14 is reciprocated in two cycles.

The end portions 20 of the piston means reciprocate at the same time in the correlated cylinder chambers 28, and it will be understood that a fluid entering through inlet valves 44 during movement of the piston means in one direction will be discharged through outlet valves 46 during a reciprocating stroke of the piston means in the opposite direction. Since the discharge from the two pump chambers 28 takes place alternately, a fairly constant flow is assured.

FIG. 3 illustrates a modified embodiment of the invention, and corresponding parts are indicated by like reference numerals. The pump chambers 28 are omitted, and opeen cylinder portions 49 provided at the ends of cylinder means 12. The piston means 14' is provided with longer end portions 50 which project out of the cylinder portions 49. The piston means 14' has an inner frusto-conical cavity 48 wider at the right end and narrower at the left end of piston means 14, a short wider portion 52 being provided at the narrow end of cavity 48.

When the piston is reciprocated due to the combustion of gases in the combustion chambers 26, a fluid medium surrounding the right end of piston means 14' will be compressed or accelerated in cavity 48 while piston means 14 moves to the right. A check valve 53 arranged in cavity 48 prevents the return of fluid during the stroke in the opposite direction so that the fluid is pumped from the wider open end 50 to the narrower end 52 of the cavity.

As compared with conventional two cycle motors with slot-shaped ports and transverse flow of the air, the machine of the invention has great advantages inasmuch as no connecting rods and crankshafts are required, and a single piston means operates in two combustion chambers to be driven during opposite strokes. The moving mass is small, and consequently a higher degree of compression, and a more exact timing can be achieved than with conventional two cycle motors, particularly since the pre-compression takes place only in the compression chambers 24, whereas in known constructions, the precompression is effected also within a crankshaft case. The compression chambers 24, in which the fuel is precompressed, have an exactly determined volume.

The power given to the piston means by the combustion of the fuel is transformed into work by the piston end portions or by the direct action of the piston means, as explained with reference to FIG. 3. A single piston means is driven, and also operates to pump a liquid, or to compress a gas. Of course, the power of the reciprocating piston means may be used in any other suitable manner. In the embodiment of FIGS. 2 and 3 where a fluid is pumped, the fluid may be supplied to turbines, for example, to turbines located in the wheels of a vehicle so that all wheels are driven from the two cycle combustion engine of the invention.

In order to start the machines according to the invention, the operation is reversed, and a compressed fluid, for example, compressed air is supplied in intermittent and alternating thrusts into the chambers 28 of the machine so that the piston means is reciprocated and compresses the fuel mixture to start the regular operation.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of free piston machines differing from the types described above.

While the invention has been illustrated and described as embodied in a two cycle free piston double-acting combustion engine, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

l. A two cycle free piston machine comprising, in combination, a cylinder means having wall means forming two cylinder spaces having the same diameter, said wall means including a transverse wall separating said two cylinder spaces and having an opening connecting said cylinder spaces, said cylinder means including two cylinder portions at the ends thereof coaxial with said cylinder spaces; a piston means including two pistons having the same diameter and being respectively located in said cylinder spaces, two cylindrical end portions slidable in said cylinder portions of said cylinder means, and a connecting portion having a smaller diameter than said pistons and passing through said opening in said transverse wall,-each piston forming in the correlated cylinder space a compression chamber and a combustion chamber, said chambers contracting and expanding during reciprocation of said piston means; inner conical cavity means References Cited by the Examiner UNITED STATES PATENTS 735,863 8/1903 Duryea et a1 123-46 1,405,551 2/1922 Nichols 123-46 1,741,731 12/1929 Nordensson 23056 2,067,358 1/1937 Thornton 23035 2,178,310 10/1939 Pescara 230-56 3,170,406 2/ 1965 Robertson 103-54 FOREIGN PATENTS 827,407 2/ 1960 Great Britain.

MARK NEWMAN, Primary Examiner.

WENDELL E. BURNS, Examiner.

Claims

1. A TWO CYCLE FREE PISTON MACHINE COMPRISING, IN COMBINATION, A CYLINDER MEANS HAVING WALL MEANS FORMING TWO CYLINDER SPACES HAVING THE SAME DIAMETER, SAID WALL MEANS INCLUDING A TRANSVERSE WALL SEPERATING SAID TWO CYLINDER SPACES AND HAVING AN OPENING CONNECTING SAID CYLINDER SPACES, SAID CYLINDER MEANS INCLUDING TWO CYLINDER PORTIONS AT THE ENDS THEREOF COAXIAL WITH SAID CYLINDER SPACES; A PISTON MEANS INCLUDING TWO PISTONS HAVING THE SAME DIAMETER AND BEING RESPECTIVELY LOCATED IN SAID CYLINDER SPACES, TWO CYLINDRICAL ENDS PORTIONS SLIDABLE IN SAID CYLINDER PORTIONS OF SAID CYLINDER MEANS, AND A CONNECTING PORTION HAVING A SMALLER DIAMETER THAN SAID PISTONS AND PASSING THROUGH SAID OPENING IN SAID TRANSVERSE WALL, EACH PISTON FORMING IN THE CORRELATED SPACE A COMPRESSION CHAMBER AND A COMBUSTION CHAMBER, SAID CHAMBERS CONTRACTING AND EXPANDING DURING RECIPROCATION OF SAID PISTON MEANS; INNER CONICAL CAVITY MEANS EXTENDING FROM ONE OF SAID CYLINDRICAL END PORTIONS TO THE OTHER OF SAID CYLINDRICAL END PORTIONS AND BEING WIDER AT ONE END THAN AT THE OTHER END THEREOF WHEREBY DURING RECIPROCATION OF SAID PISTON MEANS A FLUID CAN BE COMPRESSED IN OR PUMPED THROUGH SAID CAVITY MEANS; MEANS FOR SUPPLYING FUEL INTO SAID COMPRESSION CHAMBERS; MEANS FOR EXHAUSTING GASES FROM SAID COMBUSTION CHAMBERS; AND PASSAGE MEANS FOR CONNECTING EACH COMPRESSION CHAMBER WITH THE CORRELATED COMBUSTION CHAMBER.