US2543851A - Free piston machine - Google Patents

Description

H. B. HORGEN FREE PISTON MACHINE Filed April 11, 1945 g o INVENTDR A ATTORN E Y5 Patented Mar. 6, 1951 FREE PISTON MACHINE Helge Bodvar Hon-gen, Lyon, France, assignor, by direct and mesne assignments, of nine-tenths to Raul Pateras Pescara, Lisbon, Portugal. and one-tenth to Societe dEtudcs et de Participations, Eau, Gaz, Electricite, Energie S. A. Geneva, Switzerland, a society of Switzerland Application April 11, 1945, Serial No. 587,695 In France May 30, 1944 7 Claims. 1

The present invention relates to free piston machines, and especially motor compressors and auto generators of the free piston type, these machines including at least one movable system constituted by a motor piston rigid with at least one compressor piston, the expression compressor piston designating", in this case, as well a piston serving for the actual delivery of compressed gas as a piston coacting with a cylinder containing a cushion of gas acting as an energy accumulator for ensuring the return displacements of this movable system, or else a piston performing both of these functions.

The application of the present invention is particularly interesting in the case of free piston 'machines, and especially auto generators, in

which the cylinder coacting with the compressor piston and the air reservoir for the feed of the motor cylinder are contiguous to each other, discharge valves being provided in the wall that separates said first mentioned cylinder from said reservoir.

The object of the present invention is to pro- ,vide a machineof the type above set forth in which the movable system is better guided than in machines made up to this time.

A preferred embodiment of my invention will be hereinafter described, with reference to the accompanying drawings, given merely by way of example, and in which:

Fig. 1 is a diagrammatic axial sectional view of a free piston auto generator made according to the present invention; and

Figs. 2 to 4 show certain elements of the eccentric guiding means of the compressor piston of said auto generator.

This auto generator includes a motor cylinder 1 surrounded by acasing 2 acting as feed air reservoir for said cylinder. The wall of cylinder I is provided with inlet ports 3 and outlet ports t. opened by pistons 5 and 5' when said pistons are at the ends of the outward strokes.

Compressor pistons 6 and 6', of larger diameter than the corresponding motor pistons, and adapted to coact with cylinders 1 respectively, are rigidly associated with each of said motor pistons. The combination of a motor piston and the corresponding compressor piston constitutes what is called, in the present specification, a movable system. The two movable systems, symmetrical with respect to each other, of the auto generator shown in the drawing have opposed movements and are interconnected by synchronizin means, not shown by the drawing.

Each of the cylinders l is closed, on the outer side, by a cylinder head 8, and on the inner side, by an annular partition 9.

The variable volume chambers formed, in cylinders 'l, on the outer sides of the compressor pistons constitute energy accumulators for ensuring the return strokes of the movable systems toward the center, owing to the energy stored up in the air cushions present in these chambers during the outward strokes of said movable systems.

The variable volume chambers formed, in cylinders l, on the inner sides of the compressor pistons are fitted with inlet valves I2 and discharge valves l3, these valves l3 being advantageously located in partitions 9 in such manner as to feed the air compressed by pistons 66' into casing 2, located between partitions 9. Com-- cally mounted rods 20, fixed in position and parallel to the common axis of the cylinders, each of these rods extending with a snug fit through a slide member 2| provided in the corresponding compressor piston of each movable system.

Preferably, said slide member 2i is mounted in such manner as to permit a limited relative radial displacement thereof with respect to the corresponding compressor piston 6-6, so as to make allowance for free expansion thereof. Furthermore, packing means are provided for preventing leakage from one side to the other of the compressor piston.

For these purposes, in the embodiment illustrated in the drawings (Figs. 2 to 4), slide member 2| is provided with two plane faces Zia, parallel to the axial plane of the corresponding piston 6-6 that passes half way between them, and adapted to coact with corresponding guiding surfaces 33 rigid with said piston. The guiding surfaces 33 in question are carried by a cap 34, the shape of which is shown by the perspective view of Fig. 4, and which, under the efiect of tightening means, for instance screws 34a engaged in a sleeve 36, applies the desired pressure on the packing 35 of a stufiing box adapted to ensure a fiuidtight joint around tube 20. The

aeaassi in sleeve 36 fitted in piston 6-5.

Preferably, each rod 29 is fixed only at one end, to wit, the inner end, to the corresponding annular partitions a, and it extends sumciently far on the outer side for constantly guiding the compressor piston whatever be the length of stroke thereof.

Advantageously, the two rods 20 of a, given machine, which may be disposed in line with each other, are constituted by tubes open at both ends, the inner ends of these tubes being connected together through a tube 20a located on the inside of casing 2. The whole of tubes 20 and 20a thus constitutes a single conduit which permanently connects together the two energy accumulators located at the respective ends of the machine.

With such an arrangement, that is to say with a permanent communication thus ensured between the two energy accumulators, a single starting device 22 is sufiicient for feeding starting air to the respective air cushion spaces of said accumulators. This starting device may be connected to tube 20a, which is, in this case, provided with suitable ports 23, inside casing 2, as shown in dotted lines by the drawing.

The machine shown by the drawing is fitted, in each cylinder 1, in addition to the eccentric guiding rod 20, with a rod II located along the common axis of the cylinders and fixed to the end 8 of cylinder I. These rods II are slidably engaged with housings I provided on the inside of the corresponding movable system, axially with respect thereto. Each movable system includes, preferably close to its outer end, a seat slidable along the outer surface of rod II, so as thus to ensure, in combination with eccentric rod 20, the axial guiding of said end, while the inner end of said movable system is guided by the motor cylinder I.

Advantageously, a pivot joint, and preferably a ball and socket joint as shown at I4, is interposed between rod ii and the movable system which includes piston 6-6'. Owing to the presence of this joint, I eliminate any possibility of jamming or friction as might be caused by misalignment of the axes of housing Ill and rod Ii.

Preferably, rod Ii is hollow and thus constitutes a tube. In this case, I may provide, at the free end of this tube, a stuiiing box I5, inside which is slidably mounted, in a fluid-tight manner, a sleeve it open at both ends and assembled with the end of piston 6 or 5 in such manner that the inside of said sleeve communicates with a recess II provided on the inside of said cylinder end. Furthermore, on the inside of tube II is fixed a conduit i8 engaged with a suilicient annular clearance in sleeve IS. The free open end of this conduit i8 is located, when the corresponding piston is at the end of its outward stroke, close to recess I'I, so that, if a cooling liquid is injected through this conduit I8, this liquid flows into recess II and then flows back through sleeve I6 and tube I I, to be finally evacuated through a suitable outlet passage I9.

Advantageously, a pivot joint is included in the means for axially guiding the motor piston. For this purpose, a portion of the outer wall of said piston is constituted by a cylindrical element 30 made of two halves and the external cylindrical surface of which coacts with the inner cylindrical surface of the motor cylinder. The inner part of this element forms a hollow spherical surface 3| which engages a corresponding surface 32 provided on the motor piston. Surfaces 35-32 constitute a ball and socket joint included in the motor piston axial guiding means. In order to facilitate assembly, each motor piston il-h is made of three portions to, 5b and 5c. Portion Ida includes the piston end and cavity ll. Portion 5c is directly attached to the corresponding compressor piston, and portion 617 serves to connect portions 5a and So together. The spherical surface 32 that carries cylindrical guiding element 30 is formed on this intermediate portion Eb.

On the drawing, the machine has been shown as being symmetrical, but this is not necessary.

What I claim is:

1. A free piston machine which comprises, in combination, a motor cylinder, two freely movable motor pistons adapted to work in opposed directions in synchronism with each other in said cylinder, a compressor piston rigid with each of said motor pistons on the outer side thereof and in coaxial relation therewith, a cylinder adapted to coact with each of said compressor pistons, the outer end of each of said last mentioned cylinders being closed so as to form, with the outer face of the corresponding compressor piston, a pneumatic cushion chamber adapted to act as energy accumulator, a guiding tube mounted in fixed position in each of said last mentioned cylinders, parallel to and at a distance from the axis thereof, said tube extending with a snug fit through the corresponding compressor piston and opening into the corresponding energy accumulator chamber, and tube means for interconnecting the open ends of said guiding tubes located on the other sides from said chambers with respect to said compressor pistons, respectively.

2. A free piston machine which comprises, in combination, a motor cylinder, two freely movable motor pistons adapted to work in opposed directions in synchronism with each other in said cylinder, a compressor piston rigid with each of said motor pistons on the outer side thereof and in coaxial relation therewith, a cylinder adapted to coact with each of said compressor pistons, the outer end of each of said last mentioned cylinders being closed so as to form, with the outer face of the corresponding compressor piston, a pneumatic cushion chamber adapted to act as energy accumulator, a guiding tube mounted in fixed position in each of said last mentioned cylinders, parallel to and at a distance from the axis thereof, said tube extending with a snug fit through the corresponding compressor piston and opening into the corresponding energy accumulator chamber, a compressed air feed reservoir for said motor cylinder surrounding the latter, and tube means in said reservoir for interconnecting the open ends of said guiding tubes located on the other sides from said chambers with respect to said compressor pistons, respectively.

3. A free piston machine which comprises, in combination, a motor cylinder, at least one freely movable motor piston in said cylinder, at least one compressor piston rigid with said motor piston coaxially therewith, a cylinder adapted to 'coact with said compressor piston, a guiding rod mounted in fixed position in said last mentioned cylinder, parallel to and at a distance from the axis thereof, said rod extending with a snug sliding fit through said compressor piston, an axial guiding rod carried by the outer end of said second mentioned cylinder, the unit formed by said two pistons being provided with an axial housing for slidably accommodating said last mentioned rod, and a pivot joint interposed between said axial rod and a portion of said unit.

4. A free piston machine which comprises, in combination, a motor cylinder, at least one freely movable motor piston in said cylinder, a compressor piston rigid with said motor piston on the outer side thereof and in coaxial relation therewith, a cylinder adapted to coact with said compressor piston, an axial tubular rod carried by the second mentioned cylinder and extending inwardly toward said motor cylinder, said compressor and motor pistons being provided with an axial housing for accommodating said rod, the end of said motor piston being provided with a recess, an axial sleeve carried by said motor piston inside said housing and communicating at one end with said recess, the other end of said sleeve being slidable with a fiuidtight fit on the inner end of said tubular rod, and a conduit extending axially in said tubular rod and said sleeve, with an annular clearance around it, for circulation of a cooling liquid stream through said conduit, said recess of the motor piston and the annular interval between said conduit and said rod and sleeve.

5. A free piston machine which comprises, in combination, a motor cylinder, at least one freely movable motor piston in said cylinder including a central portion and at least one peripheral cylindrical portion axially guided in said cylinder, a pivot joint between the peripheral and central portions of said motor piston, at least one compressor piston, on the outer side of said motor piston, rigid with said central portion thereof in coaxial relation with said central portion, and a compressor cylinder adapted to cooperate with axially guiding the unit formed by said two pistons with respect to said compressor cylinder, said last mentioned means including an axial rod carried by said compressor cylinder extending toward said motor cylinder, a part slidable along said rod, and a pivot joint between said part and said unit, and a fixed guiding rod parallel to and at a distance from the axis of said compressor piston, said last mentioned rod extending with a snug sliding fit through said compressor piston.

7. A free piston machine which comprises, in combination, a motor cylinder, at least one freely movable motor piston in said cylinder, at least one compressor piston rigid with said motor piston and provided with at least one eccentric longitudinal passage extending throughout its length, a cylinder adapted to coact with said compressor piston, at least one guiding rod fixed to said last mentioned cylinder, parallel to and at a distance from the axis thereof, extending through said passage, a tubular member arranged to fit snugly on said rod in said passage, said member having plane walls parallel to the axial plane of the compressor piston that passes through the axis of said tubular member, an end plate secured to said piston and provided with extensions having inner plane walls adapted to cooperate with said plane walls of the tubular member for the radial guiding of said member with respect to said compressor piston, and packing means in said passage adapted to cooperate with said rod.

HEDGE BODVAR HORGEN'.

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

UNITED STATES PATENTS Number Name Date 1,747,948 Pescara Feb. 18, 1930 2,028,331 Janicke Jan. 21, 1936 2,077,802 Martin Apr. 20, 193"! 2,178,310 Pescara Oct. 31, 1939 FOREIGN PATENTS Number Country Date 426,693 Great Britain Apr. 8, 1935 770,023 France June 18, 1934

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