US2581600A - Free piston motor compressor - Google Patents

Description

Jan.'8, 1952 R. PATERAs PESCARA FREE PISTON MOTOR COMPRESSOR Original Filed Nov. 25, 1941 3 Sheets-Sheet 3 IN VE N TUR M zzw. f

ATTORNEY Patented Jan. 8, v1952 z, 5s1,6on

FREE PIsToN Mo'roR COMPRESSOR v Raul Pateras Pescara, Paris, France, assignor to Societe dEtudes vet de Participations, Eau, Gaz, Electricite, Energie, S. A.,'Geneva, Switzerland, a society of Switzerland Continuation o! application Serial No. 420,432,

This application August 30, 1946, Serial No. 693.8844.r In France Septem- November 25, 1941.

bei' 3, 1941 12 Claims. l

The present application, which is a continua-f tion of my U. S. patent application Ser. No. 420,432, tiled November 25, 1941, now abandoned, the latter being a continuation in part of my U. S. patent application Ser. No. 182,865, filed December 31, 1937, now abandoned, relates to freepiston motor-compressors, that is to say machines including at least one motor part and at least one compressor part, and the recipro-V cating element or elements of which move with a length of stroke which is variable within certain limits, at least the main portion of the air compressed by the compressor part of the motorcompressor serving to feed a receiver, for instance a compressed air reservoir, an air turbine, and so on, distinct from the motor-compressor itself.

Said motor-compressors which deliver compressed air directly from the compressor cylinder or cylinders thereof to the outside of the motor-compressor must not be confused with freel piston auto-generators wherein the whole of the air compressed by their compressor part ows through the motor cylinder for scavenging this cylinder and mixing with the combustion gases thereof, this gaseous mixture fed from the Preferred embodiments of the present invention will be hereinafter described, withreierence to the accompanying drawings, given merely by way of example, and in which:

Fig. 1 is a diagrammatical view of a free pistony motor-compressor made according to a first embodiment of the present invention;

Fig. 2 shows a diagram illustrating the working of this machine;

Fig. 3 is a view, similar to Fig. 1, showing a second embodiment of the invention; and

Fig. 4 is a view, similar to Figs. 1 and 3, shoW- ing a third embodiment of the invention.

In the following description, it will be supposed thatthe invention is applied to the case of a free piston motor-compressor having a single action motor part which works on the two.- stroke principle.

Concerning the general construction of the motor-compressor, it is of any suitable known type. For instance, according to the embodiment illustrated by Figs.- 1 and 3, it includes a motor cylinder I cooperating with two pistons 21 motor cylinder of the auto-generator constituting the final product of the same.

- Anong the motor-compressors thus defined, it is necessary to make a distinction between those in which both the outward and the inward strokes are producedby the combustion of fuel in a motor element, these machines therefore having a double action motor system, and those in which some of these strokes, for instance the outward strokes are produced by the combustion of fuel in a motor element, while the inward strokes are produced by elastic means, in particular by pneumatic cushions capable of storing up, during the outward strokes, a certain amount of energy which is subsequently restored to the free pistons for producing their inward strokes. In this latter case, the machines have a single action motor system.

v.Ihe invention is more especially, although not exclusively concerned, among these machines. with those having a single action motor system.

The principal object of the invention is to provide a free piston motor-compressor capable of undergoing great load variations, corresponding either to pressure variations of the air delivered `to the outside of the machine, or to variations of the amount of air supplied on every piston stroke obtained by varying the length of stroke, or to both variations at the saine time.

Iii

and 22, reciprocating in opposed directions, and adapted to uncover, when nearing the ends of their outstrokes, inlet ports 3 and exhaust ports I.

One of these motor pistons. for instance piston 21. is associated with a compressor piston 5 moving in a cylinder 6, this last mentioned piston ensuring, through its outer face, in the chamber 61 of said cylinder 6, the compression of the air to be produced by the motor-compressor and fed to the outside thereof, while the inner face of piston 5 compresses, in the chamber 62 of the same cylinder, the air to be fed to a fluid-tight casing 'I surrounding motor cylinder I.

The other motor piston, to wit 22, is rigid with a piston 8 moving in a cylinder 9 and which entraps, in this cylinder, an air cushion which stores up, during the outward stroke of the motor pistons, a certain amount of energy, which is given back to the pistons during their inward strokes, thus permitting said inward strokes to take place.

' 'I'he reciprocating structures '2L-5, on the one hand, and 22-8, on the other hand, are interconnectedy by synchronizing means, consisting. for instance, of a lever I0 oscillating about a xed axis Il and connected at its ends, throughconnecting rods I2, with the two reciprocating structures, respectively.

I provide,I for the feed of fuel to the motor cylinder I, an injection pump or the like I3, con-- arenoso through a system of levers M, and the quantita tive regulation member i of which is operated, for instance, in response to variations or the pressure of compressed airin reservoir iB fed by the chamber 61 of the compressor cylinder 8. Pump I3 is connected through a conduit il with theinjector i8 which opens into motor cylinder i.

In a motor compressor of the kind above de-l scribed. the maximum power is limited, on the one hand, by the power of the motor part there of, and, on the other hand, by the weight oi air which can be introduced into the main chamber 61 of the compressor cylinder.

In order to increase the power of a given motor-compressor of this type. it is necessary to supercharge both said chamber and the motor cylinder.

Considering more particularly the supercharging of the motor cylinder, if the air to be fed to said cylinder for scavenging and combustion purposes were merely compressed by the inner face of compressor piston 5, it would be difficult to obtain high value and/or important variations of the pressure of said air.

On the other hand, in the case of a two-stroke engine, the utilization, for compressing the Jifeed and scavenging air. of a blower driven by gas turbine feed with the exhaust gases issuing from the motor cylinder would be generally insuicient for obtaining the necessary air pressures. in view of the fact that the exhaust gases issuing from` such an engine do not contain a suilicient amount of energy.

In order to avoid these drawbacks, I supercharge chamber 62, in which the inner face ci piston 5 compresses the feed and scavenging air to be fed to the motor cylinder, by means of a blower I8 which may also serve. to supercharge the main chamber B1 of the compressor part of the machine (see Fig. l). This blower I9 is driven by a gas turbine 2t fed with the exhaust gases passing through the exhaust part 4 of the motor cylinder l into the exhaust com duit.

The discharge pressure oi blower i9 is regulated by the variations of power of exhaust gas turbine 20. the power of which decreases when its inlet area ,increases for the following reasons:

When the input pressure of turbine 2d increases, blower IS delivers air at a higher pressure to compressor unit 5 6. The motor unit l--21-22 is therefore supercharged at a higher pressure and the number of reciprocations per unit of time of pistons 21-22 slightly increases. so that the mass of gases iiowing through turbine 2tl per unit of time slightly increases. But experiments have taught that this increase is very small and that, for practical purposes, the weight of gases flowing through turbine 2t can be considered as constant when the input pressure of turbine 2t varies.

On the other hand, it is known that for a turbine the output of which opens into the atmosphere, i. e. a medium at constant pressure, which is the case in the present instance, and through which the rate of flow by weight ci the exhaust gases remains practically constant, which, as above explained, is also the case, the power delivered by said turbine is the higher as the input pressure is higher. And it is perfectly clear that when the inlet area of the turbine is reduced, the pressure of the exhaust gases; which are compelled to ow through this area is increased.

position of this abutment 26 is chosen in such v manner that the inlet area of exhaust gas turbine 20 is minimum when piston 23 is applied against said abutment, and this is the `position shown by Fig. l.

The other face of piston 23 is subjected to the action of the pressure existing in reservoir I8. When this pressure increases above a given value, it produces a displacement oi piston 2lA toward the right and, consequently, an increase of the inlet area or turbine 2U, which, as above explained, corresponds to a reduction of the power of said turbine.

Preferably. I provide, on the exhaust pipe leading out .from port d a branch pipe 2l opening into the atmosphere and controlled by a valve 28, which, for certain conditions of operation, permits of discharging a certain portion of the exhaust gases directly into the atmosphere without passing them through turbine 20.

It follows that, when the power of turbine is maximum, and consequently when the load of the motor-compressor is maximum, the pressure in reservoir i6 is lower than that which exists therein when the machine is running on no load or with a low rate of delivery of the compressor. These two pressures determine the limits of regulation of the machine in question.

In the diagram of Fig. 2, I have shown, in solid lines and in dotted lines respectively, two different ways of operation of the motor-compressor, the diiierence between these methods of operation being due to diierent adjustments of the control device of turbine 20.

In the diagram of Fig. 2. the abscissas are the pressures existing in reservoir i6, while the ordinates represent, on the one hand. the rates 45 of delivery lQ into the main chamber 61 of the compressor cylinder and, on the other hand, the

delivery pressures p1 of blower is. The regulation zone thus ranges between the reservoir pressure p corresponding to the machine running 6o on maximum load and the reservoir pressure pb corresponding to the machine running on no load. As it results from the diagram of Fig. 2, the rate of delivery Q of the compressor cylinder is maximum when the load is maximum, while it 55 is minimum. or even equal to zero, when the load is zero.

According to the first of the two above mentioned methods of operation, the power of turbine 20, and consequently the compression obtained by means of blower i9, gradually de creases from the maximum value thereof (corresponding to a pressure pa in the reservoir i6) to the value when running on no load (corresponding to pressure pb in the reservoir It).

When running on no load (maximum value pb of the pressure in reservoir it), the turbo-blower system Ztl-i9 therefore delivers but little work and the feed pressure to chambers 61 and t2 is Vbut little higher than the atmospheric 70 pressure. When the amount of air withdrawn from reservoir i6 exceeds a given value, the drop of pressure in this reservoir produces a reduction of the inlet area of turbine 2t, due to a displacement oi slide valve 22, which corre- ?5 sponds to an increase of the pressure in the exhaust pipe of the motor and therefore to an increase of the'power of the turbo-blower system and of the feed pressure to the chambers 91 and 62 of the compressor.

When the regulation takes place according to the'modiiicat'ions illustrated. in the diagram of Fig. 2, by the dotted lines, I obtain a gradual variation of the feed pressure p1 from the blower within limits corresponding, on the one hand, to the maximum load of the motor-compressor and, on the other hand, to an intermediate load (for which the value of the pressure in reservoir lSis 12), while the feed pressure obtained from the blower remains substantially constant, at 'a' value but little above atmospheric pressure, ior values of the load ranging from this intermediate value to zero.

When the feed pressure obtained from blower I9 is close to the atmospheric pressure, the loss of power in the motor-compressor due to the working of the turbo-blower unit is practically equal to zero and can therefore be considered as negligible.

The embodiment of the invention that is illustrated by Fig. 3 of the drawings diiers, concerning the supercharging of the chambers 61 and 62 vof compressor cylinder 6, from the embodiment illustrated by Fig. l, particularly by the fact that the circuit of the air compressed in the main chamber 61 of the compressor is wholly separate from the circuit of the feed and scavenging air intended for the motor cylinder and which passes through the chamber 62 of the cornpressor cylinder.

In the embodiment oi' Fig. 3, blower I9 feeds air only to the chamber S2 of the compressor from which feed and scavenging air is supplied to the motor cylinder. As for the main chamber 6l of the compressor it is fed from the outlet of a turbine 29 which is driven by compressed air coming from said chamber 61 (after passage through reservoir I6 as shown by the drawing). the air delivered by the turbine 29 being still under a pressure above atmospheric pressure and acting to supercharge the chamber 61. Therefore, this last mentioned air circuit is a closed circuit. The mean pressure in this circuit is regulated by means of a slide valve 30 which connects conduit 3|, interposed between the discharge of turbine 29 and chamber 61, either with a source oi air under pressure such, for instance as a compressed air reservoir 32, or with the atmosphere, in order thus to decrease or to reduce the weight of air present in this circuit.'

In order simultaneously to regulate the power ofthe turbo-blower unit 2I-I8, the right .hand side of.` piston 23 is subjected to the action of the pressure existing in said conduit 3| (as shown by the drawing). f

Slide valve 30 may be operated either manually or automatically, for instance by thev speed governor of turbine 29.

"Of course, the variations of the inlet or discharge pressure of the air compressed respectively in compressor chambers 81 and 62 necessitate a suitable regulation of the return energy of the reciprocating structures of the motorcompressor.

This necessity results fromV the fact that this return energy, the greatest part of which is supplied by pneumatic accumulators 9, serves to produce compression work not only in the motor cylinder but also in compressor chamber 6.

- Inthiembodiment shown by Fig. i, a.; .the

.bers 9.1 and 62 are equalit suiiices to operate .the .control device 34 of pneumatic accumulator .9

either by the inlet pressure of said compressor chambers, or by one of the discharge pressures of said chambers.

On the contrary. in the embodiment shown by Fig. 3, preferably, I operate this control-device of the accumulator in accordance with the value of theinlet or discharge pressure both. in main compressor chamber 61 and in the other compressor chamber l62.

Furthermore, in both cases, the accumulator control device must be controlled in accordance with the value of the mean pressure in accumulator 9 itself.

The return energy ofpneumatic accumulator 9 is varied by increasing or decreasing the weight of air entrapped in said accumulator. In order to obtain'this increase, the accumulator 9 is connected, through the control device in question, with a source of air under pressure, for instance with the reservoir I6 which contains the air compressed in chamber B1, while, in order to obtain a reduction of the weight of the air cushion entrapped in accumulator 9, this accumulator is connected, through said control device, for in stance with the atmosphere.

v For this purpose, in the embodiment illustrated by Fig. 1, I provide control device 34 with a slide valve 35 adapted to occupy different positions such that: Y

v(a) It may keep accumulator 9 closed (posi.- tion of the slide valve shown by Figs. 1 and 3): or

(b) It may connect cushion of air 9, through conduits 35 and 3l with reservoir I6; or again (c) It may connect the same cushion, through conduits 36 and 38, with the atmosphere.

Slide valve 35 is made rigid with two pistons 39 and 40 movable respectively in cylinders 4I and 42.

Piston 39 is subjected to the opposed actions of a spring 43 acting on one side thereof and of the mean pressure existing in accumulator 9, acting on the other side of said piston. The mean pressure in question is transmitted to cylinder 4I through a calibrated conduit `44 extending between said cylinder and conduit 36.

Piston 40 is subjected to the action of the mean pressure existing in casing 1, owing to the provision of a calibrated aperture 45, this mean pressure being substantially equal to the discharge pressure in chamber 62.

Finally, I provide, in conduit 31, a check valve 4B intended to prevent a ow of air from ac'- cumulator 9 toward reservoir I6, when the pressure in this accumulator is, for certain positions of piston 8, higher than the pressure existing in said reservoir IB. I

In this way, I obtain a regulation of thereturn energy supplied by accumulator 9, whereby this energy is automatically varied in accordance with the pressure existing in casing vl and of the mean pressure in accumulator 9.

In order to obtain, in the embodiment shown by Fig. 3, the control of slide valve 35 in accordance not only with the pressure existing in cas" ing and with the mean pressure in accumulator 9, but also with the inlet or discharge pressure in main compression chamber 61, distributing valve 35 is controlled, on the one hand, by meansof a piston 391 subjected, through calibrated conduit 44, to the action of the mean pressure existr ingin'accumulatorsand,on the other hand, by.4

,seneca lthe pressure existing in reservoir i6.

For this purpose, said support te of one of the ends of spring 41 is subjected to the action of a cainv 49 carried by a rod 50 the ends of which are rigid, respectively, with a piston '5i and a, piston 52. The ilrst of these pistons, to wit i, is movable in a cylinder 53 under Athe action oi the pressure existing in reservoir it, while the second pistcn, to wit 52, is movable in a cylinder @d under the action, on the one hand, of the mean pressure existing in casing l (which pressure is transl mitted to cylinder E54 through a calibrated ori tice 55) and, on the other hand, of a spring et."

I will now proceed to describe a third embodh ment ci my invention, shown in Fig. d, in which the compressor part oi the motor-compressor, instead of compressing/f separately the air to be fed to a storage reservoir such as i@ and that to be fed to the motor cylinder of the machine, simultaneously performs both of these compression actions and delivers a single stream of air a portion of 4which is sent to the reservoir while the remainder is fed to the motor cylinder after parinvention, it should be well understood that I do not wish to be limited thereto as there might be changes made in the arrangement, disposition and form vof the parts without departing from the principle of the present invention as comprehended within the scope of the appended claims.

What I claim is:

1. A motor-compressor which comprises. in combination, a motor part including a motor cyl inder and a motor piston freely movable in said motor cylinder, a compressor part including a compressor cylinder and a compressor piston tial expansion, for instance in a receiver such as a turbine.

In this embodiment of the invention, the air from the atmosphere passes4 through a blower 60 which discharges it with a certain pressure into the inlet chamber 6i of compressor cylinder 59, which constitutes the compressor part of the motor-compressor. This compressor cylinder is of the double acting type. This air, after compression in said cylinder, issues therefrom through conduit 62.

A portion of this compressed air is sent to reservoir I6 through a conduit tl branching ofi from conduit G2. The remainder is fed through ed to a turbine 63 which is thus operated by said air so as to supply any desired useful worir. The air in question undergoes in turbine tl but a partial expansion so that when it leaves turbine 63 through conduit S4 it is still at a certain pressure. Accordingly this air can be fed through conduit 64 to the motor cylinder 6l of the motor-compressor, where it acts to scavenge and to supercharge said motor cylinder.

The exhaust gases leaving motor cylinder iii pass throughconduiteb, which leads them to turbine 66 which they operate and from which they escape into the atmosphere. This turbine 66 is mechanically connected with blower t@ which feeds compressed air to compressor cylinder 69, whereby said blower d@ is driven by turbine 66.

It should be noted that, in the embodiment i1- lustrated by Fig. 4, there is a single gaseous circuit, including blower 5t, cylinder da, conduit t2, turbine 63, motor cylinder di, conduit @it and turbine 66, from which the gaseous stream is returned to the atmosphere.

In the embodiment of Fig. d, the means for regulating the air cushion in accumulator cylinder 58 are exactly the same as described with reference to Fig. 3, the same elements being designated by the same reference characters. Cylinder 53 is in communication with reservoir id and cylinder 54 is in communication with the inside of motor cylinder 5l through oriilce 55.

In a general manner, while I have, in the above description, disclosed what I deem to be practical and emcient embodiments of the present movable therein and operatively connected with said motorpiston, pre-compression means operative by said motor piston for feeding air under pressure to said motor cylinder, means for supercharging said compressor part, means for supercharging saidpre-compression means including a blower, a gas-turbine. adapted to be fed by the exhaust gases from said motor cylinder, mechanically connected with said blower for driving it, and means for varying the power of said turbine in response to variations of the pressure of the air compressed by said compressor part, and inversely to saidv variations.

2. A motor-compressor which comprises, in combination, a motor part including `a motor, cylinder and a motor piston freely movable in said motor cylinder, a compressor part including a compressor cylinder and a compressor piston movable therein and operatively connected with said motor piston. pre-compression means operative by said motor piston for feeding air under pressure to said motor cylinder, means for supercharging said compressor part, means for supercharging said pre-compression means including a blower, a gas-turbine, adapted to be fed by the exhaust gases from said motor cylinder, mechanically connected with said blower for driving it, and means for varying the power of said turbine in accordance with one of the 4operating pressures oi said compressor part.

3. A motor-compressor which comprises, in combination, a motor part including a motor cylinder with an exhaust port and a motor piston freely movable in said motor cylinder, a compressor part including a compressor cylinder and a compressor piston movable therein and operatively connected with said motor piston, pre compression means operative by said motor piston for feeding air under pressure. to said motor cylinder, means for supercharging said pre-compression means and said compressor part, the means for supercharging said precompression means including a blower, a gas-turbine, adapted to be fed by the exhaust gases from said motor cylinder, mechanically connected with said blower for driving it, conduit means connecting the exhaust port of said motor cylinder with the intake of said turbine, valve means lfor controlling the cross section of said conduit means, and means responsive to variations of the discharge pressure in said compressor part for operating said valve means.

4. A motor-compressor which comprises, in combination, a motor part including a, motor cylinder with an exhaust port and a motor piston freely movable in said motor cylinder, a compresser part including a compressor cylinder and a compressor piston movable therein and operatively connected with said motor piston, precompression means operative by said motor piston for feeding air under pressure to said motor cylinder, means for supercharging said pre-compression means, the means for supercharging said pre-compression means including a blower, a gas-turbine, adapted to be feci by the exhaust gases from said motor cylinder, lmechanically connected with said blower for driving it, conduit means connecting the exhaust port o! said motor cylinder with the intake of said turbine. valve means for. controlling the cross section of said conduit means, and means responsive to variations of one of the operating pressures of said compressor part for operating said valve means.

5. A motor-compressor which comprises, in combination, a motor part including a motor cylinder with an exhaust port, and a motor piston freely movable in said motor cylinder, a compressor part including a compressor cylinder and a compressor piston movable therein and operatively connected with said motor piston, precompression means operative by said motor pistori-for feeding air under pressure to said motor cylinder, means for supercharging both of said pre-compression means and said compressor part in parallel, said supercharging means including a blower, a gas turbine, adapted to be fed by the exhaust gases from said motor cylinder, mechanically connected with said blower for driving it, conduit means connecting the exhaustport of said motor cylinder with the intake of said turbine, valve means for controlling the cross section of said conduitI means, and means responsive to variations of the discharge pressure in said compressor part for operating said valve means so that said cross section is minimum when said discharge pressure is minimum and increases when said discharge pressure increases.

6. A motor-compressor which comprises, in combination, a motor part including a motor cylinder and motor piston means freely movable in said motor cylinder, a compressor part including a. compressor cylinder and a compressor piston movabletherein and operatively connected with said motor piston means, pre-compression means operative by said motor piston for supplying air under pressure to said motor cylinder, means for supercharging both of said pre-compression means and said compressor part, said supercharging means including a blower, and a gas turbine, adapted to be fed by the exhaust gases from said motor cylinder, mechanically connected with said blower for driving it, a pressure accumulator including a cylinder and a piston movable therein. with a mass of air entrapped therebetween, said last mentioned piston being connected with said motor piston means in positive mechanical manner, a source of gas under pressure, a slide valve for connecting the inside of said accumulator cylinder either with said source or with the atmosphere, means operative bv the mean pressure in said accumulator cylinder for urging said slide valve in the direction corresponding to the connecting of said accumulator with the atmosphere, and means operative by the discharge pressure of said pre-compression means. for urging said slide valve in the direction corresponding to the connecting of said accumulator cylinder with said source of gas under'pressure.

7. A motor-compressor which comprises, in combination, a motor part including a motor cylinder and motor piston means freely movable in said motor cylinder, a compressor part including a compressor cylinder and a compressor piston movable therein and operatively connected with said motor piston means, pre-compression means operative by said motor piston for supply-l ing air under pressure to said motor cylinder, means for supercharging said pre-compression means, said supercharging means including a blower, and a gas turbine, adapted to be fed by the exhaust gases from said motor cylinder, me-

chanically connected with said blower for dri ing it, a pressure accumulator including a cylinder and a. piston movable therein, with a massl of air entrapped therebetween, said last men-l tioned piston beingconnected with said motor piston means in positive mechanical manner.'

means operative on the one handl by the mean pressure in said accumulator cylinder, and on the other hand by the discharge pressure of said pre-compression means for varying the -amount of gas in said pressure accumulator.

8. A motor-compressor which comprises, in,I

combination, a, motor part including a motor cylinder and motor piston means freely movable in said motor cylinder, a, compressor partincluding a. compressor cylinder and a compressor piston movable therein andV operatively connected with said motor piston means, an ar,

" motor piston in positive mechanical manner,

means operative on the one hand by the mean pressure in said accumulator cylinder and on the other hand by the feeding pressure of said motor cylinder for varying the amount of gas in said pressure accumulator.

9. A motor-compressor which comprises, in combination, a motor part including a motor cylinder and a, free piston operating in said cylinder, a compressor part including a compressor cylinder and a compressor piston operating in said compressor cylinder and operatively connected to the motor piston, said two pistons forming a unidirectional unit insofar as the motive stroke is concerned, an arrangement for superfeeding the motor part and the compressor part, such arrangement including a rotating blower and a gas turbine, means for feeding to said turbine at least for certain conditions of operation of the motor-compressor the whole of the exhaust gas of the motor cylinder, means mechanically connecting the turbine with thev blower to drive the latter, a pneumatic energy accumulator acting on said piston unit to assure its return strokes, and means responsive to variations in at least one of two pressures, to wit that of the gas entering the motor cylinder and that of the gas delivered by the compressor cylinder, to vary the quantity of gas in said accumulator.

l0. A motor-compressor which comprises, in combination, a motor part including a motor cylinder and a motor piston freely movable in said motor cylinder, a compressor part including a compressor cylinder and a compressor piston movable therein and operatively connected -with said motor piston, pre-compression means operative by said motor piston for supplying air under -pressure to said motor cylinder, means for supercharging said pre-compression means including a blower. a gas turbine, adapted to be Eli der, mechanically connected with said blowerior driving it, a receiver machine interposed between' the discharge oi said compressor part and the intake thereof, whereby air under pressure .supplied by said compressor part performs a certain it, conduit means connecting the .exhaust vnortv of said motor cylinder with the intake of amount of work in said receiver machine, where it expands. and returns-to said compressor part to -be again compressed, the parts through which said air thus circulates forming a closedvoircuit,

cylinder, a receiver machine interposed between the discharge of said compressor part and the intake thereof, whereby air under pressure supplied by said compressor part performs a certain amount of work in said receiver machine, where it expands, and returns to said compressor part t0 be again compressed, the parts through which said air thus circulates forming a closed circuit, and means for varying the weight of air in this circuit so as correspondingly to modify the mean pressure in said closed circuit, means for supercharging said pre-compression means including a blower, a gas turbine, adapted to be fed by the exhaust gases from said motor cylinder, meohanically connected with said .blower for driving turbine, valve means for controlling the cross section of said conduit means, andlmeans re sponsive to variations of the pressure in said closed circuit of the compressor part for operating said valve means'so that said cross section is minimum when said pressure in the closed circuit is maximum and inversely.

i2. A motor-compressor according to claim il,

further'including a pneumatic energy accumw,

lator operatively connected with a motor piston for producing the return strokes thereof, and means for varying the amount of gas in vsaid accumulatoraccording both to the pressure in said compressor part and the pressure in said precompression means.

RAULA PAIERAS PESCARA.

REFERENCES GITED The following references are of record in the le oi this patent:

UNITED STATES PATENT@ Great Britain June 1.6,.1937

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