US2086228A - Free piston motor compressor - Google Patents

Description

July 6, 1937. H. JNxcKE I 2,086,228

' FREE PIs'roN Mforz coMPREssoR I Filed Feb.- 23;'1935 a sheets-'sheet 1 v orma@ July 6, '1937.

H. JANICKE FREE PISTON MOTOR COMPARESSOR Filed Feb. 25K: 1955 3 r Sheets-"Sheet 2v H. JNICKE FREE PISTON MOTOR COMPRESSOR' July s, 1937.

3 Sheets-Sheet 3 Fig. 3

/n ventor al Patented July 6, 1937 UNITED STATES PATENT OFFICE FREE PISTON MOTOR. COMPRESSOR Hermann Jnicke, Dessau, Germany, as signor to Therese Junkers, Gauting, near Munich, Gerlllaflly 20 Claims.

My invention relates to free piston motor compressors. It is an object of my invention to provide means whereby the output'of compressors of the kind aforesaid can be controlled in a particularly simple and efficient manner.

In my copending- U. S. application Serial No. 710,483 I have disclosed a'method of controlling a free piston motor compressor by varying the length of stroke and the pressures thereof, e. g. the suction or discharge pressure, or a combination of both these pressures. My copcnding U. S. application Serial No. 7,786 discloses the control of a free piston motor compressor by means of a variation of the dead space and the fuel supply in a manner such that the piston stroke always remains approximately constant, independently from the variation of the compressor output, While my copending U. S. application Serial No. 7,788. discloses the regulation of a free ypiston motor compressor by the simultaneous variation of at least two of the variables, which at a predetermined constant stroke of the piston determine the output of the compressor as well as the return energy in such a manner that the portion 25 of the total return energy available for the compression of the motor charge must always remain 'approximately constant.

In free piston motor compressors comprising a combustion chamber and one or more compressor chambers, and one or a plurality of freely reciprocating pistons, it has already been suggested to vary the performance of the compressor by varying the length of stroke of the free pistons. Such variation of 4stroke involves certain drawbacks, as thereby the-control of the motor part of the machine, which' is derived from the movement of the free pistons, is subjected to undesirable variations.

It is an object of my invention to enable the performance of the compressor to be varied within Wide limits at substantially constant stroke.

This is eected according to the present invention by regulating the performance of the compressor by varying the pressures and, at the same time, influencing the supply of fuel to the combustion chamber of the motor in such manfree pistons remains (b) The suction pressure; the j perfxirmancek drops if 4this pressure is lowered, and vice versa; (c) The delivery and suction' pressures may be varied at the same time; they may be varied in opposite senses, in which case the influences ex` erted on the performance by suchvariations of pressure add. Alternatively they may be varied v in the same sense, in which .case the performance varies in conformity with the difference between the influences 0I the pressure` variations. In the case last mentioned the proportion of 'the two pressures may be constant and, if the initial temperature is constant, the inaltemperature of thel compressed gas will also remain constant.

In some cases the problem is to vary the amount of energy taken up or of energy delivered, by additional chambers such as, for instance, pneumatic buffers which store compression energy during one stroke and deliver it during the subsequent stroke, this delivered energy, together with the energy which is released in the compressor proper upon the return stroke, compressing the charge in the combustion chamber. In such" additional chambers the same procedure may be adoptedas in the compressor chambers proper, i. e. a variation of pressures, such as, for instance. the initial pressure of compression, at substantially constant str ke of the free piston or pistons.

The controls to be effected. according to this invention, i. e., the variation of pressures and the variation of the quantity of fuel supplied to the motor per power stroke,4 mayY be' effected either manually orautomatically, or one of them manually, the other automatically. y l

Manual control is adoptd, for instance;r if there arise comparatively few v or slow variationsof the demand for compressed` gas',' "or "`if "the frequire ments as tothe exactitudel of controllare vnot high. With such a control the variations of pressure as well as the variation ofthe fuel'supply may be derived from the same control member (a hand Wheel, a lever, or the like) so that each 40 control operation requires only the actuation of this one member. f

If both controls are effected automatically, they' may be inuenced by the variations of a single source of power,'for instance,4by the pressure in a storage tank arranged in series with the compressor. In that ease both control operations are connected in parallel and are suitably tuned with respect to each other. j

However, it is also possible, to render one control'operation dependent of the other, for instance by regulating the pressure inthe compressor in dependency upon the pressure in a storage tank, while the supply of fuel is regulated in dependency upon the pressure in the operations dependent from distinct conditionsl which are not directly related to one another, for instance, to again vary the pressure in the compressor in dependency upon the pressure in the storage tank, but to regulate the supply of fuel to the motor part in dependency upon the stroke in such manner that this stroke remains substantially constant.

I will now proceed to describe my invention with reference to the drawings affixed to this specification and forming part thereof, in which several embodiments of this invention are illustrated diagrammatically by way of example.

In the drawings Figs. 1, '2, 6 and 8 are axial sections of free piston motor compressors with oppositely reciprocable pistons, each of the last two figures show;- ing one-half of the machine while Figs. 3, 4 and 5 are diagrams showing pressures plotted against stroke for the compressors illustrated in Figs. 1 and 2, and

Fig. 'lis a similar diagram for the pneumatic buffer illustrated in Fig. 6.

In the free piston motor compressors shown in Figs. 1, 2, 6 and 8, l is the casing of the motor andv 2 is the central combustion chamber with a compressor chamber 3 at each end. Ihe free pistons are formed by engine pistons 4 and compressor pistons which are directly connected. In order to warrant absolute synchronism of the opposite reciprocatory movements of the pistons, they are connected 4by suitable mechanism, for instance a rack I5 connected to each piston, the racks meshing at diametrically opposite points with a pinion IB which is Ymounted for rotation in a fixed position on the casing I. The left hand motor piston controls the scavenging ports 6 and the right hand motor piston controls the exhaust ports 'l inthe wall of the motor cylinder. 'I'he residual compressed gas whichrernains over in the dead spaces of the compressor at the end of every power Vstroke expands and forces the free pistons toward each other. When the pressure in 'the compressor cylinders has dropped to suction pressure, fresh gas is drawn in through the suction valves 8 and, at the same time, the charge in the combustion chamber 2 is compressed. Toward the end of the: return str ke liquid fuel is injected into the combustion ch mber 2 through pipe 22 and injection nozzl 23 by means of a fuel pump having a piston 20rand a cylinder 2I, and the mixture is ignited. ,'The fuel pump, which is more fully described in my copending application Serial No. 710,483, is operated by a cam 24 formed on the rack I5, which, when the piston is near the end of its inward stroke, turns a rocker 25 which displaces the pump piston 20 against a spring 26.. The products of combustion in the combustion chamber force the pistons apart, the gas which has been drawn into the compressor cylinders, is compressed and conducted to a. storage tank I3 through delivery valves 9, delivery pipes I9 and delivery main. II. A pipe I4 distributes the compressed .gas to the individual stations where it 1s required. `Aspring-loaded check valve I2 is provided in the main II for holding the compression pressure in the compressor chambers at a predetermined minimum even if the pressure in the reservoir should be lower than the minimum, for instance in consequence of heavy tappings of compressed gas, or when the compres-sor .is

started. 'I'he check valve I2 may consist simply-me. g. in a manner similar to that shown in Fig. l-ofa valve body 4I, 42, which a spring 40 tends to close. The top of this spring abuts against a spring abutment 44, which, however, in contradistinction to the showing of Fig. 1, can not be varied as to its position, but may be pro- ',vided either as the cover of the valve casing itself or as some other part rigidly connected with said casing. In this case the'force of the spring acting upon the valve body is always maintained constant. Since the delivery pressure in the compressor `is solely determined by the force of the spring, the delivery pressure in. the compressor likewise can always be maintained at a predetermined minimum value, i. e. may be constant, as indicated in Fig. 4 of the application, 'according-to which the suction pressure only isf varied, while the delivery pressure, despite the aforesaid variation, has remained constant. On the other hand the check-valve I2 can be arranged for 'a variable force of the spring 40 in such a manner that the delivery pressure of the compressor also is rendered variable. A valve of this kind is described below in greaterdet l with reference to Fig. 1.

' e amount of fuel supplied'to the motor per power stroke is regulated automatically in dependency upon the pressure in the storage tank ,one face of the piston, while the pressure in the tank I3 acts on the other face. 'I'he position of the piston 32 is thus determined by the pressure in the tank I3, and consequently the amount of' fuel delivered at each stroke of the pump is a function of this pressure'.

Figs. 1 and 2 further illustrate means for regulating the compressor performance by a variation of pressures.

As shown in Fig. v1, a valve loaded by a spring 40 and opening toward the storage tank is inserted in the main I I leading to the storage tank. The spindle 4I of the valve has the size of a piston so that the valve seat 42 is relieved of the pressure in the tank, and the delivery pressure of the compressor is determined by the tension of spring 40 exclusively. This spring tension, in the example illustrated, is regulated automatically in dependency upon the pressure in the tank. To this end a wedge member 45 is inserted between the end wall 43 of the valve casing and the spring plate 44 acting like a piston.

The wedge member .is connected to a piston 49 valve spring 40 is increased, the delivery pressure of the compressor rises in proportion and the performance is reduced. Obviously the increase of pressure in the compressor can be much greater than the increase of pressure in the tank I3, and the regulation will therefore be rapid and powerful. A

If it is desired to manuallyregulate the compression pressure, the wedge 45 and the means' for Shifting it are replaced by a threaded spindle which is inserted in the end wall 43 of the valve casing and exerts pressure on the spring plate 44.

Fig. 2 shows means for regulating the performance of the compressor by varying the suction pressure. Here all the suction valves 8 are connected to a suction pipe I in which a throttle valve 50 is mounted to' slide, which is connected to a piston 53 which, through a pipe 54, is acted upon by the pressure in the tankV I3 in such manner that this pressure tends to close the throttle valve, While a spring 55 counteracts the pressure on the piston. The spring is so designed that the throttle valve is closed in proportion as the pressure in the tank I3 rises beyond the normal, and the suction pressure is progressively reduced.

The control of the supply of fuel to the motor may be effected in dependency upon the pressure in thetank, as shown in Fig. .1.

The fuel supply may, however, also be regulated in dependency upon the suction pressure, as shown byway of example in Fig. 2. To this end the pipe 35 leading to the cylinder 33 of the fuel-regulating device, instead of being connected to the tank I3, is connected to the compressor chamber 3,this connection ending at 59 in the vicinity of the end face of the compressor piston 5 when this piston has just started for the compression stroke. Mountedv in the pipe 35 is a closing member having the form of a slide valve 60 formed with a port 6I. This slide is connected to the short arm of a rocker 62, the long arm of which is engaged by a pin 63 on the rack I5, so that the reciprocatory movement of the pistons is transmitted to the slide 6I). The ar-- rangement is such that the port 6I connects the compression chamber 3 to the cylinder 33 only if suction pressure acts on the opening 59, the connection being severed when the compressor piston the pressure at the rear of the compressor piston .Cil

5. In this manner interference of this pressure with the operation of the fuel-regulating device 30-34 is prevented.

Fig. 3 is a diagram illustrating the Way in which the compressor is controlled by an increase of the delivery pressure. A B C D A is the diagram for the normal operation of the compressor.' Compression occurs from the suction pressure p1 tothe delivery pressure pz. If the delivery pressure is raised to p21, the new compressor diagram is 'A Bz C2 D1 A. The suction line D1 A of this new diagram is shorter than the suction line D A of the normal diagram. The quantities of gas drawn in, and consequently also the quantities of gas delivered, vary in the same proportion as these lines.

Fig. 4 is a diagram showing the control by a reduction o f the suction pressure.

the new diagram is A2 Bi C Dz A2.` The performances are proportioned similarly as the line B C (at normal performance) relative to the line B1 C (at reduced suction pressure).

Fig. 5 is the diagram of a compressor in-which i" the performance is regulated by simultaneously varying the delivery and suction pressures in opposite senses. If the performance of the compressor (the normal diagram of which is again A B C D A), shall be reduced, the suction pressure is reduced from p1 to p11, While the` delivery pressure is increased from p2 top-2i. The new diagram is Az B2 C2 D2 A2. The performance is Here again A B C D A is the diagram of normal-operation. If the suction pressure is reduced from p1 to p11,

reduced in the proportion of the products from suction line and suction pressure.

Fig. 6 shows a free piston motor compressor with a pneumatic buffer comprising a cylinder 65 and a piston 66 which absorbs energy during the power stroke of the freelymoving masses, stores this energy in its dead space under the form of compressed gas, and returns it to the freely moving masses A during their return stroke. The amount ofl energy absorbed and delivered by the buffer is regulated, according to this invention, by varying the pressure existing in the buffer space at the beginning of compression.l To this vend the space 61 is connected tothe storage tank tank I3 rises to the higher value pn, the new compression line is U V, and the energy absorbed and delivered by the buffer is raised by an amount corresponding to the area S T V U S.

The buffer, or an additional'compressor or the like,.may also be so arranged that it absorbs' energy upon the return stroke of the freely moving mas's, and delivers such energy upon the power stroke of the same. If the compressor piston is larger than the motor piston, the differential piston area of the two, andthe .space 'I0 (Fig. 1) in which this differential area operates, may constitute the buffer or additional compressor.v The amount of energy absorbed by such buffers or compressor chambers during the return stroke of.

the freely movable masses may also be varied by pressure variation, as illustrated, for instance, in

Fig. 8. The space 'I0 adjoining 'the left hand side of the compressor piston 5 may, for example, be a scavenging pump equipped with suction valves 1I and delivery valves 12. the delivery valves 12 to the scavenging air tank 'M (Fig. 6). A throttle 15 is insertedin this pipe which, in a manner similar to the throttle according to Fig. 2, is influenced vby the pressure in the tank I3 in such manner that its throttling action is increased when ,the pressure rises, and vice versa. f r

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described for obvious modifications will occur to a person skilled in the art.

1. A free 'piston motor compressor comprising in combination, a'motor cylinder and at least one compressor cylinder arranged o-n either s ide thereof, a fre'e piston in each cylinder, comprising a motor piston and a compressor piston arranged on the same' side of the motor cylinder being directly connected with each other, means for varying one of the initial and en d pressures in said compressor cylinders and means for at the same time varying the supply of fuel to sai-d motor cylinder in such manner that the length of the piston stroke remains substantially constant.

2. A free piston motor compressor comprising in combination, a motor cylinder and at least one `compressor cylinder arranged on either side thereof, a free piston in each cylinder, comprising a motor piston and a compressor piston arrangedr on the same side of the motor cylinder being directly connected with each other, means for vary- A pipe I3 extends from inder, a free piston in each of said cylinders, comprising a motor piston and a compressor piston arranged on the same side of the motorcylinder' being directly connected with each other, means for varying one of the initial and end pressures in said compressor and additional compression cylinders, and means for at the same time varying the supply of fuel to said motor cylinder in such mannerv that the length of the piston stroke I .f'emains substantially constant.

4. A free piston motor compressor comprising in combination, a motor cylinder, at least one compressor cylinder arranged 'on either side thereof and at least one additiogal compression cylinder, a free piston in each o f said cylinders, comprising a motor piston and a compressor piston arranged on the same side of t e motor cylinder being directly connected wi` h each other, means for varying both the initial and` end pressures in said compressor and additional compression cylinders, 'and means for ait the same time varying the supply of fuelt vsaid motor cylinder in such manner that the ength of the piston stroke remains substantially constant.

-5. A free piston motor compres'oiL comprising in combination, a motor cylinder, a pluralityof compressor cylinders arranged on either side thereof, a free piston in each of said cylinders, comprising amotor piston and a compressor piston arranged, on the same side of the motor cylinder being directly connected with each other, means for varying one of the initial and Aend pressures in part of said compressor cylinders and means for at the same time varying the sup- .ply of fuel to said motor cylinder in such manner that the length of the piston stroke remains substantially constant. Q

6. A free piston motor compressor comprising in combination, a motor cylinder, a plurality of compressor cylinders arranged on either side thereof, a free piston in each of said cylinders, comprising a motor piston and a compressor pist0n arranged on the same side of the motor cylinder being directly connected with eachother, means for varying both the initial and end pressures ln part of said compressor cylinders and means for at the same time varying the supply of fuel to said motor cylinder` in such manner that the length of the piston stroke remains substantially constant.

7. A free piston motor compressor comprising in combination, a motor cylinder, at least one compressor cylinder arranged on either side thereof, and at least one pneumatic builer cylinder, a free piston'v in each cylinder, comprising a vmotor piston and a compressor .piston `arranged compressor cylinder arranged on either side thereof, and at least one scavenging pump cylinder, a free piston in each-cylinder, comprising a motor pistonand-a compressor piston arranged on the same side of the motor cylinder being directly connected with each other, means for varying one of the initial and end pressures in said compressor cylinders and in said scavenging pump cylinder, and means for at the same time varying the supply of fuel to said motor cylinder in such manner that the length of the piston stroke remains substantially constant.

9. The combination, with the free piston motor compressor of claim 2, of means for keeping the relation between the initial and the end pressures in said compressor cylinders constant.

10. The combination, with the free piston motor compressor of claim 4, of means for keeping the relation between the initial and the end pressures in said compressor cylinders constant.

11. The combination, with the free piston motor compressor of claim 1, of means for regulating the fuel supply to the motor cylinder. in

dependency from one-of the initial and end pressures, subjected to variation, in the compressor cylinders.

12. A free piston motor compressor comprising in combination, a motor cylinder and at least one compressor cylinder arranged on either side thereof, a free piston in each cylinder, compris- 3 ing a motor piston and a compressor piston arranged on the same side of the motor cylinder being directly connected with each \other, means f' sametime varying the supply of fuel t said supply.

motor cylinder in such manner that the length4 of the piston stroke remains substantially constant, and Va. single adjusting member adapted to effect the. variation of one of said pressures and of said fuelsupply.

13. A free piston motor compressor comprising in combination, a motor cylinder and at least one compressor cylinder arranged on either side varying both the initial and end pressures in` said compressor cylinders, means for at the same time varying the supply of fuel to said motor cylinder in such manner that the length of the piston stroke remains substantially constant, and a single adjusting member adapted to effect the Avariation bothv of said 14. A free piston motor compressor comprising in combination, a motor cylinder and at least one compressor cylinder arranged on either side thereof, a free piston in each cylinder, comprising a motorl piston and a compressor piston aron 'the same side of the motor cylinder being directly connected with each other, means for varying one of the initial and end pressures in said compressor cylinders and in said pneumatic buffer cylinder, and means for at the same time varying the supply of fuel to said motor cylinder -`v-in such manner that the length of the piston ranged on the same side of the motor cylinder being directly connected with each other, means for varying one of vthe initial and-end'pressures in said compressor cylinders, means for at the same time varying the supply of fuel to said mo- 4tor cylinder in such manner that the length of the piston lstroke remains substantially constant,

pressures and of said fuel A and a single source of power adapted to move both said members.

15. A free piston motor compressor comprising in combination, a motor cylinder and at least one compressor cylinder arranged on either side thereof, a free piston in each cylinder, comprisin 'g a motor piston and a compressor piston arranged on the same side of the motor cylinder being directly connected with each other, means for varying both 'the initial and end pressures in said-compressor cylinders, means for at the same time varying the supply of fuel to said motor cylinder in such manner that the length of the piston stroke remains substantially constant, and

, a single source of power adapted to move both cylinders, means for varying the cross-sectional said members.

`16. A free piston motor compressor comprising in combination,- a motor cylinder and at least one compressor cylinder arranged on either side thereof, a free piston in each cylinder, comprising a motor piston and a compressor piston arranged on the same side of the motor cylinder being directly connected with each other, a compressed air conduit connected to said compressor cylinders, a valve inserted in said conduit and sub- 'jected to the discharge pressure of said compressor, a spring arranged to counteract the discharge pressure acting on said valve, means for varying the tension of said spring in dependency from'the f pressure prevailing in saidA conduit to the rear of said valve and means for varying .the supply of fuel to said motor cylinder in such manner that the length of the piston ,stroke remains substantially constant.

17. A free piston motor compressor comprisingv in combination, a motor cylinder and at least one compressor cylinder arranged on either side thereof, a free piston in each cylinder, comprising a motor piston and a compressor piston arranged on the same side of the motor cylinder being directly connected with each other, suction valves on said compressor cylinders, a suction conduit communicating with said valves, a pressure con.- duit for the gas compressed in said compressor area of passage of -said suction conduit in dependency from the pressure in said pressure con- -duit and means for varying the supply of fuel to said motor cylinder in such manner that the length of the piston stroke remains substantially constant. 'Y

18. A free piston motor compressor comprising in combination, a motor cylinder, at least one compressor cylinder arranged on either side thereof, and at least one pneumatic bu'er cylinder, a free piston in each of said cylinders, comprising a motor piston and a compressor piston arranged on the same side of the motor cylinder being directly connected .with each other, each buier cylinder being xed in alignment with the corresponding compressor cylinder, a pressure v conduit for the gas compressed in one compressor cylinder, said pressure conduit being connected` to'the corresponding buler cylinder near` the point at which the end face of said buier piston is located 'before compression isstarted, and

means for varying the fuel supply to said motor cylinder in such manner that the length of the piston stroke remains substantially constant.

19. A free piston motor compressor comprising in combination, a motor cylinder, at least one compressor cylinder arranged on either side thereof and an additional compression cylinder.' a free piston in each of said cylinders, comprising a motor piston and a compressor piston arranged on the same side of the motor cylinder being directly connected with each other,`means for varying one of the initial and end pressures in said compressor cylinders, and means for at the same time varying the supply of fuel to said mo- 4tor cylinder in such manner that the length of the piston stroke remains substantially constant.`

20. A free piston motor compressor comprising in combination, a motor cylinder, at least one compressor cylinder arranged von either side thereof and an additional compression cylinder, a free piston in each of said cylinders, comprising a motor piston and a compressorvl pistonarranged on the same sideof the motor cylinder bein-g varying both the initial and end pressures in said compressor cylinders, Aand means for at thesame `time varying the supply of fuel to said motor cylinder in such manner that the length of the piston stroke remains substantially constant.

HERMANN JNICKE,

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