US2121812A - Apparatus for charging constant volume explosion chambers - Google Patents

Description

June 28, 1938. u. MEININGHAUS APPARATUS TOR CHARGING CONSTANT VOLUME EXPLOION CHAMBERS Filed Aug. 5, 1932 ,I 2 Sheetg-Sheet l June 28, 1938.: UQMEININGHAUS APIARATUS FOR CHARGING CONSTANT VOLUME EXPLOSION CHAMBERS Filed Aug. 5, 1932 2 Sheets-Sheet 2 Patented a... 28, 1938 UNITED STATES APPARATUS FOR CHARGING CONSTANT VOLUME EXPLOSION CHAMBERS Y Ulrich Meininghaus,

Mulheim-Ruhr, Germany, I

assignor to Holzwarth Gas Turbine 00., San Francisco, Calif., a corporation of Delaware Application August'5, 1932, Serial No. 627,609 In Germany August '7, 1931 3 Claims.

, My invention relates to apparatus for charging explosion chambers with compressed-air .and

fuel and has for its object to prevent losses occurring with heretofore known apparatus.

5 In explosion chambers such as are used in is highly desirable to complete the charging of the explosion chamber with ignitable mixture at pressures which lie considerably above the atfl mosphere, as thereby the operating process develops with high efficiency. The charge of the so combustion chamber with the operating media as, for example, combustion air, fuel or mixture is effected in such a manner that the operating medium is compressed to the charging pressure outside the explosion chamber and introduced 26 into the explosion chamber under the charging pressure. According to one known method, the operating media compressed to the charging pressure were introduced into the explosion chamber at a moment when the pressure of the 80 combustion gases in the chamber, owing to the expansion of the gases, had fallen to a value which approximately corresponded to the charging pressure. Thus the operating media introduced into 35 drive the residual combustion gases in the chamber in front of them and expel them irom the ,chamber. It was therefore of the essence of this method that the operating media, in particular the whole of the air for combustion, had '40 to be compressed-to the full charging pressure, so that the work of compression was relatively great. In order to reduce this work of compression, according to a. second method, the expansion of the combustion gases was carried to a 46 p essure which lay below the charging pressure; in this case the expulsion-of the residual'combustion gases was no longer effected by combustion air under by air, which may be designated as scavenging 50 air, of a pressure of the residual combustion gases or of a pressure which, in order to overcome the resistance to movement, lay only slightly above the pressure of the residual combustion gases.

When the scavrnging was completed, therefore,

.; the chamber was filled with scavenging air of a the explosion chamber must ing is completed and the full charging pressure, but

pressure approximately equal to the back pressure on the chamber during the scavenging and considerably below the pressure in the chamber at ignition. Upon the introduction of combustion air at the charging pressure, that-is, at a 5 pressure considerably above the scavenging air pressure, expansion of such combustion air occurred at the beginning of the charging phase of the operating cycle the expansion diminishing as the pressure in the chamber was built up to the charging pressure, the high pressure combustion air losing a considerable part of its energy owing to this expansion. The loss of energy takes place owing to the fact that the air assumesa very high velocity, in consequence'of the great pressure drop between the charging pressure-and the pressure of the body of scavenging air in the explosion chamber, such velocity being then retarded in the explosion chamber with the formation of eddies. To this loss of'energy corresponds an expenditure of work which is necessary to drive the high pressure combustionair out of the compression chamber of the compressor into the explosion chamber. This expenditure of work may be expressed briefly by 26 the term expulsion work. v

The present invention thus relates, to a-charging apparatus for constant volume explosion turbines which operates in such manner that after scavenging air of a pressure approximately 30 equal 7 to the back pressure on the explosion chamber has been-introduced into the latter to expel the residual combustion gases therefrom, the chamber is charged during a super-charging step accomplished by such apparatus with combustion-supporting air of still higher pressure with elimination of the above-mentioned expulsion work.

' The problem is solved in accordance with the invention by bringing the chamber space to be 40 charged with operating media, "after the scavengdurin'g compression of the operating medium, into connection with the compression space of a piston compressor for the operatingmedium with the aidof suitable timing and synchronizing mechanisms, so that the pressure of the operating medium during this compression varies in the explosion chamber according to the same law as in the compression chamber of the compressor. 1

A preferred form of my invention will be explained with the aid of the accompanying drawings, in which Fig. 1. represents a diagram in which are plotted as abscissae the various compr.-ssion spaces I of a piston compressor cylinder volumeof 1 cubic meter, and as ordinates the compression pressures resulting in the compressor at a suction pressure. of 1 atm.

Fig. 2 represents a diagram in which are plot- I ted as abscissae the compression ratios and as ordinates the expenditure in work of compression which takes place according to the prior and according to my improved :atpparatus.

Fig. 3 shows a longitudinal section through a constant volume explosion turbine provided with a piston compressor in accordance with the invention i'or compressing the charging air, the working cycles of such compressor being coordimated with those of the explosion chambers.

Fig. 4 isa view in elevation showing the common drive for the compressor, valve controlling distributor andfuel oil pump.

Fig. 5 shows an enlarged section through the throttle nozzles at the discharge end of the compressor, and

Fig. 6 is an enlarged section through one of the fuel pumps and its associated fuel inlet valve.

According to the known method the compression of the combustion air, which generally comes first into consideration as an operating medium because of its large volume, was efiected according to'line I in Fig. 1, so that work of compression to be expended is determined by the diagram area a-b-cd-a. According to the new method the compression line runs according to II and the work of compression is given by the diagram wc--da. It will be seen at once that the expenditure of work in the new method is considerably less than according to the old method; the gain in work corresponds to the area a--bca. The percentage amount of gain can at once be ascertained from Fig. 2, in which curve I corresponds to the work of compression, with single stage compression, according to the old method, and curve II to the work of compression, with single stage compression, according to the new.

What holds good for single stage compression holds good the more so for multistage compression, by which in particular a considerable reduction in the dimensions of'the compressor results, particularly in the second stage, and especially when, as pointed out below the first stage is in the form of a centrifugal compressor. The natural employment of the method developed for the single stage compression for the multistage compression leads to the following modification of the new process. The operating medium is first compressed to an intermediate pressure. After this the operating medium already under the intermediate pressure is compressed from the.

intermediate pressure up to the charging pressure while the explosion chamber space is in communication with the compression space of the compressor compressing from the intermediate pressure to the charging pressure, that is without performing expulsion work. In this process the initial compression of the operating medium which is supplied to the second compression stage already under the intermediate pressure, takes place outside the second stage compressor and combustion chamber, so that work must be expended in expulsion. This expulsion work, however, is not lost since it is regained in the second compression stage.

Figs. 1 and 2 illustrate my improved mode of operation for the case of two-stage compression. According to the known method, the compression in the first stage, i. e. during the compression to the intermediate pressure, was not different from the curve I, so that the working area a,et-Ic'h-d-a corresponds to the expenditure of work in the first stage. The amount of operating medium which is compressed in the first stage and fills of compression in the second stage is thus given by the diagram area fg-ch-f. The new method difiers from the former method in that the chamber space to be charged with operating medium is in communication with the cbmpression chamber of the piston compressor during the corresponding compression of the operating medium. The compression in the first stage therefore runs no longer according to line I, but according to line IV. The compression line of the second stage is given by the line V, which begins at the point k of the intermediate pressure line. Consequently the working area in the first stage is given by the diagram area and in the second stage it is given by the diagram area kch. Consequently the working area a--ei-a corresponds to the gain in work by the new method in the first stage and the working area fg-c--kj to the gain in work by the new method in the second stage. The working areas gained ae1'a and f-g-c kj are hatched for better clearness. In Fig. 2 the corresponding works of compression are illustrated in dependence onthecompression ratio.

The curve I, III corresponds to the work of compression with two-stage compression which must be expended in the old method owing to the expenditure of expulsion work, while the curve IV, V corresponds to the work of compression with two-stage compression when employing the new method. There will be seen at once the considerable advance made by the new method by reducing the expenditure of work for compression at the same compression ratio as compared with the expenditure of work in compression in the old method. This gain is increased to a greater extent as the compression ratios employed become greater, so that a progressive increase in efficiency is to be expected, if it is considered that with the increase of the charging pressure itself an increase in efiiciency is already associated, which remains independent of the gain in work of compression corresponding to the difierencebetween the curves 1 and II or I, III and IV, V.

What has been stated for two-stage compres sion naturally holds good for each multi-stage compression of the operating medium, in particular the combustion air.

A consideration of Fig. 1 shows that the hatched diagram area i-g-c-k-i corresponding to the gain in work in the second stage is considerably greater than the area aei-a corresponding to the gain in work in the first stage.

In a iurtherdevelopment of the inventive idea it is therefore proposed to dispense with the elimination of the expulsion work in the lower compression stages, in particular in the first stage in the case of two stage compression, in order to ob tain in place of this a structurally simpler and more reliable arrangement. Dispensing with this ensures the further advantage that the total compression in the first stage may be done as hither- 'ment for saving expulsion work, and also the advantage that the compressor necessary for the higher compression stages, in particular for the highest stage, turns out'very small and'simple,

so that in this case the gain in work of compression is obtained with particularly simple means. Thus for example for two stage compression, curve VI inFig. 2 represents the total work of compression. which has to be expended when the work of expulsion is eliminated only for the second stage. The curve VI lies very near to the curve IV, V and is still at such a considerable distance from the curve I, III that the employment of the intermediate solution allows the advantages aimed at to be'obtained without an unnecessary excess of operating medium being required in comparison with the operating media which are necessary with the old method.

A particularly simple form of operation with my improved arrangement results if the charging processes of several, preferably all, explosion chambers of an internal combustion engine plant are displaced as regards time in such a manner that there takes place a succession of the charging processes which is effected by a common compressor for these chambers. number of the explosion chambers, the number of their working cycles and the number of the working cycles of the compressor can be timed, so that the number of the working cycles of the compressor is the same as the product of the number of the chambers charged by it and their cycle number. In this case the compressor operates with one cycle of operations to each of the different I chambers alternately in succession.

Thus, for example, 6 explosion chambers having a working cycle number of 100 per minute can be supplied with charging air from one compressor,

if the duration of charging aniount to of the duration of one working cyclepf an explosion chamber and the speed of revolution of the compressor, which is constructed as a piston compressor, is 600 revolutions per minute.

My improved apparatus is characterized by a control of the inlet valves for the compressed operating medium whereby the inlet valves are kept open during the compression'of the operating medium or during a part of this compression, in the case of multi-stage compression preferably during the highest compression stage, or in the case of two stage compression during the second compression stage.

A particularly simple arrangement results if the piston compressor and the chambers of a inlet members of the explosion chambers for the I multi-chamber machine are so arranged that the operating medium, which the compressor supplies in the compressed condition, lie directly. adjacent to the outlet valves of the compressor.

If the inlet valve of each explosion chamber simultaneously forms the controlled outlet valve of the compressor, the apparatus for carrying out the method of the invention is simplified to a particularly great extent.

In the form of the invention shown in Fig. 3, i represents one of the explosion chambers which are arranged with their longitudinal axes on a cylinder surface the axis of which coincides with the shaft axis of the turbine rotor. Each explosion chamber has an outlet valve 2 through which the combustion gases, after ignition and.

explosion, flow to the rotor 3 and impinge thelatter after expansion in the nozzle 4. Through In particular the ing air which is compressed by a centrifugal compressor l6 driven by an electric motor l1 and expels the combustion gases, after expansion of the gases'to the scavenging air pressure has occurred, in'known manner nozzle valve 2. The inlet valve 6 serves for controlling the charging air which is one of, the operating media which have to be delivered to the explosion chamber in a compressed condition. The control of the valve is effected in known manner by way of the oil cylinder 1 actuated by means of pressure oil which is admitted through the oil distributor l5, as described more in detail below.

The inlet valve 6 for the charging air simul taneously forms the controlled outlet valve of a compressor, the piston of which is indicated by 8 and the cylinder by 8. Throttle nozzles H, which are arranged between the compression chamber ll) of the compressor and the interior' l2 oi the valve prevent the combustion gases from striking back from the explosion chamber l into the: compression chamber II! should premature fuel; at the moment when the piston 8 has reached the inner dead point and the inlet valve '6 has closed the fuel injection takes place and immediately thereafter ignition by the spark plug M of the ignitable mixture formed in the chamber. The mechanism for charging the fuel is described more in detail below. During ignition in the chamber I and the expansion oi the combustion gases upon the opening of the nozzle valve 2 as well as during the scavenging oi the explosion chamber by scavenging air enterigig through the valve 5, there takes place one aft r another during equal time intervals the suct on of fresh air by the piston compressor and the charging of the other explosion chambers l iron the same coinpressor 8, 9 one after another. fl'his process presupposes a corresponding displacement as regards time of the working cycles in these chambers.

The described form of construction of the apparatus holds good both for single stage as well as for two-stage compression or according to'the method, in which the expulsion work for the first stage is done, so that it is only eliminated in the second stage. In the arrangement shown in Fig. 3 the piston compressonduring its suction stroke, that is upon movement of the piston 8 from the left to the right, the valve I8 being open and the valve l9 closed, sucks atmospheric air through the valves l3, conduit 28, valve l8 and strainer 2|, so that upon the compression stroke of the piston the whole compression of the air takes place in the piston space H).

In the above-described arrangement the compression takes place in ,a single stage. -A more advantageous operation, however, occurs when the valve I8 is closed and the valve I9 open. In such case the compressor sucks air which has been pre-compressed to the scavenging air pressure by the centrifugal compressor IS, the air passing through valve [9 into the conduit 28. Naturally through the opened when employing the latter/method the output of the turbine with the same'dimensions of the compressor and the explosion chambers is greater by several times. Consequently in carrying out the last method, the compressor receives charging air at the intermediate pressure through the inlet valves l3, which air on further compression during the inward stroke of the compressor flows through the already opened valve 6 under charging pressure into the explosion chamber I. Work of expulsion during thissecond compression stage therefore no longer occurs and the necessary expenditure of work follows the curve VI of Fig. 2 as compared with the expenditure 'of work according to line I, III, which took place when carrying out the known method. The coupling between the piston compressor 8, 9, which is driven by an electric motor 911 (Fig. 4) independently of-the rotation of the turbine rotor 3, the oil distributor l5, the fuel pump 21 and the oil pump 28 is accomplished by means of a vertical shaft 22 which is driven from the shaft 22a of the piston compressor 8, 9 by suitable worm gearing 9b. The rotary movement is trans- 44 is connected through the port 45 with th e oil mitted from the vertical shaft through a bevel gear drive 23 to the horizontal shaft 24 to which the fuel pump 21 andoil pump 28 are coupled. The drive of the rotor 42 of the oil distributor I is effected from this horizontal shaft 24 through the bevel gears 25 and 26 (Fig. 3). Through the common drive of the piston compressor 8, 9, the oil distributor l5 and the fuel pump 27, a uniform working cycle for these devices is automatically obtained. The oil distributor l5 controls the actuating cylinders 1' of the valves 2, 5 and 6 of the individual explosion chambers, according to a selected cycle frequency, through the oil conduits 31, 38 and 39. This actuation proceeds in known manner in such a way that the oil pump 28 feeds pressure oil into the interior of the rotating revolver 42 of the oil distributor, whence it flows, depending upon the position of the revolver 42, in succession into the conduits leading to the different explosion chambers. The annular chambe drain, and at the proper instant in each/cycle discharges the pressure oil from the contr, 1 conduits. If, for example, pressure oil passes hrough the conduit 39 to the piston 46 of the valve 6, the valve 6 is opened against the pressure of the spring 41. When, on the other hand, the oil pressure in conduit 39 is released through connection with the port 45', the spring 41 closes the valve 6 (see Fig. 6)..

Fig. 6 illustrates a section through the fuel pump 21 and'shows the fuel injection device 48 arranged in the valve 6, all on an enlarged scale. The cams 49 are positioned upon the shaft 24 which drives the fuel pump 21, such cams being so displaced circumferentially that they raise the rollers 50 against the pressure of the springs 5| and thereby raisetthe fuel pump pistons 52 in proper sequence. The fuel in the compression space 53 is in this way forced into the conduit 55 through the pressure valve 54 and passes through the port 56 into the hollow spindle 51 of the valve 6. The fuel, under its own pressure, then opens the check valve 58 against the pressure of .the spring 59 and passes through the fine openings 66 in finely divided streams into the explosion chamber, where it becomes intimately mixed with the air charged-by the valve 6. Upon'return of the piston 52 under the pressure of the spring 5|, fuel is sucked into the compression space 53 through the conduit 6| and suction valve 62. The

that the number of piston strokes time bears the relationship of a whole number to the product of the number of chambers by the number of cycles per chamber in the same unit by-pass valve 63 is opened at an instant depending upon the amount of fuel required through suitable adjustment of thelever 64 during the compression stroke of the plunger and so operates in known manner for regulating the amount of fuel fed per cycle.

The fuel pump structure, the fuel valve, the oil distributor and the turbo-compressor shown on the drawings are known perse and are disclosed, respectively, in Oel-und Gasmaschinen" by Heinrich Dubbel (Julius Springer, Berlin, 1926, page 188, Fig. 197), Patent No. 1,786,946 to Hofmann, Patent 'No. 1,763,154 to Holzwarth, and Kolben-und Turbo-Kompressoren by P. Ostertag (Julius Springer, Berlin, 1923, page 252, Fig. 276).

Where in the claims I speak of a piston compressor such term is to be understood to mean a true or pure compressor wherein a charge of gaseous medium is compressed and discharged at every two strokes of the piston, as contradistinguished from a structure of the gasoline engine type in which one or more compression up-strokes alternate with one or more exhaust up-sti'okes, such structure being primarily a power-producing engine and not a continually work-absorbing compressor.

I claim: y

1. The combination of a plurality of constant volume explosion chambers having inlet members for high pressure charging airand for fuel, and outlet members for the high pressure, high temperature explosion gases, said chambers-having also scavenging air valves adapted to charge scavenging air of relatively low pressure into the explosion chamber following the expansion of an exploded charge to expel the residual combustion gases in the chamber, air compressor mechanism including a piston compressor common to said chambers, the outlet of said piston compressor lying in the vicinity of and leading into .the charging air inlet members of said explosion chambers, an inlet in the compressor cylinder for charging air thereinto of a pressure approximately equal to that of the scavenging air charged into the explosion chambers, timing mechanismsaid chambers, the speed of the timing mecha-' nism and that of the compressor 'being so related per unit of of time. v

2. The combination of a plurality of constant volume explosion chambers having inlet members for high pressure charging air and for fuel, and;

outlet members for the high pressure, hightem perature explosion gases, said chambers having also scavenging air valves and conduits leading air of relatively low pressure to such valves, air compressor mechanism including a piston compressor common to said chambers, conduitsleading from the compressor to the charging air inlet valve of each of the chambers, the inlet endsof said chambers and'the outlet end of said compressor lying in the vicinity of each other to'reduce the size of the connections between the compressor and chambers, a conduit for leading air of approximately scavenging air pressure into the compressor, mechanism for driving the compressor at approximately constant speed, timing mechanism for the inlet and outlet members of the explosion chambers synchronized with the movement of the piston compressor and acting to open the scavenging air valves of the chambers in rotation while the corresponding outlet membar is open and subsequently to close the scavenging air valve and the outlet member and open the charging air valve of the chamber being charged to connect the chambers in succession with the piston compressor at approximately the beginning of a compression stroke when the pressures in the connected chamber and compressor are approximately the same, the outlet member of the chamber remaining closed, the speed of the timing mechanism and of the compressor being so related that the number of strokes of the com pressor piston per unit of time bears the relation of a whole number to the product of the number of chambersby the cycle frequency of the chambers for the same unit of time, the compression space of'the compressor being arranged out of the path of the live explosion gases discharging from said chambers.

3. In an explosion turbine plant, the combina- ,tion with the rotor and driven shaft of such plant, of a plurality of constant volume explosion chambers having inlet members for the components of the mixture to be exploded therein and for scavenging air, and outlet members for the high pressure, high temperature explosion gases; a

pressor being connected with such chambers by way of the respective inlet members; a conduit for leading the component to'be compressed into the compressor; mechanism separate from the rotor shaft for driving the compressor at substantially constant speed; and timing mechanism for the inlet and outlet members of the explosion chem-- bers synchronized with the movement of the compressor and constructed to cause opening of the scavenging air inlet member of a chamber following an explosion and the subsequent expansion out of the outlet member, while the corresponding outlet member remains open andthen to close the outlet member substantially simultaneously with the beginning of the compression stroke of the compressor, said compressor having a two-stroke cycle and said timing mecha-.'

nism acting to connect the explosion chambers in alternation with the compression space of the compressor substantially at the beginning of the compression stroke, whereby during the whole of the compression stroke of the compressor the gaseouscomponent is compressed into an explosion chamber and the pressure of such component continuously increases.

ULRICH MEININGHAUS.

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