US1296555A - Internal-combustion engine. - Google Patents

Description

H. R. RICARDO.

INTERNAL COMBUSTION ENGINE.

APPLICATION FILED AUG. 15, 1917- 1,296,555, Patented Mar. 4, 1919.

2 SHEETS-SHEET H. R. RICARDO.

INTERNAL COMBUSTION ENGINE.

APPLICATION FILED AUG. 15. I91].

1,296,555, Patented'Mar. 4,1919.

2 SHEETS-SHEET 2.

QFMQE.

HARRY RALPH RICARDO, OF LONDON, ENGLAND.

INTERNAL-COMBUSTION ENGINE.

Specification of Letters Patent.

Patented Mar. 4, 1919.

Application filed August 15, 1917. Serial No. 186,275.

To all whom it may concern Be it known that I, HARRY RALPH R1- cumo, subject of the King of England, residing at London, in England, have invented certain new and useful Improvements in Internal-Combustiou Engines, of which the following is a specification.

As the power of an internal combustion engine depends upon its piston speed and the mean effective pressure on the piston, it is obvious that to obtain an increase in power without increasing the size and weight of the engine either the mean effective pressure or the piston speed must be increased. Any increase in the piston speed means of course an increase in the rotative speed of the engine, thus making the inertia forces of the reciprocating parts and the valves and valve gear excessive. Since the inertia forces increase as the square of the speed, it is not well possible to increase the power of a modern internal combustion engine by increasing the iston speed.

Therefore, toaccomp ish the ob ects of the invention, 1 have designed an internal combustion engine in which the power for a given weight of engine has been increased by increasing the mean effective pressure on the piston, at the same time working with a low temperature cycle. This is accomplished by giving the explosive charge an initial compression before entering the explosion chamber of the engine. To avoid high temperatures of the explosive mixture due to this initial compression, a cooling system is interposed between the apparatus employed to initially compress the charge and the explosion chamber, thus rendering practical the method of initially compressing explosive charges which in the' past has not proven satisfactory because of the high temperatures of the charge before ignition.

The invention, therefore, comprises an internal combustion engine provided with means for giving the explosive mixture, or a large proportion thereof, an initial compression, and means for cooling the compressed gases before the same enter the explosion chamber, thus securing the advantages of the increased mean effective pressure on the pistons when the explosion occurs without the disadvantages of too high temperatures. The accompanying drawings illustrate an engine which may be taken as an example of a construction in which the present invention is put into practice the engine in question being more particularly intended for use on aircraft. It is to be understood however that for other purposes the grouping of the cylinders and neral arrangement of the engine may be ot erwise than as here shown and described.

In these drawings,

Figure 1 is a longitudinal sectional elevation of a, group of three cylinders two of such groups being arranged at an angle about one and the same crank shaft.

Fig. 2 is an end elevation of the complete engine part of the cooling device being shown broken away and in transverse section.

Like letters indimte like parts throughout the drawings.

The complete engine comprises two groups each composed of three cylinders A, A and B two of which A and A are high pressure and one a low pressure cylinder B. The cylinders in each group are arranged in line with the pistons C in the high pressure cyllIldBIS connected to similarly set cranks D arranged on a crank shaft D at 180 to the crank D to which is connected the piston E of the low pressure cylinder B. The latter is disposed in the center with a high pressure cylinder A on one side thereof and the other high ressure cylinder A on the other side thereo The two groups of cylinders are relatively inclined at approximately 90 to each other about the-same crank shaft D with the cooling device F conveniently placed between the groups of cylinders and over the crank shaft as shown in Fig. 2.

The piston in each cylinder conveniently comprises one portion which acts purely as a piston and a trunk portion which is of less diameter than the piston part and takes the entire thrust from the connecting rod. This trunk portion reciprocates in a separate cylinder of less diameter than the main cylinder. The face of the piston which acts as a pump is that annular portion which surrounds the trunk. Referring to Fig. 1 of the drawings it will be seen that this construction is carried out in the case of each high pressure piston C by mounting on its face a hollow cylindrical trunk C of less diameter than the piston portion C. The trunk part C carries the connecting rod gudgeon -pin G and reciprocates in a cylinder H provided with a liner H of antifriction metal. The lower or outer face of the piston C has an annular portion C which surrounds the trunk C and acts as a pump in the outer or lower end ofthe main cylinder A the end of this cylinder being closed and thus consti-f tuting a pump chamber A This chamber communicates through ports J controlled by by the pump faces C of the pistons in both high pressure cylinders, the pipe K communicating with both pump chambers A These charges are delivered alternately to the bulbs K of the cylinders A and A This pipe or passage K is of suitable dimensions and disposed outside the cylinder but is not subjected to special cooling as that is not essential. It is generallypreferable on the other hand to allow this portion of the charge to enter the bulb K in a comparatively heated condition thereby assisting vaporization of the fuel. Particularly is this the case if as has been already mentioned the part charge compressed by each high pressure piston is composed of air only into which after it has entered the pocket K fuel is injected through a valve which in such a construction is suitably arranged in the pocket or in the passage leading tovit. In the case of parafiin being used it may be desirable to inject it with the heated air before it reaches the pocket or bulb. When petrol is used the charge of mixture drawn into the pump chamber A is conveniently heated to some extent before it enters the pump end of the cylinder A. This may be efiected by leading this charge through one or more pipes which pass through the cooling device in a manner more partlcularly hereinafter described.

Each low pressure piston E carries on its lower or outer face a cylindrical trunk E which reciprocates in a cylinder L of less diameter than the cylinder B. Thecylinder L is conveniently provided with a liner L of antifriction metal. The connecting rod gudgeon pin G is carried by the trunk E. That annular ortion E of the lower face of the piston 1% which surrounds the trunk E acts as a pump in the lower end of the cylinder which is closed by an annular plate B. The lower portion of the cylinder B thus forms a pump chamber 13 into which the charge of air or weak mixture is drawn past valves disposed in the end of thecylinder, these valves being of the automatic nonreturn type and convenlently composed of chamber B whichvalve is of the automatic metal leaves or fingers. The; ports B controlled by these valves lead from a chamber B which convenientl formed about the cylmder L and prefera ly extends around the cylinder H. Thus the cool air or mixture passes around these cylinders which act as guldes and has a' useful cooling efiect on them. The delivervvalve from the pum type is disposed in the end B of the cylin-fle der but is not shown in the drawing as it is positioned behind parts which there appear. From this valve leads a passage M of ample dlmensions whose other end opens into the chamber F wherein the compressed charge is cooled before it passes to the high pressure cylinders. .The chamber F may be formed and cooled 1n various ways. For example in the construction shown for use on aircraft it is preferably air-cooled and comprises an annular chamber formed of two cylinders F F of different diameters concentrically disposed with end plates closing the annular spaoeF between the cylinders. The latter are constructed of aluminium or other suitable material and provided with radiating ribs F. Suitably disposed in this cooling chamber F so that they traverse its whole length or an appreciable portion of it are pipesN through which ass the charges which are drawn into the hig pressure pump chambers A These pipes N communicate through a pipe J 2 with the chamber J. Thus the gas drawn through the pipes N takes up some of the heat from the compressed charge. of air which fills the interiorF of the cooling chamber F and in this way the as serves to assist in the cooling of the air in this chamber. It will be seen that in the construction shown the cylinder F forming the inner wall of the cooling chamber is not truly cylindrical throughout but is indented so as to allow the necessary clearance for each group of pipes N. Other arrangements or constructions of the cooling chamber may be adopted as found convenient or desirable.

The compressed gas in the cooling chamber F is led thence to the high pressure cylinders A and A through pipes 0 each of which runs to an opening P in the head of a high pressure cylinder, this openingbeing controlled by a valve P. Each opening P is of ample dimensions and the valve as shown may be of the mushroom type and is positively operated or arranged in some convenient manner the closure being effected by a spring 1.

The gases produced by the explosion of trunk so arranged that it can be rapidl opened and is subjected to the least possible; heating effect from these hot gases. Owing to the disposition of the high pressure .cylinders A and A next to the low pressure cylinder B each passage A constitutes little more than the necessary openings respectively in the wall of the combustion chamber of the cylinder A and in the head of the low pressure cylinder B'.

The construction and arrangement of the valve which controls the opening A is preferably as follows :The valve comprises a disk Q provided with a trunk Q whic'h lies and reciprocates in a short cylinder disposed o posite the valve opening B The preferably carries pistonfrings. The valve stem Q passes centrally through a guide sleeve Q and is acted on by a'spring Q tending to close the valve and also by suitable valve gear, not shown in the drawings, by means of which the valve is lifted. A passage in the form of a ipe which passes outside the cylinder leads om the interior of the chamber Q formed at the back of the valve" disk Q into the end of the low pressure cylinder B, this passage being con trolled by 'a cock or adjustable stop valve of suitable type. By this arrangement the valve Q is balanced but the dimensions of the passage leadin to the chamberQ at the back of the va ve are such that variations in pressure in the cylinder B are not instantaneously communicatedto the back of the valve and by manipulation of the cock controlling this passage to the back of the valve the rapidity with which the balance when disturbed is restored can be varied or adjusted to the desired degree.

The valve Q operates in the following manner :When closed the pressure on each side of the valve disk Q is equal but directly the valve is lifted in order to exhaust the products of combustion from the high pressure cylinder A and allow them to pass through the passage A and opening B into the low pressure cylinder B the pressure on the face of the valve Q is considerably in excess of the pressure that exists on the back of the valve in the chamber Q This diiference of pressure results in a tendency to lift the valve Q against the action of the spring Q and assist the valve gear in opening the valve. As the gases enter the low pressure cylinder B the increase of pressure is communicated to the chamber Q with a rapidity which depends on the setting of the cock in the passage leading to this chamber or on the dimensions of the passage but balance-is soon restored so that the valve can be closed again without diificulty at the right moment.

Owing to the piston like structure of the valve Q Q it is possible to arrange that when" lifted it can be withdrawn clear of work the passage A and when thus withdrawn the valve' is masked. by the end of the cylinder B in which it lies and moves and is shielded from the heating effect of the exhaust gases. Thus undue heating of this valve is avoided.

v The opening through which the gases are exhausted from the cylinder B is conveniently situated in the head of that cylinder and closed by a spring-controlled valve S of mushroom type operated by valve gear in some suitable manner. The exhaust passes out through a pipe S.

The operation of the engine may now be described.

It-is to be noted that while the pistons C in the high pressure cylinders A A operate on the four-stroke cycle the piston E in the low 1pressure cylinder B operates on the two-stro e cycle and these cycles are so timed relatively that while the working strokes of the high pressure pistons alternate these working strokes again alterilate with the working strokes of the low pressure piston.

To commence with it may be assumed, as shown in Fig. 1 of the drawings, thatjthe piston E in the low pressure cylinder B is at the end of its instroke while the pistons C in the high pressure cylinders A A are both at the ends of their outstrokes. The

piston in the cylinder A may be assumed to have just completed its working or third stroke while the piston in the cylinder A has just completed its first and chargingor suction stroke. On' the return strokes of these pistons C they each draw in by their annular pump faces C a charge of air or rich combustible mixture, This charge enters the pump chambers A through the ports J having been drawn through the pipes N and J. The exhaust products from the cylinder A are now passing into the cylinder B through the passage A and opening B as the valve Q has been lifted as shown in Fig. 1. These gases continue to expand in the cylinder B and do on the piston E therein. Simultaneously the charge of air or weak combustible mixture which has been drawn in by the annular pump face E of the piston E is compressed in the pump chamber portion B of the cylinder B and passes thence through the pipe M into the cooling chamber F. The charge in the high pressure cylinder A is compressed by the return or second stroke of the piston C in that cylinder.

The pistons in the cylinders A A now commence their outstrokes and the charges drawn in by the pump faces C of the pistons C in both of these cylinders are now compressed and later both enter the pocket K communicating with the combustion chamber of the cylinder A. At the commencement of this first stroke of the piston in cylinder A the inlet valve P is o ened admitting to that cylinder a charge 0 comressed air or weak combustible mixture rom the cooling chamber F. The charge introduced into the pocket K is mainly or entirely prevented from passing thence through the passage K into the combustion chamber of the cylinder A b the entry of the cooled charge from the c amber F, the admission of these charges being suitably timed for this purpose. In the engine here described the charge preferably enters the pocket K toward the end of the first stroke ofqthe piston the entry being automatic when the pressure in the pipe K exceeds the pressure of the charge which has been admitted into the cylinder A through the opening P. The relative times of entry of these charges may vary however as found desirable. If the charge admitted to the pocket K is air only the passage of this air into the c linder at this stage does not so much signlfy but in the case of a rich charge it is desirable to confine this as far as possible to the pocket. The corresponding outstroke or third stroke of the piston C 1n the cylinder A is performed under the 1nfiuence of the expanding gases consequent on the ex losion of the charge in that cylinder. T e corresponding instroke of the piston E in the low pressure cylinder B results in the expulsion-of the products of combustion from one side of that piston the valve S being opened for this purpose. The other side of the piston E is at the same time acting as a pump and drawing a fresh charge of air or weak mixture into the pump end B of the cylinder. Both the openings B are of course closed during this instroke of the piston E by their valve Q. The return or second stroke of the piston C in the cylinder A now commences and during this stroke the charge in that cylinder is compressed while at the same time a further charge of air or rich mixture is drawn in by the annular pump face C of the piston. The exhaust valve Q between the cylinder A and the cylinder B has now been opened and the products of combustion contained in the cylinder A now pass into the cylinder B and act by expansion on the piston E. The latter is now once more compressing the charge of air or weak mixture which has been drawn in by its annular pump face E and this charge in due course passes into the cooling chamber F. The third stroke of the piston C in the cylinder A then commences as the charge therein is fired by the ignition device in the pocket K. The gases in the pocket when ignited pass with great rapidity through the constricted passage K and mingle with the highly compressed charge of air or weak mixture in the cylinder A causing violent ciently high temperature to ignite the fuel as it enters. On the third stroke of the piston C in the cylinder A the charge drawn in by its pump face C is compressed but owing to the pressure which exists in the pocket K due to the combustion of the main charge in the cylinder A the valve K is kept closed and the fresh charge of rich mixture or air cannot pass from the pump chamber A into the pocket K of the cylinder A but is available to enter the pocket of the cylinder Aat the desired moment. During the corresponding outstroke of the piston in the cylinder A, which is the first stroke of this piston, the charge of rich mixture or air compressed by the annular pump face of that piston passes into the pocket of the cylinder A and after a charge of air or weak mixture has been admitted from the coolin chamber F through the main inlet valve into that cylinder. The corresponding return stroke of the piston E in the cylinder B causes the expulsion of the exhaust products from that cylinder while a fresh charge of air or weak mixture is again drawn into this pump chamber 13 in readiness for delivery to the cool ing chamber. -The cycle then recommences. It will thus be noted that the charges of rich mixture or air drawn into the pump ends of the two high pressure cylinders A and A and compressed by the pistons therein are utilized to constitue portions of the main charges in'these cylinders alternately. The reservoir or cooling chamber F into which pass the compressed charges of air or weak mixture from the low pressure cylinder pump chamber B delivers this air or mixture alternately to the cylinders A and A.

It may be noted that it is only about 20% of the whole main charge for a high pressure cylinder which is compressed by the pump faces of the two pistons C, the remain-' ing of this charge being supplied from the cooled chamber F. If the proportioncompressed by the piston C was much greater it would be necessary to cool it also but such cooling in the preferred construction is not required.

The jacketing in the heads of the cylinders is so arranged as to be carried around the cylinders R in which move the balanced valves Q, Q so that efiective cooling of these valves may be obtained.

Further, as already indicated the charges dealt with in the compression chambers A of the high pressure cylinders A and A may be composed of air and delivered to the cooled chamber F where they mingle with the air charges from the .compression chamber B of the low pressure cylinder. This cooled air is supplied to the high pressure cylinders through the inlet ports and the necessary fuel is injected in a liquid state -into the pockets K which in that case are not cooled. The pipes K for conducting gas to the pockets K and the valves K are not then required.

1 A modification of the invention hereinbefore described is resented in a copending application, Serial RIumber 186,413.

What I claim as my invention and desire to secure by Letters Patent is 1. In an internal combustion engine the combination of two cylinders each formed with a pump chamber at one end, a piston in each cylinder, mean for conveying successive gaseous charges from these pump chambers to the combustion chambers of these 0 linders wherein these charges form art 0% the main charge and as such are urther compressed and subsequently ignited, a third cylinder formed with a pump chamber at one end and a working chamber at the other end, a piston in this cylinder, means for conveying gaseous charges from this third cylinder pump chamber to the combustion chambers of the first two cylinders in turn wherein these charges form a considerable part of the main charges and as such are there further compressedand subsequently ignited, and valve-controlled passages between the combustion chambers of the first two cylinders and the corresponding working end of the third cylinder through which passages the products of combustion after partial expansion in the first two cylinders pass in turn into the third cylinder wherein further expansion takes place and the gases perform work on the iston during each outstroke thereof as set orth.

2. A method of operating a compound internal combustion engine including two high pressure cylinders and a low pressure cylinder which comprises separately compressin partial charges for each hi h pressure cy inder in each of said cylin ers, admitting said partial charges to and'further compressing them in the high pressure cylinders alternately, exploding the total compressed charge, and conducting the products of combustion from the high pressure cylinders alternately directly to the low pressure cylinder and thence to the atmosphere.

'3. In an internal combustion engine the combination of two cylinders each formed with a pump chamber at one end, a piston in each cylinder, means for conveying successive gaseous charges from these pump chambers to the combustion chambers of these cylinders wherein these charges form ignited, a third cylinder formed with a pump chamber at one end and a working chamber at the other end, a piston in this 7'0 cylinder, means for conveying gaseous charges from this third cylinder pump chamber to the combustion chambers of the first two cylinders in turn wherein these charges form a considerable part of the main charges and as such are there further compressed and subsequently ignited, means for cooling the gaseous charges after they leave the pump chamber of the third cylinder and before they enter the combustion chambers of the first two cylinders, and valve-controlled passages between the combustion chambers and the first two cylinders and the correspondin third cylinder throug which passages the products of combustion after partial expansion in thefirst two cylinders pass in turn into the third cylinder wherein further expansion takes place and the gases perform work' on the piston during each outstroke thereof as set forth.

4. A method of operating a compound internal combustion engine including twov high pressure cylinders and a low pressure cylinder which comprises separately compressing partial charges for each high pressure cylinder in each of aid cylinders, cooling the partial charge compressed in the low pressure cylinder, admitting said partial charges to and further compressing them in the high pressure cylinders alternately, exploding the total compressed charge, and conducting the products of combustion from the high pressure cylinders alternately directly to the low pressure cylinder and thence to the atmosphere.

5. In an internal combustion engine the combination of two high pressure cylinders each formed with a pump chamber at one end, a differential piston in each high pressure cylinder operative to compress gaseous charges in the pump chamber end of that cylinder, means for conveying successive gaseous charges from these pump chambers to the combustion chambers of the high pressure cylinders wherein these charges form part of the main charges and as such are there further compressed and subsequently ignited, a low pressure cylinder formed wit a pump chamber at one end thereof and a working chamber at the other end, a differential piston in this low pressure cylinder operative to compress gaseous charges in the pump chamber end of this cylinder, means for conveying gaseous charges from the pump chamber of the low pressure cylinder to the combustion chambers of the two high pressure cylinders in turn wherein these charges form a considerable part of the main charges and as such are there further compressed and subsequently ignited, and valve-controlled passages between the combustion chambers of the two'high pressure cylinders and the corresponding Working end of the low pressure cylinder through which passages the products of combustion after partial expansion in the two high pressure cylinders pass in turn into the low pressure cylinder wherein further expansion takes place and the gases perform work on the piston during each outstroke thereof as set forth.

6. In an internal combustion engine the combination of two high pressure cylinders each formed with a pump chamber at one end, a differential piston in each high pressure cylinder operative to compress gaseous charges in the pump chamber end of that cylinder means for conveying the successive gaseous charges from these pump chambers to the combustion chambers of the high pressure cylinders wherein these .charges form part of the main charges and as such are there further compressed and subsequently ignited, a low pressure cylinder formed with a pump chamber at one end thereof and a working chamber at the other end, a differential piston in this low pressure cylinder operative to compress gaseous charges in the pump chamber end of this cylinder, means for conveying the gaseous charges from the pump chamber of the low pressure cylinder to the combustion chambers of the two high pressure cylinders in turn wherein these charges form a considerable part of the main charges and as such are there further compressed and subsequently ignited, means for cooling the gaseous charges when they leave the pump chamber of the low pressure cylinder and before they enter the high pressure cylinders, and

valve-controlled passages between the com-- bustion chambers of the two high pressure cylinders and the corresponding working end of the low pressure cylinder through which passages the products of combustion after partial expansion in the two high pressure cylinders pass in turn into the low pressure cylinder wherein further expansion takes place and the gases perform work on the iston during each outstroke thereof as set orth.

7. In an internal combustion engine the of the mam charges and as such are there further compressed, means for igniting the charges in the pockets, a low pressure cylinder formed with a pump chamber at one end thereof and a working chamber at the other end, a differential piston in thislow pressure cylinder operative to compress gaseous charges in the pump chamber end of this cylinder, means for. conveying gaseous charges from the pump chamber end of the low pressure cylinder to the combustion chambers of the two high pressure cylinders in turn wherein these charges form a considerable part of the main charges and as such are there further compressed, and valve-controlled passages between the combustion chambers of the two high pressure cylinders and the corresponding working end of the low pressure cylinder through which passages the products of combustion after partial expansion in the two high pressure cylinders pass in turn into the low pressure cylinder wherein further expansion takes place and the gases perform work on the piston during each outstroke thereof as set forth.

8. in an internal combustion engine the combmation of two high pressure cylinders each formed with a pump chamber at one end, a difierential piston in each high pressure cylinder operative to compress gaseous charges in the pump chamber end of that cylinder, means for conveying successive gaseous charges from these pump chambers to the combustion chambers of the high ressure cylinders wherein these charges orm part of the maincharges and as such are there further compressed and subsequently ignited, a low pressure cylinder formed with a pump chamber at one end thereof and a working chamber at the other end, a differential piston in this low pressure cylinder operative to compress gaseous charges in the pump chamber end of this cylinder, means for conveying gaseous charges from the pump chamber of the low pressure cylinder to the combustion chambers of the two high pressure cylinders in turn wherein these charges form a considerable part of the main charges and as such are there further compressed and subsequentlyignited, passages between the combustion chambers of the two high pressure cylinders and the corresponding working end of the low pressure cylinder through which passages the products of combustion after partial expansion in the two high pressure cylinders pass in turn into the low pressure cylinder wherein further expansion takes place and the gases perform work on the piston during each outstroke thereof, and a valve in each of these passages such valve being so constructed that when moved to open the passage it will be withdrawn clear of the hot gases passing from one cylinder to another as set forth.

9. In an internal combustion engine the combination of two high pressure cylinders each formed with a pump chamber at one end, a differential piston in each high pres sure cylinder operative to compress gaseous charges in the pump chamber end of that cylinder, means for conveying the successive gaseous charges from these pump chambers to the combustion chambers of the high pressure cylinders wherein these charges form part of the main charges and as such are there further compressed and subsequently ignited, a low pressure cylinder formed with a pump chamber at one end thereof and a working chamber at the other end, a diflerential piston in this low pressure cylinder operative to compress gaseous charges in the pump chamber end of this cylinder, a cooled chamber into which pass the compressed gaseous charges from the pump chamber of the low pressure cylinder, means for conveying gaseous charges from the cooled chamber to the combustion chambers of the two high pressure cylinders in turn wherein these charges form a considerable part of the main 0 arges and as such are there further compressed and subsequently ignited, and valve-controlled passages between the combustion chambers of the two high pressure cylinders and the corresponding working end of the low pressure cylinder through which passages the products of combustion after partial expansion in the two high pressure cylinders pass in turn into the low pressure cylinder wherein further expansion takes place and the gases perform work on the piston during each outstroke thereof as set forth.

10. In an internal combustion engine the combination of two high pressure cylinders euzh formed with a pump chamber at one end, a difierential piston in each high pressure cylinder operative to compress gaseous charges in the pump chamber end of that cylinder, two pockets each of which communicates with and forms part of the combustion space of a high pressure cylinder, means for conveying successive gaseous charges from the pump chambers of the high pressure cylinders to the pockets of these cylinders in which cylinders these charges form part of the main charges and as such are there further compressed, meansfor igniting the charges in the pockets, a low pressure cylinder formed with a pump chamber at one end thereof and a working chamber at the other end, a differential piston in this low pressure cylinder operative to compress gaseous charges in the pump chamber end of this cylinder, a cooled chamber into which pass the compressed gaseous charges from the pump chamber of the low pressure cylinder, means for conveying gaseous charges from the cooled chamber to the combustion chambers of the two high pressure cylinders in turn wherein these charges form a considerable part of the main charges and as such are there further compressed, passages between the combustion chambers of the two high pressure cyl inders and the corresponding working end of the low pressure cylinder through which passages the products of combustion after partial expansion in the two high pressure cyhnders pass in turn into the low pressure cylinder wherein further expansion takes place and the gases perform work on the piston during each outstroke thereof, and a valve in each of these passages such valve being so constructed that when moved to open the passage it will be withdrawn clear of the hot gases passing from one cylinder to another as set forth.

11. In an internal combustion engine the a combination of two high pressure cylinders each formed with a pump chamber. at one end, a difi'erential piston in each high pressure cylinder operative to compress gaseous charges in the pump chamber end of that cylinder, two pockets each of which forms part of the combustion space of a high pressure cylinder with which the pocket commun cates by a passage in which is a constrlction, means for conveying successive charges from the pump chambers of the h gh pressure cylinders to the pockets of these cylinders in which cylinders these charges form part of the 'main charges and as such are there further compressed, means for igiting the charges in the pockets, a

low pressure cylinder formed with a pump chamber at one end thereof and a working chamber at the other end, a diflerential pisconveying gaseous charges from the pump chamber end of the low pressure cylinder to the combustion chambers of the two high pressure cylinders in turn wherein these charges forma considerable part of the main charges and as such are there further compressed, means for cooling the gaseous charges when they leave the pump chamber of the; low pressure cylinder and before they enter the high pressure cylinders, and valve-controlled passages between the combustion chambers of the two high pressure cylinders and the corresponding working end of the low pressure cylinder through which passages the products of combustion after partial expansion 7 in the two high pressure cylinders pass in turn into the low pressure cylinder wherein further expansion takes place and the gases perform work on the iston during each outstroke thereof as set orth. j

12. In an internal combustion engine the combination of two high pressure cylinders each formed with a pump chamber at one end, a difi'erential piston in each high pressure cylinder operative to compress gaseous charges in the pump chamber end of that cylinder, two pockets each of which forms part of the combustion space of a high pressure cylinder with which the pocket communicates by a passage in which is a constriction, means for conveying successive gaseous charges from the pump chambers of the high pressure cylinders to the pockets of these cylinders in which cylinders these charges form part of the main charges and as such are there further compressed, means for igniting the charges in the pockets, a

low pressure cylinder formed with a pump chamber at one end thereof and a working chamber at the, other end, a differential piston in this low pressure cylinder operative to compress gaseous charges in the pump chamber end of this cylinder, a cooled chamber into which pass the compressed gaseous charges from the pump chamber of the low pressure cylinder, means for conveying gaseous charges from the cooled chamber to the combustion chambers of the two high pressure cylinders in turn wherein these charges form a considerable part of the main char es and as such are there further compresse passages between the combustion chambers of the two high pressure cylinders and the corresponding working end of the low pressure cylinder through which passages the products of combustion after partial expansion in the two high pressure cylinders pass in turn into the low pressure cylinder wherein further expansion takes place and'the gases perform work on the plston during each outstroke thereof, and a valve in each of these passages such valve being so constructed that when moved to pen 'the passage it will be withdrawn clear of the hot gases passing from one cylinder to another as set forth. a

13. In an internal combustion engine the combination of two high pressure cylinders each formed with a pump chamber at one;

end, a differential piston in each high pressure cylinder operative to compress gaseous charges in the pump chamber end of that cylinder, means for conveying successive gaseous charges from these pump chambers to the combustion chambers of the high pressure cylinders .wherein these charges form part of the main charges and as such are there further compressed and subsequently ignited, a low pressure cylinder end, a difierential piston in this low pressure cylinder operative to compress gaseous of each high pressure cylinder, means for conveying gaseous charges from the pump chamber of the low pressure cylinder to the valve controlled ports in the heads of the two highpressure cylinders in turn in which cylinders these charges form a considerable part of the main charges and as such are there further compressed and subsequently ignited, and valve controlled passages between the combustion chambers of the two high pressure cylinders and the corresponding working end of the low pressure cylinder through which passages the products of combustion after partial expansion in the two high pressure cylinders pass in turn into the low pressure cylinder wherein further expansion takes place and the gases perform work on the piston during each outstroke thereof as set forth.

'14. In an internal combustion engine the combination of two high pressure cylinders each formed with a pump chamber at one end, a differential piston in each high pressure cylinder operative to compress gaseous charges in the pump chamber end of that cylinder, two pockets each of which communicates with and forms part of the combustion space of a high pressure cylinder,means for conveying successive charges from the pump chambers of the high pressure cylinders to the pockets of these cylinders in.

which cylinders these charges form part of the main charges and as such arethere further compressed, means for igniting the charges in the pockets, a low pressure cylinder formed with a pump chamber at one end thereof and a working chamber atlthe other end, a differential piston in this'low pressure cylinder operative to compress gaseous charges in the pump chamber end of this cylinder, a valve controlled port in the head .of each high pressure cylinder, means for conveying gaseous charges from the pump chamber end of the low pressure cylinder to the valve controlled ports in the heads of the two high pressure cylinders in turn wherein these charges form a considerable part of the main charges and as'such are there further compressed, means for cooling the gaseous charges when they leave the pump chamber of the low pressure cylinder and before they enter the high pressure cylinders, and valve controlled passage between the combustion chambers of the two high pressure cylinders and the working end of the low pressure cylinder through which passages the products of combustion after partial expansion in the two high pressure cylinders pass in turn into the low pressure cylinder wherein further expansion takes place and the gases perform work on the piston'durmg each outstroke thereof as set forth.

Elle? 15. In an internal combustion engine the combination of two high pressure cylinders each formed with a pump chamber at one end, a difl'erential piston in each high pressure cylinder operative to compress gaseous charges in the pump chamber end of that. cylinder, means for conveying successive gaseous charges from these pump chambers to the combustion chambers of thehigh pressure cylinders wherein these charges form part of the main charges and as such are there further compressed and subsequently ignited, a, low pressure cylinder formed with a pump chamber at one end thereof and a working chamber at the other end. a differential piston in this low pressure \"lindcr operative to compress gaseous charges in the pump chamber end of this cylinder, means for conveying gaseous charges from the pump chamber of the low pressure cylinder to the combustion chambers of the two high pressure cylinders in turn wherein these charges form a considerable part of the main charges and as such are there further compressed and subsequently ignited, passages between the comlnistion chambers of the two high pressure cylinders and the correspoi'iding working end of the low pressure cylinder through which passages the products of combustion after partial expansion in the two high pressure cylinders pass in turn into the low pressure cylinder wherein further expansion takes place and the gases perform work on the piston during each outstroke thereof, a balanced valve in each of these passages comprising a trunk piston movable in a cylinder the end of which opens into the passage and into which cylinder the piston can be withdrawn so as to be clear of the passage, and a pipe constituting a by-pass from the low pressure cylinder to the valve cylinder behind the valve as set forth.

' 16. In an internal combustion engine the combination of two high pressure cylinders each formed with a pump chamber at one end, a differential piston in each high pressure cylinder operative to compress gaseous charges in the pump chamber end of that cylinder, two pocket-s each of which communicates with and forms part of the combustion space of a high pressure cylinder, means for conveying successive gaseous charges from the pump chambers of the high pressure cylinders to the pockets of these cylinders in which cylinders these charges form part of the main charges and as such are there further compressed, means for igniting the charges in the pockets, a low pressure cylinder formed with a pump chamber at one end thereof and a working chamber at the other end, a differential piston in this low pressure cylinder operative to compress gaseous charges in the pump chamber end of this cylinder, a cooled chamher into which pass the compressed gaseous charges from the pump chamber of the low pressure cylinder, means for conveying gaseous charges from the cooled chamber to the combustion chambers of the two high pressure cylinders in turn wherein these charges form a considerable part of the main charges and as such are there further compressed, passages between the combustion chambers of the two high pressure cylinders and the corresponding working end of the low pressure cylinder through which passages the products of combustion after partial expansion in the two high pressure cylinders pass in turn into the low pressure cylinder where in further expansion takes place and the gases perform work on the piston during each outstroke thereof, a balanced Valve in each of these passages comprising a trunk piston movable in a cylinder the end of which opens into the passage and into which cylinder the piston can be withdrawn so as to be clear of the passage, and a pipe constituting a by-pass from the low pressure cylinder to the valve cylinder behind the valve as set forth.

17'. In an internal combustion engine the combination of two high pressure cylinders each formed with a pump chamber at one end, a differential piston in each high pressure cylinder operative to compress gaseous charges in the pump chamber end of that cylinder, two pocket-s each of which forms part of the combustion space of a high pressure cylinder with which the pocket communicates by a passage in which is a constriction, means for conveying successive charges from the pump chambers of the high pressure cylinders to the pockets of these cylinders in which cylinders these charges form part of the main charges and as such are there further compressed, means for i gniting the charges in the pockets, a low pressure cylinder formed with a pump chamber at one end thereof and a working chamber at the other end, a differential piston in this low pressure cylinder operative to compress gaseous charges in the pump chamber end of this cylinder, a cooled chamber into which pass the compressed gaseous charges from the pump chamber of the low pressure cylinder, a valve controlled inlet port in the head of each high pressure cylinder, means for conveying gaseous charges from the cooled chamber to the valve controlled ports -in the heads of the two high pressure cylinders in turn in which cylinders these charge form a considerable part of the main charges and as such are there further compressed, passages between the combustion chambers of the two high pressure cylinders and the corresponding working end of the low pressure cylinder through which passages the products of combustion after partial expansion in the two high pressure cylinders pass in turn into the low pressure cylinder wherein further expansion takes place and the gases perform work on the piston during cylinder the piston can be withdrawn so as to be clear of the passage, and a pipe constituting a by-pass from the low pressure cylinder to the valve cylinder behind the valve as set forth.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

HARRY RALPH RICARDO.

Witnesses: E. C. BAsPER,

R. BAGoo'rr.

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