US1729042A - Aviation motor - Google Patents

Description

Sept. 24, 1929. H. JUNKERS AVIATION MOTOR Filed June 29. 1920 P atented' Sept. 24, 1929 PATENT OFFICE HUGO J'UNKEBS, OF DESS AU, GERMANY AVIATION MOTOR Application filed June 29, 1920, Serial No. 392,838, and in Germany November 11, 1916.

My invention refers to motors and more especially to the motors used in connection with flying machines designed for use at high altitudes. It is a particular object of my invention to provide a motor capable of developing a constant turning Ynoment at all altitudes within a certain range, from sealevel up to the highest altitude attainable by the machine.

When flying machines are designd to work mostly in great altitudes it is necessary to drive them by the aid of motors which retain their full power in these altitudes contrary to normal motors Whose power decreases with increasing altitude.

In the motor according to the present invention the piston or pistons have a somewhat larger diameter than the pistons of a normal motor of equal output designed to work only in air of about one atmosphere absolute pressure that means that for instance the cylinder section oi the new motor is to that of the normal one as the inversion of the density of the atmosphere. at the altitude in which the 535 flying machine is to work is to the density of the air on the'surface of the earth. All other dimensions e. g. those'of the driving gear remain almost identical. Thus the new motor is bound to develop under otherwise equal conditions the same power at a certain altitude as the normalfmotor on the surface of the earth. Inorder'to ensure an unvarying output in the intermediate regions between the earth and the normal working height and to prevent the new motor from being dama ed by overstraining within the regions of higher density of air a regulating appliance must be inserted in the pipe admitting the air for combustion to the motor which prefer- 40 ably automatically reduces the pressure, i. e.

the quantity of the air admitted to the cylinders,to such an extent that the pressure upon the piston cannot exceed a reasonable limit.

The insertion of an automatic regulator 7 offers the important advantage that the throttling or air admission does not depend upon the attention and care of the machinists so that by rapidly and frequently changing the height the motor can neither be imperilled by overstraining through admitting air of can be arranged which is to be inserted in the air admission pipe, influences all cylinders connected with this pipe and is adjusted automatically according to the varying density of air; or the regulating machinery can be arranged so that in influences the time ofthe opening of the suction valves (or slides) of the cylinders or of the charging pump in such a manner that these will be kept open for a lesser percentage of the piston stroke in denser than in thinner air.

In the drawings aflixed to this specification and forming part thereof devices embodying ngy Invention are illustrated diagrammatic lly by way of example.

In the drawings:

Fig. 1 is a longitudinal section of a device for regulating the tension ofthe inlet valve spring in proportion to the altitude,

Fig. 2 discloses diagrammatically by way of example a regulating device for use with the1 motor according to the present invention, an

Fig. 3 discloses a two-stroke cycle engine embodying the principles of my invention.

Referring to ig. 1, 1 :is the air suction pipe leading to the cylinders. A throttling valve 2 is insertei in this pipe which acts under pressure of spring 3, the resistance of thisspring is to be overcome by the admitted air. As the air enters the admission pipe 4 under the pressure of the surrounding air, this pressure after passing valve 2 is reduced according to the tension of spring 3. So the degree of throttling can be adjusted to the varying density of air in different heights by altering the pressure resting on the valve correspondin to the density of air; in the present case thls can be done by shifting the resting plate 5 of spring 3 by an appliance influenced by the outer air pressure so that the pressure resting on the valve decreases with the decreasing outer air pressure. The adjusting appliance consists of a diaphragm body 6 c osed completely, and filled with a gas of some tension which remains practically,the same. The pressure of this gas is balanced by the pressure of the outer air plus a variable force e. g. the tension of spring 7 or the imminent elasticity of the diaphragm. As the density of air lessens, spring 7 is compressed by the surplus pressure of the diaphragm until its tension plus the outer air pressure keeps balance to the pressure inside 15 the diaphragm body. The ensuing movement of the diaphragm end plate is imparted to the resting plate 5 by means of the rod 8;

as spring 3 rests upon this plate the tension of the former lessens. It is equally advisable 2 to evacuate the diaphragm body 6 so as to eliminate the influence of temperature as far as possible. Instead of imparting themovement of the diaphragm end plate immediately sure, some arrangement can be made by means of which the movement of the diaphragm body brings into action some auxil lary gears (so-called servo-motors) which alter'the pressure resting upon the throttling valve or influence the admission valves or slides of the motor.

A certain deficiency of this arrangementconsists in the fact that the admission of fuel is worked by means of a carburetter. From ordinary carburetters, if working in-air of lesser density, difi'erent mixtures are obtained from those working in air of higher density.

Though some carburetters have been designed which are alleged to be free from these de- 40 ficiencies such carburetters are rather complicated as a ruleand need a very careful handling. Besides it is highly probable that it is the low temperature in higher altitudes that prevents a perfect gasification. These deficiencies can be avoided by admitting the fuel not through a carburetter but in measured quantities for each piston stroke;

this can be done for instance by means of a fuel pump working synchronously withthe 0 motor or by positively moved valves to which the fuel is admitted under an even pressure, or byothermeans. Here the quantity of fuel a admitted for every working stroke and every cylinder should not exceed the amount which can be perfectly consumed by the amount of air admitted at great height, preferably the height mostly used for flying (normal altitude).-

A motor thus arranged if compared to a motor fitted with a carburetter has the advantage that the fuel consumed remains exactly the same atall altitudes so that a fairly equal turning moment of the motor is assured from the surface of the earth to normal altitude. As then the fuel'admission does not to the appliance for altering the valve pres-.

depend upon the amount of air admitted and does not exceed the amount needed "by the motor tp develop full power at great height an overstraining of the motor in air of higher density is made impossible without using any as to assure a perfect gasification under the most adverse conditions. If required the dispersion can be further improved .in a well known manner by injecting the fuel by means of highly compressed air.

When the flying machine oversteps the height at which (the air admission not being throttled) the quantity of the fuel injected per stroke is completely used up a surplus of fuel would be injected. In order to save fuel in such cases and to avoid formation of soot, an appliance can be added which, when this height is overstepped, throttles the admission of fuel for every stroke in the same degree as the density of air decreases.

In flying at lesser height, i. e. in air of higher density such a motor will have a surplus admission of air which increases with decreasing height above the surface of the earth. If this surplusair is considered detrimental to a perfect combustion or if the ignition capacity of the mixture should suffer by it, the addition of an appliance is advisable which, within the span between the surface of the earth and normal flying height throttles the admission of combustion air to the motor automatically so far that a good mixture is ensured. For this'purpose the appliances menp altitude and that for throttling the air admission when flying under this height, can be fitted on the same motor. In order to simplify matters one appliance only can beiarranged to cause the movement of the regulator which below normal altitude merely influences the admission of combustion air and above it merely the admission of fuel.

Referring now to Fig. 2 the fuel is admitted by pump 20 which sucks liquid fuel from a tank 21 and transports it through pipe 22 to the ejector nozzle 23 which e. g. may be inserted in the suction pipe 1. The pump is driven by a shaft 30 coupled with the motor. When overstepping the normal altitude the fuel admission is reduced by shifting towards the left the eye joint 31 of a lever 32 set in motion by shaft 30; hereby the useful part of the strokeof piston 25 is reduced which controls the admission opening 26 its edge 24 Within the range of higher density of air the quantity of combustion air admitted into the cylinderswith each stroke is regulated in the same way as described in above by altering the pressure exerted on a valve inserted in the air suction pipe leading to the motor. 1 is this air suction pipe leading to the motor, 2 the throttling valve,"3 the spring pressing upon it whose pressure must be counteracted by the air streaming in from outside 4 the admission branch which the air enters at barometrical pressure. The tension spring3 is altered by shifting the spring resting plate 5.

The diaphragm body 6 which is airtight and exposed to the outer air pressure serves as a combined organstarting the movements of both regulators; this diaphragm is compressed when near the surface of the earth and expands with increasing height. Rigidly tied'to diaphragm 6 isthe body 18 which so takes part in its movements; it has two grooves 15 and 17 following the centre lines 14 and 16 and guiding the arms 11 and 13 of two angular levers; the grooves are partly leading in the direction of the movement of body 18, partly in oblique lines. One of these angular levers (12, 13) in altering the position of eye joint 31 with its arm 12. influences the output of pump 20. Arm 10 of the other angular lever (10, 11) holding the spring rest 5 influences the tension of spring 3 by its movement.

The machinery is shown in the position maintained in working at normal heights; air and fuel admission remain uninfluenced. When the machine ascends further the diaphragm expands further and shifts body 18 to the right. The end of lever 13 sliding in groove 17 is hereby shifted downwards by the obliquity of the groove into the osition marked by dashes; the eye joint 31 of lever 32 moves to the left, the useful part of the pump stroke and by this the fuel admissionare reduced The end of lever 11 slidingin groove 15 moves along the horizontal part of this groove, lever 10, 11 remains in position and spring 5 remains loose so that the air is admitted to'suction pipe 1 without any hindrance.

When on the other hand the working height of the motor is reduced the diaphragm 6 is compressed by the increasing air pressure and body 18 shifts toward the left. Now lever 11 is turned upwards (into the position marked by dot-s and dashes) by sliding inthe oblique part of groove 15; by doing so spring rest 5. is shifted from its normal position and spring 3 is compressed so that the air sucked in by the motor'has.

to overcome the resistance of the s ring.

Arm 13 of the angular lever 12, 13 regu 'ating the fuel admission slides meanwhile in the horizontal part of groove 17, keeps its normal position and so leaves sion uninfluenced.

By meansof the appliance previously described it is possible to regulate either fuel I i I or air admission by a single appliance carrying out or starting the regulating -motion.

thefuel admissented in the drawing, has an admission port I 31 and an outlet 32 arranged as usual. The regulating device described with reference to Fig. 1 is connected to the admission port 31, the same letters of reference being used as in Fig. 1. A suction pump 34 is connected to the outlet 32 by means of a pipe 33, said pump having its piston.35 connected to the crank shaft 37 of the engine by the connecting rod 36 in such manner that at the moment where the engine piston 38 uncovers the outlet 32, the pump plston 35 will exert a sucking -action, thus causing a reduced pressure in the engine cylinder 30 to be pro-' through the regulating device 18, its quantitybeing regulated in the manner above'described, viz being throttled as long as the engine is working in airrof higher density than-corresponds to an output which the transmission gear can take up without getting too heavily strained. The regulation of the fuel supply can be effected either by a carburetor or by a pump, as above described.

I claim: r

-1. Aninternal combustion engine comprising in combination, a cylinder, a piston reciprocable therein, means connected with said piston for converting its rectilinear motion into rotary motion, means for supplying said cylinder with fuel and air, the diameters of said cylinder and piston being such as to allow of developing the full power, which said converting means cantake up continuously, with part of the quantity of air which said cylinder is capable of holding at atmospheric sea-level pressure, means for operating the motor in a two-stroke cycle, means for automatically regulating the composition and quantity of mixture supplied to said cylinder in dependency upon the varying density of the outer air and means for sucking off the gases of combustion fromlsa'id cylinder, so as to create within said cylinder a vacuum corresponding to the throttlingaction of said supplying means.

2. An internal combustion engine comprising in combination a cylinder, a piston reciprocable therein,- means connected with said piston for converting its rectilinear m0;

' automatically said cylinder and piston being such as to allow of developing the full power, which said converting means can take up continuously, with part of the quantity of air which said cylinder is capable of holding at atmospheric sea-level pressure, means for supplying within certain limits of density of the outer air a constant quantity of non-vaporized fuel for each working strokeand means dependent on the density of the outer air for automatically reducing the quantity of fuel in correspondence to a greater decrease of density of the outer air. f t

3. An internal combustion engine comprising in combination, a cylinder, a'piston reciprocable therein, means connected with said piston for converting its rectilinear motion into rotary motion, means for supplying said cylinder with air, the diameters of said cylinder and piston being such as to allow of developing the full power, which said converting means can take up con-.

tinuously, with part of the quantity of air which said cylinder is capable of holding at atmospheric sea-level pressure, means for supplying within certain limits of density of the outer air a constant quantity of nonvaporized fuel for each working stroke, and

means dependent upon the density of the outer air for automatically regulating the quantity of air supplied to said cylinder, so as to automatically reduce the quantity of air supplied to the correct proportion for full combustion.

"4. An internal combustion engine comprisingin combination, a cylinder, a piston reciprocable therein, means connected with said piston for converting its rectilinear motion into rotary motion, means for supplying said cylinder with air, the diameters of said cylinder and piston being such as to allow of developing the full power, which said eonverting means can take up continuously, withpartof the quantity of air which. said cylinder is capable of holding at atmospheric sealevel pressure, means dependent upon the density of the outer air for automatically regulating up to a predetermined minimum density the quantity of air supplied, means for supplying within certain limits of densit-y a constant quantity of non-vaporized fuel for each working stroke and for reducing said quantity in proportion to the quantity of air admitted in every instance, when said minimum density is overstepped, both said fuel and said air reducing means being under the influence of'said regulating means.

In testimony whereof I aflix my signature.

HUGO JUNKERS.

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