US2303797A - Air-cooled aircraft engine - Google Patents

Description

Deb. 1, 1942. w, sc Lu 2,303,797

AiR-COOLED AIRCRAFT ENGINE Filed March 20, 1940 2 Sheets-Sheet l In venzfor L 12. w. SQHLUPP 2,303,797

AIR-COOLED AIRCRAFT ENGINE Filgd March 20, 1940 2 Sheets-Sheet 2 Age? . r ses rsreisr f sm-coor. v 1:

seems Waldemar Schlugm, Ber Nllmolesces, Emmy;

- vested in the Alim ortry Application March 29, rest, eriei Em soy srii 3, i939 The 333E583? elutioii relates to eircooled oircroft engines the cylinders of which sre'srrsnged in line. More particularly the present invention refers to'the mesmer of guiding the cooling air to be led sloris thecylinders throughthe space enclosed by the engine cooling.

Etherto it has been usual to provide at the iroot side of the engine cowling and in the side idler-cor on admission opening facing the relative air current and discharge ooenmgs ior the cooling eir which is compressed in front of the cylinder row, whereas behind the cylinders are sreeof reduced w' pressure is formed. In

path on its way through the pressure icy/9c Nos see-sci ill? ' are connected by sir channels, the cross of which may be regulated.

In accordance with the iris/critics it is possible to provide one or more discharge hos in the bilge only without subdivision oi the I tlonl space to obtein as, uniform cylinder pros gradient, becsuse'the cooling our current upon the rear cylinders must flow over e l w therefore is subjected to greater losses or p in the accompanying drawings so tions according to the invention are grammatically by was oi example.

this design the pressure gradient. between the pressure srzsce, provided below the cooling and its front oi the cylinders, end the suction space erreuged behind the cylinders is not uniformly The total 1 distributed over all the cylinders. orvssure gradient of theeir applied to an indifrom the rear" cylinders to the'front cylinders. since the degree of cooling depends on, the sniturie or the total pressure gradient of the air cylinder decreases in the direction oi flight engine cording cool e rovers-i lire the pressure districts the cooling of the front cylinders of on engine cyl nders arranged in line is worse them that of the cylinders situated further reerwsrdly.

The reeson for this defective cooling is the nonuniform distribution of the pressure generated in reassure specs In this case the pressure is lowest at the foremost cylinder and increases towards the adjacent cyliriclers, while the pressure is the suctlori space shows a nearly uniform dis selection "schinsl all the cylinders of on engine cylinders crrorrgedin line. v

In order to obtain satisfactory cooling current proportions in connection with star-type engines w opsoing or a channel for withdrawing the trlbutirtg dieters-so cor ticuisr device,

V cooling; in which. reversiog no coo ing air has been provided at the bilge. oi the cowliiog, i. e., in the range of the choose the isterel well thereof, that is at e point where pressure of the flowing outer'eir is very low. According to the invention the low pressure gorevei ing outside of the bilge of the cowling of on. engine with cylinders disposed in line is utilized for improving the pressure'end flowing goroperties or" the cooling air.

.dccordirrg to the invention, therefore, one or more nozzles are provided in the bilge for leading the cooling air current tothe irorrt cylz'nders, Whereas the cooling air current for the rear cylissders is admitted by nozzles providediri the side well or" the cowiing. For obtaining uniformity oi cooling sir current for cllcylinders the sure lice, specs is subdivided end the separate sggcccs some from the front side oi the cowling tosuction space errtes over In the (ii-swings: Figures 1 end 2 show one oi the structions and the corresponding indicating the pressure distrihutios Figures 3 and 4; show s coristr in a. manner knownper so so ing is provided lathe seer discreet in the bilge of the engine resulting from this construction,

Figures 5 and it shots I the suction space of the r troll well between inders of the row together with the pressure dis responding to this por ostroci-iofooi an cosine to d to the bilge oi Figure 7 shows a o cooling,

' Floors s shows r rrc disgrace relstiris tc the corrstzmotiori il is Fig. i, aridv x sii view of the ocetrolleislc shows in Figs. 5 end. i.

oueoirigs En enters l, air current that is compressed due to flight This cooling air is compressed in ironior the cylinders mounted in specs 2 and escapes coo cylinders end the all the other cyl He.- coristrizctioris the cooliog; sir below the engine cooling through on opening i which, as may be seen from Figure inders, whereas behind the line Po the pressure level in the elevated pressure space decreases from the rear cylinders to the front cylinders; the cylinders arranged in the most forward position being particularly influenced by this pressure drop.

This action detrimental to the cooling efiect is obviated according to the present invention by the fact that, as shown in Figure 3, a reversing nozzle 6 is mounted in the bilge f the cowling. This nozzle creates 9. lower pressure level in the suction space 3 (Figure 3), the pressure gradient having its largest value at the cylinder arranged as far in front as possible. As shown in Figures 5 and 6, discharge opening 5 is provided at the rearward portion of the cowling. Well i which 1. In an air cooled internal combustion enginehaving groups of cylinders arranged in line, a

device for the distribution of cooling air to the cylinders comprising a cowling. surrounding said cylinders and provided with an inlet opening at the front portion thereof positioned laterally on ,one side with respect to the longitudinal plane passing through the axes of said cylinders, an air pressure space and an air suction space being formed within said cowling, said air pressure space extending behind said inlet opening parallel to and divided by said cylinders from said eir suction space extending substantially sympreferably vertically arranged is inserted in the cowling in the level of the cylinder arranged farthest iniront. Wall 7 perfectly closes the suction space of the front cylinder or or the front cylinders with regard to that of the other cylinders. Thus, a pressure level according to line P5, of Figure 6 is obtained the curve of which merges into the line Pe if partial division of the spaces from each other is effected by separator well i providedwith discharge openings 9 the cross sections of which may eventually be altered.

The cross section of openings 9 in separator well i may be made smaller or larger by means of hinged control flaps iii shown particularly in Fig. 9. Flaps It are connected with rods it which in turn are connected with rods l2. Rods id have pins which slide in slots is of plate it.

metrical to said air pressure space, the width of said air suction space increasing from the front end to the rear end thereof, said cowling further comprising an air discharge opening provided in the front portion thereof and arranged on the other side of said longitudinal plane in a.

tion thereof positioned laterally on one side with respect to the longitudinalplane passing through the axes of said cylindersan air pressure space i vhen plate id is moved up from its position sbewn in Fig. 9, rods i2 are turned outwardly in opposite directions and move flaps it into the position shown in dotted lines. Plate is may be actuated by any suitable means,

Ii the curve shown in Figure 6 is compared with the curve of Figure 2, it will be seen that the provision of separator well i results in a sudden reduction of the level of the reduced pressure in suction space 8 adjacent reversing nozzle and coordinated to the foremost cylinders which in turn ceuses a corresponding increase of the total pressure gradient relating to these cylinders.

The curve shown in Figure tiaily altered if, as shown in Figure 7, the engine cowling, setting asidethe air discharge at the reversing nozzle t, is closed against the outer air flow and ii the hitherto usual air discharge openbugs are totwly omitted. This is due to the fact the cooling air through the suction space (see Figure 8). In Fig. 8, D designates the total pressure difference between the elevated pressure space and the suction space, while cpindisates the pressure diflerences within the suction space,

As the cross sections of the openings or nozzles in the separator wall may be regulated as shown particularly in Fig. 9, the total pressure gradient of the iront cylinders of the row may be so inpressed that the cooling of these cylinders is increased and the cooling of all cylinders of the engine is made uniform as far as possible.

Finally according. to the invention the well portion. of reversing nozzle 6 facing the interior 4 is not slibstanand arranged on .dinal plane in end an air suction space being formed within said cowling, said air pressure space extending behind said inlet opening-parallel to and divided by said cylinders from said suction space extending substantially symmetrical to said air. pressure space, said cowling being shaped to provide for e width of said air suction space increasing from the front end to the'rear end thereof, seid cowling further comprising an air discharge opening provided in the trout portion thereof the other side oi said longitua region where the outer air pressure is reduced, 2. wall having openings for controlling the flow or cooling air therethrough and being providedbetween theiront cylinders. of each row of cylinders, and air discharge openings provided at the rear end of said cowling.

3. In an air cooled internal combustion engine with cylinders arranged in line, a device for the that a portion of the total pressure gradient SP oi the rear cylinders is consumedby the flow of tion thereof positioned laterally distribution oi cooling air to the cylinders comprising a cowling surrounding said cylinders and provided with aninlet opening at a 1 one side with respect to the longitudinal plan passing through the axes of said cylindersan air pressure space and an air suction space being formed within said cowling, said air pressure specs extending behind said inlet opening parallel to and divided by said cylinders from said air suction space extending substantially symmetrical to said air pressure space, said cowling tapering towards the front end to provide for a width of said air suction space increasing from the front end to the rear end thereof, a wall having openings for controlling the flow of cooling air therethrough and being provided between the front cylinders of each row of cylinders, said cowling further cornprising an air discharge opening provided in the front portion thereof and arranged on the other side of said longitudinal plane in a region where the outer air pressure is reduced, the rear endoi seid cow being closed, whereby the air in the front por said air suction space flows in a direction opposite to the one of said air pressure space and dis charges through said air discharge opening.

4. In an air cooled internal combustion engine having groups of cylinders arranged in line, a 5

one side with respect to the longitudinal plane passing through the axes of said cylinders, an air pressure space and an air suction space being formed within said cowling, said air pressure space extending behind said inlet opening parallel to and divided by -said cylinders from said air suction space extending substantially symmetrical to said air pressure space, the width of said air suction space increasing from the front end to the rear end thereof, said cowling further comprising an air discharge opening, provided in the front portion thereof and arranged on the other side of said lon itudinal Diane in a region where the outer air pressure is reduced, a wall having controllable openings being provided behind the front cylinders of each group of 'cyling ders for subdividing said air suction space. Y 5. In an air cooled internal combustion engine with cylinders arranged in line, a device for the I distribution of cooling air to the cylinders comprising a cowling surrounding said cylinders and 3 provided with an inlet opening at the front portion thereof positioned laterally on one side with respect to the longitudinal plane passing through the axes of said cylinders, an air pressure space and an air suction space being formed within said cowling, said air pressure space extending behind said inlet opening parallel to and divided by said cylinders from said air suction space ex-:

tending substantially symmetrical to said air pressure space, said cowling being shaped to provide for a width of said air suction space increasing from the front end to the rear end thereof, said cowling further comprising an air discharge opening provided in the front portion thereof and arranged on the other sideiof said longitudinal plane in a region where the outer air pressure is reduced,'a wall having controllable openings being provided behind the front cylinders of each row of cylinders for subdividing said air suction space, and air discharge openings provided at the rear end of said cowling.

6. In an air cooled internal combustion engine with cylinders arranged in line, a device. for the distribution of cooling air to the cylinders comprising a cowling surrounding said'cylinders and provided with an inlet opening 'at the front portion thereof positioned laterally on one side with respect to the longitudinal plane passing through the axes of said cylinders, an air pressure space and an air suction space being formed within said cowling, said air pressure space extending behind said inlet opening parallel to and divided by said cylinders from said air suction space extending substantially symmetrical to said air pressure space, said cowling tapering towards the front end to provide for a width of said air suction space increasing from the front end to the rear end thereof, a wall having controllable openings being provided behind the front cylinders of each row of cylinders for subdividing said air suction space, said cowling further comprising an air discharge opening provided in the front portion thereof and arranged on the other side of said longitudinal plane in a region where the outer air pressure is reduced, the rear end of said cowling being closed, whereby the air in saidair suction space flows in a direction opposite to the one of said air pressure space and discharges thro h said air discharge opening.

-. WALD

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