US2212094A - Cowling combination - Google Patents

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Aug.20, 1940. K ADOLPH Y 2,212,094

I COWLING COMBINATION Filed Jan. 16, 1959' f/ofar {x115 I Patented Aug. 20, 1940 PATENT ol-"r cg cownme COMBINATION Karl Adolph, Esslingen-on -the-Ne ckar, -Germany,

asaignor to the firm 1. Eberspacher, Esalingenon-the-Neckar, Germany, a corporation of Germany ' Applicationhnuary 16, 1939, Serial No. 251,164

vIn Germany February 12, 1938 ZGIaims.

This invention relates to air flow governing means for internal combustion engines, more especially for air-cooled motors of airplanes.

It is well-known to arrange for this purpose a cowl surrounding the whole motor in the form of a ring and having a stream-line-profile. The cooling air'entering at the front side of this cowling ring passes the cylinders of the engine and thenescapes through a split provided between the cowling .ring and the body of the airplane behind the motor.

Now I have found that this kind of cowling ring is insufllcient to fulfill the enhanced require-- ments in cooling, especially at low flying speeds, the gradient of pressure between the entrance and discharge being petty and therefore the quantity of cooling air passing through the cowlin ring being too small.

At the outer side of such cowling rings, near the fore-edge, there arises a field of strongly reduced pressure. Therefore one has decided to arrange the air-split no more at the rear end of the cowling ring but to bend the cowling ring onits front side in an arcuate way inwards and to leave in the cowling ring an annular split dls-. charging into the field of reduced pressure.

Thus the cooling-air enters the cowling ring at its front-side and also escapes at the front side through the annular split. Hereby a considerably higher difference of pressure between entrance and discharge of the air is available. Nevertheless also with such a cowling ring the eiflciency is increased only to a moderate -extent, because' the field of reduced pressure is not-always pro- 5 duced at the same point on the outside of the cowling ring but its position and amount depends upon .the conditions of flight prevailing every moment, i. e."it varies with the directon and the speed of the flght and with the number of revolu- 40 tions of the propeller.

The invention relates to air, flow governing -means for internal combustion engines, especially motors of airplanes, comprising an outer streamline cowl annularlyand concentrically encom- 1 5 passing the engine from the outside, and asimilar 65 matic-axial cross-section. The outlines of the ing ring o to form the partition and havingapertures on its periphery to receive the extended portions of the radially disposed cylinder heads of the engine. Between the fore-edge of the outer cowling ring a and the curved part c of the inner cowling ring b an annular split it is left. A further annular cowling ring e isarranged to surround in a certain distance the annular split d. The part c may be shaped in the form of a hollow body or a sheet.

The cooling air entering the inner cowlingring b in the direction of the arrows f first passesLthe motor cylinders and other hotparts to be cooled, then is turned over by a partition I and flows through the annular channel m left free between the cowling rings a and b in the directionof the arrow a forward and toward the discharge split 11. This split leads into the annular channel 11 which is left free between the annular'member e'and the cowling rings a and b and which is passed, in the direction of the arrow h, by the air flowing in from the outside.

-At theopening of the discharge split it always a negative pressure is prevailing owing to the streaming h which pressure retains its place independent of the conditions of the flight. Consequently the cooling air moving in the direction of the arrow-a and passing the cylinder heads of the motor is sucked oil at the discharge split d and carried away by the streaming h at the outside of the outer cowling ring a.

In this way I attain that the split 11 leading off the cooling air does not lie in the direct air current which depending uponthe direction of the arriving flow,'the-number of revolutions of the propeller and the speed of flying produces a field of reduced air pressure at different points. On the contrary, the discharge split d is exempt from these various influences inasmuch as a dislocationofthe reduced pressure practically takes place only outside the member e, whereas the nozzle-shaped channel n between this member e and the cowling rings a and b is not affected by the dislocation of the field of reduced pressure. The conditions of streaming may be varied by displacing the member e in the direction of the arrows i-k, inother words axially whereby the nozzle-shaped cross-section of the annular channel nbetween themember e and the members a another essential structural element,-the control may be effected by a thermostatic device.

I claim: 1. A cowling combination for an air cooled combustion engine, comprisingan outer streamlined cowling ring concentrically encompassing the engine at a predetermined distance and being closed at its rear side'behind the engine, a second streamlined cowling ring arranged within said outer cowling ring and leaving an annular channel between said rings, the inner cowlig ring having apertures on its periphery to receive the extended portions of the radially disposed cylinder heads of the engine and being .bent at its fore-part in an arcuate way toward the fore-edge o! the outer cowling ring, whereby an annular split is left between the bent-over edge of the inner cowling ring and the loreedge of the outer cowling ring, and a third streamlined ring surrounding at a predetermined distance said first and second rings at the por- .tion thereof forming said annular split.

2. In a cowling combination in accordance with claim 1, means for displacing said third streamlined ring in the direction of the axis of the engine.

- KARL ADOLPH.

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