USRE17401E

USRE17401E - Cooling system

Info

Publication number: USRE17401E
Authority: US
Publication date: 1929-08-13

Description

Aug. 13, 1929.

/ A. G. M.- MICHELL COOLING SYSTEM s Sheets-Sheet Original Filed June 29, 1925 3 Shee ts-Sheet A. G. M. MICHELL COOLING SYSTEM Original Filed June 29 1923 Aug. 13, 1929.

Aug. 13, 1929. v Re 17,401

A. g. M. MICHELL COOLING SYSTEM 25 By this sam'e'and before proceeding to specify the Reissued' Aug. 13, j

[UNI ED STATES ,PIATENTO OFF-Ice. t

ANTHONY GEORGE MALDON MICHELL, OF MELBOURNE, VICTORIA, AUSTRALIA, AS- SIGNOB, BY MESNE 'ASSIGNMENTS, TO MICHELLCRANKLESS ENGINES CORPORA- TION, OF NEW YORK, N. Y., CORPORATION OF NEW YORK. v

' co'onme sYs'rErL Original Ito. 1,621,943, dated March 22, 1997, Serial 190.6%,543, filed June 29, 1923, and in Australia Application for reissne filed March 22, 1929. Serial No. 349,214;

July 18, 1922.

- The purpose of the present invention is to securemore efficient cooling by ai r cur:

rents of the cylinders, pistons and other working parts of machines operating with hot working fluids particularly internal combustion engines,'the invention being also series of ducts communicating with the at-' mosphere and the channels between said fins, whereby a plurality of air channels are provided, fed continuouslv'with fresh air, the

feed being created either by .a fan or sue-v p tion from the exhaust pressure of the engine. i

In the suggestions hitherto advanced for carrying out this method of air cooling the essential factors governing the practical application of same have not been stated or enlarged upon with a view to ascertaining an efiicient arrangement of the air channels. invention it is sought to achieve improvements according to this-invention thefundamental considerations in the rational design of an air cooling system Wlll.

0 be stated.

The tenor of the calculations is as follows:

The main data of the problem are: (A) The quantity of heat which must be dissipated per unit time in order to maintain asteady temperature (B) the Earea of surface of the hot body which can be made available for conduction of heat to the air;

the difference of temperature between the hot body and the air; (this difference be ng 40 dependent on the temperature of the air,

and the maximum permissible steady temperature of the cylinder or other hot body) (D) the permissible rate at whichenergy may be expended in moving the cooling air for the purpose of bringing it into contact with the body. (A), (B) and (C)-jointly determine the velocity with which air must be caused to flow over the surface of the body, the rate of conduction of heat being known to vary approximately as the threefourths power of the velocity of' the air. j

current of cooling air. increase of temperature to the initial differchiefly contemplated .This velocity jointly with determines the maximum quantity of "air which can-be clrculated, and the latter quantity jointly with (A) determinesa minimum increaseof temperature which must be given to the The ratio of such ence between the temperatures of the hot body and cooling air determines, from known experimental laws, the ratio'of the transverse dimensions of the air channels to their efi'ectivelength. By effective length of an 'air channel is meant its length in the direction of a stramof air from the place where the stream enters the channel to the lace where it leaves.

The velocity and quantity of air, already assigned, jointly determine the total sectional area of these channels while their number and individual dimensions are settled by practical considerations as to economical processes of workmanship having regard to the materials "to be applied."

In this way, there are for each class of materials limitations to the appropriate transverse dimensions and effective lengths of the air channels. For the best results it is usually desirable that the ratio of the effective length of the channel to its width should be of the order of 20 or 30 and a leading objectof the present invention is to secure such a ratio. without incurring difliculties of construction. In the case of cast iron cylinders of ordinary dimensions andas ordinarily constructed theappropriate channels are of comparatively large transverse dimensions and their effective lengths, deduced by the process outlined above, may be such that each channel ex'tends'throughout the length or circumference of the cylinder. In the, case, however, of cylinders of forged steel or similar materials, such as are in the present design, the formation of such relatively. largeichannels 18 very wasteful and expensive, and

channels of relatively small section beingadopted, the process of calculation above exthe use of channels whose plained requires V efiecti've length is, small in roportion to the length or circm'nference o the cylinder.

leading purpose of the present invenv tion is to provide modes of construction and arrangement of. air-channels suitable for forged cylinders of internal combusion e11- ginesand in accordance with the principles above set forth.

As above stated the ratio of the effective length of such channels to their width or smaller transverse dimensions, is of the order internal combusion engine of the crankless.

" type, described in United States patent spec- 'tant from it.

ification No. 1,409,057, the section being taken on the lines DEF of Fig. 2 or ABC of Fig. 3 and passing through both the axis XX of the engine shaft, and the centre line YY of one of the cylinders;

Fig. 2 is a,cross section of one of the cylinders on the line G, G of Fig.1;

Fig. 3 1s a similar cross section on the line H, H of Fig. 1;

Fig. 4 is a diagrammatic view of air channels; and

Fig. '5 is a relatively enlarged view showing details of one channel.

As shown in Figs. 1, 2 and 3 the cylinder 1, whose centre-line is YY, contains a piston 2, in the form of a thin cylinder closed by the end-piece 3, and diaphragm 4, the latter carrying the slipper-cup 5 and slipper G.

The latter makes contact with the swashplate-or slant 7, fixed on the shaft 42 whose centre-line is XX.

In these features, and in its general.m0de of operation the engine is in accordance with Patent 1,409,057 of above cited. Usually several cylinders are arranged circumferentially around the shaft 42, being all equidis- The cylinder 1, is fitted with exhaust valve 8,-and induction valve 9 the latter being contained in an induction branch 10 connecting with the induction chamber 11, communicating with main induction pipe 12. The actuating mechanism of the-valves, the ignition apparatus and other accessories are not shown, the following description and the drawings being restricted to such matters as are necessary for the clear understanding of the nature of the invention, i. e. the improved means of air cooling.

The walls 13, 14 of the cylinder 1, and its combustion chamber, are formed as shown in Figs. 1 and 5 with relatively thin and is a mantle, comprising a thin shell 16 enclosing the fins, and an external jacket 17, the latter being formed in a number of segments 18 between the jackets 17 to the atmos phere. The jackets and shell may be secured to the cylinder 1, by circumferential screwed bars 20, 21 with saddle-pieces 22 or other suitable means (see Fig. 2).

At the outer end of the cylinder the jacketducts 19,, merge into a common outlet consisting' of a circular cowl or short pipe 23, coaxial with the cylinder 1, and surrounding the central exhaust valve 8. The wall 24 of this pipe is continuous circumferentially being formed as a continuation of the peripheral walls of the jackets 17. The interspaces 18 are closed at their outer. ends by cross walls 25, so that no direct communication exists from the atmosphere into the pipe 23. The ducts 19 on the other hand terminate at the opposite or inner end of the cylinders, being preferably of continuously diminishing radial width in this direc-' tion whereby the velocity of the air past the whole of the slots 18 is maintained more or less uniform.

The exhaust valve 8, has its stem 8 and spring 28 supported in a cage 29, which is preferably integral with the ring 30 which forms the exhaust port, being united thereto by webs 31, and furnished with wings 32, (which may be formed as extensions of the webs) extending radially beyond the ring 30, into the path of thea-ir flow from the ducts 19 and thereby acting as cooling fins for the exhaust valve casing 29. The spring 33 of the induction valve 9 is external to the pipe 23 as shown (see Fig. 1).

In order to. draw an effective current of cooling air through the system of pipe 23, ducts 19,

slots

18 and 18, and channels 15, a fan 35, havingblades 36 may be employed. This fan may be mounted directly on the shaft 42, so as to be rotated thereby, and a shroud ring 37 and diaphragm plate 38 may be provided to enclose the pipes 23 of all the cylinders (arranged, as above indi-.

cated, ina-circumferential series) and thus exclude all means of ingress of air, other than that through the passages above mentioned from the atmosphere to the inlet side of the fan.

The action of the 'fan in. inducing the desired current, of air is assisted by the ejector action of the exhaust gases issuing from the ring 30, into the pipe 23, the action of these parts being similar to those of the exhaust, nozzle and blast pipe of a steam radius of the fan and its axial distance from.

the centre of the machine, a light weight attached to its periphery is relatively Very effective for this purpose, and by this arrangement a large deduction from the weight of the slant otherwise necessary may be made. i

In order to effect cooling of the piston, which as above stated is preferably constructed-as a thin cylinder and consequently incapable ottransmitting heat at a suflicient rate by metallic conduction, it is made fluid tight by welding or otherwise hermetically joining the end piece 3-, and diaphragm 4 to the cylindrical body, and a quantity of a suitable conductive liquid, e. g. mercury is enclosed within it. A plug 41, is provided for introducing this liquid which is thrown from end to end of the hollow piston as the latter reciprocates; The end-piece 3 and diaphragm 4 are respectively made convex and concave on their interior sides, so as to effectively distribute the liquid over the surface of the former and of the cylindrical body of the piston as indicated by the dotted lines in Fig. 1.

The use of mercury in a hollow piston as a cooling agent has been practiced or proposed in connection with cylinders cooled by other methods but the application of such cooling agent has a special appropriateness and function in cooling thehead of a long cylindrical hollow piston of the form de scribed, the heat being thus transferred from the head of the piston to'its cylindrical wall, and thence to the corresponding wall of the cylinder, the latter being air-cooled throughout its length. I claim:

1. In a c linder cooledby circulation of air, multip e channels formed circumferent-ially around the cylinder and having each a plurality of lateral inlets alternating with a corresponding plurality of lateral outlets for the circulating air, each inlet and outlet, slot common to a plurality of channels, the length of each channel between inlet and outlet being many times greater than its smaller transverse dimension.

2. In a cylinder cooled by circulation of air, a plurality of circumferential fins formingbetween them narrow channels, and a cylindricalshell enclosing the latter and m which is formed a plurality of, narrow longitudinal inlet slots alternating with a corresponding plurality of narrow outlet slots, each" slot being common to substantially all the channels.

3. A cylinder to be air-cooled. having a series of narrow circumferential channels formed thereon, longitudinal-air ducts transverse to said channels, and a cylindrical covering shell formed with a series of longitudinal slots making communication between the channels and the air ducts.

.4. In a cylinder cooled by circulation of air, a pijlrality of circumferential fins enclosing tween them a corresponding plurality of narrow circumferential channels, and a cylindrical shell enclosing the latter and in which is-formed a plurality of narrow longitudinal inlet slots and a plurality of narrow longitudinal outlet slots extending across the fins, each of the latter opening laterally into a longitudinal duct conveying the air from such outlet.

5. Means for cooling aplurality of cylinrders grouped circumferentially with parallel axes, consisting of a plurality of mantles enclosing each of the cylinders, and through which the circulated air enters radially to each cylinder from the external atmosphere, and from which it is delivered longitudinally into a common outlet casing.

6. The combination of an engine cylinder, a plurality of circumferential fins forming channels surrounding the cylinders, a hollow jacket for the fins, having a plurality of longitudinal slots for admitting air to said channels, said jacket having longitudinal openings in its inner wall between said slots to admit air to the interionof the jacket from said channels.

7. The combination of an engine cylinder, a plurality of circumferential fins formingchannels surrounding the cylinders, a hollow jacket for the fins having a plurality of longitudinal slots extending across the fins for admitting air 'to said channels, said jacket having longitudinal openingsin its inner wall between said slots to admit air to the interior of the jacket from said channels,

means closing the longitudinal slots at one a plurality of circumferential fins, forming channels surrounding-the cylinders, a hollow jacket for the fins having a lurality of longitudinal slots, each for admitting air to all of said channels,'said jacket having longitudinal openings in its'inn'er, wall between saidslots to admit air-to the interior of the jacketfrom said channels, means closing the ongitudinal slots at one end, and an outlet casing communicating with the interior of the jacket, and means for creating a suction in the casing.

9. The combination with an'engine cylinder of peripheral cooling fins thereon, a holtending across the fins, and chambers cover-' low jacket for said fins open at its discharge end and having longitudinal'entrance slotsand exit slots therein exposing said fins to the interior of said jacket, both slots extending across the fins, and an exhaust fan cooperating with the open end of said jacket.

10. The combination with an. engine cylinder, of peripheral cooling fins thereon, a hollow jacket for said fins and having longitudinal entrance slots extending across the fins to supply air to said fins and alterring inclosing a chamber between said cylinder and fan, an an exhaust valve discharging into sald chamber.

11. The combination with an engine cylinder having closely arranged cooling .fins thereon; of a thin mantle surrounding said fins and provided with parallel longitudinal slots crossing the fins, and a jacket having portions arranged between the slots in the mantles to form inlet slots for air, said'po rtions connected by cross walls, and a fan to exhaust one end of said jacket, whereby air will enter through the. inlet slots into the narrow peripheral channels between said fins and pass only partially around the circumference of the cylinder between the fins, through the slots in the mantle into the interior of the jacket for exhaustby said 'fan in substantially separate currents;

12. The combination with an engine cylinder having closely arranged peripheral cooling fins thereon; of a thin mantle contacting with the edges of the fins and having longitudinal slots therein extending across the fins, a jacket surrounding the mantle having longitudinal slots also exing the slots in the mantle of considerably greater peripheral width than the slots in the mantles.

13. Inan air cooled engine, a cylinder having cooling means thereabout, means dividing said cooling means into a plurality of peripherally separated segmental ortions, and independent means exten ing longitudinally of the cylinder substantially throughout the length thereof for conducting cooling air to said segmental portions.

14. In an air cooled engine, a cylinder having cooling means thereabout, means dividing said cooling means into a plurality of peripherally separated segmental portions, and independent peripherally separated means extending longitudinally of the cylinder for conducting cooling air to said segmental portions.

15. In an air cooled engine, a cylinder having peripheral air cooling fins thereon extending around the cylinder, and a plurality of peripherally spaced means extending longitudinally of the cylinder substantially throughout the length thereof for conducting said fins.

16. In an air cooled engine, a cylinder having. a plurality of circumferential channels formed thereon extending around the cylinder, a plurality of peripherally disposed means having separated portions extending longitudinally of the cylinder substantially throughout the length. thereof for conducting air to said channels, and peripherally disposed means having separated portions for conducting the heated air from said channels. 17. In an air cooled engine, a cylinder having a plurality of circumferential channels formed thereon, a plurality of peripherally disposed means having separated portions for conducting air to said channels, and peripherally disposed means having separated portions alternating in location around the cylinder wall with said first named means for conducting the heated air from said channels.

18. In an air cooled engine, a'cylinder, a

plurality of spaced, substantially parallel cooling fins surrounding the cylinder wall, a plurality of passages extending longitudinally of the cylinder for conducting cooling air to the cylinder wall and fins, and a plurality of passages extending longitudinally of the cylinder for conducting air away from said fins and cylinder wall.-

19. In an air cooled engine, a cylinder, a plurality of spaced, substantially parallel cooling fins surrounding the cylinder wall, a

cooling air to segmental portions of plurality of passages extending longitudi-