US2289163A - Internally finned tube - Google Patents

Description

M 7, 1942. s K A ERSEN 2,289,163

INTERNALLY FINNED TUBE Filed June '7, 1948 Patented July 7, 1942 INTERNALLY FINNED TUBE Sol-en K. Andersen, Racine, Wis., assignor to Young Radiator Company, Racine, Wls., a corporation of Wisconsin I Application June 7, 1940, Serial No. 339,258

2 Claims.

The present invention relates to heat transfer devices and particularly the type used for cooling the lubricating oil of an internal combustion engine with either the jacket fluid or a blast of air, the oil being forced through the tubes and the jacket fluid forced around the outside of the tubes. When a blast of air is used as the cooling medium, the tubes are provided with closely spaced fins in order to increase the heat transfer capacity of the device.

One of the greatest improvements made in the past in heat transfer devices when heating a blast of air or wherein a blast of air is used for the cooling medium was in the supplying of the tubes with closely spaced fins through which the tubes extend. My invention applies the same principle to the insideoi the tubes so as to greatly increase the efiiciency of the device and greatly reduce its size and cost.

In recent years it has been the custom to cool the lubricating oil in internal combustion engines. In some devices for this purpose, an air blast is forced between the finsand tubes for cooling. In other devices of the class, the tubes are surrounded by the jacket fluid as a cooling medium. In stationary internal combustion engines, cold water is frequently used as a cooling medium.

The heat transfer capacity of a finned bundle of tubes or of a bundle of tubes surrounded by water is very good but the heat transfer capacity of oil passing through the tubes is very low as compared to the capacity for transferring the heat to the water or to the air.

My invention relates to means for increasing the heat transfer capacity from the oil to the tube somewhat similar to the method used for increasing the heat transfer capacity from the tube to a blast of air by means of closely spaced fins.

An object of the present invention is to approach or practically balance the heat transfer capacity between the oil and tube with the heat transfer capacity from the tubes to the water or air.

I accomplish the foregoing results by supplying the tubes with internal fins, the fins, however, being placed longitudinally in the tube so as to parallel the flow of oil just as fins are positioned on the outside of the tubes so as to parallel the fiow of air.

I have devised my internal fins whereby they may be bonded to the inside walls of the tubes. Therefore it is thought I have provided the last step in heat transfer devices particularly when used for cooling the lubricating oil or for that matter, when used for cooling or heating any fluid passed through the tubes.

.To these and other useful ends, my invention consists of parts, combinations of parts, or their equivalents, and method of manufacture. as hereinafter set forth and claimed and shown in the accompanying drawing inwhich:

Fig. 1 is a side view of one type of heat transfer device making use of closely spaced fins which are bonded to the exterior of the tubes, the tubes being of the flattened type and equipped with my invention, the bottom header being sectioned so as to illustrate the manner of securing the tubes to the header plate.

Fig. 2 is a fractional rear view of the device illustrated in Figure 1.

Fig. 3 is a section through one of the tubes taken on line 3-3 of Figure 2.

Fig. 4 is a transverse sectional view of a round tube equipped with one form of my invention.

It will be understood that the design illustrated in Figures 1, 2 and 3 is adapted for oil cooling where the pressure of the oil is low. The design shown in Figure 4 is adapted for oil cooling when the pressure of the oil is high.

In Figures 1 and 2, the headers are of a type quite different from headers adapted for high pressure. In these figures, the upper header in its entirety is designated by reference character A and the lower header is designated in its entirety by reference character B.

Header A is provided with an inlet or outlet opening l0. Header B is provided with a similar opening as at H, the latter opening being indicated by dotted lines. The tube plates of headers A and B are adapted to receive the ends of tubes H as illustrated in Figure 1.

Tubes 12 are provided with a multiplicity of closely spaced fins l3, these fins are preferably provided with flanges (not shown) which are bonded to the tubes in the usual manner and the ends of the tubes are bonded to the tube plates in the usual manner.

I provide a longitudinally zig zag shaped internal fin which in its entirety is designated by reference character C. The edges of member C are preferably turned outwardly as at l5. Before member C is placed in the tube, edges C5 are considerable further apart than the internal transverse length of the tube. The external width of member C is about the same as the internal width of the tube. Thus it will be seen that when member C is forced into the tube, the folds of member C will be forced together and the fins.

When assembling external fins to tubes, the

custom is to supply a suitable amount of acid to the exterior of the tube so when the bonding material is molten, it will be fused to the fin flanges. In placing the internal fins in the tubes, I pursue this same method. That is, the interior of the tube is tinned and when the heat is applied for bonding the tube to the outside fins, the inside fins will also be fuse bonded to the tubes. The same process is followed when no external fins are provided.

It will be understood that either the internal fins or the inside of the tube or both may be tinned before the fins are positioned in the tube or any other method may be used for applying the bonding material.

In the design shown in Figure 3, clearly there are eleven points that will be bonded to the tubes. In Figure 4 I illustrate another form of tubes and internal fins wherein the fins in their en- 1 tirety are designated by reference character D and are somewhat similar to member C and adapted to be forced into a round tube 2|. These round tubes may be supplied with exterior fins as in Figure 1 but whether furnished with external fins or not, the inside walls of the tubes and fin contact points may be bonded as already described.

Member D is designed so the apexes 22 and the ends 23 of this member are tightly held against the wallof the tubes. Thus, as illustrated. the fins will be bonded to the tube at seven different points.

In any design the internal fins add many times to the metal contact with the oil.

Material from which members C and D are formed is quite thin therefore the internal area of the tube is not reduced to a material extent but as will be noted, the metal contact with the oil will be multiplied many times.

It will be seen that I have provided a simple means for increasing the surface contact of the oil which means, as will be noted, may be designed so as to increase the metal to oil contact over 500%. In fact, my device practically eliminates the major disadvantages mentioned in the present preamble.

Clearly the headers and tube assembly bear no part of the present invention. Figures 1 and 2 are used merely to illustrate one application of the present invention.

Having thus shown and described my invention, I claim:

1. A device of the class described, comprising a tube having longitudinally positioned internal fins, said fins comprising a single strip folded a number of times longitudinally accordion-like and adapted to form yielding pressure contact between its edges, all of the apexes and the wall of the tube.

2. A device of the class described, comprising a tube having longitudinally positioned internal fins, said fins comprising a single strip folded a number of times longitudinally accordion-like and adapted to form yielding pressure contact between its edges, all of the apexes and the wall of the tube and being bonded thereto.

SOREN K. ANDERSEN.

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