GB2095813A

GB2095813A - Engine cooler

Info

Publication number: GB2095813A
Application number: GB8201293A
Authority: GB
Original assignee: Hutogepgyar
Current assignee: Hutogepgyar
Priority date: 1981-02-05
Filing date: 1982-01-18
Publication date: 1982-10-06
Also published as: FR2499232B1; HU184377B; DE3147027A1; ATA510081A; GB2095813B; FR2499232A1; DE3147027C2; AT395747B

Abstract

The invention relates to oil or water coolers of the finned-tube type suitable for stationary or motor vehicle engines. Multi-purpose elementary pairs of fins (3) bent-up at 90 DEG are arranged on the lamellae (2) of the engine cooler, which fins (3) partly ensure turbulence of the air flow, and partly they participate in heat dissipation, functioning as heat dissipating surface. A convenient number of two or more pairs of fins (3) are arranged close to the heat transfer pipes (1) symmetrically in the space between adjacent pipes, and the fins (3) also serve to space adjacent lamellae (2). <IMAGE>

Description

SPECIFICATION Engine cooler The invention relates to an oil or water cooler suitable for stationary or motor vehicle engines, where multi-purpose elementary pairs of fins are arranged on heat dissipating lamellae fixed to fluid-carrying pipes of rectangular or elliptic crosssection.

The water coolers are well-known in the field of motor vehicles, in which closely-spaced plates, lamellae are arranged on so-called flat pipes of rectangular or elliptical cross-section. However, the less visible structural details of the cooler in question and the aspects according to which such mechanism is formed are less known.

Formation of the coolers requires heat dissipation, or heat transfer conforming to as high motor performance as possible, at the minimum dimensions. Thus the coolers require heat dissipation related to a iarge volume unit. In many cases, however, especially for up-to-date, fast motor vehicle engines, air is available only at the velocity corresponding to the running speed, since the cooling fan is operative only at low speeds, or in a stationary position. In this case the air resistance of the cooler is an even more essential aspect.

Based on the optimum calculation of the coolers it was found that the thinner the material of the lamellae, the higher is the heat dissipation per unit volume. In this field, however, the development reached the technical minimum since thinning of the fins is limited by the strength. For this reason other means had to be found to increase the efficiency.

It is well-known that turbulence of the air resistance increases the heat transfer properties, consequently various turbulence-forming structures are used. Such structures, however, will increase the flow resistance of the finned tube as well. Thus the optimal ratio has to be found for the plain and turbulence-forming lamella sections.

Construction of the coolers requires furthermore the gaps between the lamellae to be uniform, since uniform fin distribution is primarily not an aesthetic question, but absolutely necessary for the uniform air flow. Spacer lugs are generally used to ensure uniform fin distribution, but these do not participate in the heat dissipation and their adverse or advantageous effect on the flow is disregarded in their design. They are generally arranged along the centreline between two pipes, where the fin is the coldest, thus the heat dissipation is minimal.

Finally the local flow picture has to be taken into consideration for construction of the cooling mechanism, the less utilized areas behind the pipes and turbulence-forming structures have to be arranged where most suitable.

On the basis of above recognition the engine cooling mechanism according to the invention ensures heat dissipation for large unit volume at the expense of relatively low resistance-increase by rational and optimal formation of the lamellae.

The essence of the invention is that multipurpose elementary pairs of fin bent up at 900 are arranged on the lamellae of the engine cooler, which partly ensure turbulence for the air flow and partly participate in the heat dissipation, functioning as heat dissipating surface, since a convenent number of two or more pairs of fin are arranged close to the heat transfer pipes symmetrically to the centre-line of the field surrounded by two flat pipes, finally they ensure the distance between the lamellae.

The optimal number of elementary pairs of fins according to the invention is given by thermodynamic and technological considerations in such a way that the ratio of the plain, i.e. finned sections, s and finless, i.e. interrupted, sections m is equal to or higher than one. That is:

As a result of their turbulence-forming function and for the purpose of deflecting the air flow, the elementary pairs of fins may be curved in such a way that the elementary pair of fins bent up at 900 and mainly parallel with the direction of the air flow are curved and the tangent drawn to the curves is at an angle of 0--1 5 0 to the airflow.

The elementary pairs of fins according to the invention may be used behind each other in a solcalled straight and also in a staggered arrangement applicable for engine coolers with displaced pipe arrangement as well.

The invention is described in detail and by way of example with the aid of the accompanying drawings, in which: Figure 1 is a front view of the conventional laminar engine cooler, Figure 2 is a top view of the laminae of the engine cooler with displaced pipe arrangement according to the invention, Figure 3 is a top view of the laminae of the engine cooler provided with straight pipe arrangement according to the invention, Figure 4 is a top view showing that particular part of a lamella on which the elementary fins are arranged, Figure 5 is a top view of the elementary pair of fins in bent-up position, Figure 6 is a side view of the elementary pair of fins, Figure 7 is a top view of the enlarged section of the engine cooling lamella between two pipes, and Figure 8 shows a modification of Figure 7.

Figure 1 illustrates the longitudinal section of the conventional engine cooler, showing a flat pipe 1 carrying the medium to be cooled, i.e.

water or oil, and thin lamellae (fins) 2 pulled perpendicularly over the pipe. The medium to be cooled flows in the pipe 1, while the coolant, e.g.

air, flows perpendicularly to the lamellae 2.

Figure 2 is a top plan view showing a detail of the engine cooling lamella formed as one of the possible solutions according to the invention. The diagram refers to a cooler with displaced pipe arrangement. The flat pipes 1 carrying the coolant and the fins 2 fixed to them are visible in Figure 2.

The elementary pairs of fins 3 in the section between the pipes are also visible. Three elementary pairs of fins 3 are shown between two adjacent rows of pipes. Looking from the direction of air flow the elementary pairs of fins are arranged behind each row of pipes.

Figure 3, for the case of pipes 1 with a straight arrangement, clearly illustrates that two or more (three in the example given in the figure) turbulence-forming and spaced elementary pairs of fins 3 bent up at 900 are arranged symmetrically to the centre-line A of the field of fins 3, each surrounded by two adjacent flat pipes.

Figures Ai 6 explain the technology of building up the elementary pairs of fins 3. Figure 4 shows sections, a, b, c, along which the plates are cut out. The elementary pair of fins is bent up at 900 along edge d. Figure 5 shows the top plan view of the bent-up pair of fins. Edge 4 of the pair of fins 3 is slightly bent or curved, the bend or the tangent drawn to the curve being at an angle of 0--1 50 to the direction of air flow. Figure 6 shows a side view of one of the bent-up elementary fins 3. Here the height o of the bentup part of the fins 3 corresponds to the spacing of the cooling lamellae 2.

Figure 7 shows a top plan view of the enlarged section of the lamella 2 between two rows of pipes 1. In the Figure the ratio of the plain sand finned fields m equals one and this value can not be less than one. Finally the diagram shows that the width sz of cooling pipes 1 is less than the distance t between the elementary pair of fins.

This arrangement is applicable especially in case of displaced lamellae, since in this case the elementary fins are capable of guiding the air into the vicinity of the next pipe, to the bottom of the pipe, i.e. to the warmest section.

A suitable solution for coolers with larger lamella distance is shown in Figure 8. In this case in order to avoid increase in the distance between the pipes 1, which would entail a deterioration of the fin's efficiency, the elements of the pair of fins 3 are displaced.

Claims

1. An oil or water cooler suitable for stationary or motor vehicle engines, consisting of lamellae perpendicularly pulled over pipes of rectangular or elliptical cross-section arranged in offset or straight rows, wherein two or more turbulenceforming and spaced elementary pairs of fins cut out to a trapezoidal shape from the original plane of the plate and bent up at 900 are arranged symmetrically about the centre line of the lamellafield surrounded by two pipes.

2. An engine cooler as claimed in claim 1, wherein the elementary pair of fins is arranged on the lamella in such a way that the ratio of the plain sections s and the interrupted sections m equals to or is greater than one.

3. An engine cooler as claimed in claim 1 or 2, wherein those sections of the elementary pairs of fins bent up at 900 which are arranged in parallel with the flow, are bent or curved, and the tangent drawn to the bend or curves is at an angle of 0- 1 50 to the flow direction of the coolant.

4. An engine cooler as claimed in any of claims 1 to 3, wherein the height of the elementary pairs of fins bent up at 900 equals the distance between the fins.

5. An engine cooler as claimed in any of claims 1 to 4, wherein the bent up elementary pairs of fins are arranged behind each row of pipes symmetrically about the centre line of the row of pipes in such a way that the distance t between the elementary pairs of fins is greater than the width sz of the pipes perpendicular to the air flow.

6. An engine cooler as claimed in any of claims 1 to 5, wherein certain elements of the pairs of fins are displaced and arranged symmetrically to the bisector of the distance between the pipes.

7. An engine cooler or radiator having pipes or tubes of elongated cross-section for carrying a flow of cooling liquid, a plurality of spaced plates spanning the tubes in planes substantially perpendicular to the flow direction of the cooling liquid, each plate having a plurality of trapezoidally shaped fins formed from material cut from the plate and bent through substantially 900 from the plane of the plate, the fins being symmetrically arranged in the space between adjacent pipes or tubes and serving not only as heat dissipating surfaces but also to increase turbulence of cooling air passing between the plates.

8. An engine cooler constructed and arranged substantially as herein particularly described and illustrated in Figures 2 to 8 of the accompanying drawings.