Turbulence-producing insert for a heat exchanger

Abstract

 An insert 10 for placing in the liquid-carrying tubes 16,18 of a heat exchanger has two connected strands 12,14 for placing in two parallel tubes 16,18. The strands 12,14 are connected to one another to prevent rotation in the tubes and have non-return formations 26,28 at their opposite ends to resist return movement of the strands 12,14 up the tubes 16,18.

Description

[0001] This invention relates to a turbulence-producing insert for a heat exchanger and is particularly, though not exclusively, suitable for use in a cooling radiator of a motor vehicle.

[0002] It is known that the efficiency of heat transfer can be improved in a heat exchanger if the heat exchange media can be forced to perform turbulent flow through the exchanger. It is also known to insert turbulence-­producing inserts in liquid passages of a heat exchanger in order to induce turbulent flow. Problems do however arise in retaining the inserts in their desired positions within the tubes once the heat exchanger is in operation.

[0003] According to the present invention, there is provided a turbulence-producing insert for insertion in liquid-­conducting passages of a heat exchanger, the insert comprising two parallel turbulence-producing strands for insertion into parallel liquid-conducting passages with the strands being joined to one another at one end and each having a formation at the other end which can pass through a passage in one direction, but is unable to return through the passage in the other direction.

[0004] The formation is preferably constructed so that, in the relaxed state, the maximum width of the formation is greater than the cross-sectional area of the strand. The cross-sectional area of the strand is the area through which the turbulence-producing part of the strand will just pass, and will generally correspond to the internal diameter of the heat exchanger passage.

[0005] The one ends of the strands preferably have a lip which can be in the form of a cross bar to limit the depth of insertion of the strands in the passages.

[0006] The inserts are preferably made from plastics material, normally injection moulded.

[0007] The turbulence-producing strands can have a helical shape, a ladder shape or any other turbulence producing shape.

[0008] The insert is preferably adapted to fit into cylindrical section passages such as are fourd in a mechanically assembled radiator in which cylindrical tubes are expanded outwardly into thermal contact with external fins.

[0009] The use of a formation which can only pass through the passage in one direction ensures that once the insert is in place, it cannot be dislodged under the influence of the heat exchange liquid flowing through. The connection of two strands to one another prevents either of the strands from rotating in its respective passage. Although two connected inserts is preferred, it would be technically feasible to have three or four or even more strands connected together to form one insert.

[0010] The invention will now be further described, by way of example, with reference to the accompanying drawing, in which :

Figure l is a section through two passages of a heat exchanger with an insert according to the invention in place;

Figure 2 is a view of the insert in the direction of the arrow A from Figure 1; and

Figure 3 is a side view of the insert.

[0011] The insert 10 has strands 12 and 14 inserted in passages 16 and 18 of the heat exchanger. In the example, the passages 16 and 18 are tubular and of course are only two out of a much larger number of tubes which make up a heat exchanger. Heat exchange fins (not shown) will be mounted on the tubes 16 and 18, to form a heat exchanger core in a conventional manner.

[0012] At one end, the strands 12, 14 have a head formation 20 with a cross bar 22 which limits the depth of insertion of the strands into the tubes. There is also a handle portion 24 which assists in handling and insertion.

[0013] At the other ends of the strands, non-return formations 26, 28 are moulded each with wings 30 which are compressed when the strands are pushed into the tubes, but which expand once the ends extend from the bottoms of the tubes to prevent removal.

[0014] It is important that the formations at the opposite ends of the inserts should not restrict liquid flow to and from the tubes, so they are flat in cross section as can be seen from Figures 2 and 3.

[0015] In use, the inserts can be assembled to the heat exchanger simply by introducing the tips 26, 28 into the tops of the tubes and then pushing the strands fully home. The strands are then firmly held in position and resist any axial movement along the tubes which might be caused by the pressure of liquid in the tubes, and also resist rotation in the tubes.

Claims

1. A turbulence-producing insert for insertion in liquid-conducting passages of a heat exchanger, characterised by two parallel turbulence-producing strands (12,14) for insertion into parallel liquid-conducting passages (16,18) with the strands (12,14) being joined to one another at one end and each having a formation (26,28) at the other end which can pass through a passage (16,18) in one direction, but is unable to return through the passage in the other direction.

2. An insert as claimed in Claim 1, characterised in that the formation (26,28) is constructed so that, in the relaxed state, the maximum width of the formation (26,28) is greater than the cross-sectional area of the strand (12,14).

3. An insert as claimed in Claim l or Claim 2, characterised in that the one ends of the strands (12,14) have a lip to limit the depth of insertion of the strands in the passages.

4. An insert as claimed in Claim 3, characterised in that the lip is in the form of a cross bar (22).

5. An insert as claimed in any preceding claim, characterised in that the insert is injection moulded from plastics material.

6. An insert as claimed in any preceding claim, characterised in that the strands (12,14) are adapted to fit into passages (16,18) of uniform circular cross section.

Drawing