The present invention relates to an arrangement for a plate heat exchanger comprising a number of essentially rectangular plates, of which the outermost plates are supporting plates, one of which is provided with cut-outs for the attachment of inlet and outlet sleeve connections.

A plate heat exchanger of this kind is described in more detail in Swedish Patent Application No. 8501599-8, from which this Application is derived.

A disadvantage of the previously disclosed design is the fact that the outermost plates, the so-called supporting plates in which inlet and outlet sleeve connections are arranged at least on one side of the heat exchanger, can be subjected to stresses resulting from the residual thermal stresses associated with the manufacturing process in conjunction with the operating stresses (pressure fluctuations, vibrations and thermal stresses), which can achieve a value such that fractures may occur not only in the joint between the sleeve connection and the supporting plate, but also between the latter and adjacent heat exchanger plates, resulting in leakage.

In order to avoid fractures of this kind in the joint between the inlet and outlet sleeve connections and the supporting plate on the one hand, and between the latter and an adjacent heat exchanger plate on the other hand, the aforementioned supporting plates are provided in accordance with the invention with a number of folds running, across the plate, with the folds in the plate provided with cut-outs being arranged between the cut-outs.

The construction of a plate heat exchanger is intended to be explained below in more detail with reference to the accompanying drawing, in which Fig. 1a illustrates schematically a plate heat exchanger viewed from above with a supporting plate and sleeve

couplings, and Fig. 1b illustrates a plate heat exchanger with a supporting plate viewed from below. Fig. 2 shows a cross-section through a plate heat exchanger. Fig. 3 shows a cross-section of the aforementioned heat exchanger.

The reference 1 is used in the drawing to designate a plate heat exchanger which comprises a number of plates 2a, 2b, 2c, 2d and inlet and outlet sleeve couplings 3, 4, 5, 6. The plates 2a, 2b, 2c and 2d are essentially rectangular and have a relief pattern 7 and a border 8 running around its perimeter. This is off-set in two ledges 9, 10 by approximately one thickness of the plate so that the plates 2a, 2b, 2c and 2d are capable of being inserted into one another. This means that the border 8 can be divided up into three steps 8a, 8b, 8c. The first step, the so-called pattern step, is so arranged as to enclose the relief pattern 7 of the plate. The second step, which is referred to as the screening step, is intended to integrate the flow area for the flow channel of the subsequent plate. The third step 8c is intended to constitute a joining- and sealing element with the second step of the adjacent plate and is accordingly described as the joint step.

The first ledge 9 shall be situated at a distance from the bend in the border 8 which is approximately equal to the depth of the pattern 7 in the. plate 2. The second ledge 10 shall be situated at a distance from the bend in the border 8 which is approximately equal to twice the depth of the pattern.

In a plate heat exchanger of this kind the outermost plates are so-called supporting plates 11a, 11b (see Figs. 2, 3). One of these 11a is provided with cut-outs 12a, b for the attachment of the inlet and outlet sleeve couplings 4, 5.

According to the invention the supporting plates 11a, 11b are executed with a number of folds 13 running across each plate. In the case of the supporting plate 11a with cut-outs for the sleeve couplings, the folds 13 are arranged between the cut-outs. The

folds are intended to absorb the dimensional variations in the plate heat exchanger 1 which can occur in the case of -major variations in temperature, both in conjunction with soldering and when the heat exchanger is in use. The folded supporting plates in this case operate in a similar fashion to a concertina bellows.