Title of Invention

"PLATE HEAT EXCHANGER"

Abstract

Plate heat exchanger comprising plates disposed one behind the other and connected to form a packet, which, by means of an elastic seal (4) emplaced in each instance between adjoining plates into a peripheral groove (3), form closed channels alternately for a medium giving off heat and one absorbing heat, which via inlet and outlet openings (5-8), aligned with one another, of the plates can be charged with the particular medium, wherein the seals are mechanically fastened on one of the plates, which they seal against one another, thereby that elastic nipples, developed integrally with the seals and disposed at intervals on their longitudinal extent, are pressed into associated holes of the plates, characterized in that the nipples (25) have a cross section which is smaller than the penetration cross section of the holes (26), but project beyond it at several sites on the circumstance.

Full Text

The present invention relates to a plate heat exchanger, comprising plates disposed one behind the other and connected to form a packet, according to the preambles of claims 1 and 6. Before the plates of a plate heat exchanger are suspended in a frame and pressed together to form a packet, seals are fixed in grooves which facilitates handling the plates during the assembly. A known manner of fastening the seals comprises adhering these in the groove, wherein the adhesive means for the sealing effect itself is irrelevant but rather serves for the correct position fixing on the plates. This adhesion technique has some disadvantages For example, before the application of the adhesive means, the grooves must be cleaned of, for example, oil and hit residues in order for the adhesion effect not to be impaired. Subsequently the adhesive means itself must be applied. All of this is rather time consuming. Problems are also encountered in the maintenance of plate heat exchangers when a seal needs to be replaced. For this purpose the old seal must be removed and subsequently the groove must be cleaned of the adhesive means. An inspection of the groove bottom and the seal is also only possible, for example after the cleaning work on the dismounted heat exchanger, if the adhesion connection is previously destroyed. Due to these disadvantages and the fact that in some technical fields, such as for example in medicine and food, adhesive means are to be avoided as much as possible plate beat exchangers hax'e been developed in which the seals are fastened mechanically, thus without adhesive means, on the plates. One feasibility known in the relevant technology for the adhesive means-free seal fastening comprises that elastic nipples or projections, integrally developed with the seals, are brought into press fit with associated holes or openings in the plates. According to GB 2 071 303 A, GB 2 075 656 A and EP 0 134 155 Al the nipples should have overdimensions relative to the holes such that they can readily be pressed into the holes and can be pulled out again/ It is therein to be ensured that the seal is fixed securely at the intended site. This solution entails problems since the nipples as well as the seal as cast parts are subject to tolerance fluctuations. If the radial overdimension of the nipple? is too large, they can only be pressed into the holes with difficulty or not at all. If this is, nevertheless, successful, the nipples tear off when the seal is removed, for example during inspection or cleaning work, such that the seal must be replaced by a new seal. The problem of tolerances in the radial nipple dimensions is solved through a plate heat exchanger proposed in EP 0 039 229 A2. Here, the nipples are provided on webs disposed laterally to the seal and developed integrally with it, from which the nipples project downwardly. Through the webs extends a pocket hole into the nipples. To fasten the seal, the nipples are positioned above holes, associated with them, on the plates. Subsequently a pin or the like tool is introduced into the pocket hole and the nipples are then stretched by pressure onto the pin such that they become significantly thinner and can be placed into the holes without any problems. After the removal of the pin the nipples contract again to their original dimension where by the ends of the nipples inserted through the holes expand to form a head covering the hole from below. The seals are consequently fastened securely on the plates Of disadvantage in this technique is that tools are necessary to press the nipples in. Furthermore, during inspections or maintenance work requiring the removal of the seal, the above described consequences occur. Lastly, EP 0 123 379 Bl discloses a plate heat exchanger in which the seal is fastened on the plate by means of elastic projections integrally developed with it, which extend into associated openings in the groove bottom. The openings are developed such that they comprise an insertion and pull-out region into which the projections can freely be moved, and from which they can be moved out again, along the margin of the openings without force. From this region the projections can be moved into a blocking region of the openings, in which the motion of the projections into the openings, respectively out of them again, is counteracted by strong resistance by compression between the projections and the margins of the openings, wherein moving the projections from the insertion and pull-out position into the blocked position, and conversely, is possible due to the elasticity (resiliency) of the seal. The present invention addresses the problem in a plate heat exchanger of the species of providing a simple solution for the mechanical fastening of the seals on the plates, which nevertheless permits the secure hold and the problem-free removal of the seals. This problem is solved with a plate heat exchanger with the characteristics of claims 1 or of claim 6. Based on the solution within the invention according to claim 1 the nipples when they are inserted into the holes are not pressed on their entire circumference but rather only locally at those sites at which they project beyond the margin of the holes. Since their cross section is smaller than the penetration area of the holes, at the other sites there is still tolerance between the circumference of the nipples and the margin of the holes Due to the elasticity of the nipples, their compressed material can expand into these free volumes, which leads to a decrease'of the compression and consequently facilitates pressing the nipples into the holes. Through this displacement mechanism overtolerances in the radial dimensions of the nipples is extremely well compensated or, expressed differently, it is possible to work with relatively greater radial overdimensions than is possible within the state of the art In implementing the invention either the holes can therein haven polygonal penetration cross section and the nipples a circular cross section or conversely, the nipples can have a polygonal and the holes a circular cross section. In an advantageous embodiment of the invention the.margin of the holes is developed as a draw-through pointing in the direction of insertion of the nipples. This forming of the holes has various advantages. Thus, relative to prior art, the contart area between nipple and hole is increased. This provides greater structuring freedom in the optimization of the characteristics, essential to the invention, in their interrelationship. Furthermore, thereby the immersion of the. nipples into the holes is facilitated since the ends of the nipples when being inserted into the holes run against an encompassing radius on the margin of the hole, which, when establishing the draw-through, results automatically. This radius permits also providing a radius at the transition from nipple to seal. For one, this has advantages with respect to fabrication engineering during the production of the seal and, for another, it reduces the danger that the nipples are sheared off at this site during motions of the plates. In further development of the invention it is of advantage in facilitating the insertion of the nipples into the holes if the ends of the nipples are shaped conically. In a plate heat exchanger according to claim 6 the problem is solved thereby that the margin of the holes is developed as a draw-through pointing in the insertion direction of the nipples. This forming of the holes has various advantages. Thus, for one, the contact area between nipple and hole is increased. Thereby the radial overdimension of the nipples required according to prior art can be decreased while maintaining a secure hold of the seal This permits the nipples to be pressed into and pulled out of the holes more readily. For another, the immersion of the nipples into the holes is facilitated since the ends of the nipples when they are inserted into the holes run against an encompassing radius on the margin of the hole, which results automatically when establishing the draw-through. This radius also permits providing a radius at the transition from nipple to seal. This, for one, has advantages with respect to fabrication engineering during the production of the seal and, for another, it reduces the danger that the nipples are sheared off at this site during 'motions of the plates. In implementation of the invention according to claim 6, the nipples have a cross section which is smaller than the penetration cross section of the holes, but project beyond this at several sites on the circumference. The nipples can therein have a polygonal and die holes a circular cross section, or conversely, the holes can have a polygonal penetration cross section and the nipples a circular cross section. Due to this futher development, the nipples when they are inserted into the holes are not pressed on their entire circumference but rather only locally at those sites at which they project beyond the margin of the holes. Since their cross section is smaller than the penetration area of the holes, at the other sites there is still tolerance between the circumference of the nipples and the margin of the holes. Due to the elasticity of the nipples, their compressed material can expand into these free volumes, which leads to a decrease of the compression and consequently facilitates pressing the nipples into the holes. Tins displacement mechanism is of advantage with the contact area between rupple and hole margin increased through the draw-throughs, since it provides greater structuring freedom in optimizing the interrelationship of draw-through area and radial over-dimension of the nipple or, expressed differently, in the optimization of the targeted values, namely secure hold and problem-free removal of the seal Accordingly, the present invention relates to plate heat exchanger comprising plates disposed one behind the other and connected to form a packet, which, by means of an elastic seal emplaced in each instance between adjoining plates into a peripheral groove, form closed channels alternately for a medium giving off heat and one absorbing heat, which via inlet and outlet openings, aligned with one another, of the plates can be charged with the particular medium, wherein the seals are mechanically fastened on one of the plates, which they seal against one another, thereby mat elastic nipples, developed integrally with the seals and disposed at intervals on their longitudinal extent, are pressed into associated holes of the plates, characterized in that the nipples (25) have a cross section which is smaller titan the penetration cross section of the holes (26), but project beyond it at several sites on the circumstance. In the following, the invention will be explained in further detail in conjunction with an embodiment example and an associated drawing. Therein depict: Fig. 1 a schematic lop view onto a plate of a plate heat exchanger, Fig. 2 a sectional perspective view onto the margin region of a plate with emplaced seal, Fig. 3 a section A-A according to Figure 2 at an enlarged scale with the additional representation of an emplaced second plate with inserted seal, Fig. 4 a section B-B according to Figure 2 at an enlarged scale, also with the additional representation of an emplaced second plate with inserted seal, Fig. 5 a section C-C according to Figure 2 at an enlarged scale also with the additional representation of an emplaced second plate with inserted seal, Fig. 6 a section D-D according to Figure 5 at an enlarged scale, and Fig. 7 a section F.-E according to Figure 5 at an enlarged scale. Figure 1 shows a plate 1 of a plate heat exchanger with a heat exchange area 2 which is framed by a seal 4 placed into a peripheral groove 3 and comprised of a synthetic rubber or another elastic sealing material. At the comers of the plate 1 are provided inlet and outlet openings 5-8 for the heat exchange media. While in the depicted plate 1 the inlet and outlet openings 5, 6 are encompassed by the seal 4, the seal in the plate 1 disposed in front and behind the plate 1, plates not shown in the Figure, encompasses the inlet and outlet openings 7 and 8. In this way between the plates bundled into a packet, alternately flow channels for a medium giving off heat and a medium absorbing heat is formed. In so far the plate heat exchanger corresponds to the structure known from prior art and therefore does not require further explanations. Seal 4 is fixed in the groove 3 without using any adhesive means. For this purpose on the side facing away from the heat exchanger area 2 are provided retaining parts 9 developed integrally with the groove, which are disposed at suitable intervals from one another on the circumference of the seal 4 and project laterally from these. Such a retaining part 9 is depicted perspectively in Figure 2, which shows a margin section of plate 1. It should be stated here that in the representation according to Figure 2 a second plate V, which is evident in the sectional representations according to Figures 3-5, has been omitted for reasons of clarity. It is evident in Figure 2 that the groove 3 is formed of an inner side wall 10, decreasing from the level of the heat exchange area 2, a groove bottom 11, and an outer side wall 12, rising again to the level of the heat exchange area 1, wherein the latter is adjoined by a plate margin 13. This plate margin 13 is not level but rather is formed by channels 14 and 15 alternately opening upwardly and downwardly as well as outwardly and having the form of a ttapezoid in cross section. The bottom 16 of the channels 14 are at the level of the groove bottom 11 and the bottoms 17 of channels 15 at the level of the heat exchange area 2. This "corrugation" of the plate margin 13 is formed thereby that the channels 14 of the sheet metal slab of plate 1 are pressed downwardly as troughs closed toward the groove 3- Thereby between the front walls 18 of channels 14 and the outer side wall 12 of groove 3, bridges 19 are remaining. The hollow spaces 20 formed underneath these bridges 19 connect the channels 15, which extend up to the outer side wall 12 of groove 3 on the underside of plate 1. Each retaining part 9 extends in each instance into two adjacent channels 14 and a channel 15 disposed in between. It is connected with seal 4 via a web 21 extending over its entire width. The form of this web 21 is not evident in Figure 2, however is disclospd when the cross sectional representations according to Figure 3 and 4 are viewed synoptically. Based thereon it is evident that the web 21 is thinner in the region of bottom 17 of channel 15 than it is in the region of the bridges between the two channels 14 and the outer side wall 12 of groove 3, i.e., the web 21 is reinforced in these regions. In order to receive these reinforced regions of web 21, the bridges of channels 14 into which the retaining part 9 extends, in comparison to the remaining bridges 19 are indented downwardly by the magnitude of the reinforcement such that the bridges 19.1 formed thereby have a lesser height than the bridges 19. This forming is again disclosed by viewing Figures 3 and 4 synoptically. Adjoining the xypb 21 are two extensions 22, which, at the end facing the seal 4, are connected with one another by a transverse member 23, which is adjoined, with respect to the plate margin 13, toward the outside by a thinner intermediate part 24, also connecting the extensions 22, whose underside forms a prolongation of web [sic: bridge] 19. When installed, the extensions 22 lie within the associated channels 14, while the intermediate piece [sic part] rests on the bottom 17 of the channel 15 disposed in-between. As is evident in particular in Figure 5, the cross section of the extensions 22 is selected such that they fill completely the hexagonal cross section formed by the channels 14 of platf 1 and the channels 15 of plate V disposed behind or, with respect to the drawing, superposed, expressed differently, they are in contact formfittingly in the associated channels 14 and 15 facing one another. Since the channels 14, 15 are open toward the outside, thus toward the environment, the retaining parts 9 can expand in this direction, whereby thermal and mechanical stresses are reduced and thus deformations of the plate margin 13 are avoided. Figure 5 in connection with Figure 3 shows that the bottom 16 of channel 14 of plate 1, which is disposed above the intermediate part 24, is raised in the rear region by the thickness of the intermediate part 24, i.e. it conforms so-to-speak from above to the intermediate part 24. It can also be seen in Figure 3 that the transverse member 23, after the assembly, substantially fills the hollow space 20 formed under bridge 19. The described form-fit development of the retaining parts 9 with the plates 1, covering them, stabilizes the orientation of plates 1, V in the plate packet and prevents, or reduces, in cooperation with conventional metal guidance elements developed on the plates, motions of plates ], 1 in the plate plane during operation due to the internal pressure of the heat exchange media. Since the retaining parts 9, and thus also seal 4, in the embodiment described so far, rest only loosely on plate 1, measures for fastening must be taken in order for sea] 4 to be reliably fixed in groove 3 during the assembly in the preceding handling. For this purpose a nipple 25, integrally developed with the retaining part 9, is provided, which projects downwardly and, with the seal 4 mounted, projects through a circular hole 26 in plate 1. The margin of this hole 26 is developed as a draw-through 27 pointing in the direction of insertion of nipple 25. The radius at the hole margin, formed due to the draw-through 27, facilitates inserting the nipple 25 into the hole 26. The transition of the nipple 25 to the- intermediate part 24 can simultaneously also be implemented with this radius. This development prevents, for one, the shearing forces acting onto the nipple 25 by the margin of the hole 26 and facilitates, for another, the production since radii can be realized more readily in a casting mold. To facilitate the insertion into the hole 26 further, the tip of the rupple 25 is developed in the form of a truncated cone. In contrast to the circular cross section of hole 26, nipple 25 has a trigonal cross section, wherein the edges 29 are rounded off. This development can be seen most clearly in Figure 6. In this representation a circle 28 enveloping the nipple cross section is drawn in. Diameter Dl of this circle 28 is greater than the inner diameter D2 of the hole 26. But simultaneously the cross sectional area of nipple 25 is smaller than the penetration cross section of hole 26. If, during the mounting of seal 4, the nipple 25 is pressed into hole 26, it becomes centered due to its conical tip and the radius at the hole margin itself. Simultaneously its penetration into hole 26 is facilitated. When the nipple 25 is pressed in further, its material is compressed at the positions projecting over the inner diameter of hole 26, which, in this case, are the rounded-off edges 29. But, due to its elasticity it can expand into the free volumes between the cross section of nipple 25 and the inner wall of the hole. In Figure 7 these free volumes are provided with the reference number 30 Since the material of nipple 25 thus has radial and axial freedom of flow, the pressmg-in and pulling-out of nipple 25 into or out of the hole 26 is facilitated. Simultaneously the required clamp-fit of nipple 25 in hole 26 is ensured, which is even further improved due to the greater inner wall area of hole 26 provided with the draw-through 27. WE CLAIM: 1. Plate heat exchanger comprising plates disposed one behind the other and connected to form a packet, which, by means of an elastic seal (4) emplaced in each instance between adjoining plates into a peripheral groove (3), form closed channels alternately for a medium giving off heat and one absorbing heat, which via inlet and outlet openings (5-8), aligned with one another, of the plates can be charged with the particular medium, wherein the seals are mechanically fastened on one of the plates, which they seal against one another, thereby that elastic nipples, developed integrally with the seals and disposed at intervals on their longitudinal extent, are pressed into associated holes of the plates, characterized in that the nipples (25) have a cross section which is smaller than the penetration cross section of the holes (26), but project beyond it at several sites on the circumstance. 2. Plate heat exchanger as claimed in claim 1, wherein said nipples (25) have a polygonal and the holes (26) a circular cross section. 3. Plate heat exchanger as claimed in claim 1, wherein said holes (26) have a polygonal penetration cross section and the nipples (25) a circular cross section. 4. Plate heat exchanger as claimed in one of the preceding claims, wherein the margin of the holes (26) is developed as a draw-through (27) pointing in the insertion direction of the nipples (25). 5. Plate heat exchanger as claimed in one of the preceding claims, wherein the tip of the nipples (25) is shaped conically.

Documents:

774-del-2001-abstract.pdf

774-del-2001-claims.pdf

774-del-2001-correspondence-others.pdf

774-del-2001-correspondence-po.pdf

774-del-2001-description (complete).pdf

774-del-2001-drawings.pdf

774-del-2001-form-1.pdf

774-del-2001-form-18.pdf

774-del-2001-form-2.pdf

774-del-2001-form-3.pdf

774-del-2001-form-5.pdf

774-del-2001-gpa.pdf

774-del-2001-petition-137.pdf

774-del-2001-petition-138.pdf