MXPA06001032A - Heat exchanger and method for the production thereof - Google Patents

Abstract

The invention relates to a heat exchanger which is especially used as an oil cooler in vehicles, and a method for the production thereof. A heat exchanger which is especially used as an oil cooler in the motor vehicle industry consists of interconnected plates. Outwardly closed cavities are embodied between the plates. Said cavities are alternately supplied with a first or second medium by means of respectively at least one supply line and one discharge line, and a corresponding medium flows through them. The plates are profiled in such a way that contact points are created between the respective profiles of the plate, andsaid plates are interconnected in the region of said contact points. The plates are designed such that the current from the first or second medium forming between the plates, from the corresponding supply line to the corresponding discharge line, does not follow a linear path.

Description

HEAT EXCHANGER AND METHOD FOR ITS PRODUCTION FIELD OF THE INVENTION The present invention relates to a heat exchanger of the type that is used especially in vehicles for cooling the oil, as well as to a process for its production.

BACKGROUND OF THE INVENTION So-called plate exchangers are known, which are formed from a stack of plates next to one another. Between the plates, hollow spaces are formed, through which alternately a first and a second medium flow. In addition to its use as a refrigerant, in which for example the first medium can be cold water and the second medium can be the working medium to be cooled, which is the engine oil in the case of an oil cooler. an internal combustion engine, it is also possible to use as an evaporator in a cooling device such as, for example, the air conditioning of a vehicle, in which one of the two means is the refrigerant and the other. It is the cold medium. In this case it is known that the plates are profiled in such a way that contact zones are formed between the plates. In the area of the contact areas, the plates are fixed to each other. Thus the plates are sealed against each other with respect to the outside, so that the cooling medium or the working medium flows exclusively in the hollow space. The first and second means are fed here by means of a corresponding supply conduit and are withdrawn through a discharge conduit. Here the inlet ducts serve and the outlet ducts serve as collecting ducts, in which the fluid flow of all corresponding hollow spaces is conducted or withdrawn. Usually in these plate heat exchangers, there are pieces that increase the turbulence to improve heat transfer and to increase the surface, pieces that are placed in the fluid channels and fixedly attached to the heat exchanger plates. With this, in addition to the thermodynamic properties of the channel, the stability of the cooler is considerably improved. A disadvantage of these turbulence plates is that during the production of the through holes the chip formation easily occurs which can cause the flowing medium to become contaminated. As a result, impurities are easily stored in the area of the turbulence plates. With this, the flow through the hollow space can be prevented undesired. Consequently, it is necessary to produce an additional component, which, thanks to the high costs of production and materials, leads to an increase in the heat exchanger.

SUMMARY OF THE INVENTION It is therefore the task of the invention to produce a heat exchanger that does not have the disadvantages of known heat exchangers. This task is solved by means of a plate heat exchanger according to the invention, which can be produced in a particularly advantageous manner by means of the process according to the invention. A heat exchanger, such as that which is found as an oil cooler in motor vehicles, is formed by plates joined together. Between the plates, hollow spaces are formed which are closed outwards. The hollow spaces are alternately provided with at least one feed duct and a discharge duct for a first medium and a second medium, and the corresponding medium flows through those hollow spaces. For this, the plates are profiled in such a way that contact zones are formed between the profiles of the plates. In these contact areas are the plates joined together. The plates are constructed in such a way that the current of the first or second means, which is formed between the plates from the corresponding supply conduit to the corresponding discharge conduit, does not follow a straight line. This measure has the advantage that the flowing medium is partially deflected multiple times from its flow path. This improves the distribution of fluids across the width of the plates. Depending on the fluidity (viscosity) of the fluid medium under some circumstances there are also turbulent currents The constant changes in the direction of the fluid in the channel and the eddy that forms under certain circumstances in the area of the open corrugated channel, they break the dividing layers that are always formed. This leads to a better heat transfer. According to a preferred embodiment of the invention, the plates have a repeated wavy profile, which at least in one direction extends transverse to the direction of flow, which is the direct connection of the entry point of the medium to the exit point. Around that direction the wavy profile advances in a zigzag pattern. A corrugated profile of this type simply forms flow conduction zones, which are suitable for conducting the flow of the medium flowing through the hollow spaces. The current during its course is advantageously diverted multiple times, and this is especially not only in the plane of the plates but outside that plane of the plates. In areas where the distance between the plates has different dimensions, the speed of the current varies under certain circumstances. Simultaneously advantageously it is achieved that the medium is distributed over the entire surface of the plate and thus an optimal use of the entire heat exchange surface is achieved. According to another embodiment, the corrugated profile between the flow areas has branches that extend in a straight line, the course of the corrugated profile being characterized by the length of the branches, the angle formed between the branches and the depth of the profile of the branches. the ripples. The cross section of the profile of the corrugations is determined by means of the course in the area of the branch as well as in the zone of curves, in preferred embodiments a variation of that transverse shape may be provided in those areas. The wavy profile that advances in a zigzag pattern is characterized here especially by means of the length of the branch, the angle between neighboring branches and the depth of the profile. Preferred embodiments of the invention provide that the length of the branches are in the range of between 8 and 155 m, preferably in the range of 9 to 12 mm. The typical values of the depth of the profile that is measured for example with the distance between a crest or a median plane of the plate, are in the range of 0.3 to 1.5 mm. For many applications, a profile depth between 0.5 and 1 mm may be advantageous, values of approximately 0.75 mm being preferred. The angle between two branches of the corrugated profile is preferably between 45 and 135 °. In particular, the values of approximately 90 ° represent a good compromise with regard to the fluid distribution, the flow velocity and the flow power of the heat exchanger. The length of the branch and the angle of the branch influence between the function of flow conduction between the corrugated profiles, but also the placement of the contact zones of neighboring plates, which are required for the stability of the heat exchanger. The inherent rigidity of the plates against a pressure stroke produced by the means can not be guaranteed without a support, when a reduced thickness of the plate has been selected, which is desirable in many applications for reasons of weight saving as well as heat exchange. In a preferred embodiment, the joining of the plates in the contact areas is carried out by means of brazing. The selection of the lengths and the angles of the branches is preferably carried out depending on the flowing medium and its viscosity. The length and angle of the branch have a great influence on the flow rates that occur and the heat exchange associated with these speeds, so that they can be adapted to the final use in question. The aforementioned values relate here in particular to the use of heat exchangers such as oil coolers in motor vehicles, and where the heat exchange between the engine oil and the cooling water is carried out. They also depend naturally on the dimensions of the plate and the intermediate space formed between the separation of the plates. The shape of the corrugated profile is essentially determined by the shape of the cross section perpendicular to the outer edge of the profile in that area as well as the sequence of profiles determined by the division in the course transverse to the direction in which it extends. a wavy profile on the plate. The preferred modalities foresee a constant division, this is a fixed distance between two wavy profiles that are close to each other. The shaping of the corrugated profile is then advantageous when it has a flat area on the outer side of the back part of the wave. The flat area then has a width of 0.1 to 0.4 mm in particular. The flat zone allows a good flat support between neighboring plates and with this a light and stable production of the support or the joint, as for example by brazing, between neighboring plates. The material of the plates is preferably aluminum. This material has the advantage that it has a low density and simultaneously allows easy production of the corrugated profile, for example by means of stamping. For the production of the connection between two neighboring plates in the area of the contact points as well as in the area of the edges, it can be completely covered on one side with a welding aid such as, for example, for brazing. Depending on the selection of the welding aid as well as the thickness of the applied layer of the welding aid, a coating can also be carried out with the welding aid on both sides. The coating with auxiliary welding, especially in the area of the edges and of the inlet and outlet ducts in the block, must serve for the reliable production of a fluid-tight connection of two plates to each other in a joining process with a joining tool (brazing oven) without using other instruments or auxiliary materials. In another embodiment, the plates can be provided with perforations which, in the area of the heat exchanger, serve as inlet and outlet conduits, and the axes of the perforation extend perpendicularly to the plane of the plates. Here the orifices are applied in particular in an elevated area in front of the basic surface of the plates. The raised area is preferably raised in such a way that in each second intermediate space between the plates an airtight connection is formed between the raised area and the next plate, such that only in each second intermediate space between the plates, there is a junction of fluid between the perforations and the intermediate zone of the plates. By means of this measure it is possible to enter and exit the fluid from the intermediate spaces of the plate, without the need to use ducts, in such a way that through these intermediate spaces either the cooling medium or the medium flows. job. Here, the fluid-tight connection between an elevated area and an adjacent plate can not only take place by means of a form closure, but also by means of another joining technique, for example by means of brazing. For this, the raised area has a preferably flat support section, which forms a fluid-tight connection with a preferably flat bearing surface of the neighboring plate. The raised area as well as the perforations in the raised area can not only have a circular cross-section, also oval or longitudinal-shaped constructions are possible and advantageous. In this case the longest axis of the two axes of the construction in the form of a longitudinal hole should preferably be placed transverse to the main direction of the fluid. This measure also serves to improve the heat exchange between both media, since in the case of an equal total expansion of the plates a greater surface for the heat exchange is obtained. Furthermore, it is possible that in the area of the inlet ducts and of the orifices associated with the inlet ducts, distributing channels are provided, which preferably are shaped as a corrugated profile. It represents one of the especially preferred embodiments of the invention when the corrugated profiles of the distributing channels differ from the other corrugated profiles with respect to the characteristic characteristics of the profile. wavy. In particular, the corrugation profile of the distributor channels has a branch angle which is less than 45 ° and is in particular in the range of approximately 5 ° to approximately 25 °. There can even be a sudden transition as well as a continuous transition in the construction of the profile between the profile of the distributor and the corrugated profile in the other areas of the plates. The distribution channels assume here the task of a distribution as uniform as possible of the fluid flow over the entire width of the plate. This improves the efficiency of the heat transfer, since in this case a larger heat exchange surface is actually used for the exchange. Also to improve the distribution of the medium through the entire surface of the heat exchanger, circulation channels can surround the elevated areas. The flow channels are preferably formed by means of a free section of corrugated profiles, which in particular surround the ring-shaped raised area. This thus forms a section with lower resistance to flow, in which several profiles open up, so that here also a function of distribution of the medium is fulfilled. It corresponds to a simple and inexpensive embodiment of the heat exchanger according to the invention when it is produced from a sequence of plates. Here the plates on either side of each other have different profiles relative to their corrugated profiles. A heat exchanger can in particular consist of a stack of those shaped plates identical to each other. It is then with this especially possible that the adjacent plates are rotated 1 80 degrees, the axis of rotation extending perpendicularly to the plane of the plates. This type of plate stacking is particularly advantageous when the perforations associated with the inlet conduits are formed in elevated areas and two different conduit guides must be assigned alternately to these. For this, the elevations in the area of the entrance ducts can essentially be formed in the manner of a dome in the form of a truncated cone. An alternative to these are dome-shaped elevations that present an optical cross-section. The plates can be formed identical to each other, corresponding to each other or similar or different. The plates identical to each other have identical properties with respect to their characteristics of the corrugated profile as well as the conformation of the corrugated profile. same as yes, but it is possible that the plates present different angles in their branches. The plates corresponding to one another preferably have a different conformation to one another of the corrugated profile and / or different values of the characteristic magnitudes, however with regard to the conformation of the edge as well as the conformation of its front and rear sides, those plates correspond each. The alternate use of for example two plates corresponding to each other, which differ mainly by means of different magnitudes characteristic of the angle of the branch, has the advantage that the position and the relative positioning of the contact zones of the plates can be easily optimized between yes in the profiled area in view of the necessary rigidity and the required flow.

The connection between the plates is especially produced by means of brazing. In order to achieve a good sealing effect in the area of the edge of the plates and simultaneously a stable construction of the heat exchanger, the plates can be provided with an elbowed edge whose height is selected in such a way that the plates adjacent to each other rest one on the other. another and overlap. The number of plates that overlap in the edge area can be up to five.

The larger the number, the more rigid the walls that enclose the heat exchanger. This at the same time promotes that the plates close in a permanently stable, resistant and fluid-tight manner. Other preferred configurations foresee that the corrugated profile extends to the edge and especially to the entire width thereof.

Here, in forming the corrugated profile, it should be considered that the plates still remain stackable, which happens when the course of the corrugated profile in the edge region is determined according to the mounting position of two adjacent plates. The wavy profile extends to the edge, when the wavy profile ends in the root zone of the bend, so that the profile is introduced in all its depth at the edge. Especially for technical reasons of production it can be advantageous when the root of the edge is in a zone free of corrugated profiles, since then the bending of the edge can occur in a zone not reinforced by the profile. The preferred embodiments then provide that the channel formed between the edge and the area of the corrugated profile is as narrow as possible. In particular, it is selected so narrow that when soldering a welding flow is introduced that fills or almost fills that channel in such a way that only a negligible amount of medium flows through the channel. The gutter must be formed in such a way that it does not serve as a diversion channel for the medium and an essential quantity of medium flows through the gutter instead of the area of the corrugated profile. In order to improve the stability of the heat exchanger outwards as well as to simplify the connection of external input ducts and external outlet ducts for the cooling medium and the working medium, it can be provided that at least on one front side of the heat exchanger a non-profiled external connection plate is placed. This non-profiled external connection plate here has flanges as connection points in particular. The connection plates can in particular have a greater thickness of material than the other plates and thus in particular represent a reinforcement and stabilization element, which on the front sides forms a housing part that closes outwards. The side walls of the housing that surround the exchanger on the outside are formed on the edge bordering the plates and overlapping with the plates adjacent to the edge. The edges are thus joined together fluid-tight, which can take place in particular by means of brazing. One possibility of characterizing the flow capacity through a plate stack is based on the determination of the hydraulic diameter between two neighboring plates along the main flow direction of the medium. The hydraulic diameter represents a ratio between the cross section through which the flow passes and the heat exchange surface. The hydraulic diameter hS is defined here as four times the proportion obtained from the surface fraction FV to the surface density Fd. The surface ratio Fv is determined as the ratio between the free cross section of the channel fK and the total frontal surface S of the channel between two neighboring plates, the density Fd is obtained from the ratio between the heat transfer surface wF to the volume of the block ue V. Therefore it applies: ? According to a preferred embodiment of the invention, the hydraulic diameter must remain as constant as possible along the entire flow direction of the medium. For this, under certain circumstances, an improved and eventually uniform flow capacity of the intermediate space between the plates forming the channel is obtained. According to another preferred embodiment of the invention the hydraulic diameter and especially when using the heat exchanger as an oil cooler, it is between 1 .1 mm and 2 mm. The preferred values for the hydraulic diameter is approximately 1.4 mm. Here the deviation of the hydraulic diameter during the profiling period of a pair of plates should not be greater than about 10%, especially it should be less than 5%. Obviously, the selection of the hydraulic diameter also depends on the media flowing in the intermediate spaces formed between the plates. The mentioned values are applied to an oil cooler in which in the heat exchanger water flows on the one hand and oil on the other side. According to a preferred embodiment, the contact points between two adjacent plates of the heat exchanger are evenly distributed over the entire surface of the plates. Preferably the points of contact between two neighboring plates have a surface density of 4 to 7 per cm 2, especially preferably 4 to 6 per cm 2. In such a conformation, sufficient rigidity of the heat exchanger is possible without the loss of pressure being excessively increased. The heat exchanger according to the invention can be used on the one hand as oil coolers, but also as evaporators or condensers. Here the cooling circuit of such a device can not only acclimate the interior space (of a vehicle), but also to cool heat sources such as electrical consumers, energy stores and sources of voltage or air charge. a turbocharger The heat exchanger is a condenser, when for example it is made by condensing the cold medium in an air conditioning installation with a compact heat exchanger operating with cooling medium and the refrigerant transfers the heat in the heat exchanger to the air that works as another means. The evaporation or condensation of another medium in a heat exchanger according to the invention can for example be carried out in applications in fuel cell systems. In these applications as a condenser or evaporator, it is desirable to use a powerful but compact heat exchanger, in which the refrigerant as the second medium absorbs or expels heat. Here, due to the very high internal purity requirements on the cold medium side, stamped turbulence formers can not be used, by means of which the cold medium circuit is contaminated with aluminum particles. In addition to these requirements for purity, an optimum distribution of the fluid at the inlet is also necessary, which finally evaporates or condenses in the heat exchanger. Ideally the fluid that during evaporation is mainly in liquid form at the inlet, and during condensation is in the form of. steam, is distributed over the entire width of the plate. A particularity of evaporation and condensation is the reduced temperature difference between both fluids. In the case of an optimum transverse distribution of the liquid fluid to be evaporated or of the gaseous fluid to be condensed, high power losses can quickly occur. The heat exchangers according to the invention offer solutions to these problems. The method according to the invention for producing a heat exchanger, in particular a heat exchanger according to the invention, provides for the corrugation profile to be produced by stamping the plates, then a special stacking of the plate is carried out. the plates and then the union by means of brazing. According to a preferred embodiment, the plates are stacked with each other in such a way that each two adjacent plates are rotated by 1 80 degrees with respect to each other. The bonding of the plates by means of brazing is carried out here especially in such a way that the edges of the plates are closely connected to one another and in particular the joining of adjacent plates at the contact points of the profiles is carried out simultaneously. With this an advantageous construction of a stable and union resistant element is obtained.

BRIEF DESCRIPTION OF THE FIGURES The invention will be described in detail below with the help of the embodiment shown in the drawings. In which: Figures 1 a, 1 b: shows the front side and the back side of a plate according to the invention; Figure 2: shows a view of a stack of those plates; Figure 3: shows a sectional representation of several plates stacked one on top of the other in the edge region; • Figure 4: shows an enlarged representation of the formation of distributor channels in the area of the perforations; Figure 5: shows a schematic representation of a connection plate with connection flanges; Figure 6: shows the flow of fluid through the plates, when one of the fluids flows through all the intermediate spaces between the plates; Figures 7a-7d: shows the effect of gravity on fluid distribution; Figure 8: shows the hydraulic diameter through a period of the corrugated profile in the main flow direction of the medium in the interspace between two plates; Figure 8a: shows a view on a plate of a heat exchanger; Figure 8b: shows the hydraulic diameter in the main flow direction of the medium in the interspace between two plates; Figure 9: shows a section of a heat transfer plate; Figure 10: shows a plate of a heat exchanger; Figure 1 1 a, b: a cross section in section of a heat exchanger.

DESCRIPTION OF THE INVENTION Figures 1a and 1b show the representation of the front side .and the back side of a plate according to the invention, while figure 2 shows a stack formed with plates according to figures 1. a and b. A plate 1 0 has a base body 1 1, which on its front and rear side is provided with a corrugated profile 12, which was formed by stamping the base body 1 1. In the embodiment shown in FIGS. 1 a and 1 b the corrugated profile 12 of the rear side according to FIG. 1 b corresponds to the negative profile of the front side according to the representation in FIG. 1 a. Thus, the corrugated profile 12 is formed by branches 10 that form a branch angle 13 between them, which have a fixed branch length 1 5 and enclose an area of undulations 1 6 between them. The wave profile extends transversely through of the plate 1 0. Along the length of the plate 10 are formed a plurality of corrugated profiles 12, the profiles being undulated at a close distance to each other and aligned with each other. In the plate 10 there is a peripheral edge 17 angled, which laterally limits the plate. Here the wavy profile 12 extends to the edge. The corrugated profile 12 can be formed on the plate 10 by means of stamping. The embossing can be performed in such a way that both sides of the plate 10 have corrugated profiles different from each other, in particular the corrugated profile 12 on one side can be the negative of the corrugated profile 12 on the other side, as this is clearly seen in the example of embodiment according to figures 1 a and 1 b. It is also possible for the plate 1 0 on both sides to have the same corrugated profile 12. Both times the corrugated profiles can be provided aligned with each other or displaced from each other on both sides of a plate. The corrugated profile 12 is characterized above all in the transverse section! because it presents the back part of the undulation that forms a flat area, which extend parallel to the plane of the plate. The flat area preferably has a width between 0.1 mm and 0.4 mm. In the corners the plate has a perforation 1 8, which passes through the plate perpendicular to its extension plane. Two of the perforations are here applied in a raised area.1 9. One of the perforations serves here for feeding the working medium in the area between two plates, while the other perforation, which is especially diametrically opposite, serves to expel the work medium. Another pair of perforations serves for the entry and exit of the cooling medium. If the plates 1 0 are stacked together as shown in Figure 2, then alternately the conduits for the working medium or for the cooling medium are fluidly connected with the intermediate space 20 between two plates 10, since the raised zone 19 supports the corresponding perforations 18 on the adjacent plate 1 0. The perforations thus through the stack of plates 21, form the inlet and outlet conduits for the cooling medium and the working medium. Figure 2 shows a perspective representation of a stack 21 of plates 1 0 according to figures 1 a and 1 b. In Figure 3 a sectional representation is shown through a stack 21 according to Figure 2. The plates 10 are stacked side by side and one on top of the other. The plates adjacent to the angled edge 17 lie next to one another and in such a way that the edge covers several plates. To achieve a fluid-tight connection between the edge 17 of two adjacent plates, they are joined together by means of brazing. Thus two plates adjacent to each other meet in different areas of their corrugated profile 12. Also in these areas the plates are joined together by means of brazing. To produce the joints by welding, the plates can be coated on one side or on both sides with a flux. Between two adjacent plates 1 0 an intermediate space 20 is formed, and in the intermediate space flows a current either of working medium or of cooling medium. The stack of plates is constructed in such a way that in the intermediate space 20 the working medium and the cooling medium flow alternately, so that in each plate 10 on the one hand the cooling medium flows and on the other side the working medium flows. . With this, an exchange of heat between the cooling medium and the working medium can be obtained through each plate 1 0. Since the plates have a corrugated profile in a plurality of places in the intermediate space 20 there is a different width of passage. The constant changes in the direction of the fluid in the channel, and the eddies that form in the open corrugated channel, destroy the limiting layer that is formed. This leads to a better heat transfer compared to a smooth channel. This promotes the exchange between both media through a plate 10. Furthermore, by means of forming the plates 10, it is achieved that a straight linear current from the supply conduit to the discharge conduit is not possible. Depending on the viscosity of the medium, the construction of the intermediate space 20 can lead to wholly or partially turbulent currents and thus a better heat exchange between the working medium and the cooling medium is obtained. Thus, by advancing the corrugated profile 12 transversely to the extension of the plate 1 0, the width of the plate 1 0 is also led to the corresponding medium, in such a way that the use of the heat exchange surface is improved. offers plate 1 0, which improves the efficiency of this heat exchanger. An essential element for the current can be considered that between two adjacent plates 1 or a Dalton grid causes contact zones, which act as impediments or points of deviation of the current. Furthermore, these contact areas serve as support for the plates with respect to each other and thus have a stabilizing function for the plates 10, in particular as regards the behavior during the fixing of the plates 10. In order to obtain a uniform value of the hydraulic diameter between two plates, as shown in figure 8, it is important to place the contact areas in the profiles of adjacent plates. These are formed from the corrugated profiles of adjacent sides of the plates as well as from the courses of the profiles. A uniform hydraulic diameter surely produces a uniform flow of the fluid through a wavy profile and over the entire width of the intermediate zone between the plates. By means of the constructive selection of the corrugated profile, the optimum hydraulic diameter is obtained for the final use that is intended for it. Figure 4 shows an enlarged representation of a plate 10 with a corrugated profile 12, which is formed by means of branches 14, which have a branch angle of 45 ° between them. The plate 10 is limited by means of an angled edge 17, the corrugated profile 12 extending to the area of the edge 17. In this figure, the raised area 19 formed between two perforations 1 8 is especially shown, of which one has the shape of dome. In the area between both bores ld, which in particular also extends in the area between the perforations 1 8 and the edge 17 which is close to it, distribution channels 22 are formed. The distribution channels 22 are also formed by means of a corrugated profile 23, which differs from the corrugated profile 12 in the remaining area of the plate 10, with respect to the angle and length of the branch. The angles of the branches have a value less than 45 °. The distribution channels 22, in particular in the area of the perforations, which are not made in the raised area 1 9, lead the medium entering the corresponding intermediate space transverse to the main extension of the plate 10 and thus produce a distribution uniform fluid flow over the entire surface of the plate. The raised area 19, in which the other perforation 19 has been made, is especially close to the perforation area of the plate 10 which is located above the stack and can be connected to it by means of brazing. Here a fluid-tight connection is formed between the intermediate space 20 and the plate above it, so that between that perforation and the intermediate space there can be no flow of the medium and the medium flowing through that perforation. 8 can first enter the next intermediate space 20 that is behind the plate 10 that is above. The perforations 1 8 for increasing their cross section can be formed in the form of a longitudinal hole, the longitudinal axis of the hole preferably extending in a direction transverse to the main flow direction H.

In addition, as shown in FIG. 4a, an unprimed annular zone 99 extending around a raised area 1 9 in the form of a dome can form a channel, which joins together several corrugated profiles 23 and several distribution channels 22. and promotes a good transversal distribution of the medium, since it forms an area that opposes little resistance to flow. The annular area 1 9 has a depth of embossing which in essence corresponds to the depth of embossing of the corrugated profile 23. Figure 5 shows a top view of the representation of a connection plate 24, which has four connection flanges 25 , which are aligned with the perforations 1 8 of the plates 10 of a stack of plates 21. A connection plate of this type can be placed on one or two sides of the stack and can be closed outwards. The connecting plate 24 at least on the outer side does not have a corrugated profile 12. If a connection plate 24 is placed on both sides of the plate stack, then it is possible for one of the two plates to have four connection flanges 25, but also a plate has two or three connection flanges 25, and the plate in front presents the remaining number of the four connection flanges 25. The connection flanges are associated with connection perforations. The connection flanges 25 serve to connect external conduits for the supply and discharge of working medium and cooling medium. Thus, the connection plate 24 reinforces the stack of plates 21 and forms a front wall of the housing. For this, the connection plate 24 can have an edge 17, which is adapted to the edge 17 of the plates 1 0.

The edges 17 of the plates located one above the other, in a stack of plates 21, as shown in Figure 2, form the walls of the housing of the heat exchanger. A stack of plates according to FIG. 2 provided with connection flanges 25 and a connection plate 24 thus form a heat exchanger. Such a heat exchanger can in particular serve as an oil cooler in a vehicle. Figure 6 shows a stack of plates 21, consisting of a base plate 88, of plates 1 0 and of a cover plate 89, which has three perforations 18, 18a. The perforations 18 serve to drive a first medium, which is conducted in such a manner through the plates flowing in a parallel manner through intermediate spaces between the plates 20. Through the perforation 18a a second means enters the stack of plates, means that comes out again from the stack of plates through the perforation in the base plate. Through a dividing wall that is between the perforations 1 8 a and 1 8b and that can not be observed from the outside, the flow channels can be divided for the second medium in at least two flow paths which present sequential flows and which consist of of several flow channels. The flow channels for the first medium on the other hand have parallel flows. In a different embodiment, the flow channels for the first medium are likewise divided into at least two flow paths, and have sequential flows. Figures 7a to 7d show different conformations of the main flow direction H of the intermediate space between the plates 20 in relation to the direction of gravity G at the place of assembly of the heat exchanger, as well as the advantageous influence on the distribution of the medium in the intermediate space of the plates especially when using it as a capacitor. Figures 7a and 7c show the use case of an evaporator. From Figures 7a and 7c it is noted that the main flow direction H must be transverse or antiparallel to the gravitational direction G, depending on its the longer side L or the narrower side s of the plates is directed in the direction of gravitation G, in the case that it is a liquid medium. By means of gravitation, a transversal distribution of the medium is promoted with respect to the main direction of flow. On the contrary, figures 7b and 7d show that a gaseous medium is distributed better between the plates 10, when the gravitational direction G counteracts the distribution of the medium between the plates. Figure 8 shows the hydraulic diameter through a total corrugated profile in the main flow direction, and in Figure 8a the shape of the corrugated profile 23 is shown with 1 0 plates adjacent to the contact points which are represented as circles. It is noted that the wavy profile moves through the entire period of the pattern that is formed by the wavy profile 23 of the adjacent plates, in a bandwidth of between 1.2 and 1.6 and on average amounts to about 1. Four. The shape of the corrugated profile is preferably selected in such a way that a hydraulic diameter is obtained in the main flow direction as constant as possible.

In Figure 8a the contact points of adjacent plates of the heat exchanger in a top view on the plates are represented as circles. It can be clearly recognized that the contact points are evenly distributed over the surface of the plates. A preferred surface density of the contact points to produce a sufficient stiffness is 4 to 7 per cm 2, especially 5 to 6 per cm 2 is preferred. This is illustrated in Figures 8b, 8c. Figure 8b shows the hydraulic diameter h D of a flow channel between two plates through several periods of the profile, or this is again in the main flow direction H of the medium. A higher surface density of the contact points would produce a course as represented by the dotted curve in Figure 8b, since many points of contact seen in the main flow direction H limit the cross section of the flow channel. This is made clear by interruptions 40 in the hydraulic diameter. By means of the shaping according to the invention, in particular by uniformly distributing the contact points, these interruptions are eliminated or reduced, in such a way that a hydraulic diameter with a constant course is produced. The fewer such interruptions in a flow-channel, the less narrowing the channel will present to the flowing medium, this means that pressure losses can be reduced in the case of equal surface densities of contact points. A uniform distribution is achieved in particular when a corrugated area between two particularly straight branches of a corrugated profile of a plate does not exactly coincide with the corrugated area of the adjacent plate. Under certain conditions it is much more advantageous when the corrugated areas of adjacent plates, seen in the main flow direction, are displaced from each other in such a way that each corrugated area is flanked transversely to the main flow direction by two contact points of both plates, which advantageously have a distance equal or similar to each other as to the other points of contact and with this between them allow a passage of the current, which allows a considerable current flow and with this do not contribute considerably to a loss of pressure of the flow channel formed between the plates. The distance between two points of contact on the other hand should also not be selected too large since then under certain circumstances local weaknesses could form in the stability of the heat exchanger. Figure 8c shows the behavior of the stability F and the pressure loss DV of a heat exchanger on the density BD of the contact points between two plates. The stability of the heat exchanger increases linearly with the density of the contact points BD and precipitates as a straight line 42 as seen in Figure 8c. Contrary to this, the loss of pressure DV in this representation (42) presents an advance; so that the proportion F / DV of stability F to loss of pressure DV has a maximum of 43 with a density of contact points BD1. If the pressure loss according to the invention is reduced (44), then the aforementioned maximum rises (.45) and eventually moves to a higher contact point density BD2. Experimentally it has been shown that a density of contact points of 4 to 7 per cm 2, preferably 5 to 6 per cm 2, leads to good stability with pressure losses considered acceptable. Seen in another way, as shown in Figure 8c with the arrow 46, in the case of a constant pressure loss DV can be passed to a higher density of the contact points which leads to a greater stability dF of the heat exchanger F. Figure 9 shows a section of a plate 30 of a heat exchanger. The junction points between two neighboring plates are shown by crossing points of the corrugated profiles in question of both plates. To obtain that a distance between the edge of the plates and the crossing points near the edges is not so great, it is under certain circumstances advantageous to modify the geometry of the outermost branch in comparison with the internal branches of the corrugated profile. In the case of the plate of figure 9 for this reason, the branch angle 2b of the external branch 31 of the branch angle 2a of the internal branch 32 is differentiated. As can be seen in figure 9, the half of the branch angle b in an edge area of the plate 30 is for example 60 ° and in the measured area of the plate half the angle of the branch is 45 °. With this in the edge areas 33 of the plates a more uniform distribution of the junction points is obtained and with this a ter resistance to the pressure of the heat exchanger. Figure 1 0 shows a plate 35 of a heat exchanger, extending in the corrugated profile 34 to the angled plate edge 36, where the remaining channel 37, which under certain circumstances allows unwanted bypass flows, presents a section very small cross section, so that the bypass current can be reduced. Especially in the case of a welded heat exchanger, that is when the plate 35 is plated with welding, between the outermost branches 48 of the corrugated profile 34 and the angled plate 36 weld menisci are formed, which reduce the channel edge 37 or preferably close it. To produce a reduction of the depression caused by the heat exchanger, the interruptions 38 of the plate and with this the cross sections of the collecting channels formed are enlarged oval. Figure 1 1 a shows a cross section of a plate 41 of a heat exchanger 42, which is formed of several plates 41, as shown in Figure 1 1 b, The plates 41 present as feed and discharge conduits, they present a pair of perforations 43 perpendicular to the plane of the plates, the perforations 43 being raised in comparison with the base plane of the plate in question 41 in such a way that a fluid bond is formed alternately from one of the two perforations to the second space intermediate between the plates 44. As shown in Figure 1 1 b, the raised perforation 43 is in a non-elevated area of the plate 41, such that the height of the raised area for example is as large as the height of a corrugated profile of the plate 41. Figure 12a shows a cross section of a plate 51 of a heat exchanger 52, which is formed of several plates 51, as shown in Figure 12b. The plates 51 as feeding and discharge conduits each have a pair of perforations 53 perpendicular to the plane of the plates, the perforations 53 being raised in comparison with the base plane of the plate in question 51 in such a way that a bond is formed by fluid alternately from one of the two perforations to the second intermediate space between the plates 54. As shown in Figure 12b, the raised perforation 53 is in an elevated perforation of the plate 51, such that the height of the zone For example, it is only half the height of the corrugated profile of the plate 51. By means of this construction, the circumstances in which the material is thinned when producing the raised areas are reduced, so that at least in those areas advantageously improves the tensile strength, that is the resistance to the internal pressure of the heat exchanger 52.

Claims (32)

1. CLAIMS 1 . A heat exchanger, in particular an oil cooler for motor vehicles, is formed by plates joined together, between the plates there are formed hollow spaces which are closed outwards, in which alternately a first and a second medium flows means through at least one supply conduit and a discharge conduit, wherein the plates are profiled in such a way that between the profiles of the plates are formed contact zones in which contact the plates are joined together, characterized because the profiles of the plates (10) and their points of contact are constructed in such a way that the current formed from the first or second means, which is formed between the plates from the corresponding supply conduit to the corresponding discharge conduit, it does not follow a straight line.
2. 2. The heat exchanger according to the claim 1, characterized in that the plates (19) have a wavy profile (12) which is repeated, which essentially extends transversely to the main flow direction (H) and is especially wavy in a zigzag pattern around the direction forward.
3. The heat exchanger according to one of the preceding claims, characterized in that the corrugated profile (12) between the corrugated area has branches (14) extending in a straight line, the course of the corrugated profile being characterized by means of the length of the branches, the angle formed between the branches and the depth of the profile of the undulations.
4. The heat exchanger according to one of the preceding claims, characterized in that the formation of the corrugated profile is characterized by the progress of the profile in the region of the branch and the corrugations, the adjacent profiles being repeated in a predetermined division.
5. The heat exchanger according to one of the preceding claims, characterized in that the corrugated profile on the outside of the rear part of the wave has a flat region.
6. The heat exchanger according to one of the preceding claims, characterized in that the flat region of the corrugated profile in the cross section of the corrugated profile has dimensions between 0.1 mm and 0.4 mm.
7. 7. The heat exchanger according to one of the preceding claims, characterized in that the angle of the branches (13) is preferably between 45 ° and 1 35 °, preferably 90 °.
8. The heat exchanger according to one of the preceding claims, characterized in that the depth of the profiles is between 0.3 mm and 2 mm, in the case of liquid media, preferably between 0.5 mm and 1 mm and in particular between 0.7 and 0.8 mm and in the case of gaseous media, preferably in the range between 0.6 mm and 2 mm and in particular is 1.5 mm.
9. The heat exchanger according to one of the preceding claims, characterized in that the length of the branch (15) is in the range of 8 to 1 5 mm and especially in the range of 9 mm to 12 mm.
10. The heat exchanger according to one of the preceding claims, characterized in that the corrugated profile (12) is formed on the plate (10) by means of stamping, the plates (10) being preferably produced from a metallic material, in particular aluminum, the plates being preferably coated when less on one side with an auxiliary material for welding. eleven .
11. The heat exchanger according to one of the preceding claims, characterized in that the plates (1 0) as supply and discharge conduits have a pair of perforations (18) extending perpendicular to the plane of the plates, the perforations (1) 8) raised with respect to the flat surface in such a way that a fluid bond alternately forms from both perforations to each second intermediate space between the plates (20). 1 2.
12. The heat exchanger according to one of the preceding claims, characterized in that the raised area of at least a part of the perforations is surrounded by a peripheral peripheral zone free of corrugation.
13. The heat exchanger according to one of the preceding claims, characterized in that in the region of the perforations (18) associated with the supply conduits, distribution channels (23) are provided, which are preferably formed by means of a corrugated profile (12) with a branch angle, which is greater in comparison with the branch angle of the corrugated profile.
14. 14. The heat exchanger according to one of the preceding claims, characterized in that the perforations associated with the supply conduits are oval, elliptical or rectangular.
15. The heat exchanger according to one of the preceding claims, characterized in that two plates (1 0) different from each other are used in relation to the corrugated profile (12), in which the corrugated profiles (12) differ at least as far as they are concerned. with respect to the characteristics of branch length (1 5), branch angle (13) and profile depth.
16. The heat exchanger according to one of the preceding claims, characterized in that the corrugated profile (12) on one side of the plate (1 9) differs from the corrugated profile (12) on the other side of the plate (10) when less, it is related to one of the characteristics of the length of the branch (15), angle of the branch (13) and depth of the profile.
17. 17. The heat exchanger according to one of the preceding claims, characterized in that the corrugated profiles of adjacent plates are identical to each other.
18. The heat exchanger according to one of the preceding claims, characterized in that the heat exchanger is formed by a stack (21) of plates (10), wherein the plates (19) are placed alternately rotated together in 1 80 °.
19. The heat exchanger according to one of the preceding claims, characterized in that the plates (10) have an elbow edge (17), and the plates adjacent to the edges (17) are placed next to one another and are joined together each other by means of brazing.
20. 20. The heat exchanger according to one of the preceding claims, characterized in that the elbow edge (17) covers several plates (10), especially up to five. twenty-one .
21. The heat exchanger according to one of the preceding claims, characterized in that the corrugated profile (12) extends to the edge (17), in particular extends beyond the edge (1 7).
22. The heat exchanger according to one of the preceding claims, characterized in that between the ends of the corrugated profile and the edge of a profile-free bent section, the width of which is less than 2 mm and is preferably formed in such a way that welding the plates the bending zone of the crest sections of the corrugations the weld is placed in such a way that a passage of the medium towards the flexed section is reduced or essentially avoided.
23. The heat exchanger according to one of the preceding claims, characterized in that at least one connection plate (24) is placed at least on the front side of the heat exchanger, which at least on the outer side has no profiling, which has points connection (25) for the first and second means, which flow into the connection conduits and are aligned with the perforations (1 8).
24. 24. The heat exchanger according to one of the preceding claims, characterized in that the hydraulic diameter (hD) in the main extension direction (D) has a variation with respect to the average value of maximum 25%, especially maximum 15 % and preferably maximum 10%.
25. The heat exchanger according to one of the preceding claims, characterized in that the hydraulic diameter (hD) has an average value between 1 mm and 4 mm, being in the case of liquid media between 1 mm and 2 mm and preferably around of 1.4 mm, and in the case of gaseous media, preferably 3 mm.
26. 26. The heat exchanger according to one of the preceding claims, characterized in that the contact points between two plates adjacent to each other are evenly distributed on the surface of the plates.
27. The heat exchanger according to one of the preceding claims, characterized in that the contact points between two plates adjacent to each other, have a surface density of between 4 to 7 per cm2, especially of 5 to 6 per cm2.
28. 28. The heat exchanger according to one of the preceding claims, characterized in that a phase transition of a medium takes place in the intermediate space between the plates.
29. 29. The heat exchanger according to one of the preceding claims, characterized in that the mounting position of the heat exchanger is determined in such a way that the transverse distribution of the medium in the intermediate spaces between the plates rests on gravity.
30. 30. A procedure to produce a spice heat exchanger! according to one of the preceding claims, characterized in that the method in particular includes the steps of printing the plates (1 9), stacking the plates (10) together and fixing them together, preferably by means of brazing.
31. 31 The method according to claim 30, characterized in that the stacking of the plates with each other is carried out in such a way that two adjacent plates (0) are rotated 180 g to each other.
32. 32. The method according to claim 30 or 31, characterized in that the brazing is carried out in such a way that the plates (10) are hermetically joined to one another at their edges, whereby the joining of the plates is preferably carried out simultaneously. adjacent plates (10) at the contact points of the corrugated profiles (12). RES UMEN The present invention relates to a heat exchanger, such as that which is especially used in vehicles as an oil cooler, as well as a process for its production. A heat exchanger, which is especially used as an oil cooler in motor vehicles, is formed by means of plates joined together. Between the plates, hollow spaces are closed closed outwards. The hollow spaces through feed and discharge conduits alternately receive a first medium or a second medium, and the corresponding medium flows through those hollow spaces. The plates are profiled in such a way that contact zones appear between the profiled plates. In the region of these contact areas the plates are joined together. The plates being formed in such a way that the current of the first or second medium formed between the plates, from the corresponding supply conduit to the corresponding discharge conduit, does not follow a straight line.