FR2795167A1 - PLATE HEAT EXCHANGER, ESPECIALLY FOR COOLING A MOTOR VEHICLE OIL - Google Patents

Abstract

A heat exchanger comprises a multiplicity of stacked plates (10) which are identical to each other and have the general shape of a square and which are provided with raised peripheral edges (14) assembled in a sealed manner to define between the plates of the first channels flow channels for a first fluid (F1) which alternate with second flow channels for a second fluid (F2). The exchanger further comprises an inlet (26) and an outlet (28) for the first fluid (F1) which are located on a diagonal of the square, as well as an inlet (30) and an outlet (32) for the second. fluid (F2) which lie on another diagonal of the square. The heat exchanger can in particular constitute an oil cooler for a motor vehicle.

Description

J I

  Plate heat exchanger. in particular for cooling an oil in a motor vehicle The invention relates to heat exchangers, in particular

for motor vehicles.

  It relates more particularly to a heat exchanger comprising a multiplicity of stacked plates each provided with a raised peripheral edge, and in which said peripheral edges are tightly assembled to delimit between the plates first flow channels for a first fluid which alternate with second flow channels for a second fluid, the exchanger further comprising an inlet and an outlet for the first fluid thus

  than an inlet and an outlet for the second fluid.

  A heat exchanger of this type, also called a "plate exchanger", or "plate exchanger", is known in particular from the publication DE-A-195 11 991. Such a heat exchanger is used for example in as a cooler

  motor vehicle oil to cool

  the engine oil or the cooling of the automatic gearbox oil, by heat exchange with a coolant, usually

  the one used to cool the vehicle engine.

  In a heat exchanger of this type, the plates are

  usually made by stamping a metal sheet

  that, and are stacked, so that their respective peripheral edges fit into each other and are then brazed together to ensure sealing, which

  used to define fluid circulation channels.

  The heat exchanger thus results from a stack of plates

and does not require a housing.

  An inlet pipe and an outlet pipe are then provided for a first fluid which communicate with a first series of channels, as well as an inlet pipe and

ÀX 2

  an outlet for a second fluid which communicate with a second series of channels, so that the channels of the first series alternate with the channels of the second series. The plates have openings located to the right of the aforementioned pipes and alternately sealed, either by stampings or by added rings, to

  ensure or prohibit the passage of one or the other fluid.

  In known heat exchangers of this type, plates of two different types are usually provided which are arranged alternately, which increases in particular the costs.

in material and tools.

  These plates have a generally flat bottom and it is

  provided, in each flow channel, a disturbing element

  tor to promote a turbulent flow of the fluid and therefore

heat exchange.

  In addition, it is generally necessary to provide different disturbing elements for the first fluid and the second fluid, which further complicates the manufacture of

the heat exchanger.

  Thus, all of these known heat exchangers require a

  large number of parts of different types to assemble.

  The object of the invention is in particular to overcome the drawbacks

mentioned above.

  Its main purpose is to provide a plate heat exchanger of the type defined above, which comprises a minimum number of parts of different types, and in particular which

  is devoid of disturbing elements.

  The invention also aims to provide such a plate heat exchanger capable of improving the heat exchange between the two fluids, without increasing the pressure drop of the circuit of the first fluid and of the circuit of the second fluid. The invention proposes for this purpose a heat exchanger of the type defined in the introduction, in which the plates are identical to each other and have the general shape of a square, said plates each having a bottom having undulations defined by generators s' extending in a given direction, and these plates are arranged alternately by being rotated by 90 relative to the adjacent plate (s), so that each channel is delimited by corrugations crossed at 90, and in wherein the inlet and outlet of the first fluid are located substantially on a diagonal of the square, while the inlet and outlet of the second fluid are located substantially on another diagonal

of the square.

  Thus, the heat exchanger is formed from plates of a single type which reduces the number of types of parts and

  facilitates assembly operations.

  Three-dimensional channels of particular shape are thus defined, each delimited between two undulating bottoms, the respective undulations of which extend in directions.

  substantially perpendicular to each other.

  In addition, as the fluid inlets and outlets are available

  located on diagonals of the square, it is possible to superimpose

  serve one plate over another by rotating it

90.

  The undulations give a value for the hydraulic diameter

  determined and equal for the two fluids.

  It will be recalled that for such a three-dimensional channel, the hydraulic diameter is defined by the relation Dh = 4 X

  Volume occupied by the fluid / Wet surface.

  According to the invention, each channel has a hydraulic diameter

  that (Dh) of chosen value, defined by the relation Dh = 2.h, oh represents the height of the channel, that is to say half of the maximum spacing between the respective peaks of the undulations of a first plate and the respective ridges

  undulations of a second adjacent plate.

  It was found that when the value of the hydrau-

  liaue Dh is chosen and is between 1 and 3 mm, an optimal heat exchange is obtained between the two fluids, without increasing the pressure drop of either

these fluids.

  Advantageously, the value of the hydraulic diameter Dh is

substantially equal to 1.8 mm.

  In the invention, the undulations of two adjacent plates

  are preferably in mutual contact.

  The corrugations of the plates are advantageously shaped

substantially sinusoidal.

  According to another characteristic of the invention, the plates are formed by stamping a metal sheet, of

preferably based on aluminum.

  The raised edges of the plates are advantageously assembled

between them by brasaae.

  In a preferred application of the invention, the exchange

  heat gor is produced in the form of an oil cooler for a motor vehicle, in which one of the fluids is engine oil or oil of the automatic transmission of the vehicle, while the other fluid

is a cooling fluid.

  In the description which follows, made only by way of example

  ple, reference is made to the accompanying drawings, in which: - Figure 1 is a perspective view of a plate heat exchanger according to the invention; J 5 - Figure 2 is a partial sectional view of the heat exchanger of Figure 1; and - Figure 3 is a top view of the heat exchanger of Figure 1. The heat exchanger shown in Figure 1 comprises a multiplicity of plates 10, also called "half-blades", stacked in a direction assembly or stacking,

  according to an assembly technique called "scales".

  The plates 10 are here identical to each other and each have a bottom 12 surrounded by a peripheral edge 14 which is generally planar and raised upwards. The bottom 12 here has the shape of a square with rounded angles and it is provided with corrugations 16, of substantially sinusoidal shape, defined by generatrices parallel to each other and parallel to two opposite sides 18 of the square and therefore perpendicular to the

  two other opposite sides 20 of the square (Figures 1 and 3).

  The plates 10 are formed by stamping a sheet

  preferably aluminum based, which is advantageously

  well coated with solder plating on at least one

of its faces.

  To form the exchanger, the plates 10 are stacked and thus come into mutual contact at their periphery by their respective raised edges 14, which are brazed together to

  ensure a tight mechanical connection.

  The plates 10 are arranged alternately, each being rotated each 90 relative to the adjacent plate (s), so that the respective corrugations 16 of two adjacent plates are crossed at 90 (FIG. 2 ). Furthermore, the undulations of two adjacent plates 10 are

in contact with each other.

  The plates 10 thus delimit between them channels 22 for a first fluid F1 which alternate with channels 24

for a second fluid F2.

  The heat exchanger further comprises (FIG. 1) an inlet pipe 26 and an outlet pipe 28 for the first fluid F1, as well as an inlet pipe 30 and a

  outlet pipe 32 for the second fluid F2.

  The pipes 26 and 28 are on a diagonal of the square formed on the plate 10 located at one end of the stack and the pipes 30 and 32 are on another diagonal of this square (Figure 3). Tubing 26, 28, 30 and 32 are mounted respectively on four circular openings 34, 36, 38 and 40 of the upper plate of the stack (Figure 3). These openings all have the same diameter and are located equidistant from the center of the square. So when the plates are stacked, they can communicate with each other by

  four series of aligned openings.

  The pipes 26, 28, 30 and 32 extend inside the stack and means are provided for communicating the pipes 26 and 28 with the first channels 22, on the one hand, and the pipes 30 and 32 with the latter

  channels 24, on the other hand. These means of communication, in themselves

  even known, are not described. Details on this can be found in particular in Publication DE-A-195

11 991 cited above.

  The respective corrugations 16 of the plates 10 make it possible to give the channels 22 and 24 a particular three-dimensional structure which promotes turbulent flow of the fluid F1 and of the fluid F2 and, consequently, a good heat exchange between them. This eliminates the disturbing elements which, until now, had been considered necessary in this type of plate heat exchangers. The flow of fluids F1 and F2 in the channels takes place at 90 relative to the corrugations, as shown by the arrow

E for fluid f2 (Figure 3).

  In the invention, it is also essential that the diameter

  hydraulic channel 22 and 24 has a selected value.

  As a general rule, the hydraulic diameter is defined by the relationship Dh = 4 x Volume occupied by the fluid / Area

wet.

  Here, in the case of a thin channel, the hydraulic diameter Dh can be expressed, in a simplified way, by the following relation: Dh = 2 x h,

  where h represents the average height of the channel.

  Referring to Figure 2, h represents half of the maximum spacing between the respective peaks 40 and 42

  respective corrugations 16 of two adjacent plates 10.

  Here, the value of the hydraulic diameter Dh must be understood

  between 1 and 3 mm. Advantageously, this value is sensitive-

equal to 1.8 mm.

  The heat exchanger advantageously constitutes a cooling

  oil straightener. It can be used to cool engine oil or automatic transmission oil in a motor vehicle. In this case, one of the fluids is constituted by this oil, while the other fluid is constituted by a cooling fluid. The latter is advantageously the liquid which is usually used for

  motor vehicle engine cooling.

  When the heat exchanger is used to cool the engine oil, it is then fixed either directly on the engine block, or on a filtration unit connected directly to the engine. The exchanger can then be connected to the

  coolant circuit through conduits.

  In the case of automatic gearbox oil cooling, the heat exchanger can be connected directly to the gearbox oil pan. It has been found that such a heat exchanger allows an improvement in the heat exchange between the two fluids, without increasing the pressure drop in the oil circuit and the coolant circuit. Tests have shown that, compared to a conventional plate heat exchanger fitted with disturbers, the heat exchanger according to the invention releases a thermal power which can be higher by 15% and a pressure drop which can be

reduced by 30 to 40%.

  Of course, the invention is not limited to the embodiment described above by way of example but extends

also to other variants.

Claims (8)

Claims   1. Heat exchanger comprising a multiplicity of stacked plates (10) each provided with a raised peripheral edge (14), and in which said peripheral edges are assembled in leaktight manner to delimit between the plates of the first flow channels (22 ) for a first fluid (F1) which alternate with second flow channels (24) for a second fluid (F2), the exchanger further comprising an inlet (26) and an outlet (28) for the first fluid (F2) F1) as well as an inlet (30) and an outlet (32) for the second fluid (F2), characterized in that the plates (10) are identical to each other and have the general shape of a square, in that '' they each have a bottom (12) having corrugations (16) defined by generators extending in one direction   given, in that the plates (10) are arranged alternately   nance by being rotated 90 with respect to the adjacent plate (s), so that each channel (22; 24) is delimited by corrugations crossed at 90, and in that the inlet (26 ) and the outlet (28) of the first fluid (F1) are located substantially on a diagonal of the square, while the inlet (30) and the outlet (32) of the second fluid (F2) are   lie substantially on another diagonal of the square.   2. Heat exchanger according to claim 1, character-   rised in that each channel (22; 24) has a hydraulic diameter (Dh) of chosen value, defined by the relation   Dh = 2.h, where h represents the half-height of the channel, i.e.   say half the maximum spacing between the respective ridges (40, 42) of the respective undulations (16) of the   adjacent plates (10) delimiting the channel.   3. Heat exchanger according to claim 2, character-   rised in that the value of the hydraulic diameter Dh is between 1 and 3 mm.   4. Heat exchanger according to one of claims 2 and   3, characterized in that the value of the hydraulic diameter Dh is substantially equal to 1.8 mm.   5. Heat exchanger according to one of claims 1 to   4, characterized in that the corrugations (16) of two plates   (10) adjacent are in mutual contact.   6. Heat exchanger according to one of claims 1 to   5, characterized in that the corrugations (16) of the plates   (10) are substantially sinusoidal in shape.   7. Heat exchanger according to one of claims 1 to   6, characterized in that the plates (10) are formed by stamping a metal sheet, preferably based on aluminum.   S. Heat exchanger according to one of claims 1 to   7, characterized in that the raised edges (14) of the plates   (10) are joined together by brazing.   9. Heat exchanger according to one of claims 1 to   B, characterized in that one of the fluids is engine oil or the oil of an automatic gearbox of a motor vehicle, while the other fluid is a fluid cooling.