DE102005004284A1 - Heat exchanger/flat pipe vaporizer for a motor vehicle's air-conditioning facility has a sheet metal collecting tank divided lengthwise into two chambers - Google Patents

Abstract

A collecting tank (2) divides lengthwise into two chambers. Ends of pipes, e.g. flat pipes, are inserted into the base of the collecting tank, which has a tunnel-shaped collecting tank part, i.e. a level collecting tank part to form the base, and covers at each front side. An independent claim is also included for a motor vehicle's air-conditioning facility with a vaporizer.

Description

The The invention relates to a heat exchanger, in particular a flat tube evaporator for a motor vehicle air conditioner, according to the preamble of Claim 1.

From the DE 198 26 881 A1 is a heat exchanger, in particular an evaporator, known, in which a collection box is provided of sheet metal, which is formed from a prepared board.

The Board is made of an aluminum alloy, from which also the flat tubes, the corrugated ribs and the side parts and the other elements of the heat exchanger consist. She will first punched out of a plate, which is then shaped so that one level bottom (essentially flat collection box part) formed is, at the longitudinal edges bent parts (tunnel-shaped Collecting box parts). The bent parts are bent in a radius to a cylindrical surface, from the longitudinal edges in such a way are folded, that they rest parallel to each other and run substantially perpendicular to the ground. The longitudinal edges are with several, over her length arranged distributed tabs provided by recesses of the Bodens are inserted through and facing the flat tubes outside are caulked. In this way, a collection box with the two Chambers formed, which has a relatively high strength before a soldering he follows. The board is solder plated or with a solder coating Mistake.

In the floor are each passages provided in which the flat tubes are received. Each in the area of the longitudinal edges of the soil from which the parts are bent, the passages are dense used on the adjoining longitudinal edges. This results in a depth for the heat exchanger, the only minor greater than the sum of the depths of the flat tubes is. The longitudinal edges of the parts are aligned with each other Recesses provided in the side facing away from the supply and discharge side between the transverse wall and the end of the collection chamber are located. The transverse walls will be from the outside inserted into the chambers. There are slots in the parts for this or provided in the ground.

at the production of the header box, a flat board is first manufactured, especially by punching, in the required tabs and the later this Lugs receiving openings as well as recesses are punched. After that, first the Longitudinal edges of the Parts bent. Subsequently become the passages incorporated. If the partitions be inserted into the chambers from the ground in making the passages provided in the same operation, the passage-like slots for the partitions. If the partitions from the side into the chambers to be inserted, so Be the one for it required Slots already incorporated in the planar board. After finishing the passages the collection box is finished bending. Then the tabs are caulked.

In front the soldering with the flat tubes and the corrugated ribs and side panels provided heat exchanger be the front ends of the headers by means of inserted lid locked. The lids are made as a sheet metal stamping, the one according to the contour of the front ends of the collecting box circulating, imprinted Edge has. One of the covers has openings for connecting the Refrigerant supply and -Abführung on. The edge is provided in the region of the longitudinal edges with a transverse embossing, the sum of the wall thicknesses adapted to the longitudinal edges is. Due to the embossed Edge creates a step that attaches when attaching the lid the inner walls of the collecting tanks applies and a frictional Retaining compound forms. This frictional Retaining compound is supported by means of several tabs, which at the embossed edge connect and angled at 90 ° are. These tabs surround the collection boxes on the outside.

Furthermore have known evaporator in the standard standard rib densities (also at small rib heights) almost parallel ribs or a small opening angle between the individual ribs, due to Kapilfarkräften too an unfavorable Water retention behaviors, i. a lot of water due locally given geometry to save.

at Bad water drain tend to the evaporator may Spraying - before all at great Air volume and small faces - which in turn the permissible Rib density (number of rib sections per unit length in the longitudinal direction the tubes). The danger of splashing becomes greater, ever more condensate accumulates in the individual rib turns the lower the area which can be freely flowed through by the air.

One unfavorable Water storage and drainage behavior due to the given rib geometry have, for example, evaporator with almost parallel ribs or small opening angles between the individual rib sections. In particular, then the flow rate or Limits the amount of air to which a splash is still avoidable.

It Object of the invention to provide an improved heat exchanger available put. One object is in particular an improved water separation and / or a reduction in water storage capacity

These Task is solved through a heat exchanger with the features of claim 1 or claim 13. Advantageous Embodiments are the subject of the dependent claims.

According to the invention is a Heat exchanger provided, with at least one collecting box made of sheet metal, in the longitudinal direction is divided into at least two chambers and in the bottom of the Ends of tubes, in particular of flat tubes, are inserted, and the collector box a tunnel-shaped collection box part, one essentially flat collection box part that forms the ground, and each having a lid on the front side, wherein at least one lid at least in its outer edge area just trained and form-fitting is positioned in the collection box. Due to the level training of Lids enabled a simple production of the same by means of punching a sheet, as well as a simple fitting. The lids take up less space, compared with the conventional, deep-drawn lids, so that the heat exchanger builds smaller. Much more can for the closed end faces of the heat exchanger uses a sheet metal be at least substantially equal to the partition panels. The form-fitting Positioning in the collection box ensures optimal soldering.

Of the Lid is preferably introduced from the front side, wherein he collector box side rests on several stops on the tunnel-shaped collection box part and / or formed on the flat collection box part. On the outside the lid is preferably secured by means of a plurality of bent tabs, taking the tabs from the stops are spaced so that the lid as possible without play between them is included. The tabs can around a parallel to the longitudinal axis of the Be bent header tank axis. Alternatively, they can from the outside to be bent inwards. To ensure a secure soldering, the lid points a thickness, at least in the area in contact with the collecting box area, from about 1 to 2 mm, preferably 1.5 mm. Due to the positive positioning before soldering there is an improved lid tightness. In addition, can be increase process reliability, so that produces less faulty heat exchanger become.

The Tabs are preferably part of the tunnel-shaped collection box part and / or of the flat collection box part, passing through punched slots in the corresponding collection box part forming board in one piece with are formed of the same.

Of the Lid preferably has an opening in the case of a frontal refrigerant supply and / or -Abführung, its edge to the outside is bent. The opening is preferably circular designed, in particular as a passage, whereby also a different kind Training, in particular an oval training, the opening is possible, so the area the lid can be optimally utilized, with maximum flow area.

The opening is preferably formed conical, in particular with an angle of the Edge to the longitudinal axis the passage of maximum 5 °, more preferably from 2 ° to 3 °, so that ensures self-locking is.

Prefers a suction tube is provided which is attached to the lid with an opening is, which has an inner diameter, which is about the outer diameter of the opening narrowing edge corresponds, with the suction tube on the passage pushed. this makes possible a constant and slightly widening in the flow direction Flow cross-section, so that this largest possible and the refrigerant side Possible pressure drop can be kept low. This allows the evaporator performance increase.

One Injection tube, which is attached to the lid with an opening points preferably an outer diameter on, about the smallest inner diameter of the opening delimiting edge equivalent.

to Facilitation of insertion the lid has the edge of the header box plate for the lids preferably an insertion bevel, but this can be designed as a bevel but also rounded.

The two tunnel-shaped collection box parts preferably have a substantially semicircular shape, which has a positive effect on the strength properties of the header tank, so that the material thickness - compared to conventional headers - can be preferably reduced, in particular to wall thicknesses of about 0.8 mm at a Attachment of injection and suction pipe from one of the end faces (through two lids), or in the case of longitudinal attachment of the same via a connection flange in the area of the collecting tank of approx. 1 mm. By reducing the sheet thickness results in a material and weight savings, so that the manufacturing cost and the subsequent operating costs lowered who you can.

The used flat tubes preferably have a width of 2 to 3 mm on, making them narrower as conventional Flat tubes are formed.

Of the heat exchangers depends on of the block width 4 or more flooded, in particular 6-flow-through.

According to one Another aspect of the present invention includes a heat exchanger Flat tubes and corrugated ribs, wherein the corrugated fins have a rib height, which corresponds to the distance between two flat tubes, and wherein two each over a rib bow connected rib sections at an opening angle α inclined to each other are. At a rib height from 3 to 6 mm, preferably from 4 to 5 mm, and a rib density of 50 to 90 ribs, preferably from 60 to 80 ribs, more preferably 70 ribs, each 100 mm, results according to the present invention an enlarged angle between the individual ribs (with the same rib density and the same Radius of curvature). Because of this larger opening angle The ribs will have a smaller capillary action in the rib turns achieved, resulting in a better condensate drain behavior or a lower stored amount of water locally in the Rippenwindungen and thus also leads in the evaporator and possibly reduces the risk of splashing the evaporator. The opening angle at least two rib sections, preferably many or all rib sections, is preferably 22 ° +/- 7 ° or 30 ° +/- 10 °.

A further enlargement of the opening angle is under circumstances achievable if one or more ribbed arches at least partially a radius of curvature of less than 0.4 mm, preferably less than or equal to 0.35 mm, more preferably less than or equal to 0.3 mm. An advantage is a Width of the flat tubes of about 1.5 to 3 mm.

By a smaller rib height or a larger rib opening angle is reduced for capillary action in the rib turns, so that less condensate keeps in the rib turns. In order to connected are a lower storable amount of water and under Circumstances Better drainage and possibly a lower risk of Spraying. On the other hand leads a smaller rib height to a distribution of the condensate on more ribs and pipes (more Heat exchange surface), so that overall less condensate is incurred per rib turn. From this in turn results in a lower risk of splashing and under circumstances a cheaper one Run-off behavior along the tubes and / or the ribs.

indirect Benefits may be a higher one allowed Rib density and thus an increased Performance potential, a lower risk of bacterial growth and thus a reduced odor and optionally one Cost savings through easier surface treatment, which may even be completely eliminated. Furthermore is a reduction of a so-called flash fog danger (sudden Fogging of windshields due to moisture the evaporator) by faster drying of the evaporator surface possible.

One such heat exchanger is used in particular as a flat-tube evaporator for a motor vehicle air conditioning system uses.

in the The invention is described below with reference to an exemplary embodiment with reference explained in detail on the drawing. in the drawing show:

1 a perspective view of a collecting box,

2 a detailed view of the collecting tank of 1 .

3 the collection box of 1 before installation of the front-mounted cover,

4 a detailed view of 3 ,

5 a detailed view of the collecting tank of 1 , wherein the right of the two covers is not shown,

6 a 5 corresponding detail view from a different perspective,

7 a side view on the lids,

8th a section along line AA in 7 .

9 a 8th corresponding sectional view without lid,

10 a section through both covers with mounted suction and injection pipe,

11 a section in the longitudinal direction of the collecting tank to illustrate a partition,

12a . 12b Views of two Wellrippbleche, where in 12a a known form and in 12b a mold for a larger flat pipe density is shown,

13a . 13b each a section of a Corrugated rib of an evaporator in different geometries,

14 the amount of stored water as a function of the heat exchange area,

15 the amount of water stored as a function of the height of the ribs (in operation at a specified operating point and at the same heat exchange surfaces), and

16 the critical amount of air with respect to a splash of an evaporator depending on the rib height

A flat tube evaporator 1 (only partially shown) of a motor vehicle air conditioner, as previously with reference to the DE 198 26 881 A1 described, two collection boxes 2 , Flat tubes (not shown), between the two headers 2 run, and corrugated ribs 3 on, which are arranged between the flat tubes. Every collection box 2 is formed according to the embodiment of a circuit board, which is punched out of a sheet and then shaped so that a flat collection box part 4 and at the longitudinal edges then two tunnel-shaped collection box parts 5 are formed (see in particular 4 and 6 ). The longitudinal edges are provided with a plurality of distributed over the length arranged tabs through recesses of the flat collection box part 4 are inserted through and caulked on the flat tubes facing the outside. The ends are by means of later described in more detail lids 6 locked.

In the flat collection box part 4 are a plurality of passages 7 formed, in which the flat tubes are guided, wherein the opening of the passages 7 essentially corresponds to the outer shape of the flat tubes.

The two tunnel-shaped collection box parts 5 have due to a relatively small depth on a substantially semicircular shape, such as the representation of 7 can be removed. Due to the improved strength properties as a result of halbkreisför shaped shape of the collection box parts 5 and / or the smaller installation depth wall thicknesses of 0.8 to 1 mm in contrast to the usual wall thicknesses of 1.2 to 1.5 mm possible.

Inside the collection box 2 are one or more partitions 8th provided, through which the flow path for a fluid such as the refrigerant through the heat exchanger, in particular its flat tubes can be predetermined. The partitions 8th are through slots 9 preferably in a flat collection box part 4 insertable, the partitions 8th each between two openings or passages 7 for the tubes, such as flat tubes, are arranged and the distance of the passages 7 through the partitions 8th preferably not changed. This is for example in the collection box 2 punched or otherwise introduced in a region a partition slot, so that under certain circumstances, no draft is formed, and / or in another area a guide element, such as a guide, for example. With a depth of 0.2 to 0.3 mm, to a guide of the partition 8th provided (see 11 ).

The cover made of a sheet metal 6 are from the front side at the collecting box 2 attached, where they are up to stops formed by stop pins 10 , which are formed on the board by means of embossing, introduced and punched out in the manufacture of the board and after the positioning of the lid 6 bent tabs 11 are locked. For easier insertion of the lid 6 be provided chamfers on the board (see about half of the board thickness going bevel in 9 ). Both the tabs 11 as well as the attacks 10 in the tunnel-shaped collection box part 5 are located in the longitudinal direction of the collecting tank 2 each seen at the same height. According to the present embodiment, each lid 6 in the flat collection box part 4 only one stop 10 and offset two tabs 11 provided, however, according to a variant not shown in the drawing, a tunnel-shaped collection box part 5 appropriate design possible. The tabs 11 are from the attacks 10 in the longitudinal direction of the collecting tank 2 seen around the thickness of the lid 6 forming sheet metal spaced apart, so that an exact positioning as a result of a positive connection before soldering is possible.

According to the present embodiment, the tabs 11 bent around an axis that runs parallel to the collection box longitudinal axis. According to a variant not shown in the drawing, bending of the tabs towards the cover is also possible, so that only two tabs each extending in the longitudinal direction of the collecting box need to be provided in the blank. Further, according to another variant not shown in the drawing, the limitation of the insertion of the lid may be limited by the respective first passage for the flat tubes, so that only in the tunnel-shaped collection box part stops must be provided and the total length of the collecting tank are optimally utilized can.

The refrigerant supply and discharge takes place as 10 can be removed, one on each with an opening 12 provided lid 6 attached injection pipe 13 or a suction tube 14 , The openings 9 the lid 6 are formed in the corresponding punched sheet metal part as passages, wherein the lid 6 in the collection box 2 are installed so that the edges of the passage in each case protrude outward. The initial sheet thickness of the lid 6 , ie the thickness of the unprocessed sheet, is about 1.5 mm, in order to ensure a secure solder joint on the narrow sides and a sufficient material thickness for the passages, so that also a sufficiently large connecting surface and thus a secure connection between the pipes for the refrigerant Supply and - discharge and the passages can be ensured. Here are the lids 6 without draft, at least in its outer, on the board of the collecting tank 2 flat formed adjacent edge regions.

The passage for the injection pipe 13 is formed such that the injection pipe 13 in the opening 12 down to the height of the attacks 10 is inserted. For this purpose, the passage of the lid 6 a slightly conical, tapering over the length of the passage to the outside inner diameter. The passage for the intake manifold 14 has an outwardly tapering outer diameter, wherein the suction pipe slightly widened at its end 14 pushed from the outside. The slope is at both openings 12 preferably 2-3 °, but not more than 5 °.

Preferably become five-chambered Flat tubes used in particular with a width of approx. 2.5 mm, the distance between the bars remains unchanged, so that the air-side pressure drop is not or only insignificantly elevated, compared to known evaporators of normal depth. The flow for example, the evaporator can be 6- or, especially small Block widths, 4-floods.

In 13 is the rib geometry (opening angle α between adjacent rib sections 101 over a ribbed arch 102 interconnected) at 8 mm ( 13a ) and 4.5 mm rib height ( 13b ), in each case at 60 ribs per 100 mm, shown in comparison. In 13b is a rib bow 102 with a smaller radius of curvature (compared to 13a ). In this connection, it should be noted that a radius of curvature in each point of the rib bow 102 may be different and that thus in addition to a circular arc-shaped cross-section, other symmetrical or asymmetrical shapes of the rib bow 102 possible are.

For example with a depth of T = 40 mm come to a ribs with a fin height h = 4.5 mm for use, creating more ribs and flat tubes or a higher one Rib efficiency and more heat transfer surface - at the same Evaporator size - be enabled. In this way, a higher Power density achieved.

14 shows the stored amounts of water as a function of the heat exchange area of proven heat exchangers, the fin height 1 bigger than the rib height 2 is and the rib height 2 bigger than the rib height 3 is. Here is also a positive influence of the smaller rib height on the storage capacity noticeable. The values were determined by means of a simple screening test, in which first the evaporators are immersed in a water bath and, after removal after a certain dripping time, the remaining amount of water remaining in the evaporator is determined by weighing.

In 15 are the stored on the heat exchange surface stored amounts of water as a function of the rib height shown, the rib height decreases to the right. The values were determined during operation at a given operating point.

In 16 the critical air volumes are plotted above the rib height, starting from which a spraying of the respective evaporator starts (values likewise determined during operation). The rib height here increases to the right.

In evaporators according to the prior art, the opening angle α is about 14 ° (at 60 fins per 100 mm), or lower. With the new rib geometry (H = 4.5 mm, T = 40 mm), angles of approx. 28 ° can be achieved (again with 60 ribs per 100 mm) (cf. 13 ). For even smaller version of the radii of curvature of the rib arches 102 the opening angle can be further increased.

by virtue of of the improved syringe performance are also higher rib densities permissible which in turn have a positive impact on performance, though This causes the opening angle again slightly reduced. In a preferred embodiment, a 4.5 comes mm high rib with a rib density of> = 70 ribs per 100 mm for use, where the opening angle then about 22 °.

The resulting angle at a 6 mm high rib is between 15 ° and 22 ° (evaporator with 6 mm high rib also already show a much better drainage and storage behavior as evaporator mti 8 mm high rib, here is also the number of drainage surfaces or flat tubes already higher). The water separation is also favored by a larger to Available drainage surface along the flat tubes or by the larger number of drainage surfaces / flat tubes with a comparable amount of condensate.

Claims (17)

Heat exchangers, in particular flat-tube evaporators ( 1 ) for a motor vehicle air conditioning system, with at least one collecting tank ( 2 ) of sheet metal, which is divided in the longitudinal direction at least in two chambers and in the bottom of the ends of tubes, in particular of flat tubes, are introduced, and the collecting box ( 2 ) a tunnel-shaped collection box part ( 5 ), a substantially flat collection box part ( 4 ), which forms the bottom, and at the front each cover ( 6 ), characterized in that at least one lid ( 6 ) is formed flat at least in its outer edge region and is positively positioned in the collecting box. Heat exchanger according to claim 1, characterized in that the lid ( 6 ) is introduced from the front side and collecting box side of several stops ( 10 ) located at the tunnel-shaped collection box part ( 5 ) and / or at the flat collection box part ( 4 ) are formed. Heat exchanger according to claim 1 or 2, characterized in that the cover ( 6 ) by means of bent tabs ( 11 ) is locked. Heat exchanger according to claim 3, characterized in that the tabs ( 11 ) Part of the tunnel-shaped collection box part ( 5 ) and / or the flat collection box part ( 4 ) are. Heat exchanger according to one of the preceding claims, characterized in that the cover ( 6 ) an opening ( 12 ) for- has the refrigerant supply or -Abführung whose edge is bent in particular outwards. Heat exchanger according to claim 5, characterized in that the opening ( 12 ) is designed as a passage. Heat exchanger according to claim 5 or 6, characterized in that the opening ( 12 ) is conical with an angle of at most 5 °, in particular 2 ° to 3 °. Heat exchanger according to one of claims 5 to 7, characterized in that a suction pipe ( 14 ) attached to the lid ( 6 ) with an opening ( 12 ), has an inner diameter which is about the outer diameter of the opening ( 12 ) narrowing edge corresponds. Heat exchanger according to one of claims 5 to 8, characterized in that an injection pipe ( 13 ) attached to the lid ( 6 ) with an opening ( 12 ), has an outer diameter which corresponds approximately to the smallest inner diameter of the opening delimiting edge. Heat exchanger according to one of the preceding claims, characterized in that the edge of the collecting box sheet for the cover ( 6 ) has an insertion bevel. Heat exchanger according to one of the preceding claims, characterized in that the two tunnel-shaped collection box parts ( 5 ) have a substantially semicircular shape. Heat exchanger according to one of the preceding claims, characterized in that partitions ( 8th ) are arranged in the heat exchanger is such that the heat exchanger is flowed through 4 or more flooded. Heat exchanger, in particular according to one of the preceding claims, with flat tubes and corrugated fins, with at least one collecting box, in the bottom of the ends of the flat tubes are inserted, wherein the corrugated fins have a rib height corresponding to the distance of each two flat tubes, and wherein two each via a Ribbed rib sections are inclined at an opening angle α to each other, characterized in that the corrugated rib ( 3 ) has a height of 3 to 6 mm, preferably of 4 to 5 mm, and a rib density of 50 to 90 ribs, preferably from 60 to 80 ribs, more preferably 70 ribs, per 100 mm. heat exchangers according to one of the preceding claims, characterized that the opening angle at least two rib sections, preferably many or all rib sections, 22 ° +/- 7 ° or 30 ° +/- 10 °. Heat exchanger according to one of the preceding claims, characterized that one or more ribs at least partially a radius of curvature of less than 0.4 mm, preferably less than or equal to 0.35 mm, especially preferably less than or equal to 0.3 mm. heat exchangers according to one of the preceding claims, characterized that the flat tubes have a width of about 1.5 to 3 mm. Automotive air conditioning characterized by an evaporator according to one of vorherge existing claims.