FR2728665A1 - Three fluid heat exchanger for vehicle air conditioning - Google Patents

Abstract

The triple heat exchanger comprises a series of envelopes (1) stacked from right to left over a height (H). The envelopes have a constant thickness and are constituted by two sheet metal plates (5,6). Each plate is formed by two juxtaposed rectangles forming two separated volumes in which the second and third fluids circulate. The envelopes are separated by gaps (3), each provided with a thin undulating heat conducting plate (4). The crests of these plates are in alternate contact with the envelope faces forming the gap. Air flows in the gaps inside horizontal channels delimited by the plate undulations exchanging heat through these plates and the casing walls with the fluid circulating in these latter.

Description

Simplified three-fluid heat exchanger
The invention relates to a triple heat exchanger for the exchange of heat between a first fluid in the gaseous state and second and third fluids circulating in separate circuits, having a series of flat-shaped intervals stacked in a direction d stack alternately with a first series of flat veins and a second series of flat veins in which the second and third fluids circulate respectively, two veins belonging respectively to the two series being juxtaposed between two consecutive intervals and each of them being separated from each of these two intervals by heat conducting walls suitable for being swept by a current of the first fluid flowing in said intervals.

Such a heat exchanger is described in EP-A-0431917. This known heat exchanger acts as a radiator for cooling the thermal engine driving a motor vehicle, and as a condenser for an air conditioning circuit in the passenger compartment of the vehicle. The first fluid is then atmospheric air, the second fluid the engine cooling fluid and the third fluid the refrigerant of the air conditioning circuit. The two veins juxtaposed between two consecutive intervals are defined by independent pockets arranged at a certain distance from each other. The total size of this exchanger in the direction of juxtaposition of the pockets corresponds to the sum of the dimensions of a radiator and a separate condenser which would perform the same functions as it, and an additional space corresponding to the distance between the two juxtaposed pockets. In addition, the two series of pockets must be produced independently and assembled independently of one another in alternation with the intervals, which complicates the manufacture of the heat exchanger. Finally, these two series of pockets are in mutual thermal connection only by means of corrugated plates arranged in the intervals.

In the air conditioning systems of the passenger compartment, it is common to have in series in the path of the air to be treated an evaporator belonging to the refrigerant circuit, intended to cool this air, and a radiator for the heating of the air. The space available for air conditioning devices is generally poorly measured, it is tempting, to save space, to replace these two heat exchangers by a single exchanger fulfilling the two functions.

The object of the invention is to improve the triple heat exchanger according to the aforementioned document by simplifying its construction and reducing its size.

Another object is to promote, in addition to the direct heat exchange between the first fluid and each of the second and third fluids, a direct exchange between the second and third fluids. In the aforementioned example of a heat exchanger playing the role of heating radiator and evaporator, the direct heat exchange between the heat transfer fluid of the heating radiator and the refrigerant fluid of the evaporator promotes heat transfer towards the latter fluid and therefore its complete evaporation.

The invention relates in particular to a heat exchanger of the kind defined in the introduction, and provides that the two veins juxtaposed between two intervals are defined by the same flat pocket whose internal volume is separated from these two intervals by respective unit walls and in which the second and third fluids circulate on either side of a sealed separation, each of said unit walls being swept by the second fluid over a fraction of its surface and by the third fluid over the remaining fraction of its surface.

Thanks to the invention, a single series of pockets must be produced and stacked alternately with the intervals. The additional space requirement corresponding to the distance between the two juxtaposed pockets of the known exchanger is eliminated. In addition, the unitary walls of each pocket ensure a direct heat transfer between the second and third fluids, which sweep these walls respectively in regions close to their surface.

Optional, complementary or alternative characteristics of the invention are set out below - The thickness of each interval is defined by a thin corrugated heat conducting plate, the crests of which are in contact alternately with the two walls, which serves spacer between the two corresponding pockets and participates in the heat exchange between the three fluids.

- Each pocket is formed by two pressed sheet metal plates in the form of flat bowls, the concavities of which are turned towards one another and which are mutually tightly connected at their periphery.

- The two sheet metal plates are also mutually connected in a median zone of their width and over their entire length to achieve said watertight separation, as well as in a median zone of the width of each of the spaces thus delimited for circulation second and third fluids, and over a substantial fraction of the length of said space from a first end thereof, so as to define for the corresponding fluid a U-shaped path whose two branches extend from one side and on the other side of said middle zone of this space.

- The depth of the bowl formed by each plate is increased in a region adjacent to said first end, on either side of said central area, to form a fluid inlet chamber in the corresponding space and a outlet of the fluid from this same space, the pairs inlet chamber-outlet chamber of a series of spaces intended for the same fluid being aligned in said direction, on one side of the stack, the bottom of a bowl in said region being in leaktight contact with the bottom of a bowl formed by a neighboring pocket, around an opening formed in each of these two bottoms, to allow the passage of the fluid, in a sealed manner vis-à-vis the outside of the pockets, from one to the other of the inlet and / or outlet chambers defined by the two bowls.

- The entry and exit rooms of a series of spaces on the one hand, the entry and exit rooms of the other series of spaces on the other hand, are aligned on two opposite sides of the stack, the chambers belonging to the spaces of each series projecting from the corresponding side with respect to the regions of the pockets defining the spaces of the other series.

- The spaces of at least one series are interrupted at a distance from the entry and exit chambers of the other series, on the side of the stack where these chambers are located, so as to define at least one lateral zone of The stack in which the first fluid exchanges heat with only one of the second and third fluids. In an air conditioning system, the air having passed through such a lateral zone can be sent to a part of the passenger compartment where air is desired to be hotter or colder than in the other parts. If necessary, a hot air zone and a cold air zone can be provided on either side of the stack.

- The inlet chambers on the one hand and the outlet chambers on the other hand from the same series of spaces are mutually aligned to form an inlet pipe and an outlet pipe respectively, the U-shaped paths defined in said spaces being arranged in parallel between the inlet and outlet pipes.

The invention also relates to the use of a heat exchanger as defined above, in which the first, second and third fluids are respectively air intended to be sent into the passenger compartment of a vehicle, a coolant capable of passing from the liquid state to the gaseous state in the exchanger by absorbing heat, and a hot fluid capable of giving off heat to the other two fluids.

The characteristics and advantages of the invention will be explained in more detail in the description below, with reference to the appended drawings, in which - Figure 1 is a side view of the stack of intervals and pockets of a heat exchanger according to the invention; - Figure 2 is a sectional view along line II-II of Figure 1; and - Figure 3 is a partial sectional view along the line
III-III of figure 2.

The heat exchanger illustrated comprises a series of pockets 1 stacked from the left to the right in FIG. 1 over a height H measured from top to bottom in FIG. 1.

On this height, the pockets have a substantially constant thickness e and are limited by substantially planar and vertical faces, the side facing to the right of a pocket being separated from the side facing left of the next pocket by an interval 3 Each of the intervals 3 is lined with a thin corrugated plate 4 which conducts heat, the crests of which are in alternating contact with the two faces of the pockets limiting the interval. In known manner, air can circulate in the intervals 3, inside the horizontal channels delimited by the undulations of the plates 4, to exchange heat, through these plates and the walls of the pockets, with fluids which circulate in these as explained below.

All the pockets 1 are identical, each consisting of two sheet metal plates 5 and 6 which are symmetrical to one another with respect to a plane. As shown in Figure 2, each plate 5 or 6 has a contour formed by the juxtaposition of two rectangles of the same dimensions, these two rectangles being joined together on a large side and offset relative to each other, in their direction longitudinal, of a small fraction of their length. The two rectangular parts 6-1, 6-2 of the plate 6 shown in FIG. 2 are stamped in the form of bowls and the plates 5 and 6 of the same pocket are combined between them in leaktight fashion over the substantially rectangular outline of each bowl to define two closed interior volumes, on either side of the median junction zone 2 corresponding to the common side part of the two rectangles. The lower side 15-1 of the regions 1-1 of the pockets 1 formed by the rectangular part 6-1 of a plate 6 and the associated rectangular part 5-1 of a plate 5 is located at the lower limit of the height H , and these same 1-1 half-pockets protrude upwards beyond the upper limit of this height. In the region thus overhanging the height H, the depth of the bowls formed by the rectangular parts 5-1 and 6- 1 is increased, compared to the constant shallow depth that they present over the height H, so that the flat bottom 7 of the part 5-1, convex to the left, of a pocket 1 comes to rest on the flat bottom 8 of part 6-1, convex to the right, of the pocket located to the left of the previous one. The thickness of each pocket is thus equal in this region to the pitch of the alternating stack, on the height H, of the intervals 3 and of the pockets. In the same way, the upper side 15-2 of the half-pockets 1-2 formed by the rectangular part 6-2 of a plate 6 and the associated rectangular part 5-2 of a plate 5 is situated at the upper limit of the height H, and these half-pockets extend downwards beyond the lower limit of the height H, by thickening and coming into mutual contact by flat bottoms 7 and 8 turned respectively to the left and to the right.

The plates 5 and 6 of each pocket are further sealed in two median zones 9-1 and 9-2 relative to the width of the half-pockets 1-1 and 1-2, each extending continuously from the end edge 14-1 or 14-2 of the corresponding half-pocket situated above or below the height H up to a certain distance from the opposite edge 15-1 or 15-2. The internal volume of each of these half-pouches therefore has a U-shaped configuration, the ends of the two arms 10 and 11 of which are located in the thickened region of the pouch, each of the flat bottoms 7, 8 being separated into two parts 7a and 7b. , 8a and 8b, via the connection zone 9-1 or 9-2. Each of the parts 7a, 7b, 8a, 8b is pierced with an opening 12. The openings 12 of two adjacent bottom parts ensure communication between the thickened ends of the branches of the U-shaped paths of two half-pockets 1-1 or 1 -2 neighbors. The thickened ends 13a of the arms 10 constitute inlet chambers for the fluid in each pocket and are interconnected by the corresponding openings 12 to form an inlet pipe. Similarly, the thickened ends 13b of the branches 11 constitute fluid outlet chambers from each pocket and are joined together, by the corresponding openings 12, to form an outlet pipe.

Each fluid circulates in parallel, in the corresponding U-shaped paths of the different pockets, between the inlet pipe and the outlet pipe. Of course, the bottom part 7a or 7b and the mutually adjacent bottom part 8a or 8b of two neighboring pockets are tightly connected around their openings 12. One of the two openings 12 located at the ends of each pipe d 'inlet or outlet is connected to an inlet or outlet manifold of the exchanger not shown, the other opening being closed.

Claims (9)

Claims 1. Triple heat exchanger for heat exchange between a first fluid in the gaseous state and second and third fluids circulating in separate circuits, having a series of flat-shaped intervals (3) stacked in a direction d stack alternately with a first series of flat veins and a second series of flat veins in which the second and third fluids flow respectively, two veins belonging respectively to the two series being juxtaposed between two consecutive intervals and each of them being separated from each of these two intervals by walls (5-1, 5-2, 6-1, 6-2) conductive of heat suitable for being swept by a current of the first fluid flowing in said intervals, characterized in that the two veins juxtaposed between two intervals are defined by the same flat pocket (1) whose internal volume is separated from these two intervals by unitary walls r perspectives (5, 6) and in which the second and third fluids circulate on either side of a sealed separation (2), each of said unit walls being swept by the second fluid over a fraction of its surface (5-1 , 6-1) and by the third fluid on the remaining fraction (5-2, 6-2) of its surface. 2. Heat exchanger according to claim 1, characterized in that the thickness of each interval is defined by a thin plate (4) corrugated heat conducting, the crests of which are in alternating contact with the two walls, which serves as 'spacer between the two corresponding pockets and participates in the heat exchange between the three fluids. 3. Heat exchanger according to one of claims 1 and 2, characterized in that each pocket is formed of two sheet metal plates (5, 6) stamped in the form of flat bowls, the concavities of which face one towards the 'other and which are mutually connected in a sealed manner at their periphery. 4. Heat exchanger according to claim 3, characterized in that the two sheet plates are further connected to each other in a central region (2) of their width and over their entire length to achieve said sealed separation, as well as in a median zone (9-1, 9-2) of the width of each of the spaces thus delimited for the circulation of the second and third fluids, and over a significant fraction of the length of said space from a first end (14 -1, 14-2) of the latter, so as to define a U-shaped path for the corresponding fluid, the two branches (10, 11) of which extend on either side of said middle zone of this space. 5. Heat exchanger according to claim 4, characterized in that the depth of the bowl formed by each plate is increased in a region adjacent to said first end, on either side of said median zone, to form a chamber ( 13a) inlet of the fluid into the corresponding space and a chamber (13b) for outlet of the fluid from this same space, the pairs inlet chamber and outlet chamber of a series of spaces intended for the same fluid being aligned in said direction, on one side of the stack, the bottom (7) of a bowl in said region being in sealed contact with the bottom (8) of a bowl formed by a neighboring pocket, around an opening (12) formed in each of these two bottoms, to allow the passage of the fluid, in a sealed manner vis-à-vis the outside of the pockets, from one to the other of the inlet and / or outlet chambers defined by the two bowls. 6. Heat exchanger according to claim 5, characterized in that the inlet chambers and the outlet chambers of a series of spaces on the one hand, the inlet chambers and the outlet chambers on the other series of spaces on the other hand, are aligned on two opposite sides of the stack, the chambers belonging to the spaces of each series projecting from the corresponding side with respect to the regions of the pockets defining the spaces of the other series. 7. Heat exchanger according to claim 6, characterized in that the spaces of at least one series are interrupted at a distance from the inlet and outlet chambers of the other series, on the side of the stack where there are these chambers, so as to define at least one lateral zone of the stack in which the first fluid exchanges heat with only one of the second and third fluids. 8. Heat exchanger according to one of claims 5 to 7, characterized in that the inlet chambers on the one hand and the outlet chambers on the other hand of the same series of spaces are mutually aligned to form an inlet pipe and an outlet pipe respectively, the U-shaped paths defined in said spaces being arranged in parallel between the inlet and outlet pipes. 9. Use of a heat exchanger according to one of the preceding claims, in which the first, second and third fluids are respectively air intended to be sent into the passenger compartment of a vehicle, a coolant specific to to pass from the liquid state to the gaseous state in the exchanger by absorbing heat, and a hot fluid suitable for yielding heat to the two other fluids.