EP2901098B1 - Heat exchanger for gas, particularly the exhaust gases of an engine - Google Patents

Description

The present invention refers to a gas heat exchanger according to the preamble of claim 1, in particular exhaust gases from an engine. Such an exchanger is known from JP 2001 027 158 A . The invention is particularly applicable to exhaust gas recirculation exchangers (EGRC).

PRIOR STATE OF THE TECHNIQUE OF THE INVENTION

In some heat exchangers for gas cooling, for example those used in exhaust gas recirculation systems to the admission of an internal combustion engine, the two media that exchange heat are separated by a partition.

The current configuration of EGR exchangers on the market is a metal heat exchanger typically made of stainless steel or aluminum.

There are essentially two types of EGR heat exchanger: a first type consists of a carcass inside which is disposed a bundle of parallel tubes for the passage of gases, the refrigerant flowing through the carcass, outside the tubes, and the second type consists of a series of parallel plates which constitute the heat exchange surfaces, so that the exhaust gases and the refrigerant circulate between two plates, in alternating layers, the heat exchange being able to be improved by the added fins.

In the case of heat exchangers with tube bundle, the connection between the tubes and the carcass can be of different types. Generally, the tubes are fixed at their ends between two support plates coupled to each end of the carcass, the two support plates having a plurality of orifices for positioning the respective tubes.

Said support plates are in turn attached to connection means to the recycling line, which may consist of a V-shaped connection or a peripheral flange connection or flange, according to the design of the recycling pipe where is mounted the exchanger. The peripheral rim can be mounted with a gas tank, so that the gas tank is an intermediate piece between the carcass and the rim, or the rim can be mounted directly on the carcass.

In both types of EGR exchangers, their components are mostly metallic, so they are mounted mechanically and then oven-welded or arc-welded or laser-welded to provide the proper seal required for this purpose. application. In some cases, some plastic components may also be included, which may have a single function or various functions integrated in a single room.

The main function of the EGR exchangers is the heat exchange between the exhaust gas and the refrigerant, in order to cool the gases. In addition, the EGR exchanger must meet other secondary functions to be mounted on the engine block, allow connection with the refrigerant, or allow connection with the exhaust gas circuit, among others. Currently, the various components of the exchanger are joined to the carcass by welding in the oven or by arc welding or laser welding.

Some existing tube or plate EGR exchangers have deflectors, which are placed inside the refrigerant circuit. The design and number of baffles may vary from application to application, depending on the usage requirements and restrictions of the vehicle manufacturer, in terms of operating conditions or conditioning restrictions of the exchanger.

In most cases, the baffles are used to improve the circulation of the refrigerant around the tubes of gases, thus avoiding the stagnation points that could cause the boiling of the refrigerant inside the exchanger, and to improve the refrigeration of all tubes for better performance of the exchanger.

In other cases, the baffles are included to avoid mechanical problems that may occur in the working conditions of the exchanger in the engine.

An EGR exchanger is known which uses a longitudinal baffle which divides the inside of the carcass into two halves to bypass coolant from one half of the carcass to the other when the inlet and outlet ducts refrigerant outlet are on the same side of the carcass. This deflector is attached to the carcass of the exchanger by welding points and has a length slightly less than the length of the carcass. Spanish patent application no. 200931016 , still unpublished, of the same holder as that of the present application, comprises a plurality of deflectors arranged transversely along the inside of the carcass. Each deflector has a surface smaller than the transverse surface of the carcass which allows the partial passage of the refrigerant fluid. Said deflectors are not aligned with each other but placed alternately, leaving the coolant passage zones alternately distributed, thus ensuring a proper distribution of the coolant, in addition to improving the mechanical resistance to vibration. In addition, said deflectors are fixed to the carcass by welding in the oven.

Licences JP2002292089 and JP2000283666 comprise a plurality of plate-shaped transverse deflectors disposed within a circular cutting carcass. The design of said baffles is very similar to the configuration of the support plates at both ends of the carcass, the diameter of said baffles being equal to the inside diameter of the carcass, and have openings which allow the passage of refrigerant through them. The positions of said passage openings in the different deflectors are distributed alternately.

• les échangeurs thermiques qui permettent l'utilisation de deux circuits de fluide réfrigérant, qu'il s'agisse du même fluide ou non.
• Les échangeurs thermiques qui doivent refroidir deux fluides chauds, qu'il s'agisse du même fluide ou non.
• Les échangeurs thermiques dont les conduits d'entrée et de sortie du fluide réfrigérant se trouvent du même côté de la carcasse.

In general, the use of baffles inside heat exchangers is becoming more widespread and more frequent in recent years due to environmental legislation and design restrictions on certain types of heat exchangers, such as:

• heat exchangers that allow the use of two refrigerant circuits, whether the same fluid or not.
• Heat exchangers that must cool two hot fluids, whether the same fluid or not.
• The heat exchangers in which the inlet and outlet ducts of the refrigerant are on the same side of the carcass.

The main problem posed by the use of baffles is to ensure an adequate seal between the two circuits defined in the shell of the exchanger when two types of coolants are used, which is related to the manner of mounting and fixing this deflector inside the carcass, usually by means of welding points, respecting both the mechanical behavior that must present the exchanger to meet the specifications of the vehicle manufacturer.

Another problem with this type of baffle is to ensure the proper position and orientation of the deflector when it is mounted in the carcass before welding.

DESCRIPTION OF THE INVENTION

The purpose of the gas heat exchanger, in particular the exhaust gases of an engine of the present invention is to overcome the disadvantages of exchangers known in the art, by providing a baffle for improving the distribution of a refrigerant fluid that circulates in the exchanger, or even to separate two different refrigerants without communication between them within the same carcass, allowing a more effective mounting of said baffle inside the exchanger.

The gas heat exchanger, in particular the exhaust gas of an engine, object of the present invention, is in accordance with claim 1.

In this way, a simpler positioning and mounting of the deflector are made inside the carcass, and a better attachment thereof through its connection by welding. Preferably the baking is used, thus avoiding the use of soldering points as for deflectors known in the art.

Advantageously, the deflector includes in its longitudinal edges two folded peripheral fins intended to come into contact with the inner walls of the carcass for its connection by welding.

The use of said peripheral fins and projecting segments ensures proper positioning and orientation of the deflector within the carcass, prior to its attachment by welding.

In a first embodiment, the deflector comprises a closed surface to prevent communication between the two circuits in the carcass;

In this case, the exchanger comprises two pairs of inlet and outlet ducts provided for the distribution of two different refrigerant fluid streams.

According to a second embodiment, the deflector comprises a through opening in its surface capable of communicating two circuits in the carcass.

In this other case, the exchanger comprises a pair of inlet and outlet conduits disposed in the same end of the carcass for dispensing a flow of refrigerant fluid.

BRIEF DESCRIPTION OF THE DRAWINGS

• la figure 1 est une vue en perspective et partiellement en coupe de l'échangeur thermique de l'invention, montrant l'emplacement du déflecteur et les deux circuits par lesquels circulent respectivement deux fluides réfrigérants ;
• la figure 2 est une vue en perspective du déflecteur selon une première réalisation de l'invention ;
• la figure 3 est une vue en perspective du déflecteur selon une seconde réalisation de l'invention ;
• la figure 4 est une vue en perspective d'un type d'échangeur qui utilise un même type de fluide réfrigérant avec ses conduits d'entrée et de sortie situés dans une même extrémité de la carcasse ;
• la figure 5 est une vue en coupe de l'échangeur de la figure 4, montrant le déflecteur utilisé et le parcours du fluide réfrigérant ;
• la figure 6 est une vue en perspective d'un déflecteur montrant les ailettes longitudinales de fixation ;
• la figure 7 est une vue partielle en perspective de la carcasse de l'échangeur, montrant le déflecteur monté et fixé aux parois internes de la carcasse grâce aux ailettes longitudinales ;
• les figures 8 et 9 sont des vues en perspective et en plan respectivement d'une extrémité du déflecteur selon l'invention, montrant un segment saillant prévu pour l'emboîtement avec une plaque de support des tubes ;
• la figure 10 est une vue en perspective d'une plaque de support, montrant une rainure d'emboîtement destinée à recevoir le segment saillant du déflecteur ;
• la figure 11 est une vue en perspective du déflecteur monté dans la plaque de support illustrée à la figure 10 ;
• les figures 12 et 13 sont respectivement des vues en perspective de deux configurations d'échangeurs thermiques qui utilisent deux types de fluides réfrigérants différents, montrant l'emplacement des paires respectives de conduits d'entrée et de sortie des deux fluides réfrigérants ; et
• la figure 14 est une vue en coupe et en perspective d'un échangeur thermique qui utilise un fluide réfrigérant unique, montrant l'emplacement de la paire de conducteurs d'entrée et de sortie situés dans une même extrémité de la carcasse.

In order to facilitate the description of what has been mentioned above, we enclose drawings which represent, schematically and solely by way of non-limiting example, a practical case of realization of the gas heat exchanger, in particular exhaust gases. of an engine of the invention, in which:

• the figure 1 is a perspective view and partially in section of the heat exchanger of the invention, showing the location of the deflector and the two circuits through which respectively circulating two refrigerants;
• the figure 2 is a perspective view of the deflector according to a first embodiment of the invention;
• the figure 3 is a perspective view of the deflector according to a second embodiment of the invention;
• the figure 4 is a perspective view of a type of exchanger that uses the same type of refrigerant with its inlet and outlet ducts located in the same end of the carcass;
• the figure 5 is a sectional view of the exchanger of the figure 4 showing the deflector used and the refrigerant flow;
• the figure 6 is a perspective view of a deflector showing the longitudinal fixing fins;
• the figure 7 is a partial perspective view of the carcass of the exchanger, showing the deflector mounted and fixed to the internal walls of the carcass with the longitudinal fins;
• the Figures 8 and 9 are views in perspective and in plan respectively of one end of the deflector according to the invention, showing a projecting segment provided for interlocking with a support plate of the tubes;
• the figure 10 is a perspective view of a support plate, showing an interlocking groove for receiving the projecting segment of the deflector;
• the figure 11 is a perspective view of the deflector mounted in the support plate shown in FIG. figure 10 ;
• the Figures 12 and 13 are respectively perspective views of two configurations of heat exchangers that use two different types of coolant fluids, showing the location of the respective pairs of inlet and outlet conduits of the two refrigerant fluids; and
• the figure 14 is a sectional view in perspective of a heat exchanger that uses a single refrigerant, showing the location of the pair of input and output conductors located in the same end of the carcass.

DESCRIPTION OF A PREFERRED EMBODIMENT

To the figure 1 is partially shown a heat exchanger 1 which comprises a bundle of tubes (not shown for reasons of clarity) disposed inside a carcass 2, defining an inlet 3 and a gas outlet 4, said tubes being intended for circulation gases with a heat exchange with at least one refrigerant. The tubes are fixed at their ends between two support plates 5 coupled in each end of the carcass 2, the two support plates 5 having a plurality of orifices for positioning the respective tubes.

Thus, the exchanger 1 comprises deflection means disposed inside the carcass 2 capable of directing the at least one refrigerant fluid in the carcass 2. In this case, the deflection means comprise a substantially parallel longitudinal deflector 6 to the bundle of tubes, for dividing the carcass 2 into two circuits.

The deflector located in the casing 2 of the exchanger 1 makes it possible to improve the distribution of a refrigerant fluid or even to separate two different fluids, just like oil and a refrigeration fluid, without communication between the two. inside a common carcass 2. Two embodiments of the deflector are shown below.

According to a first embodiment shown in figure 2 , the deflector 6 comprises a closed and homogeneous surface which allows a perfect seal between the circuits of two refrigerants. The purpose of said deflector 6 is to separate two different refrigerants in the interior of the carcass 2, because of their compositions, properties, etc. different. This type of deflector 6 is used in exchangers in which it is necessary to use different refrigerant circuits in the exchanger to produce heat exchange with the exhaust gas flowing in the tubes.

To the figure 1 is illustrated an exchanger 1 which uses said deflector 6 to separate two types of refrigerant. In this case, two different inlet ducts 7, 7a, and two different outlet ducts 8, 8a are required in the same exchanger 1. In this way, an adequate separation of the two refrigerants in the same carcass 2 is achieved. To the figure 1 , entry and exit the two refrigerants in the carcass 2, and the entry and exit of the gases in the carcass 2 and their change of direction in a gas tank (not shown) are shown.

According to a second embodiment shown in figure 3 , the deflector 6a comprises a through opening 9 in its surface for the passage of a refrigerant from one half to another half of the carcass 2, to optimize the distribution of the refrigerant in the carcass 6. This type 6a deflector is used to increase the yields or improve the distribution of the refrigerant in the carcass 2.

The Figures 4 and 5 illustrate an exchanger 1 which uses said deflector 6a, whose input 7 and output 8 conductors are located in the same end of the carcass 2. A figure 4 the inlet and outlet of the refrigerant in the carcass 2 are represented by arrows.

Due to packaging restrictions or requirements of the vehicle manufacturer, it is possible that the inlet 7 and the outlet 8 of the coolant have to be placed at a short distance from each other or even same end of the carcass 2, which may cause a preferable path for the coolant and affect accordingly the filling of the refrigerant and lead to poor refrigeration of the gas tubes, and also give rise to stagnation points that can cause a phenomenon boiling water may damage the heat exchanger. In this case, the deflector 6a provided with its opening 9 improves the circulation of the refrigerant in the exchanger.

The configuration of the baffle 6, 6a of the present invention includes peripheral fins bent in its two longitudinal edges, as can be seen in FIG. figure 6 , intended to connect the baffle 6, 6a to two internal walls of the carcass 2, preferably by baking (see FIG. figure 7 ). In this way, the use of welding points between the deflector 6, 6a and the carcass 2 as used with the deflectors known in the state of the art is abolished.

Thus, the deflector 6, 6a of the present invention includes in its transverse edges two projecting segments 11, as illustrated by FIGS. figures 6 , 8 and 9 , capable of fitting into respective grooves (12) made in the support plates 5 (see Figures 10 and 11 ), allowing the deflector 6, 6a to remain fixed at the appropriate position before welding. In this case, the mounting of the deflector 6, 6a is carried out in a manner similar to the process of mounting the tubes with said support plates 5.

For example, figures 1 , 12 and 13 respectively illustrate different configurations of exchangers 1 which use two refrigerants, their respective inlet ducts 4, 4a and 8a outlet 8a being arranged at different positions relative to the carcass 2. In this case, a closed baffle 6 is used (see figure 2 ) to separate the two refrigerants.

On the other hand, figures 4 and 14 respectively show different configurations of exchangers that use the same refrigerant whose pair of inlet ducts 7 and outlet 8 is located in the same end of the carcass 2, said ducts 7, 8 being arranged at different relative positions in the casing 2. In this case, a deflector 6a provided with a through opening 9 (see FIG. figure 3 ) to improve the distribution of the coolant is used.

The deflector 6, 6a of the invention can be used in exchangers made of stainless steel or aluminum.

Claims (6)

1. Heat exchanger (1) for gas, in particular the exhaust gases of an engine, comprising a bundle of tubes arranged inside a shell (2) and intended for the circulation of gas with an exchange of heat with at least one stream of refrigerant fluid, said tubes being fixed by their ends between two support plates (5) coupled at each end of the shell (2), and deflection means arranged inside the shell (2) able to direct the at least one stream of refrigerant fluid inside the shell (2), the deflection means comprising a longitudinal deflector (6, 6a) substantially parallel to the tube bundle and intended to divide the shell (2) into two circuits, said deflector (6, 6a) being fixed by its longitudinal edges to the internal walls of the shell (2) and by its transverse edges to the two support plates (5) by welding, characterized in that the deflector (6, 6a) includes in its transverse edges two protruding segments (11) able to engage in respective grooves (12) produced in the support plates (5) for its connection by welding.
2. Exchanger (1) according to Claim 1, wherein the deflector (6, 6a) includes in its longitudinal edges two folded peripheral fins (10) intended to come into contact with the internal walls of the shell (2) for its connection by welding.
3. Exchanger (1) according to Claim 1, wherein the deflector (6) comprises a closed surface to prevent communication between the two circuits in the shell (2).
4. Exchanger (1) according to Claim 3, which includes two pairs of inlet pipes (7, 7a) and outlet pipes (8, 8a) provided for distribution of two different streams of refrigerant fluid.
5. Exchanger (1) according to Claim 1, wherein the deflector (6a) comprises a through opening (9) in its surface able to bring the two circuits into communication in the shell (2).
6. Exchanger (1) according to Claim 5, comprising a pair of inlet (7) and outlet pipes (8) arranged at a same end of the shell (2) for distribution of a stream of refrigerant fluid.

Images