Heat exchanger for gases, in particular for the exhaust gases of an engine

Abstract

A heat exchanger (1) for gases, in particular for the exhaust gases of an engine includes a bundle of tubes (2) arranged inside a casing (3) defining a gas inlet (4) and outlet (5). The tubes (2) being intended for the circulation of the gases with a view to exchanging heat with a coolant, and the tubes (2) being distributed in at least one column having a plurality of rows defining a plurality of spaces (8) between the rows, and including a coolant inlet pipe (9) and outlet pipe (10) connected to the casing (3). The exchanger (1) includes a bypass channel (11) incorporated into the casing (3) capable of connecting the spaces (8) defined between the rows of tubes (2) located in front of the channel (11) with one of the coolant pipes (10), in such a way as to improve the distribution of the coolant.

Claims

1. A heat exchanger (1) for gases, the heat exchanger (1) comprising a bundle of tubes (2) arranged inside a casing (3) defining a gas inlet (4) and a gas outlet (5), the tubes (2) being configured for the circulation of the gases with a view to exchanging heat with a coolant, and the tubes (2) being distributed in at least one column having a plurality of rows defining a plurality of spaces (8) between the rows, and comprising a coolant inlet pipe (9) and coolant outlet pipe (10) connected to the casing (3), and a bypass channel (11) incorporated into the casing (3) and connecting the spaces (8) defined between the rows of tubes (2) located facing the bypass channel (11) with the coolant outlet pipe (10) to improve the distribution of the coolant, wherein the bypass channel (11) is associated with a closing plate (12) coupled to the casing (3) in the inner space located facing the channel (11), the closing plate (12) comprising at least one lateral through opening (13) provided to allow controlled passage of coolant between an inside of the casing (3) and the bypass channel (11); and wherein said closing plate (12) is a single piece closing plate (12) and has a first portion disposed perpendicular to a length of said tubes and a second portion disposed parallel to the length of said tubes.

2. A heat exchanger (1) according to claim 1, wherein a height of the tubes (2) is less than a width of the tubes (2), and wherein the coolant outlet pipe (10) is positioned facing a widest side of the tubes (2).

3. A heat exchanger (1) according to claim 1, wherein the bypass channel (11) is manufactured using a stamping process, and the bypass channel (11) is configured to project towards an outer portion of the casing (3).

4. A heat exchanger (1) according to claim 1, wherein the closing plate (12) comprises two lateral through openings (13).

5. A heat exchanger (1) according to claim 1, wherein the closing plate (12) comprises a set of lateral openings (13) each associated with a space (8) positioned every two rows of tubes (2) for allowing passage of coolant, and at least one upper opening (13a) located facing the coolant outlet pipe (10) positioned adjacent to the gas inlet (4) for allowing passage of coolant.

6. A heat exchanger (1) according to claim 1, wherein the bypass channel (11) comprises a lateral opening provided for connecting a second coolant outlet pipe (10a).

7. A heat exchanger (1) according to claim 1, which comprises two bypass channels (11, 11a) arranged respectively on opposite sides (3b) of the casing (3).

8. A heat exchanger (1) according to claim 1, wherein the bypass channel (11) has a variable cross section over its entire length.

9. A heat exchanger (1) according to claim 1, wherein said closing plate (12) including said at least one lateral through opening (13) and said bypass channel (11) are arranged such that output flow of coolant is configured to cross said plurality of spaces (8).

10. A heat exchanger (1) according to claim 9, wherein said closing plate (12) including said at least one lateral through opening (13) and said bypass channel (11) are arranged such that output flow of coolant is configured to not cross a space (7) defined between said columns.

11. A heat exchanger (1) according to claim 1, wherein said closing plate (12) has an “L” shape.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In order to clarify the above description drawings are appended which illustrate, in schematic form and purely by way of non-limiting example, practical embodiments of the heat exchanger for gases, in particular for the exhaust gases of an engine of the present invention. In said drawings:

(2) FIG. 1 is a perspective view of a heat exchanger known from the prior art which illustrates a possible configuration of inlet and outlet coolant pipes;

(3) FIG. 2 is a longitudinal section of the heat exchanger of FIG. 1, which illustrates schematically the distribution lines of the coolant;

(4) FIG. 3 is partial front view of the exchanger of FIG. 1, which illustrates the coolant outlet pipe and its position relative to the gas tubes;

(5) FIG. 4 is a schematic view of a cross section of the coolant outlet pipe of the exchanger of FIG. 1, which indicates its position above the space between two columns of tubes;

(6) FIG. 5 is a partial perspective view of the heat exchanger according to the invention, which illustrates the channel stamped into a lateral wall of the casing;

(7) FIG. 6 is a perspective view of the inner closing plate of the invention, according to a first embodiment;

(8) FIG. 7 is a partial perspective view of the heat exchanger according to the invention, with the inner closing plate mounted on the stamped channel;

(9) FIG. 8 is a cross section of the exchanger of the invention of FIG. 7 which illustrates the distribution of coolant through the closing plate and the channel towards the corresponding outlet pipe;

(10) FIG. 9 is a partial perspective view of the heat exchanger according to the invention which illustrates a second embodiment of the inner closing plate;

(11) FIG. 10 is a cross section of the exchanger of the invention of FIG. 9 which illustrates the distribution of coolant through the closing plate and the channel towards the corresponding outlet pipe; and

(12) FIGS. 11 to 13 are cross-sectional views of the heat exchanger of the invention which illustrate respectively embodiments of the bypass channel.

DESCRIPTION OF PREFERRED EMBODIMENTS

(13) FIGS. 1 to 4 illustrate a type of heat exchanger 1′ known from the prior art which comprises a bundle of tubes 2 arranged inside a casing 3 defining a gas inlet 4 and a gas outlet 5, said tubes 2 being designed for the circulation of gases for the purpose of exchanging heat with a coolant. Furthermore, the tubes 2 are fixed at their ends between two support plates 6, 6′ connected to each end of the casing 3.

(14) In this case the tubes 2 have a substantially rectangular cross section and are distributed over two adjacent columns and a plurality of rows. Said tubes 2 thus define a space 7 between the columns and a plurality of spaces 8 between the rows, the height of said tubes 2 being less than their width. The casing 3 has a quadrangular cross section.

(15) The exchanger 1′ also comprises a coolant inlet pipe 9 and a coolant outlet pipe 10 connected to the casing 3. The input flow and output flow of coolant is indicated by respective arrows, as shown in FIGS. 1 and 2. In this case the circulation of coolant flows in a counter-current. The coolant inlet pipe 9 is connected to one side 3b of the casing 3, close to the underside 3c and the gas outlet 5, whereas the coolant outlet pipe 10 is connected to the topside 3a of the casing 3, in the centre and close to the gas inlet 4.

(16) As shown in FIGS. 3 and 4, the coolant outlet pipe 10 is located above the space 7 which separates the two columns of tubes 2. However, said space 7 between two tubes 2 is relatively small, which makes the outflow of the coolant difficult. In this case, as shown by the curved lines in FIG. 2, it is necessary to direct the coolant towards the gas inlet area 4 with a strong flow, as the temperature of the gases is raised. The better the distribution of coolant in said area 4 adjacent to the support plate 6 of the gas inlet the easier it is to control the problem of boiling caused by the raised temperature of the tubes 2 in said area 4.

(17) FIGS. 5 to 13 relate to the heat exchanger 1 of the invention, in which the reference numerals 2 to 10 coincide with those of the known exchanger 1′ described above.

(18) As shown in FIGS. 5 to 8, the heat exchanger 1 of the invention also comprises a bypass channel 11 incorporated into one side 3b of the casing 3 close to the gas inlet 4, said bypass channel 11 being capable of connecting the lateral space 8 defined between the rows of tubes 2 located facing said channel 11 with the coolant outlet pipe 10 arranged on top-side 3a of the casing 3. This structural arrangement improves in particular the distribution of coolant in the area close to the gas inlet 4.

(19) The bypass channel 11 makes it possible to obtain a coolant outlet in one side 3b of the casing 3, where said output flow crosses spaces 8 defined between the rows of tubes 2, and not the space 7 defined between the columns as in the prior art, and regardless of where the sleeve of the vehicle manufacturer is located for connecting said coolant outlet pipe 10.

(20) In this way a channel 11 is obtained for the passage of coolant, the trajectory of which can be adapted to the needs and the configuration of the engine space.

(21) In this case the bypass channel 11 is produced by a stamping process and is designed to project towards the outer part of the casing 3, as shown in FIGS. 5 and 8.

(22) Furthermore, the coolant outlet pipe 10 is mounted on the casing 3 and on one end of the channel 11 in the usual manner (see FIG. 8).

(23) Similarly, the bypass channel 11 is associated with a closing plate 12 connected to the casing 3 in the inner space located facing said channel 11, said closing plate 12 comprising at least one through opening 13 provided to allow the controlled passage of coolant from inside the casing 3 to the bypass channel 11.

(24) As a result the coolant enters into the channel 11 through one or more openings 13 formed in the closing plate 12, the number or the size of which can be modified in order to obtain an optimum distribution of coolant according to the requirements of the vehicle manufacturer.

(25) According to a first embodiment of the closing plate 12 shown in FIGS. 6 to 8, said closing plate 12 comprises two lateral through openings 13. FIG. 8 illustrates by means of two arrows the outflow of the coolant through openings 13 towards the bypass channel 11, then towards the outlet pipe 10 respectively.

(26) According to a second embodiment of the closing plate 12 illustrated in FIGS. 9 and 10, said closing plate 12 comprises a set of lateral openings 13 of small diameter each associated with a space 8 positioned every two rows of tubes 2, and a plurality of upper openings 13a located facing the coolant outlet pipe 10. Similarly in FIG. 10 the coolant outlet is shown by two arrows through the openings 13, 13a towards the bypass channel 11, then towards the outlet pipe 10 respectively.

(27) It should be noted that up to now the heat exchanger has been described with a counter-current circulation of the coolant, but clearly the circulation can also be parallel, that is with the coolant inlet on the side close to the gas inlet.

(28) Furthermore, although a bundle of tubes has been shown with two columns and a plurality of rows, other embodiments are also possible, for example having a single column and a plurality of rows.

(29) Likewise, other kinds of geometries can be used for the bypass channel 11, according to the flow of coolant and the characteristics of the engine environment. Three embodiments are described below.

(30) According to a first embodiment shown in FIG. 11, the bypass channel 11 comprises a side opening for the connection of a second coolant outlet pipe 10a.

(31) According to a second embodiment shown in FIG. 12 two bypass channels 11, 11a are used with their respective closing plate 12, 12a, arranged respectively on opposite sides 3b of the casing 3.

(32) According to a third embodiment shown in FIG. 13 the bypass channel 11 has a variable cross section over its entire length.