JPS6133972B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to exhaust gas recirculation in motor vehicle internal combustion engines, and more particularly to a device for cooling exhaust gas returned to the combustion cycle.

Since approximately 1971, the automobile industry has been adding an ever-increasing number of elements to automobiles or to automobile internal combustion engines in order to increase automobile safety or reduce the emissions inherent in exhaust gases from internal combustion engines. In other words, it has been requested that additional equipment be added. Such elements include positive crankcase ventilation, exhaust gas recirculation, evaporative control devices, and catalytic converters in the exhaust system.

Of primary interest are the emissions from the exhaust gases of internal combustion engines, which have been blamed for the smog-like conditions that occur in large cities with large numbers of automobiles traveling every day. Nitrogen oxides are one such exhaust gas, and exhaust gas recirculation cycles are used to reduce these oxides in engine exhaust gases. The formation of nitrogen oxides takes place at very high temperatures and therefore occurs at the peak temperatures of the combustion process. A slight reduction in peak temperature is required to reduce and control nitrogen oxide formation.

This reduction in temperature is achieved by introducing a small amount of inert gas into the combustion process so that the end products of combustion are continuously supplied with relatively inert gases; will be used in the correct proportions. The recirculation passageway is thus connected to the exhaust manifold and to a vacuum modulated shutoff and control valve mounted on the intake manifold for controlling the flow of exhaust gases. Recirculation or additional exhaust gas passages may be located close to the engine or integrally formed within the composite runner arrangement of the intake manifold.

However, the exhaust gas from the internal combustion engine cycle is still very hot, and it is desirable to reduce its temperature considerably before the gas is reintroduced into the combustion cycle.

Conventional devices for purifying exhaust gas from internal combustion engines include those shown in, for example, Japanese Utility Model Publication No. 37-17408 or Japanese Unexamined Patent Publication No. 48-59214. However, the device shown in the former type is designed to form an envelope of coolant around a chamber that purifies exhaust gas, but purification is performed by putting purification liquid into the chamber, so exhaust gas from automobiles, etc. It is difficult to apply it as a purification device in terms of weight reduction and miniaturization.

Furthermore, the latter type of device has problems in that it is large in size and has poor thermal efficiency, and the heat of the exhaust gas is dissipated to the outside of the heat exchanger.

The problem to be solved by the present invention is to reduce the size of a heat exchanger for exhaust gas, reduce the flow resistance or pressure drop of exhaust gas, and improve thermal efficiency.

In order to solve the above problems, a two-fluid heat exchanger according to the present invention comprises a substantially flat heat exchanger made of two pairs of metal plates, the inner pair of metal plates forming a chamber and a peripheral flange. at least one chamber having an inlet and an outlet for receiving a first fluid, the heat transfer surface being received within the chamber; formed of metal plates, the outer pair of metal plates having oppositely disposed dish-shaped portions and a peripheral flange substantially completely joined to the flange of said inner metal plate, said outer plate-shaped portion being in a chamber; cooperating with said inner dish to form a fluid enclosure substantially surrounding said inner dish and having an inlet and an outlet for receiving a second fluid therein; a side wall is separated from the side wall of the inner dish, the flange of the inner metal plate extends between the inner and outer side walls to divide the envelope into an upper portion and a lower portion; an opening for communicating between the upper envelope portion and the lower envelope portion, the inlet and outlet for said second fluid being disposed in one of the outer dish-like portions, and a central recess extending through the dish-like portion; The outer dish is configured to cut across and divide the upper envelope portion into approximately equal halves between the inlet and the outlet.

In the above configuration, the first fluid flows into the chamber from the inlet, and the second fluid enters between the inner metal plate and the outer metal plate from the inlet to form a second fluid surrounding zone surrounding the chamber. and the first fluid and the second
The heat exchanger performs heat exchange with the first fluid and prevents the heat of the first fluid from dissipating to the outside of the heat exchanger.
The first fluid that has undergone heat exchange is discharged to the outside from the first fluid outlet, and the second fluid is discharged from the second fluid outlet.

Embodiments of the present invention will be described below with reference to the drawings.

Figures 1-3 show an embodiment of the heat exchanger 31 of the present invention having a generally flat shape that allows it to fit easily and compactly along the engine within the restricted space of the engine room. The heat exchanger is formed of four stamped metal plates including a pair of symmetrical inner plates 32, 32a and a pair of substantially identical outer plates 47, 47a, the inner parts or plates being a unit or heat exchanger. The exchanger is generally flat with flat flanges 33, 33a on three sides and provided with two pairs of oppositely disposed embossments 35, 35a on the fourth side. It has flanges 34, 34a, the raised part 35 of which extends on the plane of the flanges 34, 34a and the other raised part 3.
5a extends below the plane of the flange.

The inner plates 32, 32a have oppositely concave central portions 36, 36a having generally vertical side walls 37, 37a terminating in a flange 33 and walls 38, 38a terminating in a flange 34. wall 37,
37a continues to walls 39, 39a parallel to and opposite wall 38. A generally conical embossment 40, 40a is formed in the central portion 36, 36a and terminates in an embossment 35, 35a forming an opening for an inlet conduit 41 and an outlet conduit 42. Conical embossments 40, 40a are formed on the inner plates 32, 32a as shown in FIG. Recessed central portion or dish-shaped portion 36,3
Within the central chamber 43 formed by 6a are a plurality of folded turbulators 4 extending longitudinally within the chamber so as to divide the chamber into a plurality of parallel flow paths.
4 is placed and its turbulence device or turbulator is connected to the inlet tank (not shown) for the exhaust gas.
and terminates a short distance from the end of the chamber to form an outlet tank 46.

The outer portions 47, 47a surround three sides of the heat exchanger and include flat flanges 48, 48a sandwiching the flanges 33, 33a and a generally flat flange 4 sandwiching the fourth side flanges 34, 34a.
9,49a. conical embossment 50,
50a is a central recessed portion defined by a flange 48, 48a, 49, 49a with an outer edge 51, 51a which engages and is fixed to the embossment 35, 35a; That is, they are formed in the dish-shaped portions 52, 52a. Dish-shaped part 5
2, 52a is a rear wall 45, 4 having a raised part therein;
5a and parallel to the rear walls 54, 54a.
Side walls 53, 53 converging toward 5, 55a
a, the wall has an inner dish-shaped portion 36, 36a
separated by a wall outside. A notch 56 in the dish 52 engages each inner dish 36 to divide the upper portion of the fluid envelope 57 formed between the dish 36, 36a, 52, 52a, and to permit the flow of cooling fluid. towards the lower enveloping zone.

The flanges 33 of the inner plates 32, 32a form a fluid surround 57, as shown in FIGS. 2 and 3.
fluid ports or apertures 58 are formed in oppositely disposed flanges 33 at each end of the inner portion to permit fluid flow between the upper and lower portions of the envelope. communicate. Cooling fluid inlet conduit 59 and fluid outlet conduit 6
0 are fixed to the upper dished portion 52 adjacent to the notch 56 and their conduits communicate with the upper portion of the fluid surround 57 . As indicated by the arrow in FIG.
4 through the outlet tank and the cooled gas leaves through conduit 42 (arrow B). Cooling water enters the upper half of the envelope 57 through conduits 59 and descends through openings 58 into the lower envelope section, flows across the lower envelope section and through the opposite set of openings 58 into the upper envelope section. It flows into the other half of the band and exits through conduit 60 (arrow D) to cool the exhaust gas.

4, 5 and 6 show a second embodiment of the heat exchanger having a substantially rectangular symmetrical shape. The device consists of a pair of inner metal plates 6 having parallel side flanges 63 and curved end flanges 64.
2, 62a, the metal plate having opposing recessed or dished portions 65, 65a with dished end extensions 66, 66a. Dish-shaped part 6
5, 65a, extensions 66, 66a form an inlet chamber and an outlet chamber to form a central chamber 67 for exhaust gas. An elongated opening 68 in the extension 66 forms an inlet port and an elongated opening 69 in the opposite extension 6
6 forms an outlet port.

The pair of outer plates 71, 71a have a flange 72 that engages a flange 63 (see FIG. 5) and a flange 73 that engages a dished extension 66, 66a (see FIG. 6). , its outer plate is chamber 67
It has oppositely recessed portions or dished portions 74, 74a which cooperate with the dished portions 65, 65a to form a cooling fluid envelope therearound. As shown in FIG. 5, the walls 75 of the dished portions 65, 65a are arranged in the dished portions 74, 74a such that the side flanges 63 divide the fluid envelope into an upper portion 77 and a lower portion 78, respectively. an opening 79 is provided to communicate these two parts. A raised portion 80 is preferably formed on the outer plates 71, 71a so as to extend into the cooling fluid envelope.

The outer plate 71 has a fluid inlet conduit 81 formed in the dished portion 74 on one side of the central recess 82 and a fluid outlet conduit 83 adjacent the opposite side of the recess. A central laterally elongated recess 82 extends across the dish 74 and extends inwardly to abut and join the dish 65 of the inner plate 62. Recess 82 bisects upper envelope portion 77 to provide the desired flow pattern of fluid.

In use, the hot exhaust gas is transferred to the inlet port 6 of the inlet chamber.
8 and passes through a central chamber in which a plurality of bent metal plates 84 form a plurality of channels. The cooled gas flows into the outlet chamber and exits through port 69. Cooling fluid, such as water, enters upper envelope portion 77 via conduit 81 but is prevented from flowing directly to outlet conduit 83 by recess 82 . Fluid thus flows from the top to the lower envelope section through opening 79 at end 86, across section 78 to opening 87 at end 87, and enters upper envelope section 77 and exits via the outlet conduit. . Ribs or depressions 80 formed in the dished portions 74, 74a (see FIG. 5) prevent straight flow of fluid within the enclosure and disrupt the fluid to enhance heat transfer and increase cooling fluid flow. Prevents flow from channelling.

FIGS. 7-9 show another heat exchanger 91 that is the same as the heat exchanger shown in FIGS. 4-6 except for the positioning of the exhaust gas inlet and outlet. This heat exchanger 91 has a flange 93 around it.
recessed or dish-shaped portions 94, 94a located on both sides and forming a central chamber 95;
A pair of inner plates 92, 92a are used to limit the area. The outer metal plates 96, 96a have an outer peripheral flange 97 and recessed or dished portions 98, 98a on both sides. As shown in FIG. 8, an exhaust gas inlet 99 and an exhaust gas outlet 10
1 is formed through both plates 92, 96 brought together so that the plates form a conduit. A partially bent metal plate 102 is placed within chamber 95 to divide the flow of hot gas and enhance heat transfer to the cooling fluid within the envelope.

The gap between the dished portions forms a fluid envelope having an upper portion 103 and a lower portion 104. A long central recess or rib 105 is formed in the plate and engages the inner plate 92 to divide the upper bandage portion 103 into two chambers, with a fluid intake conduit 106 in the outer plate 96 on one side of the rib 105. one chamber and a fluid outlet conduit 107 communicates with the opposite chamber. A plurality of apertures 108 are formed in the flange 93 adjacent the conduit 106 and between the spaced walls of the dished portions 94, 94a and 98, 98a and
A set of openings are formed in flange 93 adjacent the outlet conduit. The flow of exhaust gas and cooling water is substantially in the same path as the heat exchanger 61.

Obviously in the embodiments of FIGS. 1-3, 4-6 and 7-9 the water connections are connected to the outer enclosure to provide the most effective distribution and circulation of the cooling fluid. Folded metal plates within the inner chamber, which may be positioned within the band, serve to divide the hot gas flow into smaller streams for effective heat transfer from the exhaust gases to the cooling fluid within the enclosure. The flow of cooling fluid may be co-flowing or counter-flowing with the flow of gas, with the cooling fluid jacket overlying the concentrated hot area. Although several embodiments and flow patterns are shown for illustrative purposes, the invention is not limited to what is shown.

The material selected for the heat exchanger has a high resistance to corrosion from corrosive exhaust gas environments and the preferred material is stainless steel, such as type 304 stainless steel.

As is clear from the above description, the heat exchanger according to the present invention is extremely compact, has a simple structure, has low flow resistance or pressure drop, has good thermal efficiency, and has the advantage of being inexpensive to manufacture.

[Brief explanation of the drawing]

1 is a perspective view of a first embodiment of the heat exchanger of the present invention, FIG. 2 is a sectional view taken along line 5--5 in FIG. 1, and FIG. 3 is a cross-sectional view taken along line 6 in FIG. 1. 4 is a top plan view of the second embodiment of the heat exchanger; FIG. 5 is a sectional view taken along line 8--8 of FIG. 4; Figure 6 is a partial cross-sectional view taken along line 9--9 in Figure 4, and Figure 7 is the third section of the heat exchanger.
FIG. 8 is a top plan view of the embodiment of FIG.
9 is a partial cross-sectional view taken along line 12--12 of FIG. 7. 32, 32a: Metal plate, 33, 33a: Peripheral flange, 34, 34a: Peripheral flange, 36, 3
6a: Dish-shaped portion, 43: Chamber, 47, 47a: Metal plate, 48, 48a: Peripheral flange, 49, 49
a: Peripheral flange, 52, 52a: Dish-shaped portion, 5
7: Surrounding zone, 65, 65a: Dish-shaped portion, 66, 6
6a: extension, 68: entrance, 69: exit, 80:
Ribs, 74, 74a: dish-shaped part, 77, 78: surrounding, 94, 94a: dish-shaped part, 98, 98a: dish-shaped part, 99: inlet, 101: outlet.

Claims (1)

[Claims] 1. A substantially flat heat exchanger made of two pairs of metal plates, the inner pair of metal plates forming a chamber and being joined by a peripheral flange and arranged facing each other. a chamber having an inlet and an outlet for receiving a first fluid, a heat transfer surface formed by at least one metal plate received within the chamber, and an outer pair of a metal plate having oppositely disposed dish-like portions and a peripheral flange substantially completely joined to the flange of said inner metal plate, said outer dish-like portion generally surrounding a chamber and having a second fluid therein; a fluid surround having an inlet and an outlet for receiving fluidic fluid in cooperation with said inner dish, wherein at least one pair of oppositely disposed side walls of said outer dish extends from a side wall of said inner dish. separated, the flange of the inner metal plate extending between the inner sidewall and the outer sidewall to divide the envelope into an upper portion and a lower portion and between the upper and lower envelope portions. has an opening for communication between the
said second fluid inlet and outlet are disposed in one outer dish, such that a central recess crosses the dish and divides the upper envelope portion into approximately equal halves between the inlet and the outlet; A two-fluid heat exchanger formed in the outer dish-shaped part. 2 A second fluid flow enters the inlet and corresponding half of the upper envelope section, passes through an opening in the inner flange adjacent the inlet, and passes through the lower envelope section to the opening in the inner flange on the opposite side of the heat exchanger. 2. A two-fluid heat exchanger as claimed in claim 1, in which the heat exchanger passes through the opposite half of the upper envelope section and exits from the outlet. 3 said first fluid inlet and outlet are disposed adjacent opposite ends of the heat exchanger in a pair of aligned side walls of the inner and outer dished portions and receiving said first fluid inlet and outlet; the inner and outer flanges of the sides of the heat exchanger are embossed around the inlet and outlet, the chamber having inlet and outlet portions aligned with the first fluid inlet and outlet; A two-fluid heat exchanger according to claim 1, wherein said partially folded metal sheet extends longitudinally between said inlet chamber portion and outlet chamber portion. 4. A two-fluid heat exchanger according to claim 3, wherein the raised portions of the inner and outer flanges are integrated into the inner and outer dish portions, respectively. 5. The inner dished portion is provided with a bilaterally disposed dished extension projecting beyond the outer flange, and the first fluid inlet and outlet are located in the extension. The two-fluid heat exchanger according to item 1. 6. Claim 5, wherein the inner dished extension is arranged on two parallel sides, and the two outer dished parts extend beyond the inner dished part on the two parallel sides. The two-fluid heat exchanger described in . 7. The two-fluid heat exchanger of claim 6, wherein the first fluid flow in the central chamber substantially crosses the second fluid flow in the outer envelope. 8. A two-fluid heat exchanger as claimed in claim 7, including a plurality of flow diverting ribs formed in said outer dish and extending into said fluid envelope portion. 9 said second fluid inlet and outlet are centrally located on one outer dish adjacent to a central recess, and said first fluid inlet and outlet are centrally located on one outer dish. and extending through the inner dish on either side of a central recess, defined by flared portions of the adjacent inner dish and outer dish, with the first fluid inlet and outlet being pleated to each other. A two-fluid heat exchanger according to claim 1. 10. The two-fluid heat exchanger of claim 1, wherein said heat exchange surface comprises a partially folded metal plate within said chamber and terminating near a pair of opposing ends.