WO2004042310A1

WO2004042310A1 - Multiple-fluid heat exchanger, in particular for a motor vehicle, and related thermal energy management system

Info

Publication number: WO2004042310A1
Application number: PCT/FR2003/003237
Authority: WO
Inventors: Ngy Srun Ap
Original assignee: Valeo Thermique Moteur
Priority date: 2002-10-30
Filing date: 2003-10-30
Publication date: 2004-05-21
Also published as: FR2846735B1; AU2003288346A1; FR2846735A1

Abstract

The invention concerns a heat exchanger (2), in particular for a motor vehicle, enabling heat exchange between a first, a second and a third fluid, for example gearbox and/or engine oil (44), exhaust gases and engine coolant. The exchanger may comprise a central housing (23) wherein the first and second fluids flow while exchanging heat and a peripheral casing (34) concentric to the central housing (23) and wherein flows the third fluid. The central housing (23) may comprise a bundle of parallel tubes (10) whereof the outer peripheral wall defines, with a cylindrical shell (4) a chamber (12) for the first fluid (F1, F2), the second fluid (F3, F4) flowing inside the tubes (10).

Description

Heat exchanger with several fluids, in particular for a motor vehicle, and associated thermal energy management system.

The invention relates to the field of heat exchangers, in particular for motor vehicles, for the exchange of heat between heat transfer fluids.

Today's motor vehicles include an increasing number of heat exchangers. Indeed, in addition to the traditional functions of engine cooling and heating and air conditioning of the passenger compartment, increased requirements in terms of. comfort or compliance with strict environmental standards lead to heating or cooling certain fluids to adapt their temperature, in order to allow improved management of the thermal energy developed by the internal combustion engine.

Thus, in the cold start phase of the engine, it is desirable to accelerate the rise in temperature of the engine oil and / or of the gearbox. Likewise, it is desirable to allow a rapid rise in temperature of the water temperature of the engine cooling circuit. Furthermore, at normal or high engine load, it is desirable to cool the exhaust gases in order, inter alia, to increase the life of the catalytic elements used to trap nitrogen oxides and reduce pollutant emissions. in the air. Finally, at normal or high engine load, the engine and gearbox oil must be cooled, usually by exchange with the engine cooling water.

In the state of the art currently known, all these heat exchange functions are fulfilled by exchangers heat in which the fluids to be heated or cooled exchange heat in pairs. A large number of separate exchangers is therefore necessary to fulfill all of the desired functions. These exchangers occupy a large volume under the engine hood. They require the presence of numerous supply and evacuation fluids.

The present invention relates to a heat exchanger, in particular for a motor vehicle, which overcomes these drawbacks.

These objects are achieved according to the invention, in that ^"T exchanger comprises means for heat exchange between a first, a second and a third fluid.

These fluids can be in the liquid, gaseous state or in the form of liquid and gaseous phases. The exchanger can be of any type, for example with plates or tubes. It can operate with a simultaneous circulation of the three fluids or with different combinations of fluids, exchanging heat in pairs.

In a preferred embodiment, the first fluid consists of the oil of the gearbox and / or the engine, the second fluid by the exhaust gases and the third fluid by the engine cooling water.

Thanks to these characteristics, it is possible to accelerate the temperature rise of the engine oil and / or the gearbox by recovering the heat from the exhaust gases. This results in a decrease in the fuel consumption of the engine. Furthermore, at low load, the exchanger of the invention makes it possible to maintain the temperature of the engine oil and / or of the gearbox at a higher temperature than that of the engine cooling water used. in the exchangers of the prior art. This allows a further reduction in the fuel consumption of the engine. Similarly, the exchanger of the invention makes it possible to accelerate the rise in engine water temperature in the event of a cold start by recovery of the thermal energy of the exhaust gases.

At nominal or heavy load of the vehicle engine, the exhaust gases can be cooled, for example to a temperature between 250 ° C and 450 ° C, which improves the efficiency of the catalysis elements of type " DeNox ”used to trap nitrogen oxides in exhaust gases.

Finally, when the engine is fully loaded, the oil can be cooled in a conventional manner by the engine cooling water.

In a particular embodiment, the exchanger comprises a central housing in which the first and the second heat transfer fluid circulate by exchanging heat and a peripheral envelope concentric with the housing in which the third fluid circulates.

Advantageously, the central housing has a cylindrical peripheral wall provided with inlet and outlet pipes for the first fluid and two end walls; a bundle of tubes elongated parallel to the axis of the housing, the end regions of each tube passing fluid-proof openings formed in said end walls, and the external faces of the tubes delimiting inside the housing a chamber for the circulation of the first fluid; and two annular cups of revolution respectively covering the two ends of the housing and sealingly linked to the periphery thereof, to define with the end walls of the manifolds which communicate with each other by means of tubes for the circulation of the second fluid.

Preferably, at least one of the cups has at its axial end turned away from the housing a cylindrical portion defining an axial inlet or outlet manifold for the second fluid.

There may also be provided inlet and / or outlet pipes for the third fluid, cooperating with the envelope in which said third fluid circulates. The inlet and / or outlet pipes for the first fluid and / or the third fluid are, for example, oriented in orthogonal, in particular radial, directions relative to

^'~ L ^~ "axis" longitudinal ^"of ^the" central housing. It thus optimizes the size of the exchanger.

Furthermore, the invention relates to a thermal energy management system developed by a heat engine, in particular for a motor vehicle. This management system comprises a thermal engine, a cooling circuit for the thermal engine including a main radiator in which a heat-transfer fluid circulates, a heating circuit including a heater, a cooling circuit for the engine oil and / or the gearbox, an engine exhaust gas cooling system. It includes a three-fluid exchanger according to the present invention.

In one embodiment of the management system, the exchanger is mounted on a bypass of an exhaust pipe coming from the heat engine. In this case, it is advantageous to provide a valve interposed on the exhaust pipe to circulate the exhaust gases selectively in the exhaust pipe and / or in the bypass and the exchanger.

In another embodiment of the management system, the exchanger is mounted on an exhaust gas recirculation pipe interposed between the exhaust and the intake of the heat engine.

According to another characteristic of the invention, the heating circuit comprises a three-way valve or a three-way thermostat for bringing the fluid from the heating circuit directly to the heat engine or for passing this fluid through the exchanger.

Other characteristics and advantages of the present invention will appear on reading the following description of exemplary embodiments given by way of illustration with reference to the appended figures. In these figures:

- Figure 1 is a longitudinal sectional view of a preferred embodiment of a three-fluid exchanger according to the present invention;

- Figure 2 is a schematic view of a thermal energy management system developed by an engine comprising an exchanger according to the invention in cold start configuration or city traffic;

- Figure 3 shows the thermal energy management system of Figure 2 in normal engine configuration;

- Figure 4 shows the same system in operating configuration at full load of the engine;

- Figure 5 is a diagram showing the exhaust gas circuit in cold start configuration and city traffic;

- Figure 6 shows the exhaust gas circuit at full load of the engine; and

FIG. 7 is a schematic view of another management system which constitutes a variant of that of FIGS. 2 to 4. In FIG. 1, the exchanger designated by the general reference 2 comprises a cylindrical wall 4 of axis XX made, for example, from rolled and welded sheet metal. The peripheral wall 4 constitutes a cylinder which is closed at a first end by an end wall 6 and at a second end by an end wall 8. Each of the end walls 6 and 8 is perforated with regularly distributed cylindrical holes , in which are housed the ends of tubes 10 forming a parallel bundle.

The internal wall of the cylinder 4 delimited with the external wall of the tubes 10 a chamber 12 for the circulation of a first fluid. For this purpose, the cylindrical wall 4 is equipped with a

^" inlet pipe 14 and ^" d ^~ '^" unë ^"" outlet pipe 16 ^' for ^" this first fluid, for example the engine or gearbox oil (arrows FI, F2). Ferrules 18 are advantageously provided in the cylindrical wall 14 to receive the inlet pipes 14 and outlet 16, and drain the solder allowing a tight connection of the pipes to the peripheral wall 4.

At its first end, the cylindrical wall 4 has an annular cup of revolution 20 and, at its second end, an annular cup of revolution 22. The cups 20 and 22 are tightly connected to the cylindrical casing 4 to define respectively with the end walls 6 and 8 of the manifolds 24 and 26 which communicate with each other by means of the tubes 10 for the circulation of the second fluid, for example the vehicle exhaust gases (arrows F3, F4). An inlet pipe 28 is provided on the cup 20 and an outlet pipe 30 on the cup 22. Each of the pipes 28 and 30 has a fixing flange 32 making it possible to connect it respectively to a supply pipe and to a pipe. second fluid exhaust.

Finally, the exchanger 2 comprises a cylindrical shell 34 which surrounds the peripheral wall 4 so as to provide an annular space 36 between these two walls constituting a chamber for the third fluid, for example the engine cooling water. An inlet pipe 38 and an outlet pipe 40 are provided on the shell 34 to allow the entry and exit of the third fluid respectively. The shell 34 is tightly linked to the annular cups of revolution 20 and 22.

The peripheral wall 4 containing the bundle of parallel tubes 10 constitutes, with the cups 20 and 22, a central housing 23 in which the first and the second fluid circulate by exchanging heat. The shell 34 constitutes a ^" wrapped ^" peripheral ^" concentric with the housing 23, ^""" in which the third fluid circulates (arrows F5, F6). The third can thus exchange heat with the first fluid (arrows FI, F2).

FIGS. 2 to 4 show three diagrams of a thermal energy management system developed by a motor vehicle engine 44. The system comprises a circuit 46 for cooling the engine. This circuit includes a main cooling radiator 48, disposed at the front of the vehicle, and a water pump 50, electric or mechanical, which circulates the water in the circuit 46. A fan unit 52 attached to the main cooling radiator 48 makes it possible to force the circulation of air through the radiator tubes when the vehicle is not traveling at a sufficient speed, for example in congestion. A thermostat 54 makes it possible to control the circulation of water in the circuit 46. An expansion tank 56 makes it possible to absorb the expansions of the liquid when its temperature increases.

The thermal energy management system also comprises a heating circuit 58 comprising a radiator for heating the passenger compartment of the vehicle 60, also called an air heater. A three-way valve or a three-way thermostat 62 makes it possible to bring the cooling fluid from the heating circuit directly to the engine 44 via a pipe 64, or to pass it through the exchanger 2 by means of line 66.

The system also includes a circuit for cooling the oil of the engine 44 or of the gearbox (not shown) of the engine 44. In the example, the engine 44 comprises an oil sump 70 connected to the exchanger 2 by a pipe 72 and a pipe 74.

The inputs and outputs for the three fluids are designated by the same arrows as ^" in ^" Figure 1, ^" namely: - arrows FI and F2 for the first fluid (oil, in the example);

- arrows F3 and F4 for the second fluid (exhaust gas, in the example); and arrows F5 and F6 for the third fluid (cooling water, in the example).

FIGS. 5 and 6 show the detail of the circuit 76 for cooling the exhaust gases from the engine 44. It comprises a catalytic converter 78, and a catalytic converter 80, commonly called “DeNox pot”, the function of which is is to trap nitrogen oxides. A valve 82 is interposed between the catalytic converter 78 and the catalytic converter 80 on an exhaust pipe 84 coming from the engine 44. In an alternative embodiment, the valve 82 could be replaced by a three-way valve 83 shown in dashed lines . The three-fluid exchanger 2 of the invention is mounted on a branch 86 of the exhaust pipe 84.

In Figures 2 and 5, the thermal energy management system has been shown in cold start position and city traffic. In such a configuration, it is necessary to shorten as much as possible the rise in temperature of the system fluids, in particular of the engine cooling water and of the engine and gearbox oil. The three-way valve or thermostat 62, electric or pneumatic, closes the water flow in the exchanger 2. All the flow of the heating liquid which has passed through the air heater returns directly to the engine 44. All of the gases exhaust passes through the exchanger 2. For this purpose, the valve 82 is closed. The heat from the exhaust gases is thus recovered. The engine oil, instead of being cooled, is thus heated, which makes it possible to accelerate its rise in temperature and to reduce the fuel consumption of the engine 44.

In normal operation of the engine, that is to say at medium load, the thermostat or the three-way valve 62 lets part of the water flow from the heating circuit 58 pass through the three-fluid exchanger 2, l other part returning directly to the engine via line 64. The cooling water allows the engine oil temperature to be moderately cooled. The valve 82 or the three-way valve 83 can be closed (Figure 5), so that all of the exhaust gases pass through the exchanger. This allows them to cool and, therefore, improves the efficiency of the catalytic converter 80 or, alternatively, the three-way valve could distribute the circulation of gases selectively between the exhaust pipe 84 and the bypass 86 .

FIGS. 4 and 6 show the engine energy management system 44 in a full engine load configuration. The three-way valve 62 is closed, so that all of the cooling fluid of the heating circuit 58 passes through the exchanger 2 before returning to the engine 44. This characteristic makes it possible to cool the engine oil. Furthermore, the valve 82 (or alternatively the valve 83) is in the open position, so that the largest part of the exhaust gases avoids the exchanger 2. The heat exchange of the exhaust gases to the engine oil is thus reduced or eliminated. The exchanger 2 thus functions as an exchanger with two fluids (water and oil) which ensures the cooling of the engine oil like a conventional exchanger.

The management system of Figure 7 is similar to that of Figures 2 to 4, the common elements being designated by the same reference numerals. The exchanger 2 is here mounted, not a bypass of the exhaust pipe, but on an exhaust gas recirculation pipe 90. This pipe 90 is interposed between the exhaust 92 and the intake 94 of the heat engine 44 to return to Y admission o_Q ^~ mδt ^{^"ine"} part ^{^"of"} s gas ^"cl exhaust and burn again. the pipe 90 constitutes what is commonly called the line" EGR "(short for" Exhaust Gas Recirculation ”, an English expression meaning“ exhaust gas recirculation ”).

Apart from this difference, the operation of the management system of Figure 7 is similar to that of Figures 2 to 4.

The heat exchanger of the invention is capable of numerous variant embodiments.

Claims

claims

1. Heat exchanger, in particular for a motor vehicle, for the heat exchange between fluids, characterized in that it means for heat exchange (23, 10, 34) between a first, a second and a third fluid.

2. Exchanger according to claim 1, characterized in that the first fluid consists of the engine oil and / or the gearbox oil, the second fluid by the engine exhaust gases and the third fluid by the engine cooling water (44).

^~ 3. Exchanger ^~ sel-on ^__ la -revendication 1- or ~ 2, characterized in that it comprises a central housing (23) in which the first and the second fluid circulate by exchanging heat and a peripheral envelope ( 34) concentric to the housing (23) in which the third fluid circulates.

4. Exchanger according to one of claims 1 to 3, characterized in that the central housing (23) has a peripheral wall (4) provided with inlet and outlet pipes (14, 16) for the first fluid (FI , F2) and by two end walls (6, 8), a bundle of elongated tubes (10), the end regions of each tube (10) passing fluid-tight openings in the walls of end (6, 8), and the external faces of the tubes delimiting inside the housing a chamber (12) for the circulation of the first fluid, and two annular cups (20, 22) of revolution respectively covering the two ends of the housing and tightly linked to the periphery of the latter to define manifolds which communicate with each other via the tubes (10) for the circulation of the second fluid.

5. Exchanger according to claim 4, characterized in that at least one of the cups (20, 22) has, at its axial end opposite the housing, a cylindrical portion (28, 30) defining an axial inlet or outlet manifold for the second fluid (F ₃ , F ₄ ).

6. A thermal energy management system developed by a heat engine (44) of a motor vehicle, comprising a heat engine (44), a cooling circuit (46) of the heat engine (44) including a main radiator (48) in which a heat transfer fluid circulates, a heating circuit (58) including an air heater (60), a cooling circuit (68) of the engine oil (44) and / or of the gearbox, a cooling circuit engine exhaust gas (44), characterized in that it comprises an exchanger (2) according to one of claims 1 to 5.

7. Management system according to claim 6, characterized in that the exchanger (2) is mounted on a bypass (86) of an exhaust pipe (84) from the heat engine (44).

8. Management system according to claim 7, characterized in that it comprises a valve (82) interposed on the exhaust pipe (84) for circulating the exhaust gases selectively in the exhaust pipe ( 84) and / or in the bypass (86) and the exchanger (2).

9. Management system according to claim 6, characterized in that the exchanger (2) is mounted on an exhaust gas recirculation pipe (90) interposed between the exhaust (92) and the intake (94) of the heat engine (44).

10. Management system according to one of claims 6 to 9, characterized in that the heating circuit (58) comprises a three-way valve or a three-way thermostat (62) for bringing the fluid from the heating circuit directly to the engine thermal (44) or pass this fluid through the exchanger (2).