EP1277945A1 - Cooler of an EGR system and EGR system with such a cooler - Google Patents

Abstract

The cooler (10) has a housing (12) formed with coolant inflow and outflow ports (16) and which encloses at least one by-pass pipe.

Description

Technical field

The invention relates to a cooler Exhaust gas recirculation system according to the preamble of claim 1 and an exhaust gas recirculation system with such a cooler.

In the field of engine technology it has been around for a long time Reduction of pollutant emissions known to the exhaust gas partly due to the fresh air side of the engine. Here it is dependent on the operating state of the Engine required to cool the exhaust gas. At the same time especially at low engine temperature and / or lower Engine load cooling of the exhaust gas may be undesirable. To for this purpose, a bypass is usually provided which Bypasses the cooler, using a suitable valve device To what extent the exhaust gas can be regulated through the bypass or the cooler flows.

State of the art

A cooler according to the preamble of claim 1 is known from the DE 197 33 964 A1 known. The cooler has a housing Connections for the supply and discharge of a coolant. Furthermore, a bypass tube is provided which the cooler bypasses the recirculated exhaust gas at least in part flows through the bypass tube and is not cooled.

Presentation of the invention

The invention has for its object a cooler Exhaust gas recirculation system and one equipped with it Exhaust gas recirculation system to create, in terms of his Construction is simplified.

This problem is solved by the cooler according to the Claim 1.

Accordingly, it is provided for the bypass tube that it is arranged within the housing, so to speak in the Housing of the cooler is integrated, so runs in this. In other words, the housing of the cooler forms which has the supply and discharge for the coolant, in particular the so-called casing tube of the cooler, the external boundary of the cooler. Outside of the case are in Area of the cooler only the supply and discharge lines for the Coolant provided. However, the bypass tube is not provided outside the housing or the casing tube, but integrated into it. The construction of the cooler will this considerably simplifies and the cooler can do less be made complex. In particular, a pleasant, compact appearance of the cooler, in its No additional lines in the environment, such as that Bypass pipe usually provided separately therefrom are.

Experiments have shown that the one to be achieved Effect, namely cooling the bypass tube to largely avoid flowing exhaust gas, if only by doing so can be achieved that the bypass tube is significantly different is designed as the cooling tubes. Although due to the Integration into the casing pipe of the cooler, within it the coolant, for example water, is one certain cooling of the bypass tube and its contents takes place, this cooling effect can be kept comparatively low if a single bypass tube with sufficient Cross section is provided, which is largely straight through extends the radiator. In contrast, the area that are flowed through by the exhaust gas for the purposes of cooling should be designed so that it branched numerous and accordingly has smaller tubes that are from the Coolant is washed around, so that the desired cooling effect entry. In addition, the cooling tubes can be compared to the Bypass tube can be extended, for example, by be designed to be coiled. This can on the one hand in the In case the exhaust gas flows through the cooling pipes, one sufficient cooling can be achieved, while at a Flow through the bypass tube, although this is located within the radiator jacket tube, the cooling effect largely avoided.

Preferred embodiments of the invention are in the further claims described.

In principle, it is preferred that the bypass tube is thermal is insulated so that the on the bypass tube acting cooling is comparatively low. A special one preferred embodiment is formed in that the Bypass tube is provided as a double-walled tube. By the The space between the two pipes occurs the desired Insulating effect.

This has particularly good properties in the case result in the one between the two walls double-walled tube a vacuum is formed. hereby can in particular the influence of convection of a medium, that is between the two tubes, switched off become. Furthermore, this embodiment can be particularly cheap with an advantageous manufacturing process for Combine cooler according to the invention by the bypass tube and preferably the entire cooler by vacuum soldering will be produced. The solder closes during this process so to speak the vacuum between the two walls of a double-walled bypass tube, so that without additional Manufacturing effort a thermally largely insulated Bypass tube can be produced, the invention can be integrated into the housing of the cooler and at the same time in use largely cooling the bypass pipe flowing exhaust gas prevented.

With regard to the supply and It is derivatives of the cooler according to the invention basically conceivable that the cooler on at least one Side has separate inlets and outlets. In this case would be the exhaust gas flow before reaching the cooler branched, and depending on the setting of an actuator the exhaust gas the supply of the cooling pipes or the bypass of the Reach cooler and then subjected to cooling be or not. In this case, the downstream end of the cooler a single drain be present because the lines described are still could unite within the cooler. Alternatively it is of course, conceivable that two derivatives exist are, and the flow paths behind the cooler unite. Furthermore, an actuator on the downstream Be provided end of the cooler. In this case it could upstream end of the cooler one or two leads have, depending on whether the exhaust gas flow before Cooler is branched or not. In any case, can also this embodiment by an actuator at the end of Cooler to ensure that the locked Flow path fills with exhaust gas at most, but not is flowed through, so that, for example, in the event that the bypass pipe is closed at the end, the cooling pipes are flowed through, and cooling of the exhaust gas takes place. Independent of the conceivable embodiments described it is currently preferred within the scope of the invention that the Cooler at least a single supply line and preferably above also has a single derivative. To the Flow paths, i.e. the bypass tube on the one hand and the Separating cooling pipes on the other hand is in the Cooler integrates an actuator in an advantageous manner serves to close at least the bypass tube. It is mentions that the actuator should always be provided can either the bypass tube or the cooling tube or closes the common supply line of several cooling pipes. However, tests have shown that in particular a suitable streamlined arrangement of the bypass get satisfactory results if only the bypass tube can be closed by the actuator. With in other words, the bypass tube is closed to a Flow through the cooling tubes and thus cooling the To reach exhaust gas. When the bypass tube is opened, most of the exhaust gas flows through the bypass pipe, while a comparatively small part of the exhaust gas continues to flow through the cooling tubes. Have measurements result that the exhaust gas is a matter of course also cools down slightly. For certain applications is the difference between the extent of cooling in this Case and the extent of cooling in the event that the Bypass tube is closed and only flows through the cooling tubes are, however, for influencing the temperature of the recirculated exhaust gas sufficient.

In view of the preferred in the cooler according to the invention integrated actuator there is an advantageous Embodiment in that the actuator is a flap. This flap can either be articulated at one end be in two different positions Bypass pipe or the supply line to the cooling pipes is closed. Alternatively, the valve can be in the form of a throttle valve be designed and articulated in a central area, so that, for example, only the bypass tube is lockable when closing the cooling tubes, such as explained above, is not absolutely necessary.

A single actuator that only for closing the Bypass tube is provided, in particular in that preferred embodiment sufficient, in which the Cooler a single supply line for the exhaust gas to be recycled has, and the bypass tube, fluidically considered, such as in the extension of the supply line considers that the "path of least resistance" for the Exhaust gas consists of flowing through the bypass pipe. in the Individual this means that if the supply line is central is arranged, the bypass tube can also be arranged centrally becomes. In other words, the bypass tube is just like that surrounding cooling pipes in such a way following a so-called Perforated plate formed that that passed into the cooler Exhaust gas with a comparatively low flow resistance meets the opening behind which the bypass pipe is located located so that the major part of the exhaust gas passes through this flows. In contrast, the exhaust gas hits in the Case where cooling is desired and the bypass pipe is closed by the actuator on the closed Opening and accordingly flows through the parallel arranged cooling pipes. However, the same effect can also apply to be obtained in the embodiment in which the Bypass tube not in the center of the cooler but on the edge is so inclined by the supply line in this case is designed so that the exhaust gas is initially inclined, in Essentially in the direction of the bypass tube in the cooler flows so that when the bypass tube is open it least resistance to flow through it. This is also a comparatively simple actuator, that only closes the bypass tube, sufficient. in the In this case, the rest would be that in the figures (cf. FIG. 3 and 4) recognizable cone, which is connected to the supply line of the Radiator connects, designed so that the Desired flow in the direction of the bypass tube, which turns on an edge is guaranteed. It is accordingly again mentioned that according to one preferred embodiment, the actuator is provided in this way is that it just closes the bypass.

The diameter of the cooler according to the invention, in particular its casing tube can be kept comparatively small, the required cooling effect is achieved if that Bypass tube is arranged largely centrally in the housing. If this arrangement with a largely central supply line combined, those can be cheap Flow conditions are guaranteed, as above executed, just closing the bypass required if the exhaust gas is to be cooled. If however, the cooler should be bypassed and the bypass pipe opened, the cooling tubes can remain open.

Although the cooler according to the invention is a single one Forms component of an exhaust gas recirculation system According to the invention provided that a complete Exhaust gas recirculation system is provided that the cooler according to the invention in one of the preceding described embodiments.

Finally, it should be mentioned that the invention also in one Process can be seen in which the bypass tube into the Housing, in particular the casing tube of a cooler integrated becomes. The bypass tube is preferably produced as a double-walled pipe Tube formed and at least the bypass tube, preferably the entire coolers are manufactured by vacuum soldering.

This can achieve the advantage that In a way, Lot froze the vacuum between the two Walls of the double-walled bypass tube is preserved, and the bypass tube thermally with very little effort can be trained in isolation.

Brief description of the drawings

Fig. 1

eine Seitenansicht des erfindungsgemäßen Kühlers;

Fig. 2

eine Querschnittsansicht des erfindungsgemäßen Kühlers;

Fig. 3

eine Längsschnittansicht des Zuleitungsbereichs des erfindungsgemäßen Kühlers in einer ersten Stellung eines Stellorgans;

Fig. 4

eine Längsschnittansicht des Zuleitungsbereichs des erfindungsgemäßen Kühlers in einer zweiten Stellung eines Stellorgans;

Fig. 5

eine Querschnittsansicht einer zweiten Ausführungsform des erfindungsgemäßen Kühlers; und

Fig. 6

eine Längsschnittansicht des Zuleitungsbereichs des erfindungsgemäßen Kühlers gemäß der zweiten Ausführungsform.

The invention is explained in more detail below on the basis of exemplary embodiments illustrated in the drawings. Show it:

Fig. 1

a side view of the cooler according to the invention;

Fig. 2

a cross-sectional view of the cooler according to the invention;

Fig. 3

a longitudinal sectional view of the supply area of the cooler according to the invention in a first position of an actuator;

Fig. 4

a longitudinal sectional view of the supply area of the cooler according to the invention in a second position of an actuator;

Fig. 5

a cross-sectional view of a second embodiment of the cooler according to the invention; and

Fig. 6

a longitudinal sectional view of the supply area of the cooler according to the invention according to the second embodiment.

Detailed description of preferred embodiments of the invention

1 is the cooler 10 according to the invention a side view. The cooler 10 has a Housing 12 in the form of a jacket tube. On the two Flanges 14 are provided at the ends of the housing for this purpose serve the cooler according to the invention before and after to connect horizontal sections of an exhaust gas recirculation system. Extend through the casing tube 12, as follows is executed more precisely, at least one bypass tube and at least one cooling pipe. Accordingly, how 1 can already be seen from the side view of FIG. 1, no pipes outside the casing pipe 12 of the cooler. Rather, the bypass tube in particular is in the casing tube 12 of the cooler integrated. The jacket tube 12 of the cooler is on its ends sealed so that inside it over a supply or discharge line 16 coolant, for example water, can be passed through, all through the Jacket tube 12 washed around extending tubes. This will especially the cooling pipes and their contents are cooled so that the exhaust gas flowing through it is cooled. That too Bypass tube is cooled. However, this is due of the measures described in more detail below less extensive than in the event that the exhaust gas through the Cooling pipes flow, so that the cooler in the sense of a bypass can be avoided.

From Fig. 2, the internal structure of the cooler 10 and Contents of his casing tube 12 preferred for a first Embodiment out. Largely centrally in the casing tube 12 is the bypass tube 18, which in the case shown is provided as a double-walled tube, with between a vacuum is located on the two walls. Through this thermal Isolation as well as the fact that the Bypass tube around a largely straight through the jacket tube 12 extends pipe, experiences exhaust gas when it passes through the bypass tube 18 flows, a comparatively small Cooling. In contrast, in the area of the Bypass tube 18 provided numerous cooling tubes 20, the Branches of a preferably central cooling pipe feed line represent. Simply because of the fact that numerous Cooling tubes 20 are present, which have a smaller cross section have than the bypass tube 18 and beyond are thermally insulated in the event that the exhaust gas flows through the cooling tubes 20, the desired cooling effect on. In addition, the cooling tubes, which is not the case in FIG. 2 recognize is to be coiled so that they be extended. This will make the Exhaust gas in the cooling pipes increases and there can be one extensive cooling occur.

3 is for the inflow area of the embodiment 1 and 2 of the cooler as shown in the cooler Actuator in the form of a rotatable throttle valve 22 is integrated. The integration of the actuator 22 in the Cooler means that the cooler has a single supply line 24 through which the exhaust gas to be returned to the cooler is directed. In the area of the cooler shown in FIG. 3 the branching takes place between the largely central arranged bypass tube 18 and the immediate cooling area, the numerous in the area of the casing tube 12 Cooling tubes 20 is formed. According to the shown Embodiment is the actuator 22 largely in shape a throttle valve is provided, one in its the central region of the center of rotation is rotatable in such a way that the bypass tube 18 by an orientation of the Throttle valve 22 in the flow direction, as shown in FIG. 3, can be opened. It should be noted that this Embodiment also in the event that the bypass tube 18 is opened, the surrounding cooling area as well as the Cooling tubes 20 remain open. Since the bypass tube 18 but largely located centrally in the casing tube 12, the exhaust gas to be recycled mainly flows through the Bypass tube 18 and undergoes extremely little cooling. The Temperature of the comparatively small amount of exhaust gas, which flows through the cooling pipes, this is to a small extent reduced, so that no significant cooling occurs, such as this by opening the bypass and thus achieved Bypassing the cooler is desirable.

4 is the closed position of the throttle valve 22 shown, in which the throttle valve 22 the bypass tube 18th closes. In this position, all of the exhaust gas flows through the cooling tubes 20 and the desired cooling takes place of the recirculated exhaust gas. It should be mentioned that by any intermediate positions of the throttle valve 12 between The positions shown in Figs. 3 and 4 regulate the Flow through the bypass and thus the The temperature of the recirculated exhaust gas is reduced can.

In Fig. 5 is an alternative embodiment in cross section of the inventive cooler shown. In this case the bypass tube 18 is not centrally located in the jacket tube 12 but on the edge. The rest of the casing tube 12 is taken up by cooling tubes 20. The mode of action is essentially the same as the previous one described embodiment, except that the Supply area is to be designed differently.

This is shown in Figure 6. As this illustration clearly the embodiment of FIG. 5 is suitable in particular for a modification of the actuator by which either the bypass tube 18 or the cooling tubes 20 are closed should be. In other words, be different 3 and 4, the cooling tubes 20 closed when the bypass tube 18 is open. this will 6 by a flap reached that at its end in a range between the Bypass tube 18 and a common supply area for the Cooling tubes 20 is arranged foldable. 6 position shown, the bypass tube 18 is closed. In the alternative position when the flap 22 is folded down is the common supply area for the cooling pipes locked. Finally, it should be mentioned that the Embodiment of an actuator 22 according to FIG. 6 also with a cooler cross section according to FIG. 2 can be combined. Here, the bypass tube 18 is at the beginning of the Radiator, essentially the part shown in FIG. 6 is so curved that it is towards the center of the Jacket tube 12 is sufficient and thus in the further course of Jacket tube 12 approximately centrally through this extends.

Claims (8)

Cooler (10) of an exhaust gas recirculation system, with: a housing (12) with connections (16) for supplying and removing coolant, at least one bypass tube (18), characterized in that
the bypass tube (18) is arranged inside the housing (12). Cooler according to claim 1,
characterized in that
the bypass tube (18) is a double-walled tube. Cooler according to claim 2,
characterized in that
a vacuum is formed between the two walls of the double-walled tube (18). Cooler according to at least one of the preceding claims,
characterized in that
the cooler has a single inlet and / or outlet for the exhaust gas to be returned and an actuator (22) for closing at least the bypass pipe (18). Cooler according to claim 4,
characterized in that
the actuator is a flap (22). Cooler according to at least one of the preceding claims,
characterized in that
the cooler has a single supply line for the exhaust gas to be returned, and the bypass pipe (18) is, in terms of flow technology, in the extension of the supply line. Cooler according to at least one of the preceding claims,
characterized in that
the bypass tube (18) is arranged largely centrally in the housing (12). Exhaust gas recirculation system with at least one cooler (10) at least one of the preceding claims.

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