EP1857761A2 - Heat exchange device for combustion engines - Google Patents

Abstract

The unit has a housing (1) in which channels (2, 3), which are streamed by respective fluids that are to be cooled, are arranged, where a third channel (4) streamed by a cooling unit is arranged in the housing. A by-pass channel (5) for the fluid that is to be cooled is arranged in the housing. One of the channels is by-passed by the by-pass channel. The fluid mass flow into the by-pass channel and the channel (2) is controlled by a control device.

Description

The invention relates to a heat transfer unit for internal combustion engines with a housing in which at least a first channel through which a fluid to be cooled is arranged, at least one channel through which a second fluid can pass and at least one channel through which a coolant can pass, and a heat transfer unit for the oil circuit of an internal combustion engine with an oil-permeable channel and at least one channel through which a coolant can flow, wherein the oil-permeable channel is in heat-conducting contact with the channel through which the coolant can flow.

Such combined heat transfer units are known from the prior art and are used, for example, to cool in a unit both the charge air and an exhaust gas flow, or to arrange, for example, a lubricating oil cooling either individually or in a housing with a charge air cooling or exhaust gas cooling. By cooling the exhaust gas or the charge air, the combustion temperature is lowered, which in turn can reduce the proportion of nitrogen oxides in the exhaust gas.

So will in the DE 197 22 256 C1 a heat transfer unit proposed in which an exhaust gas cooler and an oil cooler are arranged in a common housing and are separated by a cooling water channel. In this way, both cooling of the exhaust gas and the lubricating oil after warming up of the internal combustion engine can be achieved in a confined space.

Furthermore, it is known that in the warm-up phase of the internal combustion engine, a high pollutant content arises, which is why in modern internal combustion engines often bypassing the exhaust gas cooler bypass channel is formed, with the aid of a faster heating of the internal combustion engine is achieved by the uncooled recirculated exhaust gas.

For example, in the DE 102 03 003 A1 discloses an exhaust gas heat exchanger having in a housing both the exhaust gas cooling device and a bypass device bypassing the cooling device. Depending on the operating state of the internal combustion engine, the exhaust gas flow is conducted either through the cooling device or via the bypass channel via an upstream bypass flap.

In this way it becomes possible to carry out a temperature management in the internal combustion engine, whereby a faster heating of the internal combustion engine is realized. Furthermore, after the warm-up phase to reduce the emitted pollutants, a temperature control of the recirculated exhaust gas and thus also the combustion temperatures can be realized.

However, there is still the problem of despite the existing bypass relatively long warm-up, especially in low heat generating turbo diesel engines. In particular, there are problems with integrated heat exchangers such as in the oil-gas heat exchanger of DE 197 22 256 C1 in which the warm-up phase can not be shortened in comparison to known designs, since the oil cooler is constantly surrounded by coolant.

The object of the invention is therefore to provide a heat transfer unit with which an effective temperature management can be operated in the internal combustion engine, at the same time the space requirement should be minimized. In a special application for the oil circuit of an internal combustion engine is to be completely dispensed with the heater currently used in turbo diesel engines. This should be further reduced in comparison to known embodiments, the high pollutant content generating warm-up phase.

This object is achieved in that in the housing a bypass channel for the first fluid to be cooled is formed, via which the at least one first channel through which the first fluid to be cooled can be bypassed. In this way, in the heat transfer unit in a small space temperature control is also possible in a combined cooler.

In the specific case of a heat transfer unit for the oil circuit of an internal combustion engine, this object is achieved in that in the heat transfer unit an exhaust gas flow-through channel is formed, which is also in heat conductive contact to the oil flow channel, so that rapid heating of the oil through the warm exhaust gas flow is reached. Preferably, the exhaust gas through-flowable channel is a bypass channel of an exhaust gas cooler.

In a preferred refinement, the at least one channel through which the second fluid can flow is arranged between the bypass channel and the channel which can be flowed through by the coolant. This ensures that depending on the flow through the bypass channel and the coolant flow-through channel, the second fluid can either be heated or cooled either.

In an advantageous embodiment, the fluid mass flow of the first fluid to be cooled in the bypass channel and the first channel through which the first fluid to be cooled can be controlled via at least one control device. Thus, temperature control of both the first fluid to be cooled and the second fluid becomes possible.

In a preferred embodiment, the fluid mass flow of the first fluid to be cooled in the bypass channel and the first channel through which the first fluid to flow to be controlled via two valves, of which the first valve in the region of an exhaust gas inlet nozzle in the housing before the first channel to be cooled by the fluid to be cooled is arranged and the second valve is arranged in the region of the exhaust gas inlet nozzle in the housing in front of the bypass channel. Such valves may be formed, for example, flap-shaped and electromotive Adjustment units are dependent or independently regulated. A temperature control is thus easily possible.

An optimal heat transfer between the media is achieved in that the channel through which the coolant can flow has a first common partition wall with the channel through which the first fluid to be cooled flows and a second common partition wall with the channel through which the second fluid can flow. The two common partitions thus serve directly as thermal bridges between the media.

Such a likewise improved heat transfer for faster temperature increase of the second fluid results when the bypass channel has a common partition wall with the channel through which the second fluid can flow. Thus, if the first fluid has a higher temperature than the second fluid, heating of the second fluid will occur when the bypass channel flows through.

In a preferred embodiment, the channel through which the coolant can flow completely surrounds the channel through which the first fluid to be cooled can flow. This ensures optimized cooling of the first fluid to be cooled.

Preferably, ribs protrude into at least one of the channels of at least one of the partitions. These also significantly improve the heat transfer between the media. In particular, with formation of the ribs in the gas-conducting channels, this results in great advantages in terms of heat transfer. Both continuous ribs along the flow direction are conceivable as well as interrupted single ribs.

In a further embodiment, the coolant flow is controllable via a control device, so that it can be completely exhibited during the warm-up phase, whereby a much faster heating of the second fluid can be achieved.

This advantage can also be enhanced by additionally controlling the fluid mass flow of the second fluid via a control direction.

In a preferred application, the first fluid to be cooled is exhaust and the second fluid is oil. This means that in the cold start phase, the exhaust gas flow through channel is bypassed and the exhaust gas flowing through the bypass channel can be used for faster heating of the oil in the combined heat transfer unit. At full load, the coolant can be used both for cooling the exhaust gas and for cooling the oil in the heat transfer unit.

In an embodiment that can be produced cost-effectively, the heat transfer unit is produced from die-cast parts which are connected to one another by friction stir welding.

For further space reduction, the heat transfer unit can be at least partially integrated into the cylinder head.

It is clear that an optimal temperature management of the internal combustion engine is possible by a heat transfer unit constructed in this way and the heating phase of the internal combustion engine can be significantly reduced in comparison to known embodiments. In addition, the heater can be omitted in turbodiesel engines. With the invention, these advantages are realized in the smallest space and at low cost.

• Figur 1 zeigt einen Querschnitt durch eine erfindungsgemäße Wärmeübertragungseinheit in geschnittener Darstellung.
• Figur 2 zeigt einen Längsschnitt durch die erfindungsgemäße Wärmeübertragungseinheit der Figur 1 im Bereich des Einlasses.

An embodiment is shown in the drawings and will be described below.

• Figure 1 shows a cross section through a heat transfer unit according to the invention in a sectional view.
• FIG. 2 shows a longitudinal section through the heat transfer unit according to the invention of FIG. 1 in the region of the inlet.

For better understanding, the exemplary embodiment according to FIGS. 1 and 2 is explained with reference to an exemplary embodiment in which exhaust gas is used as the first fluid to be cooled and as second fluid oil, so that the heat transfer unit is a combined exhaust / oil heat transfer unit , However, such a heat transfer unit can also be used for other cooling combinations.

According to FIG. 1, the heat transfer unit according to the invention consists of a housing 1 which surrounds the heat transfer unit and defines it to the outside, which housing can be designed in one or more parts. In the housing 1, a first through-flow of exhaust gas channel 2 is formed. Furthermore, a channel 3 through which oil can flow is arranged in the housing 1, which passage 2 can be traversed by a coolant-flow channel 4, wherein the coolant flow-through channel 4 is designed such that it completely surrounds the exhaust gas flow channel 2 in cross section , At the side facing away from the coolant channel 4 of the oil flow-through channel 3, a bypass channel 5 is arranged, which is also flowed through by exhaust gas.

The individual channels 2, 3, 4, 5 are each separated from each other via common partitions, so that a first common partition 6 between the coolant flow-through channel 4 and the exhaust gas permeable channel 2 is arranged, a second common partition 7 between the coolant flow channel 4 and the oil-permeable channel 3 is arranged and a third common partition wall 8 between the bypass channel 5 and the oil-flow channel 3 is arranged. In this way, different heat exchanger surfaces between the different media are realized. Thus, a heat exchange via the common partition wall 8 between the exhaust gas and oil, via the partition wall 7 between the oil and the coolant and via the partition wall 6 between the exhaust gas and the coolant.

In the channels 2, 3, 5 extend in the main flow direction extending ribs 9, which can be carried out both as a one-piece longitudinal rib as well as a plurality one behind the other and adjacent single ribs can be performed. These ribs 9 protrude in the present embodiment, both in the bypass channel 5 and in the oil-flowed channel 3 and the exhaust gas flowed through channel 2, both in the exhaust gas flowed through channel 2 as well as in the oil flow channel 3 protrude the ribs of two opposite sides , This means for the exhaust gas-permeable channel 2 a significant improvement in the heat transfer, as is significantly improved on the two-sided ribbing of the heat transfer through the surrounding coolant. For the region of the oil-permeable channel 3, the ribbing means that both the heat transfer from the coolant to the oil is improved by the ribs 9 formed on the dividing wall 7 and the heat transfer by the ribs 9 formed on the dividing wall 8 can be improved by the bypass duct 5 ,

Furthermore, it can be seen that the coolant flow-through channel 4 has an inlet connection shown in FIG. 1, which in the present exemplary embodiment is arranged laterally in the front region of the heat transfer unit and via which the coolant flows through the channel 4 which can flow through the coolant. Of course, a corresponding unillustrated coolant outlet pipe is present in the rear region of the heat exchanger unit. In the region of the coolant inlet nozzle 10, a coolant regulating device 11 is additionally designed in the form of a control valve, via which the coolant flow can be controlled.

Also, the oil flow-through channel 3 has in the present example, a laterally arranged oil inlet nozzle 12, in turn, on the opposite side, ie in the rear region of the oil-permeable channel 3, a corresponding outlet nozzle is arranged. Again, in the area of the oil inlet nozzle 12, a control device 13 for controlling the flow rate of the oil in the form of a control valve is arranged.

FIG. 2 shows the inlet region in the form of an exhaust gas inlet nozzle 14 for the heat transfer unit. In the area of the exhaust inlet connection 14, a first control device 15 in the form of a flap valve and a second control device 16 in the form of a flap valve are formed. These are arranged in each case in that the exhaust gas flow-through channel 2 can be closed by the first flap 15 and the second bypass channel 5, also through which exhaust gas can flow, through the second flap 16. These two flaps 15, 16 can be regulated either independently or independently of each other, depending on whether only a temperature control or an exhaust quantity control is to be realized.

The oil flow-through channel is closed at its end facing the exhaust gas inlet port 14 by a wall 17. This wall 17 and connected to the wall 17 partitions 6 and 8 divide seen in the flow direction of the exhaust gas heat exchanger unit in the region of the exhaust inlet nozzle 14 in the exhaust gas leading channels 2 and 5. Accordingly, the partition 6 and the housing 1 serve as abutment surfaces for the flap 15 to the closure of the channel 2 and the wall 17 and the housing 1 as abutment surfaces for the flap 16 for closing the bypass channel. 5

A suitably trained exhaust outlet not shown is arranged on the opposite in the flow direction of the exhaust gas side of the heat transfer unit, but without flaps, and it would also be possible to arrange the flaps 15, 16 at corresponding positions on the outlet nozzle.

In the following, a possibility for controlling such a heat transfer unit in the warm-up phase of an internal combustion engine will be described by way of example.

When cold starting the internal combustion engine, it is desirable to increase the temperature of the lubricating oil as quickly as possible to reduce friction and emissions. This is in addition to the greater comfort of the passenger in the winter in a coupling to the heating of the passenger compartment.

During cold start, the exhaust duct 2 can be bypassed by closing the control device 15, so that in this phase, the flap 16 is in the open position and hot exhaust can flow through the bypass channel 5 uncooled. Through this exhaust stream and the connection of the bypass channel 5 to the oil passage 3 via the At this time, the control valve 11 is preferably closed, so that no coolant flows through the heat transfer unit and thus takes place only a heating of the oil whose volume flow in this phase by means of the Regulating device 13 can be regulated.

After this warm-up phase, the flap 16 can be closed and the flap 15 can be opened, so that now the exhaust gas flow is reduced to reduce the nitrogen oxides formed during combustion via the exhaust duct 2 and no more exhaust gas passes into the bypass channel 5. At the same time, the control valve 11 is opened, so that the exhaust gas channel 2 is now flowing around coolant and the oil passage 3 receives a heat-conducting contact via the partition wall 7 to the coolant channel 4. It is clear that the oil passage 3 in such an arrangement depending on the circuit of the control devices 15, 16 can take over both the function of an oil cooler and a Ölerwärmers.

In the further course after completion of the warm-up phase, depending on the engine characteristics and the applied engine load, a further control by means of the control devices 11, 15, 16 carried out in order to obtain a further reduction of pollutants.

The stated simple forms illustrate that it is possible to produce such a cooler in the die-casting of several parts and to connect them via a friction stir welding.

It is clear that by such a design of a heat transfer unit with combined exhaust and oil cooler and bypass for oil heating of the pollutant emissions of a vehicle can be significantly reduced, not least by the fact that the warm-up phase is significantly reduced. A heater can be completely eliminated, so that the number of used components is significantly reduced.

It should be clear that, depending on the desired temperature management and media used, a different arrangement of the channels to each other is conceivable, in particular by a space advantage is achieved that on a channel, in the present embodiment, the channel 3, both a heating and a cooling can take place.

Of course, the invention is not limited to the illustrated embodiment. Thus, a heat transfer unit can be created in which only the oil-traversable channel is cooled by both coolant and heated by the exhaust gas. Also, changes in the designs of the flow-through channels, for example in the form of plate or tube bundles are of course also conceivable as a different positioning of the input and output nozzle.

Claims (15)

Heat transfer unit for internal combustion engines - With a housing (1), in which at least a first channel (2) through which a first fluid to be cooled is arranged, - At least one of a second fluid permeable channel (3) is arranged, - And at least one of a coolant flow-through channel (4) is arranged, characterized in that
in the housing (1), a bypass channel (5) is formed for the first fluid to be cooled, via which the at least one first channel (2) through which the first fluid to be cooled can pass is bypassable. Heat transfer unit for internal combustion engines according to claim 1, characterized in that the at least one of the second fluid can be flowed through channel (3) between the bypass channel (5) and the coolant flow-through channel (4) is arranged. Heat transfer unit for internal combustion engines according to claim 1 or 2, characterized in that the fluid mass flow of the first fluid to be cooled in the bypass channel (5) and the first to be cooled by the first fluid to be cooled channel (2) via at least one control device (15, 16) controllable is. Heat transfer unit for internal combustion engines according to claim 3, characterized in that the fluid mass flow of the first fluid to be cooled in the bypass channel (5) and the first to be cooled by the first fluid to be cooled channel (2) via two valves (15, 16) is controllable, of which the first valve (15) in the region of an exhaust gas inlet nozzle (14) is arranged in the housing (1) in front of the first to be cooled fluid to be cooled channel (2) and the second valve (16) in the region of the Abgaseintrittsstutzens (14) in the housing (1) in front of the bypass channel (5) is arranged. Heat transfer unit for internal combustion engines according to one of the preceding claims, characterized in that the channel (4) through which the coolant can flow has a first common dividing wall (6) with the channel (2) through which the first fluid to be cooled flows, and a second common dividing wall (7). having the flow through the second fluid channel (3). Heat transfer unit for internal combustion engines according to one of the preceding claims, characterized in that the bypass channel (5) has a common partition wall (8) with the channel through which the second fluid can flow (4). Heat transfer unit for internal combustion engines according to one of the preceding claims, characterized in that the channel (4) through which the coolant can flow completely surrounds the channel (2) through which the first fluid to be cooled can cross-section. Heat transfer unit for internal combustion engines according to one of the preceding claims, characterized in that protrude into at least one of the channels (2, 3, 4, 5) of at least one of the partitions (6, 7, 8) ribs (9). Heat transfer unit for internal combustion engines according to one of the preceding claims, characterized in that the coolant flow via a control device (11) is controllable. Heat transfer unit for internal combustion engines according to one of the preceding claims, characterized in that the fluid mass flow of the second fluid via a control device (13) is controllable. Heat transfer unit for internal combustion engines according to any one of the preceding claims, characterized in that the first fluid to be cooled is exhaust gas and the second fluid is oil. Heat transfer unit for internal combustion engines according to any one of the preceding claims, characterized in that the heat transfer unit is constructed of die castings which are interconnected by friction stir welding. Heat transfer unit for internal combustion engines according to one of the preceding claims, characterized in that the heat transfer unit is at least partially integrated in the cylinder head. Heat transfer unit for the oil circuit of an internal combustion engine
with an oil-permeable channel (3)
and at least one channel (4) through which a coolant can flow, wherein the oil-permeable channel (3) is in heat-conducting contact with the channel (4) through which the coolant can flow,
characterized in that
in the heat transfer unit, an exhaust gas flow-through channel (5) is formed, which is in heat-conducting contact to the oil-permeable channel (3). Heat transfer unit for the oil circuit of an internal combustion engine according to claim 13, characterized in that the exhaust gas throughflowable channel (5) is the bypass channel of an exhaust heat transfer unit (2, 4).

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