DE3200683A1 - Supercharged internal combustion engine - Google Patents

Abstract

A heat exchanger (3) for cooling or preheating the combustion air of a supercharged internal combustion engine (1) has a self-contained system, in which a working medium is enclosed which participates in heat exchange with the combustion air, the working medium having a high thermal activity or functioning as latent heat store in the working temperature range. <IMAGE>

Description

5000 Cologne 80, December 15th 1981 Our reference: D 81/62

AE-ZPB P / Bn / B

Supercharged internal combustion engine

The invention relates to a device of the type specified in the preamble of the first claim,

It is known to use charge air coolers (heat exchangers) in which the cooling water of the internal combustion engine for cooling the charge air in the upper load area and for heating the charge air in the lower Load area is used (DE-OS 27 04 778).

Next to it are intercoolers, in which the ambient air is used to cool the charge air, known (DE-OS 17 51 209). With such intercoolers it is also known to take special measures to heat the charge air in the partial load area to meet, for example, to heat the charge air by exhaust gases from the internal combustion engine. That too Lubricating and gear oil are suitable means of preheating the charge air in the partial load area.

The known charge air coolers are primarily used to provide the prerequisite for a higher power density to create the internal combustion engine. This possibility is achieved in that the cooler Charge air causes a larger cylinder charge. In addition, there is also a charge air cooling system a beneficial effect on fuel consumption and exhaust quality, especially on the

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Smoke development, and goes hand in hand with a reduction in the thermal and mechanical load of the Internal combustion engine and all components delimiting the combustion chamber. This concerns for example in the case of rapid load changes, in particular the reduction of thermal alternating voltages. Furthermore, through the preheating of the charge air, the white smoke tendency of the internal combustion engine can be favorably influenced.

In order to cool the charge air, heat is extracted from the charge air in the heat exchanger. Through this the coolant heats up, and care must be taken to ensure that this heat is appropriate Way is discharged back to the environment. In this way it is possible to use the charge air cooling to be maintained indefinitely.

The same applies to the preheating of the charge air for longer idle and part load periods constant heat is to be provided (cooling water, engine oil or gear oil), which may then otherwise not available (e.g. for heating a driver's cab).

To do this, of course, a considerable effort has to be made, which consists in particular of that an additional heat exchanger or the usual heat exchanger is to be provided for liquid cooling is to be increased, or that in the case of recooling by means of ambient air, cooling air is more suitable for this Way is to promote. In addition, there are special requirements for the arrangement of such charge air coolers are to be asked, which are not always easy to meet, since the construction volume of such

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Heat exchanger can be significant. In addition, long air lines have an unfavorable effect on the operating behavior the internal combustion engine.

In many applications, the charge air is cooled only needed for a very short time. This applies to most passenger cars and light vehicles, for example Internal combustion engines for trucks in urban traffic. But this also applies to internal combustion engines Excavator use, in lifting rods and in other devices. So in such cases there is a maintenance the charge air cooling is not necessary for a long time, so that the measures on a Short-term effects could remain limited. The same applies to preheating in idle mode, provided this is also limited to short-term periods. In such cases, the cost of the intercooler can be increased can be significantly reduced.

The object of the present invention is for supercharged internal combustion engines with relatively fast Load changes to propose a simple system with which an almost evenly tempered combustion air is delivered.

This object is achieved according to the invention by the characterizing Features of the first claim solved. The invention is based on the basic idea that To use storage heat of a suitable working medium for the heat exchange, this heat is supplied by the charge air itself. This means that the heat exchanger next to the passages for the charge air still contains passages for a working medium which, depending on its temperature state, of the

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Combustion air extracts heat or adds heat to it, whereby the working medium itself is not in any external heat exchange with the environment. It deals So it is a self-contained system, whereby connections to the cooling water circuit or to there is no need for a connection with the cooling air of the internal combustion engine. The heat exchanger can therefore be switched on the internal combustion engine can be arranged much more freely, since its arrangement is only according to the requirements of the combustion air system got to.

The equalization of the combustion air, d. H. Lowering the combustion air temperature at high Load and increase in the combustion air temperature at low load caused due to the improved Fuel / air ratio during all acceleration processes higher performance, lower fuel consumption, improved Exhaust quality and has a relief of mechanical and thermal stresses, such as those in particular occur with rapid load changes, and thus also an extension of the service life of the Engine result. The effect is independent of the type of cooling of the internal combustion engine and their regulation and is retained even with charge-air-cooled internal combustion engines, since the combustion air still subject to considerable temperature fluctuations upon exit from the heat exchanger can be.

During operation, the working medium will adjust to a temperature whose mean value will be from the load spectrum of the internal combustion engine and

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thus as the mean value of the temperatures of the enforced Combustion air results. In relation to the rapid temperature change in the combustion air that of the working medium will change much more slowly because of its greater heat content. at The working medium therefore has a quasi-stationary effect in a similar way to spontaneous load changes The heat exchanger continuously flows through the cooling water. The Adjust the temperature of the working medium to the temperature of the combustion air, so that there is then an exchange of heat can no longer take place.

The change in temperature of the combustion air over time is determined by the size of the heat exchanger and the amount and type of working medium can be influenced.

In internal combustion engines, when they are used, due to the way they operate, only a short-term overload is possible, an overload can easily be allowed. This applies, for example, to the short-term overload capacity of units, especially the immediate standby units. Also at Acceleration processes for cars and trucks - when overtaking and on short inclines the operation of the arrangement according to the invention that of a conventional charge air cooler, so that the injection quantity can be increased significantly during the acceleration process.

In internal combustion engines, the short acceleration processes are exposed with longer part-load periods in between, the effectiveness is the arrangement according to the invention is identical to

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those of the previously known heat exchangers, with the difference that they are in terms of their effort however, they are much simpler and cheaper. In addition, the heat exchanger designed according to the invention can even afterwards - usually even without major changes to the internal combustion engine - be installed.

Even with prolonged full load or idling, there can be no negative influence on the operation of the Internal combustion engine take place when they have no higher continuous output than an internal combustion engine without Has cooling the combustion air. The arrangement according to the invention is therefore less Effort an equalization of the combustion air temperature achieved in all transition states.

The heat-exchanging medium can easily be water, optionally with an anti-freeze agent mixed, can be used.

If the heat exchanger is hermetically sealed on the water side, the entire arrangement is complete practically maintenance-free and wear-free. In this case, however, a gas cushion should be on the water side to absorb the pressure fluctuations that occur with heating and cooling.

In a further embodiment of the invention, it is proposed that a working medium be used instead of water to use higher heat storage capacity. This is the case, for example, if the selected

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Medium in the working temperature range works as a latent storage that a phase change or a exhibits heat turnover associated with a chemical reaction. Such a means is for example Stearin, the phase change of which is around 52 ° C. Above this temperature it melts and below it solidifies, the heat of fusion or the heat of liquefaction being around 130 Ws / cm (31 kcal / 1). This means is therefore particularly suitable as a working medium for the intended Temperature leveling. For this, however, it is necessary that the heat exchange between the stearin on the one hand, and the charge air carried past the side walls on the other can take place. So it must be taken care that both on the combustion air side as well as on the working medium side under all conditions there are high heat transfer coefficients. the in air-cooled internal combustion engines common oil / air heat exchangers with oil separators, the surface of which are significantly enlarged by metal cooling fins connected to the partition walls and the In addition, they are suitable for absorbing compressive stresses in the vagina, are particularly designed for this suitable, whereby stearin is now preferably filled in instead of oil.

Filling with glycerine is also advantageous, as there is a high temperature in the relevant temperature range Possesses latent heat.

Instead of stearin or glycerin, according to another development of the invention, it is possible to use salt hydrate - for example potassium fluoride tetrahydrate (KF.4H ₂ O) - as the working medium

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Heat of fusion at 18.5 ° C is 336 Ws / cm ³ - to be used. With this value it corresponds almost exactly to the heat of fusion of the water, which is available at an even lower value, namely at 0 ° C. This hydrate is therefore particularly suitable for use with low outside temperatures and for operation with longer partial load periods, so that the working medium can also cool down to below the conversion temperature. The very slight change in volume during the phase change is also advantageous here. _{Na 2} SO also brings favorable conditions. . 10 H ₂ O (Glauber's salt) [phase change at + 32.4 ° C, heat of fusion 354 Ws / cm] and sodium hydrogen phosphate (Na ₀ HPO. 12 H ₀ O) [phase change at 35.2 C, heat of fusion 403 Ws / cm] with .

The shape of the heat exchanger can closely follow the usual shape of a cross-flow or cross-counter-flow lean against the pressurized heat exchanger. As before, the combustion air is between the sheaths of the working medium, which are connected by narrow lamellae.

If the sheaths are dimensioned appropriately for the working medium, one can also use Take oil - especially heavy oil - into consideration, as it only causes slight changes in pressure during operation are expected so that the scabbards can be made relatively simple and easy.

In addition to the already mentioned sheath design, which is preferably used in box shape, can the same structure also in a cylindrical

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Place container shape. It is also possible to use circular or spiral-shaped finned tubes - ribbed longitudinally or transversely on the air side depending on the installation situation - which are preferably filled with the working medium on the inside. The tubes can be ribbed on the outside and inside. A ribbing on the side of the working medium is necessary if the heat transfer on the wall requires this (e.g. in the case of oil, stearin or hydrates).

In the context of the invention, it is also possible to use adsorption storage in which the heat of evaporation of the substance involved is stored.

In a simple manner, such an inventive Heat exchangers also made from heavy metal plates - preferably made from tinned iron plates or from Copper plates - are made, between which air fins are arranged over which the combustion air is routed. Because of the large specific mass the storage heat of the heavy metal is only slightly below that of the water. A heat exchanger made of copper has the advantage that it is equally effective over the entire depth, because of the high Thermal conductivity of the copper also means that a considerable amount of heat is transported within the plates.

To increase the storage capacity of the heat exchanger, the storage volume can be simplified Way to be expanded. For this purpose, it is proposed in an embodiment of the invention that the closed System of the heat exchanger to at least one

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arranged inside or outside of the heat exchanger and filled with the working medium additional container is connectable. This additional container can be used in any space-saving manner on the Internal combustion engine be provided, since it is independent of other units by conventional connecting lines can be connected to the heat exchanger. By the enclosed in the additional container The working medium becomes the area of application of the heat exchanger with the same heat exchange surface extended to longer lasting full load and part load periods. The circulation of the working medium represents the due to the different temperatures in the heat exchanger and in the additional tank conditional thermosyphon effect safe enough.

However, it is also possible, as proposed in a further development of the invention, to add a circulation pump use, whereby the circulating volume of the working medium in the heat exchanger and in the additional tank depends on the temperature can be regulated. A simple circulating pump can be used for this, its speed z. B is regulated as a function of the charge air temperature. Another possibility is to Provide thermostatic valves that depend on an adjustable upper and lower maximum temperature value Release and close or more or less throttle the connection lines to the additional tank.

It is also possible, especially when water or oil is used as the working medium of the heat exchanger it is provided to arrange elements in the additional container that are filled with a working medium that

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has a phase change or a chemical reaction in the relevant temperature range, so as to high storage heat of these media if required to expand the cooling or preheating capacity of the To be able to use the heat exchanger.

Another embodiment of the invention provides for the additional container with cooling liquid or lubricating oil to act on the internal combustion engine to im Part-load and braking operation can also use these media to preheat the charge air.

In a further embodiment of the invention it is proposed that the working medium be in the sheaths to provide a possibility for heating the medium - mainly when the engine is at a standstill - see above that the combustion air can be preheated as a starting aid. In particular, it offers an electric heater for this purpose.

The invention is explained in more detail below using selected examples shown schematically They represent:

Fig «1 shows a side view of a charged one Internal combustion engine with the heat exchanger according to the invention;

Fig. 2a shows a possible interior view in

Section of the heat exchanger; Fig. 2 b and c show a circular cylindrical built-on heat exchanger;

3 a - c show a finned tube heat exchanger;

FIGS. 4 a - d show alternatively constructed finned tube heat exchangers;

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Fig. 5 a - c show finned tube heat exchangers with

circular or spiral tubes;

FIGS. 6a-c show a heat exchanger according to the invention with an additional container in FIG three different views;

Fig. 7 shows a side view of a supercharged internal combustion engine with the heat exchanger according to the invention and an additional container; Fig. 8a + b show an additional container that the lubricating oil circuit of the internal combustion engine can be connected, in two different views;

9a + b show graphs for temperature / time behavior of the structure constructed according to the invention

Heat exchanger with different working media.

In Fig. 1 is a side view of a supercharged internal combustion engine is shown. With 1 is the

Internal combustion engine itself, with 2 the compressor of an exhaust gas turbocharger, with 3 the heat exchanger, with 4 the air duct between the compressor 2 and the heat exchanger 3 and with 5 the air duct from the heat exchanger 3 to the cylinder head or the cylinder heads. The heat exchanger 3 can have any suitable shape, that is to say cylindrical, oval or box-shaped.
30th

The invention is described in Fig. 1 on an air-cooled internal combustion engine with individual cylinder heads, however, it is not limited to this.

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Some possible designs of the heat exchanger 3 operating according to the invention are shown in FIGS. 2-5 shown.

The function of the heat exchanger 3 according to FIG. 1 is shown in FIG. In the management channels 6 for the combustion air, air lamellae 6.1 are provided, which are parallel to the direction of flow the combustion air.

Sheaths 7 for the working medium are arranged between the guide channels 6 in a manner known per se. In the sheaths 7 lamellae can be used to increase the heat transfer and compressive strength be arranged.

The heat exchanger 3 according to FIGS. 2-5 can be filled with water, stearin or hydrate as the working medium exhibit.

While the heat exchanger 3 in Fig. 2a is constructed as a box-shaped plate heat exchanger the heat exchanger 3 in Fig. 2b constructed as a circular cylindrical sheath heat exchanger. This form has the advantage that it can be installed more easily in the air duct 4. The heat exchanger in Fig. 2c differs from this in that the plates 7 ', which are solidly formed from Schmermetall, instead of the Divorce 7.

3-5 show instead of plate heat exchangers only heat exchangers made of finned tubes.

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In Fig. 3a, a heat exchanger 3 is shown in the form of a hexagon with rounded corners. In him are individual.rippenrohre 8 inserted axially parallel to each other. Each finned tube 8 has external ribbing from either simple, optionally slotted air lamellae 8.1 or from double lamellae with an offset arrangement (Fig. 3b, c). The combustion air is in the heat exchanger 3 between the air fins of the individual finned tubes 8 and the spaces between the individual finned tubes 8 led. Each finned tube can be closed at both ends and with the working medium be filled or all finned tubes 8 are on the working medium side with each other on both sides Expansion tank connected. The combustion air is parallel to the pipe's longitudinal axes guided.

In Fig. 4a a built up from individual tubes 9 is Heat exchanger 3 shown, in which the combustion air flows through axially parallel. In these Tubes 9 can be the finned tubes 9.1 shown in FIGS. 4b-d, which are filled with working media are inserted and fastened. The finned tubes 9.1 are outside (Fig. 4d) or inside (Fig. 4b, c) cross-ribbed, depending on requirements. Here, too, the air lamellae 9.2 can be used as Be constructed with a single or double lamella. The arrangement of the individual slats shows for example FIG. 4b, which shows a partially broken longitudinal section of a finned tube 9.1 represents.

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A finned tube heat exchanger is also shown in FIGS. 5a-c, in which, however, the finned tubes 10 circular or spiral-shaped around the longitudinal axis of the heat exchanger, parallel to which also the combustion air flows, are arranged. Depending on requirements, it can also be in the longitudinal axis of the heat exchanger a finned tube 11 can be arranged concentrically. The finned tubes 10 also have transverse ribs here 10.1 for guiding the combustion air. Only the finned tube 11 that may be present has external longitudinal ribs 11.1 for guiding the combustion air.

Fig. 6a shows a side view of the invention Heat exchanger 3 with additional container 12. The combustion air flows through in the direction of arrow 13 the heat exchanger 3. The working medium is circulated by the different Thermosiphon effect caused by temperatures. 20th

The heat exchanger according to FIG. 6a is shown in FIG. 6b in a sectional front view and in FIG. 6c in the Cross-section shown.

7 shows a side view of an internal combustion engine 1 with the heat exchanger 3 according to the invention and an additional tank 12 which is arranged separately from the heat exchanger 3. Here the Circulation of the working medium through a circulation pump 15, which is designed to be controllable as a function of temperature can be ensured.

In Fig. 8a, an additional container 12 is shown, which via lines 16 with the lubricating oil circuit the internal combustion engine is connected.

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Pig. 8b shows the additional container 12 according to FIG. 8a in a sectional view. In it are lamellar executed sheaths 14.1 for the working medium and Plussigkeitsscheiden 16.1 provided for the working medium to be able to preheat the additional container if necessary.

In Fig. 9a, b a temperature-time diagram is shown, on which the function of the heat exchanger according to the invention is explained.

The temperature profiles in Fig. 9a are at a Supercharged internal combustion engine with a displacement of around 6 liters, a water content in the heat exchanger of 2 liters and a pressure ratio of the combustion air of 1 to 1.8 during an acceleration process achieved in the medium speed range. The temperature profile according to curve 17 is without, that according to curve 18 with the one according to the invention Heat exchanger reached. The temperature profile according to curve 19 represents that of the water in the heat exchanger.

As curve 19 shows, with the parameters described above, the water is in about 30 seconds. warmed up by around 25 °. This heat of the combustion air is withdrawn from the initially cool at a compressor inlet temperature of about 20 ⁰ C and a compressor outlet temperature of 100 C to about 35 ° C to 40 ⁰ C and at the end of the acceleration process (after 30 seconds) even by 20 ° C is than without a heat exchanger (comparison of curves 17 and 18). As a result, the internal combustion engine receives about 10% more combustion air due to the heat exchanger according to the invention.

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During the subsequent relief process (from 30 seconds to 60 seconds) the combustion air remains around 15 C warmer than without cooling. During the entire process, the temperature fluctuation of the combustion air is approx. 80 ^° C. without and only approx. 50 ^° C. with the heat exchanger according to the invention.

In Fig. 9b the same process is shown in a heat exchanger with stearin filling (curve 19 '). A phase change in the temperature range of 52 ° C corresponds approximately to the same heat capacity like that of water with a temperature rise of 30 ° C, so in this case the full The cooling effect would last over the entire acceleration period because of a rise in temperature of the stearin not yet done during this time.

As a comparison of the curves 17 and 18 in FIG. 9b shows, at the beginning of the acceleration process a temperature difference of approx.

35 ° C and scored a temperature difference of about 30 ⁰ C by the heat exchanger according to the invention at the end (after 30 sec). At the end of the relief process (after 60 seconds) the combustion air remains around 20 ^° C. warmer. During the entire process, the temperature fluctuation of the combustion air is only approx. 30 C.

The diagrams make it clear that the working medium of the heat exchanger according to the invention the absorbed heat is only stored in order to later return it to the cooled combustion air

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to give off, so only an exchange of heat with the combustion air exists, a substantial equalization of the combustion air with simple means is achieved.

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Claims (17)

5000 Cologne 80, December 15th, 1981 Our reference: D 81/62 AE-ZPB P / Bn / B Claims [1. / Supercharged internal combustion engine with a heat exchanger for cooling and / or preheating the Combustion air, characterized in that the heat exchanger (3) has a self-contained system in which a working medium which is in heat exchange with the combustion air without heat exchange to the outside of the heat exchanger (3) is included. 2. Supercharged internal combustion engine according to claim 1, characterized in that the working medium has a high heat storage capacity. 3. Supercharged internal combustion engine according to claim 1 or 2, characterized in that as Working medium water - if necessary mixed with antifreeze - is provided. 4. Supercharged internal combustion engine according to one of the preceding claims, characterized in that that the working medium works as a latent storage in the working temperature range by a Has a phase change or a heat conversion associated with a chemical reaction. - 2 - 15.12.81 D 81/62 5. Supercharged internal combustion engine according to one of the preceding claims, characterized in that that the walls of the heat exchanger (3) separating the combustion air from the working medium are ribbed and made of a material with high thermal conductivity exist. 6. Supercharged internal combustion engine according to one of the preceding claims, characterized in that the working medium consists of a salt hydrate - for example KF.4H ₂ O (potassium fluoride _{tetrahydrate) or Na 3} SO ₄ .10H ₂ O or Na ₃ HPO ₄ .12 H ₂ O - . 7. Supercharged internal combustion engine according to one of the preceding claims, characterized in that that the heat exchanger (3) in the air supply (4, 5,) between the compressor (2) and the internal combustion engine (1) is arranged and designed as a sheath cooler. 8. Supercharged internal combustion engine according to one of the preceding claims, characterized in that that the heat exchanger (3) is formed from finned tubes (8, 9.1) which are ribbed on the inside and / or outside are, with the working medium inside or outside - preferably inside the finned tubes (8, 9.1) - is located. 9. Supercharged internal combustion engine according to one of the preceding claims, characterized in that that the storage spaces receiving the working medium are connected to one another and that they 200683 - 3 - 15.12.81 D 81/62 a sufficient compensation volume to reduce the pressures generated during heating exhibit. 10. Supercharged internal combustion engine after a of the preceding claims, characterized in that the working medium acts as an adsorption store in that it stores the heat of vaporization of a suitable substance.
10 11. Supercharged internal combustion engine according to one of the preceding claims, characterized in that that as storage material heavy metal plates (7 ') - preferably copper plates or tinned iron plates - are provided. 12. Supercharged internal combustion engine according to one of the preceding claims, characterized in that that the closed system of the heat exchanger (3) with at least one inside or outside of the heat exchanger (3) and with the working medium filled additional container (12) is connectable. 13. Supercharged internal combustion engine according to one of the preceding claims, characterized in that that the working medium in the heat exchanger (3) and in the additional container (12) can be circulated. 14. Supercharged internal combustion engine according to one of the preceding claims, characterized in that that the circulation of the working medium in the heat exchanger (3) and in the additional container (12) is temperature-dependent regulated takes place. Z UU b ö J - 4 - 15.12.81 D 81/62 15. Supercharged internal combustion engine according to one of the preceding claims, characterized in that since elements are provided in the additional container (12) which are filled with a working medium, wherein the working medium undergoes a phase change or a chemical reaction in the relevant temperature range having. 16. Supercharged internal combustion engine according to one of the preceding claims, characterized in that that the additional container (12) from the cooling liquid or the lubricating oil of the internal combustion engine (1) can be acted upon. 17. Supercharged internal combustion engine according to one of the preceding claims, characterized in that that electrically operating heating rods are provided in the working medium of the heat exchanger (3) are that with an electrical energy source depending on the temperature of the combustion air or the ambient temperature are connectable.