EP0496942A1 - Vapour-cooled internal combustion engine - Google Patents

Abstract

Vapour-cooled internal combustion engine (21), in which a cooling system (3) through which a liquid coolant can flow and which can be pressurised is connected to a compensation reservoir (1) and a radiator. The compensation reservoir (1) is connected by means of a connecting line (2) to a zone of the cooling system (3) which is constantly filled with liquid coolant during operation of the internal combustion engine (21). The compensation reservoir (1) is assigned at least one relatively movable, liquid-tight partition wall (4), which subdivides the compensation reservoir (1) into a space (5) containing liquid coolant and a spring space (6). <IMAGE>

Description

The invention relates to an evaporation-cooled internal combustion engine in which a cooling system through which a liquid coolant can flow and which can be pressurized can be connected to an expansion tank and a cooler.

Such an internal combustion engine is known from US 4,648,356. According to this, the cooling system essentially consists of a water jacket of the internal combustion engine, a cooler which is designed as a condensation cooler, a condensate tank and a container which is divided into two partial chambers by a partition wall, the chamber facing away from the cooling system being open to the atmosphere. The task of this system is to temporarily draw the air in the hermetically sealed system out of the system and to keep it away from the condenser in order to improve the function of the system. The air, which is detrimental to the function of the system, is stored in the container with the partition when the internal combustion engine is at operating temperature and is conveyed back into the system when the machine is cooling in order to avoid the creation of a vacuum. It should be noted, however, that large parts of the cooling system are moistened when the machine cools down. At low outside temperatures, the moisture in the system can freeze and lead to malfunctions or the destruction of the cooling system. In addition, the performance characteristics due to the sensitive sensors that are necessary to determine the liquid levels and due to the insufficient influence on the Satisfy the cooling characteristic. A further disadvantage is that the amount of condensate cannot be regulated in conjunction with the condensate temperature, which can lead to stress cracks in the internal combustion engine when there are large temperature differences between the condensate and the component temperature. In addition, the filling of the cooling system is comparatively complex because the liquid coolant has to be measured precisely.

The invention has for its object to further develop an evaporative-cooled internal combustion engine of the type mentioned in such a way that there is no impairment of the performance properties at low outside temperatures, that the efficiency and performance characteristics of the cooling system of the internal combustion engine are significantly improved and the reliability is increased.

This object is achieved according to the invention in an internal combustion engine of the type mentioned at the outset with the characterizing features of claim 1. The subclaims refer to an advantageous embodiment.

In the evaporative-cooled internal combustion engine according to the invention, it is provided that the expansion tank is connected by means of a connecting line to a zone of the cooling system which is always filled with liquid coolant during operation of the internal combustion engine, and that the expansion tank is at least one relatively movable, Liquid-tight partition is assigned, which divides the expansion tank into a liquid coolant-containing space and a spring space. The volume of liquid stored in the expansion tank has the function of a water reservoir in addition to pressure equalization in the system. Even in extreme driving situations, such as when cornering very quickly, and when there is a large amount of steam in the condenser, there is no danger that the coolant pump will suck in steam instead of liquid coolant. This results in an extremely high operational reliability of the cooling system.

In evaporative cooling, the boiling point of the coolant is adjusted according to the pressure in the cooling system. The characteristic curve of the system pressure can be influenced by the relatively movable, liquid-tight partition, which is arranged in the expansion tank. The spring chamber of the expansion tank can be hermetically sealed, the relatively movable partition wall being supported on the enclosed air (air spring). A support on a spring element arranged in the spring chamber with spring chamber open to the atmosphere is also conceivable. With increasing pressure in the cooling system and increasing volume of the coolant-containing space, the pressure on the spring element also increases.

The cooling system contains at least one condensation cooler. This cooling system is particularly economical and functions well and is particularly suitable for large series.

According to an advantageous embodiment, it is provided that a convection cooler is assigned in parallel to the condensation cooler. It is advantageous here that a temperature of the coolant is present in the area of the coolant pump, which temperature is composed of the condensate temperature and the temperature of the coolant cooled by the convection cooling. This temperature is always below the boiling point of the coolant, so that no cavitation occurs even through the suction pressure of the coolant pump. The service life of the coolant pump is increased by the fact that it delivers steam-free. It is also advantageous that the liquid coolant is conveyed into the internal combustion engine at a largely constant inlet temperature.

The condensation cooler has vertical coolant passage lines. This configuration results in a high efficiency of the condenser in that the condensate arising runs off particularly quickly from the coolant passage lines in the direction of the coolant discharge line. It is also advantageous that the coolant inlet into the coolant passage lines of the condensation cooler is above the level of the liquid coolant when the machine is warm. This configuration ensures that only evaporated, gaseous coolant and no larger liquid components pass through the coolant passage lines, which further increases the efficiency of the cooling system.

In order to ensure that when the internal combustion engine is at operating temperature, only evaporated coolant passes through the coolant passage lines of the condenser, a condensate return can be assigned to the condensation cooler. The condensate return feeds the condensate accumulating in the area of the inlet of the coolant passage lines without it running through the condensation cooler in the direction of the coolant pump. The condensate return also contributes to the high efficiency of the cooling system.

The cooling system is provided with a coolant inlet line and a coolant outlet line and is advantageously completely filled with liquid coolant in the case of steam-free operation. The cooling system is characterized by very good usage properties, easy filling and high reliability. When the machine is cold, the cooling system can be filled to the brim through a filler neck, so that there is no need to measure the liquid coolant exactly. Vent lines are provided both on the cooling system and on the internal combustion engine, which end in the cover of the filler neck. The cover of the filler neck contains a pressure relief valve that opens to the atmosphere at critical system pressure to blow off steam. Because the coolers are completely filled with coolant during the steam-free operation, there is no risk of the coolers being damaged by freezing, even in winter, when the outside temperature is low. The coolant, which mostly consists of water and contains antifreeze, is contained in the entire cooling system and, compared to the prior art, has no zones without antifreeze. There is also the possibility that the in the steam entering the condenser entrains liquid constituents which are collected in the area of the coolant passage lines of the condenser and are fed to the coolant pump by the condensate return through the condensate return.

According to a particularly uncomplicated, economically inexpensive embodiment, it is provided that a first check valve can be arranged between the coolant inlet line and the coolant outlet line, which opens only in the direction of the coolant outlet line. The first check valve has the task of releasing the direct passage between the coolant supply line and the coolant discharge line in the case of a steam-free internal combustion engine, that is to say during the starts and shortly thereafter, so that the circulating coolant can be quickly heated without cooling. The rapid heating during the warm-up phase minimizes wear on the adjacent internal combustion engine and reduces pollutant emissions.

According to a further advantageous embodiment, an expansion thermostat can be connected upstream of the coolant drain line, wherein the expansion thermostat can be assigned to the convection cooler and a bypass adjacent to the convection cooler and regulates the coolant mass flow from the convection cooler and bypass in the direction of the coolant drain line. Instead of the expansion thermostat, an externally controllable thermostat can also be used. The use of a thermostat is particularly advantageous for influencing the component temperatures of the internal combustion engine. When the internal combustion engine is cold, the expansion thermostat closes the coolant passage through the convection cooler and releases the coolant passage through the bypass. The coolant takes the comparatively direct one Path between coolant supply line and coolant discharge line via the bypass without it flowing over the radiator. The coolant is fed to the internal combustion engine largely uncooled. This shortens the warm-up phase of the internal combustion engine and reduces wear and pollutant emissions. As the temperature of the coolant rises, the expansion thermostat gradually closes the coolant passage through the bypass and clears the way through the cooler. The cooled coolant is then fed back to the internal combustion engine for cooling. The advantage here is that the cooling system has a more constant operating behavior. Interference, for example by switching the vehicle interior heating on and off or by an oil cooler, can thereby be reduced. It is also advantageous that the greater flow of coolant through these components requires a greater heating or cooling capacity.

In the coolant drain line of the cooler, a coolant pump can be arranged, which is assigned a second check valve that opens in the direction of the internal combustion engine. The advantage here is that the internal combustion engine can be arranged at any height, relative to the cooler, without the coolant from the internal combustion engine can flow back into the cooler. This ensures an adequate coolant level in the internal combustion engine at all times. If, for example, the internal combustion engine is switched off after a long full load run and the condensation cooler is almost completely filled with steam, there is no risk that when the motor is also switched off Coolant pump the coolant located in the internal combustion engine flows back into the cooler and thus leads to overheating and irreparable damage to the internal combustion engine.

A first valve can be connected upstream of the coolant pump. The valve is expediently to be arranged such that it is provided between the coolant return from the coolers and the line to the adjacent coolant pump. According to an advantageous embodiment, it is provided that the first valve is designed as a float valve and the supply line to the coolant pump can be closed if necessary without blocking the connecting line between the expansion tank and the coolant pump. If, for example, there is no longer any liquid coolant in the intake area of the coolant pump due to very fast cornering, the first valve closes the access from the cooler to the coolant pump. The coolant pump then temporarily transports liquid coolant from the coolant reservoir, which is formed by the expansion tank, and feeds it to the internal combustion engine. If the level of the liquid coolant in the cooler rises again, the first valve is moved into the open position, so that the coolant pump draws liquid coolant out of the coolers.

A second valve can be connected upstream of the condensation cooler. If there is a convection cooler parallel to the condensation cooler, the second valve is also upstream of this. The second valve can be designed as a float valve. The second valve has the task of only allowing the coolant to pass through the cooler when the coolant has warmed up and to a certain extent already evaporated. With the onset of evaporation, increasing pressure and thereby falling coolant level, the second valve opens the passage to the adjacent coolers, so that the internal combustion engine is cooled and protected against overheating.

The partition in the expansion tank can consist of a piston. The piston, which divides the expansion tank into a space containing liquid coolant and a spring space, is a particularly simple and economical component to manufacture. The partition can also be formed, for example, by a rolling membrane.

The partition can be supported on a compression spring arranged in the spring chamber. It is advantageous here that the spring is arranged in the coolant-free space and, as a result, spring bodies made of foam and elastomeric material can be used in addition to helical compression springs and disc springs. The coolant surrounding them does not affect their performance.

The spring chamber can be connected to the intake system of the internal combustion engine by means of a vacuum line, which can be closed by at least one shut-off valve. It is a prerequisite that a suction system is available and that it also provides a vacuum that is sufficient to operate the partition properly. If the internal combustion engine is a diesel engine, the vacuum line can advantageously be connected to the vacuum pump of the brake system.

In evaporative cooling, the boiling point of the coolant is adjusted according to the pressure in the cooling system. Depending on the level of the system pressures in the cooling system and the associated different boiling temperatures of the coolant, the temperature of the internal combustion engine can be optimally adapted to the respective load condition. To regulate the system pressure, provision is made to apply a negative pressure to the relatively movable, gas-tight partition. The application of negative pressure can be generated by the suction system of the internal combustion engine or a separately arranged suction pump. By deflecting the partition in the expansion tank, the total volume of the cooling system and thus the system pressure are regulated depending on the operating point of the internal combustion engine. The desired system pressure can be determined, for example, from the following parameters: coolant temperature, component temperature, amount of vacuum in the intake manifold, position of the throttle valves, speed of the internal combustion engine, injected fuel quantity, ambient temperature and vehicle speed. In the case of electronically controlled internal combustion engines, a large number of the auxiliary variables mentioned above are available anyway, so that no additional sensors are required.

A vacuum accumulator can be assigned to the vacuum line. This is particularly useful if the suction system of the internal combustion engine does not provide a vacuum that is sufficient in all load states Adapt system pressure in the cooling system to the respective load conditions. When idling, when a comparatively high system pressure is required, which results in a high boiling temperature and thus a rapid warm-up of the internal combustion engine, the suction system without a vacuum accumulator provides a high vacuum, while in the full load range when low system pressure and a low boiling temperature of the coolant are required, In order to avoid overheating of the internal combustion engine, the suction system generates only a little negative pressure, which under certain circumstances may not be sufficient to further reduce the system pressure in the cooling system. To avoid these disadvantages, it is provided that a vacuum accumulator is arranged in the vacuum line, which ensures a sufficient supply of the expansion chamber in the expansion tank with vacuum in each load range.

Exemplary embodiments of the evaporation-cooled internal combustion engine according to the invention are shown schematically in the accompanying drawings and are described in more detail below.

1, 2, 3, 4, 5 and 6 each show an evaporatively cooled internal combustion engine 21 in which a cooling system 3 through which a liquid coolant can flow and which can be pressurized is connected to an expansion tank 1 and a cooler. In these cases, the cooler consists of a condensation cooler 7 and a convection cooler 8 arranged parallel thereto. The expansion tank 1 is assigned a relatively movable, liquid-tight partition 4 in the form of a piston, which divides the expansion tank 1 into one liquid coolant containing space 5 and a spring space 6 divided. At least the condensation cooler 7 has vertical coolant passage lines 9.7, as explicitly shown in FIGS. 1 to 3. The coolant passage lines through the condensation cooler 7 also run vertically in FIGS. 4 to 6, but this is not shown in these figures in order to ensure better clarity. In addition to the vertical coolant passage line, a condensate return 10 is provided in all figures, which is arranged in the condensation cooler 7. The vertical coolant passage lines as well as the condensate return ensure good efficiency of the cooling system 3.
In Fig. 1, the expansion tank is closed to the environment. If the partition 4 moves with increasing pressure in the cooling system 3 in the direction of the spring chamber 6, the enclosed gas located therein acts like an air spring. 2, the partition 4 is supported on a compression spring 18 arranged in the spring chamber 6, the spring chamber 6 being connected to a suction system 22 via a vacuum line 19. In the vacuum line 19, a check valve 20 is provided, which can be closed if necessary.
In FIG. 3, the first check valve 13 from FIGS. 1 and 2 is replaced by an expansion thermostat 24 which regulates the coolant mass flow from the convection cooler 8 and the bypass 25 in the direction of the coolant drain line 12 as a function of the coolant temperature. The temperature of the coolant reaching the coolant pump 14 is composed of a maximum of three partial temperatures. It results from the temperature of the uncooled coolant from the bypass 25, the temperature of the coolant flowing through the convection cooler 8 and the Temperature of the condensate that exits the condensation cooler 7. By using expansion thermostats with different expansion coefficients, it is possible to operate the basically the same cooling system on internal combustion engines that have to be cooled to different degrees.

The evaporative-cooled internal combustion engines according to FIGS. 1 to 3 are characterized by compact dimensions, simple construction and particularly economical to manufacture. 4 to 6, an evaporative-cooled internal combustion engine is shown as a simplified block diagram for the sake of clarity. Of course, there is also the possibility of combining the components in a housing, similar to FIGS. 1 to 3. The detailed design of the condensation cooler 7 and the convection cooler 8 can be found in FIGS. 1 to 3.

Fig. 4 shows an evaporative-cooled internal combustion engine according to the invention, in the cold state before start-up or shortly after starting. The cooling system is completely filled with coolant and is steam-free. The liquid coolant-containing space 5 of the expansion tank 1 has its smallest volume.

5 shows the internal combustion engine according to FIG. 4, the amount of heat supplied being smaller than the amount of heat which can be removed.

Fig. 6 shows an extreme case for which the cooling system must be designed. The amount of heat supplied is equal to the amount of heat that can be removed. This is the case if, for example, the mountains are driven at low speeds for a long time under full load.

4 to 6 differ essentially from FIGS. 1 to 3 in that the direct connection between the expansion tank 1 and the condensation cooler 7 is closed with the coolant drain line 12 and the connecting line 2, in which a check valve is arranged, in the bypass 25 is performed. The main advantage of this embodiment according to FIGS. 4 to 6 is the fact that the condensate is not fed directly to the internal combustion engine. This avoids that comparatively cold condensate is fed directly, for example, into a very hot internal combustion engine (full load) and can lead to high thermal stresses, possibly even stress cracks.

The expansion thermostat, which, as shown here for example, is arranged at the coolant outlet of the convection cooler and bypass, but can also be arranged at its inlet, has the same functions as the expansion thermostat from FIG. 3.

The following must be carried out for the system to function:
1 shows the evaporative-cooled internal combustion engine 21 according to the invention with a steam-free cooling system 3, shortly after starting, when it has not yet reached its optimum operating temperature. Both the convection cooler 8 and the condensation cooler 7 are completely filled with liquid coolant, which can consist of water containing antifreeze. Even at very low outside temperatures, there is no risk that the cooler will be damaged by freezing. In addition, the filling of the cooling system 3 with cooling liquid is particularly simple. To fill in cooling liquid, the cover of the filler neck 23 is removed and coolant is filled in until the liquid is level with the filler neck 23.

The second valve 17, which is designed as a float valve, lies against its upper sealing seat in the direction of the condensation cooler 7 because it is completely surrounded by cooling liquid. In addition, the second valve 17 seals the access to the convection cooler 8. At the same time, the first check valve 13 is open due to the closed second valve 17 and the suction pressure of the coolant pump 14, as is the first valve 16, which, like the second valve 17, is designed as a float valve. This causes the coolant to be pumped through the internal combustion engine 21 in a small circuit. The coolant passes from the coolant supply line 11 past the first check valve 13 and the first valve 16 to the coolant pump 14 and is fed back from there past the second check valve 15 to the internal combustion engine 21. The first check valve 13 is only open as long as the second valve 17 is closed is. The expansion tank 1 has the lowest volume in the area of the coolant-containing space 5. The volume of the spring chamber 6 is greatest.

FIG. 2 shows the internal combustion engine 21 according to FIG. 1, the operating temperature of which has risen, with part of the liquid coolant having already evaporated and being largely in the condensation cooler 7. Due to the increased pressure in the cooling system 3, the partition 4 of the expansion tank 1 has been moved in the direction of the spring chamber 6 in order to release volume for the steam that is produced. As a result of the evaporated coolant components, the level of the liquid coolant in the convection cooler 8 and the condensation cooler 7 has decreased, as a result of which the second valve 17 has opened the passage in the direction of the condensation cooler 7. At the same time, the passage to the convection cooler 8 was opened, through which liquid coolant flows. The coolant passage lines 9.7 of the condensation cooler 7 have an inlet which is approximately at the level of the valve seat of the second valve 17 and is only surrounded as quickly as possible by vaporous coolant when the coolant begins to evaporate. This ensures that the coolant passage lines 9.7 of the condensation cooler 7 are only flowed through by steam, which requires an extremely high efficiency. The coolant located in the area of the inlet opening of the coolant passage lines 9.7 is discharged via a condensate return 10. The vertically arranged coolant passage lines 9.7., 9.8 of the condensation cooler 7 and the convection cooler 8 have the advantage of contributing to a good efficiency of the cooling system. The first check valve 13 closes when the second one is open Valve 17 the direct circulation path to the coolant pump 14, so that the coolant must take the way through the cooler. The risk of overheating of the connected internal combustion engine 21 is thereby excluded. The first valve 16 is open as long and clears the way to the coolant pump 14 as long as liquid coolant flows around it. The first valve essentially has the task of ensuring that the coolant pump 14 only sucks in liquid coolant. If, for example, the liquid coolant in the condenser has dropped to a level during the long journey in the full load range, which just keeps the first valve 16 in the open position, it can happen in extreme situations, for example when cornering quickly, that the remaining coolant is caused by flying forces from the suction area of the coolant pump 14 is displaced. In this case, the first valve 16 closes the passage from the coolers to the coolant pump, so that the coolant pump 14 does not draw in vaporous coolant, which can lead to cavitation in the pump and its destruction. Instead, the coolant pump 14 temporarily transports liquid coolant from the expansion tank 1 and leads it to the internal combustion engine 21 for cooling. Only when there is enough liquid coolant in the coolers again, does the first valve 16 open and releases the passage from the coolers to the coolant pump 14. The check valve 15 has the task of not returning the coolant in the coolant discharge line 12 back to the cooler to flow. A sufficient fluid level within the internal combustion engine 21 is then guaranteed at all times.

In FIG. 2, in contrast to FIG. 1, the partition 4 is supported on a compression spring 18, the spring chamber 6 being connected to a suction system 22 via a vacuum line 19 in which a shut-off valve 20 is arranged. However, there is also the possibility of connecting the vacuum line 19 to the suction system of the internal combustion engine 21 or, if the internal combustion engine works according to the diesel principle, to the vacuum of the brake system of the vehicle. The arrangement of the components shown here can influence the system pressure in the cooling system 3, as a result of which the cooling characteristic curve can be adapted to the respective operating states of the internal combustion engine 21. In full load operation in particular, the system pressure in the cooling system 3 can be reduced in order to achieve a lower boiling temperature of the coolant. The earlier evaporation of the coolant brings about greater cooling and better protection against overheating of the internal combustion engine 21.

FIG. 3 shows an internal combustion engine 21 with a cooling system 3, which essentially corresponds to FIG. 2. 3 differs from FIG. 3 in that a bypass 25 and an expansion thermostat 24 are arranged in the cooling system 3. The internal combustion engine 21 has reached its optimal operating temperature and the expansion thermostat 24 has closed the bypass 25. At the same time, the expansion thermostat 24 has released the coolant outlet from the convection cooler 8. The liquid coolant is thereby passed to the convection cooler 8 and the gaseous coolant through the condensation cooler 7 and cooled. The cooled coolant is then fed back to the internal combustion engine 21 via the coolant drain line 12. This allows the temperature of the through the coolant drain line 12 discharged coolant can be adapted even better to certain operating points of the internal combustion engine 21. An adaptation to components which are arranged in the coolant drain line 12 and through which the coolant flows is also better possible with this arrangement. Components through which the coolant flows and which are arranged in the coolant discharge line 12 can be formed, for example, by the vehicle interior heating and / or an oil cooler, which are not shown here. Another advantage that results in the system shown here is that the cooling system 3 has a more constant operating behavior and the interference, especially in comparison to components installed parallel to the cooler, is greatly reduced. In addition, there is a better effectiveness of, for example, the vehicle interior heating due to a larger coolant throughput.

FIG. 4 shows an evaporation-cooled internal combustion engine 21, with a cooling system 3, which has an expansion thermostat 24, similar to the system from FIG. 3. The cooling system 3 in this figure is a cold, steam-free cooling system. In this state, the cooling system 3 can easily be filled through the filler neck 23. When the filler neck is open, the vent line 26 is also open. The vehicle interior heating, for example, can also be connected to this line. The second valve 17, in the form of a float valve, is open, while the third check valve 27, which is connected downstream of the condensation cooler 7, is closed. The liquid coolant is fed to the internal combustion engine 21 under thermostat control. The coolant pump 14 can for example, for faster heating of the internal combustion engine during the warm-up phase. In addition, there is the possibility of continuing to run the coolant pump 14 after the internal combustion engine has been switched off, so that the afterheating problem of a suddenly switched off internal combustion engine 21, for example after long full load runs, can be avoided. The expansion thermostat 24 closes the passage through the convection cooler 8, and the liquid coolant moves in a small circuit through the bypass in the direction of the coolant drain line 12. In this case, the expansion tank 1 has not yet taken up any liquid coolant.

5, the amount of heat supplied is smaller than the amount of heat that can be removed. As soon as steam is generated in the cooling system 3 during operation of the internal combustion engine 21, the pressure rises, the coolant is displaced into the expansion tank 1 and the resulting steam flows through the condensation cooler 7 until an equilibrium state occurs in which the released condenser area is sufficient to compensate for that from the internal combustion engine 21 dissipate heat given off to the coolant. The liquid level in the condensation cooler 7 and in the region of the second valve 17 fluctuates in accordance with the heating power of the internal combustion engine 21 and the condenser efficiency which is dependent on the driving speed and the ambient temperature. The second valve 17, which is designed as a float valve, opens and closes depending on the liquid level. 5 it is shown in the open position. As soon as the second valve 17 closes, the suction of the coolant pump 14 creates a differential pressure at the third check valve 27, which gradually brings it into the open position. In this case, the condenser cooler becomes liquid 7 and / or sucked out of the liquid coolant-containing space 5 of the expansion tank 1. This behavior means that all liquid levels remain largely constant under steady-state operating conditions and quickly adapt to the various operating conditions. The expansion thermostat 24 regulates the coolant mass flow from the bypass 25 and the convection cooler 8 in the direction of the coolant pump 14 as a function of the ambient temperature of the coolant Has shifted towards the spring chamber 6 and reduced it. Depending on the spring characteristic of the compression spring 18, the system pressure in the cooling system 3 can be varied and influenced.
Fig. 6 shows the extreme case for which the cooling system 3 must be designed. The amount of heat supplied is equal to the amount of heat that can be removed. The vapor volume, in particular in the condensation cooler 7, has increased further and displaced liquid which has been taken up in the coolant-containing space 5 of the expansion tank 1. The spring chamber 6 has been further reduced in comparison to the variants shown in FIGS. 4 and 5. The lowering of the liquid level in the area of the second valve 17 closes it, as shown here by way of example. The suction pressure of the coolant pump 14 causes a negative pressure in the connecting line 2, whereby the third check valve 27 opens.

In the condensation cooler 7, as shown in FIGS. 1 to 3, a first valve can be arranged, which is designed as a float valve and in extreme driving situations, for example fast cornering, ensures that the coolant pump is not gaseous coolant but liquid coolant from the Expansion tank 1 sucks. In order to avoid a reduction in the antifreeze concentration of the coolant in the condensation cooler 7, the feed line is constructed in such a way that the vaporous coolant entrains liquid components and feeds it to the condensation cooler 7. This liquid coolant with an antifreeze content is returned to the cooling circuit in the condensation cooler 7 through a condensate return 10 according to FIGS. 1 to 3. The systems shown in FIGS. 1 to 6 have ventilation lines 26 so that the cooling system 3 can be filled without problems. The filler neck 23 in FIGS. 1 to 6 is provided with a cover which contains a pressure relief valve and opens in the direction of the atmosphere at critical system pressure.

In summary, it follows that the cooling system 3 is extremely easy to fill with coolant, that the system has a very high efficiency with excellent performance characteristics due to its design, has significant advantages over known systems at particularly low outside temperatures and is highly reliable due to the relatively simple principle of operation and easy assembly points.

REFERENCE SIGN LIST:

1

surge tank

2nd

Connecting line

3rd

Cooling system

4th

partition wall

5

Room containing liquid coolant

6

Spring chamber

7

Condensation cooler

8th

Convection cooler

9.7

Coolant passage lines condensation cooler

9.8

Coolant passage lines for ready-made coolers

10th

Condensate return

11

Coolant supply line

12

Coolant drain line

13

first check valve

14

Coolant pump

15

second check valve

16

first valve

17th

second valve

18th

Compression spring

19th

Vacuum line

20th

Check valve

21

Internal combustion engine

22

Suction system

23

Filler neck

24th

Expansion thermostat

25th

bypass

26

Vent line

27th

third check valve

Claims (17)

Evaporative-cooled internal combustion engine, in which a cooling system through which a liquid coolant can flow and which can be pressurized is connected to an expansion tank and a cooler, characterized in that the expansion tank (1) is always connected to one during operation of the internal combustion engine (21) by means of a connecting line (2) zone of the cooling system (3) filled with liquid coolant and which is assigned to the expansion tank (1) at least one relatively movable, liquid-tight partition (4) which divides the expansion tank (1) into a liquid coolant-containing chamber (5) and a spring chamber (6) divided. Internal combustion engine according to claim 1, characterized in that the cooling system (3) contains at least one condensation cooler (7). Internal combustion engine according to claim 2, characterized in that the condensation cooler (7) is assigned a convection cooler (8) in parallel. Internal combustion engine according to claim 2 or 3, characterized in that the condensation cooler (7) has vertical coolant passage lines (9.7). Internal combustion engine according to one of claims 1 to 4, characterized in that a condensate return (10) is associated with the condensation cooler (7). Internal combustion engine according to one of claims 1 to 5, characterized in that the cooling system (3) is provided with a coolant inlet line (11) and a coolant outlet line (12) and is completely filled with liquid coolant in the case of steam-free operation. Internal combustion engine according to claim 6, characterized in that a first check valve (13) is arranged between the coolant inlet line (11) and the coolant outlet line (12), which opens only in the direction of the coolant outlet line (12). Internal combustion engine according to claim 6, characterized in that the coolant drain line (12) is preceded by an expansion thermostat (24). Internal combustion engine according to claim 8, characterized in that the expansion thermostat (24) is associated with the convection cooler (8) and a bypass (25) adjacent to the convection cooler (8) and the coolant mass flow from the convection cooler (8) and bypass (25) in the direction of the coolant drain line (12) regulates. Internal combustion engine according to one of claims 6 to 9, characterized in that a coolant pump (14) is arranged in the coolant drain line (12) and in that the coolant pump (14) is assigned a second check valve (15) which is only in the direction of the internal combustion engine (21 ) opens. Internal combustion engine according to claim 10, characterized in that a first valve (16) is connected upstream of the coolant pump (14). Internal combustion engine according to one of claims 2 to 11, characterized in that a second valve (17) is connected upstream of the condensation cooler (7). Internal combustion engine according to claim 11 or 12, characterized in that the first (16) and the second valve (17) are designed as float valves. Internal combustion engine according to one of claims 1 to 13, characterized in that the partition (4) consists of a piston. Internal combustion engine according to one of claims 1 to 14, characterized in that the partition (4) is supported on a compression spring (18) arranged in the spring chamber (6). Internal combustion engine according to one of claims 1 to 15, characterized in that the spring chamber (6) is connected to the suction system of the internal combustion engine (21) by means of a vacuum line (19) and that the vacuum line (19) can be closed by at least one shut-off valve (20) . Internal combustion engine according to claim 16, characterized in that a vacuum accumulator is assigned to the vacuum line (19).

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