This invention relates to a compensating tank for a cooling circuit of an internal combustion engine.
German Laid Open Document DE 100 21 180 A1 discloses a compensating tank of a cooling circuit of an internal combustion engine in which means are provided to reduce foaming of the coolant introduced into the compensating tank. For this purpose, the coolant is introduced via a coolant pipe into a chamber of the tank where it initially meets a U-shaped trough provided in the chamber through which the coolant can drain into the coolant reservoir after overcoming the overflow edge of the trough. The coolant flowing out of the coolant pipe first strikes an end face of the trough, however, so that there is a risk of additional foam formation. German Laid Open Document DE 40 35 284 A1 describes a compensating tank in which a coolant pipe discharges into the compensating tank below the liquid level.
Thus, an object of the invention is to provide means in a coolant compensating tank to slow down the coolant enriched with gas bubbles that exits from the coolant pipes such that foam formation in the compensating tank is largely avoided in all possible driving situations of the motor vehicle (e.g., driving uphill or downhill or driving curves with high lateral acceleration). At the same time, the coolant flowing into the compensating tank should be deaerated before it is fed back into the actual cooling circuit of the internal combustion engine.
This object is attained according to the invention.
The arrangement of the coolant pipes in the compensating tank is adjusted to the liquid level in the compensating tank so that, normally, the coolant pipes discharge at or below the liquid level. This prevents foaming essentially because the higher viscosity of the liquid in the compensating tank effectively decreases the kinetic energy of the inflowing water/gas mixture. Particularly during uphill or downhill driving, however, it is no longer ensured that the coolant exiting from the coolant pipes still discharges below or at the liquid level. In this case the curved guiding walls provided in the compensating tank ensure that the kinetic energy of the inflowing coolant is continuously decreased such that foaming is largely avoided even in these driving situations.
Other advantages and advantageous embodiments of the invention are set forth in the dependent claims and the description.
A particularly effective introduction of the inflowing liquid results if the coolant pipe discharging into the chamber with the guiding wall and its outlet opening are oriented in such a way that the outflowing coolant strikes the curved guiding wall approximately tangentially.
The compensating tank, which is advantageously made of plastic, consists of an upper and a lower shell. The guiding wall and the coolant pipe are integrated in the upper shell.
A chamber system is likewise formed in the upper shell, and the walls of the individual chambers are interconnected via openings to equalize the pressure. The coolant pipe is guided through some of the openings; these openings are dimensioned in such a way that they are simultaneously available as chamber-connecting openings.
To give the coolant flowing into the compensating tank sufficient time for defoaming, the exits of the coolant from the coolant pipe as well as the guiding wall are arranged in the rearmost chamber row-relative to the outflow connection.
In the upper shell of the compensating tank, two coolant pipes discharging into the chamber system are advantageously provided. The first coolant pipe communicates with a radiator and the second coolant pipe communicates with the water jacket of the cylinder head of the internal combustion engine.
An embodiment of the invention will now be described in greater detail, by way of example, with reference to the drawing in which:
The compensating tank 2 integrated into the cooling circuit of an internal combustion engine has an upper shell 4 and a lower shell 6, which are joined, for example, by vibration welding. The coolant flows into the compensating tank 2 through two pipes integrated in the upper shell 4, hereinafter referred to as coolant pipes 8 and 10. The return flow or outlet 12 is formed in the lower shell 6. Both the upper and the lower shell 4, 6, have a chamber system, which will now be described in greater detail. In the upper shell 4, in the present example, there are twelve chambers 14a to 14l, which are formed by transverse and longitudinal walls 15a to 15i and 16a to 16h rising from the bottom of the upper shell 4. The two coolant pipes 8 and 10 introduced into the upper shell 4 are guided through openings 17a to 17c and, respectively, 17d to 17f made in the transverse walls 15a to 15c and, respectively, 15g to 15i up to the two rearmost chambers 14d and 141. The openings 17a to 17c and 17d to 17f are larger than the outside diameters of the coolant pipes 8 and 10, such that the chambers 14a to 14d and 14i to 14l are interconnected via the openings 17a to 17c and 17d to 17f. The two coolant pipes 8, 10 are fixed in the upper shell 4 by plastic brackets 18a to 18e formed out of the bottom of the upper shell 4. In addition to the openings 17a to 17c and 17d to 17f, openings 20a to 20e connecting the chambers 14b to 141 are provided at the crossing points 19a to 19e of the transverse and longitudinal walls 15a to 15i and 16a to 16h.
Curved guiding walls 21 and 22 are provided in the two chambers 14d and 141. Their function is described in greater detail below in connection with the coolant exiting from the coolant pipes 8, 10. The two guiding walls 21, 22, analogous to the fixation brackets 18a to 18e, are formed from the bottom of the upper shell 4 as integral components and are further anchored to the walls of the chamber system. The upper shell 4 has an opening 24 provided with an internal thread, which receives a relief and vacuum valve (not depicted).
Analogous to the chamber system provided in the upper shell 4, the lower shell 6 is likewise divided into individual chambers 26a to 261, the size or dimensioning of which essentially corresponds to the chambers 14a to 141 provided in the upper shell 4. The chambers 26a to 261 are again divided by corresponding transverse walls 27a to 27i and longitudinal walls 28a to 28h. Openings 29a to 29i and, respectively, 30a to 30g are provided in both the transverse walls 27a to 27i and in the longitudinal walls 28a to 28h (except for 28b).
It is generally known that the compensating tank 2 is used to cushion or maintain the pressure in the cooling system of the internal combustion engine. A further function of the compensating tank is to ensure deaeration of the cooling system. For this purpose, it has to be ensured that air flowing into the compensating tank 2 together with the coolant through the deaeration lines 8 and 10 remains in the compensating tank 2 and foaming of the coolant is inhibited. The configuration of the interior structure of the compensating tank 2 ensures these functions, which will now be described in greater detail. The coolant pipes 8, 10, which are connected, respectively, with the radiator and the water jacket of the cylinder head of the internal combustion engine, conduct the coolant specifically into the rearmost chambers 14d and, respectively, 14l—relative to the outlet 12 provided in the lower shell 6. If the vehicle is in its normal position, i.e., if it is not strongly tilted about its longitudinal and/or transverse axis and if no significant longitudinal or transverse accelerations occur, the position of the coolant pipes 8, 10 relative to the liquid level in the compensating tank 2 is adjusted such that the ends of the coolant pipes 8, 10 discharge at or below the liquid level. This prevents foam formation essentially because the higher viscosity of the liquid in the compensating tank effectively reduces the kinetic energy of the inflowing coolant or the water/gas mixture. The approximately tangential impact of the outflowing coolant on the two curved guiding walls 21, 22 is a further means to reduce the kinetic energy and thereby to reduce foaming.
Particularly during uphill or downhill driving or during acceleration of the vehicle it is no longer ensured, however, that the coolant exiting from the coolant pipes still discharges into the compensating tank 2 below or at the liquid level. In this case, the curved guiding walls 21, 22 provided in the compensating tank 2 ensure that the kinetic energy of the coolant flowing into the two chambers 26d and 26l is not reduced abruptly, but gradually as a result of the spiral flow of the coolant, such that foaming is largely avoided in these driving situations as well.
As the arrows indicate in
In addition to providing a coolant defoaming function, the chambers prevent the coolant from sloshing back and forth when the motor vehicle or the engine is at an angle. At the same time, the chamber system contributes to an overall stiffening of the compensating tank.
The horizontal marking ribs 31, 32 shown in Figure serve to indicate the coolant filling level. The marking rib 31 shows the maximum cold filling volume Vmax and the marking rib 32 the minimum cold filling volume Vmin.
Number | Date | Country | Kind |
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102 31 480.2 | Jul 2002 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP03/07104 | 7/3/2003 | WO | 8/17/2004 |