EP0726386A1 - Tank for expansion and de-acration for a cooling circuit of an internal combustion engine - Google Patents

Abstract

The tank consists of two communicating compartments (5, 6), the first having a wall with an inner cylindrical surface and at least one tangential inlet (25) at the top to centrifuge the incoming liquid, while the second has an outlet (32) at the bottom for the degassed liquid and a partition (41, 42) to damp the swirling motion of the liq. The two compartments communicate with one other through apertures (20) at the bottom of the first compartment (5). The second compartment has a cylindrical wall (10) lying coaxially with the first compartment, and two hemispherical ends (11, 31). The tank is made from a moulded plastic such as translucent polypropylene with graduations on its outer surface to allow the liquid level to be monitored.

Description

The present invention relates to an expansion and degassing tank for the coolant of an internal combustion engine, and in particular of an engine fitted to a motor vehicle.

Such a tank is an important element of the cooling circuit.

Indeed, it ensures the separation of gases, in particular of the air which is in solution in the liquid, and whose presence in the cooling circuit is detrimental for its proper functioning.

The reservoir also constitutes a reserve capacity making it possible to compensate for losses by micro-leaks from the circuit, in particular by lack of tightness of the various fittings with which the circuit is provided. It also constitutes an expansion volume capable of absorbing the expansion of the coolant as a function of the temperature and pressure conditions. It is also used to fill the circuit and to control the coolant level.

Finally, it ensures the charging and pressurization of the cooling circuit, this pressurization being regulated by a shutter plug acting as a calibrated valve.

The objective of the present invention is to provide an expansion and degassing tank which is very effective, while being of a simple design, of a moderate cost price, having a small footprint and adapting without difficulty. to different models of engines and cooling circuits, as well as to different models of vehicles in the case of an application to the automotive industry.

In traditional expansion and degassing tanks, the separation of the gas and liquid phases takes place under the effect of gravity, the Archimedes' push causing the gases, lighter than the liquid, to rise to the surface of the latter. ci, in the upper part of the tank.

It is also known, for example from document FR-A-2 317 489, to subject the liquid entering the reservoir to a vortex movement, which achieves a separation of the liquid and gaseous phases by centrifugal effect, more effective than gravity effect.

For this, the container 14 which is described in the aforementioned document has a liquid inlet constituted by a tube situated at the top of the container and oriented tangentially to the circular section and to the wall of the container, as can be seen in the figure. 3 of the document.

Such a device however has a relatively limited effectiveness; in addition, the liquid leaving the reservoir is still turbulent and has a certain kinetic energy, which compromises the proper functioning of the part of the cooling circuit located downstream of the container.

Document EP-A-0 561 673 relates to an expansion and degassing tank - called a water box - which is not actually formed from two communicating compartments, but which comprises a compartment containing an internal conduit. The liquid arrival in the upper part of it takes place tangentially, and the liquid is subjected to centrifugation there.

In this known device, a rib disposed in the lower part of the internal conduit is provided to promote the swirling of the liquid and facilitate its flow towards the outlet orifice.

In this embodiment, it is therefore also a dynamic (turbulent) liquid which leaves the reservoir.

The present invention relates more precisely to a reservoir formed by two communicating compartments.

Such reservoirs are already known, in particular from documents FR-A-2,579,668 and FR-A-2,600,117.

The device described in FR-A-2 579 668 has a general shape of revolution, of vertical axis. It is a tank comprising two parts, namely an upper part into which arrives the portion of the coolant which comes from the cylinder head and / or the radiator, and a lower part in which arrives the portion of the coolant. coming from the vehicle heating circuit, these two parts communicating through an opening provided with an anti-revolving means. The lower part is connected to an outlet pipe, through which the degassed liquid returns to the circulation pump provided in the cooling circuit.

In the upper part of this tank, degassing is done using a jet breaker. In its lower part, it is produced by centrifugation, thanks to tangential arrangements of both the supply duct (coming from the heating circuit) and the outlet duct.

It will be noted that the lower part is thin, the centrifugation of the liquid therefore taking place substantially in a horizontal plane.

Such a device is not really effective, since the amount of centrifugation to which the liquid is subjected is directly dependent on the flow rate of the liquid coming from the heating circuit; however, this flow rate is variable, possibly even being zero during certain periods of use.

In addition, centrifugation being done in a single plane, it necessarily has a very limited efficiency.

Finally, it is a moving liquid which leaves the reservoir; it is therefore a cause of turbulence and of flow and pressure inequalities in the return pipe to the fluid circulation pump, which is undesirable for the proper functioning of the entire cooling circuit.

The tank which is the subject of FR-A-2 600 117 is divided into two compartments arranged in such a way that the smallest of them is connected to a branch circuit of the main cooling circuit; this makes it possible to reduce the engine heating time thanks to a significant reduction in the volume of coolant which is used when the engine is cold, the coolant then circulating only in the bypass circuit - and therefore in the small compartment - because the main circuit is cut by a thermostatic valve.

In this tank, the separation of the liquid and gas phases is done in a conventional and relatively ineffective manner, only by gravity effect.

Like the two known devices which have just been mentioned, the reservoir according to the present invention comprises two communicating compartments.

This tank is remarkable in that one of these compartments - called the first compartment - has a wall whose internal surface is a surface of revolution of vertical axis and is provided with at least one supply nozzle disposed in the upper part. and oriented in a direction substantially tangential to said surface so that the liquid to be degassed entering the first compartment is subjected to centrifugation, while the other compartment - called second compartment - is provided at its lower part with an outlet nozzle for the degassed liquid and is provided with a partitioning - known as a tranquilization - capable of opposing the gyratory movement of the liquid, said first and second compartments communicating with each other by openings located at the bottom of the first compartment, and through which the liquid passes from the latter into the second compartment.

Thus, in the first compartment there is a particularly effective degassing of the liquid, both as a result of the vortex movement (Vortex effect) and under the effect of Archimedes' push (gravity effect).

In this first compartment, the liquid to be degassed is stuck against the wall under the effect of centrifugal forces while descending by gravity inside the compartment, the particles of fluid following an approximately helical downward trajectory, of vertical axis. When the particles reach the level of the liquid contained in the reservoir, this centrifugation and the vortex movements which it generates are slowed down, the liquid still being in gyratory movement, but no longer stuck against the compartment wall. This residual rotation allows the gas bubbles to rise to the surface under the effect of Archimedes' thrust.

In the second compartment, the movement of liquid takes place, the movement of which is hampered and, at least partially, interrupted by the partitioning lining this second compartment.

It is therefore a degassed and practically static liquid (in any case non-turbulent) which will leave the tank through the outlet nozzle to serve for the loading of the cooling circuit.

This static loading of the circuit promotes the proper functioning thereof.

• la paroi dudit second compartiment a une forme de révolution, coaxiale au premier et entourant ce dernier ;
• le premier compartiment a une paroi tubulaire de forme cylindrique, tandis que la paroi du second compartiment possède une partie principale cylindrique et des portions d'extrémité hémisphériques ;
• la paroi dudit premier compartiment s'étend axialement et vers le bas jusqu'au voisinage du fond du second compartiment ;
• la paroi dudit second compartiment est formée de deux demi-coquilles ayant une forme de révolution en matière plastique moulée fixées l'une à l'autre en position tête-bêche, la paroi cylindrique du premier compartiment formant partie intégrante de l'une d'entre elles ;
• la paroi dudit premier compartiment forme partie intégrante de la demi-coquille supérieure, à laquelle elle se raccorde, de manière étanche, en partie haute, au niveau de son fond ;
• ladite demi-coquille supérieure est munie à sa partie haute d'un orifice de remplissage et d'au moins un embout d'alimentation, tous deux débouchant dans le premier compartiment ;
• ladite demi-coquille inférieure est munie, au niveau de son fond, dudit embout de sortie, ce dernier ayant une forme générale cylindrique de même axe que l'axe de révolution des demi-coquilles ;
• le cloisonnement de tranquillisation est solidaire d'une pièce discoïde s'adaptant à l'extrémité basse de la paroi tubulaire du premier compartiment pour en constituer le fond, lesdites ouvertures qui font communiquer les deux compartiments consistant en des encoches formées à ce niveau dans la paroi ;
• ce cloisonnement comprend des ailettes à encoche qui s'étendent verticalement dans la partie inférieure du réservoir, dans l'espace annulaire séparant la paroi tubulaire du premier compartiment de la paroi de la demi-coquille inférieure ;
• ce cloisonnement comprend une cloison de section en "U", à flancs verticaux, qui est située en-dessous de ladite pièce discoïde et vient en appui contre le fond de la demi-coquille inférieure, les flancs de cette cloison entourant l'orifice d'entrée de l'embout de sortie ;
• le réservoir comporte un puits de détection de niveau, solidaire de la paroi du premier compartiment et disposé à l'extérieur de ce dernier, dans la moitié inférieure du réservoir ;
• le récipient est réalisé en polypropylène moulé translucide, et il comporte sur sa paroi extérieure une graduation de lecture de niveau de liquide ;
• lesdits compartiments communiquent l'un avec l'autre à leur partie haute par un ou plusieurs orifices qui assurent l'équilibre des niveaux dans les deux compartiments.

Furthermore, according to a certain number of advantageous, non-limiting characteristics of the invention:

• the wall of said second compartment has a shape of revolution, coaxial with the first and surrounding the latter;
• the first compartment has a tubular wall of cylindrical shape, while the wall of the second compartment has a main cylindrical part and hemispherical end portions;
• the wall of said first compartment extends axially and downwards in the vicinity of the bottom of the second compartment;
• the wall of said second compartment is formed by two half-shells having a shape of revolution in molded plastic material fixed to each other in head-to-tail position, the cylindrical wall of the first compartment forming an integral part of one of between them ;
• the wall of said first compartment forms an integral part of the upper half-shell, to which it is sealingly connected, in the upper part, at its bottom;
• said upper half-shell is provided at its upper part with a filling orifice and with at least one supply nozzle, both opening into the first compartment;
• said lower half-shell is provided, at its bottom, with said outlet nozzle, the latter having a generally cylindrical shape with the same axis as the axis of revolution of the half-shells;
• the tranquilization partitioning is integral with a discoid piece adapting to the lower end of the tubular wall of the first compartment to constitute the bottom, said openings which make the two compartments communicate, consisting of notches formed at this level in the wall;
• this partitioning comprises notched fins which extend vertically in the lower part of the tank, in the annular space separating the tubular wall of the first compartment from the wall of the lower half-shell;
• this partitioning comprises a "U" section partition, with vertical sides, which is located below said discoid piece and comes to bear against the bottom of the lower half-shell, the sides of this partition surrounding the orifice 'input of the outlet nozzle;
• the reservoir comprises a level detection well, integral with the wall of the first compartment and disposed outside of the latter, in the lower half of the reservoir;
• the container is made of translucent molded polypropylene, and it has on its outer wall a scale for reading the level of liquid;
• said compartments communicate with each other at their upper part by one or more orifices which ensure the balance of the levels in the two compartments.

Other characteristics and advantages of the invention will emerge from the description and the appended drawings which represent, by way of non-limiting example, a preferred embodiment.

• la figure 1 est une vue générale en perspective, avec arrachement partiel de sa paroi externe, d'un réservoir conforme à l'invention ;
• la figure 2 représente le même réservoir coupé par un plan vertical médian, ce plan étant désigné II-II aux figures 9 et 10 ;
• les figures 3, 4 et 5 représentent, respectivement, en vue de face, vue de côté et vue de dessous l'élément de cloisonnement dont est pourvu ce récipient ;
• la figure 6 est une vue de détail, coupée par le plan horizontal VI-VI de la figure 7, de l'une des cloisons constitutives du cloisonnement de tranquillisation ;
• la figure 7 représente, à plus grande échelle, le réservoir coupé axialement, par un plan vertical décalé angulairement par rapport au plan de coupe de la figure 2, ce plan de coupe étant référencé VII-VII aux figures 9 et 10 ;
• la figure 8 est une vue de gauche de la figure 7, à échelle plus petite ;
• les figures 9, 10 et 11 représentent le réservoir coupé par des plans horizontaux qui sont référencés respectivement IX-IX, X-X et XI -XI à la figure 7 ;
• la figure 12 est une vue schématique du réservoir, coupé par un plan vertical médian, cette vue étant destinée à illustrer la manière selon laquelle s'opère le dégazage ;
• la figure 13 est une vue de dessus schématique de la partie supérieure du premier compartiment, cette vue illustrant le mouvement giratoire du liquide rentrant dans ce compartiment.

In these drawings:

• Figure 1 is a general perspective view, partially broken away from its outer wall, of a reservoir according to the invention;
• 2 shows the same tank cut by a vertical median plane, this plane being designated II-II in Figures 9 and 10;
• Figures 3, 4 and 5 show, respectively, in front view, side view and bottom view of the partition element which is provided with this container;
• Figure 6 is a detail view, cut by the horizontal plane VI-VI of Figure 7, of one of the partitions constituting the plenum partitioning;
• FIG. 7 represents, on a larger scale, the tank cut axially, by a vertical plane offset angularly with respect to the cutting plane of FIG. 2, this cutting plane being referenced VII-VII in FIGS. 9 and 10;
• Figure 8 is a left view of Figure 7, on a smaller scale;
• Figures 9, 10 and 11 show the tank cut by horizontal planes which are referenced respectively IX-IX, XX and XI -XI in Figure 7;
• Figure 12 is a schematic view of the tank, cut by a median vertical plane, this view being intended to illustrate the manner in which degassing takes place;
• Figure 13 is a schematic top view of the upper part of the first compartment, this view illustrating the gyratory movement of the liquid entering this compartment.

The expansion and degassing tank illustrated in the figures has the general shape of a body of revolution having a main central cylindrical portion, of vertical axis ZZ ' and curved upper and lower parts, for example hemispherical.

The outer shell of the tank is formed by two half-shells 1 and 3 of the same general shape, placed head to tail, and joined by flanges 13, respectively 33, constituting the edges of their opening, the opening of the half upper shell 1 being directed downwards while the opening of the lower half-shell 3 is directed upwards.

These half-shells are made of molded plastic, for example polypropylene, their connection at the flanges 13, 33 being by hot pressure (heat sealing).

The cylindrical and curved portions of the upper half-shell 1 have been designated by the references 10 and 11, and by the references 30 and 31 the cylindrical and respectively curved portions of the lower half-shell 3. The bottom 110 of the half - upper shell is provided with a cylindrical neck 12, of axis ZZ ' , acting as a filling orifice for the tank, and intended to receive, in known manner, a shutter plug forming a calibrated pressure valve (safety valve) ; still in known manner, there is provided in the wall of the neck 12 an overflow orifice 120 opening into an evacuating nozzle 14 coming from molding with the neck; the end piece 14 is arranged horizontally, radially with respect to the axis ZZ ' .

The half-shell 1 is internally integral with a cylindrical tubular wall 2, coaxial with the cylindrical part 10, and which is connected in leaktight manner to the bottom wall 110. The tubular wall 2 has a length greater than the height of the half-shell 1, and it therefore extends downwards inside the lower half-shell 3, up to the vicinity of the bottom 310 of the latter, at a certain distance from this bottom.

The internal face of the wall 2 has been designated by the reference 26.

At the upper part of the reservoir are provided two diametrically opposite tubular ends 25, which come from molding with the assembly 1, 2, and which open into the interior space of the tubular part 2. According to an important characteristic of the invention, the end pieces 25 are oriented, in a horizontal plane, in a tangential direction relative to the inner surface 26 (see Figure 13).

The openings 24 through which the end pieces 25 open out inside the wall 2 have been designated by the reference 24.

In the upper part, the wall 2 is pierced with one or more orifices 200 communicating the interior with the exterior of the tube.

The bottom portion 310 of the lower half-shell 3 is provided with a cylindrical outlet nozzle 32, of axis ZZ ' .

In its lower part, inside the half-shell 3, the wall 2 is provided on its external face with a vertical well 21, of approximately rectangular section (see FIG. 9), provided with a bottom 210. Au level of the central part of this well, the wall 2 is pierced with a small calibrated hole 22; a similar hole 23 is drilled opposite the hole 22 in the front wall of the well 21.

Finally, the wall 2 is cut at its free lower end, so as to have several notches 20 open downwards, of rectangular or square shape.

Outside of part 2, and inside of the lower half-shell 3, is installed an element 4 which is shown in detail in FIGS. 3, 4 and 5.

It is a one-piece element of molded plastic comprising a discoid part 40 whose diameter corresponds, apart from the interlocking clearance, to that of the cylindrical wall 2, this part 40 being intended to constitute the bottom thereof.

More precisely, the free edge of the cylindrical wall 2 has over its entire periphery a recessed inner portion, into which the disc 40 can fit.

On each side of the disc 40 are disposed vertical fins 42 constituted by thin lamellae, the width of which corresponds, apart from the interlocking clearance, to the space available between the wall 2 and the wall of the lower half-shell 3 when the disc 40 is in place, to form the bottom of the tubular part 2. Each fin 42 has a lateral notch 420 facing outwards.

The two fins 42 are located in the same plane, which is parallel to the axis of the discoid part 40 (axis which corresponds to the axis ZZ ' when the element 4 is in place), but does not contain this axis.

These fins 42 extend inwards, under the disc 40, to connect to a part 41; the latter consists of a partition extending downwards under the disc 40 and having a "U" cross section (see FIGS. 5 and 6).

The partition has a height corresponding to the distance which separates the free end of the tubular wall 2 from the bottom 310.

In its central part, the middle branch of this "U" has a cutout 410 opening downwards; the lateral branches of the "U" have a free edge which has a cut 411 directed downwards.

The internal face of the wall of the lower half-shell 3 is provided with two pairs of projections or slides 35 extending vertically, capable of being used for interlocking, by longitudinal translation from the top to the bottom of the fins 42. The slides 35 are notched opposite the notches 420, a notch being referenced 350 in FIG. 2.

In the bottom 310 are provided ribs 34 shaped so as to delimit a "U" groove serving to fit the partition 41 during the positioning of the element 4 in the half-shell 3.

The projections 34 are notched opposite the cutout 410 of the partition 41.

The assembly of the reservoir is done first by placing the element 4 in the lower half-shell, then by placing the upper half-shell 1 on the lower half-shell 3, the free edge of the wall 2 then coming to fit into the discoid part 40; the half-shells 1 and 3 are then fixed to each other by heat sealing.

A double-shelled tank is thus obtained, comprising a first compartment 5 delimited by the inner cylindrical wall 2, by the upper bottom 110, and by the discoid part 40, and a second compartment 6 constituted by the interior space with half-shells 1 and 3 and outside part 5 and bottom 40.

It should be noted that this reservoir consists only of three separate parts, of molded plastic such as polypropylene, the cost of which is relatively low. The material chosen is preferably transparent or translucent, so that it is possible to see the level of liquid inside the tank without opening the shutter cap. Advantageously, as illustrated in FIG. 8, graduations 100 are provided on the wall of the reservoir, which indicate the volume of liquid contained in it.

It will also be noted that the reservoir has the form of a compact box, the general cylindrical shape of which has convex ends with the advantage of withstanding internal pressure constraints well.

It is a standard gearbox that can adapt to very different types of engine.

Usually, the tank is connected to the cooling circuit of the internal combustion engine, between the cylinder head and / or radiator outlet and the engine inlet.

The inlet ends 25 and the outlet end 32 are of the standardized type, allowing their connection to the pipes of the circuit.

There are provided inside the well 21 suitable detection members, not shown, such as electrodes for example, making it possible to control that the level of the liquid contained in the reservoir remains between predetermined minimum and maximum values; if this is not the case, these detection devices generate a signal warning the user, for example by means of an indicator provided on the dashboard of the vehicle.

The coolant is introduced into the circuit through the neck 12.

The tank is placed in an upper zone of the circuit, so as to put it on load (under pressure).

The level N of the coolant is visible through the wall of the tank.

We will now explain, with particular reference to Figures 12 and 13, how this tank performs degassing of the coolant. The obturator plug, placed on the neck 12, is referenced BO and shown in phantom.

The liquid arrives in the reservoir through the nozzles 25, as is symbolized by the arrows A in FIGS. 12 and 13.

This liquid is charged with gas, and in particular with air, which have been captured in the cooling circuit, in particular in the engine or in the radiator. It opens tangentially in the upper part of compartment 5, and is therefore subjected to centrifugation, which presses it against the internal face 26 of the cylindrical wall 3. The intensity of the centrifugal forces being different on the liquid phase and on the gas phase, a rapid separation of the gases is thus obtained, which go back up into the compartment 5 and are then evacuated outside the tank by the shutter plug BO and by the overflow orifice 120.

The liquid follows an approximately helical downward trajectory symbolized by the line B. This liquid falls back into the mass of liquid L ₁ contained in the compartment 5. It is then still in rotation, but is no longer stuck to the tubular wall 2. This residual rotation, which is symbolized by the line C in the figure 12, allows the gas bubbles which are still in the liquid to rise to the surface under the effect of Archimedes' push.

According to the principle of communicating vessels, the liquid then leaves compartment 5 through the openings 20, as symbolized by the arrows E , to end up outside the tube 2, in the second compartment 6, joining the liquid L ₂ present in the latter.

In the latter, the liquid is braked by the baffled partition consisting firstly of the fins 42 arranged laterally and by the "U" partition 41 disposed under the bottom 40.

The liquid nevertheless manages to pass, in particular through the notches of fins 420 (arrows F ), through the notch 410 of the lower partition 41 (arrow F ' ) and bypassing the walls of the lower partition 41 (arrows G ). He thus arrives in space inside of the U-shaped partition 41, where the inlet orifice 321 of the outlet nozzle 32 is located.

It is therefore a non-turbulent, practically static liquid, which leaves the reservoir via the nozzle 32, as symbolized by the arrow E , for the loading of the circuit.

The role of the orifice (orifices) 200 is to allow the free comunication of air between the compartments 5 and 6, which is necessary to obtain the balance of the levels in these compartments.

It should be noted that the detection well 21 is an area of the reservoir which is not subjected to the general flow of the liquid which passes through it. The two calibrated orifices 22 and 23 provide damping for variations in the level of liquid which prevents untimely detections.

The tranquilization partitioning, which prevents the liquid leaving the reservoir via the charging tip of the circuit 32 from being in a state of turbulence also has the effect of limiting the movements of the liquid due to the accelerations which it undergoes during of the rolling of the vehicle, which thus avoids a planing of the loading orifice 320, and the aspiration of air by the latter.

A single supply nozzle 25 could be provided, instead of two, for introducing the liquid to be degassed tangentially into the compartment 5.

Claims (14)

Expansion and degassing tank for the coolant of an internal combustion engine, comprising two communicating compartments, one of which (5) - called first compartment - has a wall (2) whose internal surface (26) is a surface of revolution of vertical axis (ZZ ') and is provided with at least one supply nozzle (25) disposed in the upper part and oriented in a direction substantially tangential to said surface (26) so that the liquid to be degassed entering this first compartment (5) is subjected to centrifugation, characterized in that the other compartment (6) - called second compartment - is provided at its lower part with a nozzle (32) of outlet of the degassed liquid and is provided with a partitioning (41, 42) - called a tranquilization - able to counteract the gyratory movement of the liquid, said first and second compartments (5, 6) communicating with each other by openings (20) located in the lower part of the prem ier compartment (5), and through which the liquid passes from the latter into the second compartment (6). Tank according to claim 1, characterized in that the wall of said second compartment (6) has a shape of revolution, coaxial with the first (5) and surrounding the latter. Tank according to claim 2, characterized in that the first compartment (5) has a tubular wall (2) of cylindrical shape, while the wall (1, 3) of the second compartment has a main cylindrical part (10-30) and hemispherical end portions (11-31). Tank according to claim 3, characterized in that the wall (2) of said first compartment (5) extends axially and downwards in the vicinity of the bottom (310) of the second compartment (6). Tank according to claim 4, characterized in that the wall of said second compartment (6) is formed by two half-shells having a shape of revolution (1, 3), of molded plastic, fixed to one another in head to tail position, the cylindrical wall (2) of the first compartment forming an integral part of one (1) of them. Tank according to claim 5, characterized in that the wall (2) of said first compartment forms an integral part of the upper half-shell (1), to which it is connected, in a sealed manner, in the upper part, at its level. bottom (110). Tank according to claim 6, characterized in that said upper half-shell is provided at its upper part with a filling orifice (12) and at least one supply nozzle (25), both opening into the first compartment (5). Tank according to one of claims 5 to 7, characterized in that said lower half-shell (3) is provided, at its bottom (310), with said outlet nozzle (32), the latter having a general shape cylindrical with the same axis as the axis of revolution (ZZ ') of the half-shells. Tank according to one of Claims 5 to 8, characterized in that the said tranquilization partition is integral with a discoid piece (40) adapting to the lower end of the tubular wall (2) of the first compartment (5 ) to form the bottom, said openings (20) which communicate the two compartments (5, 6) consisting of notches formed at this level in the wall (2). Tank according to Claim 9, characterized in that the said tranquilization partition comprises notched fins (42) which extend vertically in the lower part of the tank, in the annular space separating the tubular wall (2) from the first compartment from the wall of the lower half-shell (3). Tank according to claim 9 or 10, characterized in that said tranquilization partition comprises a partition (41) of "U" section, with vertical sides, which is located below said discoid piece (40) and comes in pressing against the bottom (310) of the lower half-shell (3), the sides of this partition (41) surrounding the inlet orifice of the outlet nozzle (32). Tank according to one of claims 2 to 11, characterized in that it comprises a level detection well (21), integral with the wall (2) of the first compartment and disposed outside of the latter, in the bottom half of the tank. Tank according to one of claims 1 to 11, characterized in that it is made of translucent molded polypropylene and that it has on its outer wall a scale (100) for reading the liquid level. Tank according to one of claims 1 to 13, characterized in that said compartments (5, 6) communicate at their upper part by one or more orifices (200) ensuring the balance of the levels in the two compartments.

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