Storage tank

Abstract

A storage tank for storing a liquid comprises a main storage chamber; an internal sub chamber located within the storage tank; and a reclosable filling opening for enabling filling of liquid into the main storage chamber and internal sub chamber. An overflow level of the internal sub chamber is located substantially at or above a predetermined fill level of the main storage chamber. The reclosable filling opening and the internal sub chamber are arranged in a substantially superposed relationship in a vertical direction, such that a substantially or entirely vertical stream of liquid filling the storage tank via the reclosable filling opening is configured to enter the internal sub chamber. A method for filling a storage tank with a liquid, a method for manufacturing a storage tank for storing a liquid, and a system comprising a storage tank and a filling nozzle are also described.

Claims

1. A storage tank for storing a liquid, wherein the storage tank comprises: a main storage chamber; an internal sub chamber located within the storage tank; a reclosable filling opening for enabling filling of liquid into the main storage chamber and internal sub chamber; and an inlet/outlet located in an exterior wall of the main storage chamber and being configured to be connected to a cooling circuit of a liquid cooling system; wherein an overflow level of the internal sub chamber is located substantially at or above a predetermined fill level of the main storage chamber, and wherein the reclosable filling opening and the internal sub chamber are arranged in a substantially superposed relationship in a vertical direction, such that a substantially or entirely vertical stream of liquid filling the storage tank via the reclosable filling opening is configured to enter the internal sub chamber before overflowing into the main storage chamber.

2. The storage tank according to claim 1, wherein the predetermined fill level of the main storage chamber is indicated on the storage tank by means of at least one fill level marking.

3. The storage tank according to claim 2, wherein the at least one fill level marking includes an upper fill level marking indicating a first fill level and a lower fill level marking indicating a second fill level, wherein the first fill level corresponds to a larger filling volume than the second fill level, and wherein an overflow level of the internal sub chamber is located at or above the lower fill level marking.

4. The storage tank according to claim 1, wherein the storage tank comprises a fill level sensor located within the main storage chamber, and wherein the predetermined fill level of the main storage chamber is indicated by means of the fill level sensor.

5. The storage tank according to claim 1, wherein the storage tank is configured such that liquid will flow from the internal sub chamber to the main storage chamber upon overflow of the internal sub chamber.

6. The storage tank according to claim 1, wherein the internal sub chamber has a storage capacity in the range of 1 to 100 milliliters.

7. The storage tank according to claim 1, wherein the storage tank comprises an exterior wall that defines the main storage chamber, and wherein the internal sub chamber is displaced from the exterior wall on all sides thereof.

8. The storage tank according to claim 1, wherein the storage tank comprises an exterior wall that partly defines the main storage chamber and partly defines the internal sub chamber.

9. The storage tank according to claim 1, wherein an internal partition wall within the storage tank divides the main storage chamber from the internal sub chamber.

10. The storage tank according to claim 1, wherein the internal sub chamber is defined by a hollow rigid body with an open upper end and a closed lower end, and the internal sub chamber is formed between the upper and lower ends.

11. The storage tank according to claim 10, wherein the storage tank comprises an upper injection moulded tank element having a closed end and an open end and a lower injection moulded tank element having a closed end and an open end, wherein the upper and lower tank elements are permanently connected to each other with their open ends facing each other such as to form a single piece storage tank, wherein the hollow rigid body is integrally formed with the upper tank element.

12. The storage tank according to claim 10, wherein the open end of the upper tank element is oriented in a direction opposite a direction of orientation of the open upper end of the hollow rigid body.

13. The storage tank according to claim 1, wherein the storage tank is an expansion tank for storing a cooling liquid of a liquid cooling system.

14. A system comprising-a storage tank according to claim 1 and a filling nozzle for filling the storage tank with a liquid, wherein the filling nozzle comprises: an abutment surface for abutting the reclosable filling opening of the storage tank, and a spout with an opening for filling liquid into the storage tank and sucking out superfluous liquid from the storage tank, wherein the opening of the filling nozzle is located within the internal sub chamber when the filling nozzle is sealingly inserted into the reclosable filling opening and the abutment surface abuts the reclosable filling opening.

15. A system comprising: a storage tank comprising: a main storage chamber; an internal sub chamber located within the storage tank; and a reclosable filling opening for enabling filling of liquid into the main storage chamber and internal sub chamber; wherein an overflow level of the internal sub chamber is located substantially at or above a predetermined fill level of the main storage chamber; wherein the reclosable filling opening and the internal sub chamber are arranged in a substantially superposed relationship in a vertical direction, such that a substantially or entirely vertical stream of liquid filling the storage tank via the reclosable filling opening is configured to enter the internal sub chamber; and a filling nozzle comprising: an abutment surface for abutting the reclosable filling opening of the storage tank, and a spout with an opening for filling liquid into the storage tank and extracting superfluous liquid from the storage tank, wherein the opening of the filling nozzle is located within the internal sub chamber when the filling nozzle is inserted into the reclosable filling opening and the abutment surface abuts the reclosable filling opening.

16. The system according to claim 15, wherein the storage tank comprises an exterior wall that defines the main storage chamber, and wherein the internal sub chamber is displaced from the exterior wall on all sides thereof.

17. The system according to claim 15, wherein the storage tank comprises an exterior wall that partly defines the main storage chamber and partly defines the internal sub chamber.

18. The system according to claim 15, wherein the storage tank is configured such that, after the main storage chamber and internal sub chamber have been completely filled with the liquid, excess liquid may be extracted via a filling nozzle extended into the internal sub chamber of the storage tank such that once the fill level of the excess liquid within the main storage chamber is reduced to the overflow level of the internal sub chamber, the excess liquid within the internal sub chamber will be extracted.

19. The storage tank according to claim 1, wherein the storage tank is configured such that, after the main storage chamber and internal sub chamber have been completely filled with the liquid, excess liquid may be extracted via a filling nozzle extended into the internal sub chamber of the storage tank such that once the fill level of the excess liquid within the main storage chamber is reduced to the overflow level of the internal sub chamber, the excess liquid within the internal sub chamber will be extracted.

20. The storage tank according to claim 3, wherein the storage tank is configured such that, after the main storage chamber and internal sub chamber have been completely filled with the liquid, excess liquid may be extracted via a filling nozzle extended into the internal sub chamber of the storage tank such that once the fill level of the excess liquid within the main storage chamber is reduced to the overflow level of the internal sub chamber, the excess liquid within the internal sub chamber will be extracted.

21. The storage tank according to claim 9, wherein the storage tank is configured such that, after the main storage chamber and internal sub chamber have been completely filled with the liquid, excess liquid may be extracted via a filling nozzle extended into the internal sub chamber of the storage tank such that once the fill level of the excess liquid within the main storage chamber is reduced to the overflow level of the internal sub chamber, the excess liquid within the internal sub chamber will be extracted.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) The foregoing will be apparent from the following more particular description of the example embodiments, as illustrated in the accompanying figures in which like references characters refer to the same parts throughout the different views. The figures are not necessarily to scale, emphasis instead being placed upon illustrating the example embodiments through schematic figures.

(2) FIG. 1 shows a schematic of a storage tank connected to the cooling system of an engine,

(3) FIGS. 2A-2E show side cut views of a storage tank being filled at stages A through E,

(4) FIG. 3A shows a top view of a storage tank from above,

(5) FIG. 3B shows a cross-section of a storage tank with an internal sub chamber from above,

(6) FIGS. 4A-4E show side cut views of a storage tank with an internal sub chamber being filled at stages A through E, and

(7) FIG. 5 shows a side cut views of an exploded view of a storage tank,

(8) FIG. 6 shows a side cut view of example tool for manufacturing the storage tank,

(9) FIG. 7 shows a side cut view of an alternative embodiment of the storage tank,

(10) FIG. 8 shows a side cut view of a further alternative embodiment of the storage tank,

(11) FIG. 9 shows a side cut view of yet an alternative embodiment of the storage tank, and

(12) FIG. 10 shows a side cut view of a storage tank having a single fill level marking at a height corresponding to the overflow level of the internal sub chamber.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

(13) Various aspects of the disclosure will hereinafter be described in conjunction with the appended drawings to illustrate and not to limit the disclosure, wherein like designations denote like elements, and variations of the described aspects are not restricted to the specifically shown embodiment, but are applicable on other variations of the disclosure.

(14) With reference to FIG. 1 of the drawings, a schematic of a storage tank 20 being connected to the cooling system 10 of an engine 11, such as a combustion engine. The cooling system 10 and engine 11 may for example be installed in of a vehicle. The illustrated example cooling system 10 includes a pump 12, a thermostat valve 14 and a heat exchanger 13. Cooling liquid may be made to flow in the cooling system by means of the pump 12, such that cooling liquid being heated up by the engine 11 flows to the heat exchanger where it cools down, and back via the thermostat valve 14 and pump 12 to the engine 11. Excess cooling liquid 40 is stored in the storage tank 20. If the thermostat valve 14 determines that the temperature of the cooling liquid 40 is below a predetermined temperature, the thermostat valve allows cooling liquid 40 to by-pass the heat exchanger 13, such as to heat up faster. If the temperature of the cooling liquid 40 is at or above a predetermined temperature, the thermostat valve closes the by-pass line 15 is closed, and the liquid 40 flows through the heat exchanger 13 which cools the liquid 40 before proceeding through the thermostat valve towards the storage tank 20, pump 12 and engine 1.

(15) The illustrated example embodiment of a cooling system merely describes an example embodiment of a cooling system and many variations are possible within the scope of the claims. Similarly, the storage tank is shown as a closed reservoir, but ventilation may be included to compensate for variable amount of air within the storage tank. A single or multiple inlet/outlet pipes may be used for conveying fluid to and from the storage tank.

(16) FIGS. 2A through 2E show a storage tank 20 without an internal sub chamber which is being filled to achieve a predetermined fill level. The storage tank 20 may be installed in a cooling system as shown in FIG. 1. FIG. 2A shows a storage tank 20 which comprises a main storage chamber 21, a reclosable filling opening 23, a filling opening cap 24, and an inlet/outlet 29 connected to a cooling circuit. The storage tank 20 also comprises an upper fill level marking 26 indicating a maximum fill level of the main storage chamber 21 and a lower fill level marking 27 indicating a minimum fill level of the main storage chamber 21. Upon initial filling, i.e. after finalised assembly of the cooling system 10 but before first filling of the storage tank 20, the storage tank 20 is closed. The reclosable filling opening 23 is adapted to receive a filling nozzle 25.

(17) The storage tank 20 is intended to act as an expansion tank. Apart from storing the cooling liquid 40 and serving as a filling point for refilling cooling liquid 40, the storage tank 20 allows for room for the cooling liquid 40 to expand, which is a common effect as the temperature of the cooling liquid 40 increases.

(18) In FIG. 2B, the filling opening cap 24 has been removed from the reclosable filling opening 23, and a filling nozzle 25 has been inserted into the storage tank 20, extending a distance therein. An abutment surface 25a of the filling nozzle 25 abuts an upper rim of the reclosable filling opening 23, such that the reclosable filling opening 23 becomes closed. After this, the filling nozzle 25 is used to supply liquid 40 into the main storage chamber 21 of the storage tank 20 in order to fill the main storage chamber 21 completely.

(19) In FIG. 2C, the storage tank 20 has been supplied with liquid 40 through the filling nozzle 25 until the main storage chamber 21 is filled with liquid 40. In the next step, the filling nozzle 25 will be used for extracting, i.e. sucking out, the liquid 40 from the main storage chamber 21 for quickly and easy attaining a certain fill level.

(20) In FIG. 2D, the filling nozzle 25 has been used to withdraw liquid 40 from the main storage chamber 21. By withdrawing as much liquid 40 as possible, the resulting fill level of the main storage chamber 21 will be at the same level as the extension of the filling nozzle 25 into the main storage chamber 21. In the storage tank 20 shown in FIGS. 2A-E, the filling nozzle 25 extends to a point above the upper fill level marking 26. Thereby, the resulting fill level of the storage tank 20 is above the predetermined fill level, which in FIG. 2D corresponds to the upper fill level marking 26.

(21) In FIG. 2E, the filling nozzle 25 has been removed from the storage tank 20, and the reclosable filling opening 23 has been closed by the filling opening cap. After operation of the engine and cooling system for a short time period, air that was initially trapped in the cooling system upon assembly of the cooling system and engine has become evacuated and replaced with liquid from the storage tank 20. The fill level has therefore dropped a certain level, for example in the range between the upper fill level marking 26 and lower fill level marking 27. However, since the manufacturer wishes to have the fill level of the storage tank at the upper fill level marking 26 during a substantial amount of time after delivery of the engine cooling system to a customer, the final fill level depicted in FIG. 2E may be deemed unsatisfactory.

(22) FIGS. 3A and 3B show a top view of an example embodiment of a storage tank 20 according to the invention. FIGS. 4A through 4E show the same storage tank 20 as FIGS. 3A and 3B, but in a cut side view. The side cut of the view in FIGS. 4A-4E runs along the first plane 31 shown in FIG. 3A, essentially running along a centre line 33 of the storage tank 20. FIG. 3B shows a top cut view of the storage tank 20 along the second plane 32 indicated in FIG. 4A.

(23) FIG. 3A shows the storage tank 20 and the filling cap 24. The storage tank 20 comprises two markings 26, 27. The first marking 26 shows the maximum fill level of the storage tank 20, and the second marking 27 shows the minimum fill level of the storage tank 20. While the filling cap 24 is shown in FIG. 3A to be hexagonal or the like for enabling good grip to a user. The cap 24 can have any shape suitable to allow it to be fastened by either tools or human hands. Shown in FIG. 3A is also a line showing the first plane 31 in which the side cut view of FIGS. 4A-4E is cut.

(24) FIG. 3B shows a top cut view of the storage tank 20 along a second plane 32. The extension of said second plane 32 is shown in FIG. 4A. FIG. 3B shows an internal sub chamber 22 which is located directly beneath the reclosable filling opening 23. In other words, the internal sub chamber 22 is vertically superposed relatively the reclosable filling opening 23, such that a substantially or entirely vertical stream of liquid filling the storage tank via the reclosable filling opening is configured to enter the internal sub chamber when the storage tank is positioned in an angular orientation corresponding to an installation position of the storage tank within a vehicle. Thereby, when the filling nozzle 25 is inserted into the reclosable filling opening 23, and liquid 40 enters the storage tank 20 via said filling nozzle 25, the liquid 40 will mainly enter the internal sub chamber 22.

(25) FIGS. 4A through 4E show the process of filling a storage tank 20 with liquid 40. FIGS. 4A through 4E are shown in a side cut view along the first plane 31. The storage tank 20 comprises the same components as the storage tank 20 shown in FIGS. 2A through 2E, with the addition of the internal sub chamber 22. The internal sub chamber 22 is formed by a hollow rigid body 30, which comprises an open upper end 34 and a closed end 35. The hollow rigid body 30 shown in FIG. 4A-4E is displaced from the exterior wall 50 of the main storage chamber 21 on all sides thereof. Not shown are connections, essentially plastic moulded details which connect the internal sub chamber 22 to the main storage chamber 21 at points near the reclosable filling opening 23. FIG. 4A also shows the second plane 32 in which the top view cut of FIG. 3B is cut. The reclosable filling opening 23, the internal sub chamber 22 and the inlet/outlet 29 are all arranged along a vertical centre axis of the storage tank 20.

(26) The filling nozzle 25 may for example comprise a flange having an abutment surface 25a adapted to pushed against a top surface or upper rim of the reclosable a filling opening 23 of the storage tank 20. The abutment surface 25a of the filling nozzle may alternatively be adapted to contact and abut another surface associated with the reclosable a filling opening 23, such as an internal or external flange or shoulder. The filling nozzle may further comprise a spout 25c having an opening 25b, for example at the end thereof, for filling and sucking out superfluous coolant from the storage tank 20. The length d.sub.3 between abutment surface 25a and the opening 25b may be in the range of 20-150 millimeters, specifically in the range of 30-100 millimeters. The spout may be cylindrical with a diameter in the range of 5-40 millimeters, specifically in the range of 7-20 millimeters.

(27) In FIG. 4B, the filling cap 24 is removed from the reclosable filling opening 23. The filling nozzle 25 is inserted into the storage tank 20, whereby the abutment surface 25a of the filling nozzle 25 engages an upper rim of the reclosable filling opening 23, such that the reclosable filling opening 23 becomes temporarily closed. Due to the location of the internal sub chamber 22 and the length of the spout 25c, the opening 25b of the spout 25c becomes located within the internal sub chamber 22.

(28) The height h.sub.1 of the internal sub chamber 22 may be in the range of 5-100 millimeters, specifically in the range of 10-50 millimeters. The internal sub chamber 22 is further arranged to allow coolant liquid to flow out from and in to the internal sub chamber 22 from the surrounding main storage chamber 21 at least via a portion of an upper rim of the open upper end 34 of the hollow rigid body 30. Said portion of the upper rim defines the overflow level 28 of the internal sub chamber 22, and thereby also the remaining fill level when liquid is sucked out from the internal sub chamber 22 via the opening 25b of the spout 25c. The opening 25b of the filling nozzle 25 is preferably located completely within the internal sub chamber 22 for ensuring that the upper rim of the open upper end 34 of the hollow rigid body 30 finally defines the remaining fill level when liquid is sucked out from the internal sub chamber 22 via the opening 25b.

(29) The vertical distance d.sub.4 between the overflow level 28 and the exterior wall 50 of storage tank 20 in a region of the reclosable filling opening 23 may typically be less than 50 millimeters, specifically less than 30 millimeters, thereby allowing the use of a relatively long spout 25c while enabling a high fill level after filling. A distance d.sub.5 between an internal bottom of the internal sub chamber 22 and the upper rim of the reclosable filling opening 23 may be selected slightly larger than the length of the spout 25c, such that the spout 25c does not engage the internal bottom of the internal sub chamber 22 when the filling nozzle 25 is abutting the upper rim of the reclosable filling opening 23, while still enable the opening 25b of the spout 25c to be located within the internal sub chamber 22.

(30) Subsequently, the main storage chamber 21 and the internal sub chamber 22 may be filled. Because of the positioning of the internal sub chamber and the filling nozzle 25, the liquid 40 entering the storage tank 20 will first fill up the internal sub chamber 22, upon which liquid 40 will overflow from the internal sub chamber 22 into the main storage chamber 21, thus filling the main storage chamber 21.

(31) A pipe filling hose and filling nozzle 25 having a single flow path may be used, wherein the single flow path will alternatively be used for filling liquid into the storage tank 20 and sucking liquid out of the storage tank 20. Alternatively, a pipe filling hose and filling nozzle 25 having two flow paths may be used, wherein a first flow path may be used for filling liquid into the storage tank 20 and a second flow path may be used for sucking liquid out of the storage tank 20. If a multiple flow path filling nozzle 25 is used the opening of the first flow path arranged for filling liquid into the storage tank 20 may be located outside of the internal sub chamber 22.

(32) In FIG. 4C, the main storage chamber 21 and the internal sub chamber 22 have been filled. The abutment surface 25a closing the reclosable filling opening 23 may be used for ensuring that no liquid 40 will spill out of the storage tank 20. However, other sealing solutions may alternatively be used, such as for example radial sealing between the filling nozzle 25 and the reclosable filling opening 23. When the abutment surface 25a does not have a sealing functionality the abutment surface 25a may still have a positioning functionality for ensuring that the filling nozzle 25 is positioned in a correct axial position when filling the storage tank 20, i.e. ensuring that the filling nozzle 25 is inserted with a correct distance into the reclosable filling opening 23 or storage tank 20.

(33) In FIG. 4D, the liquid 40 of the internal sub chamber 22 has been essentially sucked out by means of the opening 25b of the filling nozzle 25. Initially during the suction phase, liquid 40 from the internal sub chamber will be removed while liquid from the surrounding storage tank 20 will refill the internal sub chamber 22. However, once the fill level within the storage tank 20 reaches the overflow level 28 of the internal sub chamber 22, the filling nozzle 25 will only remove liquid 40 from the internal sub chamber 22, and not the remainder of the storage tank 20. This means that the resulting fill level of the storage tank 20 will be equal to the overflow level 28 of the internal sub chamber 22. Once it is detected that essentially no further liquid is sucked out from the internal sub chamber 22 the suction phase may be terminated. The fill level of the storage tank 20 can be assumed to be at the overflow level 28 of the internal sub chamber 22 once no more liquid 40 can be removed from the internal sub chamber 22.

(34) The internal sub chamber 22 is preferable entirely closed and sealed at the closed end 35 of the hollow rigid body 30, but the existence of one or more small openings at the closed end 35 of the hollow rigid body 30 do not prevent the proper functionality of the disclosure as long as any openings at the closed end 35 are relatively small and the suction phase is relatively quick. The fill level after the suction phase will be essentially the same as when an entirely closed end 35 is used.

(35) In FIG. 4E, the filling cap 24 has been returned to a position closing the reclosable filling opening 23. After operation of the engine and cooling system for a short time period, air that was initially trapped in the cooling system upon assembly of the cooling system and engine has become evacuated and replaced with liquid from the storage tank 20. The level of replacement liquid may be predicted and it may be desirable to overfill the storage tank with an amount corresponding to the predicted required replacement liquid volume, such that the final fill level of the storage tank 20 after a certain operating time corresponds to the upper fill level marking 26, which indicates a maximum fill level.

(36) FIG. 5 shows an example embodiment how the storage tank 20 may be assembled. A single piece upper tank element 55 and a single piece lower tank element 56 may be manufactured by injection moulding. The single piece upper tank element 55 has a closed end 57 with the reclosable filling opening 23, an open end 58 and the hollow rigid body 30. The internal sub chamber 22 is formed between the upper and lower ends 34, 35 of the hollow rigid body 30. The single piece lower tank element 56 has a closed end 59 and an open end 60 as well as a suitable position for an inlet/outlet 29 in the closed end 59. The upper and lower tank elements 55, 56 are connected to each other with their open ends 58, 60 facing each other. Thus a single piece storage tank 20 having a main storage chamber 21, an internal sub chamber 22, reclosable filling opening 23 and an inlet/outlet 29 is formed. The predetermined fill level markings 26, 27 may be formed integrally with the exterior wall 50 of the storage tank 20. The overflow level 28 of the internal sub chamber 22 is located above the predetermined fill level markings 26, 27 in FIG. 5.

(37) In the embodiment of the storage tank shown in FIGS. 3B, 4A-4E and 5, the open end 58 of the upper tank element 55 is oriented in a direction 36 opposite a direction 37 of orientation of the open upper end 34 of the hollow rigid body 30.

(38) FIG. 5 further shows an advantageous relationship between an external width d.sub.2 of the internal sub chamber 22, and an internal width d.sub.1 of the interior of the reclosable filling opening 23. When the external width d.sub.2 of the sub chamber 22 is smaller than the internal width d.sub.1 of the interior of the reclosable filling opening 23, the hollow rigid body 30 forming the internal sub chamber may be made manufactured integrally with the upper tank element 55 in a single shot injection-moulding step, as described below.

(39) An example tool used for manufacturing an upper tank element 55 by means of an injection-moulding process is depicted in FIG. 6. The tool may comprise an upper part 41 and a corresponding lower part 42, wherein the upper and lower parts 41, 42 are arranged to form a cavity 52 when forced together as shown on FIG. 6. The cavity is filled with plastic material during the injection-moulding step, thereby forming the upper tank element 55. The upper part 41 may be provided with an integrally formed projection 43 and the lower part 42 may be provided with a corresponding integrally formed recess for forming the internal sub chamber 22. The upper and lower parts 41, 42 may, in the region above the internal sub chamber, have metal-to-metal contact 44 in some circumferential areas and leaving a gap 45 in some other circumferential areas, for the purpose of forming the internal sub chamber integral with the upper tank element 55. The areas having metal-to-metal contact 44 will after manufacturing provide windows for allowing fluid entering the internal sub chamber to overflow into the main chamber, and the gap 45 in some other circumferential areas will after manufacturing provide the integrally formed connection elements permanently connecting the upper tank element 55 and hollow rigid body 30. A feed pipe 46 for feeding molten plastic material to the cavity of the injection moulding tool is schematically shown in FIG. 6.

(40) FIGS. 7 through 10 show additional alternative embodiments of the invention. FIG. 7 shows a storage tank 20 where the hollow rigid body 30 extends down to a bottom side of the exterior wall 50 of the storage tank 20, such that the exterior wall 50 of the storage tank 20 partly defines the internal sub chamber 22. The upper rim of the hollow rigid body 30 defines the overflow level 28 as before.

(41) FIG. 8 shows a storage tank 20 which comprises an internal shelf arranged below the reclosable filling opening 23. The shelf is equipped with an internal partition wall 51 which, together with the exterior wall 50 of the storage tank 20 defines the internal sub chamber 22. The shelf may be designed to have a smaller depth in the vertical direction than the remaining part of the storage tank 20.

(42) FIG. 9 shows a storage tank 20 similar to the one shown in FIG. 8, but the exterior wall 50 of the storage tank 20 projects upwardly at the edge of the shelf to define the internal sub chamber 22.

(43) FIG. 10 shows a storage tank 20 in which the overflow level 28 of the internal sub chamber 22 is equal to a predetermined fill level, which in this example embodiment is defined by means of a marking 26 on the side of the storage tank 20.

(44) Reference signs mentioned in the claims should not be seen as limiting the extent of the matter protected by the claims, and their sole function is to make claims easier to understand.

REFERENCE NUMBERS

(45) 10 Cooling system 11 Engine 12 Pump 13 Heat exchanger 14 Thermostat valve 15 By-pass line 20 Storage tank 21 Main storage chamber 22 Internal sub chamber 23 Reclosable filling opening 24 Filling cap 25 Filling nozzle 25a Abutment surface of filling nozzle 25b Opening of filling nozzle 25c Spout 26 Upper fill level marking 27 Lower fill level marking 28 Overflow level 29 Inlet/Outlet 30 Hollow rigid body 31 First plane 32 Second plane 33 Centre line 34 Open upper end 35 Closed lower end 36 Direction of orientation of open end of upper tank element 37 Direction of orientation of open upper end of hollow rigid body 40 Liquid 50 Exterior wall 51 Internal partition wall 52 Cavity 55 Upper tank element 56 Lower tank element 57 Closed end of upper injection moulded tank element 58 Open end of upper injection moulded tank element 59 Closed end of lower injection moulded tank element 60 Open end of lower injection moulded tank element