GB2403163A

GB2403163A - Cooling system expansion tank.

Info

Publication number: GB2403163A
Application number: GB0314529A
Authority: GB
Inventors: William Richard Hutchins
Original assignee: Ford Global Technologies LLC
Current assignee: Ford Global Technologies LLC
Priority date: 2003-06-23
Filing date: 2003-06-23
Publication date: 2004-12-29
Anticipated expiration: 2023-06-23
Also published as: GB0314529D0; GB2403163B

Abstract

An expansion tank 21 for the cooling system of an internal combustion engine comprises a housing 24 forming an enclosed chamber, an inlet 35 towards the top of the enclosed chamber having an inlet orifice 36, an outlet 38 towards the bottom of the enclosed chamber and a deflector 41 in the form of a vertical tubular cylinder arranged so that liquid flowing into the enclosed chamber through the inlet orifice impinges upon the deflector tangentially or at an oblique angle. The deflector may comprise a part-cylindrical tube having a vertical slot therein to provide a path for the coolant and any gasses or vapours separated therefrom and may be open at its lower end 42. The expansion tank may be substantially spherical and may be formed from an upper 26 and a lower 27 housing part conjoined along a substantially horizontal joint face 28 with the deflector formed integrally with the upper housing part. The expansion tank more efficiently degases or deaerates the cooling liquid as it enters the expansion tank than conventional designs.

Description

Cooling Systen, Expansion Tank This invention relates to expansion tanks

for the cooling systems of liquid cooled internal combustion engines.

A typical cooling system expansion tank is a closed vessel which, when the engine is at rest, is only partially filled with liquid coolant, the remainder of the space above the liquid being available for the volumetric expansion of the coolant due to heat. Coolant discharged from the engine flows into the tank above the level of liquid coolant and returns from the bottom of the tank to join the flow of coolant returned to the engine. Such an expansion tank also serves as a means of enabling gasses dissolved or trapped in the coolant to rise to the liquid surface and escape.

One problem in the design of such expansion tanks is that coolant may take a relatively direct path from the inlet to the outlet which can give insufficient opportunity for gases and vapours to separate out from the liquid before leaving the tank through the outlet. An object of the invention is to provide cooling system expansion tank which overcomes or alleviates this problem.

According to the present invention there is provided an expansion tank for the cooling system of a liquid-cooled internal combustion engine, the tank comprising a housing forming an enclosed chamber, an inlet connection on the housing for connection to a supply of coolant discharged from the engine, an outlet connection on the housing for the return of coolant to the engine, the inlet connection discharging into the chamber through an inlet orifice located towards the top of the chamber and arranged to direct a jet of incoming coolant into the chamber and the outlet connection connecting to a main outlet located at or towards the bottom of the chamber, and a deflector in the form of a generally tubular cylinder arranged in the chamber with its axis substantially vertical and such that the jet impinges on the deflector tangentially or at an oblique angle. The deflector may be open at its lower end. - 2

Preferably, the deflector is part-cylindrical, having a vertical slot which can provide an exit path for coolant and separating gases and vapours. In such a case, the deflector may be arranged with the vertical slot adjacent a wall portion of the housing such that in use the deflector directs coolant through the slot in a direction substantially parallel to the adjacent wall portion.

Conveniently, the deflector is integral with a wall portion of the housing.

In a preferred arrangement, the housing comprises two housing parts joined at a substantially horizontal joint face, the inlet connection and the inlet orifice being formed in the upper housing part and the outlet connection being formed in the lower housing 1 0 part.

The housing may have a substantially spherical outer wall.

The invention will now be described by way of example and with reference to the accompanying drawings, of which: Fig.1 is a diagrammatic representation of the cooling system of a liquid cooled internal combustion engine incorporating an expansion tank according to the invention; Fig.2 is a vertical cross-section through the expansion tank shown in Fig.1; Fig.3 is a section on the line lil-lil in Fig.2; Fig.4 is a partial view based on Fig.2 showing a modification; and Fig.5 is a view in the direction of arrow B in Fig.4.

Referring to Fig.1, an internal combustion engine 11 has a pump 12 which can deliver liquid coolant (e.g., a water/antifreeze mix) through the engine to an engine delivery line 13 and a radiator 14. Flow from the radiator 14 to the pump 12 is through a radiator return line 15 and a pump return line 16. A thermostat and bypass control valve 17 operates to control flow in the radiator return line 15 and in a bypass line 18 - 3 such that until the coolant reaches higher temperatures most of the flow of coolant from the engine 11 is through the bypass line 18 and there is no flow through the radiator 14. At higher coolant temperatures, most of the flow is through the radiator 14 and not through the bypass line 18. An expansion tank 21 has a tank feed line 22 connected to the engine delivery line 13 and a tank return line 23 connected to the pump return line 16. A heater matrix 19 for the heating a vehicle passenger compartment is also connected between the engine delivery line 13 and the pump return line.

With further reference to Figs.2 and 3, it can be seen that the expansion tank 21 comprises a housing 24 forming an enclosed chamber 25. The housing 24 is generally spherical in shape, being formed by upper and lower moulded parts 26, 27 joined at a substantially horizontal equatorial joint face 28. The housing 24 is conveniently made of engineering plastics material, e.g. polyamide, and the equatorial joint made by hot plate welding. At the equatorial joint face 28, each moulded part 26, 27 incorporates a small flange 31,32 to enable jointing pressure to be applied.

The upper housing part 26 incorporates a filler neck 34 for closure by a filler cap (not shown) which incorporates the normal pressure control valve and anti- vacuum valve. The upper housing part 26 also has an inlet connection 35 for connection to the tank feed line 22 and this discharges through an inlet orifice 36 located towards the top of the chamber 25. The housing lower part 27 has an outlet connection 37 for connection to the tank return line 23 and this connects to an outlet 38 located at the bottom of the chamber 25. The outlet 38 is shown ghosted in Fig.3 for reference.

A deflector 41 in the form of a generally tubular cylinder is arranged in the chamber 25 with its axis Y-Y substantially vertical and such that the axis X-X of the inlet orifice 36 is offset substantially from the deflector axis Y-Y. The deflector 41 extends downwards as an integral part of the upper housing part 26 and is open at its - 4 lower end 42. A vertical slot 43 is provided in the deflector 41, the deflector being arranged with the vertical slot adjacent a wall portion of the housing 24 such that in use coolant exits through the slot in the direction of arrow A in Fig.3, i.e., substantially parallel to the adjacent wall portion of the housing 24.

In use, with a cold engine 11 and cooling system, the level of liquid coolant in the expansion tank 21 will be between the H and L marks shown for reference on Fig. 2, i.e. the chamber 25 will be approximately 40% to 48% full of liquid coolant. Coolant is pumped by the pump 12 out of the engine 11 into the delivery line 13 through the tank feed line 22 and into the expansion tank 21 through the inlet orifice 36. From the inlet orifice 36 the coolant is directed as a stream or jet onto the adjacent cylindrical wall surface of the deflector 41. Because the axis X-X of the inlet orifice 36 is offset substantially from the deflector axis Y-Y, the incoming jet of coolant is substantially tangential to the adjacent cylindrical wall portion of the deflector 41 so that the jet impacts onto the housing wall at an oblique angle and the coolant swirls or rotates about the vertical axis Y-Y as it fall towards the open end 42. This swirl allows gases and vapours to separate out from the coolant.

As indicated above, the positioning of the vertical slot 43 is such that coolant is directed by the baffle 41 to exit through the slot in the direction of arrow A in Fig.3, and this promotes swirl of the main volume of coolant in the housing lower part 27. This swirl gives a further opportunity for gases and vapours to separate out from the coolant. The outlet 38 is located some distance from the defector 41 to help allow this separation and at higher flows there may be recirculation flow in the upper region of the coolant above the outlet. By directing the incoming hot coolant over the spherical wall portion adjacent the slot 43, there is a substantial area of hot coolant exposed to the air in the chamber 25 above the level of coolant and this helps to expand the air so that the design pressure of the cooling system can be achieved rapidly under normal - 6 operating conditions. This is an advantage in helping to avoid cavitation of the pump 12.

In the modification shown in Figs. 4 and 5, parts which are identical to or similar to those shown in Figs.2 and 3 carry the same reference numeral but with the addition of 100. Again, the housing is generally spherical in shape, being formed by an upper moulded part 126 and a lower moulded part (not shown), these being joined at a substantially horizontal equatorial joint face 128 formed by flange 132. The housing upper part 126 differs from the upper moulded part 26 in that the deflector 141 has a web portion 144 which connects it to the adjacent spherical wall portion. This web portion 144 facilitates the injection moulding of the upper moulded part 126. For the same reason, the lower end 142 of the deflector 141, including the web portion 144, is at an angle a to the joint face 128. - 6

Claims

1. An expansion tank for the cooling system of a liquid-cooled internal combustion engine, the tank comprising a housing forming an enclosed chamber, an inlet connection on the housing for connection to a supply of coolant discharged from the engine, an outlet connection on the housing for the return of coolant to the engine, the inlet connection discharging into the chamber through an inlet orifice located towards the top of the chamber and arranged to direct a jet of incoming coolant into the chamber and the outlet connection connecting to a main outlet located at or towards the bottom of the chamber, and a deflector in the form of a generally tubular cylinder arranged in the chamber with its axis substantially vertical and such that the jet impinges on the deflector tangentially or at an oblique angle.

2. A tank according to claim 1 wherein the deflector is open at its lower end.

3. A tank according to claim 1 or claim 2 wherein the deflector is partcylindrical, having a vertical slot which can provide an exit path for coolant and separating gases and vapours

4. A tank according to claim 3 wherein the deflector is arranged with the vertical slot adjacent a wall portion of the housing such that in use the deflector directs coolant through the slot in a direction substantially parallel to the adjacent wall portion.

5. A tank according to any preceding claim wherein the deflector is integral with a wall portion of the housing.

6. A tank according to any preceding claim wherein the housing comprises two housing parts joined at a substantially horizontal joint face, the inlet connection À 1 - 7 and the inlet orifice being formed in the upper housing part and the outlet connection being formed in the lower housing part.

7. A tank according to claim 6 when dependent upon claim 5 wherein the deflector is integral with the upper housing part.

8. A tank according to any preceding claim wherein the housing has a substantially spherical outer wall.

9. An expansion tank for the cooling system of a liquid-cooled internal combustion engine and substantially as described herein with reference to the accompanying drawings.