Surge tank   

Abstract: A surge tank includes a reservoir wherein the reservoir defines a coolant receiving inlet for coupling to the engine. The reservoir further defines a reservoir outlet through which the flow of coolant is returned to the engine. The coolant receiving inlet receives a flow of coolant from the engine. The surge tank further includes a plurality of objects disposed within the coolant reservoir. The plurality of objects are operatively configured to float at an upper surface of the coolant in the reservoir and to dampen the momentum of the coolant flowing from the engine.

The present disclosure relates generally to surge tanks for use in vehicles, including surge tanks that receive coolant, deaerates the coolant, and returns the deaerated coolant to the system.

In a known cooling system for an internal combustion engine, a cooling water reservoir tank is provided and is used not only for storing an overflow of cooling water but also for ensuring a recirculation of a part of the cooling water to the reservoir tank, to thereby separate and remove air and vapor from the cooling water in the reservoir tank, to thereby separate and remove air and vapor from the cooling water in the reservoir tank, whereby the cooling efficiency of the cooling system is increased.

In this type of cooling system, in general, an independent cooling water passageway connects the reservoir tank to an engine body and a radiator, and the reservoir tank is provided with a cap equipped with a relief valve which allows air or vapor held in an upper portion of the reservoir tank to be discharged to the atmosphere, when the pressure inside the reservoir tank exceeds a predetermined value, and thus prevents an excessive increase of the pressure in the cooling system. This operation also allows air to be quickly separated from the cooling water: this air is entrained in the cooling system when the cooling water is supplemented, and remains in the cooling system. The separated air is discharged by the relief valve in the reservoir tank, and thus, the cooling efficiency of the system is enhanced.

When the engine is stopped just after a high load operation, the circulation of the cooling water is stopped, and accordingly, the temperature of the cooling water becomes very high, which causes a large amount of the cooling water to be vaporized and this vapor collects in the upper portion of the cooling system (i.e. a hot soak).

Referring now to FIG. 1, a schematic diagram of a simplified example of a vehicle (not shown) having a surge tank 110 for de-aerating coolant is illustrated. In FIG. 1, the vehicle comprises an engine 112 and a radiator 114 through which coolant is circulated, at least at selected times, to cool the coolant for use in removing heat from the engine 112. Other components may also be cooled by the coolant such as a transmission 116 and an exhaust gas recirculation cooler (e.g. EGR cooler) not shown in this figure. The coolant may also be used to provide energy to or remove energy from an HVAC—heating ventilation and air conditioning—system (not shown) of the vehicle.

One specific example of a vehicle is a truck, such as a heavy duty or medium duty truck (not shown) used in long hauling operations or a truck tractor used for such purposes. Land vehicles are particularly desirable applications in which surge tanks would be used. In FIG. 1, segments of the coolant recirculation conduits are indicated by the numbers 118, 120, 122. In the example of FIG. 1, aerated coolant from the engine 112 passes via a conduit 118 to an inlet 124 to a surge tank 110. In addition, aerated coolant passes through a conduit 120 from radiator 114 to an inlet 126 to the surge tank 110, which may separate from or in common with the inlet 126 that receive aerated fluid from conduit 24. Air is removed from the coolant as it passes through the surge tank 26. The deaerated coolant is returned to the engine 112 via a conduit 122 in FIG. 1.

There are a number of reasons for de-aerating coolant. For example, poor de-aeration of coolant can result in cavitation of an engine water pump, pitting of engine liners, engine overheating, cab HVAC system failures, EGR cooler erosion, and other drawbacks. For example, modern truck engines have relatively high fluid flow rates to a surge tank, such as in excess of four gallons per minute. As a result, it becomes more difficult to de-aerate the coolant. In addition, high fluid flow rates into a surge tank can result in fracturing air bubbles into microbubbles (e.g., pin sized bubbles) which are even more difficult to remove from the coolant.

It is known to make surge tanks out of plastic for weight and cost saving purposes. However, because of the high temperatures often reached by coolant, plastic can tend to soften when used. As a result, plastic surge tanks are typically provided with reinforcing baffles 128 as shown in FIGS. 2A, 2B, and 2C. However, high coolant flow rates into surge tanks with baffles 128 increases the foaming (formation of small bubbles) when the entering liquid impacts the baffles 128. Also, because extremely small bubbles entrained in fluid are difficult to separate, bubbles formed from fracturing larger bubbles are more easily carried through a surge tank 110, resulting in poorer de-aeration of the coolant. To reduce the possibility of small foam formed bubbles entering the fluid and being carried through a surge tank 110, some engine manufacturers have issued specifications for fluid inlets 124, 126 of a surge tank 110 so that foam can escape into an air gap above the fluid level.

A need exists for an improved surge tank which is operatively configured to reduce or minimize air bubbles from recirculating through the engine cooling system.

SUMMARY

A surge tank is provided according to the embodiment(s) disclosed herein. The surge tank includes a reservoir wherein the reservoir defines a coolant receiving inlet for coupling to the engine. The reservoir also defines a reservoir outlet. The coolant receiving inlet receives a flow of coolant from the engine. The reservoir outlet is the outlet through which the flow of coolant is returned to the engine. The surge tank further includes a plurality of objects disposed within the coolant reservoir. The plurality of objects are operatively configured to float at an upper surface of the coolant in the reservoir and to dampen the momentum of the coolant flowing from the engine.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of embodiments of the present disclosure will become apparent by reference to the following detailed description and drawings, in which like reference numerals correspond to similar, though perhaps not identical, components. For the sake of brevity, reference numerals or features having a previously described function may or may not be described in connection with other drawings in which they appear.

FIG. 1 is a simplified diagram of one example of a vehicle system incorporating a surge tank.

FIG. 2A is a perspective, partial view of a prior art surge tank.

FIG. 2B is a perspective, partial view of a prior art surge tank where the baffles are shown disposed within the tank.

FIG. 2C is a perspective view of one embodiment of a surge tank of the present disclosure.

FIG. 3 is a perspective view of one embodiment of a surge tank of the present disclosure.

FIG. 4A is a cross-sectional view of an embodiment of a surge tank of the present disclosure.

FIG. 4B is an enlarged view of a perforated object.

FIG. 4C is an enlarged schematic view of the coolant interacting with the perforations in an object where an increased surface area of the fluid is exposed to air (i.e. straining effect for water).

FIG. 4D is an enlarged schematic view of the coolant flowing through a hole in the object.

FIG. 5A is a cross sectional view of a second embodiment of a surge tank of the present disclosure where a baffle maintains the plurality of objects in area of the surge tank.

FIG. 5B is a cross sectional view of the second embodiment of a surge tank when the tank is in an inclined position.

FIG. 5C is a cross sectional view of the second embodiment of a surge tank when the tank is agitated.

FIG. 6 is an enlarged, cross-sectional view of the second embodiment of a surge tank when the incoming flow of coolant is dampened by the plurality of objects.

DETAILED DESCRIPTION

A surge tank 10 of the present disclosure provides improved dampening to an incoming flow of coolant 12. Referring now to FIG. 3, one embodiment of the present disclosure includes a reservoir wherein the reservoir 14 defines a coolant receiving inlet 16 for coupling to the engine. The coolant receiving inlet 16 receives a flow of coolant 12 from the engine (shown as 112 in FIG. 1) and a reservoir outlet 19 through which the flow of coolant 12 is returned to the engine.

The surge tank 10 further includes a plurality of objects 18 disposed within the coolant reservoir 14. The plurality of objects 18 are operatively configured to float at an upper surface 20 of the coolant 22 in the reservoir 14 and to dampen the momentum of the coolant flowing from the engine. The plurality of objects 18 may cover a portion (not shown) of the entire upper surface 20 of the coolant 22 disposed within the reservoir 14 or it may cover the entire upper surface 20 of the coolant 22 disposed within the reservoir 14 as shown in FIG. 3.

The plurality of objects 18 may come in a variety of shapes such as, but not limited to spheres, octagons, squares, rectangles, pyramids, and the like. The plurality of objects 18 are formed from polymeric materials. The plurality of objects 18 (which may be spheres, octagons, squares) may be hollow or solid. It is to be understood that it may be more cost effective and lighter weight to have hollow instead of solid objects 18.

Referring now to FIG. 4A, a cross sectional view of the first embodiment of the present disclosure is shown where the plurality of objects 18 form multiple layers 24, 26, 28 near the surface 20 of the coolant 22 which is disposed within the reservoir 14. It is to be understood that a first layer 24 of the plurality of objects 18 may be disposed below the surface 20 of the coolant 22. A second layer 26 may be disposed at the surface 20 of the coolant 22 and a third layer 28 of objects 18 may be disposed above the surface 20 of the coolant 22 as shown.

Each of the objects 18 may be solid, or perforated or both solid and perforated. Referring to FIGS. 4B and 4C, the perforations 30 in the objects 18 increase the surface area of the fluid 32 which would be exposed to air. The exposure of the surface area of the fluid to air causes a straining effect for the water. It is also to be understood that the flow of coolant 12 may pass through the perforations as well as shown in FIG. 4D.

Referring now to FIG. 5A-5C, another embodiment of a surge tank 10 of the present disclosure is shown. The surge tank 10 includes a reservoir 14 wherein the reservoir 14 defines a coolant receiving inlet 16 which is coupled to an engine (not shown). The coolant receiving inlet 16 receives a flow of coolant 12 from the engine. The surge tank 10 further includes a reservoir outlet 19 through which the flow of coolant 12 is returned to the engine. The surge tank 10 further includes a baffle (or grating) 32 and a plurality of objects 18. The baffle (or grating) 32 may be affixed to the internal surface of the reservoir 14 or may be integral to the reservoir 14. The baffle (or grating) 32 forces the plurality of objects 18 to remain in the upper portion 34 of the surge tank 10 even when the surge tank 10 is inclined or agitated as shown in FIGS. 5B and 5C respectively. Therefore, as fluid flows from the coolant receiving inlet 16, there will always be a plurality of objects 18 to dampen the flow of coolant 12 before or as it comes into contact with the coolant 22 that is disposed within the reservoir 14.

FIG. 5B shows the second embodiment of the present disclosure in an inclined position. As shown, the surface 20 of the coolant remains horizontal. The plurality of objects 18 remains in the upper portion 34 of the reservoir 14 due to the baffle (or grating) 32. FIG. 5C shows the second embodiment of the present disclosure where the reservoir is agitated. Again, the plurality of objects 18 remains in the upper portion 34 of the reservoir 14 due to the baffle (or grating) 32 despite the movement of the reservoir 14 and the flow of coolant 12 will always be dampened under this condition.

As indicated, the plurality of objects 18 are disposed within the coolant reservoir 14 in an upper portion 34 of the surge tank 10 and are operatively configured to float at an upper surface 20 of the coolant 22 in the reservoir 14. The plurality of objects 18 in conjunction with the baffle 32 are operatively configured to dampen the momentum of the flow of coolant 12 from the engine. Accordingly, air in the form of air bubbles is minimized within the coolant due to the dampened momentum in the flow of coolant 12 from the engine and the dispersing of the air bubbles that are in the coolant.

Similar to the first embodiment, it is to be understood that the plurality of objects 18 may be either hollow or solid or semi-sold (perforated) as described above. The plurality of objects 18 may also be formed from a polymeric material or the like.

Each object 18 may have a diameter of about 0.5 inches. However, it is to be understood that the diameter may vary depending on the configuration of the surge tank 10. It is also to be understood that the plurality of objects 18 cover at least a substantial amount of the upper surface 20 of the coolant 22 in the reservoir 14. The entire upper surface 20 of the coolant 22 in the reservoir 14 may be covered by the plurality of objects 18 or a substantial portion of the coolant 22 in the reservoir 14 may be covered.

Referring now to FIG. 6, air bubbles are dispersed due to the plurality of objects. The incoming flow of coolant 12 which enters the reservoir 14 merely needs to be dampened by engaging with the plurality of objects 18. As shown, the air bubbles 36 are dispersed and move up to the surface of the coolant as the air bubbles engage with the plurality of objects 18. A thin liquid film (38 in FIG. 6) forms over and around the objects 18 which makes a shorter travel distance for air bubbles 36 to rise up to be exposed to air and to break up.