SE540255C2

SE540255C2 - Cooling system for cooling a combustion engine and a motor vehicle comprising such a cooling system

Info

Publication number: SE540255C2
Application number: SE1451593A
Authority: SE
Inventors: Petersson Kim; Petter Johnson
Original assignee: Scania Cv Ab
Priority date: 2014-12-19
Filing date: 2014-12-19
Publication date: 2018-05-15
Also published as: SE1451593A1; BR112017012519A2; WO2016099377A1; DE112015005236T5; DE112015005236B4

Abstract

A cooling system (1) comprising:- a cooling circuit (2) for cooling a combustion engine (3) by means of coolant circulating in the cooling circuit;- a radiator (6) for cooling the coolant;- a centrifugal pump (5) for circulating the coolant in the cooling circuit; and- a swirl chamber (28) provided in the cooling circuit immediately upstream of a pump inlet (9a) of the pump.The cooling circuit comprises a first conduit (7) for conveying coolant from the radiator towards the pump inlet (9a), and a second conduit (10), via which coolant can bypass the radiator. A downstream end (29) of the first conduit and a downstream end (30) of the second conduit are tangentially connected to the swirl chamber (28) from different directions to thereby produce a swirling coolant flow in the swirl chamber and in the pump inlet (9a).

Description

Cooling system for cooling a combustion engine and a motor vehicle comprising such a cooling system FIELD OF THE INVENTION AND PRIOR ART The present invention relates to a cooling system according to the preamble of claim 1 for cooling a combustion engine. The invention also relates to a motor vehicle provided with such a cooling system.

A combustion engine of a motor vehicle is cooled by means of coolant which is circulated in a cooling circuit of a cooling system. A centrifugal pump is normally used for circulating the coolant in the cooling circuit. The pressure in the cooling circuit is at the lowest at the pump inlet of the centrifugal pump. The low pressure implies a risk of cavitation at the pump inlet, which may cause damages to the pump.

It is previously known that a swirling motion of the fluid at the pump inlet of a centrifugal pump will give improved flow conditions for the fluid entering the pump rotor, which in its turn will result in improved pump efficiency and a reduced pressure drop at the pump inlet. The reduced pressure drop will in its turn result in a reduction of the risk of cavitation at the pump inlet. A swirling motion of the inlet flow at the pump inlet of a centrifugal pump may for instance be achieved in the manner suggested in US 6 517 309 B1 , where two or more injection nozzles are configured to inject a part of the outlet flow of the pump tangentially into fluid flowing axially towards the pump inlet through an inlet conduit. A similar solution is suggested in EP 0 993 547 B 1 , where coolant from a bypass conduit of a cooling circuit is made to flow tangentially into coolant flowing axially towards the pump inlet through a coolant conduit from a radiator, to thereby achieve a swirling motion of the coolant flow at the pump inlet.

OBJECT OF THE INVENTION The object of the present invention is to achieve a new and favourable manner of achieving a swirling motion of the coolant flow at the inlet of a centrifugal pump in a cooling system for cooling a combustion engine.

SUMMARY OF THE INVENTION According to the present invention, the above-mentioned object is achieved by a cooling system having the features defined in claim 1 .

The cooling system of the present invention comprises: - a cooling circuit for cooling a combustion engine by means of coolant circulating in the cooling circuit; - a radiator provided in the cooling circuit for cooling the coolant; - a centrifugal pump provided in the cooling circuit for circulating the coolant in the cooling circuit, the centrifugal pump having a pump inlet; and - a swirl chamber provided in the cooling circuit immediately upstream of the pump inlet.

The cooling circuit comprises a first conduit for conveying coolant from a coolant outlet of the radiator towards the pump inlet of the centrifugal pump, and a second conduit, via which coolant circulating in the cooling circuit can bypass the radiator on its way from a coolant outlet of the combustion engine to a coolant inlet of the combustion engine. A downstream end of the first conduit and a downstream end of the second conduit are tangentially connected to the swirl chamber from different directions, preferably opposite directions, to thereby produce a swirling coolant flow in the swirl chamber and in the pump inlet. Thus, both the coolant flow from the radiator and the coolant flow from the bypass conduit, i.e. the above-mentioned second conduit, will contribute to the generation of a swirling motion of the coolant flow at the inlet of the centrifugal pump, and an efficient swirling of the inlet flow at the pump inlet may thereby by achieved also in a situation when there is no or only very limited coolant flow in the bypass conduit or in the conduit from the radiator. Furthermore, said swirling is achieved without having to draw off any pressurized coolant from the outlet flow of the centrifugal pump. The solution according to the present invention may be implemented in a very space-saving manner, which is of advantage in a motor vehicle where the available space in the engine compartment is often very limited.

Further advantageous features of the cooling system of the present invention will appear from the following description and the dependent claims.

The invention also relates to a motor vehicle having the features defined in claim 6.

BRIEF DESCRIPTION OF THE DRAWINGS With reference to the appended drawings, a specific description of preferred embodiments of the invention cited as examples follows below. In the drawings: Fig 1 is an outline diagram of a cooling system according to an embodiment of the present invention, Fig 2 is a schematic planar view of a centrifugal pump and an associated swirl chamber included in the cooling system of Fig 1 , and Fig 3 is a cut according to the line III-III in Fig 2.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION A cooling system 1 according to an embodiment of the present invention is schematically illustrated in Fig 1. This cooling system 1 comprises a cooling circuit 2 for cooling a combustion engine 3 by means of a coolant flowing through the cooling circuit, preferably in the form of water possibly with anti-freezing additives such as for instance glycol. A centrifugal pump 5 is provided in the cooling circuit 2 in order to circulate the coolant in the cooling circuit. Furthermore, a radiator 6, for instance in the form of a conventional coolant radiator, is provided in the cooling circuit 2 in order to cool the coolant.

In the illustrated example, the cooling system 1 is used for cooling the combustion engine 3 of a motor vehicle 4. However, the cooling system of the present invention may also be used for cooling an industrial combustion engine or a marine combustion engine.

The cooling circuit 2 comprises: - a first conduit 7 for conveying coolant from a coolant outlet 8b of the radiator 6 towards a pump inlet 9a of the centrifugal pump 5; - a second conduit 10, via which coolant circulating in the cooling circuit 2 can bypass the radiator 6 on its way from a coolant outlet 11 b of the combustion engine 3 to a coolant inlet 11a of the combustion engine 3; - a third conduit 12 for conveying coolant from the coolant outlet 11 b of the combustion engine 3 to a coolant inlet 8a of the radiator 6; and - a fourth conduit 13 for conveying coolant from a pump outlet 9b of the centrifugal pump 5 to the coolant inlet 11 a of the combustion engine 3.

Said second conduit 10 is configured to allow coolant to be returned from the coolant outlet 11 b of the combustion engine 3 to the coolant inlet 11 a of the combustion engine without passing through the radiator 6. Thus, the second conduit 10 constitutes a bypass conduit for the coolant. Between the coolant inlet 1 1a and the coolant outlet 11 b of the combustion engine 3, the coolant is circulated through coolant ducts (not shown) inside the combustion engine while absorbing heat from the combustion engine.

A thermostat 15 is provided in the cooling circuit 2 at the junction point between the third conduit 12 and the second conduit 10, wherein an upstream end 16 of the second conduit 10 is connected to a coolant outlet 17 of the thermostat 15. Depending on the temperature of the coolant leaving the combustion engine 3, the thermostat 15 will either direct the coolant from the combustion engine 3 to the radiator 6 for cooling therein before being returned to the combustion engine 3, or direct the coolant from the combustion engine 3 directly back to the combustion engine via the second conduit 10 without passing through the radiator 6.

The coolant flowing through the radiator 6 is cooled by means of air which is blown towards the radiator when the motor vehicle 4 is in motion. The cooling system 1 may also comprise a fan (not shown) for generating an air flow through the radiator 6. This fan may be connected to the combustion engine 3 in order to be driven by the combustion engine.

Furthermore, an expansion tank 20 is provided in the cooling circuit 2. An outlet 21 of the expansion tank 20 is connected to the above-mentioned first conduit 7 via a fifth conduit 22 of the cooling circuit 2. This fifth conduit 22 is connected to the first conduit 7 at a point located between the radiator 6 and the centrifugal pump 5. A first inlet 23a of the expansion tank 20 is connected to the radiator 6 via a first vent conduit 24 in order to allow coolant and air to flow from the radiator 6 and into the expansion tank 20 via this first vent conduit 24. A second inlet combustion engine 3 via a second vent conduit 25 in order to allow coolant and air to flow from the combustion engine 3 and into the expansion tank 20 via this second vent conduit 25. Coolant is conveyed into the expansion tank 20 via the vent conduits 24, 25 and is returned from the expansion tank 20 to the cooling circuit 2 via the above-mentioned fifth conduit 22 after deaeration in the expansion tank.

The centrifugal pump 5 comprises a pump housing 26 and a pump rotor 27 rotatably mounted to the pump housing, as illustrated in Fig 2. The pump rotor 27 is schematically illustrated by broken lines in Fig 2. The pump inlet 9a is concentric with the pump rotor 27 and preferably has a circular cross-sectional shape. A swirl chamber 28 is provided in the cooling circuit 2 immediately upstream of the pump inlet 9a. A downstream end 29 of the first conduit 7 and a downstream end 30 of the second conduit 10 are tangentially connected to the swirl chamber 28 from different directions to thereby produce a swirling coolant flow, i.e. a rotary motion of the coolant, in the swirl chamber 28 and in the pump inlet 9a, as illustrated by the arrows in Fig 3. The coolant is made to rotate in the swirl chamber 28 in a direction corresponding to the rotary direction of the pump rotor 27 or in a direction opposite the rotary direction of the pump rotor 27.

The coolant entering the swirl chamber 28 from the first conduit 7 is directed against a first curved wall section 31 (see Fig 3) in the swirl chamber 28, whereas the coolant entering the swirl chamber 28 from the second conduit 10 is directed against a second curved wall section 32 in the swirl chamber 28. In the illustrated embodiment, said first and second curved wall sections 31 , 32 are located opposite each other on opposite sides of a centre axis 33 of the swirl chamber 28. The position of the inlet opening 34 of the pump inlet 9a in relation to the centre axis 33 of the swirl chamber 28 is illustrated by a broken line in Fig 3.

In the illustrated embodiment, the first conduit 7 has an end section 35 which extends from the swirl chamber 28 in a direction perpendicularly, or at least essentially perpendicularly, to the centre axis 33 of the swirl chamber. In the illustrated embodiment, also the second conduit 10 has an end section 36 which extends from the swirl chamber 28 in a direction perpendicularly, or at least essentially perpendicularly, to the centre axis 33 of the swirl chamber.

In the illustrated embodiment, the end sections 35, 36 of the first and second conduits 7, 10 are offset from each other by an angle of 180° about the centre axis 33 of the swirl chamber 28. This offset angle may however have any desired value in an interval from 90° to 270°.

In the illustrated embodiment, the swirl chamber 28 has a circular cross-sectional shape. However, the swirl chamber 28 may as an alternative have an oval cross-sectional shape.

The cooling system according to the invention is particularly intended for use in a heavy motor vehicle, such as for instance a bus, a tractor truck or a lorry.

The invention is of course not in any way restricted to the embodiments described above. On the contrary, many possibilities to modifications thereof will be apparent to a person with ordinary skill in the art without departing from the basic idea of the invention such as defined in the appended claims.

Claims

1. A cooling system comprising: - a cooling circuit (2) for cooling a combustion engine (3) by means of coolant circulating in the cooling circuit (2); - a radiator (6) provided in the cooling circuit (2) for cooling the coolant; and - a centrifugal pump (5) provided in the cooling circuit (2) for circulating the coolant in the cooling circuit, the centrifugal pump (5) having a pump inlet (9a); wherein the cooling circuit (2) comprises a first conduit (7) for conveying coolant from a coolant outlet (8b) of the radiator (6) towards the pump inlet (9a) of the centrifugal pump (5), and a second conduit (10), via which coolant circulating in the cooling circuit (2) can bypass the radiator (6) on its way from a coolant outlet (11 b) of the combustion engine (3) to a coolant inlet (1 1a) of the combustion engine (3), characterized in that a swirl chamber (28) is provided in the cooling circuit (2) immediately upstream of the pump inlet (9a), wherein a downstream end (29) of the first conduit (7) and a downstream end (30) of the second conduit (10) are tangentially connected to the swirl chamber (28) from different directions to thereby produce a swirling coolant flow in the swirl chamber (28) and in the pump inlet (9a).

2. A cooling system according to claim 1 , characterized in that the downstream end (29) of the first conduit (7) and the downstream end (30) of the second conduit (10) are tangentially connected to the swirl chamber (28) from opposite directions.

3. A cooling system according to claim 1 or 2, characterized in that the first conduit (7) has an end section (35) which extends from the swirl chamber (28) in a direction perpendicularly, or at least essentially perpendicularly, to the centre axis (33) of the swirl chamber (28).

4. A cooling system according to any of claims 1-3, characterized in that the second conduit (10) has an end section (36) which extends from the swirl chamber (28) in a direction perpendicularly, or at least essentially perpendicularly, to the centre axis (33) of the swirl chamber (28).

5. A cooling system according to any of claims 1-4, characterized in: - that the radiator (6) has a coolant inlet (8a) which is connected to a coolant outlet (11b) of the combustion engine (3) via a third conduit (12) of the cooling circuit (2); - that the cooling system (1 ) comprises a thermostat (15) provided in the third conduit (12); and - that an upstream end (16) of the second conduit (10) is connected to a coolant outlet (17) of the thermostat (15).

6. A motor vehicle comprising a combustion engine (3), characterized in that the motor vehicle (4) comprises a cooling system (1 ) according to any of claims 1-5 for cooling the combustion engine (3).