SE1451593A1

SE1451593A1 - Cooling system for cooling a combustion engine

Info

Publication number: SE1451593A1
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: 2016-06-20
Also published as: DE112015005236T5; DE112015005236B4; BR112017012519A2; SE540255C2; WO2016099377A1

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).(Fig 1)

Description

Coolinq system for coolinq a combustion enqine and a motor vehicle comprisinq such a coolinq system FIELD OF THE INVENTION AND PRIOR ART The present invention relates to a cooling system according tothe preamble of claim 1 for cooling a combustion engine. Theinvention also relates to a motor vehicle provided with such a cooling system.

A combustion engine of a motor vehicle is cooled by means ofcoolant which is circulated in a cooling circuit of a coolingsystem. A centrifugal pump is normally used for circulating thecoolant in the cooling circuit. The pressure in the cooling circuitis at the lowest at the pump inlet of the centrifugal pump. The lowpressure implies a risk of cavitation at the pump inlet, which may cause damages to the pump. lt is previously known that a swirling motion of the fluid at the PUmPconditions for the fluid entering the pump rotor, which in its turn inlet of a centrifugal pump will give improved flowwill result in improved pump efficiency and a reduced pressuredrop at the pump inlet. The reduced pressure drop will in its turnresult in a reduction of the risk of cavitation at the pump inlet. Aswirling motion of the inlet flow at the pump inlet of a centrifugalpump may for instance be achieved in the manner suggested inUS 6 517 309 B1, inject a part of the outlet flow of the pump where two or more injection nozzles areconfigured to tangentially into fluid flowing axially towards the pump inlet through an inlet conduit. A similar solution is suggested inEPO993 547 B1, where coolant from a bypass conduit of acooling circuit is made to flow tangentially into coolant flowingaxially towards the pump inlet through a coolant conduit from aradiator, 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 andfavourable manner of achieving a swirling motion of the coolantflow 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 objectis 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 ofcoolant 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 circulatingthe coolant in the cooling circuit, the centrifugal pump having apump inlet; and - a swirl chamber provided in the cooling circuit immediately upstream of the pump inlet.

The cooling circuit comprises a first conduit for conveyingcoolant from a coolant outlet of the radiator towards the pumpinlet of the centrifugal pump, and a second conduit, via whichcoolant circulating in the cooling circuit can bypass the radiatoron its way from a coolant outlet of the combustion engine to acoolant inlet of the combustion engine. A downstream end of thefirst conduit and a downstream end of the second conduit aretangentially connected to the swirl chamber from differentdirections, preferably opposite directions, to thereby produce aswirling coolant flow in the swirl chamber and in the pump inlet.Thus, both the coolant flow from the radiator and the coolant flowfrom the bypass conduit, i.e. the above-mentioned secondconduit, will contribute to the generation of a swirling motion ofthe coolant flow at the inlet of the centrifugal pump, and anefficient swirling of the inlet flow at the pump inlet may therebyby achieved also in a situation when there is no or only verylimited coolant flow in the bypass conduit or in the conduit fromthe radiator. Furthermore, said swirling is achieved withouthaving to draw off any pressurized coolant from the outlet flow ofthe centrifugal pump. The solution according to the presentinvention 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 thepresent 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 descriptionof preferred embodiments of the invention cited as examples follows below. ln the drawings: Fig 1 is an outline diagram of a cooling system according toan embodiment of the present invention, Fig 2 is a schematic planar view of a centrifugal pump andan associated swirl chamber included in the coolingsystem of Fig 1, and Fig 3 is a cut according to the line III-III in Fig 2.

DETAILED DESCRIPTION OFINVENTION EMBODIMENTS OF THE A cooling system 1 according to an embodiment of the presentinvention is schematically illustrated in Fig 1. This cooling system1 comprises a cooling circuit 2 for cooling a combustion engine 3by means of a coolant flowing through the cooling circuit,preferably in the form of water possibly with anti-freezingadditives such as for instance glycol. A centrifugal pump 5 isprovided in the cooling circuit 2 in order to circulate the coolantin the cooling circuit. Furthermore, a radiator 6, for instance inthe form of a conventional coolant radiator, is provided in the cooling circuit 2 in order to cool the coolant. ln the illustrated example, the cooling system 1 is used forcooling the combustion engine 3 of a motor vehicle 4. However,the cooling system of the present invention may also be used forcooling 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 8bof the radiator 6 towards a pump inlet 9a of the centrifugal pump - a second conduit 10, via which coolant circulating in the coolingcircuit 2 can bypass the radiator 6 on its way from a coolantoutlet 11b of the combustion engine 3 to a coolant inlet 11a ofthe combustion engine 3; - a third conduit 12 for conveying coolant from the coolant outlet11b of the combustion engine 3 to a coolant inlet 8a of theradiator 6; and - a fourth conduit 13 for conveying coolant from a pump outlet 9bof the centrifugal pump 5 to the coolant inlet 11a of the combustion engine 3.

Said second conduit 10 is configured to allow coolant to bereturned from the coolant outlet 11b of the combustion engine 3to the coolantinlet11a of the combustion engine without passingthrough the radiator 6. Thus, the second conduit 10 constitutes abypass conduit for the coolant. Between the coolant inlet 11a andthe coolant outlet 11b of the combustion engine 3, the coolant iscirculated through coolant ducts (not shown) inside thecombustion engine while absorbing heat from the combustion engine.

A thermostat 15 is provided in the cooling circuit 2 at the junctionpoint between the third conduit 12 and the second conduit 10,wherein an upstream end 16 of the second conduit 10 isconnected to a coolant outlet 17 of the thermostat 15. Dependingon the temperature of the coolant leaving the combustion engine3, the thermostat 15 will combustion engine 3 to the radiator 6 for cooling therein before either direct the coolant from the being returned to the combustion engine 3, or direct the coolantfrom the combustion engine 3 directly back to the combustionengine via the second conduit 10 without passing through the radiator 6.

The coolant flowing through the radiator 6 is cooled by means ofair which is blown towards the radiator when the motor vehicle 4is in motion. The cooling system 1 may also comprise a fan (notshown) for generating an air flow through the radiator 6. This fanmay 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 coolingcircuit 2. An outlet 21 of the expansion tank 20 is connected tothe above-mentioned first conduit 7 via a fifth conduit 22 of thecooling circuit 2. This fifth conduit 22 is connected to the firstconduit 7 at a point located between the radiator 6 and thecentrifugal pump 5. A first inlet 23a of the expansion tank 20 isconnected to the radiator 6 via a first vent conduit 24 in order toallow coolant and air to flow from the radiator 6 and into theexpansion tank 20 via this first vent conduit 24. A second inlet 23b of the expansion tank 20 is connected to cooling ducts in the combustion engine 3 via a second vent conduit 25 in order toallow coolant and air to flow from the combustion engine 3 andinto the expansion tank 20 via this second vent conduit 25.Coolant is conveyed into the expansion tank 20 via the ventconduits 24, 25 and is returned from the expansion tank 20 to thecooling 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 apump rotor 27 rotatably mounted to the pump housing, asi||ustrated in Fig 2. The pump rotor 27 is schematically i||ustratedby broken lines in Fig 2. The pump in|et 9a is concentric with thepump rotor 27 and preferably has a circular cross-sectionalshape. A swirl chamber 28 is provided in the cooling circuit 2immediately upstream of the pump in|et 9a. A downstream end 29of the first conduit 7 and a downstream end 30 of the secondconduit 10 are tangentially connected to the swirl chamber 28from different directions to thereby produce a swirling coolantflow, i.e. a rotary motion of the coolant, in the swirl chamber 28and in the pump in|et 9a, as i||ustrated by the arrows in Fig 3.The coolant is made to rotate in the swirl chamber 28 in adirection corresponding to the rotary direction of the pump rotor27 or in a direction opposite the rotary direction of the pump rotor27.

The coolant entering the swirl chamber 28 from the first conduit 7is directed against a first curved wall section 31 (see Fig 3) in theswirl chamber 28, whereas the coolant entering the swirlchamber 28 from the second conduit 10 is directed against a second curved wall section 32 in the swirl chamber 28. ln the illustrated embodiment, said first and second curved wallsections 31, 32 are located opposite each other on oppositesides of a centre axis 33 of the swirl chamber 28. The position ofthe in|et opening 34 of the pump in|et 9a in relation to the centreaxis 33 of the swirl chamber 28 is illustrated by a broken line in Fig 3. ln the illustrated embodiment, the first conduit 7 has an endsection 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. ln the illustratedembodiment, also the second conduit 10 has an end section 36which extends from the swirl chamber 28 in a direction perpendicularly, or at least essentially perpendicularly, to the centre axis 33 of the swirl chamber. ln the illustrated embodiment, the end sections 35, 36 of the firstand second conduits 7, 10 are offset from each other by an angleof 180° about the centre axis 33 of the swirl chamber 28. Thisoffset angle may however have any desired value in an intervalfrom 90° to 270°. ln the illustrated embodiment, the swirl chamber 28 has a circularcross-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 particularlyintended 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 theembodiments described above. On the contrary, manypossibilities to modifications thereof will be apparent to a personwith 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) bymeans of coolant circulating in the cooling circuit (2); - a radiator (6) provided in the cooling circuit (2) for coolingthe coolant; and - a centrifugal pump (5) provided in the cooling circuit (2) forcirculating the coolant in the cooling circuit, the centrifugalpump (5) having a pump in|et (9a); wherein the cooling circuit (2) comprises a first conduit (7) forconveying coolant from a coolant outlet (8b) of the radiator (6)towards the pump in|et (9a) of the centrifugal pump (5), and asecond conduit (10), via which coolant circulating in thecooling circuit (2) can bypass the radiator (6) on its way froma coolant outlet (11b) of the combustion engine (3) to acoolant in|et (11a) of the combustion engine (3),characterized in that a swirl chamber (28) is provided in thecooling circuit (2) immediately upstream of the pump in|et(9a), wherein a downstream end (29) of the first conduit (7)and a downstream end (30) of the second conduit (10) aretangentia||y connected to the swirl chamber (28) from differentdirections to thereby produce a swirling coolant flow in the swirl chamber (28) and in the pump in|et (9a). A cooling system according to c|aim 1, characterized in thatthe downstream end (29) of the first conduit (7) and the(30) (10)tangentia||y connected to (28) downstream end of the second conduit are the swirl chamber from opposite directions. 6. _ A cooling 11 A cooling system according to claim 1 or 2, characterized inthat the first conduit (7) has an end section (35) whichthe (28) in a perpendicularly, or at least essentially perpendicularly, to the extends from swirl chamber direction centre axis (33) of the swirl chamber (28).

1. -3, characterized in that the second conduit (10) has an end system according to any of claimssection (36) which extends from the swirl chamber (28) in a direction perpendicularly, or at least essentiallyperpendicularly, to the centre axis (33) of the swirl chamber(28). A cooling system according to any of claims 1-4,characterized in: - that the radiator (6) has a coolant inlet (8a) which isconnected 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) isconnected to a coolant outlet (17) of the thermostat (15). A motor vehicle comprising a combustion engine (3),characterized in that the motor vehicle (4) comprises acooling system (1) according to any of claims 1-5 for cooling the combustion engine (3).