WO2004076022A1

WO2004076022A1 - Arrangement for the separation of gas from a fluid

Info

Publication number: WO2004076022A1
Application number: PCT/SE2004/000221
Authority: WO
Inventors: Magnus Hagberg
Original assignee: Scania Cv Ab (Publ)
Priority date: 2003-02-27
Filing date: 2004-02-19
Publication date: 2004-09-10
Also published as: SE0300511L; SE0300511D0; DE112004000363T5; SE524916C2

Abstract

The present invention relates to a device for separating gas from a liquid medium. The device comprises an internal space (18), an inlet aperture (17a) for supplying the medium to the space (18), and a rotatable part (20). The rotatable part (20) comprises means (20b) adapted to using the kinetic energy of the medium supplied to impart a rotation movement to the medium in the space (18). The device is used with advantage for cooling the coolant in a cooling system for a combustion engine.

Description

Arrangement for the separation of gas from a fluid

BACKGROUND TO THE INVENTION, AND STATE OF THE ART

The present invention relates to a device for separating gas from a liquid medium according to the preamble of claim 1.

Cooling systems in vehicles usually comprise an expansion tank arranged above the radiator. One purpose of a conventional expansion tank is to provide an expandable space for the coolant. Further purposes of the expansion tank comprise enabling coolant replenishment and providing the cooling system with ventilation. Providing the cooling system with ventilation entails the expansion tank being situated at a high level in the cooling system. An expansion tank also requires a relatively large volume to cater for coolant expansion. A conventional expansion tank therefore occupies a relatively large space at a location which it is desirable to use for other components of the vehicle.

US 2278 397 refers to a combined liquid pump and a gas separator in a cooling system for a combustion engine. In that case the coolant is led into a cylindrical space via a multiplicity of radially arranged inlet apertures. The space is delineated by a cylindrical wall surface which is connected firmly to the pump. During operation of the pump, the cylindrical wall surface rotates, subjecting the coolant in the space to centrifugal force which urges the coolant towards the cylindrical wall surfaces of the space, while gases, which are considerably lighter than the liquid, gather centrally in the space. The liquid is led out by the pump blades via a radially situated liquid outlet, while the gases ar,e led out via a gas outlet situated centrally in the cylindrical space.

GB 817 944 refers to a device for separating air from coolant. In that case the coolant is led into a space in a lower portion of the device via a spiral path with continuously increasing radius. The shape of the path converts the linear flow direction of the coolant entering the space to a rotation movement. An outlet aperture for the coolant is situated radially in the space. The lighter air which gathers centrally in the space is directed to being led out to the surrounding atmosphere via a centrally arranged air pipe.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a device for separating gas from a medium of the kind mentioned in the introduction, in such a way that gas separation is effected by means of a relatively simple and effective structure.

This object is achieved with the device of the kind mentioned in the introduction which is characterised by the features indicated in the characterising part of claim 1. A pump or the like is usually adapted to effecting the transport of the medium in a pipe system which comprises said device. The medium therefore has at least a certain velocity when it reaches the device. This kinetic energy is then used for driving the rotatable part so that it imparts a rotation movement to the medium present in the space. Such a rotatable part brings about an effective rotation movement of the medium in the space without any need to arrange a separate driving device for the rotatable part. The rotatable part imparts an effective rotation movement to the medium, causing the heavier liquid to be urged towards the walls of the space by centrifugal force, while the considerably lighter gas gathers centrally in the space. A simple and effective way of separating the gas in the medium is thus provided. The centrally gathered gas may be led away via a suitably situated outlet passage.

According to a preferred embodiment of the present invention, said means of the rotatable part comprises a surface which is at an angle to the main direction of flow of the inflowing medium. A suitable configuration of that surface enables at least some of the kinetic energy of the medium to be converted to a rotary movement of the rotatable part when the medium meets said surface. The medium usually has a mainly rectilinear direction of flow when it meets said surface. The rotatable part comprising a surface set at a suitable angle to the rectilinear direction of flow of the medium thus has a rotation movement imparted to it. With advantage, said means comprises at least one blade with such a surface. The rotatable part preferably comprises a suitable number of such blades so that a substantial proportion of the kinetic energy of the medium can be used for driving the rotatable part.

According to a preferred embodiment of the present invention, the rotatable part has running through it at least one passage comprising a layer of material which prevents passage of liquid but allows passage of gas. Such a layer of material allowing only passage of gas makes it easy for gas which gathers centrally in the recess to be carried past the rotatable part. With advantage, the device comprises for the gas which is separated from the medium an outlet passage comprising a layer of material which prevents passage of liquid but allows passage of gas. Here again it is advantageous to arrange a layer of liquid-barring material to prevent liquid being led out via the gas outlet passage. Such a gas outlet passage may have in the space an aperture close to an axis of rotation about which the medium provides said rotation movement. The rotation movement of the medium thus causes the liquid to be urged radially outwards from the axis of rotation by centrifugal force. At the same time, any gas in the medium will gather centrally in the space in the vicinity of the axis of rotation. It is therefore advantageous to arrange the aperture for the gas outlet passage close to the axis of rotation. Said gas outlet passage preferably comprises an overpressure valve. Separated gas in the outlet passage will thus only be led out to the surroundings when a specified positive pressure prevails in the outlet passage.

According to a preferred embodiment of the present invention, the device comprises for liquid separated from gas an outlet which has an aperture situated in a delineating surface of the space at a substantially maximum radial distance from said axis. The rotation movement of the medium in the space therefore causes the heavier liquid to be urged radially outwards. Such a location for the liquid outlet aperture ensures that it will be kept free from gas.

According to another preferred embodiment of the present invention, the space comprises a layer of material which prevents passage of liquid but allows passage of gas and which has an extent in a substantially horizontal plane at the same height as the liquid outlet aperture. Such a layer of material prevents liquid from rising above the level of the outlet line. At the same time any gas which for any reason does not gather centrally in the space will be able to pass through the layer of material and rise upwards to an upper portion of the space. From said upper portion of the space, the gas is enabled to be led into the gas outlet and out from the space. All of the abovementioned layers of material which prevent passage of liquid but allow passage of gas may comprise the material known by the trade name gortex.

According to another preferred embodiment of the present invention, the device forms part of a cooling system of a vehicle. A vehicle's cooling system usually comprises an expansion tank situated at a highest level in the cooling system. The primary purpose of the expansion tank is to provide a space which allows expansion of the coolant. Further purposes of the expansion tank comprise enabling coolant replenishment and providing the cooling system with ventilation. Providing the cooling system with ventilation entails the expansion tank being at a high location. Using a separate ventilation device enables the expansion tank to be of significantly simpler design. In such cases the expansion tank may with advantage take the form of an expansion bellows. An expansion bellows provides a variable volume to accommodate coolant. It therefore need not contain air for filling the space not occupied by the coolant. At the same time, an expansion bellows need not be at a high location in the cooling system and may be situated at substantially any desired location. Such a ventilation device and an expansion bellows in a cooling system result in the freeing of a relatively large space which can be used by other components of the vehicle.

BRIEF DESCRIPTION OF THE DRAWING

A preferred embodiment of the invention is described below by way of example with reference to the attached drawing, in which:

Fig. 1 depicts schematically a cooling system of a vehicle with a ventilation device according to the present invention and Fig. 2 depicts an embodiment of the ventilation device. DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

Fig. 1 depicts a cooling system with a circulating coolant for cooling a combustion engine 1. After being heated by the combustion engine 1, the coolant in the cooling system is led out via a line 2 towards a thermostat 3. If the temperature of the coolant exceeds a set temperature of the thermostat 3, the coolant is led through the thermostat 3 to the radiator 4 in order to be cooled. After passing through the radiator 4, the coolant is led through a line 5 to a radiator liquid pump 6 for continuing transport to the combustion engine 1 via an oil cooler 7. If the temperature of the coolant does not exceed the set temperature of the thermostat 3, the coolant is led via the thermostat and a bypass line back to the engine 1 via the pump 6. A control valve 8 may be used to cause some of the coolant from the engine 1 to be used for heating purposes. When the control valve 8 is open, hot coolant is led via a line 9 to a heat exchanger 10 to provide heating, e.g. for a driver's space in the vehicle. The coolant pump 6 causes the cooled coolant which has passed through the heat exchanger 10 to be led back to the engine 1 via the line 11 and the line 5.

A first ventilation line 12 for the coolant extends from the engine 1 to a ventilation device 13. A second ventilation line 14 for the coolant extends from the radiator 4 to the ventilation device 13 via the first ventilation line 12. The ventilation device 13 is adapted to separating from the coolant any air arising in the cooling system. After being ventilated, the coolant is led via a line 15 to an expansion bellows 16. An expansion bellows 16 is a storage vessel for coolant which has an internal space of variable size for accommodating the coolant. An expansion bellows 16 thus need have no access to air for filling the internal space which is not occupied by the coolant. The expansion bellows 16 thus need not be at such a high location as a rigid expansion vessel. The coolant from the expansion bellows 16 is drawn off to the engine 1 by the pump 6 via the line 5.

Fig. 2 depicts the ventilation device 13 in more detail. The ventilation device 13 comprises a housing 17 which has an internal space 18. Coolant is supplied to a lower inlet aperture 17a of the housing 17 via the line 12. A relatively long and narrow element 19 extends transversely across the inlet aperture 17a. The transverse element 19 comprises a cylindrically shaped portion 19a which protrudes upwards. A rotatable part 20 comprises in a lower end surface a hole 20a with a shape corresponding to that of the upwardly protruding portion 19a. The rotatable part 20 is thus arranged for rotation about the upwardly protruding portion 19a. The coolant flows in a substantially linear manner through the inlet aperture 17a, past the transverse element 19 and into the space 18 radially outwards about the lower portion of the rotatable part 20. The rotatable part 20 comprises a multiplicity of blades 20b provided with surfaces which are at an angle to the substantially linear coolant inflow. When the coolant inflow meets the angled surfaces of the blades 20b, it imparts to the rotatable part 20 a rotation movement in the space 18 round the upwardly protruding portion 19a. The upwardly protruding portion 19a also comprises a suitable connection to the rotatable part 20 so that it is not lifted by the coolant inflow.

The rotatable part 20 comprises a multiplicity of passages 21 which run through it and are provided with a layer of material which prevents passage of liquid but allows passage of air. Any air situated centrally in the space can therefore rise upwards via said passages 21 to a gas outlet passage 22 which has an aperture 23 close to an axis of rotation a of the rotatable part 20. The aperture 23 is defined by a pipe portion broadening downwards which makes it possible to receive air rising upwards from a relatively large area round the axis of rotation a. The gas outlet passage 22 comprises a layer of material 24 which is adapted to preventing passage of liquid but allows passage of gas. This ensures that liquid will not reach an upper space 25 of the gas outlet passage 22. An overpressure valve 26 defines an upper surface of the upper space 25. The overpressure valve comprises a valvepiece 26a and a spring 26b which is adapted to exerting a specified force holding the valvepiece 26b against a valve seat 26c. The overpressure valve thus only opens and lets air out from the upper space 25 to the surroundings when a specified positive pressure prevails in the upper space 25. A tubular liquid-permeable material 27 defines a wall portion of the gas outlet passage 22. The liquid held back by the layer of material 24 in the gas outlet passage 22 is allowed to leave the gas outlet passage 22 via the liquid-permeable material 27. The liquid thus leaving the gas outlet passage 22 enters the upper section 18a of the space 18. The upper section 18a of the space is separated from the other section of the space 18 by a sheetlike layer of material 28. The liquid which trickles through the material 27 runs downwards to the upper side of the sheetlike layer of material 28. One purpose of the sheetlike layer of material 28 is to prevent liquid making its way upwards to the upper section 18a of the space. The sheetlike layer of material 28 has an extent in a plane substantially perpendicular to said axis of rotation a and substantially at the same height as a liquid outlet aperture 17b in the housing. However, the sheetlike layer of material 28 has a slight slope towards the outlet aperture 17b so that the liquid on its upper side runs towards the outlet aperture 17b by force of gravity. The upper part-space 18a is adapted to receiving any air which for any reason is not accommodated in the gas outlet passage 22 via the aperture 23. The upper section 18a of the space is delineated at an upper surface by the layer of material 24 which thus allows passage of air but not of liquid. Air from the upper part-space 18a can thus pass through the layer of material 24 to the upper space 25 of the outlet passage 22. The cooled coolant is adapted to being led out via the outlet aperture 17b to the line 15 for further transport to the expansion bellows 16.

During operation of the cooling system, coolant flows substantially continuously to the ventilation device 13. The coolant flows in the substantially rectilinear manner through the inlet aperture 17a and into the space 18 radially externally about the lower portion 20a of the rotatable part. The coolant thus has a mainly rectilinear direction of flow when it meets the angled surfaces of the blades 20b. The rotatable part 20 thus has a rotary movement imparted to it by the coolant inflow. In this situation a substantial proportion of the kinetic energy of the coolant is converted to a rotary movement of the rotatable part 20. At the same time, the rotatable part 20 causes by means of the blades a rotation of the coolant present in the space substantially round the axis of rotation a. As the coolant is significantly heavier than any air which accumulates in the coolant, said rotation movement results in the coolant being urged radially outwards by centrifugal force towards the walls of the housing 17, while any air will gather centrally in the recess 18. The radially arranged walls of the housing 17 have a slope such that they are at a maximum radial distance from said axis a at the height of the coolant outlet aperture 17b. The rotating coolant in the space 18 will thus rise upwards and be urged out via the outlet aperture 17b by centrifugal force. Any air which gathers centrally in the space 18 in the region round the axis of rotation a tends to rise upwards due to its low density. The air will thus pass through the passages 21 in the rotatable part 20 and be led into the aperture 23 for the gas outlet passage 22. The air flowing upwards in the gas outlet passage 22 passes through the layer of material 24 and gathers in the upper space 25. When a specified positive pressure prevails in the upper space 25, the overpressure valve 26 opens and the air can flow out to the surroundings. The liquid led into the gas outlet 22 is prevented by the liquid-barring layer of material 24 from reaching the upper space 25. Such liquid falls downwards or trickles out via the liquid-permeable tube material 27. From the outside of the liquid-permeable tube material 27, the liquid runs down to the sheetlike layer of material 28. As the sheetlike layer of material 28 has a slight slope downwards towards the outlet aperture 17b, the liquid runs towards the outlet aperture 17b by force of gravity. Any air in the space which for any reason does not pass through the aperture 23 to the gas outlet passage 22 rises upwards and accumulates at a lower surface of the sheetlike material 28. As the sheetlike layer of the material 28 allows passage of air, the air passes through the layer of material 28 and gathers in the part- space 18a. From the part-space 18a the air can pass through the layer of material 24 to the upper space 25, from which it is led out via the overpressure valve 26 to the surroundings when the specified positive pressure prevails in the upper space 25.

The ventilation device described results in reliable operation of a rotatable part 20 for imparting rotation to the coolant so as to achieve effective separation of liquid and gas. This involves the rotatable part 20 being driven by the kinetic energy of the coolant inflow. No special drive mechanism need therefore be arranged for driving the rotatable part 20. An advantage of using a separate ventilation device 13 in a cooling system for a combustion engine 1 instead of a conventional expansion tank with a ventilation function is that the expansion vessel can be of significantly simpler design. The expansion vessel in the form of an expansion bellows 16 is particularly advantageous in that it does not contain air and can therefore be arranged at substantially any desired level in the cooling system. All of the abovementioned layers of material 21, 24, 28 which prevent passage of liquid but allow passage of gas may comprise the material known by the trade name gortex.

The invention is in no way limited to the embodiment described in the drawing but may be varied freely within the scopes of the claims. The device is not limited to being used in a cooling system of a vehicle and may be used in any desired context where gas is to be separated from a liquid.

Claims

1. A device for separating gas from a liquid medium, whereby the device comprises an internal space (18), an inlet aperture (17a) adapted to supplying the liquid medium together with any gas to the space (18), and a rotatable part (20) adapted to imparting a rotation movement to the medium in the space (18), characterised in that the rotatable part (20) comprises means (20b) adapted to using the kinetic energy of the medium supplied in order to impart said rotation movement to the medium in the space (18).

2. A device according to claim 1, characterised in that said means (20b) of the rotatable part comprises a surface which is at an angle to the main direction of flow of the inflow of medium.

3. A device according to claim 2, characterised in that said means comprises at least one blade (20b) which is provided with such a surface.

4. A device according to any one of the foregoing claims, characterised in that the rotatable part (20) has running through it at least one passage (21) provided with a layer of material (21a) which prevents passage of liquid but allows passage of gas.

5. A device according to any one of the foregoing claims, characterised in that the device comprises for gas separated from the medium an outlet passage (22) comprising a layer of material (24) which prevents passage of liquid but allows passage of gas.

6. A device according to any one of the foregoing claims, characterised in that said gas outlet passage (22) has an aperture in the space (18) close to an axis (a) round which the medium imparts said rotation movement.

7. A device according to claim 6, characterised in that said gas outlet passage (22) comprises an overpressure valve (26).

8. A device according to any one of the foregoing claims, characterised in that the device comprises an outlet aperture (17b) for liquid separated from gas, whereby the liquid outlet aperture (17b) is situated in a delineating surface of the space (18) at a substantially maximum radial distance from said axis ( ).

9. A device according to claim 7, characterised in that the space (18) comprises a layer of material (28) which prevents passage of liquid but allows passage of gas, whereby the layer of material (28) has an extent in a substantially horizontal plane at the same height of the coolant outlet aperture (17b).

10. A device according to any one of the foregoing claims, characterised in that the device forms part of a cooling system for a combustion engine (1).