SE541332C2

SE541332C2 - Cyclone separator and Related Devices

Info

Publication number: SE541332C2
Application number: SE1751408A
Authority: SE
Inventors: Jonatan Bergström
Original assignee: Scania Cv Ab
Priority date: 2017-11-15
Filing date: 2017-11-15
Publication date: 2019-07-09
Also published as: DE102018008548A1; DE102018008548B4; SE1751408A1

Abstract

A cyclone separator (1) is disclosed configured to separate particles from a flow of fluid. The cyclone separator (1) comprises a housing (5) comprising an inflow opening (7) and an outflow opening (9), and a rotor (10). The rotor (10) is rotationally arranged around an axis (11) and comprises at least one guide blade (13) provided with a pitch angle (a1) configured to provide a cyclone around the axis (11), and configured to provide rotation of the rotor (10), when fluid is flowing from the inflow opening (7) towards the outflow opening (9). The cyclone separator (1) further comprises a particle collecting space (15) and a particle evacuation unit (19) configured to be driven by the rotation of the rotor (10). The present disclosure further relates to an air intake arrangement (33), a combustion engine (35), and a vehicle (37).

Description

Cyclone separator and Related Devices TECHNICAL FIELD The present invention relates to a cyclone separator configured to separate particles from a flow of fluid. The present invention further relates to an air intake arrangement for a combustion engine, wherein the air intake arrangement comprises a cyclone separator. Further, the present invention relates to a combustion engine and a vehicle.

BACKGROUND A cyclone separator is a device capable of separating particulates from a flow of fluid, i.e. a flow of air, gas and/or liquid, without the use of filter elements, through cyclone separation. Rotational effects and gravity are used to separate mixtures of solids and fluids. A cyclone separator can also be used to separate droplets of liquid from a gaseous stream.

Cyclone separators are for example used in air intake arrangements for combustion engines. In such applications, the cyclone separator is usually arranged to separate particles from incoming air before the air is led to a conventional air filter comprising a filter element. Such a filter element comprises a filter media through which the air is ducted. The filter media comprises a semi-permeable material through which air can pass and in which particles over a certain size are trapped. The filter media causes a flow resistance which causes a pressure drop over the filter element. The flow resistance and the pressure drop over the filter element increases when particles are trapped in the filter media. Thereby, after a certain operational time, the filter element must be replaced.

In most applications, including when arranged in an air intake arrangement of a combustion engine, it is wanted to obtain a low pressure drop over a cyclone separator. In cases where a cyclone separator is arranged in an air intake arrangement of a combustion engine, a low pressure drop is wanted since a high pressure drop in the air intake of the combustion engine may reduce the fuel efficiency and the performance of the engine. A pressure drop over a cyclone separator is partially caused by the fact that the cyclone separator works with the principle of separation through rotational effects. That is, fluid is usually flowing straight into the cyclone separator. In the cyclone separator, the straight flow is transformed into a cyclone, which causes a pressure drop over the cyclone.

Since a cyclone separator works with the principle of separation through rotational effects, the separation efficiency of the cyclone separator depends on the angular velocity of the cyclone. However, a high angular velocity of the cyclone causes a high pressure drop over the cyclone separator. Conversely, a low angular velocity of the cyclone causes a low separation efficiency of the cyclone separator.

A further problem associated with cyclone separators is the evacuation of separated particles. Commonly, the problem is handled by evacuating the separated particles to a closed container, evacuating the separated particles through a check valve, or using an ejector for evacuating the separated particles. All these solutions are associated with problems. For example, a closed container needs to be emptied periodically, check valves can get clogged, and an ejector needs to be either fan powered or connected to an exhaust pipe via ducts.

In addition, generally, today’s consumer market requires high quality products that comprise different features and functions while the products have conditions for being manufactured, assembled and mounted in a cost-efficient manner.

SUMMARY It is an object of the present invention to overcome, or at least alleviate, at least some of the above-mentioned problems and drawbacks.

According to a first aspect of the invention, the object is achieved by a cyclone separator configured to separate particles from a flow of fluid. The cyclone separator comprises a housing comprising an inflow opening and an outflow opening, and a rotor arranged inside the housing. The rotor is rotationally arranged around an axis and comprises at least one guide blade provided with a pitch angle configured to provide a cyclone around the axis, and configured to provide rotation of the rotor, when fluid is flowing from the inflow opening towards the outflow opening. The cyclone separator further comprises a particle collecting space and an evacuation unit configured to perform a forced evacuation of particles from the particle collecting space. The evacuation unit is configured to be driven by the rotation of the rotor.

Thereby, a cyclone separator is provided with improved particle evacuation capabilities. Further, since the evacuation unit is configured to be driven by the rotation of the rotor, the evacuation of particles from the particle collecting space is performed in an energy efficient manner. Still further, a cyclone separator is provided circumventing the need for a complicated arrangement of ducts connecting the particle collecting space to an ejector in an exhaust pipe.

Still further, since the evacuation unit is configured to be driven by the rotation of the rotor, and since the at least one guide blade is provided with a pitch angle configured to provide a cyclone around the axis, and configured to provide rotation of the rotor, a cyclone separator is provided in which the angular velocity of the cyclone is more consistent at varying flow rates of fluid flowing from the inflow opening towards the outflow opening. That is, since the evacuation unit is configured to be driven by the rotation of the rotor, it is ensured that the rotation of the rotor is counteracted, i.e. braked, so that the at least one guide blade can provide a cyclone around the axis, and so that the angular velocity of the cyclone is more consistent at varying flow rates of fluid flowing from the inflow opening towards the outflow opening.

As a result thereof, a cyclone separator is provided having a more consistent separation efficiency and a more consistent pressure drop over the cyclone separator at varying flow rates of fluid flowing from the inflow opening towards the outflow opening. This because when the flow rate is low, the rotor will rotate at a low rotational velocity in an opposite rotational direction than the rotational direction of the cyclone. When the flow rate is higher, the rotor will rotate at a higher rotational velocity in the opposite rotational direction than the rotational direction of the cyclone. Due to the higher rotational velocity of the rotor at high flow rates, the angular velocity of the cyclone will be lower than would be the case otherwise. As a result, the pressure drop over the cyclone separator is reduced at high flow rates of fluid flowing from the inflow opening towards the outflow opening. Conversely, when the flow rate is lower, the rotor will rotate at a lower rotational velocity in the opposite rotational direction than the rotational direction of the cyclone which causes a higher angular velocity of the cyclone, than would be the case at the higher rotational velocity of the rotor. Thereby, the separation efficiency of the cyclone separator is increased at lower flow rates.

Accordingly, a cyclone separator is provided capable of automatically adapting the separation efficiency and the pressure drop in dependence of the flow rate of fluid flowing from the inflow opening towards the outflow opening. Due to the adaptation of the separation efficiency and the pressure drop, a more consistent separation efficiency, as well as a more consistent pressure drop, is obtained at different flow rates of fluid flowing from the inflow opening towards the outflow opening. Further, the adaptation of the separation efficiency and the pressure drop is performed without having to use control arrangements, motors, or the like, which would have added manufacturing costs to the cyclone separator. Thus, a cyclone separator capable of adapting the separation efficiency and the pressure drop, is provided which can be manufactured in a cost-efficient manner.

Accordingly, a cyclone separator is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

Optionally, the evacuation unit is mechanically connected to the rotor. Thereby, the evacuation unit can be driven by the rotation of the rotor in a simple and efficient manner. Further, it can be ensured that the rotation of the rotor is counteracted, i.e. braked, in a manner such that the rotational velocity of the cyclone is more consistent at varying flow rates of fluid flowing from the inflow opening towards the outflow opening.

Optionally, the cyclone separator comprises a shaft, and wherein the evacuation unit is mechanically connected to the rotor via the shaft. Thereby, the evacuation unit can be driven by the rotation of the rotor in a simple and efficient manner.

Optionally, the evacuation unit comprises an evacuation rotor provided with at least one evacuation blade. Thereby, a simple and efficient evacuation unit is provided.

Optionally, the evacuation rotor is rotationally arranged around a second axis, and wherein the at least one evacuation blade extends radially with respect to the second axis. Thereby, a simple and efficient evacuation unit is provided.

Optionally, the outflow opening comprises a tube extending into the housing, wherein the particle collecting space is arranged between an inner wall of the housing and an outer wall of the tube. Thereby, a cyclone separator is provided capable of separating particles in a simple and efficient manner.

Optionally, the rotor further comprises at least one second blade having a pitch angle configured to counteract the rotation of the rotor when fluid is flowing from the inflow opening towards the outflow opening. Thereby, the rotational velocity of the rotor is further regulated since also the at least one second blade counteracts the rotation of the rotor. The amount by which the at least one second blade counteracts the rotation of the rotor is given by the rotational velocity of the rotor and the flow rate of fluid flowing from the inflow opening towards the outflow opening. Thereby, it is further ensured that the rotation of the rotor is counteracted, i.e. braked, so that the at least one guide blade can provide a cyclone around the axis, and so that the angular velocity of the cyclone is still more consistent at varying flow rates of fluid flowing from the inflow opening towards the outflow opening. In addition, since the at least one second blade has a pitch angle configured to counteract the rotation of the rotor, the rotational energy of the rotor can be partially returned to the fluid flowing from the inflow opening towards the outflow opening. Thereby, the pressure drop over the cyclone separator can be reduced. Further, a straighter flow of fluid through the outflow opening can be provided which also can reduce the pressure drop in a duct connected to the outflow opening.

Optionally, the at least one guide blade and the at least one second blade are arranged at a distance from each other along the axis. Thereby, the at least one second blade can counteract the rotation of the rotor without disturbing the formation of a cyclone by the at least one guide blade. As a result, the separation efficiency is improved, and the pressure drop over the cyclone separator is reduced.

Optionally, the at least one guide blade is arranged closer to the inflow opening than the at least one second blade. Thereby, the cyclone can flow a distance in the housing without being disturbed by the at least one second blade. As a result, the separation efficiency is improved, and the pressure drop over the cyclone separator is reduced.

Optionally, the at least one second blade is arranged in the tube. Thereby, a particle collecting space can be obtained between an outer surface of the tube and an inner surface of the housing. Since the at least one second blade is arranged in the tube, the at least one second blade will not disturb the cyclone and will not disturb the collection of particles in the particle collecting space. As a result thereof, the separation efficiency is improved. Further, since the at least one second blade is arranged in the tube, the rotational velocity of the rotor is regulated without disturbing the cyclone, and the rotational energy of the rotor can be partially returned to the fluid without disturbing the cyclone. In addition, and an even straighter flow of fluid through the outflow opening can be provided. As a result thereof, the separation efficiency is further improved and the pressure drop over the cyclone separator is further reduced.

Optionally, the at least one guide blade is provided with a greater surface area in a direction of the axis than the at least one second blade. Thereby, the formation of a cyclone around the axis can be further ensured. Further, it is in a simple manner ensured that outer portions of the cyclone, which comprises a higher concentration of particles than inner portions of the cyclone, is not disturbed by the at least one second blade. As a result, the separation efficiency can be improved and the pressure drop over the cyclone separator can be reduced.

Optionally, the pitch angle of the at least one second blade is configured to accelerate the flow of fluid past the at least one second blade upon rotation of the rotor. Thereby, it is ensured that the rotational energy of the rotor is at least partially returned to the fluid and that a straighter flow of fluid through the outflow opening is provided. As a result, the pressure drop over the cyclone separator is further reduced.

According to a second aspect of the invention, the object is achieved by an air intake arrangement for a combustion engine, wherein the air intake arrangement is configured to duct ambient air to the combustion engine, and wherein the air intake arrangement comprises a cyclone separator according to some embodiments. The flow rate of air ducted to a combustion engine varies to a great extent. That is, during idling, the flow rate is low and during high load situations, the flow rate is high. Since the air intake arrangement comprises a cyclone separator according to some embodiments, an air intake arrangement is provided capable of adapting the separation efficiency and the pressure drop in dependence of the flow rate of ambient air ducted to the engine. Accordingly, an air intake arrangement is provided having a more consistent separation efficiency and a more consistent pressure drop at different flow rates of air ducted to the combustion engine. Thus, an air intake arrangement is provided with an improved separation efficiency at low load situations of the engine and potentially a lower pressure drop over the air intake arrangement at high load situations of the combustion engine. Further, since the air intake arrangement is provided with an improved separation efficiency at low load situations of the engine, the dust accumulation in a filter element of the air intake arrangement can be reduced. Further, the life time of the filter element can be increased, i.e. the operational time available before the filter element must be replaced can be increased. Still further, the demands on the filter element can be reduced meaning that a low-price filter element, and/or a filter having a low pressure drop, can be used. Still further, droplets of liquids, such as water, can be separated from the air in a more efficient manner which may enhance the performance of the filter element and prolong the life time thereof.

Still further, an air intake arrangement is provided with improved particle evacuation capabilities. Further, since the evacuation unit of the air intake arrangement is configured to be driven by the rotation of the rotor, the evacuation of particles from the particle collecting space is performed in an energy efficient manner. Still further, an air intake arrangement is provided circumventing the need for a complicated arrangement of ducts connecting the particle collecting space to an ejector in an exhaust pipe.

Accordingly, an air intake arrangement is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

According to a third aspect of the invention, the object is achieved by a combustion engine comprising the air intake arrangement according to some embodiments. The flow rate of air ducted to a combustion engine varies to a great extent. That is, during idling the flow rate is low and during high load situations the flow rate is high. Since the combustion engine comprises an air intake arrangement provided with a potentially lower pressure drop over the air intake arrangement at high load situations of the engine, the efficiency of the engine at high load situations can be improved. Further, since the air intake arrangement is provided with an improved separation efficiency at low load situations of the engine, the dust accumulation in a filter element of the air intake arrangement of the engine can be reduced. Further, the life time of the filter element can be increased, i.e. the operational time available before the filter element must be replaced can be increased. Still further, the demands on the filter element can be reduced meaning that a low-price filter element, and/or a filter having a low pressure drop, can be used. Still further, droplets of liquids, such as water, can be separated from the air in a more efficient manner which may enhance the performance of the filter element and prolong the life time thereof.

Still further, a combustion engine is provided with an air intake arrangement having improved particle evacuation capabilities. Further, since the evacuation unit is configured to be driven by the rotation of the rotor, the evacuation of particles from the particle collecting space is performed in an energy efficient manner. Still further, a combustion engine is provided having an air intake arrangement which circumvents the need for a complicated arrangement of ducts connecting the particle collecting space to an ejector in an exhaust pipe of the combustion engine.

Accordingly, a combustion engine is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

According to a fourth aspect of the invention, the object is achieved by a vehicle comprising a combustion engine according to some embodiments. Since the vehicle comprises a combustion engine according to some embodiments, a vehicle is provided overcoming, or at least alleviating, at least some of the above-mentioned problems and drawbacks. As a result, the above-mentioned object is achieved.

Further features of, and advantages with, the present invention will become apparent when studying the appended claims and the following detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS Various aspects of the invention, including its particular features and advantages, will be readily understood from the example embodiments discussed in the following detailed description and the accompanying drawings, in which: Fig. 1 illustrates a cyclone separator, according to some embodiments, Fig. 2 illustrates a combustion engine comprising an air intake arrangement, according to some embodiments, and Fig. 3 illustrates a vehicle comprising the combustion engine illustrated in Fig. 2.

DETAILED DESCRIPTION Aspects of the present invention will now be described more fully. Like numbers refer to like elements throughout. Well-known functions or constructions will not necessarily be described in detail for brevity and/or clarity.

Fig- 1 illustrates a cyclone separator 1, according to some embodiments. The cyclone separator 1 is configured to separate particles from a flow of fluid. The cyclone separator 1 comprises a housing 5 comprising an inflow opening 7 and an outflow opening 9. The inflow opening 7 and the outflow opening 9 are spaced apart along an axis 11. The cyclone separator 1 comprises a rotor 10 arranged inside the housing 5 between the inflow opening 7 and the outflow opening 9. The rotor 10 is rotationally arranged around the axis 11 and comprises at least one guide blade 13 extending radially with respect to the axis 11 .

According to the illustrated embodiments, the rotor 10 is coaxially arranged with respect to the axis 11. In Fig. 1, only two guide blades 13 are indicated with the reference sign “13” for the reason of brevity and clarity. The cyclone separator 1 according to the illustrated embodiments comprises seven guide blades 13, of which only five are visible. The cyclone separator 1 may comprise another number of guide blades 13 than seven, for example a number within the range of 1 - 6, or 8 - 20, or the like. Accordingly, the cyclone separator 1 may comprise one guide blade 13. However, for the reason of brevity and clarity, the guide blade 13 according to such embodiments, is below referred to as “the guide blades 13”.

The guide blades 13 are provided with a pitch angle a1 configured to provide a cyclone around the axis 11, and configured to provide rotation of the rotor 10, when fluid is flowing from the inflow opening 7 towards the outflow opening 9. Due to the cyclone around the axis 11, particles in the fluid that are heavier than the surrounding fluid are forced towards an inner wall 5.1 of the housing 5 by centrifugal force. The cyclone separator 1 comprises a tube 28 coaxially arranged to the axis 11 . The tube 28 extends into the housing 5 from the outflow opening 9. An inside 28.1 of the tube 28 is connected to the outflow opening 9 and is configured to duct fluid from an inside volume of the housing 5 to the outflow opening 9. An outside surface 28.2 of the tube 28 forms a partition wall which together with the inner wall 5.1 of the housing 5 forms a particle collecting space 15. Thus, according to the illustrated embodiments, the particle collecting space 15 is arranged between the outside surface 28.2 of the tube 28 and the inner wall 5.1 of the housing 5.

During operation of the cyclone separator 1, fluid is flowing from the inflow opening 7 onto the guide blades 13. Due to the pitch angle a1 of the guide blades 13, a cyclone of fluid is formed around the axis 11 . Due to the centrifugal force, particles in the fluid are forced towards the inner wall 5.1 of the housing 5. As a result thereof, fluid at the centre of the cyclone will contain less particles than fluid at outer portions of the cyclone. Accordingly, fluid that contains a lower amount of particles is ducted to the outflow opening 9, via the inside 28.1 of the tube 28, and fluid that contains a higher amount of particles is led to the particle collecting space 15. In Fig. 1 the rotational direction d1 of the cyclone is indicated with the arrow d1, the rotational direction d2 of the rotor 10 is indicated with the arrow d2, and the flow direction d of the flow of fluid flowing from the inflow opening 7 towards the outflow opening 9 is indicated with the arrow d. The rotational direction d1 of the cyclone around the axis 11 is herein sometimes referred to as a first rotational direction d1. The rotational direction d2 opposite to the rotational direction d1 of the cyclone around the axis 11 is herein sometimes referred to as the second rotational direction d2.

The cyclone separator 1 further comprises an evacuation unit 19 configured to perform a forced evacuation of particles from the particle collecting space 15 through a particle outflow opening 17. The evacuation unit 19 is configured to be driven by the rotation of the rotor 10.

According to the illustrated embodiments, the cyclone separator 1 comprises a shaft 21 and a belt and pulley arrangement 22, and wherein the evacuation unit 19 is mechanically connected to the rotor 10, via the shaft 21 and belt and pulley arrangement 22. Thus, according to the illustrated embodiments, the evacuation unit 19 is configured to be driven by the rotation of the rotor 10, via the shaft 21 and belt and pulley arrangement 22. As an alternative to, or in addition to, the shaft 21 and the belt and pulley arrangement 22, the cyclone separator 1 may comprise another type of power transmitting arrangement such as gears, chains, gearboxes, and/or an electrical connection, being configured to transfer energy derived from the rotation of the rotor 10 to the evacuation unit 19.

According to the illustrated embodiments, the evacuation unit 19 comprises an evacuation rotor 23 provided with at least one evacuation blade 25 and an evacuation unit chamber 26. The evacuation rotor 23 is rotationally arranged in the evacuation unit chamber 26 around a second axis 27. The at least one evacuation blade 25 extends radially with respect to the second axis 27. The evacuation unit chamber 26 is arranged adjacent to the particle collecting space 15, and is fluidically connected to the particle collecting space 15 via an opening 16. The evacuation unit chamber 26 comprises the particle outflow opening 17. The particle outflow opening 17 may for example be connected to a dust container or the environment outside of the cyclone separator 1 .

During operation of the cyclone separator 1, the rotation of the rotor 10 is transferred to the evacuation unit 19. As a result thereof, the evacuation unit 19 performs a forced evacuation of particles from the particle collecting space 15 through the opening 16 into the evacuation unit chamber 26 and out through the particle outflow opening 17.

Since the evacuation unit 19 is configured to be driven by the rotation of the rotor 10, the evacuation of particles from the particle collecting space 15 is performed in an energy efficient manner, and a cyclone separator 1 is provided with improved particle evacuation capabilities. Further, since the evacuation unit is configured to be driven by the rotation of the rotor 10, it is ensured that the rotation of the rotor 10 is counteracted, i.e. braked, so that the at least one guide blade 13 can provide a cyclone around the axis 11, and so that the angular velocity of the cyclone is more consistent at varying flow rates of fluid flowing from the inflow opening 7 towards the outflow opening 9.

The pitch angles a1 of the guide blades 13 are configured to provide rotation of the rotor 10 in the second rotational direction d2, i.e. in a rotational direction d2 opposite to the rotational direction d1 of the cyclone around the axis 11, when fluid is flowing from the inflow opening 7 towards the outflow opening 9. According to the illustrated embodiments, the rotor 10 is rotationally arranged to the housing 5 via arms 30 arranged between the housing 5 and the rotor 10. The rotation of the rotor 10 in the second rotational direction d2 affects the rotational velocity of the cyclone in the first rotational direction d1 in the sense that the rotation of the of the rotor 10 in the second rotational direction d2 lowers the rotational velocity of the cyclone in the first rotational direction d1 . Thus, due to rotation of the rotor 10 in the second rotational direction d2, the rotational velocity of the cyclone in the first rotational direction d1 will be lower than would be the case otherwise. Accordingly, at a given flow rate of fluid flowing from the inflow opening 7 towards the outflow opening 9, the rotational velocity of the cyclone in the first rotational direction d1 is lower when the rotor 10 rotates at a higher rotational velocity in the second rotational direction d2, than when the rotor 10 rotates at a lower rotational velocity in the second rotational direction d2.

According to the illustrated embodiments, the rotor 10 further comprises a set of second blades 29 each having a pitch angle a2 configured to counteract the rotation of the rotor 10 when fluid is flowing from the inflow opening 7 towards the outflow opening 9. In Fig. 1, only two second blades 29 are indicated with the reference sign “29” for the reason of brevity and clarity. The cyclone separator 1 according to the illustrated embodiments comprises eight second blades 29, of which only seven are visible. The cyclone separator 1 may comprise another number of second blades 29 than eight, for example a number within the range of 1 - 7, or 9 - 20, or the like. Thus, according to some embodiments, the cyclone separator 1 may comprise one second blade 15. However, for the reason of brevity and clarity, the second blade 29 according to such embodiments, is below referred to as “the second blades 29”.

The rotational velocity of the rotor 10 is regulated by the second blades 29 counteracting the rotation of the rotor 10 and by the evacuation unit 19 counteracting the rotation of the rotor 10. As seen in Fig. 1, the second blades 29 will rotate in the second rotational direction d2 opposite to the rotational direction d1 of the cyclone. The amount by which the second blades 29 counteract the rotation of the rotor 10, and by which the evacuation unit 19 is counteracting the rotation of the rotor 10, is given by the rotational velocity of the rotor 10, the angular velocity of the cyclone, and the flow rate of fluid flowing from the inflow opening 7 towards the outflow opening 9. Thereby, it is further ensured that the rotation of the rotor 10 is counteracted, i.e. braked, so that the guide blades 13 can provide a cyclone around the axis, and so that the angular velocity of the cyclone is more consistent at varying flow rates of fluid flowing from the inflow opening 7 towards the outflow opening 9. In addition, since the second blades 29 each have a pitch angle configured to counteract the rotation of the rotor 10, the rotational energy of the rotor 10 can be partially returned to the fluid flowing from the inflow opening 7 towards the outflow opening 9. Thereby, the pressure drop over the cyclone separator 1 can be reduced. Further, a straighter flow of fluid through the outflow opening 9 can be provided which also can reduce the pressure drop in a duct connected to the outflow opening 9 of the cyclone separator 1.

When the flow rate of fluid flowing from the inflow opening 7 towards the outflow opening 9 is low, the rotor 10 will rotate at a low rotational velocity in the second rotational direction d2. When the flow rate is higher, the rotor 10 will rotate at a higher rotational velocity in the second rotational direction d2. Due to the higher rotational velocity of the rotor 10 at high flow rates, the angular velocity of the cyclone will be lower than would be the case otherwise. As a result, the pressure drop over the cyclone separator 1 is reduced at high flow rates of fluid flowing from the inflow opening 7 towards the outflow opening 9. Conversely, when the flow rate is lower, the rotor 10 will rotate at a lower rotational velocity in the second rotational direction d2 which causes a higher angular velocity of the cyclone in the first rotational direction d1, than would be the case at the higher rotational velocity of the rotor 10 in the second rotational direction d2. Thereby, the separation efficiency of the cyclone separator 1 is increased at lower flow rates.

Thus, a cyclone separator 1 is provided in which the angular velocity of the cyclone is more consistent at varying flow rates of fluid flowing from the inflow opening 7 towards the outflow opening 9. As a result thereof, a cyclone separator 1 is provided having a more consistent separation efficiency and a more consistent pressure drop over the cyclone separator 1 at varying flow rates of fluid flowing from the inflow opening 7 towards the outflow opening 9. Accordingly, a cyclone separator 1 is provided capable of automatically adapting the separation efficiency and the pressure drop in dependence of the flow rate of fluid flowing from the inflow opening 7 towards the outflow opening 9. Further, the adaptation of the separation efficiency and the pressure drop is performed without having to use control arrangements, motors, or the like, which would have added manufacturing costs to the cyclone separator 1 .

According to the illustrated embodiments, the guide blades 13 and the second blades 29 are arranged at a distance from each other along the axis 11, and the guide blades 13 are arranged closer to the inflow opening 7 than the second blades 29. Further, according to the illustrated embodiments, the second blades 29 are arranged in the outflow opening 9. That is, according to the illustrated embodiments, the outflow opening 9 comprises the tube 28, wherein the tube 28 extends into the housing 5, and wherein the second blades 29 are arranged in the tube 28. Thereby, the second blades 29 will not disturb the cyclone and will not disturb the collection of particles in the particle collecting space 15. As a result thereof, the separation efficiency is improved. Further, since the second blades 29 are arranged in the tube 28, the rotational velocity of the rotor 10 is regulated without disturbing the cyclone, the rotational energy of the rotor 10 can be partially returned to the fluid without disturbing the cyclone, and an even straighter flow of fluid through the outflow opening 9 can be provided. As a result thereof, the separation efficiency is improved and the pressure drop over the cyclone separator 1 is reduced.

Further, according to the illustrated embodiments, the guide blades 13 together comprises a greater surface area in a direction of the axis 11 than the second blades 29. In addition, the pitch angle a2 of the second blades 29 is greater than the pitch angle a1 of the guide blades 13, and the pitch angle a2 of the second blades 29 are configured to accelerate the flow of fluid past the second blades 29 upon rotation of the rotor 10. As a result, the pressure drop over the cyclone separator 1 is further reduced, and it is ensured that the rotational energy of the rotor 10 is at least partially returned to the fluid and that a straighter flow of fluid through the outflow opening 9 is provided, which further reduces the pressure drop over the cyclone separator 1. The surface area of the second blades 29 in the direction of the axis 11 may for example be within the range of 10% - 70%, 15% - 50%, or 20% - 40% of the surface area of the guide blades 13 in the direction of the axis 11 .

Herein the pitch angle a1 of the guide blades 13 is defined as the angle a1 of the guide blades 13 in relation to a plane p perpendicular to the axis 11 . The pitch angle a1 may vary along a radial direction r of the guide blades 13. According to such embodiments, the pitch angle a1 may be defined as the average pitch angle along the radial direction r of the guide blades 13 in relation to the plane p perpendicular to the axis 11.

Further, herein the pitch angle a2 of the second blades 29 is defined as the angle a2 of the second blades 29 in relation to a plane p perpendicular to the axis 11. The pitch angle a2 may vary along a radial direction r of the second blades 29. According to such embodiments, the pitch angle a2 may be defined as the average pitch angle along the radial direction r of the second blades 29 in relation to the plane p perpendicular to the axis 11 .

As examples, the pitch angle a1 of the guide blades 13 may be within the range of 10 - 45 degrees, or within the range of 10 - 30 degrees, or within the range of 15 - 25 degrees, or approximately 20 degrees. The pitch angle a2 of the second blades 29 may be within the range of 50 - 85 degrees, or within the range of 60 - 80 degrees, or within the range of 65 -75 degrees, or approximately 70 degrees.

Fig. 2 illustrates a combustion engine 35 comprising an air intake arrangement 33, according to some embodiments. The air intake arrangement 33 is configured to duct ambient air to the combustion engine 35. The air intake arrangement 33 comprises the cyclone separator 1 illustrated in Fig. 1. The cyclone separator 1 is configured to separate particles from the air before the air is ducted to the combustion engine 35, where the air is led into cylinders of the combustion engine 35.

The flow rate of the air ducted to the combustion engine 35 varies to a great extent. That is, during idling or during low load situations, the flow rate of air is low and during high load situations the flow rate of air is high. However, since the air intake arrangement 33 comprises the cyclone separator 1, the air intake arrangement 33 is capable of adapting the separation efficiency and the pressure drop in dependence of the flow rate of ambient air ducted to the engine 35. Thus, an air intake arrangement 33 is provided with an improved separation efficiency at low load situations of the engine 35 and potentially with a lower pressure drop over the air intake arrangement 33 at high load situations of the engine 35. According to the illustrated embodiments, the air intake arrangement 33 further comprises a filter element 36. The filter element 36 is arranged downstream of the cyclone separator 1 . Thus, according to the illustrated embodiments, the cyclone separator 1 is arranged to separate particles from the air before the air is ducted to the filter element 36 where the air is subjected to further filtering before being ducted to the combustion engine 35. Since the air intake arrangement 33 is provided with an improved separation efficiency at low load situations of the combustion engine 35, the dust accumulation in the filter element 36 can be reduced, the operational time of the filter element 36 can be increased, the demands on the filter element 36 can be reduced, a low-price filter element 36 can be used, and/or a filter element 36 having a low pressure drop can be used. In addition, droplets of liquids, such as water, can be separated from the air in a more efficient manner over a wider operational range which may enhance the performance of the filter element 36 and prolong the life time of the filter element 36.

Further, air intake arrangement 33 circumvents the need for a complicated arrangement of ducts connecting the particle collecting space of the cyclone separator 1 to an ejector in an exhaust pipe of the combustion engine 35. Further, the forced evacuation of particles from the particle collecting space of the cyclone separator 1 is performed in an energy efficient manner having a low impact on the total fuel consumption of the combustion engine 35.

The combustion engine 35 is an internal combustion engine and may be a compression ignition engine, such as a diesel engine, or may be an Otto engine with a spark-ignition device, for example an Otto engine designed to run on gas, petrol, alcohol, similar volatile fuels or combinations thereof.

Fig. 3 illustrates a vehicle 37 comprising wheels 39 and the combustion engine 35 illustrated in Fig. 2. The combustion engine 35 is configured to provide motive power to the vehicle 37 via one or more of the wheels 39 of the vehicle 37.

The vehicle 37 illustrated in Fig. 3 is a truck. However, the combustion engine 35 may be comprised in another type of manned or unmanned vehicle for land or water based propulsion such as a lorry, a bus, a construction vehicle, a tractor, a car, a boat, a ship, or the like. Further, the combustion engine 35 as referred to herein may be a stationary combustion engine, for example a combustion engine configured to drive an electric generator.

It is to be understood that the foregoing is illustrative of various example embodiments and that the invention is defined only by the appended claims. A person skilled in the art will realize that the example embodiments may be modified, and that different features of the example embodiments may be combined to create embodiments other than those described herein, without departing from the scope of the present invention, as defined by the appended claims. Throughout this disclosure, the term “second blades” may be replaced with the term “counteracting blades”. Further, throughout this disclosure, the term “evacuation unit” may be replaced with the term “particle evacuation unit”, “ejector unit”, or “particle ejector unit”.

As used herein, the term "comprising" or "comprises" is open-ended, and includes one or more stated features, elements, steps, components or functions but does not preclude the presence or addition of one or more other features, elements, steps, components, functions or groups thereof.

Claims

1. A cyclone separator (1) configured to separate particles from a flow of fluid, wherein the cyclone separator (1) comprises: - a housing (5) comprising an inflow opening (7) and an outflow opening (9), and - a rotor (10) arranged inside the housing (5), wherein the rotor (10) is rotationally arranged around an axis (11) and comprises at least one guide blade (13) provided with a pitch angle (a1) configured to provide a cyclone around the axis (11), and configured to provide rotation of the rotor (10), when fluid is flowing from the inflow opening (7) towards the outflow opening (9), wherein the cyclone separator (1) further comprises a particle collecting space (15) and an evacuation unit (19) configured to perform a forced evacuation of particles from the particle collecting space (15), and wherein the evacuation unit (19) is configured to be driven by the rotation of the rotor (10).

2. The cyclone separator (1) according to claim 1, wherein the evacuation unit (19) is mechanically connected to the rotor (10).

3. The cyclone separator (1) according to claim 2, wherein the cyclone separator (1) comprises a shaft (21), and wherein the evacuation unit (19) is mechanically connected to the rotor (10) via the shaft (21).

4. The cyclone separator (1) according to any one of the preceding claims, wherein the evacuation unit (19) comprises an evacuation rotor (23) provided with at least one evacuation blade (25).

5. The cyclone separator (1) according to claim 4, wherein the evacuation rotor (23) is rotationally arranged around a second axis (27), and wherein the at least one evacuation blade (25) extends radially with respect to the second axis (27).

6. The cyclone separator (1) according to any one of the preceding claims, wherein the outflow opening (9) comprises a tube (28) extending into the housing (5), wherein the particle collecting space (15) is arranged between an inner wall (5.1) of the housing (5) and an outer wall (28.1) of the tube (28).

7. The cyclone separator (1) according to any one of the preceding claims, wherein the rotor (10) further comprises at least one second blade (29) having a pitch angle (a2) configured to counteract the rotation of the rotor (10) when fluid is flowing from the inflow opening (7) towards the outflow opening (9).

8. The cyclone separator (1) according to claim 7, wherein the at least one guide blade (13) and the at least one second blade (29) are arranged at a distance from each other along the axis (11).

9. The cyclone separator (1) according to claim 8, wherein the at least one guide blade (13) is arranged closer to the inflow opening (7) than the at least one second blade (29).

10. The cyclone separator (1) according to claim 6 and 7, wherein the at least one second blade (29) is arranged in the tube (28).

11. . The cyclone separator (1) according to any one of the claims 7 - 10, wherein the at least one guide blade (13) is provided with a greater surface area in a direction of the axis (11) than the at least one second blade (29).

12. The cyclone separator (1) according to any one of the claims 7 - 11, wherein the pitch angle (a2) of the at least one second blade (29) is configured to accelerate the flow of fluid past the at least one second blade (29) upon rotation of the rotor (10).

13. An air intake arrangement (33) for a combustion engine (35), wherein the air intake arrangement (33) is configured to duct ambient air to the combustion engine (35), and wherein the air intake arrangement (33) comprises a cyclone separator (1) according to any one of the preceding claims.

14. A combustion engine (35) comprising the air intake arrangement (33) according to claim 13.

15. A vehicle (37) comprising a combustion engine (35) according to claim 14.