Patent Grant
9512755
The present invention relates to a device for cleaning of polluted gas from a combustion engine, e.g. crankcase gas vented from a crankcase of a combustion engine, and in particular to a centrifugal separator for removal of pollutants suspended in the polluted gas in the form of solid or liquid particles.
Crankcase gas usually contains pollutants in the form of soot particles and/or oil mist.
EP 1273335 B1 describes such a known device for cleaning of crankcase gas. The centrifugal separator of the known device has a stationary housing which delimits within it a chamber in which the centrifuge rotor is arranged to rotate. The centrifugal separator is arranged to be fastened to the side of the combustion engine, and an external feed line is provided to lead crankcase gas from the engine to an inlet provided on the housing and communicating with the centrifuge rotor. During operation, the pollutants are separated from the crankcase gas by the rotating centrifuge rotor, and the housing has accordingly an outlet for the separated pollutants (oil and soot) and a gas outlet for the cleaned gas.
SE 529 409 C2 refers to a similar device for cleaning of crankcase gas. This centrifugal separator has a stationary housing which encloses the centrifuge rotor and which has an interface surface configured for direct mounting of the housing on a valve cover of the combustion engine. The interface surface is provided with a gas inlet which, via an aperture in the valve cover, communicates directly with the crankcase gas in a space defined by the valve cover. Such a configuration results in no need to provide an external crankcase gas feed line. The housing comprises also a gas outlet for the cleaned gas and a special gathering trough for the separated pollutants.
The prior art device has proved to be very effective for cleaning of polluted gas. Within the vehicle industry there are constantly increasing environmental requirements with a view to reducing emissions to the environment. The devices indicated above are traditionally used for cleaning of crankcase gas from large diesel engines. There is however a need to clean also crankcase gas from smaller combustion engines, e.g. diesel engines of the order of 5 to 9 liters or still smaller engines for passenger cars. At the same time, the automotive industry sets high requirements in terms of compact and cost-effective solutions exhibiting high performance.
An object of the present invention is to wholly or at least partly meet the above need.
According to the present invention, there is provided a device for cleaning polluted gas including a stack of separating discs on a centrifuge rotor, disposed for rotation in a space which is formed within a combustion engine and which is arranged to receive the polluted gas. The intermediate spaces between the separating discs communicate directly with the space, and the gas outlet is arranged to conduct the cleaned gas out from the space through a wall which delimits the space.
The device according to the invention thus utilises a space already present within the combustion engine. For cleaning of crankcase gas it is for example possible for such a space to take the form of the crankcase or a formed space situated within the engine block and communicating with the crankcase. Other possible spaces are those delimited by various kinds of covers belonging to the engine, e.g. the space within a valve cover, a timing chain case or a flywheel housing. For crankcase gas cleaning purposes, such spaces may be arranged to communicate with the crankcase through channels in the engine block. The space formed within the engine thus constitutes a delimited space for the centrifuge rotor. This means that the centrifugal separator needs neither a separate housing of its own to enclose the centrifuge rotor nor a separate feed line of its own to supply polluted gas to the centrifuge rotor. The device according to the invention occupies hardly any space outside the engine, since the whole or substantially the whole of the centrifugal separator is accommodated in the existing engine space. Nor does the centrifugal separator need to be provided with any outlet device for the pollutants separated from the gas. Instead, the centrifuge rotor is arranged, as a result of the counterflow separation, to propel the separated pollutants radially outwards from the stack of separating discs and directly back to the space which already contains polluted gas.
The centrifuge rotor may with advantage be situated in the space at such spacing from the delimiting wall that the polluted gas can flow relatively freely along the whole axial extent of the stack. This creates good conditions for the polluted gas to be distributed equally (homogeneously) to all the intermediate spaces between the separating discs. Owing to the limited space around a combustion engine, the prior art centrifugal separator is so configured that said stationary housing surrounds it relatively closely, i.e. the centrifugal separator is configured with a relatively small annular space between the centrifuge rotor and its surrounding housing. Such a small annular space may result in flow resistance causing uneven distribution of the polluted gas to the intermediate spaces in the stack of separating discs. The invention can therefore make improved separation performance possible in that the free flow along the whole stack of separating discs results in a more even distribution of the polluted gas to all the intermediate spaces between the separating discs.
Consequently, the invention proposes a device which results in effective cleaning of polluted gas from a combustion engine and which is both simple and compact.
According to an embodiment of the invention, the drive device is so arranged that the speed of the centrifuge rotor is variable relative to the speed of the combustion engine. By speed control, the centrifuge rotor speed and hence the cleaning effect can be adjusted as necessary. The centrifuge rotor may for example be drivingly connected to a shaft of the engine, wherein the drive device comprises means for a variable transmission ratio between said shaft and the centrifuge rotor so that the speed of the centrifuge rotor can be varied relative to the speed of the shaft and the engine.
According to another embodiment of the invention, the drive device is a motor. In this case the centrifuge rotor is driven by a motor of its own which is independent of the speed of the combustion engine. Such a motor also allows the possibility of speed control of the centrifuge rotor, which may for example be achieved by an electric motor operatively connected to a control unit for speed control of the electric motor and hence of the centrifuge rotor. The speed of a pneumatic or hydraulic motor may also be controlled by control of the flow of pressurised gas or liquid to the pneumatic or hydraulic motor.
According to another embodiment of the invention, the drive device is situated outside the space. The drive device is thus isolated from the space which contains polluted gas, which means for example that an electric motor can be protected from a relatively dirty and aggressive environment which contains oil mist, soot and other pollutants.
According to a further embodiment of the invention, a bearing unit is provided in the delimiting wall of the space, to rotatably support the centrifuge rotor in the wall. The wall is thus used as support for the centrifuge rotor. A further bearing unit may be provided in the space, in which case the bearing units are adapted to rotatably supporting the centrifuge rotor on their respective sides of the stack of separating discs. This results in relatively rigid journalling of the centrifuge rotor, whereby harmful vibrations and oscillations can be avoided during its rotation.
According to another embodiment of the invention, the centrifuge rotor is drivingly connected to the drive device via a rotor shaft which extends through a shaft lead-through in the delimiting wall of the space, the shaft lead-through being configured with said bearing unit in the wall. This means that the shaft lead-through can be used to rotatably support the centrifuge rotor in the wall.
According to a further embodiment of the invention, the centrifuge rotor is rotatably supported only in said bearing unit in the wall. This results in a simple support device for the whole centrifugal separator with only one bearing unit.
According to a further embodiment of the invention, the gas outlet communicates with the outlet chamber via an axial end wall which is situated on the stack of separating discs distally from said bearing unit in the wall. The gas outlet is thus disposed in the space on one axial side of the stack of separating discs, and the bearing unit is situated in the wall on the other axial side of the stack of separating discs.
According to a further embodiment of the invention, the gas outlet communicates with the outlet chamber via an axial end wall which is situated on the stack of separating discs proximally about said bearing unit in the wall. Both the gas outlet and the bearing unit are thus situated on the same axial side of the stack of separating discs.
According to a further embodiment of the invention, the gas outlet has the form of a tubular element which surrounds said bearing unit in the wall and which is connected to the delimiting wall of the space, which gas outlet forms an outlet duct in which a bearing support of the bearing unit is so arranged that cleaned gas can be conducted past the bearing support in the outlet duct. The result is a gas outlet combined with a bearing unit for rotatably supporting the centrifuge rotor in the wall.
According to a further embodiment of the invention, the motor is an electric motor. It is relatively easy to arrange a speed control for an electric motor. The electric motor is preferably situated outside the space so that it is isolated from the space containing the polluted gas and is therefore protected from the relatively dirty environment.
According to a further embodiment of the invention, the motor is a hydraulic or pneumatic motor arranged to rotate the centrifuge rotor by means of a fluid which is pressurised by the combustion engine during operation. Such a fluid may for example be compressed air or pressurised lubricant (oil) from an already present compressed air or lubricant system of a combustion engine for a vehicle, e.g. a truck.
According to a further embodiment of the invention, the motor comprises a turbine situated in the space and connected to the centrifuge rotor, which motor comprises a duct for supply of said pressurised fluid to an orifice provided in the space and directed towards the turbine in order to cause the turbine wheel and hence the centrifuge rotor to rotate. This means that the space can also be used for driving the centrifuge rotor. Pressurised lubricant (oil) may preferably be used as said pressurised fluid, since the space for the polluted gas is usually also configured to contain lubricant and/or to return said lubricant to, for example, the crankcase.
According to a further embodiment of the invention, the centrifugal separator comprises a fan situated downstream of the stack of separating discs and adapted to compensating for the pressure drop associated with the gas flow through the centrifuge rotor. In this case the gas outlet may be provided with a fan housing surrounding a fan impeller mounted on a rotor shaft which belongs to the centrifuge rotor and extends into the fan housing. In a counterflow separator, the centrifuge rotor exerts a pumping action on the gas flow in a direction opposite to the desired direction of flow, resulting in flow resistance through such a centrifuge rotor during operation. The rotating fan thus draws crankcase gas through the centrifuge rotor during operation. Excessive gas pressure in the space is thus avoided.
According to a further embodiment of the invention, the space formed within the combustion engine is delimited by a cover on the engine. Said wall delimiting the space may thus take the form of a valve cover, timing chain case, flywheel housing or the like. Such a cover arranged to delimit a space for receiving crankcase gas is prior art and not further described here.
According to another embodiment of the invention, the polluted gas is crankcase gas vented from a crankcase of the combustion engine. This means that the crankcase gas from the engine can be cleaned by the device. To this end, the space formed within the engine may be its crankcase or a space formed within the engine block and arranged to communicate with the crankcase.
The invention is explained in more detail below by a detailed description of embodiments of the invention described by way of examples with reference to the attached drawings.
In the space 4, 4′ the centrifuge rotor 3 is provided with a stack of separating discs 6 disposed at mutual spacing so that they delimit between them intermediate spaces 7 for crankcase gas to flow through. Such intermediate spaces 7 may be formed by providing a number of spacing members (not shown) on the surfaces of the separating discs. For the sake of clarity, the drawing shows only a small number of separating discs 6 with large axial intermediate spaces 7. In practice, significantly more separating discs 6 are stacked, with the result that relatively thin intermediate spaces 7 are formed between them. The stack of separating discs is disposed in the space 4 and 4′ in such a way that the intermediate spaces 7 between the separating discs 6 communicate directly with the space 4 and 4′. The separating discs 6 are of truncated conical shape and stacked between a first end wall 8 and a second end wall 9 which are of truncated conical shape corresponding to the separating discs 6. A rotor shaft 10 extends coaxially with the rotational axis R through the stack of separating discs 6, and the separating discs 6 and the end walls 8, 9 are disposed concentrically and connected to the rotor shaft 10. Each end wall 8, 9 and each separating disc 6 therefore have a central planar portion with a hole for the rotor shaft 10.
Each separating disc 6 further has running through it, in the planar portion, gas flow apertures (not shown) distributed around the rotor shaft 10. The gas flow apertures in the separating discs 6 and the intermediate spaces 7 between the central planar portions of the separating discs together form a central outlet chamber 11 within the stack of separating discs 6.
Consequently, the centrifuge rotor 3 is arranged to clean crankcase gas by so-called counterflow separation, wherein polluted crankcase gas is led into intermediate spaces 7 between the separating discs 6, radially from outside the rotor 3, and thence towards the central outlet chamber 11. The central portion of the second end wall 9 has running through it a plurality of apertures 12 distributed around the rotor shaft 10 so that the central outlet chamber 11 can communicate with a stationary gas outlet 13, 13′ and 13″ in order to discharge cleaned crankcase gas from the centrifuge rotor 3. The second end wall 9 further has an annular flange 14 which extends axially towards the gas outlet 13, 13′ and 13″ and is arranged to cooperate with a similar annular flange 15a on a tubular element 15b on the gas outlet 13, 13′ and 13″. The cleaned crankcase gas is thus guided from the central outlet chamber 11 to the stationary gas outlet 13, 13′ and 13″.
In the first embodiment shown in
In the second embodiment shown in
In the third embodiment shown in
The device described above and shown in the drawing works in the manner explained below for cleaning of crankcase gas from therein suspended particles (pollutants) which are of higher density than the gas. In this case the pollutants are of two kinds, viz. solid particles, e.g. soot particles, and liquid particles, e.g. oil particles.
The motor 19, 19′ maintains rotation of the centrifuge rotor 3 within the space 4, 4′. Polluted crankcase gas in the space 4, 4′ is led from an outer periphery of the stack of separating discs 6 directly into intermediate spaces 7 between the separating discs 6. From there, the gas flows radially inwards towards the central outlet chamber 11 of the rotor. While the gas is flowing between the separating discs 6, rotation is imparted to it by the rotation of the centrifuge rotor. The particles suspended in the gas are thus caused by the centrifugal force to move towards, and into contact with, the insides of the separating discs, i.e. the sides of the truncated conical separating discs which face towards the rotational axis R. Upon contact with the separating discs, the particles become entrained by them and are thereafter acted upon mainly by centrifugal forces which cause them to move radially outwards along the insides of the separating discs. When they reach the circumferential edges of the separating discs, the particles are propelled out from the centrifuge rotor 3 and are thus returned to the space 4, 4′.
The crankcase gas which has been relieved of particles in each intermediate space between neighbouring separating discs 6 continues to move radially inwards to the central outlet chamber 11 in the centrifuge rotor 3. However, the rotation of the centrifuge rotor results in flow resistance on the gas flowing through the intermediate spaces 7 between the separating discs 6. In other words, the centrifuge rotor 3 exerts a pumping action on the gas flow in a direction opposite to the desired direction of flow through the centrifuge rotor. If during operation the crankcase gas formed which is supplied to the space 4, 4′ generates a high enough gas pressure therein, it will be caused, despite said flow resistance, to flow radially inwards towards the central outlet chamber 11 and out through the gas outlet 13′. However, the engine is so dimensioned that the pressure within the space 4, 4′ needs to be kept within a specific pressure range, i.e. the pressure should not be allowed rise above a certain positive pressure, nor fall below a certain negative pressure. If the permissible positive pressure in the space 4, 4′ is not sufficient to push the crankcase gas through the rotating centrifuge rotor, the device may be provided with said fan impeller 16 situated downstream of the centrifuge rotor to compensate for the pressure drop associated with the gas flow through the centrifuge rotor. The rotating fan impeller 16 thus draws crankcase gas through the centrifuge rotor 3 during operation. The cleaned crankcase gas leaves the outlet chamber 11 of the rotor 3 through the gas outlet 13, 13′ and 13″.
The invention is not confined to the embodiments referred to but may be varied and modified within the scope of the claims set out below. In the embodiments referred to, the centrifuge rotor is disposed horizontally in the space, but it may also be disposed vertically therein. Thus the centrifuge rotor may for example be arranged to hang in the valve cover via the rotor shaft and the bearing unit in the wall, or via the rotor shaft and the motor situated outside the space. The truncated conical separating discs may also be oriented with their inside facing either towards (as shown in the drawings) or away from the gas outlet. If they face away from the gas outlet, the first end wall 8 will instead be provided with a plurality of apertures running through it so that the central outlet chamber can communicate with the gas outlet in order to discharge cleaned gas from the centrifuge rotor.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1050350 | Apr 2010 | SE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/SE2011/050398 | 4/5/2011 | WO | 00 | 12/4/2012 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2011/126436 | 10/13/2011 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 1420665 | Newcombe | Jun 1922 | A |
| 2344068 | Waseige | Mar 1944 | A |
| 3022776 | Steinlein et al. | Feb 1962 | A |
| 4329968 | Ishikawa | May 1982 | A |
| 4723529 | Yokoi et al. | Feb 1988 | A |
| 5129371 | Rosalik, Jr. | Jul 1992 | A |
| 5487371 | Beckman | Jan 1996 | A |
| 5542402 | Lee | Aug 1996 | A |
| 5564401 | Dickson | Oct 1996 | A |
| 5746789 | Wright et al. | May 1998 | A |
| 5954035 | Hofer | Sep 1999 | A |
| 6152120 | Julazadeh | Nov 2000 | A |
| 6216453 | Maurer | Apr 2001 | B1 |
| 6364822 | Herman et al. | Apr 2002 | B1 |
| 6536211 | Borgstrom | Mar 2003 | B1 |
| 6584964 | Seilenbinder | Jul 2003 | B1 |
| 6626163 | Busen | Sep 2003 | B1 |
| 6709477 | Håkansson | Mar 2004 | B1 |
| 6755896 | Szepessy et al. | Jun 2004 | B2 |
| 6925993 | Eliasson et al. | Aug 2005 | B1 |
| 6973925 | Sauter et al. | Dec 2005 | B2 |
| 7033411 | Carlsson et al. | Apr 2006 | B2 |
| 7052529 | Franzen et al. | May 2006 | B2 |
| 7056363 | Carlsson et al. | Jun 2006 | B2 |
| 7152589 | Ekeroth et al. | Dec 2006 | B2 |
| 7250066 | Seipler | Jul 2007 | B2 |
| 7338546 | Eliasson et al. | Mar 2008 | B2 |
| 7445653 | Trautmann et al. | Nov 2008 | B2 |
| 7632326 | Stemmer | Dec 2009 | B2 |
| 7811347 | Carlsson et al. | Oct 2010 | B2 |
| 7927395 | Szepessy et al. | Apr 2011 | B2 |
| 8075655 | Anderson et al. | Dec 2011 | B2 |
| 8123829 | Sato et al. | Feb 2012 | B2 |
| 8172917 | Kup et al. | May 2012 | B2 |
| 8191537 | Moy | Jun 2012 | B1 |
| 8714132 | Baumann et al. | May 2014 | B2 |
| 20020026928 | Korenjak | Mar 2002 | A1 |
| 20020032088 | Korenjak | Mar 2002 | A1 |
| 20020033295 | Korenjak | Mar 2002 | A1 |
| 20020112710 | Akiwa | Aug 2002 | A1 |
| 20030000508 | Takahashi | Jan 2003 | A1 |
| 20030019484 | Lepp | Jan 2003 | A1 |
| 20030070982 | Baek | Apr 2003 | A1 |
| 20030178014 | Sauter | Sep 2003 | A1 |
| 20030233932 | Ekeroth | Dec 2003 | A1 |
| 20040025482 | Borgstrom et al. | Feb 2004 | A1 |
| 20040107681 | Carlsson et al. | Jun 2004 | A1 |
| 20040144071 | Hilpert | Jul 2004 | A1 |
| 20040159085 | Carlsson et al. | Aug 2004 | A1 |
| 20040168415 | Hilpert | Sep 2004 | A1 |
| 20050120685 | Fischer | Jun 2005 | A1 |
| 20050121262 | Berger | Jun 2005 | A1 |
| 20060075998 | Shieh | Apr 2006 | A1 |
| 20060090738 | Hoffmann | May 2006 | A1 |
| 20060226155 | Roche | Oct 2006 | A1 |
| 20060249128 | Shieh | Nov 2006 | A1 |
| 20070294986 | Beetz | Dec 2007 | A1 |
| 20080041324 | Matsushima | Feb 2008 | A1 |
| 20080135030 | Knaus | Jun 2008 | A1 |
| 20080264251 | Szepessy | Oct 2008 | A1 |
| 20090000300 | Hilpert | Jan 2009 | A1 |
| 20090025562 | Hallgren | Jan 2009 | A1 |
| 20090025662 | Herman | Jan 2009 | A1 |
| 20090044791 | Rice | Feb 2009 | A1 |
| 20090205618 | Hirota | Aug 2009 | A1 |
| 20090223496 | Borgstrom | Sep 2009 | A1 |
| 20090241920 | Inge | Oct 2009 | A1 |
| 20090266346 | Wagner | Oct 2009 | A1 |
| 20090308249 | Anderson | Dec 2009 | A1 |
| 20100011723 | Szepessy | Jan 2010 | A1 |
| 20100043734 | Holzmann | Feb 2010 | A1 |
| 20100051388 | Clark | Mar 2010 | A1 |
| 20100126480 | Shieh | May 2010 | A1 |
| 20100180854 | Baumann | Jul 2010 | A1 |
| 20100232955 | Schick et al. | Sep 2010 | A1 |
| 20110011380 | Lagerlof | Jan 2011 | A1 |
| 20110023849 | Cattani | Feb 2011 | A1 |
| 20110281712 | Schlamann | Nov 2011 | A1 |
| 20120318215 | Copley | Dec 2012 | A1 |
| 20130067873 | Szepessy | Mar 2013 | A1 |
| 20130125857 | Mayr | May 2013 | A1 |
| 20140048052 | Subedi | Feb 2014 | A1 |
| 20140165977 | Copley | Jun 2014 | A1 |
| 20140230381 | Tornblom | Aug 2014 | A1 |
| 20140352539 | Schleiden | Dec 2014 | A1 |
| 20150020785 | An | Jan 2015 | A1 |
| 20150068172 | Andersson Aginger | Mar 2015 | A1 |
| 20150114368 | Kurita | Apr 2015 | A1 |
| 20150119226 | Pogen | Apr 2015 | A1 |
| 20150159596 | Wakiya | Jun 2015 | A1 |
| 20150167591 | Sato | Jun 2015 | A1 |
| 20150345351 | Mincher | Dec 2015 | A1 |
| 20150361839 | Kimura | Dec 2015 | A1 |
| 20160024984 | Galeazzi | Jan 2016 | A1 |
| 20160082378 | Ishida | Mar 2016 | A1 |
| 20160177791 | Kira | Jun 2016 | A1 |
| Number | Date | Country |
|---|---|---|
| 101384329 | Mar 2009 | CN |
| 10163924 | Jul 2003 | DE |
| 10350562 | Jun 2005 | DE |
| 1273335 | Jan 2003 | EP |
| 1645320 | Apr 2006 | EP |
| 1645320 | Apr 2006 | EP |
| 1772193 | Apr 2007 | EP |
| 1772193 | Apr 2008 | EP |
| 1963631 | Jan 2010 | EP |
| 2317203 | Mar 1998 | GB |
| 57-002411 | Jan 1982 | JP |
| 04-153514 | May 1992 | JP |
| H08-284634 | Oct 1996 | JP |
| 10-274024 | Oct 1998 | JP |
| 2000-45749 | Feb 2000 | JP |
| 2005-042698 | Feb 2005 | JP |
| 2008-155093 | Jul 2008 | JP |
| 2310760 | Nov 2007 | RU |
| 2315872 | Jan 2008 | RU |
| 519180 | Jan 2003 | SE |
| 529409 | Aug 2007 | SE |
| 01-36103 | May 2001 | WO |
| 2004024297 | Mar 2004 | WO |
| 2007073320 | Jun 2007 | WO |
| WO 2008005481 | Mar 2008 | WO |
| WO 2009065660 | May 2009 | WO |
| WO 2009010248 | Jun 2009 | WO |
| Entry |
|---|
| EP 1645320 A1 as translated by Google. |
| International Search Report for International Application No. PCT/SE2011/050398, dated Aug. 3, 2011. |
| International Preliminary Report on Patentability for International Application No. PCT/SE2011/050398, dated Jun. 29, 2012. |
| First Office Action for Japanese Patent Application No. 2013-50371, dated Oct. 1, 2013. |
| Number | Date | Country | |
|---|---|---|---|
| 20130067873 A1 | Mar 2013 | US |
