A CRANKCASE VENTILATION SYSTEM FOR AN INTERNAL COMBUSTION ENGINE

Abstract

A crankcase ventilation system is provided for an internal combustion engine that includes a crankcase. An internal combustion engine including such a system is also provided.

Claims

1. A crankcase ventilation system for an internal combustion engine comprising a crankcase, the system comprising: a first filter arrangement arranged for cleaning a crankcase gas generated during operation of the engine, the first filter arrangement comprising a filter element for cleaning the crankcase gas, a device for altering a temperature of the crankcase gas towards a desired temperature, at which the first filter arrangement is adapted for an efficient cleaning, wherein the temperature altering device is adapted for cooling the crankcase gas, and wherein the filter element is of an oleophobic type.

2. (canceled)

3. (canceled)

4. The system according to claim 1, wherein the filter element is of an expanded oleophobic type.

5. The system according to claim 4, wherein a porosity of the membrane is at least 80%.

6. The system according to claim 1, wherein the temperature altering device is adapted for controlling the temperature of the crankcase gas towards the desired temperature.

7. (canceled)

8. The system according to claim 1, wherein the temperature altering device comprises a first conduit arranged for connection to the crankcase at a first end and to the first filter arrangement at a second end.

9. The system according to claim 8, wherein the first conduit is configured for active cooling of the crankcase gas flowing through the first conduit.

10. The system according to claim 1, wherein the temperature altering device comprises a control unit and a temperature sensor, wherein the temperature sensor is electrically connected to the control unit and configured to measure a temperature of the crankcase gas, wherein the control unit is configured for comparing the sensed temperature with a predetermined threshold and to generate a control signal if the sensed temperature is above the predetermined threshold.

11. The system according to claim 1, wherein the temperature altering device comprises a fan for cooling the contaminated crankcase gas.

12. The system according to claim 8, wherein the temperature altering device comprises a fan for cooling the contaminated crankcase gas, and wherein the first conduit is arranged for being subjected to an air flow produced by the fan.

13. The system according to claim 8, wherein the temperature altering device comprises a means arranged to circulate a coolant in proximity to first conduit for cooling of the contaminated crankcase gas flowing through the first conduit.

14. The system according to claim 1, wherein the temperature altering device further comprises a heat exchanger operatively connected with a cooling system of the engine.

15. The system according to claim 8, wherein the first conduit is configured for passive cooling of the contaminated crankcase gas flowing through the first conduit.

16. The system according to claim 8, wherein the first conduit is arranged on a cool side of the engine.

17. The system according to claim 1, wherein the filter element is arranged to have a spherical form.

18. The system according to claim 1, wherein the filter element is arranged to have a cylindrical form.

19. The system according to claim 1, wherein a surface area of the filter element is at least 0.01 m2, preferably at least 0.015 m2.

20. The system according to claim 1, further comprising a second filter arrangement corresponding to the first filter arrangement, wherein the second filter arrangement is arranged in series with the first filter arrangement, downstream of the first filter arrangement.

21. The system according to claim 20, wherein a crankcase gas outlet comprised with the first filter arrangement is connected to a crankcase gas inlet comprised with the second filter arrangement.

22. The system according to claim 1, wherein the first filter arrangement further comprises a contaminant outlet provided at the housing and configured to release contaminants to an oil sump comprised with the engine.

23. The system according to claim 1, wherein the system is configured to recirculate the crankcase gas through the first filter arrangement.

24. The system according to claim 23, further comprising a controllable valve mechanism configured to adjust a level of crankcase gas recirculation based on a crankcase gas pressure.

25. The system according to claim 24, wherein the valve mechanism is configured to be controlled based on a crankcase gas pressure in the crankcase.

26. The system according to claim 1, further comprising a fan configured to control a flow of the crankcase gas flowing through the first filter arrangement.

27. An internal combustion engine including a crankcase and further comprising a crankcase ventilation system according to claim 1.

28. A vehicle comprising an engine according to claim 27.

29. The system according to claim 1, wherein the temperature altering device is adapted to cool the crankcase gas to between 250-320 degrees C. once the crankcase gas reaches the first filter arrangement.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The various aspects of the invention, including its particular features and advantages, will be readily understood from the following detailed description and the accompanying drawings, in which:

[0025] FIG. 1 illustrates a vehicle equipped with an internal combustion engine according to the invention;

[0026] FIG. 2 conceptually illustrates an internal combustion engine equipped with a crankcase ventilation system;

[0027] FIGS. 3a and 3b conceptually illustrates a first and a second embodiment of the crankcase disclosed ventilation system, and

[0028] FIGS. 4a and 4b conceptually illustrates a first and a second currently preferred embodiment of a filter element comprised with the crankcase ventilation system.

DETAILED DESCRIPTION

[0029] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled addressee. Like reference characters refer to like elements throughout.

[0030] Referring now to the drawings and to FIG. 1 in particular, there is depicted an exemplary vehicle, here illustrated as a truck 100. The truck 100 is provided with a source of motive power 102 for propelling the truck via a driveline connecting the power source to the wheels. The power source 102 is constituted by an internal combustion engine (ICE) in the form of a diesel engine. It will in the following for ease of presentation be referred to as an internal combustion engine 102.

[0031] FIG. 2 shows the internal combustion engine 102 equipped with a crankcase ventilation system 200 according to the invention.

[0032] During use of the ICE 102, ambient air will be drawn though an air filter 202, pass a turbo 204 and into an upper part of a cylinder 206, above a piston 208, where it will be mixed with a fuel, such as for example diesel or petrol. As the air/fuel mixture in the cylinder 206 is ignited, portions of the combustion gases will leak past the sides of the piston 208 (past piston ring(s) of the piston) and into a crankcase 210 comprised with the ICE 102.

[0033] The combustion gases entering the crankcase 210 comprise contaminants, such as for example soot particles. The combustion gases will further come in contact with and be partly mixed with further contaminants comprised in the crankcase 210, such as oil, forming a contaminated crankcase gas. A pressure formed by the combustion gases entering the crankcase 210 needs to be vented in a controlled manner, in accordance to the present disclosure through the crankcase ventilation system 200. The crankcase gas is allowed to exit the crankcase 210 through an outlet 212, for example arranged at an upper portion of the ICE 102, other placements of such an outlet is of course possible and within the scope of the invention.

[0034] A first conduit 214 is provided for transporting the crankcase gas from the outlet 212 of the ICE 102 to an inlet 216 of the crankcase ventilation system 200. The crankcase gas is cleaned inside of the crankcase ventilation system 200, as will be further discussed below, and a cleaned crankcase gas will be released through a first outlet 218 of the crankcase ventilation system 200. A fan function may be provided inside of and/or outside of the crankcase ventilation system 200 for assisting the transportation of the crankcase gas through the crankcase ventilation system 200. The cleaned crankcase gas may for example, as illustrated in FIG. 2, be mixed with ambient air before entering the turbo 204. A second conduit 220 may be provided for connecting the first outlet 218 of the crankcase ventilation system 200 to the turbo 204. Alternatively, the cleaned crankcase gas may be allowed to enter the atmosphere, possibly passing through further filters members before doing so.

[0035] The contaminants/particles having been removed from the contaminated crankcase gas are preferably passed back to an oil sump comprised with the ICE 102 through a second outlet 222 of the crankcase ventilation system 200 and by a third conduit 224. Furthermore, it should be noted that it is desirable to arrange some form of check valve (one-way valve) functionality between the second outlet 222 of the crankcase ventilation system 200 and the crankcase 210, thereby only allowing contaminants to be passed back to the crankcase 210 and not allowing contaminated crankcase gases to be sucked backwards into the crankcase ventilation system 200.

[0036] Turning now to FIG. 3a, which illustrates an exemplary embodiment of a single stage crankcase ventilation system 200 that may be used together with the ICE 102. In the illustrated embodiment, the crankcase ventilation system 200 comprises a first filter arrangement 300. The first filter arrangement 300 in turn comprises a housing 302 having a gas inlet 304 and a gas outlet 306. The first conduit 214 is arranged to be connected to the gas inlet 304 and the second conduit 220 is arranged to be connected to the gas outlet 306. The housing 302 further comprises a contaminant outlet 308 arranged to be connected to the third conduit 224.

[0037] The first filter arrangement 300 further comprises a filter element in the form of an expanded oleophobic membrane 310 formed as a cylinder, further discussed below in relation to FIGS. 4a and 4b.

[0038] In addition, the crankcase ventilation system 200 further comprises a passive temperature altering device, in the illustrated embodiment implemented by means of heat flanges 312 arranged together with the first conduit 214.

[0039] During operation of the crankcase ventilation system 200, the crankcase gas will be sucked from the crankcase, by the outlet 212 and through the first conduit 214. When passing the first conduit 214, ambient air for example by the first conduit 214 being arranged on a cold side of the ICE 102 (completely passive cooling) or in the vicinity of a fan (not shown, providing semi-passive cooling) comprised with the ICE 102 will alter the temperature of the crankcase gas, before the crankcase gas reaches the first filter arrangement 300. The design of the heat flanges 312 may for example be selected such that the crankcase gas once reaching the first filter arrangement 300 has a desired temperature essentially matches a filtration temperature of the expanded oleophobic membrane 310 where the cleaning of the crankcase gas reaches is performed as is desired for the specific implementation. The temperature of the crankcase gas may for example be altered such that the amount of contaminants adhering to an inside surface of the expanded oleophobic membrane 310 is reduced, and/or such that a gas flow through the expanded oleophobic membrane 310 is kept above a predetermined threshold. In an embodiment, the heat flanges 312 are implemented such that the temperature of the crankcase gas is between 250-320 degrees C. once the crankcase gas reaches the first filter arrangement 300.

[0040] Once the crankcase gas reaches the first filter arrangement 300, the expanded oleophobic membrane 310 will inhibit the passage of e.g. liquid contaminants comprised with the crankcase gas. The liquid contaminants will accordingly stay on the inside of the cylindrically formed expanded oleophobic membrane 310. The non-sticky properties of the expanded oleophobic membrane 310 will together with gravitation then force the liquid contaminants towards a downward pointing conical bottom section 316 of the housing 302 of the first filter arrangement 300, eventually reaching the contaminant outlet 308, to subsequently reach the oil sump 314 of the ICE 102, for further use during operation of the ICE 102.

[0041] In the illustrated embodiment the gas inlet 304 of the first filter arrangement 300 is further provided with a passage 318, allowing the liquid contaminants to pass downward to the bottom section 316 of the housing 302. The passage 318 is arranged to at least partly encircle the gas inlet 304 of the housing 302.

[0042] In the illustrated embodiment the housing 302 comprises the mentioned bottom section 316 and a top section 320. In a possible embodiment of the invention the bottom section 316 and the top section 320 may be separated (i.e. detachably connected), allowing the expanded oleophobic membrane 310 to be exchanged once its lifetime has passed, e.g. when performing service of the ICE 102. Alternatively, all of the first filter arrangement is exchanges once the crankcase ventilation system 200 is serviced.

[0043] Turning now to FIG. 3b, which illustrates an alternative exemplary embodiment of the crankcase ventilation system 200, here presented in the form of a multi-stage crankcase ventilation system 200. In addition to the first filter arrangement 300 comprised with the single stage crankcase ventilation system 200 shown in FIG. 3a, the multi-stage crankcase ventilation system 200 further comprises a second filter arrangement 322 corresponding to the first filter arrangement 300, wherein the second filter arrangement 322 is arranged in series with the first filter arrangement 300, downstream of the first filter arrangement 300.

[0044] Preferably, the second filter arrangement 322 is arranged such that the gas outlet 306 of the first filter arrangement 300 is connected to a gas inlet 324 of the second filter arrangement 322, comprised with a housing 326 of the second filter arrangement 322. The second filter arrangement 322 further comprises a gas outlet 328 connected to the second conduit 220. The second filter arrangement 322 further comprises a corresponding expanded oleophobic membrane 310 as comprised with the first filter arrangement 300.

[0045] As mentioned, the crankcase ventilation system 200 shown in FIG. 3a comprises a passive temperature altering device. In comparison, the crankcase ventilation system 200 shown in FIG. 3b is provided with an active temperature altering device, implemented by means of a heat exchanger 330. In the illustrated embodiment, the heat exchanger 330 is arranged with the first conduit 214, such that the crankcase gas is allowed to flow through the heat exchanger 330. The heat exchanger 330 is in turn connected to e.g. a cooling circuit (not shown) of the ICE 102. The flow of a coolant flowing through the heat exchanger 330 may be controlled by e.g. a valve 334 provided with the heat exchanger 330.

[0046] During operation of the crankcase ventilation system 200 shown in FIG. 3b, a temperature of the crankcase gas may be monitored, for example using a temperature sensor 336 arranged at a vicinity to the gas inlet 324. A control unit 338 may for example be arranged to sample a signal from the temperature sensor 336, determine a temperature of the crankcase gas and comparing the determined temperature with a predetermined threshold. In case the temperature is outside of a predetermined threshold/temperature range (e.g. the above mentioned 250-320 degrees C.), the valve 334 may be controlled for increasing or decreasing the flow of the coolant flowing through the heat exchanger 330, thereby altering the temperature of the crankcase gas towards the desired temperature/temperature range. It could also be possible to allow a heated fluid to be circulated through the heat exchanger 330, thereby allowing the crankcase gas to be heated towards the desired temperature.

[0047] As mentioned above, by means of introducing the second filter arrangement 322, it may be possible to adapt e.g. parameters of the expanded oleophobic membrane 310, for example allowing a higher pass-through, providing less reduction of a pressure drop of the crankcase gas with e.g. the same level of cleaning of the crankcase gas. Alternatively, an increased cleaning of the crankcase gas may be implemented as the crankcase gas has to pass through two separate and essentially identical filter arrangements.

[0048] It should be understood that it also may be possible to alternatively arrange the first filter arrangement 300 in parallel with the second filter arrangement 322. Such an implementation could allow for improved redundancy. In addition, liquid contaminants from both the first 300 and the second 322 filter arrangements may both be collected within the oil sump 314.

[0049] Turning finally to FIGS. 4a and 4b, conceptually illustrates a first and a second currently preferred embodiment of a filter element comprised with the crankcase ventilation system.

[0050] In the first embodiment of the filter element as shown in FIG. 4a, the filter element is arranged as the cylindrically formed expanded oleophobic membrane 310, for example shown in FIGS. 3a and 3b.

[0051] In the second embodiment of the filter arrangement as shown in FIG. 4b, the filter element is arranged as a spherical formed expanded oleophobic membrane 402. The form of the filter element is typically depending on the implementation at hand, and possible real-estate constraints posed when implementing the ICE 102 with the truck 100. In any case and as mentioned above, it is desirable to select the form such that a surface area is large enough for only imposing a smaller pressure drop to the crankcase gas. In a specific embodiment the surface area of the filter element is at least 0.01 m2, preferably at least 0.015 m2.

[0052] In summary, the present invention relates to a crankcase ventilation system for an internal combustion engine comprising a crankcase, the system comprising a first filter arrangement arranged for cleaning a crankcase gas generated during operation of the engine, wherein the system comprises a device for altering a temperature of the crankcase gas towards a desired temperature, at which the first filter arrangement is adapted for an efficient cleaning.

[0053] By means of the inclusion of a temperature altering device with the crankcase ventilation system, it is possible to adapt a temperature of the crankcase gas such that the first filter arrangement is allowed to operate where an effective level of cleaning of the crankcase gas is made possible, where the temperature may be targeted to the specific type of first filter arrangement.

[0054] Even though the present disclosure has been described with reference to specific exemplifying embodiments thereof, many different alterations, modifications and the like will become apparent for those skilled in the art from a study of the drawings, the disclosure, and the appended claims. In addition, in the claims, the word comprising does not exclude other elements or steps, and the indefinite article a or an does not exclude a plurality.