A METHOD FOR REMOVING LEAKED CRANKCASE FLUID FROM A CRANKCASE AND A CRANKCASE VENTILATION SYSTEM

Abstract

A method is provided for removing leaked crankcase fluid from a crankcase of an internal combustion engine during operation thereof, the method including the steps of measuring as operation parameter value of the internal combustion engine; comparing the measured operation parameter value with a preset parameter range defining a mode of operation of the internal combustion engine for determining if the internal combustion engine is in the mode of operation; guiding the leaked crankcase fluid from the crankcase to an intake of the internal combustion engine if it is determined that the internal combustion engine is in the mode of operation; and guiding the leaked crankcase fluid from the crankcase to an ambient environment of the internal combustion engine if it s determined that the internal combustion engine is not in the mode of operation.

Claims

1. A method for removing leaked crankcase fluid from a crankcase (217) of an internal combustion engine (100) during operation thereof, the method comprising the steps of: measuring (S1) an operation parameter value (308) of the internal combustion engine (100); comparing (S2) the measured operation parameter value (308) with a preset parameter range (306) defining a mode of operation of said internal combustion engine (100) for determining (S3) if said internal combustion engine is in the mode of operation; guiding (S4) said leaked crankcase fluid from the crankcase (217) to an intake (203) of the internal combustion engine if it is determined that said internal combustion engine is in the mode of operation; and guiding (S5) said leaked crankcase fluid from the crankcase (217) to an ambient environment of the internal combustion engine if it is determined that said internal combustion engine is not in said mode of operation.

2. The method according to claim 1, wherein it is determined that said internal combustion (100) engine is exhibiting a normal mode of operation if it is in said mode of operation.

3. The method according to claim 2, wherein the engine exhibits normal mode of operation if the measured operation parameter value is within said preset parameter range (306).

4. The method according to any of the previous claims, wherein the step of guiding (S4) the leaked crankcase fluid from the crankcase (217) to the intake (203) of the internal combustion engine (100) is executed by means of controlling a valve (210).

5. The method according to claim 4, wherein the valve (210) is positioned downstream of said crankcase (217) such that it is arranged in fluid communication with the crankcase (217) and the intake (203) of the internal combustion engine (100).

6. The method according to any one of the preceding claims, wherein the step of guiding (S5) the leaked crankcase fluid from the crankcase (217) to the ambient environment of the internal combustion engine (100) is executed by controlling the valve (210) such that a pressure from the crankcase fluid on a relief valve (208), arranged in fluid communication with the crankcase (217) and the ambient environment, exceeds a predetermined threshold limit.

7. The method according to any one of the preceding claims, wherein the operation parameter value is one of crankcase pressure, engine speed and exhaust temperature, or any combination thereof.

8. A crankcase ventilation system (206) for removing leaked crankcase fluid from a crankcase (217) of an internal combustion engine (100), the crankcase ventilation system (206) comprising: a valve (210) configured to be arranged in fluid communication with a crankcase (217) of the internal combustion engine (100) and an intake (203) of the internal combustion engine (100); and a control unit (211) connectable to said valve (210), wherein said control unit (211) is configured to: receive an operation parameter value (308) of the internal combustion engine (100); compare the received operation parameter value (308) with a preset parameter range (306) defining a mode of operation of said internal combustion engine (100) to determine if said internal combustion engine (100) is in the mode of operation; control said valve (210) to guide leaked crankcase fluid from the crankcase (217) to the intake (203) of the internal combustion engine (100) if it is determined that the internal combustion engine (100) is in the mode of operation; and control said valve (210) to guide leaked crankcase fluid from the crankcase (100) to an ambient environment of the internal combustion engine (100) if it is determined that the internal combustion engine is not in the mode of operation.

9. The crankcase ventilation system (206) according to claim 8, wherein the control unit (211) is configured to position the valve (210) in an open state if it is determined that the internal combustion engine (100) is in the mode of operation.

10. The crankcase ventilation system (206) according to claim 8 or 9, further comprising a relief valve (208) configured to be arranged in fluid communication with the crankcase (217) and an outlet to the ambient environment of the internal combustion engine (100), wherein leaked crankcase fluid from the crankcase (217) is configured to be guided through the relief valve (208) if it is determined that the internal combustion engine (100) is not in the mode of operation.

11. The crankcase ventilation system (206) according to any one of claims 8-10, further comprising an oil mist separator (204), wherein the valve (210) is positioned downstream said oil mist separator (204).

12. The crankcase ventilation system (206) according to claim 11, wherein the valve (210) forms an integrated part of the oil mist separator (204).

13. The crankcase ventilation system (206) according to claim 11 when dependent on claim 10, wherein the relief valve (208) is positioned downstream the oil mist separator (204).

14. The crankcase ventilation system (206) according to claim 11 when dependent on claim 10, wherein the relief valve (208) forms an integrated part of the oil mist separator (204)

15. The crankcase ventilation system (206) according to claims 8-14, further comprising a pilot valve configured to position the valve (210) in the open or closed state.

16. The crankcase ventilation system (206) according to claim 15, wherein the pilot valve is connectable to the control unit (211) and configured to position the valve (210) in the open or closed state as a response to a signal received from the control unit (211).

17. The crankcase ventilation system (206) according to claim 15, wherein the pilot valve is configured to position the valve (210) in the open or closed state by means of pressure generated in the intake (203) of the internal combustion engine.

18. The crankcase ventilation system (206) according to any one of claims 8-17, further comprising a by-pass valve (216) arranged in fluid communication with the valve (210) and the intake (203) of the internal combustion engine (100).

19. A control unit (211) electrically connectable to a valve (210) of a crankcase ventilation system (206) of an internal combustion engine (100), wherein the control unit (211) is configured to: receive an operation parameter value (308) of the internal combustion engine (100); compare the received operation parameter value (308) with a preset parameter range (306) defining a mode of operation of said internal combustion engine (100) to determine if said internal combustion engine (100) is in the mode of operation; control said valve (210) to guide leaked crankcase fluid from the crankcase (217) to an intake (203) of the internal combustion engine (100) if it is determined that the internal combustion engine is in the mode of operation; and control said valve (210) to guide leaked crankcase fluid from the crankcase (217) to an ambient environment of the internal combustion engine (100) if it is determined that the internal combustion engine is not in the mode of operation.

20. An internal combustion engine (100), comprising a crankcase ventilation system (206) according to any one of claims 8-18.

21. A crankcase ventilation system for removing leaked crankcase fluid from a crankcase (217) of an internal combustion engine (100), the crankcase ventilation system comprising: an oil mist separator (204) configured to be positioned downstream the crankcase (217) and arranged in fluid communication with the crankcase (217) and an intake (203) of the internal combustion engine (100); and a relief valve (208) configured to be positioned downstream the oil mist separator (204) and arranged in fluid communication with the oil mist separator (204), the intake (203) of the internal combustion engine (100), and an ambient environment of the internal combustion engine (100).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The above, as well as additional objects, features and advantages of the present invention, will be better understood through the following illustrative and non-limiting detailed description of exemplary embodiments of the present invention, wherein:

[0053] FIG. 1 is a side view of a vehicle comprising an internal combustion engine provided with a crankcase ventilation system according to an example embodiment of the present invention;

[0054] FIG. 2 is a schematic view of the crankcase ventilation system according to an example embodiment of the present invention;

[0055] FIG. 3 is a graph illustrating an example of measured temperature and preset temperature as a function of time; and

[0056] FIG. 4 illustrates a flow-chart of the method steps according to an example embodiment of the present invention.

DETAIL DESCRIPTION

[0057] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which an exemplary embodiment of the invention is shown. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiment set forth herein; rather, these embodiments are provided for thoroughness and completeness. Like reference character refer to like elements throughout the description.

[0058] With particular reference to FIG. 1, there is provided a vehicle 1 with an internal combustion engine 100 provided with a crankcase ventilation system according to the present invention. The vehicle 1 depicted in FIG. 1 is a truck for which the inventive internal combustion engine 100 and crankcase ventilation system, which will be described in detail below, is particularly suitable for.

[0059] Turning, to FIG. 2, which illustrates an engine system according to an example embodiment of the present invention. The engine system comprises a fuel system 201. The fuel system 201 may contain any fuel that is suitable for the specific engine type. Hence, the fuel system 201 may comprise diesel, petrol, ethanol, dimethyl ether (DME), etc. The invention should thus not be limited to any specific type of fuel propelling the engine. Further, the engine system comprises a cylinder arrangement 202 having a crankcase 217 housing a crank axle connected to a plurality of pistons via respective connecting rods. Fuel from the fuel tank 201 is guided to the engine via an oil trap 214. According to an example and as depicted in FIG. 2, an additional oil trap 215 may be positioned between the oil trap 214 and the fuel tank 20.

[0060] Moreover, the engine system comprises a crankcase ventilation system 206, which will be described in detail below, and a turbo unit comprising a turbine and a compressor. More specifically, a conduit 209 connects the crankcase ventilation system 206 to an intake 203 of the internal combustion engine, and further through an inlet and into the internal combustion engine.

[0061] Now, reference is made to the crankcase ventilation system 206 of the present invention which is illustrated in FIG. 2. The crankcase ventilation system 206 comprises, according to the non-limiting example depicted in FIG. 2, an oil mist separator 204, a relief valve 208, a valve 210 electrically connected to a control unit 211, and an optional by-pass valve 216. The oil mist separator 204 is connected to a blow-by path 205 and arranged downstream of the crankcase. The relief valve 208 is further arranged downstream the oil mist separator 204 in fluid communication with the oil mist separator 204 and an ambient environment of the internal combustion engine. The relief valve 208 should be interpreted as a valve which is positioned in an open state when it is exposed to a pressure exceeding a predefined pressure limit. Also, the valve 210 is arranged downstream the oil mist separator 204 and arranged in fluid communication with the oil mist separator and the intake 203 of the internal combustion engine. Finally, the optionally arranged by-pass valve 216 is positioned downstream the valve 210 and in fluid communication with the valve 20 and the intake 203 of the internal combustion engine.

[0062] Furthermore, the valve 210 may be a controllable valve, which is positioned in an open state or a closed state by means of a signal from the control unit 211. The controllable valve may, for example, be a two-way valve.

[0063] The following will now describe the function of the crankcase ventilation system 206, and the associated method, in further detail. Reference is thus made to FIGS. 2-4.

[0064] When there is fluid leakage formed in the crankcase 217 from e.g. the combustion process of the internal combustion engine, this crankcase fluid leakage is directed out from the crankcase through the blow-by path 205 and directed into the oil mist separator 204. In the oil mist separator 204 the leaked crankcase fluid is provided to a separation process such that the fluid leaving the oil mist separator 204 is free, or relatively free, from particles that may negatively affect the environment. Hence, the fluid leaving the oil mist separator 204 into the conduit 207 is relatively clean. The leaked crankcase fluid may thereafter be guided to either the valve 210 or to the relief valve 208.

[0065] In order to determine if the leaked crankcase fluid is to be guided through the valve 210 or through the relief valve 208, the invention determines if the internal combustion engine is operating according to a normal mode of operation or to an abnormal mode of operation. This determination is illustrated in FIG. 3 where an example relating to the exhaust temperature 302 over time 304 is given. Hence, FIG. 3 illustrates the exhaust temperature variation over time when the vehicle is running. It should be noted that the depicted graph in FIG. 3 only serves for illustrative purposes.

[0066] The solid line 306 in FIG. 3 illustrates the preset parameter range 306 over time 304, in the illustrated embodiment the expected exhaust temperature variation over time according to a specific operating condition. The depicted solid line illustrates a specific temperature value for each point in time, but it should be readily understood that this preset value have some tolerances thus providing a temperature range for each point in time, i.e. a maximum and a minimum temperature value for each poinT in time. Accordingly, the preset parameter range 306 in FIG. 3 illustrates an expected exhaust temperature, based on the specific driving condition of the vehicle. Hence, the preset parameter range 306 defines the temperature range of the expected exhaust temperature under a normal operating mode.

[0067] The dotted line 308 in FIG. 3 illustrates the measured parameter value 308, in the example a measured exhaust temperature at different points in time. The measured temperature 308 is below the expected temperature 306 during almost the entire time period illustrated in FIG. 3. However, at a specific point in time, the measured temperature 308 is increased in relation to the expected temperature 306. The difference 30 between the measured temperature 308 and the expected temperature 306 is measured. Hereby, if the difference 30 between the measured temperature 308 and the expected temperature 306 is larger than a threshold temperature value, it is determined that the internal combustion engine is not exhibiting a normal mode of operation, i.e. the internal combustion engine is exhibiting an abnormal mode of operation. The determination that the internal combustion engine is exhibiting an abnormal mode of operation may also, instead of comparing the difference 30 to a threshold, be based on the fact that the measured temperature is higher than an upper end value of the temperature range. Hence, it suffices that the temperature is higher than expected to determine that the internal combustion engine is exhibiting an abnormal mode of operation.

[0068] Although FIG. 3 is depicted and described in relation to the exhaust temperature, other parameters are of cause also valid for determining if the internal combustion engine is exhibiting normal or abnormal mode of operation, such as crankcase pressure, engine speed, etc. These parameters may be measured and compared individually or in combination with each other.

[0069] When it is determined that the measured exhaust temperature is larger than normal, i.e. the difference 30 between the measured exhaust temperature 308 and the expected exhaust temperature 306 is larger than the preset threshold temperature value, it is determined that the crankcase is not exhibiting a normal mode of operation. Accordingly, the internal combustion engine exhibits an abnormal mode of operation. Hereby, and referring back to FIG. 2, the control unit 211 provides a signal to the valve 210 such that the valve 210 is arranged in a closed state which does not allow leaked crankcase fluid from the crankcase 217 to pass through the valve 210. The leaked crankcase fluid will then instead be guided to the relief valve 208. The relief valve 208 is in a normally closed state meaning that in its normal state it does not allow leaked crankcase fluid to pass there through. However, when the valve 210 is closed, the relief valve 208 will be exposed to increased pressure due to the pressure from the leaked crankcase fluid. When the pressure on the relief valve 208 has exceeded a certain limit, the relief valve 208 will be arranged in an opened state, thereby guiding the leaked crankcase fluid through the relief valve 208 and to the ambient environment of the internal combustion engine 100.

[0070] Reference is finally made to FIG. 4 which illustrates a flow chart of the method according to an example embodiment of the present invention. According to a first step of the method, an operation parameter value is measured S1. Hereby, a value of a parameter of the internal combustion engine is measured. Since it is clear from the inventive concept of the present application that the parameter value is measured when the engine is running, the parameter value may be continuously measured during operation of the internal combustion engine. Thereafter, the measured S1 parameter value 308 is compared S2 with a preset parameter range. The preset parameter range 306 is a range for the same parameter that was measured in the previous step and is a range that defines a mode of operation of the internal combustion engine. Accordingly, the preset parameter range 306 is dependent on the specific operation of the vehicle and defines a mode of operation based on this specific operation of the vehicle. For example, the preset temperature range 306 described and depicted above in the example embodiment in relation to FIG. 3 can have different proportions/temperature values if the vehicle is running upwards in a steep hill compared to driving the vehicle on a straight and level road.

[0071] Thereafter, it is determined S3 if the internal combustion engine is in the mode of operation. This determination is made by comparing the measured parameter value 308 with the preset parameter range 306. Referring again to the example depicted in FIG. 3, the compared difference 30 between the measured temperature 308 and the preset parameter range 306, i.e. the expected exhaust temperature range, is at a point in time higher than a predetermined threshold value. At this depicted point in time, it is determined that the internal combustion engine is not in the mode of operation, i.e. it is exhibiting an abnormal mode of operation.

[0072] The method is thereafter followed by the step of guiding S4 the leaked crankcase fluid from the crankcase 217 of the internal combustion engine 00 to the intake of the internal combustion engine if it is determined that the internal combustion engine is in the mode of operation. According to an example embodiment, the step of guiding the leaked crankcase fluid is executed by positioning the valve 210 in an open state such that leaked crankcase fluid can be guided from the crankcase 27, through the valve 210, and into the internal combustion engine 100.

[0073] However, if the internal combustion engine is not in the mode operation, leaked crankcase fluid is instead guided S5 to the ambient environment of the internal combustion engine. According to an example embodiment, this step is executed by closing the valve 210 such that leaked crankcase fluid is guided through the relief valve 208, which is forced to be positioned in an open state due to the pressure it is exposed to from the leaked crankcase fluid, and to the ambient environment of the internal combustion engine.

[0074] It should be noted that the invention works equally as well by switching position of the valve 210 and the relief valve 208. In such a case, the valve 210 should be positioned in the closed state to guide leaked crankcase fluid to the intake of the internal combustion engine via the relief valve 208, and in an open state to guide leaked crankcase fluid from the crankcase 217 to the ambient environment of the internal combustion engine 100.

[0075] According to a case where the valve 210, control unit 211 and by-pass valve 216 is removed from the above described crankcase ventilation system, i.e. the crankcase ventilation system only comprises the oil mist separator 204 and the relief valve 208. In such a case, leaked crankcase fluid is guided from the crankcase 217 to the intake 203 of the internal combustion engine 100 during normal mode of operation. However, in the case the conduit 209, for example, freeze due to low temperature where the vehicle is driving or is being clogged, such that leaked crankcase fluid is prevented from being guided all the way to the intake 203 of the internal combustion engine, the gas pressure in the conduit 209 will increase and when the pressure has exceeded a certain threshold value, the relief valve 208 will be positioned in an open state to guide leaked crankcase fluid there through. Hereby, the crankcase ventilation system will be transformed from a closed crankcase ventilation to an open crankcase ventilation system, such that the crankcase ventilation system is vented.

[0076] It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims. For example, the by-pass valve describe is not essential for the overall functioning of the crankcase ventilation system. Also, the crankcase ventilation system should not be construed as limited to the use of an oil mist separator. The invention functions equally well without the oil mist separator or with another component replacing the oil mist separator but providing a similar function to the system.