EP4684115A1

EP4684115A1 - Method for monitoring a crankcase ventilation system of a combustion engine

Info

Publication number: EP4684115A1
Application number: EP24775292.6A
Authority: EP
Inventors: Robert GRÖNING
Original assignee: Scania CV AB
Current assignee: Scania CV AB
Priority date: 2023-03-21
Filing date: 2024-03-12
Publication date: 2026-01-28
Also published as: CN120882959A; SE2350315A1; SE546435C2; WO2024196295A1

Abstract

The present application relates to a method for monitoring crankcase ventilation system (18) of a combustion engine (12), which crankcase ventilation system (18) comprises a conduit (20) between an engine crankcase (16) and an inlet (22) for combustion air, a first sensor arrangement (40) comprising a pressure sensor arranged at a first position in said air inlet (22), a second sensor arrangement (42) comprising a pressure sensor arranged at a first position in said conduit (20), and a flow restriction (44) configured to introduce a pre-determined pressure drop in said conduit (20) downstream of said second pressure sensor arrangement (42), the method comprising the steps of obtaining pressure data from said first and second pressure sensor arrangements (40, 42), calculating the flow of crankcase ventilation gases in said conduit (20) based on the pressure data and said flow restriction, and comparing said calculated flow with pre-obtained data regarding expected crankcase ventilation gas flows, wherein, if a calculated flow does not correspond to expected crankcase ventilation gas flows, determining that the crankcase ventilation system is mal-functioning and providing information that the crankcase ventilation system is mal-functioning.

Description

METHOD FOR MONITORING A CRANKCASE VENTILATION SYSTEM OF A COMBUSTION ENGINE

TECHNICAL AREA

The present application relates to crankcase ventilation systems for combustion engines and the monitoring of them in order to ascertain functionality.

BACKGROUND OF INVENTION

Combustion engines require ventilation of crankcases due to gases entering the crankcases from in particular the combustion chambers of the engines.

Conventionally, these gases have been emitted directly from the crankcase into the environment, possibly via oil traps that catch oil drops in the gases, so called open crankcase ventilation. In order reduce emissions from vehicles, so called closed crankcase ventilation systems have been developed. Most modern cars are equipped with such ventilation systems wherein a conduit, such as a hose and/or pipe, is provided between the crankcase and the combustion air inlet, usually adjacent the inlet air filter, thereby guiding the crankcase gases back into the combustion chamber.

These closed crankcase ventilation systems have not been mandatory for larger vehicles such as trucks, lorries, buses and construction vehicles. However, the EU and several countries have for many years successively increased the demands on reduced and/or cleaner emissions from heavy vehicles, and in line with that, new legislation suggests that all non-treated gases from vehicles with combustion engines are prohibited to be let out into the atmosphere, and this includes crankcase gases, which means that these vehicles probably will be required to be equipped with closed crankcase ventilation systems.

A drawback with closed crankcase ventilation systems is that they affect the combustion engines in several negative ways. Even though oil traps are provided in these closed systems, some fine oil drops, or mist, will pass the oil traps and enter the air intake duct. These drops or mist will then mix with the combustion inlet air and be sucked into the air intake, where very often a compressor or a turbo charger as well as an inter-cooler are arranged, whereby the oil will deposit on the air intake duct as well as the compressor and intercooler, forming sticky layers on the surfaces. These deposits will eventually reduce the efficiency of the components and also shorten the life of these components and even the engine itself.

Because of this problem of reduced life for many components of the combustion engine as well as the engine itself, there is a pronounced risk that the vehicle owner will try to tamper with and manipulate the closed crankcase ventilation system by removing the communication between the crankcase and the air inlet, such as simply disconnecting the crankcase ventilation conduit at some point along the length of the conduit.

This behaviour will probably constitute a delict when new legislation is in force, but it may be a very hard task for authorities to detect such tampering, considering the very large number of heavy vehicles operating daily, for example throughout Europe when looking at the transportation sector only. Measures are then needed for detecting such tampering in a reliable and direct way without the need for large numbers of inspectors or policemen checking the vehicles. Moreover, there might also be the case that the crankcase ventilation system has a fault that is not a result of tampering, and those cases are also a concern that need to be detected and handled in an appropriate way.

BRIEF DESCRIPTION OF INVENTION

The aim of the present application is to provide improved measures for monitoring crankcase ventilation systems. This aim is solved with the features of the independent patent claim. Preferable embodiments form the subject of the dependent patent claims.

According to the application, a method for monitoring crankcase ventilation system of a combustion engine is provided. The crankcase ventilation system may comprise a conduit between an engine crankcase and an inlet for combustion air, a first sensor arrangement comprising a pressure sensor arranged at a first position in said air inlet, a second sensor arrangement comprising a pressure sensor arranged at a first position in said conduit, and a flow restriction configured to introduce a pre- determined pressure drop in said conduit downstream of the second pressure sensor arrangement.

The method may comprise the steps of obtaining pressure data from said first and second pressure sensor arrangements, calculating the flow of crankcase ventilation gases in said conduit based on the pressure data and the flow restriction, and comparing the calculated flow with pre-obtained data regarding expected crankcase ventilation gas flows, wherein, if a calculated flow does not correspond to expected crankcase ventilation gas flows, determining that the crankcase ventilation system is mal-functioning and providing information that the crankcase ventilation system is mal-functioning.

With this solution, any mal-functions of the crankcase ventilation system may be detected. This may be the case if there is a leakage in the crankcase ventilation system due for instance to breakage or disconnection of conduits of the system. Regarding disconnection, the method will detect any tampering with the crankcase ventilation system, such as purposely altering the closed system to an open system.

According to a further aspect, wherein the second sensor arrangement is a pressure and temperature sensor, the method may comprise the further steps of obtaining temperature data from the second sensor arrangement, comparing the obtained temperature data with pre-obtained data regarding expected temperatures in the crankcase ventilation gas flows, wherein, if the obtained temperature data does not correspond to the pre-obtained data, determining that the crankcase ventilation system is mal-functioning and providing information that the crankcase ventilation system is mal-functioning.

With this solution, as an alternative, and for leakage along certain locations along the conduit of the crankcase ventilation system, which may be hard to detect using the pressure measurements discussed above, the temperature of the crankcase gases may be used to obtain information indicating that there is a leakage and that the crankcase ventilation system is mal-functioning. In this regard, the crankcase ventilation system may further comprise a pressure control valve provided upstream of said second sensor arrangement, wherein the method further comprises, if the calculated flow does not correspond to expected crankcase ventilation gas flows, determining that the crankcase ventilation system is mal-functioning downstream of the pressure control valve, and wherein, if said obtained temperature data does not correspond to the pre-obtained data, determining that the crankcase ventilation system is mal-functioning upstream of said pressure control valve and, when determined, providing information that the crankcase ventilation system is mal-functioning.

This provides the possibility to use both pressure and temperature in the crankcase ventilation system in order to detect leakage in all locations along the conduit of the crankcase ventilation system. This is an advantage since the function of the pressure control valve is to try to maintain a more or less constant pressure in the crankcase ventilation system, and particularly at the second sensor arrangement which may result in that a leakage is not detected by the analysis of the measured pressure. The leakage may then instead be detected in that the temperature measured deviates due to that no crankcase ventilation gases are passing the second sensor arrangement.

The obtained information is preferably stored so that it may be used for analysing the crankcase ventilation system. For instance, the information may be used for alerting a driver of the vehicle. Further, the information may be obtained during service and/or repair of the vehicle. Service personnel may then check the crankcase ventilation system for leaks and/or manipulations. The information may further be transmitted to a cloud-based data storage and handling centre. It is also feasible that the information may trigger a control system of the vehicle to affect its functions, for instance reducing the power or speed of the vehicle, whereby a driver or user may be forced to correct the crankcase ventilation system if manipulated.

According to a further aspect, a controller may be provided, comprising program instructions which, when the program is executed by the controller, causes the controller to carry out the above method. The controller may be a part of an engine management system of the vehicle. Further, a vehicle may be provided, comprising a combustion engine. The engine is arranged with a crankcase ventilation system, which crankcase ventilation system comprises a conduit between an engine crankcase and an inlet for combustion air, a first sensor arrangement comprising a pressure sensor at a first position in the air inlet, a second sensor arrangement comprising a pressure sensor at a first position in the conduit, which first and second sensors are operably connected to a controller, a pre-determined flow restriction in the conduit downstream of the second sensor, and a controller for performing the above method.

The first sensor arrangement and/or the second sensor arrangement may further comprise a temperature sensor.

The vehicle may further comprise a pressure control valve arranged upstream of said second sensor arrangement.

These and other aspects of, and advantages with, the present invention will become apparent from the following detailed description of the invention and from the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

In the following detailed description of the invention, reference will be made to the accompanying drawings, of which

Fig. 1 is a schematic side view of a vehicle provided with the solution according to the application, and

Fig. 2 is a schematic view of a crankcase ventilation system comprising the solution according to the application.

DETAILED DESCRIPTION OF THE INVENTION

An example of a vehicle 10 provided with a solution according to the application is shown in Fig. 1. The vehicle 10 comprises a combustion engine 12, known per se and will not be described in detail. The vehicle is provided with an engine management system 14 for controlling several functions, such as the engine and its components.

In order to function properly, the combustion engine 12 requires ventilation of gases of its crankcase 16, which gases mainly come from the combustion chambers 17 of the engine. For large diesel engines, the amounts of gases entering the crankcase can be quite considerable, normally in the region of 50 - 200 l/min and increasing with worn engines. Thus, the gases from the crankcase need to be handled in an efficient way.

The crankcase 16 is thus provided with a crankcase ventilation system 18, Fig. 2, comprising a conduit 20 in the form of a pipe or hose or any other suitable conduit. The conduit 20 may be connected to an air inlet 22 for the combustion engine, for instance between an air filter 24 and a turbo compressor 26 as seen in Fig. 2. Between the crankcase 16 and the air inlet 22, several components are provided for controlling the flow of crankcase gases. Closest to the crankcase 16, an oil mist separator 28 is provided for separating oil mist from the crankcase gases, that may comprise a restricted area or impactor 30, together with a fan 32, for providing a certain controlled pressure in the conduit 20. A pressure sensor 33 is also provided for controlling the pressure. The fan 32 and the pressure sensor 33 are operably connected to a controller 34 that may be a part of the engine management system 14.

Downstream of the oil mist separator 28, a filter 36 may be arranged for further handling oil mist that might have passed the oil mist separator 28. Further, a pressure control valve 38, or PCV, is provided in the system. The function of the PCV 38 is to maintain a relatively constant pressure in the crankcase ventilation system 18. A first sensor arrangement 40 comprising a pressure sensor, is moreover provided at a first position in the air inlet 22. The first position may be between the air filter 24 and the intake to the compressor or turbo 26. The first sensor arrangement 40 may furthermore comprise a temperature sensor. The first sensor arrangement may in this case either comprise two separate sensors, i.e. a pressure sensor and a temperature sensor, or two sensors integrated into one sensor capable of measuring both pressure and temperature. According to the application, a second sensor arrangement 42 comprising a pressure sensor is provided at a first position in the conduit 20. The first position may be downstream of the PCV 38 and upstream of the air inlet 22. The second sensor arrangement 42 may further comprise a temperature sensor, as will be explained in more detail below. The second sensor arrangement may in this case either comprise two separate sensors, i.e. a pressure sensor and a temperature sensor, or two sensors integrated into one sensor capable of measuring both pressure and temperature.. The first and the second sensor arrangements 40, 42 may be of the same type, but may also be of different type. In this regard, it is of course possible to use two separate sensors instead of one combined sensor. Further, a flow restriction 44 is provided downstream of the second sensor arrangement 42 configured to introduce a pre-determined pressure drop in the conduit 20. The flow restriction 44 may not be large, but should be well defined.

A method according to the application is intended to function as follows. When the combustion engine 12 is operating, gases from the crankcase 16 will stream through the crankcase ventilation system 18 and enter into the air inlet 22 where they will mix with fresh air and be used in the combustion process. The volume of crankcase gases per time unit is relatively well known and may vary within a range depending on the engine speed and the load on the engine. The age of the engine may also be a factor that affects the gas volumes to some extent. However, the amounts are known.

The pressure of the crankcase gases flowing past the second sensor arrangement 42 is measured as well as the pressure of the gases in the air inlet by the first sensor arrangement 40. Together with the known flow restriction 44, the data from the two pressure sensors will provide a flow measurement. This flow measurement is compared with the known and pre-obtained range of crankcase gas flow that a combustion engine is emitting. As long as the flow obtained with the help of the sensors is within what is expected, then no further measures are taken.

Should however gases escape out of the crankcase ventilation system 18 downstream of the PCV 38, the measured pressures will alter considerably. This is in particular the case if the crankcase ventilation system 18 is manipulated such that an open crankcase ventilation is obtained, such as disconnecting a crankcase ventilation conduit, either at the outlet from the PCV 38 or at the inlet to the air inlet 22, and possibly also by blocking the passage to the air inlet 22. The altered pressures will provide a determination and thus information that the crankcase ventilation system 18 is malfunctioning.

Should gases escape out of the crankcase ventilation system 18 upstream of the PCV 38, for example if the conduit 20 is disconnected between the crankcase 16 and the oil mist separator 28, the measured pressures might not alter considerably as with the above scenario. This is due to the function of the PCV 38, trying to maintain a more or less constant pressure between the oil mist separator 28 and the PCV 38. In order to handle that, temperature measurement of the second sensor arrangement 42 is used. The temperature of the crankcase gases is relatively stable, varying somewhat with engine speed and engine load, but within a moderate range and with very low temperature fluctuations. Should then for instance a conduit of the crankcase ventilation system 18 between the crankcase 16 and the PCV 38 be disconnected, then the temperature measured by the second sensor arrangement 42 will differ considerably from expected, this situation determining a mal-function of the crankcase ventilation system 18 and providing information thereof.

Another scenario is if gases escape out of the crankcase ventilation system 18 upstream of the PCV 38but downstream of the second sensor arrangement 42, for instance if the conduit is disconnected between the oil mist separator 28 and the filter 36 or the PCV 38. In this case, the pressure measured will clearly deviate, and in particular if the inlet to the filter or PCV is blocked, leading to no flow of crankcase gases past the second sensor arrangement 42.

The components of the crankcase ventilation system 18 and in particular the first and the second sensor arrangements 40, 42, are connected to a controller 34 of the vehicle, such as comprised in an engine management system 14. The controller 34 is provided with processor capacity, memory means and I/O functionality. The controller 34 is provided with computer program code and instructions to perform the above mentioned operation. The computer program is usually constituted by a computer program product that performs the operation that is stored on a non-transitory/non- volatile digital storage medium.

The controller 34 obtains data from the sensors, processes the data and compares data with stored data regarding crankcase gas flows and temperatures. If an anomality regarding obtained flows and/or temperatures is detected and determined, this information is stored and can be retrieved. This may for example be during service of the vehicle or at an inspection, such as an annular vehicle inspection. Further, a fault indication may also be provided to the driver on the dashboard. It might also be possible to affect the functions of the vehicle, such as limiting the output power and/or speed of the engine so as to force the owner/user of the vehicle to handle the fault in order to have the vehicle fully operational again. As further measures, it is feasible that data stored in the controller is transmitted to a cloudbased information storage centre via suitable wireless communication means provided in the vehicle.

It is to be understood that the embodiment described above and shown in the drawings is to be regarded only as non-limiting examples that can be modified in many ways within the scope of the patent claims.

Claims

PATENT CLAIMS

1 . A method for monitoring crankcase ventilation system (18) of a combustion engine (12), which crankcase ventilation system (18) comprises a conduit (20) between an engine crankcase (16) and an inlet (22) for combustion air, a first sensor arrangement (40) comprising a pressure sensor arranged at a first position in said air inlet (22), a second sensor arrangement (42) comprising a pressure sensor arranged at a first position in said conduit (20), and a flow restriction (44) configured to introduce a pre-determined pressure drop in said conduit (20) downstream of said second pressure sensor arrangement (42), the method comprising the steps of:

- obtaining pressure data from said first and second pressure sensor arrangements (40, 42),

- calculating the flow of crankcase ventilation gases in said conduit (20) based on the pressure data and said flow restriction, and

- comparing said calculated flow with pre-obtained data regarding expected crankcase ventilation gas flows, wherein, if a calculated flow does not correspond to expected crankcase ventilation gas flows, determining that the crankcase ventilation system is mal-functioning and providing information that the crankcase ventilation system is mal-functioning.

2. A method according to claim 1 , wherein said second sensor arrangement (42) further comprises a temperature sensor, wherein the method comprises the further steps of:

- obtaining temperature data from said second sensor arrangement (42),

- comparing the obtained temperature data with pre-obtained data regarding expected temperatures in said crankcase ventilation gas flows, wherein, if said obtained temperature data does not correspond to the pre-obtained data, determining that the crankcase ventilation system (18) is mal-functioning and providing information that the crankcase ventilation system (18) is malfunctioning.

3. A method according to claim 2, wherein said crankcase ventilation system (18) further comprises a pressure control valve (38) provided upstream of said second sensor arrangement (42), wherein, if calculated flow does not correspond to expected crankcase ventilation gas flows, determining that the crankcase ventilation system (18) is mal-functioning downstream of said pressure control valve (38), and wherein, if said obtained temperature data does not correspond to and the pre-obtained data, determining that the crankcase ventilation system is mal-functioning upstream of said pressure control valve (38) and, when determined, providing information that the crankcase ventilation system (18) is mal-functioning.

4. A method according to any of the preceding claims, wherein said information is stored.

5. A method according to claim 4, wherein said information is used for alerting a driver of the vehicle.

6. A method according to claim 4 or 5, wherein said information can be obtained during service and/or repair of the vehicle.

7. A method according to any of the claims 4 to 6, wherein said information is transmitted to a cloud-based data storage and handling centre.

8. A method according to any of the claims 4 to 7, wherein said information triggers a control system of the vehicle to affect its functions.

9. A controller (34) comprising program instructions which, when the program is executed by the controller (34), causes the controller (34) to carry out the method according to claims 1 - 8.

10. A computer-readable storage medium comprising program instructions which, when executed by a controller (34), cause the controller (34) to carry out the method according to claims 1 - 8.

11. A vehicle (10) provided with a combustion engine (12), the combustion engine

(12) being arranged with a crankcase ventilation system (18), which crankcase ventilation system (18) comprises a conduit (20) between an engine crankcase (16) and an inlet (22) for combustion air, a first sensor arrangement (40) comprising a pressure sensor at a first position in said air inlet, a second sensor arrangement (42) comprising a pressure sensor at a first position in the conduit, which first and second sensor arrangements (40, 42) are operably connected to a controller (34), a pre-determined flow restriction (44) in said conduit downstream of said second sensor arrangement (42), and a controller (34) according to claim 9. 12. A vehicle (10) according to claim 11 , wherein the first sensor arrangement (40) and/or the second sensor arrangement (42) further comprises a temperature sensor.

13. A vehicle (10) according to any one of claims 11-12, wherein a pressure control valve (38) is arranged upstream of said second sensor arrangement