Method for diagnosing a part of a crank case ventilation system

Abstract

A method for diagnosing a part of a crank case ventilation system of an engine operable in different engine running conditions, the system comprising an electrically driven crank case ventilation, eCCV, separator. The method comprises determining a compared power consumption of the eCCV separator by comparing a current power consumption indicative value of the eCCV separator with a reference value; determining whether or not the compared power consumption achieved as pre-set criteria; and diagnosing a fault in the system in response to determining that the compared power consumption achieves the pre-set criteria.

Claims

1. A method for diagnosing a part of a crank case ventilation system of an engine operable in different engine running conditions, the system comprising an electrically driven crank case ventilation (eCCV) separator, configured for receiving blow-by gases from a crankcase of the engine, and configured for discharging cleaned gases back to the engine or to the atmosphere, the method comprising: determining a compared power consumption of the eCCV separator by comparing a current power consumption indicative value of the eCCV separator with a reference value; wherein the current power consumption indicative value is based on a power consumption value of the eCCV separator at the current engine running condition, or is based on a difference between a power consumption value of the eCCV separator at the current engine running condition and a power consumption value of the eCCV separator at a different engine running condition; determining whether or not the compared power consumption achieves a pre-set criteria; and diagnosing a fault in the system related to a problem in receiving blow-by gases to the eCCV separator and/or discharging cleaned gases from the eCCV separator, in response to determining that the compared power consumption achieves the pre-set criteria.

2. The method according to claim 1, wherein the current power consumption indicative value is the power consumption value of the eCCV separator at the current engine running condition, and the reference value is an expected power consumption of the eCCV separator at the same engine running condition.

3. The method according to claim 1, wherein the current power consumption indicative value is based on a difference between a power consumption value of the eCCV separator at the current engine running condition and a power consumption value of the eCCV separator at a different engine running condition, and wherein the reference value is based on a difference between corresponding expected power consumption of the eCCV separator.

4. The method according to claim 1, wherein the fault in the system is related to a fault in the eCCV separator and/or a fault in a gas connection to and/or from the eCCV separator.

5. The method according to claim 1, wherein the fault is related to a broken, at least partly blocked or disconnected hose or pipe arranged to transport blow-by gases from the crankcase of the engine to the eCCV separator, and/or arranged to transport cleaned gases from the eCCV separator to the engine or to the atmosphere.

6. The method according to claim 1, wherein the fault is related to the eCCV separator being stuck.

7. The method according to claim 1, wherein the current power consumption indicative value is a feedback signal from the eCCV separator, or is provided by an electrical control unit arranged and configured to control the operation of the eCCV.

8. The method according to claim 1, wherein the current power consumption indicative value is not based on an external sensor.

9. A controlling apparatus for diagnosing a part of a crank case ventilation system of an engine operable in different engine running conditions, the crank case ventilation system comprising an electrically driven crank case ventilation (eCCV) separator, configured for receiving blow-by gases from a crankcase of the engine, and configured for discharging cleaned gases back to the engine or to the atmosphere, the controlling apparatus being configured to: determine a compared power consumption by comparing a current power consumption indicative value with a reference value, wherein the current power consumption indicative value is based on a power consumption value of the eCCV separator at the current engine running condition, or is based on a difference between a power consumption value of the eCCV separator at the current engine running condition and a power consumption value of the eCCV separator at a different engine running condition; determine whether or not the compared power consumption achieves a pre-set criteria; and diagnose a fault in the system related to a problem in receiving blow-by gases to the eCCV separator and/or discharging cleaned gases from the eCCV separator in response to determining that the compared power consumption achieves the pre-set criteria.

10. A crank case ventilation system of an engine operable in different engine running conditions, the system comprising an electrically driven crank case ventilation, eCCV, separator and a controlling apparatus according to claim 9.

11. The crank case ventilation system according to claim 10, further comprising a first hose or pipe arranged and configured to transport blow-by gases from a crankcase of the engine to the eCCV separator, and a second hose or pipe arranged and configured to discharge cleaned gases from the eCCV separator back to the engine or to the atmosphere, wherein the controlling apparatus is configured to detect a fault related to a broken, at least partly blocked or disconnected first hose or pipe and/or second hose or pipe.

12. The crank case ventilation system according to claim 10, wherein the controlling apparatus is configured to detect a fault related to the eCCV separator being stuck.

13. A vehicle comprising a controlling apparatus according to claim 9.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) 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

(2) FIG. 1 is a side view of a vehicle comprising an internal combustion engine and a crankcase ventilation system according to an example embodiment of the present invention;

(3) FIG. 2 is a schematic view of a combustion engine and crankcase ventilation system according to an example embodiment of the present invention;

(4) FIG. 3 is a flow chart describing various steps of a method according to example embodiments of the invention; and

(5) FIGS. 4A-4B are graphs schematically relating the power consumption of the eCCV separator with the engine running condition.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

(6) With reference to FIG. 1 a vehicle 1, here embodied as a heavy duty truck 1 comprising an engine 20 and a crank case ventilation system 10 having a crank case ventilation separator 5 and controlling apparatus 3, is disclosed for which the crank case ventilation system 10 of a kind disclosed in the present disclosure is advantageous. However, the crank case ventilation system 10, i.e. at least the crank case ventilation separator 5 and the controlling apparatus 3, may as well be implemented in other types of vehicles, such as in busses, light-weight trucks, passenger cars, marine applications etc. The vehicle 1 of FIG. 1 may be a hybrid vehicle comprising an engine 20, being e.g. a diesel engine 20, and an electric machine. The diesel engine 20 is powered by diesel fuel, typically comprised in a fuel tank (not shown) and the electric machine is powered by electricity supplied from at least one energy storage or transformation device, e.g. a battery or a fuel cell.

(7) Turning to FIG. 2, which illustrate a crank case ventilation system 100 of an engine 200 operable in different engine running conditions according to an example embodiment of the present invention. The crank case ventilation system 100 may e.g. form the crank case ventilation system 10 shown in FIG. 1. The engine 200 of FIG. 2 is greatly simplified, and only the components of interest for the crank case ventilation system 100 are shown, i.e. a piston 203 reciprocally arranged inside a cylinder 205 to form a combustion chamber 207 in which gaseous fuel is combusted. The engine 200 further comprises a crankcase 210 housing the components of the engine 200. The different engine running conditions comprises e.g. idling and full-load operation of the engine 200.

(8) The crank case ventilation system 100 comprises an electric driven crank case ventilation separator 105, hereinafter abbreviated eCCV separator 105, a controlling apparatus 103 configured to control the operation of the eCCV separator 105, and a battery or other electricity source 107 for powering the eCCV separator 105. The eCCV separator 105 is arranged and configured to clean blow-by gases from the crankcase 210 of the engine 200. In more detail, blow-by gases are gases derived from the combustion chamber 207, which gases have leaked and passed the piston 203 and piston rings out to the crankcase 210. The blow-by gases are cleaned in the eCCV separator 105, typically by removing particles and oil droplet by centrifugal forces imposed by a separator member rotating with a certain speed (rpm). The removed particles and oil droplets may be returned to the engine 200 by a return line 115. The eCCV separator 105 is driven by electricity from the electricity source 107, and the power consumption of the eCCV separator 105 depends mainly on the combination of separation capacity (related to e.g. the speed of the separator, or rotatable separator member) and the amount of blow-by gases handled (related to e.g. the flow of blow-by gases through the eCCV separator 105). The power consumption of the eCCV separator 105 may be controlled and monitored by the controlling apparatus 103, e.g. by communication line 104. Alternatively, the power consumption of the eCCV separator 105 may be provided as a feedback signal from the eCCV separator 105. It should be noted that the controlling apparatus 103 may be, or be comprised in, an electrical control unit of the vehicle, and thus the power consumption of the eCCV separator 105 may considered to be provided by the electrical control unit 103 arranged and configured to control the operation of the eCCV separator 105.

(9) The crank case ventilation system 100 comprises a first hose 110 for transporting blow-by gases from the crankcase 210 to the eCCV separator 105, and a second hose 120 for transporting clean gases from the eCCV separator 105 back to the engine 200, and the combustion chamber 207. Thus, the eCCV separator 105 is configured to receive blow-by gases from the crankcase 210 via the first hose 110, and is configured to discharge cleaned gases back to the engine 200 via the second hose 120. It should be noted that the first hose 110 and/or the second hose 120 may instead of hoses be pipes or any other line for transporting gases, such as channels. For example, the eCCV separator 105 may be arranged on the crankcase 210, and blow-by gases may be transported from the crankcase 210 to the eCCV separator 105 simply by channel or an opening or orifice in the crankcase 210. As indicated in FIG. 2, the second hose 120 may transport the cleaned gases to an intermediate component 130, e.g. being part of the air intake to the engine 200. As an alternative, instead of transporting blow-by gases back to the engine 200, the second hose 120 may simply release the cleaned gases to the atmosphere. As a further alternative, instead of using the second hose 120 to release the cleaned gases to the atmosphere, the eCCV separator 105 may simply comprise an orifice or opening 109 releasing the cleaned gases to the atmosphere.

(10) A method of diagnosing at least a part of the crank case ventilation system 100 will now be described with reference to the flow chart in FIG. 3, with additional reference to the crank case ventilation system 100 and engine 200 of FIG. 2.

(11) In a step S10, being e.g. a first step S10, a compared power consumption of the eCCV separator 105 is determined by comparing a current power consumption indicative value of the eCCV separator 105 with a reference value.

(12) In FIG. 2, the current power consumption indicative value is typically determined by monitoring the power consumption of the eCCV separator 105 by the controlling apparatus 103, and potentially the communication line 104 to the electricity source 107. Thus, the current power consumption indicative value may be referred to as a monitored power consumption indicative value, or monitored current power consumption indicative value. A power consumption indicative value may e.g. be current and voltage based signals received from the eCCV separator 105 or electricity source 107, the current and voltage being used to determine the power consumption.

(13) In a step S20, being e.g. a second step S20, it is determined whether or not the compared power consumption achieved as pre-set criteria.

(14) For example, the pre-set criteria is based on a relation between the compared power consumption and a threshold value, e.g. that the compared power consumption is lower than a threshold value.

(15) In a step S30, being e.g. a third step S30, a fault in the system is diagnosed in response to determining that the compared power consumption achieves the pre-set criteria.

(16) That is, according to the example of relating the compared power consumption with a threshold value, if the compared power consumption is lower than the threshold value, a fault is diagnosed.

(17) The steps of the method described with reference to the flow chart of FIG. 3 may e.g. be included in the controlling apparatus 103 of the system 100 of FIG. 2. Thus, the controlling apparatus 103 is configured to: determine a compared power consumption by comparing a current power consumption indicative value (as e.g. a current power consumption in the unit J/s or W) with a reference value, corresponding to the S10; determine whether or not the compared power consumption achieved as pre-set criteria, corresponding to the step S20; and diagnose a fault in the system in response to determining that the compared power consumption achieves the pre-set criteria, corresponding to the step S30.

(18) Turning to FIG. 4A showing a graph schematically relating the power consumption of the eCCV separator 105 on the Y-axis with the engine running condition on the X-axis. The curve C1 represents a function of how the power consumption relates to the engine running condition in a ramping from idling, X1, to full load, X2, in a crank case ventilation system 100 operating with no faults. That is, the curve C1 may be referred to as a reference curve C1 comprised of a plurality of reference values, each reference value representing the case ventilation system 100 operating with no faults at an associated engine running condition. Moreover, in FIG. 4A a monitored value of the current power consumption of the eCCV separator 105 is marked with a diamond D. That is, D represents the current power consumption determined by e.g. a current power consumption indicative value, such as the current and voltage of the eCCV separator 105. As seen in FIG. 4A, the current power consumption D is for an operation of the engine 200 in full load, i.e. for engine running condition X2, and differs from the reference value determined by the reference curve C1 at the same engine running condition X2, by a difference Z. Thus, by relating the value difference Z with what is acceptable for the system 100 and current engine running condition, e.g. taking into account tolerances and measurement errors, a fault in the system 100 can be diagnosed. For example, by applying the pre-set criteria of comparing if the value difference Z is larger than a threshold value Z1, a fault in the system 100 can be determined if the value difference Z is larger than the threshold value Z1. The threshold value Z1 is typically related to the specific system 100 and eCCV separator 105, as well as the current engine running condition.

(19) It should be noted, that the monitored value of the current power consumption D may be based on a power consumption indicative value, the power consumption indicative value may have a unit different to the unit of power consumption (J/s, W), but still representing the power consumption of the eCCV separator 105. In such case, the reference curve C1 is comprised of reference values in corresponding unit.

(20) In FIG. 4A, the current power consumption D is based on a power consumption value, typically in the unit J/s or W, of the eCCV separator 105 at the current engine running condition X2, and the reference value (comprised in the reference curve C1) is based on a power consumption value, typically in the unit J/s or W, being an expected power consumption of the eCCV separator at the same engine running condition X2, with no faults in the system 100. For example, the reference curve C1 may be made during a start-up of the system 100, subsequent to a fault check verifying that the system 100 is operating with no faults.

(21) As an alternative to the criteria described with reference to FIG. 4A, the current power consumption may be based on a difference between a power consumption value of the eCCV separator 105 at the current engine running condition X2 and a power consumption value of the eCCV separator at a different engine running condition, e.g. idling X1, as shown by the marker diamond D′ in the graph of FIG. 4B. Correspondingly, the reference value, or reference curve, may be based on a difference between corresponding expected power consumption of the eCCV separator 105. Thus, a normalized reference curve C1′ may be used to for the compared power consumption of the eCCV separator 105, as can be shown in the graph of FIG. 4B. In other word, the normalized reference curve C1′ in FIG. 4B has been normalized with regards to the engine running condition of idling X1. Thus, a corresponding value difference Z′ and applicable pre-set criteria may be established as described for FIG. 4A.

(22) As the power consumption of the eCCV separator 105 depends mainly on the combination of separation capacity (related to e.g. the speed of the separator, or rotatable separator member) and the amount of handled blow-by gases (related to e.g. the flow of blow-by gases through the eCCV separator 105), fault in the system relating to a reduction in the flow of gases through the eCCV separator 105 may be diagnosed by the present method. For example, turning back to FIG. 2, the fault in the system 100 may be related to a fault in the eCCV separator 105 itself, e.g. a stuck separator or stuck separator member, resulting a loss of separation capacity. The fault may alternatively be related to a fault in the gas connection to and/or from the eCCV separator, as e.g. related to a problem in receiving blow-by gases to the eCCV separator 105 and/or discharging cleaned gases from the eCCV separator 105. In more detail, the fault may be related to a fault in the first hose 110, e.g. a broken, blocked or at least partly blocked or disconnected first hose 110, or a fault related to a fault in the second hose 120 e.g. a broken, blocked or at least partly blocked or disconnected second hose 120. As a further alternative, the fault may be related to a block, or at least partly blocked, orifice or opening 109 arranged and configured to release the cleaned gases to the atmosphere.

(23) 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. In particular, it should be understood that the crank case ventilation system 100 of FIG. 2 is schematic, and comprises the components emphasised in this disclosure. Other components, e.g. valves, throttles, pumps and compressors are typically included in the system 100 in positions known to the skilled person.

(24) Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed inventive concept, from a study of the drawings, the disclosure, and the appended claims. 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. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.