System with separator and pressure-actuated valve device

Abstract

The present disclosure relates to a system (100) comprising a centrifugal separator (110) for separating contaminants from a flow of gas from a crankcase of an internal combustion engine (10). A valve device (120) is arranged at an outlet of the separator, defining a flow path between the outlet and a conduit (130) for transporting the flow of gas away from the separator. A valve element (122) of the valve device forms a variable constriction of the flow path and is actuatable by a pressure differential between the flow path and an exterior of the valve device. The system also comprises a sensor (140) arranged to generate a signal indicative of a movement of the valve element, as well as a control unit (150) configured to determine an operational state of the valve device based on the signal.

Description

[0001] SYSTEM WITH SEPARATOR AND PRES SURE- ACTUATED VALVE DEVICE

[0002] Technical Field

[0003] The present invention pertains to the field of crankcase ventilation systems for internal combustion engines, and more specifically to systems for separating contaminants from a flow of crankcase gas.

[0004] Background

[0005] High-pressure gas in the combustion chambers of an internal combustion engine tends to leak past the piston rings into the engine’s crankcase. If not ventilated from the crankcase, the gas may cause a pressure increase that risks impeding the operation of the engine.

[0006] Typically, the gas contains contaminants such as unburned fuel, particulate matter, and traces of oil from the reservoir of oil held in the crankcase. Venting the gas directly into the atmosphere contributes to air pollution, which is harmful to the environment and poses a human health hazard.

[0007] To mitigate these issues, a crankcase ventilation system may be employed, comprising a centrifugal separator for separating oil and particulate matter from the gas before it is released to the environment or redirected back into the engine’s intake for reburning.

[0008] As the cleaning and recycling of the gas from the crankcase often plays a critical role in reducing emissions and maintaining engine health, it is desirable to monitor the operation of the separator and verify that the crankcase ventilation system has not been tampered with.

[0009] Summary

[0010] It is an object of the present disclosure to provide a technology that addresses at least some of the above concerns.

[0011] According to a first aspect, there is provided a system for separating contaminants from a flow of gas from a crankcase of an internal combustion engine. The system comprises a separator with a gas inlet and a gas outlet for guiding the flow of gas through the separator to allow at least some of the contaminants to be separated from the flow of gas. A valve device is arranged at the gas outlet and defines a flow path for connecting the gas outlet to a conduit transporting the flow of gas away from the separator. The valve device comprises a valve element forming a variable constriction of the flow path and being actuatable by a pressure differential between the flow path and an exterior of the valve device. The system further comprises a sensor arranged to generate a signal indicative of a movement of the valve element and a control unit configured to determine an operational state of the valve device based on the signal.

[0012] According to a second aspect, there is provided a method for determining a state of a centrifugal separator for separating contaminant from a flow of gas from a crankcase of an internal combustion engine. The method comprises: guiding the flow of gas through the separator to allow at least some of the contaminants to be separated from the flow of gas; transporting the flow of gas away from the separator through a flow path defined by a valve device; controlling, by means of a valve element of the valve device, a variable constriction of the flow path based on a pressure differential between the flow path and the exterior of the valve device; receiving, from a sensor, a signal indicative of a movement of the valve element; and determining the state of the centrifugal separator based on the signal.

[0013] The pressure differential between the flow path and the exterior of the valve device may be understood as a negative pressure within the flow path, i.e., a negative pressure relative to the ambient pressure. This negative pressure acts on the valve element, causing it to constrict the flow path. The negative pressure may be generated by a downstream component such as a turbocharger. However, it may also be attributed to the flow of cleaned crankcase gas passing the valve, which may induce a local pressure drop as explained by Bernoulli’s principle. Therefore, the valve device may be referred to as a pressure-actuated, or pressure-responsive valve device, operable to gradually constrict the flow path as the negative pressure increases in the flow path. By arranging the valve device at the gas outlet to connect the separator to the conduit transporting the flow of gas away from the separator, it is possible to limit negative pressures within the separator and thus the crankcase. This is of particular interest in cases where the separator is coupled to a downstream turbocharger that feeds the cleaned crankcase gas back into the engine for burning. As the turbocharger draws in the crankcase gas and compresses it for further routing to the engine’s intake, the turbocharger may effectively generate a negative pressure in the conduit from which it draws in the crankcase gas. If the pressure in the conduit becomes too low, it can lead to a reduced efficiency of the separator and various mechanical and operational issues of the engine. By constricting the flow path, excessive negative pressures can be avoided in the separator and crankcase.

[0014] The signal from the sensor, which comprises information about a movement or position of the valve element, makes it possible to determine an operational state of the valve device. This, in turn, allows for anomalies or deviations from expected behaviours of the valve device to be detected. Examples of such anomalies include inaction, sticking, and slow response times. By analysing the signal, it may be possible to determine whether the system is working as intended or if the separator or the valve device is malfunctioning. The malfunction may, for example, be caused by the separator being bypassed, the separator inlet being disconnected, or the output from the separator being released to the atmosphere instead of being fed to the turbocharger and returned to the combustion chamber.

[0015] The movement of the valve element may be compared with predetermined reference values to detect possible error states. The predetermined reference values may, for example, be associated with a normal or expected operation of the valve element (i.e., when the separator and the valve device work as intended) and may represent typical actuation patterns for a given operation point of the engine, i.e., the specific conditions under which the engine operates at a given moment. The operation point includes, for example, variables such as engine speed (RPM), load, fuel intake, and air mixture. An increasing load and speed may for example lead to an increased activity of the turbocharger, which in turn increases the pressure drop created by the turbocharger. It can therefore be expected that the valve element responds by constricting the flow passage to protect the separator from excessive pressure drops. If no such movement of the valve element is detected, this may indicate a malfunction state, in which the separator has been bypassed, disconnected, or otherwise tampered with.

[0016] The valve element may interact with a seat of the valve device to adjust the constriction of the flow passage. In an example, the valve element may be arrangeable in a first state in which the flow path is fully open and in a second state in which the flow path is fully constricted. In the fully constricted state, the valve element may abut against the seat to constrict the flow passage.

[0017] The fully constricted state may be understood as the maximum level of constriction allowed by the valve element and the seat. Some degree of flow in the flow path could still be permitted. This may be achieved by a leak structure allowing a leak flow between the valve element and the seat. The leak structure could, for example, include a slit or protrusion in the seat or the valve, ensuring the flow path is not completely closed in the fully constricted state. Beneficially, such a leak flow allows for crankcase gases to still pass through the separator and be cleaned by the same.

[0018] The valve element may be configured to switch from the first state to the second state in response to the pressure differential exceeding a predetermined threshold. The threshold may correspond to a ‘cracking pressure’ at which the valve device starts to constrict the flow path, i.e. More specifically, the valve element may start to move towards the seat to reduce the flow in the flow path.

[0019] The valve element may be of a so called ‘normally open’ type, which is arranged in the first state when not actuated. This may, for example, be achieved by means of an elastic element, such as a spring, pushing the valve element away from the seat to maintain the flow path fully open until the negative pressure reaches the above- mentioned threshold.

[0020] In some examples, the valve element comprises a membrane, or diaphragm. The membrane may be a flexible disc, for example formed of rubber or another elastomer. The membrane may be pushed away from the seat to maintain the flow path fully open (first state) or sucked towards the seat to constrict the flow path (second state) at certain negative pressures.

[0021] The sensor may be understood as a component producing signal indicative of a movement of the valve element, and more specifically presence or absence of a movement or a change in state of the valve element. In some examples, the signal may be used for a quantification of the movement. An alternate term for the sensor may therefore be ‘transducer’, including components that can sense or detect changes in the position of the valve element and thus the level of constriction of the flow path.

[0022] The sensor may be arranged on the separator itself, i.e. be provided on the centrifugal separator so that it together with the centrifugal separator form a single unit.

[0023] The sensor may be a position sensor that detects the position of the valve element. A position sensor may indicate the absolute position of the valve element (its location) or its relative position (displacement). As an example, the sensor may not be a pressure sensor.

[0024] In embodiments, the control unit is configured to determine a state of the centrifugal separator based on a signal from the sensor.

[0025] The sensor may be a mechanical sensor or optical sensor, arranged to measure a displacement or movement of the valve element. The sensor may be in direct physical contact with the valve element, employing one or more coils and a magnetic core moving in relation to each other as the valve element moves. Alternatively, the sensor comprises a potentiometer measuring a change in resistance as the position of a sliding or rotating contact moves in relation to a resistive element. Further examples of sensors include strain gauges measuring, in case of the valve element being a diaphragm, the strain as the diaphragm moves, and optical sensors using changes in light behaviour (such as intensity, phase, or wavelength) to measure movement.

[0026] In some examples, the control unit may be configured to determine a reference state associated with an operation point of the engine, compare the operational state of the valve device with the reference state, and determine, based on a deviation between the operational state and the reference state, a malfunction state of the centrifugal separator. As mentioned above, the operation point may include variables such as engine speed, load, and fuel intake. As the operation point affects the flow rate of the exhaust gases, which in turn drive the turbine wheel of the turbocharger, the operation point of the engine can be correlated to the negative pressure generated by the turbocharger. This, in turn, makes it possible to correlate the state of the valve device to the operation point of the engine. Or, in different words, to determine an expected movement or position of the valve element for a give operation point. Any deviations from the expected behaviour of the valve element may indicate a malfunction state, for example caused by the separator being disconnected or bypassed. Should such a malfunction state be determined, the control unit may generate an error signal.

[0027] The internal combustion engine, ICE, may typically be configured to propel a vehicle or a vessel, such as a lorry or a ship. The ICE may however also be a stationary engine, for instance driving an electric power generator.

[0028] By ‘separator’ is typically meant a centrifugal separator combining a plurality of separation members rotate by means of a rotor shaft to separate contaminants from the flow of gas. The rotor may be driven by a flow of pressurised oil, or by means of an electric motor. The plurality of separation members may typically be a stack of conical discs, and the separator may hence be considered to represent a disc stack centrifuge.

[0029] The terms ‘upstream’ and ‘downstream’ may be used to denote a direction or position as seen along a flow direction of the gas. Upstream may be understood as closer to a source of the flow and downstream as farther away from the source of the flow.

[0030] The term ‘flow path’, as used herein, denotes the route that crankcase gas takes through the separator and any downstream conduit during normal operation. The variable constriction formed by the valve device may be understood as a narrowing of the flow path to reduce the flow through the flow path.

[0031] Further features and advantages of the invention will become apparent from the following description of embodiments of the invention, given by way of example only, which is made with reference to the accompanying drawings.

[0032] Brief Description of the Drawings

[0033] Various aspects and examples of the present disclosure will be readily understood from the embodiments discussed in the following detailed description and the accompanying drawings, in which:

[0034] Figure l is a schematic representation of an engine and a crankcase ventilation system according to some examples.

[0035] Figure 2 shows a cross section of a centrifugal separation according to some examples, comprising a valve device with a valve element forming an adjustable constriction. Figures 3 A and 3B are flow charts outlining methods for determining a state of a centrifugal separator according to some examples.

[0036] Detailed Description

[0037] Figure 1 is a schematic illustration of an internal combustion engine (ICE) 10, which typically operates by combusting a fuel-air mixture within a cylinder to generate a high- pressure gas that causes a piston to move in a reciprocating movement. The reciprocating movement is converted by a crankshaft 14 into a rotation motion that can be used to propel a vehicle or drive a generator, for example.

[0038] During the combustion process, some of the high-pressure gases and a small amount of the fuel-air mixture may leak past the piston rings into the crankcase 12. This crankcase gas, also referred to as ‘blow-by’ gas, needs to be ventilated from the crankcase 12 to not impede the operation of the engine 10. As the crankcase gas typically contains unbumt fuel, oil vapour, and combustion byproducts, it is desirable to subject the vented gas to a cleaning process.

[0039] Figure 1 shows an example of a crankcase ventilation system 100 in which the crankcase gas is guided from the crankcase 12 to a centrifugal separator 110 via an exhaust conduit 131. The separator 110 comprises a gas inlet 112 for receiving the flow of gas from the exhaust conduit 131 and a gas outlet 114 through which the cleaned flow of gas may be exhausted from the separator 110. The gas inlet 112 and the gas outlet 114 may thus be arranged to guide the flow of gas through the separator 110 to allow the separator 110 to remove contaminants such as oil and particulate matter from the crankcase gas. The cleaned crankcase gas may then be transported away from the separator 110 by a conduit 130 which, according to some examples, feeds the gas back into the engine’s 10 intake for re-burning. In the present example, this may be achieved by feeding the gas to a turbocharger 135. The separated oil may preferably be returned to the crankcase 12 via a return conduit 132.

[0040] A valve device 120 is arranged at the gas outlet 114. The valve device 120 defines a flow path connecting the gas outlet 114 to the conduit 130. The valve device 120 is arranged to constrict the flow path based on a pressure differential between the flow path and an exterior of the valve device 120, and more specifically to gradually constrict the flow path in response to an increasing negative pressure in the flow path. The variable constriction is controlled by a movable valve element, which may be arranged in a first state in which the flow path is fully open and in a second state in which the flow path is fully constricted. An example of such a valve device 120 is described in further detail in connection with figure 2.

[0041] The movement, or position, of the valve element may be measured by a sensor coupled to a control unit 150. By analysing the signal generated by the sensor, the control unit 150 may determine an operational state of the valve device 110 and generate an error signal, should a malfunction state of the separator 110 be determined.

[0042] Figure 2 shows an example of a centrifugal separator 110 configured to separate a liquid phase from a gaseous phase by means of a rotational movement of a rotor 230. The separator 110 may be configured similarly to the one discussed in connection with figure 1. The separation takes place in a separator housing 210 defining at least a part of separation space 220, in which a plurality of separation members 232 are rotatably arranged. The separation members 232 are attached to a rotor 230 extending through the separation phase 220 in an axial direction X, around which the rotor 230 and the separation members 232 are arranged to rotate during operation. The rotor 230 may be brought to rotate by a driving member 234, which, for example, may be a turbine wheel driven by a stream of oil, such as engine lubricating oil. Other driving means are also possible, such as an electric motor.

[0043] The separation members 232 provide a separation aid in the form of a stack of frustoconical separation discs. Interspaces are provided between the separation discs 232, through which the crankcase gas can travel from an inner periphery towards an outer periphery while being separated into the liquid phase and the gaseous phase as the separation members 232 rotate in the separation space 220. In figure 2, only some of the separation discs 232 are indicated. It will be appreciated that while the frustoconical separation discs 232 in the present example are stacked with their wide ends facing downwards, other configurations are also possible. In an example, the separation discs 232 may be stacked with their wide ends facing upwards. In further examples, other types of separation aids may be utilised, including, e.g., axially extending vanes projecting radially outwards from the rotor 230.

[0044] During operation, the flow of crankcase gas is guided into the separator 120 through the gas inlet 112, which in the present example is arranged in an upper, centre portion of the separator housing 210. The gas enters the stack of separation members 232 from a central portion thereof. As the separation members 232 rotate, heavy constituents such as oil particles are separated from the gas and propelled as droplets against a circumferential inner wall surface 214 of the separator housing 210. The separated liquid phase may be transported by gravity along the inner wall 214 and through a lower bearing 236, or via through-holes next to the lower bearing 236, to a lower end portion 212 of the separator 110 and further through a liquid outlet 215. Should the separator 110, during use, be arranged in a different orientation with respect to the direction of gravity, the liquid outlet 214 may be arranged at a portion of the housing 210 being the lowest one, with respect to the direction of gravity. The flow of crankcase gas, gaseous phase, and liquid phase through the separator 110 are indicated by arrows in figure 2.

[0045] The separator 110 also includes a valve device 120, which is connected to the gas outlet 114. The valve device 120 may be connected in series with the gas outlet 114 and the conduit 130, such that the flow of gas exiting the separator 110 passes through the valve device 120 on its way to the conduit 130. The valve device 120 provides a variable constriction of the flow path, which may be used to protect the separator 110 and the crankcase 12 from excessive negative pressures, such as negative pressures generated by a downstream turbocharger 135.

[0046] The variable constriction may be formed by a valve element 122, such as a diaphragm or a membrane, which may be actuated by the pressure differential between the interior and the exterior of the valve device 120. The valve element 122 may interact with a valve seat 125 to form the variable constriction of the flow path. Moving the valve element 122 towards the seat 125 reduces the cross-sectional area of the flow path, resulting in a constriction, whereas moving the valve element 122 away from the seat 125 opens the flow path. In absence of a pressure difference, or low pressure differences (such as less than 30 mbar), the valve element 122 may be arranged in a fully open state to allow the cleaned crankcase gas to flow relatively unrestricted towards the conduit 130. When actuated, the valve element 122 can move towards a seat 125 of the valve device 120 to constrict the flow path. The valve element 122 may move gradually towards the seat 125, thereby creating a variable or gradual constriction of the flow path. The extent to which the valve element 122 constricts the flow path may depend on the degree of negative pressure in the flow path. In some examples, the valve element 122 may start moving towards the seat 125 for negative pressure differences exceeding 30 mbar and be arranged in its fully constricted state (in which it abuts against the seat 125) for pressure differences of about 100 mbar.

[0047] The valve element 122 may hence be understood as a moving part that constricts or opens the flow path depending on the pressure conditions under which it operates. In some examples, an elastic element 127, such as a spring, may be arranged to push the valve element 122 away from the seat 125 to allow the valve device 110 to be in a normally open state. In other examples, the elastic element may be integrated with the valve element 122. The valve element 122 may, for example, be formed as one or more flexible membranes or flaps arranged in the first state when not actuated and bending or flexing towards the seat 125 when actuated.

[0048] As a result, the spring constant provided by the elastic element 127 determines the force that needs to be overcome by the pressure difference in order to shift the valve element 122 from the first state, in which the flow path is fully open, to the second state in which the flow path is fully constricted. In the present examples, the threshold, i.e., the actuating pressure difference, is about 30 mbar. Hence, the flow path may be fully open for negative pressures ranging from about 0-30 mbar and more or less constricted for higher pressure differences.

[0049] A sensor 140 is arranged to generate a signal indicative of a movement or position of the valve element 122. The signal may then be utilised by the control unit 150 to determine the operational state of the valve device 110. In an example, the sensor signal may be used to determine whether the valve element 122 is arranged in the first, fully open state, in the second, fully constricted state, or in any position therebetween. As the pressure in the conduit 130 depends, inter alia, on the operation point of the engine 10 (and thus the operation of the turbocharger 135), it may be possible to determine an expected behaviour or state of the valve device 110 for a specific operation point of the engine 10. For example, if the engine 10 is idling the pressure differential over the valve element 122 may be close to zero. The valve device 110 can therefore be expected to be in the fully open state, in which the valve element 122 has been moved away from the seat 125. If the engine 10 is operating under full load and at full speed, on the other hand, the turbocharger 135 may generate a negative pressure in the conduit 130 that may cause the valve device 120 to constrict the flow path. The valve element 122 may then be expected to move towards the first seat 125 to assume the second state, in which the flow passage 124 is constricted to prevent excessive negative pressures to reach the interior of the separator 110.

[0050] This operational state of the valve device 110, as determined by the movement or position of the valve element 122, may be compared with a reference state associated with the specific operation point of the engine. If the operational state does not correlate to the reference state, a malfunction state may be declared. The malfunction state may, for example, indicate that the separator 110 is not working as expected, such as being disconnected from the flow of exhaust gas or being bypassed. Such a malfunction state may be declared if, for example, the valve element 122 is arranged in the first state, in which the flow passage is fully open, while the engine 10 is operating at full load and speed. A malfunction state may also be determined in case the valve element 122 is arranged in the second state, in which the flow passage is fully constricted, while the engine is idling (idling corresponds to a low load and speed, resulting in zero or close to zero pressure difference). This may indicate that the valve device 120 is malfunctioning, such as the valve element 122 being stuck or tampered with.

[0051] Generally, the sensor 140 may produce a signal indicative of presence or absence of a movement of the valve element 122, or a change in state of the valve element 122. Further, the signal may comprise information that can be used by control unit to quantify the movement and provide detailed information about, for example, the speed, direction, and pattern of the movement. In some examples, the control unit may determine how the valve element 122 moves over time or, in different words, determine a distance d between a reference point and a measuring point on the valve element 122 as a function of time. This information may be used to determine how quickly the valve device 120 reacts to changes in pressure in the conduit 130, the operational stability of the valve device 120 over time, and valve health. Unexpected or irregular movement patterns of the valve element 122 may indicate a malfunctioning of the valve device 120, for example caused by wear or a need for maintenance of the valve device 120. Furthermore, time-dependent movement information of the valve element 122 may allow for pressure fluctuations in the crankcase ventilation system, such as the conduit 130 or the separator 110, to be determined and analysed. Correlating the temporal behaviour of the valve element 122 with known changes in system pressure may also help understanding if the system works as intended or if the separator 110 or the valve device 120 is malfunctioning.

[0052] In the specific example depicted in figure 2, the sensor 140 is an optical sensor employing infrared (IR) light to continuously monitor the position of the valve element 122. The IR sensor 140 measures the distance d between a measuring point on the valve element 122 and the IR sensor 140 and provides this information in a sensor signal conveyed to the control unit 150. Based on this information, the control unit 150 can determine the operational state of the valve device 120.

[0053] A method for determining a state of a centrifugal separator, which may be configured similarly as the centrifugal separators 110 in figures 1 and 2, will now be described with reference to figures 3A and 3B.

[0054] Figure 3 A outlines a method in which the flow of gas is guided SI 10 through the separator 110 to allow at least some of the contaminants to be separated from the flow of gas. The flow of gas may enter the separator 110 at the gas inlet 112, pass through the stack of rotating separation members 232 and exit the separator 110 at the gas outlet 114 as discussed above in connection with figure 2. Thereafter, the flow of gas may be transported SI 20 away from the separator 110 towards a conduit 130. The flow path may pass through the valve device 120, which may be arranged to connect the gas outlet 114 to the conduit 130.

[0055] The valve device 120 comprises a valve element 122 for controlling S130 a variable constriction of the flow path. The constriction may be controlled S130 based on a pressure differential between the flow path and an exterior of the valve device 120, such that an increase in pressure differential results in an increased constriction of the flow path, and vice versa.

[0056] According to the example depicted in figure 3 A, a signal, which is indicative of a movement of the valve element 122, is received S140 by a control unit 150. The signal may be generated by a sensor 140 arranged to detect or measure a movement or position of the valve element 122 in response to the pressure differential. By analysing the signal, the control unit 150 may determine SI 50 the operation of the valve device 120 and hence the state of the centrifugal separator 110. An example on how to determine the state of the separator 120 is depicted in figure 3B. In a first step, the control unit 150 determines SI 52 an operational state of the valve device 120 based on the signal from the sensor 140. The operational state may, for example, correspond to the valve element 122 being arranged in the first, fully open state or in the second, fully constricted state, or in any intermediate state. Referring to the example in figure 2, the operational state of the valve device 120 may be based on the measured distance d between a measuring point on the valve element 122 and the sensor 140. The distance d may vary with the position of the valve element 122 relative to the sensor 150, ranging from a minimum when the flow path is fully open and in a maximum distance when the flow path is fully constricted (i.e., the valve element 122 abutting against the seat 125). Hence, by monitoring the distance d, the control unit 150 may be capable of determining whether the valve element 122 is arranged in the fully open state, the fully constricted state, or in an intermediate state. The change in distance d may also be observed, for example as a function of time, wherein an increasing distance d indicates that the valve element 122 is moving towards the seat 125 and hence acting to constrict the flow path, whereas a decreasing distance d indicates that the valve element 122 is moving away from the seat 125, acting to open the flow path. The operational state may hence be determined in various ways, indicating, for example, that the flow path is fully open, fully constricted, partly constricted, or about to assume any of these states.

[0057] A reference state, associated with an operation point of the engine, may be determined SI 54. The operation point typically includes variables such as engine speed, load, and fuel intake. As the operation point affects the flow rate of the exhaust gases, which in turn drive the turbine wheel 234 of the turbocharger 135, the operation point of the engine 10 can be correlated to the negative pressure generated by the turbocharger 135. This, in turn, makes it possible to correlate an expected operational state of the valve device 120 to the operation point of the engine 10. An increasing engine load and speed may, for example, lead to an increased activity of the turbocharger 135, which in turn increases the pressure drop created by the turbocharger 135. It can therefore be expected that the valve element 122 responds by constricting the flow passage. A certain actuation pattern of the valve element 122 may hence be determined, associating a given operation point of the engine 10 with a specific reference state.

[0058] By comparing S156 the operational state of the valve device 120, as determined based on the sensor signal, with the reference state, it may be possible to determine SI 58 if the centrifugal separator 110 is malfunctioning. Any deviation from the expected actuation pattern of the valve element 122 may indicate a malfunction state, for example caused by the separator 110 being disconnected or bypassed. Should such a malfunction state be determined, the control unit may generate SI 60 an error signal.

[0059] The control unit 150 of the present disclosure may generally comprise one or more processors and one or more non-transitory computer-readable media storing first computer executable instructions that, when executed by the one or more processors, cause the system to perform at least parts of the actions shown in figures 3A-B and described above. Generally, the control unit 150 may comprise circuitry which is configured to implement (using one or more non-transitory computer-readable media) the functionality described herein. Suitable processors for the execution of a program of instructions include, by way of example, both general and special purpose microprocessors, and the sole processor or one of multiple processors or cores, of any kind of computer. The processors can be supplemented by, or incorporated in, ASICs (application-specific integrated circuits). Those skilled in the art will understand that the above-described exemplary embodiments may be implemented in any suitable software, hardware, or firmware configuration or combination thereof. An exemplary hardware platform for implementing the exemplary embodiments may include, for example, an Intel x86 based platform with compatible operating system, a Windows OS, a Mac platform and MAC OS, a mobile device having an operating system such as iOS, Android, etc. In a further example, the exemplary embodiments of the abovedescribed method may be embodied as a program containing lines of code stored on a non-transitory computer readable storage medium that, when compiled, may be executed on a processor or microprocessor.

[0060] Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practising the claimed invention, from a study of the drawings, the disclosure, and the appended claims. Moreover, in the drawings and specification, there have been disclosed preferred embodiments and examples of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for the purpose of limitation. The scope of the invention is set forth in the following claims, in which the word ‘comprising’ does not exclude other elements or steps, and the indefinite article ‘a’ or ‘an’ does not exclude a plurality.

Claims

CLAIMS1. A system (100) for separating contaminants from a flow of gas from a crankcase of an internal combustion engine (10), comprising: a centrifugal separator (110) comprising a gas inlet (112) and a gas outlet (114) for guiding the flow of gas through the separator to allow at least some of the contaminants to be separated from the flow of gas; a valve device (120) arranged at the gas outlet and defining a flow path for connecting the gas outlet to a conduit (130) transporting the flow of gas away from the separator, the valve device comprising a valve element (122) forming a variable constriction of the flow path, the valve element being actuatable by a pressure differential between the flow path and an exterior of the valve device; a sensor (140) arranged to generate a signal indicative of a movement of the valve element; and a control unit (150) configured to determine an operational state of the valve device based on the signal.

2. The system according to claim 1, wherein the valve element is arrangeable in a first state in which the flow path is fully open and in a second state in which the flow path is fully constricted.

3. The system according to claim 2, wherein the valve device comprises a seat (125), and wherein the valve element in the second state abuts against the seat to constrict the flow path.

4. The system according to claim 3, wherein the valve device comprises a leak structure allowing a leak flow between the valve element and the seat in the second state.

5. The system according to any of claims 2-4, wherein the valve element is configured to switch from the first state to the second state in response to a negative pressure in the flow path exceeding a predetermined threshold.

6. The system according to any of claims 2-6, wherein the valve element is configured to be arranged in the first state when not actuated.

7. The system according to claim 6, wherein the valve device comprises an elastic element (127) configured to push the valve element away from the seat.

8. The system according to any of the preceding claims, wherein the valve element comprises a membrane.

9. The system according to any of the preceding claims, wherein the valve device is configured to be connected to a turbocharger (135) generating the negative pressure.

10. The system according to any of the preceding claims, wherein the sensor is a mechanical sensor or an optical sensor.

11. The system according to any of the preceding claims, wherein the control unit is configured to: determine a reference state associated with an operation point of the engine; compare the operational state of the valve device with the reference state; and determine, based on a deviation between the operational state and the reference state, a malfunction state of the centrifugal separator.

12. A method for determining a state of a centrifugal separator for separating contaminant from a flow of gas from a crankcase of an internal combustion engine, comprising: guiding (SI 10) the flow of gas through the separator to allow at least some of the contaminants to be separated from the flow of gas; transporting (SI 20) the flow of gas away from the separator through a flow path defined by a valve device;controlling (SI 30), by means of a valve element of the valve device, a variable constriction of the flow path based on a pressure differential between the flow path and an exterior of the valve device; receiving (S140), from a sensor, a signal indicative of a movement of the valve element; and determining (S150) the state of the centrifugal separator based on the signal.

13. The method according to claim 12, wherein determining the state of the centrifugal separator comprises: determining (SI 52) an operational state of the valve device based on the signal; determining (SI 54) a reference state associate with an operation point of the engine; comparing (SI 56) the operational state of the valve device with the reference state; and determining (SI 58), based on a deviation between the operational state and the reference state, a malfunction state of the centrifugal separator.

14. The method according to claim 13, comprising: generating (SI 60) an error signal indicating the malfunction state of the centrifugal separator.

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