Patent Description:
It has been an interest in reducing emissions produced by internal combustion engines, ICEs, for decades. Reductions have been achieved in various ways, such as by using catalytic converters and improving the efficiency of ICEs to reduce the consumption of fuel. However, such reductions mainly target exhaust gases that would be discharged through an exhaust pipe of the ICE. Thus, there has been an increased interest in reducing the emissions of other exhaust gases, such as crankcase blow-by gases. Additionally, vehicle emission standards are starting to include standards for all vehicle emissions, thereby including emissions from crankcase blow-by gases, which further increases the interest in reducing such emissions.

It is of interest to provide a crankcase ventilation system for separating oil particles from crankcase blow-by gases of an internal combustion engine which may reduce crankcase blow-by gas emissions. It is a further interest to provide an improved quality, i.e. less oil particles, of crankcase blow-by gas which is released to the atmosphere, or sent back to a combustion chamber of an ICE. These interests are met by providing an arrangement having the features in the independent claims.

Hence, according to an aspect of the present disclosure, there is provided a crankcase ventilation system for separating oil particles from crankcase blow-by gases of an internal combustion engine, ICE. The system comprises a housing and a disc stack separator. The disc stack separator may be arranged within the housing. The disc stack separator comprises a chamber and a rotor. The chamber may be arranged within the disc stack separator. The rotor comprises an oil separating element arranged within the chamber and spaced from one or more walls of the chamber, and a shaft configured to rotatably mount the oil separating element. The oil separating element may comprise a plurality of stacked plates, wherein the plates may be conical. The disc stack separator further comprises a first gas inlet for supplying the crankcase blow-by gases to the oil separating element along the shaft, and a first gas outlet for discharging the at least partially oil separated gases. The system further comprises a filter element. The filter element comprises a second gas inlet, a second gas outlet, and a filter arranged between the second gas inlet and the second gas outlet. The first gas inlet is configured to be connected to a crankcase blow-by crankcase outlet of the ICE. The first gas outlet is connected to the second gas inlet.

The present disclosure is based on the concept of using a disc stack separator connected to a filter element to increase the separation of oil particles from crankcase blow-by gases. A disc stack separator provides a filtration rate of substantially <NUM>% for particles having a size above <NUM>. The filtration rate may further be dependent on a flow rate of the crankcase blow-by gases, such that a filtration rate of substantially of <NUM>% may be achieved for particles having particles having a size below <NUM>, such as below <NUM>, <NUM> or <NUM>, when the flow rate is reduced. Further, a disc stack separator may not require regular service. However, the filtration rate of a disc stack separator may decrease with regards to particles having a size less than, for example, <NUM>. On the other hand, a filter element has a filtration rate of substantially <NUM>%, regardless of the size of the particles. However, a filter element inherently has a low loading capacity, a short lifetime and requires regular service or replacement. By first using a disc stack separator to separate oil particles having a size above <NUM> before the crankcase blow-by gases are sent to the filter element, the load for the filter element is greatly reduced. In other words, the amount of particles which has to be separated by the filter element, in comparison to only using a filter element, is greatly reduced. Thereby, the lifetime of the filter element is extended. The lifetime of the filter element may be increased at least <NUM> times. Further, the loading capacity of the filter element is increased. In other words, the filter element may be used for a longer time before a maximum capacity of the filter element is reached. Alternatively, the size of the filter of the element may be decreased without decreasing the required service interval. Thus, combining a disc stack separator and a filter element achieves a synergistic effect as the advantages of both technologies are present.

By the term "oil particles" it is meant, for example, oil droplets and/or oil mist. The disc stack separator may comprise rotating means configured for rotating the shaft of the disc stack separator. The rotating means may comprise a turbine wheel, or an electric motor. The turbine wheel may be configured to be operated, for example, with oil, i.e. being oil-powered, via a belt, or a gear. The disc stack separator may be attached to an engine block of the ICE. The disc stack separator may be attached to, or integrated with a part of the engine block of the ICE, such as, for example, a cam cover. However, the disc stack separator may be a standalone component, i.e. not integrated with the engine block of the ICE. The first gas inlet may be connected to the crankcase blow-by outlet of the ICE, or the engine block, via an adapter conduit. The adapter conduit may be customizable, such that the system may be connected to many different kinds of ICEs. The system may be configured to release the filtered crankcase blow-by gases from the second gas outlet to an external space, such as the atmosphere.

The filter may be composed of a layer of arranged fibers, wherein the fibers may comprise polypropylene and/or fiberglass. The filter may be an Efficient Particulate Air, EPA, filter, high-efficiency particulate air, HEPA, filter or an Ultra Low Particulate Air, ULPA, filter. Thereby the filtration capacity of the system may be increased. An EPA filter may have a retention rate between <NUM>%to <NUM>%. A HEPA filter may have a retention rate between <NUM>,<NUM>% to <NUM>,<NUM>%. An ULPA filter may have a retention rate which is higher than a HEPA filter. A higher filter retention rate may lead to the filter reaching a maximum load capacity quicker. Thus, using disc stack separator may allow for using filters having a higher retention rate, thereby increasing the retention of particles.

One way of preventing crankcase blow-by gases from being released into the atmosphere has been by sending the crankcase blow-by gases back to a combustion chamber of the ICE. The second gas outlet may be configured to be connected to an intake manifold or an intake side of the ICE. Thus, the crankcase blow-by gases which has been cleaned by the system may be fed back to the ICE via the intake manifold. The intake manifold may be connected to combustion chambers of the ICE. Oil particles being present in the gas fed to the ICE may reduce the efficiency of the ICE and/or increase the risk of a malfunction of the ICE. Thus, the present system may improve the performance of the ICE.

The filter element may further comprise a pressure regulation valve. The first gas outlet may be connected to the second gas inlet via the pressure regulation valve. Alternatively, the second gas outlet may be connected to the pressure regulation valve. The pressure regulation valve may comprise a diaphragm. The pressure regulation valve may further comprise a spring configured to pre-load the pressure regulation valve. The pressure regulation valve may allow for a more efficient feeding of cleaned crankcase blow-by gases to the intake manifold, or intake side, of the ICE.

The filter element may comprise a positive crankcase ventilation, PCV, valve, wherein the first gas outlet may be conned to second gas inlet via the PCV valve. The PCV valve may provide an alternative way to allow for a more efficient feeding of cleaned crankcase blow-by gases to the intake manifold, or in intake side, of the ICE.

The pressure regulation valve may be arranged within the housing. Correspondingly, the PCV valve may be arranged within the housing. Thereby providing a more robust and compact system, which may increase the durability of the system. The housing may comprise a detachable portion, a lid, or a latch, which may allow a user to access the pressure regulation valve. The system may further comprise one or more bypass valves. The one or more bypass valve(s) may be configured to, for example, allow gas to be released if a pressure difference between two sides of a bypass valve exceeds a threshold, or if a gas flow level of the system is exceeded.

The first gas outlet may be arranged through a wall of the housing. For example, the first gas outlet may be connected to an opening in a wall of the housing. Thereby, the second gas inlet of the filter element may be securely connected to the housing and thereby to the first gas outlet. The pressure regulation valve may comprise an outlet, wherein the outlet may be arranged through a wall of the housing, or be connected to an opening in a wall of the housing, and thereby connectable to the first gas outlet.

The chamber may be formed by the housing. In other words, the housing may comprise the chamber. The chamber being formed, or comprised, by the housing may be understood as, for example, internal walls of the housing forming the chamber.

The housing may further comprise an oil reservoir. By the term "oil reservoir" is further meant, for example, oil chamber, or drive oil chamber. The disc stack separator may be configured to discharge oil separated from the crankcase blow-by gases into the oil reservoir. Thus, the disc stack separator may be configured to collect the separated oil into the oil reservoir. The oil reservoir may be connected to the chamber of the disc stack separator. The system may be configured to deliver oil from the oil reservoir to the ICE.

During operation of the ICE and the crankcase ventilation system, the filter element may be continuously filtering the crankcase blow-by gases and thereby retain oil particles. When the amount of oil particles retained by the filter reaches a certain level, the filter needs service or replacement. The arrangement of the filter element according to the present disclosure provides a more accessible filter element, and thereby provides easier replacement of a filter of the filter element. The present crankcase ventilation system may further be configured to collect oil, or oil particles, from the filter element. Further, the system may comprise an oil drain channel configured to deliver the collected oil to the oil reservoir. The filter element may be configured to allow retained oil to drain, or flow, into the oil drain channel. The drainage of flow may be higher when the ICE is not operating. Further, the force of gravity may assist the drainage of oil from the filter element. Thus, the crankcase ventilation system allows for drainage of the filter element, especially when the ICE is not operating. Thereby, the time before a filter needs to be serviced or replaced may be increased.

The first gas outlet may be connected to the second gas inlet via a gas conduit, thereby providing the ability of arranging the housing and the filter housing at a distance from each other. The gas conduit may further be configured as, for example, a pipe, a tube, such as a connecting tube, or a channel. A system comprising a pressure regulation valve, or a PCV valve, for which the first gas outlet is connected to the second gas inlet via the pressure regulation valve, or the PCV valve, may comprise at least one gas conduit which may be arranged between the first gas outlet and the pressure regulation valve, or the PCV valve, and/or between the pressure regulation valve, or the PCV valve, and the second gas outlet.

The filter element may comprise a filter housing. The filter may be arranged within the filter housing. Thus, the system may comprise a housing, in which the disc stack separator is arranged, and a filter housing, in which the filter element is arranged. A system having two separate housings allows for an increased flexibility when connecting the system to an ICE. As there is limited amount of space in a vehicle, it may be hard to fit a crankcase ventilation system into such a space. Further, the temperatures in some of the spaces around an ICE may not be suitable for all components of a crankcase ventilation system. Thus, by providing a system split into two housings the system can be placed more optimally with regards to fitting inside the space and/or with regards to temperatures inside the space.

The filter element may comprise a filter chamber, in which the filter may be arranged within the filter chamber. The second inlet may be arranged through a first wall of the filter chamber. The second outlet may be arranged through a second wall of the filter chamber. The second wall may be the same wall as the first wall, or a different wall than the first wall. Therefore, the second inlet and the second outlet may be arranged through the same wall, or through different walls. The filter chamber may be comprised by the housing. Thus, the housing, which may comprise a plurality of parts which may be welded and/or fastened together, may comprise the filter chamber of the filter element and the chamber of the disc stack separator. At least one side of the filter chamber may comprise a shape which is adapted to fit to a side of the chamber of the disc stack operator. A housing comprising the chamber and the filter chamber may be understood as an integrated solution, in which both of the disc stack separator and the filter element are realized within the same arrangement, or component. Thus, a more compact system may be provided. The arrangement comprising both of the technologies further may provide an easier installation of the system as fewer components need to be attached to an ICE.

The filter chamber may comprise a detachable cover. The filter chamber may comprise six sides. The detachable cover may form one of the six sides. Further, the detachable cover may form one of the six sides and portions of sides neighboring the side formed by the detachable cover. For example, The detachable cover may form a first side, and portions of the four sides neighboring the first side. The detachable cover may be attached to the rest of the filter chamber by fastening means, such as, for example, screws or bolts. Further, the detachable cover may be attached to the rest of the filter chamber via a hinge. The detachable cover may allow for a user to access the filter within the filter chamber, thereby providing easier replacement of a filter.

The second outlet may be arranged through the detachable cover. Alternatively, the second outlet may be arranged through a side, or a wall of the filter chamber.

At least a portion of the chamber of the disc stack separator may be abutting at least a portion of the filter chamber. The at least a portion of the filter chamber may comprise at least a portion of one or more sides of the chamber, and the at least a portion of the filter chamber may comprise at least a portion of one or more sides of the filter chamber. Thus, a more compact system may be provided.

This and other aspects of the present disclosure will now be described in more detail, with reference to the appended drawings showing embodiment(s) of the disclosure.

<FIG> schematically shows a crankcase ventilation system <NUM> according to an exemplifying embodiment of the present disclosure.

The system <NUM> comprises a housing <NUM>. The housing <NUM> comprises an upper portion 10a and a lower portion 10b. The upper portion 10a has a generally cylindrical shape comprising a top and a bottom. The lower portion 10b also has a generally cylindrical shape comprising a bottom and a top. The upper and lower portions 10a, 10b are connected and sealed together by means of fastening means <NUM>, which are illustrated in <FIG> as, but not limited to, screw nuts <NUM>. More specifically, the bottom of the upper portion 10a is connected to the top of the lower portion 10b. The housing <NUM> further comprises attachment means <NUM> configured for attaching the housing <NUM> to an internal combustion engine, ICE. The attachment means <NUM> are illustrated in <FIG> as, but not limited to, threaded holes adapted to receive screw nuts. The position of the attachment means <NUM> on the housing <NUM> may be adapted to fit to a specific ICE.

The system <NUM> further comprises a disc stack separator (not shown; see <FIG> or <FIG>) configured for, at least partially, separating oil particles from crankcase blow-by gases of the ICE, and is arranged within the housing <NUM>. The disc stack separator comprises a first gas inlet <NUM> configured to be connected to a crankcase blow-by outlet of the ICE and for supplying the crankcase blow-by gases from the ICE to the disc stack separator. The first gas inlet <NUM> is arranged through the top of the upper portion 10a of the housing <NUM>. The disc stack separator further comprises a first gas outlet <NUM> for discharging the, at least partially, oil-separated gases from the disc stack separator. The first gas outlet <NUM> is arranged through a circumferential side of the upper portion 10a of the housing <NUM>. In other words, the first gas outlet <NUM> is arranged through a wall of the housing <NUM>.

The housing <NUM> may further comprise an oil reservoir (not shown; see <FIG>). The disc stack separator may be configured to discharge oil separated from the crankcase blow-by gases into the oil reservoir. The oil reservoir may be arranged within the lower portion 10b of the housing <NUM>.

The system <NUM> further comprises a filter element <NUM>. The filter element <NUM> comprises a filter housing <NUM> and a filter <NUM> arranged within the filter housing <NUM>. The filter element <NUM> further comprises a gas inlet <NUM> and a gas outlet <NUM>, which are arranged through opposite sides of the filter housing <NUM>. The filter <NUM> is arranged between the gas inlet <NUM> and the gas outlet <NUM>. Further, the filter <NUM> is connected between the gas inlet <NUM> and the gas outlet <NUM> such that gas inlet <NUM> and the gas outlet <NUM> are fluidly connected via the filter <NUM>. In other words, gases have to pass through the filter <NUM> in order to travel from the gas inlet <NUM> to the gas outlet <NUM>.

The first gas outlet <NUM> of the disc stack separator <NUM> is connected to the second gas inlet <NUM> of the filter element <NUM>. In <FIG>, the system <NUM> further comprises a gas conduit <NUM> which connects the first gas outlet <NUM> and the second gas inlet <NUM>, thereby allowing the filter element <NUM> to be arranged at a distance from the housing <NUM> and the disc stack operator <NUM>. It is be understood that the present disclosure is not limited to the exemplary embodiment as shown in <FIG>. For example, the filter element <NUM> may be arranged at, or attached to, the housing <NUM>. In such an exemplary embodiment, the first gas outlet <NUM> and the second gas inlet <NUM> may be directly connected to each other. However, the system <NUM> may comprise a filter element <NUM> arranged at, or attached to, the housing <NUM> and comprise a gas conduit <NUM> which connects the first gas outlet <NUM> and the second gas inlet <NUM>.

The system <NUM> may further comprise an oil drain channel <NUM> as shown in <FIG>. The oil drain channel <NUM> may be configured to deliver oil that has been retained, filtered, or captured, by the filter <NUM> to the housing <NUM>. More specifically, the drain channel <NUM> may be configured to deliver oil that has been retained, filtered, or captured, by the filter <NUM> to an oil reservoir (not shown; see <FIG> or <FIG>) of the housing <NUM>.

The second gas outlet <NUM> may be configured to be connected to an intake manifold (not shown) of the ICE. Thereby, the crankcase blow-by gases which have been filtered by the system <NUM> may be fed back into the ICE. The second gas outlet <NUM> may be connected to an intake manifold in a number of different ways. For example, the system <NUM> may comprise a secondary gas conduit configured for connecting the second gas outlet <NUM> to the intake manifold. In another example, the filter element <NUM> may be arranged at the intake manifold such that the second gas outlet <NUM> is connected directly to the intake manifold.

<FIG> schematically shows a cross-sectional view of a crankcase ventilation system <NUM> according to an exemplifying embodiment of the present disclosure. It should be noted that <FIG> comprises features, elements and/or functions as shown in <FIG> and described in the associated text. Hence, it is also referred to <FIG> and the description relating thereto for an increased understanding.

The shown cross-section of the crankcase ventilation system <NUM> is made along a longitudinal axis of a disc stack separator <NUM> of the system <NUM>. Thereby, an inside of the disc stack separator <NUM> is shown. The system <NUM> comprises a housing <NUM> in which the disc stack separator <NUM> is arranged within. The housing <NUM> comprises an upper portion 10a and a lower portion 10b. The disc stack separator <NUM> comprises a chamber <NUM> and a rotor <NUM>. The chamber <NUM> is at least in part defined by inner walls of the upper portion 10a of the housing <NUM>. In other words, the chamber <NUM> is formed by the housing <NUM>. The rotor <NUM> comprises an oil separating element <NUM> and a shaft <NUM>. The oil separating element <NUM> is arranged within the chamber <NUM>. The shaft <NUM> is arranged from a top of the upper portion 10a of the housing <NUM> to a bottom of the lower portion 10b of the housing <NUM>,and is thereby arranged through the chamber <NUM>. The oil separating element <NUM> is rotatably mounted on the shaft <NUM>. Further, the oil separating element <NUM> is arranged within the chamber <NUM> and is spaced from walls of the chamber <NUM> such that there is space between walls of the chamber <NUM> and the oil separating element <NUM>.

The disc stack separator <NUM> further comprises a rotating means <NUM>. The rotating means <NUM> is illustrated in <FIG> as a turbine wheel mounted to the shaft <NUM> and arranged in the lower portion 10b of the housing <NUM>. However, the rotating means <NUM> is not limited to the exemplary embodiment as shown in <FIG>, and may be, for example, configured as an electric motor. The rotating means <NUM> is configured to rotate the shaft <NUM>, thereby rotating the oil separating element <NUM>. In <FIG>, the rotating means <NUM> is configured to rotate with the shaft <NUM>. However, the present disclosure is not limited to a rotating means <NUM> configured to rotate with the shaft <NUM>, and may comprise a fixed nozzle configured to rotate the rotating means <NUM>, thereby rotating the shaft <NUM>.

The housing <NUM> as illustrated in <FIG> may be understood to comprise an oil reservoir <NUM>. The oil reservoir <NUM> may be defined by a space within the lower portion 10b of the housing <NUM>. The housing <NUM> may comprise an oil channel between the upper portion 10a of the housing <NUM> and the lower portion 10b of the housing. Phrased differently, the system <NUM> may comprise an oil channel between the chamber <NUM> and the oil reservoir <NUM>. The oil channel may be configured to deliver oil which has been separated by the disc stack separator <NUM> from the crankcase blow-by gases into the oil reservoir <NUM>. In other words, the disc stack separator <NUM> may be configured to discharge oil separated from the crankcase blow-by gases into the oil reservoir <NUM>. A rotating means <NUM> comprising a turbine wheel, as indicated in <FIG> may be powered by oil, which may be collected in the oil reservoir <NUM> once it has jetted out from the turbine wheel.

The system <NUM> shown in <FIG> further comprises a filter element <NUM>. A difference between the system <NUM> shown in <FIG> and the exemplary embodiment as shown in <FIG> is that the oil reservoir <NUM> comprises an opening <NUM>' to which a drain channel <NUM> of the filter element <NUM> is connected, thereby allowing for the system <NUM> to deliver oil from the filter element <NUM> to the oil reservoir <NUM>.

<FIG> schematically shows a crankcase ventilation system <NUM> according to an exemplifying embodiment of the present disclosure. It should be noted that <FIG> comprises features, elements and/or functions as shown in <FIG> and <FIG> and described in the associated texts. Therefore, the following will describe the differences between the system <NUM> shown in <FIG> and the exemplary embodiments shown in <FIG> and <FIG> and described in the associated texts. Hence, it is also referred to <FIG> and <FIG> and the descriptions relating thereto for an increased understanding.

A difference between the system <NUM> shown in <FIG> and the exemplary embodiment as shown in <FIG> is that the system <NUM> shown in <FIG> comprises a pressure regulation valve <NUM>.

The pressure regulation valve <NUM> is arranged within the housing <NUM>. More specifically, the housing <NUM> shown in <FIG> comprises an auxiliary portion 50a formed on the upper portion 10a of the housing <NUM>, in which the pressure regulation valve <NUM> is arranged. The auxiliary portion 50a may comprise a detachable portion 50c which, when opened, may allow a user to access to the pressure regulation valve <NUM>. However, the present disclosure is not limited to the auxiliary portion 50a being formed on the housing <NUM>, and may, for example, be arranged at a distance from the housing <NUM>. In such an example, the first outlet <NUM> may be connected to the pressure regulation valve <NUM> via a conduit or channel. Thus, the auxiliary portion 50a may be understood as being comprised by the pressure regulation valve <NUM>.

The pressure regulation valve <NUM> is connected to the first gas outlet (not shown; see e.g. <FIG>, <FIG> or <FIG>) of the disc stack separator <NUM>, which may be arranged through a side of the upper portion 10a of the housing <NUM>. In <FIG> the pressure regulation valve <NUM> is shown to be connected to the first gas outlet by the auxiliary portion 50a being formed over the first gas outlet.

The system <NUM> may further comprise an auxiliary conduit 50b as shown in <FIG>. The auxiliary conduit 50b may be connected to the auxiliary portion 50a, in which the pressure regulation valve <NUM> is arranged, via the detachable portion 50c, or directly. The auxiliary conduit 50b may be configured for being connected to the second gas inlet <NUM> of the filter element <NUM>. Thus, the first gas outlet of the disc stack separator <NUM> may be connected to the second gas inlet <NUM> of the filter element <NUM> via the pressure regulation valve <NUM>.

<FIG> schematically shows a cross-section of a crankcase ventilation system <NUM> according to an exemplifying embodiment of the present disclosure. It should be noted that <FIG> comprises features, elements and/or functions as shown in <FIG> and described in the associated texts. Therefore, the following will describe the differences between the system <NUM> shown in <FIG> and the exemplary embodiments shown in <FIG> and described in the associated texts. Hence, it is also referred to <FIG> and the descriptions relating thereto for an increased understanding.

A difference between the system <NUM> shown in <FIG> and the exemplary embodiment as shown in <FIG> is that the system <NUM> shown in <FIG> comprises a pressure regulation valve <NUM> as shown in <FIG> and described in the associated text.

The pressure regulation valve <NUM> shown in <FIG> comprises a diaphragm <NUM> and a spring <NUM>. The diaphragm <NUM> and the spring <NUM> are arranged in the auxiliary portion 50a of the housing <NUM>. The diaphragm <NUM> and the spring <NUM> are arranged between the auxiliary portion 50a and the detachable portion 50c.

<FIG> schematically shows a crankcase ventilation system <NUM> according to an exemplifying embodiment of the present disclosure. It should be noted that <FIG> comprises features, elements and/or functions as shown in <FIG> and described in the associated texts. Therefore, the following will describe the differences between the system <NUM> shown in <FIG> and the exemplary embodiment shown in <FIG> and described in the associated texts. Hence, it is also referred to <FIG> and the descriptions relating thereto for an increased understanding.

A difference between the system <NUM> shown in <FIG> and the system shown in <FIG> and described in the associated text is that the system <NUM> shown in <FIG> further comprises a filter chamber <NUM>, which forms a part of the housing <NUM> of the system <NUM>. In other words, the housing <NUM> comprises the filter chamber <NUM>. The filter chamber <NUM> comprises a filter (not shown) which is arranged between a second inlet (not shown) and a second outlet <NUM>.

The filter chamber <NUM> has six sides, out of which three are shown in <FIG>. The second outlet <NUM> is arranged through a top side, of the six sides, of the filter chamber <NUM>. At least a portion of a side of the filter chamber <NUM>, hereinafter referenced to as the inner side of the filter chamber <NUM>, is arranged against an upper portion 10a and a lower portion 10b of the housing <NUM>. The second inlet may be arranged through the at least a portion of the inner side. The upper portion 10a and the lower portion 10b have generally cylindrical shapes. The at least a portion of the inner side has a shape adapted to be arranged flush against the upper portion 10a and the lower portion 10b. Thus, at least a portion of the disc stack separator is abutting at least a portion of the filter chamber <NUM>. The shape of the inner side may be understood as being curved. A side of the filter chamber <NUM> which is opposite the inner side, hereinafter referenced to as the outer side of the filter chamber <NUM>, has a similarly curved shape as the inner side. The remaining sides of the filter chamber <NUM> have substantially flat shapes, such that the filter chamber <NUM> has a shape in general accordance with a segment of a flat ring. It is to be understood that the present disclosure is not limited to a filter chamber <NUM> having a shape as shown in <FIG>. For example, the filter chamber <NUM> may have any number of sides, such as two, three, four, or more. Further, the shapes of the sides of the filter chamber <NUM> may be, substantially, any geometrical shape.

The filter chamber <NUM> comprises a detachable cover <NUM>. The detachable cover <NUM> is configured to be detached in order to allow access for a user to the filter arranged within the filter chamber <NUM>. The detachable cover <NUM> forms the outer side of the filter chamber <NUM> and portions of the four sides neighboring the outer side. It is to be understood that the present disclosure is not limited to comprising a detachable cover <NUM> as shown in <FIG>. For example, the detachable cover <NUM> may form a portion, or the whole, of at least any of the outer side and/or one or more of the sides of the filter chamber <NUM> neighboring the outer side.

Another difference between the system <NUM> shown in <FIG> and the system shown in <FIG> and described in the associated text is that the system <NUM> shown in <FIG> further comprises a pressure regulation valve <NUM>, but does not comprise an auxiliary conduit as shown in <FIG> which may connect the pressure regulation valve <NUM> to the second inlet. The system <NUM> shown in <FIG> comprises an auxiliary portion 50a formed on the upper portion 10a of the housing <NUM>, in which the pressure regulation valve <NUM> is arranged. The system <NUM> further comprises a detachable portion 50c which, when opened, may allow a user to access to the pressure regulation valve <NUM>. Instead of an auxiliary conduit, as shown in <FIG>, the pressure regulation valve <NUM> comprises a conduit (not shown) which is arranged within the housing <NUM> and which is connected to the second inlet, thereby providing a more compact system <NUM>.

The second outlet <NUM> is shown to be arranged through the detachable cover <NUM>. However, the second outlet <NUM> may be arranged on any of the sides of the filter chamber <NUM>.

Claim 1:
A crankcase ventilation system (<NUM>) for separating oil particles from crankcase blow-by gases of an internal combustion engine, ICE, comprising
a housing (<NUM>);
a disc stack separator (<NUM>) arranged within the housing comprising
a chamber (<NUM>);
a rotor (<NUM>) comprising
an oil separating element (<NUM>) arranged within the chamber and spaced from one or more walls of the chamber; and
a shaft (<NUM>) configured to rotatably mount the oil separating element;
a first gas inlet (<NUM>) for supplying the crankcase blow-by gases to the oil separating element along the shaft; and
a first gas outlet (<NUM>) for discharging the at least partially oil-separated gases; characterized in that the system further comprises
a filter element (<NUM>) comprising
a second gas inlet (<NUM>), a second gas outlet (<NUM>), and a filter (<NUM>) arranged between the second gas inlet and the second gas outlet, wherein the filter is composed of a layer of arranged fibers; and wherein
the first gas inlet is configured to be connected to a crankcase blow-by outlet of the ICE, wherein
the first gas outlet is connected to the second gas inlet,
and wherein the filter element is not connected to the shaft (<NUM>).