DE102010029322B4 - Pressure relief valve of a device for venting the crankcase of an internal combustion engine and device with such a pressure relief valve - Google Patents

Abstract

Pressure-limiting valve (1) of a device (2) for venting the crankcase of an internal combustion engine, the pressure-limiting valve (1) being arranged in a gas channel (21) of the device (2) that discharges gas from the crankcase of the internal combustion engine, the pressure-limiting valve (1) being one has an adjustable valve body (10) between an end position in the closing direction and an open position, which is preloaded with a force acting in the closing direction and which is adjustable in the opening direction by the crankcase ventilation gas when a predeterminable pressure difference is reached, characterized in that the valve body (10) at least for Part is formed from a gas-permeable medium (12) through which crankcase ventilation gas can flow in the end position in the closing direction of the valve body (10), and that the gas-permeable medium (12) is a fiber medium.

Description

The invention relates to a pressure relief valve of a device for venting the crankcase of an internal combustion engine, the pressure relief valve being arranged in a crankcase ventilation gas discharging gas channel of the device, the pressure relief valve having a valve body which can be adjusted between an end position in the closing direction and an open position, the valve body having is biased by a force acting in the closing direction and which is adjustable in the opening direction by the crankcase ventilation gas when a predeterminable pressure difference is reached. In addition, the invention relates to a device for venting the crankcase of an internal combustion engine, with such a pressure relief valve.

The older, republished publication WO 2011/089006 A1 discloses a valve for controlling a gas flow from a pressure side to a suction side of the valve, with a valve seat, with at least one opening from the pressure side to the suction side as a valve opening, a valve closure, in particular a valve plate, the valve opening being closable by means of the valve closure, and one Valve bearing on which the valve closure is spring loaded. The valve closure has one or more gas passage openings from the pressure side to the suction side of the valve. In this case, one, several or all of the gas passage openings can be opened for the gas passage from the pressure side to the suction side when the valve is closed. Furthermore, one, several or all gas passage openings can have first liquid separation elements and / or can be designed as first liquid separation elements.

The publication DE 20 2005 009 990 U1 shows an oil separator, for which it is characteristic that an inflow cross section in front of a valve plate is divided into a plurality of partial inflow cross sections. Here the valve body is always a closed plate, which no longer allows flow when the valve is in the closed position.

A pressure relief valve and a device for venting the crankcase of an internal combustion engine of the aforementioned type are also from the document EP 1 285 152 B1 known. The valve body of the pressure relief valve is designed here as a baffle plate on which larger oil droplets from the crankcase ventilation gas are deposited as a result of flow deflection when the valve body is in the open position. When the valve body is in its end position in the closing direction, the pressure relief valve is closed gas-tight and all flow is blocked. Thus, the pressure relief valve in its closed state cannot contribute to de-oiling the crankcase ventilation gas of the internal combustion engine. When the pressure relief valve is open, a certain oil mist separation takes place due to the flow deflection and impact separation, but its effect is mainly limited to larger oil droplets. This leads to the fact that finer oil droplets, such as are increasingly present in the crankcase ventilation gas in modern internal combustion engines, reach the clean gas side of the device through the pressure relief valve and thus enter the intake tract of the internal combustion engine, for example, and can cause malfunctions in the operation of the internal combustion engine.

The object of the present invention is therefore to specify a pressure relief valve of a device for venting the crankcase of an internal combustion engine and a device with such a pressure relief valve, which offer improved oil mist separation, in particular with regard to finer droplets.

According to the invention, the part of the task relating to the pressure relief valve is achieved with a pressure relief valve of the type mentioned at the outset, which is characterized in that the valve body is formed at least in part from a gas-permeable medium through which crankcase ventilation gas can flow in the closing position of the valve body, and that the gas permeable medium is a fiber medium.

With the invention, a pressure relief valve is created which advantageously brings about an oil mist separation from the crankcase ventilation gas of the internal combustion engine in each of its positions. In the end position in the closing direction of the valve body, crankcase ventilation gas flows through the gas-permeable medium from which the valve body consists at least in part. In this case, oil droplets supplied with the gas accumulate on the surface and inside of the gas-permeable medium, this effect also occurring for finer oil droplets if the gas-permeable medium is suitably designed. Within the gas-permeable medium, the small oil droplets combine to form larger drops and finally an oil film. The oil can be transported from the medium via the flow pressure of the gas in the form of large drops or as a film to the clean side and is then easy to separate and can be removed by gravity; with a suitable spatial arrangement and alignment of the valve body, the oil can also be partially discharged from the medium by gravity in such a way that the oil does not return to the gas flow can occur. As a result, a large proportion of the oil mist entrained is removed from the gas flow of the crankcase ventilation gas. The fact that crankcase ventilation gas flows through the valve body even when the valve body is in the closing direction is not only not harmful for the ventilation of the crankcase, it is even useful. If the valve body of the pressure relief valve is moved into its open position in the presence of corresponding operating conditions, that is to say with a correspondingly large pressure difference, a parallel, second flow path is released through the then opening valve gap in addition to the flow path through the gas-permeable medium. On this second flow path, parallel to the separation in the gas-permeable medium, an oil mist separation takes place through flow deflection and impingement separation in the area of the valve body, the gas-permeable medium also ensuring a high efficiency in impingement separation due to a rough and porous surface structure, which is significantly better than in one smooth baffle plate according to the state of the art. At the same time, even when the pressure relief valve is open, a partial gas flow can still flow through the gas-permeable medium, the separation effect described above occurring. In a first phase of use, the gas-permeable medium is still maximally gas-permeable and a high separation efficiency is achieved via the oil mist separation in the medium. In the course of its service life, the gas-permeable medium then becomes increasingly clogged with deposits from the gas flow, but the surface of the medium still remains effective as a baffle for the oil mist separation by baffle separation. The gas-permeable medium is a fiber medium, since such a medium has the required properties and is inexpensive.

It is also preferably provided that the gas-permeable medium is a felt or nonwoven or paper. These media offer favorable structural properties for the intended use and are also inexpensive materials that are easy to process. In addition, they can be changed and adjusted as required with regard to their properties, such as flow resistance or wettability with oil, which allows the oil mist separation to be optimized for different operating conditions.

A further embodiment suggests that the gas-permeable medium consists of natural fibers or plastic fibers or metal fibers or glass fibers or carbon fibers or mineral fibers or a mixture of two or more of these fibers. The gas-permeable medium can thus be selected and optimized in accordance with its various properties, such as flow resistance, surface properties, temperature resistance, chemical resistance, etc., for the prevailing conditions of use.

In order that the gas-permeable medium maintains a secure cohesion and permanent dimensional stability over the intended period of use, the fibers of the gas-permeable medium are preferably needled together or water jet consolidated or glued or sintered.

In order to make the valve body mechanically sufficiently stable overall without significantly impairing its permeability to the crankcase ventilation gas, it is preferably proposed that the valve body be formed from the gas-permeable medium by a grid-like carrier and at least one body carried by the carrier. The body made of the gas-permeable medium can be permanently connected to the carrier, for example by gluing or welding. Alternatively, there is the possibility of releasably connecting the body to the support from the gas-permeable medium, e.g. to jam or to hook or to hook up, so that the body can be exchanged from the gas-permeable medium while the carrier is being used if necessary.

As mentioned above, a preloading force acting in its closing direction is applied to the valve body, the force being set such that the pressure limiting valve opens at a predeterminable pressure difference. A simple and therefore inexpensive way of generating the preload force is that the carrier preferably consists of a resilient material and is shaped and connected to the rest of the pressure relief valve in such a way that it itself applies the preload force acting on the valve body in the closing direction. A separate spring is advantageously not required here to generate the preload force.

In a further embodiment of the pressure limiting valve it is provided that the valve body is formed solely and completely by a self-supporting body made of the gas-permeable medium. In this embodiment, only the gas-permeable medium is used for the valve body, as a result of which an additional carrier as part of the valve body is omitted here.

If the valve body itself is not suitable for applying the necessary preload force in the closing direction, then the preload force acting in the closing direction is expediently generated by at least one spring acting on the valve body.

The valve body of the pressure relief valve can be designed geometrically different; but preferably the valve body is either plate-shaped with a rear guide shaft or flat leaf spring. In both versions, the valve body is inexpensive to manufacture as a mass part and can be connected to the rest of the valve with little effort and can be guided in an adjustable manner.

A sharp flow deflection is favorable for effective oil mist separation by impact separation. In order to promote such a sharp flow deflection in the region of the pressure-limiting valve, a valve seat cooperating with the valve body is preferably formed by an arrangement of a plurality of mutually parallel gas guide channels running perpendicular to a front side of the valve body facing the valve seat. The gas guide channels act as a flow straightener, which ensures that the gas flow hits the valve body practically at every point at an essentially right angle.

Since the distance between the valve seat and the valve body is only relatively small even in its end position in the opening direction, the gas flow here describes a sharp deflection by 90 °, which most of the oil droplets carried cannot follow due to their inertia. This leads to an impact of the oil droplets on the side of the valve body facing the valve seat, where the body from the gas-permeable medium is expediently located, or, in other words, to an impact separation.

In order to ensure a function of the body from the gas-permeable medium in the pressure relief valve that is effective over sufficiently long operating times, it is expedient to protect the gas-permeable medium against mechanical damage. For this purpose, the invention proposes that the valve body and / or a valve seat cooperating with the valve body have stop means which, in the end position in the closing direction of the valve body, keep the body out of the gas-permeable medium at a distance from the valve seat. On the one hand, this prevents the gas-permeable medium from being compressed to an undesirable degree by pressing it against the valve seat. This also prevents the gas-permeable medium from freezing to the valve seat in the event of frost and the presence of moisture. In this way, harmful tearing of parts, such as fibers, out of the body from the gas-permeable medium for the function of the gas-permeable medium can be avoided.

A further development of the invention provides that the pressure limiting valve has an adjustment path limitation acting on it in the closing direction of the valve body and in the end position in the closing direction of the valve body keeping a remaining valve gap open. In this embodiment of the valve, two partial gas flows already flow through the valve when the valve body is in its closing position, namely a first partial flow through the open valve gap and a second partial flow through the gas-permeable medium. Oil mist is separated from both partial flows. This design of the pressure relief valve creates the advantageous possibility of using identical and structurally identical pressure relief valves for different applications, in particular for internal combustion engines with different volume flows of crankcase ventilation gas, with the exception of the adjustment path limitation. The characteristic of the pressure relief valve can e.g. can only be changed by changing the adjustment travel limit and optimized for the associated internal combustion engine. In the case of internal combustion engines with smaller volumetric flows of crankcase ventilation gas, the valve gap remaining in the end position in the closing direction of the valve body is kept small or the valve gap is entirely dispensed with, while in the case of larger internal combustion engines the valve gap remaining in the end position in the closing direction of the valve body is kept larger. The adjustment path limitation can be fixed or adjustable.

The solution to the second part of the task, relating to the device for venting the crankcase of an internal combustion engine, is achieved according to the invention with a device according to the preamble of claim 13, which is characterized by a pressure relief valve according to one of claims 1 to 12, as described above. In such a device, the pressure relief valve can be used with great technical benefit, as a result of which the device receives a good oil mist separation function overall and reliably protects the crankcase of the associated internal combustion engine against impermissibly high pressures.

A first embodiment of the device provides that it has at least one separate oil mist separator, in particular a single cyclone or multicyclone or coalescence or impactor separator or a plate separator or an electrostatic filter, and that the gas channel in which the pressure limiting valve is arranged is an oil mist separator bypass channel . In this embodiment, the separate oil mist separator ensures the essential separation of oil mist from the crankcase ventilation gas. The pressure relief valve in the device carries its part of the oil mist separation for the through the parallel to the separate oil mist separator Pressure relief valve with the valve body in the end position in the closing direction, that is to say with partial flow of the crankcase ventilation gas flowing during normal operation. If the separate oil mist separator is overloaded, which manifests itself in an increased pressure difference, the pressure limiting valve opens and releases an enlarged flow cross section through the bypass channel to relieve the oil mist separator. The pressure relief valve in the open position of the valve body also ensures good oil mist separation from the partial gas flow flowing through the now open valve gap by means of flow deflection and impact separation.

In an alternative embodiment of the device, the pressure relief valve is the only means of the device for separating oil mist from the crankcase ventilation gas. In this embodiment, without a separate oil mist separator, the device can be designed in a particularly simple and particularly space-saving manner, which also achieves particularly low manufacturing costs with a lower, but still acceptable in many applications, oil mist separation efficiency.

In order to keep the pressure in the crankcase below a predetermined maximum pressure even under extreme conditions and to ensure good oil mist separation in applications in which particularly large volume flows of crankcase ventilation gas occur, the device can expediently have a plurality of pressure limiting valves connected in parallel. The individual pressure relief valves and their distance between the valve body and seat in the open position can then remain relatively small, which means that a sharp flow deflection and effective impact separation is maintained in each pressure relief valve in its open position. In total, the several pressure relief valves are thus able to separate a higher proportion of oil droplets, in particular smaller oil droplets, from the gas flow of the crankcase ventilation gas than a single pressure relief valve with a correspondingly larger area and a greater distance between the valve body and seat in the open position.

In order to achieve a soft response or release when pressure relief is required via a plurality of pressure limiting valves, it is preferably proposed that the plurality of pressure limiting valves have different opening pressures. This ensures that the pressure relief valves do not all open at the same time but one after the other and that only as many pressure relief valves are opened as are required for the respective pressure relief. The different opening pressures of the several pressure relief valves can e.g. can be achieved in that their valve bodies have differently sized effective areas, different preloading forces and / or bodies made of gas-permeable media of different porosity.

In order to keep production and assembly as simple as possible, the device is preferably designed in the form of a module which can be attached to the internal combustion engine as a unit and which, in addition to the at least one pressure relief valve, also has at least one oil mist separator and / or a crankcase pressure control valve and / or a separated oil-collecting space, if necessary with oil return to the oil sump of the associated internal combustion engine. This enables a more or less extensive integration of various functions into the module, which can itself be expediently connected to the associated internal combustion engine via a flange connection with simultaneous establishment of the required flow connection.

• 1 ein Druckbegrenzungsventil in einer ersten Ausführung, mit in Endstellung in Schließrichtung befindlichem Ventilkörper, im Längsschnitt,
• 2 das Druckbegrenzungsventil aus 1 mit in Öffnungsstellung befindlichem Ventilkörper, im Längsschnitt,
• 3 das Druckbegrenzungsventil in einer zweiten Ausführung, im Längsschnitt,
• 4 den Ventilkörper des Druckbegrenzungsventils aus 3 in einer perspektivischen Ansicht schräg von unten,
• 5 das Druckbegrenzungsventil in einer dritten Ausführung, im Längsschnitt,
• 6 den Ventilkörper des Druckbegrenzungsventils aus 5 in einer perspektivischen Ansicht schräg von unten,
• 7 das Druckbegrenzungsventil in einer vierten Ausführung, im Längsschnitt,
• 6 den Ventilkörper des Druckbegrenzungsventils aus 7 in einer perspektivischen Ansicht schräg von unten,
• 9 das Druckbegrenzungsventil in einer fünften Ausführung, im Längsschnitt,
• 10 den Ventilkörper zusammen mit einem Körper aus einem gasdurchlässigen Medium, in einer weiteren Ausführung, in Draufsicht,
• 11 den Ventilkörper aus 10 im Längsschnitt gemäß der Linie XI-XI in 10,
• 12 den Ventilkörper aus 10 ohne den Körper aus dem gasdurchlässigen Medium, in Draufsicht,
• 13 das Druckbegrenzungsventil in einer weiteren Ausführung, in Draufsicht,
• 14 das Druckbegrenzungsventil aus 13 im Längsschnitt,
• 15 eine Anordnung aus zwei miteinander verbundenen, unterschiedlich großen Druckbegrenzungsventilen, im Längsschnitt,
• 16 eine Anordnung aus einem Druckbegrenzungsventil und einem separaten Ölnebelabscheider, im Längsschnitt, und
• 17 ein ein Druckbegrenzungsventil und weitere Komponenten enthaltendes Modul, im Längsschnitt.

Exemplary embodiments of the invention are explained below with reference to a drawing. The figures in the drawing show:

• 1 a pressure relief valve in a first embodiment, with the valve body in the end position in the closing direction, in longitudinal section,
• 2nd the pressure relief valve 1 with valve body in the open position, in longitudinal section,
• 3rd the pressure relief valve in a second embodiment, in longitudinal section,
• 4th the valve body of the pressure relief valve 3rd in a perspective view obliquely from below,
• 5 the pressure relief valve in a third embodiment, in longitudinal section,
• 6 the valve body of the pressure relief valve 5 in a perspective view obliquely from below,
• 7 the pressure relief valve in a fourth embodiment, in longitudinal section,
• 6 the valve body of the pressure relief valve 7 in a perspective view obliquely from below,
• 9 the pressure relief valve in a fifth version, in longitudinal section,
• 10th the valve body together with a body made of a gas-permeable medium, in a further embodiment, in plan view,
• 11 the valve body 10th in longitudinal section along the line XI-XI in 10th ,
• 12 the valve body 10th without the body from the gas permeable medium, in top view,
• 13 the pressure relief valve in a further embodiment, in plan view,
• 14 the pressure relief valve 13 in longitudinal section,
• 15 an arrangement of two interconnected, different sized pressure relief valves, in longitudinal section,
• 16 an arrangement of a pressure relief valve and a separate oil mist separator, in longitudinal section, and
• 17th a module containing a pressure relief valve and other components, in longitudinal section.

1 shows a first pressure relief valve 1 in longitudinal section, with a valve body 10th of the valve 1 is in its end position in the closing direction. The valve body 10th is here in the form of a flat, openwork plate with a guide shaft extending from the rear 14 educated. The valve body bears on its front, in the drawing below 10th a body 12 ' from a gas-permeable medium, here a fiber medium. The valve body 10th acts with its the fiber medium body 12 ' load-bearing side with an annular valve seat here 15 together. Below the valve seat 15 and the valve body 10th there is a raw gas area 22 ; on the other side of the valve body 10th there is a clean gas area 24th within a valve housing shown only partially here 19th .

By means of his leadership 14 is the valve body 10th in the longitudinal direction of the shaft 14 inside one as part of the valve body 19th trained shaft guide 28 slidably supported and guided. By means of the leadership 14 surrounding coil spring 13 is the valve body 10th preloaded with a force acting in its closing direction, i.e. downwards in the drawing.

The fiber medium body 12 ' is permeable to crankcase ventilation gas, such as through the fiber medium body 12 ' and the valve body 10th extending flow arrow is indicated. Inside the fiber medium body 12 ' Oil droplets entrained in the crankcase ventilation gas are captured and thus separated from the gas stream. The separated oil is in an oil collection channel 27 ' radially outside and below the valve seat 15 collected and can be derived from there in a manner not shown, for example in the oil sump of an associated internal combustion engine.

If on both sides of the valve body 10th a pressure difference occurs that exceeds a predefinable limit value, the valve body 10th against the force of the spring 13 increasingly far from the valve seat 15 lifted off until it reaches its maximum opening position at a second, even greater pressure difference, as shown in 2nd is shown. This will place between the valve seat 15 and a part of the valve body 10th forming fiber medium body 12 ' an increasingly widening valve gap 18th released, which forms an additional, increasing flow path for the crankcase ventilation gas. With the pressure relief valve partially or fully open 1 So the gas can partly through the fiber medium body 12 ' of the valve body 10th and the other part through the valve gap 18th stream. From the through the fiber medium body 12 ' flowing partial stream is entrained oil mist in the form of oil droplets in the fiber medium body 12 ' separated from the gas stream. From the partial flow through the valve gap 18th flows, oil mist is also separated, namely by sharp flow deflection and impact separation, whereby the oil droplets entrained in the gas stream cannot follow the sharp flow deflection and because of their inertia on the fiber medium body 12 ' or on the inner surface of the valve body 10th surrounding valve housing 19th hit and put down there. The oil separated from the gas flows is in the oil collecting channel 27 ' collected and derived from this.

3rd also shows in longitudinal section another pressure relief valve 1 . The valve body 10th corresponds to that previously based on 1 and 2nd described execution. The difference is in 3rd the valve seat 15 executed, namely now as an arrangement of a plurality of relatively small, parallel to each other and perpendicular to the flat side of the valve body 10th running gas guide channels 16 . The gas channels 16 form a gas flow rectifier, which ensures that all through the gas guide channels 16 flowing partial gas flows at a right angle to the valve body 10th and the valve seat carried by it 15 facing fiber medium body 12 ' to meet. This achieves the greatest possible sharpness of deflection for the gas flow. The valve seat 15 is also here in a filter housing 19th formed which a raw gas area 22 below the valve body 10th and a clean gas area 24th above the valve body 10th separates from each other. The leadership 14 of the valve body 10th leading shaft guide 28 is here as a separate, with the rest of the valve housing 19th locked component executed.

4th shows in a perspective view obliquely from below the valve body 10th of the pressure relief valve 1 out 3rd . The viewer is facing in 4th that from the fiber medium 12 existing fiber medium body 12 ' . The fiber medium body 12 ' is on a part of the valve body 10th forming, provided with openings 11 attached, for example glued or welded. Thus, the valve body is also here 10th total flow of crankcase ventilation gas. From the back of the carrier 11 extends the leadership shaft 14 in a direction perpendicular to the flat side of the fiber medium body 12 ' up.

5 shows in the same representation as 3rd another pressure relief valve 1 , whose valve housing 19th and shaft guide 28 with the example below 3rd are identical. The valve body is now different 10th trained, specifically its sponsor 11 . In the example in 5 owns the carrier 11 of the valve body 10th several lifting means distributed radially on the outside in the circumferential direction 17th that towards the valve seat 15 down, in the drawing down, over the lower end of the fiber medium body 12 ' protrude. This ensures that in the end position in the closing direction of the valve body 10th of the pressure relief valve 1 only the sling 17th to the valve seat 15 create while the fiber medium body 12 ' at a short distance from the valve seat 15 is held. This avoids freezing and damage to the fiber medium body caused thereby 12 ' in the case of frosty ambient temperatures and the presence of moisture.

By means of the lifting gear 17th or alternatively by means of one with the leadership 14 in the closing direction of the valve body 10th interacting, fixed or adjustable adjustment limit can be ensured that the valve body 10th also in its end position in the closing direction a predeterminable valve gap in the pressure relief valve 1 keeps open.

6 shows a perspective view obliquely from below the valve body 10th of the pressure relief valve 1 out 5 . On the face of the valve body facing the viewer 10th lies the fiber medium body 12 ' . About the circumference of the valve body 10th A total of four slings are distributed here 17th provided the the fiber medium body 12 ' protrude slightly in the axial direction. The leadership is in the background 14 of the valve body 10th visible.

7 shows again in longitudinal section another pressure relief valve 1 . This is the valve housing 19th with the shaft guide 28 again essentially identical to the examples according to 3rd and 5 . Is different in 7 the valve body 10th educated. The valve body also carries here 10th on its front, that is, in the drawing below, the fiber medium body 12 ' . The fiber medium body becomes radially outside 12 ' part of the valve body 10th forming carrier 11 protrudes radially. The valve seat 15 is surrounded radially on the outside by an elevated ring area, which together with the carrier 11 a sling 17th forms. The sling 17th again ensures that in 7 shown end position in the closing direction of the valve body 10th only the lifting gear is in contact while the fiber medium body 12 ' still a short distance from the valve seat 15 Has.

In 8th is the valve body 10th from the pressure relief valve 1 to 7 again shown obliquely from below in a perspective view. The fiber medium body faces the viewer 12 ' , the radially outside of the ring-shaped sling here 17th as part of the carrier 11 is towered over. From the back of the carrier 11 extends the leadership shaft 14 up.

Yet another version of the pressure relief valve 1 is in the 9 shown, again in a longitudinal section. A characteristic of this example is that the valve body 10th completely through a fiber medium body 12 ' is formed. A carrier is here for the valve body 10th not provided. On the in 9 rear of the valve body pointing upwards 10th the spring works 13 in the closing direction, i.e. downwards. The bottom of the valve body 10th or fiber medium body 12 'acts with the valve seat, which is once again simply ring-shaped here 15 together.

In the in 9 shown open position of the valve body 10th this is due to a correspondingly large pressure difference from the valve seat 15 lifted off. A first partial flow of raw gas 22 in the clean gas area 24th flowing crankcase ventilation gas flows through out of the fiber medium body 12 ' existing valve body 10th through, with an oil mist separation from the gas stream taking place in the manner already described. A second partial flow of the crankcase ventilation gas is in the valve gap 18th twice sharply deflected by approximately 90 °, which results in an impact separation of oil droplets on the one hand on the underside of the fiber medium body 12 ' and on the other hand on the inner circumference of the valve housing 19th is effected. The impact separation at the bottom of the from the fiber medium 12 existing fiber medium body 12 ' is particularly effective because of the valve seat 15 facing end face of the fiber medium body 12 ' forms a rough and porous surface, which firmly holds and absorbs impacting oil droplets. The inner circumference of the valve housing 19th can be carried out with a surface favoring the impact separation, for example with an annular, hollow cylindrical body made of a gas-permeable material, such as fiber material.

The 10th , 11 and 12 show, in contrast to the previous examples, a flat leaf spring-like valve body 10th for a pressure relief valve.

In 10th in is the valve body 10th in top view together with a fiber medium body 12 ' shown. This is the left part of the valve body in the drawing 10th as a round, openwork straps 11 formed with which the fiber medium body 12 ' is connected here by a barbed mandrel. A middle section of the valve body 10th is designed as a narrow strip and functionally forms a spring 13 . An end section adjoining it to the right with an opening serves as the fastening end 14 ' with which the valve body 10th can be attached to a valve housing, for example by riveting.

11 shows the valve body 10th out 10th on average according to the cutting line XI-XI in 10th . Up in 11 on the left is the openwork straps 11 . The spring closes on the right 13 forming narrow middle section and on the far right is the fastening end 14 ' of the valve body 10th . With the bottom of the carrier 11 is the fiber medium body 12 ' from the gas-permeable fiber medium 12 connected by means of the mandrel. Thus, the valve body is also here 10th in the area of his fiber medium body 12 ' permeable to crankcase ventilation gas, even if the valve body 10th in the pressure relief valve in the end position in the closing direction.

12 shows in the same direction as 10th the valve body 10th without the fiber medium body 12 ' . It is particularly clear here that the carrier 11 which here is the left part of the valve body 10th is perforated to allow gas to flow therethrough.

When opening the pressure relief valve with the valve body 10th according to the 10th - 12 ensures a pressure difference exceeding a specifiable limit value for elastic bending of the valve body 10th in the area of its the feather 13 forming narrow section. The valve body is used to ensure this function 10th for example from a spring sheet blank or from an elastic-flexible plastic part.

In the 13 and 14 is another version of the pressure relief valve 1 , once in plan view and once in longitudinal section. Like the top view according to 13 is illustrated, the valve body 10th here carried out flat rectangular and consists of a carrier in the form of a coarse fabric or grid 11 and an associated, also flat rectangular fiber medium body 12 ' from the fiber medium 12 . The carrier 11 has resilient properties and consists, for example, of a wire mesh made of stainless steel wire or of a one-piece molded grid made of an elastic-flexible plastic. In 13 is the fiber medium body 12 ' with the underside of the carrier facing away from the viewer 11 connected. Right in 13 there is an attachment end 14 ' of the valve body 10th on which the valve body 10th is connected to a valve housing. Under the left part of the valve body 10th is the valve seat indicated with a dashed line 15 .

According to the cut in 14 can the valve body 10th also be designed so that the lattice-like carrier 11 in the fiber medium body 12 ' from the fiber medium 12 is embedded, creating better cohesion of the valve body 10th can be reached. Under the left part of the valve body 10th is the valve seat 15 . Under the valve seat 15 the raw gas area is located here again 22 ; over the valve body 10th is the clean gas area 24th . Right in 14 is the valve body 10th with its attachment end 14 ' with the valve housing 19th connected, here by means of a compressed holding mandrel. Between the valve seat 15 and the attachment end 14 ' lies the feather 13 forming narrow section of the valve body 10th .

15 shows in a longitudinal section an arrangement of two differently sized pressure relief valves 1 in a common valve housing 19th . The two pressure relief valves 1 are already in accordance with the 3rd and 4th explained embodiment executed; reference is made to the description there. The only difference is the size of the pressure relief valves 1 , that means here the diameter and thus the area of the respective valve body 10th . With the same design of the respective assigned spring 13 result from the difference in pressure difference between the raw gas area 22 and clean gas area 24th acted surfaces of the valve body 10th different opening pressures. This means that the two pressure relief valves 1 not open at the same time, but at two different pressure differences one after the other, whereby the valve 1 with the valve body 10th with the larger area opening first. In this way, if a pressure relief of the crankcase of an associated internal combustion engine is required, a graded, soft response is achieved, which is advantageous for the function of the crankcase ventilation. This version also enables a modular design, depending on the volume flows to be expected during operation Crankcase ventilation gas one or more pressure relief valves with one or more different sizes can be used to meet the respective needs. Alternatively, springs of different strengths can also be used to achieve different opening pressures 13 and / or fiber medium body 12 different porosity in otherwise identical or with different sized valve bodies 10th executed pressure relief valves 1 be used.

In 16 is again in a longitudinal section an example of a combined, compact arrangement of a pressure relief valve 1 and a separate oil mist separator 23 shown. Here again is in a valve housing 19th a valve seat 15 formed, which, as already explained above in other examples, by a large number of parallel small gas guide channels 16 is formed. The valve body 10th of the pressure relief valve 1 in 16 corresponds to the example according to 1 - 4th , whose description is referred to in this regard.

Below and radially outside of the valve seat 15 is on the valve housing 19th a hollow cylindrical fiber medium body as a separate oil mist separator 23 provided the, as well as the valve seat 15 with the valve body 10th , a raw gas area 22 from a clean gas area 24th separates.

In operating states in which between the raw gas range 22 and clean gas area 24th there is a differential pressure below a predeterminable limit value, crankcase ventilation gas flows in a first, usually larger partial flow through the separate oil mist separator 23 from the raw gas sector 22 in the clean gas area 24th , with oil droplets carried in the gas stream in the oil mist separator 23 intercepted and thus separated from the gas stream. A second, usually smaller, partial flow of the crankcase ventilation gas flows through the fiber medium body 12 ' of the valve body in the end position in the closing direction 10th of the pressure relief valve 1 , here in the same way as in the oil mist separator 23 Oil droplets are separated from the gas stream.

As soon as an operating condition occurs in which the pressure difference between the raw gas area 22 and clean gas area 24th the valve body is exceeded 10th against the force of the spring 13 from the valve seat 15 lifted, the pressure relief valve 1 so open. As a result, a valve gap is released as an additional flow path, through which a third partial flow of the crankcase ventilation gas from the raw gas area is then released 22 in the clean gas area 24th can flow. From this third partial flow, oil droplets through the in the area of the valve seat 15 and the valve body 10th and its fiber medium body 12 ' occurring sharp flow deflection and impact separation eliminated.

If the fiber medium body 12 after a longer period of use, the second partial flow is omitted, but this does not lead to a significant impairment of the function, because the impact separation on the valve body is still retained.

17th finally shows an example of a venting device 2nd , which as a prefabricated module that can be connected to an internal combustion engine 20th is executed, which has several functional units, including a pressure relief valve 1 , contains. The pressure relief valve 1 is inside the module 20th in a gas channel 21st arranged by a raw gas area 22 to a clean gas area 24th leads. The pressure relief valve 1 is here according to the example in the 1 and 2nd executed, to the description of which reference is made.

Next to the pressure relief valve 1 contains the module 20th two separate oil mist separators 23 , which are designed here in the form of cyclones of different sizes, connected in parallel.

As a further functional unit is in the module 20th in the top part of a crankcase pressure control valve 25th arranged, which ensures that the pressure in the crankcase of an associated internal combustion engine does not fall below a lower limit.

Finally, the module shown has 20th in its lowest part there is an oil collection room 27 , in which the module 20th led crankcase ventilation gas collects separated oil. On the one hand, oil becomes on the pressure relief valve 1 separated from the gas stream in the manner described above, in the oil collecting channel 27 ' collected and from there into the oil collection room 27 derived. On the other hand, oil mist separators designed as cyclones are used here 23 Oil separated and also in the oil collection room 27 derived. This oil collecting room 27 can, as is known per se, be connected to the oil sump of an associated internal combustion engine via a check valve or a siphon.

Reference symbol list

1

Pressure relief valve

10th

Valve body

11

carrier

12

Fiber medium

12 '

Fiber medium body

13

feather

14

Leadership

14 '

Fastening end

15

Valve seat

16

Gas guide channels

17th

Slings

18th

Valve gap

19th

Valve body

2nd

Venting device

20th

module

21st

Gas channel for 1

22

Raw gas area

23

Oil mist separator

24th

Clean gas area

25th

Crankcase pressure control valve

26

Clean gas outlet

27th

Oil collection room

27 '

Oil collecting channel

28

Shaft guide

Claims (18)

Pressure-limiting valve (1) of a device (2) for venting the crankcase of an internal combustion engine, the pressure-limiting valve (1) being arranged in a gas channel (21) of the device (2) that discharges gas from the crankcase of the internal combustion engine, the pressure-limiting valve (1) being one has an adjustable valve body (10) between an end position in the closing direction and an open position, which is preloaded with a force acting in the closing direction and which is adjustable in the opening direction by the crankcase ventilation gas when a predeterminable pressure difference is reached, characterized in that the valve body (10) at least for Part is formed from a gas-permeable medium (12) through which crankcase ventilation gas can flow in the end position in the closing direction of the valve body (10), and that the gas-permeable medium (12) is a fiber medium. Pressure relief valve after Claim 1 , characterized in that the gas-permeable medium (12) is a felt or nonwoven or paper. Pressure relief valve after Claim 1 , characterized in that the gas-permeable medium (12) consists of natural fibers or plastic fibers or metal fibers or glass fibers or carbon fibers or mineral fibers or a mixture of two or more of these fibers. Pressure relief valve according to one of the Claims 2 to 3rd , characterized in that the fibers of the gas-permeable medium (12) are needled to one another or water jet consolidated or glued or sintered. Pressure relief valve according to one of the Claims 1 to 4th , characterized in that the valve body (10) is formed by a grid-like carrier (11) and at least one body (12 ') carried by the carrier (11) from the gas-permeable medium (12). Pressure relief valve after Claim 5 , characterized in that the carrier (11) consists of a resilient material and is shaped and connected to the rest of the pressure relief valve (1) in such a way that it itself applies the preloading force acting on the valve body (10) in the closing direction. Pressure relief valve according to one of the Claims 1 to 4th , characterized in that the valve body (10) is formed solely and completely by a self-supporting body (12 ') made of the gas-permeable medium (12). Pressure relief valve according to one of the Claims 1 to 5 or after Claim 7 , characterized in that the biasing force acting in the closing direction is generated by at least one spring (13) acting on the valve body (10). Pressure relief valve according to one of the Claims 1 to 8th , characterized in that the valve body (10) is plate-shaped with a rear guide shaft (14) or flat leaf spring-like. Pressure relief valve according to one of the Claims 1 to 9 , characterized in that a valve seat (15) cooperating with the valve body (10) is formed by an arrangement of a plurality of gas guide channels (16) which are parallel to one another and run perpendicular to a front side of the valve body (10) facing the valve seat (15). Pressure relief valve according to one of the Claims 1 to 10th , characterized in that the valve body (10) and / or a valve seat (15) cooperating with the valve body (10) have stop means (17) which, in the end position in the closing direction of the valve body (10), the fiber medium (12) at a distance from the Hold the valve seat (15). Pressure relief valve according to one of the Claims 1 to 11 , characterized in that it an adjustment path limitation acting on the valve body (10) in the closing direction of the valve body (10) in the closing position of the valve body (10) has a remaining valve gap open. Device (2) for venting the crankcase of an internal combustion engine, with a pressure limiting valve (1), which is arranged in a crankcase ventilation gas from the crankcase of the internal combustion engine gas channel (21) of the device (2), the pressure limiting valve (1) being between an end position Has valve body (10) adjustable in the closing direction and an open position, which is preloaded with a force acting in the closing direction and which is adjustable in the opening direction by the crankcase ventilation gas when a predeterminable pressure difference is reached, characterized by a pressure relief valve (1) according to one of the Claims 1 to 12 . Device after Claim 13 , characterized in that it has at least one separate oil mist separator (23), in particular a single cyclone or multicyclone or coalescence or impactor separator or a plate separator or an electrostatic precipitator, and that the gas duct (21) in which the pressure limiting valve (1) is arranged is an oil mist separator bypass passage. Device after Claim 13 , characterized in that the pressure relief valve (1) is the only means of the device (2) for separating oil mist from the crankcase ventilation gas. Device according to one of the Claims 13 to 15 , characterized in that it has a plurality of pressure relief valves (1) connected in parallel. Device after Claim 16 , characterized in that the plurality of pressure relief valves (1) have different opening pressures. Device according to one of the Claims 13 to 17th , characterized in that it is designed as a module (20) which can be attached to the internal combustion engine as a unit and which, in addition to the at least one pressure limiting valve (1), also has at least one oil mist separator (23) and / or a crankcase pressure control valve (25) and / or a separated oil has receiving collecting space (27).

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