EP1201912B1 - Air intake system - Google Patents

Abstract

The system has two untreated air inlets connected to a common line to the engine. The second inlet is protected against splash and bilge water and can be closed by a closure element in a first position. The first inlet can be closed by the closure element in a second position. The closure element is movable by a motion unit, which is connected to a moisture sensor control unit with electrically conducting sensor wires and a control signal output. The system has two inlets (10,11) for untreated air connected to a common line to the engine, a closure element and a motion unit (17). The second air inlet is at a position protected against splash and bilge water and can be closed by the closure element in a first position. The first inlet can be closed by the closure element (13) in a second position. The closure element is movable by the motion unit, which is connected to a control element in the form of a moisture sensor (14) with at least two electrically conducting sensor wires at a distance apart and a signal output for controlling the motion unit.

Description

State of the art

The invention relates to an intake system for an internal combustion engine of a motor vehicle according to the preamble of patent claim 1.

From DE 196 13 860 an air intake filter device for a motor vehicle engine is known, which has a tube space which is connected to intake lines with a main inlet and a secondary inlet. Furthermore, a closing device is provided, which can alternately close an intake line and open the other intake line. The closing device is moved with an actuating device such that in a motor vehicle immersed in water, the closing device closes the main inlet and opens the secondary inlet. The actuator is operatively connected to a slide. The slide is arranged in a tube which is open at its lower end, and is sealed off from the tube. The slide is operatively connected to a permanent magnet. The closing device is operatively connected to a further permanent magnet, the permanent magnet of the closing device being rotatably arranged relative to the permanent magnet of the actuating device.

A disadvantage of this design is the considerable space required for the pipe, which is arranged in the engine compartment. This cannot be made too small, since otherwise the switching point of the arrangement cannot be precisely defined. Furthermore, this mechanical switching arrangement only reacts when the vehicle is immersed in standing water. In the event of splashing water, no sufficient pressure is built up for switching, which causes water to enter the intake system and impair the function of the engine.

DE 37 36 777 discloses a device for preventing water from entering an air filter housing of an internal combustion engine. The device has a first and a second unfiltered air inlet, a closure element being provided which closes either the first or the second unfiltered air inlet. A moisture sensor is arranged in the first raw air inlet and has two electrically conductive sensor wires. The moisture sensor is connected to control electronics which control the closure element.

The object of the invention is to provide an intake system which can be integrated into a small installation space and can prevent the entry of snow, splash water or splash water.

This object is solved by the features of claim 1.

Advantages of the invention

The intake system according to the invention for an internal combustion engine of a motor vehicle has a first unfiltered air inlet and a second unfiltered air inlet, both unfiltered air inlets being brought together in a common line and this line being communicatively connected to the internal combustion engine. Here, the two raw air inlets can also be brought together just in front of the internal combustion engine, so that each raw air inlet has its own components, e.g. has its own filter element. Each raw air inlet consists of an opening through which air can flow into the intake system and a line section which connects the opening to the line or other components which are arranged between the line and the raw air inlet. The unfiltered air inlets can be closed with a closure element, as a result of which air either enters the line communicating with the internal combustion engine through the first unfiltered air inlet or through the second unfiltered air inlet. The closure element closes the respective unfiltered air inlet completely, as a result of which air can only flow into the line through the unclosed unfiltered air inlet. The closure element can e.g. are formed by a rotating body with corresponding openings, which releases the first unfiltered air inlet in one end position and closes the first unfiltered air inlet in a second end position.

Through the line communicating with the internal combustion engine, the inflowing air is conducted directly or indirectly to the internal combustion engine. If the air is directed indirectly to the internal combustion engine, the air can be pretreated e.g. dried or chilled. If the air is led directly to the internal combustion engine, no further component is arranged in the line.

The first raw air inlet is arranged at a location in the motor vehicle that is advantageous for air intake. Here, the front area is a preferred location, since a dynamic pressure is generated in accordance with the speed of the motor vehicle and the air is pressed into the unfiltered air inlet, which improves the degree of filling of the cylinders. Furthermore, the air drawn in at the front is cooler than the air in the engine compartment. In the front area, however, snow, ice, water spray or splash water can get into the first unfiltered air inlet. Water drops of any size mixed with air are referred to as splash water. Splash water can, for example, be whirled up from the road by a vehicle in front or be generated by rain. The term blow water describes a larger amount of water, for example when crossing a river occurs as a gush of water. The second raw air inlet is arranged at a location in the motor vehicle which is less favorable for air intake, this location being protected against splashing water and splash water. Preferred locations for the arrangement of the second raw air inlet can be, for example, the engine compartment or the ventilation system.

A movement unit, which is connected to a control element, is provided for actuating the closure element. The movement unit can e.g. are formed by an electric motor or a vacuum box and can be activated with the control element, as a result of which the movement unit executes a rotational or translational movement which moves the closure element from a first end position to a second end position and thus closes either the first or the second raw air inlet. The control element is formed by a moisture sensor which has a signal output for controlling the movement unit, the moisture sensor of course also being able to be used for regulation.

The moisture sensor can be set such that it sends a signal to the movement unit by means of which the first unfiltered air inlet is closed even when there is splashing water, which also impairs the function of the internal combustion engine. With a different setting of the moisture sensor, the signal to close the first raw air inlet only takes place when the moisture sensor is surrounded by water. The signal from the moisture sensor can be used both directly and via electronics, e.g. the motor controller to be sent to the movement unit. As soon as the first raw air inlet is closed by the closure element, the second raw air inlet is opened, as a result of which the internal combustion engine receives the air sucked in by the second raw air inlet for combustion.

In an expedient embodiment of the invention, the closure element is a flap. The flap can be circular, oval or rectangular, for example, so that it closes the second unfiltered air inlet in a first position and closes the first unfiltered air inlet in a second position. Here, the valve can be arranged centrally on a valve shaft and can be moved by a rotary movement of the valve shaft. In other versions, the flap shaft is arranged in an edge area and thus enables an uninterrupted contour-free intake of raw air. In order to prevent water from entering the first unfiltered air inlet, especially when immersing it in a body of water, the flap can have a circumferential seal. Designs are also conceivable in which a first flap is arranged in the first unfiltered air inlet and a second flap is arranged in the second unfiltered air inlet, both flaps communicating are interconnected. As soon as the first flap changes its position, the second flap is also moved, whereby one raw air inlet is always open and the other raw air inlet is closed. The communicating connection of the flaps can be carried out mechanically, for example with a strut, or electronically by means of a signal which in particular emanates from the moisture sensor.

In a special embodiment, the flap has two correspondingly connected flap parts. These flap parts can be arranged at a defined angle to one another, where they touch directly or can be rigidly connected to one another by means of connecting elements. Here, the parallel arrangement of the flap parts to each other represents a special design. The flap parts can, however, also be arranged separately and only correspond to one another via the movement unit. The flap parts can e.g. have a circular, oval or rectangular cross section, with a flap part closing an unfiltered air inlet. The flap parts can have a circumferential seal, whereby the unfiltered air inlets can be sealed. By using flap parts for closing the unfiltered air inlets, the unfiltered air inlets can open into the common line in a variety of ways.

The movement unit can e.g. a lifting magnet, which is communicatively connected to the moisture sensor. The lifting magnet can perform an axial or a radial movement in order to move the closure element. As soon as the moisture sensor senses water, it sends a signal to the lifting magnet, which causes the lifting magnet to move and thus to change the position of the closure element. The solenoid reacts to the signal within a fraction of a second, which closes the first raw air inlet before water can penetrate and reach the internal combustion engine. As is known, lifting magnets have an armature, a spring, a coil, a yoke and an electrical connection.

The moisture sensor is formed by at least two electrically conductive sensor wires, the sensor wires being arranged at a distance from one another. The electrically conductive sensor wires are made of a material that has a low electrical resistance and is therefore a good electrical conductor, such as metals or metal alloys. The sensor wires arranged at a distance from one another can run parallel or at an angle to one another. The sensor wires can have any cross-section, such as circular or rectangular, whereby even the smallest cross-sections, for example cross-sections in the range of 0.01 mm ^{2, are} possible. These small sensor wire cross sections can be made possible, for example, by evaporating a metal onto a support. Both sensor wires are correspondingly connected to an evaluation unit, from which a signal for controlling the movement unit can be sent. As soon as a defined current flow between the two sensor wires is exceeded, the evaluation unit generates the signal for closing the first raw air inlet.

The suction system has a filter element with a filter medium, the moisture sensor being integrated in the filter element. The filter element is placed in a filter housing such that a raw area is sealingly separated from a clean area. The filter housing is communicating on the raw side with the first and the second raw air inlet. On the clean side, the filter housing is correspondingly connected to the internal combustion engine, and an intake air distributor, through which the cleaned air can be distributed to individual cylinders of the internal combustion engine, can be arranged between the internal combustion engine and the filter housing. Of course, two air filters can also be provided, one air filter being arranged in each raw air line. The clean air areas are then brought together in a common line.

The moisture sensor integrated in the filter element also replaces it when the filter element is replaced, as a result of which the moisture sensor can only change due to aging processes within the replacement intervals, which enables the moisture sensor to be highly reliable. The filter element can only be replaced by the filter medium, e.g. a filter fleece are formed. In other versions, the filter element has several components, e.g. a combination of the filter media with a bezel. The border can e.g. can be used as a seal or stability frame. The filter element can have any shape, the designs as a flat element, in particular as a rectangular flat element or as a hollow cylindrical filter element, being advantageous. The filter medium can consist of filter paper, in particular coated or treated filter paper. The filter medium can e.g. be flat or folded.

According to a further embodiment of the invention, the electrically conductive sensor wires are applied to a carrier, wherein the sensor wires can be embedded in the carrier or can rest on the carrier. The carrier consists of a carrier material which isolates the conductive sensor wires from one another in an insulating manner when dry. This material can be designed in such a way that it can absorb water, in which case it becomes electrically conductive. In another configuration of the carrier, the carrier material can do not absorb water, as a result of which the water is deposited on the carrier as drops. This drop of water then bridges the electrically insulating carrier material and connects the sensor wires to one another, as a result of which a current flow arises which causes the first raw air inlet to close.

In a particular embodiment of the invention, the moisture sensor is arranged in one plane with the first raw air inlet. In this case, it can be arranged at a location which is distant from the raw air inlet and which mainly comes into contact with water. The closure element is arranged above the moisture sensor at a defined distance, as a result of which there remains a sufficient reaction time between sensing water and closing the first raw air inlet. The moisture sensor is preferably arranged at a location in the engine compartment. As a result, the moisture sensor detects the ambient conditions in the engine compartment. When passing through water, the moisture sensor immerses in standing water at the same time as the unfiltered air inlet and immediately causes the first unfiltered air inlet to be closed by the closure element arranged at a higher level. The arrangement of the moisture sensor in the same plane as the first unfiltered air inlet prevents the first unfiltered air inlet from being closed too early, which would be caused by a moisture sensor arranged at a lower level.

A further embodiment of the invention provides that the moisture sensor is arranged in the first raw air inlet. The moisture sensor thus precisely detects the state that prevails in the first raw air inlet. It causes the closure element to close the first unfiltered air inlet as soon as water enters the first unfiltered air inlet. The closure element is arranged downstream of the moisture sensor, the distance between the closure element and the moisture sensor being selected such that after the water has been sensed there is still a sufficient reaction time which closes the first raw air inlet before the water flows past the closure element and reaches the internal combustion engine can. The arrangement of the moisture sensor in the first unfiltered air inlet only closes the first unfiltered air inlet when water actually enters the first unfiltered air inlet. The air is thus sucked in via the first unfiltered air inlet, which is cheaper for the internal combustion engine, and only when water actually enters the first unfiltered air inlet is the first unfiltered air inlet closed and the air is sucked in via the second unfiltered air inlet.

In a further variant of the invention, the moisture sensor can be integrated in the closure element.

In a special version, the electrically conductive sensor wires of the moisture sensor are connected directly to the filter medium. The sensor wires can e.g. glued to the filter medium, woven in or poured into the paper pulp during paper production, whereby the condition of the filter medium is exactly recorded. With increasing moisture penetration of the filter element, the air flow resistance of the filter medium increases, as a result of which the internal combustion engine receives less air for combustion, and, after it can no longer absorb water, the filter medium releases this water again on the clean side, as a result of which water penetrates to the internal combustion engine can. It is therefore advantageous to detect the moisture content of the filter element, since a signal can thus be sent from the evaluation unit to the movement unit in accordance with the filter state, as a result of which the first dirty air inlet is closed by the closure element.

The sensor wires can be arranged anywhere on the filter medium. In the case of a pleated filter medium, the sensor wires can run along, diagonally or transversely to the folds, whereby they can run either on a fold edge of the folds or on a surface of the folds. With each version, however, it must be ensured that the sensor wires have sufficient non-insulated contact with the filter medium. Furthermore, the sensor wires can be arranged on the raw side or on the clean side, the clean-side arrangement protecting the sensor wires from dirt. Furthermore, the sensor wires should preferably be arranged at the location of the filter element where the greatest moisture penetration is to be expected. As a result, the first unfiltered air inlet can already be closed when this area is moist and the remaining filter element could still absorb water. The smaller the distance between the sensor wires, the less moisture is sufficient to generate a sufficient current flow, which sends out the signal for closing the first unfiltered air inlet.

According to a further embodiment of the invention, the filter housing has voltage contacts, by means of which the moisture sensor can be supplied with voltage. These voltage contacts can be arranged at any point on the filter housing. The moisture sensor can, for example, be arranged directly in the filter space of the filter housing or outside the filter space. Since the filter housing is at least partially a stationary component, the arrangement of the voltage contacts on the filter housing means that cable lines and holders for the moisture sensor can be saved become. Designs are also conceivable in which the sensor wires are connected to the filter housing in such a way that the sensor wires touch the filter element. When the filter housing is opened, the sensor wires are lifted off the filter element. After a new filter element has been inserted, the filter housing is closed again, as a result of which the wires rest on the filter element. This means that only the used filter element is replaced and all other components can continue to be used.

It is advantageous that the moisture sensor has voltage connections which are introduced in a seal that extends around the filter medium. As a result, the moisture sensor can be supplied with voltage by mounting the filter element in the filter housing. The voltage connections can e.g. be applied to the outside of the seal, whereby corresponding contacts are provided in the filter housing. In this embodiment, the filter element is inserted into the filter housing, as a result of which the contacts of the filter element are in contact with the contacts of the filter housing and thus supply the sensor wires with voltage. Another possibility of arranging the voltage connections in the seal is to introduce the voltage connections into the interior of the seal, which takes place during the application of the sealing material.

An advantageous embodiment of the invention provides for the arrangement of several moisture sensors. Here, for example, two identically constructed moisture sensors can be provided, the moisture sensors also being able to be arranged at different points in the motor vehicle. Furthermore, the use of different moisture sensors, which differ, for example, in the distance between the sensor wires to one another or in the voltage supply, is also conceivable. The moisture sensors can be arranged directly next to one another or at different points in the motor vehicle. In one possible arrangement, for example, a highly sensitive moisture sensor can be arranged in the first unfiltered air inlet and an insensitive moisture sensor in the engine compartment below the first unfiltered air inlet. Different switching variants can thereby be formed. As soon as the less sensitive moisture sensor is immersed in water, it can output the signal to close the first raw air duct, although the highly sensitive moisture sensor has not yet come into contact with water. In a further variant, both moisture sensors come into contact with splash water, as a result of which the insensitive moisture sensor does not yet emit a signal, but the highly sensitive moisture sensor already detects a threshold value.

It is advantageous that the functionality of the moisture sensor can be tested when the internal combustion engine is started. As soon as the internal combustion engine is started, a moisture sensor test is carried out, which checks the functionality of the moisture sensor so that the moisture sensor is also functional if necessary. The functionality check can e.g. by means of a reference value which is stored in the evaluation unit. In order to indicate the state of the moisture sensor to the operator of the internal combustion engine, the moisture sensor can e.g. be connected to a control lamp which goes out after the sensor test if the sensor is working correctly. In the case of a negative sensor test in which the moisture sensor does not work properly, the indicator light can e.g. blink or light continuously. This informs the operator that the intake system is not working properly and that the first unfiltered air inlet may not be closed if water is present, which means e.g. Avoid water crossings and maintenance of the intake system is urgent.

In a special embodiment of the inventive concept, the functionality of the movement unit and the closure element can be checked when the internal combustion engine starts. Here, the movement unit and the closure element are moved each time the internal combustion engine is started, which means that all parts are functional when required and not by e.g. Corrosion is immobile. The checking of the movement unit and the closure element can e.g. are displayed with an indicator light and only go out after successful movement.

These and other features of preferred developments of the invention are evident from the claims and also from the description and the drawing, the individual features being implemented individually or in groups in the form of subcombinations in the embodiment of the invention and in other fields, and can represent advantageous and protectable versions for which protection is claimed here.

drawing

Figur 1

ein Ansaugsystem in schematischer Darstellung,

Figur 2

einen Feuchtigkeitssensor,

Figur 3

ein Filterelement,

Figur 4

ein Filterelement im Schnitt entlang der Schnittlinie A-A gemäß Figur 3,

Figur 5

einen Ausschnitt Z gemäß Figur 4

Figur 6

einen Ausschnitt Z gemäß Figur 4 in einer Variante

Figur 7

einen Ausschnitt Z gemäß Figur 4 in einer Variante und

Figur 8

ein Filterelement in einer Teilansicht

Figur 9

einen Ausschnitt Z gemäß Figur 4 in einer Variante und

Figur 10

einen Teilschnitt entlang der Schnittlinie A - A gemäß Figur 9.

Further details of the invention are described in the drawing using schematic exemplary embodiments. Here shows

Figure 1

a suction system in a schematic representation,

Figure 2

a humidity sensor,

Figure 3

a filter element,

Figure 4

4 shows a filter element in section along the section line AA according to FIG. 3,

Figure 5

a section Z according to FIG. 4

Figure 6

a section Z according to Figure 4 in a variant

Figure 7

a section Z according to Figure 4 in a variant and

Figure 8

a filter element in a partial view

Figure 9

a section Z according to Figure 4 in a variant and

Figure 10

a partial section along the section line A - A according to Figure 9.

Description of the embodiments

In Figure 1, an intake system is shown schematically. The intake system has a first unfiltered air inlet 10 and a second unfiltered air inlet 11. The unfiltered air inlets 10, 11 open into a common line 12, which is correspondingly connected to an internal combustion engine (not shown). Furthermore, a flap 13 is arranged in the intake system such that either the first unfiltered air inlet 10 or the second unfiltered air inlet 11 is correspondingly connected to the line 12. In a first flap position, which is the basic position, the second unfiltered air inlet 11 is separated from the line 12, as a result of which air can only enter the line 12 through the first unfiltered air inlet 10. And in a second flap position (shown in dash-dotted lines), the first unfiltered air inlet 10 is separated from the line 12 by the flap 13, as a result of which only air can get into the line 12 through the second unfiltered air inlet 11. In this exemplary embodiment, the first unfiltered air inlet 10 is in one piece and seamless with of the duct 12, the flap 13 defining the end of the first unfiltered air inlet 10 and the beginning of the duct 12. The second unfiltered air inlet 11 is also made in one piece with the line 12, the second unfiltered air inlet 11 opening into the line 12 at a 90 ° angle. In other embodiments, the first and the second unfiltered air inlet 10, 11 can be made in several parts with the line 12 and open into the line 12 at different angles.

To detect whether water or snow enters the intake system, a moisture sensor 14 is provided, which is arranged in the first raw air inlet 10. As soon as the moisture sensor 14, which is essentially formed by two electrically conductive sensor wires 15, comes into contact with water or snow, an electrical current flows between the sensor wires, as a result of which a signal from the moisture sensor 14 is switched to a lifting magnet by means of a switching amplifier 16 via a connecting line 16 17 is sent. The lifting magnet 17 generates a movement by means of the signal, by means of which the flap 13 is moved into the second position (shown in broken lines). In this second position, the first unfiltered air inlet 10 is closed and the second unfiltered air inlet 11 is opened. The flap 13, which has a flap shaft 18, is connected to the lifting magnet 17, as a result of which the flap shaft 18 is rotated and the flap 13 thereby moves from the first position to the second position (shown in broken lines).

The first dirty air inlet 10 is formed by a first opening 19 with a first line section 20 adjoining the first opening 19. The moisture sensor 14 is arranged at a distance A from the flap 13, so that after the moisture sensor 14 has sensed water and the flap 13 has been closed, no water has passed the flap 13 into the line 12. The distance A is designed in such a way that the water can penetrate further into the first unfiltered air inlet 10 during the reaction time, which passes between the detection of water by the moisture sensor 14 and the closing of the first unfiltered air inlet 10, without entering the line 12, which corresponds connected to the internal combustion engine to arrive. Until the water arrives at the flap 13, which forms the transition to the line 12, the flap 13 must be closed. In the second position (shown in dash-dot lines), when the flap 13 closes the first unfiltered air inlet 10, the water can penetrate as far as possible up to the flap 13, but cannot get into the line 12.

The second raw air inlet 11 is formed by a second opening 21 and a second duct section 22. The second opening 21 is at a splash and blow water protected location in the motor vehicle, which is located above the first opening 19, for example. The line sections 20, 22 can follow any spatial curves in the motor vehicle, as a result of which the intake system can be fitted into the engine compartment.

In this embodiment, the flap 13 has two flap parts 23, the flap parts 23 being rigidly connected to one another. In the first position, one of the flap parts 23 closes the second unfiltered air inlet 11. In the second position (shown in broken lines), the other flap part 23 closes the first unfiltered air inlet 10 and the second unfiltered air inlet 11 is released.

The line 12 has a raw area 24 and a clean area 25. A filter housing 26 is arranged between the raw area 24 and the clean area 25, into which a filter element 27 is sealingly inserted, as a result of which the clean area 25 is separated from the raw area 24 in a sealing manner.

The air cleaned by the filter element 27 is fed in the clean area 25 of the line 12 to an intake air distributor 28. The air supply to the intake air distributor 28 can be regulated by means of a throttle valve 29 in accordance with the operating states of the internal combustion engine.

A moisture sensor 14 is shown in FIG. The moisture sensor 14 has two electrically conductive sensor wires 15, which are arranged on a carrier 30. The carrier 30 consists of a material with electrically insulating properties, for example plastic. The carrier 30 does not absorb any water, so that an electrical current can flow between the sensor wires only after the sensor wires 15 are immersed in water. This moisture sensor therefore only reacts when there is a water hammer. Both sensor wires 15 have a separate feed line 31, which connect these sensor wires 15 to an evaluation unit 32. The evaluation unit 32 has a power line 33 which connects the moisture sensor 33 to a voltage source (not shown). The power consumption of the sensor wires 15 is determined in the evaluation unit 32. As soon as the power consumption of the sensor wires 15 exceeds a defined value, the evaluation unit 32 sends a signal via the connecting line 16 to a movement unit (not shown) which moves the closure element (not shown) and thus causes the first unfiltered air inlet (not shown) to be closed.

FIG. 3 shows a filter element 27 with an integrated moisture sensor 14. The filter element 27 has a filter medium 34, which consists of a filter paper with zigzag-shaped folds 36, and a seal 35, the seal 35 being arranged circumferentially on the filter medium 34. The moisture sensor 14 has two electrically conductive sensor wires 15 which are in direct contact with the filter medium 34. The electrically conductive sensor wires 15 run perpendicular to the folds 36 and parallel to one another, wherein they are arranged at a defined distance E from one another. The sensor wires 15 are each connected to a contact 42, the contact 42 being arranged on the seal 35. The contact 42 is formed by a rectangular metal plate which connects to voltage contacts (not shown) arranged on the housing side.

FIG. 4 shows a filter element in section along the section line AA according to FIG. 3. In this exemplary embodiment, the sensor wires 15 touch the filter medium 34 only the tips of the folds 36. The contacts 42 of the sensor wires 15 are embedded in the seal 35, which means that none of the seals 35 protruding contour is present, which affects the tightness of the filter element 27 in the filter housing (not shown).

FIG. 5 shows a section Z according to FIG. 4, the filter element 27 being shown in the state inserted into the filter housing 26. The filter housing 26 has a lower part 37 and an upper part 38. The filter element 27 is supported with its seal 35 on the lower part 37. The sensor wires 15 and the contacts 42 are arranged on the side opposite the lower part 37. The upper part 38 is sealingly connected to the lower part 37. In the upper part 38 there are voltage contacts 39 which directly touch the contacts 42 and thus put the sensor wires under tension. A power line 33 connects to the voltage contacts 39 and is connected to a voltage source (not shown).

FIG. 6 shows a section Z according to FIG. 4 in a variant, the filter element 27 being shown in the state that has been introduced into the filter housing 26. Components corresponding to FIG. 5 are provided with the same reference symbols. In this exemplary embodiment, the electrically conductive sensor wires 15 are made of aluminum, running along the folds 36, as a result of which they are in maximum contact with the filter medium 34. The filter element 27 separates a clean side 40 from a raw side 41 in the filter housing 26. The sensor wires 15 are arranged on the raw side 41, as a result of which they come into direct contact with the moisture and the moisture sensor 14 can promptly close the first raw air inlet (according to FIG. 1). In this exemplary embodiment, the contacts 42 of the sensor wires 15 are arranged inside the seal 35, as a result of which the contacts 42 are insulated all around. The voltage contacts 39 of the filter housing 26 penetrate into the seal 35 and pierce the contacts 42 of the sensor wires 15, as a result of which an electrical contact is generated between the contacts 42 and the voltage contacts 39.

FIG. 7 shows a section Z according to FIG. 4 in a variant, the filter element 27 being shown in the state that has been introduced into the filter housing 26. Components corresponding to FIG. 5 are provided with the same reference symbols. In this exemplary embodiment, the sensor wires 15 are woven through the filter medium 34, as a result of which the sensor wires 15 are in contact both with the clean side 40 and with the raw side 41. The contacts 42, which are completely enclosed by the seal 35, are connected to the sensor wires 15. The contacts 42 are designed as clamping contacts, as a result of which the voltage contacts 39 of the filter housing 39 penetrate into the seal 35 and penetrate into the contacts 42. In order to prevent errors when changing the filter, the filter element 27 is constructed symmetrically, as a result of which a connection between the voltage contacts 39 and the contacts 42 is also produced when the filter element 27 is rotated by 180 °.

FIG. 8 shows a filter element in a partial view, the moisture sensor 14 being arranged in a partial area of the filter element 27. The seal 35 is designed such that it surrounds the moisture sensor 14 and fixes it in its position. The sensor wires 15 are applied to a carrier 30 which is electrically insulating in the dry state and which can absorb water, as a result of which it becomes conductive. In this embodiment, the sensor wires are not in direct contact with the filter medium 34.

FIG. 9 shows a section Z according to FIG. 4 in a variant. The detection of moisture in the filter medium 34 is based on the transformer principle. In this embodiment, the filter medium 34 is a filter paper, into which an electrically conductive sensor wire 15 was cast during the manufacture of the filter paper. As shown in FIG. 10, the sensor wire 15 has two legs 43 running in parallel and a secondary winding region 44. The secondary winding area 44 has a diameter of approximately 10 to 20 mm.

On the one hand, a pot-shaped ferrite core 45 is placed on the filter medium 34. A ferrite disc 46 is arranged opposite the ferrite core 45 on the other side of the filter medium 34. The ferrite disk 46 and the ferrite core 45 consist of a material which is magnetically conductive at a higher frequency. This material is e.g. from the finest iron filings, which are cast in synthetic resin or plastic. The ferrite core 45 is pressed against the filter medium 34 by a spring 47. For this purpose, the spring is supported on the filter housing 26. The spring 47 is preloaded in such a way that the ferrite core 45 does not lift off the filter medium 34 even when shaken. A further electrical sensor wire 15 is arranged in the ferrite core 45. This sensor wire 15 has a primary winding area 48, the diameter of which essentially corresponds to the diameter of the secondary winding area 44. However, it is also conceivable for the diameters of the winding regions 44, 48 to be of different sizes. In other versions, the sensor wire 15 is integrated with the primary winding area 48 in the filter housing 26. The primary winding area 48 is connected to an AC voltage source (not shown), with which an AC voltage, e.g. with 50kHz. The alternating voltage in the sensor wire 15 with the primary winding region 48 generates an alternating magnetic field 49 in the ferrite core 45 in connection with the ferrite disk 46. The ferrite disc 46 serves to close the alternating magnetic field 49 and to minimize the leakage losses of the alternating magnetic field 49. It is advantageous here that the ferrite disc 46 has essentially the same outer diameter as the ferrite core 45.

The sensor wire 15 integrated in the filter medium 34 has no voltage supply, as a result of which, as long as the filter medium 34 is dry and electrically non-conductive, it does not change the alternating magnetic field. As soon as the filter medium 34 becomes moist and electrically conductive, a current flows in the sensor wire 15 with the secondary winding area 44, whereby it causes an increase in the current in the sensor wire 15 with the primary winding area 48. This current increase is recorded by an evaluation unit (not shown) and sends out a signal for closing the first raw air inlet 10 according to FIG. 1.

FIG. 10 shows a partial section along the section line A-A according to FIG. 9. Components corresponding to FIG. 9 are provided with the same reference symbols.

Claims (13)

1. Intake system for an internal combustion engine of an automotive vehicle, including a first unfiltered air inlet (10), a second unfiltered air inlet (11), a closing member (13) and a displacement unit (17),

   - wherein the second unfiltered air inlet (11) is disposed at a position which is protected against spray water and bilge water,

   - wherein the first unfiltered air inlet (10) and the second unfiltered air inlet (11 ) are connected in a communicating manner to a common line (12), and wherein the line (12) is connected in a communicating manner to the internal combustion engine,

   - wherein the second unfiltered air inlet (11) is closable in a first position with the closing member (13) and wherein the first unfiltered air inlet (10) is closable in a second position with the closing member (13),

   - wherein the closing member (13) is displaceable by means of the displacement unit (17), and wherein the displacement unit (17) is connected to a control means (32), by means of which the displacement unit (17) is activatable.

   - wherein the control means (32) is a moisture sensor (14), which is formed by at least two conductive sensor wires (15), wherein the sensor wires (15) are disposed at a spacing one relative to the other, wherein the moisture sensor (14) produces a signal output for controlling the displacement unit (17),

      characterised in that,

   - the intake system includes a filter element (27) with a filtering medium (34), whereby the filter element (27) is inserted into a filter housing (26) in such a manner that an unfiltered region (24) is sealingly separated from a filtered region (25), wherein the moisture sensor (14) is incorporated into the filter element (27).
2. Intake system according to claim 1, characterised in that the conductive sensor wires (15) are mounted on a support (30).
3. Intake system according to one of the previous claims, characterised in that the conductive sensor wires (15) of the moisture sensor (14) are directly connected to the filtering medium (34).
4. Intake system according to one of the previous claims, characterised in that the filter housing (26) has voltage contacts (39), by means of which the moisture sensor (14) is suppliable with voltage.
5. Intake system according to one of the previous claims, characterised in that the moisture sensor (14) has voltage supplying means (31), which are admitted in a seal (35), which extends around the filtering medium (34).
6. Intake system according to claim 5, characterised in that the voltage contacts (39) of the filter housing (26) are connected to the voltage supplying means (31) of the moisture sensor (14).
7. Intake system according to claim 6, characterised in that the voltage contacts (39) of the filter housing (26) penetrate into the seal (35) of the filter element (27).
8. Intake system according to claim 1, characterised in that the first sensor wire (15) has a primary winding region (48), which is disposed in a ferrite core (45), wherein the ferrite core (45) abuts against the filtering medium (34), and in that the second sensor wire (15) is inserted in a central region into the filtering medium (34), wherein the second sensor wire (15) has two parallel portions (43), against which a secondary winding region (44) abuts.
9. Intake system according to one of the previous claims, characterised in that a plurality of moisture sensors (14) are provided.
10. Intake system according to claim 9, characterised in that one of the moisture sensors (14) is disposed in a plane with the first unfiltered air inlet (10).
11. Intake system according to claim 9 or 10, characterised in that one of the moisture sensors (14) is disposed in the first unfiltered air inlet (10).
12. Intake system according to one of the previous claims, characterised in that the operability of the moisture sensor (14) is testable at the start-up of the internal combustion engine.
13. Intake system according to one of the previous claims, characterised in that the operability of the displacement unit (17) of the closing member (13) is checkable at the start-up of the internal combustion engine.