EP1213473A2 - Intake system - Google Patents

Abstract

An intake system for an internal combustion engine of a motor vehicle which includes a first unfiltered air intake (10) which is arranged at a location in the vehicle that is favorable for air intake, and a second unfiltered air intake (11) which is arranged at a location in the vehicle that is protected against road spray and splashes of water. The two unfiltered air intakes (10, 11) each open into a common line (12) which communicates with the internal combustion engine. In the first unfiltered air intake (10) there is a moisture sensor (14) which emits a signal when water enters the first unfiltered air intake (10). This signal actuates a drive member 23 which moves a flap 13 between first and second switching positions. In the first switching position, the flap 13 closes the second unfiltered air intake 11, so that no air can get into line 12 from the second unfiltered air intake 11. In the second position, the flap 13 closes the first unfiltered air intake 10, so that air gets into line 12 exclusively through the second unfiltered air intake 11.

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 claim 1.

From DE 196 13 860 it is an air intake filter device for a motor vehicle engine known, which has a pipe space, which with suction lines with a Main inlet and a secondary inlet is connected. There is also a locking device provided, which alternately close one suction line and the other suction line can open. The locking device is made with an actuating device moves the locking device in a motor vehicle immersed in water closes the main inlet and opens the secondary inlet. The actuator is operatively connected with a slide. The slider is in one, at its lower end arranged open tube, wherein it is sealed against the tube. The slider is operatively connected with a permanent magnet. The locking device is with another Permanent magnets operatively connected, the permanent magnet of the locking device is rotatably arranged to the permanent magnet of the actuator.

A disadvantage of this design is the considerable space required for the tube, which in the engine compartment is arranged. This cannot be done too small, otherwise the switching point of the arrangement cannot be precisely defined. Still responding this mechanical switching arrangement only when the vehicle is in a standing water dips. In the case of splash water, no pressure sufficient to switch is built up, causing water to enter the intake system and impair the function of the engine.

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

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 are brought together in a common line and this line with the internal combustion engine is communicating. Here, the two raw air inlets are also only brought together immediately before the internal combustion engine, whereby each raw air inlet has its own components such as its own filter element features. Each raw air inlet consists of an opening through which air enters the intake system can flow, and a line section which the opening with the line combines. The raw air inlets are with one or more closure elements closable, whereby either through the first raw air inlet or through the second Raw air intake air into the line communicating with the internal combustion engine arrives. The closure element closes the respective raw air inlet completely, thereby Air should only flow into the line through the unsealed raw air inlet can. The closure element can e.g. through a rotating body with corresponding openings are formed, which releases the first raw air inlet in an end position and in closes the first unfiltered air inlet in a second end position.

Through the line communicating with the internal combustion engine, the inflowing Air directed directly or indirectly to the internal combustion engine. The air becomes indirect to the internal combustion engine, the air can be pretreated e.g. dried or be cooled. If the air is directed directly to the internal combustion engine, there is none additional component in the line required.

The first raw air inlet is at a location in the motor vehicle which is advantageous for air intake arranged. Here, the front area is a preferred location because it is appropriate the vehicle speed, the air is pushed into the unfiltered air intake is, whereby the filling level of the cylinder is improved. Furthermore, it is in the front area Air drawn in is cooler than the air in the engine compartment. However, in the front area snow, ice, water spray or whipped water can also get into the first unfiltered air intake. Water drops of any size mixed with air are referred to as splash water, Splash water can e.g. whirled up from the road by a preceding vehicle or be generated by rain. The term blow water describes a larger amount of water, which e.g. occurs as a gush of water when crossing a river. The second raw air inlet is at a location in the motor vehicle which is less favorable for air intake arranged, this point is protected from splash and blow water. Preferred jobs for the arrangement of the second raw air inlet, e.g. the engine compartment or the ventilation system his.

A movement unit is provided for actuating the closure element, which is connected to a control. The movement unit can e.g. by an electric motor or a vacuum can be formed and can be activated with the control element, whereby the movement unit a rotational or translational movement executes, which moves the closure element into an end position and thus either the closes the first or the second raw air inlet. The control is through a Moisture sensor formed, which has a signal output for controlling the movement unit has, of course, the humidity sensor also for control can be used.

The moisture sensor can be set in such a way that it what the internal combustion engine already affects in its function, a signal to the Movement unit sends, through which the first raw air inlet is closed. at Another setting of the moisture sensor gives the signal to close of the first raw air inlet only when the moisture sensor is surrounded by water is. The signal from the moisture sensor can be sent both directly and via electronics, such as. the motor control to be sent to the movement unit. Once the the first dirty air inlet is closed by the closure element, the second dirty air inlet opened, whereby the internal combustion engine from the second raw air inlet sucked in air for combustion.

In an expedient embodiment of the invention, the closure element is a Flap. The flap can e.g. circular, oval or rectangular, so that it closes the second raw air inlet in a first position and in a second position Position closes the first raw air inlet. Here, the flap can be placed centrally on a Valve shaft can be arranged and by a rotary movement of the valve shaft be moved. In other versions, the valve shaft is in an edge area arranged and thus enables an interference-free raw air intake. For intrusion of water in the first raw air inlet, especially when immersed in water, to prevent the flap can have a circumferential seal. They are too Designs conceivable in which a first flap in the first raw air inlet and one second flap is arranged in the second raw air inlet, both flaps communicating are interconnected. As soon as the first flap changes position, the second flap is also moved, which always opens a raw air inlet and the other raw air inlet is closed. The communicating connection of the flaps can mechanically e.g. with a strut or electronically by a signal, which in particular from the moisture sensor.

According to a special embodiment, the flap has two corresponding to each other connected flap parts. These flap parts can be at a defined angle to each other be arranged, where they touch directly or by means of connecting elements can be rigidly connected. Here, the parallel arrangement of the flap parts to each other a special design. The flap parts can also locally be arranged separately and correspond to each other only via the movement unit. The flap parts can e.g. a circular, oval or rectangular cross section have, a flap part closes a raw air inlet. The flap parts can have a circumferential seal, which seals the raw air inlets are lockable. By using flap parts to close the unfiltered air inlets The unfiltered air inlets can be integrated into the joint in a variety of ways Line.

In an advantageous embodiment, the movement unit is a lifting magnet, which communicating with the moisture sensor. The solenoid can Carry out an axial or radial movement to move the closure element. As soon as the moisture sensor senses water, it sends a signal to the solenoid from which a movement of the solenoid and thus the change of position of the closure element causes. The solenoid reacts within a fraction of a Second on the signal, which closes the first raw air inlet before water penetrate and get to the internal combustion engine. As is known, lifting magnets have via an armature, a spring, a coil, a yoke and an electrical Connection.

In a special embodiment of the invention, the moisture sensor is in one Level arranged with the first raw air inlet. Here he can at one of the unfiltered air intake distant point, which is mainly in contact with water comes. The closure element is defined above the moisture sensor Arranged at a distance, creating a sufficient response time between sensing of water and closing the first raw air inlet remains, so that no water can penetrate. The moisture sensor is preferably at a location in the engine compartment arranged. As a result, the moisture sensor detects the ambient conditions in the engine compartment. When passing through water, the moisture sensor also dives the raw air inlet into standing water and immediately causes the closure of the first raw air inlet through the higher-level closure element. Through the Arrangement of the moisture sensor on the same level as the first raw air inlet, If the first raw air inlet is closed too early, arranged moisture sensor would be prevented.

Another embodiment of the invention provides that the moisture sensor in the first raw air inlet is arranged. Thus, the moisture sensor precisely detects the condition that prevails in the first raw air inlet. It causes the first to close Raw air intake through the closure element as soon as water in the first raw air intake penetrates. The closure element is arranged downstream of the moisture sensor the distance between the closure element and the moisture sensor such chosen is that after sensing the water there is still a sufficient reaction time remains, which closes the first raw air inlet before the water on the closure element can flow past and get to the internal combustion engine. Through the Arrangement of the moisture sensor in the first raw air inlet becomes the first raw air inlet only closed if water actually enters the first raw air inlet. The air is thus sucked in via the one that is cheaper for the internal combustion engine first unfiltered air inlet and only if there is actually water in the first unfiltered air inlet penetrates, the first unfiltered air inlet is closed and the air via the second unfiltered air inlet sucked.

According to an advantageous embodiment of the invention, the moisture sensor can be heated executed. For example, resistance heating can be used for this. It is however, it is also conceivable for the heat from adjacent components to heat the moisture sensor to use. By heating the moisture sensor, for example Snow or ice can be melted. Furthermore, the heating of the moisture sensor can be used to evaporate the adhering water drops.

An advantageous embodiment of the invention provides a moisture sensor, which as Conductivity sensor with two electrodes is in front. Once the electrodes with If water comes into contact, the conductivity of the conductivity sensor changes. The Structure of the conductivity sensor, in particular the distance between the electrodes is in accordance with the switching conditions, when the first raw air inlet is closed and the second raw air inlet is to be opened. The smaller the distance between the electrodes from each other, the earlier the electrodes are e.g. with one Water drops connected, whereby the conductivity sensor sends out a signal and the Movement unit for closing the first raw air inlet. Point If the electrodes are at a large distance from each other, a drop of water alone can Do not connect electrodes. Only after both electrodes in e.g. a Wasserfurt immersed the conductivity sensor sends the signal to close the first one Unfiltered air inlet. One version of the conductivity sensor has e.g. two electrodes, which consists of an insulating layer, e.g. Air, plastic or ceramic are separated. As soon as If there is water on the insulating layer and bridges it, the electrodes become conductively connected to each other, whereby the sensor signal is generated and the closure element is brought into the second position by means of the movement unit. ever the moisture sensor reacts according to how wide the insulating layer is formed even on single drops with splash water or only with splash water when the electrodes are completely surrounded by water.

It is advantageous that the moisture sensor has at least two electrically conductive Wires is formed, wherein the wires are arranged spaced apart. The electric Conductive wires are made of a material that has a low electrical Has resistance and is therefore a good electrical conductor, e.g. Metals or metal alloys. The wires arranged at a distance from one another can be parallel or run at an angle to each other.

According to a further embodiment of the invention, the electrically conductive wires are applied to a carrier, the wires embedded in the carrier or on the Carrier can rest. The carrier consists of a carrier material which is dry Condition the conductive wires are insulated. This material can be designed that it can absorb water and then become electrically conductive. Another one Design of the carrier, the carrier material can not absorb water, so the water is deposited as drops on the carrier. This drop of water bridges then the electrically insulating substrate and connects the wires together, thereby a current flow arises which causes the first raw air inlet to close.

In a further embodiment of the invention, the moisture sensor is a capacitance sensor, which has two spaced-apart capacitor plates. The capacitor plates are connected to an AC voltage source, creating an electrical Field with a defined field strength is generated. The field strength is known depending on the applied voltage and the distance of the capacitor plates from each other. The farther apart the capacitor plates are, the weaker they are is the electric field. The capacitance of capacitors depends on the area and the distance of the capacitor plates, as well as from the Permittivity number of the substance between the capacitor plates.

The capacitor plates have an electrically conductive material such as e.g. Metal on. This electrically conductive material can have a protective layer made of a non-conductive Material such as Plastic. The protective layer can e.g. a corrosion protection which completely encloses the capacitor plates, whereby the capacitor plates do not come into direct contact with water or air. The capacitor plates are connected to an evaluation unit in which the electrical field between the capacitor plates is evaluated. The evaluation unit measures the capacity of the Capacitor plates with high frequency AC voltage. Air has a permittivity number from about 1 to and water has a permittivity number of about 80. As soon as water Instead of air being sucked in, the permittivity number between the capacitor plates changes significantly, causing the evaluation unit to send a signal to the movement unit sends and the first raw air inlet is closed by the closure element.

The capacitance sensor can be set in such a way that it only works on water hammer if the permittivity between the capacitor plates changes significantly, responds. With other settings, even a small change in the permittivity number can sufficient to close the first unfiltered air intake.

The capacitor plates can be in parallel or anywhere in the motor vehicle be arranged in mirror image to each other. In preferred configurations, the capacitance sensor is arranged at the first raw air inlet, the capacitor plates being semicircular be formed and can enclose the first raw air inlet. By the use of a capacitance sensor can make a reliable statement which medium is currently being sucked in, with capacity sensors insensitive to dirt are.

An advantageous embodiment of the invention is a concentric structure of the capacitance sensor. Here, the capacitor plates are cylindrical, with an outer Capacitor plate encloses an inner capacitor plate. This concentric Capacity sensor can be arranged directly in the first raw air inlet, wherein the contour of the outer capacitor plate of the inner contour of the first raw air inlet equivalent. For fixing the inner capacitor plate in the outer capacitor plate can be a web or multiple webs can be provided, which the flow of Influence intake air very little. Furthermore, the webs can be made electrically insulating material, in particular the same material as the protection layer of capacitor plates. By using a concentric built-up capacitance sensor becomes a stable field between the capacitor plates generated, making the capacitance sensor insensitive to disruptive influences.

In a further embodiment of the capacitance sensor, the capacitor plates run within the first raw air inlet at an angle to each other, each condenser plate on the one hand touches the first line section and on the other hand centrally in the first raw air section are fixed. In this embodiment, the angle can be preferred 90 °, which means that four electrical fields can be generated and evaluated.

An advantageous embodiment of the invention provides for the arrangement of a plurality of moisture sensors in front. Here, e.g. two identical moisture sensors are provided be, the humidity sensors also in different places in the engine compartment can be arranged. This enables a switching logic to be set up. Farther can use moisture sensors with different principles or sensitivities be combined. Here, the moisture sensors can be placed side by side or can be arranged at different locations in the motor vehicle. With a possible Arrangement can e.g. a highly sensitive moisture sensor in the first raw air inlet and a less sensitive humidity sensor in the engine compartment below the be arranged first raw air inlet. This allows different switching variants be formed. As soon as the less sensitive moisture sensor is immersed in water, he can output the signal to close the first raw air duct, although the highly sensitive moisture sensor is not yet in contact with water. At a Another variant, both moisture sensors come into contact with splash water, which causes the insensitive moisture sensor does not yet send a signal, but the highly sensitive one Moisture sensor the signal for closing the closure element sending out.

It is advantageous that the functionality of the moisture sensor at the start of the Internal combustion engine is testable. As soon as the internal combustion engine is started there is a Sensor test that checks the functionality of the moisture sensor so that the Moisture sensor is also functional if necessary. To the operator of the internal combustion engine The moisture sensor can indicate the state of the moisture sensor e.g. be connected to a control lamp which, after the sensor test, if the sensor is working correctly goes out. In the case of a negative sensor test in which If the moisture sensor does not work properly, the indicator light can e.g. flash or shine constantly. Thus, the operator is informed that the intake system is not works properly and if there is water, the first raw air intake may not be closed, 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 starting the internal combustion engine. Here, the movement unit and the closure element with each start the internal combustion engine moves, making all parts functional and not when needed by e.g. Corrosion is immobile. Checking the movement unit and the closure element can e.g. be displayed with an indicator light and only go out after successful movement.

These and other features of preferred developments of the invention go beyond from the claims also from the description and the drawing, the individual characteristics individually or in groups in the form of sub-combinations be implemented in the embodiment of the invention and in other fields and can represent advantageous and protectable versions for which here Protection is claimed.

drawing

Figur 1

ein Ansaugsystem,

Figur 2

ein Ansaugsystem in einer weiteren Ausführung und

Figur 3

ein Schaltdiagramm,

Figur 4

einen Leitfähigkeitssensor,

Figur 5

einen Feuchtigkeitssensor mit mehreren Elektroden,

Figur 6

ein Ansaugsystem mit einem Kapazitätssensor,

Figur 7

ein Ansaugsystem mit einem Kapazitätssensor,

Figur 8

einen Schnitt A-A gemäß Figur 7

Figur 9

einen Ausschnitt aus einem Ansaugsystem.

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

Figure 1

an intake system,

Figure 2

a suction system in a further version and

Figure 3

a circuit diagram,

Figure 4

a conductivity sensor,

Figure 5

a moisture sensor with several electrodes,

Figure 6

an intake system with a capacity sensor,

Figure 7

an intake system with a capacity sensor,

Figure 8

a section AA according to FIG. 7

Figure 9

a section of an intake system.

Description of the embodiments

In Figure 1, an intake system is shown schematically. The intake system has one 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 to an internal combustion engine (not shown) leads. The first raw air inlet 10 is designed as a separate component, which is sealingly connected to the line 12. In other versions, the first and the second raw air inlet 10, 11 are made in one piece with the line 12. The intake system has a flap 13 which, depending on the position, the first raw air inlet 10 or the second raw air inlet 11 closes.

In a first position, the flap 13 closes the second raw air inlet 11, thereby the intake air enters the intake system through the first unfiltered air inlet 10 and is fed to the internal combustion engine. This first position is the basic position since the first raw air inlet 10, which creates more favorable conditions for the internal combustion engine. A deviation from the first position only occurs if through the first unfiltered air inlet 10 Water or snow enters the intake system.

To determine whether water or snow can enter the intake system, a Moisture sensor 14 is provided, which is connected to a vacuum box 15. As soon as the moisture sensor 14, which is designed as a conductivity sensor, with If water or snow comes into contact, its conductivity changes and it becomes a Signal from the moisture sensor 14 via a connecting line 16 to the vacuum box 15 sent. The vacuum can 15 generates a movement through the signal, through which the flap 13 moves to a second position (shown in dash-dot lines) becomes. In this second position, the first raw air inlet 10 is closed and the second raw air inlet 11 opened. The flap 13, which has a flap shaft 17, is connected to the vacuum box 15, whereby the valve shaft 17 is rotatory is moved and thereby the flap 13 from the first position to the second position (shown in broken lines) moved.

The first raw air inlet 10 is through a first opening 18 with a, to the first opening 18 subsequent first line section 19 is formed. The moisture sensor 14 is arranged in such a way that no water flows past the flap 13 into the line 12 has arrived. The second raw air inlet 11 is through a second opening 20 and one second line section 21 is formed. The second opening 20 is at an injection and splash-proof location in the motor vehicle, which is above the first opening 18 is located. The line sections 19, 21 can be any space curves follow in the motor vehicle, whereby the intake system fits into the engine compartment can be.

A variant of the intake system is shown in FIG. Corresponding to Figure 1 Components are provided with the same reference symbols. In this embodiment the moisture sensor 14 in the first raw air inlet 10 in the region of the first opening 18 arranged. The flap 13 for closing the first raw air inlet 10 is included a defined distance A to the moisture sensor 14 in the first line section 19 arranged. The distance A is designed so that the water during the Response time between the detection of water by the moisture sensor 14 and the closing of the first unfiltered air inlet 10 passes further into the first Raw air inlet 10 can penetrate without entering the line 12, which corresponds with the internal combustion engine is connected to arrive. Until the water at flap 13, which forms the transition to the line 12 arrives, the flap 13 must be closed his. The water can thus in the second position (dash-dotted lines) when the Flap 13 closes the first unfiltered air inlet 10, at most as far as flap 13, but do not get into line 12.

In this embodiment, the flap 13 has two flap parts 22, the Flap parts 22 are rigidly connected together. In the first position one closes of the flap parts 22, the second raw air inlet 11. In the second position (dash-dotted lines shown), the other flap part 22 closes the first raw air inlet 10 and the second raw air inlet 11 is released. The flap 13 is with a solenoid 23rd moved (the solenoid is shown rotated by 90 °).

The line 12 has a raw area 24 and a clean area 25. Between the A filter housing 26 is arranged in the raw area 24 and the clean area 25, in which a filter element 27 is introduced sealingly, whereby the clean area 25 seals the raw area 24 is separated. Furthermore, a second moisture sensor is in the filter housing 26 28 arranged, which monitors the intake air in the filter housing 26. This second moisture sensor 28 is a conductivity sensor with two electrodes 29, which are arranged parallel to each other. As soon as this second humidity sensor 28 which e.g. more sensitive to moisture e.g. Splashing water reacts as the first moisture sensor 14, generates a signal that water enters the filter housing 26 has penetrated, the solenoid 23 can also be activated, whereby the first raw air inlet 10 is closed by the flap 13.

The air cleaned by the filter element 27 becomes a in the clean area 25 of the line 12 Intake air distributor 30 supplied. The air supply of the intake air distributor 30 can by means of a throttle valve 31 in accordance with the operating states of the internal combustion engine be regulated.

A circuit diagram is shown in FIG. This circuit diagram represents the temporal Process in the detection of water in the intake system. The time axis runs horizontal and the voltage axis vertical. There are five curves in the circuit diagram shown. The curve I describes the voltage profile of the moisture sensor 14, the Curve II represents the switching signal of the moisture sensor 14, which corresponds to curve III the control signal of the movement unit, curve IV describes the movement of the movement unit and curve V represents the position of the flap 13. As long as none Water in contact with the moisture sensor 14 (e.g. according to one of Figures 1, 2, 4) has come, the flap 13 (according to one of Figures 1, 2) is in its first Position. At a, the moisture sensor 14 has come in contact with water, causing his tension changes. A switching signal b generated, which by the signal output of the moisture sensor 14 to the movement unit is directed. At c there is the control signal for the movement of the movement unit and the movement unit of motion begins at d. The movement is completed at e, whereby the flap 13 completely closes the first raw air inlet 10. From water detection a to closed first unfiltered air inlet 10 at e passes a reaction time R which is shorter than one second. With fast components response times of a few milliseconds can be realized, whereby even small distances A between the moisture sensor 14 and the flap 13 are sufficient to prevent water from entering line 12.

FIG. 4 shows a moisture sensor 14 which is designed as a conductivity sensor is. The conductivity sensor has two electrodes 29 which are insulated 32 are separated. Furthermore, the moisture sensor 14 has evaluation electronics 33, which is integrated in a sensor housing 34. Via a signal output 35 signals from the evaluation electronics 33 to the flap 13 (according to FIG. 1 or 2) be directed.

Once the annular insulation 32 is at least partially surrounded by water the electrodes 29 are conductively connected to one another. Only a small drop of water forms one Bridging the insulation 32, the conductivity of the changes Moisture sensor 14 less than a completely surrounded by water Moisture sensor 14. The moisture sensor can thus be set in such a way that the first unfiltered air inlet 10 (not shown) with splash water or only with Water is fired.

FIG. 5 shows a moisture sensor 14 with several electrodes 29. With this In the exemplary embodiment, the moisture sensor 14 has three electrode pairs 36 different electrode spacing D, the electrodes 29 exclusively by the air are isolated from each other. As soon as water bridges the electrode gap D, water is sensed. All three electrode pairs 36 are on the same sensor housing 34 arranged. The values of the three electrode pairs 36 are in the same evaluation electronics 33, which is arranged in the sensor housing 34, processed, one Switching logic is stored. Once the first pair of electrodes 36, which is the smallest Has electrode distance D, senses water and the other two pairs of electrodes 36 do not sense water, it is splashing water. Sensing all three pairs of electrodes 36 water, it is blow water, e.g. when crossing one Water ford. Depending on when the first raw air intake (according to one of Figures 1 or 2) the results of the electrode pairs 36 are to be linked and output as a signal to the movement unit (not shown).

A suction system is shown in perspective view in FIG. The intake system has a first unfiltered air inlet 10, a second unfiltered air inlet 11 and a line 12, which is correspondingly connected to an internal combustion engine (not shown) on. The first raw air inlet 10 has a first opening 18 through which air into the Intake system can flow and a first line section 19, which is the first Opening 18 connects to line 12. The second raw air inlet 11 has a second one Opening 20 and a second line section 21, wherein the second line section 21 connects the second opening 20 to the line 12. The cross section of the second raw air inlet 11 is smaller than the cross section of the first unfiltered air inlet 10, as a result of which the second unfiltered air inlet 11 can be designed so that it cannot be closed. The air is always through sucked the inlet with the lower air resistance, which means even with an unlocked one second unfiltered air inlet 11 the air through the opened first unfiltered air inlet 10 is sucked. Only when the first unfiltered air inlet 10 is closed the air is sucked in through the second dirty air inlet 11. In this embodiment the first raw air inlet 10 is made in one piece with the line 12, the first Raw air inlet 10 merges seamlessly into line 12. To separate line 12 from A flap 13 is provided on the first unfiltered air inlet 10, which flap 13 Valve shaft 17 is arranged. The flap shaft 17 is with a rotary flap adjuster 37 connected, which rotates the valve shaft 17. The second raw air intake 11 opens into the line 12 behind the flap 13, as seen in the flow direction.

A moisture sensor 14 is arranged on the first unfiltered air inlet 10 two capacitor plates 38 is formed. The capacitor plates 38 are curved, with the first line section 19 axially and radially in a partial area umschießen. Furthermore, the capacitor plates 38 are arranged opposite one another, whereby an electric field 39 is generated. Both capacitor plates 38 have via a voltage connection 40 in each case. The voltage connections 40 are connected to a Evaluation unit 41 connected. In the evaluation unit 41 this is done by the capacitor plates 38 generated electric field 39 evaluated. As soon as water in the first The untreated air inlet 10 penetrates, the electrical field 39 and the evaluation unit change 41 outputs a signal which is sent via a connecting line 16 to the Rotary flap adjuster 37 is guided and a movement of the rotary flap adjuster 37 causes the flap 13 to move to a closed position (not shown) becomes. The evaluation unit 41 measures with a higher-frequency AC voltage, in particular an AC voltage in the range of 10-50 kHz the complex resistance of the electric field 39.

FIG. 7 shows a suction system in a perspective view. Corresponding to FIG. 6 Components are provided with the same reference numerals in this exemplary embodiment the first dirty air inlet 10 and the second dirty air inlet 11 are made in one piece, the raw air inlets 10, 11 are formed by a pipe 42, in which on the one hand the first raw air inlet 10 with its first first opening 18 and on the other hand the second raw air inlet 11 is arranged with its second opening 20. Line 12, which is communicatively connected to an internal combustion engine (not shown), opens into a control area 43 in this tube 42. The control area 43 is by the defines two end positions of the flap 13, the flap 13 sealingly in the tube 42 is introduced. In the first end position (position x), the flap 13 closes the second raw air inlet 11, whereby only air that passes through the first raw air inlet 10 has entered the intake system. In the second end position (Position y) (dash-dotted lines), the flap 13 closes the first raw air inlet 10, whereby only air, which was sucked in from the second dirty air inlet 11 into the Line 12 arrives. The flap 13 is designed as a slide, whereby a translational Movement to move the flap position is required. This is a Push rod 44 on the one hand with the flap 13 and on the other hand with a Movement unit (not shown) connected. The movement unit can e.g. on Solenoid or an electric motor.

In this embodiment, the humidity sensor 14, which is in the first Raw air inlet 10 is arranged by two concentrically arranged condenser plates 38 formed. The first capacitor plate 38 is hollow-cylindrical, whereby it bears on the outside on the first line section 19. Furthermore, the first encloses Capacitor plate 38, the second capacitor plate 38, which is cylindrical. For fixing the second capacitor plate 38 in the first capacitor plate 38 are Crosspieces 45, which are arranged at a 90 ° angle to one another, are provided. The webs 45 consist, at least partially, of an electrically insulating material, so that between no direct charge exchange can take place in the capacitor plates 38. Both capacitor plates 38 each have a voltage connection 40, by means of which they are connected the evaluation unit 41 are connected. That between the first capacitor plate 38 and the second capacitor plate 38 generated electric field 39 is in the evaluation unit 41 evaluated. As soon as water has entered the first unfiltered air inlet 10 , the electric field 39 changes between the two capacitor plates 38, whereby the evaluation unit 41 sends a signal to the Movement unit (not shown) sends, whereby the flap 13 is moved and the closes first raw air inlet 10.

FIG. 8 shows a section along the section line A-A according to FIG. 7, the left and right half of the picture show different configurations.

On the left half of the picture, the first capacitor plate 38 is circular in cross section educated. It is made of metal and lies directly on the first line section 19, which is made of plastic. The second capacitor plate 38 is in cross section circular and made of plastic webs 45 within the first Capacitor plate 38 arranged. The webs 45 are dimensioned such that they are one form the lowest possible flow resistance, but the second capacitor plate 38 fix in their position. The two capacitor plates 38 have an insulating layer 46 made of plastic, the insulating layer 46 in this embodiment Web 45, which forms the second capacitor plate 38 fix in position.

On the right half of the picture, the capacitor plates 38 are at 90 ° to each other arranged, with all capacitor plates 38 connected to the first line section 19 and are fixed centrally in the first unfiltered air inlet 10. The electrical Field 39 is arranged at an angle to each other Capacitor plates 38 generated.

FIG. 9 shows a section from an intake system. Corresponding to FIG. 6 Components are provided with the same reference symbols. In this embodiment the first unfiltered air inlet 10 has a rectangular cross section 50. The Capacitor plates 38 are parallel to one another outside the first line section 19 arranged, whereby the electric field 39 can be easily evaluated.

Claims (12)

Intake system for an internal combustion engine of a motor vehicle, comprising a first unfiltered air inlet (10), a second unfiltered air inlet (11), a closure element (13) and a movement unit, the second unfiltered air inlet (11) being arranged at a location protected from splashing water and splash water, wherein the first unfiltered air inlet (10) and the second unfiltered air inlet (11) are brought together in a common line (12), the line (12) being communicatively connected to the internal combustion engine, wherein the second unfiltered air inlet (11) can be closed with the closure element (13) in a first position and the first unfiltered air inlet (10) can be closed with the closure element (13) in a second position, wherein the closure element (13) is movable with the movement unit, and wherein the movement unit is connected to a control element by means of which the movement unit can be activated, characterized in that
the control element is a moisture sensor (14) which has a signal output for controlling the movement unit. Intake system according to claim 1, characterized in that the moisture sensor (14) is arranged in one plane with the first raw air inlet (10). Intake system according to one of the preceding claims, characterized in that the moisture sensor (14) is arranged in the first raw air inlet (10). Intake system according to one of the preceding claims, characterized in that the moisture sensor 14 is heatable. Intake system according to one of the preceding claims, characterized in that the moisture sensor (14) is a conductivity sensor. Intake system according to one of the preceding claims, characterized in that the moisture sensor 14 is formed by at least two electrically conductive wires which are arranged at a distance from one another. Intake system according to claim 6, characterized in that the electrically conductive wires are applied to a carrier. Intake system according to one of claims 1 to 4, characterized in that the moisture sensor (14) is a capacitance sensor. Intake system according to claim 8, characterized in that the capacitance sensor is concentric. Intake system according to one or more of the preceding claims, characterized in that a plurality of moisture sensors (14) are provided. Intake system according to one of the preceding claims, characterized in that the functionality of the moisture sensor (14) can be tested when the internal combustion engine is started. Intake system according to one of the preceding claims, characterized in that the functionality of the movement unit and the closure element (13) can be checked when the internal combustion engine starts.

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