DE102014200699A1 - Low-pressure EGR valve - Google Patents

Abstract

The invention relates to a low-pressure EGR valve (1) which is equipped with a fresh air inlet (2), an exhaust gas inlet (3) and outlet (4). According to the invention, a connection surface (6) located between the outlet (4) and the exhaust gas inlet (3) is shaped such that condensate flows from the outlet (4) to the exhaust gas inlet (3) during normal use of the low-pressure EGR valve (1) , A second aspect of the invention relates to a motor vehicle having an internal combustion engine, an air filter, a compressor, a low-pressure exhaust gas recirculation and a low-pressure EGR valve (1) according to the invention connected to the air filter, the low-pressure exhaust gas recirculation and the compressor.

Description

The invention relates to a low-pressure EGR valve for a motor vehicle with an internal combustion engine and a motor vehicle with such a low-pressure EGR valve.

The emissions of motor vehicles are subject to legal provisions with the aim of reducing the environmental impact of motor vehicle traffic. This applies in particular to the emission of particulate matter such as soot particles and nitrogen oxides. A common approach to reduce nitrogen oxide emissions is to add some of the exhaust gas produced by the combustion of the fuel in the engine to the combustion air for the engine so as to lower the combustion temperature and to burn the fuel without excess oxygen. This technique known as exhaust gas recirculation or exhaust gas recirculation (EGR) can usually be carried out at high or low pressure, ie before (high pressure EGR) or after (low pressure EGR) passing of an exhaust gas turbine and / or exhaust aftertreatment devices , Combinations of high pressure and low pressure EGR may also be provided.

For exhaust gas recirculation, exhaust gas is taken from the exhaust gas stream of the internal combustion engine through a branch and mixed with the fresh air via an EGR valve, thus generating the combustion air for the internal combustion engine. In this case, usually the mixing ratio between fresh air and exhaust gas can be influenced by the EGR valve in order to allow suitable mixing ratios for different driving conditions. For example, it can be provided to interrupt the return of exhaust gas at a very high engine power, because much fuel is burned here and the largest possible amount of oxygen to be supplied to the combustion air. However, it may also be provided to mix in a high proportion of exhaust gas at low engine power in order to carry out the combustion of the fuel without excess oxygen.

The object of the invention is to introduce an improved low-pressure EGR valve.

The invention introduces a low pressure EGR valve equipped with a fresh air inlet, an exhaust gas inlet and an outlet. According to the invention, a connection surface located between the outlet and the exhaust gas inlet is shaped such that condensate flows from the outlet to the exhaust gas inlet in the intended use of the low-pressure EGR valve.

The outlet of the low-pressure EGR valve is intended to be connected to a compressor which compresses the combustion air for the internal combustion engine prepared from the fresh air and the recirculated exhaust gas in variable mixing ratios.

The water vapor contained in the recirculated exhaust gas can condense in particular at low ambient temperatures by the cooling in the contact with the fresh air supplied in the low-pressure EGR valve through the fresh air inlet. The condensed water collects in the low pressure EGR valve and may even freeze. The compressor, which is connected to the outlet in the intended use of the low-pressure EGR valve, contains a compressor wheel which rotates very rapidly and draws in the recirculated exhaust gas and the fresh air. The invention is based on the knowledge and includes this that the compressor wheel can be damaged when water droplets or even ice particles are sucked in and hit the compressor wheel. The low pressure EGR valve of the invention has the advantage that condensed water, in the proper use of the low pressure EGR valve, can flow away from the outlet and drain through the exhaust gas inlet from the low pressure EGR valve. The water can then be discharged, for example, via the exhaust tract and discharged to the environment.

As intended use is to be understood here that the low-pressure EGR valve installed in a motor vehicle and the motor vehicle is arranged on a flat road. According to the invention, the bonding surface is shaped such that there is a gradient between the outlet and the exhaust gas inlet under these conditions, so that the condensate can flow away from the outlet to the exhaust gas inlet. When used as intended, the outlet is thus above the exhaust gas inlet.

In particular, an abscissa passing through the outlet and the fresh air inlet and an ordinate crossing the abscissa and passing through the exhaust inlet may form a coordinate system. The interface then has a waveform with respect to the coordinate system that is monotonically decreasing from the outlet to the exhaust inlet. The monotonically falling curve of the connection surface causes the condensate to flow to the exhaust inlet and does not adhere to depressions or the like on the way.

The exhaust gas inlet is preferably designed to discharge the condensate from the low-pressure EGR valve. However, the condensate can only go away from the outlet Exhaust gas inlet are passed to be evaporated there by the usually warm recirculated exhaust gas and transported away with the combustion air. This is useful, for example, if the low-pressure EGR valve has to be positioned due to boundary conditions such that a drain of the condensate from the low-pressure EGR valve, for example via the exhaust due to a lack of gradients can not be realized.

The low-pressure EGR valve preferably has at least one throttle device for influencing a fresh air quantity flowing through the fresh air inlet and an exhaust gas quantity flowing through the exhaust gas inlet. The throttle device may be configured to close the exhaust inlet in a closed position. The throttle device may further include a shield configured to at least partially shield, in the closed position, an environmental region around the exhaust outlet from a gas flow from the fresh air inlet to the outlet. In the closed position (and positions of the throttle device in which the exhaust gas inlet is slightly opened), the largest amount of fresh air flows into the low pressure EGR valve, so that the risk of condensation in the low pressure EGR valve is greatest , If condensate has already formed, this has expired due to the shaping of the connection surface in the direction of the exhaust gas inlet, where it is shielded by the shield from the gas flow flowing entirely or mainly from the fresh air inlet to the outlet, so that there is no danger of drops or ice particles be sucked from the so-shielded condensate in the connected via the outlet with the low-pressure EGR valve compressor.

Particularly preferably, the shield is a throttle valve, which is also designed to influence the fresh air flow flowing through the fresh air inlet. The throttle valve may, for example, be pivotable about a shaft arranged between the exhaust inlet and the fresh air inlet, so that the throttle flap continues to cover the exhaust gas inlet and shield the latter when the fresh air inlet is opened. This arrangement of the shaft has the additional advantage that due to the lower lever length of the exhaust inlet with frozen condensate can be opened by applying a smaller force than when the condensate completely or partially on the opposite side seen from the shaft, so the outlet side facing , the exhaust inlet would be frozen.

Preferably, the low-pressure EGR valve of the invention is designed as a so-called combination valve, in which opened by means of only one actuator simultaneously the fresh air inlet and the exhaust inlet closed or closed the fresh air inlet and the exhaust gas inlet can be opened. However, it is also possible to provide the low-pressure EGR valve with a respective throttle valve for the exhaust gas inlet and for the fresh air inlet, each of which is pivotable about its own shaft and movable by its own actuator. Such an arrangement is more complicated than a combination valve, but offers greater freedom in determining the mixing ratio between fresh air and recirculated exhaust gas.

In particularly preferred embodiments of the low-pressure EGR valve according to the invention, a central axis of the exhaust gas inlet in the intended use of the low-pressure EGR valve in a projection on a vertical sectional plane through the low-pressure EGR valve in such a horizontal line through the outlet and the fresh air inlet cross that the central axis and the horizontal line form an acute angle facing the joint surface. By this particular arrangement, the exhaust inlet points away from the outlet, causing the condensate to collect predominantly on the side of the exhaust inlet remote from the outlet. This increases the distance between the outlet and the collected condensate, reducing the risk of condensate or ice particles being drawn into the outlet. These embodiments are particularly advantageous when the low-pressure EGR valve is temporarily operated with the exhaust gas inlet closed, so that the condensate can not be removed from the low-pressure EGR valve.

In this case, an opening extending from an outlet-side of the opening to a side of the opening facing away from the outlet can be provided around an opening of the exhaust gas inlet. This depression simplifies the drainage of the condensate to the opposite side of the opening of the exhaust gas inlet and may be formed, for example, as a groove.

Preferably, the recess extends in a closed contour, for example annularly, around the opening of the exhaust gas inlet. The closed contour runs on both sides of the opening and can thus dissipate a larger amount of condensate. In addition, the recess on both sides of the opening of the exhaust gas inlet from the walls of the low-pressure EGR valve can receive and drain condensate. The recess may, for example, extend in a plane to which the central axis of the exhaust gas inlet forms a normal.

A second aspect of the invention relates to a motor vehicle with an internal combustion engine, a Air filter, a compressor, a low-pressure exhaust gas recirculation and connected to the air filter, the low-pressure exhaust gas recirculation and the compressor according to the invention low-pressure EGR valve.

The invention will be explained in more detail with reference to illustrations of exemplary embodiments. Show it:

1 a first embodiment of a low-pressure EGR valve according to the invention; and

2 A second embodiment of a low-pressure EGR valve according to the invention.

1 shows a first embodiment of a low-pressure EGR valve according to the invention 1 that has a fresh air intake 2 , an exhaust inlet 3 and an outlet 4 has. In the embodiments shown, the low pressure EGR valve 1 a housing 19 into which the exhaust inlet 3 empties. The outlet 4 is in a lateral recess in the housing 19 taken in and there by a seal 20 sealed gas-tight. The fresh air intake 2 is as part of an insert or insert 18 formed on a wall of the interior of the low pressure EGR valve 1 forms and on the housing 19 for example, by bolts or similar fasteners can be attached. This structure has the advantage that the insert 18 can be removed, reducing the interior of the low-pressure EGR valve 1 during manufacture or for maintenance or repair can be made easily accessible. The housing 19 is preferably as a cast piece of metal and the insert 18 made of plastic. However, many alternative construction variants are possible, so that the invention is not as in the in the 1 and 2 shown housing construction is restricted.

In the interior of the low-pressure EGR valve 1 is a throttle device 5 for influencing a through the fresh air inlet 2 incoming fresh air and one through the exhaust inlet 3 incoming exhaust gas disposed. The throttle device 5 includes in the example shown a first throttle 9 , which is formed by the fresh air inlet 2 to influence inflowing fresh air quantity. In 1 is the throttle device 5 in a position where the fresh air intake 2 maximum open and the exhaust inlet 3 closed is. The through the exhaust inlet 3 inflowing exhaust gas is through a second throttle 16 influenced, in the illustrated embodiments, for example, an opening 12 the exhaust inlet 3 closes, so that no exhaust gas can flow into the low-pressure EGR valve. The two throttle valves 9 and 16 are through a connector 17 but it is also conceivable to provide a single throttle valve, both the fresh air intake 2 , as well as the exhaust inlet 3 in opposite positions of the throttle device 5 can close. Likewise, in all embodiments of the invention, two throttle valves 9 and 16 be provided, which can be independently pivot, so that through the fresh air inlet 2 incoming fresh air and through the exhaust inlet 3 Inflowing exhaust gas can be influenced independently. In the embodiment shown has the throttle device 5 a wave 15 to the the butterfly valves 9 and 16 are pivotable by an actuator, not shown.

Intended use is the low-pressure EGR valve 1 aligned so that the exhaust inlet 3 below and the fresh air intake 2 and the outlet 4 face each other laterally. According to the invention is a connection surface 6 between the outlet 4 and the exhaust inlet 3 It is shaped so that condensate from the outlet 4 to the exhaust inlet 3 flows. The condensate may optionally be from the exhaust inlet 3 received and so from the low pressure EGR valve 1 be derived. For example, the connection surface 6 be formed so that it has a curve which, with respect to a coordinate system of an abscissa 7 and an ordinate 8th monotonically decreasing, preferably strictly monotone decreasing.

The first throttle 9 the throttle device 5 is preferably shaped and arranged so that it is wide open fresh air inlet 2 the area around the opening 12 the exhaust inlet 3 if possible from one of the fresh air intake 2 to the outlet 4 flowing gas stream shields, leaving condensate in the area around the opening 12 the exhaust inlet 3 collected or frozen there, not with the gas flow into the outlet 4 is carried away.

2 shows a second embodiment of a low-pressure EGR valve according to the invention 1 , The same reference numerals designate the same or functionally similar parts, so that what is said for the first embodiment also applies to the second embodiment, unless expressly deviated from. The essential distinguishing feature of the second embodiment of the invention is that the exhaust gas inlet 3 in the low pressure EGR valve 1 arranged so that the opening 12 the exhaust inlet 3 from the outlet 4 away and towards the fresh air intake 2 has. As a result, when the exhaust gas inlet is operationally closed 3 the resulting condensate on the from the outlet 4 opposite side of the exhaust inlet 3 and thus at one farther from the outlet 4 Collects distant place. As a result, the condensate in the liquid or frozen state with reduced probability in the outlet 4 sucked where it could damage the compressor. Will the exhaust inlet 3 reopened, the condensate can through the exhaust inlet 3 drain or through through the exhaust inlet 3 incoming warm exhaust gas stream evaporated and transported away with the combustion air.

In 2 also shown is an optional indentation 13 , which exemplifies a ring around the opening 12 the exhaust inlet 3 in the wall of the housing 19 is provided, wherein the recess in a plane 14 runs on the one central axis 10 the exhaust inlet 3 forms a surface normal. However, according to the conditions of each case, other shapes are for such recess 13 possible. The central axis 10 the exhaust inlet 3 forms due to the from the outlet 4 remote orientation of the exhaust inlet 3 with the abscissa 7 , which in the intended use of the low-pressure EGR valve 1 should be arranged horizontally, an acute angle 11 ,

The depression 13 of the second embodiment of the invention has the advantage that condensate, the depression 13 on the outlet 4 facing side of the opening 12 reached to the opening 12 if necessary through the second throttle 16 closed, around to the outlet 4 opposite side of the opening 12 the exhaust inlet 3 passes. The depression 13 can be shaped on the opposite side so that when the second throttle is open 16 the entire condensate from the depression 13 in the exhaust inlet 3 can drain off, which can be achieved, for example, that the depression 13 on the from the outlet 4 opposite side of the opening 12 the exhaust inlet 3 is arranged at its lowest point in the intended use above or gleichauf with the located on the opposite side upper edge of the exhaust gas inlet.

The invention has the advantage that the risk of damaging the compressor wheel of a compressor connected to the low-pressure EGR valve by liquid or frozen condensate is lowered by the condensate from the outlet of the low-pressure EGR valve, to which the compressor is connected , away and optionally through the exhaust inlet is derived.

Although the invention has been further illustrated and described in detail by way of embodiments of preferred embodiments, the invention is not limited by the disclosed examples. Variations of the invention may be derived by those skilled in the art from the illustrated embodiments without departing from the scope of the invention as defined in the claims.

LIST OF REFERENCE NUMBERS

1

 Low-pressure EGR valve

2

 Fresh air inlet

3

 exhaust inlet

4

 outlet

5

 throttling device

6

 interface

7

 abscissa

8th

 ordinate

9

 first throttle

10

 central axis

11

 acute angle

12

 opening

13

 deepening

14

 level

15

 wave

16

 second throttle

17

 joint

18

 insert

19

 casing

20

 poetry

Claims (11)

A low-pressure EGR valve ( 1 ) with a fresh air inlet ( 2 ), an exhaust inlet ( 3 ) and an outlet ( 4 ), characterized in that one between the outlet ( 4 ) and the exhaust inlet ( 3 ) connection surface ( 6 ) is shaped so that in the intended use of the low-pressure EGR valve ( 1 ) Condensate from the outlet ( 4 ) to the exhaust inlet ( 3 ) flows. The low-pressure EGR valve ( 1 ) of the preceding claim, wherein one through the outlet ( 4 ) and the fresh air intake ( 2 ) extending abscissa ( 7 ) and one the abscissa ( 7 ) and through the exhaust inlet ( 3 ) ordinate ( 8th ) form a coordinate system and in which the connection area ( 6 ) has a curve with respect to the coordinate system, which from the outlet ( 4 ) to the exhaust inlet ( 3 ) is monotonically decreasing. The low-pressure EGR valve ( 1 ) of one of the preceding claims, wherein the exhaust gas inlet ( 3 ) is formed, the condensate from the low-pressure EGR valve ( 1 ). The low-pressure EGR valve ( 1 ) of one of the preceding claims, with at least one throttle device ( 5 ) for influencing a through the fresh air inlet ( 2 ) incoming fresh air quantity and through the exhaust gas inlet ( 3 ) incoming exhaust gas. The low-pressure EGR valve ( 1 ) of the preceding claim, wherein the throttle device ( 5 ) is formed, in a closed position, the exhaust gas inlet ( 3 ), and in which the throttle device ( 5 ) a shield ( 9 ), which is designed, in the closed position one around the exhaust gas outlet ( 3 ) arranged surrounding area of a gas flow from the fresh air inlet ( 2 ) to the outlet ( 4 ) at least partially shield. The low-pressure EGR valve ( 1 ) of the preceding claim, wherein the shield ( 9 ) a throttle valve ( 9 ), which is also formed by the fresh air inlet ( 2 ) to influence incoming fresh air quantity. The low-pressure EGR valve ( 1 ) of one of the preceding claims, wherein a central axis ( 10 ) of the exhaust gas inlet ( 3 ) in the intended use of the low-pressure EGR valve ( 1 ) in a projection onto a vertical sectional plane through the low-pressure EGR valve ( 1 ) one through the outlet ( 4 ) and the fresh air intake ( 2 ) horizontal line ( 7 ) such that the central axis ( 10 ) and the horizontal line ( 7 ) one of the connection surface ( 6 ) facing acute angle ( 11 ) form. The low-pressure EGR valve ( 1 ) of the preceding claim, in which an opening ( 12 ) of the exhaust gas inlet ( 3 ) one of the outlet ( 4 ) facing side of the opening ( 12 ) to an outlet ( 4 ) facing away from the opening ( 12 ) deepening ( 13 ) is provided. The low-pressure EGR valve ( 1 ) of the preceding claim, wherein the recess ( 13 ) in a closed contour around the opening ( 12 ) of the exhaust gas inlet ( 3 ) runs around. The low-pressure EGR valve ( 1 ) one of the two preceding claims, wherein the recess ( 13 ) in a plane to which the central axis ( 10 ) of the exhaust gas inlet ( 3 ) forms a normal. A motor vehicle having an internal combustion engine, an air filter, a compressor, a low-pressure exhaust gas recirculation, and a low-pressure EGR valve connected to the air filter, the low-pressure exhaust gas recirculation, and the compressor ( 1 ) according to one of the preceding claims.

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