DE19733964B4 - Valve arrangement for controlling a recirculated exhaust gas flow - Google Patents

Abstract

Valve arrangement for controlling an externally recirculated exhaust gas flow to an internal combustion engine, wherein the valve assembly comprises two valve seats (12, 13), each associated with a closure member (16) and both closure members (16) on a common actuating mechanism (17) are arranged, which of an actuator (21) is actuated, characterized in that at least one of the closure members (16) is arranged resiliently biased movable on the actuating mechanism (17).

Description

The The invention relates to a valve arrangement for controlling an external recirculated exhaust gas stream on an internal combustion engine according to the preamble of claim 1.

Out WO 96/30635 Several schematic arrangements of an internal combustion engine with an exhaust system and an exhaust gas cooler are known, wherein an exhaust gas recirculation line branches off from the exhaust line, which in turn has a Y-shaped branch. In one branch of this branch, an exhaust gas cooler is used, while the other branch is a bypass for this exhaust gas cooler. Downstream of the exhaust gas cooler, these two branched paths are brought together again in order to introduce appropriately cooled or uncooled, recirculated exhaust gas into an air intake line of the internal combustion engine. This combination has either one or two controlled by an electronic control device, only schematically shown valves.

The US 5,205,265 shows a comparable arrangement with a branch downstream of a catalyst in an exhaust system, wherein first a first valve, the recirculated via this branch exhaust gas flow passes either via an EGR cooler and then via an exhaust filter or a bypass to this EGR cooler.

Furthermore, from the generic German patent DE-621 945 a Leerlaufmengenregler for an internal combustion engine so known that in a mixture feeding line two opposite valve seats are incorporated, on which valve plates rest. These two valve disks are arranged on a common rod. With the throttle closed and therefore in the mixture line prevailing negative pressure of the atmospheric pressure on one of the valve disc acts in the opening direction and opens this against a valve associated with the other spring to ensure the idling fresh air supply. In this arrangement, both valve disks are fixedly arranged on the connecting rod and the opening movement of both valve disks is always carried out together by acting on one of the valve disc pressure difference.

From the generic DE 93 01 419 U1 a valve assembly for exhaust gas recirculation is known, said valve assembly comprises two valve seats, each associated with a closure member, wherein both closure members are arranged on a common actuating mechanism which is actuated by an actuator.

adversely Here it is that this valve device inflexible with respect to the Arrangement of the flow path is over the recirculated exhaust gas is fed.

Of the Invention is based on the object, a generic valve assembly which makes it possible in a structurally simple design, an externally recirculated exhaust gas flow optionally via a flow path or over another flow path respectively.

The solution This object is achieved with the features of claim 1. Advantageous embodiments of the invention are specified in the dependent claims.

According to the invention, it is provided that the valve assembly has two valve seats, each having a closure member, preferably designed as a circular valve disk assigned is, with both closure members on a common operating mechanism are arranged, which in turn is actuated by an actuator. At least one of the closure members is resiliently biased and movable on the actuating mechanism arranged.

advantageously, is through the valve assembly according to the invention a double-seated valve provided by a common Actuator operable either a chilled one or the uncooled, recirculated exhaust gas flow can release. The movable arrangement of one of the closure members, preferably slidable, ensures that when operated in one direction a closure member firmly rests on its valve seat while the other closure member opens while in the other direction of actuation the other closure member firmly rests on his valve seat and opens the first-mentioned closure member.

Preferably are the closure members designed as a circular valve disc on a common actuating rod an actuating mechanism arranged. This actuating rod can the two closure members enforce centrally, to avoid exactly to be observed Tolerances preferred both closure members movable on the actuating rod are arranged.

Farther the actuator is preferably assigned by one of the internal combustion engine electronic control unit dependent on controlled by a plurality of sensor signals, so that a low-emission operation the internal combustion engine is ensured.

In a particularly preferred embodiment is by appropriate control the actuator additionally regulated the recirculated exhaust gas.

For a special simple construction it is preferably provided that within a common housing downstream of two flow paths the valve seats are arranged, downstream of these valve seats a common discharge path is provided.

Further Advantages and features of the invention will become apparent from the dependent claims and the Subsequently explained with reference to a drawing embodiment.

The drawing shows at its lower edge an exhaust pipe 1 an internal combustion engine, not shown, of which a total with 2 designated return line for external return of a portion of the exhaust stream in a recognizable at the top of the image edge, combustion air supplying air line 3 branches.

The return line 2 branches in a fork 4 into an exhaust gas cooler 5 having line section 6 and arranged in a parallel, as a bypass for the exhaust gas cooler 5 acting line section 7 ,

The exhaust gas cooler 5 For example, a cooling coil through which cooling water flows 8th exhibit.

The pipe sections 6 and 7 are sections in a valve assembly according to the invention having housing 9 educated. This has a channel-like flow path 10 for the over the exhaust gas cooler 5 flowing exhaust gas flow and from this ge separates another, channel-like flow path 11 for the over the bypass (line section 7 ) flowing exhaust gas flow.

On the outflow side, both flow paths open 10 and 11 in each case a valve seat 12 and 13 , which as a circular valve plate 14 and 15 trained closure members 16 are mastered.

The two valve plates 14 and 15 are slidable on a part of an operating mechanism 17 forming actuating rod 18 arranged. The operating rod 18 is in a guide bush 19 in the case 9 stored. At this guide bush 19 engages a strongly schematized drawn lever mechanism 20 at which end a double-acting actuator 21 having. This actuator 21 is with the interposition of a converter, not shown by an electronic control unit 25 which in turn is the engine control unit of the internal combustion engine and receives a plurality of sensor signals and controls or regulates other components of the internal combustion engine, not shown.

If no exhaust gas is to be recirculated during operation of the internal combustion engine, for example in the operating-warm state and at a comparatively high load, then the valve arrangement is in the position shown in the drawing, that is to say the return line 2 is by planting the two valve plates 14 and 15 on the seats assigned to them 12 and 13 blocked.

If, for example, exhaust gas is to be recirculated after a cold start of the internal combustion engine in order to reduce emissions, cooling of this exhaust gas is initially undesirable and the actuator 21 moves the operating rod 18 to the left, which makes this one over by means of a federal 26 provided positive engagement on the valve plate 15 attacks and this from his valve seat 13 takes off. This is at the same time one between the two valve plates 14 and 15 coaxial with the operating rod 18 arranged spring 27 compressed, causing the valve disc 14 in addition to his valve seat 12 is pressed. The exhaust gas recirculation rate is in this case over the travel of the actuator 21 adjustable, that is ultimately about the between valve plate 15 and valve seat 13 effective cross-sectional area.

If, for emission reasons, a cooling of the recirculated exhaust gas amount is an advantage, then it is via the control unit 25 the actuator 21 shifted in a further position such that the actuating rod 18 is shifted to the right, creating another fret 28 this operating rod 18 positive fit on the valve plate 14 attacks and this from his valve seat 12 takes off, while at the same time over the compressed spring 27 the valve plate 15 on his valve seat 13 is pressed.

So is cooled or uncooled exhaust gas in the air line 3 returned, this passes either via flow path 10 or flow path 11 in a downstream of the valve plate 14 and 15 arranged Ausströmpfad 29 in the case 9 ,

The actuator 21 can be designed as a double-sided pneumatic box or as an electric servomotor or as a magnetic actuator or for example as a double-acting hydraulic piston or otherwise.

Advantageously, internal housing walls 30 and 31 in the area of the valve seats 12 and 13 designed plan so that they can be provided in a relatively simple manner. Of course, in deviation of the drawing figure is a different type of design of the valve seats 12 and 13 possible, for example, by plane investment of the valve plate 14 and 15 to the housing walls 30 and 31 ,

1

exhaust pipe

2

Return line

3

air line

4

crotch

5

exhaust gas cooler

6

line section

7

line section

8th

cooling coil

9

casing

10

flow path (Li)

11

flow path (re)

12

valve seat (Li)

13

valve seat (re)

14

valve disc (Li)

15

valve disc (re)

16

closure member

17

actuating mechanism

18

actuating rod

19

guide bush

20

lever mechanism

21

actuator

25

control unit

26

Covenant (at 18 re)

27

feather

28

Federation

29

discharge path

30

housing

31

housing

Claims (6)

Valve arrangement for controlling an externally recirculated exhaust gas flow to an internal combustion engine, wherein the valve arrangement comprises two valve seats ( 12 . 13 ), each having a closure member ( 16 ) and both closure members ( 16 ) on a common operating mechanism ( 17 ) are arranged, which of an actuator ( 21 ) is actuated, characterized in that at least one of the closure members ( 16 ) elastically biased movable on the actuating mechanism ( 17 ) is arranged. Arrangement according to claim 1, characterized in that the closure members ( 16 ) as a circular valve disk ( 14 . 15 ) formed on a common operating rod ( 18 ) are arranged. Arrangement according to claim 1 or 2, characterized in that the valve arrangement in a common housing ( 9 ), which has a flow path ( 10 ) for one via an exhaust gas cooler ( 5 ) and a separate flow path ( 11 ) for the exhaust gas cooler ( 5 ) comprises immediate flow of exhaust gas, both flow paths ( 10 . 11 ) downstream of the closure members ( 16 ) and are in a common discharge path ( 29 ). Arrangement according to one or more of the preceding claims, characterized in that the actuator ( 21 ) from an electronic control unit ( 25 ) in response to sensor signals actuated the actuating mechanism ( 17 ) shifts in one of two opposite directions of actuation. Arrangement according to one or more of the preceding claims 2 to 4, characterized in that the actuating mechanism ( 17 ) from the actuator ( 21 ) is movable into at least one exhaust gas recirculation return position, in which both closure members ( 16 ) on their valve seats ( 12 . 13 ), as well as in each case in at least one via the exhaust gas cooler ( 5 ) directed exhaust gas flow recirculating position or the exhaust gas cooler ( 5 ) immediate position. Arrangement according to claim 5, characterized in that the closure members ( 16 ) in any, the recirculated exhaust gas amount regulating positions are movable.