Device for Controlling an Exhaust Gas Stream

Abstract

The invention relates to a device for controlling an exhaust gas stream, in particular of an internal combustion engine in a passenger vehicle. Said device comprises a housing that can be traversed by exhaust gas (1) and a first displaceable actuating element (5) that is supported on the housing (1). The exhaust gas stream can be selectively guided into a first exhaust gas conduit (3) and/or a second exhaust gas conduit (4) by the displacement of the first actuating element (5). A second actuating element (15) is provided on the housing (1), said actuating element controlling a variable of thee exhaust gas stream.

Description

The present invention relates to a device for controlling an exhaust gas stream according to the preamble of claim 1.

In modern internal combustion engines, especially diesel engines, exhaust gas recirculation systems are increasingly being used to reduce pollutant emissions. These and other systems need devices for regulating and controlling exhaust gas streams, which require independent developments based on the particular requirements such as overall space (especially in passenger motor vehicles), temperature, costs and reliability.

DE 102 03 003 A1 describes an exhaust gas heat exchanger having a housing of rectangular cross section, which encloses a heat exchanger through-flow area and a bypass through-flow area. On the heat exchanger, a control flap mechanically driven by a rotary shaft is provided, by means of which an admission exhaust gas stream can be led either to the heat exchanger area or to the bypass area. A regulating valve downstream of and structurally separated from the heat exchanger is moreover schematically described, which serves for adjusting the aggregate quantity of an exhaust gas stream recirculated to the internal combustion engine.

The object of the invention is to specify a device for controlling an exhaust gas stream, which takes up an exceptionally small overall space and which exhibits a high degree of integration of the components.

According to the invention, in a device of the aforesaid type this object is achieved by the characterizing features of claim 1.

Arrangement of the two actuating elements in one and the same housing permits a considerable reduction in overall space. The housing with the two actuating elements moreover only constitutes one single modular unit, which affords logistical advantages and reduces costs. At the same time, retaining two separate actuating elements, which serve on the one hand for adjusting the aggregate exhaust gas stream and on the other for distributing the exhaust gas stream between two different exhaust gas ducts, makes it possible to retain an especially high degree of flexibility in the adjustment of an exhaust gas ducting, particularly an exhaust gas recirculation for a passenger vehicle diesel engine.

In a preferred embodiment the first of the exhaust gas ducts is connected to an exhaust gas cooler and the second of the exhaust gas ducts to a bypass line for bypassing the exhaust gas cooler. Here, it is particularly preferred if the bypass line is arranged in a common housing together with the exhaust gas cooler. This is a simple way of forming an exhaust gas recirculation system optimally configured for the overall space, making it possible, for example, to operate the bypass line even when the exhaust gas cooler is iced up by exhaust gas condensate, for example.

For a simple mechanical embodiment of the device according to the invention, the actuating element may be driven via a shaft rotatably supported on the housing. The rotatable shaft can furthermore preferably be driven via an actuator supported on the housing, so that the drive unit or the actuator of the first actuating element forms a modular unit together with the device according to the invention.

It is particularly preferred if a valve seat of the second actuating element is provided on the housing. Depending on the requirements with regard to sealing and manufacturing costs, the valve seat may be formed in casting of the housing, followed by any finish-machining required. It may also be a matter, however, of fixedly attaching a separate valve seat to the housing, either by pressing it in or by means of a positively interlocking connection. This is preferably the case when the housing material is not suited to the forming of a valve seat.

It is particularly preferred here if the second actuating element has a valve disk which corresponds to the valve seat and is connected via a valve rod to an actuator. It is particularly preferred if a sub-assembly of the second actuating element, comprising the valve rod and the valve seat, can be detachably connected to the housing. This makes the second actuating element, according to its design type, especially well-suited to proportioning of the exhaust gas stream and at the same time easily accessible for servicing.

In a preferred embodiment, in the area of the first and the second exhaust gas duct the housing has a substantially rectangular cross section enclosing both ducts. Alternatively the cross section may also have a different shape. Exhaust gas coolers with integral bypass duct, as disklosed by the aforementioned DE 102 03 003 A1, for example, which can be connected to the housing in the area of the first and the second exhaust gas duct, are a matter of common knowledge. Such a connection is commonly achieved by permanent welding, but may be a detachable connection, however, where necessary incorporating a means of sealing and in the nature of a bolted flange. Such a detachable connection would make the first actuating element, in particular, easily accessible for servicing.

It is generally preferable to provide a third exhaust gas duct on the housing, which forms a feed or a diskharge for the entire exhaust gas stream of the first and second exhaust gas ducts. A device according to the invention can therefore generally be used so that the actuating elements are assigned to a third exhaust gas duct on the outlet or inlet side. In this case one or the other arrangement of the device may be preferable in an exhaust system, depending on the actual requirements. For an easy and cost-effective connection, the third exhaust gas duct preferably has a substantially circular cross section.

In order to allow an arrangement of the device according to the invention which is tailored to requirements and which is optimally configured for the overall space in an engine compartment of a motor vehicle, in particular a passenger motor vehicle, the third exhaust gas duct, in an adjoining area of the housing, has a different direction to the first and second exhaust gas ducts, the directions of the first and second exhaust gas ducts, in particular, being identical and the direction of the third exhaust gas duct running at an angle of approximately 90° to this.

For a simple arrangement optimally configured for the overall space, starting from the third exhaust gas duct, the second actuating element is first arranged in the housing, followed by the first actuating element and then the first and the second exhaust gas ducts.

An actuator of the first actuating element and/or an actuator of the second actuating element is/are preferably embodied as a pressure capsule. This represents a cost-effective way of providing a drive for the respective actuating element.

An actuator of the first actuating element and/or an actuator of the second actuating element is/are preferably embodied as an electromechanical component. This makes it possible to achieve precise intermediate positions of the actuating elements.

Further advantages and features are set forth in the exemplary embodiment described below and in the dependent claims.

A preferred exemplary embodiment of a device according to the invention will be described below and explained in more detail with reference to the drawings attached, in which:

FIG. 1 shows a three-dimensional overall view of a device according to the invention.

FIG. 2 shows the device in FIG. 1 from a different perspective.

FIG. 3 shows a further three-dimensional view of the device in FIG. 1, a sub-assembly with parts of a second actuating element being represented separately.

FIG. 4 shows a plan view from the side of the device in FIG. 3.

The central element of the device according to the invention is a relatively intricately formed housing 1, which is here manufactured as an integral component by a casting process. However, the housing may also be assembled from multiple individual parts, in particular by welding or also by means of detachable connections.

The housing 1 has an opening 2 of substantially rectangular cross section, which according to FIG. 1 is oriented slanting obliquely to the left out of the plane of projection. This opening 2 forms the end of a first exhaust gas duct 3 and the end of a second exhaust gas duct 4. The two exhaust gas ducts 3, 4 are separated from one another by a first actuating element 5 embodied as a flap. An end baffle plate 5a of the actuating element 5 terminates in the area of the opening 2, where it defines the separation of the two exhaust gas ducts 3, 4. The moving flap 5 is mounted on a rotatable shaft 6, which passes through an outer wall of the housing 1 and is rotatably supported against the housing 1 in the area of this passage. The moving flap 5 bears on seat edges 5b in each of the limit positions of its displacement travel. In each of these limit positions one of the exhaust gas ducts 3, 4 is fully closed and the other fully opened.

Outside the housing 1, the rotary shaft 6 is provided with a return spring 7, an eccentric pivot 8 of the rotary shaft 6 being connected by a push rod 9 to an actuator 10 of the first actuating element 5. The actuator 10 is firmly connected to the housing 1 by a retaining plate 11. The actuator 10 takes the form of a vacuum control unit with a vacuum connection 10a.

As FIGS. 1 and 3 in particular show, a torsion of the rotatable shaft 6 driven by the actuator 10 is capable of producing an adjustment of the control flap 5, such that either the first exhaust gas duct 3 or the second exhaust gas duct 4 is fully or almost fully closed. It is also possible, however, to set an intermediate position, in which an aggregate exhaust gas stream is distributed between the two exhaust gas ducts 3, 4 in a ratio varying as a function of the position of the control flap.

An exhaust gas cooler (not shown) having an integral bypass line has a substantially rectangular cross section and is designed to be connected to the rectangular opening 2 in the housing 1. This connection is, in this case, a permanent connection and is made by welding or brazing. This type of connection will withstand the generally high temperatures in the area of the opening 2. Reference is made, in particular, to the already aforementioned DE 102 03 003 A1 with regards to the design of such an exhaust gas cooler with integral bypass line.

A third exhaust gas duct 12 of the housing 1 terminates in an opening 12a of circular cross section. Via this third exhaust gas duct 12, the housing 1 can be connected via pipes (not shown) to a central exhaust line of an internal combustion engine of a passenger motor vehicle, the connection generally being made to a fixed branch.

After the circular connection opening 12a, the third exhaust gas duct has a 90° bend (see FIG. 2, in particular) and then enters into a widened, substantially cylindrical section 13 of the housing 1. In the area of the section 13 a valve seat 14 of a second actuating element 15 is provided on the housing 1. Here this is a finish-machined area, which is integrally formed with the rest of the housing 1. However, it may also be a pressed-in valve seat made from some other material.

In its wall the cylindrical section 13 has an opening 16, to which the further housing configuration is joined, the cross section of the third exhaust gas duct widening behind the opening 16. In this housing area the exhaust gas stream of the third exhaust gas duct is adjustably distributed to the first exhaust gas duct 3 and the second exhaust gas duct by means of the control flap 5.

At the end of the cylindrical area 13 a flange 17 is provided, to which a sub-assembly of the second actuating element 15 can be tightly bolted. This sub-assembly of the second actuating element 15 comprises a second actuator 18 and a translatory valve rod 19, connected to the actuator 18 and having a valve disk 20, fixed to the end of the valve rod 19, and a mating flange 21. The actuator 18 likewise takes the form of a vacuum control unit having a pressure connection 18a. An electrical connection 18b serves for controlled activation of the actuator 18, a vacuum regulating valve (not shown) being provided in the actuator 18.

When the sub-assembly is tightly connected to the flange 17 via a mating flange 21 connected to the actuator 18, the valve rod 19 with the valve disk projects into the cylindrical section 13 of the housing 1. In this case the valve rod 19, when fully run out from the actuator 18, can press the valve disk 20 tightly into the valve seat 14, so that no more exhaust gas can pass through the cylindrical area 13 and the opening 16. Similarly, a controlled retraction of the valve rod 19 is capable of achieving a defined and proportioned exposure of the opening, so that an aggregate exhaust gas stream of the device according to the invention can be regulated by the second actuating element 15. In the arrangement on a motor vehicle preferred here, the exhaust gas stream impinges on the valve 14, 19, 20 in the opening direction. However, it may also impinge in the closing direction.

As can be seen from the three-dimensional representations according to FIGS. 1 and 2 in particular, in the present embodiment the opening 12a of the third exhaust gas duct 12 is oriented in a direction which runs substantially perpendicular to the direction of the parallel exhaust gas ducts 3, 4. This takes account of an actual, given overall space in a passenger motor vehicle engine compartment. It will be seen that through suitable modification of the connection area of the third exhaust gas duct 12 and a modification of the housing 1, especially in respect of the orientation of the cylindrical area 13 relative to the exhaust gas ducts 3, 4, account can also be taken of some other given overall space.

Claims

1. A device for controlling an exhaust gas stream, especially from an internal combustion engine of a passenger motor vehicle, comprising a housing through which the exhaust gas can flow, and a moveable first actuating element supported on the housing, it being possible, through an adjustment of the first actuating element to lead the exhaust gas stream selectively into a first exhaust gas duct and/or a second exhaust gas duct, wherein a second actuating element for regulating a magnitude of the exhaust gas stream is arranged on the housing.

2. The device as claimed in claim 1, wherein the first of the exhaust gas ducts is connected to an exhaust gas cooler and that the second of the exhaust gas ducts is connected to a bypass line for bypassing the exhaust gas cooler.

3. The device as claimed in claim 2, wherein the bypass line is arranged in a common housing together with the exhaust gas cooler.

4. The device as claimed in claim 1, wherein the first actuating element can be driven by a rotatable shaft supported on the housing.

5. The device as claimed in claim 4, wherein the rotatable shaft can be driven by an actuator preferably supported on the housing.

6. The device as claimed in claim 1, wherein a valve seat of the second actuating element is provided on the housing.

7. The device as claimed in claim 6, wherein the second actuating element comprises a valve disk which corresponds to the valve seat and is connected via a valve rod to an actuator.

8. The device as claimed in claim 7, wherein a sub-assembly of the second actuating element comprising the valve rod and the valve seat can be detachably connected to the housing.

9. The device as claimed in claim 1, wherein in the area of the first and the second exhaust gas ducts the housing has a substantially rectangular cross section enclosing both ducts.

10. The device as claimed in claim 1, wherein a third exhaust gas duct is provided on the housing, which forms a feed or a discharge for the entire exhaust gas stream of the first and second exhaust gas ducts.

11. The device as claimed in claim 10, wherein third exhaust gas duct has a substantially circular cross section.

12. The device as claimed in claim 10, wherein the third exhaust gas duct, in an adjoining area of the housing, has a different direction to the first and second exhaust gas ducts, the directions of the first and second exhaust gas ducts, in particular, being identical and the direction of the third exhaust gas duct running at an angle of approximately 90° to this.

13. The device as claimed in claim 10, wherein starting from the third exhaust gas duct, the second actuating element is first arranged in the housing, followed by the first actuating element and then the first and the second exhaust gas ducts.

14. The device as claimed in claim 1, wherein an actuator of the first actuating element and/or an actuator of the second actuating element is/are embodied as a pressure capsule.