DE102019100402B3 - Valve device for selectively enabling or blocking an exhaust gas recirculation or secondary air flow for an exhaust gas aftertreatment system - Google Patents

Abstract

The invention relates to a valve device (10) for selectively enabling or blocking an exhaust gas recirculation or secondary air flow for an exhaust gas aftertreatment system, comprising a valve housing (12) with an inlet (18) and an outlet (22) for the exhaust gas recirculation or secondary air flow, a valve seat (24), which is arranged between the inlet (18) and the outlet (22) and which forms a valve opening (28), a first closure element (34) which is between a first position in which the first closure element (34) on Valve seat (24) abuts and closes the valve opening (28), and a second position, in which the first closure element (34) opens the valve opening (28), is adjustable, a plunger (16) which can be moved along a longitudinal axis (L) mounted in the valve housing (12) and which is connected to the first closure element (34), an actuating device (30) with which the plunger (16) along the longitudinal axis (L) b It is possible for the first closure element (34) to be adjustable between the first and the second position, a second closure element (36) which, along the longitudinal axis (L), is between a closure position in which the second closure element (36) on the valve seat (24 ) and the valve opening (28) closes, and an open position in which the second closure element (36) opens the valve opening (28), is movable and the plunger (16) is mounted on the plunger (16), the valve device (10 ) has a seal (48) which is fixed in place on the plunger (16) with respect to the plunger (16) and can be moved therewith and which, in the closed position, lies sealingly against the second closure element (36).

Description

The present invention relates to a valve device for selectively enabling or blocking an exhaust gas recirculation or secondary air flow for an exhaust gas aftertreatment system.

When releasing or blocking a secondary air flow, such valve devices serve to re-oxidize unused fuel components in the cold start phase of an internal combustion engine by blowing fresh air into the exhaust gas generated by it. Post-oxidation is a heat-generating, exothermic reaction, with which heat the starting behavior of a catalyst can be improved in order to minimize pollutant emissions. It is therefore necessary to ensure the functionality of the valve device as soon as the internal combustion engine starts.

Valve devices serve, among other things, to release or block an exhaust gas recirculation air flow to reduce the formation of nitrogen oxides as a result of a change in the stoichiometric composition of the fuel / air mixture burned in an internal combustion engine and the combustion temperature prevailing in the process. In this case too, the valve device must be functional during the entire operation of the internal combustion engine.

Such valve devices are for example in the EP 1 369 559 A2 , the DE 94 15 251 Ul, the DE 38 44 453 A2 and the EP 1 860 315 A2 known.

The proposed features and the associated technical effects are discussed below using a secondary air flow provided by a fresh air pump, the technical effects equally applicable to valve devices for releasing or blocking an exhaust gas recirculation air flow.

In the event that the valve device is used to release or block a secondary air flow, the secondary air flow is generated by means of a fresh air pump. In special driving conditions, exhaust gases can flow back to the fresh air pump. However, the exhaust gas and in particular the combustion residues contained in the exhaust gas can damage the fresh air pump, so that such backflows must be avoided.

The main closure element, with which the valve device is opened and closed, is typically attached to such a valve device on a tappet or a rod which is moved axially back and forth by means of an actuating device. In order to avoid the above-mentioned backflows, for example, that in the EP 1 860 315 A2 The valve device shown has a second closure element for this purpose, which is movable between a closed position in which the second closure element rests on the valve seat and closes the valve device, and an open position in which the second closure element releases the valve device and surrounds the tappet on the tappet. The second closure element is not moved via the actuating device, but exclusively via the air flow, so that the second closure element represents a check valve which closes as soon as there is a backflow to the fresh air pump.

In order to ensure the mobility of the second closure element along the plunger, an annular gap is provided between the second closure element and the plunger. In order to prevent exhaust gases from flowing through this gap and reaching the fresh air pump, this gap must be sealed. It has been found, however, that the valve device according to FIG EP 1 860 315 A2 seal used is subject to high wear and tear and therefore often fails. In order to achieve the required reliability, this seal must be manufactured with very high-quality materials, which drive up the costs for the valve device shown there.

The publications form a further state of the art US 6 164 269 A , DE 20 2011 002 351 Ul and CN 104405540 A . An object of an embodiment of the present invention is to provide a valve device with which it is possible to reduce the wear on the seal of the valve device using simple and inexpensive means. At the same time, a compensation of position tolerances should be made possible.

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

• - ein Ventilgehäuse mit einem Einlass und einem Auslass für den Abgasrückführ- oder Sekundärluftstrom,
• - einen Ventilsitz, der zwischen dem Einlass und dem Auslass angeordnet ist und der eine Ventilöffnung bildet,
• - ein erstes Verschlusselement, welches zwischen einer ersten Stellung, in welcher das erste Verschlusselement am Ventilsitz anliegt und die Ventilöffnung verschließt, und einer zweiten Stellung, in welcher das erste Verschlusselement die Ventilöffnung freigibt, verstellbar ist,
• - einen Stößel, der entlang einer Längsachse verschiebbar im Ventilgehäuse gelagert und der mit dem ersten Verschlusselement verbunden ist,
• - eine Betätigungseinrichtung, mit welcher der Stößel derart entlang der Längsachse bewegbar ist, dass das erste Verschlusselement zwischen der ersten und der zweiten Stellung verstellbar ist, und
• - ein zweites Verschlusselement, welches entlang der Längsachse zwischen einer Verschlussstellung, in welcher das zweite Verschlusselement am Ventilsitz anliegt und die Ventilöffnung verschließt, und einer Offenstellung, in welcher das zweite Verschlusselement die Ventilöffnung freigibt, bewegbar und den Stößel umschließend am Stößel gelagert ist, wobei
• - die Ventilvorrichtung eine am Stößel in Bezug auf den Stößel ortsfest befestigte und mit diesem bewegbare Dichtung aufweist, die in der Verschlussstellung dichtend am zweiten Verschlusselement anliegt.

One embodiment of the invention relates to a valve device for selectively enabling or blocking an exhaust gas recirculation or secondary air flow for an exhaust gas aftertreatment system, comprising

• a valve housing with an inlet and an outlet for the exhaust gas recirculation or secondary air flow,
• a valve seat which is arranged between the inlet and the outlet and which forms a valve opening,
• - a first closure element which is adjustable between a first position in which the first closure element lies against the valve seat and closes the valve opening and a second position in which the first closure element releases the valve opening,
• a tappet which is displaceably mounted in the valve housing along a longitudinal axis and which is connected to the first closure element,
• an actuating device with which the plunger can be moved along the longitudinal axis in such a way that the first closure element is adjustable between the first and the second position, and
• - A second closure element, which is movable along the longitudinal axis between a closure position, in which the second closure element rests on the valve seat and closes the valve opening, and an open position, in which the second closure element opens the valve opening, and surrounds the tappet on the tappet, wherein
• - The valve device has a fixed to the plunger with respect to the plunger and movable with this seal, which rests sealingly against the second closure element in the closed position.

A key idea of the proposed valve device is to fix the seal in place with respect to the tappet. In the context of the following description, “stationary with respect to the tappet” should be understood to mean that the tappet and the seal perform the same movements and that there is no relative movement between the tappet and the seal. This is precisely where there is a decisive difference from those from the prior art and in particular from those from EP 1 860 315 A2 known valve devices. The seal with which the gap between the second closure element and the plunger is sealed is the one in the EP 1 860 315 A2 Disclosed valve device fixed to the valve housing, so that with each movement of the plunger, a relative movement between the seal and the plunger takes place. Due to this relative movement, the seal is subject to great wear. In contrast to this, the seal of the proposed valve device is fixed in place on the tappet and only bears against the second closure element in the closed position. The load and wear of the seal of the proposed valve device are compared to the seal in the EP 1 860 315 A2 disclosed valve device significantly reduced, so that the functionality of the seal of the proposed valve device is given significantly longer and yet the seal can be made of a comparatively cheap material.

In the valve arrangement according to the EP 1 860 315 A2 the seal with which the tappet is sealed is attached to the valve seat. So that a valve opening can still be provided, the EP 1 860 315 A2 disclosed a number of webs running towards the tappet and crossing the valve opening. Such webs are not required in the valve arrangement according to the invention, as a result of which the hydraulic cross section can be optimized. The diameter of the valve opening can be reduced with a constant pressure drop and flow and the entire valve opening can be made more compact. The actuating forces for opening and closing the valve opening can be reduced and the actuating device can be dimensioned smaller. The other way around, with constant actuation forces and actuation devices of the same size, larger flow cross-sections of the valve opening and consequently a more favorable flow (lower pressure drop, increased flow) can be realized.

In accordance with another embodiment, the seal has a sealing contour and the second closure element has a counter-sealing contour corresponding to the sealing contour, which abut one another in the closed position. A sealing contour and a counter-sealing contour are to be understood in the following as three-dimensional structures, so that the seal and the second closure element can not only abut one another on a flat sealing surface, but also on a curved and / or inclined sealing surface. The sealing contour and the counter-sealing contour can be designed in such a way that a particularly large sealing surface is created. The seal is then particularly effective.

In a further developed embodiment, the sealing contour can be designed in such a way that it is softer than the counter-sealing contour, with the counter-sealing contour enclosing the sealing contour at least in sections in the closed position. In this context, the term “soft” denotes in particular the deformability of the sealing contour and the counter-sealing contour. The deformability can be adjusted via the geometry of the sealing contour and the counter-sealing contour as well as via the materials used. For this purpose, for example, the wall thickness can be chosen to be correspondingly thinner or thicker, and particularly easily deformable or particularly rigid sections can be provided. When the counter-sealing contour engages in the sealing contour, the sealing contour can deform accordingly due to the softer design, so that the Sealing diameter and / or sealing angle between the sealing contour and the counter-sealing contour can be changed and a tolerance compensation can also be created in the event of wear. As a result, the sealing effect can be maintained longer. This effect can also be achieved if the second closure element is designed softer than the seal and the sealing contour encloses the counter-sealing contour. However, it makes sense to make the entire second closure element harder in order to give the second closure element the necessary mechanical stability.

In a further developed embodiment, the seal can have a projection, so that an annular space is formed between the tappet and the seal, the sealing contour being arranged on the projection. According to the proposal, the sealing contour is part of the seal, which is fixed in place on the tappet, while the counter-sealing contour is part of the second closure element. In the case of a backflow, the exhaust gas can flow through the gap between the second closure element and the tappet and penetrates into the annular space. As a result, the exhaust gas presses the softer material of the sealing contour radially outward against the counter-sealing contour, so that the back-flowing exhaust gas increases the surface pressure between the sealing contour and the counter-sealing contour and consequently the sealing effect.

• - ein erster Dichtabschnitt angeordnet ist, an welchem das erste Verschlusselement in der ersten Stellung anliegt, und/oder
• - ein zweiter Dichtabschnitt angeordnet ist, an welchem das zweite Verschlusselement in der Verschlussstellung anliegt.

A further developed embodiment is characterized in that the valve seat and the valve opening are formed by a disk-shaped body on which

• - A first sealing section is arranged, on which the first closure element rests in the first position, and / or
• - A second sealing section is arranged, on which the second closure element bears in the closed position.

In this embodiment, the first closure element and the second closure element come to rest on different sealing sections. It is therefore possible to optimize the design of the first sealing section and the second sealing section for the properties of the first closing element and the second closing element, respectively, in order to increase the sealing effect of the entire valve device and to maintain it over a long operating period.

According to a further embodiment, the sealing contour and the counter-sealing contour are designed such that they already abut one another when the second sealing section comes into contact with the second closure element. This allows axial component tolerances to be compensated for.

A further developed embodiment is characterized in that the valve device comprises a biasing element for biasing the second closure element into the closed position. The biasing element is designed such that when the fresh air pump provides a secondary air flow, it allows the second closure element to be opened, but when a backflow occurs, it ensures that the second closure element is moved into the closed position. The pretensioning element can be set in such a way that the second closure element is already placed in the closed position when there is only a very small secondary air flow and therefore a backflow is imminent. Damage to the fresh air pump by the exhaust gas is thus prevented with a high probability.

According to another embodiment, the prestressing element is designed as a spring enclosing the plunger. Springs are available in a variety of designs so that they can be selected without great effort according to the requirements to be met. The plunger can also be used as a guide for the spring to prevent the spring from buckling.

Another embodiment is characterized in that the spring is arranged between the first closure element and the second closure element. The arrangement of the spring according to this embodiment is distinguished by the fact that no significant design changes have to be made to the first closure element and to the second closure element.

• 1 eine perspektivische Ansicht einer Ausführungsform der erfindungsgemäßen Ventilvorrichtung,
• 2 eine Draufsicht auf die in 1 dargestellte Ausführungsform der erfindungsgemäßen Ventilvorrichtung,
• 3 eine Schnittdarstellung durch die in den 1 und 2 gezeigte Ausführungsform der erfindungsgemäßen Ventilvorrichtung in einem ersten Betriebszustand entlang der in 2 definierten Schnittebene A-A,
• 4 eine vergrößerte Darstellung des der in 3 gekennzeichneten Ausschnitts X,
• 5 eine Schnittdarstellung durch die in den 1 und 2 gezeigte Ausführungsform der erfindungsgemäßen Ventilvorrichtung in einem zweiten Betriebszustand entlang der in 2 definierten Schnittebene A-A, und
• 6 eine vergrößerte Darstellung des der in 5 gekennzeichneten Ausschnitts Y.

An exemplary embodiment of the invention is explained in more detail below with reference to the accompanying drawings. Show it

• 1 2 shows a perspective view of an embodiment of the valve device according to the invention,
• 2nd a top view of the in 1 illustrated embodiment of the valve device according to the invention,
• 3rd a sectional view through the in the 1 and 2nd Shown embodiment of the valve device according to the invention in a first operating state along the in 2nd defined cutting plane AA ,
• 4th an enlarged view of the in 3rd featured clipping X ,
• 5 a sectional view through the in the 1 and 2nd Shown embodiment of the valve device according to the invention in one second operating state along the in 2nd defined cutting plane AA , and
• 6 an enlarged view of the in 5 marked section Y.

In the 1 and 2nd is an embodiment of a valve device according to the invention 10th with which, for example, a secondary air flow can be provided for an exhaust gas aftertreatment system, not shown here. The valve device 10th has a valve housing 12 on which a neck 14 is attached, which in turn can be connected to a hose, not shown, which can be connected to a fresh air pump, also not shown. The fresh air pump provides the secondary air flow, that of the fresh air pump via the hose and the nozzle 14 in the valve housing 12 is initiated. A return flow is also discussed below, by which an exhaust gas flow to the fresh air pump is to be understood, which flows in a direction opposite to the secondary air flow. Such a backflow is intended with the proposed valve device 10th be prevented since the exhaust gases contained in the backflow could damage the fresh air pump.

Especially from the 1 it can be seen that in the valve housing 12 a pestle 16 which is stored along its longitudinal axis L (cf. in particular 3rd to 6 ) relative to the valve housing 12 is movable.

In 3rd is in the in the 1 and 2nd valve device shown 10th based on a sectional view along the in 2nd defined cutting plane AA shown, the valve device 10th is in a first operating state. It can be seen that the valve housing 12 an inlet 18th has, via which the aforementioned secondary air flow through the nozzle 14 in the valve housing 12 can be initiated. From the 3rd is clearly recognizable that the nozzle 14 fluidly with the inlet 18th is connected and a connecting portion 20th on which the hose on the nozzle 14 can be attached. Furthermore, the valve housing 12 an outlet not shown here 22 on which the secondary airflow flows through the valve housing 12 can leave again. The outlet 22 is connected to the exhaust gas aftertreatment system via a pipe system, also not shown here.

The valve device 10th has a valve seat 24th on, in the illustrated embodiment of a disc-shaped body 26 is formed, which is fixed to the valve housing 12 connected and opposite the valve housing 12 is sealed. The disc-shaped body 26 forms a valve opening 28 which from the already mentioned pestle 16 is penetrated. Around the pestle 16 along its longitudinal axis L Moving back and forth is an actuator 30th provided, which is shown only schematically here. Furthermore is off 3rd recognizable that the pestle 16 outside the valve housing 12 with a return spring 32 interacts, which is oriented so that the pestle 16 in the event that the actuator 30th should fail in the in 3rd position shown is reset.

The pestle 16 is with its the actuator 30th opposite end with a first closure element 34 connected, which with the plunger 16 between a first position in which the first closure element 34 at the valve seat 24th is applied and the valve opening 28 closes, and a second position is adjustable, in which the first closure element 34 the valve opening 28 releases and therefore no longer at the valve seat 24th is present. The first position is in the 3rd and 4th shown during the second position of the first closure element 34 in the 5 and 6 is shown.

It also includes the valve device 10th a second closure element 36 which along the longitudinal axis L of the pestle 16 between a closed position in which the second closure element 36 at the valve seat 24th is applied and the valve opening 28 closes, and an open position in which the second closure element 36 the valve opening 28 releases and therefore no longer at the valve seat 24th is present, is movable. The movability of the second closure element 36 in relation to the plunger 16 ensure between the plunger 16 and the second closure element 36 there is an annular gap, not visible in the figures. In the 3rd to 6 is the second closure element 36 in the closed position.

The following will focus in particular on the 4th referenced which the in 3rd marked neckline X reproduces enlarged. The first closure element 34 is essentially U-shaped and encloses a cavity 38 in which the second closure element 36 is introduced in the first operating state. In the cavity 38 is a preload element 40 arranged, which in the example shown as a spring 42 is trained. The feather 42 is between the first closure element 34 and the second closure element 36 arranged and tensioned the second closure element 36 in the closed position.

The disk-shaped body already mentioned 26 has a first sealing section 44 and a radially inside the first sealing section 44 arranged second sealing section 46 on. In the first Position is the first closure element 34 sealing on the first sealing section 44 while the second closure element 36 sealing in the closed position on the second sealing section 46 is present.

In addition, the valve device 10th one on the pestle 16 in relation to the plunger 16 fixed and movable with this seal 48 on. The plunger points to this 16 an annular recess 49 on which the seal 48 is positively introduced. The seal 48 forms one approximately parallel to the longitudinal axis L of the pestle 16 trending lead 50 , on its radially outward-facing surface an approximately conical sealing contour 52 is trained. By having the lead 50 roughly parallel to the longitudinal axis L of the pestle 16 and extends radially spaced therefrom, encloses the seal 48 an annular space 54 which is consequently between the pestle 16 and the seal 48 is arranged.

The second closure element 36 points to the sealing contour 52 corresponding counter seal contour 56 on, which is also approximately conical. With the geometry of the seal 48 and with the material used, the seal can 48 be equipped with a certain deformability. The sealing angle between the sealing contour 52 and the counter seal contour 56 can be adjusted with the deformability and tolerance compensation can be realized.

The valve device 10th is operated in the following way: As already mentioned, the valve device is located 10th in 3rd and 4th in a first operating state in which the first closure element 34 in the first position and the second closure element 36 are in the closed position. As a result, the valve opening 28 both from the first closure element 34 as well as the second closure element 36 locked. A secondary air flow provided by the fresh air pump can therefore open the valve 28 do not flow through and do not reach the exhaust gas aftertreatment system.

However, if a secondary air flow is to be applied to the exhaust gas aftertreatment system, the actuating device is used 30th which activates the pestle 16 regarding the in the 3rd to 6 selected representations moved downward, so that the first closure element 34 is placed in the second position (cf. 5 and 6 ). Activation of the actuator 30th however, does not cause the second closure element 36 is placed in the open position. The second closure element 36 is only adjusted by the flow that is set up, so that when the fresh air pump provides a secondary air flow, the second closure element 36 is moved down to the open position. Now the secondary airflow can open the valve 28 flow through so that the exhaust gas treatment system can be supplied with secondary air. This operating state is not shown in the figures.

In the event that a backflow to the fresh air pump should occur, the second closure element 36 put back in its closed position, as in the 5 and 6 shown second operating state is the case. The sealing contour takes effect 52 in the counter seal contour 56 and seals the annular space 54 from. The annular gap between the plunger 16 and the second closure element can still flow through the exhaust gas, which then in the annular space 54 can reach. But there is the ring-shaped space 54 from the seal 48 is sealed, the exhaust gas can no longer flow towards the fresh air pump. Because the valve opening 28 due to the installation of the second closure element 36 at the second sealing section 46 is closed, there is a backflow through the valve opening 28 prevented.

In the second operating state, the valve opening 28 from the second closure element 36 , but not from the first closure element 34 locked. The first closure element 34 remains in its second position. This operating state is in the 5 and 6 shown.

From these explanations it is clear that the first closure element 34 by means of the actuating device 30th is moved between the first position and the second position while the second closure element 36 is moved by the flow between the closed position and the open position. The movement of the second closure element 36 from the open position to the closed position is by the spring 42 supports to make sure that even with a low backflow the valve opening 28 from the second closure element 36 is closed. The fresh air pump is therefore protected against damage caused by the exhaust gas.

Reference symbol list

10th

Valve device

12

Valve body

14

Support

16

Pestle

18th

inlet

20th

Connecting section

22

Outlet

24th

Valve seat

26

disc-shaped body

28

Valve opening

30th

Direction of actuation

32

Return spring

34

first closure element

36

second closure element

38

cavity

40

Preloading element

42

feather

44

first sealing section

46

second sealing section

48

poetry

50

head Start

52

Sealing contour

54

annular space

56

Counter seal contour

L

Longitudinal axis

Claims (9)

Valve device (10) for selectively enabling or blocking an exhaust gas recirculation or secondary air flow for an exhaust gas aftertreatment system, comprising - a valve housing (12) with an inlet (18) and an outlet (22) for the exhaust gas recirculation or secondary air flow, a valve seat (24) which is arranged between the inlet (18) and the outlet (22) and which forms a valve opening (28), - A first closure element (34) which closes between a first position in which the first closure element (34) rests on the valve seat (24) and the valve opening (28), and a second position in which the first closure element (34) Valve opening (28) releases, is adjustable, a tappet (16) which is mounted in the valve housing (12) and can be moved along a longitudinal axis (L) and which is connected to the first closure element (34), an actuating device (30) with which the plunger (16) can be moved along the longitudinal axis (L) in such a way that the first closure element (34) can be adjusted between the first and the second position, - A second closure element (36) which, along the longitudinal axis (L), between a closure position in which the second closure element (36) rests on the valve seat (24) and closes the valve opening (28), and an open position in which the second closure element (36) releases the valve opening (28), is movable and surrounds the tappet (16) on the tappet (16), wherein - The valve device (10) has a fixed on the plunger (16) in relation to the plunger (16) and movable with this seal (48), which rests in the closed position sealingly against the second closure element (36). Valve device (10) after Claim 1 , characterized in that the seal (48) has a sealing contour (52) and the second closure element (36) has a counter-sealing contour (56) corresponding to the sealing contour (52), which abut one another in the closed position. Valve device (10) after Claim 2 , characterized in that - the sealing contour (52) is designed such that it is softer than the counter-sealing contour (56) and - in the closed position the counter-sealing contour (56) encloses the sealing contour (52) at least in sections. Valve device (10) after Claim 3 , characterized in that the seal (48) has a projection (50) so that an annular space (54) is formed between the tappet (16) and the seal (48), the sealing contour (52) on the projection ( 50) is arranged. Valve device (10) according to one of the preceding claims, characterized in that the valve seat (24) and the valve opening (28) are formed by a disc-shaped body (26) on which - a first sealing section (44) is arranged, on which the first closure element (34) bears in the first position, and / or - a second sealing section (46) is arranged, on which the second closure element (36) bears in the closed position. Valve arrangement according to the Claims 2 and 5 , characterized in that the sealing contour (52) and the counter-sealing contour (56) are designed such that they already abut one another when the second sealing section (46) comes into contact with the second closure element (36). Valve device (10) according to one of the preceding claims, characterized in that the valve device (10) comprises a biasing element (40) for biasing the second closure element (36) into the closed position. Valve device (10) after Claim 7 , characterized in that the biasing element (40) is designed as a spring (42) surrounding the plunger (16). Valve device (10) after Claim 8 , characterized in that the spring (42) is arranged between the first closure element (34) and the second closure element (36).

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