EP1397582A1

EP1397582A1 - Exhaust flap

Info

Publication number: EP1397582A1
Application number: EP02780757A
Authority: EP
Inventors: Martin Unbehaun; Frank Jürgen LEHRINGER; Gerhard Zintel; Gerhard Olejniczak
Original assignee: Faurecia Abgastechnik GmbH
Current assignee: Faurecia Automobiltechnik GmbH
Priority date: 2001-06-19
Filing date: 2002-06-01
Publication date: 2004-03-17
Anticipated expiration: 2022-06-01
Also published as: DE50204096D1; WO2002103173A1; EP1397582B1

Abstract

The invention relates to an exhaust flap (3) for closing an exhaust channel (1). According to said invention, said flap is provided with a closure plate (5) which closes at least part of the cross-section of the exhaust flap (1) whereon the exhaust gas flow is directly guided. A flow body (14), which is arranged close to the closure plate (5) and on which the exhaust flow can be guided, acts as a control element for said exhaust flap (3).

Description

Description exhaust flap

The present invention relates to an exhaust valve for an exhaust system of an internal combustion engine. Exhaust flaps of this type serve to close the exhaust duct of an exhaust system. It may be desirable to close the entire cross section of the exhaust duct with the exhaust flap. However, it is equally possible to close only a partial area of the cross section of the exhaust duct with the exhaust flap. Furthermore, it is also possible to subdivide the exhaust gas duct into a plurality of subchannels and to also connect these subchannels in parallel. The exhaust flap according to the invention is then also suitable for completely or partially closing such a partial duct, while the parallel partial duct can work without an exhaust flap. The exhaust flaps are usually designed in such a way that they can be folded either in different stages or continuously so that the initially closed cross section of the exhaust duct can be opened. In particular, it is possible to flip the exhaust flap back and forth between a closed position in which the exhaust duct is completely closed and an open position in which the exhaust duct is fully open.

The exhaust flaps according to the invention can be used both in the hot and in the cold area of the exhaust system. A typical field of application is the function as a valve, for example for controlling a bypass to bypass a heat exchanger or catalyst. Another typical field of application is the closing of a tailpipe. Finally, it is also common to open and close various flow paths within the silencer in the area of sound attenuation with the aid of exhaust flaps. In this connection, DE-C-199 35 711 discloses a silencer with an exhaust flap, in which an exhaust gas flow acts directly on an actuating element in order to actuate a closure element which forms the actual exhaust gas flap. A disadvantage of this construction is the need to provide both an actuating element and a closure element. These parts are very expensive because the storage of such moving parts is very complex and therefore very expensive because of the tightness and corrosion and heat resistance required here. In the The above-mentioned document also mentions directly controlling flap systems in which the exhaust gas flow acts directly on the exhaust flap. However, it is consistently criticized in the solutions mentioned there that they do not allow stable operating behavior or increase the exhaust gas back pressure too much with high gas throughput.

Starting from this prior art, the invention is based on the object of structurally simplifying an exhaust flap while at the same time ensuring stable operating behavior. This object is achieved by the combination of features of claim 1 in an inventive manner.

The basic idea of the invention is to provide a closing plate that fulfills the closing function on the exhaust flap and to additionally arrange a flow body in addition to the closing plate. The closure plate and flow body are consequently connected to one another and, as parts of the exhaust plate, also pivot synchronously with one another. The flow body can be arranged next to each of the four sides of this rectangle in relation to a rectangular closure plate. The closure plate can be designed so that it completely closes the exhaust duct in the closed position. It is equally possible with the invention to close only a partial area of the cross section of the exhaust duct. Since the sealing plate is arranged directly in the exhaust duct, the exhaust gas flow also strikes the inner surface of the sealing gap facing it. The exhaust gas stream consequently exerts a dynamic pressure on the inner surface of the closure plate. This dynamic pressure is used as an opening force for the closing plate and thus for the exhaust plate. As a result of the dynamic pressure exerted on the closure plate, the exhaust flap can open up to a certain opening angle. Practical tests have shown that, for example on acoustically effective exhaust gas flaps, an opening angle of approximately 30 ° can be achieved with the aid of the dynamic pressure. However, the dynamic pressure exerted on the inside of the closure plate is not sufficient to open the exhaust flap completely, in particular because the opening movement of the exhaust flap is additionally hampered by the force of a return element usually designed as a return spring. As soon as the exhaust flap opens and the flow body is no longer covered, the exhaust gas flow begins to flow towards the flow body arranged next to the closure plate. As a result of this flow against the flow body, the exhaust flap is opened further, so that the flow body acts as an actuator for the exhaust flap. In this way, a stable operating behavior of the exhaust flap is guaranteed. Another advantage of the invention is the fact that in addition to the exhaust flap there are no other moving parts that have to be stored in a complex manner. Rather, the exhaust flap is designed as an integral component which simultaneously fulfills both the actuating function and the closing function of an exhaust flap.

In the back claims, further advantageous and also partially inventive embodiments of the invention are claimed.

According to the teaching of claim 2, it is advantageous to arrange the exhaust flap at the end of a duct section in the exhaust duct. In this way it is possible, for example, to connect several parallel exhaust gas duct sections in series in register form. The arrangement in the region of the end of a duct section has the advantage that the mounting for the exhaust flap can be arranged outside the exhaust duct and thus outside the exhaust gas flow. In this way the

Flow of the exhaust gas flow in the exhaust gas duct is not impeded by the storage. It is also possible to adapt the size of the exhaust duct to the exhaust gas flow and thus optimize the flow behavior in the exhaust duct. Finally, it is advantageous to provide the exhaust flap with a return spring in order to prevent undesirable noise, for example rattling when the flap is closed or when the back pressure is less on the exhaust flap.

Claim 3 teaches a structurally simple and at the same time very effective construction of the exhaust flap. Due to its U-shaped cross-section, the exhaust duct is closed very effectively by the exhaust flap. This structure is consistently developed according to the teaching of claim 4, according to which the side walls of the exhaust flap are extended to form a fork-like receptacle of the flow body between the flap side walls. The inside surfaces of the flap side walls and the inside surface In this construction, the closure plate act like a guide vane of a turbine and thus favor the subsequent flow against the flow body in a particularly advantageous manner.

Claims 5, 6 and 7 relate to alternative configurations of the flow body. It is thus possible to design the flow body as a flat plate in the same way as for the closure plate. The construction is very simple. Alternatively, a curved shape of the flow body can also be considered to improve the flow behavior. The embodiment according to claim 7 is considered to be particularly expedient, according to which the flow body is designed in the manner of an airfoil. Similar to the wing of an aircraft, the end face of the wing is first flown against and the exhaust gas flow is divided into two. Since the exhaust gas flow builds up a higher speed on the upper side of the wing than on the lower side of the wing, the static pressure above the wing is lower than on the underside of the wing, which causes an additional lift of the wing and thus the exhaust flap, which results in the exhaust flap is opened further. In particular in combination with the turbine guide vane-like design of the flap side walls and the closure plate, a complete opening of the exhaust flap can be achieved.

According to claim 8, it is also possible to arrange several flow bodies side by side. For reasons of space, it may make sense to arrange the flow bodies in such a way that they work simultaneously, that is to say are connected in parallel. However, it is equally possible to arrange the flow bodies in such a way that they are only effective one after the other in the manner of a register circuit. Finally, it is also possible to connect several flow bodies in series.

According to claim 9, it is useful to provide the pivot bearing for the exhaust flap at one end, the fixed end and to arrange the flow body at the other end of the exhaust flap, namely at the free end facing away from the fixed end. In this way, the pivot bearing and the flow body are arranged far apart, so that the effective lever arm and thus that on the Exhaust flap torque acting on the flow body is very large, which ensures a quick and safe opening of the exhaust flap.

The invention is further described on the basis of the exemplary embodiments illustrated in the drawings. Show it:

Fig. 1 is a side view of an exhaust duct end with the exhaust flap completely closed

Fig. 2 shows the view of Fig. 1 with the exhaust flap partially open

Fig. 3 shows the view of Fig. 1 with the exhaust flap fully open

4 shows the front view in the exhaust duct according to arrow IV in FIG. 3

Fig. 5 is a bottom view of the exhaust valve

6 is a front view of the exhaust flap according to arrow VI in FIG. 5

7 shows a schematic illustration of the rotary mounting of the exhaust flap on the exhaust duct according to arrow VII in FIG. 4

8 shows a further side view of an exhaust duct end with an embodiment of an exhaust flap with a plurality of flow bodies in the closed position

Fig. 9 schematic diagrams of three functional positions of the exhaust flap as well as the curve of the back pressure curve and the curve of the opening angle plotted against the mass flow.

Exhaust gas duct 1 in FIG. 1 has an exhaust gas flow flowing through it in flow direction 2 and is closed at the end by exhaust gas flap 3. 1 therefore shows the exhaust flap 3 in its closed position. The exhaust flap 3 is U-shaped in cross section (FIG. 6), the flap side walls 4 forming the U legs, which are formed by the U-cross yoke formed by the closure plate 5 are connected to one another. The closure plate 5 and the flap side wall 4 facing the viewer are visible in FIG. 1. The exhaust flap 3 can be seen pivotably mounted about the hinge joint 6. The hinge joint 6 is formed by a hinge pin 7, which hinge pin 7 passes through a bearing eye 8 in the region of the fixed end 9 in each flap side wall 4.

1 also shows a leg, the return spring 10 designed as a leg spring. This leg of the return spring 10 engages in a recess 11 formed in the exhaust flap 3 in the area of the closure plate 5.

In the region of the free end 13 facing away from the fixed end 9 in the transverse direction 12 perpendicular to the flow direction 2, the flow body 14 designed as a wing is attached. The flow body 14 is arranged in the transverse direction 12 next to the closure plate 5. In the exemplary embodiment, the closure plate 5 and the flow body 14 do not overlap in the transverse direction 12. The flow body 14 is also arranged in the region of the lower edge of the flap side walls 4, that is to say in the flow direction 2 on a different plane than the closure plate 5. The flow body 14 is mounted between the flap side walls 4, which for this purpose extends in the transverse direction 12 in a fork-like manner beyond the closure plate 5 are.

2 and 3 show a stop 15 for the exhaust flap 3 facing away from the hinge joint 6 in the transverse direction 12 in the region of the opening of the exhaust duct 1. The stop 15 is designed as a sheet metal flange and carries a type of

Stop cushion effective soft wire mesh 16. The wire mesh 16 prevents rattling noises of the exhaust flap 3 resting on the stop 15 in the closed state. In the illustration in FIG. 4 it can be seen that the stop 15 is designed as an essentially rectangular flange in adaptation to the one shown in FIG 5 recognizable shape of the likewise rectangular-shaped closure plate 5 of the exhaust flap 3. Finally, FIG. 8 shows a further embodiment of the exhaust flap 3. In the area of the free end 13, a flow additional body 17 is provided in addition to the flow body 14. The flow additive body 17 is also in the Embodiment designed as the flow body 14 as a wing. The wings forming the flow body 14 or the flow additional body 17 are usually inexpensive to produce as bent sheet metal parts.

The mode of operation of the exhaust flap 3 according to the invention will be explained with reference to FIGS. 1-3.

In Fig. 1 the closed position of the exhaust valve 3 is shown. Here, the closure plate 5 rests on the flange-shaped stop 15 at the end of the exhaust duct 1. No exhaust gas flow flows through the exhaust duct 1 in FIG. 1.

As soon as an exhaust gas flow flows through the exhaust duct 1 in the flow direction 2, the inside of the closure plate 5 facing the exhaust duct 1 is acted upon by the exhaust gas flow, so that a dynamic pressure builds up on the inside of the closure plate 5. This dynamic pressure exerts a force acting in the flow direction 2 on the closure plate 5 and thus also on the entire exhaust flap 3, so that the exhaust flap 3 is partially opened against the spring pressure of the return spring 10, which is shown in FIG. 2. The exhaust flap 3 lifts to a certain extent driven by the dynamic pressure from the wire mesh 16 at the stop 15 and is swung open about the hinge joint 6.

This open position generated by the dynamic pressure is shown in FIG. 2. In the open state, the exhaust gas flow is conducted on the inside of both the closure plate 5 and the flap side walls 4 in the direction of the free end 13. The inner sides of the closure plate 5 and the flap side walls 4 have the effect of a guide vane of a turbine and bring about a targeted inflow of the flow body 14 as well as along the upper side of the flow body 14 facing the closing plate 5. Since the speed of the air flow on the upper side of the flow body 14 facing the closing plate 5 has a higher speed than on the underside, the Flow body 14 in the manner of an aerofoil of an aircraft, so that the flow generates lift.

As a result of the buoyancy, the exhaust flap 3 is completely opened from its approximately half-open position shown in FIG. 2, as shown in FIG. 3. The exhaust gas flow can flow through the exhaust duct 1 completely unhindered.

The dynamic pressure of the flow impinging on the underside of the closure plate can only generate such a large force that the exhaust flap 3 can move into a half-open position according to FIG. 2 against the spring force of the return spring 10. With the aid of the additional flow body 14 according to the invention, which is attached to the exhaust flap 3, a complete opening of the exhaust flap 3 can be achieved. This is particularly desirable in the full power range because here an exhaust flap 3 protruding into the cross section of the exhaust duct 1 would be an obstacle to flow and would limit the output. It is important in this context that any flap opening position can be realized with the aid of the exhaust gas flow, because in various operating states it may also be desirable not to have the exhaust flap 3 fully opened. With the help of the invention it is thus possible to adjust the exhaust flap 3 continuously between its closed position and its fully open position solely via the exhaust gas flow or to regulate the opening angle of the exhaust flap 3.

The above-described mode of operation of the exhaust flap 3 according to the invention can also be seen in FIG. 9. In the upper half of FIG. 9, the positions of the exhaust flap 3 shown in FIGS. 1, 2 and 3 are shown schematically with some Explanations. The figure at the top left shows, analogously to FIG. 1, the exhaust flap 3 in the closed state. In this closed state, a small flow flows through the exhaust duct 1. This flow is represented by the arrows in the exhaust duct 1.

The table in the lower part of FIG. 9 shows the mass flow measured in kg / h on the abscissa. On the left ordinate, the back pressure acting on the closure plate 5 of the exhaust flap 3 is shown in hPa. The thick dashed line in the graphic shows the course of the back pressure over the mass flow. With the exhaust flap 3 closed, i.e. with a low flow at point A, the mass flow is about 80 kg / h and the counter pressure is about 22 hPa. With a mass flow of 100 kg / h, the counter pressure reaches a maximum at about 35 hPa, the exhaust flap 3 is opened , If the flow continues to grow, ie the mass flow increases, the state of the middle flow shown in the middle representation of the upper half of FIG. 9 is reached. The flow body 14 generates a buoyancy. With a mass flow of 250 kg / h, the back pressure drops from the maximum to about 20 hPa (point B on the thick dashed line). With this mass flow, the opening angle of the exhaust flap 3 is approximately 15 °, which can be seen on the ordinate shown on the right in FIG. 9. The thin dashed line in FIG. 9 shows the opening angle of the exhaust flap 3 in relation to the mass flow.

It is therefore easy to see from the illustration in FIG. 9 that a strong flow, that is to say an increase in the mass flow, leads to the effective counterpressure at the exhaust flap 3 going towards zero, while the exhaust flap opens completely up to 90 °. The functional positions "A: low flow", "B: medium flow" and "C: strong flow" are also identified in the table in FIG. 9 below with A, B and C and in the thick dashed curve of the above The opening angle of the exhaust flap 3 is shown in the table shown below in Fig. 9 in such a way that it always corresponds to the image representation in the basic illustration printed above it. With the low flow shown in basic illustration A the opening angle is 0 ° The exhaust gas flap 3 is closed. In the middle flow shown in schematic representation B, the exhaust gas flap 3 begins to open until it reaches its extreme open position with an opening angle of 90 ° in the strong flow shown in schematic representation C. It should be expressly noted that 9 primarily shows the qualitative course of the mass flow un d of the opening angle shows that the numerical values given relate only to one exemplary embodiment and that other numerical values can result in other embodiments. LIST OF REFERENCE NUMBERS

1st exhaust duct

2. Flow direction

3. Exhaust flap

4. Flap side wall

5. Locking plate

6. Hinge joint

7. Hinge pin

8. Bearing eye

9. Fixed end

10. Return spring

11. Recess

12. Cross direction

13. Freeers

14. Flow body

15th stop

16.Knitted wire

17. Flow additive body

Claims

Expectations

1. Exhaust flap (3) for closing an exhaust gas duct (1) characterized • by a closing plate (5) which is directly flown by the exhaust gas flow and at least partially closes the cross section of the exhaust gas duct (1) and • by an exhaust gas flow arranged next to the closing plate (5) flowable flow body (14) which acts as an actuator for the exhaust flap (3).

2. Exhaust valve according to claim 1, characterized in that the exhaust valve (3) is preferably arranged at the end of a duct section of the exhaust duct (1) and is pivotally mounted against the force of a restoring element, in particular the spring pressure of a restoring spring (10).

3. Exhaust flap according to claim 1 or claim 2, characterized by a U-shaped cross section, the U-legs each form a flap side wall (4) and the U-legs connecting U-

Transverse yoke is the closure plate (5).

4. Exhaust valve according to claim 3, characterized in that the flap side walls (4) are extended like a fork for additional

Holding the flow body (14) between them.

5. Exhaust valve according to one or more of claims 1 to 4, characterized by a flat plate as a flow body (14) with one to the level of

Sealing plate (5) has a flow body plane having an angle of attack.

6. Exhaust valve according to one of claims 1 to 4, characterized by a curved plate designed as a flow body (14) with an angle of attack relative to the plane of the closure plate (5).

7. Exhaust flap according to claim 6, characterized by a flow body designed as a wing (14).

8. Exhaust valve according to one of claims 1 to 7, characterized by a plurality of juxtaposed flow body (14).

9. Exhaust valve according to one of claims 1 to 8, characterized in that the or the flow body (14) at one free end (13) of the exhaust valve (3) are arranged and that a hinge joint (6) and the return spring (10) on the opposite Fixed end (9) are arranged.