EP1359300B1 - Throttle valve unit - Google Patents

Description

The invention relates to a throttle valve unit for use in the exhaust system of an internal combustion engine, comprising a valve body, a shaft rotatably mounted therein about an axis with a closure element, a vacuum unit with a membrane and one of the implementation of the lifting movement of the membrane in a rotational movement of the shaft serving coupling device, wherein a rotational movement of the shaft in the flap position "open" limiting stop means is provided.

Throttle valve units are known in particular from engine construction. Here, the main application area for throttle valves is the regulation of the combustion air or the fuel air mixture. The temperature of the flowing medium is at the level of the ambient air temperature of -20 ° C to + 40 ° C. The structure and operation of the extent known throttle valve units is z. In DE 197 29 648 A1 . DE 40 27 269 A1 . DE 42 09 586 A1 . DE 100 06 795 A1 . DE 199 28 473 A1 . DE 198 57 957 A1 and DE 43 13 454 A1 described.

Within a housing is a planar closure element which is arranged on a housing passing through the rotatable shaft. The shaft is guided in plain bearings. The actuating forces are initiated from the outside. It is used for vacuum or electric drives.

Throttle valve units but also in exhaust systems of internal combustion engines are becoming increasingly important. she Especially in connection with mufflers with variable damping characteristics and the variable design of the mouth noise used (see. E. Santiago u. A., reprint MTZ 53 (1992) Issue 7/8 ; Ch. Lüßgen u. A., System Partners 2000 pp. 54-57 ). Due to the high temperatures in the environment of exhaust systems used here mainly flaps with vacuum box. The externally introduced negative pressure, which depends on the respective operating state of the engine, acts on a membrane, which is connected to a linkage. A lifting movement is generated when vacuum is applied. When no negative pressure is applied, a spring disposed in the vacuum box generates a restoring force; the membrane returns to its original position (cf. DE 197 29 648 A1 and DE 195.26.143 A1 ). The lifting movement of the linkage acts via a crank drive on the shaft and the closure element. The crank mechanism converts the lifting and return movement of the diaphragm and linkage into a rotational movement of the shaft. The vacuum unit is generally arranged by means of a bracket or a mounting bracket on the valve body.

The limitation of the lifting movement of the diaphragm of the vacuum unit takes place during the closing operation in the flap position "closed" by the abutment of the closure element on the inner surface of the valve body. When opening the throttle, the stroke limiter can be specified by a stop acting on the membrane, or it is done by means of a stop for the crank mechanism.

As will be explained in detail below, the high temperatures that throttle units in the Exhaust systems of internal combustion engines are exposed to difficult to control problems.

Functional and manufacturing conditions exist in throttle valve units of the type in question tolerances between plain bearings and shaft on the one hand and the linkage and the crank mechanism on the other. As long as the operating conditions of the throttle valve in a temperature window up to 200 ° C, the fits between shaft and plain bearing, between closure element and valve body and between the crank arm and linkage can be very tight. The lubricants contained in the maintenance-free plain bearings are not consumed over the operating time of the throttle valve. The bearing wear remains relatively low. Once the system has been matched and adjusted during assembly, there is little change in the subsequent operating state.

The temperature of the exhaust gases of internal combustion engines is, however, partly above 850 ° C. The high temperatures lead to the thermal expansion of all components. Associated with this are changes in shape, length and position, changes in distances and spring stresses. A throttle valve assembly, which is mounted with the usual tolerances at an ambient temperature of 20 ° C, changes their switching behavior seriously with such rising temperatures. Frequently, a flap which closes smoothly at ambient temperature will bite and / or close at such high operating temperatures and / or no longer completely close. The conditions of use of flaps in exhaust systems therefore require much greater tolerances between the pairs of bearings than at ambient temperature level.

However, this leads to another problem area. Because with correspondingly increased play between the individual components, the use of such throttle valve units in vehicles, unless special measures are taken against it, due to the inevitable vibrations and vibrations to unacceptable rattling noises.

To avoid such rattling noises was in the DE 43 13 454 A1 proposed to support the throttle shaft by means of spring force against an axial wall of the housing and to use a spring element made of ceramic material. The spring force acts in all valve positions in the axial direction of the shaft. This inevitably leads to increased friction between the shaft and spring on the one hand and throttle and housing on the other hand when operating the throttle shaft. The additional frictional forces must be overcome by additional actuating forces. This requires a larger vacuum box with larger membrane area and a stronger spring to generate the restoring forces.

In DE 197 29 335 It has been proposed that the plain bearings consist of two bearing shells and each bearing half-shell piece has a counter-spring bearing formed by a band spring whose bearing shell portion is under the biasing force of a deformed from the second half of the housing during assembly spring leg. This solution also leads to an increase in the frictional forces and the required actuating forces.

Since conventional lubricants between the moving parts above 550 ° C evaporate or burn, is the rotational movement of the flap also for this reason stiff. The restoring forces would have to be increased for this reason. However, the forces and torques in passenger vehicles available for switching the flaps are very limited in terms of construction space and mass. Furthermore, in the in the DE 197 29 335 A1 and the DE 43 13 454 A1 proposed solutions disadvantageous that these restraints significantly hinder the rotational movement.

With the above-mentioned approaches, the noise problem, namely the rattling of the moving components by vibration excitations in a hot gas application thus can not be resolved. The technical contradiction is the following: Although a slight clearance between moving components reduces the risk of the formation of rattling noises. However, the risk of seizure increases at high operating temperatures. A big game between the moving parts counteracts the seizure, but leads to rattling noises. And spring-loaded friction devices increase the required actuating forces in an unacceptable manner.

In view of the problem set out above, the object underlying the present invention is to provide a throttle valve device of the type specified, which is characterized by a high level of reliability (no jamming!) And low required restoring forces due to minimal noise.

This problem is solved by a throttle valve device with the features of claim 1. Accordingly, the throttle device according to the invention is characterized characterized in that the stop device is designed as an axially acting clamping device comprising a stationary clamping element, a rotatably moved with the shaft clamping element, an axially stationary Hubanschlagelement and with the shaft axially moving Hubanschlagelement, wherein at least one of the two clamping elements inclined to the axis Has control surface on which in the flap position "open" the other clamping element is present, and wherein in the flap position "open" the moving Hubanschlagelement rests against the stationary Hubanschlagelement. In the flap position "open", the two clamping elements in the region of the inclined surface of one of the elements touch each other or lie against each other with two mutually correspondingly inclined surfaces. Due to the inclination of the at least one inclined to the rotation axis control surface is at the end of the opening movement of the throttle, when the two clamping elements abut each other, exerted on the movable, the shaft and the closure element comprehensive unit an axially directed force. This force is absorbed by a - also axially acting - Hubbegrenzungseinrichtung, which includes a stationary Hubanschlagelement and a shaft with the axially moving Hubanschlagelement, which is supported at the flap position "open" on the stationary Hubanschlagelement. In this way, the closure element and the shaft comprehensive unit is clamped with the throttle open, ie fixed in such a way that they can perform within the flap housing no leading to rattling noise movements. There are - as a result of the mechanical vibrations of the exhaust system or the pulsations of the exhaust stream - neither rattling noises between the shaft and bearing, nor between the closure element and the valve body. at the same time In the throttle valve unit according to the invention sufficiently large tolerances between the moving components are possible to compensate for the manufacturing tolerances and deformations due to temperature change and not to hinder the movements even with decreasing lubrication. In addition, only a very small force is required to actuate the flap, which accommodates the limited space available and the limited resources available in vehicles. There are no additional spring elements, which cause an increase in the frictional forces between the sliding bearing and shaft and / or closure element and housing and / or impair the freedom of movement of the moving parts used. In the closed state of the flap, the leakage rate of the exhaust gas is sufficiently small dimensioned and simultaneously ensures "acoustic tightness".

Particularly preferred developments of the throttle valve unit according to the invention are specified in the dependent claims and / or the following description.

According to a first preferred embodiment, the coupling device comprises a link connected to the membrane of the vacuum cell and a link connected to the shaft crank arm, wherein the rotatable clamping element is part of the crank arm. A particular advantage of this development is the comparatively low technical complexity, compared with such an embodiment, in which the clamping device is functionally separated from the coupling device. Also in the sense of a technically simple realization can be provided that the dormant clamping element associated with a mounting bracket is, by means of which the vacuum unit is supported on the valve body.

Particularly preferably, the shaft is mounted in the valve housing by means of two plain bearings. These may be formed from a wire mesh according to a development of the present invention. This is particularly favorable with regard to the sliding properties in the relevant application of the throttle valve unit in the exhaust system of an internal combustion engine. With regard to those plain bearings, another preferred development of the invention is characterized in that at least one of them is designed as a federal government bearing, which is supported in the axial direction outwardly on the valve body. The collar of the federal plain bearing can slightly protrude into the interior of the valve body and forms the stationary Hubanschlagelement. In this case, the moving Hubanschlagelement is particularly preferably formed by a collar or a shoulder of the shaft.

In the context of the present invention, however, numerous other possibilities to execute the two cooperating Hubanschlagelemente conceivable in a corresponding manner. For example, the stationary Hubanschlagelement be formed by the flap housing, on which in the flap position "open" the closure element, which forms the moving Hubanschlagelement in this case, rests under the provided by the clamping force clamping force.

In the flap state "closed" is the closure element, if it is elliptical according to a preferred embodiment, preferably on its outer Scope only in the area of the large radius of the ellipse on the inner shell of the housing. On the side flanks a game is provided. This clearance, which is smaller than the axial extent of the at least one inclined surface of the clamping elements, is used for the (small) axial displacement of the unit comprising the shaft and the closure element during clamping at the end of the opening movement.

Fig. 1

eine Schnittdarstellung der Drosselklappeneinrichtung,

Fig. 2

ein Detail der Klemmeinrichtung in Klappenstellung "offen" in Ansicht schräg von außen,

Fig. 3

ein Detail der Klemmeinrichtung in Ansicht in Klappenstellung "offen" schräg von innen und

Fig. 4

ein Detail der Klemmeinrichtung in Ansicht in Klappenstellung "geschlossen" schräg von innen.

In the following, the present invention will be explained in more detail with reference to an embodiment illustrated in the drawing. It shows

Fig. 1

a sectional view of the throttle device,

Fig. 2

a detail of the clamping device in the flap position "open" in view obliquely from the outside,

Fig. 3

a detail of the clamping device in view in the flap position "open" obliquely from the inside and

Fig. 4

a detail of the clamping device in view in the flap position "closed" obliquely from the inside.

The throttle valve device shown in the drawing for use in the exhaust system of an internal combustion engine has the following basic structure: The valve body 1 and the bearing bushes 2 form the carrier for all other modules. In each bearing bushing 2 designed as a plain bearing plain bearings 3, 4 is used. The plain bearings 3, 4 extend into the interior of the valve housing 1 and are supported in the axial direction to the outside. The plain bearings 3, 4 are made of a wire mesh. The knitted wire has resilient properties.

In the plain bearings 3, 4, the shaft 5, on which a closure element 6, partially surrounding the shaft 5, is arranged, about the axis 7 rotatably mounted (arrow A). Furthermore, the shaft 5 in the slide bearings 3, 4 in the scope described in more detail below also move axially (arrow B). The rotational movements A and the strokes B are, as explained below, limited by corresponding stops.

The collar 8 of the sliding bearing 3 forms a stationary Hubanschlagelement 9. The closure element 6 has with respect to the rotation and stroke limitation a dual function. The part of the closure element 6, which conforms to the shaft 5, forms with its collar 8 of the collar bearing 3 facing portion of the end face 10 a moving Hubanschlagelement 11. The remaining part of the end face 10 seals during the closing operation on the inner shell 12 of the valve body 1 from , Inner casing 12 and closure element 6 limit the rotational movement of the shaft 5 together with the closure element 6 with the flap closed.

At the outer end side of the sliding bearing 3 receiving bushing 2, a mounting bracket 13 is arranged, which carries the vacuum unit 14 with the components contained in the membrane and spring. The linkage 15 transmits the lifting movement of the diaphragm to the crank arm 16. The crank arm 16 converts the lifting movement of the diaphragm into a rotational movement of the shaft 5.

On the mounting bracket 13 with respect to the flap position "open" effective quiescent rotary stop element 17 is arranged. This is designed as a stationary clamping element 18 by one to the axis 7th inclined control surface 19 has. The counterpart as a moving clamping element 20 forms the crank arm 16, which also has a control surface 21 inclined to the axis 7 at its contact surface with the stationary clamping element 18. The stationary and the moving clamping element 18, 20 are arranged radially spaced from the axis of rotation 7 of the shaft 5.

In the flap state "open", the clamping elements 18 and 20 touch each other in the region of their inclined control surfaces 19 and 21. As a result, an axially extending force component is exerted on the shaft 5, which shifts the shaft 5 together with the closure element 6 sideways (arrow B), until the two Hubanschlagelemente 9 and 11 abut each other. As a result, the shaft 5 is clamped together with the closure element 6, so that in the flap position "open" rattling of these parts is prevented in the valve body.

In the flap position "closed", the elliptical closure element 6 lies against its outer periphery 10 only in the area of the large radius of the ellipse on the inner shell 12 of the flap housing. On the side edges opposite the two plain bearings 3, 4 a slight axial clearance is provided. The axial clearance is smaller than the axial extent of the inclined control surfaces 19, 21 of the clamping elements 18, 20th

The throttle device illustrated in the drawing operates as follows: In a corresponding operating condition of the engine, the negative pressure applied to the vacuum unit 14 generates on the diaphragm of the vacuum unit a force exceeding the force of the return spring. The closure element 6 lies in the top described manner on the inner shell 12 of the valve body 1 at. The flap is closed. If the flap is to open, the negative pressure potential is decoupled from the vacuum unit 14. The return spring contained in the vacuum box generates a force in the direction of linkage 15. The linkage rotates the crank arm 16. The shaft 5 begins to rotate.

Arrives shortly before the end of the opening movement of the closure element 6, the moving clamping member 20 on the stationary clamping element 18, then slides with the onset of the first contact of the two clamping elements, the moving clamping element on the inclined control surface 19 of the resting clamping member 18 and additionally generates the rotational movement of the shaft 5 an axial movement. The axial movement is completed when the game between the provided on the closure element moving Hubanschlagelement 11 and provided on the collar 8 of the sliding bearing 3 resting Hubanschlagelement 9 is repealed. It creates a positive connection. The wave can not be moved.

If the flap is to be closed again, the negative pressure in the vacuum box 14 generates a force which is greater than the spring force. The linkage 15 generates a tensile force on the crank arm 16. The above-described non-positive clamping connection is canceled. As the closing movement proceeds, the shutter member 6 starts to contact the casing inner shell 12 on the side adjacent to the crank arm. As the rotational movement progresses, an axial movement and thus a positional orientation for the closure element 6, ie a return of the closure element into its central position, take place again. The original one Achsspiel is restored. The closure element is again in its seal-optimized closure position. Also in this final position, a non-positive connection is made again.

In the open state of the flap, the flow path is released and the exhaust gas flows around the closure element 6. The flowing exhaust gas generated on the closure element 6 is always a force acting in the closing direction when the closure element occupies an intermediate position.

Since frictional connections are generated in both end positions and the flow produces an additional tension in the phases of the transitions between the states "closed" and "open", rattling of a throttle valve designed according to the invention is ruled out. At the same time a sufficient clearance can be specified in order not to hinder both the rotational movement and the position compensation of the closure element.

Claims (11)

1. A throttle valve unit for use in the exhaust system of an internal combustion engine, comprising a valve housing (1), a shaft (5) mounted therein for rotation about an axis (7) and having a closure element (6), a vacuum unit (14) having a diaphragm, and a coupling means that serves to convert the lifting motion of the diaphragm into a rotary motion of the shaft (5), provision being made for a stop means limiting the rotary motion (A) of the shaft (5) in the "open" valve position,
   characterized in that
   the stop means is in the form of an axially active clamping means including a stationary clamping member (18), a clamping member (20) adapted for rotary motion with the shaft (5), an axially stationary travel stop member (9), and a travel stop member (11) axially moving with the shaft (5), at least one of the two clamping members (18, 20) having a control surface (19, 21) which is inclined in relation to the axis (7) and against which the respective other clamping member abuts in the "open" valve position, and the moving travel stop member (11) abutting against the stationary travel stop member (9) in the "open" valve position.
2. The throttle valve unit according to claim 1,
   characterized in that
   the coupling means includes a linkage (15) connected with the diaphragm of the vacuum unit and a crank arm (16) connected with the shaft (5), the rotatable clamping member (20) being part of the crank arm (16).
3. The throttle valve unit according to claim 1 or claim 2,
   characterized in that
   both the stationary (18) and the moving clamping members (20) have a control surface (19, 21) which is inclined in relation to the axis (7).
4. The throttle valve unit according to any of claims 1 to 3,
   characterized in that
   the stationary clamping member (18) is associated with a fastening bracket (13) by means of which the vacuum unit (14) rests against the valve housing (1).
5. The throttle valve unit according to any of claims 1 to 4,
   characterized in that
   the shaft (5) is mounted in the valve housing (1) in two slide bearings (3, 4) at least one of which is in the form of a flanged slide bearing, the flange (8) of the flanged slide bearing forming the stationary travel stop member (9).
6. The throttle valve unit according to claim 5,
   characterized in that
   the moving travel stop member (11) is formed by a flange or a shoulder of the shaft (5).
7. The throttle valve unit according to any of claims 1 to 4,
   characterized in that
   the stationary travel stop member (9) is formed by the valve housing (1).
8. The throttle valve unit according to claim 7,
   characterized in that
   the moving travel stop member (11) is formed by the closure element (6).
9. The throttle valve unit according to any of claims 1 to 8,
   characterized in that
   close to the axis (7) the closure element (6) is shaped to be cylindrical and receives the shaft (5) inside it.
10. The throttle valve unit according to any of claims 1 to 9,
    characterized in that
    the shaft (5) is mounted in the valve housing (1) in two slide bearings (3, 4) which are formed of a wire mesh.
11. The throttle valve unit according to any of claims 1 to 10,
    characterized in that
    in the closed valve position, only the portions of the closure element (6) remote from the axis (7) are in contact with the inner wall (12) of the valve housing (1), whereas adjacent to the axis a small clearance exists between the closure element (6) and the inner wall of the valve housing (1).

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