EP1359300A2 - Throttle valve unit - Google Patents

Abstract

The throttle flap for a motor vehicle internal combustion engine exhaust duct has a housing (1) with a pivot shaft (5) on which is mounted the throttle flap (6). The shaft is connected to a vacuum chamber (14) with a diaphragm. The flap has an axially operating stop to define its open position, with a fixed stop (18) on a mounting plate engaging a stop (20) mounted on the flap shaft. The shaft also has an axially fixed stop ring (9) and an axially movable stop (11).

Description

The invention relates to a throttle valve unit for use in the exhaust system of an internal combustion engine, comprising a valve body, one therein shaft rotatable about an axis with a closure element, a vacuum box with a membrane as well as implementing the lifting movement of the membrane in a coupling device serving to rotate the shaft, one being the rotational movement of the shaft in the flap position "open" limiting anchorage device provided is.

Throttle valve units are particularly well known from engine construction. Here is the main area of application regulation of throttle valves Combustion air or the fuel air mixture. The The temperature of the flowing medium is on the Ambient air temperature level from -20 ° C to + 40 ° C. The structure and operation of the known so far Throttle valve units is e.g. B. 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.

There is a flat closure element within a housing, that on a penetrating the housing rotatable shaft is arranged. The wave is in Slide bearings performed. The actuating forces are from the outside initiated. Vacuum cans or are used for this electric motors.

Throttle valve units are becoming increasingly important but also in exhaust systems of internal combustion engines. she come in particular in connection with silencers with variable damping characteristics or the variable Design of the muzzle noise for use (see E. Santiago et al., special print MTZ 53 (1992) issue 7/8; Ch. Lüßgen u. A., System Partners 2000 p. 54 - 57). Because of the high temperatures around exhaust systems mainly flaps are used here Vacuum unit. The negative pressure introduced from the outside, which depends on the particular operating state of the engine, acts on a membrane with a linkage connected is. A stroke is generated when Negative pressure is present. If no vacuum is present a spring arranged in the vacuum box Restoring force; the membrane returns to its starting position back (see DE 197 29 648 A1). The lifting movement of the Linkage acts on the shaft via a crank mechanism and the closure element. The crank mechanism sets the Stroke and return movement of membrane and linkage in a rotational movement of the shaft. The vacuum can i.a. by means of a bracket or a mounting bracket arranged on the valve body.

Limiting the stroke movement of the membrane of the vacuum box takes place in the flap position during the closing process "closed" by striking the Closure element on the inner surface of the valve body. When opening the throttle valve, the Stroke limitation through an acting on the membrane Stop can be specified, or it takes place by means of a stop for the crank mechanism.

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

Functional and production-related exist with throttle valve units tolerances of the type in question here between plain bearing and shaft on the one hand and the linkage and the crank mechanism on the other. So long the operating conditions of the throttle valve in a temperature window fits can be up to 200 ° C between the shaft and slide bearing, between the closure element and flap housing and between the crank arm and Be very narrow. The in the maintenance-free Lubricants contained in plain bearings not used up over the operating time of the throttle valve. Bearing wear remains relatively low. is the system is coordinated once during assembly and adjusts, changes in the following Operating condition little.

The temperature of the exhaust gases from internal combustion engines is meanwhile partly above 850 ° C. The high temperatures lead to thermal expansion of all components. In order to changes in shape, length and position are connected, change of the distances and spring tensions. A throttle valve unit, with the usual tolerances an ambient temperature of 20 ° C is changed their switching behavior seriously with such rising temperatures. One often bites and sticks flap that closes easily at ambient temperature at such high operating temperatures and / or no longer closes completely. The conditions of use of flaps in exhaust systems therefore require substantial greater tolerances between the sliding pairings than on Ambient temperature level.

However, this leads to another problem area. Because with a correspondingly increased game between the the use of such throttle valve units leads to individual components in vehicles if not special Measures against this are taken as a result of the inevitable Shocks and vibrations too acceptable rattling noises.

To avoid such rattling noises was in the DE 43 13 454 A1 proposed the throttle valve shaft by means of spring force against an axial wall of the housing support and a spring element made of ceramic material to use. The spring force works in all of them Flap positions in the axial direction on the shaft. The leads inevitably when the throttle valve shaft is actuated to increased friction between the shaft and spring on the one hand and throttle valve and housing on the other. The additional frictional forces have to be added Actuators are overcome. That requires a bigger one Vacuum can with a larger membrane area and one stronger spring to generate the restoring forces.

In DE 197 29 335 it was proposed that the plain bearing consist of two bearing shells and each bearing half-shell piece one formed by a band spring Counter-half bearing, the bearing shell section under the biasing force of one of the second half of the housing there is deformed spring leg during assembly. This solution also leads to an increase in Frictional forces and the necessary actuating forces.

As usual lubricant between the moving Vaporize or burn parts above 550 ° C the rotary movement of the flap for this reason too stiff. The actuators would also need this Reason to be enlarged. The one for switching the flaps available forces and torques in passenger vehicles however, are space and mass related very limited. Furthermore, in DE 197 29 335 A1 and DE 43 13 454 A1 proposed solutions disadvantageous that this clamping the rotational movement significantly hinder.

With the solutions listed above, the noise problem is namely the rattling of the moving components through vibration excitation at a Hot gas application cannot therefore be remedied. The technical The contradiction is as follows: a minor game between moving components reduces the risk the creation of rattling noises. However, the Risk of seizing at high operating temperatures. A big game between the moving parts works that Seize against, but leads to rattling noises. And spring-loaded friction devices increase that required actuators in an unacceptable manner.

In view of the problems outlined above is the basis of the present invention Task in it, a throttle valve device to provide the type specified at the outset with high operational safety (no jamming!) and low actuating forces required by a minimal Distinctive noise development.

This task is solved by a throttle valve device with the features of claim 1. Accordingly, the throttle valve device according to the invention is distinguished characterized in that the anchor device designed as an axially acting clamping device which is a resting clamping element, one with the shaft rotatable clamping element, an axially stationary stroke stop element and one axially moved with the shaft Stroke element comprises, at least one of the two clamping elements a control surface inclined to the axis has on the "open" in the flap position each other clamping element is applied, and wherein in the Flap position "open" the moving stroke stop element rests on the stationary stroke stop element. In the Flap position "open" touch the two clamping elements in the area of the inclined surface one of the Elements or lie with two corresponding to each other inclined surfaces. Because of the inclination the at least one control surface inclined to the axis of rotation at the end of the opening movement of the throttle valve, if the two clamping elements lie against each other, on the movable, the shaft and the closure element comprehensive unit exerted an axially directed force. This force is absorbed by one - also axially acting - stroke limiting device, which a stationary stroke stop element and one with the shaft axially moving stroke stop element, which is in the flap position "open" on the stationary stroke stop element supports, includes. In this way, the closure element and the unit encompassing the shaft when open Throttle valve clamped, i.e. such fixed that they were not inside the valve body Can make rattling noises leading movements. It arises - as a result of mechanical vibrations the exhaust system or the pulsations of the exhaust gas flow - neither rattling noises between shaft and bearing, nor between the closure element and the valve body. at the same time are in the throttle valve unit according to the invention sufficiently large tolerances between the moving components possible to the manufacturing tolerances and deformations compensate due to temperature change and the movements do not work even if the lubrication is reduced to hinder. To operate the flap is also only a very small force is required, which is the tight Available space and the available limited Equipment in vehicles. There are no additional spring elements, one Increasing the frictional forces between the plain bearing and the shaft and / or cause closure element and housing and / or the freedom of movement of the moving parts impair, used. When closed the flap is the leak rate of the exhaust gas sufficiently small and at the same time "acoustic Tightness "guaranteed.

Particularly preferred developments of the invention Throttle valve unit are in the subclaims specified and / or the following description removable.

According to a first preferred development, the Coupling device with the membrane of the vacuum box connected linkage and one connected to the shaft Crank arm, the rotatable clamping element part of the crank arm. A particular advantage of this training is the comparatively low technical effort, compared to such an embodiment in which the clamping device is functionally separate from the Coupling device. Also in the sense of a technical simple implementation can be provided that the resting clamping element is assigned to a mounting bracket is, by means of which the vacuum can supports the valve body.

The shaft in the flap housing is particularly preferred stored by means of two plain bearings. According to a development of the present invention from a Wire mesh should be formed. This is special favorable with regard to the sliding properties of the relevant application of the throttle valve unit in the exhaust system of an internal combustion engine. With regard another one stands out on those plain bearings preferred development of the invention characterized in that at least one of them designed as a plain sliding bearing is in the axial direction on the outside of the valve body supported. The collar of the collar sliding bearing can protrude slightly into the interior of the valve body and forms the stationary stroke stop element. In this Trap is the moving stroke stop element special preferably by a collar or a shoulder of the shaft educated.

However, within the scope of the present invention accordingly numerous other ways to execute the two interacting stroke stop elements, conceivable. For example, the stationary stroke stop element be formed by the valve body, on which in the flap position "open" the closure element, which in this case is the moving stroke stop element forms, under that of the Clamping device provided clamping force is present.

In the flap state "closed", the closure element lies, if it is according to a preferred further education is elliptical, preferably on its outer Extent only in the area of the large radius of the ellipse on the inner casing of the housing. On the side flanks a game is planned. This game that 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 shaft and the closure element comprehensive unit when clamping at the end of the opening movement used.

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.

The present invention is explained in more detail below on the basis of an exemplary embodiment illustrated in the drawing. It shows

Fig. 1

2 shows a sectional illustration of the throttle valve device,

Fig. 2

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

Fig. 3

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

Fig. 4

a detail of the clamping device 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 assemblies. In each Bearing bushing 2 is designed as a plain sliding bearing Plain bearings 3, 4 used. The plain bearings 3, 4 are sufficient inside the flap housing 1 and support outwards in the axial direction. The plain bearings 3, 4 are made from a wire mesh. The wire mesh has elastic properties.

In the plain bearings 3, 4 is the shaft 5 on which a Closure element 6, partially enclosing shaft 5, is arranged to be rotatable about the axis 7 (arrow A). Furthermore, the shaft 5 can be in the plain bearings 3, 4 to the extent described in more detail below move axially (arrow B). The rotary movements A and the lifting movements B are, as explained below, limited by appropriate stops.

The collar 8 of the plain bearing 3 forms a stationary stroke stop element 9. The closure element 6 has in relation on the rotation and stroke limitation Dual function. The part of the closure element 6, the nestles on the shaft 5, forms with his Bund 8 of the federal camp 3 facing section of the End face 10 a moving stroke stop element 11. The remaining part of the end face 10 seals during the closing process on the inner casing 12 of the valve housing 1. Inner jacket 12 and closure element 6 limit the Rotational movement of the shaft 5 together with the closure element 6 with the flap closed.

On the outer end face of the slide bearing 3 receiving Bearing bush 2, a mounting bracket 13 is arranged, the vacuum box 14 with the inside contained diaphragm and spring components. The linkage 15 transmits the lifting movement of the membrane to the Crank arm 16. The crank arm 16 converts the lifting movement the diaphragm into a rotary movement of the shaft 5.

On the bracket 13 is a with regard to Flap position "open" effective rotating stop element 17 arranged. This is as a resting clamping element 18 carried out by an axis 7 inclined control surface 19. The counterpart as moving clamping element 20 forms the crank arm 16, the on its contact surface with the resting clamping element 18 also a control surface inclined to the axis 7 21 has. The resting and the moving Clamping element 18, 20 are radial from the axis of rotation 7 of the Shaft 5 spaced.

When the valve is in the "open" state, the clamping elements touch 18 and 20 in the area of their inclined control surfaces 19 and 21. As a result, the shaft 5 is an axial Directed force component exerted, which the shaft 5 together with the closure element 6 sideways (Arrow B) moves until the two stroke stop elements 9 and 11 lie against each other. This will make the Shaft 5 together with the closure element 6, so that in the flap position "open" rattling this Parts in the valve body is prevented.

In the flap position "closed" is the elliptical Closure element 6 on its outer circumference 10 only in the area of the large radius of the ellipse on the inner jacket 12 of the valve body. On the side flanks is a small compared to the two plain bearings 3, 4 axial play provided. The axial play is there smaller than the axial extent of the inclined control surfaces 19, 21 of the clamping elements 18, 20.

The throttle device illustrated in the drawing works as follows: With a corresponding The operating state of the engine is generated by the vacuum box 14 negative pressure applied to the membrane of Vacuum can exceeds the force of the return spring Force. The closure element 6 lies in the top described manner on the inner casing 12 of the valve housing 1 on. The hatch is closed. Shut up open, the vacuum potential from the vacuum box 14 decoupled. The one contained in the vacuum box Return spring generates a force in the direction Linkage 15. The linkage turns the crank arm 16. The Wave 5 starts to spin.

Strikes just before the end of the opening movement of the closure element 6 the moving clamping element 20 on the stationary clamping element 18, slides with the onset the first touch of the two clamping elements Clamping element on the inclined control surface 19 of the stationary clamping element 18 and additionally generates an axial movement for the rotational movement of the shaft 5. The axial movement is complete when the game between the moving provided on the closure element Hubanschlagelement 11 and the collar 8 of the plain bearing 3 provided resting stroke stop element 9 canceled is. A positive connection is created. The Wave can no longer be moved.

If the flap is to be closed again, the Vacuum in the vacuum can 14 a force that is greater than the spring force. The linkage 15 produces a pulling force on the crank arm 16. The one explained above non-positive clamp connection is released. It starts as the closing movement progresses Closure element 6 the housing inner jacket 12 on the touch the side adjacent to the crank arm. As it progresses There is also a rotary movement Axial movement and thus an orientation for the Closure element 6, i.e. a return of the closure element in its central position. The original Axis play is restored. The closure element is again in its seal-optimized closure position. In this end position, too, there is a positive connection Connected.

When the flap is open, the flow path released and the exhaust gas flows around the closure element 6. The flowing exhaust gas creates on the closure element 6 always a force acting in the closing direction, when the closure element assumes an intermediate position.

Because positive connections are created in both end positions and in the phases of the transitions between the states "closed" and "open" the flow an additional tension is rattling a throttle valve designed according to the invention excluded. At the same time, a sufficient game can be given to both the rotary motion as well not to hinder the positional compensation of the closure element.

Claims (11)

Throttle valve unit for use in the exhaust system of an internal combustion engine, comprising a valve housing (1), a shaft (5) rotatably mounted therein about an axis (7) with a closure element (6), a vacuum box (14) with a membrane and one of the implementation coupling device serving the lifting movement of the membrane into a rotating movement of the shaft (5), a stop device limiting the rotating movement (A) of the shaft (5) in the flap position "open" being provided,
characterized in that the stop device is designed as an axially acting clamping device which comprises a stationary clamping element (18), a clamping element (20) rotatably moved with the shaft (5), an axially stationary lifting stop element (9) and a with the shaft (5) comprises axially moved stroke stop element (11), at least one of the two clamping elements (18, 20) having a control surface (19, 21) inclined to the axis (7), against which the other clamping element lies "open" in the flap position, and wherein in the flap position "open" the moving stroke stop element (11) rests on the stationary stroke stop element (9). Throttle valve unit according to claim 1,
characterized in that the coupling device comprises a linkage (15) connected to the membrane of the vacuum box and a crank arm (16) connected to the shaft (5), the rotatable clamping element (20) being part of the crank arm (16). Throttle valve unit according to claim 1 or claim 2,
characterized in that both the stationary (18) and the moving clamping element (20) have a control surface (19, 21) inclined to the axis (7). Throttle valve unit according to one of claims 1 to 3,
characterized in that the stationary clamping element (18) is associated with a mounting bracket (13) by means of which the vacuum box (14) is supported on the flap housing (1). Throttle valve unit according to one of claims 1 to 4,
characterized in that the shaft (5) is mounted in the flap housing (1) in two sliding bearings (3, 4), at least one of which is designed as a collar sliding bearing, the collar (8) of the collar sliding bearing forming the stationary stroke stop element (9) , Throttle valve unit according to claim 5,
characterized in that the moving stroke stop element (11) is formed by a collar or a shoulder of the shaft (5). Throttle valve unit according to one of claims 1 to 4,
characterized in that the stationary stroke stop element (11) is formed by the flap housing (1). Throttle valve unit according to claim 7,
characterized in that the moving stroke stop element (11) is formed by the closure element (6). Throttle valve unit according to one of claims 1 to 8,
characterized in that the closure element (6) near the axis (7) is cylindrical in shape and receives the shaft (5). Throttle valve unit according to one of claims 1 to 9,
characterized in that the shaft (5) is mounted in the flap housing (1) in two slide bearings (3, 4) which are formed from a wire mesh. Throttle valve unit according to one of claims 1 to 10,
characterized in that the closure element (6) in the flap position is closed only in its regions remote from the axis (7) against the inner wall (12) of the flap housing (1), while adjacent to the axis between the closure element (6) and the inner wall the valve housing (1) there is little play.

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