EP1418311B1 - Variable geometry vanes array for a turbocharger - Google Patents

Description

The invention relates to a variable geometry guide grid according to the preamble of claim 1.

For the adjustment of the guide vanes of a guide rail of variable geometry, the most diverse transmissions have already become known, as is known from US-A-4,179,247 or US-A-5,146,752. Especially the latter shows how cumbersome to assemble the individual parts of the guide grid on the housing, as different parts must be plugged into each other, fitted and connected together, especially when installed in a turbocharger - or at least in a turbine unit.

Now, from US-A-5,028,208 also Leitgitter become known in which sit at pivot shafts of the vanes lever whose end is provided with a fork opening. In this fork opening slides with its longitudinal axis approximately parallel to the central axis extending stone or pin, which is moved with the adjusting ring (sliding block gear). The disadvantage of this transmission is that just when the forces acting on the vanes by the gas forces exert on this the largest torque, the torque exerted by the adjusting ring is relatively low. This is also a minor problem with lower power internal combustion engines. A noticeable problem (also with regard to wear, etc.), but it is especially in internal combustion engines with higher power.

This will also be a problem with regard to the automatic adjustment, in particular for the control of a braking operation. In this regard, reference is made to U.S. Patent Nos. 5,123,246; 5,444,980 and 6,148,793, all of which provide for electronic regulations.

An adjusting using levers, ie levers that do not twist within an opening or groove, but only immerse, is known from FR-A-1.442.174, which document shows all the features of the preamble of claim 1. Although this improves the characteristic of the torque during the adjustment, many applications remain to be desired.

The invention is therefore an object of the invention to provide a connecting gear to a guide grid of the type mentioned above, which works even more reliable, especially since the adjustment moment applied to the adjusting vanes in its course during the adjustment actually corresponds approximately to the counter-torque that on the Guide vanes acts.

According to the invention, this object is achieved in a surprisingly straightforward manner by the characterizing features of claim 1, as will be explained below with reference to FIGS. 4 to 9. In fact, this achieves an almost perfect adaptation of the adjusting moment to the moments acting on the guide vanes.

In itself, the handlebar or rocker arm could be attached to the respective pivot shaft of a vane and immerse in an opening of the first link, which is mounted on the adjusting ring, as shown in the prior art. However, it has proven in experiments to be cheaper if the second link is designed as a pivotable guided on the associated ring link, and the second link dives in approximately radial direction in the opening of the first link.

The simplest embodiment of the cooperating pair of handlebar and opening could be that the handlebar is designed as a round rod, which dips into a cylindrical bore of the first adjusting member. However, this requires a very accurate guidance on a relatively short guide route. Therefore, it is preferred if the pivotable arm (drag lever) has a polygonal cross-section, possibly with rounded corners, in particular an approximately quadrangular cross-section, because the practice has shown that so that leadership problems do not occur. In this case, an additional axial degree of freedom of the link or rocker arm is given.

Of course, one has to keep in mind that all of these interacting parts have to be assembled and, if necessary, easily disassembled. Therefore, it is preferred if the opening of the first adjusting member is formed as a groove, in particular as against the guide vanes facing groove, in which one simply inserts the handlebar or cam follower in the axial direction. This makes it especially easier to use all drag levers in their associated openings.

Fig. 1

einen Turbolader in Perspektivansicht, teilweise im Schnitt, an dem die vorliegende Erfindung zur Anwendung kommt;

Fig. 2

eine Perspektivansicht eineAnordnung ähnlich dem Stande der Technik, von der die

Fig. 3

eine einzelne Verstellwelle mit Leitschaufel veranschaulicht;

Fig. 4

eine Perspektivansicht einer bevorzugten Ausführungsform der Erfindung, deren Funktion an Hand der

Fig. 5-7

näher erläutert wird;

Fig. 8

ein Teil eines leicht perspektivisch gezeigten weiteren Ausführungsbeispieles mit dem Leitschaufelkranz unter Weglassung des Schaufellagerringes; und

Fig. 9

ein Diagramm der Charakteristik des auf die resultierenden Leitschaufelmomentes bei unterschiedlichen Belastungen mit den Kurven eines herkömmlichen Turboladers und eines erfindungsgemäßen Turboladers.

Further details of the invention will become apparent with reference to the following description of schematically illustrated in the drawings embodiments. Show it:

Fig. 1

a turbocharger in perspective view, partially in section, to which the present invention is applied;

Fig. 2

a perspective view of an arrangement similar to the prior art, of which the

Fig. 3

illustrates a single Verstellwelle with vane;

Fig. 4

a perspective view of a preferred embodiment of the invention, whose function is based on the

Fig. 5-7

is explained in more detail;

Fig. 8

a part of a slightly further perspective shown another embodiment with the vane ring, omitting the blade bearing ring; and

Fig. 9

a graph of the characteristic of the resulting vane torque at different loads with the curves of a conventional turbocharger and a turbocharger according to the invention.

1, a turbocharger 1 in a conventional manner a turbine housing part 2 and an associated compressor housing part 3, along an axis of rotation R are arranged. The turbine housing part 2 is partially shown in section, so that therein a vane ring 6 a radially outer guide vane forming, circumferentially distributed vanes 7 rotated about their the vane ring 6 passing through pivot axes 8 so that they form between each nozzle cross-sections, depending on the location the guide vanes 7, namely radially (as shown) or more tangential, larger or smaller and located in the middle of the axis R turbine rotor 4 more or less with the supplied via a supply channel 9 and discharged via a central port 10 exhaust gas of a motor act on the turbine rotor 4 to drive a seated on the same shaft compressor rotor 21.

In order to control the movement or the position of the guide vanes 7, an actuating device 11 is provided. This may be of any nature in itself, but it is preferred if it, in a conventional manner, a control housing 12 which controls the control movement of a ram member attached to it 14, its movement via an adjusting gear with a crank member 16 and a drag lever 17 on a behind the blade bearing ring 6 (left behind behind in Fig. 1) located adjusting ring 5 implement the same in a slight rotational movement. the details of this linkage will be explained later.

As a result of this rotational movement, the guide vanes 7 are adjusted relative to the turbine rotor 4 with respect to their rotational position via the shafts 8 in such a way that they can be adjusted from an approximately tangentially extending one extreme position into an approximately radially extending other extreme position. As a result, the exhaust gas supplied via the supply channel of an internal combustion engine is supplied more or less to the turbine rotor 4, before it exits again at the axial connection piece 10 extending along the axis of rotation R.

Between the vane ring 6 and an annular part 15 of the turbine housing part 2 remains a relatively narrow space 13 to allow the blades 7 a free mobility. Of course, this blade space 13 may not be much larger than the width of the blades 7, because then the exhaust gas energy would suffer leakage. On the other hand, the blade chamber 13 may not be too tight, because then the blades 7 could jam.

In Fig. 2 is indicated by dash-dotted lines to illustrate the interaction of the blade bearing ring, so that behind the rocker arm 17 sees immersed in circular holes 18. The drag levers 17 are mounted in each case by means of pivot pins 19 on the adjusting ring 5 and extend in each case in an approximately radial direction (from which direction, however, they swivel out slightly in each case after the one and the other side). The adjusting ring 5 is driven here in place of a pneumatic control housing by an electric motor 12 'from a slight rotational movement around the central axis R. The electric motor 12 'can be part of a control circuit as described in one of the above-mentioned US Pat. Nos. 5,123,246; 5,444,980 and 6,148,793 is described, which operate substantially with Kennparametern the internal combustion engine. However, it may be advantageous to include in the control loop as well as the temperature of a catalyst as a parameter, for example, a turbocharger bypass bypass by-pass, be it via the exhaust manifold of the engine directly connected to the catalyst by-pass line or via a so-called wastegate to connect with the catalyst (to heat it up quickly after the start). This is an independent of the other features described here invention. Thus, the hot exhaust gas to avoid cooling in the turbocharger can be fed directly to the catalyst for heating. The algorithm or linkage of the measured temperature value with the engine specific values may involve fuzzy control or a neural network - i. So a weighty function - be.

As can be seen particularly with reference to FIGS. 5-7, so that the pivot pin 19 is displaced by a certain angle relative to the stationary arranged pivot shafts 8, on which the guide vanes 7 sit. But so that the pivot shafts are pivoted with a special movement and torque characteristics within the blade bearing ring 6. It turns out that the maximum surface pressure of rocker arm 17 on the surfaces of the opening 18 and vice versa is relatively low, so that the wear and tear low and the reliability is high. Because the pressure is always at least approximately perpendicular to the respective surface, so that no one-sided load.

The adjusting ring 5 is a relatively narrow ring whose inner boundary in the illustration of FIG. 2 is located approximately where the dash-dotted contour 6 'of the blade bearing ring 6 can be seen. Thus, the adjusting ring can be mounted and centered on the ends of the pivot shafts 8. Since, however, because of the transmission ratio between the adjusting ring 5 and adjusting 8, the latter rotate faster than the adjusting ring 5, it is advantageous to attach a freely rotatable bearing roller 22 at the ends of at least a portion of the pivot shafts 8, as can be seen particularly in FIG ,

The fact that the drag levers 17 are mounted on the adjusting ring 5, results in a simple and easily manufacturable form of the unit of vanes 7 and pivot shafts 8, as Fig. 3 illustrates. Of course, but also a reverse arrangement would be conceivable by a gate member corresponding to the part 16 arranged in place of the pivot pin 19 and the rocker arms 17 would protrude at right angles from the pivot shafts. However, this would make the manufacture of the unit shown in FIG. 3 more complicated.

While in the arrangement of FIGS. 2 and 3, the interspersed by the rocker arms 17 openings 18 are formed by circular holes (which is also possible in the invention), will be shown on the basis of the following figures, an embodiment of the one Gate forming part 16 provided, one-sided open groove 18 'applies. This embodiment has proven particularly useful in practice and is therefore preferred. In the following figures, parts of the same function have the same reference numerals as in the previous figures, parts of similar function each have the same reference numerals, but with an addition.

In Fig. 4, the rings 5 and 6 and a mounting ring 23 can be seen. Between the mounting ring 23 and the blade bearing ring 6, the blade chamber 13, in which the ring of vanes 7 is housed around the central axis R extends. In the vane bearing ring 6, the pivot shafts 8 (see FIG. 3), which are not visible here, are in turn mounted, which are preferably formed in one piece with the respective vane 7, as illustrated in FIG.

At the left in Fig. 4, left from the blade bearing ring 6 projecting end of the pivot shafts, a backdrop forming part 16 'is again provided, however, a transverse to its pivot axis, against the adjusting ring open groove 18', which has the forms the respective rocker arm 17 receiving opening. Particularly in this embodiment, the drag levers 17 can press with flat surfaces on the inner surface of the groove 18 'and are thus exposed to a uniform, low pressure F. In order to obtain these flat surfaces, it is advantageous if the respective rocker arm 17, which is pivotable about the pivot pin 19, has an angular cross section, possibly with rounded corners, in particular an approximately quadrangular cross section.

The function of this transmission will now be explained with reference to FIGS. 5-7. Here, in each of the figures, only a single link member 16 is shown in various positions together with the associated rocker arm 17. Moves the adjusting ring 5 in the direction of the arrow a (clockwise), it can be seen from a comparison of FIGS. 5 to 7 that the pivot lever 17 pivot about its pivot point 19 in a clockwise direction. This latter pivoting makes in the present example about 40 °, while the pivoting movement of the adjusting ring 5 is much smaller. Thus arises - depending on the consideration - an over- or a reduction effect.

In the position according to FIG. 5, for example, the lower end face 17 a of the drag lever 17, which is approximately rectangular in cross-section, terminates flush with the outer face of the link part 16. The introduction of force is low and the cam follower 17 thus completely covers the opening formed as a groove 18 '. This groove 18 'is remote from the vanes, not shown, but constructions would be conceivable in which they face the vanes, but such constructions are more complicated and space consuming and therefore not preferred.

Moves the adjusting ring 5 in the direction of arrow a by about 20 ° in a central position of FIG. 6, the drag lever dives deeper into the groove 18 ', ie the force is greater, and the reaction force F _r (ie the surface pressure between the Inside the groove 18 'and the outside of the drag lever 17) corresponding to the force arrows F _r shown, due to the closing guide grid, steadily higher. In this position, the rocker arm 17 is approximately radially aligned with respect to the central axis R (see Fig. 2) and the distance of its end surface 17a from this central axis R is the lowest. By the way, with reference to the cylindrical roller 22 (see Fig. 3) in Fig. 6 also good to see how the adjusting ring 5 on this cylindrical roller (and of course all other, not shown here cylindrical rollers) is mounted. This is thus advantageously an anti-friction bearing of the adjusting ring 5.

Upon further rotation of the adjusting ring 5 by about another 20 °, the position of FIG. 7 is reached. Since the training in this embodiment is symmetrical (which, as will be explained later, is not absolutely necessary), here again, the end face 17a closes flush with the outer surface of the link member 16, ie the inner surface of the groove 18 'between the two arrows F _r (FIG. 7) is still fully utilized for transmitting the surface pressure. In the rotation of Fig. 6 to Fig. 7 induced but the maximum pressure gradient M _D, the maximum surface pressure F _r between the inner surface of the groove 18 'between the two arrows F _r and the outer surface of the cross-section preferably square rocker arm.

Of course, the above explanations apply analogously to an embodiment with a circular borehole 18 according to FIGS. 2 and 3; but they also apply substantially in the case of a reverse arrangement in which the drag levers 17 are fixed to the part 16 supporting the pivot shaft 8 and immersed in an opening of the part 16 corresponding part, which is provided instead of the pivot pin 19. But it is also understandable why it is advantageous, the rocker arm 17 in cross section square, in particular square, (possibly with rounded corners) form, because yes then the surface pressure acts at all points perpendicular to the surface.

From the function shown above it can be seen that although the cross-sectional shape of the finger lever 17 is preferably a quadrangular, but that other cross-sectional shapes are conceivable without changing the basic function. For example, a (non-preferred) hexagonal cross-sectional shape would be conceivable. Furthermore, it would be conceivable that the drag levers 17 are formed approximately T-shaped, wherein the crossbar of the T as a covering surface over the end face of the guide member 16 is located and a the trunk of the T-forming rib in the groove 18 'engages. However, this would increase the axial dimension and would also bring a more difficult to manufacture form with it.

The positions of the vanes 7 associated with the positions of the rocker arms shown in FIGS. 5-7 can best be derived from FIG. 8, which shows a variant with cranked rocker arms in a position which approximately corresponds to that of FIG. 5 (closed position) the vanes 7, maximum moment acting on them). It can be seen that the closed position of the guide vanes 7 (approximately during braking operation) is achieved approximately when the fork 28 is at least almost parallel to a median plane P3. However, the invention is not limited thereto; Rather, the fork 28 may instead of mutually parallel forks also curved have, if a particular modification of the characteristic is desired.

In Fig. 8, the adjusting ring 5 is mounted on (not shown) the blade bearing ring 6 fixed bearing rollers 24 and so slightly further away from the pivot shafts 8, so that the length of the drag lever 17 is increased compared to the previous embodiments. Similarly, in the case of using cylindrical rollers 22 for supporting the adjusting ring 5 distributed over the circumference, for example, only three such rollers 22 may be provided. However, if you want to use instead of the bearing rollers 24, the cylindrical rollers 22 (Fig. 3), this leads to problems in the use of a groove 18 'as an opening. In this case, either the above the level of the respective tow lever 17 extended, the groove 18 'limiting segment parts serve as a bearing for the cylindrical roller 22 (which is not always advantageous), or - based on Fig. 3 - it assigns the cylindrical roller 22 instead of the guide vane 7 facing away from the end face of the guide member 16 and the guide vane 7 facing end face of the link member 16, in which case the cam followers 17 would cooperate with the grooves 18 'on the side facing away from the vane ring 6 of the adjusting ring 5, while the adjusting ring 5 itself would be supported on the cylindrical rollers 5 thus arranged. It can be seen, therefore, that the use of the rotatable about the axis of the respective pivot shaft 8 cylindrical rollers 22 - wherever they are arranged - results in an advantageous storage of the adjusting ring 5 and therefore represents a separate invention, regardless of the use of a finger lever mechanism.

The adjusting ring 5 has attached at its periphery a square sliding block 25 which is pivotable about a rotation axis 26. At this sliding block 25 engages a pivotable with a shaft 27, the associated backdrop forming fork 28 at. An adjustment arm 29, which is pivotable about the geometric axis of the shaft 27 either from the plunger 14 of the control housing 12 (see Fig. 1) or from the servo motor 12 ', is attached to the shaft 27 in order to adjust the adjustment ring 5 via the fork 28 to pivot about the central axis R.

Notwithstanding previous embodiments with rocker arms 17, whose longitudinal axis A passes through the pivot point 19, slightly cranked rocker arm 17 'are provided here, which have proven to be particularly favorable. The offset is dimensioned such that two planes P1, P2 through the central axis R together form an angle β. This angle β is relatively small and should be at most 12 °, but is preferably below it, so that it is a maximum of 9 °. In practice, an angle β of at most 6 °, e.g. about 2 ° found to be particularly favorable.

The offset can also be defined as the angle φ between the plane P2 passing through the geometric axis of the pivot shafts 8 and the central axis R and the longitudinal axis A of the drag levers 17 '. This angle φ will be large at a small pressure gradient in the space 13 (FIG. 1) and decreases with the increase in the load acting on the guide vanes 7 (ie FIG. 8 shows the smallest angle φ occurring in this embodiment). It is therefore understandable why it is preferable to select the mutual angular position of the respective opening 18 or 18 '(which coincides with the direction of the longitudinal axis A), that in the closed position of the guide vanes 7 shown in FIG. Braking operation), the longitudinal axis A of a drag lever 17 'to the radial plane P2 on the central axis R assumes a non-zero angle φ (because in an orientation of the longitudinal axis A on this radial plane in this position of the guide vanes 7 of the force or torque curve would be unfavorable) , Of the Angle φ is to be selected for the respective construction (occurring forces, surface pressure between opening 18 or 18 'and outer surface of the drag lever, available actuating forces), but should preferably be between 25 ° and 15 °, for example at approximately 20 °. In the present embodiment, it is slightly between 21 ° and 22 °, that is in the preferred range of 20 ° ± 2 °.

Another definition can be achieved by the offset angle γ between the longitudinal axes A, A 'extending through the bent sections of the finger lever 17. This angle γ should be in the range of 170-120 ° and preferably about 140 °.

As can be seen in particular from FIG. 9, significantly more force can be induced with this arrangement, which means that the rotary actuator (12 or 12 ') actuating the lever 29 is considerably relieved. In this case, however, a certain loss of power must be accepted in the braking point (closed guide grid), which corresponds to a value of [1-cos (6 °)] = 0.547% and thus is vanishingly small at an angle β of 6 °. In such cranked rocker arms 17 'is - based on the positions shown in FIGS. 5-7 - is implemented in the range between the positions of Fig. 6 and 7 more adjustment at lower power. However, the more the position of the drag lever 17 'approaches that which corresponds to FIG. 5, the greater the force. Measurements have shown that with just opened by 3 ° vanes 7, the moment acting on them already by more than 30% (measured 31.25%) drops. However, this nominal characteristic for a transmission is particularly taken into account by the rocker arm transmission according to the invention, and in particular that according to FIG. 8.

FIG. 9 shows the characteristic profile of a conventional guide grid c ₁ in a turbocharger in comparison with the course c ₂ in a guide grid according to the invention. In this case, the blade moment M _S in Nm is compared with the adjustment angle α of the adjusting lever 29 receiving the moments (FIG. 8). It can be seen that the largest moment M _S at 0 ° (di relative to the radial orientation -20 °), thus thus just reached when the guide vanes 7 and the lever 29 are in the position shown in Fig. 8 and the have to withstand the greatest moment affecting them. To the right, on the other hand, the moment decreases sharply, but never reaches a zero value up to 40 ° (ie, + 20 ° relative to the radial orientation) (must not). It should also be noted that the curve c ₂ soon after its intersection D2 (end of the work area) on a moment of zero decreases and thus lies within the working range between zero load (in the point D2) and braking load (left upper point) approximately symmetrical, which represents a further advantage of the construction according to the invention. For comparatively had in the known construction with the characteristic c _{1 of} the lever 29 to drive through a slightly larger path of almost 43 °, but also came much later than the curve c ₂ on the X-axis, whereby the characteristic c ₂ a clear asymmetry had. This was also expressed by the fact that the maximum moment which the known construction could withstand was not at angle α = 0, but at about 5-6 °. In addition, the displacement angle for the curve c _{1 is} smaller than at c ₂ .

In the context of the invention numerous variants are possible; For example, the guide vanes according to the invention need not necessarily be used in turbochargers, but could also be used for other turbines or for secondary air pumps.

LIST OF REFERENCE NUMBERS

1

turbocharger

3

Compressor housing part

5

adjusting

7

vanes

9

supply channel

11

actuator

13

blade space

15

Part v. 2

17

cam follower

19

pivot pin

21

compressor rotor

23

mounting ring

25

sliding block

27

wave

2

Turbine casing

4

turbine rotor

6

Nozzle ring

8th

pivot shafts

10

central (axial) connection

12

control housing

14

plunger member

16

link part

18

drilling

20

drive arm

22

bearing roller

24

bearing roller

26

axis of rotation

28

fork

Claims (8)

1. Guiding grid of variable geometry in particular for a turbocharger (1), comprising:

   a crown of guiding vanes (7) arranged around a central axis (R), each vane being pivotal by means of a pivoting axis (8);

   a nozzle ring (6) for supporting said vanes (7) and their pivoting axes (8) around said central axis (R);

   a unison ring (5) which is pivotable around said central axis (R) relative to said nozzle ring (6); and

   a transmission mechanism (16-19) through which said unison ring (5) is connected to said vanes (7) for pivoting of their angular directions by means of their respective pivoting axes (8), having a first connection element with an opening (18) in which a second connection element (17) is slidably guided,

   said second connection element (19) being in form of a drag lever (17) which is pivotably guided on an associated ring and said drag lever (17) immerging into said opening (18) of the first connection element (16) in approximately radial direction, characterized in that said pivotable drag lever (17) has a longitudinal axis (A,A') which is bent off with respect to its articulation point (19), the bending angle (β) being preferably selected so that planes (P1, P2), going through the central axis (R) as well as, on the one hand, through the middle of each respective pivoting axis (8) and, on the other hand, through the articulation point (19) of a drag lever (17), include an angle of at most 12°, preferably at most 9°, in particular at most 6°, e.g. 2°, and that angle (γ) between the longitudinal axes of the bent sections of the drag lever (17) is 170° to 120°, preferably 140°.
2. Guiding grid as claimed in claim 1, characterized in that said pivotable drag lever (17) is articulated on said unison ring (5).
3. Guiding grid as claimed in claim 1 or 2, characterized in that said pivotable drag lever (17) has a cornered cross-section, e.g. with rounded corners, preferably with a generally square cross-section.
4. Guiding grid as claimed in any one of the preceding claims, characterized in that said pivotable drag lever (17) abuts, essentially in all its positions, on the entire length of the inner surface of opening (16, 16').
5. Guiding grid as claimed in any one of the preceding claims, characterized in that the transmission mechanism with its drag lever (17), which is located between the nozzle ring (16) and the unison ring (5) includes at least one of the following characteristics :

   a) the respective drag ring (17) is supported on the unison ring (5) by means of a pivoting pin (19) and enters into opening (18) of the first connection element (16) which is provided on the associated pivoting axis (8) for a vane (7);

   b) the unison ring (5) is arranged radially outwardly from the pivoting axes (8) which are supported on the nozzle ring (6).
6. Guiding grid as claimed in any one of the preceding claims, characterized in that the opening of the first transmission element (16') is in form of a groove (18'), in particular a groove which looks away from the vanes (7).
7. Guiding grid as claimed in any one of the preceding claims, characterized in that on at least some of the pivoting axes (8) is provided a support surface for the unison ring (5), which is preferably presented by a support roll (22).
8. Guiding grid as claimed in any one of the preceding claims, characterized in that the longitudinal axis (A) of each of the drag levers (17) forms an angle (δ), different from 0°, with a radial plane (r) when the vanes (7) are closed, of preferably 15° to 25°, in particular about 20°+/- 2°.

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