Drive device for pivoting adjustable blades of a turbomachine

Abstract

A drive device for pivoting adjustable blades of a turbomachine is provided. The drive device includes an annular flow channel section surrounded by a blade carrier, the section extending along the center line of the blade carrier and blades being provided in the section in a ray-like manner, forming a ring, wherein each of the blades can be pivoted about the longitudinal axis thereof and each has a pin which extends at least into the blade carrier and is coupled to at least one adjustment ring which encloses the blade carrier and may be driven by means of at least one motor. In order to provide a particularly low-wear and reliable drive, the drive shaft of the motor or motors is coupled to the adjustment ring or adjustment rings by means of a pinion gear.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is the US National Stage of International Application No. PCT / EP2011 / 052188, filed Feb. 15, 2011 and claims the benefit thereof. The International Application claims the benefits of European Patent Office application No. 10001722.7 EP filed Feb. 19, 2010. All of the applications are incorporated by reference herein in their entirety.FIELD OF INVENTION[0002]The invention refers to a drive device for the pivoting of adjustable vanes of a turbomachine, with an annular flow passage section which is encompassed by a vane carrier, extends along the center axis of the vane carrier, and in which vanes are provided in a radial manner, forming a ring, wherein the vanes are pivotable in each case around their longitudinal axis and have in each case a pivot pin which extends at least into the vane carrier and is coupled to an adjustment ring which is rotatable in the circumferential direction.BACKGROUND OF INVENTION[0003]A device of ...

AI Technical Summary

Benefits of technology

[0010]According to this, the object of the present invention is the creation of a wear-free, reliable drive device—suitable for fast, smaller adjustments—for temperature-independent adjustment of the vanes which extend radially in an annular passage and are rotatable around their respective longitudinal axis.

[0015]In addition to the compact and light-weight construction on account of using a larger number of motors, a further advantage lies in the greater adjustment speed which the drive device now enables for the first time. The transmission of force from the motors to the directly driven vanes is carried out without backlash and to the remaining vanes almost without backlash. In conjunction with the compact construction and the comparatively low masses which are to be moved, the vanes can also be adjusted by comparatively small angle values in a comparatively short time. The known gear drives, however, always provide that all the vanes are driven indirectly via the adjustment ring.

[0020]According to a further advantageous development, provision is made in the vane carrier or in the casing encompassing the vane carrier for a circumferential groove on the generated surface side, in which the pivot pins end and in which the adjustment ring is arranged, wherein for the shielding of pivot pins, adjustment ring and their coupling the circumferential groove is closed off to the outside at least for the most part by means of a cover. The coupling of adjustment ring and pivot pin is therefore embedded in the vane carrier or recessed in the circumferential groove, as a result of which a two-sided shielding is created, as seen in the longitudinal direction of the turbomachine. With this advantageous embodiment, it departs from the prior art in which the adjustment mechanism was previously arranged outside the casing of the turbomachine without protection. It is now provided that the adjustment mechanism is at least covered, if not even hermetically sealed, as a result of which the drive for the most part (that is to say except for the lead-through for the drive shaft of the motor) is relocated into the wall of the vane carrier. This requires that the vane carrier, in the region in which the pivot pins project into it, is of at least such thickness there that a circumferential groove for accommodating the pivot pin ends and the adjustment ring can be introduced there from the outside, for example by means of mechanical machining. The covering of the circumferential groove by means of a plurality of cover segments is simple to achieve in this case, wherein the fastening of the cover, or cover elements, can be carried out by conventional means, such as by screws. A simple construction, which can be comparatively simply and also inexpensively realized, can be realized with this.

[0022]An especially simple and reliable supporting of the adjustment ring can be achieved if this—with regard to the center axis of the vane carrier—is guided radially on the outside by the cover of the circumferential groove and radially on the inside by the groove base of the circumferential groove. The cover then also serves as a guide for the adjustment ring since this bears in a slidable, but clearance-free, manner both on the cover and on the groove base. This avoids the use of additional construction elements such as support rollers for the central supporting of the adjustment ring in relation to the machine axis. This embodiment also enables a comparatively thin adjustment ring since its natural rigidity can now be lower than previously.

[0024]In order to prevent gaping of the toothing, the adjustment ring is axially guided by a sidewall of the circumferential groove, with regard to the center line of the vane carrier. Alternatively or in addition thereto, it can be provided that means for pressing the adjustment ring onto the pivot pins are provided in the sidewall or between sidewall and adjustment ring. For example, passages for the feed of a hydraulic medium can open into the sidewall for this purpose. It is also possible that provision is made between the sidewall and the adjustment ring for spring elements, also uniformly distributed over the circumference, which exert an axially acting force upon the adjustment ring. As a result of using a toothing arrangement, the adjustment ring can be of thinner design than the comparatively solid adjustment ring from the prior art for stationary gas turbines. By pressing the adjustment ring onto the pivot pins, the elimination of the tooth flank clearance can also be carried out in order to thus keep the adjustable vanes free from play in their predetermined position during operation of the turbomachine. If necessary, the pressing-on force can be reduced during the adjustment process, which is easily possible especially when a hydraulic medium is being used as the pressing-on means. In this case, the adjustment process can be accomplished with comparatively small forces.

Problems solved by technology

In this case, the drives which are known from U.S. Pat. No. 5,549,448 and EP 1 524 413 A2 are costly in construction since a large number of components are necessary and are to be designed.

The large number of components lead to a time-consuming assembly during manufacture, which, on account of the required accuracy of the position of the rotation angle of the individual vanes, is additionally time-intensive, moreover.

These temperature differences can lead to unequally set incidence angles of the vanes of the vane ring so that care is always to be taken that the adjustment ring and the vane carrier are mounted coaxially or concentrically to a common center axis.

In addition, the tangential force application via push rods can also bring about a similarly disadvantageous decentering of the adjustment ring.

Also, the bearing arrangement of the known adjustment rings can be susceptible to contaminants and malfunctions, which limit a reliable and stable operation.

In particular, in the worst case foreign bodies can cause blocking of the drive device in in the region of the toothing arrangement in the case of the embodiment according to GB 1 466 613 or in the region of the lever in the case of the embodiment according to U.S. Pat. No. 5,549,448 or EP 1 524 413 A2, which then substantially limits the operating range of the turbomachine.

This, however, is not possible with the conventional, known systems.

The lever systems on the one hand are sluggish on account of the solid constructions of adjustment rings and levers.

Fast changes with a small adjustment distance lead to enormous loads in the adjustment rings, which can put the reliability and the integrity of the drive device at risk.

On the other hand, the lever systems have tolerance-related clearances in the lever linkages so that a slight adjustment cannot be executed as a result.

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