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Radial swivel motor and process for manufacturing same

Radial swivel motor and process for manufacturing same description/claims

This application is a U.S. National Phase application of International Application PCT/DE 2005/000681 and claims the benefit of priority under 35 U.S.C. § 119 of German Patent Application DE 10 2004 020 190.0 filed Apr. 22, 2004, the entire contents of which are incorporated herein by reference.

The present invention pertains to a swivel motor according to the preamble of claim 1 and to a corresponding manufacturing process according to the preamble of claim 7

Such swivel motors are used especially in the aircraft and automobile industries to perform a great variety of tasks. A preferred field of application is in the vehicle industry, where the swivel motor is used for the roll stabilization of a motor vehicle in conjunction with stabilizers.

Such a swivel motor is described, for example, in DE 197 25 412 C2. This swivel motor comprises a stator, which is connected to a first stabilizer part, and a rotor, which is in connection with a second stabilizer part. The stator has two radially directed stator blades and the rotor has two, likewise radial rotor blades. The two stator blades and the two rotor blades form, in conjunction with two front-side covers, two hydraulic working chambers, which are located opposite each other, so that the stator blades and the rotor blades can be pivoted in relation to one another against the hydraulic load in one of the two working chambers.

For the inner sealing of the two working chambers between them, each stator blade is equipped with a frame sealing element, which is inserted into the stator blade and is sealingly in contact with the outer circumference of the rotor, while each rotor blade carries an identical frame sealing element, which is sealingly in contact with the inner circumference of the stator.

The stator and the two stator blades are made in one piece, so that the inner surfaces have a complicated contour. These inner surfaces have different tasks to perform, the lateral surfaces of the stator blades being designed for a pure stop function, whereas the inner circumferential surfaces of the stator act as sliding and sealing surfaces.

A cold-extruded tube, which is first turned to the corresponding lengths of a stator housing, is used as the blank for manufacturing such a stator under mass production conditions. The inner contour of each blank is then finished by the manufacturing process broaching in three passes. The surface finish of Rz=10 that can thus be attained at best is sufficient for the stop function. This finish is unsatisfactory for the sliding and sealing function of the inner circumferential surfaces of the stator because a surface finish of Rz=1.0 to 2.0 is usually required herefor.

Therefore, a swivel motor equipped with such a stator fails to reach its performance parameters because the inner sealing between the pressurized working chamber and the pressureless working chamber cannot be guaranteed due to the roughness of the sealing surfaces. Because of the rough surface of the stator, the frame sealing elements are also subject to greater wear, so that the swivel motor also has a limited service life only. Furthermore, the manufacture of such a stator especially by the broaching process is very complicated in terms of manufacturing technology and expensive.

To improve the sealing function, attempts were already made to improve the surface finish by a subsequent lapping. There also were efforts to develop frame sealing elements that adapt themselves to the rough surface. All these attempts failed ultimately because of the high costs or the limited installation conditions.

The basic object of the present invention is therefore to improve the surface finish of the inner circumferential surfaces of the stator of a swivel motor of this class and to reduce the effort needed for manufacture at the same time.

According to the invention, a radial swivel motor is provided comprising a stator with at least one, radially inwardly directed stator blade and a rotor mounted in the stator with rotor blades. The rotor blades form between the rotor and the stator at least one hydraulic, variable-volume pressure chamber and just as many hydraulic, variable-volume drain chambers. Frame sealing elements are in the stator blades and in the rotor blades. The pressure chambers and the drain chambers are sealed hydraulically against each other by the frame sealing elements in the stator blades and the rotor blades. The stator has a multi-part design comprising a stator housing and the stator blade. The stator blade is inserted into the stator housing in such a way that the stator housing and the stator blade rotate in unison.

The stator housing may have, for each stator blade, a longitudinally extending mounting slot. Each stator blade may then have a mounting tongue fitting the mounting slot. The stator housing and the mounting tongue of the stator blade may be connected to one another by a weld seam prepared on the outer circumference of the stator housing.

To form a groove for the weld seam, the mounting slot of the stator housing and the mounting tongue in the stator blade may have circular conical surfaces.

The stator housing may have, for each stator blade at least one longitudinally extending wedge-shaped groove. Each stator blade may have an outer shape fitting the wedge-shaped groove. The wedge-shaped groove and the outer shape of the stator blade may have such external dimensions that clamping and self-locking pressing are achieved and have a cross section with a dovetail profile.

For mutual bracing, the stator housing and each stator blade may have fastening holes. The stator housing may be provided with a fitting groove and each stator blade may be provided with a fitting tongue to mutually secure the positions. Each stator blade may carry at least one sealing element extending over its entire length to guarantee sealing between the pressure chamber and the drain chamber.

For securing against rotation, the stator housing may have at least one position-securing groove extending over the entire axial length for each stator blade. The stator blade may be designed in its outer area as a fitting tongue. Each stator blade may have a wedge-shaped design over an entire axial length thereof in the area of lateral surfaces thereof for clamping and self-locking frictional engagement. A spacer shell having lateral surfaces extending in a wedge-shaped pattern may be inserted on one side and on the other side between two stator blades.

According to another aspect of the invention, a process is provided for manufacturing a radial swivel motor. The process includes providing a rotor; providing stator covers providing individual stator blades and providing sealing elements. A commercially available tube bar material is cut to a length with an inner circumferential surface suitable for use as a sealing surface to manufacture a stator housing. The inner contour of the inner circumferential surface is prepared and front surfaces are finally leveled off and provided with recesses for the sealing elements and with holes for fastening the stator covers. The stator is assembled nondetachably from the stator housing and the individual stator blades. Each stator blade is manufactured with a finished contour providing longitudinally extending joining means fitting the stator housing.

The stator housing may have the mounting slots and each stator blade may have mounting tongues. The tongues are inserted into the slots and are welded together in the assembled state on the outer surface of the stator housing.

The stator housing may have wedge-shaped grooves and each stator blade may have a wedge-shaped outer shape. The wedge-shaped outer shape is pressed into a groove together with the stator housing into a respective one of the grooves in the assembled state on the outer surface of the stator housing.

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