US20080124229A1

US20080124229A1 - Radial Swivel Motor and Process for Manufacturing Same

Info

Publication number: US20080124229A1
Application number: US11/568,215
Authority: US
Inventors: Stefan Beetz; Winfried Krueger; Torsten Baustian; Joachim Uecker
Original assignee: ZF Friedrichshafen AG
Current assignee: ZF Friedrichshafen AG
Priority date: 2004-04-22
Filing date: 2005-04-14
Publication date: 2008-05-29
Also published as: EP1738081B1; DE502005005811D1; JP2007533903A; CN101031727A; EP1738081A1; DE102004020190A1; ATE412827T1; KR20070002087A; WO2005103503A1

Abstract

To improve the surface finish of the inner circumferential surfaces of the stator and to reduce the manufacturing effort, it is proposed that the stator with a stator housing 1 and with the stator blades 13 have a two-part design and to insert the stator blade 13 into the stator housing 5 in such a way that they rotate in unison. In terms of the process, it is proposed that a commercially available tube with an inner circumferential surface suitable for use as a sealing surface be used and that longitudinally extending joining means be prepared. The stator blades 13 manufactured as an individual part receive corresponding joining means, so that the stator housing 5 and the stator blades 13 are welded, clamped or screwed together.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

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.

FIELD OF THE INVENTION

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

BACKGROUND OF THE INVENTION

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.

SUMMARY OF THE INVENTION

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.
The stator housing may have the fastening holes and the fitting grooves and each stator blade may have fastening holes and a fitting tongue, which are screwed together in the fitted state on the outer surface of the stator housing.
A commercially available tube may be used without special requirements on the surface finish of the inner circumferential surface, to manufacture the stator housing. The stator housing may have position-securing grooves. Each stator blade may receive an outer shape coordinated with the position-securing grooves as well as lateral wedge surfaces. A spacer shell with lateral wedge surfaces may be inserted between two stator blades. The stator blades and the spacer shells may be pressed together on their wedge surfaces in a self-locking manner.
The novel swivel motor and the novel manufacturing process eliminate the drawbacks of the state of the art.
The present invention will be explained in more detail on the basis of a number of exemplary embodiments. The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which preferred embodiments of the invention are illustrated.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a longitudinal sectional view of a radial swivel motor;

FIG. 2 is a cross sectional view of a first embodiment of the swivel motor;

FIG. 3 is a perspective view of the stator housing according to FIG. 2;

FIG. 4 is a perspective view of a stator blade according to FIG. 2;

FIG. 5 is a cross sectional view of a second embodiment of the swivel motor;

FIG. 6 is a perspective view of a form of the stator housing according to FIG. 5;

FIG. 7 is a perspective view of another form of the stator housing according to FIG. 5;

FIG. 8 is a perspective view of a stator blade according to FIG. 5;

FIG. 9 is a perspective view of the stator housing according to a third embodiment of the swivel motor;

FIG. 10 is a perspective view of a stator blade of the third embodiment;

FIG. 11 is a cross-sectional view of a fourth embodiment of the swivel motor; and

FIG. 12 is a perspective view of the stator according to FIG. 11.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings in particular, According to FIG. 1, the swivel motor comprises a stator 1 and a rotor 2, the stator 1 being connected to a first stabilizer part 3, on the one hand, and the rotor 2 being connected to a second stabilizer part 4, on the other hand.
The stator 1 comprises a cylindrical stator housing 5, a first stator cover 6 arranged on one side of the stator housing 5 and a second stator cover 7 located on the other side of the stator housing 5. Both stator covers 6, 7 are rigidly screwed to the stator housing 5 and equipped with a through bearing bore each. A rotor shaft 8 of the rotor 2 is rotatably fitted into the bearing bores of the two stator covers 6, 7, which the bearing bores are located opposite each other, and hydraulically sealed against the two stator covers 6, 7 by means of corresponding sealing elements 9, 10.
As is shown in FIGS. 2, 5 and 11, the rotor 2 has two rotor blades 11, which are located opposite each other. These rotor blades 11 are made in one piece with the rotor shaft 8 and are coordinated with their radially directed heads with the inner wall of the stator housing 5. Each rotor blade 11 is equipped for this purpose with a groove-like recess, which extends over its entire axial length and is inserted into a frame sealing element 12. This frame sealing element 12 consists in the known manner of a plastic with an elastomeric core and a circular sealing frame, preferably one made of PTFE. This frame sealing element 12 is sealingly in contact by one of its long legs with the inner circumferential surface of the stator housing 5 and by its two short legs with the two stator covers 6, 7.
Two stator blades 13, which are located opposite each other and are likewise provided with a groove-like recess extending over the entire axial length of the stator housing 5, are inserted into the stator housing 5. A frame sealing element 12 each, which is sealingly in contact by one of its long legs with the outer circumferential surface of the rotor shaft 8 and by its two short legs with the two stator covers 6, 7, is also fitted into this recess. Two pressure chambers 14, which are located opposite each other and are under equal pressure, and two drain chambers 15, which are located opposite each other and are under equal pressure, whose volumes are variable due to the limited relative pivotability between the stator blades 13 and the rotor blades 11, are thus formed. The equality of pressures in the respective working chambers 14 and drain chambers 15 located opposite each other is achieved through the connection channels 16 prepared in the rotor shaft 8.
The stator housing 5 and the two stator blades 13 have a two-part design in a special manner.
Thus, the stator housing 5 is designed in a first embodiment according to FIG. 3 as a tube and has two longitudinally extending mounting slots 17 of a limited length, which are located opposite each other, for the two stator blades 13. Each stator blade 13 according to FIG. 4 is correspondingly provided with a longitudinally extending mounting tongue 18. Each mounting slot 17 has a circular conical surface, which becomes larger in the radial direction from the internal diameter towards the external diameter of the stator housing 5. By contrast, each mounting tongue 18 of the stator blade 13 has a circular conical surface, which tapers in the radial direction from the inside to the outside. The internal dimensions of the mounting slot 17 and the external dimensions of the mounting tongue 18 are coordinated with one another such that the smaller dimensions of the mounting slot 17 and the larger dimensions of the mounting tongue 18 can fit each other. The cone angle is selected to be such that a groove suitable for a weld seam 19 is obtained in the fitted state.
In a second embodiment according to FIGS. 5 through 8, the tubular stator housing 5 has two wedge-shaped grooves 20, which are located opposite each other and extend over the length of the stator housing 5. The wedge-shaped grooves 20 have, moreover, a dovetailed cross section. Fitting this, the stator blade 13 according to FIG. 8 is provided with external dimensions that make it possible to push the stator blade 13 axially into the corresponding wedge-shaped groove 20 and prevent falling out of the wedge-shaped groove 20 radially. The wedge angles of the wedge-shaped grooves 20 and of the outer shape of the stator blade 13 are equal and are selected to be such that a clamping and self-locking frictional engagement becomes established. As is shown in FIG. 7, clamping and self-locking frictional engagement can be achieved between the stator housing 5 and each stator blade 13, analogously hereto, by two parallel wedge-shaped grooves 20′ directed in the same direction in the stator housing 5 and wedge tongues corresponding hereto in the stator blade 13.
In a third embodiment according to FIGS. 9 and 10, the two stator blades 13 are screwed to the tubular stator housing 5 and additionally secured in their position. The securing in position is achieved by means of a fitting groove 21 in the stator housing 5 and by a fitting tongue 22 at the stator blade 13. Instead of the tongue-and-groove securing, pin-and-hole securing may also be performed.
To ensure sealing between the working chambers on both sides of the stator blade 13, each stator blade 13 is equipped with at least one longitudinal groove for a sealing element 23.
In a fourth embodiment according to FIG. 11, the tubular stator housing 5 has, for each stator blade 13, a position-securing groove 24 extending over the entire axial length, whereas the stator blade 13 is designed in its outer area as a fitting tongue. The position-securing groove 24 of the stator housing 5 and the fitting tongue area of the stator blade 13 form a tongue-and-groove connection, which assumes exclusively the task of a means securing against rotation. As an alternative, the means securing against rotation may also comprise, as is shown in FIG. 12, two parallel position-securing grooves 24′ in the stator housing 5 and correspondingly two fitting tongues in the stator blade 13.
In the area of its lateral surfaces that project from the stator housing 5, the stator blade 13 is of a wedge-shaped design over its entire axial length. A spacer shell 25 each, whose lateral surfaces likewise extend in a wedge-shaped pattern, is inserted between the two stator blades 13 inserted into the stator housing 5 on one side and on the other side in such a way that they are secured against rotation. The wedge angles of the lateral surfaces of the stator blades 13 and of the lateral surfaces of the spacer shell 25 are equal and are selected to be such that a clamping and self-locking frictional engagement is formed due to the spacer shells 25 being pushed in, in the axial direction.
Such a stator 1 is manufactured as follows.
A commercially available drawn and internally honed tube is used as the starting product for manufacturing the stator housing 5 in the first three embodiments according to FIGS. 1 through 10. The inner circumferential surface of this tube has a surface finish of Rz=2, maximum, because of its prior machining and is therefore very well suited for use as a sealing surface. Therefore, no subsequent fine machining is needed. The tube is turned off to the corresponding lengths of the stator housing 5. The mounting slot 17 for the first embodiment, the wedge-shaped grooves 20, 20′ for the second embodiment or the fitting groove 21 and the fastening holes for the third embodiment are then prepared in the stator housing 5 according to a conventional machining operation.
The stator blades 13 are manufactured for this in the conventional manner with the corresponding dimensions and shapes and inserted into the stator housing 5.
The stator housing 5 and the stator blade 13 are then welded together by a low-warpage welding process in the first embodiment, pressed together in the second embodiment or secured in their positions relative to one another and screwed together in the third embodiment. The two front sides of the completed stator 1 are finally levelled off in the conventional manner and the intended holes in the covers and sealing grooves are prepared.
A commercially available tube, which does not have to meet any special requirements on the surface finish of the inner circumferential surface, is used as the starting product for manufacturing the stator housing 5 in the fourth embodiments according to FIGS. 11 and 12. The position-securing grooves 24 according to FIG. 11 or the position-securing groves 24′ according to FIG. 12 are then prepared in the stator housing 5.
The stator blades 13 are manufactured for this in the conventional manner with the dimensions and shapes adapted to the position-securing grooves 24, 24′ and inserted into the stator housing 5. At the same time, the spacer shells 25 are manufactured in the conventional manner with such dimensions and in such a shape that they fit between the two stator blades 13 when an axially acting pressing force is applied and are in contact over their full area with the inner circumferential surface of the stator housing 5. The inner surface of each spacer shell 25 is machined according to a conventional superfinishing process to a surface finish of Rz=1 to 2.
After finishing the individual parts, the stator blades 13 are pushed into the position-securing grooves 24, 24′ and then pressed against each other by means of the spacer shells 25 until self-locking occurs.
The two front sides of the completed stator 1 are finally leveled off in the conventional manner and the intended holes in the covers and sealing grooves are prepared.
While specific embodiments of the invention have been shown and described in detail to illustrate the application of the principles of the invention, it will be understood that the invention may be embodied otherwise without departing from such principles.

Claims

1. A radial swivel motor, comprising:

a stator with at least one, radially inwardly directed stator blade;

a rotor mounted in said stator with rotor blades, which form between said rotor and said stator at least one hydraulic, variable-volume pressure chamber and just as many hydraulic, variable-volume drain chambers;

frame sealing elements in said stator blades and in said rotor blades, wherein said pressure chambers and said drain chambers are sealed hydraulically against each other by said frame sealing elements in said stator blades and said rotor blades, said stator having a multi-part design comprising a stator housing and said stator blade, said stator blade being inserted into said stator housing in such a way that said stator housing and said stator blade rotate in unison.

2. A radial swivel motor in accordance with claim 1, wherein said stator housing has for each said stator blade a longitudinally extending mounting slot and each said stator blade has a mounting tongue fitting said mounting slot and said stator housing and said mounting tongue of said stator blade are connected to one another by a weld seam prepared on the outer circumference of said stator housing.

3. A radial swivel motor in accordance with claim 2, wherein to form a groove for said weld seam, said mounting slot of said stator housing and said mounting tongue in said stator blade have circular conical surfaces.

4. A radial swivel motor in accordance with claim 1, wherein said stator housing, for each said stator blade, has at least one longitudinally extending wedge-shaped groove and each said stator blade has an outer shape fitting said wedge-shaped groove, said wedge-shaped groove and the outer shape of said stator blade having such external dimensions that clamping and self-locking pressing are achieved and have a cross section with a dovetail profile.

5. A radial swivel motor in accordance with claim 1, wherein for mutual bracing, said stator housing and each said stator blade have fastening holes, said stator housing is provided with a fitting groove and each said stator blade is provided with a fitting tongue to mutually secure the positions, and each said stator blade carries at least one said sealing element extending over its entire length to guarantee sealing between said pressure chamber and said drain chamber.

6. A radial swivel motor in accordance with claim 1, wherein for securing against rotation, said stator housing has at least one position-securing groove extending over the entire axial length for each said stator blade and said stator blade is designed in its outer area as a fitting tongue, while each said stator blade has a wedge-shaped design over an entire axial length thereof in the area of lateral surfaces thereof for clamping and self-locking frictional engagement, and a spacer shell having lateral surfaces extending in a wedge-shaped pattern on one side and on the other side between two said stator blades.

7. A process for manufacturing a radial swivel motor, the process comprising:

providing a rotor;

providing stator covers;

providing individual stator blades;

providing sealing elements;

cutting a commercially available tube bar material to a length with an inner circumferential surface suitable for use as a sealing surface to manufacture a stator housing, the inner contour of said inner circumferential surface being prepared and front surfaces being finally leveled off and provided with recesses for said sealing elements and with holes for fastening said stator covers, wherein said stator is assembled nondetachably from said stator housing and said individual stator blades, wherein each said stator blade is manufactured with a finished contour providing longitudinally extending joining means fitting said stator housing.

8. A process in accordance with claim 7, wherein said stator housing receives said mounting slots and each said stator blade receives mounting tongues, which are welded together in the assembled state on the outer surface of said stator housing.

9. A process in accordance with claim 7, wherein said stator housing receives said wedge-shaped grooves and each said stator blade receives has a wedge-shaped outer shape, which are pressed together with said stator housing into a respective one of said grooves in the assembled state on the outer surface of said stator housing.

10. A process in accordance with claim 7, wherein said stator housing receives said fastening holes and said fitting grooves and each said stator blade receives fastening holes and a fitting tongue, which are screwed together in the fitted state on the outer surface of said stator housing.

11. A process in accordance with claim 7, wherein a commercially available tube without special requirements on the surface finish of the inner circumferential surface is used to manufacture said stator housing, said stator housing has said position-securing grooves and each said stator blade receives an outer shape coordinated with said position-securing grooves as well as lateral wedge surfaces, and a spacer shell with lateral wedge surfaces is inserted between two said stator blades, said stator blades and said spacer shells being pressed together on their wedge surfaces in a self-locking manner.