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 
       [0001]    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 
       [0002]    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 
       [0003]    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. 
         [0004]    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. 
         [0005]    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. 
         [0006]    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. 
         [0007]    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. 
         [0008]    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. 
         [0009]    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 
       [0010]    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. 
         [0011]    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. 
         [0012]    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. 
         [0013]    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. 
         [0014]    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. 
         [0015]    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. 
         [0016]    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. 
         [0017]    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. 
         [0018]    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. 
         [0019]    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. 
         [0020]    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. 
         [0021]    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. 
         [0022]    The novel swivel motor and the novel manufacturing process eliminate the drawbacks of the state of the art. 
         [0023]    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  
         [0024]    In the drawings: 
           [0025]      FIG. 1  is a longitudinal sectional view of a radial swivel motor; 
           [0026]      FIG. 2  is a cross sectional view of a first embodiment of the swivel motor; 
           [0027]      FIG. 3  is a perspective view of the stator housing according to  FIG. 2 ; 
           [0028]      FIG. 4  is a perspective view of a stator blade according to  FIG. 2 ; 
           [0029]      FIG. 5  is a cross sectional view of a second embodiment of the swivel motor; 
           [0030]      FIG. 6  is a perspective view of a form of the stator housing according to  FIG. 5 ; 
           [0031]      FIG. 7  is a perspective view of another form of the stator housing according to  FIG. 5 ; 
           [0032]      FIG. 8  is a perspective view of a stator blade according to  FIG. 5 ; 
           [0033]      FIG. 9  is a perspective view of the stator housing according to a third embodiment of the swivel motor; 
           [0034]      FIG. 10  is a perspective view of a stator blade of the third embodiment; 
           [0035]      FIG. 11  is a cross-sectional view of a fourth embodiment of the swivel motor; and 
           [0036]      FIG. 12  is a perspective view of the stator according to  FIG. 11 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0037]    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. 
         [0038]    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 . 
         [0039]    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 . 
         [0040]    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 . 
         [0041]    The stator housing  5  and the two stator blades  13  have a two-part design in a special manner. 
         [0042]    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. 
         [0043]    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 . 
         [0044]    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. 
         [0045]    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 . 
         [0046]    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 . 
         [0047]    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. 
         [0048]    Such a stator  1  is manufactured as follows. 
         [0049]    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. 
         [0050]    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 . 
         [0051]    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. 
         [0052]    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 . 
         [0053]    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. 
         [0054]    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. 
         [0055]    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. 
         [0056]    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.