Abstract:
A clamping device includes a base body defining at least a portion of at least one pressure chamber, which has at least one opening oriented in a direction of action. A membrane is connected with the base body in a pressure-tight manner and seals the at least one opening in the direction of action. The membrane defines a first side wall section of the pressure chamber. A movable second side wall section partially delimits the pressure chamber and a constant amount of pressure fluid is sealed in the pressure chamber. At least one mechanical actuator displaces or deforms the second side wall section in order to cause the membrane to outwardly bulge.

Description:
CROSS-REFERENCE 
     This application is the U.S. National Stage of International Application No. PCT/EP2011/064055 filed on Aug. 16, 2011, which claims priority to German patent application no. 10 2010 040 784.4 filed on Sep. 15, 2010. 
     TECHNICAL FIELD 
     The invention relates to a clamping device which has a base body having a pressure chamber. 
     BACKGROUND ART 
     DE 29 15 088 AI describes a bearing element having a cylindrical part and having a ring-shaped part surrounding it, on which a hydraulic pressure medium continuously acts, wherein a pressure element abuts on the ring-shaped part, which has a hollow space to which the hydraulic pressure medium is applied. The pressure element is a steel ring whose hollow space has a rectangular cross section. 
     SUMMARY OF THE INVENTION 
     In one aspect of the present teachings, a clamping device includes a base body, which has at least one pressure chamber having at least one opening oriented in the direction of action, and a membrane sealing the at least one opening, which membrane is connected with the base body in a pressure-tight manner, wherein a constant amount of fluid is enclosed in the pressure chamber, the membrane forms a first side wall section of the pressure chamber and the clamping device includes a device for moving a second side wall section of the pressure chamber on the clamping device. 
     The clamping device can thereby serve to fix at least one machine element, in particular a rolling-element bearing or at least one of its two bearing rings on a shaft or in a bearing bore by axially pressing against a seat or against a further machine element, or additionally to secure a different type of fixing, such as for example a press-fit. The clamping device can also thereby serve to be inserted between two mutually-opposingly disposed machine elements, in particular rolling-element bearings, such as for example two rolling-element bearings to be used, in order to clamp these two components. Using the clamping device, a plurality of machine elements, in particular a plurality of rolling-element bearings or at least one of each of their bearing rings, can be fixed and/or secured on a shaft or a bearing bore. 
     The clamping device can function according to the basic principle of a pressurized-fluid power cylinder, wherein the inventive base body forms the housing having a pressure chamber, in which a pressure fluid is confined, and wherein the inventive membrane is equivalent to the piston, which carries out a movement due to the fluid pressure in the pressure chamber formed by the base body. Here “direction of action” means, in the sense of the invention, the particular direction in which the membrane can carry out a movement, in order to transmit a force to the machine element or rolling-element bearing or rolling-element bearing ring to be clamped. In a variant, the inventive membrane can be formed by an end side of a threaded section of one or more screws, which penetrate into the pressure chamber. 
     The membrane can be designed differently depending on the design of the base body. Any thin-walled component can be understood as a “membrane” in the sense of the invention, which component is pressure-tight with regard to the pressure fluid used, and has an elasticity which permits a movement of the membrane, despite a pressure-tight connection with the base body, which pressure-tight connection seals the inventive opening. This elasticity can be achieved through the choice of the wall thickness, through the design of sections of the membrane, through the material properties of the membrane, or through a combination of at least two of these characteristics. The membrane can be manufactured from the same material as the base body, and it can be fastened to the base body at its component edges in a pressure-tight manner, and the movement for transmitting the clamping force can be effected through an elastic bulging-out of a central zone of the membrane. The base body can be manufactured from steel, in particular it can be manufactured from another material, as it is used for example in known bearing rings of rolling-element bearings. The membrane can be manufactured from a metal plate. 
     According to the invention, by connecting a membrane in a pressure-tight manner with the base body having the pressure chamber, the function of the clamping device is improved. Thus, for example, the membrane can be manufactured from a different material than the base body. To achieve the required elastic properties, the membrane can have a lesser hardness than the base body. Alternatively, the membrane can have a greater hardness than the base body, and can be formed very thin to achieve the required elastic properties. Also, due to the use of at least one inventive membrane, only selected zones, instead of an entire surface, can also be formed in an elastically movable manner, in order to transmit a clamping force. In addition to the functional improvement, the base body can be manufactured more simply and thereby more cheaply, since no undercut hollow chambers must be manufactured, but rather the pressure chamber can be formed in the base body as open on one side, and this opening is subsequently closed by the inventive metallic membrane, in order to form a pressure-tight pressure chamber. 
     In the inventive clamping device, the pressure in the pressure chamber can be changed through individualized adjustment of the second side wall section of the pressure chamber. This is possible because a constant amount of fluid is enclosed in the pressure chamber. 
     By moving the second side wall section, and due to the constant amount of pressure fluid, the first side wall section or the membrane bulges outward. Using the bulging-out membrane, a machine element such as a rolling-element bearing can be mechanically clamped in a defined manner. The inventive clamping device can be controlled, i.e. its function monitored and optionally also adjusted. The clamping device can be repeatedly reused. The clamping device can be utilized universally, i.e. versatilely; in particular it can be used with different machine elements or rolling-element bearings without complex structural adaptations of the clamping device. 
     The device for moving the second side wall section can have a mechanical actuator. The mechanical actuator can either directly penetrate into the pressure chamber, or move the second side wall section, or indirectly act on the second side wall section of the pressure chamber. In one embodiment, in which the mechanical actuator acts directly on the pressure chamber, the mechanical actuator or a mechanical part of the actuator can penetrate into the pressure chamber. For this purpose the mechanical actuator can for example have a plunger or plunger section that penetrates into the pressure chamber. 
     In one embodiment, in which the mechanical actuator acts indirectly on the side wall of the pressure chamber, the mechanical actuator can move at least one side wall. Alternatively the mechanical actuator can deform at least one side wall. Consequently the mechanical actuator can be formed to move and/or deform a second side wall section of the pressure chamber. 
     Alternatively, the side wall or the second side wall section of the pressure chamber can be moved or deformed by a plunger or plunger section. 
     In one embodiment, the mechanical actuator can include a set screw for actuating the plunger section. For example, the plunger section can be formed from a threaded section of a set screw. 
     In all inventive embodiments, the second side wall section can be disposed, delimiting the pressure chamber, opposite of the membrane or opposite of the first side wall section. The second side wall section can in particular be disposed extending parallel to the membrane or the first side wall section. 
     In one embodiment, at least one set screw is axially-adjustably held using an externally-threaded section in an internally-threaded bore of the base body. The set screw can for example be actuated, i.e. turned, at a screw head. An end side of the screw opposite the screw head presses on a side wall section of the pressure chamber in the axial direction. This second side wall section can be flexed or bulged by the end side due to the advance of the screw. The membrane, i.e. the first side wall section of the clamping device, thereby bulges outward in turn. Both the membrane or the first side wall section and the second side wall section, which is actuated, i.e. deformed, by the screw, can be welded with the base body, in order to form a pressure-fluid-tight pressure chamber. 
     A constant amount of pressure fluid is enclosed in the pressure chamber of the inventive clamping device. In all inventive designs, the clamping device can be provided with a fill opening for filling an empty pressure chamber. The fill opening for pressure fluid can be disposed on a circumferential side of the base body. In all designs, the fill opening can be sealed by a stopper. Thus a constant amount of pressure fluid remains enclosed in the pressure chamber of the clamping device. 
     In all inventive designs the base body can be a metallic base body. 
     In all inventive designs the membrane or the first side wall section and/or the second side wall section can be connected with the base body in a pressure-tight manner, in particular welded or adhered. 
     The base body can be formed as a substantially ring-shaped body or as a ring, which is provided with a groove at least partially encircling the body for forming the at least one pressure chamber on its end surface oriented towards the direction of action; the groove is sealed by a substantially ring-disk-shaped membrane matched to the encircling extension of the groove. The thickness of the membrane and the depth of the groove can be dimensioned such that the outer side of the membrane terminates flush with the end side of the base body. In a groove for forming a receiving space for the membrane, a second groove can be provided in the groove base of a first groove, which second groove defines the size of the pressure chamber. This means that the groove can be designed in a stepped manner, so that it has a shoulder, on which the membrane sits in its installed position. 
     Alternatively, the base body can have a narrow groove on its end side oriented in the direction of action, which forms a closed section, which corresponds to the shape of the outer boundary of the membrane. An edge of the membrane extending opposite of the direction of action can engage in this groove. 
     In all inventive designs, the base body can be provided with a thread, in particular with an external thread disposed on the outer circumferential side of the base body, and/or with an internal thread disposed on the inner circumferential side of the base body, for forming a clamping nut. An inventive clamping device formed as a clamping nut can be used for the clamping of rolling-element bearings. Using a clamping nut having a thread, a single bearing ring of a rolling-element bearing, or a plurality of bearing rings of a plurality of rolling-element bearings can be clamped against a bearing seat or against a further rolling-element bearing. 
     The base body can be a metallic base body. Alternatively or additionally, the membrane or the first side wall section and/or the second side wall section can be a metallic membrane. The membrane or the first side wall section and/or the second side wall section can be manufactured as a composite component, in particular as a composite component having metallic components. 
     A membrane which is for example metallic or the first side wall section and/or the second side wall section can be connected with the base body in a pressure-tight manner, in particular welded or adhered. An edge side of the in particular metallic membrane or the first side wall section and/or the second side wall section can thereby abut on the base body. The in particular metallic membrane or the first side wall section and/or the second side wall section can form a butt joint or flat joint with the base body, which is welded, preferably flush, using a weld seam encircling the edge of the in particular metallic membrane or the first side wall section and/or the second side wall section, in particular a butt weld or a V-weld. 
     In particular the inventive clamping device or the inventive clamping nut can serve to clamp rolling-element bearings for the rotor support of wind turbines, in particular of the multi-megawatt class. Large rolling-element bearings of this type can be clamped based on a double row tapered roller bearing, for example an outer diameter of 2330 millimeters. These double row tapered roller bearings can also support tilting moments in addition to the usual radial and axial loads. It is thereby possible to support the rotor with only a single bearing. 
     In all inventive designs, a plurality of devices for moving the second side wall section of the pressure chamber, in particular a plurality of mechanical actuators, can be disposed in a distributed manner, in particular in an evenly distributed manner, around the circumference of the base body. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       An exemplary embodiment of the invention is illustrated in an exemplarily manner in the appended schematic drawings: 
         FIG. 1  shows a plan view of an inventive clamping device, 
         FIG. 2  shows a cross section along the intersecting line A-A through the inventive clamping device according to  FIG. 1 , 
         FIG. 3  shows an enlarged partial cross section B from the view according to  FIG. 2 , in an unclamped position; 
         FIG. 4  shows an enlarged partial cross section B from the view according to  FIG. 2 , in a clamped position; 
         FIG. 5  shows a partial cross section through an assembly group including a bearing seat, a rolling-element bearing, and the inventive clamping device according to  FIGS. 1 to 4  in a clamped installation situation. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The clamping device illustrated in  FIG. 1  has a circular-ring-shaped base body  3 . A plurality, i.e. in the depicted exemplary embodiment twenty-four, mechanical actuators  9  are disposed in an evenly distributed manner on a circle on a rearward end side  5  of the base body  3 ; the rearward end side  5  is depicted so as to be visible in the forward direction in  FIG. 1 . 
     In  FIG. 2  the clamping device  1  according to  FIG. 1  is illustrated in a cross section along the intersecting line A-A. The clamping device  1  includes a membrane  21  on a front-side end surface  15  of the base body  3  opposite the rearward end side  5  of the base body  3 . 
     The arrangement of the membrane  21  on the clamping device  1 , in particular on the base body  3 , is shown in an enlarged and exposed manner in  FIG. 3  in a detail view. An inventive clamping device is illustrated in  FIG. 3  in an unclamped, i.e. for example unpressurized, position. 
     The base body  3  of the clamping device  1  has a pressure chamber  13 . To form the pressure chamber  13 , the base body  3  is formed as a ring  3   a  that is provided with an encircling groove  17  on its end surface  15  oriented in the direction of action, i.e. on the front-side end surface  15 . The groove  17  has a shoulder  19 , on which the in particular ring-disk-shaped membrane  21  sits. The ring-disk-shaped membrane  21  seals the groove  17  while maintaining the pressure chamber  13 . The groove  17  has in this respect an opening  23  towards the front-side end surface  15 , i.e. in the direction of action; the opening  23  is sealed in a pressure-tight manner by the membrane  21  while forming of the pressure chamber  13 . The membrane  21  is connected with the base body  3  in a pressure-tight manner. The base body  3  and the membrane  21  are preferably manufactured from metallic materials, they are especially preferably manufactured from steel. In the illustrated exemplary embodiment, the membrane  21  is welded with the base body  3  in a pressure-tight manner by using an encircling welding seam  25 . 
     A second membrane  27  is connected with the base body  3  in a pressure-tight manner in the region of a groove base  19 , for example welded by an encircling welding seam  35 . A pressure fluid  29  is enclosed between the membrane  21  or the first side wall section  31  and the membrane  27  or the second side wall section  37 . The pressure fluid  29  can be filled into the pressure chamber  13  via a fill opening  11 . The pressure fluid  29  can be held in a sealed manner in the pressure chamber  13  using a stopper  33 . 
     The inventive clamping device according to  FIG. 3  is illustrated in  FIG. 4  in a position clamping the rolling-element bearing  45 . 
     The mechanical actuator  9  includes the set screw  9   a . The depicted set screw  9   a  represents one of a plurality of mechanical actuators  9 , which are shown in  FIG. 1 . The set screw  9   a  is axially-adjustably screwed into the ring-shaped base body  3 , i.e. into the ring  3   a , using a threaded section, which forms the plunger section  7 . When the set screw  9   a  is screwed in, then an end side of the set screw  9   a  presses in the region of the plunger section  7  against a back side of the second membrane  27  in such a way that the second membrane  27  bulges inward, i.e. towards the pressure chamber  13 , i.e. into the fluid  29 . The periphery-side of the second membrane  27  is connected with the base body  3 , i.e. with the ring  3   a , in a pressure-tight manner by the welding seam. In the unclamped state, the second membrane  27 , as shown in  FIG. 3 , lies flat or flush on the groove base  19  of the groove  17 . Since a constant amount of pressure fluid  29 , which can for example be glycerin, is enclosed in the pressure chamber  13 , the first membrane  21  or the first side wall section  31  of the pressure chamber  13  bulges outward and presses the rolling-element bearing  45  or, in the illustrated exemplary embodiment, an inner ring of the rolling-element bearing  45  against a bearing seat  44 , as shown in  FIG. 5 . With regard to the production of an inventive clamping device  1 , in particular a bearing clamping device, the groove  17  can first be lathed into the base body  3 ; subsequently the second membrane  27  can be welded first, and then the first membrane  21  can be welded. Subsequently the pressure fluid  29  is filled into the pressure chamber  13  via the fill opening  11 , and the pressure chamber  13  is sealed using the stopper  33 . The stopper  33  can for example be welded in, adhered, or pressed in. 
     In the embodiment shown in  FIGS. 3 and 4 , the base body  3  is provided with a thread  43  to form a clamping nut  1   a . In the depicted exemplary embodiment, the thread  43  is disposed on the inner circumferential side of the base body  3  and thus represents an internal thread  41 . 
     Thus the invention can relate to the securing of a rolling-element bearing using a clamping nut  1   a . For this purpose a preferably one-piece base body  3  can have an encircling pressure chamber  13  on its end surface  15 , which abuts on a bearing inner ring. In the exemplary embodiment, the pressure chamber  13  is sealed using a welded-on membrane  21 . After turning the clamping nut  1   a  until the membrane  21  fully abuts on the bearing ring of the rolling-element bearing, the pressure in the pressure chamber  13  is increased by tightening the set screw  9   a . The first membrane  21  bulges forward and clamps the two inner rings  47   a ,  47   b  of the rolling-element bearing  45  against the bearing seat  44 . In all such embodiments, the clamping device  1  forms a bearing clamping device. 
     The relatively thin sidewall of the membrane  21 , which is welded onto the base body  3 , bulges elastically outward and thus axially loads the rolling-element bearing with the required axial preload. 
       FIG. 5  shows a partial cross section through an assembly group including a bearing seat  44 , a rolling-element bearing  45  and the inventive clamping device  1  or the clamping nut  1   a . The clamping nut  1   a  mutually clamps the two inner rings  47   a ,  47   b  of an exemplarily illustrated double row tapered roller bearing  45   a  in a preloaded position and together against the bearing seat  44 . 
     In the depicted exemplary embodiment, both bearing rows of the double row tapered roller bearing  45   a  have a contact angle of 45°. This imparts to the rolling element bearing  45   a  a large supporting width and thus high stiffness. A further advantage of the large contact angle is the small cone angle of the rollers  49  resulting therefrom. The smaller the cone angle, the lower the friction is between the rollers  49  and the guide flange  51 . Additionally the guide flange  51  is designed in a tribologically advantageous manner, so that an ideal lubricating film can adapt to the roller-flange contact. 
     Based on the values which are given for such double row tapered roller bearings  45   a , upon the occurrence of a, e.g., maximal axial operating load of F axmax =7,500 kN, a pressure of approximately 350 bar would be present in the pressure chamber  13 . Due to the welding seams  25  in the front-side end surface  15 , and since the complete front-side end surface  15  can abut flat on the components to be clamped, such as for example the inner ring  47   b  according to  FIG. 5 , a tearing-open of the welding seams can be prevented. 
     For filling the pressure chamber, for example one of the fill openings  11  illustrated in  FIG. 2  can be used for venting, while the pressure fluid can be filled via the other fill opening  11 . Further, the pressure chambers  13  can be evacuated using a suitable device prior to the filling with the pressure fluid, so that for example no air can remain in the pressure chambers  13 . 
     REFERENCE NUMBER LIST 
     
         
           1  Clamping device 
           1   a  Clamping nut 
           3  Base body 
           3   a  Ring 
           5  Rearward end side 
           7  Plunger section 
           9  Mechanical actuator 
           9   a  Set screw 
           11  Fill opening 
           13  Pressure chamber 
           15  Front-side end face 
           17  Groove 
           19  Groove base 
           21  First membrane 
           23  Opening 
           25  Welding seam 
           27  Second membrane 
           29  Pressure fluid 
           31  First side wall section 
           33  Stopper 
           35  Welding seam 
           37  Second side wall section 
           41  Internal thread 
           43  Thread 
           44  Bearing seat 
           45  Rolling-element bearing 
           45   a  Double row tapered roller bearing 
           47   a ,  47   b  Inner rings 
           49  Rollers 
           51  Guide flange