Patent Publication Number: US-2007107998-A1

Title: Coupling/brake combination

Description:
The present invention is based on a state of the art as established by applicant&#39;s DE 201 05 746.8 or WO 02/084 841.  
      In the prior-art design, an elastically flexible coupling such as a bellows-type coupling or a plug-in coupling including a resilient star coupling member is provided between the motor shaft and the transmission input shaft, or the spindle, to be driven and the assembly then shielded from the environment by a connector element constituting a so-called “lantern”—see  FIG. 1 .  
      In the prior-art design it is assumed that the brake is mounted on a servo motor acting on the power input side of the brake. The second shaft—to be connected through the bellows coupling—may be part of a transmission, a spindle, a ball screw or the like. A drawback of this construction is its relatively great length. Also, if the coupling/brake combination is to be mounted in a vertical position, a number of additional problems have to be considered.  
      For example, if the coupling is broken by external influence, the suspended machine elements below it may “crash”, potentially causing considerable damage.  
      The same problem of suspended machine elements crashing arises if the drive motor is defective and has to be removed for repair or replacement.  
      Besides, it is desirable in many specific mounting situations to have available a coupling/brake combination featuring a particularly short structural axial length.  
      It is the object of the present invention to eliminate the aforesaid problems in a manner as efficient as possible.  
      In accordance with the present invention, this object is achieved by designing the coil carrier housing of the brake including the magnetic coil to correspond approximately to the external dimensions of the aforesaid “lantern”. To this end, the brake rotor including its friction liners and its teeth (or splines) are mounted directly on the hub connected with the bellows coupling and its clamps or with any other flexible coupling present. What this means is that the brake is mounted on the power output side so as to continue to perform its braking function for downstream machine components also in case the coupling fails or the drive motor has to be removed for repair or the like.  
      The inventive solution results in the following advantages: 
          1. After the brake has been mounted directly on the transmission or spindle shaft by its peripheral teeth or splines, no further parts of the coupling exist between the motor and the transmission which would cause the brake to become ineffective if the coupling broke.     2. Should the motor have to be replaced, this is easily done as the brake is mounted directly on the power output side so that the braking effect is maintained. As a result, it is possible to withdraw the motor shaft from the coupling; the braking effect will still be present.     3. By configuring the coupling/brake combination in the way of the aforesaid “lantern”, the end faces of the two shafts (motor shaft, transmission or spindle shaft) can be arranged in their closest proximity possible so as not to waste any construction space.     4. The conventional “lantern” with the bellows coupling therein or a star-type plug-in coupling therein is not needed any longer; inserted instead is a complete brake with its corresponding housing and having its center configured to receive and accommodate a flexible coupling such as a bellows coupling or a star-type plug-in coupling. This results in optimum use of the available space and in a simple and compact design.       

    
    
      The present invention is explained in greater detail now under reference to the attached drawings.  
       FIG. 1  schematically shows a typical prior-art mounting situation involving a “lantern” (=connector sleeve  3 ) in a vertical drive train, e.g. between a drive motor  2  and a transmission or gear box  1 ; the present invention substantially improves this mounting situation, with drive motor  2  connected to transmission/gear box  1  via a coupling such as a bellows coupling or a star-type plug-in coupling (see  FIGS. 7 and 8 );  
       FIG. 2  completely shows a first embodiment of the invention (section along line A-A in  FIG. 4 );  
       FIG. 3  shows a sectional view similar to  FIG. 2 , but along line B-B in  FIG. 4 ;  
       FIG. 4  shows a right-hand view of  FIGS. 2 and 3 ;  
       FIG. 5  shows another preferred configuration of the first embodiment of the inventive coupling/brake combination;  
       FIG. 6  shows an alternative embodiment of the inventive coupling/brake combination without a flexible coupling but with an additional shaft and the same connecting dimensions as the attached motor (shaft and centering elements with partial attachment circle);  
       FIG. 7  shows another embodiment of the inventive coupling/brake combination similar to  FIGS. 2 and 3 , but including a star-type plug-in coupling with a junction box as well as a brake release monitor;  
       FIG. 8  is an exploded version of  FIG. 7  to better show the flexible coupling in the form of a star-type plug-in coupling;  
       FIG. 9  shows another embodiment of the inventive coupling/brake combination including an integral overload clutch connected to the flexible plug-in coupling;  
       FIG. 10  shows yet another embodiment similar to  FIG. 6 , including two brakes serially connected to obtain a redundant (dual-circuit) brake system; and  
       FIG. 11  shows an exemplary application, i.e. the coupling/brake combination attached to a housing with a spindle and a build-on motor. 
    
    
       FIG. 2  shows a preferred embodiment example of the inventive coupling/brake combination, with the essential aspect thereof to be seen in that a static current activated friction brake (=braking action by way of springs in the absence of current) is integrated in the “lantern” (i.e. connector sleeve  3  in  FIG. 1 ), with the brake having its rotor  8  mounted inside the lantern on teeth or splines  13  on central hub  15  of hollow shaft section  16  on the power output side and with the hollow shaft section adapted to be connected with the output shaft by means of a clamp ring  14  to be tightened by a clamp screw  33 .  
      Towards the power input side, hollow power output shaft section  16  has an axial extension in the form of an elastically flexible coupling—in this case a bellows coupling  18  welded in place and having at its power-input end a clamp ring  12 , the latter adapted to be tightened by means of a clamp screw  32 .  
       FIG. 2  shows hollow power output shaft section  16  and bellows coupling  18  completely surrounded by an external housing which corresponds to connector sleeve  3  or to the “lantern” in  FIG. 1 ; at the same time, this housing is designed to act as a coil carrier  5  housing magnetic coil or solenoid  6 , which cooperates in a well-known manner with axially movable but non-rotating armature disc  7  to attract the latter in the magnetically energized condition against the force exerted by compression springs  19 . In the non-energized condition of the coil, compression springs  19  urge armature disc  7  against brake rotor  8  which has friction liners  9  on both sides thereof and is coupled through teeth or splines  13  with hollow shaft  16  to be non-rotating but axially movable therealong. In the braked condition, friction liners  9  engage armature disc  7  as well as brake flange  10 , which takes the place of the “lantern”.  
      In  FIG. 2 , the right-hand termination is formed (instead of by the “lantern”) by a concentrically attached adjustment ring  23  including centering feature  25  for drive motor  2  (not shown in detail). The adjustment ring has a radial through-bore  22  which enables a tool (for releasing or tightening damp screw  32 ) to be introduced externally into the assembly. By being adjustable circumferentially, ring  23  ensures constant access to clamp screw  32  regardless of the random rest position of clamp ring  12  when the unit is at standstill.  
       FIG. 3  shows the apparatus attached in place by means of externally threaded fasteners via spacer sleeves  27  having bores  30  therethrough, said fasteners extending into internally threaded bores  28  in coil carrier  5 . Adjustment ring  23  is somewhat shorter than spacer sleeves  27  so that, in the attached condition, adjustment ring  23  can be rotated to bring throughbore  22  in adjustment ring  23  into any position needed to gain access to clamp screw  32  on the motor side of clamp ring  12 .  
       FIG. 4  shows (in a dashed side view) throughbore  22  in adjustment ring  23 , through which clamp screw  23  can be accessed.  
       FIG. 5  shows three or more externally threaded pins  38  equidistantly distributed around the periphery of adjustment ring  23  to ensure that the bellows will not be crushed or damaged in case motor shaft  17  is introduced in a skewed manner in bellows coupling  18 . Once pins  38  extend into annular groove  39  in bellows coupling  18 , the bellows can never be compressed or excessively stretched when shaft  17  is pushed in or withdrawn. Gap  40  between coil carrier housing  5  and bellows coupling  18  additionally serves to radially limit radial deflections in order to prevent unnecessary excessive radial offsets, which would be likely to permanently damage the coupling. Also, this produces another advantage for transportation of the entire coupling/brake combination.  
      Hub  15  in  FIG. 2  can be designed to have not a hollow shaft section  16  but a solid stub-type shaft section  34 , as shown in  FIG. 6 . Another possibility is to altogether omit the bellows coupling shown in  FIG. 2  and to directly introduce motor shaft  17  (shown in phantom in  FIG. 5 ) into the bore of a hollow shaft section  36  and to clamp it in place by means of a clamp ring  37 . In this case, brake flange  10  should conveniently incorporate a ball bearing assembly  35 . This ball bearing assembly  35  should be a totally encapsulated variety; alternatively, brake flange  10  could be designed to be broader and to have a seal mounted therein to keep any oil or the like away from brake liners  9 .  
       FIG. 7  shows an alternative form of the inventive assembly including plug-in coupling  41  with a resilient star-type coupling member  42 . Clamping is accomplished by means of a clamp screw  32  also. On its power output side  2 , the clamping of hub  15  is effected by means of a tensioning ring  43  tightened by tensioning screws  44 . A sealing flange  45  has therein an annular seal  46  to protect friction liners  9  against dirt and oil.  
      Junction box  47  houses an brake release indicator  48  (microswitch) adapted to show the operating condition of the brake (disengaged or engaged).  
      For clarity,  FIG. 8  shows an exploded view of the embodiment of the invention including a plug-in coupling  41  incorporating a resilient star member  42 . Tensioning screws  44  are used for tightening tensioning ring  43  to connect the output shaft (transmission or gear box, spindle or the like) to the coupling.  
       FIG. 9  shows an embodiment in which plug-in coupling  41  is connected with an overload clutch  49  which disengages and moves axially in response to an overload condition. The axial movement is picked up by an initiator  50  to deenergize the drive motor, thus protecting the entire drive unit against overload.  
       FIG. 10  shows a brake system which is redundant in that a second set of magnetic coil  51 , armature disc  52  and rotor  53  is included to form a complete second brake.  
       FIG. 11  shows the attachment of drive motor  2  with its stub shaft and centering feature to the coupling/brake composition shaped like the “lantern”. The coupling/brake combination is then attached to a housing accommodating a spindle or a transmission. The prior art “lantern”  3  of  FIG. 1  is omitted and replaced by the inventive coupling/brake combination. An essential advantage of this design is that it enables existing machines to be retrofitted simply and without adaptation work by removing the conventional “lantern”  3  and coupling  4  and installing a coupling/brake combination, thus arriving at the same overall structure. The measure does not entail additional expense, yet it ensures extra safety by providing a spring-actuated brake.  
      Operation:  
      The brake uses the well-known static current principle (=braking action by way of springs in the absence of current). Magnetic coil  6  inside coil carrier housing  5  has a voltage applied thereto. This attracts armature disc  7  axially against the pressure exerted by compression springs  19 , with the torque transmitted by bolts  20 . Thus rotor  8  and its two friction liners  9  can follow the input rotation via the teeth or splines  13  on hub  15 , which can rotate freely. In the absence of the energizing current springs  19  urge the armature disc against friction liners  9 , so that hub  15  is braked to a standstill.  
      Drive:  
      Being introduced into bellows coupling  18  from the right in  FIG. 2 , motor shaft  17  is adapted to be clamped in position by clamp ring  12  and screw  32 . Torque is transmitted from motor shaft  17  to bellows coupling  18  (or star-type plug-in coupling  41 ) connected to hub  15 . Clamp ring  14  allows any stub shaft—as of a transmission or a spindle—to be introduced into hollow shaft section  16 . Preferably, hollow shaft section  16  has therein a stop  31  to prevent too great a length of the shaft from being introduced. Clamp ring  14  and screw  33  are then used to clamp and secure the output shaft (of a transmission or spindle) in place, so that torque can be transmitted from the input to the output of the combination as desired.  
      For installation, the first step is the clamping in place of the transmission shaft, which can be effected via throughbore  21  by means of an Allen-type wrench acting on screw  33 . The coupling/brake combination is attached to the transmission or a housing by engaging the centering feature and then securing it in place in four places through bore  29 . Connecting screw  11  serves merely to fix housing  5  on brake flange  10 .  
      Motor Attachment:  
      Motor shaft  17  is introduced in the bellows coupling and clamp ring  12  is clamped in place on the motor shaft by means of Allen screw  32  through bore  22 . With centering feature  25  engaged, the motor is fixed in place on adjustment ring  23  and secured by means of threaded bolts to threads  28  via four spacer sleeves  27  and the bores  30  therein.  
      Advantageous Further Developments:  
      Adjustment ring  23  is designed to be rotated into any position (in an event such as a motor failure) to align bore  22  with screw  32  of clamp ring  12  for releasing motor shaft  17  in any position and for withdrawing it axially from the coupling. This design results in a self-contained coupling/brake combination which allows the motor to be installed or removed in any rotary position thereof. This is important in the case of motor defects, which prevent the motor from operating and thus from being rotated to any specific disassembly position.  
      In the embodiment of  FIGS. 7 and 8 , the advantage of a plug-in coupling over a bellow coupling is that adjustable intermediate ring  23  can be omitted. In that case, the coupling/brake composition can be attached to the housing in its entirety, and it is then that the motor with the plug-in coupling  41  and the resilient star  42  are introduced in the coupling/brake combination and the motor is secured to the latter. Disassembly is possible in any rotary position of the motor as the coupling is pluggable and the motor can be withdrawn together with coupling  41  and star member  42 .  
     LIST OF REFERENCE CHARACTERS  
     
         
           1  Transmission/spindle or the like  
           2  Motor  
           3  Lantern between motor and the transmission  
           4  Coupling  
           5  Coil carrier housing  
           6  Magnetic coil  
           7  Armature disc  
           8  Rotor  
           9  Friction liners  
           10  Brake flange  
           11  Connecting screw  
           12  Clamp ring (motor-side)  
           13  Teeth or splines  
           14  Clamp ring (transmission-side)  
           15  Hub (with teeth or splines  15 )  
           16  Hollow shaft section (transmission-side)  
           17  Motor shaft  
           18  Bellows coupling  
           19  Springs (compression springs)  
           20  Bolts  
           21  Bore in the brake flange  
           22  Bore in the adjustment ring  
           23  Adjustment ring  
           24  Centering feature on coil carrier  5   
           25  Centering feature on the motor adjustment ring  
           26  Outer centering feature on the brake flange  
           27  Spacer sleeves  
           28  Threads in coil carrier  5   
           29  Throughbore in coil carrier  5   
           30  Throughbore in spacer sleeve  
           31  Stop inside hollow shaft section  16   
           32  Clamp screw (motor-side)  
           33  Clamp screw (transmission-side)  
           34  Stub shaft  
           35  Shaft bearing  
           36  Hollow shaft section for motor shaft  
           37  Clamp for motor shaft  
           38  Threaded pins in adjustment ring  23   
           39  Groove in clamp ring  12   
           40  Radial centering feature  
           41  Plug-in coupling  
           42  Resilient star  
           43  Tensioning ring (tapered)  
           44  Tensioning screws  
           45  Sealing flange  
           46  Annular seal  
           47  Junction box  
           48  Brake release indicator (microswitch)  
           49  Overload clutch  
           50  Initiator (sensor)  
           51  2nd magnetic coil  
           52  2nd armature disc  
           53  2nd rotor