Abstract:
Clutch handle apparatus for opening doors and the like includes a torque limiting clutch subassembly which selectively disengages the handle from a spindle to prevent damage. The clutch subassembly includes a slip clutch removably coupled to a spindle pin allowing corotation of the handle and the spindle below the application of a predetermined torque, and free rotation of the handle with respect to the spindle by uncoupling the pin and the slip clutch at and above the application of a predetermined of torque to the handle.

Description:
BACKGROUND OF THE INVENTION 
     The present invention is directed to apparatus for opening and closing doors, windows and the like such as a handle or lever for applying torque to door opening mechanisms. The handle includes a torque-limiting clutch subassembly which disengages the handle from the door opening mechanism at and above a predetermined torque. 
     Handles or levers for applying torque to door opening mechanisms to enable opening or closing a door are well known. However, excess torque can damage the handle, the door and/or the door opening mechanism, for example when excessive force is applied to the handle when the door opening mechanism is in a locked or secured position. Similarly, even when the door opening mechanism is unlocked, excess torque may damage the handle, the door and/or the door opening mechanism. 
     A variety of breakaway handle devices have attempted to solve these problems. For example, U.S. Pat. No. 1,910,125 includes a handle barrel which receives a longitudinally slidable sleeve. In operation, if excess torque is applied to the handle, the sleeve moves to a disengaged position where no torque is transmitted to the handle barrel. U.S. Pat. No. 2,273,632 shows a similar arrangement in which a moveable sleeve presses against and compresses a spring at a predetermined torque to disengage a tooth and notch connection between the handle and sleeve. Similarly, U.S. Pat. No. 3,314,708 includes a pair of opposed ball bearings which are normally biased into driving engagement with a sleeve by a spring-loaded plunger. Upon application of a predetermined torque, the ball bearings displace the plunger against the spring biasing force to disengage the balls from the sleeve. 
     These prior devices have attempted to solve the problem of preventing damage to handles, doors and door locks caused by excessive handle torque. However, a need exists for a simplified yet durable apparatus having the features of the present invention. 
     SUMMARY OF THE INVENTION 
     The present invention is based on a handle to transmit force through a spindle to a door opening mechanism. The handle is provided with a torque-limiting clutch subassembly to protect the handle against damage in the event that excess torque is applied to the handle, particularly, for example, when the door is locked. This object is inventively achieved in accordance with a slip clutch placed in working contact with the spindle within the handle. The slip clutch is provided with at least one notch to normally seat a spindle cross pin such that, upon application of a force, the handle normally rotates with the spindle through the coupling between the notch and the cross pin. However, upon the application of a predetermined force or torque, the cross pin will ride up out of the notch in the slip clutch thereby allowing the handle to rotate without rotating the spindle to prevent damage to the handle, the clutch subassembly, and/or the door opening mechanism. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention and further features and advantages thereof are explained in greater detail on the basis of the exemplary embodiments schematically shown in the figures. 
     FIG. 1 is a partial sectional view of the inventive clutch handle along the line A—A of FIG.  3  and showing a clutch subassembly thereof in an exploded side elevational view. 
     FIG. 2 is a partial sectional, partial elevational, side view of the clutch handle of FIG. 1 but showing the clutch subassembly in an operational configuration within the handle. 
     FIG. 3 is front elevational view of the clutch handle. 
     FIG. 4 a  is a perspective view of a slip clutch of the clutch handle. 
     FIG. 4 b  is a sectional elevational view of the slip clutch of FIG. 4 a  taken along line B—B thereof 
     FIG. 4 c  is a side elevational view of the slip clutch of FIG. 4 a.   
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     While the present invention may be embodied in many different forms, there is shown in the drawings and discussed herein one or more specific embodiments with the understanding that the present disclosure is to be considered only as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiments illustrated. 
     Referring to the drawings in more detail, FIG.  1  and FIG. 2 illustrate a rotatable handle  10  housing a torque-limiting clutch subassembly  12  which provides for the selective disengagement of the handle  10  from a door opening mechanism (not shown) at and above a predetermined torque according to an exemplary embodiment of the present invention. 
     Referring to FIG.  1  and FIG. 3, the handle  10  comprises a generally cylindrical cap  14  integrally formed with a depending lever arm  16 . A blind recess or bore  18  defining a cylindrical inner wall  20  and a circular bearing surface  22  is formed in the cap  14 . A plurality of longitudinal grooves  24  (two of which are illustrated in FIG. 1) are symmetrically spaced apart around the circumference of the inner wall  20  (see also FIG.  3 ). Referring to FIG. 1, a semispherical recess  26  is formed at the center of the bearing surface  22 . 
     Referring now to FIG.  1  and FIG. 2, the clutch subassembly  12  comprises a generally annular slip clutch  28 , a biasing helical spring  30 , a supportive bushing  32 , and a spindle  34  which transmits force, for example by linear displacement, to a door latch mechanism (not shown). 
     Referring to FIG. 4 a , FIG. 4 b  and FIG. 4 c , the slip clutch  28  includes a face  36 , a rear  38 , and an axial passage or bore  40 . As illustrated in FIG. 4 a  and FIG. 4 b , a pair of notches  42  spaced 180° apart around the outer circumference of the face  36  define respective pairs of opposed inclined surfaces or ramps  43 . Referring to FIGS. 4 a - 4   c , a plurality of semispherical recesses  44  are symmetrically spaced apart around an outer surface of the slip clutch  28 . Referring to FIG.  1  and FIG. 2, the recesses  44  are sized to supportively seat balls  45  which in turn are received by and communicate with the grooves  24  to facilitate back-and-forth longitudinal or axial movement of the slip clutch  28  within the bore  18 . As discussed more below, the grooves  24  also limit or preclude rotational movement of the slip clutch  28  with respect to the handle  10  (i.e., the slip clutch  28  rotates with the handle  10 ). 
     Referring to FIG.  1  and FIG. 2, the spindle  34  includes a cross pin  46  extending outward from or perpendicular to the spindle  34 , the function of which is discussed below, and a spindle end face  48 . 
     FIG. 2 illustrates the clutch subassembly  12  in its operational configuration within the cap  14 . As shown in FIG. 2, the spindle  34  extends into the bore  18  with a ball  50  provided between the spindle end face  48  and the recess  26  in the bearing surface  22  to facilitate rotation of the spindle  34  with respect to the handle  10 . 
     As illustrated in FIG. 2, the slip clutch  28 , the spring  30  and the bushing  32  slip over the spindle  34  in series in a coaxial alignment. More particularly, referring to FIG.  1  and FIG. 2, the slip clutch  28  is positioned adjacent the bearing surface  22  with each of the grooves  24  supportively receiving corresponding balls  45 . In this position, one of the notches  42  is seated against (i.e., firmly engages) the spindle cross pin  46 . The biasing spring  30  is fitted over the spindle to abut against the slip clutch rear face  38 , and the bushing  32  is threaded or fit into an open end of the cap  14  to engage and bias the spring  30  against the rear  38  of the slip clutch  28 . 
     Referring to FIG. 2, in operation the spring  30  normally biases the slip clutch  28  to seat one of the notches  42  against the pin  46  such that the spindle  34 , and handle  10  will rotate with one another through the transmission of force via the coupling between the pin  46  and the notch  42 . However, the application of a predetermined amount of torque thorough the handle causes the pin  46  to ride along one of the ramps  44  out of the notch  42 , urging the slip clutch  28  against the biasing force of the spring  30  and disengaging the handle  10  from the spindle  34  to allow the handle  10  to rotate without rotating the spindle  34 . The handle  10  may be reset by reseating the pin  46  onto the notch  42 , whereupon the handle  10  will again be connected to the spindle  34  for co-rotation. 
     Alternatively, after the pin  46  is unseated from one of the notches  42 , it may then be independently rotated 180° with respect to the slip clutch  28  whereupon the pin  46  will become seated within the other of the notches  42  and thereafter provide corotation of the handle  10  and the spindle  34 . In other words, upon successive applications of a predetermined amount of torque, the handle  10  can be continuously rotated clockwise, for example, with the pin  46  intermittently engaging each of the notches  42  at 180° intervals. 
     As is apparent from the foregoing specification, the invention is susceptible of being embodied with various alterations and modifications which may differ particularly from those that have been described in the preceding specification and description. It should be understood that I wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of my contribution to the art.