Patent Publication Number: US-7721386-B2

Title: Closer arm assembly for an automatic door closer

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application is a divisional of U.S. patent application Ser. No. 11/290,011 which was filed on Nov. 30, 2005, issued as U.S. Pat. No. 7,444,713 on Nov. 4, 2008, the entire content of which is incorporated by reference. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to closer arm assembly for a door closer that automatically closes a door hinged to a door jamb, the closer being mounted to one of the door and the door jamb and including an output shaft that rotates to load a spring when the door is opened, the loaded spring providing the motive force for closing the door. 
   2. Description of the Related Art 
   Automatic door closers are well known, and typically include a housing which can be mounted to one of the door and the jamb, a piston in the housing, a closer spring which acts on the piston, an output shaft which rotates as the piston moves, and hydraulic channels and valves that regulate the closing movement. The rotation of the output shaft is typically translated to linear movement of the piston by a rack and pinion arrangement. An example is disclosed in U.S. Pat. No. 6,618,899. 
   Closer arm arrangements include both single arm and double arm arrangements. In a single arm arrangement, one end of the arm is connected to the output shaft of the closer, and the other end is connected to a shoe in a slide track. Double arm arrangements include regular arm, top jamb, and parallel arm. In the regular arm arrangement, the closer is typically mounted on the top of the door on the hinge side (pull side), and the connecting arm is attached to the frame face on the hinge side at a right angle to the door. In the top jamb arrangement, the closer is typically mounted to the frame face on the opposite to hinge side (push side), and the connecting arm is attached to the door on the opposite to hinge side at a right angle to the door. In the parallel arm arrangement, the closer is typically mounted on the top of the door on the opposite to hinge side (push side), and the connecting arm is attached to the door frame so that it is substantially parallel to both the main arm and the door when the door is closed. The arms pivot relative to each other like scissors as the door opens, their relative angle roughly following the angle of the door relative to the frame. 
   Parallel arm arrangements may include a soffit plate mounted to the soffit of the door frame, and the soffit plate may include a stop in the form of a spring loaded bumper which limits travel of the connecting arm. Known bumpers do not have any cushioning at the contact point with the connecting arm, which results in an undesirable banging noise when the connecting arm hits the bumper. In an arrangement sold by Sargent, the connecting arm contacts a piston which is loaded by a spring in a housing which is only secured by a single bolt. This permits the housing to pivot, but provides only limited resistance to shear stress. U.S. Pat. No. 5,517,720 discloses a bumper having a housing which holds a spring fixed to the soffit plate by a tension pin so that the housing itself makes resilient contact with the connecting arm. Here the tension pin is subject to failure by repeated tensile stress. 
   Parallel arm arrangements may also include a stop mounted on the end of the main arm, the first end of the connecting arm being pivotably connected to the main arm adjacent to the second end. Here too an undesirable banging occurs when the connecting arm hits the stop. 
   Door closer arm arrangements may also include a hold open device which maintains the door in an open position with sufficient holding force to resist automatic closing. When the hold open device is engaged, the door may be closed by applying extra force to overcome a spring force in the hold open device. When the device is disengaged (released), the door will close automatically under the force of the spring in the closer. 
   Known hold open devices typically include a spring-loaded detent in the form of a pin or ball which cooperates with a recess, and is effective between the connecting arm and the soffit plate, or between the two arms at the elbow. A known parallel arm arrangement, sold by Norton Door Controls under the trade name Unitrol, has a fixed pin stop on the main arm and utilizes a holding device including a holding plate having a recess on the main arm, and a housing with a detent loaded by a leaf spring on the connecting arm. The leaf spring is in compression in the engaged position, and requires further compression to release the detent from the socket. Release is achieved by turning a screw a quarter turn against the increasing compression of the leaf spring, which requires using a screw driver. 
   SUMMARY OF THE INVENTION 
   The closer arm assembly according to the invention includes a main arm having a first end and a second end, wherein the first end can be fixed to the output shaft so that the main arm pivots when the output shaft rotates; a connecting arm having a first end and a second end, wherein the first end of the connecting arm is pivotably connected to the main arm and the second end of the connecting arm can be pivotably connected to the other of the door and the jamb; and a stop which contacts the connecting arm to limit relative pivoting of the arms. The stop is provided with a cushion that suppresses noise as the connecting arm contacts the cushion. In a bumper type stop mounted to a soffit plate, this cushion may be a UHMW (ultra high molecular weight) nylon button on the end of the spring which is hit by the connecting arm. In a stop at the elbow joint between the main arm and the connecting arm, the cushion may be a urethane sleeve which is fitted on a cylinder mounted for rotation at the second end of the main arm. 
   The invention also relates to a hold open device that includes a housing fixed to the connecting arm, a plunger extending from the housing for sliding movement through a hole in the connecting arm and into engagement with an engaging feature, a detent which engages the plunger, a hold open spring which loads the detent against the plunger so that the closer cannot automatically close the door when the plunger engages the engaging feature and the hold open spring is compressed, and a release which reduces compression of the hold open spring so that the closer can disengage the plunger from the engaging feature. 
   The hold open spring is preferably a coil spring, and the release is a bolt which is guided in the housing coaxially with the coil spring. The bolt is movable between a first stable position, wherein the hold open spring is compressed so that the closer cannot automatically close the door when the plunger engages the engaging feature, and a second stable position, wherein the compression of the hold open spring is reduced, so that the closer can disengage the plunger from the engaging feature. Preferably, the bolt is provided with a knob, and can be moved from the second stable position to the first stable position by pushing and turning the knob by hand. 
   The engaging feature is preferably positioned so that it aligns with the plunger when the connecting arm is against the stop. Where the stop is mounted on a soffit plate, the engaging feature is provided on the soffit plate. Where the stop is provided at the elbow, the engaging feature is preferably provided on a holding plate fixed to the second end of the main arm. While the engaging feature is preferably a recess which is engaged by a convex surface, the engaging feature may also be a convex surface such as an embedded ball, the end of the plunger being provided with a concave mating surface. 
   In an embodiment having a stop at the elbow, damping of the final stage of opening movement may be provided by a slide track fixed to the door jamb, a shoe which can slide in the track and to which the second end of the connecting arm is pivotably connected, and a spring which can be compressed by the shoe after the stop prevents further relative pivoting of the arms. This arrangement reduces the stress on the stop at the elbow. 
   The features according to the invention not only reduce noise which results when a door is abruptly opened so that the connecting arm hits the stop, but reduce the stress on components such as the mounts for the stop. 
   Other objects and features of the present invention will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. It should be further understood that the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a schematic cross-section of an automatic door closer of the type used with a closer arm assembly according to the invention; 
       FIG. 2  is a plan view of a first embodiment of closer arm assembly according to the invention; 
       FIG. 3  is a cross-section of the bumper mounted to the soffit plate; 
       FIG. 4  is a cross-section of the hold open device in  FIG. 2 ; 
       FIG. 5  is a plan view of a second embodiment of closer arm assembly according to the invention; 
       FIG. 6  is a cross-section of the stop and hold open device of  FIG. 5 ; 
       FIG. 7  is a cross-section of the slide channel damper of  FIG. 5   
       FIG. 8A  is a cross-section of the hold open device of  FIG. 4  in the engaged position with the spring loaded; 
       FIG. 8B  is a cross-section of the hold open device of  FIG. 5  in the engaged position with the spring unloaded; and 
       FIG. 8C  is cross-section of the hold open device of  FIG. 5  in the disengaged position. 
   

   DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS 
   The closer arm assembly according to the present invention is designed for use with an automatic door closer of the type shown in cross section in  FIG. 1 , wherein the closer  10  includes a housing  11  having a cylinder  12  which receives a piston  13 . The piston  13  is acted on by closing spring  14  on one side and incorporates a rack  15  on the other side that turns a pinion  16 . The pinion  16  is fixed to an output shaft  18  that is journaled in the housing  11  and provides the torque for pivoting an arm to close the door. Other features, such as hydraulic lines and valves that regulate the speed of opening and closing the door, are not germane to the invention and are not shown or further described. Other designs of door closer may also be used with the invention, so long as they include the feature of an output shaft that provides torque to close the door. 
     FIG. 2  shows a closer arm assembly including a main arm  20  having a first end  21  and an opposed second end  23 . The first end is provided with a socket  22  which can be fixed nonrotatably to the output shaft  18  of a closer, which typically has a square profile matching the socket. In this case the closer is mounted to a door. The second end  23  is connected to the first end  26  of a connecting arm  25  by a pivot pin  24 . The second end  29  of the connecting arm  25  is pivotably connected to a soffit plate  33  at pivot pin  34 . The soffit plate  33  is mounted to the soffit of a door frame by screw holes  36 , and includes an engaging feature, preferably a recess  35  ( FIG. 4 ), which can be engaged by a hold open device  70  on the connecting arm  25 . The soffit plate  33  also has a shallow channel  37  that facilitates the mounting of stop  40 . 
   Referring to  FIG. 3 , the stop  40  includes a housing  41  having a base  42  with a stud  43  that is received in hole  38  in the channel  37 . The stop  40  is then secured to the soffit plate  33  by flat head machine screws  44 . The housing  41  has a bore  45  that receives a spring  46  having an exposed end  47  fitted with a nylon cushion  48  that abuts a shoulder formed in this end of the bore. The other end of the spring  46  is captured by a plug  49  threaded into the bore  45 ; the spring  46  can therefore be pre-stressed as the plug  49  is threaded in. In operation, the door swings open and the arms  20 ,  25  pivot until the connecting arm  25  hits the cushion  48  and compresses the spring  46  to damp the movement. The cushion  48  suppresses contact noise, while the stud  43  and the screws  44  resist shear stress. 
   Referring to  FIG. 4 , the hold open device  70  contains a plunger  73  which engages a recess  35  in the soffit plate  33  to prevent the closer from automatically closing the door. The plunger has a circumferential recess  74  which is engaged by a spring loaded detent  78  to hold the plunger  73  in the recess  35  against the spring force of the closer, as will be described more fully in conjunction with  FIGS. 8A-8C . 
     FIG. 5  shows a second embodiment of closer arm assembly wherein the closer may be mounted to either the door or the door frame. As in the first embodiment, the main arm  20  has a first end  21  provided with a socket  22  for fixing to the output shaft of a closer. However the second end  23  ( FIG. 6 ) is provided with a holding plate  50  to which a stop  52  is fitted; the first end  26  of the connecting arm  25  is connected at pivot pin  24  adjacent to the stop  52 . As the door opens, the angle between the arms increases until the connecting arm  25  abuts stop  52 , whereupon further relative pivoting of the arms  20 ,  25  is prevented. The holding plate  50  also has engaging features  56 , preferably recesses, which can be engaged by a hold open device  70  on the connecting arm  25  in order to hold the door open against the force of the closer. 
   The connecting arm  25  can be constructed as a first part  27  that is received in a sleeve-like second part  30  having a slot  31  for a threaded bolt  32 . This bolt is screwed into a threaded hole in the first part  27  to permit adjusting the length of the connecting arm  25 . The second end  29  ( FIG. 7 ) is pivotably connected to a damper  60  that may be fixed to either the door and the door frame, opposite from the closer. 
   Referring to  FIG. 6 , the stop  52  includes a rotatably mounted cylinder  53  fitted with a sleeve  54  of high impact resilient material, such as urethane, which serves as a cushion. Since the sleeve  54  can rotate, the stop  52  is not subject to repeated impact at a single point. 
   As shown in  FIG. 7 , the damper  60  includes a slide track  61  constructed as a machined channel in which a shoe  62  can slide; the second end  29  of connecting arm  25  pivots on a rivet  63  that is spun riveted to the shoe  62 . The ends of the track  61  are blocked by end caps  64  which have mounting holes  67  and are held in place by retaining strips  65 . A compression spring  66  is trapped between the shoe  62  and the end cap  64  on the side of the damper toward the door hinge. Thus, when the door is opened until the connecting arm  25  abuts the stop  52  on the main arm  20 , the spring  66  will be compressed until movement of the door ceases. 
   The hold open device  70  shown in  FIG. 8A  includes a housing  71  having a bore  72  that receives a plunger  73  coaxially with a hole  28  in the connecting arm  25 , so that the plunger  73  can engage a recess  56  in the holding plate  50 . The plunger  73  has a circumferential recess  74  that is engaged by a spring loaded detent formed by a steel ball  78  and a coil spring  80 . A bolt  82  is received through guide  86  in the housing  72 . The bolt  82  is fitted with a cross pin  83  which rests on a pair of opposed shoulders  87  to compress the spring when the hold open device is engaged. The shoulders  87  are formed by the inner end of the guide  86 . 
     FIG. 8B  shows the hold open device in the released position, which is achieved by turning a knob  84  on the outer end of bolt  82  until the ends of the cross pin  83  are received in a slot  88  separating the shoulders  87 . Since the bolt  82  moves outward under the force of the hold open spring  80 , it is only necessary to rotate the knob  84  to effect release. The torque applied to the main arm  20  by the automatic door closer can then overcome the force of the hold open spring  80  so that the plunger can retreat. The circumferential recess  74  is ramped on the side facing the holding plate  50  so that the plunger  73  causes the ball  78  to ride up the ramp and compress the spring  80  to the position shown in  FIG. 8C ; an internal retaining ring  76  prevents the plunger  73  from coming out of the bore  72 . When the end of the plunger  73  clears the holding plate  50 , the plunger then snaps back to the position of  FIG. 8B . 
   In order to engage the hold open device, the bolt must be pushed in and turned to get from the configuration of  FIG. 8B  to the configuration of  FIG. 8A . The holding plate  50  is designed so that the plunger  73  is aligned with the recess  56  when the connecting arm  25  is against the stop  52 , and the hold open spring  80  is chosen so that it may be compressed by hand pressure and turned without the use a tool. Note that the force of the hold open spring  80  is only sufficient to prevent the door from closing under the force of the automatic closing device; the door may still be closed by manual pressure sufficient to compress the spring further from the state shown in  FIG. 8A . 
   The holding plate has recesses  56  on both sides of the main arm  20 , so that the plate  50  can be used in both left-handed and right-handed installations. Typically only one recess is provided on each side of the holding plate, and is aligned with the plunger  73  when the connecting arm  20  abuts the stop  52 . Where it is desired to selectively hold the door open in more than one position, more than one recess can be provided on each side of the holding plate. 
   Thus, while there have shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.