Abstract:
A door closer power adjusting device for a door closer having a spindle driven by a compressed spring with a movable plate for adjusting spring compression, or with a screw for adjusting spring compression, between a high and low level of compression. A powered unit moves the plate in a first direction to achieve the low level of compression and in a second direction to achieve the high level of compression. A switch activates the powered unit in the first direction and a first switch is engaged when the spring is compressed to the low level of compression to deactivate the powered unit. A timing circuit activates the powered unit in a second direction after passage of a predetermined time. A second switch is engaged when the spring is compressed to the high level of compression to deactivate the powered unit.

Description:
BACKGROUND OF THE INVENTION 
   The present invention relates to spring powered door closers, such as disclosed in U.S. Pat. Nos. 3,246,362, 4,064,589, and 5,666,692, which disclosures are incorporated herein by reference. In such closers it is known that the closing power or force required to open the door against the spring force of the closer can be adjusted by providing greater or lesser compression of the springs in the closer. This can be accomplished by rotating a screw that moves a plate internally of the closer body that further compresses the spring, or allows the spring to expand, depending upon the direction of rotation of the screw. Such an arrangement is disclosed in the &#39;692 patent. 
   SUMMARY OF THE INVENTION 
   The present invention allows the power of the closer to be adjusted by a user through the use of a powered arrangement, rather than through a manual operation by the user. Such a device is particularly useful to allow for greater accessibility to spaces closed by heavy doors, or doors with high powered door closers. In some situations, it is necessary to have a door closer high powered, such as to assure that the door remains in a closed position when the door is subject to high wind forces, or where the ambient pressure in the building or closed space is significantly different from the ambient pressure outside of the building or closed space. 
   A drawback of a high powered door closer is that it may be difficult for all persons to open the door against the normal high power of the closer. For this reason, a device according to the present invention is provided to adjust the power of the door closer to a much lower power, upon receipt of a signal from such a user, so that the door can be opened more easily. After a set time, the power of the door closer will be returned to the higher power level to provide the security to the building or space normally provided by the closed door. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
       FIG. 1  illustrates a plan view of the interior of a door closer power adjusting device embodying the principles of the present invention. 
       FIG. 2  illustrates a plan view of the interior of an alternative embodiment of a door closer power adjusting device embodying the principles of the present invention. 
       FIG. 3  illustrates a side view of the interior of the device of  FIG. 2 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   In an embodiment of the invention, as illustrated in  FIG. 1 , door closer power adjusting device  10  includes a housing  12  for accommodating a number of internal components. One of the components, a powered unit in the form of a high torque motor  20 , such as a 12 volt portable drill motor, can be used to rotate a shaft  22  connected, via an appropriate interface, to a power adjustment screw  24  of a door closer  26 . The motor  20  and shaft  22  can be located in a door transom  28  so that they are not visible to the user during normal usage. Other types of powered units may be utilized to move a plate  27  in the door closer  26  against which one or more springs  29  in the door closer are compressed, including other types of motors, gear arrangements, and hydraulic or pneumatic movable pistons which may move the plate directly without use of a rotatable adjustment screw. 
   A switch  30  may be provided to allow the user to activate the motor  20  to rotate the power adjustment screw  24  to lower the power required to open the door. The switch may be in the form of a touch pad, push button, toggle switch, motion detector, infra red proximity switch or other known arrangements, including a remotely operated switch using a wired or wireless connection. 
   The shaft  22  of the motor  20  can carry an external thread  32 , on which is carried a traveling nut  34 , which moves into engagement with a limit switch  36  to deactivate the motor once the power adjustment screw  24  has rotated sufficiently to lower the power of the door closer  26  to an appropriate level. The limit switch  36  may also be carried on the nut  34  and moved into engagement with a fixed stop member to operate the switch once the shaft has rotated sufficiently. A similar arrangement could be used if a movable piston were used. 
   A signal device  38 , such as a green light, for example a green LED, can be illuminated to signal to the user that the door closer  26  has reached the low power state. Other types of visible or audible signaling devices could also be used. 
   After the passage of a predetermined time period, as determined by an electronic timing circuit  40 , sending a signal through a control unit  41  that all of the electrical devices are connected to, the motor  20  is reversed and the shaft  22  is rotated in the opposite direction to return the closer  26  to the higher power setting. Again, the nut  34  carried on the shaft  22  can be used to engage the limit switch  36  to terminate operation of the motor  20  when the shaft  22  has rotated a sufficient amount to return the closer  26  to the high power setting. Thus, the two switching functions associated with the movement of the nut  34  on the shaft  22  can be accomplished by a single switch having two engagement positions. 
   A further signal device  42 , such as a red light, for example, a red LED, can be illuminated to signal to the user that the door closer  26  is no longer in the low power state and/or is in the high power state. This signal device  42  may be activated as soon as the motor  20  is activated to return the closer  26  to the high power setting, and may remain activated until such time as the closer is fully returned to the low power setting. Again, other types of signaling devices as described above could be used. 
   The motor  20  may be powered through a normal 110 volt ac power line  44 , which electrical power is converted to 12 volt dc power at a voltage converter unit  46 . 
   An override switch  48  may be provided to return the power setting for the door closer  26  to the high power, in advance of the normal time delay, if desired. This switch  48  may be constructed identically to or differently from the switch  30 . 
   Also, a complete override switch  50  may be provided to disconnect the switches  30 ,  48  for changing the power setting for the door closer  26  if that is desired as well. This complete override switch may be located remotely from the door. 
   In another embodiment of the invention, as illustrated in  FIGS. 2 and 3 , door closer power adjusting device  110  includes a housing  112  for accommodating a number of internal components. One of the components, a powered unit in the form of a high torque motor  120 , such as a 12 volt portable drill motor, can be used to rotate a shaft  122  connected, via an appropriate interface, to a power adjustment screw  124  of a door closer  126  of the type described above. The motor  120  and shaft  122  can be located in a door transom  128  so that they are not visible to the user during normal usage. Other types of powered units may be utilized to move a plate in the door closer  126  against which one or more springs in the door closer are compressed, including other types of motors, gear arrangements, and hydraulic or pneumatic movable pistons which may move the plate directly without use of a rotatable adjustment screw. 
   A switch as described above with regard to switch  30 , may be provided to allow the user to activate the motor  120  to rotate the power adjustment screw  124  to lower the power required to open the door. The switch may be in the form of a touch pad, push button, toggle switch, motion detector, infra red proximity switch or other known arrangements, including a remotely operated switch using a wired or wireless connection. 
   The shaft  122  of the motor  120  can carry an external thread  132 , on which is carried a traveling nut  134 , which moves into engagement with a limit switch  135 ,  136  at each end of its travel to deactivate the motor once the power adjustment screw  124  has rotated sufficiently to lower the power of the door closer  126  to an appropriate level, or has returned to its initial, full power position. The two positions of the nut  134  can thus be detected by two separate switches. A similar arrangement could be used if a movable piston were used. 
   As in the embodiment described above with respect to  FIG. 1 , a signal device (not separately shown here), such as a green light, for example a green LED, can be illuminated to signal to the user that the door closer  126  has reached the low power state. Other types of visible or audible signaling devices could also be used. 
   After the passage of a predetermined time period, as determined by an electronic timing circuit as described previously, sending a signal through a control unit that all of the electrical devices are connected to, the motor  120  is reversed and the shaft  122  is rotated in the opposite direction to return the closer  126  to the higher power setting. Again, the nut  134  carried on the shaft  122  can be used to engage the first limit switch  135  to terminate operation of the motor  120  when the shaft  122  has rotated a sufficient amount to return the closer  126  to the high power setting. The two switches  135 ,  136  could be incorporated into a single switch if desired. 
   A further signal device as described with respect to  FIG. 1 , such as a red light, for example, a red LED, can be illuminated to signal to the user that the door closer  126  is no longer in the low power state and/or is in the high power state. This signal device may be activated as soon as the motor  120  is activated to return the closer  126  to the high power setting, and may remain activated until such time as the closer is fully returned to the low power setting. Again, other types of signaling devices as described above could be used. 
   The motor  120  may be powered through a normal 110 volt ac as described above, which electrical power is converted to 12 volt dc power at a voltage converter unit. 
   An override switch as described above may be provided to return the power setting for the door closer  126  to the high power, in advance of the normal time delay, if desired. This switch may be constructed identically to or differently from the other user operable switches. 
   Also, as described above, a complete override switch may be provided to disconnect the user operated switches for changing the power setting for the door closer  126  if that is desired as well. This complete override switch may be located remotely from the door. 
   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 we wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of our contribution to the art.