Speed control mechanism for revolving doors

Claim 2

A speed control mechanism for a revolving door comprising, in combination: a motor having a field winding and an armature, said motor being coupled to and rotating said revolving door at a speed proportional to the rotational speed of said armature; and a control circuit electrically coupled to said motor for controlling the operation thereof including field-energizing means coupled to and energizing said field winding thereof, armature-energizing means coupled to and energizing said armature to thereby rotate said revolving door, and a braking circuit included in said coupling between said armature and said armature energizing means including sensing means comprising a pair of resistors forming a voltage divider connected across said armature for sensing the speed of rotation of said armature by measuring the voltage across said armature, dynamic-braking means comprising resistance means, and a relay for disconnecting said armature from said armature-energizing means and for connecting thereto said dynamic-braking means, variable resistance means connected in series with said voltage divider for varying the established maximum speed of rotation of said revolving door, said relay being operated when the voltage across said voltage divider reaches a predetermined value to connect said dynamicbraking means to said armature and being held operated by the voltage across said armature until the rotational speed of said armature slows to the point where the voltage across said armature is less than the relay dropout voltage.

Claim 3

The speed control mechanism of claim 1, further including a unijuNction transistor, a pulse transformer and a silicon control rectifier having a gate electrode, said unijunction transistor being rendered conductive when the voltage across said voltage divider reaches a predetermined value and conducting a pulse through said pulse transformer, said pulse being coupled by said pulse transformer to said gate electrode of said silicon control rectifier to trigger said silicon control rectifier conductive, said silicon control rectifier upon being rendered conductive permitting current flow through said relay to operate said relay.

Claim 4

The speed control mechanism of claim 2, wherein said variable resistance means is adjusted so that the voltage across said voltage divider reaches the conduction point of said unijunction transistor at the desired maximum speed of rotation of said revolving door.

Claim 5

A speed control mechanism for a revolving door comprising, in combination: a motor having a field winding and an armature, said motor being coupled to and rotating said revolving door at a speed proportional to the rotational speed of said armature; a cam plate having a cam thereon, said cam plate being secured to and rotated by a shaft of said revolving door as the latter rotates, and a control circuit electrically coupled to said motor for controlling the operation thereof including field-energizing means coupled to and energizing said field winding thereof, armature-energizing means coupled to and energizing said armature thereof to rotate said armature to thereby rotate said revolving door, and a braking circuit included in said coupling between said armature and said armature energizing means including sensing means for sensing the speed of rotation of said armature, dynamic-braking means, and switching means operated by said sensing means to disconnect said armature from said armature-energizing means and to connect thereto said dynamic-braking means to thereby prevent said revolving door from being rotated faster than a preestablished maximum rotational speed, said control circuit further including speed control means and stopping means for controlling the output of said armature-energizing means to thereby control the rotational speed of said armature, a first and second relay means, a first and a second switch means operated by said cam as said cam plate rotates, said first switch means having a normally open contact which is closed by said cam when said revolving door is initially rotated to couple said source of power to said first relay means, said first relay means upon being energized coupling said armature-energizing means to said armature to energize said armature to rotate said revolving door, said second switch means having a normally open contact which is momentarily closed by said cam when said revolving door rotates to couple said source of power to said second relay means, said second relay means upon being energized closing a holding circuit therefor through said first switch means and disconnecting said speed control means and connecting said stopping means to said armature-energizing means, said stopping means causing said armature-energizing means to slow the rotation of said armature whereby said revolving door will stop when said cam on said cam plate operates said first switch means to open said normally open contact to disconnect said armature-energizing means from said armature, said normally open contact upon being opened opening said holding circuit for said second relay means.

Claim 6

A speed control mechanism for a revolving door comprising, in combination: a motor having a field winding and an armature, said motor being coupled to and rotating said revolving door at a speed proportional to the rotational speed of said armature; a cam plate having a cam thereon, said cam plate being secured to and rotated by a shaft of said revolving door as the latter rotates, and a control circuit electrically coupled to said motor for controlling the operation thereof including field-energizing means coupled to and energizing said field winding thereof, armature-energizing means coupled to and energizing said armature thereof to rotate said armature to thereby rotate said revolving door, and a braking circuit included in said coupling between said armature and said armature energizing means including sensing means for sensing the speed of rotation of said armature, dynamic-braking means, and switching means operated by said sensing means to disconnect said armature from said armature-energizing means and to connect thereto said dynamic-braking means to thereby prevent said revolving door from being rotated faster than a preestablished maximum rotational speed, said control circuit further including speed control means and stopping means for controlling the output of said armature-energizing means to thereby control the rotational speed of said armature, a first and second relay means, a first and a second switch means operated by said cam as said cam plate rotates, said first switch means having a normally open contact which is closed by said cam when said revolving door is initially rotated to couple said source of power to said first relay means, said first relay means upon being energized coupling said armature-energizing means to said armature to energize said armature to rotate said revolving door, said second switch means having a normally open contact which is momentarily closed by said cam when said revolving door rotates to couple said source of power to said second relay means, said second relay means upon being energized closing a holding circuit therefor through said first switch means and disconnecting said speed control means and connecting said stopping means to said armature-energizing means, said stopping means causing said armature-energizing means to slow the rotation of said armature whereby said revolving door will stop when said cam on said cam plate operates said first switch means to open said normally open contact to disconnect said armature-energizing means from said armature, said normally open contact upon being opened opening said holding circuit for said second relay means.