Patent ID: 8302438
Filing Date: 2012-11-06
Classification: E05B,Y10T

Abstract:
1. A driving device for an electric lock latch, comprising: a) a housing; b) a motor positioned within the housing and having a power output shaft connected to a drive shaft with an external thread on a part thereof, a diameter (d c) an unequal diameter coil spring having a cylindrical spiral in a middle section thereof, the unequal diameter coil spring corresponding in a spiral direction with the external thread, an axial inner side of the cylindrical spiral outwardly enlarged and forming a first conical spiral, and an opposite side of the cylindrical spiral outwardly enlarged and forming a second conical spiral, such that the unequal diameter coil spring being a shape with small section in the middle and the enlarged conical spiral on both ends, an inner diameter (D d) a lock latch secured to an outer end of the second conical spiral and telescopically moved with the second conical spiral; whereby when the motor drives the drive shaft into a forward rotation or reverse rotation, the external thread of the drive shaft passes the rotation power to the cylindrical spiral and then a rotary motion of the drive shaft is converted into a linear motion of the unequal diameter coil spring for changing an elongation or compression of the unequal diameter coil spring, such that the lock latch is moved by the second conical spiral; when the unequal diameter coil spring is stretched or compressed to a predetermined position, the external thread is idling without driving the unequal diameter coil spring even if the drive shaft is still rotating; when the drive shaft stops rotating and the unequal diameter coil spring is compressed, the cylindrical spiral is fixed by an outer side thereof being against an inner side of the external thread, compressing the lock latch for being in a compression state; when the drive shaft stops rotating and the unequal diameter coil spring is stretched, the cylindrical spiral is fixed by an inner side thereof being against an outer side of the external thread, forming an axial supporting force for the lock latch being in an elongation state.