US 5,472,065 AGranted

Linear motion drive

AssigneeAtoma International Inc.

InventorWilliam E. Vergin

Life of this patent

Estimating the term…

Loading patent…

Abstract

A linear drive, particularly useful for locking or unlocking a door lock mechanism or the like permits manual operation by providing an output shaft that can move freely regardless whether the output shaft is in extended or retracted positions without back driving the motor. The output shaft is coaxially slideably situated over a screw which moves a nut that is theadingly engaged therewith and moves inside the output shaft along the axial direction of the screw. The output shaft is not threadingly engaged with the screw. The output shaft thus is freely movable relative to the screw, which results in essentially zero back drive of the screw and the motor. To provide for manual operation, the nut is automatically moved back to its neutral position every tie the output shaft is extended or retracted by a torsion spring or the like which can store energy therein. Whenever the motor is operated to drive the screw, the spring gear is also rotated, which causes the spring to store energy therein. As soon as the motor is turned off, the energy stored in the spring causes the worm gear to rotate in the direction opposite to the last motor driven direction to move the nut to the neutral position it was in prior to energization of the motor.

Claims16

Dependent claims

A linear drive which permits manual locking and unlocking operation, comprising:

a housing;
an electric motor mounted in said housing;
a screw rotatably mounted in said housing and operatively engaged with said electric motor for rotation thereof;
a hollow output shaft coaxially and telescopingly situated over said screw and freely movable relative to said screw in an axial direction of said screw between an extended position and to a retracted position, said output shaft having an upper abutment and a lower abutment that are spaced apart in said axial direction;
a positioning element threadingly engaged with said screw and located between said abutments, wherein said positioning element is movable between said abutments without moving said output shaft, wherein said positioning element engages said upper abutment to move said output shaft upward to said extended position upon energization of said motor in one direction and engages said lower abutment to move said output shaft downward to said retracted position upon energization of said motor in a direction opposite to said one direction;
and
an automatic positioning element repositioner for automatically moving said said positioning element to a neutral position, without energizing said motor, after said motor has been energized to cause said positioning element to move said output shaft to said extended and retracted positions, said neutral position being the position at which said positioning element is adjacent said lower abutment when said output shaft is in said extended position and being the position at which said positioning element is adjacent said upper abutment when said output shaft is in said retracted position, wherein said repositioner comprises a spring gear rotationally mated with said screw and a helical or torsion spring coaxially positioned relative to said spring gear, said spring being energized by rotational movement of said spring gear imparted by said screw, wherein said spring rotates said spring gear in the opposite direction to the last driven direction, which rotates said screw to move said positioning element to said neutral position,
wherein by virtue of said neutral position of said positioning element being situated adjacent said upper abutment of said output shaft when said output shaft is in said retracted position, said output shaft is manually and repeatedly movable to said extended position and back to said retracted position without back driving said screw and said motor and by virtue of said neutral position of said positioning element being situated adjacent said lower abutment when said output shaft is in said extended position, said output shaft is manually and repeatedly movable to said retracted position and back to said extended position without back driving said screw and said motor.

5 more elements

A linear drive for actuating a door locking mechanism which permits manual locking and unlocking operation, wherein an electric motor drives an output shaft, which is operatively linked to cause locking and unlocking of said locking mechanism, between an extended position and a retracted position, relative to a housing which substantially encloses elements of said linear drive, said linear drive comprising:

a screw rotatably mounted in said housing and operatively engaged with said electric motor for rotation thereof;
a hollow output shaft coaxially and collinearly situated over said screw and freely movable relative to said screw to extended and retracted positions in an axial direction of said screw, said output shaft having an upper abutment and a lower abutment that are spaced apart in said axial direction;
a positioning element threadingly engaged with said screw and located between said abutments, wherein said positioning element is movable between said abutments without moving said output shaft, wherein said positioning element engages said upper abutment to move said output shaft upward to said extended position upon energization of said motor in one direction and engages said lower abutment to move said output shaft downward to said retracted position upon energization of said motor in a direction opposite to said one direction;
and
an automatic positioning element repositioner for automatically moving said said positioning element to a neutral position, without energizing said motor, after said motor has been energized to cause said positioning element to move said output shaft to said extended and retracted positions, said neutral position being the position at which said positioning element is adjacent said lower abutment when said output shaft is in said extended position and being the position at which said positioning element is adjacent said upper abutment when said output shaft is in said retracted position, wherein said repositioner comprises a spring gear rotationally mated with said screw and a helical or torsion spring coaxially positioned relative to said spring gear, said spring being energized by rotational movement of said spring gear imparted by said screw, wherein said spring rotates said spring gear in the opposite direction to the last driven direction, which rotates said screw to move said positioning element to said neutral position,
wherein said output shaft is mechanically linked to said door locking mechanism to permit locking and unlocking of the same, wherein by virtue of said neutral position of said positioning element being situated adjacent said upper abutment of said output shaft when said output shaft is in said retracted position, said output shaft is manually and repeatedly movable to said extended position and back to said retracted position without back driving said screw and said motor and by virtue of said said neutral position of positioning element being situated adjacent said lower abutment when said output shaft is in said extended position, said output shaft is manually and repeatedly movable to said retracted position and back to said extended position without back driving said screw and said motor.

3 more elements

Dependencies are inferred from the claim text.