Actuator Gearbox
An actuator includes a motor and a gearbox connected with the motor. The gearbox has a lower housing, a gear received in the lower housing, and a cover disposed at one end of the lower housing. The lower housing has a support shaft supporting the gear for rotation relative to the lower housing. The support shaft is hollow. A core shaft is inserted into the support shaft. The core shaft is made of a metal material and the support shaft is made of a plastic material.
1 . An actuator gearbox comprising:
a lower housing comprising a bottom end, an opened top end, and a support shaft extending up from the bottom end, the support shaft being hollow and made of a plastic material;
a gear received in the lower housing and supported by the support shaft for rotation relative to the lower housing;
a cover disposed at the top end of the lower housing, the support shaft extending through the cover out of the lower housing; and
a core shaft inserted into the support shaft, the core shaft being made of a metal material.
2 . The gearbox of claim 1 , wherein the support shaft and the lower housing are integrally formed by injection molding.
3 . The gearbox of claim 1 , wherein a center hole is formed in the support shaft, and the core shaft is an interference-fit in the center hole of the support shaft.
4 . The gearbox of claim 3 , wherein the center hole is a blind hole with one end closed and the other end opened.
5 . The gearbox of claim 3 , wherein at least a portion of an outer surface of the core shaft and an inner wall surface of the center hole form a gap there between.
6 . The gearbox of claim 5 , wherein the center hole is a round hole, and said portion of the outer surface of the core shaft is formed with knurls.
7 . The gearbox of claim 5 , wherein the gap between the core shaft and the center hole is formed by a ventilation groove extending axially along the inner wall surface of the center hole.
8 . The gearbox of claim 7 , wherein a ratio of a width of an opening of the ventilation groove in the center hole and a diameter of the center hole ranges from 0.1 to 0.5.
9 . The gearbox of claim 1 , wherein the core shaft is made of steel.
10 . The gearbox of claim 1 , wherein a ratio of a largest diameter of the core shaft to a smallest diameter of the support shaft ranges from 0.1 to 0.75.
11 . An actuator comprising:
a motor; and
a gearbox connected with the motor, the gearbox comprising:
a lower housing comprising a bottom end, an opened top end, and a support shaft extending up from the bottom end, the support shaft being hollow and made of a plastic material;
a gear received in the lower housing and supported on the support shaft for rotation relative to the lower housing;
a cover disposed at the top end of the lower housing, the support shaft extending through the cover out of the lower housing; and
a core shaft inserted into the support shaft, the core shaft being made of a metal material.
12 . The actuator of claim 11 , wherein the gear is a worm gear driven by a worm formed on a shaft of the motor.
13 . The actuator of claim 11 , wherein a center hole is formed in the support shaft, and the core shaft is an interference-fit in the center hole of the support shaft.
14 . The actuator of claim 13 , wherein the center hole is a blind hole with one end closed and the other end opened.
15 . The actuator of claim 13 , wherein at least a portion of an outer surface of the core shaft and an inner wall surface of the center hole form a gap there between.
16 . The actuator of claim 15 , wherein the center hole is a round hole, and said portion of the outer surface of the core shaft is formed with knurls.
17 . The actuator of claim 15 , wherein the gap between the core shaft and the center hole is formed by a ventilation groove extending axially along the inner wall surface of the center hole.
18 . The actuator of claim 17 , wherein a ratio of a width of an opening of the ventilation groove in the center hole and a diameter of the center hole ranges from 0.1 to 0.5.
19 . The actuator of claim 11 , wherein a ratio of a largest diameter of the core shaft to a smallest diameter of the support shaft ranges from 0.1 to 0.75.