Actuator with worm gear positioning mechanism

An actuator with a worm gear positioning mechanism, which includes: a shell casing (10); a motor (20) having a worm rod (21); a transmission assembly (30) having a guiding screw rod (31), a worm gear (32) and a bearing (33), the worm gear (32) having an annular member (321) having an inner circumferential surface (322); an outer tube (40) having an outer circumferential surface (41) attached to the inner circumferential surface (322), the worm gear (32) being positioned between the worm rod (21) and the outer tube (40) on a radial direction; and a telescopic tube (50) disposed in the outer tube (40) and having an inner tube (51) and a screw nut (52), the screw nut (52) moveably screwed with the guiding screw rod (31) to make the inner tube (51) linearly movable relative to the outer tube (40).

BACKGROUND OF THE DISCLOSURE

Technical Field

The present disclosure relates to an actuator, especially to an actuator with a worm gear positioning mechanism.

Description of Related Art

An actuator may be actuated without being driven via gas or liquid, and have advantages of compact volume, low noise generated during operation and low pollution to the ambient environment. Thus, the actuator is commonly used in different fields, for example house, industrial location, medical facility, and farming area.

A transmission assembly of the related-art actuator mainly includes a guiding screw rod, a worm gear, a rear bearing and a positioning bearing. The worm gear, the rear bearing and the positioning bearing are sequentially disposed on the guiding screw rod, and the worm gear is disposed between the rear bearing and the positioning bearing. The guiding screw rod and the worm gear are supported in a shell casing through the rear bearing and the positioning bearing.

However, the installation cost of the positioning bearing is an issue for a long time. Some suppliers utilize the low-cost and low-quality positioning bearing for replacement; thus, the service life of the actuator is greatly shortened. Other suppliers may directly save the cost by not installing the positioning bearing, thus the stability of the guiding screw rod during operation is poor.

Accordingly, the applicant of the present disclosure has devoted himself for improving the mentioned shortages.

SUMMARY OF THE DISCLOSURE

The present disclosure is to provide an actuator with a worm gear positioning mechanism, in which a worm gear is radially positioned, thus the installation cost of a positioning bearing is saved, the operation is stable, and the internal structure is compact.

Accordingly, the present disclosure provides an actuator with a worm gear positioning mechanism, which includes a shell casing, a motor, a transmission assembly, an outer tube, and a telescopic tube. The motor is disposed in the shell casing and has a worm rod. A part of the transmission assembly is disposed in the shell casing. The transmission assembly has a guiding screw rod, a worm gear and a bearing. The bearing is disposed at one end of the guiding screw rod to support the guiding screw rod in the shell casing. The worm gear is adapted to sheathe the guiding screw rod and engaged with the worm rod for transmissions. The worm gear has an annular member. The annular member has an inner circumferential surface. A part of the outer tube is fastened in the shell casing. One end of the outer tube has an outer circumferential surface attached to the inner circumferential surface. The worm gear is positioned between the worm rod and the outer tube on a radial direction. The telescopic tube is disposed in the outer tube and has an inner tube and a screw nut connected to the inner tube. The screw nut is moveably screwed with the guiding screw rod to make the inner tube linearly movable relative to the outer tube.

Advantages achieved by the present disclosure are as follows. With each positioning column and each penetrated hole being mutually engaged and fastened, the outer tube is stably fastened in the shell casing. Through the worm gear being connected to the outer tube, the operation of the guiding screw rod is more reliable. Through each brake component being fastened tightly with each convex column, a torsion spring is driven to generate a radial compression to achieve a braking effect. Through each seal ring being disposed, internal electric components are prevented from being affected by moisture and protected from being damaged.

DETAILED DESCRIPTION OF THE DISCLOSURE

Please refer fromFIG.1toFIG.6, the present disclosure provides an actuator with a worm gear positioning mechanism, which includes a shell casing10, a motor20, a transmission assembly30, an outer tube40, a telescopic tube50.

As shown inFIG.1,FIG.2andFIG.3, the shell casing10is made of a material for example a plastic or an alloy material. The shell casing10mainly includes a lower casing member11and an upper casing member12. The lower casing member11has a tubular housing111and a base112extended from the tubular housing111. A first accommodation zone113, a second accommodation zone114and a third accommodation zone115are sequentially formed from right to left in the base112. A lower positioning column116extended from the base112is disposed at a middle location of the third accommodation zone115. The upper casing member12is correspondingly engaged with the base112of the lower casing member11. An upper positioning column121corresponding to the lower positioning column116is extended from the upper casing member12.

In some embodiments, a first semi-circular recess117is formed at a head end of the base112and a second semi-circular recess122corresponding to the first semi-circular recess117is formed on the upper casing member12to jointly define a circular recess. In addition, a third semi-circular recess118is formed at a distal end of the base112and a fourth semi-circular recess123corresponding to the third semi-circular recess118is formed on the upper casing member12to jointly define another circular recess.

The motor20is an electric motor capable of generating forward and reverse rotations. The motor20is disposed in the tubular housing111of the shell casing10. The motor20includes a worm rod21. The worm rod21is formed in the second accommodation zone114of the base112.

Please refer fromFIG.3toFIG.6, a part of the transmission assembly30is disposed in the first accommodation zone113and the second accommodation zone114of the shell casing10, another part of the transmission assembly30is extended in a direction away from the shell casing10. The transmission assembly30mainly includes a guiding screw rod31, a worm gear32and a bearing33. The bearing33is disposed at one end of the guiding screw rod31, and the guiding screw rod31is supported via the base112of the shell casing10. The worm gear32sheathe the guiding screw rod31and is mutually engaged with the worm rod21for transmissions. The worm gear32moves with the guiding screw rod31. Apart from having a gear part, the worm gear32further has a ring member321. The ring member321is extended from one side of the gear part. As such, the whole structural strength of the worm gear32is increased. The ring member321has an inner circumferential surface322. A first convex column323and a second convex column324are extended from two sides of an axial core of the worm gear32. The second convex column324is extended from the worm gear32in a direction away from the first convex column323.

A part of the outer pipe40is fastened in third accommodation zone115of the shell casing10, another part of the outer pipe40is extended in a direction away from the shell casing10. One end of the outer tube40has an outer circumferential surface41attached to the inner circumferential surface322of the ring member321, thus the worm gear32is positioned between the worm rod21and the outer tube40on the radial direction. The outer tube40has two penetrated holes42located in the third accommodation zone115. One of the penetrated holes42is arranged corresponding to the lower positioning column116to be mutually engaged and fastened. The other penetrated hole42is arranged corresponding to the upper positioning column121to be mutually engaged and fastened.

The telescopic tube50is disposed in the outer tube40. The telescopic tube50mainly has an inner tube51and a screw nut52connected to the inner tube51. The screw nut52is moveably screwed with the guiding screw rod31to make the inner tube51be capable of moving linearly of extraction or retraction relative to the outer tube40.

In some embodiments, the actuator with the worm gear32positioning mechanism of the present disclosure further includes a rear supporter60. The rear supporter60covers the bearing33and is jointly disposed in the first accommodation zone113of the base112. The rear supporter60has an annular mounting slot61.

In some embodiments, the actuator with the worm gear32positioning mechanism of the present disclosure further includes a first brake component70and a second brake component75. The first brake component70is annularly and tightly disposed on an outer surface of the first convex column323, and one end thereof is fastened on the rear supporter60. The second brake component75is annularly and tightly disposed on an outer surface of the second convex column324, and one end thereof is fastened on the outer tube40. In some embodiments, the first brake component70and the second brake component75are a torsion spring. Through the first convex column323and the second convex column324rotating, the torsion spring is driven to generate a radial compression to achieve a braking effect.

In some embodiments, the actuator with the worm gear32positioning mechanism of the present disclosure further includes a first seal ring80and a second seal ring85. The first seal ring80is disposed in the second semi-circular recess117, the second semi-circular recess122and the annular mounting slot61. The second seal ring85sheathes an outer surface of the outer tube40and is disposed in the third semi-circular recess118and the fourth semi-circular recess123.