CROSS-REFERENCE TO RELATED APPLICATION

This non-provisional application claims priority under 35 U.S.C. § 119(a) to Patent Application No. 202011441288.8 filed in China, P.R.C. on Dec. 8, 2020, the entire contents of which are hereby incorporated by reference.

BACKGROUND

Technical Field

The instant disclosure relates to a ball screw assembly and an open nut of the ball screw assembly, and in particular, to an open nut assembled with a two-piece circulator and a ball screw assembly using the opening nut.

Related Art

The ball screw assembly known to the inventor is provided for converting a rotation motion into a linear motion through the cooperation between the screw and the nut. By the cooperation between the ball nut provided with balls rolling in the circulating race and the screw provided with a spiral groove, the friction between the ball nut and the screw can be reduced during the operation.

Most of the ball nuts known to the inventor have complete cylinder shapes. When the length of the screw is longer and is provided with a supporting holder for preventing the screw from sagging, a resilient mechanism is provided on the supporting holder. Hence, when the ball nut rotates around the screw and passes the portion of the screw having the supporting holder, the supporting holder is temporally moved away from the screw through the resilient mechanism. Next, after the ball nut passes the portion of the screw having the supporting holder, the resilient mechanism moves the supporting holder back to the supporting position for providing a sufficient supporting force for the screw.

SUMMARY

However, when taking the aforementioned configurations, additional resilient mechanisms are configured at the supporting holders. Furthermore, when the supporting holder is at a position away from the screw, the portion of the screw corresponding to the supporting holder may sag due to its weight. As a result, when the open nut passes the portion of the screw having the supporting holder at the position away from the screw, the screw may encounter deflection, or the balls may not roll in the threaded groove properly due to the bending of the screw. Consequently, during the application of the ball guider device, the manufacturing precision becomes an issue and is to be considered.

The prior art discloses a ball nut with an opening corresponding to the supporting holder, which can smoothly pass without the resilience of the supporting holder. In addition, it has been disclosed that a circulator is disposed at the opening of the ball nut, so that the ball can circularly roll in the ball nut. However, the circulator is usually a one-piece structure integrally formed, and an additional insertion member is used for manufacturing the mold of the circulator to form a ball race, which is relatively troublesome to manufacture and also causes the development of a module more complicated.

In view of these, one embodiment of the instant disclosure provides a ball screw assembly. The ball screw assembly includes a guider, an open nut, and a ball circulating assembly. The guider has a central axis and a spiral channel, where the spiral channel is annularly disposed around an outer periphery of the guider. The open nut includes an axial cylinder, an open shield, and two circulators. The axial cylinder has an axial opening, and the axial cylinder has a first axial wall and a second axial wall respectively located at two opposite sides of the axial opening. The axial cylinder includes an inner circular wall and an outer circular wall, where the inner circular wall has an inner spiral channel, and the inner spiral channel and the spiral channel of the guider correspond to each other and form an inner ball race. The inner peripheral wall and the outer circular wall of the axial cylinder correspond to each other and form an outer ball race. The two circulators are respectively disposed on the first axial wall and the second axial wall. Each of the circulators includes an inner member and an outer member. The inner member includes a main body, a plurality of through holes, and a plurality of through slots. The through holes and the through slots are disposed in the main body, and the through holes and the through slots are disposed in a one-to-one correspondence. The through slots are provided on a long side of the main body. The outer member is assembled to the inner member correspondingly. The outer member includes a plurality of arc-shaped sliding grooves, where a first end of each of the arc-shaped sliding grooves corresponds to the corresponding through hole, and a second end at an opposite side of each of the arc-shaped sliding grooves corresponds to the corresponding through slots. The inner member and the outer member form a ball race after the inner member and the outer member are combined with each other. The ball circulating assembly includes a plurality of balls, where the inner ball race, the ball races of the two circulators, and the outer ball race form a ball circulating race, and the ball circulating assembly rolls in the ball circulating race.

In some embodiments, the through holes are a plurality of circular through holes, and the through slots are a plurality of arc-shaped through slots. The main body has a first surface and a second surface located on two opposite parallel sides of the main body, and the main body has a plurality of communication channels disposed on the second surface. The circular through holes, the communication channels, and the arc-shaped through slots are disposed in a one-to-one correspondence. The circular through holes and the arc-shaped through slots run through the first surface and the second surface, and each of the communication channels is in communication with the corresponding circular through hole and the corresponding arc-shaped through slot.

In some embodiments, a width of each of the communication channels decreases toward a middle portion of the communication channel from a connection portion between the communication channel and the circular through hole and from a connection portion between the communication channel and the arc-shaped through slot.

In some embodiments, the two circulators are respectively fixed to the axial cylinder through screwing or bolting.

In some embodiments, two positioning posts protrude from a side of the inner member away from the outer member, and the first axial wall and the second axial wall of the axial cylinder respectively have a first positioning hole. Surfaces of the open shield parallel to the first axial wall and the second axial wall respectively have a second positioning hole, and the two positioning posts of each of the inner members respectively pass through and assembled in the corresponding first positioning hole and the corresponding second positioning hole.

In some embodiments, the outer member further includes a plurality of guiding protrusions, where each of the guiding protrusions corresponds to and extends toward the second end of the corresponding arc-shaped sliding groove.

In the above embodiment, each of the guiding protrusions has an arc-shaped surface, where the arc-shaped surface corresponds to a radian of the arc-shaped sliding groove and bends toward the inner spiral channel.

In addition, an embodiment of the instant disclosure provides an open nut that may be used for the ball screw assembly. The open nut includes an axial cylinder, an open shield, and two circulators. The axial cylinder has an axial opening. The axial cylinder has a first axial wall and a second axial wall respectively located at two opposite sides of the axial opening. The axial cylinder includes an inner circular wall and an outer circular wall, where the inner circular wall has a plurality of inner spiral channels. The open shield is coaxially fitted over an outer periphery of the axial cylinder, and the open shield has an inner peripheral wall. The inner peripheral wall and the outer circular wall of the axial cylinder correspond to each other and form an outer ball race. The two circulators are respectively disposed on the first axial wall and the second axial wall. Each of the circulators includes an inner member and an outer member. The inner member includes a main body, a plurality of through holes, and a plurality of through slots. The through holes and the through slots are disposed in the main body, and the through holes and the through slots are disposed in a one-to-one correspondence. The through slots are provided on a long side of the main body. The outer member is assembled to the inner member correspondingly. The outer member includes a plurality of arc-shaped sliding grooves, a first end of each of the arc-shaped sliding grooves corresponds to the corresponding through hole, and a second end at an opposite side of each of the arc-shaped sliding grooves corresponds to the corresponding through slot. The inner member and the outer member form a ball race after the inner member and the outer member are combined with each other. One ends of the through holes of the inner member away from the outer member correspond to the outer ball race. The through slots of the inner member and the arc-shaped sliding grooves of the outer member are respectively in communication with the inner spiral channels, and one of the inner spiral channels, the ball races of the two circulators, and the outer ball race form a ball circulating race.

In some embodiments, the through holes are a plurality of circular through holes, and the through slots are a plurality of arc-shaped through slots. The main body has a first surface and a second surface located on two opposite parallel sides of the main body, and the main body has a plurality of communication channels disposed on the second surface. The circular through holes, the communication channels, and the arc-shaped through slots are disposed in a one-to-one correspondence. The circular through holes and the arc-shaped through slots run through the first surface and the second surface, and each of the communication channels is in communication with the corresponding circular through hole and the corresponding arc-shaped through slot.

In some embodiments, a width of each of the communication channels decreases toward a middle portion of the communication channel from a connection portion between the communication channel and the circular through hole and from a connection portion between the communication channel and the arc-shaped through slot.

In some embodiments, the two circulators are respectively fixed to the axial cylinder through screwing or bolting.

In some embodiments, two positioning posts protrude from a side of the inner member away from the outer member, and the first axial wall and the second axial wall of the axial cylinder respectively have a first positioning hole. Surfaces of the open shield parallel to the first axial wall and the second axial wall respectively have a second positioning hole, and the two positioning posts of each of the inner members respectively pass through and assembled in the corresponding first positioning hole and the corresponding second positioning hole.

In some embodiments, the outer member further includes a plurality of guiding protrusions, where each of the guiding protrusions corresponds to and extends toward the second end of the corresponding arc-shaped sliding groove.

In some embodiments, each of the guiding protrusions has an arc-shaped surface, where the arc-shaped surface corresponds to a radian of the arc-shaped sliding groove and bends toward the inner spiral channels.

In some embodiments, the inner member and outer member are made of different materials.

In the above embodiment, for example, the inner member may be made of a plastic material, and the outer member may be made of a metal material.

Therefore, in the ball screw assembly and the open nut according to one or some embodiments of the instant disclosure, the circulators separated into two pieces can be quickly positioned and assembled relative to each other by the correspondence of shapes of the through holes and the through slots of the inner member and shapes of the arc-shaped sliding grooves of the outer member. Moreover, a mold for manufacturing the inner member and the outer member may have a simplified structure, thus shortening manufacturing duration for the product. Moreover, materials selected for the inner member and the outer member may be changed according to the use environment, the service life, manufacturing costs, and the like. Alternatively, the inner member or the outer member may be replaced when worn out. Furthermore, by virtue of the two-piece structure, after the inner member is assembled on the axial cylinder, balls can be filled through the structures of the through hole and the through slots without using additional elements such as a baffle, thus facilitating the ball filling procedure.

Detailed features and advantages of the instant disclosure are described in detail in the following implementations, which are sufficient for any person skilled in the art to understand the technical content of the instant disclosure and implement the operations accordingly. According to the content disclosed in this specification, the scope of patent application, and the drawings, any person skilled in the art can easily understand related objectives and advantages of the instant disclosure.

