Patent Application
20150285299
1. Field of the Invention
The present invention relates to an actuator, and more particularly to a linear actuator.
2. Description of the Prior Art
A conventional linear guideway 10 as shown in
The return path of the linear guideway is formed by coupling the two return members 13, 14 together. However, level difference is likely to exist at the conjunction of the two return members, which will cause noise during the movement of the rolling elements. Furthermore, the assembly of the linear guideway must be very precise in order to reduce the level surface, which therefore makes the assembly more difficult, and also increases the manufacturing cost.
The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.
The primary objective of the present invention is to provide a linear actuator without the disadvantages of the conventional linear guideway as described above.
To achieve the above objective, a linear actuator in accordance with the present invention comprises:
an elongated rail extending along an axial direction, and including two rolling grooves at both sides thereof extending in the axial direction;
a first half return member being a hollow square frame integrally formed with two opposite outer end portions and two opposite first return portions, each of the outer end portions including a first engaging slot, each of the first return portions being formed with a first return groove, the first half return member being slidably mounted on the rail in a manner that the rail is engaged in the first engaging slots;
a second half return member being a hollow square frame integrally formed with two opposite inner end portions and two opposite second return portions, each of the inner end portions including two guiding protrusions which extend from a restricting surface of each of the inner end portions, each of the guiding protrusions including a guiding surface which is a semi-circular surface, the inner end portions of the second half return member being connected to the guiding surfaces of the guiding protrusions and each formed with a second engaging slot, each of the second return portions including a second return groove extending along the axial direction and the second return groove being connected to the guiding surfaces, the second half return member being inserted between the two outer end portions of the first half return member, in a manner that the rail is inserted through the second engaging slots, the guiding surfaces of the restricting protrusions of the second half return member are connected to the first return grooves, the second return grooves are in communication with the first return grooves, the guiding surfaces are located toward the first return grooves, the first return grooves cooperate with the second return grooves, and the restricting surfaces of the second half return member to define a return path; and
a slide block with a top surface, two lateral portions, and an engaging slot defined between the two lateral portions and extending along the axial direction, two opposite rolling grooves extending along the axial direction being formed on one surface of the two lateral portions, the slide block being received between the two inner end portions of the second half return member, in a manner that the rail is inserted through the engaging slot of the slide block, the rolling grooves of the slide block cooperate with the rolling grooves of the rail to define a load path which is connected to the guiding surfaces of the second half return member and is in communication with the return path, the load path and the return path are connected to form an endless circulation path in which a plurality of rolling elements are able to move endlessly.
The design of the first and second half return members being hollow square frames and sleeved onto the rail can substantially reduce the number of components of the linear actuator. A circulation path can be formed when the first half return member, the second half return member and the slide block are assembled together, the second half return member is directly disposed in the first radial gap of the first half return member, and the slide block is directly disposed in the second radial gap of the second half return member, which make the assembly much easier. Furthermore, the first and second half return members are integral square frames, there is no level difference in the first and second return grooves of the two half return members, which will prevent noise caused during movement of the rolling elements, reduce impact of the rolling elements against the circulation path, and therefore extending the life of the linear actuator.
The present invention will be clearer from the following description when viewed together with the accompanying drawings, which show, for purpose of illustrations only, the preferred embodiment in accordance with the present invention.
Referring to
The rail 20 is an elongated structure extending along an axial direction X, and includes two rolling grooves 21 at both sides thereof extending in the axial direction X. A direction perpendicular to the axial direction X is defined as a radial direction Y.
The first half return member 30 is integrally formed with two opposite outer end portions 31 and two opposite first return portions 32 located between the two outer end portions 31, so that the two outer end portions 31 and the two first return portions 32 define a hollow square frame. The two first return portions 32 are lower in the radial direction Y than the two outer end portions 31, so as to define a first radial gap 33 between the two outer end portions 31 and the two first return portions 32. Each of the outer end portions 31 includes a first engaging slot 311 and two opposite arc-shaped protrusions 312 on an inner surface of the first engaging slot 311. The first engaging slots 311 are located opposite to each other, and open in a direction different from the direction in which the radial gap 33 opens.
The two outer end portions 31 and the two first return portions 32 each have an inner surface, and an outer surface (the inner surfaces of the two outer end portions 31 are located toward each other, and the inner surfaces of the two first return portions 32 are also located toward each other). On the inner surface of each of the two outer end portions 31 is formed a plurality of positioning portions 313 which are arc-shaped concaves in this embodiment. On the inner surface of each of the first return portions 32 is formed a first return groove 34 which consists of a straight section 341 extending along the axial direction X, and two arc-shaped sections 342 connected to two ends of the straight section 341. Between each of the first return grooves 34 and the first radial gap 33 is formed an inner later surface 35 which is a flat surface. Each of the first return portions 32 is formed with a positioning cavity 36 which is located beside the first return grooves 34, and in the positioning cavity 36 is formed a positioning gap 37. On the outer surface of each of the first return portions 32 is formed an abutting portion 331 which is a groove concaved from the first radial gap 33. In this embodiment, the abutting portion 331 is a stepped groove. The first half return member 30 is slidably mounted on the rail 20 in such a manner that the rail 20 is engaged in the first engaging slots 311, and the opposite arc-shaped protrusions 312 are slidably received in the rolling grooves 21 of the rail 20.
The second half return member 40 is also a hollow square frame integrally formed with two opposite inner end portions 41 and two opposite second return portions 42. Each of the inner end portions 41 includes two guiding protrusions 43 which extend from a restricting surface 411 of each of the inner end portions 41. Each of the guiding protrusions 43 includes a guiding surface 431 which consists of an arc-shaped inner surface 432, an arc-shaped end surface 433 and an arc-shaped outer surface 434 which are sequentially connected to one another to form a semi-circular surface. The arc-shaped inner surface 432 of the inner end portions 41 of the second half return member 40 is connected to the arc-shaped inner surfaces 432 of the guiding protrusions 43 and formed with a second engaging slot 412. Each of the second return portions 42 includes an arc-shaped piece which is formed in the shape of the arc-shaped outer surface 434 of the guiding protrusions 43, and the arc-shaped piece extends along the axial direction X and is connected between the two inner end portions 41. Each of the second return portions 42 includes a second return groove 421 extending along the axial direction X and connected to the arc-shaped outer surface 434. The two inner end portions 41 and the two second return portions 42 define the hollow square frame. The two inner end portions 41 and the two second return portions 42 each have an inner surface, and an outer surface (the inner surfaces of the two inner end portions 41 are located opposite each other and located toward the second return portions 42, and the inner surfaces of the two second return portions 42 are also located toward each other). The two second return portions 42 are lower in the radial direction Y than the two inner end portions 41, so as to define a second radial gap 44 which opens in a direction different from the direction in which the second engaging slots 412 open. On the outer surface of each of the inner end portions 41 is formed a plurality of restricting portions 413 which are semi-circular protrusions in this embodiment, and are shaped to fit in the positioning portions 313 of the outer end portions 31.
The second half return member 40 is inserted between the two outer end portions 31 of the first half return member 30, in such a manner that the restricting portions 413 are engaged in the positioning portions 313, and the guiding protrusions 43 of the second half return member 40 are engaged in the positioning cavities 36 of the first half return member 30. The rail 20 is inserted through the second engaging slots 412, the free ends of the second return portions 42 are abutted against the inner lateral surfaces 35 of the first half return member 30, and the arc-shaped outer surface 434 of the restricting protrusions 43 of the second half return member 40 are connected to the straight sections 341 of the first return grooves 34. The second return grooves 421 are in communication with the straight sections 341 of the first return grooves 34, the arc-shaped end surfaces 433 are connected to the arc-shaped sections 342 of the first return grooves 34, and the restricting surfaces 411 are located toward the arc-shaped sections 342 of the first return grooves 34. By such arrangements, the straight sections 341 and the arc-shaped sections 342 of the first return grooves 34 cooperate with the guiding surfaces 431, the second return grooves 42, and the restricting surfaces 411 of the second half return member 40 to define a return path. The two inner end portions 41 are abutted against the first radial gap 33 of the first half return member 30.
The slide block 50 includes a top surface 51, two lateral portions 52, and an engaging slot 53 defined between the two lateral portions 52 and extending along the axial direction X. Two opposite rolling grooves 521 extending along the axial direction X are formed on one surface of the two lateral portions 52, and another surface of each of the lateral portions 52 is formed an outer groove 522 extending along the axial direction X. Between each of the outer grooves 522 and the top surface 51 is formed a covering portion 54 extending in the radial direction Y. The slide block 50 is received between the two inner end portions 41 of the second half return member 40, in such a manner that the two lateral portions 52 are inserted in the positioning gaps 37 between the inner end portions 41 and the second return portions 42 of the second half return member 40, and the rail 20 is inserted through the engaging slot 53 of the slide block 50. The rolling grooves 521 of the slide block 50 cooperate with the rolling grooves 21 of the rail 20 to define a load path which is connected to the arc-shaped inner surfaces 432 of the second half return member 40 and is in communication with the return path. Hence, the load path and the return path are connected to form an endless circulation path in which the rolling elements 60 can move endlessly. The outer grooves 522 of the slide block 50 are located toward the second radial gap 44 and engaged with second return portions 42 of the second half return member 40, and the covering portions 54 of the slide block 50 are engaged with the abutting portions 331 of the first half return member 30.
The fasteners 70 are inserted through the first half return member 30, the second half return member 40 and the slide block 50 to fix them together.
To assemble the linear actuator of the present invention, it only needs to insert the first half return member 30, the second half return member 40 and the slide block 50 sequentially onto the rail 20, then fix them together by using the fasteners 70.
The design of the first and second half return members 30, 40 being hollow square frames and sleeved onto the rail can substantially reduce the number of components of the linear actuator. A circulation path can be formed when the first half return member 30, the second half return member 40 and the slide block 50 are assembled together, the second half return member 40 is directly disposed in the first radial gap 33 of the first half return member 30, and the slide block 50 is directly disposed in the second radial gap 44 of the second half return member 40, which make the assembly much easier.
Furthermore, the first and second half return members 30, 40 are integral square frames, there is no level difference in the first and second return grooves 34, 421 of the two half return members, which will prevent noise caused during movement of the rolling elements 60, reduce impact of the rolling elements 60 against the circulation path, and therefore extending the life of the linear actuator.
Referring then to
While we have shown and described various embodiments in accordance with the present invention, it is clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.
