Small electric cylinder

Abstract

The utility model relates to a small electric cylinder which comprises a ball nut pair, a front end cover, a first bearing, a shell, a hollow rotor shaft, a stator, a rear end cover, an encoder, an encoder rear end cover, a second bearing and magnetic steel. The front end cover tightly presses the outer ring of the first bearing and is connected with one end of the shell, the other end of the shell, the stator and the rear end cover are sequentially connected, the second bearing is installed on the hollow rotor shaft, the magnetic steel is installed at the tail end of the hollow rotor shaft, and the encoder is installed between the hollow rotor shaft and the encoder rear end cover. Compared with the prior art, the utility model has the advantages of high rigidity, high precision, small volume, easy assembly and the like.

Description

Technical Field

[0001] This utility model relates to an electric cylinder, and more particularly to a small electric cylinder. Background Technology

[0002] In the semiconductor and 3C fields, miniature electric cylinders play an important role in chip manufacturing equipment, product assembly and production. Their structural complexity, finished product manufacturing and assembly processes, structural rigidity and stability, operating accuracy and application space have a significant impact on their application in actual products.

[0003] In patent publication number JP4918234B2, the ball nut is installed inside the hollow shaft of the motor, and the bearing is installed in the large diameter part of the hollow shaft. Meanwhile, in patent publication number JP2012154378A, the ball nut is installed inside the hollow shaft, and screws ensure the synchronous rotation of the ball nut.

[0004] The aforementioned existing patents have the following disadvantages:

[0005] 1. Low linear accuracy: The ball screw is connected to the front bracket through the bushing, which increases the fit error of the overall structure; there is no clearance elimination treatment between the support bearings, resulting in a certain axial movement error.

[0006] 2. High assembly difficulty: The machine has numerous parts and a complex structure. The motor stator needs to be installed and fixed inside the housing. The hollow rotor shaft has precision, slender guide holes, requiring the coaxiality of the rotor's outer diameter with the stator's inner diameter to be ensured. Furthermore, due to the integrated structure, the installation sequence is complex, making disassembly and repair difficult. The lead screw and rotor need to be assembled first; after the front end is assembled, the rotor's rear shaft and bearing rear end cover need to be assembled simultaneously, making overall assembly challenging.

[0007] 3. High machining difficulty and complex process control: The hollow rotor shaft has precision elongated guide holes inside and multiple precision positioning stepped surfaces on the outside. The housing itself is relatively long, and most of the interior of the housing consists of precision positioning stepped surfaces. At the same time, it is difficult to inspect the dimensions of the parts and monitor the process data. Utility Model Content

[0008] The purpose of this invention is to overcome the defects of the existing technology and provide a miniature electric cylinder.

[0009] The objective of this utility model can be achieved through the following technical solutions:

[0010] According to one aspect of the present invention, a miniature electric cylinder is provided, comprising a ball nut assembly, a front end cover, a first bearing, a housing, a hollow rotor shaft, a stator, a rear end cover, an encoder, an encoder rear end cover, a second bearing, and a magnet. The ball nut assembly passes through the first bearing and is connected to the hollow rotor shaft. The front end cover presses against the outer ring of the first bearing and is connected to one end of the housing. The other end of the housing, the stator, and the rear end cover are connected in sequence. The second bearing is mounted on the hollow rotor shaft. A magnet is mounted at the end of the hollow rotor shaft. The encoder is mounted between the hollow rotor shaft and the encoder rear end cover.

[0011] As a preferred technical solution, the ball nut assembly includes a ball screw and a ball nut respectively connected to the hollow rotor shaft. The ball screw is connected to a first screw, and the connection is coated with a first adhesive.

[0012] As a preferred technical solution, the ball nut includes a flange portion, a smooth shaft portion, and a threaded portion. The flange portion is connected to the inner ring of the first bearing, and the threaded portion is connected to the hollow rotor shaft. The connection is coated with a second adhesive.

[0013] As a preferred technical solution, one end of the front cover is positioned by a positioning port and connected to the housing, while the other end is provided with a flange positioning surface.

[0014] As a preferred technical solution, there are two first bearings, and a precision washer is provided between the two first bearings.

[0015] As a preferred technical solution, the housing is provided with an outer stop positioning circle that mates with the outer circle of the stator, and the rear end cover is provided with an end cover positioning circle that mates with the inner hole of the stator.

[0016] As a preferred technical solution, a wave-shaped washer is provided between the rear end cover and the hollow rotor shaft, and a third adhesive is applied to the connection between the magnet and the hollow rotor shaft.

[0017] As a preferred technical solution, the ball screw is provided with a first flat wire, the ball nut is provided with a second flat wire, and the hollow rotor shaft is provided with a third flat wire at its end.

[0018] As a preferred technical solution, the electric cylinder further includes a mounting screw, which passes through the rear cover through hole and the stator through hole and is connected to the housing threaded hole; or the mounting screw passes through the encoder rear cover through hole, the rear cover through hole and the stator through hole and is connected to the housing threaded hole.

[0019] As a preferred technical solution, the electric cylinder further includes a guide rail mounting plate, a guide rail pair, an L-shaped plate, an anti-loosening nut, and a fixing pin. The guide rail pair is mounted on the guide rail mounting plate and includes a guide rail and a slider. The slider moves on the guide rail. The guide rail mounting plate is mounted on the housing and positioned by the fixing pin, and then connected by screws. The end face of the ball screw is connected to the L-shaped plate and connected by the anti-loosening nut.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1) High rigidity: The housing is equipped with two bearings, with inner and outer rings locked together to restrict radial and axial movement; the rear end cover has one bearing to restrict radial movement.

[0022] 2) High precision: The housing is equipped with two bearings, with precision shims between the bearings to eliminate axial clearance.

[0023] 3) Small size: Fewer parts, smaller size, and compact structure

[0024] 4) Easy assembly: The parts are equipped with multiple flat screws, and the front cover is connected by screws, which facilitates the assembly, control and maintenance of each component.

[0025] 5) Easy to process: The high-precision mating surfaces of the parts have small areas. Only the hollow rotor shaft is a slender part, while the rest of the parts are mostly square or cylindrical. Attached Figure Description

[0026] Figure 1 This is a three-dimensional structural diagram of Embodiment 1 of the present invention;

[0027] Figure 2 This is a cross-sectional view of Embodiment 1 of the present invention. Figure 1 ;

[0028] Figure 3 for Figure 2 A magnified structural diagram of part A;

[0029] Figure 4 This is a cross-sectional view of Embodiment 1 of the present invention. Figure 2 ;

[0030] Figure 5 This is a three-dimensional structural schematic diagram of Embodiment 2 of the present invention;

[0031] Figure 6 This is a cross-sectional view of Embodiment 2 of the present invention. Figure 1 ;

[0032] Figure 7 This is a cross-sectional view of Embodiment 2 of the present invention. Figure 2 ;

[0033] 1 is a ball screw, 2 is a front end cover, 3 is a ball nut, 4 is a first bearing, 5 is a precision washer, 6 is a housing, 7 is a hollow rotor shaft, 8 is a stator, 9 is a first screw, 10 is a rear end cover, 11 is a protective cover, 12 is a wave washer, 13 is an encoder rear end cover, 14 is a second bearing, 15 is a magnet, 16 is a guide rail mounting plate, 17 is a guide rail, 18 is a slider, 19L is a profile plate, 20 is a lock nut, and 21 is a fixing pin.

[0034] 1a is the first flat wire, 1b is the first adhesive, 2a is the flange positioning surface, 2b is the positioning port, 3a is the second flat wire, 3b is the optical shaft part, 6a is the outer stop positioning circle, 7a is the second adhesive, 7b is the third adhesive, and 10a is the end cap positioning circle. Detailed Implementation

[0035] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of the present utility model. Based on the embodiments of the present utility model, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of the present utility model.

[0036] Example

[0037] like Figure 1-4 As shown, a miniature electric cylinder includes a ball nut assembly, a front end cover 2, a first bearing 4, a housing 6, a hollow rotor shaft 7, a stator 8, a rear end cover 10, an encoder, an encoder rear end cover 13, a second bearing 14, and a magnet 15. The ball nut assembly passes through the first bearing 4 and connects to the hollow rotor shaft 7. The front end cover 2 presses against the outer ring of the first bearing 4 and connects to one end of the housing 6. The other end of the housing 6, the stator 8, and the rear end cover 10 are connected in sequence. The second bearing 14 is mounted on the hollow rotor shaft 7. The magnet 15 is mounted at the end of the hollow rotor shaft 7. The encoder is mounted between the hollow rotor shaft 7 and the encoder rear end cover 13.

[0038] One end of the front cover 2 is positioned by the positioning port 2b and connected to the housing 6, and the other end is provided with a flange positioning surface 2a.

[0039] The ball nut assembly includes a ball screw 1 and a ball nut 3, which are respectively connected to the hollow rotor shaft 7. The ball screw 1 is connected to the first screw 9 to prevent loosening. The connection is coated with the first glue 1b. The hollow rotor shaft 7 itself is equipped with front and rear bearings on the same axis, which will relatively reduce the positioning error.

[0040] As a preferred technical solution, the ball nut 3 includes a flange portion, a smooth shaft portion 3b, and a threaded portion. The flange portion is connected to the inner ring of the first bearing 4, and the threaded portion is connected to the hollow rotor shaft 7. The connection is coated with a second adhesive 7a.

[0041] The precision hole of the hollow rotor shaft 7 flares out with the outer diameter of the ball nut 3. The internal thread of the hollow rotor shaft 7 is connected to the external thread of the ball nut 3 and fixed with glue. The flange part of the ball nut 3 and the stepped flange of the hollow rotor shaft 7 fix the inner ring of the first bearing 4. The bearing chambers of the front end cover 2 and the housing 6 fix the outer rings of the two first bearings 4. A precision washer 5 is set between the inner ring or the outer ring of the first bearing 4 to eliminate axial clearance.

[0042] The housing 6 has an outer stop positioning circle 6a that mates with the outer circle of the stator 8, and the rear end cover 10 has an end cover positioning circle 10a that mates with the inner hole of the stator 8. The housing 6 has a bearing chamber that mates with two first bearings 4; the rear end cover 10 has a bearing chamber that mates with a second bearing 14, and the end faces of the housing 6 and the rear end cover 10 mate with the end faces of the stator. The electric cylinder also includes a mounting screw, which passes through the through hole of the rear end cover and the through hole of the stator and then connects to the threaded hole of the housing; or the mounting screw passes through the through hole of the encoder rear cover, the through hole of the rear end cover, and the through hole of the stator and then connects to the threaded hole of the housing.

[0043] The ball nut 3 and the hollow rotor shaft 7 are clearance fit. A wave washer 12 is provided between the rear end cover 10 and the hollow rotor shaft 7, and the connection between the magnet 15 and the hollow rotor shaft 7 is coated with a third adhesive 7b.

[0044] The hollow rotor shaft 7 has a flat end for easy installation and locking of the ball nut and rotor. The tail end is connected to the magnet 15 and glue is added. The ball screw 1 has a first flat wire 1a, the ball nut 3 has a second flat wire 3a, and the hollow rotor shaft 7 has a third flat wire for easy product assembly. The tail end of the ball screw 1 has a threaded hole for easy installation of screws to prevent the nut from falling out.

[0045] The assembly process of this utility model is as follows:

[0046] The tail end of the ball screw 1 is connected by a screw. The ball nut pair (ball screw 1 and ball nut 3) passes through the first bearing 4 and is threaded onto the hollow rotor shaft 7. Two first bearings 4 pass through the hollow rotor shaft 7, with a precision shim 5 installed in between. The assembly is positioned by the stepped flange of the hollow rotor shaft 7 and the flange of the ball nut 3. The entire assembly is installed in the bearing chamber of the housing 6, and the front cover 2 is pressed against the outer ring of the first bearing 4 and screwed onto the housing 6.

[0047] The entire front cover assembly is passed through the stator 8 through the end of the hollow rotor shaft 7. The second bearing 14 is installed on the hollow rotor shaft 7, and a protective cover 11 is added. Then the rear cover 10 is assembled. A wave washer 12 is installed in front and positioned by the end cover positioning circle 10a. Long screws are bolted through the rear cover 10, the stator 8, and the housing 6.

[0048] Magnetize the hollow rotor shaft 7, position and press the magnet 15 at the rear end of the hollow rotor shaft 7, and apply glue. The encoder is installed between the hollow rotor shaft 7 and the encoder rear end cover 13. Screws are connected diagonally through the encoder rear cover 13. Two screws pass through the rear end cover 10 and the stator through hole and are connected to the threaded hole of the housing 6.

[0049] Example 2

[0050] like Figure 5-7 As shown, the electric cylinder in this embodiment also includes a guide rail mounting plate 16, a guide rail pair, an L-shaped plate 19, a lock nut 20, and a fixing pin 21. The guide rail pair is mounted on the guide rail mounting plate 16 and includes a guide rail 17 and a slider 18. The slider 18 moves on the guide rail 17. The guide rail mounting plate 16 is mounted on the housing 6 and positioned by the fixing pin 21, and then connected by screws. The end face of the ball screw 1 is connected to the L-shaped plate 19 and connected by the lock nut 20. The rest is the same as in Embodiment 1.

[0051] The above description is merely a specific embodiment of this utility model, but the protection scope of this utility model is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this utility model, and these modifications or substitutions should all be covered within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. A miniature electric cylinder, characterized in that, The electric cylinder includes a ball nut assembly, a front end cover (2), a first bearing (4), a housing (6), a hollow rotor shaft (7), a stator (8), a rear end cover (10), an encoder, an encoder rear end cover (13), a second bearing (14), and a magnet (15). The ball nut assembly passes through the first bearing (4) and connects to the hollow rotor shaft (7). The front end cover (2) presses against the outer ring of the first bearing (4) and connects to one end of the housing (6). The other end of the housing (6), the stator (8), and the rear end cover (10) are connected in sequence. The second bearing (14) is mounted on the hollow rotor shaft (7). The magnet (15) is mounted at the end of the hollow rotor shaft (7). The encoder is mounted between the hollow rotor shaft (7) and the encoder rear end cover (13).

2. The miniature electric cylinder according to claim 1, characterized in that, The ball nut assembly includes a ball screw (1) and a ball nut (3) respectively connected to the hollow rotor shaft (7). The ball screw (1) is connected to the first screw (9), and the connection is coated with the first glue (1b).

3. A miniature electric cylinder according to claim 2, characterized in that, The ball nut (3) includes a flange portion, a nut shaft portion (3b) and a threaded portion. The flange portion is connected to the inner ring of the first bearing (4), and the threaded portion is connected to the hollow rotor shaft (7). The connection is coated with a second adhesive (7a).

4. The miniature electric cylinder according to claim 1, characterized in that, One end of the front cover (2) is positioned by the positioning port (2b) and connected to the housing (6), and the other end is provided with a flange positioning surface (2a).

5. A miniature electric cylinder according to claim 1, characterized in that, There are two first bearings (4), and a precision washer (5) is provided between the two first bearings (4).

6. A miniature electric cylinder according to claim 1, characterized in that, The housing (6) is provided with an outer stop positioning circle (6a) that mates with the outer circle of the stator (8), and the rear end cover (10) is provided with an end cover positioning circle (10a) that mates with the inner hole of the stator (8).

7. A miniature electric cylinder according to claim 1, characterized in that, A wave-shaped washer (12) is provided between the rear end cover (10) and the hollow rotor shaft (7), and a third adhesive (7b) is applied to the connection between the magnet (15) and the hollow rotor shaft (7).

8. A miniature electric cylinder according to claim 2, characterized in that, The ball screw (1) is provided with a first flat wire (1a), the ball nut (3) is provided with a second flat wire (3a), and the hollow rotor shaft (7) is provided with a third flat wire at its end.

9. A miniature electric cylinder according to claim 1, characterized in that, The electric cylinder also includes a mounting screw, which passes through the rear cover through hole and the stator through hole and is connected to the housing threaded hole; or the mounting screw passes through the encoder rear cover through hole, the rear cover through hole and the stator through hole and is connected to the housing threaded hole.

10. A miniature electric cylinder according to claim 2, characterized in that, The electric cylinder also includes a guide rail mounting plate (16), a guide rail pair, an L-shaped plate (19), a lock nut (20), and a fixing pin (21). The guide rail pair is mounted on the guide rail mounting plate (16) and includes a guide rail (17) and a slider (18). The slider (18) moves on the guide rail (17). The guide rail mounting plate (16) is mounted on the housing (6) and positioned by the fixing pin (21), and then connected by screws. The end face of the ball screw (1) is connected to the L-shaped plate (19) and connected by the lock nut (20).

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