KR100206507B1 - Electric actuator - Google Patents

Abstract

The electric actuator is a long base 12, a sliding table which is longitudinally displaceable along the power unit 180 and the encoder device 20 and the base 12 fixed on both ends of the base 12 in a corresponding relationship with each other. 52, the ball screw 16 for transmitting rotational power from the power unit 18 to the sliding table 52 and the base 12 for guiding the sliding table 52 in the longitudinal direction along the base 12. It has one pair of guide lands 32a and 32b.

Description

Electric actuator

1 is an exploded perspective view of an electric actuator according to a first embodiment of the present invention.

2 is a cross-sectional view taken along the line II-II of FIG.

3 is an exploded perspective view of the electric actuator according to the second embodiment of the present invention.

4 is an exploded perspective view of the electric actuator shown in FIG.

5 is a cross-sectional view taken along the line V-V of FIG.

6 is a front view of the motor housing of the electric actuator shown in FIG.

7 is a longitudinal sectional view of the drive unit and encoder of the electric actuator shown in FIG.

8 is a partial cross-sectional view of a drive unit of the electric actuator shown in FIG.

FIG. 9 is a cross-sectional view taken along the line IX-IX of FIG.

FIG. 10 is a partial cross-sectional view of the encoder of the electric actuator shown in FIG.

[Background of invention]

[Field of Invention]

The present invention relates to an electric actuator having a sliding table that is displaceable according to the operation of a rotary power unit.

[Description of Related Technologies]

Electric actuators have been used as a means of conveying workpieces. One electric actuator of the conventional design has a long frame, an electric motor disposed in the frame, a ball screw which converts the rotational motion generated by the electric motor into a linear motion and transmits it to another member, and is fixedly mounted on the upper surface of the frame. Basically, it consists of a pair of parallel guide rails and a sliding table which is guided by guide rails and is longitudinally displaceable along the frame by a ball screw.

The ball screw is rotatably supported by a bearing at one end thereof. The electric motor has a motor shaft coaxially connected at the other end of the ballscrew by a coupling. The encoder is located near the electric motor to detect the angular displacement, rotation speed, etc. of the electric motor.

Since the frame of a conventional electric actuator is made of aluminum, its rigidity is relatively weak. Thus, the linearity and parallelism precision of the sliding table will depend substantially on the guide rail made of stainless steel with high rigidity. Conventional electric actuators have a height equal to the sum of the height of the frame and the height of the guide rail fixedly mounted on the upper surface of the frame. It is not possible to maintain the high level of rigidity required while regulating the height of the electric actuator.

Since it is a separate part of the frame and the guide rail, the conventional electric actuator is made of a relatively large number of parts, it is assembled through a relatively large number of steps, the manufacturing cost is expensive.

Another problem with conventional electric actuators is that the ballscrews and motor shafts must be coaxially connected to each other by coupling when assembled, and the ballscrews need to be arranged along the axis of the frame, so that precision in complex processes To be positioned.

[Overview of invention]

It is an overall object of the present invention to provide an electric actuator that can be manufactured inexpensively with a regulated height while maintaining the high level of rigidity required.

It is an object of the present invention to provide an electric actuator which can be easily assembled in place without the need for the ballscrew to be positioned.

These and other objects, features, and advantages of the present invention will become apparent from the following description set forth in connection with the accompanying drawings which illustrate preferred embodiments of the invention.

Detailed Description of the Preferred Embodiments

As shown in FIG. 1, the electric actuator 10 according to the first embodiment of the present invention is a ball screw which is supported in a longitudinal direction by an elongated base 12 and an elongated groove 14 formed on an upper surface of the base 12. (16), a power unit 18 mounted at one longitudinal end of the base 12 to rotate the ball screw 16 about its own axis, and an encoder device 20 mounted at the other longitudinal end of the base. And a cover 22 covering the recess 14 in the base 12.

The cover 22 is attached to an upper cover 24 for closing the upper surface of the base 12 and a pair of side surfaces respectively attached to opposite ends of the upper cover 24 in the longitudinal direction to close each of the longitudinal ends of the base 12. It consists of covers 26 and 27. The side cover 26 has a window 28 formed therein for passing a conductor (not shown) electrically connected to the power unit 18 and the encoder device 20. The electric actuator 10 is guided by two pairs of bearing members (described later) each positioned on each side of the ball screw 16 in correspondence with each other and corresponding to the rotation of the ball screw 16. It also has a sliding mechanism 30 which is displaceable in the longitudinal direction along 12.

The base 12 has an integrated structure made of steel (SPC) or the like by drawing, and has high rigidity. The base 12 has a C-shaped channel cross section and has a flat cross extending between the pair of longitudinal guide lands 32a and 32b and the longitudinal guide lands 32a and 32b spaced apart from each other in the transverse direction of the base 12. Plate 34 is included. These guide lands 32a and 32b have opposing inner wall surfaces, each having grooves 36a and 36b of substantially V-shaped cross section formed in the longitudinal direction therein. The bearing member (described later) rolls in the grooves 36a and 36b.

The power unit 18 projects away from each other in the transverse direction of the base 12 and has a motor housing 40 having a pair of arms 38a and 38b fixed to the upper surfaces of the guide lands 32a and 32b, respectively. It consists of the motor unit 44 fitted in the through-hole 42 formed axially in the housing 40. As shown in FIG. The motor housing 40 is preferably injection molded from aluminum. The motor unit 44 has a substantially cylindrical casing that houses the rotor and stator (not shown) that make up the electric motor. The electric motor is coaxially integrated at the end of the ball screw 16 without the need for coupling and has a motor shaft on which the rotor is fixedly mounted.

The encoder device 20 is projected apart from each other in the transverse direction of the base 12, the encoder housing 46, the encoder housing having a pair of arms (38a, 38b) fixed to each of the upper surface of the guide land (32a, 32b). It consists of an encoder unit 50 fitted into the through hole 48 formed in axial line at 46. The encoder housing 46 is preferably injection molded from aluminum. Encoder unit 50 has a substantially cylindrical casing that accommodates a rotary encoder (not shown) that detects angular displacement, rotational speed, etc. of the electric motor and other ball screws 16. The rotary encoder has an encoder shaft coaxially integrally connected to the other end of the ball screw 16 without the need for coupling. The holes 42 and 48 formed in the motor housing 40 and the encoder housing 46 each have the same diameter.

The motor unit 44 and the encoder unit 50 are fitted into respective holes 42 and 48 formed in the motor housing 40 and the encoder housing 46, and the motor housing 40 and the encoder housing 46 are fitted. When fixed to each longitudinal end of the base 12 via arms 38a and 38b, the motor shaft of the power unit 18, the ball screw 16 and the encoder shaft of the encoder device 20 are coaxially aligned with each other. It is. Thus, the motor unit 44 and the encoder unit 50 can be easily assembled on the base 12 without the alignment work for the motor shaft and the ball screw 16.

The sliding mechanism 30 includes a sliding terrier 52 for supporting the workpiece through an attachment hole (not shown) formed in the upper surface. The sliding table 52 extends laterally between the pair of sliding blocks 54a and 54b and the sliding blocks 54a and 54b which are slidable along and above each guide land 32a and 32b of the base 12. The holder block 56 is integrally connected to the sliding block. The holder block 56 has an opening 58 formed in the center extending in the axial direction of the ball screw. This opening 58 retains therein a cylindrical bearing block 60 threaded to the ball screw 16.

As shown in FIG. 2, the sliding blocks 54a and 54b are spaced from each other and correspond to each other and each of the fixed and eccentric bearing members 62 and 64 pair fixed to the sliding blocks 54a and 54b. I support it. These fixed and eccentric bearing members 62 and 64 are guide wheels 68 and guide wheels 68, respectively, having inclined outer circumferential surfaces 66 rolling in the grooves 36a and 36b in the guide lands 32a and 32b. Respective bushings 71a and 71b rotatably supported by this ball bearing 70, respective bolts 72 for securing the bushings 71a and 71b to the sliding blocks 54a and 54b, and respective bolts, respectively. Each nut 74 screwed to 72.

In each of the fixed bearing members 62, the bolts 72 are aligned in line with the buoy 71a. In each of the eccentric bearing members 62, the bolt 72 has an axis A maintained without axial alignment with the axis B of the bushing 71b. Therefore, when the bolt 72 rotates about the axis A, the bushing 71b rotates about its own axis B so that the guide wheel 68 makes a rolling contact with the groove 36b. Adjust Since the guide wheels 68 of the fixed and eccentric bearing members 62 and 64 are located next to the opposite inner wall surfaces of the guide lands 32a and 32b, no excessive restriction is given to the height of the guide wheels 68. .

The electric actuator 10 is assembled as follows.

The motor unit 44 and the encoder unit 50 having a cylindrical shape are fitted into the through holes 42 and 48 formed in the motor housing 40 and the encoder housing 46, respectively. Then, screws (not shown) are screwed into the screw holes formed in the arms 38a and 38b to fix the motor housing 40 and the encoder housing 46 to the upper surface of the base 12 at both ends thereof in the longitudinal direction. .

The power unit 18, the ball screw 16 and the encoder device 20 are coaxially aligned with each other by simply fixing the motor housing 40 and the encoder housing 46 to the base 12 as described above. Therefore, the power unit 18, the ball screw 16 and the encoder device 20 can be easily assembled by making coaxial alignment since it is not necessary to adjust them for coaxial alignment with each other.

The operation of the electric actuator 10 will be described below.

The power supply electrically connected to the electric motor of the power unit 18 is turned on to excite the electric motor. The ball screw 16 is rotated about its axis such that the bearing block 60 displaces the sliding table 52 in the longitudinal direction along the ball screw 16 and thus the base 12. As a result, the slide table 52 can move the workpiece along the electric actuator 10 by a desired distance.

Due to the guide lands 32a and 32b integrally formed with the base 12 opposite to each other, the electric actuator 10 has a height smaller than that of a conventional electric actuator in which the frame and the guide rail are separated from each other and assembled together. Thus, the electric actuator 10 is relatively small and lightweight, consists of a relatively small number of parts, and can be manufactured relatively inexpensively.

The electric actuator 80 according to the second embodiment of the present invention will be described below with reference to FIGS. 3 to 10. Parts shown in FIGS. 3 to 10 which are the same as shown in FIGS. 1 and 2 are denoted by the same reference numerals and will not be described in detail below.

The electric actuator 80 according to the second embodiment has an elongated guide land 86 formed integrally with one longitudinal edge of the flat plate 84 of the elongated base 82 and extending along this longitudinal edge. A long guide rail 88, separated from the base 82, is fixedly mounted on the ground in the other opposite longitudinal direction of the flat plate 84 and extends along this longitudinal edge, and the guide rail 88 is a guide land. It differs from the electric actuator 10 according to the first embodiment in that it is substantially the same shape as (86).

The electric actuator 80 according to the second embodiment of the present invention has a base 82 in order to rotate an elongated base 82, a ball screw 16 supported in the longitudinal direction on an upper surface of the base 82, and a ball screw 16 about its axis. A power unit 90 mounted at the longitudinal end of the 82, an encoder device 92 mounted at the other longitudinal end of the base 82, and a cover 22 covering the upper surface of the base 82. . The electric actuator 80 is guided by two pairs of four bearing blocks 93 positioned correspondingly to each other on each side of the ball screw 16 and corresponding to the rotation of the ball screw 16. It also has a sliding mechanism 94 that is longitudinally displaceable along 82. The bearing blocks 93 each have a ball bearing (not shown) which circulates by moving and circulating in and along the guide groove 96 (described later).

Since the base 82 is a single structure made of steel (SCP) or the like by drawing, it has high rigidity. The guide land 86 protruding upward is integrally formed with one longitudinal edge of the flat plate 84. The guide rail 88 is fixed to the upper surface of the other longitudinal edge of the flat plate 84 laterally spaced apart from the guide land 86 (see FIG. 4). Guide land 86 and guide rail 88 have opposing inner wall surfaces with respective guide grooves 96 formed in the longitudinal direction. The bearing block 93 is movably mounted on the guide land 86 and the guide rail 88 so that the ball bearings of the bearing block 93 roll in the guide groove 96. The bearing blocks 93 have the same shape as each other. The guide rail 88 preferably has an automatic alignment function such that the corresponding bearing block 93 is kept in alignment with the guide rail 88. This automatic alignment function may allow the attachment surface of the guide rail 88 to be machined with a relatively large tolerance.

The power unit 90 protrudes away from each other in the transverse direction of the base 82 and has a motor housing 100 having a pair of arms 98a and 98b fixed to respective upper surfaces of the guide land 86 and the guide rail 88. ) And a motor unit 104 fitted into an opening 102 formed axially in the motor housing 100. The motor housing 100 preferably has a fitting slot 106 (see FIG. 4) which is injection molded from aluminum and formed on the curved inner wall surface of the opening 102. The base 82 has a rectangular recess 108 formed in the upper surface of its longitudinal end on which the power unit 90 is mounted. The motor housing 110 has a lower surface 110 (see FIG. 5) fitted to the recess 108 and is fixed to the base 82 (see FIG. 9).

As shown in FIGS. 7 to 9, the motor unit 104 includes a casing 112 held in the opening 102, a bearing 116 disposed in the casing 112, and one end of the ball screw 16. The motor shaft 14, the rotor 118 fixedly mounted on the motor shaft 114, and the casing 112 integrally and coaxially jointly rotatably supported by the bearing 116. It has a laminated stator 120 fixedly mounted on the wall. The stator 120 and the rotor 118 together constitute an electric motor. The ring damper 122 is fitted to one end of the casing 112. A wave washer 124 is disposed in the casing 112 and held opposite one end of the bearing 116.

As shown in FIG. 4, the encoder device 92 is projected apart from each other in the lateral direction of the base 82 and is a pair of arms 98a fixed to the upper surfaces of the guide lands 86 and the guide rails 88, respectively. And an encoder unit 130 fitted into an opening 128 formed in the encoder housing 126. The encoder housing 126 is preferably injection molded from aluminum and has a fitting slot 106 formed on the curved inner wall surface of the opening 128. The encoder housing 126 has a base (11) in a state where the lower surface 110 of the encoder housing 126 is accommodated in a rectangular recess 108 formed in the upper surface of the longitudinal end of the base 82 on which the encoder device 92 is mounted. 82) is positioned in position.

As shown in FIGS. 7 and 10, the encoder unit 130 retains the bearing 132, the bearing 132, which rotatably supports the ball screw 16, and the corner slot fitting slot 106. A cylindrical holder block 134 (see FIG. 10), positioned in position and fitted to the holder block 134 and supporting a ring-shaped damper 136 at its far end. Rotary encoder 142 having a cover block 138 and an encoder shaft 140 integrally formed with the other end of the ball screw 16 for detecting the angular displacement, rotational speed, etc. of the electric motor, thus the ball screw. It consists of.

The motor housing 100 and the encoder housing 126 have the same shape, and the openings 102 and 128 formed in each of them have the same diameter (see FIG. 6). Motor unit 104 and encoder unit 130 are fitted into respective openings 102 and 128, and motor housing 100 and encoder housing 126 are fitted into respective recesses 108 to arms 98a and 98b. When positioned at a fixed end of each of the longitudinal ends of the base 82, the motor shaft, the ball screw 16 and the encoder device 92 of the power unit 90 are coaxially aligned with each other. 90 and the encoder device 92 can be easily assembled on the base 82 without the alignment of the motor shaft and the ball screw 16.

The sliding mechanism 94 includes a sliding table 144 for supporting a work piece through an attachment hole (not shown) formed in the upper surface of the sliding table 144. The sliding table 144 is integrally joined to a pair of sliding blocks 146a and 146b and sliding blocks 146a and 146b which are slidable above and along the guide lands 86 and the guide rails 88, respectively. It consists of a holder block 148 extending laterally between the sliding blocks. The sliding blocks 146a and 146b are mounted to each pair of bearing blocks 93. The holder block 148 has an opening 150 formed in the center extending in the axial direction of the ball screw 16. The opening 150 holds the cylindrical bearing block 152 therein with a flange 154 screwed to the ball screw 16 and fixed to one end of the holder block 148.

Other structural details, operation, and advantages of the electric actuator 80 according to the second embodiment are the same as those of the electric actuator 10 according to the first embodiment and will not be described in detail below.

Electric actuators 10 and 80 provide the following advantages; The electric actuators 10 and 80 are relatively small and light because they regulate their height while maintaining high strength.

Since at least one of the guide lands is integrally formed with the base, the electric actuators 10 and 80 are made up of a relatively small number of parts and assembled in a relatively small number of steps, thus making them relatively inexpensive.

Since no special alignment is required to align the ball screw 16 coaxially with the power units 18 and 90 and the encoder devices 20 and 92, the ball screw 16 can be easily positioned and assembled.

Although the present invention has been described in detail with reference to the preferred embodiments thereof, it is apparent that various changes and modifications may be made without departing from the scope of the appended claims.

Claims (8)

A base 12 and 82 formed long along a longitudinal direction, rotational power means 18 and 90 fixedly installed at one end of the base, and fixedly opposed to the other end of the base, A sliding mechanism (30,94) having a detection means (20,92) for detecting an amount of rotation, a sliding table (52,144) displaced along the longitudinal direction of the base under the driving action of the rotary power means, and the rotary power means A driving force transmitting means 16 for transmitting a driving force of the sliding table to the sliding table, and guide means 32a, 32b, 86 for guiding the sliding tables 52, 144 along the longitudinal direction of the base, the guide means being a base; Integrally formed along the longitudinal direction of the base, and protruding upwardly toward the side portion substantially perpendicular to the longitudinal direction of the base on the plate, and the bases 12 and 82 and the guide means 32a, 32b and 86. Formed by The inner actuator is an electric actuator, characterized in that the bearing member which is displaced along the long groove formed on the inner wall surface of the guide means. The guide means is composed of a pair of guide lands (32a, 32b) extending in the longitudinal direction along the base (12) and laterally spaced apart from each other, the guide lands (32a, 32b) An electric actuator, characterized in that it is integrated with the base (12). 2. The guide means according to claim 1, wherein the guide means comprises a guide land 86 extending longitudinally along the base 12 and integral with the base 12, wherein the guide means is longitudinally along the base 12. It further comprises a guide rail 88 which is spaced apart from the base 12 is fixed to the base 12, the guide land 86 and the guide rail 88 are laterally spaced apart from each other An electric actuator, characterized in that. 2. The rotary power means (18,90) is fitted to the motor housing (40,100) and the openings (42,102), which are mounted on the base (12,82) and have openings (42,102) formed therein. Encoder housings 46 and 126 and the openings (36, 126), which are composed of customized motor units (44, 104), the detection means (20, 92) mounted on the base (12, 82) and having openings (48, 128) formed therein. And the encoder units 50 and 130 fitted to the 48 and 128, wherein the motor housings 40 and 100 and the encoder housings 46 and 126 have the same shape, and the openings 42 and 102 formed in the motor housings 40 and 106, respectively. And the openings (48,128) formed in the encoder housing (46,126) are of equal size to each other. 3. The guide lands 32a and 32b have respective grooves 36a and 36b defined on their respective opposite inner wall surfaces, and slide along the elongated base 12 in the longitudinal direction. An electric actuator further comprising at least one pair of bearing members 62 and 64 mounted on the sliding table 52 to guide the table 52 and engaged with the grooves 36a and 36b respectively. . 6. The bearing member according to claim 5, wherein the bearing member includes a fixed bearing member (62) fixedly mounted on the sliding mechanism (30) and an eccentric bearing member (64) adjustablely mounted on the sliding mechanism (30). An electric actuator, characterized in that. The method of claim 1, wherein the rotary power means comprises a motor shaft 114, the detection means comprises an encoder shaft 140, the power transmission means is the motor shaft 114 and the encoder shaft ( An electric actuator comprising: a ball screw (16) integral with the ball screw (140), wherein the ball screw (16), the motor shaft (114) and the encoder shaft (140) are coaxially aligned with each other. The sliding table (52,144) is a pair of sliding blocks (54a, 54b, 146a, 146b) and the sliding blocks (54a, 54b, 146a) slidable along the guide means (32a, 32b, 86). And 146b) a holder block (56, 148) extending laterally and integrally joined to the sliding block.