JPH11351348A - Electric actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an actuator capable of highly precise carrying or horizontal carrying and excellent in dust prevention. SOLUTION: This electric actuator 1 is provided with an actuator body 2, a motor 12 and a movable body M1. A screw means 18, which is a part of a feed screw mechanism, is housed rotatably within the actuator body 2. The movable body M1 comprises a plate-like feeding means 21, a working plate 22 and a guide rod 23. The plate-like feeding means 21 is reciprocatingly housed within the actuator body 2. The guide rod 23 penetrate through the actuator body 2 to connect the plate-like feeing means 21 integrally movably to the working plate 22. Since the screw means 18 is inserted through the plate- like feeding means 21, the rotating motion, when a motor 12 is rotated, is covered into a linear motion by the feed screw mechanism. At that time, the linear movement of the movable body M1 is guided by a guide mechanism.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an electric actuator.

[0002]

2. Description of the Related Art Conventionally, various electric actuators (electric cylinders) are known as devices for converting a rotary motion into a linear motion.

[0003] The actuator body constituting such an electric actuator generally has a tubular shape.
A motor is attached to one end opening of the actuator body. The output shaft of the motor is arranged in a central hole of the actuator body. The output shaft of the motor and the feed screw means are integrally rotatably connected by a coupling. A cylindrical member is housed in the central hole of the actuator body so as to be able to protrude and retract. At the front end of the tubular member, a work to be transferred can be attached.
A feed nut member is fixed to the rear end opening of the tubular member. The feed nut member is screwed with a feed screw means, and these two members constitute one mechanical feed screw mechanism for converting a rotary motion into a linear motion. On the inner peripheral surface of the actuator main body, a long groove for detent extending along the axial direction of the actuator main body is formed. An engagement projection for preventing rotation is also provided on the outer peripheral surface of the rear end portion of the cylindrical member, and the engagement projection is slidably disposed in the long groove. In addition, as a technique of the same kind, there is a technique disclosed in, for example, Japanese Patent Publication No. 51-24663.

When the motor is driven to rotate in the prior art, the cylindrical member moves linearly by the action of the feed screw mechanism. Also, when the tubular member moves,
The rotation of the cylindrical member is prevented by engaging the engagement protrusion with the long groove.

[0005]

However, the rotation preventing mechanism of the prior art is a simple one in which the engaging projection and the long groove are combined, so that the rotation of the moving body cannot be reliably prevented. Accordingly, there is a problem in that the work is easily rattled, and as a result, it is difficult to carry out the transfer with high accuracy.
Further, there is a problem that the ability to receive a biased load generated when the moving body is at the most advanced position is insufficient, so that it is not suitable for horizontally transporting a heavy work. As described above, conventionally, it is necessary to use some kind of guide mechanism separately outside the apparatus, and this has been a factor that causes the overall size and weight to increase.

Further, when this type of device is used in an environment with a large amount of dust, for example, the dust tends to adhere to the feed screw mechanism, so that a failure is likely to occur. Have been. In addition, considering use in a clean environment, the device is also required to have low dust emission.

The present invention has been made in view of the above circumstances, and a first object of the present invention is to provide an electric actuator which can perform high-precision conveyance and horizontal conveyance, and is excellent in dustproofness. is there.

A second object of the present invention is to provide an electric actuator having low dust generation and long life.

[0009]

In order to solve the above-mentioned problems, according to the present invention, the rotational movement of a motor attached to an actuator body is controlled by a feed unit which is rotationally driven by the motor. By converting the movement into a linear motion by a feed screw mechanism comprising a screw means inserted through the feed means, the moving body having a part of the feed means is moved linearly along the axial direction of the screw means. In the electric actuator, screw means rotatably housed in the actuator body, and feed means housed reciprocally in the actuator body,
A movable body provided outside the actuator main body, and a guide body disposed so as to penetrate the actuator main body and including a guide rod for integrally connecting the feed means and the active plate with each other; A guide mechanism for guiding the moving body in a straight line, wherein the screw means is inserted through the feed means at a position different from the guide rod connecting position. I do.

According to a second aspect of the present invention, in the first aspect, the feed screw mechanism includes a feed unit having a thread groove on an inner peripheral surface of the through hole, and a feed unit having a screw groove on an outer peripheral surface. The mechanical feed screw mechanism includes a screw means that is inserted in a state of being screwed into the through hole.

According to a third aspect of the present invention, in the first aspect, the feed screw mechanism includes a feed means having a magnetized band spirally magnetized on the inner peripheral surface of the through hole, and a spiral means on the outer peripheral surface. The magnetic feed screw mechanism has a magnetized band magnetized in a shape and a screw means inserted through the through hole of the feed means in a non-contact state.

The invention described in claim 4 is the first to third aspects of the present invention.
In any one of the above items, the feeding means having the oval cross section is accommodated in the accommodation hole having the oval cross section of the actuator body having the flat shape.

According to a fifth aspect of the present invention, in the fourth aspect, the guide rod is provided as a pair with the screw means interposed therebetween. The invention according to claim 6 is the invention according to claim 1.
6. The guide rod insertion hole according to any one of 1 to 5, wherein the guide mechanism is formed so as to extend along a longitudinal direction of the actuator body, and has a contact-type bearing portion therein, and the contact-type bearing. And the guide rod slidably inserted through the portion.

[0014] The invention according to claim 7 is the invention according to claims 1 to 5.
In any one of the above, the guide mechanism is a linear guide including a long guide rail and a guide block slidably engaged with the guide rail, and one of the guide rail and the guide block. Is attached to the moving body side, and the other is attached to the actuator body side.

The invention described in claim 8 is the invention according to claims 1 to 7
In any one of the above, the end of the screw means is rotatably supported by a bearing provided in the actuator body.

The invention according to claim 9 is the invention according to claims 1 to 8
In any one of the above, a sensor holding groove extending along a longitudinal direction of the actuator body is formed on an outer peripheral surface of the actuator body, and a permanent magnet is provided at a position corresponding to the sensor holding groove on an outer peripheral portion of the feeding means. It has been attached.

Hereinafter, the "action" of the present invention will be described. According to the first to ninth aspects of the present invention, as the moving body moves straight while being guided by the guide mechanism, the rotation of the moving body is reliably prevented, and the work is less likely to rattle.
Therefore, high-precision conveyance and horizontal conveyance that cannot be achieved by the conventional simple rotation preventing mechanism can be performed. Further, the feed means and the screw means, which are components of the feed screw mechanism, are both housed in the actuator body and are isolated from the external environment of the apparatus. Therefore, even when the device is used in an environment with a lot of dust, there is no fear that dust adheres to the feed screw mechanism, and excellent dustproofness can be secured at the portion.

According to the second aspect of the present invention, when the screw means is rotated in a predetermined direction in a state where the screw means is screwed to the feed means, the feed means is moved in the axial direction of the screw means by the action of both screw grooves. Is sent mechanically along. as a result,
The rotational movement of the motor is converted to a linear movement, and the moving body moves linearly with the feeding means. Further, since such mechanical feed screw mechanisms are often inexpensive, they are suitable for reducing the cost of the entire apparatus.

According to the third aspect of the present invention, when the screw means is rotated in a predetermined direction in a state where the screw means is inserted into the feed means in a non-contact manner, the magnetic repulsive force or the magnetic repulsive force between the magnetized bands of the two. The suction means causes the feed means to be magnetically fed along the axial direction of the screw means. As a result, the rotational motion of the motor is converted into a linear motion, and the moving body moves linearly together with the feeding means. Further, in such a magnetic feed screw mechanism, since the feed means and the screw means do not come into mechanical contact with each other, there is almost no abrasion of the relevant portion unlike the mechanical feed screw mechanism. Therefore, a device with low dust generation and a long life can be obtained. Moreover, since the structure does not require the supply of the lubricant to the contact portion, it is possible to provide a device having excellent maintainability.

According to the fourth aspect of the present invention, since the actuator body and the feeding means are formed into the above-mentioned predetermined shapes to form a thin electric actuator, the size and weight of the entire apparatus can be reduced.

According to the fifth aspect of the present invention, since the straight running guide and the detent are provided at two places separated from each other, more reliable straight running guide and the detent can be achieved.

According to the invention described in claim 6, the sliding movement between the guide rod inserted into the guide rod insertion hole and the bearing portion allows the moving body to move straight while being guided with high precision, and at this time, the moving body Is prevented. Also,
With such a mechanism, the structure can be relatively simple, which is suitable for cost reduction.

According to the seventh aspect of the present invention, the sliding movement in the engaged state between the guide rail and the guide block allows the moving body to move straight while being guided with high precision, and at that time, to prevent the moving body from rotating. Is achieved. In addition, since such a mechanism can be installed on the outer surface of the apparatus, there is an advantage that the size is hardly restricted. That is, it is permissible to use a large linear guide without increasing the size of the actuator body or the moving body.

According to the eighth aspect of the present invention, since the screw means is prevented from rattling by being supported by the bearing portion, the screw means rotates smoothly. Therefore, dust generation from the feed screw mechanism can be more reliably prevented.

According to the ninth aspect of the present invention, if a sensor responsive to magnetism, for example, is held at a predetermined position in the sensor holding groove, when the feed means comes close to the sensor, the sensor becomes a permanent magnet. Turns on or off in response to the magnetism of As a result, the moving position of the moving body can be detected in a non-contact manner.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] An electric actuator 1 according to one embodiment of the present invention will now be described with reference to FIG.
3 will be described in detail.

The actuator main body 2 constituting the electric actuator 1 of this embodiment comprises a tube 3 as a tubular member and a pair of covers 4 and 5 for closing both ends of the tube 3. The tube 3 has a flat shape and an equal cross-sectional shape, and has a receiving hole 6 having a round cross-sectional shape therein. The tube 3 is manufactured by extrusion or pultruding using metal as a molding material. In FIG. 2, the rod cover 4 that closes the left end surface of the tube 3 is formed thicker than the head cover 5 that closes the right end surface of the tube 3 in the present embodiment.

As shown in FIG. 1 to FIG.
Are formed with two sensor holding grooves 7 extending along the longitudinal direction of the actuator body 2. These sensor holding grooves 7 have an equal cross-sectional shape and a substantially inverted T-shaped cross-section, and a magnetic sensor 8 is held therein so that the position can be changed. For example, these magnetic sensors 8 are provided corresponding to the end position of the stroke.

A through hole 9 is provided at the center of the head cover 5 and a fixing sleeve 10 is provided in the through hole 9.
Is inserted. A motor 12 is mounted on the outer surface of the head cover 5 at a position corresponding to the through hole 9. The output shaft 11 of the motor 12 is located at the center of the hole of the fixing sleeve 10. The motor 12
For example, a motor with a brake mechanism or the like may be selected. This ensures that the rotational position of the motor 12 is maintained even during a power failure, and
Can be prevented from being displaced.

A proximal bearing 16 is provided at the inner opening of the fixing sleeve 10, and a distal bearing 17 is provided at the center of the inner surface of the rod cover 4. The base end portion of a screw means 18 constituting a mechanical feed screw mechanism is rotatably supported by the base end bearing portion 16.
On the other hand, the distal end portion of the screw means 18 is rotatably supported by the distal end bearing portion 17. These bearing portions 16, 17 support loads in both thrust and radial directions. The screw means 18 is completely accommodated inside the actuator main body 2 in a state of extending along the longitudinal direction of the actuator main body 2. Further, the center axis of the output shaft 11 and the center axis of the screw means 18 are arranged on the same line.

The proximal end of the screw means 18 that has passed through the proximal bearing section 16 and has reached the inside of the fixing sleeve 10 is connected to the motor 12 by a coupling 19 as a connecting means.
Is connected to the distal end side of the output shaft 11. Therefore, the output shaft 11 and the screw means 18 can rotate integrally.

As shown in FIG. 2, in the screw means 18 of this embodiment, the region between the base end and the front end has a large diameter, and the entire outer peripheral surface of the region has a predetermined pitch. A thread groove is formed. As a material for forming the screw means 18, a hard metal such as stainless steel is used. If the screw means 18 is made of resin to make itself light, it is possible to reduce the weight of the entire apparatus.

This electric actuator 1 has a rotary feed plate 21 as feed means, a work mounting plate 22 as an action plate, and a guide rod 23 having a circular cross section.
Is provided.

As shown in FIG. 3, the rotary feed plate 21 according to the present embodiment is a metal plate member having a round cross section and is capable of reciprocating within the receiving hole 6 of the tube 3. Is housed. If the rotary feed plate 21 is made of resin, the weight of the rotary feed plate 21 itself can be reduced, and the weight of the entire apparatus can be reduced. As a material for forming the rotary feed plate 21, a polyimide (PI) resin, an oil-containing polyacetal (POM) resin, a polyetheretherketone (PEEK) resin, a polyphenylene sulfide (PPS) resin, or the like is preferable. In particular, it is preferable to select a polyimide resin excellent in compatibility with stainless steel.

A through hole 24 is formed at the center of the rotary feed plate 21, and a screw groove of the same pitch as the screw groove of the screw means 18 is formed on the inner peripheral surface of the through hole 24. The screw means 18 is inserted into the through hole 24 in a screwed state. As a result, the screw means 18 and the rotary feed plate 21 constitute one mechanical feed screw mechanism.

The rotation feed plate 21 has a rod connection hole 25.
It has. There are two rod connection holes 25, which are provided in a pair and separated from each other with the through hole 24 interposed therebetween. And a pair of guide rods 23
Are inserted through a pair of rod connection holes 25, respectively. In this state, the substrate portion of the guide rod 23 is fixed to the rotary feed plate 21 by a nut 26 so as to be integrally movable. It can also be grasped that the screw means 18 is inserted at a position different from the guide rod connection position on the rotary feed plate 21. Note that the pair of guide rods 23 and the screw means 18 are in a parallel relationship.

As shown in FIG. 2, guide rod insertion holes 27 each having a circular cross section are formed at two separated positions in the rod cover 4. These guide rod insertion holes 27 are both formed so as to extend along the longitudinal direction of the actuator main body 2 (that is, the axial direction of the screw means 18). A ball bearing 28 as a contact bearing is provided on the inner peripheral surface of both guide rod insertion holes 27. The ball bearing 28 is composed of a plurality of balls (not shown) and rolling paths for holding the balls in a rolling manner. A guide rod 23 is slidably inserted into each of the two ball bearings 28. In this case, the ball slides on the outer peripheral surface of the guide rod 23 while rolling. That is, the high-precision guide mechanism according to the present embodiment includes a pair of guide rod insertion holes 27 having ball bearings 28 and a pair of guide rods 23.

The distal end of the guide rod 23 penetrates through the guide rod insertion hole 27 and projects outside the actuator body 2. A work mounting plate 22 having a rectangular shape is connected to a distal end portion of the guide rod 23 by bolts 31 so as to be integrally movable. The front end surface of the work mounting plate 22 serves as a work mounting surface for mounting a work (not shown). Therefore, bolt holes (not shown) are formed at a plurality of locations on the plate 22.

In this embodiment, the rotary feed plate 21
Work mounting plate 22, a pair of guide rods 2
3, one moving body M by the nut 26 and the bolt 31
1 is configured.

As shown in FIGS. 2 and 3, a magnet mounting recess is formed at a position corresponding to the sensor holding groove 7 on the outer peripheral portion of the rotary feed plate 21, and a permanent magnet 3 is formed therein.
2 are attached respectively. In the case of this embodiment,
The permanent magnet 32 is attached to the outermost surface of the rotary feed plate 21 in the most curved area. In the present embodiment, the through hole 24, the rod connection hole 25, the magnet mounting concave portion, and the permanent magnet 32 are substantially in a straight line (see FIG. 3).

Next, the operation of the electric actuator 1 configured as described above will be described. In an initial state before the power is supplied to the motor 12, the pair of guide rods 23 are almost entirely immersed in the actuator body 2. At this time, the moving body M1 is defined as being at the rearmost position, that is, at the origin position.

When the motor 12 is driven in the forward direction by starting the energization, the output shaft 11 and the screw means 18 connected thereto are integrally formed in a predetermined direction (counterclockwise as viewed from the left side in FIG. 2). Is driven to rotate. At this time, the screw means 18 is provided with a pair of bearings 16 and 17 at both ends.
It rotates while being supported by.

The screw means 18 is connected to the moving body M1 as described above.
Is inserted in a threaded state into the through hole 24 of the rotary feed plate 21 which forms a part of the rotary feed plate 21. Here, in addition to the rotary feed plate 21 having a round cross section (that is, a non-circular cross section), the screw means 18 is inserted at a position different from the guide rod connecting position at the screw feed plate 21. From the above, even in this case, the rotation feed plate 21
Does not follow the screw means 18 and rotate.
Accordingly, the rotary feed plate 21 moves in a direction away from the screw means 18, and accordingly, the moving body M1
Starts moving linearly in the forward direction (leftward direction in FIG. 2). The reason why the rotary feed plate 21 is mechanically fed along the axial direction of the screw means 18 is that both the plates 18 and 2
This is due to the action of the first thread groove. At this time, the pair of guide rods 23, which are a part of the moving body M1, slide in the same direction while being guided by the pair of ball bearings 28.

Next, when the rotation direction of the motor 12 is switched after the moving body M1 reaches the frontmost position, the output shaft 11 and the screw means 18 connected thereto are rotated in the opposite direction (ie, clockwise). Are integrally rotated. At this time, the moving body M1 having the rotary feed plate 21 starts moving linearly in the retreating direction (to the right in FIG. 2). At this time, the pair of guide rods 23 slide in the same direction while being guided by the pair of ball bearings 28. As a result, the guide rod 23 is substantially entirely immersed in the actuator body 2, and the device returns to the initial state.

Therefore, according to the present embodiment, the following effects can be obtained. (1) As described above, the electric actuator 1 of the present embodiment is provided with the high-precision guide mechanism for guiding the moving body M1 straight ahead. Then, as a result of the moving body M1 traveling straight while being guided by this guide mechanism,
The rotation of the moving body M1 is reliably prevented, and the work is less likely to rattle. As described above, the screw means 18
Is inserted in the rotary feed plate 21 at a position different from the guide rod connecting position, which also contributes to the prevention of the rotation of the moving body M1. Therefore, high-precision conveyance and horizontal conveyance that cannot be achieved by the conventional simple rotation preventing mechanism can be performed.

In addition, since it is not necessary to use any guide mechanism separately outside the apparatus, the conventional problem that the entire apparatus is increased in size and weight is also solved. Eliminating the overall increase in size and weight is advantageous in the case where the electric actuator 1 is supported by, for example, a robot arm and the arm is driven at high speed.

(2) In this electric actuator 1, the rotary feed plate 21 and the screw means 18, which are members of the feed screw mechanism, are both housed in the actuator main body 2, and are isolated from the external environment of the apparatus. Therefore, even when the device is used in an environment with a lot of dust, there is no fear that dust adheres to the feed screw mechanism, and excellent dustproofness can be secured at the portion. Of course, since the work mounting plate 22 is located outside the apparatus, there is no problem in mounting the work.

(3) In this electric actuator 1, the rotary feed plate 2 having a thread groove on the inner peripheral surface of the through hole 24
1, a thread groove on the outer peripheral surface and
And a mechanical feed screw mechanism comprising a screw means 18 which is inserted in a state of being screwed into the screw. Then, the rotational movement of the motor 12 is converted into a linear movement by the mechanical feed screw mechanism, and the moving body M1 is moved together with the rotary feed plate 21.
Moves linearly. Further, such a mechanical feed screw mechanism is inexpensive as compared with a magnetic feed screw mechanism, and thus is suitable for reducing the cost of the entire apparatus.

(4) The electric actuator 1 has a configuration in which the rotary feed plate 21 having an oval cross section is accommodated in the accommodation hole 6 having an oval cross section of the actuator body 2 having a flat shape. . As a result, the extra thickness of the tube 3 and the like is reduced, so that the electric actuator 1 can be made thinner, and the entire device can be reduced in size and weight.

(5) In this electric actuator 1, a pair of guide rods 23 are provided with the screw means 18 interposed therebetween. That is, as a result of the straight running guide and the detent being performed at the two separated locations, more reliable straight running guide and the detent can be achieved.

(6) The guide mechanism of the electric actuator 1 has a ball bearing 28 as a contact-type bearing inside.
And a guide rod 23 slidably inserted into the ball bearing 28 thereof. Therefore, the slide between the guide rod 23 and the ball bearing 28 prevents the high precision guide and the rotation of the moving body M1. In addition, such a mechanism requires only a relatively simple structure, which is suitable for cost reduction.

(7) In the electric actuator 1, the bearings 16, 17 provided in the actuator body 2 are provided.
In contrast, both ends of the screw means 18 are rotatably supported. Therefore, since the backlash of the screw means 18 is prevented by being supported at two points by the pair of bearing portions 16 and 17, the screw means 18 can rotate smoothly. Therefore, in addition to more reliably preventing dust from the mechanical feed screw mechanism, it is possible to avoid a decrease in the operability of the device due to rattling.

(8) In this electric actuator 1, the sensor holding groove 7 is formed on the outer peripheral surface of the actuator main body 2, and the permanent magnet 32 is attached to a corresponding position. Therefore, the magnetic sensor 8 can be held at both stroke ends in the sensor holding groove 7. By doing so, when the rotation feed plate 21 reaches near the stroke end, the magnetic sensor 8 is turned on or off in response to the magnetism of the permanent magnet 32. As a result, the end position of the moving body M1 can be detected in a non-contact manner and more accurately than in the case where a contact sensor is used. Of course, the position detection may be performed in a state where the magnetic sensor 8 is held at a position other than the stroke end.

However, two magnetic sensors 8 need not always be provided at both end positions of the stroke. For example, it may be provided at a position for confirming the origin position of the moving body M1, or may be provided at a position where it is desired to move at a high speed when returning to the origin and decelerate just before the origin. In other words, not only two magnetic sensors 8 but also three, four,... May be provided.

(9) In this electric actuator 1, the central axis of the output shaft 11 of the motor 12 and the central axis of the screw means 18 are arranged on the same line. Therefore, both 11,
The size of the entire apparatus can be reduced as compared with a case where a configuration in which the central axes of 18 are not arranged on the same axis is employed.
That is, according to the configuration of the present embodiment, space is saved because transmission means such as belts and gears are not required. Second Embodiment Next, an electric actuator 41 according to a second embodiment of the present invention will be described with reference to FIGS. Here, the points different from the first embodiment are mainly described,
In common, only the same member numbers are given, and the description is omitted.

In the electric actuator 41, a high-precision guide mechanism (so-called linear guide) of a type different from that of the first embodiment is employed. Therefore, the ball bearing 28 is omitted here. Ball bearing 28
Therefore, the rod cover 4 is also thin.

A rectangular plate-shaped table 42 is connected to the work mounting plate 22 so as to be integrally movable.
Bolt holes for work attachment are formed in a plurality of places of the table 42 as needed. In FIG. 5, a guide block 44, which is a component of the linear guide, is fixed to the center of the lower surface of the table 42 by bolts (not shown). The guide block 44 is a member having an engagement groove having a rectangular cross section on its lower surface. The engagement groove is formed so as to extend along the longitudinal direction of the actuator body 2. As a material for forming the guide block 44, a hard metal such as stainless steel is used.

In FIG. 5, a long guide rail 43 is fixed to a central portion of the upper outer peripheral surface of the actuator body 2 by a bolt (not shown). Guide rail 4
Reference numeral 3 denotes a member that forms one linear guide together with the guide block 44 described above. The guide rail 43 has a rectangular cross section, and has a length similar to that of the table 42. As a material for forming the guide rail 43, a hard metal such as stainless steel is used as in the case of the guide block 44. The guide rail 43 extends along the longitudinal direction of the table 42, in other words, the screw means 18.
And extend in parallel along the axial direction of. The guide rail 43 is slidably engaged with the engagement groove of the guide block 44.

Therefore, according to the present embodiment, the following effects can be obtained in addition to the effects (1) to (5), (7) to (9) in the first embodiment. Can be.

(10) As described above, the electric actuator 41 of the present embodiment employs a linear guide composed of the guide rail 43 and the guide block 44 as the high precision guide mechanism. Therefore, the sliding movement of the guide rail 43 and the guide block 44 in the engaged state allows the moving body M1 to move straight while being guided with high precision, and at this time, the work of the moving body M1 is prevented from rotating and the work is prevented. It will be hard to tack. Therefore, high-precision conveyance and horizontal conveyance, which cannot be achieved by the conventional simple detent mechanism, can be reliably performed.

Further, since such a mechanism can be installed on the outer surface of the apparatus, there is an advantage that the size of the actuator main body 2 is hardly restricted. That is, it is permissible to use a large linear guide without increasing the size of the actuator body 2 or the moving body M1. If such a large-sized linear guide is used, more preferable high-precision linear guide function and detent function can be obtained.

(11) Since the electric actuator 41 uses the relatively wide table 42, a work mounting surface having a large area is secured on the upper side. Therefore, the structure is suitable for mounting a large work. Third Embodiment Next, an electric actuator 51 according to a third embodiment of the present invention will be described with reference to FIG. Here, the differences from the first embodiment will be mainly described, and the common points will be denoted by the same reference numerals, and description thereof will be omitted.

In the electric actuator 51 of this embodiment, a feed screw mechanism of a type different from those of the first and second embodiments, that is, a magnetic feed screw mechanism (so-called magnetic screw mechanism) is employed. In the rotary feed plate 21A used here, no particular thread groove is formed on the inner peripheral surface of the through hole 24. Instead, an annular magnetized member 52 is provided on the inner peripheral side of the through hole 24 formed larger. The annular magnetized member 52 has a plurality of magnetized bands spirally magnetized on its inner peripheral surface. The plurality of magnetized bands are provided in the same width and in parallel, and adjacent magnetized bands have different magnetic poles.

On the other hand, unlike the first and second embodiments, the screw means 53 does not have a thread groove on the outer peripheral surface. Instead, a plurality of helically magnetized bands are formed on the outer peripheral surface of the screw means 53. A plurality of magnetized bands are provided in parallel with the same width,
The magnetic poles of adjacent magnetized bands are different.
The screw means 53 is inserted into the annular magnetized member 52 in a non-contact state. The magnetized band on the screw means 53 side and the magnetized band on the annular magnetized member 52 have the same pitch, and a magnetic repulsive force or a magnetic attractive force acts between the opposing magnetized bands. As a result, the rotary feed plate 21A having the annular magnetized member 52 and the screw means 53 constitute one magnetic feed screw mechanism.

Next, the operation of the electric actuator 51 configured as described above will be described. In an initial state before energizing the motor 12, the moving body M1 is at the origin position.

When the motor 12 is driven in the forward direction by starting energization, the output shaft 11 and the screw means 53 are integrally rotated in a predetermined direction. At this time, screw means 5
3 rotates while being supported by a pair of bearings 16 and 17 at both ends.

The screw means 53 is connected to the moving body M1 as described above.
Annular magnetized member 5 of rotary feed plate 21A forming a part of
2 is inserted in a non-contact state. Here, in addition to the rotary feed plate 21A having an oval cross section (that is, a non-circular cross section), the screw means 53 is inserted at a position different from the guide rod connecting position at 21A. From the above, the screw means 53 and the annular magnetized member 5
Even if a magnetic repulsive force or a magnetic attractive force acts between the rotary feed plate 2 and the rotary feed plate 2, the rotary feed plate 21A does not rotate following the screw means 53. Accordingly, the rotary feed plate 21A moves in a direction away from the screw means 53, and accordingly, the moving body M1 starts to move linearly in the forward direction (left direction in FIG. 6). The reason why the rotary feed plate 21A is magnetically fed along the axial direction of the screw means 53 is due to the magnetic repulsive force or magnetic attractive force between the magnetized bands. At this time, the pair of guide rods 23, which are a part of the moving body M1, slide in the same direction while being guided by the pair of ball bearings 28.

Next, when the rotation direction of the motor 12 is switched after the movable body M1 reaches the frontmost position, the output shaft 11 and the screw means 53 are integrally driven in the opposite direction to the rotation direction. At this time, the moving body M1 having the rotary feed plate 21A starts moving linearly in the retreating direction (to the right in FIG. 6). At this time, the pair of guide rods 23 slide in the same direction while being guided by the pair of ball bearings 28. As a result, the guide rod 23 is substantially entirely immersed in the actuator body 2, and the device returns to the initial state.

Therefore, according to the present embodiment, the following effects can be obtained in addition to the effects (1), (2), (4) to (9) in the first embodiment. . (12) The electric actuator 51 of the present embodiment employs the magnetic feed screw mechanism as described above. Therefore, the rotary feed plate 21A having the annular magnetized member 52
The conversion from the rotational motion to the linear motion can be realized without mechanically bringing the screw means 53 into contact with the screw means 53. Therefore, unlike the case using a mechanical lead screw mechanism,
Basically, almost no wear occurs on the portion. Therefore, the device has low dust generation and a long life, and can be used in a clean environment such as a semiconductor manufacturing plant. Moreover, since the structure does not require the supply of the lubricant to the contact portion, it is possible to provide a device having excellent maintainability.

The embodiment of the present invention may be modified as follows. -You may comprise like the electric actuator 61 of another example shown in FIG. Here, guide rod insertion holes 62 are formed at two locations in the head cover 5. Each of the guide rod insertion holes 62 accommodates a ball bearing 63, respectively, through which the guide rod 23A is slidably inserted. Therefore, the pair of guide rods 23A are formed longer in the head side direction than those of the first to third embodiments, and the base ends also protrude outside the actuator body 2.
With such another example of the guide mechanism, it is possible to achieve more reliable straight-ahead guide and detent.

A configuration may be made like another example of the electric actuator 71 shown in FIG. In this alternative example, the width of the rotary feed plate 21 having a round cross section is slightly smaller. In addition, the screw means 18 is arranged eccentrically in the accommodation hole 6, and one guide rod 23 forming a guide mechanism is omitted. Even in the case of such a configuration, a straight running guide and a detent can be achieved, and the size and weight of the device can be further promoted.

A configuration may be made like another example of the electric actuator 81 shown in FIG. In this alternative example, unlike the above embodiment, the through hole 24, the rod connection hole 25,
The magnet mounting recess and the permanent magnet 32 do not exist in a straight line. That is, the sensor holding groove 7 is provided at a corner of the tube 3 constituting the actuator main body 2, and the magnet mounting concave portion and the permanent magnet 32 are arranged at corresponding positions. In this case, the space can be used more effectively, and the size and weight of the device can be further reduced.

In the first to third embodiments and the other examples, the guide rod insertion holes 27 are formed as a pair, and the guide rods 28 are inserted into them. Instead of such a configuration, for example, three or more guide rod insertion holes 27 may be provided.

A spline bearing, for example, may be used as a contact-type bearing in place of the ball bearing 28 as in the first and third embodiments and the other examples, and a spline rod as a guide rod may be inserted therethrough. In this way, even when only one spline bearing is used, a suitable high-accuracy guide function can be obtained, and the structure can be simplified.

The screw means 53 constituting the magnetic feed screw mechanism may be manufactured by a method of helically magnetizing a magnetic material on a non-hollow cylindrical member, or may be manufactured by other methods. Of course, it is good. For example, a method disclosed in Japanese Patent Application Laid-Open No. 8-17625 can be adopted.

In order to electrically detect the moving position of the moving body M1, a detection sensor such as an encoder is connected to the motor 1
2 may be provided. In this way, the movement position can be accurately grasped. The connecting means for connecting the screw means 18 and 53 and the output shaft 11 of the motor 12 is not limited to the coupling 19 used in the first to third embodiments, but other means may be used. Of course, it is good. Instead of the connection using the connecting means, a method of connection using an adhesive or the like may be adopted. Further, a rotational driving force may be directly transmitted to the screw means using an output shaft integrated screw means. With such a configuration, the space can be saved as much as the transmission means is not required, so that the entire apparatus can be further reduced in size and the number of parts can be reduced.

Of course, the motors 12 may be arranged not only in series on the end face side of the actuator body 2 but also in parallel on the outer peripheral face side of the actuator body 2. When the motors 12 are arranged on non-coaxial axes as described above, the entire apparatus can be shortened in the longitudinal direction.
In such a configuration, a transmission means such as a gear or a belt is used.

The mechanical feed screw mechanism is not limited to the one exemplified in the first to third embodiments and the above-mentioned other examples (so-called sliding screw mechanism). A ball screw mechanism or the like may be used. From the viewpoint of feed accuracy, it is more advantageous to select a ball screw mechanism, and from the viewpoint of cost, it is more advantageous to select a slide screw mechanism.

Instead of Embodiments 1 to 3 using the pair of bearings 16 and 17 and the other examples, for example, only the proximal bearing 16 is omitted, or only the distal bearing 17 is omitted. Omission of both 16 and 17 is also permitted. The configuration in which the both 16 and 17 are omitted is suitable, for example, when the above-mentioned screw means integrated with the output shaft is used.

Guide rail 43 for linear guide
May be attached to the moving body M1 side (for example, the center of the lower surface of the table 42), and the guide block 44 may be attached to the fixed side (for example, the center of the upper outer peripheral surface of the actuator body 2).

The permanent magnet 32 does not necessarily have to be provided on the rotary feed plate 21, but is provided on another member (ie, the work mounting plate 22, the guide rod 23, the table 42, etc.) constituting the moving body M1. It is possible that Therefore, the magnetic sensor 8 may also be provided on a member (for example, the cover 4, 5, etc.) other than the tube 3 constituting the actuator body 2.

The work mounting plate 22 and the guide rods 23 and 23A may be formed integrally, or the guide rods 23 and 23A and the rotary feed plates 21 and 21A may be formed integrally.

The working plate is not limited to the work mounting plate 22 as in the first to third embodiments and the above-described other examples, but simply presses the work (in other words, does not aim at mounting the work). ).

The rotary feed plates 21 and 21A are not limited to only a round cross section, but may have an elliptical cross section or a rectangular cross section. The accommodation hole 6 of the tube 3 may also have an elliptical cross section, a rectangular cross section, or the like. Note that the cross-sectional shape of the housing hole 6 of the tube 3 and the cross-sectional shape of the rotary feed plates 21 and 21A are not necessarily similar. In addition, the feeding means such as the rotary feeding plates 21 and 21A is not limited to only the plate-shaped member.

A detection sensor such as an encoder may be provided on the motor 12 in order to electrically detect the moving position of the moving body M1. In this way, the movement position can be accurately grasped. Further, the position detection may be performed using a non-contact type sensor instead of the magnetic sensor 8, for example, for a photo micro sensor. Further, a contact sensor (for example, a limit switch) may be used instead of the non-contact sensor.

Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the above-described embodiments will be listed below together with their effects. (1) The actuator body according to any one of claims 1 to 9, wherein the actuator body includes a cylindrical member and a pair of covers for closing both end surfaces thereof.

(2) In Claims 8 and 9, the bearing portion supports at least a tip portion (preferably both ends) of the screw means. Therefore, this technical idea 2
According to the invention described in (1), the screw means can be more reliably supported.

(3) In any one of claims 1 to 9, the output shaft of the motor and the screw means are coaxially arranged. Therefore, according to the invention described in the technical idea 3, the space can be saved by the amount by which the transmission means is not necessary, and the whole apparatus can be further downsized.

(4) In any one of claims 1 to 9, the output shaft of the motor and the screw means are coaxially arranged and integrated. Therefore, according to the invention described in the technical idea 4, the space can be saved by the amount that the transmission means is not necessary, and the whole device can be further downsized, and the number of parts can be reduced. .

(5) In the ninth aspect, the sensor holding groove has an equal cross-sectional shape, and the cross-sectional shape is a substantially inverted T-shape or a substantially dovetail cross-sectional shape. Therefore, according to the invention described in the technical idea 5, the sensor can be held in the sensor holding groove so that the position can be changed and the sensor cannot be dropped.

(6) The electric actuator according to claims 6 to 9, wherein the bearing portion is a ball bearing. (7) The electric actuator according to claims 6 to 9, wherein the bearing portion is a spline bearing, and the guide rod is a spline rod. Therefore, according to the invention described in the technical concept 7, a highly accurate guide function can be obtained even with one bearing portion.

(8) The electric actuator according to claim 9, wherein the sensor holding groove is provided at a corner of the actuator body. Therefore,
According to the invention described in the technical idea 8, the space can be used more effectively, and the size and weight of the device can be further reduced.

[0093]

As described in detail above, according to the first to ninth aspects of the present invention, it is possible to provide an electric actuator which is capable of high-precision conveyance and horizontal conveyance and is excellent in dustproofness. it can.

According to the second aspect of the present invention, it is possible to reduce the cost of the entire apparatus. According to the third aspect of the invention, it is possible to provide an electric actuator having low dust generation and long life.

According to the fourth aspect of the invention, the size and weight of the entire device can be reduced. According to the fifth aspect of the present invention, more reliable straight running guide and detent can be achieved.

According to the sixth aspect of the present invention, since the structure can be relatively simple, it is possible to reduce the cost. According to the invention described in claim 7, it is allowed to use a large linear guide without increasing the size of the actuator body or the moving body.

According to the eighth aspect of the invention, it is possible to further reduce dust generation. According to the ninth aspect, the moving position of the moving body can be detected in a non-contact and accurate manner.

[Brief description of the drawings]

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

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 1;

FIG. 4 is a perspective view of an electric actuator according to a second embodiment.

FIG. 5 is a sectional view taken along line CC in FIG. 4;

FIG. 6 is a sectional view of an electric actuator according to a third embodiment.

FIG. 7 is a cross-sectional view of another example of an electric actuator.

FIG. 8 is a cross-sectional view of another example of the electric actuator.

FIG. 9 is a cross-sectional view of another example of an electric actuator.

[Explanation of symbols]

1, 41, 51, 61, 71, 81: electric actuator, 2: actuator main body, 6: accommodation hole having a round cross section, 7: sensor holding groove, 12: motor, 16, 17: bearing part, 18, 53 ... Screw means, 21, 21A (plate-like) Rotary feed plate as feed means, 22: Work mounting plate as working plate, 23, 23A ... Guide rod, 24 ... Through-hole of feed means, 28, 63 ... Contact Ball bearing as a type bearing, 32 permanent magnets, 4
3 ... guide block, 44 ... guide rail, M1 ... moving body.

Claims (9)

[Claims] The present invention is characterized in that a rotary motion of a motor attached to an actuator body is converted into a linear motion by a feed screw mechanism comprising a feed means rotationally driven by the motor and a screw means inserted through the feed means. An electric actuator for linearly moving a moving body having the feed means in a part thereof along an axial direction of the screw means; a screw means rotatably housed in the actuator body; and the actuator. A feeding means accommodated reciprocally in the main body, a working plate provided outside the actuator main body, and disposed so as to penetrate the actuator main body, and the feeding means and the working plate can be integrally moved. A moving body including a guide rod coupled to the moving body; and a guide mechanism for guiding the moving body to move straight. Provided, electric actuator, characterized in that said screw means is inserted through a position different from the guide rod connecting position in said feeding means. 2. The feed screw mechanism according to claim 1, wherein the feed screw mechanism has a screw groove on an inner peripheral surface of the through hole, and a screw having a screw groove on the outer peripheral surface and inserted in a state of being screwed into the through hole of the feed means. The electric actuator according to claim 1, wherein the electric actuator is a mechanical feed screw mechanism comprising: 3. The feed screw mechanism has a feed means having a magnetized band spirally magnetized on the inner peripheral surface of the through hole, and a magnetized band spirally magnetized on the outer peripheral surface. 2. A magnetic feed screw mechanism comprising a screw means inserted through a through hole of the feed means in a non-contact state.
3. The electric actuator according to claim 1. 4. A feeding means having an oval cross section is accommodated in an accommodation hole having an oval cross section of an actuator main body having a flat shape.
The electric actuator according to any one of the above items. 5. The electric actuator according to claim 4, wherein a pair of said guide rods are provided with said screw means interposed therebetween. 6. The guide mechanism is formed so as to extend in the longitudinal direction of the actuator body, and has a guide rod insertion hole having a contact type bearing portion therein, and slides in the contact type bearing portion. The electric actuator according to any one of claims 1 to 5, comprising the guide rod inserted so as to be capable of being inserted. 7. The guide mechanism is a linear guide comprising a long guide rail and a guide block slidably engaged with the guide rail, and one of the guide rail and the guide block is connected to the linear guide. The electric actuator according to any one of claims 1 to 5, wherein the electric actuator is attached to a moving body and the other is attached to the actuator body. 8. The apparatus according to claim 1, wherein an end of said screw means is rotatably supported by a bearing provided in said actuator body. Electric actuator. 9. A sensor holding groove extending along a longitudinal direction of the actuator body is formed on an outer peripheral surface of the actuator body, and a permanent magnet is attached to a position corresponding to the sensor holding groove on an outer peripheral portion of the feeding means. The electric actuator according to any one of claims 1 to 8, wherein: