JP2002276617A - Linear actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear actuator smaller and lighter and capable of being manufactured at lower cost. SOLUTION: A piston mechanism 4 is reciprocated by the supply/discharge of a pressure fluid to/from a pressure chamber in a body 1 and a movable body 2 is integrally moved in conjunction therewith while being guided by a guide mechanism 3. A position detecting mechanism 5 for detecting the position of the movable body 2 consists of a detected body 53 to be moved integrally with the movable body 2 and a position sensor 55 for outputting a signal as the detected body 53 approaches. The position sensor 55 is mounted in a sensor mounting groove 54 in one side of a fixed portion 1 in such a manner as to be adjustable in the same direction in mounting and positioning work.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear actuator for reciprocating a moving body along an axial direction of a fixed portion by introducing a pressure fluid such as compressed air, and more particularly, to detecting a position of the moving body. The present invention relates to a linear actuator provided with a position detecting mechanism.

[0002]

2. Description of the Related Art Conventionally, a linear actuator used as a means for transporting a work or the like has been known. This type of linear actuator conveys a work or the like placed on the moving body by reciprocating the moving body linearly along a fixed portion.

A linear actuator generally has a position detecting mechanism comprising a permanent magnet provided on a piston and a magnetic proximity switch attached to a fixed portion. However, the material of the fixed portion is a magnetic material. Or, when the magnetic proximity switch cannot be arranged near the piston, a position detecting mechanism in which a permanent magnet is mounted on the moving body may be used.

For example, as a conventional technique, Japanese Utility Model Laid-Open No. 2-9
The linear actuator (slide cylinder device) disclosed in Japanese Patent No. 0405 is a position detection mechanism having a pair of magnets embedded on both sides of a moving body and a pair of position sensors disposed on both sides of a fixed part. It has.

However, the following problems are pointed out in the technology described in the above publication. First, in the automated equipment, a plurality of position sensors are attached to the linear actuator in order to detect both the outgoing end and the return end of the moving body. Since the operation has to be performed from both sides of the linear actuator, there is a disadvantage that workability is poor. Moreover, since two magnets are embedded in the moving part,
Production costs increase.

As another prior art, for example, JP-A-8-152006 discloses a linear actuator in which a sensor mounting member having two upper and lower sensor mounting grooves is mounted on one side surface of a body. In this linear actuator, the amount of displacement of the slide table, which is a moving body, is regulated by a pair of adjusting members provided on end blocks at both ends in the moving direction.

However, according to this configuration, a foreign matter such as a screw or a nut easily enters between the sensor mounting member and the permanent magnet and is easily caught by the foreign matter. The sensor may malfunction. Further, when the permanent magnet attracts a foreign substance made of a magnetic material, the magnetic field is changed by this, and there is a possibility that the position sensor may malfunction.

Further, since the sensor mounting member having the sensor mounting groove must be manufactured separately, the manufacturing cost is increased, and the size of the fixing portion is increased by the fixing means for fixing the sensor mounting member to the body. I will.
In addition, since the slide table, the permanent magnet, and the sensor mounting member are provided to overlap in the width direction, the size of the linear actuator increases in the width direction. Generally, there is a demand for this type of actuator to reduce the space in the mounting plane, and thus the above configuration is contrary to such a demand. Note that the width of the slide table is restricted by the guide mechanism and must be strong enough to cope with the load, so it is difficult to reduce the width.

In this type of linear actuator, the stop position accuracy of the slide table is required to be as small as possible, and its direction is desirably limited to one of the vertical and horizontal directions. However, in the linear actuator disclosed as the second embodiment in the above-mentioned Japanese Patent Application Laid-Open No. H8-152006, a pair of adjustment members for regulating the stroke end position and the stroke amount of the slide table are disposed obliquely above the pressure chamber. Therefore, the slide table abuts on the adjustment member at the stroke end and is displaced up, down, left, and right. Further, since the adjusting member and the pressure chamber are relatively far apart, a large moment acts on the guide mechanism at the stroke end. Therefore, not only does the life of the slide table be adversely affected, but also the displacement of the slide table due to the moment increases, making it difficult to improve the stop position accuracy.

Further, since a pair of ports for selectively introducing compressed air into the pair of pressure chambers are provided in the end blocks at both ends of the fixed portion, respectively, the pipes may be arranged in the axial direction of the linear actuator. In addition, the piping is complicated, and the piping laid in parallel with the linear actuator not only hinders the movement of the moving body, but also increases the mounting space in the axial direction.

Further, since the fixing portion and the slide table are made of a hard material, the workability is poor and the manufacturing cost is high. In addition, the mass of the linear actuator increases, and the weight cannot be reduced.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and a technical problem thereof is to provide a linear actuator that is small, lightweight, and can be manufactured at low cost. To provide.

Another technical problem is to provide a linear actuator which can perform a highly reliable operation by preventing a foreign object from coming into contact with an object to be detected.

[0014]

Means for Solving the Problems The technical problems described above are:
This can be effectively solved by the present invention. That is, the linear actuator according to the first aspect of the present invention has a fixed portion having a pair of pressure chambers partitioned by a piston mechanism, and is connected to the fixed portion via a guide mechanism so as to be relatively displaceable in the axial direction. A moving body to be moved, and a position detecting mechanism for detecting a position of the moving body, a plurality of sensor mounting grooves extending in an axial direction are provided on one side of the fixed portion, and the position detecting mechanism is The sensor comprises an object to be detected attached to the moving body, and a position sensor which is fixedly attached to an arbitrary position in the longitudinal direction of the sensor mounting groove and outputs a signal when the object to be detected approaches.

In the above configuration, the piston mechanism reciprocates in the axial direction by supplying and discharging the pressurized fluid to and from the pressure chamber, and accordingly, the moving body integrally moves while being guided by the guide mechanism. The position detection mechanism detects an object to be detected that moves integrally with the moving object by the position sensor,
Detect the position of the moving object. Since the position sensor is mounted in the sensor mounting groove on one side of the fixed portion, the mounting and the adjustment of the mounting position can be performed from the same direction.

According to a second aspect of the present invention, there is provided the linear actuator according to the first aspect, wherein the fixed portion is provided with a housing space in which the object to be detected can move in the axial direction, and the opening of the housing space is covered by the moving body. Thus, foreign matters made of a magnetic material or the like cannot enter the housing space.

A linear actuator according to a third aspect of the present invention is the linear actuator according to the first or second aspect, further comprising a stroke adjusting mechanism capable of regulating a stroke amount of the moving body and adjusting a stroke end position. , An overhanging portion that protrudes above the pressure chamber at the end of the fixed portion, and an adjusting member that is fixed to the overhanging portion so as to be able to advance and retreat in the axial direction. It is something that is improved.

According to a fourth aspect of the present invention, in the linear actuator according to the first or second aspect, a port connectable to a pressure fluid supply source and communicated with one of the pressure chambers is provided at one end surface of the fixed portion; A port that can be connected to a pressure fluid supply source and communicates with the other pressure chamber is opened, and a port that is connectable to a pressure fluid supply source and communicates with one pressure chamber on the other end surface of the fixed portion, A port that can be connected to the pressure fluid supply source and communicates with the other pressure chamber is opened, so that the port connected to the pressure fluid supply source can be selected according to conditions such as piping. Things.

According to a fifth aspect of the present invention, in the linear actuator according to the first or second aspect, the guide mechanism is provided on the movable body so as to face the concave groove provided in the fixed portion and the concave groove. It has two-to-four bearing races arranged vertically above and below the concave groove, and a plurality of rolling elements rotatably arranged between the bearing races, and arc-shaped at both corners of each concave groove. Forming a concave surface, forming an arc-shaped convex surface on a contact surface of the bearing race with the arc-shaped concave surface, and making the radius of curvature of the arc-shaped concave surface equal to or slightly larger than the radius of curvature of the arc-shaped convex surface. By
This is to reduce the stress generated at the contact portion between the bearing race and the concave groove.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a linear actuator according to the present invention will be described below with reference to the drawings. First, FIG. 1 is a plan view of a linear actuator according to the present invention, FIG.
3 is a view taken in the direction of arrow III in FIG. 1, FIG. 4 is a bottom view, FIG. 5 is a sectional view taken along line VV in FIG. 1, and FIG.
VI-VI sectional view, FIG. 7 is a partially enlarged sectional view.

As shown in FIGS. 1 to 7, the linear actuator according to this embodiment has a body 1, which is a fixed portion, a table 2, which is a moving body, and a body 1 and a table 2 which are moved in the axial direction. A guide mechanism 3 that is connected to the table 2 so as to be relatively displaceable, a piston mechanism 4 that moves inside the body 1 by introducing compressed air to move the table 2, a position detection mechanism 5 that detects the position of the table 2, A stroke adjusting mechanism 6 that regulates a stroke amount and adjusts a stroke end position.

As shown in FIG. 5, a through hole 11 is formed in the body 1 at a substantially central portion in the width direction so as to penetrate in the axial direction. Both ends of the through hole 11 have O-rings 13 mounted on the outer periphery. The closing members 12L and 12R are closed by the closing members 12L and 12R, respectively, and the closing members 12L and 12R are fixed by the hole retaining rings 14, respectively.

A pair of pressure chambers 7L, 7R are defined between the through-hole 11 and the closing members 12L, 12R at both ends by a piston mechanism 4 inserted into the through-hole 11 so as to be movable in the axial direction. The piston mechanism 4 is a piston
1, a pair of pistons 42L, 42R arranged at both ends thereof in a non-adhesive manner, and a piston seal 43 mounted on the outer periphery of each of the pistons 42L, 42R.

At the center of the upper surface of the body 1 in the width direction, a central convex portion 15 extending linearly in the axial direction is formed.
At the center in the width direction on the lower surface of the table 2, a central concave portion 21 corresponding to the central convex portion 15 is formed, and both are fitted to each other so as to be relatively movable in the axial direction.

As shown in FIGS. 5 and 6, an opening 16 opened in the through-hole 11 is formed at an intermediate portion in the axial direction on the upper surface of the central convex portion 15 of the body 1. The engagement member 22 is inserted into the engagement hole 41a formed substantially at the center in the axial direction of the piston axle 41 with some play and engaged therewith. Engaging member 2
2 is provided with a male screw 22a at the upper end, and is coupled to the table 2 by being screwed into a female screw 23 opened substantially at the center of the table 2. Opening 16
Is a long hole extending in the axial direction of the body 1, that is, the moving direction of the table 2, and has a length corresponding to the sum of the maximum stroke amount of the table 2 and the diameter of the engaging member 22.

As shown in FIG. 4, ports 71a and 72a are provided on one end face of the body 1 on both sides of the through hole 11 (one pressure chamber 7L), and on the other end face. Ports 71b and 72b are provided on both sides of the through hole 11 (the other pressure chamber 7R). The ports 71a and 71b communicate with each other via a flow path 71 and communicate with one pressure chamber 7L via a flow path 71c branched from the flow path 71. Similarly, port 72
a and 72b communicate with each other via a flow path 72,
It communicates with the other pressure chamber 7R via a flow path 72c branched from the flow path 72.

In the illustrated example, as shown in FIG. 4, ports 71b and 72b are closed by plugs 73, respectively, and supply and discharge of compressed air to and from pressure chambers 7L or 7R are performed by ports 71a and 72a. Is to be done through. Conversely, depending on the arrangement of the linear actuator and the piping, the ports 71a and 72a
And supply and discharge of compressed air to and from the pressure chamber 7L or 7R through the ports 71b and 72b.
The port to be used can be selected according to the conditions. Therefore, the piping can be easily and simply arranged, and the relative position between the piping and a position sensor (a magnetic proximity switch 55 described later) can be selected, so that the equipment can be downsized. Further, the piping does not hinder the movement of the table 2.

As shown in FIG. 7, the guide mechanism 3 has a pair of concave grooves 31 formed on both outer surfaces of the central convex portion 15 of the body 1 and extending in the axial direction (only one side is shown in FIG. 7). And a pair of concave grooves 32 formed on both inner side surfaces of the central concave portion 21 of the table 2 so as to face the pair of concave grooves 31, respectively, and a total of four pairs are arranged in each of the concave grooves 31, 32. , And a required number of balls 34 as rolling elements, which are rotatably interposed in the gap surrounded by the bearing races 33, 33,. . The table 2 can move linearly in the axial direction along the central convex portion 15 of the body 1 through the guide mechanism 3.

The bearing race 33 has a substantially D-shaped rod shape in cross section cut perpendicular to the longitudinal direction, that is, the surface thereof has an arc-shaped convex surface 33a having an arc-shaped cross section and a flat surface having a straight line shape. Part 33b. Further, at the upper and lower corners of the concave grooves 31 and 32, arc-shaped concave surfaces 31a and 32a each having a circular cross-sectional shape cut perpendicular to the longitudinal direction are formed. Each of the bearing races 33 is such that the arc-shaped convex surface 33a is
1a or 32a and a flat portion 33b
Are opposed to each other in a diagonal direction.

The stress generated at the contact portion between the concave grooves 31 and 32 and the bearing race 33 is caused by arcuate concave surfaces 31a and 32a.
Is set to be the same as or slightly larger than the radius of curvature of the arc-shaped convex surface 33a.
Therefore, a relatively large force can be applied. Although the ball 34 is in contact with the flat portion 33b of each bearing race 33, the stress generated in the contact portion is reduced by the grooves 31 and 3.
A ball 34 having a size that is at the same level as the stress generated at the contact portion between the bearing race 2 and the bearing race 33 is selected.

The bearing race 33 and the ball 34 are
Manufactured from hard materials such as high carbon chromium bearing steel and martensitic stainless steel to ensure the required strength,
After the heat treatment, precise finishing is performed by polishing. Therefore, by selecting the size of the ball 34 and the thickness of the bearing race 33, the gap between the concave grooves 31, 32, the ball 34 and the bearing race 33, that is, The gap between the body 1 and the table 2 can be adjusted in microns.

As shown in FIGS. 2 and 3, the body 1
At the bottom of the pair of concave grooves 31, pan screws 35 are respectively mounted on both ends of the bearing race 33 in the longitudinal direction.
The ball 34 is prevented from falling off the ball. End plates 37 are fixed to both end surfaces in the movement direction of the table 2 by pan screws 36, respectively, thereby preventing the balls 34 from falling off the bearing races 33.

The bearing race 33 is formed by forming an arc-shaped convex surface 33a by centerless polishing, and then polishing the flat portion 3 by planar polishing.
3b, the productivity is good, and the production cost is greatly reduced without lowering the performance as compared with the conventional guide mechanism in which ball rolling grooves are formed directly on the body 1 and the table 2. Can be reduced.

As described above, since the stress generated at the contact portion between the concave grooves 31 and 32 and the bearing race 33 is suppressed to a small value, the guide performance for the movement of the table 2 is reduced.
It is not necessary to depend only on the rigidity of the body 1 and the table 2. As a result, the body 1 and the table 2 can be made of a light-weight material excellent in workability, so that the weight and manufacturing cost of the linear actuator can be reduced.

In this embodiment, the body 1 and the table 2 are made of extruded material such as aluminum alloy which is a non-magnetic material which is lightweight and has excellent corrosion resistance and workability. In the manufacturing process, the molding of the cross-sectional shape shown in FIG. 6 has been completed. Therefore, the body 1 and the table 2 are formed by cutting the extruded material to a required length and performing tapping or finishing.
It can be easily manufactured. Further, since required heat treatment and surface treatment are performed at the stage of the extruded material, the production cost can be significantly reduced.

As shown in FIG. 6, the position detecting mechanism 5 is provided with a pan screw 52 on the lower surface of one sleeve 24 of the table 2.
As shown in FIGS. 2, 3 and 6, a magnetic plate 51 fixed by the magnetic plate 51, a plate-shaped permanent magnet 53 as a detection target attached to the magnetic plate 51,
A substantially parallel upper and lower sensor mounting groove 54 (54U, 54L) that opens on the side surface of one shoulder 17 of the body 1, and a position sensor that can be engaged at any position in the longitudinal direction of each sensor mounting groove 54. A certain magnetic proximity switch 55 (55U,
55L).

The magnetic proximity switch 55 detects the magnetic field by the approach of the permanent magnet 53, and outputs an electric signal to the outside.
The magnetic proximity switch 55U fixed to U
Is provided so as to correspond to the position of the permanent magnet 53 at the time of moving to one stroke end position, and the magnetic proximity switch 55L fixed to the lower sensor mounting groove 54L is arranged such that the table 2 has the stroke end position on the opposite side. Are provided so as to correspond to the positions of the permanent magnets 53 when the permanent magnets 53 have been moved. The reference numeral 55a in FIGS. 1, 3, 4 and 6
Is a lead derived from each magnetic proximity switch 55.

According to the position detecting mechanism 5 having this configuration, the mounting of the two magnetic proximity switches 55U and 55L and the adjustment of the mounting positions can be performed from the same direction, and the workability is good. Further, a permanent magnet 53 is attached to the lower surface of one sleeve portion 24 of the table 2, and the sensor attachment grooves 54U, 54L
Are formed integrally with the body 1, the position detection mechanism 5 can be configured to be relatively small and inexpensive.

One sleeve 2 of table 2 is attached to body 1.
4 (Shoulder on sensor mounting groove 54 side)
An accommodation space 17 a extending in the axial direction is formed in the housing 17. On the lower surface of one sleeve 24 of the table 2, a pan screw 52
And permanent magnet 5 fixed via magnetic plate 51
3 is accommodated in the accommodation space 17a, and can be displaced in the axial direction in the accommodation space 17a with the displacement of the table 2.

The permanent magnet 53 is formed by magnetizing different magnetic poles on the surface on the sensor mounting groove 54 side close to the left and right, so that an arc-shaped magnetic field heading toward the sensor mounting groove 54 and the back side passing through the magnetic plate 51. A closed loop is formed by this magnetic field, and is less affected by an external magnetic material. Therefore, the permanent magnet 53 accompanying the movement of the table 2
, The operation of the magnetic proximity switch 55 that outputs a signal is stabilized, and the position detection accuracy can be improved.

The accommodation space 17a in which the permanent magnet 53 is accommodated
Is provided in a range where the movement of the permanent magnet 53 by the stroke of the table 2 is allowed, and is always below the sleeve 24 of the table 2 irrespective of the position of the table 2. For example, as shown in FIG. 1, even when the table 2 is at the stroke end position, the accommodation space 17a is hidden below the table 2. The accommodation space 17
The lower opening of “a” is closed by a member (not shown) of equipment to which the linear actuator is fixed. Therefore, foreign matter such as screws and nuts does not enter the housing space 17a and come into contact with the permanent magnet 53, and malfunction of the linear actuator due to contact with the foreign matter, failure of the position detecting mechanism 5, magnetic field Can be prevented from deteriorating the position detection accuracy due to the change in

In place of the sleeve 24 of the table 2,
By the end plate 37 attached to the end face of the table 2,
It is also possible to cover the upper opening of the accommodation space 17a, and the effect is the same.

[0043] formed at both ends of the sensor mounting groove 54 having one sleeve portion side centrally required length of 24 of the body 1, as shown in FIGS. 1 and 4, the space Sa, Sb is stepped Have been. Therefore, even if both ends of the linear actuator in the axial direction are closed by other members, each magnetic proximity switch 55 is moved from one side of the body 1 to the space Sa or Sb.
Can be inserted into and removed from each sensor mounting groove 54, and the workability is very good.

As shown in FIGS. 1, 2, 3 and 5, the stroke adjusting mechanism 6 is integrally formed at both ends in the longitudinal direction of the body 1 so as to extend further upward from the central convex portion 15. A pair of overhangs 61L and 61R and a pair of adjustment members 62 which are threadably inserted into female screws 61a axially opened in the pair of overhangs 61L and 61R, respectively.
L, 62R, fixing members 63L, 63R screwed to these adjusting members 62L, 62R, and adjusting members 62L, 6R.
It consists of buffer members 64L and 64R provided at the tip of 2R. That is, each of the adjusting members 62L and 62R adjusts the axial position to a desired position by screwing into the female screw 61a, and then screwing the fixing members 63L and 63R to form the protruding portions 6L.
The stroke end position of the table 2 is defined by displacing the table 2 and bringing the end plate 37 into contact with the buffer member 64L or 64R.

The adjusting members 62L, 62R are provided with the pressure chambers 7L,
7R, the pressure chamber 7
The moment generated when the end plate 37 of the table 2 which moves together with the piston mechanism 4 by the supply and discharge of the compressed air to the L and 7R abuts on the buffer member 64L or 64R at the stroke end is minimized, and Since the displacement of the table 2 due to this is limited in the vertical direction, the stop position accuracy is improved. In addition to this, the adjusting member 62
Since the distance between L and 62R and the guide mechanism 3 is short, the displacement due to the bending of the member can be suppressed to a small value.

The stroke adjusting mechanism 6 includes a table 2
Buffer members 64L, 64R of a pair of adjustment members 61L, 61R fixed to overhangs 61L, 61R formed on body 1
Since the table 2 has a simple configuration in which the table 2 is stopped at the stroke end position by contacting any one of them, the stroke adjusting mechanism 6 can be manufactured relatively small and inexpensive.

As shown in FIG. 1, on the upper surface of the table 2, there are provided a plurality of female screws 2a for fixing a jig and the like, and round holes 2b and long holes 2c for mounting positioning pins. As shown in FIG. 4, the body 1 has a plurality of female screws 18 for fixing the linear actuator to a predetermined location such as equipment, and a round hole 1 for attaching a positioning pin.
a and a long hole 1b are provided.

As shown in FIGS. 1 and 2, the female screw 1
Reference numeral 8 denotes a bottomed cylindrical hole 18a having a size large enough to receive the head of the mounting bolt, and formed through the shoulder of the body 1 vertically so that the mounting bolt can be inserted from above. I have. Therefore, even if the mounting bolt is inserted through the female screw 18, the head of the mounting bolt is housed in the bottomed cylindrical hole 18a, does not protrude from the body 1, and does not hinder the table 2 from moving. Since the female screws 18 are formed at the four corners of the body 1, the body 1 is unlikely to bend even when an external force is applied from a member attached by a mounting bolt screwed into the female screw 18, and the rigidity of the linear actuator is increased.

Next, the operation of the linear actuator of the present invention configured as described above will be described. FIGS. 1, 3 and 5 show that compressed air is introduced into the pressure chamber 7L from the port 71a via a switching valve from a compressed air supply source (not shown), and the other pressure chamber 7R is connected to the port 72a by the port 72a. It is open to the atmosphere through a switching valve that is not in operation.

In this state, the pressure of the compressed air introduced into the pressure chamber 7L causes the piston mechanism 4 composed of the pistons 42L and 42R and the piston axle 41 to move.
The table 2 moves to the R side, and presses the table 2 through the engaging member 22 toward the overhang portion 61R. The table 2 is stopped when the end plate 37 provided on the end surface thereof comes into contact with the buffer members 64L and 64R provided at the tip of the adjustment member 62. The permanent magnet 53 mounted on the lower surface of the sleeve 24 of the table 2 is located at an end of the accommodation space 17a near the pressure chamber 7R, and the magnetic field is transmitted to the lower sensor mounting groove 54.
By detecting the magnetic proximity switch 55L attached to L, a stop position detection signal is sent to a sequencer (not shown) or the like.

The stop position of the table 2 on the side of the overhang 61R is determined by loosening the fixing member 63R of the stroke adjusting mechanism 6, adjusting the screwing amount of the adjusting member 62R into the overhang 61R, and tightening the fixing member 63R again. By fixing, it can be adjusted and changed appropriately.

Next, by switching a switching valve (not shown) provided on the pipe from the compressed air supply source, compressed air is introduced from the port 72a into the pressure chamber 7R, and
When the compressed air filled in the pressure chamber 7L is released to the atmosphere via the port 71a and the switching valve, the piston mechanism 4 including the pistons 42L, 42R and the piston acrus 41 is activated by the pressure of the compressed air in the pressure chamber 7R. Then, the inside of the through hole 11 is integrally moved to the left side (the pressure chamber 7L side) in FIG. For this reason, the table 2 connected to the piston mechanism 4 via the engaging member 22 extends on the body 1
It moves toward the L side, and the permanent magnet 53 moves in the accommodation space 17a integrally therewith.

At this time, the table 2 moves with the body 1
Outer surfaces of the central convex portion 15 and the central concave portion 21 of the table 2
Are guided by the guide mechanism 3 configured between the two. The guide mechanism 3 is provided between the bearing races 33, 33 arranged in the concave groove 31 on the body 1 side and the bearing races 33, 33 arranged in the concave groove 31 on the table 2 side and moving together with the table 2. The rolling of the rows of the balls 34 enables the table 2 to move smoothly.

The table 2 that moves toward the overhang portion 61L has an end plate 37 provided on the end surface thereof.
L stops when it comes into contact with the buffer member 63L provided at the tip of L. Since the cushioning member 63L is made of an elastic body, it effectively absorbs the impact and sound caused by the contact. At this time, the permanent magnet 53 is located at an end near the pressure chamber 7L in the accommodation space 17a, and transmits the magnetic field to the magnetic proximity switch 5 mounted on the upper sensor mounting groove 54U.
5U detects and sends a stop position detection signal to a sequencer or the like (not shown).

The stop position of the table 2 on the side of the overhang 61L is adjusted by loosening the fixing member 63L of the stroke adjusting mechanism 6, adjusting the screwing amount of the adjusting member 62L into the overhang 61L, and tightening the fixing member 63L again. By fixing it, it can be adjusted and changed appropriately.

[0056]

According to the linear actuator according to the first aspect of the present invention, the position detecting mechanism for detecting the position of the moving body is provided on the object to be detected attached to the moving body and on one side of the fixed portion. The position sensor is mounted in each of the plurality of sensor mounting grooves provided, so that the position sensor can be mounted and the mounting position can be adjusted from the same direction, thereby improving workability. Further, the position detecting mechanism can be made relatively small and inexpensive.

According to the linear actuator according to the second aspect of the present invention, the object to be detected, which moves together with the moving body, is located in the accommodation space formed in the fixed portion and covered by the moving body. This prevents the linear actuator from malfunctioning and the position detecting mechanism from malfunctioning or malfunctioning.

According to the linear actuator according to the third aspect of the present invention, the stroke adjusting mechanism that regulates the stroke amount of the moving body and can adjust the stroke end position protrudes above the pressure chamber at the end of the fixed portion. With an overhang,
With the configuration including the adjustment member fixed to the overhang portion so as to be able to move forward and backward, the stroke adjustment mechanism can be configured simply and compactly, the manufacturing cost can be reduced, and the stopping position accuracy of the moving body can be reduced. Can be improved.

According to the linear actuator according to the fourth aspect of the present invention, since the port communicating with one pressure chamber and the port communicating with the other pressure chamber are opened at both end surfaces of the fixed portion, the port is connected to the pressure fluid supply source. The port to be connected can be selected according to conditions such as piping. For this reason, the piping work can be performed easily, and the size of the equipment can be reduced by selecting the relative position between the piping and the position detection sensor.
Piping can be prevented from hindering the movement of the moving body.

According to the linear actuator according to the fifth aspect of the present invention, the guide mechanism is provided between the two-to-four bearing races arranged in the groove on the fixed portion side and the groove on the moving body side. By disposing the moving body and making the radius of curvature of the arc-shaped concave surface formed at both corners of each groove the same as or slightly larger than the radius of curvature of the arc-shaped convex surface of the bearing race in contact with the groove, the bearing race and the groove are formed. Since the stress generated at the contact portion with the moving body is reduced, it is not necessary for the guiding performance for the moving body to depend only on the rigidity of the fixed portion and the moving body, and as a result, the fixed body and the moving body have excellent workability and are lightweight Therefore, the weight of the linear actuator can be reduced and the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a plan view showing a preferred embodiment of a linear actuator according to the present invention.

FIG. 2 is a view taken in the direction of arrow II in FIG.

FIG. 3 is a view in the direction of the arrow III in FIG. 1;

FIG. 4 is a bottom view showing the embodiment.

FIG. 5 is a sectional view taken along line VV in FIG.

FIG. 6 is a sectional view taken along line VI-VI in FIG.

FIG. 7 is a partially enlarged sectional view.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Body (fixed part) 17a Housing space 2 Table (moving body) 3 Guide mechanism 31, 32 Concave groove 31a, 32a Arc-shaped concave surface 33 Bearing race 33a Arc-shaped convex surface 34 Ball 4 Piston mechanism 41 Piston aculus 42L, 42R Piston 5 Position detection mechanism 53 Permanent magnet (detected body) 54 (54U, 54L) Sensor mounting groove 55 (55U, 55L) Magnetic proximity switch (position sensor) 6 Stroke adjustment mechanism 61L, 61R Overhang 62L, 62R Adjusting member 63L, 63R Fixing member 64L, 64R Buffer member 7L, 7R Pressure chamber 71, 71c, 72, 72c Channel 71a, 71b, 72a, 72b Port

Claims (5)

[Claims] 1. A fixed portion (1) having a pair of pressure chambers (7L, 7R) partitioned by a piston mechanism (4), and the fixed portion (1) is axially connected to the fixed portion (1) via a guide mechanism (3). A moving body (2) which is connected to be relatively displaceable and is moved by the piston mechanism (4); and a position detecting mechanism (5) for detecting the position of the moving body (2).
A plurality of sensor mounting grooves (54) extending in the axial direction are provided on one side of the fixed portion (1), and the position detection mechanism (5) is mounted on the moving body (2). The object to be detected (53) and the sensor mounting groove (5
4) A linear actuator comprising a position sensor (55) fixedly attached to an arbitrary position in the longitudinal direction and outputting a signal when the detected object (53) approaches. 2. An accommodation space (17a) in which an object to be detected (53) can move in the axial direction is provided in the fixed portion (1), and an opening of the accommodation space (17a) is covered by the moving body (2). The linear actuator according to claim 1, wherein: 3. A stroke adjusting mechanism (6) capable of regulating a stroke amount of a moving body (2) and adjusting a stroke end position, wherein the stroke adjusting mechanism (6) is provided at an end of a fixed portion (1). The projecting portion (61) projecting above the pressure chambers (7L, 7R)
3. The linear actuator according to claim 1, wherein the linear actuator comprises: an adjustment member fixed to the projecting portion so as to be able to advance and retreat in the axial direction. 4. A port (71a) that can be connected to a pressure fluid supply source and communicates with one pressure chamber (7L) at one end surface of the fixed portion (1), and can be connected to a pressure fluid supply source. A port (72a) communicating with the other pressure chamber (7R) is opened, and the other end surface of the fixed portion (1) is connectable to a pressure fluid supply source and communicates with the one pressure chamber (7L). Port (7
The linear actuator according to claim 1 or 2, wherein a port (72b) that can be connected to the pressure fluid supply source and communicates with the other pressure chamber (7R) is opened. 5. A groove (31) provided on the fixed part (1) and a groove (3) provided on the moving body (2) so as to face the groove (31). 32), two to four bearing races (33) arranged vertically above and below, and a plurality of rolling elements (34) rotatably arranged between the bearing races (33); An arc-shaped concave surface (31) is formed at both corners of each concave groove (31, 32).
a, 32a) and an arc-shaped convex surface (33a) is formed on a contact surface of the bearing race (33) with the arc-shaped concave surface (31a, 32a) to form the arc-shaped concave surface (31a, 32a). The linear actuator according to claim 1, wherein a radius of curvature is equal to or slightly larger than a radius of curvature of the arc-shaped convex surface.