JP2015001258A - Actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an actuator capable of preventing condensation in a housing.SOLUTION: An actuator 10 is composed of an actuator body 11 and a release pipe 18. The actuator body 11 is equipped with a motor unit 50, a ball screw shaft 70, a slide portion 60 provided with a ball screw nut 62, a rod 12 moving forward/backward in an axial direction, and a housing 20. The housing 20 is formed with an internal space R1 in which the motor unit 50, the ball screw shaft 70, and the slide portion 60 are water-tightly protected while a part of the rod 12 projects. The housing 20 is equipped with an inlet and outlet port 40a for keeping the inner pressure of the internal space R1 equal to the outside air pressure. Connection of the release pipe 18 to the inlet and outlet port 40a of the housing 20 causes outside air to be unlikely to enter the housing 20.

Description

  The present invention relates to an actuator that can prevent dew condensation inside an actuator housing.

  In the rod-type actuator, for example, the rod fixed to the slide portion moves forward and backward based on the rotational motion of the motor. Thereby, an arbitrary tool attached to the tip of the rod performs various operations such as pressing the workpiece to be worked (see, for example, Patent Document 1).

  The actuator described in Patent Document 1 is used in various environments. For example, an actuator may be used in a factory that manufactures processed foods or a factory that performs machining. In this case, cooling water for cooling the processed food or machine oil used in machining may be applied to the actuator. When a large amount of working liquid such as cooling water or machine oil is applied, there is a risk that the working liquid may enter the actuator from the gap between the members constituting the housing of the actuator.

  With respect to this problem, in the actuator described in Japanese Patent Application No. 2012-193195, a seal member is interposed between the members constituting the housing. Thereby, it is possible to prevent the working liquid from entering the actuator from the gap between the members of the housing. As a result, waterproofness and dripproofness can be improved.

  Further, in the actuator, the sealability of the internal space of the actuator is enhanced by the intervention of the seal member. As a result, when the rod moves back and forth, the internal pressure of the internal space of the actuator changes with a change in the volume of the internal space of the actuator. As a result, the smooth movement of the rod may be hindered. For this reason, the actuator is provided with an intake / exhaust port.

Japanese Patent No. 4918234

  Air is taken into the actuator described in Japanese Patent Application No. 2012-193195 from the intake / exhaust port as the internal pressure changes. If a large amount of cooling water or machine oil is applied to the actuator in a state where air having a relatively high humidity is taken in, the air inside the actuator is cooled. This may cause condensation in the actuator. When condensation occurs, the component parts of the actuator such as the encoder are adversely affected by moisture generated by the condensation, and the smooth movement of the slide part and the rod may be hindered.

  The present invention has been made under the above-described circumstances, and an object thereof is to provide an actuator that can prevent dew condensation inside the actuator.

In order to achieve the above object, an actuator according to the first aspect of the present invention provides:
A motor including a rotating shaft; a screw shaft that rotates together with the rotating shaft; a moving body that includes a nut that converts a rotational motion of the screw shaft into a linear motion; and a rod that is fixed to the moving body and moves forward and backward in the axial direction An internal space is formed in which the motor, the screw shaft, and the moving body are watertightly protected with a part of the rod protruding, and intake / exhaust for keeping the internal pressure of the internal space equal to the external pressure A housing comprising a mouth, and an actuator body comprising:
One end portion is connected to the intake / exhaust port of the housing, and the other end portion has an open pipe opened to the outside.

  The volume of the open tube may be larger than the volume of the internal space of the housing.

  The open pipe may be provided with an air reservoir.

An actuator according to a second aspect of the present invention includes a motor including a rotation shaft, a screw shaft that rotates together with the rotation shaft, a moving body including a nut that converts the rotational motion of the screw shaft into linear motion, and the movement A rod fixed to the body and moving forward and backward in the axial direction; and an internal space in which the motor, the screw shaft, and the movable body are protected in a watertight manner in a state in which a part of the rod protrudes. A housing having an intake / exhaust port for keeping the internal pressure equal to the external pressure, and an actuator body comprising:
One end is connected to an intake / exhaust port of the housing, and the other end is connected to an air reservoir.

  The volume of the air reservoir may be larger than the volume of the internal space of the housing.

The housing of the actuator according to the first aspect and the second aspect is:
A housing body having a front opening formed at an end on the front side;
A front cover for supporting the rod slidably and closing the front opening,
The front cover may include a rod sealing member for watertight sealing between the front cover and the rod.

  The front cover may include a front cover sealing member for watertightly sealing the housing body.

A rear opening is formed at the rear end of the housing body,
The housing includes a rear cover that closes the rear opening,
The rear cover may include a rear cover sealing member for watertight sealing between the housing body and the rear cover.

  According to the present invention, condensation inside the actuator can be prevented.

It is a perspective view of an actuator concerning a 1st embodiment of the present invention. It is sectional drawing of an actuator. It is a disassembled perspective view of an actuator main body. It is a perspective view (the 1) of a housing body. It is a perspective view (the 2) of a housing main body. It is sectional drawing of the front side edge part vicinity of an actuator main body. It is a disassembled sectional view of the vicinity of the front side end of the actuator body. It is a rear view of a front cover. It is sectional drawing of the rear side edge part vicinity of an actuator main body. It is a front view of a rear cover. It is sectional drawing, such as a slide part. It is a perspective view, such as a slide part. It is BB sectional drawing of FIG. It is AA sectional drawing of FIG. It is a side view for demonstrating an open pipe. It is sectional drawing (the 1) for demonstrating operation | movement of an actuator. It is sectional drawing (the 2) for demonstrating operation | movement of an actuator. It is a side view for explaining operation of an actuator (the 1). It is a side view (the 2) for demonstrating operation | movement of an actuator. It is a side view of an actuator concerning a modification. It is a side view of the actuator which concerns on 2nd Embodiment of this invention.

  Hereinafter, an actuator 10 according to a first embodiment of the present invention will be described with reference to FIGS. The XY plane in the figure is a horizontal plane, and the direction of the Z axis in the figure is the vertical direction.

  As shown in FIGS. 1 and 2, the actuator 10 is a rod-type actuator having a rod 12 that moves forward and backward in the Y-axis direction. The actuator 10 is a waterproof actuator in which the internal space R1 of the housing 20 is protected in a watertight manner. The actuator 10 includes an actuator body 11 and an open tube 18.

  One end of the open pipe 18 is connected to the housing 20 of the actuator body 11 and the other end 19 is released to the outside. The open pipe 18 is a hose having flexibility, and is drawn out to a position where no working liquid is applied.

  As shown in FIG. 3, the actuator body 11 includes a motor unit 50, a slide part 60 (moving body), a ball screw shaft 70, a base 80, a front side bearing, in addition to the rod 12 and the housing 20 described above. It has a unit 90A and a rear side bearing unit 90B.

  As shown in FIG. 2, the rod 12 is a cylindrical member having a hole formed therein, and is made of, for example, stainless steel. Further, the outer peripheral surface of the rod 12 is subjected to hard chrome plating. At the end of the rod 12 on the -Y side, a tip fitting M having an external thread formed on the outer periphery is screwed and fixed.

  The housing 20 is formed with an internal space R1 that is watertightly protected. The housing 20 is a member that supports the rod 12 and protects the motor unit 50, the slide portion 60, the ball screw shaft 70, and the like in a watertight manner in a state in which a part of the rod 12 protrudes. As shown in FIG. 3, the housing 20 includes a housing body 21, a front cover 30, and a rear cover 40.

  As shown in FIG. 4, the housing body 21 is a cylindrical member whose longitudinal direction is the Y-axis direction. The housing body 21 is formed, for example, by extruding aluminum. A front opening 21 a is formed at an end of the housing body 21 on the front side (−Y side). The front end face 22 of the housing body 21 is configured in a plane parallel to the XZ plane. A screw hole 22a is formed in the end face 22 on the front side. In the present embodiment, the number of screw holes 22a is four.

  As shown in FIG. 5, a rear opening 21 b is formed at the rear side (+ Y side) end of the housing body 21. The rear end face 23 of the housing body 21 is configured in a plane parallel to the XZ plane. A screw hole 23 a is formed in the rear end face 23. In the present embodiment, the number of screw holes 23a is four.

  The top plate portion 24 of the housing main body 21 is formed with a tool through hole 24a penetrating in the Z-axis direction. A cap 24b is detachably attached to the tool through hole 24a.

  As shown in FIGS. 4 and 5, the bottom plate portion 25 of the housing body 21 is formed with a bolt through hole 25 a penetrating in the Z-axis direction. In addition, two mounting grooves 25 b are formed on the lower surface (the surface on the −Z side) of the bottom plate portion 25. The mounting groove 25 b is formed along the longitudinal direction of the housing body 21. The mounting groove 25b is used for mounting on the installation target equipment or installation base of the actuator 10.

  The front cover 30 is a member that closes the front opening 21 a of the housing body 21 as shown in FIGS. 6 and 7. The front cover 30 includes rod seal members 31 and 32 for protecting the inner space R1 of the housing 20 in a watertight manner, a front cover seal member 33, and a soft wiper 34. Further, the front cover 30 is formed with a rod through hole 30a for allowing the rod 12 to pass therethrough. An annular groove 35 for fitting the rod seal member 31 is formed on the inner peripheral surface of the rod through hole 30a. A recess 36 for fitting the rod seal member 32 is formed in the opening on the −Y side of the rod through hole 30a. On the end surface of the front cover 30 on the + Y side, a grease retaining recess 37 is formed. The grease reservoir convex portion 92 of the front bearing unit 90 </ b> A is fitted into the grease reservoir concave portion 37 via a grease reservoir seal member 93. A grease supply path 39a is formed between the grease reservoir concave portion 37 and the grease reservoir convex portion 92 (see FIG. 6).

FIG. 8 is a rear view of the front cover 30. As shown in FIG. 8, a groove 38 is formed on the + Y side end face (front face in FIG. 8) of the front cover 30. Further, the front cover 30 is formed with a bolt through hole 30b penetrating in the Y-axis direction. In the present embodiment, the number of bolt through holes 30b formed in the front cover 30 is four corresponding to the number of screw holes 22a in the housing body 21, as can be seen from FIG. . Bolts 13 for fixing the front cover 30 to the housing body 21 are inserted into the bolt through holes 30b. The bolt 13 inserted into the bolt through hole 30 b is screwed into the screw hole 22 a of the housing body 21. As a result, the front cover 30 is fixed to the housing body 21.

  As shown in FIGS. 6 and 7, the rod sealing member 31 is fitted in the groove 35 of the front cover 30 to seal the space between the front cover 30 and the rod 12 in a watertight manner. The cross-sectional shape of the rod sealing member 31 is X-shaped in the present embodiment. The rod sealing member 31 is made of rubber, for example. The surface of the rod sealing member 31 is DLC (Diamond Like Carbon) coated and cured.

The rod sealing member 32 is fitted in the recess 36 of the front cover 30 to seal the space between the front cover 30 and the rod 12 in a watertight manner. The rod seal member 32 is, for example, a substantially annular dust seal in which a protruding portion 32a protruding in the −Y direction is formed. The protrusion 32 a of the rod sealing member 32 is formed so as to contact the outer peripheral surface of the rod 12. This prevents water and dust outside the actuator 10 from entering the internal space R1 of the housing 20 as the rod 12 moves forward and backward. The rod seal member 32 includes a rubber seal member main body and a metal portion 32b embedded in the seal member main body. The seal member main body of the rod seal member 32 is made of rubber, for example. The surface of the rod sealing member 32 is DLC (Diamond Like Carbon) coated and cured. The rod sealing member 32, together with the rod sealing member 31, prevents intrusion of foreign matter, water droplets, etc. into the internal space R <b> 1 of the housing 20.

  The front cover sealing member 33 is fitted in the groove 38 of the front cover 30 to seal the space between the front cover 30 and the housing body 21 in a watertight manner. The front cover sealing member 33 is, for example, an O-ring. The front cover sealing member 33 prevents foreign matter and water droplets from entering the internal space R1 of the housing 20.

  The soft wiper 34 is fitted into a recess formed at the + Y side end of the rod seal member 32. The soft wiper 34 is made of felt, for example. The soft wiper 34 is impregnated with grease, for example, to prevent the wear powder generated in the internal space R <b> 1 of the housing 20 from flowing out to the outside or to supply grease to the outer peripheral surface of the rod 12.

Further, the front cover 30 includes a grease nipple 39. The grease nipple 39 is a member for injecting grease for smoothly moving the rod 12. The grease nipple 39 is attached by being press-fitted into the grease nipple attachment hole 30 c of the front cover 30. The grease nipple mounting hole 30c communicates with the rod through-hole 30a through grease supply passages 39a and 39b. The grease nipple 39 includes a main body portion having a through hole, a spring inserted into the through hole, and a ball urged upward (+ Z direction) by the spring. When the ball is urged upward by the spring, the opening of the grease nipple 39 is closed.

  When injecting grease into the grease nipple 39, the user of the actuator 10 first connects a grease gun for supplying the grease to the grease nipple 39. Then, when grease flows from the grease gun, injection of grease is started. Then, the ball moves downward (−Z direction) against the urging force of the spring. Thereby, the grease passes through the grease supply passages 39a and 39b and is supplied to the outer peripheral surface of the rod 12.

  As shown in FIG. 9, the rear cover 40 is a member that closes the rear opening 21 b of the housing body 21. The rear cover 40 has a rear cover sealing member 41 for keeping the inside of the housing 20 watertight. A groove 42 for fitting the rear cover seal member 41 is formed on the end surface of the rear cover 40 on the −Y side. In addition, an intake / exhaust port 40 a that communicates the internal space R <b> 1 of the housing 20 and the outside of the actuator body 11 is formed on the + Y side surface of the rear cover 40.

FIG. 10 is a front view of the rear cover 40. As shown in FIG. 10, the rear cover 40 is formed with a bolt through hole 40 b that penetrates in the Y-axis direction. In the present embodiment, the number of bolt through holes 40b formed in the rear cover 40 is four corresponding to the number of screw holes 23a of the housing body 21 shown in FIG. As shown in FIG. 3, bolts 14 for fixing the rear cover 40 to the housing body 21 are inserted into the bolt through holes 40 b. The bolt 14 inserted into the bolt through hole 40 b is screwed into the screw hole 23 a of the housing body 21. Thereby, the rear cover 40 is fixed to the housing body 21.

  As shown in FIG. 9, the rear cover seal member 41 is fitted in the groove 42 of the rear cover 40 to seal the space between the rear cover 40 and the housing body 21 in a watertight manner. The rear cover sealing member 41 is, for example, an O-ring. The rear cover sealing member 41 prevents foreign matter and water droplets from entering the internal space R1 of the housing 20.

  The rear cover 40 includes an intake / exhaust port 43 attached to the intake / exhaust port 40a. The intake / exhaust port 40a and the intake / exhaust port 43 are used to keep the internal pressure of the internal space R1 of the housing 20 equal to the external air pressure by communicating with the internal space R1 from the outside of the housing 20. An open pipe 18 is connected to the intake / exhaust port 43.

  In addition, a cable through hole 40c is formed on the surface of the rear cover 40 on the + Y side. The actuator cable 54 is passed through the cable through hole 40c.

  As shown in FIG. 9, the motor unit 50 includes a motor main body 51, an encoder 52, a motor bracket 53, and an actuator cable 54.

  The motor body 51 includes, for example, an output shaft 51a (rotating shaft), a rotor, a stator, a motor case 51b, and the like. Electric power from a power source is supplied to the motor main body 51 via the actuator cable 54. When electric power is supplied to the motor main body 51, the rotor of the motor main body 51 rotates. This rotational motion of the rotor is output to the output shaft 51a. A coupling 55 (joint member) is attached to the tip of the output shaft 51a.

  The encoder 52 has, for example, a code wheel, an optical sensor, an encoder cover for storing these, and the like. The code wheel rotates together with the output shaft 51a. The optical sensor emits illumination light to the code wheel, receives illumination light reflected by the code wheel, and outputs a voltage signal corresponding to the intensity of the received illumination light. Thereby, the encoder 52 detects the rotation of the output shaft 51 a of the motor main body 51.

The motor bracket 53 is a member that supports the motor case 51b of the motor body 51 to the rear side bearing unit 90B. The motor bracket 53 is fixed to the surface on the −Y side of the motor case 51b by, for example, a bolt. The motor bracket 53 is formed with a through hole 53a penetrating in the Y-axis direction. An output shaft 51a protruding in the −Y direction from the motor case 51b is disposed in the through hole 53a. A screw hole 53 b is formed in the upper surface (+ Z side surface) of the motor bracket 53. A set screw 57 is screwed into the screw hole 53b. The lower end of the set screw 57 presses the upper surface of the rear side bearing unit 90B, whereby the motor bracket 53 is fixed to the rear side bearing unit 90B. It should be noted that the screwing operation of the set screw 57 into the screw hole 53b is performed by removing the cap 24b from the tool through hole 24a formed in the housing body 21 and using a tool for screwing the set screw 57 into the tool through hole 24a. It is done while inserting into.

  As shown in FIGS. 11 and 12, the slide unit 60 (moving body) is a member that moves in both the + Y direction and the −Y direction together with the rod 12 when the rod 12 is fixed. The slide part 60 includes a slide part main body 61, a ball screw nut 62, and a rolling element storage unit 63.

  The slide part main body 61 is a substantially rectangular parallelepiped member made of metal, for example. The slide part body 61 is formed with a through hole 61a penetrating in the Y-axis direction. On the inner peripheral surface of the through hole 61a of the slide portion main body 61 in the vicinity of the opening on the -Y side, a female screw portion is formed. On the other hand, a male thread portion is formed on the outer peripheral surface of the rod 12 near the end on the + Y side. The rod 12 is fixed to the slide portion main body 61 by the male screw portion of the rod 12 being screwed into the female screw portion of the through hole of the slide portion main body 61.

  The ball screw nut 62 is disposed on the outer periphery of the ball screw shaft 70. The ball screw nut 62 is fitted into the ball screw shaft 70 via a plurality of rolling elements. When the rolling element rolls, the rotational motion of the ball screw shaft 70 is smoothly converted into the linear motion of the ball screw nut 62. Further, the ball screw nut 62 is inserted from the + Y side of the through hole 61a formed in the slide portion main body 61 and is fixed by a bolt or the like.

  The rolling element storage unit 63 is fixed to the lower surface (the surface on the −Z side) of the slide portion main body 61. Inside the rolling element storage unit 63, as shown in FIG. 13, a rolling element circulation path 63a is formed. A plurality of rolling elements B1 are arranged in the rolling element circulation path 63a.

  As shown in FIG. 2, the ball screw shaft 70 includes a ball screw shaft main body 71 having an outer peripheral surface configured as a spiral ball screw surface, and a small-diameter portion formed at the end of the ball screw shaft main body 71 on the + Y side. 72 and a connecting member 73 fitted and fixed in the small diameter portion 72. As shown in FIG. 9, the rear bearing unit 90 </ b> B and the coupling 74 (joint member) are attached to the connection member 73.

  The coupling 74 is fixed to the connection member 73 of the ball screw shaft 70 by, for example, a screw for preventing rotation. The coupling 74 is formed in a shape that fits into the coupling 55 attached to the tip of the output shaft 51 a of the motor unit 50. When the coupling 74 is fitted to the coupling 55, the ball screw shaft 70 rotates together with the output shaft 51a. Thereby, the rotational motion of the output shaft 51a is transmitted to the ball screw shaft 70.

As shown in FIGS. 2 and 3, the base 80 is a member whose longitudinal direction is the Y-axis direction. As shown in FIG. 13, the base 80 includes a bottom plate portion 81 and side wall portions 82 </ b> R and 82 </ b> L formed on both sides of the bottom plate portion 81. The base 80 is formed, for example, by extruding aluminum. Concave portions are formed in the −X side surface of the side wall portion 82R and the + X side surface of the side wall portion 82L, respectively. Guide rails 83R and 83L having a longitudinal direction in the Y-axis direction are attached to the recess. Grooves are formed in the −X side surface of the guide rail 83R and the + X side surface of the guide rail 83L, respectively. The groove portions are formed to face each other, and the inner surface of the groove portion is configured as a substantially curved surface.

14 is a cross-sectional view taken along the line AA in FIG. As shown in FIG. 14, a screw hole 80 a is formed on the lower surface (the surface on the −Z side) of the base 80. The number of screw holes 80 a is three corresponding to the number of bolt through holes 25 a in the bottom plate portion 25 of the housing body 21. The base 80 is fixed to the housing body 21 by bolts 88. Specifically, the bolt 88 is inserted into the bolt through-hole 25a from the lower side (−Z side) of the housing main body 21 through a disc-shaped seal member 89 having a hole formed in the center. Then, the bolt 88 is screwed into the screw hole 80 a of the base 80. The seal member 89 is made of an elastic material and seals between the head of the bolt 88 and the bolt through hole 25a in a watertight manner.

  Moreover, as shown in FIG. 13, the slide part 60 is attached to the base 80 via several rolling element B1. As the rolling element B1 rolls on the guide rails 83R and 83L, the slide portion 60 smoothly moves in both the + Y direction and the −Y direction in the Y-axis direction.

The front bearing unit 90A is fixed to the front side (−Y side) of the base 80, as shown in FIGS. A through hole for passing the rod 12 is formed in the front bearing unit 90A, and an oilless bearing 91 is disposed on the inner peripheral surface of the through hole. The oilless bearing 91 supports the rod 12 so as to be movable back and forth in the Y-axis direction. The front bearing unit 90A is formed with a grease retaining convex portion 92 protruding in the -Y direction. The grease retaining convex portion 92 is fitted with a grease retaining seal member 93 made of an O-ring. The grease retaining seal member 93 is used to prevent the grease from flowing out into the internal space R <b> 1 of the housing 20 from the grease supply path 39 a formed by the grease retaining convex portion 92 and the grease retaining concave portion 37.

  As shown in FIG. 9, the rear side bearing unit 90B includes a ball bearing 95, a bearing housing, and a bearing retainer. The rear-side bearing unit 90B has a through hole for inserting the ball screw shaft 70, and a ball bearing 95 is disposed on the inner peripheral surface of the through hole. The ball bearing 95 is fitted from the −Y side of the through hole and is pressed by the bearing pressing portion. The bearing retainer is fixed to the bearing housing by bolts or the like. The ball screw shaft 70 is rotatably supported by the ball bearing 95.

The actuator 10 configured as described above is of a waterproof specification in which the inner space R1 of the housing 20 is watertightly protected by the rod seal members 31, 32, the front cover seal member 33, and the rear cover seal member 41. is there. For this reason, it can be used in a high humidity environment such as a factory for manufacturing processed foods or a factory for machining. In this case, the end 19 of the open pipe 18 is drawn to a place where the cooling water for cooling the processed food and the machine oil used in the machining are not covered. Further, as shown in FIG. 15, the volume C1 inside the open pipe 18 (= length L1 of the open pipe 18 × inner diameter D1 of the open pipe 18) is larger than the volume C2 of the internal space R1 of the housing 20. Yes.
The internal volume C1 of the open pipe 18 may be larger than the volume C2 of the internal space R1 of the housing 20, but if the length L1 is reduced and the internal diameter D1 is relatively increased, the open pipe 18 is increased. Becomes hard and unusable. The volume C1 inside the open pipe 18 is preferably 1.5 times the volume C2 of the internal space R1 of the housing 20.

  The operation of the actuator 10 configured as described above will be described with reference to FIGS. 16A, 16B, 17, and 18. FIG.

  First, when power is supplied to the motor unit 50, as shown in FIG. 17A, the output shaft 51a of the motor unit 50 rotates (forward rotation) in a predetermined direction. When the output shaft 51a rotates in a predetermined direction, the ball screw shaft 70 connected to the output shaft 51a rotates (forward rotation) together with the output shaft 51a.

  When the ball screw shaft 70 rotates, as shown in FIG. 16B, the ball screw nut 62 linearly moves in the −Y direction, for example, with the rotational motion of the ball screw shaft 70. When the ball screw nut 62 moves in the −Y direction, the slide portion 60 fixed to the ball screw nut 62 also moves in the −Y direction together with the ball screw nut 62.

  When the slide part 60 moves in the −Y direction, the rod 12 fixed to the slide part 60 also moves in the −Y direction together with the slide part 60. Thereby, the tip metal fitting M attached to the tip of the rod 12 moves in the -Y direction. At this time, when the workpiece W is disposed on the distal end side of the rod 12, the rod 12 (specifically, the distal end fitting M of the rod 12) presses the workpiece W.

At this time, since the internal space R1 of the housing 20 is kept watertight, as shown in FIG. 17, the internal capacity of the internal space R1 increases as the rod 12 moves in the −Y direction.
Then, the air outside the actuator 10 flows into the internal space R <b> 1 of the housing 20 through the open pipe 18. Thereby, the internal pressure of the internal space R1 is kept equal to the external pressure. As a result, the slide part 60 and the rod 12 move smoothly without being affected by changes in the internal pressure of the internal space R1.

  The volume C1 inside the open pipe 18 (= length L1 of the open pipe 18 × the inner diameter D1 of the open pipe 18) is larger than the volume C2 of the internal space R1 of the housing 20. For this reason, even when the rod 12 moves forward and backward, it is difficult for external air to flow into the internal space R <b> 1 of the housing 20 through the open pipe 18.

  Thus, the movement of the rod 12 and the tip fitting M in the −Y direction is completed.

  Next, when the output shaft 51a of the motor unit 50 rotates (reverses) in a direction opposite to a predetermined direction, the ball screw shaft 70 connected to the output shaft 51a also outputs as shown in FIGS. 16A and 16B. It rotates (reverses) in the opposite direction together with the shaft 51a.

  When the ball screw shaft 70 rotates, the ball screw nut 62 linearly moves in the + Y direction as the ball screw shaft 70 rotates. When the ball screw nut 62 moves in the + Y direction, the slide portion 60 fixed to the ball screw nut 62 also moves in the + Y direction together with the ball screw nut 62.

  When the slide part 60 moves in the + Y direction, the rod 12 fixed to the slide part 60 also moves in the + Y direction together with the slide part 60. As a result, the tip fitting M attached to the tip of the rod 12 moves in the + Y direction, and the rod 12 (specifically, the tip fitting M of the rod 12) is separated from the workpiece W.

At this time, since the internal space R1 of the housing 20 is kept watertight, as shown in FIG. 18, the internal capacity of the internal space R1 decreases as the rod 12 moves in the + Y direction.
Then, the air in the internal space R 1 of the housing 20 of the actuator 10 flows out of the actuator 10 through the open pipe 18. Thereby, the internal pressure of the internal space R1 is kept equal to the external pressure. As a result, the slide part 60 and the rod 12 move smoothly without being affected by changes in the internal pressure of the internal space R1.

  Thus, the movement of the rod 12 and the tip fitting M in the + Y direction is completed, and the rod 12 and the tip fitting M are returned to the initial positions.

As described above, in the actuator 10 according to the first embodiment, the internal volume C1 of the open pipe 18 (= length L1 of the open pipe 18 × inner diameter D1 of the open pipe 18) is the internal space of the housing 20. It is larger than the volume C2 of R1. For this reason, even when the rod 12 moves forward and backward, it is difficult for external air to flow into the internal space R <b> 1 of the housing 20 through the open pipe 18.
Thereby, an increase in the humidity of the air in the internal space R1 can be suppressed, and as a result, condensation in the internal space R1 can be prevented.

  On the other hand, in the case of an actuator in which the open pipe 18 is not connected to the actuator body 11, air containing moisture flows from the intake / exhaust port 40a as the rod 12 moves. When liquid is applied to the actuator or when the ambient temperature around the actuator is low, the temperature of the internal space R1 of the housing 20 decreases. As a result, the air in the internal space R <b> 1 is cooled, and condensation occurs in the internal space R <b> 1 of the housing 20. When dew condensation occurs, the component parts of the actuator 10 such as the encoder 52 are adversely affected by moisture generated by the dew condensation, and the smooth movement of the slide unit 60 and the rod 12 may be hindered.

  However, in the actuator 10 according to the first embodiment, it is difficult for outside air to flow into the internal space R1 of the housing 20 through the open pipe 18. For this reason, even if the temperature of the internal space R1 of the housing 20 decreases, condensation in the internal space R1 of the housing 20 can be prevented. As a result, the components of the actuator 10 such as the encoder 52 caused by moisture caused by condensation can prevent adverse effects. As a result, the movement of the slide part 60 and the rod 12 is not inhibited.

In the actuator 10 according to the first embodiment, the rear cover 40 includes a rear cover sealing member 41 for watertight sealing between the housing body 21 and the rear cover 40. For this reason, air containing moisture does not flow into the internal space R1 of the housing 20, and as a result, dew condensation in the internal space R1 can be prevented.

    Further, in the actuator 10 according to the first embodiment, the front cover 30 includes rod sealing members 31 and 32 for watertight sealing between the front cover 30 and the rod 12. For this reason, air containing moisture does not flow into the internal space R1 of the housing 20, and as a result, dew condensation in the internal space R1 can be prevented.

  Further, in the actuator 10 according to the first embodiment, the front cover 30 includes a front cover sealing member 33 for watertight sealing between the front cover 30 and the housing body 21. For this reason, air containing moisture does not flow into the internal space R1 of the housing 20, and as a result, dew condensation in the internal space R1 can be prevented.

  In addition, the end 19 of the open pipe 18 connected to the intake / exhaust port 43 is pulled out to a position where the working liquid is not applied, thereby preventing the working liquid from entering and the internal pressure of the internal space of the housing 20. Is kept equal to the external pressure. As a result, the rod 12 moves forward and backward smoothly.

  The first embodiment of the present invention has been described above, but the present invention is not limited to the above-described embodiment and the like.

  In the first embodiment, the housing 20 includes two rod sealing members 31 and 32 for watertight sealing between the rod 12 and the front cover 30. However, the present invention is not limited to this, and one rod sealing member may be provided, or three or more rod sealing members may be provided.

  In the first embodiment, the volume C1 inside the open pipe 18 (= length L1 of the open pipe 18 × inner diameter D1 of the open pipe 18) is larger than the volume C2 of the internal space R1 of the housing 20. . However, in the first embodiment, it is difficult to shorten the length of the open tube 18. Therefore, as shown in FIG. 19, an air reservoir 100 may be provided in the middle of the open pipe 18 to shorten the length of the open pipe 12.

Further, as in the first embodiment, when it is difficult to draw the end portion 19 of the open pipe 18 to a position where the working liquid is not applied. As shown in FIG. 20, the air reservoir 100 having an internal volume larger than the volume C <b> 2 of the internal space R <b> 1 of the housing 20 may be connected to the intake / exhaust port 43 through the connection pipe 101.
In this case, since the internal air of the housing 20 circulates inside the air reservoir 100 and the actuator 10, the internal pressure of the internal space R1 can be kept constant.

  Various embodiments and modifications can be made to the present invention without departing from the broad spirit and scope of the present invention. The above-described embodiments are for explaining the present invention, and do not limit the scope of the present invention.

10, 10A, 10B Actuator 11 Actuator body 12 Rod 13, 14 Bolt 18 Open tube

DESCRIPTION OF SYMBOLS 19 End part 20 Housing 21 Housing main body 21a Front opening part 21b Rear opening part 22, 23 End surface 22a, 23a Screw hole 24 Top plate part 24a Tool through-hole 24b Cap 25 Bottom plate part 25a Bolt through-hole 25b Mounting groove 30 Front Cover 30a Rod through hole 30b Bolt through hole 30c Grease nipple mounting hole 31, 32 Rod seal member 32a Protruding portion 32b Metal portion 33 Front cover seal member 34 Soft wiper 35 Groove 36 Recess 37 Grease reservoir recess 38 Groove 39 Grease nipples 39a, 39b Grease supply path 40 Rear cover 40a Air intake / exhaust port 40b Bolt through hole 40c Cable through hole 41 Rear cover sealing member 42 Groove 43 Air intake / exhaust port 50 Motor unit (motor)
51 Motor body 51a Output shaft (rotary shaft)
51b Motor case 52 Encoder 53 Motor bracket 53a Through hole 53b Screw hole 54 Actuator cable 55 Coupling 57 Set screw 60 Slide part (moving body)
61 Slide body 61a Through hole 62 Ball screw nut (nut)
63 Rolling body storage unit 63a Rolling body circulation path 70 Ball screw shaft (screw shaft)
71 Ball screw shaft body 72 Small diameter part 73 Connection member 74 Coupling 80 Base 80a Screw hole 81 Bottom plate part 82R, 82L Side wall part 83R, 83L Guide rail 88 Bolt 89 Seal member 90A Front side bearing unit 90B Rear side bearing unit 91 Oilless Bearing 92 Grease reservoir convex portion 93 Grease reservoir seal member 95 Ball bearing 100 Air reservoir B1 Rolling element M Tip fitting R1, R2 Internal space W Work C1, C2, C3 Capacity L1, L2 Length D1, D2 Inner diameter

Claims (8)

A motor including a rotating shaft, a screw shaft that rotates together with the rotating shaft, and a moving body including a nut that converts a rotational motion of the screw shaft into a linear motion;
An internal space is formed in which the motor, the screw shaft, and the moving body are protected in a water-tight manner with a rod fixed to the moving body and moving forward and backward in the axial direction, and a part of the rod protruding. A housing having an intake / exhaust port for keeping the internal pressure equal to the external pressure, and an actuator body comprising:
An actuator comprising an open tube having one end connected to the intake / exhaust port of the housing and the other end open to the outside.   The actuator according to claim 1, wherein a volume of the open pipe is larger than a volume of the internal space of the housing.   The actuator according to claim 3, wherein an air reservoir is provided in the open pipe. A motor including a rotating shaft, a screw shaft that rotates together with the rotating shaft, and a moving body including a nut that converts a rotational motion of the screw shaft into a linear motion;
A rod fixed to the moving body and moving forward and backward in the axial direction, and an internal space in which the motor, the screw shaft, and the moving body are protected in a watertight manner with a part of the rod projecting are formed, and the internal space A housing having an intake / exhaust port for keeping the internal pressure equal to the external pressure, and an actuator body comprising:
An actuator comprising a connecting pipe having one end connected to the intake / exhaust port of the housing and the other end connected to an air reservoir.   The actuator according to claim 4, wherein a volume of the air reservoir is larger than a volume of the internal space of the housing. The housing is
A housing body having a front opening formed at an end on the front side;
A front cover for supporting the rod slidably and closing the front opening,
The actuator according to any one of claims 1 to 5, wherein the front cover includes a rod sealing member for watertightly sealing between the front cover and the rod.   The actuator according to claim 6, wherein the front cover includes a front cover sealing member for watertight sealing between the front cover and the housing body.   A rear opening is formed at an end of the housing body on the rear side, the housing includes a rear cover that closes the rear opening, and the rear cover seals water tightly with the housing body. The actuator according to claim 6, further comprising a rear cover sealing member.