JP2006083942A - Actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an actuator usable under environment subject to much dust and directly in a water jet flow without problems. <P>SOLUTION: The actuator comprises a hollow member 27, a screw 25 stored and arranged on the inner peripheral side of the hollow member 27 and adapted to be rotationally driven, a nut 29 stored and arranged on the inner peripheral side of the hollow member 27 and threaded to the screw 25, a piston portion 41 stored and arranged on the inner peripheral side of the hollow member 27 and fixed to the nut, a driving side magnet portion 60 provided on the piston portion 41, a slider portion 71 movably arranged on the outer peripheral side of the hollow member 27 in its rotation restricted state, and a driven side magnet portion 82 provided on the slider portion. The nut and the piston portion are moved in a proper direction by rotationally driving the screw 25. Thus, the slider portion is moved in the same direction by the operation of the driving side magnet portion on the driven side magnet portion. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to an actuator, and more particularly, to an actuator devised so that it can be used without any trouble even in a dusty environment or an environment where water is directly jetted.

  A conventional actuator is generally configured as follows. First, there is a housing, and a ball screw is rotatably accommodated in the housing. For example, the ball screw is connected to a rotation shaft of a servo motor via a coupling, and is rotated by the servo motor. A ball nut is screwed onto the ball screw in a state where its rotation is restricted. A slider is fixed to the ball nut, and an arbitrary device is mounted on the slider.

  Then, the ball screw is rotated in the same direction by rotationally driving the servo motor in an appropriate direction. With this rotation of the ball screw, the ball nut screwed in a state where the rotation is regulated moves in an arbitrary direction, so that the slider fixed to the ball nut and the device mounted on the ball nut are moved. It moves by a predetermined amount in the same direction.

By the way, in this type of actuator, since the slider fixed to the ball nut needs to be exposed to the outside of the housing, the housing has an opening formed in a slit shape along the moving direction of the slider. . Therefore, dust, water droplets, etc. will enter the inside of the housing through this opening. On the contrary, there is a concern that grease, oil, or the like adhering to the ball screw or ball nut may be scattered and outflowed to the outside through the opening.

Therefore, processing such as making the opening as small as possible, forming a labyrinth structure made of a protective cover or the like in the opening to make the gap as small as possible, or attaching a bellows to the opening, Prevents dust and water droplets from entering the inside of the housing, and prevents grease and oil adhering to the ball screw and ball nut from splashing and flowing outside through the opening. It was like that.
In addition to the above measures, for example, the inside of the housing is brought into a negative pressure state by evacuation, so that grease, oil, etc. adhering to the ball screw or ball nut scatter and flow out to the outside through the opening. It was also done to prevent this. Conversely, pressurizing the inside of the housing has also prevented dust and water droplets from entering the inside of the housing through the opening.

The various measures will be described with specific examples.
First, there is a case where the actuator is used in a food machine of a food factory. In the case of this kind of food factory, various washings are performed, and it is expected that water droplets and the like at the time of such washing will enter the inside of the actuator used in the food machine through the opening. . Also, there is a concern that oil or grease applied to the ball screw or ball nut built in the actuator housing may be scattered outside through the opening or oil may leak and adhere to food. Is done. In such a case, as described above, a labyrinth structure made of a protective cover or the like is formed in the opening to reduce the gap as much as possible, or a process such as attaching a bellows to the opening is performed, and the opening is inserted through the opening. This prevents dust and water droplets from entering the inside of the housing, and prevents grease and oil from the ball screw and ball nut from splashing and flowing outside through the opening. It was.
In addition, when taking measures such as using expensive food grease or oil so that the human body will not be harmed even if some grease or oil flows outside and adheres to food. There was also.

Next, the case where an actuator is used for a packaging machine is mentioned. In an environment where this type of packaging machine is used, fine paper fibers, etc. are floating, and they enter the inside of the actuator through the opening and adhere to the oil in the lubrication part. There is concern over damage to the machine due to poor lubrication or contamination. Therefore, as described above, a labyrinth structure composed of a protective cover or the like is formed in the opening to make the gap as small as possible, or a process such as attaching a bellows to the opening is performed, and fine fibers etc. are passed through the opening. Is prevented from entering the inside of the housing.

The conventional configuration has the following problems.
First, even if a labyrinth structure composed of a protective cover or the like is formed in the opening to make the gap as small as possible or a bellows is attached to the opening, the opening is not completely closed. Therefore, the intrusion of dust and water droplets cannot be completely prevented, and even when there are no splashes or direct jets, etc., when the environmental humidity is high, the internal humidity is inevitably high, which may cause rusting. As a result, the use in a dusty environment or an environment in which water is directly jetted has a great restriction.
In addition, when a bellows or the like is used, there is a problem that the stroke becomes long due to the mating cost of the bellows, and there is a problem that the manufacturing cost increases because the machine is large and the bellows is expensive. there were.
In addition, the inside of the actuator can be sucked to prevent grease or oil from the ball screw or ball nut from splashing or flowing outside through the opening, or the inside of the actuator can be pressurized to open the opening. In the case of a method for preventing dust, water droplets and the like from entering the inside of the housing, there is a problem that the equipment for suction and pressurization becomes large and the manufacturing cost increases.

The present invention has been made on the basis of such points, and the object of the present invention is to be used without any trouble even in an environment where there is a lot of dust or where a direct jet of water is used. It is to provide a possible actuator.

  As prior applications for the present invention, there are, for example, Patent Document 1 and Patent Document 2.

Japanese Utility Model Publication No. 58-76804 Japanese Utility Model Publication No. 5-67866

In order to achieve the above object, an actuator according to claim 1 of the present invention includes a hollow member, a screw that is housed and disposed on the inner peripheral side of the hollow member and is driven to rotate, and a housing and disposed on the inner peripheral side of the hollow member. A nut that is screwed and arranged with respect to the screw, a piston portion that is housed and arranged on the inner peripheral side of the hollow member and is fixed to the nut, and a drive-side magnet portion that is provided on the piston portion; A magnetic thrust direction coupling mechanism is configured by a combination of a slider portion movably disposed on the outer peripheral side of the hollow member in a state where its rotation is restricted and a driving side magnet portion provided on the slider portion. A driven-side magnet portion, and by rotating and driving the screw, the nut and the piston portion are moved in appropriate directions, whereby the driven-side magnet portion and the driven-side magnet portion The slider portion is configured to move in the same direction by the action of a magnetic thrust direction coupling mechanism comprising:
According to a second aspect of the present invention, in the actuator according to the first aspect, the hollow member is made of a nonmagnetic material.
According to a third aspect of the present invention, in the actuator according to the first or second aspect of the present invention, the driven-side magnet portion is formed by coating or molding a resin on the surface of the magnet.
According to a fourth aspect of the present invention, there is provided the actuator according to the first aspect, wherein a magnetic rotational direction coupling mechanism is provided between the piston portion and the slider portion with the hollow member interposed therebetween. To do.
According to a fifth aspect of the present invention, in the actuator according to the fourth aspect, the magnetic rotational direction coupling mechanism includes an inner magnet for a magnetic rotational direction coupling mechanism provided in the piston portion, and the slider portion. The magnetic rotation direction coupling mechanism is provided with an outer magnet.
An actuator according to claim 6 is the actuator according to any one of claims 1 to 5, wherein the screw is a ball screw.
An actuator according to claim 7 is the actuator according to any one of claims 1 to 5, wherein the screw is a trapezoidal screw.

As described above, the actuator according to the present invention includes a hollow member, a screw that is housed and disposed on the inner peripheral side of the hollow member, and a rotationally driven screw, and a screw that is housed and disposed on the inner peripheral side of the hollow member. A nut screwed and arranged; a piston portion housed and arranged on the inner peripheral side of the hollow member and fixed to the nut; a driving magnet portion provided on the piston portion; and an outer periphery of the hollow member And a driven-side magnet portion that constitutes a magnetic thrust direction coupling mechanism by a combination of a slider portion movably arranged in a state where its rotation is restricted on the side, and the driving-side magnet portion provided on the slider portion; And the nut and the piston part are moved in an appropriate direction by rotating and driving the screw, whereby a magnet composed of the drive-side magnet part and the driven-side magnet part. Since the slider portion is configured to move in the same direction by the action of the pneumatic thrust direction coupling mechanism, first, all mechanical components including screws and nuts are accommodated and arranged in the hollow member. Since it is isolated, it can be used without any trouble even in the case of liquid droplets and direct jets.
In addition, since all machine components consisting of screws and nuts are housed and isolated in the hollow member, it is possible to prevent the internal oil and grease from flowing out to the outside. An actuator that can be used in a clean environment without polluting the environment can be provided.
Further, since it is not necessary to employ an expensive bellows or a complicated labyrinth mechanism as in the prior art, the processing cost can be reduced, and a slider type actuator having a dustproof and dripproof structure can be easily realized at a low cost.
Further, when the hollow member is made of a nonmagnetic material, the function of the magnetic thrust direction coupling mechanism can be made more accurate.
Further, when the driven magnet portion is formed by coating or molding a resin on the surface of the magnet, a rust prevention effect can be obtained.
In addition, when a magnetic rotational direction coupling mechanism is provided with the hollow member sandwiched between the piston portion and the slider portion, it is possible to restrict inadvertent rotation of the nut and the piston portion, For example, it is possible to prevent the slider portion from inadvertently moving due to the action of an external force.
As the screw, for example, a ball screw or a trapezoidal screw can be considered. Of course, it is not limited to them.

Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, there is a housing 1 first. The housing 1 has a substantially U-shaped cross section, and is composed of a bottom wall 3 and a pair of side walls 5 and 5. End members 7 and 7 are attached to both ends of the housing 1 in the longitudinal direction.
2 shows a state in which the housing 1 and the like are removed from FIG.

  A servo motor case 9 is attached to the outer side of the housing 1 and on the right side of the end member 7 in FIGS. As shown in FIG. 4, a servo motor 11 is built in the servo motor case 9. Cable take-out members 10 and 12 are attached to the right side of the servo motor case 9 in FIGS. A position detection mechanism 13 is attached to the right side of the servo motor 11 in FIG. The servo motor case 9 includes a cylindrical member 15 and end members 17 and 19 attached to both ends of the cylindrical member 15 as shown in FIG.

As shown in FIG. 4, a ball screw 25 is connected to the rotating shaft 21 of the servo motor 13 via a coupling mechanism 23. As shown in FIGS. 4 and 5, a hollow member 27 is accommodated and arranged in the housing 1. The hollow member 27 is inserted and fixed between the pair of end members 7 and 7 already described. The ball screw 25 is accommodated and arranged in the hollow member 27. The hollow member 27 is made of a nonmagnetic material. In this embodiment, it is made of stainless steel (SUS).
In addition, for example, it is conceivable to use an extruded aluminum material.

  A ball nut 29 is accommodated / arranged in the hollow member 27, and the ball nut 29 is screwed / arranged with the ball screw 25. The ball screw 25 is rotatably supported by bearing members 31, 33, and 37. A polymer lubricating member 35 is installed on the outer periphery of the ball screw 25. The polymer lubricating member 35 is a resin containing lubricating oil.

  As shown in FIGS. 4 and 5, a piston portion 41 is connected to the ball nut 29. The piston portion 41 includes a first sleeve 43 and a second sleeve 45, and the right end of the first sleeve 43 in FIG. 5 is screwed and coupled to the left end of the second sleeve 45 in FIG. 5. The right end of the second sleeve 45 in FIG. 5 is attached so as to cover the left end of the ball nut 29 in FIG. 5 and is connected and fixed by a plurality of fixing bolts 46.

Needle bearings 51 and 53 are attached to the left and right ends of the outer periphery of the first sleeve 43 of the piston portion 41. or,
Sliding bearing members 55 and 57 are installed between the outer peripheral sides of these needle bearings 51 and 53 and the hollow member 27. A drive side magnet portion 60 is provided between the needle bearings 51 and 53 on the outer peripheral side of the first sleeve 43. The drive-side magnet unit 60 has a configuration in which a plurality of drive-side magnets 61 and yokes 62 are alternately stacked and arranged. An inner magnet 63 for a magnetic rotational direction coupling mechanism is installed on the outer peripheral side of the second sleeve 45. A fixing nut 52 is screwed to the left side of the needle bearing 51 in FIG.

  A slider portion 71 is installed on the outer peripheral side of the hollow member 27. The slider portion 71 includes a cylindrical member 73 and end members 75 and 77 attached to both ends of the cylindrical member 73. Sliding bearing members 79 and 81 are installed on the inner peripheral side of the cylindrical member 73. These sliding bearing members 79 and 81 are installed at positions corresponding to the already described sliding bearing members 55 and 57 on the piston portion 41 side.

A driven-side magnet portion 82 is provided between the sliding bearing members 79 and 81. The driving-side magnet unit 60 and the driven-side magnet unit 82 described above constitute a magnetic thrust direction coupling mechanism 80. The driven magnet portion 82 has a configuration in which a plurality of driven magnets 83 and yokes 84 are alternately stacked and arranged. An outer magnet 85 for a magnetic rotational direction coupling mechanism is installed on the inner peripheral side of the end member 77. The driven magnet 83 and the outer magnet 85 for the magnetic rotational direction coupling mechanism both have a resin coating or mold on the surface thereof, thereby obtaining a rust prevention effect. .
Incidentally, since the drive-side magnet 61 and the inner magnet 63 for the magnetic rotary coupling mechanism are both housed and arranged on the inner peripheral side of the hollow member 27, the necessity for rust prevention is low.

Here, the relationship between the drive side magnet part 60 already demonstrated and the driven side magnet part 82 is demonstrated in detail. First, looking at the magnetic poles of the drive side magnet 61 that constitutes the drive side magnet unit 60 and the driven side magnet 83 that constitutes the driven side magnet unit 82, first, the drive side magnet 61 and the driven side magnets in the radial direction. The different polarities of the magnet 83 are opposed to each other and arranged so as to exert an attractive force. Further, when the adjacent drive-side magnets 61 and 61 are viewed along the axial direction, the same poles are opposed to each other. Similarly, when the adjacent driven magnets 83 and 83 are viewed along the axial direction, the same poles are opposed to each other. Then, when the piston portion 41 moves in the axial direction, the slider portion 71 follows and moves in the same direction by the action of the plurality of driving side magnets 61 and the plurality of driven side magnets 83.

  Next, the relationship between the already described inner magnet 63 for the magnetic rotational direction coupling mechanism and the outer magnet 85 for the magnetic rotational direction coupling mechanism will be described. The magnetic rotational direction coupling mechanism outer magnet 63 and the magnetic rotational direction coupling mechanism outer magnet 85 constitute a magnetic rotational direction coupling mechanism 86. The material of the inner magnet 63 for the magnetic rotational coupling mechanism and the outer magnet 85 for the magnetic rotational coupling mechanism may be, for example, a sintered magnet such as a neodymium magnet or a ferrite magnet, but is a brittle material. Therefore, there is a problem that machining is difficult and processing man-hours are required. Therefore, in this embodiment, the magnet is manufactured with a bonded magnet by compression molding. As a result, post-processing can be easily performed and various dimensions can be easily accommodated. Further, since the length can be adjusted within the range of the mold in the compression direction, the magnets having different lengths without using many molds, specifically, the inner magnet 63 for the magnetic rotational direction coupling mechanism, The outer magnet 85 for the magnetic rotational direction coupling mechanism can be easily manufactured. An optimum magnetic rotational direction coupling mechanism 86 corresponding to the motor torque and the lead can be easily manufactured.

  The form of magnetization of the inner magnet 63 for the magnetic rotational coupling mechanism and the outer magnet 85 for the magnetic rotational coupling mechanism is shown in FIG. First, “N pole” and “S pole” are alternately magnetized on the outer periphery of the inner magnet 63 for the magnetic rotational direction coupling mechanism. Similarly, “N pole” and “S pole” are alternately magnetized on the inner peripheral portion of the outer magnet 85 for the magnetic rotational direction coupling mechanism. Then, the “N pole” and “S pole” of each other are settled in a state of being adsorbed. The operation in the rotational direction of the ball nut 29 and the piston portion 41 is regulated by the magnetic rotational direction coupling mechanism 86 having such a configuration.

Specifically, for example, when an external force in the axial direction is applied to the slider portion 71 from the outside, even if the ball screw 25 is locked, the slider portion 71 and the magnetic force It is expected that the ball nut 29 will rotate through the piston part 41 coupled to the. When the ball nut 29 is rotated, the slider portion 71 is moved in the axial direction. In order to prevent such a phenomenon, the magnetic rotational direction coupling mechanism 86 is employed, and the rotation of the ball nut 29 is restricted, and the slider portion 71 moves carelessly by the action of an external force. It is what prevents it.

In this embodiment, bearings 51 and 53 are attached to the piston portion 41 so that the piston portion 41 can rotate. However, this reduces the sliding resistance in the rotation direction of the piston portion 41 and reduces the magnetic force. This is because the required torque of the rotary direction coupling mechanism 86 is suppressed and torque fluctuations and variations are suppressed.

Further, the magnetic rotational direction coupling mechanism outer magnet 85 constituting the magnetic rotational direction coupling mechanism 86 is longer in the axial direction than the magnetic rotational direction coupling mechanism inner magnet 63. Specifically, the difference in length between the two is set to be twice or more the amount of displacement until the magnetic thrust direction coupling mechanism 80 steps out. The reason is that if a force is applied to the slider portion 71 in the axial direction, the relative positional relationship between the slider portion 71 and the piston portion 41 will be proportional to the amount, and at the same time the inner side of the magnetic rotational coupling mechanism A difference also arises in the relative positional relationship in the axial direction between the magnet 63 and the outer magnet 85 for the magnetic rotational coupling mechanism. When the inner magnet 63 for the magnetic rotational direction coupling mechanism and the outer magnet 85 for the magnetic rotational direction coupling mechanism are displaced from the normal positions, the magnetic coupling force in the rotational direction is also weakened, and the magnetic rotational direction coupling mechanism 86 is It is expected that predetermined positioning cannot be performed due to the cause of step-out. In order to prevent this, the length of the outer magnet 85 for the magnetic rotational coupling mechanism is made longer than the length of the inner magnet 63 for the magnetic rotational coupling mechanism. This is set to at least twice the amount of displacement until the magnetic thrust direction coupling mechanism steps out.

Further, since the piston portion 41 and the slider portion 71 are fixed only by the attraction force of the magnetic thrust direction coupling mechanism 80 composed of the driving side magnet portion 60 and the driven side magnet portion 82, an excessive force is applied from the outside. When a large torque is output to the servo motor 11 with the slider 71 locked, the drive side that constitutes the magnetic thrust direction coupling mechanism 80 according to the generated thrust. The relative positional relationship between the magnet unit 60 and the driven-side magnet unit 82 is shifted, and eventually the step-out occurs. And once it has stepped out, it is necessary to forcefully apply force to return the positional relationship between the slider portion 71 and the piston portion 41 to the original state. However, in this state, it becomes very difficult to force a large force from the outside or to force the slider unit 71 from the outside in a locked state, or to perform disassembly or the like.

Therefore, the magnetic fastening force of each of the magnetic thrust direction coupling mechanism 80 and the magnetic rotational direction coupling mechanism 86 is adjusted in advance so as not to cause the above-described step-out phenomenon. Specifically, the torque of the magnetic rotational coupling mechanism 86 is adjusted so that the magnetic rotational direction coupling mechanism 86 steps out before the magnetic thrust direction coupling mechanism 80 steps out. It is. That is, the magnetic rotational direction coupling mechanism 86 is used as a torque limiter.
Even if the magnetic rotational direction coupling mechanism 86 is stepped out, it does not cause any inconvenience because it rotates only by a predetermined angle and moves to the next attraction point as shown in FIG. is there.

Further, another cylindrical member 90 is installed on the outer periphery of the cylindrical member 73 of the slider portion 71 with a gap. A floating pin 92 is attached between the cylindrical member 90 and the cylindrical member 73. Stop ring members 94 and 96 are attached between the cylindrical member 90 and the cylindrical member 73.

Further, the rotation of the cylinder portion 71 is restricted by the guide mechanism 91. That is, as shown in FIGS. 2 and 3, a pair of guide shafts 93, 93 are installed on both the left and right sides of the cylindrical member 90 of the slider portion 71, and both ends of the pair of guide shafts 93, 93 are ends. It is fixed to the members 7 and 7. Guide members 95, 95 are slidably attached to the pair of guide shafts 93, 93. The pair of guide members 95 and 95 are fixed to the cylindrical member 90 of the slider portion 71. The cylindrical member 90 is guided by the guide mechanism 91 in a state where its rotation is restricted. Further, since the cylindrical member 73 is paired with the cylindrical member 90 in the rotational direction by the floating pin 92, the rotation of the cylindrical member 73 is also restricted. The rotation is restricted. Further, since the rotation of the slider portion 71 is restricted, the rotation of the piston portion 41 and the ball nut 29 is restricted via the magnetic rotational direction coupling mechanism 86 already described.

In this case, any external force is applied to the cylindrical member 90. In this case, the floating pin 92 only moves in the radial direction, and the inner cylindrical member 73 side is affected. There is nothing. In other words, the cylinder portion 71 inside the cylindrical member 90 is held in a certain floating state so as not to be affected by an inadvertent external force on the outer peripheral side of the hollow member 27.

As shown in FIG. 1, a cover 101 is attached to the upper end opening of the housing 1, and gaps 103, 103 are formed between the cover 101 and the left and right side walls 5, 5 of the housing 1. ing. The gaps 103 and 103 serve as passages for the upper end protrusions 95a and 95a of the guide members 95 and 95.

The operation will be described based on the above configuration.
The ball screw 25 rotates in the same direction by rotating and driving the servo motor 11 in an appropriate direction. As the ball screw 25 rotates, the ball nut 29 and the piston portion 41 move in either direction. Then, by the movement of the piston portion 41, the slider portion 71 disposed on the outer peripheral side via the hollow member 27 causes the driving side magnet portion 60 and the driven side magnet portion 82 that constitute the magnetic thrust direction coupling mechanism 80. It moves in the same direction by the action of.
In this series of operations, the rotation of the slider portion 71 is restricted by the guide mechanism 91, and the rotation of the piston portion 41 and the ball nut 29 is restricted via the magnetic rotational direction coupling mechanism 86. It is what.
A case where some external force is applied to the slider portion 71 while the slider portion 71 is stopped will be described. In this case, since the rotation of the piston portion 41 and the ball nut 29 is restricted by the magnetic rotational direction coupling mechanism 86, the ball nut 29 can be prevented from rotating carelessly. Thereby, malfunction of the slider part 71 is prevented.
A case will be described in which a positional deviation occurs between the driving side magnet portion 60 and the driven side magnet portion 82 constituting the magnetic thrust direction coupling mechanism 80 due to the action of some external force. In this case, the magnetic rotation direction coupling mechanism outer magnet 85 constituting the magnetic rotation direction coupling mechanism 86 is configured to be longer in the axial direction than the magnetic rotation direction coupling mechanism inner magnet 63. In particular, the difference in length between the two is set to be twice or more the amount of displacement until the magnetic thrust direction coupling mechanism 80 steps out, so the magnetic rotational direction constituting the magnetic rotational direction coupling mechanism 86 is set. The coupling mechanism inner magnet 63 does not protrude from the magnetic rotational direction coupling mechanism outer magnet 85, and a constant torque can always be maintained in the rotational direction. Further, it is possible to prevent a situation in which the magnetic rotational direction coupling mechanism 86 is out of step and the predetermined positioning cannot be performed.
Further, it is assumed that a situation occurs in which some external force acts on the magnetic thrust direction coupling mechanism 80 to cause the step-out. In this case, the torque of the magnetic rotational direction coupling mechanism 86 is adjusted so that the magnetic rotational direction coupling mechanism 86 will step out before the magnetic thrust direction coupling mechanism 80 steps out. The step-out of the magnetic thrust direction coupling mechanism is reliably prevented. That is, the magnetic rotational direction coupling mechanism 86 is made to function as a torque limiter. Further, when the magnetic thrust direction coupling mechanism 80 has stepped out, it will be difficult to perform a subsequent reset. However, when the magnetic rotational direction coupling mechanism 86 has stepped out, the rotational direction is predetermined. It only rotates to an angle and moves to the next suction point, and no inconvenience occurs.

As described above, according to the present embodiment, the following effects can be obtained.
First, since all the mechanical components including the ball screw 25 and the ball nut 29 are housed and isolated in the hollow member 27, they can be used without any trouble even in the case of liquid droplets or direct jet flow. I can do it now.
In addition, since all the mechanical components including the ball screw 25 and the ball nut 29 are housed and isolated in the hollow member 27, it is possible to prevent internal oil and grease from flowing out to the outside. Thus, an actuator that can be used in a clean environment without polluting the external environment can be provided.
Further, since it is not necessary to employ an expensive bellows or a complicated labyrinth mechanism as in the prior art, the processing cost can be reduced, and a slider type actuator having a dustproof and dripproof structure can be easily realized at a low cost.
Further, since the magnetic rotational direction coupling mechanism 86 is provided, it is possible to prevent the ball nut 29 from rotating carelessly even if some external force is applied to the slider portion 71. Thus, the malfunction of the slider portion 71 can be prevented.
In the magnetic rotational direction coupling mechanism 86, the magnetic rotational direction coupling mechanism outer magnet 85 constituting the magnetic rotational direction coupling mechanism 86 is axially compared with the magnetic rotational direction coupling mechanism inner magnet 63. It has a long configuration. Specifically, the difference in length between the two is set to be twice or more the amount of displacement until the magnetic thrust direction coupling mechanism 80 steps out. As a result, even if a positional deviation occurs between the driving side magnet portion 60 and the driven side magnet portion 82 constituting the magnetic thrust direction coupling mechanism 80, the magnetic type constituting the magnetic rotational direction coupling mechanism 86. Since the rotation direction coupling mechanism inner magnet 63 does not protrude from the magnetic rotation direction coupling mechanism outer magnet 85, a constant torque can always be maintained in the rotation direction. Further, it is possible to prevent a situation in which the magnetic rotational direction coupling mechanism 86 is out of step and cannot be positioned in a predetermined manner.
Further, the torque of the magnetic rotational direction coupling mechanism 86 is adjusted so that the magnetic rotational direction coupling mechanism 86 is stepped out before the magnetic thrust direction coupling mechanism 80 is stepped out. The step-out of the thrust direction coupling mechanism 80 can be prevented, and the occurrence of problems due to the step-out of the magnetic thrust direction coupling mechanism 80 can be prevented.
Since both the driven magnet 83 and the outer magnet 85 for the magnetic rotational direction coupling mechanism are coated with resin or molded on the surfaces thereof, a desired rust prevention effect can be obtained.
Also, the magnetic rotational coupling mechanism inner magnet 63 and the magnetic rotational coupling mechanism outer magnet 85 constituting the magnetic rotational coupling mechanism 86 are both made of compression-bonded magnets. It can be easily post-processed and can easily cope with various dimensions. Further, since the length can be adjusted within the range of the mold in the compression direction, the inner magnet 63 for the magnetic rotational direction coupling mechanism having different lengths without using many molds, the magnetic rotational direction coupling mechanism The outer magnet 85 can be easily manufactured. Then, the optimum rotational coupling mechanism 86 corresponding to the motor torque and the lead can be easily manufactured.

Next, a second embodiment of the present invention will be described. In the second embodiment, in the configuration of the first embodiment, the maximum output torque of the servo motor 11 is limited by applying a current limit on the servo motor 11 side. It is.
Other configurations are the same as those in the first embodiment.
With such a configuration, the magnetic rotational direction coupling mechanism 86 functions as a torque limiter and the maximum output torque of the servo motor 11 is limited. Step-out can be reliably prevented.

Next, a third embodiment of the present invention will be described. In the case of the third embodiment, a pressure adjustment mechanism is provided so that a pressure difference does not occur in the hollow member 27 or the servo motor cover 9 due to a change in environmental temperature. Specifically, the end face of the hollow member 27 is provided with a sealing member that is air permeable but can maintain liquid tightness, thereby allowing the inside of the hollow member 27 to communicate with the outside air so that no pressure difference is generated. It is a thing. Similarly, the servo motor cover 9 is also configured such that a similar sealing member is interposed on the end face thereof so that the inside of the servo motor cover 9 communicates with the outside air so that no pressure difference is generated.
Other configurations are the same as those in the first embodiment.
And by setting it as such a structure, generation | occurrence | production of various malfunctions, for example, dew condensation etc., can be prevented when a pressure difference generate | occur | produces.

The present invention is not limited to the first to third embodiments.
First, the number, size, etc. of the drive unit side magnet and the driven unit side magnet constituting the drive side magnet unit and the driven side magnet unit are not particularly limited.
In the case of the first to third embodiments, the ball screw / ball nut mechanism has been described as an example, but in addition to this, a configuration using a trapezoidal screw as a feed screw, and various other configurations Is assumed.
Moreover, what was illustrated about the aspect of magnetization of the drive part side magnet and driven part side magnet which comprise a drive side magnet part and a driven side magnet part is an example to the last.

The present invention relates to an actuator, and in particular, to an actuator devised so that it can be used without problems even under a dusty environment or under a direct jet of water, for example, in a food processing factory or a packing factory. It is suitable for various actuators used.

It is a figure which shows the 1st-3rd embodiment of this invention, and is a perspective view which shows the external appearance of the whole actuator. It is a figure which shows the 1st-3rd embodiment of this invention, and is a perspective view which shows the structure inside an actuator. It is a figure which shows the 1st-3rd embodiment of this invention, and is a top view which shows the structure inside an actuator. It is a figure which shows the 1st-3rd embodiment of this invention, and is sectional drawing which shows the structure inside an actuator. It is a figure which shows the 1st-3rd embodiment of this invention, and is sectional drawing which expands and shows the V section of FIG. It is a figure which shows the 1st-3rd embodiment of this invention, and is a cross-sectional view which shows the structure of a magnetic rotation direction coupling mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Housing 3 Bottom wall 5 Side wall 7 End member 9 Servo motor housing 11 Servo motor 25 Ball screw (screw)
27 Hollow member 29 Ball nut (nut)
41 Piston part 60 Drive side magnet part 61 Drive side magnet 63 Inner magnet 71 for magnetic rotation direction coupling mechanism Slider part 80 Magnetic thrust direction coupling mechanism 82 Driven side magnet part 83 Driven side magnet 85 Magnetic rotation direction coupling Outer magnet 86 for mechanism Magnetic rotation direction coupling mechanism

Claims (7)

A hollow member;
A screw that is housed and disposed on the inner peripheral side of the hollow member and is driven to rotate;
A nut housed and arranged on the inner peripheral side of the hollow member and screwed and arranged with respect to the screw;
A piston portion housed and disposed on the inner peripheral side of the hollow member and fixed to the nut;
A driving side magnet portion provided in the piston portion;
A slider part arranged movably on the outer peripheral side of the hollow member in a state where its rotation is restricted;
A driven-side magnet unit that is provided in the slider unit and constitutes a magnetic thrust direction coupling mechanism in combination with the driving-side magnet unit;
Comprising
By rotating and driving the screw, the nut and the piston part are moved in an appropriate direction, whereby the action of the magnetic thrust direction coupling mechanism composed of the driving side magnet part and the driven side magnet part is achieved. The slider is configured to move the slider portion in the same direction. The actuator according to claim 1, wherein
The said hollow member is comprised from the nonmagnetic material, The actuator characterized by the above-mentioned. The actuator according to claim 1 or 2,
The actuator is characterized in that the driven-side magnet portion is a magnet whose surface is coated or molded with resin. The actuator according to claim 1, wherein
An actuator characterized in that a magnetic rotational direction coupling mechanism is provided between the piston portion and the slider portion with the hollow member interposed therebetween. The actuator according to claim 4, wherein
The magnetic rotation direction coupling mechanism includes an inner magnet for a magnetic rotation direction coupling mechanism provided in the piston portion, and an outer magnet for a magnetic rotation direction coupling mechanism provided in the slider portion. An actuator characterized by that. In the actuator according to any one of claims 1 to 5,
The actuator is characterized in that the screw is a ball screw. In the actuator according to any one of claims 1 to 5,
The actuator is characterized in that the screw is a trapezoidal screw.

Images