JP2018129932A - Linear actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology capable of making a stator and a front housing into a stable positional relation without increasing costs.SOLUTION: A linear actuator 100 is provided with: a stator yoke 115 having an end surface in an axial direction; a bobbin 113 arranged inside the stator yoke 115, and around which a coil 111 is wound; a front plate 120 fixed to the end surface of the stator yoke 115; and a front housing 150 coupled with the front plate 120, in which the bobbin 113 is provided with a boss part 14 inserted into a hole provided on the front plate 120, the front housing 150 is provided with a boss part 152 passing through the hole provided on the front plate 120, and the tip of the boss part 152 contacts the end surface of the stator yoke 115.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a linear actuator.

  A linear actuator having a structure for converting rotation of a rotor into linear motion of an output shaft is known (for example, see Patent Document 1). In the structure described in Patent Document 1, the stator, the front plate, and the front housing are stacked in the axial direction. In this structure, the technique described in Patent Document 2 is known. In this technique, when the stator is resin-molded, a boss portion that is coupled to the hole portion of the front plate is formed of the mold resin.

JP 2013-24360 A JP-A-8-98498

  In the technique described in Patent Document 2, the boss portion (projection portion) is formed by a resin that molds the stator. In this technique, the protruding length of the boss portion is determined by the conditions at the time of mold formation. However, the manufacturing conditions for forming the boss part by allowing the resin poured into the narrow part to protrude from the hole are delicate, and strict management of the manufacturing conditions is required to accurately control the protruding length of the boss part, resulting in high cost. It becomes.

  If the conditions of the process of molding the stator with resin are relaxed, it will be advantageous in terms of cost, but if so, the protruding length of the boss portion will not be stable. In this structure, the positional relationship between the stator and the front housing is determined by the protruding length of the boss portion. Therefore, if the protruding length of the boss portion varies, the positional relationship between the stator and the front housing varies. Since this variation is a variation in the movable range of the output shaft, it is necessary to suppress it as much as possible.

  In view of such a background, an object of the present invention is to provide a technique capable of providing a stable positional relationship between a stator and a front housing without causing an increase in cost.

  The present invention includes a stator yoke having an end face in the axial direction, a bobbin disposed inside the stator yoke and wound with a coil, a front plate fixed to the end face of the stator yoke, and the front plate. The front housing has a first protrusion that passes through a first hole provided in the front plate, and the bobbin has a second hole provided in the front plate. A linear actuator in which a second protrusion to be inserted is provided, and a tip of the first protrusion is in contact with the end face of the stator yoke.

  In the present invention, the front plate is positioned with respect to the stator yoke by the second protrusion, the front plate is made of metal and fixed to the stator yoke by welding, and the front plate is The structure provided with the arm part engaged with a front housing is preferable.

  In the present invention, it is preferable that the distance between the front housing and the end face of the stator yoke around the first protrusion is larger than the thickness of the front plate.

  Another invention disclosed in this specification includes a rotor connected to a shaft, a stator disposed around the rotor, a bearing that rotatably supports the rotor, a contact with the bearing, and the bearing. A bearing housing space for housing; a housing having a first protrusion that contacts the end surface of the stator; a base that contacts the end surface of the stator; and a support that supports the housing; A linear actuator having a plate formed and having a first hole through which the first protrusion passes.

  In this invention, the stator includes a bobbin wound with a coil and having a second protrusion, and a through hole formed on the end surface of the stator and through which the second protrusion passes, and the base of the plate For this, a configuration in which a second hole in which the second protrusion is disposed on the inside is formed is preferable.

  In the above invention, it is preferable that the thickness of the plate in the rotation axis direction of the rotor is shorter than the length of the first protrusion. In the above invention, a configuration in which a gap exists between the end surface of the second protrusion and the housing is preferable.

  According to the present invention, the stator and the front housing can be in a stable positional relationship without incurring an increase in cost.

It is a perspective view of the linear actuator of an embodiment. It is a disassembled perspective view of the linear actuator of embodiment. It is sectional drawing of the linear actuator of embodiment. It is a perspective view (A) and (B) of a bobbin in an embodiment. They are the perspective view (A) and the front view (B) which show the state which attached the front plate to the stator structure in embodiment. It is the perspective view (A) and front view (B) of the front housing of embodiment. It is the expanded sectional view which expanded a part of FIG.

(Constitution)
FIG. 1 shows a linear actuator 100 according to an embodiment. FIG. 2 shows an exploded perspective view of the linear actuator 100. FIG. 3 shows a sectional view of the linear actuator 100 (a sectional view taken along the axis).

  The linear actuator 100 is fixed to a stator yoke 115 having an end face 115a in the axial direction, a bobbin 113 (see FIG. 4) around which the coil 111 is wound, and an end face 115a of the stator yoke 115. The front plate 120 and the front housing 150 coupled to the front plate 120 are provided, and the bobbin 113 has a boss portion 14 inserted into a hole 121 (see FIGS. 2 and 5A) provided in the front plate 120. The front housing 150 is provided with a boss portion 152 (see FIG. 6) to be inserted into the hole 123 provided in the front plate 120, and the tip of the boss portion 152 comes into contact with the end surface 115a of the stator yoke 115. Has a structure.

  Hereinafter, the linear actuator 100 will be described in detail. As shown in FIG. 2, the linear actuator 100 includes a stator structure 110, a front plate 120, a rotor 130, a shaft 140, a front housing 150, and a tip portion 142.

  The stator structure 110 has a substantially cylindrical shape and has a stator structure of a claw pole type stepping motor. Stator structure 110 includes coils 111 and 112 (see FIG. 3), bobbins 113 and 114, stator yokes 115 and 117 made of a soft magnetic metal material such as an electromagnetic steel plate, and stator yokes 116 and 118, and an internal gap. The resin 119 (see FIGS. 3 and 5A) is filled and integrated. Here, the stator yokes 115 and 117 constitute a pair and constitute a stator yoke of the first claw pole type motor, and the stator yokes 116 and 118 constitute a pair and constitute a stator yoke of the second claw pole type motor. Generally, the stator yokes 115 and 116 are called outer yokes, and the stator yokes 117 and 118 are called inner yokes.

  The coil 111 forms a field coil and is wound around a resin bobbin 113 (see FIG. 4). The bobbin 113 around which the coil 111 is wound is housed inside the stator structure 110 (stator yoke 115). The bobbin 113 is manufactured by an injection molding method using a resin, and includes a cylindrical portion 11 (see FIG. 4), and flange portions 12 and 13 extending radially outward from both ends of the cylindrical portion 11 in the axial direction. ing.

  One flange portion 12 is provided with three boss portions 14 that are protruding portions protruding in the axial direction. The boss portions 14 are provided at positions at equal angular intervals (every 120 °). The boss portion 14 is formed as a part of the bobbin 113 simultaneously with the bobbin 113 by an injection molding method. A hole 15 for fixing the terminal pin 125 (see FIG. 3) is formed in the upper portion of the bobbin 113. A lead wire drawn from the coil 111 is connected to a terminal pin 125 (see FIG. 3) fixed to the hole 15.

  The stator yoke 115 has an outer cylindrical portion, an inner tooth portion, and a plate-shaped flat ring portion connecting the outer cylindrical portion and the inner tooth portion (the back surface of the flat ring portion is the end surface 115a of the stator yoke 115). . A bobbin 113 around which a coil 111 is wound is accommodated between the outer cylindrical portion and the inner tooth portion. The inner tooth portion of the stator yoke 115 has a plurality of first teeth 115b (see FIGS. 3 and 5A) extending in the axial direction (direction of the end housing 170).

  The stator yoke 117 is a member paired with the stator yoke 115, and includes a plate-shaped flat ring portion and a plurality of second teeth 117b extending in the axial direction from the inner edge of the flat plate ring portion (see FIG. 5A). : Not shown in FIG. 3). As shown in FIG. 5 (A), the plurality of first teeth 115b and the plurality of second teeth 117b extend in opposite directions to each other and are in mesh with each other with a gap therebetween. Has been. This is the same as in the case of a normal claw pole type motor. A gap between the first teeth 115b and the second teeth 117b is filled with a resin 119 filled in the stator structure 110.

  The bobbin 114 is also made of resin, and the coil 112 is wound around it. As with the stator yoke 115 side, the stator yokes 116 and 118 have a positional relationship structure in which a plurality of teeth are engaged with each other in a state of having gaps alternately. A space between the teeth of the stator yoke 116 and the teeth of the stator yoke 118 is filled with a resin 119 filled in the stator structure 110.

  The end face 115a of the stator yoke 115 is provided with three holes 115c (see FIG. 3) through which the boss part 14 of the bobbin 113 is inserted, and the boss part 14 is inserted into the three holes 115c. The tip of the boss portion 14 inserted into the hole 115c protrudes from the hole 115c to the front housing 150 side.

  5A and 5B show a state in which the front plate 120 is attached to the stator yoke 115 (stator structure 110). The front plate 120 is made of metal and is fixed to the stator yoke 115 by welding.

  The front plate 120 has a flat annular shape and includes a base portion that contacts the end surface 115a of the stator yoke 115. The base portion has three holes 121 into which the three boss portions 14 projecting from the stator yoke 115 in the axial direction are fitted. Is provided. The front plate 120 is positioned with respect to the stator yoke 115 by fitting the three boss portions 14 into the three holes 121.

  The front plate 120 is provided with fixing arm portions 122 having openings 122a at three ends. The fixing arm portion 122 is a member that couples the front plate 120 and the front housing 150, and functions as a support portion that supports the front housing 150 on the front plate 120. As shown in FIG. 1, the front plate 120 is coupled to the front housing 150 by deforming the fixing arm portion 122 and engaging the opening 122 a (see FIG. 2) with the protrusion 151 of the front housing 150.

  FIG. 6 shows a perspective view (A) and a front view (B) of the front housing 150. The front housing 150 is made of resin and is formed by an injection molding method. The front housing 150 is provided with three boss portions 152 that are protruding portions protruding in the axial direction. The boss portion 152 is manufactured by an injection molding method using resin, and the boss portion 152 is simultaneously formed as a part of the front housing 152 at the time of manufacturing.

  The boss 152 is inserted into the hole 123 provided in the front plate 120 and passes through the inside of the hole 123. The bottom portion of the hole 123 exposes the end surface 115a in the axial direction of the stator yoke 115 (see FIG. 5A), and the tip of the boss portion 152 contacts the end surface 115a in the axial direction of the stator yoke 115. With this structure, the relative positional relationship in the axial direction between the front housing 150 and the stator structure 110 is determined. The protruding length of the boss portion 14 provided on the bobbin 113 is set to a dimension such that the tip thereof does not contact the front housing 150. In this example, the protruding length of the boss portion 14 from the end surface of the bobbin 113 is set to a dimension that does not protrude from the hole 121.

  As shown in FIGS. 2 and 3, the rotor 130 is held inside the stator structure 110 in a rotatable state. The rotor 130 includes an inner cylindrical member 131 and a cylindrical rotor magnet 132 fixed to the outer side of the inner cylindrical member 131. The rotor magnet 132 is a permanent magnet that is alternately magnetized with NSNS... Along the circumferential direction.

  A cylindrical female screw 133 having a female screw structure formed on the inner periphery is fixed to the axial center portion of the rotor 130 (inside the inner cylindrical member). The internal thread 133 meshes with an external thread structure 141 formed on the outer periphery of an elongated cylindrical shaft 140.

  The inner cylindrical member 131 constituting the rotor 130 is held in a freely rotatable state by ball bearings 134 and 135. More specifically, the outer ring of the ball bearing 134 is fixed to an end housing 170 fixed to the stator yoke 116, and the inner ring of the ball bearing 134 is fixed to an inner cylindrical member 131 constituting the rotor 130 ( The outer ring of the ball bearing 134 is in contact with the end housing 170 but not the rotor 130). The outer ring of the ball bearing 135 is fixed to the front housing 150, and the inner ring of the ball bearing 135 is fixed to the inner cylindrical member 131 constituting the rotor 130 (the outer ring of the ball bearing 135 is in contact with the front housing 150. But not in contact with the rotor 130). That is, the rotor 130 is held in a freely rotatable state by the ball bearings 134 and 135 in the end housing 170 and the front housing 150.

  A shaft 140 serving as an output shaft has a tip 142 fixed to the tip by a pin 144. A rotation preventing member 143 is fixed to the shaft 140. The front housing 150 is provided with a columnar space 153 that is a columnar space in which the shaft 140 and the rotation preventing member 143 are accommodated. The columnar space 153 has a shape of a cross section perpendicular to the axial direction, which is composed of an upper curved surface, a lower curved surface, and two planes that connect the upper curved surface and the lower curved surface. The cross-sectional shape is set.

  By making the cross-section of the columnar space 153 into the above-mentioned shape and the shape of the anti-rotation member 143 corresponding thereto, the anti-rotation member 143 can be slid in the axial direction without being able to rotate inside the columnar space 153. Yes. A cylindrical portion 156 constituting a part of the columnar space 153 extends from the front housing 150, and an inner flange portion 154 is formed at the tip of the cylindrical portion 156. And the shaft 140 which is an output shaft protrudes outside from the center of the inner side flange part 154. FIG. One end side (left side in FIG. 3) of the columnar space 153 is defined by an inner flange portion 154, and the other end side (right side in FIG. 3) is defined by a bearing housing space 135a in which the ball bearing 135 is housed. A groove 155 formed in the front housing 150 is formed in the bearing housing space 135a. The groove 155 is formed in the front housing 150 so that the end surface (the left side in FIG. 3) of the inner ring of the ball bearing 135 does not contact the front housing 150. The operating range of the distal end portion 142 in the outer direction (left direction in FIG. 3) is determined by the rotation preventing member 143 coming into contact with the inner flange portion 154 of the columnar space 153, and the movable range in the inner direction (right direction in FIG. 3). Is determined by the front end portion 142 hitting the inner flange portion 154 of the columnar space 153.

(Operation)
When an electric current is passed through the coils 111 and 112, the circumferential direction between the teeth of the stator yoke 115 and the stator yoke 117, that is, between the plurality of first teeth 115b and the plurality of second teeth 117b in FIG. A magnetic field having a component is generated. Similarly, a magnetic field having a circumferential component is generated between the teeth of the stator yoke 116 and the stator yoke 118. When the polarity of the driving current is switched at a specific timing, the direction of the magnetic field is periodically switched, and a driving force for rotating the rotor magnet 132 is generated.

  The rotor 130 and the female screw 133 are rotated together by the above driving force. Here, since the shaft 140 cannot be rotated by the anti-rotation member 143 and is movable in the axial direction, the shaft 140 having the male screw structure 141 meshed with the female screw 133 is rotated by the rotation of the female screw 133. Advance and retreat in the direction. The moving direction of the shaft 140 is determined by the rotating direction of the rotor 130. As the shaft 140 moves in the axial direction, the distal end portion 142 moves in the axial direction.

(Superiority)
FIG. 7A shows an enlarged view in which the boss portion 152 is enlarged. FIG. 7B shows an enlarged view in which the boss portion 14 is enlarged. The boss portion 14 is a part of the bobbin 113 manufactured by an injection molding method, and the protruding length can be accurately managed without cost. The boss 152 is also a part of the front housing 150 manufactured by the injection molding method, and the protruding length can be managed with high accuracy without cost.

  As shown in FIG. 7A, the boss portion 152 of the front housing 150 is in contact with the end surface 115 a of the stator yoke 115 through the hole 123 of the front plate 120. On the other hand, as shown in FIG. 7B, the boss portion 14 of the bobbin 113 is inserted into the hole 121 of the front plate 120 but is not in contact with the front housing 150.

  In the structure of the present embodiment, the positional relationship between the stator structure 110 and the front housing 150 is determined by the boss portion 152 coming into contact with the stator yoke 115. Here, since the boss portion 14 does not contact the front housing 150, the positional relationship between the stator structure 110 and the front housing 150 is determined by the protruding length of the boss portion 152. As described above, the protruding lengths of the boss portion 14 and the boss portion 152 can be managed with high accuracy without causing an increase in cost. Therefore, in the structure of the present embodiment, the positional relationship between the stator structure 110 and the front housing 150 can be accurately managed without causing an increase in cost.

  Further, by adjusting the projecting dimension of the boss portion 152, a distance T (clearance into which the front plate 120 enters) between the front housing 150 and the end surface 115 a of the stator yoke 115 around the boss portion 152 is set to be equal to that of the front plate 120. A value larger than the thickness t is set. The front plate 120 is fixed to the end surface 115a of the stator yoke 115 by resistance welding. Here, due to incomplete flatness between the front plate 120 and the end surface 115a of the stator yoke 115, uncertainty occurs in the path through which the welding current flows, and the front plate 120 slightly moves from the end surface 115a of the stator yoke 115. It may be in a floating state.

  Although there is variation in the floating state, the protrusion length (height) of the boss portion 152 is adjusted, and the clearance is ensured to ensure that the clearance from the end surface 115a of the stator yoke 115 of the front plate 120 caused by welding. Is allowed to float, and the occurrence of defects due to the float is suppressed.

  7A, the front housing 150 is in contact with the stator yoke 115 at the boss portion 152, and is in contact with the end surface (the left side in FIG. 3) of the outer ring of the ball bearing 135 at other portions. Since the protruding length of the boss portion 152 can be formed with high accuracy, the axial force applied to the ball bearing 135 from the front housing 150 and further from the ball bearing 135 to the rotor 130 via the contact portion described above is Variations between lots) can be suppressed. As a result, it is possible to suppress variation in the movable range of the output shaft (shaft 140) from product to product (between product lots).

(Other)
The number of the boss portions 14 and the boss portions 152 and the number of holes corresponding to these boss portions are not limited to three, and may be four or more. Further, the number of the boss portions 14 and the boss portions 152 may not be the same.

  DESCRIPTION OF SYMBOLS 11 ... Cylindrical part, 12 ... Flange part, 13 ... Flange part, 14 ... Boss part, 15 ... Hole, 100 ... Linear actuator, 110 ... Stator structure, 111 ... Coil, 112 ... Coil, 113 ... Bobbin, 114 ... Bobbin 115 ... Stator yoke, 115a ... End face, 115b ... Stator yoke 115 teeth, 116 ... Stator yoke, 117 ... Stator yoke, 117b ... Stator yoke 117 teeth, 118 ... Stator yoke, 119 ... Filled resin, 120 ... Front plate, 121 ... hole, 122 ... fixing arm, 123 ... hole, 125 ... terminal pin, 130 ... rotor, 131 ... inner cylindrical member, 132 ... rotor magnet, 133 ... female screw, 134 ... ball bearing, 135 ... ball Bearing, 135a ... Bearing housing space, 140 ... Shaft, 141 ... Male screw structure, 142 DESCRIPTION OF SYMBOLS ... Tip part, 143 ... Anti-rotation member, 144 ... Pin, 150 ... Front housing, 151 ... Protrusion, 152 ... Boss part, 153 ... Columnar space, 154 ... Inner housing part, 155 ... Groove, 170 ... End housing.

Claims (7)

A stator yoke having an end face in the axial direction;
A bobbin disposed inside the stator yoke and wound with a coil;
A front plate fixed to the end face of the stator yoke;
A front housing coupled to the front plate,
The front housing is provided with a first protrusion that passes through a first hole provided in the front plate,
The bobbin is provided with a second protrusion that is inserted into a second hole provided in the front plate,
A linear actuator in which a tip of the first protrusion is in contact with the end face of the stator yoke. The front plate is positioned with respect to the stator yoke by the second protrusion,
The front plate is made of metal and fixed to the stator yoke by welding,
The front plate is a linear actuator provided with an arm portion that engages with the front housing.   The linear actuator according to claim 2, wherein a distance between the front housing and the end surface of the stator yoke around the first protrusion is larger than a thickness of the front plate. A rotor connected to the shaft;
A stator disposed around the rotor;
A bearing that rotatably supports the rotor;
A housing having a bearing housing space that contacts the bearing and accommodates the bearing, and a first protrusion that contacts the end surface of the stator;
The linear actuator which has a base part which contacts the end surface of the said stator, and a support part which supports the said housing, and has a 1st hole which is formed in the said base part and the said 1st protrusion passes. The stator includes a bobbin wound with a coil and having a second protrusion, and a through-hole formed on the end surface of the stator through which the second protrusion passes.
The linear actuator according to claim 4, wherein a second hole in which the second protrusion is disposed inside is formed in the base portion of the plate.   The linear actuator according to claim 4, wherein a thickness of the plate in a rotation axis direction of the rotor is shorter than a length of the first protrusion.   The linear actuator according to claim 5 or 6, wherein a gap exists between an end surface of the second protrusion and the housing.

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