CN211239594U

CN211239594U - Electric motor

Info

Publication number: CN211239594U
Application number: CN202020114576.1U
Authority: CN
Inventors: 保科顕一
Original assignee: Nidec Sankyo Corp
Current assignee: Nidec Instruments Corp
Priority date: 2019-01-21
Filing date: 2020-01-17
Publication date: 2020-08-11
Anticipated expiration: 2030-01-17
Also published as: JP2020118179A

Abstract

The utility model provides a motor, it prevents to install rocking of rotating epaxial gear part, and can dispose rotation axis and gear part with one heart. The motor is characterized in that the motor comprises a rotating shaft and a gear component mounted on the rotating shaft, a shaft body side large diameter portion is arranged on one part of the rotating shaft in the circumferential direction, the shaft body side large diameter portion is a pair of curved surfaces with equal diameters and a maximum diameter, when one side in the axial direction of the rotating shaft is set to be an upper side and the other side is set to be a lower side, the shaft body side large diameter portion is formed in a mode that the diameter is gradually reduced from the lower side to the upper side of the rotating shaft, a point-symmetric position is formed in the shaft hole of the gear component when the shaft hole is observed in the depth direction, an abutting portion with an inner surface protruding inwards and an avoidance groove with an inner surface sunken are formed, one end of an arc of each shaft body side large diameter portion of the rotating shaft inserted into the shaft hole is.

Description

Electric motor

Technical Field

The utility model relates to a motor especially relates to gear parts's location technique.

Background

Patent document 1 discloses a motor device 1 in which a gear 20 is attached to an output shaft 12.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2018-33300

SUMMERY OF THE UTILITY MODEL

Technical problem to be solved by the utility model

The wobbling of the gear part attached to the rotating shaft causes noise and output error during driving of the motor. When the rotating shaft is press-fitted into the shaft hole of the gear component to prevent rattling and the gear component is brought into close contact with the rotating shaft, if the positions at which the shaft hole and the rotating shaft are in contact with each other are deviated from each other, the axes of these components are displaced and vibrations are generated.

In view of the above, an object of the present invention is to provide a motor capable of preventing a gear component attached to a rotating shaft from wobbling and concentrically disposing the rotating shaft and the gear component.

Technical solution for solving technical problem

In order to solve the above-mentioned technical problem, the utility model provides a motor, its main essence lies in, possesses: a gear component; and a rotation shaft having a shaft portion into which the gear member is fitted, wherein a shaft-side large diameter portion is provided in a part of the shaft portion in a circumferential direction, the shaft-side large diameter portion being a pair of curved surfaces having the same diameter and having the maximum diameter, wherein the shaft-side large diameter portion is formed such that the diameter thereof gradually decreases from below to above of the shaft portion when one side of the shaft portion in an axial direction is set to be upper and the other side is set to be lower, wherein an abutting portion having an inwardly protruding inner surface and an escape groove having a recessed inner surface are formed in a position of the shaft hole of the gear member, the position being point-symmetric when the shaft hole is viewed in a depth direction, and wherein one end of an arc of each of the shaft-side large diameter portions of the shaft portion inserted into the shaft hole is in contact with the abutting portion and the other end is evacuated into the escape.

The shaft hole of the gear member is provided with an abutting portion whose inner surface protrudes inward, and one end of the arc of the shaft-body-side large diameter portion of the shaft portion is intentionally brought into contact with the abutting portion, whereby the shaft portion and the gear member are reliably brought into contact, and the position at which they are brought into contact can also be controlled. Further, the gear member can be supported in a balanced manner without being biased to one side by providing the abutting portions at positions that are point-symmetric when the shaft hole is viewed in the depth direction of the shaft hole, and bringing one end of the arc of the large-diameter portion on the shaft body side into contact with each of the abutting portions.

In addition, the shaft body side large diameter portion of the present invention is formed such that the diameter gradually decreases from the lower side of the shaft portion toward the upper side. The shaft-side large-diameter portion is a pair of curved surfaces having the largest diameter in the circumferential surface of the shaft portion. Therefore, when one end of the circular arc of the shaft body side large diameter portion comes into contact with the abutting portion and the shaft body side large diameter portion moves in a direction away from the abutting portion (or the gear member rotates in a direction away from one end of the shaft body side large diameter portion), next, the other end of the circular arc comes into contact with the inner surface of the shaft hole. Therefore, for example, when the gear member is attached to the shaft portion, the gear member is inclined upward and downward, and both ends of the arc of the large diameter portion on one shaft side are caught in the shaft hole before both ends of the large diameter portion on the other shaft side, and thus the gear member may be fixed in an upward and downward inclined state. Therefore, by separately providing the escape grooves that recess the inner surface of the shaft hole at positions that are point-symmetric in the shaft hole, the other ends of the arcs of the large-diameter portions on the shaft body side are allowed to escape into the escape grooves without contacting the inner surface of the shaft hole, and this type of assembly failure can be reduced.

In the motor of the present invention, it is preferable that a portion of the circumferential surface of the shaft portion other than the shaft-side large diameter portion is a flat surface. Since it is easy to machine or form a part of the circumferential surface of the rotating shaft into a flat surface, the diameter of the shaft portion can be reduced with high accuracy in a portion other than the shaft-body-side large diameter portion. In this case, it is preferable that the outer shape of the shaft portion is a shape obtained by cutting out a flat surface on the other peripheral surface of a round substantially truncated cone-shaped shaft body, leaving a portion corresponding to the large diameter portion on the shaft body side.

Preferably, the shaft hole side large diameter portion, which is a portion of the inner surface of the shaft hole facing the shaft body side large diameter portion, is formed such that the diameter of the hole is gradually reduced from below the shaft hole to above. In this case, in the motor of the present invention, it is preferable that the shaft hole is a through hole, and when a portion between an upper end and a lower end of the shaft-side large diameter portion is an intermediate portion of the shaft-side large diameter portion, a diameter of the upper end of the shaft-hole-side large diameter portion is larger than a diameter of the upper end of the shaft-side large diameter portion and equal to a diameter of a certain portion of the intermediate portion, and a variation amount of the diameter per unit length in a vertical direction of the shaft-side large diameter portion is smaller than a variation amount of the diameter per unit length in a vertical direction of the shaft-hole-side large diameter portion.

The gear member is fixed to the upper end of the shaft hole of the gear member, instead of being fixed to the shaft portion by the lower end of the shaft hole of the gear member being caught, whereby the rattling of the gear member can be suppressed more reliably.

In the motor of the present invention, it is preferable that the rotation shaft is an output shaft of a built-in drive source, and a bearing portion surrounding a tip of the output shaft and having a clearance with the tip is further provided. At this time, it is preferable that a clearance between an outer surface of the output shaft and an inner surface of the bearing portion is larger than a clearance between the output shaft and another bearing portion supporting the output shaft.

Generally, the output shaft of the electric motor is not supported at its distal end by a bearing so as not to hinder the rotation of the output shaft. Therefore, when a large force is applied to the output shaft in the radial direction, the output shaft may be tilted and its rotation may be hindered. Therefore, by providing the bearing portion so as to surround the distal end of the rotation shaft of the penetration gear member, the influence of the output shaft when a large lateral pressure is applied can be reduced without hindering the normal rotation of the output shaft.

(effects of utility model)

Thus, according to the present invention, the motor can prevent the gear part mounted on the rotation shaft from shaking, and the rotation shaft and the gear part can be concentrically arranged.

Drawings

Fig. 1 is a perspective view of a geared motor according to an embodiment.

Fig. 2 is a side sectional view showing an internal structure of the stepping motor.

Fig. 3 is a perspective plan view showing a reduction gear mechanism of the geared motor.

Fig. 4 is a side sectional view showing an internal structure of the eighth gear (overload protection mechanism).

Fig. 5 is a plan view (a) of an output gear of the stepping motor and a plan view (b) of an output shaft.

Fig. 6 is a side sectional view (a) of an output gear of the stepping motor, and a side view (b) of the output shaft.

Fig. 7 is a plan view (a) and a side sectional view (b) showing a state in which an output gear is attached to an output shaft of a stepping motor.

Description of the reference numerals

G … geared motor; 90 … a housing; 901 … bearing section; 91 … output shaft; a 911 … gear portion; 912 … front end; 1 … stepping motor; 11 … motor housing; 12 … a cover plate; 121 … flanging part; 122 … bearings; 13 … gear plate; 131 … bearing; a 20 … stator; 30 … rotor; 31a … pinion gear; 41-47 … first gear-seventh gear; 48 … eighth gear; 48a … large diameter gear portion; 48b … small-diameter gear portion; a 50 … output shaft; 51 … a shaft portion; 52 … axle-body-side large-diameter portion; 521 … one end of the arc of the shaft-side large-diameter portion; 522 … the other end of the arc of the shaft-body-side large-diameter portion; 53 … flat portion; 55: an expanding portion; 59 … large diameter gear portion; 60 … output gear; 61 … tooth; 62 … axle hole; 63 … abutment; 64 … escape the slot; 65 … axle hole side large diameter part

Detailed Description

[ summary of the constitution ]

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The gear motor G described below is a motor that decelerates and outputs the rotation of the stepping motor 1 as a drive source.

Fig. 1 is a perspective view of the geared motor G. In the following description, "upper" and "lower" refer to directions parallel to the Z axis indicated by coordinate axes drawn in fig. 1 and the like, and the Z1 side is referred to as "upper" and the Z2 side is referred to as "lower". "front" and "rear" refer to directions parallel to the X axis indicated by the coordinate axes, and the X1 side is referred to as "front" and the X2 side is referred to as "rear". Similarly, "left and right" refers to a direction parallel to the Y axis displayed on the same coordinate axis.

In the geared motor G of the present embodiment, the connector housing 152 of the stepping motor 1 is exposed from an opening provided in the front surface of the housing 90, and the front end portion 912 of the output shaft 91 protrudes from an opening provided in the upper surface of the housing 90. A plurality of reduction gears are disposed between the stepping motor 1 and the output shaft 91, and the output torque of the stepping motor 1 is amplified by the reduction gears and transmitted to the output shaft 91. In fig. 1, a support shaft, a bearing, and the like for supporting the respective components in the housing 90 are not shown.

[ stepping Motor ]

Fig. 2 is a side sectional view showing the internal structure of the stepping motor 1. The stepping motor 1 can perform rotation angle control of a predetermined number of steps, and does not need to perform feedback control by a rotary encoder or the like separately. This reduces the number of parts and the size of the geared motor G as a whole.

The power supply terminal 29 of the stepping motor 1 is a pin terminal formed by bending both ends in the longitudinal direction thereof upward and downward. The downward bent portion of the power supply terminal 29 is disposed in the connector housing 152, and constitutes an external connection unit 292 to which a terminal of a male connector, not shown, is connected. The upwardly bent portion of the power supply terminal 29 constitutes a bundling portion 291 that bundles coil wires of the

stator coils

22, 27 of the stepping motor 1.

The stepping motor 1 of the present embodiment is a two-phase stepping motor, and the stator 20 thereof has an a-phase stator coil 22 wound on an a-phase bobbin 21 and a B-phase stator coil 27 wound on a B-phase bobbin 26. A terminal holding portion 21a, which is a thick portion holding the power supply terminal 29, is formed at the front edge of the a-phase bobbin 21. The a-phase stator coil 22 has claw-pole salient poles, i.e., an upper yoke 23a and a lower yoke 23 b. The B-phase stator coil 27 similarly has an upper yoke 28a and a lower yoke 28B. The lower yoke 28B of the B-phase stator coil 27 is formed by cutting a part of the bottom surface of the motor case 11 into the motor case 11.

The rotor 30 is disposed in the ring of the stator coils 22 and 27 with a predetermined air gap therebetween. The rotor 30 is composed of a rotor magnet 32 that is a permanent magnet, and a rotor holder 31 that is a resin shaft body insert-molded to the rotor magnet 32. A shaft hole penetrating vertically is formed at the radial center of the rotor holder 31, and a rotor support shaft 39 serving as a fixed shaft is inserted into the shaft hole. The rotor support shaft 39 is fixed to the bottom surface of the motor case 11 and the cover plate 12. The lower surface of the rotor 30 is supported by a plate spring 35, which is a leaf spring, and the rotor 30 is biased upward by the plate spring 35.

A gear plate 13 as a flat plate member is disposed on the upper surface of the stator 20. A pinion gear 31a as a gear portion is formed at an upper end of the rotor holder 31, and the pinion gear 31a protrudes upward from a through hole provided in the gear plate 13. A plurality of support shafts 49 are fixed to the upper surface of the stator 20 and the cover plate 12, and a first gear 41, a second gear 42, and a third gear 43, which will be described later, are rotatably supported by the support shafts 49. The output shaft 50 has a large diameter gear portion 59, which is a gear portion for meshing with the third gear 43, and the base end portion 58 of the output shaft 50 is rotatably supported by a bearing 131 formed on the gear plate 13.

The shaft portion 51, which is the tip end portion of the output shaft 50, protrudes upward from the flange 121 provided on the cover plate 12. The burring 121 is a flange-shaped portion that rises upward from an edge of the through-hole formed in the cover plate 12. An output gear 60, which is a gear member having a smaller diameter than the large diameter gear portion 59, is attached to the shaft portion 51. Further, an enlarged diameter portion 55 having a larger diameter than the shaft portion 51 is provided in the middle of the output shaft 50 in the axial direction. The position of the diameter-enlarged portion 55 corresponds to the position of the burring 121, and the diameter-enlarged portion 55 is rotatably supported by the burring 121 via a bearing 122. The large diameter gear portion 59 of the output shaft 50 and the output gear 60 attached to the shaft portion 51 constitute a fourth gear 44 which will be described later.

Further, the tip of the shaft 51 is surrounded by a bearing 901 provided on the inner surface of the housing 90. A gap is intentionally provided between the outer surface of the shaft portion 51 and the inner surface of the bearing portion 901. This clearance is a clearance to the extent that the shaft portion 51 and the bearing portion 901 do not contact each other during normal operation of the geared motor G, and is set larger than a clearance between the enlarged diameter portion 55 of the output shaft 50 and the bearing 122 or a clearance between the base end portion 58 of the output shaft 50 and the bearing 131.

Generally, the output shaft of the electric motor is not supported at its distal end by a bearing so as not to hinder the rotation of the output shaft. Therefore, when a large force is applied to the output shaft in the radial direction, the output shaft may be tilted and its rotation may be hindered. Therefore, in the geared motor G of the present embodiment, the bearing 901 surrounding the tip end of the shaft portion 51 with a predetermined gap is provided, so that the influence of the large lateral pressure applied to the output shaft 50 is reduced, and the normal rotation of the output shaft 50 is not hindered.

[ reduction gear mechanism ]

Fig. 3 is a perspective plan view showing a reduction gear mechanism of the geared motor G. The reduction gear mechanism of the geared motor G will be described below with reference to fig. 3.

The stepping motor 1 of the present embodiment includes a first gear 41, a second gear 42, and a third gear 43 that reduce the rotation speed of the rotor 30 and transmit the rotation speed to the output shaft 50. These gears are each a composite gear in which spur gears having different pitch circle diameters are integrated in the axial direction.

The rotation of the pinion 31a is decelerated by the first gear 41, the second gear 42, and the third gear 43, and transmitted to the output shaft 50. Specifically, the pinion 31a meshes with the large diameter gear portion 41a of the first gear 41, and the small diameter gear portion 41b of the first gear 41 meshes with the large diameter gear portion 42a of the second gear 42. Similarly, the small-diameter gear portion 42b of the second gear 42 meshes with the large-diameter gear portion 43a of the third gear 43. The small-diameter gear portion 43b of the third gear 43 meshes with the large-diameter gear portion 59 of the output shaft 50. The large diameter gear portion 59 of the output shaft 50 and the output gear 60 attached to the shaft portion 51 constitute the fourth gear 44, and the fourth gear 44 constitutes a reduction gear train of the geared motor G.

A fifth gear 45, a sixth gear 46, a seventh gear 47, and an eighth gear 48 are disposed between the output gear 60 of the stepping motor 1 and the output shaft 91 of the geared motor G. The gears of the fifth gear 45 to the seventh gear 47 are reduction gears, and are each a composite gear in which spur gears having different pitch circle diameters are integrated in the axial direction. The eighth gear 48 is a gear member provided with an overload protection mechanism that integrally rotates spur gears having different pitch diameters by frictional resistance.

The rotation of the output gear 60 is decelerated by the fifth gear 45, the sixth gear 46, and the seventh gear 47, and then accelerated by the eighth gear 48 and transmitted to the output shaft 91. Specifically, the output gear 60 meshes with the large diameter gear portion 45a of the fifth gear 45, and the small diameter gear portion 45b of the fifth gear 45 meshes with the large diameter gear portion 46a of the sixth gear 46. Similarly, the small-diameter gear portion 46b of the sixth gear 46 meshes with the large-diameter gear portion 47a of the seventh gear 47, and the small-diameter gear portion 47b of the seventh gear 47 meshes with the small-diameter gear portion 48b of the eighth gear 48. Thereby, the rotation of the output gear 60 is decelerated and transmitted to the eighth gear 48. The large diameter gear portion 48a of the eighth gear 48 meshes with the gear portion 911 of the output shaft 91. Thereby, the rotation of the seventh gear 47 is accelerated by the eighth gear 48 and transmitted to the output shaft 91. However, the gear train of the fifth gear 45 to the eighth gear 48 reduces the rotation of the output gear 60 as a whole and transmits the reduced rotation to the output shaft 91.

[ overload protection mechanism ]

Fig. 4 is a side sectional view showing an internal structure of the eighth gear 48. The eighth gear 48 of the present embodiment is an overload protection mechanism that integrally rotates the large diameter gear portion 48a and the small diameter gear portion 48b by frictional resistance, and idles the large diameter gear portion 48a to block a load when the load exceeding a predetermined threshold value is applied to the large diameter gear portion 48 a.

The eighth gear 48 includes a shaft core 71 as a rotation shaft, a large diameter gear portion 48a, first and second

annular plates

72 and 73 arranged to sandwich the upper and lower surfaces of the large diameter gear portion 48a, and a small diameter gear portion 48 b.

The shaft core portion 71 is a substantially cylindrical rotating shaft. The axial core portion 71 is provided with a diameter-enlarged portion 71b at an intermediate portion in the axial line L direction, and the diameter dimension of the diameter-enlarged portion 71b is locally formed large. The upper end portion 71e of the shaft core portion 71 and its vicinity are formed so as to gradually narrow in a step shape.

A connecting portion 71a to which the small-diameter gear portion 48b is attached is provided near the lower end of the shaft core portion 71. The connecting portion 71a is cut flat at a circumferentially symmetrical position, and the shaft hole of the small-diameter gear portion 48b is formed in the same shape. A spindle portion 71c to which the large diameter gear portion 48a is attached is provided between the enlarged diameter portion 71b and the upper end portion 71e of the spindle portion 71. The axle portion 71c is also cut in a planar shape at a circumferentially symmetrical position, similar to the connecting portion 71 a.

The lower surface 74 and the upper surface 75 of the large-diameter gear portion 48a are formed so that the inner portions thereof are lower than the teeth and the vicinity thereof by one step, and the lower portions thereof are formed with annularly extending

projections

74a, 75 a.

The first annular plate 72 and the second annular plate 73 are annular metal plates, and holes thereof are formed in the same shape as the axle portion 71c of the axle center portion 71. The first annular plate 72 and the second annular plate 73 are fitted to the axle portion 71c and rotate integrally with the axle portion 71 c.

The first annular plate 72 and the second annular plate 73 are disposed so as to be fitted into portions of the large-diameter gear portion 48a formed one step lower than the upper and

lower surfaces

74, 75. The first annular plate 72 is sandwiched between the enlarged diameter portion 71b of the shaft core portion 71 and the lower surface 74 (convex portion 74a) of the large diameter gear portion 48 a. The second annular plate 73 is sandwiched between the upper surface 75 (convex portion 75a) of the large-diameter gear portion 48a and a deformed portion 71d to be described later.

The inner peripheral edge of the upper surface of the second annular plate 73 is in contact with a deformed portion 54, and the deformed portion 54 is formed by pressing a part of the shaft core portion 71 downward relative to the second annular plate 73 and plastically deforming the pressed part. At this time, the axial hole peripheral portion of the upper surface 75 of the large-diameter gear portion 48a is recessed from the convex portion 75a in contact with the second annular plate 73, and the second annular plate 73 pressed down by the deforming portion 54 elastically deforms so that the inner peripheral edge thereof is tilted downward. Thereby, the second annular plate 73 functions as a disc spring, and biases the large diameter gear portion 48a downward. The biased large-diameter gear portion 48a is pressed by the first annular plate 72, and thereby the large-diameter gear portion 48a rotates integrally with the shaft core portion 71 by frictional resistance generated between the first annular plate 72 and the second annular plate 73. When an external force exceeding the frictional resistance is applied to the large diameter gear portion 48a, the first annular plate 72, the second annular plate 73, and the large diameter gear portion 48a slip, and the large diameter gear portion 48a idles.

In the present embodiment, the eighth gear 48 provided with the overload protection mechanism is directly meshed with the output shaft 91, and the diameter of the gear portion on the eighth gear 48 side is made larger than the diameter of the gear portion on the output shaft 91 side, so that when the output shaft 91 is rotated by the externally applied force, the rotation can be transmitted to the eighth gear 48 while being decelerated. In other words, a torque larger than that applied by the output shaft 91 can be applied to the eighth gear 48. As a result, the torque for operating the overload protection mechanism of the eighth gear 48 can be set to be large, and the influence of the error in the operating torque can be suppressed.

[ shaking prevention Structure of Gear parts ]

Fig. 5 is a plan view of the output gear 60 of the stepping motor 1 ((a) of fig. 5) and a plan view of the output shaft 50 ((b) of fig. 5). In fig. 5 (b), the large diameter gear portion 59 of the output shaft 50 is omitted. Fig. 6 is a side sectional view of the output gear 60 (fig. 6 (a)) and a side view of the output shaft 50 (fig. 6 (b)). Fig. 7 is a plan view (fig. 7 (a)) and a side sectional view (fig. 7 (b)) showing a state in which the output gear 60 is attached to the output shaft 50. Next, the play prevention structure of the output gear 60 will be described with reference to fig. 5 to 7.

(shape of output shaft and Gear Member)

The output shaft 50 of the stepping motor 1 is a metal rotary shaft. The shaft portion 51, which is a portion of the output shaft 50 on the tip end side, extends from the cover plate 12 of the stepping motor 1 into the case 90 of the geared motor G.

As shown in fig. 5 (b), the shaft portion 51 has a shaft-side large diameter portion 52 which is a pair of curved surfaces having the same diameter D and the maximum diameter D. The circumferential surface of the shaft portion 51 other than the shaft-side large diameter portion 52 is formed of a flat surface. As shown in fig. 6 (b), the shaft-side large-diameter portion 52 is formed such that the diameter thereof gradually decreases from below the shaft portion 51 toward above. The shaft portion 51 of the present embodiment is formed by: first, a circular substantially truncated cone-shaped shaft body is produced by cutting, and the other peripheral surface is cut into a flat surface, leaving a portion of the shaft body corresponding to the shaft body side large diameter portion 52.

The output gear 60 is a metal spur gear having a shaft hole 62. The shaft hole 62 of the output gear 60 is formed in substantially the same shape as the shaft portion 51 of the output shaft 50. In addition to the contact portion 63 and the relief groove 64, which will be described later, a shaft hole side large diameter portion 65, which is a pair of curved surfaces that form the maximum diameter W, is provided on a portion of the circumferential surface of the shaft hole 62 that faces the shaft body side large diameter portion 52.

(fixing structure of circumferential position of gear part)

As shown in fig. 5 (a), the shaft hole 62 of the output gear 60 of the present embodiment is formed with a pair of contact portions 63 and relief grooves 64 at positions that are point-symmetrical about the rotational center of the output gear 60. The contact portion 63 is a portion in which the inner surface of the shaft hole 62 protrudes inward, and the relief groove 64 is a portion in which the inner surface of the shaft hole 62 is recessed. The contact portion 63 and the relief groove 64 of the present embodiment are provided at positions corresponding to four corners of the shaft hole 62. As shown in the enlarged view of the portion surrounded by the broken line R in fig. 5 (a), the abutting portion 63 of the present embodiment is a rounded portion provided at the corner of the shaft hole 62.

As described above, the shaft-body-side large diameter portion 52 of the shaft portion 51 is formed so as to gradually decrease in diameter from below toward above. As shown in the enlarged view of the portion surrounded by the broken line E in fig. 5 (b), the corner of the one end 521 (and the other end 522) of the arc of the shaft-side large-diameter portion 52 is not rounded. Therefore, when the output gear 60 is mounted to the shaft portion 51, the one end 521 of the shaft-body-side large diameter portion 52 first comes into contact with the abutment portion 63 of the shaft hole 62. The other end 552 is retracted into the escape groove 64 without contacting the inner surface of the shaft hole 62 (see fig. 7 (a)).

Here, if there is a rattling of the output gear 60 attached to the shaft portion 51, the rattling becomes a cause of noise or an output error at the time of driving the motor. Further, when the position where the shaft hole 62 of the output gear 60 and the shaft portion 51 contact each other is deviated to one side, the axial centers of these components are displaced, and there is a possibility that vibration is generated during driving. In the stepping motor 1 of the present embodiment, the shaft hole 62 of the output gear 60 is provided with the abutting portion 63 whose inner surface protrudes inward, and the one end 521 of the shaft-body-side large-diameter portion 52 of the shaft portion 51 is intentionally brought into contact with the abutting portion 63, whereby the shaft portion 51 and the output gear 60 are reliably brought into contact, and the position where they are in contact can be controlled. Further, by providing the contact portions 63 at positions that are point-symmetrical when viewed in plan from the shaft hole 62 and bringing the arc-shaped one ends 521 of the shaft-body-side large-diameter portions 52 into contact with the contact portions 63, the output gear 60 can be supported in a balanced manner without being biased to one side.

The shaft-side large diameter portion 52 of the present embodiment is formed such that the diameter thereof gradually decreases from below the shaft portion 51 toward above. The shaft-side large diameter portion 52 is a pair of curved surfaces having the maximum diameter D in the circumferential surface of the shaft portion 51. Therefore, when the one end 521 of the arc of the shaft-side large-diameter portion 52 comes into contact with the contact portion 63 and the shaft-side large-diameter portion 52 rotates in the direction of coming off from the contact portion 63 (or when the output gear 60 rotates in the direction of coming off from the one end 521 of the shaft-side large-diameter portion 52), the other end 522 of the arc comes into contact with the inner surface of the shaft hole 62. Thus, for example, when the output gear 60 is tilted up and down when the output gear 60 is attached to the shaft portion 51, the

end portions

521 and 522 of the one shaft-side large-diameter portion 52 are caught in the shaft hole 62 before the

end portions

521 and 522 of the other shaft-side large-diameter portion 52, and the output gear 60 may be fixed in a state of being tilted up and down. Therefore, in the stepping motor 1 of the present embodiment, the escape grooves 64 are separately provided at positions that are point-symmetrical when the shaft hole 62 is viewed in plan, and the other ends 522 of the shaft-body-side large-diameter portions 52 are evacuated into the escape grooves 64, thereby reducing such assembly failures.

In this way, in the stepping motor 1 according to the present embodiment, the shaft portion 51 and the output gear 60 can be concentrically arranged without rattling or tilting by configuring the one end 521 of the shaft-side large-diameter portion 52 of the shaft portion 51 to actively contact the shaft hole 62 of the output gear 60 and the other end 522 of the shaft-side large-diameter portion 52 not to contact the shaft hole 62.

In the stepping motor 1 according to the present embodiment, the diameter D of the portion other than the shaft-side large diameter portion 52 is reduced by configuring the peripheral surface of the shaft portion 51 other than the shaft-side large diameter portion 52 with the flat surface portion 53, but if the diameter D of the shaft-side large diameter portion 52 is maximized on the peripheral surface of the shaft portion 51, the shape of the peripheral surface other than that is not particularly limited to a flat surface.

(Structure for fixing Up and Down positions of Gear Member)

As shown in fig. 6 (a), the shaft hole side large diameter portion 65 of the shaft hole 62 of the output gear 60 is formed such that the diameter W gradually decreases from below the shaft hole 62 toward above. Next, a structure for fixing the vertical position of the output gear 60 will be described with reference to fig. 6.

The shaft hole 62 of the output gear 60 of the present embodiment is a through hole. The shaft-hole-side large-diameter portion 65 of the shaft hole 62 has an upper end aperture φ A of 3.98(4.00-0.02) and a lower end aperture φ E of 4.06(4.00+ 0.06). The thickness T of the output gear 60 in the vertical direction is 3.5 mm.

The shaft 51 of the present embodiment is provided with a taper at its tip end to guide the attachment position of the output gear 60. The diameter φ B of the shaft-body-side large-diameter portion 52 immediately below the taper of the shaft portion 51 (hereinafter, this portion is referred to as "the upper end of the shaft portion 51") is φ 3.96 (4.00-0.04). The diameter φ D of the shaft-side large-diameter portion 52 at the lower end of the shaft portion 51 is φ 4.05(4.00+ 0.05). The diameter φ C of a portion slightly closer to the upper end than the center of the intermediate portion between the upper end and the lower end of the shaft portion 51 is φ 3.98 ± 0.02. The height H of the portion having the diameter φ C of the intermediate portion is set to a height of 4.2mm from the lower end of the shaft portion 51. In the shaft body 51 of the present embodiment, the amount of change in the diameter D per unit length in the vertical direction is smaller than the amount of change in the diameter W of the output gear 60 per unit length in the vertical direction.

As described above, the diameter D of the shaft portion 51 and the hole diameter W of the shaft hole 62 of the output gear 60 are in the following relationship.

T: thickness of output gear < H: height of the portion of the shaft side large diameter portion having diameter phi C

Phi A: the diameter of the upper end of the large-diameter part at the shaft hole side is larger than phi B: diameter of upper end of large diameter part on shaft side

Phi A: the aperture of the upper end of the large diameter part on the shaft hole side is approximately equal to phi C: diameter of middle part of shaft-side large-diameter part

Phi E: the diameter of the lower end of the large diameter part at the shaft hole side is larger than phi D: diameter of lower end of large diameter part on shaft side

In this way, in the stepping motor 1 of the present embodiment, the diameter Φ a of the upper end of the shaft-hole-side large-diameter portion 62 is larger than the diameter Φ B of the upper end of the shaft-body-side large-diameter portion 52, and is almost equal to the diameter Φ C of the substantially middle portion. Therefore, the output gear 60 of the present embodiment is fixed to the shaft portion 51 by its upper end being caught in the middle portion of the shaft-side large diameter portion 52 (see fig. 7 (b)). Further, since the thickness T of the output gear 60 is smaller than the height H of the portion of the shaft-side large-diameter portion 52 that becomes the diameter Φ C, the output gear 60 does not reach the lower end of the shaft portion 51, and is reliably fixed to the intermediate portion. This suppresses the rattling of the output gear 60 more strongly than in the case where the lower end of the output gear 60 is fixed to the shaft portion 51. This effect is particularly remarkable when the shaft portion 51 and the output gear 60 are made of metal as in the present embodiment.

While the embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various changes can be made without departing from the scope of the present invention. For example, in the present embodiment, the number of parts of the entire geared motor G is reduced and the geared motor G is miniaturized by using the stepping motor 1, but in particular, if there is no such requirement or limitation, it is conceivable to use another motor.

Claims

1. An electric motor, comprising:

a gear component; and

a rotating shaft having a shaft portion into which the gear member is fitted,

a shaft-side large diameter portion that is a pair of curved surfaces having the same diameter and the largest diameter is provided at a part of the shaft portion in the circumferential direction,

the shaft-side large diameter portion is formed such that a diameter thereof gradually decreases from a lower side of the shaft portion toward an upper side when one side of the shaft portion in an axial direction is set to be upper and the other side is set to be lower,

in the shaft hole of the gear member, a contact portion whose inner surface protrudes inward and an escape groove whose inner surface is recessed are formed at positions which are point-symmetric when the shaft hole is viewed in the depth direction,

one end of an arc of each of the shaft-side large-diameter portions of the shaft portion inserted into the shaft hole is in contact with the abutting portion, and the other end is retracted into the escape groove.

2. The motor according to claim 1,

the peripheral surface of the shaft portion is flat except for the shaft-side large diameter portion.

3. The motor according to claim 2,

the outer shape of the shaft portion is a shape obtained by cutting the other peripheral surface of a circular truncated cone-shaped shaft body into a flat surface, leaving a portion corresponding to the large diameter portion on the shaft body side.

4. The motor according to any one of claims 1 to 3,

the shaft hole side large diameter portion, which is a portion of the inner surface of the shaft hole facing the shaft body side large diameter portion, is formed such that the diameter of the hole gradually decreases from below the shaft hole toward above.

5. An electric motor as claimed in claim 4, characterized in that

The shaft hole is a through hole,

when a portion between an upper end and a lower end of the shaft-body-side large diameter portion is defined as an intermediate portion of the shaft-body-side large diameter portion,

the diameter of the upper end of the shaft hole side large diameter portion is larger than the diameter of the upper end of the shaft body side large diameter portion and is equal to the diameter of a certain part of the middle portion,

the amount of change in diameter per unit length in the vertical direction of the shaft-side large diameter portion is smaller than the amount of change in diameter per unit length in the vertical direction of the shaft-hole-side large diameter portion.

6. The motor according to claim 5,

the rotating shaft is an output shaft of a built-in driving source,

the output shaft is provided with a bearing portion surrounding the front end of the output shaft and having a gap with the front end.

7. The motor according to claim 6,

a clearance between an outer surface of the output shaft and an inner surface of the bearing portion is larger than a clearance between the output shaft and another bearing portion supporting the output shaft.