JP3379885B2 - Stepping motor and manufacturing method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a stepping motor and a manufacturing method thereof . More specifically, the present invention relates to improvement of a bearing structure of a motor rotating shaft in a stepping motor.

[0002]

2. Description of the Related Art A stepping motor 101 having a lead screw portion 103 formed on a motor rotating shaft 102 is
As shown in FIG. 5, there is a structure in which one shaft end 111 of the motor rotation shaft 102 is supported by a thrust bearing 104. In this case, the motor rotating shaft 102 is further supported in the radial direction by a radial bearing 105 made of metal, resin or the like, and is prevented from eccentrically rotating.
It should be noted that the rotor magnet 1 faces the motor rotating shaft 102 so as to face the stator portion 106 with a slight gap.
07 is stuck.

The stepping motor 101 is also provided with a leaf spring 108 that abuts on the other shaft end 112 of the motor rotating shaft 102. The leaf spring 108 urges the motor rotating shaft 102 to urge the motor rotating shaft 102 to move. It prevents rattling in the axial direction. Further, a stopper 109 is provided to prevent the motor spring shaft 102 from coming off due to the plate spring 108 being excessively bent due to an impact or the like.

[0004]

However, in the above stepping motor 101, a sliding loss occurs when the motor rotating shaft 102 and the radial bearing 105 slide, so that the torque of the stepping motor 101 and the high speed of the stepping motor 101 are increased. Responsiveness can be difficult to improve. Further, since the leaf spring 108 is fixedly attached to the outside of the motor case 110 by welding and a thrust pressure is applied to the motor rotating shaft 102 from the outside of the stepping motor 101, the leaf spring 108 can be removed and disassembled. It is difficult to replace parts and perform maintenance. Further, the motor rotating shaft 10
Since the stopper 109 for preventing 2 from coming off is a separate component, the number of components increases.

Therefore, the present invention provides a stepping motor and a manufacturing method thereof in which a bearing structure for receiving a motor rotating shaft is improved, the number of parts is reduced, and a biasing member is detachable, and sliding loss is reduced. The purpose is to

[0006]

In order to achieve the above object, the invention according to claim 1 is such that a lead screw portion is formed on a motor rotating shaft protruding from a stator portion, and at least one of the motor rotating shafts is a thrust bearing. In a stepping motor that is supported by two bearings and biases the motor rotation shaft in the axial direction by a spring, one thrust bearing of the two bearings has a curved contact surface with which the motor rotation shaft contacts. None the bearing body has, along with allowing movement in the axial direction of the bearing body, and that includes a guide portion for the movement of the guide, and the inner diameter is equal to the inner diameter of the stator portion <br/> guide member, the The guide member is attached from the rear side and biases the bearing body in the axial direction toward the other bearing, and the guide member is fixed to the stator portion.

Therefore, the motor rotating shaft rotates in a state where the contact area between the shaft end of the motor rotating shaft and the bearing having the curved contact portion is small and sliding loss is small. Also,
When a force is applied to the motor rotating shaft in the axial direction, the bearing body that supports the shaft end moves in the axial direction together with the motor rotating shaft. The bearing body moved in the axial direction is returned to its original position because it is urged by the spring of the urging plate.

In the stepping motor according to the second aspect, the guide member is made of metal and is fixed to the stator portion by welding.
Therefore, it is possible to join the stator part and the guide member by welding in a state where the mandrel-shaped jig is used for centering. Then, the guide member fixed to the stator portion by welding guides the movably provided bearing member.

Further, in the stepping motor according to the present invention, a flange portion is formed on the peripheral edge of the guide member, and an engaging portion for engaging with the flange portion is formed on the biasing plate, and the engaging portion is formed. The portion is engaged with the flange portion to fix the urging plate. Therefore, the urging plate is detachably attached to the guide portion only by attaching the engaging portion to the flange portion of the guide member, and the spring is brought into contact with the bearing body to axially move the bearing body and the motor rotating shaft. Urge to.

Further, in the stepping motor of the fourth aspect, the other bearing is a thrust bearing. Therefore, the motor rotating shaft rotates while being supported by the two thrust bearings. The invention according to claim 5 is
The motor's rotary shaft protruding from the motor
And at least one of the motor rotation shafts is a thrust shaft.
It is supported by two bearings, and the motor rotation shaft is axial
Manufacture of stepping motors with spring bias
In the method, the thrust bearing of one of the two bearings is
Bearing body in which the contact surface with which the rotary shaft of the rotor contacts is curved
And allow the axial movement of the bearing body and
And a bearing member having a guide portion for guiding
With a biasing plate that biases the spring toward the other bearing,
Moreover, the inner diameter of the guide member is equal to the inner diameter of the stator.
The inner diameter of these guide members and stator
Using a jig for centering with an outer diameter equal to
Guide part with the core of the guide member and stator part aligned
The material is fixed to the stator part.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The structure of the present invention will be described below in detail based on an example of an embodiment shown in the drawings.

FIG. 1 shows an embodiment of the stepping motor of the present invention. In this stepping motor 1, a lead screw portion 4 is formed on a motor rotating shaft 3 protruding from a stator portion 2, and the motor rotating shaft 3 is supported by two bearings 5 and 6, at least one of which is a thrust bearing. The motor rotating shaft 3 is axially biased by a spring. In this embodiment, thrust bearings are used for both the two bearings 5 and 6, and the thrust bearing 5 allows the motor rotating shaft 3 to rotate.
The front side shaft end of the above is supported by the thrust bearing 6 at the rear side shaft end. Further, one thrust bearing 6 is a bearing body 7 having a curved contact surface with which the motor rotating shaft 3 abuts, and a guide for allowing the bearing body 7 to move in the axial direction and guiding the movement. Guide member 8 having a portion 8a
And a biasing plate 9 that biases the bearing body 7 in the axial direction by a spring, and the guide member 8 is fixed to the stator portion 2.

The stator portion 2 includes a first stator 21 and a second stator 21.
Each of the stator 22, the third stator 23, and the fourth stator 24, and each pole tooth 21a, 22 provided in each stator
a, 23a, 24a, a coil 25 with a donut-shaped coil bobbin inserted between the first stator 21 and the second stator 22, a third stator 23, and a fourth stator 2
4 and a coil 26 with a doughnut-shaped coil bobbin inserted therein. As shown in FIG. 1, each stator forms a cylindrical inner peripheral surface having an inner diameter dimension d.

A "U" -shaped frame 16 for attaching the stepping motor 1 to various devices is fixed to the stator portion 2 on the side of the motor rotating shaft 3 protruding from the stator portion 2. The frame 16 is provided with a shaft through hole 16a through which the motor rotating shaft 3 penetrates, and further, a thrust bearing 5 for supporting the front side shaft end of the motor rotating shaft 3 is mounted in a mounting hole 16b. The inner diameter of the shaft through hole 16a is set smaller than the outer diameter of the rotor magnet 17 described later and larger than the outer diameter of the motor rotating shaft 3.

A cylindrical rotor magnet 17 is fixed to the motor rotating shaft 3. In addition, a contact surface that contacts the curved contact surface of the bearing body 7 is formed at the rear shaft end of the motor rotating shaft 3. Although the shape of the contact surface is not particularly limited, for example, in the case of the present embodiment, a conical concave portion 3b for receiving a steel ball 19 described later is provided. Further, a conical concave portion 3a having a conical shape is also provided at the front shaft end of the motor rotating shaft 3.

The lead screw portion 4 formed on the motor rotating shaft 3 is similar to a conventional lead screw, and a slider 31 engaged with the lead screw portion 4 is moved in the axial direction as the motor rotating shaft 3 rotates. It has the function of moving. The moving direction of the slider 31 is controlled by switching the rotating direction of the motor rotating shaft 3.

The bearing body 7 constituting the thrust bearing 6 is provided with a curved contact surface with which the conical flange portion 3b of the motor rotating shaft 3 abuts. The curved contact surface is not particularly limited, but in the case of the present embodiment, for example, it is constituted by the spherical surface of the steel ball 19, and the bearing body 7 contacts the conical concave portion 3b of the motor rotation shaft 3. It is provided with one steel ball 19 and a steel ball holder 20 for accommodating the steel ball 19.

As shown in FIG. 2, the steel ball holder 20 has a columnar circular recess 20a for accommodating the steel ball 19, and a radial projection for preventing the bearing body 7 from rotating in a radial direction. The three rotation preventing protrusions 20b arranged in
A movement limiting protrusion 20c provided so as to project to the rear side in the axial direction in order to prevent the leaf spring portion 9a of the biasing plate 9 described below from being excessively bent. Further, a circular convex portion 20d surrounding the circular concave portion 20a is provided around the circular concave portion 20a to prevent the shaft end of the motor rotating shaft 3 from being disengaged in the radial direction and to collect the oil accumulated in the circular concave portion 20a. It prevents the water from scattering and drying. The outer diameter dimension of the steel ball holder 20 is formed to be equal to the inner diameter dimension d of the inner peripheral surface of the stator portion 2 so that the motor rotating shaft 3 described later can be easily aligned. As the steel ball holder 20, it is preferable to use a resin molded product from the viewpoints of reducing the weight and improving the slidability between the steel ball 19 and the guide member 8. However, the present invention is not limited to this, and depending on the case, For example, a metal product may be used.

A guide member 8 constituting the thrust bearing 6
As shown in FIG. 3, is a circular plate body, and a guide portion 8a is formed in the center thereof to allow the bearing body 7 to move in the axial direction and guide the movement. The inner diameter of the guide portion 8a is equal to the outer diameter of the steel ball holder 20 fitted in the guide portion 8a, and in the present embodiment, is equal to the inner diameter dimension d of the cylindrical inner peripheral surface formed on the stator portion 2. . Further, the guide portion 8a is provided with relief portions 10 at three positions at equal intervals in the circumferential direction, which prevent the leaf spring portion 9a of the biasing plate 9 and the guide portion 8a from coming into contact with each other. Although the shape of the escape portion 10 is not particularly limited, for example, in the case of the present embodiment, a notch portion 10a extending in the radial direction and an inclined portion 10b provided on the outer peripheral side of the notch portion 10a are formed. ing. Also,
A hook 9b of a biasing plate 9 to be described later is provided on the periphery of the guide member 8.
The flange portions 8b hooked and engaged with are provided at four positions at equal intervals in the circumferential direction in a size capable of accommodating the hook 9b. The edge portion of the flange portion 8b is chamfered so that the hook 9b can be easily attached and detached. In the present embodiment, the metal guide member 8 is fixedly provided by welding at a predetermined position on the rear side of the stator portion 2.

The biasing plate 9 is attached to the guide member 8 from the rear side and biases the bearing body 7 in the axial direction by a spring. As shown in FIGS. 1 and 4, the urging plate 9 is provided with a leaf spring portion 9a that constantly abuts on the bearing body 7 to urge the bearing body 7. Although the number and shape of the leaf spring portions 9a are not particularly limited, for example, in the case of the present embodiment, the three leaf spring portions 9a are attached such that the amount of cutting and raising increases from the outer periphery toward the central portion. It is formed by cutting and raising from the force plate 9. However, the present invention is not limited to this, and the shape of the leaf spring portion 9a may be cut and raised from the central portion toward the outer periphery, or a plate of another member may be attached to the urging plate 9 to attach the leaf spring portion 9a. It may be formed. Further, as illustrated, the leaf spring portion 9 of the present embodiment
The a is formed by cutting and raising so that the flat plate portion 9c other than the leaf spring portion 9a is connected at the central portion of the biasing plate 9. When the guide member 8 moves axially rearward and comes into contact with the urging plate 9, the flat plate portion 9c restricts the movement of the steel ball holder 20, and the steel ball holder 20 and the motor rotation. The shaft 3 is prevented from penetrating rearward. That is,
The flat plate portion 9c of the urging plate 9 serves as a stopper that restricts the amount of movement of the steel ball holder 20 and the motor rotating shaft 3 in the axial direction. In the present embodiment, the above-mentioned movement limiting protrusion 20c contacts the flat plate portion 9c to limit the amount of movement of the bearing body 7. Therefore, the leaf spring portion that urges the bearing body 7 is limited. 9a is also the movement limiting protrusion 2
It does not bend beyond the height of 0c. Therefore, the leaf spring portion 9a becomes fatigued, and the bent leaf spring portion 9a is urged by the urging plate 9.
It prevents the label sticking to the surface of the sticker from sticking to the seal surface.

Further, a hook 9 which engages with the flange portion 8b of the guide member 8 and serves as an engaging portion for fixing and attaching the urging plate 9 to the guide member 8 is provided on the peripheral edge of the urging plate 9.
Four b are provided at equal intervals in the circumferential direction. An appropriate roundness is provided at the base of the hook 9b to provide elasticity. A label indicating the rating of the stepping motor 1 may be attached to the rear surface of the urging plate 9.

The other thrust bearing 5 has the same structure as the bearing body 7 of the thrust bearing 6 described above, and one steel ball 19 with which the conical recess 3a of the motor rotating shaft 3 abuts, and this steel ball 19 A bearing body 18 having a steel ball holder 20 for housing The bearing body 18 has a collar 5a larger than the inner diameter dimension of the mounting hole 16b of the frame 16 and is provided with the frame 1
Since it is attached to No. 6, it does not come off in the axial direction. It should be noted that the thrust bearing 5 may be configured to be movable in the axial direction like the thrust bearing 6 and to urge the motor rotating shaft 3 in the axial direction.

According to the stepping motor 1 configured as described above, the motor rotating shaft 3 is supported by the two bearings 5 and 6, and the contact surfaces of the bearing bodies 7 and 18 that contact the shaft ends are made of steel balls. Since the curved surface shape is formed by the surface of 19, the radial bearing for supporting the motor rotary shaft 3 in the radial direction can be eliminated, and the sliding loss generated between the motor rotary shaft 3 and the radial bearing can be eliminated. . Therefore, it is possible to improve the torque and the high-speed response when the motor rotating shaft 3 is rotated and the slider 31 is moved.

The bearing body 7 which supports the motor rotating shaft 3 at its shaft end is movable in the axial direction, and the motor rotating shaft 3 is urged in the axial direction by the leaf spring portion 9a of the urging plate 9. Therefore, when a thrust load is applied to the motor rotating shaft 3, the bearing body 7 moves in the axial direction and absorbs this thrust load. Further, the movement limiting protrusion 20c provided on the bearing body 7 contacts the flat plate portion 9c of the urging plate 9 to limit the amount of movement of the bearing body 7 in the axial direction. There is no need to install a stopper.

Further, the stepping motor 1 of this embodiment
Since the biasing plate 9 is attached to the guide member 8 by engaging the hook 9b with the flange portion 8b, the biasing plate 9 can be easily attached to and detached from the guide member 8. The biasing plate 9 and the bearing body 7 can be removed to replace the parts of the stepping motor 1 and perform maintenance. Further, since the guide member 8 is provided with the flange portion 8b, it is not necessary to form a hole in the motor case body to provide a concave portion.

Further, since the guide member 8 is provided with a relief portion 10 and the leaf spring 9a is brought into contact with the steel ball holder 20 so as not to come into contact with the guide member 8, a spacer is provided or the leaf spring portion 9a is provided. It is possible to urge the thrust bearing 6 without forming the throttle shape.

The stepping motor 1 of this embodiment is also used.
Since the metal guide member 8 is used, it is possible to join the stator portion 2 and the guide member 8 by welding in a state where the stator portion 2 and the guide member 8 are aligned using a mandrel-shaped jig. As a result, the guide member 8 can be easily fixed to the stator portion 2 by welding, and the labor and cost for attaching the guide member 8 can be reduced. Here, in the present embodiment, the outer diameter dimension of the steel ball holder 20 of the bearing body 7 and the inner diameter dimension of the guide portion 8 a are set to the stator portion 2.
Since it is formed so as to be equal to the inner diameter dimension d of the cylindrical inner peripheral surface of, the part of the centering cylinder having the outer diameter dimension d is inserted into the stator portion 2 and the guide member 8 is If the stator portion 2 is welded in a state in which it is fitted to the portion of the tubular body that is not inserted, the center axis of the stepping motor 1 and the center of the guide member 8 can be easily aligned. However, these diameters do not necessarily have to be the same as the inner diameter dimension d of the stator portion 2, and in that case, of course, the guide member 8 and the stator portion 2 are aligned with each other using a jig or the like. It is possible.

Further, in the stepping motor 1, the rotor bearing such as the motor rotating shaft 3 is inserted into the stator portion 2 and then the thrust bearing 6 is attached, and the rotor portion is inserted from the rear side of the stator portion 2. Can be installed in this way. Therefore, the rotor portion can be attached from the rear side, and even in the stepping motor 1 without the frame 16, the thrust bearing 5 is located on the extension of the central axis of the motor rotating shaft 3 in the member to which the stepping motor 1 is attached. The stepping motor 1 can be attached to the stepping motor 1.

The above-described embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention. For example, although the structure of the stepping motor 1 has been described in the present embodiment, it is of course possible to use the structure of the present invention for a general motor other than the stepping motor.

[0030]

As is apparent from the above description, in the stepping motor according to the invention described in claim 1, the thrust bearing of one of the two bearings has a curved contact surface with which the motor rotating shaft abuts. A bearing member, a guide member having a guide portion that allows the bearing member to move in the axial direction and guides the movement, and a biasing plate that biases the bearing member toward the other bearing by a spring. In addition, since the guide member is fixed to the stator portion, the amount of eccentricity of the motor rotating shaft is reduced. This eliminates the radial bearing that supports the motor rotating shaft in the radial direction, and eliminates the sliding loss that has occurred between the motor rotating shaft and the radial bearing. Moreover, since the contact surface of the bearing body is formed into a curved surface shape, it is possible to further reduce the sliding loss when the motor rotating shaft rotates and improve the torque and the high-speed response. Well
In addition, the center axis of the stepping motor and the center of the guide member
Can be easily matched.

Furthermore, in the stepping motor according to the second aspect of the present invention, the guide member is made of metal and is fixed to the stator portion by welding, so that the guide member can be easily attached to the stator portion. Therefore, the cost for mounting can be reduced.

Further, in the stepping motor according to the third aspect of the present invention, a flange portion is formed on the peripheral edge of the guide member, and an engaging portion for engaging the flange portion is formed on the biasing plate. Since the urging plate is fixed by engaging the joint portion with the flange portion, the urging plate and the bearing body can be easily removed, and maintenance such as replacement of parts can be easily performed.

Further, in the stepping motor according to the fourth aspect of the present invention, since the other bearing is a thrust bearing, the thrust loads in both directions applied to the motor rotating shaft can be supported by both thrust bearings. Thereby, the bidirectional thrust load applied to the motor rotation shaft can be absorbed. Further, the stepping motor according to claim 5 is manufactured.
In the method, the thrust bearing includes a bearing body, a guide member, and a biasing plate.
And the inner diameter of the guide member
Make sure that the inner diameter is the same and the cores are fixed together.
The center axis of the stepping motor and the guide
The center of the member can be easily matched. Also,
A radial bearing that supports the motor shaft in the radial direction
Lost between the rotary shaft of the motor and the radial bearing.
It is possible to eliminate sliding loss. Moreover, the bearing body
Since the contact surface is curved, the motor rotation shaft
Torque and high-speed response with less sliding loss
Can be improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a stepping motor of the present invention.

2A and 2B are views showing a steel ball holder of a bearing body, in which FIG. 2A is a longitudinal sectional view and FIG. 2B is a side view.

FIG. 3 is a view showing a guide member, (A) is III-III.
A longitudinal sectional view taken along a line, (B) is a side view.

FIG. 4 is a view showing a biasing plate, (A) is a longitudinal sectional view,
(B) is a side view.

FIG. 5 is a vertical cross-sectional view showing a conventional stepping motor.

[Explanation of symbols]

1 stepping motor 2 Stator part 3 motor rotation axis 4 Lead screw part 5 Thrust bearing (other bearing) 6 Thrust bearing 7 Bearing body 8 Guide member 8a Guide part 8b Flange part 9 bias plate 9b Hook (engagement part) 19 Steel ball (contact surface)

Claims (5)

(57) [Claims] 1. A lead screw portion is formed on a motor rotating shaft protruding from a stator portion, the motor rotating shaft is supported by two bearings at least one of which is a thrust bearing, and the motor rotating shaft is axially arranged. In a stepping motor that is biased by a spring, one of the thrust bearings of the two bearings has a bearing body having a curved contact surface with which the motor rotation shaft abuts, and an axial movement of the bearing body. It has a guide part that allows it and guides its movement , and the inner diameter is the inner diameter of the stator part.
If equal the guide member, Installing the rear on the guide member
And a biasing plate for axially biasing the bearing body toward the other bearing in the axial direction , and fixing the guide member to the stator portion. motor. 2. The stepping motor according to claim 1, wherein the guide member is made of metal and is fixed to the stator portion by welding. 3. A flange portion is formed on the peripheral edge of the guide member, and an engaging portion for engaging the flange portion is formed on the biasing plate, and the engaging portion is engaged with the flange portion. The stepping motor according to claim 1 or 2, characterized in that the biasing plate is fixed. 4. The stepping motor according to claim 1, wherein the other bearing is a thrust bearing. 5. The motor rotating shaft protruding from the stator part
By forming the lead screw part,
Supported by two bearings, at least one of which is a thrust bearing
So that the motor rotating shaft is axially biased by a spring.
In the method of manufacturing a stepping motor,
Align one of the thrust bearings with the motor rotation shaft.
Bearing body having a curved contact surface and a shaft of the bearing body
A guide that allows movement in a certain direction and guides the movement.
A guide member having an id portion, and the bearing body on the other side.
And a biasing plate that biases the spring toward the bearing, and
Make the inner diameter of the guide member equal to the inner diameter of the stator.
The inner diameter of these guide members and stator
Using a centering jig with an outer diameter equal to La Guy
The guide member and stator core together.
Switch member is fixed to the stator portion.
Manufacturing method of stepping motor.