JP2007325327A - Motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor which can surely prevent the wobbling of a rotating shaft even if there is employed a structure which supports both axial ends of the rotating shaft by using a bearing. <P>SOLUTION: In the output-side bearing 4 of the stepping motor 1, an external peripheral part 25a of a round-bar shaped protruding part 25 of the rotating shaft 20 is axially supported by the internal side face 41a of a round recess 41, and the accuracy of co-axiality with the rotating shaft 20 is high limited in the machining of the external peripheral part 25a. The end face 25b of the round-bar shaped protruding part 25 is constituted of a spherical face, and this spherical face is supported by the bottom 41b of the round recess 41. Since the spherical face consistently contributes to the support in a thrust direction, the wobbling is not caused at the rotating shaft 20 even if the center of the spherical face is displaced from the center of the rotating shaft 20. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a motor that is rotated and output by a rotating shaft.

  As a motor for moving a moving object such as an optical head used in a CD player or a DVD player at high speed, for example, a stepping motor in which a lead screw is formed on the outer peripheral surface of the output side portion of the rotating shaft is used. In such a stepping motor, a permanent magnet is attached to the non-output side portion of the rotating shaft to form a rotor, and a stator is disposed at a position facing the permanent magnet in the radial direction. Here, both ends of the rotating shaft are rotated by an output side bearing held by a counter plate portion of a frame fixed to the output side of the stator and an anti-output side bearing disposed on the counter-output side of the stator. Supported as possible.

  As such a bearing, for example, as shown in FIG. 4A, a bearing using a steel ball 300 is used. In this case, a concave cone portion 37 'is formed on both the output side and the non-output side end surfaces of the rotary shaft 30', and the concave cone portion 37 'and the concave cone portion 39' of the bearing 38 'are provided between them. A structure in which a steel ball 300 is sandwiched between the two is employed.

As the bearing, as shown in FIG. 4B, a sphere portion 36 ″ is formed on both the output side and the non-output side end of the rotary shaft 30 ″, and these sphere portions 36 ″ are formed. Has also been proposed (see, for example, Patent Document 1).
JP 2000-358350 A

  When manufacturing the rotary shaft 30 'as shown in FIG. 4A, a lead screw is formed on the outer peripheral surface of the round bar while rotating the round bar while the round bar is held by the chuck of the machine tool. . However, since the concave conical portions 37 ′ on both end surfaces of the rotating shaft 30 ′ cannot be formed as they are, after forming the concave conical portions on one of the both end surfaces of the rotating shaft 30 ′, the round bar is cut off with a cutting tool. Then, the chuck is re-chucked to form a concave cone portion on the other end face. For this reason, center misalignment of the conical portions on both ends of the rotating shaft 30 'occurs. For this reason, in the configuration shown in FIG. 4A, the rotation center of the rotation shaft 30 'when finished, the outer periphery of the rotation shaft alone, and the concave conical portion 39' at the rotation shaft center of the lead screw flank surface. Since it is unavoidable that a deviation error occurs at the center position between the two, when the rotary shaft 30 ′ rotates, the rotary shaft 30 ′ shakes.

  Further, in the rotating shaft 30 ″ having the structure shown in FIG. 4B, the same portion in the vicinity of the axis of the spherical portion 36 ″ is supported by the concave conical portion 39 ″ of the bearing 38 ″ in both the thrust direction and the radial direction. Therefore, there is a problem that the swing of the rotating shaft 30 ″ cannot be completely prevented as in the configuration shown in FIG. 4A for the following reason. That is, the rotation of the structure shown in FIG. When manufacturing the shaft 30 ″, one of the spherical portions 36 ″ on both sides can be formed together with the lead screw while holding the round bar with the chuck of the machine tool. As for the ball part, it is impossible to process the ball part to the vicinity of the axis while holding the round bar with the chuck of the machine tool. Rework and smell in the other sphere To become processing the near axis is supported by the "凹錐 portion 39 of the" bearing 38, an error is generated in the bulb 36 "center position between. In addition, the area of the sliding portion between the spherical portion 36 ″ and the concave conical portion 39 ″ of the bearing 38 ″ increases, and the shaft loss increases.

  In view of the above problems, an object of the present invention is to provide a motor that can reliably prevent the rotation of the rotating shaft even when a structure in which both ends of the rotating shaft are supported by bearings is employed.

  In order to solve the above-described problems, in the present invention, a rotor including a rotating shaft and a permanent magnet fixed to the rotating shaft, a stator disposed on the outer periphery of the permanent magnet, and a non-output side end of the rotating shaft In the motor having a non-output side bearing that supports the output portion and an output side bearing that supports the output side end portion of the rotating shaft, one of the anti-output side bearing and the output side bearing is the rotation A first bearing having a circular recess that supports an outer peripheral portion of the shaft end of the shaft in a radial direction on an inner peripheral side surface parallel to the axis of the rotating shaft, and the other bearing is formed at the shaft end of the rotating shaft. It consists of a 2nd bearing provided with the concave cone part which supports the spherical part made by the conical surface.

  In the present invention, one of the two shaft ends of the rotating shaft is supported by the inner peripheral side surface of the circular recess of the first bearing in the radial direction at the outer peripheral portion of the shaft end. Unlike manufacturing in the vicinity, when manufacturing a rotating shaft, while processing the shaft end supported by the second bearing while holding the round bar with the chuck of the machine tool, forming the lead screw, etc. It can be done together. Therefore, the portion of the rotating shaft that is supported in the radial direction by the first bearing has a high degree of coaxiality with the rotating shaft, as in the portion of the rotating shaft that is supported by the second bearing. The shake can be surely prevented.

  In the present invention, of both shaft ends of the rotating shaft, a shaft end supported by the first bearing is formed with a round bar-like projecting portion having an outer peripheral surface parallel to the axis of the rotating shaft, A configuration in which the outer peripheral portion of the round bar-like protruding portion is supported in the radial direction by the inner peripheral side surface of the circular concave portion can be employed.

  In this case, of both shaft ends of the rotating shaft, the end surface of the shaft end supported by the first bearing is a spherical surface, and a structure is adopted in which the spherical surface is supported in the thrust direction by the bottom of the circular recess. May be. In this case, since the spherical surface only contributes to support in the thrust direction, even if the center of the spherical surface is deviated from the center of the rotating shaft, the rotating shaft is not shaken.

  In the present invention, a spherical projecting portion is formed at a shaft end supported by the first bearing among both shaft ends of the rotating shaft, and the spherical projecting portion is formed in a radial direction by an inner peripheral side surface of the circular recess. It is preferable that it is supported and supported in the thrust direction by the bottom of the circular recess. When configured in this way, the rotating shaft is supported in the radial direction at the outer peripheral portion of the outer surface of the spherical protruding portion and supported in the thrust direction near the axis of the rotating shaft, but the portion supported in the thrust direction Since the accuracy of the degree of coaxiality with the portion supported by the second bearing on the rotating shaft and the rotating shaft is high, the swinging of the rotating shaft can be reliably prevented. Further, when the shaft end supported by the first bearing is a spherical projecting portion, the area of the sliding portion is smaller than when the shaft end is a round bar-shaped projecting portion. The frictional resistance can be reduced. Therefore, the life of the motor can be extended. Further, since the generation of sound is reduced by reducing the area of the sliding portion, the motor can be silenced.

  In the present invention, a frame for holding the output side bearing is fixed to the output side of the stator, and a bearing holder for holding the counter output side bearing is fixed to the counter output side of the stator. It is preferable that an urging member for urging the rotating shaft toward the output side is disposed. If comprised in this way, since a bearing supports a rotating shaft reliably, the shake | deflection of a rotating shaft can be prevented.

  In the present invention, either the non-output-side bearing or the output-side bearing may be configured by the first bearing, and either may be configured by the second bearing. However, it is preferable that the non-output side bearing is composed of the second bearing, and the output side bearing is composed of the first bearing. The first bearing needs to have a circular recess extending to a position deeply overlapping the outer peripheral portion of the rotating shaft, while the second bearing does not extend to the outer peripheral portion of the rotating shaft, even if the end surface of the rotating shaft is not extended. It only needs to be supportable. Therefore, the second bearing can be shorter in the axial direction than the first bearing, and is therefore suitable for being arranged on the motor body side where the stator is located.

  In this invention, it is preferable that the lead screw is formed in the outer peripheral surface of the output side part of the said rotating shaft. If a deviation occurs in the center of the rotation shaft, the feed amount of a feed-side member such as a rack placed on the lead screw is not stable, and undulation occurs at a rate of 1 degree per rotation of the rotation shaft. It cannot be sent accurately. However, according to the present invention, the swinging of the rotating shaft can be reliably prevented, and the lead screw feed accuracy is improved.

  In the present invention, the portion of the rotating shaft that is supported in the radial direction by the first bearing is similar to the portion of the rotating shaft that is supported by the second bearing. Shaking of the shaft can be reliably prevented.

  A motor to which the present invention is applied will be described below with reference to the drawings. 1A, 1B, and 1C are a half sectional view of a stepping motor to which the present invention is applied, a rear view when the stepping motor is viewed from the non-output side, and an explanatory view of a rotating shaft.

(Configuration of stepping motor)
1A and 1B, a stepping motor 1 according to the present embodiment generally includes a stator 5, a rotor 2, a motor case 50 covering the periphery of the stator 5, and a frame fixed to the output side of the stator 5. 7. The rotor 2 includes a rotating shaft 20 and two permanent magnets 28 and 29 fixed at positions adjacent to each other on the opposite side of the rotating shaft 20 in the axial direction. In each of the magnets 28 and 29, N poles and S poles are alternately magnetized in the circumferential direction. The stator 5 includes two stator sets 51 and 52 that are disposed so as to overlap in the axial direction at positions facing the permanent magnets 28 and 29 on the outer peripheral side. The two stator sets 51, 52 are respectively an outer stator core 51a, 52a, bobbins 51c, 52c around which coils 51b, 52b are wound, and inner stator cores 51d, 52d sandwiching the bobbins 51c, 52c between the outer stator cores. The outer stator cores 51 a and 52 a and the inner stator cores 51 d and 52 d are provided with a plurality of pole teeth arranged on the inner peripheral portion of the stator 5.

  As shown in FIGS. 1A and 1C, the rotary shaft 20 includes a small-diameter shaft portion 22 and a large-diameter shaft portion 21, and permanent magnets 28 and 29 are fixed to the small-diameter shaft portion 22. . In the rotary shaft 20, the rear end portion of the small-diameter shaft portion 22 constitutes a counter-output side shaft end 20 a that protrudes from the motor case 50 to the counter-output side. On the other hand, the large diameter shaft portion 21 protrudes from the output side end plate 50b of the motor case 50, and a lead screw 26 is formed on the outer peripheral surface thereof.

  The frame 7 includes a fixed plate portion 72 fixed to the output side end plate 50b of the motor case 50, a counter plate portion 71 facing the fixed plate portion 72 on the output side, and the counter plate portion 71 and the fixed plate. And a connecting plate portion 70 for connecting the portion 72.

  Further, the stepping motor 1 of the present embodiment includes the counter-output side bearing 3, the bearing holder 6, and the biasing member 9 on the counter-output side of the rotating shaft 20, and includes the output-side bearing 4 on the output side. The configuration of the bearing 4, the non-output side bearing 3, the bearing holder 6, the biasing member 9, and the like will be described in detail below with reference to FIG.

(Bearing configuration)
2A and 2B are an explanatory diagram of an output side bearing and an anti-output side bearing of the stepping motor shown in FIG. As shown in FIGS. 1A and 1B, in the stepping motor 1 of this embodiment, the counter-output side shaft end 20 a of the rotary shaft 20 is supported by the counter-output side bearing 3 fitted to the bearing holder 6. The output side shaft end 20 b of the rotary shaft 20 is supported by the output side bearing 4 held by the counter plate portion 71 of the frame 7.

  As shown in FIG. 2A, a small-diameter round bar-like protruding portion 25 having an outer peripheral surface parallel to the axis L of the rotating shaft 20 is formed at the output-side shaft end 20b of the rotating shaft 20. The side bearing 4 is configured as a first bearing that supports the outer peripheral portion 25 a of the round bar-shaped protruding portion 25 on the inner peripheral side surface 41 a of the circular recess 41 in the radial direction. Here, the inner peripheral side surface 41 a of the circular recess 41 is parallel to the axis L of the rotating shaft 20. Further, the end surface 25 b of the round bar-like projecting portion 25 is a spherical surface, and this end surface 25 b (spherical surface) is supported in the thrust direction by the bottom 41 b of the circular concave portion 41 of the output side bearing 4. Note that grease as a lubricant is injected inside the circular recess 41.

  As shown in FIG. 2 (b), a spherical projecting portion 24 is formed at the counter-output side shaft end 20 a of the rotary shaft 20, and the counter-output side bearing 3 is located in the vicinity 24 a of the axis L of the spherical projecting portion 24. Is configured as a second bearing that supports the conical surface 31a of the concave cone portion 31 in the radial direction and the thrust direction. In addition, grease as a lubricant is injected inside the concave cone portion 31.

  A bearing holder 6 is fixed to the counter-output side end plate 50a of the motor case 50, and a through-hole 60 in which the counter-output side bearing 3 is mounted is formed in the bearing holder 6. Further, a biasing member 9 made of a metal plate is disposed on the opposite output side with respect to the bearing holder 6. A plurality of claw portions 91 extend from the outer peripheral edge of the urging member 9, and the plurality of claw portions 91 wrap around from the outer peripheral side of the bearing holder 6 to the opposite surface side and engage with the bearing holder 6. The biasing member 9 is fixed to the bearing holder 6. A leaf spring portion 92 is cut and raised on the biasing member 9, and the leaf spring portion 92 biases the non-output side bearing 3 toward the output side. For this reason, the rotating shaft 20 is urged toward the output side bearing 4, and rattling of the rotating shaft 20 is prevented.

(Rotating shaft machining method)
Of the manufacturing method of the stepping motor 1 configured as described above, when the rotary shaft 20 is manufactured, the round bar is rotated while the round bar is held by the chuck of the machine tool, and a lead screw is provided on the outer peripheral surface thereof. 26 is cut with a cutting tool, and a spherical projecting portion 24 is formed on the non-output side end face 20a.

  Next, in the round bar material, the outer peripheral part in the vicinity held by the chuck is cut with a cutting tool to form the outer peripheral part 25a of the round bar-like protruding part 25 and the like.

  Next, after cutting the round bar material with a cutting tool so that the outer peripheral side of the end face 25b of the round bar-shaped protruding portion 25 becomes a spherical surface, the tip side of the round bar with the parting tool (processing as the rotary shaft 20 is completed) Section). Alternatively, when the tip end side of the round bar material (the part where the processing as the rotating shaft 20 has been completed) is cut with a parting tool, the round bar material is cut so that the end surface 25b of the round bar-shaped protruding portion 25 becomes a spherical surface. The rotating shaft 20 obtained in this way is sent to the assembly of the rotor 2 as it is or after performing a predetermined finishing process. Here, as the finishing process, for example, the center side (in the vicinity of the axis L) of the end face 25b of the round bar-like protruding portion 25 is finished to be a spherical surface.

(Main effects of this form)
As described above, in the present embodiment, in the output-side bearing 4 configured as the first bearing, the round bar-shaped protruding portion 25 (output-side shaft end 20b) of the rotary shaft 20 on the inner peripheral side surface 41a of the circular recess 41. If the outer peripheral portion 25a is supported in the radial direction and the processing of the outer peripheral portion 25a is different from the processing in the vicinity of the axis L, when manufacturing the rotary shaft 20, a round bar is used with the chuck of the machine tool. While being held, the processing can be performed together with the processing of the shaft end supported by the non-output-side bearing 3 (formation of the spherical protruding portion 24) and formation of the lead screw 26. Therefore, the portion (the outer peripheral portion 25a of the round bar-like protruding portion 25) that is supported in the radial direction by the output side bearing 4 (first bearing) on the rotary shaft 20 is supported by the non-output side bearing 3 on the rotary shaft 20. Like the shaft end (spherical protruding portion 24), the accuracy of the coaxiality with the rotating shaft 20 is high. That is, since the deviation of the center of the rotating shaft 20 can be prevented, the shake due to the eccentricity of the rotating shaft 20 can be reliably prevented. Further, when a deviation occurs in the center of the rotary shaft 20, the feed amount of a feed-side member (not shown) such as a rack placed on the lead screw 26 is not stable, and is once per rotation of the rotary shaft 20. Since swells occur at a rate, the sheet cannot be fed with high accuracy. However, according to the present embodiment, the swinging of the rotating shaft 20 can be reliably prevented, and the feed accuracy of the lead screw 26 is improved. . Furthermore, when the rotary shaft 20 is processed, the portion supported by the non-output side bearing 3 and the output side bearing 4 and the lead screw 26 can be processed at the same time. Therefore, the coaxiality of the formed lead screw 26 is high.

  Further, in this embodiment, the end surface 25b of the round bar-like projecting portion 25 is configured as a spherical surface, and this spherical surface is supported in the thrust direction by the bottom 41b of the circular recess 41. However, such a spherical surface is only in the thrust direction. Therefore, even when the center of the spherical surface constituting the end face 25b is deviated from the center of the rotating shaft 20, the rotating shaft 20 does not shake.

  Furthermore, either the non-output side bearing 3 or the output side bearing 4 may be configured by the first bearing, and either may be configured by the second bearing. In this embodiment, the counter-output side bearing 3 is the second bearing. The output side bearing 4 is composed of a first bearing. The first bearing needs to have the circular recess 41 extending to a position overlapping with the outer peripheral portion 25a of the rotating shaft 20, while the second bearing does not extend to a position overlapping with the outer peripheral portion of the rotating shaft. As long as the end surface of the rotating shaft 20 can be supported. Therefore, since the second bearing can shorten the axial dimension as compared with the first bearing, the second output bearing 3 disposed on the motor main body side where the stator 5 is located is provided as in the second embodiment. Therefore, the axial dimension of the motor body can be shortened.

(Other embodiments)
In the above embodiment, a round bar-like protruding portion 25 is formed on the output side shaft end 20b of the rotary shaft 20 and its end surface 25b is a spherical surface. However, as shown in FIG. 3, the output side shaft end 20b of the rotary shaft 20 is spherical. A protruding portion 25 'may be formed. Also in this case, in the output side bearing 4, the outer peripheral portion 25 a ′ of the spherical protrusion 25 ′ of the rotary shaft 20 is supported in the radial direction by the inner peripheral side surface 41 a of the circular recess 41, and the tip portion 25 b ′ (top) is circular. What is necessary is just to employ | adopt the structure supported by the bottom part 41b of the recessed part 41 in a thrust direction. Even in this configuration, the portion supported in the thrust direction (the outer peripheral portion 25a ′ of the spherical protrusion 25 ′) is connected to the shaft end supported by the non-output-side bearing 3 on the rotating shaft 20 and the rotating shaft 20. Since the accuracy of the coaxiality is high, it is possible to reliably prevent the rotation shaft 20 from shaking. In addition, when the shaft end supported by the output side bearing 4 is a spherical projecting portion 25 ′, the area of the sliding portion is narrower than when the shaft end is a round bar-shaped projecting portion 25, The frictional resistance at the sliding portion can be reduced. Therefore, the life of the stepping motor 1 can be extended. Further, since the generation of sound is reduced by reducing the area of the sliding portion, the stepping motor 1 can be silenced.

  Moreover, in the said embodiment, although the spherical protrusion part 24 was formed in the anti-output side shaft end 20a of the rotating shaft 20, if the end surface is spherical, it will protrude in a round bar shape as shown in FIG. The shape may be sufficient.

(A), (b), (c) is a half sectional view of a stepping motor to which the present invention is applied, a rear view when the stepping motor is viewed from the non-output side, and an explanatory view of a rotating shaft. (A), (b) is explanatory drawing of the output side bearing of the stepping motor shown in FIG. 1, and explanatory drawing of a non-output side bearing. It is explanatory drawing which shows the form of another 2nd bearing used for the stepping motor to which this invention is applied. It is explanatory drawing of the bearing used for the conventional stepping motor.

Explanation of symbols

1 Stepping motor 2 Rotor 3 Non-output side bearing (second bearing)
4 Output side bearing (first bearing)
5 Stator 6 Bearing holder 7 Frame 9 Energizing member 20 Rotating shaft 24 Spherical protruding portion 25 Round bar-shaped protruding portion 26 Lead screw 28, 29 Permanent magnet 31 Concave cone 41 Circular concave

Claims (7)

A rotor including a rotating shaft and a permanent magnet fixed to the rotating shaft; a stator disposed on an outer periphery of the permanent magnet; a counter-output-side bearing that supports a counter-output-side end of the rotating shaft; and the rotation In a motor having an output side bearing that supports the output side end of the shaft,
One of the non-output side bearing and the output side bearing includes a circular recess that supports the outer peripheral portion of the shaft end of the rotary shaft in the radial direction on the inner peripheral side surface parallel to the axis of the rotary shaft. A motor comprising the first bearing, and the other bearing comprising a second bearing having a concave conical portion that supports a spherical portion formed at a shaft end of the rotating shaft with a conical surface. In claim 1,
Of the shaft ends of the rotating shaft, a shaft end supported by the first bearing is formed with a round bar-like protruding portion having an outer peripheral surface parallel to the axis of the rotating shaft,
A motor characterized in that an outer peripheral portion of the round bar-like projecting portion is supported in a radial direction by an inner peripheral side surface of the circular recess. In claim 2,
Of both shaft ends of the rotating shaft, the end surface of the shaft end supported by the first bearing is a spherical surface, and the spherical surface is supported in the thrust direction by the bottom of the circular recess. Motor. In claim 1,
Of the shaft ends of the rotating shaft, a spherical projecting portion is formed at the shaft end supported by the first bearing,
The spherical protruding portion is supported in the radial direction by the inner peripheral side surface of the circular recess, and is supported in the thrust direction by the bottom of the circular recess. In any of claims 1 to 4,
A frame for holding the output side bearing is fixed to the output side of the stator,
A bearing holder that holds the counter-output side bearing is fixed to the counter-output side of the stator,
The motor according to claim 1, wherein a biasing member that biases the rotating shaft toward the output side is disposed in the bearing holder. In any of claims 1 to 5,
The non-output-side bearing comprises the second bearing, and the output-side bearing comprises the first bearing. In any one of Claims 1 thru | or 6.
A motor having a lead screw formed on an outer peripheral surface of an output side portion of the rotating shaft.

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