JP4679114B2 - Stepping motor. - Google Patents

Description

  The present invention relates to a stepping motor used in an optical disk device or the like.

As such a stepping motor, the one described in Patent Document 1 is known. A stepping motor is used for driving a pickup lens of an optical disc in an optical disc apparatus such as a personal computer because of its characteristic of easily controlling rotation. In order to absorb the thrust force when the pickup lens is driven in the axial direction of the rotating shaft, the stepping motor is provided with a thrust pressurizing unit that pressurizes the rotating shaft in the axial direction. In recent years, along with the demand for thinner optical disk devices, stepping motors are also housed in a space with a limited thickness, so that it is required to reduce the size in the radial direction.
JP-A-8-308167

  However, in such a stepping motor, it is necessary to increase the axial dimension of the rotating shaft in order to ensure sufficient torque while reducing the radial dimension. When the dimension in the axial direction of the stepping motor is increased, the dimension in the axial direction of each part constituting the housing, the rotor, and the stator is increased accordingly, so that it is difficult to mold each part. If the dimensional tolerances in the axial direction of the respective parts accumulate, the rotor and the stator may not fit inside the casing, or there may be play in the axial direction between the rotor, the stator and the casing. In addition, the backlash of the rotor and stator in the housing increases the possibility that backlash will also occur in the thrust pressurization section, which increases the risk that the thrust pressurization section will not be able to generate proper pressurization. There is a problem that the vibration in the axial direction of the rotating shaft becomes large and proper rotation accuracy cannot be obtained.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a stepping motor that can be assembled while absorbing dimensional tolerances in the rotation axis direction of a casing, a rotor, a stator, and a thrust pressurizing portion.

The stepping motor of the present invention includes a rotor disposed on the outer periphery of the rotation shaft, a pair of stators each including a pair of coils disposed so as to sandwich the rotor in the axial direction of the rotation shaft, and applying a rotational force to the rotor, A thrust pressurizing section that pressurizes the rotating shaft in the axial direction, and a casing that houses the rotor, the stator, and the thrust pressurizing section. The casing extends in a cylindrical shape in the axial direction, and the casing main body together is fitted to adjustably in the axial direction at the opening end of the, e Bei a cap having a lid portion for supporting the rotary shaft through the thrust pressurization portion in the axial direction, and the housing main body of the cap The end portion of the housing is provided with a guide portion that contacts the outer surface of the opening end portion of the housing body, and the guide portion is slid in the axial direction on the outer surface of the opening end portion to adjust the position of the cap relative to the housing body. characterized in that it is To.

  In this stepping motor, the axial length of the internal space of the housing can be adjusted by adjusting the position of the cap of the housing in the axial direction. As a result, the rotor, the stator, and the thrust pressurizing portion can be reliably accommodated in the housing while absorbing the dimensional tolerances of the housing, the rotor, the stator, and the thrust pressurizing portion.

  Further, the length of the housing in the axial direction is preferably at least twice the diameter of the housing. As a configuration of the stepping motor for reducing the dimension in the radial direction, for example, a configuration in which a pair of stators are arranged so as to sandwich the rotor in the axial direction and the coils of the stator are arranged in parallel with the rotor in the axial direction is conceivable. . According to this configuration, since the pair of coils and the rotor are juxtaposed in the axial direction, the length in the axial direction of the housing is likely to be, for example, twice or more larger than the length in the radial direction. . In such a stepping motor that is long in the axial direction, in particular, the cumulative dimensional tolerance in the axial direction of each component constituting the motor tends to be large, but according to the present invention, while absorbing this cumulative dimensional tolerance, the rotor, The stator and the thrust pressurizing part can be reliably stored in the housing.

  In addition, an enlarged diameter guide portion in contact with the outer surface of the opening end portion of the housing body may be provided at the end portion of the cap on the housing body side. In this case, when the guide portion is fitted into the opening side end portion of the housing body, the position of the lid portion can be adjusted while sliding the cap in the axial direction, and the motor assembly workability can be improved. .

  Further, the guide portion may be provided with a first cutout portion so that the guide portion of the cap is positioned between two parallel planes in contact with the outer surface of the housing body. In this case, the dimension in the radial direction of the cap is a dimension that fits between the two planes. That is, since the dimension in the radial direction of the cap can be made the same as that of the housing main body, the dimension in the radial direction of the motor is not increased even when the guide portion is provided on the cap, and the motor can be thinned.

  Further, a drive current supply connector protruding from the housing body in the radial direction of the rotating shaft may be further provided, and the guide portion of the cap may be provided with a second notch portion into which the connector is fitted. In this case, the circumferential positioning of the cap is achieved by fitting the connector into the second notch.

  According to the present invention, it becomes possible to assemble a stepping motor while absorbing the dimensional tolerance in the rotation axis direction of the casing, the rotor, the stator, and the thrust pressurizing portion.

  Hereinafter, preferred embodiments of a stepping motor according to the present invention will be described in detail with reference to the drawings.

  A stepping motor 1 shown in FIGS. 1 and 2 is built in an optical disc apparatus and used as a motor for driving a pickup lens that reads data on the optical disc. Since the stepping motor 1 has a cylindrical shape and is housed in a space having a limited thickness in the optical disk device, the diameter is reduced to about 5 mm. The stepping motor 1 has a rotor 5 made of a permanent magnet fixed to the outer periphery of a shaft 3 as a rotating shaft and magnetized alternately with N poles and S poles in the direction of the axis L of the shaft 3. A pair of stators 7, 7 </ b> A are disposed on both sides of the rotor 5. The rotor 5 and the stators 7 and 7A are accommodated in a cylindrical case 9 made of a nonmagnetic material such as brass or stainless steel. Although details will be described later, the case 9 includes a case body (housing body) 91 that extends in a cylindrical shape in the direction of the axis L and has an open rear end portion, and a cap 93 that is fitted to the rear end portion of the case body 91. Consists of.

  Thus, as a result of the stators 7 and 7A being arranged in parallel to the rotor 5 in the direction of the axis L, the diameter of the stepping motor 1 can be reduced. Further, since the diameter of the rotor 5 is small so as to contribute to the reduction in diameter, the required torque of the stepping motor 1 is ensured by increasing the dimension of the rotor 5 in the axis L direction. In this embodiment, the total length of the motor 1 is about 13.5 mm, which is twice or more the diameter, and the stepping motor 1 has a cylindrical shape that extends long in the direction of the axis L.

  The stator 7 includes a coil bobbin 27 around which a coil 25 for generating a magnetic field is wound, and a yoke 29 that accommodates the coil bobbin 27. The yoke 29 includes an inner yoke 31 made of a magnetic material, an outer yoke 33, and a sleeve 21 that couples both of them. The inner yoke 31 and the outer yoke 33 are concentrically connected to both ends of the sleeve 21, respectively.

  The sleeve 21 is disposed between the shaft 3 and the coil bobbin 27 so as to surround the shaft 3 and is formed in a tubular shape extending in the axis L direction. The sleeve 21 has an inner diameter dimension that does not contact the shaft 3 and penetrates the shaft 3. The inner yoke 31 is connected to an end portion of the sleeve 21 on the side close to the rotor 5, and has a disk-like base portion 31 a orthogonal to the axis L, and four fourth portions erected around the base portion 31 a at equal intervals. 1 magnetic pole tooth 31b. The first magnetic pole teeth 31 b extend to a position facing the outer peripheral surface of the rotor 5 so as to surround the rotor 5. The outer yoke 33 is connected to one end of the sleeve 21 on the side far from the rotor 5, and has a disk-like base portion 33 a orthogonal to the axis L, and four second portions erected around the base portion 33 a at equal intervals. And magnetic pole teeth 33b. The second magnetic pole teeth 33b extend to a position facing the outer peripheral surface of the rotor 5 so as to surround the rotor 5, and are positioned so as to enter between the first magnetic pole teeth 31b so as not to contact the first magnetic pole teeth 31b. is doing. As a result, the first magnetic pole teeth 31b and the second magnetic pole teeth 33b are alternately arranged on the outer peripheral surface of the rotor 5 so as to face each other.

  The coil bobbin 27 accommodated in the yoke 29 has a through hole 27a, and the sleeve 21 is penetrated through the through hole 27a. The coil bobbin 27 has a base portion 31a of the inner yoke 31, a base portion 33a of the outer yoke 33, and a first portion. Surrounded by the two magnetic pole teeth 33 b and the sleeve 21, it is accommodated in the yoke 29. A coil 25 is wound around the coil bobbin 27, and the coil 25 is electrically connected to a terminal 27b drawn from between the second magnetic pole teeth 33b. When a pulse current is applied to the coil 25 from the outside through the terminal 27b, the coil 25 generates a magnetic field. The generated magnetic field is transmitted through the sleeve 21, the inner yoke 31 and the outer yoke 33 to the magnetic pole teeth 31 b and 33 b facing the outer peripheral surface of the rotor 5, so that a magnetic field that rotates the rotor 5 is generated. It will be formed around.

  Furthermore, the stator 7A having substantially the same configuration as the stator 7 described above includes a coil bobbin 27A around which a coil 25A for generating a magnetic field is wound, and a yoke 29A that accommodates the coil bobbin 27A. The yoke 29A includes an inner yoke 31A made of a magnetic material, an outer yoke 33A, and a sleeve 21A that couples both of them. The configurations of the coil bobbin 27A, yoke 29A, inner yoke 31A, outer yoke 33A, and sleeve 21A are the same as those of the coil bobbin 27, yoke 29, inner yoke 31, outer yoke 33, and sleeve 21, respectively. The detailed explanation is omitted.

  As described above, the pair of stators 7 and 7A are disposed facing each other in the direction of the axis L with the rotor interposed therebetween so that the magnetic pole teeth 31b and 33b are shifted at a predetermined phase. A drive current supply connector 30 including terminals 27b and 27Ab protruding from the stators 7 and 7A is provided to protrude from the side surface of the case main body 91, and the stepping motor 1 is connected to an external power supply via the connector 30. Drive current is supplied from (not shown). A drive current from the outside is supplied to the coils 25 and 25A via the terminals 27b and 27Ab of the connector 30, and the energizing direction is sequentially switched, whereby the rotor 5 is given a rotational force and the rotor 5 and the shaft 3 are applied. Is rotated stepwise about the axis L.

  The shaft 3 protrudes outside from the opening at the front end of the case 9 while passing through the sleeve 21 of the stator 7, and a lead screw portion 11 is formed on the shaft 3 outside the case 9. The lead screw portion 11 can convert the rotation of the shaft 3 into driving in the direction of the axis L of a pickup lens (not shown) as a driven member. The front end of the case 9 of the stepping motor 1 is connected to a screw frame 12 that is positioned on a plane that is in contact with the outer peripheral surface of the case 9 and extends along the lead screw portion 11. The screw frame 12 pivotally supports the tip of the lead screw portion 11 by a bearing portion 14 provided at the tip.

  When the pickup lens is driven by the lead screw portion 11, the shaft 3 receives a thrust force as a reaction from the lead screw portion 11. Therefore, in order to absorb this thrust force generated during driving, a thrust pressurizing portion 15 is accommodated in the sleeve 21A behind the shaft 3. In the thrust pressurizing portion 15, a spherical ball 17, a rear pivot 19 and a coil spring 20 are arranged in this order from the side closer to the shaft 3.

  The front side of the ball 17 is disposed so as to come into contact with the peripheral edge portion of the bearing recess 3 a formed at the rear portion of the shaft 3, and the rear side of the ball 17 is in contact with the rear pivot 19. With such a structure, the sleeve 21 </ b> A functions as a thrust bearing for the rear pivot 19, and the shaft 3 can be smoothly rotated about the axis L with respect to the rear pivot 19. The rear pivot 19 is slidably supported in the direction of the axis L while being in contact with the sleeve 21 </ b> A, and the rear end is supported by one end of the coil spring 20. The other end of the coil spring 20 is in contact with a lid portion 93a provided on the cap 93 of the case 9, and the coil spring 20 is biased toward the rear pivot 19 while being supported by the lid portion 93a in the axis L direction. Is granted. With such a configuration of the thrust pressurizing portion 15, the shaft 3 is supported in the direction of the axis L by the lid portion 93 a of the cap 93 via the thrust pressurizing portion 15, and the lead screw portion is driven by the urging force of the thrust pressurizing portion 15. The tip of 11 is pressed against the bearing portion 14.

  In such a stepping motor 1, the inner yokes 31 and 31A, the outer yokes 33 and 33A and the sleeves 21 and 21A constituting the stators 7 and 7A, the casing main body 91 and the cap 93 constituting the casing 9 are Molded by deep drawing with a press. Since these components are long in the direction of the axis L and are very small components, it is difficult to obtain high dimensional accuracy by press working. Since the stators 7 and 7A are arranged in the axis L direction together with the rotor 5 in the housing 9, the dimensional tolerances of the components of the stators 7 and 7A are accumulated in the axis L direction, so that the stators 7 and 7A are accumulated. In some cases, the rotor 5 may not fit inside the housing 9, or the stators 7, 7 </ b> A may rattle in the direction of the axis L within the housing 9. The stepping motor 1 has a long cylindrical shape in the axis L direction such that the length in the axis L direction is twice or more of the diameter, and the above-described components are also long in the axis L direction.

  In order to solve this problem, the case 9 of the stepping motor 1 includes a case main body 91 and a cap 93 fitted to the rear end portion of the case main body 91. When the case 9 is assembled, the cap 93 is fitted to the case main body 91 while being adjusted in position in the axis L direction. At this time, the fitting position of the cap 93 is adjusted in the direction of the axis L so that the lid portion 93h of the cap 93 is in contact with the rear end portion of the stator 7A, and the stators 7, 7A and the rotor 5 Are stored without gaps in the direction of the axis L. After the fitting, the case main body 91 and the cap 93 are connected, for example, by welding.

  The side wall portion of the cylindrical case body 91 is provided with a cut portion 91b cut from the opening side end portion 91a side, and the connector 30 projects out of the case 9 through the cut portion 91b. ing.

  As shown in FIGS. 3 and 4, the cap 93 has the same outer diameter and inner diameter as the case main body 91, and has a cylindrical portion 93 f opened at one end. At the center of the disc-shaped lid portion 93h located at the other end of the cylindrical portion 93f, a spring receiving portion 93a having a circular recess as viewed from the inside is formed, and this spring receiving portion 93a is formed of the coil described above. The shaft 3 is supported through the thrust pressurizing portion 15 by bringing the spring 20 into contact therewith. A guide portion 93b that protrudes in the direction of the axis L and is in contact with the outer surface of the opening-side end portion 91a of the case body 91 is provided at the opening-side end portion of the cylindrical portion 93f. The guide portion 93b has an outer diameter larger than that of the cylindrical portion 93f, and has an inner diameter that fits the opening side end portion 91a of the case main body 91 with an interference fit.

  When the cap 93 is fitted into the case main body 91, the guide portion 93 b comes into contact with the outer surface of the opening-side end portion 91 a of the case main body 91. The cap 93 is guided by the guide portion 93b so as to slide in the direction of the axis L while maintaining concentricity with the case main body 91. At this time, the dimension in the direction of the axis L of the cap 93 is such that the lid 93h of the cap 93 is in contact with the rear end of the stator 7A. The dimension is such that a gap G (see FIGS. 1 and 2) is formed between the opening-side end portion 91a. As a result, the lid portion 93h of the cap 93 is brought into contact with the rear end of the stator 7A, so that the stator 7, 7A and the rotor 5 can be accommodated in the case 9 without gaps in the axis L direction. Such a play in the case 9 can be suppressed.

  Further, since the guide portion 93b can move to a position deeper than the position of the connector 30, a notch portion for connector (second notch portion) 93s for fitting the connector 30 is formed in the guide portion 93b. Has been. Since the connector notch 93s has a width that fits into the connector 30, the cap 93 can be positioned in the circumferential direction by fitting the connector notch 93 s into the connector 30.

  The guide portion 93b is formed with a pair of cutout portions for height reduction (first cutout portions) 93u and 93t at positions facing each other in the radial direction. Due to the notches 93u and 93t, the guide portion 93b is in contact with the outer peripheral surface of the cylindrical portion 93f (that is, also in contact with the outer peripheral surface of the case main body 91) between the two flat surfaces S1 and S2. , S2 is positioned so as not to protrude from S2. The planes S1 and S2 are planes parallel to the direction in which the connector 30 protrudes from the case 9 and the axis L direction. Therefore, although the diameter of the stepping motor 1 is increased by providing the guide portion 93b on the cap 93, by forming the notch portions 93u and 93t for decreasing the height, the direction perpendicular to the direction in which the connector 30 protrudes is formed. The outer diameter of the motor 1 in the direction is not increased. As a result, the stepping motor 1 can be reduced in thickness, and it is easy to fit in a space having a limited thickness in the optical disc apparatus.

  In this manner, by enabling the cap 93 to move in the axis L direction with respect to the case main body 91, the position of the lid portion 93h can be adjusted in the axis L direction before joining them together by welding or the like. Therefore, according to the stepping motor 1, the stator 7, 7A, the rotor 5 and the thrust pressurizing portion 15 are securely accommodated in the housing 9 while absorbing the dimensional tolerance in the axis L direction of the stator 7, 7A. Thus, the case main body 91 and the cap 93 can be connected. Further, by adjusting the position of the cap 93 in the direction of the axis L so that the lid portion 93h is in contact with the rear end of the stator 7A, the stators 7 and 7A can be stored in the case 9 without any gap in the direction of the axis L. Thus, rattling in the case 9 of the stators 7 and 7A can be suppressed. Further, in the case 9 assembled in this way, the thrust pressurizing portion 15 is also stored so that there is no backlash, and the coil spring 20 is stored in a state of being contracted by an appropriate amount. The urging force generated by the thrust pressurizing unit 15 becomes appropriate, and appropriate rotation accuracy of the motor 1 can be obtained.

  Since the case main body 91 and the guide portion 93b are dimensioned to fit with an interference fit, before the connection by welding or the like, the biasing force of the coil spring 20 is suppressed only by the fit and the motor 1 Temporary assembly can be performed. Since the inspection can be performed by driving the motor 1 in this temporary assembly state, even when a drive failure is found in the inspection, the case 9 can be opened again to correct the internal defect. As a result, the defect rate of the stepping motor 1 can be reduced and the yield can be improved.

  The present invention is not limited to the above-described embodiment. For example, the notch portion 93 s for the connector may not be provided in the guide portion 93 b of the cap 93. As an example in this case, as shown in FIGS. 5 to 7, the guide portion 53 b of the cap 53 is formed with a pair of notch portions 53 t and 53 u for height reduction at opposing positions. In the cap 53, the dimension of the motor is not increased in the direction in which the notch portions 53t and 53u for height reduction are formed. In the stepping motor having the cap 53, the cap 53 moves in the direction of the axis L in a range where the guide portion 53b does not reach the connector position, and the position of the lid portion 53h can be adjusted.

  Further, the present invention may be applied not only to the circular stepping motor 1 having a circular cross section but also to a so-called oval stepping motor 61 as shown in FIG. Note that, among the components of the stepping motor 61, the same or equivalent components as those of the stepping motor 1 are denoted by the same reference numerals. The case 8 of the stepping motor 61 includes a case main body 81 and a cap 83 having a guide portion 83b. When the guide portion 83b of the cap 83 is fitted into the opening-side end portion 81a of the case main body 81, the lid portion 83h is axial. The position can be adjusted in the L direction. Further, the guide portion 83b is formed with a height reduction cutout portion 83t, and the size of the motor in the direction in which the height reduction cutout portion 83t is formed is not increased.

It is sectional drawing which shows embodiment of the stepping motor which concerns on this invention. It is a perspective view which shows the stepping motor of FIG. It is a perspective view of a cap. It is a bottom view of the cap of FIG. It is a perspective view which shows the other cap applied to the stepping motor which concerns on this invention. It is a side view which shows the cap of FIG. It is a bottom view which shows the cap of FIG. It is a perspective view which shows other embodiment of the stepping motor which concerns on this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,61 ... Stepping motor, 3 ... Shaft (rotating shaft), 5 ... Rotor, 7, 7A ... Stator, 8, 9 ... Case (housing), 81, 91 ... Case main body (housing main body), 81a, 91a ... opening side end, 53, 83, 93 ... cap, 93a ... spring receiving part, 53b, 83b, 93b ... guide part, 53t, 53u, 83t, 93u, 93t ... notch for reducing height (first notch (Notch part), 93 s ... notch part for connector (second notch part), 15 ... thrust pressurizing part, 30 ... connector for driving current supply, L ... axis, S1, S2 ... plane.

Claims (5)

A rotor formed on the outer periphery of the rotating shaft, a pair of stators each including a pair of coils disposed so as to sandwich the rotor in the axial direction of the rotating shaft, and applying a rotational force to the rotor; and the rotating shaft includes a thrust pressurization unit for pressurizing in the axial direction, the rotor, and a housing for accommodating the stator and the thrust pressurization unit,
The housing is
A casing body extending in a cylindrical shape in the axial direction;
A cap having a lid portion that is fitted to the opening side end portion of the housing body so as to be positionally adjustable in the axial direction and supports the rotating shaft in the axial direction via the thrust pressurizing portion. e,
A guide portion that contacts an outer surface of the opening-side end portion of the housing body is provided at an end portion of the cap on the housing body side, and the guide portion is disposed on the outer surface of the opening-side end portion in the axial direction. A stepping motor in which the position of the cap with respect to the housing body is adjusted by sliding on the casing .   2. The stepping motor according to claim 1, wherein a length of the casing in the axial direction is at least twice a diameter of the casing.   The end portion on the housing body side of the cap is provided with an enlarged guide portion that contacts an outer surface of the opening-side end portion of the housing body. Stepper motor.   The first notch portion is provided in the guide portion so that the guide portion of the cap is positioned between two parallel planes in contact with the outer surface of the housing body. The stepping motor described. A drive current supply connector that projects from the housing body in the radial direction of the rotary shaft;
5. The stepping motor according to claim 3, wherein the guide portion of the cap is provided with a second notch portion into which the connector is fitted.

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