JP4822214B2 - Inner rotor type vibration motor - Google Patents

Description

  The present invention relates to a small-diameter cylindrical vibration motor, and more particularly to an inner rotor type DC brushless motor for generating vibration in which an eccentric weight is attached to a rotor magnet.

  In recent years, in our daily lives, various electronic devices are equipped with small motors as drive sources. For each device, motor functions, miniaturization, weight reduction, and high output are achieved according to the purpose of use. Technology development has been made.

  Similarly, mobile phones that are wireless communication devices are also equipped with this small motor. For example, in a quiet public place where people gather, such as museums and concert halls, and in business meetings or important meetings, mobile phones A small motor for generating vibrations (hereinafter referred to as a vibration motor if necessary) that alerts the incoming call by vibrate vibration when the sudden ringtone of the sound may cause a great deal of trouble to the people around you. ) Is used.

  In the case of the vibration motor, in general, an eccentric weight that is an eccentric center of gravity is attached to one end of the output rotation shaft to be driven, and an uneven centrifugal force due to the center of gravity position of the weight swinging along with the rotation operation of the rotor portion The mobile phone is vibrated as a whole, and as these mobile phones become more widespread, their mounting rate and use frequency are increasing day by day.

  Most of the vibration motors have the eccentric weight arranged at one end of the output rotation shaft outside the motor housing case, but some of them are arranged at a part of the rotor inside the housing case. For example, in the small motors described in Patent Documents 1 and 2 shown below, “the permanent magnet rotor itself has an unbalanced weight structure with an inertial body, and the rotating motor is given a vibrating action by the unbalanced moment of the permanent magnet rotor. And “an unbalanced weight structure constituted by an inertial body having a rotor portion in which one side in the radial direction of the permanent magnet is partially removed and a nonmagnetic lightweight material is attached to the removed portion. There is a prior application gazette that clearly states.

  Thereby, “a vibration motor can be provided by the simple eccentric center of gravity structure of the permanent magnet rotor without attaching an extra inertia body on the shaft extension serving as the end of the rotating shaft of the rotor”.

JP-A-5-304743 JP-A-5-304744

  The vibration motors described in Patent Documents 1 and 2 have an unbalanced weight structure in which a magnet (indicated as a permanent magnet in the patent document) and the rotor itself is an inertial body, and vibrate by the unbalanced moment of the rotating rotor magnet. However, the smaller the diameter of the motor body, the smaller the diameter of the magnet, and considering the magnetic imbalance of the magnet itself, the magnetic starting force of the rotor magnet structure can be obtained. In addition, even when viewed from the specific gravity of the magnet material, the effect of the rotor itself as a weight inertial body is reduced.

  In other words, in the current small motor in which the rotor magnet itself arranged inside the cylindrical housing case is not of high specific gravity and has a magnetically unbalanced structure, and the outer diameter of the motor is reduced to about 4 mm. In this case, the rotor magnet itself cannot obtain a sufficient starting force for driving the motor, and there is a fear that the rotor magnet hardly starts.

  The present invention has been made to solve the above-described problems, and has a rotor structure that rotates while always maintaining the magnetic balance of the rotor magnet and effectively using the magnetic flux between the field coils. Another object of the present invention is to provide a vibration motor in which an eccentric weight serving as a heavy inertial body having a high specific gravity is arranged at an eccentric position of a rotor effective for obtaining a vibration force. Furthermore, it aims at providing the vibration motor which can aim at the further diameter reduction and size reduction, without reducing the rotational efficiency as a small motor.

In order to solve the above-mentioned problem, in the invention according to claim 1,
A field coil for generating an electric magnetic field is arranged on the inner wall of the housing case of the cylindrical motor, and the stator side bearings are arranged at both ends of the cylindrical housing case. In the inner rotor type cylindrical motor
The magnet shape of the rotor portion supported by the rotating shaft is a plate-shaped magnet having a substantially rectangular cross section in which both ends of the ineffective magnetic flux range portion positioned in a direction orthogonal to the magnetic pole direction of the radially anisotropic magnet are cut out equally. And the rotor is balanced with respect to the rotation center axis.
On the other hand, as an unbalanced weight of the rotor part, a weight inertial body made of a non-magnetic material that fills one side of the evenly cut space of the magnet is separately provided as an eccentric weight and eccentric to the rotor part. It is an inner rotor type vibration motor.

In the invention according to claim 2, in the invention according to claim 1,
The driving of the vibration motor is based on a two-phase or three-phase DC brushless driving system.

In the invention according to claim 3, in the invention according to claim 1 or 2,
The combination of the magnet constituting the rotor part and the weight inertial body is a rare earth magnet made of an Nd magnet or Sm magnet and an eccentric weight made of a tungsten alloy having a specific gravity of 12 or more of a nonmagnetic material. It is an inner rotor type vibration motor.

Moreover, in invention of Claim 4, in the small motor of Claims 1-3,
A rotating shaft is arranged at the center of gravity of the rotor magnet, and an eccentric weight, which is a heavy inertial body, is fixedly attached to the magnet side by being directly bonded to the outer peripheral surface of the magnet or covered entirely with a resin mold. The inner rotor type vibration motor is characterized.

As described above, according to the invention described in claim 1,
For example, even when space constraints are imposed on the inner rotor due to a request to reduce the diameter of the vibration motor, etc., it is necessary at startup while maintaining the dynamic rotor balance of the rotating rotor magnet. The basic operational characteristics of the drive output as a small motor can be sufficiently obtained without impairing the effective magnetic flux for obtaining a sufficient torque.

  In addition, as the unbalanced weight, it is possible to arrange a weight inertial body made of a nonmagnetic material with a higher specific gravity than the magnet material in a separately cut and lightened part of the magnet shape, so that the entire rotor part The center-of-gravity radius from the center of the rotation axis increases, and a more efficient vibration force can be obtained during operation. In other words, it is possible to attach an eccentric weight of high specific gravity material to a part of one side of the magnet that is effective for the eccentric center of gravity while maintaining the original magnetic characteristics of the small motor. In addition, a rotor portion having an eccentric center of gravity with excellent space efficiency can be configured.

According to the invention of claim 2,
The drive system of the vibration motor is based on the two-phase or three-phase DC brushless drive system, and by using the brushless system, there is no physical electric rectification mechanism consisting of brushes and commutators, and a long-life motor structure is possible. Become. With brushless, there is no worry about life due to contact failure due to mechanical wear of the sliding contact part, and the wear of the rotating sliding part, that is, the part life of the bearing part that supports the rotor part at both ends is substantially reduced. Reliability is improved, and the electric rectification mechanism is electrically processed by a driving circuit called a driver.

  As for the optional selection of the two-phase or three-phase drive system, for example, in the case of two phases, the design of the drive circuit is easy, but the mechanical means of how the position when the rotor is stopped can be fixed. Is required. In general, the design scale of the drive circuit for starting the rotor part is larger in the three-phase than in the two-phase, and in the case of the three-phase, it is a component whether it is sensor drive using Hall elements or sensorless drive. It affects the development cost in terms of points and circuit design. In brushless driving, whether to install a part of the dedicated drive circuit on the drive circuit board side on the device side that is the basic base or mount it on the vibration motor as an external drive circuit depends largely on the development design.

According to the invention of claim 3,
Since the combination of the magnet and the weight inertial body constituting the rotor part is a rare earth magnet made of Nd magnet or Sm magnet and an eccentric weight made of a tungsten alloy of nonmagnetic material with a specific gravity of 12 or more, one magnet In this case, the rotating magnetic flux required by the small and small rotor magnet in the cylindrical motor housing case can be effectively used while the magnet is reduced in size.

  In addition, by using a high specific gravity tungsten alloy with a specific gravity of 12 or more for the eccentric weight, space saving and the most efficient weight inertia can be achieved as an unbalanced weight of the rotor part that fits sufficiently in the small and small diameter cylindrical motor housing case. Functions as a body. Therefore, the center-of-gravity radius from the rotation axis center of the entire rotor as the rotation axis center can be increased, and a sufficient vibration force can be obtained. Naturally, a high specific gravity tungsten alloy close to a specific gravity of 18 is the most suitable weight for the eccentric weight, and is effective for obtaining a vibration force. Moreover, the thing of specific gravity about 13-16 of the range which can be manufactured with a sintered alloy can fully be used. However, materials with a specific gravity of 12 or more and less than 13 that can be mixed and molded with other resin components can be used to some extent as weight inertia bodies, but materials with a specific gravity of less than 12 can reduce the size of the product. Considering it, vibration force cannot be obtained sufficiently.

According to the invention of claim 4,
A rotating shaft is arranged at the center of gravity of the rotor magnet itself, and an eccentric weight, which is a heavy inertial body, is either directly bonded to the outer peripheral surface of the magnet or entirely covered with a resin mold and integrated, so that an extremely small diameter is obtained. It is possible to assemble the entire rotor portion without applying mechanical stress to the rotating shaft. In addition, the attachment and integration of the magnet and the eccentric weight with respect to the shaft which is the rotating shaft as the rotor portion can reduce productivity and cost by a resin molding method using an injection molding technique. The rare earth magnet can be integrally formed with a resin magnet in addition to a sintered magnet, and the degree of freedom in designing the combined shape is expanded in accordance with the shape of the eccentric weight.

<Embodiment 1>
The configuration of the embodiment according to the present invention will be described below with reference to FIGS. In this embodiment, as an example of the inner rotor type motor, a brushless driving cylindrical vibration motor in which an eccentric weight is attached to a rotor magnet will be described as an example.

  FIG. 1 is a schematic sectional view showing an example of the best embodiment of the present invention. As shown in FIG. 1 (b), the shape of the magnet 2 of the inner rotor portion is an ineffective magnetic flux located in a direction orthogonal to the magnetic pole direction of the anisotropic magnet material oriented in the N / S magnetic field in the radial direction. It is a plate-like magnet having a substantially rectangular cross section in which a range portion is cut evenly at both ends. The material composition is preferably a Nd—Fe—B or Sm—Co rare earth magnet. The rare earth magnet is excellent in magnetic properties and can cope with size reduction due to a reduction in diameter. As is clear from FIG. 1 (b), the magnet 2 itself has a symmetrical cross-sectional shape with respect to the rotation center axis 6, and the rotor balance is maintained dynamically.

  On the other hand, as a means for unbalance of the rotor portion, a separate circular portion of the magnet 2 having a substantially rectangular shape is separately cut, and one portion of the lightened weight (that is, one region where the arc is cut) is used as a magnet material. As a weight inertial body made of a non-magnetic material having a higher specific gravity, a rod-shaped eccentric weight 3 is integrally attached to the magnet 2 as a weight that causes the rotor portion to have an eccentric center of gravity. In other words, the magnetic characteristics of the magnet 2 in a small motor remain unchanged, and an eccentric weight 3 made of a material with a high specific gravity can be attached to a part of one side of the magnet 2 that is effective for eccentric gravity. The center-of-gravity radius can be increased, and an eccentric rotor portion excellent in space can be configured as an inner rotor type vibration motor. The higher the specific gravity of the tungsten alloy is, the closer the specific gravity is to 18.

  On the outer periphery of the rotor part, the field coil 4 fixedly arranged on the inner wall of the housing case 5 is arranged with high accuracy through a magnetic gap. At this time, as shown in FIG. 1 (a), the rotor portion includes a bearing 8 on the small diameter portion side where the rotating shaft 6 is narrowed down in the housing case 5 and a bearing on the end flange 7 on the other end of the housing case 5. 8 and are supported by both shafts. At the same time, the support in the thrust direction of the rotor portion is regulated and held by the thrust receiver 9 on the end flange 7 side and the liner 10 on the other side.

  On the other hand, the power feeding portion of the field coil 4 has a terminal 11 that connects and relays the tap wire of the field coil 4 attached to one end portion of the cylindrical field coil 4 and is fed to the end flange by a power feeding terminal 12 using a flexible substrate. 7 is pulled out. The power supply terminal 12 is connected to a drive circuit (not shown) on the device body side. The drive system in this embodiment is a three-phase sensorless drive brushless motor. The brushless configuration does not have a physical rectification mechanism including a brush and a commutator, and a long-life motor structure is possible. With brushless, due to the characteristics of the motor, there is no risk of a decrease in service life due to mechanical wear of the electrical sliding contact part. The service life of the component is longer than that of the brush / commutator as the electrical sliding contact portion, and as a result, the reliability of the motor is improved. The physical rectification mechanism is electrically processed instead by a drive circuit called a driver. ,

  In the vibration motor 1 shown in FIG. 1, there is no output shaft outside the housing case 5 in appearance, and tungsten is attached to one end of the output rotation shaft 106 like the conventional vibration motor 100 shown in FIG. It is also different in appearance from a vibration motor structure of a type to which a semi-cylindrical eccentric weight 103 formed of a high specific gravity sintered alloy or the like is attached.

Next, the magnetic effect of the magnet 2 in the present embodiment will be described using the schematic radial cross-sectional shape of FIG.
For example, as shown in FIG. 3 (a), in the case of an anisotropic magnet having NS magnetic poles in the radial direction of a cylindrical magnet 22, the effective magnetic flux range (R) for the opposing field coil 24 is generally In particular, one side is about 100 to 130 degrees, and the remaining one side is about 50 to 80 degrees is a non-effective magnetic flux range portion (W). The non-effective magnetic flux range portion (W) of the magnet 22 is a magnetic action effect. It is a part that is not so much related to

  Therefore, even if the ineffective magnetic flux range portion (W) positioned in a direction orthogonal to the N / S magnetic pole direction is cut evenly at both ends, there is substantially no influence on the extreme deterioration in the characteristics of the magnet. Therefore, in this embodiment, as shown in FIG. 3B, the shape of the magnet 2 is processed into a plate-like magnet having a substantially rectangular cross section, and the rotor balance at the time of the rotation operation is rotated with respect to the rotation shaft 6 that is the rotation center axis. It was attached to keep it.

  As a result, the basic operation characteristics of the drive output as a small motor can be sufficiently obtained without losing the effective magnetic flux for obtaining the rotational torque required at the time of starting the motor for the small volume of the magnet 2. be able to. The actually driven inner rotor type vibration motor showed the same or better performance than the vibration motor of the conventional size in terms of various characteristics at startup and vibration amount during rotation.

<Embodiment 2>
FIG. 2 shows an example of another embodiment of the present invention. The shape of the magnet 2 of the inner rotor portion in FIG. 2A shown in the schematic cross-sectional view is the same as that shown in FIG. 1 with respect to the magnetic pole direction of the anisotropic magnet material oriented in the N / S magnetic field in the radial direction. This is a plate-like magnet having a substantially rectangular cross section in which the non-effective magnetic flux range portion (W) positioned in the orthogonal direction is cut evenly at both ends. The material composition is also a Nd—Fe—B or Sm—Co rare earth magnet, which corresponds to a reduction in the size of the diameter. As is clear from FIG. 2B, the magnet 2 itself has a symmetric cross-sectional shape with respect to the rotation center axis 6 as described above, and the rotor balance is dynamically maintained.

  Similarly, the rotor unbalance means is the same as that shown in FIG. Here, the only difference from FIG. 1 is that the magnet 2 and the eccentric weight 3 are integrally joined to the rotating shaft 6 by the resin mold 20. This is a structure designed to reduce the process and improve the mass productivity in the assembly manufacturing process. By adopting the resin mold 20, simply setting each part in the molding die, the series of operations from the positioning of the dimensions to the fixing of the joining mold is simplified, and the cost in the rotor assembly process can be reduced. It also leads to an increase in impact resistance of the entire rotor.

  In addition, the rotational axis is arranged at the center of gravity of the rotor magnet 2 itself, and the eccentric weight 3 which is a weight inertial body is entirely coated with a resin mold on the outer peripheral surface of the magnet 2 to be integrated, The entire rotor portion can be assembled without applying mechanical stress to the extremely small-diameter rotating shaft 6. Also, as a rotor part, mounting by integrating the magnet 2 and the eccentric weight 3 to the shaft that is the rotating shaft 6 is achieved by reducing the productivity and cost by the resin molding method using injection molding technology. Accuracy is also improved. The rare earth magnet material can be integrally molded with a resin magnet in addition to a sintered magnet. For example, as shown in FIGS. 4 (a) and (b), The resin magnets 32 and 34 are combined to increase the degree of design freedom.

  As described above, according to the present embodiment described above, a rotor structure that rotates while maintaining the magnetic balance of the rotor magnet at all times and effectively using the magnetic flux between the field coils can be realized, and the vibration force can be reduced. In order to obtain the vibration motor, it is possible to obtain an effective vibration motor in which an eccentric weight which is a heavy inertia body having a high specific gravity is disposed at an eccentric position of the rotor. Furthermore, as a motor, an inner rotor type vibration motor that can be further reduced in diameter and size without reducing rotational efficiency can be provided.

  Mainly mobile communication devices such as multi-function mobile phones such as mobile phones that require vibration functions, wristwatch-type PHS, on-site small wireless communication devices, and various information communication terminal devices such as portable PDAs , And game machine controllers with body vibration, and electronic devices including electronic toys such as pocket game machines.

2A and 2B are a schematic cross-sectional view taken along line AA and a schematic cross-sectional view taken along line BB showing the internal structure of the inner rotor type vibration motor according to the present invention. 2A and 2B are a schematic cross-sectional view taken along line AA and a schematic cross-sectional view taken along line BB showing the internal structure of the inner rotor type vibration motor according to the present invention. The explanatory schematic diagram showing the magnet effective magnetic flux range (R) and ineffective magnetic flux range (W) of the inner rotor part concerning the present invention. Sectional reference drawing which shows the deformation | transformation combination example of the magnet of the inner rotor part which concerns on this invention, and an eccentric weight shape. Sectional reference drawing which shows the structural example of the conventional vibration motor which attached the eccentric weight to the output-shaft front-end | tip.

Explanation of symbols

1, 100 vibration motor
2, 22, 32, 34, 102 Magnet
3, 33, 35, 103 Eccentric weight
4, 24, 104 Field coil
5, 25, 105 Housing case
6, 106 axis of rotation
7, 107 End flange
8, 108 Bearing
9 Thrust receiving
10, 110 liner
11, 111 terminal
12, 112 Power supply terminal
20 Resin mold R Magnet effective flux range W Magnet ineffective flux range

Claims (4)

A field coil for generating an electric magnetic field is arranged on the inner wall of the housing case of the cylindrical motor, and the stator side bearings are arranged at both ends of the cylindrical housing case. In the inner rotor type cylindrical motor
The magnet shape of the rotor portion supported by the rotating shaft is a plate-shaped magnet having a substantially rectangular cross section in which both ends of the ineffective magnetic flux range portion positioned in a direction orthogonal to the magnetic pole direction of the radially anisotropic magnet are cut out equally. And the rotor is balanced with respect to the rotation center axis.
On the other hand, as an unbalanced weight of the rotor part, a weight inertial body made of a non-magnetic material that fills one side of the evenly cut space of the magnet is separately provided as an eccentric weight and eccentric to the rotor part. Inner rotor type vibration motor.   2. The inner rotor type vibration motor according to claim 1, wherein the vibration motor is driven by a two-phase or three-phase DC brushless drive system.   The combination of the magnet constituting the rotor part and the weight inertial body is a rare earth magnet made of an Nd magnet or Sm magnet and an eccentric weight made of a tungsten alloy having a specific gravity of 12 or more of a nonmagnetic material. The inner rotor type vibration motor according to claim 1 or 2.   A rotating shaft is arranged at the center of gravity of the rotor magnet, and an eccentric weight, which is a heavy inertial body, is fixedly attached to the magnet side by being directly bonded to the outer peripheral surface of the magnet or covered entirely with a resin mold. The inner rotor type vibration motor according to claim 1, wherein the inner rotor type vibration motor is provided.

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