JP2002078303A - Moving-magnet electric motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a moving-magnet electric motor, in which it damages can be controlled on rotary shaft, while minimizing its cost. SOLUTION: This motor is provided with a rotor magnet 4, having a through- hole 41 at its center, the rotary shaft 5 which is inserted and fixed in the through-hole 41 of this rotor magnet 4, bearing members comprising a housing 1 that supports this rotary shaft 5 and stores the rotor magnets 4, and coils 2, 3 that cause torque on the rotor magnet 4. On the surface of the rotating shaft 5, a vapor deposed coating 51 of TiN metal compound is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a movable magnet type electric motor using a rotor magnet made of a permanent magnet as a rotor, for example, a movable magnet mounted on a combination meter for a vehicle and suitable as an actuator for an instrument for swinging a pointer by a swing angle. Type electric motor.

[0002]

2. Description of the Related Art As an instrument actuator, for example, a coil-type electric motor in which a rotor magnet having a fixed rotating shaft is provided in a pair of coils arranged in a crossed or opposed manner, or a rotor magnet provided with a rotating shaft is made up of a coil and a yoke There is known a stepping motor type electric motor which is disposed in the hollow of an annular stator core consisting of: The rotor magnet used in this type of movable magnet type electric motor has a through hole at its center, and the rotating shaft is inserted (press-fitted) into this through hole such that both ends of the rotating shaft penetrate therethrough. The rotor magnet is assembled and fixed in a penetrating state.

As the pointer shaft, for example, SUS (stainless steel) type or iron type metal material plated with Ni (nickel) is used in many cases, and rotor magnets have recently been used, for example, Fe-B. -Nd (iron-boron-
Synthetic resin magnets obtained by combining Fe-Nd-based magnetic powders of neodymium) with a synthetic resin binder tend to be used for reasons such as superior performance.

[0004]

However, when a rotary shaft made of SUS or an iron-based material and Ni-plated is inserted into a through-hole of the rotor magnet made of the synthetic resin magnet and assembled, the surface of the rotary shaft has the above-mentioned problem. The surface of the rotating shaft is scratched by rubbing against the powder contained in the synthetic resin magnet, and the scratch increases friction with the bearing member that supports the rotating shaft, thereby increasing mechanical hysteresis and moving the movable magnet. When the type motor is used as an instrument actuator, there arises a problem that a pointing error increases.

In order to avoid this, a method of insert-molding (integrally molding) the rotating shaft with the rotor magnet or, as shown in, for example, Japanese Utility Model Application Laid-open No. Hei 3-60075, the diameter of the portion holding the rotor magnet is changed. It is conceivable to adopt a structure in which both ends supported by the bearing member are formed into small diameters so that the small diameter portions of the rotating shaft do not rub against the rotor magnet when the rotating shaft is inserted. However, there is a problem in that the cost increases, and in the case of changing the outer diameter of the rotating shaft, there is a problem that cutting is required and the cost is increased.

The present invention has been made in view of the above points, and a main object of the present invention is to provide a movable magnet type electric motor capable of suppressing damage to a rotating shaft while suppressing costs.

[0007]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a rotor magnet having a through hole at the center, a rotating shaft inserted and fixed in the through hole of the rotor magnet, and And a bearing member for supporting the rotating shaft, and a deposited film of a metal compound is provided on a surface of the rotating shaft.

The present invention is further characterized in that the vapor-deposited coating is applied to at least a surface region which is supported by the bearing member.

Further, the present invention is characterized in that the deposited film is made of a Ti-based metal compound.

Further, according to the present invention, the rotor magnet is made of Fe-N
It is made of a synthetic resin magnet containing d-based or Fe-Pr-based magnetic powder.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A movable magnet type electric motor according to the present invention has a rotor magnet having a through hole at the center, a rotating shaft inserted and fixed in the through hole of the rotor magnet, a rotor for supporting the rotating shaft and a rotor. A bearing member including a housing for housing the magnet is provided, and a coil for applying a rotational force to the rotor magnet is provided. The surface of the rotating shaft is covered with a metal compound vapor-deposited film. This protects the surface of the rotating shaft,
It is possible to prevent the surface of the rotating shaft from being damaged when the rotating shaft is fixed through the through hole of the rotor magnet. Moreover, as in the past, the rotary shaft is insert-molded into the rotor magnet,
The cost can be reduced as compared with the case where the outer diameter of the rotating shaft is changed.

For example, TiN (titanium nitride), TiC (titanium carbide), TiCN (titanium carbonitride), TiAlN (aluminum nitride-titanium), Zr
A metal compound such as N (zirconium nitride) or Cr-N (chromium nitride) is formed by vapor deposition on the surface of the rotating shaft by an arc ion plating method, and the magnetic powder contained in the rotor magnet is good but has high hardness. . Among the metal compounds, Ti-based (TiN, TiC, TiCN, TiAl
N) is preferred in terms of hardness and cost. Note that such an alloy coating film can be formed on the entire surface of the rotating shaft, or can be partially applied so as to include at least a surface region supported by the bearing member.

The rotor magnet is made of, for example, Sm-Co (samarium-cobalt) or Fe-Nd (iron-neodymium).
Any magnet can be used as long as it is a synthetic resin magnet formed by binding a magnetic powder of Fe-Pr (iron-praseodymium) type with a synthetic resin binder and capable of inserting and fixing a rotating shaft. Fe-Nd (iron-neodymium) which has particularly high hardness among magnetic powders
In the case of a Fe-Pr (iron-praseodymium) powder,
The use of a deposited film is effective.

The movable magnet type electric motor according to the present invention is not limited to a coil type electric motor or a stepping motor type electric motor, but can be applied to any type of movable magnet type electric motor using a permanent magnet as a rotor. It is suitable for a movable magnet type electric motor used as an instrument actuator.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a movable magnet type electric motor according to the present invention will be described below with reference to the accompanying drawings.

FIGS. 1 and 2 show a first embodiment of the present invention. FIG. 1 is a sectional view of a movable magnet type electric motor, and FIG. 2 is a sectional view of a main part of a rotary shaft of FIG.

In FIG. 1, a movable magnet type electric motor according to this embodiment has a housing (bearing member) 1 made of synthetic resin.
And a pair of coils 2 and 3 wound around the outer periphery of the housing 1 and a rotor magnet 4 housed in the housing 1.
And a rotary shaft 5 that is fixed through the rotor magnet 4 and is supported by the housing 1.

The housing 1 is formed by combining a first frame 11 and a second frame 12, and has therein a hollow portion 13 for accommodating the rotor magnet 4, and a shaft at both ends of the rotating shaft 5. And a pair of bearing portions 14 and 15 for supporting.
The end side of the rotating shaft 5 that is supported by the projection protrudes outside from the housing 1 (the first frame 11).

The coils 2 and 3 are connected to the rotating shaft 5 of the housing 1.
It is wound in an intersection so that an intersection is formed near it,
The directions of the magnetic fields generated by energizing the coils 2 and 3 are set to be substantially orthogonal.

The rotor magnet 4 is made of, for example, Fe-B-Nd
Fe consisting of rapidly quenched fine pieces of (iron-boron-neodymium)
A synthetic resin magnet in which Nd-based magnetic powder is bonded with a synthetic resin binder such as polyamide or epoxy, and a through hole 41 extending in the axial direction of the rotating shaft 5 at a central portion where the rotating shaft 5 passes;
And has a substantially cylindrical shape. Further, in the case of the present example, the rotor magnet 4 is magnetized such that the north pole and the south pole are polarized in the radial direction.

The rotating shaft 5 has a straight shape made of, for example, a SUS-based material, and a vapor-deposited film 51 of a metal compound, for example, TiN (titanium nitride) is applied to the entire surface as shown in FIG. I have.

The deposited film 51 is formed by an arc ion plating method known as a kind of vacuum deposition (for example, JP-A-6-128730, JP-A-2000-34561).
On the surface of the rotating shaft 5 with a thickness of about 0.3 μm.

The Vickers hardness of the Fe-Nd magnetic powder is in the range of about 550 to 750 Hv (the Vickers hardness of the Sm-Co powder is in the range of about 500 to 550 Hv).
On the other hand, the Vickers hardness of the deposited film of the TiN metal compound is about 2000 Hv. We prevent being hurt.

In the case of the TiN metal compound vapor-deposited film 51, its thickness is preferably 0.3 μm or more, and if it is less than this, it is difficult to prevent the rotation shaft 5 from being damaged.

When forming a vapor-deposited film of a Ti-based metal compound by the arc ion plating method, for example, TiC (titanium carbide), TiCN (titanium carbonitride), TiAlN (aluminum nitride-titanium) is used in addition to TiN. At this time, the thickness of the deposited film is adjusted by rotating shaft 5
May be set to a film thickness that can protect.

When these non-Ti metal compounds are deposited by arc ion plating, for example, ZrN (zirconium nitride), Cr-
N (chromium nitride) is selectable.

Further, a deposited film 51 of a TiN metal compound
Has a small coefficient of friction, so that the friction with the bearings 14 and 15 can be reduced. This also contributes to the suppression of mechanical hysteresis, and also reduces the friction with the inner wall surface of the through hole 41 during the operation of penetrating the rotating shaft 5. Therefore, the assemblability can be improved.

As described above, in this embodiment, the rotor magnet 4 having the through hole 41 at the center, the rotating shaft 5 inserted and fixed in the through hole 41 of the rotor magnet 4, and the rotating shaft 5 are supported. A bearing member comprising the housing 1 accommodating the rotor magnet 4 and coils 2 and 3 for applying a rotational force to the rotor magnet 5 are provided, and a deposition film 51 of a TiN metal compound is applied to the surface of the rotating shaft 5. Accordingly, the surface of the rotating shaft 5 can be protected, and the rotating shaft 5 is connected to the through hole 41 of the rotor magnet 4.
The surface of the rotating shaft 5 can be prevented from being scratched when it is fixed through. In addition, the cost can be reduced as compared with the conventional one in which the rotary shaft is insert-molded into the rotor magnet or the rotary shaft is machined to change the outer diameter.

In this embodiment, the coils are wound around the housing 1 so that the coils 2 and 3 intersect. However, the coils of the housing 1 are opposed to the rotor magnet 4 in a state where the coils 2 and 3 do not intersect.
It can be wound around the housing 1, or can be separately arranged outside the housing 1 without being wound around the housing 1.

FIG. 3 is a sectional view showing a second embodiment of the present invention in which the movable magnet type electric motor according to the present invention is applied to a stepping motor type electric motor.

That is, in this example, the coils 21 and 31 wound around the pair of coil bobbins 6 and the coils 21 and 31
The two annular stator cores 8 formed by combining a plurality of yokes 7 for guiding the magnetic path are laminated in the axial direction of the rotating shaft 5, and are rotated in the hollow of the laminated body of the stator cores 8 in the same manner as in the first embodiment. The rotor magnet 4 having the shaft 5 fixed therethrough is accommodated therein, and the rotating shaft 5 is supported by a bearing plate (bearing member) 9 which is mounted and fixed so as to sandwich the laminated body of the stator core 8. The rotor magnet 4 has a plurality of N-poles and S-poles alternately magnetized, and a bearing 9 a made of a separate component is provided at each of nine bearing plates corresponding to the rotating shaft 5.
Are fixed, and the rotating shaft 5 is supported by the bearing 9a. In addition, the point of providing the deposited film 51 on the surface of the rotating shaft 5 is as follows.
This is the same as the first embodiment.

According to the second embodiment, the same effect as that of the first embodiment can be obtained.

[0033]

As described in detail above, according to the present invention,
A rotor magnet having a through hole in the center, a rotating shaft penetrating and fixed to the through hole of the rotor magnet, and a bearing member that supports the rotating shaft, and a metal compound vapor-deposited film is formed on the surface of the rotating shaft. With this arrangement, it is possible to provide a movable magnet type electric motor capable of suppressing damage to the rotating shaft while suppressing costs.

[Brief description of the drawings]

FIG. 1 is a sectional view of a movable magnet type electric motor according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a rotary shaft in the embodiment.

FIG. 3 is a sectional view of a movable magnet type electric motor according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Housing (bearing member) 2, 3, 21, 31 Coil 4 Rotor magnet 5 Rotating shaft 6 Pointer shaft 6 Coil bobbin 7 Yoke 8 Stator core 9 Bearing plate (bearing member) 9a Bearing 51 Deposition coating

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H002 AA08 AB08 AC06 AE02 5H615 AA01 BB01 BB15 PP02 PP24 SS03 SS38 TT05 5H621 GA02 GA07 GA16 GB09 GB14 JK04 JK14 JK15 JK17 JK19 5H622 CA01 CA07 DD02 PP01 PP11 QA03

Claims (4)

[Claims] 1. A rotor magnet having a through hole in the center, a rotating shaft inserted and fixed in the through hole of the rotor magnet, and a bearing member for supporting the rotating shaft. A movable magnet type electric motor comprising a vapor-deposited film of a compound. 2. The movable magnet type electric motor according to claim 1, wherein said vapor-deposited coating is applied to at least a surface region supported by said bearing member. 3. The movable magnet type electric motor according to claim 1, wherein the deposited film is made of a Ti-based metal compound. 4. The method according to claim 1, wherein the rotor magnet is made of Fe—Nd or F
The movable magnet type electric motor according to claim 1, comprising a synthetic resin magnet containing e-Pr-based magnetic powder.