JPS6387149A - Micro-motor case - Google Patents

Abstract

PURPOSE:To obtain the micro-motor case of simple mechanism excellent in magnetism and electromagnetic wave shield effect, by using the laminated plate of zinc-or-aluminum-plated lowest carbon steel sheets with thermal-fusion- weldable synthetic resin film between the sheets, for the motor case. CONSTITUTION:So far as a motor case 11 is concerned, the laminated plate of aluminum-plated lowest carbon steel sheets 12 with the thermal-fusion- weldable synthetic resin film 13 of denatured polyethylene system between the sheets 12 is pressformed in the shape of a bottomed cylinder. So far as a case cover 14 is concerned, the aluminum-plated lowest carbon steel sheets are press-formed. By the synthetic resin film 13, a magnetic hollow gap is formed, and magnetic flux loss is caused, and mechanical oscillation is effectively attenuated. In the meantime, by the case cover 14, leakage flux from the opening end of the motor case 11 is shielded, and by an aluminum-plated layer, electromagnetic wave is shielded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thin and lightweight micromotor case that has magnetic shielding effects, electromagnetic shielding effects, and distribution effects.

[Conventional technology]

Micro motors are used in audio products (tape recorders).

These products are often used in the drive parts of electrical products such as disk players, stereos, etc., but these products not only emit unnecessary radio waves from their electrical circuits themselves, but also emit magnetic and electromagnetic waves from attached devices. It is also considered a problem in product performance as a cause of noise.

In recent years, with the development of electronic equipment, the integration and integration of electrical circuits, etc.
As miniaturization accelerates, improvements in magnetic and electromagnetic shielding properties are required for the micro motors used in these products.
There is a growing demand for lighter and more compact products. Therefore, sufficient measures have been taken for the micromotor used in the above products, such as magnetic shielding by wrapping a silicon steel plate band around it, and shielding from both magnetic and electromagnetic waves by placing a shield case on top of it.

A conventional micro motor case will be described below with reference to the drawings.

Figure 7 shows the cross-sectional structure of a conventional micromotor, showing the entire cross section of the motor holder) and the magnetic shielding case 31, which is a silicon steel plate band wrapped around the body of the motor holder. shows.

In FIG. 7, (1) is a cylindrical motor case with a bottom, and an output shaft (9) is connected to an output side bearing (7) through an opening provided at the center of the bottom of the motor case (1). The stator magnet (2) is fitted on the inner circumferential surface of the
, a holding member for the brush (5) which is one of the constituent members of the contact, and a control board (6) are fitted in this order.

tfc, (1υ is a case lid, which has a recessed part in the center thereof into which the non-output side bearing (8) fits, and a flange part in the outer peripheral part which fits into the inner peripheral surface of the motor case (1). , is fitted into the motor case (1).

Further, the output shaft (9) has a non-output side bearing (8) whose non-output side end is fitted into a recess trap provided in the center of the case lid.
The output shaft (9) has a rotor magnet (3) at a position opposite to the stator magnet (2), and the other side of the contact at a position opposite to the brush (6). A commutator (4), which is a component of the above, is inserted.

The magnetic shielding case 131) is made by wrapping a silicon steel plate band □□□ around the body of the sweater βl) having the above structure, and forms a magnetic flux conductive circuit in the circumferential direction of the motor body using the silicon steel plate band having high magnetic permeability. However, it shields the magnetism from the stator magnet (2) and rotor magnet (8).

FIG. 8 shows a partial cross-sectional configuration of another conventional micromotor.

In FIG. 8, the motor (51) is the motor (4) shown in FIG. A magnetically shielded case with a bottomed cylindrical motor case and a case lid having an opening in the center into which the elastic member fitting fits, and a rim on the outer periphery to attach to the motor case fitting. for)
It is covered with.

This magnetic shielding case) forms a closed magnetic circuit around the entire circumference at the outermost layer by enclosing the motor shaft and the silicon steel plate strip □□□. 51) has a built-in stator magnet (2) and rotor magnet (8).
) and electromagnetic waves from contacts such as the commutator (4) and the brush (5).

In addition, it has the characteristics of both magnetic shielding characteristics and electromagnetic wave V-~D effect, and is used as a hole-groove member called
The carbon content in steel is known as α01.
% or less, and the grain size of the grain size is 14 or less in grain size number 1,000 + ÷ This is an aluminum plated steel sheet made by applying aluminum plating to a cold rolled sheet.

[Problem that the invention seeks to solve]

A micromotor has a built-in stator magnet and a rotor magnet. Magnetic leakage occurs from the magnetic field formed by these magnets, and furthermore, the current generated by the commutator and brushes built into the motor Since high-frequency electromagnetic waves are generated from the contacts, the micrometers used in the above-mentioned electrical products are required to have a sufficient shielding effect against both magnetic and electromagnetic waves.

However, although a magnetic material with high magnetic permeability and high magnetic shielding effect has an excellent effect in the low frequency region, it almost loses its effectiveness against electromagnetic waves in the high frequency region.

On the other hand, highly conductive materials with low specific resistance are highly effective in shielding electromagnetic waves in the high frequency region, but have little effect in magnetic shielding in the low frequency region.

In addition, since the most important feature of a micromotor is that it is lightweight and compact, the micromotor case that covers it must also be lightweight and compact, and it must also have enough strength as an outer skin component to hold the internal components. It is required to have rigidity. For this reason, micro motor cases are usually formed by deep drawing and deep bending a thin plate using a press, and the thin plate used has a good press that can withstand the deep drawing and deep bending. It is required to have moldable properties.

However, for example, a silicon steel plate having high magnetic permeability and excellent magnetic shielding effect has such poor formability that it requires softening treatment after wrapping.

In addition to these, microsators that require both magnetic and electromagnetic wave shielding effects are handled by using a plurality of structures that combine constituent members each having unique characteristics.

In the configuration shown in FIG. 7 described above, a silicon steel plate band (support) is wound around the body of the motor head (2) to form a magnetic circuit with high saturation magnetic flux in the circumferential direction of the body, and the stator magnet (2) and rotor magnet (8) (hereinafter both will be abbreviated as magnet).
However, since the motor case (1) and case lid d0, which are made of ordinary steel plates, have low magnetic permeability, the magnetic flux in the axial direction is The ordinary steel plate leaks from the commutator (4) and the brush (6).
) and other current contacts (hereinafter abbreviated as contacts) have drawbacks such as not being able to sufficiently shield electromagnetic waves on the high frequency side generated from them.

Moreover, since the silicon steel plate band mentioned above is simply wrapped around the outer periphery of the motor case (1), the motor case (1)
The disadvantage is that the adhesion is weak, and loosening that causes vibration and noise when the motor rotates is likely to occur.

The configuration shown in Fig. 8 consists of wrapping a silicon steel plate band (support) around the body of the motor holder shown in Fig. 7, and further layering the shield case holder to create a closed magnetic circuit that extends all around the outermost layer. In addition to shielding the above-mentioned high-wave magnetic flux, that is, magnetic flux leakage in the axial direction from the plane shown in (a) (→) in FIG. 7,
The double structure of the case doubles the surface reflection effect and completely shields electromagnetic waves from the contacts.

However, this configuration is due to its complex multiple structures, ■increases material and manufacturing costs, and hinders miniaturization and weight reduction.
(2) Due to its structure, there are many mechanical overlapping/fitting parts, and there are four drawbacks, such as loosening between the constituent members that can cause noise and noise when rotating from front to back.

Therefore, materials that can compensate for these drawbacks have been developed in the past, such as single-layer or Fi
Laminated thin plates were desired.

Note that the above-mentioned "Special Publication No. 61-2731" is known as a steel sheet that has both magnetic and electromagnetic shielding effects, but in order to provide magnetic shielding properties, the grain size of the steel sheet is designated by the grain size number S4. Since the coarse grains are as follows, when this steel plate is deep drawn in a press, it has the disadvantage that pear-like roughness occurs on the surface. As mentioned above, if such a steel plate is applied to a micro motor case that requires deep drawing and deep bending of a thin plate using a press, the roughness will not only reduce the product value but also make the plating layer uneven. Problems such as this arise.

SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a thin and lightweight micromotor case with a simple structure and excellent magnetic shielding effect and electromagnetic shielding effect.

[Means for solving problems]

The micro motor case according to the present invention to solve the above problems has a carbon content of α01% or less, and a grain size of J165 or more in grain size number, as shown in Fig. 1, which is a sectional view of the main part. 7 or less and a laminated plate in which a heat-adhesive synthetic resin film (2) is interposed between the steel plates (2), which are made of nine-pole low carbon steel and plated with zinc or aluminum, is pressed into a bottomed cylindrical shape. Molded motor case α℃,
The outermost layer of the opening of the motor case αD is capped with zinc or aluminum plating on the surface of ultra-low carbon steel with a carbon content of α01% or less and a grain size of grain size number 5 or more and 47 or less. It is constructed with a case lid 04 formed by press-forming a single-layer steel plate.

[For production]

In the present invention, the motor case αη has a synthetic resin film A3 interposed in the middle in order to fully utilize the characteristics of ultra-low carbon steel with high magnetic permeability and high magnetic shielding effect.
The synthetic resin film A3 interposed in the middle forms a magnetic hollow fault, and this hollow fault has the effect of causing magnetic flux loss. It has the effect of damping the vibration between the shaft and the bearing. On the other hand, the case lid α→ has the effect of preventing magnetic flux leakage from the open end of the motor case 011 by being attached to the outermost layer of the motor case 01). A magnetic closed circuit is completed on the entire outermost periphery (excluding the output shaft and input hole).

Figure 5 shows ultra-low carbon steel with a carbon content of α009%.
For nine plates rolled to a thickness of 5 mm, the r value of the grain size and steel sheet formability (a dimensionless value obtained by dividing the strain in the width direction of a tensile test specimen by the strain in the thickness direction; the higher the value, the higher the value. This is a graph showing the results of an investigation into the relationship between the plate's formability (high formability) and the presence or absence of roughness after small and deep drawing (inner diameter 33 mm, depth 3 Q mm) leakage magnetic flux. be.

This graph shows that the larger the grain size of an ultra-low carbon steel sheet, the better its magnetic shielding properties and workability. It will be appreciated that because of this occurrence, this region is difficult to apply to products requiring deep drawing. On the other hand, in a fine grain region where the grain size number exceeds 7, the r value tends to decrease, making deep drawing difficult.

Considering these characteristics, the grain size of the steel sheet is determined by the grain size number 1.
5 or more and S7 or less.

Figure 6 shows the carbon content of a carbon steel sheet rolled to a thickness of α5 mm and whose grain size is varied by grain size number. This is a graph showing the results of investigating the relationship between size and size 9g. The magnetic shielding effect of ultra-low carbon steel sheets tends to increase when the carbon content is less than α01% even in fine grains with grain size numbers JI & 6. As a result, the carbon content of the steel plate was set to 101% or less.

Furthermore, the plating layer applied to the steel plate has the effect of shielding electromagnetic waves of approximately 600 KHz or more generated from the contacts due to its good electrical conductivity and skin effect, and also has the effect of preventing rust on the steel plate. In addition, there are other highly conductive materials such as copper, but zinc or Aluminum plated.

〔Example〕

Examples of the micro motor case according to the present invention are shown below, and FIG. 2 shows a full sectional view of the first example.

In Figure 2, αη is carbon content 1009%,
Press-molding a laminate with a modified polyethylene heat-sealable synthetic resin film (2) interposed between ultra-low carbon steel plates (2) with a grain size number of 46 and aluminum plated on the surface. The output shaft (9) is fitted into an opening provided at the center of the bottom of the motor case αp through an output side bearing (7). Further, a stator magnet (2), a holding member for a brush (6) which is one of the constituent members of the contact, and a control board (6) are fitted in this order into the inner peripheral surface thereof.

Mano, (b) is a case lid made by press-forming an ultra-low carbon steel plate with a carbon content of 0.009%, a grain size of uneven grain size, and an aluminum plated surface. A recess into which the non-output side bearing (8) fits is provided in the center, and a rim which fits into the outermost surface of the motor case I is provided on the outer periphery, and the motor case α11) K is mounted.

Furthermore, one output shaft (9) has the y output side end connected to the case α
◆It is installed in the nine concave part in the center of the nine output side bearing (
8) The output shaft has a rotor magnet (2) at a position opposite to the stator magnet (2).
8), a commutator (4), which is the other component of the contact, is inserted at a position opposite to the brush (6)K.

The above structure (carbon content is 1009%, crystal grain size is grain size/IE6, aluminum plating is applied to the surface, and a heat-fusible synthetic resin film of modified polyethylene is placed between ultra-low carbon steel plates) As an example of a motor case (made by press-forming a laminated plate with a
mm Tojinen laminate ■ (thickness of steel plate - α425ynm,
The intervening synthetic resin film thickness αQ5mm, the steel plate thickness α425tnm) were press-formed. 6) and a comparative motor case ■ made by press-forming an aluminum-plated steel plate with a plate thickness of α9mm, the same magnetism was applied from the inner surface of each motor case, and the magnetic shielding effect (the magnitude of leakage magnetic flux) was evaluated. As a result of comparing 3), the magnitude of the leakage magnetic flux was 5.5% for the former [with] and 7.9% for the latter (2). In other words, the ft4=-ta case made by press-molding the laminated plate (■) is an example of a case used as a motor case in the present invention, but as is clear from the above comparison, the magnetic y-A/de effect is It has been confirmed that it is extremely superior.

4 shows an example of how the case cover is attached to the motor case shown in FIG. 2.

Figure 4-a shows the motor case (
2) and the case lid.The one shown here is made by press forming an aluminum plated ultra-low carbon steel plate (C% 閤α009, grain size s-s) with a thickness of α9mm. The case lid is attached to the outermost layer of the motor case.

The one shown in Figure 4-S is fitted into the inner surface of the case lid (the 6th one is the motor case Ql) and is installed in nine different ways. It is made by press-molding a plate.

The case shown in Fig. 4-G is a case lid (7) attached to the outermost layer of the motor case αη. F
] is press-molded.

Regarding the installation examples of the motor case and case lid shown in Figure 4-a, Figure 4-b, and Figure 4-〇 above, the same magnetism is applied from the inner surface of the motor case, and the respective joints are As a result of measuring the magnitude of the leakage magnetic flux from the vicinity of the part, the ratio of the one in FIG. - The one in Figure 4 is L25), and the one in Figure 4 is L.
It was lo.

The above results are shown in Fig. 4 - Example of mounting the motor case α.
A magnetic closed circuit cannot be formed with respect to the outermost layer of .eta., and the magnetic flux from the outermost layer leaks from the end (c) shown in FIG. 4. In addition, in the installation example shown in Figure 4-0, although a magnetic closed circuit is formed for the outermost layer of the motor case αη, due to the magnetic fault effect of the synthetic resin film interposed on the case lid ff4). shi, practically α425
Even if a case lid with a thickness of 1.0 mm is used, the magnetic flux exceeding the saturation magnetic flux at this thickness will leak from the part shown in Figure 4--) and reach the outermost layer of the case lid (74). introduced (e)
This results in leakage from the ends.

Based on these results], the mounting structure of the case lid to the motor case is that of the mounting structure adopted in the present invention, in which the case lid of a press-molded single-layer plate is attached to the outermost layer of the motor case. It will be appreciated that it is most effective against V-y.

In addition, during implementation, the magnetic seam/L of the laminate and single layer
The thickness of the steel plate used for the case cover should be greater than the thickness of the laminated plate used for the motor case, taking into account the difference in the board effect. According to experiments, assuming that the latter plate thickness is 1.0, the optimum combination is that the latter plate thickness is in the range of 1.1 to 1.5.

Moreover, even if chromate treatment or phosphate treatment is applied to the zinc or aluminum plating applied to the ultra-low carbon steel sheet described above, the effect cannot be prevented.

In addition, as the synthetic resin film interposed on the above-mentioned plated ultra-low carbon steel plate, here we use a heat-fusible synthetic resin film that has good adhesion to the steel plate and has good press formability after lamination. An example in which a modified polyethylene-based synthetic resin film is used is shown below, but there are other heat-sealable synthetic resin films such as modified polypropylene, and their use cannot be prevented.

FIG. 3 shows a full sectional view of the second embodiment. It should be noted that since this embodiment is similar to the first embodiment shown in FIG. 2 in terms of basic structural members, explanations of some of the structural members will be omitted.

In Figure 3, ? υ is carbon-containing company α009%,
The crystal grain size is A6 with grain size number, the surface is aluminum plated, a modified polyethylene heat-sealable synthetic resin film (6) is interposed between the nine low carbon steel plates (6), and nine laminated plates are pressed. The non-output side bearing (
8) is a cylindrical motor case with a bottom and a recess into which the motor case is fitted.

In addition, the trowel has a carbon content of α09%, a grain size of I&6 in grain size numbers, and a case lid made of press-formed ultra-low carbon steel plate with aluminum plating on the surface,
an opening into which the output shaft side bearing (γ) is fitted;
The outer periphery is provided with a rim that fits onto the outermost surface of the motor case (11), and is attached to the motor case αp.

The micromotor case configured in this manner has the same magnetic shielding effect, electromagnetic shielding effect, and vibration damping effect as the first embodiment shown in FIG.

In addition, the motor case (c) and case lid (c) of this configuration
C) can also function as a magnetic/electromagnetic wave shielding case by encasing and sealingly attaching it to a commercially available micromotor. That is, for example, the magnetic shield case j31) of the micro motor shown in FIG. 7 shown as the prior art is removed, and the motor case shown in FIG.
By placing them in such a way that they are covered by the case cover (product) and the case lid (product), magnetic and electromagnetic wave V-μ wave effects equivalent to or greater than the conventional technology shown in Fig. 8 can be obtained, and the silicon steel plate strip (support material) This makes it possible to reduce the weight and reduce material and manufacturing costs.

〔Effect of the invention〕

As described above, the micromotor case of the present invention generates magnetic flux loss through the formation of magnetic faults by the heat-adhesive synthetic resin film interposed between the laminates, thereby making the ultra-low carbon steel plate magnetic. The effect of increasing the shielding effect and the stacking effect of plating layers with good conductivity properties has the effect of further increasing the stain magnetic wave seeding effect, and the case lid has a magnetic closed circuit around the entire circumference. By forming 71, it is possible to obtain the effect of preventing magnetic flux leakage.

9 carbon content (101
% or less, by adjusting its grain size to I65 or more and A7 or less in terms of grain size number, deep drawing)
It has improved characteristics and can be applied to micro motor cases that require thin walls and deep drawing.In addition, by interposing the resin film in the middle, the magnetic shielding effect is further enhanced. This also allows for thinner walls.

Therefore, the micro motor case according to the present invention eliminates the need for measures such as wrapping a silicon steel plate band around the motor body and layering a magnetic shield case on top of the silicon steel plate band, unlike conventional products, and makes it easy to manufacture micro motors. It is possible to reduce assembly man-hours and materials, and make it lighter and more compact. In addition, by reducing the number of overlapping and mating parts in the micromotor structure, not only can the causes of vibration and noise generated during motor rotation be reduced, but the motor case itself can have a damping effect. .

[Brief explanation of the drawing]

FIG. 1 is a main sectional view of the micro sweater case of the present invention. , FIG. 2 is a full sectional view of the micromotor case of the first embodiment. FIG. 3 is a full sectional view of the micromotor case of the second embodiment. Fig. 4-a, Fig. 4-su, Fig. 4-CFi, partial sectional views showing examples of attachment of the motor case and the case lid. FIG. 5 is a graph showing the relationship between grain size, leakage magnetic flux, and deep drawing formability. FIG. 6 is a graph showing the relationship between carbon content and leakage magnetic flux. FIG. 7 is a full sectional view of a conventional micromotor. FIG. 8 is a partial sectional view of another conventional micromotor. 11 is the motor case. 12 is a plated ultra-low carbon steel plate. 13 is a heat-fusible synthetic resin film. 14 is the case lid. 21 is the motor case. 24 is the case lid.

Claims (1)

[Claims] In a micro motor case consisting of a bottomed cylindrical motor case (11) and a case lid (14) attached to the opening of the motor case, the carbon content is set to 0.01% or less. Steel plate (1
A motor case (11) is made by press-molding a laminated plate with a heat-fusible synthetic resin film (13) interposed between 2) and 2).
) and an ultra-low carbon steel which is attached to the outermost layer of the opening of the motor case (11), has a carbon content of 0.01% or less, and has a grain size of No. 5 or more and No. 7 or less in grain size number. and a case lid (14) formed by press-forming a single-layer steel plate whose surface is plated with zinc or aluminum.