JPS6046759A - Plane facing type brushless dc motor - Google Patents

Abstract

PURPOSE:To improve the rotating efficiency by forming a recess on a stator core portion corresponding to a rotary force nongenerating portion in a stator coil. CONSTITUTION:Since recesses 9a, 9b,..., 9f at the back sides of stator coils 10- 15 are air gaps, magnetic resistances are larger than the other portions. Thus, magnetic fluxes from rotor magnet near the holes of the recesses 9a, 9b,..., 9f are displaced to both sides of the recesses, i.e., the rotary force generating portions of the coils 10-15, thereby reducing the magnetic flux density of the recess portions. Therefore, the moving forces generated in the rotating direction by the coils 10-15 are further increased, and the radial moving force which is not acted as the rotary force is reduced. The both phenomena act to increase the rotating efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a surface-facing brushless DC motor used as a DD motor of a VTR or the like.

The conventional surface-facing brushless DC motor has been replaced with a DD motor (direct-coupled motor) for the rotating head cylinder in a VTR.
This will be explained by taking an example of a device that is used as a device and using FIGS. 1 to 5. To explain from the rotating head cylinder side, the reference numeral (1) in the figure is a lower cylinder, and (2) a lower cylinder, and the lower cylinder (1) is fixed to the VTR body side (not shown) via appropriate members. . A main shaft (4) is rotatably supported on the lower cylinder (1) via a bearing (3a> (3b).The upper cylinder (2) is fixed to this main shaft (4), and the upper cylinder is rotatable. (5a) (sb)
is a video head, and (6) is a rotary transformer. The diameter of the cylinder (1) (21) is about 60 mm or more in home VTRs, etc., but the diameter of the cylinder (1) (21) is about 60 mm or more, but the diameter of
The diameter of a small cylinder such as a MIJ VTR is about 40rrrmφ, and the entire rotating head cylinder is becoming smaller and lighter.

Below the rotating head cylinder, there is a main shaft (4) with a face-to-face brushless DC motor M for rotational drive.
is directly connected to. Both face-to-face brushless DC motors M have disk-shaped stator assemblies M! and a rotor assembly M2, both of which M,
M2 are arranged opposite to each other. In this facing arrangement, the stator assembly M! is fixed to the lower cylinder (1) via a stator mounting plate (7), while the rotor assembly 9M2 is fixed to the main shaft (4) via a bearing strike and a damper (8).

FIGS. 3 and 4 show the configurations of opposing surfaces in each of the assemblies I) M and M2, and six stator coils a[~aω are located on the opposing surface of the stator core (9) in the stator assembly M1. They are arranged consecutively at equal intervals in the rotation direction. On the other hand, in the rotor assembly M2, alternating NS magnetic pole rows constituting the rotor magnet ae* are arranged in an annular manner on a magnet mounting plate (17). The illustrated magnetic pole array is composed of eight poles. In Fig. 1, the symbol aυ is the FG coil, α1 is the PG magnet, (to) is the printed board, and on this printed board, there is a Hall element H1 for detecting the magnetic pole position of the rotor magnet (lI) as it rotates.
~H3 are arranged at angular intervals of 30° with respect to the main@(4).

Incidentally, the rotational force of the rotor assembly M2 is generated by the magnetic field generated by the rotor magnet αe and each stator coil (I).
The interaction between the current flowing through ae, that is, according to Lemming's left-hand rule, is generated in each stator coil (IG-(15). There are parts that generate forces that do not act effectively as forces. In other words, as shown in FIG. ...(15b
), the kinetic force according to the above law occurs in the radial direction and does not act as a rotational force. Therefore, it is desirable that the kinetic force directed in the radial direction be as small as possible when considering rotational efficiency and the like.

Further, as a motor for the above-mentioned small VTR, it is desired that the motor itself be small and lightweight.

The present invention has been made in view of such conventional demands, and aims to solve the above-mentioned demands by recessing the stator core portion corresponding to the non-rotational force generating portion of the stator coil. .

The present invention will be explained below based on the drawings. Figures 6 to 8
The figure shows an embodiment of the invention.

In these figures, members or parts that are the same as or equivalent to those in FIGS. 1 to 5 are designated by the same reference numerals, and redundant explanation will be omitted.

First, to explain the configuration, in this invention, the fifth
As shown in the figure, in each stator coil 00 to 09, a portion Qob that generates a force that does not effectively act as a rotational force)
(ttb)...(15b), that is, four parts (9a) are attached to the part of the stator core (9) corresponding to the part where rotational force does not occur.
(9b)...(9f) are drilled. Part 4 (9a
) (9b)...(9f), in the example shown in the figure, the plane area is the part where no rotational force occurs Qob)(llb)...(15b
), and its depth still extends to a depth position that is more than % of the thickness of the stator core (9). Note that the shape of these four parts (9a), (9b), ... (9f) is not limited to the illustrated example above, and can be made into any suitable shape. It can also be applied to the bottom of the

With such a depth mode, the stator core (9) is
Although it is divided by the rotational force non-generating portion Qob) Qlb)...Q5b), there is no problem in terms of operation.

In the embodiment shown in the figure, there is also a recess (9g) (9) in the stator core (9) other than the part where each stator coil αI
b)...(gt) is drilled.

The stator core (9) is usually produced by powder compression (iron-based sintered body) using a mold, so the recesses (9a) (9b
)...(9f), (9g) (9h)...(9) can be formed at the same time during this molding.

Recesses (in the example shown, recesses of (9L), (9a), and (9g))
As shown in FIG. 8, a Hall element 11. -H3 can also be stored.

Next, the effect will be explained.

Each stator coil Ql ~ (1! 19 recess on the back side (9
a) Since the portions (9b)...(9f) are voids, the magnetic resistance of these portions is greater than that of other portions.

Therefore, the magnetic flux from the rotor magnet frame in the vicinity of the perforated portions of each recess (9a), (9b), ... (9f) is transmitted to both sides of each recess (9a), (9b), ... (c+f), that is, to each stator. Coil aI ~ (rotational force generating portion in 15 (
10a) (lla)...(15a), and the magnetic flux density in the concave portions (9a) (9b)...(9f) decreases. Therefore, the kinetic force generated in the rotational direction by each of the stator coils a0 to (1!9) becomes larger, and the kinetic force in the radial direction that does not act as a rotational force decreases.

Both phenomena act to increase rotational efficiency.

However, due to an error in the winding shape of the stator coil, the stator coil may tend to generate a motion force in the rotational direction even in a portion where no rotational force is generated. However, in this portion where no rotational force occurs, the magnetic flux density is reduced as described above, so the rotational force caused by such a winding shape error is suppressed to a minimum. Therefore all stator coils (
Even if the above-mentioned winding shape error occurs in some of the coils in the problems II to a, the tendency for the rotational force to become unstable due to this error is eliminated.

Furthermore, each recess (9a
) (9b) ・C9t), (9g) (9h) ・・
- (9t) contributes to making the DC motor M Iil.

Furthermore, these recesses (9a) (9b)...(9f)
s (9g) (9h)... (When using any of the nine and storing the Hall elements H, ~H3,
The entire DC motor M can be downsized. In addition, the four parts (9g) (9h)...(9A) are used as the reference four parts of the appropriate positioning jig when installing each stator coil (1(!-(151) to the stator core (9). You can also do it.

In the above-mentioned embodiment, a case was described in which the face-to-face type pushless DC motor according to the present invention was applied as a DD motor of a VTR, but the DC motor according to the present invention is not limited to such applications, and can also be used in Φ Yapstan, etc. It can also be applied as a motor in other equipment.

As detailed above, according to the present invention, since the stator core portion corresponding to the portion where no rotational force is generated in the stator coil is provided with four parts, the kinetic force generated in the stator coil is absorbed in the radial direction that does not contribute to the rotational force. Since the force can be reduced and the force in the rotational direction is increased, the rotational efficiency can be improved. Further, even if there is a winding shape error in a portion where no rotational force occurs in each stator coil, instability in rotation caused by this can be eliminated. Furthermore, the weight of the entire motor can be reduced, making it suitable for incorporation into small equipment such as a small VTR. Furthermore, various effects such as being able to be used as a Hall element storage recess and making the entire motor smaller can be obtained.

[Brief explanation of drawings]

Figure 1 is a half-sectional side view showing a VTR rotating head cylinder to which a conventional surface-facing brushless DC motor is applied;
The figure is a bottom view of the VTR rotary head cylinder same as above, FIG. 3 is a plan view of the opposing part of the stator assembly in the face-to-face brushless DC motor of FIG. 1, and FIG. 4 is a plan view of the opposing part of the rotor assembly in the same DC motor. , 5th
The figure is a plan view illustrating the non-rotational force generating portion of each stator coil in the stator assembly in Figure 3;
8 to 8 show an embodiment of a surface-facing brushless DC motor according to the present invention, in which FIG. 6 is a plan view of the facing portion of the stator assembly, FIG. 7 is a side view of the same stator assembly, and FIG. ◇ is a partially enlarged side view showing the case where the Hall element is housed in the four parts. 4: Main ll1I17: Stator mounting plate 9: Stator core 9a to 9t: Recessed portions 10 to 15 Nisteator coil 1ob-15b: Non-rotating portion 16: Roke magnet 17: Magnet mounting plate M: Surface facing brushless DC Motor MI: Stator assembly M2: Rotor assembly Clario 7 Co., Ltd. Agent Ashi 1) Naoe Figure 1 Figure 2 Figure 3 Figure 0 5 Figure 4

Claims (1)

[Claims] A rotor assembly and a stator assembly are disposed opposite to each other, and alternating NS magnetic pole arrays constituting a rotor magnet are disposed on the opposing surfaces of the rotor assembly in the rotational direction, and In a face-to-face DC motor in which a plurality of stator coils corresponding to the rotor magnets are arranged in series in the rotational direction on an opposing surface of the stator core, the stator core portion corresponds to a portion where no rotational force is generated in the stator coil. A surface-facing brushless DC motor characterized by having a recessed structure.