JPH0667156B2 - Method for manufacturing stator of brushless motor - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stator of a brushless electric motor used as a blower fan drive source for a home air conditioner or the like.

2. Description of the Related Art In recent years, it has become mainstream to control the capacity of compressors in air conditioners such as home air conditioners. In response to this, it is required to widely adjust the amount of air blown to the heat exchanger in multiple stages. Instead of the induction motor as the fan drive source that has been used to meet these demands, A method of operating a brushless motor, which is easy to adjust, with a DC power source is being adopted.

One of the major features of the brushless motor is that the winding configuration is much simpler than the induction motor that has been used in the past, but on the other hand, the current flowing through the winding becomes discontinuous due to the drive method. Therefore, electromagnetic vibration is generated. As one measure to reduce this point, it is adopted to integrally solidify the iron core and the winding with a thermosetting resin.

On the other hand, a rotor position sensor is used in the brushless motor,
Usually, they often adopt Hall elements.

A printed circuit board is often incorporated in a brushless motor for the purpose of connecting, fixing or winding the Hall element. Further, not only the position sensor but also the drive circuit component may be mounted on the printed circuit board and integrated into the stator by resin molding.

In these cases, considering the case where the printed circuit board is resin-molded without applying any fixing means to the stator core, the printed circuit board is greatly affected by the fluid pressure and temperature of the mold resin injected into the mold. Not only does it deform and cause accidents such as foil breakage and foil floating, but the position sensor mounted on the printed circuit board may also move with the printed circuit board, making regular rotation position detection impossible.

As a measure against the above-mentioned points, a method of projecting a part of the stator core insulation and inserting or hooking it in a hole provided in the printed circuit board is often adopted.

Problems to be Solved by the Invention Although the above countermeasures are improved as compared with the case where the printed circuit board is not fixed at all, they are not perfect yet and the following problems remain.

(1) Usually, thermoplastic resin is used for the stator core insulation, and the protrusions provided for fixing the printed circuit board are deformed by the heat and pressure during molding, especially when the resin pressure works upward. Does not serve the purpose of fixing the board.

(2) The location of the protrusion provided on the iron core insulation is limited in relation to the winding, and the location of the hole is also limited in relation to the component on which the printed circuit board is also mounted. Therefore, it can be fixed only at a place where both of them match, the number is smaller, and it is insufficient to receive the resin pressure.

Therefore, in the present invention, the following measures are taken in order to allow the printed circuit board to be more stably positioned in the mold during molding.

That is, a protrusion is provided on the upper end surface of the lower die mandrel, a protrusion protruding downward is provided on the inner surface of the upper die, the printed circuit board is sandwiched by both protrusions, and a bolt hole is formed that protrudes from the inner surface of the upper die and reaches the lower die. The pin for use has a stepped shape with a small diameter at the position of the upper end surface of the printed circuit board, and the resin injection gate provided in the mold is the center of the fixed core product thickness.

Function When the resin is molded with the above configuration, the fluid pressure of the resin is applied from the bottom to the top of the printed circuit board, and the printed circuit board receives the upward force, and the upper mold protrusion and the upper mold pin step. Movement and deformation are restricted by hitting the attachment part.

Embodiment An embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional view showing a molding state in a mold,
2 is a partial perspective view of the stepped pin, and FIG. 3 is a partial sectional view and a front view of a hole formed by the stepped pin.

In the figure, a stator winding completed product 2 is installed in a mandrel 1b provided in a cavity 1a of a lower mold 1, sealed by an upper mold 3, and a gate 4 is provided substantially at the center of the stator core in the stacking direction. The mold resin 5 is injected under pressure. The upper die 3 has a plurality of pins 6 and protrusions 7 protruding downward. The pin 6 secures a hole for inserting a fastening component 11 such as a bolt or a rivet when the molded stator 10 is assembled as a motor as shown in FIG. Further, the pin 6 has a stepped shape as shown in FIG. 2, and the outer peripheral projection 6a of the stepped component contacts the upper end surface of the printed circuit board 8 as shown in FIG. 8 is prevented from moving upward or bending and displacing. On the other hand, the portion formed by the outer peripheral chamfered portion 6b of the pin 6 has a function as a seat when fastening with a through bolt or a rivet. Further, the printed circuit board is clamped by the projection 7 and the projection 9 provided on the upper end 1c of the mandrel 1b of the lower mold 1, thereby positioning in the thrust direction and preventing movement by the molding resin.

The gate 4, which is the resin injection port, is provided in the central portion of the thickness of the stator core as described above. This means that the gate is located below the center of the thickness when viewed from the entire mold. This means that when the movement of the resin at the time of molding is estimated, the resin is first filled from the lower portion near the gate. This means that the resin force acts on the printed circuit board 4 from the lower side.
And the function of the protrusion 7 will be useful.

The stator winding finished product 2 is composed of a stator core, a winding formed on the stator core through an insulating layer, and a printed circuit board on which a driving circuit component and a position sensor are mounted. There is.

Effects of the Invention As described above, the following effects can be obtained by implementing the present invention.

(1) A stator of a brushless electric motor that molds a printed circuit board can be manufactured without quality problems such as bending of the printed circuit board and foil breakage.

(2) Since the printed circuit board is not bent or deformed, the position of the mounted position sensor can be accurately maintained.

(3) Since the printed circuit board is not bent or deformed, high quality production can be performed without stress such as deformation even when other electronic components are mounted.

(4) Since the pin for forming the hole for the through bolt has a different shape and simultaneously forms a seat at the time of fastening, there is no risk of the bracket or the like being dented or deformed by the fastening pressure during motor assembly.

[Brief description of drawings]

FIG. 1 is a sectional view showing a molded state of a stator according to an embodiment of the present invention, FIG. 2 is a partial perspective view of a stepped pin, and FIG.
Figures (a) and (b) are a front view and a sectional view of a hole formed by a stepped pin, and FIG. 4 is an exploded perspective view showing an assembled state of a brushless electric motor. 1 ... Lower mold, 2 ... Stator winding finished product, 3 ... Upper mold, 4 ... Gate, 5 ... Mold resin, 6 ... Pin,
7,9 ... Protrusion, 6a ... Pin outer peripheral protrusion, 6b ... Pin outer peripheral chamfer, 8 ... Printed circuit board.

Claims (2)

[Claims] 1. A stator core, a winding formed on the stator core via an insulating layer, a printed circuit board on which drive circuit components and a position sensor are mounted, and the wiring provided on the printed circuit board is used. In the stator manufacturing method of the brushless electric motor, the windings are connected to form a stator winding finished product, and the stator winding finished product is placed in a mold cavity and a molding resin is injected and solidified. A protrusion is provided on the upper end surface of the lower die mandrel that holds the finished stator winding, and a protrusion that protrudes downward on the inner surface of the upper die and a step that protrudes downward and reaches the bottom surface of the lower die cavity and has a small diameter below A pin having an attached shape is provided, and the finished stator winding product is mounted on a mandrel provided in a lower mold cavity, and both protrusions hold the printed circuit board from above and below when sealed by an upper mold. Dimensions and before A gate provided at a position corresponding to the central portion of the stack thickness of the stator core installed in the mold while the printed board is held with the dimension of the stepped portion of the pin abutting the upper end surface of the printed board. A method for manufacturing a stator of a brushless electric motor, in which a mold resin is injected and solidified. 2. The fixing of the brushless electric motor according to claim 1, wherein the stepped pin has a cross-section of a large-diameter portion having a triangular cross-section with a cross-section of the thin portion being an inscribed circle. Child manufacturing method.