JPH0744815B2 - Holding structure for position detecting element in brushless motor - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless motor, and more particularly to a holding structure for a position detecting element for detecting the position of a rotor.

[Background of the Invention]

2. Description of the Related Art Conventionally, as a rotor position detecting element holding structure in a brushless motor, for example, one described in Japanese Utility Model Publication No. 59-26785 is known. In this conventional example, a holder fixed to the stator side is provided with a recess and a stopper piece, and the position detecting element is fixed at a predetermined position of the holder by the recess and the stopper piece. It has the advantage that the mounting position in the radial direction can be easily and accurately obtained.

However, since the position detecting element and the holder that holds it are accompanied by dimensional variations in manufacturing, depending on the dimensional variations, the position detecting element is held in the recess of the holder in a strongly press-fitted state, or conversely there is a gap. May be held in a loose state. In this way, if the position detection element is held in the holder with a strong press fit, problems such as deformation or damage of the position detection element or deterioration of mounting accuracy will occur, and the position detection element will be held in the holder in a loose state. If this happens, the position detecting element will fall off the holder, and in any case, it was unsuitable as a holding structure for the position detecting element.

[Object of the Invention]

The object of the present invention is to prevent excessive press-fitting and backlash due to dimensional variation of each part when fixing the rotor position detecting element in the brushless motor to the holder on the stator side, excluding the above-mentioned drawbacks of the prior art. However, another object of the present invention is to provide a holding structure for a position detection element that provides a set press fit state.

[Outline of Invention]

In order to achieve this object, according to the present invention, a holder is provided with an insertion hole that is partially open, and an elastic piece is provided in the vicinity of the opening of the insertion hole, and a position detection element is inserted into the insertion hole. At this time, the front side of the position detecting element is elastically biased by the elastic piece so that the position detecting element is held in the insertion hole of the holder in an appropriate press-fit state.

Example of Invention

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a vertical sectional view of a brushless motor of the present invention applied to a rotary drum device of a VTR, FIG. 2 is an explanatory view of a position detecting element, FIG. 3 is an explanatory view of a holder, and FIG. FIG. 5 is an explanatory view showing a state in which the position detecting element of the figure is attached to the holder of FIG. 3, and FIG. 5 is a partially enlarged view of FIG.

In FIG. 1, reference numeral 1 is a rotary drum on which a video head 2 is mounted. The rotary drum 1 is fixed to an upper part of a rotary shaft 3 via a rotary support 4 and is rotatable around the rotary shaft 3. A fixed drum 5 is arranged below the rotary drum 1, and the fixed drum 5 is attached to the rotary shaft 3 via an upper bearing 6a and a lower bearing 6b. Reference numeral 7 is a laminated core, 8 is a coil around which a conductor is wound, and a stator 9 is constituted by the laminated core 7 and the coil 8. The stator 9 is fixed to the lower surface of the fixed drum 5 with a screw 11 via a boss 10. Has been done.

Reference numeral 12 is a case fixed to the lower part of the rotary shaft 3,
A ring-shaped motor magnet 13 and a frequency generator magnet (hereinafter abbreviated as FG magnet) 14 are fixedly attached to the inner peripheral wall of the motor magnet 13. Further, a tip portion of the motor magnet 13 is attached to the outer peripheral wall of the motor magnet 13. Signal magnet so as to protrude from 12 (hereinafter this is abbreviated as PG magnet)
15 are fixed to each other, and the rotor 16 is composed of these respective parts.

Reference numeral 17 denotes a printed circuit board, and a holder 19 and a holder 21 are provided on the lower surface of the printed circuit board 17, and one holder 19 is a position formed of a Hall effect element that faces the FG magnet 14 and detects the position of the rotor 16. The detection element 18 is held, and the other holder 21 faces the PG magnet 15 and faces the rotor.
A position detection element 20 composed of a Hall effect element that detects 16 positions is held. Further, 22 is a shield case made of a magnetic material, and the shield case 22 and the printed circuit board 17 are fixed to the lower surface of the fixed drum 5 together with the stator 9, and these shield case 22 and the printed circuit board
17 is insulated by an insulating plate 23.

In the rotary drum device having such a structure, in the brushless motor, the laminated core 7, the motor magnet 13 and the case 12 constitute a magnetic circuit, and the leads of the coil 8 are connected to a well-known electric circuit (not shown). When electric power is applied, torque is obtained and the rotor 16 rotates with respect to the stator 9.

The position detecting element 20 facing the PG magnet 15 has a second
As shown in the developed view in the figure, it is composed of a synthetic resin main body 24 and a plurality of leads 25 projecting from the lower end of the main body 24, and the main body 24 has a flat surface 24a on the front side and a flat surface on the rear side. 24b
It is formed to be narrower than the above, and an inclined surface 24c is formed between the flat surfaces 24a and 24b. The dimensions of each part of the main body 24 are such that the width of the front flat surface 24a is l ₁ and that of the rear flat surface 24b is
Is set to l ₂ , and the thickness from the bottom of the inclined surface 24c to the rear flat surface 24b is set to l ₃ .

On the other hand, the holder 21 holding the position detecting element 20
3 has an insertion hole 26 penetrating in the up-down direction as shown in a developed view of FIG. 3, and a pair of elastic pieces 21a having a narrow opening 26a on the front side of the insertion hole 26. Has been formed. Therefore, the portion surrounding the insertion hole 26 has a substantially C-shape, and both elastic pieces 21a formed at the tip end portion thereof are rich in elastic force. Incidentally, the width of the open portion 26a L _1, when the longitudinal width of the insertion hole 26 L _2, the transverse direction of the depth dimension of the insertion hole 26 and L _3, which are of the position detection element 20 It is set so that L ₃ > l ₃ l ₂ > L ₁ > l ₁ in relation to the size of each part.

Hold the position detecting element 20 dimensioned as described above in the holder 21.
When inserted into the insertion hole 26, the width L _{1 of the} opening 26a is larger than the width l ₁ of the front flat surface 24a of the main body 24 and smaller than the width l _{2 of the} rear flat surface 24b of the main body 24, as shown in FIG. , Both elastic pieces 21
The a can be brought into contact with both inclined surfaces 24c of the position detection element 20 with a pressing force.

At this time, as shown in FIG. 5, the accumulated value due to the dimensional variation of each component is represented by the amount of warp (or pressing force) of the elastic piece 21a of the holder 21, and this portion has the elastic force as described above. Since it has a structure having, it is possible to sufficiently absorb such dimensional variation.

In the above embodiment, the case where the number of the position detecting elements is 201 has been described. However, as in the case of the holder 19 for holding the position detecting element 18 facing the FG magnet 14, the holder 19 has two positions.
It goes without saying that the same effect can be obtained even if the above-mentioned cases are performed.

〔The invention's effect〕

As described above, according to the present invention, when the position detecting element of the rotor is held by the holder, the position detecting element is fixed in the insertion hole of the holder by the elastic force of the elastic piece formed in the holder. Variations in the dimensions of the detection element and the holder can be absorbed by the deformation of the elastic piece, and therefore the position detection element can be fixed to the holder without undue force being applied to each component.

[Brief description of drawings]

All the figures relate to the embodiment of the present invention. FIG. 1 is a vertical cross-sectional view when a brushless motor is applied to a rotary drum device of a VTR, and FIG. 2 is an explanatory view of a position detecting element. A plan view, the same figure (b) is a front view, the same figure (c) is a side view, FIG. 3 is an explanatory view of a holder, and the same figure (a) is a plan view.
4B is a front view, FIG. 4 is an explanatory view of a state in which a position detecting element is attached to a holder, FIG. 4A is a side view, FIG. 4B is a plan view, and FIG. The drawing is an enlarged view of the main part of FIG. 7 ... Laminated core, 8 ... Coil 9 ... Stator, 12 ... Case 13 ... Motor magnet 14 ... FG magnet, 15 ... PG magnet 16 ... Rotor, 17 ... Printed circuit board 18, 20 ... Position detection element, 19, 21 ... Holder 21a ... elastic piece, 24 ... main body 24a, 24b ... flat surface, 24c ... inclined surface 25 ... lead, 26 ... insertion hole 26a ... open part.

Claims (1)

[Claims] 1. A rotor having a magnet mounted on a case, a stator having a coil wound around a core, a position detecting element for detecting the position of the rotor, and a holder for holding the position detecting element on the stator side. In the brushless motor, the position detecting element has a flat surface on the front surface side, a flat surface on the rear surface side wider than the flat surface on the front surface side, and an inclined surface between the flat surfaces. A partially C-shaped insertion hole is provided to form a substantially C-shape, and the elastic piece at the tip of the substantially C-shape contacts the inclined surface of the position detection element, and the position detection element is inserted by the elastic force of the elastic piece. A structure for holding a position detecting element in a brushless motor, characterized in that it is fixed in a hole.