JPH10243602A - Small-sized motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized motor capable of preventing coming off of a washer from a rotary shaft when the motor is being assembled, and preventing or reducing the motor noise during operation of the motor. SOLUTION: In a small-sized motor 20 having a stator 22 mounted on the internal circumpherential surface of a casing 23 and a rotor 24 provided in its inside, a rotary shaft 25 of the rotor 24 is rotatably supported by two side bearing parts 26, 27 provided in the casing 23, a shock absorbing plate material 50 is provided, which is disposed between the rotor 24 and on slide bearing part 26 and insert mounted into the rotary shaft 25. In the shock absorbing plate material 50 having elasticity, a plurality of through holes having prescribed internal diameters larger than the external diameter of the rotary shaft 25 are made, and by bending the shock absorbing plate material 50 provided with restoring force, in a plurality of the through holes linearly arranged, the rotary shaft 25 is inserted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small motor,
In particular, electrical equipment for automobiles such as air conditioners for automobiles, VTRs
The present invention relates to small motors used in optical precision equipment such as audio / video equipment and small cameras.

[0002]

2. Description of the Related Art Small motors have been widely used in various fields in addition to the above devices, and there is a demand for prevention or reduction of motor noise and improvement of assembly workability in a manufacturing process.

FIG. 5 is a sectional view showing a part of a conventional small motor. As shown, in the small motor 1,
The stator 3 is mounted on the inner peripheral surface of the casing 2, the rotor 4 is disposed inside the casing 2, and the rotating shaft of the rotor 4 is fixed by one of the sliding bearings 5 and the other sliding bearing mounted on the casing 2. 7 is rotatably supported.

[0004] The motor 1 using the sliding bearing 5 requires a gap between the sliding bearing 5 and the rotor 4 due to its nature, and the support member 8 mounted on the rotor 4 is attached to the sliding bearing 5. In order to prevent direct contact, a flat annular washer 9
Are attached to the rotating shaft 7. The washer 9 is interposed between the support member 8 and the slide bearing 5 to reduce the sliding resistance between the slide bearing 5 and the support member 8 when a load in the thrust direction is applied to the rotor 4. .

[0005] A slight gap 11 is provided between the washer 9 and the slide bearing 5 so that the rotor 4 has play in the thrust direction. That is, when the entire rotor 4 undergoes thermal expansion due to a temperature rise accompanying the rotation of the motor 1,
If there is no play in the rotor 4, the washer 9 is sandwiched between the sliding bearing 5 and the support member 8 in a state of being strongly pressed, so that the friction loss increases the bearing loss and increases the current value. May stop and damage the motor. To prevent this, the rotor 4 has play in the thrust direction. Since the play amount of the rotor 4 is an important dimension for the function of the motor, when assembling the motor, the number of washers 9 or the thickness of the washer 9 is finely adjusted to a predetermined allowable size. ing.

[0006]

In the case of a motor in which the worm 10 constituting the speed reduction mechanism is mounted on the output side of the rotating shaft 7, a load in the thrust direction is applied to the rotor 4. For example, when the rotor 4 suddenly moves in the thrust direction and collides with the output-side slide bearing 5 at the start of rotation or at the time of a load change, a collision noise (so-called clicking noise) may be generated.
Further, when the rotor 4 vibrates in the thrust direction for some reason, the rotor 4 may repeatedly contact the slide bearing 5 to generate noise.

If a rubber-based material is used for the washer 9 in order to prevent or reduce the motor noise, frictional resistance at the time of sliding increases and torque loss occurs. When the washer 9 deteriorates due to wear, heat, or the like, the soundproofing effect gradually decreases. In particular, in the case of a thin motor,
Since the thickness of the washer 9 is also thin, the soundproof function cannot be sufficiently exhibited by absorbing the energy by elasticity only in the thickness direction (that is, the thrust direction of the rotor 4).

Further, in the case where irregularities are formed on the flat portion of the washer 9 (see Japanese Utility Model Laid-Open No. 62-119157),
In some cases, a corrugated washer formed of a material having spring properties is used (see Japanese Utility Model Laid-Open No. 3-117360). However, such a washer has a small bending allowance in the thickness direction, so that when the amount of play of the rotor is large, it is difficult to sufficiently absorb energy with one washer. Further, the structure of the washer is complicated, and the manufacturing cost is increased.

By the way, when assembling the motor, the rotor is inserted into the sliding bearing and the rotor is assembled into the casing with the washer previously inserted into the rotation shaft. Such a washer has a so-called "press-fit washer" whose inner diameter is formed slightly smaller than the outer diameter of the rotating shaft and is inserted into the rotating shaft by press-fitting, and the inner diameter of the washer is made larger than the outer diameter of the rotating shaft to rotate. There is a so-called "idling washer" in which a shaft rotates freely in a washer.

[0010] The press-fit washer is firmly held on the rotating shaft during the work of assembling the rotor, so that the washer does not fall off and the motor assembling work is easy. However, since this pressure washer rotates integrally with the rotating shaft during operation of the motor, if the washer is made of metal, it may repeatedly contact the slide bearing to generate sliding noise or wear the slide bearing. .

On the other hand, since the idling washer is not held on the rotating shaft, there is a possibility that the idling washer may fall off from the rotating shaft during the assembling operation of the rotor. Similarly, when the rotor once assembled is pulled out and then re-assembled in order to finely adjust the play amount of the rotor, the washer may fall off in the same manner.
Since the washer is an extremely small part, if it is dropped from the rotating shaft into the casing and adheres to the slide bearing by impregnating oil of the slide bearing or the like, it is necessary to remove the washer.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problem, and does not fall off from a rotating shaft during a motor assembling operation, and exhibits a spring function during operation of a motor to prevent or reduce motor noise. It is an object of the present invention to provide a small motor having a buffer plate that can be used.

[0013]

In order to achieve the above-mentioned object, a small motor according to the present invention comprises a stator mounted on an inner peripheral surface of a casing, and a stator mounted inside the casing facing the stator. Provided with a rotor, a small motor that rotatably supports a rotating shaft of the rotor by two slide bearings provided in the casing, wherein the rotor and one of the slide bearings are provided. A plurality of through-holes having a predetermined inner diameter larger than the outer diameter of the rotating shaft, the cushioning plate having elasticity and having a predetermined inner diameter larger than the outer diameter of the rotating shaft. The rotating shaft is inserted through the plurality of through holes that are formed by drilling and bending the buffer plate with restoring force.

Preferably, the buffer plate is substantially V-shaped and U-shaped as a whole when attached to the rotary shaft.
Shape, N shape, or W shape.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Small motors are used, for example, in automotive air conditioners, actuators for power windows and door lock mechanisms, electric mirrors, fuel pumps, washer pumps, and other automotive electrical equipment, and audio and video equipment. You.

At present, there is a demand for miniaturization of small motors and peripheral devices, especially in the case of mechanical structures in which sound reverberates outside the motors and small motors used in the audio and video fields. Not preferred. Therefore, in the present invention, by attaching a buffer plate to the rotary shaft, motor noise that has conventionally been generated due to collision or repeated contact between the slide bearing and the rotor is prevented or reduced. In addition to this, the workability is improved by preventing the buffer plate from falling off during the work of assembling the rotor.

An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a front sectional view of a small motor according to the present invention. As shown in the drawing, a small DC motor 20 as a small motor includes a casing 23 in which a stator 22 is attached to an inner peripheral surface 21, and a stator 22.
Rotor 2 provided inside casing 23 so as to face
4 is provided.

The rotor 24 has a rotating shaft 25 extending in the direction of a central axis serving as a center of rotation.
The two slide bearings 26 provided on the casing 23,
27 rotatably supported. Casing 23
Includes a housing 28 and a lid member 30 attached to the housing 28. Slide bearings 26, 27
Are provided at both ends of the casing 23, respectively. The output-side slide bearing 26 is attached to the housing 28, and the opposite-side slide bearing 27 is attached to the lid member 30.

A pair of permanent magnets 22 as a stator are fixed to the inner peripheral surface 21 of the housing 28. A cylindrical projection 38 is integrally formed at the center of the output side surface 37 of the housing 28, and the slide bearing 26 is press-fitted and fixed to the inner peripheral surface of the projection 38. One of the slide bearing portions 26 rotatably supports the rotating shaft 25 on the output portion 39 side, and the output portion 39 of the rotating shaft 25 is provided with a worm 44 constituting a speed reduction mechanism. The other slide bearing portion 27 rotatably supports the non-output portion side of the rotary shaft 25.

A plate-shaped metal supporting member 42 is press-fitted and fixed to the rotating shaft 25 of the rotor 24.
Are located near the slide bearing 26 on the output side.
A washer 50 as a buffer plate is provided between the slide bearing 26 and the support member 42. Thus,
The washer 50 is disposed between the rotor 24 and one of the slide bearings 26 and is inserted into the rotating shaft 25. The washer 50 absorbs the play amount of the rotor 24 in the thrust direction and Rotor 24 and slide bearing 26
Acts as a spring between the two.

FIG. 2 is an explanatory diagram showing the structure and operation of the washer 50. (A) shows the configuration of the washer 50 before being inserted into the rotating shaft 25, and (B) shows the washer 50 being inserted into the rotating shaft 25 and the rotor 24 is incorporated into the housing 28. The state at the time of work is shown, and (C) in the figure shows the state after the completion of assembling.

As shown in FIG. 2, the washer 50 has a flat plate shape having elasticity. A plurality of (two in the present embodiment) through holes 51 having a predetermined inner diameter D larger than the outer diameter d of the rotating shaft 25 are formed in the washer 50. The rotating shaft 25 is inserted through a plurality of through holes 51 aligned in a straight line by bending the washer 50 with a restoring force for returning to the original shape. Since the inner diameter D of the through hole 51 is larger than the outer diameter d of the rotating shaft 25, the rotating shaft 25 can be easily inserted from one through hole 51 of the bent washer 50 into the other through hole 51.

The washer 50 is made of a material which is resilient and does not break due to bending. The washer 50 is made of resin, rubber-based material, metal, or the like in accordance with the state of use, the environment, and the material of the sliding bearing portion 26. Materials are used.
As a material of the washer 50, for example, a polyester resin such as polyester is preferable, but a metal material having a spring property, for example, phosphor bronze for spring, beryllium copper, stainless steel, steel material, or the like may be used.

The washer 50 is formed by punching two symmetrically arranged through holes 51 through which the rotary shaft 25 passes. The outer peripheral surface of the washer 50 is formed by partially overlapping two circles having an outer diameter L. It has a shape. As a result, a narrow portion 52 having a narrow width (width dimension b) is formed between the two through holes 51, so that it is easy to bend. Constriction 5
When the washer 50 is bent at 2 and the rotary shaft 25 is passed through both the through holes 51, the washer 50 has a substantially V shape as a whole when viewed from the lateral direction.

By setting the thickness of the washer 50 and the width b of the constricted portion 52 to appropriate values in accordance with the mass of the rotor 24 and the thrust load P applied to the rotor 24, the bent washer 50 is formed. Can be fine-tuned so that the restoring force becomes an appropriate value. The outer diameter L of the washer 50 is adjusted as needed.

Next, the procedure of the operation of incorporating the rotor 24 into the housing 28 will be described. The flat washer 50 or the washer 50 which has been slightly bent in advance at the constricted portion 52 is bent into a substantially V shape with a restoring force as shown in FIG.

Next, the washer 5 from the output portion 39 side of the rotating shaft 25 to which the support member 42 and the insulating plate 43 are attached.
Install 0. That is, the rotating shaft 25 is made to pass through both the through holes 51 of the washer 50 bent into a substantially V shape. At this time, the washer 50 has a V-shape that expands to both sides due to the restoring force F that is going to return to the original shape, so that the inner peripheral edge of the through hole 51 is pressed against the rotating shaft 25. as a result,
The washer 50 is firmly held on the rotating shaft 25 by the spring function as if it were the "press-fit washer" described above.

Next, the rotating shaft 25 is inserted into the slide bearing 26 on the output side, and the rotor 24 is assembled into the housing 28. During this assembling work, the washer 50
Due to the restoring force F, the rotating shaft 2
5, it does not fall off the rotating shaft 25, and the workability is improved. As a result, FIG.
As shown in (C), the washer 50 is positioned while being sandwiched between the support member 42 and the slide bearing 26. Thus, the play amount of the rotor 24 in the thrust direction is absorbed by the washer 50 inserted into the rotating shaft 25.

The washer 50 after completion of the assembling has a V-shape which is further bent and narrowed as compared with the shape at the time of the assembling operation. The inner diameter D of the through hole 51 is
, The washer 50 is loosely fitted to the rotating shaft 25. As a result, the washer 50 does not rotate together with the rotating shaft 25 and is in a non-rotating state. That is, this is the same state as when the above-mentioned "idling washer" is attached.

Thus, the rotor 24 and the slide bearing 26
The rotor 24 is urged to the non-output side via the support member 42 by the spring function of the washer 50 interposed between the rotor 24 and the rotor. During operation of such a motor, the rotor 24 slides with respect to the washer 50 in the non-rotating state, so that the sliding noise is not easily generated due to the rotation of the washer and the wear of the slide bearing portion 26 does not occur.

Next, the operation will be described. As shown in FIG. 1, in the motor 20, when a current is applied to the rotor 24 via a brush (not shown) and a commutator (not shown), the rotor 24 is located inside the pair of permanent magnets 22. Make a rotary motion. As a result, the rotating shaft 25 rotates, and the electric equipment for a vehicle (not shown) and the like are rotationally driven via the speed reduction mechanism including the worm 44.

The washer 50 interposed between the sliding bearing portion 26 and the rotor 24 in a bent shape exerts a spring function because it attempts to return to the original shape. As described above, since the washer 50 having the restoring force exerts a spring function, the rotor 24 is suddenly pulled to the output side by the thrust load P by the worm 44 when the rotation of the motor 20 starts or when the load changes. In addition, it is possible to reduce a shock such as a collision or repeated contact between the rotor 24 and the slide bearing 26. This can prevent or reduce motor noise such as collision noise (trick noise) and repeated contact noise.

Since the rotor 24 does not directly contact the sliding bearing portion 26, the vibration of the casing 23 is prevented, and it is possible to prevent the sound from reverberating on the device to which the motor 20 is mounted and on the periphery thereof. The washer 50 of the present invention is particularly effective for countermeasures against the clicking noise of the motor in which the worm 44 is attached to the output part 39 of the rotating shaft.

Even when the washer 50 is pressed from both sides until it is crushed, the sound due to the contact between the both sides of the washer 50 is at a considerably low level. In particular, if the washer 50 is made of resin, almost no sound is generated. Further, as compared with a conventional washer having a wavy shape, a washer having irregularities, or the like, the washer 50 of the present invention can be easily manufactured by punching, so that the manufacturing cost can be reduced.
If burrs are formed on the punched end surface of the washer 50, the motor noise due to the burrs can be prevented by bending the washer 50 so that the burrs face inward.

The spring function cannot be exerted with a single flat washer which has been conventionally used, and the warpage allowance of a conventional uneven washer or a wavy washer is extremely small. It has been difficult to prevent or reduce the noise when moving and colliding with the bearing and repeatedly contacting it. On the other hand, since the washer 50 of the present invention has a large bending allowance, the spring function can be sufficiently exhibited to prevent or reduce the motor noise, and the play of the rotor 24 in the thrust direction can be increased. Can be taken.

FIG. 3 is an explanatory view showing the structure of a washer as a buffer plate according to another embodiment of the present invention. Note that the same or corresponding parts as those of the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted. As shown in FIG. 3, the washer is preferably formed with a narrow constriction located between adjacent through-holes, and the washer is bent at the constriction and attached to the rotating shaft. In a state of being turned, it is substantially V-shaped, U-shaped, N-shaped or W-shaped.

Each of the illustrated washers is formed of a flat plate, and the washers 6 shown in FIGS.
Numerals 0 and 61 are elongated and have a substantially rectangular shape. Between the two through holes 51, a constricted portion 62 formed by a curved notch 67 or a constricted portion 63 formed by a substantially rectangular notch 68 is formed. In addition, as shown in (C) in the figure, the entire washer 64 may be formed in an oval shape, and may be a case where there is no constricted portion. These washers 60, 61, 64 are substantially V-shaped or U-shaped when bent.

In the washer 65 shown in FIG. 4D, three through holes 51 are formed in a straight line at the same pitch, and three constricted portions 5 are provided between the adjacent through holes 51.
2 are formed. This washer 65 is attached to the constricted portion 52.
In the figure, and bend it in turn to attach it to the rotating shaft 25.
As shown in FIG. 5, the washer 65 is substantially N-shaped as a whole.

In the washer 66 shown in (F) of the figure, four through holes 51 are bored in a straight line at the same pitch.
A constricted portion 52 is formed between the adjacent through holes 51, 51. Therefore, as shown in (G) in the drawing, the washer 66 has a substantially W shape as a whole when it is sequentially bent at the constricted portion 52 and attached to the rotating shaft 25.

Such N-type and W-type washers 65, 6
According to 6, since the deflection allowance can be made extremely large and freely, it is effective if applied to a motor having a large play amount. In addition, the constricted part formed in the washer may be formed by a linear cut in place of each notch.

Next, a description will be given of a noise measurement experiment conducted by the inventor. FIG. 4 is a schematic explanatory view of the experimental apparatus. As shown in the figure, a resonance box 71 was placed on a base 70 made of sponge, and a motor M was fixed on the upper surface of the resonance box 71 via a rubber material 73. The measuring device 72 was installed at a position 10 cm away from the motor in the horizontal direction, and the noise of the motor M was measured.

When the conventional flat washer 9 shown in FIG. 5 is attached to each of ten motors (that is, a conventional product), the washer is replaced with a washer 50 of the present invention shown in FIGS. 1 and 2. (Ie, the motor 2 shown in FIG. 1)
0: the product of the present invention). The material of both washers 9, 50 is polyester. When the motor is rotated and a predetermined thrust load P is applied to the rotating shaft and pulled toward the output side, a collision sound (so-called clicking sound) generated when the rotor collides with the slide bearing portion on the output side. Was measured. For 10 motors, M
The noise measurement was performed three times in the ax Hold mode, and the maximum value is shown in Table 1.

[0043]

[Table 1]

As can be seen from Table 1, the average value of motor noise due to click noise is 73.65 [dB] in the conventional product, while it is 50.14 in the product of the present invention.
It was confirmed that it was reduced to [dB].

As described above, if the washer of the present invention is mounted on the rotating shaft, the washer exerts the same function as the above-mentioned press-fit washer due to its restoring force when the rotor is assembled. . As a result, the operation of assembling the motor is improved. After the assembly is completed, the washer is in a non-rotating state and exerts a spring function similarly to the above-mentioned idling washer, thereby preventing the rotor from colliding or contacting the sliding bearing portion. as a result,
Motor noise can be prevented or reduced. As described above, in the present invention, one washer sequentially performs the function of preventing falling off and the function of preventing noise, etc., with time.

Although the control of the play of the rotor is an important dimension control in the manufacture of the motor, according to the present invention, since the washer has a spring function, the fine adjustment of the play can be performed more strictly than before. There is no need to do it. Accordingly, in the motor manufacturing process, the dimensional control of the play amount of the rotor becomes easy. The present invention can be applied to a small motor using a sliding bearing, such as a brushless motor and a stepping motor, in addition to the above-described motor with a commutator. The same reference numerals in the drawings indicate the same or corresponding parts.

[0047]

Since the present invention is constructed as described above, the buffer plate does not fall off the rotating shaft due to the restoring force at the time of assembling the motor. In addition, the above-mentioned buffer plate exerts a spring function to prevent or reduce motor noise.

[Brief description of the drawings]

FIGS. 1 to 4 show one embodiment of the present invention, and FIG. 1 is a front sectional view of a small motor.

FIG. 2 is an explanatory view of the configuration and operation of a buffer plate attached to the small motor shown in FIG.

FIG. 3 is an explanatory diagram showing a configuration of a buffer plate according to another embodiment.

FIG. 4 is a schematic explanatory view of an experimental apparatus.

FIG. 5 is a sectional view showing a part of a conventional small motor.

[Explanation of symbols]

Reference Signs List 20 small DC motor (small motor) 21 inner peripheral surface 22 permanent magnet (stator) 23 casing 24 rotor 25 rotation shaft 26 one sliding bearing 27 sliding bearing 50, 60, 61, 64 to 66 washer (for buffer) 51) Through hole d Outer diameter of rotating shaft D Inner diameter of through hole

Claims (2)

[Claims] A stator (22) mounted on an inner peripheral surface of a casing (23); and a rotor (24) provided inside the casing so as to face the stator. Two slide bearings (26,
27) A small motor for rotatably supporting a rotating shaft (25) of the rotor according to 27), wherein the small motor is disposed between the rotor and one of the sliding bearing portions (26) and is attached to the rotating shaft. The cushioning plate (50, 60, 61, 6) having an inserted cushioning plate and having elasticity.
4 to 66), a plurality of through-holes having a predetermined inner diameter (D) larger than the outer diameter (d) of the rotating shaft are formed, and the buffer plate is bent with a restoring force to be linear. A small motor, wherein the rotating shaft is inserted through the plurality of through holes arranged in a line. 2. The buffer plate according to claim 1, wherein the buffer plate has a substantially V shape, a U shape, an N shape, and a W shape when attached to the rotating shaft. The small motor according to the above.