JP4250389B2 - motor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a motor such as a brushless DC motor, and more particularly to a motor that reduces vibration and noise and improves the motor cooling effect.
[0002]
[Prior art]
Brushless DC motors (hereinafter referred to as BLDC motors) are generally provided with motor parts such as a stator and a rotor in a motor frame. The motor frame is composed of a cylindrical motor housing portion for housing the motor portion, and a substantially annular flange extending outward from the motor housing portion for assembling the BLDC motor to the apparatus or the like. The motor frame is provided with a bracket for supporting a motor member such as a rotor.
[0003]
Conventionally, ribs for reinforcing the frame are formed on the flange, and are usually provided at equal intervals on the circumference of the flange centered on the motor rotation shaft.
[0004]
However, the number of reinforcing ribs provided on the flange is not particularly specified. For example, in an 8-pole 12-slot motor, six, eight, twelve, sixteen reinforcing ribs are provided on the flange circumference. Depending on the number of ribs, the reinforcing rib may synchronize with the number of rotations as the motor rotates, causing a resonance phenomenon, and the motor frame may be in a resonance state to increase vibration and noise.
[0005]
On the other hand, in a BLDC motor equipped with a motor drive circuit inside, a cooling device such as a heat sink is provided to dissipate heat generated by the motor drive circuit, and heat generated by the drive circuit is dissipated to suppress overheating of the motor. Drive normally and improve durability.
[0006]
However, when the amount of heat generated in the motor drive circuit increases, the cooling capacity of the heat sink becomes insufficient, and when the heat sink is enlarged to increase the cooling effect, the space is required and the size of the BLDC motor is increased. is there.
[0007]
[Problems to be solved by the invention]
The present invention is, that lessens the low generation of vibration and noise, and an object thereof is to provide a particularly motor suitable for a brushless DC motor.
[0008]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a motor having a stator and a rotor in a motor frame, wherein the motor frame includes a motor housing portion and a flange, and the flange provided on a circumference centering on a rotation axis. The number of reinforcing ribs is a number other than a divisor of the number of slots of the stator, a number other than a multiple of the number of slots, and a number other than a divisor of the number of poles of the rotor, and a multiple of the number of poles It is a motor characterized by the number other than.
[0009]
According to the motor of the present invention, it is possible to reduce the vibration and noise generation of the motor unit and the frame by suppressing the resonance of the motor frame by avoiding the resonance phenomenon of the reinforcing rib provided on the flange accompanying the motor rotation. Can do.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0015]
(First embodiment)
FIG. 1 is an external side view of the BLDC motor 1 according to the first embodiment. FIG. 2 is a plan view of the motor frame 2 of the BLDC motor 1.
[0016]
In FIG. 1, a BLDC motor 1 is provided with a motor unit (not shown) including a rotor having a stator and a rotating shaft 11 and a motor drive circuit board (not shown), and the motor unit and the motor frame 2 are bracketed. A cover 15 covering the bottom of the motor is attached to the lower side of the bracket 14 on the upper side of the bracket 14.
[0017]
The motor frame 2 includes a cylindrical motor housing portion 13 for housing the motor portion, and a substantially annular flange 14 extending outward from the bottom of the motor housing portion 13 for assembling the BLDC motor 1 to an apparatus or the like. Further, the flange 12 is provided with an elastic body 16 made of sponge or vibration-proof rubber so as to absorb vibration and prevent vibration transmission to the apparatus.
[0018]
In the motor frame 2, a stator (not shown) having 12 slots fixed in a ring shape on the inner peripheral surface of the motor housing 13, and a rotor having a plurality of magnetic bodies on the inner periphery of the stator. (Not shown) is supported and accommodated by the bracket 14 so as to be rotatable about the rotation shaft 11, and this rotor forms eight magnetic poles.
[0019]
As shown in FIG. 2, the flange 12 of the motor frame 2 is provided with 13 reinforcing ribs 21 at equal intervals on the circumference of the flange 12 around the rotation shaft 11.
[0020]
The reinforcing rib 21 can be integrally formed with the flange 12 at the time of molding in the case of a resin motor frame, and can be provided by integral processing or welding by a press in a metal motor frame. Although the shape and size of the reinforcing rib 21 are not limited, it is preferable to provide the flange 12 with the same shape rib.
[0021]
In the BLDC motor 1, the stator and the rotor have 12 slots and 8 poles, and the flange has 13 reinforcing ribs 21. Therefore, the resonance phenomenon of the reinforcing ribs 21 due to the rotation of the rotor due to energization of the stator occurs. Thus, the motor frame 2 is brought into a resonance state, and vibrations of the motor unit and the frame are promoted and increased, so that generation of motor vibration and noise can be reduced.
[0022]
That is, the number of reinforcing ribs 21 of the flange 12 is a number other than a divisor of the number of slots of the stator, a number other than a multiple of the number of slots, and a number other than a divisor of the number of poles of the rotor. Since there is a relationship that is a number other than a multiple of the number of poles, there is a difference in the natural frequency of the two, so that there is no tuning and the occurrence of a resonance phenomenon is avoided.
[0023]
Therefore, in the case of the 12-slot 8 poles, the number of reinforcing ribs 21 provided on the flange 12 is 5, 7, 9, 10, 11, 13, 14, 15, 17,... The number of ribs such as the above may be mentioned, but it can be provided in consideration of other factors such as frame reinforcement, rib molding, workability, rib shape, and size.
[0024]
And by setting it as such a rib structure, the vibration and noise by a harmonic can also be reduced.
[0025]
(Second Embodiment)
FIG. 3 is a longitudinal sectional view of a BLDC motor 3 according to the second embodiment.
[0026]
The BLDC motor 3 includes a stator 31, a rotor 34, a motor drive circuit board 46, a bracket 45 to which they are attached, a motor frame 40, and a cover 48.
[0027]
The stator 31 includes an iron core 32 and a coil 33, and is arranged and fixed in a ring shape on the inner peripheral surface of the motor housing portion 41 of the motor frame 40.
[0028]
The rotor 34 is arranged on the peripheral surface of a holder 37 that fixes a plurality of magnetic bodies 36 to a rotating shaft 35 so as to face the stator 31, and the rotating shaft 35 is arranged at the center of the bracket 45 via bearings 38 and 39. It is rotatably supported by the projecting cylindrical support portion 45a. The stator 31 and the rotor 34 are housed in the motor housing portion 41, and the motor frame 40 is screwed to the bracket 45 at the flange portion 42.
[0029]
The bracket 45 is formed by die-casting an aluminum material.
[0030]
A motor drive circuit board 46 is arranged in parallel with the bracket 45 in a cover 48 provided on the lower side of the bracket 45, and is attached to the bracket 45 via a spacer 47. An FET 50 that is one of the circuit components that generate heat and is wired on the circuit board 46 is fixed to the bracket 45 with screws 51.
[0031]
In the BLDC motor 3 configured as described above, the FET 50 mounted on the circuit board for driving the motor generates heat when energized, but since this FET 50 is in contact with the aluminum bracket 45, this heat is transmitted to the entire bracket 45, Heat is radiated directly without using other heat radiating means. Note that not only the FET but also a power IC or other electronic components that generate heat may be brought into contact with the bracket.
[0032]
This aluminum bracket 45 has high thermal conductivity and heat is easily transmitted to the entire bracket 45, and the surface area is significantly wider than that of a conventional heat sink, so that heat dissipation efficiency is improved and a sufficient cooling effect can be obtained. The BLDC motor 3 having excellent durability by preventing overheating of the motor unit can be obtained.
[0033]
In the BLDC motor 3 shown in FIG. 3, the air in the motor housing 41 is agitated by the rotation of the rotor 34, and the heat dissipation effect is further improved.
[0034]
Further, the aluminum bracket 45 can be easily formed by die casting, and further, since it has a low density, the weight of the BLDC motor can be reduced.
[0035]
Further, since conventional cooling parts such as a heat sink are not necessary, the number of parts can be reduced and the space can be saved, and the size and cost of the BLDC motor 3 can be reduced.
[0036]
Further, in the structure of the BLDC motor 3 shown in FIG. 3, since the motor driving circuit 48 is hermetically sealed by the bracket 45 and the cover 48, it is possible to prevent intrusion of dust and moisture from the motor unit and the outside, and maintenance of the circuit unit. It can also improve the performance.
[0037]
Further, the BLDC motor 3 is provided with reinforcing ribs 43 on the flanges 42, and the number of ribs other than a multiple or a divisor of the number of slots of the stator and the number of poles of the rotor, as in the first embodiment. Therefore, the resonance of the reinforcing rib 43 due to the rotation of the motor can be prevented, and vibration and noise can be reduced at the same time.
[0038]
【The invention's effect】
As described above, in the motor of the present invention, the number of reinforcing ribs provided on the flange of the motor frame is a number other than a divisor of the number of slots of the stator, a number other than a multiple of the number of slots, and Since it is a number other than a divisor of the number of poles of the rotor and a number other than a multiple of the number of poles, it avoids the resonance phenomenon of the reinforcing rib accompanying the motor rotation, and the vibration and noise of the motor part and the frame. Reduce the occurrence. In addition, vibration and noise due to harmonics can be reduced.
[Brief description of the drawings]
FIG. 1 is an external side view of a brushless DC motor according to a first embodiment.
FIG. 2 is a plan view of a motor frame of the brushless DC motor according to the first embodiment.
FIG. 3 is a longitudinal sectional view of a brushless DC motor according to a second embodiment.
[Explanation of symbols]
1, 3 ... Brushless DC motors 2, 40 ... Motor frames 11, 35 ... Rotating shafts 12, 42 ... Flange 13, 41 ... Motor housing 14 ... Brackets 21, 43 ... Reinforcing ribs 31 ... Stator 34 ... Rotor 45 ... Aluminum bracket 46 ... Motor drive circuit 50 ... FET

Claims (1)

In a motor having a stator and a rotor in a motor frame,
The motor frame is composed of a cylindrical motor housing portion centered on the rotating shaft of the rotor , and a substantially annular flange extending outward from the bottom of the motor housing portion ,
The flange is provided with a plurality of reinforcing ribs formed long in the circumferential direction at equal intervals on a circumference centered on the rotating shaft,
The number of the reinforcing ribs is a number other than a divisor of the number of slots of the stator, a number other than a multiple of the number of slots, and a number other than a divisor of the number of poles of the rotor, A motor characterized by a number other than a multiple of the number.

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