JP2001119906A - Motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor, capable of constituting its rotor core using core sheets having the same shape, and capable of correcting unbalance of the mass of its rotor. SOLUTION: In a motor which has the center of gravity of its rotor 9 provided with a core 19 composed of a laminate of steel plates at a position deviating from its rotation center, and has a mass-balance adjusting balance weight 14 fitted to one end of the shaft of the rotor 9, a mass-balance adjusting groove 19b stretching over the whole axial direction of the core 19 of the rotor 9 is formed in the peripheral part of the core 19. The adjusting groove 19b is formed at a position deviating in the same direction as the direction of deviation of the center of gravity of the balance weight 14, and unbalance of the mass of the rotor is corrected by the balance weight and the mass-balance adjusting groove.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor in which the center of gravity of a rotor is eccentric with respect to the center of rotation.

[0002]

2. Description of the Related Art An electric motor for driving a load such as an oil pump in which a movable portion reciprocates linearly has an output shaft portion eccentric with respect to the rotation center of a rotating shaft of a rotor. A bearing such as a needle bearing or a ball bearing is attached to the output shaft, and the load is driven by transmitting the eccentric rotation of the output shaft to a movable portion of the load via the bearing. For example, in a plunger type pump, the eccentric rotation of the output shaft of the electric motor is transmitted to the plunger via a bearing attached to the output shaft.

In some motors, the cross section of the output shaft at the end of the rotary shaft is D-cut in order to couple the load to the end of the rotary shaft of the rotor in a detent structure. An unbalanced portion may be formed, or an unbalanced portion of the mass may be formed in a portion other than the output shaft portion of the rotor due to the design of the motor.

[0004] In such a motor, the center of gravity of the output shaft and other parts is eccentric with respect to the center of rotation, so that imbalance occurs when the rotor rotates, causing vibration and noise. In order to prevent this, a balance weight for adjusting the mass balance is attached to one end of the rotating shaft of the rotor.

However, when the position of the center of gravity is eccentric in the output shaft portion and other portions, the position of the center of gravity and the position of the center of gravity of the balance weight are eccentric in directions opposite to each other with respect to the center of rotation of the rotor. Because they are separated by a certain distance in the axial direction of the shaft,
A bending moment is applied to the rotating shaft by the centrifugal force generated in each of the portion where the center of gravity is eccentric and the balance weight. Therefore, it is not possible to completely remove the imbalance that occurs when the rotating shaft rotates, which may cause vibration and noise.

In order to prevent this, in a conventional motor,
The example shown in FIG. 8 (the eccentric output shaft portion 1 of the rotating shaft 10 of the rotor)
0a and the bearing 13 fitted to the output shaft portion causes an imbalance in mass, as in the example), the eccentric direction of the center of gravity of the output shaft portion of the coil end of the armature coil 21 wound around the core 19. The putty 22 is attached to the position in the same direction as the above, so that the combined centrifugal force generated in the output shaft portion and the putty 22 and the centrifugal force generated in the balance weight 14 are offset.

Further, in a motor having an eccentric output shaft proposed in Japanese Patent Application Laid-Open No. 7-231623, as shown in FIG. 9, core sheets 19c for adjusting the mass balance are provided at both ends of a laminated core 19 constituting a rotor. And 19d are stacked to arrange the mass balance. In this case, the core sheet 19c arranged on the output shaft portion 10a side of the rotating shaft 10 has a yoke portion (a slot near the rotating shaft) formed so as to be positioned on the same side as the eccentric direction of the output shaft portion 10a. 1 to 5 holes 19
In the core sheet 19d provided with c1 and disposed on the opposite side to the output shaft portion 10a, one to five holes are provided in the yoke portion thereof in a state where the core sheet 19d is located in a direction opposite to the eccentric direction of the output shaft portion 10a. 19d1 is provided.

In this motor, the core sheets 19c and 1
9d is laminated (1 to 20 sheets) necessary to correct the imbalance of the output shaft portion 10a, and the combined centrifugal force generated in the eccentric output shaft portion 10a and the core sheet 19d and the core sheet 19c By canceling out the generated centrifugal force, the unbalance of the rotor is eliminated.

[0009]

Among the above-mentioned conventional motors, as shown in FIG. 8, a putty for mass balance adjustment is put on a coil end of an armature coil for mass balance adjustment of a rotor. If so, the putty put on during the rotation may be scattered and the balance may be lost, which is not preferable.

Also, in the electric motor (FIG. 9) proposed in Japanese Patent Application Laid-Open No. 7-231623, it is necessary to laminate core sheets having different shapes when forming a laminated core, so that the production of the core is complicated. There was a problem. In particular, when punching and laminating a core sheet by a progressive lamination press die, two types of core sheets having different shapes between a core sheet having holes and a core sheet having no holes are used. It is necessary to add a mechanism such as a jump cut in order to punch out and stack a predetermined number of sheets, and there is a problem that the manufacturing of the stacked mold is complicated and the cost is increased.

[0011] It is an object of the present invention to eliminate the imbalance generated during rotation of a rotor without attaching a putty for mass balance adjustment to an armature coil or using a device having a complicated structure when forming a laminated core. An object of the present invention is to provide an electric motor capable of performing correction.

[0012]

SUMMARY OF THE INVENTION According to the present invention, there is provided a rotor provided with a core comprising a laminated body of steel sheets, wherein the center of gravity of the rotor is eccentric with respect to its center of rotation, and a mass is provided at one end of the rotating shaft of the rotor. The present invention relates to an electric motor to which a balance weight for balance adjustment is attached.

According to the present invention, a groove for adjusting the mass balance extending along the axial direction of the core portion of the rotor is formed on the outer peripheral portion of the core portion of the rotor over the entire axial direction of the core portion of the rotor. Then, the mass balance of the rotor is corrected by the balance weight and the groove for adjusting the mass balance.

With the above construction, the center of gravity of the core portion is located at a position deviated to the side opposite to the groove for adjusting the mass balance, and the combined centrifugal force generated in the eccentric output shaft portion and the core portion and the balance weight And the centrifugal force generated in
Correction of the rotor imbalance can be performed.

Since the grooves for adjusting the mass balance formed in the rotor are formed over the whole of the core portion of the rotor in the axial direction, all the core sheets constituting the laminated core may have the same shape. Even when a laminated core is manufactured by punching a core sheet (steel plate) having a concave-convex fitting portion with a feeding lamination type press and successively laminating and fitting the fitting portions of adjacent core sheets to each other. No complicated mechanism such as a jump cut mechanism is required.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIGS. 1 to 3 show an example of a configuration in which the present invention is applied to a DC motor with a brush.
FIG. 2 is a longitudinal sectional view showing the entire structure of the electric motor. FIG.
(A) and (B) show the rotor of the electric motor of FIG. 1, (A) is a side view showing a half section thereof, (B)
FIG. 2 is a front view of the rotor. FIG. 3 is a front view showing a core sheet constituting a laminated core of the rotor.

In FIG. 1, reference numeral 1 denotes a case in which an iron plate is formed in a substantially cup shape, and 2 denotes an annular permanent magnet which is fixed to the inner periphery of a peripheral wall 1a of the case 1 and forms a field of a motor. 1 and the permanent magnet 2 constitute a stator of the electric motor. Reference numeral 3 denotes a front cover made of an iron plate, and the front cover is fixed to the case 1 in a state where its outer peripheral portion is press-fitted into the inner peripheral portion of the peripheral wall of the case 1 on the opening side. Reference numeral 4 denotes a brush holding plate made of an insulating material fixed to the inside of the front cover 3, and the brush holding plate has a pair of brush holders 5, 5 opposed in one direction.
And another pair of brush holders (not shown) facing each other in a direction perpendicular to the facing direction of these brush holders. The brushes 6 are respectively held by the two pairs of brush holders 5 and are urged by a coil spring 7.

Since the illustrated motor is a four-pole brushed motor, two pairs of brushes 6 are provided as described above, and a pair of brushes facing each other are electrically connected to the front cover 3. The other pair of brushes is electrically connected to the female input terminal fitting 8 inserted into the insulating member 801 held by the front cover 3.

Reference numeral 9 denotes a rotor of the electric motor. A portion of the rotary shaft 10 near the output shaft portion 10a of the rotor 9 is fitted to a front bearing holding portion 3a formed at the center of the front cover 3. And is supported by the front side ball bearing 11. An end on the rear side (opposite to the output shaft) of the rotation shaft of the rotor 9 has a rear ball bearing 12 fitted in a rear bearing holding portion 1b formed at the center of the bottom wall of the case 1. Supported by

The output shaft portion 10a of the rotating shaft 10 of the rotor 9 extends through the front cover 3 to the outside. In the illustrated motor, the output shaft portion 10a is an eccentric shaft eccentric with respect to the rotation center axis of the rotating shaft 10, and a bearing 13 is fitted to the eccentric shaft. A balance weight 14 for adjusting the mass balance is attached to a portion of the rotary shaft 10 adjacent to the output shaft portion 10a by pressure fitting. A bush 1 for preventing the bearing 13 from coming off is provided at the tip of the rotating shaft 10 on the output shaft portion 10a side.
7 is fixed.

An armature 15 and a commutator 1 are
In this example, the rotor 9 is constituted by the rotating shaft 10, the armature 15 and the commutator 16, the balance weight 14 for adjusting the mass balance, the bearing 13, and the bush 17.

The armature 15 is obtained by winding an armature coil around a core 19 formed by laminating a predetermined number of core sheets 18 of a steel sheet having a predetermined shape as shown in FIG. In the illustrated example, the core 1 has twelve salient poles 19a, 19a,.
An armature 15 is constituted by 9 and an armature coil 21 wound around a slot of the core via an insulating bobbin 20, and a terminal of each winding of the armature coil is connected to a commutator 16. . The core 19 and the commutator 16 are fixed to the rotating shaft 10 by press fitting.

Balance weight 1 for mass balance adjustment
4 is disposed closer to the armature 15 than the output shaft portion 10a (unbalanced portion), and is press-fitted and fixed to a balance weight fitting shaft portion 10b sharing an axis with the rotation center line of the rotating shaft 10. I have. As shown in FIG. 5A, for example, the balance weight 14 is made of a metal formed such that the center of the hole 14a fitted to the balance weight fitting shaft portion 10b is eccentric to the center of the outer circumference circle. The center of gravity of the annular body is located at a position eccentric in the direction opposite to the eccentric direction of the axis of the output shaft portion 10a with respect to the rotation center line of the rotating shaft 10, and the bearing 13
Are fixed to the balance weight fitting shaft portion 10b with a slight gap between them.

The shape of the balance weight 14 for adjusting the mass balance is arbitrary. For example, as shown in FIG.
It is also possible to use a balance weight having a shape in which the thickness of the half-peripheral portion of the peripheral portion of the hole 14a to be fitted into the hole is different from the thickness of the other half-peripheral portion.

The bush 17 is made of metal.
Bush fitting shaft portion 10 sharing an axis with the rotation center line 0
c.

A front-side ball bearing 1 (not shown) is attached to a front bearing fitting shaft portion 10d of the rotating shaft 10.
1 is fitted. Front bearing fitting shaft 10d,
The outer diameter of each of the balance weight fitting shaft portion 10b and the eccentric output shaft portion 10a is set so that the front ball bearing 11, the balance weight 14, and the bearing 13 can be sequentially mounted from one end of the rotating shaft.
They are provided in a state where their outer diameters are sequentially reduced.

The illustrated core 19 is obtained by sequentially laminating core sheets 18 formed by punching, and fitting the fitting portions formed on each core sheet itself to the fitting portions of the adjacent core sheets. This is a core manufactured by a known progressive lamination method in which sheets are sequentially bonded. FIG. 7 shows an example of a core connection structure manufactured by the progressive lamination method.
It was shown to.

As shown in FIG. 3, the core sheet 18 constituting the core 19 has a large number (12 in the illustrated example) of salient pole portions 18a projecting from the outer periphery of the annular yoke portion. A concave portion 18b is formed in the outer peripheral portion of one salient pole portion 18a among the salient pole portions 18a, 18a,. The yoke portion of the core sheet 18 has a fitting portion 18c which is formed on one side in the thickness direction (in the example shown in FIG. 7, the fitting portion 18c has a substantially cup-shaped forming portion).
Are formed.

A series of core sheets 18 constituting the laminated core 19 are all formed in the same shape, and the core sheets 18 formed sequentially by punching a steel plate are
As shown in FIG. 7, the fitting portions 18c provided on each of the stacked core sheets 18 have the fitting portions 18c formed on the adjacent core sheets.
Each core sheet 1 is fitted (press-fit) to
8 are bonded to an adjacent core sheet 18 to form a core 19.

A core 19 composed of a laminate of core sheets 18
A groove 19b for adjusting the mass balance extending over the entire core in the axial direction is formed by the concave portion 18b in the outer peripheral portion (see FIG. 2).

The core 19 is provided with a groove 19 for adjusting the mass balance.
b is pressure-fitted to the rotating shaft 10 in a state where it is positioned on the same side as the direction of deviation of the center of gravity of the balance weight 14, and the eccentric output shaft 10a and the eccentricity are formed by the balance weight 14 and the mass balance adjusting groove 19b of the core. The imbalance of the rotor mass due to the needle bearing 13 fitted to the output shaft is corrected.

As described above, according to the present invention, since the core 19 can be formed by laminating only core sheets having the same shape, the core sheet can be continuously punched and laminated by the progressive lamination method. In addition, a complicated mechanism such as a jump cut mechanism is not required. When press-fitting and fixing the core to the rotating shaft of the rotor, it is necessary to position the groove 19b for mass balance adjustment in a predetermined direction with respect to the rotating shaft.
This positioning can be easily performed using the groove 19b for adjusting the mass balance (for example, by fitting a jig for positioning into the groove 19b), so that a special mechanism for positioning the core is provided. The assembly of the rotor can be performed without the need.

Therefore, according to the present invention, it is possible to easily manufacture the rotor of the electric motor and reduce the cost of the electric motor.

FIG. 4 is a mechanical concept diagram for explaining the mass balance of the rotor in the illustrated example.

In FIG. 4, it is assumed that the mass imbalance of the rotor armature 15 is only due to the mass balance adjusting groove 19b formed in the core 19, and there is no mass imbalance due to the armature coil. Suppose The core 19 has a mass of an unbalanced mass portion 19b '(portion indicated by a broken line in FIG. 4) having a volume corresponding to the volume of the groove 19b imagined at a position symmetrical to the groove 19b with respect to the rotation center of the rotation shaft. It is considered to be added as unbalanced mass.

In FIG. 4, the unbalanced masses generated in the rotor are the one eccentric output shaft portion 10a, the needle bearing 13, the two balance weights 14, and the three-core unbalanced mass portion 19b '. The symbols for the mass, the position of the center of gravity, the amount of eccentricity of the position of the center of gravity, the axial distance between the positions of the centers of gravity, and the symbols of the eccentric load (centrifugal force) when the rotor rotates are set as shown in Table 1, and the conditions of balance will be considered.

[0038]

[Table 1] Here, assuming that the rotational angular velocity of the rotor is ω, the eccentric load (centrifugal force) of each part is given by the following equation.

Fe = Me · re · ω ² (2) Fb = Mb · rb · ω ² (3) Fc = Mc · rc · ω ² (4) The balance condition is expressed by the following equation.

Fe + Fc = Fb (5) Fe · le = Fc · lc (6) In a rotor in which the values of the masses Me · re and the distances le and lc between the centers of gravity are fixed, the imbalance is corrected. Of the balance weight 14 and the value of Mc · rc of the unbalanced mass portion 19b 'corresponding to the mass balance adjusting groove 19b of the core are calculated by the above equation (5).
From (6), the following is obtained.

Mb · rb = Me · re (1 + le / lc) (7) Mc · rc = Me · re × le / lc (8) Accordingly, the shape, dimensions and material specific gravity of the balance weight 14 and the core By selecting the dimensions of the mass balance adjusting groove 19b so as to satisfy the above equation, it is possible to correct the imbalance when the rotor 9 rotates.

In the above example, the groove 1 for adjusting the mass balance is used.
Although only one 9b is provided, the present invention is not limited to this. If necessary, as shown in FIG. 6, a plurality of core sheets 18 (three in the example shown in FIG. 6) A concave portion 18b may be formed in the outer peripheral portion of each salient pole portion 18a, and a plurality of grooves 19b for adjusting the mass balance may be formed in the outer peripheral portion of the core. When a plurality of grooves 19b for adjusting the mass balance are provided in this manner, the plurality of grooves 19b
May be formed on the outer peripheral portions of a plurality of adjacent salient pole portions, respectively, or may be formed on the outer peripheral portions of a plurality of remote salient pole portions.

In the above example, the balance weight 14 is provided in the unbalanced portion (in the above example, the eccentric output shaft portion 10a).
Since the groove 19b is located closer to the core 19, the mass balance adjusting groove 19b is provided at a position deviated in the same direction as the direction of deviation of the center of gravity of the balance weight 14, but the balance weight 14 is provided at the unbalanced portion. In the case where the balance weight 14 is provided on the opposite side to the core 19 (when the balance weight 14 is attached to the right side of the output shaft portion 10a in FIG. 1), the groove 19b for adjusting the mass balance is provided with the center of gravity of the balance weight 14. It is provided at a position deviated in the direction opposite to the direction of deviation.

In the above description, the case where the present invention is applied to a DC motor with a brush is taken as an example. However, the center of gravity of a rotor having a core made of a laminated body of steel plates is located at an eccentric position with respect to the center of rotation. The present invention can be applied to a motor in which a balance weight for adjusting the mass balance is attached to one end of the rotating shaft of the rotor, such as a brushless motor. With the shaft portion and the needle bearing fitted to the output shaft portion, when the center of gravity of the rotor is at an eccentric position with respect to the center of rotation, a balance weight for mass balance adjustment and the outer periphery of the rotor are formed. The mass balance adjustment groove corrects the mass balance of the rotor, but is directly aligned with the axis of the output shaft provided at one end of the rotor shaft. The cross section is D-cut so as to exhibit a D-shape, so that the position of the center of gravity of the output shaft portion is eccentric, or the other portion of the rotor has a design imbalance in mass. The present invention can also be applied to a case where the center of gravity is at a position eccentric with respect to the center of rotation.

When the rotor has a mass imbalance due to a manufacturing error, the imbalance is corrected separately.

[0046]

As described above, according to the present invention, a groove for adjusting the mass balance extending over the entire axial direction of the rotor is formed in the outer peripheral portion of the core of the rotor, so that the rotor can be rotated during rotation. Since the resulting mass imbalance in design is corrected, the core can be easily formed by stacking only core sheets of the same shape. Therefore, according to the present invention, there is an advantage that the assembly of the rotor can be facilitated and the cost of the electric motor can be reduced.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a configuration example of a motor to which the present invention is applied.

FIGS. 2A and 2B show a rotor used in the electric motor shown in FIG. 1, wherein FIG. 2A is a side view showing an upper half section, and FIG. 2B is a front view.

FIG. 3 is a front view showing an example of a shape of a core sheet constituting a core of the rotor shown in FIG. 2;

FIG. 4 is an explanatory diagram of a dynamic concept of a mass balance of the rotor shown in FIG. 2;

FIGS. 5A and 5B are front views showing different examples of balance weights used in a motor to which the present invention is applied.

FIG. 6 is a front view showing another example of the shape of the core sheet constituting the core of the rotor shown in FIG. 2;

FIG. 7 is a cross-sectional view illustrating a coupling structure of a progressive stack type core.

FIG. 8 is a side view showing a cross section of an upper half of a rotor of a conventional motor.

FIG. 9 is a side view showing a cross section of an upper half of a rotor of another conventional electric motor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Case, 2 ... Permanent magnet, 9 ... Rotor, 10 ... Rotary shaft, 10a ... Output shaft part, 10b ... Balance weight fitting shaft part, 10c ... Bush fitting shaft part, 10d ... Front bearing fitting shaft part, 11 front ball bearing, 12 rear ball bearing, 13 needle bearing, 14 balance weight, 15 armature, 1
8 core sheet, 18b recess, 19 core, 19a
Salient pole portion, 19b: groove for adjusting the mass balance.

Continued on the front page F term (reference) 5H607 AA04 BB01 BB04 BB14 CC01 CC03 CC05 DD02 EE44 FF06 5H615 AA01 BB01 BB04 BB14 PP02 PP06 SS54

Claims (1)

[Claims] 1. A rotor provided with a core made of a laminated body of steel sheets, a center of gravity of which is eccentric with respect to a rotation center thereof, and a balance weight for adjusting a mass balance is attached to one end of a rotation shaft of the rotor. In the electric motor, a groove for adjusting the mass balance extending along the axial direction of the rotor is formed in the outer peripheral portion of the core portion of the rotor throughout the axial direction of the core portion of the rotor. An electric motor characterized in that the imbalance of the mass of the rotor is corrected by the mass balance adjusting groove.