JPH11252854A - Electric motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately and easily perform the positioning of a balancer mounted in a rotary shaft, in an electric motor bringing a plunger into contact with an outer ring of a bearing mounted in an eccentric shaft part provided in a tip end of the rotary shaft for driving this plunger reciprocated linearly. SOLUTION: In this electric motor, an eccentric shaft part 2a is formed in the tip end of a rotary shaft 2, a bearing 3 is mounted in the eccentric shaft part 2a, a linearly driving plunger is brought into contact with an outer ring of the bearing 3, a balance 4 is mounted in a position adjacent to the eccentric shaft part 2a of the rotary shaft 2a, and the unbalance of weight of the rotary shaft is corrected. A notch 4c is formed in a peripheral part of the balancer 4 in a condition of being placed in a position in side opposite to the eccentric direction of the center of gravity of the balancer 4, the balancer 4 is mounted in the rotary shaft 2 with this notch 4c serving as a reference for positioning.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric motor for driving a load which reciprocates linearly in a radial direction of a rotating shaft, such as a plunger of a plunger pump used in an antilock brake system.

[0002]

2. Description of the Related Art For example, in a DC motor for driving a plunger pump for applying a hydraulic pressure to an anti-lock brake system (ABS) of an automobile, as shown in FIGS. 6 (A) to 6 (C), a rotation supported by bearings of the motor. An eccentric shaft portion 2a having a center axis O2 is formed at the tip of the shaft 2 at a position radially eccentric (amount of eccentricity d) with respect to the rotation center axis O1 of the rotary shaft. An outer ring 3a concentrically surrounding an eccentric shaft and a rolling element 3b disposed inside the outer ring
(In this example, a needle bearing) is attached. The plunger of the plunger pump is provided in a pair on the left and right in the radial direction of the rotary shaft 2, and the plunger is urged by an urging means such as a spring or a cylinder to abut the outer ring 3 a of the bearing 3 from the outside. . When the rotating shaft 2 rotates, the bearing 3 moves so that its center axis O2 rotates around the rotation center axis O1, and linearly reciprocates the plunger by the outer ring 3a.

The eccentric shaft portion 2a and the eccentricity of the bearing 3 with respect to the rotation center axis O1 cancel the radial unbalance load generated when the rotation shaft 2 rotates.
A balancer 4 is fitted to a portion adjacent to the eccentric shaft portion 2a with a small gap in the axial direction from the bearing 3.
As a stopper for restricting the movement of the bearing 3 in the axial direction, an annular retainer is provided at a portion on the shaft end side adjacent to the eccentric shaft portion 2a of the rotating shaft 2 with a small gap in the axial direction from the bearing 3. 5 is fitted.

The balancer 4 has a rotation center axis O of the rotation shaft 2.
1 and a straight line extending in the eccentric direction of the eccentric shaft portion 2a along the radial direction of the rotating shaft 2 and is formed in a symmetrical shape with respect to a YY plane (see FIG. B). As shown in FIGS. 6 (b) and 7, the balancer 4 used in a conventional motor of this type has an inner peripheral surface 4a fitted to a rotating shaft having a rotation center axis O1 as a center axis. In addition to being formed so as to have a cylindrical surface shape, the outer peripheral surface 4b is formed so as to have a cylindrical surface shape having a center axis O3 at a position radially eccentric with respect to the rotation center axis O1. The balancer is positioned so that its center of gravity is located on the side opposite to the eccentric direction of the eccentric shaft portion 2a with respect to the rotation center axis O1, and is fitted to the rotation shaft.

[0005]

The balancer needs to be fitted to the rotating shaft so that the center of gravity of the balancer is accurately located on the side opposite to the eccentric direction of the eccentric shaft with respect to the center axis of rotation of the rotating shaft. However, in the balancer used in the conventional motor, the rotation center axis (the center axis of the inner peripheral cylindrical surface of the balancer)
Since there is no positioning portion indicating the eccentric direction of the position of the center of gravity of the balancer with respect to the above, there is a problem that when the balancer is fitted to the rotating shaft, the positioning is troublesome and the manufacturing cost is increased.

Further, in the conventional motor, it is difficult to improve the positioning accuracy of the balancer, and it is difficult to eliminate the unbalance load generated in the radial direction of the rotating shaft when the motor is rotated. There was a problem that it was unavoidable to cause runout.

SUMMARY OF THE INVENTION An object of the present invention is to position a balancer mounted on a rotary shaft in an electric motor in which a load is brought into contact with an outer ring of a bearing mounted on an eccentric shaft provided at the tip of the rotary shaft to linearly drive the load. Is performed accurately and easily.

[0008]

According to the present invention, there is provided an electric motor having an eccentric shaft portion having a center axis at a position radially eccentric with respect to a rotation center axis of the rotation shaft at a tip of the rotation shaft. A bearing having an outer ring concentrically surrounding the eccentric shaft and a rolling element disposed inside the outer ring is attached to the eccentric shaft. The portion adjacent to the eccentric shaft portion of the rotating shaft has a shape symmetrical with respect to a plane including the center axis of rotation of the rotating shaft and one straight line extending in the eccentric direction of the eccentric shaft portion along the radial direction of the rotating shaft. A balancer formed and having a cylindrical outer peripheral surface is fitted. The balancer is formed to have a center of gravity at a position eccentric to a side opposite to an eccentric direction of the eccentric shaft portion with respect to a rotation center axis. The outer ring of the bearing is provided so as to be linearly displaced in the radial direction of the rotating shaft, and a load urged toward the rotating shaft is brought into contact with the outer ring, and the load is applied to the bearing as the rotating shaft rotates. , And reciprocating linear drive.

In the present invention, when the balancer is fitted to the rotating shaft, the position of the center of gravity of the balancer can be correctly positioned at a position eccentric to the side opposite to the eccentric direction of the eccentric shaft with respect to the center axis of rotation. To achieve this, a positioning portion is formed on the outer peripheral portion of the balancer.

[0010] The positioning portion may be a notch provided on the outer peripheral portion of the balancer in a position opposite to the eccentric direction of the center of gravity of the balancer.

The above-mentioned positioning portion may be a cut surface provided on an outer peripheral portion of the balancer in a state where the positioning portion is located at a position opposite to the eccentric direction of the center of gravity of the balancer.
This cut surface is provided so as to be orthogonal to the eccentric direction of the center of gravity of the balancer.

The positioning portion may be a pair of cut surfaces provided on the outer peripheral portion of the balancer in a state parallel to the eccentric direction of the center of gravity of the balancer and opposed to the direction perpendicular to the eccentric direction of the center of gravity. it can.

When the balancer is mounted on the rotating shaft, the balancer is repaired in a state where the notch or cut surface of the balancer is engaged or abutted on a balancer positioning portion provided on a jig for holding the balancer. The balancer is fitted to the rotating shaft by pressing the rotating shaft with the eccentric direction of the eccentric shaft part, to which the bearing is fitted, being positioned by the jig into the inner periphery of the positioned balancer. I do.

As described above, if a notch or a cut surface for positioning is provided on the outer peripheral portion of the balancer so as to have a predetermined positional relationship with respect to the position of the center of gravity of the balancer, the balancer can be used when machining the balancer. When the is mounted on the rotating shaft of the electric motor, the eccentric direction of the center of gravity of the balancer with respect to the rotation center axis can be accurately positioned with reference to the cutout portion or cut surface of the balancer. Accordingly, the eccentric load generated in the radial direction of the rotating shaft by the eccentric shaft portion and the bearing can be accurately canceled by the balancer, and the electric motor having no rotation of the rotating shaft can be obtained.

As described above, if a notch or a cut surface having a predetermined positional relationship with respect to the position of the center of gravity of the balancer is provided on the outer peripheral portion of the balancer, a jig is provided on the cut surface or the notch. Can be automatically positioned at a predetermined position by engaging or abutting the balancer, the work of attaching the balancer can be facilitated, and the work of attaching the balancer can be easily automated. be able to.

[0016]

1 (A) to 1 (C) show the structure of a motor according to the present invention. In FIG. An eccentric shaft portion 2a having a center axis O2 is formed at a position radially eccentric (amount of eccentricity d) with respect to the rotation center axis O1 of the rotary shaft, and a load (not shown) is reciprocally driven linearly in the eccentric shaft portion in the radial direction. Bearing 3 is mounted. A portion of the rotating shaft 2 on the side of the electric motor body 1 adjacent to the eccentric shaft portion 2a is formed with a balancer fitting shaft portion 2b having a diameter larger than that of the eccentric shaft portion 2a and having the rotation center axis O1 as a center axis. The balancer 4 is fitted to the balancer fitting shaft by press fitting. The portion of the rotating shaft 2 on the shaft end side adjacent to the eccentric shaft portion 2a has a smaller diameter than the eccentric shaft portion 2a and has a rotation center axis O.
A retainer fitting shaft portion 2c having a central axis 1 is formed,
An annular retainer 5 for press-fitting the retainer fitting shaft portion to prevent the bearing 3 from coming off in the axial end direction. The balancer 4 and the retainer 5 are attached with a small gap in the axial direction between the balancer 4 and the bearing 3.

The motor body 1 includes an armature 6 and a commutator 7 fixed to the rotating shaft 2, a permanent magnet field 9 fixed to the inner circumference of a peripheral wall of a yoke 8 formed substantially in a cup shape, and a front side. A brush assembly 11 and an input terminal assembly 12 attached to the cover 10 are provided. Both ends of the rotating shaft 2 are respectively connected to a central portion of the bottom wall of the yoke 8 by a rear motor bearing 13 and a front motor bearing 14. It is supported at the center of the front cover 10.

In the illustrated example, the bearing 3 is formed of a needle bearing, an outer ring 3a concentrically surrounding the eccentric shaft portion 2a, and a rolling element (a plurality of needles held by a retainer) 3b disposed inside the outer ring. And

As shown in FIGS. 1B and 2, the balancer 4 has a plane including a rotation center axis O 1 and one straight line extending in the eccentric direction of the eccentric shaft portion 2 a along the radial direction of the rotation shaft 2. (YY plane in FIG. 2). The inner peripheral surface 4a of the balancer 4 is formed so as to exhibit a cylindrical surface shape having the rotation center axis O1 as the center axis.
The outer peripheral surface 4b is formed with an eccentric shaft portion 2a with respect to the rotation center axis O1.
Is formed so as to have a cylindrical surface shape having a central axis O3 at a position eccentric to the opposite side of the eccentric direction. The center of gravity G of the balancer 4 is located at a position eccentric with respect to the rotation center axis O1 in the same direction as the center axis O3, and is generated in the radial direction of the rotation shaft 2 by the balancer 4 when the rotation shaft 2 is rotating. The weight of the balancer 4 and the magnitude of the amount of eccentricity at the position of the center of gravity G are selected so that the magnitude of the eccentric load is equal to the magnitude of the radial eccentric load generated by the eccentric shaft portion 2a and the bearing 3. .

The balancer 4 used in the illustrated example is used for positioning the balancer by engaging with a jig when processing the balancer or attaching the balancer to the balancer fitting shaft portion 2b of the rotating shaft. An arc-shaped notch 4c is formed in the outer periphery of the balancer 4 in a state opposite to the direction of eccentricity of the center of gravity of the balancer 4.

The balancer 4 is made of, for example, a sintered alloy. The central axis O1 of the inner peripheral surface 4a, the central axis O3 of the outer peripheral surface 4b, and the central axis of the arc surface of the notch 4c are in the same plane (A plane). ) Is formed as above. When the inner peripheral surface 4a of the balancer needs to be finished, a notch 4c is provided on a positioning portion (notch 4c) provided on the jig.
The inner peripheral surface 4a is finished in a state where the inner peripheral surface 4a is engaged with the protrusions.

The balancer 4 is connected to the balancer fitting shaft portion 2 of the rotating shaft.
b, the notch 4 of the balancer is formed in the balancer positioning projection provided on the jig for holding the balancer.
The balancer is held by the jig in a state where c is engaged. Further, the jig is provided with a guide hole for positioning the rotary shaft 2 in the rotation direction by fitting the eccentric shaft portion 2a and the retainer fitting shaft portion 2c of the rotary shaft 2, respectively. With the shaft portion 2a and the retainer fitting shaft portion 2c fitted, the balancer fitting shaft portion 2b is press-fitted into the balancer 4 and the balancer is fitted to the balancer fitting shaft portion 2b of the rotating shaft.

FIG. 3 shows a different configuration example of a balancer having a notch for positioning formed on the outer peripheral portion.
In the example shown in FIG. 3, the inner peripheral surface 4a and the outer peripheral surface 4b of the balancer 4 are formed to have a cylindrical surface shape sharing the rotation axis 2 and the rotation center axis O1. In this example, when the balancer 4 is fitted to the balancer fitting shaft 2b, the eccentric shaft 2a with respect to the rotation center axis O1 of the rotating shaft 2 is fitted.
Is cut out over a half circumference to form a notch 4c having a semi-cylindrical positioning surface 4c1 having the rotation center axis O1 as the center axis. I have. The radius of the inner peripheral surface 4a of the balancer 4 is R1
Assuming that the radius of the outer peripheral surface 4b is R2 and the radius of the positioning surface 4c1 of the notch 4c is R3,
There is a relationship of R1 <R3 <R2.

At the boundary between the outer peripheral surface 4b of the balancer 4 and both ends of the positioning surface 4c1 of the notch 4c, the rotation center axis O
Positioning surfaces 4c2, 4c2 are formed, which are planes orthogonal to the YY plane including 1 and the central axis O2 of the eccentric shaft. The balancer 4 is formed in a shape symmetric with respect to the YY plane, and the center of gravity G of the balancer 4 is
The eccentric shaft is eccentric to the side opposite to the eccentric direction.

When attaching the balancer 4 shown in FIG. 3 to the balancer fitting shaft portion 2b of the rotating shaft, the balancer fitting is performed with the notch portion 4c of the balancer engaged with the balancer positioning portion of the jig and positioned. The spindle 2b is press-fitted into the balancer 4.

FIG. 4 shows an example of the configuration of a balancer in which a cut surface is formed on the outer peripheral portion and the cut surface is used as a positioning portion. In the balancer 4 shown in FIG. 4, portions other than the positioning portion are formed in the same shape as the balancer shown in FIG. In the example shown in FIG. 4, the outer peripheral portion of the balancer 4 is positioned on the opposite side to the eccentric direction of the center of gravity G of the balancer 4 with respect to the rotation center axis O 1 of the rotating shaft. An orthogonal cut surface 4d is formed, and this cut surface 4d is used as a positioning portion.

When attaching the balancer 4 shown in FIG. 4 to the balancer fitting shaft portion 2b of the rotating shaft, the cut surface 4d of the balancer is brought into contact with the balancer positioning portion of the jig, and the balancer is attached to the jig. The balancer fitting shaft 2b is pressed into the balancer 4 with the positioning and holding.

FIG. 5 shows another configuration example of a balancer in which a cut surface is formed on the outer peripheral portion and the cut surface is used as a positioning portion. In this example, the center of gravity G of the balancer is provided on the outer peripheral portion of the balancer 4. The pair of cut surfaces 4d, 4d, which are parallel to the eccentric direction, are formed so as to face in a direction perpendicular to the eccentric direction of the center of gravity G. The shape of the portion other than the positioning portion of the balancer 4 is the same as that of the balancer shown in FIGS.

When the balancer 4 shown in FIG. 5 is mounted on the balancer fitting shaft portion 2b of the rotating shaft, the cut surfaces 4d, 4d of the pair of balancers are brought into contact with the balancer positioning portion of the jig. Then, the balancer is positioned and held on the jig, and the balancer fitting shaft 2b is pressed into the balancer 4.

Also in the balancer 4 shown in FIGS. 3 to 5, the center of gravity G of the balancer with respect to the rotation center axis O1.
Of the eccentricity and the weight of the balancer, the magnitude of the eccentric load generated in the radial direction of the rotating shaft by the balancer when the rotating shaft 2 is rotating cancels out the eccentric load generated by the eccentric shaft portion 2a and the bearing 3. The size is selected. In each of the above examples, a needled bearing is used as the bearing 3. However, the bearing 3 is a radial type rolling bearing including an outer ring and rolling elements such as rollers and balls disposed inside the outer ring. I just need.

In each of the above examples, the retainer fitting shaft portion 2c of the rotary shaft on which the retainer 5 is fitted is formed so that the center axis is the rotation center axis O1 of the rotary shaft. The mounting shaft 2c may be formed so that the center axis O2 of the eccentric shaft 2a to which the bearing 3 is fitted is set as the center axis. In this case, the magnitude of the eccentric load in the radial direction generated when the rotating shaft is rotated by the balancer 4 depends on the bearing 3.
The weight of the balancer 4 and the eccentric position of the center of gravity G are selected so as to offset the radial eccentric load generated by the eccentric shaft 2a, the retainer 5 and the retainer fitting shaft 2c.

[0032]

As described above, in the present invention, since the positioning portion formed of the notch or the cut surface is formed on the outer peripheral portion of the balancer, the positioning of the balancer is performed with reference to the notch or the cut surface. Can be accurately determined. Therefore, the balancer can be attached to the rotating shaft with high accuracy, the unbalanced load generated in the radial direction of the rotating shaft can be eliminated, and an electric motor having no rotation of the rotating shaft can be obtained.

According to the present invention, the balancer can be positioned by engaging or abutting a jig for positioning the balancer with the notch or the cut surface, so that the balancer can be positioned. Can be easily attached, and the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 shows a configuration example of an electric motor according to the present invention, in which (A) is a longitudinal sectional view, (B) is a sectional view taken along line BB of (A), and (C) is C of (A). FIG. 4 is a sectional view taken along line C of FIG.

FIG. 2 is a front view of a balancer used in the electric motor of FIG.

FIG. 3 is a front view showing another configuration example of a balancer that can be used in the present invention.

FIG. 4 is a front view showing still another configuration example of a balancer that can be used in the present invention.

FIG. 5 is a front view showing still another configuration example of the balancer that can be used in the present invention.

FIG. 6 shows a configuration of a main part of a conventional electric motor.
(A) is a longitudinal sectional view near the tip of the rotating shaft, (B) is a sectional view taken along line BB of (A), and (C) is a sectional view taken along line CC of (A).

FIG. 7 is a front view of a balancer used in the electric motor of FIG. 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Motor main body 2 Rotating shaft 2a Eccentric shaft part 2b Balancer fitting shaft part 2c Retainer fitting shaft part 3 Bearing 3a Outer ring 3b Rolling element 4 Balancer 4a Inner peripheral surface 4b Outer peripheral surface 4c Notch portion 4d Cut surface 5 Retainer 6 Armature 7 Commutator 8 Yoke 9 Permanent magnet 10 Front cover 11 Brush assembly 12 Input terminal assembly 13 Motor bearing 14 Motor bearing

Claims (3)

[Claims] An eccentric shaft portion having a center axis at a position radially eccentric with respect to a rotation center axis of the rotation shaft is formed at a tip of the rotation shaft, and the eccentric shaft portion includes A bearing comprising an outer ring concentrically surrounding the outer ring and a rolling element disposed inside the outer ring is attached, and an eccentric direction of the eccentric shaft portion along a rotation center axis of the rotation shaft and a radial direction of the rotation shaft. A balancer that is formed in a shape symmetrical with respect to a plane including one straight line extending toward the eccentric shaft and has a cylindrical outer peripheral surface is fitted to a portion of the rotary shaft adjacent to the eccentric shaft portion; Is formed so as to have a center of gravity at a position eccentric to the side opposite to the eccentric direction of the eccentric shaft portion with respect to the rotation center axis, and is provided so as to be linearly displaced in a radial direction of the rotation shaft and the rotation is provided. Apply the load urged to the shaft side to the outer ring. A motor that linearly drives the load in a reciprocating manner with the rotation of the rotating shaft, wherein a notch is formed in an outer peripheral portion of the balancer in a state opposite to an eccentric direction of the center of gravity of the balancer. An electric motor characterized in that a part is formed. 2. An eccentric shaft portion having a center axis at a position radially eccentric with respect to a rotation center axis of the rotating shaft is formed at a tip of the rotating shaft, and the eccentric shaft portion includes A bearing comprising an outer ring concentrically surrounding the outer ring and a rolling element disposed inside the outer ring is attached, and an eccentric direction of the eccentric shaft portion along a rotation center axis of the rotation shaft and a radial direction of the rotation shaft. A balancer that is formed in a shape symmetrical with respect to a plane including one straight line extending toward the eccentric shaft and has a cylindrical outer peripheral surface is fitted to a portion of the rotary shaft adjacent to the eccentric shaft portion; Is formed so as to have a center of gravity at a position eccentric to the side opposite to the eccentric direction of the eccentric shaft portion with respect to the rotation center axis, and is provided so as to be linearly displaced in a radial direction of the rotation shaft and the rotation is provided. Apply the load urged to the shaft side to the outer ring. And a linear motor that reciprocates the load in accordance with the rotation of the rotating shaft, wherein the center of gravity is located on the outer peripheral portion of the balancer in a state opposite to the eccentric direction of the center of gravity of the balancer. An electric motor characterized in that a cut surface orthogonal to the eccentric direction is formed. 3. An eccentric shaft portion having a center axis at a position radially eccentric with respect to a rotation center axis of the rotation shaft is formed at a tip of the rotation shaft, and the eccentric shaft portion includes an eccentric shaft portion. A bearing comprising an outer ring concentrically surrounding the outer ring and a rolling element disposed inside the outer ring is attached, and an eccentric direction of the eccentric shaft portion along a rotation center axis of the rotation shaft and a radial direction of the rotation shaft. A balancer that is formed in a shape symmetrical with respect to a plane including one straight line extending toward the eccentric shaft and has a cylindrical outer peripheral surface is fitted to a portion of the rotary shaft adjacent to the eccentric shaft portion; Is formed so as to have a center of gravity at a position eccentric to the side opposite to the eccentric direction of the eccentric shaft portion with respect to the rotation center axis, and is provided so as to be linearly displaced in a radial direction of the rotation shaft and the rotation is provided. Apply the load urged to the shaft side to the outer ring. And a linear cut-off surface parallel to the eccentric direction of the center of gravity of the balancer is provided on an outer peripheral portion of the balancer, the eccentricity of the center of gravity of the electric motor. An electric motor characterized by being formed so as to face in a direction perpendicular to the direction.