JP2021173293A - Shaft, motor with reduction gear and method for manufacturing shaft - Google Patents

Abstract

To provide a shaft that can improve efficiency of manufacturing process by preventing a shaft material from shaking at the time of rolling processing, and to provide a motor with a reduction gear and a method for manufacturing a shaft.SOLUTION: A shaft 100 includes a first part L1 that includes: an effective tooth part 51 engaging a worm wheel; a small diameter part 52 disposed in at least one of the directions of a rotation axel of the effective tooth part 51 and not engaging the worm wheel; and an incomplete part 53 formed between the effective tooth part 51 and the small diameter part 52 and having a diameter that is smaller than a diameter of the effective tooth part 51.SELECTED DRAWING: Figure 7

Description

The present invention relates to a shaft, a motor with a speed reducer, and a method for manufacturing the shaft.

For example, a brushless motor has a gap between a rotating shaft, a rotor having a permanent magnet integrated with the rotating shaft and having magnetic poles of opposite polarities alternately arranged along the circumferential direction of the outer peripheral portion, and an outer peripheral portion of the rotor. It also comprises a tubular stator having a coil that produces a rotating magnetic field that rotates the rotor.

For example, a worm gear reducer is connected to the rotating shaft of the brushless motor. The worm gear reducer is housed in the gear housing. The worm gear reducer has a worm provided coaxially and integrally with the rotation shaft of the brushless motor, and a worm wheel that meshes with the worm.
The rotation axis of the worm wheel meshed with the worm is in the direction orthogonal to the rotation axis of the brushless motor. The worm wheel is provided with an output shaft that is orthogonal to the rotation axis of the brushless motor. Then, in the brushless motor, various electrical components (power windows, sunroofs, electric seats, etc.) can be driven by rotating the output shaft of the worm gear reducer via the rotating shaft.

International Publication No. 2017/002869

By the way, in the worm gear reducer shown in the above-mentioned prior art, a worm is provided at one end of a rotating shaft so as to be integrated with the rotating shaft.
The worm has, for example, a tooth portion that has been subjected to so-called rolling or cutting, in which the shaft material is plastically deformed by the rotational contact of the die.

For example, when the worm is formed by rolling, the pushing resistance of the die with respect to the shaft material becomes non-uniform, and the shaft material may swing with respect to the central shaft. As a result, during the rolling process of the worm, additional work such as runout correction of the shaft material is required, which may result in inefficiency in the manufacturing process.

Therefore, the present invention provides a shaft, a motor with a speed reducer, and a method for manufacturing a shaft, which can improve the efficiency of the manufacturing process by suppressing the shaking of the shaft material during rolling.

In order to solve the above problems, in the shaft according to the present invention, the first portion that is the rolling process portion and the second portion that is the shaft body portion that is not rolled are aligned and integrated on the same axis. The first portion is a shaft that is meshed with a gear, and the first portion is arranged at least one of an effective tooth portion that is meshed with the gear and the effective tooth portion in the axial direction. It is characterized by having a small diameter portion that does not mesh with the gear and an incomplete portion formed between the effective tooth portion and the small diameter portion and having a diameter smaller than the diameter of the effective tooth portion.

In the above configuration, the first portion may be a worm and the second portion may be a motor shaft.

In the above configuration, the incomplete portion may have a tapered shape in which the diameter gradually decreases from the effective tooth portion toward the small diameter portion.

In the above configuration, the incomplete portion may be a step formed between the effective tooth portion and the small diameter portion.

In the above configuration, the minimum diameter of the incomplete portion may be the same as the tooth bottom diameter of the effective tooth portion.

The motor with a speed reducer according to the present invention includes the shaft described above, a motor that rotationally drives the shaft main body portion of the second portion of the shaft, and a worm wheel that is meshed with the first portion of the shaft. It is characterized by including a speed reducer having a speed reducer.

In the method for manufacturing a shaft according to the present invention, by cutting the shaft material before rolling, an effective tooth portion in which a gear is meshed and a small diameter portion in which the gear is not meshed are formed in the rolling processing portion. It is characterized by having a step of forming an incomplete portion separating the region of the effective tooth portion and the region of the small diameter portion, and a step of plastically deforming the region of the effective tooth portion by rolling.

According to the present invention, when an effective tooth portion such as a worm is formed by rolling, additional work such as runout correction of a shaft material becomes unnecessary, and the manufacturing process can be made more efficient.

A partially disassembled perspective view showing a motor with a speed reducer to which the brushless motor according to the embodiment of the present invention is applied. FIG. 5 is a cross-sectional view showing a motor with a speed reducer to which the brushless motor according to the embodiment of the present invention is applied. It is explanatory drawing which shows the relationship between the shaft and the worm wheel which concerns on embodiment of this invention, (A) shows the state which the shaft is meshed with a worm wheel, (B) is the shaft shown as a comparative example is a worm wheel. Indicates a state of being meshed with. It is a side view of the shaft which concerns on embodiment of the invention, (A) shows the blank of the shaft used at the time of manufacturing, (B) shows how the blank of (A) is rolled by a die. The side view of the shaft which concerns on embodiment of the invention. The graph which shows the relationship between the inclination angle of an incomplete part and worm runout which concerns on embodiment of an invention. It is explanatory drawing for stepwise explaining the manufacturing method of the shaft which concerns on embodiment of an invention, and (A)-(C) show each process.

Next, an embodiment of the present invention will be described with reference to the drawings.

<Motor with reducer>
FIG. 1 is a partially exploded perspective view of a motor 1 with a speed reducer to which the shaft 100 according to the present invention is applied. FIG. 2 is a cross-sectional view of the motor 1 with a speed reducer.
The motor 1 with a speed reducer serves as a drive source for electrical components (for example, a power window, a sunroof, an electric seat, etc.) mounted on a vehicle or the like.
As shown in FIGS. 1 and 2, in the motor 1 with a speed reducer, the shaft 100 according to the present invention is used as the rotation shaft of the brushless motor 2. A worm gear reducer 3 is installed on the other end side of the shaft 100 of the brushless motor 2.

<Brushless motor>
The brushless motor 2 includes a shaft 100, a cylindrical stator 10 arranged concentrically with respect to the shaft 100, and a rotor 4 integrated with the shaft 100 and arranged on the inner peripheral side of the stator 10 via a gap. It is an inner rotor type brushless motor equipped with. In the following description, the rotation axis O of the brushless motor 2 (the rotation axis of the rotor 4 described later, an example of the axis in the claim) is referred to as an axial direction, and the rotation direction of the rotor 4 is referred to as a circumferential direction. The direction orthogonal to the circumferential direction is called the radial direction.

<Stator>
The stator 10 includes a stator housing 11 that forms an outer shell, a stator core 12 that is arranged inside the stator housing 11, and a coil 13 that is wound around the stator core 12.

<Stator housing>
The stator housing 11 is formed of, for example, a metal material in a bottomed cylinder having a substantially rounded regular hexagonal cross section that is orthogonal to the axial direction. Inside the stator housing 11, a stator core 12 having a plurality of coils 13 formed therein is fixedly arranged along the circumferential direction by fixing means such as adhesion or press fitting.

<Stator core>
The stator core 12 is formed in a square cylinder having a substantially rounded regular hexagonal cross section that is orthogonal to the axial direction and can be press-fitted into the stator housing 11 (see FIG. 2). The stator core 12 has a ring yoke portion 14 formed in a square cylinder having a substantially rounded regular hexagonal cross section, and a plurality of stator cores 12 projecting inward in the radial direction of the ring yoke portion 14 (six in this embodiment). It has a teeth portion 15 of the above. In the stator core 12, a plurality of the above-mentioned coils 13 (for example, six in the present embodiment) are formed by winding a winding around the teeth portion 15 via a resin insulator (not shown).

The coils 13 of each phase generate a rotating magnetic field for rotating the rotor 4 by supplying power from an external power source.
As shown in FIG. 2, a bearing housing 16 is projected from the bottom of the stator housing 11. The bearing housing 16 is internally fitted with a bearing 17 for rotatably supporting one end of the shaft 100.

<Rotor>
The rotor 4 includes a shaft 100, a cylindrical rotor core 5 press-fitted to the outer periphery of the shaft body 50 (see FIG. 5) of the shaft 100, and a plurality of segment-type permanent magnets provided on the outer periphery of the rotor core 5. It has a magnet (rotor magnet) 6 and a magnet cover 7 made of a non-magnetic material (made of stainless steel or the like) fitted to the outer periphery of the permanent magnet 6. The central axis of the shaft 100 coincides with the axial direction. The magnet cover 7 has a role of holding the permanent magnet 6 at a desired position on the outer circumference of the rotor core 5, and also has a role of preventing dust from adhering to or damaging the permanent magnet 6.

<Permanent magnet>
The permanent magnet 6 is formed of, for example, a ferrite magnet. The permanent magnet 6 is formed in a shape in which a cross section orthogonal to the axial direction is fan-shaped. The permanent magnets 6 are arranged at equal intervals so that the magnetic poles on the outer peripheral surface thereof are alternately arranged in the circumferential direction with opposite polarities. The magnet cover 7 is fitted on the outer periphery of the permanent magnets 6 arranged in the circumferential direction. The shaft 100, the rotor core 5, the permanent magnet 6 and the magnet cover 7 are integrally formed, and the rotating magnetic field of the coil 13 acts on the permanent magnet 6 to rotate the rotor 4 integrated with the shaft 100.

<Worm gear reducer>
As shown in FIG. 2, in addition to the gear housing 20, the worm gear reducer 3 includes a worm 21 housed in the gear housing 20 and a worm wheel meshed with the worm 21 (an example of a gear in the claim). 22 and.
The gear housing 20 is formed with a storage space 23 for accommodating the worm 21 and the worm wheel 22. The other end of the shaft 100 is inserted into the accommodation space 23 of the gear housing 20 while being supported by the bearing 25 in the bearing housing 24. The worm 21 is provided on the other end side of the shaft 100 so as to rotate integrally.

The worm wheel 22 meshed with the worm 21 is provided with an output shaft 101 along a direction orthogonal to the shaft 100 (axial direction) of the brushless motor 2. Then, when the output shaft 101 rotates, various electrical components (power windows, sunroofs, electric seats, etc.) are driven.

<Sensor board>
Inside the connection portion of the gear housing 20 to the brushless motor 2, that is, inside the connection portion between the stator housing 11 and the gear housing 20, a sensor substrate as a rotation detection means for detecting the rotation angle position of the shaft 100 (rotor 4). 30 is provided. The sensor substrate 30 is arranged around the shaft 100 at a position adjacent to the rotor 4 in the axial direction. Further, what is indicated by reference numeral 31 in FIG. 2 is an external connection connector for supplying a current to the coil 13.

<Shaft>
3A and 3B are explanatory views showing the relationship between the shaft and the worm wheel 22, FIG. 3A shows a state in which the shaft 100 is meshed with the worm wheel 22, and FIG. 3B shows a state in which the shaft shown as a comparative example is a worm wheel. It shows the state of being meshed with 22.
As shown in FIG. 3A, the shaft 100 includes a first portion L1 which is a rolling processed portion to be rolled and a second portion L2 which is a shaft main body 50 which is not rolled. Are lined up and integrated on the same rotation axis O.
In the shaft 100, the first portion L1 is the worm 21, and the second portion L2 constitutes the shaft main body portion 50 of the motor shaft located in the brushless motor 2. Further, the shaft 200 as a comparative example of FIG. 3B does not have an incomplete portion (described later) in a tapered shape.

4A and 4B are side views of the shaft 100. FIG. 4A shows a blank (shaft material) 100'of the shaft 100 used at the time of manufacturing, and FIG. 4B shows a blank 100'of (A) rolled by a die D. Shows how it is processed. FIG. 5 is a side view of a finished product of the shaft 100 manufactured from the blank 100'.
As shown in FIG. 4A, the first portion L1 has an effective tooth portion 51 forming the tooth portion of the worm 21 and a small diameter portion 52 arranged on both sides of the effective tooth portion 51 in the axial direction. There is. The effective tooth portion 51 is a portion that meshes with the worm wheel 22. The small diameter portion 52 is a portion where the tooth shape is incomplete and does not mesh with the worm wheel 22.

An incomplete portion 53 having a diameter smaller than the diameter of the effective tooth portion 51 is formed between the effective tooth portion 51 and the small diameter portion 52. The incomplete portion 53 is formed in a tapered shape in which the diameter gradually decreases from the effective tooth portion 51 toward the small diameter portion 52. The incomplete portion 53 is formed so that its minimum diameter portion 54 (minimum diameter and diameter are indicated by reference numerals d) is the same as the tooth bottom diameter of the effective tooth portion 51.

Then, as shown in FIG. 4B, in the blank 100', the incomplete portion 53 located between the effective tooth portion 51 and the small diameter portion 52 of the first portion L1 is rolled into the die D. By pressing from the outside (the pressing direction is indicated by reference numerals P1 and P2) by pushing in, the machining load by the die D can be relatively increased as well as the contact area between the die D and the shaft material. As a result, in the shaft 100, the runout of the shaft material during the rolling process can be suppressed. Further, when the effective tooth portion 51 to be the worm 21 is rolled, additional work such as runout correction of the shaft material becomes unnecessary, and the manufacturing process becomes efficient.

The inclination of the incomplete portion 53 forming the taper is preferably set to about 5 to 30 ° with respect to the rotation axis O.

FIG. 6 is a graph showing changes in worm runout when the vertical axis is the worm runout (μm) and the horizontal axis is the inclination angle (°) of the incomplete portion 53.
As shown in FIG. 6, when the inclination of the incomplete portion 53 is set to 5 to 30 ° (indicated by the measured values a1 and a2), it is compared with a blank having no inclination (indicated by the measured value a0). It can be confirmed that the runout of the shaft material when the worm 21 is rolled is greatly reduced.

<Shaft manufacturing method>
Next, a method for manufacturing the shaft 100 will be described in detail with reference to FIG. 7.
7A and 7B are explanatory views for stepwise explaining the manufacturing method of the shaft 100, and FIGS. 7A to 7C show each step.

<Cutting process>
First, a blank 100'with the same diameter as shown in FIG. 7A is prepared, and the end portion of the blank 100'is chamfered by cutting in order to press-fit the rotor core 5 of the brushless motor 2.
Next, as shown in FIG. 7B, the outer shapes of the effective tooth portion 51 and the small diameter portion 52 are formed by cutting at the first portion L1 which is the rolling processed portion of the blank 100', and these regions are formed. The incomplete portion 53 that separates is formed.

<Rolling process>
Next, the worm 21 as shown in FIG. 7C is created by performing a process of plastically deforming the region of the effective tooth portion 51 by rolling with the die D. At this time, by pressing the incomplete portion 53 located between the effective tooth portion 51 and the small diameter portion 52 of the first portion L1 by pushing the die D, it is possible to suppress the vibration of the shaft body and the generation of noise. ..

As described above, in the shaft 100 of the above-described embodiment, at the time of manufacturing, the incomplete portion 53 located between the effective tooth portion 51 and the small diameter portion 52 of the first portion L1 is rolled on the die D. By pressing from the outside by pushing, the machining load by the die D can be relatively increased as well as the contact area between the die D and the shaft body. As a result, it is possible to suppress the runout of the shaft material during the rolling process.
As a result, in the present embodiment, when rolling the effective tooth portion 51 such as the worm 21 is performed, additional work such as runout correction of the shaft body becomes unnecessary, and the manufacturing process can be made more efficient.

Further, in the shaft 100, the incomplete portion has a tapered shape in which the outer diameter gradually decreases from the effective tooth portion 51 toward the small diameter portion 52. Therefore, the die D that is rolled by the incomplete portion 53 can be stably pressed from the outside, and the runout of the shaft material during the rolling can be reliably prevented.

Further, in the shaft 100, by making the minimum diameter portion 54 of the incomplete portion 53 the same as the tooth bottom diameter of the effective tooth portion 51, for example, the taper of the incomplete portion 53 can be made a gently inclined surface. Therefore, the shaft material can be supported on the die D without causing play.

In the shaft 100, the incomplete portion 53 located between the effective tooth portion 51 and the small diameter portion is formed in a tapered shape. However, the present invention is not limited to this, and a step may be formed instead of the incomplete portion 53. By pressing the small diameter portion of the stepped portion with the die D, it is possible to similarly prevent the shaft body from swinging.

Further, in the above-described embodiment, the case where the shaft 100 has incomplete portions 53 formed on both sides of the effective tooth portion 51 has been described. However, the present invention is not limited to this, and may be limited to the shaft body 50 side only. Even with such an incomplete portion 53 at one location, it is possible to prevent the shaft material from swinging by pressing it with the die D.

Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like within a range not deviating from the gist of the present invention are also included.

1 ... Motor with reducer, 2 ... Brushless motor, 3 ... Worm gear reducer, 21 ... Worm, 22 ... Worm wheel (gear), 50 ... Shaft body, 51 ... Effective teeth, 52 ... Small diameter, 53 ... Not Complete part, 54 ... Minimum diameter part, 100 ... Shaft, 100'... Blank, D ... Dice, O ... Rotating axis (axis), L1 ... 1st part, L2 ... 2nd part

Claims (7)

The first part, which is the rolling part, and the second part, which is the shaft body that is not rolled, are integrated side by side on the same axis, and the first part is a shaft that is meshed with a gear. hand,
The first part is
The effective tooth part that meshes with the gear and
A small diameter portion that is arranged in at least one of the effective tooth portions in the axial direction and does not mesh with the gear.
An incomplete portion formed between the effective tooth portion and the small diameter portion and having a diameter smaller than the diameter of the effective tooth portion,
A shaft characterized by having. The first part is warm
The shaft according to claim 1, wherein the second portion is a motor shaft. The shaft according to claim 1 or 2, wherein the incomplete portion has a tapered shape in which the diameter gradually decreases from the effective tooth portion toward the small diameter portion. The shaft according to claim 1 or 2, wherein the incomplete portion is a step formed between the effective tooth portion and the small diameter portion. The shaft according to any one of claims 1 to 4, wherein the minimum diameter of the incomplete portion is the same as the tooth bottom diameter of the effective tooth portion. The shaft according to any one of claims 1 to 5.
A motor that rotationally drives the shaft body of the second portion of the shaft, and
A speed reducer having a worm wheel meshed with the first portion of the shaft,
A motor with a speed reducer, which is characterized by being equipped with. By cutting the shaft material before rolling, an effective tooth portion where the gear is meshed and a small diameter region where the gear does not mesh are formed at the rolling processing portion, and the effective tooth region and the small diameter are formed. The process of forming an incomplete part that separates the area of the part,
The step of plastically deforming the region of the effective tooth portion by rolling and
A method for manufacturing a shaft, which comprises.

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