JP2002369443A - Jointing member for motor, motor for electric power steering and electric power steering apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a joint member for motor which has resistance to changes in the utilization environment and ensures superior strength for impact. SOLUTION: An output shaft inserting hole 2, to which an output shaft is inserted with pressure, is provided to one end side of a jointing member 1 for motor which is provided between the output shaft of motor and a shaft to be driven. Moreover, a hole 3 for inserting the shaft to be driven is provided to the other end side of the jointing member 1 for motor. A spline part 4 is formed to the internal circumferential surface of the hole 3 for engagement with the spline part 4 at the external circumference of the shaft to be driven. The jointing member 1 is formed of a metal mother material through cold forging process. The hole 3 for inserting the shaft to be driven is formed with the projection process using a pin including the spline part. The spline part 4, formed with this process, has hardness which is higher than that of the output shaft inserting hole 2 with hardening through the process.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a joint member for an output shaft of a motor, and more particularly to a technique which is effective when applied to a motor for an electric power steering device.

[0002]

2. Description of the Related Art Generally, a joint member that connects a motor and a gear box or a motor driving device to a motor for transmitting torque of an output shaft of the motor to an input shaft (driven shaft) of the gear box or the like is mounted between the motor and the motor. Have been. Conventionally,
As such a joint member, a type in which two metal boss members attached to the output shaft side and the input shaft side, respectively, are connected is known. Here, a first boss member is press-fitted to a motor output shaft, and a second boss member is attached to an input shaft by an involute spline. Then, the motor and the gear box and the like are connected by press-fitting the boss members of both shafts.

In this case, the second boss member is usually formed to have a higher hardness than the first boss member due to the difference in the fixing method between the output shaft side and the input shaft side. In other words, the output shaft side is often press-fitted and fixed to the boss member after the tip is hardened, while the input shaft side is spline-coupled, so that the input shaft side has a higher hardness than the output shaft side. It is common.

However, in such a joint member, since there is a difference in hardness between the output shaft side and the input shaft side as described above, the connecting portion must be constituted by two parts, and the number of parts increases. There was a problem of doing. In addition, there is a possibility that the coaxiality may be impaired when connecting the two boss members, and there is also a problem that high component precision and processing precision are required to suppress the coaxiality.

Therefore, Japanese Patent Application Laid-Open Nos. 2000-236643 and 200
Japanese Patent Publication No. 1-8402 and the like propose a structure in which such a joint member (connecting member) is integrally formed of a sintered metal material to reduce the number of processing steps and the number of parts. For example, in the motor disclosed in Japanese Patent Application Laid-Open No. 2000-236643, the output shaft side and the input shaft side of the joint member are integrally formed by sintering, and the hardness of the joint member is made different between the output shaft side and the input shaft side to obtain a desired strength. Are constituted by one part. Further, in the motor disclosed in Japanese Patent Application Laid-Open No. 2001-8402, the hardness of the joint member is formed higher than the output shaft or the input shaft,
It is configured so that both can be connected by one part.

[0006]

However, in such a joint member, since different metal materials are sintered on the output shaft side and the input shaft side to form one part, the linear expansion coefficient between the two members is increased. There is a problem that the members may be broken due to a temperature change. That is, there is a difference in the amount of thermal deformation between the output shaft side and the input shaft side, and in particular, at a joint where different materials are mixed, the difference in the amount of deformation is distorted and is added to the member, so that cracks are easily formed. There was a problem. For this reason, when applying the joint member to an automobile part used from a cold region to a tropical region, compatibility with the use environment has been an issue.

In addition, since the sintered metal member is generally vulnerable to impact, there is a problem that the impact may damage the joint member. For example, when the joint member is used for an automobile part such as a motor for an electric power steering device, the member may be chipped due to an impact during traveling, and its improvement has been demanded. Furthermore, since the brittleness is further increased at the joint of different materials, the impact resistance of the member has also been a problem in application to automobile parts.

An object of the present invention is to withstand changes in the use environment,
An object of the present invention is to provide a motor joint member excellent in impact resistance.

[0009]

According to the present invention, there is provided a motor joint member interposed between an output shaft of a motor and a driven shaft driven by the motor, the output shaft having one end attached to the output shaft. A motor joint member including a mounting portion and a driven shaft mounting portion to which the driven shaft is mounted on the other end side, wherein the motor joint member is formed by cold forging a metal base material. It is characterized by being formed.

[0010] According to the present invention, since the joint member is formed by cold forging, a joint member having excellent impact resistance as compared with a sintered product can be constituted by one part. Therefore, the joint can be applied to a part requiring impact resistance, such as an automobile part, and the number of parts can be reduced. Furthermore, since it is not necessary to perform sizing after processing like a sintered product and it is easy to secure accuracy, it is possible to reduce processing man-hours, reduce center misalignment between shafts, and reduce operating noise and vibration. It becomes possible.

In the joint member for a motor, the output shaft mounting portion and the driven shaft mounting portion may be formed under different processing conditions. This makes it possible to make the hardness different between the output shaft mounting portion and the driven shaft mounting portion, and it is possible to provide a hardness difference within one component made of one material. In this case, for example, the driven shaft mounting portion may be formed by extruding a base material by using a pin member having a spline portion or the like.
Thereby, it is possible to make the hardness of the driven shaft mounting portion higher than that of the output shaft mounting portion.

Further, the motor for electric power steering according to the present invention comprises a cylindrical yoke, an output shaft rotatably provided in the yoke, an armature fixed to the output shaft, A joint member interposed between the driven shaft driven by the motor and
An electric power steering motor that supplies a steering assist force to a steering device of a vehicle via the driven shaft, wherein the joint member is formed by cold forging a metal base material, And an output shaft mounting portion to which the output shaft is mounted, and a driven shaft mounting portion to which the driven shaft formed by extruding the base material is mounted on the other end side.

According to the present invention, a joint member having excellent impact resistance as compared with a sintered product can be constituted by one part, and the impact resistance such as a motor for an electric power steering is required. The joint can also be applied to the above, and the number of parts can be reduced. Furthermore, since it is not necessary to perform sizing after processing like a sintered product and it is easy to secure accuracy, it is possible to reduce processing man-hours, reduce center misalignment between shafts, and reduce operating noise and vibration. It becomes possible.

Further, by constituting an electric power steering device using the motor, the shaft connection accuracy of the joint member is high, so that the operation noise and vibration of the motor are reduced, and the motor operation sound during steering and the motor operation noise are reduced. The vibration transmitted to the driver via the steering wheel can be reduced, and the steering feeling can be improved.

[0015]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a perspective view showing a configuration of a motor joint member according to an embodiment of the present invention,
2 is a cross-sectional view of the joint member of FIG. 1, FIG. 3 is an explanatory view showing a processing method thereof, FIG. 4 is a cross-sectional view of a configuration of an electric power steering motor using the joint member of FIG. 1, and FIG. FIG. 4 is an explanatory diagram illustrating a configuration of an electric power steering device using a motor No. 4;

As shown in FIG. 1, a joint member (hereinafter, joint abbreviated) 1 according to the present invention is a shaft joint formed of a metal such as iron or stainless steel in a cylindrical shape.
As shown in FIG. 4, the motor 11 is attached to the tip of the output shaft 12 of the motor 11. An output shaft mounting hole (output shaft mounting portion) 2 to which the output shaft 12 is mounted is formed on one end side (the right end side in FIG. 2) of the joint 1. The output shaft mounting hole 2 is formed to have a slightly smaller diameter than the output shaft 12, and the output shaft 12 is press-fitted therein and fixed.

The other end of the joint 1 has a motor
Accordingly, a driven shaft mounting hole (driven shaft mounting portion) 3 to which the driven shaft 13 to be driven is mounted is formed. The driven shaft mounting hole 3 is formed to have a larger diameter than the output shaft mounting hole 2, and a spline portion 4 having an involute spline is provided on an inner peripheral surface thereof. The spline portion 4 engages with the spline portion 14 of the driven shaft 13 when the driven shaft 13 is inserted into the driven shaft mounting hole 3. Thus, the two shafts 12 and 13 are connected via the joint 1 while being prevented from rotating.

On the other hand, the joint 1 is formed by cold forging a metal base material made of iron or the like. That is, FIG.
As shown in FIG.
2 is installed, and the base material 33 placed in the die 31 is formed by pressing the punch 34 from above the forming pin 32. In this case, an outer peripheral portion of the forming pin 32 is provided with a spline portion 35 on which an involute spline is formed. Then, the base material 33 is formed from above with the forming pin 3.
The driven shaft mounting hole 3 having the spline portion 4 therein is formed by pressing while making contact with the shaft 2.

After forming the outer shape of the joint 1 while forming the driven shaft mounting hole 3 by cold forging, the output shaft mounting hole 2 is formed. In this case, the output shaft mounting hole 2 is
Since the diameter is smaller, first, a pilot hole smaller in diameter than the output shaft mounting hole 2 is formed on the surface opposite to the driven shaft mounting hole 3 by pressing.
Next, the pilot hole is cut and aligned with the driven shaft mounting hole 3 to form the output shaft mounting hole 2. As a result, the two holes 2 and 3 are formed in the joint 1 with good accuracy.

On the other hand, since the driven shaft mounting hole 3 is formed by extrusion cold forging with the forming pin 32 as described above,
The spline portion 4 has a higher hardness than the base material 33 due to work hardening. On the other hand, since the output shaft mounting hole 2 is cut and finished, it is formed with the same hardness as the base material 33. That is, in the joint 1, the driven shaft mounting hole 3 has a higher hardness than the output shaft mounting hole 2, and a difference in hardness between the two holes 2 and 3 can be provided. For this reason, it is possible to form a joint member having holes with different hardnesses in one part, and since the joint member can be made of the same material, the difference in the amount of thermal deformation as in the case where different kinds of metals are mixed. Does not matter. Further, there is no fragile portion such as a joint between different metals.

Further, since the joint 1 is a forged product,
It is possible to obtain a joint member which is excellent in impact resistance as compared with a sintered product and resistant to impact. Therefore, the joint 1 can be applied to an automobile component that needs to cope with a change in the use environment and impact resistance, and the number of components can be reduced. further,
Unlike a sintered product, there is no need to perform sizing after processing, and accuracy can be easily secured. For this reason, the number of processing steps can be reduced, and the misalignment between the two shafts 2 and 3 can be reduced, so that operation noise and vibration can be reduced.

Next, an electric motor using the joint 1 according to the present invention and an electric power steering device using the same will be described. The motor 11 is a device that supplies a steering assist force of the electric power steering device shown in FIG. 5 and is connected to a gear box 42 attached to an end of the column 41.

As shown in FIG. 4, the motor 11 has a configuration in which a plurality of field permanent magnets 16 are arranged in a cylindrical yoke 15 and an armature 17 is rotatably arranged inside the permanent magnets. The armature 17 includes a core 19 having a plurality of slots 18 extending in the axial direction, and a winding 20 wound around the slots 18. The armature 17 is fixed to the output shaft 12, and is rotatable by bearings 21a and 21b. Supported.

A commutator 22 is provided on the left side of the armature 17 in FIG. The commutator 22 is fixed to the output shaft 12, and a brush 23 is in contact with the surface thereof. The brush 23 is held in a brush holder 24. The brush holder 24 is housed in a bracket 25 and is fixed to the bracket 25 with screws 26. The bracket 25 is connected to the yoke 15 by bolts 27.

At the left end of the output shaft 12, as described above,
A joint 1 is attached. In this case, a spline portion 28 is formed on the output shaft 12 and is hardened. As described above, the output shaft mounting hole 2 of the joint 1 has the same hardness as the base material 33, and the quenched output shaft 12 is press-fitted while the spline portion 28 bites into the output shaft mounting hole 2. Is done. On the other hand, the driven shaft 13 is inserted and fixed to the driven shaft mounting hole 3 while the spline portions 4 and 14 are engaged. At this time, the hardness of the spline portion 4 is higher than that of the output shaft mounting hole 2 due to work hardening.
The spline 4 can withstand the torque transmission. Thus, the output shaft 12 and the driven shaft 13 are connected to each other, and the rotation of the armature 17 causes the driven shaft 13
Also rotate.

When the driver operates the steering wheel 43, the motor 11 supplies a steering assist force according to the steering angle, the vehicle running speed, and the like. That is, the rotation of the driven shaft 13 is transmitted to the column 41 after being appropriately reduced in the gear box 42. As a result, the steering force is
And the driver can operate the steering wheel 43 with a small force. The rotation operation of the column 41 is converted to a reciprocating operation of the tie rod 45 in the rack and pinion type steering gear unit 44, and the steered wheels are steered.

In the electric power steering apparatus using the motor 11, the operation noise and vibration of the motor 11 are reduced because the joint accuracy of the joint 1 is high. Therefore, it is possible to reduce the motor operation sound at the time of steering and the vibration transmitted from the motor to the driver via the steering wheel 43, thereby improving the steering feeling.

The present invention is not limited to the above embodiment, and it goes without saying that various changes can be made without departing from the spirit of the present invention. For example, as a method of forming the driven shaft mounting hole 3 by cold forging and causing work hardening, in addition to the extrusion cold forging by the forming pin 32, a pilot hole slightly larger in diameter than the forming pin 32 is first formed. It is also possible to form the spline portion 4 having high hardness by forming and pressing the outer peripheral portion toward the center in a state where the forming pin 32 is accommodated therein. After the output shaft mounting hole 2 is formed by cutting, it is also possible to harden only the driven shaft mounting hole 3.

In the above-described embodiment, an example is shown in which the joint member 1 is applied to a motor for electric power steering. However, the joint member 1 can be applied to a motor for other uses. For example, the joint member 1 of the present invention is also effective for other in-vehicle motors for automobiles.

[0030]

According to the motor joint member of the present invention, the joint member interposed between the output shaft and the driven shaft is formed by cold forging, so that it has a higher impact resistance than a sintered product. The joint member having excellent properties can be constituted by one part. Therefore, the joint can be applied to a part requiring impact resistance, such as an automobile part, and the number of parts can be reduced. further,
Unlike sintering, it is not necessary to size after processing and it is easy to secure accuracy, so it is possible to reduce processing man-hours, reduce misalignment between axes, and reduce operating noise and vibration. It becomes possible.

Further, by forming the output shaft mounting portion and the driven shaft mounting portion of the joint member under different processing conditions, the hardness between the output shaft mounting portion and the driven shaft mounting portion can be made different. It is possible to provide a hardness difference within one component by one material. Further, by forming the driven shaft mounting portion by extruding the base material using a pin having a spline portion or the like, it is possible to make the hardness of the driven shaft mounting portion higher than that of the output shaft mounting portion.

According to the electric power steering motor of the present invention, a joint member for connecting the output shaft and the driven shaft is formed by cold forging a metal base material, and is formed on one end side. Since an output shaft is provided with an output shaft mounting portion to which the output shaft is mounted, and a driven shaft mounting portion formed by extruding a base material on the other end side is used,
A motor can be configured using a one-piece joint member that is more excellent in impact resistance than a sintered product. Therefore, even for a motor that requires impact resistance, such as a motor for an electric power steering, the number of parts can be reduced by applying the joint member. Further, since the joint member does not need to be subjected to sizing after processing as in the case of a sintered product and it is easy to secure the accuracy, the number of processing steps can be reduced, and the misalignment between axes can be reduced, and the operating noise and vibration can be reduced. Can be reduced.

Further, according to the electric power steering apparatus of the present invention, since the electric power steering apparatus is constituted by using the motor, the shaft connecting accuracy of the joint member is high, the operating noise and vibration of the motor are reduced, and the steering is performed. The motor operation noise and vibration at the time can be reduced, and the steering feeling can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of a motor joint member according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the joint member of FIG.

FIG. 3 is an explanatory view showing a method for processing the joint member of FIG. 1;

4 is a cross-sectional view showing a configuration of an electric power steering motor using the joint member of FIG.

FIG. 5 is an explanatory diagram illustrating a configuration of an electric power steering device using the motor of FIG. 4;

[Explanation of symbols]

 Reference Signs List 1 joint member 2 output shaft mounting hole (output shaft mounting portion) 3 driven shaft mounting hole (driven shaft mounting portion) 4 spline portion 11 motor 12 output shaft 13 driven shaft 14 spline portion 15 yoke 16 field permanent magnet 17 armature 18 slot Reference Signs List 19 core 20 winding 21a, 21b bearing 22 commutator 23 brush 24 brush holder 25 bracket 26 screw 27 bolt 28 spline portion 31 die 32 forming pin (pin member) 33 base material 34 punch 35 spline portion 41 column 42 gear box 43 handle 44 Steering gear part 45 Tie rod

Claims (6)

[Claims] An output shaft mounting portion is provided between an output shaft of a motor and a driven shaft driven by the motor, and has an output shaft mounting portion to which the output shaft is mounted at one end, and the driven shaft at the other end. A motor joint member comprising a driven shaft mounting portion to which is attached, wherein the motor joint member is formed by cold forging a metal base material. . 2. The motor joint member according to claim 1, wherein the output shaft mounting portion and the driven shaft mounting portion are formed under different processing conditions. 3. The joint member for a motor according to claim 1, wherein the driven shaft mounting portion is formed by extruding the base material. 4. The motor joint member according to claim 3, wherein the driven shaft mounting portion is extruded using a pin member having a spline portion. 5. A system according to claim 5, wherein said cylindrical yoke, an output shaft rotatably provided in said yoke, an armature fixed to said output shaft, and a driven shaft driven by said motor and said motor. An electric power steering motor that supplies a steering assisting force to a steering device of the vehicle via the driven shaft, wherein the joint member is made of metal. An output shaft mounting portion formed by cold forging a base material and having the output shaft mounted on one end side, and the driven shaft formed by extruding the base material on the other end side is mounted. A motor for an electric power steering, comprising a driven shaft mounting portion. 6. An electric power steering apparatus using the motor according to claim 5.