JP2006103642A - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a direct drive type electric power steering device capable of radiating the heat to be generated from an electric motor, which is coaxially connected with a column shaft, from a fitting part provided in a peripheral part of a motor housing and capable of reducing the number of parts items and simplifying assembling process to reduce costs by unifying or integrally forming the fitting part with the motor housing. <P>SOLUTION: The motor housing 4 is provided with a bracket 5 (fitting part) unified or integrally formed with the motor housing 4 in a peripheral part thereof, and an upper fitting member 51 of a car body 50 and the bracket 5 are engaged with each other to fix the electric power steering device to the car body 50 to support it. With this structure, the heat to be generated form the direct drive type electric motor can be radiated to the car body 50 through the motor housing 4 and the bracket 5. Furthermore, the number of part items can be reduced and assembling process can be simplified by unifying the motor housing 43 with the bracket 5, and the rigidity of the bracket 5 can be improved. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electric power steering apparatus that generates a steering assist torque by an electric motor connected coaxially to a column shaft.

  A torque sensor for detecting steering torque applied by steering of the steering wheel performed by the driver and an electric motor for generating auxiliary torque for assisting the driver's steering are provided. The steering torque detected by the torque sensor Accordingly, an electric power steering apparatus that reduces the burden on the driver by controlling the rotation of the electric motor and generating an auxiliary torque for the electric motor to steer the vehicle has been put into practical use.

  Some electric power steering devices are configured to assist the steering by decelerating the rotation of the electric motor by a reduction mechanism that combines a worm and a worm wheel and transmitting it to the column shaft. A direct drive system has also been proposed in which an electric motor is connected coaxially with the column shaft and the steering is assisted without using a speed reduction mechanism.

  In any of the configurations described above, the electric power steering device includes a bracket that is an attachment member for attachment to the vehicle body, and the electric power steering device is fixed to the vehicle body by attaching the bracket to the vehicle body. Conventionally, the bracket is formed as a single component and attached to the steering device in the assembly process. Therefore, there is a problem that the cost increases due to an increase in the number of parts and a complicated assembly process, and an improvement measure has been demanded.

  Therefore, a column housing made of aluminum alloy that rotatably supports the column shaft inside, a unit housing that houses a reduction mechanism that combines a worm and a worm wheel, and a housing portion that houses a lock device for preventing theft. In addition, an electric power steering device has been proposed in which an impact absorbing member and the like for absorbing an impact at the time of collision are integrally formed and a bracket is integrally formed with a column housing (see Patent Document 1).

By integrally molding the bracket and the column housing, there is an advantage that the rigidity of the bracket can be increased in addition to cost reduction. When the bracket is welded to the column housing, the shape of the column housing may be distorted due to heat generated during the mounting, but this problem can be solved by integrally molding the bracket and the column housing. .
JP 2002-308122 A

  However, in the electric power steering device disclosed in Patent Document 1, a motor housing is connected in a manner that intersects with the column housing, an electric motor is accommodated in the motor housing, and a reduction mechanism that combines a worm and a worm wheel is provided. In the direct drive type electric power steering device in which the electric motor rotation is transmitted to the column shaft and the electric motor is arranged coaxially with the column shaft, the shape of the entire device is different. The same configuration as that of the disclosed electric power steering apparatus cannot be applied to a direct drive type electric power steering apparatus as it is. For this reason, in order to reduce costs by reducing the number of parts and simplifying the assembly process, and in order to increase the rigidity of the mounting member, the mounting member should be adapted to the shape of the direct drive type electric power steering device. It is required to configure.

  On the other hand, in the direct drive type electric power steering device, since the electric motor is connected coaxially with the column shaft, it is difficult to increase the size of the electric motor due to the mounting space, so that sufficient auxiliary torque is generated. Must increase the amount of current flowing through the electric motor. When the amount of current flowing through the electric motor increases, the amount of heat generated by the motor increases, and it is necessary to increase its heat dissipation efficiency.

  The present invention has been made in view of such circumstances, and an object of the present invention is to equip the outer peripheral portion of the motor housing with a mounting portion to the vehicle body projecting in the radial direction and coaxial with the column shaft. The heat generated from the electric motor connected to the vehicle can be dissipated to the vehicle body via the mounting portion, and the mounting portion and the motor housing can be integrated or integrally molded to reduce the number of parts and assemble. An object of the present invention is to provide a direct drive type electric power steering apparatus capable of reducing costs by simplifying the process.

  An electric power steering apparatus according to a first aspect of the present invention includes a column shaft connected to a steering wheel, an electric motor that is coaxially connected to the column shaft at an intermediate portion of the column shaft, assists steering, and the electric motor. In an electric power steering apparatus including a cylindrical motor housing housed therein, an outer peripheral portion of the motor housing is integrally provided with a mounting portion to the vehicle body that protrudes in a radial direction of the outer peripheral portion of the motor housing. It prepares for.

  The electric power steering apparatus according to a second aspect of the invention is characterized in that the mounting portion is integrally formed with the motor housing.

  In the first aspect of the invention, the motor housing is provided with a mounting portion integrated with the outer peripheral portion thereof, and the electric power steering device is fixed to and supported by the vehicle body by engaging the vehicle body side member and the mounting portion. The heat generated from the electric motor accommodated in the motor housing can be radiated to the vehicle body via the motor housing and the mounting portion. Moreover, since the motor housing and the mounting portion are integrated, the number of parts can be reduced and the assembly process can be simplified, and the rigidity of the mounting portion can be increased.

  In the second invention, since the motor housing and the mounting portion are integrally formed, the number of parts can be reduced and the assembly process can be simplified, the rigidity of the mounting portion can be further increased, and the motor housing and the mounting portion can be The process of integrating can be eliminated.

Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof.
(Embodiment 1)
FIG. 1 is a side view showing a configuration of a main part of an electric power steering apparatus according to the present invention. In the figure, 1 is a column shaft, a steering wheel (not shown) is connected to the upper end of the column shaft 1, and an electric motor (not shown) is connected to the middle of the column shaft 1 coaxially with the column shaft 1. . The electric motor is housed in a cylindrical motor housing 4, and a cylindrical sensor housing 3 is continuously attached to the upper end portion of the motor housing 4. A cylindrical column housing 2 is continuously attached to the lower end portion of the motor housing 4, and the column housing 2 supports the column shaft 1 rotatably inside. That is, the sensor housing 3, the motor housing 4, and the column housing 2 are connected in series, and the column shaft 1 is inserted through them.

  The lower end portion of the column shaft 1 protruding from the lower end portion of the column housing 2 is connected to the intermediate shaft 8 via the universal joint 7 so that the rotation of the column shaft 1 can be transmitted. The lower portion of the intermediate shaft 8 is connected to a rack and pinion mechanism (not shown). The rotation due to the steering of the steering wheel is transmitted to the rack and pinion mechanism via the column shaft 1 and the intermediate shaft 8, and is converted into the steering operation of the vehicle by the rack and pinion mechanism.

  The sensor housing 3 contains a torque sensor for detecting a steering torque applied to the column shaft 1 by a rotation operation of the steering wheel, and a voltage corresponding to the steering torque detected by the torque sensor is applied to a control unit (not shown). It is done. The control unit controls the rotation of the electric motor connected coaxially with the column shaft 1 according to the steering torque, the vehicle speed, the acceleration, and the like, and the auxiliary torque assisting the column shaft 1 with the steering by the rotation of the electric motor. Is given. The electric motor is a brushless motor in which a stator is fixed inside the motor housing 4 and a rotor is directly connected to the column shaft 1.

  Two rectangular plate-like brackets 5 and 5 (see FIG. 2) are provided on the outer peripheral portion of the motor housing 4 as attachment portions for attaching the electric power steering device to the vehicle body. 6 is provided. The vehicle body 50 in the vicinity of the driver's seat of the vehicle is provided with an upper mounting member 51 and a lower mounting member 52 for mounting the electric power steering device. The bracket 5 is fixed to the upper mounting member 51, the lower bracket 6 is fixed to the lower mounting member 52, and the electric power steering device is mounted to the vehicle body 50.

  FIG. 2 is a perspective view of the motor housing 4 of the electric power steering apparatus according to Embodiment 1 of the present invention. The brackets 5 and 5 project radially in the outer peripheral portion near the tip of the cylindrical motor housing 4 so as to be substantially parallel to the axial length direction of the motor housing 4 and to face each other. The brackets 5 and 5 are respectively provided with elliptical guide holes 9 and 9 that are long in a direction substantially parallel to the axial length direction of the motor housing 4. The brackets 5 and 5 are sandwiched between upper mounting members 51 of the vehicle body 50, and hexagon bolts 53 are inserted into the guide holes 9 and 9, so that the motor housing 4 is fixed to the vehicle body 50.

  The upper mounting member 51 has a channel shape, and has rectangular holding plates 56 and 56 facing each other at a distance similar to the distance between the outer surfaces of the two brackets 5 and 5 projecting in parallel. It has the connection plate 57 which connects the end parts of the plates 56 and 56. FIG. The upper mounting member 51 is disposed in the vicinity of the driver's seat of the vehicle body 50 so that the connecting plate 57 is on the upper side, and the motor housing 4 is clamped by the clamping plates 56 and 56 so as to sandwich the two brackets 5 and 5. To do. The sandwiching plates 56 and 56 are provided with elliptical mounting holes 55 and 55 that are long in a direction substantially orthogonal to the guide holes 9 and 9 of the brackets 5 and 5, respectively. Hexagonal bolts 53 are inserted into the guide holes 9 and 9 and the mounting holes 55 and 55 of the upper mounting member 51. The tip of the hexagon bolt 53 protrudes from the mounting hole 55, the nut 54 is screwed into the protruding portion, and the brackets 5 and 5 are fixed.

  The motor housing 4 and the brackets 5 and 5 are made of metal such as aluminum or iron, and are integrated by welding. The welding method includes fusion welding such as electron beam welding and high-frequency welding, pressure welding, brazing, or the like, and a welding method most suitable for the material and shape of the motor housing 4 and the brackets 5 and 5 is used. When there is a possibility that the motor housing 4 is distorted by welding the brackets 5 and 5, the inner peripheral surface of the motor housing 4 is ground after welding, so that the performance degradation and assembly of the electric motor housed in the motor housing 4 are reduced. Sexual deterioration can be eliminated.

  In the electric power steering apparatus configured as described above, the heat generated from the electric motor housed in the motor housing 4 is transmitted from the motor housing 4 to the brackets 5 and 5, and the vehicle body via the upper mounting member 51. Heat is released to 50.

  In the present embodiment, the brackets 5 and 5 are rectangular plates. However, the shape is not limited to this, and may be another shape such as a trapezoid or a triangle. Moreover, although it was set as the structure provided with two brackets 5 and 5 in the outer peripheral part of the motor housing 4, it is not restricted to this, It is good also as a structure provided with the bracket 5 one or more.

(Embodiment 2)
FIG. 3 is a perspective view of the motor housing 4 of the electric power steering apparatus according to Embodiment 2 of the present invention. In the first embodiment, the motor housing 4 and the brackets 5 and 5 are welded. However, in the present embodiment, these are integrally formed as a single component. By integrally molding, it is possible to eliminate the step of welding the brackets 5 and 5 to the motor housing 4 and the step of correcting distortion generated in the motor housing 4 by welding by grinding the inner peripheral surface.

  FIG. 4 is a top view of the motor housing 4 of the electric power steering apparatus according to Embodiment 2 of the present invention. (A) is the same as the structure shown in FIG. 3, (b) shows another example of a structure of this Embodiment. In (a), the two brackets 5 and 5 are formed so as to face each other so as to be substantially parallel to the axial length direction of the motor housing 4, but in FIG. The housing 4 is formed so as to be opposed to each other with a certain angle with respect to the axial length direction of the housing 4, and another bracket 5b having the same shape and brackets 5a and 5a of the motor housing 4 are formed. It is configured to be formed at the opposite end of a certain part.

  As shown in FIG. 4B, the brackets 5a and 5a are not formed so as to face each other in parallel, but may be configured to face each other with a certain angle. The angle may be arbitrary. Moreover, although it was set as the structure provided with two brackets 5a and 5a in the motor housing 4, it may be the structure provided with 1 or 3 or more not only in this. In this case, the shape and the number of the upper mounting members 51 provided in the vehicle body 50 are configured to be optimum.

  Since the other configuration of the electric power steering apparatus according to the second embodiment is the same as that of the electric power steering apparatus according to the first embodiment, the same portions are denoted by the same reference numerals and detailed description thereof is omitted. To do.

(Embodiment 3)
FIG. 5 is a perspective view of the motor housing 4 of the electric power steering apparatus according to Embodiment 3 of the present invention. In the second embodiment, the rectangular plate-like brackets 5, 5 having the guide holes 9, 9 are formed integrally with the motor housing 4. However, in the present embodiment, the vehicle body is disposed on the outer periphery of the motor housing 4. A convex attachment portion 5c for attaching the electric power steering device to 50 is integrally formed, and a smooth attachment surface 11 in contact with the vehicle body 50 side is formed on the upper portion of the attachment portion 5c. By increasing the area of the mounting surface 11 and increasing the area in contact with the vehicle body 50, the heat generated by the electric motor in the motor housing 4 can be radiated with higher efficiency. Further, two screw holes 10 and 10 are formed in the attachment surface 11 and attached to the upper attachment member 51a with hexagon bolts 53 and 53.

  The upper mounting member 51a is provided in the vicinity of the driver's seat of the vehicle body 50, and has a mounting plate 58 for mounting so as to contact the mounting surface 11 of the mounting portion 5c. The mounting plate 58 is provided with long elliptical mounting holes 55a and 55a in a direction substantially parallel to the axial direction of the motor housing 4, and the hexagon bolts 53 and 53 are inserted through the mounting holes 55a and 55a. The motor housing 4 is fixed by screwing with the screw holes 10 and 10 of 5c.

  FIG. 6 is a partially enlarged top view of the motor housing 4 of the electric power steering apparatus according to Embodiment 3 of the present invention. (A) has shown the thing of the same shape as the attachment part 5c shown in FIG. 5, (b) thru | or (h) has shown the other example of the shape of the attachment surface 11 of the attachment part 5c. The shape of the mounting surface 11 is not limited to the rectangle shown in (a), but may be a trapezoid shown in (b), a triangle shown in (c), or a circle shown in (d). Alternatively, it may be the star shape shown in (e), or may be a shape combining a plurality of straight lines and curves as shown in (f) to (h). The shape of the mounting surface 11 is not limited to the shape illustrated in FIG. 6, but may be any other shape suitable for the vehicle body 50, and the direction of the mounting surface 11 is also arbitrary.

  Moreover, although the two screw holes 10 and 10 drilled in the attachment surface 11 were used, not only this but 1 or 3 or more may be sufficient, and the position which drills the screw holes 10 and 10 is also shown in FIG. Not limited to position. Further, although one mounting portion 5c is integrally formed on the outer peripheral portion of the motor housing 4, the present invention is not limited to this, and two or more mounting portions may be integrally formed.

  The other configuration of the electric power steering apparatus according to the third embodiment is the same as that of the electric power steering apparatus according to the second embodiment, and therefore, the same parts are denoted by the same reference numerals and detailed description thereof is omitted. To do.

  In the embodiment of the present invention, the vehicle body 50 and the bracket 5 (5a, 5b) or the attachment portion 5c are fixed using the hexagon bolts 53, but the present invention is not limited thereto, and may be fixed by welding, for example. . Moreover, although the form provided with the bracket 5 (5a, 5b) or the attachment part 5c was shown near the upper end part of the outer peripheral part of the motor housing 4, the position of the bracket 5 (5a, 5b) or the attachment part 5c is an arbitrary position. Good. Further, the bracket 5 (5a, 5b) or the mounting portion 5c is integrated or integrally molded with the motor housing 4, but the lower bracket 6 may be integrated or integrally molded, and the steering device. In the case where has a tilt mechanism or a telescopic mechanism, an attachment member for attaching the tilt mechanism or an attachment member for attaching the telescopic mechanism may be integrated or integrally formed with the motor housing 4.

It is a side view which shows the structure of the principal part of the electric power steering apparatus which concerns on this invention. 1 is a perspective view of a motor housing of an electric power steering device according to Embodiment 1 of the present invention. It is a perspective view of the motor housing of the electric power steering apparatus which concerns on Embodiment 2 of this invention. It is a top view of the motor housing of the electric power steering apparatus which concerns on Embodiment 2 of this invention. It is a perspective view of the motor housing of the electric power steering device which concerns on Embodiment 3 of this invention. It is a partially expanded top view of the motor housing of the electric power steering apparatus according to Embodiment 3 of the present invention.

Explanation of symbols

1 Column shaft 4 Motor housing 5, 5a, 5b Bracket (mounting part)
5c Mounting portion 9 Guide hole 10 Screw hole 11 Mounting surface

Claims (2)

A column shaft connected to the steering wheel;
An electric motor that is coaxially connected to the column shaft in the middle of the column shaft and assists steering;
An electric power steering apparatus comprising: a cylindrical motor housing that houses the electric motor therein;
An electric power steering apparatus characterized in that an outer peripheral portion of the motor housing is integrally provided with an attachment portion to a vehicle body that protrudes in a radial direction of the outer peripheral portion of the motor housing.   The electric power steering apparatus according to claim 1, wherein the attachment portion is integrally formed with the motor housing.

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