JP2009023458A - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power steering device including a unit cover that surely protects a stored control substrate while being excellent in impact resistance even if an impact force is applied. <P>SOLUTION: A protective-plate part 28 of a metal unit cover 26 is arranged so as to cover a control substrate 25 from the vehicle rear side. The protective-plate part 28 is formed with belt-like first-third recessed parts 38, 39, and 40. Ribs 38b, 39b, and 40b are radially formed respectively along each of the first-third recessed parts 38, 39, and 40. The ribs 38, 39, and 40 are reinforcement parts for the first protective-plate part 28 that are excellent in impact resistance against an impact force applied from the vehicle rear side. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention provides an electric motor including an electric motor that transmits a steering assist force to a steering shaft via a reduction mechanism in a reduction gear box, and a control unit that includes a control board on which a control circuit that drives and controls the electric motor is mounted. The present invention relates to a power steering device.

The control unit mounted on the reduction gear box of the electric power steering apparatus includes a control board on which a control circuit for driving and controlling the electric motor that transmits the steering assist force is mounted, and the control board is housed in the unit cover. And mounted in a reduction gear box (for example, Patent Document 1).
In the unit cover of Patent Document 1, the substrate surface on which the control circuit of the control substrate is mounted is covered with a resin cover member.
JP 2001-196770 A

By the way, even if the resin cover member of the apparatus of Patent Document 1 described above is a member having a large thickness, resistance to impact force is weak. For this reason, if the resin cover member is damaged, the stored control board may be affected.
Therefore, the present invention has been made paying attention to the above-mentioned unsolved problems of the conventional example, and is a unit that is excellent in impact resistance even when an impact force is applied, and can reliably protect the control board accommodated therein. An object of the present invention is to provide an electric power steering apparatus having a cover.

  In order to achieve the above object, an electric power steering apparatus according to a first aspect of the present invention includes a steering column having a steering shaft to which steering torque is transmitted, and a steering assist to the steering shaft via a reduction mechanism in a reduction gear box. An electric power steering apparatus comprising: an electric motor for transmitting force; and a control unit including a control board on which a control circuit for driving and controlling the electric motor is mounted. The control unit houses the control board and reduces the deceleration A metal unit cover mounted on the outer periphery of the gear box is provided, and this unit cover is provided with a protection plate portion that covers the board surface on which the control circuit of the control board is mounted, and the protection An impact reinforcement portion having impact resistance is provided on the plate portion.

According to a second aspect of the present invention, in the electric power steering apparatus according to the first aspect, the impact reinforcing portion protrudes from the outer peripheral surface or the inner peripheral surface of the protection plate portion, and is linear along the surface direction. It is the reinforcement rib extended in.
According to a third aspect of the present invention, in the electric power steering apparatus according to the second aspect of the present invention, the reinforcing rib forms a strip-shaped concave portion on the outer peripheral surface or inner peripheral surface of the protective plate portion, and the width of the concave portion. It is the site | part which protrudes from the said inner peripheral surface or outer peripheral surface in the edge part of a direction.

  Furthermore, the invention according to claim 4 is the electric power steering apparatus according to claim 2 or 3, wherein a plurality of the reinforcing ribs are formed so as to extend over the entire outer peripheral surface or inner peripheral surface of the protective plate portion. did.

According to the electric power steering apparatus according to the present invention, the protection plate portion of the metal unit cover that houses the control board and is mounted on the outer periphery of the reduction gear box is provided with the impact reinforcement portion having impact resistance and is protected. Even if an impact force collides with the plate portion, the impact reinforcement portion exhibits impact resistance, so that the control board on which the control circuit is mounted can be reliably protected.
Further, since the rigidity of the unit cover is improved, the operation sound of the relay of the built-in control unit and the operation sound of the electric motor can be reduced.

Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described in detail with reference to the drawings.
FIG. 1 is a perspective view showing a right-hand drive vehicle according to an embodiment of the electric power steering apparatus according to the present invention, and FIG. 2 is a perspective view showing the embodiment from the left. Fig. 4 is a front view of this embodiment, Fig. 4 is a longitudinal sectional view showing the main part of the reduction gear box, Fig. 5 is a perspective view showing the appearance of the reduction gear box, and Fig. 6 shows the connection relationship between the electric motor and the control unit. 7 is a front view showing the internal structure of the electric motor, FIG. 8 is an exploded perspective view of the control unit, FIG. 9 is a perspective view showing the cover of the control unit, and FIG. 10 is a view taken along line AA in FIG. FIG.

  In FIG. 1, reference numeral 1 denotes a column-type electric power steering device, in which a reduction gear box 4 is connected to a steering column 3 that rotatably houses a steering shaft 2 connected to a steering wheel (not shown). An electric motor 5 whose axial direction is extended in a direction perpendicular to the axial direction of the steering column 3 is disposed in the reduction gear box 4.

  The steering column 3 has a double tube structure of an inner tube 3a and an outer tube 3b. The outer tube 3 b and the reduction gear box 4 of the steering column 3 are attached to the vehicle body side by an upper mounting bracket 6 and a lower mounting bracket 7. The lower mounting bracket 7 is composed of a mounting plate portion 7a attached to a vehicle body side member (not shown) and a pair of support plate portions 7b extending in parallel from the lower surface of the mounting plate portion 7a with a predetermined distance in the left-right direction. Is formed. And the lower end of the support plate part 7b is rotatably connected to the support part 4b integrally formed in the vehicle body front side of the reduction gear box 4 via the pivot 7c.

  The upper mounting bracket 6 includes a mounting plate portion 6a attached to a vehicle body side member (not shown) and a pair of support plate portions fixed to the lower end of the mounting plate portion 6a and spaced apart in the left-right (vehicle width) direction. 6b and a tilt mechanism 6c for supporting the outer tube 3b of the steering column 3 formed on the pair of support plate portions 6b. Then, the tilt lever 6g of the tilt mechanism 6c is rotated to release the support state of the outer tube 3b, whereby the tilt position of the steering column 3 can be adjusted up and down around the pivot 7c of the lower mounting bracket 7. .

As shown in FIG. 4, the steering shaft 2 includes an input shaft 2a whose upper end is connected to a steering wheel (not shown), and a torsion bar 2b connected to the lower end of the input shaft 2a via a torsion bar 2b. It is comprised with the output shaft 2c to cover.
The reduction gear box 4 is formed by die-casting, for example, any one of materials having high thermal conductivity, such as aluminum, aluminum alloy, magnesium, and magnesium alloy. As shown in FIGS. 4 and 5, the reduction gear box 4 includes a worm storage portion 12 that stores a worm 11 connected to an output shaft (not shown) of the electric motor 5, and a lower side of the worm storage portion 12. A worm wheel storage portion 14 for storing a worm wheel 13 having a central axis perpendicular to the central axis thereof and meshing with the worm 11, and a torque integrally and coaxially connected to the rear side of the worm wheel storage portion 14 in the vehicle body. Torque sensor storage portion 16 for storing the sensor 15, motor mounting portion 17 for attaching the electric motor 5 formed on the open end surface of the worm storage portion 12, and a cylindrical shape formed at the rear end of the vehicle body of the torque sensor storage portion 16. A control unit device for mounting a column mounting portion 18 and a control unit 19 formed over part of the worm storage portion 12 and the worm wheel storage portion 14. And a part 20. The front end portion of the vehicle body of the steering column 3 is externally fitted and connected to the column mounting portion 18 of the reduction gear box 4.

  Here, as shown in FIG. 4, the torque sensor 15 magnetically detects the twisted state between the input shaft 2a and the output shaft 2c of the steering shaft 2 and transmits the steering torque transmitted to the steering shaft to a pair of detection coils. The external connection terminals 15c and 15d are configured to be detected by 15a and 15b and project outwardly in parallel to the direction perpendicular to the central axis of the steering column 3 at the start and end of winding of the pair of detection coils 15a and 15b, respectively. 15e and 15f are connected, and the protruding portions of the external connection terminals 15c to 15f are bent at the central portion in parallel with the central axis of the steering column 3 to form an L shape.

  As shown in FIG. 6, the electric motor 5 has connection terminals 5c and 5d formed at positions close to and opposed to the control unit 19 mounted on the control unit mounting portion 20 at a position close to the mounting flange 5b. As shown in FIG. 7, each of the connection terminals 5c and 5d is insulated from each other in a synthetic resin brush support 5f having an armature insertion hole in the center of the bottom, and is connected to two sets of brushes 5g and 5h. The arc-shaped connection terminals 5i and 5j that are individually connected are integrally formed at opposite ends.

  As shown in FIG. 5, the control unit mounting portion 20 formed in the reduction gear box 4 is formed so as to face the vehicle body rear side at the worm storage portion 12 and the upper side of the worm wheel storage portion 14 below the worm storage portion 12. The flat mounting surface 20a and a rectangular unit mounting surface that is orthogonal to the flat mounting surface 20a and the flat mounting surface 20a formed on the top surface of the torque sensor storage portion 16 and that extends in the left-right direction. It is formed in an L shape when viewed from the left and right direction.

Here, an opening portion 20 d communicating with the internal space of the torque sensor storage portion 16 that stores the torque sensor 15 is formed in the center portion in the left-right direction of the unit mounting surface 20 b of the control unit mounting portion 20. The external connection terminals 15c to 15f of the torque sensor 15 are provided so as to protrude above the unit mounting surface 20b through the opening 20d.
Also, a frame mounting surface 20c having a narrow width is formed on the rear end surface of the motor mounting portion 17 in parallel to the flat mounting surface 20a and at a position on the rear side of the vehicle body from the flat mounting surface 20a.

As shown in FIG. 8, the control unit 19 mounted on the control unit mounting unit 20 includes a metal heat dissipation plate 21 having a high heat transfer rate, a power board 23, a rectangular frame-shaped synthetic resin frame 24, A control board 25 and a cover 26 are provided.
The heat radiating plate 21 is directly fixed to the flat mounting surface 20a of the control unit mounting portion 20 via heat radiating grease. The power board 23 is a discrete component 23a, 23b such as an H bridge circuit composed of a power switching element such as a field effect transistor that drives and controls the electric motor 5, and a pulse width modulation circuit that drives the power switching element of the H bridge circuit. Is implemented.

  A synthetic resin frame 24 surrounds the power board 23. The control board 25 is attached to the front surface of the synthetic resin frame 24 and has through holes 25a to 25d that are directly inserted through the external connection terminals 15c to 15f of the torque sensor 15. A steering assist current command value is calculated based on the vehicle speed detection value from the vehicle speed sensor that is not operated, and current feedback control is performed based on the steering assist current command value and the detected value of the motor current output to the electric motor 5 to obtain a power board By calculating a voltage command value to the pulse width modulation circuit 23, a discrete unit 25e such as a micro control unit (MCU) for controlling a steering assist force generated by the electric motor 5 and its peripheral devices is mounted. The cover 26 covers the power board 23, the synthetic resin frame 24, and the control board 25.

  The synthetic resin frame 24 includes a rectangular frame-shaped frame main body 24a, a mounting plate portion 24b formed on the left end of the frame main body 24a and fixed to the frame mounting surface 20c of the reduction gear box 4, and the mounting plate portion 24b. A terminal block 24c fixed on the top and electrically connected to the connection terminals 5c and 5d of the electric motor 5 and a female connector 45 fixed to the right end of the frame body 24a are provided. The female connector 45 is connected to a power supply connector 45a connected to a battery (not shown) via a power supply male connector 46, and a network such as CAN that exchanges data with control devices in each part of the vehicle body. And a signal connector 45b. The power board 23 and the control board 25 are connected via the connection terminal 22a.

  Further, as shown in FIGS. 8 and 9, the cover 26 is a metal member, and is orthogonal to the rectangular first protection plate portion 28 and the longitudinal edge portion of the first protection plate portion 28. The second and third protective plate portions 29, 30 extending in the same direction as the second and third protective plate portions 29, 30 from the edge in the short direction of the first protective plate portion 28. The fourth and fifth protective plate portions 31, 32, the second protective plate portion 29, and the screws formed in the direction perpendicular to the outside of the cover from the end portions of the fourth and fifth protective plate portions 31, 32. And fixed pieces 34 to 37 each having a passage hole 33.

The fourth protective plate portion 31 is formed with a notch 31 a surrounding the outer periphery of the female connector 45. Further, the fifth protective plate part 32 is formed with a notch 32a surrounding the board side of the terminal block 24c. The second protection plate 29 is also formed with notches 29a to 29d.
Here, as shown in FIG. 9, on the outer peripheral surface of the first protection plate portion 28 of the cover 26, strip-shaped first and second recesses extending in the longitudinal direction while being spaced apart from each other in the short direction. 38 and 39, and a belt-like third recess 40 extending in the short direction and connecting the central portions of the first and second recesses 38 and 39 in the longitudinal direction are formed.

  As shown in FIG. 10, the first recess 38 is formed at the end in the width direction between the outer peripheral surface of the first protective plate portion 28 and the bottom surface 38 a recessed inward from the outer peripheral surface, with respect to the outer peripheral surface. Ribs 38b are formed in the orthogonal direction. The second recess 39 is also ribbed in the direction perpendicular to the outer peripheral surface at the end in the width direction between the outer peripheral surface of the first protective plate portion 28 and the bottom surface 39a recessed inward from the outer peripheral surface. 39b is formed. Further, the third recess 40 is also provided with ribs 40b in the direction perpendicular to the outer peripheral surface at the end in the width direction between the outer peripheral surface of the first protective plate portion 28 and the bottom surface recessed inward from the outer peripheral surface. Is formed.

The rib 38 b of the first recess 38 and the rib 40 b of the third recess 40 are connected on the center side of the first protection plate portion 28. Further, the rib 39 b of the second recess 39 and the rib 40 b of the third recess 40 are also connected on the center side of the first protection plate portion 28.
The control unit 19 configured as described above is mounted on the control unit mounting portion 20 of the reduction gear box 4 and, as shown in FIG. 6, a terminal block 24c fixed to the mounting plate portion 24b of the synthetic resin frame 24. The connection terminals 5c and 5d of the electric motor 5 are electrically connected. As shown in FIGS. 1 to 3, the electrically connected terminal block 24 c and connection terminals 5 c and 5 d are covered with a synthetic resin terminal cover denoted by reference numeral 27.

Next, the operation of the above embodiment will be described.
When power is supplied from the battery to the power board 23 and the control board 25 by turning on an ignition switch (not shown) of the vehicle body, steering assist control processing is executed by the micro control unit (MCU), and the torque sensor 15 and a vehicle speed sensor (not shown) are connected. A steering assist current command value is calculated based on the detected value. A current feedback process is executed based on the steering assist current command value and the motor current detected by the motor current detection unit to calculate a voltage command value. By supplying this voltage command value to the gate drive circuit of the power board 23 and controlling the H bridge circuit, a motor drive current flows through the electric motor 5 and the electric motor 5 needs to be operated in the forward or reverse direction. Drive to generate force.

For this reason, a steering assist force corresponding to the steering torque of the steering wheel is generated from the electric motor 5, and this steering assist force is transmitted to the output of the steering shaft 2 via the worm 11 and the worm wheel 13, thereby the steering wheel. Can be steered with a light steering force.
Here, according to the present embodiment, the control unit 19 mounted on the control unit mounting portion 20 of the reduction gear box 4 is controlled by the first protection plate portion 28 of the metal cover 26 as shown in FIG. It arrange | positions in the state which covered the board | substrate 25 from the vehicle rear side.

  The first protective plate 28 includes strip-shaped first and second recesses 38 and 39 extending in the longitudinal direction while being spaced apart from each other in parallel in the short length direction, and first and second strips extending in the short length direction. A band-shaped third recess 40 is formed connecting the longitudinal center portions of the second recesses 38, 39, and ribs 38b, 39b, 40b are formed along the first to third recesses 38, 39, 40. The ribs 38b, 39b, and 40b serve as reinforcing portions of the first protective plate portion 28 that have excellent impact resistance against the impact force applied from the vehicle rear side.

Therefore, even if an impact object collides with the first protection plate portion 28 of the control unit 19 from the rear side of the vehicle, the first protection plate portion 28 is not easily deformed by the ribs 38b, 39b, and 40b of the reinforcement portion. It is possible to reliably protect the control board 25 arranged on the board.
Further, the ribs 38b, 39b, 40b formed on the first protective plate portion 28 of the present embodiment are provided with intersecting portions (the rib 38b of the first recess 38, the rib 40b of the third recess 40, the second The rib 39b of the concave portion 39 and the rib 40b of the third concave portion 40) and the large impact force applied from the vehicle rear side of the first protective plate portion 28 can have high impact resistance.

In addition, since the rigidity of the first protective plate portion 28 of the metal cover 26 is improved, the operating noise of the relay circuit of the built-in power board 23 and the operating noise of the adjacent electric motor 5 can be reduced. it can.
Furthermore, since the first protective plate portion 28 has high impact resistance that is not easily deformed, the inner surface of the metal first protective plate portion 28 is prevented from being short-circuited due to contact with the control board 25. Therefore, it is not necessary to attach an electrical insulating material such as an insulating sheet for reducing the manufacturing cost.

In this embodiment, the ribs 38b, 39b, and 40b are formed by forming the band-shaped first to third recesses 38, 39, and 40 in the first protective plate portion 28. The shape is not limited to this, and the same effect can be obtained even if a plurality of concave portions are formed in, for example, a cross beam shape or an X shape.
In the present embodiment, the band-shaped first to third recesses 38, 39, and 40 are formed on the outer peripheral surface of the first protective plate portion 28, but the first belt-shaped first portion is formed on the inner peripheral surface of the first protective plate portion 28. The same effect can be produced even when the third recess is formed, that is, when the belt-shaped protrusion is provided on the outer peripheral surface of the first protective plate 28.

In the above embodiment, the case where the electric motor 5, the control unit 19, and the female connector 45 are arranged in a straight line along a line orthogonal to the central axis of the steering column 3 has been described. However, the present invention is not limited to this. Instead of this, they may be arranged in a straight line along a line intersecting the central axis of the steering column 3.
Moreover, in the said embodiment, although the case where a brush motor was applied as the electric motor 5 was demonstrated, it is not limited to this, You may make it apply a brushless motor, In this case, a connection terminal 5c and 5d are connected to the power supply side of the excitation coil of each phase, and, for example, an inverter circuit having a field effect transistor (FET) for driving a brushless motor on the power board 23 and a gate of the field effect transistor of the inverter circuit are pulse width modulated. A gate driving circuit driven by a signal may be mounted.

  Furthermore, in the above-described embodiment, the case where the present invention is applied to a right-hand drive vehicle has been described. However, the present invention is not limited to this, and when applied to a left-hand drive vehicle, the reduction gear box 4 and the electric motor 5 are used. The control unit 19 is arranged symmetrically with respect to the vertical plane passing through the central axis of the steering column 3, that is, the electric motor 5 is arranged on the right side of the control unit 19, and the female connector 45 and the terminal block 24c of the control unit 19 are connected. The electric motor 5 may be disposed on the left side, and the electric connector 5 and the female connector 45 and the terminal block 24c may be disposed on the inner side of the vehicle body.

It is the perspective view shown from the right direction at the time of applying one Embodiment of the electric power steering device which concerns on this invention to a right-hand drive vehicle. It is the perspective view which showed the apparatus of FIG. 1 from the left direction. It is a front view of the apparatus of FIG. It is a longitudinal cross-sectional view which shows the principal part of the reduction gear box which comprises an electric power steering apparatus. It is a perspective view which shows the external appearance of the reduction gear box which comprises an electric power steering device. It is a perspective view which shows the connection relation of the electric motor which comprises an electric power steering apparatus, and a control unit. It is a front view which shows the internal structure of the electric motor which comprises an electric power steering apparatus. It is a disassembled perspective view of a control unit. It is a perspective view which shows the cover of a control unit. It is an AA arrow line view of FIG.

Explanation of symbols

  2 ... steering shaft, 2a ... input shaft, 2b ... torsion bar, 2c ... output shaft, 3 ... steering column, 3a ... inner tube, 3b ... outer tube, 4 ... reduction gear box, 4b ... support, 5 ... electric motor 5b ... mounting flange, 5c, 5d ... connection terminal, 5f ... brush support, 5g, 5h ... brush, 5i, 5j ... connection terminal, 6 ... upper mounting bracket, 6a ... mounting plate, 6b ... support plate, 6c ... Tilt mechanism, 6g ... Tilt lever, 7 ... Lower mounting bracket, 7a ... Mounting plate part, 7b ... Supporting plate part, 7c ... Axis, 11 ... Worm, 12 ... Worm storage part, 13 ... Worm wheel, 14 ... Worm Wheel housing part, 15 ... torque sensor, 15a, 15b ... detection coil, 15c-15f ... external connection terminal, 16 ... torque sensor housing part, 17 ... motor mounting part, 18 ... Ram mounting portion, 19 ... control unit, 20 ... control unit mounting portion, 20a ... flat mounting surface, 20b ... unit mounting surface, 20c ... frame mounting surface, 20d ... opening, 21 ... radiation plate, 22a ... connection terminal, DESCRIPTION OF SYMBOLS 23 ... Power board, 23a, 23b ... Discrete components, 24 ... Synthetic resin frame, 24a ... Frame main body, 24a1 ... Side plate (unit side mounting surface) of frame main body, 24b ... Mounting plate portion, 24c ... Terminal block, 25 ... Control board, 25a to 25d ... through hole, 25e ... discrete parts, 26 ... cover (unit cover), 27 ... terminal cover, 28 ... first protection plate (protection plate), 29 ... second protection plate, 29a ~ 29d ... Notch, 30 ... 3rd protection board part, 31 ... 4th protection board part, 32 ... 5th protection board part, 33 ... Screw passage hole, 34-37 ... Fixed piece 38 ... first belt-like recess, 39 ... second belt-like recess, 40 ... third belt-like recess, 38a ... bottom surface of first recess, 38b, 39b, 40b ... rib (reinforcement rib), 39a ... second recess Bottom surface, 45 ... female connector, 45a ... power connector, 45b ... signal connector, 46 ... male connector for power supply

Claims (5)

A steering column with a steering shaft to which steering torque is transmitted, an electric motor that transmits a steering assist force to the steering shaft via a reduction mechanism in a reduction gear box, and a control circuit that controls driving of the electric motor are mounted. In an electric power steering apparatus comprising a control unit including a control board,
The control unit includes a metal unit cover that houses the control board and is mounted on an outer periphery of the reduction gear box, and the unit cover is a board on which the control circuit of the control board is mounted. While providing a protective plate that covers the surface,
An electric power steering apparatus characterized in that an impact reinforcing part having impact resistance is provided on the protective plate part.   2. The electric motor according to claim 1, wherein the impact reinforcing portion is a reinforcing rib that protrudes from an outer peripheral surface or an inner peripheral surface of the protection plate portion and extends linearly along the surface direction. Power steering device.   The reinforcing rib is a portion that forms a band-shaped concave portion on the outer peripheral surface or inner peripheral surface of the protective plate portion, and projects from the inner peripheral surface or outer peripheral surface at the end in the width direction of the concave portion. The electric power steering apparatus according to claim 2.   4. The electric power steering apparatus according to claim 2, wherein a plurality of the reinforcing ribs are formed so as to extend over the entire outer peripheral surface or inner peripheral surface of the protective plate portion.   The electric power steering apparatus according to claim 4, wherein the plurality of reinforcing ribs intersect each other.

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