JP2009035190A - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric power steering device attaining reduction of the number of parts used for a control unit and enhancement of assembling work efficiency. <P>SOLUTION: The control unit is provided with a control base plate mounted with a control element for controlling driving of an electric motor; a metal base plate mounted with a power element in which a drive current of the electric motor flows; an insert base member for electrically connecting the control base plate and the metal base plate; a case member for storing the control base plate, the metal base plate and the insert base member; and a cover member for covering the case member. The insert base member has a terminal base on a portion projected from the case member to the outside when it is stored in the case member, and is electrically connected to a battery through a wire harness connected to the terminal base by screw fastening. At least one terminal of the wire harness is fastened to the case member with the terminal base by one screw. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electric power steering apparatus using an electric motor as a generation source of steering assist torque, and more specifically, reducing the number of parts used in a control unit for controlling the driving of the electric motor and improving assembly workability. The present invention relates to an electric power steering apparatus that achieves the above.

  Many of recent vehicles are equipped with an electric power steering device (EPS) that assists the steering by the driver by transmitting the driving force of the electric motor to the steering shaft. In this electric power steering apparatus, a steering torque signal detected by a torque sensor is input to a control unit (ECU), and the control unit controls a drive current supplied to the electric motor based on the steering torque signal. The drive of the electric motor is controlled.

  The housing of this control unit is generally composed of a case member that accommodates various substrates and a cover member that covers the opening of the case member. As a structure for attaching the case member and the cover member, a structure in which several places are fastened and fixed by screws is known, and is disclosed in, for example, Patent Document 1.

  Hereinafter, a conventional control unit cover member and case member mounting structure will be described with reference to FIGS.

  FIG. 4 is a schematic side view showing a control unit according to the first conventional example.

  In the figure, a control unit 100 includes a case member 101 made of metal (aluminum or the like) that accommodates various substrates, and a cover member 102 that covers the opening of the case member 101. The cover member 102 is used for fixing. The case member 101 is fastened and fixed via screws 103 and 103. In addition, the control unit 100 houses an insert base member 104 that electrically connects various substrates in the case member 101. The insert base member 104 includes a power connection terminal block 105 at a portion protruding from the case member 101 when accommodated in the case member 101, and the power connection terminal block 105 is connected to the battery 106. The terminal 108 of the wire harness 107 thus connected is connected via a connection screw 109. In addition, the code | symbol 110 in FIG. 4 is a terminal block for motor connection which connects the control unit 100 and an electric motor (not shown).

  FIG. 5 is a schematic side view showing a control unit according to a second conventional example, and FIG. 6 is a schematic cross-sectional view showing a mounting engagement portion of the control unit according to the second conventional example. In these drawings, the same members as those in the first conventional example described above are denoted by the same reference numerals, and the description thereof is omitted.

  In the second conventional example, as shown in FIG. 5, attachment engaging portions 111A are formed at positions corresponding to the respective opening edges of the cover member 102A and the case member 101A. As shown in FIG. 6, the attachment engaging portion 111A is configured such that the engaging claw 112 formed on the cover member 102A is engaged with a sleeve 113 provided on the case member 101A, thereby allowing the cover member 102A to be attached to the case member. It has a snap-in structure that is fixedly attached to 101A.

  Further, FIG. 7 is a cross-sectional view of the main part showing the mounting engagement portion of the control unit according to the third conventional example. In the figure, the same members as those in the first conventional example and the second conventional example described above are denoted by the same reference numerals, and the description thereof is omitted.

  As shown in the figure, in the mounting engagement portion 111B according to the third conventional example, the engagement recess 114 formed in the cover member 102B is fitted into the engagement protrusion 115 provided in the case member 101B. Thus, the cover member 102A is attached and fixed to the case member 101A.

JP 2001-15944 A

  However, in the mounting structure as in the first conventional example described above, since several screw fastenings are required, the fastening screws 103 for the fastening locations and the fastening operation of the fixing screws 103 are necessary. There was a problem that it was difficult to reduce the number of points and improve the assembly workability.

  In addition, in the mounting structure as in the second conventional example, there is a possibility that rattling may occur between the cover member 102A and the case member 101A depending on the accuracy of the mold for forming the cover member 102A and the case member 101A. In this case, there is a problem that abnormal noise may occur due to transmission of vehicle vibration.

  Furthermore, in the mounting structure as in the third conventional example described above, an operation (step for crimping) of the engagement concave portion 114 of the case member 102B against the engagement convex portion 115 of the case member 101B is required. There was a problem that it was difficult to improve.

  Therefore, the present invention has been made in view of the above circumstances, and an object of the present invention is to reduce the number of parts used in the control unit and to improve the assembly workability of the control unit. The object is to provide a power steering device.

  An object of the present invention is to provide an electric motor that applies a steering assist force to a steering shaft connected to a steering wheel, a control unit that controls driving of the electric motor, and a battery that supplies electric power to the control unit. The control unit includes a control board on which a control element for controlling driving of the electric motor is mounted, a metal board on which a power element through which a driving current of the electric motor flows is mounted, and the control An insert base member that electrically connects the substrate and the metal substrate; a case member that accommodates the control substrate, the metal substrate, and the insert base member; and a cover member that covers the case member. When the base member is accommodated in the case member, A terminal block is provided in a portion protruding outward from the case member, and is electrically connected to the battery via a wire harness connected to the terminal block by screw fastening, and at least one of the wire harnesses This is achieved by fastening the terminal to the case member together with the terminal block with a single screw.

  Moreover, the said objective is achieved effectively when the said 1 screw further fastens the said cover member to the said case member with the said terminal and the said terminal block.

  Moreover, the said objective is effectively achieved because the said terminal is a terminal of the wire harness connected to the GND side of the said battery.

  Moreover, the said objective is effectively achieved by arrange | positioning the said electric motor and the said control unit in proximity | contact.

  Furthermore, the object is effectively achieved by the cover member being attached to the case member by a snap-in structure.

  According to the control unit of the electric power steering apparatus according to the present invention, the terminal of the wire harness connected to the battery is fastened to the case member together with the terminal block of the insert base member by one screw, thereby The connection of the terminal and the fixing of the insert base member can be realized with only one screw. As a result, the number of parts of the control unit can be reduced, and the assembly workability of the control unit can be improved.

  In the control unit of the electric power steering apparatus according to the present invention, not only the terminal of the wire harness and the terminal block of the insert base member but also the cover member are simultaneously fastened to the case member with one screw, thereby further controlling. The number of parts of the unit can be reduced, and the assembly workability of the control unit can be improved. In addition, when the cover member is screwed in this way, it is possible to reduce abnormal noise that may occur due to vehicle vibration.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a mechanism diagram showing a schematic configuration of an electric power steering apparatus according to an embodiment of the present invention.

  In the figure, the steering mechanism of the electric power steering apparatus 1 includes a steering shaft 3 that rotates in response to a steering operation of a steering wheel 2 attached to a tip portion, and a universal joint 4 on the other end side of the steering shaft 3. 5 and a rack and pinion mechanism 6 that converts the rotational motion of the steering shaft 2 into a linear motion of the rack shaft, and a tie rod 7 that transmits the motion of the rack shaft of the rack and pinion mechanism 6 to the steering wheel. It is composed of

  In addition, the column portion of the electric power steering apparatus 1 includes a torque sensor 8 that detects a steering torque input to the steering shaft 3 via the steering wheel 2 and a steering coupled to the steering shaft 3 via the speed reduction mechanism 9. An auxiliary electric motor 10 is provided.

  The drive of the electric motor 10 is controlled by a control unit (ECU) 11 disposed in the vicinity of the electric motor 10. Electric power is supplied from the battery 12 to the control unit 11, and an ignition key signal is input from the ignition key 13. Then, the control unit 11 calculates the steering assist command value I based on the steering torque value T detected by the torque sensor 8 and the vehicle speed V detected by the vehicle speed sensor 14, and the calculated steering assist command value I is calculated. The drive current supplied to the electric motor 10 is controlled accordingly.

  The electric power steering device 1 described above is of a column assist type in which the electric motor 10 is disposed in the column portion. However, the present invention is not limited to this, and for example, the electric motor 10 is disposed in the pinion portion. The pinion assist type may be used, or the rack assist type in which the electric motor 10 is disposed in the rack portion.

  2 is an exploded perspective view showing a schematic configuration of the control unit in FIG. 1, and FIG. 3 is a schematic side view showing a state in which the control unit in FIG. 2 is assembled.

  As shown in FIG. 2, the box-shaped external housing of the control unit 11 is arranged so as to cover the case member 15 that forms the base and the opening of the case member 15, and is housed in the case member 15. And a cover member 16 that electrically shields. A metal substrate 19 on which power elements such as FETs (field effect transistors) 17 and relays 18 necessary for driving the electric motor 10 are mounted is fixed to the case member 15 with screws or the like.

  The metal substrate 19 is formed of a material such as a metal (aluminum or the like) or ceramic having excellent heat conductivity and heat transfer properties, and the case member 15 generates heat of the power element generated by the drive current of the electric motor 10 flowing. It is designed to conduct well. Thereby, the heat of the power element generated by energization is efficiently dissipated to the outside of the control unit 11 by the function of the case member 15 as a heat sink (heat radiating plate).

  Above the metal board 19, a control board 20 composed of an insulating printed board on which a control element such as a microcomputer for controlling the driving of the electric motor 10 and its peripheral circuits is mounted is disposed. Between the two, an insert base member 23 in which the conductive metal plate 21 and the resin base material 22 are integrally formed by insert molding is disposed.

  The substrate housed inside the control unit 11 has a two-sheet structure including a metal substrate 19 on which components that generate relatively large heat when energized and a control substrate 20 that mounts components that generate relatively small heat when energized. And each board | substrate 16 and 17 has a structure electrically connected by the electroconductive metal plate 21 of the insert base member 23. FIG. With this structure, a large current can be supplied to the electric motor 10 and the control unit 11 can be downsized.

  The insert base member 23 includes a power connection terminal block 24 at a portion (left side in FIG. 3) that protrudes from the case member 15 when accommodated in the case member 15, and the power connection terminal block 24 includes the battery 12. The terminal 26a of the wire harness 25a connected to the GND side and the terminal 26b of the wire harness 25b connected to the power source side of the battery 12 are fixed via screws 27a and 27b, respectively. Of these two screws 27a and 27b, the connecting screw 27a for the GND-side wire harness 25a is longer than the connecting screw 27b for the power-side wire harness 25b. The screw 27a inserted into the terminal 26a of the GND-side wire harness 25a is a screw hole 29 formed in the case member 15 via the bolt insertion hole 28 formed in the cover member 16 and the power supply terminal block 24. On the other hand, the screw 27b inserted into the terminal 26b of the power supply side wire harness 25b is fastened to the power supply terminal block 24. Thereby, the terminals 26a and 26b of the wire harnesses 25a and 25b and the power supply terminal block 24 are connected to each other via the screws 27a and 27b, and the control unit 11 and the wire harnesses 25a and 25b are electrically connected. The

  Further, the cover member 16 and the case member 15 are provided with the above-described snap-in structure (see FIG. 6) mounting engagement portions 30 and 30 at positions corresponding to the respective opening edge portions. The cover member 16 is fixedly attached to the case member 15 by the snap-in coupling of.

  2 and 3 is a motor connection terminal block for connecting the control unit 11 and the electric motor 10, and the control unit 11 is connected to the electric motor 10 via the motor connection terminal block 31. Is electrically connected.

  As described above, in the control unit 11 of the electric power steering apparatus 1 according to this embodiment, the terminal 26a of the GND-side wire harness 25a is connected to the case together with the cover member 16 and the power connection terminal block 24 by one screw 27a. The structure is such that the member 15 is fastened simultaneously. With this fastening structure, the connection of the terminal 26a of the GND side wire harness 25a and the fixing of the cover member 16 and the insert base member 23 can be realized by only one screw screw 27a. As a result, the number of parts used for the control unit 11 is reduced, and the time and labor required for the assembly workability of the control unit 11 are reduced.

  Further, by fastening the cover member 16 via the screw 27a, it is possible to prevent looseness that is likely to occur when the cover member 16 is attached to the case member 15 with a snap-in structure. It is possible to reduce the occurrence of abnormal noise that has become a problem in the control unit 11.

  As mentioned above, although embodiment of this invention was described concretely, this invention is not limited to this, In the range which does not deviate from the meaning, it can change suitably.

It is a mechanism figure showing a schematic structure of an electric power steering device concerning an embodiment of the present invention. It is a disassembled perspective view which shows schematic structure of the control unit of FIG. It is a schematic side view which shows the state by which the control unit of FIG. 2 was assembled. It is a schematic side view which shows the control unit which concerns on a 1st prior art example. It is a schematic side view which shows the control unit which concerns on a 2nd prior art example. It is a schematic sectional drawing which shows the attachment engaging part of the control unit which concerns on a 2nd prior art example. It is a schematic sectional drawing which shows the attachment engaging part of the control unit which concerns on a 3rd prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electric power steering apparatus 2 Steering wheel 3 Steering shaft 11 Control unit (ECU)
12 Battery 15 Case member 16 Cover member 19 Metal substrate 20 Control substrate 23 Insert base member 24 Power supply terminal block 25a Wire harness (GND side)
26a terminal (GND side)
27a Screw (GND side)
28 Bolt insertion hole 29 Screw hole 30 Mounting engagement part (snap-in structure)

Claims (5)

An electric power steering apparatus comprising: an electric motor that applies a steering assist force to a steering shaft coupled to a steering wheel; a control unit that controls driving of the electric motor; and a battery that supplies electric power to the control unit Because
The control unit includes a control board on which a control element for controlling driving of the electric motor is mounted, a metal board on which a power element through which a driving current of the electric motor flows is mounted, and the control board and the metal board are electrically connected An insert base member to be connected; a case member that accommodates the control substrate, the metal substrate, and the insert base member; and a cover member that covers the case member,
The insert base member has a terminal block at a portion protruding outside from the case member when accommodated in the case member, and is electrically connected to the battery via a wire harness connected to the terminal block by screw fastening. Connected, and
At least one terminal of the wire harness is fastened to the case member together with the terminal block by one screw.   The electric power steering apparatus according to claim 1, wherein the one screw further fastens the cover member to the case member together with the terminal and the terminal block.   The electric power steering apparatus according to claim 1, wherein the terminal is a terminal of a wire harness connected to the GND side of the battery.   The electric power steering apparatus according to any one of claims 1 to 3, wherein the electric motor and the control unit are arranged close to each other.   The electric power steering apparatus according to claim 1, wherein the cover member is attached to the case member by a snap-in structure.

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