JP2014180875A - Electric power steering system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To diminish an adverse effect of oscillation of an electric motor or the like of an electric power steering system, and suppress degradation of durability.SOLUTION: In a rack housing 5, a deceleration mechanism accommodation unit 5c that accommodates a deceleration mechanism 4a interposed between an electric motor 4 and a rack shaft 3, and a gear mechanism accommodation unit 5b that accommodates a gear mechanism 2d linking a steering mechanism 2 and the rack shaft 3 are formed at positions distant in an extending direction of the rack shaft 3. An electronic control unit 6 is fixed to the peripheral side of the rack housing 5 at a position between the deceleration mechanism accommodation unit 5c and gear mechanism accommodation unit 5b (fixed to a rack shaft accommodation unit 5a). The electric motor 4 is fixed to the peripheral side of the deceleration mechanism accommodation unit 5c, and at least part of connection wirings 4c and 4d between the electric motor 4 and electronic control unit 6 is stowed in the rack housing 5.

Description

  The present invention relates to an electric power steering apparatus that assists steering by a steering mechanism using an electric motor as a drive source.

  2. Description of the Related Art In recent years, an electric power steering device that assists steering by a steering mechanism (a steering wheel, a steering column, etc.) using an electric motor as a drive source is known. The electric power steering device includes an electronic control device that controls driving of the electric motor in accordance with the steering torque. The electronic control device is attached and fixed to an electric motor in a cantilever shape on one side of the electronic control device (for example, Patent Document 1).

JP 2011-131624 A

  However, in the electronic control device attached to the electric motor as described above, when the vibration of the vehicle body is transmitted to the electronic control device, the vibration of the electronic control device becomes large, and the durability may be reduced.

  An object of the present invention is to provide an electric power steering apparatus capable of reducing the influence of vibration as described above and suppressing a decrease in durability.

  An electronic control device according to the present invention is a creation that can solve the above-described problems, and one aspect thereof is an electric power steering device that assists steering of a steering mechanism with an auxiliary torque by an electric motor, through a gear mechanism. Accommodates a rack shaft connected to the steering mechanism for transmitting the steering torque of the steering mechanism to the wheels, a reduction mechanism for reducing the rotation of the electric motor and transmitting auxiliary torque to the rack shaft, and the rack shaft and the reduction mechanism. And an electronic control unit that drives and controls the electric motor. The electric motor is fixed to a speed reduction mechanism accommodation position in the rack housing, and the electronic control unit accommodates a rack shaft on the outer peripheral side of the rack housing. It is fixed in position.

  As described above, according to the present invention, it is possible to reduce the influence of vibration of the electric motor in the electric power steering apparatus and suppress the deterioration of durability.

1 is a schematic cross-sectional view showing an example of an electric power steering device in the present embodiment. 1 is a schematic external view showing an example of an electric power steering device in the present embodiment. 1 is a schematic external view showing an example of an electronic control device. The schematic sectional drawing which follows the XX line of the electronic control unit of FIG. FIG. 5 is a schematic cross-sectional view illustrating an example of an assembly process of the electronic control device of FIG. 4. FIG. 5 is an enlarged schematic cross-sectional view of a part of the electronic control device of FIG. 4. Schematic (metal board | substrate) which shows an example of the multilayer board | substrate accommodated in an electronic controller. FIG. 8 is a schematic diagram showing a part of the multilayer substrate in FIG. 7 (power supply circuit board). Schematic (inverter circuit board) which shows a part of multilayer board | substrate of FIG. Schematic (control board) which shows an example of the multilayer board | substrate accommodated in an electronic controller. Schematic which shows an example of the connection structure of the connection part for electric power supply (terminal for phase currents). The schematic external view which shows the modification of the electric power steering apparatus in this embodiment. FIG. 13 is a partially exploded view of the electric power steering device of FIG. 12. Schematic which shows the modification of the multilayer substrate accommodated in an electronic controller (metal substrate).

  The electric power steering device according to the embodiment of the present invention has a configuration in which the electronic control device is not attached to the electric motor but is attached to the rack shaft housing position on the outer peripheral side of the rack housing.

  Conventionally, the electronic control device is fixed so as to be supported in a cantilevered manner on the coaxial core of the electric motor as in Patent Document 1, for example, based on the idea of attaching the electronic control device close to the electric motor to be controlled. Although an electric power steering device having a configuration has been known, in such a configuration, a resonance frequency that can occur in the electronic control device tends to be low, and the electronic control device is caused by vibration of the electric motor due to vibration of the vehicle body. There was a risk of causing various effects due to vibration (for example, vibration at a low frequency). For example, damage (for example, cracks in a solder joint or the like) occurs in an electronic control device casing or an electronic component mounted on a circuit board in the casing, or a connection portion between the electronic control device and an electric motor or the like. (For example, in the case of a configuration using tightening means such as bolts, the tightening means is worn or loosened).

  On the other hand, according to the configuration in which the electronic control device is fixed to the rack shaft housing position on the outer peripheral side of the rack housing as in the present embodiment, the electronic control device is not structured to be fixed to the electric motor in a cantilevered manner. By fixing the entire apparatus to the rack housing in a planar manner, the resonance frequency as described above can be increased, and the influence of the road surface condition during driving of the automobile and the vibration of the vehicle body due to engine driving can be reduced. Also, if the rack housing has heat dissipation, the rack housing itself becomes a thermal mass, so the amount of thermal mass increases compared to the case where the electronic control device is fixed to the electric motor in a cantilever shape, Heat transfer will be improved. Further, since the electronic control unit is fixed to the rack housing (preferably integrally fixed), the rack housing can be used as a heat radiating member, so that the heat radiating area is increased and the heat radiating property to the rack housing is improved. Furthermore, by mounting the electronic parts in the form of a long flat plate, in other words, by extending the rack axis direction and mounting the electronic parts on the metal board, the heat dissipation area is increased and the heat dissipation is improved. To do. For this reason, the temperature rise of the electronic control device is suppressed and the thermal influence is reduced.

  By reducing the influence of vibration and thermal influence in this way, it is possible to suppress a decrease in durability of the electric power steering apparatus and to prolong the product life.

  As long as the electronic control device is fixed to the rack shaft housing position on the outer peripheral side of the rack housing as described above, the other various configurations (configurations necessary for the electric power steering device, etc.) Various forms known in the field and the like are applicable, and examples include the following forms.

  The electronic control device is, for example, a variety of electronic components in a protective space (waterproof space or the like) inside the housing formed by joining a plurality of housing members (bottom wall members, peripheral wall members, etc. in the embodiments described later). A circuit board mounted with (semiconductor elements, capacitors, etc.) is accommodated (in a later-described embodiment, a multilayer board structure in which metal substrates and control boards are laminated), and is fixed at a rack shaft accommodating position on the outer peripheral side of the rack housing. Can control the drive of the electric motor.

  Moreover, the material of the said housing | casing can be suitably applied according to the target electric power steering apparatus, for example, the metal material which can be shape-molded in a desired shape is mentioned. The shape of the housing can be appropriately set according to, for example, the shape of the rack shaft accommodation position. When the shape of the rack housing at the rack shaft accommodation position is long in the direction in which the rack shaft extends, a case that is long in the direction in which the rack shaft extends is applied and fixed to the rack housing in a bundle. be able to. As a result, when the rack housing has heat dissipation, it is possible to increase the heat dissipation of the electronic control device in accordance with the contact area of the electronic control device with the rack housing (or the adjacent facing area).

  The fixing structure of the electronic control device may be in any form that can be fixed to the rack housing. For example, a fastening means such as screw fastening is applied, and one end side and the other end of the electronic control device casing in the rack shaft extending direction are applied. And fixing other parts than the one end side and the other end side in the casing.

  The steering mechanism includes, for example, a steering wheel, a steering column (rotary shaft), a gear mechanism, and the like, and has a configuration (rack and pinion) that is connected to the rack shaft via the gear mechanism and can transmit steering torque. Is mentioned. Torque detection means (for example, a rotational torque sensor connected to the steering column) or the like is connected to the steering mechanism, the steering torque by the steering mechanism is detected and transmitted to the electronic control device, and a command signal corresponding to the result is sent. By being configured to transmit to the electric motor, it becomes possible to control the drive of the electric motor according to the steering torque.

  The electric motor is rotationally driven while being driven and controlled by an electronic control device (for example, controlled according to the detection result of the torque detecting means), and the rotation is decelerated via a speed reduction mechanism, and auxiliary torque is applied to the rack shaft. The thing of the structure which can transmit is mentioned. The speed reduction mechanism may be any mechanism as long as it can transmit the auxiliary torque to the rack shaft by reducing the rotation of the electric motor as described above. For example, the structure is connected to the steering column or directly connected to the rack shaft. (For example, it may be connected to a position separated from the gear mechanism of the steering mechanism at a predetermined distance). Further, for example, detection means for detecting the rotation angle, temperature, etc., can be connected to the electric motor, and the driving status of the electric motor can be judged by an electronic control device or appropriately controlled (for example, stop control when an abnormality occurs). You may comprise as follows.

  The rack housing not only accommodates the rack shaft but also constitutes the speed reduction mechanism accommodating portion and the gear mechanism accommodating portion in order to accommodate the speed reduction mechanism and gear mechanism (in addition to various detection means, etc.). Applicable. Each of the speed reduction mechanism accommodating portion and the gear mechanism accommodating portion is formed at a position spaced apart by a predetermined distance in the rack shaft extending direction on the outer peripheral side of the rack housing (a position where an electronic control device can be interposed therebetween). In this case, the electronic control device can be fixed at a position between the speed reduction mechanism housing portion and the gear mechanism housing portion. In this way, the electronic control device is fixed, and furthermore, a power supply connection portion (power supply terminal (phase current terminal), rotation, A signal wiring connector related to the angle detection signal) or a signal wiring connection portion (a signal wiring connector related to the torque detection signal, etc.) for connecting to the torque detection means on the gear mechanism housing side. In such a case, the length of each connection wiring (various wiring such as bus bars and harnesses) can be shortened.

  Further, if at least a part of the connection wiring or the like can be accommodated in the rack housing, the accommodated portion is covered by the rack housing, so that the necessity for improving the waterproofness is reduced, the product cost is suppressed, and the appearance is reduced. It is also possible to improve the performance. Furthermore, when the rack housing has an electromagnetic shielding effect, for example, the influence of noise on various detection signals can be suppressed. Furthermore, in the electronic control device, an inverter comprising a power connector (connector connected to an external power source and receiving power) and the like on the gear mechanism housing portion side, and comprising various semiconductor elements (MOSFETs, etc.) for driving the electric motor. By providing the circuit on the speed reduction mechanism housing part side, a straight line is provided along the rack axis extending direction in the circuit wiring between the portion for receiving and receiving power from the external power source and the portion for supplying power for driving the electric motor. The layout of the circuit wiring structure and various electronic components can be improved, and the increase in size of the electronic control device can be suppressed.

  As a technique for improving the layout, the technical common sense in the circuit wiring technology field can be applied as appropriate. For example, as a housing of an electronic control device, a housing that is formed by joining a plurality of housing members and is long in the rack axis extending direction and can accommodate a circuit board or the like in a protective space inside the housing is applied. As the circuit board, a multilayer board in which a plurality of circuit boards each having a shape that is long in the extending direction of the rack axis and can be accommodated in the housing is applied. Each substrate of the multilayer substrate is fixed at a predetermined distance between the substrates using a support member that extends in the substrate stacking direction, thereby damaging electronic components mounted on the substrates (for example, It is possible to prevent damage due to mutual contact or the like. For example, when a housing member (a peripheral wall member in the embodiments described later) is applied to the housing of the electronic control device, the housing member is used as the support member. Also good.

  Further, in a configuration in which various wirings (signal terminals, etc.) are extended in the substrate stacking direction in order to electrically connect each circuit board, the extended wiring (hereinafter referred to as inter-board wiring) is connected to the substrate. When the location of the wiring connection hole is close to the support member, a guide hole for guiding the inter-substrate wiring to the predetermined wiring connection hole may be formed in the support member. For example, a support member including a gripping portion that grips the outer peripheral edge of the substrate (for example, grips the outer peripheral edge from both side surfaces of the substrate as in the embodiments described later), and one end surface side of the gripping portion A funnel-shaped guide hole drilled in the direction of penetration of the wiring connection hole is formed at a position facing the wiring connection hole. Thereby, when each substrate is stacked, each inter-substrate wiring is guided to a predetermined wiring connection hole by the guide hole, so that it is possible to improve workability related to connection of the inter-substrate wiring. .

  In the connection structure of various connection wirings, common technical knowledge in the connection terminal technical field can be applied as appropriate, and when the phase current terminal of the electronic control device and the electric motor are connected by the phase current bus bar. And connection by a press-fit method. As an example of this, a plurality of sandwiching pieces extending in the bus bar extending direction (long direction) are alternately separated in a stepwise manner in the bus bar thickness direction on the distal end side of the long plate-shaped bus bar. The structure which forms the clamping part formed in parallel, penetrates a terminal in the clamping piece orthogonal direction in the clearance gap between each clamping piece, and connects the bus-bar front-end | tip part and the said terminal in the shape of a net is used.

  As a specific example, on the front end side of the bus bar, two slits extending in the bus bar longitudinal direction are formed (formed in parallel), a portion between the slits, and a peripheral portion between the slits. Are curved so as to be alternately separated in steps with respect to the thickness direction of the bus bar, so that three curved clamping pieces are arranged in parallel (one gripping piece located between the slits and the clamping on the peripheral side between the slits) A sandwiching portion in which two pieces are alternately separated in parallel and formed in parallel is formed. As a result, a gap is formed between the sandwiching pieces, so that the terminals and the like can be passed through the gap in the direction perpendicular to the sandwiching piece. The size of the gap is appropriately set by adjusting the curvature of each clamping piece, for example, the size of the gap so that the terminals penetrating the gap are clamped (alternately clamped) by each clamping piece at a predetermined pressure. By setting, it becomes possible to connect the target terminals by the press-fit method.

  Various detection means for detecting the steering torque (rotation torque) of the steering mechanism, the rotation angle of the electric motor, and the like are not particularly limited as long as each detection target can be detected. For example, the electric power steering device Those known in the field can be applied as appropriate.

  Hereinafter, an example of the electric power steering apparatus according to the present embodiment will be described with reference to the drawings.

<Example of electric power steering system configuration>
First, in the electric power steering apparatus 1 shown in FIGS. 1 and 2, a steering mechanism 2 including a steering wheel 2a, a steering column 2b (and, for example, a shaft coupling 2c if necessary), a gear mechanism 2d, and the like, and a wheel 3a. The shaft extends in the axial direction of the wheel (the shaft is movable in the direction of turning the wheel 3a) and is connected to the steering mechanism 2 via the gear mechanism 2d and transmits the steering torque of the steering mechanism 2 to the wheel 3a. The rack shaft 3, the electric motor 4 that generates the auxiliary torque for assisting the steering torque and transmits the auxiliary torque to the rack shaft 3 through the speed reduction mechanism 4a, the rack shaft 3, the gear mechanism 2d, and the speed reduction mechanism 4a. And an electronic control device 6 that drives and controls the electric motor 4 according to the steering torque of the steering mechanism 2. There.

  The rack housing 5 has a cylindrical shape extending in the axial direction of the rack shaft 3 and a rack shaft housing portion 5a for housing the rack shaft 3 and the like, and is formed on one end side of the rack shaft housing portion 5a to be connected to the gear mechanism 2d and Torque detection means (means for detecting steering torque by the steering mechanism (corresponding to rotation torque by the steering column 2b)) 2e and the like, and a gear mechanism accommodation portion 5b (the gear mechanism accommodation portion) on the other end side of the rack shaft accommodation portion 5a And a speed reduction mechanism accommodating portion 5c which is formed at a position spaced from the distance 5b in the extending direction of the rack shaft 3 and accommodates the speed reduction mechanism 4a, the rotation angle detecting means 4b, and the like. Both ends of the rack shaft 3 are connected to the wheels 3a via, for example, tie rods, knuckle arms or the like (not shown). The gear mechanism 2d has, for example, a pinion shaft (not shown) as an input shaft, and is connected to the rack shaft 3 by a configuration (not shown) in which the pinion teeth of the pinion shaft mesh with the rack teeth of the rack shaft 3. The The speed reduction mechanism 4 a includes various gears, and is connected to the rack shaft 3 so as to transmit the auxiliary torque to the rack shaft 3 by decelerating the rotation of the electric motor 4.

  In the rack housing 5, signal wiring 2f for connecting the electronic control unit 6 and the torque detecting means 2e, and phases for connecting the electronic control unit 6 to the electric motor 4 and the rotation angle detecting means 4b are respectively connected. The current bus bar 4c and the signal wiring 4d are accommodated. In addition, an annular pedestal portion 5d for fixing the electronic control device 6 is formed at a position facing the electronic control device 6 in the rack shaft housing portion 5a. Further, a rack opening 5e is formed inside the annular pedestal 5d in order to connect the signal wires 2f, 4d and the phase current bus bar 4c to the electronic control unit 6 fixed to the annular pedestal 5d. The

<Example of electronic control device>
The electronic control device 6 includes a housing 60 as shown in FIGS. The housing 60 is formed by joining a long flat plate-like bottom wall member 61 and a plurality of columnar bodies (details will be described later) standing on the inner surface of the bottom wall member 61. A cylindrical peripheral wall member 62 that surrounds the four sides of the wall member 61, and has a substantially rectangular shape (in the extending direction of the rack shaft accommodating portion 5 a) that is long in plan view where one side of the peripheral wall member 62 is open. (Long shape). The metal substrate 7 is fixed to the inner side surface of the bottom wall member 61, and the control substrate 8 is supported and fixed at a position on the inner peripheral side surface of the peripheral wall member 62 at a predetermined distance from the metal substrate 7 (in the drawing, the peripheral wall member). 62 is supported and fixed so that the opening on one side of 62 is closed.

  On the outer peripheral side of the bottom wall member 61, a flange portion 61a that is sealed to the annular pedestal portion 5d of the rack shaft accommodating portion 5a is formed to protrude, and a seal member (O-ring or the like) 61e is provided on the flange portion 61a. An annular fitting groove 61b for fitting is formed. In addition, a plurality of semicircular fixing portions 61d (six in the drawing) each having a through hole 61c project from the outer peripheral edge of the flange portion 61a with a predetermined distance therebetween.

  The peripheral wall member 62 is formed by using a plurality of (two columnar bodies 62a, 62b in the present embodiment) having a transverse cross section (cross section in the radial direction of the peripheral wall member 62) U-shaped columnar bodies. Each inner peripheral side surface of 62a, 62b is formed in a cylindrical shape by overlapping and joining in a direction facing each other. A gripping portion 63 for gripping the outer peripheral edge of the control board 8 is formed on one side (opening side) of the inner peripheral surface of the cylindrical peripheral wall member 62.

  In this holding part 63, it protrudes from the inner peripheral side surface of columnar body 62a, 62b, and it engages with the outer periphery of the both end surfaces (the surface by the side of the bottom wall member 61, and the surface by the side of the opening of the peripheral wall member 62) of a control board. A pair of flange portions (U-shaped flange portions) 63a and 63b are provided, and the control substrate 8 can be gripped by fitting the outer peripheral edge of the control substrate 8 between the flange portions 63a and 63b. . For example, as shown in FIG. 5A, the columnar bodies 62a and 62b configured as described above are first fitted between the flange portions 63a and 63b of the gripping portions 63 to the outer peripheral edge of the control board 8, and the columnar bodies 62a. , 62b are joined together to form the peripheral wall member 62 that holds the control board 8, and one end side of the peripheral wall member 62 is fixed to the inner surface of the bottom wall member 61 as shown in FIG. 5B. As a result, the control board 8 is fixed to the peripheral wall member 62 at a position separated from the metal board 7 by a predetermined distance.

  Note that the protruding lengths of the flange portions 63a and 63b of the grip portion 63 can be set so as not to interfere with the inter-substrate wiring or the like. For example, as shown in FIGS. 4 to 6, the protrusion length of the flange portion 63b on the metal substrate 7 side is set longer, the protrusion length of the other flange portion 63a is shortened, and the control substrate 8 of the flange portion 63b is shortened. Even in a configuration in which a funnel-shaped guide hole 63c is formed at a position opposite to the wiring connection hole 8a, the hole being formed in the penetration direction of the wiring connection hole 8a and having an enlarged diameter on the metal substrate 7 side. good. According to such a configuration, when the metal substrate 7 and the control substrate 8 are stacked, each inter-substrate wiring 8b is guided to the predetermined wiring connecting hole 8a by the guide hole 63c, so that the inter-substrate wiring 8b is connected. It is possible to improve the workability related to the above.

  Further, a power connection port (power connector) 64a connected to an external power source (not shown) is provided at one end side (gear mechanism housing portion 5b side) of the outer surface of the bottom wall member 61, and the drive status of the electric power steering device. A connector 64 having an external signal connection port 64b for external signal wiring (not shown) for transmitting the signal to the outside (for example, to transmit to the driver etc. for recognition) or receiving a command signal from the outside is attached. It has been. In the connector 64, the connection ports 64a and 64b divided into two according to the connection destination are integrated via the attachment base 64c, and the connector 64 is connected to the bottom wall member 61 via the attachment base 64c. On the other hand, it is fastened and fixed by a plurality of screws 64d.

  In the electronic control device 6 configured as described above, the flange portion 61a is overlaid on the annular pedestal portion 5d so that the peripheral wall member 62 faces the inside of the rack opening 5e (for example, an O-ring 61e between the joint surfaces). And the screws 61f are passed through the through holes 61c of the respective fixing portions 61d and screwed into the screw holes (not shown) formed in the annular pedestal portion 61d. Thus, the rack shaft receiving portion 5a is fixed. The fixed electronic control unit 6 is connected to signal wirings 2 f and 4 d and a phase current bus bar 4 c housed in the rack housing 5.

<Example of multilayer substrate>
Among the multilayer substrates housed in the electronic control unit 6, the metal substrate 7 includes a long flat plate-like base 70 fixed so as to cover the inner surface of the bottom wall member 61, for example, as shown in FIG. Of the mounting surface 70a of the base portion 70, a power supply circuit board (hereinafter referred to as a power supply board) 71 is fastened and fixed to one end side (the gear mechanism housing portion 5b side) by a screw 70b or the like, and the other end side (the speed reduction mechanism housing portion 5c). An inverter circuit board (hereinafter referred to as an inverter board) 72 is fastened and fixed by screws 70b and the like, and the power supply board 71 and the inverter board 72 are arranged in a straight line.

  For example, as shown in FIG. 8, on the mounting surface 71a of the power supply substrate 71, various capacitors such as an aluminum electrolytic capacitor 73a (four in FIG. 8) and a ceramic capacitor 73b are mounted, and a current detecting shunt resistor. 73c, a circuit protection relay (main relay semiconductor circuit) 73d, a noise filter coil (normal mode choke coil) 73e, a housing ground 73f, and the like are mounted. A plurality of switching elements (MOSFETs, etc.) 74b are mounted on the mounting surface 72a on the one end surface side of the inverter board 72, and an inverter circuit unit 75, a motor relay semiconductor circuit unit are combined by combining these switching elements 74b. 76 etc. are configured.

  The power supply board 71 and the inverter board 72 are electrically connected to each other via a P-side connection part (BATT side) 77a and an N-side connection part (GND side) 77b formed in adjacent parts. Further, a P-side connection portion (BATT side) 77a and an N-side connection portion (GND) for connection to the external power supply side (power connection port 64a side) are also provided at one end side (the gear mechanism housing portion 5b side) of the power supply board 71. Side) 77b is provided. Furthermore, phase current terminals 78 a (U phase), 78 b (V phase), and 78 c (W phase) for connection to the electric motor 4 are provided on the electric motor 4 side of the inverter board 72. These phase current terminals 78a, 78b, 78c may be provided according to the control method of the electric motor 4 (one or two, respectively).

  Further, in the position of the external signal connection port 64b in the metal substrate 7, and in the power supply substrate 71 and the inverter substrate 72, the inter-substrate wiring 8b extending in the direction of the control substrate 8 and connected to the control substrate 8 is desired. It is provided appropriately at the position. Further, a screw hole 79 is formed on the outer peripheral edge of the metal substrate 7.

  The control substrate 8 laminated at a predetermined distance from the metal substrate 7 configured as described above includes, for example, a long flat base 80 as shown in FIG. A conductor pattern (not shown) is formed and a large number of electronic components (not shown) are mounted on the conductor pattern, and supported by the bottom wall member 61 by a peripheral wall member 62. Further, signal wiring connectors 81 and 82 are provided on one end side (the gear mechanism accommodating portion 5b side) and the other end side (the reduction mechanism accommodating portion 5c side) of the control board 8, respectively. A plurality (six in FIG. 10) of screws 79a are passed through the outer peripheral edge of the control board 8 and screwed into the screw holes 79 of the metal board 7, respectively, so that the control board 8 can be fastened and fixed. it can.

  As shown in FIG. 10, when the inter-substrate wiring 8b or the like is connected to the outer peripheral edge of the control board 8, it is necessary to prevent the screw 79a from interfering with the inter-substrate wiring 8b or the like. Although it is difficult to fasten and fix a large number of screws 79a, as long as the outer peripheral edge of the control board 8 is gripped by the gripping portion 63 as in the present embodiment, even if there are few screws. The desired tightening and fixing can be easily performed. Moreover, since the outer peripheral edge of the control board 8 is gripped by the grip portion 63 as described above, the outer peripheral edge is restrained from being curved.

  In the electronic control device 6 including the multilayer substrate formed by laminating the metal substrate 7 and the control substrate 8 as described above, information from the signal wirings 2f and 4d and the external signal wiring is input via the connectors 64, 81 and 82. The drive command signal generated based on the information is output to each switching element 74b and the like of the inverter board 72, whereby each switching element 74b is switched and the electric motor 4 is driven.

<Example of wiring connection structure>
The phase current terminals 78a, 78b, 78c can be connected to a long plate-like phase current bus bar 4c. A pinching portion 91 having a plurality (three in FIG. 11) of pinching pieces 91a, 91b, 91c extending in the longitudinal direction of the bus bar 4c is formed on the front end portion side of the bus bar 4c. . These sandwiching pieces 91a to 91c are curved and arranged in parallel so as to be alternately separated in a stepped manner with respect to the thickness direction of the bus bar 4c. That is, the sandwiching piece 91a located at the center is curved with respect to one of the bus bars 4c in the thickness direction, and the sandwiching pieces 91b and 91c located on both sides of the sandwiching piece 91a are curved with respect to the other in the thickness direction of the bus bar 4c. As a result, a gap is formed between the holding piece 91a and the holding pieces 91b and 91c so that the phase current terminals 78a, 78b, and 78c can pass through in the orthogonal direction of the holding pieces 91a to 91c in the gap. It is configured. Then, by adjusting the bending of each clamping piece 91a to 91c and appropriately setting the size of the gap, the tip of each bus bar 4c is meshed in a press-fit manner with respect to the phase current terminals 78a to 78c. It becomes possible to connect to.

  For example, in the case of the electronic control device 6 (flange portion 61a) fixed as shown in FIG. 1, the phase current terminal 78a with respect to the gap of the sandwiching portion 91 so that the sandwiching portion 91 is positioned at the rack opening 5e. By housing the bus bar 4c in the rack housing 5 so that the through direction of .about.78c is the same as the opening direction of the rack opening 5e, it becomes easy to connect the phase current terminals 78a to 78c and the bus bar 4c. .

  Although the present invention has been described in detail only for the specific examples described above, it is obvious to those skilled in the art that various modifications can be made within the scope of the technical idea of the present invention. It is natural that such changes and the like belong to the scope of the claims.

  For example, the rack housing 5 is not limited to a structure in which the rack shaft housing portion 5a, the gear mechanism housing portion 5b, and the speed reduction mechanism housing portion 5c are integrally formed as shown in FIGS. Any structure can be used as long as the electronic control device 6 can be appropriately fixed in the rack shaft housing portion 5a. As an example, as shown in FIGS. 12 and 13, a rack shaft housing portion 5 a, a gear mechanism housing portion 5 b, and a speed reduction mechanism housing portion 5 c are separately formed and can be assembled and integrated. Can be mentioned.

  The electronic control device 6 is not limited to the structure to which the housing 60 having the bottom wall member 61 is applied as shown in FIGS. 2 to 6, and various electronic components and the like are provided in the protective space inside the housing 60. Any structure can be used as long as it can accommodate a circuit board on which the component is mounted and can be fixed to the rack shaft accommodating portion 5a. As an example, as shown in FIGS. 13 and 14, the bottom wall member 61 is omitted, and a cylindrical peripheral wall member that surrounds the four sides of the metal substrate 7 (at a position separated from the metal substrate 7 by a predetermined distance). A peripheral wall member 62 that supports and fixes the control board 8 or a connector 64 that can be attached to the metal board is applied, and the metal board 7 is directly fixed to the rack shaft accommodating portion 5a. It is done.

  In the structure in which the electronic control unit 6 is fixed to the rack shaft housing portion 5a, the fixing portion 61d of the flange portion 61a of the bottom wall member 61 is screwed and fixed to the rack shaft housing portion 5a as shown in FIGS. It is not limited to the structure, and may be a structure that is bonded and fixed using an adhesive or the like. Further, even in the structure in which the bottom wall member 61 is omitted, as shown in FIGS. 13 and 14, a flange portion 70c and a fixing portion 70d having the same shape as the bottom wall member 61 are formed, and the fixing portion 70d is formed. May be fixed to the rack shaft accommodating portion 5a by screwing, or the metal substrate 7 may be bonded and fixed using an adhesive or the like as described above (for example, the flange portion 70c is bonded and fixed).

  The metal substrate 7 is not limited to a structure in which a plurality of substrates are fixed to the base portion 70 as shown in FIGS. 7 to 9, and may be any structure as long as various electronic components can be mounted. As an example thereof, as shown in FIG. 14, there is a structure in which various electronic components are mounted on the mounting surface 70 a of the metal substrate 7 (a structure in which the power supply substrate 71 and the substrate 72 are integrated with the metal substrate 7).

  Here, technical ideas other than the claims that can be grasped from each of the embodiments described above are listed in the following <a> to <e>.

  <A> The rack housing is formed with a gear mechanism accommodating portion for accommodating the gear mechanism, and the gear mechanism accommodating portion includes a torque detecting means for detecting steering torque by the steering mechanism, the torque detecting means, 2. The electric power steering apparatus according to claim 1, wherein at least a part of connection wiring for electrically connecting the electronic control unit is accommodated.

<B> A support member provided with a gripping part that extends in each substrate stacking direction of the multilayer substrate housed in the electronic control device and grips at least one outer peripheral edge of each substrate from both side surfaces of the substrate. And
The gripping portion is formed in a direction facing the wiring connection hole of the inter-substrate wiring connecting between the substrates in the penetration direction of the wiring connection hole, and a funnel-shaped guide for guiding the inter-substrate wiring to the wiring connection hole. The electric power steering apparatus according to claim 1, further comprising a hole.

<C> In the rack housing, a speed reduction mechanism accommodating portion that accommodates the speed reduction mechanism and a gear mechanism accommodating portion that accommodates the gear mechanism are formed at positions spaced apart from each other in the rack shaft extending direction. The electronic control device is fixed to the outer peripheral side of the rack housing at a position between the gear mechanism housing portion,
In the electronic control device, a power supply connection portion that is electrically connected to the electric motor is provided at an end portion on the speed reduction mechanism housing portion side, and a signal that is connected to the torque detection means is disposed on an end portion on the gear mechanism housing portion side. The electric power steering apparatus according to claim 1, further comprising a wiring connection portion.

  <D> In the electronic control device, a power connector connected to an external power source is provided on the gear mechanism housing portion side, and an inverter circuit for driving the electric motor is provided on the speed reduction mechanism housing portion side. The electric power steering apparatus as described in <C> above.

<E> A plate-shaped bus bar is interposed between the electric motor and the power supply connecting portion,
The front end portion of the bus bar is provided with a plurality of sandwiching pieces extending in the bus bar extending direction, and each of the sandwiching pieces is alternately curved in a stepwise manner in the bus bar thickness direction and separated. Are formed in parallel,
The electric power steering apparatus according to <C>, wherein the power supply connecting portion is connected through the gap between the holding pieces in a direction orthogonal to the holding pieces.

DESCRIPTION OF SYMBOLS 1 ... Electric power steering apparatus 2 ... Steering mechanism 3 ... Rack shaft 4 ... Electric motor 5 ... Rack housing 6 ... Electronic control unit 61 ... Bottom wall member 62 ... Peripheral wall member 63 ... Gripping part 63c ... Guide hole 91 ... Clamping part 91a- 91c ... clamping piece

Claims (3)

An electric power steering device for assisting steering of a steering mechanism with an auxiliary torque by an electric motor,
A rack shaft connected to the steering mechanism via a gear mechanism and transmitting the steering torque of the steering mechanism to the wheels; a speed reducing mechanism for decelerating the rotation of the electric motor and transmitting auxiliary torque to the rack shaft; and the rack shaft A rack housing that houses the speed reduction mechanism, and an electronic control device that controls the drive of the electric motor,
The electric power steering apparatus, wherein the electric motor is fixed at a speed reduction mechanism accommodation position in the rack housing, and the electronic control unit is fixed at a rack shaft accommodation position on an outer peripheral side of the rack housing.   2. The electric power steering apparatus according to claim 1, wherein the electronic control device is fixed to the rack housing at least on one end side and the other end side in the rack shaft extending direction of the electronic control device. .   The rack housing is formed with a speed reduction mechanism accommodating portion for accommodating the speed reduction mechanism, and at least a part of connection wiring for electrically connecting the electronic control unit and the electric motor is accommodated in the speed reduction mechanism accommodating portion. The electric power steering apparatus according to claim 1, wherein

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