JP2009137479A - Electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the electric power steering device which prevents temperature rise in a control unit. <P>SOLUTION: In the electric power steering device 10, a warm wheel 18 and a warm gear 19 which connect a motor 30 and a steering shaft 11 are accommodated in a gear housing 40 made of aluminum. The control unit 20 for controlling the motor 30 is formed by covering an inverter circuit board 25 with a board case 23. In the state in which one side surface of the board case 23 is opened, its opening port 23K is closed by the inverter circuit board 25, and the inverter circuit board 25 is brought into contact a component mounting surface 45F formed on the gear housing 40, the control unit 20 is fixed to the gear housing 40. Thereby, the heat of the inverter circuit board 25 can be efficiently discharged into the gear housing 40, thus preventing the temperature rise in the control unit 20. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electric power steering apparatus in which a motor is connected to a tearing shaft that rotates integrally with a handle via a gear, and assist torque is applied from the motor to a steering shaft in accordance with driving conditions.

Conventionally, in this type of electric power steering apparatus, a control unit for driving and controlling a motor as a drive source is fixed to the outer wall of the motor. And the heat of the control unit was released to the outer wall of the motor (so-called motor housing) (for example, see Patent Document 1).
JP-A-11-115775 (Claim 1, FIG. 1)

  However, since the motor generates heat together with the control unit when the motor is driven, the conventional electric power steering apparatus described above cannot efficiently exhaust heat from the control unit, and the control unit becomes hot and the durability is lowered. It was the cause.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an electric power steering apparatus capable of preventing a control unit from being heated to a high temperature.

  In order to achieve the above object, an electric power steering apparatus (10) according to the invention of claim 1 includes a steering shaft (11) rotating integrally with a handle (88), and a gear (18) on the steering shaft (11). , 19) and the brushless motor (30) connected to each other through the gear shaft (18, 19), the steering shaft (11) penetrates, and the stator (30A) of the brushless motor (30) is fixed to the outer surface. An aluminum gear housing (40), and a control unit (20) in which an inverter circuit board (25) for generating a motor drive current to the brushless motor (30) is covered with a board case (23). An electric power steering device that assists the steering of the handle (88) by the output of the brushless motor (30) ( 0), one side surface of the substrate case (23) is opened, the opening (23K) is closed with the inverter circuit board (25), and the circuit mounting surface of the inverter circuit board (25) is covered with the substrate case ( 23), the control unit (20) is fixed to the gear housing (40) by bringing the non-mounting surface on the back side of the circuit mounting surface into contact with the flat surface (45F) formed on the gear housing (40). However, it has characteristics.

  In addition, grease or a plate material is attached or attached to the “non-mounting surface of the inverter circuit board (25)” and the “flat surface (45F) of the gear housing (40)”, and the inverter circuit board (25) When the non-mounting surface and the flat surface (45F) of the gear housing (40) are brought into contact with each other, the non-mounting surface of the inverter circuit board (25) and the flat surface (45F) of the gear housing (40) in the present invention are also used. Included in contact.

  According to a second aspect of the present invention, in the electric power steering device (10) according to the first aspect, the gear housing (40) is an aluminum casting, and a control unit is provided on a common component mounting surface (45F) machined into the aluminum casting. It is characterized in that (20) and the brushless motor (30) are attached together.

  According to a third aspect of the present invention, in the electric power steering device (10) according to the second aspect, the brushless motor (30) and the control unit (20) are provided with a plurality of projecting piece-like shapes parallel to the component mounting surface (45F). Terminal fittings (26A to 26C, 33A to 33C) are provided to form through holes in each of the terminal fittings (26A to 26C, 33A to 33C), and either the brushless motor (30) or the control unit (20). On one side, a terminal block (31) for supporting a plurality of terminal fittings (33A to 33C) from the component mounting surface (45F) side is provided, and each terminal fitting (26A to 26C) of the brushless motor (30) and the control unit (20) is provided. , 33A to 33C) are characterized in that a screw which is overlapped and passed through is fastened to a female screw hole formed in the terminal block (31).

  According to a fourth aspect of the present invention, in the electric power steering apparatus (10) according to any one of the first to third aspects, the control unit (20) determines the target value of the motor drive current in accordance with the driving situation. The control circuit board (24) is provided, and the control circuit board (24) is characterized in that it is held upright with respect to the inverter circuit board (25) by the board case (23).

  The invention of claim 5 is the electric power steering device (10) according to any one of claims 1 to 4, wherein the inverter circuit board (25) is formed by mounting the inverter circuit (25C) on a metal board. Has characteristics.

[Invention of Claim 1]
In the electric power steering apparatus according to the first aspect, since the inverter circuit board that is a heat source in the control unit is brought into contact with the aluminum gear housing that is not the heat source, heat is efficiently discharged from the control unit as compared with the conventional case. be able to. Thereby, the high temperature of the control unit can be prevented and the durability can be improved.

[Invention of claim 2]
According to the configuration of the second aspect, since the control unit and the brushless motor are mounted on the common component mounting surface, the gear which is an aluminum casting is compared with the case where the control unit and the brushless motor are mounted on separate component mounting surfaces. It is possible to reduce the machining process of the component mounting surface with respect to the housing, and to reduce the machining cost.

[Invention of claim 3]
According to the configuration of the third aspect, since the terminal fittings of the brushless motor and the control unit are overlapped with each other and fastened with screws to the terminal block, a cable for connecting the brushless motor and the control unit becomes unnecessary. .

[Invention of claim 4]
According to the configuration of claim 4, since the control circuit board is in an upright state with respect to the inverter circuit board, the control circuit board and the inverter circuit board are arranged between the boards as in the case where they are arranged in parallel. Heat will not be trapped.

[Invention of claim 5]
According to the configuration of claim 5, since the inverter circuit board is formed by mounting the inverter circuit on the metal board, the inverter circuit board is connected to the gear housing as compared with a case where a normal board made of a non-metallic member is used. Can be efficiently exhausted.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a vehicle 81 equipped with an electric power steering apparatus 10 according to the present invention. A rack 83 is passed between the pair of steered wheels 82, 82 in the vehicle 81, and the rack 83 is inserted into a cylindrical rack case 85. Both ends of the rack 83 are connected to the steered wheels 82 and 82 via tie rods 83T and 83T, and the rack case 85 is fixed to the main body of the vehicle 81. A vehicle speed sensor 84 for detecting the vehicle speed based on the rotation of the steered wheel 82 is provided in the vicinity of the steered wheel 82.

  The rack 83 is meshed with a pinion 86 that penetrates the intermediate portion of the rack case 85 from the side. A plurality of steering shafts 11, 110, 111 are arranged in a line between the pinion 86 and the handle 88 and are connected to each other by a universal joint (universal joint) (not shown). The steering shafts 11, 110, and 111 transmit the rotation of the handle 88 to the pinion 86.

  The electric power steering apparatus 10 of the present embodiment supports the steering shaft 11 on the handle 88 side among the plurality of steering shafts 11, 110, 111 so as to be rotatable by the shaft support housing 13 shown in FIG. An assist torque can be applied to the steering shaft 11 from a brushless motor 30 (hereinafter simply referred to as “motor 30”) assembled to the support housing 13.

  Specifically, the shaft support housing 13 is configured by assembling a gear housing 40 to the lower end portion of the expandable sleeve 12 formed of a cylindrical tube. The expansion / contraction sleeve 12 is formed by inserting a second sleeve 12B having a relatively small diameter inside the lower end of the first sleeve 12A having a relatively large diameter, and the entire expansion / contraction sleeve 12 is expanded and contracted by changing the insertion amount.

  In contrast, the steering shaft 11 extends and contracts between the first shaft 11A housed on the upper end side of the shaft support housing 13 and the second shaft 11B housed on the lower end side of the shaft support housing 13 (not shown). It is connected by a mechanism. The shaft expansion / contraction mechanism has a structure in which, for example, the lower end portion of the first shaft 11A is formed in a cylindrical shape, and the upper end portion of the second shaft 11B is splined to the inside thereof. Thus, the first and second shafts 11A and 11B are coupled so as to be integrally rotatable and linearly movable. The first shaft 11A is rotatably supported by a bearing (not shown) on the first sleeve 12A, while the second shaft 11B is rotated by a bearing (not shown) on the second sleeve 12B. It is pivotally supported. Thereby, the steering shaft 11 expands and contracts together with the expansion sleeve 12.

  An upper end portion of the first shaft 11A protrudes upward from the first sleeve 12A, and a handle 88 is attached to the protruding portion so as to be integrally rotatable. On the other hand, the lower end portion of the second shaft 11B protrudes downward from the second sleeve 12B, and another steering shaft 110 (see FIG. 1) is connected thereto via a universal joint (not shown).

  The gear housing 40 is, for example, an aluminum casting, and as shown in FIG. 4, a disc-shaped worm wheel housing portion 41 centering on the steering shaft 11 and a cylindrical worm gear housing tube disposed on the peripheral portion thereof. The unit 42 is integrally formed. As shown in FIG. 2, the steering shaft 11 passes through the central portion of the worm wheel housing portion 41, and the worm wheel 18 fixed to the steering shaft 11 so as to be integrally rotatable is housed in the worm wheel housing portion 41. Yes. A worm gear 19 (see FIG. 1) meshed with the worm wheel 18 is housed inside the worm gear housing tube portion 42 and is rotatably supported by a bearing (not shown).

  As shown in FIG. 2, a torque sensor housing portion 44 having a smaller diameter than the worm wheel housing portion 41 protrudes from the center of the upper end surface of the worm wheel housing portion 41. A torque sensor 44S (see FIGS. 1 and 8) for detection is accommodated. Note that the second sleeve 12 </ b> B is fixed to the upper end portion of the torque sensor housing portion 44.

  A pair of bracket connecting portions 43 and 43 (see FIG. 4) are provided on the surface of the gear housing 40 facing away from the surface from which the torque sensor accommodating portion 44 protrudes. As shown in FIG. 4, the bracket connecting portions 43 and 43 are orthogonal to the axial direction of the worm wheel accommodating portion 41 and the axial direction of the worm gear accommodating cylindrical portion 42 (hereinafter, this direction is referred to as “the gear housing 40. In the horizontal direction). A pair of support arms 53 and 53 provided in a fixed bracket 50 described below are rotatably connected to the bracket connecting portions 43 and 43.

  The fixed bracket 50 is a sheet metal part. As shown in FIG. 2, the pair of support arms 53 and 53 shown in FIG. 5 are protruded downward from the main body 52 arranged opposite to the side of the telescopic sleeve 12. It has a structure. The pair of support arms 53 and 53 are rotatably connected to the bracket connecting portions 43 and 43 of the gear housing 40 as described above. Further, the support arms 53, 53 extend along the axial direction of the worm gear accommodating cylinder portion 42 to the side farther from the telescopic sleeve 12 than the main portion 52, and protrude to the side of the gear housing 40. Further, the tips of the support arms 53, 53 protruding from the gear housing 40 are bent at right angles to the sides away from each other to form lower end fixing portions 55, 55. And the upper end fixing | fixed part 56 with which the main-body part 52 was equipped, and the lower end fixing | fixed parts 55 and 55 are being fixed to the vehicle main body with the volt | bolt.

  As shown in FIG. 2, a slide rail 51 is attached to a surface of the main body 52 of the fixed bracket 50 facing the expansion sleeve 12 in parallel with the expansion sleeve 12. The slider 14 is slidably engaged with the slide rail 51, and the slider 14 is fixed to the first sleeve 12A. Thereby, when the shaft support housing 13 is rotated with respect to the fixed bracket 50 around the bracket connecting portion 43 of the gear housing 40, the expansion / contraction sleeve 12 expands and contracts, and the slider 14 moves relative to the slide rail 51. Slide.

  The slider 14 is provided with a rotation lever 15 so as to be rotatable. The rotating lever 15 is biased to the origin position by a torsion spring 54. When the rotation lever 15 is disposed at the origin position, an engagement mechanism (not shown) provided in the slider 14 is engaged, and the slider 14 is fixed to the slide rail 51. As a result, the shaft support housing 13 cannot be rotated with respect to the fixed bracket 50 in a state where the rotation lever 15 is disposed at the origin position.

  On the other hand, when the rotation lever 15 is rotated to a position away from the origin position, the engagement mechanism is disengaged and the slider 14 can slide with respect to the slide rail 51. Thereby, when the rotation lever 15 is separated from the origin position, the shaft support housing 13 can be rotated with respect to the fixed bracket 50. In other words, the shaft angle of the handle 88 with respect to the vehicle body (rotation shaft angle) can be changed to an angle that suits the driver's preference. In addition, when the shaft angle of the handle 88 is changed, the connection angle by the universal joint between the steering shafts 11, 110, and 111 changes accordingly.

  Now, a flat component fixing plate 45 is integrally formed at one end of the worm gear accommodating cylinder portion 42 and is disposed between the support arms 53 and 53 of the fixing bracket 50. Further, as shown in FIG. 3, the component fixing plate 45 is sized so as to cover the entire worm wheel housing part 41 from one side, and as shown in FIG. It is united.

  As shown in FIG. 5, the surface of the component fixing plate 45 facing the opposite side of the worm wheel housing portion 41 and the worm gear housing tube portion 42 is a component mounting surface 45F according to the present invention. The component mounting surface 45F is formed by, for example, milling the gear housing 40, which is an aluminum casting, and is a flat surface orthogonal to the central axis of the worm gear housing cylinder portion 42. As shown in FIG. 2, reinforcing ribs 41 </ b> L and 41 </ b> L are formed at corners of the component fixing plate 45 where the surface opposite to the component mounting surface 45 </ b> F and the both end surfaces of the worm wheel accommodating portion 41 are orthogonal to each other. Has been.

  As shown in FIG. 4, a brushless motor 30 (hereinafter simply referred to as “motor 30”) is attached to an end of the component attachment surface 45 </ b> F on the worm gear housing cylinder portion 42 side. As shown in FIG. 5, the motor 30 includes a rotation output shaft 30 </ b> B protruding from the center of one end surface of the columnar stator 30 </ b> A. In addition, a pair of motor fixing portions 34, 34 project in opposite directions from one end portion of the outer peripheral surface of the stator 30A, and screw insertion holes 34N are formed through the motor fixing portions 34, respectively.

  On the other hand, the edge of the component fixing plate 45 on the worm gear housing cylinder part 42 side is curved in a semicircular shape centering on the worm gear housing cylinder part 42, and a pair of sides is formed from both ends of the curved surface. The bolt fixing portions 45B and 45B are overhanging. Further, a communication hole 46A communicating with the internal space of the worm gear housing cylinder portion 42 is formed on the central axis of the worm gear housing cylinder portion 42 of the component fixing plate 45, and female screw holes are formed in the bolt fixing portions 45B and 45B. 46B and 46B are formed through. Then, the rotation output shaft 30B of the motor 30 is inserted into the communication hole 46A, and for example, key-coupled (or spline-coupled) to the worm gear 19 (see FIG. 1) in the worm gear housing cylinder portion 42, and the motor 30 With one end surface of the stator 30 </ b> A being in surface contact with the component mounting surface 45 </ b> F of the component fixing plate 45, a screw (not shown) inserted into each screw insertion hole 34 </ b> N of the motor 30 is inserted into each female of the component fixing plate 45. The stator 30 </ b> A of the motor 30 is fixed to the component fixing plate 45 by being fastened to the screw hole 46 </ b> B.

  The motor 30 includes three-phase windings of U, V, and W, and terminal fittings 33A to 33C connected to the ends of these windings protrude from the side surface of the stator 30A as shown in FIG. ing. In addition, the side surface of the stator 30A is integrally provided with a terminal block 31 for supporting the terminal fittings 33A to 33C. Specifically, the terminal block 31 has a lower surface that is flush with the end surface of the stator 30A from which the rotation output shaft 30B protrudes, and comes into surface contact with the component mounting surface 45F, and the upper surface has a stepped shape with three steps. ing. Terminal fittings 33A, 33B, and 33C are placed on the upper surface of each stage of the terminal block 31, respectively. In addition, through holes are formed in the terminal fittings 33A to 33C, and female screw holes are formed in the terminal block 31 at positions facing the through holes of the terminal fittings 33A to 33C. And the terminal block 31 is arrange | positioned in the center part of the component attachment surface 45F in the state in which the motor 30 was fixed to the component fixing plate 45. FIG.

  As shown in FIG. 4, the control unit 20 is attached to the component attachment surface 45 </ b> F so as to be adjacent to the motor 30. As shown in FIG. 6, the control unit 20 includes a control circuit board 24, an inverter circuit board 25, and a harness 26, and has a structure in which they are covered with a board case 23.

  The control circuit board 24 mounts the control circuit 24C shown in FIG. 8, and determines the target value of the motor drive current according to the driving situation. Specifically, on the control circuit board 24, a CPU 29, electrolytic capacitors C1 to C3, connectors CN3 to CN5, and the like constituting the control circuit 24C are mounted.

  The connectors CN4 and CN5 are connected to the vehicle speed sensor 84 and the torque sensor 44S, and the detection signals of the vehicle speed sensor 84 and the torque sensor 44S are taken into the CPU 29. The vehicle speed sensor 84 and the connector CN4 are connected via an in-vehicle LAN in which data communication by CAN is performed. Then, the CPU 29 determines the target value of the motor drive current for the motor 30 so that the steering of the handle 88 is light when the vehicle is stopped or when traveling at low speed, and the steering of the handle 88 is heavy when traveling at medium or high speed. Further, a battery BT mounted on the vehicle 81 (see FIG. 1) is connected to the connector CN2. The output of the battery BT is smoothed by the electrolytic capacitors C1 to C3 and is supplied to electronic components such as the CPU 29 on the control circuit board 24.

  On the other hand, the inverter circuit board 25 is formed by mounting the inverter circuit 25C shown in FIG. 8 on a metal board, for example, and generates a motor drive current corresponding to the target value determined by the control circuit board 24. Specifically, on the inverter circuit board 25, switch elements UH, VH, WH, UL, VL, WL, phase direction relays SW1, SW2, a connector CN1, and the like constituting the inverter circuit 25C are mounted so as to cover them. A harness 26 is arranged and fixed. The harness 26 has a structure in which a conductive member 26P (for example, a bus bar) is fixed by a support member 26J made of an insulating resin. The switch elements UH, VH, WH, UL, VL, WL, and the like are connected by the harness 26 by the conductive member 26P to form an inverter circuit 25C.

  The switch elements UH, VH, WH, UL, VL, WL are, for example, N-channel type MOSFETs, and the gates of these MOSFETs are the connector CN3 of the control circuit board 24 and the connector CN1 of the inverter circuit board 25, and these It is connected to the CPU 29 of the control circuit 24C via a cable between the connectors CN1 and CN3. Further, the output of the battery BT smoothed by the electrolytic capacitors C1 to C3 is drawn into the inverter circuit board 25 through the connectors CN1 and CN3 and a cable.

  The inverter circuit 25C is a three-phase bridge circuit having U, V, W phase circuits 28U, 28V, 28W connected in parallel between the positive electrode of the battery BT and the negative electrode having the same potential as GND. . The switch elements UH, VH, WH are arranged on the upper side of the phase circuits 28U, 28V, 28W, while the switch elements UL, VL, WL are arranged on the lower side of the phase circuits 28U, 28V, 28W. Is provided. Further, terminal fittings 26A, 26B, and 26C are connected to the ends of three output lines extending from between the upper and lower switch elements in the U, V, and W phase circuits 28U, 28V, and 28W. Then, the inverter circuit 25C turns on and off the switch elements UH, VH, WH, UL, VL, WL in a predetermined combination, and outputs the DC output of the battery BT as a three-phase alternating current. The phase direction relays SW1 and SW2 are respectively provided in the middle of the U and V output lines among the three output lines of the inverter circuit 25C.

  The terminal fittings 26A, 26B, and 26C described above protrude laterally from the side surface of the support member 26J in the harness 26, and are arranged in a step-like manner, like the terminal fittings 33A, 33B, and 33C of the motor 30. Yes. In addition, through holes are also formed at the distal ends of the terminal fittings 26A, 26B, and 26C, similarly to the terminal fittings 33A, 33B, and 33C of the motor 30.

  The control circuit board 24 and the inverter circuit board 25 have a circuit mounting surface on which only one of the front and back surfaces is mounted, and the other surface is a flat non-mounting surface on which no circuit is mounted. ing.

  As shown in FIG. 6, the substrate case 23 is formed by assembling a sheet metal cover body 21 to a resin case body 22. The case main body 22 has a shape obtained by combining the first and second casing portions 60 and 65 each having a flat box shape into an L shape. Specifically, the first housing unit 60 includes a square control board facing wall 61 that faces the circuit mounting surface of the control circuit board 24, and the side wall 62 projects from the edge of the control board facing wall 61, The surface facing the substrate facing wall 61 is open. Then, the control circuit board 24 is fixed (for example, screwed) to the case body 22 in a state where the front end of the side wall 62 is abutted against the edge of the circuit mounting surface of the control circuit board 24, thereby the first housing part 60. Of these, the surface facing the control substrate facing wall 61 is closed. A rectangular bulging portion 61 </ b> R bulging outward is formed at a position near the corner portion of the control substrate facing wall 61 on the side intersecting the second housing portion 65.

  The second housing portion 65 protrudes from the one side edge portion of the control substrate facing wall 61 of the first housing portion 60 to the opposite side of the control circuit board 24, whereby the entire case body 22 is L-shaped. . And the side part provided with the 2nd housing | casing part 65 among the 1st housing | casing parts 60 is arrange | positioned at the component attachment surface 45F side, and the board | substrate with the control board opposing wall 61 standing upright at right angles from the component attachment surface 45F is carried out. The case 23 is fixed to the component fixing plate 45 (see FIG. 4).

  The second casing 65 extends from the control board facing wall 61 at a right angle and is parallel to the component mounting surface 45F. The mounting surface facing wall 66 extends from the edge of the mounting surface facing wall 66 toward the component mounting surface 45F. And a side wall 67 that protrudes. Moreover, the 2nd housing | casing part 65 is a little shorter than the full length of the one side edge part of the 1st housing | casing part 60 from which the 2nd housing | casing part 65 protruded. Further, the entire surface of the second housing portion 65 on the component mounting surface 45F side is open, and the front end surface of the side wall 67 is parallel to the component mounting surface 45F. As shown in FIG. 7, the first housing part 60 and the second housing part 65 communicate with each other inside, and an L-shaped space is formed inside the case main body 22. Note that a rectangular bulging portion 66R that protrudes outward is formed in a portion of the mounting surface facing wall 66 that intersects the bulging portion 61R. In addition, bolt insertion holes 65 </ b> Z for inserting bolts are formed at the four corners of the mounting surface facing wall 66.

  In addition, the outer surface of the side wall 62 on the component mounting surface 45 </ b> F side of the first housing portion 60 is flush with the front end surface of the side wall 67. Furthermore, a part of the side wall 62 on the component attachment surface 45F side in the first housing part 60 is cut out and opened with the same width as the opening on the component attachment surface 45F side in the second housing part 65. That is, a substantially rectangular opening 23 </ b> K is formed on the surface of the board case 23 that faces the component mounting surface 45 </ b> F so as to straddle the first housing portion 60 and the second housing portion 65. The inverter circuit board 25 is fixed to the case body 22 with the edge of the opening 23K in the board case 23 abutting on the edge of the circuit mounting surface, and the opening 23K is closed. Note that a cable (not shown) for connecting the connector CN1 of the inverter circuit board 25 and the connector CN3 of the control circuit board 24 is accommodated in the case body 22.

  As shown in FIG. 6, a connector exposure hole 60A is formed in one side wall 62 of the pair of side walls 62 standing upright from the component mounting surface 45F in the first housing portion 60. As shown in FIG. 3, the connectors CN2, CN4, and CN5 mounted on the control circuit board 24 are exposed to the outside through the connector exposure holes 60A. Further, as shown in FIG. 6, a terminal exposure hole 65A is formed in the side wall 67 of the second casing portion 65 on the side away from the first casing portion 60, and the terminal fitting 26A is formed from the terminal exposure hole 65A. , 26B, 26C project outside the case body 22.

  The cover body 21 has a box shape that is fitted to the outside of the side wall 62 in the first housing portion 60 and covers the control circuit board 24 from the opposite side of the control board facing wall 61. A side opening 21 </ b> B corresponding to the connector exposure hole 60 </ b> A of the first housing part 60 is formed on the sheet metal side wall 21 </ b> S fitted to the first housing part 60 in the cover body 21. Further, a plurality of bending locking pieces 21A protrude from the front end of the sheet metal side wall 21S, and the cover body 21 is fixed to the case main body 22 by bending the bending locking pieces 21A onto the outer surface of the control substrate facing wall 61. ing. Further, the surface of the cover body 21 facing the component mounting surface 45F side is open.

  The control unit 20 has bolts inserted through bolt insertion holes 65Z (see FIG. 6) at the four corners of the second housing portion 65 with the non-mounting surface of the inverter circuit board 25 in contact with the component mounting surface 45F. The component fixing plate 45 is fastened to a screw hole (not shown) and fixed. It is preferable to apply high thermal conductivity grease between the non-mounting surface of the inverter circuit board 25 and the component mounting surface 45F. Then, the terminal fittings 26A, 26B, and 26C of the control unit 20 are overlaid on the terminal fittings 33A, 33B, and 33C of the motor 30, respectively, and the screw that penetrates the overlapping terminal fittings 26A, 33A, etc. The control unit 20 and the motor 30 are connected by being tightened in the screw holes. Thereby, the cable for connecting between the motor 30 and the control unit 20 becomes unnecessary, and the electric power steering apparatus 10 as a whole has a compact configuration. In the present embodiment, since the control unit 20 and the motor 30 are mounted on the common component mounting surface 45F in the gear housing 40, compared to the case where the control unit 20 and the motor 30 are mounted on separate component mounting surfaces, The machining process of the component mounting surface 45F with respect to the gear housing 40 can be reduced, and the machining cost can be reduced.

  In addition, in the control unit 20 of this embodiment, in the state attached to the vehicle 81, the component attachment surface 45F will be in the state which faced diagonally downward with respect to the perpendicular direction. The electric circuit is no longer located below the electrolytic capacitors C1 to C3 in the control circuit board 24. As a result, even if a liquid leaks from the electrolytic capacitors C1 to C3, it is possible to prevent the electric circuit (particularly the power line) from being short-circuited by the liquid.

  The description regarding the configuration of the electric power steering apparatus 10 of the present embodiment has been described above. Next, the function and effect of the electric power steering apparatus 10 will be described. When the vehicle 81 stops and travels at a low speed, the motor drive current is applied from the inverter circuit board 25 to the motor 30 with more opportunities for the steering angle of the handle 88 to be larger than when traveling at a medium or high speed. Specifically, when the steering wheel 88 is frequently turned to the left and right when the vehicle 81 is stopped at a low speed while traveling at a low speed, a current is passed continuously or at short intervals from the inverter circuit board 25 to the motor 30. The motor 30 and the control unit 20 generate heat. In particular, when the vehicle 81 is stopped and the steering wheel 88 is turned off, so-called stationary, the road surface resistance increases, so that a relatively large current flows from the inverter circuit board 25 to the motor 30, and the motor 30 and the control unit. The temperature of 20 increases. In the control unit 20, the amount of heat generated by each FET as the switch elements UH, VH, WH, UL, VL, WL provided in the inverter circuit 25C increases, and the entire inverter circuit board 25 on which the inverter circuit 25C is mounted is provided. The temperature rises.

  However, in the electric power steering apparatus 10 of the present embodiment, the inverter circuit board 25 that is a heat source in the control unit 20 is brought into contact with the aluminum gear housing 40 that is not a heat source, so that the control is performed more efficiently than in the past. Heat can be discharged from the unit 20. Further, since the inverter circuit board 25 is formed by mounting the inverter circuit 25C on a metal board, the inverter circuit board 25 is discharged from the inverter circuit board 25 to the gear housing 40 as compared with the case where a normal board made of a non-metal member is used. Heat can be efficiently performed. Furthermore, in the control unit 20, the control circuit board 24 is in an upright state with respect to the inverter circuit board 25, so that the board 24 is arranged as if the control circuit board 24 and the inverter circuit board 25 are arranged in parallel. , 25 does not collect heat between them. As a result, in the electric power steering apparatus 10 according to the present embodiment, the control unit 20 can be prevented from being heated at high temperatures, and the durability can be improved.

[Other Embodiments]
The present invention is not limited to the above-described embodiment. For example, the embodiments described below are also included in the technical scope of the present invention, and various other than the following can be made without departing from the scope of the invention. It can be changed and implemented.

  (1) In the electric power steering apparatus 10 of the above embodiment, the motor 30 is connected to the steering shaft 11 via the worm wheel 18 and the worm gear 19, but the gear connecting the motor 30 and the steering shaft 11 is the worm. It is not limited to the wheel 18 and the worm gear 19, and may be a flat gear or a bevel gear, for example.

  (2) In the above embodiment, the control circuit board 24 is arranged orthogonal to the inverter circuit board 25. However, the control circuit board 24 and the inverter circuit board 25 may be arranged in parallel.

  (3) In the above embodiment, the terminal fittings 26A to 26C of the control unit 20 and the brushless motor 30 terminal fittings 33A to 33C are both attached to the terminal block 31 and are conductively connected. , 33A to 33C may be connected to each other by welding. In addition, the form of welding may be any one of butting and welding, overlapping in the vertical direction and welding in the horizontal direction.

  (4) In the above embodiment, the component mounting surface 45F of the gear housing 40 is a processed surface, but may be a cast surface.

  (5) In the embodiment, the control circuit board 24 is screwed to the case body 22 among the case body 22 and the cover body 21 constituting the board case 23, but the control circuit board 24 is screwed to the cover body 21. May be. Further, the cover body 21 is fixed to the case main body 22 by the bending locking piece 21 </ b> A. It may be tightened together.

The conceptual diagram of the vehicle carrying the electric power steering device which concerns on one Embodiment of this invention. Partially cutaway side view of an electric power steering device Side view of electric power steering device Perspective view of electric power steering device The perspective view of the electric power steering device with the control unit and the motor removed from the gear housing Exploded perspective view of control unit Exploded perspective view of control unit Circuit diagram of the circuit of the control unit

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electric power steering apparatus 11 Steering shaft 18 Worm wheel 19 Worm gear 20 Control unit 23 Substrate case 23K Opening port 24 Control circuit board 24C Control circuit 25 Inverter circuit board 25C Inverter circuits 26A-26C, 33A-33C Terminal fitting 30 Brushless motor 30A Stator 31 Terminal block 40 Gear housing 45F Component mounting surface 88 Handle

Claims (5)

A steering shaft that rotates integrally with the handle;
A brushless motor connected to the steering shaft via a gear;
An aluminum gear housing that houses the gear and through which the steering shaft passes, and in which the stator of the brushless motor is fixed to the outer surface;
An electric power steering apparatus comprising: a control unit configured to cover an inverter circuit board for generating a motor driving current to the brushless motor with a board case; and assisting steering of the handle by an output of the brushless motor.
Opening one side of the substrate case and closing the opening with the inverter circuit board, while turning the circuit mounting surface of the inverter circuit board to the inside of the substrate case, on the back side of the circuit mounting surface An electric power steering apparatus, wherein a non-mounting surface is brought into contact with a flat surface formed on the gear housing, and the control unit is fixed to the gear housing.   2. The electric power steering apparatus according to claim 1, wherein the gear housing is an aluminum casting, and the control unit and the brushless motor are both attached to a common component mounting surface processed into the aluminum casting. The brushless motor and the control unit are each provided with a plurality of protruding piece-like terminal fittings parallel to the component mounting surface, and through holes are formed in each of the terminal fittings, and any one of the brushless motor and the control unit On one side, a terminal block that supports the plurality of terminal fittings from the component mounting surface side is provided,
The electric power steering apparatus according to claim 2, wherein a screw in which the terminal fittings of the brushless motor and the control unit are overlapped and passed through is tightened in a female screw hole formed in the terminal block. .   The control unit is provided with a control circuit board for determining a target value of the motor drive current according to an operation situation, and the control circuit board is in an upright state with respect to the inverter circuit board by the board case The electric power steering device according to any one of claims 1 to 3, wherein the electric power steering device is held by the motor.   5. The electric power steering apparatus according to claim 1, wherein the inverter circuit board is formed by mounting an inverter circuit on a metal board.