Vehicular steering device

Abstract

This vehicular steering device (10) includes a motor (30) and a transmission mechanism (40). The motor (30) includes a motor housing (31). The transmission mechanism (40) includes a mechanism housing (41). A mechanism-side fitting section (41d) of the mechanism housing (41) and a motor-side fitting section (31d) of the motor housing (31) are arranged outward in the radial direction of a rotor (33) as seen from the axial direction. The mechanism-side fitting section (41d) includes a facing section (81) and a circumferential edge protruding section (82). The motor-side fitting section (31d) includes fitting end surfaces (71f, 71g) that are in contact with the facing section (81) in the axial direction, and a fitting-side surface (71a) that is in contact with the circumferential edge protruding section (82). The fitting end surfaces (71f, 71g) include a plurality of end surfaces (71f, 71g) provided in a non-continuous manner in the circumferential direction.

Description

Vehicle steering device

[0001] The present disclosure relates to a vehicle steering system.

[0002] For example, as disclosed in Patent Document 1, there is a vehicle steering device configured to apply an assist force to a column shaft by the torque of a motor. The motor is connected to the column shaft via a reduction mechanism. The reduction mechanism is a transmission mechanism fastened to the motor to transmit the torque of the motor to the column shaft. The motor has a motor housing that accommodates a stator and a rotor. The motor housing is fastened to a mechanism housing of the transmission mechanism via a plate. The plate is fixed to a radially inner portion of the motor housing at the bottom of the motor housing from which the motor output shaft protrudes. The radially inner portion of the motor housing is less affected by the radial expansion and contraction of the motor housing due to the attractive and repulsive forces acting between the stator and rotor when the motor is driven. This makes it difficult for vibrations generated by the radial expansion and contraction of the motor housing to be transmitted to the plate. In other words, vibrations generated by the radial expansion and contraction of the motor housing are suppressed from being transmitted to the transmission mechanism.

[0003] JP 2012-90496 A

[0004] In the above-mentioned Patent Document 1, the radially inner portion of the motor housing to which the plate is fixed is located near the output shaft and overlaps with the rotor when viewed along the axis of the motor's output shaft. This means that the portion of the motor housing to which the plate is fixed has lower axial rigidity than other portions of the motor, making it more susceptible to vibration, for example, when the vehicle is running. This reduces the durability of the motor housing, and therefore the motor.

[0005] A vehicle steering device according to one aspect of the present disclosure has an operation mechanism to which an operation member of a vehicle, which is operated to steer the steered wheels of the vehicle, is coupled. The vehicle steering device includes a motor configured to generate torque for varying the operation force required to operate the operation member, and a transmission mechanism configured to transmit the torque generated by the motor to the operation mechanism. The motor has a motor housing that accommodates a stator and a rotor. An output shaft that rotates integrally with the rotor has an output portion that protrudes outward from the motor housing. The transmission mechanism has a mechanism housing that accommodates a portion of the operation mechanism and the output portion so as to connect the portion of the operation mechanism to the output shaft. The motor housing has a motor-side fitting portion that fits into the mechanism housing in an axial direction along the axis of the output shaft. The mechanism housing has a mechanism-side fitting portion that fits into the motor-side fitting portion in the axial direction. The mechanism-side fitting portion and the motor-side fitting portion are arranged radially outward of the rotor when viewed in the axial direction. The mechanism-side fitting portion has a facing portion that faces the motor-side fitting portion in the axial direction and a peripheral protrusion that extends in the axial direction from the periphery of the facing portion. The motor-side fitting portion has a fitting end face that abuts against the facing portion in the axial direction and a fitting side face that is disposed inside the peripheral protrusion in the radial direction of the output shaft and abuts against the peripheral protrusion. The fitting end face has a plurality of end faces that are discontinuously provided along the circumferential direction of the output shaft.

[0006] 1 is a diagram showing a schematic configuration of a vehicle steering device according to an embodiment; FIG. 2 is a diagram showing a schematic configuration of a motor and a transmission mechanism of FIG. 1; FIG. 3 is a cross-sectional view showing the configuration of the motor and the transmission mechanism of FIG. 1; FIG. 4 is a perspective view showing the configuration of a motor housing of FIG. 3; FIG. 5 is a plan view showing the configuration of the motor housing of FIG. 3; FIG. 6 is a perspective view showing the configuration of a worm housing of FIG. 3; FIG. 7 is a schematic view of the structure of a bolt fastening portion of FIG. 3, i.e., a portion including a bolt fastening surface; FIG. 8 is a schematic view of the structure of a portion including a normal end face of FIG. 3; FIG. 9 is a schematic view of the structure of a portion including an end face of a connecting portion of FIG. 3;

[0007] A vehicle steering device according to one embodiment will be described with reference to the drawings. As shown in FIG. 1 , an electric power steering device 10 is an example of a vehicle steering device mounted on a vehicle. The electric power steering device 10 includes an operation mechanism 13 and a steering shaft 14. The operation mechanism 13 and the steering shaft 14 form a power transmission path between an operation member 11 of the vehicle and steered wheels 12, 12 of the vehicle. The operation member 11 is, for example, a steering wheel. The operation mechanism 13 includes a column shaft 15, an intermediate shaft 16, and a pinion shaft 17, which are connected to each other. The column shaft 15 is rotatably supported inside a steering column 13a fixed to the vehicle body. The column shaft 15 connects the operation member 11 to the intermediate shaft 16. The intermediate shaft 16 connects the column shaft 15 to the pinion shaft 17. The steering shaft 14 extends in the left-right direction in FIG. 1 , which is the width direction of the vehicle body. The steering shaft 14 is housed inside a housing 18 fixed to the vehicle body. The steered wheels 12, 12 are connected to both ends of the steered shaft 14 via tie rods 19, 19, respectively.

[0008] The pinion teeth 17a of the pinion shaft 17 are engaged with the rack teeth 14a of the steered shaft 14. As a result, the steered shaft 14 moves along its axis in conjunction with the rotation of the operating member 11, thereby changing the steered angle of the steered wheels 12, 12.

[0009] <Regarding the Operation Mechanism> As shown in Figures 1 and 2, the operation mechanism 13 has an assist mechanism 20. The assist mechanism 20 is configured to apply an assist force to the steering shaft 14. The assist force is a driving force applied to the operation member 11 to change the operating force required to operate the operation member 11. The assist mechanism 20 has a motor 30 and a transmission mechanism 40. The motor 30 is fixed to the outside of the transmission mechanism 40.

[0010] The steering column 13a is fixed to the vehicle body B via a fixing member BR1 such as a bracket. The transmission mechanism 40 is fixed to the vehicle body B via a fixing member BR2 such as a bracket. In other words, the motor 30 is fixed to the vehicle body B via the steering column 13a and the transmission mechanism 40.

[0011] <Regarding the Motor> As shown in Fig. 3, the motor 30 is a source of assist force. The motor 30 is, for example, a three-phase brushless motor. The motor 30 has a motor housing 31, a stator 32, a rotor 33, an output shaft 34, and a control device 50. The motor housing 31 accommodates the stator 32 and the rotor 33. An output portion 34a, which is a first end of the output shaft 34 that rotates integrally with the rotor 33, protrudes outside the motor housing 31.

[0012] The control device 50 is provided integrally with the motor 30. The control device 50 acquires detection results from various sensors mounted on the vehicle as information indicating the driver's request or driving state, and controls the motor 30 in accordance with the acquired information. The sensors include, for example, a torque sensor, a vehicle speed sensor, and a rotation angle sensor. The torque sensor is provided midway along the column shaft 15. The torque sensor detects the operating torque applied to the column shaft 15. The vehicle speed sensor detects the vehicle speed. The rotation angle sensor is provided in the motor 30. The rotation angle sensor detects the rotation angle of the output shaft 34. The control device 50 performs assist control by controlling the power supply to the motor 30, which generates an assist force according to the operating torque and vehicle speed. The control device 50 performs vector control of the motor 30 using the rotation angle of the output shaft 34 detected by the rotation angle sensor.

[0013] <Transmission Mechanism> As shown in Fig. 3, the transmission mechanism 40 reduces the rotation of the motor 30 and transmits it to the column shaft 15. The transmission mechanism 40 is, for example, a worm reduction mechanism. More specifically, the transmission mechanism 40 has a worm housing 41, a worm shaft 42, and a worm wheel 43. The worm housing 41 accommodates a portion of the column shaft 15 and also accommodates the worm shaft 42 and the worm wheel 43. In this embodiment, the worm housing 41 is an example of a mechanism housing.

[0014] A joint 42a, which is a first end of the worm shaft 42, is connected to the output shaft 34, i.e., the motor 30, via the output portion 34a. The worm shaft 42 has a worm portion 42c between the joint 42a and a shaft end 42b, which is a second end opposite the joint 42a. The worm wheel 43 is meshed with the worm shaft 42 via the worm portion 42c. The worm wheel 43 has a through hole 43a that passes through its axis. The column shaft 15 is inserted through the through hole 43a and connected to the worm wheel 43 so as to be rotatable together with it. The first end 15a of the column shaft 15 is connected to the operating member 11. The column shaft 15 is connected to the worm wheel 43, i.e., the transmission mechanism 40, between the first end 15a and a second end 15b opposite the first end 15a. In other words, the transmission mechanism 40 connects the column shaft 15 and the output shaft 34 via the worm shaft 42 and the worm wheel 43 .

[0015] <Regarding the Arrangement of the Motor and Transmission Mechanism> In FIGS. 1 to 3 , a horizontal line X extending horizontally is shown, and the direction of gravity is indicated by an arrow Y. The axis Z1 of the column shaft 15 forms an angle θ1 with the horizontal line X. The angle θ1 is, for example, an acute angle. That is, the axis Z1 intersects with the horizontal line X so that the first end 15 a is disposed above the direction of gravity and the second end 15 b is disposed below the direction of gravity. The axis of the worm wheel 43 coincides with the axis Z1. In this case, the axis Z2 of the worm shaft 42 forms an angle θ2 with the axis Z1. The angle θ2 is, for example, a right angle. That is, the axis Z2 intersects with the horizontal line X and the axis Z1 so that the joint 42 a is disposed above the direction of gravity and the shaft end 42 b is disposed below the direction of gravity. The axis Z2 passes through the center of gravity G of the worm wheel 43 and forms an angle θ3 with a center of gravity line Z1a that is perpendicular to the axis Z1. The angle θ3 is, for example, an acute angle. In other words, the position of the transmission mechanism 40 in the circumferential direction of the axis Z1 is adjusted so that the axis Z2 forms the angle θ3 with the center of gravity line Z1a.

[0016] As a result, the motor 30 is disposed in a position where the axis Z2 of the output shaft 34 intersects with the horizontal line X and the output portion 34a protrudes from the lower side in the direction of gravity of the motor housing 31. The transmission mechanism 40 is also disposed in a position where it accommodates the output portion 34a from the lower side of the motor 30 in the direction of gravity.

[0017] <Configuration of the Motor and Transmission Mechanism> As shown in Figure 3, the motor housing 31 is cylindrical with an open first end 31a on the upper side in the direction of gravity. The motor housing 31 is made of a metal such as aluminum. The motor housing 31 has a main body 31c and a motor-side fitting 31d. The main body 31c is, for example, cylindrical. The motor-side fitting 31d is provided at a second end 31b of the main body 31c and forms the bottom of the motor housing 31.

[0018] A stator 32 is fixed to the inner periphery of the main body 31c. The stator 32 has a stator core 32a and coils 32b. The stator core 32a is, for example, cylindrical. The stator core 32a has a plurality of teeth 32c protruding from its inner periphery. The coils 32b are wound around each of the plurality of teeth 32c.

[0019] The rotor 33 is disposed on the inner circumferential side of the stator 32 with a radial gap therebetween. The rotor 33 includes a rotor core 33a and magnets 33b. The rotor core 33a is cylindrical. The rotor core 33a is fixed to the outer periphery of the output shaft 34 so as to be rotatable integrally with the output shaft 34. The output shaft 34 is rotatably supported relative to the motor housing 31 via bearings 34b and 34c. The magnets 33b are arranged, for example, side by side in the circumferential direction of the rotor core 33a. The magnets 33b are arranged so that their magnetic poles alternate between north and south poles in the circumferential direction of the rotor core 33a.

[0020] The bearing 34b is fixed to a lid portion 60 attached to the first end 31a of the main body portion 31c. The lid portion 60 is disk-shaped. The lid portion 60 is made of a metal such as aluminum. The first end 31a of the main body portion 31c and the lid portion 60 are spigot-fitted together. The first end 31a of the main body portion 31c and the lid portion 60 are fastened to each other with bolts or the like outside the motor housing 31. As a result, the opening of the first end 31a of the main body portion 31c is closed by the lid portion 60. The lid portion 60 supports a second end of the output shaft 34 opposite the output portion 34a at the radial center.

[0021] The bearing 34c is fixed to a motor-side fitting portion 31d of the main body portion 31c. The motor-side fitting portion 31d has a shaft hole 31e in its radial center. The motor-side fitting portion 31d supports a portion of the output shaft 34 near the first end at its radial center. The output portion 34a protrudes outside the motor housing 31 through the shaft hole 31e of the motor-side fitting portion 31d.

[0022] The control device 50 is provided on the opposite side of the main body 31c with respect to the lid 60. The control device 50 has a substrate 50a and a plurality of electronic components 50b. The substrate 50a is fixed to the lid 60 so that a first surface in the plate thickness direction faces the lid 60. The plurality of electronic components 50b are mounted on both sides of the substrate 50a. The plurality of electronic components 50b include a rotation angle sensor. The rotation angle sensor is arranged, for example, on the first surface of the substrate 50a so as to face the second end of the output shaft 34 in the axial direction. The control device 50 is covered by a cover 61 from the opposite side of the lid 60. The cover 61 is made of a metal such as aluminum.

[0023] As shown in FIG. 3 , the worm housing 41 has a shape in which two tubes, one opening upward in the direction of gravity along the axis Z1 and the other opening upward in the direction of gravity along the axis Z2, are connected to each other. The upper side of the axis Z1 in the direction of gravity is the front side of the paper in FIG. 3 along the axis Z1. In other words, the lower side of the axis Z1 in the direction of gravity is the rear side of the paper in FIG. 3 along the axis Z1. The upper side of the axis Z2 in the direction of gravity is the upper side in FIG. 3 along the axis Z2. In other words, the lower side of the axis Z2 in the direction of gravity is the lower side in FIG. 3 along the axis Z2. The worm housing 41 is made of a metal such as aluminum. The worm housing 41 has a first main body portion 41a and a second main body portion 41b. The first main body portion 41a is, for example, cylindrical, having an axial length along the axis Z1 and a diameter greater than the axial length. The diameter of the first main body portion 41a is greater than the diameter of the worm wheel 43. The first body portion 41a accommodates the worm wheel 43, i.e., a portion of the column shaft 15. The second body portion 41b is, for example, cylindrical with an axial length along the axis Z2 and a diameter smaller than the axial length. The axial length of the second body portion 41b is greater than the axial length of the worm shaft 42. The second body portion 41b accommodates the worm shaft 42, i.e., the output portion 34a. The interiors of the first body portion 41a and the second body portion 41b are connected to each other via a connecting portion 41c. The worm shaft 42 and the worm wheel 43 are meshed with each other via the connecting portion 41c.

[0024] A fixing member BR2 is provided on the lower side of the first main body portion 41a in the direction of gravity. A main body cover 62 is provided on the upper side of the first main body portion 41a in the direction of gravity. The main body cover 62 houses the portion of the column shaft 15 where the torque sensor is provided. The main body cover 62 closes the opening on the upper side of the first main body portion 41a in the direction of gravity. The main body cover 62 has a shaft hole 62a in the radial center. The column shaft 15 enters the inside of the worm housing 41 through the shaft hole 62a of the main body cover 62.

[0025] A main body lid 63 is provided on the lower side of the second main body 41b in the direction of gravity. The main body lid 63 closes the opening of the second main body 41b on the lower side in the direction of gravity. A mechanism-side fitting portion 41d is provided on the upper side of the second main body 41b in the direction of gravity, i.e., on the opposite side of the main body lid 63. The mechanism-side fitting portion 41d is spigot-fitted with the motor-side fitting portion 31d when connecting the motor 30 and the transmission mechanism 40. The motor-side fitting portion 31d and the mechanism-side fitting portion 41d are fastened together by a plurality of bolts 64 from the lower side in the direction of gravity of the axis Z2 while they are fitted together. For example, two bolt fastening portions 65 are formed by fastening using the bolts 64. The mechanism-side fitting portion 41d includes a portion that is connected to the first main body 41a.

[0026] The worm shaft 42 is rotatably supported by the second main body portion 41 b via bearings 42 d and 42 e. The worm shaft 42 is inserted into the second main body portion 41 b from above in the direction of gravity so that the shaft end 42 b is adjacent to the main body lid 63.

[0027] The bearing 42d is fixed to the second main body portion 41b near the main body lid 63. The bearing 42e is fixed to the mechanism-side fitting portion 41d of the second main body portion 41b. The mechanism-side fitting portion 41d has an axial hole 41e in its radial center. The mechanism-side fitting portion 41d supports a portion of the worm shaft 42 near the joint 42a in its radial center. The joint 42a protrudes outside the worm housing 41 through the axial hole 41e of the mechanism-side fitting portion 41d.

[0028] 4 and 5, the motor-side fitting portion 31d of the motor housing 31 is located at the second end 31b of the main body portion 31c. The axial direction of the motor-side fitting portion 31d coincides with the direction along the axis Z2. In other words, the radial direction of the motor-side fitting portion 31d coincides with the direction perpendicular to the axis Z2. The motor-side fitting portion 31d has a fitting protrusion 71, an extension 72, and a groove 73.

[0029] The fitting protrusion 71 extends in the axial direction from the second end 31b of the main body portion 31c. The fitting protrusion 71 extends continuously along the circumferential direction of the main body portion 31c. The fitting protrusion 71 is located radially inward from the outer circumferential edge of the main body portion 31c. In the case of the motor 30 shown in FIG. 3, the fitting protrusion 71 is located radially outward from the rotor 33 when viewed from the axial direction. The fitting protrusion 71 is located so as to overlap with the stator 32 when viewed from the axial direction. The outer circumferential surface 71a of the fitting protrusion 71 is a cylindrical surface that is perpendicular to the radial direction and extends parallel to the axial direction.

[0030] The mating protrusion 71 has two motor-side bolt fastening portions 71b and two mating legs 71c. The motor-side bolt fastening portions 71b and the mating legs 71c are portions of the mating protrusion 71 that protrude more axially than the other portions. The motor-side bolt fastening portions 71b and the mating legs 71c are alternately arranged at equal intervals in the circumferential direction. That is, the two motor-side bolt fastening portions 71b and the two mating legs 71c are arranged at equal angular offsets of 90 degrees from each other in the circumferential direction. The two motor-side bolt fastening portions 71b are arranged at equal angular offsets of 180 degrees from each other in the circumferential direction. The two mating legs 71c are arranged at equal angular offsets of 180 degrees from each other in the circumferential direction. The mating protrusion 71 has four connecting portions 71d extending between adjacent motor-side bolt fastening portions 71b and mating legs 71c in the circumferential direction. The connecting portion 71d is a portion that protrudes less in the axial direction than the motor-side bolt fastening portion 71b and the fitting leg portion 71c. The motor-side bolt fastening portion 71b and the fitting leg portion 71c are discontinuously provided along the outer peripheral surface 71a.

[0031] The motor-side bolt fastening portion 71b is cylindrical. In the radial direction of the fitting convex portion 71, the outermost position of the motor-side bolt fastening portion 71b coincides with the outer peripheral surface 71a of the fitting convex portion 71. In the radial direction of the fitting convex portion 71, the innermost position of the motor-side bolt fastening portion 71b is located inside the inner peripheral surface of other portions of the fitting convex portion 71. A bolt fastening hole 71e is provided at the center of the motor-side bolt fastening portion 71b when viewed from the axial direction. The bolt fastening hole 71e, for example, penetrates the motor-side bolt fastening portion 71b in the axial direction and reaches the main body portion 31c. The motor-side bolt fastening portion 71b has a bolt fastening surface 71f around the bolt fastening hole 71e. The diameter of the bolt fastening surface 71f is larger than the diameter of the bolt fastening hole 71e. In this embodiment, the bolt fastening surface 71f is an example of a fitting end surface. The outer peripheral surface 71a of the fitting protrusion 71 is an example of a fitting side surface.

[0032] The fitting leg portion 71c is a columnar body having a crescent-shaped cross section perpendicular to the axial direction. The outermost position of the fitting leg portion 71c in the radial direction of the fitting protrusion 71 coincides with the outer peripheral surface 71a of the fitting protrusion 71. The innermost position of the fitting leg portion 71c in the radial direction of the fitting protrusion 71 is outer than the innermost position of the motor-side bolt fastening portion 71b. The fitting leg portion 71c has a crescent-shaped normal end surface 71g. When viewed from the axial direction, the diameter of a circle tangent to the innermost radial portions of the normal end surfaces 71g of the two fitting legs 71c is larger than the diameter of a circle tangent to the innermost radial portions of the two bolt fastening surfaces 71f. In this embodiment, the normal end surface 71g is an example of a fitting end surface.

[0033] The connecting portion 71d extends in an arc shape to connect the motor-side bolt fastening portion 71b and the fitting leg portion 71c that are adjacent to each other in the circumferential direction. In the radial direction of the fitting protrusion 71, the outermost position of the connecting portion 71d coincides with the outer peripheral surface 71a of the fitting protrusion 71. In the radial direction of the fitting protrusion 71, the innermost position of the connecting portion 71d coincides with the innermost position of the fitting leg portion 71c. The radial thickness of the connecting portion 71d is constant. The radial thickness of the fitting protrusion 71 is constant in areas other than where the motor-side bolt fastening portion 71b is provided. The connecting portion 71d has an arc-shaped end face 71h. When viewed from the axial direction, the diameter of a circle tangent to the radially innermost portion of the four end faces 71h coincides with the diameter of a circle tangent to the radially innermost portion of the end face 71g.

[0034] The extension 72 extends in the axial direction from the outer peripheral edge of the second end 31b of the main body 31c. The inner peripheral surface 72a of the extension 72 is an inclined surface inclined with respect to the axial direction. The extension 72 has a radial thickness that decreases toward the tip 72b. The extension 72 is located radially outward of the mating protrusion 71.

[0035] The groove 73 is provided between the fitting convex portion 71 and the extending portion 72 in the radial direction of the main body portion 31c. The inner wall surface 73a of the groove 73 is composed of the outer peripheral surface 71a of the fitting convex portion 71 and the inner peripheral surface 72a of the extending portion 72. The bottom surface 73b of the groove 73 is a surface that connects the outer peripheral surface 71a of the fitting convex portion 71 and the inner peripheral surface 72a of the extending portion 72. The groove 73 has a depth in the axial direction. The depth of the groove 73 corresponds to the length of the extending portion 72 extending along the axial direction of the main body portion 31c. The radial width of the groove 73 increases the farther from the bottom surface 73b.

[0036] <Configuration of the Mechanism-Side Fitting Portion> As shown in Figure 6, the mechanism-side fitting portion 41d of the worm housing 41 is a portion of the second main body portion 41b on the opposite side from the main body lid 63. The axial direction of the mechanism-side fitting portion 41d coincides with the direction along the axis Z2. The radial direction of the mechanism-side fitting portion 41d coincides with the direction perpendicular to the axis Z2. The mechanism-side fitting portion 41d has an opposing portion 81 and a peripheral protrusion 82.

[0037] The facing portion 81 is ring-shaped when viewed in the axial direction. The facing portion 81 extends radially outward from the periphery of the axial hole 41e of the mechanism-side fitting portion 41d. The facing portion 81 extends radially outward from the outer periphery of the end of the second main body portion 41b. When viewed in the axial direction, the facing portion 81 extends to the radially outer side of the rotor 33 in relation to the motor 30. When viewed in the axial direction, the facing portion 81 overlaps with the stator 32 in relation to the motor 30. The facing portion 81 has a facing surface 81a that is perpendicular to the axial direction. Two bolt fastening holes 81b are provided in the facing portion 81. The bolt fastening holes 81b, for example, penetrate the facing portion 81 in the axial direction. The two bolt fastening holes 81b are arranged circumferentially offset from each other by an equal angle of 180 degrees.

[0038] The peripheral protrusion 82 extends in the axial direction from the outer circumferential edge of the opposing portion 81. The peripheral protrusion 82 extends continuously along the circumferential direction of the opposing portion 81. In relation to the motor 30, the peripheral protrusion 82 is disposed radially outward of the rotor 33 when viewed from the axial direction. In relation to the motor 30, the peripheral protrusion 82 is disposed so as to include a portion that overlaps with the stator 32 when viewed from the axial direction. The inner circumferential surface 82a of the peripheral protrusion 82 is a cylindrical surface that is perpendicular to the radial direction and extends parallel to the axial direction.

[0039] As shown in Figures 6 to 9, the peripheral protrusion 82 has a groove insert portion 82c. The groove insert portion 82c has a tip 82b, a gradually changing portion 82d, and a thin-walled portion 82e. The tip 82b of the groove insert portion 82c is also the tip of the peripheral protrusion 82. The gradually changing portion 82d is a portion between the base 82f and the tip 82b of the peripheral protrusion 82, and has a radial thickness that gradually decreases toward the tip 82b. The thin-walled portion 82e is a portion between the gradually changing portion 82d and the tip 82b of the peripheral protrusion 82, and has a constant radial thickness toward the tip 82b. The radial thickness of the thin-walled portion 82e is the smallest of all portions of the peripheral protrusion 82. The portion of the peripheral protrusion 82 other than the groove insert portion 82c has an outer peripheral surface 82g that is perpendicular to the radial direction. The outer peripheral surface 82g is a cylindrical surface that extends parallel to the axial direction.

[0040] 7 to 9, the axial length Lw from the base 82f to the tip 82b of the peripheral protrusion 82 is smaller than the axial length Lm from the bolt fastening surface 71f or the normal end face 71g to the bottom surface 73b of the groove 73 in relation to the motor-side fitting portion 31d. The outer peripheral surface 82g of the peripheral protrusion 82 overlaps with the tip 72b of the extension portion 72 when viewed from the axial direction. The diameter Rw of the inner peripheral surface 82a of the peripheral protrusion 82 is equal to or smaller than the diameter Rm of the outer peripheral surface 71a of the fitting convex portion 71 in relation to the motor-side fitting portion 31d. The radial thickness Tw of the thin-walled portion 82e of the groove insertion portion 82c is smaller than the minimum radial width Tm of the groove 73 in relation to the motor-side fitting portion 31d.

[0041] <Regarding the Fitting Between the Motor-Side Fitting Portion and the Mechanism-Side Fitting Portion> As shown in Figures 3 and 7 to 9, the motor-side fitting portion 31d and the mechanism-side fitting portion 41d are fitted together by fitting the fitting protrusion 71 into the peripheral protrusion 82. The outer peripheral surface 71a of the fitting protrusion 71 and the inner peripheral surface 82a of the peripheral protrusion 82 abut against each other in the radial direction. This allows the fitting protrusion 71 to be positioned in the radial direction when it is fitted into the peripheral protrusion 82. The fitting protrusion 71 abuts against the opposing portion 81 in the axial direction. This allows the fitting protrusion 71 to be positioned in the axial direction when it is fitted into the peripheral protrusion 82. This fitting portion is positioned radially outward of the rotor 33 and includes a portion that overlaps with the stator 32 when viewed from the axial direction. In this embodiment, the outer peripheral surface 71a of the fitting protrusion 71 and the inner peripheral surface 82a of the peripheral protrusion 82 are examples of abutting surfaces that abut against each other.

[0042] 7 shows a schematic diagram of the end face structure of the portion including the motor-side bolt fastening portion 71b in the spigot-fitted state. In this case, the outer peripheral surface 71a of the fitting protrusion 71 abuts against the entire inner peripheral surface 82a of the peripheral protrusion 82 in the radial direction. The bolt fastening surface 71f abuts against the opposing surface 81a in the axial direction.

[0043] The circumferential positions of the motor-side fitting portion 31d and the mechanism-side fitting portion 41d are adjusted so that the bolt fastening holes 71e, 81b are in communication with each other in the axial direction. A bolt 64 is inserted from the mechanism-side fitting portion 41d toward the motor-side fitting portion 31d through the bolt fastening holes 71e, 81b, which are in communication with each other in the axial direction. This fastens the motor-side fitting portion 31d and the mechanism-side fitting portion 41d together. The combination of the motor-side bolt fastening portion 71b, including the bolt fastening hole 71e, and the bolt fastening hole 81b constitutes one bolt fastening portion 65. The two bolt fastening portions 65 are located radially inward of the portion where the fitting protrusion 71 is spigot-fitted with the peripheral protrusion 82.

[0044] 8 shows a schematic diagram of the end face structure of the portion including the fitting leg portion 71c in the spigot-fitted state. In this case, the outer peripheral surface 71a of the fitting protrusion 71 abuts against the entire inner peripheral surface 82a of the peripheral protrusion 82 in the radial direction. Furthermore, the normal end surface 71g abuts against the opposing surface 81a in the axial direction. The area where the normal end surface 71g abuts against the opposing surface 81a in the radial direction of the fitting protrusion 71 is smaller than the area where the bolt fastening surface 71f abuts against the opposing surface 81a. This is because the innermost position of the fitting leg portion 71c is located outside the innermost position of the motor-side bolt fastening portion 71b in the radial direction of the fitting protrusion 71.

[0045] 9 is a schematic diagram illustrating the end surface structure of a portion including the spigot-fitted connecting portion 71d. At the connecting portion 71d, the outer peripheral surface 71a of the mating protrusion 71 radially contacts a portion of the inner peripheral surface 82a of the peripheral protrusion 82. That is, the end surface 71h of the connecting portion 71d faces the opposing surface 81a in the axial direction but does not contact the opposing surface 81a in the axial direction. The radial area of ​​the mating protrusion 71 where the outer peripheral surface 71a contacts the inner peripheral surface 82a is smaller than the area where the outer peripheral surfaces 71a of the motor-side bolt fastening portion 71b and the mating leg portion 71c contact the inner peripheral surface 82a. This is because the connecting portion 71d protrudes less axially than the motor-side bolt fastening portion 71b and the mating leg portion 71c. That is, the portion of the inner peripheral surface 82a corresponding to the connecting portion 71d has a portion in the axial direction that does not fit with the connecting portion 71d. For example, the protrusion amount of the connecting portion 71d may be large enough to determine the radial position when the fitting convex portion 71 is spigot-fitted with the peripheral protrusion 82.

[0046] 7 to 9, a portion of the thin-walled portion 82e, including the tip 82b, of the groove insertion portion 82c of the peripheral protrusion 82 is inserted into the groove 73. In this case, when inserted into the groove 73, the tip 82b faces the bottom surface 73b of the groove 73 with an axial gap Adg. The gap Adg is equal to the difference between the axial length Lw from the base 82f of the peripheral protrusion 82 to the tip 82b and the axial length Lm from the bolt fastening surface 71f or the normal end face 71g to the bottom surface 73b of the groove 73. The gap Adg is smaller than the axial length Ln from the bottom surface 73b of the groove 73 to the tip 72b of the extension portion 72. In other words, the extension portion 72 extends downward in the direction of gravity so that the axial position of the extension portion 72 overlaps with a portion of the thin-walled portion 82e, i.e., the peripheral protrusion 82.

[0047] Furthermore, when inserted into the groove 73, the thin-walled portion 82e faces the inner wall surface 73a of the groove 73, i.e., the outer peripheral surface 71a of the fitting convex portion 71 and the inner peripheral surface 72a of the extending portion 72, with a radial gap Rdg between them. The gap Rdg is the sum of the radial gap between the thin-walled portion 82e and the outer peripheral surface 71a and the radial gap between the thin-walled portion 82e and the inner peripheral surface 72a. The gap Rdg is larger than the difference (gap Rdg1 + gap Rdg2) between the radial thickness Tw of the thin-walled portion 82e of the groove insertion portion 82c and the minimum radial width Tm of the groove 73.

[0048] 3, the motor-side fitting portion 31d and the mechanism-side fitting portion 41d are fitted to each other at a position radially outside the rotor 33 and overlapping with the stator 32, as viewed from the axial direction. This ensures axial rigidity of the motor 30 at the portion where the fitting convex portion 71 is spigot-fitted with the peripheral protrusion 82.

[0049] 9, the axial engagement range between the motor-side fitting portion 31d and the mechanism-side fitting portion 41d is smaller where the bolt fastening surface 71f and normal end surface 71g are not present, i.e., where the connecting portion 71d is present, than where other locations are. This reduces the rigidity of the engagement between the motor-side fitting portion 31d and the mechanism-side fitting portion 41d where the connecting portion 71d is present. Therefore, vibrations generated by the radial expansion and contraction of the motor housing 31 are less likely to be transmitted to the mechanism-side fitting portion 41d, i.e., the transmission mechanism 40. This reduces the deterioration of the durability of the motor housing 31, i.e., the motor 30.

[0050] <Effects of this embodiment> (1-1) When vibrations generated by the radial expansion and contraction of the motor housing 31 are less likely to be transmitted to the mechanism side fitting portion 41d, i.e., the transmission mechanism 40, the deterioration of the durability of the motor housing 31, i.e., the motor 30, can be suppressed.

[0051] (1-2) As shown in Figures 7 and 8, the bolt fastening surface 71f and the normal end surface 71g each abut against the opposing surface 81a in the axial direction. The bolt fastening surface 71f also serves as the bolt fastening portion 65. This is effective in reducing the radial dimensions of the motor 30 and the transmission mechanism 40.

[0052] (1-3) As shown in Figures 7 and 8, the innermost position of the fitting leg portion 71c in the radial direction of the fitting protrusion 71 is outside the innermost position of the motor-side bolt fastening portion 71b. Therefore, the area where the normal end face 71g abuts against the opposing surface 81a in the radial direction of the fitting protrusion 71 is smaller than the area where the bolt fastening surface 71f abuts against the opposing surface 81a. This reduces the rigidity of the fit between the motor-side fitting portion 31d and the mechanism-side fitting portion 41d compared to when the area where the normal end face 71g abuts against the opposing surface 81a is the same as the area where the bolt fastening surface 71f abuts against the opposing surface 81a. As a result, vibrations generated by the radial expansion and contraction of the motor housing 31 are less likely to be transmitted by the mechanism-side fitting portion 41d, i.e., the transmission mechanism 40.

[0053] (1-4) As shown in Figure 5, the motor-side bolt fastening portions 71b and the fitting legs 71c are alternately arranged at equal intervals in the circumferential direction. This makes it possible to suppress unevenness in the rigidity of the fitting between the motor-side fitting portion 31d and the mechanism-side fitting portion 41d at the location where the fitting protrusion 71 is spigot-fitted to the peripheral protrusion 82.

[0054] (1-5) As shown in Figure 5, the two motor-side bolt fastening portions 71b and the two fitting legs 71c are arranged at equal 90-degree offsets along the circumferential direction. This makes it possible to more effectively suppress unevenness in rigidity related to the fitting between the motor-side fitting portion 31d and the mechanism-side fitting portion 41d at the location where the fitting convex portion 71 is fitted to the peripheral protrusion 82.

[0055] (1-6) As shown in Figures 3 and 7 to 9, the extension portion 72 is located above the peripheral protrusion 82 in the direction of gravity and radially outward of the outer peripheral surface 82g of the peripheral protrusion 82. The peripheral protrusion 82 is the radially outermost portion of the mechanism-side fitting portion 41d. The extension portion 72 extends downward in the direction of gravity so as to overlap with a portion of the thin-walled portion 82e, i.e., the peripheral protrusion 82, in the axial direction. In other words, the extension portion 72 covers the peripheral protrusion 82, i.e., the mechanism-side fitting portion 41d, from above in the direction of gravity. The portion of the fitting protrusion 71 that is spigot-fitted with the peripheral protrusion 82 is the radially inner portion of the extension portion 72. This allows the extension portion 72 to externally cover the portion of the fitting protrusion 71 that is spigot-fitted with the peripheral protrusion 82. This makes it possible to prevent water from entering the inside of the transmission mechanism 40 through a gap at the portion where the fitting convex portion 71 is spigot-fitted to the peripheral protrusion 82. No additional components such as an O-ring are required at the portion where the fitting convex portion 71 is spigot-fitted to the peripheral protrusion 82.

[0056] (1-7) As shown in Figure 7, the two bolt fastening portions 65 are located radially inward of the portion where the fitting protrusion 71 is spigot-fitted to the peripheral protrusion 82. This allows the radial dimensions of the motor 30 and the transmission mechanism 40 to be reduced.

[0057] (1-8) As shown in Figures 7 to 9, when the tip 82b is inserted into the groove 73, it faces the bottom surface 73b of the groove 73 with an axial gap Adg. The gap Adg can absorb assembly tolerances in the axial direction when assembling the motor 30 and the transmission mechanism 40. This is effective in improving ease of assembly.

[0058] (1-9) As shown in Figures 7 to 9, when inserted into the groove 73, the thin-walled portion 82e faces the inner wall surface 73a of the groove 73, i.e., the outer peripheral surface 71a of the fitting protrusion 71 and the inner peripheral surface 72a of the extension portion 72, with a radial gap Rdg. The gap Rdg can absorb assembly tolerances in the axial direction when assembling the motor 30 and the transmission mechanism 40. This is effective in improving ease of assembly.

[0059] (1-10) The gaps Adg and Rdg can suppress the occurrence of capillary action, etc., even if water flows around from the outside of the extension portion 72. This makes it possible to more effectively suppress the intrusion of water into the transmission mechanism 40.

[0060] Other Embodiments The above embodiment may be modified as follows: The following other embodiments may be combined with each other within the scope of no technical contradiction.

[0061] The gap Adg may be larger or smaller than the embodiment, and can be changed as appropriate. In this case, the gap Adg is preferably equal to or greater than the length Ln. The gap Rdg may be larger or smaller than the embodiment, and can be changed as appropriate.

[0062] The gap Adg does not have to be present. The same applies to the gap Rdg. For example, if there are no gaps Adg and Rdg, the thin-walled portion 82e abuts against the inner wall surface 73a and the bottom surface 73b when inserted into the groove 73. In this case, a labyrinth structure may be formed between the abutting surfaces by adjusting the surface roughness of the abutting surfaces of the thin-walled portion 82e, the inner wall surface 73a, and the bottom surface 73b.

[0063] The multiple bolt fastening portions 65 may be disposed radially outward from the portion where the fitting protrusion 71 is spigot-fitted to the peripheral protrusion 82. The outer peripheral surface 82g of the peripheral protrusion 82 may coincide with the outer peripheral surface of the extension portion 72 when viewed in the axial direction. Furthermore, if the portion where the fitting protrusion 71 is spigot-fitted to the peripheral protrusion 82 can be covered from the outside, the outer peripheral surface 82g of the peripheral protrusion 82 may be located radially outward from the outer peripheral surface of the extension portion 72.

[0064] The motor-side bolt fastening portions 71b and the fitting legs 71c may be arranged so as to be offset from each other by different angles along the circumferential direction. That is, the two motor-side bolt fastening portions 71b may be arranged so as to be offset from each other by an angle other than 180 degrees along the circumferential direction. Furthermore, the phases of the two fitting legs 71c may be arranged so as to be offset from each other by an angle other than 180 degrees along the circumferential direction.

[0065] The two motor-side bolt fastening portions 71b may be arranged adjacent to each other in the circumferential direction. The two fitting leg portions 71c may be arranged adjacent to each other in the circumferential direction. The innermost position of the fitting leg portion 71c in the radial direction of the fitting protrusion 71 may be inside or coincide with the innermost position of the motor-side bolt fastening portion 71b. For example, if the innermost position of the fitting leg portion 71c in the radial direction of the fitting protrusion 71 coincides with the innermost position of the motor-side bolt fastening portion 71b, the bolt fastening surface 71f and the normal end surface 71g may have the same shape. In this case, the shapes of the bolt fastening surface 71f and the normal end surface 71g may both be circular or crescent-shaped.

[0066] The outermost position of the fitting leg portion 71c in the radial direction of the fitting protrusion 71 may be different from the position of the outer peripheral surface 71a of the fitting protrusion 71. At least one fitting leg portion 71c may be omitted. In this case, at least one fitting leg portion 71c may be changed to a motor-side bolt fastening portion 71b.

[0067] The total number of motor-side bolt fastening portions 71b and fitting leg portions 71c may be at least 3. For example, the number of motor-side bolt fastening portions 71b may be two, and the number of fitting leg portion 71c may be one.

[0068] At least one of the motor-side bolt fastening portions 71b may be omitted. In this case, at least one of the motor-side bolt fastening portions 71b may be changed to a fitting leg portion 71c. If all of the motor-side bolt fastening portions 71b are changed to fitting leg portions 71c, the bolt fastening portion 65 may be provided in a different position.

[0069] The extension portion 72 may be omitted. In other words, the portion where the fitting protrusion 71 is spigot-fitted to the peripheral projection 82 may be exposed to the outside. The orientation in which the column shaft 15, motor 30, and transmission mechanism 40 are arranged may be changed as appropriate. For example, the angle θ1 may be a right angle or an obtuse angle. The angle θ2 may be an acute angle or an obtuse angle. The angle θ3 may be a right angle or an obtuse angle. For example, the transmission mechanism 40 may be arranged in an orientation in which the output portion 34a is accommodated from above the motor 30 in the direction of gravity.

[0070] The transmission mechanism 40 is not limited to a worm reduction mechanism and may be changed as appropriate, for example, to a belt-type reduction mechanism using a ball screw mechanism, etc. The operating member 11 is not limited to a steering wheel and may be, for example, a joystick.

[0071] In the above-described embodiments, the motor 30 may be configured to transmit motor torque to the steered shaft 14. The above-described embodiments may be, for example, a steer-by-wire vehicle steering device in which the power transmission path between the operation member 11 and the steered wheels 12 is mechanically separated. In this case, the motor torque of the motor 30 may be used as at least one of a reaction force applied to the operation member 11 and a steering force for steering the steered wheels 12. Alternatively, the above-described embodiments may be a rear-wheel vehicle steering device for steering the left and right rear wheels of a vehicle. In this case, the motor torque of the motor 30 may be used as a steering force for steering the left and right rear wheels.

Claims

1. A vehicle steering device having an operation mechanism to which an operation member of a vehicle that is operated to steer steered wheels of the vehicle is connected, a motor configured to generate torque for varying the operating force required to operate the operating member; a transmission mechanism configured to transmit torque generated by the motor to the operation mechanism, the motor has a motor housing that accommodates a stator and a rotor, an output shaft that rotates integrally with the rotor has an output portion that protrudes from the motor housing to the outside, the transmission mechanism includes a mechanism housing that houses a part of the operation mechanism and the output portion so as to connect the part of the operation mechanism to the output shaft; the motor housing has a motor-side fitting portion that fits into the mechanism housing in an axial direction along the axis of the output shaft, the mechanism housing has a mechanism-side fitting portion that fits into the motor-side fitting portion in the axial direction, the mechanism-side fitting portion and the motor-side fitting portion are fastened together in the axial direction by a bolt, the mechanism-side fitting portion and the motor-side fitting portion are disposed radially outward of the rotor as viewed in the axial direction, the mechanism-side fitting portion has an opposing portion that faces the motor-side fitting portion in the axial direction, and a peripheral protrusion that extends in the axial direction from a periphery of the opposing portion, the motor-side fitting portion has a fitting end surface that abuts against the opposing portion in the axial direction, a non-abutting end surface that faces the opposing portion but does not abut against the opposing portion in the axial direction, and a fitting side surface that is disposed inside the peripheral protrusion in the radial direction of the output shaft and abuts against the peripheral protrusion, the fitting end surface has a plurality of end surfaces that are discontinuously provided along the circumferential direction of the output shaft, The non-contact end surface is provided between the plurality of end surfaces along the circumferential direction of the output shaft.

2. the motor-side fitting portion has a plurality of bolt fastening portions that are fastened to the mechanism-side fitting portion in the axial direction, 2. The vehicle steering device according to claim 1, wherein the plurality of end faces include a plurality of bolt fastening surfaces provided at the bolt fastening portions, and a plurality of normal end faces provided at portions of the motor side fitting portion other than the bolt fastening portions.

3. each of the motor-side fitting portion and the mechanism-side fitting portion has a circular shape when viewed in the axial direction; The vehicle steering apparatus according to claim 2 , wherein, in a radial direction of the motor-side fitting portion, an innermost position of the plurality of normal end surfaces is located outside an innermost position of the plurality of bolt fastening surfaces.

4. 4. The vehicle steering apparatus according to claim 2, wherein the bolt fastening surfaces and the normal end surfaces are alternately arranged along the circumferential direction of the output shaft.

5. 5. The vehicle steering apparatus according to claim 4, wherein the bolt fastening surface and the normal end surface are arranged to be offset from each other by an equal angle along the circumferential direction of the output shaft.