Vehicle steering system

Abstract

The invention relates to a vehicle steering system. A vehicle steering device (10) includes a motor (30) and a transmission mechanism (40). The motor (30) has a motor housing (31). The transmission mechanism (40) has a mechanism housing (40). The motor (30) is disposed such that an output part (34a) of an output shaft (34) protrudes downward from the gravity direction of a motor housing (31). The transmission mechanism (40) is configured to accommodate the output part (34a) from the lower side of the gravity direction of the motor (30). A motor-side fitting part (31d) of the motor housing (31) has an extending protrusion (72) disposed on the outside in the radial direction of an output shaft (34) of a mechanism-side fitting part (41d) of the mechanism housing (41). The extending protruding part (72) extends from the motor housing (31) to the lower side of the gravity direction in a manner that the axial position of the extending protruding part (72) is overlapped with the mechanism side embedding part (41d).

Description

Technical Field

[0001] The present invention relates to a vehicle steering device. Background Art

[0002] For example, as disclosed in Patent Document 1, there is a vehicle steering device configured to apply an auxiliary force generated by the torque of a motor to a column shaft. The motor is connected to the column shaft via a reduction mechanism. The reduction mechanism is tightly connected to the motor in order to transmit the torque of the motor to the column shaft. When the motor and the reduction mechanism are tightly connected, there is a concern that water may penetrate into the interior of the reduction mechanism through the gap between the mutually fastening parts. In this regard, for example, Patent Document 2 discloses a structure that can suppress the intrusion of water into the interior of an external device through the gap between the mutually fastening parts by providing an O-ring between the motor and the external device.

[0003] Patent Document 1: Japanese Patent Application Laid-Open No. 2012-90496

[0004] Patent Document 2: International Publication No. 2018 / 180923

[0005] In a vehicle steering system such as that disclosed in Patent Document 1, an O-ring is provided between the fastening portions of the motor and the reduction mechanism, as disclosed in Patent Document 2, thereby preventing water from entering the reduction mechanism through the gap between the fastening portions. In other words, an additional structure such as an O-ring must be provided to prevent water from entering the reduction mechanism. Summary of the Invention

[0006] A vehicle steering system according to one embodiment of the present invention includes an operating mechanism connected to a vehicle operating member operated to steer the vehicle's steering wheels. The vehicle steering system includes a motor configured to generate torque for varying the operating force required to operate the operating member; and a transmission mechanism configured to transmit the torque generated by the motor to the operating mechanism. The motor includes a motor housing that houses a stator and a rotor. An output shaft that rotates integrally with the rotor includes an output portion that protrudes from the motor housing. The transmission mechanism includes a mechanism housing that houses a portion of the operating mechanism and connects the output portion to the output shaft. The motor is configured such that the axis of the output shaft intersects the horizontal direction, and the output portion protrudes from the lower side of the motor housing in the direction of gravity. The transmission mechanism is configured to house the output portion from the lower side of the motor in the direction of gravity. The motor housing includes a motor-side mating portion that engages with the mechanism housing in the axial direction of the output shaft. The mechanism housing includes a mechanism-side mating portion that engages with the motor-side mating portion in the axial direction. The motor-side fitting portion has an extended protrusion that is arranged radially outward of the output shaft of the mechanism-side fitting portion when viewed from the axial direction, and the extended protrusion extends from the motor housing toward the lower side in the gravity direction in a manner such that the axial position of the extended protrusion overlaps with the mechanism-side fitting portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 It is a diagram showing a schematic configuration of a vehicle steering system according to an embodiment.

[0008] Figure 2 Yes Figure 1 A diagram showing the simplified structure of the motor and transmission mechanism.

[0009] Figure 3 Yes Figure 1 A cross-sectional view of the structure of the motor and transmission mechanism.

[0010] Figure 4 Yes Figure 3 A three-dimensional diagram of the structure of the motor housing.

[0011] Figure 5 Yes Figure 3 A top view of the structure of the motor housing.

[0012] Figure 6 Yes Figure 3 A three-dimensional diagram of the structure of the worm housing.

[0013] Figure 7 yes Figure 3 Schematic diagram of the structure of the bolt fastening portion, that is, the portion including the bolt fastening surface.

[0014] Figure 8 is included Figure 3 Schematic diagram of the structure of a typical end face portion.

[0015] Figure 9 is included Figure 3 Schematic diagram of the structure of the end surface portion of the connecting portion. DETAILED DESCRIPTION

[0016] A vehicle steering system according to one embodiment will be described with reference to the accompanying drawings.

[0017] like Figure 1 As shown, the electric power steering device 10 is an example of a vehicle steering control device mounted on a vehicle. The electric power steering device 10 has an operating mechanism 13 and a steering shaft 14. The operating mechanism 13 and the steering shaft 14 constitute a power transmission path between the operating member 11 of the vehicle and the steering wheels 12, 12 of the vehicle. The operating member 11 is, for example, a steering wheel. The operating mechanism 13 includes a column shaft 15, an intermediate shaft 16, and a pinion shaft 17 that 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 operating member 11 and the intermediate shaft 16. The intermediate shaft 16 connects the column shaft 15 and the pinion shaft 17. The steering shaft 14 is along the width direction of the vehicle body, that is, Figure 1 The steering shaft 14 is housed in a housing 18 fixed to the vehicle body. The steered wheels 12, 12 are connected to both ends of the steering shaft 14 via tie rods 19, 19, respectively.

[0018] Pinion teeth 17a of the pinion shaft 17 mesh with rack teeth 14a of the steering shaft 14. As a result, the steering shaft 14 moves along its axis in conjunction with the rotation of the operating member 11, thereby changing the steering angle of the steered wheels 12, 12.

[0019] About the operating mechanism

[0020] like Figure 1 as well as Figure 2 As shown, the operating mechanism 13 includes an assist mechanism 20. The assist mechanism 20 is a structure for applying an assist force to the steering shaft 14. The assist force is a driving force applied to the operating member 11 to change the operating force required to operate the operating member 11. The assist mechanism 20 includes a motor 30 and a transmission mechanism 40. The motor 30 is fixed to the outside of the transmission mechanism 40.

[0021] 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. That is, the motor 30 is fixed to the vehicle body B via the steering column 13a and the transmission mechanism 40.

[0022] About Motors

[0023] like Figure 3 As shown, the motor 30 is the source of the assist force. The motor 30 is, for example, a three-phase brushless motor. The motor 30 includes a motor housing 31, a stator 32, a rotor 33, an output shaft 34, and a control device 50. The motor housing 31 houses the stator 32 and rotor 33. The output shaft 34, which rotates integrally with the rotor 33, has a first end, or output portion 34a, protruding from the exterior of the motor housing 31.

[0024] The control device 50 is integrally provided in the motor 30. The control device 50 obtains the detection results of various sensors mounted on the vehicle as information indicating the driver's requirements or the driving status, and controls the motor 30 based on the obtained information. Sensors include, for example, a torque sensor, a vehicle speed sensor, and a rotation angle sensor. The torque sensor is provided in the middle of 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 auxiliary control to generate an auxiliary force corresponding to the operating torque and the vehicle speed by controlling the power supply to the motor 30. The control device 50 uses the rotation angle of the output shaft 34 detected by the rotation angle sensor to perform vector control on the motor 30.

[0025] About the delivery organization

[0026] like Figure 3 As shown, the transmission mechanism 40 reduces the speed 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 includes a worm housing 41, a worm shaft 42, and a worm wheel 43. The worm housing 41 houses a portion of the column shaft 15 and also houses the worm shaft 42 and the worm wheel 43. In this embodiment, the worm housing 41 is an example of a mechanism housing.

[0027] The first end of the worm shaft 42, namely the joint 42a, is connected to the output shaft 34, namely the motor 30, via the output portion 34a. The worm shaft 42 has a worm portion 42c between the joint 42a and the second end, namely the shaft end 42b, on the opposite side of the joint 42a. The worm wheel 43 meshes 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 connected to the worm wheel 43 in a state where it is inserted into the through hole 43a so as to be able to rotate as a whole. 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, namely the transmission mechanism 40, between the first end 15a and the second end 15b on the opposite side of the first end 15a. That is, the transmission mechanism 40 connects the column shaft 15 and the output shaft 34 via the worm shaft 42 and the worm wheel 43.

[0028] Motor and Transmission Mechanism Configuration

[0029] exist Figures 1 to 3 , a horizontal line X extending in the horizontal direction 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. Angle θ1 is, for example, an acute angle. That is, the axis Z1 intersects the horizontal line X in such a way that the first end 15a is arranged on the upper side in the direction of gravity and the second end 15b is arranged on the lower side in the direction of gravity. The axis of the worm wheel 43 is consistent with the axis Z1. In this case, the axis Z2 of the worm shaft 42 forms an angle θ2 with the axis Z1. Angle θ2 is, for example, a right angle. That is, the axis Z2 intersects the horizontal line X and the axis Z1 in such a way that the joint 42a is arranged on the upper side in the direction of gravity and the shaft end 42b is arranged on the lower side in the direction of gravity. In addition, the axis Z2 passes through the center of gravity G of the worm wheel 43 and forms an angle θ3 with the center of gravity line Z1a perpendicular to the axis Z1. Angle θ3 is, for example, an acute angle. That is, the position of the transmission mechanism 40 in the circumferential direction of the axis Z1 is adjusted so that the axis Z2 and the center of gravity line Z1a form an angle θ3.

[0030] Thus, the motor 30 is arranged so that the axis Z2 of the output shaft 34 intersects 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 arranged so that the output portion 34a is housed from the lower side in the direction of gravity of the motor 30.

[0031] Motor and Transmission Mechanism Structure

[0032] like Figure 3 As shown, the motor housing 31 is cylindrical with an open first end 31a located upward in the direction of gravity. The motor housing 31 is made of a metal such as aluminum. It includes a main body 31c and a motor-side fitting 31d. The main body 31c is cylindrical, for example. The motor-side fitting 31d is located at the second end 31b of the main body 31c and forms the bottom of the motor housing 31.

[0033] The stator 32 is fixed to the inner circumference of the main body 31c. The stator 32 includes a stator core 32a and coils 32b. The stator core 32a is cylindrical, for example. The stator core 32a has a plurality of teeth 32c protruding from its inner circumference. The coils 32b are wound around the plurality of teeth 32c.

[0034] The rotor 33 is disposed on the inner circumference of the stator 32, with a gap therebetween in the radial direction. 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 circumference of the output shaft 34 so as to be rotatable together with the output shaft 34. The output shaft 34 is rotatably supported by the motor housing 31 via bearings 34b and 34c. The magnets 33b are arranged, for example, along the circumference of the rotor core 33a. The magnetic poles of the magnets 33b are arranged so that north and south poles alternate in the circumferential direction of the rotor core 33a.

[0035] The bearing 34b is fixed to the cover portion 60 mounted on the first end 31a of the main body 31c. The cover portion 60 is in the shape of a circular plate. The cover portion 60 is made of a metal such as aluminum. The first end 31a of the main body 31c and the cover portion 60 are fitted into a recess. In addition, the first end 31a of the main body 31c and the cover portion 60 are fastened to each other outside the motor housing 31 by bolts or the like. As a result, the opening of the first end 31a of the main body 31c is closed by the cover portion 60. The cover portion 60 supports the second end of the output shaft 34 on the side opposite to the output portion 34a at the center in the radial direction.

[0036] The bearing 34c is fixed to the motor-side fitting portion 31d of the main body 31c. The motor-side fitting portion 31d has an axial hole 31e at its radial center. The motor-side fitting portion 31d supports the output shaft 34 near its first end at its radial center. The output portion 34a protrudes from the motor housing 31 through the axial hole 31e of the motor-side fitting portion 31d.

[0037] The control device 50 is provided on the opposite side of the main body 31c relative to the cover 60. The control device 50 includes a substrate 50a and a plurality of electronic components 50b. The substrate 50a is fixed to the cover 60 so that its first surface in the thickness direction faces the cover 60. The plurality of electronic components 50b are mounted on both surfaces of the substrate 50a. The plurality of electronic components 50b include a rotation angle sensor. The rotation angle sensor is, for example, arranged 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 cover 60. The cover 61 is made of a metal such as aluminum, for example.

[0038] like Figure 3 As shown, the worm housing 41 is formed into a shape that connects the side of the cylinder open on the upper side in the direction of gravity of the axis Z1 and the side of the cylinder open on the upper side in the direction of gravity of the axis Z2. Figure 3 That is, the lower side of the gravity direction of the axis Z1 is along the axis Z1. Figure 3 The gravity direction of axis Z2 is along the inner side of the paper. Figure 3 That is, the lower side of the gravity direction of the axis Z2 is along the axis Z2. Figure 3 The lower side of the worm housing 41 is made of a metal such as aluminum. The worm housing 41 has a first main body 41a and a second main body 41b. The first main body 41a is, for example, cylindrical with an axial length along the axis Z1 and a diameter larger than the axial length. The diameter of the first main body 41a is larger than the diameter of the worm wheel 43. The first main body 41a houses the worm wheel 43, that is, a part of the column shaft 15. The second main body 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 main body 41b is larger than the axial length of the worm shaft 42. The second main body 41b houses the worm shaft 42, that is, the output portion 34a. The interior of the first main body 41a and the interior of the second main body 41b are connected to each other via the connecting portion 41c. The worm shaft 42 and the worm wheel 43 are meshed with each other via the connecting portion 41c.

[0039] A fixing member BR2 is provided on the lower side of the first main body 41a in the direction of gravity. A main body cover 62 is provided on the upper side of the first main body 41a in the direction of gravity. The main body cover 62 houses the portion where the torque sensor of the column shaft 15 is installed. The main body cover 62 closes the opening on the upper side of the first main body 41a in the direction of gravity. The main body cover 62 has an axial hole 62a at the center in the radial direction. The column shaft 15 enters the interior of the worm housing 41 through the axial hole 62a of the main body cover 62.

[0040] A main body cover 63 is provided on the lower side of the second main body 41b in the direction of gravity. The main body cover 63 closes the opening on the lower side of the second main body 41b 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, that is, on the opposite side of the main body cover 63. The mechanism-side fitting portion 41d is fitted into the recess of 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 from the lower side of the axis Z2 in the direction of gravity by a plurality of bolts 64 in a state of being fitted into each other. There are, for example, two bolt fastening portions 65 formed by fastening with the bolts 64. The mechanism-side fitting portion 41d includes a portion connected to the first main body 41a.

[0041] The worm shaft 42 is rotatably supported by the second main body 41b via bearings 42d and 42e. The worm shaft 42 is inserted into the second main body 41b from above in the direction of gravity so that the shaft end 42b is close to the main body cover 63.

[0042] The bearing 42d is fixed to the second main body 41b near the main body cover 63. The bearing 42e is fixed to the mechanism-side fitting portion 41d of the second main body 41b. The mechanism-side fitting portion 41d has an axial hole 41e at its radial center. The mechanism-side fitting portion 41d supports the worm shaft 42 at its radial center near the joint 42a. The joint 42a protrudes from the exterior of the worm housing 41 through the axial hole 41e of the mechanism-side fitting portion 41d.

[0043] <Regarding the structure of the motor-side fitting>

[0044] like Figure 4 as well as Figure 5 As shown, the motor-side fitting portion 31d of the motor housing 31 is located at the second end 31b of the main body 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 includes a fitting protrusion 71, an extending protrusion 72, and a groove 73.

[0045] The fitting protrusion 71 extends axially from the second end 31b of the main body 31c. The fitting protrusion 71 extends continuously along the circumferential direction of the main body 31c. The fitting protrusion 71 is located radially inward of the outer peripheral edge of the main body 31c. Figure 3 In the case of the motor 30 shown, the engaging projection 71 is arranged radially outward of the rotor 33 when viewed from the axial direction. The engaging projection 71 is arranged so as to overlap the stator 32 when viewed from the axial direction. The outer peripheral surface 71a of the engaging projection 71 is a cylindrical surface that is perpendicular to the radial direction and extends parallel to the axial direction.

[0046] The mating protrusion 71 is provided with 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 axially more than 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 angles, i.e., 90 degrees, offset from each other along the circumferential direction. Furthermore, the two motor-side bolt-fastening portions 71b are arranged at equal angles, i.e., 180 degrees, offset from each other along the circumferential direction. Furthermore, the two mating legs 71c are arranged at equal angles, i.e., 180 degrees, offset from each other along 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 provided discontinuously along the outer peripheral surface 71a.

[0047] The motor-side bolt-fastening portion 71b is cylindrical. With respect to the radial direction of the mating protrusion 71, the outermost position of the motor-side bolt-fastening portion 71b coincides with the outer circumferential surface 71a of the mating protrusion 71. With respect to the radial direction of the mating protrusion 71, the innermost position of the motor-side bolt-fastening portion 71b is located further inward than the inner circumferential surface of other parts of the mating protrusion 71. A bolt-fastening hole 71e is provided at the center of the motor-side bolt-fastening portion 71b, as viewed axially. The bolt-fastening hole 71e extends, for example, axially through the motor-side bolt-fastening portion 71b and reaches the main body 31c. The motor-side bolt-fastening portion 71b has a bolt-fastening surface 71f surrounding 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 mating end surface. Furthermore, the outer circumferential surface 71a of the mating protrusion 71 is an example of a mating side surface.

[0048] The cross-sectional shape of the mating leg 71c perpendicular to the axial direction is a crescent-shaped columnar body. With respect to the radial direction of the mating protrusion 71, the outermost position of the mating leg 71c coincides with the outer peripheral surface 71a of the mating protrusion 71. With respect to the radial direction of the mating protrusion 71, the innermost position of the mating leg 71c is further outward than the innermost position of the motor-side bolt fastening portion 71b. The mating leg 71c has a crescent-shaped normal end surface 71g. When viewed from the axial direction, the diameter of the circle of the normal end surfaces 71g of the two mating legs 71c that contacts the radial innermost portion is larger than the diameter of the circle of the two bolt fastening surfaces 71f that contacts the radial innermost portion. In this embodiment, the normal end surface 71g is an example of a mating end surface.

[0049] The connecting portion 71d extends in an arcuate shape to connect the motor-side bolt fastening portion 71b and the fitting leg portion 71c, which are adjacent to each other in the circumferential direction. With respect to 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. With respect to 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 those where the motor-side bolt fastening portion 71b is provided. The connecting portion 71d has an arcuate end face 71h. When viewed from the axial direction, the diameter of the circle of the four end faces 71h in contact with the radial innermost portion coincides with the diameter of the circle of the normal end face 71g in contact with the radial innermost portion.

[0050] The extension 72 extends axially 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 distal end 72b. The extension 72 is located radially outward of the mating protrusion 71.

[0051] The groove 73 is provided in the radial direction of the main body 31c, between the mating protrusion 71 and the extended protrusion 72. The inner wall surface 73a of the groove 73 is formed by the outer circumferential surface 71a of the mating protrusion 71 and the inner circumferential surface 72a of the extended protrusion 72. The bottom surface 73b of the groove 73 connects the outer circumferential surface 71a of the mating protrusion 71 and the inner circumferential surface 72a of the extended protrusion 72. The groove 73 has a depth in the axial direction. The depth of the groove 73 corresponds to the axial length of the extended protrusion 72 along the main body 31c. The radial width of the groove 73 increases as the position is farther away from the bottom surface 73b.

[0052] <Regarding the structure of the fitting portion on the mechanism side>

[0053] like Figure 6 As shown, the mechanism-side fitting portion 41d of the worm housing 41 is located on the side of the second main body portion 41b opposite the main body cover 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 orthogonal to the axis Z2. The mechanism-side fitting portion 41d includes an opposing portion 81 and a peripheral protrusion 82.

[0054] The opposing portion 81 is annular when viewed from the axial direction. The opposing portion 81 extends radially outward from the peripheral edge of the axial hole 41e of the mechanism-side fitting portion 41d. The opposing portion 81 extends radially outward from the outer peripheral edge of the end portion of the second main body portion 41b. In relation to the motor 30, the opposing portion 81 extends to the radially outer side of the rotor 33 when viewed from the axial direction. In relation to the motor 30, the opposing portion 81 overlaps with the stator 32 when viewed from the axial direction. The opposing portion 81 has an opposing surface 81a that is orthogonal to the axial direction. Two bolt fastening holes 81b are provided in the opposing portion 81. The bolt fastening hole 81b penetrates the opposing portion 81 in the axial direction, for example. The two bolt fastening holes 81b are arranged to be staggered at equal angles, i.e., 180 degrees, from each other in the circumferential direction.

[0055] The peripheral protrusion 82 extends axially from the outer peripheral edge of the opposing portion 81. The peripheral protrusion 82 extends continuously along the circumference of the opposing portion 81. The peripheral protrusion 82 is positioned radially outward of the rotor 33 as viewed axially relative to the motor 30. The peripheral protrusion 82 is positioned relative to the motor 30 so as to include a portion overlapping with the stator 32 as viewed axially. The inner circumferential surface 82a of the peripheral protrusion 82 is a cylindrical surface that extends orthogonally to the radial direction and parallel to the axial direction.

[0056] like Figures 6 to 9As shown, the peripheral protrusion 82 has a groove insertion portion 82c. The groove insertion portion 82c has a front end 82b, a gradient portion 82d, and a thin-walled portion 82e. The front end 82b of the groove insertion portion 82c is also the front end of the peripheral protrusion 82. The gradient portion 82d is the portion between the root 82f and the front end 82b of the peripheral protrusion 82, and has a radial thickness that gradually decreases toward the front end 82b. The thin-walled portion 82e is the portion between the gradient portion 82d and the front end 82b of the peripheral protrusion 82, and has a radial thickness that is constant toward the front end 82b. The radial thickness of the thin-walled portion 82e is the smallest in the peripheral protrusion 82. The portion of the peripheral protrusion 82 other than the groove insertion portion 82c has an outer peripheral surface 82g that is orthogonal to the radial direction. The outer peripheral surface 82g is a cylindrical surface that extends parallel to the axial direction.

[0057] like Figures 7 to 9 As shown, the axial length Lw from the base 82f to the tip 82b of the peripheral protrusion 82 relative to the motor-side fitting portion 31d is smaller than the axial length Lm from the bolt-fastening surface 71f or the normal end surface 71g to the bottom surface 73b of the groove 73. The outer circumferential surface 82g of the peripheral protrusion 82 overlaps with the tip 72b of the extended protrusion 72 when viewed axially. The diameter Rw of the inner circumferential surface 82a of the peripheral protrusion 82 relative to the motor-side fitting portion 31d is less than the diameter Rm of the outer circumferential surface 71a of the fitting protrusion 71. The radial thickness Tw of the thin-walled portion 82e of the groove insertion portion 82c relative to the motor-side fitting portion 31d is smaller than the minimum radial width Tm of the groove 73.

[0058] <Regarding the Fitting Between the Motor-Side Fitting and the Mechanism-Side Fitting>

[0059] like Figure 3 、 Figures 7 to 9 As shown, the motor-side fitting portion 31d and the mechanism-side fitting portion 41d are fitted together by the fitting protrusion 71 and the peripheral protrusion 82 being fitted into a recess. 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. As a result, the radial position of the fitting protrusion 71 and the peripheral protrusion 82 when fitting into the recess is determined. The fitting protrusion 71 abuts against the opposing portion 81 in the axial direction. As a result, the axial position of the fitting protrusion 71 and the peripheral protrusion 82 when fitting into the recess is determined. The portion of the recess fitting is arranged so that, when viewed from the axial direction, it is radially outward of the rotor 33 and includes a portion overlapping with the stator 32. 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 an example of abutting surfaces.

[0060] Figure 7The schematic diagram shows the end surface structure of the area including the motor-side bolt-fastening portion 71b when the motor is engaged with the recess. In this case, the outer peripheral surface 71a of the engaging protrusion 71 radially contacts the entire inner peripheral surface 82a of the peripheral protrusion 82. Furthermore, the bolt-fastening surface 71f axially contacts the opposing surface 81a.

[0061] Furthermore, 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 and 81b are axially connected. Bolts 64 are inserted through the axially connected bolt-fastening holes 71e and 81b from the mechanism-side fitting portion 41d toward the motor-side fitting portion 31d. This fastens the motor-side fitting portion 31d and the mechanism-side fitting portion 41d. The motor-side bolt-fastening portion 71b, including the bolt-fastening hole 71e, and the bolt-fastening hole 81b together constitute a single bolt-fastening portion 65. The two bolt-fastening portions 65 are located radially inward of the portion where the fitting protrusion 71 and the recessed circumferential protrusion 82 engage.

[0062] Figure 8 The schematic diagram shows the end face structure of the area including the mating leg 71c when the mating recess is engaged. In this case, the outer peripheral surface 71a of the mating protrusion 71 abuts the entire inner peripheral surface 82a of the peripheral protrusion 82 in the radial direction. Furthermore, the normal end face 71g abuts the opposing surface 81a in the axial direction. In the radial direction of the mating protrusion 71, the range of abutment between the normal end face 71g and the opposing surface 81a is smaller than the range of abutment between the bolt-fastening surface 71f and the opposing surface 81a. This is because the innermost position of the mating leg 71c in the radial direction of the mating protrusion 71 is further outward than the innermost position of the motor-side bolt-fastening portion 71b.

[0063] Figure 9 The end face structure of the portion of the connecting portion 71d that includes the recessed engagement is schematically shown. In the portion of the connecting portion 71d, the outer circumferential surface 71a of the engaging protrusion 71 radially abuts a portion of the inner circumferential surface 82a of the peripheral protrusion 82. In other words, while the end face 71h of the connecting portion 71d axially opposes the opposing surface 81a, it does not abut the opposing surface 81a axially. In the radial direction of the engaging protrusion 71, the range of abutment between the outer circumferential surface 71a and the inner circumferential surface 82a is smaller than the range of abutment between the outer circumferential surface 71a and the inner circumferential surface 82a of the motor-side bolt-fastening portion 71b and the engaging leg 71c. This is because the axial protrusion of the connecting portion 71d is smaller than the axial protrusion of the motor-side bolt-fastening portion 71b and the engaging leg 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 of the connecting portion 71d only needs to be large enough to allow for radial positioning when the fitting protrusion 71 and the peripheral protrusion 82 are fitted into the recess.

[0064] In addition, if Figures 7 to 9 As shown, 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 state, the tip 82b, when inserted into the groove 73, has an axial gap Adg with the groove 73 bottom surface 73b. This gap Adg corresponds 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 surface 71g to the groove bottom surface 73b. The gap Adg is smaller than the axial length Ln from the groove bottom surface 73b to the tip 72b of the extension 72. In other words, the extension 72 extends downward in the direction of gravity, so that the axial position of the extension 72 overlaps with a portion of the thin-walled portion 82e, namely, the peripheral protrusion 82.

[0065] Furthermore, when inserted into the groove 73, the thin-walled portion 82e faces the inner wall surface 73a of the groove 73, that is, the outer peripheral surface 71a of the fitting protrusion 71 and the inner peripheral surface 72a of the extended protrusion 72, with a radial gap Rdg therebetween. The gap Rdg is the sum of the radial gaps between the thin-walled portion 82e and the outer peripheral surface 71a, and the radial gaps between the thin-walled portion 82e and the inner peripheral surface 72a. The gap Rdg is greater than the difference 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 (gap Rdg1 + gap Rdg2).

[0066] <Function of this embodiment>

[0067] like Figure 3 、 Figures 7 to 9 As shown, the extended protrusion 72 is located on the upper side relative to the peripheral protrusion 82 in the direction of gravity and is located radially outward from the outer peripheral surface 82g of the peripheral protrusion 82. The peripheral protrusion 82 is the radially outermost portion of the mechanism-side interlocking portion 41d. The extended protrusion 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 extended protrusion 72 covers the peripheral protrusion 82, i.e., the mechanism-side interlocking portion 41d, from the upper side in the direction of gravity. In the interlocking protrusion 71, the portion that is interlocked with the recess of the peripheral protrusion 82 is the radially inner portion of the extended protrusion 72. Thus, the extended protrusion 72 can cover the portion of the interlocking protrusion 71 that is interlocked with the recess of the peripheral protrusion 82 from the outside.

[0068] <Effects of this embodiment>

[0069] (1-1) The extended protrusion 72 can cover the area where the mating protrusion 71 and the peripheral protrusion 82 are recessed and fitted together from the outside. Therefore, it is possible to prevent water from entering the interior of the transmission mechanism 40 through the gap between the mating protrusion 71 and the peripheral protrusion 82. This eliminates the need for additional structures such as O-rings to be placed in the area where the mating protrusion 71 and the peripheral protrusion 82 are recessed and fitted together.

[0070] (1-2) Figure 7 As shown, the two bolt fastening portions 65 are located radially inward of the portion where the fitting protrusion 71 and the peripheral protrusion 82 are recessed and fitted.

[0071] (1-3) Figures 7 to 9 As shown, when the front end 82b is inserted into the groove 73, it has an axial gap Adg and faces the bottom surface 73b of the groove 73. This gap Adg can absorb axial assembly tolerances when assembling the motor 30 and the transmission mechanism 40. This effectively improves assembly efficiency.

[0072] (1-4) Figures 7 to 9 As shown, when inserted into groove 73, thin-walled portion 82e has a radial clearance Rdg and faces inner wall surface 73a of groove 73, i.e., outer circumferential surface 71a of fitting protrusion 71, and inner circumferential surface 72a of extension 72. This clearance Rdg can absorb axial assembly tolerances during assembly of motor 30 and transmission mechanism 40, effectively improving assembly efficiency.

[0073] (1-5) Even if water flows around the outside of the extended protrusion 72 , the gaps Adg and Rdg can suppress the occurrence of capillary phenomena, etc. This can more appropriately suppress the intrusion of water into the transmission mechanism 40 .

[0074] (1-6) Figure 3 As shown, the motor-side fitting portion 31d and the mechanism-side fitting portion 41d are fitted together at a position radially outside the rotor 33 and overlapping the stator 32 when viewed from the axial direction. Thus, the portion where the fitting protrusion 71 and the peripheral protrusion 82 are recessed and fitted together ensures the axial rigidity of the motor 30.

[0075] On the other hand, Figure 9As shown, the axial engagement range between the motor-side engagement portion 31d and the mechanism-side engagement portion 41d is smaller at locations where the bolt fastening surface 71f and the normal end surface 71g are absent, i.e., where the connecting portion 71d is present, than at other locations. Consequently, the rigidity associated with the engagement between the motor-side engagement portion 31d and the mechanism-side engagement portion 41d can be reduced at locations where the connecting portion 71d is present. Consequently, vibration generated by radial expansion and contraction of the motor housing 31 is less likely to be transmitted to the mechanism-side engagement portion 41d, i.e., the transmission mechanism 40. Consequently, a decrease in the durability of the motor housing 31, i.e., the motor 30, can be suppressed.

[0076] (1-7) Figure 7 as well as Figure 8 As shown, the bolt fastening surface 71f and the normal end surface 71g are in contact with the facing 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.

[0077] (1-8) Figure 7 as well as Figure 8 As shown, in the radial direction of the mating protrusion 71, the innermost position of the mating leg portion 71c is located outward from the innermost position of the motor-side bolt-fastening portion 71b. Therefore, in the radial direction of the mating protrusion 71, the range of contact between the normal end surface 71g and the opposing surface 81a is smaller than the range of contact between the bolt-fastening surface 71f and the opposing surface 81a. This reduces the rigidity associated with the mating between the motor-side mating portion 31d and the mechanism-side mating portion 41d, compared to a case where the contact range between the normal end surface 71g and the opposing surface 81a is the same as the contact range between the bolt-fastening surface 71f and the opposing surface 81a. As a result, vibrations generated by radial expansion and contraction of the motor housing 31 are less likely to be transmitted to the mechanism-side mating portion 41d, i.e., the transmission mechanism 40.

[0078] (1-9) Figure 5 As shown, the motor-side bolt-fastening portions 71b and the fitting legs 71c are alternately arranged at equal intervals in the circumferential direction. This reduces the unevenness of the rigidity associated with the fitting between the motor-side fitting portion 31d and the mechanism-side fitting portion 41d at the portion where the fitting protrusion 71 and the peripheral protrusion 82 are recessed.

[0079] (1-10) Figure 5 As shown, the two motor-side bolt fastening portions 71b and the two fitting legs 71c are arranged at an equal angle, i.e., 90 degrees, in the circumferential direction. This allows for more appropriately suppressing any unevenness in rigidity associated with the fitting of the motor-side fitting portion 31d and the mechanism-side fitting portion 41d at the portion where the fitting protrusion 71 and the peripheral protrusion 82 are recessed.

[0080] <Other embodiments>

[0081] The above-mentioned embodiment can also be modified as follows: In addition, the following other embodiments can be combined with each other within the scope of no technical contradiction.

[0082] The gap Adg may be larger or smaller than that in the embodiment, for example, and can be appropriately changed. In this case, it is preferable that the gap Adg is equal to or larger than the length Ln.

[0083] The gap Rdg may be larger or smaller than that in the embodiment, for example, and can be changed as appropriate.

[0084] Gap Adg may also be absent. This also applies to gap Rdg. For example, when gaps Adg and Rdg are absent, thin-walled portion 82e, when inserted into groove 73, abuts inner wall surface 73a and bottom surface 73b. In this case, by adjusting the surface roughness of the mutually abutting surfaces of thin-walled portion 82e, inner wall surface 73a, and bottom surface 73b, a labyrinth structure can be constructed between the abutting surfaces.

[0085] The plurality of bolt-fastening portions 65 may be arranged radially outward of the portion where the fitting protrusion 71 and the peripheral protrusion 82 are recessedly fitted.

[0086] The outer peripheral surface 82g of the peripheral protrusion 82 may also coincide with the outer peripheral surface of the extension 72 when viewed from the axial direction. Alternatively, the outer peripheral surface 82g of the peripheral protrusion 82 may be located radially outward of the outer peripheral surface of the extension 72, provided that the portion where the fitting protrusion 71 and the recess of the peripheral protrusion 82 fit together can be covered from the outside.

[0087] The axial protrusion amount of the connecting portion 71d may be the same as the axial protrusion amount of the motor-side bolt fastening portion 71b and the fitting leg portion 71c. In this case, the axial protrusion amount of the fitting protrusion 71 is constant throughout the entire circumference.

[0088] The recessed engagement between the motor-side engagement portion 31d and the mechanism-side engagement portion 41d can also be achieved by recessed engagement between the peripheral protrusion 82 and the extended protrusion 72. In this case, the outer peripheral surface 82g of the peripheral protrusion 82 and the inner peripheral surface 72a of the extended protrusion 72 abut against each other in the radial direction. In other embodiments described herein, the outer peripheral surface 82g of the peripheral protrusion 82 and the inner peripheral surface 72a of the extended protrusion 72 serve as mutually abutting surfaces.

[0089] The motor-side bolt-fastening portion 71b and the fitting leg portion 71c may be arranged at different angles relative to each other along the circumferential direction. Specifically, the two motor-side bolt-fastening portions 71b may be arranged at an angle other than 180 degrees relative to each other along the circumferential direction. Furthermore, the two fitting leg portions 71c may be arranged at an angle other than 180 degrees relative to each other along the circumferential direction.

[0090] 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.

[0091] In the radial direction of the mating protrusion 71, the innermost position of the mating leg portion 71c may be located further inward than, or may coincide with, the innermost position of the motor-side bolt-fastening portion 71b. For example, if the innermost position of the mating leg portion 71c coincides with the innermost position of the motor-side bolt-fastening portion 71b in the radial direction of the mating protrusion 71, the bolt-fastening surface 71f and the normal end surface 71g may have the same shape. In this case, the bolt-fastening surface 71f and the normal end surface 71g may both be circular or crescent-shaped.

[0092] In the radial direction of the fitting protrusion 71 , the outermost position of the fitting leg portion 71 c may be different from the position of the outer peripheral surface 71 a of the fitting protrusion 71 .

[0093] At least one fitting leg portion 71c may be deleted. In this case, at least one fitting leg portion 71c may be replaced with the motor-side bolt fastening portion 71b.

[0094] The total number of the motor-side bolt-fastening portions 71b and the fitting leg portions 71c may be at least three. For example, the number of the motor-side bolt-fastening portions 71b may be two, and the number of the fitting leg portion 71c may be one.

[0095] At least one motor-side bolt-fastening portion 71b may be deleted. In this case, at least one motor-side bolt-fastening portion 71b may be replaced with a fitting leg portion 71c. If all motor-side bolt-fastening portions 71b are replaced with fitting legs 71c, the bolt-fastening portion 65 can be installed elsewhere.

[0096] The transmission mechanism 40 is not limited to the worm reduction mechanism, and may be, for example, a belt reduction mechanism using a ball screw mechanism, and can be modified as appropriate.

[0097] The operating member 11 is not limited to a steering wheel, and may be, for example, an operating lever.

[0098] The motor 30 in the above embodiment may be configured to transmit motor torque to the steering shaft 14 .

[0099] The above embodiment may also be, for example, an electric steering-type vehicle steering system that mechanically separates the power transmission path between the operating member 11 and the steered wheels 12. In this case, the motor torque of the motor 30 may be used as at least one of a reaction force applied to the operating member 11 and a steering force for steering the steered wheels 12. Alternatively, the above embodiment may be a rear-wheel vehicle steering system that steers the left and right rear wheels of the vehicle. In this case, the motor torque of the motor 30 may also be used as a steering force for steering the left and right rear wheels.

Claims

1. A vehicle steering system having an operating mechanism connected to an operating member of a vehicle operated to steer a steering wheel of the vehicle, the vehicle steering system comprising: a motor configured to generate a torque for changing an operating force required to operate the operating member; and a transmission mechanism configured to transmit the torque generated by the motor to the operating mechanism; The motor includes a motor housing for housing a stator and a rotor, and an output shaft that rotates integrally with the rotor includes an output portion that protrudes from the motor housing to the outside. The transmission mechanism includes a mechanism housing that houses a portion of the operating mechanism and houses the output portion in a manner that connects the portion of the operating mechanism to the output shaft. The motor is configured such that the axis of the output shaft intersects the horizontal direction, and the output portion protrudes from the lower side of the motor housing in the direction of gravity. The transmission mechanism is configured to receive the output portion from the lower side of the motor in the direction of gravity. The motor housing has a motor-side fitting portion that fits into the mechanism housing in the axial direction of the output shaft. The mechanism housing includes a mechanism-side fitting portion that fits with the motor-side fitting portion in the axial direction. The motor-side fitting portion has an extended protrusion that is arranged radially outward of the output shaft of the mechanism-side fitting portion when viewed from the axial direction, and the extended protrusion extends from the motor housing toward the lower side in the gravity direction in a manner such that the axial position of the extended protrusion overlaps with the mechanism-side fitting portion.

2. The vehicle steering system according to claim 1, wherein: The motor housing has a plurality of bolt fastening portions, and the mechanism housing has a plurality of bolt fastening portions, wherein the bolt fastening portions of the motor housing are fastened to the opposite bolt fastening portions of the mechanism housing in the axial direction. The motor-side fitting portion includes a fitting protrusion extending downward in the direction of gravity from the motor housing on the radially inner side of the output shaft relative to the extending protrusion. The mechanism-side fitting portion has a peripheral protrusion extending upward in the direction of gravity from the mechanism housing on the radially inner side of the output shaft relative to the extended protrusion. The outer peripheral surface of the above-mentioned fitting protrusion and the inner peripheral surface of the above-mentioned peripheral protrusion have abutting surfaces that abut each other. The plurality of bolt fastening portions are arranged radially inward of the output shaft relative to the abutment surface.

3. The vehicle steering system according to claim 2, wherein: The motor-side fitting portion includes a groove having a depth in the axial direction, the groove having an inner wall surface formed by the outer peripheral surface of the fitting protrusion and the inner peripheral surface of the extending protrusion. When the front end of the peripheral protrusion is inserted into the groove, the front end faces the bottom surface of the groove with a gap in the axial direction.

4. The vehicle steering system according to claim 2 or 3, wherein: The motor-side fitting portion includes a groove having a depth in the axial direction, the groove having an inner wall surface formed by the outer peripheral surface of the fitting protrusion and the inner peripheral surface of the extending protrusion. When the front end of the peripheral protrusion is inserted into the groove, the front end faces the inner wall surface with a gap in the radial direction of the output shaft.

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