Electric power steering system

Abstract

To provide an electric power steering device that can suppress complication of the shape of a housing.SOLUTION: An electric power steering device includes: a column shaft; an electric actuator configured to apply assist power to the column shaft; a sensor device 5 configured to detect a state quantity indicating a steering state; and a housing 23. The housing 23 is provided with a partition member 33 including a plate-shaped body portion 41 orthogonal to an axial direction of the column shaft. An inner space of the housing 23 is divided by the partition member 33 into a speed reducer housing space S1 in which a speed reducer 9 is housed and a sensor housing space S2 in which the sensor device 5 is housed. The speed reducer housing space S1 and the sensor housing space S2 are arranged side by side in the axial direction. A fixation unit 53 of the sensor device 5 is fixed to the body portion 41 in the axial direction.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an electric power steering device.

Background Art

[0002] For example, as described in Patent Document 1, an electric power steering device (EPS) including an electric actuator having a motor as a drive source is known. Such an electric power steering device includes a sensor device that detects a state quantity indicating a steering state by a driver, such as a steering torque or a steering angle. Then, by applying an assist force according to the steering state, the steering by the driver is appropriately assisted.

[0003] The sensor device of Patent Document 1 is provided around a shaft including an input shaft and an output shaft connected to the input shaft via a torsion bar. This sensor device includes a permanent magnet fixed to the input shaft, a magnetic yoke fixed to the output shaft, a cylindrical housing through which the shaft is inserted, and a sub-assembly. The sub-assembly is a unit in which various components for detecting a steering torque and a steering angle are attached to a base member, and is fixed to the housing.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the sensor device described in Patent Document 1, the peripheral wall of the housing is provided with an insertion opening perpendicular to the axial direction, and a pair of mounting walls extending in opposite directions from the peripheral edge of the insertion opening. The partial assembly is fixed to the housing by fastening a bolt to the mounting wall while a part of it is inserted into the housing through the insertion opening. In this conventional configuration, a pair of mounting walls are required on the outer surface of the housing, which tends to make its shape complex. [Means for solving the problem]

[0006] An electric power steering system that solves the above problems comprises a shaft that rotates in response to the driver's operation, an electric actuator that provides assist force to the shaft, a sensor device that detects a state quantity indicating the steering state, and a housing that houses the shaft, the electric actuator, and the sensor device. The electric actuator includes a motor and a reduction gear that reduces the rotation of the motor and transmits it to the shaft, the sensor device includes a fixed unit fixed to the housing, the housing includes a partition member having a plate-shaped main body that intersects the axial direction of the shaft, the partition member divides the internal space of the housing into a reduction gear housing space where the reduction gear is housed and a sensor housing space where the sensor device is housed, the reduction gear housing space and the sensor housing space are arranged side by side in the axial direction, and the fixed unit is fixed to the main body in the axial direction.

[0007] According to the above configuration, since the partition member has a main body that intersects with the axial direction, the fixing unit can be fixed to the partition member in the axial direction without having to separately provide a mounting wall or the like on the partition member for fixing the fixing unit of the sensor device. This makes it possible to suppress the complexity of the shape of the partition member, and consequently the shape of the housing.

[0008] In the electric power steering device described above, the shaft includes an input shaft and an output shaft connected to the input shaft via a torsion bar, and the sensor device further includes a sensor magnet that rotates integrally with either the input shaft or the output shaft, and a magnetic yoke assembly that rotates integrally with the other of the input shaft and the output shaft, and is configured to detect the steering torque applied to the shaft as the state quantity, and the fixed unit comprises a pair of magnetic collecting members arranged at intervals on the outer circumference of the magnetic yoke assembly, a circuit board on which a magnetic sensor that generates a signal corresponding to the magnetic flux flowing through the pair of magnetic collecting members is mounted, and a frame that holds the pair of magnetic collecting members and the circuit board, and the frame may be fixed to the main body.

[0009] With the above configuration, the frame that holds the magnetic collecting member and the circuit board is fixed to the main body, so the fixing unit can be easily fixed to the main body. In the above-described electric power steering device, the main body has a mounting hole that penetrates in the axial direction, and the frame has a seat that abuts against the main body from the axial direction and has a seat hole that penetrates in the axial direction, and the frame may be fixed to the main body by fastening the seat to the main body with rivets inserted through the mounting hole and the seat hole.

[0010] With the above configuration, the seat portion of the frame is fastened to the main body by rivets, so the frame can be firmly fixed to the main body. In the above-described electric power steering device, the main body has a mounting hole that penetrates in the axial direction, the frame has a seat that abuts against the partition member from the axial direction, and a fixing pin that is inserted into the mounting hole, and the frame may be fixed to the main body by heat crimping the tip of the fixing pin inserted into the mounting hole.

[0011] With the above configuration, the frame is fixed to the main body by heat-crimping the frame's fixing pins, which suppresses the increase in the number of parts compared to cases where fastening members such as rivets are used.

[0012] In the electric power steering device described above, the sensor device may further include a biasing member that biases the fixed unit toward the opposite side of the partition member. For example, dimensional tolerances of the components constituting the electric power steering system, or dimensional changes due to temperature fluctuations, can cause gaps in the fixing portion of the fixed unit to the partition member. As a result, the fixed unit may rattle, potentially reducing the accuracy of the state quantities detected by the sensor device. In this regard, the above configuration reduces rattle of the fixed unit because the fixed unit is biased toward the opposite side of the partition member by the biasing member. This suppresses a decrease in the accuracy of the state quantities detected by the sensor device.

[0013] In the electric power steering device described above, the sensor device may further include a biasing member that biases the fixed unit toward the partition member. With the above configuration, the fixed unit is biased toward the partition member by the biasing member, thus reducing rattle of the fixed unit. This suppresses a decrease in the accuracy of the state quantity detected by the sensor device. [Effects of the Invention]

[0014] According to the present invention, it is possible to suppress the complexity of the housing shape. [Brief explanation of the drawing]

[0015] [Figure 1] This is a schematic diagram of the electric power steering system of the first embodiment. [Figure 2] This is an enlarged cross-sectional view of the vicinity of the sensor device of the first embodiment. [Figure 3] This is an exploded perspective view of the sensor device and its peripheral components according to the first embodiment. [Figure 4] It is an enlarged cross-sectional view showing a fixed portion between a fixed unit and a partition member that constitute a sensor device of the first embodiment. [Figure 5] It is an enlarged cross-sectional view near a sensor device of the second embodiment. [Figure 6] It is a perspective view of a second support frame that constitutes a sensor device of the third embodiment. [Figure 7] It is an enlarged cross-sectional view showing a fixed portion between a fixed unit and a partition member that constitute a sensor device of the third embodiment.

Mode for Carrying Out the Invention

[0016] (First Embodiment) Hereinafter, a first embodiment of an electric power steering device will be described with reference to the drawings. (Overall Configuration) As shown in FIG. 1, an electric power steering device 1 includes a column shaft 3 that constitutes a steering shaft 2 and a steering column 4 that rotatably houses the column shaft 3. The column shaft 3 and the steering column 4 are arranged on a common axis L. The electric power steering device 1 also includes a sensor device 5 and an electric actuator 6. The steering column 4 is mounted on the vehicle so as to generally extend along the vehicle's longitudinal direction. In the following description, the left side in FIG. 1 is defined as the front side of the vehicle, and the right side in FIG. 1 is defined as the rear side of the vehicle. Also, directions represented by terms such as "front", "rear", "upper", "lower", "left", and "right" are defined based on the vehicle.

[0017] A steering wheel 7 is connected to the rear end of the column shaft 3. An intermediate shaft and a pinion shaft (both not shown) that constitute the steering shaft 2 are connected to the front end of the column shaft 3. The pinion shaft is connected to the steered wheels via a rack shaft. Thereby, the steered wheels are steered in response to the driver's steering operation.

[0018] The sensor device 5 outputs both a signal for detecting the steering torque input by the driver and a signal for detecting the steering angle, which is the rotation angle of the column shaft 3. The steering torque and the steering angle correspond to state quantities indicating the steering state. The electric actuator 6 includes a motor 8 and a speed reducer 9. The motor 8 is controlled by a control device (not shown) so as to generate a torque corresponding to a signal including the signal output from the sensor device 5. The rotation of the motor 8 is decelerated by the speed reducer 9 and transmitted to the column shaft 3. Thereby, the electric actuator 6 applies an assist force for assisting the steering operation by the driver. The speed reducer 9 of the present embodiment is a worm speed reducer having a worm shaft 9a and a worm wheel 9b, but is not limited thereto, and any other speed reducer may be used.

[0019] (Column shaft 3) The column shaft 3 includes an upper shaft 11 and a lower shaft 12. The upper shaft 11 has an elongated cylindrical shape. A steering wheel 7 is connected to the rear end portion of the upper shaft 11.

[0020] In this specification, the "cylindrical shape" only needs to be regarded as a cylindrical shape as a whole, and includes those formed by combining a plurality of parts into a cylindrical shape, and those having a notch or the like in part such as a C shape. The "cylindrical shape" includes, but is not limited to, a circular shape, an elliptical shape, and a polygon having sharp or rounded corners when viewed in the axial direction. In the present embodiment, the upper shaft 11 has a circular shape when viewed in the axial direction.

[0021] The lower shaft 12 includes an input shaft 13, an output shaft 14, and a torsion bar 15 that connects the input shaft 13 and the output shaft 14 to each other. The input shaft 13 has, for example, an elongated cylindrical shape. The input shaft 13 is fitted into the inner peripheral portion of the upper shaft 11 through spline engagement. Thereby, the input shaft 13 is connected to the upper shaft 11 so as to be rotatable integrally and axially movable with respect to the upper shaft 11. The input shaft 13 has a fixing hole 16 that opens at the front end portion.

[0022] The output shaft 14 is, for example, shaped like an elongated cylinder. In this embodiment, the output shaft 14 has a circular shape when viewed in the axial direction. The front end of the input shaft 13 is inserted into the rear end of the output shaft 14. A bearing 17 is provided between the outer circumferential surface of the front end of the input shaft 13 and the inner circumferential surface of the rear end of the output shaft 14. As a result, the output shaft 14 rotatably supports the input shaft 13. A worm wheel 9b is fixed to the outer circumference of the output shaft 14.

[0023] The torsion bar 15 is, for example, shaped like an elongated cylinder. The rear end of the torsion bar 15 is fitted into a fixing hole 16, thereby connecting it to the input shaft 13 so that it can rotate integrally with it. The front end of the torsion bar 15 is fitted onto the inner circumference of the front end of the output shaft 14, thereby connecting it to the output shaft 14 so that it can rotate integrally with it. As a result, the input shaft 13 and the output shaft 14 rotate relative to each other by twisting the torsion bar 15.

[0024] (Steering column 4) The steering column 4 comprises an outer tube 21, an inner tube 22, and a housing 23.

[0025] The outer tube 21 is cylindrical in shape. The outer tube 21 rotatably supports the upper shaft 11 via a bearing 24. The inner tube 22 is cylindrical in shape and is narrower than the outer tube 21. In this embodiment, the outer tube 21 and the inner tube 22 have a circular shape when viewed in the axial direction. The rear end of the inner tube 22 is fitted into the inner circumference of the outer tube 21. The front end of the inner tube 22 is fixed to the housing 23.

[0026] As shown in Figure 2, the housing 23 comprises a housing body 31, a cover 32, and a partition member 33. The housing body 31 is cylindrical. In this embodiment, the housing body 31 has a circular shape when viewed in the axial direction. The housing body 31 has an end wall at one end in the axial direction. In the illustrated example, the end wall is provided at the front end of the housing body 31. The end wall of the housing body 31 has a through hole 34 that penetrates in the axial direction. The peripheral wall of the housing body 31 has a notch 37 into which the connector 36 of the wire harness 35 connected to the sensor device 5 is fitted. The notch 37 is, for example, rectangular in shape. The notch 37 is also provided at, for example, the rear end of the peripheral wall of the housing body 31 and opens to the rear. The cover 32 is disc-shaped. The cover 32 is fixed to the rear end of the housing body 31 so as to cover the opening of the housing body 31. The cover 32 has a through hole 38 that penetrates in the axial direction.

[0027] The partition member 33 has, for example, a disc-shaped main body portion 41 perpendicular to the axial direction of the column shaft 3. The partition member 33 is fixed to the inner circumferential surface of the housing body 31, for example, by press-fitting. As a result, the partition member 33 divides the space inside the housing body 31 into a reduction gear housing space S1 located at the front and a sensor housing space S2 located at the rear. In other words, the reduction gear housing space S1 and the sensor housing space S2 are arranged side by side in the axial direction of the column shaft 3. To put it another way, the partition member 33 divides the internal space of the housing 23 in the axial direction so that the reduction gear housing space S1 and the sensor housing space S2 are arranged side by side in the axial direction of the column shaft 3. The reduction gear housing space S1 houses the reduction gear 9, and the sensor housing space S2 houses the sensor device 5. The reduction gear housing space S1 is filled with grease.

[0028] The main body portion 41 of the partition member 33 has a through hole 42 and mounting holes 43 that penetrate the column shaft 3 in the axial direction. The through hole 42 is located in the center of the main body portion 41. As a result, the through holes 34, 38, and 42 are all located on the axis L. The housing 23 of this embodiment rotatably supports the output shaft 14 via bearings 44 and 45 provided in the through holes 34 and 42. The mounting holes 43 are, for example, round holes. The partition member 33 of this embodiment has, for example, three mounting holes 43, but the number may be one or more and can be changed as appropriate. In addition, the mounting holes 43 are provided on the outer circumference side of the through hole 42, for example, at equal angular intervals in the circumferential direction, but their arrangement can be changed as appropriate.

[0029] (Sensor device 5) As shown in Figures 2 and 3, the sensor device 5 comprises a sensor magnet 51, a magnetic yoke assembly 52, a fixing unit 53, and a biasing member 54. Note that in Figure 3, for the sake of clarity, the rivet 91, which will be discussed later, is not shown.

[0030] (Sensor magnet 51) The sensor magnet 51 is a ring magnet that is cylindrical in shape when viewed axially. The sensor magnet 51 is magnetized radially such that magnetic poles of different polarities are alternately arranged in the circumferential direction. The sensor device 5 of this embodiment includes a magnet holder 55, and the sensor magnet 51 is fixed to the outer circumferential surface of the input shaft 13 via the magnet holder 55. In other embodiments, the sensor magnet 51 may be directly fixed to the outer circumferential surface of the input shaft 13. In yet another embodiment, the sensor magnet 51 may be a plurality of plate-shaped magnets.

[0031] (Magnetic yoke assembly 52) As shown in Figures 3 and 4, the magnetic yoke assembly 52 comprises a pair of yoke cores 61, 62, a collar 63, and a holder 64 that holds the pair of yoke cores 61, 62 and the collar 63.

[0032] Each of the yoke cores 61 and 62 is made of a magnetic material and is ring-shaped. The yoke cores 61 and 62 are spaced apart in the axial direction. Each of the yoke cores 61 and 62 has multiple claw portions. The claw portions protrude toward each other. The claw portions are provided at equal intervals in the circumferential direction, and the claw portions of yoke core 61 and yoke core 62 are arranged alternately in the circumferential direction.

[0033] In this specification, "annular" means that the whole can be considered an annular shape, and includes those formed by combining multiple parts to form an annular shape, as well as those having a notch in part, such as a C-shape. The shape of an "annular" includes, but is not limited to, circular, elliptical, and polygonal shapes with sharp or rounded corners when viewed in the axial direction. In this embodiment, each of the yoke cores 61 and 62 has a circular shape when viewed in the axial direction.

[0034] The collar 63 is made of, for example, a metal material and is annular in shape. In this embodiment, the collar 63 has a circular shape when viewed in the axial direction. The collar 63 is positioned axially in front of the pair of yoke cores 61 and 62. The collar 63 is fitted onto the outer circumference of the rear end of the output shaft 14.

[0035] The holder 64 is made of, for example, a resin material and is cylindrical in shape. In this embodiment, the holder 64 has a circular shape when viewed axially. The axial direction of the holder 64 coincides with the direction along the axis L. In this embodiment, the holder 64 is integrated with a pair of yoke cores 61, 62 and a collar 63 by insert molding. In other embodiments, the holder 64 may be molded separately, and then the yoke cores 61, 62 and the collar 63 may be assembled to the holder 64. The holder 64 holds the pair of yoke cores 61, 62 and the collar 63 on the axis L. Specifically, the holder 64 holds the yoke cores 61, 62 such that the inner surface of the claw portion is exposed on the inner circumference side of the holder 64, and holds the collar 63 such that the inner surface of the collar 63 is exposed on the inner circumference side of the holder 64.

[0036] Furthermore, the holder 64 has a gear portion 65. The gear portion 65 is provided at the front end of the outer circumferential surface of the holder 64. The gear portion 65 has a plurality of external teeth that protrude radially outward from the holder 64.

[0037] The magnetic yoke assembly 52 is fixed to the output shaft 14 so as to be able to rotate integrally with it by press-fitting the collar 63 onto the rear end of the output shaft 14. With the magnetic yoke assembly 52 fixed to the output shaft 14, the magnetic yoke assembly 52 is positioned at a distance from the outer circumference of the sensor magnet 51.

[0038] (Fixed unit 53) As shown in Figure 3, the stationary unit 53 comprises a pair of magnetic collecting members 71, 72, a circuit board 73, a gear subunit 74, and a frame 75. The gear subunit 74 includes two driven gears 76, 77 that rotate in accordance with the rotation of the magnetic yoke assembly 52. ​​The circuit board 73 includes a magnetic sensor 78 that generates a signal corresponding to the magnetic flux flowing through the pair of magnetic collecting members 71, 72, and rotation sensors 79a, 79b that generate signals corresponding to the rotation angles of the driven gears 76, 77. The signal output from the magnetic sensor 78 corresponds to the steering torque, and the signals output from the rotation sensors 79a, 79b correspond to the steering angle.

[0039] The fixed unit 53 may also output the signal itself from the magnetic sensor 78 and / or the signals itself from the rotation sensors 79a and 79b to the control device of the motor 8. Alternatively, the sensor device 5 may output the steering torque detected based on the signal from the magnetic sensor 78 and / or the steering angle detected based on the signals from the rotation sensors 79a and 79b to the control device of the motor 8.

[0040] (Frame 75) The frame 75 comprises a first support frame 81 and a second support frame 82. The first support frame 81 has an annular first frame portion 83 and a cover portion 84. The first frame portion 83 holds the magnetic collecting member 71 such that the inner circumferential surface of the magnetic collecting member 71 is exposed on the inner circumferential side of the first support frame 81. The cover portion 84 is provided on the radially outer side of the first frame portion 83. The cover portion 84 has a shape corresponding to the support portion 86 and connector portion 87 of the second support frame 82, which will be described later. The first support frame 81 is fixed to the second support frame 82 such that the cover portion 84 covers the support portion 86 and connector portion 87.

[0041] The second support frame 82 has an annular second frame portion 85, a support portion 86, a connector portion 87, and a seat portion 88. The second frame portion 85 holds the magnetic collecting member 72 such that the inner circumferential surface of the magnetic collecting member 72 is exposed on the inner circumferential side of the second support frame 82. The support portion 86 is provided radially outward of the second frame portion 85. The support portion 86 supports the gear subunit 74 and the circuit board 73. The connector portion 87 is provided radially outward of the second frame portion 85 so as to be aligned circumferentially with the support portion 86. The connector portion 87 is configured to allow connection of the connector 36 of the wire harness 35.

[0042] As shown in Figures 3 and 4, the second support frame 82 of this embodiment has, for example, three seat portions 88, but the number may be one or more, and can be changed as appropriate. The seat portions 88 are provided in a position that protrudes forward from the radially outer portion of the second frame portion 85 compared to other parts of the second support frame 82. The seat portions 88 are also provided, for example, at equal angular intervals in the circumferential direction, but their arrangement can be changed as appropriate. The seat portions 88 have a flat plate shape perpendicular to the axial direction and abut against the main body portion 41 of the partition member 33 from the rear. The seat portions 88 are provided with seat holes 89 that penetrate in the axial direction.

[0043] The second support frame 82 is positioned such that its seat hole 89 faces the mounting hole 43 of the partition member 33. The second support frame 82 is fixed to the partition member 33 by fastening its seat 88 to the main body 41 of the partition member 33 with rivets 91 inserted into the mounting hole 43 and the seat hole 89.

[0044] Specifically, as shown in Figure 4, the rivet 91 has a shaft portion 92 inserted into the mounting hole 43 and the seat hole 89, a first head portion 93 provided at the rear end of the shaft portion 92, and a second head portion 94 provided at the front end of the shaft portion 92. The outer diameters of both the first head portion 93 and the second head portion 94 are larger than the inner diameters of the mounting hole 43 and the seat hole 89. The rivet 91 fastens the seat portion 88 to the main body portion 41 by sandwiching the seat portion 88 and the main body portion 41 between the first head portion 93 and the second head portion 94. In this embodiment, for example, a blind rivet is used for the rivet 91.

[0045] (Magnetic collecting members 71, 72) As shown in Figures 3 and 4, each of the magnetic collecting members 71 and 72 is made of a magnetic material and is C-shaped. The magnetic collecting member 71 has two radially projecting protrusions 101, and the magnetic collecting member 72 has two radially projecting protrusions 102. The magnetic collecting member 71 is held by the first frame portion 83 of the first support frame 81 and is positioned at a distance from the outer circumference of the yoke core 61. The magnetic collecting member 72 is held by the second frame portion 85 of the second support frame 82 and is positioned at a distance from the outer circumference of the yoke core 62. In other words, the magnetic collecting members 71 and 72 are positioned at a distance from each other in the axial direction. Magnetic flux flowing through the yoke core 61 is induced in the magnetic collecting member 71, and magnetic flux flowing through the yoke core 62 is induced in the magnetic collecting member 72. The protrusions 101 and 102 face each other in the axial direction.

[0046] In this specification, "facing" means that two surfaces or members are facing each other, and includes not only cases where they are completely facing each other, but also cases where they are partially facing each other. Furthermore, in this specification, "facing" includes both cases where another member is interposed between the two parts, and cases where nothing is interposed between the two parts.

[0047] (Gear sub-unit 74) As shown in Figure 3, the gear subunit 74 includes, in addition to the driven gears 76 and 77, sensor magnets 111 and 112 that rotate integrally with the driven gears 76 and 77, and a support plate 113. Sensor magnet 111 is fixed so as to be able to rotate integrally with the driven gear 76. Sensor magnet 112 is fixed so as to be able to rotate integrally with the driven gear 77. Each of the driven gears 76 and 77 meshes with the gear section 65 of the magnetic yoke assembly 52. ​​The number of teeth of the driven gears 76 and 77 are different. Therefore, when the output shaft 14, i.e., the gear section 65, rotates, the rotation angles of the driven gear 76 and the driven gear 77 are different.

[0048] The support plate 113 is flat. The support plate 113 rotatably supports the driven gears 76 and 77. The support plate 113 is fixed to the second support frame 82 such that the driven gears 76 and 77 are sandwiched between the support plate 113 and the support portion 86 of the second support frame 82.

[0049] (Circuit board 73) The circuit board 73 is flat and, in an axial view, has a contour corresponding to the shape of the support portion 86 and connector portion 87 of the second support frame 82. Various circuit elements, including the magnetic sensor 78 and rotation sensors 79a and 79b, are mounted on the circuit board 73. The circuit board 73 is supported by the support portion 86 of the second support frame 82. The circuit board 73 is covered from the rear by the cover portion 84 of the first support frame 81.

[0050] The magnetic sensor 78 is, for example, a Hall sensor or a magnetoresistive sensor. As shown in Figure 2, the magnetic sensor 78 is mounted in the region between the protrusions 101 and 102 on the circuit board 73. In other embodiments, the circuit board may include a redundant magnetic sensor separate from the magnetic sensor 78, which may be mounted in the region between the other protrusions 101 and 102 on the circuit board 73.

[0051] Here, the sensor magnet 51 rotates integrally with the input shaft 13, and the magnetic yoke assembly 52 rotates integrally with the output shaft 14. When the driver operates the steering wheel, the input shaft 13 and the output shaft 14 rotate relative to each other, accompanied by the twisting of the torsion bar 15, and the relative circumferential position of the sensor magnet 51 and the magnetic yoke assembly 52 changes. As a result, the magnetic flux flowing through the yoke cores 61 and 62 changes in accordance with the amount of twisting of the torsion bar 15, i.e., the magnitude of the steering torque input by the driver. Consequently, the magnetic flux flowing through the magnetic collecting members 71 and 72 also changes in accordance with the change in the magnetic flux flowing through the yoke cores 61 and 62. The magnetic sensor 78 detects the magnetic flux flowing through the magnetic collecting members 71 and 72 and generates a signal corresponding to this magnetic flux, i.e., a signal indicating the steering torque.

[0052] The rotation sensors 79a and 79b are, for example, Hall sensors or magnetoresistive sensors. Rotation sensor 79a is mounted in the region of the circuit board 73 facing the sensor magnet 111, and rotation sensor 79b is mounted in the region of the circuit board 73 facing the sensor magnet 112.

[0053] Here, the driven gears 76 and 77 rotate in accordance with the rotation of the magnetic yoke assembly 52. ​​The rotation sensors 79a and 79b then generate signals indicating the rotation angle of the driven gears 76 and 77, i.e., the steering angle. As described above, the rotation angles of the driven gear 76 and the driven gear 77 are different from each other, so the phases of the signals generated by the rotation sensors 79a and 79b are different. Therefore, the sensor device 5 of this embodiment can detect the steering angle in absolute angles exceeding 360° based on the signals output from the rotation sensors 79a and 79b.

[0054] (Biasing member 54) As shown in Figures 2 and 3, the biasing member 54 is a rectangular leaf spring. The base end of the biasing member 54 is positioned within the notch 37 of the housing body 31. The base end of the biasing member 54 is fixed by being sandwiched between the inner surface of the notch 37 and the connector 36 of the wire harness 35. The tip of the biasing member 54 biases a part of the second support frame 82, for example, the connector portion 87, from its front to its rear. In other words, the biasing member 54 biases the fixing unit 53 toward the opposite side of the partition member 33.

[0055] Next, the operation and effects of this embodiment will be described. (1-1) The housing 23 includes a partition member 33 having a plate-shaped main body portion 41 perpendicular to the axial direction of the column shaft 3. The partition member 33 divides the internal space of the housing 23 into a gearbox housing space S1 and a sensor housing space S2. The gearbox housing space S1 and the sensor housing space S2 are arranged side by side in the axial direction. The fixing unit 53 of the sensor device 5 is fixed to the main body portion 41 in the axial direction.

[0056] According to the above configuration, since the partition member 33 has a main body portion 41 perpendicular to the axial direction, the fixing unit 53 can be fixed to the partition member 33 in the axial direction without having to separately provide mounting walls or the like on the partition member 33 to support the fixing unit 53. This makes it possible to suppress the complexity of the shape of the partition member 33, and consequently the shape of the housing 23.

[0057] (1-2) The fixed unit 53 includes a frame 75 that holds a pair of magnetic collecting members 71 and 72 and a circuit board 73, and a second support frame 82 of the frame 75 is fixed to the main body 41. Therefore, the fixed unit 53 can be easily fixed to the main body 41.

[0058] (1-3) The main body portion 41 has mounting holes 43 that penetrate in the axial direction. The second support frame 82 has a seat portion 88 that abuts against the main body portion 41 from the axial direction. The seat portion 88 has a seat portion hole 89 that penetrates in the axial direction. The second support frame 82 is fixed to the main body portion 41 by fastening the seat portion 88 to the main body portion 41 with rivets 91 that are inserted through the mounting holes 43 and the seat portion hole 89. As a result, the frame 75 can be firmly fixed to the main body portion 41 of the partition member 33.

[0059] (1-4) The sensor device 5 further includes a biasing member 54 that biases the fixed unit 53 toward the opposite side of the partition member 33. For example, due to dimensional tolerances of the components constituting the electric power steering device 1 or dimensional changes due to temperature changes, gaps may occur in the fixing portion of the fixing unit 53 to the partition member 33. Specifically, for example, gaps may occur between the seat portion 88, the main body portion 41, and the first head portion 93 and the second head portion 94 of the rivet 91. As a result, the fixing unit 53 may rattle, which may reduce the accuracy of the steering torque and steering angle detected by the sensor device 5. In this regard, with the above configuration, since the fixing unit 53 is biased toward the opposite side of the partition member 33 by the biasing member 54, the seat portion 88 pulls the first head portion 93 of the rivet 91 toward the rear, causing the second head portion 94 to be pressed against the front side surface of the partition member 33. This reduces rattle of the fixing unit 53 and suppresses a decrease in the accuracy of the steering torque and steering angle detected by the sensor device 5.

[0060] (1-5) The biasing member 54 is positioned within the notch 37 of the housing body 31 and is fixed by being sandwiched between the inner surface of the notch 37 and the connector 36 of the wire harness 35. Therefore, there is no need to separately provide a part in the housing 23 for positioning the biasing member 54, and the complexity of the shape of the housing 23 can be suppressed.

[0061] (Second Embodiment) Next, a second embodiment of the electric power steering system will be described with reference to the drawings. For the sake of clarity, identical components will be denoted by the same reference numerals as in the first embodiment, and their descriptions will be omitted.

[0062] As shown in Figure 5, the biasing member 121 in this embodiment is a rectangular leaf spring. The base end of the biasing member 121 is positioned within the notch 37 of the housing body 31. The base end of the biasing member 121 is fixed within the notch 37 by being sandwiched between the cover 32 and the connector 36 of the wire harness 35. The tip of the biasing member 121 biases a part of the first support frame 81, for example, the cover portion 84, from the rear to the front. In other words, the biasing member 121 biases the fixing unit 53 toward the partition member 33.

[0063] In this embodiment, in addition to the same effects and effects as those described in (1-1) to (1-3) of the first embodiment above, the following effects and effects are also achieved. (2-1) The sensor device 5 further includes a biasing member 121 that biases the fixed unit 53 toward the partition member 33. As a result, the seat portion 88 is pressed against the rear side surface of the partition member 33. This reduces rattling of the fixed unit 53 and suppresses a decrease in the accuracy of the steering torque and steering angle detected by the sensor device 5.

[0064] (2-2) The biasing member 121 is positioned within the notch 37 of the housing body 31 and is fixed by being sandwiched between the cover 32 and the connector 36 of the wire harness 35. Therefore, there is no need to separately provide a part in the housing 23 for positioning the biasing member 121, and the complexity of the housing 23's shape can be suppressed.

[0065] (Third embodiment) Next, a third embodiment of the electric power steering system will be described with reference to the drawings. For the sake of explanation, identical components will be denoted by the same reference numerals as in the first embodiment, and their descriptions will be omitted.

[0066] As shown in Figure 6, the second support frame 82 of this embodiment has a plurality of fixing pins 131. The second support frame 82 has, for example, three fixing pins 131, but the number may be one or more, and can be changed as appropriate.

[0067] The fixing pin 131 protrudes forward from the radially outer portion of the second frame portion 85. As shown in Figure 6, before being fixed to the partition member 33, the fixing pin 131 protrudes forward from the seat portion 88, that is, from other parts of the second support frame 82. In this embodiment, the seat portion 88 does not have a seat hole 89, but it may have a seat hole 89 as in the first embodiment described above.

[0068] As shown in Figure 7, the fixing pin 131 is inserted into the mounting hole 43 of the partition member 33. The second support frame 82 is fixed to the partition member 33 by heat crimping (welding) the tip 132 of the fixing pin 131 inserted into the mounting hole 43. Specifically, the tip 132 of the fixing pin 131 is formed into a disc shape with an outer diameter larger than the inner diameter of the mounting hole 43 by heat crimping. As a result, the second support frame 82 is fixed to the main body 41 of the partition member 33 by sandwiching the main body 41 of the partition member 33 between the tip 132 of the fixing pin 131 and the seat portion 88.

[0069] In this embodiment, in addition to the same actions and effects as those described in (1-1), (1-2), (1-4), and (1-5) of the first embodiment, the following actions and effects are also achieved. (3-1) The partition member 33 has a mounting hole 43 that penetrates in the axial direction, and the frame 75 has a seat portion 88 that abuts the partition member 33 from the axial direction and a fixing pin 131 that is inserted into the mounting hole 43. The frame 75 is fixed to the main body portion 41 of the partition member 33 by heat crimping the tip portion 132 of the fixing pin 131 inserted into the mounting hole 43. Therefore, the increase in the number of parts can be suppressed compared to the case in which fastening members such as rivets are used.

[0070] Each of the above embodiments can be implemented with the following modifications. Each of the above embodiments and the following modifications can be combined with each other to the extent that they do not contradict each other technically. In each of the above embodiments, a bearing 45 is provided in the through hole 42 of the partition member 33, but this is not limited to this. For example, a bearing may be provided in the through hole 38 of the cover 32 to rotatably support the input shaft 13, and the way in which the housing 23 supports the column shaft 3 can be changed as appropriate. In other words, the partition member 33 does not have to be a member that supports the column shaft 3 via a bearing. Also, the partition member 33 only needs to be a member that has a portion that intersects the axial direction so as to divide the internal space of the housing 23 in the axial direction of the steering shaft 2, and the shape of the partition member 33 can be changed as appropriate. For example, in each of the above embodiments, the main body portion 41 of the partition member 33 may be oblique to the axial direction of the column shaft 3.

[0071] In the embodiments described above, leaf springs were used as the biasing members 54 and 121, but the invention is not limited to these, and other types of springs, such as disc springs or coil springs, may also be used. Furthermore, the position where the biasing members 54 and 121 are provided is not limited to the notch 37 of the housing body 31, but can be provided at any position as long as it can bias the frame 75. In this case, it is preferable to provide the biasing members near the fixing portion between the fixing unit 53 and the partition member 33, for example, the seat portion 88.

[0072] In the third embodiment described above, instead of the biasing member 54, the fixing unit 53 may be biased toward the partition member 33 by the biasing member 121. Also, in each of the above embodiments, the fixing unit 53 may be configured not to be biased. In other words, the fixing unit 53 may be configured not to include the biasing members 54 and 121.

[0073] In each of the above embodiments, the manner in which the second support frame 82 is fixed to the partition member 33 can be changed as appropriate. For example, in the first and second embodiments, in addition to the rivets 91, the second support frame 82 may be fixed to the partition member 33 by heat-crimping a fixing pin, as in the third embodiment. Alternatively, in addition to or instead of the rivets 91 and heat-crimping, the second support frame 82 may be fixed to the partition member 33 by, for example, bolts. Furthermore, in addition to or instead of the rivets 91 and heat-crimping, the second support frame 82 may be fixed to the partition member 33 by a snap-fit ​​structure in which an elastically deformable locking pin is provided on the second support frame 82 and the locking pin is engaged with the mounting hole 43 of the partition member 33.

[0074] In the embodiments described above, the frame 75 is composed of a first support frame 81 and a second support frame 82, but it is not limited to this, and for example, the frame 75 may be composed of a single member.

[0075] In each of the above embodiments, the rotation sensors 79a and 79b may be sensors other than those that detect magnetic flux, such as rotary encoders, as long as they can detect the rotation angle of the driven gears 76 and 77. In this case, the sensor magnets 111 and 112 are not required.

[0076] The gear subunit 74 is equipped with two driven gears 76 and 77 that mesh with the gear section 65, but it is not limited to this, and may be equipped with only a single driven gear that meshes with the gear section 65, or with three or more driven gears. Furthermore, if the gear subunit 74 is equipped with two or more driven gears, each of these driven gears does not have to mesh with the gear section 65; for example, one driven gear may mesh with the gear section 65, and the other driven gears may mesh with only that one driven gear.

[0077] In each of the above embodiments, the sensor device 5 is configured to detect both steering torque and steering angle, but it is not limited to this, and may be configured to detect only one of steering torque or steering angle. If the sensor device 5 detects only steering torque, the components for detecting steering angle, such as the gear subunit 74 and the gear portion 65 of the magnetic yoke assembly 52, may be omitted. Also, if the sensor device 5 detects only steering angle, the components for detecting steering torque, such as the magnetic collecting members 71, 72 and the yoke cores 61, 62, may be omitted. Furthermore, the sensor device 5 may detect state quantities indicating steering conditions other than steering torque and steering angle, such as steering speed.

[0078] Although the sensor magnet 51 is fixed to the input shaft 13 and the magnetic yoke assembly 52 is fixed to the output shaft 14, the sensor magnet 51 may be fixed to the output shaft 14 and the magnetic yoke assembly 52 may be fixed to the input shaft 13.

[0079] The sensor device 5 is installed on the outer circumference of the column shaft 3, but it is not limited to this location; for example, it may be installed on the outer circumference of the pinion shaft. In this case, the electric actuator 6 will provide an assist force to the pinion shaft. [Explanation of Symbols]

[0080] 1: Electric power steering system 3: Column shaft (shaft) 5: Sensor device 6: Electric Actuator 8: Reducer 23: Housing 33: Partition Member 41: Main body 53: Fixed Unit S1: Gear reducer housing space S2: Sensor housing space

Claims

1. A shaft that rotates according to the driver's operation, An electric actuator that applies assisting force to the aforementioned shaft, A sensor device that detects a state quantity indicating the steering state, An electric power steering device comprising the shaft, the electric actuator, and a housing that accommodates the sensor device, The electric actuator includes a motor and a reduction gear that reduces the rotation of the motor and transmits it to the shaft. The sensor device includes a fixing unit that is fixed to the housing, The housing comprises a housing member that partitions the internal space of the housing, and a partition member fitted inside the housing member, the partition member having a plate-shaped main body that intersects the axial direction of the shaft. The partition member further divides the internal space of the housing into a reduction gear housing space in which the reduction gear is housed and a sensor housing space in which the sensor device is housed. The reduction gear housing space and the sensor housing space are arranged side by side in the axial direction. The aforementioned fixing unit is an electric power steering device fixed to the main body in the axial direction.

2. An electric power steering device according to claim 1, The shaft includes an input shaft and an output shaft connected to the input shaft via a torsion bar. The sensor device further includes a sensor magnet that rotates integrally with either the input shaft or the output shaft, and a magnetic yoke assembly that rotates integrally with the other of the input shaft and the output shaft, and is configured to detect the steering torque applied to the shaft as the state quantity. The fixed unit comprises a pair of magnetic collecting members arranged at intervals on the outer circumference of the magnetic yoke assembly, a circuit board on which a magnetic sensor that generates a signal corresponding to the magnetic flux flowing through the pair of magnetic collecting members is mounted, and a frame that holds the pair of magnetic collecting members and the circuit board. The main body is equipped with an electric power steering device to which the frame is fixed.

3. The electric power steering device according to claim 2, The main body portion has a mounting hole that penetrates in the axial direction, The frame has a seat portion that abuts the main body portion from the axial direction, and the seat portion has a seat portion hole that penetrates in the axial direction. The frame is an electric power steering device fixed to the main body by fastening the seat portion to the main body with rivets inserted through the mounting holes and the seat portion holes.

4. The electric power steering device according to claim 2, The main body portion has a mounting hole that penetrates in the axial direction, The frame has a seat portion that abuts the partition member from the axial direction and a fixing pin that is inserted into the mounting hole. The frame is an electric power steering device that is fixed to the main body by heat crimping the tip of the fixing pin inserted into the mounting hole.

5. An electric power steering device according to any one of claims 1 to 4, The sensor device further comprises an electric power steering device which biases the fixed unit toward the opposite side of the partition member.

6. An electric power steering device according to any one of claims 1 to 4, The sensor device further comprises a biasing member that biases the fixed unit toward the partition member, and is an electric power steering device.

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