Electric power steering device

Abstract

An electric power steering device (100) comprises: a housing (60) that has a first cylindrical part (61) and accommodates a torque sensor (40); a through-hole (61a) that is formed so as to penetrate the first cylindrical part (61) of the housing (60); and a cable (36) that is inserted into the through-hole (61a) and is electrically connected to the torque sensor (40). The housing (60) has a plate (70) that closes an opening of the first cylindrical part (61). The torque sensor (40) has a connector (49) to which the cable (36) is connected. The through-hole (61a) is formed so as to extend in a slanted direction relative to a direction toward the center of the first cylindrical part (61). The plate (70) has a cable protection part (72) that can come into contact with the cable (36) and prevents the cable (36) from coming into contact with an opening part (61b) of the through-hole (61a).

Description

Electric power steering device

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

[0002] JP2018-43731A discloses an electric power steering device including an input shaft to which steering torque is input, an output shaft connected to the input shaft via a torsion bar, a torque sensor attached across the input shaft and the output shaft and detecting steering torque, a housing accommodating the input shaft, the output shaft, and the torque sensor, an electric motor that generates steering assist torque based on the detection result of the torque sensor, and a cable electrically connecting the torque sensor and a controller that controls the drive of the electric motor. The torque sensor has a connector to which the cable is connected. An insertion hole is formed in an annular side wall of the housing, and the cable is drawn from the outside of the housing into the inside of the housing through the insertion hole and connected to the connector.

[0003] In the electric power steering device described in JP2018-43731A, if the cable comes into contact with the opening of the insertion hole during assembly or while the vehicle is running, the cable may be damaged. In particular, if the insertion hole is formed to extend in a direction inclined with respect to the direction toward the center of the annular side wall portion, the opening of the insertion hole becomes sharp, making it easy for the cable to come into contact with the opening of the insertion hole and be damaged.

[0004] An object of the present invention is to prevent damage to a cable electrically connected to a torque sensor in an electric power steering device.

[0005] According to one aspect of the present invention, there is provided an electric power steering device comprising: an input shaft to which steering torque is input; an output shaft connected to the input shaft via a torsion bar; a torque sensor attached across the input shaft and the output shaft and detecting the steering torque; a housing having a cylindrical portion and accommodating the torque sensor; an electric motor that generates steering assist torque based on the detection result of the torque sensor; a through hole formed through the cylindrical portion of the housing; and a cable inserted into the through hole and electrically connected to the torque sensor, wherein the housing has a plate that covers the opening of the cylindrical portion, the torque sensor has a connector to which the cable is connected, the through hole is formed to extend in a direction inclined with respect to the direction toward the center of the cylindrical portion, and the plate has a cable protection portion that is contactable with the cable and prevents the cable from contacting the opening of the through hole.

[0006] FIG. 1 is a configuration diagram of an electric power steering device according to an embodiment of the present invention. FIG. 2 is an external view of the vicinity of an assist mechanism in an electric power steering device according to an embodiment of the present invention. FIG. 3 is a cross-sectional view of the vicinity of the assist mechanism in an electric power steering device according to an embodiment of the present invention. FIG. 4 is a plan view of the vicinity of the assist mechanism in an electric power steering device according to an embodiment of the present invention, with the first housing omitted. FIG. 5 is a perspective view of the vicinity of the assist mechanism in an electric power steering device according to an embodiment of the present invention, with the first housing omitted. FIG. 6 is a perspective view of a plate. FIG. 7 is a perspective view of a plate according to a modified embodiment of the present invention.

[0007] An electric power steering device 100 according to an embodiment of the present invention will be described below with reference to the drawings.

[0008] The electric power steering device 100 is mounted on a vehicle and assists the driver in steering the steering wheel 1 .

[0009] As shown in FIG. 1, the electric power steering device 100 includes a steering mechanism 10 that steers the wheels 2 in response to the rotation of the steering wheel 1 caused by steering by the driver, an assist mechanism 20 that assists the driver in steering, a torque sensor 40 that detects the steering torque input by the driver through the steering wheel 1, and a controller 30 that controls the drive of the electric motor 21 based on the detection result of the torque sensor 40.

[0010] The steering mechanism 10 has a steering shaft 11 that rotates in response to the rotation of the steering wheel 1 , and a rack shaft 12 that steers the wheels 2 in response to the rotation of the steering shaft 11 .

[0011] The steering shaft 11 has an input shaft 13 that rotates when the driver steers the steering wheel 1 and receives steering torque, an output shaft 15 that connects to a rack shaft 12 that steers the wheels 2, and a torsion bar 14 that connects the input shaft 13 and the output shaft 15. The output shaft 15 is connected to the input shaft 13 via the torsion bar 14.

[0012] A pinion 16 that meshes with a rack 12a formed on the rack shaft 12 is formed on the lower part of the output shaft 15. When the steering wheel 1 is steered, the steering shaft 11 rotates, and the rotation is converted into linear motion of the rack shaft 12 by the pinion 16 and the rack 12a, and the wheels 2 are steered via the knuckle arms 4.

[0013] The assist mechanism 20 has an electric motor 21 that generates steering assist torque, an output shaft 22 to which the driving force of the electric motor 21 is transmitted, and a speed reduction mechanism 3 that reduces the rotation of the electric motor 21 and transmits it to the output shaft 15. The speed reduction mechanism 3 has a worm shaft 3a connected to the output shaft 22 of the electric motor 21, and a worm wheel 3b that meshes with the worm shaft 3a and is fixed to the output shaft 15. The output of the electric motor 21 is reduced in speed by the speed reduction mechanism 3 and then transmitted as steering assist torque to the rack shaft 12 via the output shaft 15.

[0014] The torque sensor 40 is attached across the input shaft 13 and the output shaft 15, and detects the steering torque applied to the torsion bar 14 based on the difference in rotation angle between the input shaft 13 and the output shaft 15. A circuit board 47 (see FIG. 3 ) of the torque sensor 40 and the controller 30 are electrically connected via a cable 36 serving as a signal line. Power is supplied from the controller 30 to the torque sensor 40 via the cable 36, and a steering torque signal detected by the torque sensor 40 is output to the controller 30.

[0015] Next, the structure of the assist mechanism 20 in the electric power steering device 100 will be described in detail with reference to FIGS.

[0016] 2 and 3 , the assist mechanism 20 includes an electric motor 21, a housing 60, a cover 50, an input shaft 13, a torsion bar 14 (see FIG. 3 ), an output shaft 15, and a torque sensor 40 (see FIG. 3 ). A portion of the input shaft 13, a portion of the output shaft 15, and the torque sensor 40 are housed in the housing 60.

[0017] 2 and 3 , the cover 50 is provided to cover the opening of the housing 60 (specifically, the opening of the first cylindrical portion 61, which will be described later). The cover 50 accommodates a seal member 91 that comes into sliding contact with the outer circumferential surface of the input shaft 13, and a bearing 92 that rotatably supports the input shaft 13. The seal member 91 prevents foreign matter from entering the cover 50. The cover 50 and the housing 60 are connected by bolts 18.

[0018] 2 to 5, the housing 60 has a first cylindrical portion 61, a second cylindrical portion 62 (see FIGS. 2 and 3) having an inner diameter smaller than that of the first cylindrical portion 61, an attachment portion 63 formed at the open end of the first cylindrical portion 61 and into which a bolt 18 is inserted for fastening the cover 50 and the housing 60, and a plate 70 attached to the housing 60. In this embodiment, the first cylindrical portion 61 corresponds to the "cylindrical portion" in the claims.

[0019] As shown in FIG. 2 , the electric motor 21 is attached to the outer wall surface of the first cylindrical portion 61. As shown in FIG. 3 , the first cylindrical portion 61 is formed in a cylindrical shape centered on the input shaft 13, and accommodates the torque sensor 40 and the worm wheel 3b inside. The worm shaft 3a connected to the output shaft 22 of the electric motor 21 is disposed to pass through the first cylindrical portion 61 and meshes with the worm wheel 3b housed inside the first cylindrical portion 61. As shown in FIGS. 3 and 5 , a plate 70 is attached inside the first cylindrical portion 61 and closes the opening of the first cylindrical portion 61. The disk-shaped plate 70 divides the interior of the first cylindrical portion 61 into a space where the torque sensor 40 is provided and a space where the worm wheel 3b is provided.

[0020] 4 and 5, the first cylindrical portion 61 has a through-hole 61a formed through the first cylindrical portion 61. The cable 36 is inserted through the through-hole 61a.

[0021] 3, a bearing 93 that rotatably supports the output shaft 15 and a seal member 94 that comes into sliding contact with the outer circumferential surface of the output shaft 15 are provided inside the second cylindrical portion 62. The seal member 94 prevents foreign matter from entering the housing 60.

[0022] As shown in FIG. 3 , a hollow portion opening to the lower end face is formed at the axial center of the input shaft 13, and a torsion bar 14 is housed within the hollow portion. The lower end of the torsion bar 14 protrudes from the lower end opening of the hollow portion of the input shaft 13 and is connected to the output shaft 15 via serrations 14 a. The torsion bar 14 transmits steering torque input to the input shaft 13 via the steering wheel 1 to the output shaft 15 and undergoes torsional deformation about its axis in response to the steering torque. In this manner, the input shaft 13 and the output shaft 15 rotate relative to each other in response to the amount of torsion of the torsion bar 14, and the torque sensor 40 detects the steering torque based on the difference in rotational angle between the input shaft 13 and the output shaft 15 due to this relative rotation. The electric motor 21 generates steering assist torque based on the detection result of the torque sensor 40.

[0023] Next, the specific structure of the torque sensor 40 will be described with reference to FIGS.

[0024] As shown in Figures 3 to 5, the torque sensor 40 has a case 41, a first sensor rotor 45 (see Figure 3) as a rotor part that rotates integrally with the input shaft 13, a second sensor rotor 46 (see Figure 3) that rotates integrally with the output shaft 15, a board 47 (see Figure 3) that detects steering torque and outputs a signal thereof to the controller 30, and a connector 49 to which the cable 36 is connected.

[0025] The case 41 is made of a resin material and has a generally annular shape, through which the input shaft 13 is inserted, and is provided so as to be rotatable relative to the input shaft 13, as shown in FIGS.

[0026] 4 and 5 , the case 41 has a cylindrical first cylindrical portion 41a, a cylindrical second cylindrical portion 41b having a larger diameter than the first cylindrical portion 41a, a bulging portion 41d formed to bulge radially outward from the outer circumferential surface of the first cylindrical portion 41a, and an engaging portion 48 formed to protrude further radially from the outer surface of the bulging portion 41d. As will be described later, the engaging portion 48 engages with a rotation stopper portion 73 of the plate 70, thereby restricting relative rotation of the torque sensor 40 (case 41) with respect to the housing 60.

[0027] 3 , the first sensor rotor 45 is attached to the outer peripheral surface of the input shaft 13, and the second sensor rotor 46 is attached to the outer peripheral surface of the output shaft 15. In the torque sensor 40 of this embodiment, the case 41 is supported by the input shaft 13 via the first sensor rotor 45 so as to be rotatable relative to the input shaft 13, and is supported by the output shaft 15 via the second sensor rotor 46 so as not to be rotatable relative to the output shaft 15. As a result, the first sensor rotor 45 rotates relative to the substrate 47 of the torque sensor 40 as the input shaft 13 rotates.

[0028] The substrate 47 of the torque sensor 40 is fixed inside the case 41 and disposed between the first sensor rotor 45 and the second sensor rotor 46. The torque sensor 40 detects the steering torque by detecting a change in the magnetic field caused by the difference in rotation angle between the input shaft 13 and the output shaft 15, i.e., the difference in rotation angle between the first sensor rotor 45 and the second sensor rotor 46, using a detection coil pattern formed on the substrate 47.

[0029] 3 to 5, the connector 49 is held on the upper surface of the second cylindrical portion 41b of the case 41. The cable 36 is inserted into a mounting opening 49a of the connector 49.

[0030] One end of the cable 36 is connected to the connector 49 of the torque sensor 40. The cable 36 is drawn out of the housing 60 through a through-hole 61 a formed in the first cylindrical portion 61 and the cable holder 31 that holds the cable 36. The other end of the cable 36 is connected to the controller 30.

[0031] Next, the plate 70 will be described in more detail with reference to FIGS.

[0032] As shown in Figures 4 to 6, the plate 70 has a circular main body portion 71, a cable protection portion 72 that can come into contact with the cable 36 and protects the cable 36, and a rotation stop portion 73 that restricts rotation of the case 41 of the torque sensor 40.

[0033] An outer peripheral edge 71b of the main body 71 protrudes in the axial direction and contacts the inner peripheral surface of the first cylindrical portion 61. A mounting recess 71c to which the cable protector 72 is attached is formed in the outer peripheral edge 71b. The input shaft 13 and the case 41 of the torque sensor 40 are inserted into the hollow portion 71a of the main body 71. The first cylindrical portion 41a, the second cylindrical portion 41b, the bulge portion 41d, and the engaging portion 48 of the case 41 of the torque sensor 40 are located above the main body 71.

[0034] The cable protector 72 is formed in an inverted U-shape, formed separately from the plate 70, and mounted in a mounting recess 71c on the outer circumferential edge 71b of the main body 71. The cable protector 72 faces the through-hole 61a of the first cylindrical portion 61 (see FIGS. 4 and 5). The cable protector 72 has an insertion hole 72a that corresponds to the opening 61b of the through-hole 61a and through which the cable 36 is inserted. Here, the "opening 61b of the through-hole 61a" refers to the open end of the through-hole 61a on the inner circumferential surface of the first cylindrical portion 61. Specifically, the insertion hole 72a is formed in the same shape as the opening 61b of the through-hole 61a, but has a smaller opening area than the through-hole 61a. In other words, the entire insertion hole 72a faces the through-hole 61a. Therefore, the cable 36 may come into contact with the insertion hole 72a but not with the opening 61b of the through-hole 61a. In this way, the cable protector 72 prevents the cable 36 from coming into contact with the opening 61b of the through-hole 61a.

[0035] As shown in Fig. 6, the cable protector 72 has a chamfered portion 72c formed at the opening 72b of the insertion hole 72a. The chamfered portion 72c is formed by chamfering the opening 72b of the insertion hole 72a. The chamfered portion 72c is formed at both of the two openings 72b of the insertion hole 72a. The chamfered portion 72c may be formed in a flat shape or a curved shape.

[0036] A pair of rotation stoppers 73 are provided circumferentially spaced apart and extend axially from the outer peripheral edge 71b of the main body 71. An engaging portion 48 of the case 41 of the torque sensor 40 is engaged with the rotation stopper 73. Specifically, a leaf spring 80 is provided between one end face of the rotation stopper 73 in the rotational direction and the engaging portion 48. The elastic force of the leaf spring 80 presses the engaging portion 48 against one of the rotation stoppers 73, thereby restricting relative rotation of the case 41 of the torque sensor 40 with respect to the housing 60. Note that the leaf spring 80 is not an essential component, and the engaging portion 48 of the case 41 of the torque sensor 40 may be sandwiched between the pair of rotation stoppers 73.

[0037] In the electric power steering device 100, the cable 36 may vibrate during assembly or while the vehicle is running. If the plate 70 were configured without the cable protector 72, the cable 36 might come into contact with the opening 61b of the through hole 61a of the first cylindrical portion 61, potentially damaging the cable 36. In this embodiment, as shown in FIG. 4 , the through hole 61a is formed to extend in a direction inclined with respect to a direction toward the center of the first cylindrical portion 61. In other words, the through hole 61a does not extend in the radial direction of the first cylindrical portion 61, but rather in a direction inclined with respect to the radial direction. Therefore, because the opening 61b of the through hole 61a is sharp, the cable 36 is likely to come into contact with the opening 61b and be damaged.

[0038] However, in the electric power steering device 100, the plate 70 is provided with a cable protector 72 that is capable of coming into contact with the cable 36 but that prevents the cable 36 from coming into contact with the opening 61 b ​​of the through hole 61 a. Therefore, even if the cable 36 vibrates during assembly of the electric power steering device 100 or while the vehicle is running, the cable 36 comes into contact with the cable protector 72 rather than the opening 61 b ​​of the through hole 61 a, and does not come into contact with the opening 61 b ​​of the through hole 61 a. Therefore, even if the through hole 61 a is formed to extend in a direction inclined with respect to the direction toward the center of the first cylindrical portion 61 and the opening 61 b ​​of the through hole 61 a is configured to be sharp, it is possible to prevent the cable 36 from coming into contact with the opening 61 b ​​of the through hole 61 a and being damaged.

[0039] Furthermore, the opening area of ​​the insertion hole 72a of the cable protector 72 is smaller than the opening area of ​​the through hole 61a of the housing 60. This makes it possible to easily prevent the cable 36 from coming into contact with the opening 61b of the through hole 61a and being damaged.

[0040] The cable protector 72 also has a chamfered portion 72c formed at the opening 72b of the insertion hole 72a. This prevents the cable 36 from coming into contact with the opening 72b of the insertion hole 72a of the cable protector 72 and being damaged. The chamfered portion 72c may be formed at only one of the two openings 72b of the insertion hole 72a. The chamfered portion 72c is not essential, and the cable protector 72 may not have the chamfered portion 72c.

[0041] Furthermore, the cable protection portion 72 is formed separately from the plate 70. This allows the cable 36 to be easily inserted through the insertion hole 72a of the cable protection portion 72 when assembling the electric power steering device 100. Specifically, the cable 36 is first inserted through the insertion hole 72a of the cable protection portion 72 inside the first cylindrical portion 61, and then the cable 36 is inserted through the through hole 61a and the cable protection portion 72 is attached to the plate 70, allowing the cable 36 to be guided out of the first cylindrical portion 61. Note that the cable protection portion 72 may be formed with a slit or the like for guiding the cable 36 into the insertion hole 72a. In this case, the cable 36 can be more easily inserted through the insertion hole 72a of the cable protection portion 72 via the slit or the like. Furthermore, the cable protection portion 72 may be formed integrally with the plate 70. In this case, the number of parts of the electric power steering device 100 can be reduced.

[0042] Furthermore, the connector 49 is held by the case 41 of the torque sensor 40, and the rotation stopper 73 and the cable protector 72 are provided at positions such that the cable 36 does not come into contact with the case 41 of the torque sensor 40. Specifically, as shown in FIGS. 4 and 5 , the connector 49, which is one end of the cable 36 within the first cylindrical portion 61, and the cable protector 72, which is the other end thereof, are provided so that the torque sensor 40 is not positioned to block the gap between them and so that the bent cable 36 does not come into contact with the case 41 of the torque sensor 40. This prevents the cable 36 from adversely affecting the detection accuracy of the torque sensor 40. Specifically, for example, the restoring force of the bent cable 36 is prevented from acting on the case 41 of the torque sensor 40, causing the torque sensor 40 to tilt.

[0043] According to the present embodiment described above, the following advantageous effects are achieved.

[0044] In the electric power steering device 100, the plate 70 is provided with a cable protector 72 that is capable of coming into contact with the cable 36 but that prevents the cable 36 from coming into contact with the opening 61b of the through hole 61a. Therefore, even if the cable 36 vibrates during assembly of the electric power steering device 100 or while the vehicle is running, the cable 36 comes into contact with the cable protector 72 rather than the opening 61b of the through hole 61a, and does not come into contact with the opening 61b of the through hole 61a. This prevents the cable 36 from coming into contact with the opening 61b of the through hole 61a and being damaged.

[0045] Next, modifications of the present embodiment will be described. The following modifications are also within the scope of the present invention, and it is possible to combine the following modifications with the configurations of the above embodiment, or to combine the following modifications with each other.

[0046] <Modification 1> In the above embodiment, the cable protector 72 is provided opposite the through hole 61 a of the first cylindrical portion 61, and the opening area of ​​the insertion hole 72 a of the cable protector 72 is smaller than the opening area of ​​the through hole 61 a of the housing 60. However, the cable protector 72 may be configured to at least contact the opening 61 b ​​of the through hole 61 a before the cable 36 contacts the opening 61 b ​​of the through hole 61 a when the cable 36 vibrates, thereby preventing the cable 36 from contacting the opening 61 b ​​of the through hole 61 a. For example, the cable protector 72 may be a pin that protrudes in the axial direction from the main body portion 71 of the plate 70, and the cable 36 may come into contact with the pin to prevent the cable 36 from contacting the opening 61 b ​​of the through hole 61 a.

[0047] <Modification 2> In the above embodiment, the entire insertion hole 72a of the cable protector 72 faces the through hole 61a, preventing the cable 36 from contacting the entire periphery of the opening 61b of the through hole 61a. However, the cable protector 72 may be configured so that a portion of the insertion hole 72a faces the through hole 61a, preventing the cable 36 from contacting a portion of the opening 61b of the through hole 61a. In this case, it is preferable that the cable protector 72 prevent the cable 36 from contacting sharp portions of the opening 61b of the through hole 61a.

[0048] <Modification 3> In the above embodiment, the cable protector 72 is formed in an inverted U shape and is provided in the mounting recess 71c of the outer peripheral edge 71b of the main body 71 of the plate 70. However, as shown in FIG. 7 , the cable protector may be a recess 172 formed in a part of the outer peripheral edge 71b of the main body 71 of the plate 170. Specifically, the recess 172 is formed on the outer peripheral edge 71b facing the through hole 61a of the first cylindrical portion 61. The recess 172 is formed radially through the outer peripheral edge 71b of the plate 170, which protrudes in the axial direction. The recess 172 is provided corresponding to the opening 61b of the through hole 61a and accommodates at least a portion of the cable 36. The recess 172 is formed so that the dimension in the circumferential direction of the first cylindrical portion 61 is smaller than the opening 61b of the through hole 61a. Therefore, when the cable 36 is accommodated in the recess 172, it does not come into contact with the opening 61b of the through hole 61a in the circumferential direction. In this configuration, it is possible to easily prevent the cable 36 from coming into contact with the opening 61b of the through-hole 61a and being damaged.

[0049] The configuration, operation, and effects of the embodiment of the present invention will be described below.

[0050] The electric power steering device 100 includes an input shaft 13 to which steering torque is input, an output shaft 15 connected to the input shaft 13 via a torsion bar 14, a torque sensor 40 attached across the input shaft 13 and the output shaft 15 and detecting the steering torque, a housing 60 having a first cylindrical portion 61 as a cylindrical portion and accommodating the torque sensor 40, an electric motor 21 that generates a steering assist torque based on the detection result of the torque sensor 40, and a through hole 61 formed through the first cylindrical portion 61 of the housing 60. 1a, and a cable 36 inserted into the through hole 61a and electrically connected to the torque sensor 40, the housing 60 has plates 70, 170 that close the opening of the first cylindrical portion 61, the torque sensor 40 has a connector 49 to which the cable 36 is connected, the through hole 61a is formed to extend in a direction inclined with respect to the direction toward the center of the first cylindrical portion 61, and the plates 70, 170 have cable protection portions 72, 172 that are capable of contacting the cable 36 and prevent the cable 36 from contacting the opening 61b of the through hole 61a.

[0051] In this configuration, the plates 70, 170 are provided with cable protectors 72, 172 that are capable of coming into contact with the cable 36 and that prevent the cable 36 from coming into contact with the opening 61 b ​​of the through hole 61 a. Therefore, even if the cable 36 vibrates during assembly of the electric power steering device 100 or while the vehicle is running, the cable 36 comes into contact with the cable protectors 72, 172 rather than the opening 61 b ​​of the through hole 61 a, and does not come into contact with the opening 61 b ​​of the through hole 61 a. Therefore, even in a configuration in which the through hole 61 a is formed to extend in a direction inclined with respect to the direction toward the center of the first cylindrical portion 61 and the opening 61 b ​​of the through hole 61 a is sharp, it is possible to prevent the cable 36 from coming into contact with the opening 61 b ​​of the through hole 61 a and being damaged.

[0052] In addition, in the electric power steering device 100, the cable protection portion 72 has an insertion hole 72a that is provided corresponding to the opening 61b of the through hole 61a and through which the cable 36 is inserted, and the opening area of ​​the insertion hole 72a of the cable protection portion 72 is smaller than the opening area of ​​the through hole 61a of the housing 60.

[0053] In this configuration, it is possible to easily prevent the cable 36 from coming into contact with the opening 61b of the through-hole 61a and being damaged.

[0054] In the electric power steering device 100, the cable protection portion 72 has a chamfered portion 72c formed at the opening 72b of the insertion hole 72a.

[0055] This configuration can prevent the cable 36 from coming into contact with the opening 72b of the insertion hole 72a of the cable protector 72 and being damaged.

[0056] Furthermore, in the electric power steering device 100 , the cable protection portion 72 is formed separately from the plate 70 .

[0057] In this configuration, the cable 36 can be easily inserted through the insertion hole 72 a of the cable protector 72 when assembling the electric power steering device 100 .

[0058] In addition, in the electric power steering device 100, the cable protection portion is a recess 172 formed by radially penetrating the outer peripheral edge 71b that protrudes in the axial direction on the plate 170, and the recess 172 is provided corresponding to the opening 61b of the through hole 61a to accommodate at least a portion of the cable 36, and the circumferential dimension of the first cylindrical portion 61 is formed to be smaller than the opening 61b.

[0059] In this configuration, it is possible to easily prevent the cable 36 from coming into contact with the opening 61b of the through-hole 61a and being damaged.

[0060] Furthermore, in the electric power steering device 100, the plates 70, 170 further have a rotation stopper 73 that restricts the rotation of the case 41 of the torque sensor 40, the connector 49 is held by the case 41 of the torque sensor 40, and the rotation stopper 73 and the cable protector 72, 172 are positioned so that the cable 36 does not come into contact with the torque sensor 40.

[0061] In this configuration, it is possible to prevent the cable 36 from adversely affecting the electric power steering device 100.

[0062] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

[0063] The torque sensor 40 may also function as an angle sensor that detects the absolute rotation angle of the steering shaft 11 .

[0064] In the above embodiment, the electric power steering device 100 is described as a single-pinion type in which the steering torque by the driver and the steering assist torque by the electric motor 21 are input to the rack shaft 12 via a common steering shaft 11. However, the electric power steering device 100 may be a dual-pinion type in which the steering torque by the driver and the steering assist torque by the electric motor 21 are each input independently to the rack shaft 12. Furthermore, the electric power steering device 100 is not limited to a rack-and-pinion type, and may also be a column assist type.

[0065] In the above embodiment, the torque sensor 40 is an inductance type sensor. However, the torque sensor 40 may be a magnetic type sensor, and the torque detection method is not limited.

[0066] This application claims priority based on Japanese Patent Application No. 2023-121699, filed with the Japan Patent Office on July 26, 2023, the entire contents of which are incorporated herein by reference.

Claims

1. An electric power steering device comprising: an input shaft to which steering torque is input; an output shaft connected to the input shaft via a torsion bar; a torque sensor attached across the input shaft and the output shaft and detecting the steering torque; a housing having a cylindrical portion and accommodating the torque sensor; an electric motor that generates steering assist torque based on the detection result of the torque sensor; a through hole formed through the cylindrical portion of the housing; and a cable that is inserted through the through hole and electrically connected to the torque sensor, wherein the housing has a plate that closes an opening of the cylindrical portion, the torque sensor has a connector to which the cable is connected, the through hole is formed to extend in a direction inclined with respect to a direction toward the center of the cylindrical portion, and the plate has a cable protector that is contactable with the cable and prevents the cable from contacting the opening of the through hole.

2. An electric power steering device according to claim 1, wherein the cable protection part has an insertion hole through which the cable is inserted, the insertion hole being provided in correspondence with the opening of the through hole, and the opening area of ​​the insertion hole in the cable protection part is smaller than the opening area of ​​the through hole in the housing.

3. An electric power steering device according to claim 2, wherein the cable protection section has a chamfered section formed at the opening of the insertion hole.

4. An electric power steering device according to claim 1, wherein the cable protection portion is formed separately from the plate.

5. An electric power steering device as claimed in claim 1, wherein the cable protection portion is a recess formed by penetrating radially through the outer peripheral edge of the plate which protrudes in the axial direction, the recess being provided in correspondence with the opening of the through hole to accommodate at least a portion of the cable, and the circumferential dimension of the cylindrical portion being formed smaller than that of the opening.

6. An electric power steering device according to claim 1, wherein the plate further has a rotation stopper portion that restricts rotation of the case of the torque sensor, the connector is held by the case of the torque sensor, and the rotation stopper portion and the cable protection portion are provided in positions such that the cable does not come into contact with the torque sensor.

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