Steering gear

Abstract

To improve the operational precision and reliability of the steering devices used in vehicle steering systems. [Solution] A steering device according to one aspect of the present invention comprises a first gear mechanism that receives the rotation of a steering wheel operation as input and converts the direction of the rotation and outputs it, and a second gear mechanism that receives the primary rotation output from the first gear mechanism as input and reduces the primary rotation and outputs it, wherein the second gear mechanism comprises a flange portion that forms one side of a gear case housing the reduction mechanism components of the second gear mechanism in the axial direction of the output shaft of the second gear mechanism, and a case portion that houses the conversion mechanism components of the first gear mechanism, wherein the flange portion and the case portion are integrally formed with each other.

Description

Technical Field

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

Background Art

[0002] Conventionally, an electric power steering system is known that reduces the steering operation force by a driver by applying the driving force of an electric motor in addition to the steering operation force by the driver to a steering mechanism of a vehicle. The steering device used in the electric power steering system can transmit the steering operation force to an output unit connected to the steering mechanism on the wheel side via a speed reducer and can also apply the driving force of the electric motor together (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the steering device of Patent Document 1 described above, there is a demand for a configuration that accurately determines the relative positions of a drive device such as an input mechanism that converts and outputs the direction of rotation of a steering operation, a speed reducer, and an electric motor, and improves the operating accuracy and reliability.

[0005] An object of the present invention is to improve the operating accuracy and reliability of a steering device used in a steering system of a vehicle.

Means for Solving the Problems

[0006] In order to solve the above problems, the present invention has adopted the following aspects. (1) A steering device according to one aspect of the present invention comprises a first gear mechanism that receives the rotation of a steering wheel operation as input and converts the direction of the rotation and outputs it, and a second gear mechanism that receives the primary rotation output from the first gear mechanism as input and reduces the primary rotation and outputs it, wherein the second gear mechanism comprises a flange portion that forms one side of a gear case housing the reduction mechanism components of the second gear mechanism in the axial direction of the output shaft of the second gear mechanism, and a case portion that houses the conversion mechanism components of the first gear mechanism, wherein the flange portion and the case portion are integrally formed with each other. With this configuration, the flange portion forming one axial side of the gear case of the second gear mechanism and the case portion of the first gear mechanism are integrally formed with each other, thereby reducing the number of parts and achieving weight reduction, as well as improving the accuracy of the relative position between the first gear mechanism and the second gear mechanism and improving operating accuracy.

[0007] (2) A steering device according to one aspect of the present invention comprises a plurality of fasteners for fixing the case body of the gear case to the flange portion, and a washer plate having a size that includes the seating surfaces of at least two of the plurality of fasteners. In this configuration, a washer plate for fastening the case body of the second gear mechanism to the flange is provided in a size that spans the seating surfaces of multiple fasteners. Compared to the case where each fastener has its own washer, the washer plate contacts the flange even in the margins between the fasteners. As a result, the surface pressure applied to the flange by tightening each fastener is reduced. Consequently, even when the flange is made of a light metal with low hardness, it is possible to ensure the tightening torque of each fastener while suppressing deformation of the seating surface side of the flange, thereby improving reliability.

[0008] (3) A steering device according to one aspect of the present invention is provided with a drive device that outputs a driving force to assist the steering operation, and a controller for controlling the drive of the drive device is arranged at one end of the drive device in the axial direction of the drive shaft of the drive device, the controller has a flattened shape with reduced thickness in the axial direction of the drive shaft, and has a larger outer diameter than the drive device when viewed from the axial direction of the drive shaft. With this configuration, the controller, which is located at the axial end of the drive unit, has a flattened shape with reduced thickness in the drive axial direction, and its outer diameter is larger than that of the drive unit when viewed in the drive axial direction. This allows for improved reliability by ensuring the size of the controller while keeping the axial dimensions of the drive unit, including the controller, down. [Effects of the Invention]

[0009] According to the present invention, it is possible to improve the operating accuracy and reliability of the steering device used in a vehicle's steering system. [Brief explanation of the drawing]

[0010] [Figure 1A] This is a schematic diagram of the steering assist device for a right-hand drive vehicle employing the steering unit of this embodiment. [Figure 1B] This is a schematic diagram of the steering assist device for a left-hand drive vehicle employing the steering unit of this embodiment. [Figure 2] This is a perspective view of the steering unit of this embodiment. [Figure 3] This is a perspective view of the steering unit of this embodiment, taken from a different direction than that shown in Figure 2. [Figure 4] This is a view of the steering unit as seen from the axial direction of the control input shaft. [Figure 5] This is a view of the steering unit shown above, from the axial direction of the output shaft. [Figure 6] This is a cross-sectional view along the line VI-VI in Figure 4, and it is a cross-sectional view of the first gear mechanism. [Figure 7] This diagram shows the components of the first and second gear mechanisms of the steering unit as viewed from the axial direction of the output shaft. [Figure 8] Figure 5 is a cross-sectional view along the line VIII-VIII, showing cross-sections of the first gear mechanism, the second gear mechanism, and the drive unit. [Figure 9] This is a perspective view showing the case, flange, and washer plate. [Figure 10A] This is a perspective view showing the conversion mechanism components of the first gear mechanism separated from the case. [Figure 10B] It is a perspective view showing a state in which the case flange member is inverted in the first axial direction with respect to FIG. 10A. [Figure 11] It is a view of the steering unit seen from the second axial direction, showing a modification of the arrangement of the drive device. [Figure 12A] It is a perspective view showing a first modification of the arrangement of the controller. [Figure 12B] It is a perspective view showing a second modification of the controller.

Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited only to this embodiment.

[0012] <Steering assist device 1> FIG. 1A is a schematic configuration diagram of a steering assist device 1 for a right-hand steering wheel vehicle adopting the steering unit (steering device) 10 of the present embodiment. FIG. 1B is a schematic configuration diagram of a steering assist device 1 for a left-hand steering wheel vehicle adopting the steering unit 10 of the present embodiment. In the figures, the line CL indicates the vehicle left-right center, the arrow LH indicates the left side of the vehicle, and the arrow RH indicates the right side of the vehicle, respectively.

[0013] As shown in FIGS. 1A and 1B, the steering assist device 1 includes a steering wheel 2, a steering shaft (column shaft) 3 to which a handle operating force (steering torque) is input from the steering wheel 2, a steering unit 10 connected to the tip (lower end) of the steering shaft 3, and a steering mechanism 6 that is operated by at least one of the steering torque passing through the steering unit 10 and an assist torque described later. The steering wheel 2 is arranged in front of the driver's seat of the vehicle and is rotated by the driver. The steering shaft 3 is integrally rotatably connected to the steering wheel 2 and extends below the steering wheel 2.

[0014] An output arm 7 is provided on the output shaft 25 (see Figures 2 and 3) of the steering unit 10. The tip of the output arm 7 is connected to the vehicle's steering mechanism 6. The steering mechanism 6 includes an operating arm 6a that receives output from the output arm 7, and tie rods 6b that steer the left and right front wheels W of the vehicle by operating the operating arm 6a. When at least one of steering torque and assist torque is output to the output shaft 25 of the steering unit 10, the output arm 7 swings, activating the steering mechanism 6 and steering the left and right front wheels W of the vehicle.

[0015] <Steering Unit 10> Figure 2 is a perspective view of the steering unit 10 of this embodiment. Figure 3 is a perspective view of the steering unit 10 of this embodiment, viewed from a different direction than in Figure 2. As shown in Figures 2 and 3, the steering unit 10 comprises a first gear mechanism 11, a second gear mechanism 20, and a drive unit 65. The first gear mechanism 11 is an operating mechanism to which the steering shaft 3 is connected, and converts the rotational motion of the steering shaft 3 around the central axis C1 (first axis) into rotational motion around a perpendicular axis C1a that is perpendicular to the first axis C1. The perpendicular axis C1a is provided parallel to the central axis (second axis) C2 of the output shaft 25, which will be described later.

[0016] Hereinafter, the direction parallel to the first axis C1 will be referred to as the first axis direction, and the direction parallel to the orthogonal axis C1a and the second axis C2 will be referred to as the second axis direction. In the diagram, arrow F1 indicates the first axis direction, arrow F2 indicates the second axis direction, and arrow F3 indicates the third direction perpendicular to both the first and second axis directions. Furthermore, the +f1 side of arrow F1 indicates one side of the first axis direction, and the -f1 side indicates the other side of the first axis direction; the +f2 side of arrow F2 indicates one side of the second axis direction, and the -f2 side indicates the other side of the second axis direction; and the +f3 side of arrow F3 indicates one side of the third direction, and the -f3 side indicates the other side of the third direction. Hereafter, symbols corresponding to the names of the directions and orientations described above may be used.

[0017] The second gear mechanism 20 is a reduction gear, and receives the primary rotation around the orthogonal axis C1a output by the first gear mechanism 11. The second gear mechanism 20 transmits the primary rotation while reducing its speed, and outputs it as a secondary rotation on an output shaft 25 parallel to the second axial direction F2 in the second gear mechanism 20. The second axial direction F2 may also be called the unit axial direction. The first gear mechanism 11 is adjacent to one side of the second gear mechanism 20 in the third direction +f3, and the drive unit 65 is adjacent to the other side of the second gear mechanism 20 in the third direction -f3.

[0018] The drive unit 65 is a rotating electric machine, and the axial direction of the drive shaft 67 (hereinafter referred to as the drive axis direction) is arranged parallel to the second axis direction F2. The drive unit 65 comprises a main body 66 having a cylindrical appearance and a drive shaft 67 protruding from one end of the main body 66 in the axial direction. In the figure, line C3 indicates the central axis (drive axis) of the drive shaft 67. The driving force of the drive unit 65 is reduced by the second gear mechanism 20 and transmitted to the steering mechanism 6. The driving force of the drive unit 65 is also reduced by the transmission mechanism 70, which will be described later, and input to the second gear mechanism 20. In this embodiment, the torque generated by the drive unit 65 is suppressed and its diameter is reduced by increasing the reduction ratio of the transmission mechanism 70. For example, the drive unit 65 has an outer shape A3 that is smaller in diameter than the outer shape A2 of the second gear mechanism 20 when viewed from the second axis direction F2.

[0019] At the other axial end of the drive unit 65, a controller (control device) 68 is provided, for example, which is elongated in the first axial direction F1 when viewed axially. The controller 68 has an electronic control device and a drive circuit that control the operation of the drive unit 65. The controller 68 has a flattened shape with reduced thickness in the drive axial direction. The controller 68 is larger than the main body 66 when viewed from the axial direction and has a case portion 68a that forms the exterior, and two drive circuits 68b and 68c divided within the case portion 68a in the longitudinal direction (first axial direction F1) of the axial shape. Each drive circuit 68b and 68c cooperates with each other to control the drive of the drive unit 65, and if one fails, the drive unit 65 is driven by the other alone, making it possible to generate, for example, about half the output of normal operation.

[0020] The driving force of the drive unit 65 is transmitted via a belt-type transmission mechanism 70 to the input shaft (hereinafter referred to as the second input shaft) 45, which is coaxially positioned with the output shaft 25 of the second gear mechanism 20. Steering torque, whose rotational direction has been converted via the first gear mechanism 11, is also input to the second input shaft 45 of the second gear mechanism 20. The first gear mechanism 11, the second gear mechanism 20, and the drive unit 65 are arranged in a third direction F3 (alignment direction) that is perpendicular to the first axial direction F1 and the second axial direction F2.

[0021] In the second axial direction F2, the width H3 of the main part of the drive unit 65 (excluding the partially protruding drive shaft 67, etc.) and the width H1 of the main part of the first gear mechanism 11 (excluding the partially protruding part) are arranged to fit within the width H2 of the main part of the second gear mechanism 20 (excluding the partially protruding output shaft 25, etc.). Each width H1, H2, and H3 is, for example, the width from the side surface 37a2 of the flange portion 37 on one side +f2 in the second axial direction to the tip of the target configuration on the other side -f2 in the second axial direction.

[0022] Thus, the first gear mechanism 11 (operating mechanism) that changes the direction of rotation of the steering wheel, the second gear mechanism (reduction gear) 20 that reduces the output of the first gear mechanism 11, and the drive unit 65 (rotating electric machine) that provides assist torque to assist the steering wheel are arranged overlapping in the second axial direction F2 of the second gear mechanism 20. This reduces the thickness of the steering unit 10 in the second axial direction F2, making it easier to arrange the steering unit 10 in the limited space available in the vehicle. The configuration is not limited to one in which the entire first gear mechanism 11 and the drive unit 65 are arranged within the width H2 of the second axial direction F2 of the second gear mechanism 20. It may also be a configuration in which at least a part of each of the first gear mechanism 11 and the drive unit 65 are arranged within the width H2 of the second axial direction F2 of the second gear mechanism 20.

[0023] The steering torque transmitted from the steering wheel 2 to the steering shaft 3 is input to the input section of the second gear mechanism 20 via the first gear mechanism 11. The input section of the second gear mechanism 20 (including the second input shaft 45 and multiple transmission gears 56) receives steering torque from the first gear mechanism 11 and assist torque from the drive unit 65. The second gear mechanism 20 combines the steering torque and assist torque input from the two systems and transmits this combined torque while reducing it in the gear section 40. The output section (output shaft 25) of the second gear mechanism 20 outputs the combined torque of the steering torque and assist torque, reduced at a specified reduction ratio. When the drive unit 65 fails, the steering torque is reduced by the second gear mechanism 20 and output with the assist torque at zero or reduced.

[0024] <First gear mechanism 11> Figure 4 is a view of the steering unit 10 from the axial direction of the operating input shaft 13. Figure 5 is a view of the steering unit 10 from the axial direction of the output shaft 15. Figure 6 is a cross-sectional view along the line VI-VI in Figure 4, showing a cross-section of the first gear mechanism 11. Figure 7 is a view of the mechanical components of the first gear mechanism 11 and the second gear mechanism 20 of the steering unit 10 from the axial direction of the output shaft 25. Figure 8 is a cross-sectional view along the line VIII-VIII in Figure 5, showing cross-sections of the first gear mechanism 11, the second gear mechanism 20, and the drive unit 65.

[0025] As shown in Figures 2 to 8, the first gear mechanism 11 comprises a case 12, an operating input shaft 13, a first bevel gear 14, a second bevel gear 15, a first output shaft 16, and a first output gear 17. In this embodiment, the mechanism components including each shaft 13, 16 and each gear 14, 15, 17 are collectively referred to as the conversion mechanism component 11d.

[0026] The case portion 12 is integrally formed with the unit case 10c. The unit case 10c includes a gear case 21 that houses the reduction mechanism components 20d, such as the gears in the second gear mechanism 20, and functions as the frame for the entire steering unit 10. The case portion 12 has a cylindrical shape that extends in the first axial direction F1.

[0027] The end (opening) of the case portion 12 on one side in the first axial direction +f1 (upper side, steering shaft 3 side) is closed by attaching the first plug body 12a. The first plug body 12a supports the first shaft portion 13a, which constitutes the first axial direction +f1 of the operating input shaft 13, via a pair of bearings 12b. The operating input shaft 13 is divided into a first shaft portion 13a, a second shaft portion 13b, and a third shaft portion 13c in the order from the first axial direction +f1 to the other side in the first axial direction -f1. The second shaft portion 13b is further divided into a first divided portion 13b1 on the first axial direction +f1 and a second divided portion 13b2 on the other side in the first axial direction -f1. The end (opening) of the case portion 12 on the other side of the first axial direction -f1 (lower side, steering mechanism 6 side) is closed by attaching the second plug body 12c. The third shaft portion 13c of the operating input shaft 13 is supported by the second plug body 12c via a pair of bearings 12d.

[0028] On one side of the case portion 12 that is perpendicular to the first axial direction F1 and the second axial direction F2 (second axial direction side + f2, the side of the transmission mechanism 70 described later), a bottomed cylindrical radial projection 12e is integrally formed, opening toward the second axial direction side + f2. The radial projection 12e forms a defined internal space K1 when the cover portion 72a, described later, is attached from the second axial direction side + f2. The internal space K1 houses a first output shaft 16 along the second axial direction F2, a pair of bearings 16b that support the first output shaft 16, and a cylindrical support portion 18 that supports the pair of bearings 16b.

[0029] A bottomed cylindrical socket portion 13as is formed on the other side -f1 in the first axial direction of the first shaft portion 13a, opening toward the other side -f1 in the first axial direction. One side +f1 in the first axial direction of the second shaft portion 13b is inserted into this socket portion 13as and connected so as to be able to rotate as a whole by spline fitting or the like. A bottomed cylindrical socket portion 13bs is formed on the other side -f1 in the first axial direction of the second shaft portion 13b, opening toward the other side -f1 in the first axial direction. One side +f1 in the first axial direction of the third shaft portion 13c is inserted into this socket portion 13bs and connected so as to be able to rotate as a whole by spline fitting or the like.

[0030] The first and second parts 13b1 and 13b2 of the second shaft section 13b are each hollow, and a torsion bar 13b3 is inserted through them along the first axis C1. The first and second parts 13b1 and 13b2 rotate together via the torsion bar 13b3, but relative rotation occurs due to the torsional deformation of the torsion bar 13b3. A sensor 19 is provided on the outer circumference of the second shaft section 13b to detect the relative rotation of the first and second parts 13b1 and 13b2. The detection information from this sensor 19 is input to a controller 68 that controls the drive unit 65. Based on the detection information from the sensor 19, the controller 68 calculates the steering torque and rotational speed of the steering wheel operation and controls the output of the drive unit 65. The steering of the steering wheel 2 by the driver is assisted by the torque of the drive unit 65 controlled by the controller 68.

[0031] The first bevel gear 14 is supported coaxially and integrally rotatably at the middle of the third shaft portion 13c. The second bevel gear 15 meshes with the first bevel gear 14. The second bevel gear 15 is supported coaxially and integrally rotatably at the tip of the first output shaft 16. The first output shaft 16 supports the first output gear 17 coaxially and integrally so as to be rotatable. The first output gear 17 meshes with the operating side transmission gear 56a of the second gear mechanism 20.

[0032] The first gear mechanism 11 is configured as an orthogonal input / output mechanism by arranging the first output shaft 16 so as to be perpendicular to the operating input shaft 13. The first gear mechanism 11 transmits the rotational force of the operating input shaft 13 to the first bevel gear 14 when, for example, the operator rotates the operating input shaft 13 by operating it. The rotational force of the first bevel gear 14 is transmitted to the transmission gear 56 via the second bevel gear 15, the first output shaft 16, and the first output gear 17.

[0033] Here, the first bevel gear 14, supported by the third shaft portion 13c, is in contact with the inner ring of the adjacent bearing 12d on the other side of the first axial direction -f1 via a shim 14s. The pair of bearings 2d are supported on the inner circumference of the second plug body 12c, with their movement in the first axial direction F1 restricted. The bearing 12d adjacent to the first bevel gear 14 on the other side of the first axial direction -f1 receives the thrust load of the first bevel gear 14 via the shim 14s. By adjusting the thickness of this shim 14s, the backlash between the first bevel gear 14 and the second bevel gear 15 can be reduced.

[0034] <Second gear mechanism 20> As shown in Figures 7 and 8, the second gear mechanism 20 is configured, for example, as an eccentric oscillating transmission. The second gear mechanism 20 comprises a gear case 21, a gear section 40, and three crank assemblies 50. The gear case 21 houses the gear section 40 and the three crank assemblies 50. In this embodiment, the mechanism components including the gear section 40 and the three crank assemblies 50 are collectively referred to as the reduction gear mechanism components 20d.

[0035] The gear case 21 comprises a first case (carrier case) 22 having a fixing portion to the vehicle body, and a second case (outer cylinder case) 23 that is cylindrical in shape around the central axis (second axis) C2 of the output shaft 25 and is rotatably mounted relative to the first case 22. The second case 23 is supported on its outer circumference via a pair of axially spaced main bearings 24. The second case 23 is an example of an output member of the second gear mechanism 20. When the second case 23 is fixed to a support portion 18 such as the vehicle body, the second case 23 becomes the output member.

[0036] The first case 22 includes a base 27, an end plate 28, a positioning pin 29, and a fixing bolt 31. Overall, the first case 22 has a cylindrical shape coaxial with the output shaft 25. The first case 22 functions as a carrier supporting three crank assemblies 50. The base portion 27 includes a base plate portion 32 and three shaft portions 33. Each of the three shaft portions 33 extends from the base plate portion 32 to the other side -f2 in the second axial direction. The end plate portion 28 is attached to the base portion 27 on the opposite side of the base plate portion 32 in the axial direction. The three shaft portions 33 pass through the gear portion 40 and are connected to the end plate portion 28.

[0037] Screw holes 35 and reamed holes 36 are formed on the end faces of each of the three shaft portions 33. Positioning pins 29 are inserted into the reamed holes 36. As a result, the end plate portion 28 is precisely positioned relative to the base portion 27. Fixing bolts 31 are screwed into the screw holes 35. As a result, the end plate portion 28 is fixed to the base portion 27. A flange portion 37 is attached to one side +f2 of the base plate portion 32 of the first case 22 in the second axial direction. The flange portion 37 forms an oil chamber R1 between itself and a disc portion 25a provided on the base end side of the output shaft 25, which houses the reduction mechanism components 20d of the second gear mechanism 20. A specified amount of gear oil is stored in the oil chamber R1, enabling lubrication of the reduction mechanism components 20d.

[0038] The outer circumference of the disc portion 25a is fixed to the other end of the second case 23 in the second axial direction -f2 by a plurality of bolts B1 arranged in the circumferential direction. The end of the second case 23 in the second axial direction +f2 fits into the opening of a bottomed cylindrical recess 37a1 formed in the flange portion 37. An oil seal 23c is interposed between the outer circumference of the end of the second case 23 in the second axial direction +f2 and the inner circumference of the opening of the recess 37a1 in the flange portion 37. An oil seal 45c is interposed between the outer circumference of the second input shaft 45 and the inner circumference of the shaft insertion hole in the flange portion 37.

[0039] The oil chamber R1 communicates with the internal space K1 of the radial projection 12e of the case portion 12 of the first gear mechanism 11 through the space where the meshing portion between the transmission gear 56 and the first output gear 17 of the first gear mechanism 11 is located. The internal space K1 of the radial projection 12e is a communication space that communicates with the oil chamber R1. The cylindrical internal space within the case portion 12 that houses the bevel gear is a separated space K2 that is oil-tightly separated from the internal space K1 via an oil seal 16c.

[0040] Here, since the rotational speed of each gear in the first gear mechanism 11 is lower than that of the second gear mechanism 20, the gear housings are not oil chambers R1, but rather each gear is coated with grease or the like. This reduces the amount of oil to be filled into the steering unit 10, resulting in weight reduction, cost reduction, and reduced friction due to oil agitation in low-temperature environments.

[0041] Furthermore, if an oil chamber R1 is formed in the first gear mechanism 11, a dedicated oil seal may be required around the sensors to prevent oil from adhering to the sensors installed in the first gear mechanism 11. In contrast, if the oil chamber R1 is not formed in the first gear mechanism 11, a general oil seal 16c can be provided between the first gear mechanism 11 and the second gear mechanism 20, thus reducing costs in this respect as well.

[0042] On the outside of the flange portion 37, there are multiple fastening bosses 37b, which serve as fixing points to the vehicle body. Each fastening boss 37b is cylindrical in shape, for example, along the second axial direction F2. The second case 23 has a plurality of internal tooth pins (internal teeth) 26 on its inner circumferential surface. Each internal tooth pin 26 is a cylindrical member extending parallel to the second axis C2. Each internal tooth pin 26 is fitted into a pin groove formed in the inner wall of the second case 23. Each internal tooth pin 26 is properly held by the second case 23.

[0043] Multiple internal tooth pins 26 are arranged at equal intervals in the circumferential direction around the second axis C2. The half-circumferential surface of each internal tooth pin 26 protrudes inward from the inner wall of the second case 23. Multiple internal tooth pins 26 function as internal teeth that mesh with the external teeth of the gear portion 40.

[0044] The gear section 40 is positioned between the base plate section 32 and the end plate section 28. The gear section 40 includes two oscillating gears (external tooth members) 41 and 42. The oscillating gear 41 is positioned between the base plate section 32 and the oscillating gear 42 and has external teeth that mesh with a plurality of internal tooth pins 26. The oscillating gear 42 is positioned between the end plate section 28 and the oscillating gear 41 and has external teeth that mesh with a plurality of internal tooth pins 26. The external teeth of each oscillating gear 41 and 42 have a smoothly continuous wave shape throughout the entire circumferential direction of each oscillating gear 41 and 42.

[0045] The two oscillating gears 41 and 42 are identical in shape and size. The two oscillating gears 41 and 42 rotate around the second case 23 while meshing with the internal tooth pin 26 of the second case 23. At this time, the centers of the two oscillating gears 41 and 42 rotate around the second axis C2. This movement of each oscillating gear 41 and 42 is called "oscillating rotation".

[0046] As each oscillating gear 41, 42 oscillates, each time the center of each oscillating gear 41, 42 completes one revolution around the second axis C2, a relative rotation occurs between each oscillating gear 41, 42 and the second case 23 by an angle corresponding to the difference in the number of teeth between the external teeth of each oscillating gear 41, 42 and the internal teeth (internal tooth pin 26) of the second case 23.

[0047] The rotational phases of the two oscillating gears 41 and 42 are offset by 180° from each other. While one oscillating gear 41 engages with half of the internal tooth pins 26, the other oscillating gear 42 engages with the remaining half of the internal tooth pins 26. Therefore, the gear section 40 generates relative rotational torque between the first case 22 and the second case 23 at two points where each oscillating gear 41 or 42 engages with the second case 23.

[0048] Each of the three crank assemblies 50 includes a crankshaft 51, four bearings 52, 53, 54, and 55, and a transmission gear 56. The three crank assemblies 50 are arranged at equal intervals in the circumferential direction around the second axis C2. The line C2a in the figure indicates the rotational axis (crank axis) of each crank shaft 51. Each crank axis C2a is parallel to the second axis direction F2 and parallel to the second axis C2. Each crank shaft 51 rotates around its respective crank axis C2a.

[0049] Each crankshaft 51 includes two journals (crank journals) 58, 59 and two eccentric portions (eccentric bodies) 61, 62. The two journals 58, 59 are each cylindrical in shape with the crank axis C2a at its center. Journal 58 on one side of the second axial direction +f2 is supported by the base 27 via a first bearing 52. Journal 59 on the other side of the second axial direction -f2 is supported by the end plate portion 28 via a second bearing 53.

[0050] In each crankshaft 51, two eccentric portions 61 and 62 are formed between two journals 58 and 59. The two eccentric portions 61 and 62 have central axes that are eccentric with respect to the corresponding crankshaft axis C2a and are cylindrical in shape that are eccentric with respect to the two journals 58 and 59.

[0051] The eccentric portion 61 with a second axial direction of +f2 on one side is inserted into the third bearing 54 and, together with the third bearing 54, is inserted into the crank insertion hole of the oscillating gear 41 with a second axial direction of +f2 on one side. The oscillating gear 41 with a second axial direction of +f2 on one side undergoes eccentric motion due to the rotation of the eccentric portion 61 with a second axial direction of +f2 on one side. The eccentric portion 62 on the other side of the second axial direction -f2 is inserted into the fourth bearing 55 and, together with the fourth bearing 55, is inserted into the crank insertion hole of the oscillating gear 42 on the other side of the second axial direction -f2. The oscillating gear 42 on the other side of the second axial direction -f2 undergoes eccentric motion due to the rotation of the eccentric portion 62 on the other side of the second axial direction -f2.

[0052] Each transmission gear 56 is meshed with a second input gear 46 that is coaxial with the second input shaft 45. The second input gear 46 is integrally formed on the outer circumference of the second input shaft 45, for example. The second input shaft 45 is coaxial with and integrally formed with the output shaft (transmitter output shaft 76b) of the transmission mechanism 70. The second input gear 46 is also a transmission output gear integrally formed with the transmission output shaft 76b.

[0053] The driven pulley support shaft 76a, which is connected to the second axial side +f2 of the transmission output shaft 76b, is rotatably supported via a bearing 37d on the shaft support portion 37c of the flange portion 37 that closes the second axial side +f2 of the gear case 21. The shaft portion 47, which is connected to the other second axial side -f2 of the second input shaft 45, extends beyond the transmission gear 56 into the second gear mechanism 20 in the second axial direction F2, and is supported via a bearing 21d on the shaft support portion 21c of the gear case 21 (e.g., base portion 32) of the second gear mechanism 20.

[0054] The three transmission gears 56 on each crankshaft 51 are arranged at equal intervals in the circumferential direction (in a triangular shape) around the second input gear 46, and each gear meshes with the second input gear 46. The second input gear 46 has a smaller diameter than each transmission gear 56, and each transmission gear 56 reduces the rotation input from the second input gear 46. The three transmission gears 56 are arranged inside the circular outer shape A2 of the second gear mechanism 20 when viewed from the second axial direction F2. The output of the reduced drive unit 65 is transmitted to the second input gear 46 via the transmission mechanism 70.

[0055] Of the three transmission gears 56, the transmission gear 56a on the first gear mechanism 11 side (hereinafter referred to as the operating side transmission gear) has its central axis (crank axis C2a) positioned on a plane S1 shown as a straight line in Figure 5. Plane S1 is a plane that aligns with the second axial direction F2 and the third direction F3, and is perpendicular to the first axial direction F1. The first output gear 17 of the first gear mechanism 11 meshes with the operating side transmission gear 56a. The first output gear 17 has a larger diameter than the operating side transmission gear 56a, and the operating side transmission gear 56a increases the speed of the rotation input from the first output gear 17.

[0056] Each transmission gear 56 receives the driving force generated by the drive unit 65 via the transmission mechanism 70. By using one of the three transmission gears 56 (the operating transmission gear 56a) as an input gear that receives rotation from both the first gear mechanism 11 and the drive unit 65, the number of parts is reduced and the size is miniaturized compared to the case where separate input gears are provided for each of the first gear mechanism 11 and the drive unit 65.

[0057] When the driving force of the drive unit 65 is input to each transmission gear 56, each crankshaft 51 rotates around the crank axis C2a. As a result, the two eccentric portions 61 and 62 of each crankshaft 51 rotate eccentrically around the corresponding crank axis C2a. The first output gear 17, viewed from the second axial direction F2, crosses the outer shape A2 of the second gear mechanism 20 and meshes with the operating transmission gear 56a.

[0058] Two oscillating gears 41 and 42, connected to each eccentric portion 61 and 62, oscillate and rotate within the circular space defined by the second case 23. Each of the two oscillating gears 41 and 42 meshes with an internal tooth pin 26 of the second case 23, and the oscillating rotation of these two oscillating gears 41 and 42 generates relative rotational motion between the first case 22 and the second case 23. By causing each oscillating gear 41 and 42 to oscillate through the eccentric rotation of each crankshaft 51, a reduced output rotation is obtained from the input rotation.

[0059] In this configuration, when the steering wheel 2 is rotated, the steering force transmitted via the first gear mechanism 11 is transmitted to one of the three transmission gears 56 (the operating transmission gear 56a). In this power transmission, the steering force is increased because the first output gear 17 of the first gear mechanism 11 has a larger diameter than the transmission gear 56. The steering force input to one of the three transmission gears 56 is also transmitted to the other two transmission gears 56 via the second input gear 46.

[0060] At this time, the sensor 19 in the first gear mechanism 11 detects the twist of the operating input shaft 13, and the controller 68 drives the drive unit 65 in response to this detection information. The driving force of the drive unit 65 is reduced in the transmission mechanism 70 and transmitted to the second input shaft 45, and further transmitted from the second input gear 46 to the three transmission gears 56. In the power transmission from the second input gear 46 to each transmission gear 56, the driving force of the drive unit 65 is reduced.

[0061] The second gear mechanism 20 rotates the first eccentric portion 61 and the second eccentric portion 62 of each crankshaft 51 eccentrically by the combined force of the handle operating force and motor driving force input to each transmission gear 56, causing the first oscillating gear 41 and the second oscillating gear 42 to oscillate with a predetermined phase difference. In the event of a failure of the drive device 65 or each drive circuit 68b, 68c, the assist torque from the drive device 65 becomes zero or decreases, and the handle operating force rotates each crankshaft 51 to oscillate the first oscillating gear 41 and the second oscillating gear 42.

[0062] The first oscillating gear 41 and the second oscillating gear 42 oscillate within the second case 23, overcoming the internal tooth pin 26 with their first and second external teeth. This creates a relative rotation between the second case 23, which supports the first and second oscillating gears 41 and 42, and the second case 23, which holds the internal tooth pin 26, with a significant reduction in rotational speed relative to the input rotation. By fixing one of the second cases 23 to a support part 18 such as a vehicle body and using the other as an output member, an eccentric oscillating gear device is constructed that outputs a significantly reduced input rotation.

[0063] <Transmission mechanism 70> As shown in Figures 2 and 3, the transmission mechanism 70 is provided on one side of the unit case 10c in the second axial direction +f2. The transmission mechanism 70 enables the power of the drive unit 65 to be transmitted to the second input shaft 45 of the second gear mechanism 20. The transmission mechanism 70 is provided in an area that spans both the drive unit 65 and the second gear mechanism 20 when viewed from the axial direction.

[0064] The transmission mechanism 70 comprises a transmission case 71, a drive pulley 75, a driven pulley 76, a transmission belt 77, and a tensioner 78. In this embodiment, the mechanism components, including each of the pulleys 75, 76, the transmission belt 77, and the tensioner 78, are collectively referred to as the transmission mechanism components 70d.

[0065] The transmission case 71 comprises a case body 72 fixed to one side +f2 of the second axial direction of the flange portion 37 by a plurality of bolts B3, and a case cover 73 that closes the open portion of the case body 72 on one side +f2 of the second axial direction. For illustrative purposes, the case cover 73 is omitted in Figure 2. On one side +f3 in the third direction of the case body 72, a cover portion 72a is integrally formed, extending beyond the housing portion of the driven pulley 76 to a position that overlaps with the first gear mechanism 11 (a position that avoids the second gear mechanism 20) when viewed from the second axial direction F2. The cover portion 72a closes the open portion of the radial projection 12e of the case portion 21 of the first gear mechanism 11 from one side +f2 of the second axial direction.

[0066] The cover portion 72a has a plurality of fastening portions 72b for the case portion 21 on its outer circumference when viewed from the second axial direction F2, and a bulging portion 72c is formed on its inner circumference when viewed from the axial direction, which bulges out in one direction +f2 in the second axial direction compared to the fastening portions 72b.

[0067] The bulge 72c covers the tip of the first output shaft 16 of the first gear mechanism 11 from one side +f2 in the second axial direction. The bulge 72c is formed within the width H4 (excluding partial protrusions) of the main part of the transmission case 71 in the second axial direction F2, thereby suppressing an increase in the size of the second axial direction F2. The width H4 is, for example, the width from the side surface 37a2 of the flange portion 37 on one side +f2 in the second axial direction to the tip of the transmission case 71 on one side +f2 in the second axial direction.

[0068] An internal space K1 is formed inside the bulge 72c, which communicates with the oil chamber R1 in the gear case 21 of the second gear mechanism 20. The internal space K1 is formed outside the outer shape A2 of the second gear mechanism 20 when viewed from the second axial direction F2. Providing the internal space K1 makes it easier to secure a ratio of space (excess space not filled with oil) to the total volume of the oil chamber.

[0069] On the other hand, the internal space in the transmission case 71 that houses the pulleys 75, 76 and the transmission belt 77, and other transmission mechanism components 70d, is a second separation space K3 that is oil-tightly separated from the oil chamber R1 of the second gear mechanism 20 by an oil seal 16c. By making the transmission mechanism 70 oil-less, reliable power transmission by the transmission belt 77 becomes possible, and the oil seal on the drive unit 65 side becomes unnecessary.

[0070] The drive pulley 75 is positioned coaxially with the drive shaft 67 of the drive unit 65 and is mounted integrally and rotatably on a drive pulley support shaft 75a, which is provided to extend the drive shaft 67. The driven pulley 76 is positioned coaxially with the second input shaft 45 of the second gear mechanism 20 and is integrally rotatable on a driven pulley support shaft 76a, which is provided to extend the second input shaft 45.

[0071] The driven pulley 76 has a larger diameter than the drive pulley 75 and reduces the rotation input from the drive pulley 75. The transmission mechanism 70 reduces the output of the drive unit 65 and transmits it to the second gear mechanism 20. Although simplified in the drawing, the transmission belt 77 is, for example, a toothed belt, enabling reliable torque transmission.

[0072] Inside the transmission case 71, a second separation space K3 is formed, separated from the oil chamber R1 in the second gear mechanism 20 by an oil seal 45c provided on the outer circumference of the second input shaft 45 and an O-ring 37c1 provided on the outer circumference of the shaft support portion 37c of the flange portion 37. In this embodiment, the oil seal 45c and the O-ring 37c1 are collectively referred to as the second oil seal. The second separation space K3 is oil-free and suppresses slippage of the transmission belt 77. The drive shaft 67 of the drive unit 65 faces the second separation space K3, but oil does not reach the drive unit 65 even if an oil seal is not provided on the outer circumference of this drive shaft 67.

[0073] <Case / Flange Molded Product 38> Figure 9 is a perspective view showing a case-flange molded product 38, which integrates a flange portion 37 and a case portion 12 that form part of the unit case 10c, as well as a washer plate 39 to be attached to the case-flange molded product 38. As shown in Figure 9, the flange portion 37 is integrally formed from the same material as the case portion 12 of the first gear mechanism 11. The flange portion 37 and the case portion 12 are integrally formed by casting or the like to form a molded product (case-flange member 38). Made of aluminum alloy, the flange portion 37 includes a base portion 37a that forms a shallow, bottomed cylindrical recess 37a1 and closes one axial end of the case of the second gear mechanism 20, and a plurality of fastening bosses 37b that protrude outward from the outer circumference of the base portion 37a.

[0074] The case portion 12 is located on one side +f3 in the third direction of the substrate portion 37a and is displaced -f2 on the other side in the second axial direction from the substrate portion 37a. The radial projection 12e formed on one side +f2 in the second axial direction of the case portion 12 is provided so as to be connected to one side +f3 in the third direction of the substrate portion 37a of the flange portion 37. The radial projection 12e and the substrate portion 37a form a continuous opening periphery along a plane (side surface) perpendicular to the second axial direction F2.

[0075] Multiple fastening bolts B2 are attached to the base plate portion 37a to secure the first case 22 (carrier) of the gear case 21 of the second gear mechanism 20. The multiple fastening bolts B2 are arranged in a specified number (7 bolts) in each of three regions that avoid the three transmission gears 56 when viewed from the second axial direction F2. Corresponding to these specified number of fastening bolts B2, a fan-shaped washer plate 39 is provided when viewed from the second axial direction F2.

[0076] Each washer plate 39 is made of an iron-based material including steel and has higher hardness than the case / flange member 38. Each washer plate 39 has multiple insertion holes through which the specified number of fastening bolts B2 are inserted, and contacts one side surface of the base plate 37a over a large area including not only the individual bolt seating surfaces but also the area between adjacent bolts and the area outside the bolt insertion range.

[0077] As a result, the surface pressure on the case-flange member 38 due to bolt fastening is reduced, so that even when the fastening bolts B2 are tightened to the specified tightening torque, deformation of the case-flange member 38 made of a light alloy such as aluminum alloy is suppressed. Therefore, the first case 22 of the second gear mechanism 20 can be securely fixed to the case-flange member 38.

[0078] <Reversed arrangement of the first gear mechanism 11> Figure 10A is a perspective view showing the conversion mechanism component 11d of the first gear mechanism 11 separated from the case portion 12. Figure 10B is a perspective view showing the case flange member 38 reversed in the first axial direction F1 compared to Figure 10A. As shown in Figures 10A and 10B, the conversion mechanism component 11d of the first gear mechanism 11 is separable in the axial direction (first axial direction F1) of the operating input shaft 13.

[0079] The first gear mechanism 11 allows the third shaft portion 13c to be inserted into and removed from the socket portion 13bs of the second shaft portion 13b by movement along the first axial direction F1. The mechanical components on one side +f1 of the first axial direction of the socket portion 13bs form a first assembly including the first plug body 12a and the sensor 19. The first assembly is detachable from the case portion 12 from one side +f1 of the first axial direction along the first axial direction F1. The mechanical components on the other side -f1 of the first axial direction of the socket portion 13bs form a second assembly including the second plug body 12c and the first bevel gear 14. The second assembly is detachable from the case portion 12 from the other side -f1 of the first axial direction along the first axial direction F1.

[0080] The case portion 12 has openings on both sides of the first axial direction F1 that are symmetrical with respect to the first axial direction F1. The central axis (orthogonal axis C1a) of the second bevel gear 15 and the first output shaft 16 is located at the center of the first axial direction F1 of the case portion 12. The central axis C1a of the second bevel gear 15 is positioned to intersect with the central axis (first axis C1) of the first bevel gear 14. The second bevel gear 15 can mesh with the first bevel gear 14 regardless of which side of the first axial direction F1 the second assembly is attached to the case portion 12 from. Furthermore, if the second assembly is attached from either side of the first axial direction F1 of the case portion 12, the socket portion 13bs of the second shaft portion 13b and the third shaft portion 13c can be connected by attaching the first assembly from the opposite side of the first axial direction F1 of the case portion 12. In other words, the first gear mechanism 11 can be mounted on the case portion 12 in either a standard configuration (see, for example, Figure 10A) or a reverse configuration in which the first axial direction F1 is reversed compared to the standard configuration (see, for example, Figure 10B).

[0081] Here, the case-flange member 38 is formed symmetrically with respect to a plane S1 (see Figure 5) along the second axial direction F2 and the third direction F3. In Figures 10A and 10B, the arrangement of the case-flange member 38 is shown inverted, rather than the arrangement of the first gear mechanism 11. As shown in Figures 10A and 10B, by reversing the arrangement of the case-flange member 38 (and thus the arrangement of the steering unit 10) and mounting it on the vehicle, the steering unit 10 can be mounted on both right-hand drive and left-hand drive vehicles.

[0082] Generally, the steering unit 10 requires a change in the layout of its input / output sections to accommodate the difference between right-hand drive and left-hand drive vehicles. For this reason, the steering unit 10 may require separate frames for right-hand drive and left-hand drive vehicles.

[0083] The steering unit 10 of this embodiment allows for the reversal of the first gear mechanism 11's arrangement, and the case-flange member 38 is formed symmetrically with respect to a plane S1 (a plane perpendicular to the first axis direction F1) along the second axis direction F2 and the third direction F3. As shown in Figures 10A and 10B, the steering unit 10 can be mounted on the vehicle with its arrangement reversed. This makes it possible to rearrange the case-flange member 38 and the first gear mechanism 11 according to whether the vehicle is right-hand drive or left-hand drive, thereby enabling the use of common parts while accommodating the differences between right-hand drive and left-hand drive configurations for input / output sections.

[0084] As described above, the steering unit 10 in the above embodiment includes a first gear mechanism 11 that receives the rotation of the steering wheel operation as input and converts the direction of this rotation before outputting it, and a second gear mechanism 20 that receives the primary rotation output from the first gear mechanism 11 as input and reduces this primary rotation before outputting it, and at least a part of the first gear mechanism 11 is arranged within the width H2 of the second gear mechanism 20 in the axial direction (second axial direction F2) of the output shaft (second output shaft 25) of the second gear mechanism 20. In this configuration, the first gear mechanism 11 (operating mechanism) that changes the direction of rotation of the handle operation and the second gear mechanism (reducer) 20 that reduces the output of the first gear mechanism 11 are arranged to overlap each other in the second axial direction F2 of the second gear mechanism 20, thereby reducing the thickness of the entire device in the second axial direction F2 and enabling miniaturization.

[0085] Furthermore, in the steering unit 10 described above, The vehicle is equipped with a drive unit 65 that outputs a driving force to assist in steering, and at least a portion of the drive unit 65 is positioned within the width H2 of the second gear mechanism 20 in the second axial direction F2. With this configuration, the drive unit 65 (assist motor) that outputs steering assist force is arranged to overlap with each other in the second axial direction F2 of the second gear mechanism 20, thereby reducing the thickness of the entire device including the drive unit 65 in the second axial direction F2 and enabling further miniaturization.

[0086] Furthermore, in the steering unit 10 described above, the second gear mechanism 20 has the primary input gear (operating side transmission gear 56a) positioned inward from the outer shape A2 as viewed from the second axial direction F2, and the first gear mechanism 11 has the first output gear 17, which has a larger diameter than the operating side transmission gear 56a, meshed with the operating side transmission gear 56a. In this configuration, the second gear mechanism 20 is made smaller by positioning the operating-side transmission gear 56a inside the outer shape A2 of the second gear mechanism 20 when viewed from the second axial direction F2. The first output gear 17 of the first gear mechanism 11 has a larger diameter than the operating-side transmission gear 56a and meshes with the operating-side transmission gear 56a, thereby ensuring a distance between the first gear mechanism 11 and the second gear mechanism 20, enabling power transmission between the two gear mechanisms 11 and 20, and increasing the rotational output of the first gear mechanism 11 before transmitting it to the second gear mechanism 20.

[0087] Furthermore, in the steering unit 10 described above, the drive unit 65 and the second gear mechanism 20 are connected via a transmission mechanism 70, and the transmission mechanism 70 reduces the output of the drive unit 65 and transmits it to the second gear mechanism 20. With this configuration, the torque generated by the drive unit 65 is reduced and transmitted to the second gear mechanism 20, thereby enabling the drive unit 65 to be made smaller.

[0088] Furthermore, in the steering unit 10 described above, the second gear mechanism 20 is equipped with a second input gear 46 that meshes with the transmission gear 56, which includes the operating side transmission gear 56a, and has a smaller diameter than the transmission gear 56, and the transmission mechanism 70 transmits the output of the drive unit 65 to the second input gear 46. With this configuration, by transmitting the output of the drive unit 65 to the second input gear 46 of the second gear mechanism 20, the output of the drive unit 65 can be further reduced, thereby suppressing the output torque of the drive unit 65 and enabling miniaturization.

[0089] Furthermore, in the steering unit 10 described above, the drive unit 65 has a drive shaft 67 parallel to the second output shaft 25 of the second gear mechanism 20, and when viewed from the second axial direction F2, the drive unit 65 has an outer shape A3 that is smaller than the outer shape A2 of the second gear mechanism 20. With this configuration, by arranging the drive unit 65 and the second gear mechanism 20 in parallel with their axial directions parallel to each other, the overall size of the device can be reduced in the second axial direction F2 compared to the case where the drive unit 65 and the second gear mechanism 20 are stacked on top of each other in the axial direction. Furthermore, by forming the drive unit 65 smaller than the second gear mechanism 20 when viewed from the second axial direction F2, the overall size of the device can also be reduced in the axial view.

[0090] Furthermore, in the steering unit 10 described above, the transmission mechanism 70 includes a relatively small-diameter drive pulley 75 attached to the drive shaft 67 of the drive device 65, a relatively large-diameter driven pulley 76 attached to the input shaft (second input shaft 45) of the second gear mechanism 20, and a transmission belt 77 wrapped around both pulleys 75 and 76. With this configuration, by connecting the drive unit 65 and the second gear mechanism 20 via a belt-type transmission mechanism 70, the effects of backlash are suppressed and operating accuracy is improved compared to using a gear-type transmission mechanism, and the distance between the drive unit 65 and the second gear mechanism 20 can be secured with a small number of parts.

[0091] Furthermore, in the steering unit 10 described above, the driven pulley support shaft 76a, which supports the driven pulley 76, also serves as the transmission output shaft 76b that transmits driving force to the second gear mechanism 20. With this configuration, by sharing the driven pulley support shaft 76a and the transmission output shaft 76b, the number of parts can be reduced, resulting in weight reduction and improved operating accuracy.

[0092] Furthermore, in the steering unit 10 described above, the second input gear 46 (transmission output gear) of the second gear mechanism 20 is integrally formed with the transmission output shaft 76b. With this configuration, the second input gear 46 of the second gear mechanism 20 is integrated with the transmission output shaft 76b, which also serves as the driven pulley support shaft 76a, thereby reducing the number of parts, making it lighter, and improving operating accuracy.

[0093] Furthermore, in the steering unit 10 described above, the transmission output shaft 76b includes a shaft portion 47 that extends beyond the second input gear 46 into the second gear mechanism 20 in the second axial direction F2, and this shaft portion 47 is supported inside the second gear mechanism 20 via a bearing 21d. In this configuration, the transmission output shaft 76b is supported by both the bearing 37d on the transmission mechanism 70 side and the bearing 21d on the second gear mechanism 20 side, by providing a shaft portion 47 at the tip of the transmission output shaft 76b that is supported within the second gear mechanism 20. This simplifies the bearing structure on the transmission mechanism 70 side and allows for miniaturization compared to the case where the transmission output shaft 76b is supported only by the bearing on the transmission mechanism 70 side.

[0094] Furthermore, the steering unit 10 includes a flange portion 37 that forms one side of the gear case 21 housing the reduction mechanism component 20d of the second gear mechanism 20 in the axial direction (second axial direction F2) of the output shaft (second output shaft 25) of the second gear mechanism 20, and a case portion 12 that housing the conversion mechanism component 11d of the first gear mechanism 11, with the flange portion 37 and the case portion 12 being integrally formed with each other. With this configuration, the flange portion 37 forming the second axial side +f2 of the gear case 21 of the second gear mechanism 20 and the case portion 12 of the first gear mechanism 11 are integrally formed with each other, thereby reducing the number of parts and making it lighter, as well as improving the accuracy of the relative position between the first gear mechanism 11 and the second gear mechanism 20 and improving the operating accuracy.

[0095] Furthermore, the steering unit 10 includes a plurality of fasteners B2 for fixing the case body (first case 22) of the gear case 21 of the second gear mechanism 20 to the flange portion 37, and a washer plate 39 having a size that includes the seating surfaces of at least two of the plurality of fasteners B2. In this configuration, the washer plate 39 for fastening the first case 22 of the second gear mechanism 20 to the flange portion 37 is provided in a size that spans the seating surfaces of multiple fasteners B2. Compared to the case where each fastener B2 has an individual washer, the washer plate 39 contacts the flange portion 37 even in the marginal area between each fastener B2. As a result, the surface pressure applied to the flange portion 37 by tightening each fastener B2 is reduced. Consequently, even when the flange portion 37 is formed from a light metal with low hardness, it is possible to ensure the tightening torque of each fastener B2 while suppressing deformation of the seating surface side of the flange portion 37, thereby improving reliability.

[0096] Furthermore, in the steering unit 10 described above, a controller 68 for controlling the drive of the drive unit 65 is positioned at one end of the drive unit 65 in the axial direction of the drive shaft 67 of the drive unit 65 (drive axis direction, second axis direction F2). The controller 68 has a flattened shape with reduced thickness in the drive axis direction, and its outer diameter is larger than that of the drive unit 65 when viewed from the drive axis direction. With this configuration, the controller 68, which is provided at the axial end of the drive unit 65, has a flattened shape with reduced thickness in the drive axial direction, and its outer diameter is larger than that of the drive unit 65 when viewed in the drive axial direction. This makes it possible to reduce the axial dimensions of the drive unit 65, including the controller 68, while ensuring the size of the controller 68 and thereby improving reliability.

[0097] Furthermore, in the steering unit 10 described above, the first gear mechanism 11 is positioned so that the first axial direction F1 of the first input shaft 13 intersects with the second axial direction F2 of the second gear mechanism 20, the first gear mechanism 11 and the second gear mechanism 20 are aligned in a third direction F3 that intersects the first axial direction F1 and the second axial direction F2, the flange portion 37 and the case portion 12 are formed symmetrically with respect to a plane S1 along the second axial direction F2 and the third direction F3, and the first gear mechanism 11 can be fitted with a conversion mechanism component 11d on the case portion 12 with the orientation of the first axial direction F1 reversed. According to this configuration, the flange portion 37 and the case portion 12 are formed symmetrically with respect to a plane S1 (a plane perpendicular to the first axis direction F1) that is aligned with the second axis direction F2 and the third direction F3, and the conversion mechanism component 11d of the first gear mechanism 11 can be attached to the case portion 12 with the orientation of the first axis direction F1 reversed, thereby enabling the steering unit 10 to be used for both right-hand drive and left-hand drive vehicles. In other words, when the steering unit 10 is mounted on both a right-hand drive vehicle and a left-hand drive vehicle, the arrangement of bulky parts such as the second gear mechanism 20 in the steering unit 10 is generally symmetrical between the right-hand drive and left-hand drive vehicles. Therefore, by making the first axial direction F1 (the direction that points up and down when mounted on a vehicle) of the first gear mechanism 11 connected to the steering shaft 3 reversible, and by making the flange portion 37 of the second gear mechanism 20 symmetrical with respect to a plane S1 perpendicular to the first axial direction F1, a symmetrical steering unit 10 can be obtained, making it possible to mount it on both right-hand drive and left-hand drive vehicles, thereby increasing the versatility of the steering unit 10 and reducing costs.

[0098] Furthermore, in the steering unit 10, the gear case 21 housing the reduction mechanism component 20d in the second gear mechanism 20 forms an oil chamber R1 housing the reduction mechanism component 20d, and the case portion 12 housing the conversion mechanism component 11d in the first gear mechanism 11 forms a separate space K2 separated from the oil chamber R1 of the second gear mechanism 20 via an oil seal 16c. With this configuration, the first gear mechanism 11, which receives input from the steering shaft 3, is lubricated with grease due to its low rotational speed. By separating the case portion 12 of the first gear mechanism 11 from the oil chamber R1 of the second gear mechanism 20, the total amount of oil in the device can be reduced, making it lighter, and friction caused by oil agitation can be reduced, improving operability. A sensor 19 for detecting steering torque and rotational speed is attached to the first gear mechanism 11. However, if the case portion 12 of the first gear mechanism 11 is connected to the oil chamber R1, it would be necessary to provide a dedicated oil seal for the sensor 19. In contrast, by separating the case portion 12 of the first gear mechanism 11 from the oil chamber R1 of the second gear mechanism 20, a simple oil seal can be used.

[0099] Furthermore, in the steering unit 10 described above, the drive unit 65 and the second gear mechanism 20 are connected via a belt-type transmission mechanism 70, and the transmission case 71 of the transmission mechanism 70 forms a second separation space K3 separated from the oil chamber R1 of the second gear mechanism 20 via a second oil seal (oil seal 45c and O-ring 37c1). With this configuration, by using a belt-type transmission mechanism 70 between the drive unit 65 and the second gear mechanism 20, the effects of backlash can be suppressed, the number of parts can be reduced, and weight and operating accuracy can be improved compared to using a gear-type transmission mechanism 70. By separating the case portion 12 of the transmission mechanism 70 from the oil chamber R1 of the second gear mechanism 20, the total amount of oil in the device can be reduced, resulting in a lighter weight, while friction caused by oil agitation can be reduced, improving operability. By making the transmission mechanism 70 oil-less, the number of oil seals on the drive unit 65 side can also be reduced.

[0100] Furthermore, in the steering unit 10 described above, the first output shaft 16 of the first gear mechanism 11 is positioned to avoid the second gear mechanism 20 when viewed from the second axial direction F2, and the tip of the first output shaft 16 is covered by a cover portion 72a attached to the case portion 12, and the cover portion 72a has a bulge portion 72c that bulges out toward the transmission mechanism 70 in the second axial direction F2. With this configuration, the cover portion 72a that covers the tip of the first output shaft 16 of the first gear mechanism 11 is provided with a bulge portion 72c that bulges out toward the transmission mechanism 70 in the second axial direction F2, thereby making it possible to form a space inside the cover portion 72a that communicates with the oil chamber R1 of the second gear mechanism 20. As a result, a space communicating with the oil chamber R1 can be formed at a position that avoids the second gear mechanism 20 when viewed from the second axial direction F2, thereby ensuring a sufficient ratio of space to the total volume of the oil chamber and improving reliability.

[0101] Figure 11 shows the steering unit 10 as viewed from the second axis direction F2, illustrating a modified arrangement of the drive unit 65. As shown in Figure 11, the steering unit 10 allows for easy repositioning of the drive unit 65 depending on the vehicle's layout space. Specifically, the drive unit 65 (and controller 68) can be positioned by moving it in the circumferential direction of the circular second gear mechanism 20 when viewed from the second axis direction F2.

[0102] Figure 12A is a perspective view showing a first modified configuration of the controller 68. Figure 12B is a perspective view showing a second modified configuration of the controller 68. The controller 68' shown in Figure 12A is positioned on the outer surface of the case cover 73 of the transmission case 71 of the transmission mechanism 70. The outer surface of the transmission case 71 can be easily made large, making it easier to provide multiple drive circuits on the controller 68. The controller 68'' shown in Figure 12B is divided into multiple (for example, two) sections and arranged around the outer circumference of the drive unit 65. Dividing the controller 68 into smaller sections is suitable when a large installation space cannot be secured.

[0103] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. Novel embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. Embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents. Among the embodiments disclosed herein, those composed of multiple objects may be integrated, and conversely, those composed of a single object may be divided into multiple objects. Whether or not they are integrated, the invention can be constructed in a way that achieves its objective. [Explanation of Symbols]

[0104] 1. Steering assist device 3. Steering shaft 10. Steering Unit (Steering Device) 11 First gear mechanism 11d Conversion mechanism component 12 Case section 13. Operation Input Axis (First Input Axis) 16 First output shaft 16c Oil seal (sealing component) 17 First output gear 19 sensors 20 Second gear mechanism 21 Gear Case 21d bearing 22. First Case 25 Second output shaft (output shaft) 37 Flange section 37c1 O-ring (second sealing component) 37d bearing 39 Washer Plate 45 Second input axis (input axis) 45c Oil seal (second sealing component) 46 Second input gear 47 Shaft 56 Transmission gears 56a Operating side transmission gear (primary input gear) 65 Drive unit 67 Drive shaft 68 Controller (control device) 70 Transmission mechanism 71 Transmission case 72a Cover section 72c bulge 73 Case Cover 75 Drive pulley (first pulley) 76 Driven pulley (second pulley) 76a Driven pulley support shaft (second pulley support shaft) 76b Transmission output shaft 76c transmission output gear 77 Power transmission belt A2,A3 external shape B2 Fastener F1 First axis direction F2 Second axis direction F3 Third direction H2 width K2 separation space K3 Second separation space R1 oil chamber S1 plane

Claims

1. It comprises a first gear mechanism that receives rotational input from handle operation and converts the direction of said rotation before outputting, and a second gear mechanism that receives primary rotation output from the first gear mechanism and reduces the primary rotation before outputting, The second gear mechanism comprises a flange portion that forms one side of the gear case housing the reduction mechanism components of the second gear mechanism in the axial direction of the output shaft, and a case portion that housing the conversion mechanism components of the first gear mechanism, A steering device in which the flange portion and the case portion are integrally formed with each other.

2. The steering device according to claim 1, further comprising a plurality of fasteners for fixing the case body of the gear case to the flange portion, and a washer plate having a size that includes the seating surfaces of at least two of the plurality of fasteners.

3. The device includes a drive unit that outputs a driving force to assist in the steering operation, A controller for controlling the drive of the drive device is positioned at one end of the drive device in the axial direction of the drive shaft of the drive device. The steering device according to claim 1 or 2, wherein the controller has a flattened shape with reduced axial thickness of the drive shaft, and its outer diameter is larger than that of the drive device when viewed from the axial direction of the drive shaft.

Images