Steering device

Abstract

A steering device (100) that steers a wheel about a kingpin, the steering device (100) being characterized by being provided with a hub (120) that rotatably supports the wheel (110), a knuckle arm (130) that steers the wheel (110), and a lower arm (150) that connects a vehicle body and the wheel (110), one end of the lower arm (150) is provided with a lower rotation guide part (170) capable of rotating around the main pin shaft, the lower rotation guide part (170) comprises an arc-shaped guide rail (302) with a constant curvature and a moving block (303) moving on the guide rail (302), and an imaginary plane including the guide rail (302) is orthogonal to the main pin shaft.

Description

Technical Field

[0001] The present invention relates to a steering device for steering wheels of a motor vehicle or the like. Background Art

[0002] Motor vehicles and the like use a steering device for steering wheels provided on the vehicle body. The wheels are steered around a kingpin axis, which is set to be inclined at a predetermined angle. Although steering performance is excellent when the distance between the position where the axis of the kingpin axis intersects the road surface and the center of the wheel's contact surface with respect to the road surface, i.e., the scrub radius, is set to be small, the joint portion of the upper arm and the joint portion of the lower arm of the existing steering device are composed of ball joints, and it is difficult to bring the kingpin axis close to the wheel to reduce the scrub radius.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 5-58127 Summary of the invention

[0006] Problems to be solved by the invention

[0007] As a technique for reducing the tire grinding radius, Patent Document 1 can be cited. Patent Document 1 constructs a kingpin shaft using a guide rail and can bring the kingpin shaft close to the wheel center, thereby reducing the tire grinding radius.

[0008] In recent years, electric vehicles with improved performance have become popular in response to environmental issues. In these vehicles, a so-called in-wheel motor is used, in which a motor is built into a wheel. There is a growing demand for a steering device that can reduce the tire wear radius.

[0009] Solutions to Solve Problems

[0010] The present invention has been completed in view of such problems, and its purpose is to provide a steering device that steers the wheels with a kingpin shaft as the center, and can improve driving stability by reducing the tire radius as much as possible, and can set the kingpin shaft to an appropriate angle corresponding to the suspension type, etc. by easily being able to change the kingpin inclination angle and caster angle of the kingpin shaft.

[0011] That is, the present invention is a steering device that steers a wheel arranged on a vehicle body with a kingpin axis as the center, the steering device comprising: a wheel hub that supports the wheel so as to be rotatable; a steering knuckle arm that is fixed to the wheel hub and steers the wheel; and a lower arm that connects the vehicle body and the wheel so as to be swingable, a lower rotating guide portion being provided at one end of the lower arm, the lower rotating guide portion connecting the wheel hub and the lower arm and being rotatable with the kingpin axis as the center, the lower rotating guide portion comprising a guide rail formed in a circular arc shape with a constant curvature and a moving block moving on the guide rail, an imaginary plane containing the guide rail being orthogonal to the kingpin axis.

[0012] Effects of the Invention

[0013] According to the steering device of the present invention, the kingpin shaft is constituted by the rotation center of the moving block of the lower rotating guide part, so the kingpin shaft can be buried in the wheel, and the tire wear radius can be reduced as much as possible. In addition, the virtual plane including the guide rail is orthogonal to the virtual kingpin shaft, so the kingpin inclination angle and the caster angle can be changed by changing the inclination angle of the virtual plane, that is, the installation posture of the guide rail relative to the wheel hub. Therefore, according to the steering device of the present invention, the tire wear radius can be reduced as much as possible, and the kingpin inclination angle and the caster angle can be easily changed by changing the installation posture of the guide rail. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a perspective view of a steering device according to a first embodiment of the present invention.

[0015] Figure 2 This is a diagram showing a state where the steering device according to the first embodiment of the present invention is viewed from the rear of the vehicle body.

[0016] Figure 3 It is a perspective view showing a lower rotation guide portion according to the first embodiment of the present invention.

[0017] Figure 4 This is a diagram showing a state where the steering device according to the first embodiment of the present invention is viewed from below.

[0018] Figure 5 It is a diagram showing a state where the steering device according to the first embodiment of the present invention is viewed from the axle direction.

[0019] Figure 6 It is a perspective view of a steering device according to a second embodiment of the present invention.

[0020] Figure 7 This is a diagram showing a state where a steering device according to a second embodiment of the present invention is viewed from above.

[0021] Figure 8This is a diagram showing a state where a steering device according to a second embodiment of the present invention is viewed from the rear of a vehicle body. DETAILED DESCRIPTION

[0022] Hereinafter, the steering device of the present invention will be described in detail with reference to the drawings.

[0023] Figure 1 1 is a perspective view of a steering device 100 according to a first embodiment of the present invention. The steering device 100 is used to steer wheels of a motor vehicle or the like. By using the steering device 100, the traveling direction of the vehicle body of the motor vehicle or the like can be controlled.

[0024] The steering device 100 includes a hub 120 disposed in a wheel 110 provided on a vehicle body (not shown) and supporting the wheel 110 so as to be rotatable; a knuckle arm 130 for steering the wheel 110; an upper arm 140 and a lower arm 150 for connecting the vehicle body and the wheel 110; an upper rotation guide 160 for supporting the wheel 110 so as to be steerable relative to the upper arm 140; and a lower rotation guide 170 for supporting the wheel 110 so as to be steerable relative to the lower arm 150. It should be noted that in the steering device 100 of the first embodiment, a double wishbone suspension device in which the upper arm 140 and the lower arm 150 are arranged in a vertical direction is described as an example, but the present invention is not limited thereto, and a strut suspension device in which the wheel 110 is suspended by a shock absorber 180 and the lower arm 150 may be used, and the suspension method may be changed appropriately. In addition, in the case of a strut type suspension device, the upper arm 140 and the upper rotation guide portion 160 are of course not included in the structure of the steering device 100 .

[0025] The knuckle arm 130 is fixed to the wheel hub 120. A joint portion 131 as a part of the knuckle arm 130 is offset relative to the axle of the wheel 110. A tie rod 132 is rotatably connected to the joint portion 131. Thus, the knuckle arm 130 is supported to be rotatable relative to the tie rod 132, and the steering operation transmitted from the tie rod 132 can be transmitted to the wheel 110.

[0026] The upper arm 140 has a bent portion 141 at one end and is formed into a substantially V-shape in a plan view. One end of the upper arm 140 is connected to a bracket 121 extending from the hub 120 to the upper part of the wheel 110, and the other end of the upper arm 140 is connected to the vehicle body. Thus, the vehicle body and the wheel 110 are relatively movable up and down.

[0027] like Figure 1 as well as Figure 2As shown, the upper arm 140 and the bracket 121 are connected via an upper rotation guide 160. The upper rotation guide 160 is fixed to the wheel 110 via the bracket 121. The upper rotation guide 160 is provided at a position above the axle of the wheel 110 and is composed of a ball joint. Therefore, the upper arm 140 is connected to the bracket 121 fixed to the hub 120 in the wheel 110 so as to be swingable. In addition, the bracket 121 is rotatable relative to the upper arm 140 around the axis of the upper rotation guide 160. Thus, the wheel 110 can turn relative to the upper arm 140 with the upper rotation guide 160 as the rotation axis.

[0028] like Figure 2 As shown in FIG. 1 , the lower rotation guide 170 is provided on the mounting surface 122, and the mounting surface 122 is provided on the wheel hub 120. That is, the lower rotation guide 170 is fixed to the wheel 110 via the wheel hub 120. The mounting surface 122 is provided on a plane slightly inclined relative to the wheel hub 120. The lower rotation guide 170 is provided at a position lower than the axle of the wheel 110. Figure 3 As shown in the figure, the lower rotation guide 170 includes a guide rail 302 having a plurality of rolling surfaces 301 formed along the length direction for rolling bodies 300 such as balls to roll, and a moving block 303 that moves freely along the length direction of the guide rail 302. Two rolling surfaces 301 are provided on the side surfaces of the guide rail 302, and a total of four rolling surfaces 301 are formed in the entire guide rail 302.

[0029] The moving block 303 is assembled to the guide rail 302 via a plurality of rolling elements 300. The guide rail 302 is formed in an arc shape with a constant curvature, and the guide rail 302 is fixed to the mounting surface 122. Therefore, the mounting surface 122 is equivalent to a virtual plane including the guide rail 302, and the mounting posture of the guide rail 302 relative to the wheel hub 120 is determined by the inclination angle of the mounting surface 122.

[0030] The moving block 303 includes a block body 304 and a pair of covers 305 fixed to both end surfaces of the block body 304 in the moving direction. Four load rolling surfaces (not shown) are formed on the block body 304, and these load rolling surfaces are arranged at positions opposite to the rolling surface 301 of the guide rail 302. By the load rolling surface and the rolling surface 301 being opposite to each other, a load passage is completed for the rolling element 300 to roll while carrying a load between the guide rail 302 and the block body 304. In addition, the block body 304 has four ball return passages (not shown) arranged substantially parallel to each load rolling surface, and the rolling element 300 rolls in the ball return passage in a state of being free from the load.

[0031] On the other hand, the cover body 305 is provided with a direction conversion path (not shown) connecting the load passage and the ball return passage, so that the rolling element 300 can travel back and forth between the load passage and the ball return passage. Therefore, when a pair of cover bodies 305 are fixed to the front and rear of the moving direction of the block body 304, the ends of the load passage and the ball return passage are connected to each other by the direction conversion path of the cover body 305, and the infinite circulation path of the rolling element 300 is completed in the moving block 303. Thus, the guide rail 302 and the moving block 303 can move relative to each other. It should be noted that in the example shown in this embodiment, the moving block 305 has four infinite circulation paths, but the number of the infinite circulation paths can be appropriately designed and changed. In addition, the lower rotating guide part 170 is described as a rolling guide device for the moving block 303 to move on the guide rail 302 via a plurality of rolling elements 300, but it is not limited to this. For example, it can also be a sliding guide device for the moving block 303 to move by sliding contact relative to the guide rail 302.

[0032] Figure 4 1 is a diagram showing a state of the steering device 100 as viewed from below. The lower arm 150 is formed into a generally A-shape in a plan view, the width of which gradually widens from one end 151. One end 151 of the lower arm 150 is connected to the moving block 303 of the lower rotating guide portion 170, and on the other hand, the other end 152 of the lower arm 150 is connected to the vehicle body. That is, the lower arm 150 is connected to the wheel 110 via the lower rotating guide portion 170 fixed to the wheel hub 120. One end 151 is fixed to a fixing portion 306 installed on the moving block 303. A portion facing the fixing portion 306 is provided. Figure 4 The through hole (not shown) in the vertical direction of the paper is provided, and the one end portion 151 is connected to the moving block 303 via a pin inserted into the through hole. Thus, the lower arm 150 is supported to swing freely about the connecting portion connected to the moving block 303 as an axis, and the vehicle body and the wheel 110 can move up and down relatively freely.

[0033] In addition, the guide rail 302 and the moving block 303 are relatively movable, so that the wheel 110 can be turned relative to the lower arm 150 via the hub 120 fixed to the guide rail 302 by the guide rail 302 moving relative to the moving block 303 .

[0034] As described above, the wheel 110 is supported by the upper rotating guide part 160 so as to be able to turn relative to the upper arm 140, and on the other hand, is supported by the lower rotating guide part 170 so as to be able to turn relative to the lower arm 150. That is, the wheel 110 turns using the kingpin axis formed by connecting the rotation center of the upper rotating guide part 160 and the axis of the rotation center of the moving block 303 in the lower rotating guide part 170 as the rotation axis. Therefore, the rotation center of the moving block 303 overlaps with the kingpin axis. However, the kingpin axis of this embodiment is not composed of a physical pin, but is an imaginary kingpin axis (hereinafter referred to as a "imaginary kingpin axis") that connects the rotation centers of the upper rotating guide part 160 and the lower rotating guide part 170. The imaginary kingpin axis is Figure 2 as well as Figure 5 In the figure, it is indicated by a single dot-dashed line. Figure 2 As shown in FIG. 1 , the imaginary kingpin axis is inclined at a predetermined kingpin inclination angle α. Figure 5 As shown in FIG. 1 , the imaginary kingpin axis is inclined at a predetermined caster angle β.

[0035] Figure 5 1 is a diagram showing the state of the wheel 110 as viewed from the axle direction. Since one end of the imaginary kingpin axis is the rotation center of the moving block 303 moving on the guide rail 302, the imaginary plane including the guide rail 302 is orthogonal to the imaginary kingpin axis. Therefore, when the inclination of the imaginary plane, that is, the inclination angle of the mounting surface 122 relative to the wheel hub 120 is changed, the posture of the guide rail 302 is changed, and the kingpin inclination angle α (refer to Figure 2 ) and caster angle β (refer to Figure 5 ) is changed.

[0036] As described above, since one end of the imaginary kingpin shaft of the steering device 100 is the rotation center of the moving block 303 connected to the one end portion 151 of the lower arm 150, the imaginary kingpin shaft is embedded in the wheel 110 and set (refer to Figure 2 Therefore, the steering device 100 can minimize the distance between the intersection of the kingpin axis and the road surface and the center of the wheel contact surface with respect to the road surface ( Figure 2The tire wear radius is the distance from the imaginary kingpin axis (dashed line) to the wheel hub 120. Although it is difficult to reduce the tire wear radius in a solid wheel such as an in-wheel motor, the steering device 100 of the present invention can bury the imaginary kingpin axis in the wheel 110, so the tire wear radius can be reduced as much as possible even in a solid wheel. In addition, the imaginary plane including the guide rail 302 is orthogonal to the imaginary kingpin axis, so the kingpin inclination angle α and the caster angle β can be changed by changing the inclination angle of the imaginary plane, that is, the installation posture relative to the wheel hub 120. Therefore, the steering device 100 of the present invention can reduce the tire wear radius as much as possible regardless of the type of suspension method, and can easily change the kingpin inclination angle α and the caster angle β by changing the installation posture of the guide rail 302 relative to the wheel hub 120.

[0037] In addition, in the existing steering device (for example, Patent Document 1), one end of the upper arm is connected to the bracket assembled to be movable on the guide rail, and the other end of the upper arm is connected to the wheel, so when the wheel turns along with the steering, the direction of the upper arm changes together with the wheel. As a result, the apparent length of the upper arm when the wheel is viewed from the front or rear of the vehicle body during steering is shorter than the actual length of the upper arm, and the lateral displacement of the wheel contact point, that is, the amount of wear (scuff) change, becomes larger. In contrast, in the steering device 100 of the present invention, the guide rail 302 of the lower rotating guide portion 170 is provided on the wheel hub 120 that supports the rotation of the wheel 110, and one end 151 of the lower arm 150 is connected to a movable block that can move freely along the guide rail 302, and the other end 152 of the lower arm 150 is connected to the vehicle body. Therefore, the lower arm 150 is configured not to be affected by the steering of the wheel. As Figure 4 As shown by the arrow X in FIG. 1 , the wheel 110 and the lower arm 150 are turned separately, so the direction of the lower arm 150 does not change together with the wheel 110 in the steering device 100. Therefore, in the steering device 100, the apparent length of the lower arm 150 when the wheel is viewed from the front or rear of the vehicle body during turning does not change, and the apparent length of the lower arm 150 during turning does not change relative to the actual length of the lower arm 150, so the amount of change due to wear can be reduced compared with the existing steering device. Therefore, the steering device 100 can improve the driving stability during turning compared with the existing steering device.

[0038] Figure 61 is a perspective view showing a steering device 100 according to a second embodiment of the present invention. The steering device 100 according to the second embodiment is different from the steering device according to the first embodiment in the structure of the upper rotating guide part 160. Therefore, with respect to the second embodiment, a detailed description of the structure other than the upper rotating guide part 160 is omitted. The upper rotating guide part 160 is fixed to a hub 120 that supports the wheel 110 so as to be rotatable, and includes a guide rail 161 for rolling bodies such as balls to roll along the length direction, and a moving block 162 that moves freely along the length direction of the guide rail 161. That is, the upper rotating guide part 160 of the second embodiment is constructed in the same manner as the lower rotating guide part 170 of the first embodiment, and the guide rail 161 and the moving block 162 can move relatively.

[0039] Figure 7 1 is a diagram showing a state of the steering device 100 as viewed from above. The bent portion 141, which is one end of the upper arm 140, is connected to the moving block 162, and on the other hand, the other end of the upper arm 140 is connected to the vehicle body. Therefore, the upper arm 140 is connected to the hub 120 in the wheel 110 via the upper rotation guide 160. Similar to the lower arm 150 and the moving block 303 of the first embodiment, the upper arm 140 and the moving block 162 are connected via a pin inserted into a through hole (not shown) of a fixed portion (not shown) installed on the moving block 162. As a result, the upper arm 140 is supported to swing freely with the connecting portion connected to the moving block 162 as an axis, and the vehicle body and the wheel 110 are relatively movable up and down.

[0040] In addition, the guide rail 161 and the moving block 162 are relatively movable, so that the wheel 110 can be turned relative to the upper arm 140 via the hub 120 fixed to the guide rail 161 by the guide rail 161 moving relative to the moving block 162 .

[0041] like Figure 8 As shown by the single-dot chain line, the imaginary kingpin axis of the steering device 100 is an axis formed by connecting the rotation center of the moving block 162 connected to the bent portion 141 of the upper arm 140 and the rotation center of the moving block 303 connected to the one end 151 of the lower arm 150. Therefore, the upper and lower rotation centers of the imaginary kingpin axis of the steering device 100 are both buried and set inside the wheel 110. The imaginary kingpin axis can be adjusted by changing the installation posture of the guide rail 161 of the upper rotating guide part 160 and the guide rail 302 of the lower rotating guide part 170 relative to the wheel hub 120. Therefore, the steering device 100 of the second embodiment can perform more precise adjustment of the kingpin inclination angle and the caster angle compared with the steering device of the first embodiment.

Claims

1. A steering device (100) for steering a wheel (110) provided on a vehicle body with a kingpin axis as the center. The steering device (100) is characterized by comprising: a wheel hub (120) which supports the wheel (110) so as to be rotatable; a steering knuckle arm (130) fixed to the wheel hub (120) and enabling the wheel (110) to steer; and a lower arm (150) which connects the vehicle body and the wheel (110) so as to be swingable, A lower rotation guide (170) is provided at one end of the lower arm (150), the lower rotation guide (170) connecting the wheel hub (120) and the lower arm (150) and being rotatable around the kingpin axis. The lower rotation guide (170) includes a guide rail (302) formed in a circular arc shape with a constant curvature, and a moving block (303) moving on the guide rail (302). An imaginary plane including the guide rail (302) is orthogonal to the kingpin axis.

2. The steering device (100) according to claim 1, characterized in that: The lower rotation guide portion (170) is fixed to the wheel hub (120). The vehicle body is connected to the other end of the lower arm (150).

3. The steering device (100) according to claim 1 or 2, characterized in that: The steering device (100) further includes an upper arm (140) that connects the vehicle body and the wheel (110) in a swingable manner. An upper rotation guide (160) is provided at one end of the upper arm (140), the upper rotation guide (160) connecting the wheel hub (120) and the upper arm (140) and being rotatable around the kingpin axis.

4. The steering device (100) according to claim 3, characterized in that The vehicle body is connected to the other end of the upper arm (140).

5. The steering device (100) according to claim 2, characterized in that: One end of the lower arm (150) is connected to a moving block (303) of the lower rotation guide (170).

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