Wheel module

Abstract

A wheel module (10) of the present application is used for a vehicle (90) including two or more independent steering wheels capable of being independently steered, and constitutes an independent steering wheel. The wheel module (10) is provided with a tire (2), a steering section (3) that outputs a steering force that steers the tire (2), a drive section (5) that outputs a drive force that drives the tire (2), a brake section (6) that outputs a braking force that brakes the tire (2), and a suspension mechanism (7). The suspension mechanism (7) is supported by an upper end side fulcrum (SU) and a lower end side fulcrum (SL), and cushions vibrations or impacts transmitted from a road surface. A virtual straight line in a celestial direction that passes through a center in a radial direction of the tire (2) and a center in a width direction is defined as a "tire center axis (Zt)". When viewed from a side surface of the tire (2), the lower end side fulcrum (SL) of the suspension mechanism (7) is disposed at a position away from the tire center axis (Zt).

Description

[0001] Cross-references to related applications

[0002] This application is based on Japanese Patent Application No. 2021-055592, filed on March 29, 2021, the contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to wheel modules. Background Technology

[0004] Previously, there was a known technology concerning a damping device for improving the buffering of vibrations and impacts transmitted from the tires to the sides of the vehicle body in a vehicle that includes independently steerable steering wheels. For example, the problem with the steering control device of the in-wheel motor vehicle disclosed in Patent Document 1 is that even with the addition of dampers, it avoids unnecessary large-scale additions and transmits a sufficiently large rotational torque.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2012-106524

[0006] In the steering control device of Patent Document 1, the outer shaft housing the buffer device is understood to be disposed on the central shaft of the in-wheel motor unit. That is, when viewed from the wheel side, the spring of the buffer device is vertically disposed on the central shaft of the tire in the vertical direction. Therefore, impacts from the road surface are directly transmitted to the spring, deteriorating ride comfort. Summary of the Invention

[0007] The purpose of this disclosure is to provide a wheel module that improves ride comfort in a wheel module comprising an independent steering wheel of a vehicle.

[0008] The wheel module disclosed herein is used in vehicles comprising two or more independently steerable steering wheels, and constitutes an independent steering wheel system. The wheel module includes tires, a steering unit, a drive unit, a braking unit, and a suspension mechanism.

[0009] The surface of a tire with its outer sidewall is defined as the sidewall, and the tread facing forward of the vehicle is defined as the front surface. The steering unit outputs a steering force to steer the tire. The drive unit outputs a driving force to drive the tire. The braking unit outputs a braking force to brake the tire. The suspension system is supported by upper and lower side pivots and dampens vibrations or impacts transmitted from the road surface.

[0010] The tire center axis is defined as a virtual straight line passing through the radial center and the width center of the tire in both the vertical and horizontal directions. When viewed from the side of the tire, the lower side pivot of the suspension is positioned away from the tire center axis.

[0011] As a result, impacts from the road surface are less likely to be directly transmitted to the spring. Therefore, it can suppress unpleasant vibrations caused by vertical disturbances from road surfaces such as steps and stones, thus improving ride comfort.

[0012] Preferably, when viewed from the side of the tire, the suspension mechanism is tilted relative to the tire's central axis. Attached Figure Description

[0013] The above-mentioned and other objects, features, and advantages of this disclosure will become more apparent from the accompanying drawings and from the following detailed description. The drawings are described below.

[0014] Figure 1 This is a top view of an independently steering vehicle using a wheel module according to one embodiment.

[0015] Figure 2 yes Figure 1 Side view of an independently steering vehicle.

[0016] Figure 3 This is a perspective view of a wheel module according to one embodiment.

[0017] Figure 4 yes Figure 3 IV-direction arrow view (viewed from the inside of the tire).

[0018] Figure 5 yes Figure 3 V-shaped arrow view (viewed from the front surface of the tire).

[0019] Figure 6 yes Figure 3 The VI directional arrow view.

[0020] Figure 7 This is a diagram showing the structure of a multi-winding motor in a steering motor.

[0021] Figure 8 This diagram illustrates the rotational motion centered on the arm connection axis.

[0022] Figure 9 This is a schematic diagram illustrating the compression action of the suspension mechanism when rotating upwards.

[0023] Figure 10 This is a schematic diagram illustrating the extension action of the suspension mechanism when rotating downwards. Detailed Implementation

[0024] A wheel module according to one embodiment will be described based on the accompanying drawings. The wheel module of this disclosure is used in vehicles comprising two or more independently steerable wheels, forming an independent steering wheel configuration. In one embodiment, a structural example of using four wheel modules in a four-wheeled vehicle where all wheels are independently steerable wheels is shown. Furthermore, in one embodiment, the steering and braking actuation commands will be described assuming manual driving by the driver.

[0025] (One implementation method)

[0026] exist Figure 1 The image schematically illustrates the configuration of the body 99 and four wheels 91, 92, 93, and 94 of a four-wheel independent steering vehicle 90, viewed from above. The four wheels are the left front wheel 91, right front wheel 92, left rear wheel 93, and right rear wheel 94. Each wheel 91-94 is an independently steerable wheel, consisting of wheel modules 10. The center point of each wheel module 10 represents the tire center axis Zt. A detailed definition of the tire center axis Zt will be described later.

[0027] exist Figure 2 The diagram schematically shows the state of the front wheel 92 and the rear wheel 94 as viewed from the right side of vehicle 90. Figure 2 In this designation, the wheel module used for the front wheel 92 is designated as "10F", while the wheel module used for the rear wheel 94 is designated as "10R" for distinction. The wheel modules 10F and 10R used for the left wheel also constitute independent steering wheels in the front wheels 91 and 92 and the rear wheels 93 and 94 of the vehicle 90.

[0028] The detailed structures of wheel modules 10F and 10R will be described later, but in terms of appearance, wheel module 10F for the front wheel 92 and wheel module 10R for the rear wheel 94 are symmetrical in the longitudinal direction with respect to the tire center axis Zt. That is, in wheel module 10F for the front wheel 92, the suspension mechanism 7 is positioned at the front of the vehicle 90 with respect to the tire center axis Zt. In wheel module 10R for the rear wheel 94, the suspension mechanism 7 is positioned at the rear of the vehicle 90 with respect to the tire center axis Zt.

[0029] The upper end of the suspension mechanism 7 is close to the tire's central axis Zt, while the lower end is inclined away from the tire's central axis Zt. Therefore, the suspension mechanisms 7 of the front and rear wheels 92 and 94 are configured with increasing spacing from top to bottom.

[0030] Compared to a conventional vehicle where the left and right wheels are connected by a rack and pinion, a vehicle where each wheel can steer independently has a larger interior space because it does not require the space of a rack and pinion. In addition, because it can perform "rotation on the spot" and "lateral movement" that are not possible in conventional vehicles, it increases the degree of freedom of movement when entering narrow roads, turning, or parking in confined spaces.

[0031] In independently steering vehicles, each steering wheel is configured as a wheel module that includes a steering mechanism, an in-wheel motor as a drive mechanism, and an electric brake as a braking mechanism. Depending on the structure of the wheel module, the effective space inside the passenger compartment may be narrowed, or the ride comfort may be deteriorated due to the increase in unsprung weight.

[0032] Therefore, in this embodiment, a wheel module is provided primarily for improving passenger comfort, and also facilitates increased cabin space and improved interference resistance. (See reference...) Figure 2 As described above, the basic structure of the wheel module 10F for the front wheels and the wheel module 10R for the rear wheels is the same for both individual steering wheels, except that they are symmetrical about the tire center axis Zt. Hereinafter, the wheel module 10 will be described as a single example without distinguishing between the front and rear wheels.

[0033] exist Figures 3-6 The diagram shows the structure of a wheel module 10 according to one embodiment. Hereinafter, the surface of the tire 2 having the outer tire sidewall 24 will be defined as the sidewall, and the tread 25 facing the front of the vehicle will be defined as the front surface. For example... Figure 4 Observing the composition from the inside Figure 1 The diagram shows the wheel module 10 of the left front wheel 91.

[0034] Define the three-dimensional axes of tire 2 as follows: the left-right direction of the vehicle when traveling straight is defined as the X direction, the front-back direction as the Y direction, and the height direction as the Z direction. Define the wheel axle Xt as the virtual straight line passing through the radial center of tire 2. Define the front and rear axles Yt as the virtual straight line passing through the radial center of tire 2 and along the horizontal direction of the vehicle's front-back. Define the tire center axis Zt as the virtual straight line passing through the radial center and the center of the width direction of tire 2 in the vertical direction.

[0035] The wheel module 10 includes a tire 2, a steering unit 3, an arm 4, a drive unit 5, a braking unit 6, and a suspension mechanism 7.

[0036] The steering unit 3 outputs a steering force to steer the tire 2 based on the driver's steering wheel operation, etc. The steering unit 3 includes a steering motor 31 that outputs torque, and a reducer 32 that reduces the rotation of the steering motor 31 and transmits it to the arm 4. The steering motor 31 and the reducer 32 are stacked on the tire central axis Zt. The steering unit 3 is miniaturized by increasing the reduction ratio of the reducer 32.

[0037] For example, Figure 7As shown, the steering motor 31 in one embodiment is a dual-winding motor with redundant two sets of three-phase windings 311 and 312. Therefore, even if an abnormality occurs in one winding set or its corresponding drive circuit, power can still be supplied to the other winding set, thus improving reliability.

[0038] Arm 4 connects the steering unit 3 and the tire 2. The steering force output from the steering unit 3 is transmitted to the tire 2 via arm 4. Arm 4 includes an upper arm 41 on the side of the steering unit 3 and a rocker arm 45 on the side of the tire 2.

[0039] The upper arm 41 includes a top plate portion 42, a main body portion 43, and a top plate extension portion 44. The top plate portion 42 is disposed on the tire central axis Zt directly above the tire 2 and connected to the steering portion 3. The main body portion 43 is located on one side of the tire central axis Zt. Figure 4 The left side of the suspension mechanism 7 extends from the upper part of the tire 2 to below the front and rear axles Yt. The top plate extension 44 extends from the top plate part 42 in the opposite direction to the main body part 43, supporting the upper side pivot point SU of the suspension mechanism 7. The upper arm 41 and the rocker arm 45 are connected so that they can rotate about the horizontal arm connection axis Xa. Figure 4 As shown, when viewed from the side of tire 2, the arm connecting axis Xa is far from the tire center axis Zt.

[0040] The rocker arm 45 includes a connecting end 46 disposed around the arm connecting shaft Xa, a central portion 47 disposed around the wheel axle Xt, and a free end 48 disposed on the opposite side of the connecting end 46 relative to the central portion 47. The free end 48 supports the lower end pivot SL of the suspension mechanism 7.

[0041] The drive unit 5 consists of an in-wheel motor, which outputs driving force to drive the tires 2 according to the driver's acceleration operation, etc. The braking unit 6 consists of an electric or hydraulic brake, which outputs braking force to brake the tires 2 according to the driver's braking operation, etc.

[0042] The suspension mechanism 7 is supported by the upper side pivot SU and the lower side pivot SL, and buffers vibrations or impacts transmitted from the road surface. The suspension mechanism 7 includes a damper 71 as a rod-shaped buffer member and a helical spring 72 inserted into the damper 71. The central axis of the damper 71 and the spring 72 is defined as the suspension mechanism axis YZs. The symbol "YZs" means that it is an axis parallel to the YZ plane containing the front and rear axles Yt of the tire 2 and the tire center axis Zt.

[0043] like Figure 4 As shown, approximately 70% of the length of the suspension mechanism 7 is positioned inside the radial outer edge of the tire 2. For example, in Japanese Patent Application Publication No. 2019-182336... Figure 2In the disclosed steering control device, since the suspension mechanism is located outside the radial outer edge of the tire, the axle length is relatively long, resulting in a reduction in passenger compartment space. In contrast, in this embodiment, most of the axle length of the suspension mechanism 7 is located inside the radial outer edge of the tire 2, thus increasing the passenger compartment space.

[0044] like Figure 4 As shown, when viewed from the side of tire 2, the lower end support point SL of suspension mechanism 7 is positioned away from the tire's central axis Zt. Furthermore, the suspension mechanism axis YZs is inclined relative to the tire's central axis Zt.

[0045] For example, in the steering control device disclosed in Patent Document 1 (Japanese Patent Application Publication No. 2012-106524), since the spring of the buffer device is vertically arranged on the central axis of the tire in the vertical direction, the impact from the road surface is directly transmitted to the spring, which deteriorates the ride comfort. In contrast, in this embodiment, by tilting the suspension mechanism 7 away from the tire central axis Zt, the impact from the road surface is less likely to be directly transmitted to the spring 72. Therefore, it is possible to suppress the generation of unpleasant vibrations caused by vertical interference from road surface differences, stones, etc., and improve ride comfort.

[0046] The upper side pivot SU of the suspension mechanism 7 is supported by the top plate extension 44 of the upper arm 41 and is rotatable. Furthermore, the lower side pivot SL is supported by the free end 48 of the rocker arm 45 and is rotatable. The lower side pivot SL of the suspension mechanism 7 can rotate about the arm connecting axis Xa in a plane parallel to the side surface of the tire 2. Figure 4 In the initial state shown, the wheel axle Xt and the lower side support SL are at the same height and are positioned higher than the arm connecting axle Xa.

[0047] Here, refer to Figures 8-10 The detailed description of the rotational motion centered on the arm connecting axis Xa is provided. Figure 8 The diagram shows tire 2 rotating upwards from its initial state (represented by solid lines) around the arm connection axis Xa, and then rotating downwards into a descending state. Additionally, in... Figure 8 For illustrative purposes, the rotation amount is shown as larger than the actual value. At this time, the wheel axle Xt moves along a circular arc of radius r1. When tire 2 is raised, this action pulls the vehicle body down; when tire 2 is lowered, this action lifts the vehicle body. Accompanying this, the lower end support point SL of the suspension mechanism 7 moves along a circular arc of radius r2.

[0048] exist Figure 9 , Figure 10The diagram schematically illustrates the positional relationship between the tire 2, upper arm 41, rocker arm 45, and suspension mechanism 7. The positions of the upper arm 41 and the upper end support portion SU of the suspension mechanism 7 remain unchanged. Figure 9 As shown, if tire 2 experiences an upward force from the road surface, and wheel axle Xt rotates upward, the position of the lower side support SL rises, and the spring 72 of the suspension mechanism 7 is compressed. Figure 10 As shown, if the tire 2 is subjected to a downward force from the road surface, the wheel axle Xt rotates downward, the position of the lower end support SL becomes lower, and the spring 72 of the suspension mechanism 7 extends.

[0049] In this way, the suspension mechanism 7, by rotating its lower end support point SL, supported by the rocker arm 45, around the arm connecting axis Xa according to the force exerted on the tire 2 from the road surface, dampens vibrations or impacts transmitted from the road surface. Since the lower end support point SL of the suspension mechanism 7 is positioned away from the tire's central axis Zt, the force directly transmitted from the road surface is attenuated and transmitted to the suspension mechanism 7 based on the ratio of the rotation radius r1 of the wheel axle Xt to the rotation radius r2 of the lower end support point SL. Therefore, as described above, it is possible to suppress unpleasant vibrations caused by road surface disturbances, thereby improving ride comfort.

[0050] Next, regarding steering maneuvers, such as Figure 5 As shown, when viewed from the front surface of tire 2, the kingpin axis Zk and the tire center axis Zt are aligned. Additionally, as... Figure 6 As shown, when tire 2 turns, the positional relationship between tire 2 and suspension mechanism 7 is maintained.

[0051] In the steering control device disclosed in Patent Document 1, the steering center of the tire, i.e., the kingpin, is offset from the central axis in the width direction of the tire. Therefore, there are concerns that interference from obstacles, step differences, etc., and torque steer during braking and driving may interfere with the "driving / turning / stopping" operation.

[0052] In contrast, in this embodiment, by aligning the kingpin Zk and the tire center axis Zt, the offset is reduced to zero, thereby reducing the torque directional change to zero. That is, as in... Figure 5 As indicated by the arrow in (*1), since there is no braking force affecting the actual steering torque, interference with "driving / turning / stopping" actions can be prevented. Furthermore, as indicated by the impact symbol in (*2), there is no interference from steps, stones, etc., affecting the actual steering torque. Therefore, interference resistance is improved.

[0053] (Other implementation methods)

[0054] (a) The independently steering vehicle using wheel module 10 is not limited to four-wheeled vehicles, but can also be a two-wheeled or three-wheeled vehicle. In two-wheeled and three-wheeled vehicles, it is preferable that in the wheel module 10F for the front wheels, the suspension mechanism 7 is positioned at the front of the vehicle relative to the tire center axis Zt, and in the wheel module 10R for the rear wheels, the suspension mechanism 7 is positioned at the rear of the vehicle relative to the tire center axis Zt. Furthermore, in the case of a four-wheeled vehicle, it is not limited to all wheels being independently steering wheels; for example, the left and right front wheels can be independently steering wheels, and the left and right rear wheels can be connected by a rack and pinion. Thus, any vehicle containing two or more independently steering wheels can be a vehicle that uses wheel module 10.

[0055] (b) The specific structures of the steering unit 3, drive unit 5, and braking unit 6 are not limited to the above embodiments, and can be any structure that achieves their respective functions. The steering motor 31 is not limited to a dual-winding motor, and can also be a multi-winding motor with redundantly having three or more winding groups. Alternatively, it can be a motor consisting of a single winding group.

[0056] (c) The arm 4 is not limited to the structure in which the upper arm 41 and the rocker arm 45 are connected, but can also be a structure in which the steering part 3 and the tire 2 are connected as one piece.

[0057] (d) The wheel module 10 can also be applied to autonomous vehicles. In this case, the phrase "according to the driver's operation" in the description of the steering unit 3, drive unit 5, and braking unit 6 in the above embodiment can be replaced with "according to the instructions of autonomous driving".

[0058] The present disclosure is not limited to such implementation methods and can be implemented in various ways without departing from its spirit.

[0059] This disclosure has been described in accordance with embodiments. However, this disclosure is not limited to these embodiments and structures. This disclosure also includes various modifications and equivalent variations. In addition, various combinations and methods, further including only one of their elements, or other combinations and methods with more or fewer elements, are also included in the scope and spirit of this disclosure.

Claims

1. A wheel module for use in a vehicle comprising two or more independently steerable steering wheels, and constituting the aforementioned independently steerable steering wheels, wherein the wheel module comprises: A tire, the sidewall of which has the outer sidewall is defined as the sidewall, and the tread facing the front of the vehicle is defined as the front surface. The steering unit outputs a steering force that turns the aforementioned tires. An arm connects the aforementioned steering unit and the aforementioned tire; The drive unit outputs the driving force that drives the aforementioned tires; The braking unit outputs braking force to brake the aforementioned tires; and The suspension mechanism includes a damper and a helical spring inserted into the damper. The damper is a rod-shaped buffer component. The suspension mechanism is supported by an upper side support and a lower side support, and buffers vibrations or impacts transmitted from the road surface. If a virtual straight line in the heaven and earth directions passing through the radial center and the width center of the tire is defined as the tire's central axis, then when viewed from the side of the tire, the lower end side pivot of the suspension mechanism is positioned away from the tire's central axis. The steering force output from the aforementioned steering unit is transmitted to the aforementioned tire via the aforementioned arm. The upper arm on the steering side of the aforementioned arm and the rocker arm on the tire side are connected so that they can rotate about a horizontal arm connection axis. When viewed from the side of the tire, the arm connection axis is located below the radial center of the tire and is located away from the tire center axis on the side opposite to the lower end pivot point of the suspension mechanism. The upper side support of the aforementioned suspension mechanism is supported by the upper arm to allow rotation, and the lower side support is supported by the rocker arm to allow rotation. The lower end support of the suspension mechanism is capable of rotating in a plane parallel to the side of the tire, with the arm connecting shaft as the center.

2. The wheel module according to claim 1, wherein, When viewed from the side of the tire, the suspension mechanism is tilted relative to the tire's central axis.

3. The wheel module according to claim 1 or 2, wherein, When the aforementioned tires are turning, the positional relationship between the aforementioned tires and the aforementioned suspension mechanism is maintained.

4. The wheel module according to claim 1 or 2, wherein, When viewed from the front surface of the tire, the kingpin is aligned with the tire's center axis.

5. The wheel module according to claim 1 or 2, wherein, The aforementioned steering unit includes a steering motor that outputs torque, and a reducer that slows down the rotation of the steering motor and transmits it to the aforementioned arm.

6. The wheel module according to claim 5, wherein, The aforementioned steering motor is composed of a multi-winding motor with redundant winding groups.

7. The wheel module according to claim 1 or 2, wherein, It refers to multiple wheel modules that constitute the aforementioned independent steering wheels in one or more front wheels and one or more rear wheels of a vehicle. The suspension mechanism of the front wheel module is positioned on the front side of the vehicle relative to the tire's central axis. The suspension mechanism of the rear wheel module is located on the rear side of the vehicle relative to the tire center axis.

8. The wheel module according to claim 1 or 2, wherein, The aforementioned rocker arm includes a connecting end disposed around the arm connecting shaft and a free end disposed on the side opposite to the connecting end. The aforementioned free end supports the aforementioned lower end side fulcrum of the aforementioned suspension mechanism.

9. The wheel module according to claim 1 or 2, wherein, In the initial state, the lower end support point is positioned higher than the arm connecting shaft.

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