CN101148176A - Variable wheel positioning vehicle - Google Patents

Abstract

A variable wheel positioning vehicle has a wheel position changing mechanism and a wheel position control device to change a wheel position of a wheel with respect to a center of gravity of a vehicle body. The wheel position changing mechanism is arranged to move a suspension device along a movement path with respect to the vehicle body and to hold the suspension device at any position along the movement path. The wheel position control device issues a movement command to the wheel position changing mechanism that changes a wheel positioning distance between a center rotation axis of one of the wheels and the center of gravity of the vehicle body as measured in a direction parallel to an acceleration direction of the center of gravity of the vehicle body based on a traveling condition the vehicle.

Description

Variable wheel alignment vehicle

The present application claims priority from Japanese patent application No.2006-256633 filed on 9/22/2006. The entire contents of Japanese patent application No.2006-256633 are incorporated herein by reference.

Technical Field

The present invention relates to vehicles with variable wheel alignment, i.e. vehicles in which the position of the wheels can be changed.

Background

Various vehicles or mobile robots have been proposed, which travel using articulated legs with conventional tires, thereby improving the behavior stability of the vehicle. In this type of vehicle, a variable wheel base is provided to achieve both convenience and behavior stability.An example of this type of vehicle is disclosed in "Tracking control of Mobile Robots with Redudada Multi-imaging vehicles", masahiro Toyoda, the Japan society of mechanical Engineers, journal of9 ^th Symposium on motion and simulation control, no.05-15, niigata, 8/month-23-25/2005 (see also link:http://www.cl.mes.musashi-tech.ac.jp/abstracts/kawamura.htm). The technique described in this first publication is very complex. Another example of this type of vehicle is disclosed in japanese laid-open patent publication No. 2005-231452. The technique described in this second publication can only change the wheel base.

In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved vehicle having a variable wheel alignment mechanism. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.

Disclosure of Invention

It has been found that the technique in the above-mentioned first-mentioned publication is difficult to apply to a practical vehicle, because the multi-jointed leg tends to make the structure large and complicated. Meanwhile, in the second-mentioned publication, this second technique can improve the convenience of the vehicle as compared with the technique of the first-mentioned publication, because it can change only the wheel base. However, the technology of the above-mentioned second-mentioned publication still has room for improvement in the stability of the behavior of the vehicle.

The present invention has been made in view of these problems. An object of the present invention is to provide a variable wheel alignment vehicle of a simple structure, which can improve both the convenience and the behavior stability of the vehicle and achieve a higher degree of freedom in the behavior of the vehicle.

In order to achieve the above object, a variable wheel alignment vehicle according to the present invention basically includes a vehicle body, a plurality of wheels, a suspension device, a steering mechanism, a drive device, a wheel position changing mechanism and a wheel position control device. The vehicle body has a center of gravity. The plurality of wheels are rotatably mounted with respect to the vehicle body. The suspension device is operatively disposed between the wheel and the vehicle body. The steering mechanism is operatively connected to the suspension device to change the orientation of at least one of the wheels relative to the vehicle body. The drive means is operatively connected to drive at least one of the wheels. The wheel position change mechanism is operatively connected to the suspension device to move the suspension device relative to the vehicle body along a path of travel and to maintain the suspension device at any position along the path of travel. The wheel position control device is operatively connected to the wheel position changing mechanism to issue a movement instruction to the wheel position changing mechanism to change a wheel alignment distance between a center rotational axis of one of the wheels and the center of gravity of the vehicle body, measured in a direction parallel to an acceleration direction of the center of gravity of the vehicle body, in accordance with a running condition of the vehicle.

These and other objects, features, aspects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses a preferred embodiment of the present invention.

Drawings

Referring now to the attached drawings which form a part of this original disclosure:

FIG. 1 (a) is a simplified side view of the appearance of a variable wheel alignment vehicle having a variable wheel geometry according to a first embodiment;

FIG. 1 (b) is a top plan view of the exterior of the variable wheel alignment vehicle shown in FIG. 1 (a) according to the first embodiment;

FIG. 2 is a schematic top plan view of a variable wheel alignment vehicle having a variable wheel geometry according to a first embodiment;

FIG. 3 (a) is a simplified side view (selected portions shown in cross-section) of a wheel mounting structure for a variable wheel alignment vehicle according to a first embodiment;

FIG. 3 (b) is a schematic top view of selected portions of the wheel mounting structure for the variable wheel alignment vehicle according to the first embodiment;

4 (a) to 4 (c) show different schemes of wheel and wheel base for a variable wheel alignment vehicle according to a first embodiment;

FIG. 5 is a graph of cornering ability versus wheel load during cornering;

fig. 6 shows the track and wheelbase positions of a vehicle employing a variable wheel geometry according to the first embodiment when the wheel loads of the four wheels are equally distributed;

FIG. 7 is a view showing the distance l for the variable wheel alignment vehicle according to the first embodiment when the height of the center of gravity is assumed to be 0.5 m ₁ And l ₂ An illustration of the range of motion of;

fig. 8 shows the track and wheel base positions of the variable wheel alignment vehicle according to the second embodiment when the wheel loads of the four wheels are freely distributed;

FIG. 9 illustrates the track and wheelbase positions of a variable wheel alignment vehicle according to a third embodiment when the wheel positions are controlled to achieve a desired vehicle attitude angle;

FIG. 10 is a graph showing the distance l in the variable wheel positioning vehicle according to the fourth embodiment when the reference wheel or reference wheels are held fixed and the other wheels are moved to obtain any desired wheel load distribution corresponding to the four wheels ₁ And l ₂ An illustration of the range of motion of;

fig. 11 shows a wheel arrangement used in the fourth embodiment during acceleration;

fig. 12 shows a wheel arrangement used in the fourth embodiment during deceleration;

fig. 13 shows a wheel arrangement used in the fourth embodiment during cornering;

fig. 14 shows a wheel arrangement used in the fourth embodiment when the vehicle decelerates and turns simultaneously;

fig. 15 is a graph showing an actuator load generated when wheels other than the reference wheel are moved according to the fourth embodiment;

fig. 16 shows a wheel moving path according to the fifth embodiment;

fig. 17 shows an example of how the center of gravity of the vehicle changes when the wheel moves along the wheel moving path according to the fifth embodiment;

fig. 18 shows another example of how the center of gravity of the vehicle changes when the wheel moves along the wheel moving path according to the fifth embodiment;

fig. 19 shows an example of a wheel moving path according to the fifth embodiment;

fig. 20 shows another example of the moving path of the wheel according to the fifth embodiment;

fig. 21 (a) is a simplified side view (selected portions shown in cross-section) of a wheel mounting structure for a variable wheel alignment vehicle according to a sixth embodiment;

FIG. 21 (b) is a simplified top view of selected portions shown of a wheel mounting structure for a variable wheel alignment vehicle according to a sixth embodiment;

fig. 22 (a) is a simplified side view (selected portions are shown in section) of a wheel mounting structure for a variable wheel alignment vehicle according to a seventh embodiment;

FIG. 22 (b) is a simplified top view of selected portions shown of a wheel mounting structure for a variable wheel alignment vehicle in accordance with a seventh embodiment;

fig. 23 (a) is a simplified side view (selected portions shown in cross-section) of a wheel mounting structure for a variable wheel alignment vehicle according to an eighth embodiment;

FIG. 23 (b) is a simplified top view of selected portions shown of a wheel mounting structure for a variable wheel alignment vehicle in accordance with an eighth embodiment;

fig. 24 (a) is a simplified side view (selected portions shown in section) of a wheel mounting structure for a variable wheel alignment vehicle according to a ninth embodiment;

fig. 24 (b) is a simplified top view of selected portions shown of a wheel mounting structure for a variable wheel alignment vehicle according to a ninth embodiment;

fig. 25 (a) is a simplified side view (selected portions shown in cross-section) of a wheel mounting structure for a variable wheel alignment vehicle according to a tenth embodiment;

FIG. 25 (b) is a simplified top view of selected portions shown of a wheel mounting structure for a variable wheel alignment vehicle in accordance with a tenth embodiment;

fig. 26 (a) is a simplified side view (selected portions are shown in section) of a wheel mounting structure for a variable wheel alignment vehicle according to an eleventh embodiment;

FIG. 26 (b) is a simplified top view of selected portions shown of a wheel mounting structure for a variable wheel alignment vehicle according to an eleventh embodiment;

FIG. 26 (c) is a schematic top view of a variable wheel positioning vehicle employing a variable wheel geometry according to an eleventh embodiment;

fig. 27 (a) is a simplified side view (selected portions shown in cross-section) of a wheel mounting structure for a variable wheel alignment vehicle according to a twelfth embodiment;

fig. 27 (b) is a schematic top plan view of a variable wheel positioning vehicle having a variable wheel geometry in accordance with a twelfth embodiment;

fig. 28 shows a wheel arrangement used in the first embodiment when the drive wheels are malfunctioning;

FIG. 29 is a schematic top view showing a variable wheel alignment vehicle employing a variable wheel geometry in accordance with a variation of the first embodiment;

FIG. 30 is a schematic top view showing a variable wheel alignment vehicle employing a variable wheel geometry in accordance with a variation of the first embodiment;

FIG. 31 is a schematic top view showing a variable wheel alignment vehicle employing a variable wheel geometry according to a variation of the first embodiment;

FIG. 32 is a series of schematic views of a variable wheel alignment vehicle illustrating an example of the operation of the first embodiment;

fig. 33 (a) - (f) are a series of schematic diagrams of various variable wheel alignment vehicles according to some alternative embodiments.

Detailed Description

Selected embodiments of the present invention will be described below with reference to the accompanying drawings. It will be apparent to those skilled in the art from this disclosure that the following descriptions of the embodiments of the present invention are provided for illustration only and not for the purpose of limiting the invention as defined by the appended claims.

Referring initially to fig. 1 (a) and 1 (b), there is shown a variable wheel alignment vehicle according to a first embodiment of the present invention. Fig. 1 (a) and 1 (b) show the appearance of a variable wheel alignment vehicle according to a first embodiment. The vehicle basically includes a vehicle body 100, a pair of non-driving wheel units 400 provided on a lower portion of the vehicle body 100, and a pair of driving wheel units 300 provided on a lower portion of the vehicle body 100. Hereinafter, the variable positioning of the wheel relative to the vehicle body is referred to as "variable wheel geometry".

Fig. 2 is a top plan view of a vehicle having a variable wheel geometry according to a first embodiment. The vehicle having the variable wheel geometry according to the first embodiment further includes a steering angle sensor 110, an accelerator position sensor 111, a brake sensor 112, an acceleration and yaw rate sensor (acceleration vector detecting means) 120, a pair of driving wheel units 300, a plurality of wheel unit position sensors 310 (one for each wheel), a plurality of steering angle sensors 320 (one for each wheel) for detecting a steering angle of the wheel, a pair of driving actuators 330, a plurality of steering actuators (wheel turning means) 340 (one for each wheel), a plurality of track and base changing actuators (wheel position changing means) 350 (one for each wheel), a pair of wheels 390, a pair of non-driving wheel units 400, and a controller (geometry controlling means) 500. In the vehicle having the variable wheel geometry according to the first embodiment, the non-driving wheel unit 400 is disposed as the left and right front wheels, and the driving wheel unit 300 is disposed as the left and right rear wheels.

The steering angle sensor 110 detects the amount by which the driver turns the steering wheel (steering angle). The throttle position sensor 111 detects the amount of throttle operation by the driver. The brake sensor 112 detects the amount of the driver operating the brake. The acceleration and yaw rate sensor 120 detects the acceleration and yaw rate of the vehicle. Each wheel unit position sensor 310 detects the position of the corresponding driven wheel unit 300 or non-driven wheel unit 400 along the wheel unit moving path 200. Each steering angle sensor 320 detects the steering angle of the corresponding wheel 390 (i.e., the steering angle of the wheel 390 with respect to the forward direction of the vehicle).

A corresponding drive actuator 330 is provided on each drive wheel unit 300 and is used to drive a corresponding wheel 390. For example, a hub motor may be used as the driving actuator 330.

The steering actuator 340 is provided on the driving wheel unit 300 and the non-driving wheel unit 400 and serves to change the steering angle of the corresponding wheel 390. For example, an electric motor may be used as the steering actuator 340.

Each track and wheel base changing actuator 350 serves to move the corresponding driven wheel unit 300 or non-driven wheel unit 400 along the wheel unit moving path 200. The track and wheel base changing actuators 350 are controlled by the controller 500. The wheel unit moving path 200 is arranged in a horizontal circle centered on the center of gravity of the vehicle such that the wheels 390 move along a single circular moving path centered on the center of gravity. The structure for realizing the wheel unit moving path 200 will be described below.

The controller 500 drives the driving actuator 350 according to the accelerator pedal position and the vehicle speed, thereby controlling the vehicle speed. The controller 500 also drives the steering actuator 340 according to signals of the steering angle sensor 110 and the acceleration and yaw rate sensor 120, thereby controlling the direction in which the vehicle travels.

The controller 500 also drives the track and wheelbase changing actuator 350 to change the wheel positions and obtain a target track, a target wheelbase, and a target wheel load corresponding to each wheel, based on signals of the vehicle speed and steering angle sensor 110, the accelerator position sensor 111, the brake sensor 112, the acceleration and yaw rate sensor 120, and the wheel unit position sensor 310. These target values are determined according to the running condition or the running state of the vehicle.

Referring to fig. 3 (a) and 3 (b), each wheel 390 is connected to the vehicle body 100 through a suspension frame 600. The suspension frame 600 is mounted to the bottom surface of the vehicle body 100 (or the bottom surface of another suspension frame) using a bearing 610. The linear motor and slider device 615 is provided in a ring shape along the middle of the side of the vehicle body 100. Thus, the suspension frame 600 is supported rotatably with respect to the vehicle body 100. The linear motor and slider device 615 of the first embodiment corresponds to the track and wheel base changing actuator 350 shown in fig. 2 and is used to move the wheel 390 with respect to the vehicle body 100 using the horizontal steering driving power of the linear motor.

The steering shaft of each wheel 390 is supported on the suspension frame 600 using a rod 620 and a bearing 630 disposed at the middle of the rod 620. The upper end of the rod 620 is supported on a suspension arm 650 using a ball joint 640. The suspension arm 650 is arranged such that it can pivot in the vertical direction with respect to the suspension frame 600. A steering device 660 is connected to each rod 620. The wheels 390 are steered by driving a steering actuator 340 fixed to the suspension frame 600.

Fig. 4 (a), 4 (b) and 4 (c) show the resulting wheel geometry when the wheel 390 is moved to obtain different wheelbases. As shown in fig. 4, the track and wheel base changing actuator (vehicle) shown in fig. 2 and 3Wheel alignment changing device) 350 is used to move the wheel 390. Thus, the track and wheel base changing actuator 350 changes the wheel base of a vehicle having a variable wheel geometry, which may be reduced to a minimum value/ _α X 2 or increase to l _c ×2。

Thus, when a vehicle employing a variable wheel geometry according to the first embodiment travels on a city street, for example, at a relatively low speed or is parked in a garage at a very low speed, a smaller turning radius can be obtained by reducing the wheelbase. Meanwhile, when the vehicle travels at a high or medium speed or on a winding road, the driving stability can be obtained by increasing the wheel base. These wheel alignment moving operations may be selected automatically according to the vehicle speed or other parameters or by using an operation performed by the driver.

The wheel position movement control performed according to the wheel load in the first embodiment will now be described. This control is mainly used when the vehicle is normally running except for running on city streets and parking in a garage as described above. More specifically, the control is used when the vehicle requires running stability and improves the running stability by moving the wheels according to the wheel load instead of simply changing the track and the wheel base.

The effect of the moving wheel load on the driving behavior of the vehicle will now be explained with reference to fig. 5. The graph of fig. 5 shows a plot of cornering capacity Cp against wheel load during cornering. The solid line curve shows the cornering ability Cp of the wheels of different predetermined specification vehicles obtained when the wheel load moves during cornering. Since cornering ability depends largely on the ratio of tire section height to width, fig. 5 shows a graph with a ratio of tire section height to width of 60 (60 series), a ratio of tire section height to width of 70 (70 series), and a ratio of tire section height to width of 82 (82 series). 1. Generally, the cornering ability Cp is larger when the ratio of the tire section height to the width is smaller, and is smaller when the ratio of the tire section height to the width is larger. Conversely, when the ratio of the tire section height to the width is large, the fuel efficiency improves.

According to the curve of cornering ability Cp against wheel load in fig. 5 corresponding to a tire section height-to-width ratio of 70, the wheel load of each wheel when the vehicle is not subjected to cornering acceleration there is 3.9kN. When the turning acceleration is, for example, 0.3G, the wheel load of the wheel on the turning outer side increases to 5.5kN, and the wheel load of the wheel on the turning inner side decreases to 2.3kN due to the load shift. When this occurs, the cornering ability of the wheels on the cornering outer side increases due to an increase in the wheel load, and the cornering ability of the wheels on the cornering inner side decreases due to a decrease in the wheel load. Further, since the lateral tire force of the wheel on the turning outer side changes nonlinearly, the cornering ability of the wheel on the turning outer side increases nonlinearly with an increase in the wheel load. Also, there is a region where the increase in wheel load does not necessarily coincide with an increase in cornering power.

Therefore, when a vehicle employing a tire having a ratio of tire section height to width of 70 is subjected to a turning acceleration of 0.3G, the reduction in the cornering ability of the wheel on the turning inner side is greater than the increase in the cornering ability of the wheel on the turning outer side, and therefore, the total cornering ability is reduced. This phenomenon is shown in fig. 5, using a straight line (as indicated by the single-dot chain line) connecting the cornering ability of the inner wheel and the cornering ability of the outer wheel in the case of a 0.3G turn and compared with the cornering ability before the start of turning (i.e. when the wheel load has not moved yet and all is 3.9 kN). In this way, it can be confirmed that the total turning ability is reduced on average, as indicated by the arrow. Similarly, the average cornering ability of a tire having a tire section height to width ratio of 70, which was subjected to a 0.5G cornering, is shown as a thin line in fig. 5. In this case, the reduction in the total cornering ability is even more pronounced (greater). The reason for the greater reduction is that the outboard wheels have reached the limit of cornering ability and enter a region where cornering ability does not increase with increasing wheel load. Similar graphs show the cases with tire section height to width ratios of 82 and 60, respectively, in both cases a similar reduction in cornering ability occurs due to shifting of wheel loads. The degree of this reduction is particularly significant in the case where the ratio of the section height to the width of the tire is 82, but even a tire having a ratio of the section height to the width of the tire of 60 shows a significant reduction in cornering ability.

If the wheel load is not moved during turning, the turning ability is not reduced and the vehicle behavior is stabilized without the turning performance being reduced. Even when it is not necessary to increase the maximum value of cornering ability, balanced wheel load distribution may be advantageous because it may enable selection of tires having a greater ratio of section height to width and thus achieve improved fuel efficiency. In other words, if the wheel load can be uniformly distributed during cornering so that the wheel load does not move and all the tires are uniformly used, a reduction in cornering ability can be avoided and vehicle behavior can be stabilized.

Although fig. 5 illustrates the effect of wheel load shifting on cornering ability, a similar trend occurs when cornering ability is replaced by a degree of deceleration G or acceleration G. In other words, when the wheel load has moved due to acceleration or deceleration, the tire friction force on the side where the wheel load has increased reaches a limit and the braking force or the acceleration force is limited. Meanwhile, on the side on which the wheel load has decreased, the tire has sufficient ability to increase the tire friction force, but a large tire friction force is not applied to the road because the wheel load is small. Therefore, the behavior of the vehicle during deceleration and acceleration can be stabilized by evenly distributing the wheel loads.

Fig. 6 shows the situation when the wheel positions, i.e. the track width and the wheel base, are controlled such that the wheel loads of the four wheels are distributed evenly. In the first embodiment, the positions of the wheels are changed so that the wheel loads of the four wheels are equal. Fig. 6 is a schematic view (a) showing the positions of the wheels and the center of gravity of the vehicle when the vehicle is viewed from above, and fig. 6 is a schematic view (b) showing the position of the wheels and the center of gravity of the vehicle from one side in a direction perpendicular to the direction of accelerationThe wheel position and center of gravity when viewing the vehicle. In the schematic diagram (a) of fig. 6, the angle is changed by turning, accelerating, decelerating or a combination thereof (i.e. yaw rate and centrifugal force in case of turning, accelerating or deceleratingLongitudinal acceleration in case of deceleration and both in case of acceleration or deceleration in case of turning) of the vehicle center of gravity is shown as total acceleration G _(x，y) . Total acceleration G _(x，y) Is set as a total acceleration direction axis CA _(h) . An axis perpendicular to the plane of view shown in the schematic view (a) of fig. 6 and an axis passing through the center of gravity G of the vehicle are set as a total acceleration direction vertical axis CA _(p) 。

Total acceleration vector G _(x，y) Determined from acceleration and yaw rate sensors 120 mounted to the vehicle body. The X direction and the Y direction are determined according to the position and the direction in which the sensor is mounted to the vehicle body. Generally, the X direction corresponds to the longitudinal direction of the vehicle body, and the Y direction corresponds to the lateral (transverse) direction of the vehicle body.

Axis CA perpendicular to the direction of total acceleration _(p) Along the total acceleration vector G _(x，y) Is translated by a distance l ₂ The corresponding axis is set as the acceleration backward axis. Similarly, the axis CA is perpendicular to the direction of the total acceleration _(p) Along the total acceleration vector G _(x，y) Is translated by a distance l in the opposite direction ₁ The corresponding axis is set as the acceleration forward axis. The acceleration backward axis and the acceleration forward axis serve as virtual axles.

If the acceleration of the vehicle's center of gravity G in the vertical direction (acceleration due primarily to gravity) is represented as a vector G _(z) And the height of the center of gravity from the road surface is represented as h, the wheel load W acting on the acceleration backward axis ₂ And wheel load W acting on the acceleration forward axis ₁ Can be expressed as the following equation set (1)

Equation set (1)

G _(x，y) ＝{(G _(x) +ΔG _(x) 2)+(G _(y) +ΔG _(y) 2) }1/2: total acceleration

Wherein

G _(i) : detected by acceleration and yaw rate sensors

ΔG _(i) : attitude correction acceleration calculated from target vehicle attitude

m: vehicle mass

h: height of center of gravity

G _(z) : acceleration due to gravity

In order to suppress the movement of the wheel load and stabilize the behavior of the vehicle, the wheel load W acting on the acceleration rearward axis ₂ Should be equal to the wheel load W acting on the forward axis of acceleration ₁ I.e. the value W determined by equation set (1) ₁ And W ₂ Should become approximately equal. Since it is clear from the equation set (1), the equivalent valuel ₁ And l ₂ Near infinite, value W ₁ And W ₂ Become approximately equal regardless of G _(x，y) The size of (2). The reason is that the wider the interval between the wheels, the smaller the amount of movement of the wheel load due to the total acceleration, and the more stable the vehicle behavior becomes. This phenomenon corresponds to the well-known concept of wide track and long wheelbase.

In the aforementioned vehicle employing the variable wheel geometry, in order to achieve a compact vehicle size and stable vehicle performance, the track width is widened and the wheel base is lengthened to stabilize the vehicle when the vehicle travels at a high speed (high-speed travel and/or meandering travel) under a condition where a large acceleration can occur. Meanwhile, when the vehicle is running at a low speed without occurrence of a large acceleration (e.g., city streets), the wheel positions are changed to obtain a narrow wheel base and a short wheel base to make the vehicle more compact and improve the turning performance. However, the movement of the wheel load can be suppressed without using a wide track width and a long wheel base, in view of the direction of the total acceleration.

In other words, the wheel load of four wheelsThe load can satisfy the relation W ₁ ＝W ₂ I.e. by adjusting l ₁ And l ₂ So as to implement the following equations to become equal

Equation set 2

l ₂ G _(z) -hG _(x，y) ＝l ₁ G _(z) +hG _(x，y)

(l ₂ -l ₁ )G _(z) ＝2hG _(x，y)

1-l _rate ＝2h _rate G _rate

l _rate ＝1-2 _hrate G _rate

Wherein

G _rate ＝G _(x，y) /G _(z) : acceleration ratio

l _rate ＝l ₁ /l ₂ : geometric size ratio

h _rate ＝h/l ₂ : height ratio

Using the above equation, the position of the two virtual axles corresponding to the even distribution of wheel loads for the four wheels produces a total acceleration G in a particular direction _(x，y) Is determined. The wheel load of the four wheels is then evenly distributed by arranging the four wheels such that the wheels rotate about an axis coinciding with the virtual wheel axis.

The wheel loads of the left and right wheels of each virtual wheel axle depend on W as shown in the diagrams (d) and (c) of FIG. 6 ₁ And W ₂ . When the wheel movement path is perfectly circular as in this embodiment, merely arranging the wheels on the axis corresponding to the virtual wheel axis may make the two wheels equidistant from the center of gravity of the vehicle. Thus, calculating the wheel load distribution of the left and right wheels with respect to the virtual wheel axis may be omitted.

FIG. 7 shows the movement l ₁ And l ₂ In the range ofWithin this range, the axle load W can be distributed uniformly ₁And W ₂ . FIG. 7 is a graph obtained by calculating l on the assumption that the height h of the center of gravity is 0.5 m ₁ And l ₂ Is obtained from the movable range of (a). FIG. 7 shows that uniform axle loads are obtained ₁ And l ₂ Is plotted against the plane acceleration (G) and takes the form of a uniform wheel load plane alpha.

Using FIG. 7, the vehicle acceleration G can be obtained _rate L at 1.1G ₁ And l ₂ In which the wheel loads of the four wheels can be equally distributed while minimizing the distance between the axles (assuming a coefficient of friction of approximately 1.0 and the absence of a dedicated downward force), which is the maximum value that is generally achievable for a vehicle.

The wheel load can be determined by setting l, as shown by line min in FIG. 7 ₁ =0 and l ₂ 1.1 meters (corresponding to point E) and is distributed uniformly under maximum acceleration conditions. Thus, line min represents the minimum range of movement over which uniform wheel load distribution can be achieved. In other words, as long as the vehicle is set such that ₁ And l ₂ Can vary from 0 to 1.1 m, the wheel load can correspond to an acceleration G of up to 1.1G in either direction _rate Are evenly distributed.

Now further referring to fig. 7, it will be explained that l can be varied from 0 to 1.1 meters ₁ And varying l from 0 to 1.1 meters ₂ Of the vehicle. For example, assume that the initial position of the wheel is l ₁ Is 0.8 m and l ₂ Is 0.8 m. This corresponds to point a in fig. 7. If the vehicle is traveling without accelerating, decelerating or turning, the acceleration is 0G, and therefore the point corresponding to the wheel geometry is the uniform wheel load plane α.

Now, consider a case where 0.2G turning acceleration has been generated and the wheel position has moved to point B. Since uniform wheel load distribution cannot be achieved unless a point on the uniform wheel load plane α is achieved, the control search performed can accelerate at 0.2GValue of i for achieving uniform wheel load distribution in degree ₁ And l ₂ 。

In the first embodiment of the present invention, the control performed finds the wheel position, i.e., l ₁ And l ₂ Such that all wheels are movable an equal amount. More specifically, the wheel position changes by Δ l as the wheel geometry moves from point A to point B ₁ = 0.1 and Δ l ₂ = 0.1, given by Δ l when the wheel geometry is moved from point a to point B ₁ = 0.2 and Δ l ₂ And = 0. In the case of point B', the total movement amount is realized with two actuators, and in the case of point B, the total movement amount is realized with four actuators. Assuming that the speeds of the actuators used are all the same, the wheel geometry can move more quickly to point B because the amount of movement is divided among the four actuators. Similarly, the wheel geometry moves to point D as the acceleration increases. If the acceleration increases beyond point D, the wheel geometry moves toward point E. When the wheel geometry moves from point D towards point E, only l ₁ The value of (d) is changed and an even distribution of actuator movements cannot be maintained. However, this shift is dependent on producing more than 0.6G plusThe frequency at which the speed is set.

The effects of the first embodiment will now be explained, and the vehicle employing the variable wheel geometry structure according to the first embodiment achieves the following effects.

(1) In the first embodiment, the vehicle is equipped with a steering actuator 340, and the actuator 340 is mounted on each wheel 390 and is used to change the direction of the wheel 390 with respect to the vehicle body 100. Also, a track and wheel base changing actuator 350 is disposed between each wheel 390 and the vehicle body 100 and serves to move the wheel to any desired position along a predetermined path (wheel unit moving path 200). The controller 500 is configured to determine a target wheel geometry according to a driving state of the vehicle and to transmit a wheel position change command to the track and wheel base actuator 350 according to the target wheel geometry. As a result, a vehicle having a compact structure, a high traveling ability, and a simple structure can be realized while energy consumption can be controlled.

(2) The controller 500 changes the wheel positions so that the wheel loads of all wheels are equal. As a result, the vehicle behavior can be improved during cornering.

(3) The vehicle is provided with an acceleration and yaw rate sensor 120 to detect an acceleration vector of the vehicle in a horizontal plane, and the controller 500 changes the wheel position using the direction of the detected acceleration vector as a reference. As a result, the control is performed according to a single direction, so that the control can be simplified.

(4) The controller 500 is configured to divide the wheels 390 into two pairs, each pair being located on opposite sides of an axis perpendicular to the acceleration vector, and to vary the position of the wheels 390 depending on the distance between each pair of wheels 390 and the vertical axis. As a result, since the wheel loads of the left and right wheels of each pair are balanced (i.e., equal to each other), the control can be simplified because only the wheelbase that achieves an equal wheel load (i.e., the distance l from the center of gravity to the acceleration front axis) needs to be set ₂ And the distance l from the center of gravity in the opposite direction to the acceleration rearward axis ₁ )。

(5) Since each wheel 390 moves along the wheel unit moving path 200 that takes a single circular path, the track and wheel base can be changed while maintaining a predetermined relationship therebetween.

(6) Since the circular movement path is close to a perfect circle, the two wheels arranged on each virtual wheel axle may be arranged at a distance from the total acceleration G _(X，Y) With equal distance and equal distribution of the wheel load of the two wheels arranged on each axle. As a result, the control can be simplified.

Second embodiment

A second embodiment will now be described in which the wheel positions are changed in accordance with the target wheel load distribution corresponding to the running state of the vehicle. Although the wheel load is equally distributed in the first embodiment, in this embodiment, the wheel load is not equally distributed according to the situation.

The constituent features of the second embodiment are the same as those of the first embodiment except for the wheel load distribution control (as described above), and the description and drawings thereof are omitted for the sake of brevity.

Fig. 8 shows a case where the track width and the wheel base are controlled so that the wheel load of four wheels is freely distributed. More specifically, the wheel load distribution, i.e. the wheel geometry, is controlled such that the wheel load of the driving wheels increases.

In the first embodiment, the wheel load is equally distributed so that the tires of all four wheels are equally used. When all wheels are functionally identical, the behavior of the vehicle can be stabilized by equally distributing the wheel loads, such as during braking and cornering. When the function of the wheels is different, such as the drive wheels versus the non-drive wheels, the vehicle behavior does not have to be stabilized by equally distributing the wheel loads. For example, during acceleration, a larger driving force can be transmitted to the road surface by increasing the wheel load of the driving wheels. At the same time, increasing the wheel load of the non-driving wheels does not contribute to the transmission of the driving force. During acceleration, therefore, the wheel load of the drive wheels is preferably increased to such an extent that the friction limit of the tires or the straightness of the vehicle is not reduced. Particularly in rear wheel drive vehicles, the wheel load of the drive wheels (rear wheels) tends to increase during acceleration due to rearward displacement of the vehicle body relative to the wheels. Therefore, if the wheel load distribution control is performed during acceleration to equally distribute the wheel load, the control performed will act to return the wheel load, which naturally moves backward to the rear wheels, to the front wheels. Therefore, there is a possibility that the wheel load of the rear wheels does not increase and the acceleration performance is degraded due to the influence of the wheel load distribution control.

In the second embodiment, similarly to the first embodiment, the acceleration of the center of gravity is expressed as a total acceleration vector G of accelerations in two arbitrary directions in the motion plane _(X，Y) . Root of herbaceous plantAccording to the total acceleration vector G _(X，Y) The control setting being made is from the center of gravity (i.e. from and G) _(X，Y) Perpendicular vector G _(z) Vector axis) along the total acceleration vector G _(X，Y) To the acceleration forward axis ₂ And from the center of gravity along the total acceleration vector G _(X，Y) To the rearward axis of acceleration ₁ . The equation set (2) used in the first embodiment is modified to equation set (3) as shown below for the second embodiment.

Equation set (3)

l ₂ G _(z) -hG _(x，y) ＝l ₁ G _(z) +hG _(x，y)

(l ₂ -l ₁ W _rate )G _(z) ＝h(l ₁ +W _rate )G _(x，y)

W _rate ＝W ₁ /W ₂ : wheel load ratio

Using the above equation, it is determined that the total acceleration G is generated in a specific direction _(x，Y) The position of the two virtual wheel axles corresponding to an even distribution of the wheel load of the four wheels. Then by arranging fourThe wheels are rotated about an axis coincident with the virtual wheel axis to set a wheel load ratio of the virtual wheel axis to W _rate . In other words, when the driving wheel 300 is accelerating and the acceleration direction is along the longitudinal direction of the vehicle body, the controller 500 sets the ratio W _rate Set to any value from 0 to 1.

If the vehicle is turning or braking, then the ratio W _rate Is set to 1 (W) _rate = 1) and the wheel geometry is controlled to obtain equal wheel load distribution in the same way as in the first embodiment. The wheel movement control is the same as that of the first embodiment (described above), and for the sake of brevity, it is doneThe description of (a) is omitted here.

The effects of the present embodiment will be explained below. The vehicle having the variable wheel geometry according to the second embodiment achieves the following effects.

(7) The controller 500 may change the wheel position according to the running state of the vehicle so as to obtain any desired wheel load ratio. As a result, in addition to controlling the wheel positions so as to obtain a uniform wheel load distribution, the controller 500 can suppress the slip of the drive wheels, for example, by setting the wheel load distribution such that the wheel load of the drive wheels is increased.

Third embodiment

The third embodiment shows a case where the wheel position is changed in accordance with the target vehicle posture. The constituent features of the third embodiment other than the wheel load distribution control (as described in the above-described first and second embodiments) are the same as those of the first and second embodiments, and the description and drawings thereof are omitted for the sake of brevity.

Fig. 9 shows a case where the track width and the wheel base are controlled so that the wheel loads of the four wheels are freely distributed. In the third embodiment, the wheel load is changed in accordance with the target vehicle posture. In the third embodiment, similarly to the first embodiment, the acceleration of the center of gravity is expressed as a total acceleration vector G of accelerations in any two directions in the motion plane _(x，y) . According to the total acceleration vector G _(x，y) The control setting made is from the center of gravity (i.e., from and G) _(x，y) Perpendicular vector G _(z) Vector axis) along the total acceleration vector G _(x，y) To the acceleration forward axis ₂ And along the total acceleration vector G from the center of gravity _(x，y) To the acceleration backward axis ₁ 。

Equation set (4)

In the equation, tan θ is an attitude angle in the acceleration direction, and the value k is an elastic coefficient for a portion between the wheel and the vehicle body (mainly suspension) of the vehicle.

From the above equation it is clear that if there is a total acceleration G when in a particular direction _(x，y) Hour wheel load W ₁ And W ₂ Is freely adjusted to any desired value, the attitude angle of the vehicle can be controlled. Such asIf the wheel position is controlled in the manner of the first embodiment, the wheel load will be equally distributed and W ₁ Will be equal to W ₂ . Therefore, the attitude angle will be 0 ° and the vehicle will always have a flat attitude. Conversely, if the wheel position is controlled in the manner of the second embodiment, the wheel load will be self-distributed and the desired attitude angle can be obtained.

In the third embodiment, the posture-correcting acceleration Δ G _(i) The calculation is performed based on the target vehicle attitude based on the roll angle and the pitch angle. Distance l ₁ And l ₂ Is set to satisfy the posture correction acceleration Delta G _(i) . In this way, a desired vehicle attitude can be obtained, and the vehicle behavior can be stabilized by suppressing roll generated when the vehicle turns or is blown by a side wind and pitch generated when the vehicle runs on a bumpy road or is rapidly accelerated or decelerated (braked).

The effects of the present embodiment will be explained below. The vehicle employing the variable wheel geometry according to the third embodiment achieves the following effects.

(8) Since the controller 500 changes the wheel positions based on the target vehicle posture set according to the vehicle running state, the target vehicle posture suitable for the running state can be achieved.

(9) Since the controller 500 sets the target vehicle attitude according to the vehicle roll angle, the roll angle can be freely set. As a result, for example, the roll angle can be prevented from increasing during cornering or a side wind, and the vehicle behavior can be stabilized.

(10) Since the controller 500 sets the target vehicle attitude according to the vehicle pitch angle, the pitch angle can be freely set. As a result, for example, the vehicle can be prevented from sinking during rapid acceleration and falling over during rapid braking.

Fourth embodiment

A fourth embodiment will now be explained. The fourth embodiment shows a case where the reference wheel is set in accordance with the acceleration direction and the wheel position in addition to the movement of the reference wheel. The constituent features of the fourth embodiment are the same as those of the first embodiment except for the wheel movement control (as described above), and the description and drawings thereof are omitted for the sake of brevity.

Although the movement of the wheel positions is calculated in the first embodiment such that all the wheels move by the same amount (distance), in the fourth embodiment one of the virtual wheel axes remains fixed with respect to the center of gravity of the vehicle and the other virtual wheel axis is moved. More specifically, if the distance from the center of gravity to a virtual wheel axle positioned in the direction of acceleration relative to the center of gravity is l ₂ And the distance from the center of gravity to a virtual wheel axle positioned in the direction opposite to the direction of acceleration is l ₁ Then only the wheel axle distance l ₁ Is changed.

Similar to the first embodiment, fig. 10 shows uniform wheel load planes α and l ₁ And l ₂ Movable to equally distribute axle load W ₁ And W ₂ The range of (1).

Similarly to the first embodiment, assume, for example, that the initial positions of the wheels are such that ₁ Is 0.8 m and l ₂ 0.8 meters, as shown in fig. 10 as initial position point a. When l is ₂ When the value of (c) is fixed, the wheel load can be varied by varying l alone for acceleration to approximately 0.8G ₁ Is equally assigned (moving from point a to point B). The specific driving conditions under which this type of wheel geometry change can be speculatively used will now be explained.

Fig. 11 shows a wheel arrangement employed during acceleration. In the fourth embodiment, the wheel positions are set such that the wheel base is longer than the wheel base when the vehicle is traveling at a constant speed and is not accelerating. However, when the vehicle accelerates, the rear wheels are set as reference wheels (kept fixed), and the front wheels move backward so as to obtain a predetermined wheel posture. In other words, when the vehicle accelerates, the wheel load of the front wheels decreases and the wheel load of the rear wheels increases. Therefore, by moving only the front wheels, the load applied to the track and wheel base changing actuators 350 can be reduced (because the wheel load of the front wheels is smaller) and the control response can be increased. Also, by moving the front wheels toward the rear of the vehicle, the change in wheel load of all the wheels can be controlled with respect to the rearward movement of the center of gravity that occurs during acceleration. As a result, the vehicle behavior can be stabilized during acceleration.

Fig. 12 shows a wheel arrangement employed during deceleration. When the vehicle decelerates, the front wheels are set as reference wheels (kept fixed), and the rear wheels move forward so as to obtain a predetermined vehicle attitude. In other words, when the vehicle decelerates, the wheel load of the front wheels increases and the wheel load of the rear wheels decreases. Therefore, by moving only the rear wheels, the load applied to the track and wheel base changing actuators 350 can be reduced (because the wheel load of the rear wheels is smaller) and the control response can be increased. Also, by moving the rear wheels toward the front of the vehicle, the change in wheel load of all the wheels can be controlled with respect to the forward movement of the center of gravity that occurs during deceleration. As a result, the vehicle behavior can be stabilized during deceleration.

Fig. 13 shows the wheel arrangement employed during cornering. When the vehicle turns, the wheel on the turning outer side is set as a reference wheel (kept fixed), and the wheel on the turning inner side is moved inward toward the longitudinal center of gravity axis (center) of the vehicle so as to obtain a predetermined vehicle attitude. In other words, when the vehicle turns, the wheel load of the inner wheel decreases, and the wheel load of the outer wheel increases. Thus, by moving only the inner wheel, the load applied to the track and wheelbase changing actuator 350 may be reduced (because the wheel load of the inner wheel is smaller) and the control response may be increased. Also, by moving the inner wheels towards the vehicle longitudinal centre axis, the change of wheel load of all wheels can be controlled in relation to the movement of the centre of gravity towards the outer side of the curve that occurs during cornering. As a result, the vehicle behavior can be stabilized during cornering.

Fig. 14 shows a vehicle arrangement adopted when the vehicle decelerates and turns a curve at the same time. When the vehicle decelerates and turns, the wheel on the turning outer side closer to the shifted center of gravity is set as the reference wheel (kept fixed) and the other three wheels move inward in an appropriate direction so as to suppress the change in the wheel load and obtain a predetermined wheel posture. In other words, when the vehicle decelerates and turns while turning, the wheel load of the front wheels on the turning outer side becomes maximum. Therefore, by setting the front wheel on the turning outer side as the reference wheel and moving the other three wheels, the load applied to the track and wheel-base changing actuator 350 can be reduced (since the wheel load for the other three wheels is smaller) and the control response can be increased.

Fig. 15 illustrates the manner in which the actuator load is reduced. The figure shows a case where turning is started and the turning inertia force gradually increases. The solid line curve shows the load pattern of this embodiment, and the broken line shows the load pattern of the first embodiment. The thin lines show the load patterns obtained when the load control is not performed.

At time t0, the turning acceleration is not yet generated, and the load (load-m) acting on the actuator corresponds to the vehicle weight. After the start of turning, if the vehicle position is controlled in the manner of the first embodiment so that the wheel loads are always equal, the actuator will always require the actuator driving force Load-a corresponding to the Load-m. However, if the actuator is driven after the turning inertia force has occurred and the wheel Load has moved, the wheel position can be moved by the smaller actuator driving force Load-B.

Finally, this embodiment requires the actuator driving force Load-a to achieve uniform Load distribution, similarly to the first embodiment. However, there are few cases where very uniform wheel loads are required, and some unevenness is acceptable as long as the friction limit of the outer wheels is not exceeded. Briefly, with this embodiment, the required actuator driving force can be reduced under most vehicle driving conditions.

As shown in fig. 15, a larger actuator driving force Load-C is required to move the outer wheels whose wheel loads have increased. When the turning inertia force can be predicted using a navigation system or the like or an increase in the turning inertia force can be predicted according to the driving conditions, the control according to the present invention should stop and the inner wheels should be quickly moved to a position where an equivalent wheel Load is obtained using the actuator driving force Load-a before the inner wheels have moved to their moving range limits, after which both the inner and outer wheels can be moved using the actuator driving force Load-a even if the rotational inertia force increases. In this way, the maximum driving force required by the actuator may be limited to Load-A.

The effects of the present embodiment will be explained below. The vehicle employing the variable wheel geometry according to the fourth embodiment achieves the following effects.

(11) Since the controller 500 changes the wheel position such that the wheel load of the wheel is changed to a smaller extent, the vehicle behavior is stabilized.

(12) When the controller 500 changes the wheel position, the controller 500 sets one wheel as the reference wheel and changes the positions of the wheels other than the reference wheel. As a result, vehicle stability can be increased and control can be simplified compared to the case where all wheels are moved.

(13) Since the controller 500 sets the wheel or wheels having a larger wheel load as the reference wheel or wheels and changes the position of the wheel having a smaller load, the control response may increase and the energy required to move the wheel may decrease.

(14) Since the controller 500 sets the wheel or wheels closer to the center of gravity shift as the reference wheel or wheels and changes the positions of the other wheels, the control response may increase and the energy required to move the wheels may decrease.

Fifth embodiment

A fifth embodiment will now be explained. In the fifth embodiment, the wheel moving path is provided such that the wheels can move in the vertical direction of the vehicle in addition to the horizontal direction.

Fig. 16 shows a vehicle employing a variable wheel geometry according to a fifth embodiment. In the fifth embodiment, the wheel unit moving path 200 is curved in the vertical direction of the vehicle. Thus, as the wheel position changes horizontally (as viewed from the top plan view), the height of the wheel also changes. The guide rail provided on the vehicle body described later with respect to the sixth embodiment may be used as a practical structure to realize the wheel unit movement path 200 along which the wheel unit moves. In the present embodiment, only the shape of the guide rail is explained.

As shown in the schematic view (a) of fig. 16, when the vehicle is viewed from above (top plan view), the wheel moving path is the same as that of the first to fourth embodiments, i.e., a single circular path centered on the center of gravity. Meanwhile, as shown in the schematic view (b) of fig. 16, when the vehicle is viewed from the side, both ends of the moving path are inclined upward, not in the horizontal direction. Further, as shown in the schematic view (c) of fig. 16, when the vehicle is viewed from the rear (or front), both ends of the moving path are inclined downward, not in the horizontal direction.

The diagrams (a) to (c) of fig. 18 and the diagrams (a) to (c) of fig. 19 show the manner in which the movement of the wheel unit 400 (or 300) along the wheel moving path 200 shown in fig. 16 is associated with the change in the center of gravity.

As shown in the schematic diagrams (a) to (c) of fig. 17, the wheel movement theory is set such that the position of the center of gravity of the vehicle lowers when the wheel position moves from the reference position in the direction of arrow B such that the track width decreases and the wheel base increases. As shown in fig. 18, when the wheel unit on one side is moved in the direction of arrow B (i.e., in the direction of decreasing the track width and increasing the wheel base) and the wheel unit on the other side is moved in the direction of arrow a (i.e., in the direction of increasing the track width and decreasing the wheel base), the wheel is assumed to be in a state of being laterally inclined with no change in the center of gravity.

Fig. 19 and 20 show two other preferred embodiments of the wheel movement path, which is arranged such that the wheels move in the vertical direction in addition to the horizontal direction.

The wheel moving path shown in fig. 19 is set such that the position of the center of gravity is lowered when the wheel moves in the direction of arrow a, which is a direction to increase the wheel base and decrease the wheel base. Similarly, the wheel movement path is set such that the position of the center of gravity is lowered when the wheel is moved in the direction of arrow B, which is a direction to decrease the wheel base and increase the wheel base.

As shown in the schematic view (a) of fig. 19, when the left and right wheel units are moved in opposite directions, i.e., the a and B directions, respectively, the center of gravity of the vehicle is lowered. Similarly, when both the left and right wheel units move in the B direction as shown in the schematic diagram (B) of fig. 19 or in the a direction as shown in the schematic diagram (c) of fig. 19, the center of gravity of the vehicle lowers.

With this structure, the center of gravity always becomes low when the wheel position is shifted. Therefore, the value h of the equation set (1) of the first embodiment becomes small and the effect of moving the wheel position becomes more remarkable. Therefore, even if the amount of wheel movement is small, the wheel positions can be controlled in the manner of the first embodiment so as to obtain equivalent wheel load distribution.

The shape of the wheel travel path shown in fig. 19 achieves advantageous results when all the wheels are moved the same amount in the manner of the first embodiment, since all the wheels have the same height position relative to the center of gravity. In contrast, when the wheel bearing a large wheel load is set as the reference wheel (kept fixed) and the other wheels are moved in the manner of the fourth embodiment, the heights of the wheel bases are different, and therefore, there is a case where the center of gravity of the vehicle is not moved to a favorable position. Therefore, the wheel movement path shown in fig. 20 (the same as fig. 17) is provided so that the height position of the wheel with respect to the center of gravity of the vehicle does not change when the wheel moves in the direction of arrow a, i.e., in the direction of increasing the wheel base and decreasing the wheel base. Conversely, when the wheel moves in the direction of arrow B, that is, in the direction of decreasing the wheel base and increasing the wheel base, the height position of the wheel relative to the center of gravity of the vehicle changes so that the center of gravity lowers.

As shown in the schematic view (a) of fig. 20, when the left and right wheel units are moved in opposite directions, for example, the a direction and the B direction, respectively, the wheel unit in the B direction is moved so that the center of gravity of the vehicle is lowered and the movement of the wheel unit in the a direction does not change the position of the center of gravity. Thus, the vehicle body becomes inclined. Similarly, when both the left and right wheel units are moved in the B direction as shown in the schematic view (B) of fig. 19, the center of gravity of the vehicle is lowered, and when both the left and right wheel units are moved in the a direction as shown in the schematic view (c) of fig. 19, the position of the center of gravity of the vehicle is not changed.

With the wheel moving path shown in fig. 20, the center of gravity of the vehicle does not change when the wheel moves as shown in fig. 11, which is the wheel movement used in the fourth embodiment when the vehicle accelerates. Similarly, the center of gravity does not change when the wheels are moving as shown in fig. 12 and the vehicle is decelerating.

Meanwhile, when the vehicle turns and the wheels on the turning inner side move as shown in fig. 13, the vehicle height decreases on the inner side of the vehicle (the side portion of the vehicle on the turning inner side) and the vehicle behavior is more stable than the fourth embodiment due to the adoption of the roll canceling action that lowers the vehicle inner side. Thus, the amount of wheel movement may be reduced. When the wheel movement path is set such that the vehicle tilts and the center of gravity of the vehicle changes when the wheel moves in the a direction shown in fig. 11 or 12, the movement of the center of gravity serves to degrade the wheel load distribution, and therefore, such a wheel movement path is not ideal. In short, when the wheel (or wheels) carrying more wheel load is set as the reference wheel and the other wheels move, the wheel moving path as shown in fig. 20 is preferable.

The choice of whether to use the wheel movement path shown in fig. 19 or the wheel movement path shown in fig. 20 depends on factors such as the wheel movement actuator capabilities and the desired vehicle performance. For example, if the wheel movement actuator is powerful and requires a high level of vehicle performance, a vehicle with a high level of performance can be realized by selecting the wheel movement path shown in fig. 19 and performing wheel movement control according to the first embodiment.

Conversely, if the required level of vehicle performance is not so high, a lower-cost vehicle can be realized by selecting the wheel movement path shown in fig. 20 and performing the wheel movement control according to the fourth embodiment.

The wheel moving path may be obtained in other ways than the rail provided as described above such that the wheel unit moves in the vertical and horizontal directions. For example, the wheel unit may be moved up and down as it is horizontally moved along the wheel moving path using a rotary screw or a ball screw provided at a position where the wheel unit is mounted to the vehicle body, which is designed to raise and lower the suspension arm, the cam mechanism, or a device in which a mounting shaft of the suspension arm is arranged in an oblique direction.

With these methods, the amount of vertical movement of the movement path can be freely set, rather than being set in advance according to the position of the wheel unit along the guide rail.

The effects of the fifth embodiment will now be explained. The vehicle employing the variable wheel geometry structure according to the fifth embodiment achieves the following effects.

(15) The wheel moving path 200 is provided such that the wheel unit moves in the vertical direction as well as the horizontal direction of the vehicle, generating movement in a three-dimensional space. Thus, when changing the position of the wheels, the height of the vehicle can be adjusted in addition to changing the track and wheelbase. As a result, the posture of the vehicle can be controlled with a higher degree of freedom, and the vehicle behavior can be improved to a higher degree.

Sixth embodiment

Fig. 21 (a) and 21 (b) show a mounting structure for a wheel having a variable wheel geometry according to a sixth embodiment. In the sixth embodiment, the suspension frame 600 is supported on the vehicle body 100 so that it can rotate relative to the vehicle body 100 using a slider or rail 670 that is annular (circular ring shape) and is disposed near the lower side portion of the vehicle body 100 and a linear motor slider or rail 615 that is annular and is disposed near the middle side portion of the vehicle body 100. Otherwise, the constituent features are the same as those of the first embodiment shown in fig. 3, and the description thereof is omitted for the sake of brevity. Since the suspension frame 600 is supported on the side portion of the vehicle body, the center of gravity can be lower than that of the first embodiment and the running ability can be increased more than that of the first embodiment.

Seventh embodiment

Fig. 22 (a) and 22 (b) show a wheel mounting structure for a vehicle having a variable wheel geometry structure according to a seventh embodiment. In the seventh embodiment, an articulated suspension frame 680 is mounted to the bottom surface of the vehicle body 100 (or the bottom surface of another suspension frame) using a bearing 610 and a linear motor slider or guide 615 that is annular (circular ring shape) and is disposed at the middle portion of the vehicle body 100. Thus, the suspension frame 680 is supported so that it can rotate relative to the vehicle body 100.

A damper 690 is disposed between the linear motor block 615 and the suspension frame 680 to absorb vibration applied to the wheel 390 from the road surface. Otherwise, the constituent features are the same as those of the first embodiment shown in fig. 3, and the description thereof is omitted for the sake of brevity. With the seventh embodiment, since the shock absorbers 690 are provided between the suspension frame 680 and the vehicle body 100, a comfortable ride feeling and a good running environment can be obtained.

Eighth embodiment

Fig. 23 (a) and 23 (b) show a mounting structure for a wheel having a variable wheel geometry according to an eighth embodiment. The eighth embodiment employs a double wishbone suspension frame 700 configured to suspend a wheel 390 using an upper arm 710 and a lower arm 720. The upper arm 710 is supported on a linear motor slide or rail 615 that is annular in shape and disposed in a mid-portion of the vehicle body 100, and the lower arm 720 is supported on a slide or rail 670 that is annular in shape and disposed near a lower portion of the vehicle body 100. Shock absorbers 730 are disposed between upper arm 710 and lower arm 720.

By using the double-wishbone-type suspension frame 700, the eighth embodiment is able to control alignment changes and vehicle attitude with greater freedom during acceleration/deceleration by adjusting the shape and arrangement of the arms. In addition, the rigidity of the double wishbone suspension is higher, and thus steering performance and stability are improved.

Ninth embodiment

Fig. 24 (a) and 24 (b) show a wheel mounting structure for a vehicle having a variable wheel geometry structure according to a ninth embodiment. The ninth embodiment employs a floating deck-type suspension frame 740 disposed between the vehicle body 100 and the vibration damping member 750. The suspension frame 740 is supported on the vehicle body 100 such that it can rotate relative to the vehicle body 100 by using a slider or guide rail 670 disposed near a lower portion of the cushioning member 750 and a linear motor slider or guide rail 615 that is annular and disposed near an upper portion of the cushioning member 750. A lower end portion of the cushioning member 750 is fixed to the vehicle body 100 by a coil spring 760. Otherwise, the constituent features are the same as those of the first embodiment shown in fig. 2, and the description thereof is omitted for the sake of brevity. With the ninth embodiment, since the floating deck type suspension frame 740 is used, comfortable ride feeling and good running environment can be obtained.

Tenth embodiment

Fig. 25 (a) and 25 (b) show a wheel mounting structure for a vehicle having a variable wheel geometry structure according to a tenth embodiment. In the tenth embodiment, the suspension frame 740 is supported on the vehicle body 100 so that it can rotate relative to the vehicle body 100 by using the slider 670 disposed near the lower portion of the cushioning member 750 and the gear transmission 770 that is annular and disposed near the upper portion of the cushioning member 750. Otherwise, the constituent features are the same as those of the first embodiment, and the description and drawings thereof are omitted for the sake of brevity.

Eleventh embodiment

Fig. 26 (a) to 26 (c) show a wheel mounting structure for a vehicle having a variable wheel geometry according to an eleventh embodiment. In the eleventh embodiment, each suspension frame 600 is mounted to a different position of the vehicle body 100 via a bearing 610 provided on the bottom surface of the vehicle body 100 (or another suspension frame bottom surface). A linear actuator (cylinder) 680 provided on a lower side portion of the vehicle body 100 serves as the wheel base and wheel base changing actuator 350. Each suspension frame 600 is pivoted about the mounting member shown in fig. 26 (c) by extending and retracting the rod of each linear actuator 680. Otherwise, the constituent features are the same as those of the first embodiment, and the description thereof is omitted for the sake of brevity. With this embodiment, since the linear actuator is arranged on the vehicle body, a larger actuator can be used.

Twelfth embodiment

Fig. 27 (a) and 27 (b) show a wheel mounting structure for a vehicle having a variable wheel geometry according to a twelfth embodiment.

As shown in fig. 27 (b), the twelfth embodiment employs a double-wishbone-type suspension frame 700 configured to suspend a wheel 390 from an upper arm 710 and a lower arm 720. The upper arm 710 is supported on a linear motor slide or rail 615 that is annular in shape and disposed near a mid-side portion of the vehicle body 100, and the lower arm 720 is supported on a slide 670 that is annular in shape and disposed near a lower-side portion of the vehicle body 100. Shock absorbers 730 are disposed between upper arm 710 and lower arm 720.

With this embodiment, as shown in fig. 27 (a), the slider 670 and the linear slider 615 are different in shape. The different shapes and vertical spacing of the slide 670 and the linear slide 615 combine to allow the wheel unit to move vertically as the track and wheelbase are changed. Otherwise, the constituent features are the same as those of the first embodiment, and the description thereof is omitted for the sake of brevity.

With the twelfth embodiment, the vertical wheel movement of the fifth embodiment can be achieved by a simpler structure.

Other embodiments

Although the preferred embodiments of the present invention have been described above, the specific constituent features of the present invention are not limited to the above. Various design modifications may be made without departing from the scope of the invention.

Fig. 28 shows an example of a wheel arrangement used when one of the drive wheels fails and the vehicle accelerates with only one drive wheel. The other drive wheels (normal drive wheels) are arranged on the longitudinal center line of the wheel. If the position of the normal drive wheels is not changed, the driving force exerted by the other drive wheels will generate a lateral sway moment and will degrade the turning performance of the vehicle.

Conversely, by moving the remaining drive wheels to a position on the vehicle longitudinal center line as shown in fig. 28 when one of the drive wheels fails, an increase in torque due to the drive force exerted by the remaining drive wheels can be prevented. As a result, a transverse rolling moment can be avoided when the drive wheels fail and stable driving can be continued.

FIG. 29 is a top plan view of another example of a vehicle employing a variable wheel geometry. The vehicle is a front-wheel drive vehicle having one drive wheel unit 300 disposed at a forward intermediate position of the vehicle body 100 and three non-drive wheel units 400. One of the non-drive units 400 is disposed at a rearward middle position of the vehicle body 100, and the other two non-drive units 400 are disposed to the left and right of the center of gravity of the vehicle body 100.

FIG. 30 is a top plan view of another example of a vehicle employing a variable wheel geometry. The vehicle is a three-wheeled rear-wheel drive vehicle having one non-drive wheel unit 400 at the front and two drive wheel units 300 at the rear.

FIG. 31 is a top plan view of another example of a vehicle employing a variable wheel geometry. The vehicle is a three-wheeled front-wheel drive vehicle having one drive wheel unit 300 at the front and two non-drive wheel units 400 at the rear.

Fig. 32 is a schematic view (a) showing an example of a vehicle designed to change a wheel position so as to move an entering gate (e.g., a door) into a road surface to facilitate entering and exiting (getting on and off) conveniently.

When entering or exiting the vehicle, as shown in the schematic view (a) of fig. 32, first, the steering actuator 340 is driven to orient the wheels 390 in the same direction as the wheel unit moving path 200. Then, the track and wheel base changing actuator 350 is driven to move the wheel 390 to the opposite side of the vehicle path as the entry 101. As a result, as shown in the schematic view (b) of fig. 32, the entry gate 101 can be moved closer to the floor and a completely flat entering and alighting can be achieved.

In this example, all of the wheels 390 do not move simultaneously when the wheel positions change. Instead, one wheel is set as the reference wheel (remains fixed), and the positions of the other wheels are changed. When completed, the vehicle body 100 can be prevented from rotating by setting the direction of the reference wheel 390 to be different from the direction of the wheel unit moving path 200.

Although the wheel unit moving path 200 is circular in the top plan view in the previous embodiment, the shape of the moving path may be freely set as desired. Fig. 33 shows that the shape of the movement path 200 is an ellipse (oval) in the diagram (a) of fig. 33, a rectangle in the diagram (b) of fig. 33, a diamond shape in the diagram (c) of fig. 33, a triangle in the diagram (d) of fig. 33. Further, the shape of the wheel unit moving path 200 is not limited to the circular ring shape. As shown in the diagrams (e) and (f) of fig. 33, it is also acceptable to set the lengths of the plurality of discontinuous paths 200a, 200b, and 200c according to the desired movement range of the wheel 390. In addition, it is also acceptable to use a combination of two or more of the control programs described with reference to each embodiment.

General interpretation of terms

In understanding the scope of the present invention, the term "comprising" and its derivatives, as used herein, are intended to be open ended terms that specify the presence of the stated features, elements, components, groups, integers, and/or steps, but do not exclude the presence of other unstated features, elements, components, groups, integers and/or steps. The foregoing also applies to words having similar meanings such as the terms, "including", "having" and their derivatives. Also, the terms "part," "section," "portion," "section" or "element" when used in the singular can have the dual meaning of a single part or a plurality of parts. The term "detecting" as used herein to describe an operation or function performed by a component, part, device or the like includes a component, part, device or the like that does not require physical detection, but rather includes performing a determination, measurement, modeling, prediction, calculation or the like of the operation or function. As used herein, the term "configured to" or "configured to" describe a component, section or portion of a device includes hardware and/or software that is constructed and/or programmed to perform the desired function. Moreover, the terms "means-plus-function" in the specification should be interpreted to include any structure that can be used to carry out the function of the elements of the invention. Terms of degree such as "substantially", "about" and "approximately" as used herein mean a reasonable amount of deviation of the modified term such that the end result is not significantly changed.

While only selected embodiments have been chosen to illustrate the present invention, it will be apparent to those skilled in the art from this disclosure that various changes and modifications can be made herein without departing from the scope of the invention. For example, the size, shape, location or orientation of the various components can be changed as needed and/or desired. Components that are shown directly connected or contacting each other may have intermediate structures disposed between them. The functions of one element may be performed by two, and vice versa. The structure and function of one embodiment may be utilized in other embodiments. Not all advantages may be required to be present in a particular embodiment at the same time. Every feature which is different from the prior art, alone or in combination with other features, also should be considered a separate description of other inventions by the applicant, including the structural and/or functional concepts embodied by such feature(s). Accordingly, the foregoing descriptions of the embodiments according to the present invention are provided for illustration only, and not for the purpose of limiting the scope of the invention.

Claims (22)

1. A variable wheel alignment vehicle comprising:

a vehicle body having a center of gravity;

a plurality of wheels rotatably mounted with respect to the vehicle body;

a suspension device operatively disposed between the wheel and the vehicle body;

a steering mechanism operatively connected to the suspension device to change the orientation of at least one of the wheels relative to the vehicle body;

a drive device operatively connected to at least one of the wheels to drive the wheel;

a wheel position change mechanism operatively connected to the suspension device to move the suspension device relative to the vehicle body along a path of travel and to maintain the suspension device at any position along the path of travel; and

a wheel position control device operatively connected to the wheel position changing mechanism to issue a movement command to the wheel position changing mechanism, the movement command changing a wheel alignment distance between a center rotational axis of one of the wheels and the center of gravity of the vehicle body measured in a direction parallel to an acceleration direction of the center of gravity of the vehicle body, in accordance with a running condition of the vehicle.

2. The variable wheel alignment vehicle of claim 1, wherein

The wheel-position changing mechanism is operatively connected to the suspension device to move the suspension device horizontally relative to a center point located at a single location of the vehicle to change the wheel position such that the track and wheel base of the vehicle are changed.

3. The variable wheel alignment vehicle of claim 2,

the wheel-position changing mechanism is operatively connected to the suspension device such that all of the wheels are horizontally movable with respect to a center point positioned near a center position of the vehicle body.

4. The variable wheel alignment vehicle of claim 2,

the wheel position changing mechanism is operatively connected to the suspension device such that a wheel moving path forms a single circular path in which all wheels can be horizontally moved with respect to a center point positioned at the vehicle body center position without changing a distance between the center point and the wheels.

5. The variable wheel alignment vehicle of claim 1, wherein

The wheel movement path of the wheel position changing mechanism is configured such that at least one of the wheels is horizontally movable with respect to a center point positioned at a single position of the vehicle, and is movable in a vertical direction of the vehicle in combination with the horizontal movement.

6. The variable wheel alignment vehicle of claim 1, wherein

The wheel position control device is further configured to control the wheel position changing mechanism such that the wheel alignment distance from one of the wheels aligned toward the acceleration direction to the center of gravity becomes greater than the wheel alignment distance from one of the wheels aligned opposite to the acceleration direction to the center of gravity.

7. The variable wheel alignment vehicle of claim 1, wherein

The wheel position control means is further configured to change the wheel position of at least one of the wheels such that the wheel load of the drive wheel of the wheel is larger than the wheel load of the non-drive wheel of the wheel, in accordance with the target wheel load on which the calculation is performed.

8. The variable wheel alignment vehicle of claim 1, wherein

The wheel position control means is further configured to change a wheel position of at least one of the wheels in accordance with a target wheel load calculated based on a target vehicle attitude.

9. The variable wheel alignment vehicle of claim 1, further comprising:

acceleration vector detection means for detecting an acceleration vector of the vehicle in a horizontal plane, wherein the wheel position control means is further configured to change a wheel position of at least one of the wheels in accordance with a direction of the detected acceleration vector.

10. The variable wheel alignment vehicle of claim 9, wherein

The wheel position control means is further configured to divide the wheels into a first group and a second group, the first group being located on one side of the acceleration vector and the second group being located on an opposite side of the acceleration vector, and the wheel position control means is further configured to change the wheel positions of the wheels in accordance with a distance between the wheels of each of the first and second groups.

11. The variable wheel alignment vehicle of claim 1, wherein

The wheel position control means is configured to select one of the wheels as a reference wheel that is kept fixed, and to change the wheel positions of the selected remaining wheels when changing the wheel positions.

12. The variable wheel alignment vehicle of claim 11, wherein

The wheel position control means is configured to select one of the wheels having a larger wheel load than the remaining ones of the wheels as the reference wheel.

13. The variable wheel alignment vehicle of claim 11, wherein

The wheel position control device is configured to select one of the wheels that is closest to the acceleration direction of the center of gravity as the reference wheel.

14. The variable wheel alignment vehicle of claim 1, wherein

The wheel position changing mechanism includes

A suspension frame to support the suspension;

a bearing that supports the suspension frame relative to the vehicle body at an end of the suspension frame opposite to an end that supports the suspension, and supports the suspension frame such that the suspension frame is rotatable relative to the vehicle body; and

an actuator disposed on one of the suspension device and the suspension device frame to move the suspension device relative to the vehicle body.

15. The variable wheel alignment vehicle of claim 1, wherein

The wheel position changing mechanism includes

A slider extending around the vehicle body periphery and supporting the suspension; and

an actuator disposed on the suspension device to move the suspension device relative to the vehicle body.

16. The variable wheel alignment vehicle of claim 1, wherein

The wheel position changing mechanism includes

A suspension frame supporting the suspension and responsive to a retractable member to retract in response to a force applied to the wheel from a road surface;

a bearing that supports the suspension frame relative to the vehicle body at an end of the suspension frame opposite the end that supports the suspension and supports the suspension frame such that the suspension frame rotates relative to the vehicle body;

a slider extending around an outer periphery of the vehicle body and supporting the suspension device;

an actuator provided on one of the suspension device and the suspension device frame to move the suspension device relative to the vehicle body, an

A shock absorber disposed between the slider and the suspension device.

17. The variable wheel alignment vehicle of claim 1, wherein

The suspension device is a double-fork-lever type suspension device; and

the wheel position changing mechanism includes

A first slider extending around an outer periphery of the vehicle body and supporting a lower arm of the suspension device;

a second slider extending around an outer periphery of the vehicle body and supporting an upper arm of the suspension device;

an actuator connected to one of the upper and lower arms of the suspension device to move the suspension device relative to the vehicle body.

18. The variable wheel alignment vehicle of claim 1, wherein

The wheel position changing mechanism includes

A suspension frame supporting the suspension;

a slider provided on the intermediate member and supporting the suspension frame at an end thereof opposite to an end supporting the suspension; and

an actuator disposed on one of the suspension and the suspension frame to move the suspension relative to the intermediate member,

the intermediate member is mounted to the vehicle body with an elastic member interposed therebetween.

19. The variable wheel alignment vehicle of claim 1, wherein

The wheel position changing mechanism includes

A suspension frame supporting the suspension; and

a bearing that supports the suspension frame relative to the vehicle body at an end of the suspension frame opposite to an end that supports the suspension, and supports the suspension frame such that the suspension frame is rotatable relative to the vehicle body;

the bearing is provided at a corner of the vehicle body with respect to each of the wheels.

20. The variable wheel alignment vehicle of claim 19, wherein

The wheel position changing mechanism includes a linear actuator that is mounted to the vehicle body and is connected to the suspension frame at a position away from an end portion of the suspension frame that is supported with respect to the vehicle body.

21. The variable wheel alignment vehicle of claim 1, wherein

The wheel position changing mechanism includes

A first slider extending around an outer periphery of the vehicle body and supporting an upper portion of the suspension device having a first movement path;

a second slider extending around an outer periphery of the vehicle body and supporting a lower portion of the suspension device having a second movement path that is different from the first movement path, an

An actuator disposed on the suspension device to move the suspension device relative to the vehicle body.

22. A variable wheel alignment vehicle comprising:

a body arrangement for forming a vehicle compartment having a center of gravity;

a wheel arrangement for being rotatably mounted relative to the body arrangement;

a wheel-position changing device for moving the wheel device along a moving path with respect to the vehicle-body device and holding the wheel device at any position along the moving path; and

a wheel position control device to control the wheel position changing mechanism to change a wheel positioning distance between a center rotational axis of the wheel device and a center of gravity of the vehicle body device measured in a direction parallel to an acceleration direction of the center of gravity of the vehicle body device, in accordance with a running condition of the vehicle.

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