JPH0834221A - Setting method for variation characteristic of toe angle of vehicle suspension and suspension used for its execution - Google Patents

Abstract

PURPOSE:To excellently maintain the rectilinear advancing ability of a vehicle even if a tire supported through a vehicle suspension moves vertically during the rectilinear running of the vehicle. CONSTITUTION:In setting the characteristic of the variation of a toe angle caused by the vertical movement of a tire to a car body of a vehicle suspension, the characteristic of the variation of the towing angle is set up so that the toe angle may vary with the vertical movement of the tire so as to cancel the change of the cornering force of the tire based on the change DELTAW of a tire load due to the vertical movement of the tire to the car body during the running of a vehicle by the change of the cornering force of the tire based on the change DELTASA of a slip angle due to the change of the toe angle of the tire.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for setting a characteristic of a toe angle change of a vehicle suspension due to a vertical movement of a tire with respect to a vehicle body, and a vehicle suspension that can be used for implementing the method.

[0002]

2. Description of the Related Art A vehicle in a so-called straight running state is not actually traveling in front of the vehicle because each tire is oriented parallel to the longitudinal axis of the vehicle, but is applied to each tire. It is well known that the cornering force generated on each tire due to the wheel alignment is traveling in a certain direction that balances the entire vehicle. Dynamic) or rebound (downward), the load applied to the tire increases or decreases, and the increase or decrease in the load also increases or decreases the cornering force of the tire. The sex will be disturbed.

On the other hand, a suspension for a vehicle may change its toe angle due to bumps and rebounds of a tire while the vehicle is running due to the type of the suspension. For example, a double wishbone suspension is generally used. So, basically, a constant toe angle is maintained regardless of the tire bump and rebound to maintain the neutral steer state, but in the semi-trialing arm type rear suspension, the tire bumps and rebounds while the vehicle is running. It has a toe angle change characteristic in which the toe angle changes in the toe-out direction when the tire bumps and in the toe-in direction when the tire rebounds. The change in the toe angle also changes the slip angle of the tire, which changes the cornering force.

Since the toe angle change characteristic is based on the suspension geometry with respect to the vehicle body, it is usually constant and peculiar to the vehicle suspension.
Some conventional vehicle suspensions positively change the original toe angle change characteristics of the rear wheels, in particular, by operating the actuator in order to obtain a desired turning characteristic.

The change in the toe angle of a conventional vehicle suspension is not associated with the bumping or rebound of the tire with respect to the vehicle body, but the braking force applied to the tire during braking or turning of the vehicle and the elastic bushing of the suspension due to the cornering force. There is also a case where it occurs as so-called compliance steer due to the deformation of.

[0006]

However, in all of the conventional vehicle suspensions, the above-mentioned vehicle body suspension has the increase and decrease in the cornering force due to the tire load increase and decrease due to the tire pump and rebound with respect to the vehicle body described above. Since the relationship with the change in cornering force due to the change in slip angle due to the change in toe angle due to tire pumping and rebound was not considered, the increase or decrease in cornering force due to the increase or decrease in load and the increase or decrease in cornering force due to the change in toe angle Will not be sufficient if they act in mutually reinforcing directions, or happen to cancel each other out, and therefore either tire bumps or bumps during straight running of the vehicle. The problem that the straightness of the vehicle is disturbed when rebounding There were present.

[0007]

SUMMARY OF THE INVENTION The present invention provides a method for setting a toe angle change characteristic of a vehicle suspension that advantageously solves the above-mentioned problems of the prior art, and a vehicle suspension that can be used for implementing the method. The toe angle change characteristic setting method for a vehicle suspension according to the present invention, when setting the characteristic of the toe angle change associated with the vertical movement of the tire with respect to the vehicle body of the vehicle suspension, the vertical movement of the tire with respect to the vehicle body while the vehicle is running. Along with the vertical movement of the tire, the variation of the cornering force of the tire based on the variation of the load of the tire is canceled by the variation of the cornering force of the tire based on the variation of the slip angle due to the variation of the toe angle of the tire. The characteristics of the toe angle change are set so that the toe angle changes. It is an.

According to the present invention, in the setting method, when the vehicle is being braked, the toe angle of the vehicle suspension is maintained at the toe-out while the vehicle suspension is for the front wheels regardless of the vertical movement of the tire with respect to the vehicle body. When the vehicle suspension is for the rear wheels, the characteristic of the toe angle change may be set so that the toe angle is maintained at the toe-in.

On the other hand, the vehicle suspension of the present invention includes a suspension unit that supports a tire so as to be able to move up and down with respect to a vehicle body and that has a suspension unit that can cause a change in the toe angle as the tire moves up and down. In the suspension, the suspension unit changes the cornering force of the tire based on the change in the load of the tire due to the vertical movement of the tire with respect to the vehicle while the vehicle is running, due to the change in the toe angle of the tire. It is characterized by having a suspension geometry such that the toe angle changes with the vertical movement of the tire so as to be canceled by a change in the cornering force of the tire based on a change in the slip angle.

According to the present invention, the vehicle suspension is configured such that the suspension unit is constructed by vertically moving the tire with respect to the vehicle body while the vehicle is traveling around a rotation axis extending in the lateral direction of the vehicle body. The toe with the vertical movement of the tire so that the change in the cornering force of the tire due to the change in the load of the tire is canceled by the change in the cornering force of the tire due to the change in the slip angle due to the change in the toe angle of the tire. The toe-out is maintained at the toe-out position when the suspension for the front wheel of the vehicle suspension is used regardless of the disturbance canceling position of the suspension unit with a suspension geometry such that the angle changes and the vertical movement of the tire with respect to the vehicle body. On the other hand, if the vehicle suspension is for rear wheels, Suspension unit rotating means for rotating the suspension geometry for changing the toe angle of the toe-in with respect to the vehicle body between the suspension geometry and the posture stable position of the suspension unit, and the suspension. By controlling the operation of the unit rotating means, while the vehicle is traveling straight ahead, the suspension unit is located at the disturbance canceling position except during braking of the vehicle, while the suspension unit is operated during braking of the vehicle. The suspension unit rotation control means for positioning the posture stable position may be provided.

[0011]

According to the first method of the present invention, when setting the characteristics of the toe angle change of the vehicle suspension due to the vertical movement of the tire with respect to the vehicle body, as shown in FIGS. 6 (a) and 6 (b), A tire based on a change ΔW in load W of the tire due to vertical movement of the tire with respect to the vehicle body while the vehicle is running, a change in cornering force CF of the tire based on a change ΔSA in slip angle SA due to a change in the toe angle of the tire Since the characteristics of the toe angle change are set so that the toe angle changes with the vertical movement of the tire so as to be canceled by the change in the cornering force CF, the increase or decrease of the cornering force due to the increase or decrease of the load is changed to the toe angle. If the cornering force is increased or decreased due to the change, it can be sufficiently canceled and the suspension for the vehicle supports it while the vehicle is running straight. The straightness of the vehicle can be maintained extremely excellent even if some tire bumps or rebounds.

According to a second method of the present invention, in the first method, when the vehicle is being braked, the toe of the front suspension is applied to the vehicle suspension regardless of the vertical movement of the tire with respect to the vehicle body. The characteristics of the toe angle change are set so that the toe-out angle is maintained at the toe-in while the vehicle suspension is for the rear wheels while the toe-out angle is maintained at the toe-out. Keeps the front wheels, which tend to have negative camber angles, toe-out, or the rear wheels, which tend to have positive camber angles due to rebound due to a decrease in load, keeps toe-in, canceling the canvas last and stabilizing the direction. Since it is possible to increase the
The straightness of the vehicle can be maintained extremely excellent not only during normal traveling but also during braking.

On the other hand, the first vehicular suspension of the present invention comprises a suspension unit that supports the tire so as to be able to move up and down with respect to the vehicle body, and that causes a change in the toe angle as the tire moves up and down. In such a suspension for a vehicle, a change in cornering force of the tire based on a change in load of the tire due to vertical movement of the tire relative to the vehicle while the vehicle is traveling is The suspension geometry has such a change that the toe angle changes with the vertical movement of the tire so as to be canceled by the change in the cornering force of the tire based on the change in the slip angle due to the change in the slip angle. Method 1 and therefore as described above. Can either tire vehicular suspension during straight traveling of the vehicle to support is very well maintained straightness of the vehicle even when the bumps or rebounds.

A second vehicle suspension according to the present invention is the suspension for a vehicle according to the first vehicle, wherein the suspension unit is installed while the vehicle is traveling around a rotation axis extending in a lateral direction of the vehicle body. The variation of the cornering force of the tire based on the variation of the load of the tire due to the vertical movement of the tire with respect to the vehicle body is canceled by the variation of the cornering force of the tire based on the variation of the slip angle due to the variation of the toe angle of the tire. The suspension canceling position of the suspension unit has a suspension geometry such that the toe angle changes with the vertical movement of the tire, and the vehicle suspension is for the front wheels regardless of the vertical movement of the tire with respect to the vehicle body. If the toe angle is kept toe-out, When the dual-use suspension is for rear wheels, the suspension geometry for changing the toe angle that maintains the toe angle at the toe-in is rotated with respect to the vehicle body between the suspension unit and the posture stable position of the suspension unit. The suspension unit rotating means and the operation of the suspension unit rotating means are controlled to position the suspension unit at the disturbance canceling position while the vehicle is traveling straight ahead, except during braking of the vehicle. The suspension unit rotation control means for positioning the suspension unit at the posture stable position during braking is used to perform the second method of the present invention described above. Therefore, as described above, The straightness of the vehicle not only during normal running but also during braking as well as during normal running It can be very satisfactorily maintained.

[0015]

Embodiments of the present invention will be described in detail below with reference to the drawings. Here, FIG. 1 is a front view of an embodiment in which a vehicle suspension according to the present invention is applied to a front-wheel-drive rear-wheel vehicle suspension as viewed from the side of a vehicle body, and FIG. FIG. 3 is a plan view of the vehicle suspension as seen from above the vehicle body of the automobile, and FIG. 3 is a side view of the vehicle suspension as seen from the front of the vehicle body of the embodiment. In FIG. ) 2 is a tire (rear wheel), 3 is a suspension unit, and 4 is a suspension canceling position and posture described later around an axis C extending the suspension unit 3 in the lateral direction of the vehicle body (horizontal direction in FIGS. 2 and 3). A unit rotating mechanism as a suspension unit rotating means for rotating between the stable position and a suspension unit for controlling the operation of the unit rotating mechanism 4. Shows the unit rotation control apparatus as Tsu preparative rotation control means, respectively, also arrow F in the figure, shows a vehicle forward direction. Although the illustrated example shows only the left rear wheel suspension, the right rear wheel suspension is similarly configured.

The suspension unit 3 in this embodiment extends in the vehicle body vertical direction (vertical direction in FIGS. 1 and 3) through a plane of symmetry of the vehicle body 1 (a central axis (X axis) extending in the vehicle front-rear direction). Support surface that is inclined with respect to the imaginary plane (the suspension unit 3 faces diagonally rearward of the vehicle when the suspension unit 3 is in the disturbance canceling position shown in the drawing).
A base 6 having 6a, a hub 7 for rotatably pivoting the tire 2 by an axle 7a protruding in the lateral direction of the vehicle body, and both ends thereof swingable between the support surface 6a of the base 6 and the hub 7. Two upper links 8 and 9 and two lower links 10 and 11 connected to each other, an upper beam 12 integrally connecting the two upper links 8 and 9, and both ends of the upper beam 12 at the center of the upper beam 12. The double wishbone suspension is configured by including a spring 13 with an oil damper that is swingably connected to the upper portion and the upper protruding portion 6b of the base portion 6.

Here, of the two upper links 8 and 9 and the two lower links 10 and 11, the upper link 8 and the lower link 10 located on the front side of the vehicle body are located on the rear side of the vehicle body. The upper link 9 and the lower link 11 are made shorter and are arranged at a slightly higher position, and the length difference between the upper link 8 and the upper link 9 and the lower link 10 and the lower link 11 are different from each other. Of the length of the support surface 6a
As a result, the suspension unit 3 is placed on the tire 2 in the disturbance canceling position shown in the figure and the vehicle is stopped on the horizontal road surface 14 in the toe-in direction as shown in FIG. A given initial value for the angle α is given.

Further, as shown in FIG. 4, the unit rotating mechanism 4 in this embodiment is interposed between the base 6 and the vehicle body 1 to rotate the base 6 around the axis C in the lateral direction of the vehicle body. A bearing 15 that supports the vehicle body 1 as much as possible, a worm wheel 16 coaxially arranged with the axis C on the inner side of the vehicle body of the base portion 6 and integrally coupled to the base portion 6, and a worm wheel 16 that meshes with the worm wheel 16. And a stepping motor 18 for rotating the worm gear 17. The unit rotating mechanism 4 includes a stepping motor 18 for rotating the worm gear 17.
By activating, the worm gear 17 and the worm wheel 16 can be used to rotate the base 6 and thus the suspension unit 3 as a whole about the axis C to an arbitrary rotation position.

The unit rotation control device 5 in this embodiment, as shown in FIG. 5, is a normal acceleration sensor 19 for detecting the longitudinal and lateral accelerations of the vehicle body 1.
And a processor that can be configured by a normal microcomputer that receives a signal from the acceleration sensor 19 and appropriately operates the stepping motor 18 based on the signal.
When the processor 20 of the unit rotation control device 5 determines from the signal from the acceleration sensor 19 that the vehicle is traveling in a normal straight state including acceleration, the stepping motor 18 is provided. Is operated to position the suspension unit 3 at the disturbance canceling position shown in the figure, and when it is determined by the signal from the acceleration sensor 19 that the vehicle is traveling straight ahead and is being braked, stepping is performed. By appropriately operating the motor 18, the suspension unit 3 is positioned at a posture stable position (not shown) which is appropriately rotated counterclockwise in FIG. 1 from the disturbance canceling position shown. Here, since the transmission system including the worm gear 17 and the worm wheel 16 is inserted, the suspension unit 3 is not rotated by the operation of the stepping motor 18 even if another external force is applied to the suspension unit 3 from the tire 2 or the like. As long as possible, the disturbance canceling position or the posture stable position is maintained.

However, when the suspension unit 3 is located at the disturbance canceling position because the vehicle is traveling straight ahead normally, the difference in length between the upper link 8 and the upper link 9 and the lower link 10 are caused. When the tire 2 bumps (moves upward) due to the difference in the length between the lower link 11 and the lower link 11 and the inclined state of the support surface 6a facing diagonally rearward of the vehicle, the angle formed between the tire 2 and the support surface 6a. Decrease and the toe angle α decreases from the initial value, and when the tire 2 rebounds (moves downward), the tire 2 and the supporting surface 6a
And the toe angle α increases from the initial value. In this embodiment, utilizing the change in the toe angle α,
The tire is obtained by appropriately selecting the inclination angle of the support surface 6a and the lengths of the upper links 8 and 9 and the lower links 10 and 11 which are correspondingly provided with the difference and bring the initial value of the toe angle α. 2 shows a variation Δ in the load W of the tire 2 due to bumps or rebounds of the tire 2 as shown in FIG.
A change in the cornering force CF of the tire 2 based on W is a change in the slip angle SA due to a change in the toe angle α of the tire 2 A cornering force CF of the tire 2 based on ΔSA
The toe angle α is changed so as to be canceled by the fluctuation of.

Therefore, according to the rear wheel suspension of this embodiment, even if the tire 2 supported by the suspension bumps or rebounds while the vehicle is running straight, the straight running performance of the vehicle is maintained extremely excellent. be able to.

On the other hand, since the automobile is traveling straight ahead and braking, the suspension unit 3 is
From the disturbance canceling position, in the counterclockwise direction in FIG.
Appropriately rotated within a range that does not hinder the smooth vertical movement of the vehicle, in the state of being positioned in the posture stable position, the inclined state of the support surface 6a, from the state of facing the oblique rear of the vehicle, Since the vehicle is turned obliquely upward and obliquely rearward, the angle between the X axis and the supporting surface 6a is reduced, and the amount of change in the toe angle α due to the bump or rebound of the tire 2 is reduced. , The suspension unit 3 is smaller than that in the disturbance canceling position, and by utilizing the decrease in the variation of the toe angle α in this embodiment, the toe angle α is irrespective of the bump or rebound of the tire 2. Changes the toe angle to maintain the toe-in direction.

Therefore, according to the rear wheel suspension of this embodiment, the straightness of the vehicle can be maintained extremely excellent not only during normal traveling but also during normal traveling as well as during braking.

Although the present invention has been described above based on the illustrated example, the present invention is not limited to the above-mentioned example. For example, the present invention can be applied to a front wheel suspension, and the above-described operational effects can be obtained. Also, the suspension type is not limited to the double wishbone type of the above example, but can be applied to, for example, a semi-trailing type, and the rotation axis of the suspension unit also extends substantially in the lateral direction of the vehicle body. Those skilled in the art will easily understand that the suspension unit may be rotated around a rotation axis extending obliquely rearward, for example. Further, in the above embodiment, only the operation during straight running is described, but in the suspension of the present invention, the processor 20 allows the stepping motor 18 to operate even during turning.
Can be appropriately operated to appropriately change the change characteristics of the toe angle α of the tires on the inner wheel side and the outer wheel side with respect to the turning direction.

[0025]

As described above, according to the first method of setting the toe angle change characteristic of the vehicle suspension of the present invention, any of the tires supported by the vehicle suspension bumps or rebounds while the vehicle is running straight. However, the straightness of the vehicle can be maintained extremely excellently, and according to the second method of the present invention, the straightness of the vehicle can be maintained not only during the straight running of the vehicle but also during the normal running as well as the braking. It can be maintained very well.

On the other hand, according to the first suspension of the vehicle suspension of the present invention, it is possible to carry out the above-mentioned first method of the present invention, and any one of which the vehicle suspension supports while the vehicle is traveling straight ahead. It is possible to maintain the straightness of the vehicle extremely well even if the tire of No. 1 bumps or rebounds, and according to the second suspension of the present invention, it is possible to carry out the above-mentioned second method of the present invention. The straightness of the vehicle can be maintained extremely excellent not only during normal traveling of the vehicle but also during braking as well as during normal traveling.

[Brief description of drawings]

FIG. 1 is a front view of an embodiment in which a vehicle suspension according to the present invention is applied to a front-wheel-drive rear-wheel suspension of a vehicle as viewed from the side of a vehicle body.

FIG. 2 is a plan view of the suspension of the above embodiment as seen from above the vehicle body of an automobile.

FIG. 3 is a side view of the suspension of the above embodiment as seen from the front of the vehicle body of an automobile.

FIG. 4 is a cross-sectional view showing a unit rotation mechanism of the suspension of the above embodiment.

FIG. 5 is a cross-sectional view showing a unit rotation control device of the suspension of the above embodiment.

FIG. 6 is a relationship diagram showing the method of setting the toe angle change characteristic of the vehicle suspension of the present invention in the correlation between the tire slip angle, the cornering force, and the load, and the basic principle of the vehicle suspension of the present invention.

[Explanation of symbols]

 1 vehicle body 2 tire 3 suspension unit 4 unit rotation mechanism 5 unit rotation control device

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Claims (4)

[Claims] 1. When setting a characteristic of a toe angle change of a vehicle suspension due to a vertical movement of a tire with respect to a vehicle body, the tire is based on a variation of a load of the tire due to a vertical movement of the tire with respect to a vehicle body while the vehicle is running. So that the toe angle changes with the vertical movement of the tire so that the change in the cornering force of the tire is canceled by the change in the cornering force of the tire based on the change in the slip angle due to the change in the toe angle of the tire. A toe angle change characteristic setting method for a vehicle suspension, comprising setting a characteristic of a toe angle change. 2. When the vehicle is being braked, the toe angle of the vehicle suspension is maintained at the toe-out when the vehicle suspension is for the front wheels regardless of the vertical movement of the tire with respect to the vehicle body, while the vehicle suspension is for the rear wheels. The toe angle change characteristic setting method for a vehicle suspension according to claim 1, wherein the characteristic of the toe angle change is set so as to maintain the toe angle at the toe-in. 3. A vehicle comprising a suspension unit (3) for supporting a tire (2) so as to be able to move up and down relative to a vehicle body (1) and for causing a toe angle change with the up and down movement of the tire. In the suspension for a vehicle, a change in cornering force of the tire based on a change in a load of the tire due to a vertical movement of the tire with respect to the vehicle body while the vehicle is traveling is caused by a change in a toe angle of the tire. A suspension for a vehicle having a suspension geometry such that the toe angle changes with the vertical movement of the tire so as to be canceled by a change in the cornering force of the tire based on a change in the slip angle. 4. The vehicle suspension is configured so that the suspension unit (3) moves up and down of the tire with respect to the vehicle body while the vehicle is traveling around a rotation axis (C) extending in a lateral direction of the vehicle body. Along with the vertical movement of the tire, the variation of the cornering force of the tire due to the variation of the load of the tire due to the variation of the cornering force of the tire due to the variation of the slip angle due to the variation of the toe angle of the tire is canceled If the suspension for the front wheel of the vehicle suspension is used regardless of the disturbance canceling position of the suspension unit that has a suspension geometry such that the toe angle changes, and the vertical movement of the tire with respect to the vehicle body. If the vehicle suspension is for the rear wheels while maintaining the toe-out, A suspension unit rotating means (4) for rotating the suspension geometry for changing the toe angle so as to keep the angle at the toe-in with respect to the vehicle body between the suspension geometry and the posture stable position of the suspension unit; By controlling the operation of the suspension unit rotating means, while the vehicle is traveling straight ahead, the suspension unit is positioned at the disturbance canceling position except during braking of the vehicle, while the suspension unit is maintained during braking of the vehicle. The vehicle suspension according to claim 3, further comprising: a suspension unit rotation control means (5) which is located at the posture stable position.