JP2580851B2 - Caster angle control device for vehicles - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a caster angle control device for a vehicle suspension, and more particularly, to a caster angle for a vehicle capable of controlling a caster angle in accordance with a lateral external force applied to the vehicle. It relates to a control device.

2. Description of the Related Art It is known that the running characteristics of a vehicle can be changed by adjusting the alignment of a suspension in an automobile, and a caster angle (hereinafter simply referred to as a caster) as one of suspension elements is adjusted. Means for improving the running performance of vehicles have also been proposed.

As for such casters, increasing the angle improves the straight running stability and decreasing the angle improves the steering performance.
For example, it has been proposed to improve the straight running performance by controlling the casters to increase as the vehicle speed increases, or to improve the steering performance by controlling the casters to decrease as the steering angle increases. ing.

[Problems to be Solved by the Invention] By the way, when an external force other than the driver's intention, such as a crosswind, acts on the vehicle, especially during high-speed driving, there is a fear that the vehicle body may deviate from an appropriate driving lane. External forces must be dealt with by appropriate steering and accelerator operations.

However, advanced operation techniques are required to quickly and appropriately perform such measures against momentary external forces such as gusts.

Therefore, it is conceivable to cope with such an external force by automatically adjusting the suspension alignment instead of the driver's operation, and the vehicle receives the external force by performing appropriate alignment adjustment in a timely manner with respect to the external force. I want to be able to reduce the burden on the driver at the time.

The present invention has been devised in view of such a problem, and enables a vehicle to appropriately automatically adjust a camber when an external force is applied to a vehicle, so that a driver can use advanced technology even for an external force such as a cross wind. It is an object of the present invention to provide a caster angle control device for a vehicle, in which stable running of the vehicle can be continued without making full use of the vehicle.

[Means for Solving the Problems] Therefore, a caster angle control device for a vehicle according to the present invention includes a caster angle adjusting mechanism capable of adjusting a caster angle in a vehicle suspension by driving a component of the suspension; A vehicle speed detecting means for detecting a vehicle speed of the vehicle, a steering angle detecting means for detecting a steering angle of the vehicle, a lateral external force detecting means for detecting a lateral external force received by the vehicle, and A caster angle setting means for setting an optimum caster angle based on the detection information; and a control means for controlling the caster angle adjusting mechanism so as to take the caster angle set by the caster angle setting means. The angle setting means sets a reference caster angle according to the vehicle speed and the steering angle detected by the vehicle speed detection means and the steering angle detection means. And the lateral external force detected by the lateral external force detecting means during turning such that the steering angle detected by the steering angle detecting means is substantially constant. If so, the reference caster angle is corrected to be large,
When the lateral external force acts on the vehicle toward the outside of the turn, a caster angle external force correction unit for correcting the reference caster angle to be small is provided.

[Operation] In the above-described vehicle caster angle control device of the present invention, the caster angle setting unit is configured to determine the vehicle speed detected by the vehicle speed detecting unit and the steering angle detected by the steering angle detecting unit by the reference caster angle setting unit. Based on the vehicle speed and the steering angle, a reference caster angle is set based on the vehicle angle and the steering angle is substantially constant. When the lateral external force acting on the vehicle is acting on the vehicle toward the inside of the turn, it is corrected to increase the reference caster angle, and when the lateral external force is acting on the vehicle toward the outside of the turn. Is corrected to reduce the reference caster angle. Then, the control means controls the caster angle adjusting mechanism so as to obtain the caster angle set in this manner, and the caster angle adjusting mechanism drives the components of the suspension appropriately to set the caster angle to a predetermined size. It is adjusted to.

[Embodiment] Hereinafter, a vehicle caster angle control device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a flowchart showing the contents of the caster angle control, and FIGS. 6 is an exploded perspective view showing the caster adjusting mechanism, FIG. 7 is a perspective view showing a suspension provided with the caster angle adjusting mechanism, and FIG. FIG. 3 is a hydraulic circuit configuration diagram of an actuator.

First, the suspension of a vehicle equipped with this device will be described. The suspension of this embodiment is a strut type front suspension for a passenger car as shown in FIG. As is well known, a shock absorber 2 and a coil spring 3 are combined, and the head of each strut 1, 1 is fixed to the vehicle body 4 side. A front wheel 7 is rotatably mounted on the lower end of each strut 1, 1 via a knuckle 5 and a hub 6.

The lower end of the strut 1 is connected via a lower arm 8 to a cross member 9 provided between the front wheels so as to also serve as a subframe, and constitutes a suspension using the shock absorber 2 as a part of a suspension link. ing.

Reference numeral 10 denotes a center member provided on the cross member 9, and reference numeral 11 denotes a disc brake.

A caster angle adjustment mechanism (slide) that allows the caster angle to be freely adjusted by sliding the heads 1A, 1A in the front-rear direction of the vehicle body 4 to the mounting portions of the heads 1A, 1A of the struts 1, 1 respectively. Mechanism) 12,12 are provided.

In FIG. 7, 27 is a drive shaft, and 28 is a stabilizer.

Each of the caster angle adjusting mechanisms 12, 12 has the same configuration, and as shown in FIG. 6, a slide base 14 attached to the vehicle body 4 on the upper surface of the strut tower,
A slide plate 13 which is attached to the upper end of the strut 1 and is slidable with respect to the slide base 14 is provided.

The slide base 14, for example, has a structure in which a substantially rectangular through hole 16 parallel to the vehicle longitudinal direction is provided in the center of a plate member 15 whose longitudinal side faces the vehicle longitudinal direction.
A pair of rail portions 17, 17 each having a substantially triangular cross section are provided upright on two sides corresponding to the vehicle width direction side 16 in parallel. Each of the rails 17, 17 is arranged inward, and the head 1A of the strut 1 penetrates between the opposed rails 17, 17 and inside the through hole 16. 17a is a rib for supporting the rail portion 17.

On the other hand, the slider plate 13 is
Substantially rectangular plate member 1 with dimensions corresponding to the distance between 17,17
8 and sliding walls 19, 19 having a wedge shape, which are provided on the entire two parallel sides of the plate member 18 on the rail side and which can be inserted into the rails 17, 17.

The sliding wall portions 19, 19 have a wedge-shaped cross section, for example, the plate member 1
A symmetrical triangular wall with the side of 8 as the top is integrally provided on the side of the plate member 18 and slides on the rails 17, 17 without rattling, whereby the slide plate
The rail 13 is guided by the rails 17, 17 between the rails 17, 17 and can slide in a certain direction.

In addition, between each sliding wall portion 19 and the rail portion 17 facing the same, for example, a needle roller bearing 20 in which a plurality of roller bearings are arranged in parallel is interposed along the sliding direction, and the slider plate 13 is Stable and smooth sliding along the direction. In FIG. 6, reference numeral 21 denotes a bearing rolling surface provided on each of four outer surfaces of the sliding wall portion 19, and is formed of a rectangular recess.

The upper end of the strut 1 penetrates through the slide base 14 and is inserted into a circular opening 13a provided at the center of the slide plate 13. Also, fixed holes are provided before and after the opening 13a.
On the other hand, a pair (two) of mounting bolts 23, 2 is provided on the head portion 1A of the strut 1, for example, on the insulator portion 1a.
3 are projected, and these fixing bolts 23,2 are
By fastening 3, the head 1 </ b> A of the strut 1 is integrated with the slider plate 13. Thus, the casters of the front suspension can be made variable by sliding the slider plate 13 in the front-rear direction.
Numeral 24 indicates a nut for fastening the strut head.

And each slide plate 1 of such a slide mechanism 12,12
An actuator (drive device) 25 for moving the strut head in the longitudinal direction of the vehicle body is directly connected to 3. As the actuator 25, for example, a hydraulic actuator that drives a hydraulic cylinder 25B through a hydraulic supply / discharge system 25A having a hydraulic switching valve such as an electromagnetic valve as illustrated is conceivable.

In this case, for example, a hydraulic circuit configuration as shown in FIG. 8 is conceivable. In FIG. 8, 25a is a tank for storing hydraulic oil, 25b is a pump, 25c is a pump accumulator,
25d and 25e are main accumulator, 25f is filter, 25g
Is a relief valve, 25h is a check valve, 25i, 25j, 25
k and 25l are control valves, 25m and 25n are position sensors, and other symbols are the same as those described above.

A controller (comprising a microcomputer and its peripheral circuits) 26 as a control means is connected to the actuator 25, and various sensors (for example, a vehicle speed sensor, a steering angle sensor, and a lateral acceleration sensor) taken into the controller 26 are provided. based on the information from the 29, and to allow variable angle of caster in accordance with the magnitude of the vehicle speed V and the steering angle θ and the lateral acceleration G _Y.

In particular, the controller 26 includes a caster angle setting unit that sets an optimum caster angle based on detection information from each sensor, and a caster angle adjustment mechanism that takes the caster angle set by the caster angle setting unit. It has a control unit to control.

The caster angle setting section includes a reference caster angle setting section and a caster angle external force correction section. In the reference caster angle setting section, a reference caster angle corresponding to the vehicle speed and the steering angle is set. Then, correction is performed when the vehicle turns while the steering angle is almost constant.At this time, if the lateral external force increases, the correction is made to increase the reference caster angle, and the lateral external force may decrease. For example, correction is made so as to reduce the reference caster angle.

By the way, the value C of the caster angle (caster) is as follows: C = C ₀ + KV · Kθ · C ₀ ′ · KX (1) where KV = vehicle speed correction coefficient Kθ = steering angle correction coefficient KX = external force correction coefficient C ₀ = Caster auxiliary setting value C ₀ '= correction auxiliary setting value The vehicle speed correction coefficient KV is a coefficient that increases in accordance with the increase in the vehicle speed V as shown in FIG. 2, and the steering angle correction coefficient Kθ is the steering angle θ as shown in FIG.
The external force correction coefficient KX
As shown in FIG. 4, when the lateral acceleration G _Y acting on the vehicle is from the outside of the turn in the turning direction, the lateral acceleration G _Y increases from the turning direction to the outside of the turn. Is a coefficient that decreases according to its size.

The reference caster angle setting unit obtains a vehicle speed correction coefficient KV from the detected value V of the vehicle speed sensor based on the vehicle speed correction coefficient map (see FIG. 2), and obtains a steering angle correction coefficient map (see FIG. 3).
The steering angle correction coefficient Kθ is obtained from the detected value θ of the steering angle sensor based on the above, and these values KV, Kθ are integrated into a correction auxiliary set value C ₀ ′ which is a preset value, and this is caster auxiliary set value. By adding to C ₀ , the value C of the caster (reference caster) is set.

If the vehicle is not turning, the caster C (= C ₀ + KV · Kθ ·) set by the reference caster angle setting unit
C ₀ ′) is the target caster, but when an external force such as a cross wind acts on the vehicle during turning of the vehicle, the caster angle external force correction unit corrects the external force with the external force correction coefficient KX corresponding to the external force. C (= C ₀ + KV · Kθ · C ₀ ′ · KX) is configured to be the target caster.

Since the caster angle control device for a vehicle according to one embodiment of the present invention is configured as described above, the caster angle control is performed as shown in FIG.

That is, first, the like immediately after the ignition switch is turned on the motor vehicle, the parameters relating to the control initially set (step S1), the vehicle speed V, the reads the steering angle θ and the lateral acceleration G _Y from each sensor (step S1).

The reference caster C (= C ₀ + KV · Kθ ·) is set in each of the reference caster setting units based on the vehicle speed correction coefficient KV corresponding to the vehicle speed V and the steering correction coefficient Kθ corresponding to the steering value θ.
C ₀ ′) is set (step S3).

Furthermore, the magnitude of the steering angle theta | theta | is determined whether less than a predetermined amount theta ₀ (step S4), | θ | is theta ₀
If it is smaller, it is determined that the vehicle is traveling straight, and the above-described reference caster C (= C ₀ + KV · Kθ · C ₀ ′) is set as the target caster.

If | θ | is larger than θ ₀ , the process proceeds to step S5 to determine whether the steering angular velocity is 0, that is, whether the steering angle θ is constant.

If the steering angle θ is not constant, no special correction is performed on the reference caster. However, if the steering angle θ is constant, the process proceeds to an external force correction route for controlling the casters in accordance with a lateral external force applied to the vehicle body such as a crosswind.

That is, first, the process proceeds to step S6 to perform correction (acceleration correction). This correction is lateral acceleration of the vehicle when performing acceleration or deceleration during turning is changed, those from the lateral acceleration G _Y detected by the lateral acceleration sensor from the time variation of the base circle lateral acceleration to cancel the acceleration component It is. Further, since the time change of the lateral acceleration due to the acceleration / deceleration is obtained from the vehicle speed data V and the steering angle data θ, in step S6, the change in the lateral acceleration due to the acceleration / deceleration is calculated.
It can be performed acceleration correction by excluding the time variation of the lateral acceleration due to deceleration from the time variation of the detected lateral acceleration G _Y.

Then, in the subsequent step S7, as in this way to determine whether the time variation amount _Y of the lateral acceleration G _Y that has been subjected to correction is 0, the horizontal direction external force if the value is 0 is not applied No external force correction is performed.

On the other hand, if the value _Y is not 0, it is assumed that a lateral external force is acting and external force correction is performed.

In this external force correction, first, in step S8, it is determined whether the lateral acceleration change amount _GY is positive or negative, that is, whether the lateral acceleration _Y is increasing or decreasing, and the large caster correction (step S9) is performed accordingly. ) Or small caster correction (step S10)
Perform Incidentally, the lateral acceleration G _Y is a turning direction is a positive direction.

That is, if the lateral acceleration G _Y increases in the turning direction, the external force acts inward of the turn, and at this time, a large external force correction coefficient KX is adopted according to the increase amount ( If the lateral acceleration _GY decreases in the turning direction, the external force is working outward, so at this time, A small external force correction coefficient KX is adopted in accordance with the decrease amount (see the left half of FIG. 5), and the caster is corrected to be small.

Caster C (= C ₀ + KV ·
Kθ · C ₀ ′ · KX) is set as the target caster.

Then, the controller 26 controls the actuator 25 so that the actual caster becomes the caster C thus set, and the actuator plates 25 drive the respective slider plates 13 and 13 forward or rearward. Adjusted.

As a result, when an external force acts while turning at a substantially constant steering angle, the casters are increased when the external force acts in a direction that urges turning (inward turning), so that excessive turning is prevented. When running stability is secured and external force is acting in the direction that hinders turning (ie, outside of turning),
Since the number of casters is reduced, turning performance is enhanced.

Such automatic adjustment of the camber enables the driver to stably drive the vehicle even with external force such as a cross wind without using advanced technology.

The application of the caster angle control device is not limited to the suspension and the caster angle adjusting mechanism (slide mechanism) 12 having the configuration as in the present embodiment, but may be applied to the caster angle external force correction as described above. For example, the present invention is widely applicable to other configurations.

[Effects of the Invention] As described in detail above, according to the vehicle caster angle control device of the present invention, in a vehicle suspension, a caster angle adjustment mechanism capable of adjusting a caster angle by driving a component of the suspension. Vehicle speed detecting means for detecting a vehicle speed of the vehicle, steering angle detecting means for detecting a steering angle of the vehicle, lateral external force detecting means for detecting a lateral external force received by the vehicle, and each of these detecting means A caster angle setting means for setting an optimum caster angle based on the detection information from the control means, and a control means for controlling the caster angle adjusting mechanism so as to take the caster angle set by the caster angle setting means. The caster angle setting means sets a reference caster angle according to the vehicle speed and the steering angle detected by the vehicle speed detecting means and the steering angle detecting means. The setting unit and the lateral external force detected by the lateral external force detecting means during the turning such that the steering angle detected by the steering angle detecting means is substantially constant acts on the vehicle inward while turning. The caster angle external force is corrected so as to increase the reference caster angle if it is present, and is corrected so as to reduce the reference caster angle if the lateral external force is acting on the vehicle outward from the turn. With a configuration that includes a correction unit, the caster angle is automatically adjusted appropriately when the vehicle is subjected to external force, and the vehicle continues to run stably without external force such as crosswind without the driver using advanced technology become able to.

[Brief description of the drawings]

1 to 8 show a caster angle control device for a vehicle as an embodiment of the present invention. FIG. 1 is a flowchart showing the contents of the caster angle control, and FIGS. Graph showing the characteristics of the coefficient according to the setting of
6 is an exploded perspective view showing the caster angle adjusting mechanism, FIG. 7 is a perspective view showing a suspension having the caster angle adjusting mechanism, and FIG. 8 is a hydraulic circuit configuration diagram of the actuator. 1 ... Strut, 1A ... Head of strut 1, 1a ...
Insulator part, 2 ... Shock absorber, 3 ...
... Coil spring, 4 ... Vehicle, 5 ... Knuckle, 6
… Hub, 7… Front wheel, 8… Lower arm, 9… Cross member, 10… Center member, 11… Disc brake, 12… Caster angle adjustment mechanism (slide mechanism),
13 ... slide plate, 13a ... opening, 14 ... slide base, 15 ... plate member, 16 ... through hole, 17 ... rail part, 17
a ... rail part, 18 ... plate member, 19 ... sliding wall part, 20 ...
... Needle roller bearing, 22 ... Fixed hole, 23 ... Mounting bolt, 24 ... Nut, 25 ... Actuator (drive unit), 25A ... Hydraulic supply / discharge system, 25B ... Hydraulic cylinder, 25a
…… Tank, 25b …… Pump, 25c …… Pump accumulator, 25d, 25e …… Main accumulator, 25f …… Filter, 25g …… Relief valve, 25h …… Check valve, 25i, 25j, 25k, 25l …… Control Valve, 25m, 25n
... Position sensors, 26 ... Controllers, 27 ... Drive shafts, 28 ... Stabilizers, 29 ... Various sensors (for example, vehicle speed sensors, steering angle sensors, and lateral acceleration sensors).

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Takao Morita 5-33-8 Shiba, Minato-ku, Tokyo Inside Mitsubishi Motors Corporation (56) References JP-A-62-125907 (JP, A) 61-78705 (JP, U)

Claims (1)

(57) [Claims] 1. A vehicle suspension, comprising: a caster angle adjusting mechanism capable of adjusting a caster angle by driving a component of the suspension; vehicle speed detecting means for detecting a vehicle speed of the vehicle; Steering angle detecting means for detecting, lateral external force detecting means for detecting a lateral external force received by the vehicle, caster angle setting means for setting an optimal caster angle based on detection information from each of these detecting means, Control means for controlling the caster angle adjusting mechanism so as to take the caster angle set by the caster angle setting means, wherein the caster angle setting means is detected by the vehicle speed detecting means and the steering angle detecting means. A reference caster angle setting unit for setting a reference caster angle in accordance with the vehicle speed and the steering angle, and a steering angle detected by the steering angle detecting means substantially equal to one. If the lateral external force detected by the lateral external force detecting means is acting on the vehicle inward during the turn such that the reference caster angle is increased, the reference caster angle is increased. A caster angle for a vehicle, comprising: a caster angle external force correction unit that corrects the reference caster angle so as to reduce the reference caster angle when a lateral external force acts on the vehicle outward from the turn. Control device.