JPH0485181A - Caster angle controller for vehicle - Google Patents

Abstract

PURPOSE:To check a vibration in a vehicle by controlling a caster angle adjusting mechanism so as to adopt such a caster angle as reducing the vehicle vibration on the basis of information out of a vibration detecting means, at time of vehicle stoppage. CONSTITUTION:A caster angle adjusting mechanism 12 is provided with a slide base 14 attached to the side of a car body 4 on top of a strut tower and a slide plate 13 being attached to the upper end of a strut 1 and slidable on the slide base 14, and it makes this slide plate 13 slide in the longitudinal direction, through which a caster of a front suspension is made variable, while an actuator 25 for shifting a strut head part in the longitudinal direction of the car body is connected to the slide plate 13. A controller 26 alters a caster angle when strength ¦g¦ of body rocking (seat lower part vibration) becomes larger than the threshold value K, on the basis of detecting information out of a rocking sensor 29, thereby controlling the actuator 25 for the caster angle adjusting mechanism 12 so as to reduce the body vibration.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a caster angle control device in a vehicle suspension, and particularly to a caster angle control device for suppressing vehicle vibration. The present invention relates to a caster angle control device for a vehicle.

[Prior Art] It is known that the driving characteristics of a vehicle can be changed by adjusting the suspension alignment of an automobile, and the caster angle (hereinafter also simply referred to as caster), which is one of the suspension elements, can be adjusted. Means for improving the driving performance of a vehicle has also been proposed.

Regarding such casters, increasing the angle improves straight-line stability, and decreasing the angle improves steering performance. For example, it is possible to improve straight-line performance by controlling the casters to become larger as the vehicle speed increases. It has been proposed to improve steering performance by controlling the caster to become smaller as the steering angle becomes larger.

[Problems to be Solved by the Invention] In automobiles, preventing vibrations not only when driving but also when stopped is a major issue. Such vibrations are caused by engine vibrations and suspension vibrations that cause damage to the body and interior of the body. This is likely to occur due to resonance with other objects (particularly seats, etc.), and changing the vibration characteristics (natural frequency) on the side of these vibrations can be a fundamental solution to vehicle vibration. In particular, since the vibration characteristics of the suspension can be changed by alignment adjustment, it is expected that alignment adjustment will suppress vehicle body vibration.

The present invention was devised in view of such problems, and
It is an object of the present invention to provide a caster angle control device for a vehicle, which is capable of suppressing vibrations by changing a camber angle, which is a suspension alignment element, when vibrations occur in the vehicle.

[Means for Solving the Problems] Therefore, the caster angle control device for a vehicle of the present invention includes a caster angle adjustment mechanism that can adjust the caster angle by driving the components of the suspension in the suspension of the vehicle; a control means for controlling the caster angle adjustment mechanism, and a vibration detection means for detecting vibrations of the vehicle, and the control means detects vibrations of the vehicle based on information from the vibration detection means when the vehicle is stopped. The present invention is characterized in that the caster angle adjustment mechanism is controlled to obtain a caster angle that reduces vibration.

[Function] In the vehicle caster angle control device of the present invention described above, when vibration occurs in the vehicle when the vehicle is stopped, the control means controls the caster angle adjustment mechanism to reduce vehicle vibration based on information from the vibration detection means. Control is performed so that the caster angle is small. Vibration of the vehicle is suppressed by this caster angle adjustment.

[Embodiment] Below, a caster angle control device for a vehicle as an embodiment of the present invention will be explained with reference to the drawings. Fig. 1 is a flowchart showing the details of the caster angle control, and Fig. 2 shows the caster angle adjustment mechanism. 3 is a perspective view showing the suspension equipped with the caster angle adjustment mechanism, FIG. 4 is a hydraulic circuit configuration diagram of the actuator,
FIG. 5.6 is a perspective view of the seat and a side view of the lower part of the seat, respectively, showing the location where the imaging sensor is installed.

First, to explain the suspension of the vehicle equipped with this device, the suspension of this embodiment is a strut-type front suspension for a passenger car, as shown in FIG. As is well known, the shock absorber 2 is constructed by combining a coil spring 3 with a shock absorber 2, and the head of each strut 1, 1 is fixed to the vehicle body 4 side. A front wheel 7 is rotatably attached to the lower end of each strut 1 via a knuckle 5 and a hub 6.

Further, 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 serve as a subframe, and constitutes a suspension using the shock absorber 2 as a part of the suspension link. ing.

Note that 10 is a center member provided on the cross member 9, and 11 is a disc brake.

And the head IA of these struts 1 and 1.

Attach these heads IA and IA to the mounting part of IA, respectively, on the vehicle body 4.
12. Caster angle adjustment mechanism (slide mechanism) that can freely adjust the caster angle by sliding it in the front and back direction.
12 are provided.

In addition, in FIG. 3, 27 is a drive shaft, and 28 is a stabilizer.

These caster angle adjustment mechanisms 12.12 are all constructed in the same way, and as shown in FIG.
and a slide plate 13 attached to the upper end of the strut 1 and capable of sliding with respect to a slide base 14.

The slide base 14 has a structure in which, for example, a substantially rectangular through hole 16 parallel to the longitudinal direction of the vehicle body is provided in the center of a plate member 15 whose longitudinal side faces the longitudinal direction of the vehicle body. A pair of rail portions 17.1 consisting of walls having a substantially triangular cross section on the entire two sides corresponding to the width direction side.
7 are installed in parallel. These rail parts 17.17 are all arranged inward, and the head IA of the strut 1 passes between these opposing rail parts 17.17 and inside the through hole 16. In addition, 1
7a is a rib for supporting the rail portion 17.

On the other hand, the slider plate 13 is provided with a substantially rectangular plate member 18 having dimensions corresponding to the distance between the rail parts 17 and 17 of the slide base 14, and the entire two parallel sides of this plate member 18 on the rail part side. It is provided with the above-mentioned rail portion 17.17 and wedge-shaped sliding wall portions 19, 19 which can be freely inserted.

The sliding wall portion 19.19 has a wedge-shaped cross section, for example, a symmetrical triangular wall with the sides of the plate member 18 as the apex.
It is installed integrally on the side of the.

The slide plate 13 is in sliding contact with the rail portion 17.17 without any wobbling.
7, it is guided by this rail portion 17.17 and can slide in a certain direction.

Note that between each sliding wall portion 19 and the opposing rail portion 17, a needle roller bearing 20, which is formed by, for example, a plurality of roller bearings arranged in parallel, is interposed along the sliding direction, and the slider plate 13 is moved between the front and back of the vehicle body. stable along the direction,
This allows for smooth sliding. In Figure 2,
Reference numeral 21 denotes a bearing transfer surface provided on the outer surface of each stroke of the sliding wall portion 19, and is composed of a rectangular recess.

The upper end of the strut 1 passes through the slide base 14 and is fitted into a circular opening 13a provided at the center of the slide plate 13. Further, a pair (two) of fixing holes 22.22 are provided in front and rear of the opening 13a, for example, in the insulator portion 1a of the head IA of the strut 1.
A mounting bolt 23.23 protrudes from the fixing hole 22.2.
By fastening these mounting bolts 23 and 23 to 2, the head IA of the strut 1 is integrated with the slider plate 13. This allows the caster of the front suspension to be varied by sliding the slider plate 13 in the longitudinal direction. Note that 24 indicates a nut for fastening the strut head.

An actuator (drive device) 25 for moving the strut head in the longitudinal direction of the vehicle body is directly connected to each slide plate 13 of the slide mechanism 12.12. This actuator 25 may be of a hydraulic type, for example, as shown in the figure, in which a hydraulic cylinder 2.5B is driven through a hydraulic supply/discharge system 25A having a hydraulic switching valve such as a solenoid valve.

In this case, for example, a hydraulic circuit configuration as shown in FIG. 4 may be considered. In FIG. 4, 25a is a tank in which hydraulic oil is stored, 25b is a pump, 25C is a pump accumulator, 25d and 25e are main accumulators, and 25f
is a filter, 25g is a relief valve, 25h is a check valve, 25i, 25j, 25, 251 is a control valve, and 25m, 25n are position sensors.

Other symbols are the same as above.

A controller (consisting of a microcomputer and its peripheral circuits) 26 as a control means is connected to the actuator 25, and the controller 26 receives signals from various sensors 29 (for example, a vehicle speed sensor and a vehicle vibration sensor). Based on the information, the angle of the caster can be changed according to the vehicle speed V and the intensity of vehicle vibration Igl.

The vibration sensor 29b is a sensor that detects the strength g of vibration of the vehicle, but here, as shown in FIG. A G sensor is provided, and is capable of detecting the strength of vibration in the vertical direction at the bottom of the seat. Further, the vibration sensor 29b detects the vibration of the vehicle as g with directionality, but since directionality is not required here, the intensity of vehicle vibration Igl is used as data for control.

Based on the detection information from the vibration sensor 29b, the controller 26 controls the caster angle so as to change the caster angle to reduce the vehicle body vibration when the intensity Igl of vehicle body vibration (seat bottom vibration) becomes larger than a threshold value. It is adapted to control the actuator 25 of the regulating mechanism 12.12. Note that here, the caster angle is changed by feedback control in response to increases and decreases in vehicle body vibration.

Since the vehicle caster angle control device as an embodiment of the present invention is constructed as described above, caster angle control is performed as shown in FIG.

That is, first, immediately after turning on the ignition switch of the car, etc., initialize the control parameters such as setting the flags Fl and F2 to 0 (step 51), and set the vehicle speed V and the intensity of heavy vehicle vibration Igl respectively. Read from the sensor 29 (step S2).

Then, in the following step S3, it is determined whether the vehicle speed V is approximately O, and if the vehicle speed V is not approximately O, the process returns to Step S2. Therefore, while the vehicle is running, the control steps of step S2→step S3→step S2 are repeated.

If it is determined in step S3 that the vehicle speed V is approximately O, the process proceeds to step S4, where it is determined whether the vehicle vibration intensity Igl is greater than a threshold value. Furthermore, I
I(IK is set according to the target vibration suppression level for each vehicle type.

If the vibration intensity Igl is smaller than the threshold value, it is assumed that the vehicle body vibration is sufficiently small, and the process proceeds to step s12, sets the flag F1 to 0, and returns to step s2.

If the strength of m motion Igl is larger than the threshold value, step S
Proceeding to step 5, it is determined whether the flag F1 is 1. This flag F1 is set to 1 when the first stage of vehicle body vibration suppression control is performed.

At the stage when the vehicle body vibration above a certain level starts to occur, the flag Fl is O, so the process proceeds to step s6, and a control signal is sent from the controller 26 to the actuator 25 to increase the caster.

The reason why this first stage control is caster increase control is as follows.
Generally, this is done because increasing the caster angle to improve vehicle stability leads to suppressing vehicle body vibration.

Then, in the following step s7, the flag Fl and the flag F2 are
are both set to 1. The flag F2 is set to 1 when the caster increase control is performed, and is set to 0 when the caster decrease control is performed.

This ends the current control cycle, and in the subsequent control cycle, step S2. Step 53゜Step S4
Proceeding to step S4, if it is determined that the vibration intensity Igl is greater than the threshold value, Fl is set to 1 this time, so the process advances from step S5 to step S8.

In this step S8, it is determined whether the intensity Igl of vehicle body vibration is increasing. This determination can be made by comparing the strength of the vehicle body vibration in the previous control cycle and the magnitude of the steering reaction force in the current control cycle.

If the strength of the vehicle body vibration has not increased, the process advances to step S9, but if the strength of the vehicle body vibration has increased, the process advances to step S9.
Proceed to step 13.

If the strength of the vehicle body vibration is decreasing and the process proceeds to step S9,
Determine whether flag F2 is 1. In this case, since the flag F2 was set to 1 in the previous control cycle, it means that the strength of the vehicle body vibration has decreased as a result of the previous caster increase control, so the process advances to step S10 to further increase the caster. Increase control is performed to further reduce the strength of vehicle body vibration.

Further, if the flag F2 is O, it means that the caster reduction control was performed in the previous control cycle, and the strength of the vehicle body vibration has been reduced, so the process advances from step S9 to step S14 to further reduce the caster. Control is performed to further reduce the intensity of vehicle body vibration.

On the other hand, if the strength of the vehicle body vibration is increasing, step 51
Proceeding to step 3, it is determined whether the flag F2 is 0 or not. If this flag F2 is not 0, it means that the strength of the vehicle body vibration has increased as a result of the caster increase control, so the process advances to step 814 and caster decrease control is performed in the opposite manner to the previous time.

Further, if the flag F2 is 0, it means that the strength of the vehicle body vibration has increased as a result of the caster reduction control, so the process advances from step 513 to step S10 and caster increase control is performed in the opposite manner to the previous time. .

Note that the control amount in the caster increase control in step S10 and the caster decrease control in step 514 is second-stage control, and is considerably smaller than the control amount in the first-stage caster increase control in step S6 described above. It is something.

After step S10, flag F2 is set to 1 in step S11, and after step 814, step S1 is set to 1.
At step 5, the flag F2 is set to O, and each control cycle ends.

In this way, the caster angle is increased (step 510) or decreased (step 51) in accordance with the increase or decrease in the strength of vehicle body vibration.
4) to converge the strength of the vehicle body vibration to within the threshold value.

As a result, vibrations occurring in the vehicle can be suppressed to within limits through automatic adjustment of the camber angle, and ride comfort for the driver and other passengers can be improved.

In particular, in this embodiment, the vibration sensor 29b is provided on the seat riser at the bottom of the seat 4o of the driver's seat, etc., so that feedback control is performed while directly detecting the imaging applied to the driver or other occupants. This makes it possible to appropriately suppress vibrations that are uncomfortable for the occupants.

Note that the detection direction of the vibration sensor 29b is set in the vertical direction, but this is because there are generally many vertical vibration components, which causes a problem when a car or the like stops.
The detection direction may be set to another direction, or vibrations in a plurality of directions may be detected and caster control for suppressing vibrations may be performed based on the detected information.

Further, the installation position of the vibration sensor 29b is not limited to that of this embodiment, and it is also possible to install it at a position such as a body part under the seat.

By the way, in the control flow shown in FIG. 1 described above, the control amount of the caster increase control in step S6 and the control amount in step S
Proceed to step 514 to make the control amount of the caster increase control in step 10 the same as the control amount of the caster decrease control, first increase the caster angle by a small amount, and then set to perform feedback control based on this result. Good too.

Further, depending on the characteristics of the vehicle, it is also possible to set the control in step S6 to caster reduction control. In this case as well, in addition to setting the control amount for this caster reduction control to a large value, it may also be set to a small value similar to step 510° S14.

Note that the application of this caster angle control device is not limited to the suspension configured as in this embodiment and the caster angle adjustment mechanism (slide mechanism) 12, but by driving the suspension elements, it can be adjusted appropriately as described above. It is widely applicable to other configurations as long as the caster angle can be controlled.

[Effects of the Invention] As detailed above, according to the vehicle caster angle control device of the present invention, the caster angle can be adjusted in the vehicle suspension by driving the components of the suspension. a caster angle adjustment mechanism that controls the caster angle, a control means for controlling the caster angle adjustment mechanism, and a vibration detection means for detecting vibrations of the vehicle, and the control means detects vibrations from the vibration detection means when the vehicle is stopped. The caster angle adjustment mechanism is configured to control the caster angle to take a caster angle that reduces vibrations of the vehicle based on the information, so that when the vibrations generated in the vehicle become large when the vehicle is stopped, the caster adjustment mechanism will surely adjust the caster angle. This has the advantage that the riding comfort of the vehicle can be greatly improved.

[Brief explanation of the drawing]

1 to 5 show a caster angle control device for a vehicle as an embodiment of the present invention, FIG. 1 is a flowchart showing the details of the caster angle control, and FIG. 2 shows the caster angle adjustment mechanism. Figure 3 is a perspective view showing the suspension equipped with the caster angle adjustment mechanism, Figure 4 is the hydraulic circuit diagram of the actuator, and Figures 5 and 6 are sheets showing the locations where the imaging sensors are installed. FIG. 2 is a perspective view and a side view of the lower part of the seat. 1- strut, IA- head of strut 1, la- insulator part, 2- shock absorber, 3- coil spring, 4- body, 5- knuckle, 6- hub, 7
-Front wheel, 8-Lower arm, 9-Cross member, 10-
Center member, 11-disc brake, 12-caster angle adjuster-1 (slide mechanism), 13-slide plate, 13a-opening, 14-slide base, 15-plate member, 16-through hole, 17-rail part, 17a-rail part,
18-Plate member, 19-Sliding wall portion, 20-Needle roller bearing, 22-Fixing hole, 23-Mounting bolt, 24-
Nut, 25-actuator (drive device), 25A-hydraulic supply and discharge system, 25B-hydraulic cylinder, 25a-tank, 2
5b-Pump. 25cm pump accumulator, 25d, 25e-main accumulator, 25f-filter, 25g-relief valve, 25h-check valve, 25i, 25j,
25, 251-control valve, 25m, 25n
-Position sensor, 26-Controller, 27-Drive shaft, 28-Stabilizer 29-Various sensors (
For example, vehicle speed sensor or vibration sensor), 29a-vibration sensor. 40-sheets. 41-Seat riser.

Claims (1)

[Claims] A suspension for a vehicle that includes a caster angle adjustment mechanism that can adjust a caster angle by driving components of the suspension, a control means that controls the caster angle adjustment mechanism, and a vibration that detects vibrations of the vehicle. A detection means is provided, and the control means is configured to control the caster angle adjustment mechanism to take a caster angle that reduces vibration of the vehicle based on information from the vibration detection means when the vehicle is stopped. A caster angle control device for a vehicle, characterized in that: