JPH04215511A - Suspension control system - Google Patents

Abstract

PURPOSE:To regulate a damping force to the desired or optimum one corresponding to a road condition and personal liking in a vehicle having suspension systems interposed respectively in the chassis side and carbureter side by ensuring controllability in basic high speed travelling and good riding quality in low and intermediate speed regions. CONSTITUTION:A means for changing over a damping force uniformly in the chassis side suspension system on the basis of travelling speed of an automobile while changing over the damping force following the chassis side damping force in the carbureter side suspension system and a means for maintaining constant the damping force of the carbureter side suspension system irrespective of that of the chassis side suspension system are prepared characteristically to be selected by a manual change-over means.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a suspension control system for trucks, etc., in which a shock absorber or other suspension capable of variable damping force is interposed on each of the chassis side and the driver's cab (hereinafter referred to as the cab). The present invention relates to a suspension control method that improves steering stability when the vehicle is running at high speed.

0002

[Prior Art] In general, the suspension stiffness of vehicles, including passenger cars, is set to be soft in order to improve ride comfort during steady driving.However, when driving at high speed in such conditions, it becomes difficult to control There is a problem that stability is greatly reduced.

For this reason, conventional methods have been to detect the vehicle speed while the vehicle is running, and to vary the damping force of the shock absorber that constitutes the suspension as appropriate based on the detected signal. At low to medium speeds, the suspension is set to soft,
On the other hand, when the vehicle speed increases to 70 to 80 km/h or more, this is detected by a vehicle speed sensor, etc., and the suspension is switched to a harder one to improve steering stability and safety. is proposed.

On the other hand, unlike passenger cars, for example, in cab-over type trucks, in order to ensure a stable ride during long-distance driving, there is a There are vehicles with suspension.

[0005]

[Problem to be solved by the invention] In such a vehicle, controlling the damping force of each individual suspension in accordance with the vehicle speed not only makes the control operation extremely complicated even if it is automated, but even if automation is possible, it is difficult to control the damping force of each suspension in accordance with the vehicle speed. However, it has been difficult to accurately satisfy the conflicting demands of handling stability and ride comfort.

In view of the shortcomings of the prior art, the present invention aims to improve basic handling stability during high-speed running and ride comfort in the low-to-medium speed range in a vehicle that has suspensions on both the chassis side and the cab side. It is an object of the present invention to provide a suspension control system that can adjust the damping force to a desired or optimal damping force in response to road conditions and personal preferences while ensuring the same damping force.

[0007]

[Means for Solving the Problems] The present invention is designed to reduce the damping force of the chassis side suspension, which has the greatest influence on handling stability, at the point when the vehicle speed is switched from a low-medium speed range to a high speed range (for example, at 80 km) based on a vehicle speed detection signal. The first feature is that the speed is uniformly changed from soft to hard when the speed range is 70 km/h), and from hard to soft when the speed range is changed from a high speed range to a low-medium speed range (for example, 70 km/h).

On the other hand, regarding the suspension on the cab side,
As a general rule, steering stability is prioritized, and the damping force of the cab side suspension is configured to be switchable to follow the damping force of the chassis, but in case of road conditions or high speed driving close to the medium speed range, the cab side suspension is not always available. There is no need to set it to hard; for example, in consideration of ride comfort, it may be better to set it to a hardness (normal) between hard and soft. Also, even when driving at low to medium speeds, depending on personal preference, it may be better to set the suspension to the normal setting without having to follow the chassis suspension and make it soft.

Therefore, the second feature of the present invention is that the damping force of the cab side suspension is maintained constant regardless of the damping force of the chassis side suspension, without making the cab side suspension uniformly follow the chassis side. The present invention is constructed so that the selection is performed by a manual switching means.

0010

[Operation] According to this technical means, the deceleration of the suspension on the chassis side can be switched in accordance with the traveling speed, and on the other hand, the suspension on the cab side can also be switched in principle to follow the deceleration on the chassis side. Therefore, automation can be easily performed without complicating the device configuration.

[0011] Furthermore, although the above configuration can ensure basic steering stability at high speeds and ride comfort at low and medium speeds, since the control is uniform, it cannot be adjusted to suit road conditions or individual preferences. Therefore, the damping force cannot be adjusted to the desired or optimum damping force.

[0012] Since the configuration would be complicated if such variation control were to be performed automatically, the present invention is configured such that the control is performed by a manual switching means, and is independent of the damping force of the chassis side suspension. By maintaining the damping force of the cab-side suspension at a constant level, or more specifically by setting it to a stiffness between hard and soft (normal), in other words, it is possible to shift to the variation control simply by operating switch 1. Since this is possible, the above object can be smoothly achieved with simple operations and without any operational errors.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail by way of example with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, and relative positions of the components described in this example are not intended to limit the scope of this invention, but are merely illustrative examples. Not too much.

FIG. 2 shows a schematic configuration of a cab-over type truck according to an embodiment of the present invention, in which a pair of left and right cab suspensions 3 are provided between the cab 1 and the chassis 2, on the front end side and the rear end side of the cab 1, respectively. A pair of left and right chassis suspensions 4 are provided on the front wheel side and the rear wheel side between the axle and the chassis 2, respectively.
are arranged respectively.

As is well known, the suspensions 3 and 4 include shock absorbers 3A and 4A whose damping force can be varied in stages by voltage control to an internal actuator, as well as coil springs or roof springs (not shown). They are installed consecutively. That is, more specifically, the shock absorber 4A on the chassis 2 side has a damping degree that can be switched in two stages, large/small, and thereby the chassis suspension 4 can be set in two stages, hard and soft (hard/soft). . On the other hand, the shock absorber 3A on the cab 1 side has a damping degree that can be switched in three stages: large, small, and medium.This allows the cab suspension 3 to be set in three stages: hard, soft, and in between (hard/soft/normal). do.

Further, electrical components such as various sensors for performing suspension control, which will be described later, are attached to the inside of the cab 1 or the chassis 2. Cab 1 for electrical equipment
To explain in order of the inside and the chassis 2 side, 11 is an ECS mode changeover switch for manual control, and consists of a hard switch 11a and a soft switch 11b for setting the damping degree of the shock absorber 4A on the chassis 2 side to be large or small.

Reference numeral 12 is a changeover switch on the cab suspension 3 side, which selects between an auto mode in which the damping degree is set to hard and soft based on the control signal from the control side, and a normal damping degree regardless of the damping degree on the chassis 2 side. It is configured to be switchable between a normal mode and a normal mode. 13 is a brake switch, which is turned on by stepping on the foot brake. Reference numeral 20 denotes a control unit in which various ICs for performing control operations described later are incorporated.

A pair of acceleration sensors 14 are installed near the left and right front wheels, and detect vertical movements of the vehicle such as pitching and bouncing. (hereinafter referred to as vertical G sensor)
A vehicle speed sensor 15 is attached to the output shaft of the transmission 16 and detects the traveling speed of the vehicle.

FIG. 3 is a control block diagram showing the overall configuration of the suspension control mechanism built into the vehicle, including a control unit 20 in which a manual control circuit 20A and an automatic control circuit 20B are built, the chassis 2 side and the cab. Control circuits 21 and 2 that switch the damping level of the actuators incorporated in the shock absorbers 3A and 4A on the 1 side, respectively.
Consists of 2.

The auto control circuit 20B in the control unit 20 includes a pitching/bouncing control circuit 20B1, an unsprung (suspension spring on the chassis side) flapping control circuit 20B2 when going over a step/protrusion, a high-speed driving control circuit 20B3, and a nose control circuit 20B2. It has a dive control circuit 20B4, and together with the manual control circuit 20A, it sends either hardware or software control signals to the control circuits 21 and 22 on the chassis 2 side and the cab 1 side, respectively, based on the above-mentioned sensor signals.
The configuration is such that the output is output to the system and predetermined control is performed.

The control circuit 22 on the cab 1 side includes an auto/normal selector switch 12, a power relay 23, and a power supply unit that outputs a voltage corresponding to the attenuation level (hard/soft/normal) to the actuator in the shock absorber. 24, etc., and the changeover switch 12
When is in auto mode, generally a control signal corresponding to the attenuation level on the chassis 2 side is sent to the control unit 20.
is output to the power supply unit 24 via the power relay 23, thereby supplying the voltage corresponding to hardware/software to the actuator 25. On the other hand, when the changeover switch 12 is switched to normal mode, the control unit 20 side By outputting an ON signal from the changeover switch to the power supply unit 24 via the power relay 23, a constant voltage corresponding to the normal mode can be supplied to the actuator 25, regardless of the control signal.

In the figure, reference numeral 1 indicates an operation indicator light indicating the attenuation level (hard/soft/normal) of the shock absorber, and reference numeral 19 indicates a failure diagnosis light for various sensors.

Next, the present control method will be explained step by step based on the flowchart shown in FIG. 1 and the time chart shown in FIG. First, after starting operation, the manual control circuit 20A in the control unit 20 first determines whether or not the hard switch 11a is turned on, based on the signal from the mode changeover switch 11, and if it is turned on, the manual It is determined that it is a hard setting for operation, and the damping degree of the shock absorber 3A (actuator) on the chassis 2 side and the cab 1 side is set to the hard side.

Next, when the hard switch 11a is OFF and the soft switch 11b is ON, it is determined that the soft setting is for manual operation, and the damping degree of the shock absorber 3A on the chassis 2 side and the cab 1 side is set to the soft side. Set. Since these manual controls are not essential parts of the present invention, detailed explanation thereof will be omitted. (STEP 1)

002
5] If both the hard switch 11a and the soft switch 11b are OFF, the system shifts to auto mode control (STEP 2), and if the high-speed running control flag is not set (STEP 3), the signal from the vehicle speed sensor is activated. Based on this, it is determined whether the vehicle speed is 80 km/h or more, and if the vehicle speed is 80 km/h or higher, it is determined that the vehicle is traveling at a high speed, and a high speed travel control flag is set. (STEP 4) Next, cab 1
The switch 12 on the side determines whether it is auto or normal, and if it is auto, the switch 12 on the chassis 2 side and the cab 1
The damping degree of the side shock absorber 3A (actuator) is set to the hard side (STEP 5), and if it is normal, only the chassis 2 side is set to hard, and the cab 1 side is set to normal. (STEP 6)

If the vehicle speed is less than 80 km/h, it is determined that the vehicle is still running at a low-medium speed (STEP 7), and then, similarly to the above, it is determined whether the changeover switch 12 on the cab 1 side is set to auto or normal. However, in the case of auto, set the damping degree of the shock absorber 3A on the cab 1 side as well as the chassis 2 side to the soft side (ST
EP8), and if it is normal, set only the chassis 2 side to soft and the cab 1 side to normal. (STEP 9)

On the other hand, if the high-speed running control flag is set, it is determined that the high-speed running state is in progress (STEP 10).
), the vehicle speed is 70 km/h based on the signal from the vehicle speed sensor.
When the speed drops below h, it is determined that the vehicle has shifted to low-medium speed travel, and the high-speed travel control flag is cleared. (STEP 11
), similarly to the above, the changeover switch 12 on the cab 1 side determines whether it is auto or normal, and if it is auto, the shock absorber 3A on the cab 1 side as well as the chassis 2 side
Set the damping degree to the soft side (STEP 8), and if it is normal, set only the chassis 2 side to soft and the cab 1 side to normal. (STEP 9) Also, the vehicle speed is 70k
m/h or more, it is determined that you are still driving at high speed (S
Repeat steps 5 and 6).

If, for example, pitching/bouncing occurs during the traveling, the control circuit 20B1 determines this based on the signal from the vertical G sensor 14, giving priority to the control described above, and controls the control circuit 20B1 based on the output control signal. Both the chassis 2 side and the cab 1 side are set to hard, and similarly, if a bump/protrusion occurs, the control circuit 20B2 side determines this based on the signal from the G sensor 14 and controls the output. Based on the signal, the chassis 2 side was set to hard and the cab 1 side were both set to soft, and when the brake switch was turned on again, the deceleration corresponding to the change in vehicle speed per unit time became below a certain level. In this case, the control circuit 20B4 side judges this and sets both the chassis 2 side and the cab 1 side to hard based on the output control signal.

[0029]

As described above, according to the present invention, even when suspensions are provided on both the chassis side and the cab side, such as in a cab-over type truck, basic handling stability at high speeds and low to medium speeds can be improved. It is possible to adjust the deceleration of both suspensions with a single manual operation by adjusting the desired or optimal damping force in response to road conditions and individual preferences, while ensuring a comfortable ride in the range of driving conditions. You can set the desired damping force with a simple switch or lever operation without having to
This further improves marketability and usage value. It has various effects such as

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing the high-speed driving control state of suspension control, which is the main component of the present invention.

FIG. 2 is an overall diagram showing a schematic configuration of various parts incorporated in a cab-over type truck according to an embodiment of the present invention.

FIG. 3 is a control block diagram showing the overall configuration of the suspension control mechanism built into the vehicle.

[Figure 4] Time chart diagram of the high-speed control state shown in Figure 1

[Explanation of symbols]

1 Cab 2 Chassis 3, 4 Suspension 20 Control unit

Claims (1)

[Claims] Claim 1: In a suspension control system for a vehicle in which a suspension with variable damping force is interposed on each of the chassis side and the cab side, the damping force of the chassis side suspension is uniformly switched based on the vehicle traveling speed, On the other hand, for the cab side suspension, means for switching the damping force to follow the damping force on the chassis side;
A suspension control system characterized in that means for maintaining the damping force of the cab side suspension constant regardless of the damping force of the chassis side suspension is provided, and the selection thereof is made by a manual switching means.