JPH04215513A - Suspension control - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a suspension control method for a truck or the like in which a shock absorber or other suspension capable of varying 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 capable of smoothly absorbing vibrations generated when riding over road irregularities such as steps and protrusions without sacrificing riding comfort or steering stability.

0002

[Prior Art] Conventionally, in order to improve steering stability and ride comfort depending on vehicle speed or road conditions while driving, it has been possible to vary the damping force of shock absorbers that make up the suspension in stages. Suspension control devices that are configured such that the damping force can be appropriately switched are known. (Special Public Interest Publication No. 63-63401)

[0003] In this type of device, the driving condition, the presence or absence of braking force, and the road condition are ascertained based on various signals from a G sensor that detects vehicle speed, deceleration, or vertical vibration of the vehicle, and the above-mentioned information is automatically detected. Although the damping force is configured to be variable, the vibrations generated when driving over bumps, bumps, and other road irregularities occur for a short period of time, and it is difficult to distinguish them from the vertical movement caused by pitching or bouncing. It is quite difficult. For this reason, in conventional vehicles, the damping force of the suspension is set to be hard when the acceleration level from the G sensor exceeds a certain level without distinguishing between the two.

[Problem to be solved by the invention]

However, if the suspension mechanism is only on the chassis side (between the tires and the chassis) like a passenger car, there is little risk of this problem occurring, but if the suspension mechanism is only on the chassis side like a cab-over type truck. In vehicles that have a suspension on the cab side (between the chassis and the cab), pitching and bouncing have a long period of vertical motion and have a normally distributed waveform, and pitching and bouncing have a short period of vertical motion and have a waveform with an acute angle. Uniform control of step/protrusion vibrations having a typical peak waveform not only sacrifices steering stability and ride comfort, but also may not be able to effectively suppress the vibrations themselves. In addition, since pitching and bouncing must be detected at a lower acceleration than vibrations of steps/protrusions, there is a drawback that noise is easily picked up.

In view of the drawbacks of the prior art, the present invention provides a method for accurately and reliably detecting vehicle vibrations such as pitching and bouncing, and effectively suppressing the vibrations without sacrificing steering stability and ride comfort. It is an object of the present invention to provide a suspension control method that can suppress the suspension.

[0006]

[Means for Solving the Problems] The first feature of the present invention is that suspension control for suppressing bump/protrusion vibration is not performed when the vehicle speed is below a certain speed. Even if a bump/protrusion vibration occurs in the low-speed range, it does not generate enough acceleration to affect ride comfort, and on the other hand, controlling the suspension at this level of acceleration will only complicate the configuration and reduce steering stability. However, because the acceleration is small, it is not possible to accurately detect step/protrusion vibrations.

[0007] Therefore, the second feature is that the control or detection operation for suppressing bump/protrusion vibration is performed only when the vehicle speed rises above a certain speed, specifically above 20 km/h. be.

The third feature is that the amplitude of the detection output of vehicle vertical vibration is within a long wave cycle range corresponding to vehicle rocking such as pitching or bouncing, and there are two or more consecutive half wave cycles of a predetermined acceleration or more. More specifically, when the half-wave period (1/2 frequency) of the detected output waveform is approximately 2 to
When there are two or more consecutive half-wave cycles within 5 Hz (approximately 0.1 to 0.25 sec) and whose acceleration is, for example, 0.1 g or more, the control described later is performed while the half-wave cycle with the acceleration or more continues. It lies in the point of performing an action.

That is, if the half-wave period is only one, there may be a noise error, but since two or more half-wave periods are picked up, pitching and bouncing fluctuations can be picked up reliably and with high precision.

In this case, the frequency range of 2 to 5 Hz increases slightly if the frequency measurement starting point is set at 0.005 G as in the embodiment described later. Therefore, the range is not approximately 2 to 5 Hz in a strict sense, but also includes approximately 1 to 7 Hz.

[0011] The reason for limiting the frequency to approximately 2 to 5 Hz is that the resonance point of the chassis side suspension (unsprung), which is most susceptible to bump/protrusion vibrations, is around 10 Hz, and the resonance point of the cab side suspension (sprung) is around 10 Hz. is around 2Hz, and therefore, setting the frequency within the above range can directly suppress the resonance on the spring, which leads to effective pitching and bouncing suppression, which is not only desirable, but also reduces vibrations that are likely to cause car sickness. This depends on matching the range. This is the fourth feature.

[0012] The reason for setting the lower and upper limits of the output waveform is that if vertical movements with a half-wave period of approximately 2 Hz or less are picked up, even vibrations generated due to variations in running conditions will be controlled. do not have. In addition, vibration components of approximately 5 Hz or higher pick up even extremely short wavelength vibrations caused by step/protrusion vibrations, making it impossible to distinguish and control these. A fourth feature of the present invention is that the damping force of both the chassis side suspension and the cab side suspension is switched to the hard side for a predetermined period of time.

[0013] As a result, since the chassis side is also hard-switched, pitching and bouncing oscillations can be suppressed without sacrificing ride comfort or handling stability. According to the second aspect of the invention, the damping force of the chassis side suspension, which has the greatest influence on pitching and bouncing suppression, is always switched to hard for a predetermined period of time, but the damping force on the cab side is allowed to have some tolerance. In the case of rough road conditions or high-speed driving, it is not necessarily necessary to set the cab side suspension to hard as described in claim 1. ) may be better.

That is, the invention according to claim 2 includes means for setting the damping force of the cab-side suspension to a hard level based on the control signal generated during the pitching or bouncing;
The present invention is characterized in that a means for maintaining the damping force of the cab side suspension at a constant level (normal or hard) irrespective of the control signal is provided, and the selection thereof is performed by a manual switching means.

[0015]

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 designates 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 running speed of the vehicle.

FIG. 3 is a control block diagram showing the overall configuration of the suspension control mechanism built into the vehicle, which includes 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 20B1. 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 18 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, regarding the present pitching and bouncing control method, the flowcharts shown in FIGS. 4A and 4B and FIG.
A step-by-step explanation will be given based on the time chart shown in FIG. First, as shown in Figure 4A, after the start of driving, the vehicle speed is 20 km/h.
If it is less than h, the G sensor signal cycle detection timer and the half cycle condition satisfaction counter are cleared and the process returns to the original state. (STE
P1)

[0026] When the vehicle speed becomes 20 km/h or higher, if the peak detection flag, peakless flag, and G sensor signal detection start flag are not turned on (STEP 2), the wave height level of the G sensor signal is When Gn (corresponding to acceleration level) is Gn≧±0.005G, G
The sensor signal detection start flag is set, and at the same time, the same timer flag as the G sensor signal cycle detection timer is set, and the process returns to the original state. (STEP 3) In the following cases, the G sensor signal cycle detection timer and the half cycle condition satisfaction counter are respectively cleared and the process returns to the original state. (STEP 4)

Next, after the G sensor signal period detection timer flag is set, the current detected wave height level Gn is smaller in absolute value than the previous detected wave height level Gn-1 |Gn-1|>|Gn
| (STEP 5) Previously detected wave height level G
It is determined whether n-1 has exceeded the reference acceleration level ±0.1g, and if it has exceeded, a peak detection flag is set, and if it has not exceeded, a peakless flag is set. (STEP 6)

[0028] When the peak detection flag is turned on,
To check the half-wave period, repeat STEP 6 until Gn reaches ±0.005G, and if Gn≧±0.005
When it becomes G, clear the peak detection flag, check the G sensor signal period detection timer, and check if the timer is 0.01.
If ≦t≦0.25, the G sensor signal period detection timer is cleared and the half period condition satisfaction counter is incremented by 1 (STEP 7), and then the process returns to the original state. Then, as will be described later, when the counter reaches 2 or more, a transition is made to a pitching or bouncing control operation.

On the other hand, whether the timer is 0.1 sec or less or 0.
If it is 25 seconds or more, clear the G sensor signal cycle detection timer and half cycle condition fulfillment counter and return to the original state (
STEP 8). As described later, since the counter is cleared, the pitching and bouncing control operations are cleared.

In other words, when the peakless flag is set, Gn is ±0.0 until the half-wave period ends.
Step 9 is repeated until reaching 05G, and after completion, the peakless flag is cleared (STEP 10) and the above operations are repeated.

FIG. 4B shows the operation procedure of suspension control in pitching and bouncing. First, if the half-cycle condition satisfaction counter is less than 2 or cleared, it is determined that the driving state is normal (STEP 11), and the cab 1
If the changeover switch 12 on the side is set to auto, set the damping degree of the shock absorber 3A (actuator) on the cab 1 side as well as the chassis 2 side to the soft side (STEP 12).
, and in the case of normal, only the chassis 2 side is set to hard, and the cab 1 side is set to normal. (STEP 13)

00
32] On the other hand, if the half-cycle condition fulfillment counter is 2 or more, if the switch 12 on the cab 1 side is set to auto, the damping degree of the shock absorber 3A on the cab 1 side as well as the chassis 2 side is set to the hard side. (STEP 14)
, and in the case of normal, only the chassis 2 side is set to hard, and the cab 1 side is set to normal. (STEP 15) After the pitching and bouncing are completed, the half-cycle condition fulfillment counter is cleared, a normal running state is entered, and the process returns to STEP 11. The above operation is then repeated.

To briefly explain the overall suspension control operation of this embodiment, this embodiment is divided into manual mode control operation and auto mode control operation. Control circuit 2
At 0A, it is first determined whether or not the hard switch 11a is turned on. If it is turned on, it is determined that the hard setting is for manual operation, and the shock absorber 3A (actuator) on the chassis 2 side and the cab 1 side is damped. Set the degree to hard side.

Next, if 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. If both the hard switch 11a and the soft switch 11b are OFF, the control shifts to automatic mode control.

In the auto mode control, as described above, the suspension on the chassis side and the cab side are respectively set to soft settings, and if, for example, pitching/bouncing occurs during the driving, priority is given to the above control. This is judged on the control circuit 20B1 side based on the signal of the vertical G sensor 14, and based on the output control signal, both the chassis 2 side and the cab 1 side are set to hard, and similarly, the control circuit 20B1 side makes it hard to drive over steps/protrusions. If this occurs, as described above, the control circuit 20B2 side determines this based on the signal from the G sensor 14, and based on the output control signal, both the chassis 2 side is set to hard and the cab 1 side is set to soft. Furthermore, when the vehicle speed sensor shifts to a high-speed driving state, the control circuit 20B4 side determines this and controls the chassis 2 based on the output control signal.
Both side and cab 1 side are set to hard, and furthermore, when the brake switch is turned on and the deceleration corresponding to the change in vehicle speed per unit time becomes below a certain level, this is set on the control circuit 20B4 side. is determined to be a nose dive, and both the chassis 2 side and the cab 1 side are set to hard based on the output control signal.

[0036]

[Effects of the Invention] As described above, according to the present invention, even in a vehicle in which suspension is provided on both the chassis side and the cab side, pitching can be prevented accurately and reliably while ensuring ride comfort during driving. Bouncing can be prevented.

Further, according to the present invention, it is possible to perform desired or optimal suspension control in response to road conditions, driving conditions, or personal preferences while suppressing pitching and bouncing, and the above operations can be performed by manual switching operations. Since it is possible to do this, the product quality and use value are further increased without complicating the configuration. It has various effects such as

[Brief explanation of the drawing]

[Figure 1] Time chart diagram of pitching and bouncing control shown in Figure 4

FIG. 2 is an overall configuration 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 4A] Flowchart diagram showing signal generation operation for pitching and bouncing control

FIG. 4B is a flowchart showing the operation procedure of pitching and bouncing control based on the signal.

[Explanation of symbols]

1 Cab 2 Chassis 3, 4 Suspension 20 Control unit

Claims (2)

[Claims] Claim 1: In a suspension control method for a vehicle in which a suspension with variable damping force is interposed on each of the chassis side and the cab side, the amplitude of the detected output of vehicle vertical vibration is on the cab side under conditions of a constant vehicle speed or higher. When at least two or more consecutive half-wave cycles with a predetermined acceleration or more occur within a long-wave cycle range that approximately corresponds to the resonance cycle of the suspension, the damping force of the suspension on the cab side and the chassis side continues to be affected by the half-wave cycle. A suspension control method characterized by switching to a hard side while 2. Means for setting the damping force of the cab side suspension to hard following the switching operation of the hard side suspension to the hard side, and maintaining the damping force of the cab side suspension constant regardless of the control signal. 2. The suspension control method according to claim 1, further comprising: a means for selecting the selected one, and a manual switching means for selecting the selected one.