JP2850538B2 - Suspension control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension control method for a truck or the like in which a shock absorber or another suspension capable of varying damping force is interposed on each of a chassis side and a cab (hereinafter referred to as "cab") side. The present invention relates to a suspension control method capable of smoothly absorbing vibration generated when a road uneven portion such as a step or a protrusion crosses over a road without sacrificing ride comfort and steering stability.

[0002]

2. Description of the Related Art Conventionally, in order to improve steering stability and ride comfort corresponding to vehicle speed or road conditions while driving a vehicle, the damping force of a shock absorber constituting a suspension can be changed stepwise. A suspension control device which is configured and capable of appropriately switching the damping force is known. (Special Publication 63-63401)

In this type of apparatus, the running state, the presence or absence of braking force, or the road state is grasped based on various signals from a G sensor or the like for detecting the vehicle speed, deceleration, or vertical vibration of the vehicle. Although the damping force is configured to be variable, the generation of vibration generated when jumping over road unevenness such as steps, projections, etc. is short-term, and it is difficult to distinguish from vertical movement in pitching and bouncing. It is difficult. For this reason, in the conventional vehicle, the damping force of the suspension is set to be hard (hard) when the acceleration level from the G sensor becomes equal to or higher than a certain level without distinguishing the two.

[0004]

However, in a device such as a passenger car in which a suspension mechanism exists only on the chassis side (between a tire and a chassis), there is little possibility that a problem occurs, but a device such as a cab-over type truck is used. To the cab as well as the chassis (between chassis and cab)
In the case of a vehicle with a suspension, pitching and bouncing have a long vertical movement cycle and a normal distribution waveform, and a step / projection having a short cycle and a sharp peak waveform. In the case of vibration, uniformly controlling the vibration not only sacrifices steering stability and ride comfort, but also may not effectively suppress the vibration itself. Further, in the case of pitching or bouncing, since it is necessary to detect at a lower acceleration than that of the step / projection vibration, there is a disadvantage that noise is easily picked up.

In view of the above-mentioned drawbacks of the prior art, the present invention accurately and reliably detects the vehicle swing such as pitching and bouncing without sacrificing steering stability and ride comfort, and effectively detects the vibration. It is an object of the present invention to provide a suspension control method that can be suppressed.

[0006]

A first feature of the present invention resides in that suspension control for suppressing step / projection vibration is not performed when the vehicle speed is equal to or lower than a predetermined speed. Even if a bump / projection vibration occurs in the low-speed range, acceleration that does not affect the ride comfort is generated. Conversely, performing suspension control with this level of acceleration only complicates the configuration and lowers steering stability. In addition, since the acceleration is small, the step / projection vibration cannot be accurately grasped.

[0007] Therefore, the car speed is constant vehicle speed or more, specifically intends row control or detection operation for suppressing the step / protrusion vibrations begin when rises above 20 km / h.

[0008] and where the second feature, the vehicle up and down direction
Where the amplitude of the detection output of the direction acceleration corresponding to vehicle oscillation of such pitching and bouncing, within the long wave period range corresponding substantially to the resonance period of the cab side suspension
It is equal to or greater than a predetermined value and has an amplitude equal to or greater than the predetermined value.
When at least two or more half-waves are continuous, that is, more specifically, the half-wave period (１ ／ frequency) of the detection output waveform is within about 2 to 5 Hz (about 0.1 to 0.25 sec) and The point is that when two or more half-wave periods of the acceleration of, for example, 0.1 g or more continue, the control operation is performed while the half-wave period of the acceleration or more continues.

That is, although there is a case where a noise error occurs when the half-wave period is only 1, fluctuations in pitching and bouncing can be reliably and accurately detected because two or more half-wave periods are picked up.

In this case, the frequency range from 2 to 5 Hz slightly increases when the starting point of frequency measurement is set to 0.05 g as in the embodiment described later. Therefore, the above-mentioned range includes not only about 2 to 5 Hz in a strict sense but also about 1 to 7 Hz.

The reason why the period is limited to about 2 to 5 Hz is that the resonance point of the chassis side suspension (unsprung) which is most susceptible to the step / projection vibration is around 10 Hz, and the cab side suspension (spring up). Is about 2 Hz, so setting the above-mentioned period range can directly suppress resonance on the spring, which leads to effective pitching and bouncing suppression, which is not only preferable, but also causes vibration sickness that tends to cause motion sickness. Depends on matching the range.

The reason for setting the lower limit and the upper limit of the output waveform is that, if the half-wave period is picked up to a vertical movement of about 2 Hz or less, the vibration generated due to the variation in the running state is controlled, so that it is preferable. Absent. In addition, a vibration component of about 5 Hz or more is picked up to an extremely short-wavelength vibration caused by the step / projection vibration, and cannot be controlled separately.

A third feature of the present invention resides in that the damping force of both the suspension on the chassis side and the suspension on the cab side is switched to the hard side for a predetermined time. As a result, the chassis is also switched to the hard side, so that the pitching and bouncing swing can be suppressed without sacrificing the riding comfort or the steering stability.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention; However, unless otherwise specified, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention, but are merely illustrative examples. Not just.

FIG. 2 shows a schematic configuration of a cab-over type truck according to an embodiment of the present invention. A pair of left and right cab suspensions 3 are provided between a cab 1 and a chassis 2 at a front end side and a 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.
Each is arranged.

The suspensions 3 and 4 include, as is well known, a coil spring or a roof spring (not shown) and shock absorbers 3A and 4A which are configured so that the damping force can be varied stepwise by controlling the voltage applied to the built-in actuator. It is installed continuously. That is, more specifically, the shock absorber 4A on the chassis 2 side switches the damping force between two levels of large / small, whereby the chassis suspension 4 can be set in two steps of hard and soft (hard / soft). . On the other hand, the shock absorber 3A on the side of the cab 1 switches the damping force between three stages of large / small / medium, thereby enabling the cab suspension 3 to be set in three stages of hard and soft and intermediate (hard / soft / normal). I do.

Further, electrical components such as various sensors for performing suspension control described later are attached to the inside of the cab 1 or the chassis 2. Cab 1
In the order of the inside and the chassis 2 side, reference numeral 11 denotes an ECS mode changeover switch for manual control, which comprises a hard switch 11a and a soft switch 11b for setting the damping force of the shock absorber 4A on the chassis 2 to a large or small value.

[0018] 12 is a change-over switch of the cab suspension 3 side, the automatic mode that damping force is set to hard and soft on the basis of the control signal of the control side, the damping force and independently of the damping force of the chassis 2 side to the normal It is configured to be able to switch to the normal mode for maintaining. A brake switch 13 is turned on by depressing a foot brake. Reference numeral 20 denotes a control unit in which various ICs for performing a control operation described later are incorporated.

Reference numeral 14 denotes a pair of acceleration sensors mounted near the left and right front wheels to detect vertical movement of the vehicle such as pitching and bouncing. (Hereinafter referred to as vertical G sensor)
Reference numeral 15 denotes a vehicle speed sensor attached to the output shaft of the transmission 16, and detects a running speed of the vehicle.

FIG. 3 is a control block diagram showing the overall configuration of a suspension control mechanism incorporated in the vehicle. The control unit 20 includes a manual control circuit 20A and an automatic control circuit 20B, a chassis 2 and a cab. A control circuit 21 for switching a damping force level of an actuator incorporated in each of the shock absorbers 3A and 4A on the first side;
22.

The automatic control circuit 20B in the control unit 20 includes a pitching / bouncing control circuit 20B1, an unsprung (chassis-side suspension spring) flapping control circuit 20B2 when stepping over a step / projection, a high-speed running control circuit 20B3, and a nose. It has a dive control circuit 20B4 and, together with the manual control circuit 20A, sends control signals, either hard or soft, based on the sensor signals described above to the control circuits 21, 22 on the chassis 2 side and the cab 1 side, respectively.
And performs predetermined control.

A control circuit 22 on the cab 1 side includes a power supply unit for outputting a voltage corresponding to a damping force level (hard / soft / normal) to an actuator in the auto / normal switch 12, a power relay 23, and a shock absorber. 24 and the like.
Is in the auto mode, the control signal generally corresponding to the attenuation level on the chassis 2 side is transmitted to the control unit 20.
The voltage is output to the power supply unit 24 via the power relay 23, thereby supplying a voltage corresponding to hardware / software to the actuator 25. On the other hand, when the changeover switch 12 is switched to the normal mode, the control unit 20 side Irrespective of the control signal, the ON signal from the changeover switch is output to the power supply unit 24 via the power relay 23, whereby the actuator 25 can be supplied with a constant voltage corresponding to the normal mode.

In the drawing, reference numeral 18 denotes an operation indicator lamp indicating the damping level (hard / soft / normal) of the shock absorber, and 19 denotes a failure diagnostic lamp for various sensors.

Next, the pitching and bouncing control method will be described with reference to the flow charts shown in FIGS. 4A and 4B and FIG.
Will be described in order based on the time chart shown in FIG. First, as shown in FIG. 4A, the vehicle speed is 20 km after the start of driving.
/ If h not on than is, G sensor signal period detection timer and half-cycle condition satisfaction counter respectively cleared (STEP1)
And go back.

If the peak speed flag, the peakless flag, and the G sensor signal detection start flag are not turned on when the vehicle speed exceeds 20 km / h (STEP 2), the peak level of the G sensor signal + Side detection when Gn (corresponding to acceleration level) is 0.05g or more
The flag is set, the G sensor signal detection start flag is set, and at the same time, the G sensor signal cycle detection timer and the timer flag are set, and the process returns to the original state (STEP 3).

Also, Gn is smaller than 0.05 g, and
Set the-side detection flag when -0.05g or less
And sets the G sensor signal detection start flag,
Set the sensor signal period detection timer and the same timer flag
Then, the process returns to the original state (STEP 3). Gn from -0.05g
If it is large (STEP 4) , the G sensor signal cycle detection timer and the half cycle condition satisfaction counter are cleared, respectively, and return to the original state (STEP 1 ).

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

When the peak detection flag is turned on, Gn is set to ± 0.05 g to confirm the half-wave period.
Is repeated until the value reaches Gn ≧ ± 0.05.
Clear peak detection flag when it becomes g, check the G sensor signal period detection timer, said timer and 0.1 ≦
If t.ltoreq.0.25, the G sensor signal cycle detection timer is cleared, the half cycle condition satisfaction counter is incremented by 1 (STEP 7), and the process returns to the original state. Then, as described later, when the counter becomes 2 or more, the operation shifts to pitching or bouncing control operation.

On the other hand, if the timer is less than 0.1 seconds,
If it is greater than 0.25 sec, the G sensor signal cycle detection timer and the half cycle condition satisfaction counter are cleared and the process returns to the original state (STEP 8). Then, since the counter is cleared as described later, the pitching and bouncing control operations are cleared.

When the peakless flag is set, Gn is set to ± 0.0 until the half-wave period ends.
Step 9 is repeated until the weight reaches 5 g, and after completion, the peakless flag is cleared (STEP 10), and thereafter the above operation is repeated.

FIG. 4B shows an operation procedure of suspension control in pitching and bouncing. First, when the half cycle condition satisfaction counter is smaller than 2 or cleared, it is determined that the vehicle is in a normal running state (STEP 11).
When the change-over switch 12 on the side of the cab is in the automatic mode, the damping force of the shock absorber 3A (actuator) on the cab 1 side is set to the software side together with the chassis 2 side (STEP 1).
2) And in the case of normal, only the chassis 2 side is soft
Door, to set the cab 1 side to the normal (STEP1
3).

On the other hand, when the half cycle condition satisfaction counter is 2 or more, the damping force of the shock absorber 3A on the cab 1 side is reduced to the hardware side together with the chassis 2 side when the changeover switch 12 on the cab 1 side is set to the automatic operation. Set (STE
P14) Then, in the case of normal, only the chassis 2 side is set to hard and the cab 1 side is set to normal (STEP 1).
5). Then, after the pitching or bouncing is completed, the half cycle condition satisfaction counter is cleared, the state shifts to a normal running state, and the process returns to STEP11. Hereinafter, the above operation is repeated.

In order to briefly explain the overall suspension control operation of the present embodiment, the present embodiment is divided into a manual mode control operation and an automatic mode control operation. Control circuit 2
At 0A, it is first determined whether or not the hardware switch 11a is ON. If it is ON, it is determined that the hardware setting is a manual operation hardware setting, and the damping of the shock absorber 3A (actuator) on the cab 1 side together with the chassis 2 side. Set force to hard side.

Next, when the hard switch 11a is turned off and the soft switch 11b is turned on, it is determined that the manual setting is a software setting, and the damping force of the shock absorber 3A of the cab 1 together with the chassis 2 is reduced to the software side. Set. When both the hard switch 11a and the soft switch 11b are OFF, the process shifts to the automatic mode control.

In the automatic mode control, as described above, the suspension is set on the chassis side and the cab side respectively with the software, and the vehicle travels. If, for example, pitching / bounce occurs during the traveling, priority is given to the control. The control circuit 20B1 determines this based on the signal of the vertical G sensor 14 and sets both the chassis 2 side and the cab 1 side to hard based on the output control signal. If this occurs, the control circuit 20B2 determines this based on the signal of the G sensor 14 as described above, and sets both the software and the cab 1 to soft on the chassis 2 based on the output control signal. Further, when the vehicle shifts to the high-speed running state by the vehicle speed sensor, the control circuit 20B4 judges this and determines the chassis 2 based on the output control signal.
If the deceleration corresponding to the change state of the vehicle speed per unit time becomes lower than a certain value when the brake switch is turned on, the control circuit 20B4 sets this to the hard side. Is determined to be a nose dive, and both the chassis 2 side and the cab 1 side are set to hardware based on the output control signal.

In this embodiment, the pitch
Chassis side suspension that most affects the suppression of bouncing and bouncing
Always switch to hard for a predetermined time for the damping force of the
However, the cab has some tolerance. Keda
For road conditions or high-speed driving, the cab side
There is no need to set the Spencer hard,
Such as hard intermediate hard and soft considering the steering stability
It may be better to set to normal.

That is, the pitch is generated at the time of pitching or bouncing.
Damping force of the cab suspension based on the control signal
Means for hard setting the key, and a key independent of the control signal.
The damping force of the hub side suspension is constant (normal or har
And a means to maintain the selection, and manually switch the selection.
To select the desired mode
It is possible.

[0038]

As described above, according to the present invention, even in a vehicle in which a suspension is interposed on each of the chassis side and the cab side, it is possible to accurately and reliably pitch and secure a comfortable ride during traveling. Bouncing can be prevented.

Further, according to the present invention, desired or optimal suspension control can be performed in accordance with road conditions, running conditions or personal preferences while suppressing pitching and bouncing. Since it can be performed, the product is further improved and the use value is increased without complicating the configuration. And so on.

[Brief description of the drawings]

FIG. 1 is a time chart of pitching and bouncing control shown in FIG.

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

FIG. 3 is a control block diagram showing an overall configuration of a suspension control mechanism incorporated in the vehicle.

FIG. 4A is a flowchart illustrating a signal generation operation of pitching and bouncing control.

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

[Explanation of symbols]

 Reference Signs List 1 cab 2 chassis 3, 4 suspension 20 control unit 12 auto / normal mode switch

Claims (1)

(57) [Claims] 1. A damping force interposed between a chassis and an axle.
Variable chassis side suspension, chassis and cab
Variable damping cab side suspension interposed between
In the vehicle suspension control method provided with the above, the amplitude of the detection output of the vehicle vertical acceleration becomes equal to or more than a predetermined value within a long wave cycle range substantially corresponding to the resonance cycle of the cab-side suspension under a condition of a certain vehicle speed or more.
The half-wave having an amplitude equal to or larger than the predetermined value is at least 2
The suspension control method according to claim 1, wherein the damping force of the suspension on the cab side and the suspension side on the chassis side is switched to the hard side while the half- wave continues.