JP2818900B2 - Bad road judgment device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a rough road determination for determining whether or not a running road surface is a rough road based on a change in wheel speed (wheel rotation speed) during running of a vehicle. Related to the device.

(Prior Art) In various controls such as traction control and anti-skid control of a vehicle, to perform more appropriate control, it is conceivable to change the control content depending on, for example, whether or not the traveling road surface is rough. .

Conventionally, as a rough road determination device for determining whether such a traveling road surface is a rough road, as described in, for example, Japanese Patent Application Laid-Open No. 64-29636, the calculation of the wheel speeds of different wheels by means of There is known an apparatus which calculates a difference, extracts only a predetermined frequency band component by passing an output of the calculating means through a filter, and determines whether or not the road is a rough road based on the predetermined frequency band component.

In addition, as a rough road determination device, as a configuration other than the above, in the case of a rough road, the wheels vibrate due to unevenness of the road surface, and the vibrations appear in the wheel speed, whereby the time change rate of the wheel speed (wheel Paying attention to the fact that the amplitude of the wheel acceleration vibration (the change over time of the wheel acceleration) exceeds a predetermined threshold value α within a predetermined time, whether or not the number of times that the amplitude exceeds a predetermined threshold value β is larger than a predetermined threshold value β. It is conceivable that a device that checks whether the road is large and determines that the road is bad is large.

(Problems to be Solved by the Invention) However, the latter rough road determination device has the following problems.

That is, the behavior of the wheels changes not only on the rough road, but also due to changes in braking and suspension characteristics (spring constant, damper damping force). In other words, when braking, torque fluctuations occur due to fluctuations in the braking force, and therefore the vibration of the wheel acceleration during braking is
The vibration of the wheel acceleration caused by the rough road is superimposed on the vibration of the wheel acceleration caused by the braking. Such vibration of the wheel acceleration due to the braking naturally occurs during braking by the driver depressing the brake pedal, but is particularly remarkable during braking by traction control or anti-skid control. When the suspension characteristics change, the amplitude and cycle of the wheel vibration change, and the degree of the wheel acceleration vibration changes accordingly.

Therefore, in the latter rough road determination device, when the threshold values α and β are set to predetermined constant values,
When braking or when the suspension characteristics change, accurate rough road determination cannot be performed, and the accuracy of rough road determination decreases.

In view of the above circumstances, an object of the present invention is to provide a rough road determination device that can perform rough road determination with high accuracy even during braking or when suspension characteristics change.

(Means for Solving the Problems) According to a first aspect of the present invention, in order to achieve the above object, a wheel acceleration detecting means for detecting an acceleration of a wheel, and an amplitude of a temporal change of the acceleration detected by the detecting means are provided. The number of times exceeding a predetermined threshold α within a predetermined time is equal to a predetermined threshold β
Bad road determining means for determining whether the road is rough or not based on whether the road is larger or not; braking / non-braking detecting means for detecting whether braking is being performed or non-braking; Threshold value changing means for changing the threshold value α to be larger during braking than during non-braking in response to the output of the means.

The amplitude of the change over time of the wheel acceleration means the amplitude of the change over time of the wheel acceleration centered on the vehicle body acceleration.For example, when a value obtained by subtracting the wheel acceleration from the actual wheel acceleration is defined as a true wheel acceleration, It means the true width of the change over time of the true wheel acceleration (the same applies to the following second and third inventions).

Various modes are conceivable for the mode of the rough road determination, for example, which wheel acceleration is to be considered to perform the rough road determination, and is not limited to a specific mode (the following third and fourth embodiments). The same applies to the invention of No. 4.)

The term “during braking” or “under braking” basically means whether or not the brake is operating. For example, when an anti-skid control device is provided, whether or not the anti-skid control is being performed is determined. Or, if a traction control device is provided, it may mean whether or not braking is being performed in traction control (also in the second invention described below). the same).

According to a second aspect of the present invention, to achieve the above object, a wheel speed change detecting means for detecting a change in wheel speed, and whether or not a rough road is detected based on the wheel speed change detected by the detecting means. Bad road determination means for determining, braking / non-braking detection means for detecting whether braking or non-braking is being performed, and receiving the output of the detection means to apply the wheel to the rough road determination means during braking. Wheel speed determining means for determining whether or not the road is rough using the rear wheel speed as the speed.

The means for determining a bad road in the second invention may be any means that makes a determination of a bad road based on a change in wheel speed. The determination is not limited to the determination based on whether the number of times exceeding α is larger than the threshold value β.

According to a third aspect of the present invention, to achieve the above object, a wheel acceleration detecting means for detecting a wheel acceleration, and an amplitude of a temporal change of the acceleration detected by the detecting means is set to a predetermined threshold value within a predetermined time. Bad road determining means for determining whether or not the road is a bad road based on whether the number of times exceeding α is larger than a predetermined threshold value β, and spring constant detection for detecting a change in the spring constant of the suspension Means, and threshold changing means for changing the predetermined threshold β so as to increase when the spring constant increases upon receiving the output of the spring constant change detecting means. .

According to a fourth aspect of the present invention, to achieve the above object, a wheel acceleration detecting means for detecting a wheel acceleration, and an amplitude of a temporal change of the acceleration detected by the detecting means is set to a predetermined threshold value within a predetermined time. bad road determining means for determining whether or not the road is a rough road based on whether or not the number of times exceeding α is greater than a predetermined threshold value β; and a damping force for detecting a change in the damper damping force of the suspension. And a threshold changing means for receiving the output of the damping force change detecting means and changing the predetermined threshold α so as to decrease when the damping force increases. And

(Operation) As described above, at the time of braking, the amplitude of the temporal change in wheel acceleration (wheel acceleration vibration) increases. Therefore, by changing the threshold α during braking to be larger than that during non-braking as in the first invention, the threshold α is not affected by the increase in the amplitude of the wheel acceleration vibration caused by the braking, A highly accurate rough road determination can be performed.

In general, the speed of the driving wheels is affected by the fluctuation of the driving torque. Therefore, when making a bad road determination based on a change in wheel speed, it is desirable to make a determination based on a change in driven wheel speed that is not affected by such a change in drive torque. However, the braking force of the wheels is set so that the front wheels are generally larger in order to enhance the braking performance, because the load movement at the time of braking occurs and the front wheels have a larger grounding load. Is more affected by the braking force fluctuation, or the front wheels are more likely to lock, and if locked, vibrations appearing at the wheel speed due to unevenness of the road surface disappear, and it becomes impossible to determine a bad road. Therefore, as described in the second aspect of the present invention, whether the rear wheel is a driving wheel or a driven wheel, a bad road determination is performed based on a change in the rear wheel speed during braking, so that the front wheel is determined. Compared to the case based on speed change, it is possible to avoid the situation where it is impossible to determine a bad road due to the locking phenomenon of wheels due to braking, and it is less affected by wheel speed changes due to braking, and more accurate The rough road determination of high can be performed.

When the spring constant of the suspension characteristics is increased, the cycle of the wheel vibration becomes smaller, and accordingly, the cycle of the wheel acceleration vibration becomes smaller. Therefore, when the spring constant is increased as in the third invention, the threshold value β is increased, so that the threshold value β is not affected by the change in the cycle of the wheel acceleration vibration due to the change in the spring constant. Road determination can be performed.

When the damping force of the damper in the suspension characteristics is increased, the amplitude of the wheel vibration decreases, and the amplitude of the wheel acceleration vibration decreases accordingly. Therefore, the third
When the damping force is increased as in the invention of
Makes it possible to perform a highly accurate rough road determination without being affected by the change in the amplitude of the wheel acceleration vibration due to the change in the damping force.

(Embodiment) Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

First, an embodiment of the first invention will be described. This embodiment detects the acceleration of the left and right front wheels that are driven wheels in an FR vehicle, and the number of times that the amplitude of each acceleration vibration exceeds a predetermined threshold α within a predetermined time is larger than a predetermined threshold β. The anti-skid control determines whether the vehicle is on a rough road if any one of the left and right front wheels is larger than the threshold value β. It is intended to be changed.

In this embodiment, as shown in FIG. 1, a wheel acceleration detecting means 2 for detecting an acceleration of a wheel, and an amplitude of a temporal change of the acceleration detected by the detecting means 2 is set to a predetermined threshold value within a predetermined time. bad road determining means 4 for determining whether or not the vehicle is on a rough road based on whether or not the number of times exceeding α is greater than a predetermined threshold value β; Braking / non-braking detecting means 6 for detecting the threshold value α, and the predetermined threshold value α during braking in response to the output of the detecting means 6 is higher than during non-braking.
And a threshold value changing means 8 for changing the wheel acceleration to a large value. The wheel acceleration detecting means 2 employs a detecting means for obtaining the acceleration of the left and right driven wheels based on the rotational speeds of the axles of the left and right driven wheels. As the braking / non-braking detecting means, for example, a detecting means for detecting whether or not anti-skid control is being performed based on a control signal from the anti-skid controlling means is used.

Next, the rough road determination procedure in this embodiment will be described with reference to FIG.
This will be described with reference to FIGS. 6 and 7.

FIG. 5 is a flowchart showing a rough road determination procedure for the left front wheel. As shown in FIG. 5, first, in S1, it is determined whether or not a timer is equal to or more than a predetermined value, that is, whether a predetermined time (for example, 0.7 seconds) has elapsed. It is determined whether or not the acceleration has not elapsed, and if not, an acceleration DWFL of the left front wheel is calculated in S2. Calculation of DWFL is determined from the current left wheel speed WFL _n by subtracting the left front wheel speed WFL _n-1 of the last time.

DWFL = WFL _n -WFL _n-1 Then, an offset correction of the left front wheel acceleration based on the following equation in S3.

This offset correction is for obtaining the above-described true wheel acceleration. That is, the actual wheel acceleration obtained in S2 includes the acceleration of the vehicle body, and therefore, the offset correction for obtaining the true wheel acceleration is performed by subtracting the vehicle acceleration from the actual wheel acceleration. In the above equation, the vehicle body acceleration is represented by (WFL _n -WFL _n-4 ) / 4. This is because when considering the relationship between the wheels and the vehicle body, the wheels first start to rotate, whereby the vehicle body starts to move. That is, the vehicle body starts to move with a delay with respect to the wheels, and the delay corresponds to almost four cycles of the flow of the rough road determination in the present embodiment (flow processing cycle: 14 msec;
msec). Therefore, the average of the actual wheel accelerations up to four cycles before the present is set as the vehicle body acceleration.

When the true wheel acceleration DWFL is obtained as described above, it is determined in S4 whether or not the anti-skid control is being performed.
In step S5, the threshold value α is set to α = 0.70G.
To set the threshold α to α = 0.50G.

Subsequently, the number of times PCFL (left front wheel peak count) in which the true wheel acceleration DWFL obtained in S3 exceeds the threshold value α is counted. That is, when the vibration of the DWFL (change with time) is as shown in FIG. 6, the peak of the vibration of the DWFL is + α,
Count the number of times PCFL exceeds -α. In this count, as shown in FIG. 6, the number of peaks PCFL exceeding + α, −α is counted, and the count is performed when the peaks alternately exceed + α, −α. For example, if one peak exceeds + α and the next peak does not exceed −α and also exceeds + α, the second peak exceeding + α is not counted. When the wheel acceleration vibrates due to a bad road, it should generally vibrate alternately in the (+) direction and the (-) direction. Therefore, only when + α and -α alternately exceed as described above. By performing the counting, it is possible to perform a rough road determination with higher accuracy.

Specifically, in S7, it is determined whether or not the DWFL in S3 is 0 or more. If it is 0 or more, it is determined in S8 whether or not the DWFL is greater than + α. If not, the flow is terminated. Then S9
It is determined whether or not the left front wheel peak flag PFFL is 1. The last time PFFL was set to 1, that is,
Since the DWFL has exceeded -α, it means that the PCFL has been counted once. The fact that the PFFL has been reset, ie, has been reset, means that since the DWFL has exceeded + α last time, the PCFL has been counted once. If the PFFL is 1, the PCFL is counted once because it exceeded -α the previous time.
L is counted and PCFL is increased by one, and then PFFL is set to 0 in S11, and the flow ends. In S9, PFFL
If it is not 1, it means that it exceeds + α following the previous time, and in order to prevent one peak from being counted twice, it is not counted on the previous (-) side. Without counting PCFL, in order to prevent the (+) side from counting again once more
Proceed to S11 and end the flow.

Further, if DWFL is less than 0 in S7, it is determined whether or not DWFL is smaller than -α in S12.If it is not small, the flow is terminated.If it is small, the same as S9 to S11 is performed. Advance the procedure based on the idea. That is, first, it is determined whether or not PFFL is 0 in S13, and if it is 0, P is determined in S14.
The CFL is counted once, and then the PFFL is set to 1 in S15, and the flow ends. If the PFFL is not 0 in S13, the process proceeds to S15 without counting the PCFL and ends.

The procedure of S1 to S15 is repeated as described above, and when the predetermined time has elapsed, the timer is determined to be equal to or more than the predetermined value in S1, so the process proceeds to S16, the timer is reset, and the PCFL is set in advance in S17. It is determined whether the threshold value is larger than a threshold value β (for example, β = 10). If not, the left front wheel rough road flag AKRFL is set to 0 in S18, and then the PCFL is set in S19.
Is set to 0 and the flow ends. If PCFL is larger than β in S17, the left front wheel rough road flag AKRFL is determined in S18.
Is set to 1 and the process proceeds to S19 to end the flow.

The above is the rough road determination flow for the left front wheel, but the rough road determination is also performed for the right front wheel in a similar flow as before. Then, it is determined whether or not the final road is a rough road, as shown in S21 of FIG. 7, when either the rough road flag AKRFL of the left front wheel or the rough road flag AKRFL of the right front wheel is set to 1. If this is the case, it is determined that the road is bad.

In the above embodiment, either AKRFL is one of AKRFR.
Is determined as a bad road, but when both of them are 1, it may be determined that the road is bad, or the rough road may be determined in a similar manner based on the acceleration of the driving wheels. The determination may be made, or the bad road may be determined as appropriate based on, for example, the acceleration of all four wheels.

Further, in the above-described embodiment, the change of the threshold value α is performed based on whether the anti-skid control is being performed or not, but the threshold α is determined based on whether the vehicle is simply braking, that is, whether the brake pedal is depressed. The change may be made, or the change may be made based on whether or not the traction control is being performed.

Further, the change of the threshold value α is not limited to being performed alternately depending only on whether or not the anti-skid control is being performed at the end, and may be changed in multiple steps based on other control factors. Good, or may be changed continuously.

The threshold value α is different from the case of the amplitude in the (+)
The magnitude may be different from that in the case of the amplitude in the direction, and when the threshold value α is changed in the larger direction, the larger width may be different between the (+) side and the (−) side. Alternatively, only one of the (+) side and the (-) side may be made larger.

In the above embodiment, the threshold α is changed to be larger during the anti-skid control than during the non-skid control. Without being affected by changes in the amplitude of wheel acceleration vibration caused by braking with its anti-skid control,
A highly accurate rough road determination is performed.

Next, an embodiment of the second invention will be described. This embodiment detects the acceleration of each of the four wheels for an FR vehicle in which the front wheel is a driven wheel and the rear wheel is a drive wheel, and based on the acceleration of the left and right front wheels which are the driven wheels when anti-skid is not controlled. Same as the invention (however, the threshold value α is constant)
Rough road determination is performed, and during anti-skid control, rough road determination is performed based on the acceleration of the left and right rear wheels.

In this embodiment, as shown in FIG. 2, a wheel speed change detecting means 10 for detecting a change in wheel speed, and whether or not a rough road is detected based on a change in left wheel speed detected by the detecting means 10 is determined. Bad road determining means 12 for determining; braking / non-braking detecting means 6 for detecting whether braking is being performed or non-braking; Wheel speed specifying means 14 for determining whether or not the vehicle is on a bad road by using the rear wheel speed as the wheel speed. The wheel speed change detecting means 2 calculates the wheel acceleration of each of the four wheels. A means for detecting whether or not the anti-skid control is being performed is used as the braking / non-braking detecting means 6 as in the first embodiment of the present invention. As in the embodiment of the first invention, the amplitude of the acceleration of the wheel is within a predetermined time. Number exceeding the value α is used to perform a rough road determination based on whether or not is greater than the threshold value beta.

Next, a rough road determination procedure in this embodiment will be described with reference to FIGS. 8 and 9. FIG.

The determination of a bad road in this embodiment is carried out in the same way as in the embodiment of the first invention (however, the threshold value α is fixed) for each wheel. It is determined whether or not the number of times exceeding the threshold value is larger than a threshold value β.
To FIG. 8 shows such a bad road flag AK at the left front wheel.
It is a flowchart which shows the procedure of whether or not to make one RFL, and it is determined whether the bad road flag is set to 1 also about another wheel similarly to this flowchart. Note that the flowchart of FIG. 8 can be easily understood by referring to the description of the flowchart of FIG.

Then, as shown in the flowchart of FIG. 9, it is determined whether or not the anti-skid control is being performed in S39, and if the vehicle is not being controlled, the process proceeds to S40. Therefore, the determination is made based on the left and right front wheel acceleration. That is, if either the left front wheel rough road flag AKRFL or the right front wheel rough road flag AKRFR is 1, it is determined that the road is rough and the rough road flag is determined.
Set AKRF. If the anti-skid control is being performed in S39, the process proceeds to S41, where a determination is made based on the acceleration of the left and right rear wheels, that is, both the left rear wheel bad road flag AKRRL and the right rear wheel bad road flag AKRRR become 1. If so, the road is determined to be a bad road and a bad road flag AKRF is set.

In the above-described embodiment, the bad road flag AKRRL and AKRRR of the left and right rear wheels are determined to be a bad road only when they are set during the anti-skid control, but the bad road is determined when only one of them is set. The road may be determined.

In addition, during anti-skid non-control, the determination may be made based on the acceleration of either the front wheel or the rear wheel.

In other respects, various modifications can be made as in the case of the embodiment of the first invention.

In the above-described embodiment, the bad road determination is performed based on the change in the front wheel speed of the rear wheel having a smaller braking force during the braking with the anti-skid control and, therefore, having less influence on the wheel speed change due to the braking force vibration. In the road determination, adverse effects due to braking with anti-skid control are small, and a highly accurate rough road determination can be performed.

Next, an embodiment of the third invention will be described. In this embodiment, in an FR vehicle having an air suspension in which a spring constant can be selected to be either large or small by a switch operation, the wheel acceleration of each of the left and right front wheels that are driven wheels exceeds a predetermined threshold α within a predetermined time. It is determined whether or not the number of times the vehicle has exceeded a predetermined threshold value β. If any one of them exceeds the threshold value β, the road is determined to be a bad road, and the spring constants of the left and right front wheel suspensions can be increased. For example, the threshold value β is changed to a large value.

In this embodiment, as shown in FIG. 3, a wheel acceleration detecting means 2 for detecting the acceleration of a wheel, and an amplitude of a temporal change of the acceleration detected by the detecting means 2 is a predetermined threshold value within a predetermined time. bad road determining means 4 for determining whether or not the road is a rough road based on whether or not the number of times exceeding α is greater than a predetermined threshold β; and a spring constant for detecting a change in the spring constant of the suspension. Change detecting means 16 and a threshold changing means 18 which receives the output of the spring constant change detecting means 16 and changes the predetermined threshold β so as to increase when the spring constant increases, As the wheel acceleration detection means 2, acceleration detection means for left and right front wheels which are driven wheels is used,
As the spring constant change detecting / reducing means 16, means for receiving a signal from a spring constant changing switch of the suspension and detecting whether the spring constant of the suspension is set to any of large or small is used.

Next, a procedure for determining a bad road in this embodiment will be described with reference to FIG.

In this embodiment, for the left front wheel, S42 to S53 in FIG.
As shown in (1), the number of times PCFL in which the true front left wheel acceleration DWFL exceeds the threshold value α is counted in the same manner as in the embodiment of the first invention (however, the threshold value α is fixed). Then, when the timer counts the number of PCFLs exceeding the threshold value α within the predetermined time period after the timer becomes equal to or more than the predetermined value in S42,
In the timer is reset, it is determined whether the spring constant of the suspension is less or is larger in S55, the threshold beta in S56 if small and beta _1, threshold beta in S57 if large Β ₂ (β ₂ > β ₁ ). Then, the PCFL is compared with β set according to the magnitude of the spring constant in S58, and the PCFL
Is smaller than β, the left front wheel rough road flag AKRFL is set to 0 in S59, and if larger than β, the left front wheel rough road flag AKRFL is set to 1 in S60.
And set PCFL to 0 in S61.

In addition, bad road determination is performed for the right front wheel in exactly the same manner as described above, and the right front wheel bad road flag AKRFR is set to 1 or 0.
To

Then, the final rough road determination is made by AK as in the first invention.
If either RFL or AKRFR is 1, it is determined as a bad road.

In the above embodiment, since the spring constant of the suspension can be changed in two stages, β is also changed in two stages in accordance with the spring constant. Β may be changed in three or more steps, and if the spring constant is continuously changeable, β may be changed continuously. Further, the spring constant change detecting means 16 may detect the spring constant itself.

In other respects, various modifications can be made as in the case of the embodiment of the first invention.

In the above embodiment, when the spring constant increases, the threshold value β is increased. Therefore, the threshold value β is increased without being affected by the change in the wheel acceleration vibration (change in the cycle) caused by the change in the spring constant. Road determination can be performed.

Next, an embodiment of the fourth invention will be described. This embodiment is an FR equipped with a damping force variable suspension capable of selecting the damping force of the tamper to be large or small by operating a switch.
For each of the left and right front wheels that are driven wheels in the vehicle, it is checked whether the number of times that the wheel acceleration exceeds a predetermined threshold value α within a predetermined time is larger than a predetermined threshold value β, and if any one of them, If the threshold value β is exceeded, the road is determined to be a bad road, and if the damping force of the left and right front wheel suspensions increases, the threshold value α is changed to a small value.

In this embodiment, as shown in FIG. 4, a wheel speed detecting means 2 for detecting the acceleration of a wheel, and an amplitude of a temporal change of the acceleration detected by the detecting means 2 is set to a predetermined threshold value within a predetermined time. bad road determining means 4 for determining whether the road is a bad road based on whether the number of times exceeding α is greater than a predetermined threshold value β, and a damping force for detecting a change in the damping force of the suspension Change detecting means 20, and a threshold value changing means 22 receiving the output of the damping force change detecting means 20 and changing the predetermined threshold value α so as to decrease when the damping force increases, As the wheel acceleration detecting means 2, acceleration detecting means for left and right front wheels which are driven wheels is used, and as the damping force change detecting means 20, a signal from a suspension damping force change switch receives a signal to determine whether the suspension damping force is large or small. Is set And using means for detecting.

Next, a procedure for determining a bad road in this embodiment will be described with reference to FIG.

In this embodiment, for the left front wheel, S62 to S76 in FIG.
As shown in FIG. 7, the number of times PCFL in which the true left front wheel acceleration DWFL exceeds the threshold value α is counted in the same manner as in the first embodiment. However, unlike the first invention, as shown in S65, S66, S67, it is determined whether the damping force of the damper is small or a large, the threshold value alpha and alpha ₂ if small, large In this case, the threshold α is set to α ₁ (α ₁ <α ₂ ), and the number of times PC exceeds the α based on α set according to the magnitude of the damping force.
Count FL.

Then, when the timer counts the number of times the PCFL exceeds the threshold value α within the predetermined time after the timer has exceeded the predetermined value in S62, the timer is reset in S77 and the PCFL is reset in S78.
Is compared with β.If PCFL is smaller than β, the left front wheel rough road flag AKRFL is set to 0 in S79.If PCFL is larger than β, the left front wheel rough road flag AKRFL is set to SFL in S80. I do.

In addition, bad road determination is performed for the right front wheel in exactly the same manner as described above, and the right front wheel bad road flag AKRFR is set to 1 or 0.
To

Then, the final rough road determination is made by AK as in the first invention.
If either RFL or AKRFR is 1, it is determined as a bad road.

In the above embodiment, since the damping force of the suspension can be changed in two stages, α is also changed in two stages in accordance with the damping force. May be changeable in three or more steps, and if the damping force can be changed continuously, α may be changed continuously. Further, the means for detecting the change in damping force may be a means for detecting the damping force itself.

In other respects, various modifications can be made as in the case of the embodiment of the first invention.

In the above embodiment, when the damping force increases, the threshold value α is reduced, so that the threshold value α is not affected by a change in wheel acceleration vibration (a change in amplitude) caused by a change in the damping force.
A highly accurate rough road determination can be performed.

(Effects of the Invention) As described in detail above, in the first invention, the threshold value α is changed to be larger during braking than during non-braking, so that the amplitude of wheel acceleration vibration caused by braking increases. Irrespective of the road condition, it is possible to perform a highly accurate rough road determination.

According to the second aspect of the present invention, since the rough road determination is performed based on the speed change of the rear wheel during braking, the vehicle is more affected by the wheel speed change caused by the braking than the case based on the speed change of the front wheel. Without this, highly accurate rough road determination can be performed.

Further, in the third aspect, when the spring constant increases, the threshold value β is changed to a large value, so that the accuracy is not affected by the change in the cycle of the wheel acceleration vibration caused by the change in the spring constant. The rough road determination of high can be performed.

Further, in the fourth invention, when the damper damping force becomes large, the threshold value α is changed to a small value, so that the threshold value α is not affected by the change in the amplitude of the wheel acceleration vibration caused by the change in the damping force. A highly accurate rough road determination can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the first invention, FIG. 2 is a block diagram showing one embodiment of the second invention, and FIG. 3 is a block diagram showing one embodiment of the third invention. FIG. 4 is a block diagram showing an embodiment of the fourth invention, FIGS. 5 and 7 are flowcharts showing a procedure for determining a bad road in the embodiment of the first invention, and FIG. FIGS. 8 and 9 are flowcharts showing a procedure for determining a bad road according to the embodiment of the second invention. FIG. 10 is a flowchart showing a procedure for determining a bad road according to the embodiment of the third invention. FIG. 11 is a flowchart showing a rough road determination procedure according to the embodiment of the fourth invention. 2 wheel acceleration detecting means 4, 12 bad road determining means 6 braking / non-braking detecting means 8, 22 threshold value α changing means 10 wheel speed change detecting means 14 wheel speed identification Means 16: Spring constant change detecting means 18: Threshold value β changing means 20: Damping force change detecting means

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toru Onaka 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Prefecture Inside Mazda Co., Ltd. (56) References JP-A-3-182865 (JP, A) JP-A Heisei 3-227764 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) B60T 8/58

Claims (4)

(57) [Claims] 1. A wheel acceleration detecting means for detecting the acceleration of a wheel, and a predetermined threshold value indicates the number of times that the amplitude of the temporal change of the acceleration detected by the detecting means exceeds a predetermined threshold value α within a predetermined time. Bad road determining means for determining whether or not the road is rough based on whether the value is greater than a value β, braking / non-braking detecting means for detecting whether braking is being performed or not being braked,
A bad road determination device comprising: threshold value changing means for receiving the output of the detection means and changing the threshold value α to be larger during braking than during non-braking. 2. A wheel speed change detecting means for detecting a change in wheel speed, a bad road determining means for determining whether or not the vehicle is on a bad road based on a wheel speed change detected by the detecting means. Braking / non-braking detection means for detecting whether the vehicle is being braked or not, and during braking in response to the output of the detection means, the rough road determination means uses the rear wheel speed as the wheel speed on a rough road. A bad road determining device for determining whether or not there is a vehicle speed. 3. A wheel acceleration detecting means for detecting an acceleration of a wheel, and a predetermined threshold value indicates a number of times that the amplitude of the temporal change of the acceleration detected by the detecting means exceeds a predetermined threshold value α within a predetermined time. Bad road determination means for determining whether or not the road is rough based on whether the value is greater than the value β, spring constant change detection means for detecting a change in the spring constant of the suspension,
Threshold value changing means for changing the predetermined threshold value β so as to increase when the spring constant increases in response to the output of the spring constant change detecting means. apparatus. 4. A wheel acceleration detecting means for detecting an acceleration of a wheel, and a predetermined threshold value indicates a number of times that the amplitude of the temporal change of the acceleration detected by the detecting means exceeds a predetermined threshold value α within a predetermined time. Bad road determining means for determining whether or not the road is rough based on whether the value is greater than a value β, damping force change detecting means for detecting a change in damper damping force of the suspension, And a threshold changing means for changing the predetermined threshold α so as to be reduced when the damping force increases in response to the output of the means.