JP3190001B2 - Vehicle body speed estimation device and traction control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle speed estimating device for estimating a vehicle speed used for grip control of driving wheels, and a traction control device provided with the vehicle speed estimating device.

[0002]

2. Description of the Related Art A vehicle speed used for control in a traction control device of a vehicle or the like is generally obtained based on a rotation speed of a driven wheel (driven wheel speed). This is because the drive wheels may slip against the road surface due to excessive engine torque, and the slip causes the rotation speed of the drive wheels (drive wheel speed) to become in proportion to the vehicle body speed. This is because a proportional relationship with the vehicle speed is maintained without occurrence.

[0003]

However, even when the vehicle speed is obtained based on the speed of the driven wheel, the driven wheel skids against the road surface when the driven wheel is locked by the braking operation. The proportional relationship between the speed and the vehicle speed may be broken, and an error may occur between the estimated vehicle speed and the actual vehicle speed.

The present invention has been made in view of the above circumstances, and has as its object to estimate an accurate vehicle speed when a driven wheel is locked and to perform accurate traction control based on the vehicle speed. And

[0005]

According to one aspect of the present invention, there is provided a vehicle speed estimating apparatus for a vehicle, comprising:
Driven wheel speed, which is the average of left and right driven wheel speeds
Pseudo wheel speed calculating means for calculating a degree as a pseudo wheel speed, a change amount calculating means for calculating a difference between a driven wheel speed with respect to a previous value of the pseudo wheel speed and comparing with a threshold value, and the change amount calculating means When it is determined that the difference exceeds the threshold value, pseudo wheel speed correction means for correcting the pseudo wheel speed by subtracting or adding a predetermined value to the pseudo wheel speed, and when the difference exceeds the threshold value, Selecting means for selecting, as the vehicle speed, the pseudo wheel speed corrected by the pseudo wheel speed correction means, instead of the driven wheel speed, road surface friction coefficient estimating means for estimating a road surface friction coefficient of a road on which the vehicle travels, And a threshold / predetermined value correcting means for correcting the threshold value and the predetermined value based on a road surface friction coefficient.

According to a second aspect of the present invention, there is provided a vehicle body speed estimating apparatus for a vehicle, wherein the selecting means comprises:
Until the difference the change amount calculation means has calculated Ru exceeds the threshold value continuously for a predetermined number of times and said driven wheel speed vehicle speed
And the threshold value is set to a threshold value for a predetermined number of consecutive times.
If it exceeds, the pseudo wheel speed corrected by the pseudo wheel speed correction means is selected as the vehicle body speed.

According to a third aspect of the present invention, in the vehicle body speed estimating apparatus, the left driven wheel speed is set as a left pseudo wheel speed.
Pseudo wheel speed calculating means for calculating the right driven wheel speed as the right pseudo wheel speed, respectively, and left and right pseudo wheel speeds.
A change amount calculating means for respectively calculating the difference between the left and right driven wheel speeds with respect to the previous value and comparing the difference with the threshold value, and when the change amount calculating means determines that the difference exceeds the threshold value, a pseudo wheel speed correcting means for subtracting or adding a predetermined value to the pseudo wheel speed, if the difference between at least one of the driven wheel speed exceeds the threshold value left, the average value of the right sub <br/> wheel speed Alternatively, selection means for selecting the average value of the left and right pseudo wheel speeds as the vehicle body speed, road surface friction coefficient estimation means for estimating the road surface friction coefficient of the road on which the vehicle travels, and the threshold value based on the road surface friction coefficient And a threshold / predetermined value correcting means for correcting the predetermined value.

According to a fourth aspect of the present invention, there is provided a traction control device including the vehicle body speed estimating device according to the first , second, or third aspect , wherein the detection is performed based on the estimated vehicle body speed. And an engine output control means for controlling the output of the engine in accordance with the slip state of the driven wheels.

[0009]

According to the first aspect of the present invention, when the locked or unlocked of the driven wheel has not occurred, the left driven wheel speed is set.
And the driven wheel speed, which is the average of the right driven wheel speeds, is selected as the vehicle speed. The driven wheel speed is referred to as a pseudo wheel speed.
When the difference of the driven wheel speed with respect to the previous value of the pseudo wheel speed calculated by the pseudo wheel speed calculation means , that is, the change amount exceeds the threshold value due to the locking or unlocking of the driven wheel, the pseudo wheel speed is set to the predetermined value. It is corrected by subtracting or adding the value. When the difference of the driven wheel speed with respect to the pseudo wheel speed, that is, the amount of change exceeds the threshold value, the corrected pseudo wheel speed is selected as the vehicle speed instead of the driven wheel speed. As a result, it is possible to always appropriately estimate the vehicle speed regardless of the locked state of the driven wheels. Since the reference value and the predetermined value are corrected based on the road surface friction coefficient, the accuracy of estimating the vehicle speed is improved.

According to the second aspect of the present invention, even if the driven wheel speed fluctuates due to noise and the difference between the driven wheel speed and the pseudo wheel speed, that is, the amount of change temporarily exceeds the threshold value, it does not affect the vehicle speed. Does not affect estimation.

According to the third aspect of the invention, the left and right driven wheels are provided.
Is locked or unlocked.
The vehicle speed can be accurately estimated.

According to the configuration of the fourth aspect, the output of the engine is controlled in accordance with the slip state of the drive wheel detected based on the estimated vehicle speed, and excessive slip of the drive wheel is suppressed.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 to 8 show a first embodiment of the present invention. FIG. 1 is a schematic configuration diagram of a vehicle provided with a traction control system, FIG. 2 is a block diagram of a control system, and FIG.
4 is a block diagram showing a circuit configuration of the electronic control unit, FIG.
5 is a block diagram of a vehicle speed calculation means, FIG. 5 is a first diagram of a flowchart of vehicle speed estimation, FIG. 6 is a second diagram of a flowchart of vehicle speed estimation, FIG. 7 is a flowchart of a subroutine of steps S1 to S3. 8 is a graph showing the vehicle speed.

As shown in FIG. 1, this vehicle is a front-wheel drive vehicle, and includes a pair of left and right driven wheels W _FL and W _FR driven by an engine E and a pair of right and left driven wheels W _RL and W _RR . with which, the drive wheels W _FL, together with the W _FR is provided with driven wheel speed detecting means 1 _FL, 1 _FR, the follower wheels W _RL, W _RR
Is provided with driven wheel speed detecting means 1 _RL and 1 _RR .

The steering wheel 2 is provided with a steering angle detecting means 3 for detecting a steering angle δ, and a lateral acceleration detecting means 4 for detecting a lateral acceleration LG is provided at an appropriate position on the vehicle body. A throttle valve 7 connected to a pulse motor 6 and driven to open and close is provided in an intake passage 5 of the engine E.

The driving wheel speed detecting means 1 _FL , 1 _FR , the driven wheel speed detecting means 1 _RL , 1 _RR , the steering angle detecting means 3, the lateral acceleration detecting means 4 and the pulse motor 6 comprise an electronic control unit having a microcomputer. Connected to U.

FIG. 2 is a flowchart showing the operation of a signal from each detecting means based on a control program in order to suppress the excessive slip when the excessive slip of the drive wheels W _FL and W _FR is detected. Reference numeral 6 denotes an electronic control unit U for driving the throttle valve 7 to control the output of the engine E. The electronic control unit U includes a central processing unit (CPU) 21 for performing the arithmetic processing, a read-only memory (ROM) 22 storing the control program and data such as various maps, and an output of each of the detecting means. A random access memory (RAM) 23 for temporarily storing signals and calculation results; and each of the above-mentioned detecting means, ie, driving wheel speed detecting means 1 _FL , 1 _FR , driven wheel speed detecting means 1 _RL ,
1 _RR , an input unit 24 to which the steering angle detecting means 3 and the lateral acceleration detecting means 4 are connected, and an output unit 25 to which the pulse motor 6 is connected. Thus, the electronic control unit U calculates various signals input from the input unit 14 and data stored in the read-only memory 22 by the central processing unit 21 based on a control program described later. Then, the pulse motor 6 is driven via the output unit 25. As a result, the throttle valve 7 is controlled, the output of the engine E changes, and excessive slip of the drive wheels W _FL , W _FR is suppressed.

Next, an outline of the traction control system will be described with reference to FIG.

The output signals VWDL and VWDR of the left and right driving wheel speed detecting means 1 _FL and 1 _FR are input to the driving wheel speed calculating means 31, where the output signals VWDL and VWDR of the two driving wheel speed detecting means 1 _FL and 1 _FR are output. Of the driving wheel speed V
WNHOS is required. The output signals VWNL and VWNR of the left and right driven wheel speed detectors 1 _RL and 1 _RR , the lateral acceleration LG output by the lateral acceleration detector 4, the actual yaw rate Y output by an actual yaw rate / rotational vibration value calculator 33 described later, and The longitudinal grip force FG output from the longitudinal grip force calculating means 34 described later is input to the vehicle speed calculating means 32, where the vehicle speed VVN is obtained. The function of the vehicle speed calculating means 32 is shown in the block diagram of FIG.
This will be described later in detail based on the flowchart of FIG. Further, the output signals VWNL and VWNR of the left and right driven wheel speed detecting means 1 _RL and 1 _RR are input to the actual yaw rate / rotational vibration value calculating means 33, where the output signals VWNL and VWNL of the driven wheel speed detecting means 1 _RL and 1 _RR are output. The actual yaw rate Y and the rotational vibration value ΔV are obtained based on the driven wheel speed difference that is the deviation of VWNR.

The vehicle speed VVN obtained by the vehicle speed calculation means 32 is input to the front / rear grip force calculation means 34, where the front / rear grip force FG is calculated as a time differential value of the vehicle speed VVN.

The longitudinal grip force FG output by the longitudinal grip force calculating means 34 and the lateral acceleration LG of the vehicle output by the lateral acceleration detecting means 4 are input to the grip control means 35, where the longitudinal grip force FG and the lateral acceleration LG are output. The total grip force TG is obtained as the vector sum of

The steering angle δ output from the steering angle detecting means 3 and the vehicle speed VVN output from the vehicle speed calculating means 32 are input to a reference yaw rate calculating means 36, where the yaw rate that the vehicle should originally generate in accordance with the driving state The reference yaw rate Y _REF is obtained. Normative yaw rate calculation means 3
6 outputs the reference yaw rate Y _REF and the actual yaw rate
The actual yaw rate Y output from the rotational vibration calculating means 33 is input to the steering control means 37, where it is determined whether the vehicle is in an oversteer state or an understeer state.

The rotation vibration value ΔV output from the actual yaw rate / rotation vibration value calculation means 33 is input to the rough road control means 38, where it is determined whether or not the road is rough based on the magnitude of the rotation vibration value ΔV. .

The drive wheel speed VWNHOS output by the drive wheel speed calculation means 31 and the vehicle speed VVN output by the vehicle speed calculation means 32 are input to the target slip ratio calculation means 39, where the drive wheel speed VWNHOS and the vehicle speed VVNOS are input.
When the slip ratio of the drive wheels W _FL and W _FR calculated from the above exceeds a predetermined value, a target slip ratio which is a target value for reducing the slip ratio of the drive wheels W _FL and W _FR is obtained. At this time, the total grip force TG output by the grip control means 35, the steering state output by the operation control means 37, and the road surface state output by the rough road control means 38,
The target slip ratio is corrected.

That is, when the total grip force TG is large, the target slip ratio is corrected upward, and the drive wheels W _FL ,
Sporty running is made possible without damaging the slip control function of the W _FR. The target slip ratio is also corrected upward on a bad road where the drive wheels W _FL and W _FR are unlikely to slip. Further, since the vehicle is a front-wheel drive vehicle, the target slip ratio is corrected upward when the vehicle is in the oversteer state, and the target slip ratio is corrected downward when the vehicle is in the understeer state. This prevents the vehicle from turning in an undesirable direction.

The engine output control means 40 drives the pulse motor 6 based on the target slip rate output from the target slip rate calculation means 39 to drive the throttle valve 7.
The output of the engine E is reduced by adjusting the opening of the engine E. As a result, the drive wheels W _FL, converge the slip rate of the W _FR is the target slip ratio, the driving wheels W _FL, excess slip of W _FR is suppressed.

Next, the function of the vehicle speed calculating means 32 in the block diagram of FIG. 3 will be described.

As shown in FIG. 4, the vehicle speed calculating means 32
Is a turning state determining means M1 that outputs a driven wheel speed outside the turning as a vehicle body speed when the vehicle is in a predetermined turning state.
A simulated wheel speed calculating means M2 for calculating a simulated wheel speed from the driven wheel speed, a difference between the simulated wheel speed and the driven wheel speed is calculated and compared with a predetermined threshold value, and the driven wheels W _RL , W
A change amount calculating means M3 for determining whether _RR is in a locked state or an unlocked state, a pseudo wheel speed correcting means M4 for correcting a pseudo wheel speed based on an output of the change amount calculating means M3, and a change amount calculating means M3 Selecting means M5 for outputting either the driven wheel speed or the simulated wheel speed as the vehicle speed based on the output of the vehicle, road surface friction coefficient estimating means M6 for estimating the road surface friction coefficient, and the threshold value and the predetermined value based on the road surface friction coefficient. And a threshold / predetermined value correcting means M7 for correcting the value.

The turning state determining means M1 is provided with a left driven wheel speed VWNL output from the left and right driven wheel speed detecting means 1 _RL and 1 _RR.
And the driven wheel speed V which is the average value of the right driven wheel speed VWNR.
VNHOS is calculated, and when the driven wheel speed VVNHOS is equal to or more than a predetermined value (for example, 60 km / h) and the lateral acceleration LG output by the lateral acceleration detecting means 4 is equal to or more than a predetermined value (for example, 0.5 G), or Wheel speed VVNHOS
Is greater than or equal to the predetermined value, and if the actual yaw rate Y output by the actual yaw rate / rotational vibration calculation means 33 is greater than or equal to a predetermined value (for example, 50 deg / s), it is determined that the vehicle is turning and the left driven wheel speed is determined. VWNL and right driven wheel speed VW
Higher one of NR is selected and the vehicle speed VV
Output as N.

One of the left driven wheel speed VWNL and the right driven wheel speed VWNR is the left and right driven wheel speed detecting means 1 _RL ,
1 _RR , when one of the failures results in a value below a predetermined value, the left driven wheel speed VWNL and the right driven wheel speed VWN
R, that is, the output signal of the driven wheel speed detecting means 1 _RL , 1 _RR on the non-failed side is output from the vehicle speed VV.
Select as N.

When the turning state determining means M1 determines that the vehicle is not in the predetermined turning state, the pseudo wheel speed calculating means M2, the change amount calculating means M3, the pseudo wheel speed correcting means M4, and the selecting means M5 determine whether the vehicle is in the turning state. Calculate the speed VVN. At this time, based on the road surface friction coefficient estimated by the road surface friction coefficient estimation unit M6, the reference value / predetermined value correction unit M7 corrects the threshold value and the predetermined value for obtaining the vehicle speed VVN.

Hereinafter, the above process will be described with reference to the block diagram of FIG. 4 and the flowcharts of FIGS.

In the flowchart of FIG. 5, first, after calculating the slip ratio SLIPR of the drive wheels W _FL and W _FR (step S1), the slip ratio SLIPR and the longitudinal acceleration FG are calculated.
Then, the road surface friction coefficient MUCON is estimated based on the lateral acceleration LG (step S2). Then, based on the estimated road surface friction coefficient MUCON, a threshold value MXFVL,
The MXFVBL and the predetermined values FVL and FVB are corrected (Step S3).

The contents of steps S1 to S3 will be described in detail with reference to the flowchart of FIG.

First, the slip ratio SL of the drive wheels W _FL , W _FR
The IPR is calculated based on the vehicle speed VVN and the driving wheel speed VWNHOS.
SLIPR = (VWNHOS−VVN) / VWNHOS, based on the equation (step S21). Note that the slip ratio S
It is also possible to calculate LIPR by SLIPR = (VWNHOS−VVN) / VVN.

The slip ratio SLIPR is compared with a threshold value SLIP1 on the positive side (the direction in which the driving wheels W _FL and W _FR rotate more than the driven wheels W _RL and W _RR ) (step S22, answer). Is NO and SLIPR ≦ SLIP1, the slip ratio SLIPR is further set to a preset negative threshold value (the direction in which the driving wheels W _FL and W _FR rotate less than the driven wheels W _RL and W _RR ). (Step S23), the answer is NO, and SLIPR ≧ SLIP2
, Ie, SLIP2 <SLIPR <SLIP1
In the case of, if the slip ratios SLIPR on the positive side and the negative side are relatively small and fall between the two threshold values SLIP1 and SLIP2, it is determined that the state before the traction control is started. Then, the process proceeds to step S24.

On the other hand, if the answer to step S22 is YES, S
If LIPR> SLIP1, or if the answer in step S23 is YES and SLIPR <SLIP2, then it is determined that the slip ratio SLIPR on the positive or negative side is relatively large and the traction control has been started. To step S25.

In step S24, the front and rear grip force FG
Read-only memory 22 based on the total grip force TG calculated as the vector sum of
The estimated road surface friction coefficient MUTG is retrieved from the table of Table 1 stored in the table.

[0040]

[Table 1]

As apparent from Table 1, the estimated road surface friction coefficient MUTG is [0] for each value of the total grip force TG,
Five levels of [1], [2], [3], and [4] are set, and the magnitude of the estimated road surface friction coefficient MUTG during turning of the vehicle is determined based on the total grip force TG. In step S24, the current estimated road surface friction coefficient MU
Only when an estimated road surface friction coefficient MUTG larger than TG is selected, the estimated road surface friction coefficient MUTG is updated.

When it is determined that the vehicle is running straight based on the output of the steering angle detecting means 3 (step S2).
6), Table 2 stored in the read-only memory 22
The estimated road surface friction coefficient MUFG is retrieved from the table of (2) based on the front-rear grip force FG (step S27).

[0043]

[Table 2]

As is clear from Table 2, the estimated road surface friction coefficient MUFG is [0] for each value of the front-rear grip force FG,
It is set in five stages of [1], [2], [3], and [4], and the magnitude of the estimated road surface friction coefficient MUFG during the straight traveling of the vehicle is determined based on the longitudinal grip force FG. In step S27, the estimated road surface friction coefficient MUFG is updated only when the estimated road surface friction coefficient MUFG larger than the current estimated road surface friction coefficient MUFG is selected.

On the other hand, in step S25, the estimated road surface friction coefficient MUTG is searched from the table of Table 1 based on the total grip force TG calculated as the vector sum of the longitudinal grip force FG and the lateral acceleration LG. The difference from step S24 is that the estimated road surface friction coefficient MUTG is updated according to the total grip force TG at that time.

When it is determined that the vehicle is running straight based on the output of the steering angle detecting means 3 (step S2).
8) The estimated road surface friction coefficient MUFG is retrieved from the table of Table 2 based on the front-rear grip force FG (step S29). At this time, the estimated road surface friction coefficient MUFG is calculated according to the current front-rear grip force FG. It differs from step S27 in that it is updated.

As is clear from comparison between Table 1 and Table 2, the estimated road surface friction coefficients MUTG and MUFG for the same grip force TG and FG are set so that MUFG is larger than MUTG. This is for giving priority to traction control at the time of turning and giving priority to traction control at the time of turning, and it is possible to arbitrarily set weights of the two in accordance with desired control characteristics.

In steps S30 to S32, the larger one of MUFG and MUTG is selected as the road surface friction coefficient MUCON, and the values of the road surface friction coefficient MUCON are "0", "1", "2". , "3",
Table 3 shows threshold values MXFVL and MXFVB according to “4”.
L and the correction values FVL and FVB are searched.

[0049]

[Table 3]

Subsequently, in the flowchart of FIG.
First, the previous value VWNB1 of the pseudo wheel speed VWNB calculated as the driven wheel speed VVNHOS, which is the average value of the left driven wheel speed VWNL and the right driven wheel speed VWNR, is compared with the current value of the driven wheel speed VVNHOS (step S4).
The answer to step S4 is YES, and the difference VWNB1-V
When VNHOS is positive and the driven wheel speed VVNHOS is decelerating, it is determined whether or not the difference VWNB1−VVNHOS is larger than the above-mentioned first threshold value MXFVL (step S5). The answer to step S5 is NO, and the difference VWNB1-VVNHOS is equal to the first threshold value MXFVL.
In the following cases, the driven wheel speed VVNHOS is set to the pseudo wheel speed VWNB (step S6), and the driven wheel speed VVNHOS is selected as the vehicle body speed VVN (step S7).

That is, the driven wheel speed VVNHOS
If the driven wheels W _RL , W _RR do not reach the locked state even if the vehicle speed V
Select as VN.

On the other hand, the answer to step S5 is YES, and the difference VWNB1-VVNHOS is equal to the first threshold value MX.
If it is larger than FVL, a value obtained by subtracting the first predetermined value FVL from the previous value VWNB1 of the pseudo wheel speed VWNB is set as a new pseudo wheel speed VWNB (step S8). If the difference VWNB1−VVNHOS continuously exceeds the first threshold value MXFVL for a predetermined number of times BTC (for example, 5 loops) (step S9), the pseudo wheel speed VWNB is selected as the vehicle speed VVN (step S10). .

That is, when the driven wheels W _RL and W _RR are locked by the braking and the driven wheel speed VVNHOS decreases rapidly, and the error between the driven wheel speed VVNHOS and the vehicle body speed VVN increases, the pseudo wheel speed VWNB is changed for each loop. To a first predetermined value F
When the state continues for a predetermined number of times BTC, it is determined that the driven wheels W _RL and W _RR are locked, and the driven wheel speed VVNHOS that no longer matches the actual vehicle speed VVN
, The pseudo wheel speed VWNB is selected as the vehicle speed VVN. The pseudo wheel speed VWNB decreases by a predetermined value FVL for each loop when the locked state of the driven wheels W _RL and W _RR continues, so that the first predetermined value FVL is set in advance according to the characteristics of the vehicle. By setting, the driven wheel W _RL ,
Even if W _RR is locked, the vehicle speed VVN can be accurately estimated.

The answer to step S9 is NO, and the difference VWNB1-VVNHOS is equal to the first threshold value MXFVL.
If the state larger than BTC does not continue for a predetermined number of times (1
Loop to 4 loops only), the driven wheel speed V
VNHOS is selected as the vehicle speed VVN (step S7). As a result, it is possible to reliably remove the influence of the case where the driven wheel speed VVNHOS temporarily fluctuates due to noise.

If the answer to step S4 is NO, the difference VWNB1-VVNHOS is negative and the driven wheel speed V
When the speed of VNHOS is increasing, the difference VWNB1-
It is determined whether or not the absolute value | VWNB1-VVNHOS | of VVNHOS is greater than the above-mentioned second threshold value MXFVBL (step S11). The answer to step S11 is NO, and the absolute value of the difference | VWNB1-VVNHOS
Is less than or equal to the second threshold value MXFVBL, the driven wheel speed VVNHOS is included in the pseudo wheel speed VWNB, and the driven wheel speed VVNHOS is set to the vehicle speed VV.
N is selected (steps S12 and S13).

On the other hand, if the answer to step S11 is YES and the absolute value of the difference | VWNB1-VVNHOS | is larger than the second threshold value MXFVBL, the previous value VWNB1 of the simulated wheel speed VWNB is set to the previously described value. 2 is added to the new pseudo wheel speed VWN.
B (step S14), and the absolute value of the difference | VWN
If B1-VVNHOS | continuously exceeds the second threshold value MXFVBL for a predetermined number of times BTC (for example, 5 loops) (step S15), the pseudo wheel speed VWNB is selected as the vehicle speed VVN (step S16).

More specifically, when the driven wheels W _RL and W _{RR that} have been locked by the braking are unlocked, the driven wheel speed VVNHOS increases rapidly, but the vehicle body speed VVN increases slowly. Therefore, the following wheel speed VV
If NHOS is selected as the vehicle speed VVN, a large error occurs. Therefore, the driven wheel speed VV
When the NHOS sharply increases and the error between the driven wheel speed VVNHOS and the vehicle speed VVN increases, the pseudo wheel speed VW
NB is incremented by a second predetermined value FVB for each loop, and if the state continues for a predetermined number of times BTC, it is determined that the driven wheels W _RL and W _RR have been unlocked, and the driven wheels no longer match the actual vehicle speed VVN. The pseudo wheel speed VWNB is selected as the vehicle speed VVN instead of the speed VVNHOS. The pseudo wheel speed VWNB increases by a predetermined value FVB for each loop when the driven wheels W _RL and W _RR are unlocked, so that the vehicle body speed VVN can be accurately estimated.

If the answer to step S11 is NO, it is determined that the increase in the driven wheel speed VVNHOS is not caused by the lock release, and the driven wheel speed VVNHOS is selected as the vehicle body speed VVN (step S12, S
13). If the answer to step S15 is NO, it is determined that the increase in the driven wheel speed VVNHOS is caused by noise, and the driven wheel speed VVNHOS is similarly selected as the vehicle body speed VVN (step S13). .

As shown in FIG. 8, even if the vehicle speed before control has a large error with respect to the actual vehicle speed due to the locking or unlocking of the driven wheels W _RL and W _RR , Thus, the estimated vehicle body speed VVN (the vehicle body speed after control) approaches the actual vehicle body speed, and traction control can be performed precisely. In addition, the threshold values MXFVL, MX taking into account the road surface friction coefficient MUCON
Since the FVBL and the correction values FVL and FVB are corrected, the vehicle speed VVN can be more accurately estimated.

Next, a second embodiment of the present invention will be described with reference to FIGS.
0 will be described.

In the first embodiment, the left driven wheel speed VWNL
And the driven wheel speed V which is the average value of the right driven wheel speed VWNR.
Although VNHOS is set as the initial value of the pseudo wheel speed VWNB, in the second embodiment, the left driven wheel speed VWNL and the right driven wheel speed VWNR are each set to the pseudo wheel speed VWNB, VWNB.
Using the initial value of WNLB, the locked state and the unlocked state of each of the left and right driven wheels W _RL and W _RR are determined to determine the vehicle speed VVN.

First, in steps S101 to S103, threshold values MXFVL, MX corresponding to the road surface friction coefficient MUCON
FVBL and correction values FVL and FVB are obtained. This process is the same as steps S1 to S3 in the flowchart of FIG.

The following steps S104R, S105R,
S106R, S108R, S111R, S112R, S
Reference numeral 114R relates to the right driven wheel W _RR , and corresponds to steps S4, S5, S6, S8, S in the flowchart of the first embodiment.
11, S12, and S14. That is, the right driven wheel speed VWNR is used instead of the driven wheel speed VVNHOS in the first embodiment, and the pseudo wheel speeds VWNB and VWN are used.
Instead of B1, pseudo wheel speeds VWNRB, VWNB1 are used.

Similarly, each of steps S104L and S105
L, S106L, S108L, S111L, S112
L, S114L not relate left driven wheels W _RL, step S4 of the flowchart of the first embodiment, S5, S6, S
8, S11, S12, and S14, the left driven wheel speed VWNL is used instead of the driven wheel speed VVNHOS in the first embodiment, and the pseudo wheel speeds VWNB and VWNB are used.
The pseudo wheel speeds VWNLB and VWNLB1 are used instead of 1.

If it is determined that at least one of the right driven wheel W _{RR and the} left driven wheel W _RL is in a locked state (YES in step S115), or the right driven wheel W _RR or the left driven wheel When it is determined that at least one of the W _RL is in the unlocked state (YES in step S116)
), The left and right pseudo wheel speeds VWNLB,
The average value of VWNRB is selected as the vehicle speed VVN (step S117).

When it is determined that neither the right driven wheel W _RR nor the left driven wheel W _RL is in the locked state or the unlocked state (steps S115 and S116 are both N).
O), the left and right driven wheel speeds VWL, VW at that time
The average value of R (that is, the driven wheel speed VVNHOS) is selected as the vehicle speed VVN (step S118).

As described above, according to the second embodiment, the vehicle body speed VVN can be accurately estimated even when only one of the left and right driven wheels W _RL and W _RR enters the locked state or the unlocked state. can do.

Although the embodiments of the present invention have been described in detail, various design changes can be made in the present invention without departing from the gist thereof.

For example, in the embodiment, a front wheel drive vehicle in which the rear wheels are driven wheels is illustrated, but the present invention can be applied to a rear wheel drive vehicle in which the front wheels are driven wheels.

[0070]

As described above, according to the first aspect of the present invention, the driven wheel speed changes abruptly when the driven wheel is locked or unlocked, and the driven wheel speed which has been selected as the vehicle body speed until then is changed. Even if the error between the running wheel speed and the actual vehicle speed increases, the vehicle speed can always be accurately estimated by selecting the pseudo wheel speed according to the actual vehicle speed instead of the driven wheel speed. Becomes Moreover, since the reference value and the predetermined value are corrected based on the road surface friction coefficient, the accuracy of estimating the vehicle speed is improved.

According to the second aspect of the present invention,
Even if the difference of the driven wheel speed with respect to the pseudo wheel speed due to the fluctuation of the driven wheel speed due to noise , that is, the amount of change temporarily exceeds the threshold value, the pseudo wheel speed is not selected as the vehicle body speed. The influence of noise on the estimation of the vehicle speed can be eliminated.

According to the third aspect of the present invention,
Only one of the left and right driven wheels is locked or unlocked.
Estimate vehicle speed accurately even when locked
Can be

According to the fourth aspect of the present invention,
Since the output of the engine is controlled according to the slip state of the drive wheel detected based on the estimated vehicle speed, excessive slip of the drive wheel can be suppressed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a vehicle including a traction control system.

FIG. 2 is a block diagram of a control system.

FIG. 3 is a block diagram showing a circuit configuration of an electronic control unit.

FIG. 4 is a block diagram of a vehicle speed calculating means;

FIG. 5 is a first partial diagram of a flowchart of vehicle body speed estimation.

FIG. 6 is a second partial diagram of a flowchart of vehicle body speed estimation.

FIG. 7 is a flowchart of a subroutine of steps S1 to S3.

FIG. 8 is a graph showing vehicle speed;

FIG. 9 is a first diagram of a flowchart of vehicle body speed estimation according to the second embodiment.

FIG. 10 is a second partial diagram of a flowchart of vehicle body speed estimation according to the second embodiment.

[Explanation of symbols]

M2 pseudo wheel speed calculating means M3 change amount calculating means M4 pseudo wheel speed correcting means M5 selecting means M6 road surface friction coefficient estimating means M7 threshold value / predetermined value correcting means BTC predetermined number of times FVB predetermined value FVL predetermined value MUCON road surface friction coefficient MXFVBL threshold value MXFVL Threshold VVN Vehicle speed VVNHOS Driven wheel speed VWNB Pseudo wheel speed VWNL Driven wheel speed VWNLB Pseudo wheel speed VWNR Driving wheel speed VWNRB Pseudo wheel speed W _FL drive wheel W _FR drive wheel 40 Engine output control means E Engine

────────────────────────────────────────────────── ⁷ Continued on the front page (51) Int.Cl. ⁷ Identification code FI F02D 45/00 314 F02D 45/00 314M (56) References JP-A-4-185567 (JP, A) JP-A-6-127364 (JP, A) JP-A-7-329756 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 29/02 311 B60K 28/16 B60T 8/58 F02D 41/04 F02D 45/00

Claims (4)

(57) [Claims] 1. A left driven wheel speed (VWNL) and a right driven wheel
The driven wheel speed (VVNH) which is the average value of the speed (VWNR)
The OS) and pseudo wheel speed (pseudo wheel speed calculating means for calculating as VWNB) (M2), the pseudo wheel speed (VW
NB) to the previous value (VWNB1) of the driven wheel speed ( V
VNHOS) and calculate the threshold value (MXFVL, M
XFVBL), and the difference is calculated by the change amount calculating means (M3).
XFVL, predetermined value to the pseudo wheel speed (V WNB) when it is determined to have exceeded the MXFVBL) (FVL, FV
B) by subtracting or adding the pseudo wheel speed ( V
WNB), a pseudo wheel speed correction means (M4) for correcting
The difference is the threshold value (MXFVL, MXFVBL) wherein in place of the follower wheel speed (V VNHOS) when it exceeds a vehicle speed pseudo wheel speed is corrected (V WNB) in the pseudo wheel speed correcting means (M4) (VVN) and a road friction coefficient estimating means (MCON) for estimating a road friction coefficient (MUCON) of a road on which the vehicle travels.
6) and the threshold value (MXFVL, MXFVBL) and a predetermined value (FVV) based on the road surface friction coefficient (MUCON).
L, FVB) and threshold value / predetermined value correction means (M
7) A vehicle speed estimating apparatus for a vehicle, comprising: 2. The method according to claim 1, wherein the selecting means (M5) determines whether or not the difference calculated by the change amount calculating means (M3) exceeds the threshold value (MXFVL, MXFVBL) continuously for a predetermined number of times (BTC). V VNHOS) to the vehicle speed (VV
N) and the difference is a predetermined number of times (BTC)
Continuously threshold (MXFVL, MXFVBL) if exceeded and selects the pseudo wheel speed corrected by the pseudo-wheel speed correcting means (M4) (V WNB) as vehicle speed (VVN) The vehicle body speed estimating device according to claim 1. 3. A pseudo-vehicle for a left driven wheel speed (VWNL).
Wheel speed (VWNLB) and right driven wheel speed (VWNLB)
NR) as the right pseudo wheel speed (VWNRB), and the previous value ( V2) of the left and right pseudo wheel speeds (VWNLB, VWNB).
WNLB1, left for VWNRB1), right follower wheel speed (VWNL, each respectively calculated by the threshold value the difference between the VWNR) and (MXFVL, MXFVBL) and change amount calculating means for comparing each (M3), the change amount calculation means According to (M3), the difference is a threshold value (MXFVL, MXF
VBL), the pseudo wheel speeds (VWNLB, VWNRB) are set to predetermined values (FVL, FVRB).
B) by subtracting or adding the pseudo wheel speed (V
WNLB, VWNRB) and at least one driven wheel speed (VWN).
L, VWNR) is the threshold value (MXFVL, MX)
Left in the case beyond the FVBL), right subordinate wheel speed (VWN
L, VWNR) instead of the average (VVNHOS)
Selection means (M5) for selecting the average of the right pseudo wheel speeds (VWNLB, VWNRB) as the vehicle speed (VVN)
And the road surface friction coefficient (MUCON) of the road on which the vehicle travels
Road friction coefficient estimating means (M6) for estimating the threshold value (MXFV) based on the road friction coefficient (MUCON).
L, MXFVBL) and a threshold value / predetermined value correcting means (M7) for correcting predetermined values (FVL, FVB). 4. A traction control device comprising the vehicle body speed estimation device according to claim 1, 2, or 3, wherein a drive wheel (W _FL ) detected based on the estimated vehicle body speed (VVN). , W _FR ), the engine output control means (40) for controlling the output of the engine (E) according to the slip state.
A traction control device comprising: