JP2669653B2 - Automotive slip control device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of an automobile slip control device for preventing slippage of drive wheels of a vehicle to improve running stability.

2. Description of the Related Art Conventionally, as a vehicle slip control device of this kind, for example, as disclosed in Japanese Patent Application Laid-Open No. 61-182434, the speed difference between a drive wheel and a driven wheel of a vehicle is determined by slipping the drive wheel. The engine output is feedback-controlled by controlling the opening degree of the throttle valve of the engine so that the slip amount of the drive wheel becomes the control target value.
It is known that the rotational speed of the drive wheels is adjusted to effectively prevent the slip and to improve the running stability of the vehicle.

(Problems to be Solved by the Invention) By the way, when driving a vehicle, it is preferable to increase the engine output and accelerate the vehicle in response to the driver's depression of an accelerator pedal, which gives a good driver's operational feeling. It is possible and preferable.

However, when the slip amount feedback control is performed as described above, the slip amount of the drive wheels is controlled to the control target value regardless of the depression operation of the accelerator pedal, and the rotational speed of the drive wheels is increased. Therefore, the driver feels that the vehicle speed does not increase even when the driver depresses the accelerator pedal, and the operation feeling is reduced.

The present invention has been made in view of such a point, and an object thereof is to directly react the movement of the vehicle in response to the depression operation of the accelerator pedal of the driver as much as possible even during the feedback control of the slip amount, and to perform the operation. It is to improve the feeling.

(Means for Solving the Problems) In order to achieve the above object, the present invention focuses on a situation in which the slip amount is less than the control target value even during feedback control. In this situation, the engine output is slightly increased. However, since the slip amount control is not hindered and the drive wheels are not slipped, the engine output is controlled to be slightly forcibly increased in response to the driver's depression of the accelerator pedal only in this situation.

That is, as shown in FIG. 1, the specific configuration of the present invention includes an output adjusting means 10 for adjusting the engine output, a slip detecting means 25 for detecting a slip of the drive wheels, and a detection by the slip detecting means 25. With the feedback control means 26 for feedback-controlling the output adjusting means 10 so that the slip amount to be the control target value, the depression detecting means 27 for detecting the depression time of the accelerator pedal 11, and the depression detecting means 27. The comparison means 29 for comparing the detected slip amount of the driving wheel when the accelerator pedal 11 is depressed with the allowable value less than the control target value, and the comparison result by the comparing means 29 shows that the slip amount is less than the allowable value. While controlling the output adjusting means 10 in preference to the feedback control means 26 so as to increase the engine output according to the depression of the pedal, When larger, it is assumed that a increase control unit 28 to continue the feedback control by the feedback control means 26.

(Operation) With the above-described configuration, in the present invention, during feedback control of the engine output, the slip amount of the drive wheels gradually converges to the control target value. Since there is some margin for slippage of the driving wheels, if the driver depresses the accelerator pedal 11 in this situation, even if the engine output is forcibly controlled to increase by the increasing control means 28, the driving wheel The vehicle can be accelerated according to the depression of the accelerator pedal without causing a slip.

(Effect of the Invention) As described above, according to the vehicle slip control device of the present invention, when the slip amount of the drive wheel is feedback-controlled to the control target value, the engine output is controlled with respect to the occurrence of the slip of the drive wheel. When there is a margin to increase, the engine output is forcibly increased slightly in response to the driver's depression of the accelerator pedal, so the vehicle is directly controlled in response to the driver's acceleration request without causing slippage of the drive wheels. The reaction can be accelerated, and the operational feeling of the driver can be improved.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS.

FIG. 2 shows an overall schematic configuration of a vehicle slip control device according to the present invention, wherein 1 is an engine, and 2 is, for example, a forward 4
In the automatic transmission having one gear and one reverse gear, the engine power changed by the automatic transmission 2 is transmitted to the left and right via a propulsion shaft 3, a differential device 4 and a rear axle 5 arranged behind the transmission 2. Rear wheel
6 and 6, the rear wheel 6 is used as a drive wheel, and the left and right front wheels 7, 7
Is configured as a driven wheel.

Further, a throttle valve 10 as an output adjusting means for adjusting an engine output by controlling an intake air amount is disposed in an intake passage 1a of the engine 1. The throttle valve 10
Is a throttle actuator that has no mechanical interlocking relationship with the accelerator pedal 11 and is composed of a step motor, etc.
The opening is electrically controlled by 12.

Further, near the front, rear, left and right wheels 6, 7, wheel speed sensors 13, 13,... For detecting the rotation speed of the wheels are provided, respectively, and an opening sensor 14, for detecting the opening of the accelerator pedal 11, Steering angle sensor 15, which detects the steering angle,
Brake sensor 16, which detects when the brake pedal is depressed,
A range sensor 17 that detects the range of the automatic transmission 2 is provided. Thus, the detection signals of the above sensors 13 to 17 are input to the controller 20 having a CPU or the like,
The controller 20 controls the engine output by controlling the opening of the throttle valve 10 so as to suppress and prevent the rear wheels (drive wheels) 6 from slipping.

Next, the slip control by the controller 20 will be described with reference to the control flows of FIGS.

First, as explained from the main flow of FIG. 3, after initializing the system in step S _M1 , step S _M2
The throttle valve 10 according to the amount of depression of the accelerator pedal 11
The target opening NTAG of is calculated, and the slip control of the drive wheels 6 is performed based on the slip control flow of FIG. 5 in step S _M3 . Basically, during slip control, the throttle valve 10 is opened to the control opening STAG. During normal control that does not require slip control, the target opening NTAG according to the pedal depression amount
The control is repeated to return to step S _M2 .

Next, the control flow of FIG. 4 will be described. The control flow is started by interrupting the main flow of FIG. 3 at predetermined time intervals, and at step S _I1 , the wheel speed, accelerator pedal opening, and steering angle are set. After inputting various data such as, etc. and performing signal processing, in step S _I2 , decrement processing etc. is performed for various control timers, and in step S _I3 the opening of the throttle valve 10 is actually set to the target opening NTAG or control opening. Control by STAG and finish.

Next, the slip control flow of FIG. 5 will be described. First, a Y / N of the slip control is determined in the ON / OFF state of the traction switch driver selects in step S _1, ON
When requesting a slip control state, performing slip control of the driving wheels (rear wheels) 6 at step S ₂ and subsequent.

And Thus, to determine the coefficient of friction of the extent and the road surface slip (hereinafter referred to as mu) in step S ₂ and subsequent. First, step S ₂
At rear wheel speed (drive wheel speed) WR and front wheel speed (driven wheel speed)
Compare with FW. Here, the driving wheel speed WR uses the larger speed of the left and right rear wheels, and the driven wheel speed FW uses the average of the rotational speeds of the left and right wheels. And Thus, when WR-FW is large large spin, to determine the value of (SPIN = 0 when a large spin) spin flag SPIN in step S _3, if the SPIN ≠ 0 it is determined that the time of a large spin-generating In step S ₄ , the spin flag SPIN = 0 is set, in step S ₅ , the road surface μ determination timer GTIM is initialized to a predetermined value (for example, GTIM = 33), and the road surface μ determination end flag GCF (μ determination end initial set GGF = FF) to GGF = 0, the addition to proceed step S ₁₁ the current follower wheel speed FW as the previous follower wheel speed FWOLD.

On the other hand, if the speed difference between the front and rear wheels in step S ₂ (WR-FW) is not large, further spin flag at step S ₆ SP
To determine the value of the IN, only when a large spin SPIN = 0, a predetermined value a timer RECTM for a predetermined time measured in step S ₇ (e.g. R
Initially set to ECTM = 22). Then, SPIN = 100 spin flag SPIN in step S ₉ to determine whether the medium speed difference between the front and rear wheels (WR-FW) is at step S _8, when moderate
To, if the speed difference (WR-FW) is smaller S at Step S ₁₀
Set PIN = 255 respectively.

Thereafter, and determining the mu of the road surface in the step S ₁₁ and subsequent, first only for mu determination end flag GGF = 0 in step S ₁₁ (mu pre-determination), a timer for mu determination of the road surface in the step S ₁₂ GTIM The value of is discriminated and GTIM =
When a predetermined time has elapsed became 0, the follower wheel speed at this time of the driven wheel speed FW and the previous Step S ₁₃ (large spin time of occurrence)
Grasping the acceleration GG (= FW-FWOLD) of the driven wheel from the difference with FWOLD, and based on the current driven wheel speed FW and the acceleration GG of the driven wheel in step S ₁₄ , the map of the road surface from the map shown in the same step is used. Understand μ. Here, the same driven wheel speed on the map
In FW, the higher the driven wheel acceleration GG, the higher the road surface μ, so
In the region MU = 1, μ is low, in the region MU = 2, μ is medium,
In the region MU = 3, μ is high. Then, after determining the μ of the road surface is, GGF a μ determination end flag GGF in step S ₁₅ = FF
Is set to (mu determination end), and to move to the subsequent slip control step S _16.

In the slip control in step S ₁₆ and subsequent, first determine the presence or absence of depression of the accelerator pedal 11 in step S _16, and by performing a depression (when ON) unless slip control, the slip control flag SPINC in step S ₁₇ ( determine the value in a slip control 0), at the time of the slip control starting of SPINC ≠ 0, further to determine the value of the spin flag sPIN in step S _18, the accelerator and throttle valve opening in the spin state of convergence sPIN = 255 in order to set the opening degree value according to the degree of depression of the pedal, the process immediately proceeds to step S _32.

On the other hand, in the case of SPIN ≠ 255 in step S _18, after setting the slip control flag SPINC to SPINC = 0 in step S _19, the rotational speed of the front and rear wheels in the feedback control of the rotational speed of the drive wheels in step S ₂₀ In order to make the difference a predetermined value ΔN according to μ on the road surface and the depression amount of the access pedal 11, the target rotation speed MOKU of the drive wheels is set in advance to MOKU = FW + ΔN. Here, the basic value of the rotational speed difference (target slip amount of the rear wheels) ΔN between the front and rear wheels is, for example, 2 km / h in the area MU = 1 (low μ road) and 4 km in the area MU = 2 (middle μ road). / h
In the area MU = 3 (high μ road), each is set to 6km / h, and these basic values are multiplied and corrected by the correction coefficient kacc according to the amount of depression of the accelerator pedal 11, and the target slip amount of the rear wheels (slip of the rear wheels) Control target value of ΔN. This correction coefficient kacc
As shown in FIG. 7, a predetermined value (for example, 0.5 is maintained in a region below the predetermined depression amount of the accelerator pedal 11, and the value gradually increases in accordance with an increase in the depression amount of the accelerator pedal 11 in a region exceeding the predetermined depression amount. The characteristic is set to 1.0 at the full depression amount, and when the depression amount of the accelerator pedal 11 is increased, the target slip amount ΔN of the rear wheels is gradually increased, and the target rotation speed of the rear wheels (driving wheels) is also high. Become.

Thereafter, each spin flag SP in step S ₂₁ and S ₂₂
To determine the value and the value of the measuring timer RECTM after large spin convergence IN, at the time of a large spin generation of SPIN = 0, feed forward control the opening degree of the throttle valve 10 to a smaller opening value proceeds to step S ₂₃ ( The target forward control opening value STAG corresponding to the rotation speed FW of the driven wheel is determined based on the map shown in FIG. This control opening value STAG is set according to the estimated μ of the road surface,
The lower the road surface μ, the smaller the opening value.

Further, after the large spin generation described above, when the spin somewhat fit the SPIN ≠ 0 in step S _21, the timer RECTM ≠
Before the predetermined time of 0 has elapsed, the field control is performed so that the forward control opening value STAG set to the small opening value as described above is restored in a short time (see FIG. 6B), and step S ₂₄ Then, the target forward return control value STAG corresponding to the rotational speed FW of the driven wheels is obtained based on the map shown in the same step. This return control value STAG is set in accordance with the estimated road surface μ in the same manner as described above.

If SPIN = 0 and timer RECTM = 0,
Feedback control so that the target rotation speed MOKU of the driving wheel calculated in step S ₂₅ in the step S ₂₀ (for example, PI
-PD method) to set the target opening value STAG.

After that, in response to the depression of the accelerator pedal 11 or the release side operation, the vehicle is directly accelerated or decelerated within an allowable range according to the depression / release operation.
Target opening STAG feedback control based on the target throttle valve opening NTAG according to the accelerator pedal depression amount at S ₂₆
According to the following equation, when the accelerator pedal depression amount is increased, it is corrected to the opening degree increasing side, and when the depression amount is decreasing, it is corrected to the opening degree decreasing side.

STAG = (0.3 × NTAG + 0.7 × STAG) / 2 Then, if the accelerator pedal 11 is open (opening operation halfway or) determines whether at step S _27, are open YE
In the case of S, the slip ratio of the driving wheels 6 (drive wheel rotation speed / the driven wheel rotational speed) to determine whether the time of excessive or above the set value in step S _28, when not excessive, i.e. of the drive wheel 6 slip amount is the target slip amount when the allowable value or less than the allowable value (control target value) .DELTA.N the control target opening degree correction target opening at the time of accelerator pedal depression determined in step S ₂₆ in step S ₂₉ STAG.

On the other hand, if not the accelerator pedal 11 is depressed in step S _27, in particular at the time of reduction of the amount of depression of the accelerator pedal 11 immediately proceeds to step S ₂₉ to set the correction target opening value as a control target opening STAG .

Thereafter, the target opening S of the slip control in step S ₃₀
TAG and target opening NTAG according to accelerator pedal depression amount
Comparing the door, if the STAG ≦ Ntag are the time of the slip control required, and controlling the opening value TAGET to be actually controlled in step S ₃₁ as the target opening degree STAG determined by the slip control, finish.

On the other hand, in the case of STAG> Ntag in step S _30, in order to control the degree of opening in accordance with the usual accelerator pedal, a slip control flag SPINC in step S ₃₂ in SPINC = 255 (required when slip control) With setting, step S ₃₃
In setting the mu determination end flag GGF road to GGF = FF (mu determination end) to the opening value TAG to be actually controlled in step S ₃₄
ET is controlled as the target opening degree NTAG according to the accelerator pedal depression amount, and the processing ends.

Therefore, in step S _2, S ₈ of the control flow of the four wheel speed sensors 13, 13 and Figure 5, it constitutes a slip detection means 25 to detect the slippage of the driving wheels 6. Further, in step S _20, S _25, the slip amount of the drive wheel 6 which is detected by the slip detecting means 25, as shown in FIG. 6 (c), the control target value (driving wheel (rear wheel) 6 and the slave A feedback control means 26 for performing feedback control of the throttle valve 10 so as to make the rotational speed difference (WR-FW) ΔN between the driving wheel (front wheel) 7 and the driving wheel 7 is constituted.

Further, in step S ₂₇ of the control flow, together with constitute a depression detecting means 27 for detecting the time of depression of the accelerator pedal 11, the step S _28, when depression of the accelerator pedal 11 detected by the depression detection unit 27 The comparison means 29 is configured to compare the slip ratio of the drive wheel 6 with the allowable value of less than the set value, that is, the slip amount of the drive wheel 6 less than the target slip amount ΔN. Further, in step S _29, the result of comparison by the comparing means 29, when the slip amount is less than the allowable value, increases correcting the correction target opening value STAG to the target opening value NTAG according to the accelerator pedal depression amount And the feedback control means increases the output of the engine 1 in accordance with the depression of the accelerator pedal 11.
The increase control means 28 is configured to control the opening of the throttle valve 10 prior to the control of the control valve 26 and to continue the feedback control by the feedback control means 26 when the opening degree is larger than the permissible value.

Therefore, in the above embodiment, the throttle valve is adjusted in accordance with the slip amount of the WR of the driving wheels (rotation speed difference (WR-FW)).
The opening control of 10 is appropriately switched between feedback control and feedforward control.

Now, when a large slip occurs, the rotational speed difference between both wheels (GW
-FW) is a large situation as shown in FIG. 8, but at this time, the opening of the throttle valve 10 is first subjected to feedforward control as shown in FIG. 9, and the target forward control opening ST.
After the speed is rapidly reduced to AG, the feedforward control is performed again, and the quick return control to the target forward return control value STAG is performed. Therefore, the rotation speed of the drive wheel 6 immediately decreases and the spin converges. The target rotation speed in the feedback control that becomes faster
It quickly returns to the vicinity of MOKU, and its return responsiveness is improved.

Thereafter, since the opening degree of the throttle valve 10 is feedback-controlled by the feedback control means 26, the rotation speed GW of the drive wheel 6 converges favorably to the target rotation speed MOKU, and the subsequent slip is effectively prevented. It will be.

In this case, when the accelerator pedal 11 is depressed as shown in FIG. 10 during the feedback control of the slip amount of the drive wheels 6, the target value slip amount ΔN of the drive wheels 6 also increases in accordance with the increase in the depression amount. The target rotation speed MOKU of the drive wheels 6 also increases (step in FIG. 5).
S _20). Thus, the target opening value STAG of the throttle valve 10 in the feedback control is increased (step S _25), the target opening value of the slip control on the basis of the target opening value NTAG of the target opening value STAG and normal control STAG is corrected to increase side (step S _26, S _29), only the state slip ratio of the driving wheels 6 having a margin on the slip occurs at less than the set value, the throttle valve opening is the correction target opening value STAG , The engine output increases, the rotation speed of the drive wheels 6 increases, and the vehicle accelerates accordingly. Therefore, the vehicle can be directly reacted and accelerated in response to the driver's depressing operation of the accelerator pedal 11 without causing the driving wheel 6 to slip, and the operational feeling of the driver can be improved.

In the above embodiment, the target slip amount ΔN of the drive wheel 6 is
7 was variably controlled according to the amount of depression of the accelerator pedal 11 based on the characteristic diagram of FIG. 7, but instead of the characteristic diagram of FIG. 7, the slip amount ΔN of the drive wheel 6 was changed by the rate of change of the accelerator pedal opening. You may correct. Further, it goes without saying that the same can be applied to the case where the fixed control is performed regardless of the accelerator pedal depression amount. FIG. 11 shows how the rotation speed of the drive wheel 6 increases in this case.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the configuration of the present invention. 2 to 10 show an embodiment of the present invention, FIG. 2 is an overall schematic diagram, FIGS. 3 to 5 are flow charts showing a drive wheel slip control by a controller, and FIG. FIG. 7 is an explanatory diagram of engine output reduction and return control by forward control, and engine output control by feedback control. FIG. 7 is a diagram showing a correction coefficient characteristic of a target slip amount of a drive wheel with respect to an accelerator pedal depression amount, and FIG. FIG. 9 is an explanatory diagram showing how the rotational speeds of the driving wheels and the driven wheels change during a large slip, FIG. 9 is an operation explanatory diagram showing how the throttle valve opening changes when a large slip occurs, and FIG. FIG. 7 is an explanatory diagram showing how the rotational speeds of the drive wheels and the driven wheels change with the depression of the accelerator pedal during the subsequent feedback control. No.
FIG. 11 is a view corresponding to FIG. 10 when the target slip amount of the driving wheels does not change according to the accelerator pedal depression amount. 1 ... engine, 6 ... rear wheel (drive wheel), 7 ... front wheel (driven wheel), 10 ... throttle valve (output adjustment means), 13
...... Wheel speed sensor, 20 ...... Controller, 25 ...... Slip detection means, 26 ...... Feedback control means, 27 ......
Depressing detection means, 28 ... increase control means, 29 ... comparison means.

Claims (1)

(57) [Claims] An output adjusting means for adjusting an engine output; a slip detecting means for detecting a slip of a driving wheel; and a feedback to the output adjusting means so that a slip amount detected by the slip detecting means becomes a control target value. In addition to the feedback control means for controlling, the depression detecting means for detecting the depression of the accelerator pedal, and the slip amount of the drive wheel at the depression of the accelerator pedal detected by the depression detecting means are allowed values below the control target value. And comparing the output adjustment means with priority to the feedback control means so as to increase the engine output in response to depression of the accelerator pedal when the slip amount is equal to or less than the allowable value. On the other hand, when the control value is larger than the allowable value, the feedback control means is used. Vehicle slip control system being characterized in that a increase control means for continuing the fed back control.