JPH08165940A - Acceleration slip control device - Google Patents

Abstract

(57) [Abstract] [Purpose] In acceleration slip control by engine output control, improve acceleration performance when starting on an extremely low μ road. When a road surface state detection unit detects a (very) low friction road surface, a control amount of engine output at the time of acceleration slip detection based on a road surface that is not a (very) low friction road surface is oscillated in a predetermined cycle. At this time, a predetermined increase correction amount and a predetermined decrease correction amount are added to the control amount of the engine output in a predetermined cycle. Alternatively, the control amount of the engine output is set to almost zero in a predetermined cycle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects a slip of a drive wheel that occurs when the vehicle starts or accelerates, controls the engine output based on the slip detection, and suppresses the slip of the drive wheel. The present invention relates to an acceleration slip control device.

[0002]

2. Description of the Related Art Conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open No. 3-74227, acceleration slip control for controlling engine output by performing throttle control based on a slip state of drive wheels at vehicle start or acceleration The system is known.

In an acceleration slip control system that executes engine output control by throttle control or the like, the relationship between the front-rear and lateral forces that can be exerted by the tire is the coefficient of friction μ between the tire and the road surface and the slip ratio S during braking / driving. Μ-
Assuming that it is based on the S characteristic, the slip rate (target slip rate, usually set to about 3%) that can ensure both vehicle stability and efficient transmission of the driving force to the road surface, is achieved.
Are controlled to become.

For example, as shown in FIG. 12, in order to obtain this constant target slip ratio, the throttle opening is obtained and controlled by feedback calculation using the difference in speed between the driving wheel and the driven wheel as a deviation.

This target slip ratio is the coefficient of road friction μ
Also, because the optimum value changes depending on the state of the vehicle, for example, when the vehicle is turning, the friction coefficient μ of the road surface (hereinafter simply referred to as μ
Is called) or a method of discriminating the vehicle state and changing the target slip ratio. Also, stability does not become a problem at low speeds such as when starting, and driving force is required.
Inventions have been devised to increase the target slip ratio to a value higher than usual. The means for controlling the target slip ratio is generally a means for reducing the engine output due to a throttle valve, ignition retard, fuel cut, ignition cut, or the like.

[0006]

In recent years, an extremely low μ road, which is a so-called mirror road surface, has come to appear frequently, especially in cold regions, reflecting the social situation of abolishing spiked tires and popularization of studless tires. It was In general, the mirror road surface is often formed on a part of the entire road surface (a portion where many vehicles pass), but in some cases, almost the entire road surface may be a mirror road surface.

However, the above-mentioned conventional acceleration slip control by the engine output control has a problem that it may be difficult to cope with such an extremely low μ road as represented by the mirror road surface.

That is, for example, when the road surface μ is not uniform on the entire road surface, and especially when μ is different on the left and right sides, only one of the driving wheels on the extremely low μ side is likely to slip, but engine output control is performed on the average of the left and right wheels. Since the control is performed, independent control of the left and right wheels cannot be performed, the driving force on the high μ side cannot be effectively used, and acceleration failure may occur.

In such a so-called "spanning start" in which the road surfaces μ of the left and right wheels are different on such an extremely low μ road, the LSD (Limited Slip Differential) effect due to internal friction of the differential accelerates the vehicle to make a large slide. However, according to the conventional concept of acceleration slip control, the control of "sliding large" is not performed.

Further, as a practical problem, in the conventional acceleration slip control, the target slip ratio is set so as to obtain good performance for a wide range of road surface μ even on both wheels low μ road, and therefore it changes every moment. There is a problem that the optimum slip ratio does not correspond to the actual road surface μ, the road surface μ determination has a problem in calculation time and accuracy, and the effect is small.

Further, as a new problem of a different dimension from these problems, it is necessary to start on a road surface where the entire road surface is a mirror road surface (extremely low μ road) and the road surface is slightly inclined. In this case, slip may occur even in the creep state where the throttle opening is "fully closed".
(Because the engine output cannot be further reduced), it may be difficult to cope with the conventional acceleration slip control.

In this case, a knowledgeable driver can start slipping on the extremely low μ road while suppressing slip due to creep by both depressing the accelerator and the brake. In particular, a driver who recognizes that the vehicle has an acceleration slip control device does not even step on the accelerator when starting and does not apply the brakes even if he does not step on it. However, there was a case where it was not possible to suppress the slip at the time of starting acceleration and it was not possible to start satisfactorily.

Further, particularly under such a condition, when the driver steps on the accelerator, the throttle is fully closed (despite the step on the accelerator) and the engine speed does not rise, and There was also the problem of giving the driver a feeling of discomfort because the vehicle was in an unusually quiet and stopped state where it did not start (due to slip).

The present invention has been made in order to solve the above-mentioned conventional problems, and by radically revising the conventional concept of "accelerating slip control" of "not slipping more than a predetermined value", particularly in the case of a mirror road surface. It is an object of the present invention to provide an acceleration slip control device capable of greatly improving the acceleration performance when starting on a very low μ road.

[0015]

SUMMARY OF THE INVENTION The present invention, as shown in FIG. 1, shows an acceleration slip detecting means for detecting the occurrence of an acceleration slip on a drive wheel, and an engine output control at the time of detecting the acceleration slip. In the acceleration slip control device including the means, a road surface condition detecting means for detecting whether or not the traveling road surface is a low friction road surface, and a low friction when the road surface condition detecting means detects a low friction road surface. The object is achieved by providing a means for vibrating the control amount of the engine output at the time of detecting the acceleration slip based on a road surface which is not a road surface in a predetermined cycle.

The present invention also provides a control amount correction means for vibrating the control amount of the engine output at a predetermined cycle, and a control amount correction means for adding a predetermined increase correction amount and a predetermined decrease correction amount to the engine output control amount at a predetermined period. By doing so, the above-mentioned object is similarly achieved.

The present invention also has the same object as above, wherein the means for vibrating the control amount of the engine output in a predetermined cycle is a control amount correcting means for making the control amount of the engine output substantially zero in a predetermined cycle. It has been achieved.

[0018]

According to the present invention, when the occurrence of acceleration slip is detected by the acceleration slip detecting means and the traveling road surface is detected as the low friction road surface by the road surface state detecting means, the above-mentioned method is based on the road surface which is not the low friction road surface. When the acceleration slip is detected, the control amount of the engine output is oscillated in a predetermined cycle, and the engine output is varied, so that a large slip and a grip are repeated on the drive wheels to generate rotational vibration. As a result, even in the case of an irregular road surface μ, it is possible to increase the chances of obtaining the driving force so that the maximum driving force can be obtained somewhere, and it is possible to improve the acceleration at the time of starting.

Further, even when one wheel slips, rotational vibration can be generated in that wheel to obtain the LSD effect and improve the acceleration performance.

When the acceleration slip and the low friction road surface are detected, if the control amount of the engine output is vibrated by adding a predetermined increase correction amount and a predetermined decrease correction amount in a predetermined cycle, the vibration is performed. Therefore, the normal control can be reflected and it can be adapted to acceleration or stability.

Further, when acceleration slip and low friction road surface are detected, when the engine output control amount is made to oscillate by making it substantially zero in a predetermined cycle, especially when the vehicle is started on all mirror road surfaces as described above. Even when the throttle is fully closed, slippage occurs, and even if the conventional control becomes impossible to control, it is possible to control the drive wheels to slip vibrantly and ensure acceleration and stability. be able to.

[0022]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 2 is a schematic configuration diagram of a vehicle equipped with the acceleration slip control device of the present invention.

In FIG. 2, reference numerals 10 and 12 denote left and right front wheels as driven wheels, and 14 and 16 denote left and right rear wheels as drive wheels. The output torque of the engine 18 is applied to the left and right rear wheels 14 and 16 by the transmission 20, the propeller shaft 22, the differential device 24, and the left and right drive axles 2.
It is transmitted via 6, 28. The engine 18 sucks intake air from the intake passage 30 and the surge tank 32 and is supplied with fuel from the fuel injection valve 34. The intake passage 30 is provided with a main throttle valve 36 for controlling the intake air amount. The main throttle valve 36 is connected to an accelerator pedal 38 and rotates in response to depression of the accelerator pedal 38.

The fuel injection valve 34 has an engine control unit 40.
The valve opening timing and the valve opening time are controlled by the control signal from, and fuel is injected and supplied to the engine 18 in an amount corresponding to the valve opening time. The fuel injection amount control by the engine control device 40 is basically performed according to the intake air amount or the intake air amount per stroke determined by the intake pipe pressure and the engine speed.

Main throttle valve 3 of intake passage 30
Sub-throttle valve 4 on the upstream side of the intake flow from 6
2 are provided. The sub-throttle valve 42 is driven to open and close by a step motor 44, and the step motor 44 controls the opening degree of the sub-throttle valve 42 according to a control signal from an electronic control unit 46 for acceleration slip control.

The electronic control unit 46 includes a general microcomputer and has drive wheel speed sensors 48 and 49.
Is taken as the driving wheel speed, the left and right driven wheel speed sensors 50, 52 take the left and right front wheels 10, 12 as the left and right driven wheel speeds, the gear shift position information is taken from the transmission 20, Information regarding the opening of the main throttle valve 36 is fetched from the opening sensor 54, information regarding the rotational speed of the engine 18 calculated by the engine control device 40 is fetched, and it is determined whether or not an acceleration slip has occurred in accordance with the information. When an acceleration slip occurs, a control signal for opening and closing the sub-throttle valve 42 to a predetermined opening suitable for acceleration slip control is output to the step motor 44.

Next, the extremely low μ road control which is repeatedly executed by the electronic control unit 46 every predetermined time will be described with reference to the drawings starting from FIG. This is a process for calculating the control amount for the opening / closing control of the sub-throttle valve 42 (or for calculating the fuel injection amount in the engine control device), and the processes shown in each of the figures after FIG. It is executed after the control is started.

First, FIG. 3 shows the control in the first embodiment. In the first embodiment, the extremely low μ road is judged from the vehicle body acceleration and the extremely low μ road control is executed.

When the flow of FIG. 3 starts, first, at step 100, the vehicle speed V _T0 at the start of control is 3 km.
/ H or less is determined. This is because if the vehicle starts moving at the start of control, acceleration failure is unlikely to occur. That is, V _T0 is 3 km / h as determined in step 100.
When it exceeds the above, it is determined that the extremely low μ road control is not necessary, and the routine proceeds to step 170, where the normal acceleration slip control is executed.

In step 110, the vehicle speed _V'T0 at the start of control is stored as _V'T0 (0), and the next step 1
If it is determined in step 20 that one second has elapsed, in step 130, the vehicle speed _V'T0 after one second is set to V '.
_It is stored as _T0 (1).

Next, the vehicle speed increases for one second from the control start in step _{140 V 'T0 (1) -V} ' is calculated to _T0 (0), which determines whether 2km / h or more. That is, in steps 110 to 140, the vehicle body acceleration is calculated,
Road surface μ is estimated (very low μ road detection). Step 14
If the increase in vehicle speed is 2 km / h or more as determined by 0, it is determined that the road is not an extremely low μ, and the routine proceeds to step 170. On the other hand, if the speed is less than 2 km / h, it is determined that the road is an extremely low μ, and the process proceeds to the next step 150.

In step 150, the normal acceleration slip control is switched to the extremely low μ road control, and the extremely low μ road control is executed. In extremely low μ road control, by adding an increase correction amount and a decrease correction amount to the target throttle opening,
The throttle valve is opened and closed in a predetermined cycle to vibrate the engine output. The extremely low μ road control will be described later in detail.

Next, at step 160, it is determined whether or not the vehicle speed has increased to some extent (here, whether or not the vehicle speed is 15 km / h).
If it does not rise, the process returns to step 150 to continue executing the extremely low μ road control, and when it rises, step 17
The process proceeds to 0 and returns to the normal acceleration slip control.

Next, the second embodiment will be described.

The control of the second embodiment is shown in the flowchart of FIG.

The step 200 in FIG. 4 is the same as the step 100 in the first embodiment.
As a condition for entering the road control, it is determined whether or not the target opening degree of the throttle at the start of control is a low opening degree (here, 10 deg). This is because if the target opening at the start of control is obtained from a one-dimensional map based on the engine speed, the lower the road μ, the lower the engine speed at the start of control and the smaller the target opening. is there.

Further, as a more accurate method, after a lapse of time from the start of control (for example, 1 second), the throttle opening at this time is preliminarily based on the engine output that can be exhibited at μ ≦ 0.1 or less. There is also a method of comparing with a one-dimensional map based on the set rotation speed.

If the result of determination in step 210 is that the opening is not low, the routine proceeds to step 240, where normal acceleration slip control is carried out, and if it is small, the routine proceeds to step 220 where extremely low μ road control is carried out.

At the next step 230, it is determined whether the vehicle speed V _T0 has increased (here, 15 km / h or more) and the vehicle has started.
Alternatively, it is determined whether or not the throttle opening has a certain opening (here, 10 deg or more), the vehicle is obviously moving, and the throttle has a closing margin. As a result of this determination, V _T0 ≧ 15 km / h or throttle opening> 10 de
If g, it is determined that the extremely low μ road control is no longer necessary, and the routine proceeds to step 240, where normal acceleration slip control is executed, and if not so, the routine returns to step 220 and the extremely low μ road control is repeated.

Next, a third embodiment will be described. This is to judge an extremely low μ road by using the stored value of the road surface μ calculated by the road surface μ estimation process proposed by the present inventor in Japanese Patent Laid-Open No. 5-86921.

The processing of the third embodiment is shown in the flowchart of FIG.

Step 300 of FIG. 5 is the same as step 100 of the first embodiment. At the next step 310, it is determined whether or not the road surface μ memory value is a low μ road. If the stored value corresponds to the extremely low μ road, the routine proceeds to step 320, where the extremely low μ road control is executed, and if not, the routine proceeds to step 340 where the normal acceleration slip control is executed. Note that step 330 is similar to step 160 of the first embodiment.

Next, a fourth embodiment will be described.

FIG. 6 shows the processing of the fourth embodiment. In the fourth embodiment, the extremely low μ road control is not performed after the low μ road is detected, but the extremely low μ road control is executed at the start of the control. When a high μ road is detected by the road surface μ stored value as described in the third embodiment, the normal acceleration slip control is switched to an extremely low μ.
It aims to eliminate the delay in the execution of road control.

In FIG. 6, step 400 is the same as step 100 of the first embodiment. In step 410,
The presence or absence of high μ road judgment is judged. If there is no high μ road judgment, the process proceeds to the next step 420, and the extremely low μ road control is continued to
If there is a road determination, the routine proceeds to step 440, where normal acceleration slip control is performed. Step 430 is the same as step 160 of the first embodiment.

Finally, the extremely low μ road control for vibrating the engine output in a predetermined cycle will be described.

As a concrete structure for realizing this, various structures can be considered as shown in FIG. 7, for example.

In FIG. 7A, the acceleration slip control means M
As in the conventional case, 1 determines the control amount of the engine output based on the driving wheel speed and the vehicle body speed so that the driving wheel slip ratio becomes a predetermined target slip ratio. Further, the target opening degree calculation means M2
A target opening degree of the throttle is calculated so as to obtain the control amount calculated by the acceleration slip control means M1. Drive means M3
Drives the throttle valve M5 provided in the intake passage M4 of the engine EG by an amount based on the target opening degree. The extremely low μ road detecting means M6 detects whether or not the road is an extremely low μ road from the driven wheel acceleration or the like by a known method, and the target opening correction means M7 performs the original control of the target opening calculation means M2. A correction amount is given to the target opening, and the corrected target opening is sent to the driving means M. As a result, the throttle is driven and the engine output is vibrated in a predetermined cycle.

Further, FIG. 7B shows the fuel cut updating means M8.
FIG. 7 (c) shows an example in which a vibration system for engine output control by fuel cut is provided in addition to a conventional acceleration slip control system by throttle control, which is provided with an engine control means M9.
Shows an example of a system that performs acceleration slip control including vibration in a diesel engine only by controlling fuel.

FIG. 8 is an example of a flow chart showing the first method of controlling the extremely low μ road.

In step 500, the throttle target opening calculated in accordance with the acceleration slip calculated in the normal acceleration slip control is calculated, and this value is calculated as TRC (m).
Memorize as. Even when the extremely low μ road control is executed, the normal acceleration slip control target opening is always obtained. Here, m represents the period KT shown in step 540 later.

Next, at step 510, the vehicle
TRC is calculated by adding the offset amount THI of the uniform opening obtained from the engine performance to the target opening TRC (m).
(M) + THI is updated and the throttle valve is driven.

Next, at step 520, it is judged whether or not the time KD has elapsed, and while the time KD has elapsed, as shown in FIG. 9, the processing in which the opening is set to TRC (m) + THI is continued. This KD is a value experimentally obtained from the vehicle / engine performance.

When the time KD has elapsed, the routine proceeds to step 530, where the reference target opening TRC calculated at step 500.
TR to (m) using the offset amount THD of the uniform opening.
Update C (m) -THD and drive the throttle valve.

Next, at step 540, it is judged whether or not the time KT-KD has elapsed, with KT being the experimentally obtained basic cycle of this control, and as shown in FIG. 9, the time KT-K is obtained.
While D has elapsed, processing for continuing the state in which the opening is TRC (m) -THD is performed.

When time KT-KD has elapsed, step 5
Returning to 00, the above processing is repeated for TRC (m + 1).

FIG. 10 shows the state of this extremely low μ road control.

The first method of the extremely low μ road control reflects the target opening calculated by the normal acceleration slip control to some extent, and controls the values of time KT, KD or THI and THD to control performance. It is possible to comply with the emphasis on acceleration or the emphasis on stability and control feeling.

Next, the second method for controlling the extremely low μ road will be described. This second method is shown in the flowchart of FIG. In step 600 of FIG. 11, a target opening used in normal acceleration slip control is calculated and the throttle valve is driven.

In the next step 610, it is judged whether or not the time KD has elapsed, and when the time KD has elapsed, the next step 62
If not, the process returns to step 600 to repeat the process. That is, in steps 600 and 610, the normal acceleration slip control for the KD time is executed.

In step 620, the target opening is forcibly fully closed to drive the throttle. Alternatively, since the target opening may already be fully closed on the extremely low μ road, fuel cut (for example, all cylinder cut) may be used in combination within a range where engine stall does not occur. Alternatively, in a system that does not use a throttle such as a diesel engine, only this fuel cut is performed.

In the next step 630, it is determined whether or not the time KT-KD has elapsed, as in step 540 of the first method. If KT-KD has elapsed, step 6 is executed.
Return to 00, and if not elapsed, continue the process of step 620.

In the second method, the target slip ratio can be increased in advance to make it easier to obtain the effect of FIG.

As described above, in this embodiment, by varying the throttle opening, it is possible to vibrate the engine output control amount and improve the acceleration at the time of starting. Further, by reflecting the normal control, it is possible to adapt to emphasis on acceleration or stability.

When the vehicle cannot accelerate on an extremely low μ road,
In the conventional control, by the feedback control aiming at the constant slip ratio as described above, even if the accelerator is stepped on (the engine does not start due to slip), the engine is kept at the minimum rotation speed, which may give the driver a feeling of discomfort. In this embodiment, since the engine rotation changes,
The discomfort can be alleviated.

[0067]

As described above, according to the present invention,
By vibrating the engine output control amount in a predetermined cycle, the drive wheels repeat large slips and small slips, so even if the road surface has an irregular road surface μ or an extremely small road surface μ, a large driving force is generated somewhere. It is possible to improve the acceleration at the time of starting. Further, when the correction amount is added based on the value in the normal acceleration slip control, the normal control can be reflected, and it can be adapted to the importance of acceleration or stability.

[Brief description of drawings]

FIG. 1 is a block diagram showing the gist of the present invention.

FIG. 2 is a schematic configuration diagram of a vehicle including an acceleration slip control device of the present invention.

FIG. 3 is a flowchart showing the processing of the first embodiment of the present invention.

FIG. 4 is a flowchart showing the processing of the second embodiment of the present invention.

FIG. 5 is a flowchart showing the processing of the third embodiment of the present invention.

FIG. 6 is a flowchart showing the processing of the fourth embodiment of the present invention.

FIG. 7 is a block diagram showing an example of engine output control amount vibrating means of the present invention.

FIG. 8 is a flowchart showing a first method of extremely low μ road control according to the present invention.

FIG. 9 is a diagram showing control of throttle opening by extremely low μ road control according to the present invention.

FIG. 10 is a diagram showing a state of extremely low μ road control according to the present invention.

FIG. 11 is a flow chart showing a second method of extremely low μ road control according to the present invention.

FIG. 12 is a diagram showing a state of conventional throttle opening control.

[Explanation of symbols]

 18 ... Engine 36 ... Main throttle valve 40 ... Engine control device 42 ... Sub throttle valve 44 ... Step motor 46 ... Electronic control device 48, 49 ... Drive wheel vehicle speed sensor 50, 52 ... Driven wheel vehicle speed sensor

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[Procedure amendment]

[Submission date] December 16, 1994

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 4

[Correction method] Change

[Correction content]

[Figure 4]

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Kato 1-1-1, Showa-cho, Kariya city, Aichi Prefecture Nihondenso Co., Ltd.

Claims (3)

[Claims] Claim: What is claimed is: 1. An acceleration slip control device comprising: an acceleration slip detection means for detecting the occurrence of an acceleration slip on a drive wheel; and a means for controlling an engine output when the acceleration slip is detected. A road surface condition detecting means for detecting whether or not the road surface condition detecting means detects a low friction road surface, and a control amount of the engine output at the time of acceleration slip detection based on a road surface which is not a low friction road surface, An acceleration slip control device comprising: means for vibrating at a predetermined cycle; 2. A control amount correction for adding a predetermined increase correction amount and a predetermined decrease correction amount to a control amount of the engine output in a predetermined cycle by means for vibrating the control amount of the engine output in a predetermined cycle. An acceleration slip control device characterized by being a means. 3. The control means according to claim 1, wherein the means for vibrating the control amount of the engine output in a predetermined cycle is a control amount correcting means for making the control amount of the engine output substantially zero in a predetermined cycle. Acceleration slip control device.