JPH0678736B2 - Vehicle acceleration slip controller - Google Patents

Description

The present invention relates to an acceleration slip control device for a vehicle. More specifically, the present invention relates to an acceleration slip control device for a vehicle that detects a rotation state of drive wheels and controls a throttle valve in accordance with the rotation state to suppress engine output and perform optimum acceleration slip control. is there.

[Prior Art] Starting and running on a road surface having a low coefficient of friction such as on ice or a snowy road is very dangerous because the vehicle may slip to the back or the vehicle spins due to slip of driving wheels. Therefore, in order to increase the frictional force between the tire and the road surface, spike tires, chains, etc. have been conventionally installed.

A traction control system that suppresses the slip of the driving wheels is also considered, and the slip ratio [(vehicle speed-driving wheel speed) / driving wheel speed] is set to -0.1 to maximize the frictional force with the road surface. The engine output is controlled so that it is controlled to around 0.2.

[Problems to be Solved by the Invention] In this type of traction control system, the engine output is controlled based only on the slip ratio.

However, when the vehicle speed and the driving wheel speed are equalized by the control, that is, the shock applied to the vehicle body when the tire grips the road surface, not only the slip ratio before the control but also the friction coefficient of the road surface changes. For example, on a so-called high μ road where the road surface has a large friction coefficient, the engine output is low μ
When the restraint control is performed similarly to the road, the driving wheel speed is drastically reduced as compared with the low μ road. As a result, the shock when the tire grips the road surface may increase.

Further, in this type of traction control system, in order to obtain good acceleration, the engine output is controlled in the increasing direction even during the engine output suppression control. In this case, since the drive wheel speed does not easily decrease on the low μ road, the drive wheel speed may increase before the tire grips the road surface, and the slip ratio may increase again.

Therefore, an object of the present invention is to provide an acceleration slip control device for a vehicle, which can reduce a shock when a tire grips a road surface on both a high μ road and a low μ road and can surely perform slip control. Made

[Means for Solving the Problems] The present invention, which has been made in order to achieve the above object, includes, as shown in FIG. 1, a drive wheel rotation state detecting means for detecting a rotation state of a drive wheel, and the detected drive. A slip state detecting means for detecting the slip state of the drive wheel based on the rotation state of the wheel, and an intake system of the engine for suppressing the slip of the drive wheel when the slip state of the drive wheel is detected In an acceleration slip control device for a vehicle, which comprises an opening / closing control means for controlling the opening / closing of a throttle valve, when the opening / closing control of the throttle valve is executed by the opening / closing control means, based on the detection result of the drive wheel rotation state detecting means. Maximum acceleration detecting means for detecting the maximum value of the driving wheel acceleration, and that the larger the maximum value of the detected driving wheel acceleration, the smaller the friction coefficient of the road surface. Constant to, among the above switching control is for the gist acceleration slip control device, the vehicle and having a opening speed control means for controlling so as to slow down the opening speed of the throttle valve.

[Operation] In the present invention having such a configuration, the opening / closing control unit controls the opening / closing of the throttle valve based on the detection result of the slip state detection unit to reduce the drive torque and suppress the slip. For example, when the slip of the driving wheels becomes excessive, the throttle valve is controlled to be closed to reduce the engine torque,
When the slip of the drive wheels is approaching convergence, the throttle valve is controlled to open to control the engine torque in the increasing direction. In this way, the throttle valve is controlled to be opened and closed to suppress the engine torque and prevent slip.

On the other hand, the opening speed control means, based on the maximum value of the driving wheel acceleration detected by the maximum acceleration detection means, of the opening and closing control,
The opening speed of the throttle valve is controlled as follows. That is, generally, the maximum value of the driving wheel acceleration detected when the opening / closing control of the throttle valve for slip suppression is executed has a good correlation with the friction coefficient of the road surface, and the maximum value is large. It is known that the road surface has a smaller friction coefficient. This means that the smaller the friction coefficient on the road surface, the smaller the frictional force that hinders the rotation of the drive wheels, and that the drive wheel acceleration does not immediately decrease even if the drive torque decreases due to opening / closing control of the throttle valve. caused by. Therefore, it is estimated that the larger the maximum value of the driving wheel acceleration detected by the maximum acceleration detecting means, the smaller the friction coefficient of the road surface, and the smaller the estimated friction coefficient of the road surface, the slower the opening speed of the throttle valve. Control.

Therefore, on a low μ road where the drive wheel speed is unlikely to decrease, the increase in engine torque can be slowed down, the time during which the drive wheel speed continues to decrease can be extended, and the tire can be reliably gripped on the road surface. On the other hand, on a high μ road, the engine torque can be increased quickly, the drive wheel speed can be gently reduced, and the shock when the tire grips the road surface can be reduced.

[Examples] The present invention will be described below with reference to the drawings with reference to Examples.

FIG. 2 is a schematic configuration diagram of one embodiment, in which the present invention is applied to a front engine / rear drive (FR type) vehicle equipped with a gasoline engine. In the figure, 1 is a 4-cylinder fuel injection engine, 2 is an intake pipe, 3
Is an air flow meter, 4 is a fuel injection valve provided for each cylinder that injects fuel into intake air, and 5 is a spark plug (secondary
In the figure, the fuel injection valve 4 and the spark plug 5 are shown only for one cylinder. ), 6 is a distributor that supplies a high voltage to the spark plug, 7 is an engine speed sensor consisting of a gear and an electromagnetic pickup, and 8 is driven by a accelerator pedal 9 via a link mechanism to adjust the intake amount. The main throttle valve, 10 is a sub-throttle valve that is provided upstream of the main throttle valve 8 and adjusts the intake air amount,
Reference numeral 11 is a DC motor for driving the sub throttle valve, 12 is a main throttle sensor for detecting the throttle valve opening of the main throttle valve 8, and 13 is a sub throttle sensor for detecting the throttle opening of the sub throttle valve 10.
The throttle sensors 12 and 13 are turned on when the throttle valves 8 and 10 are in the fully closed position, respectively.

On the other hand, 20 and 21 are left and right drive wheels, which are the rear wheels of the vehicle, respectively, and the power of the engine 1 is transmitted through the transmission 22, the propeller shaft 23 and the like. Reference numerals 24 and 25 denote a left drive wheel speed sensor and a right drive wheel speed sensor, which detect the rotational speeds of the left drive wheel 20 and the right drive wheel 21, respectively. 26 and 27 are left and right idler wheels that are rotated as the car runs, 28 and 29
Represent left and right idler wheel speed sensors, respectively.

The sensors 24, 25, 28, 29 are composed of gears and electromagnetic pickups.

Reference numeral 30 indicates an electronic control circuit.

Here, assuming that the electronic control circuit 30 is configured by using a microcomputer, and proceeding with the description, the configuration of the electronic control circuit 30 can be represented as shown in FIG. In the figure, 31 is a central processing unit (CPU) that inputs and calculates data detected by each sensor according to a control program and performs processing for driving and controlling the DC motor 11, and 32 is a control program, a map, or the like. Read-only memory (ROM) that stores data, 33 is a random access memory (RAM) that temporarily reads and writes data from each sensor and data required for arithmetic control, 3
4 is an input unit including a waveform shaping circuit and a multiplexer that selectively outputs the output signal of each sensor to the CPU 31, 35 is an output unit including a drive circuit that drives the DC motor 11 according to a control signal from the CPU 31, 36 Is a bus line connecting each element such as the CPU 31, ROM 32 and the like, the input section 34 and the output section 35 to serve as a passage for various data, and 37 is a power supply circuit for supplying power to each of the above sections.

Next, the operation of the electronic control circuit 30 will be briefly described. Left drive wheel speed sensor 24, right drive wheel speed sensor 25
Also, by receiving various detection signals from the left idle wheel speed sensor 28, the right idle wheel speed sensor 29, etc., the opening of the sub-throttle valve 10 is adjusted so that maximum acceleration can be obtained without acceleration slip during vehicle acceleration. Slip control is executed to output a drive signal to the DC motor 11 and suppress the engine output.

Further, as is well known, the PCU 31 inputs the data of the intake air amount detected by the air flow meter 3 and the engine speed detected by a rotation angle sensor (not shown) through the input unit 34, and from these data, the basic fuel is input. Calculate the injection amount. Then, this basic fuel injection amount is corrected by the residual oxygen concentration in the exhaust gas detected by an oxygen sensor (not shown), and the actual fuel injection amount is calculated. Then, the fuel injection valve 4 is controlled on the basis of this actual fuel injection amount, and fuel injection, that is, fuel supply suitable for the operating state of the engine is performed.

Similarly, based on the engine speed, intake air amount, etc., the optimum ignition timing is calculated using, for example, the data map in the ROM 32, and the ignition timing signal is sent to the igniter (not shown) based on this, Ignition timing control is performed according to the operating state of the engine such as the number.

Next, the acceleration slip control executed by the electronic control circuit 30 configured as described above will be described with reference to the flowchart of the main routine shown in FIG. First, the outline of the processing will be described. The processing is roughly divided into the following three processing. That is, as shown by the arrow in the figure, a process for holding the opening of the sub-throttle valve 10, that is,
This is a process performed when the driving wheel acceleration is positive and is smaller than a positive predetermined value.

This is a process for controlling the closing of the sub-throttle valve 10, that is, a process which is performed when the driving wheel acceleration is larger than a positive predetermined value, whereby the engine output is suppressed.

This is a process for controlling the opening of the sub-throttle valve 10, that is, a process that is performed when the driving wheel acceleration is negative to increase the engine output and slow down the driving wheel speed.

These processes are performed by determining the driving wheel acceleration, but since the driving wheel acceleration repeats positive and negative, →→
→ processing is executed in one cycle. Next, these processes will be described in detail with reference to FIGS.

Process of (a) First, in step 101, the DC motor 11 is driven so that the sub throttle valve 10 is fully opened. This is a process for surely fully opening the sub-throttle valve 10 at the start of the main routine, although the sub-throttle valve 10 is always fully open at the end of control. Next, at step 102, it is judged if the main throttle sensor 13 is on, that is, whether the main throttle sensor 13 is idling or accelerating. If “YES”, that is, if idling is determined, the process returns to step 101. Since the process is accelerating here, it is determined to be "NO", and the routine proceeds to step 103, where the average value VωF of the left and right idle wheel speeds, the idle wheel acceleration ωF, the left drive wheel speed VωRL, and the right drive wheel speed VωRR. Then, the left drive wheel acceleration ωRL, the right drive wheel acceleration ωRR, the main throttle opening θH, and the sub throttle opening θS are calculated.

Next, at step 104, the idle wheel speed VωF (considered as the vehicle speed) is set to the control end vehicle speed VMAX, for example, 100 Km / H.
Determine if less than. If it is determined to be "NO", the process returns to step 101. Here, "YES", that is, 100 Km / H
Since it is smaller, it proceeds to step 105. In this step, it is determined whether the right drive wheel acceleration ωRR is larger than the left drive wheel acceleration ωRL. That is, it is determined which of the left and right drive wheel accelerations has the larger slip. "YE
If it is determined to be "S", in step 106, the right driving wheel acceleration ωRR is set as the driving wheel acceleration ωR. If "NO" is determined, the left driving wheel acceleration ωRL is similarly set as ωR in step 107. In this way, the drive wheel with large slip is selected, and slip control is performed by this.

Next, at step 108, it is judged if the driving wheel acceleration ωR is larger than a predetermined value A or not. That is, it is determined whether or not the state is immediately before slip. Here, the determination is “NO”, and the process jumps to step 109. That is, the slip is not generated, and the process of holding the sub throttle valve is performed.
In step 109, it is determined whether the driving wheel acceleration ωR is negative. Here, since the vehicle is accelerating, it is determined to be "NO", the routine jumps to step 110, holds the auxiliary throttle valve opening θS, returns to step 102, and performs similar processing.

Process of (b) In such a loop process, the driving wheel acceleration increases as shown in FIG. Therefore, drive wheel acceleration ω
Since R exceeds A, in step 108 of the above loop processing, it is determined to be "YES" this time, and the process jumps to step 111. Here, the second throttle valve opening is reduced to θCLOSE. In this embodiment, θCLOSE is zero, that is, the fully closed state. Therefore, as shown in FIG. 5C, the sub-throttle valve 10 is driven from the fully open state to the fully closed state by the DC motor 11, and the fully closed state is maintained.

Next, at step 112, it is judged if the drive wheel acceleration ωR is larger than the maximum value ωRMAX of the drive wheel acceleration up to the previous time. Here, since the driving wheel acceleration ωR has not reached the maximum value and is increasing, it is determined to be “YES” and the process jumps to step 113. Here, the driving wheel acceleration ωR in step 112 is set as the maximum value ωRMAX of the driving wheel acceleration, On the other hand, "NO"
If it is determined that step 113 is jumped to step 1
Return to 02. That is, steps 112 and 113 are processes for detecting the maximum value ωRMAX of the driving wheel acceleration.

When the loop processing of the processing of (c) is performed, the driving wheel acceleration ωR decreases after reaching the maximum value of the driving wheel acceleration and becomes smaller than the predetermined value A, so that it is determined as “NO” in step 108, and step 109 is executed. Since the driving wheel acceleration is positive in this case, the operation jumps to step 110, and the auxiliary throttle valve 10 is held in the fully closed state as described above.

By the processing of (d), the driving wheel acceleration ωR decreases, and this time, in step 109, it is determined to be “YES” and jump to step 114, and the difference between the driving wheel speed VωR and the idle wheel speed VωF is ΔVω. Set as. Then in step 115,
The opening speed VM of the sub-throttle valve 10 is set by the following equation as shown in FIG.

VM = −KΔVω ・ ωRMAX + B where ΔVω is the value obtained in step 114, ωRMAX
Is a value obtained in step 113, and K and B are constants.

This is because the driving wheel acceleration decreases and VωR =
This is to reduce the shock when it reaches VωF.
This shock occurs because the frictional force between the tire and the filter surface increases when the tire grips the road surface, and the driving force increases. In addition, the reason why VM is changed by ΔVω is that the degree of decrease in driving wheel speed differs between small slip and excessive slip, and accordingly, the slope of the straight line is changed as shown in FIG. It is changed according to ΔVω.

Further, the reason why the value is changed also by ωRMAX is that when the same high friction coefficient road (high μ road) as shown in FIG.
VωR becomes V by changing the opening speed VM by ω
By providing a time difference TH to the time until it becomes equal to ωF, it is possible to mitigate the shock that occurs when the slip is large, but on the high μ road and the low friction coefficient road (low μ road), the same slip size is obtained. Further, there is a time difference TL in the time from when VωR becomes equal to VωF. Therefore, the time difference TL is dealt with by detecting ωRMAX having a correlation with the road surface friction coefficient. That is, when ωRMAX is large like on a low μ road, the opening speed VM is controlled to be slowed to extend the time during which the drive wheel speed continues to decrease, and the drive wheel speed is increased before the tire grips the road surface with certainty. It is possible to prevent the increase. On the contrary, like the high μ road, ωRM
When AX is small, the opening speed VM is increased to gently reduce the drive wheel speed, and the shock when the tire grips the road surface can be reduced.

Next, at step 116, the sub-throttle valve 10 is opened to the opening θH value of the main throttle valve 8 at the opening speed VM. In the following step 117, the auxiliary throttle valve 10
Since the opening has been completed, the maximum value of the driving wheel acceleration is set to zero and initialized.

Then, at step 118, the opening θ of the throttle valve 10
It is determined whether the elapsed time TS in which S is held at θH is larger than a predetermined value TOP. Since it is determined to be "NO", the process returns to step 102 and loop processing is performed.

In this way, the sub-throttle valve 10 is gradually opened,
When the engine output rises, the driving wheel acceleration rises, and it is determined to be "NO" in step 109, and the first process starts again. In this way, the processes of (a), (b), (c), and (d) are repeatedly performed, and the driving wheel acceleration gradually converges, so that the driving wheel speed also converges.

Therefore, the driving wheel acceleration does not exceed the predetermined level A, and it is determined that the driving wheel acceleration is suppressed, and the processing is repeated. Therefore, in step 118, "YES"
The processing returns to 101 and the sub-throttle valve 10 is fully opened, and thereafter 102 → 103 → 104 → 105 → 106 (or 10
7) → 108 → 109 → 110 loop processing is performed, and the sub-throttle valve 10 is held in the fully open state as shown in FIG.

In this embodiment, the left and right drive wheel speed sensors 24 and 25 correspond to drive wheel rotation state detecting means. Also, step 103
~ 109 to the slip state detecting means, steps 110, 111 and 116 to the opening and closing control means, steps 112 and 113 to the maximum acceleration detection means, further step 115 to the opening speed control means,
These are corresponding processes.

As described above, according to the present embodiment, the intake air amount of the engine can be controlled by using the sub-throttle valve 10 for the engine output control, so that the engine output control range is maintained while the air-fuel ratio is kept at the optimum value. Get wider Even if the sub throttle valve 10 fails, the main throttle valve 8
Normal operation is possible at.

Since the drive wheel acceleration is used to detect the slip of the drive wheel, the detection can be speeded up. Further, since the opening control of the sub-throttle valve 10 is performed from the position where the driving wheel acceleration is negative, accurate control can be performed in consideration of the rise of torque and the delay of the drive system. Further, ΔV indicating the degree of slip
Since the opening speed VM is changed by ω, the driving wheel speed Vω
It is possible to reduce the shock when the decrease in R slows down and the drive wheel speed VωR becomes equal to the idle wheel speed VωF, that is, when the tire grips the road surface.

In addition, the opening speed VM is determined by the maximum value ωRMAX of the driving wheel acceleration.
Therefore, on low μ roads where the drive wheel speed does not easily decrease, by controlling the opening speed VM slowly, the time during which the drive wheel speed continues to decrease can be extended, and the tire can be reliably gripped on the road surface. it can. Conversely, on high μ roads, the opening speed VM
By increasing the speed, the drive wheel speed can be gently decreased, and the shock when the tire grips the road surface can be reduced.

Therefore, good slip control can be realized on both the high μ road and the low μ road.

Although the specific embodiments of the present invention have been described above, the present invention is not limited to such embodiments, and various embodiments are included within the scope of the claims. For example, the present invention can also be applied to a front engine front drive (FF system).

[Effects of the Invention] The present invention has the following excellent effects. That is, on a low μ road where the driving wheel speed is hard to decrease, the increase of the engine torque can be slowed down, the time for which the driving wheel speed continues to decrease can be extended, and the tire can be surely gripped with the road surface. On the other hand, on a high μ road, the engine torque can be increased quickly, the drive wheel speed can be gently reduced, and the shock when the tire grips the road surface can be reduced.

Therefore, in the present invention, in both high μ road and low μ road,
It is possible to reduce shock when the tire grips the road surface and to perform reliable slip control.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram, FIG. 2 is a schematic configuration diagram of an embodiment of the present invention, FIG. 3 is a block diagram of an electronic control circuit, and FIG. 4 is a flowchart showing a control program content of the electronic control circuit. FIG. 5 is a timing chart of the drive wheel speed, drive wheel acceleration, and throttle opening, and FIG. 6 is the product ΔVω of the difference between the opening speed VM, the drive wheel speed, and the idle wheel speed, and the maximum value ωRMAX of the drive wheel acceleration.・ A graph showing the relationship with ωRMAX,
FIG. 7 is a timing chart of driving wheel speed and driving wheel acceleration on a high μ road and a low μ road, respectively. 8 …… Main throttle valve 9 …… Accelerator pedal 10 …… Sub throttle valve 11 …… DC motor 12 …… Main throttle sensor 13 …… Sub throttle sensor 24 …… Left drive wheel speed sensor 25 …… Right drive wheel speed sensor 30 ... Electronic control circuit

Claims (1)

[Claims] 1. A drive wheel rotation state detecting means for detecting a rotation state of a drive wheel, a slip state detecting means for detecting a slip state of the drive wheel based on the detected rotation state of the drive wheel, and the drive method. An acceleration slip control device for a vehicle, comprising: an opening / closing control means for controlling opening / closing of a throttle valve provided in an intake system of an engine so as to suppress slip of the driving wheels when a slip state of the wheels is detected. When the opening / closing control of the throttle valve by the means is being executed, the maximum acceleration detecting means for detecting the maximum value of the driving wheel acceleration based on the detection result of the driving wheel rotation state detecting means, and the maximum of the detected driving wheel acceleration. It is estimated that the larger the value, the smaller the friction coefficient of the road surface, and the opening speed of the throttle valve is controlled to be slower in the opening / closing control. An acceleration slip control device for a vehicle, comprising: