JPH0575896B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for preventing vehicle acceleration slip;
More specifically, the present invention relates to a method for preventing acceleration slips in a vehicle, which detects acceleration slips in drive wheels based on the speed of the drive wheels of the vehicle, and prevents acceleration slips by reducing the output of an internal combustion engine.

[Conventional technology]

Conventionally, acceleration slips that occur when a vehicle accelerates suddenly, such as when starting or running, have been prevented by the driver sensing the acceleration slip and controlling the accelerator operation.

Therefore, in recent years, research has been conducted on control methods to automatically prevent such acceleration slips.
One idea is to use an electronically controlled internal combustion engine control device that controls the ignition timing, etc., to control the engine output so that acceleration slip does not occur, that is, the drive wheel torque does not exceed the road friction force. ing.

By the way, with regard to this type of acceleration slip prevention method, research has mainly focused on methods for detecting acceleration slips. Various methods have been proposed, such as detecting slips, or detecting only the wheel speed of the driving wheels and detecting acceleration slips based on temporal changes in the wheel speeds. There has not been much research into the point at which control processing for engine output should be ended after it has started, and the only thing that has been done is to say that the control processing should end when the slip subsides. It hadn't been thought of. (Refer to Japanese Unexamined Patent Publication No. 59-68537.) [Problem to be Solved by the Invention] Here, after the output reduction control of the internal combustion engine is started due to the occurrence of an acceleration slip, the driver cancels the slip. In order to prevent this, if we reduce the amount of pressure on the accelerator pedal, and as a result, the opening of the throttle valve installed in the intake passage of the internal combustion engine decreases, in that case, the reduction in output due to the driver's operation will occur. This overlaps with the decrease in output due to output reduction control. In other words, a greater reduction in output is performed than in the state in which slip is prevented only by the output reduction control described above. Therefore, in such a state, the degree of decrease in the drive wheel speed is also large due to the large amount of output reduction.

In the above-mentioned conventional technology, the output reduction control is continued until the slip subsides, so a large output reduction due to overlapping output reductions continues until the slip subsides.

Therefore, with this conventional technology, even if it is determined that the slip has converged and the output reduction control is terminated, due to the large degree of decrease in the driving wheel speed until the end of the output reduction control, the However, there is a problem in that the driving wheel speed decreases, resulting in deterioration of acceleration performance.

Therefore, the present invention has been made in view of the above points, and when the throttle valve opening of the internal combustion engine becomes less than a predetermined opening due to the driver's return operation of the accelerator pedal, the slip of the drive wheel is By ending the output reduction control to prevent
The purpose is to be able to suppress acceleration slip well without reducing acceleration performance.

[Structure of the invention]

In order to achieve this object, the present invention has the following features: When an acceleration slip of a drive wheel of a vehicle is detected based on the drive wheel speed, output reduction control is started to reduce the output of an internal combustion engine mounted on the vehicle. In the acceleration slip prevention method for a vehicle, after the output reduction control is started, the opening degree of a throttle valve installed in an intake passage of the internal combustion engine is lowered to a predetermined opening degree by the driver's return operation on the accelerator pedal. The present invention is characterized in that the output reduction control is terminated when the following state occurs.

[Effect]

When an acceleration slip of the driving wheels of the vehicle is detected based on the driving wheel speed of the vehicle, an output reduction control is started to suppress the output of the internal combustion engine mounted on the vehicle, and after the output reduction control is started. , when the opening degree of a throttle valve installed in the intake passage of the internal combustion engine becomes a predetermined opening degree or less due to the driver's return operation of the accelerator pedal, the output reduction control is terminated. Therefore, it is possible to prevent an excessive drop in output when the driver attempts to prevent acceleration slip by operating the accelerator.

〔Example〕

The present invention will be explained below by giving an example and referring to the drawings.

First, FIG. 1 is a schematic system diagram showing a four-cycle, four-cylinder internal combustion engine and its peripheral equipment in an embodiment to which the method of the present invention is applied.

1 is an engine, 2 is a piston, 3 is a spark plug, 4 is an exhaust manifold, 5 is an oxygen sensor provided in the exhaust manifold 4 and detects the residual oxygen concentration in the exhaust gas, 6 is provided for each cylinder and indicates a fuel 7 is an intake manifold, 8 is provided in the intake manifold 7,
1 is an intake air temperature sensor that detects the temperature of intake air sent to the engine body 1; 9 is a water temperature sensor that detects the engine cooling water temperature; 10 is a throttle valve;
1 is a throttle position sensor that is linked to the throttle valve 10 and outputs a signal according to the throttle opening degree; 12 is a bypass passage that is an air passage that bypasses the throttle valve 10; and 13 is an opening area of the bypass passage 12. An idle speed control valve (ISCV) controls the idle rotation speed, 14 represents an air flow meter that measures the amount of intake air, and 15 represents an air cleaner that purifies the intake air.

Further, 16 is an igniter that is equipped with an ignition coil and outputs the high voltage necessary for ignition, and 17 is a device that is linked to a crankshaft (not shown) and distributes the high voltage generated by the igniter 16 to the spark plugs 3 of each cylinder. A triviewer 18 is installed within the distributor 17, and the distributor 1
A rotation angle sensor 19 outputs 24 pulse signals (crank angle signals) per one revolution of the distributor 17, that is, two revolutions of the crankshaft.
a cylinder discrimination sensor 20 that outputs a pulse signal;
21 represents an electronic control circuit, and 21 represents a vehicle speed sensor that is provided on a propeller shaft (not shown) that transmits the power generated by the engine 1 to the driving wheels, and outputs a signal according to the rotation of the driving wheels.

Furthermore, 22 indicates a passage for air to flow bypassing the throttle valve when the engine is cold, that is, a first idle bypass passage, and 23 indicates an air valve that controls the amount of air passing through the first idle bypass passage 22. The air valve 23 operates to open the first idle bypass passage 22 in order to secure the engine rotational speed necessary for warm-up operation when the engine is cold.

Next, FIG. 2 shows a block diagram of the electronic control circuit 20. As shown in FIG.

30 is a central processing unit (CPU) which inputs and calculates data output from each sensor according to a control program, and performs processing to control the operation of various devices such as the fuel injection valve 6 and the igniter 16; A read-only memory (ROM) 32 stores data such as the control program and a map for calculating the ignition advance angle, and a read-only memory (ROM) 32 is used to temporarily read and write data input to the electronic control circuit 20 and data necessary for calculation control. 33 is a backup random access memory (RAM) backed up by a battery so as to retain data necessary for subsequent engine operation even if a key switch (not shown) is turned off; Reference numeral 34 includes an input port (not shown), a waveform shaping circuit provided as necessary, a multiplexer that selectively outputs the output signal of each sensor to the CPU 30, an A/D converter that converts an analog signal into a digital signal, etc. Each of the input units provided therein is shown. Reference numeral 35 indicates an input/output port provided with an output port in addition to an input port (not shown), and a drive circuit for driving the fuel injection valve 6, igniter 16, etc. according to control signals from the CPU 30 as necessary. Section 36 is
Each element such as CPU 30, ROM 31, etc. and input section 3
4. Each represents a bus line connecting the input/output section 35 and through which each data is sent.

In the engine control device of this embodiment having the above-described configuration, the fuel injection amount, ignition timing, etc. are controlled according to the operating condition based on the detection signals from the above-mentioned sensors. Detection of acceleration slip and accompanying engine output control, which are the main processes according to the present invention, will now be explained with reference to the flowcharts shown in FIGS. 3 and 4. In this embodiment, the ignition timing is controlled as a means for controlling the engine output during acceleration slip.

First, FIG. 3 shows acceleration slip detection processing that is executed every time a signal (hereinafter referred to as a vehicle speed pulse) is output from the vehicle speed sensor 21 in response to the rotation of the drive wheels.

When the process is started, first, in step 101, a process is performed to calculate the time interval from the previous process to the current process, that is, the time interval Tn of vehicle speed pulses, and the process moves to the following step 102. Then, in step 102, the amount of change α in the driving wheel speed is calculated from the time interval T(n-1) of vehicle speed pulses obtained in the previous process and the time interval Tn obtained in step 101. It is obtained from the formula α=Tn/T(n-1), and the process moves to the following step 103.

In step 103, it is determined whether the amount of change α is smaller than a preset value _K1 . When α<K ₁ , that is, the wheel speed increases rapidly, and the time interval Tn of vehicle speed pulses increases.
If the value suddenly decreases, it is determined that an acceleration slip has occurred, and the process moves to the following step 104.
On the other hand, if α≧K ₁ , it is determined that no acceleration slip has occurred, and the processing of this routine is terminated.

When it is determined in step 103 that an acceleration slip has occurred and the process in step 104 is executed, a permission flag Fθ is set to permit execution of ignition timing retard control, which will be described later. And step 1
05, and the setting time K ₂ used to end the ignition timing retard control, which will be described later, is set, for example, as shown in FIG. It is calculated from characteristic map A or an arithmetic expression. In Fig. 5, A is the engine speed Ne
and set time _K2 are in a proportional relationship, and B is a proportional relationship only when engine speed Ne and set time _K2 are less than or equal to a predetermined engine speed,
Graph C shows a graph in which the set time K ₂ becomes a constant value when the engine speed exceeds that speed, and C shows a graph in which the set time K ₂ increases more as the engine speed Ne increases. The type of graph indicates that, for example, the following map may be used as the map A used in setting the above-mentioned setting time _K2 , but in reality, it should be set experimentally depending on the vehicle. Bye.

Next, in step 106, the above step 1 is performed.
Similarly to 05, the ignition retard amount △θ used in the ignition timing retard control described later is calculated using the map B or the calculation formula as shown in Fig. 6 using the engine speed Ne as a parameter, and the processing of this routine is completed. .

Next, Fig. 4 shows a series of conventional engine controls such as fuel injection amount control and ignition timing control, which are performed as one of a series of engine controls such as fuel injection amount control and ignition timing control. 2 is a flowchart representing a control program for suppressing.

When the process starts, first, in step 201, an acceleration slip is detected by the acceleration slip detection process shown in FIG. 3, and in step 104, it is determined whether the retard control permission flag Fθ is set. Execute the judgment. and the permission flag
If F.theta. is not set and is in a clear state, the main retard control is immediately finished and the process moves to the next process.On the other hand, if the permission flag F.theta. is in a set state, the process moves to the next step 202.

In step 202, the flag Ft, which is set when the ignition timing retard control is executed for the first time after an acceleration slip is detected, and is cleared when the retard control ends, is checked by the process described later, to see if it is in a clear state. Executes a determination of whether or not the Here, we will proceed assuming that the main retard control is executed for the first time after an acceleration slip is detected.
Since Ft has remained in the same state since it was cleared at the end of the previous retard control, this step 202
In step 203, the determination is ``YES'', and the process moves to the following step 203.

In step 203, the current time _T1 at the start of the retard control is read out from a free running timer or the like and stored in a predetermined area of the RAM 32, and the process proceeds to step 204.
Then, in step 204, the above flag Ft
is set, and a process is executed to instruct that retard control is being executed for the next process.

When the permission flag Fθ is set in this way and the main retard control is executed for the first time, the processes in steps 201 to 204 are executed, followed by the ignition timing correction process in step 205, and the main retard control process is executed. It will end once. Here, the ignition timing correction processing in step 205 means to calculate the ignition timing determined based on the engine operating condition in a known routine (not shown) using the ignition retard amount Δθ determined in step 106 in FIG. This is to retard the engine output and control the engine output to the extent that acceleration slip can be suppressed, and this operation will be explained in detail later.

Next, flag Ft is set once, and step 2
After the ignition timing correction process in step 05 is executed, when the process moves to the main retard control, the determination in step 202 is "NO" and step 206 is executed. Then, in step 206, the current time _T2 is read, and in the following step 207, this time _T2 and the time already read in the process of step 203 are read.
From _T1 , the elapsed time Tm after the start of the main retard control is calculated from the following formula: Tm= _T2 - _T1 .

Next, in step 208, the above step 2 is performed.
By comparing the elapsed time Tm calculated in step 07 with the set time _K2 set in step ₁₀₅ in FIG. Determine whether or not Tm
If ≧K ₂ , the process moves to the subsequent step 209.
In step 209, it is determined whether the throttle opening degree S determined based on the signal from the throttle position sensor 11 is greater than or equal to a predetermined value _K3 , and if S≧ _K3 , step 20 is performed.
5, the ignition timing correction process is executed again. On the other hand, if it is determined in step 208 that Tm<K ₂ or in step 209 that S<
If it is determined as K ₃ , the process moves to the subsequent step 210, clears the retard control permission flag Fθ and the flag Ft indicating whether or not retard control is being executed, and ends this control process. .

Next, the operation according to the above control program will be explained with reference to FIGS. 7 and 8.

FIG. 7 is a time chart showing the change in the vehicle speed pulse output from the vehicle speed sensor 21 and the amount of retardation Δθ. As shown in the figure, the time interval of the vehicle speed pulse changes from T(n-) to Tn. It changes rapidly and α(=
Tn/T( _{n - 1} ))
The ignition timing retard amount is set to Δθ until the ignition timing becomes equal to or less than a predetermined value, and the ignition timing is retarded. As shown in Fig. 8, when the ignition timing θ is retarded by Δθ, for example from θ ₁ to θ ₂ , the engine output P is suppressed from P ₁ to P ₂ , and acceleration slip is prevented. . The reason why time _K2 is determined by using the engine speed at the time when acceleration slip is detected as a parameter is to set the retard control time according to the degree of acceleration slip. This is because the larger the value, the greater the degree of acceleration slip, and it is necessary to lengthen the processing time in order to suppress acceleration slip. Also, the reason why the retard control is terminated even when the throttle opening degree S becomes less than a predetermined value is that when the driver is trying to prevent acceleration slip by operating the accelerator, such ignition There is no need to control the engine output depending on the timing; on the other hand, this may cause problems such as a decrease in acceleration.
When the throttle opening becomes small, it is assumed that the acceleration slip has disappeared and the control is terminated. In this case, it is not necessarily necessary to directly detect and control the throttle opening; instead, there is a need to detect and control the throttle opening, for example, the amount of accelerator depression.
The amount of intake air, etc. may also be used.

In this way, in this embodiment, the ignition timing retard control when an acceleration slip is detected is not only terminated when the throttle opening becomes less than a predetermined value, but also controlled based on the engine speed after the control is started. Since it is configured to end even when the set time has elapsed, the control time can be changed depending on the degree of acceleration slip, and if the control time is too long and the acceleration slip has subsided. To solve the problem that the engine output is suppressed and the acceleration performance is reduced, or that the acceleration slip has not subsided even after the control is finished and the control has to be executed again. I can do it. Furthermore, in this embodiment, acceleration slip is detected from the amount of change in the driving wheel speed, so the output signal from the conventional vehicle speed sensor can be used as is. There is no need to provide multiple sensors to detect speed. Furthermore, in this embodiment, when an acceleration slip is detected, the engine output is controlled by retarding the ignition timing, and the retardation amount △θ is set using the engine rotational speed Ne at the time when the acceleration slip is detected as a parameter. Since the retardation amount △θ can be set to a value corresponding to the degree of acceleration slip, similar to the setting time,
Engine output can be well controlled in response to the degree of acceleration slip. In addition to the ignition timing, the engine output control method for suppressing acceleration slip may include controlling the fuel injection amount, intake air amount, etc., for example.

〔Effect of the invention〕

As described in detail above, according to the acceleration slip prevention method of the present invention, the output reduction control of the internal combustion engine, which is executed when an acceleration slip is detected, can be performed in the intake passage of the internal combustion engine by the driver's return operation of the accelerator pedal. The system is designed to end when the opening of the throttle valve installed inside the engine falls below a predetermined opening, thereby preventing an excessive drop in output when the driver attempts to prevent acceleration slippage by operating the accelerator. As a result, it is possible to prevent acceleration slip without reducing acceleration performance.

[Brief explanation of the drawing]

1 to 8 show an embodiment of the present invention; FIG. 1 is a schematic system diagram showing a vehicle engine and its peripheral equipment to which the method of the present invention is applied;
The figure is a block diagram showing the electronic control circuit 20.
The figure is a flowchart showing acceleration slip detection processing, Figure 4 is a flowchart showing ignition timing retard control, and Figure 5 A, B, and C are each set time.
Graph representing map A with engine speed Ne used as a parameter when calculating K ₂ , No. 6
The figure is a graph showing map B using the engine speed Ne as a parameter used when determining the ignition retard amount Δθ, Fig. 7 is a time chart showing the vehicle speed pulse and the retard amount, and Fig. 8 is the ignition timing θ. It is a graph showing the relationship between P and engine output P. DESCRIPTION OF SYMBOLS 1... Engine, 11... Throttle position sensor, 18... Rotation angle sensor, 20... Electronic control circuit, 21... Vehicle speed sensor.

Claims (1)

[Scope of Claims] 1. An acceleration slip of a vehicle that starts output reduction control to reduce the output of an internal combustion engine mounted on the vehicle when the acceleration slip of the drive wheel is detected based on the drive wheel speed of the vehicle. In the prevention method, after the output reduction control is started, the opening degree of a throttle valve installed in the intake passage of the internal combustion engine becomes less than a predetermined opening degree due to the driver's return operation of the accelerator pedal. A method for preventing an acceleration slip of a vehicle, characterized in that the output reduction control is terminated when: