JPS6099757A - Slip preventing device for vehicle - Google Patents

Abstract

PURPOSE:To aim at enhancing the running stability and accelerating capability of a vehicle, by controlling engine torque in accordance with a road-surface frictional coefficient which is estimated based upon the condition of trailing wheels, a tracting wheel speed and a trailing wheel speed. CONSTITUTION:A compare circuit 9 receives a tracting wheel speed signal from a tracting wheel speed sensor 1 and a trailing wheel speed signal from a trailing wheel speed sensor 2. Further, the trailing wheel speed signal is differentiated to compute the trailing wheel acceleration from which a road-surface discriminating circuit 8 estimates the road-surface frictional coefficient mu that is delivered to the comparator circuit 9. The comparator circuit 9 compares the tracting wheel speed with the trailing wheel speed to judge occurrence of a slip when the tracting wheel speed is predetermined number (k) times higher than the trailing wheel speed, and therefore torque control device 11 controls engine torque through a control signal generating circuit 10. Further, the value of K is set to be small as the estimated frictional coefficient mu is small, but is set to be large as the mu is large.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a slip prevention device for a vehicle, and in particular, prevents the vehicle from running stably by suppressing excessive slip that occurs when starting and accelerating. The present invention relates to a slip prevention device for a vehicle that can secure and improve acceleration performance.

Prior Art] Conventionally, various devices have been proposed that suppress the engine torque of a vehicle based on the driving wheel speed and the driven wheel speed when the vehicle accelerates or starts, thereby suppressing the slip of the driving wheels. For example, a slip prevention device detects the speed difference between the driving wheel speed and the driven wheel speed, and when this speed difference reaches a predetermined amount, delays the ignition signal by a predetermined time from the original ignition timing to suppress the engine torque; Or driving wheel speed and driven wheel 3! ! An example of this is a slip prevention device that operates a link mechanism to open and close a throttle valve to suppress engine torque when the ratio of i degrees reaches a predetermined value.

However, the driving conditions of vehicles vary widely, and the characteristics of the road surface itself (high μ roads such as dry concrete,
intermediate μ roads represented by wet asphal 1~, low μ roads represented by waterways), tire wear level, type, and weather conditions.
The coefficient of friction μ between the road surface and the tire varies depending on the condition of the road surface, etc., and it has been extremely difficult to perform good slip control.

In other words, since the predetermined value is a constant value regardless of the road surface condition, it may impair running stability on a road surface where the road surface friction coefficient μ is low and is prone to slipping, or deteriorate acceleration or drivability on a road surface where μ is high and difficult to slip. There was a problem.

[Object of the Invention] The present invention has been made in view of the above points, and its purpose is to estimate the road surface friction coefficient μ and control the engine torque in accordance with μ. An object of the present invention is to provide a slip prevention device for a vehicle that can improve running stability and acceleration.

[Configuration 1 of the Invention The configuration of the present invention to achieve the above object includes a driving wheel speed detection means a for detecting the driving wheel speed, and a driven wheel speed detection means for detecting the driven wheel speed. μ estimating means C that estimates the road surface friction coefficient μ based on the road surface friction coefficient μ, a control means d that outputs a control signal according to the road surface friction coefficient μ, the driving wheel speed, and the driven wheel speed, and control from the control means d. The gist of the present invention is a slip prevention device for a vehicle characterized by comprising a torque control means e for controlling the torque of a vehicle engine 1 based on a signal.

[Example] The present invention will be described below with reference to examples and drawings.

FIG. 2 shows the structure of the slip prevention device of the first embodiment using an analog circuit. In the figure, 1 is a driving wheel speed sensor that detects the driving wheel speed, 2 is a driven wheel speed sensor that detects the driven wheel speed, and 3.4 is a waveform shaping circuit that shapes each signal from the speed sensor 1.2 into a rectangular wave. , 5.6 is a D'/A conversion circuit that converts a digital signal corresponding to the number of waveform-shaped rectangular waves into an analog signal, and 7 is a D'/A conversion circuit that differentiates the driven wheel speed detected by the D/A conversion circuit 6. 8 is a road surface determination circuit that estimates a road surface vi friction coefficient μ from the driven wheel acceleration and determines the road surface condition when a comparison circuit 9 (to be described later) determines that a slip has occurred. , 9 is a comparison circuit that compares the driving wheel speed and the driven wheel speed to determine whether or not there is a slip state; 10 is a control signal generation circuit that outputs a signal to suppress engine torque when slip is determined; and 11 is a control signal generation circuit that outputs a signal to suppress engine torque. This is a 1-lux control 11 device that suppresses engine 1-herk when a slip occurs based on a signal from a control signal generation circuit 10.

Incidentally, the driving wheel speed sensor 1 detects the driven wheel speed l! as the driving wheel speed detecting means a. [The sensor 1J2 is connected to the driven wheel speed detection means, the acceleration calculation circuit 7 and the road surface discrimination circuit 8 are connected to the μ estimation means C,
The waveform shaping circuit 3.4, the D/A conversion circuit 5.6, the comparison circuit 9, and the control signal generation circuit 10 correspond to the control means d, and the torque control device @11 corresponds to the torque control means e.

Next, the operation of the above-mentioned analog circuit will be explained in detail. First, the voltage waveform output from the driving wheel speed sensor 1 is shaped into a rectangular wave by the waveform shaping circuit 3 and input to the D/A conversion circuit 5, and from the D/A conversion circuit 5, the voltage waveform corresponding to the driving wheel speed is output. The voltage is output and input to a comparison circuit 9 that performs slip determination. Similarly, the output of the driven wheel speed sensor 2 is shaped into a rectangular wave by the waveform shaping circuit 4.
The A conversion circuit 6 converts the voltage into a voltage corresponding to the driven wheel speed. The acceleration calculation circuit 7 calculates the driven wheel acceleration by differentiating the driven wheel speed obtained from the D/Δ variable ground circuit 6.
It is output to the road surface discrimination circuit 8. When the comparison circuit 9 starts determining that a slip has occurred, the road surface discrimination circuit 8
The road surface friction coefficient μ is estimated from the driven wheel acceleration, the road surface condition is determined, and the result is transmitted to the comparison circuit 9. In the comparison circuit 9, the D/A
The driving wheel speed obtained from the variable circuit 5.6 is compared with the driven wheel speed, and the driving wheel speed is determined to be a predetermined times the driven wheel speed (K times, K-
1.1 to 2.0), it is determined that there is a slip, and the torque of the engine 1 is suppressed by the torque control bag @11 via the control signal generation circuit 10.

In this embodiment, the value of K in the comparator circuit 9 is switched based on a signal from the road surface discrimination circuit 8. That is, when the road surface friction coefficient μ is small (for example, μ<Q, 3), prioritize safe driving and reduce the value of K (for example, = 1', 1).
When μ is large (for example, μ≧0.3), set the value of K to be large (for example, =1.4).
．． ) to prioritize acceleration and drivability.

FIG. 3 shows the results of control 1 when the road surface friction coefficient μ is large. In the figure, the solid line represents the driven wheel speed, the dotted line represents the slip determination level, and the solid line waveform represents the driving wheel speed. When driving at a constant speed, the driving wheel speed and the driven wheel speed are equal. When acceleration begins at time ta, the driven wheel speed increases approximately linearly.

Also, the driving wheel speed increases more rapidly than the driven wheel speed, and the time tb
After time tb reaches the slip judgment level, the drive wheel speed becomes greater than the slip judgment level, but the analog circuit suppresses the re-engine torque, so the drive wheel speed decreases. Then, at time tc, the driving wheel speed becomes equal to the slip judgment level, and after time tc, the driving wheel speed becomes smaller than the slip judgment level, but since the vehicle is accelerating, the driving wheel speed increases and returns to the slip judgment level. is equal to Thereafter, the waveform will be similar, and the driving wheel speed will be maintained near the slip determination level.

FIG. 4 shows the control results when the road surface friction coefficient μ is small. Compared to Fig. 3, the slope of the driven wheel speed is gentler because the road friction force is smaller, and the slip judgment level is set lower, so the driving wheel speed is lower than when the road friction coefficient μ is large. The waveform has a gentle slope.

Due to the configuration of this embodiment as detailed above, when the vehicle is in an accelerating state and the road surface friction coefficient μ is large, the value of K is set large, that is, the slip judgment level is set high. Since the engine torque is set, the engine torque is not over-controlled with respect to the road friction force, and sufficient acceleration and drivability are ensured. Also, since the road surface friction coefficient μ is large, there is no problem with running stability.

On the other hand, when the vehicle is in an accelerating state and the road surface friction coefficient μ is small, contrary to the above-mentioned 1=, the value of K is set small, that is, the slip judgment is 1, and /bell is set low. Therefore, the engine torque is sufficiently suppressed, slippage is kept low, and running stability is good.

Next, a method for calculating the road surface friction coefficient μ will be explained. In general, the road surface friction coefficient μ depends on the road surface condition and slip rate.
), but normally the slip rate reaches the maximum value or a value close to the maximum value at about 10% to 20%. At that time, the force transmitted to the road surface is μ×Wr (Wr is the load of the driving wheels), and this force is balanced by the sum n1 of steady running resistance such as rolling resistance, air resistance, and acceleration resistance of the vehicle.

Incidentally, the slip rate during acceleration is defined as in the following equation.

S=(ωR-V)xl 00/ (ωR)(%)...
(1) However, ■ is the speed of the vehicle, ω is the angular velocity of the tire, and R is the radius of the tire.

At the time of acceleration slip, the steady running resistance is relatively small and can be ignored, and it is considered that μ×Wr is consumed in accelerating the vehicle. Acceleration resistance is W・α/g when slipping
(W is the total vehicle weight, 9 is the gravitational acceleration, α is the vehicle acceleration)
Therefore, the road surface friction coefficient μ can be approximated by W·α/Wr−0. Here, W and Wr differ depending on the number of people on board, etc., but it can be considered that their influence on the value of μ is small and constant. Therefore, if the vehicle acceleration α is equalized, the road surface friction coefficient μ is equalized. Furthermore, in this example,
Since the driven wheel speed is used as the vehicle speed, the vehicle acceleration α uses the driven wheel acceleration obtained by differentiating the driven wheel speed.

In this embodiment, the value of K in the comparator circuit 9 is switched in two stages depending on the value of the road surface friction coefficient μ, but it may be switched in three or more stages to improve control accuracy.

Next, as a second embodiment, a slip prevention device will be described in which a microcomputer is used to cut fuel while switching the number of cylinders according to the value of the road surface friction coefficient μ.

FIG. 5 shows the 1 m limit of the anti-slip device of the second embodiment. In the figure, 15 is a driving wheel speed sensor that detects the driving wheel speed, 20 is a driven wheel speed sensor that detects the driven wheel speed, 30 is a first crank angle sensor υ that outputs a pulse every 720° CA, and 40 is a first crank angle sensor υ that outputs a pulse every 720° CA. 1 A pulse with a phase shift of 360'CA relative to the output of the crank angle sensor 30 is generated at 720'CA.
50 is a microcomputer; 50 is a microcomputer; 60 is a slip control device that performs fuel cupping when slip occurs; and 60 is a fuel supply device that supplies appropriate fuel according to the operating state of the engine. . Furthermore, in the slip control device 50, 51 is a central processing unit (hereinafter simply referred to as CPU) that performs calculations such as slip determination, 52G is a counter that counts the pulse width of the speed sensor 15, 20, and 53 is a speed sensor. Input the signals of Lee 15, 20 and crank angle sensor 30, 40
51 is a random access memory (hereinafter referred to as
It is simply called RAM. ), 55 is a read-only memory (hereinafter simply R) that stores calculation programs and control data.
It's called OM. ), 56 is an I10 boat that outputs a control signal to the fuel supply device 6o.

In addition, the driving wheel speed sensor 15 has a driving wheel speed detecting means a,
The driven wheel speed sensor 2o has a first driven wheel speed detection means.
Crank angle sensor 30. Second crank angle sensor 40. The slip control device 5o corresponds to μ estimation means C and control means d, and the fuel supply device 6o corresponds to torque control means e.

Next, the operation of this embodiment will be explained. In FIG. 5, the slip control device 5o determines that the drive wheels are in a slip state based on the signals from the speed sensors 15 and 20, calculates the road surface friction coefficient μ, and when μ is small, the fuel cylinder is activated like a normal fuel cut. In order to perform the fuel injection, a fuel injection signal is output to the fuel supply device 60. On the other hand, when the road surface friction coefficient μ is large, the first crank angle sensor 30, for example,
Fuel is cut from the pulse generation of the second crank angle sensor 40 to the pulse generation of the second crank angle sensor 40 (01 mode), and from the pulse generation of the second crank angle sensor 40 to the pulse generation of the first crank angle sensor 30 (G2 mode and J ) performs normal fuel injection and outputs a C1 intermittent fuel cut signal to the fuel supply device 60 in order to cut fuel only in half of all cylinders.

The detailed operation of the slip control device 50 using a microcomputer will be explained with reference to the flowchart of FIG. First, when the process is started, the driving wheel speed VW is calculated from the output of the speed sensor 15 in step 100, the driven wheel speed VV is calculated from the output of the speed sensor 20 in step 101, and further, in step 102. Driven wheel speed VV
Let K (Q (K = 1.1 to 2.0)L) and slip judgment level v d, and in step 103, drive wheel speed VW and slip judgment level VT are compared to determine whether or not the drive wheels are slipping. If it is determined that VW≦V-T, it is determined that there is no slip, and the process advances to step 109, where the fuel cut signal is reset and normal fuel is supplied to the fuel supply device 6o via the I10 port 56. command and return to step 1°O.

On the other hand, if it is determined in step 103 that VW>VT holds true and there is a slip, the driven wheel speed Vv is differentiated in step 104, and the driven wheel acceleration VV corresponding to the vehicle acceleration is calculated, and in step 105 The road friction coefficient μ is μ
-W-vv/wr・(] (W is the total vehicle weight, Wr is the driving wheel load, g is the gravitational acceleration), and Step 1
In step 06, the magnitude of the road surface friction coefficient μ is determined based on a certain predetermined value μ0 (for example, μo−0,3>), and if μ is determined to be small at μ<μ0, the fuel The cut signal is sent to the cell 1-56, and the fuel supply device 6o is instructed to perform a fuel cut to the metal cylinder via the I10 port 1-56, and the process returns to step 100.

On the other hand, if it is determined in step 106 that μ≧μ0 and the road surface friction coefficient μ is large, the process advances to step 108 to check whether the aforementioned G1 mode is the G2 mode, and if it is the G1 mode, the process advances to step 107. So Mooto no Jtsu 1-,
If the mode is G2 mode instead of G1 mode, normal fuel supply is instructed to the fuel supply device 60 via the I10 boat 56 in step 109, and the process returns to step 1oo. As a result, the G1 mode and G2 mode are switched every engine revolution, so the fuel is cut every other revolution, i.e.
A half cylinder fuel cut is performed.

In the conventional method, the fuel cut method was the same regardless of the road surface. Therefore, when fuel is cut for the golden cylinders, the drive wheel speed drops significantly on roads with a large road surface friction coefficient μ, leading to deterioration of drivability and acceleration. When a fuel cut was performed, slips could not be sufficiently suppressed on a road surface with a small road surface friction coefficient μ. However, by configuring this embodiment as described above, as shown in FIG.
As a result, the engine torque is greatly suppressed and slip is sufficiently suppressed.On the other hand, as shown in Figure 3, on road surfaces with a large road surface friction coefficient μ, fuel is cut only in some cylinders, so the reduction in engine torque is small and the drop in driving wheel speed is reduced. It not only has good drivability and acceleration, but also can sufficiently suppress slippage.

Next, a third embodiment will be explained. This embodiment has almost the same configuration as the second embodiment, and a steering angle determination program and a reference road surface friction coefficient μ0 changing program are added to the control program.

In the figure, steps 300 to 305 and steps 308 to 311 are the same as those in the second embodiment, so their explanations are omitted, and steps 306 and 30
7 will be explained.

First, when the process is started, steps 300 to 305 are performed. In the following step 306, it is determined whether the steering angle O of the steering wheel is larger than a predetermined steering fI'lθ0, in other words, whether the vehicle changes its direction of travel or changes its course. If it is determined to be rYIEsJ, the process advances to step 307, and if it is determined to be rNOJ, the process advances to step 308.

In step 307, the reference road surface friction coefficient .mu.O is set to .mu.m larger than .mu.0, and the subsequent steps 308 to 311 are performed, and then the process advances to step 300, where the same processing is performed.

By configuring this embodiment as described above, when the vehicle changes its traveling direction or course, for example, when traveling down a long downhill slope with many curves that is prone to slipping, the road surface friction is reduced. Since the coefficient .mu.0 is increased and the slip determination level is made stricter, the "resin 1" torque is further suppressed and slips can be further suppressed.

Incidentally, regardless of the embodiment, the number of cylinders to which the fuel supply is cut off may be changed by appropriately controlling the fuel injection instruction signal, and instead of cutting off the fuel supply, the number of cylinders to which the fuel supply is cut may be changed by cutting the ignition or The engine torque may be suppressed by opening and closing the valve, making the air-fuel ratio leaner, suppressing the amount of intake air, etc., and the engine torque may be controlled not by the engine torque, but by the gear position of the transmission and the slippage of the clutch. The transmission torque of the drive wheels may be suppressed, and if a slip condition is determined, an anti-slip device is activated and a warning buzzer or warning lamp is displayed to notify that the feeling of pressing the accelerator pedal is different from normal driving conditions. The driver may be notified, and the invention is not limited to this embodiment as long as it does not go beyond the gist of the present invention.

[Effects of the Invention] The present invention is configured to estimate the road surface friction coefficient μ and control the engine torque according to the value of μ.

Therefore, regardless of μ, the driving wheel speed is controlled with high precision, slippage is suppressed, and good running stability can be obtained.

There is also the effect that acceleration and drivability can be ensured.

11. II that suppresses the unpleasant slip noise that occurs? There are also first-order effects.

[Brief explanation of drawings]

Fig. 1 is a basic configuration diagram of the present invention, Fig. 2 is an abrog circuit showing the basic configuration of the first embodiment, and Fig. 3 is a graph showing how the driving wheel speed is controlled on a high μ road. , Figure 4 shows low μ
Graph showing how the driving wheel speed is controlled on the road, No. 5
The figure shows a control circuit showing the basic configuration of the second embodiment, FIG. 6 is a flowchart of the control program of the second embodiment, and FIG.
The figures each represent a flowchart of the control program of the third embodiment. 1.15... Drive wheel 3I degree sensor 2.20... Driven wheel speed sensor 7... Acceleration calculation circuit 8... Road surface discrimination circuit 9... Comparison circuit 30... First crank angle sensor 50... Slip control capacity 60... Manufactured by Fuel Supply System Tetsu Mari

Claims (1)

[Scope of Claims] 1. Drive wheel speed detection means for detecting the drive wheel speed, driven wheel speed detection means for detecting the driven wheel speed, and μ estimation means for estimating the road surface friction coefficient μ based on the driven wheel speed. and a control means for outputting a control signal according to the road surface friction coefficient μ, the driving wheel speed and the driven wheel speed, and a torque control means for controlling the engine torque of the vehicle based on the control signal from the control means. A vehicle slip prevention device comprising: 2. The vehicle slip prevention device according to claim 1, wherein the μ estimating means calculates the driven wheel acceleration from the driven wheel speed and estimates the road surface friction coefficient μ based on the driven wheel acceleration. 3. The vehicle slip prevention device according to claim 1 or 2, wherein the control means is a control circuit that changes the slip determination level according to the value of the road surface llJ friction coefficient μ. 4. The vehicle according to claim 1, 2, or 3, wherein the control means is a control circuit that changes the number of cylinders to which fuel supply is cut off according to the value of the road surface friction coefficient μ. Anti-slip device for use.