JPH0765522B2 - Vehicle skid control device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a skid control device for a vehicle, and more particularly to a skid device that can immediately stop a wheel spin if it occurs after starting.

[Prior art]

High-output engines tend to be mounted on recent vehicles, and along with this, it is important to efficiently transmit the driving force from the engine to the road surface. Of course, vehicles are also used on slippery roads such as snowy roads, icy roads and mud roads, but when driving on such a road surface, the driving force applied to the drive wheels is the grip force, that is, between the road surface and the drive wheels. The friction resistance of the vehicle may be greater than the friction resistance of the vehicle, and the so-called skid, in which the drive wheels spin idle, is prone to occur, and it is difficult to start the vehicle on such a slippery road surface. Sometimes the vehicle may go off course.

Therefore, conventionally, in order to solve such a problem of the reduction of the glyph force, improvement in terms of hardware such as making the vehicle four-wheel drive type, mounting high-performance tires, and improving roll rigidity has been studied.

Further, as a means that can solve the problem of skid from the aspect of software, there is a skid control device described in Japanese Patent Laid-Open No. 59-202963, which is a left or right driving wheel of a vehicle. The rotational speed of the driven wheels is detected to obtain the rotational speed difference between the two wheels, and when the rotational speed difference exceeds a predetermined value, either the accelerator or the clutch is controlled to prevent the occurrence of wheel spin. It was something that was done. However, in this conventional device,
It only controls either the accelerator or the clitch so that the driving force is reduced. For example, since there is no concrete control target value for reducing the driving force, the control accuracy is low, and in the end, the skid in this conventional device is low. The effect of preventing the occurrence was not so great.

[Object of the Invention]

The present invention has been made in such a conventional situation,
When wheel spin occurs after starting the vehicle, the drive force of the vehicle can be controlled to a drive force that does not cause spin depending on the traveling road surface, that is, according to the grip force on the road surface. An object of the present invention is to provide a skid control device for a vehicle that can be stopped immediately and surely.

[Structure of Invention]

The present inventor has found the following points as a result of studying the change characteristics of the rotational speeds of the driving wheels and the driven wheels during acceleration after starting. Here, FIG. 5 shows the characteristics between the friction coefficient μ of the tire and thus the grip force and the slip ratio S. The tire friction coefficient μ initially increases with an increase in the slip ratio S during start acceleration (region P ₁ ), The limit slip ratio S _L
At the critical friction coefficient μ _L and decreases thereafter (region
P ₁ ), reaching the wheel spin state. FIG. 4 shows changes in the rotational speeds of the driving wheels and the driven wheels (curves A and B). As is clear from the figure, at the point a, the rotational speeds of the driving wheels rapidly increase, that is, Wheel spin is occurring. The present inventor considered that the slip ratio corresponding to the rotational speed at the point a corresponds to the maximum grip force on the traveling road surface, and thus to the limit friction coefficient. That is, the slip ratio S at this point a is the tire friction coefficient μ shown in FIG.
-It represents the limit slip ratio S _L in the slip ratio S characteristic, and therefore, if the slip ratio at the point a is grasped, this is considered to be a target value in skid control.

Therefore, the present invention provides a skid control device for a vehicle, as shown in the functional block diagram of FIG.
The rotation sensors 8 and 9 detect the rotation speeds of the driving wheels and driven wheels, and the slip ratio calculation unit 10 calculates the slip ratio S from the outputs of the first and second rotation sensors 8 and 9, and the slip ratio setting unit 11
But calculates the rate of change alpha of the slip ratio S, to set the slip ratio S ₀ to the last calculated time rate of change of the slip ratio S alpha is larger than the predetermined value alpha ₀ as the target slip ratio S _T,
The actuator 1 in which the acceleration control unit 12 is the driving force control unit
4, 15 are configured to control the slip ratio to the target value S _T.

〔Example〕

 Embodiments of the present invention will be described below with reference to the drawings.

2 and 3 show an embodiment of the present invention, in which 1 is a front-wheel drive type vehicle, 2 is its body, 3 is an engine, and a throttle valve 3b is attached to its intake passage 3a. ing. Reference numeral 4 is a clutch for connecting or disconnecting the output of the engine 3 to the transmission 5, and 6 is a front wheel as a driving wheel, which is driven by the output of the engine 3 via the clutch 4 and the transmission 5.
Reference numeral 7 is a rear wheel as a driven wheel, which is driven through the vehicle body 2 by the forward movement of the automobile 1 due to the rotation of the front wheel 6. Further, 8 is a front wheel sensor as a first rotation sensor for detecting the rotation speed of the front wheel 6, 9 is a rear wheel sensor as a second rotation sensor for detecting the rotation speed of the rear wheel 7, 21 and 22 are accelerator pedal positions, An accelerator and a clutch sensor that detect the clutch pedal position.

Reference numeral 15 denotes a clutch actuator as a driving force control unit, which is for driving the clutch 4 to connect and disconnect, that is, for controlling the position of the clutch 4, and is completely connected from a completely disengaged position through a break and a meet point. The clutch 4 is moved to the position.

FIG. 3 shows a throttle actuator 14 which is another drive force control unit, 16 is a hydraulic cylinder, and a piston rod 16a of the hydraulic cylinder is provided with a drive wire 16b for the intake passage.
The throttle valve 3b is connected to the throttle valve 3b of 3a, and the retracted position of the piston rod 16a is detected by a throttle valve sensor 16c which is a feedback positioner. Reference numeral 17 denotes a servo valve provided in a hydraulic pressure supply passage 20 that communicates the cylinder 16 with the hydraulic pump 18, which serves to control the switching of the hydraulic oil supply to the hydraulic cylinder 16, and 19 A reducing valve for reducing the discharge pressure of the hydraulic pump 18 to a predetermined value.

Reference numeral 25 is a control unit composed of an interface 26, a CPU 27 and a memory 28.
Reads the input information to the unit 25,
For outputting a control signal from the CPU, and the memory 28 stores a skid control program for the CPU 27 and the like.

Then, the CPU 27 calculates the slip rate S by the equation (1) and the slip rate change rate α by the equation (2) at predetermined measurement timings, for example, every 0.02 seconds, and the change rate α becomes a predetermined value α ₀ or more. when, the slip ratio S ₀ at the time of the previous measurement timing set as the target slip ratio S _T, the throttle, and controls the clutch actuator 14, 15 to the target slip ratio S _T as the target value .

Where Vdn and Vrn are the rotation speeds of the front wheels 6 and the rear wheels 7 at the current measurement timing, Sn and S ₀ are the slip ratios at the current and previous measurement timings, and K is the measurement timing interval, for example, 0.02 seconds. is there.

Further, in the present embodiment, the CPU 27 in the above-mentioned configuration realizes the functions of the slip ratio calculation unit 10, the slip ratio setting unit 11 and the acceleration control unit 12 of FIG.

Next, the function and effect will be described.

Here, FIG. 6 shows a flowchart of the skid control by the CPU 27, and the control of the present embodiment is started at the start of the engine 3, for example, and is executed at every predetermined measurement timing (0.02 seconds). When this skid control program starts, the CPU 27 determines whether or not it is the measurement timing (step 51), and at the measurement timing, it is detected in steps 52 to 55 whether or not the start is completed. That is, the CPU 27
Determines whether or not the vehicle is traveling based on the output signals from the front and rear wheel sensors 8 and 9 (step 52). When the vehicle is not traveling, the clutch 4 is turned off, the clutch 4 is then engaged, and the vehicle speed is further increased. When the idling vehicle speed is exceeded, completion of the starting operation is detected (steps 53 to 55). When the vehicle is traveling in step 52, the throttle valve angle corresponding to the accelerator pedal position is calculated (step 65).

When the start operation is completed, the target slip ratio S _T is set in steps 56-61. That is, the CPU 27 reads the outputs Vdn, Vrn of the front wheel and rear wheel sensors 8, 9 and calculates the slip ratio S by the above equation (1) (step 56), and the current slip ratio register section of the slip ratio change rate calculation register. Sn and the previous slip ratio register S ₀ are updated with the current slip ratio S and the current slip ratio register value Sn, respectively (step 57), the slip ratio change rate α is calculated by the above equation (2), and the change rate α is calculated.
Is determined as positive or negative (steps 58 and 59). This rate of change α
Is positive, it is determined whether or not the change rate α is larger than a predetermined change rate α ₀ (step 60). When it is larger, the target value is set as the target slip rate S _T of the slip rate S ₀ at the previous measurement timing. Store in the register (step 61). If α is negative in steps 59 and 60 and α is smaller than α ₀ , the process proceeds to step 65.

Finally, in steps 62 to 64, the CPU 27 controls the acceleration so that the vehicle slip ratio becomes the target slip ratio S _T. That is, a target throttle valve opening and a target clutch position for realizing the target slip ratio S _T are calculated (step 62), and the current throttle valve opening and clutch position and the calculated opening and position are calculated. By comparison, control signals for the throttle valve servo valve 17 and a clutch servo valve (not shown) are created, and the control signals are generated for the throttle actuator 14,
Output to clutch actuator 15 (steps 63, 6
Four).

Then the servo valve of the above throttle actuator 14
17 is switched in a predetermined direction by the servo valve control signal, whereby the drive cylinder 16 expands and contracts and the throttle valve
3b is rotated in the opening direction or the closing direction, and the position of the clutch 4 is controlled.
It is driven by the driving force that can obtain S _T , and the wheel spin is stopped.

As described above, in this embodiment, when the starting operation is completed, the change rate α of the slip rate S is calculated, and the change rate α is set to the predetermined value α _0.
When it becomes larger, that is, when the wheel spin state occurs, the slip ratio S ₀ at the previous measurement timing,
In other words, the actuator 14,1 is set with the target value of the slip ratio with the maximum grip force and no wheel spin.
Since 5 is controlled, the driving force to the front wheels 6 can be controlled to a driving force according to the grip force on the road surface, and the vehicle can travel smoothly. Further, at this time, since the acceleration control is performed with the specific control target value, the control accuracy can be improved.

Although the acceleration control is performed by controlling both the throttle valve opening and the clutch position in the above embodiment, this acceleration control may be performed by either the throttle valve opening or the clutch position. You may

〔The invention's effect〕

As described above, according to the skid control device for a vehicle according to the present invention, when the rate of change of the slip ratio becomes equal to or more than a predetermined value after the start operation is completed, the slip ratio at the previous measurement timing is used as the target value for acceleration. Since the control is performed, it is possible to obtain the driving force corresponding to the gripping force of the traveling road surface immediately after the start of traveling, to immediately and surely stop the wheel spin, and to have the effect of stably traveling.

[Brief description of drawings]

FIG. 1 is a functional block diagram showing the configuration of the present invention, FIG. 2 is a configuration diagram of a skid control device for a vehicle according to an embodiment of the present invention, FIG. 3 is a configuration diagram of its throttle actuator portion, and FIGS. FIG. 6 is for explaining the operation, FIG. 4 is a characteristic diagram showing changes in the rotational speed of the wheels with the passage of time, FIG. 5 is a tire friction coefficient μ-slip rate S characteristic diagram, FIG. FIG. 6 is a flowchart showing the contents of the skid control of the CPU. 1 ... automobile (vehicle), 3 ... engine, 4 ... clutch, 6 ... front wheel (driving wheel), 7 ... rear wheel (driven wheel),
8 ... Front wheel sensor (first rotation sensor), 9 ... Rear wheel sensor (second rotation sensor), 10 ... Slip ratio calculator, 11 ...
… Slip rate setting unit, 12 …… Acceleration control unit, 14,15 ……
Throttle, clutch actuator (driving force controller).

Claims (1)

[Claims] 1. A first rotation sensor for detecting a rotation speed of a drive wheel of a vehicle, a second rotation sensor for detecting a rotation speed of a driven wheel, a detection result of the first rotation sensor and a second rotation sensor. A slip ratio calculation unit that calculates a slip ratio based on the detection result, a slip ratio setting unit that sets a target slip ratio based on the calculation result of the slip ratio calculation unit, and a target set by the slip ratio setting unit The slip ratio setting unit includes an acceleration control unit that controls acceleration based on a slip ratio, and the slip ratio setting unit includes a slip ratio storing unit that stores the slip ratio calculated by the slip ratio calculating unit. The slip rate change rate is calculated from the stored previously obtained slip rate and the slip rate calculated this time in the slip rate calculation unit, and the calculated slip rate change rate is A skid control device for a vehicle, wherein the slip ratio calculated last time is set as a target slip ratio when a predetermined value or more is reached.