JPS62265429A - Slip controlling method for driving wheel of vehicle - Google Patents

Abstract

PURPOSE:To effectively use the driving force from an engine at the time of low speed traveling by controlling the slippage of the driving wheel which indicates the lower speed of detected right and left driving wheels when the speed of vehicle is lower than a defined speed. CONSTITUTION:The output signals of speed sensors 21-24 for detecting the speeds of right and left driving wheels 11, 12 and right and left driven wheels 13, 14 at the time of operating a vehicle are taken in an ECU35. In this ECU35, the excessive slip of the right and left driving wheels 11, 12 is detected based on the speed of the right and left driven wheels at the time of the accelerating operation of the vehicle and, when excessive slip is detected, a fuel injection valve 36 is controlled to restrict the slippage of the driving wheels 11, 12. In this case, vehicle speed is detected based on the speeds of the right and left driven wheels 13, 14 and, when the vehicle speed is lower than a defined speed, the slippage of the driving wheel 11 or 12 which indicates the lower speed of the right and left driving wheels 11, 12 is controlled. Thereby, the driving force of an engine at the time of low speed traveling can be effectively used.

Description

[Detailed description of the invention]

(Technical field) The present invention is a vehicle driving system! PI] II+! The present invention relates to a slip control method, and particularly relates to a method of controlling slip of drive wheels when a vehicle starts or accelerates. (Technical background of the invention and its problems) In general, when a vehicle starts or accelerates, the driving force of the driving wheels is the friction force between the tires and the road surface [friction coefficient between the tires and the road m1 x vehicle V4 weight h]

If the load on the drive wheels (wheel load) is exceeded, the drive! l! IJ @ slips though. The slip ratio λ representing the degree of slip is determined by the following equation (1), where Vw is the circumferential speed of the driving wheels and V is the speed of the vehicle (the circumferential speed of the driven shaft). λ= (Vw-V)/Vw ・= (1) This slip ratio λ determines the frictional force between the tires and the road surface (i.e., the friction force of the driving wheels!
The limit value of the driving force changes as shown in FIG. 6 and reaches a predetermined value λ. The frictional force of the lever is at its maximum. Furthermore, the frictional force between the tires and the road surface is the frictional force in the vehicle's traveling direction (vertical direction), but the lateral frictional force (lateral force) increases as the slip ratio λ increases, as shown by the dotted line in the figure. descend. Based on this point, the longitudinal friction force between the tires and the road surface is maximized to maximize vehicle drive efficiency, and the reduction in the lateral friction force between the tires and the road surface is suppressed as much as possible to prevent the vehicle from skidding. In order to prevent this, the slip rate λ is detected and set to a predetermined value λ. There is a way to control the value close to . More specifically, in this method, for example, the predetermined value λ is determined according to the vehicle speed V with respect to the slip ratio λ. A lower limit value λ and an upper limit value λ2 of a predetermined range including the driving wheel speed Vw and vehicle speed V are set.
The driving wheel torque control device controls the torque of the driving wheels according to the value of the slip ratio λ obtained from I try to control the feedback within the system. In such a conventional method, a high select method is used in which the speed of the left and right driving wheels, which exhibits a higher value, is selected and used as the driving wheel speed Vw for calculating the slip ratio λ based on the above formula (1). was adopted. According to this method, excessive slip of one wheel is prevented, so the difference in driving force between the left and right drive wheels does not become large, and as a result, especially in the front 4+! In a drive-type vehicle, there is no problem such as the steering wheel becoming loose due to the difference in the driving force between the left and right model J wheels, and the steering stability of the vehicle is improved. By the way, when power is transmitted from the engine to the left and right drive wheels via a differential gear (hereinafter referred to as the differential), even if one of the drive wheels is slipping excessively, a certain 11i is applied to the differential. : Due to the presence of vibrational force, even if one wheel is slipping excessively, the differential I'd I? , f is transmitted to the other drive wheel that is not slipping excessively. Furthermore, if one drive wheel that is slipping excessively is accelerating the vehicle, the reaction force against the drive force required for acceleration by that drive wheel is transmitted to the other drive wheel via the differential. be done. However, when the high select method is adopted, there is a problem in that these driving forces are not effectively utilized, and the driving force may be insufficient, especially when the vehicle is running at a low speed. (Object of the Invention) The present invention has been made in view of the above circumstances, and it is possible to effectively utilize the driving force from the engine when the vehicle is running at low speed, and to improve the efficiency of the vehicle when the vehicle is running at medium to high speed. An object of the present invention is to provide a slip control method for drive wheels of a vehicle, which improves steering stability. (Structure of the Invention) In order to achieve the above object, the present invention detects excessive slip of the driving wheels during acceleration operation of a vehicle, and when the excessive slip is detected, immediately reduces the driving force of the driving wheels. of the vehicle to limit the slip of the drive wheels! In the drive wheel slip control method, the speed of the vehicle is detected, the speeds of the left and right drive wheels of the vehicle are respectively detected, and when the speed of the vehicle is below a predetermined speed, the lower of the detected left and right drive wheels is detected. A method for controlling the slip of a drive wheel of a vehicle is provided, which comprises controlling the slip of the drive wheel that is indicating the speed. (Example) Hereinafter, an example of the present invention will be described with reference to the drawings. Figure 1 shows the vehicle of the present invention! ψDrive wheel slip control force θ;
The vehicle 1 is of a front wheel drive type, for example, and the front wheels 1.1.12 are drive wheels driven by an engine 31 via a clutch, a transmission 16, and a differential gear L5 (not shown). The rear wheels 13 and 14 are driven wheels. (As will be clear from the following explanation, the present invention can be applied to rear-transport drive vehicles in exactly the same way.) The first drive wheel 1
The drive wheel speed sensors 21, 22 and driven wheel speed sensors 23, 24 are installed on the drive wheel speed sensors 21, 22 and driven wheel speed sensors 23, 24, respectively. The driving wheel speed ωFL + ωFR is detected, and the left and right driven wheel speeds ω6 and ωRR are detected by the driven wheel speed sensors 23 and 24, and these detection signals are E
It is input to CU35. First of all, ECU35. Average value of driven wheel speed ω6 ωR (ω tag + ω, eh)/2
Find the vehicle speed V by Then, the vehicle speed V is a predetermined speed V
MI1. When the speed is lower than 1 (for example, 5 km/h), the slip of the drive wheel with the lower speed is controlled (low selection). That is, the lower one of the driving wheel speeds ωFL+ωFk is set to the value ω corresponding to the driving wheel speed Vw in the above equation (1). Thereby, the driving force from the engine is effectively utilized when the vehicle is running at low speed. Further, when the vehicle speed (2) is higher than the predetermined speed V M IN , the slip of the higher speed drive wheel is controlled (high select). That is, the higher of the driving wheel speeds ωFL+ωFR is set as the ωF value corresponding to the driving wheel speed Vw in the above equation (1). This maintains the steering stability of the vehicle when the vehicle is running at medium to high speeds. In both the low select and high select controls described above, the speed of the driven wheel on the same side as the driving wheel that is the subject of control among the driven wheel speeds ω and ω is calculated using the above equation (1). The ωR value is used instead of the vehicle speed V. This can reduce the apparent slip when the vehicle turns. Therefore, the slip rate λ is determined by the following equation (2). −f □ □ ... (2) N = ωF Furthermore, E CU 35 is the change in slip ratio λ fj: (
Differential value) Find the support. Incidentally, in digital control, this amount of change is substituted by the difference for each calculation processing cycle. Further, a clutch (not shown) and a transmission 16 interposed between the engine 31 and the drive wheels 11 and 12 are each equipped with a sensor (not shown), and the clutch signals from these sensors and the transmission The signal is input to the ECU 35. When the ECU 35 determines that the clutch is engaged based on the clutch signal, the ECU 35 controls the engine 31 using a fuel supply control device (described later) to drive the engine 31,
12 to control the slip ratio λ (see equation (2) above) of the drive shafts 1111!11.12. More specifically, the ECU 35 sets the predetermined value λ shown in FIG. 6 as a slip ratio control reference value determined for the slip ratio λ according to the vehicle speed ω6 and the gear ratio detected by the transmission signal. The lower limit value λ and the upper limit value λ2 of a predetermined range including The first and second slip ratio change amount control reference values Σ1 and (i, > e,) are set according to the control delay until the start of the slip ratio control and the reference value for slip ratio control. Speed ωF (ω, L or ωFk) and lower limit value λ
The predetermined speed value 7 shaku and the upper limit value λ determined corresponding to
2, the difference between the predetermined speed value V and the change M in the slip ratio, and the first and second reference values. The fuel supply control device is controlled according to the difference from E2. That is, the ECU 35 controls the fuel supply control device according to the following control laws (i) to (iii). (i) ωp ) V @□ and Friend〉support, then control 1, for example, cut fuel in the direction that λ becomes smaller (Pre-21 +
11 control). (11) If ωF>V, control in the direction of decreasing λ. For example, cut fuel (prevent excessive slip rate). (iii) E〉For friend 2, control in the direction of decreasing the support,
For example, cut fuel (prevent excessive slip rate speed). In this case, the predetermined speed values ■3□ and ■2□ are calculated by, for example, the following equations (3) and (4). ■Eh, = yo・ω Conger C10−... (3) ωR VRz=に2・ωR102+ (4) ωR Also, as another example, when the vehicle speed is high, VR4 and VR□ It may be calculated using the following equations (5) and (6), and set to 11 (when the speed is low, a constant value V C1g ■C2. ,2
= 2・ω, +C2...(6) Here, ni, ni...
C, , C2, D, and D2 are coefficients and constants for setting ■, 1, and VB2 to values corresponding to the lower limit value λ and upper limit value λ2, respectively. Furthermore, the reference value for controlling the amount of change in slip ratio). and E2 are calculated using the following equations (7) and (8). Huh, = r1・ω8+1? □ ・ (7) L=
rz' (LIR+F2 ・-(8) Here, r + r corresponds to the vehicle speed ωk, and
It is a coefficient for calculating the value and the binary value, and it is F engineering. 1 and 2 are constants for correcting the support value and the support value in accordance with the gear ratio of the transmission, respectively. The reason why the slip rate speed (amount of change in the slip rate) is used in addition to the slip rate λ to control the slip rate λ as in the control laws (i) and (iii) above is because
If the slip ratio λ is within a predetermined range, and the slip ratio speed is large even if it is within ~λ2, the slip ratio λ is within the predetermined range λ.
Since it is predicted that a+I+ will deviate from □~λ2,
This is to improve the responsiveness of the control of the slip ratio λ by performing preliminary 11tl+ control in response to this. FIG. 2 is an overall configuration diagram of the fuel supply control device. Reference numeral 31 indicates, for example, a four-cylinder internal combustion engine, and an intake pipe 32 is connected to the engine 31. A throttle body 33 is provided in the middle of the intake pipe 32, and a throttle valve 33' is provided inside. A throttle valve opening (θTl+) sensor 34 is connected to the throttle valve 33' and converts the valve opening of the throttle valve 33' into an electrical signal, which is sent to an electronic control unit (rEcUJ hereinafter) 3.
It is set to be sent to 5th. A fuel injection valve 3G is provided in the intake pipe 32 between the engine 31 and the throttle body 33 for each cylinder, slightly upstream of the intake valve (not shown) of each cylinder. The fuel injection valve 36 is connected to a fuel pump (not shown) and is connected to a fuel pump (not shown).
It is electrically connected to the CU 35, and the opening time of the fuel injection valve 36 is controlled by a signal from the ECU 35. On the other hand, the throttle valve 33' of the throttle body 33
An absolute pressure (PDA) sensor 38 is connected downstream via a pipe 37.
An absolute pressure signal converted into an electrical signal by the absolute pressure sensor 38 is sent to the ECU 35. The engine 31 body has an engine cooling water temperature sensor (r
Tw sensor 39) is provided.
consists of a thermistor, etc., and is inserted into the circumferential wall of the engine cylinder filled with cooling water, and the detected water temperature signal is sent to the ECU 35.
supply to. An engine rotation speed sensor (hereinafter referred to as "rNe sensor") 40 is attached around the camshaft or crankshaft (not shown) of the engine, and the Ne sensor 40
is a crank angular position signal (hereinafter r This TDC signal is output by the ECU.
Sent to 35th. A three-way catalyst 42 is disposed in the exhaust pipe 41 of the engine 31 to purify HC, CO, and NOx components in the exhaust gas. An 02 sensor 43 is inserted into the exhaust pipe 41 on the upstream side of the three-way catalyst 42, and this sensor 43 detects the oxygen concentration in the exhaust gas and supplies an 02 concentration signal to the ECU 35. The drive wheel speed sensor 21゜22
, the driven wheel speed sensors 23 and 24, and other parameter sensors 44, such as a sensor that detects the engagement state of the clutch and a sensor that detects the gear ratio of the transmission 16, are connected. The detected value signal is supplied to the ECU 35. The ECU 35 includes various sensors (including the driving wheel speed sensors 21 and 22, the driven wheel speed sensors 23 and 24, the Vη clutch sensor, and the sensor of the transmission 16).
An input circuit having functions such as shaping the input signal waveform from the input signal, correcting the voltage level to a predetermined level, and converting an analog signal value into a digital signal value: 35a, central processing circuit (hereinafter referred to as rcPU) 35b, It is composed of a storage means 35c for storing various arithmetic programs executed by the CPU 35b, the results of the play, etc., an output circuit 35c1 for supplying a drive signal to the fuel injection valve 36, and the like. C1) U35b calculates the fuel injection time T o of the fuel injection valve 36 given by the following equation based on the engine parameter signals from the various sensors described above supplied via the input circuit 35a every time the TDC signal is input. Calculate uT. ToUr=Ti XK, +2- (9) Here, Ti
Is this the basis of the injection time of the fuel injection valve 36? <1! This value is determined according to the engine rotational speed Ne and the intake pipe absolute pressure PICA. K□ and 2 are the starting characteristics according to the engine operating state based on the engine parameter signals from each of the above-mentioned sensors, respectively;
These are correction coefficients and correction variables that are calculated based on a predetermined calculation formula so that various characteristics such as exhaust gas characteristics, fuel efficiency characteristics, and additive characteristics are optimized. The CPU 35b calculates the fuel injection time T obtained as described above.
A drive signal for opening the fuel injection valve 36 based on the output signal is supplied to the fuel injection valve 36 via the output circuit 35d. FIG. 3 is a flowchart of a slip control program for the drive wheels of a vehicle according to the present invention, which is executed by the CPU 35b at every predetermined timer period. First, in step 1, the speeds ωF and ωFR of the left and right drives @ 11 and 12, and the speeds ω of the left and right driven wheels 13 and 14,
Load ω. Next, in step 2, vehicle speed V = (ω tag +
Calculate ω■)/2. In the next step 3, it is determined whether the vehicle speed V is lower than the lower limit value VMIN, and if the answer is affirmative (Yes), the vehicle is at an extremely low speed, so the step is to set the extremely low speed flag FL to 1. 4) Proceed to the first step 5. In step 5, left and right! ψJ! ll1life11.
The speed difference between 12 is 1ωF and -ωF shaku! is larger than a predetermined value Δω6, and if the answer is H', constant (Yes), only one 1ψ driving wheel is in a state of excessive emptying, so to prevent this. Set the fuel cup 1-flag flag C to 1 and end the two programs. If the determination result in step 5 is negative (NO), the fuel is cut!・Reset the flag FC to O Step 6
), proceed to step 9 described below. Also, if the determination result in step 3 is negative (NO),
The extremely low speed flag FL is reset to 0 (step 7), and the process proceeds to step 9 and subsequent steps. In step 9, it is determined which of the left and right driving wheel speeds ωF and ωFi+ is larger (for example, whether ωFit>ωFL or not). The result of the determination in step 9 is stored in the high flag FF (step 10 or 11).
). The drive wheel high flag F is set to 1 when the right drive wheel speed ωF is higher, and to 0 when the left drive wheel speed ωF is higher. In the next step 12, it is determined whether or not the extremely low speed flag FL is set to 1, and the answer is affirmative (Yes).
), the lower speed of the driving wheel and the speed of the driven wheel on the same side as the lower speed driving wheel are used to calculate the slip ratio λ (low selection). The torque of the driving wheels is controlled (steps 13 to 17). That is, in step 13,
It is determined whether the drive wheel high flag F is set to 1 (right), and if the answer is affirmative (Yes). As the ωF value and the ω value, the left driving wheel speed ωFL and the left driven wheel speed ω, which are on the side opposite to the side indicated by the flag F, are set, respectively (step 14.15). Also, if the answer to step 13 is negative (No),
The right driving wheel speed ωF large and the right driven wheel speed (JR
ll respectively (step 16.17). On the other hand, if the determination result in step 12 is negative (No), the higher speed of the driving wheels and the speed of the driven wheel on the same side as the first driving wheel with the higher speed are used to calculate the slip ratio λ.
(high select) so that the torque of the drive wheel with the greater slip is controlled (steps 18 to 22). That is, in step 18, the drive wheel high flag FF is set to 1.
If the answer is 11i constant (Yes), the right drive wheel speed ωF2 and the right drive wheel speed ωF2 indicated by the flag 17F as the ω value and Set each driven wheel speed ωR11 (Step 1
9.20). Further, if the answer to step 18 is negative (NO), the left driving wheel speed ωFL and the left driven wheel speed ωRL indicated by the flag FF are set as the ωF value and the ω2 value, respectively (step 21.22 ). After that, in step 23, the slip rate λr]=(ω
F-ωR) /ωF is calculated. Next, in step 24, the slip rate λ0 during the current loop and λn− during the previous loop are calculated.
, the slip rate differential value λn is determined from the difference between the . In steps 25, 26 and 27, the above-described excessive slip rate speed prevention control process is performed. That is, it is determined whether or not the slitting rate change n is larger than the reference value E2=r2・ω, +F'2 (step 25). If the answer is affirmative (Yes), the fuel cut flag FC is set to 1. (step 26), and ends this program. If the answer to step 25 is negative (NO), the flag FC is reset to O (step 27), and the process proceeds to the next step 28. In steps 28, 29 and 30, the slip prediction control process described above is performed. That is, it is determined whether or not the slip rate change n is greater than the reference value (r, ω, F1) (step 28), and if the answer is affirmative (Yes), the slip ratio is subject to control. The speed ω of the driving wheel is a predetermined speed value V,
Determine whether it is larger than 1 = ki・ω, + C engineering + D engineering/ω (Step 29). If the answer is also affirmative (Yes), set the fuel cut flag FC to 1 (
Step 30), end this program. Note that the determination in step 29 is based on steps 290, 291, and 29 in FIG.
2 and 293 may be replaced. In this case, the predetermined speed value ■*x=kt' ω2+C1 is the reference value Vc1(
For example, it is determined whether or not ω is larger than 5klII/h).
Step 2! Set the predetermined speed value V scale, = □・ω scale + C□ as the REF value! ]l), if negative (No), a reference value VcL is set as the ω1tEF value (step 292), and then the speed ωF of the drive wheel to be controlled is ω. It is determined whether the value is larger than the F value (step 293). If the determination result in either step 28 or 29 is negative (No), the process proceeds to the first step 31. In steps 31, 32 and 33, the excessive slip rate prevention control process described in 1TI is performed. In other words, the speed ωF of the drive wheel to be controlled becomes 2·ω to the predetermined speed value VR2=
+C2+D, determine whether it is larger than /ω6 (step 31), and if the answer is affirmative (Yes), set the fuel cut flag FC to 1 (step 32)
End one program. Note that the determination in step 31 may be replaced by the same determination as in steps 290, 291, 292, and 293 in FIG. In this case, kl
, C, . It goes without saying that the constants of Vcm are replaced by the constants of kzHczHVc2. If the answer to step 31 is negative (NO), reset the flag FC to O (
Step 33), end this program. On the other hand, FIG. 4 is a flow chart of the fuel supply control program, which is executed by the CPU 35b every time the TDC signal is generated. This program is executed with priority over the program shown in FIG.
It is executed by interrupting the process of the program shown in the figure. First, in step 41, it is determined whether the fuel cut flag FC, which is set and reset by the program shown in FIG. 3, is set to 1. If the answer to this determination is affirmative (Yes), it means that the 1/2 cut should be executed, so the program is immediately terminated. If the answer to step 41 is negative (No),
The valve opening time T OLI T of the fuel injection valve is calculated (step 41), a valve opening driving signal is outputted according to the Tout value (step 42), and the present program 1 ends. (Effects of the Invention) As described in detail above, the slip control method for the drive wheels of a vehicle according to the present invention detects excessive slip of the drive wheels during acceleration operation of the vehicle, and when the excess slip is detected, the drive wheels In a slip control method for a drive wheel of a vehicle in which the slip of the drive wheel 11Q is limited by attenuating the drive force of the drive wheel, the speed of the vehicle is detected, the speeds of the left and right drive wheels of the vehicle are detected, respectively;
When the speed of the vehicle is below a predetermined speed, the slip of the detected left and right drive wheels, which is showing a lower speed, is controlled, so that when the vehicle is running at a low speed, the engine The driving force from the vehicle can be effectively utilized, and the steering stability of the vehicle can be improved when the vehicle is running at medium and high speeds.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a vehicle to which the ``JA#J wheel slip control method of the present invention is applied; Fig. 2 is a block diagram of a fuel supply control device which is a single drive torque control device; Fig. 3; is E
Flowcharts 1 to 1 of the slip control program executed in the CU 35. FIG. 4 is a flowchart of the fuel supply control program, FIG. 5 is a flowchart showing another example of the determination in step 29 of FIG. 3, and FIG. 6 is a characteristic diagram of the frictional force between the tire and the road surface with respect to the slip rate. . 11, 12... Drive wheel, 13.14... Driven wheel, 1
5...Clutch, 16...Transmission, 21.22...
- Drive wheel speed sensor, 23° 24... Driven wheel speed sensor, 31... Engine, 35... ECU (drive wheel torque control device).

Claims (1)

[Claims] 1. A vehicle that detects excessive slip of a driving wheel during acceleration operation of the vehicle, and when the excessive slip is detected, reduces the driving force of the driving wheel to limit the slip of the driving wheel. In the drive wheel slip control method, the speed of the vehicle is detected,
The speeds of the left and right drive wheels of the vehicle are respectively detected, and when the speed of the vehicle is below a predetermined speed, the slip of the drive wheel exhibiting a lower speed among the detected left and right drive wheels is controlled. A slip control method for driving wheels of a vehicle, characterized by: 2. A slip control method for driving wheels of a vehicle according to claim 1, wherein the power transmission device of the vehicle includes a differential gear between left and right driving wheels.