JP2717311B2 - Vehicle propulsion control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention prevents a drive wheel from slipping due to excessive drive torque on a slippery road surface such as a snowy road, thereby reducing acceleration force and stability. The present invention relates to a vehicle propulsion control device.

[Conventional technology]

Conventionally, a propulsion control device disclosed in Japanese Patent Application Laid-Open No. 62-265429 has been proposed. In this device, when the vehicle body speed is equal to or lower than a predetermined speed, the slip of the one of the left and right drive wheels that indicates the lower speed is controlled.

[Problems to be solved by the invention]

However, in the above-mentioned conventional vehicle, when starting acceleration is performed on a straddling road surface where the friction coefficient of the road surface on which the left and right driving wheels are placed is greatly different, the slip ratios of the left and right driving wheels are largely different, and the vehicle speed becomes a predetermined speed. During the following period, the slip of the one of the left and right drive wheels that shows a low speed is controlled, but when the speed exceeds a predetermined speed, the slip control of the one of the left and right drive wheels that shows a high speed is controlled. To a state in which the engine output is hardly suppressed, and suddenly changes to a state in which the engine output is greatly suppressed, which gives a sense of incongruity to the driving sensation.

The present invention has been made in view of the above problems, and performs control with emphasis on acceleration in a low vehicle speed range and performs control with emphasis on stability in a high vehicle speed region in consideration of starting acceleration on a straddling road surface. An object of the present invention is to prevent control switching from being performed suddenly.

[Means for solving the problem]

The present invention relates to a propulsion control device for a vehicle that suppresses the driving torque of an engine in order to prevent the driving wheels from slipping when the vehicle is accelerated, as shown in FIG. Wheel speed detecting means for detecting the vehicle speed, vehicle speed detecting means for detecting the vehicle speed, and the average value of the left and right driving wheel speeds is obtained by weighting with the vehicle speed. Average value calculating means for weighting the driving wheel speed when the vehicle speed is high, and controlling the slip of the driving wheels based on the average driving wheel speed obtained by the average value calculating means. Control means for controlling the driving torque of the engine as described above.

[Action]

In the present invention, when starting acceleration on a straddling road surface, even when the slip ratios of the left and right drive wheels are significantly different, the slip control of the drive wheels is performed based on the average value of the left and right drive wheel speeds, so that the vehicle body speed is low. Weight is assigned to the lower one of the left and right drive wheel speeds, and if the vehicle body speed is higher, the weight is assigned to the higher one of the left and right drive wheel speeds. Therefore, the control can satisfy both acceleration and stability regardless of the vehicle speed. In addition, since the driving wheel speed used for the control takes an intermediate value between the low speed and the high speed, the control content does not change abruptly with the switching of the control as in the related art, and the driving feeling does not feel uncomfortable.

〔Example〕

Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

In FIG. 2 showing a front engine / rear drive vehicle, the vehicle includes left and right front wheels (driven wheels) 1 and 2 and left and right rear wheels (drive wheels) 3 and 4, and the drive wheels 3 and 4 are driven by an engine 9. It is driven via a transmission, a drive shaft, and the like. Wheel speed sensors 5 to 8 for detecting wheel speeds are mounted on the respective wheels.

The electronic control circuit (ECU) 10 is a microcomputer type including a CPU, a ROM, a RAM, an I / O circuit and the like.
A brake control signal for the drive wheels 3 and 4 and a torque control signal for the engine 9 are output based on the wheel speed signal from the controller 8 and the output signal from the steering angle sensor 11.

The brake control unit (BCU) 20 controls the brake oil pressure of the drive wheels 3 and 4 by the brake control signal of the ECU 10, and the torque control unit (TCU) 50 controls the throttle opening of the engine 9 by the drive torque control signal of the ECU 10. Control.

Next, the brake control unit 20 will be described in detail with reference to FIG.

In FIG. 3, the hydraulic brakes 3a, 4a
The brake control unit 20 is provided with a pump
Pumped from reservoir 22 by 21 and accumulator 23
The hydraulic brakes 3a, 4
The brake hydraulic pressure of a is controlled to control the rotational speed of the left and right drive wheels 3 and 4.

The switching valve 24 is a two-position valve for switching between the hydraulic pressure used to drive the hydraulic brakes 3a and 4a from the hydraulic pressure from the master cylinder 60 or the hydraulic pressure from the accumulator 23. The master cylinder 60 is controlled so that the hydraulic brakes 3a and 4a can be driven by hydraulic pressure.
When the drive wheel control execution signal S1 is input from the ECU 10, the two-position valve drive circuit 25 switches to the accumulator 23 side so that the slip control can be executed by the hydraulic pressure from the accumulator 23.

Further, the left and right hydraulic control valves 31 and 32 are used to control the brake hydraulic pressures of the hydraulic brakes 3a and 4a by using high-pressure oil from the accumulator 23 transmitted through the switching valve 24 when the slip control is performed. In the position valve, the switching valve 24 is normally switched to the master cylinder 60 side.

The three-position valve drive circuits 33 and 34 are activated by the drive wheel control execution signal S1 output from the ECU 10, and thereafter control signals B _L and B _R from the ECU 10 until the drive wheel control execution signal S1 is stopped. This is for controlling the drive of the hydraulic control valves 31 and 32 according to.

The hydraulic control valves 31, 32 include a switching valve 24 and hydraulic brakes 3a, 4a.
In addition to the pressure-increasing position a that communicates with
A decompression position b that communicates the low-pressure pipe 37 that communicates with the reservoir 22 via the position valve 35 and the hydraulic brakes 3a and 4a, and a holding position c that shuts off these components and retains the brake hydraulic pressure are provided. I have.

The two-position valve 35 is normally connected to the reservoir 22 and the low-pressure line 37.
And the two-position valve drive circuit 36 is driven by the drive wheel control execution signal S1 from the ECU 10 so that the reservoir 22 communicates with the low-pressure pipe 37.

_A drive torque control device 50 that receives the torque control execution signal S2 and the torque control signal TA output from the ECU 10 and controls the drive torque from the engine 9 is configured as shown in FIG.

In FIG. 4, a throttle valve 74 for opening and closing the intake pipe 70 in conjunction with an accelerator pedal 72 is provided to the intake pipe 70 of the engine 9.
In addition, a sub-throttle valve 76 for driving torque control is provided, and the driving torque control unit 50 controls opening and closing of the sub-throttle valve 76 by a step motor 78 to control the amount of air taken into the engine 9. And control the driving torque.

The drive torque control unit 50 includes a throttle valve 74
A throttle opening sensor 80 for detecting the opening of the
Based on the detection signal from the throttle opening sensor 80, the number of steps of the step motor 78 corresponding to the opening of the throttle valve 74 is calculated as the reference number of steps.

On the other hand, the torque control execution signal S2 and the torque control signal T _A which is output from the ECU10 is input to the control step number generation circuit 84. Number of control steps generating circuit 84, based on the input torque control signal T _A, the reference step number generating circuit 82
From the reference step number as the initial value,
Is output as the number of control steps of the step motor 78.

Then, the control step number calculated by the control step number generation circuit 84 is input to the motor drive circuit 86, and drives the step motor 78 so that the step number of the step motor 78 becomes the control step number.

That is, in the drive torque control unit 50, first, the number of steps of the step motor 78
Step motor so that the reference step number calculated in
78 is driven, and the sub throttle valve 76 is closed until the opening of the throttle valve 74, then the step motor 78 driven according to the torque control signal T _A speed control step calculated in the control step number generating circuit 84 based on the Thus, by controlling the opening and closing of the sub throttle valve 76, the driving torque of the engine 9 is suppressed.

Next, the control of the ECU 10 will be described with reference to the flowcharts of FIGS.

In FIG. 5, when the process is started, first, step 10 is executed.
0 is executed, the flag F ₁ to be used for the control run, F ₂ and the brake control amount B _R, B _L, the drive torque control amount T _A, the addition value .SIGMA.B _R of each control amount, etc. to the initial value 0 .SIGMA.B _L Perform initialization to set.

In step 110, the rotational speeds V _FR , V _{FL of the} driven wheels 1, 2 and the rotational speeds V _RR , V _RL of the driven wheels 3, 4 are calculated from the detection signals from the wheel speed sensors 5 to 8, and in step 120 (1) calculates the average speed of the driven wheels 1 and 2 as shown in the expression as a vehicle speed V _V.

V _V = (V _FR + V _FL ) / 2 (1) In step 140, the reference speeds V _SB , V _ST for the brake control and the driving torque control are respectively determined by the vehicle speed V _V and the preset reference slip amount. The calculation is performed as shown by the equations (2) and (3). At this time, the reference slip amounts V _S1 and V _S2 for the brake control and the drive torque control can be set freely.

V _SB = V _V + V _S1 (2) V _ST = V _V + V _S2 (3) Next, in step 150, the left and right driven wheels 1, 2 and the driving wheels
3,4, velocity V _FR, obtaining the V _FL, V _RR, turning amount G _V from V _RL. The arithmetic expression is based on Expression (4).

G _V = | V _FR −V _FL | · i (V _FR , V _FL , V _RR , V _RL ) (4) Here, the function i is a function for detecting a turning state from each wheel speed. Further, the turning amount G _V may be determined by the steering angle signal G _V from the steering angle sensor 11. In this case, the calculation is based on the following equation.

G _V = j (C _V ) (5) Here, the function j is for obtaining the turning amount from the turning signal.

In step 160, the state of the flag F ₁ is set at the brake control execution condition is satisfied, determines whether the current during the braking control execution. Step if control is not running
The process proceeds to 170, and it is determined whether the left drive wheel speed _VRL is equal to or higher than the reference speed _VSB , that is, whether the brake control execution condition is satisfied. Here, if the condition is not satisfied, the right drive wheel is similarly determined in step 180, and if the condition is not satisfied in both the left and right drive wheels, the process proceeds to step 230.

On the other hand, left or right drive wheels when the condition is satisfied at step 170 and 180 the process proceeds to step 190, sets the brake control execution flag F ₁ proceeds to step 200. At step 200 outputs a drive wheel control execution signals S ₁ to execute the brake control in the brake control unit 20. Step 20
After 0 in the process execution, or when the flag F ₁ has been set in step 160, performs step 210, (5) calculating the left drive wheel brake control amount B _L in formula, similarly the right drive wheel control The amount _BR is calculated by the equation (6).

_{B L = K 2 (V RL} -V SB) ......... (5) B K = K 2 (V RR -V SB) ......... (6) where, K ₂ is a constant.

In step 230 calculates a weighted average wheel speed V _T of the left and right driving wheels 3,4. In a sixth diagram showing the details of the step 230, the first weighting factor f by the vehicle speed V _V at step 231
(V _V ). Specifically, as shown in FIG. 8 (a), f (V _V ) is obtained from a control map in which f (V _V ) changes according to the vehicle speed V _V. Then, obtained from a control map characteristic shown in Figure 8 the second weighting factor g (G _V) similarly by turning amount G _V at step 232 (b). Step 23
At 3, using a two-dimensional map from (V _V ) and g (G _V ),
Or using math two weights to determine the overall weighting factor P _M within 0-1.

Next, at step 234, the weighting coefficient P _M ,
A weighted average speed _VT is determined from the left and right driving wheel speeds V _RR and V _RL .

_{V T = P M · MAX (} V RR, V RL) + (1-P M) · MIN (V RR, V RL) ......... (7) However, 0 <P _M <1 here, operators MAX The operator selects the higher speed, and the operator MIN selects the lower speed.

Returning to FIG. 5, followed flag F ₂ is set at the time of the driving torque control execution condition is satisfied at step 240 is zero or not,
That is, it is determined whether or not the drive torque control is currently being executed. If the current drive torque control execution proceeds to step 250, determines the weighted average if the speed V _T becomes the reference velocity V _ST above, i.e. whether the drive torque control execution condition is satisfied. If not, step 110 in the figure
Then, the processing after step 110 is executed again. After When satisfied that sets the flag F ₂ in step 260 to 1, and outputs a torque control execution signal S ₂ to execute the drive torque control in step 270 to the drive torque control Yuchitto 50. Process of step 270 is executed, or if the flag F ₂ has been set at step 240, then execute step 280, (8) calculates the torque control amount T _A by formula, proceeds to step 110 again I do.

T _A = K ₁ · (V _T −V _ST ) (8) where K ₁ is a constant.

FIG. 7 shows a control signal output process executed as an interrupt process every predetermined time.

In Figure 7, perform the first step 300 of this process is executed, whether the flag F ₁ is set,
That is, it is determined whether the brake control is being performed. Then, if 0 the flag F ₁ is in the reset state, the control amount B _L of the right and left drive wheels 3, 4 and proceeds to step 310, the B _R 0
, And in the subsequent step 320, the added value of each of the control amounts B _L and B _R Σ
B _L, the .SIGMA.B _R is set to 0. Also, following step 330, stops the output of the control execution signal S _1, shifts to the drive wheel control signal B _L, the output of B _R is stopped in the next step 340, the process proceeds to step 400.

On the other hand, when the flag F ₁ in step 300 it is determined that the set state, i.e., conditions for executing the brake control is satisfied, if it is a braking control performed, step
350 proceeds to, and outputs the brake control unit 20 controls the amount B _L of the right and left drive wheels 3, 4 calculated by the control amount calculating process, the B _R as a control signal. Moreover, the subsequent step 360, the output by the drive wheel control amount B _L, adds the B _R current drive wheel control amount adding value .SIGMA.B _L, the .SIGMA.B _R to update its value. The drive wheel control amount adding value .SIGMA.B _L, .SIGMA.B _R is 0 and the lower limit value. And
In step 370, it is determined whether the updated drive wheel control amount adding value .SIGMA.B _L becomes 0, the process proceeds to step 380 if .SIGMA.B _L = 0, the process proceeds to step 400 otherwise . In step 380, the updated drive wheel control amount adding value .SIGMA.B _R is determined whether it is 0, .SIGMA.B _R =
If 0 After resetting the flag F ₁ proceeds to the next step 390, the process proceeds to step 400, control proceeds to step 400 otherwise. Note that the processing of steps 370 and 380 is processing for determining the end of the brake control based on whether or not the added values ΣB _L and ΣB _L of the respective drive wheel control amounts B _L and B _R have become 0. there are, then executes step 390 when determining the end of the brake control by resetting the flag F _1, so that the brake control is stopped in the processing of step 330 and step 340 at the next processing run.

Next, in step 400, whether the flag F ₂ is set, that is, the drive torque control determines whether running. Then, if the flag F ₂ is reset, the operation proceeds to step 410 to set the control amount T _A of the driving torque to zero.

In step 430, it stops the output of the torque control execution signal S _2, shifts to stop the output of the control signal T _A in the next to 440, the process ends.

On the other hand, when the flag F ₂ in step 400 it is determined that the set state, that is, execution conditions of the drive torque control is satisfied, if the current driving torque control is being executed, the process proceeds to step 450 Te, and outputs the drive torque control unit 50 a control amount T _a of the drive torque calculated by the control amount calculating process as the control signal. And the following step 470
In, the drive torque control end signal SE from the drive torque control unit 50 determines whether the set state, the flag F ₂ goes to next be 480 if the drive torque control end signal SE is in the set state After the reset, the process is temporarily terminated, otherwise, the process is terminated. In the processing of step 470, if it is determined the completion of the torque control, by resetting the flag F ₂ executes step 480, step 430 and step 440 at the next processing run
The drive torque control is stopped in the processing of (1).

In the above structure, when the vehicle starts or when accelerated running, its the V _RL or V _RR becomes the reference velocity V _SB above, is output drive wheel control execution signals S ₁ from the ECU10 to slip occurs in the driving wheels 3,4 Thus, the brake control is performed by the brake control unit 20, and the speed of the drive wheel in which the slip has occurred is suppressed.

The running condition of the vehicle (vehicle speed, turning amount) weighting factor P _M is calculated by the drive wheel 3 on the basis of the weighting factors P _M,
Weighted average speed V _T of 4 is computed.

When the weighted average speed V _T is the reference speed V _ST above, is executed drive torque control of the engine 9 by the drive wheel control execution signal S ₂ is output drive torque control unit 50 from the ECU 10, the drive wheel which also Speed is controlled.

In this control, when the calculation result of the torque control amount T _A by the equation (8) is positive, the auxiliary throttle valve 76 is driven in the closing direction to increase the reduction amount of the driving torque, and when the result is negative, the auxiliary throttle valve 76 is reversed. controlled so that the average velocity V _T weighted left and right driving wheels 3 and 4 by decreasing the reduction amount of drive torque to drive the throttle valve 76 in the opening direction to the reference velocity V _ST.

Next, a description will be given weighting factors P _M. As shown in FIG. 8 (a), the first weighting f (V _V) to the first speed V ₁ was a constant value, the first velocity V ₁ ~ to the second speed V ₂ is gradually changed, second speed V ₂ or is a fixed value, increasing the weight when the vehicle speed V _V is large as a whole, when the vehicle speed V _V is small based on the tendency to reduce the weight, depending on the vehicle speed V _V The determined weight f (V _V ) is determined.

Similarly, as shown in FIG. 8 (b), the second weight g
(G _V ) is a constant value up to the first turning amount G ₁ , and the first turning amount G ₁ to
Until the second turning amount G ₂ slowly changes, the second turning amount G ₂ or is a fixed value, when the larger weight greater turning amount G _V is as a whole, when turning amount G _V is small Based on the tendency to reduce the weight, a weight g (G _V ) corresponding to the turning amount G _V is determined. Above two weights f _(V V), it superimposes the g (G _V), to determine the weighting factors P _M as shown in the following equation.

P _M = h (f, g) The weight coefficient P _M obtained from the two weights f and g basically has the characteristics shown in FIGS. 8 (a) and (b). Within a predetermined range of, for example, 0.2, 0.3, 0.4, 0.5, 0.
It changes slowly while taking an intermediate value like 6,0.7.

By determining in this way the weighting factors P _M, at the time of high speed running, or turning, a high select tendency with weight on the larger side of the large slip of impact speed high side of the drive wheel, i.e. on the stability Become. On the other hand, when the vehicle is traveling straight and at low speed, the low-selection tendency is weighted on the side where the driving speed is low, that is, on the side where the slip has a large influence on the acceleration and the small slip.

Based on this weighting coefficient P _M, by performing the drive torque control described above, during straight low-speed running has excellent acceleration, at high speeds and swing becomes possible to control with excellent stability and acceleration-oriented, Since the tendency of emphasizing stability gradually shifts according to the running state, the control characteristics do not change suddenly.

〔The invention's effect〕

As described above, according to the present invention, when starting and accelerating on a straddling road surface, even if the slip ratios of the left and right drive wheels are significantly different, both acceleration and stability are satisfied regardless of the vehicle speed. Control. In addition, the control content does not suddenly change with the switching of the control as in the related art, and the driving sensation does not feel uncomfortable.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the overall configuration of the present invention, FIG. 2 is a schematic diagram showing a first embodiment of the present invention, FIG. 3 is a schematic diagram showing the brake control unit of FIG. 1, and FIG. FIGS. 5 to 7 are schematic diagrams showing the driving torque control unit, FIGS. 5 to 7 are flowcharts for explaining the operation, and FIG. 8 is a characteristic diagram for explaining the operation. 3,4 ... drive wheel, 5,6,11 ... wheel speed sensor, steering angle sensor, 7,8 ... drive wheel speed sensor, 9 as running state detecting means
…… Engine, 10 …… Electronic control circuit, 76 …… Sub throttle valve.

Continuation of the front page (72) Inventor Kiyotaka Ise 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (56) References JP-A-2-176127 (JP, A) JP-A-62-265430 (JP, A) JP-A-2-151538 (JP, A) JP-A-62-265429 (JP, A) JP-A-2-70563 (JP, A) JP-A-58-16948 (JP, A)

Claims (1)

(57) [Claims] 1. A propulsion control device for a vehicle for suppressing the driving torque of an engine in order to prevent the driving wheels from slipping when the vehicle is accelerating, comprising: a driving wheel speed detecting a rotation speed of left and right driving wheels of the vehicle. Detecting means, a vehicle speed detecting means for detecting a vehicle speed, an average value of the left and right driving wheel speeds is obtained by weighting the vehicle speed, and if the vehicle speed is low, the average of the left and right driving wheel speeds is weighted by the lower one of the left and right driving wheel speeds. An average value calculating means that weights the higher one of the left and right driving wheel speeds when the speed is higher, and a driving torque of the engine based on the average driving wheel speed obtained by the average value calculating means so as to suppress the slip of the driving wheels. A vehicle propulsion control device, comprising: control means for controlling a vehicle.