JPH01186436A - Drive force controller for vehicle - Google Patents

Abstract

PURPOSE:To prevent slip caused by excessive drive force at low speed gear position by prohibiting kickdown command for a speed change controller if a control characteristic map based on relation between accelerator operating amount and throttle opening is not at the uppermost position. CONSTITUTION:Means (c) operates a slip rate based on a drive wheel speed detected through means (a) and a body speed detected through means (b). Relation of the throttle opening with respect to accelerator operating amount detected through means (d) is set as a control characteristic map through means (f), and a predetermined control characteristic map is selected through means (g) according to slip rate. Furthermore, means (j) controls a throttle actuator (i) such that an actual throttle opening detected through means (e) matches to a target throttle opening set through means (h). If the selected control characteristic map is not at the uppermost position, kickdown command for a speed change controller (k) is prohibited through means 1.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a vehicle driving force control system in which a throttle valve that is mechanically disconnected from an accelerator operator is controlled to open and close in response to the operation of the accelerator operator. Regarding equipment.

(Prior Art) As a conventional vehicle driving force control device, for example, a device described in Japanese Unexamined Patent Publication No. 6C1-43133 is known.

This conventional device is an engine output control device for an automobile that controls engine output by changing the amount of fuel supplied to the engine according to the position of the accelerator pedal. Calculating means for calculating the slip rate between the tires and the road surface from the output of the rain detecting means; comparison means for comparing the calculated slip rate with a set slip rate; and a control output based on the accelerator pedal position when the calculated slip rate is large. The engine is characterized by a slip rate control means that outputs a signal that forcibly reduces the fuel supply to the engine in priority to the fuel supply to the engine.

(Problem to be Solved by the Invention) However, in such conventional vehicle driving force control devices, when the set slip rate is exceeded, the fuel supply to the engine is reduced to avoid slip; After that, control is performed to return the vehicle to the state before the slip was avoided, so there was a problem in that a similar slip would occur again after the slip was avoided.

Furthermore, when driving on roads with a low friction coefficient where drive shaft slip is likely to occur, a hunting state occurs in which the fuel supply to the engine is repeatedly decreased and increased regardless of accelerator operation, causing jerky vibrations.

In addition, when the slip rate is large, the engine driving force is forcibly controlled in priority to the throttle opening control based on the accelerator pedal position, so during slip prevention control, the correspondence between the accelerator pedal operation and the engine driving force is , and the accelerator operation feels strange.

Therefore, in order to solve these problems, the present applicant previously filed Japanese Patent Application No. 157389/1983.

However, in this prior application, when the slip rate exceeds the set slip rate, the driving force is reduced to suppress the slip, but in an automatic transmission vehicle (hereinafter referred to as an AlT vehicle), it is difficult to drive on a low μ road. When the accelerator is pressed heavily (depressing to the full throttle range), it is treated as a kickdown, and the system shifts down to a lower gear.

For this purpose, an unexpected step on the accelerator → kickdown
This operation results in a transition to a downshift, and excessive driving force is applied to the tires on the low-speed gear side, which can easily cause slippage, which is dangerous. In other words, the problem remains that this goes against the original purpose of the driving force control device, which is to control the driving force in response to the driver's unexpected accelerator operation and prevent slippage.

(Means for Solving the Problems) The present invention was made with the aim of solving the above-mentioned problems, and to achieve this purpose, the present invention adopted the following solving means.

The solution of the invention will be explained with reference to the claim correspondence diagram shown in FIG. A slip ratio calculating means C for calculating, an accelerator operation amount detecting means d for detecting the accelerator operation amount with respect to the accelerator operator, an actual throttle opening value detecting means e for detecting the actual throttle opening value of the throttle valve, and an accelerator operation amount detecting means e for detecting the actual throttle opening value of the throttle valve. a map setting means f that sets a plurality of control characteristic maps of the relationship between the throttle opening amount and the throttle opening amount; At the same time, each time the slip rate exceeds the set slip rate, a lower control characteristic map with a lower increase ratio of throttle opening relative to the accelerator operation amount is selected from the control characteristic map a predetermined time before. map selection means 9 for selecting a control characteristic map; target throttle opening value setting means for determining a target throttle opening value based on the control characteristic map selected by the map selection means 9 and the accelerator operation amount; The throttle valve opening/closing control means j outputs a control signal for making the actual throttle opening value match the target throttle opening value to the throttle actuator i, and the control characteristic map selected by the map selection means 9 is the highest level map. When the accelerator operation amount is not in the large operation amount region, the kickdown command inhibiting means β is configured to prohibit the kickdown command output to the shift control device k of the automatic transmission even if the accelerator operation amount is in a large operation amount region. It was used as a means.

(Function) If drive wheel slip occurs when driving on a road with a low friction coefficient or during acceleration driving on a road with a high friction coefficient, control is performed a predetermined period of time each time the slip rate exceeds the set slip rate. A lower control characteristic map that lowers the increase ratio of the throttle opening to the accelerator operation amount is selected from the characteristic map.
Since the throttle valve operates in the closing direction, the driving force is reduced and drive wheel slip is prevented.

In other words, this map drop control estimates that the current slip has occurred due to the control characteristic map position a predetermined time ago due to engine response delay, and uses that control characteristic map as a reference to shift to a lower map. It is possible to select the throttle valve opening degree that matches the road surface friction coefficient.

When the control characteristic map is shifted to a lower map due to map fall control as described above (that is, when it is not the highest control characteristic map), the kickdown command inhibiting means ℃ causes the accelerator operation amount to be increased. Even in the operation amount range, an output is issued to the automatic transmission's shift control device k to prohibit the kickdown command, so even if the accelerator is suddenly pressed while driving on a road with a low friction coefficient, the kickdown command will be disabled. There is no transition to a downshift, and it is possible to avoid a situation where the downshift causes excessive driving force to be applied to the tires on the low speed gear side, causing slippage.

After the map is selected as described above, the predetermined map up conditions are satisfied, but the lower control characteristic map is maintained as it is until the slip rate newly exceeds the set slip rate. Even after the drive wheel slip is avoided, the drive force does not immediately return to the level before the drive wheel slip occurred, and re-slip is prevented. Furthermore,
In response to drive wheel slip, the throttle opening degree is reduced to reduce the drive force, so hunting does not occur due to increases or decreases in the drive force. Furthermore, even during slip prevention control, the throttle opening degree is controlled in accordance with the amount of accelerator operation based on the control characteristic map selected by the map drop, so that the accelerator operation does not feel strange.

(Example) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In describing this embodiment, a driving force control device applied to a rear wheel drive vehicle will be taken as an example.

First, the configuration of the embodiment will be explained.

As shown in FIG.
, an automatic transmission 11, a propeller shaft 12, a rear differential 13, a rear drive shaft 14.15, and rear wheels 16.17.

Front wheels 18,19 are non-drive wheels.

The driving force control device A of the embodiment includes an accelerator pedal 20 that is an accelerator operator, and a throttle valve 22 provided in a throttle chamber 21 that is an intake system of the engine 10.
A control device is provided between the accelerator pedal 20 and the throttle valve 22 in place of a mechanical connection means such as an accelerator control wire, and the rear wheel rotation speed sensor 30 is used as an input sensor. It is provided with a right front wheel rotation speed sensor 31, a left front wheel rotation speed sensor 32, and an accelerator potentiometer 33, a throttle valve control circuit 34 as a calculation processing means, and a step motor 35 as a throttle actuator.

Note that the output ink face 344 of the throttle valve control circuit 34 is connected to the automatic transmission 11.
When the normally closed relay switch 37 that can prohibit kickdown commands to the A/T speed change control circuit 36 that controls the speed change is connected and the H1 signal (energized) is output from the output interface 344, the kickdown switch Even if the switch is turned ON, input of a kickdown command to the A/T shift control circuit 36 is prohibited.

The rear wheel rotation speed sensor 30 is a drive wheel speed detection means,
It is provided at the input shaft portion of the rear differential 13 and outputs a rear wheel rotation signal (vr) according to the rear wheel rotation speed VR.

Note that a light sensor, a magnetic sensor, or the like is used as the rear wheel rotation speed sensor 30, and when a pulse signal is output as the rear wheel rotation signal (vr), an input interface circuit in the throttle valve control circuit 34 is used. In 341, F.
The /V converter converts it into a voltage according to the frequency of the pulse signal, and the A/D converter converts the voltage value into a digital value, which is read into the CPU 342 and memory 343.

The right front wheel rotation speed sensor 31 and the left front wheel rotation speed sensor 3
Reference numeral 2 denotes a vehicle speed detection means, which is provided at each axle portion of the front wheels 48 and 19, and which outputs a right front wheel rotation signal (vf
r) and a left front wheel rotation signal (vfβ).

Note that signal conversion for reading the output signals from both front axle rotation speed sensors 31 and 32 by the CPU 342 of the throttle valve control circuit 34 is performed in the same manner as for the rear wheel rotation speed sensor 30.

The accelerator potentiometer 33 is a means for detecting the absolute accelerator operation amount β, is provided at the position of the accelerator pedal 20, and outputs an absolute accelerator operation amount signal (I2) corresponding to the absolute accelerator operation amount β.

Note that since the output signal from the accelerator potentiometer 33 is an analog signal based on a voltage value, it is converted into a digital value by the A/D converter of the input interface circuit 341 and read into the CPU 342 and the memory 343.

The throttle valve control circuit 34 processes input information from the input sensor and information temporarily or pre-stored in the memory 343 according to a predetermined arithmetic processing procedure, and controls the step motor 35, which is a throttle actuator.
It is an electronic circuit centered on a microcomputer that outputs a pulse control signal (c) to the CPU.The internal circuits include an input interface circuit 341, a CPU (central processing unit) 342, and a memory (RAM).

ROM) 343 and an output interface circuit 344.

As shown in FIG. 3, the memory 343 that functions as a map setting means for the throttle valve control circuit 34 includes
Region control characteristic maps #0 to #7 having eight types of upper and lower limits are set as control characteristic maps of throttle opening θ with respect to absolute accelerator operation amount β, and each map #
0 to #7 correspond to the throttle opening degree 0 that generates the maximum driving force when the road surface friction coefficient μ is shown in Table 1 below.

Table 1 The upper limit of each map #0 to #7 is the line connecting the maximum throttle opening at 3/4 of the absolute accelerator operation amount and the zero reference point, and the upper limit of the absolute accelerator operation amount of 3/4 to 4/4. The lower limit is formed by a line connecting the maximum throttle opening at the absolute accelerator operation amount 4/4 and the zero reference point.

In addition, the memory 343 of the throttle valve control circuit 34 has the following information:
As shown in FIG. 4, the relationship between the relative accelerator operation amount Δβ and the throttle opening change amount Δθ is set as a cubic curve characteristic.

The throttle valve control circuit 34 includes slip ratio calculation means, actual throttle opening detection means, map selection means, target throttle opening value setting means, and throttle valve opening/closing control means described in the claims. ing.

The actual throttle opening detection means has an internal circuit configuration that receives a 5TEP command from the CPU 342 of the throttle valve control circuit 34 to the output interface circuit 344 in the memory 343 and writes and counts the number of 5TEP in the memory 343. The actual throttle opening value of 0° is read out by the CPU at any time according to the read command from the CPU 342.
342.

Further, the map selection means includes a map up selection means and a map down selection means.

The step motor 35 is an actuator that opens and closes the throttle valve 22, and includes a rotor and a plurality of stators having excitation windings, and rotates in the forward and reverse directions by applying pulses to the excitation windings. Rotate one step at a time.

Next, the operation of the embodiment will be explained.

First, the flow of the throttle valve opening/closing control operation in the CPU 342 will be described with reference to the main routine flowchart shown in FIG. 5 and the subroutine flowchart shown in FIG.

It should be noted that the processing in the main routine of FIG.
This is a fixed-time interrupt process that is started at 0 rnsec), and the processing in the subroutine shown in FIG. Ruoci
(Output conveyor interconnected) interrupt processing.

(B) Initial Settings The main routine shown in Figure 5 starts when the engine key is inserted into the key cylinder and the ignition switch is turned from OFF to ON. A determination is made (step 100), and the process proceeds to the next initialization step 101.

In this initialization step 101, MAPFLG
Set MAPFLG=O, and set other FLGs and reference values l2oo, θ. . Clear all information such as.

(b) Slip ratio calculation processing The calculation processing of the slip ratio S between the tire and the road surface is performed in steps 102 to 107.

First, based on input signals from each rotational speed sensor 30, 31.32, the rear wheel rotational speed V R and the right front wheel rotational speed VFI are determined.
l, left front wheel rotational speed V, L are read (step 10
2), next, the front wheel rotation speed VF is calculated (step 1
03).

, and is determined by the average value.

Next, it is determined whether the rotational speed v8 of the rear wheel, which is the driving wheel, is 40 km/h or more (step 104), and vLI≧4
In the case of 0 (km/h), the process advances to step 105, and in this step 105, the slip rate S is calculated.

be.

Further, in step 104, VR<40 (km/h
), the difference in rotational speed between the front and rear wheels △V (=
VR-VF) is calculated (step 106), and a slip ratio S is set according to the calculated front and rear wheel rotational speed difference ΔV (step 107).

Therefore, the slip ratio S obtained in step 105 or step 107 is graphed as shown in FIG. 7, and this slip ratio S is changed to each set slip ratio S by the following control operations. .

This serves as a threshold for comparison with Sl and S2.

(c) Control Information Setting Process The control information setting process used in the map selection process and the accelerator work determination process, which will be described later, is performed in steps 150 to 154 and steps 251 to 255.

First, it is sampled in the process two cycles ago, and the previous absolute accelerator operation ff1I2+ is sampled in the process one cycle ago.
The accelerator pedal depression amount treated as the sum is set as the absolute accelerator operation amount β2 from the previous time (step 150). Also, it was sampled in the process one cycle ago, and this time it is an absolute 7x operation amount! . The accelerator pedal depression amount treated as the previous absolute accelerator operation amount β1 is set as the previous absolute accelerator operation amount β1 (step 151). next,
The current accelerator pedal depression amount is the current absolute accelerator operation amount β. Also, the current throttle valve opening is the actual throttle opening value θ. (step 152).

Next, the currently set absolute accelerator operation amount β. By subtracting the previous absolute accelerator operation amount, I21, from the previous absolute accelerator operation amount, the current relative accelerator operation amount ΔLo, which is the amount of change in the accelerator pedal depression amount from the processing one cycle ago, is calculated (step 153). By subtracting the previous absolute accelerator operation amount β from the operation amount β1, the previous relative accelerator operation amount ΔL, which is the amount of change in the amount of accelerator pedal depression that changed from the time of processing two cycles ago to the time of processing one cycle ago, is obtained. Calculated (Step 1
54).

In steps 251 to 255, the control characteristic map MAPFLG is stored up to a predetermined time (600 m5ec ago in this case).

The counter CTR is a counter that determines the number of times MAPFLG is looped in order to store it at a predetermined number of addresses (600msec720msec=30 in the example),
After looping 29 times between step 251 and step 253, the process proceeds to step 254 and subsequent steps. In step 252, the address (r (MAPFL
G)+CTRJ) is stored in the memory address +1. Since the past values of MAPFLG are sequentially stored in the memory at address +1 according to the loop, the value MAPFLG 600 m5ec ago, used in steps 123, 124 and steps 129, 130, which will be described later, is stored at address MAPFLG+30.

In step 254, the contents of address rMA P F L G +30J obtained in the 29th loop of step 252, that is, the value 600 m5ec before MAPFLG, are
Store in APFLG.

Note that MAPOLD is set to r 60 once per control cycle by the processing of the counter CTR shown in step 253.
The value of MAPFLG 0m5ec ago" is rewritten.

(d) Map up selection process This process is performed when the area control characteristic is located in an area control characteristic map lower than the highest area control characteristic map by the map down selection means to be described later.

The map up selection process for selecting a higher region control characteristic map with a higher increase ratio of the throttle opening θ to the absolute accelerator operation amount β from the currently selected region control characteristic map is performed in steps 110 to 119 and step 161. ~ is performed in step 163.

First, the absolute accelerator operation amount β this time. It is determined whether or not the high setting accelerator operation amount β8 or more is determined (step 1).
15). In addition, the high setting accelerator operation amount β8 in the example is as follows:
When the maximum accelerator operation amount is 1, β, which is a kick-down area boundary, is set to = 3/4.

Also, this time the absolute accelerator operation amount β. is a low setting accelerator operation amount! It is determined whether it is 5 or more (Step 2
50). Note that the low setting accelerator operation amount I2L in the embodiment is set to β, -1/4 as the boundary of the low accelerator operation region.

Then, in step 115, β. <I8 and step 25
At 0! . 〉I2. If it is determined to be L (that is, I2L
≦βo<12H), current relative accelerator operation amount ΔL
Whether o is △L0>0, that is, accelerator pedal 20
It is determined whether or not it is a depression operation (step 110), and then whether or not the slip rate S is S≦So (for example, S, = 0.1), that is, the set slip rate S. In the following, it is determined whether or not there is almost no drive wheel slip (step 111), and then the actual throttle opening value θ is determined. is θ. ≧θLIAX, that is, the throttle opening upper limit value θvAx according to the area control characteristic map where the actual throttle opening value 0° was selected last time.
It is determined (step 112) whether the MAPF
When it is determined whether the LG is MAPFLG=O, that is, whether it is one of the MA units #1 to #7 that can perform map up (step 113), and all of these map up conditions are satisfied). Proceed to step 114 and select the MAP
The FLG number (#1 to #complete) is lowered by one (step 114) and the area control characteristic map is shifted to a map one level higher. Incidentally, if even one of the map up conditions described in Step Knob 110 to Step 113 is not satisfied, the area control characteristic map selected at that time is held until all of the new map up conditions are satisfied. Ru.

Also, in step 115, β. If it is determined that ≧28, the slip ratio s −h< s≦80 (for example, S,=
O,1) (step 116).
, when S≦80, the process advances to step 117, where it is determined whether or not the timer is up. If the timer is not up, the process advances to step 11B, where the timer value is increased. The flow of step 115 → step 116 → step 117 → step 118 is repeated in this way, and if it is determined that the timer is up in step 117, MAPFLG is set to M in step 161.
It is determined whether APFLG=O, that is, whether maps #1 to #7 can be mapped, and! . ≧β8
Then, if S≦So continues for a predetermined time and all the map up conditions of MAPFLG≠0 are satisfied, step 162
Then, the MAPFLG number (#1 to #7) is lowered to the lowest level, and the area control characteristic map is shifted to one level higher. Note that step 119 and step 163 are timer clear steps, and the slip rate S is S>
When it becomes S o and when the map up control ends, the timer is cleared for the next timer value count.

In addition, the set time T for the timer up in the embodiment.

is set to 0.8 sec.

(E) Map drop selection process The map drop selection process of selecting a lower region control characteristic map with a lower increase ratio of throttle opening 0 to absolute accelerator operation amount β than the currently selected region control characteristic map is performed in step 120. ~ is carried out in step 131.

Regarding the map drop processing, the slip rate S and the first
The set value S, (for example, ', S, = 0.1) is compared,
It is determined whether S>Sl, which is the upper limit of one map drop, that is, whether drive wheel slip has occurred (
Step 120), if S>S
If LAG・A=O, FLAG−A=1 is set (step 122), and in the next step 123, M
It is determined whether the value MAPOLD (step 254) of APFLG 600m5ec ago is 7, and MAPOLD≠
At the time of 7, it is M because the condition of dropping one mapp is satisfied.
The APFLG number (#0 to #6) is incremented by 1, and the value is memorized at the MAPFLG address (step 1).
24).

Note that after one map has been dropped in step 124, it is determined in step 120 that S≦SI, and step 12
5, it is set to FLAG-A=O, and
Unless S>S is newly established, the selection process for one missing map is not performed, and the area control characteristic map selected due to one missing map in step 124 is held as is.

However, this is different if the process proceeds from step 121 to step 126 when FLAG-A=1 and satisfies the map drop condition of S>32, which will be described later.

Further, when proceeding from the step 124 to the next step 126, the slip ratio S and the second set value S2 (for example, 52=
0.3) is compared, and S, which is the one-sheet drop condition of the map
>92, that is, whether or not excessive drive wheel slip has occurred. If S>S2, the process proceeds to the next step 127, and it is determined whether FLAG-B=O. FLAG-8 if O
= 1 (step 128), and the next step 1
29 is the value MAPO 600m5ec before MAPFLG
It is determined whether LD (step 254) is 7, and M
When APOLD≠7, the condition for dropping one map (S>S2
and MAPOLD≠7), MAPO
The LD number (#0 to #6) is raised to the highest level, and the area control characteristic map is moved to a map one level lower, and then MAPOLD.
The value of is stored in MAPFLG (step 130).

Note that after one map has been dropped in step 130, it is determined in step 126 that S≦82, and step 13
1 and is set to FLAG-B=O, and
Unless S>82 is newly established, the selection process for one missing map is not performed, and the area control characteristic map selected due to one missing map in step 130 is held as is.

(v) In the area control characteristic map setting step 140, the MAP selected by the progress of the above-mentioned map up selection process and map down selection process is performed.
An area control characteristic map with the same number as the FLG number is set.

(g) Kickdown command prohibition process The kickdown command prohibition process is performed in steps 141 and 142.

First, in step 141, it is determined whether MAPFLG is 0, that is, whether it is the topmost map.
If LG=O, the process directly proceeds to step 164 and thereafter, but if MAPFLG≠0, the process proceeds to step 142. In step 142, the H1 signal is output to the relay coil 37a of the normally closed relay switch 37, and the kick Measures will be taken to prohibit down commands.

(H) Map holding process When I2o≦J2L, steps 110 to 114 of the map up selection process are bypassed in step 250, so the currently selected area control characteristic map is held as is. Become.

Furthermore, β. ≦2. Of course when! . Since ≦β□, steps 116 to 119. No signal is input to the other map up selection process in steps 161 to 163.

Also, in step 164, the current absolute accelerator operation amount β.

It is determined whether or not exceeds the low setting accelerator operation amount β, and! When o>12L, the accelerator work judgment process described later in steps 155 to 15γ is performed, and β
. When ≦β, no matter how the accelerator is operated, the process proceeds to step 158 and step 159, where the reference value β is set. . ,θ
. . In order to update the throttle opening degree θ, the throttle opening degree θ is in line with the lower limit of the selected region control characteristic map.

Note that the low setting accelerator operation HEt in the embodiment is set to IC=+/4 as the boundary of the micro accelerator operation area.

Further, when I2o≦12L, in step 250 described above, step 110 to step 1 of the map up selection process is performed.
14 is bypassed, the selected region control characteristic map is retained as is.

(S) Accelerator work discrimination process The accelerator work discrimination process uses the constant speed driving accelerator operation as the standard for determining the relative accelerator operation amount △L, so that it can be used to determine whether or not it is a constant speed driving accelerator operation. , the processing is performed in steps 155 to 159 based on the information obtained in steps 150 to 154.

First, the accelerator work judgment logic uses the previous relative accelerator operation amount ΔL1 and the current relative accelerator operation amount ΔLo to determine that the accelerator pedal 20 is being operated in the depression direction continuously from the processing two cycles ago. When an acceleration accelerator operation is determined (affirmative at step 155, affirmative at step 156), or when a deceleration accelerator operation is subsequently determined to indicate that a return operation is in progress (negative at step 155, negative in step 157),
Proceed to the next step 160.

Further, when the accelerator pedal 20 is operated to stop and is held at that position (negative in step 155, step 1
57 is affirmative), if the operation direction of the accelerator pedal 20 is switched from the depression direction to the return direction (step 155
(affirmative in step 156, negative in step 156), or vice versa (negative in step 155, affirmative in step 157), the amount of change in the amount of accelerator pedal depression changes from an increase including O to including O. It is determined that the constant speed driving accelerator operation is decreasing or changing from decreasing to increasing, and the process proceeds to step 158, where the current absolute accelerator operation amount of 2° is the accelerator operation amount reference value β. The process then proceeds to step 159 where the current actual throttle opening value θ is set. is the throttle opening reference value θ. Set as 0.

(J) Relative Accelerator Stroke Calculation Process After the above-mentioned accelerator stroke determination process is performed, the process proceeds to step 160, where the relative accelerator operation amount ΔL is calculated.

The calculation formula for this relative accelerator operation amount is △L-β0-
β. . Therefore, at the time of acceleration accelerator operation or deceleration accelerator operation, the accelerator operation change amount is calculated from the time when the constant speed traveling accelerator operation is first performed to the current absolute accelerator operation amount β0. Also, when operating the accelerator while driving at a constant speed for the first time, Δ = °C. . −℃o. Therefore, the relative accelerator operation amount ΔL becomes zero.

(l) Throttle opening change amount calculation step 170 calculates the throttle opening change amount Δ0 based on the relative accelerator operation amount ΔL obtained in step 160 and the ΔL-△θ characteristic diagram shown in FIG. be done.

(w) Target throttle opening value setting process The throttle opening reference value 0°0 and the step 170
the plate target throttle opening value θθ obtained from the throttle opening change amount Δθ calculated in step 14;
The area control characteristic map set at 0 and the current absolute accelerator operation amount β. (or the accelerator operation amount reference value β...). The throttle opening upper limit value is 0. The process of setting the target throttle opening value θ* by comparing the throttle opening lower limit value θLIIN and the throttle opening lower limit value θLIIN is performed in steps 180 to 185.

First, the plate target throttle opening value θθ is determined in step 180.
It is determined by the arithmetic expression θθ=Ooo+Δθ, which adds the throttle opening reference value e0° and the throttle opening change amount Δθ.

This plate target throttle opening value Oθ, throttle opening upper limit value θLIAX, and throttle opening lower limit value <3 &JIN
In the comparison process, it is first determined whether the plate target throttle opening value OO is greater than or equal to the throttle opening upper limit value θIJAX (step 181), and if eθ>eIJAX, the throttle opening upper limit value θIJAX is the target throttle opening value. value 0
* (step 182). Also, 0θ≦
In the case of e1jAX, it is determined whether the plate target throttle opening value Oθ is less than or equal to the throttle opening lower limit value θ2□ (step 183), and θθ<θ. In the case of 1N, the throttle opening lower limit value 0□1N is set as the target throttle opening value θ* (step 184). Also, e IJI
If N≦00≦θMAX, the plate target throttle opening value θθ is directly set as the target throttle opening value θ* (step 185).

That is, the target throttle opening value θ* is set as a value existing within the region of the selected region control characteristic map.

(W) Throttle valve opening/closing control process Once the target throttle opening value θ* is determined by the target throttle opening value setting process described above, the actual throttle opening value θ
. The process of operating the throttle valve 22 in a direction to make the value coincide with the target throttle opening value θ* is performed in steps 200 to 202 in the main routine of FIG. 5 and steps 300 to 304 in the subroutine of FIG. 6.

First, the deviation ε is from the target throttle opening value θ* to the actual throttle opening value θ. It is calculated by subtracting (Step 2
00), calculation of the motor speed of the step motor 35 based on the deviation ε obtained by this calculation, forward rotation, reverse rotation,
The determination of retention and furthermore the activation cycle of the oci interrupt routine is determined (step 201).
The oci interrupt routine (FIG. 6) is activated in accordance with the operation control details of the step motor 35 set in step 202.

Next, a flowchart of the oci interrupt routine will be described with reference to FIG.

First, it is determined whether it is time to output a holding command to maintain the state of the step motor 35 (step 300).
), when the holding command is output, the step motor 3
The stator side excitation state of No. 5 is maintained (step 301).

In addition, when the holding command is not output, the step motor 3
It is determined whether or not it is time to output a reversal command to reverse the rotation speed (step 302), and when the reversal command is output, 5TEP should be set to 5TEP-1 (step 303).
) and 5TEP-1 are output to the step motor 35 (step 301). Furthermore, when outputting a normal rotation command to rotate the step motor 35 in the normal direction, 5TE
Set P to 5TEP+1 (step 304), 5T
A pulse signal that provides EP+1 is output to the step motor 35 (step 301).

Note that this oci interrupt routine includes step 20 described above.
It is repeated within the main routine startup cycle according to the startup cycle set in step 1.

Therefore, when traveling on a low friction coefficient road and the highest control characteristic map (map #1 to #Y) other than non-zero is selected, a measure to prohibit the kickdown command is taken in step 142. By doing this, even if the accelerator pedal 20 is suddenly depressed and the kickdown switch 38 is turned on, a kickdown command is not output to the A/T shift control circuit 36, and the shift shifts to kickdown-shiftdown. It is possible to avoid a situation where excessive driving force is applied to the tires on the low speed gear side due to the downshift associated with the kickdown, resulting in slippage.

That is, this kickdown command prohibition process can achieve the original purpose of the driving force control device, which is to control the driving force in response to the driver's unexpected accelerator operation and to prevent slippage.

As explained above, in the driving force control device of the embodiment, the following effects can be obtained.

■ The β-θ control characteristic map that has been set is a region control characteristic map, and the opening/closing control of the throttle opening θ is based on the relative accelerator operation amount ΔL with respect to the absolute accelerator operation amount ρ during constant speed driving operation. Therefore, within the map range, the opening/closing control gain of the throttle valve 22 is obtained according to the accelerator work, ensuring both good vehicle acceleration and prevention of large vehicle speed changes during constant speed driving operation. can.

■ As shown in Figure 4, the △L-△θ characteristic is a cubic curve characteristic, which prevents the jerky feeling when the accelerator is pressed down even slightly, and improves the high acceleration when the accelerator is pressed down a little. Security is achieved.

■ As shown in Figure 7, the slip rate S is determined by V to the difference in rotational speed of the front and rear wheels at low vehicle speeds, so the slip rate S is determined by the difference in rotational speed of the front and rear wheels, △V.
At low vehicle speeds when the slip rate S changes, high detection accuracy and high calculation accuracy are not required, and map up control, map down control, and throttle fully closed control are performed based on the calculated value of the slip rate S due to calculation errors. Nor.

■ Absolute accelerator operation amount ρ this time. is β. In the small accelerator operation amount region of ≦f2L, the region control characteristic map selected at that time is maintained without changing the map, so that the correspondence relationship between the absolute accelerator operation amount 2 and the throttle opening θ is stable. Slight accelerator pedal 20 due to map climb
The throttle valve 20 does not open wide due to the depression operation, and large torque fluctuations in the low accelerator operation amount region can be prevented, and delicate accelerator operation is possible.

In addition, when starting the vehicle from a stopped state, ρ. ≦β.

If the control gain is made to follow the lower limit of the region control characteristic map at the time of , the control gain of the throttle opening θ relative to the absolute accelerator operation amount β can be suppressed to the minimum, and more delicate accelerator operation becomes possible.

■ Absolute accelerator operation amount this time! . is β, 〈β. The map upward control of the region control characteristic map in the intermediate accelerator operation amount region at <ρ is performed on the condition that the slip rate S satisfies S≦So when the accelerator pedal 20 is depressed. Therefore, the way the throttle valve 22 opens corresponds to the accelerator operation, causing less discomfort to the driver.
You can get a natural feeling of acceleration.

Furthermore, since the condition is added that the actual throttle opening value 0° is equal to the throttle opening upper limit value θy□, there is no sudden increase in engine driving force.

■ This time, the absolute accelerator operation NJ2° is ℃. In the map up control of the region control characteristic map in the high accelerator operation amount region at 2°C, the state where the slip rate S is S≦So is the set time T.
. Since this is performed on the condition that the acceleration continues, it is possible to obtain the high acceleration feeling intended by the driver in the high accelerator operation amount region.

Note that since the condition Ao≧°C indicating the driver's intention to accelerate is added, even if there is no direct correspondence between the absolute accelerator operation amount °C and the throttle opening degree O, the accelerator operation does not feel strange.

■ Map drop control for area control characteristic maps is performed on the condition that the slip rate S is S>S and FLAG-A=0. Even if the slip rate once becomes S≦81 after shedding, the map up condition is satisfied or the slip rate S is changed to the newly set slip rate S1 or S.
Since the lower region control characteristic map is maintained as it is until exceeding 2, even after driving wheel slip is avoided, the driving force does not immediately return to the previous driving force level that caused the driving wheel slip, and re-slip occurs. Prevented.

In addition, if the newly set slip rate S is exceeded, the map will drop further, so in response to the occurrence of drive wheel slip, the drive force is controlled only in the direction of reducing the throttle opening 0 and reducing the drive force. No hunting occurs due to changes in force, and jerky vibrations are prevented.

■ If a slip occurs in the process of opening the throttle opening based on map up control, it is estimated that the current slip occurred due to the throttle opening approximately 600m5ec ago, taking into account the engine response delay, and the opening is calculated accordingly. As a standard, map drop control is used to drop one more plate (two plates are dropped in case of excessive slip), so it is possible to obtain a throttle opening that matches the current road surface friction coefficient without causing poor acceleration or re-slip.

■ Even if an unexpected accelerator pedal operation is performed while driving on a road with a low friction coefficient, the kill-down command to the A/T shift control device 36 is prohibited unless the highest control characteristic map #0 is selected. , it is possible to prevent the occurrence of slips due to downshift operations based on kickdown commands.

Although the embodiments of the present invention have been described above in detail with reference to the drawings, the specific configuration is not limited to these embodiments, and the present invention may be modified without departing from the gist of the present invention. included.

For example, in the embodiment, an example was shown in which multiple area control characteristic maps having upper and lower limits were set, but linear control characteristic maps such as straight lines, polygonal lines, curves, etc. may also be used, or area control characteristic maps having only an upper limit may be used. But that's fine.

Furthermore, in the map drop control, the rate of change of the slip rate over time may be taken into consideration, and the number of maps to be dropped may be determined in accordance with the degree of increase in the slip rate.

Further, in the embodiment, one characteristic was shown as the ΔL-Δθ characteristic, but for example, by adding the characteristic shown in the dotted line in FIG. 0 is set, and when maps #1 to #7 are selected, Δθ may be set based on the characteristics indicated by the dotted line. In this case, the control gain of the throttle opening relative to the absolute accelerator operation amount may be set. can be adapted to the road surface conditions, and drive wheel slip is prevented.

(Effects of the Invention) As explained above, the vehicle driving force control device of the present invention can prevent re-slip, prevent jerky vibrations, and eliminate the discomfort of accelerator operation, while also taking engine response delay into consideration. The accurate map fall control that has been applied quickly suppresses drive wheel slip in accordance with the road surface friction coefficient, and has the effect of preventing poor acceleration or reoccurrence of slip after drive wheel slip prevention control.

Furthermore, when the control characteristic map is not at the highest level, the kickdown command to the automatic transmission's shift control device is prohibited even if the accelerator operation amount is large, so that unexpected acceleration when driving on a road with a low friction coefficient is prohibited. Even if a pedal depression operation is performed, there is no downshift operation based on the kickdown command, and it is possible to prevent slippage from occurring due to excessive driving force at a low speed gear position due to this downshift.

[Brief explanation of the drawing]

Fig. 1 is a diagram corresponding to claims showing a driving force control device for a vehicle according to the present invention, Fig. 2 is an overall view showing a driving force control device according to an embodiment of the present invention, and Fig. 3 is a diagram showing a throttle valve control circuit of the embodiment device. Fig. 4 is a set area control characteristic map diagram, and Fig. 4 is a relationship characteristic diagram of relative accelerator operation amount - throttle opening change amount set in the throttle valve control circuit of the embodiment device.
The figure is a flowchart showing the main routine of the control operation in the throttle valve control circuit of the embodiment, FIG. 6 is a flowchart showing the subroutine of the control operation in the throttle valve control circuit of the embodiment, and FIG. 7 is the apparatus of the embodiment. FIG. 3 is a slip ratio threshold characteristic diagram. a...-Drive wheel speed detection means b...-Vehicle speed detection means C...Slip rate calculation means d...Accelerator operation amount detection means e...Actual throttle opening value detection means f...Map Setting means 9... Map selection means h... Target throttle opening value setting means i... Throttle actuator j... Throttle valve opening/closing control means k... Speed change control device! ...Kickdown command prohibition means

Claims (1)

[Scope of Claims] 1) Slip ratio calculation means for calculating a slip ratio between the tires and the road surface based on the wheel speed obtained from the driving wheel speed detection means and the vehicle body speed obtained from the vehicle body speed detection means; An accelerator operation amount detection means for detecting the accelerator operation amount, an actual throttle opening value detection means for detecting the actual throttle opening value of the throttle valve, and a plurality of control characteristic maps that set the relationship between the throttle opening and the accelerator operation amount. When the slip rate is lower than the set slip rate, selecting a higher control characteristic map that increases the increase ratio of the throttle opening to the accelerator operation amount from the current control characteristic map; map selection means for selecting, each time the slip ratio exceeds a set slip ratio, a lower control characteristic map that has a lower increase ratio of the throttle opening relative to the accelerator operation amount than the control characteristic map of a predetermined time before; target throttle opening value setting means for determining a target throttle opening value based on the selected control characteristic map and the accelerator operation amount; and a throttle opening control signal that causes the actual throttle opening value to match the target throttle opening value. When the control characteristic map selected by the throttle valve opening/closing control means that outputs to the actuator and the map selection means is not the highest level, the control characteristic map is not output to the speed change control device of the automatic transmission even if the accelerator operation amount is in a large operation amount region. A vehicle driving force control device comprising: kickdown command inhibiting means for inhibiting a kickdown command from being output to the vehicle.