JP2522783B2 - Vehicle drive force control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a driving force control for a vehicle in which a throttle valve mechanically disconnected from an accelerator operator is controlled to open and close according to the operation of the accelerator operator. Related to the device.

(Prior Art) As a conventional vehicle driving force control device, for example, a device described in JP-A-60-43133 is known.

This conventional device is a vehicle engine output control device that controls the engine output by changing the fuel supply amount to the engine according to the accelerator pedal position, in a drive wheel rotation speed detection means, a non-drive wheel rotation speed detection means, Calculating means for calculating the slip ratio between the tire and the road surface from the outputs of both detecting means, comparing means for comparing the calculated slip ratio and the set slip ratio, and a control output based on the accelerator pedal position when the calculated slip ratio is large. It was characterized in that it was provided with a slip ratio control means for outputting a signal for giving priority to forcibly reducing the fuel supply to the engine.

(Problems to be Solved by the Invention) However, in such a conventional vehicle drive force control device, when the slip ratio of the drive wheels exceeds the set slip ratio, the current throttle opening is controlled in the closing direction. However, when the slip is converged, the throttle is opened up to the throttle opening corresponding to the preset accelerator operation amount, so that there is a problem that a re-slip occurs while trying to return to the throttle opening that caused the slip. Cause

In order to solve the above problem, the applicant changes the map to a lower map in which the increase ratio of the throttle closing degree to the accelerator operation amount is reduced every time the drive wheel slip ratio exceeds the set slip ratio, and the driving force to prevent re-slip. A control device has been proposed (Japanese Patent Application No. 61-157389).

In addition, in Japanese Patent Application No. 61-162248, in order to satisfy the driver's expectation of acceleration in the high accelerator region, if the driver continues to the upper level map for a certain period of time without further pressing the accelerator, a high acceleration feeling intended by the driver is obtained. The resulting drive force control device is proposed.

However, in the device of Japanese Patent Application No. 61-162248, the predetermined time is uniquely determined. Therefore, if the predetermined time is set to be short, the map position will change due to the engine response characteristic with a response delay. However, the control wheel shifts to a higher control characteristic map before it is judged whether or not it is optimal, and the recurrence of the drive wheel slip easily occurs.

Also, if the predetermined time is set to a long time commensurate with the engine response characteristics, it takes time for the throttle to return when the road friction coefficient changes from a low friction coefficient road to a high friction coefficient road, resulting in insufficient acceleration feeling. I will invite you.

That is, it is not possible to achieve both the prevention of re-slip and the feeling of acceleration at the fixed predetermined time.

(Means for Solving Problems) The present invention has been made for the purpose of solving the above problems, and in order to achieve this object, the present invention uses the following solving means.

The solution means of the present invention will be described with reference to the claim correspondence diagram shown in FIG. 1. The slip ratio between the tire and the road surface is calculated by the wheel speed obtained from the driving wheel speed detection means a and the vehicle body speed obtained from the vehicle body detection means b. Slip ratio calculating means c, accelerator operation amount detecting means d for detecting an accelerator operation amount with respect to an accelerator operator, actual throttle opening value detecting means e for detecting an actual throttle opening value at a throttle valve, and accelerator operation amount A map setting means f for setting a plurality of throttle opening degrees as a control characteristic map, and when the slip ratio calculated by the calculation exceeds the set slip ratio, the throttle opening for the accelerator operation amount is calculated from the current control characteristic map. After selecting the lower control characteristic map with a lower rate of increase, and selecting the lower control characteristic map , Until the slip ratio newly exceeds the set slip ratio, the control characteristic map is held as it is, and the state in which the accelerator operation amount is equal to or larger than the set accelerator operation amount and the slip ratio is equal to or smaller than the set slip ratio is the set time. If it continues for a long time, the upper control characteristic map with the increase rate of the throttle opening for the accelerator operation amount increased from the current control characteristic map is selected, and the higher control characteristic map is gradually selected. Map selecting means g for setting the set time short, target throttle opening value setting means h for obtaining a target throttle opening value based on the control characteristic map selected by the map selecting means g and the accelerator operation amount. And a control signal that causes the actual throttle opening value to match the target throttle opening value. A throttle valve opening control means j to be output to over data i, and a means, characterized in that it comprises a.

(Operation) When the vehicle travels such that a drive wheel slip occurs, if the slip ratio calculated by the map selecting means g exceeds the set slip ratio, the throttle opening degree with respect to the accelerator operation amount increases from the current control characteristic map. After the lower control characteristic map with the reduced ratio is selected and the lower control characteristic map is selected, the control characteristic map is held as it is until the slip ratio newly exceeds the set slip ratio.

Therefore, the control for holding the lower map does not immediately return to the previous drive force level at which the drive wheel slip occurred, even after the drive wheel slip has been avoided, and re-slip is prevented. Further, since the map is further dropped when the slip ratio newly exceeds the set slip ratio, the control is performed only in the decreasing direction of the driving force, so that hunting does not occur due to the increase or decrease of the driving force, and rattling vibration is prevented.

When the map selection means g is in a region where the accelerator operation amount is equal to or larger than the set accelerator operation amount and the slip ratio is equal to or smaller than the set slip ratio for a set time during traveling in which the occurrence of the drive wheel slip is suppressed. In addition, a higher control characteristic map in which the increase rate of the throttle opening with respect to the accelerator operation amount is increased from the current control characteristic map is selected. Here, the set time is set to a shorter time as the control characteristic map is gradually shifted to a higher level.

Therefore, when the lower map is selected and the map is initially raised, the map position shifts to the upper map after the condition that the accelerator operation amount condition and the slip ratio condition are satisfied continues for a long set time. Therefore, it is possible to have a time margin for making a decision as to whether or not it is optimal, and re-slip based on the engine response characteristic is prevented.

Also, as the set time becomes shorter as the selection and transition to the higher control characteristic map is performed step by step, when the road surface friction coefficient changes from the low friction coefficient road to the high friction coefficient road, The transition is accelerated faster, the throttle is returned in a short time, and the driver's expectation of acceleration can be satisfied.

In addition, ergonomically, the accelerator operation by the driver when entering from a low friction coefficient road to a high friction coefficient road shows an operation pattern of first stepping slowly from the caution of slip and then gradually increasing the stepping speed. Therefore, the acceleration state due to the control content that the set time becomes shorter as the selection and transition to the higher control characteristic map gradually becomes close to the acceleration state obtained by the actual accelerator operation, and the driver feels uncomfortable. Never give.

(Example) Hereinafter, an example 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 described as an example.

 First, the configuration of the embodiment will be described.

The power train P of the rear-wheel drive vehicle to which the driving force control device A of the embodiment is applied is, as shown in FIG.
0, transmission 11, propeller shaft 12, rear differential 13, rear drive shafts 14, 15,
It has rear wheels 16 and 17.

 The front wheels 18, 19 are non-drive wheels.

The driving force control apparatus A of the embodiment mechanically disconnects an accelerator pedal 20 which is an accelerator operator and a throttle valve 22 which is provided in a throttle chamber 21 which is an intake system of the engine 10 from an accelerator control wire or the like. A control device provided between the accelerator pedal 20 and the throttle valve 22 in place of the mechanical connecting means of the rear wheel rotation speed sensor 30, the right front wheel rotation speed sensor 31, and the left front wheel rotation speed sensor 32 as input sensors. , An accelerator potentiometer 33, a throttle valve control circuit 34 as arithmetic processing means, and a step motor as a throttle actuator.
Equipped with 35.

The rear wheel speed sensor 30 is a drive wheel speed detecting means,
Provided on the input shaft portion of the rear differential 13,
Outputting a wheel rotation signal after corresponding to the rear wheel rotation speed V _R (vr).

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), the throttle valve control circuit
In the input interface circuit 341 in 34, the F / V converter converts the voltage to a voltage corresponding to the frequency of the pulse signal, and the A / D converter converts the voltage value to a digital value.
Loaded to PU342 and memory 343.

The right front wheel speed sensor 31 and the left front wheel speed sensor 32
Is a detecting means of the vehicle speed, each provided in the axle portion, the front right wheel rotation signal corresponding to the right front wheel rotational speed V _FR and the left front wheel speed V _FL (vfr) and left wheel rotation of the front wheel 18, 19 Output signal (vfl).

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

The accelerator potentiometer 33 is a means for detecting the absolute accelerator operation amount 1 and is provided at the position of the accelerator pedal 20, and outputs an absolute accelerator operation amount signal (l) corresponding to the absolute accelerator operation amount l.

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 previously stored in the memory 343 in accordance with a predetermined arithmetic processing procedure,
An electronic circuit centered on a microcomputer that outputs a pulse control signal (c) to a step motor 35 serving as a throttle actuator. As an internal circuit, an input interface circuit 341 and a CPU (Central Processing
A unit) 342, a memory (RAM, ROM) 343, and an output interface circuit 344.

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

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

Further, in the memory 343 of the throttle valve control circuit 34, as shown in FIG. 4, the relational characteristic of the throttle opening change amount Δθ with respect to the relative accelerator operation amount Δl is set as a cubic curve characteristic.

The throttle valve control circuit 34 includes a slip ratio calculating means, a relative accelerator operation amount detecting means, an actual throttle opening detecting means, a map selecting means, a throttle opening change amount calculating means, and a target throttle opening means described in the claims. A degree detection means and a throttle valve opening / closing control means are included.

Note that the actual throttle opening detection means receives a STEP command signal from the CPU 342 of the throttle valve control circuit 34 to the output interface circuit 344 at the same time in the memory 343.
It is a means of an internal circuit configuration for writing and counting the number of STEPs in 43, and the actual throttle opening value θ ₀ is read out to the CPU 342 at any time according to a read command from the CPU 342.

The map selection means includes a map up selection means and a map down selection means.

The stepping motor 35 is an actuator that opens and closes the throttle valve 22.The stepping motor 35 includes a rotor and a plurality of stators having excitation windings. Rotate one step at a time.

 Next, the operation of the embodiment will be described.

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

The processing in the main routine of FIG. 5 is performed by a predetermined period (for example, an operating system (not shown)).
20msec) is a fixed-time interrupt process started at
The process in the subroutine shown in the figure is an oci (output compare interrupt) interrupt process appropriately started in the main routine in accordance with the signal output cycle to the step motor 35 determined by the fixed time interrupt.

(A) Initial setting The main routine shown in FIG. 5 is started from the point when the engine key is inserted into the key cylinder and the ignition switch is switched 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
In addition to setting G = 0, all other information such as FLG and reference values l ₀₀ and θ ₀₀ are cleared.

(B) Slip Ratio Calculation Processing The calculation processing of the slip ratio S between the tired road surfaces is performed in steps 102 to 107.

First, the rear wheel rotation speed V _R , the right front wheel rotation speed V _FR , and the left front wheel rotation speed V _FL are read based on the input signals from the rotation speed sensors 30, 31, 32 (step 102), and then the front wheel rotation is performed. speed
V _F is calculated (step 103).

The formula for calculating the front wheel rotation speed V _F is And it is determined by an average value.

Next, whether wheel rotation speed V _R after a driving wheel 40 km / h or more is determined (step 104), the process proceeds to step 105 in the case of _{V R ≧ 40 (km / h} ), in step 105 The slip ratio S is calculated.

The equation for calculating the slip ratio S is: Is.

When it is determined that _{V R <40 (km / h} ) in the step 104, the front and rear wheel rotational speed difference ΔV (= V _R -V _F) is calculated (step 106), obtained by the calculation The slip ratio S is set according to the front and rear wheel rotation speed difference ΔV (step 107).

Accordingly, the slip ratio S obtained in step 105 or step 107 is represented in a graph as shown in FIG. 7, and this slip ratio S is set to the set slip ratios S ₀ and S _{1 by the} following control operation. , the threshold when compared to S _2.

(C) Control Information Setting Process The control information setting process used in the map selecting process and the accelerator work determining process, which will be described later, is performed in steps 150 to 154.

First, 1 cycle is sampled in the processing two cycles before.
The accelerator pedal depression amount, which was treated as the absolute accelerator operation amount l ₁ in the previous cycle, is set as the absolute accelerator operation amount l _{2 two} times before (step 15
0).

Further, the amount of depression of the accelerator pedal, which was sampled in the processing one cycle before and treated as the absolute accelerator operation amount l ₀ this time, is set as the previous absolute accelerator operation amount l ₁ (step 151).

Next, the current accelerator pedal depression amount, as the current absolute amount of accelerator operation l _0, also the current throttle valve opening is read is sampled as an actual throttle opening value theta ₀ (step 152).

Next, by subtracting the previous absolute accelerator operation amount l ₁ from the set current absolute accelerator operation amount l ₀ ,
The current relative accelerator operation amount ΔL _0, which is the amount of change in the accelerator pedal depression amount from the processing one cycle before, is calculated (step 153), and the previous absolute accelerator operation amount l ₂ is calculated from the previous absolute accelerator operation amount l _1. 2 by being deducted
The previous relative accelerator operation amount ΔL ₁ that is the amount of change in the accelerator pedal depression amount that has changed from the processing time before the cycle to the processing time before the one cycle is calculated (step 154).

(D) Map upstream selection process This process is performed when the region control characteristic is in the region control characteristic map lower than the uppermost region control characteristic map by the map dropping selection means described later.

A map ascending selection process for selecting a higher region control characteristic map in which the increase rate of the throttle opening θ with respect to the absolute accelerator operation amount 1 is selected from the currently selected region control characteristic map is performed in steps 400 to 417.

First, it is determined whether or not the absolute accelerator operation amount l ₀ this time is greater than or equal to the high set accelerator operation amount l _H (step 40
0).

The high setting accelerator operation amount l _H in Example, when set to 1 maximum accelerator operation amount is set to l _H = 3/4 is a kick-down area boundaries.

Further, it is determined whether or not the absolute accelerator operation amount l ₀ this time is equal to or larger than the low set accelerator operation amount l _L (step 40
2). Note that the low accelerator operation amount l _L in the embodiment is set to l _L = 1/4 as a low accelerator operation region boundary.

Then, in step 400, l ₀ <l _H and in step 402, l ₀ >
(For i.e. _{l L ≦ l 0 ≦ l H} ) if it is determined that the l _L, if this relative accelerator operation amount [Delta] L ₀ Do [Delta] L _0> 0, ie, whether it is at depressed against the accelerator pedal 20 It is judged whether or not (step 403), and then the slip ratio S
Is S ≦ S ₀ (for example, S ₀ = 0.1), that is, it is determined whether or not the drive wheel slip has hardly occurred at the set slip ratio S ₀ or less (step 404), and then the actual throttle opening is performed. Whether the degree value θ ₀ is θ ₀ ≧ θ _MAX , that is, the actual throttle opening value θ ₀ is the throttle opening upper limit value θ _MAX according to the previously selected area control characteristic map.
Is determined (step 405), and then MAPFLG is MAP.
It is determined whether FLG = 0, that is, whether or not the maps are maps # 1 to # 7 capable of ascending the map (step 40).
6) Proceed to step 407 only when all of these map upstream conditions are satisfied, and the MAPFLG number (# 1 to # 7)
Is lowered first (step 407), and the area control characteristic map shifts to a map one step higher.

When any one of the map ascending conditions described in steps 403 to 406 is not satisfied, the area control characteristic map selected at that time is held until all of the map ascending conditions are newly satisfied.

If it is determined in step 400 that l ₀ ≧ l _H, it is determined whether the slip ratio S is S ≦ S ₀ (for example, S ₀ = 0.1) (step 408), and S ≦ S ₀ Time is step 4
The process proceeds to the timer process from 09 to step 416.

In step 409, it is determined whether or not the timer “TMR” has timed up for 0.6 sec, and if the timer is up, the timer value is continuously increased (step 414). Furthermore, in step 415, whether MAPFLG is MAPFLG = 0, That is, it is determined whether or not the maps are maps # 1 to # 7 capable of going up the map, and if the maps are maps # 1 to # 7, step 41
Proceeding to step 6, the number of MAPFLG (# 1 to # 7) is lowered by 1, and the map moves to the map one step higher as the area control characteristic map.

In steps 410 and 411, similarly to step 409, it is determined whether or not the timers of 1.0 sec and 1.2 sec have been timed up, and if the timers are up, the timer value is continuously increased and the control characteristic map is set in one step. Move to higher map.

In step 412, after 1.3 seconds, the control characteristic map is shifted to the upper map every control cycle until MAPFLG = 0.

The above steps 408 to 417 will be collectively described. When the accelerator operation amount is l _H (= 3/4) or more and the slip ratio S is S ₀ (= 0.1) or less, 0.6 sec after 1 sec. One more sheet after 1 second, one more sheet after 1.2 seconds,
One more sheet every 1.3 seconds, and every one cycle thereafter (20 mse
In c), the map moves to the upper level exponentially one by one.

(E) Map drop selection process The map drop selection process of selecting a lower region control characteristic map in which the increase ratio of the throttle opening θ with respect to the absolute accelerator operation amount 1 is reduced from the currently selected region control characteristic map is step 120. Step 131 is performed.

First, the slip ratio S and the first set value S ₁ (for example, S ₁ = 0.
1) is compared with, and the upper limit for dropping one map is S> S ₁
It is determined whether or not the drive wheel slip has occurred (step 120). If S> S ₁ , the process proceeds to the next step 121, and it is determined whether FLAG · A = 0 or not, and FLAG · A = If it is 0, FLAG · A = 1 is set (step 122), and in the next step 123, MAPFLG = 7.
It is judged whether or not, and when MAPFLG ≠ 7, the condition for dropping one map (S> S ₁ and MAPFLG ≠ 7) is satisfied.
The MAPFLG number (# 0 to # 6) is increased by 1 (step
124), and shifts to a map one step lower as the area control characteristic map.

Incidentally, after the map one drop is performed in step 124, it is determined that S ≦ S ₁ in step 120, is set to FLAG · A = 0 after the lapse of step 125, moreover, a new S>
Unless the S _1, selection processing of one drop map is not performed, area control characteristic map selected by the map one drop at step 124 is maintained.

However, when FLAG · A = 1, the process proceeds from step 121 to step 126, and it is not the case where the condition of S> S _{2 for} map dropping described later is satisfied.

When the process proceeds from the step 124 to the next step 126, the slip ratio S and the second set value S ₂ (for example, S ₂ = 0.3)
Bets are compared, if S> or S ₂ is one drop condition maps, namely excessive if the drive wheels slip has occurred is judged, S> The next step 127 in the case of S ₂
It is determined whether FLAG B = 0 or not, and FLAG B = 0
, FLAG · B = 1 is set (step 12).
8) In the next step 129, it is determined whether or not MAPFLG = 7. When MAPFLG ≠ 7, the condition of dropping one map (S> S ₂ and MAPFLG ≠ 7) is satisfied, and thus the number of MAPFLG ( #
0 to # 6) is incremented by 1 (step 130), and the area control characteristic map shifts to the map one step lower.

Incidentally, after the map one drop is performed in step 130, it is determined that S ≦ S ₂ in step 126, is set to FLAG · B = 0 after the lapse of step 131, moreover, a new S>
Unless the S _2, not performed the selection process of one drop map, map one area control characteristic map selected by drop in step 130 is maintained.

(F) Setting of the area control characteristic map In step 140, the MAPFLG selected based on the progress of the above-mentioned map ascending selection processing and map asking selection processing is performed.
The area control characteristic map having the same number as the number is set.

(G) When the map holding process l ₀ ≦ l _L , the steps 403 to 407 of the map ascending selection process are bypassed in the above-mentioned step 402.
This means that the currently selected area control characteristic map is kept as it is.

The absolute amount of accelerator operation l ₀ this step 164 it is determined whether it exceeds the low setting accelerator operation amount l _L, l _0> acceleration work determination process to be described later in step 155～ step 157 when the l _L is When l ₀ ≦ l _L, no matter what accelerator operation is performed, Steps 158 and 159
The throttle opening θ along the lower limit of the selected region control characteristic map to update the reference values l ₀₀ and θ _00.
Becomes

In addition, the low set accelerator operation amount l _L in the embodiment is set to 1 _L = 1/4 as a small accelerator operation region boundary.

Further, when l ₀ ≦ l _L , the above-mentioned step 402 bypasses steps 403 to 407 of the map ascending selection process, so that the selected area control characteristic map is held as it is.

(H) Accelerator work discrimination processing The accelerator work discrimination processing is based on the relative accelerator operation amount ΔL.
By determining that the constant speed traveling accelerator is operated as a reference for obtaining, in order to determine whether or not the constant speed traveling accelerator is operated, steps 155 to 155 are performed based on the information obtained in steps 150 to 154. This is the process performed in 159.

First, the accelerator work determination logic uses the previous relative accelerator operation amount ΔL ₁ and the current relative accelerator operation amount ΔL ₀ ,
When it is determined that the accelerator pedal 20 is being operated in the depressing direction continuously after the processing of the accelerator pedal 20 two cycles before (positive in step 155 and positive in step 156), or When it is determined that the deceleration accelerator operation is being performed during the return operation (negative in step 155 and negative in step 157), the next step 160
Proceed to.

When the accelerator pedal 20 is stopped and held at that position (negative in step 155, affirmative in step 157), when the operating direction of the accelerator pedal 20 is switched from the stepping direction to the returning direction (step 155). Positive in
When switching is made in step 156 (negative in step 156) or vice versa (negative in step 155, positive in step 157)
In step 158, it is determined that the change amount of the accelerator pedal depressing amount shifts from an increase including 0 to a decrease including 0, or from a decrease to an increase, at the time of a constant speed accelerator operation.
This time the absolute accelerator operation amount l ₀ is the accelerator operation amount reference value l ₀₀
As set, further the actual throttle opening value theta ₀ of this process proceeds to step 159 is set as a throttle opening reference value theta _00.

(I) Relative accelerator stroke calculation processing After the above-described accelerator work determination processing is performed, the routine proceeds to step 160, where the relative accelerator operation amount ΔL is calculated.

The equation for calculating the relative accelerator operation amount ΔL is ΔL = l ₀ −
Since it is l ₀₀ , at the time of acceleration accelerator operation or deceleration accelerator operation, it is calculated as the accelerator operation change amount from the time when the constant speed traveling accelerator operation is first performed to the absolute accelerator operation amount l ₀ this time. Further, at the time of the first constant speed traveling accelerator operation, ΔL = l ₀₀ −l ₀₀ , and the relative accelerator operation amount Δ
L becomes zero.

(V) Throttle opening change calculation In step 170, the throttle opening change Δθ is calculated based on the relative accelerator operation amount ΔL obtained in step 160 and the ΔL-Δθ characteristic diagram shown in FIG.

(L) Target throttle opening value setting process Temporary target throttle opening value θθ obtained by the throttle opening reference value θ ₀₀ and the throttle opening change amount Δθ calculated in step 170, and set in step 140 The target throttle value is compared by comparing the throttle control upper limit value θ _MAX and the throttle opening lower limit value θ _MIN obtained by the absolute control value l ₀ (or the accelerator operation amount reference value l ₀₀ ) of the current region control characteristic map. Opening value θ ^*
The process of setting is performed in steps 180 to 185.

First, the provisional target throttle opening value θθ is calculated in step 180.
And the throttle opening reference value θ ₀₀ and the throttle opening change amount Δ
is calculated by adding θ and θθ = θ ₀₀ + Δθ.

The process of comparing the provisional target throttle opening value θθ with the throttle opening upper limit value θ _MAX and the throttle opening lower limit value θ _MIN first determines whether the provisional target throttle opening value θ θ is greater than or equal to the throttle opening upper limit value θ _MAX. Is determined (step 181),
throttle opening upper limit theta _MAX is set as the target throttle opening value theta ^* in the case of θθ> θ _MAX (Step 18
2). Further, the provisional target throttle opening value Shitashita whether less throttle opening lower limit theta _MIN is determined in the case of θθ ≦ θ _MAX (step 183), θθ <throttle opening lower limit in the case of theta _MIN theta _MIN is set as the target throttle opening value θ ^* (step 184). Also, θ _MIN ≦ θθ ≦
In the case of θ _MAX , the provisional target throttle opening value θθ is set as it is as the target throttle opening value θ ^* (step 185).

That is, the target throttle opening degree value θ ^* is set as a value existing in the area of the selected area control characteristic map.

(Wo) When the target throttle opening value theta ^* is determined by the throttle valve opening control process target throttle opening value setting process described above, the throttle the actual throttle opening value theta ₀ in a direction to match the target throttle opening value theta ^* Processing for operating the valve 22 is performed in steps 200 to 202 in the main routine of FIG. 5 and steps 300 to 304 in the subroutine of FIG.

First, the deviation ε is calculated by subtracting the actual throttle opening value θ ₀ from the target throttle opening value θ ^* (step
200), calculation of the motor speed of the step motor 35, determination of forward rotation, reverse rotation, and holding, and a start cycle of the oci interrupt routine are obtained based on the deviation ε obtained by this calculation (step 201). The oci interrupt routine (FIG. 6) is started according to the operation control content of the step motor 35 set in 201 (step 202).

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

First, a determination is made as to whether or not a holding command to output the state of the step motor 35 is maintained (step 30).
0) When the holding command is output, step motor 3
Hold the stator side excitation state of 5 (step 301).

In addition, except when holding command is output, step motor
It is determined whether or not it is the time to output a reverse rotation command to reverse 35 (step 302).
TEP is set to STEP-1 (step 303), and the pulse signal for obtaining STEP-1 is output to the step motor 35 (step 301). Further, at the time of outputting a normal rotation command for rotating the step motor 35 in the normal direction, STEP is set to STEP + 1 (step 304), and a pulse signal for obtaining STEP + 1 is output to the step motor 35 (step 301).

Note that this oci interrupt routine is repeated within the activation cycle of the main routine according to the activation cycle set in step 201.

Next, the overall map ascending control will be described with reference to the throttle opening control operation diagram shown in FIG.

First, this control operation is an example of the case where the vehicle is driven from a snow road or the like where drive wheel slip is likely to occur to a dry road where drive wheel slip is not likely to occur and an acceleration operation is performed. Map # 6 is selected on the snow road. This is the case of acceleration from the start of the vehicle when the vehicle is in motion.

a) When l <1/4 When the absolute accelerator operation amount l is l <1/4, the process proceeds to step 158 and step 159 according to the determination in step 164 of the above-described flowchart, and the reference values l ₀₀ and θ _{00 are} always maintained. Therefore, the throttle valve 22 opens along the lower limit of the map # 6 no matter what accelerator operation is performed after the vehicle is stopped.

b) When 1/4 <l <3/4 When the absolute accelerator operation amount 1 is 1/4 <l <3/4, the judgment contents in steps 403 to 406 of the above-mentioned flowchart, that is, ΔL ₀ > 0, S ≦ S ₀ , θ ₀ ≧ θ _MAX , MAP
When all the conditions of FLG ≠ 0 are satisfied, the area control characteristic map goes up to the upper map.

Therefore, when the accelerator pedal 20 is being depressed and if the above-described map ascending condition is satisfied, the map is sequentially ascended in response to an increase in the absolute accelerator operation amount 1 as shown in the drawing. The throttle valve 22 opens while gradually increasing the opening gain of the throttle opening θ.

c) When l ≧ 3/4 When the absolute accelerator operation amount l is l ≧ 3/4, the determination contents in steps 409 to 412 of the above-described flowchart, that is, S ≦ S ₀ continues for four types of set times. , MAPFLG
When all the conditions of ≠ 0 are satisfied, the area control characteristic map goes up to the upper map.

Therefore, if the above-described map ascending condition is satisfied while the accelerator pedal 20 is being depressed or kept depressed, as shown in FIG.
Every time ec, 0.4 sec ... Elapses, one area control characteristic map goes up, and the throttle valve 22 opens as the map goes up.

Next, with reference to the time chart shown in FIG. 9, the map ascending operation when entering from the low friction coefficient road (ice burn) to the high friction coefficient road (dry road) will be described.

It is assumed that the absolute accelerator operation amount 1 is held in a region of 3/4 or more.

First, when entering the dry road from the iceburn, the drive wheel slip subsides and the map up condition by time management is satisfied.
Move to 6 and if map # 6 continues for 0.4 sec, map # 5
When map # 5 continues for 0.2 sec, it moves to map # 4, when map # 4 continues for 0.1 sec, it moves to map # 3, and when map # 3 continues for 20 msec, it moves to map # 2, map # 4 When 2 continues for 20 mssec, it moves to map # 1, and when map # 1 continues for 20 msec, it moves to map # 0.

That is, the maps are exponentially moved one by one to the upper position, so that the map goes up from the map # 7 to the map # 0 where the full throttle opening is obtained about 1.36 seconds after entering the dry road.

As described above, in the driving force control device of the embodiment, the effects listed below can be obtained.

The set l-θ control characteristic map is the area control characteristic map, and the opening / closing control of the throttle opening θ is based on the relative accelerator operation amount ΔL based on the absolute accelerator operation amount l during constant speed traveling operation. Since it is carried out, the opening / closing control gain of the throttle valve 22 is obtained in accordance with the accelerator work within the map area, and it is possible to ensure both good acceleration performance of the vehicle and prevention of large vehicle speed changes during constant-speed running operation. .

As shown in FIG. 4, the ΔL-Δθ characteristic is a cubic curve characteristic, so that a jerky feeling when the accelerator is depressed by a small amount is prevented, and high acceleration can be secured when the accelerator is depressed a little. Is done.

As shown in FIG. 7, when the vehicle speed is low, the slip ratio S is obtained from the front and rear wheel rotation speed difference ΔV.
High detection accuracy and high calculation accuracy are not required at low vehicle speeds where the slip ratio S changes due to, and map up control, map drop control, and throttle fully closed control are performed by the calculated value of the slip ratio S due to calculation error. Nor.

In the small accelerator operation amount region where the absolute accelerator operation amount l ₀ is l ₀ ≤l _L this time, the region control characteristic map selected at that time is held without going up the map. Correspondence with degree θ is stable,
The throttle valve 20 does not open too much when the accelerator pedal 20 is slightly depressed when climbing the map, preventing large torque fluctuations in the low accelerator operation amount range and enabling fine accelerator operation. It is.

When l ₀ ≤l _L when starting when the vehicle is stopped, if the lower limit of the region control characteristic map is followed, the control gain of the throttle opening θ with respect to the absolute accelerator operation amount l should be minimized. It becomes possible to perform a more delicate accelerator operation.

This time, when the absolute accelerator operation amount l ₀ is l _L <l ₀ <l _H , the map ascending control of the region control characteristic map in the intermediate accelerator operation amount region is such that the slip ratio S is S when the accelerator pedal 20 is depressed. Since it is performed on condition that ≦ S ₀ , how to open the throttle valve 22 corresponds to the accelerator operation, the driver does not feel uncomfortable, and a natural acceleration feeling can be obtained.

Further, since the condition that the actual throttle opening value θ ₀ is the throttle opening upper limit value θ _MAX is added to the condition, there is no sudden increase in the engine driving force.

At this time, when the absolute accelerator operation amount l ₀ is l ₀ ≧ l _H , the map of the region control characteristic map in the high accelerator operation amount region is initially set in the state where the slip ratio S is S ≦ S _{0 for} a long set time (0.6 s).
ec or 0.4 sec) is performed on condition that it is continued, so there is a time margin to judge whether the map position is optimal for the road surface friction coefficient, and the engine delay response Reslip due to properties is prevented.

In addition, the setting time becomes shorter as the selection and transition to the higher control characteristic map gradually (0.2se
c, 0.1sec, 20msec), when the road surface friction coefficient changes from a low friction coefficient road to a high friction coefficient road, the upper transition of the control characteristic map accelerates faster, throttle return is performed in a short time, and the driver It is possible to satisfy the expectation of acceleration.

That is, by shortening the duration included in the map rising condition as the shift to the upper map side is made, both re-slip prevention and a sense of acceleration are achieved.

It should be noted that the condition that l ₀ ≧ l _H, which indicates the driver's willingness to accelerate, is added, and that the setting time becomes shorter as the selection and transition to the higher control characteristic map gradually progresses. Is similar to the acceleration state obtained by the actual driver accelerator operation from an ergonomic point of view, so that the driver feels strange even if there is no direct correspondence between the absolute accelerator operation amount 1 and the throttle opening θ. Never.

Map drop control of the region control characteristic map, the slip ratio S is S> S _1, because it is to be performed on condition that a FLAG · A = 0, 1 sheet map satisfies the map drop condition After the fall, the slip rate is once S ≦
Also it becomes S _1, or satisfies the map up condition, until the slip ratio S exceeds newly set slip ratio S ₁ or S ₂ in order to lower the area control characteristic map is held as it is, the driving wheel slip Even after the avoidance, there is no immediate return to the previous drive force level at which the drive wheel slip occurred, and re-slip is prevented.

In addition, the drive wheel slip is controlled only in the direction of reducing the driving force by decreasing the throttle opening θ so that the map further drops when the set slip ratio S ₁ exceeds the newly set value. There is no occurrence of hunting due to the increase and decrease of the force, and the rattling vibration is prevented.

The embodiment of the present invention has been described in detail above with reference to the drawings.
The specific configuration is not limited to this embodiment, and even if there are design changes and the like within the scope of the present invention, they are included in the present invention.

For example, although the embodiment shows an example in which a plurality of area control characteristic maps having upper and lower limits are set, a linear control characteristic map such as a straight line, a polygonal line or a curved line may be used, or an area control characteristic map having only an upper limit may be used. Good.

Further, in the embodiment, as the map ascending control condition in the high accelerator operation amount region, with an absolute accelerator operation amount of 3/4 or more,
When the slip ratio is 0.1 or less, set time is 0.6sec, 0.4sec,
Although the example of 0.2 sec, 0.1 sec ... is shown, specific numerical values are not limited to the values in the embodiment.

In addition, in the map drop control, the number of maps to be dropped may be determined according to the degree of increase in the slip rate in consideration of the time change rate of the slip rate.

Further, although one characteristic is shown as the ΔL-Δθ characteristic in the embodiment, for example, when the map # 0 is selected, Δθ based on the characteristic of the solid line is added when the characteristic shown by the dotted line in FIG. 4 is added. May be set, and when maps # 1 to # 7 are selected, Δθ may be set based on the characteristic of the dotted line. In this case, the control gain of the throttle opening with respect to the absolute accelerator operation amount is traveled. It can be adapted to the road surface condition, and the drive wheel slip can be prevented in advance.

Further, when the slip ratio exceeds a new set value, the throttle valve may be fully closed unconditionally to avoid a drive wheel slip at an early stage.

(Effects of the Invention) As described above, according to the present invention, a plurality of relations between the throttle opening and the accelerator operation amount are set as control characteristic maps, and the map drop occurs while monitoring the drive wheel slip ratio and the like. In the vehicle driving force control device that suppresses the drive wheel slip without feeling discomfort in the accelerator operation by performing the map raising process and the map raising process, if the calculated slip ratio exceeds the set slip ratio, the accelerator operation amount is calculated from the current control characteristic map. After selecting the lower control characteristic map with a lower throttle opening increase ratio, the control characteristic map is retained until the slip ratio newly exceeds the set slip ratio. If the accelerator operation amount is in the region of the set accelerator operation amount or more and the slip ratio is less than or equal to the set slip ratio, If it continues for the set time, select a higher control characteristic map that has a higher increase rate of throttle opening to accelerator operation amount than the current control characteristic map, and gradually shift to the higher control characteristic map. Since the map selecting means for setting the set time to be shorter is provided as it goes, the map dropping process while holding the selected lower map prevents re-slip, hunting and rattling vibration, and shifts stepwise. The higher the map is, the shorter the map selection waiting time is. The map raising process has the effect that both the prevention of re-slip and the satisfaction of acceleration expectation can be achieved without making the driver feel uncomfortable. To be

[Brief description of drawings]

FIG. 1 is a claim correspondence diagram showing a vehicle driving force control device of the present invention, FIG. 2 is an overall view showing a driving force control device of 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 characteristic map of a set region control characteristic, FIG. 4 is a characteristic diagram showing a relation between a relative accelerator operation amount and a throttle opening change amount set in a throttle valve control circuit of the embodiment device, and FIG.
FIG. 6 is a flow chart showing a main routine of control operation in the throttle valve control circuit of the embodiment, FIG. 6 is a flow chart showing a subroutine of control operation in the throttle valve control circuit of the embodiment, and FIG. Fig. 8 is a slip ratio threshold characteristic diagram, Fig. 8 is an explanatory diagram showing changes in throttle opening in map up control, and Fig. 9 is a map up map when entering from a low friction coefficient road to a high friction coefficient road. It is a time chart figure. a: Drive wheel speed detecting means b: Vehicle speed detecting means c: Slip ratio calculating means d: Accelerator operation amount detecting means e: Actual throttle opening value detecting means f: Map setting means g: Map Selection means h ... Target throttle opening value setting means i ... Throttle actuator j ... Throttle valve opening / closing control means

 ─────────────────────────────────────────────────── ─── Continuation of front page (56) Reference JP-A-54-88527 (JP, A) JP-A-63-134828 (JP, A) JP-A-63-147939 (JP, A)

Claims (1)

(57) [Claims] 1. A slip ratio calculating means for calculating a slip ratio between a tire and a road surface based on a wheel speed obtained from a driving wheel speed detecting means and a vehicle body speed obtained from a vehicle body speed detecting means, and an accelerator operation amount for an accelerator operator. Map for setting a plurality of control characteristic maps that show the accelerator operation amount detection means, the actual throttle opening value detection means that detects the actual throttle opening value in the throttle valve, and the relationship between the throttle opening and the accelerator operation amount When the slip ratio calculated by the calculation exceeds the set slip ratio, a lower control characteristic map in which the increase rate of the throttle opening with respect to the accelerator operation amount is reduced from the current control characteristic map is selected to set the lower control. After the characteristic map is selected, the control characteristic map will be used until the slip ratio newly exceeds the set slip ratio. In the region where the accelerator operation amount is equal to or more than the set accelerator operation amount, and when the state in which the slip ratio is equal to or less than the set slip ratio continues for a set time, the accelerator operation amount is compared with the current control characteristic map with respect to the accelerator operation amount. Map selecting means for selecting a higher control characteristic map with an increased rate of increase in throttle opening, and for setting the set time shorter as the selection control shifts to the higher control characteristic map stepwise, and the map. Target throttle opening value setting means for obtaining a target throttle opening value based on the control characteristic map selected by the selecting means and the accelerator operation amount, and control for matching the actual throttle opening value with the target throttle opening value And a throttle valve opening / closing control means for outputting a signal to the throttle actuator. The vehicle driving force control apparatus according to symptoms.