JPH05231520A - Method for controlling speed change of vehicle automatic transmission - Google Patents

Abstract

PURPOSE:To make a vehicle easy to start by preventing flipping of the vehicle in running or starting the vehicle on a road with a low coefficient mu of frictional resistance, such as a snowy road. CONSTITUTION:A parameter regarding the frictional resistance of a road surface is detected, and when the frictional resistance of the road surface is recognized as being small according to the detected parameter regarding the frictional resistance, shifts by automatic transmissions 3, 4, 5, at least to the lowest gear, are inhibited.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift control method for an automatic transmission for a vehicle, and more particularly to a shift control method for a low μ road such as a snow road.

[0002]

2. Description of the Related Art In a conventional automatic transmission for a vehicle, a shift pattern is set in advance according to a throttle opening (engine load) and a vehicle speed, and this shift pattern is used for detection. The shift stage is set according to the throttle opening and the vehicle speed, and the shift shift is automatically executed. The conventional automatic gear shift control method has no particular problem in gear shift on a flat road such as city driving, and the gear shift is smooth and comfortable. However, when traveling in the mountains, there are straight uphills, frequent bends, downhills that require strong engine braking, and long downhills. Then, some drivers perform a sudden acceleration on a downhill and perform a strong braking operation immediately before entering a corner. When traveling in such a mountain, it is quite difficult to select the optimum shift speed for the vehicle driving condition, the driver's driving intention, the road condition, etc., and the driving operation is easy even in the mountain traveling, and the vehicle's kinetic performance is improved. It is often required to obtain a more favorable driving feeling.

In response to such a request, a so-called "fuzzy control" is performed to select the optimum shift speed according to the above-mentioned vehicle operating state, and a shift control method is disclosed in, for example, Japanese Patent Laid-Open No.
-246546 and Japanese Patent Laid-Open No. 02-3738. These conventional shift control methods try to determine the optimum shift stage by estimating all shift positions for city driving and mountain driving by fuzzy reasoning. Therefore, the conventional shift control method by "fuzzy control" has drawbacks such as a large number of rules and a complicated membership function shape, and requires a large-capacity computer for practical use. .. Further, since there are many rules and the shape of the membership function is complicated, there is a problem that tuning is difficult and therefore expansion to multiple models is also difficult.

Further, if the shift control method by the "fuzzy control" is newly adopted, the conventional automatic shift control method does not cause a conventional shift shift to a driver who is familiar with driving on a normal flat road such as city driving. Under such circumstances, there is a problem in that the shift shift is executed due to a small change in the driving state, such as overcoming a small protrusion or slightly stepping on the accelerator, which gives an uncomfortable feeling.

On the other hand, in Japanese Unexamined Patent Publication No. 2-212655, various parameters representing the running state of a vehicle are detected, and fuzzy inference is performed based on the detected signal and a preset membership function to determine the magnitude of running resistance. When the running resistance value is larger than a predetermined value, a high load running shift map is selected instead of the normal running shift map, and a shift stage is determined based on this high load running shift map. Control methods have been proposed. However, in the proposed shift control method, the same shift map is used for the straight uphill road and the frequently bent uphill road. There is a problem that the shift control cannot be performed sufficiently.

Further, on a snowy road or the like having a small frictional resistance coefficient μ, the behavior of the vehicle is apt to change due to a slight disturbance such as overrun of a small protrusion, a change in driving force, a brake operation, or the like. Therefore, on a low μ road such as a snowy road, it is required to select a shift stage in which the change in driving force is as small as possible to prevent slip and enable stable running. The present invention has been made in view of such a problem, and in a road having a low frictional resistance coefficient μ such as a snow road, the vehicle can be easily started and a slip of an automatic transmission for a vehicle can be prevented. It is to provide a control method.

[0007]

In order to achieve the above object, according to the present invention, in a shift control method for an automatic transmission for a vehicle having a plurality of shift speeds including a minimum speed, a road surface friction resistance is provided. When the road surface frictional resistance is determined to be small based on the detected parameter value related to the detected frictional resistance, at least the shift shift to the lowest speed is prohibited. A method for controlling a shift of an automatic transmission for a vehicle is provided.

The present invention can be suitably applied when the vehicle is started, and when it is determined that the detected frictional resistance is small, the vehicle is prohibited from starting at least at the lowest speed stage when the vehicle is started. Is good. For the determination of the frictional resistance of the road surface, for example, the frictional resistance value detected when the vehicle is running is stored, and the sum of the frequencies at which the frictional resistance value less than or equal to the first predetermined value is detected is greater than or equal to the second predetermined value. Or not.

Preferably, it is detected when the vehicle is running,
The parameter value related to the frictional resistance is stored, and when the sum of the frequencies of detection of the parameter values equal to or lower than the first predetermined value corresponding to the low μ road is equal to or higher than the second predetermined value, the frictional resistance of the road surface is reduced. It is better to determine that Further, when the sum of the frequencies is reduced to a value equal to or less than the second predetermined value, the road surface is maintained until the first predetermined time elapses from the time when the sum of the frequencies is reduced across the second predetermined value. It may be determined that the frictional resistance is small.

More preferably, when the time ratio in which the frictional resistance of the road surface is determined to be small during a predetermined period during running of the vehicle is equal to or more than a predetermined value, the vehicle is started at least at the lowest speed stage when restarting. It is good to ban. More preferably, a hydraulic pressure proportional to the steering wheel angle, the vehicle speed, and the cornering force acting on the vehicle when the steering wheel is operated is generated, and the hydraulic pressure of the steering device that assists the steering force is detected by the hydraulic pressure, and the road surface is detected from these detected values. The frictional resistance value may be detected.

[0011]

When the low gear having a large gear ratio is selected when the vehicle is running on a road surface where the frictional resistance of the road surface is judged to be small, or when the vehicle starts, the driving force changes greatly with a slight change in the accelerator opening. However, the tire easily slips.
Therefore, when it is determined that the frictional resistance of the road surface is small, at least the shift operation to the lowest speed stage is prohibited to avoid such an inconvenience.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Basic Concept of the Present Invention Prior to the description of the preferred embodiments, the basic concept of the present invention will be described with reference to FIG. Normal mode (MODE0) used for roads, uphill corner mode (MODE1) used on uphill slopes that frequently bend in the mountains, weak downhill engine brake used on running roads that require weak engine braking on loose downhill roads Mode (MODE2), strong downhill engine braking mode (MODE3) for use on a road that requires strong engine braking on a steep downhill or a downhill with a large degree of bending, a straight uphill road for a long straight uphill Each control mode of the mode (MODE4) is prepared.

In the normal mode 0, a shift pattern for traveling on a flat road such as an urban area is prepared in advance, and this shift pattern for traveling on a flat road is used to optimize the accelerator opening (engine load) and the vehicle speed. The method of setting various gears is no different from the conventional gear shift control method. When the mode 0 is selected, the shift stage is set by the shift control program prepared separately.

In the uphill corner mode 1, a shift pattern different from the flat road traveling shift pattern is prepared for traveling on an uphill curved road (details will be described later). The shift pattern is set so that the shift up shift is unlikely to occur, and shift hunting is prevented. In the downhill weak engine braking mode 2 and the downhill strong engine braking mode 3, the third speed and the second speed are forcibly set respectively, and the appropriate engine brake is automatically applied to prevent overrun at the corner of the downhill. Prevents speed entry and reduces brake operation.

In the straight uphill mode 4, the gear position is set one step lower than the current shift position, and the necessary driving force is secured. In this straight uphill mode 4, the downshift operation is automatically performed, so that the required driving force is secured and shift hunting is prevented. The shift control in the mode 4 is particularly effective for a vehicle having a small displacement. In the shift control method of the present invention, these control modes are fuzzy inference based on various fuzzy input variables representing a vehicle driving state, a driver's driving intention, and a road state, and a membership function (Klips set). Is selected by
The fuzzy shift position is set based on the selected control mode. Therefore, since all shift positions for city traveling and mountain traveling are not directly estimated by fuzzy inference to set the shift speed, the number of rules for selecting the control mode is small and the membership function is simple. .

The arrows between the control modes shown in FIG. 1, which will be described later in detail, indicate the direction of the control mode that can be switched from the current control mode. For example, the current mode is uphill corner mode (MODE1)
Then, it is possible to return from the mode 1 to the normal mode 0, and it is possible to directly switch to the downhill weak engine braking mode 2, but it is not possible to directly switch to the straight uphill road mode 4. It is not possible to directly switch from the normal mode 0 to the mode 3 strong downhill engine braking mode, and it must be switched via the mode 2 without fail.

Hardware Structure of Shift Control Device for Automatic Transmission FIG. 2 schematically shows a shift control device for an automatic transmission to which the method of the present invention is applied.
A gear transmission (T / M) 3 is connected to the output side of the / G) 1 via a torque converter 2. This transmission 3
Has, for example, four forward gears and one reverse gear, and a desired gear can be established by engaging or disengaging a brake or a clutch (not shown). The shift control device is provided with an operating hydraulic pressure control device 4 and controls the operating hydraulic pressure supplied to the above-mentioned brakes and clutches in response to a control signal from an electronic control unit (ECU) 5 described later. The transmission and the operating hydraulic pressure control device to which the method of the present invention is applied may have various types and hydraulic control for shift shift, and are not particularly limited.

The electronic control unit 5 sets an optimum shift speed for the vehicle operating condition and outputs a control signal corresponding to the shift speed set in the hydraulic pressure control unit 4 described above.
The hydraulic pressure control device 4 is connected to the output side of the electronic control device 5, and various sensors (not shown) are connected to the input side. These sensors supply the electronic control unit 5 with detection signals relating to the driver's driving intention, the operating state of the vehicle, including the engine 1, and the road state.

As these input signals (input variables),
The driver's accelerator pedal depression amount detected by the accelerator position sensor 10, that is, the accelerator position (opening) APS, the shift lever shift position SPOS detected by the shift position sensor 12, and the OD switch 14 for selecting the fourth speed ON / OFF signal OD, ON / OFF signal BRK of the brake switch 16 which is turned ON / OFF by the driver's depression of the brake petal, and the wheel speed sensor 1
8, the wheel speed signal for calculating the vehicle speed V0 and the longitudinal acceleration Gx acting on the vehicle, the engine speed signal Ne of the engine 1 detected by the engine speed sensor 20, and the intake air amount sensor 22 are detected. Intake air amount signal A / intake stroke of the engine 1 calculated from the air flow rate per unit time and the engine speed Ne
N, the turbine speed of the torque converter 2 detected by the turbine speed sensor 24 and the torque converter speed ratio (slip rate) e calculated from the engine speed Ne, and output from the electronic control unit 5 to the hydraulic pressure control unit 4. Commanded shift speed signal SHIF0, the calculated shift speed signal SHIF1 on the map determined from the shift pattern of mode 0, the steering wheel angle signal θw detected by the steering wheel angle sensor 28 and indicating the steering wheel operation amount of the driver, and the power steering. The power steering pressure signal PST and the like which are detected by the pressure sensor 28 and are obtained as the pressure difference between the left and right pressure chambers (not shown) of the front wheel steering actuator are included.

The information from the various sensors described above may be detected by a sensor specially provided for gear shift control, but even if this is not the case, most of that information is stored in the engine 1. Fuel supply control for injecting and supplying the required amount of fuel, antilock braking control during braking (AB
S control), traction control for controlling the output of the engine 1, and the like are also necessary, and thus necessary information may be obtained from these control devices.

The electronic control unit 5 includes input / output units 5A and 5A.
B, storage device 5C, central processing unit (CPU) 5D,
The input device 5A is composed of a counter device 5E and the like, and the input device 5A takes in the detection signals from the various sensors described above and performs filtering, amplification, A / D conversion, etc., while the output device 5B operates by the central processing unit 5D. Based on the result, the above-mentioned control signal is output to the hydraulic pressure control device 4.
The storage device 5C is constituted by a non-volatile RAM that is backed up by a battery and retains stored contents even when a key switch (not shown) is turned off, in addition to a normal RAM or ROM. The central processing unit 5D is the storage device 5
According to the shift control program stored in C, the control mode is determined by determining the vehicle operating state, the driver's driving intention, road conditions, etc., and the shift stage to be established is calculated based on the determined control mode. The details will be described later.

Shift Control Program Next, the procedure for calculating the fuzzy shift position in the shift control device described above and performing the fuzzy shift control based on the calculation result will be described with reference to the flowcharts shown in FIG. When the normal mode 0 is selected by the fuzzy shift control, the shift control in the normal mode 0 is executed by a separately prepared normal mode shift control program.

Main Routine First, the main routine (general flow) of the fuzzy shift control program shown in FIG. 3 will be described. This program is an initial processing routine in which control variable values and various stored values are set to initial values, a routine for inputting and calculating input variables from various sensors, etc., and fuzzy input variables are calculated from input or calculated input variables. routine,
Routine for setting the values of various fuzzy input switches from input variables, routine for determining whether a fuzzy rule is established, prepared according to the control mode currently being executed, and fuzzy shift position based on the established fuzzy rule And a routine for outputting the shift position based on the set fuzzy shift position and the like.

The initial processing routine is executed only once at the first time when the main program is executed, for example, only once immediately after the ignition key switch (not shown) is turned on. Then, when the execution of this initial processing routine is completed, each subsequent routine is repeatedly executed thereafter at a predetermined cycle (for example, 50 msec).

Input Variable Input / Calculation Routine This routine inputs input variables necessary for gear shift control from the various sensors described above, the fuel control device, or the like. Some input variables may be obtained by only filtering or A / D converting the detection signal directly input from the sensor, but there are also some input variables obtained by calculation from another input variable input.
Upper and lower limits are set for the input variable values as necessary, and those exceeding the upper and lower limits are limited to those upper and lower limits. The input variables required for gear shift control are shown in Table 1.

[0026]

[Table 1] A few of the input variables shown in Table 1 will be described below. The vehicle speed V0 is calculated from the wheel speed detected by the wheel speed sensor 18. In the case of gear change control, it is almost unnecessary to consider the slip amount of each wheel, so the vehicle speed V0 is
It may be calculated from the average value of the wheel speed of each wheel, or may be calculated from one of the wheel speeds of each wheel. Further, instead of obtaining from the wheel speed, the calculation may be performed from the rotation speed of the output shaft of the transmission. The longitudinal acceleration Gx is calculated from the time change of the vehicle speed V0. This longitudinal acceleration Gx
Since the detection accuracy of 1 has a great influence on the calculation accuracy of the weight / gradient resistance value described later, it is necessary to sufficiently filter to remove noise.

The steering wheel angle θw is set to an upper limit value when the absolute value thereof exceeds a predetermined upper limit value (for example, 360 °), and set to 0 ° when it is less than the lower limit value (for example, 10 °). To be done. The lateral acceleration Gy is regulated to a value of 0 when the vehicle speed V0 is a predetermined value (for example, 10 km / hr) or less, and to the upper limit value when the vehicle speed V0 exceeds a predetermined upper limit value. Lateral acceleration G
y is calculated based on the following expression (A1). Gy = (θw / ρ) / {Lw · (A + 1 / V0 ² )} × C1 (A1) where ρ is the steering wheel equivalent gear ratio, Lw is the wheel base (m), A is the stability factor, and C1 is It is a constant. In this embodiment, the lateral acceleration Gy is calculated on the basis of the vehicle speed V0 and the steering wheel angle θw by the above formula (A1), but an acceleration sensor may be attached to the vehicle body and directly detected by this sensor.

The engine torque ETRQ is read from a torque map preset according to the engine speed Ne and the intake air amount A / N, for example, using a known interpolation method. At this time, the maximum generated torque MXETRQ obtained by changing the intake air amount A / N for the same engine speed Ne from the torque map is also obtained and recorded at the same time.

Calculation of Fuzzy Input Variables Next, 11 fuzzy input variables FV (0) to FV (10) shown in Table 2 necessary for fuzzy inference are calculated. These fuzzy input variables FV (0) to FV (10) are
As shown in Table 2, it is classified into driver's driving intention information, vehicle operating state information, and road information. Although the steering wheel angle information of the road information is also the driver's intention information, the degree of bend of the road is determined from the steering wheel angle information and treated as road information. Further, the lateral acceleration information of the road information is also the vehicle operation information, but the bending degree of the road can be determined from this information as well, and is treated as the road information.

[0030]

[Table 2] Of the fuzzy input variables shown in Table 2, handle operation amount FV
(2) is the effective value of the product of the steering wheel angle and the lateral acceleration Gy, and the calculation of this effective value is performed every predetermined time (for example, every second).
Then, the average value of the effective values in the past predetermined period (for example, 20 seconds) is used as the parameter indicating the busyness of the steering wheel operation. The calculation procedure of the steering wheel operation amount will be described with reference to FIG.

First, the program control variable N1 is incremented by 1 (step S10). Then, it is determined whether or not the variable value N1 has reached a predetermined value (20) corresponding to a predetermined time (for example, 1 second) (step S1).
2) Then, step S10 and step S12 are repeatedly executed until the predetermined value is reached. When the variable value N1 reaches a predetermined value, the variable value N1 is returned to 0 (step S1).
4), step S16 is executed. That is, step S16 is executed every predetermined time (1 second).

In step S16, the steering wheel operation amount FV (2) is calculated by the following equations (A2) and (A3).

[0033]

[Equation 1] The calculation of the above formulas (A2) and (A3) is actually a predetermined time (1 second)
The product of each square value of the steering wheel angle θw and the lateral acceleration Gy detected for each is sequentially stored in a ring buffer containing 20 pieces of data, and sequentially erased to obtain the average value of the stored data. By calculating the square root, the effective value of the product of the steering wheel angle and the lateral acceleration Gy can be easily obtained.

Since both the steering wheel angle and the lateral acceleration factor are taken into consideration in this steering wheel operation amount FV (2),
When turning through the same corner, a higher vehicle speed has a larger value, and a smaller vehicle corner radius has a larger value at the same vehicle speed. Further, when the steering wheel angle is the same, the lateral acceleration is higher when the vehicle speed is higher, and the steering wheel operation amount FV (2)
Is a large value. In this way, the steering wheel operation amount FV
(2) can be regarded as an index including the frequency of steering wheel operations and the driver's tension.

For the steering wheel operation amount FV (2) obtained from 20 samples per second, comparing the values obtained during standard city driving, medium speed curved road driving, and zigzag bent road driving, The average value during driving is 3.0 (g ・ deg), and 10 to 30 (g
・ Deg), it is more than 40 (g ・ deg) when traveling on a zigzag curved road, and there is a significant difference in the steering wheel operation amount FV (2) when traveling on these roads, so traveling on these roads is determined. can do.

For example, in a city area, for example, even if a vehicle passes over a protrusion and a rule for discriminating an uphill road or a downhill road is established by another fuzzy input variable, this steering wheel operation amount FV (2) is equal to the above value. If it is 3.0 (g · deg) or less, it can be reliably determined that the vehicle is driving in the city.
The brake deceleration width FV (3), which is the fourth fuzzy input variable in Table 2, is the number of km / km at which the vehicle speed V0 is changed by one brake operation.
hr It indicates whether it has been dropped. Immediately after the brake switch is turned off, it may not be possible to accurately calculate the brake deceleration width FV (3) because it takes time to release the frictional engagement between the brake shoe of the brake device and the caliper. Therefore, immediately after the end of braking, the brake deceleration width FV
The calculation of (3) is prohibited for a predetermined time (for example, 0.3 seconds). The flowchart of FIG. 5 shows a procedure of calculating the brake deceleration width and prohibiting the calculation after the brake switch is turned off.

First, the electronic control unit 5 determines whether or not the brake switch BRK has a value of 1 (step S2).
0). The BRK value is 1 when the driver depresses the brake petal to perform a braking operation, and the BRK value is 0 when the driver releases his foot from the brake petal. If the driver does not perform any braking operation, the determination result of step S20 is negative (No), and in this case, step S2 described later.
After performing the determination of 2, the process proceeds to step S24, and the vehicle speed V0 detected this time is stored as the variable value VST. The variable value VST will be updated every time a braking operation is not performed, and the vehicle speed immediately before braking will be stored by this variable VST.

When the driver depresses the brake pedal, the determination result of step S20 becomes affirmative (Yes), and the process proceeds to step S26 to set the timer flag BFLG to the predetermined value XB.
(For example, a value corresponding to 0.3 seconds) is set, and the brake deceleration width FV (3) is calculated by the following expression (A4). The timer flag BFLG is a timer for measuring a predetermined time after the brake switch is turned off.

FV (3) = VST−FV (0) (A4) where VST is the vehicle speed stored immediately before the start of the braking operation, and FV (0) is the fuzzy input variable of the vehicle speed calculated this time. It is a value. Therefore, as long as the braking operation continues, step S26 is repeatedly executed, and the brake deceleration width FV (3) decelerated by the braking operation is updated. In the calculation in step S26, if VST <FV (0), the brake deceleration width FV (3) is set to the value 0.

When the driver releases his foot from the brake petal,
The determination result of step S20 is negative again, and it is determined in step S22 whether the timer flag BFLG is greater than zero. Immediately after the driver releases his / her foot from the brake petal, the BFLG value is set to the predetermined value XB, so the determination in step S22 is affirmative, and the process proceeds to step S28, in which the flag value BFLG is decremented by the value 1. At the same time, the brake deceleration width FV (3) is reset to the value 0. Then, until the flag value BFLG is subtracted to the value 1 and becomes the value 0, that is, the predetermined time (0.3 seconds)
Until step S28 is repeated,
During this period, the brake deceleration width FV (3) is prohibited from being calculated when the value 0 is set.

When the predetermined time (0.3 seconds) has elapsed, the determination result of step S22 becomes negative, and the above-mentioned step S2 is performed.
4 is executed and the updating of the variable value VST is repeated. The accelerator pedal depression speed FV (5) is the accelerator opening degree FV (4) detected at every predetermined time (for example, 0.25 seconds).
Is calculated by converting it into a difference for 1 second. In the embodiment, the accelerator depression speed FV (5) is obtained by multiplying the difference obtained every 0.25 seconds by four. The flowchart shown in FIG. 6 shows a procedure for obtaining the accelerator pedal depression speed FV (5), and the electronic control unit 5 first increments the program variable N2 by a value of 1 in step S30. This program variable N2 is used as an up-counter, and after incrementing, the variable value N2 is determined (step S32), and each time the variable value N2 reaches a predetermined value XN2 (value corresponding to 0.25 seconds), a step is performed. S34 and step S36 are executed.

In step S34, the program variable value N
2 is reset to the value 0, and in step S36, the accelerator depression speed FV (5) is calculated by the method described above. That is, first, the amount of change in the accelerator opening that has changed in 0.25 seconds is calculated by the following equation (A5). FV (5) = FV (4) −APSO (A5) where FV (4) is the accelerator opening A detected this time.
The value is set as it is using PS.
The variable APSO is the accelerator opening detected 0.25 seconds before, as described later. Next, as determined above, 0.
4 times the amount of change in accelerator opening that has changed in 25 seconds
Converted to the amount of change per second, this is the accelerator pedal speed FV
Reset as (5).

FV (5) = FV (5) × 4 (A6) Next, the accelerator opening degree FV (4), which is the fuzzy input variable set this time, is updated and stored as the variable value APSO. APSO = FV (4) (A7) This stored value APSO is used to calculate the amount of change in the accelerator opening after 0.25 seconds.

Next, a method of calculating the weight / gradient resistance FV (6) which is the fuzzy input variable shown in Table 2 will be described with reference to FIG. First, the electronic control unit 5 determines the vehicle speed FV (0).
Is below a predetermined value CFV0 (for example, 10 km / hr) or less (step S40). If the vehicle speed FV (0) is below a predetermined value CFV0, the weight / gradient resistance FV (6) is set to 0. In step S41, the current calculated value XR of the weight / gradient resistance is set to 0.0 (step S41), and the process proceeds to step S46 described later.

In step S40, the vehicle speed FV (0)
When it is determined that is greater than the predetermined value CFV0, the process proceeds to step S42, and it is determined whether or not a predetermined time (0.3 seconds) has elapsed during braking and from the end thereof. This determination is made based on whether the timer flag BFLG used in the above-described calculation routine for the brake deceleration width FV (3) is also used in this routine, and whether the timer flag BFLG is greater than 0. As described above, the timer flag BFLG is always reset to the initial value XB (the value corresponding to 0.3 seconds) during braking, and the value 1 from the end of braking to the value 0 (until the predetermined time elapses). The address is decremented. If the determination result of step S42 is affirmative, that is, if the predetermined time (0.3 seconds) has not yet elapsed during braking or when the braking ends, the weight / gradient resistance FV (6) cannot be calculated. Therefore, in this case, the previous value is held as it is as the current calculated value XR, and that value is used (step S
43). On the other hand, if braking is not being performed and a predetermined time has elapsed after braking, step S44
Then, the present calculated value XR of the weight / gradient resistance FV (6) is calculated as follows.

The weight / gradient resistance is obtained by subtracting the aerodynamic resistance, rolling resistance and acceleration resistance from the engine driving force, and is represented by the following expression (A8). XR = Engine driving force-Aerodynamic resistance-Rolling resistance-Acceleration resistance (A8) As mentioned above, weight / gradient resistance cannot be obtained during braking, but during vehicle turning, rolling resistance By including the resistance due to the cornering force, it is possible to calculate accurately. Above formula (A
The engine driving force in 8) is calculated by the following equation (A9). Engine driving force = T _E (η _E ) · t (e) · η · i _T · i _F / r (A9) where T _E (η _E ) is the engine torque after subtracting the exhaust loss ( kg · m), t (e) is the torque ratio of the torque converter 2, and is read out from a torque ratio table stored in advance as a function of the torque converter speed ratio e. η is the transmission efficiency of the transmission 3, i _F is the differential gear ratio, and these values are given as constants. i _T is the gear ratio of the transmission 3, and a predetermined gear ratio corresponding to the command variable SHIF0 that is an input variable is used. r is a dynamic radius (m) of the tire, and a predetermined value is used.

The aerodynamic resistance in the equation (A8) is calculated by the following equation (A10). The aerodynamic drag = ρa · S · Cd · V0 2/2 = C2 · V0 2 ... (A10) where, .rho.a is air density, the outside air temperature is given by a constant when constant. S is a vehicle front projection area, Cd is a drag coefficient, and these values are also constants. Therefore, the aerodynamic resistance can be calculated as a function of only the vehicle speed V0 when C2 is a constant, as in the equation (A10).

The rolling resistance in the equation (A8) is calculated by the following equation (A11). Rolling resistance ^{= R0 + (CF 2 / CP} ) ... (A11) here, R0 is the rolling resistance at the time of free-rolling, CF is cornering force, CP is a cornering power. The second term on the right side of the above equation is a contribution term due to the cornering resistance when the sideslip angle is small. The rolling resistance R0 during free rolling is calculated by the following equation (A12).

R0 = μr · W (A12) where μr is the rolling resistance coefficient and W is the vehicle weight. The load sharing ratio of the front and rear wheels is constant (for example, the front and rear ratio is 0.
6: 0.4), assuming that the cornering powers of the front and rear wheels are CPf and CPr (constant values), and considering the two-wheel model, the cornering resistance of equation (A11) should be calculated by the following equation (A13). You can

[0050]

[Equation 2] Here, C3 is a constant. Since the rolling resistance is made to include the cornering resistance in this way, the weight / gradient resistance when the steering wheel is greatly turned can be accurately calculated. That is, when the cornering resistance is not included, the gradient during cornering is calculated to be smaller than the actual value on the down bend road, and it may be presumed to be uphill when turning even on a flat road.By including the cornering resistance, These are eliminated.

The acceleration resistance in the equation (A8) is calculated by the following equation (A14). Acceleration resistance = (W + ΔW) · Gx (A14) Here, W is the vehicle weight described above, and ΔW is the rotating portion equivalent weight. The rotating portion equivalent weight ΔW is calculated by the following equation (A15). ΔW = W0 × {Ec + Fc (i T · i F) 2} ... (A15) here, W0 is unladen weight, Ec tire rotational portions corresponding weight percentage, Fc is the engine rotational portion corresponding weight ratio,
i _T and i _F are the gear ratio of the transmission 3 and the differential gear ratio described above.

When the calculation of the calculated value XR this time is completed as described above, the calculated calculated value XR is digitally filtered to remove noise (step S46), which is used as the fuzzy input variable FV (6). It is stored (step S48). The engine torque margin FV (7), which is a fuzzy input variable shown in Table 2, is calculated based on the following equation (A16).

FV (7) = MXETRQ-ETRQ (A16) where MXETRQ and ETRQ are the engine torque and the maximum engine torque read from the torque map in the input variable input / arithmetic routine.
Next, a method of calculating the 2-second difference FV (8) of vehicle speed, which is a fuzzy input variable shown in Table 2, will be described with reference to FIG.
It is preferable that the detected vehicle speed data be stored in the ring buffer every time the vehicle speed is detected in the control cycle (50 msec), and the 2-second difference FV (8) of the vehicle speed is calculated every time the vehicle speed is detected. If the capacity of the
For example, the difference may be obtained every 0.25 seconds, and the flowchart shown in FIG. 8 is such that the 2-second difference FV (8) of the vehicle speed is obtained every 0.25 seconds.

The electronic control unit 5 firstly executes step S50.
In step 1, the program control variable K1 is incremented by 1 and the variable value K1 is changed to a predetermined value XK1 (for example, 0.25
It is determined whether or not a value corresponding to seconds has been reached (step S52). The program control variable K1 is an up-counter for measuring a predetermined time (a period of 0.25 seconds in this embodiment), and steps S50 and S52 are repeatedly executed until the predetermined value XK1 is reached, and the predetermined time (0.25 seconds). ).

When the variable value K1 reaches the predetermined value XK1, step S54 is executed to reset the variable value K1 to 0. Then, after the vehicle speed V0 detected this time is stored in the ring buffer (not shown) in step S56, the latest vehicle speed data and the vehicle speed data two seconds before are taken out from the ring buffer and the two-second difference FV (8) between the vehicle speeds is obtained. Is calculated (step S58).

FV (8) = V0 _n −V0 _n−7 (A17) where V0 _n and V0 _n−7 are present and 2 respectively.
This is the vehicle speed detected two seconds ago. Therefore, the two-second difference FV (8) in vehicle speed is held at the same value for a predetermined time (0.25 seconds). The operation of the fuzzy input switch The fuzzy input switches SW (0) to SW (10) are used to calculate the goodness of fit in the same way as the membership function of the fuzzy input variable when the fuzzy rule is judged.
Since it is represented by a digital value, it is separated from the fuzzy input variable as a switch input. Table 3 shows these fuzzy input switches.

[0057]

[Table 3] The fuzzy input switch SW (0) represents the selected control mode, and its value is set in each mode processing described later.

The fuzzy input switch SW (1) is in the second state where the weight / gradient resistance is the predetermined value CFV61 or more in the first predetermined period (an appropriate value between 4 seconds and 10 seconds, for example, 5 seconds). If the vehicle continues for a predetermined time (an appropriate value between 2 and 5 seconds, for example, 2.5 seconds), it is determined that the vehicle is climbing an uphill slope, and the value 1 is set to the switch SW (1). Then, the large gradient resistance state is stored.
The above-mentioned first and second predetermined periods are experimentally set to appropriate values for each vehicle.

Next, this fuzzy input switch value SW
The setting procedure of (1) will be described with reference to FIG. First, in step S60, the electronic control unit 5 determines whether or not the weight / gradient resistance value FV (6) is smaller than a predetermined value CFV61 corresponding to a predetermined gradient degree of the road. If the determination result of step S60 is affirmative, that is, if the road gradient is small, the 2.5 second counter CNTSW1 is set to 0.
(Step S61), and the process proceeds to step S64. If the vehicle is continuously traveling on a road with a small slope, in this step S64, a 5-second counter CN described later will be used.
After confirming that T5S is 0 or less, step S
Proceeding to 65, the value 0 is set in the fuzzy input switch SW (1), and the routine ends.

The weight / gradient resistance value FV (6) is a predetermined value CF.
If it is determined that the vehicle is traveling on an uphill road having a large gradient with V61 or more, the 2.5 second counter C is determined in step S62.
After incrementing NTSW1 by the value 1, it is determined whether or not this counter value CNTSW1 has reached a predetermined value XCN1 (value corresponding to 2.5 seconds) or more (step S6).
3). If the counter value CNTSW1 is smaller than the predetermined value XCN1, that is, if the predetermined time (2.5 seconds) has not elapsed,
In step S64, it is determined whether or not the 5-second counter CNT5S is greater than 0. This 5 second counter CNT
5S is a down counter that measures the elapse of a predetermined period (for example, 5 seconds). If the determination in step S64 is affirmative, that is, if the predetermined period (5 seconds) has not elapsed, the 5 second counter CNT5S is obtained in step S66. Is decremented by 1 and the routine ends. If the weight / gradient resistance value FV (6) continuously exceeds the predetermined value CFV61 within the predetermined period (5 seconds), the 2.5-second counter CNTS
W1 will be incremented sequentially, but will
If the weight / gradient resistance value FV (6) does not continuously exceed the predetermined value CFV61 for less than a second) and becomes smaller than the predetermined value CFV61 midway, the 2.5 second counter CNTSW1 is reset (step S61), 5 Second counter CNT5S
Is continuously decremented (step S66).

Weight / gradient resistance value F within a predetermined period (5 seconds)
If the state in which V (6) is continuously the predetermined value CFV61 or more continues for the predetermined time (2.5 seconds), step S63.
The result of the determination in step 5 is affirmative, and step S67 is executed. In this step, 2.5 seconds counter CNTSW
1 is initial value 0, 5 second counter CNT5S is initial value XC
N2 (the value corresponding to 5 seconds) is reset, and the fuzzy input switch SW (1) is set to the value 1 to end the routine. Fuzzy input switch S
By setting the value 1 to W (1), the state in which the vehicle is climbing the uphill road with large gradient resistance is stored. In this way, by determining that the large gradient resistance state continues for the second predetermined period (2.5 seconds) during the first predetermined period (5 seconds), the vehicle is simply traveling on the uphill slope. Not only that, but also when, for example, turning a hairpin curve from a flat road and climbing a steep slope immediately after that, the vehicle climbing state can be accurately determined.

The fuzzy input switch SW (2) indicates that the vehicle is going downhill when the weight / gradient resistance is continuously greater than a predetermined negative value (-CFV62) for a predetermined time (for example, 2.5 seconds). It is determined that the vehicle has returned from the running state of
The value 1 is set in the switch SW (2) to store the non-negative state of the gradient resistance. This fuzzy input switch value S
The procedure for setting W (2) will be described with reference to FIG.

The electronic control unit 5 firstly executes step S70.
At, it is determined whether or not the weight / gradient resistance value FV (6) is smaller than a negative predetermined value (-CFV62) corresponding to a predetermined gradient degree of the road. If the determination result of step S70 is affirmative, that is, if the slope of the road is still negative, the process proceeds to step S72, the 2.5-second counter CNTSW2 is reset to the value 0, and the fuzzy input switch SW is set.
The value 0 is set in (2) and the routine ends.

On the other hand, if the weight / gradient resistance value FV (6) is equal to or greater than the negative predetermined value (-CFV62) and the gradient is not negative (non-negative), the 2.5 second counter CNTSW2 is incremented by 1 in step S74. After doing
It is determined whether or not this counter value CNTSW2 has reached a predetermined value XCN3 (value corresponding to 2.5 seconds) or more (step S76). The counter value CNTSW2 is the predetermined value XCN3
If it is smaller, that is, if the predetermined time (2.5 seconds) has not elapsed, the routine is ended without doing anything. In step S70, the weight / gradient resistance value FV (6) is greater than or equal to the negative predetermined value (-CFV62), it is determined that the gradient is in the non-negative state, and the counter value C is determined in step S76.
When it is determined that NTSW2 has reached the predetermined value XCN3, step S78 is executed and the 2.5 second counter CNT
The SW2 is reset to the initial value 0 and the fuzzy input switch SW (2) is set to the value 1 to end the routine. By setting the value 1 to the fuzzy input switch SW (2), it is remembered that the vehicle has returned to the road on which the gradient resistance is not negative.

The fuzzy input switch SW (3) is used to remove the vehicle from an uphill running state when the weight / gradient resistance is continuously below a predetermined value (CFV63) for a predetermined time (for example, 5 seconds). Switch SW
The value 1 is set in (3) to store the gradient resistance non-large state. Below, this fuzzy input switch value SW
The setting procedure of (3) will be described with reference to FIG.

The electronic control unit 5 firstly performs step S80.
At, it is determined whether or not the weight / gradient resistance value FV (6) is larger than a predetermined value (CFV63) corresponding to a predetermined road grade. When the determination result of step S80 is affirmative, that is, when the road gradient is still large, the process proceeds to step S82 and the 5-second counter CNTSW3 is set to 0.
Fuzzy input switch SW
The value 0 is set in (3) and the routine ends.

On the other hand, if it is determined that the weight / gradient resistance value FV (6) is less than or equal to the predetermined value (CFV63) and the condition in which the gradient is large is exited, that is, if it is determined that the condition is not large, then 5 is determined in step S84. Set the value 1 to the second counter CNTSW3
After incrementing only this counter value CNTSW
It is determined whether 3 has reached the predetermined value XCN4 (value corresponding to 5 seconds) or more (step S86). Counter value C
If NTSW3 is smaller than the predetermined value XCN4, that is, if the predetermined time (5 seconds) has not elapsed, the routine is ended without doing anything.

In step S80, it is determined that the weight / gradient resistance value FV (6) is less than or equal to the predetermined value (CFV63), and the gradient is in a non-large state, and the counter value CNTSW.
When it is determined that 3 has reached the predetermined value XCN4, step S88 is executed, the 5-second counter CNTSW3 is reset to the initial value 0, and the fuzzy input switch SW (3) is set to the value 1 to execute the routine. To finish. By setting the value 1 in the fuzzy input switch SW (3), it is stored that the vehicle has returned to the traveling road in which the gradient resistance is not large (end of climbing gradient).

The fuzzy input switch SW (4) is operated when the steering wheel operation amount FV (2) is continuously a predetermined value (CFV21) or more for a predetermined time (for example, 5 seconds).
It is determined that the vehicle is traveling on a winding road, the switch SW (4) is set to the value 1, and this state is stored. When it is determined that the vehicle has exited from the winding road, a steering wheel operation amount FV is determined using a predetermined value (CFV22) smaller than the above-described predetermined value (CFV21).
It is determined that (2) has become small. That is, a hysteresis characteristic is provided to determine whether the road is a meandering road. The procedure for setting the fuzzy input switch value SW (4) will be described below with reference to FIGS. 12 and 13.

The electronic control unit 5 firstly performs step S90.
At, it is determined whether or not the fuzzy input switch SW (4) has the value 0. This fuzzy input switch SW
If the value 0 is set in (4), step S91
If the value 1 is set, the step S in FIG.
Proceed to 96. The fuzzy input switch value SW (4) is 0
Then, if the determination result of step S90 is affirmative, the electronic control unit 5 executes step S91, and the steering wheel operation amount FV (2) is a predetermined value (CFV21) indicating that the steering wheel operation amount is large. It is determined whether or not it is smaller.
If the determination result of step S91 is affirmative, that is, if the steering wheel operation amount is not large, the process proceeds to step S92.
The 5-second counter CNTSW4 is reset to the value 0 and the routine ends.

On the other hand, when it is determined that the steering wheel operation amount FV (2) is equal to or larger than the predetermined value (CFV21) and the steering wheel operation amount is large, the 5-second counter CNT is determined in step S93.
After incrementing SW4 by the value 1, this counter value CNTSW4 is the predetermined value XCN5 (value corresponding to 5 seconds).
It is determined whether or not has reached (step S94). If the counter value CNTSW4 is smaller than the predetermined value XCN5, that is, if the predetermined time (5 seconds) has not elapsed, the routine is ended without doing anything.

In step S91, it is determined that the steering wheel operation amount FV (2) is equal to or larger than the predetermined value (CFV21), and the steering wheel operation amount is large, and the counter value CNTS.
When it is determined that W4 has reached the predetermined value XCN5, step S95 is executed, the 5-second counter CNTSW4 is reset to the initial value 0, and the fuzzy input switch SW (4) is set to the value 1 to perform the routine. To finish. By setting the value 1 to the fuzzy input switch SW (4), it is stored that the vehicle is running on a winding road.

When the fuzzy input switch SW (4) is set to the value 1, the determination result of step S90 becomes negative, and in this case, the electronic control unit 5 executes step S96 of FIG. In step S96, it is determined whether or not the steering wheel operation amount FV (2) is larger than a predetermined value (CFV22) set to a value smaller than the above-mentioned predetermined value (CFV21). If the determination result of step S96 is affirmative, that is, it is determined that the vehicle is still traveling on the winding road, the process proceeds to step S97, the above-mentioned 5 second counter CNTSW4 is reset to the value 0, and the routine ends.

On the other hand, when it is determined that the steering wheel operation amount FV (2) is smaller than the predetermined value (CFV22) and the steering wheel operation amount is small, after incrementing the 5-second counter CNTSW4 by the value 1 in step S98, It is determined whether or not this counter value CNTSW4 has reached a predetermined value XCN5 (value corresponding to 5 seconds) (step S9).
9). If the counter value CNTSW4 is smaller than the predetermined value XCN5, that is, if the predetermined time (5 seconds) has not elapsed,
The routine is ended without doing anything.

In step S96, the steering wheel operation amount FV (2) is smaller than the predetermined value (CFV21), and it is determined that the steering wheel operation amount is small, and the counter value CNTSW4 reaches the predetermined value XCN5 in step S99. If it is determined that step S100 is executed,
The 5-second counter CNTSW4 is reset to the initial value 0, and the fuzzy input switch SW (4) is set to the value 0 to end the routine. By setting the value 0 to the fuzzy input switch SW (4), it is memorized that the vehicle has made a staggered road.

In the fuzzy input switch SW (5), the accelerator opening FV (4) has a predetermined value CFV41 (for example, 25
%) Continues for a predetermined time (eg, 0.6 seconds), it is determined that the accelerator opening is large and the switch SW (5) is set to value 1 to set the accelerator opening large state. Is to remember. The setting procedure of the fuzzy input switch value SW (5) will be described below with reference to FIG.

The electronic control unit 5 firstly executes step S10.
1, the accelerator opening degree FV (4) is a predetermined value (CFV4
1) It is determined whether it is smaller than. Step S101
Is positive, that is, when the accelerator opening degree is smaller than the predetermined value (CFV41), step S10.
In step 2, the counter CNTSW5 is reset to the value 0, the fuzzy input switch SW (5) and the fuzzy input switch SW (7) are set to the value 0, and the routine ends. Fuzzy input switch SW
(7) is an accelerator strength flag at the time of engine braking of the third speed, and as will be described later in detail, the fuzzy input switch S
Immediately after W (5) is set to the value 1 in this routine,
When the accelerator opening FV (4) is equal to or larger than a predetermined opening CFV43 (for example, 40%), the value is set to 1 (routine in FIG. 26), and the driver has the intention of strong acceleration on a downhill. Memorize

On the other hand, when it is determined in step S101 that the accelerator opening degree FV (4) is equal to or greater than the predetermined value (CFV41), the counter CNT is determined in step S104.
After incrementing SW5 by the value 1, this counter value CNTSW5 is a predetermined value XCN6 (value corresponding to 0.6 seconds)
It is determined whether or not has reached (step S106). If the counter value CNTSW5 is smaller than the predetermined value XCN6, that is, if the predetermined time (0.6 seconds) has not elapsed, the routine is ended without doing anything.

If it is determined in step S101 that the accelerator opening FV (4) is equal to or greater than the predetermined value (CFV41) and the counter value CNTSW5 has reached the predetermined value XCN6, step S108 is executed and the counter C
The NTSW 5 is reset to the initial value 0, and the fuzzy input switch SW (5) is set to the value 1 to end the routine. By setting the value 1 to the fuzzy input switch SW (5), the large accelerator opening state is stored.

In the fuzzy input switch SW (6), the accelerator opening FV (4) has the above-mentioned predetermined value CFV41 (2).
The predetermined value CFV42 set to a value smaller than 5%)
(For example, 15%) is greater than a predetermined time (for example,
When it continues for 0.6 seconds, the accelerator opening degree is determined to be in the middle state, the switch SW (6) is set to the value 1, and the accelerator opening state is stored. The setting procedure of the fuzzy input switch value SW (6) will be described below with reference to FIG.

The electronic control unit 5 firstly executes step S11.
At 0, the accelerator opening degree FV (4) is a predetermined value (CFV4
2) Determine whether it is smaller than. Step S110
Is positive, that is, when the accelerator opening is smaller than the predetermined value (CFV42), step S11.
In step 2, the counter CNTSW6 is reset to the value 0, the fuzzy input switch SW (6) and the fuzzy input switch SW (8) are set to the value 0, and the routine ends. Fuzzy input switch SW
(8) is an accelerator strong flag at the time of the second speed engine braking, and as will be described later in detail, the fuzzy input switch S
Immediately after W (6) is set to the value 1 in this routine,
The accelerator opening degree FV (4) is equal to the above-mentioned predetermined opening degree CFV43.
It is set to a value of 1 when (for example, 40%) or more (see FIG. 3).
3 routine), memorize that the driver has the intention of strong acceleration on a downhill.

On the other hand, if it is determined in step S110 that the accelerator opening FV (4) is equal to or greater than the predetermined value (CFV42), the counter CNT is determined in step S114.
After incrementing SW6 by the value 1, this counter value CNTSW6 is the predetermined value XCN7 (value corresponding to 0.6 seconds).
It is determined whether or not has reached (step S116). If the counter value CNTSW6 is smaller than the predetermined value XCN7, that is, if the predetermined time (0.6 seconds) has not elapsed, the routine is ended without doing anything.

If it is determined in step S110 that the accelerator opening FV (4) is equal to or greater than the predetermined value (CFV42) and the counter value CNTSW6 has reached the predetermined value XCN7 in step S116, step S11
8 is executed, the counter CNTSW6 is reset to the initial value 0, the value 1 is set in the fuzzy input switch SW (6), and the routine is finished. By setting the value 1 to the fuzzy input switch SW (6),
The state during accelerator opening is stored.

Fuzzy input switches SW (9) and S
W (10) is set to the value 1 when it is determined that the friction coefficient μ of the road surface is low, and the switch S
W (9) indicates the short-term prediction result of the road condition by the switch S.
W (10) stores each long-term prediction result. Below, this fuzzy input switch value SW (9)
The setting procedure of SW and SW (10) will be described with reference to the flowcharts of FIGS.

The electronic control unit 5 firstly executes step S25.
At 0, the road surface μ value is calculated. Various methods have been proposed as a method for calculating the road surface μ. For example, Japanese Patent Laid-Open No. 60-148769 (corresponding U.S. Pat. The road surface μ is predicted from the actually detected steering angle and lateral acceleration.

Another method for obtaining the road surface μ has also been proposed. This alternative method is the power steering pressure signal P
The road surface μ is calculated based on ST, the vehicle speed V0, and the steering wheel angle θw, and the principle of calculating the road surface μ will be described below with reference to FIGS. 18 and 19. When the front wheels FW are steered, the right front wheels FW illustrated in FIG.
_If the inclination angle of the right front wheel FW _R with respect to the traveling direction of _R , that is, the sideslip angle is β _f , the cornering force C _F of the right front wheel FW _R can be expressed by the following equation.

C _F ∝ β f · μ Here, as is clear from the above equation, since the cornering force C _F is proportional to the product of the sideslip angle β _f and the road surface μ, when the road surface μ is different, that is, the road surface μ Under different conditions, even if the sideslip angle βf is the same, the cornering forces C _{F of the} wheels are significantly different. Specifically, FIG.
As is clear from the above, in a region where the sideslip angle βf is large,
The higher the road surface μ, the greater the cornering force C _{F of the} wheel. Incidentally, reference numeral 30 in FIG.
Is a front steering actuator, and 3 is a tie rod. Further, the reference symbol L indicates a line along the axial direction of the vehicle body, and the reference symbol δf is the right front wheel FW _R , that is,
The steering angle of the front wheels FW is shown.

As is clear from FIG. 18, it is understood that the cornering force C _F and the power steering pressure PST have a substantially proportional relationship in consideration of the dynamic equilibrium condition. Therefore, if the power steering pressure PST is used instead of the cornering force C _F and the above equation is rewritten, the following equation is obtained. PST = C ₁ · β f · μ (M1) where C ₁ is a constant.

On the other hand, the sideslip angle βf can be expressed by the following equation using the vehicle speed V0, the steering wheel angle θw and the road surface μ. βf = C ₃ · V 0 ² · θ w / (μ + C ₂ · V 0 ² ) (M2) where C ₂ and C ₃ are constants, respectively. Formula (M1) and (M2)
From the formula, the power steering pressure PST and the steering wheel angle θw
The ratio of, and PST / θw can be expressed by the following equation.

PST / θw = μ · C ₁ · C ₃ · V 0 ² / (μ + C ₂ · V 0 ² ) (M3) Therefore, the electronic control unit 5 controls the supplied power steering pressure signal value PST and the steering wheel angle signal. By substituting the value θw and the vehicle speed signal value V0 into the above equation (M3), the road surface μ
Can be calculated. Next, step S2 in FIG.
52, the control cycle (5
A histogram as shown in FIG. 20 is created from, for example, 100 pieces of data of road surface μ values detected every 0 msec), and a sum PBM of detection frequencies of road surface μ values smaller than a predetermined value XML (for example, 0.3) is obtained. Calculate Then, it is determined whether or not the sum PBM of the detection frequencies is equal to or more than a predetermined value XMU (for example, 50%) (step S254). If this determination result is affirmative, it is considered that the friction coefficient μ of the road surface is low, and the fuzzy input switch SW (9) is set to the value 1, and the value of the short-term counter CNTMUS is reset to 0 ( Step S256). Short-term counter CNT
In MUS, even if the sum PBM of detection frequencies becomes smaller than the predetermined value XMU and the determination condition of step S254 is not satisfied, the fuzzy input switch SW (9) is set to the value 1 for a while (for example, 20 seconds). It is for holding.

Therefore, the sum PBM of the detection frequencies is the predetermined value XM.
If it is smaller than U and the determination result of step S254 is negative, first, in step S258, it is determined whether or not the short-term counter value CNTMUS is greater than or equal to a predetermined value XCMS (a value corresponding to 20 seconds), While the predetermined time has not passed, step S260 is skipped and the fuzzy input switch SW (9) is held at the value 1, and step S262 is executed.
Proceed to. In step S262, the short-term counter CNTM
The value of US is incremented to 1. Step S258
If the determination result of is affirmative, the process proceeds to step S260,
The fuzzy input switch SW (9) is reset to the value 0. The fuzzy input switch SW (9) is reset to the value 0 after waiting a predetermined time (20 seconds) from the time when the sum PBM of the detection frequencies becomes smaller than the predetermined value XMU.

When this fuzzy input switch SW (9) is set to the value 1, it means that the vehicle is traveling on a road surface having a small friction coefficient μ. As will be described later in detail, the switch SW (9) is used for gear shift control such as early effecting engine braking when traveling on a downhill and prohibiting a shift change when turning a corner on a curved road. It

Next, proceeding to step S264 in FIG. 17,
Fuzzy input switch SW during the past TMU period
It is determined whether or not the state in which (9) has the value 1 is equal to or greater than a predetermined percentage (for example, 50%). The TMU period is a predetermined time (20
(Seconds), for example 20 minutes. If the determination result of step S264 is affirmative, step S264
In 266, the fuzzy input switch SW (10) which is the long-term low μ road determination flag is set to the value 1, while in the negative case, it is reset to the value 0 in step S268. The value of the fuzzy input switch SW (10) is stored in a non-volatile storage device whose memory is not erased even when the engine is stopped by turning off the key switch, and the value is read when the engine is restarted.

A value of 1 is set to the fuzzy input switch SW (10).
When is set, it is assumed that the outside temperature is low and the road surface is completely frozen. In addition, the shift control is automatically executed in the so-called snow mode to start the second gear. Then, step S
Proceeding to step 270, the fuzzy input switch SW (9) has the value 1
Is set, that is, whether or not it is determined that the road surface is in the low μ state. If this determination is negative, that is, if the road surface condition is normal, the process proceeds to step S272, and the threshold value P6 corresponding to the first α value, for example α = 0.5, is obtained from the engine brake timing map.
Read 1U, P62U, P63U, P82L, P82U and rewrite to these values. On the other hand, if the determination result of step S270 is affirmative, that is, if it is determined that the road surface is in the low μ state, the process proceeds to step S274, and from the engine brake timing map, the second value smaller than the first α value is determined. α
Value, for example, each threshold value P61U, P62U, P63U corresponding to α = 0.1,
Read P82L and P82U and rewrite to these values.

21 (A) and 21 (B) show an example of an engine brake timing map, and thresholds P61U, P62U, used in fuzzy rules 2, 3, 4, 6, 7, and 8 to be described later.
The membership functions that define the relationship between P63U, P82L, P82U (see Tables 5 and 7) and the variable α are shown. All of these threshold values are uniquely set by the same variable α, and when the α value is changed, the threshold values P61U, P62U, P63U, P8 corresponding to the α value are obtained from the map shown in FIG. 21 and a map similar thereto.
Set 2L and P82U respectively. Therefore, if the α value is set corresponding to the road surface μ value, all the threshold values corresponding to the road surface μ can be set. As a result, as will be described later in detail, each membership function value of the fuzzy rule is set to the road surface μ.
Therefore, it is possible to change the timing for applying the engine braking on the downhill according to the road surface μ.

Discrimination of Rule Establishment In the shift control method of the present invention, the following fuzzy rules are identified to be established, and the control mode corresponding to the established rule is selected. Whether or not each fuzzy rule is established requires that all of the following conditions be satisfied. (1) All fuzzy input switches related to the rule are equal to the established value.

(2) All fuzzy input variables involved in the rule are included in the range of the specified membership function. (3) The number of times the rules have been met must be greater than or equal to the specified number of times in a row. Table 4 shows the fuzzy input switches involved in each fuzzy rule and the established values. Table 5 shows the fuzzy input variables involved in each fuzzy rule and the outline of each rule.
The membership function is a crisp set in this embodiment, and fuzzy inference is performed depending on whether the fuzzy input variable value is within a predetermined range value of each membership function.
Table 6 shows the control modes selected when the establishment of each fuzzy rule is confirmed.

[0098]

[Table 4]

[0099]

[Table 5]

[0100]

[Table 6] FIG. 22 shows a procedure for discriminating the establishment of the above-mentioned fuzzy rule. First, in the rule conformity discrimination routine, it is discriminated whether or not each rule conforms to each rule, and then, the routine for checking the conformed rule. In, it is confirmed that the number of matching times of the matched rule is a predetermined number of times or more in succession.

FIG. 23 shows a more specific procedure for determining rule conformity. When this routine is executed, the electronic control unit 5 first resets the program control variable n to the value 0 in step S120. Then, it is determined whether or not all the fuzzy input switches of rule n are suitable (step S121). For example, in Rule 0, Table 4
Therefore, it is determined whether or not the fuzzy input switch SW (1) is equal to the established value 1. For example, in rule 8, it is determined whether or not the fuzzy input switch SW (0) and the fuzzy input switch SW (4) are equal to the established values 2 and 1, respectively, and it is determined whether or not they are all established. become.

In step S121, if even one of all the fuzzy input switches related to the rule n is not suitable, the process proceeds to step S123 and the control variable TEK is entered.
Set the value 0 to I (n). On the other hand, step S121
In, if all the fuzzy input switches related to the rule n are matched, the process proceeds to step S122, and this time, if all the fuzzy input variables related to the rule n are matched, that is, the fuzzy input variables are designated. It is determined whether the membership function is included in a predetermined range.

For example, as shown in Table 5, rule 0
In 5, the matching of 5 fuzzy input variables is determined, and in Rule 4, the matching of 4 fuzzy input variables is determined. The fuzzy input variable FV (0) is small, that is, the proposition of whether or not the vehicle speed is small is that the fuzzy input variable FV (0) is calculated from the 0th membership function prepared corresponding to this fuzzy input variable. Within a predetermined upper and lower limit range (for example, 10 km / h
It is inferred depending on whether the value is r or more and within a range of 55 km / hr or less). Similarly, fuzzy input variable F
The proposition of whether V (0) is medium, that is, the vehicle speed is medium is that the fuzzy input variable FV (0) is a predetermined upper and lower limit from the first membership function prepared corresponding to this fuzzy input variable. Within the value range (for example, 30 km / hr or more, and 1
It is inferred depending on whether the value is within the range of 00 km / hr or less). Table 7 shows the relationship between such propositions and membership functions.

[0104]

[Table 7] If the determination result in step S122 is negative, the process proceeds to step S123 described above, and the control variable TEKI (n)
To the control variable TEKI (n) with a value of 0, while if all the fuzzy input switches of rule n match and all of the fuzzy input variables of rule n match, the control variable TEKI (n) has a value of 1 Is set and the fact that the rule n has been met is stored.

When the conformity determination of one rule is completed, the program control variable n is incremented by 1 in step S126, and then the variable value n is set to the predetermined value CRUL.
It is determined whether or not it is equal to (a value corresponding to the number of rules), and the above step S121 and subsequent steps are repeatedly executed until the variable value n reaches a predetermined value CRUL, and it is determined whether all the rules match. .. When the determination of conformity of all rules is completed and the determination result in step S128 is affirmative, the routine is completed.

Here, the conformity with rules 2 to 4 is a condition for entering the downhill weak engine braking mode 2.
Then, the entry into the mode 2 means that the gear stage is forcibly set to the third gear and the engine braking is activated. Referring to Table 5 and Table 7, in order to comply with the rule 2, the weight gradient resistance FV (6) is negative and the vehicle speed is 2 seconds difference FV.
It indicates that (8) needs to be large. Rule 3
The weight gradient resistance FV (6) is negative, and the weight gradient resistance FV (6) is negative and the vehicle speed 2-second difference FV (8) is large. Indicates that there is.

The conformity with rules 6 to 8 is a condition for entering the downhill strong engine braking mode 3. Then, the entry into the mode 3 means that the shift speed is forcibly set to the second speed and the strong engine braking is applied. It shows that the weight gradient resistance FV (6) must be negative and oversized, and the two-second vehicle speed difference FV (8) must be large for the rule 6 to be met. Rule 7 conforms to the weight gradient resistance FV
The fact that (6) is negative and oversized, and the conformance of Rule 8 indicates that the weight gradient resistance FV (6) must be negative.

As described above, the proposition "whether the weight gradient resistance FV (6) is negative" and the proposition "whether the vehicle speed 2 second difference (acceleration) FV (8) is large" are satisfied. It is determined by determining whether or not the input variable is included in the predetermined range defined by the threshold of the corresponding membership function. Since this threshold value is set according to the road surface μ in the routines shown in FIGS.
When it is determined that the value is low, these rules are easily adapted, and the timing for applying the engine brake is set earlier.

FIG. 24 is a routine for checking whether or not the matched rule is continuously matched for a predetermined number of times. Reset n to the value 0. Next, in step S131, it is determined whether or not the control variable TEKI (n) corresponding to the rule n designated in step S130 has the value 0. If the control variable TEKI (n) has a value of 0 in step S131, it means that the rule n does not match, and the process proceeds to step S132, where the counter C for rule n is used.
NT (n) is reset to the value 0, the value 0 is set to the control variable SRT (n) which stores the establishment of the rule n, and the process proceeds to step S136 described later.

On the other hand, the determination result of step S131 is negative, and the control variable TEKI (n) corresponding to the rule n has the value 0.
If not, the process proceeds to step S133 and the counter value CN
After incrementing T (n) by the value 1, it is determined whether or not the counter value CNT (n) has reached a predetermined value XCMAX (n) set corresponding to the rule n (step S134). . If the counter value CNT (n) has not reached the predetermined value XCMAX (n), the variable value S
The process proceeds to step S136 without changing RT (n).
The predetermined value XCMAX (n) is set to an appropriate value in consideration of the urgency of execution of the control mode, the degree of influence of rule establishment determination due to noise, and the like.

When one matching rule check is completed,
In step S136, the program control variable n is set to the value 1
Variable value n is incremented by a predetermined value CRUL
It is determined whether or not it is equal to (a value corresponding to the number of rules) (step S138), and the above-described steps from step S131 are repeatedly executed until the variable value n reaches a predetermined value CRUL, and all the rules are processed. Check conformance rules. When the matching rule check of all rules is completed and the determination result in step S138 is affirmative, the routine is completed.

In this way, when the control variable TEKI (n) corresponding to the specific rule n is continuously set to the value 1 by repeating the routine, the counter value CNT
(N) is incremented each time the routine is executed, and finally reaches the predetermined value XCMAX (n). If the determination result of step S134 is affirmative,
Step S135 is executed to reset the counter CNT (n) to the value 0 and set the value 1 to the control variable SRT (n) which stores the establishment of the rule n.

Each Mode Processing When the rule established as described above is discriminated, next,
The electronic control unit 5 performs each mode process according to the procedure shown in FIG. More specifically, first, step S140.
At the program variable X, fuzzy input switch S
Set the value of W (0). That is, the current control mode is specified. Then, the processing routine corresponding to the current control mode X is executed (step S142).

Current Mode 0 Processing Routine When the current shift control is performed in the control mode 0 (normal mode 0), the fuzzy shift position SHIFF is set according to the flowcharts of FIGS. 26 and 27. As described above, the control mode 0 sets the shift speed using the normal shift pattern for traveling on a flat road. From this control mode, as shown in FIG.
Transition to mode 1, mode 2, and mode 4 is possible.

The electronic control unit 5 firstly executes step S15.
At 0, the control variable SRT that stores the establishment of the rule
It is determined whether any one of (2), SRT (3) and SRT (4) has the value 1. These variables store the establishment of the rules 2, 3 and 4, respectively, and as shown in Table 6, when any one of these rules is established, the mode 2
Indicates that you should enter. Therefore, step S1
If the determination result in 50 is affirmative, the process proceeds to step S151, the fuzzy input switch SW (0) is set to the value 2, the fuzzy shift position variable SHIFF is set to the value 3, and the routine ends. As described above, the mode 2 is a mode for forcibly descending a downhill while applying the engine brake at the third speed.

Control variables SRT (2), SRT (3), S
If none of RT (4) has the value 1 and the determination result of step S150 is negative, step S152 is executed and one of the variables SRT (0) and SRT (1) has the value 1
Or not. These variables store the establishment of rules 0 and 1, respectively, and as shown in Table 6, if any one of these rules is established, it indicates that the mode 1 should be entered. Therefore, step S15
If the determination result of 2 is affirmative, step S1 of FIG.
Proceeding to 54, the fuzzy input switch SW (0) is set to the value 1. Then, the process proceeds to step S155, and a variable S representing the shift position (calculated shift stage of mode 0) determined by the shift pattern used in mode 0 described above.
It is determined whether or not HIF1 has a value of 4 indicating the fourth speed. If the result of this determination is affirmative, the shift speed is forcibly changed to 3
In order to shift down to the speed, the fuzzy shift position variable SHIFF is set to the value 3 and the routine is finished. On the other hand, if the determination result in step S155 is negative, the process proceeds to step S156, the variable value SHIF1 is set in the fuzzy shift position variable SHIFF, and the routine ends. It should be noted that the mode 1 is an uphill corner mode as shown in FIG. 1, and the shift speed is determined by using a shift pattern in which the range of driving at the 2nd and 3rd speeds described later is widened. 4 when switching from mode 0 to mode 1
When the vehicle is operated in the speed stage, the shift down is forcibly instructed to the 3rd speed stage, and the shift pattern in the normal mode is switched to the shift pattern for the uphill corner mode during the shift operation of this shift down. When the vehicle is operating at a gear other than the fourth gear, the shift pattern is switched while maintaining the gear.

Control variables SRT (0) and SRT (1)
If none of the values is 1 and the determination result of step S152 is negative, the process proceeds to step S160, and the control variable SRT
It is determined whether or not (5) has a value of 1. This variable stores the establishment of the rule 5, and as shown in Table 6, it indicates that the mode 4 should be entered when this rule is established. Therefore, if the determination result of step S160 is affirmative, the process proceeds to step S162, and it is determined whether or not the shift position variable SHIF1 determined by the shift pattern used in mode 0 is the value 4 indicating the fourth speed stage. To do. If the result of this determination is affirmative, the fuzzy input switch SW (0) is set to the value 4 and the fuzzy shift position variable SHIFF is set to the value 3 in order to forcibly shift down by one gear at the current gear position. Is set and the routine ends.

On the other hand, if the decision result in the step S162 is negative, the process advances to a step S165, and it is decided whether or not the shift position variable (mode 0 arithmetic shift stage) SHIF1 is a value 3 indicating the third speed stage. . If the result of this determination is affirmative, the fuzzy input switch SW (0) is set to the value 4 and the fuzzy shift position variable SHIFF is set to the value 2 in order to forcibly shift down the gear to the 2nd speed. Is set and the routine ends. As described above, in the mode 4 which is the straight climbing mode, if the gear set by the shift pattern used in the normal mode 0 is the fourth gear, the third gear is forced, and if the third gear is the third gear, the second gear is forced. To shift down.

On the other hand, if the shift position variable SHIF1 is neither the fourth speed gear nor the third speed gear, the process proceeds to step S168, where the fuzzy input switch SW (0) is held at the value 0 and the fuzzy shift position variable is changed. The value 5 is set in SHIFF and the routine is finished. The fact that the fuzzy shift position variable SHIFF is set to the value 5 means that the gear is shifted to the fifth gear, but since the transmission 3 does not actually have the fifth gear, the fuzzy shift position variable SHIFF is set. The gear shift command by is ignored and the gear shift control by the normal mode 0 is executed.

When the control variable SRT (5) is not the value 1 and the determination result in step S160 is negative, the process proceeds to step S168, and the fuzzy input switch SW
(0) is kept at the value 0 and the fuzzy shift position variable SHIFF is set to the value 5 to set the normal mode 0.
To continue. Current Mode 1 Processing Routine When the current shift control is performed in the control mode 1, the shift speed is set according to the flowcharts of FIGS. 28 and 29. As described above, the control mode 1 sets the shift speed using the shift pattern for the uphill corner mode. From this control mode, as shown in FIG. Transition is possible.

The electronic control unit 5 firstly executes step S17.
At 0, it is determined whether the vehicle speed FV (0) is smaller than a predetermined value CFV0 (for example, 10 km / hr). If the determination result is affirmative, the process proceeds to step S171 to set the fuzzy input switch SW (0) to the value 0, set the fuzzy shift position variable SHIFF to the value 5 and shift to the normal mode 0. When the vehicle speed is low, the normal mode 0 may be unconditionally executed.

If the vehicle speed FV (0) is larger than the predetermined value CFV0 and the result of the determination in step S170 is negative, the process proceeds to step S172, in which the detected vehicle speed V0 and the accelerator are detected using the uphill corner mode shift pattern. The current shift position N depending on the opening (throttle opening) APS
Is calculated. FIG. 30 shows a shift pattern for shifting up from the second speed to the third speed and from the third speed to the fourth speed. When the control mode shifts from the normal mode 0 to the uphill corner mode 1, the upshift is performed. The line is changed as shown by the arrow in the figure, and the operating range at the second speed or the third speed is widened. More specifically, the upshift line (indicated by a solid line) from the 2nd speed to the 3rd speed in the normal mode 0 divides two shift regions by a line having a constant vehicle speed V _230. On the upshift line of the uphill corner mode 1 (shown by a broken line), the vehicle shifts to a constant vehicle speed V ₂₃₁ line higher than the vehicle speed V ₂₃₀ , and the second speed range is expanded. Similarly, in the normal mode 0, the upshift line from the 3rd speed to the 4th speed (indicated by the solid line) divides two shift regions by a line with a constant vehicle speed V _340. In the upshift line 1 (indicated by a broken line), the vehicle moves to a constant vehicle speed V ₃₄₁ line that is higher than the vehicle speed V ₃₄₀ ,
The 3rd gear range has been expanded. The calculation of the shift position N in step S172 is performed using the shift pattern indicated by the broken upshift line in FIG. Further, the manner in which the second speed or the third speed range is expanded by shifting from the normal mode to the uphill corner mode is shown by a shaded area A in FIG.

Next, the electronic control unit 5 calculates the shift position from the detected vehicle speed V0 and accelerator opening (throttle opening) APS using the normal shift pattern of normal mode 0 shown by the solid line in FIG. At this time, it is determined whether or not the shift up from the 2nd speed to the 3rd speed or from the 3rd speed to the 4th speed occurs, and if the shift up occurs, the variable FLGYN is set to the value 1 (step S17).
3). In the speed change control by the mode 1, as described above, the value 1 is set in the fuzzy input switch SW (0), and the fuzzy shift position variable SHIFF is used to forcibly change the speed to the third speed or lower. I have an order. Setting the variable FLGYN to the value 1 is equivalent to setting the variable SH
It indicates that there has been a change in the shift position such that the upshift is executed if there is no command from the IFF. This will be described with reference to FIG. 31. Due to the change of the shift position, a new shift position is surrounded by the normal mode 0 upshift line (solid line) and the mode 1 upshift line (broken line) (region A shown by diagonal lines). It means that you have entered. This shift position shift may be that the driver releases his / her foot from the accelerator petal and the accelerator opening APS becomes small and the vehicle enters the area A, as shown by arrow TR1 in FIG. 31, and is indicated by arrow TR2. As described above, the vehicle speed V0 may increase and enter the area A in some cases.

As described above, the calculation of the shift position N in step S172 and the storage of whether or not the shift up has occurred due to the variable FLGYN in step S173 are the timings at which the control mode 1 is shifted to another mode. This is to select when the vehicle crosses the upshift line. By changing the control mode at such timing, it is possible to prevent the driver from feeling uncomfortable.

Next, in the electronic control unit 5, the fuzzy input switch SW (3) has the value 1 and the steering wheel angle FV
It is determined whether (9) is smaller than the predetermined value CFV9 (for example, 50 °) and the lateral acceleration FV (10) is smaller than the predetermined CFV10 (step S174). That is, it is determined whether or not the climbing slope is completed and the road is not bent. If this determination is negative, the process proceeds to step S180 in FIG. 29 described later.
On the other hand, when the determination result of step S174 is affirmative,
Proceeding to step S175, whether the shift position N obtained by the shift pattern in the uphill corner mode 1 is larger than the fuzzy shift position variable value SHIFT or the flag FLGYN indicating that an upshift has occurred is 1 or not. Determine whether. If any of these determinations is negative, the process proceeds to step S180 described later, and if either one is satisfied, the process proceeds to step S176.

In step S176, control variables SRT (2), SRT (3), SRT for storing the establishment of the rule are stored.
It is determined whether or not any one of (4) has the value 1. As described above, these variables store the establishment of the rules 2, 3 and 4, respectively. As shown in Table 6, if any one of these rules is established, it indicates that the mode 2 should be entered. ing. Therefore, when the determination result of step S176 is affirmative, the process proceeds to step S177, the fuzzy input switch SW (0) is set to the value 2, the fuzzy shift position variable SHIFF is set to the value 3, and the routine ends. To do. As described above, the mode 2 is a mode for forcibly descending the downhill at the third speed.

Control variables SRT (2), SRT (3), S
If none of RT (4) is the value 1 and the determination result of step S176 is negative, step S178 is executed, the fuzzy input switch SW (0) is set to the value 0, and the fuzzy shift position variable SHIFF is set. A value of 5 is set and the routine ends. In this case, the control mode is changed from the uphill corner mode 1 to the normal mode 0.

Steps S174 and S175
Is executed if the result of the determination is negative,
In step S180 of FIG. 29, first, it is determined whether the shift position N calculated in step S172 is 3 or more. If the determination is negative, the process proceeds to step S184 described below, and if the determination is positive, the process proceeds to step S181. In step S181, it is determined whether or not any one of the control variables SRT (2), SRT (3), and SRT (4) has the value 1. As described above, these variables store the establishment of the rules 2, 3 and 4, respectively, and when any one of these rules is established, it indicates that the mode 2 should be entered. Therefore, when both the determination results of step S180 and step S181 are affirmative, the process proceeds to step S182, the fuzzy input switch SW (0) is set to the value 2, and the fuzzy shift position variable SHIFF is set to the value 3. The routine is finished. As a result, the control mode 2 is executed.

Steps S180 and S181
If any one of the determination results is negative, it means that the uphill corner mode 1 is continued, but in this case, in step S184 and step S185, the shift position N is equal to 4 and the variable SRT (0 ) And SRT (1) have a value of 1. The variables SRT (0) and SRT (1) store the establishment of the rules 0 and 1, respectively, as described above.
If any one of these rules is established, it indicates that mode 1 should be executed. The shift position calculated by the shift pattern for uphill corner mode 1 is not in the fourth gear,
Alternatively, if neither of the variables SRT (0) and SRT (1) is the value 1, that is, if the determination result of either step S184 or step S185 is negative, the process proceeds to step S186, and fuzzy shift is performed. The value N is set in the position variable SHIFF and the routine is finished.

The shift position N is 4 and the variable SR
When either one of T (0) and SRT (1) has the value 1, the uphill corner mode shift control is executed again in the same mode 1 to execute the fuzzy shift position variable SHIF.
Set a value of 3 to F and downshift from fourth gear to third gear. When the shift control in the uphill corner mode is executed, the upshift line shifts so that it is difficult to perform the upshift operation when the vehicle enters the corner portion of the uphill road even if the accelerator opening is returned. This will be described with reference to FIG. 31. When the shift control shifts from mode 0 to mode 1,
The shift area indicated by the diagonal line A is enlarged. On an uphill road that bends frequently, the operating line indicated by the driver's accelerator pedal operation and vehicle speed draws a circle, and this circle is shown in FIG.
It often occurs in the hatched area A shown in FIG. As a result,
Even when the uphill curved road is continuous, the number of upshifts executed is reduced and shift hunting is less likely to occur.

Current Mode 2 Processing Routine When the current shift control is performed in the control mode 2, the shift speed is set according to the flowchart of FIG.
As described above, the control mode 2 is a downhill weak engine braking mode in which the vehicle is held down the downhill by holding the third speed. However, depending on how much the accelerator pedal is depressed,
It may shift to the 4th gear. This control mode 2
From, it is possible to shift to mode 0 and mode 3 as shown in FIG.

The electronic control unit 5 firstly carries out step S19.
0, the control variable SRT (9) has the value 1,
The value of the fuzzy input switch SW (5) is 1, and the vehicle speed FV (0) is a predetermined value CFV0 (for example, 10 km.
smaller than / hr), it is determined whether or not any of the following is true. The control variable SRT (9) stores the establishment of rule 9, and as shown in Table 6, indicates that the mode 0 should be entered when this rule 9 is established. The fuzzy input switch SW (5) stores that the accelerator opening is in a large state. Step S190
If any one of the determination conditions is satisfied, step S191 is executed, the fuzzy input switch SW (0) is set to the value 0, and the fuzzy shift position variable SHIFF is set to the value 5.
Is set and the routine ends. In this case, the control mode is shifted from the downhill weak engine braking mode 2 to the normal mode 0.

If the determination result in step S190 is negative, the process proceeds to step S192, and the fuzzy input switch S
W (5) has a value of 1, accelerator opening FV (4) is smaller than a predetermined value CFV43 (for example, 40%), and fuzzy input switch SW (7) has a value of 0. It is determined whether all the conditions are met. As described above, the fuzzy input switch SW (5) stores that the accelerator opening is large. Also,
The fuzzy input switch SW (7) is for setting the value to 1 and storing the state when the accelerator is strongly depressed during engine braking of the third speed. Therefore, when the fuzzy input switch SW (7) is 0, it means that the accelerator has not been depressed strongly. That is, in step S192, the driver's moderate acceleration intention is determined. If the determination result is affirmative, the process proceeds to step S191 described above, and the fuzzy input switch SW
(0) is set to the value 0, and the fuzzy shift position variable SHIFF is set to the value 5 to shift to the normal mode 0. In this case, the shift stage will be determined using the shifted normal mode shift map.
It is held in the third speed or upshifted to the fourth speed depending on the accelerator opening and the vehicle speed. When the vehicle is shifted up to the 4th speed, the accelerator depression amount is small, and a feeling of acceleration suited to the driver's intention to accelerate on a downhill is obtained.

If the determination result of step S192 is negative, the process proceeds to step S193, this time the fuzzy input switch SW (5) has the value 1, and the accelerator opening F
It is determined whether V (4) is larger than the above-mentioned predetermined value CFV43 (40%). This is for determining the driver's intention of strong acceleration. If the determination result is affirmative, step S194 is executed to set the value 1 to the fuzzy input switch SW (7), and the routine ends. In this case, the third speed is maintained, mode 2 shift control is continued, and strong acceleration is performed downhill. Mode 2 is a shift control mode for descending on a gentle slope while applying weak engine braking. When the driver strongly accelerates the vehicle during such driving, it is expected that strong braking will be required when the vehicle enters a corner after that.
The fuzzy input switch SW (7) is used as a flag for instructing a strong engine brake at the time of forced movement after the strong acceleration. That is, by setting the value 1 to the fuzzy input switch SW (7), the fuzzy input switch SW (5) allows the accelerator opening to be in a large state, and the accelerator opening is a predetermined value CFV43 (40%).
Even if it is smaller, the aforementioned step S192
The determination result of No is negative and the shift control in the normal mode 0 in step S191 is not executed. As will be described later, the downhill weak engine brake mode 2 or the downhill strong engine brake mode 3 of the current control mode is performed. Will be executed, and the number of brake operations can be reduced.

If the determination result in step S193 is negative, the control variables SRT (6), SRT (7), SRT (8) that execute step S196 and store the establishment of the rule are stored.
It is determined whether or not any of the above has a value of 1. As described above, these variables memorize the establishment of the rules 6, 7, and 8, respectively, and as shown in Table 6, if any one of these rules is established, it indicates that the mode 3 should be entered. ing. Therefore, when the determination result of step S196 is affirmative, the process proceeds to step S198, the fuzzy input switch SW (0) is set to the value 3, the fuzzy shift position variable SHIFF is set to the value 2, and the routine ends. To do. As described above, the mode 3 is a mode for forcibly descending the downhill at the second speed.

Control variables SRT (6), SRT (7), S
If none of RT (8) is the value 1 and the determination result of step S196 is negative, the routine is ended without doing anything. That is, the shift control of the current control mode 2 is continuously executed, and useless shift changes can be prevented. Current Mode 3 Processing Routine When the current shift control is performed in the control mode 3, the shift speed is set according to the flowchart of FIG.
As described above, the control mode 3 is a downhill strong engine braking mode in which the vehicle descends downhill by holding the second speed. From this control mode 3, as shown in FIG.
Transition to mode 0 and mode 2 is possible.

The electronic control unit 5 firstly executes step S20.
0, the vehicle speed FV (0) is a predetermined value CFV0 (10 km
less than / hr). If the vehicle speed FV (0) is smaller than the predetermined value CFV0, step S2 is unconditionally performed.
01, and set the fuzzy input switch SW (0) to the value 0.
, And fuzzy shift position variable SHIFF
And the value 5 is set to, and the routine ends. in this case,
The control mode is directly changed from the strong downhill engine braking mode 3 to the normal mode 0.

If the determination result in step S200 is negative, the process proceeds to step S202, and the fuzzy input switch S
W (2) has a value of 1 and accelerator opening FV (4)
Is greater than or equal to a predetermined value CFV44 (for example, 3%). As described above, the fuzzy input switch SW (2) stores that the weight / gradient resistance is in the non-negative state. That is, in step S202, it is determined whether or not the accelerator pedal is slightly depressed after returning from the downward slope. If the result of this determination is affirmative, the process proceeds to step S205, and fuzzy The input switch SW (0) is set to the value 2, the fuzzy input switch SW (5) is set to the value 0, and the fuzzy shift position variable SHIFF is set to the value 3 to shift to the downhill weak engine braking mode 2.

If the determination result in step S202 is negative, the process proceeds to step S204, and this time, the fuzzy input switch SW (6) has the value 1, and the accelerator opening F
V (4) is smaller than a predetermined value CFV45 (for example, 40%), and the fuzzy input switch SW (8) has a value 0.
Or not. Fuzzy input switch SW
As described above, (6) is for storing the middle state of the accelerator opening, and the fuzzy input switch SW (8) is for storing a hard depression of the accelerator during the second speed engine braking, as will be described later. Therefore, this determination is for determining the driver's intermediate acceleration intention. If the determination result is affirmative, the process proceeds to step S205 described above, and the fuzzy input switch SW (0) is set to the value 2 and the fuzzy input is set. The input switch SW (5) is set to the value 0, and the fuzzy shift position variable SHIFF is set to the value 3 to shift to the downhill weak engine braking mode 2. That is,
The shift speed is shifted up from the 2nd speed to the 3rd speed, the accelerator depression amount is reduced as compared with the case of the 2nd speed, and an acceleration feeling that suits the driver's intention to accelerate on a downhill is obtained.

If the determination result in step S204 is negative, the fuzzy input switch SW (6) has the value 1,
Moreover, the accelerator opening degree FV (4) is the above-mentioned predetermined value CFV4.
It is determined whether it is larger than 5 (40%). This step is for determining the driver's intention of strong acceleration. If the determination result is affirmative, step S208 is executed to set the value 1 to the fuzzy input switch SW (8), and the routine ends. In this case, the second speed is maintained and the shift control in Mode 3 is continued. This allows
High output can be obtained according to the driver's strong intention to accelerate downhill. Further, the mode 3 is a shift control mode for descending a steep slope while applying strong engine braking. When the driver strongly accelerates the vehicle during such driving, it is expected that strong braking will be required when the vehicle enters a corner after that. Fuzzy input switch SW
(8) is used as a flag for instructing a strong engine brake at the time of forced motion after the strong acceleration. That is, by setting the value 1 to the fuzzy input switch SW (8), the accelerator opening is set to the predetermined value CFV45 (4).
Even if it is in a medium state smaller than 0%), the result of the determination in step S204 described above is negative, and the downhill strong engine brake mode 3, which is the current control mode, is always continued. The strong engine braking due to the second gear will be effective.

When the result of the determination in step S206 is negative, the routine is ended without setting the value 1 to the fuzzy input switch SW (8). In this case, the second speed is maintained, and the shift control in Mode 3 is continued to prevent useless shift changes. Current Mode 4 Processing Routine When the current shift control is performed in the control mode 4, the shift speed is set according to the flowchart of FIG.
As described above, the control mode 4 is the straight uphill mode, and if the shift position set in the shift pattern of the normal mode 0 is the 4th speed, the 3rd speed is used, and if the 3rd speed, the 2nd speed is used. The required driving force is obtained by downshifting each stage. From the control mode 4, as shown in FIG. 1, only the transition to the mode 0 is possible.

The electronic control unit 5 firstly executes step S21.
0, the accelerator opening degree FV (4) is a predetermined value CFV4
It is determined whether it is smaller than 5 (for example, 10%).
If the accelerator opening FV (4) is smaller than the predetermined value CFV45, step S212 is executed to set the fuzzy input switch SW (0) to the value 0 and set the fuzzy shift position variable SHIFF to the value 5. The routine is finished. In this case, the control mode is changed from the straight uphill mode 4 to the normal mode 0.

If the determination result in step S210 is negative, the process proceeds to step S214, and the accelerator opening FV (4)
Is smaller than a predetermined value CFV46 (for example, 25%),
Moreover, the accelerator pedal depression speed FV (5) is a negative predetermined value (-C
It is determined whether it is smaller than FV5). If all the conditions are satisfied at the same time, the process proceeds to the above-mentioned step S212, and the fuzzy input switch SW (0) is set to the value 0 and the fuzzy shift position variable SHIFF is set to the value 5 to shift to the normal mode 0.

If the determination result of step S214 is negative, the routine is terminated without doing anything. In this case, the current control mode 4 is maintained as it is. Shift position output process As described above, when each mode process is completed, a control signal is output to the hydraulic pressure control device 4 this time based on the set shift position. The flowcharts of FIGS. 35 and 36 show the procedure for outputting the shift position control signal. The outline of the output procedure of the shift position control signal according to this flowchart is to output the control signal only when it is necessary to change the current shift position by fuzzy judgment as described above, and As a condition to perform the operation, further, a predetermined time (for example, 0.5 seconds) has elapsed since the previous shift change, the absolute value of the steering wheel angle is below a predetermined value, and the absolute value of the lateral acceleration is below a predetermined value. Therefore, the shift position is not changed unless any one of these conditions is satisfied.

To explain this more specifically, the electronic control unit 5 first determines in step S220 whether the 0.5 second counter value SFLG is greater than 0 or not.
The 0.5-second counter SFLG is a down counter for determining whether or not a predetermined time (0.5 seconds) has elapsed from the time of the previous shift operation, and is reset to the initial value at the time of the shift operation. Therefore, if the determination result in step S220 is affirmative, the predetermined time (0.5 seconds) has not elapsed since the previous shift operation, and in such a case, the counter value SFLG is incremented by 1 in step S221. Decrement and end the routine. Even if a new shift position is set while the counter value SFLG is not counted down to 0, the shift operation to that shift position is not executed.

If the result of the determination in step S220 is negative after the lapse of a predetermined time from the previous shift operation, step S2
In step 22, it is determined whether or not the fuzzy input switch SW (0) has a value other than 0. If the value of the switch SW (0) is 0 other than the value other than 0, it means the shift control by the mode 0, and in this case, the routine is ended without doing anything. In the normal mode 0, since the shift control is a normal shift control, it is not necessary to perform the interrupt shift control based on the fuzzy judgment. As described above, the shift position control signal is generated by the normal shift control program prepared separately. It is output to the control device 4.

If it is determined that the fuzzy input switch SW (0) is a value other than the value 0 and the result of the determination in step S222 is affirmative, the process proceeds to step S224, and the fuzzy shift position SHIFT and the normal mode 0 shift pattern are used. The smaller one of the gear stages SHIF1 to be set is selected, and this is set to the variable N as a shift position command value.
Even during the fuzzy control, the shift stage SHIF1 determined by the shift pattern used in the normal mode 0
Is smaller, that gear is selected preferentially. That is, the shift stage SH in which the fuzzy shift position SHIFF is set from the shift pattern in the normal mode 0
The fuzzy shift position SHIFF is selected only when the speed is lower than IF1. Next, it is determined whether or not the value of the selected shift position command variable N is equal to the gear position SHIF0 currently commanded (step S2).
26). If they are equal, it is not necessary to perform the shift operation, and the routine ends.

On the other hand, if the determination result in step S226 is negative, the shift position command variable N is greater than the current commanded shift stage SHIF0, that is, the absolute value FV (9) of the steering wheel angle is greater than the predetermined value CFV9 at the time of upshifting. Is large and the lateral acceleration absolute value FV (10) is a predetermined value CF.
It is determined whether or not any of the following conditions is satisfied (step S228). If any of the conditions is satisfied, the determination result of step S228 is affirmative, and in this case, the routine is ended without changing the shift position, that is, without performing the gear shift. That is, if a shift-up command is to be issued by the shift position command variable N, is the steering wheel angle larger than a predetermined value,
Alternatively, when the absolute lateral acceleration value is larger than the predetermined value, the shift operation is prohibited.

If none of the conditions in step S228 are satisfied and the result of the determination is negative, the process proceeds to step S229, and if the fuzzy input switch SW (9) has the value 1, the steering wheel angle absolute value FV (9 ) Is larger than a predetermined value CFV9, and the lateral acceleration absolute value FV (10) is larger than a predetermined value CFV10. Fuzzy input switch SW
As described above, (9) is set to the value 1 when it is determined that the friction coefficient μ is low due to the freezing of the road surface or the like. Then, whether the steering wheel absolute value FV (9) is larger than a predetermined value CFV9, and the lateral acceleration absolute value FV
If either of the conditions (10) is greater than the predetermined value CFV10 or is satisfied, it means that the vehicle is turning at a corner. If the determination result of step S229 is affirmative, the routine is terminated and the shift operation by the fuzzy shift control is not executed. That is, on the low μ road, the shift shift is prohibited when turning a corner.

If none of the conditions in step S229 are satisfied and the determination result is negative, step S2 in FIG.
30 is executed. In step S230, whether the shift position command variable N is larger than the current commanded shift speed SHIF0 by one step, that is, the shift position command variable N of this time
Determines whether to shift up to the second speed or more at once. If the shift position command variable N is to be shifted up to two or more speeds at a time, then in step S232, the shift up operation of this time is limited to a gear that is one gear higher than the current commanded gear shift SHIF0. Command variable value N to the value (SHIF0
After resetting to +1), the process proceeds to step S237 described later.

On the other hand, if the determination result in step S230 is negative, the process proceeds to step S234, and this time, the shift position command variable N is smaller than the value one step lower than the current command shift stage SHIF0, that is, the current shift. It is determined by the position command variable N whether or not the gear is to be downshifted in two or more speeds at a time. If the shift position command variable N is to be downshifted in two or more speeds at a time, then in step S236, the shift up operation of this time is limited to a gear position lower by one gear than the current commanded gear position SHIF0. Command variable value N to the value (SHI
After resetting to F0-1), step S23 described later.
Proceed to 7. If the determination result of step S234 is negative, the value of the shift position command variable N is held as it is and the process proceeds to step S237.

In step S237, it is determined whether or not the fuzzy input switch (10) which is the long-term low μ road determination flag is set to the value 1. The value of the fuzzy input switch (10) is stored in the above-mentioned nonvolatile battery backup RAM, and when the value is 1,
This means that the friction coefficient μ is low due to snowfall or freezing on the road surface. Therefore, if the determination result of step S237 is negative, the process directly proceeds to step S240, which will be described later, but if affirmative, the process proceeds to step S238 to determine whether or not the command variable N is equal to the value 1. Then, when the command variable value N is equal to the value 1, that is, when the shift position to be output from now on is the first gear, the routine is terminated and the shift down to the first gear is prohibited. The determination result of step S238 is negative, and the command variable value N
Is not equal to the value 1, there is no particular problem and step S2
Proceed to 40.

Here, the instructed shift stage N is compared with the current shift stage SHIF0 in the above step S226, and only when the result of this comparison is negative, the following step S238.
Is executed. Therefore, in step S238, the event that the commanded shift speed N value is equal to 1 is the current shift speed SHIF.
0 cannot occur except for the second gear. Therefore, on the snowy road (when the condition of SW (10) = 1 is satisfied), for example, even if the first speed is selected from the shift pattern of the normal mode 0 by decreasing the vehicle speed, the step S23 is performed.
As a result of the step S242 not being executed by the determination of 8,
The current shift speed SHIF0, that is, the second speed is maintained, so that downshifting to the first speed is surely prohibited during traveling on a low μ road.

In step S240, the 0.5 second counter S
After resetting the value of FLG to a predetermined value XT1 (value corresponding to 0.5 seconds), step S242 is executed to output a shift position control signal corresponding to the shift position command variable N to the hydraulic pressure control device 4, and Exit the routine. Step S
The shift position control signal output at 240 is based on the fuzzy control, and this signal has a higher priority than the shift position control signal output based on the normal mode 0. An interrupt is executed for it.

Normal Mode Shift Control Next, the shift control procedure in normal mode 0 will be described.
This will be described with reference to the flow chart of the normal mode shift control routine shown in FIGS. 37 to 39. The normal mode shift control routine is executed in a predetermined control cycle when the shift lever switching position detected by the shift position sensor 12 is switched to the drive (D) position. First, in step S280, the electronic control unit 5 determines whether or not the 0.5 second counter value SFLG is greater than 0. The 0.5-second counter SFLG is the same as the counter used in the shift position output routine in fuzzy control, and as described above, the shift operation is prohibited until the predetermined time (0.5 seconds) has elapsed from the time of the previous shift operation. It is for doing. Therefore,
If the determination result in step S280 is affirmative,
If the predetermined time (0.5 seconds) has not elapsed since the previous shift operation, and in such a case, the routine is immediately ended. The counter value SFLG is decremented to the value 1 in the shift position output routine described above.

If the result of the determination in step S280 is negative after the lapse of a predetermined time from the previous shift operation, step S2
81. Vehicle speed FV (0) and accelerator opening FV
(4) is read, the read vehicle speed FV (0) is 0,
Moreover, it is determined whether or not the accelerator opening degree FV (4) is 0 (step S282). This determination is to determine whether the vehicle is stopped and the driver does not step on the accelerator pedal. If the determination result is affirmative, the process proceeds to step S284, the SHIF1 value is compulsorily set to the value 2, that is, the second speed stage, as the command shift stage, and the process proceeds to step S285. As described above, when the shift lever is switched to the D range and the vehicle is stopped, shifting to the second gear can prevent such a creep phenomenon that occurs when the vehicle is stopped.

If the result of the determination in step S282 is negative, that is, if the accelerator pedal is stepped on to start and the vehicle is running, step S283.
And the mode 0 calculation shift stage SHIF corresponding to the vehicle speed FV (0) and the accelerator opening degree FV (4) from the shift pattern of the normal mode 0 stored in the storage device 5C.
Read 1. The shift pattern in normal mode 0 is
The optimum speed range when the vehicle travels on a flat road such as an urban area is defined by the vehicle speed and the accelerator opening.

After calculating the shift stage SHIF1,
In step S285 of FIG. 38, it is determined whether or not the fuzzy input switch SW (0) has the value 0. If the switch SW (0) is a value other than 0, it means fuzzy shift control in a mode other than mode 0. In this case, the routine is ended without doing anything. On the other hand, step S2
If the determination result of 85 is affirmative and the normal mode is 0, the calculated shift stage SHIF1 is the shift stage S currently instructed.
It is determined whether it is equal to HIF0 (step S28).
6). If they are equal, there is no need to perform a shift operation,
The routine is finished.

On the other hand, if the decision result in the step S286 is negative, the process advances to a step S288, and when the fuzzy input switch SW (9) has the value 1, the absolute value FV (9) of the steering wheel angle exceeds the predetermined value CFV9. It is determined whether or not one of the following conditions is satisfied: whether the lateral acceleration absolute value FV (10) is greater than a predetermined value CFV10. As described above, the fuzzy input switch SW (9) is a switch for storing that the friction coefficient μ is low due to the freezing of the road surface or the like, and like the case of the shift position output routine shown in FIG. S288
If the determination result of is positive, the routine is finished and the shift operation by the fuzzy shift control is not executed. That is, on the low μ road, the shift shift is prohibited when turning a corner.

If the determination result in step S288 is negative, step S290 in FIG. 39 is executed. In step S290, whether the mode 0 calculation shift stage SHIF1 is larger than the current command shift stage SHIF0 by one stage or more,
That is, it is determined whether or not the second or more gears will be shifted up at once by the calculated shift stage SHIF1. If the calculated shift stage SHIF1 is to shift up to the second speed or more at a time, step S
In 292, in order to limit the shift-up operation of this time to a speed higher by one than the current commanded speed SHIF0, the calculated speed SHIF1 is set to a value (SHIF0 + 1).
After resetting to, the process proceeds to step S298 described later.

On the other hand, if the determination result in step S290 is negative, the process proceeds to step S294, and this time, the mode 0 calculation shift stage SHIF1 is changed to the current command shift stage SHIF0.
It is determined whether or not the value is smaller by one step lower, that is, whether or not the second or more gears are to be downshifted at once by the current calculation shift stage SHIF1. This time calculation speed SH
If the IF1 is to shift down to the second speed or more at a time, in step S296, the current shift-up operation is performed from the current command shift stage SHIF0 by one.
In order to limit the shift speed to a lower shift speed, the calculation shift speed SHI
After resetting F1 to the value (SHIF0-1), the process proceeds to step S298 described later. If the determination result of step S294 is negative, the value of the calculation shift stage SHIF1 is held as it is and the process proceeds to step S298.

In step S298, it is determined whether or not the fuzzy input switch (10) which is the long-term low μ road determination flag is set to the value 1. The value of the fuzzy input switch (10) is stored in the non-volatile battery backup RAM as described above, and when the value is 1, it indicates that the friction coefficient μ is low due to snowfall or freezing on the road surface. means. Therefore, if the determination result of step S298 is negative, the process directly proceeds to step S302, which will be described later, but if affirmative, the process proceeds to step S300, and it is determined whether or not the calculation shift stage SHIF1 is equal to the value 1. Then, when the calculated shift stage SHIF1 is equal to the value 1, that is, when the shift position to be output from now on is the first shift stage, the routine is ended and the shift down to the first shift stage is prohibited. If the determination result of step S300 is negative and the calculated gear shift stage SHIF1 is not equal to the value 1, there is no particular problem and the process proceeds to step S302.

Considering the case where the shift lever is switched from the N range to the D range and the vehicle starts, in the normal mode shift control applied to this embodiment, the vehicle is stopped and the accelerator pedal is depressed. Unless otherwise, set the shift speed to the 2nd speed forcibly (step S284).
Prevents the creep phenomenon. In this state, when the accelerator pedal is depressed and the accelerator opening degree FV (4) becomes larger than a predetermined minute value, the first gear is selected in step S283. If the shift operation is performed to the first speed at the time of starting, there is no problem on a normal paved road, but on a snowy road, if the accelerator petal is stepped on a detour, the wheels may slip and the starting may be difficult. Even in such a case, according to the gear shift control method of the present invention, in steps S298 and S300 described above, the first speed is prohibited on the low μ road, and therefore, the second speed is set to prevent creep. The speed is maintained as it is, and the second speed is started. Further, it goes without saying that downshifting to the first speed stage is prohibited when traveling on a low μ road. Thus,
On low μ roads such as snow roads, downshifting to the first gear is prohibited to facilitate starting on snow roads and to prevent slipping during traveling.

In step S302, the 0.5 second counter S
After resetting the value of FLG to a predetermined value XT1 (a value corresponding to 0.5 seconds), step S304 is executed to output a shift position control signal corresponding to the calculated shift stage SHIF1 to the hydraulic pressure control device 4 and the routine concerned. To finish. In the above-described embodiment, the shift operation to the lowest speed stage, that is, the first speed stage is prohibited when the vehicle is running on a road surface where the frictional resistance of the road surface is determined to be small or when starting. Depending on the gear ratio, the shift operation to the second gear as well as the first gear may be prohibited.

[0165]

As is apparent from the above description, according to the shift control method for an automatic transmission for a vehicle of the present invention, when it is determined that the frictional resistance of the road surface is small, at least the lowest speed stage is set. Since the shift operation is prohibited, it is possible to prevent the vehicle behavior from becoming unstable due to the change in the driving force, to prevent the slip on a low μ road such as a snow road, and to easily start the vehicle. .

[Brief description of drawings]

FIG. 1 is a diagram showing a mutual relationship between control modes executed by a shift control method for an automatic transmission for a vehicle according to the present invention.

FIG. 2 is a block diagram showing a schematic configuration of a shift control device to which a shift control method for an automatic transmission for a vehicle according to the present invention is applied.

FIG. 3 is a flowchart of a main routine showing a procedure of fuzzy shift control executed by an electronic control unit (ECU) shown in FIG.

FIG. 4 is a steering wheel operation amount FV used for fuzzy shift control.
It is a flowchart which shows the calculation procedure of (2).

FIG. 5: Brake deceleration width FV used for fuzzy shift control
It is a flowchart which shows the calculation procedure of (3).

FIG. 6 is an accelerator depression speed F used for fuzzy shift control
It is a flowchart which shows the calculation procedure of V (5).

FIG. 7: Weight / gradient resistance FV used for fuzzy shift control
It is a flowchart which shows the calculation procedure of (6).

FIG. 8 is a 2-second difference FV of vehicle speed used for fuzzy shift control.
It is a flowchart which shows the calculation procedure of (8).

FIG. 9 is a flowchart showing a setting procedure of a fuzzy input switch SW (1) which is used for fuzzy shift control and which stores a large gradient resistance state.

FIG. 10 is a flowchart showing a setting procedure of a fuzzy input switch SW (2) for storing a gradient resistance non-negative state, which is used for fuzzy shift control.

FIG. 11 is a flowchart showing a setting procedure of a fuzzy input switch SW (3) which is used for fuzzy shift control and stores a gradient resistance non-large state.

FIG. 12 is a part of a flowchart showing a setting procedure of a fuzzy input switch SW (4) which is used for fuzzy shift control and which stores a road folding state.

FIG. 13 is a residual flowchart following the flowchart of FIG. 12;

FIG. 14 is a flowchart showing a setting procedure of a fuzzy input switch SW (5) which is used for fuzzy shift control and which stores a large accelerator opening state.

FIG. 15 is a flowchart showing a procedure for setting a fuzzy input switch SW (6) which is used for fuzzy shift control and which stores an accelerator opening state.

FIG. 16 is a fuzzy input switch SW (9) and SW.
It is a part of the flowchart showing the setting procedure of (10).

FIG. 17 is a residual flowchart following the flowchart of FIG. 16;

FIG. 18 is a diagram showing a relationship between a sideslip angle of a front wheel and its cornering force.

FIG. 19 is a graph showing a cornering force which differs depending on a road surface condition with respect to a skid angle.

FIG. 20 is a histogram of the detected road surface μ as an example.

FIG. 21 illustrates a membership function for simultaneously determining various thresholds according to the α value, and FIG. 21A is a graph showing the relationship between the α value and the weight gradient resistance determination threshold P61U. B) is the α value and the vehicle speed 2 second difference discrimination threshold P82L
It is a graph which shows the relationship with.

FIG. 22 is a flowchart of a rule satisfaction determination routine in fuzzy shift control.

FIG. 23 is a flowchart showing a procedure of rule conformity determination in rule establishment determination.

FIG. 24 is a flowchart showing a procedure of checking a matching rule in rule establishment determination.

FIG. 25 is a flowchart showing a procedure of processing in each mode.

FIG. 26 is a part of a flowchart showing a processing procedure when the current control mode is 0.

27 is a residual flow chart that follows the flow chart of FIG. 26. FIG.

FIG. 28 is a part of a flowchart showing a processing procedure when the current control mode is 1.

FIG. 29 is a residual flowchart following the flowchart of FIG. 28.

FIG. 30 is a graph showing upshift lines in control modes 0 and 1 that divide a shift region according to a throttle opening and a vehicle speed.

FIG. 31 is a graph for explaining a gear shift region that expands with a shift from control mode 0 to control mode 1.

FIG. 32 is a flowchart showing a processing procedure when the current control mode is 2.

FIG. 33 is a flowchart showing a processing procedure when the current control mode is 3.

FIG. 34 is a flowchart showing a processing procedure when the current control mode is 4.

FIG. 35 is a part of a flowchart showing a procedure for outputting a shift position control signal.

FIG. 36 is a residual flow chart that follows the flow chart of FIG. 35.

FIG. 37 is a part of a flowchart showing a shift control procedure in normal mode 0.

38 is a flowchart showing a part of the flowchart subsequent to the flowchart shown in FIG. 37. FIG.

FIG. 39 is a remaining flowchart which follows the flowchart shown in FIG. 38.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Torque converter 3 Gear transmission 4 Actuating hydraulic pressure control device 5 Electronic control unit (ECU) 12 Shift position sensor 16 Brake sensor 18 Wheel speed sensor 20 Engine speed sensor 26 Handle angle sensor 28 Power steering pressure sensor

Claims (1)

[Claims] 1. A shift control method for a vehicle automatic transmission having a plurality of shift speeds including a lowest speed, wherein a parameter value related to a frictional resistance of a road surface is detected, and a parameter value related to the detected frictional resistance is detected. Based on this, when it is determined that the frictional resistance of the road surface is small, at least the shift shift to the lowest speed stage is prohibited, and a shift control method for an automatic transmission for a vehicle.