JPH0828694A - Control device of automatic transmission for vehicle on downhill road - Google Patents

Abstract

PURPOSE:To prevent the switching of the downhill control and the normal control more often than required by setting the prescribed delay time when an accelerator pedal is stepped in to release the downhill control during the downhill control to keep an engine brake in a more effective condition. CONSTITUTION:An automatic transmission 2 switches the transmission characteristic by judging whether or not the vehicle is traveling on the downhill road in a computer 84 to input the output signals from a throttle sensor 80, a vehicle speed sensor 82, a foot brake switch 88, etc. When a judgement is made that the vehicle is traveling on the downhill road, the downhill control to set to the transmission step suitable to the downhill road is executed, while when detection is made that an accelerator pedal is stepped in, the downhill control is released after the delay time is elapsed. The delay time is set longer when the accelerator opening is larger than the prescribed value than when it is smaller than the prescribed value. For example, the delay time is set shorter when the accelerator pedal is stepped in when the vehicle turns a corner to realize the sooner returning to the normal control.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an automatic transmission for a vehicle on a downhill road.

[0002]

2. Description of the Related Art Generally, in automatic transmissions for vehicles,
A gear shift map having vehicle speed and engine load (throttle opening degree, etc.) as parameters is provided, and the gear stage to be selected is determined by applying the information of the vehicle speed and engine load at that time during traveling to this gear shift map. .

However, since this shift map is created on the basis of a general flatland traveling state, it does not always give an optimum shift speed when traveling on a downhill road or an uphill road, for example.

In view of such circumstances, for example, Japanese Patent Publication Sho 59
Japanese Unexamined Patent Publication No. -8698 proposes a technique of separately providing a shift map according to a state of a traveling road such as traveling on a flat road and traveling on an uphill road, and appropriately switching these maps for use.

In this Japanese Patent Publication No. 59-8698, a reference vehicle acceleration (expected value of running acceleration) on a flat road is obtained in advance using parameters such as throttle opening and vehicle speed, and the reference vehicle acceleration and the vehicle speed are used. Also disclosed is a technique for comparing the calculated actual vehicle acceleration and determining that the actual acceleration is running on a downhill road when the actual acceleration is greater than a reference acceleration by a predetermined value or more, and the vehicle is traveling on an uphill road when the actual acceleration is smaller than the reference acceleration. Has been done.

Further, in JP-A-1-261545, when it is determined that the vehicle is traveling on a downhill road, a gear stage suitable for the downhill road (specifically, a gear stage where engine braking is more effective) is described. There is disclosed a technique of executing the descending slope control which is performed and canceling the descending slope control after a delay time has elapsed when it is detected that the accelerator is depressed. According to the publication, if the downhill control is released at the moment when the accelerator is stepped on, the upshift may occur at the same time as the delay time is set, and as a result, shock or discomfort may be sensed. It is supposed to be done.

[0007]

Generally, the driver's accelerator work while traveling on a downhill road is as follows: when the accelerator is stepped in order to obtain traction when turning a corner, when the downhill road changes to an uphill road. Therefore, there is a case where the accelerator is depressed to increase the engine output, and a case where the accelerator is depressed for the purpose of acceleration on a downhill road where the visibility is good.

However, the above-mentioned Japanese Patent Laid-Open No. 1-264154.
According to the conventional example according to Japanese Patent Publication No. 5, the downhill control is canceled after a fixed delay time elapses. Therefore, when the delay time is set to be short, the downhill control is easily canceled. There is a problem that a busy shift (frequent shift) occurs. On the other hand, when the delay time is set to be relatively long, there is a problem that the downhill control is released in a delayed manner in the following case.

The present invention has been made in view of such a conventional problem, and more precisely monitors the accelerator work while traveling on a downhill road, so that the downhill control can be truly performed by the driver. An object of the present invention is to provide a control device for an automatic transmission for a vehicle on a downhill road, which can be released so as to match the required traveling mode.

[0010]

SUMMARY OF THE INVENTION As shown in FIG. 1, the present invention is provided with means for judging whether or not a vehicle is traveling on a downhill road and means for detecting the release of an accelerator. When it is determined that the vehicle is traveling, downhill control is performed to set a shift speed suitable for the downhill road, and when the accelerator is detected to be depressed, the downhill control is released after a delay time elapses. In the control device for an automatic transmission for a vehicle in, the means for detecting the accelerator opening, and the delay time,
The above problem is solved by providing a delay time setting means for setting the accelerator opening longer when it is larger than a predetermined value than when it is smaller.

[0011]

In the above case, that is, when the accelerator is depressed to obtain traction when turning a corner,
The accelerator depression is relatively small and the depression time is short. Therefore, even if the delay time is short, the accelerator is likely to be released again within the short time,
If other conditions for downhill control continue to be satisfied at that time, downhill control is continued without any trouble. On the other hand, when the other conditions for the downhill control are not satisfied, the delay time is set to be short and the normal control returns quickly.

Further, in the above case, that is, when the accelerator is stepped on to increase the engine output when shifting from a downhill road to an uphill road, the accelerator pedal is relatively large. Therefore, in setting the delay time, by setting the delay time longer as the accelerator depression is larger, it is possible to determine the condition of the uphill control within the delay time set to this long time, and this is established. If so, it becomes possible to shift from the downhill control to the uphill control as it is without going through the normal control. As a result, busy shift can be prevented.

That is, it is possible to set the delay time appropriately corresponding to the above case, and it is possible to prevent the occurrence of the busy shift and the delay of the release of the downhill control.

Further, even in the case as described above, that is, when the accelerator is stepped on in order to accelerate on a downhill road with good visibility, the accelerator opening is larger when the accelerator opening is larger than when the accelerator opening is smaller than when the accelerator opening is small. Since a qualitatively good result can be obtained when set to be long, the present invention works well even in such a case.

That is, when it is attempted to accelerate slightly from the current state on a downhill road with good visibility, the accelerator is generally depressed to a small degree. In this case, the downshift control has been used to maintain the speed (low speed) where engine braking is more effective.However, as the short delay time elapses, the speed with which engine braking is weak (high speed) )
Will be returned to.

Further, when the accelerator is stepped on a large distance to accelerate more than the current state, a long delay time is set, but when the accelerator is stepped on a large amount to accelerate, the downhill control is originally released. However, it is highly likely that the vehicle will be maintained at the low speed stage, and that maintaining the low speed stage itself matches the driver's intention without any problems. It is possible to prevent re-shift down due to stepping down in a short time, and also to be able to continuously cope with subsequent uphill roads (without going through normal control), so busy shift As a result, good results can be obtained.

When the delay time is set, the factor of vehicle speed is also taken into consideration, and when the vehicle speed is high, the predetermined value (threshold value) of the accelerator opening is set to be larger than that when the vehicle speed is low. Better results are obtained. This is because in general, the higher the vehicle speed, the greater the accelerator pedal depression amount in any of the above cases.

[0018]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 2 is an overall schematic view of a vehicle automatic transmission (and engine) to which the present invention is applied.

The automatic transmission 2 includes a torque converter section 20, an overdrive mechanism section 40, and an underdrive mechanism section 60 having three forward stages and one reverse stage.

The torque converter section 20 includes a pump 2
1, a turbine 22, a stator 23, and a lock-up clutch 24 are well-known, and the output of the crankshaft 10 of the engine 1 is supplied to the overdrive mechanism unit 4.
Transmit to 0.

The overdrive mechanism 40 includes a sun gear 43, a ring gear 44, a planetary pinion 42,
And a set of planetary gears consisting of a carrier 41,
The rotation state of this planetary gear device is controlled by a clutch C0, a brake B0, and a one-way clutch F0.

The underdrive mechanism section 60 is provided with two sets of planetary gear units consisting of a common sun gear 61, ring gears 62 and 63, planetary pinions 64 and 65, and carriers 66 and 67. Rotation state, the overdrive mechanism 40 and the output shaft 70
The connection state with the clutches C1, C2, the brake B1 ~
It is controlled by B3 and one-way clutches F1 and F2.

Computer 84 for controlling the automatic transmission 2
Is a throttle sensor 80 that detects the throttle opening for reflecting the load of the engine 1 or the accelerator opening, a vehicle speed sensor (rotational speed sensor of the output shaft 70) 82 that detects the vehicle speed, a parking range, a drive range, L
A shift position switch 86 that outputs a signal of a shift position selected by a driver such as a range, a foot brake switch 88 that outputs a signal when the foot brake is stepped on, an engine speed sensor 90 that detects an engine speed. , An idle contact switch 92 that outputs the state of the idle contact (ON when the accelerator is released, OFF when the pedal is depressed), and chooses whether to drive with emphasis on power performance (power pattern) or travel with emphasis on fuel efficiency (normal pattern). For various controls such as a pattern select switch 94, a cruise control switch 97 for realizing cruise control (automatic constant vehicle speed traveling), an overdrive off switch 97 for prohibiting traveling in overdrive (4th speed), and the like. A signal is being input.

The information of the vehicle speed sensor 82 is also used to obtain the actual traveling acceleration of the vehicle.

The computer 84 uses the input signals from the respective sensors, switches, etc. as parameters to determine the gear stage to be selected first according to a preset (the same as the conventional) basic shift map of throttle opening-vehicle speed. Then, the solenoid valves S1, S2, S3, S4, etc. in the hydraulic control circuit 98 are driven and controlled so that the shift speed is achieved. As a result, as shown in FIG. 3, the respective clutches, brakes, etc. are engaged or released, and four forward gears (the fourth gear is overdrive) and one reverse gear are achieved.

Here, the computer 84 is shown in FIGS.
According to the control flow as shown in FIG. 6, the special control on the uphill / downhill road is performed according to the traveling state.

FIG. 4 shows a schematic flow of the special control on the ascending / descending road.

In order to facilitate understanding of the control flow, the outline of this special control will be described first.

<Control on an Uphill Road> When it is determined that the vehicle is traveling on an uphill road, it is prohibited to shift down to the third speed and then up to the fourth speed under predetermined conditions. , (Even if it is determined on the basic shift map that the fourth gear should be shifted up), the third gear is held.
The main purpose is to secure power performance and prevent busy shift.

In the case of an uphill road, the forced downshift from the fourth speed stage to the third speed stage is not executed. That is, only when it is determined on the basic shift map that the downshift from the fourth speed to the third speed should be performed, the downshift is performed in synchronization with it. The reason is that there is a risk of discomfort if a downshift is executed at a time when the driver does not expect while the vehicle is stepping on the accelerator.

The uphill control is restored immediately when the preconditions for uphill / downhill control, which will be described later, are not satisfied, but when the uphill condition is not satisfied,
It is performed after the elapse of a predetermined recovery timer.

<Control on a Downhill Road> In the control on a downhill road, there are two types of the first slope and the second slope which are relatively large in the threshold value (predetermined value) of the road surface slope for determining the “downhill road”. Be prepared. Further, both the first gradient and the second gradient are changed / set depending on the vehicle speed. That is, in the high vehicle speed range and the low vehicle speed range, the first gradient and the second gradient themselves are set to have larger values than those in the medium vehicle speed range, and more detailed control is performed.

When it is determined that the road is a "downhill road" with the first gradient as a threshold value, the following control is executed.

That is, when the vehicle is traveling at the fourth speed, the gear is downshifted from the fourth speed to the third speed under the conditions of accelerator release and foot brake ON. This is a forced downshift that is not synchronized with the shift determination on the basic shift map, but the driver does not feel uncomfortable because the foot brake is on.

Further, when the vehicle is traveling at the third speed, the vehicle is shifted up to the fourth speed as long as the conditions of the downhill road having a slope larger than the first slope, the accelerator release, and the foot brake on are continuously satisfied. It is prohibited, and the third speed is held (even if it is determined on the basic shift map that the fourth speed should be shifted up). Since the first gradient is set to be relatively large, the frequency with which the control relating to the first gradient is executed is reduced as compared with the conventional case.

On the other hand, the control of the downhill road according to the second gradient is executed as follows.

That is, when the accelerator is stepped on, the fourth
When the accelerator is released and the foot brake is operated within a predetermined time after the accelerator is released while traveling at a high speed,
Assuming that the driver intends to decelerate (even on a gentle slope), the engine is forcibly downshifted to the third speed with stronger engine braking.

By the way, in the control flow to be described later, the downhill road is determined with the second gradient as the threshold value only when the accelerator pedal is depressed and the vehicle is traveling in the fourth gear. This is because, because of the nature of the conditions, it may not be enough to start the downhill road judgment after the accelerator is released, and the other is that the vehicle runs at the fourth speed when the accelerator is depressed. This is because the control (shift down) related to the second gradient is executed only when the above-mentioned situation has occurred. That is, when the vehicle is traveling in the third gear when the accelerator is depressed and the gear is upshifted to the fourth gear when the accelerator is released, it is not possible to return to the third gear again by the control according to the second gradient. do not do.

The reason for this is that the control relating to the second gradient is executed and the shift down to the third speed is performed again until the fourth speed is upshifted with the release of the accelerator. In this case, when the driver repeatedly depresses the accelerator, releases the pedal, and repeatedly operates the foot brake on a gentle downhill road, the gear shift is executed very frequently, and the time for traveling in the third speed (low speed) is increased. This is because it becomes longer than necessary and fuel efficiency deteriorates.

Therefore, for the same reason, in the case of the control of the downhill road with the second gradient as the threshold value, the control of holding at the third speed is not executed. Therefore, upshifting from the third speed stage to the fourth speed stage can be carried out freely as the basic shift map is changed.

As a general rule, the return of the downhill control is immediately performed when the above-described conditions for the uphill / downhill control which will be described later are not satisfied, but when the conditions for the downhill road are not satisfied, after a predetermined return timer has elapsed. Done.

The timer value of the return timer depends on the accelerator opening (corresponding to the throttle degree), and when the accelerator opening is smaller than a predetermined threshold value θa, it is relatively short t.
When it is larger than 0 and the threshold value θa, it is set to t1 which is longer than this.

Thus, for example, when the accelerator is depressed to obtain traction when turning a corner, the amount of depression of the accelerator is generally small, so the return timer is set to a short t0. As a result, as described above, the cancellation and the continuation of the downhill control are rationally selected.

In addition, when the accelerator is stepped on when going from a downhill road to an uphill road, since the amount of accelerator depression is generally large, the reset timer is set to a long time t1. As a result, it is possible to continuously shift from the downhill control to the direct uphill control without any trouble without causing a busy shift.

Further, even when the accelerator is depressed to accelerate on a downhill road with good visibility, a short timer t0 is set when the accelerator depression amount is small, and a long timer t1 is set when the accelerator depression amount is large. Therefore, as described above, a qualitatively good result can be obtained.

When it is detected that the foot brake switch 88 is turned on, that is, the foot brake is depressed while the t0 timer set when the accelerator opening is small is operating, the t0 timer is set. The counter is cleared, and the count-up is restarted with the time point when the foot brake switch 88 is switched from ON to OFF again as a base point.

The control flow for executing the above-described uphill / downhill control will be described below with reference to FIG.

When this control flow starts, first,
In step 102, it is determined whether or not a precondition for executing the main uphill / downhill control is satisfied.

This precondition is common to the uphill road and the downhill road. Specifically, 1) the vehicle speed sensor 82 of the automatic transmission is normal, and 2) the shift position switch 86 is set to the drive range. 3) Either the third speed or the fourth speed is being output, 4) The vehicle speed is equal to or higher than a predetermined value and equal to or lower than a predetermined value, for example, 1
Within the range of 5 km / h to 125 km / h, 5) Overdrive off switch 97 is off (non-acting), that is, overdrive (4th speed) is in a permissible state, 6) The cruise control switch 96 is turned off, specifically, the cruise non-control state is continuously detected for a predetermined time T1 or more.

If any one of these conditions is not satisfied, the routine proceeds to step 124, where each flag is reset to zero. As a result, the control flow of FIG. 4 is substantially ended.

In 1), the condition that the vehicle speed sensor 82 of the automatic transmission is normal is that when the vehicle speed sensor 82 is failing, the vehicle is required to climb up and down the slope in order to execute this control. This is because the judgment itself cannot be made.

In 2) and 3), the third drive range
The condition that either the first speed or the fourth speed is being output is that the present control is executed only for holding or downshifting in the third speed and the fourth speed of the drive range. This is because.

In 4), the condition that the vehicle speed is within the predetermined value is that the second speed or the first speed is outside the applicable range of this control when the vehicle speed is below the predetermined value. This is because when the vehicle is in a state where the vehicle should enter and when the vehicle speed is equal to or higher than the predetermined value, the vehicle should be maintained at the fourth speed to prevent engine overrun.

In 5), the condition that the overdrive off switch is in the non-acting state is set as a condition when the driver intentionally avoids traveling in the overdrive (4th speed). This is because there is no room for holding or downshifting in the third speed and the fourth speed by the control.

In 6), the condition that the cruise control is inactive is that the cruise control is executed. When the cruise control is executed, a gear shift stage is executed in a separate routine in order to keep the vehicle speed constant. Is automatically controlled.

If it is determined in step 102 that all the preconditions are satisfied, the flow proceeds to step 104. In step 104, first, it is determined whether or not the uphill road determination condition is satisfied. In this case, some hysteresis is provided between when the non-uphill road is determined to be an uphill road and when the uphill road is determined to be a non-uphill road.

Specifically, MOBG≤SBG43-KD
When it is determined that the GSF has been established for a predetermined time T2 or more, it is determined that the vehicle is approaching an uphill road from a non-uphill road. On the other hand, when MOBG> SBG43-KDGSN, the predetermined time T3
When it is determined that the above conditions are satisfied, it is determined that the vehicle has changed from an uphill road to a non-uphill road.

Here, MOBG represents the actual acceleration of the vehicle calculated from the output of the vehicle speed sensor (rotational speed sensor of the output shaft 70 of the automatic transmission) 82, and the SBG 43 represents each shift using the throttle opening and the vehicle speed as parameters. Gear (3rd gear,
4 shows the reference vehicle acceleration during flat road traveling, which is mapped in advance for each fourth speed stage. Depending on both conditions, it may be positive or negative. Further, KDGSF is a predetermined value (only positive) which is previously mapped so as to be constant up to a medium vehicle speed depending on the vehicle speed and increase at a high vehicle speed, and KDGSN is a select pattern (power pattern, normal pattern) by the pattern select switch 94. ) Is also a predetermined value (only positive) that is previously mapped so as to increase at a high vehicle speed depending on the vehicle speed.

When the vehicle speeds (output shaft speeds) are the same, KDGSF> KDGSN (normal)> KDGSN
It is set to be (power). The reason why KDGSF is set larger than KDGSN is to give a hysteresis to the judgment, and KDGSF is set to K rather than KDGSN (power).
The DGSN (normal) is set to be larger because it is more difficult to judge that the uphill road has changed to the non-uphill road in the power pattern than in the normal pattern. This is because the state of is maintained for a long time. If the third speed is maintained for a longer period of time, the fuel economy will be slightly reduced, but the busy shift will be prevented and the acceleration and engine braking effectiveness will be improved accordingly, allowing the driver to travel more sensitive to the movement of the accelerator pedal. .

If it is determined that the vehicle is an uphill road by the determination of such conditions, the routine proceeds to step 106, where the uphill road determination flag F0 is set to 1. On the other hand, if it is determined that the vehicle is not an uphill road, the routine proceeds to step 108. Go to the flag F0
Is reset to zero.

At step 110, it is judged whether or not the vehicle is a downhill road. If it is already determined in step 106 that the vehicle is an uphill road, step 110 is bypassed because it is not necessary to determine a downhill road.

The downhill road determination is specifically executed according to a control flow as shown in FIG.

That is, when the uphill road determination flag F0 is set to zero in step 108, the flow proceeds to step 11
Proceeding to 0, specifically, at step 200, it is judged if the idle contact switch 92 is on, that is, if the accelerator is released.

If it is determined that the idle contact is on, then flow proceeds to step 202 where the SBGE 43 map is searched. SBGE43 is a gear position (3rd
(Speed stage, fourth speed stage), depending on the vehicle speed for each select pattern, the reference vehicle acceleration for which the slope threshold value has been corrected for the downhill road, which is mapped in advance using the first road surface slope (first slope) as a reference. (There are positive and negative).

That is, the way in which the SBGE 43 depends on the vehicle speed is not limited to the fact that the predicted acceleration is small (based on a flat road) because the running resistance is simply increased when the vehicle speed is high. The dependence is considered so that the first gradient itself is tighter in the vehicle speed range and the low vehicle speed range than in the middle vehicle speed range. This makes it easier for the vehicle to be determined to be a downhill road at the medium vehicle speed in step 212 or 210.

At step 208, it is judged if the first downhill road judgment flag F1 is zero. When the first downhill road determination flag F1 is 1, that is, when it has been determined that the road is a downhill road having the first slope or more, step 21
Then, it is judged whether the actual vehicle acceleration MOBG calculated from the output of the vehicle speed sensor 82 is smaller than the reference vehicle acceleration SBGE43 for the downhill road according to the first slope obtained in step 202 by a predetermined time T4 or more. It If it is not smaller, it is as it is (the first downhill road determination flag F1 remains 1)
If it is smaller, the routine proceeds to step 114, where the first downhill road determination flag F1 is reset to zero, and then the routine proceeds to step 116.

In step 208, the first downhill road determination flag F
When it is determined that 1 is zero, the routine proceeds to step 210, where the actual vehicle acceleration MOBG is the reference vehicle acceleration SBGE.
43, it is judged whether or not it is longer than the predetermined time T5 or more. If it is larger, the first downhill road determination flag F1 is set to 1 in step 112, and if it is not larger, it remains at step 11
Proceed to 6.

When the first downhill road determination flag changes from 1 to 0, the count-up of a reset timer t described later is started.

Through the above control flow, the determination of the downhill road with the first gradient as the threshold value is executed. As described above, the first gradient itself already has a characteristic that depends on the vehicle speed.

On the other hand, when it is judged at step 200 that the idle contact is not on, that is, when it is judged that the accelerator is being depressed, the routine proceeds to step 214, at which it is judged whether or not the current actual speed is the fourth speed. Is determined.
If it is the 4th speed, proceed to step 216 and perform KD.
The EG's map is searched. This KDEG is in the high vehicle speed range and the low vehicle speed range so that it has the same tendency as the SBGE 43 depending on the vehicle speed (output shaft speed).
Map to correspond to a second road gradient (second gradient) that is a predetermined value (acceleration: positive only) that is set larger than in the middle vehicle speed range, and as a result is smaller (slower) than the first gradient It has been made into.

In this way, SBGE43 or KD
By using EG as a map based on the vehicle speed or the output shaft rotation speed, it is possible to freely change and set the gradient as the threshold value for determining the downhill road depending on the vehicle speed.

In step 218, it is determined whether or not it is determined to be a downhill road when the second gradient is used as a threshold, that is, whether the value of the second downhill road determination flag F10 should be zero or one. It Specifically, when the value of the flag F10 is currently zero, MOBG> SBG43 + KDEG + KD
If GE is satisfied for a predetermined time T6 or more, step 220
The flag F10 is set to 1. When the current flag F10 is 1, MOBG≤SBG43 + KD
When EG is established for a predetermined time T7 or more, step 222
Then, the flag F10 is reset to zero. Where SBG
As described above, 43 is the reference vehicle acceleration on a flat road (and for an uphill road) that is configured by both parameters of the throttle opening and the vehicle speed, and KDGE is a predetermined value (only positive) for giving hysteresis. is there.

On the other hand, when it is determined in step 214 that the current gear is not the fourth gear, that is, the third gear, the routine proceeds directly to step 222, where the second downhill road determination flag F10 is zero. Is reset to.

The first step in step 110
The processing of the downhill road determination flag F1 is always reset to zero when it is determined that the idle contact is off (regardless of the value of the second downhill road determination flag F10).

The reason why the determination of the downhill road related to the second gradient is made only when the idle contact is off and the vehicle is traveling at the fourth speed is as described above.

Returning to FIG. 4, step 1 is performed in this manner.
When it reaches 16, it is judged here whether or not the slope control start condition is satisfied. Specifically, 1) the foot brake switch 88 is off (the brake is not depressed), 2) the idle contact switch 92 is off (the accelerator is depressed), and 3) to the third gear according to the basic shift map. The condition that the power-on downshift (downshift when the accelerator is depressed) judgment is established, or one of the third speed outputs after the judgment is established, 4) The uphill road determination flag F0 is 1. When all the conditions are satisfied, it is judged that the condition for starting the uphill control is satisfied, and the routine proceeds to step 118, where the fourth speed stage prohibition request flag F2 for the uphill road is set to 1. If any of the climbing control start conditions 1) to 4) is not satisfied, step 118 is bypassed.

It should be noted that, in the above 3), the determination of the power-on downshift to the third speed or the output of the third speed after that is made one of the conditions for starting the uphill control based on the basic shift map, as described above. By executing this control while traveling in the speed stage (when the driver does not intend), the fourth gear position to the third gear position
This is to prevent downshifting to a higher speed. That is, in the uphill control, the positive shift down from the fourth speed to the third speed is not performed, and only the shift up from the third speed to the fourth speed is prevented.

On the other hand, in step 120, it is judged whether or not the downhill control start condition is satisfied.

Specifically, 1) the idle contact switch 92 is on (the accelerator is released), 2) the foot brake switch 88 is on (the brake is depressed), and 3) the first downhill road determination flag. When all the conditions that F1 is 1 are satisfied, or 4) the foot brake switch 88 is turned on (the brake is depressed), and 5) the idle contact switch 92 is turned on within a predetermined time t0. 6) When all the conditions for the second downhill road determination flag F10 to be 1 are satisfied, it is determined that the downhill control start condition is satisfied, and the routine proceeds to step 122, where the fourth downhill speed prohibition request flag F3 for downhill road is set. Set to 1.

If the downhill start condition is not satisfied, step 122 is bypassed. Therefore, at this time, the fourth speed stage prohibition request flag F3 for downhill road is not set to "1".

When step 126 is reached in this way,
After that, the actual processing is performed based on the value of each flag.
First, at step 126, it is judged if the uphill judgment flag F0 is zero. Further, at step 128, it is judged whether or not the fourth speed step prohibition request flag F2 for the uphill road is 1.

If it is determined that the uphill fourth speed prohibition request flag F2 is 1 even though the uphill determination flag F0 is zero, the routine proceeds to step 130, where reset / reset is performed at a predetermined time. It is determined whether or not the uphill control return timer to be counted up has expired. If it has ended, the fourth speed prohibition request flag F2 for climbing is reset to zero in step 132, but if it has not ended, the routine proceeds to step 142, where the fourth speed prohibition request flag F2 for climbing is set again. The value is confirmed, and if it is 1, the fourth speed is prohibited in step 146.

On the other hand, when it is judged that the uphill judgment flag F0 is not zero, or even if it is judged that the flag F0 is zero, it is judged that the fourth speed prohibition request flag F2 for uphill is not one. If so, the process proceeds to step 134.

In step 134, the value of the first downhill road determination flag F1 is determined. Further, at step 136, it is judged if the fourth downshifting prohibition request flag F3 for downhill is 1 or not. When it is determined that the fourth downhill speed prohibition request flag F3 for downhill is 1 even though the first downhill determination flag F1 is zero, the routine proceeds to step 138, and the downhill control return which will be described later in detail. It is determined whether or not the timer has expired. If the timer has expired, in step 140 the downhill fourth speed inhibition request flag F3 is reset to zero.

However, the first descending slope determination flag F1
Is not zero, or even if it is zero
When the speed prohibition request flag F3 is not 1, and when it is determined that the downhill control return timer has not expired, the routine proceeds to step 142 (144), where the fourth speed for uphill or downhill If either one of the speed prohibition request flags F2 and F3 is 1, the fourth speed is prohibited in step 146. If both are zero, the control flow ends without prohibiting the fourth speed.

Here, more specific processing contents of the control relating to the return timer in steps 138 and 140 will be described with reference to FIG.

When the routine proceeds to step 138, specifically, at step 400, first, the descending slope return mode flag F5 indicating that the descending slope is being restored when the accelerator depression amount is large.
Is determined to be zero. Since it is initially zero, the routine proceeds to step 402, where a map of the threshold value θa of the accelerator opening (throttle opening) when setting the delay time is searched. This map is set in advance so as to increase as the vehicle speed increases, depending on the vehicle speed. Therefore, by applying the current vehicle speed to the map, the threshold value θa of the accelerator opening to be adopted is determined here.

At step 404, it is judged if the accelerator opening degree θ is smaller than the threshold value θa. When it is smaller, the routine proceeds to step 406, where it is determined whether or not the value of the timer t which has already been counted up since the first downhill road determination flag F1 changed from 1 to 0 has reached the short delay time t0. Is determined. If not, the process proceeds to step 142 (see FIG. 4) to continue the downhill control,
When it is determined that the delay time t0 is reached, step 4
At 16, the downhill return mode flag F5 is reset to zero,
In step 140 (see FIG. 4), the fourth speed prohibition request flag F3 for the downhill road is reset to zero.

On the other hand, when it is determined in step 404 that the accelerator opening θ is larger than θa, the flow proceeds to step 410, and the accelerator downhill return mode flag F for large accelerator is used.
5 is set to 1 and the timer t is reset in step 412. That is, the count-up of the timer t is newly started here. After that, the longer delay time t1 is compared with the count value of the timer t in step 414, but it is initially determined that the timer t is smaller, so the routine proceeds to step 142 and the downhill control is continued. It

Once the flag F5 is set to 1, the flow proceeds from step 400 directly to step 414 from the next time, and the timer
It is determined whether the count value of t has reached the (longer) delay time t1. If not, the process proceeds to step 142 to continue the downhill control, but if it is determined that the delay time t1 is reached, the downhill return mode flag F is determined in step 146.
5 is reset to zero, and in step 140, the fourth downshift inhibition request flag F3 for downhill roads is reset as an example.

With the control flow as described above, the control of the downhill road as described above is realized prior to the specific description of the control flow.

According to this embodiment, with respect to the delay time set when the downhill control is released due to the release of the accelerator, the delay time is set short when the depression amount of the accelerator is small and set long when the depression amount is large. Therefore, it is possible to effectively prevent the downhill control and the normal control or the uphill control from being repeated more than necessary, and as a result, it is possible to effectively prevent the busy shift from occurring and the downhill control is no longer necessary. In such a situation, it becomes possible to quickly shift to the normal control.

Further, according to this embodiment, as described above, the basic threshold value for judging the downhill road can be set to a relatively large value (first slope), and as a result, it is unnecessary. It is possible to prevent the control to shift down to the low speed stage from being executed, and if the foot brake is operated within a predetermined time from the time when the accelerator is released, it is considered that the driver wants a sudden deceleration. Thus, even when the vehicle is traveling on a road having a relatively small road surface gradient (second gradient), it is possible to surely shift down to the low speed stage. As a result, the true deceleration request of the driver can be reflected in the shift control more than before, and the driving feeling can be improved accordingly.

Further, according to this embodiment, as described above, the first gradient and the second gradient are changed to values larger than those in the medium vehicle speed range in the high vehicle speed range and the low vehicle speed range, respectively.
Since the setting is made, it is possible to prevent the downhill control from entering more than necessary at high vehicle speed and low vehicle speed.

Therefore, the acceleration itself is small due to the increase in the running resistance, and therefore the high down speed control which does not require the execution of the downhill control or the engine braking effect itself is low. Therefore, the downhill control is executed to the same extent. It is possible to prevent the vehicle from being downshifted to an undesirably low speed when the vehicle speed is not required. As a result, the driver's deceleration request can be more appropriately reflected in the shift control than in the conventional case, the busy shift can be prevented, and the driving feeling can be improved.

[0097]

As described above, according to the present invention, the downhill control is released (normal control) under a situation where it is predicted that the traveling state will once again enter downhill control (or uphill control). Return to) can be delayed. As a result, it is possible to effectively prevent the busy shift from occurring due to frequent switching between the downhill control, the normal control and the uphill control.

On the other hand, on the other hand, when it is determined that the running condition no longer requires the downhill control, it is possible to quickly return to the normal control.

[Brief description of drawings]

FIG. 1 is a block diagram showing the gist of the present invention.

FIG. 2 is a skeleton diagram of a vehicle automatic transmission to which the present invention is applied.

FIG. 3 is a diagram showing an operating state of the friction engagement device of the automatic transmission.

FIG. 4 is a flowchart showing a control flow executed in the above embodiment.

5 is a flowchart showing details of step 110 in FIG.

FIG. 6 is a flow chart showing details of step 138 of FIG.

[Explanation of symbols]

 80 ... Throttle sensor 82 ... Vehicle speed sensor (output shaft rotation speed sensor) 84 ... Computer 86 ... Shift position switch 88 ... Foot brake switch 92 ... Idle contact switch 94 ... Pattern select switch MOGB ... Actual vehicle acceleration SGB43 ... (On flat road ) Reference vehicle acceleration SBGE43 ... Reference vehicle acceleration (on a downhill road)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiharu Harada 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd.

Claims (2)

[Claims] 1. A means for determining whether or not a vehicle is traveling on a downhill road,
A means for detecting the release of the accelerator, and when performing the downhill control to make the shift stage suitable for the downhill when it is determined that the vehicle is traveling on the downhill, and when it is detected that the accelerator is stepped on. In a control device for an automatic transmission for a vehicle on a downhill road that releases the downhill control after a delay time has elapsed, a means for detecting an accelerator opening, and the delay time is small when the accelerator opening is larger than a predetermined value. A control device for an automatic transmission for a vehicle on a downhill road, comprising: delay time setting means for setting a longer time; 2. The vehicle according to claim 1, further comprising means for detecting a vehicle speed, wherein the predetermined value of the accelerator opening is set to be larger when the vehicle speed is high than when the vehicle speed is low. Control device for automatic transmission.