JP3465357B2 - Control device for automatic transmission for vehicle on downhill road - Google Patents

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.

Furthermore, in JP-A-5-71623 or JP-A-5-71625, when the actual acceleration is larger than the reference acceleration of a flat road by a predetermined value or more, it is determined that the road is a downhill road, and the road is a downhill road. A technique is disclosed in which when the determination is made, the shift characteristic is switched and the engine braking force is increased by downshifting to a lower speed.

[0007]

However, the above-mentioned JP-A-5-71623 or JP-A-5-7162.
In the conventional example such as Japanese Patent No. 5 publication, when determining a downhill road,
The "road surface gradient threshold value" for determining that the vehicle is traveling on a downhill road has the same value in all vehicle speed ranges, that is, the predetermined value has the same value in all vehicle speed ranges.

More specifically, the running resistance due to the vehicle speed is taken into consideration only for obtaining the reference vehicle acceleration (predicted value of running acceleration) even on the flat road, and the downhill road is determined by this. The factor of vehicle speed was not considered at all for the "threshold value of road surface gradient" when doing. Therefore, if the value of the road surface slope that determines that the vehicle is traveling on a downhill road is set to an optimum value in the medium vehicle speed range, low vehicle speed is set.
In the region, engine braking force is increased by downshifting
Is small, and therefore downshift control on downhill roads
Rather than the effect obtained by
It is troublesome to have a gear shift shock (more than necessary)
There was a problem that there was a fear that it would feel strange.

[0009]

The present invention has been made to solve the above-mentioned conventional problems, and an automatic transmission for a vehicle on a downhill road which can realize stable running while avoiding unnecessary downshifts in a low vehicle speed range . An object is to provide a control device.

[0011]

Means for Solving the Problems The present invention provides means for determining whether or not a vehicle is traveling on a downhill having a road gradient of a predetermined value or more, and a downhill road when it is determined that the vehicle is traveling on the downhill. switching suitable shifting characteristics, the control apparatus for a vehicular automatic transmission in which the means for performing transmission control, downhill equipped with in accordance with the switching the shift characteristic, and means for detecting a vehicle speed, a predetermined value, the automatic In the fourth speed running state of the transmission
The above object is achieved by including setting means for setting the vehicle speed in the low vehicle speed range to a larger value than in the medium vehicle speed range.

Further, the present invention provides a means for determining whether or not the vehicle is traveling on a downhill having a road surface gradient of a predetermined value or more, and a shift characteristic suitable for the downhill when it is determined that the vehicle is traveling on the downhill. In the control device for an automatic transmission for a vehicle on a downhill road, the control means for detecting the vehicle speed and the predetermined value are set to exceed the automatic transmission. When driving
The above object is achieved by including setting means for setting a large value in a low vehicle speed range as compared with a medium vehicle speed range.

[0013]

According to the present invention, the gradient threshold value (decision gradient for downhill road: which is a reference when judging whether or not the vehicle is traveling on a downhill road:
(Corresponding to the predetermined value) is changed / set according to the vehicle speed range as shown in FIG.

In FIG. 1, the solid line represents the downhill grade, and the broken line represents the slope at which the acceleration is 0 G at idle-on (accelerator release), that is, the line that balances the vehicle speed and the slope. When the vehicle speed is V, running resistance increases in a high vehicle speed range of V> V2. Therefore, if the set slope (predetermined value) for downhill road determination is set as shown by the alternate long and short dash line in the figure (regardless of vehicle speed V), While decelerating, a region where the engine brake is activated due to downshift (hatched portion in the figure) is generated.

Therefore, in the present invention, as shown in FIG. 1, in the high vehicle speed range (V> V2), the judgment gradient is set to the medium vehicle speed range (V1 <V <
Since it is set to a value larger than V2), it becomes difficult to determine that the gradient exceeds the predetermined value, the frequency of gear shift characteristic switching decreases, and an unexpected downshift for the driver occurs. Can be effectively prevented.

By the way, if this technical idea is uniformly applied to the low vehicle speed region and the control gradient (threshold value) is set as shown by the two-dot chain line in FIG. 1, in the low vehicle speed region (rather than conventional).
The "downhill downshift control" is frequently executed.

However, in the low vehicle speed range, the increase in engine braking force due to the shut down is small. Therefore, the merit due to the execution of the "downhill road downshift control" is not so great from the beginning, and rather, a shift shock that occurs more than necessary may be annoying.

Therefore, in the present invention, in the low vehicle speed range of V <V1, the judgment gradient is set to the medium vehicle speed range (V1 <V <V2).
Since it is set to have a larger value than that of (1), it is possible to avoid the above-mentioned unnecessary downshifting and to realize traveling with less discomfort.

The slope for judging the downhill road is as follows:
As in the embodiment described later, "acceleration equivalent to the gradient" is used, the reference acceleration is used, and the downhill road may be determined by comparing with the actual acceleration calculated from the output of the vehicle speed sensor or the like, Further, in the case where the vehicle is provided with the inclination angle sensor, the gradient itself may be directly used as a threshold. In the case of the present invention, in any case, the "gradient" itself, which is the criterion for the determination, is changed depending on the vehicle speed.

[0020]

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.

A computer 84 for controlling the automatic transmission 2.
Includes a throttle sensor 80 for detecting a throttle opening (corresponding to an accelerator opening) for reflecting the load of the engine 1, a vehicle speed sensor (rotation speed sensor of the output shaft 70) 82 for detecting a vehicle speed, a parking range, a drive. range,
A shift position switch 86 that outputs a signal of a shift position selected by the driver such as the L range, a foot brake switch 88 that outputs a signal when the foot brake is stepped on, an engine speed sensor that detects the engine speed 90, 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), 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 to be selected, a cruise control switch 97 for realizing cruise control (automatic constant vehicle speed travel), and an overdrive off switch 97 for prohibiting travel at overdrive (4th speed). Signal is being input.

The information from 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 (similar to 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 FIG.
According to the control flow as shown in FIG. 5, 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 uphill 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 gear to the third gear 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.

<Control on a Downhill Road> In the control on a downhill road, there are two types of first slope and a 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 so as to have the tendencies shown in FIG. 1 depending on the vehicle speed. That is, in the high vehicle speed range and the low vehicle speed range,
Set the gradient and the second gradient themselves to be large values,
More precise control is performed.

When it is determined that the vehicle 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 descending slope 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 related to the second gradient is executed as follows.

That is, in the state where the accelerator is depressed, 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 with a gentle second gradient), 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, due to 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 to drive 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 related to the second gradient is executed and the gear is downshifted to the third speed again until the fourth speed is upshifted due to 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.

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.

Specifically, the prerequisites are: 1) the vehicle speed sensor 82 of the automatic transmission is normal, 2) the shift position switch 86 is in the drive range, 3) the third speed, Alternatively, one of the fourth speed stages is outputting, 4) the vehicle speed is equal to or higher than a predetermined value and equal to or lower than the 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 climbing and descending slope essential for executing this control is required. 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 less than 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 overrun of the engine.

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, and in order to maintain the vehicle speed constant, a separate gear stage is used in order to keep the vehicle speed constant. Is automatically controlled.

When 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 (the rotation speed sensor of the output shaft 70 of the automatic transmission) 82, and the SBG 43 represents each shift with 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 speed (output shaft speed) is 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. .

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

At step 110, it is judged whether 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 the control flow as shown in FIG.

That is, when the uphill road determination flag F0 is reset to zero in step 108, the flow proceeds to step 1
10, the routine proceeds to step 200, where it is determined in step 200 whether the idle contact switch 92 is on, that is, whether 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 (on the basis of a flat road) because the running resistance is simply increased when the vehicle speed is high. In order to have the tendency shown, that is, the first gradient itself is tighter than when the vehicle speed is in the high vehicle speed range and the low vehicle speed range is in the middle vehicle speed range, the dependence is considered. . As a result, it is easier to determine that the vehicle is traveling downhill at a medium vehicle speed, and the present invention is embodied.

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.

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 the characteristic depending on the vehicle speed as shown in FIG.

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, where it is determined 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 set to be higher in a high vehicle speed range and a low vehicle speed range than in a medium vehicle speed range, as shown in FIG. 1, depending on the vehicle speed (output shaft speed). It is a value (acceleration: positive only) and, as a result, is mapped so as to correspond to a second road surface gradient (second gradient) smaller (slower) than the first gradient.

In this way, SBGE43 or KD
By setting EG as a map based on the vehicle speed or the output shaft speed in consideration of the tendency shown in FIG. 1, it is possible to set the gradient as the threshold value for the determination of the downhill road as intended in the present invention.

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.

In the above 3), the determination of the power-on downshift to the third speed or the output of the third speed after that based on the basic shift map is used as one of the conditions for starting the uphill control, as described above. While the vehicle is traveling in the speed stage, the execution of this control (when the driver does not intend) changes the speed from the fourth speed stage to the third speed stage.
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 the following 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.

When it is determined that the fourth speed step prohibition request flag F2 for the uphill road is 1 even though the uphill road determination flag F0 is zero, the routine proceeds to step 130, where it is counted up from a predetermined time. It is determined whether or not the uphill control return timer has expired. If it has been completed, the fourth speed prohibition request flag F2 for climbing is reset to zero in step 132, but if it has not been completed, step 1
The program proceeds to 42 and again checks the value of the fourth speed gear prohibition request flag F2 for climbing, and when it is 1, the fourth speed gear is prohibited in step 146.

On the other hand, when it is determined that the uphill determination flag F0 is not zero, or even if the flag F0 is determined to be zero, it is determined that the uphill fourth speed prohibition request flag F2 is not 1. If so, the process proceeds to step 134.

At 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 prohibition request flag F3 for downhill is 1 even though the first downhill determination flag F1 is zero, the routine proceeds to step 138, where the flag F1 becomes zero. It is determined whether or not the downhill control return timer to be counted up has expired, and if it has expired, the fourth downshifting stage prohibition request flag F3 for downhill road is reset to zero in step 140.

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.

By the control flow as described above, the control of the ascending / descending road as described above is realized prior to the detailed description of the control flow.

According to this embodiment, as described above, the basic threshold value for determining the downhill road can be set to a relatively large value (first slope), and as a result, the low speed stage is unnecessarily required. It is possible to prevent the control of downshifting to be executed at the same time, and when the foot brake is operated within a predetermined time from the time when the accelerator is released, consider that the driver wants sudden deceleration and Even if the vehicle is traveling on a road having a relatively small road gradient (second gradient), it is possible to reliably shift down to a 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 it is set, it is possible to prevent downshifting to a lower speed stage than necessary at high vehicle speed and low vehicle speed.

Therefore, since the running resistance becomes large, the acceleration itself is small, and therefore, at high vehicle speeds where it is not necessary to perform downhill control so much, and the effect of engine braking is small, so that downhill control is similarly executed. 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, and the driving feeling can be improved accordingly.

[0085]

As described above, according to the present invention, it is possible to effectively prevent the "downshift control on a downhill road" from being performed more than necessary, and to realize running with less discomfort. The effect that can be obtained can be obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a set slope for downhill road determination according to 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.

[Explanation of symbols]

80 ... Throttle sensor 82 ... Vehicle speed sensor (output shaft 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 ... Reference vehicle acceleration (on a flat road) SBGE43 ... Standard vehicle acceleration (downhill)

Front Page Continuation (72) Inventor Yoshiharu Harada 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. (56) References JP-A-5-340469 (JP, A) JP-A-1-116358 (JP, A) JP-A-5-149425 (JP, A) JP-A-63-308258 (JP, A) JP-A-50-74063 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) ) F16H 59/00-61/12 F16H 61/16-61/24 F16H 63/40-63/48

Claims (3)

(57) [Claims] 1. A means for determining whether or not a vehicle is traveling on a downhill road having a road surface gradient of a predetermined value or more, and when it is determined that the vehicle is traveling on the downhill road, a shift characteristic suitable for the downhill road is switched to, A control device for an automatic transmission for a vehicle on a downhill road, comprising: a means for performing a shift control according to a switched shift characteristic; a means for detecting a vehicle speed; and a predetermined value for the fourth speed running state of the automatic transmission. Oke
A control device for an automatic transmission for a vehicle on a downhill road, comprising: a setting means for setting a larger value in a low vehicle speed range than in a medium vehicle speed range. 2. A means for determining whether or not the vehicle is traveling on a downhill road having a road surface gradient equal to or more than a predetermined value, and when it is determined that the vehicle is traveling on the downhill road, a shift characteristic suitable for the downhill road is switched to, A control device for an automatic transmission for a vehicle on a downhill road, comprising: a means for performing a shift control according to a changed shift characteristic; a means for detecting a vehicle speed; and a predetermined value for the overdrive running condition of the automatic transmission.
A control device for an automatic transmission for a vehicle on a downhill road, comprising: a setting means for setting a large value in a low vehicle speed range in a normal state compared to a medium vehicle speed range. 3. Means for determining whether or not the vehicle is traveling downhill
Is the predetermined value when the road surface slope is
Claim to determine whether or not the vehicle is traveling downhill
Item 1. A vehicle automatic transmission control device according to item 1 or 2.