JPH0893903A - Control device for vehicular automatic transmission on downhill road - Google Patents

Abstract

PURPOSE: To improve THE operability by prohibiting shift up to high range gear unrelated to any braking operation when it is particularly required to be decelerated such as sport running while prohibiting high range gear in response to a braking operation of a driver so as to down shift to low range gear in general running on a down hill road. CONSTITUTION: High range gear is prohibited provided that a foot brake is operated and allows the automatic gear changer 2 to be shifted down to a low range gear by an ECU 84 for controlling an automatic gear changer 2 when a road is determined as a down hill road at an accel's stepping in and at high range gear running. While, shift up to a high range gear caused by returning of the accel is prohibited unrelated to operation of a foot brake when an accel is stepped on at running without high range gear and the road is considered as a down hill road at running without high range gear. Whereby, such operations as returning the accel just before a corner and effecting an engine brake are performed without any obstacle.

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 Japanese Patent Laid-Open No. 5-71623, the engine braking force is applied when it is determined that the vehicle is downhill, the accelerator is released, and the foot brake is operated. A technique is disclosed in which the shift map is switched so that the shift down can be performed in order to increase the shift.

[0007]

However, from the above-mentioned Japanese Patent Laid-Open No. 5-71623, generally, "control on a downhill road" generally confirms the driver's intention to decelerate and assists the operation. Since it was executed with the policy, the condition for downshifting to the low speed stage is
As described above, it is determined that the vehicle is on a downhill road, that the accelerator is released, and that the brake is operated. If the running condition meets these three conditions, the low speed However, if one of them does not match, it is not downshifted. That is, conventionally, if it is a downhill road, the downhill control is not immediately entered, but the condition is that the accelerator release and the brake operation are detected, and this is regarded as an expression of the driver's intention to decelerate the downhill road. I was in control. Therefore, there is a problem that the behavior of the vehicle due to the downhill control may not always match the actual driver's request.

[0008] For example, the conventional one matches the driver's sensation in the case of general driving in which the accelerator opening is not large at the time of acceleration on a downhill road and the vehicle travels at a high speed stage. Sometimes did not match the driver's feeling. That is, for example, when exiting a corner in sports driving, it is often attempted to maintain a low speed stage or kick down to accelerate even on a downhill road.

However, in the past, the condition for releasing the accelerator and for operating the brake was to enter the downhill control. Therefore, for example, when the accelerator is returned before the corner, a power-off upshift to a high speed stage occurs, and As a result, the engine braking force was reduced, and the vehicle might not travel in accordance with the deceleration request by the driver for accelerator work.

The present invention has been made in view of such a conventional problem, and extends the concept of the conventional downhill control so that the downhill control can be performed depending on the condition even during non-brake operation. , A control device for an automatic transmission for a vehicle on a downhill road that prohibits shifting up to a high speed stage when the driver really needs engine braking and can travel more in line with the driver's feeling The purpose is to provide.

[0011]

The present invention, as shown in FIG. 1 as its gist, is a means for determining whether or not a vehicle is traveling on a downhill road, and a predetermined means when it is determined that the vehicle is traveling on a downhill road. In a control device for an automatic transmission for a vehicle on a downhill road that prohibits high-speed gears and downshifts to low-speed gears under certain conditions, means for detecting accelerator operation, means for detecting foot brake operation, and If there is a downhill road when traveling at the high speed, a means for prohibiting the high speed and downshifting to the low speed on condition of foot brake operation, and traveling at the time of accelerator depression but not at the high speed When a downhill road is determined at this time, a means for prohibiting upshifting to the high speed stage due to the accelerator being returned regardless of whether or not the footbrake is operated, is provided. Accordingly, those in which the above-described problems.

[0012]

According to the present invention, when it is determined that the vehicle is downhill while the accelerator is being depressed and the vehicle is traveling at a high speed, the high speed is prohibited and the gear is downshifted to the low speed on condition that the foot brake is operated. To

On the other hand, when it is determined that the accelerator pedal is being depressed when the vehicle is not in the high gear and the vehicle is not in the high gear and the vehicle is on a downhill road, the accelerator is returned regardless of whether or not the foot brake is operated and the vehicle is in the high gear. Prohibit shift up.

As a result, in sports running in which acceleration / deceleration is accelerated / decreased by increasing / decreasing the accelerator opening, an operation such as returning the accelerator in front of a corner and applying engine braking can be performed without any trouble. Therefore, in both general driving and sports driving, the downhill control can be matched with the feeling required by the driver.

In other words, conventionally, the driver's intention to decelerate is judged by the accelerator being released and the brake being operated, and the downhill control is entered, but in the present invention, the downhill control is entered. It is intended to extend the judgment to the non-brake operation.

[0016]

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

FIG. 2 is an overall schematic view of an automatic transmission (and engine) for a vehicle 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.
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 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 (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 uphill road.

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

<Control on 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 Downhill Road> In the control on the downhill road, two types of threshold values for the road gradient for determining the “downhill road” are prepared: a relatively large first gradient and a second gradient smaller than this.

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.

When the vehicle is traveling at the third speed, the vehicle is shifted up to the fourth speed as long as the conditions for descending a slope having a slope larger than the first slope, releasing the accelerator, and turning on the foot brake are 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, even when the accelerator is depressed, the determination of the downhill road (related to the second gradient) is always made,
If it is determined to be a downhill road, when the vehicle is traveling in the fourth gear, the accelerator is released next and the foot brake is operated within a predetermined time after the accelerator is released (even if the slope is gentle). Assuming that the driver intends to decelerate, the engine is forcibly downshifted to the third speed where engine braking is stronger than when the vehicle is traveling in the fourth speed.

On the other hand, when the vehicle is traveling in the third speed stage, the high speed stage is prohibited and the third speed stage is held regardless of whether or not the brake is operated when the accelerator is released. As a result,
After all, when the vehicle is traveling at the third speed, the power-off upshift (upshift generated by fully closing the accelerator) is effectively prohibited.

By the way, in the control flow to be described later, when the vehicle is stepping on the accelerator and traveling, the determination of the downhill road is made with this (slow) second gradient as the threshold value. Due to the nature of the conditions, if the judgment gradient is too large like the threshold value of conventional downhill control, it is almost impossible to step on the accelerator on such a downhill road, and this control is actually implemented. This is because there is no opportunity to play. Therefore, when judging the downhill road when depressing the accelerator,
Instead of the "downhill control for deceleration assistance on a tight slope" according to the conventional way of thinking, "to perform the downhill control for sports driving on a downhill road" is executed, so that the second slope is gentler than the first slope. It is judged as a downhill road.

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 off, and 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.

Note that, in 1), the condition that the vehicle speed sensor 82 of the automatic transmission is normal is that the vehicle speed sensor 82 is indispensable for executing this control when the vehicle speed sensor 82 fails. This is because the judgment itself cannot be made.

2) The third drive range in 3)
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 in a separate routine in order to keep the vehicle speed constant when the cruise control is executed. 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 (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 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. .

If it is determined that the vehicle is an uphill road by the above 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.

In 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 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, fourth speed), reference vehicle acceleration for downhill roads (positive and negative) that is pre-mapped with the first road surface slope (first slope) as a reference depending on the vehicle speed for each select pattern
That is.

Further, at step 204, it is judged if the fuel cut (F / C) control of the engine is in operation. If fuel cut control is active, step 2
Go to 06 and reference vehicle acceleration SBGE4 (on map)
A value obtained by subtracting a predetermined value (positive) from 3 is newly defined as the reference vehicle acceleration SBGE43 used in this control. This is because when the fuel cut control is being executed, the engine braking becomes more effective, and it is estimated that the actual acceleration of the vehicle is correspondingly reduced.

At step 208, it is judged if the first descending slope 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
2, the actual vehicle acceleration MOBG calculated from the output of the vehicle speed sensor 82 is the reference vehicle acceleration SBG for the downhill road according to the first slope obtained in step 202 (or 206).
It is determined whether or not it is smaller than E43 by a predetermined time T4 or more. If it is not smaller, it remains as it is (first downhill road determination flag F
The routine proceeds to step 116 (1 remains 1), but when 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.

At 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.

On the other hand, when it is determined in step 200 that the idle contact is not on, that is, when it is determined that the accelerator pedal is being depressed, the routine proceeds to step 216.
The EG's map is searched. This KDEG is a predetermined value (acceleration: positive only) set to be higher depending on the vehicle speed (output shaft rotation speed) when the vehicle speed is in the high vehicle speed range and the low vehicle speed range. And, as a result, a second road gradient (second
It is mapped so as to correspond to (gradient).

In step 218, it is determined whether or not it is determined that the vehicle is descending when the second gradient is used as a threshold, that is, whether the value of the second descending 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.

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 downhill road determination relating to the second gradient is performed only when the idle contact is off 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 satisfied, or one of the third speed outputs after the judgment is satisfied, 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 is to be noted that, in the above 3), the determination of the power-on downshift to the third speed or the subsequent output of the third speed 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. A specific control flow of step 120 is shown in FIG.

That is, first, at step 300, it is judged if the idle contact switch 92 is on.
When the idle contact switch 92 is not on, that is, when the accelerator is being depressed, the routine proceeds to step 301, where the value of the elapsed time t is reset to zero.

In step 300, the idle contact switch 9
When 2 is changed from off to on, a substantial count-up of the elapsed time t is started, and it is determined in step 302 whether the elapsed time t since the idle contact switch 92 is turned on is smaller than the predetermined time t0. It Since it is initially determined to be small, the flow proceeds to step 304, and it is determined whether or not the second downhill road determination flag F10 set in step 220 or 222 is 1. When the flag F10 is 1, the routine proceeds to step 305, where it is judged whether or not it is the fourth speed stage. If it is the fourth speed stage, the following step 306 is executed.
Then, it is determined whether or not the foot brake switch 88 is on, that is, whether or not the foot brake is depressed.

This is because when the vehicle is traveling on the second downhill road at the fourth speed while the accelerator is stepped on, when the brake is operated within a predetermined time after the accelerator is turned off, the fourth This is for prohibiting the speed (third speed downshift).

If it is determined in step 305 that the vehicle is not in the fourth gear, step 306 is bypassed for downhill control regardless of whether or not the brake is operated.

This means that when the vehicle is traveling on the second downhill road at the third speed while the accelerator is stepped on, the fourth speed is set for a predetermined time after the accelerator is turned off regardless of whether or not the brake is operated. This is forbidden (holding at the third speed) to effectively prevent upshifting due to accelerator off (so-called power-off upshifting).

If the flag F10 is zero, the routine proceeds to step 312, where the value of the first downhill road determination flag F1 is checked, and only when F1 = 1, the routine proceeds to step 306, where the foot brake is depressed. It is determined whether or not there is.
Step 1 when the foot brake is depressed
At 22, the fourth downshifting speed prohibition request flag F3 for downhill road is set to 1.

When it is finally determined that the elapsed time t from when the idle contact is turned on has reached the predetermined time t0, the routine proceeds to step 310, where the second descending slope determination flag F10.
Is reset to zero.

When it is determined in step 306 that the foot brake has not been depressed, the process skips step 122 and proceeds to step 126.

Returning again to the control flow of FIG.

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 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 the 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 been completed, the fourth speed step prohibition request flag F2 for uphill road is reset to zero in step 132, but if it has not been completed, the routine proceeds to step 142, and the fourth speed step prohibition request flag for uphill road is executed again. The value of F2 is confirmed, and if it is 1, the fourth speed 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 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, where a reset / count up is performed from a predetermined time. It is determined whether or not the downhill control return timer is finished, and if it is finished, the fourth downshifting 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.

According to this embodiment, as described above, the determination of downhill control (by the second downhill road) is performed even when the accelerator is depressed, and when there is a high demand for deceleration due to accelerator work in sports running on the downhill road. Since the upshift to the high speed stage due to the release of the accelerator is prohibited regardless of whether or not the brake is operated, the downhill control can be matched with the driver's feeling in sports driving. Also, even in the case of general driving, 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,
Even if the vehicle is traveling on a road having a relatively small road gradient, it is possible to surely downshift 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. Moreover, the downhill control based on the same idea as the conventional one can be surely executed (without causing a busy shift) with the first gradient in which the determination gradient is set relatively tight as a reference.

It should be noted that, in the above-mentioned embodiment, it is said that "when the vehicle is traveling in the third gear with the accelerator depressed, the shift up due to the accelerator return (regardless of the brake operation) is prevented". The control is executed under the condition that the accelerator is released (YES in step 300), but this control does not necessarily "release" the accelerator.
It is not necessary to return to. For example, instead of confirming whether the accelerator has been released, a step of confirming whether or not the accelerator has been returned to a predetermined value close to release may be provided, or more directly, this time from the previous accelerator opening degree. A step of checking whether or not the accelerator opening becomes smaller may be provided.

[0084]

As described above, according to the present invention, in general traveling on a downhill road, in response to the brake operation of the driver, the high speed stage is prohibited and the down shift is made to the low speed stage.
In addition, when there is a high demand for deceleration due to accelerator work in sports driving on downhill roads, shifting up to a high speed stage by returning the accelerator regardless of whether or not the brake is operated is prohibited. In the case of, the downhill control can be matched with the driver's feeling.

[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 flowchart showing details of step 120 in 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)

Claims (1)

[Claims] 1. A means for determining whether or not a vehicle is traveling on a downhill road,
When it is determined that the vehicle is traveling on a downhill road, a means for detecting an accelerator operation in a control device for a vehicle automatic transmission on a downhill road that prohibits a high speed stage and downshifts to a low speed stage under a predetermined condition, A means for detecting a footbrake operation, and a means for prohibiting the high speed step and downshifting to the low speed step on the condition that the footbrake operation is performed when the downhill road is judged when the accelerator pedal is depressed and the high speed step is performed. And a means for prohibiting the shift-up to the high speed stage due to the accelerator being released regardless of whether or not the foot brake is operated when the downhill road is judged when the accelerator is depressed and the vehicle is not in the high speed stage. A control device for an automatic transmission for a vehicle on a downhill road, comprising: