JPH0893909A - Automatic transmission controller for vehicle on uphill road - Google Patents

Abstract

PURPOSE: To prevent the worsening of the fuel consumption in the shift to the low speed stage by judging whether or not the traveling on the low speed stage after the inhibition of the traveling on the high speed stage improves the efficiency of a torque converter to perform the down shift concerning the control on an uphill road in the shift to the low speed stage on the basis of the result of the judgement. CONSTITUTION: While the efficiency of a torque converter 20 is represented as the function of a speed ratio e (= turbine rotational speed Nt/engine rotational speed Ne) with an almost rightward rising property, the property is lowered once right before it enters the fluid coupling region and then rises rightward again. Thus, whether or not the downshift to the low speed stage improves the efficiency can be perceived by observing the degree of the speed ratio e. Then when the present speed ratio e is low and thereby the efficiency ηof the torque converter 20 is also low in an ECU 84, an automatic transmission 2 is controllably shifted down to the low speed stage to lessen the slip ratio and improve the efficiency.

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 an uphill 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 Japanese Patent Publication No. 59-8698, the reference vehicle acceleration (predicted acceleration) on a flat road is obtained in advance using the throttle opening, the vehicle speed, etc. as parameters.
The reference vehicle acceleration is compared with the actual vehicle acceleration calculated from the vehicle speed. When the actual acceleration is greater than the reference vehicle acceleration by a predetermined value or more, the vehicle is traveling downhill, and when it is smaller, it is traveling uphill. The technology for judging is also disclosed.

When it is judged that the vehicle is traveling on an uphill or downhill road, in general, in order to improve the power performance in the uphill road and in order to apply the engine braking more in the downhill road, both are generally used. Control for maintaining or downshifting to the low speed stage side is performed.

[0007]

However, if the high-speed gear is prohibited and the gear is downshifted to the low-speed gear when it is determined to be an uphill road, there is a possibility that the fuel efficiency is generally deteriorated due to an increase in the gear ratio. In addition, the downshift may result in an unexpected shift for the driver, which may cause the driver to feel uncomfortable.

In view of the above point, even if it is determined that the vehicle is an uphill road, the vehicle does not immediately downshift, but waits until the time when the vehicle should be downshifted by crossing the downshift line on the normal shift map, and synchronizing with this. It is conceivable that a configuration is adopted in which the gears are downshifted, and after the downshift is performed once, the low speed stage is maintained even when the upshift line is next crossed on the shift map.

However, even if it is judged that the vehicle is traveling uphill in this way even if it is judged to be an uphill road, its actual execution is retained, so that fuel consumption will be reduced even if the actual traveling state shifts to the low speed stage. Even if the shift does not deteriorate so much and the driver does not expect a shift, the downshift is not performed, and the original function of the uphill control is impaired.

The present invention has been made in view of the above conventional problems, and does not cause deterioration of fuel consumption.
Another object of the present invention is to provide a control device for an automatic transmission for a vehicle on an uphill road, which can maximize the original functions of the uphill control while preventing the driver from feeling uncomfortable due to the execution of the uphill control. And

[0011]

The present invention is provided with means for judging whether or not the vehicle is an uphill road, and when it is judged to be an uphill road,
In a control device for an automatic transmission for a vehicle on an uphill road in which a high-speed gear is prohibited and a down-shift is performed to a low-speed gear under a predetermined condition, when the low-speed gear travels more automatically Efficiency determining means for determining whether or not the vehicle is in a traveling state in which the efficiency of the torque converter of the machine is improved, and it is determined that the vehicle is traveling on an uphill road, and traveling at the low speed stage is better than traveling at the high speed stage. Means for prohibiting the high speed stage and downshifting to the low speed stage when it is determined that the vehicle is in a traveling state in which the efficiency of the torque converter is improved are provided to solve the above problems.

When it is determined that the speed ratio of the torque converter is less than or equal to a predetermined value, it is a running state in which the efficiency of the torque converter is improved by prohibiting running at the high speed stage and running at the low speed stage. If the determination is made, the efficiency of the torque converter is directly determined from the speed ratio of the torque converter, so that the running state described above can be accurately determined.

Further, a reference vehicle acceleration (expected acceleration) on a flat road is obtained on the basis of the throttle opening, the vehicle speed and the shift stage, and when it is judged that this is a predetermined value or more, the high speed stage is prohibited and the low speed is lowered. When it is determined that the vehicle is in a traveling state in which the efficiency of the torque converter is improved when traveling in multiple steps, the above-described traveling state is achieved by using the expected acceleration that has already been obtained to determine the “uphill road”. Since it becomes possible to determine whether or not it is possible to further simplify the control.

[0014]

In general, the efficiency of the torque converter depends on the speed ratio e
It is known that the characteristic becomes approximately upper right as a function of (= turbine rotation speed Nt / engine rotation speed Ne).
However, the way to the upper right is not linear, and as shown in FIG. 6, after rising relatively rapidly from zero, the degree of increase gradually becomes gentle, and after a slight decrease to the right, The characteristic is that it goes up to the right again when it enters the fluid coupling area.

Therefore, by seeing how much the current speed ratio e of the torque converter is, it is possible to know whether or not the efficiency is improved by downshifting to the low speed stage.

For example, when the current speed ratio e is low and therefore the efficiency η of the torque converter is also low, the efficiency η is increased by downshifting to a lower speed stage to reduce the slip ratio and increasing the speed ratio. be able to. As a result, even if the gear ratio is increased by downshifting to the low speed stage, the fuel economy does not deteriorate so much, but in some cases it may rather improve.

On the other hand, if the current speed ratio e is already considerably high, the efficiency η may rather decrease even if the speed ratio e is further increased by downshifting to the low speed stage. Deterioration of fuel efficiency due to the increase in the ratio becomes remarkable.

In view of this point, the present invention judges whether or not the traveling state in which the efficiency of the torque converter is improved by prohibiting traveling at the high speed stage and traveling at the low speed stage, and based on this, The downshift related to the uphill road control is executed. As a result, even if shifting to the low speed stage, the fuel consumption does not have to be deteriorated so much, and in some cases, the fuel consumption can be improved.

Further, in such a traveling state, it is similar to the traveling state in which a downshift command is issued on the shift map, and it is considered that the driver does not feel uncomfortable.

The speed ratio e of the torque converter is determined by whether or not the vehicle is in a traveling state in which the efficiency of the torque converter is improved.
If it is directly determined from, it is possible to determine the traveling state described above very accurately.

Further, whether or not the vehicle is in a traveling state in which the efficiency of the torque converter is improved is determined based on whether the reference vehicle acceleration (expected acceleration) on a flat road, which is determined based on the engine load, the vehicle speed, and the gear position, is a predetermined value or more. If the determination is made by using the or, the expected acceleration is originally obtained already for the determination of the uphill road, and therefore the control can be simplified accordingly.

[0022]

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.

This automatic transmission 2 includes a torque converter 2
0, overdrive mechanism 40, forward 3 speeds reverse 1
And a stepped underdrive mechanism portion 60.

The torque converter 20 includes the 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. , The 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 with emphasis on fuel efficiency (normal pattern). Pattern select switch 94, a turbine rotation speed sensor 97 for detecting the rotation speed of the turbine 22 of the torque converter 20, an overdrive (fourth
Signals for various controls such as an overdrive off switch 97 for prohibiting traveling at a high speed are 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 first described.

<Control on an Uphill Road> When it is determined that the vehicle is traveling on an uphill road, in consideration of the efficiency η of the torque converter 20, traveling at the fourth speed is prohibited and downshifting to the third speed is performed. Further, shifting up from the third gear to the fourth gear is prohibited, and the third gear is held (even if it is determined on the basic shift map that the gear should be shifted to the fourth gear). It The main purpose is to secure power performance and prevent deterioration of fuel efficiency.

The climbing control is restored immediately or after a predetermined restoration timer (delay time) has elapsed depending on the conditions.

<Control on Downhill Road> In the control on the downhill road, the following control is executed.

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

When the vehicle is traveling at the third speed, shifting up to the fourth speed is prohibited (even if it is determined on the basic shift map that the shift to the fourth speed should be made. Also, the third speed is held.

The downhill control is restored immediately or after a predetermined restoration timer (delay time) has elapsed, depending on the conditions.

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, and 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 state in which the cruise control (automatic constant speed traveling control) is not executed 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, it is essential 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 this control is executed only in the hold or downshift at 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 (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 originally no room for holding or downshifting in the third speed and the fourth speed by control.

In 6), the condition that the cruise control is in the inactive state 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 prerequisites are satisfied, the flow proceeds to step 104. In step 104, 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 indicates 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 SBG 43 indicates each shift using the throttle opening and the vehicle speed as parameters. Gear (3rd gear,
4 shows the reference vehicle acceleration (predicted acceleration) during flat road traveling, which is mapped in advance for each fourth speed stage. This SBG43
Is larger when the throttle opening is larger and smaller when the vehicle speed is higher, and is set to be larger for the third speed and the fourth speed in general. Depending on the MOBG and SBG43 co-conditions, it may be positive or negative. Also, KDGS
F is a predetermined value (only positive) that is mapped in advance so as to be constant up to a medium vehicle speed depending on the vehicle speed and increase at a high vehicle speed, K
The DGSN is a predetermined value (only positive) that is previously mapped so as to increase at high vehicle speed depending on the vehicle speed for each select pattern (power pattern, normal pattern) by the pattern select switch 94.

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. When the third speed is maintained longer, the busy shift is prevented, and the acceleration and the engine braking effect are improved, and the vehicle can be 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 Fg0 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 Fg0
Is reset to zero.

When the uphill road determination flag Fg0 changes from 1 to 0, the uphill control return timer, which will be described later, starts counting up.

In step 110, it is judged whether the road 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.

Specifically, the actual vehicle acceleration MOBG is determined from the reference vehicle acceleration SBGE43 by a predetermined time T to determine the downhill road.
It is judged whether it is 5 or more, and if it is, step 1
At 12, the downhill road determination flag Fg1 is set to 1, and if it is not large, the routine proceeds to step 116 while remaining zero.

Here, the SBGE 43 is a gear (third stage).
It is a reference vehicle acceleration (positive / negative) for a downhill road that is mapped in advance depending on the vehicle speed for each of the selection patterns (speed stage, fourth speed stage).

When the downhill road determination flag Fg1 changes from 1 to 0, the downhill control return timer, which will be described later, starts counting up.

Although not specifically shown in the figure, the determination of the downhill road is stopped while the foot brake switch 88 is on. this is,
This is because when braking is applied, the correspondence between the actual vehicle acceleration MOBG and the reference vehicle speed acceleration SBGE43 is broken, and it becomes difficult to accurately determine the downhill road.

When step 116 is reached in this way,
Here, it is determined whether or not the climbing control start condition is satisfied.

Specifically, the conditions for starting the slope control are shown in FIG.
It is executed based on the control flow as shown in. That is, when step 116 is entered from step 114 (or step 112), it is first determined in step 200 whether or not the output of the shift position switch 86 is in the D range. At step 202, it is judged if the output of the overdrive off switch 97 is off. In step 204, the foot brake switch 8
It is determined whether the output of 8 is off. Further, at step 206, it is judged if the output of the idle contact switch 92 is off.

If even one of these judgments is NO, it is determined that the climbing start condition is not satisfied and the routine proceeds to step 120 (FIG. 4). On the other hand, when all of these four conditions are determined to be YES, the current gear is set to the third speed in steps 208 and 210.
It is determined whether the speed is the fourth speed or the fourth speed, or any other speed. If neither the third speed gear nor the fourth speed gear is set, it is determined that the condition for starting the uphill control is not satisfied, and the routine proceeds to step 120.

On the other hand, if it is either the third speed or the fourth speed, the routine proceeds to step 212, where the threshold value e0 of the speed ratio e of the torque converter 20 is searched by a map. The threshold value e0 is set to a value of the speed ratio e such that the efficiency of the torque converter 20 is improved when traveling at a low speed stage than when traveling at a high speed stage. Specifically, the threshold value e0 is mapped using the vehicle speed and the shift speed as parameters, and is set to a larger value for higher vehicle speeds and a larger value for lower speeds than for higher speeds.

In step 214, the turbine rotation speed N
From t and the engine speed Ne, the current speed ratio e
(= Nt / Ne) is determined, and it is determined whether or not this is smaller than the threshold value e0 determined by the map.

If it is smaller, it is determined in step 216 whether the flag Fg0 is 1, that is, whether it is determined to be an uphill road. If it is 1 (if it is determined to be an uphill road), the step is performed. Proceeding to 118, the flag Fg2 for prohibiting the high speed stage is set to 1 and step 120
Proceed to (Fig. 4).

As a result, when the uphill road determination is established and the speed ratio e of the torque converter is smaller than the threshold value e0, the vehicle is traveling at the fourth speed because traveling at the fourth speed is prohibited. Sometimes, the vehicle is shifted to the third speed, and when traveling at the third speed, the shift up to the fourth speed is prohibited.

The fact that the speed ratio e of the torque converter is smaller than the predetermined value e0 generally corresponds to a steep gradient or a gentle gradient but a large accelerator depression amount. It is very similar to a power-on downshift, and it does not make the driver feel uncomfortable. Further, since the efficiency of the torque converter is higher when traveling in the low speed stage, even if the gear ratio is increased by downshifting to the low speed stage, the fuel economy does not deteriorate so much (or rather, it may improve). is there).

Returning to step 120 of FIG. In step 120 of FIG. 4, it is determined 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 downhill road determination flag Fg1 is set. When all of the conditions 1 are satisfied, it is determined that the downhill control start condition is satisfied, and the routine proceeds to step 122, where the fourth downshift inhibition request flag Fg3 for downhill road is set to 1.

If the downhill start condition is not satisfied, step 122 is bypassed. Therefore, at this time, the fourth downshift prohibition request flag Fg3 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 Fg0 is zero. Further, in step 128, it is determined whether or not the fourth speed step prohibition request flag Fg2 for the uphill road is 1.

When it is determined that the uphill fourth speed prohibition request flag Fg2 is 1 even though the uphill determination flag Fg0 is zero, the routine proceeds to step 130, and the above-described uphill control return timer. Is determined.

If the return timer has expired, step 13
In step 2, the fourth speed step prohibition request flag Fg2 for climbing is reset to zero, but if it is not completed, step 142 (14)
Proceeding to 4), the value of the fourth speed prohibition request flag Fg2, Fg3 for the uphill road or the downhill road is confirmed. If either one is 1, the fourth speed is prohibited in step 146. . If both are zero, the control flow ends without prohibiting the fourth speed.

On the other hand, when it is determined that the uphill determination flag Fg0 is not zero, or even if the flag Fg0 is determined to be zero, it is determined that the uphill fourth speed prohibition request flag Fg2 is not 1. If so, the process proceeds to step 134.

At step 134, the downhill road determination flag Fg1
The value of is determined. Further, in step 136, it is determined whether or not the fourth speed stage prohibition request flag Fg3 for downhill road is 1. If it is determined that the fourth downhill speed prohibition request flag Fg3 for downhill is 1 even though the downhill determination flag Fg1 is zero, the routine proceeds to step 138, where the above-described downhill control return timer ends. It is determined whether or not

If the recovery timer has expired, step 14
At 0, the fourth downhill speed prohibition request flag Fg3 for downhill road is reset to zero.

However, when the downhill road determination flag Fg1 is not zero, or even when the downhill road fourth speed prohibition request flag Fg3 for downhill road is not 1, the downhill control return timer has not expired. If it is determined that step 4 (144) is reached, and if either one of the uphill or downhill fourth speed prohibition request flags Fg2, Fg3 is 1, the fourth speed is reached in step 146. Is prohibited.
If both are zero, the control flow ends without prohibiting the fourth speed.

According to this embodiment, the traveling at the fourth speed is performed under the condition that the efficiency η of the torque converter is better when traveling at the third speed than when traveling at the fourth speed. Prohibited, downshift (or hold) to third gear
Therefore, even if the vehicle is downshifted to the low speed stage, it becomes possible to avoid deterioration of fuel efficiency. In addition, since the situation is similar to the situation of crossing the downshift line on the shift map during such traveling, the driver does not feel uncomfortable.

In the above embodiment, step 2 in FIG.
12, 214, a map search is performed for the threshold value e0 of the speed ratio e, and whether the actual speed ratio e is smaller than the threshold value e0 is used to determine whether the vehicle travels in the third speed rather than in the fourth speed. Although it is determined that the vehicle is in a traveling state in which the efficiency η of the torque converter is improved, this is determined by the threshold SBGo4 of the reference vehicle acceleration (estimated acceleration) SBG43.
The value of 3 is map-searched and the reference vehicle acceleration SBG43
By determining whether or not the value of is greater than the map-searched threshold value SBGo43, "the torque converter 22 is more likely to travel in the third speed than in the fourth speed.
May be changed so as to determine that the vehicle is in a traveling state in which the efficiency η is improved.

In this case, the threshold value SBGo43 is mapped using the vehicle speed, the throttle opening, and the shift speed as parameters, and the tendency of increase or decrease is the reference vehicle acceleration S.
It is set in the same manner as BG43. Specifically, the threshold SBGo
43 is smaller when the vehicle speed is higher, and is larger when the throttle opening is larger, and is generally larger in the low speed stage than in the high speed stage.

As a guideline for setting in this case, the reference vehicle acceleration SBG43 obtained from the throttle opening and the vehicle speed when the efficiency η of the torque converter 22 is better to travel at the third speed is a specific value of SBGo43. It will be a value.

As described above, the SBG 43 is used to determine the "running state in which the efficiency of the torque converter is improved when the vehicle runs at the low speed stage while prohibiting the high speed stage".
By using the value of the reference vehicle acceleration SBG43 obtained in step 104 (determination of the uphill road), it is possible to determine one of the conditions for starting the uphill road, so that the speed ratio e is set as in the previous embodiment. Compared with the one obtained directly, the turbine rotation speed sensor is not required and the calculation can be simplified.

[0083]

As described above, according to the present invention,
Since the uphill control is executed after paying attention to the efficiency of the torque converter, it is possible to perform an accurate downshift without deteriorating the fuel consumption and without giving the driver a feeling of discomfort. The effect is obtained.

[Brief description of drawings]

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

FIG. 2 is a schematic diagram of an automatic transmission for a vehicle 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 flow chart showing details of step 116 of FIG.

FIG. 6 is a diagram showing a performance curve of a torque converter of the automatic transmission.

[Explanation of symbols]

 80 ... Throttle sensor 82 ... Vehicle speed sensor (output shaft speed sensor) 84 ... Computer 86 ... Shift position switch 88 ... Foot brake switch 90 ... Engine speed sensor 92 ... Idle contact switch 94 ... Pattern select switch 97 ... Turbine speed sensor MOGB ... actual vehicle acceleration SGB43 ... reference vehicle acceleration (on flat road) SBGE43 ... reference vehicle acceleration (on downhill road)

Claims (3)

[Claims] 1. An automatic gear shift for a vehicle on an uphill road, comprising means for determining whether or not the vehicle is on an uphill road, prohibiting a high speed stage and downshifting to a low speed stage under a predetermined condition when the vehicle is determined to be an uphill road. A control device for the machine, an efficiency determining means for determining whether or not the traveling at the low speed stage is more efficient than the traveling at the low speed stage in the efficiency of the torque converter of the automatic transmission; When it is determined to be a road, and when it is determined that the traveling at the low speed is more efficient than the traveling at the high speed, the torque converter is more efficient, the high speed is prohibited, A control device for an automatic transmission for a vehicle on an uphill road, comprising: means for downshifting to a low speed stage. 2. The torque converter speed ratio according to claim 1, further comprising: a means for determining a speed ratio of the torque converter and a means for determining whether or not the speed ratio of the torque converter is less than or equal to a predetermined value. When it is determined that the vehicle is running on an uphill road, the efficiency determining means determines that the vehicle is traveling at a lower speed than at a high speed so that the torque converter is more efficient. Control device for automatic transmission. 3. An engine load detecting means, a vehicle speed detecting means, a gear position detecting means, and an expected acceleration on a flat road based on the engine load, the vehicle speed and the gear position. When the expected acceleration is determined to be equal to or higher than a predetermined value, the efficiency determining means determines that the speed is lower than that at the high speed stage. A control device for an automatic transmission for a vehicle on an uphill road, characterized in that it is determined that traveling in multiple stages is a traveling state in which the efficiency of the torque converter is improved.