JPH08105538A - Speed change control device for automatic transmission - Google Patents

Abstract

PURPOSE: To reduce brake actuation when a vehicle is running on a bad road, and let the vehicle be stably accelerated/decelerated with an accelerator operated by judging whether or not the vehicle is running over a bad road, and prohibiting the vehicle from running by the step of gear shifting for the highest speed in an automatic transmission when it is judged that the vehicle is running on a bad road. CONSTITUTION: Each step of gear shifting of an automatic transmission is selected based on the running condition of a vehicle, so that each speed change operation is thereby executed. In the speed change control device for the kind of this automatic transmission, it is judged by a bad road running judging means whether or not the vehicle is running over a bad road. As a result, when it is judged that the vehicle is running over a bad road, running by the step of gear shifting for the highest speed in the transmission is prohibited by a highest speed step prohibiting means. When it is judged that the vehicle is running over a bad road by the step of gear shifting for the highest speed, down shifting is actuated from the step of gear shifting for the highest speed by the highest speed step prohibiting means in response to brake actuation. Furthermore when it is judged that the vehicle is running over a bad road by each step of gear shifting for low speeds, down shifting is actuated by a low speed shifting means to each step of gear shifting for lower speeds where an engine brake is effective.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift control device for an automatic transmission for automobiles.

[0002]

2. Description of the Related Art In a vehicle equipped with an automatic transmission, when a traveling condition on a bad road is detected and the vehicle travels on a rough road, the hysteresis region of the shift map for controlling the shift is expanded to hunt the shift, that is, It is disclosed in Japanese Patent Application Laid-Open No. 4-60265 to prevent repeated shifts between matching speed stages. By the way, what is required of an automobile when driving on a rough road is good responsiveness that accurately responds to the driver's intention, in particular, stable acceleration / deceleration by accelerator work, that is, engine braking when the accelerator is loosened. It works well and you can accelerate quickly when you step on the accelerator, and it is not important that you can drive at high speeds.

[0003]

However, in the device of the above publication, only the hunting of the shift is prevented and the responsiveness is prevented from changing. It is not prohibited. Therefore, when it is attempted to operate in the speed range in which the vehicle can travel at the fourth speed stage (maximum speed stage) or the third speed stage,
An upshift to the speed stage (highest speed stage) is performed,
As a result, the vehicle speed increases and the effectiveness of the engine brake deteriorates, and it is necessary to repeatedly perform the operation that the driver steps on the brake to decelerate again. There is. In view of the above problems, the present invention is to provide a shift control device for an automatic transmission, which can reduce a brake operation when traveling on a rough road and can perform stable acceleration / deceleration by accelerator work.

[0004]

According to claim 1 of the present invention, as shown in FIG. 1 (a), a shift control of an automatic transmission for selecting a speed stage in accordance with a running state of a vehicle to shift gears. A device, a bad road running determination means for determining whether or not a bad road running state, and a maximum speed stage prohibiting means for prohibiting running at a maximum speed stage when it is determined to be a bad road running state There is provided a shift control device for an automatic transmission, characterized by comprising: According to claim 2, as shown in FIG.
2. The maximum speed stage prohibiting means downshifts from the maximum speed stage in response to a brake operation when it is determined that the vehicle is traveling on a rough road when traveling at the maximum speed stage. A shift control device for an automatic transmission is provided. According to claim 3, as shown in FIG.
When it is determined that the vehicle is running on a rough road, the vehicle is equipped with a low-speed shift means for downshifting to a speed stage where a lower engine brake is effective in response to a brake operation when traveling at a speed stage other than the maximum speed stage. A shift control device for an automatic transmission according to claim 1 or 2, is provided.

[0005]

According to the first aspect, when it is determined that the vehicle is traveling on a rough road, traveling at the highest speed stage is prohibited. In the second aspect, when it is determined that the vehicle is traveling on a rough road at the highest speed stage, when the brake pedal is depressed, the downshift is performed from the highest speed stage. In the third aspect, when it is determined that the vehicle is traveling on a rough road, when the brake pedal is stepped on, the vehicle is downshifted to a lower speed side where the engine braking is effective.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. FIG. 2 schematically shows the configuration of the first embodiment. In FIG. 2, 1 is an engine, 2 is an automatic transmission that achieves four forward gears and one reverse gear, and 3 is an automatic transmission. 2 is a vehicle speed sensor incorporated in the inside of the vehicle 2 to detect rotation of an output shaft (not shown) of the automatic transmission 3. Reference numeral 4 is a brake pedal, and 5 is a brake sensor attached to the brake pedal.

Reference numeral 6 denotes an electronic control unit (hereinafter referred to as ECU), which is connected to each other via a bidirectional bus 7 such as RAM 8, ROM 9, CPU 10, input port 11,
The output port 12 and the drive circuit 13 are included. In the first embodiment, the acceleration is obtained from the pulse signal of the vehicle speed sensor 3 input from the input port 11, and it is determined whether or not the vehicle is traveling on the rough road based on the change in the acceleration. In addition to playing a role, when the rough road traveling determination means determines from the output port 12 via the drive circuit 13 that the rough road traveling state is in effect, the maximum speed stage is prohibited and the shift output is performed. Also plays the role of. It should be noted that various signals such as the engine 1 are input to the input port 11.
A throttle opening, a signal indicating the shift position of the shift lever, and the like are input.

Next, the processing performed inside the ECU 6 will be described. First, FIGS. 3 and 4 show changes in acceleration when traveling on a rough road and traveling on a flat and good road, respectively. As shown in FIG. The magnitude of acceleration vibrates in the plus and minus directions during a relatively short time, while
As shown in FIG. 4, when traveling on a flat and good road, the above-mentioned change in acceleration does not appear.

FIG. 5 is a flow chart for judging the traveling state on a rough road by paying attention to the acceleration change that occurs during traveling on a rough road. The absolute value of the acceleration a exceeds a predetermined judgment value α. The lower limit value T1
And the upper limit value T2, the rough road traveling state is determined. Here, the lower limit value T1 excludes signals that are considered to be noise, and the upper limit value T1
2 distinguishes between a rough road traveling state and a state where the acceleration change continues for a relatively long time, such as when the drive wheels slip.

In the flowchart of FIG. 5, first,
In step 1, the acceleration a is taken in, and in step 2,
It is determined whether or not the absolute value | a | of the acceleration a captured in step 1 exceeds a predetermined determination value α. If the determination result in step 2 is YES, that is, if the acceleration a exceeds the determination value α, the process proceeds to step 3 and the duration T after the absolute value | a | of the acceleration a exceeds the determination value α is acquired. In steps 4 and 5, whether the duration T is larger than the lower limit value T1 and the upper limit value T
It is a step of determining whether or not it is 2 or less, and when both the determinations of steps 4 and 5 are satisfied, that is,
When T1 <T ≦ T2, it is determined that the vehicle is running on a rough road, and in step 6, a flag XAKURO indicating that the vehicle is running on a rough road is set (returning XAKURO = 1) and the routine returns.

On the other hand, if the result of the determination in step 2 is NO, it means that the vehicle is not traveling on a bad road, so the routine proceeds to step 7, where the timer is reset, and then the routine proceeds to step 8 to clear the flag XAKURO (XAKURO = (0) Indicates that the vehicle is not traveling on a rough road and returns.
Even when the determination result in steps 4 and 5 is NO, the magnitude of the acceleration a exceeds the determination value α, but the duration time T
Is out of the condition and is not in a bad road running state, the routine proceeds to step 8 and similarly, the flag XAKURO is cleared to show that it is not in a bad road running state (XAKURO = 0.
And).

Next, FIG. 6 shows, in response to a brake operation, when it is determined by the routine of the flowchart shown in FIG. 5 that the vehicle is traveling on a rough road, the maximum speed stage, in this case, the fourth speed stage to the third speed stage. 6 is a flowchart showing an operation for downshifting to a speed stage. First, in steps 101 to 103, it is determined whether or not the conditions for executing the control for prohibiting the highest speed stage are satisfied. That is, in step 101, the rough road running flag XAKURO
Is 1, a step 102 determines whether the vehicle speed V is a predetermined high speed traveling or not, and a step 103 determines whether the vehicle is traveling in the D range.

When all the determinations in steps 101 to 103 are established, the routine proceeds to step 104, where the flag XNH indicating the execution state of the control for prohibiting the maximum speed stage is 0, that is, the control for inhibiting the maximum speed stage is executed. Determine if you have not. Initially, step 104 is Y
Since it is determined to be ES, the routine proceeds to step 105, where it is judged whether or not the vehicle is traveling at the fourth speed stage. When it is determined in step 105 that the gear position is the fourth speed stage, the process proceeds to step 106 and NO.
If it is determined that the process is completed, the process proceeds to step 108.

YES in step 105, that is, the fourth
When it is determined that the vehicle is traveling at the speed stage and the routine proceeds to step 106, at step 106, the engine is overrevised when the downshift from the fourth speed stage to the third speed stage is performed based on, for example, the vehicle speed and the engine speed. If the engine does not overrev, it is determined in step 107 whether the brake operation is performed. If YES is determined in step 107, the process proceeds to step 110, a command for traveling in the third speed stage is output, and the flag XNH is set to 1 in step 140 to execute the control for prohibiting the maximum speed stage. And returns. On the other hand, NO in steps 106 and 107
If it is determined that the flag X
NH is cleared to 0 to indicate that the control for prohibiting the maximum speed stage is not executed, and the process returns.

As described above, when it is determined that the vehicle is traveling on a rough road, the vehicle is traveling at the fourth speed stage, and if the engine does not overrev even if the engine is downshifted, the brake operation is performed. In response to this brake operation, the engine is downshifted from the fourth speed stage, that is, the control for prohibiting the highest speed stage is executed, and conversely, even if the vehicle is traveling at the fourth speed stage, the engine is downshifted. If overrev is applied or if the brake operation is not performed, the control for prohibiting the maximum speed stage is not executed and the downshift from the fourth speed stage is not performed.

On the other hand, if NO at step 105, that is, if the vehicle is not traveling at the fourth speed, the routine proceeds to step 108, at which the upshift from the third speed to the maximum speed is judged. JE
S, that is, if upshifting is about to be performed, this is stopped in step 109, and step 110
To output a command to run at the third speed stage, and
Proceeding to 40, the flag XNH is set to 1 and the process returns. If NO in step 108, the process directly proceeds to step 140, sets the flag XNH to 1, and returns. In this way, when it is determined that the vehicle is traveling on a rough road, if the vehicle is not traveling at the fourth speed stage, the control for prohibiting the maximum speed stage is immediately executed.

If the flag XNH is set to 1 in step 140 and the control for prohibiting the maximum speed stage is being executed, the flow from the next time onward will be from step 101 to step 101.
As long as all the judgments in 103 are established, step 10
When NO is determined in step 4, the process proceeds to steps 108 and 109, the same operation as described above is performed, and the control for prohibiting the maximum speed stage is continued.

As described above, in the first embodiment, when the vehicle is traveling on a rough road at the maximum speed stage (fourth speed stage) in the D range, overrev is required even when downshifting to the third speed stage. For example, when the brake is depressed, the vehicle is downshifted to the third speed stage, and when traveling at the third speed stage, the upshift to the highest speed stage (fourth speed stage) is prohibited.

FIG. 7 is a flow chart of a second embodiment in which, when the engine brake is applied in all of the D range, the engine is operated so as to downshift to a speed stage where the engine brake is more effective in response to the brake operation. Is. This flowchart is different in steps 108 to 110 of the flowchart of the first embodiment shown in FIG. 6 but is otherwise the same. Therefore, FIG. 7 shows only the portions different from the first embodiment.

In the second embodiment, when the vehicle travels on a rough road at the maximum speed stage of the D range (fourth speed stage),
If you do not overrev even if you downshift to the speed stage,
When the brake is depressed, the same step 1 as in the first embodiment
From 01 to step 107, the process proceeds to step 128, which performs the same operation as step 110 in the first embodiment, and a travel command for the third speed stage is issued and downshifting to the third speed stage is performed. On the other hand, other than the highest speed, the third speed,
When traveling on a rough road at the second speed stage and the first speed stage,
In the embodiment, step 104 common to the first embodiment.
Alternatively, NO is determined in 105, and step 1
Proceed to 21.

First, consider the case where the vehicle is traveling at the third speed stage. In step 121, whether the current speed V is lower than the maximum possible speed V2 of the second speed stage, that is, downshift to the second speed stage. Then, it is determined whether or not overrev is performed, and if the determination result is YES, the process further proceeds to step 122, where the speed V is greater than the maximum possible speed V1 of the first speed stage and the maximum possible speed V2 of the second speed stage. It is determined whether or not it is smaller, that is, whether or not the second speed is not overrev, and the first speed is overrev.

If it is also determined YES at step 122, the routine proceeds to step 123, where it is determined whether or not the currently traveling speed stage is the third speed stage. Since it is considered, it is determined as YES in step 123, the process proceeds to step 124, and step 1
In 24, it is determined whether the brake is depressed,
If YES, it is determined that the driver wants to decelerate, the routine proceeds to step 129, where a command to travel at the second speed stage is issued, and a downshift from the third speed stage to the second speed stage is executed. .

On the other hand, if NO in step 121, it means that the vehicle is traveling at a speed that causes an overrev when downshifting to the second speed stage. Therefore, the process proceeds to step 128 to issue a command to drive in the third speed stage. Continue running at the 3rd speed stage. Also, if NO in step 124, overrev does not occur even if the vehicle travels at the second speed stage, but the driver does not want to decelerate.
Proceed to 28 to continue traveling at the third speed stage.

If the vehicle is traveling in the third speed stage at a speed that does not cause overrev when traveling in the first speed stage, NO is determined in step 122 and step 125 is performed.
However, if it is confirmed in step 125 that the vehicle is traveling in the third speed stage, the process proceeds to step 124, and the downshift from the third speed stage to the second speed stage is executed as described above. . This is in addition to the above, from the third speed stage to the first
This is for prohibiting excessive deceleration due to one-step downshift to the speed stage.

Next, when the vehicle travels at the second speed stage and the traveling speed V does not overrev at the second speed stage but does overrev at the first speed stage, step 121,
In step 122, it is determined to be YES, and in step 123.
Proceed to step 1, but step 1
In No. 23, NO is determined, and the routine proceeds to Step 129, where the second
The traveling in the second speed stage is continued by commanding traveling in the second speed stage.

On the other hand, if the vehicle is traveling at the second speed stage but the traveling speed V does not cause overrev even at the first speed stage, NO is determined in step 122 and the routine proceeds to step 125 where the vehicle is traveling in the third speed stage. Is determined. Since the vehicle is traveling at the second speed stage, NO is determined in step 125 and the process proceeds to step 126.
It is determined whether or not the vehicle is traveling at the speed stage. Since the vehicle is traveling at the second speed stage, YES is determined and the process proceeds to step 127 to determine whether or not the brake is depressed.

If the determination result of step 127 is YES, it is determined that the driver wants to decelerate and step 13
0, a command to travel at the first speed stage is issued, and a downshift from the second speed stage to the first speed stage is executed. On the contrary, if NO in step 127, the vehicle does not overrev even if the vehicle travels in the first speed stage, but the driver does not want to decelerate. Therefore, the process proceeds to step 129 and the vehicle travels in the second speed stage. continue.

When traveling at the first speed stage,
When it is determined YES in step 121, NO in step 122, NO in step 125, and NO in step 126, the process proceeds to step 130 and a command to travel at the first speed stage is issued to continue traveling at the first speed stage.

At steps 128, 129, and 130, after issuing commands for traveling at the third speed stage, the second speed stage, and the first speed stage, respectively, the routine proceeds to step 131, at which the number of speed stages currently in use is determined. After inputting and proceeding to step 140 in FIG. 5, the flag XNH is set to 1 to indicate that the control for prohibiting the maximum speed stage is being performed, and the process returns.

As described above, in the second embodiment, even when the vehicle travels on a rough road at the maximum speed stage (fourth speed stage), the third speed stage, and the second speed stage of the D range, even if a downshift is performed. If there is no overrev, when the brake is depressed, the gear is downshifted to the next lower speed stage.

In the above description of each embodiment, the acceleration is determined from the pulse signal of the vehicle speed sensor 3 as the bad road running determination means, and it is determined whether or not the road is running on the bad road based on the change in the acceleration. For example, it may be one that determines the bad road running state from the vibration of the suspension, or may be the bad road running determining means disclosed in Japanese Patent Application Laid-Open No. 4-60265.

[0032]

According to the first aspect of the present invention, on a rough road, the maximum speed stage is prohibited, and the vehicle travels at a speed stage where engine braking is more effective. Therefore, the accelerator pedal of the driver is higher than when the vehicle travels at the maximum speed stage. The responsiveness of the vehicle to the work is improved,
The driving feeling is improved, the number of times the brake is applied is reduced, and the stability of the vehicle is improved. According to the second aspect, when the brake is depressed, the downshift is performed from the maximum speed stage. Therefore, when the driver wants to decelerate, the vehicle automatically travels to a speed stage where engine braking is more effective. Although the shift is made, it is not performed when the driver does not want to decelerate because the brake is not depressed, so that a downshift contrary to the driver's intention is prevented and the driving feeling is further improved. According to the third aspect, the engine braking is effective in response to the braking operation, and the vehicle is automatically downshifted to a lower speed stage, so that the safety of the vehicle is further improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a concept of control of a shift control device for an automatic transmission according to each claim of the present invention, in which (a) is the first claim;
The concept of control of the shift control device of the automatic transmission by
(B) shows a concept of control of a shift control device for an automatic transmission according to claim 2, and (c) shows a concept of control of a shift control device for an automatic transmission according to claim 3.

FIG. 2 is a diagram showing a configuration of a shift control device for an automatic transmission according to the present invention.

FIG. 3 is a diagram showing changes in acceleration during traveling on a rough road.

FIG. 4 is a diagram showing a change in acceleration of the vehicle when traveling on a flat and good road.

FIG. 5 is a flowchart for determining a rough road traveling state.

FIG. 6 is a flowchart of a control for prohibiting the highest speed stage during traveling on a rough road according to the first embodiment of the present invention.

FIG. 7 is a flowchart of control for downshifting to a lower speed stage during traveling on a rough road according to the second embodiment of the present invention (only the portion different from FIG. 6).

[Explanation of symbols]

 1 ... Engine 2 ... Automatic transmission 3 ... Vehicle speed sensor 4 ... Brake pedal 5 ... Brake sensor 6 ... Electronic control unit

Claims (3)

[Claims] 1. A shift control device for an automatic transmission, which shifts gears by selecting a speed stage in accordance with a running condition of a vehicle, comprising: a bad road running judging means for judging whether or not a bad road running condition; A shift control device for an automatic transmission, comprising: a maximum speed stage inhibiting means for inhibiting traveling at a maximum speed stage when it is determined that the vehicle is in a traveling state. 2. The maximum speed stage prohibiting means downshifts from the maximum speed stage in response to a brake operation when it is determined that the vehicle is traveling on a rough road when traveling at the maximum speed stage. The shift control device for an automatic transmission according to claim 1. 3. When it is determined that the vehicle is traveling on a rough road, when the vehicle travels at a speed stage other than the maximum speed stage, in response to a brake operation, a downshift is made to a lower speed stage where engine braking is effective. The shift control device for an automatic transmission according to claim 1 or 2, further comprising a low speed shift means.