JPH0439128A - Constant speed travel control device for automobile - Google Patents

Abstract

PURPOSE:To optimally perform constant speed travel control at the time of travel along an ascent by resetting a travel mode to an overdrive constant speed travel mode, when throttle opening becomes less than a throttle opening threshold value, after releasing the overdrive constant travel mode with shift- down operation. CONSTITUTION:In such a case where an automobile runs along an ascent during constant speed travel, an overdrive travel mode is released when the speed of the automobile drops by the predetermined speed V1 from a target speed Vo and this state continues for the predetermined time t1. Furthermore, comparison is made between throttle opening thetaa and a throttle opening threshold value thetaTH in every predetermined time t2. When the throttle opening thetaa drops below the throttle opening threshold value thetaTH, the travel mode is reset to the overdrive travel mode. According to the aforesaid construction, the overdrive travel mode is immediately reset, when the throttle opening thetaa drops below the throttle opening threshold value thetaTH. Consequently, the resetting of the overdrive travel mode can be finely controlled, according to the slope of a road.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a constant speed driving control method for an automobile for maintaining the automobile at a desired constant speed, that is, a target vehicle speed, and causing the automobile to travel automatically.

(Prior Art) This type of constant speed driving control method is applied to automobiles equipped with automatic transmissions, and is used to maintain the vehicle at a constant target vehicle speed and drive automatically. This is designed to reduce the burden on drivers.

To explain this type of constant speed driving control in more detail, when a car is traveling at a constant speed in overdrive gear and is traveling uphill, the actual speed of the vehicle may exceed the allowable range from the target vehicle speed. When the speed decreases, the automatic transmission is automatically downshifted from overdrive, releasing automatic drive, and once the throttle valve is wide open, the vehicle will continue to shift until the actual vehicle speed reaches the target vehicle speed. It will be accelerated. After this, the automatic transmission is automatically returned to the automatic drive gear, and the throttle/slottle valve is also returned to the throttle/sottle opening that allows the actual vehicle speed to be maintained at the target vehicle speed. The vehicle will be returned to constant speed driving using overdrive. That is, when the target vehicle speed of the vehicle is set,
The opening of the throttle valve and the gear position of the automatic transmission in the automobile are controlled so that the actual vehicle speed matches the target vehicle speed.

(Problem to be Solved by the Invention) By the way, as mentioned above, when driving uphill at a constant speed with overdrive, the overdrive is temporarily canceled due to a decrease in the actual vehicle speed, and the actual vehicle speed does not reach the target vehicle speed. Once accelerated, it will return to overdrive,
This overdrive release and restoration are both performed in accordance with the vehicle speed deviation between the actual vehicle speed and the target vehicle speed.

However, when overdrive is controlled by the vehicle speed in this way, overdrive is returned after the actual vehicle speed has increased and the target vehicle speed has been reached, so there is a delay in returning to overdrive. This results in an inability to optimally control the actual vehicle speed relative to the target vehicle speed.

This invention was made based on the above-mentioned circumstances, and
The purpose of this is that even when the car is driving uphill while driving at a constant speed in overdrive,
An object of the present invention is to provide a constant speed driving control method for an automobile, which can optimize constant speed driving control in overdrive.

(Means for Solving the Problems) In the constant speed driving control method for a vehicle of the present invention, when the vehicle speed decreases by a predetermined speed from the target vehicle speed while the vehicle is traveling at a constant speed in overdrive, a downshift operation is performed. After canceling overdrive constant speed driving, the throttle opening of the throttle valve obtained from the vehicle's throttle opening sensor is less than the throttle opening threshold required to maintain the target vehicle speed during overdrive constant speed driving. When it becomes smaller, the system returns to overdrive constant speed driving.

(Function) According to the constant speed driving control method of the present invention, in order to return to overdrive after the overdrive is released, the throttle valve is determined not from the vehicle speed but from the throttle opening sensor. The throttle opening will be taken into consideration. That is, when the throttle opening becomes smaller than the throttle opening threshold required to maintain the target vehicle speed during overdrive constant speed driving, overdrive constant speed driving is returned.

(Embodiment) Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. 1 to 6.

Referring to FIG. 1, a constant speed traveling device for carrying out a constant speed traveling control method for an automobile is schematically shown.

The constant speed traveling device is applied to an automobile equipped with an engine 2 with an automatic transmission 1, and in this case, the automatic transmission 1 has an overdrive gear.

The constant speed traveling device includes a controller 4 for controlling the speed change operation of the automatic transmission l and the throttle opening of the throttle valve 3. Therefore, the controller 4 controls the speed change operation of the automatic transmission l. hydraulic gear shift operation mechanism 5;
Further, control signals are outputted to the throttle drive mechanism 6, which drives the throttle valve 3 and varies its throttle opening. Here, the throttle drive mechanism 6 may be of a type that drives the throttle valve 3 using a negative pressure drive type actuator, or may be of a type in which the valve shaft of the throttle valve 3 is driven by an electric motor. It may be of a type driven by a drive mechanism.

Control signals from the controller 4 are output based on signals from various sensors and switches, and the sensors include:
First, there are a vehicle speed sensor 7, a throttle opening sensor 8, etc., and switches include a main switch 9, a set switch 1O, a stop lamp switch 11, a resume switch 12, an inhibitor switch 13, an accelerator switch 14, etc.

First, the basic operation of the constant speed traveling device will be briefly explained. While the car was running in an overdrive gear, the driver turned on the main switch 9 to drive at a constant speed, and confirmed with the speedometer (not shown) that the desired speed had been reached. When the set switch 10 is turned on, the vehicle speed at this point in time is set to the target vehicle speed, and at the same time constant speed driving control is started. After this, the controller 4 calculates the deviation between the target vehicle speed and the actual vehicle speed obtained from the sensor signal from the vehicle speed sensor 7 based on a predetermined control law, and adjusts the throttle according to this deviation. The throttle opening of the throttle valve 3 is controlled via the drive mechanism 6, the output of the engine 2 is adjusted, and the actual vehicle speed is maintained at the target vehicle speed. Here, the throttle opening is detected by the throttle opening sensor 8, and in the controller 4, the detected throttle opening is adjusted so that the change in the output of the engine 2 is linear with respect to the throttle opening. Appropriate corrections have been made to the opening.

When the driver depresses the brake pedal (not shown) during the above-described constant speed driving, the stop lamp switch 11 as a cancel switch is turned on in conjunction with the brake pedal, thereby canceling the constant speed driving control. Ru. Note that when the automatic transmission 1 is switched to the neutral position and the driving force from the engine 2 is not transmitted to the wheels,
An inhibitor switch 1 that is linked to a gear shift lever (not shown) of the automatic transmission 1 and functions as a cancel switch.
3 is turned on, the constant speed running control is canceled, thereby preventing the engine 2 from revving up.

Next, a constant speed running control method executed by the controller 4 according to the overdrive control routine shown in FIGS. 2 to 4 will be described. Here, the overdrive control routine includes a predetermined control cycle (for example, 30m5
ec) is executed repeatedly.

First, when the constant speed running control is started while the automobile is running in the overdrive gear, first, step Sl in FIG.
Initial settings will now be performed. Here, the initial settings are
The target vehicle speed Vo of the automobile is set, and each flag used in the overdrive control routine is reset to zero.

In the next step S2, the controller 4 reads the vehicle speed Va and the throttle opening θa based on the sensor signals from the vehicle speed sensor 7 and the throttle opening sensor 8, and in step S3, l is set in the flag FLGI. It is determined whether or not it is set. Here, immediately after the overdrive control routine is started, the determination in step S3 is negative (No), so the determination in step S3 is negative.
4, and in this step, the vehicle speed Va becomes the target vehicle speed vO.
It is determined whether the vehicle speed has decreased by a predetermined vehicle speed Vl (for example, 3 km/h) or more, that is, whether the following equation is satisfied.

Va≦Vo −Vl = (1) During constant speed driving control, when the vehicle is traveling on a flat road, the vehicle speed Va is maintained at the target vehicle speed Vo by only controlling the throttle opening θa of the throttle valve 3. Since it is possible, the determination of equation (11) in step S4 is negative, and the next step S5 is executed, and then the process returns to step S2. In this step S5, the timer TI is reset.

However, when the vehicle is traveling uphill during constant speed driving control, the determination of the above equation (11) is correct (
Yes), steps S4 to S6 are performed. In this step S6, the timer Tl
time measurement is started, and the next step S7
, the value of timer TI is tl (for example, 1.2
sec) or more is determined. Since the determination here is still just after the start of time measurement by the timer TI, the determination is negative and the process returns to step S2. Therefore, as long as the determination in step S4 remains positive, step S6 is repeatedly executed and the value of timer TI continues to be added.

Then, when the determination in step S7 becomes positive, steps S7 to S8 are executed for the first time, in this step S8, the value of the timer TI is reset to 0, and in the next step S9, the flag FLGI to 1
After is set, the process returns to step S2. Therefore, once step S9 is executed in this way, in the next control cycle, since the determination at step S3 becomes positive, the steps after step S4 are no longer executed.

On the other hand, if the determination in step S4 is negative while the timer T1 continues to measure time, the timer TI is reset in step S5. In the control cycle, time measurement by the timer Tl is started from the beginning after the determination in step S4 becomes positive again.

Therefore, step S9 is performed only when the vehicle speed Va decreases to a predetermined speed or more below the target vehicle speed Vo, and this state continues for a predetermined period of time.

Once step S9 is executed, in the next control cycle, steps S3 to S1O in FIG. 3 are executed, and in this step, overdrive (OD) is canceled. That is, when step SIO is executed, a control signal is output from the controller 4 to the hydraulic shift operation mechanism 5, and as a result, as shown in FIG. 5, the gear stage of the automatic transmission l changes from OD to It will be downshifted to 3rd gear. Further, as is clear from FIG. 5, this downshift may be performed when the vehicle speed Va decreases to a predetermined vehicle speed V1 or more below the target vehicle speed Vo, and this state continues for a predetermined time 11. I understand.

In the next step Sll, it is determined whether the flag FLG2 is set to 1, but even in this case,
Since flag FLG2 remains reset to 0,
The determination is negative, and step S12 is executed.

In this step, the value of the counter N is incremented by 1, and in the next step S13, the value of the counter N is increased to Nlmax (for example, N1max=21).
It is determined whether or not the above value has been reached. Here, step 3
Immediately after overdrive is released at step 10, the value of counter N remains set to the initial value 0, so
The determination in step S13 is negative, and the process proceeds to step S14 in FIG. 4, where the flag FLG2 is set to 1.

In the next step S15, time measurement by the timer T2 is started, and in the next step S16, the timer T2 starts measuring time.
It is determined whether the value of 2 has reached a predetermined time [2 (for example, 8 seconds). At this point, the determination is still negative, so the process returns to step S2 in FIG. 2 and the next control cycle is executed. Here, in the next and subsequent control cycles, step S3. Since all the determinations in Sll are positive, steps S2, S3. After SIO, Sll, and S14, step S15
．． S16 will be executed repeatedly. In other words,
In this case, in step SIO, only time measurement by timer T2 is performed while overdrive is maintained released.

In the process of time measurement in this way,
Since step S2 is repeatedly performed, the vehicle speed V
a and throttle opening θa are always read by the controller 4 and updated to the latest values. Also, the fifth
As shown in the figure, the throttle opening θa changes the vehicle speed Va to the target vehicle speed V based on the vehicle speed Va and the gear position at that time.

Of course, it is controlled by the controller 4 in order to match the .

Then, when the timer T2 is measuring time as described above, if the determination in step S16 is positive, that is, if a predetermined time t2 has elapsed since the overdrive was released in step SIO, then the next Step S1
7 will be implemented. In this step, the throttle opening θ
It is determined whether a is smaller than a throttle opening threshold value θTH. Here, the throttle opening threshold θTH is the sixth
It is obtained from the map shown in the figure, and this map is
This represents the throttle opening required for the target vehicle speed when a vehicle attempts to run at a constant speed on a slope of, for example, 2.5% in an overdrive gear. The map shown in FIG. 6 is stored in the controller 4 in advance.

In step S17, the throttle opening threshold θT)l obtained from the target vehicle speed Vo based on the map in FIG. 6 is compared with the current throttle opening θa, and the throttle opening θa is larger than the throttle opening threshold θTH. If it is smaller, that is, if the determination is positive, it is determined that the output of the engine 2 is sufficient to maintain the actual vehicle speed Va at the target vehicle speed Vo, and the process proceeds to step S18 in FIG.
In this step, the gear position of the automatic transmission 1 is shifted up from 3rd speed to the overdrive gear position, and the constant speed driving by overdrive is returned to. That is, after the predetermined time t2 has elapsed since the overdrive was released, 1 by the timer T2 has elapsed since the overdrive was released.
If the determination in step S17 becomes positive after the completion of the second time measurement, the overdrive mode is returned to the overdrive state at this point.

After that, in step S19, the value of the counter N is reset to 0, and each flag FLGI.

After each FLG2 is reset to 0, the process returns to step S2 in FIG. 2 to execute the next control cycle. Therefore, in this case, since the determination in step S3 is negative, the above-described overdrive control routine is executed from the beginning, that is, the determination in step S4 is repeated.

If the determination in step S17 described above is negative, step 820. By sequentially executing S21, the value of timer T2 is reset to 0, and flag FLG2 is reset to 0.
is reset to 0 and the process returns to step S2.

In this case, when the next control cycle is executed, it passes through step SIO and reaches step Sll, but in this case, the determination in this step is negative, so the next step S
12 is executed, thereby the value of the counter N is further incremented by l, and step S13 is executed. Even in this case, since the value of Nlmax is set to 21 as described above, the determination is negative, and the fourth
The steps after step S14 in the figure are repeated. Therefore, when the time measurement by the timer T2 is repeatedly performed and the predetermined time t2 has elapsed,
The determination in step S17 will be performed. Therefore, as mentioned above, if the determination here is positive, the overdrive is restored, whereas if the determination is negative, the value of the counter N is further incremented by l, and then Time measurement by timer T2 is repeated,
The determination in step S17 will be performed again.

That is, as is already clear from the above description, step S1
The determination in step 7 is repeated every predetermined time period t2 from when the overdrive is released until the determination becomes positive and the overdrive is restored in step S18. However, the value of counter N is 21
, and if the determination in step 817 is negative even at the 20th time, step 513
At this time, the determination becomes correct for the first time, and step S18 is executed, whereby the overdrive is forcibly canceled and the overdrive is restored.

To summarize the overdrive control routine of the first embodiment described above, when the automobile is traveling uphill while traveling at a constant speed, the vehicle speed Va is the target vehicle speed V.

, the vehicle speed decreases by a predetermined amount Vl, and this state lasts for a predetermined time t.
l, overdrive is released. Then, after this, the throttle opening θa and the throttle opening threshold θ
TH is determined at predetermined time intervals t2, and when the throttle opening θa becomes smaller than the throttle opening threshold θTH, the overdrive is restored or the determination is made. After repeating 20 times, it will be forcibly returned to overdrive.

Therefore, according to the constant speed driving control method of the first embodiment, when returning to overdrive after overdrive has been released, the throttle opening θa, which represents the degree of gradient of the road on which the vehicle is traveling, is adjusted. Considering this throttle opening θa
Since the overdrive is immediately returned to when the throttle opening degree becomes smaller than the throttle opening threshold θT)I, it is possible to finely control the return of the overdrive depending on the gradient of the road on which the vehicle is traveling.

Furthermore, even if a predetermined period of time or more elapses after the overdrive is released, that is, even if the time measurement by timer T2 is repeated 20 times, the throttle opening θa does not become smaller than the throttle opening threshold θTH. Since the overdrive is restored, the overdrive release state will not continue for an undesirably long time.

That is, even when driving on a gentle uphill slope during constant speed driving control, it is determined that this uphill slope will not continue for more than a predetermined driving time, and the overdrive is returned to. become.

This invention is not limited to the first embodiment described above and can be modified in various ways. explain.

In this second embodiment, the predetermined speed v1 is set to 7 km/h and the predetermined time t1 is set to 0 in the flowchart of FIG. 2 described above.

Therefore, in the case of this second embodiment, each step from step S5 to step S8 is substantially not performed (because the step S9 is performed immediately after the vehicle speed Va decreases from the target vehicle speed VO to below the predetermined speed Vl). will be executed, and in the next control cycle, the flowcharts of FIGS. 7 to 9 will be executed from step S3.

That is, from step S3 in FIG. 2 to step S2 in FIG.
2 is executed, and in this step, the overdrive is canceled as in step SIO in FIG. 3 described above.

That is, in this second embodiment, the overdrive is canceled as soon as the determination in step S4 becomes positive. This point will become clear with reference to Fig. 1θ.

In the next step S23, it is determined whether the vehicle speed Va has returned to within a predetermined vehicle speed V1 with respect to the target vehicle speed Vo, that is, whether the following equation is satisfied.

Vo −Vl ≦Va ≦Vo = (21
If the above equation (2) is not satisfied, step S23
If the determination is negative, step 324 is executed, where the timer T3 is reset, and then the process returns to step S2. Therefore, unless the determination in step S23 becomes positive, that is, unless the vehicle speed Va returns from the target vehicle speed Vo to within the predetermined speed V1, the steps after step S25 will not be executed.

However, if the vehicle speed Va increases and the determination in step S23 becomes positive, steps from step 25 onward are executed from this point on, and first, in step S25,
It is determined whether flag FLG3 is set to 1 or not. Since the determination here is still negative, the next steps from step 326 to step S29 are executed. Here, steps S26 to S29 are steps S6 to S9 in the flowchart of FIG.
The steps are similar to those in , so here,
To avoid repeating the explanation, only the points implemented in steps 326 to S29 will be briefly explained. That is, in these steps, after the determination in step S23 becomes positive, the timer T3 starts measuring time, and the value of the timer T3 reaches the predetermined time t3.
(For example, 8 seconds), FLG3 is set to 1 in step S29. Therefore, step S
After the predetermined time t3 has passed after 23 becomes positive, the determination in step S25 becomes positive, so in the subsequent control cycle, steps S26 to S29 are not executed, and steps S25 to 8 Step S in the diagram
Steps 30 and subsequent steps will be performed.

In step S30, it is determined whether or not the flag FLG4 is set to 1. At this point, the determination is negative, and the next step S31 is executed. Here, similarly to step S17 in FIG. 4 described above, it is determined whether the throttle opening degree θa is smaller than the throttle opening degree threshold value θT)l.

That is, the determination in step S23 becomes positive and the predetermined time t3
At the point in time when , the determination in step S31 will be performed.

If the determination in step S31 is positive, step S3
After returning to overdrive in step S33
At step S2, the counter N and each flag are reset to 0, and the process returns to step S2.

However, if the determination in step S31 is negative,
After the value of the counter N is incremented by 1 in step S34, the value of the counter N is incremented by 1 in the next step S35.
It is determined whether the value of has reached N2max (for example, N2max=31) or more. Here, first step S
If the determination in step S31 is performed and the process goes through step S34 to step S35, this step S
Since the determination at step S35 is negative, the steps after step S36 shown in FIG. 9 are executed next. That is, in step S36, after the flag FLG4 is set to 1, time measurement by timer T4 is started in step 337, and in the next step 338, the value of timer T4 is set to 1 for a predetermined time t4 (for example, 4 seconds). ) is reached.

Unless the determination in step 838 is positive, that is, the time measurement by timer T4 in step 337 is not performed until the predetermined time t4 has elapsed since the determination in step S31, which was first performed, was negative. That will happen.

That is, step S36 is once implemented and the flag PLG
If 4 is set to 1, the determination in step S30 will be positive, so in this case, steps after step S31 will not be executed.

However, if the determination in step 838 is positive, the value of timer T4 is reset to 0 in the next step S39, and the value of the timer T4 is reset to 0 in step S40.
4 is reset to 0. Therefore, in the next control cycle after the predetermined time t4 has elapsed, step S
If the determination in step S30 is negative, the determination in step S31 will be performed again. If the determination here is positive, steps 332 and 333 described above are executed to return to overdrive. However, if the determination is still negative, step S34 is performed. ,
After the value of counter N is further incremented by 1,
The determination in step S35 will be performed. Here again, the value of N2IIlax is set to a large value as described above, so the determination in step S35 is negative, and time measurement by timer T4 is repeated as described above, and after this, again. , when the predetermined time t4 has elapsed, the determination in step S31 is performed.

Therefore, in the case of this second embodiment, after overdrive is released, vehicle speed Va is equal to target vehicle speed V.

When the speed returns to within the predetermined speed v1, first, after the elapse of a predetermined time t3, a determination is made in step 33, and if the determination in step S31 is negative, the predetermined time The determination in step S31 is repeated every t4. Also, step S3
When the determination in step 1 is repeated, when the value of the counter N reaches 31, the determination result in step S35 becomes positive, so at this point, step S32 is executed, as shown in FIG. 1O. As such, it will return to overdrive.

In the second embodiment described above, as is clear from the first (l), when determining the magnitude relationship between the throttle opening θa and the throttle opening threshold θTH, it is determined whether the vehicle speed Va has returned to a predetermined value. However, this determination may also be added to the method of the first embodiment.

That is, in the first embodiment, when the vehicle speed Va decreases below the target vehicle speed Vo to a predetermined speed V 1 (:3 km/h) and this state continues for a predetermined time tl, the overdrive is released. However, the subsequent determination of the magnitude relationship between the throttle opening θa and the throttle opening threshold θTH may be started from the time when the vehicle speed Va satisfies the following equation.

Vo −V2 ≦Va ≦Vo −(31
Here, V2 satisfies Vl > V2, and for example, if Vl is 3 km/h, V2 is set to 2 km/h.

In this case, as shown in addition to FIG.
In the embodiment, the determination in step S17 is performed every predetermined time t2 from the time when the vehicle speed Va satisfies the above-mentioned equation (3).

In the first and second embodiments described above, the throttle opening degree θa
The determination of the magnitude relationship between the threshold value θTH and the throttle opening threshold value θTH is carried out at predetermined time intervals, which are travel intervals. Well, in this case the third
Examples are illustrated in the flowcharts of FIGS. 11 and 12.

Here, even in the case of the third embodiment, the flowchart in FIG. 2 is common, and in addition to this FIG.
The flowchart in Figure 2 will be implemented.

Therefore, when the vehicle speed Va becomes lower than the predetermined speed V1 from the target vehicle speed Vo and this state continues for the predetermined time tl, the eleventh
Step S41 in the figure is executed and overdrive is released. Then, in the next step 42, the flag FL
It is determined whether G5 is set to 1, but since the determination at this point is negative, the next step S43 is executed. In this step, a predetermined value M50 (for example, 50 m) is added to the cumulative distance counter M, and in step S44, it is determined whether the value of the cumulative distance counter M has reached a predetermined distance Mmax (for example, 3000 m). be done. Here, since the determination in step S44 is still negative, step S45 in FIG. 12 is executed next, and after the flag PLG5 is set to 1 in this step, step S46 is executed. This step S
At 46, calculation of the mileage MO of the automobile is started by integrating the sensor signal from the vehicle speed sensor 7. After this, in the next step S47, the mileage MO
However, since the determination at this point is negative, in this case, the process returns to step S2 and the next control cycle is executed. Become. That is, in this case, step S46 will be executed until the determination in step S47 becomes positive. Thereafter, when the determination in step S47 is positive, it is determined in the next step 34B whether or not the throttle opening θa is smaller than the throttle opening threshold θTH. If the determination here is positive, step S49 in FIG.
By performing this, the overdrive is restored, and in the next step S50, the cumulative distance counter M and each flag are reset to 0, and the process returns to step S2.

However, if the determination in step 348 is negative, the value of the mileage MO is reset to 0 in step S51, and the flag FL is reset in step S52.
After G5 is reset to O, the process returns to step S2 to execute the next control cycle. In this case, by carrying out step S52, in the next control cycle, the determination in step S42 becomes negative, and the
Step S43 is executed, the value of the cumulative distance counter M is further incremented by M2O, and then the determination in step S44 is executed. Also, at this point,
Since the determination remains negative, the steps after step S45 are repeated to calculate the mileage MO, and when this mileage MO reaches the predetermined value M50, the determination in step 848 is made. will be repeated. Therefore, in the case of the third embodiment, each time the vehicle travels a predetermined distance M50 after the overdrive is released, it is determined whether the throttle opening θa is smaller than the throttle opening threshold θTH. The determination in step S48 is carried out, and when the determination is positive, the process proceeds to step S49 to return to overdrive. On the other hand, even if the determination in step 848 is not positive, if the value of the cumulative distance counter M has reached M max or more, the determination in step S44 is positive and the overdrive is returned. Here, the reason for returning to overdrive when the determination in step S44 becomes positive is as in the case of the first and second embodiments.
This is because there are no uphill slopes higher than 3000m.

The outline of the operation in the third embodiment described above is shown in a block diagram as shown in FIG. 13.

To briefly explain the functions of the resume switch 12 and the accelerator switch 14 shown in FIG. 1, as shown in FIG. 14, when the resume switch 12 is turned on, overdrive is released. Then, the vehicle speed Va is set to a predetermined vehicle speed V3 (
For example, after returning to within 2 km/h),
When 5 (for example, 65 ec) has elapsed, the overdrive is restored.

In addition, during overdrive constant speed driving control, when the accelerator pedal (not shown) is depressed and the accelerator switch 4 is turned on, if the resume switch 12 is turned on, as shown in FIG. After that, after a predetermined time t6 (for example, 0.6 sec) has elapsed, the overdrive is released, and after the resume switch 12 is turned off, a predetermined time t6 has elapsed.
After a period of time (for example, 1.8 sec) has elapsed, the overdrive mode is restored.

In each of the embodiments described above, the specific values of each predetermined time and the counter are merely examples, and these values may be changed as appropriate.

(Effects of the Invention) As explained above, according to the constant speed driving control method of the present invention, when the vehicle speed of the automobile decreases by 4 degrees or more from the target vehicle speed, the downshift operation of the automatic transmission is performed. After that, the throttle opening obtained from the vehicle's throttle opening sensor is lower than the throttle opening threshold required to maintain the target vehicle speed when driving at a constant speed with overdrive. Since it is designed to return to overdrive when the vehicle becomes smaller, even when driving at a constant speed, even when driving uphill, overdrive is adjusted according to the slope of the road surface. It is possible to finely control the return of the vehicle, resulting in effects such as being able to optimally implement overdrive constant speed driving control.

[Brief explanation of drawings]

1 to 6 show a first embodiment of the present invention, FIG. 1 is a schematic configuration diagram of a constant speed traveling device, and FIGS. 2 to 4 are flow charts showing an overdrive control routine. FIG. 5 is a graph showing changes in gear position, throttle opening, and vehicle speed over time when the overdrive control routine is executed; FIG. 6 is a graph showing throttle opening threshold values relative to target vehicle speed; FIG. Embodiment 2 of the present invention is shown in FIGS. 7 to 10, and FIGS.
Figure O is a graph showing changes in gear position, throttle opening, and vehicle speed over time, similar to Figure 5, and Figures 11 to 1.
3 shows a third embodiment of the present invention, FIGS. 11 and 12 are flowcharts of part of the overdrive control routine, FIG. 13 is a block diagram corresponding to the third embodiment, and FIG. The figure and FIG. 15 are graphs for explaining the functions of the resume switch and the accelerator switch. 1... automatic transmission, 3... throttle valve, 4...
Controller, 5... Hydraulic speed change operation mechanism, 6... Throttle drive mechanism, 7... Vehicle speed sensor, 8... Throttle opening sensor. Applicant Mitsubishi Motors Corporation Agent Patent Attorney Kan Nagato Figure 2 Figure 5 Figure 8 Figure 7 Figure 10 Figure 13

Claims (5)

[Claims] (1) When a vehicle equipped with an automatic transmission is traveling at a constant speed in an overdrive gear, if the vehicle speed decreases by a predetermined speed from the target vehicle speed, perform a downshift operation.
After canceling overdrive constant speed driving, the throttle opening of the throttle valve obtained from the vehicle's throttle opening sensor is less than the throttle opening threshold required to maintain the target vehicle speed during overdrive constant speed driving. A constant speed driving control method for an automobile, characterized in that when the vehicle becomes smaller, the vehicle is returned to overdrive constant speed driving. (2) The constant speed of the vehicle according to claim 1, wherein the overdrive constant speed driving is canceled when the vehicle speed decreases by a predetermined speed from the target vehicle speed and this state is maintained for a predetermined time. Travel control method. (3) The comparison between the throttle opening after the overdrive constant speed driving is canceled and the throttle opening threshold is performed from when the vehicle speed returns to within a predetermined speed difference with respect to the target vehicle speed. The constant speed driving control method for an automobile according to claim 1. (4) Comparison of the throttle opening after overdrive constant speed driving is canceled and the throttle opening threshold is carried out at every predetermined driving interval of the vehicle, and when the number of comparisons reaches the predetermined number, the comparison 4. The constant speed driving control method for an automobile according to claim 3, wherein the constant speed driving of an automobile is returned to the overdrive constant speed driving regardless of the result of the above. (5) The driving interval is defined by driving time, and the time interval at which the comparison is first performed is set to be longer than the time interval at which the comparison is repeatedly performed thereafter. The constant speed driving control method for an automobile according to claim 4.