JPH082739B2 - Control method of vehicle at constant speed - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a constant speed traveling control method for automatically traveling a vehicle at a desired constant speed, and in particular, a throttle position sensor partially fails. Even in the case, the present invention relates to a constant speed traveling control method capable of continuing the constant speed traveling function.

(Prior Art) A constant-speed traveling device is known that automatically travels a vehicle at a set speed (target vehicle speed) in order to reduce the burden on the driving operation when the vehicle travels at a constant speed.

This constant speed traveling device is provided with a throttle valve opening sensor (hereinafter referred to as "throttle sensor") that outputs a voltage signal according to the valve opening of a throttle valve arranged in the intake passage of an internal combustion engine, A throttle valve drive motor that opens and closes the valve is provided, and the driver operates the main switch for selecting the auto cruise mode to turn it on in order to perform constant-speed traveling (auto cruise) operation. When the target vehicle speed (auto cruise speed) is set by manually operating (turning on) the set switch by visually confirming that the target vehicle speed has been reached, the controller detects the target vehicle speed and the vehicle speed signal from the vehicle speed sensor based on a predetermined control law. The target voltage value corresponding to the target throttle valve opening is set according to the deviation from the (actual vehicle speed), and the set target voltage value and throttle Only driving amount corresponding to the difference between the voltage signal values of the capacitors to operate the throttle valve drive motor, i.e.,
The throttle valve driving motor opens and closes the throttle valve so that the voltage signal value of the throttle sensor matches the set target voltage value, thereby maintaining the target vehicle speed.

(Problems to be Solved by the Invention) In the conventional constant-speed traveling device, the throttle sensor 14 partially fails due to disconnection or short circuit due to vibration or aging,
The throttle valve opening may not be partially detected. FIGS. 8 and 9 show the output of the throttle sensor when the throttle sensor 14 partially fails, and FIG. 8 shows the output of the throttle sensor between θ ₁ and θ ₂ during the partial failure. The voltage drops to 0V, indicating that the throttle valve opening is normally detected in other sections. On the other hand, FIG. 9 shows that between the throttle positions θ ₁ ′ and θ ₂ ′, a partial failure occurs and the output voltage during this period is shorted to a high voltage (here, 5.0 V), and in other sections the throttle valve This indicates that the opening is normally detected.

When such a failure of the throttle sensor 14 occurs, even if it is a partial failure, the operation of the conventional constant-speed traveling device becomes defective, the entire system becomes inoperable, and the vehicle speed cannot be controlled. It was

The present invention can detect a partial failure of the throttle sensor and continue the vehicle speed control in a stable manner. Moreover, an abnormal output of the throttle sensor and a sudden accelerator pedal operation by the driver can be performed. It is an object of the present invention to provide a constant-speed traveling control method for a vehicle, which does not confuse the output suddenly changed.

(Means for Solving the Problems) According to the present invention in order to achieve the above-mentioned object, a throttle valve opening sensor for outputting a voltage signal according to a valve opening of a throttle valve of an internal combustion engine is provided, and an actual vehicle is provided. A target voltage value corresponding to the target throttle valve opening is set according to the deviation between the vehicle speed and the target vehicle speed, and the throttle valve is adjusted so that the voltage signal value detected by the throttle valve opening sensor matches the target voltage value. In the vehicle constant speed traveling control method for controlling the vehicle speed by driving the vehicle speed in the vicinity of the target vehicle speed, the relationship between the vehicle speed and the voltage signal value of the throttle valve opening sensor is obtained in advance,
The voltage signal output from the throttle valve opening sensor is sampled at a predetermined cycle, and it is determined whether or not the throttle valve opening sensor outputs an abnormal voltage signal based on the deviation between the previous sampling voltage value and the current sampling voltage value. Then, when the throttle valve opening sensor outputs an abnormal voltage signal, the throttle valve is opened or closed at a constant speed, and the vehicle speed and the voltage signal value of the throttle valve opening sensor obtained in advance are From the above relationship, the pseudo vehicle speed corresponding to the target voltage value is obtained, the actual vehicle speed is detected, and the output voltage of the throttle valve opening sensor returns to a normal value until a predetermined time elapses from the time when the abnormality is detected. Otherwise, it is determined that the throttle valve opening sensor has failed and the vehicle speed control is impossible, while the detected vehicle speed is the suspicious value by the time the predetermined time elapses. When greater than a predetermined speed than the vehicle speed, cruise control method for a vehicle, wherein a voltage signal of the throttle valve opening sensor continues to decision to vehicle speed control to be normal is provided.

(Function) Deviation between the previous sampling voltage value and the current sampling voltage value of the throttle valve opening sensor (expressed as an absolute value)
From this, it is determined whether or not the throttle valve opening sensor outputs an abnormal voltage signal due to a short circuit or disconnection. By this determination, it can be determined that the output voltage signal value of the throttle valve opening sensor is in an abnormal state, but it cannot be determined only by this whether or not the throttle valve opening sensor is partially defective. Therefore, the throttle valve is opened or closed at a constant speed. If the throttle valve opening sensor is partially defective, it should be restored to the normal sampling voltage value by passing through the defective section. Therefore, when the sampling voltage value does not return to the normal value even after the lapse of a predetermined time from the time when the abnormal voltage signal is discriminated from the deviation, it is determined that the throttle valve opening sensor fails and the vehicle speed control is impossible. However, even if the driver suddenly depresses the accelerator pedal, it is assumed that the deviation between the previous sampling voltage value and the current sampling voltage value of the throttle valve opening sensor may become an abnormally large value. In order to distinguish between accelerator pedal operation and sensor failure, the detected vehicle speed is compared with the pseudo vehicle speed, and when the actual vehicle speed is higher than the pseudo vehicle speed by a predetermined speed or more, it is determined that the voltage signal of the throttle valve opening sensor is normal. The vehicle speed control is continued after the determination.

Embodiment An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a constant speed traveling device in which the method of the present invention is carried out. This constant-speed traveling device is provided in a vehicle equipped with a gasoline engine, and the intake passage of the internal combustion engine 10
A throttle valve 6 is provided at 10a, and the throttle valve 6 is opened and closed by a drive motor 5 such as a pulse motor. A throttle valve opening sensor (throttle sensor) 14 is attached to the throttle valve 6 and supplies a voltage signal corresponding to the valve opening to the controller 3.

On the input side of the controller 3, in addition to the throttle sensor 14 described above, a main switch 1 for selecting an auto cruise mode, a set switch 2 for setting a target vehicle speed, a vehicle speed sensor 4 for detecting a vehicle speed, and a brake petal petal (not shown) are provided. A stop lamp switch 7 which is interlocked and also has a function as a cancel switch, a resume switch 8 for restarting constant speed traveling control, an automatic transmission (T / M) 11
Inhibit switch (not shown) that interlocks with the gear shift lever (not shown) and acts as a cancel switch
Are connected to supply signals from each sensor to the controller 3. The voltage signal value output by the throttle sensor 14 is sampled at a predetermined cycle (for example, every 300 msec) and read by the controller 3. On the other hand, the output side of the controller 3 is connected to an alarm device 9 for displaying a failure of the drive motor 5 and the throttle sensor 14 or an inability to control the vehicle at a constant speed.

After the driver turns on the main switch 1 to perform auto cruise operation, a speedometer (not shown)
When the target speed (auto cruise speed) U _ST is set by manually operating (turning on) the set switch 2 by visually confirming that the desired speed has been reached, the controller 3 sets The target voltage value V _ST corresponding to the target throttle valve opening is set according to the deviation between the target vehicle speed U _ST and the vehicle speed signal (actual vehicle speed) U from the vehicle speed sensor 4, and the set target voltage value V _ST and throttle are set. The operation amount of the drive motor 5 is calculated from the difference from the voltage signal value V _TPS output by the sensor 14, and the drive signal corresponding to the operation amount is supplied to the drive motor 5 to set the target voltage signal value V _TPS of the throttle sensor 14. Voltage value V
_The vehicle speed is controlled to match _ST, and thus the vehicle speed is maintained near the target vehicle speed. Various methods can be applied as the method of setting the above-mentioned target voltage value V _ST , and a conventionally known method may be used.

When the driver steps on the brake petal (not shown), the stop lamp switch 7 is turned on and the automatic cruise operation is canceled. After that, when the resume switch 8 is turned on, the automatic cruise operation is restarted.
Also, when the automatic transmission 11 is in the neutral shift position,
When the driving force from 10 is not transmitted to the wheel side, the automatic cruise operation is canceled to prevent the engine 10 from blowing up.

Reference numeral 15 in FIG. 1 is a hydraulic control circuit for switching the shift speed of the automatic transmission 11 according to a shift command signal from the controller 3 during auto cruise.

FIG. 2 is a flowchart showing a control procedure by the controller 3 of the constant speed traveling device, and this program is executed every time a clock pulse of a predetermined cycle is generated.

First, the controller 3 determines whether or not a timer described later is set (step S10). If this timer is not set (if the determination result is negative (N)), the process proceeds to step S30, and as described above, the current sampling value V of the voltage signal output by the throttle sensor 14 is set.
_Deviation between _TPSn and previous sampling value V _TPSn-1 (| V _TPSn-
It is determined whether V _TPSn-1 |) is greater than or equal to a first predetermined value V _X1 (for example, 0.5 V), that is, whether the throttle sensor 14 outputs an abnormal voltage.

When the throttle sensor 14 is normal, when the drive motor 5 is operated at a normal speed to drive the throttle valve 6, the above-mentioned deviation does not exceed the predetermined value V _X1 and the process proceeds to step S40. Then, the target voltage value V _ST and the operation amount of the drive motor 5 are calculated and set by the normal control described above, and it is determined again in step S50 whether or not the timer is set. Then, the operation proceeds to step S51. A drive signal corresponding to the amount is output to operate the drive motor 5 (normal output control), and the loop is terminated this time.

In step S30 described above, the current sampling value V
_{The deviation} between _TPSn and the previous sampling value V _TPSn-1 is the predetermined value V _X1
When it is determined that the throttle sensor 14 is outputting an abnormal voltage for the first time, the above-mentioned timer is set (step S31). This timer measures a predetermined time (for example, 10 seconds), starts the time measurement only after being set, and stops the time measurement when reset.

Next, in step S32, the sampling voltage value immediately before the abnormal voltage of the throttle sensor 14 is discriminated in step S30 is stored in the storage device (not shown) of the controller 3 as the immediately preceding fail voltage value V _BF . Then, after setting the flag (step S32), the pseudo current sampling value of the throttle valve opening is calculated by the following equation and set as the current sampling value V _TPSn (step S33).

V _TPSn = 2V _TPSn-1 -V _TPSn-2 where V _TPSn-2 is the sampling value of the output voltage of the throttle sensor 14 of the previous time and the previous time.

Next, the controller 3 calculates the target voltage value _VST by the above-mentioned normal control (step S40). Then, in step S50, it is determined whether or not the above-mentioned timer is set. Since the timer is set in this determination, the routine proceeds to step 52, where it is determined whether or not the flag is set. In this loop, we just set the flag in step S32, so step
In S53, the voltage increase of the throttle sensor output necessary to increase the current vehicle speed U by a predetermined value Δu (for example, 20 km / h) from the vehicle speed-throttle sensor voltage map stored in the storage device of the controller 3 Calculate ΔV _TPS .
FIG. 3 shows the relationship between the vehicle speed U and the throttle sensor voltage V _{TPS in} the vehicle speed-throttle sensor voltage map stored in the above-mentioned storage device, and more specifically, the vehicle travels at a constant speed on a normal road having an inclination of 0%. In this case, the relationship between the vehicle speed U and the output voltage V _TPS of the throttle sensor 14 corresponding to the valve opening degree of the throttle valve 6 required to maintain the vehicle speed is shown, and is detected by the vehicle speed sensor 4 from this graph. It is necessary to increase the current vehicle speed U (= U ₁ ) by a predetermined speed Δu.
An increase ΔV _TPS of the output voltage of the throttle sensor 14 is required.

Next, after clearing the flag in step S54, a unit for accelerating the speed increase amount Δu (20 km / h) for a predetermined time (10 seconds) from the voltage increase amount ΔV _TPS calculated in step S53 described above. Calculate the increment ΔV _TPS ′ (unit voltage / second) per unit time. That is, the opening speed of the throttle valve 6 is calculated (step S55). The increment ΔV _TPS ′ per unit time is stored and stored in the storage device of the controller 3. Then, it is determined whether or not the throttle valve 6 was driven in the closing direction last time, that is, whether or not the drive motor 5 was reversely driven (step S56), and if it was reversely driven, it should be driven in the same direction. The sign of the calculated increment ΔV _TPS ′ is set negative (ΔV _TPS ′ = −ΔV _TPS ′) and stored in the storage device (step S58). Then step S
Proceed to step 59 and increase the output signal value of the throttle sensor 14 by Δ
The drive motor 5 is driven for a time corresponding to V _TPS ′, the throttle valve 6 is opened or closed at a constant speed, and the loop is terminated this time.

As is clear from the relationship between the vehicle speed and the throttle sensor voltage shown in FIG. 3, these relationships are non-linear, and increase from a high vehicle speed by a predetermined value Δu and from a low vehicle speed by a predetermined value Δu. When speeding up, throttle valve 6
The valve opening increase of is different. Therefore, if the increase ΔV _TPS required to accelerate by Δu in the low vehicle speed range is calculated and applied to the high vehicle speed range, the vehicle speed will increase slowly, and conversely, in the high vehicle speed range. If the increase ΔV _TPS required to increase the vehicle speed by Δu is calculated and applied in the low vehicle speed range, the vehicle speed will be rapidly increased, and any of these will impair the driving feeling. Since the method of the present invention obtains the increase ΔV _TPS according to the detected vehicle speed, the vehicle speed is increased or decelerated at an appropriate acceleration.

The increment ΔV _TPS described above may be read according to the target vehicle speed U _ST instead of the vehicle speed U detected from FIG. Further, in the above-mentioned embodiment, the increase amount ΔV _TPS ′ of the vehicle speed is obtained, and when the throttle valve 6 is driven in the closing direction, the sign of the increase amount ΔV _TPS ′ is set to a negative value and the decrease amount is decreased. However, when the throttle valve 6 is driven in the opening direction, the predetermined value Δ from FIG.
A decrease in the output voltage of the throttle sensor 14, which is necessary to decelerate the increase ΔV _TPS of the output voltage of the throttle sensor 14 by u by a predetermined value Δu when it is driven in the valve closing direction. The amount ΔV _TPS may be obtained respectively. Further, although the above-described effect cannot be obtained, in some cases, regardless of the vehicle speed U and the target vehicle speed U _ST , the throttle valve 6 may be opened or closed at a constant speed using a predetermined value set in advance. You may

Once the timer is set, the determination in step S10 becomes affirmative (Y) in the next loop, and step S12 is executed. In this step S12, it is determined whether or not the output voltage value V _TPS of the throttle sensor 14 has returned to near the voltage value V _BF immediately before the abnormality in the output voltage was determined. In this determination, the deviation between the output voltage value V _TPS detected in the current loop and the immediately preceding voltage value V _BF is smaller than the first predetermined value V _{X1 by} the second value.
The predetermined value ΔV _X2 (for example, 0.4 V or less, that is, | V _TPS -V _BF | <ΔV _X2 is satisfied, it is determined that the throttle sensor 14 has returned to the normal state.

If the result of this determination is negative, that is, if the voltage value V _TPS has not returned to near the voltage value V _BF immediately before the failure, the process proceeds to step S14, where the output voltage value V _TPS of the throttle sensor 14 is _close to the target voltage value V _ST. It is determined whether or not it has returned. This determination is
Output voltage value V _TPS and target voltage value V detected in the loop this time
_When the deviation from _ST is less than or equal to a third predetermined determination value ΔV _X3 (for example, 0.4 V) which is smaller than the first predetermined value V _X1 ,
That is, when | V _TPS -V _ST | <ΔV _X3 holds, it is determined that the throttle sensor 14 has returned to the normal state. In addition, the above-mentioned target voltage V
_ST is set according to the actual vehicle speed U and the target vehicle speed U _ST in step S40 described above.

This determination result is also negative, that is, the voltage value V _TPS is the target voltage value.
If it has not returned to near V _ST , proceed to step S16,
Target voltage value from the above vehicle speed-throttle sensor voltage map
The pseudo vehicle speed U _ST corresponding to V _ST is read, and it is determined whether or not the actual vehicle speed U detected by the vehicle speed sensor 4 is considerably higher than this pseudo vehicle speed U _ST . This determination is made when the deviation between the actual vehicle speed U and the pseudo vehicle speed U _ST is larger than a predetermined value Δu (for example, 20 km / h), that is, when U−U _ST ≧ Δu is satisfied, the throttle sensor 14 fails. Instead, it is determined that the abnormal voltage value is detected by the driver's sudden operation of the accelerator pedal.

If this determination result is also negative, the process proceeds to step S18, and it is determined by the timer whether a predetermined time (10 seconds) has elapsed. In this determination, even if a predetermined time has elapsed from the time when the voltage abnormality of the throttle sensor 14 was detected, the determination result in each of the steps S12, S14, S16 described above is negative,
This is not a partial failure of the throttle sensor 14, but a total failure of being unable to detect the valve opening of the throttle valve 6 over the entire area thereof. It is determined that the control by the traveling device is impossible (system failure).

If the determination result in step S18 is also negative, the pseudo current sampling value V _TPSn is calculated and stored as in step S33 described above (step S20). Then, the process proceeds to step S40 described above, and the target voltage value V _ST by the normal control is set.
Is calculated and the process proceeds to step S50. Since the timer is still being set in step S50, step S52 is executed and the flag has already been cleared, so step S59
Then, the drive motor 5 is driven for a time corresponding to the increase ΔV _TPS ′ of the output signal value of the throttle sensor 14 stored in step S55 or step S58, and the throttle valve 6 is opened or closed. Valve and end the loop this time.

If the determination results in steps S12, S14, S16, and S18 are all negative, steps S40, S50, S52, and S
59 is repeatedly executed, and the throttle valve 6 is opened or closed at a constant speed.

Before the predetermined time (10 seconds) has elapsed, the throttle sensor
When the output voltage signal value of 14 deviates from the failure section and the voltage signal value V _TPS returns to the vicinity of the voltage value V _BF before the failure, that is, when the determination result of step S12 is affirmative, the controller 3 proceeds to step S13. After resetting the timer by executing, proceed to step S40 and set the target voltage value V _{ST under} normal control.
Etc. are calculated. Then, after making the determination in step S50, step S51 is executed, and the above-described normal output control of the drive motor 5 is executed. When the timer is reset, the previous sampling voltage V _TPSn-1 used for the determination at the time of execution of step S30 of the next loop is calculated in steps S32 and S20 described above, and is stored in the storage device. The sampling value is read and used.

Even if the voltage signal value V _TPS of the throttle sensor 14 does not return to the vicinity of the voltage value V _BF before the failure, but returns to the vicinity of the target voltage value V _ST , that is, if the determination result of step S14 is affirmative. Also resets the timer (step S15), determines that the output of the throttle sensor 14 has returned to the normal state, and executes the above-described normal control using the detected voltage signal value V _TPS (steps S40, S50, S51). ).

Furthermore, the actual vehicle speed U detected by the vehicle speed sensor 4 is read out from the aforementioned vehicle speed-throttle sensor voltage map in correspondence with the target voltage value V _ST before the above-mentioned predetermined time (10 seconds) has elapsed and the pseudo vehicle speed U. If it is considerably larger than _ST , that is, if the determination result of step S16 is affirmative, the timer is reset (step S17) and the normal control is restarted.

And the throttle sensor 14 does not return to the normal state,
When the above-mentioned predetermined time (10 seconds) has elapsed, the determination result of step S18 is affirmative, and it is determined that the constant speed traveling device has failed in system, that is, cannot be controlled (step S19). In this case, the controller 3 stops the constant speed traveling control and activates the alarm device 9 to warn the driver that the constant speed traveling device has failed. The alarm device 9 may be a device that lights a warning light or may emit an alarm sound. Further, the alarm device 9 may be lit while the above-mentioned timer is set to display that the abnormality of the output voltage of the throttle sensor 14 is detected.

Thus, according to the method of the present invention, the throttle sensor
Throughout the section where 14 is partially broken, the throttle valve 6
Is opened or closed at a constant speed, and when the throttle sensor 6 opens or closes and the throttle sensor 14 passes through the faulty section and the slotted sensor 14 outputs a normal signal again, normal control is resumed. It is configured so that it can be done. The state of vehicle speed control when the throttle sensor 14 partially fails will be described below in comparison with the case where the sensor 14 is normal.

First, FIG. 4 shows the vehicle speed U and the throttle valve opening (when the throttle sensor 14 normally detects the throttle valve opening, the valve opening corresponds to the throttle sensor 14).
(Indicated by the voltage value of), the vehicle speed U
When 80 km / h is reached, the set switch 2 is turned on and the target vehicle speed U _ST is set. When the accelerator pedal is released immediately after the target vehicle speed is set, the opening degree of the throttle valve 6 is once closed, but then the drive motor 5 suddenly opens the valve to a vehicle speed U of about 1.5 km / h. Although an undershoot is observed, the vehicle speed U is stably maintained at the substantially target vehicle speed.

On the other hand, FIG. 5 shows changes in the valve opening and the vehicle speed of the throttle valve 6 when the throttle sensor 14 partially fails. Target vehicle speed U _ST is 80k as in the case of Fig. 4.
It is set to m / h, the throttle sensor 14 partially fails in the vicinity of the target vehicle speed, and the throttle valve opening cannot be detected in the region sandwiched by the two dashed lines A and B in the figure. In such a case, the throttle valve 6 is released immediately after the target vehicle speed is set by the set switch 2 and the foot is released from the accelerator pedal.
The valve opening of the throttle valve 6 is once closed and then rapidly opened by the drive motor 5, but the valve opening of the throttle valve 6 is
At time t1 when the valve crosses with, the valve opening of the throttle valve 6 enters between the sensor fail areas A and B, and the throttle sensor 14 cannot detect the valve opening.

When the valve opening of the throttle valve 6 enters between the sensor fail areas A and B, the direction in which the drive motor 6 has been driven until now,
In this case, the throttle valve 6 is opened at a constant speed in the valve opening direction per unit time with an operation amount corresponding to the sensor output ΔV _TPS ′. When the sensor fail area is left at time t2, it is determined that the throttle sensor 14 is normal, and normal control is restarted. At this time, since the vehicle speed U exceeds the target vehicle speed U _ST , the throttle valve 6 is driven in the closing direction.

When the throttle valve 6 is closed and enters the sensor fail region again (at time t3), the drive motor 5 is actuated by the actuation amount corresponding to the sensor output (−ΔV _TPS ′) per unit time to the closing side this time, The throttle valve 6 is closed at a constant speed until it leaves the sensor fail region (until time t4). When returning to the normal control at time t4, the vehicle speed U is lower than the target vehicle speed U _ST this time, so the throttle valve 6 is driven in the opening direction. In this way, the throttle valve 6 is opened or closed at a constant speed in the sensor fail region, so that the vehicle speed U slightly overshoots the target vehicle speed U _ST by about 2.5 km / h, but is maintained at a substantially target vehicle speed. It

FIGS. 6 and 7 show the throttle valve opening and vehicle speed time when the auto cruise operation is once canceled because the brake petal is stepped on, and then the resume switch 8 is turned on to restart the auto cruise operation. FIG. 6 shows that when the throttle sensor 14 is normal, and FIG. 7 shows that when the sensor 14 partially fails in the sections A ′ and B ′.

When the resume switch 8 is turned on, the automatic cruise operation is restarted, and when the throttle sensor 14 is normal,
The controller 3 controls the vehicle speed as follows, for example. First, the throttle valve 6 is opened at a constant rate until the vehicle speed U reaches a constant acceleration (between t10 and t11), and when the constant acceleration is reached, the throttle valve 6 is opened so that the acceleration is maintained. Degree is controlled (between t11 and t12). Then, when the vehicle speed U reaches a value lower than the target vehicle speed U _ST by a predetermined value, the valve opening degree of the throttle valve 6 is rapidly closed so as to set the acceleration to 0 (between time points t12 to t13), and thereafter, the target value. The target voltage value V _ST is calculated according to the deviation between the vehicle speed U _ST and the actual vehicle speed U, and the operation amount of the drive motor 5 is calculated from the difference between the target voltage value V _ST and the output voltage V _TPS of the throttle sensor 14. The throttle valve 6 is set to the target voltage value.
It is opened or closed to the valve opening corresponding to V _ST .

When the throttle sensor 14 shown in FIG. 6 normally detects the throttle valve opening, the vehicle speed U is only 1.5 km / h.
After overshooting, the target vehicle speed is settled. The section indicated by the arrow in FIG. 6 is the third speed section, and the automatic transmission 11 is downshifted from the fourth speed to the third speed.

On the other hand, when the throttle sensor 14 partially fails, the target voltage value V _ST is calculated according to the deviation between the target vehicle speed U _ST and the actual vehicle speed U, and the target voltage value V _ST and the throttle The control in which the operation amount of the drive motor 5 is calculated from the difference from the output voltage of the sensor 14 is started, and at a time point t20 when the valve opening of the throttle valve 6 enters the sensor fail region, the throttle valve 6 closes at a constant speed. When the vehicle is driven in the direction and leaves the sensor fail area, the normal control is started again at time t21, and the vehicle speed is controlled in the same manner as described below with reference to FIG. Also in this case, the vehicle speed U slightly overshoots the target vehicle speed UST by about 2.5 km / h due to the delay of the control in the sensor fail section, but the vehicle speed U is maintained at the substantially target vehicle speed.

(Effects of the Invention) As described in detail above, according to the constant speed traveling control method for a vehicle of the present invention, the relationship between the vehicle speed and the voltage signal value of the throttle valve opening sensor is obtained in advance and the throttle valve opening is performed. The voltage signal output by the throttle sensor is sampled at a predetermined cycle, and it is determined whether or not the throttle valve opening sensor is outputting an abnormal voltage signal based on the deviation between the previous sampling voltage value and the current sampling voltage value. When the opening sensor outputs an abnormal voltage signal, the throttle valve is opened or closed at a constant speed, and the target is calculated from the previously determined relationship between the vehicle speed and the voltage signal value of the throttle valve opening sensor. When the pseudo vehicle speed corresponding to the voltage value is found, the actual vehicle speed is detected, and the output voltage of the throttle valve opening sensor does not return to the normal value within a predetermined time after the abnormality is detected. When the detected vehicle speed is higher than the pseudo vehicle speed by a predetermined speed or more before the predetermined time elapses, it is determined that the throttle valve opening sensor has failed and the vehicle speed control cannot be performed. Since it is determined that the voltage signal of is normal and the vehicle speed control is continued, the inconvenience that the vehicle speed control cannot be performed due to a partial failure of the throttle valve opening sensor is solved, and the vehicle speed control is continued. Further, a highly reliable vehicle speed control method can be obtained without confusing the abnormal output of the throttle sensor with the output that is suddenly changed by the driver's sudden accelerator pedal operation.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a constant speed traveling device in which the method of the present invention is executed, FIG. 2 is a flowchart showing a procedure of vehicle speed control executed by the controller 3 shown in FIG. 1, and FIG. Is a graph showing the relationship between the vehicle speed and the throttle sensor output of the data stored in the vehicle speed / throttle sensor output map. FIG. 4 shows the vehicle speed control when the throttle sensor normally detects the throttle valve opening. As an example, a graph showing changes in vehicle speed and throttle valve opening with time, FIG. 5 is the same as that in FIG. 4 because the output voltage of the throttle sensor is abnormal and the throttle valve opening cannot be partially detected. FIG. 6 is a graph showing the changes over time of the vehicle speed and the throttle valve opening when the vehicle speed is controlled at the target vehicle speed. FIG. 6 shows the resume when the throttle sensor normally detects the throttle valve opening. An example of restarting the vehicle speed control by a switch is shown, and a graph showing changes in vehicle speed and throttle valve opening with time, FIG. 7 shows that the output voltage of the throttle sensor is abnormal and the throttle valve opening cannot be partially detected. Sixth
FIG. 8 is a graph showing the change over time of the vehicle speed and the throttle valve opening when the vehicle speed control is restarted at the same target vehicle speed as in the figure, and FIG. 8 shows the change in the slot sensor output when the throttle sensor partially fails. Graph showing, and No. 9
Similar to FIG. 8, the figure is a graph showing another variation of the slot sensor output when the throttle sensor partially fails. 2 ... Set switch, 3 ... Controller, 4 ... Vehicle speed sensor, 5 ... Drive motor, 6 ... Throttle valve, 9
…… Alarm device, 10 …… Internal combustion engine.

Claims (1)

[Claims] 1. A throttle valve opening sensor for outputting a voltage signal according to a valve opening of a throttle valve of an internal combustion engine is provided, and a target corresponding to a target throttle valve opening according to a deviation between an actual vehicle speed and a target vehicle speed. A constant-speed running control of a vehicle that sets a voltage value and drives the throttle valve so that the voltage signal value detected by the throttle valve opening sensor matches the target voltage value to control the vehicle speed near the target vehicle speed. In the method, the relationship between the vehicle speed and the voltage signal value of the throttle valve opening sensor is obtained in advance, the voltage signal output by the throttle valve opening sensor is sampled at a predetermined cycle, and the previous sampling voltage value and the current sampling voltage value are sampled. And whether or not the throttle valve opening sensor outputs an abnormal voltage signal, the throttle valve opening sensor outputs an abnormal voltage signal. When the throttle valve is opened or closed at a constant speed, the pre-determined relationship between the vehicle speed and the voltage signal value of the throttle valve opening sensor is used to determine the pseudo vehicle speed corresponding to the target voltage value. If the output voltage of the throttle valve opening sensor does not return to the normal value by the time the actual vehicle speed is detected and the predetermined time elapses from the time when the abnormality is detected, the throttle valve opening sensor malfunctions and vehicle speed control is performed. On the other hand, if the detected vehicle speed is higher than the pseudo vehicle speed by a predetermined speed or more before the predetermined time elapses, it is determined that the voltage signal of the throttle valve opening sensor is normal and the vehicle speed control is performed. A constant speed traveling control method for a vehicle, characterized in that