JP2015051646A - Automatic traveling device of vehicle, vehicle and automatic traveling method of vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic traveling device of a vehicle which can reduce a fuel consumption amount without largely increasing an operation time, the vehicle and an automatic traveling method of the vehicle.SOLUTION: When it is determined that a prediction vehicle speed v1 at which the traveling of a front road FR1 is predicted as neutral inertia traveling Cat which the fuel injection of an engine 3 is stopped is not lower than a lower limit target vehicle speed Va' preset at a lower speed than a target vehicle speed V' on the basis of a road status of the front road FR1 and a vehicle status including a vehicle speed V, the traveling of the front road FR1 is set as the neutral inertia traveling C.

Description

  The present invention relates to a vehicle automatic traveling device, a vehicle, and a vehicle automatic traveling method, and more particularly, a vehicle automatic traveling device capable of automatically controlling a vehicle speed to a preset target vehicle speed. The present invention relates to a vehicle and a method for automatically driving the vehicle.

  In the conventional vehicle auto-cruise (automatic traveling control), control is performed so as to maintain the target vehicle speed regardless of changes in road gradient. For this reason, the fuel efficiency has deteriorated on a road where the road gradient frequently changes, that is, a road with so-called undulation.

  In this regard, based on the road gradient calculated from the atmospheric pressure and GPS data, the driving force or braking force transmitted from the engine to the wheels is determined by the driver's operation so that the vehicle travels while maintaining the target vehicle speed. An apparatus that adjusts without any change has been proposed (see, for example, Patent Document 1). This device performs internal accelerator control of constant speed cruise based on a highly reliable road gradient in any driving state of the vehicle.

  However, in the above-described device, as in the case of the conventional auto-cruise, since the vehicle is controlled to travel while maintaining the target vehicle speed, an unnecessary downshift is performed in order to keep the target vehicle speed. Or the chance of neutral inertia running. Therefore, the effect which avoids a fuel consumption deterioration will be limited.

JP 2006-226178 A

  The present invention has been made in view of the above-mentioned problems, and the problem is that an automatic traveling device for a vehicle, a vehicle, and a vehicle that can reduce fuel consumption without significantly increasing operation time. It is to provide an automatic driving method.

  In order to solve the above-described problems, an automatic traveling device for a vehicle according to the present invention has a target vehicle speed for performing a control of a vehicle mounted with an internal combustion engine as a target vehicle speed maintaining traveling for maintaining the vehicle speed at a preset target vehicle speed. A road for acquiring a road condition of a front road in an automatic traveling device for a vehicle, comprising maintenance traveling control means and inertial traveling control means for controlling the traveling of the vehicle to be inertial traveling with the fuel injection of the internal combustion engine stopped. A predicted vehicle speed when it is predicted that traveling on the front road is coasting based on the road status and the vehicle status; the target vehicle speed; An inertia traveling prediction unit that determines whether or not the lower limit target vehicle speed is lower than a preset lower limit target vehicle speed. The inertia traveling prediction unit is implemented so that the predicted vehicle speed is the lower limit target vehicle speed. If it is determined that no less than, and performing the coasting control unit, configured to coasting running of the road ahead.

  The forward road here is a road extending from the current position of the vehicle in the traveling direction of the vehicle, and the distance of the forward road may be determined according to the situation of the forward road. For example, if there is an uphill road on the road ahead, it is preferable to include at least the end point (vertex) of the uphill road, and it is more preferable to include the middle or end point of the downhill road starting from the end point of the uphill road.

  Moreover, the road condition acquisition means here is a means for acquiring the condition of the front road necessary for automatically driving the vehicle. For example, the current position is confirmed using a satellite positioning system, etc., and the road surface gradient, elevation, presence / absence of signals and curves are obtained from a database such as map information, and weather information is used. In this way, the road surface condition of the road ahead is inferred, and a preceding vehicle or a parallel vehicle is detected by a sensor to obtain a distance from the surrounding traveling vehicle or a vehicle speed difference. Alternatively, a travel history may be stored, and a slope, altitude, presence / absence of a signal, a curve, and the like may be acquired from the travel history.

  In addition, the vehicle status acquisition means referred to here is means for acquiring the status of the vehicle necessary for automatically driving the vehicle. For example, the vehicle speed detected by the vehicle speed sensor, the weight of the vehicle used for the output control of the internal combustion engine, the shift control of the gear stage of the transmission, the gear stage of the current transmission, and the like are acquired.

  Furthermore, the target vehicle speed here is a target value of the vehicle speed set in advance by the driver before controlling the automatic traveling of the vehicle. Further, the lower limit target vehicle speed here is based on a decrease value set in advance by the driver before controlling the automatic driving of the vehicle, and the vehicle speed of the automatic driving of the vehicle is reduced to the lower limit target vehicle speed. It is an acceptable value that can be done. For example, when the target vehicle speed is set to 80 km / h and the decrease value is set to -10 km / h, the lower limit target vehicle speed is 70 km / h.

  In addition, inertia traveling here refers to traveling with the fuel injection of the internal combustion engine stopped, neutral inertia traveling where the gear stage of the transmission is set to the neutral position, and the transmission to a predetermined gear stage. This includes the accelerator-off inertia traveling with the engine brake applied and the clutch-off inertia traveling with the clutch between the engine and the transmission disengaged. The hybrid vehicle also includes regenerative traveling that regeneratively drives the motor generator.

  According to the above configuration, when it is determined that the predicted vehicle speed when it is predicted that the driving on the front road is coasting based on the road condition and the vehicle condition is not lower than the lower limit target vehicle speed during the automatic driving of the vehicle. In addition, coasting starts regardless of whether the road ahead is an uphill road, a downhill road, or a flat road. As a result, it is possible to lengthen the travel distance by coasting during automatic traveling of the vehicle, and to reduce fuel consumption. In addition, coasting starts when it is determined that the vehicle speed does not fall below the lower limit target vehicle speed, so that the vehicle speed is not extremely slow, the operation time is not significantly increased, and the arrival time is delayed. be able to.

  Further, in the automatic traveling device for a vehicle described above, when the predicted vehicle speed in the inertia traveling prediction means is lower than the lower limit target vehicle speed, or when the vehicle speed falls below the lower limit target vehicle speed during the execution of the inertia traveling control means. It is desirable that the target vehicle speed maintaining travel control means is implemented so that the vehicle speed approaches the target vehicle speed.

  For example, when the predicted vehicle speed in the inertia traveling prediction means is lower than the lower limit target vehicle speed, it is possible to avoid a significant increase in operation time by switching to the target vehicle speed maintenance traveling. Also, contrary to the prediction by the inertial traveling prediction means, when the vehicle speed during inertial traveling falls below the lower limit target vehicle speed, switching to the target vehicle speed maintaining traveling can avoid a significant increase in operation time. it can.

  In addition, in the automatic traveling device for a vehicle described above, the prediction is performed so that the predicted vehicle speed in the inertial traveling prediction means falls between the upper limit target vehicle speed and the lower limit target vehicle speed that are set in advance to be higher than the target vehicle speed. The inertial traveling selection means for selecting the inertial traveling in the vehicle from either a braking inertial traveling that applies a braking force to the traveling of the vehicle or a non-braking inertial traveling that does not apply a braking force to the traveling of the vehicle, It is desirable that the inertia traveling when the traveling control means is implemented is configured to be one of the braking inertia traveling and the non-braking inertia traveling selected by the inertia traveling selecting means.

  According to this configuration, the inertial traveling in which the fuel injection of the internal combustion engine is stopped is maintained by switching between the braking inertial traveling and the non-braking inertial traveling so that the predicted vehicle speed falls between the upper limit target vehicle speed and the lower limit target vehicle speed. The possible travel distance can be increased.

  For example, if the predicted vehicle speed when the downhill road is predicted to be unbraking inertial traveling exceeds the upper limit target vehicle speed, the braking inertial traveling is selected as the inertial traveling being predicted, and re-prediction is performed. Since the braking force is applied to the vehicle in the braking inertia traveling, the vehicle speed is reduced compared to the non-braking inertia traveling. Therefore, the predicted vehicle speed when it is predicted that the traveling on the road ahead is the braking inertial traveling will not exceed the upper limit target vehicle speed, and in that case, the inertial traveling can be performed at a longer distance by performing the braking inertial traveling. it can.

  If the predicted vehicle speed when it is predicted that the downhill road is braked coasting is less than the lower limit target vehicle speed, non-braking coasting is selected for the coasting that is being predicted and is predicted again. Since the braking force is not applied to the vehicle in the non-braking inertia traveling, the vehicle speed is not reduced as compared with the braking inertia traveling. Therefore, the predicted vehicle speed when it is predicted that traveling on the front road will be unbraking coasting will not fall below the lower limit target vehicle speed. In that case, coasting coasting will be performed at a longer distance by performing unbraking coasting. Can do.

  Note that the braking inertia traveling here refers to inertia traveling that applies a braking force to the traveling of the vehicle, and refers to, for example, accelerator-off inertia traveling with an engine brake applied. Non-braking coasting refers to coasting that does not apply braking force to the vehicle, such as neutral coasting when the engine brake is not applied, or when the engine is separated from the drive shaft by the clutch. This means that the clutch is free running. Further, in the case of a hybrid vehicle including both an internal combustion engine and a motor generator, regenerative inertia that gives resistance to vehicle travel by generating power by driving the motor generator regeneratively instead of accelerator-off inertia traveling. You may run.

  Furthermore, in the above-described automatic traveling device for a vehicle, when the coasting prediction unit predicts that traveling on a road ahead with a downhill road after an uphill road is coasting based on the road condition and the vehicle condition. , And means for determining whether or not the predicted vehicle speed is below the lower limit target vehicle speed until the vehicle reaches the downhill road, and the inertial traveling prediction means is implemented, and the prediction is performed until the vehicle reaches the downhill road. When it is determined that the vehicle speed does not fall below the lower limit target vehicle speed, it is preferable that the inertial traveling control means is implemented from an uphill road.

  According to this configuration, when traveling ahead of the top of the uphill road, it is predicted that traveling on the front road with a downhill road having a descending slope capable of gravity acceleration after the uphill road is assumed to be coasting on the front road. When it is determined that the predicted vehicle speed does not fall below the lower limit target vehicle speed before reaching the downhill road, coasting is performed from the uphill road just before the top. As a result, coasting can be carried out to the descending slope through the top of the uphill road, and the travel distance by the coasting can be increased, so that the fuel consumption can be reduced.

  In addition, even if coasting on such a road is coasting, the vehicle speed does not fall below the lower limit target vehicle speed, so the coasting time does not significantly increase the operation time and avoids delaying the arrival time. The amount can be reduced.

  And the vehicle of this invention for solving said subject is comprised including the automatic travel apparatus of the vehicle as described above. According to this configuration, it is possible to reduce the fuel consumption by increasing the traveling opportunity by inertial traveling in which the fuel injection of the internal combustion engine is stopped, and to set the vehicle speed during the inertial traveling to the upper limit target vehicle speed and the lower limit based on the target vehicle speed. Since it falls within the target vehicle speed, it is possible to avoid a significant increase in operation time even if the chance of coasting increases.

  Then, the vehicle automatic traveling method of the present invention for solving the above-described problems is a vehicle automatic operation in which the traveling of the vehicle equipped with the internal combustion engine is set to the target vehicle speed maintaining traveling that maintains the vehicle speed at a preset target vehicle speed. In the traveling method, the predicted vehicle speed when the traveling on the front road is predicted to be inertial traveling in which the fuel injection of the internal combustion engine is stopped is based on the road condition on the front road and the vehicle condition including the vehicle speed. In this method, when it is determined that the vehicle speed is lower than the lower limit target vehicle speed set in advance at a speed slower than the vehicle speed, traveling on the front road is made inertial.

  Further, in the above vehicle automatic traveling method, when the predicted vehicle speed falls below the lower limit target vehicle speed, or when the vehicle speed during inertial travel falls below the lower limit target vehicle speed, the vehicle travels from inertial travel to maintain the target vehicle speed. It is desirable to switch to running.

  In addition, in the above-described automatic vehicle traveling method, the inertial traveling under prediction is performed such that the predicted vehicle speed falls between the upper limit target vehicle speed and the lower limit target vehicle speed that are set in advance to be higher than the target vehicle speed. The selected braking inertial traveling is selected from either a braking inertial traveling that applies a braking force to the traveling of the vehicle or an unbraking inertial traveling that does not apply a braking force to the traveling of the vehicle. And either one of the non-braking coasting and the above-mentioned.

  Further, in the above vehicle automatic traveling method, when it is predicted that traveling on a front road having a downhill road after an uphill road is an inertial road based on the road condition and the vehicle condition, the vehicle enters the downhill road. When it is determined that the predicted vehicle speed does not fall below the lower limit target vehicle speed before reaching the vehicle, it is desirable to start coasting from an uphill road.

  According to the vehicle automatic traveling device, the vehicle, and the vehicle automatic traveling method of the present invention, in the automatic traveling of the vehicle, the case where the vehicle travels on the road ahead is predicted, and the vehicle speed to be increased or decreased by the inertia traveling is a predetermined upper limit target. Driving by inertial driving that starts inertial driving and stops fuel injection of the internal combustion engine regardless of whether the road ahead is uphill, downhill or flat when it is determined that the vehicle speed falls within the lower limit target vehicle speed The distance can be increased.

  As a result, it is possible to reduce the fuel consumption by increasing the driving opportunity by the inertial running in which the fuel injection of the internal combustion engine is stopped, and to change the vehicle speed during the inertial running between the upper limit target vehicle speed and the lower limit target vehicle speed based on the target vehicle speed. Therefore, even if the chance of coasting increases, it is possible to avoid delaying the arrival time without significantly increasing the operation time.

It is a figure which shows the structure of the automatic traveling apparatus of the vehicle of embodiment which concerns on this invention. It is a flowchart which shows the inertia running prediction means of FIG. It is a figure which shows the 1st example of the automatic traveling method of embodiment which concerns on this invention. It is a figure which shows the 2nd example of the automatic traveling method of embodiment which concerns on this invention. It is a figure which shows the 3rd example of the automatic traveling method of embodiment which concerns on this invention. It is a figure which shows the 4th example of the automatic traveling method of embodiment which concerns on this invention.

  Hereinafter, an automatic traveling device for a vehicle and an automatic traveling method for a vehicle according to embodiments of the present invention will be described.

  In FIG. 1, the engine 3 is described as an in-line six-cylinder diesel engine, but the present invention can also be applied to a gasoline engine, and the number and arrangement of the cylinders are not particularly limited. Moreover, although the vehicle 1 is demonstrated as an example of large vehicles, such as a truck carrying a diesel engine, this invention is not limited to large vehicles, such as a truck.

In addition, in the following, when described as coasting without a reference sign, it includes unbraking coasting and braking coasting. Further, as a non-braking inertia traveling without applying a braking force to the vehicle, a neutral inertia traveling with the gear stage of the transmission 5 shifted to neutral is C _NEU , while as a braking force applying inertia traveling to apply a braking force to the vehicle, the engine Accelerator-off inertia traveling that applies braking force to the vehicle by braking is distinguished as C _OFF .

  Further, in the following, symbols FR1 to FR8 are assigned to the road ahead. For example, assuming that the current position of the vehicle 1 in FIG. 3 is a point A, the forward road FR1 is a road from the point A to the point C. Further, assuming that the current position of the vehicle 1 in FIG. 5 is a K point, the forward road FR6 is a road from the K point to the M point.

  As shown in FIG. 1, in the vehicle 1 on which the automatic travel device 2 of this embodiment is mounted, the power of the engine 3 is transmitted to the transmission (transmission) 5 via the clutch 4, and further, It is transmitted from the machine 5 to an operating device (differential gear) 7 through a propulsion shaft (propeller shaft) 6, and transmitted from the operating device 7 to a wheel 9 through a drive shaft (drive shaft) 8. Thereby, the motive power of the engine 3 is transmitted to the wheels 9 and the vehicle 1 travels.

  The automatic travel device 2 according to this embodiment is a device that automatically controls the output of the engine 3, the connection / disconnection of the clutch 4, and the speed change of the transmission 5 to cause the vehicle 1 to travel automatically. Is controlling. The control device includes an engine ECU (engine control device) 10 that controls the output of the engine 3, and a power transmission ECU (power transmission control device) 11 that controls the connection and disconnection of the clutch 4 and the shift of the transmission 5. And an automatic travel control device 12 for controlling the automatic travel of the vehicle 1. The engine ECU 10, the power transmission ECU 11, and the automatic travel control device 12 are microcontrollers that perform electrical control in charge of each by an electric circuit. The engine ECU 10, the power transmission ECU 11, and the automatic travel control device 12 are connected to each other via an in-vehicle network, and communicate necessary data and control signals with each other.

  The automatic travel device 2 includes a target vehicle speed setting device 13 and an increase / decrease value setting device 14 on a dashboard (not shown). The target vehicle speed setting device 13 and the increase / decrease value setting device 14 are connected to the automatic travel control device 12. The

  This target vehicle speed setting device 13 is a device that is operated by the driver before the automatic traveling of the vehicle 1 is started, and sets a target vehicle speed V ′ when the vehicle 1 is automatically traveling. When the target vehicle speed V ′ is set in the target vehicle speed setting device 13 by the driver, the target vehicle speed V ′ is transmitted to the automatic travel control device 12 and stored in the automatic travel control device 12.

  Further, the increase / decrease value setting device 14 is operated by the driver before the automatic travel of the vehicle 1 is started and after the target vehicle speed V ′ is set, so that the speed decrease value during the automatic travel of the vehicle 1− It is a device in which both va and the speed increase value + vb are set. When both the speed decrease value -va and the speed increase value + vb are set in the increase / decrease value setting device 14 by the driver, the speed decrease value -va and the speed increase value + vb are transmitted to the automatic travel control device 12, and the automatic travel is performed. It is stored in the control device 12. Then, the lower limit target vehicle speed Va 'and the upper limit target vehicle speed Vb' are calculated by adding each of the speed decrease value -va and the speed increase value + vb to the target vehicle speed V 'and stored.

  The target vehicle speed V ', the speed decrease value -va and the speed increase value + vb can be set to arbitrary values separately by the driver. For example, when the target vehicle speed V ′ is 80 km / h, the speed decrease value −va is −5 km / h, and the speed increase value + vb is +10 km / h, the lower limit target vehicle speed Va ′ is 75 km / h, and the upper limit The target vehicle speed Vb ′ is 90 km / h. The speed decrease value -va and the speed increase value + vb may be set to zero.

  The lower limit target vehicle speed Va ′ and the upper limit target vehicle speed Vb ′ are within a range of the vehicle speed V that can be allowed by the driver when the vehicle 1 is automatically driven.

  The automatic traveling device 2 includes a road condition acquisition device 20 and a vehicle condition acquisition device 30, and the automatic traveling control device 12 uses these devices to acquire road condition acquisition means M1 for acquiring the road condition of the road ahead. And vehicle condition acquisition means M2 for acquiring the vehicle condition of the vehicle 1, and inertia traveling prediction means M3 for predicting a case where the vehicle travels on the front road based on the road condition and the vehicle condition of the front road. It comprises inertial traveling control means M4 for controlling inertial traveling according to the predicting means M3 and target vehicle speed maintaining traveling control means M5 for controlling target vehicle speed maintaining traveling.

  The road condition acquisition device 20 is a device for determining a road ahead and acquiring the road condition of the road ahead. In this embodiment, as an example, the current road condition acquisition device 20 is a communication device with a satellite positioning system (GPS). A position acquisition device 21, a weather acquisition device 22 that acquires the weather during traveling, and a surrounding sensor 23 that detects a distance and a vehicle speed difference from surrounding traveling vehicles such as a preceding vehicle and a parallel running vehicle.

  The road condition acquisition means M1 for acquiring the road condition of the front road using the road condition acquisition device 20 determines the front road and acquires information necessary for automatically driving the vehicle 1 on the front road. It is. Specifically, the front road is determined from the map data stored in advance from the current position acquired by the current position acquisition device 21, and the road gradient of the acquired front road and the curve and signal provided on the front road are acquired. Get presence or absence. Moreover, the road surface condition (an frozen road surface, a flooded road surface, etc.) of the front road estimated from the current weather condition acquired from the weather acquisition apparatus 22 is acquired. In addition, it is a means for acquiring a distance from the surrounding traveling vehicle, a vehicle speed difference, and the like from information detected by the surrounding sensor 23.

  It should be noted that the length of the section of this road ahead may be determined according to the linearity (gradient or curve). For example, the front road FR1 shown in FIG. 3 may include at least the point A to the end point (top) of the uphill road, and preferably includes the point A to the point C via the end point of the uphill road. Further, when the downhill road continues to some extent as in the forward road FR5 shown in FIG. 5, it is desirable to include the end point of the downhill road.

  The vehicle status acquisition device 30 is a device for acquiring the vehicle status of the vehicle 1. In this embodiment, as an example, an accelerator pedal 31, a brake pedal 32, a shift lever 33, a turn signal switch 34, and the vehicle 1 are used. A vehicle speed sensor 35 for detecting the vehicle speed V of the vehicle is included. The engine ECU 10 and the power transmission ECU 11 are also a kind of the vehicle status acquisition device 30.

  The vehicle status acquisition means M2 for acquiring the vehicle status of the vehicle 1 using the vehicle status acquisition device 30 is a means for acquiring information necessary for automatically driving the vehicle 1. Specifically, the vehicle speed V detected by the vehicle speed sensor 35, the operation of the accelerator pedal 31, the brake pedal 32, the shift lever 33, the turn signal switch 34, and the like, and the engine 3 used in the engine ECU 10 and the power transmission ECU 11 This is means for obtaining output information, the weight W of the vehicle 1, and the gear stage of the transmission 5.

  Note that the road condition acquisition unit M1 and the vehicle condition acquisition unit M2 are not limited to the above-described configurations, and can use well-known techniques, respectively, and the road condition acquisition device 20 and the vehicle condition acquisition device according to the information to be acquired. The apparatus provided in 30 can be changed or increased.

  The inertia traveling prediction means M3 determines whether or not the predicted vehicle speed when it is predicted that the traveling on the front road is inertial traveling is lower than the lower limit target vehicle speed Va ′ based on the road condition and the vehicle condition. The inertial travel control means M4 is executed when the target vehicle speed Va ′ is not lower than the target vehicle speed Va ′, and the target vehicle speed maintenance travel control means M5 is executed when the predicted vehicle speed is lower than the lower limit target vehicle speed Va ′.

  Specifically, it is determined whether or not the predicted vehicle speed when it is predicted that traveling on the front road is coasting is between the upper limit target vehicle speed Vb ′ and the lower limit target vehicle speed Va ′, and the predicted vehicle speed is the lower limit target vehicle speed Va. If it falls within the range between 'and the upper limit target vehicle speed Vb', the inertial running control means M4 is implemented. If the predicted vehicle speed does not fall between the lower limit target vehicle speed Va 'and the upper limit target vehicle speed Vb', the target vehicle speed maintaining running control is performed. Means for implementing the means M5.

The inertial traveling prediction means M3 controls the inertial traveling being predicted to travel of the vehicle 1 so that the predicted vehicle speed in the inertial traveling prediction means M3 falls between the lower limit target vehicle speed Va ′ and the upper limit target vehicle speed Vb ′. Inertia traveling selection means for selecting either one of accelerator off inertial traveling C _OFF (braking inertial traveling) to which power is applied and neutral inertia traveling C _NEU (unbraking inertial traveling) in which braking force is not applied to the traveling of the vehicle 1 It is configured with M6.

This inertial travel selection means M6, if the predicted vehicle speed when the inertial travel being predicted is neutral inertial travel _CNEU does not fall between the lower limit target vehicle speed Va ′ and the upper limit target vehicle speed Vb ′, When the accelerator-off inertia traveling C _OFF is selected as the vehicle speed or the predicted inertia traveling is set to the accelerator-off inertia traveling C _OFF , the predicted vehicle speed does not fall between the lower limit target vehicle speed Va ′ and the upper limit target vehicle speed Vb ′. This is means for selecting the neutral inertia traveling C _NEU as the inertia inertia traveling being predicted.

If the inertia traveling selection means M6 is performed during the inertial traveling prediction means M3, the accelerator off inertia traveling C _OFF and the neutral inertia traveling C _NEU selected by the inertia traveling selecting means M6 are performed again on the road ahead. Predict the case of either one.

  An example of the inertia running prediction means M3 will be described with reference to the flowchart shown in FIG. The flowchart shown in FIG. 2 is an example in the case where the target vehicle speed maintaining traveling is performed, and the inertia traveling prediction means M3 of the present invention is not limited to this.

  First, the road condition acquisition means M1 performs step S10 for determining a road ahead. Next, step S20 which acquires the road condition of a front road is performed. Next, the vehicle status acquisition means M2 performs step S30 for acquiring the vehicle status.

Next, the inertia traveling prediction means M3 performs step S40 for predicting the case where the traveling on the front road is set to the neutral inertia traveling C _NEU based on the acquired road condition and vehicle condition. Next, step S50 is performed to determine whether or not the predicted vehicle speed falls between the lower limit target vehicle speed Va ′ and the upper limit target vehicle speed Vb ′. If it is determined in this step S50 that the predicted vehicle speed falls between the lower limit target vehicle speed Va ′ and the upper limit target vehicle speed Vb ′, then the inertial running control means M4 is executed, and the neutral inertial running C _NEU is started. To complete.

If it is determined in step S50 that the predicted vehicle speed does not fall between the lower limit target vehicle speed Va ′ and the upper limit target vehicle speed Vb ′, then the inertia traveling selection means M6 is executed to select the accelerator-off inertia traveling C _OFF. S70 is performed. Next, step S80 for predicting the case where the traveling on the road ahead is the accelerator-off inertia traveling C _OFF is performed. Next, step S90 for determining whether or not the predicted vehicle speed falls between the lower limit target vehicle speed Va ′ and the upper limit target vehicle speed Vb ′ is performed. In this step S90, the prediction vehicle speed is determined to fall between the lower limit target vehicle speed Va 'as the upper limit target vehicle speed Vb', then, by implementing the coasting control means M4, starts the accelerator-off coasting C _OFF step Complete S100.

  If it is determined in step S90 that the predicted vehicle speed does not fall between the lower limit target vehicle speed Va ′ and the upper limit target vehicle speed Vb ′, then the target vehicle speed maintenance running control means M5 is executed to start the target vehicle speed maintenance running. Perform S110 to complete.

In addition, when said inertial running prediction means M3 is implemented during the accelerator off inertial running C _OFF , for example, Step S40 and Step S60 are replaced with Step S80 and Step S100, and Step S70 is replaced. The neutral inertia running C _NEU may be selected.

  The inertial traveling control means M4 is the inertial traveling predicting means M3, and it is determined that the predicted vehicle speed does not fall below the lower limit target vehicle speed Va ′. Specifically, the predicted vehicle speed is determined to be within the lower limit target vehicle speed Va ′ and the upper limit target vehicle speed Vb ′. In this case, it is means for performing control so that traveling on the road ahead is coasting with the fuel injection of the engine 3 stopped. The control that sets the traveling on the road ahead as the inertia traveling is a control that sends an instruction to the engine ECU 10 to stop the fuel injection of the engine 3.

Further, when the inertia traveling selection means M6 is implemented by the inertia traveling prediction means M3, in addition to the control for sending an instruction to the engine ECU 10 to stop the fuel injection of the engine 3, the inertia traveling selection means M6 selects In accordance with either the accelerator-off inertia traveling C _OFF or the neutral inertia traveling C _NEU , control for sending an instruction to shift the transmission 5 to either neutral or a predetermined gear stage is added.

In addition, the coasting control means M4 is coasting to maintain the maximum vehicle speed V _MAX not exceeding 'upper limit target vehicle speed Vb is set to a speed faster than' the vehicle speed V in the accelerator-off coasting C _OFF target vehicle speed V A maximum vehicle speed maintaining means M7 is provided.

Specifically, the inertia traveling maximum vehicle speed maintaining means M7 shifts the gear stage of the transmission 5 shown in FIG. 1 to the optimum position for the maximum vehicle speed V _MAX and applies a braking force to the vehicle 1 by the braking device 40. This is means for maintaining the maximum vehicle speed V _MAX so that the vehicle speed V during coasting does not exceed the upper limit target vehicle speed Vb ′.

This inertial traveling maximum vehicle speed maintaining means M7 is configured to set the gear stage of the transmission 5 to an optimum gear stage that maintains the vehicle speed V at the maximum vehicle speed V _MAX based on the road condition of the road ahead and the vehicle condition. Control instructing the transmission ECU 11 is performed. Moreover, this inertial traveling maximum vehicle speed maintenance means M7 performs control which operates the braking device 40 based on the road condition and vehicle condition of a front road.

As the braking device 40, there are a foot brake 41, a retarder 42, and an auxiliary brake 43 such as an exhaust brake controlled by the engine ECU 10 or the power transmission ECU 11, and the magnitude of the braking force decreases in order. Therefore, the inertia traveling maximum vehicle speed maintaining means M7 uses one or a plurality of exhaust brakes of the foot brake 41, the retarder 42, and the auxiliary brake 43 according to the road condition and the vehicle condition of the front road. Thus, each braking device 40 is controlled so that the vehicle speed V during the accelerator-off inertia traveling C _OFF is maintained at the maximum vehicle speed V _MAX .

  The target vehicle speed maintenance travel control means M5 is inertial travel prediction means M3, and the predicted vehicle speed is less than the lower limit target vehicle speed Va ′. Specifically, the predicted vehicle speed must be within the lower limit target vehicle speed Va ′ and the upper limit target vehicle speed Vb ′. When the determination is made, the vehicle speed V is made closer to the target vehicle speed V ′ by controlling the traveling on the road ahead to be the target vehicle speed maintaining traveling.

  In addition, the vehicle speed V during inertial traveling during the inertial traveling control means M4 is lower than the lower limit target vehicle speed Va ′. Specifically, the vehicle speed does not fall between the lower limit target vehicle speed Va ′ and the upper limit target vehicle speed Vb ′. In addition, the vehicle speed V is made closer to the target vehicle speed V ′ by performing a control for making the traveling on the road ahead the target vehicle speed maintaining traveling.

  The control for setting the target vehicle speed to maintain the traveling on the road ahead is performed when the predicted vehicle speed is determined to be lower than the lower limit target vehicle speed Va ′ and when the vehicle speed V during inertial traveling is lower than the lower limit target vehicle speed Va ′. In this control, an instruction is sent to the ECU 10 to start fuel injection of the engine 3, and an instruction is sent to set the gear stage of the transmission 5 to a predetermined gear stage. As a result, the output of the engine 3 is transmitted to the wheels 9, and the vehicle speed V is increased to approach the target vehicle speed V '.

  On the other hand, in the control in which the traveling on the road ahead is the target vehicle speed maintaining traveling, when the predicted vehicle speed is determined to exceed the upper limit target vehicle speed Vb ′, and when the vehicle speed V during inertial traveling exceeds the upper limit target vehicle speed Vb ′. The control uses the braking device 40. In this case, while maintaining inertial running, each braking device 40 is controlled to apply a braking force to the vehicle 1 to decrease the vehicle speed V and bring it closer to the target vehicle speed V ′.

  And the automatic traveling method of the vehicle 1 of embodiment which concerns on this invention is based on the road condition of a front road, and the vehicle condition containing a vehicle speed, and the prediction vehicle speed at the time of estimating driving | running | working on a front road as inertial driving | running | working In this method, when it is determined that the vehicle speed does not fall below the lower limit target vehicle speed Va ′, traveling on the road ahead is coasting.

  The automatic traveling method of the vehicle 1 will be described with reference to FIGS.

As shown in FIG. 3, the current position of the vehicle 1 is set as a point A, and the target vehicle speed maintaining traveling control means M5 is already executed in front of the point Z, so that the vehicle 1 is traveling as the target vehicle speed maintaining traveling. And A forward road FR1 from point A to point C is a road with a downhill road after an uphill road. When coasting travel prediction means M3 is performed at point A, it is assumed that both the uphill road and downhill road of the front road FR1 are assumed to be neutral coasting C _NEU based on the road condition of the front road FR1 and the vehicle situation of the vehicle 1. It is determined whether or not the predicted vehicle speed v1 falls between the lower limit target vehicle speed Va ′ and the upper limit target vehicle speed Vb ′.

Actually, since acceleration due to gravitational acceleration is expected on the downhill road of the front road FR1, the predicted vehicle speed that is reduced by the neutral coasting C _NEU before reaching the downhill road of the front road FR1, that is, until reaching the point B. It is determined whether or not v1 is lower than the lower limit target vehicle speed Va ′. Then, when it is determined that the predicted vehicle speed v1 does not fall below the lower limit target vehicle speed Va ′, the inertia traveling control means M4 is performed to set the traveling on the front road FR1 as the neutral inertia traveling C _NEU .

Further, the forward road FR2 from the point C to the point D is a downhill road. When the inertia traveling prediction means M3 is performed at the point C, it is determined that the predicted vehicle speed v2 when the forward road FR2 is predicted to be the neutral inertia traveling C _NEU exceeds the upper limit target vehicle speed Vb ′. Then, the target vehicle speed maintaining traveling control means M5 is implemented to set the traveling on the front road FR2 as the target vehicle speed maintaining traveling.

At this time, since it is determined that the predicted vehicle speed v2 exceeds the upper limit target vehicle speed Vb ′, the neutral inertia traveling C _NEU is terminated and switched to the accelerator-off inertia traveling C _OFF where the engine brake is applied. Then, while maintaining the accelerator-off coasting C _OFF, performs control to use the brake device 40. The control using this braking device 40 is a control signal for sending a control signal for closing a shutter valve provided in an exhaust passage (not shown) to the engine ECU 10 and for shifting the gear stage from neutral to a predetermined gear stage to the power transmission ECU 11. Or a control for applying a load to the vehicle 1 from the foot brake 41 and the retarder 42. As a result, braking by the braking device 40 is started, the vehicle speed V decreases, and approaches the target vehicle speed V ′.

  Therefore, in FIG. 3, a section L1 is a section that consumes fuel and applies driving force to the vehicle 1, and a section L2 is a section that alternately converts gravity potential energy and kinetic energy without consuming fuel. The section L3 is a section in which the gravitational potential energy is converted into kinetic energy and the braking force is applied to the vehicle 1 without consuming fuel.

As shown in FIG. 4, the front road FR3 from the point E to the point I is a road having a downhill road after an uphill road. The predicted vehicle speed v3 when the inertia traveling prediction means M3 is performed at the point E and the traveling on the front road FR3 is predicted to be the neutral inertia traveling C _NEU falls between the lower limit target vehicle speed Va ′ and the upper limit target vehicle speed Vb ′. Judge. Next, the inertia traveling control means M4 is implemented, and the traveling on the front road FR3 is set as the neutral inertia traveling _CNEU .

Neutral coasting C At point F in _NEU , contrary to the prediction made by coasting traveling prediction means M3, the speed of the preceding vehicle traveling in front of the vehicle 1 is slow and the vehicle 1 approaches the preceding vehicle When the vehicle speed is excessive, control for temporarily reducing the vehicle speed V of the vehicle 1 is performed, and at the point G, the vehicle speed V falls below the lower limit target vehicle speed Va ′.

At this time, the target vehicle speed maintaining traveling control means M5 is implemented, the neutral inertia traveling _CNEU is terminated, and the target vehicle speed maintaining traveling is started. Since the vehicle speed V is lower than the lower limit target vehicle speed Va ′, fuel injection is performed on the engine 3 to start the engine 3. As a result, the power of the engine 3 is transmitted to the wheels 9 and the vehicle speed V approaches the target vehicle speed V ′.

The forward road FR4 from the H point to the I point is a downhill road. The predicted vehicle speed v4 when the inertia traveling prediction means M3 is performed at the point H and the traveling on the front road FR4 is predicted to be the neutral inertia traveling C _NEU falls between the lower limit target vehicle speed Va ′ and the upper limit target vehicle speed Vb ′. Judge. Next, the inertia traveling control means M4 is implemented, and the traveling on the front road FR4 is set as the neutral inertia traveling _CNEU .

In addition, the forward road FR5 from point I to point J is a downhill road. The inertia traveling prediction means M3 is performed at the point I, and it is determined that the predicted vehicle speed v5a when it is predicted that the traveling on the front road FR5 is the neutral inertia traveling C _NEU exceeds the upper limit target vehicle speed Vb ′. At this time, the inertia traveling selection means M6 is implemented to select the accelerator-off inertia traveling C _OFF , and the prediction is performed again. The re-prediction, the prediction speed v5b when it is predicted that the travel of the road ahead FR5 the accelerator pedal coasting C _OFF is judged not exceed the upper limit target vehicle speed Vb '. Then conducted coasting control means M4 from I point, the accelerator-off coasting C _OFF the driving of the road ahead FR5.

  Therefore, in FIG. 4, a section L4 is a section that consumes fuel and applies driving force to the vehicle 1, and a section L5 is a section that converts kinetic energy to gravity potential energy without consuming fuel, and a section. L6 is a section where fuel is consumed and driving force is applied to the vehicle 1, section L7 is a section where gravity potential energy is converted into kinetic energy without consuming fuel, and section L8 is not consuming fuel. In addition, the gravity potential energy is converted into kinetic energy and a braking force is applied to the vehicle 1.

As shown in FIG. 5, the current position of the vehicle 1 is set as the K point, and the accelerator off coasting traveling C _OFF is already performed in front of the Z point, and the vehicle speed V is the highest by the coasting traveling maximum vehicle speed maintaining means M7. It is assumed that the vehicle speed is maintained at V _MAX . The forward road FR6 from the K point to the M point is a downhill road whose gradient gradually decreases. At point K, the inertia traveling prediction means M3 is implemented, and it is determined that the predicted vehicle speed v6a when it is predicted that the traveling on the front road FR6 is the accelerator-off inertia traveling C _OFF is lower than the lower limit target vehicle speed Va ′. At this time, the inertial traveling selection means M6 is performed to select the neutral inertial traveling C _NEU as the inertial traveling, and the prediction is performed again. In the re-prediction, it is determined that the predicted vehicle speed v6b when it is predicted that the traveling on the front road FR6 is the neutral inertia traveling C _NEU does not fall below the lower limit target vehicle speed Va ′. Then, the coasting traveling control means M4 is performed from the point K, and traveling on the front road FR6 is set as the neutral coasting traveling C _NEU .

A forward road FR7 passing from the M point to the N point is a substantially flat road. The inertia traveling prediction means M3 is performed at the N point, and it is determined that the predicted vehicle speed v7a when the traveling on the front road FR7 is predicted to be the neutral inertia traveling C _NEU is lower than the lower limit target vehicle speed Va ′. Next, the inertia traveling selection means M6 is implemented, and it is determined that the predicted vehicle speed v7b when it is predicted that traveling on the front road FR7 is accelerator-off inertia traveling C _OFF is lower than the lower limit target vehicle speed Va ′. Next, the target vehicle speed maintaining traveling control means M5 is implemented to set the traveling on the front road FR7 as the target vehicle speed maintaining traveling. Since it is a case where it is judged that the predicted vehicle speeds v7a and v7b are lower than the lower limit target vehicle speed Va ′, the engine 3 is driven to bring the vehicle speed V closer to the target vehicle speed V ′.

  Therefore, in FIG. 5, the section L9 is a section in which the gravity potential energy is converted into kinetic energy without consuming fuel, and the braking force is applied to the vehicle 1, and the section L10 is in the gravity potential without consuming fuel. In the section in which energy is converted into kinetic energy, the section L11 is a section in which fuel is consumed and driving force is applied to the vehicle 1.

As shown in FIG. 6, the current position of the vehicle 1 is set as the O point, and the accelerator off inertia traveling C _OFF is already performed in front of the Z point, and the vehicle speed V is the highest by the inertia traveling maximum vehicle speed maintaining means M7. It is assumed that the vehicle speed is maintained at V _MAX . The forward road FR8 passing from the point O to the point R is a road having a flat road after a downhill road whose gradient gradually decreases. At the point O, the inertia traveling prediction means M3 is implemented, and it is determined that the predicted vehicle speed v8a when it is predicted that the traveling on the front road FR8 is the accelerator-off inertia traveling C _OFF is lower than the lower limit target vehicle speed Va ′. At this time, the inertia travel selection means M6 is performed, and the neutral inertia travel C _NEU is selected as the inertia travel, and the prediction is performed again. In the re-prediction, it is determined that the predicted vehicle speed v8b when it is predicted that the traveling on the front road FR8 is the neutral inertia traveling C _NEU does not fall below the lower limit target vehicle speed Va ′. Then, the inertia traveling control means M4 is performed from the point O, and the traveling on the front road FR8 is set as the neutral inertia traveling C _NEU .

  Therefore, in FIG. 6, the section L12 is a section in which the gravity potential energy is converted into kinetic energy without consuming fuel, and the braking force is applied to the vehicle 1, and the section L13 is in the gravity potential without consuming fuel. It becomes the section which converts energy into kinetic energy.

  According to the automatic travel device 2 of the above embodiment, the vehicle 1 including the same, and the automatic travel method thereof, during the automatic travel of the vehicle 1, the travel on the front road is coasted based on the road condition and the vehicle condition. Then, when it is determined that the predicted vehicle speed when predicted is not lower than the lower limit target vehicle speed Va ′, coasting is started regardless of whether the road ahead is an uphill road, a downhill road, or a flat road. As a result, it is possible to lengthen the travel distance by coasting while the vehicle 1 is traveling automatically, and to reduce fuel consumption. Furthermore, since coasting is started when it is determined that the vehicle speed V does not fall below the lower limit target vehicle speed Va ′, the vehicle speed V is not extremely slow, the operation time is not significantly increased, and the arrival time is delayed. You can avoid that.

Further, when the inertia traveling prediction means M3 predicts the inertia inertia traveling being predicted as the neutral inertia traveling C _NEU , the prediction is made when the predicted vehicle speed does not fall between the lower limit target vehicle speed Va ′ and the upper limit target vehicle speed Vb ′. The inertia traveling in the middle is switched to the accelerator-off inertia traveling C _OFF to predict again. If the predicted vehicle speed falls within the lower limit target vehicle speed Va ′ and the upper limit target vehicle speed Vb ′ in the re-prediction, the traveling on the front road is set as the accelerator-off inertia traveling C _OFF . Thereby, coasting can be performed over a longer distance, and fuel consumption can be reduced.

In particular, as shown in FIG. 3, the present invention neutralizes traveling on a front road where there is a downhill road having a descending slope capable of gravity acceleration after the uphill road while traveling in front of the top of the uphill road. If it is predicted that coasting C _NEU will occur, if it is determined that the predicted vehicle speed v1 does not fall below the lower limit target vehicle speed Va ′ before reaching the downhill road, neutral coasting C _NEU is performed from the uphill road just before the top. . As a result, the traveling on the uphill road is set to neutral coasting C _NEU until the top of the hill is reached, so the vehicle speed V is decelerated within a range that does not fall below the lower limit target vehicle speed Va ′, and the traveling on the downhill road from the top is performed. Because it is neutral coasting C _NEU , the speed will be increased. Therefore, since the travel distance by the neutral coasting C _NEU can be increased, the fuel consumption can be reduced. Further, even if the traveling on the front road FR1 is the neutral coasting traveling C _NEU , the vehicle speed V does not fall below the lower limit target vehicle speed Va ′, so that it is possible to avoid a significant increase in operation time.

  Note that the road condition of the road ahead acquired by the road condition acquisition unit M1 is not limited to the above description. For example, altitude data may be used instead of the road gradient, and in addition to the sensors and devices described above, a sensor or device that can acquire the situation of the road ahead required for automatically driving the vehicle 1 may be provided. Good.

  Further, in place of the current position acquisition device 21 which is a communication device with the satellite positioning system (GPS) of the road condition acquisition device 20, a device for storing the road condition such as a drive recorder is provided, and the stored road condition is stored. May be used.

In addition, in the above-described embodiment, the neutral inertia traveling C _NEU is used as the non-braking inertia traveling that does not apply the braking force to the traveling of the vehicle. However, the present invention is not limited to this, and for example, the clutch 4 is provided. The clutch-off inertia traveling in a disconnected state may be used. In this case, the inertia traveling control means M4 performs control for disengaging the clutch 4 instead of shifting the transmission 5 to neutral.

Furthermore, in the above-described embodiment, the accelerator-off inertia traveling C _OFF is used as the braking inertia coasting that applies the braking force to the traveling of the vehicle. However, the present invention is not limited to this. In the case of a hybrid vehicle equipped with a motor generator, regenerative traveling that regeneratively drives the motor generator to apply a braking force to the vehicle may be used.

In addition, the automatic driving method described above mainly describes the change in the gradient of the front road among road conditions. However, the present invention predicts the case where the driving on the front road is inertial driving in consideration of a curve or the like. Good. For example, if there is a curve on the front road FR6 in FIG. 5 that cannot be bent unless the vehicle speed V is decreased, the vehicle is switched from the neutral inertia traveling C _NEU to the accelerator-off inertia traveling C _OFF to reduce the curve to a speed at which it can be bent. May be.

  In the above-described automatic traveling method, it is preferable to acquire the presence / absence of a signal and the timing at which the signal is switched as a road condition in a city. For example, the fuel consumption can be further reduced by acquiring the timing at which the signal is switched and causing the vehicle 1 to automatically travel so as to avoid the stop due to the signal.

  The vehicle automatic traveling device according to the present invention can reduce the fuel consumption by increasing the traveling opportunity by inertia traveling where the fuel injection of the internal combustion engine is stopped, and the vehicle speed during the inertia traveling is an upper limit based on the target vehicle speed. Because it falls between the target vehicle speed and the lower limit target vehicle speed, it is possible to avoid delays in arrival time without greatly increasing the operation time even if the chance of coasting increases, so internal combustion engines such as diesel engines It can be used for vehicles equipped with.

1 Vehicle 2 Automatic traveling device 3 Engine (internal combustion engine)
4 Clutch 5 Transmission 10 ECU for engine (control device for internal combustion engine)
11 Power Transmission ECU (Power Transmission Control Device)
DESCRIPTION OF SYMBOLS 12 Automatic traveling control apparatus 13 Target vehicle speed setting apparatus 14 Increase / decrease value setting apparatus 20 Road condition acquisition apparatus 30 Vehicle condition acquisition apparatus 40 Braking device M1 Road condition acquisition means M2 Vehicle condition acquisition means M3 Inertial travel prediction means M4 Inertial travel control means M5 Target Vehicle speed maintenance travel control means M6 Inertia travel selection means M7 Inertia travel maximum vehicle speed maintenance means

Claims (9)

A target vehicle speed maintaining traveling control means for controlling the traveling of the vehicle equipped with the internal combustion engine to a target vehicle speed maintaining traveling for maintaining the vehicle speed at a preset target vehicle speed; and the fuel traveling of the internal combustion engine by the fuel injection of the internal combustion engine. In an automatic traveling device for a vehicle comprising inertial traveling control means for controlling inertial traveling stopped,
Based on the road situation and the vehicle situation, the road situation obtaining means for obtaining the road situation of the road ahead, the vehicle situation obtaining means for obtaining the vehicle situation including the vehicle speed, and predicting that the running of the front road is coasting A coasting traveling prediction means for determining whether or not the predicted vehicle speed in this case is lower than a lower limit target vehicle speed set in advance at a speed slower than the target vehicle speed,
When the inertia traveling prediction means is implemented and it is determined that the predicted vehicle speed does not fall below the lower limit target vehicle speed, the inertia traveling control means is implemented and the traveling on the road ahead is made inertial. An automatic traveling device for a vehicle.   When the predicted vehicle speed in the inertia traveling prediction means is lower than the lower limit target vehicle speed, or when the vehicle speed falls below the lower limit target vehicle speed during the execution of the inertia traveling control means, the target vehicle speed maintenance traveling control means is implemented. The vehicle automatic travel device according to claim 1, wherein the vehicle speed is configured to approach the target vehicle speed. The inertial running under prediction is applied to the vehicle running so that the predicted vehicle speed in the inertial running prediction means falls between the upper limit target vehicle speed and the lower limit target vehicle speed set in advance to be higher than the target vehicle speed. A coasting coasting selection means for selecting from either a braking coasting coasting that imparts a braking force or a non-braking coasting that does not impart braking force to the traveling of the vehicle,
The inertial travel when the inertial travel control means is implemented is configured to be either the braking inertial travel selected with the inertial travel selection means or the non-braking inertial travel. The automatic running device for a vehicle according to claim 1 or 2. When the coasting prediction means predicts that traveling on a road ahead with a downhill road following an uphill road based on the road condition and the vehicle situation as an inertial road, the vehicle travels until the vehicle reaches the downhill road. As a means for determining whether the predicted vehicle speed is less than the lower limit target vehicle speed,
The inertial traveling prediction means is implemented, and when it is determined that the predicted vehicle speed does not fall below the lower limit target vehicle speed until the vehicle reaches the downhill road, the inertial traveling control means is implemented from the uphill road. The vehicle automatic running device according to any one of claims 1 to 3, wherein the vehicle automatic running device is provided.   A vehicle comprising the vehicle automatic traveling device according to any one of claims 1 to 4. In the automatic traveling method of a vehicle, the traveling of the vehicle equipped with the internal combustion engine is set to a target vehicle speed maintaining traveling that maintains the vehicle speed at a preset target vehicle speed.
Based on the road conditions on the front road and the vehicle conditions including the vehicle speed, the predicted vehicle speed when the driving on the front road is predicted to be coasting with the fuel injection of the internal combustion engine stopped is slower than the target vehicle speed. A method for automatically driving a vehicle, characterized in that, when it is determined that the speed does not fall below a lower limit target vehicle speed set in advance, traveling on the front road is coasting.   7. The vehicle traveling is switched from inertia traveling to target vehicle speed maintaining traveling when the predicted vehicle speed is lower than the lower limit target vehicle speed or when the vehicle speed during inertia traveling is lower than the lower limit target vehicle speed. A method for automatically driving a vehicle according to claim 1.   A braking inertia that applies a braking force to the traveling of the vehicle during the predicted inertial traveling so that the predicted vehicle speed falls between the upper limit target vehicle speed and the lower limit target vehicle speed that are set in advance to be higher than the target vehicle speed. Either driving or non-braking coasting without applying braking force to the traveling of the vehicle is selected, and traveling on the road ahead is selected as either the selected braking inertia traveling or the unbraking inertia traveling. 8. The vehicle automatic traveling method according to claim 6 or 7, wherein the vehicle travels automatically.   Based on the road condition and the vehicle condition, when it is predicted that traveling on a road ahead having a downhill road after an uphill road is coasting, the predicted vehicle speed is set to the lower limit target before the vehicle reaches the downhill road. The method for automatically driving a vehicle according to any one of claims 6 to 8, wherein when it is determined that the vehicle speed is not reduced, coasting is started from an uphill road.

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