JP2012219986A - Travel control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a travel control device for a vehicle capable of improving fuel consumption by increasing frequency for performing inertia traveling.SOLUTION: The travel control device for the vehicle includes: an engine 1; a power connecting/disconnecting means 2 interposed between the engine 1 and a driving wheel 7; and an inertia traveling control means 130 controlling the power connecting/disconnecting means 2 to a power shut-off state to start inertia traveling when an inertia traveling start condition is achieved. The inertia traveling start condition includes a situation where a vehicle traveling passage is a downgrade or an upgrade satisfying a predetermined condition. The inertia traveling control means 130 includes: a top determination means 124 determining whether or not a top of the upgrade is located before the vehicle; and an inertia traveling start determination means 125 which estimates change in traveling speed of the vehicle in the case where the vehicle starts inertia traveling when the top determination means 124 determines that the top is located, and determines start of the inertia traveling in a predetermined condition that traveling speed V when the vehicle reaches the top by the inertia traveling becomes lower limit speed Vlow or more.

Description

  The present invention relates to a traveling control device that controls inertial traveling of a vehicle.

Conventionally, in a vehicle (such as an automobile) that travels using an engine (internal combustion engine) as a drive source, power transmission between the engine such as an automatic clutch and the drive system is performed under a predetermined condition on a downhill to improve the fuel efficiency of the vehicle. A technique is known in which coasting is performed by automatically shutting off the vehicle.
In a state where power transmission is cut off during traveling, the engine output and the rotational speed do not interlock with the wheels, and if the engine rotational speed is maintained at the idle rotational speed, fuel consumption corresponding to the idle rotational speed is made. Become.

On the other hand, in a state where power is transmitted, the engine speed is a speed corresponding to the traveling speed of the vehicle. For this reason, if the accelerator operation is not performed while the vehicle is traveling, the engine brake is applied and becomes a load for traveling the vehicle, which prevents the vehicle speed from being maintained.
Therefore, if the transmission of power between the engine and the drive system is interrupted during running to maintain the idle speed, the kinetic energy of the vehicle can be effectively used to improve fuel efficiency without loading the engine.

Thus, Patent Document 1 discloses a technique for controlling inertial running by interrupting power transmission by disconnecting a clutch.
This technology is based on the condition of the inertial travel command switch, the speed of the vehicle, the presence or absence of an accelerator or brake operation, and the acceleration of the vehicle. Thus, when the accelerator operation and the brake operation are not performed and the acceleration of the vehicle is equal to or less than a predetermined acceleration, the clutch is disengaged and inertial running is performed. Unless there is an accelerator operation and a brake operation, this coasting condition is established from the start of the downhill to the middle of the continuous uphill after the downhill, and it can be said that coasting is performed during this period.

JP 2005-226701 A

  Incidentally, among the inertial running conditions described in Patent Document 1, the condition that the vehicle speed is equal to or higher than the predetermined speed is considered so that the vehicle can be smoothly stopped by using the engine brake when the vehicle is stopped. The condition that there is no brake operation is to give priority to the driver's intention to accelerate or decelerate, and the condition that the vehicle acceleration is below the predetermined acceleration is considered to be considered so that the vehicle speed does not increase excessively. .

As described above, it is necessary to give various coasting conditions to carry out coasting in a range that does not hinder the operation of the vehicle. However, in consideration of these, the frequency of coasting is further increased. There is a desire to further improve fuel economy.
For example, as described above, the traveling path on which the vehicle travels is often followed by an uphill after a downhill, but often followed by a downhill after an uphill. If the downhill continues after the uphill, it is conceivable to carry out inertial driving within the range where there is no hindrance to the operation of the vehicle even if the vehicle does not enter the downhill near the top of the uphill.

  The present invention has been devised in view of such problems, and an object of the present invention is to provide a vehicle travel control device that can increase the frequency of coasting and improve fuel efficiency.

  In order to achieve the above object, the vehicle travel control apparatus of the present invention includes an engine, power connection / disconnection means interposed between the engine and drive wheels, and the power when the inertial travel start condition is satisfied. In the vehicle provided with inertial traveling control means for controlling the connecting / disconnecting means to the power cut-off state and starting inertial traveling, the inertial traveling start condition is that the traveling path of the vehicle is a downhill or an upward condition that satisfies a predetermined condition. It is determined that the inertial traveling control means has the top by a top determination means for determining whether or not there is a top of an uphill in front of the vehicle, and the top determination means. Then, a change in the traveling speed of the vehicle when the vehicle starts the inertia traveling is estimated, and the traveling speed when the vehicle reaches the top by the inertia traveling is equal to or higher than a lower limit speed. The predetermined It is characterized by having a coasting start determining means for determining the start of the coasting as matter.

In addition, the vehicle includes a gradient detection unit that detects a gradient of a traveling path on which the vehicle travels, and a gradient change rate detection unit that detects a change rate of the gradient. And when the rate of change is negative, it is preferable to determine that the top is present.
When the vehicle is instructed to run at a constant speed by a constant speed running command means (for example, an auto cruise switch) for automatically running the vehicle at a constant speed, and the constant speed running command means, the output of the engine is And a constant speed traveling control means for performing constant speed traveling control for operating and maintaining the traveling speed of the vehicle at the commanded instruction speed, wherein the inertial traveling control means is a constant speed traveling control means by the constant speed traveling control means. When the inertial travel start determination means determines that the inertial travel is started, the inertial travel is started, and the traveling speed of the vehicle is higher than the commanded speed by a preset speed difference. It is preferable to continue the inertial running control as long as it is within a speed band having a width defined by an upper limit speed and the lower limit speed that is lower by a preset speed difference than the command speed.

In addition, during the constant speed traveling control by the constant speed traveling control means, if the top determining means determines that there is the top, the traveling speed of the vehicle is increased from the command speed by a preset speed difference. It is preferable to have a preparation control means that raises and carries out the inertial running preparation control.
The inertial travel control means includes inertial travel end determination means for determining the end of the inertial travel control when the traveling speed of the vehicle deviates from the speed zone during the inertial travel control, and the constant speed travel When the constant speed traveling is commanded, the control means preferably operates the output of the engine by feedback control based on a deviation between the actual traveling speed of the vehicle and the commanded speed.

  Further, during the inertial traveling by the inertial traveling control means, the inertial traveling end determination means determines the end of the inertial traveling control because the traveling speed of the vehicle falls below the speed band, and the constant speed traveling is performed. In the case of returning to the above, until the traveling speed of the vehicle increases to the command speed, the output increment is larger than the output increment when the traveling speed of the vehicle is increased to the command speed during the constant speed traveling control. It is preferable to have return means for controlling the output of the engine. That is, the return means performs control by increasing the feedback gain of feedback control as compared with the normal constant speed traveling control, and outputs torque required for traveling on the current gradient traveling path at the command speed. It is preferable to switch the output of the engine so that

  According to the vehicle travel control apparatus of the present invention, when it is determined that there is a top in front of the vehicle, a change in the travel speed of the vehicle when the vehicle starts inertial traveling is estimated, and the vehicle reaches the top. Since the coasting speed is equal to or higher than the lower limit speed, the coasting start condition is set so that coasting can be started from the top of the vehicle in a range where the vehicle speed does not decrease significantly (lower limit speed or higher). Thereby, the frequency which implements coasting can be increased and a fuel consumption can be improved.

In many cases, there is a downhill next to the top of the uphill. In this case, coasting can be carried out continuously from the front of the top to the subsequent downhill, and the power connection / disconnection means can be controlled smoothly. Can be done. It is also advantageous for improving fuel consumption.
If the vehicle's running speed is within a speed range with a range defined by the upper limit speed and the lower limit speed, if the inertial running is carried out continuously from before the top to the subsequent downhill, the running speed of the vehicle is In general, it decreases from just before the top to the top, increases on the subsequent downhill and exceeds the upper limit speed, it ends coasting, but when the traveling speed of the vehicle decreases when entering the downhill, Accordingly, since the traveling speed of the vehicle at the time of entry has a margin with respect to the upper limit speed, coasting can be performed over a longer section. Thereby, a fuel consumption can be improved more.

Moreover, since the peak determination means determines that there is a peak when the gradient is positive and the change rate of the gradient is negative, it is possible to reliably determine that there is a peak before the peak.
In addition, if the vehicle travel speed is within a speed range having a range defined by the upper limit speed and the lower limit speed centered on the command speed, it is easy to allow for a high frequency or a long period if the inertial travel is continued. It is possible to carry out inertial running in the speed range and improve fuel efficiency while ensuring drivability.

  Further, if it is determined that there is a peak in front of the vehicle, the vehicle traveling speed is increased by a predetermined speed difference from the command speed to perform inertial traveling preparation control. The traveling speed when the vehicle reaches the top can be increased according to the speed difference, and the inertia traveling can be performed from the near side to the top, and the period for performing the inertia traveling can be lengthened. This is also advantageous in improving fuel consumption.

If the engine is controlled in a torque range where the fuel consumption rate (fuel consumption per unit output) is good when the vehicle running speed is increased from the command speed to a higher speed by a preset speed difference, the overall fuel economy will be achieved. Can be improved.
In addition, if the coasting is terminated when the traveling speed of the vehicle deviates from the speed range, a reduction in drivability can be avoided.

If the traveling speed of the vehicle becomes larger than the upper limit speed and coasting is terminated, for example, further acceleration on a downhill can be prevented, and safety can be ensured.
If the engine output is controlled so that the output increment is larger than the output increment during constant speed running control when the inertial running is finished below the lower limit speed and the vehicle returns to the steady running where the running is performed at the command speed. That is, if the normal feedback gain at the time of steady running is increased, it is possible to quickly shift to steady running. In this case, if the engine is controlled so that the output torque required for traveling (acceleration) to return (accelerate) the current vehicle speed to the command speed is in a torque range with a high fuel consumption rate, the overall fuel efficiency can be improved. it can.

1 is a diagram illustrating an overall configuration of a vehicle according to an embodiment of the present invention. It is a figure explaining the fuel consumption rate concerning one Embodiment of this invention. It is a flowchart which shows determination of the start or completion | finish of the traveling control of the vehicle concerning one Embodiment of this invention. It is a flowchart which shows the whole traveling control of the vehicle concerning one Embodiment of this invention. It is a flowchart which shows the routine concerning the top determination concerning one Embodiment of this invention. It is a flowchart which shows the routine concerning the peak front inertia running condition (predetermined condition) concerning one Embodiment of this invention. It is a flowchart which shows the preparation control which is a routine of the traveling control of the vehicle concerning one Embodiment of this invention. It is a flowchart which shows the normal auto cruise traveling control which is a routine of the traveling control of the vehicle concerning one Embodiment of this invention. It is a flowchart which shows the return control which is a routine of the traveling control of the vehicle concerning one Embodiment of this invention. It is a flowchart which shows the inertial traveling control which is a routine of the traveling control of the vehicle concerning one Embodiment of this invention. It is a figure which shows a vehicle speed, the connection / disconnection state of a clutch, an engine speed, and the output torque of an engine according to the traveling path of the vehicle concerning one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[One Embodiment]
FIGS. 1 to 11 illustrate a vehicle travel control apparatus according to an embodiment of the present invention. FIG. 1 is a diagram illustrating the overall configuration, and FIG. 2 is a diagram illustrating a fuel consumption rate. 3 to 10 are flow charts showing vehicle travel control, FIGS. 5 to 10 are flow charts showing routines thereof, and FIG. 11 shows vehicle speed, clutch state, engine rotation according to the vehicle travel path. It is a figure which shows a number and the output torque of an engine. 3 shows determination of start or end of vehicle travel control, FIG. 4 shows overall vehicle travel control, FIG. 5 shows top determination, which is the routine of FIG. 4, and FIG. 6 shows FIG. FIG. 7 shows preparation control as a routine of FIG. 4, FIG. 8 shows normal auto-cruise running control as a routine of FIG. 4, and FIG. 9 shows the routine of FIG. FIG. 10 shows inertial running control as a routine of FIG. 4.

〔overall structure〕
First, the configuration of a vehicle to which the travel control device according to the present embodiment is applied will be described. The vehicle according to the present embodiment is an automobile such as a truck or a bus.
As shown in FIG. 1, the vehicle has an engine (internal combustion engine) 1, a clutch (power connection / disconnection means) 2, a transmission 3, a propeller shaft 4, a differential gear 5 and a drive as a drive system for rotationally driving the drive wheels 7. A shaft 6 is provided.

The engine 1 is an internal combustion engine that uses gasoline or light oil as fuel, for example, and its output rotation is output to an output shaft (not shown).
The clutch 2 is interposed between the engine 1 and the transmission 3. Although not shown in detail, the clutch 2 includes an input side plate coupled to the output shaft of the engine 1 and an output side plate coupled to the input shaft of the transmission 3. And an interrupted state in which both plates are separated from each other by an actuator (not shown). If the clutch 2 is disconnected during traveling, the engine 1 is disconnected from the drive system of the vehicle and power is not transmitted. If the clutch 2 is connected, the engine 1 is added to the drive system of the vehicle and power is transmitted.

  Therefore, in the state where the clutch 2 is connected (completely connected), if the speed of the transmission 3 is constant, the rotational speed of the engine 1 (also referred to as Ne or engine rotational speed) is the rotational speed corresponding to the traveling speed of the vehicle. It becomes. For this reason, during normal driving (during driving at medium speed or higher), the engine brake operates if there is no accelerator operation. Further, in the state where the clutch 2 is disengaged, the engine 1 is disconnected from the power system and no drive output is required. Therefore, the engine speed can be set to the idle speed (idle) and coasting can be performed.

The above-mentioned actuator (not shown) is attached to the clutch 2, and the clutch 2 is automatically disconnected and connected (hereinafter also referred to as “disconnected”) by controlling the operation of the actuator by a vehicle ECU 100 described later. That is, the clutch 2 is an automatic clutch that is connected / disconnected by the actuator.
The input shaft of the transmission 3 is connected to the clutch 2, and the output shaft of the transmission 3 is driven through a power transmission system including a propeller shaft 4, a differential gear 5, a drive shaft 6, etc. Left and right rear wheels 7).

[Control system configuration]
The engine 1, the clutch 2 and the transmission 3 are controlled by electronic control by the vehicle ECU 100 based on information from various sensors related to the vehicle.
The vehicle ECU 100 is a computer comprising a CPU, ROM, RAM, input / output circuit, etc., and calculates control command values for the engine 1, clutch 2 and transmission 3 based on information from various sensors. The engine 1, the clutch 2 and the transmission 3 are controlled based on the control command value.

  The sensors include a gradient sensor (gradient detection means) 10, an APS (accelerator position sensor) 20, a foot brake SW (foot brake switch) 30, a vehicle speed sensor 40, an auto cruise SW (auto cruise switch, constant speed travel). Command means) 50 and inertial travel permission SW (inertia travel permission switch, inertial travel permission means) 52. First, these sensors will be described.

The gradient sensor 10 detects the gradient of the traveling path on which the vehicle is traveling at the present time as the gradient value θ, and here, a gradient sensor is used. In this case, the gradient value θ can be detected with higher accuracy by estimating the inclination of the vehicle with respect to the road surface (front up, back up, etc.) and correcting the value detected by the inclination sensor.
If the gradient value θ detected by the gradient sensor 10 is positive, it indicates that the traveling road is an uphill, and if the gradient value θ is negative, it indicates that the traveling road is a downhill.

In place of the gradient sensor 10, a height sensor, an acceleration sensor, a GPS, a gyro sensor, or a combination thereof may be used as long as the gradient value θ of the travel path can be detected.
For example, when a height sensor and an acceleration sensor are combined, the vehicle is tilted in the front-rear direction with respect to the travel path based on the vehicle heights of the front and rear of the vehicle detected by height sensors provided at the front and rear of the vehicle. And the gradient value θ can be estimated by referring to a map in which the gradient value of the travel path is determined. Also in this case, if the gradient value estimated by the acceleration detected by the acceleration sensor is corrected, the gradient value θ can be detected with higher accuracy.

  Further, if GPS is used, the gradient value θ can be detected based on the position (latitude, longitude, altitude) of the vehicle acquired every moment by GPS. Furthermore, if GPS is combined with a gyro sensor, the sampling rate of vehicle position information detected by GPS can be further improved, and the gradient value θ can be detected with higher accuracy. Also, for example, even in a situation where GPS signals cannot be received in a tunnel or the like, a change in the traveling direction (turning direction) of the vehicle is detected by a gyro sensor, and position information such as altitude information acquired by the GPS most recently is obtained. If the vehicle is complemented by a change in the traveling direction of the vehicle detected by the gyro sensor, the gradient value θ can be calculated.

The APS 20 detects the accelerator operation amount operated by the driver. In the present embodiment, the driver's intention to accelerate is detected by the APS 20. That is, if the detected accelerator operation amount is less than or equal to a minute threshold value, it is assumed that the accelerator operation is not performed and the driver does not intend to accelerate.
The foot brake SW30 detects the presence or absence of a foot brake operation operated by the driver. If there is a foot brake operation, the foot brake SW30 is turned on and the brake lamp is lit. If the foot brake operation is not performed, the foot brake SW30 is turned off. Turns off. Here, if the signal from the foot brake SW30 is ON, it is assumed that the brake is being operated and the driver intends to decelerate. If the signal from the foot brake SW30 is OFF, the brake is not being operated. It is assumed that the driver does not intend to slow down.

The vehicle speed sensor 40 detects the vehicle speed. As the vehicle speed sensor 40, for example, a wheel speed sensor that detects the rotational speed of each driven wheel can be applied. In the case of this wheel speed sensor, the vehicle speed is calculated by calculating the average speed of the detected rotational speed of each driven wheel. Can be calculated.
The auto-cruise SW 50 is a switch that is selected and operated by the driver. When the auto-cruise SW 50 is turned on, the auto-cruise mode is permitted, and when the auto-cruise SW 50 is turned off, the auto-cruise mode is prohibited. The auto cruise mode will be described later.

Even when the auto cruise SW 50 is in the ON state, if the driver's intention to accelerate or decelerate is found, that is, if the accelerator operation amount is detected by the APS 20, or if the brake operation is detected by the foot brake SW 30, It is switched to the OFF state (auto cruise mode prohibited state).
When the auto cruise SW 50 is turned on, the vehicle ECU 100 described later sets the traveling speed (hereinafter also referred to as a vehicle speed) V of the vehicle detected by the vehicle speed sensor 40 at the time of this operation as the command speed Vst.

  The inertial travel permission SW 52 is a switch that is selected and operated by the driver. On the precondition that the auto-cruise SW50 is turned on, if the inertial travel permission SW52 is turned on, inertial travel is permitted, and OFF If operated, coasting is prohibited. If the auto cruise SW 50 is in the OFF state, the inertial travel permission SW 52 cannot be turned on.

Each of these SWs 50 and 52 may be provided with a separately provided switch, or one of auto cruise mode, coasting mode, traveling in auto cruise mode, and coasting (control traveling) prohibition mode. A single switch that can be selected may be applied.
In addition, the vehicle ECU 100 includes a control travel start determination unit 105, a gradient change rate calculation unit (gradient change rate detection unit) 110, an auto cruise mode control unit 120, and an inertia travel control unit (inertia travel control unit) 130. Have and control them.

The controlled travel start determination unit 105 determines the start and end of the controlled travel.
Control start conditions include a condition for starting travel in the auto cruise mode and a condition for starting coasting under this condition. The coasting start determination unit 105 determines each of these start conditions.
In addition to detecting that the accelerator operation is not performed by the APS 20 and that the foot brake operation is not performed by the foot brake SW30, the running start condition in the auto cruise mode is that the auto cruise SW 50 is in the ON state. That is. That is, if the driver does not intend to accelerate and decelerate and the driver permits the auto-cruise mode, the driving start condition for the auto-cruise mode is satisfied.

The inertia travel start condition is that the inertia travel permission SW 52 is in an ON state in addition to the travel start condition in the auto cruise mode. That is, the coasting start condition is satisfied after the traveling start condition in the auto-cruise mode is satisfied, so the coasting is performed under the auto-cruise mode.
The controlled travel end conditions include a condition to end the travel in the auto cruise mode and a condition to end the inertial travel, and the inertial travel start determination unit 105 determines each of these end conditions.

  The termination condition of the auto cruise mode is that the accelerator operation is detected by the APS 20, the foot brake operation is detected by the foot brake SW30, or the auto cruise SW50 is turned off. . That is, if the driver intends to accelerate or decelerate, or if the driver does not permit the auto-cruise mode, the travel end condition for the auto-cruise mode is satisfied.

The inertial travel end condition corresponds to any one of the inertial travel permission SW 52 being turned OFF in addition to the travel end condition in the auto cruise mode. That is, coasting is terminated even when the traveling end condition in the auto-cruise mode is satisfied.
The controlled travel start determination unit 105 periodically determines the start and end conditions of the controlled travel, whether during controlled travel or during normal travel.

When vehicle inertial start determination unit 105 determines that each start condition is satisfied, vehicle ECU 100 causes each control unit 120, 130 to perform the travel control, and inertial travel start determination unit 105 satisfies each end condition. When it is determined to do so, the traveling control by the control units 120 and 130 is terminated.
The gradient change rate calculation unit 110 calculates a time change rate (gradient change rate) dθ / dt (hereinafter also simply referred to as dθ) of the gradient value θ detected by the gradient sensor 10. If the slope change rate dθ is negative on the uphill, the slope value θ gradually becomes a gentle road, and if the slope change rate dθ is positive on the uphill, the slope value θ gradually increases. A steep downward projecting road. Instead of the gradient change rate calculation unit 110, a sensor that directly detects the gradient change rate dθ may be used.

The auto-cruise mode control unit 120 controls each run during the auto-cruise mode, and includes a control unit that controls each run and various determination units.
Each of the above-described control units includes a normal auto cruise travel control unit (constant speed travel control unit) 121, a preparation control unit (preparation control unit) 122, and a return control unit (return control unit) 123. In addition, the determination unit includes a top determination unit (top determination unit) 124 and an inertia travel start determination unit (inertia travel start determination unit) 125.

During the auto cruise mode, normal auto cruise travel, return travel, and preparation travel are performed. If the inertial travel permission SW 52 is in the OFF state, only normal aud cruise travel is performed. The return travel and the preparation travel will be described later.
The normal auto cruise travel control unit 121 controls normal auto cruise travel that travels while maintaining the vehicle speed V at the command speed Vst.

  In this normal auto cruise traveling control, the fuel injection change amount Δf1 is adjusted according to the amount obtained by multiplying the speed difference (Vst−V) between the command speed Vst and the vehicle speed V by the feedback gain G1, and the vehicle speed V is set to the command speed Vst. The fuel injection amount is adjusted so as to converge. That is, the output of the engine 1 is operated by feedback control based on the deviation between the vehicle speed V and the command speed Vst by normal auto cruise traveling control.

The inertial travel control unit (inertia travel control means) 130 controls the travel in the inertial travel mode (inertia travel) and has an inertial travel end determination unit (inertia travel end determination means) 131.
The inertia traveling is a coasting operation in which the clutch 2 is disengaged and the engine speed is set to the idle speed.
This inertial traveling is performed when the inertial traveling start determination unit 125 described later determines that the inertial traveling start condition is satisfied. The coasting start conditions include an uphill travel condition (pre-top coastal travel condition) and a downhill travel condition (downhill coastal travel condition). Are determined according to the gradient value θ of the traveling road.

During this inertia traveling, the engine 1 is disconnected from the power transmission system, and the engine 1 consumes fuel according to the operation at the idling speed in a state where there is no driving load. That is, by inertial running, fuel efficiency can be improved as compared to running at an engine speed corresponding to the vehicle speed V with the clutch 2 connected.
The inertia travel end determination unit 131 determines the end condition of the inertia travel. The end condition is that the vehicle speed V is larger than the upper limit speed Vupp or smaller than the lower limit speed Vlow (outside the speed range). This determination is performed when the control travel start condition by the control travel start determination unit 105 is satisfied, and can be said to be a determination of switching from inertial travel during control travel to travel in the auto cruise mode.

The inertial traveling control unit 130 continues the inertial traveling control as long as the inertial traveling end determination unit 131 determines that the inertial traveling condition is not satisfied.
The speeds Vupp and Vlow are set by the vehicle ECU 100 when the command speed Vst is set, that is, when the auto cruise SW 50 is turned on.
The upper limit speed Vupp is a speed that is higher than the command speed Vst by a preset speed difference, and the lower limit speed Vlow is a speed that is lower than the command speed Vst by a preset speed difference. The preset speed difference between these speeds Vupp and Vlow may be set quantitatively or may be set as a ratio to the command speed Vst.

When inertial travel end determination unit 131 determines that the inertial travel end condition is satisfied, vehicle ECU 100 connects clutch 2. Note that switching of the clutch 2 from the disengaged state to the connected state is performed by the vehicle ECU 100 with appropriate lamp control so that the clutch 2 is smoothly connected.
When the inertial running is finished, if the vehicle speed V is higher than the upper limit speed Vupp, the clutch 2 is connected and an appropriate engine brake is applied, and if necessary, the service brake is operated to converge the vehicle speed V to the command speed Vst. Let Here, the service brake is operated by operating the brake actuator without the driver's foot brake operation. Further, if the vehicle speed V is smaller than the lower limit speed Vlow, the return running is subsequently performed.

The return travel is performed by the return control unit 123 and accelerates the vehicle speed V to return to the command speed Vst. That is, the return control is a transient control that is performed when switching from inertial traveling control to normal auto cruise traveling control.
In this return control, the fuel injection change amount Δf2 is adjusted according to the amount obtained by multiplying the speed difference (deviation) between the command speed Vst and the vehicle speed V by the feedback gain G2. As a result, the vehicle speed V is accelerated to the command speed Vst and returned. The gain G2 is set to be larger than the gain G1 during normal auto cruise control. In other words, the feedback gain G2 of the feedback control is set to be larger than the gain G1 at the time of normal auto cruise control (normal time) and control is performed. Is. Therefore, the fuel injection change amount Δf2 per control cycle during the return control is larger than the fuel injection change amount Δf1 during the normal auto cruise traveling control.

As described above, for example, if the fuel injection amount is increased, the output torque of the engine 1 increases, and then the vehicle speed V increases. Here, the fuel consumption rate corresponding to the output torque of the engine 1 (hereinafter also simply referred to as output torque) and the engine speed (Ne) corresponding to the vehicle speed V will be described with reference to FIG.
FIG. 2 shows the fuel consumption rate with the output torque on the vertical axis and the engine speed (Ne) on the horizontal axis.

The maximum value of the output torque at an arbitrary engine speed is the torque output by the engine 1 when the engine 1 is operated at full load. The output torque of the full load has a characteristic of gradually increasing and then decreasing as the engine speed increases. This full load output torque curve is indicated by a thick line in FIG.
Also, lines a, b, c, and d in FIG. 2 indicate equal fuel consumption rate lines that are equal in fuel consumption rate (fuel consumption per unit output). These equal fuel consumption rate lines a, b, c, and d have a small fuel consumption per unit output from line d to line a and good fuel efficiency. Therefore, in FIG. 2, the fuel consumption per unit output is the smallest in the region (best fuel consumption region) surrounded by the equal fuel consumption rate line a and the full load output torque curve. This best fuel efficiency region is indicated by the shaded region in FIG.

  For example, changes in engine speed and output torque when accelerating from an arbitrary vehicle speed V1 to a vehicle speed V2 that is higher than the vehicle speed V1 by a constant speed difference will be described. In this case, the gear stage of the transmission 3 is constant, the engine speed corresponding to the vehicle speed V1 is r1, and the engine speed corresponding to the vehicle speed V2 is r2. Further, as the vehicle speeds V1 and V2, a lower limit speed Vlow and a command speed Vst, a command speed Vst, an upper limit speed Vupp, and the like can be applied.

In the state s1, it is assumed that the vehicle is traveling while maintaining the vehicle speed V1 at the engine speed r1 and the torque N1.
The state s2 is a state in which the vehicle speed V1 starts to be increased (accelerated) to the vehicle speed V2, and the output torque is increased and acceleration is started with the torque N3 in the best fuel efficiency region. In this case, the engine speed r1 is equal and the vehicle speed V1 is equal in the constant speed running state s1 and the acceleration start state s2.

However, the ratio of the output torque N3 in the state s2 is larger than the ratio of the output torque N1 in the state s1 to the full load output torque at the engine speed r1. That is, the torque efficiency is better in the state s2 than in the state s1.
The state s3 is a state in which the increase (acceleration) from the vehicle speed V1 to the vehicle speed V2 is completed. That is, acceleration is performed from state s2 to state s3.

In this state s2 to s3, the output torque N3 is maintained, and acceleration is performed within the best fuel efficiency region. In the state s3, the vehicle speed V2 and the engine speed r2.
In the state s4, the vehicle travels while maintaining the vehicle speed V2 at the engine speed r2 and the torque N2.
The dashed-dotted line shown in FIG. 2 shows the case where acceleration from the vehicle speed V1 to the vehicle speed V2 is performed with a relatively small increase amount of the output torque. In this case, it takes a relatively long time to accelerate from the vehicle speed V1 to the vehicle speed V2, and fuel is consumed near the equal fuel consumption rate line b without entering the best fuel consumption region. The fuel consumption when the increase amount of the output torque is made relatively small will be described later with reference to FIGS. 11 (d) and 11 (e). 11 (d) and 11 (e) correspond to the case indicated by the alternate long and short dash line in FIG.

Therefore, when accelerating from the vehicle speed V1 to the vehicle speed V2 that is higher than the vehicle speed V1 by a constant speed difference, for example, the fuel injection change amount Δf2 is adjusted so that the output torque enters the best fuel efficiency region, thereby improving the torque efficiency. Can do. Thereby, the fuel consumption of the whole traveling improves.
In traveling during return control, the output torque has a margin up to the best fuel efficiency region even when traveling on an uphill when the vehicle speed V during inertial traveling is less than the commanded speed Vst. When the torque increase amount corresponding to the change amount Δf2 is increased, the fuel consumption is improved by entering or approaching the best fuel consumption range. Further, when the engine speed is the same, the engine friction does not change even if the torque is increased. Therefore, when the torque is increased, the output of the engine 1 with respect to the fuel injection amount is increased, so that the fuel consumption can be improved.

The return control means 123 ends the return running when the vehicle speed V reaches the command speed Vst. Then, normal auto-cruise traveling or preparation traveling is performed.
The preparation travel is performed by the preparation control unit 122 and increases the vehicle speed V to the upper limit speed Vupp and prepares for inertia travel. That is, the preparation control is transient control at the time of switching from normal auto cruise traveling control or return control to inertial traveling control.

This preparation control is performed on the assumption that the gradient value θ is smaller than a preset gradient threshold θth. This threshold gradient θth is a threshold set experimentally and empirically in advance that fuel efficiency deteriorates when the vehicle is accelerated on a traveling road having a gradient value higher than that on an uphill.
The start condition of the preparation control is that there is a top P in front of the vehicle. The determination that there is a front apex P is performed by the apex determination unit 124.

The summit determination unit 124 determines whether or not the peak P between the uphill and the downhill is in front of the vehicle. Specifically, when the gradient value θ of the traveling road detected by the gradient sensor 10 is positive and the gradient change rate dθ calculated by the gradient change rate calculation unit 110 is negative, the vehicle reaches the top in front of the vehicle. It is determined that there is P.
As the gradient value θ or gradient change rate dθ in the peak determination, an average (moving average) of some recent data can be adopted, and a value obtained through an appropriate low-pass filter can be adopted. According to this, the peak determination unit 124 performs the determination based on the smoothed values θ and dθ from which the pulsation component has been removed, and therefore can perform stable peak determination.

When an uphill is followed by a downhill, the uphill traveling road before the summit P generally has a positive gradient value θ and a negative gradient change rate dθ. Using this, it is determined whether or not there is a top P in front of the vehicle.
When the preparation control is started, the vehicle speed V is increased to the upper limit speed Vupp. When the vehicle speed V reaches the upper limit speed Vupp, the vehicle speed V is controlled so as to maintain the upper limit speed Vupp. The vehicle speed V is increased to the upper limit speed Vupp by adjusting the fuel injection change amount Δf2 corresponding to the amount obtained by multiplying the speed difference (deviation) between the upper limit speed Vupp and the vehicle speed V by the feedback gain G2. Thereby, the vehicle speed V is raised to the upper limit speed Vst. The gain G2 is set to be larger than the gain G1 during normal auto cruise control. In other words, the control is performed by increasing the feedback gain G2 of feedback control to be greater than the gain G1 during normal auto cruise control.

  The increase of the vehicle speed V to the upper limit speed Vupp is performed so that the efficiency of the output torque of the engine 1 is improved. In other words, when the assumed vehicle speed V during inertial traveling is in the speed range around the command speed Vst, even when traveling uphill, the torque has a margin up to the best fuel consumption region, so if the torque increase amount is increased, Enter or approach the best fuel economy area and improve fuel economy. Further, when the engine speed is the same, the engine friction does not change even if the torque is increased. Therefore, when the torque is increased, the output of the engine 1 with respect to the fuel injection amount is increased, so that the fuel consumption can be improved.

When the vehicle speed V reaches the upper limit speed Vupp, the preparation control unit 123 maintains the vehicle speed V at the upper limit speed Vupp. This maintenance control is the same as the normal auto cruise traveling control.
The end condition of the preparation control is that the top-front inertia running condition (predetermined condition) is satisfied. This pre-top inertia travel condition is determined by the inertia travel start determination unit 125. When the preparation control end condition is satisfied, inertial traveling control is performed.

Hereinafter, the pre-top inertia running conditions determined by the inertia running start determining unit 125 will be described. This coastal inertial traveling condition is a coasting start condition when the traveling path is uphill.
The pre-top inertia traveling condition is that the vehicle speed Vp when reaching the top P by inertia traveling is equal to or higher than the lower limit speed Vlow. Specifically, assuming that the gradient change rate dθ from the current vehicle to the peak P is constant, a point where the gradient value θ is 0 based on the current gradient value θ and the gradient change rate dθ is the peak P. The vehicle speed Vp when reaching the top P by inertia traveling is estimated and calculated on condition that the vehicle speed Vp is equal to or higher than the lower limit speed Vlow.

  This summit P is estimated and calculated as a flat point between the uphill and the downhill or a point where the gradient value θ is zero. A vehicle speed Vp at the summit P is calculated. That is, the pre-top inertial travel start condition is that the top P is estimated and calculated on the travel path where the slope value θ gradually decreases near the top P, and the vehicle speed Vp at the top P point when coasting is started at the present time is The vehicle speed Vp at the calculated summit P is established if it is equal to or higher than the lower limit speed Vlow.

  The vehicle ECU 100 has a map in which the relationship between the shape of the route (traveling road), the vehicle speed V, and the vehicle weight W is set in advance. Using this map, the inertial travel start determination unit 125 can calculate the vehicle speed Vp at the top P. The vehicle speed Vp at the top P is calculated by calculating the shape of the route (traveling road) from the current vehicle position to the top P based on the gradient value θ and the gradient change rate dθ, and based on the shape of the route, the vehicle speed V and The amount of decrease in the vehicle speed V according to the vehicle weight W can be read out from the map and estimated and calculated.

In addition, the inertial travel start determination unit 125 determines that the inertial travel start determination condition is satisfied even when the travel path is not an uphill, for example, when entering a downward slope from a flat road. That is, when the gradient value θ changes from positive to negative gradient value θ including 0, the coasting start determination condition is satisfied.
If the inertial travel start determining unit 125 determines that the inertial travel start condition is satisfied, the vehicle ECU 100 disconnects the clutch 2 and the inertial travel control unit 130 controls the inertial travel.

[Action / Effect]
Since the vehicle travel control apparatus according to the embodiment of the present invention is configured as described above, for example, vehicle controlled travel is performed as follows.
A flow for determining whether or not to start the controlled travel will be described with reference to FIG. This determination is performed by the controlled travel start determination unit 105, and is periodically performed, for example, every several tens of milliseconds.

First, in step S1, it is determined whether or not the foot brake SW30 is OFF. If the foot brake SW30 is OFF, the process proceeds to step S2, and if it is ON, the process proceeds to step S9.
In step S2, it is determined whether the APS 20 is OFF, that is, whether an accelerator operation is not performed. If APS20 is OFF, it will transfer to step S3, and if it is ON, it will transfer to step S9.

In step S3, it is determined whether or not the auto cruise SW 50 is in an ON state. If the auto cruise SW 50 is in the ON state, the process proceeds to step S4, and if it is in the OFF state, the process proceeds to step S9.
In step S4, the flag F1 is set to 0. Then, the process proceeds to step S5.
The flag F1 is set to 0 if the vehicle is in controlled travel and is in the auto cruise mode with the clutch 2 connected, and is set to 1 if the vehicle is in the inertial travel mode with the clutch 2 disconnected.

In step S5, the flag F2 is set to 0. Then, the process proceeds to step S6.
The flag F2 is a flag in the auto-cruise mode (F1 = 0), and is set to 0 when normal auto-cruise control is executed, and is set to 1 when return control is executed, and preparation control is executed. Set to 2 when done.
In step S6, it is determined whether the inertial travel permission SW 52 is in an ON state. If the inertial travel permission SW 52 is in the ON state, the process proceeds to step S7. If the inertial travel permission SW 52 is in the OFF state, the process proceeds to a normal auto cruise travel control routine described later.

In step S7, it is determined that the control travel start condition is satisfied. That is, it is determined by the control travel start unit 105 that the control travel start condition has been established, and the vehicle ECU 100 causes the auto cruise mode control unit 120 to perform travel control. Then return.
In step S9, it is determined that the controlled travel end condition is satisfied. In other words, if the foot brake SW30 is ON, the APS 20 is ON, or the auto cruise SW 50 is OFF, the control travel end condition is satisfied. When it is determined that the controlled travel end condition is satisfied, the vehicle ECU 100 interrupts the controlled travel and normal driving by the driver is performed. Then move to the end.

When the above-described controlled travel start condition is satisfied, vehicle travel control as shown in FIG. 4 is performed by vehicle ECU 100. This control flow is performed periodically, for example, every several tens of ms.
First, in step S100, information on various sensors is acquired. For example, the gradient value θ from the gradient sensor 10, the current vehicle speed V from the vehicle speed sensor 40, and other information are acquired. Then, the process proceeds to step S110.

In step S110, it is determined whether or not the flag F1 is 0. If the flag F1 is 0, the process proceeds to step S120, and if the flag F1 is not 0 (if 1), the process proceeds to step S300.
In step S120, it is determined whether or not the flag F2 is 0. If the flag F2 is 0, the process proceeds to the top determination routine. If the flag F2 is not 0, the process proceeds to step S200.

In the top determination routine, it is determined whether or not the top P is in front of the vehicle. This determination is performed by the peak determination unit 124, and details will be described with reference to FIG.
When the determination of whether or not the top P is in front of the vehicle starts, in step S130, it is determined whether or not the gradient value θ detected by the gradient sensor 10 is positive (uphill). If the gradient value θ is positive, the process proceeds to step S132, and if the gradient value θ is negative, the process proceeds to step S138.

In step S132, it is determined whether the gradient change rate dθ calculated by the gradient change rate calculation unit 110 is negative (whether the upward gradient value θ is gradually decreasing on the travel path). If the gradient change rate dθ is negative, the process proceeds to step S134, and if the gradient change rate dθ is positive, the process proceeds to step S138.
In step S134, it is determined that there is a summit P in front of the vehicle.

That is, in step S130 and step S132, when the gradient value θ is positive and the gradient change rate dθ is negative, the peak determination unit 124 determines that the peak P is in front of the vehicle.
In step S138, it is determined that there is no top P in front of the vehicle.
That is, in step S130 and step S132, when the gradient value θ is negative or the gradient change rate dθ is positive, the peak determination unit 124 determines that there is no peak P ahead of the vehicle.

If it is determined in this peak determination routine that there is a peak, the process proceeds to step S140 in FIG. 4, and if it is determined that there is no peak, the process proceeds to step S20.
In step S140, it is determined whether or not the gradient value θ is smaller than the threshold gradient θth. When the gradient value θ is smaller than the threshold gradient θth, the process proceeds to step S150, and when the gradient value θ is equal to or greater than the threshold gradient θth, the process proceeds to step S20. In step S140, a precondition for performing the preparation control is determined.

In other words, if it is determined in the summit determination routine that the summit P is not in front of the vehicle, or if the gradient value θ is greater than or equal to the threshold gradient θth in step S140, the process proceeds to step S20.
In step S20, the control travel start determination unit 105 determines whether a downhill coasting travel condition is satisfied. The downhill coasting condition is that the gradient value θ changes from positive to negative gradient value θ including zero. If it is determined that the downhill coasting condition is satisfied, the process proceeds to step S500. When it is determined that the downhill coasting condition is not satisfied, the routine proceeds to a routine of normal auto cruise traveling control.

In step S150, the flag F2 is set to 2. Then, the routine proceeds to a summit front inertia running start condition determination routine.
In the pre-top inertial travel start condition determination routine, the inertial travel start determination unit 125 determines whether or not the pre-top inertial travel condition is satisfied. Details will be described with reference to FIG.
When the head-front inertia running start condition determination routine is started, the gradient value θ detected by the gradient sensor 10, the gradient change rate dθ calculated by the gradient change rate calculation unit 110, and the vehicle speed detected by the vehicle speed sensor 40 in step S 160. Based on V, the point of the summit P is calculated. The summit P is calculated as a point where the gradient value θ becomes 0 based on the current gradient value θ and the gradient change rate dθ when the gradient change rate dθ from the current vehicle to the summit P is constant. Then, the process proceeds to step S162.

In step S162, based on the gradient value θ, the gradient change rate dθ, and the summit P calculated in step S160, the vehicle speed Vp at the summit P when the inertial running is started and the summit P is reached by inertial running is estimated. calculate. Then, control goes to a step S164.
In step S164, it is determined whether or not the vehicle speed Vp at the top P is equal to or higher than the lower limit speed Vlow.

If the vehicle speed Vp is equal to or higher than the lower limit speed Vlow, the routine proceeds to step S500, where the flag F1 is set to 1, and the routine proceeds to the inertial running routine. If the vehicle speed Vp is smaller than the lower limit speed Vlow, the process proceeds to the preparation control routine. The preparation control routine will be described later.
Step S200 is a step that is shifted to when it is determined that the flag F2 is not 0, and it is determined whether or not the flag F2 is 1. If the flag F2 is 1, the process proceeds to step S220, and if the flag F2 is not 1 (if 2), the process proceeds to the top pre-inertia travel start condition determination routine.

In step S220, it is determined whether the return control is completed. That is, it is determined whether or not the vehicle speed V has reached the command speed Vst. If the vehicle speed V has reached the command speed Vst, the process proceeds to step S240, and if not, the process proceeds to a return control routine to continue the return control. The return control routine will be described later.
In step S240, the flag F2 is set to 0. Then, the routine proceeds to a normal auto cruise control routine. The normal auto cruise traveling control will be described later.

Step S300 is a step that is shifted to when it is determined that the flag F1 is not 0, and determines whether or not the vehicle speed V is lower than the lower limit speed Vlow. If the vehicle speed V is lower than the lower limit speed Vlow, the process proceeds to step S320. If the vehicle speed V is equal to or higher than the lower limit speed Vlow, the process proceeds to step S400.
In step S320, the flag F1 is set to 0. Further, if the clutch 2 is in the disconnected state, the connected state is set. The transition from the disconnected state to the connected state of the clutch 2 is appropriately controlled by the vehicle ECU 100. Then, the process proceeds to step S340.

In step S340, the flag F2 is set to 1. Then, the process proceeds to a return control routine. The return control routine will be described later.
Step S400 is a step that is shifted when it is determined that the vehicle speed V is equal to or higher than the lower limit speed Vlow, and it is determined whether or not the vehicle speed V is higher than the upper limit speed Vupp. If the vehicle speed V is greater than the upper limit speed Vupp, the routine proceeds to step S420, and if the vehicle speed V is equal to or lower than the upper limit speed Vupp, the routine proceeds to a coasting control routine. The inertial running control routine will be described later.

In step S420, the flag F1 is set to 0. Further, if the clutch 2 is in the disconnected state, the connected state is set. The transition from the disconnected state to the connected state of the clutch 2 is appropriately controlled by the vehicle ECU 100. Then, the process proceeds to step S440.
In step S440, the flag F2 is set to 0. Then, the routine proceeds to a normal auto cruise control routine. The normal auto cruise control routine will be described later.

Hereinafter, preparation control, normal auto cruise traveling control, return control, and inertia traveling control, which are routines during traveling control, will be described with reference to FIGS. 7 to 10.
First, the preparation control will be described with reference to FIG. This preparation control is performed by the preparation control unit 122 and is a control for increasing the vehicle speed V to the upper limit speed Vupp and preparing for inertial running.

In the preparation control, first, in step S170, it is determined whether or not the vehicle speed V is smaller than the upper limit speed Vupp. If it is determined that the speed is lower than the upper limit speed Vupp, the process proceeds to step S172, and if not smaller, the process proceeds to step S180.
In step S172, the fuel injection change amount Δf2 is adjusted according to the amount obtained by multiplying the speed difference (Vupp−V) between the upper limit speed Vupp and the vehicle speed V by the feedback gain G2. Then, control goes to a step S174.

In step S174, the fuel injection change amount Δf2 is added to the current fuel injection amount f, and the vehicle ECU 100 increases the output torque of the engine 1 with the adjusted fuel injection amount (f + Δf2). Then return.
In step S180, it is determined whether or not the vehicle speed V has reached the upper limit speed Vupp. If the vehicle speed V is the upper limit speed Vupp, the process proceeds to step S182. If the vehicle speed V is not the upper limit speed Vupp, the process proceeds to step S190.

In step S182, the fuel injection amount is adjusted so that the current fuel injection amount f is maintained and the vehicle speed V is maintained at the upper limit speed Vupp. Then return.
In step S190, the fuel injection change amount Δf1 is adjusted according to the amount obtained by multiplying the speed difference (Vupp−V) between the upper limit speed Vupp and the vehicle speed V by the feedback gain G1. Then, control goes to a step S192.

Here, the feedback gain G1 in step S190 is set smaller than the feedback gain G2 in step S172. Therefore, the fuel injection change amount Δf1 is also smaller than the fuel injection change amount Δf2.
In step S192, the fuel injection change amount Δf1 is added to or subtracted from the current fuel injection amount f, and the vehicle ECU 100 sets the output torque of the engine 1 to the output torque of the engine 1 with the adjusted fuel injection amount (f ± Δf1). Adjust to converge. Then return.

Next, normal auto cruise traveling control will be described with reference to FIG. This control is performed by the normal auto cruise traveling control unit 121 and maintains the vehicle speed V at the command speed Vst.
In the normal auto cruise traveling control, first, in step S260, it is determined whether or not the vehicle speed V is the command speed Vst. If the vehicle speed V is the command speed Vst, the process proceeds to step S262. If the vehicle speed V is not the command speed Vst, the process proceeds to step S280.

In step S262, the current fuel injection amount f is maintained, and the fuel injection amount is adjusted so that the vehicle speed V is maintained at the command speed Vst. Then return.
In step S280, an amount obtained by multiplying the speed difference (Vst−V) between the vehicle speed V and the command speed Vst by the feedback gain G1 is calculated as the fuel injection change amount Δf1. Then, the process proceeds to step S282.

In step S282, the fuel injection change amount Δf1 is added to or subtracted from the current fuel injection amount f, and the vehicle ECU 100 uses the adjusted fuel injection amount (f ± Δf1) to set the output torque of the engine 1 to the command speed Vst. Adjust to converge. Then return.
Next, the return control will be described with reference to FIG. This return control is performed by the return control unit 123 and accelerates the vehicle speed V to return to the command speed Vst.

In the return control, first, in step S360, it is determined whether or not the vehicle speed V is the command speed Vst. If the vehicle speed V is the command speed Vst, the process proceeds to step S362. If the vehicle speed V is not the command speed Vst, the process proceeds to step S380.
In step S362, the current fuel injection amount f is maintained, and the fuel injection amount is adjusted so that the vehicle speed V is maintained at the command speed Vst. Then return.

In step S380, an amount obtained by multiplying the speed difference (Vst−V) between the vehicle speed V and the command speed Vst by the feedback gain G2 is calculated as the fuel injection change amount Δf2. Then, control goes to a step S382.
In step S382, the fuel injection change amount Δf2 is added to the fuel injection amount f. That is, the fuel injection amount f is adjusted so that the vehicle speed V is accelerated to the command speed Vst and returned, and the vehicle ECU 100 increases the output torque of the engine 1 with the adjusted fuel injection amount (f + Δf2). Then return.

Next, inertial running control will be described with reference to FIG. This inertial traveling control is performed by the inertial traveling control unit 130 and controls the traveling in inertia with the clutch 2 disengaged and the engine speed as the idle speed.
In inertial running control, first, in step S600, the clutch 2 is disengaged. As a result, the output of the engine 1 is disconnected from the drive system. Then, the process proceeds to step S620.

In step S620, the engine speed is set to the idle speed. Thereby, the fuel consumption according to idle rotation speed is made. Then return.
Next, the vehicle speed, clutch connection / disconnection state, engine speed and engine output torque will be described with reference to FIG.
FIG. 11A shows the travel path on which the vehicle travels along the horizontal axis, and the vertical axis shows the altitude, and FIGS. 11B to 11E show the state of the vehicle corresponding to the road. Is the vehicle speed V on the vertical axis, (c) is the engagement / disengagement state of the clutch 2 on the vertical axis, (d) is the engine speed (Ne) on the vertical axis, and (e) is the output torque of the engine 1 on the vertical axis. Indicates.

The vehicle travels from the left end to the right end of the travel path in FIG.
In any of the following travel paths, the auto cruise SW 50 and the inertial travel permission SW 52 are in the ON state, the accelerator operation and the foot brake operation are not performed, and the control travel start condition is satisfied. .
First, at the point P0, the auto cruise SW 50 and the inertial travel permission SW 52 are turned on during traveling, and the command speed Vst is stored in the vehicle ECU 100. At the same time, normal auto-cruise traveling is performed in which the vehicle speed V is maintained at the command speed Vst.

Note that the travel path from the point P0 to the point P1 is flat (gradient value θ is 0), and the vehicle performs normal auto-cruise traveling.
At the point P1, the traveling road enters a downhill from a flat road. That is, the gradient value changes from 0 to negative. Therefore, the downhill coasting condition is established, and the vehicle is coasted with the clutch 2 disengaged and the engine speed set to the idle speed. Note that at the point P1, the vehicle speed V is the command speed Vst and is in the speed zone.

From point P1 to point P2, the travel path is a downhill (gradient value θ is negative), so the vehicle speed V increases as it approaches point P2. In addition, coasting is continued as long as the vehicle speed V is in the speed range.
The point P2 is a point that can be said to be the bottom of a valley where the traveling path changes from a downhill to an uphill (gradient value θ is negative to positive).

As shown in FIG. 11 (b), the vehicle speed V is not greater than the upper limit speed Vupp at the point P2, that is, not deviating from the speed range, and inertial traveling control is continuously performed.
From point P2 to point P3, the traveling road is uphill (gradient value θ is positive), so the vehicle speed V decreases as it approaches point P3. However, since the vehicle speed V is within the speed range, inertial running is continued.

At point P3, the slope value θ of the uphill increases on the travel path, that is, the gradient change rate dθ becomes positive.
The travel path from the point P3 to the point P5 is a travel path having a steeper slope value θ than the travel path from the point P2 to the point P3. In this travel route, the vehicle speed V during coasting travels at a rate that is greater than the rate of decrease from the point P2 to the point P3.

Between the point P3 and the point P5 (point P4), the vehicle speed V becomes smaller than the lower limit speed Vlow. That is, it is out of the speed band. Then, the vehicle ECU 100 switches the clutch 2 from the disconnected state to the connected state, and the return control by the return control unit 123 is started.
Return control is performed on the travel path from the point P4 to the point P5. By this return control, the vehicle speed V increases so as to accelerate to the command speed Vst and return. In this case, the output torque of the engine 1 is increased as shown in FIG. Here, the vehicle speed V reaches the command speed Vst at the point P5.

  The dashed line in FIG. 11 (d) shows the engine speed when the output torque is increased relatively small. Correspondingly, the output torque indicated by the dashed line in FIG. It shows a small rise. According to this, the increased amount of work when the region where the hatching in the lower right direction is hatched in the lower left direction raises the output torque relatively smaller than the increase in the work amount in the return control. There are more. That is, the amount of work that increases relative to the amount of work during normal auto cruise driving (output torque multiplied by time) is less in return control than when output torque is increased relatively small. . Therefore, the engine 1 is controlled in a region with good torque efficiency in the return control in which the vehicle speed V is accelerated to the command speed Vst, and fuel efficiency is improved.

The points P5 to P6 are travel paths having a gradient value θ1 larger than the gradient value θ from the point P3 to the point P5. Therefore, at the point P5, the gradient change rate dθ of the travel path is positive, and the auto-cruise mode control unit 120 switches from the return control to the normal auto-cruise travel control.
From point P5 to point P6, normal auto cruise traveling by the normal auto cruise traveling control unit 121 is performed.

The points P6 to P7 are travel paths having a gradient value θ2 smaller than the gradient value θ1 from the points P5 to P6. Therefore, at the point P6, the gradient change rate dθ of the traveling road becomes negative.
At the point P6, since the gradient value θ2 is positive and the gradient change rate dθ changes to negative, the peak determination unit 124 determines that the peak P is in front of the vehicle.
However, since the gradient value θ2 is equal to or greater than the gradient threshold θth and the precondition for the execution of the preparation control is not satisfied, the normal auto cruise traveling control is continuously performed from the point P6 to the point P7.

The points P7 to P9 are travel paths having a gradient value θ3 that is smaller than the gradient value θ2 from the points P6 to P7. Therefore, at the point P7, the gradient change rate dθ of the traveling road becomes negative. Of course, also at the point P7, the top determination unit 124 determines that there is a top P in front of the vehicle.
Further, since the gradient value θ3 is smaller than the gradient threshold θth, a precondition for performing the preparation control is satisfied. For this reason, the auto cruise mode control unit 120 switches from normal auto cruise control to preparation control.

Therefore, at the point P7, the preparation control by the preparation control unit 122 is started, and the pre-top inertia traveling start condition determination by the inertia traveling start determination unit 125 is started.
In the determination of the condition for starting the coasting before the peak, the point of the peak P is calculated based on the gradient value θ, the gradient change rate dθ, and the vehicle speed V. That is, the calculation of the summit P is to estimate and calculate a point P10 described later. Further, the vehicle speed Vp at the top P point when coasting is started at the present time is calculated as needed. When the calculated vehicle speed Vp at the summit P is equal to or higher than the lower limit speed Vlow, the summit-prediction travel start condition determination is established.

From point 7 to point P8, the vehicle speed V is increased toward the upper limit speed Vupp as shown in FIG. 11 (b), and the output torque of the engine 1 is also increased as shown in FIG. 11 (e).
From point P8 to point P9, the preparation control unit 122 maintains the vehicle speed V at the upper limit speed Vupp.
The point P9 is a point where the coasting end determination unit 125 calculates that the vehicle speed Vp at the top P is equal to or higher than the lower limit speed Vlow, and the pre-top coasting traveling start condition is satisfied.

Therefore, at the point P9, the clutch 2 is switched from the connected state to the disconnected state by the vehicle ECU 100, the preparation traveling by the preparation control unit 123 is switched to the inertia traveling by the inertia traveling control unit 130, and the inertia traveling control unit 130 is switched. As a result, the engine speed is reduced to the idle speed.
The point P9 to the point P10 are smaller than the gradient value θ3 from the point P7 to the point P9, have a positive gradient value θ, and the vehicle speed V decreases from the point P9 to the point P10.

The point P10 is a point where the gradient value θ of the traveling road changes from positive to negative and has a gradient value of 0.
At the point P10, as shown in FIG. 11 (b), the vehicle speed V is in the speed zone, so the coasting is continuously performed.

  Therefore, according to the vehicle travel control apparatus of this embodiment, when it is determined that the top P is in front of the vehicle, the change in the vehicle speed V when the vehicle starts coasting is estimated, and the vehicle In order to set the vehicle speed Vp at the time of reaching the lower limit speed Vlow or more as a pre-top inertia running start condition, the inertial driving is started from the front of the top P in a range where the vehicle speed V does not drop significantly (lower limit speed Vlow or more). can do. Thereby, the frequency which implements coasting can be increased and a fuel consumption can be improved.

In many cases, there is a downhill next to the top P of the uphill. In this case, coasting can be continuously performed from the front of the top P to the subsequent downhill, and the vehicle ECU 100 disengages the clutch 2. Contact control can be performed smoothly. It is also advantageous for improving fuel consumption.
If the vehicle speed V is in a speed range having a range defined by the upper limit speed Vupp and the lower limit speed Vlow, if the coasting is continuously performed from before the top P to the subsequent downhill, the vehicle speed V is Usually, it decreases from before the summit P to the summit P, and when it increases on the subsequent downhill and exceeds the upper limit speed, the coasting is ended, but the traveling speed of the vehicle decreases when entering the downhill Therefore, since the vehicle speed V when entering the downhill has a margin with respect to the upper limit speed Vupp, coasting can be performed over a longer section. Thereby, a fuel consumption can be improved more.

In addition, when the slope value θ is positive and the slope change rate dθ is negative, the summit determination unit 124 determines that the summit P is in front of the vehicle, so that the summit P is surely before the summit P. Can be determined.
In addition, when the vehicle speed V is within a speed band having a width defined by the upper limit speed Vupp and the lower limit speed Vlow with the command speed Vst as the center, the inertial running is continued. It is possible to carry out inertial running in an easy speed range, and to improve fuel efficiency while ensuring drivability.

  Further, when it is determined that there is a peak P ahead of the vehicle on the uphill, the vehicle speed V is increased from the command speed Vst to the upper limit speed Vupp to perform coasting preparation preparation control. The vehicle speed Vp at the time of arrival can be increased according to the speed difference between the command speed Vst and the upper limit speed Vupp, and the inertia traveling is performed from the front with respect to the top P, and the period during which the inertia traveling is performed is lengthened. be able to. This is also advantageous in improving fuel consumption.

When the vehicle speed V is increased from the command speed Vst to the upper limit speed Vupp, the engine is controlled in a torque range with a good fuel consumption rate, so that the fuel consumption of the entire traveling can be improved.
Further, when the vehicle speed V deviates from the speed range, coasting is terminated, so that it is possible to avoid a reduction in drivability.
When the vehicle speed V becomes higher than the upper limit speed Vupp and the coasting is terminated, for example, further acceleration on a downhill can be prevented, and safety can be ensured.

  Further, when returning to normal auto-cruise running where the inertial running is finished below the lower limit speed Vlow and the vehicle runs at the command speed Vst, the output increment of the engine 1 is set to be larger than the output increment during normal auto-cruise running. Since the output is controlled, that is, the feedback gain G1 at the time of normal auto cruise traveling (normal time) is increased to the feedback gain G2, it is possible to promptly shift to normal odd cruise traveling. In this case, since the engine 1 is controlled so that the output torque required for the traveling to return after accelerating the current vehicle speed V to the command speed Vst is in a torque range with a good fuel consumption rate, the fuel efficiency of the entire traveling is improved. Can be made.

[Others]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.
In the above-described embodiment, the auto-cruise mode control unit (constant speed traveling control unit) 120 includes the top determining unit (top determining unit) 124 and the inertia traveling start determining unit (inertial traveling start determining unit) 125. The vehicle ECU may be configured to correspond to both the constant speed travel control unit and the inertia travel control unit, and the vehicle ECU may include a top determination unit and an inertia travel start determination unit.

  In addition, the clutch 2 is disengaged and the output of the engine 1 is disconnected from the power system and coasting is shown. Instead, the transmission stage of the transmission 3 is switched to the neutral gear and the output of the engine 1 is changed. Inertia traveling may be performed by disconnecting from the power system. When the gear position of the transmission 3 is switched to the neutral gear, the output of the engine 1 is transmitted to the power transmission mechanism (propeller shaft 4, differential gear 5, drive shaft 6, drive wheel 7) downstream of the transmission 3. In addition, coasting can be performed. According to this configuration, coasting can be performed even in a vehicle that does not include a clutch, and fuel efficiency can be improved.

Further, the feedback gain G2 when the vehicle speed V increases in the return control and the preparation control may be set differently. In this case, the fuel injection change amount Δf2 is also different.
Further, when the vehicle speed V is maintained at a predetermined speed or when the vehicle speed V is increased, the fuel injection change amounts Δf1 and Δf2 are adjusted according to the speed deviation between the vehicle speed V and the predetermined speed. An amount of fuel injection change Δf may be applied. In this case, the fuel injection change amount Δfii when the vehicle speed V increases in the return control and the preparation control is set to be larger than the fuel injection change amount Δfi when the normal auto cruise traveling control and the preparation control maintain the vehicle speed V.

Further, when the vehicle speed V is increased in the return control and the preparation control, for example, the optimum torque value considering the fuel consumption and acceleration corresponding to the traveling state such as the vehicle speed V is stored in advance, and the output torque of the engine 1 corresponds to the traveling state. The fuel injection amount f0 may be set so as to obtain a predetermined torque.
In addition, when the driver is willing to accelerate or decelerate or when the SWs 50 and 52 are turned off, the control traveling such as the auto cruise mode traveling or the inertia traveling is immediately interrupted and the normal traveling by the driver is performed. However, the condition that the controlled travel is further interrupted can be that the distance from the preceding vehicle is equal to or less than a predetermined value or that the relative speed with respect to the preceding vehicle is equal to or greater than the predetermined value. According to this configuration, safety can be further ensured, and fuel consumption is improved.

  The vehicle travel control device of the present invention can be applied not only to large vehicles such as trucks or buses but also to small vehicles such as passenger cars.

1 Engine 2 Clutch (Power connection / disconnection means)
3 Transmission (power connection / disconnection means)
4 Propeller shaft 5 Differential gear 6 Drive shaft 7 Drive wheel 10 Gradient sensor (gradient detection means)
20 APS
30 Foot brake SW
40 Vehicle speed sensor 50 Auto cruise SW (constant speed running command means)
52 Inertia travel permission SW (Inertia travel permission means)
100 vehicle ECU
105 Control traveling start determination unit 110 Gradient change rate calculation unit (gradient change rate detection means)
120 Auto-cruise mode control unit 121 Normal auto-cruise traveling control unit (constant speed traveling control means)
122 Preparation control unit (preparation control means)
123 Return control unit (return control means)
124 Top determination section (top determination means)
125 Inertia travel start determination unit (inertia travel start determination means)
130 Inertia travel control unit (inertia travel control means)
131 Inertia travel end determination unit (inertia travel end determination means)

Claims (6)

Engine,
Power connection / disconnection means interposed between the engine and the drive wheel;
In a vehicle provided with inertial running control means for controlling the power connection / disconnection means to a power cutoff state and starting inertial running when the inertial running start condition is satisfied,
The inertial running start condition includes that the traveling path of the vehicle is a downhill or an uphill that satisfies a predetermined condition,
The inertial running control means includes
A top judging means for judging whether or not there is a top of an uphill in front of the vehicle;
When it is determined by the peak determination means that the peak is present, a change in the traveling speed of the vehicle when the vehicle starts the inertia traveling is estimated, and the vehicle reaches the peak by the inertia traveling. A vehicle travel control device comprising: inertial travel start determining means for determining the start of the inertial travel based on the predetermined condition that the travel speed when the vehicle travels is equal to or higher than a lower limit speed. The vehicle is
Gradient detecting means for detecting the gradient of the travel path on which the vehicle travels;
A gradient change rate detecting means for detecting a change rate of the gradient,
The summit determination means includes:
2. The vehicle travel control device according to claim 1, wherein when the slope is positive and the rate of change is negative, it is determined that the top is present. The vehicle has a constant speed traveling command means for automatically traveling the vehicle at a constant speed;
When a constant speed travel command is commanded by the constant speed travel command means, a constant speed travel control is performed to operate the output of the engine to maintain the travel speed of the vehicle at the commanded command speed. Means,
The inertial traveling control means starts the inertial traveling when the inertial traveling start determining means determines the inertial traveling start during the constant speed traveling control by the constant speed traveling control means, and the traveling speed of the vehicle However, as long as it is within a speed band having a width defined by an upper limit speed that is higher than the command speed by a preset speed difference and a lower limit speed that is lower than the command speed by a preset speed difference, The vehicle travel control device according to claim 1, wherein the inertial travel control is continued. During the constant speed traveling control by the constant speed traveling control means, if the summit determining means determines that the top is present, the traveling speed of the vehicle is increased from the command speed to a speed higher by a preset speed difference. The vehicle travel control apparatus according to claim 3, further comprising a preparation control unit configured to perform preparation control for the inertia traveling. The inertial running control means includes
During the inertial traveling control, when the traveling speed of the vehicle deviates from the speed band, the vehicle includes inertial traveling end determination means for determining the end of the inertial traveling control,
The constant speed traveling control means includes:
5. The vehicle travel according to claim 3, wherein when the constant speed travel is commanded, the output of the engine is operated by feedback control based on a deviation between the actual travel speed of the vehicle and the command speed. Control device. During the inertial travel by the inertial travel control means, the inertial travel end determination means determines the end of the inertial travel control when the travel speed of the vehicle falls below the speed band, and the constant speed travel control is performed. When returning, the output increment is larger than the output increment when the vehicle travel speed is increased to the command speed during the constant speed travel control until the vehicle travel speed increases to the command speed. The vehicle travel control apparatus according to any one of claims 3 to 5, further comprising return means for controlling the output of the engine.

Images