JP2018062310A - Vehicle control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle control device that can suppress coasting control from being released in short time by starting unnecessary coasting control.SOLUTION: A coasting control ECU 100, which is configured to execute coasting control, by which a clutch mechanism 50 for transmitting output of an engine 10 to a driving wheel is switched from a connection state where the output of the engine 10 is transmitted to the driving wheel into a non-connection state where the output of the engine 10 is not transmitted to the driving wheel, during coasting running of a vehicle, determines whether or not variations of acceleration of the vehicle are above a specified value after stepping-on of an accelerator pedal is released; and when determining that the variations of the acceleration of the vehicle are above the specified value, sets a stand-by time during which a state where the coasting control is not started is maintained since the determination is maintained to be longer than when the variations of the acceleration of the vehicle are less than the specified value.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a vehicle control device.

  Conventionally, coasting control is known as an example of vehicle control for improving the fuel efficiency of a vehicle. In this coasting control, transmission of power from the engine to the drive wheels is interrupted when a coasting control start condition including, for example, stabilization of the vehicle speed after the accelerator pedal is released is satisfied. As a result, the vehicle performs inertial running while reducing the influence of mechanical friction loss of the engine, that is, engine friction, thereby improving fuel efficiency.

  As a vehicle control device that executes such coasting control, for example, the device described in Patent Document 1 is a method that allows the driver to slightly depress the accelerator pedal even though it is properly timed to shift to coasting control. When the vehicle has not shifted to coasting control due to this, the driver is informed accordingly. And since the shift to coasting control is promoted by such a configuration, opportunities for improving fuel efficiency by coasting control can be increased.

JP 2014-113863 A

  By the way, in the apparatus described in the above document, when the road on which the vehicle is traveling is a flat road and the slope of the road is relatively small, the vehicle speed after the accelerator is off tends to be stable, and thus the coasting control is performed. It's easy to do. At this time, if the road on which the vehicle is traveling during the coasting control changes from a flat road to a downhill, the coasting control does not cause engine friction to act on the drive wheels. The brake operation, which is a kind of release condition, is easily performed. For this reason, even when coasting control is started during traveling on a flat road, coasting control is stopped at a short time interval after the road ahead changes to a downhill. As a result, coasting control is released in a short time, which may cause the driver to feel uncomfortable.

  Such a problem occurs not only when the road on which the vehicle is traveling changes from a flat road to a downhill, but also when the road on which the vehicle travels changes from a flat road to an uphill. That is, when the road on which the vehicle is running during coasting control changes from a flat road to an uphill, torque is not transmitted from the engine to the drive wheels, so the speed of the vehicle decreases sharply and is a kind of conditions for canceling coasting control. This makes it easier to execute the accelerator operation. Therefore, even when coasting control is started during traveling on a flat road, coasting control is stopped at a short time interval after the road ahead is changed to an uphill. As a result, coasting control is released in a short time, which may cause the driver to feel uncomfortable.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a vehicle control device capable of suppressing the coasting control from being released in a short time due to the start of unnecessary coasting control. It is to provide.

  In a vehicle control device that solves the above-described problems, a power transmission mechanism that transmits engine output to drive wheels during inertial running of the vehicle is driven from a coupled state in which engine output is transmitted to drive wheels. A coasting control unit that performs coasting control for switching to a non-coupled state that is not transmitted to the wheel, and the coasting control unit determines whether or not the change value of the acceleration of the vehicle after the accelerator pedal is released is greater than or equal to a specified value When the acceleration change value is equal to or greater than the specified value, the standby state in which the coasting control is not started from the determination time than when the acceleration change value is less than the specified value is determined. Set a longer period.

  When the change value of the acceleration of the vehicle after the depression of the accelerator pedal is released is greater than or equal to the specified value, there is a high possibility that the slope of the road on which the vehicle is traveling has changed. Therefore, as described above, in such a case, after determining that the change value of the acceleration of the vehicle is equal to or greater than the specified value, the period during which the coasting control is not started is set longer. Thereby, it becomes difficult to start coasting control unnecessarily, and as a result, release of coasting control in a short time can be suppressed.

  In the vehicle control device, the standby period is a determination period for performing a determination process for determining whether or not the coasting control can be started, and the coasting control unit is configured so that the acceleration change value is It is preferable that an initial value is set in the determination period when the value is less than a specified value, and an additional period is added to the initial value of the determination period when the acceleration change value is equal to or greater than the specified value.

  According to the above configuration, when the change value of the acceleration of the vehicle after the depression of the accelerator pedal is released is equal to or greater than the specified value, and the slope of the road on which the vehicle is traveling is considered to change. The determination period for determining whether or not coasting control can be started after the accelerator pedal is released is extended compared to when the change value of the acceleration of the vehicle is less than the specified value. As a result, after the road gradient changes, an accelerator operation, a brake operation, or the like, which is a kind of vehicle operation that makes the start of coasting control after the accelerator is turned off unsuccessful, is easily performed during the determination period. As a result, coasting control is less likely to be started unnecessarily, and as a result, release of coasting control in a short time can be suppressed.

  On the other hand, even if the change in acceleration of the vehicle after the accelerator pedal is released is greater than or equal to the specified value, the section where the road gradient changes is not long enough to require coasting control to be released. There is a possibility. In this case, as described above, even if the determination period for determining whether or not coasting control can be started after the accelerator pedal is released is extended, the accelerator operation and the brake operation are performed within the extended determination period. If the above is not executed, the transition to coasting control is started after the determination period has elapsed. Thereby, the presence or absence of the shift to coasting control can be determined according to the actual situation.

In the vehicle control device, it is preferable that the coasting control unit prohibits the shift to the coasting control when the acceleration change value is equal to or greater than the specified value.
According to the above configuration, when the change value of the acceleration of the vehicle after the depression of the accelerator pedal is released is not less than the specified value and the slope of the road on which the vehicle is traveling is considered to change, the coasting control Prohibit transition to. As a result, coasting control is less likely to be started unnecessarily, and as a result, release of coasting control in a short time can be suppressed.

  In the vehicle control device, the coasting control unit calculates a change value of the acceleration of the vehicle per unit time, and an average value of the change values of the acceleration of the vehicle in a plurality of unit times is equal to or more than the specified value. It is preferable to change the waiting period.

  According to the above configuration, the road section where the slope of the road locally changes in the road section where the vehicle is traveling is obtained by comparing the average value of the change values in the acceleration of the vehicle over a plurality of unit times. Even if it is included, it can be suppressed that the presence or absence of the change in the standby period due to the road section is erroneously determined.

  In the vehicle control device, the coasting control unit stores the acceleration of the vehicle per unit time or the change value of the acceleration of the vehicle per unit time in the storage unit as acceleration information, and the depression of the accelerator pedal is released. It is preferable that the acceleration information is read from the storage unit at every subsequent unit time, and an average value of change values in the acceleration of the vehicle in a plurality of unit times is calculated based on the read acceleration information.

  According to the above configuration, after the depression of the accelerator pedal is released, the vehicle acceleration information for each unit time stored in the storage unit in advance is read from the storage unit, and based on the read acceleration information, An average value of change values in the acceleration of the vehicle per unit time is calculated. Therefore, it is possible to grasp the gradient of the road on which the vehicle is traveling from an earlier stage compared to the case where the change value of the acceleration of the vehicle per unit time is started after the accelerator pedal is released. It becomes.

The block diagram which shows schematic structure of the vehicle to which the vehicle control apparatus of this Embodiment is applied. (A) is a graph which shows the time transition of the acceleration of the vehicle when driving | running | working on a flat road, (b) is the transition of the variation | change_quantity of the acceleration of the vehicle after accelerator off when driving | running | working on a flat road. Graph showing. (A) is a graph showing the time transition of the acceleration of the vehicle when moving from a flat road to a downhill, and (b) is the amount of change in the acceleration of the vehicle after the accelerator is turned off when moving from a flat road to a downhill. The graph which shows transition of. (A) is a graph showing the time transition of the acceleration of the vehicle when moving from a flat road to an uphill, and (b) is the amount of change in the acceleration of the vehicle after the accelerator is turned off when moving from a flat road to an uphill. The graph which shows transition of. The flowchart which shows the process sequence of the coasting control start process which the vehicle control apparatus of the embodiment performs. The flowchart which shows the process sequence of the coasting control start process which the vehicle control apparatus of the embodiment performs. (A) is a schematic diagram for explaining the operation mode of coasting control when the traveling position of the vehicle shifts from a flat road to a downhill in the conventional vehicle control device, and (b) The schematic diagram for explaining an example of the operation mode of coasting control when the travel position of the vehicle shifts from a flat road to a downhill, (c) The schematic diagram for demonstrating another example of the operation mode of coasting control in a vehicle control apparatus, when the driving | running | working position of a vehicle transfers to a downhill from a flat road. (A) is a schematic diagram for explaining the operation mode of coasting control when the traveling position of the vehicle shifts from a flat road to an uphill in the conventional vehicle control device, and (b) is the same as the embodiment. The schematic diagram for explaining an example of the operation mode of coasting control when the travel position of the vehicle shifts from a flat road to an uphill in the vehicle control device of the embodiment, FIG. The schematic diagram for demonstrating another example of the operation | movement aspect of coasting control in a vehicle control apparatus, when the driving position of a vehicle transfers to an uphill from a flat road.

Hereinafter, an embodiment of a vehicle control device will be described with reference to the drawings.
As shown in FIG. 1, the vehicle control device of the present embodiment is operated by a coasting control ECU 100 (electronic control device) that executes coasting control as a kind of vehicle control when a predetermined start condition is satisfied during traveling of the vehicle. It is configured. The coasting control ECU 100 is connected to other ECU groups via a vehicle network NW including, for example, a CAN (controller area network).

  The other ECU group includes a plurality of in-vehicle ECUs that control the operation of various on-vehicle devices. For example, the engine ECU 110 that controls the operation of the engine 10, the brake ECU 120 that controls the operation of the brake, and the automatic transmission 20 A transmission ECU 130 for controlling the operation is included. The engine ECU 110 is connected to an accelerator opening sensor 30 that detects the amount of depression of the accelerator pedal by the driver. The brake ECU 120 is connected to an acceleration sensor 40 that detects the acceleration of the vehicle.

  And every time the coasting control ECU 100 acquires the acceleration of the vehicle from the acceleration sensor 40 through the brake ECU 120 and the vehicle network NW, the calculation unit 101 calculates the change value of the acceleration of the vehicle per unit time. In addition, coasting control ECU 100 stores the calculated change value of the vehicle acceleration in storage unit 102. Further, every time the coasting control ECU 100 stores the change value of the acceleration of the vehicle in the storage unit 102, the coasting control ECU 100 reads out the change value in the acceleration of the vehicle in each unit time from the past to the present from the storage unit 102. At the same time, an average value of the change values in the acceleration of the vehicle in the plurality of unit times is calculated. Further, the coasting control ECU 100 performs a comparison determination between the average value of the change value of the acceleration of the vehicle and the specified value through the determination unit 103. When the coasting control ECU 100 determines that the average value of the change values in the acceleration of the vehicle is greater than or equal to the prescribed value, the coasting control ECU 100 maintains a state in which coasting control is not started from the judgment time than when the average value is less than the prescribed value. Set a longer time.

  Here, in the present embodiment, as an example, in order for the coasting control ECU 100 to start coasting control, it is assumed that the coasting control start preparation conditions listed in the following (a) to (c) are satisfied. Become.

(A) The shift lever is in the D (drive) position.
(B) The vehicle speed is equal to or higher than a specified value.
(C) The driving support function is operating normally.

  And while the coasting control start preparation conditions are satisfied, the coasting control ECU 100 causes the accelerator opening input from the accelerator opening sensor 30 through the engine ECU 110 and the vehicle network NW to be less than a predetermined opening threshold. When the accelerator pedal is depressed, it is detected that the depression of the accelerator pedal, in other words, the accelerator is off. The coasting control ECU 100 starts coasting control on the condition that the vehicle speed after the accelerator is turned off is stabilized for a certain period of time. At this time, as described above, coasting control ECU 100 determines that the average value of the change values in the acceleration of the vehicle over a plurality of unit times is greater than or equal to the specified value, compared to when the average value is less than the specified value. The standby period for maintaining the coasting control not starting from time is set longer.

  Specifically, as shown in FIGS. 2A and 2B, the coasting control ECU 100 periodically detects the vehicle acceleration detected through the acceleration sensor 40 when the vehicle is traveling from the brake ECU 120 through the vehicle network NW. To get to. Further, every time the coasting control ECU 100 acquires the acceleration of the vehicle, the coasting control ECU 100 calculates a change value of the acceleration of the vehicle per unit time, and stores the calculated change value of the acceleration of the vehicle in the storage unit 102.

  The coasting control ECU 100 periodically acquires the accelerator opening detected through the accelerator opening sensor 30 during traveling of the vehicle from the engine ECU 110 through the vehicle network NW. The coasting control ECU 100 detects accelerator off when the accelerator opening thus obtained becomes less than a predetermined opening threshold. Further, when the coasting control ECU 100 detects the accelerator off, the coasting control ECU 100 reads the change values in the acceleration of the vehicle at each unit time in a plurality of unit times from the past to the present from the storage unit 102, and also displays the change values of the accelerations of these vehicles. The average value is calculated. In the example shown in FIGS. 2A and 2B, the coasting control ECU 100 sets three unit times from the past to the time point when the accelerator-off is detected as one section t0, and changes in the acceleration of the vehicle. The average value of is calculated. After that, the coasting control ECU 100 calculates an average value of the change values of the acceleration of the vehicle as needed, with three unit times from the past to the present as one section t1 to t4 for each unit time.

  At this time, as in the example shown in FIG. 2A, when the environment of the road on which the vehicle is traveling is maintained as a flat road, the vehicle is traveling in the respective sections t0 to t4 after the accelerator is turned off. The slope of the road hardly changes. Therefore, as shown in FIG. 2 (b), the change value of the acceleration of the vehicle in each section t0 to t4 is maintained substantially at “0 (zero)”, and is set up and down with “0 (zero)” as a reference. There is a tendency to fall within the range of the specified value (the range from the negative specified value “−X1” to the positive specified value “X1”).

  On the other hand, as in the example shown in FIG. 3A, when the environment of the road on which the vehicle is traveling after the accelerator is turned off changes from a flat road to a downhill, the vehicle reaches a point where the road gradient changes. Then, the acceleration of the vehicle thereafter increases gradually. At this time, the average value of the change values of the acceleration of the vehicle over a plurality of unit times from the past to the present gradually increases by the increase of the acceleration of the vehicle at the current time. Therefore, as shown in FIG. 3B, the average value of the change values of the vehicle acceleration gradually increases with the passage of time after passing through a point where the road gradient changes. At a certain point in time, the average value of the change value of the vehicle acceleration tends to deviate from the range of the specified value described above. In the example shown in FIG. 3B, the end of “section t4” is a point in time that falls outside the range of the specified value described above.

  Similarly, as in the example shown in FIG. 4A, when the environment of the road on which the vehicle is traveling after the accelerator is off shifts from a flat road to an uphill, the vehicle reaches a point where the road gradient changes. Then, the acceleration of the vehicle thereafter decreases gradually. At this time, the average value of the change values of the vehicle acceleration in a plurality of unit times from the past to the present gradually decreases by the amount that the vehicle acceleration at the present time decreases. For this reason, as shown in FIG. 4B, the average value of the change values of the vehicle acceleration gradually decreases (the negative value increases) as time elapses after passing the point where the road gradient changes. ). And the average value of the change value of the acceleration of the vehicle at a certain point in time (section t4 in the example shown in FIG. 4B) tends to deviate from the range of the specified value described above. In the example shown in FIG. 4B, the end point of the “section t4” is a time point that falls outside the range of the specified value described above.

  Therefore, the coasting control ECU 100 determines whether or not the average value of the change values of the acceleration of the vehicle in the plurality of unit times is within a specified value range as information reflecting the slope of the road on which the vehicle is traveling. That is, it is determined whether or not it is equal to or greater than a specified value.

  The coasting control ECU 100 determines whether the coasting control after the accelerator is off can be started when it is determined that the average value of the change values of the acceleration of the vehicle after the accelerator is off is less than the specified value. An initial value is set as a determination period for performing the process, that is, a determination period for determining whether or not the vehicle speed is stable after the accelerator is turned off. On the other hand, coasting control ECU 100 extends the determination period by adding an additional period to the above-described initial value when determining that the average value of the change in acceleration of the vehicle after the accelerator is off is greater than or equal to the specified value. To do.

  1, when the coasting control ECU 100 starts coasting control, the coasting control ECU 100 is a part of the automatic transmission 20 and includes a clutch mechanism 50 that connects the engine 10 and the automatic transmission 20 so as to transmit power. The meshing is released through the transmission ECU 130 so that the output of the engine 10 is not transmitted to the automatic transmission 20. As a result, the mechanical friction loss of the engine 10, that is, engine friction, does not act on the drive wheels via the automatic transmission 20, and the fuel consumption is improved when the vehicle is coasting. In coasting control, in order to improve the fuel efficiency of the vehicle, it is preferable to reduce the idle speed of the engine 10 from the normal time with the clutch mechanism 50 disengaged. In coasting control, instead of releasing the engagement of the clutch mechanism 50, the automatic transmission 20 may be in a neutral state.

  Next, a specific processing procedure of coasting control start processing executed by coasting control ECU 100 of the above embodiment will be described. Here, coasting control ECU 100 executes coasting control start processing on the condition that the ignition switch of the vehicle is on.

  As shown in FIGS. 5 and 6, in the coasting control start process, first, the coasting control ECU 100 performs the above-described coasting based on various vehicle data input from other ECU groups connected via the vehicle network NW. It is determined whether or not a control start preparation condition is satisfied (step S10).

  When the coasting control ECU 100 determines that the start preparation conditions for coasting control are satisfied (step S10 = YES), the accelerator opening input from the accelerator opening sensor 30 via the engine ECU 110 is a predetermined opening degree. It is determined whether or not the accelerator pedal is released, that is, whether or not the accelerator is off, based on whether or not it is less than the degree threshold (step S11).

  Further, when the coasting control ECU 100 determines that the accelerator is off (step S11 = YES), the change value of the acceleration of the vehicle at each unit time in a plurality of unit times from the past to the present is read from the storage unit 102. Obtain (step S12).

  If the determination period has not yet been extended (step S13 = YES), coasting control ECU 100 determines that the average value of the change values of the vehicle acceleration acquired in step S12 is equal to or greater than the specified value (range of specified values). It is determined whether or not (step S14). At this time, coasting control ECU 100 sets the determination period to an initial value (step S15) when the average value of the change values of the acceleration of the vehicle is less than the prescribed value (step S14 = NO). On the other hand, coasting control ECU 100 extends the determination period by adding an additional period to the above-described initial value when the average value of the change values of the acceleration of the vehicle thus acquired is equal to or greater than the specified value (step S14 = YES). (Step S16).

  Subsequently, the coasting control ECU 100 starts counting the timer (step S17), and then whether or not the amount of change per unit time in the vehicle speed is within a predetermined range, in other words, whether or not the vehicle speed is stable. (Step S18).

  When coasting control ECU 100 determines that the vehicle speed is stable (step S18 = YES), the count value of the timer that started timing in previous step S17 is the determination set in previous step S15 or step S16. It is determined whether or not the period has been reached (step S19).

  In this case, coasting control ECU 100 determines that the count value of the timer has not reached the determination period (step S19 = NO), unless the ignition switch of the vehicle is turned off (step S20). Return to S10.

  Thereafter, until the count value of the timer reaches the determination period, coasting control ECU 100 determines the coasting control start preparation condition (step S10), determines whether or not the accelerator pedal is depressed (step S11), vehicle speed The process for determining the presence or absence of stability in step S18 is repeated. The coasting control ECU 100 resets the count value of the timer when any one of these determination processes is negative (step S21), and extends the determination period in the previous step S16. If so, the determination period is reset to the initial value (step S22). On the other hand, coasting control ECU 100 starts coasting control (step S23) when the count value of the timer reaches the determination period while all of these determination processes maintain affirmative determination (step S19 = YES). The coasting control start process shown in FIGS. 5 and 6 is terminated.

  Next, the operation of coasting control ECU 100 according to the present embodiment will be described below, focusing on the operation when the determination period after the accelerator is turned off is changed according to the environment of the road on which the vehicle is traveling.

When starting the coasting control, it is usually a condition that the vehicle speed after the accelerator is off is stabilized for a certain period of time while the coasting control start preparation condition is satisfied.
At this time, as shown in FIG. 7A, in the conventional example, the determination period regarding the presence or absence of the stability of the vehicle speed after the accelerator is off is uniformly set without considering the road environment after the accelerator is off. . In this case, when the road environment after the accelerator is off transitions from a flat road to a downhill, coasting control is started when a preset determination period has elapsed after the accelerator is off while the vehicle is traveling downhill. Then, since the vehicle travels while accelerating the downhill, there is a high possibility that the brake operation is immediately performed. In particular, since the engine friction does not act along with the coasting control, the acceleration of the vehicle is promoted, so that the possibility that the above-described brake operation is immediately performed is significantly increased. The coasting control is released by this brake operation. That is, coasting control is started and released in a short time while accelerator off and brake operations are performed in a series of processes in which the environment of the road on which the vehicle is running transitions from a flat road to a downhill after the accelerator is turned off. This was done during the period, and there was a risk of giving the driver a sense of incongruity.

  In this regard, as shown in FIG. 7 (b), in this embodiment, the change in the gradient of the road on which the vehicle is traveling is monitored based on the change in the acceleration of the vehicle after the accelerator is turned off. When it is considered that there is a high possibility that the change is large, the determination period after the accelerator is off is extended. As a result, the possibility that the brake operation is performed for the deceleration of the vehicle traveling while accelerating the downhill during the extended determination period is increased, and the vehicle speed changes due to the brake operation. Alternatively, the coasting control start condition is not satisfied because the brake operation is set as the coasting control release condition. As a result, the coasting control is maintained in a state of being canceled as a whole in a series of processes in which the environment of the road on which the vehicle is traveling shifts from a flat road to a downhill after the accelerator is turned off. It is possible to suppress the release from being performed in a short time.

  Further, as shown in FIG. 7 (c), in the present embodiment, even when the slope of the road after the accelerator is off is considered to change greatly from a flat road to a downhill, the downhill is braked. Since the road length is not long enough to require operation, coasting control is started when no vehicle operation is performed to prevent the start of coasting control during the extended determination period. Thereby, the presence or absence of the shift to coasting control is determined according to the actual situation.

  Similarly, as shown in FIG. 8A, conventionally, when the environment of the road after the accelerator is turned off shifts from a flat road to an uphill, the accelerator is off while the vehicle is traveling on the uphill. Later, coasting control is started when a preset determination period has elapsed, and after that, the vehicle travels while decelerating the uphill, so that there is a high possibility that the accelerator operation will be immediately performed. Then, coasting control is released by this accelerator operation. In other words, coasting control is started and released in a short period of time while the accelerator is turned off and on during a series of processes in which the environment of the road on which the vehicle is traveling changes from a flat road to an uphill after the accelerator is turned off. This was done during the period, and there was a risk of giving the driver a sense of incongruity.

  In this regard, as shown in FIG. 8B, in the present embodiment, the change in the gradient of the road on which the vehicle is traveling is monitored based on the change in the acceleration of the vehicle after the accelerator is turned off. When it is considered that there is a high possibility that the change is large, the determination period after the accelerator is off is extended. As a result, during this extended determination period, there is a high possibility that the accelerator operation will be performed for reacceleration of the vehicle traveling while decelerating the uphill, and the vehicle speed changes due to this accelerator operation. In other words, the coasting control start condition is not satisfied because the accelerator operation is set as the coasting control cancellation condition. As a result, the coasting control is consistently released in a series of processes in which the environment of the road on which the vehicle is running transitions from a flat road to an uphill after the accelerator is turned off, and the coasting control starts. It is possible to prevent the release from switching in a short time.

  Further, as shown in FIG. 8 (c), in the present embodiment, even when the slope of the road after the accelerator is off is considered to change greatly from a flat road to an uphill, the uphill is an accelerator. Since the road length is not long enough to require operation, coasting control is started when no vehicle operation is performed to prevent the start of coasting control during the extended determination period. Thereby, the presence or absence of the shift to coasting control is determined according to the actual situation.

As described above, according to the present embodiment, the following effects can be obtained.
(1) The coasting control ECU 100 does not start coasting control from the time of determination when the change value of the acceleration of the vehicle after the accelerator is turned off, which is input from the acceleration sensor 40, is greater than or equal to the specified value than when it is less than the specified value. Set a longer waiting period for maintaining the state. Thereby, it becomes difficult to start coasting control unnecessarily, and as a result, release of coasting control in a short time can be suppressed.

  (2) The coasting control ECU 100 determines whether the vehicle speed is stably maintained after the accelerator is turned off when the change value of the acceleration of the vehicle after the accelerator is turned off, which is input from the acceleration sensor 40, is equal to or greater than a specified value. Extend the judgment period. This not only makes it difficult to start coasting control unnecessarily, but also makes it possible to determine whether or not to shift to coasting control according to the actual situation.

  (3) The coasting control ECU 100 calculates a change value of the acceleration of the vehicle every unit time, and after the accelerator is turned off when the average value of the change values of the acceleration of the vehicle in a plurality of unit times is equal to or more than a specified value. The determination period for determining whether the vehicle speed is maintained stably is extended. As a result, even if the road section on which the vehicle is traveling includes a road section where the gradient of the road changes locally, it is erroneously determined whether the determination period has changed due to the road section. Can be suppressed.

  (4) The coasting control ECU 100 stores a change value of the acceleration of the vehicle for each unit time in the storage unit 102, and the acceleration of the vehicle in each unit time in a plurality of unit times for every lapse of the unit time that follows when the accelerator is off. Is read from the storage unit 102, and an average value of the change values in the acceleration of the vehicle in the plurality of unit times is calculated. As a result, it is possible to grasp the gradient of the road on which the vehicle is traveling from an earlier stage as compared with the case where the change value of the acceleration of the vehicle per unit time is started after the accelerator is turned off.

In addition, the said embodiment can also be implemented with the following forms.
In the above embodiment, the coasting control ECU 100 stores the vehicle acceleration acquired from the acceleration sensor 40 per unit time in the storage unit 102, and a plurality of units from the past to the present each time the unit time has elapsed after the accelerator is turned off. The acceleration of the vehicle at each unit time in the unit time may be read from the storage unit 102 and the change value of the acceleration may be calculated.

  In the above embodiment, coasting control ECU 100 calculates an average value of change values in the acceleration of the vehicle over a plurality of unit times from the past to the present, and based on whether this average value is equal to or greater than a specified value. The determination period after accelerator off was changed. Instead, the coasting control ECU 100 determines whether or not the change value of the acceleration of the vehicle in each unit time is equal to or greater than a specified value every time the unit time after the accelerator is turned off, and based on the determination result The determination period after the accelerator is off may be changed. In this case, the coasting control ECU 100 calculates a change value of the acceleration of the vehicle every time the acceleration of the vehicle is input from the acceleration sensor 40 if the calculation processing performance is sufficiently secured, and compares it with the specified value. After the determination, the data may be discarded at any time. That is, the storage unit 102 of the coasting control ECU 100 does not necessarily have to secure a memory area for storing the acceleration of the acceleration sensor 40 and its change value.

  In the above embodiment, the coasting control ECU 100 changes the determination period after the accelerator is turned off according to the environment of the road after the accelerator is turned off. However, the determination element to be changed according to the road environment after the accelerator is off is not limited to the determination period regarding whether the vehicle speed is stable. That is, for example, by changing other determination elements constituting the coasting control start condition such as a speed range in which the vehicle speed is determined to be stable, the standby period for maintaining the coasting control not starting from the determination time is set longer. You may do it.

  In the above embodiment, coasting control ECU 100 determines that the slope of the road after the accelerator is off has changed significantly, rather than when it has been determined that the slope of the road after the accelerator is off has not changed much. As an example of a method for setting a long standby period for maintaining a state in which coasting control is not started from the time of determination, transition to coasting control may be prohibited.

  In the above embodiment, the coasting control ECU 100 determines the propriety of coasting control based on whether or not the change value of the vehicle acceleration input from the acceleration sensor 40 is equal to or greater than a specified value. The case of changing to two steps has been described as an example. However, the coasting control ECU 100 is not limited to this, and the coasting control ECU 100 sets a plurality of specified values to be compared with the change value of the acceleration of the vehicle, and determines whether or not the coasting control can be started by comparing with each specified value. The determination period may be changed in multiple stages.

  DESCRIPTION OF SYMBOLS 10 ... Engine, 20 ... Automatic transmission, 30 ... Accelerator opening sensor, 40 ... Acceleration sensor, 50 ... Clutch mechanism, 100 ... Coasting control ECU, 101 ... Calculation part, 102 ... Memory | storage part, 103 ... Determination part, 110 ... Engine ECU, 120 ... brake ECU, 130 ... transmission ECU, X1 ... specified value.

Claims (5)

When the vehicle is coasting, the power transmission mechanism that transmits engine output to the drive wheels is switched from a connected state in which the engine output is transmitted to the drive wheels to a disconnected state in which the engine output is not transmitted to the drive wheels. A coasting control unit for executing the control,
The coasting control unit
It is determined whether or not the change value of the acceleration of the vehicle after the accelerator pedal is released is greater than or equal to a specified value. When the change value of the acceleration is equal to or greater than the specified value, the change value of the acceleration is The vehicle control device that sets a longer standby period for maintaining the coasting control not to be started from the determination time than when it is less than a specified value. The standby period is a determination period for performing a determination process for determining whether or not the coasting control can be started,
The coasting control unit
When the acceleration change value is less than the specified value, an initial value is set for the determination period, and when the acceleration change value is equal to or greater than the specified value, an additional period is added to the initial value of the determination period. The vehicle control device according to claim 1. The vehicle control device according to claim 1, wherein the coasting control unit prohibits transition to coasting control when a change value of the acceleration is equal to or greater than the specified value. The coasting control unit calculates a change value of the acceleration of the vehicle per unit time, and changes the waiting period when an average value of the change values of the vehicle acceleration in a plurality of unit times is equal to or more than the specified value. The vehicle control apparatus as described in any one of Claims 1-3. The coasting control unit stores the acceleration of the vehicle per unit time or the change value of the acceleration of the vehicle per unit time in the storage unit as acceleration information, and the elapse of the unit time after the depression of the accelerator pedal is released 5. The vehicle control device according to claim 4, wherein the acceleration information is read from the storage unit and an average value of change values in the acceleration of the vehicle over a plurality of unit times is calculated based on the read acceleration information.