Vehicle control method and vehicle control device

Abstract

To make a vehicle speed follow a target speed when sailing travel is performed during cruise control.SOLUTION: The vehicle is capable of performing cruise control for controlling a vehicle speed to a target speed set by a driver. The cruise control can perform sailing traveling in which the vehicle travels by inertia. The vehicle ends the sailing travel when a preset first deceleration cannot be obtained when the sailing travel is executed during execution of the cruise control.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a vehicle control method and a vehicle control device capable of implementing cruise control for controlling a vehicle speed to a target vehicle speed. [Background technology]

[0002] For example, Patent Document 1 discloses a technique for prohibiting accelerated coasting when the vehicle speed is increasing during coasting.

[0003] Furthermore, for example, Patent Document 2 discloses a technology in which, in a vehicle that performs cruise control to make the vehicle travel at a target vehicle speed set by the driver, if the estimated deceleration when traveling with a clutch that connects and disconnects power between the prime mover and the wheels disconnected is greater than a predetermined value, the vehicle travels with the clutch disconnected, and if the estimated deceleration is smaller than the predetermined value, the vehicle travels with the clutch connected. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-280281 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-14205 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in Patent Document 1, coasting is prohibited only when the vehicle speed increases, so coasting is not prohibited when the vehicle decelerates but the deceleration is insufficient.

[0006] Furthermore, in Patent Document 2, if it is predicted that the desired deceleration will not be obtained, the vehicle will not be driven with the clutch disengaged, and even if it is predicted that the desired deceleration will be obtained, there is a possibility that sufficient deceleration will not actually be obtained.

[0007] In other words, there is room for further improvement when coasting a vehicle in a situation where the vehicle speed is controlled to maintain a preset target speed. [Means for solving the problem]

[0008] The vehicle of the present invention is capable of implementing cruise control, which controls the vehicle speed to a predetermined target speed, and the cruise control is capable of performing sailing, which stops the vehicle's drive source when predetermined conditions are met, and releases the fastening elements provided on the power transmission path between the drive source and the drive wheels to allow the vehicle to coast, and is characterized in that if the vehicle is unable to achieve a predetermined deceleration while the sailing is being performed while the cruise control is being implemented, the sailing is terminated. [Effects of the Invention]

[0009] When the vehicle of the present invention approaches a downhill slope while sailing with cruise control in operation and the preset deceleration is not achieved and the actual vehicle speed does not approach the target speed, the sailing can be canceled (ended) to make use of engine friction torque, which allows the actual vehicle speed to approach the target speed and decelerate as desired by the driver. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is an explanatory diagram schematically illustrating a system configuration of a vehicle to which the present invention is applied; [Figure 2] 10 is a timing chart showing an example of a situation in which the target speed is changed to a lower speed during cruise control and sailing is started. [Figure 3] 10 is a timing chart showing an example of a situation in which the target speed is changed to a lower speed during cruise control and sailing is started. [Figure 4]4 is a timing chart showing an example of a situation in which sailing begins due to a torque request made by the driver while cruise control is being performed. [Figure 5] 10 is a timing chart showing an example of a situation in which sailing is terminated due to a torque request made by the driver while cruise control is being performed, and sailing is resumed after the torque request made by the driver is no longer made. DETAILED DESCRIPTION OF THE INVENTION

[0011] An embodiment of the present invention will be described in detail below with reference to the drawings.

[0012] FIG. 1 is an explanatory diagram that schematically shows the system configuration of a vehicle to which the present invention is applied.

[0013] The vehicle has an internal combustion engine 1, a torque converter 2, a clutch 3 as a coupling element, a transmission 4, drive wheels 5, and a control unit 6.

[0014] The internal combustion engine 1 is a so-called reciprocating internal combustion engine that converts the reciprocating linear motion of a piston into the rotational motion of a crankshaft and extracts the power to drive drive wheels 5, and is the drive source of the vehicle.

[0015] The torque converter 2 has a lock-up clutch (not shown) that directly connects an output shaft (internal combustion engine output shaft) 11 of the internal combustion engine 1 and an input shaft (clutch input shaft) 12 of the clutch 3.

[0016] The clutch 3 is located in the power transmission path between the internal combustion engine 1 and the drive wheels 5, and when engaged, the driving force generated in the internal combustion engine 1 can be transmitted to the transmission 4 via the transmission input shaft 13, and when released, the driving force generated in the internal combustion engine 1 is not transmitted to the transmission 4, preventing power transmission between the internal combustion engine 1 and the drive wheels 5.

[0017] The transmission 4 transmits the driving force at a changed speed to the driving wheels 5 via a final reduction gear (not shown).

[0018] The control unit 6 is a well-known digital computer equipped with a CPU, a ROM, a RAM, and an input / output interface.

[0019] The control unit 6 controls the operations of the internal combustion engine 1 , the torque converter 2 , the clutch 3 , and the transmission 4 .

[0020] The control unit 6 receives output signals from various sensors such as a crank angle sensor 15 that detects the crank angle of a crankshaft (not shown) of the internal combustion engine 1, an accelerator opening sensor 16 that detects the amount of depression of an accelerator pedal operated by the driver, a vehicle speed sensor 17 that detects the speed of the vehicle on which the internal combustion engine 1 is mounted, and a brake sensor 18 that detects the amount of depression of a brake pedal operated by the driver. The control unit 6 also receives a target speed for cruise control, which will be described later, from a target speed setting unit 21, which will be described later.

[0021] The control unit 6 controls the operations of the internal combustion engine 1, the torque converter 2, the clutch 3, and the transmission 4 based on the output signals input from the various sensors. The control unit 6 also outputs the target speed of the cruise control to a display unit 22 (described later) that displays the target speed of the cruise control.

[0022] Here, the vehicle of this embodiment is capable of implementing cruise control, which controls the vehicle speed with a target speed preset by the driver as the upper limit. Cruise control is a control unit 6 serving as a control section that controls the vehicle speed to the target speed, thereby, for example, maintaining a predetermined desired inter-vehicle distance from a vehicle ahead of the vehicle, or maintaining the vehicle speed at the target speed. Cruise control is implemented, for example, by turning on a cruise control switch (not shown) that is directly operated by the driver, and is released by turning off the switch.

[0023] During the execution of cruise control, the control unit 6 controls the internal combustion engine 1 so as to obtain a driving torque (required torque) that causes the vehicle speed to reach a target speed set by the driver.

[0024] The target speed of the vehicle in cruise control is set by the driver operating a target speed setting unit 21 that is located in a position that can be operated by the driver, such as an instrument panel inside the vehicle cabin. The target speed setting unit 21 includes, for example, an increase button (not shown) and a decrease button (not shown), and the target speed is set by operating (pressing) these buttons. For example, the target speed setting unit 21 can increase the current target speed by a predetermined speed (for example, an increase of 1 km / h) by pressing the increase button once, and can decrease the current target speed by a predetermined speed (for example, a decrease of 1 km / h) by pressing the decrease button once.

[0025] Therefore, the target speed of the vehicle in cruise control is set to a value desired by the driver by the driver tapping (pressing) the speed increase button or the speed decrease button multiple times.

[0026] The target speed of the vehicle in cruise control is displayed on a predetermined display unit 22 that is arranged in a position visible to the driver, such as an instrument panel inside the vehicle.

[0027] Furthermore, the control unit 6 automatically controls the brake 23 as an assist brake to maintain the vehicle speed and the distance from the vehicle ahead while cruise control is being implemented. The brake 23 applies braking force to the vehicle and includes, for example, a disc rotor (not shown) that rotates integrally with the wheel and brake pads (not shown) that grip the disc rotor. The control unit 6 controls the brake 23 so that the brake pads grip the disc rotor as needed while cruise control is being implemented. However, when the control unit 6 automatically controls the brake 23 as an assist brake while cruise control is being implemented, an upper limit is set for the braking force that can be applied as an assist brake. Therefore, when the control unit 6 uses the brake 23 as an assist brake, a predetermined assist upper limit braking force can be used as the upper limit. The assist upper limit braking force is set as a fail-safe and is a value smaller than the maximum braking force that can be obtained by the brake 23.

[0028] Here, if there is an opportunity to adopt coasting to keep the vehicle speed constant while cruise control is being performed, the control unit 6 performs a predetermined sailing (sailing stop). An opportunity to adopt coasting to keep the vehicle speed constant while cruise control is being performed is, for example, when a change is made to lower the target speed in cruise control while cruise control is being performed.

[0029] That is, when a sailing start condition as a predetermined condition is met while cruise control is being performed, the control unit 6 stops the internal combustion engine 1 and releases the clutch 3 to perform sailing, which allows the vehicle to coast.

[0030] Furthermore, when a predetermined sailing end condition is met while cruise control is being performed, the internal combustion engine 1 is started and the clutch 3 is engaged to enable power transmission between the internal combustion engine 1 and the drive wheels 5, thereby ending sailing.

[0031] Furthermore, when sailing while cruise control is being performed, if there is a torque request due to driving, the control unit 6 ends sailing.

[0032] The sailing start condition is, for example, that the difference between the vehicle speed (actual vehicle speed) and the vehicle target speed is equal to or greater than a first predetermined value when the driver is not depressing the vehicle's brake pedal or accelerator pedal, and that the vehicle's required torque (the driving torque) is within a range (sailing permission range) between a predetermined sailing start permission upper limit torque and a predetermined value. Here, the first predetermined value corresponds to the start speed threshold. The sailing start permission upper limit torque corresponds to the start torque threshold.

[0033] The sailing end condition is, for example, that either the difference between the actual vehicle speed and the reference speed during sailing is equal to or greater than a second predetermined value as a preset end threshold, or the actual vehicle speed is equal to or less than a sailing release vehicle speed that is a predetermined amount smaller than the target speed in cruise control.

[0034] The reference speed during sailing is determined, for example, based on a constant deceleration (sailing deceleration) calculated according to the target speed in cruise control and the vehicle speed at the start of sailing. In other words, the reference speed during sailing is the vehicle speed obtained by decelerating the vehicle speed at the start of sailing at the sailing deceleration, and decreases at a constant slope (sailing deceleration) until the target speed is reached. In other words, the reference speed is obtained by decelerating the vehicle at the sailing deceleration starting from the target speed in cruise control before the change.

[0035] The sailing deceleration is set to a larger value as the difference between the target speed in cruise control and the vehicle speed at the start of sailing, i.e., the difference between the target speed in the changed cruise control and the target speed in the previous cruise control, increases. In other words, the slope of the reference speed increases as the difference between the target speed in cruise control and the vehicle speed at the start of sailing increases.

[0036] For the above reasons, when sailing is being performed while cruise control is being implemented, if the sailing deceleration, which is the constant deceleration set at the start of sailing, is not obtained, the control unit 6 will end sailing.

[0037] When the difference between the actual speed of the vehicle and the reference speed becomes equal to or greater than the second predetermined value during sailing while cruise control is being performed, the control unit 6 ends sailing.

[0038] FIG. 2 is a timing chart showing an example of a situation in which the target speed is changed to a lower speed during cruise control and sailing is started.

[0039] In FIG. 2, the characteristic line indicated by the thick solid line Sr is the actual vehicle speed, the characteristic line indicated by the thick dashed line Ss is the reference speed, and the characteristic line indicated by the solid line St is the target speed in cruise control.

[0040] In Fig. 2, cruise control is performed from time t0 to time t6 onwards. That is, in Fig. 2, the cruise control state is a cruising state from time t0 to time t6 onwards.

[0041] Time t1 in FIG. 2 is the timing when the target speed in cruise control is changed by the driver to a lower speed.

[0042] The timing of time t2 in Figure 2 is the timing when the sailing obstruction factor (CCSL_internal) due to the vehicle speed request disappears. The sailing obstruction factor (CCSL_internal) due to the vehicle speed request occurs, for example, when the difference between the actual vehicle speed and the target speed is equal to or greater than the first predetermined value.

[0043] At time t3 in FIG. 2, the clutch 3 is released, the internal combustion engine 1 is stopped, and sailing begins.

[0044] In Figure 2, time t3 is the timing when a predetermined time has elapsed since the torque required by cruise control falls below the sailing start permission upper limit torque. In Figure 2, the sailing state switches from non-sailing to sailing at the timing when a predetermined time has elapsed since the torque required by cruise control falls within the sailing permission range.

[0045] 2, the sailing obstruction factor (CCSL_output) switches from present to absent at time t3. For example, if the state in which there are no obstructions in the sailing obstruction factor (CCSL_internal) and the sailing obstruction factor (PTM) continues for a predetermined time, the sailing obstruction factor (CCSL_output) determines that there are no obstructions to transitioning to sailing.

[0046] The sailing obstruction factor (PTM) is a factor obstructing sailing from the torque request perspective, which assumes that there is no factor obstructing sailing if the difference between the actual torque of the cruise control and the requested torque is within a predetermined amount, for example.

[0047] That is, in FIG. 2, at time t3, the sailing obstruction factor (CCSL_output) switches from present to absent, and the sailing state switches from non-sailing to sailing, so sailing begins at this time t3.

[0048] At time t4 in Fig. 2, the actual vehicle speed becomes equal to or lower than the sailing release vehicle speed, and the sailing obstruction factor (CCSL_internal) and the sailing obstruction factor (CCSL_output) change from absent to present. The control unit 6 starts the internal combustion engine 1 at time t4 in Fig. 2, and ends sailing at this time t4.

[0049] Time t5 in Figure 2 is the timing when a predetermined time has elapsed since time t4 in Figure 2, and is the timing to engage the clutch 3. In Figure 2, at time t5, the sailing state switches from sailing to non-sailing.

[0050] At time t6 in Fig. 2, the driver changes the target speed in cruise control to a lower speed. However, because the difference between the target speed and the actual vehicle speed this time is less than the first predetermined value, the control unit 6 does not perform sailing travel in response to the change in target speed at time t6 in Fig. 2.

[0051] Fig. 3 is a timing chart showing an example of a situation in which the target speed is changed to a lower value during cruise control and sailing begins. Fig. 3 shows an example of the behavior of a vehicle while cruise control is being performed on a downhill slope. Fig. 3 shows a case in which the required deceleration is not obtained during sailing, and sailing ends before the vehicle speed reaches the target speed.

[0052] In FIG. 3, the characteristic line indicated by the thick solid line Sr is the actual vehicle speed, the characteristic line indicated by the thick dashed line Ss is the reference speed, and the characteristic line indicated by the solid line St is the target speed in cruise control.

[0053] In Fig. 3, cruise control is performed from time t0 to time t4 onwards. That is, in Fig. 3, the cruise control state is in a cruising state from time t0 to time t4 onwards. Also, in Fig. 3, since the vehicle is traveling downhill, in order to control the vehicle speed to the target speed in cruise control, the control unit 6 controls the brake 23 as an assist brake, thereby controlling the required torque during sailing.

[0054] At time t1 in FIG. 3, the target speed in cruise control is changed to a lower speed by the driver while the vehicle is sailing.

[0055] Time t2 in Figure 3 is the time when the braking force of the assist brake reaches the assist upper limit braking force. After time t2 in Figure 3, the braking force from the assist brake alone is insufficient, and the vehicle enters a region where it is no longer possible to make the vehicle speed follow the reference speed, and therefore the target speed in cruise control. Therefore, due to the insufficient braking force, the deceleration of the actual vehicle speed decreases from time t2 in Figure 3, and the actual vehicle speed begins to deviate from the reference speed during sailing.

[0056] Time t3 in Figure 3 is the timing when the difference between the actual vehicle speed and the reference speed during sailing becomes equal to or greater than the second predetermined value. In Figure 3, at time t3, the sailing obstruction factor (CCSL_internal) due to the vehicle speed request switches from absent to present, and the sailing obstruction factor (CCSL_output) switches from absent to present. The control unit 6 ends sailing at time t3 in Figure 3.

[0057] Time t4 in Figure 3 is the timing when engagement of the clutch 3 is completed. From time t4 in Figure 3, the friction torque (engine brake) of the internal combustion engine 1 is used in addition to the assist upper limit braking force of the assist brake to make the actual vehicle speed follow the target speed in cruise control. The decrease in the required torque from time t4 in Figure 3 is due to the friction torque of the internal combustion engine 1. In Figure 3, at time t4, the sailing state switches from sailing to non-sailing.

[0058] FIG. 4 is a timing chart showing an example of a situation in which sailing begins due to a torque request made by the driver while cruise control is being performed.

[0059] In FIG. 4, before time t1, the boat is sailing while cruise control is being performed.

[0060] In FIG. 4, the characteristic line indicated by the thick solid line Sr is the actual vehicle speed, the characteristic line indicated by the thick dashed line Ss is the reference speed, and the characteristic line indicated by the solid line St is the target speed in cruise control.

[0061] In Figure 4, the characteristic line indicated by the thick solid line Tc is the torque required by cruise control, and the characteristic line indicated by the thick dashed line Td is the torque required by the driver, for example, by depressing the accelerator pedal.

[0062] Time t1 in Figure 4 is the timing when driver-requested torque occurs during sailing. The cruise control state switches from a cruising state to a non-cruising state at time t1 in Figure 4. When driver-requested torque occurs, the sailing obstruction factor (PTM) switches from absent to present. The control unit 6 starts the internal combustion engine 1 at time t1 in Figure 4.

[0063] At time t2 in FIG. 4, the vehicle speed becomes greater than the target speed in cruise control.

[0064] Time t3 in FIG. 4 is the timing when the driver requested torque becomes "0." The cruise control state switches from the non-cruise state to the cruise state at time t3 in FIG. 4. The period from time t1 to t3 when the cruise control state is non-cruise is an override period in which the driver request takes precedence over the cruise control. In other words, if a driver operation (driving request) occurs while cruise control is being performed, the driver's operation takes priority, and cruise control resumes when the driver's operation ends. Internally, control unit 6 does not terminate cruise control during the override period from time t1 to t3 in FIG. 4, but continues it.

[0065] The timing of time t4 in Fig. 4 is the timing to stop the internal combustion engine 1 and start sailing. Because the difference between the actual vehicle speed and the target speed in cruise control becomes equal to or greater than the first predetermined value due to the driver's request from time t1 to time t3 in Fig. 4, the control unit 6 resumes sailing from the timing of time t4 in Fig. 4.

[0066] At time t5 in FIG. 4, the driver-requested torque occurs again during sailing. The cruise control state switches from the cruising state to the non-cruising state at time t5 in FIG. 4. When the driver-requested torque occurs, the sailing obstruction factor (PTM) switches from absent to present. The control unit 6 starts the internal combustion engine 1 at time t5 in FIG. 4.

[0067] At time t6 in FIG. 4, the vehicle speed becomes greater than the target speed in cruise control.

[0068] At time t7 in FIG. 4, the driver requested torque becomes "0." Also, at time t7, the sailing obstruction factor (PTM) switches from present to absent, and the sailing obstruction factor (CCSL_output) switches from absent to present. The cruise control state switches from a non-cruise state to a cruise state at time t7 in FIG. 4. The period from time t5 to t7 when the cruise control state is non-cruise is an override period in which the driver's request takes precedence over the cruise control, similar to the period from time t1 to t3 in FIG. 4. Internally, the control unit 6 does not terminate the cruise control during the override period from time t5 to t7 in FIG. 4, but continues it.

[0069] However, because the driver-requested torque during the override period from time t5 to time t7 in Figure 4 was relatively small, the difference between the vehicle speed and the target speed in cruise control at time t7 in Figure 4 was not greater than the first predetermined value. Furthermore, the requested torque in cruise control was also negative. Therefore, the control unit 6 did not perform sailing after time t7 in Figure 4.

[0070] Fig. 5 is a timing chart showing an example of a situation in which sailing is terminated due to a torque request by the driver while cruise control is in operation, and then resumed after the torque request by the driver is removed. Fig. 5 shows a case in which the required deceleration is not obtained during the resumed sailing, and sailing is terminated before the vehicle speed reaches the target speed.

[0071] In FIG. 5, before time t1, the boat is sailing while cruise control is being performed.

[0072] In FIG. 5, the characteristic line indicated by the thick solid line Sr is the actual vehicle speed, the characteristic line indicated by the thick dashed line Ss is the reference speed, and the characteristic line indicated by the solid line St is the target speed in cruise control.

[0073] In Figure 5, the characteristic line indicated by the thick solid line Tc is the torque required by cruise control, and the characteristic line indicated by the thick dashed line Td is the torque required by the driver, for example, by depressing the accelerator pedal.

[0074] Time t1 in Figure 5 is the timing when driver-requested torque occurs during sailing. The cruise control state switches from a cruising state to a non-cruising state at time t1 in Figure 5. When driver-requested torque occurs, the sailing obstruction factor (PTM) switches from absent to present. The control unit 6 starts the internal combustion engine 1 at time t1 in Figure 5.

[0075] At time t2 in FIG. 5, the vehicle speed becomes greater than the target speed in cruise control.

[0076] At time t3 in FIG. 5, the driver requested torque becomes "0." Also, at time t3 in FIG. 5, the sailing obstruction factor (PTM) switches from present to absent. At time t3 in FIG. 5, the cruise control state switches from the non-cruise state to the cruise state. The period from time t1 to t3, during which the cruise control state is non-cruise, is an override period in which the driver's request takes precedence over the cruise control. In other words, if a driver's operation (driving request) occurs while cruise control is being performed, the driver's operation takes precedence, and cruise control resumes when the driver's operation ends. Internally, the control unit 6 does not terminate cruise control during the override period from time t1 to t3 in FIG. 5, but continues it.

[0077] The timing of time t4 in Fig. 5 is the timing to stop the internal combustion engine 1 and start sailing. Because the difference between the actual vehicle speed and the target speed in cruise control becomes equal to or greater than the first predetermined value due to the driver's request from time t1 to time t3 in Fig. 5, the control unit 6 resumes sailing from the timing of time t4 in Fig. 5.

[0078] Time t5 in Figure 5 is the time when the braking force of the assist brake reaches the assist upper limit braking force. After time t5 in Figure 5, the braking force from the assist brake alone is insufficient, and the vehicle speed reaches a region where it cannot track the reference speed, and therefore the target speed in cruise control. Therefore, in Figure 5, the actual vehicle speed begins to increase from time t5 due to insufficient braking force, and deviates from the reference speed during sailing.

[0079] Time t6 in Figure 5 is the timing when the difference between the actual vehicle speed and the reference speed during sailing becomes equal to or greater than the second predetermined value. In Figure 5, at time t6, the sailing obstruction factor (CCSL_internal) due to the vehicle speed request switches from absent to present, and the sailing obstruction factor (CCSL_output) switches from absent to present. The control unit 6 ends sailing at time t6 in Figure 5.

[0080] Time t7 in Figure 5 is the timing when engagement of the clutch 3 is completed. From time t7 in Figure 5, the friction torque (engine brake) of the internal combustion engine 1 is used in addition to the assist upper limit braking force of the assist brake to make the actual vehicle speed follow the target speed in cruise control. The decrease in the required torque from time t7 in Figure 5 is due to the friction torque of the internal combustion engine 1. In Figure 5, at time t7, the sailing state switches from sailing to non-sailing.

[0081] The timing of time t8 in FIG. 5 is the timing when the sailing obstruction factor (PTM) switches from absent to present.

[0082] In the vehicle of the above-described embodiment, when the vehicle approaches a downhill slope while sailing with cruise control in operation and the preset deceleration is not achieved and the actual vehicle speed does not approach the target speed, the sailing can be canceled (ended) to use the engine friction torque. This allows the actual vehicle speed to approach the target speed, and the vehicle can decelerate as desired by the driver.

[0083] Furthermore, when sailing while cruise control is in operation, if the deceleration during sailing is in line with the pre-set deceleration, sailing will not be cancelled (ended) and will be maintained, thereby increasing the number of situations in which sailing is permitted as much as possible, and improving fuel efficiency overall.

[0084] Although specific embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the invention.

[0085] For example, the vehicle may be a parallel hybrid vehicle having an internal combustion engine and an electric motor as drive sources.

[0086] The above-described embodiments relate to a vehicle control method and a vehicle control device. [Explanation of symbols]

[0087] 1...Internal combustion engine 2...Torque converter 3...Clutch 4...Gearbox 5...Drive wheels 6...Control unit 11...Output shaft 12...Input shaft 13...Transmission input shaft 15...Crank angle sensor 16...Accelerator opening sensor 17...Vehicle speed sensor 18...Brake sensor 21…Target speed setting section 22...Display section 23...Brake

Claims

1. A method for controlling a vehicle capable of performing cruise control to control a vehicle speed to a predetermined target speed, The cruise control is capable of performing sailing travel by stopping the drive source of the vehicle when a predetermined condition is met and releasing a fastening element provided on a power transmission path between the drive source and the drive wheels to allow the vehicle to travel by inertia, A vehicle control method characterized in that, when the sailing is being performed while the cruise control is being performed, if the vehicle does not achieve a preset deceleration, the sailing is terminated.

2. A vehicle control method as described in claim 1, characterized in that a reference speed at which the vehicle decelerates at the deceleration rate is set, and the sailing is terminated when the difference between the actual vehicle speed and the reference speed becomes equal to or greater than a termination threshold during the sailing while the cruise control is being performed.

3. 3. The vehicle control method according to claim 2, wherein when the sailing is performed after changing the target speed in the cruise control to a lower speed, the reference speed is obtained by decelerating the vehicle at the deceleration rate starting from the target speed before the change.

4. 4. The vehicle control method according to claim 3, wherein, when the sailing is being performed while the cruise control is being performed, the sailing is terminated when the actual vehicle speed falls below a predetermined sailing cancellation vehicle speed which is lower than the target speed in the cruise control.

5. 5. The vehicle control method according to claim 4, wherein sailing is not initiated when the difference between the target speed and the actual vehicle speed in the cruise control is smaller than a start speed threshold.

6. The condition for starting the sailing while the cruise control is being performed includes a required torque being equal to or less than a start torque threshold, 6. A vehicle control method as described in claim 5, wherein even if the required torque is equal to or less than the start torque threshold while the cruise control is being performed, if the difference between the target speed and the actual vehicle speed in the cruise control is smaller than the start speed threshold, sailing is not started.

7. a control unit capable of performing cruise control to control the vehicle speed to a predetermined target speed; The cruise control is capable of performing sailing travel by stopping the drive source of the vehicle when a predetermined condition is met and releasing a fastening element provided on a power transmission path between the drive source and the drive wheels to allow the vehicle to travel by inertia, The control unit of the vehicle control device is characterized in that, when the sailing is being performed while the cruise control is being implemented, if the vehicle does not achieve a preset sailing deceleration, the control unit terminates the sailing.

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