Vehicle control device

Abstract

To enhance drivability during travel control.SOLUTION: There is provided a control device 10 of a vehicle VH, the vehicle VH comprising a gear shifter 23 on power transmission path which transmits power from a driving device 20 to driving wheels. The control device comprises: a travel control unit 100 which sets target acceleration Gt of the vehicle VH on the basis of either of target vehicle speed Vt and actual vehicle speed V or target inter-vehicle distance Dt and actual inter-vehicle distance D, and executes travel control which operates the driving device 20 on the basis of the target acceleration Gt; a speed change control unit 110 which sets target driving force Ft on the basis of at least the actual vehicle speed V and executes speed change control which operates the gear shifter 23 on the basis of the target driving force Ft; and a down-shift restraint control unit 120 which acquires actual acceleration G during execution of the travel control by the travel control unit 100 and restrains down-shift by the speed change control unit 110 from executing, on the basis of prescribed acceleration threshold value Ga different from the target acceleration Gt and the actual acceleration G.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a control device for a vehicle. [Background technology]

[0002] Patent document 1 discloses a device that limits the acceleration of a vehicle by suppressing downshifting of the transmission when a predetermined condition is met in which a following vehicle traveling in an adjacent lane attempts to overtake the vehicle while adaptive cruise control (ACC) is being performed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6989704 Summary of the Invention

[0004] During manual driving, where the driver operates the accelerator pedal while driving the vehicle, there are situations where the actual acceleration of the vehicle is insufficient compared to the driver's intention. Even in such a situation, if the insufficiency of the actual acceleration is within the driver's tolerance, the driver may maintain the accelerator pedal depression and wait for the actual acceleration to increase, thereby driving the vehicle so that the transmission does not automatically downshift (kick down).

[0005] On the other hand, in cruise control (hereinafter simply referred to as driving control) such as ACC, the operation of the drivetrain is, for example, feedback-controlled based on the deviation between the target vehicle speed and the actual vehicle speed. Therefore, in a situation where the actual vehicle speed is insufficient for the target vehicle speed while cruise control is being executed, even if the actual acceleration is within the driver's tolerance range, the output of the drivetrain is increased so that the actual vehicle speed approaches the target vehicle speed, resulting in the transmission being downshifted. Such situations are likely to occur when traveling on an uphill road with a relatively steep gradient, when re-accelerating after the end of speed management control that decelerates on a curved road, when the preceding vehicle accelerates while following the preceding vehicle at a speed slower than the target vehicle speed, etc.

[0006] If the transmission downshifts due to acceleration that the driver perceives as unnecessary during cruise control, a gear shock occurs in a stepped transmission, or a sudden increase in the rotation speed of the drive unit occurs in a continuously variable transmission, resulting in problems such as a deterioration in drivability. The device described in Patent Document 1 applies the ACC acceleration limit to situations such as when a following vehicle is attempting to overtake the vehicle, but does not anticipate application to situations where the actual vehicle speed is insufficient compared to the target vehicle speed, such as when traveling uphill. For this reason, it can be said that the above-mentioned problems can occur even with the device described in Patent Document 1.

[0007] The present disclosure aims to effectively improve drivability during cruise control.

[0008] The device disclosed herein is a control device for a vehicle equipped with a transmission device in a power transmission path that transmits power from a drive device to a drive wheel, and includes a driving control unit that sets a target acceleration of the vehicle based on either a predetermined target vehicle speed and an actual vehicle speed, or a predetermined target vehicle-to-vehicle distance and an actual vehicle-to-vehicle distance, and performs driving control that automatically controls the driving of the vehicle by operating the drive device based on the target acceleration; a gear change control unit that sets a target driving force of the vehicle based on at least the actual vehicle speed, and performs gear change control that operates the transmission based on the target driving force; and a shift down suppression control unit that acquires the actual acceleration while the driving control unit is performing the driving control, and suppresses the gear change control unit from downshifting the transmission based on the actual acceleration and a predetermined acceleration threshold value that is different from the target acceleration. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing a hardware configuration of a vehicle according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram showing a software configuration of the control device according to the present embodiment. [Figure 3] FIG. 4 is a schematic diagram illustrating an allowable acceleration map. [Figure 4] 5 is a timing chart illustrating the shift-down suppression control. [Figure 5] 4 is a flowchart illustrating a routine for shift-down suppression control. [Figure 6] 10 is a timing chart illustrating a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, a vehicle control device according to this embodiment will be described with reference to the drawings.

[0011] [Hardware configuration] 1 is a schematic diagram showing the hardware configuration of a vehicle VH according to this embodiment. Hereinafter, the vehicle VH may also be referred to as the host vehicle when it is necessary to distinguish it from other vehicles.

[0012] The vehicle VH has an ECU (Electronic Control Unit) 10. The ECU 10 includes a CPU (Central Processing Unit) 11, a ROM (Read Only Memory) 12, a RAM (Random Access Memory) 13, and an interface device 14. The CPU 11 is a processor that executes various programs stored in the ROM 12. The ROM 12 is a non-volatile memory that stores data and the like required for the CPU 11 to execute the various programs. The RAM 13 is a volatile memory that provides a working area into which the various programs are expanded when the CPU 11 executes them. The interface device 14 is a communication device for communicating with external devices.

[0013] The ECU 10 is a central device that performs various controls such as ACC, gear change control, etc. The ECU 10 is communicably connected to a drive unit 20, a steering unit 21, a braking unit 22, a gear change unit 23, an internal sensor unit 30, an external sensor unit 40, an ACC operation unit 50, etc.

[0014] The drive unit 20 generates power to be transmitted to the drive wheels of the vehicle VH. Examples of the drive unit 20 include an electric motor and an engine. The vehicle VH may be any of an internal combustion engine vehicle, a hybrid vehicle (HEV), a plug-in hybrid vehicle (PHEV), a fuel cell vehicle (FCEV), and an electric vehicle (BEV), as long as the vehicle is equipped with a transmission 23 in a power transmission path between the drive unit 20 and the drive wheels (not shown). The steering unit 21 applies a steering force to the wheels of the vehicle VH. The braking unit 22 applies a braking force to the wheels of the vehicle VH. The transmission 23 is, for example, a stepped transmission, which changes the speed of the rotational power output from the drive unit 20 at a predetermined gear ratio and transmits it to the drive wheels. Note that the transmission 23 may be a continuously variable transmission, but the following description will be given assuming that the transmission 23 is a stepped transmission.

[0015] The internal sensor device 30 is a group of sensors that detect the state of the vehicle VH. Specifically, the internal sensor device 30 includes a wheel speed sensor 31, an accelerator sensor 32, a brake sensor 33, a yaw rate sensor 34, a shift sensor 35, and the like.

[0016] The wheel speed sensor 31 detects the traveling speed of the vehicle VH, i.e., the actual vehicle speed V. The accelerator sensor 32 detects the amount of operation of an accelerator pedal (not shown) by the driver, i.e., the accelerator opening degree Ac. The brake sensor 33 detects the amount of operation of a brake pedal (not shown) by the driver. The yaw rate sensor 34 detects the yaw rate of the vehicle VH. The shift sensor 35 detects the shift position SP (parking P, reverse R, neutral N, drive D) of the transmission 23. The internal sensor device 30 transmits the state of the vehicle VH detected by each of the sensors 31 to 35 to the ECU 10 at a predetermined interval.

[0017] The external sensor device 40 is a type of sensor that recognizes target information related to targets around the vehicle VH. Specifically, the external sensor device 40 includes a radar sensor 41, a camera sensor 42, etc. Examples of target information include nearby vehicles, pedestrians, traffic lights, white lines on the road, signs, fallen objects, etc.

[0018] The radar sensor 41 detects targets present in the area ahead of the vehicle VH. The radar sensor 41 includes a millimeter-wave radar and / or a lidar. The millimeter-wave radar emits millimeter-wave radio waves (millimeter waves) and receives millimeter waves (reflected waves) reflected by targets present within the emission range. The millimeter-wave radar acquires the relative distance and relative speed between the vehicle VH and the target based on the phase difference between the transmitted millimeter waves and the received reflected waves, the attenuation level of the reflected waves, and the time between transmitting the millimeter waves and receiving the reflected waves. The lidar sequentially scans a pulsed laser beam with a wavelength shorter than that of millimeter waves in multiple directions and receives the reflected light reflected by the target to acquire the shape of the target detected ahead of the vehicle VH, the relative distance and relative speed between the vehicle VH and the target, etc.

[0019] The camera sensor 42 is, for example, a stereo camera or a monocular camera, and a digital camera having an imaging element such as a CMOS or CCD can be used. The camera sensor 42 captures an image of the area ahead of the vehicle VH and processes the captured image data to acquire target information ahead of the vehicle VH. The target information is information that indicates the type of target detected ahead of the vehicle VH, the relative distance between the vehicle VH and the target, the relative speed between the vehicle VH and the target, etc. The type of target may be recognized, for example, by machine learning such as pattern matching.

[0020] The external sensor device 40 repeatedly transmits the acquired target information to the ECU 10 every time a predetermined time period has elapsed. The ECU 10 determines the relative relationship between the vehicle VH and the target by combining the relative relationship between the vehicle VH and the target obtained by the radar sensor 41 and the relative relationship between the vehicle VH and the target obtained by the camera sensor 42. Note that the external sensor device 40 does not necessarily have to include both the radar sensor 41 and the camera sensor 42, and may include, for example, only the radar sensor 41 or only the camera sensor 42.

[0021] The ACC operation unit 50 is provided near the driver's seat (for example, on the steering wheel, steering column, etc.) and is a group of switches operated by the driver. The ACC operation unit 50 includes, for example, a start switch 51 for selecting whether to start or end the ACC, a setting switch 52 for setting the ACC target vehicle speed Vt and target inter-vehicle distance Dt (target inter-vehicle time), a cancel switch 53 for temporarily canceling an active ACC, and a resume switch 54 for resuming the ACC. Note that some of these switches (for example, the cancel switch 53 and the resume switch 54) may be integrated into a single switch.

[0022] [Software configuration] Fig. 2 is a schematic diagram showing the software configuration of the ECU 10 according to this embodiment. As shown in Fig. 2, the ECU 10 includes, as functional elements, an ACC control unit 100, a transmission control unit 110, a downshift suppression control unit 120, and the like. These functional elements 100 to 120 are realized by the CPU 11 of the ECU 10 reading out a program stored in the ROM 12 into the RAM 13 and executing the program. Note that all or part of the functional elements 100 to 120 may be provided in another ECU separate from the ECU 10, or in an information processing device in a facility (such as a management center) that can communicate with the vehicle VH.

[0023] The ACC control unit 100 executes ACC based on the target vehicle speed Vt or the target inter-vehicle distance Dt. ACC itself is well known, so it will be briefly explained below. ACC includes two types of control: constant speed cruise control and follow-up cruise control. Constant speed cruise control is control that causes the vehicle VH to cruise at a constant speed according to the target vehicle speed Vt without the driver needing to operate the accelerator or brake. Follow-up cruise control is control that causes the host vehicle VH to follow the preceding vehicle so that the actual inter-vehicle distance D between the preceding vehicle and the host vehicle VH becomes the target inter-vehicle distance Dt without the driver needing to operate the accelerator or brake. The preceding vehicle is a vehicle that is traveling in the area ahead of the host vehicle VH and immediately before the host vehicle VH.

[0024] When the ACC start switch 51 is turned ON, the ACC control unit 100 determines whether or not there is a preceding vehicle to be followed based on the detection results of the external sensor device 40. If the ACC control unit 100 determines that there is no preceding vehicle, it executes constant-speed cruise control. In this case, the ACC control unit 100 calculates a target acceleration Gt from the deviation between the actual vehicle speed V and the target vehicle speed Vt, and controls the operation of the drive unit 20 and the brake unit 22 based on the calculated target acceleration Gt. The actual vehicle speed V may be obtained based on the detection results of the wheel speed sensor 31. On the other hand, if the ACC control unit 100 determines that there is a preceding vehicle, it executes follow-up cruise control. In this case, the ACC control unit 100 calculates a target acceleration Gt from the deviation between the actual inter-vehicle distance D and the target inter-vehicle distance Dt, and controls the operation of the drive unit 20 and the brake unit 22 based on the calculated target acceleration Gt. The actual inter-vehicle distance D between the host vehicle VH and the preceding vehicle may be obtained based on the detection results of the external sensor device 40.

[0025] When the vehicle VH travels on a curved road while the ACC is running, the ACC control unit 100 performs so-called speed management control, which controls the actual vehicle speed V of the vehicle VH by adjusting the acceleration of the vehicle VH so that the vehicle VH can travel stably on the curved road. Whether the vehicle VH is traveling on a curved road may be determined based on lane marking information, such as white lines, acquired by the external sensor device 40, or based on the detection results of the yaw rate sensor 34. If the vehicle VH has a map database storing map information, whether the vehicle VH is traveling on a curved road may be determined based on the current position of the vehicle VH acquired by a GPS or other device and the map information. The amount of acceleration adjustment may be set based on, for example, the curvature of the curved road on which the vehicle VH is traveling. The curvature of the curved road may be acquired based on the detection results of the external sensor device 40, or, if the vehicle VH has a map database, may be acquired based on the map information. The ACC control unit 100 terminates speed management control when the vehicle VH has finished traveling on the curved road.

[0026] The gear shift control unit 110 executes gear shift control to automatically upshift or downshift the transmission 23 based on the driving conditions of the vehicle VH, etc. The gear shift control is executed, for example, by referring to a shift map (not shown) based on the target driving force Ft of the vehicle VH, which corresponds to the current actual vehicle speed V and the required acceleration. Specifically, during manual driving in which the driver drives the vehicle VH while operating the accelerator pedal, the gear shift control unit 110 sequentially calculates the target driving force Ft of the vehicle VH based on the current actual vehicle speed V of the vehicle VH and the driver-requested acceleration Gd, which corresponds to the accelerator pedal opening Ac. Here, manual driving includes not only cases where the ACC start switch 51 is OFF, but also cases where the driver overrides the ACC by operating the accelerator even when the ACC start switch 51 is ON, or cases where the ACC is temporarily released by turning on the cancel switch 53 or operating the brakes. The actual vehicle speed V may be obtained based on the detection results of the wheel speed sensor 31, and the accelerator pedal opening Ac may be obtained based on the detection results of the accelerator sensor 32. In addition, during driving assistance driving in which the vehicle VH is traveling using ACC, the gear shift control unit 110 sequentially calculates the target driving force Ft of the vehicle VH based on the current actual vehicle speed V of the vehicle VH and the target acceleration Gt of the ACC calculated by the ACC control unit 100.

[0027] When the sequentially calculated target driving force Ft exceeds the upshift line on the shift map from the nth gear side (where n is an integer) to the n+1th gear side, the transmission control unit 110 sends an upshift command to the transmission 23. This causes the transmission 23 to automatically upshift from the current gear to the next higher gear. On the other hand, when the target driving force Ft exceeds the downshift line on the shift map from the n+1th gear side to the nth gear side, the transmission control unit 110 sends a downshift command to the transmission 23. This causes the transmission 23 to automatically downshift from the current gear to the next lower gear. The downshift line is an example of a driving force threshold value of the present disclosure.

[0028] [Comparative Example] Here, a comparative example will be described with reference to Fig. 6 in which the downshift suppression control, which will be described later, is not executed in a situation where the actual vehicle speed V is insufficient for the target vehicle speed Vt while the ACC is being executed. Situations in which the actual vehicle speed V is insufficient for the ACC target vehicle speed Vt include, for example, (1) when the vehicle is traveling on a road with a relatively steep gradient, (2) when the vehicle re-accelerates after the speed management control ends, and (3) when the host vehicle decelerates in response to the deceleration of the preceding vehicle while following the preceding vehicle, and then re-accelerates due to the preceding vehicle re-accelerating. Fig. 6 is a timing chart of a comparative example showing the time changes in vehicle speed, acceleration, target driving force, and gear position in such situations.

[0029] As shown in Figure 6, from time t0 to time t1, the actual vehicle speed V of the vehicle gradually decreases relative to the target vehicle speed Vt of the ACC. In this case, the actual acceleration G of the vehicle also gradually decreases relative to the target acceleration Gt of the ACC, and the deviation between them increases. As the actual acceleration G decreases relative to the target acceleration Gt, the target driving force Ft of the vehicle gradually increases.

[0030] At time t2, the target driving force Ft reaches the downshift line LD on the shift map and crosses the downshift line DL from the n+1 gear side to the n gear side. In this case, even if the actual acceleration G at time t2 is within the driver's tolerance range (for example, a range in which the driver does not feel the need for further acceleration, and is equal to or greater than the allowable acceleration Ga described below), a downshift from the n+1 gear to the n gear is executed. After time t2, the deviation of the actual acceleration G from the target acceleration Gt becomes smaller due to the downshift, and as the target driving force Ft decreases, at time t4, the target driving force Ft reaches the upshift line LU on the shift map, and an upshift from the n gear to the n+1 gear is executed.

[0031] In the comparative example shown in FIG. 6, a downshift is performed at time t2, causing a shift shock (jerk, jerk) in which the actual acceleration G fluctuates significantly from time t2 to time t3. That is, even if the actual acceleration G is within the driver's tolerance range, an unnecessary downshift causes a shift shock, resulting in a deterioration in drivability. Such a deterioration in drivability can occur even if the transmission is a continuously variable transmission due to a sudden increase in the output rotation speed of the drive unit. Another problem is that an unnecessary downshift increases the mechanical load on the transmission 23.

[0032] [Shift-down suppression control] The downshift suppression control unit 120 of this embodiment prevents deterioration of drivability during ACC by suppressing the execution of downshifts that the driver feels are unnecessary. Specifically, the downshift suppression control unit 120 sequentially determines whether the actual acceleration Gt of the vehicle VH is equal to or greater than a predetermined allowable acceleration Ga while the vehicle VH is traveling under ACC. The actual acceleration Gt may be obtained by differentiating the detection value of the wheel speed sensor 31, or, if the vehicle VH is equipped with an acceleration sensor, may be obtained based on the detection result of the acceleration sensor. The allowable acceleration Ga is an example of an acceleration threshold value in the present disclosure.

[0033] FIG. 3 is a schematic diagram illustrating an allowable acceleration map M that defines the relationship between the allowable acceleration Ga and the actual vehicle speed V. The horizontal axis of the allowable acceleration map M represents the actual vehicle speed, and the vertical axis represents the acceleration. Note that the vertical and horizontal axes can be interchanged. The allowable acceleration map M is pre-stored in, for example, a ROM of the ECU 10. The allowable acceleration Ga is set to decrease as the actual vehicle speed increases. The allowable acceleration Ga is set to an acceleration that is smaller than the ACC target acceleration Gt and larger than the value at which the driver can feel the acceleration of the vehicle VH (see dashed line L). Specifically, the allowable acceleration Ga is set based on an acceleration at which kickdown of the transmission 23 is not required during manual driving in which the driver drives the vehicle VH while operating the accelerator, i.e., an acceleration at which the driver can maintain the accelerator operation amount and wait for the actual vehicle speed V to increase. The allowable acceleration Ga may be set in advance by simulation or the like, or may be set by acquiring and reflecting information on the acceleration used by many drivers from big data or the like.

[0034] When the vehicle VH travels using the ACC, the downshift suppression control unit 120 sequentially acquires the permissible acceleration Ga corresponding to the actual vehicle speed V by referring to the permissible acceleration map M based on the actual vehicle speed V at that time. Upon acquiring the permissible acceleration Ga, the downshift suppression control unit 120 determines whether the actual acceleration G of the vehicle VH at that time is equal to or greater than the permissible acceleration Ga. If the actual acceleration G is equal to or greater than the permissible acceleration Ga, the downshift suppression control unit 120 suppresses the execution of a downshift by the transmission control unit 110, i.e., prohibits a downshift, even if a downshift condition is met in which the target driving force Ft exceeds the downshift line DL on the shift map.

[0035] This suppresses unnecessary downshifts that the driver does not want while the ACC is running. As a result, it is possible to prevent the occurrence of gear shift shocks associated with downshifts, thereby improving drivability. It is also possible to adjust the ACC target acceleration based on road gradient information, etc., but in this case, it is necessary to sequentially calculate an appropriate ACC target acceleration that does not cause the transmission 23 to downshift. This not only increases the number of steps required for adaptation but also requires a device to acquire gradient information, resulting in increased costs. In contrast, this embodiment, which suppresses downshifts based on the allowable acceleration Ga, significantly reduces the number of steps required for adaptation. Furthermore, since a device to acquire gradient information is not required, it is possible to effectively suppress costs. Furthermore, by suppressing unnecessary downshifts, it is possible to effectively reduce the mechanical load on the transmission 23.

[0036] Fig. 4 is a timing chart illustrating the shift-down suppression control according to this embodiment. Similar to the comparative example in Fig. 6, Fig. 4 is a timing chart showing the time variations of the vehicle speed, acceleration, target driving force, and gear position in the above-mentioned scenarios (1) to (3) where the actual vehicle speed V is insufficient relative to the target vehicle speed Vt while the ACC is being executed.

[0037] As shown in Fig. 4, from time t0 to time t1, the actual vehicle speed V of the vehicle VH gradually decreases relative to the target vehicle speed Vt of the ACC. In this case, the actual acceleration G of the vehicle VH also gradually decreases relative to the target acceleration Gt of the ACC. As the actual acceleration G decreases relative to the target acceleration Gt, the target driving force Ft of the vehicle VH gradually increases.

[0038] Assume that at time t1, actual acceleration G exceeds allowable acceleration Ga, and at time t2, target driving force Ft reaches downshift line LD on the shift map. Because actual acceleration G exceeds allowable acceleration Ga at time t2, it is considered that the driver does not want transmission 23 to downshift, but rather wants actual vehicle speed V and actual acceleration G to increase at the current gear. In this case, downshift suppression control unit 120 suppresses downshifting by transmission control unit 110, i.e., prohibits downshifting. This suppresses unnecessary downshifting, making it possible to effectively prevent shift shock associated with downshifting.

[0039] At time t3, when the actual acceleration G matches the target acceleration Gt, the difference between the actual vehicle speed V and the target vehicle speed Vt gradually decreases. When the actual vehicle speed V matches the target vehicle speed Vt at time t4, the transmission 23 is maintained in the current gear until an upshift condition is met in which the target driving force Ft exceeds the upshift line LU, or until a downshift condition is met in which the actual acceleration G is less than the allowable acceleration Ga when the target driving force Ft exceeds the downshift line LD.

[0040] 5 is a flowchart illustrating a processing routine executed by the downshift suppression control unit 120. This routine is started, for example, when the ACC control unit 100 executes ACC and the vehicle VH starts running.

[0041] In step S100, the downshift suppression control unit 120 acquires the target acceleration Gt calculated by the ACC control unit 100. When the ACC control unit 100 performs constant speed cruise control, the target acceleration Gt is calculated based on the deviation between the actual vehicle speed V and the target vehicle speed Vt, and when the ACC control unit 100 performs adaptive cruise control, the target acceleration Gt is calculated based on the deviation between the actual inter-vehicle distance D and the target inter-vehicle distance Dt.

[0042] In step S110, the downshift suppression control unit 120 acquires the target driving force Ft calculated by the gear change control unit 110. The target driving force Ft is calculated based on the actual vehicle speed V and the target acceleration Gt of the ACC. Note that the processes of step S100 and step S110 may be performed simultaneously.

[0043] In step S120, the downshift suppression control unit 120 determines whether a downshift condition is established, in which the target driving force Ft acquired in step S110 exceeds the downshift line on the shift map. If the target driving force Ft does not exceed the downshift line on the shift map (No), that is, if the downshift condition is not established, the downshift suppression control unit 120 returns to the processing of step S100. On the other hand, if the target driving force Ft exceeds the downshift line on the shift map (Yes), that is, if the downshift condition is established, the downshift suppression control unit 120 proceeds to the processing of step S130.

[0044] In step S130, the downshift suppression control unit 120 acquires the allowable acceleration Ga corresponding to the actual vehicle speed V by referring to the allowable acceleration map M based on the actual vehicle speed V. Next, in step S140, the downshift suppression control unit 120 determines whether the actual acceleration G is equal to or greater than the allowable acceleration Ga. If the actual acceleration G is not equal to or greater than the allowable acceleration Ga (No), that is, if the actual acceleration G is smaller than the allowable acceleration Ga, the downshift suppression control unit 120 proceeds to processing in step S150, permits the gear shift control unit 110 to perform a downshift, and returns from this routine. On the other hand, if the actual acceleration G is equal to or greater than the allowable acceleration Ga (Yes), the downshift suppression control unit 120 proceeds to processing in step S160, and suppresses the gear shift control unit 110 from performing a downshift, that is, prohibits the downshift. If the downshift suppression control unit 120 prohibits the downshift in step S160, the downshift suppression control unit 120 returns from this routine.

[0045] According to the vehicle control device of this embodiment described above in detail, the ECU 10 includes an ACC control unit 100 that executes the ACC, a transmission control unit 110 that upshifts or downshifts the transmission 23 based on the target driving force Ft of the vehicle VH, and a downshift suppression control unit 120 that suppresses downshifts by the transmission control unit 110 while the ACC is being executed. Even when a downshift condition exists in which the target driving force Ft exceeds the downshift line LD while the ACC is being executed, the downshift suppression control unit 120 suppresses downshifts by the transmission control unit 110 if the relationship between the actual acceleration G of the vehicle VH and a predetermined acceleration threshold different from the ACC target acceleration Gt satisfies a specific condition, specifically, if the actual acceleration G is equal to or greater than the allowable acceleration Ga. This prohibits unnecessary downshifts that the driver does not want while the ACC is being executed, preventing the occurrence of gear shift shock associated with downshifts and reliably improving drivability.

[0046] The vehicle control device according to this embodiment has been described above, but the present disclosure is not limited to the above embodiment, and various modifications are possible without departing from the purpose of the present disclosure.

[0047] For example, in the above embodiment, the vehicle VH has been described as a vehicle capable of executing ACC (constant speed cruise control and adaptive cruise control), but it may also be a vehicle capable of only executing cruise control (constant speed cruise control). Furthermore, the permissible acceleration Ga has been described as a variable value that corresponds to the actual vehicle speed V, but it may be a fixed value, or a variable value that corresponds to a parameter other than the actual vehicle speed V. An example of a parameter other than the actual vehicle speed V is the target inter-vehicle distance Dt for ACC. When the permissible acceleration Ga is a variable value that corresponds to the target inter-vehicle distance Dt, the longer the set target inter-vehicle distance Dt, the smaller the permissible acceleration Ga should be. Furthermore, the permissible acceleration Ga may also be a variable value that corresponds to the external environment around the vehicle VH (e.g., outside temperature, rainfall, road surface conditions, time of day, etc.). The present disclosure may also be applied to autonomous vehicles that perform some or all of their driving operations automatically. [Explanation of symbols]

[0048] VH... vehicle, 10... ECU, 20... drive device, 23... transmission device, 30... internal sensor device, 40... external sensor device, 100... ACC control unit, 110... transmission control unit, 120... shift-down suppression control unit

Claims

1. A control device for a vehicle equipped with a transmission in a power transmission path that transmits power from a drive device to drive wheels, a travel control unit that sets a target acceleration of the vehicle based on either a predetermined target vehicle speed and an actual vehicle speed, or a predetermined target inter-vehicle distance and an actual inter-vehicle distance, and executes travel control to automatically control travel of the vehicle by operating the drive device based on the target acceleration; a gear shift control unit that sets a target driving force of the vehicle based on at least an actual vehicle speed and executes gear shift control to operate the transmission based on the target driving force; a downshift suppression control unit that acquires an actual acceleration during execution of the driving control by the driving control unit, and suppresses execution of a downshift of the transmission by the gear change control unit based on the actual acceleration and a predetermined acceleration threshold value different from the target acceleration, The acceleration threshold is set to decrease as the actual vehicle speed increases, and is set based on an allowable acceleration at which the driver of the vehicle feels that acceleration of the vehicle due to a downshift of the transmission is unnecessary. Vehicle control device.

2. The vehicle control device according to claim 1, the gear shift control unit downshifts the transmission when the target driving force exceeds a predetermined driving force threshold; The downshift suppression control unit suppresses the downshift by the gear change control unit when the actual acceleration is equal to or greater than the acceleration threshold, even if the target driving force exceeds the driving force threshold during execution of the driving control by the driving control unit. Vehicle control device.

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