Vehicle control system

Abstract

The present invention provides a vehicle control device that can suppress the over-revving of the vehicle's drive motor. [Solution] The vehicle 10 includes a front motor MGf, dog clutches 32 connected to the front motor MGf and a pair of front wheels 14, respectively, and an actuator 40 for engaging the dog clutches 32. The electronic control device 90 (a) determines whether the motor operating angle φact is greater than or equal to the operating angle determination value φact_jdg, (b) if it is determined that the motor operating angle φact is greater than or equal to the operating angle determination value φact_jdg, it increases the MGf torque Tmgf at an increase rate α that can reliably engage the meshing teeth 36d of the second gear 36 with the meshing teeth 34d of the first gear 34, and (c) if the MGf torque Tmgf becomes greater than or equal to the torque determination value Tmgf_jdg, it increases the MGf torque Tmgf at an increase rate β that is greater than the increase rate α.

Description

Technical Field

[0001] The present invention relates to a control device for a vehicle including a motor for vehicle drive, a dog clutch, and an actuator for engaging the dog clutch.

Background Art

[0002] There is known a vehicle equipped with a power transmission system including a motor for vehicle drive, a dog clutch for transmitting and blocking the power of the motor for vehicle drive, an actuator, an electric motor, a rotational speed sensor, a magnetic flux angle sensor, and a control device. For example, the vehicle described in Patent Document 1 is such a vehicle. In the vehicle described in Patent Document 1, frequency analysis is performed on the magnetic flux angle detected by a magnetic flux angle sensor provided at a position where the first gear teeth and the second gear teeth of the dog clutch are in an engaged state (= meshed state), and the completion of engagement of the dog clutch is determined based on the analysis result.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, it is conceivable to configure the system to determine whether the dog clutch is engaged or not based on the operating angle of the actuator, rather than on the magnetic flux angle sensor. However, in such a configuration, the state of the first and second gear teeth of the dog clutch is not directly detected, resulting in poor accuracy in determining whether the dog clutch is engaged or not. For example, if the teeth that the dog clutch is trying to engage are repelled, and even if it tries to engage again, it is repelled by the next tooth, a so-called uplock state occurs, the dog clutch may be mistakenly determined to be engaged even though it is not. If the dog clutch is mistakenly determined to be engaged, increasing the output torque of the vehicle drive motor may cause the vehicle drive motor to over-rev.

[0005] The present invention was made against the above circumstances, and its objective is to provide a vehicle control device that can suppress the over-revving of a vehicle drive motor. [Means for solving the problem]

[0006] The gist of the present invention is a control device for a vehicle comprising: a vehicle drive motor; a dog clutch comprising a first rotating member and a second rotating member having meshing teeth facing each other, wherein the vehicle drive motor is connected to the first rotating member and a wheel is connected to the second rotating member; and an actuator that engages the dog clutch by bringing one of the first rotating member and the second rotating member closer to the other, wherein (a) it is determined whether the operating angle of the actuator is a predetermined operating angle that can engage the dog clutch; (b) if it is determined that the operating angle of the actuator is the predetermined operating angle, the output torque of the vehicle drive motor is increased at a first increase rate that can reliably engage one of the first rotating member and the second rotating member with the other; and (c) if the output torque exceeds a predetermined value, the output torque is increased at a second increase rate that is greater than the first increase rate. [Effects of the Invention]

[0007] According to the vehicle control device of the present invention, (a) it is determined whether the operating angle of the actuator is a predetermined operating angle that can engage the dog clutch; (b) if it is determined that the operating angle of the actuator is the predetermined operating angle, the output torque of the vehicle drive motor is increased at a first increase rate that can reliably engage one of the first rotating member and the second rotating member with the other; and (c) if the output torque exceeds a predetermined value, the output torque is increased at a second increase rate that is greater than the first increase rate. In this way, when it is determined that the operating angle of the actuator is a predetermined operating angle that can engage the dog clutch, the output torque of the vehicle drive motor is increased at a first increase rate that can reliably engage the first rotating member and the second rotating member of the dog clutch. As a result, a so-called uplock state in the dog clutch does not occur, and the dog clutch is reliably engaged. When the output torque of the vehicle drive motor rises to a predetermined value or higher, the increase rate for increasing the output torque of the vehicle drive motor is increased. This suppresses the occurrence of an uplock state in the dog clutch, and also suppresses the occurrence of the vehicle drive motor over-revving, which can occur when the dog clutch is mistakenly identified as engaged. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram illustrates the schematic configuration of a vehicle to which the present invention is applied. [Figure 2] This diagram illustrates the schematic configuration of the dog clutch and actuator. [Figure 3] This is an example of a flowchart illustrating the key aspects of the control operation of an electronic control unit. [Figure 4] This figure shows an example of a time chart when the control operation shown in the flowchart in Figure 3 is performed. [Modes for carrying out the invention]

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the embodiments, the drawings have been simplified or modified as appropriate, and the dimensional ratios and shapes of each part are not necessarily depicted accurately. [Examples]

[0010] Figure 1 is a diagram illustrating the schematic configuration of a vehicle 10 to which the present invention is applied.

[0011] Vehicle 10 is equipped with a front motor MGf and a rear motor MGr as power sources for driving. The front motor MGf and rear motor MGr are well-known motor generators. The "front motor MGf" corresponds to the "vehicle drive motor" in this invention.

[0012] Vehicle 10 is equipped with a power transmission path between the front motor MGf and a pair of front wheels 14 (hereinafter simply referred to as "front wheels 14"), in order from the front motor MGf side, a rotating shaft 22, a disconnection device 30, a rotating shaft 38, a front differential gear 16, and a pair of front drive shafts 18, which are well-known configurations. "Front wheels 14" corresponds to "wheels" in this invention. Vehicle 10 is equipped with a power transmission path between the rear motor MGr and a pair of rear wheels 54 (hereinafter simply referred to as "rear wheels 54"), in order from the rear motor MGr side, a rear differential gear 56 and a pair of rear drive shafts 58, which are well-known configurations. Vehicle 10 can select between a two-wheel drive driving mode and a four-wheel drive driving mode. When the disconnection device 30 is engaged (=connected), vehicle 10 is equipped with the four-wheel drive driving mode. When the disconnection device 30 is released (i.e., the dog clutch 32 is not engaged), the vehicle 10 is set to a two-wheel drive mode. For example, the rear wheels 54 are the main drive wheels, which are driven wheels in both two-wheel drive and four-wheel drive modes. For example, the front wheels 14 are the secondary drive wheels, which are driven wheels in two-wheel drive mode and drive wheels in four-wheel drive mode.

[0013] The disconnection device 30 is a well-known disconnection device that includes a dog clutch 32 for disconnecting and connecting power transmission between the rotating shaft 22 and the rotating shaft 38, and an actuator 40 for controlling the disconnected and connected state of the dog clutch 32.

[0014] Vehicle 10 is equipped with an inverter 60 for front motor drive control, an inverter 62 for rear motor drive control, and an electronic control unit 90. Inverters 60 and 62 are well-known power supply circuits that convert DC to AC and AC to DC, respectively. The front motor MGf and rear motor MGr are connected to a battery (not shown) via inverters 60 and 62, respectively. The output torque of the front motor MGf and rear motor MGr is controlled by the control of inverters 60 and 62 by the electronic control unit 90, respectively.

[0015] Figure 2 is a diagram illustrating the schematic configuration of the dog clutch 32 and actuator 40.

[0016] The dog clutch 32 comprises a first gear 34 connected to the rotating shaft 22 so as to be unable to rotate relative to it and unable to move in the axial direction CL, and a second gear 36 connected to the rotating shaft 38 so as to be unable to rotate relative to it and able to move in the axial direction CL. The first gear 34 is provided with meshing teeth 34d, and the second gear 36 is provided with meshing teeth 36d. The meshing teeth 34d and 36d face each other and are able to mesh. The second gear 36 is provided with an engaging projection 36a. The first gear 34 and the second gear 36 correspond to the "first rotating member" and the "second rotating member" in the present invention, respectively.

[0017] The actuator 40 comprises an actuator motor 42, an intermediate member 44, a spring 46, and a shift fork 48. The spring 46 is provided between the intermediate member 44 and the shift fork 48. The spring 46 is, for example, a compression coil spring. The shift fork 48 is provided with a groove 48m. The groove 48m engages with an engaging projection 36a. The actuator motor 42 can move the intermediate member 44 in the direction of the axis CL (the direction of the white arrow A or white arrow B) by its rotation. The axis CL is the rotational centerline common to the rotation axis 22, the rotation axis 38, the first gear 34, and the second gear 36. When the intermediate member 44 is moved in the direction of the white arrow A, the shift fork 48 is also moved in the direction of the white arrow A via the spring 46. When the shift fork 48 is moved in the direction of the white arrow A, the second gear 36 is moved in the direction of the white arrow A via the engaging projection 36a. As a result, when the meshing teeth 34d and 36d are engaged, the dog clutch 32 is engaged. In this way, the actuator 40 engages the dog clutch 32 by moving the second gear 36 closer to the first gear 34. The second gear 36 corresponds to "one of the first and second rotating members" in this invention, and the first gear 34 corresponds to "the other of the first and second rotating members" in this invention. When the intermediate member 44 is moved in the direction of the white arrow B by the actuator motor 42, the second gear 36 is moved away from the first gear 34, thereby releasing the dog clutch 32.

[0018] Returning to Figure 1, the electronic control unit 90 is a controller that includes control devices for controlling the front motor MGf, the disconnection device 30, the rear motor MGr, etc. The electronic control unit 90 is composed of a so-called microcomputer equipped with, for example, a CPU, RAM, ROM, input / output interface, etc. In this embodiment, the electronic control unit 90 is composed of a front motor ECU 94 that controls the front motor MGf, a dog clutch ECU 96 that controls the disconnection state of the disconnection device 30, a rear motor ECU 98 that controls the rear motor MGr, and an integrated ECU 92 that controls them in an integrated manner. Note that ECU stands for Electronic Control Unit, and is an acronym formed by taking the first letter of each word. In the electronic control unit 90, the front motor ECU 94, the dog clutch ECU 96, the rear motor ECU 98, and the integrated ECU 92 are each connected to a communication network using, for example, a CAN communication circuit. Note that the electronic control unit 90 corresponds to the "control device" in the present invention.

[0019] The integrated ECU 92 receives various signals (for example, vehicle speed V [km / h], accelerator opening θacc [%], MGf rotation speed Nmgf [rpm] which is the rotation speed of the front motor MGf, MGr rotation speed Nmgr [rpm] which is the rotation speed of the rear motor MGr, motor operation angle φact [deg] representing the rotation position of the actuator motor 42, rotation speed Na [rpm] which is the rotation speed of the rotary shaft 22, rotation speed Nb [rpm] which is the rotation speed of the rotary shaft 38, etc.) based on the detection values from various sensors (for example, vehicle speed sensor 70, accelerator opening sensor 72, MGf rotation speed sensor 74, MGr rotation speed sensor 76, rotation angle sensor 78, rotation speed sensor 80, rotation speed sensor 82, etc.). The integrated ECU 92 calculates the required drive torque Trdem [N·m], which is the drive torque required by the driver for the vehicle 10, based on the vehicle speed V and the accelerator opening θacc. The front motor ECU 94 outputs a control signal Smgf for rotationally controlling the front motor MGf to the inverter 60. The dog clutch ECU 96 outputs a control signal Sdclt for controlling the operation angle of the actuator motor 42 to the actuator motor 42. The rear motor ECU 98 outputs a control signal Smgr for rotationally controlling the rear motor MGr to the inverter 62. The integrated ECU 92 controls the front motor MGf, the dog clutch 32, and the rear motor MGr via the front motor ECU 94, the dog clutch ECU 96, and the rear motor ECU 98 based on the selected driving mode and the required drive torque Trdem.

[0020] Hereinafter, the case where the vehicle 10 is switched from the two-wheel drive running mode to the four-wheel drive running mode by the electronic control device 90 will be described.

[0021] During running in the two-wheel drive running mode, the dog clutch 32 is in the released state. The rotation speed Nb, which is the rotation speed of the rotary shaft 38, has a rotation speed corresponding to the vehicle speed V due to the driven force from the front wheels 14. Since the front motor MGf has stopped rotating, the rotation speed Na, which is the rotation speed of the rotary shaft 22, is a zero value.

[0022] When a request is made to switch to four-wheel drive driving mode, the electronic control unit 90 starts synchronous control to make the rotational speed Na the same as the rotational speed Nb. In synchronous control, the MGf rotational speed Nmgf is controlled so that the rotational speed Na is the same as the rotational speed Nb. The rotational speed Nb is the synchronous rotational speed Nsyn [rpm], which is the target value of the rotational speed Na in synchronous control. When the difference rotation ΔN (=|Na-Nb|), which is the absolute value of the difference between the rotational speed Na and the rotational speed Nb, becomes less than the difference rotation determination value ΔN_jdg, the electronic control unit 90 starts engagement control to engage the dog clutch 32. The "difference rotation determination value ΔN_jdg" is a predetermined determination value for the difference rotation ΔN that is experimentally or design-defined in advance, in which engagement control of the dog clutch 32 is considered feasible. In engagement control, the electronic control unit 90 rotates the actuator motor 42 so that the intermediate member 44 moves in the direction of the white arrow A.

[0023] When the motor operating angle φact becomes greater than or equal to the operating angle determination value φact_jdg due to engagement control, the electronic control device 90 stops the rotation of the actuator motor 42 and then starts torque recovery rate suppression control. "Motor operating angle φact" corresponds to "actuator operating angle" in this invention. "Operating angle determination value φact_jdg" is a predetermined operating angle of the motor operating angle φact that can be entered into an engaged state experimentally or by design. "The motor operating angle φact being greater than or equal to the operating angle determination value φact_jdg" corresponds to "the actuator operating angle being a predetermined operating angle that can enter into an engaged state of the dog clutch 32" in this invention. When the motor operating angle φact becomes greater than or equal to the operating angle determination value φact_jdg, the second gear 36 is pressed towards the first gear 34 side via the shift fork 48 by the biasing force of the spring 46 so that the meshing teeth 36d engage with the meshing teeth 34d. In torque recovery rate suppression control, the increase in MGf torque Tmgf [N·m] per unit time is defined as the increase rate α [N·m / s]. MGf torque Tmgf is the output torque of the front motor MGf and corresponds to the "output torque of the vehicle drive motor" in this invention. The "increase rate α" is a predetermined increase rate experimentally or by design that ensures the dog clutch 32 is reliably engaged, and corresponds to the "first increase rate" in this invention. The increase rate α will be described later.

[0024] After the torque recovery rate suppression control is performed, the electronic control unit 90 determines whether the MGf torque Tmgf has become equal to or greater than the torque determination value Tmgf_jdg. The "torque determination value Tmgf_jdg" corresponds to the "predetermined value" in this invention. The "torque determination value Tmgf_jdg" is a predetermined torque value that can be determined to be engaged when the meshing teeth 36d and 34d mesh and the dog clutch 32 is engaged. If it is determined that the MGf torque Tmgf has become equal to or greater than the torque determination value Tmgf_jdg, the electronic control unit 90 starts normal torque recovery rate control. In normal torque recovery rate control, the increase in MGf torque Tmgf per unit time is set to an increase rate β [N·m / s] (>α). The increase rate β is greater than the increase rate α. The "increase rate β" is a predetermined increase rate, experimentally or by design, that ensures the switching period from two-wheel drive mode to four-wheel drive mode is within an acceptable range, and corresponds to the "second increase rate" in this invention. After the execution of torque recovery rate normal control, the electronic control unit 90 controls the front motor MGf and the rear motor MGr so that the sum of the front wheel drive torque Tlf [N·m] and the rear wheel drive torque Trr [N·m], Tsum [N·m], is equal to or greater than the required drive torque Trdem. The MGr torque Tmgr is the output torque of the rear motor MGr. The front wheel drive torque Tlf is the torque transmitted to the front wheels 14 by the MGf torque Tmgf, and the rear wheel drive torque Trr is the torque transmitted to the rear wheels 54 by the MGr torque Tmgr.

[0025] Figure 3 is an example of a flowchart illustrating the main parts of the control operation of the electronic control unit 90. The flowchart in Figure 3 is executed when a request to switch to four-wheel drive mode is received while driving in two-wheel drive mode.

[0026] First, in step S10 (hereinafter, "step" will be omitted), synchronous control is started. After the execution of S10, in S20, it is determined whether the differential rotation ΔN is less than the differential rotation determination value ΔN_jdg. If the determination of S20 is NO, S20 is executed again. If the determination of S20 is YES, in S30, engagement control of the dog clutch 32 is started, and in S40, it is determined whether the motor operating angle φact is greater than or equal to the operating angle determination value φact_jdg. If the determination of S40 is NO, S40 is executed again. If the determination of S40 is YES, in S50, torque return rate suppression control is started. In torque return rate suppression control, in order for the meshing teeth 34d of the first gear 34 and the meshing teeth 36d of the second gear 36 to mesh reliably, the following equation (1) must hold. Here, inertia I [kg·m 2 ] is the moment of inertia of the power transmission path from the front motor MGf to the meshing tooth 34d. The natural frequency f [Hz] is the frequency (reciprocal of the period) at which the tooth tips repel each other and attempt to re-engage when the meshing teeth 36d and 34d are in an uplocked state, and are repelled by the next tooth tip. The natural frequency f is affected by, for example, the spring constant of spring 46. The number of teeth n is the number of teeth of the meshing tooth 36d (= number of teeth of the meshing tooth 34d).

number

[0027] The left side of equation (1) is the ratio of the MGf torque Tmgf to the inertia I (= Tmgf / I), which is the time integral of the angular acceleration of the rotation axis 22, and represents the angular velocity of the rotation axis 22. The right side of equation (1) represents the angular velocity of the rotation axis 38 when the teeth of the meshing teeth 36d and 34d are in an uplocked state, and when they are repelled from each other and attempt to re-engage, they are repelled again by the next tooth. In equation (1), the fact that the left side is smaller than the right side means that even if the teeth of the meshing teeth 36d and 34d are repelled from each other, the meshing tooth 36d can mesh with the meshing tooth 34d before the next tooth of the meshing tooth 34d arrives. The aforementioned increase rate α is set so that equation (1) holds true.

[0028] After execution of S50, in S60, it is determined whether the MGf torque Tmgf is equal to or greater than the torque determination value Tmgf_jdg after the torque recovery rate suppression control is performed. The aforementioned "torque determination value Tmgf_jdg" is, for example, the MGf torque Tmgf when the left and right sides of equation (1) are equal. If the determination in S60 is NO, S60 is executed again. If the determination in S60 is YES, torque recovery rate normal control is started in S70, and in S80, it is determined whether the total torque Tsum is equal to or greater than the requested drive torque Trdem. If the determination in S80 is NO, S80 is executed again. If the determination in S80 is YES, torque recovery rate normal control is completed, the switch to four-wheel drive driving mode is completed, and the flowchart in Figure 3 ends. After the switch to four-wheel drive driving mode is completed, the total torque Tsum is controlled to become the requested drive torque Trdem.

[0029] Figure 4 shows an example of a time chart when the control operation shown in the flowchart of Figure 3 is performed. The horizontal axis in Figure 4 is time t [s]. In Figure 4, this embodiment is shown with a solid line, and the comparative example is shown with a dashed line. The comparative example is an example in which, after time point t3 described later, torque recovery rate normal control is started instead of torque recovery rate suppression control, and an uplock state occurs in the dog clutch 32.

[0030] First, let's explain this embodiment (shown by the solid line in Figure 4).

[0031] In Figure 4, time t1 is the point in time when a request to switch to four-wheel drive mode is made while driving in two-wheel drive mode. Synchronous control starts at time t1, and engagement control starts at time t2 (>t1) when the differential rotation ΔN becomes less than the differential rotation judgment value ΔN_jdg. Torque recovery rate suppression control starts at time t3 (>t2) when the motor operating angle φact becomes greater than or equal to the operating angle judgment value φact_jdg. At time t4 (>t3), after the execution of torque recovery rate suppression control, the MGf torque Tmgf reaches the torque judgment value Tmgf_jdg. From time t4 onward, normal torque recovery rate control starts, and at time t5 (>t4), the total torque Tsum becomes the requested drive torque Trdem.

[0032] Next, we will explain the comparative example (shown by the dashed line in Figure 4).

[0033] Prior to time t3, the process is the same as in the embodiment described above. At time t3, normal torque recovery rate control is initiated. In normal torque recovery rate control, the dog clutch 32 is not guaranteed to be engaged, so an uplock state may occur in the dog clutch 32, causing the dog clutch 32 to become disengaged. When an uplock state occurs in the dog clutch 32, the front motor MGf revs up as the MGf torque Tmgf increases, causing the MGf rotational speed Nmgf to rise sharply.

[0034] According to this embodiment, (a) it is determined whether the motor operating angle φact is greater than or equal to the operating angle determination value φact_jdg, (b) if it is determined that the motor operating angle φact is greater than or equal to the operating angle determination value φact_jdg, the MGf torque Tmgf is increased at an increase rate α that can reliably engage the meshing teeth 36d of the second gear 36 with the meshing teeth 34d of the first gear 34, and (c) if the MGf torque Tmgf becomes greater than or equal to the torque determination value Tmgf_jdg, the MGf torque Tmgf is increased at an increase rate β that is greater than the increase rate α. In this way, when it is determined that the motor operating angle φact is greater than or equal to the operating angle determination value φact_jdg, the MGf torque Tmgf is increased at an increase rate α that can reliably engage the meshing teeth 34d of the first gear 34 and the meshing teeth 36d of the second gear 36 of the dog clutch 32. As a result, an uplock state does not occur in the dog clutch 32, and the dog clutch 32 is reliably engaged. Then, when the MGf torque Tmgf rises to or above the torque judgment value Tmgf_jdg, the rate at which the MGf torque Tmgf is increased is significantly increased. This suppresses the occurrence of an uplock state in the dog clutch 32 and suppresses the occurrence of the front motor MGf over-revving, which occurs when the dog clutch 32 is mistakenly judged to be engaged. In addition, the occurrence of abnormal noise and ratcheting in the dog clutch 32 can also be suppressed. "Ratcheting" here refers to the phenomenon in which deformation of the meshing teeth 34d and 36d of the dog clutch 32 accumulates in one direction due to repeated mechanical load in the uplock state.

[0035] The above-described examples are embodiments of the present invention, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art, without departing from its spirit.

[0036] In the above-described embodiment, the actuator 40 engaged the dog clutch 32 by bringing the second gear 36 closer to the first gear 34. However, the present invention is not limited to this, and any configuration in which the dog clutch 32 is engaged by bringing one of the first gear 34 and the second gear 36 closer to the other is acceptable.

[0037] In the above-described embodiment, the dog clutch 32 was provided in the power transmission path between the front motor MGf and the front wheel 14. However, the present invention is also applicable to an embodiment in which the dog clutch 32 is provided in the power transmission path between the rear motor MGr and the rear wheel 54. In this embodiment, the rear wheel 54 corresponds to the "wheel" in the present invention.

[0038] In the above-described embodiment, no transmission was provided between the front motor MGf and the front differential gear 16, nor between the rear motor MGr and the rear differential gear 56. However, the present invention is also applicable to embodiments in which a transmission is provided. [Explanation of Symbols]

[0039] 10: Vehicle, 14: Pair of front wheels, 32: Dog clutch, 34: First gear (first rotating member), 34d: Meshing teeth, 36: Second gear (second rotating member), 36d: Meshing teeth, 40: Actuator, 90: Electronic control unit (control unit), MGf: Front motor (vehicle drive motor), Tmgf: MGf torque (output torque of vehicle drive motor), Tmgf_jdg: Torque determination value (predetermined value), α: Increase rate (first increase rate), β: Increase rate (second increase rate), φact: Motor operating angle (actuator operating angle)

Claims

[Claim 1] A control device for a vehicle comprising: a vehicle drive motor; a dog clutch comprising a first rotating member and a second rotating member having meshing teeth facing each other, wherein the vehicle drive motor is connected to the first rotating member and a wheel is connected to the second rotating member; and an actuator that engages the dog clutch by bringing one of the first rotating member and the second rotating member closer to the other, Determine whether the operating angle of the actuator is a predetermined operating angle that can engage the dog clutch. When it is determined that the operating angle of the actuator is the predetermined operating angle, the output torque of the vehicle drive motor is increased at a first increase rate that ensures one of the first rotating member and the second rotating member is reliably engaged with the other. When the output torque exceeds a predetermined value, the output torque is increased at a second increase rate that is greater than the first increase rate. A vehicle control device characterized by the following features.

Images