Vehicle control system

Abstract

To provide a vehicle control device capable of changing a shift range to an N range while suppressing the occurrence of shock even an automatic-return-type shift lever is operated to an N position for a short time.SOLUTION: A vehicle 10 includes an automatic-return-type shift lever 42 that is to be operated to change a shift range. When a shift range is a D range, the vehicle is running under a regenerative control, and when the shift lever 42 is held at an N position for a duration longer than or equal to a predetermined held time period Phld, an electric control device 90 of the vehicle 10 executes, for a predetermined control time period Pctrl, a braking force cooperative control that progressively reduces regenerative torque Tmg and progressively increases wheel brake torque Twb, and then changes the shift range to an N range.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] Relates to a control device for a vehicle having a self - returning operator that is operated to switch a shift range.

Background Art

[0002] When the shift lever is switched from the D position (= forward driving range) to the N position (= neutral range) during regenerative control, a shock occurs because the twist in the rotational direction of the axle or the like due to the regenerative torque is suddenly released by the switching of the shift range. To suppress the occurrence of this shock, a vehicle control device that executes braking force cooperative control to gradually decrease the regenerative torque and gradually increase the wheel brake torque in advance when the shift lever is switched from the D position to the N position is known. For example, the one described in Patent Document 1 is such. In Patent Document 1, when the shift lever is operated from the D position to the N position, during the period when it is being operated to the N position, braking force cooperative control to gradually decrease the regenerative torque and gradually increase the wheel brake torque in advance is executed, thereby suppressing the occurrence of a shock.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Unlike the configuration described in Patent Document 1, a shift operation device of the so-called shift-by-wire type, in which the shift lever is of the automatic return type, is known. In such a shift operation device, when the shift lever is operated by the driver from the initial position H to the N position and held there, it is conceivable that, similar to Patent Document 1, braking force coordinated control is performed during the period in which the regenerative torque is gradually reduced and the wheel brake torque is gradually increased in advance to suppress the occurrence of shock.

[0005] Incidentally, in automatic return shift operation devices, there is a type of operation called "short-term N operation" in which the driver operates the shift lever from the H position to the N position to switch the shift range to the N range, and then immediately returns it to the H position. "Short-term N operation" is an operation in which the shift lever is held in the N position for a predetermined holding period longer than a set period, and then immediately returned to the H position. If the predetermined holding period is set to be long, the driver must hold the shift lever for a long time in order to switch the shift range to the N range, which becomes a cumbersome operation for the driver. On the other hand, if the predetermined holding period is set to be short, the period in which the shift lever is operated and held in the N position is short, and there is insufficient time to reduce the regenerative torque, which may cause a shock.

[0006] The present invention was made against the above circumstances, and its objective is to provide a vehicle control device that can switch the shift range to the N range while suppressing the occurrence of shocks, even when an automatically returning shift lever is operated to the N position for a short period of time. [Means for solving the problem]

[0007] The gist of the present invention is a control device for a vehicle equipped with an automatic return type control element operated to switch the shift range, wherein, while the vehicle is driving in the driving range and regenerative control is in progress, if the control element is held in the N position for selecting the N range for a predetermined first period of time or longer, the device performs braking force coordinated control for a predetermined second period of time, which involves gradually decreasing the regenerative torque and gradually increasing the wheel brake torque, and then switches the shift range to the N range. [Effects of the Invention]

[0008] According to the vehicle control device of the present invention, when the shift range is set to the driving range and regenerative control is in progress, if the operator is held in the N position for a predetermined first period of time or longer, a braking force coordinated control is performed for a predetermined second period, gradually reducing the regenerative torque and gradually increasing the wheel brake torque, after which the shift range is switched to the N range. In this way, the regenerative torque is gradually reduced by the braking force coordinated control performed for the predetermined second period. After the predetermined second period has elapsed, the twisting of the power transmission path due to the regenerative torque is sufficiently reduced, so even when the shift range is switched to the N range, the occurrence of shock is suppressed. Therefore, even if the shift lever is operated to the N position for a short period of time, the shift range is switched to the N range while the occurrence of shock is suppressed. [Brief explanation of the drawing]

[0009] [Figure 1] This diagram shows a schematic configuration of a vehicle equipped with an electronic control device according to an embodiment of the present invention, as well as a functional block diagram representing the main parts of the control functions for various controls in the vehicle. [Figure 2] Figure 1 shows an example of a flowchart illustrating the control operation of the electronic control unit. [Figure 3] This is an example of a time chart when the flowchart in Figure 2 is executed. [Modes for carrying out the invention]

[0010] 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]

[0011] Figure 1 is a schematic diagram of a vehicle 10 equipped with an electronic control device 90 according to an embodiment of the present invention, as well as a functional block diagram showing the main parts of the control functions for various controls in the vehicle 10.

[0012] Vehicle 10 is a vehicle equipped with an engine 12 and an electric motor MG, which are power sources for driving, and a power transmission device 16 provided in the power transmission path PT between the engine 12 and a pair of drive wheels 14. Vehicle 10 also includes a shift operation device 40, an indicator 50, a hydraulic control circuit 60, an inverter 62, a battery 64, and an electronic control device 90.

[0013] Engine 12 is a well-known internal combustion engine. The engine torque Te [Nm], which is the output torque of engine 12, is controlled by the electronic control unit 90. The electric motor MG is a so-called motor generator that has, for example, the function of an electric motor (i.e., motor function) and the function of a generator (i.e., generator function). The electric motor MG is, for example, a three-phase synchronous motor.

[0014] The power transmission device 16, in order from the engine 12 side, comprises an engine connecting shaft 30, a clutch K0, an electric motor connecting shaft 32, a torque converter 20, an input shaft 34 which is the input rotating member of the automatic transmission 22, the automatic transmission 22, etc., within a case 18, as well as an output shaft 36 which is the output rotating member of the automatic transmission 22, a differential 24, a pair of axles 38, etc., all of which are well-known configurations. The case 18 is a non-rotating member attached to the vehicle body. The clutch K0 is a friction engagement device that disconnects and connects power transmission between the engine connecting shaft 30 connected to the engine 12 and the electric motor connecting shaft 32 connected to the rotor of the electric motor MG, and is, for example, a wet multi-plate type hydraulic friction engagement device. In this specification, unless otherwise specified, torque, driving force, power, and force (power) are synonymous.

[0015] The automatic transmission 22 is a well-known automatic transmission, such as a planetary gear type or a normally meshing parallel shaft type transmission. The automatic transmission 22 is controlled by a hydraulic control circuit 60 controlled by an electronic control device 90 so that a desired gear ratio γat is formed from among different gear ratios γat. The gear ratio γat is the rotational speed ratio (=Nin / Nout) of the input shaft rotational speed Nin [rpm] and the output shaft rotational speed Nout [rpm]. The input shaft rotational speed Nin is the rotational speed of the input shaft 34, and the output shaft rotational speed Nout is the rotational speed of the output shaft 36.

[0016] The hydraulic control circuit 60 uses the hydraulic fluid discharged by the oil pump 68 as the source pressure and supplies regulated hydraulic pressure to actuators that perform engagement / disengagement control of the lock-up clutch LU of the torque converter 20 and actuators that perform shift control of the automatic transmission 22.

[0017] The shift control device 40 is an operating device for selecting one of several shift ranges. That is, the shift control device 40 is an operating device that accepts a request to switch the shift range when operated manually. The shift control device 40 is, for example, located near the driver's seat and has an operating element that can be selectively operated by the driver to multiple operating positions corresponding to multiple shift ranges. The shift range represents the power transmission state from the engine 12 and electric motor MG, which are the power sources for driving, to the pair of drive wheels 14, and includes, for example, the R range, N range, D range, P range, etc., which will be described later.

[0018] The shift operation device 40 employs a so-called shift-by-wire system. The shift operation device 40 comprises, for example, a shift lever 42 and a P switch 46. Both the shift lever 42 and the P switch 46 are momentary type controls that return to their original position (initial position) when no external force is applied. In other words, the shift lever 42 and the P switch 46 are controls that return to their initial position when not operated by the driver (in other words, they are self-returning controls that automatically return to their initial position when the operating force is released). The shift lever 42 corresponds to the "controller" in this invention.

[0019] The operating positions of the shift lever 42 are, for example, the operating positions of "H position", "R position", "N position", "D position", and "B position". The "H position" is the initial position (home position) of the shift lever 42. Even if the shift lever 42 is operated to an operating position other than the "H position", if the driver releases the shift lever 42 (i.e., when the external force acting on the shift lever 42 disappears), the shift lever 42 is returned to the "H position" by a mechanical mechanism such as a spring. The "R position" is an operating position for selecting the R range that enables the vehicle 10 to reverse. The "N position" is an operating position for selecting the N range in a neutral state where the power transmission from the power source for driving to the pair of drive wheels 14 is blocked. For example, in the N range, the automatic transmission 22 is set in the neutral state. The "D position" is an operating position for selecting the D range that enables the vehicle 10 to move forward. The "B position" is a decelerating forward driving state selection operating position that makes it easy for the engine brake using the engine 12 to act (i.e., a state where a stronger engine brake effect can be obtained) when the power transmission path PT for forward driving is formed by an operation to the "D position".

[0020] The P switch 46 is, for example, a momentary push button switch. When pushed by the driver, the power transmission from the power source for driving to the pair of drive wheels 14 is blocked to enter a neutral state, and the P range (= parking range) in which the pair of drive wheels 14 are mechanically fixed so that they cannot rotate is selected. When the P switch 46 is not being pushed, the P switch 46 is in its initial position (home position). Even if the P switch 46 has been pushed, if the driver releases the P switch 46, the P switch 46 is returned to the initial position by a mechanical mechanism such as a spring. The "D range" and "R range" are driving ranges, and the "P range" and "N range" are non - driving ranges. Note that the "N range" and "D range" respectively correspond to the "N range" and "driving range" in the present invention.

[0021] In response to the P range, R range, N range, and D range of the shift range, the automatic transmission 22 is controlled to a P range in which its power transmission state is set to a neutral state and the output shaft 36 connected to the pair of drive wheels 14 is mechanically fixed so as not to rotate, an R range in which its power transmission state enables reverse travel, an N range in which its power transmission state is set to a neutral state, and a D range in which its power transmission state enables forward travel, respectively.

[0022] The indicator 50 is provided at a position that is easily visible to the driver and displays the currently selected shift range. The indicator 50 may display, for example, the actual power transmission state of the automatic transmission 22. In the shift operation device 40 of the present embodiment, since the shift lever 42 and the P switch 46 return to their initial positions when the external force applied to them disappears, the driver cannot recognize the currently selected shift range just by visually checking the shift lever 42 and the P switch 46. Therefore, it is useful to provide such an indicator 50.

[0023] The inverter 62 is a power supply circuit that converts direct current to alternating current or alternating current to direct current. The MG torque Tmg [Nm], which is the output torque of the electric motor MG, is controlled by the electronic control unit 90 via the inverter 62. When the MG torque Tmg is a positive value, the MG torque Tmg acts as a power source for driving the vehicle 10. When the MG torque Tmg is a negative value, the MG torque Tmg is a regenerative torque and acts as a braking force for decelerating the vehicle 10. Hereinafter, the MG torque Tmg (<0) that is a negative value will be referred to as the "regenerative torque Tmg". The determination of the magnitude of the regenerative torque Tmg shall mean the determination of the magnitude of the absolute value of the regenerative torque Tmg. For example, when the regenerative torque Tmg (<0) approaches zero, it is described as "the regenerative torque Tmg becomes smaller", and when the regenerative torque Tmg moves away from zero, it is described as "the regenerative torque Tmg becomes larger".

[0024] The battery 64 is a secondary battery and is the battery for driving the electric motor MG.

[0025] Vehicle 10 is equipped with a wheel brake device 26 as a braking device that applies a braking torque of wheel brake torque Twb [Nm] (<0) to the wheels (a pair of drive wheels 14 and a pair of driven wheels not shown). The wheel brake device 26 is a well-known electronic control brake. The wheel brake device 26 comprises a brake body 26a and a brake hydraulic pressure supply circuit 26b. The brake body 26a is a so-called disc brake, which obtains braking force by clamping brake pads between discs that rotate integrally with a pair of axles 38 connected to a pair of drive wheels 14 and a pair of axles connected to a pair of driven wheels not shown, and obtaining braking force through the frictional force. The brake hydraulic pressure supply circuit 26b supplies brake hydraulic pressure (also called brake braking hydraulic pressure) to a wheel cylinder provided in the brake body 26a according to the amount of brake operation Bra [%] by the driver, for example, by operating the brake pedal. The brake hydraulic pressure supply circuit 26b is a hydraulic actuator. In electronically controlled brakes, the optimal ratio of braking force for each wheel is calculated, and the braking force of each wheel is controlled to achieve that ratio.

[0026] Under normal circumstances, brake hydraulic pressure is supplied to the wheel cylinder so that the wheel brake torque Twb from the wheel brake device 26 becomes a braking force of a magnitude corresponding to the brake operation amount Bra. On the other hand, during regenerative control while decelerating in the D range, "braking force coordinated control" is possible, in which, for example, the vehicle braking torque TB [Nm], which is the sum of the regenerative torque Tmg and the wheel brake torque Twb, is controlled to become a braking force of a magnitude corresponding to the brake operation amount Bra. In other words, the wheel brake torque Twb can be controlled to be the braking force of a magnitude corresponding to the brake operation amount Bra (= vehicle braking torque TB) minus the regenerative torque Tmg. The regenerative torque Tmg is set to a value that does not exceed the torque capacity that the automatic transmission 22 can transmit. Furthermore, the vehicle braking torque TB does not need to be controlled to be exactly the same magnitude as the braking force corresponding to the brake operation amount Bra performed by the driver, but it is sufficient if it is controlled to be approximately the same magnitude within a range where the driver does not feel any discomfort due to a sudden change in braking force.

[0027] In the vehicle 10, for example, a driving mode in which only the electric motor MG is used as the power source for driving (BEV driving mode, hereinafter referred to as "BEV driving mode") and a driving mode in which at least the engine 12 is used as the power source for driving (hereinafter referred to as "engine driving mode") can be selected. In BEV driving mode, the clutch K0 is in the disengaged state, and in engine driving mode, the clutch K0 is in the engaged state.

[0028] The electronic control unit 90 is composed of a so-called microcomputer, for example, equipped with a CPU, RAM, ROM, input / output interface, etc. The CPU performs various controls on the vehicle 10 by performing signal processing according to a program pre-stored in ROM while utilizing the temporary storage function of RAM. For example, the electronic control unit 90 is configured to perform output control of the engine 12, output control of the electric motor MG, engagement / disengagement control of the clutch K0, and shift control of the automatic transmission 22. The electronic control unit 90 corresponds to the "control device" in this invention.

[0029] The electronic control unit 90 receives various signals based on values ​​detected by various sensors installed in the vehicle 10 (for example, lever position sensor 44, P switch 46, engine rotation speed sensor 70, input shaft rotation speed sensor 72, output shaft rotation speed sensor 74, MG rotation speed sensor 76, accelerator opening sensor 78, throttle valve opening sensor 80, brake operation amount sensor 82, battery sensor 84, etc.) (for example, lever position signal Slev, P switch signal Spsw, engine rotation speed which is the rotation speed of the engine 12). The following are inputs: Ne [rpm], input shaft rotation speed Nin which is the same as the turbine rotation speed Nt which is the rotation speed of the turbine blade, output shaft rotation speed Nout which corresponds to the vehicle speed V [km / h], MG rotation speed Nmg which is the rotation speed of the electric motor MG, accelerator opening θacc [%] which represents the amount of accelerator operation by the driver, throttle valve opening θth [%], brake operation amount Bra which represents the amount of deceleration operation by the driver, battery charge / discharge current Ibat [A], battery voltage Vbat [V], battery temperature THbat [℃], etc.

[0030] The electronic control unit 90 outputs various command signals (for example, engine control signal Se for controlling engine 12, wheel brake control signal Swb for controlling wheel brake torque Twb, shift range display signal Sindi for displaying the current shift range, shift control signal Sat for shifting automatic transmission 22, K0 control signal Sk0 for engaging and disengaging clutch K0, LU control signal Slu for engaging and disengaging lock-up clutch LU, MG control signal Smg for outputting electric motor MG via inverter 62, etc.) to each device installed in the vehicle 10 (for example, engine 12, brake hydraulic supply circuit 26b, indicator 50, hydraulic control circuit 60, inverter 62, etc.).

[0031] Next, we will explain the case where the shift lever 42 is briefly operated to the neutral position while the shift range is in the D range, BEV driving is in progress, and regenerative braking is active.

[0032] The electronic control unit 90 functionally includes a drive unit control unit 92 including a power source control unit 92a and a power transmission control unit 92b, a lever operation determination unit 94, a braking force control unit 96 including a wheel brake control unit 96a and a regenerative torque control unit 96b, and a range switching request unit 98.

[0033] The power source control unit 92a controls the output of the engine 12 and the electric motor MG, which are the power sources for driving. For example, by applying the accelerator opening θacc and vehicle speed V to a predetermined relationship (e.g., a drive torque map) which is experimentally or design-defined in advance, the power source control unit 92a calculates the required drive torque Trdem [Nm]. The power source control unit 92a controls the engine torque Te and MG torque Tmg so that the required drive torque Trdem is achieved, taking into account transmission losses, auxiliary loads, the gear ratio γat of the automatic transmission 22, etc. During BEV driving and regenerative control, the engine 12 is stopped and the engine torque Te is controlled to zero, and the regenerative torque Tmg is controlled to be a braking force of a magnitude corresponding to the brake operation amount Bra. If the regenerative torque Tmg exceeds the torque capacity that the automatic transmission 22 can transmit, the wheel brake torque Twb is controlled to be the excess amount.

[0034] The power transmission control unit 92b controls the torque transmitted from the power source for driving to the pair of drive wheels 14. The power transmission control unit 92b performs, for example, engagement and disengagement control of the clutch K0, engagement and disengagement control of the lock-up clutch LU, and gear shifting control of the automatic transmission 22. During BEV driving, the clutch K0 is controlled to be in the disengaged state, and the automatic transmission 22 is controlled to have a predetermined gear ratio γat in D range.

[0035] The lever operation determination unit 94 determines whether or not the shift lever 42 has been operated to position N. If the lever operation determination unit 94 determines that the shift lever 42 has been operated to position N, the lever operation determination unit 94 outputs N operation information indicating the timing at which the shift lever 42 was operated to position N. The N operation information is also output at the start of the operation even if the shift lever 42 has been operated to position N for less than a predetermined holding period Phld[ms] described later. The lever operation determination unit 94 determines whether or not the shift lever 42 that has been operated to position N has been held for a predetermined holding period Phld or longer, that is, whether or not a short-term N operation has been performed. For example, the predetermined holding period Phld is several + [ms] to several hundred [ms].

[0036] When the lever operation determination unit 94 outputs N operation information, the braking force control unit 96 starts regenerative torque reduction control. That is, regenerative torque reduction control starts from the moment the shift lever 42 is operated to the N position. "Regenerative torque reduction control" refers to a control in braking force coordinated control that gradually reduces the regenerative torque Tmg and gradually increases the wheel brake torque Twb. In other words, in regenerative torque reduction control, the vehicle braking torque TB is set to a braking force of a magnitude corresponding to the brake operation amount Bra, while the regenerative torque Tmg is gradually reduced and the wheel brake torque Twb is gradually increased. Note that "regenerative torque reduction control" corresponds to "braking force coordinated control that gradually reduces regenerative torque and gradually increases wheel brake torque" in the present invention.

[0037] If the lever operation determination unit 94 determines that a short-term N operation has been performed, the braking force control unit 96 determines whether a predetermined control period Pctrl [ms] has elapsed since the output of the N operation information, and executes regenerative torque reduction control for the predetermined control period Pctrl. The "predetermined control period Pctrl" is the execution period of regenerative torque reduction control that is experimentally or design-predetermined so that the discomfort felt by the driver due to the shock associated with switching the shift range from D range to N range is within a predetermined acceptable range, and is a longer period than a predetermined holding period Phld. Since the predetermined control period Pctrl is a longer period than the predetermined holding period Phld, a sufficient period can be set as the execution period of regenerative torque reduction control. The wheel brake control unit 96a controls the wheel brake device 26 so that the wheel brake torque Twb is assigned by the regenerative torque reduction control. The regenerative torque control unit 96b controls the MG torque Tmg (<0) of the electric motor MG so that the regenerative torque Tmg is assigned by the regenerative torque reduction control.

[0038] When the predetermined control period Pctrl has elapsed, the regenerative torque Tmg will be less than or equal to a predetermined torque judgment value Tmg_jdg. The predetermined torque judgment value Tmg_jdg is the judgment value for regenerative torque Tmg at which the shock associated with switching the shift range from D range to N range falls within a predetermined allowable range. The smaller the regenerative torque Tmg, the less twisting of the axle etc. due to the regenerative torque Tmg. If the twisting of the axle etc. is small, even if the shift range is switched from D range to N range and the twisting of the axle etc. due to the regenerative torque Tmg is suddenly released, shock is less likely to occur. The twisting of the axle etc. due to the regenerative torque Tmg is the twisting of the power transmission path PT due to the regenerative torque Tmg.

[0039] After the regenerative torque reduction control is performed for a predetermined control period Pctrl, the range switching request unit 98 outputs an N switching request signal, which is a control signal requesting that the shift range be switched to the N range. When the range switching request unit 98 outputs an N switching request signal, the power transmission control unit 92b switches the automatic transmission 22 to the N range. As a result, the shift range becomes the N range, in which power transmission to the pair of drive wheels 14 is cut off.

[0040] Furthermore, if the lever operation determination unit 94 outputs N operation information but determines that a short-term N operation has not occurred, the braking force control unit 96 will cancel the regenerative torque reduction control that was started, and the range switching request unit 98 will not output an N switching request signal. In other words, the shift range will not be switched to the N range, and the D range will be maintained.

[0041] Figure 2 is an example of a flowchart illustrating the control operation of the electronic control unit 90 shown in Figure 1. The flowchart in Figure 2 is repeatedly executed when the vehicle is driving with the shift range in D range and regenerative control is in progress.

[0042] First, in step S10 (hereinafter, "step" will be omitted), which corresponds to the function of the lever operation determination unit 94, it is determined whether or not the shift lever 42 has been moved to the N position. If the determination in S10 is YES, then in S20, which corresponds to the function of the lever operation determination unit 94, N operation information is output. After the execution of S20, in S30, which corresponds to the function of the braking force control unit 96, regenerative torque gradual reduction control is started.

[0043] After the execution of S30, step S40, which corresponds to the function of the lever operation determination unit 94, determines whether a short-term N operation has been performed. If the determination of S40 is YES, step S50, which corresponds to the function of the braking force control unit 96, determines whether a predetermined control period Pctrl has elapsed since the output of the N operation information. If the determination of S50 is NO, S50 is executed again. If the determination of S50 is YES, an N switching request signal is output in S60, which corresponds to the function of the range switching request unit 98. After the execution of S60, in S70, which corresponds to the function of the power transmission control unit 92b, the shift range is switched to the N range by switching the automatic transmission 22 to the N range. If the determination of S40 is NO, in S80, which corresponds to the function of the braking force control unit 96, the regenerative torque reduction control started in S30 is canceled. If the determination of S10 is NO, after the execution of S70 and after the execution of S80, the process returns.

[0044] Figure 3 is an example of a time chart when the flowchart in Figure 2 is executed. In Figure 3, the horizontal axis represents time t [ms].

[0045] Prior to time t1, the vehicle 10 is driving in the D range and regenerative braking is in progress. For example, the accelerator opening θacc is zero, the brake operation amount Bra is constant (>0), and the state of the automatic transmission 22 is in the D range. As a result, the regenerative torque Tmg is controlled to a predetermined torque value Tmg1, and the wheel brake torque Twb is controlled to a predetermined torque value Twb1.

[0046] At time t1, the driver operates the shift lever 42 from the "H position" to the "N position". At time t3 (>t1), the driver releases the shift lever 42, and the shift lever 42 returns to the "H position". That is, during the period from time t1 to time t3, the shift lever 42 is held at the "N position", and the lever position signal Slev becomes a signal representing the "N position". The period from time t1 to time t3 is longer than a predetermined holding period Phld. The switching delay signal for delaying the switching timing of the shift range switches from an off state to an on state at time t1, and switches from the on state to the off state at time t5 (=t1 + Pctrl) which is delayed by a predetermined control period Pctrl from time t1.

[0047] When the shift lever 42 is operated to the "N position" at time t1, the regenerative torque gradual reduction control is started, and the regenerative torque Tmg is gradually reduced from a predetermined torque value Tmg1, and the wheel brake torque Twb is gradually increased from a predetermined torque value Twb1. Time t2 is the time when a predetermined holding period Phld has elapsed from time t1. During the period from time t2 (=t1 + Phld) to time t3, a short-term N operation determination signal indicating that the shift lever 42 is held at the "N position" for a predetermined holding period Phld or more is turned on. When the short-term N operation determination signal is turned on, the regenerative torque gradual reduction control is executed until time t5. For example, at time t4 (<t5) before time t5, the regenerative torque Tmg becomes a zero value that is less than or equal to a predetermined torque determination value Tmg_jdg, and the wheel brake torque Twb becomes the sum (=Twb1 + Tmg1 <0) of the predetermined torque value Twb1 and the predetermined torque value Tmg1.

[0048] At time t5, when the switching delay signal switches from the ON state to the OFF state, an N switching request signal is output, which causes the shift range control signal (for example, the shift control signal Sat that controls the automatic transmission 22 to the neutral state) to switch from the D range to the N range, and the transmission status signal is switched from the D range to the N range. The transmission status signal is a signal that represents the power transmission state in the automatic transmission 22. When the transmission status signal is in the D range, the automatic transmission 22 is in a state that allows the vehicle 10 to move forward. When the transmission status signal is in the N range, the automatic transmission 22 is in a neutral state with power transmission to the vehicle 10 cut off. When the transmission status signal switches from the D range to the N range, the automatic transmission 22 is set to the neutral state.

[0049] According to this embodiment, when the vehicle is driving in the D range and regenerative control is in progress, if the shift lever 42 is held in the N position for a predetermined holding period Phld or longer, regenerative torque reduction control is performed for a predetermined control period Pctrl, and then the shift range is switched to the N range. In this way, the regenerative torque Tmg is gradually reduced by the regenerative torque reduction control performed for a predetermined control period Pctrl. After the predetermined control period Pctrl has elapsed, the twisting of the power transmission path PT due to the regenerative torque Tmg is sufficiently reduced, so even when the shift range is switched to the N range, the occurrence of shock is suppressed. Therefore, even if the shift lever is operated to the N position for a short period of time, the shift range is switched to the N range while the occurrence of shock is suppressed.

[0050] In this embodiment, regenerative torque reduction control is initiated from the moment the shift lever 42 is operated to the N position. In this way, since regenerative torque reduction control is initiated before it is confirmed that a short-term N operation has occurred, it is possible to shorten the predetermined control period Pctrl by the predetermined holding period Phld. This suppresses the delay in switching the shift range to the N range during a short-term N operation.

[0051] In this embodiment, if the shift lever 42 is operated to the N position but is not held in the N position for a predetermined holding period Phld or longer, the regenerative torque reduction control that started from the moment the shift lever 42 was operated to the N position is canceled. The predetermined holding period Phld is a shorter period than the predetermined control period Pctrl. If the shift lever 42 is not held in the N position for a predetermined holding period Phld or longer, the regenerative torque reduction control is only performed for the short period of the predetermined holding period Phld. As a result, after the regenerative torque reduction control is canceled, regenerative control is more likely to be performed in which the regenerative torque Tmg is greater than the wheel brake torque Twb.

[0052] In this embodiment, the predetermined control period Pctrl is a fixed period determined in advance such that the shock associated with switching the shift range from D range to N range remains within a predetermined allowable range. By setting the predetermined control period Pctrl to a fixed period, the reduction of regenerative torque Tmg is ensured, and the complexity of the control is suppressed compared to an embodiment in which the predetermined control period Pctrl is changed according to, for example, the magnitude of the regenerative torque Tmg immediately before a short-term N operation is performed.

[0053] 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.

[0054] In the above-described embodiment, a scenario was described in which the shift range was the D range, BEV driving was in progress, and a short N operation of the shift lever 42 was performed during regenerative control. However, the present invention is also applicable, for example, when the shift range is the R range instead of the D range. In this case, the R range corresponds to the "driving range" in the present invention.

[0055] In the above-described embodiment, the regenerative torque reduction control was initiated when the shift lever 42 was operated to the N position, but the present invention is not limited to this. For example, the regenerative torque reduction control may be initiated when it is determined that a short-term N operation has been performed. Also, in the above-described embodiment, the regenerative torque reduction control was discontinued at S80 in the flowchart of Figure 2, but the present invention is not limited to this. For example, the regenerative torque reduction control may be continued without being discontinued, or braking force coordinated control may be performed to gradually increase the regenerative torque Tmg and gradually decrease the wheel brake torque Twb, so that the regenerative torque Tmg and wheel brake torque Twb are returned to the state at the start of execution in S30.

[0056] In the above-described embodiment, the predetermined control period Pctrl was a predetermined fixed period during which the shock associated with switching the shift range from D range to N range falls within a predetermined allowable range. However, the present invention is not limited to this. For example, the predetermined control period Pctrl may be a period during which the regenerative torque Tmg falls below a predetermined torque determination value Tmg_jdg, during which the shock associated with switching the shift range from D range to N range falls within a predetermined allowable range (see Figure 3). In this embodiment, regenerative torque reduction control is performed during the period during which the regenerative torque Tmg falls below a predetermined torque determination value Tmg_jdg. As a result, the regenerative torque reduction control is performed for a necessary and sufficient period, thereby suppressing the occurrence of shocks while preventing excessive delay in switching to the N range.

[0057] In the above-described embodiment, the brake operation amount Bra was a constant value (>0) in the time chart of Figure 3, but the present invention is not limited to this. For example, the present invention is also applicable to the embodiment where the brake operation amount Bra is zero. Furthermore, the present invention is also applicable to the embodiment where the brake operation amount Bra changes. In the embodiment where the brake operation amount Bra changes, the regenerative torque reduction control is performed such that the vehicle braking torque TB is set to a braking force of a magnitude corresponding to the changing brake operation amount Bra, while the regenerative torque Tmg is gradually reduced and the wheel brake torque Twb is gradually increased.

[0058] In the above-described embodiment, a configuration in which the shift lever 42 is operated for a short period of time in the D range and during BEV driving while regenerative control is in progress was explained, but the present invention is not limited to this configuration. For example, the present invention is also applicable to a configuration in which the shift lever 42 is operated for a short period of time in the D range and during engine driving while regenerative control is in progress. In this configuration, for example, at the time the shift lever 42 is operated for a short period of time, the engine torque Te, which is the engine brake, the regenerative torque Tmg, and the wheel brake torque Twb act as braking forces, and after a predetermined control period Pctrl in which regenerative torque gradual reduction control (i.e., braking force coordinated control that gradually reduces the regenerative torque Tmg and gradually increases the wheel brake torque Twb) is performed, the automatic transmission 22 is switched from the D range to the N range.

[0059] In the above-described embodiment, switching the shift range to the N range was achieved by setting the automatic transmission 22 to the N range, but the present invention is not limited to this embodiment. For example, if the vehicle 10 is equipped with a starting clutch instead of a torque converter 20 in the vehicle configuration of the above-described embodiment, switching to the N range may be achieved by disengaging the starting clutch (=disconnected state), thereby interrupting the power transmission path PT and setting the shift range to the N range. For example, if the vehicle 10 is not equipped with an engine 12 and clutch K0 in the vehicle configuration of the above-described embodiment, switching to the N range may be achieved by setting the electric motor MG to a non-driven state (=free-spinning state) and setting the shift range to the N range. [Explanation of symbols]

[0060] 10: Vehicle, 42: Shift lever (operator), 90: Electronic control unit (control unit), Bra: Brake operation amount, Pctrl: Predetermined control period (predetermined second period), Phld: Predetermined holding period (predetermined first period), TB: Vehicle braking torque, Tmg: MG torque (regenerative torque), Tmg_jdg: Predetermined torque judgment value, Twb: Wheel brake torque

Claims

1. A control device for a vehicle equipped with an automatic resetting control element operated to switch the shift range, If, while the vehicle is traveling in the driving range and regenerative control is in progress, the operator is held in the N position for selecting the N range for a predetermined first period of time or longer, then a braking force coordinated control is performed for a predetermined second period, gradually decreasing the regenerative torque and gradually increasing the wheel brake torque, after which the shift range is switched to the N range. A vehicle control device characterized by the following features.

2. The braking force coordinated control starts from the moment the operator is moved to the N position. The vehicle control device according to feature 1.

3. If the operator is not held in the N position for a predetermined first period of time or longer, the braking force coordinated control that was started from the time the operator was operated to the N position is terminated. The vehicle control device according to feature 2.

4. The aforementioned predetermined second period is a predetermined period during which the shock associated with switching the shift range from the driving range to the neutral range falls within a predetermined acceptable range. A vehicle control device according to any one of claims 1 to 3.

5. The predetermined second period is the period during which the shock associated with switching the shift range from the driving range to the N range falls within a predetermined allowable range, and the regenerative torque falls below a predetermined torque determination value. A vehicle control device according to any one of claims 1 to 3.

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