Vehicle driving assistance device

Abstract

To provide a driving support device of a vehicle which does not impair fuel consumption of a vehicle, even if automatic driving performing acceleration and deceleration is continued so that set vehicle speed can be obtained within a constant vehicle speed range, in a state in which any one of start and stop of an engine is impossible.SOLUTION: On condition that an engine 12 is stopped in acceleration request or the engine 12 is operated in deceleration request by a pulse and glide travel prohibition part 96, pulse and glide travel is prohibited, in a state in which the pulse and glide travel is prohibited by the pulse and glide travel prohibition part 96, when an operation state of the engine 12 is switched, prohibition of the pulse and glide travel is released by a pulse and glide travel prohibition release part 98. Thus, in a state in which the operation state of the engine 12 is switched, the prohibition of the pulse and glide travel is released, the pulse and glide travel is restarted and continued, which suppresses deterioration in fuel consumption.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vehicle driving assistance device, and in particular to a technology that enables high energy efficiency and good fuel economy in automatic driving (hereinafter also referred to as pulse and glide driving or pulse driving) that accelerates and decelerates to obtain a set vehicle speed within a certain vehicle speed range. [Background technology]

[0002] Patent Document 1 proposes a driving assistance device that includes a first constant speed control that automatically adjusts the vehicle acceleration based on a first vehicle speed range that includes a set vehicle speed so that the vehicle speed is maintained at the set vehicle speed, and a second constant speed control that automatically adjusts the vehicle acceleration based on a second vehicle speed range that includes the set vehicle speed so that the vehicle speed is maintained at the set vehicle speed, the second vehicle speed range being set to a range wider than the first vehicle speed range, and that switches between the first constant speed control and the second constant speed control depending on the driving state of the vehicle.

[0003] Generally, when controlling vehicle speed to a specific value, controlling the vehicle speed while allowing a wide range of vehicle speed fluctuations increases the degree of freedom in controlling the operation of a drive device that outputs driving force to the vehicle, and improves energy efficiency. Therefore, the driving assistance device of Patent Document 1 executes a first constant speed control based on a first vehicle speed range in which the allowable range of vehicle speed fluctuations is relatively narrow, and a second constant speed control based on a second vehicle speed range in which the allowable range of vehicle speed fluctuations is relatively wide, so that the vehicle can be driven while controlling the vehicle speed to a set vehicle speed with higher energy efficiency. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-0953320 Summary of the Invention [Problem to be solved by the invention]

[0005] The first constant speed control and second constant speed control in the driving assistance device of Patent Document 1 accelerate and decelerate the vehicle so that a set vehicle speed is achieved within a certain vehicle speed range. For example, during acceleration, a driving force that improves energy efficiency is required, assuming the engine is running, and during deceleration, a driving force that improves energy efficiency is required, assuming the engine is stopped. For this reason, this control is only valid when both the engine can be started and stopped. Continuing the control when either the engine cannot be started or stopped has the disadvantage of worsening the vehicle's fuel efficiency.

[0006] The present invention has been made against the background of the above circumstances, and its purpose is to provide a vehicle driving assistance device that does not impair the fuel efficiency of the vehicle even when the vehicle continues to drive automatically by accelerating and decelerating so as to obtain a set vehicle speed within a certain vehicle speed range, even when it is not possible to start or stop the engine. [Means for solving the problem]

[0007] The gist of the first invention is that it includes: (a) a driving assistance device for a vehicle equipped with a prime mover including an engine, which performs automatic driving by accelerating and decelerating so as to obtain a set vehicle speed within a certain vehicle speed range, (b) a palgra driving prohibition unit that prohibits automatic driving by accelerating and decelerating so as to obtain a set vehicle speed within the certain vehicle speed range, on the condition that the engine is stopped when an acceleration request is made or the engine is operating when a deceleration request is made, and (c) a palgra driving prohibition release unit that releases the prohibition of automatic driving by accelerating and decelerating so as to obtain a set vehicle speed within the certain vehicle speed range when the operating state of the engine is switched to a side where the condition is not met, while the palgra driving prohibition unit has prohibited automatic driving by accelerating and decelerating so as to obtain a set vehicle speed within the certain vehicle speed range.

[0008] The gist of the second invention is that it includes (d) an engine start / stop control unit that commands the start of the engine when the required driving force is equal to or greater than a judgment threshold set for determining whether the engine should be running or stopped, and commands the stop of the engine when the required driving force is below the judgment threshold set for determining whether the engine should be running or stopped, and (e) a judgment threshold change unit that changes the judgment threshold so that the engine can be more easily switched between starting and stopping when the Pargra driving prohibition unit prohibits automatic driving that accelerates and decelerates to obtain a set vehicle speed within the certain vehicle speed range. [Effects of the Invention]

[0009] According to the first aspect of the present invention, the Palgra travel prohibition unit prohibits Palgra travel (automated travel in which acceleration and deceleration are performed to obtain a set vehicle speed within the certain vehicle speed range) on the condition that the engine is stopped when an acceleration request is made or the engine is operating when a deceleration request is made, and if the operating state of the engine is switched while the Palgra travel prohibition unit has prohibited automatic travel in which acceleration and deceleration are performed to obtain a set vehicle speed within the certain vehicle speed range, the Palgra travel prohibition release unit releases the prohibition of Palgra travel. In this way, when the operating state of the engine is switched, the prohibition of automatic travel in which acceleration and deceleration are performed to obtain a set vehicle speed within the certain vehicle speed range is released, and the automatic travel is resumed and continued, thereby suppressing deterioration of fuel economy.

[0010] According to the second aspect of the present invention, when the Palgra traveling prohibition unit prohibits Palgra traveling, the judgment threshold change unit changes the judgment threshold so that the engine can be easily switched between start and stop. That is, if the engine is running during the Palgra traveling prohibition state, the power value of the judgment threshold is increased so that the engine can be easily stopped, and if the engine is stopped, the power value of the judgment threshold is decreased so that the engine can be easily started. The judgment threshold is changed so that the engine can be easily switched between start and stop. This allows the vehicle to immediately return to Palgra traveling when other causes preventing the engine from running or stopping are resolved, thereby expanding energy-efficient traveling. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram illustrating the main parts of a control system of a vehicle to which the present invention is applied, and shows the main parts of the control functions of an electronic control device included in the control system as a functional block diagram. [Figure 2] 2 is a time chart illustrating a control function of a first constant speed control section (normal constant speed control section) provided in the electronic control device of FIG. [Figure 3] 2 is a time chart illustrating a control function of a second constant speed control section (eco constant speed control section) provided in the electronic control device of FIG. [Figure 4] 2 is a diagram showing the energy efficiencies of the engine and the electric motor provided in the vehicle of FIG. 1 on an axis indicating the required driving force. [Figure 5] 4 is a flowchart illustrating the main control operations of a Palgra traveling prohibition unit and a Palgra traveling prohibition release unit in the electronic control device of FIG. 1. [Figure 6] 2 is a flowchart illustrating a main part of the control function of a determination threshold value changing unit in the electronic control device of FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0012] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a hydraulic circuit control device for a vehicle transmission according to the present invention will now be described in detail with reference to the accompanying drawings. [Example]

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a diagram illustrating the schematic configuration of a drive system of a vehicle 10 equipped with an electronic control device 90 as a control device according to one embodiment of the present invention, and also illustrates the main parts of control functions and control systems for various controls in the vehicle 10. The vehicle 10 is a hybrid electric vehicle equipped with an engine 12 and an electric motor MG as a drive system (power source). The vehicle 10 includes the engine 12, drive wheels 14, which are either left or right rear wheels or front wheels, and a power transmission device 18 provided in a power transmission path between the engine 12 and the drive wheels 14. The engine 12 is an internal combustion engine such as a gasoline engine or a diesel engine. The engine 12 has an engine control device 22, which includes a throttle actuator, a fuel injection device, an ignition device, etc., controlled by the electronic control device 90, thereby controlling the engine torque Te of the engine 12. The electric motor MG is a rotating electric machine that functions as a motor that generates mechanical power from electric power and as a generator that generates electric power from mechanical power, and is a so-called motor-generator. The electric motor MG is connected to a high-voltage HEV (Hybrid Electric Vehicle) battery 28 via a PCU (Power Control Unit) 24 having an inverter and the like. The PCU (Power Control Unit) 24 of the electric motor MG is controlled by an electronic control device 90, thereby controlling the MG torque Tmg of the electric motor MG. The HEV battery 28 is an electricity storage device that supplies power to the electric motor MG.

[0014] The power transmission device 18 includes a K0 clutch 34, a WSC clutch 36, and an automatic transmission 38 arranged in series from the engine 12 side within a case 32, which is a non-rotating member attached to the vehicle body, and power is transmitted from a transmission output shaft 40 to the drive wheels 14 via a differential gear 42, a pair of drive shafts 44, etc. The K0 clutch 34 is an engagement device that connects and disconnects the engine 12 and the electric motor MG, and is an engine connect / disconnect clutch that disconnects the engine 12 from the power transmission path. The WSC clutch 36 is an engagement device that connects and disconnects the electric motor MG and the drive wheels 14, and functions as a starting clutch and an input clutch by being controlled for slip engagement by an electronic control device 90.

[0015] The power transmission device 18 includes an engine connecting shaft 46 that connects the engine 12 and the K0 clutch 34, and an electric motor connecting shaft 48 that connects the K0 clutch 34 and the WSC clutch 36, with the electric motor MG connected to the electric motor connecting shaft 48 so as to be able to transmit power. The K0 clutch 34 and the WSC clutch 36 are both wet or dry friction engagement devices formed of multi-plate or single-plate clutches pressed by hydraulic actuators, and their control states, such as engaged and disengaged states, are switched by an electronic control device 90. An input member of the WSC clutch 36 is connected to the electric motor connecting shaft 48, and an output member of the WSC clutch 36 is connected to a transmission input shaft 50, which is an input rotating member of the automatic transmission 38.

[0016] The automatic transmission 38 is a known planetary gear automatic transmission that includes, for example, multiple planetary gear devices and multiple engagement devices CB. The engagement devices CB are hydraulic friction engagement devices that include, for example, multiple-plate or single-plate clutches or brakes pressed by a hydraulic actuator, or band brakes tightened by a hydraulic actuator. The automatic transmission 38 is a stepped transmission in which one of multiple gear stages Gr with different gear ratios γat (=input rotation speed Ni / output rotation speed No) is formed by engaging one of the engagement devices CB.

[0017] The vehicle 10 is equipped with a mechanical oil pump 58 and an electric oil pump 60. The mechanical oil pump 58 is driven to rotate by at least one of the engine 12 and the electric motor MG, and discharges hydraulic oil used in the power transmission device 18. The electric oil pump 60 is driven to rotate by a dedicated pump drive motor 62, and can discharge hydraulic oil at any timing, including when the vehicle 10 is stopped. The hydraulic oil discharged from the mechanical oil pump 58 and the electric oil pump 60 is supplied to the hydraulic control circuit 52 as a source pressure. The hydraulic control circuit 52 outputs the regulated CB hydraulic pressure PRcb, K0 hydraulic pressure PRk0, WSC hydraulic pressure PRwsc, etc.

[0018] The vehicle 10 is equipped with an electronic control device 90 as a control device that executes various types of control. The electronic control device 90 includes a so-called microcomputer equipped with, for example, a CPU, RAM, ROM, an input / output interface, etc., and executes various types of control of the vehicle 10. The electronic control device 90 includes multiple computers for engine control, MG control, hydraulic control, etc., as needed.

[0019] The electronic control unit 90 receives signals related to various information required for various controls, such as engine speed Ne (the rotational speed of the engine 12), input rotational speed Ni, output rotational speed No corresponding to vehicle speed V, MG rotational speed Nmg (the rotational speed of the electric motor MG), accelerator pedal position θacc (the amount of operation of the accelerator pedal or the like indicating the amount of output required by the driver), throttle valve position θth (the opening of the electronic throttle valve), power switch press signal Spw, cruise assist command signal Sda, and eco-drive command signal Sec, from, for example, the engine speed sensor 70, input rotational speed sensor 72, output rotational speed sensor 74, MG rotational speed sensor 76, accelerator pedal position sensor 80, throttle valve position sensor 82, power switch 84, cruise assist operation device 86, and eco-drive operation device 88. The power switch 84 is an automatic reset push button switch located near the driver's seat, and outputs a power switch press signal Spw when pressed by the driver at the start or end of driving the vehicle 10.

[0020] The electronic control device 90 outputs an engine control command signal Se for controlling the engine 12, an MG control command signal Smg for controlling the electric motor MG, an electric oil pump control command signal Seop for controlling the electric oil pump 60, a CB hydraulic control command signal Sbc for controlling the engagement device CB, a K0 hydraulic control command signal Sk0 for controlling the K0 clutch 34, a WSC hydraulic control command signal Swsc for controlling the WSC clutch 36, and the like to various devices provided in the vehicle 10, such as the engine control device 22, the PCU 24, and the hydraulic control circuit 52. The hydraulic control circuit 52 is provided with various solenoid valves that switch oil paths and control hydraulic pressure in accordance with the K0 hydraulic control command signal Sk0, the CB hydraulic control command signal Sbc, and the WSC hydraulic control command signal Swsc.

[0021] The electronic control device 90 is equipped with a power source control unit 92 and also functions as a driving assistance control unit, and functionally includes a Palgra running control unit 94, a Palgra running prohibition unit 96, a Palgra running prohibition release unit 98, an engine start / stop control unit 100, a judgment threshold change unit 102, etc.

[0022] The power source control unit 92 calculates the driver's required driving force (required power, required driving amount) Pdreq for the vehicle 10, for example, by applying the accelerator opening θacc and the vehicle speed V to a required driving amount map. The required driving amount map is a relationship for calculating the required driving amount that is determined in advance experimentally or by design and stored. The required driving force Pdreq [N] is, for example, a required driving torque Trdem [Nm] at the drive wheels 14 or a required driving power Prdem [W]. The power source control unit 92 calculates a required input torque Tidem at the transmission input shaft 50 that can achieve the required driving force Pdreq, and determines a target engine torque Tetgt and a target MG torque Tmtgt that will achieve the required input torque Tidem. The power source control unit 92 then outputs an engine control command signal Se that controls the engine 12 so that the target engine torque Tetgt is output, and outputs an MG control command signal Smg that controls the electric motor MG so that the target MG torque Tmtgt is output.

[0023] For example, if the required input torque Tidem can be satisfied only with the output of the electric motor MG, the power source control unit 92 selects a BEV (Battery Electric Vehicle) driving mode, which is a motor driving mode in which the electric motor MG is driven only by power from the HEV battery 28. In the BEV driving mode, the K0 clutch 34 is disengaged to stop the engine 12, and the WSC clutch 36 is engaged to perform BEV driving, which uses only the electric motor MG as a power source. In this BEV driving mode, the MG torque Tmg is controlled to achieve the required input torque Tidem. On the other hand, if the required input torque Tidem cannot be satisfied without using at least the output of the engine 12, the power source control unit 92 selects an HEV driving mode, which is an engine driving mode. In the HEV driving mode, both the K0 clutch 34 and the WSC clutch 36 are engaged to perform engine driving, i.e., HEV driving, in which the vehicle is driven using at least the engine 12 as a power source. In this HEV driving mode, the engine torque Te is controlled to realize all or part of the required input torque Tidem, and the MG torque Tmg is controlled to compensate for the torque that is insufficient in the engine torque Te relative to the required input torque Tidem.

[0024] When the driver operates the driving assistance operation device 86 and driving assistance conditions are met, the Palgra driving control unit 94 performs automatic driving (hereinafter also referred to as pulse and glide driving or Palgra driving) by increasing or decreasing the required driving force Pdreq to achieve the set vehicle speed Vset within a certain vehicle speed range and accelerating and decelerating the vehicle. During acceleration, the engine 12 is operated to utilize the driving force of the engine 12, and during deceleration, the electric motor MG is regenerated to utilize the braking force.

[0025] Specifically, the Palgra travel control unit 94 executes first constant speed control (normal Palgra travel control) that automatically adjusts the acceleration of the vehicle to accelerate and decelerate so as to achieve the set vehicle speed Vset, based on a first vehicle speed range including the set vehicle speed Vset, so that the vehicle speed V is maintained at the set vehicle speed Vset. For example, as shown in FIG. 2, when the vehicle speed V decreases and falls below the set vehicle speed Vset, the vehicle 10 is accelerated to increase the vehicle speed V. Conversely, when the vehicle speed V increases and exceeds the set vehicle speed Vset, the vehicle 10 is decelerated to decrease the vehicle speed V. The Palgra travel control unit 94 calculates a required acceleration Greq so that the speed at which the vehicle speed V of the vehicle 10 converges to the set vehicle speed Vset is equal to or greater than a predetermined speed. The Palgra travel control unit 94 calculates a required driving force Pdreq to achieve the required acceleration Greq, and controls the power source control unit 92 to control the output of the engine 12 and the electric motor MG so that the required driving force Pdreq is output. As a result, acceleration and deceleration are repeated, as shown in FIG. 2. In addition, instead of accelerating and decelerating the vehicle speed V based on the set vehicle speed Vset, the vehicle speed V may be accelerated and decelerated based on exceeding the upper limit value and falling below the lower limit value of a vehicle speed range including the set vehicle speed.

[0026] Furthermore, when the eco-planning support control is selected by operating the eco-travel operating device 88, the Palgra travel control unit 94 executes second constant speed control (eco Palgra travel control) that automatically adjusts the acceleration of the vehicle 10 to accelerate and decelerate to achieve the set vehicle speed Vset, based on a second vehicle speed range including the set vehicle speed Vset, so that the vehicle speed V is maintained at the set vehicle speed Vset. Because the second vehicle speed range is larger than the first vehicle speed range, the acceleration and deceleration cycle is longer than that of the first constant speed control. For example, as shown in FIG. 3 , when the vehicle speed V decreases and falls below a lower limit value Vlow of the second vehicle speed range including the set vehicle speed Vset, the vehicle 10 is accelerated to increase the vehicle speed V until it exceeds an upper limit value Vup. Conversely, when the vehicle speed V increases and exceeds the upper limit value Vup of the second vehicle speed range including the set vehicle speed Vset, the vehicle 10 is decelerated to decrease the vehicle speed V until it falls below the lower limit value Vlow. When accelerating the vehicle 10 under this second constant speed control, the Palgra driving control unit 94 sets the acceleration G as the required acceleration Greq so that the energy efficiency of the drive device of the vehicle 10 is equal to or greater than a predetermined efficiency, taking into account the vehicle speed V at that time.

[0027] In a vehicle 10 equipped with an engine 12 and an electric motor MG as a drive system, as shown in Figure 4, the energy efficiency Eeng (particularly fuel economy) when the engine 12 outputs drive power reaches a maximum value when the drive power output from the engine 12 is a certain value Pda, and the energy efficiency Emg (particularly electricity economy) when the electric motor MG outputs drive power reaches a maximum value when the drive power output from the electric motor MG is a certain value Pdb. Therefore, in Pargra driving, the greater the degree of freedom in control of the engine 12 and electric motor MG that constitute the drive system, the more energy-efficiently the engine 12 and electric motor MG can be operated.

[0028] Generally, when controlling the vehicle speed V to run at a specific set vehicle speed Vset, controlling the vehicle speed while allowing a wide range of vehicle speed fluctuations provides greater control flexibility when controlling the engine 12 and the electric motor MG to output the driving force Pdreq to the vehicle 10. As a result, control that improves energy efficiency can be applied to the control of the engine 12 and the electric motor MG. In this embodiment, a first constant speed control based on a set vehicle speed Vset having a relatively narrow allowable vehicle speed range and a second constant speed control based on a set vehicle speed Vset having a relatively wide allowable vehicle speed range are provided, and the second constant speed control is selectively executed depending on the running state of the vehicle 10. This allows the vehicle 10 to run with higher energy efficiency while controlling the vehicle speed V of the vehicle 10 to be close to the set vehicle speed Vset.

[0029] The Palgravity traveling prohibition unit 96 prohibits Palgravity traveling by the Palgravity traveling control unit 94, i.e., automatic traveling that accelerates and decelerates so as to obtain the set vehicle speed Vset within a certain vehicle speed range, when this prohibition condition is met. By prohibiting Palgravity traveling by this Palgravity traveling prohibition unit 96, it is possible to avoid continuing Palgravity traveling control in situations where performing Palgravity traveling would actually worsen fuel economy.

[0030] When the operating state of the engine 12 is switched to a side where the prohibition condition is not satisfied while Palgravure driving is prohibited by the Palgravure driving prohibition unit 96, the Palgravure driving prohibition release unit 98 releases the prohibition of Palgravure driving, i.e., the prohibition of automatic driving that accelerates and decelerates so as to obtain a set vehicle speed within a certain vehicle speed range. When it is confirmed that the prohibition condition for Palgravure driving is not satisfied, i.e., that the engine 12 can both be started and stopped, the Palgravure driving prohibition release unit 98 can release the prohibited state of Palgravure driving, thereby avoiding an uncomfortable feeling in drivability that changes in a short period of time due to hunting between Palgravure driving and constant speed cruise control (while Palgravure driving is prohibited).

[0031] The engine start / stop control unit 100 commands the engine 12 to start when the required driving force Pdreq during Palgra driving by the Palgra driving control unit 94 becomes equal to or greater than a judgment threshold Pdreq1 set for determining whether the engine 12 is operating or stopped, and commands the engine 12 to stop when the required driving force Pdreq becomes lower than the judgment threshold Pdreq1 set for determining whether the engine 12 is operating or stopped.

[0032] When the Palgravity traveling prohibition unit 96 prohibits Palgravity traveling by the Palgravity traveling control unit 94, i.e., automatic traveling that accelerates and decelerates so as to obtain the set vehicle speed Vset within a certain vehicle speed range, the determination threshold changing unit 102 changes the determination threshold Pdreq1 to make it easier to switch between starting and stopping the engine 12. For example, when the engine 12 is running, the determination threshold changing unit 102 changes the determination threshold Pdreq1 to a higher value compared to when Palgravity traveling is not prohibited by the Palgravity traveling prohibition unit 96 so as to make it easier to stop the engine 12. Furthermore, when the engine 12 is stopped, the determination threshold changing unit 102 changes the determination threshold Pdreq1 to a lower value compared to when Palgravity traveling is not prohibited by the Palgravity traveling prohibition unit 96 so as to make it easier to start the engine 12. During the period when Palgra traveling is prohibited by Palgra traveling prohibition unit 96, constant speed control (cruise control) is performed at a constant speed, so the change in required driving force is small and the frequency of switching between operation and stop of engine 12 is low, making it expected that the conditions for canceling the Palgra traveling prohibition state will be difficult to meet. However, by changing the determination threshold Pdreq1 by this determination threshold change unit 102, such conditions for canceling the Palgra traveling prohibition state can be easily met. As a result, Palgra traveling can be immediately resumed when other causes preventing the operation or stop of engine 12 are resolved, making it possible to expand efficient traveling with high energy efficiency.

[0033] 5 and 6 are flowcharts explaining the main control operations of the electronic control unit 90, with FIG. 5 showing the Palgra travel prohibition permission control routine and FIG. 67 showing the engine start / stop threshold change control routine.

[0034] In step S1 of FIG. 5 (hereinafter, "step" will be omitted), it is determined whether or not Palgravity driving control is in progress. If the determination in S1 is affirmative, it is determined in S2 whether or not Palgravity driving is permitted. If the determination in S2 is affirmative, it is determined in S3 whether or not acceleration for Palgravity driving is being requested. If the determination in S3 is affirmative, acceleration for Palgravity driving is being requested, so it is determined in S4 whether or not the engine 12 is stopped. If the determination in S4 is affirmative, the engine 12 is stopped during the period during which acceleration for Palgravity driving is requested, so Palgravity driving is prohibited in S5 corresponding to the Palgravity driving prohibition unit 96. If the determination in S4 is negative, the engine 12 is operating during the acceleration request for Palgravity driving, so Palgravity driving continues and this routine is terminated.

[0035] If the determination in S3 is negative, it means that deceleration is being requested, not acceleration, for Palgravity travel, so a determination is made in S6 as to whether the engine 12 is operating. If the determination in S6 is positive, it means that the engine 12 is operating during deceleration, not acceleration, for Palgravity travel, so Palgravity travel is prohibited in S7, which corresponds to the Palgravity travel prohibition unit 96.

[0036] If the determination in S2 is negative, then in S8 it is determined whether the engine 12 was operating in the previous control cycle. If the determination in S8 is positive, then in S9 it is determined whether the engine 12, which was operating in the previous control cycle, is stopped in the current control cycle. If the determination in S9 is positive, then in S10, which corresponds to the Palgrave driving prohibition release unit 98, the prohibition on Palgrave driving is lifted and Palgrave driving is permitted. If the determination in S9 is negative, then the engine 12 is operating in the current control cycle as well as in the previous control cycle, so the prohibition on Palgrave driving continues and this routine is terminated.

[0037] If the determination in S8 is negative, the engine 12 was stopped in the previous control cycle while Palgravity driving was prohibited, so in S11 it is determined whether the engine 12 is operating in the current control cycle. If the determination in S11 is positive, the engine 12, which was stopped in the previous control cycle, is operating in the current control cycle, so the prohibition of Palgravity driving is lifted in S12, which corresponds to the Palgravity driving prohibition release unit 98, and Palgravity driving is permitted. If the determination in S11 is negative, the engine 12, which was operating in the previous control cycle, is stopped in the current control cycle, so Palgravity driving is continued and this routine is terminated.

[0038] In S20 of FIG. 6, a determination threshold Pdreq1 is calculated to determine whether the engine 12 is being operated to provide the required driving force Pdreq corresponding to an acceleration request that assumes the engine 12 is operating during Palgravity driving. Next, in S21, the Palgravity driving prohibition unit 96 determines whether Palgravity driving is prohibited. If the determination in S21 is negative, the routine is terminated. If the determination in S21 is positive, however, in S22, it is determined whether the engine 12 is stopped. If the determination in S22 is positive, the engine 12 is stopped. In S23, which corresponds to the determination threshold change unit 102, the determination threshold Pdreq1 is changed to a lower value than when Palgravity driving is not prohibited by the Palgravity driving prohibition unit 96, so that the engine 12 can be started more easily. However, if the judgment in S22 is negative, in S23 corresponding to the judgment threshold change unit 102, since the engine 12 is running, the judgment threshold Pdreq1 is changed to a higher value than when palgra traveling is not prohibited by the palgra traveling prohibition unit 96 so that the engine 12 can be easily stopped.

[0039] As described above, according to the electronic control device 90 of this embodiment, the Palgravity traveling prohibition unit 96 prohibits Palgravity traveling (automated traveling in which acceleration and deceleration are performed to obtain a set vehicle speed within the certain vehicle speed range) on the condition that the engine 12 is stopped when acceleration is requested or that the engine 12 is operating when deceleration is requested, and if the operating state of the engine 12 is switched while Palgravity traveling is prohibited by the Palgravity traveling prohibition unit 96, the Palgravity traveling prohibition release unit 98 releases the prohibition of Palgravity traveling. In this way, when the operating state of the engine 12 is switched, the prohibition of Palgravity traveling is released and Palgravity traveling is resumed and continued, thereby suppressing deterioration of fuel economy.

[0040] Furthermore, according to the electronic control device 90 of this embodiment, when the Palgra driving prohibition unit 96 prohibits Palgra driving (automated driving in which acceleration and deceleration are performed to obtain a set vehicle speed within a certain vehicle speed range), the judgment threshold change unit 102 changes the judgment threshold Pdreq1 to facilitate switching between starting and stopping of the engine 12. That is, while the Palgra driving is prohibited, if the engine 12 is running, the judgment threshold Pdreq1 (power value) is increased to facilitate stopping of the engine 12, and if the engine 12 is stopped, the judgment threshold Pdreq1 (power value) is decreased to facilitate starting of the engine 12. This allows the vehicle to immediately return to Palgra driving when other causes preventing the engine 12 from starting or stopping are resolved, thereby expanding energy-efficient driving.

[0041] Although the present invention has been described in detail above with reference to tables and drawings, the present invention can be embodied in other forms and various modifications can be made without departing from the spirit of the present invention.

[0042] For example, the vehicle 10 in the above-described embodiment is a vehicle equipped with one electric motor (motor generator) MG between the engine 12 and the automatic transmission 38, but is not limited to this. For example, the vehicle may be equipped with a power split device (electric torque converter) and an electric motor between the engine 12 and the automatic transmission 38.

[0043] The above is merely one embodiment, and although other examples will not be given, the present invention can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art within the scope of the present invention. [Explanation of symbols]

[0044] 10: Vehicle 12: Engine MG: Electric motor 90: Electronic control device 92: Power source control unit 94: Pargra driving control unit 96: No-Ride Paragra 98: Pargra Driving Ban Removal Department 100: Engine start control unit 102: Judgment threshold change unit

Claims

1. A driving assistance device for a vehicle that performs automatic driving by accelerating and decelerating the vehicle so as to obtain a set vehicle speed within a certain vehicle speed range, the device comprising: a pargra travel prohibition unit that prohibits automatic travel in which acceleration and deceleration are performed so as to obtain a set vehicle speed within the certain vehicle speed range, on the condition that the engine is stopped when an acceleration request is made or the engine is operating when a deceleration request is made; and a Palgra travel prohibition release unit that, when the operating state of the engine is switched to a side where the condition is not satisfied in a state where the Palgra travel prohibition unit has prohibited the automatic travel of accelerating and decelerating so as to obtain a set vehicle speed within the certain vehicle speed range, releases the prohibition of the automatic travel of accelerating and decelerating so as to obtain a set vehicle speed within the certain vehicle speed range. A vehicle driving assistance device characterized by:

2. an engine start / stop control unit that issues a command to start the engine when the required driving force is equal to or greater than a determination threshold set for determining whether the engine is operating or stopped, and that issues a command to stop the engine when the required driving force is below the determination threshold set for determining whether the engine is operating or stopped; and a determination threshold changing unit that changes the determination threshold so that the engine can be easily switched between starting and stopping when the vehicle is prohibited from automatically accelerating and decelerating so as to obtain a set vehicle speed within the certain vehicle speed range by the vehicle speed prohibiting unit.

2. The vehicle driving assistance device according to claim 1.

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