JP2016094161A - Vehicle control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further increase energy efficiency during coast travelling of a vehicle and/or improve drivability.SOLUTION: A vehicle control device that controls a vehicle equipped with an electric motor capable of imparting rotational drive force to an output shaft or an axle of an internal combustion engine imparts rotational drive force to an output shaft or an axle of an internal combustion engine from an electric motor during coast travelling of a vehicle, and changes the magnitude of the output of the electric motor at that time, or whether or not to impart the rotational drive force from the electric motor according to at least one of a vehicle speed, deceleration of the vehicle or the gradient of a road surface, and a transmission gear ratio of a change gear interposed between the output shaft and the axle of the internal combustion engine.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a control apparatus for a vehicle including an electric motor capable of applying a rotational driving force to an output shaft or an axle of an internal combustion engine.

  2. Description of the Related Art A vehicle is known in which an internal combustion engine serving as a drive source for driving a vehicle axle (and drive wheels) and auxiliary equipment is provided with an electric motor that assists this. This electric motor often has a function as a generator, and can perform regenerative braking when the vehicle decelerates and recover the kinetic energy of the vehicle as electric energy (for example, Patent Document 1 below). And 2).

  In a vehicle equipped with an internal combustion engine, it is known to perform a fuel cut that temporarily stops fuel supply to a cylinder. Generally, when the accelerator pedal depression amount is 0 or less than a threshold value close to 0 and the engine speed is equal to or higher than the fuel cut permission speed, fuel cut is started, that is, fuel injection is interrupted. When one of the conditions such as the accelerator pedal depression amount exceeding the threshold value or the engine speed decreasing to the fuel cut return speed is satisfied, the fuel cut is finished and the fuel injection is restarted.

  In order to further improve the fuel efficiency of the vehicle, it is required to extend the period of coasting (scoiling, inertial running) while maintaining the fuel cut state as long as possible. The vehicle speed and engine speed during coasting gradually decline due to engine brake and drive train losses. In particular, in a vehicle that employs a belt-type continuously variable transmission in the drive system, it is necessary to displace the pulley to the position closest to the low gear before rotation of the pulley that pinches the belt stops. However, if the gear ratio of the transmission is changed to a low gear, the engine braking action is enhanced, the engine speed decreases rapidly with the vehicle speed, the fuel cut end condition is satisfied, and the fuel cut ends earlier. . In addition, the fact that the engine braking action is strong and the vehicle deceleration is unnecessarily high also leads to a decrease in drivability (or a deterioration in drive feeling).

  In view of this, it is considered that the motor is operated during coasting of the vehicle to apply a rotational driving force to the output shaft of the internal combustion engine, and thus to the axle, to execute coast assist that relaxes the deceleration of the vehicle (Patent Document 2 below). See).

JP 2014-101847 A Japanese Patent Laid-Open No. 02-256843

  However, it cannot be said that it is efficient to always execute the coast assist regardless of the current state of the vehicle. As a specific example, while the vehicle speed is high, increasing the output of the electric motor has little effect on the deceleration of the vehicle, and there is still a delay until the engine speed decreases to the fuel cut return speed. Therefore, even if coast assist is executed when the vehicle speed is high, it is considered that the effect of improving the fuel consumption and drivability is poor compared to the power consumption by the electric motor.

  In addition, when the vehicle is located on an uphill road, the deceleration of the vehicle is remarkably large in the first place, and even if coast assist is executed, only power is consumed wastefully. Expected to increase.

  Conversely, if coast assist is executed while the vehicle is on a downhill road, the vehicle feels a jump-out feeling that accelerates, and there is a concern that drivability deteriorates.

  Furthermore, the transmission gear ratio is also involved in the deceleration of the vehicle. When the gear ratio of the transmission is still close to the high gear, the engine braking action becomes relatively small, so it is not always necessary to execute the coast assist.

  An object of the present invention, which has been made by paying attention to the above points for the first time, is to further improve energy efficiency and / or improve drivability during coasting of a vehicle.

  The present invention controls a vehicle equipped with an electric motor capable of applying a rotational driving force to an output shaft or axle of an internal combustion engine, and when the vehicle travels on a coast, the output shaft or axle of the internal combustion engine from the electric motor. Rotation driving force is applied to the motor, the magnitude of the output of the motor at that time or whether or not the rotation driving force is applied from the motor, vehicle speed, vehicle deceleration or road gradient, output of the internal combustion engine The vehicle control device is configured to change in accordance with at least one of the transmission gear ratios interposed between the shaft and the axle.

  ADVANTAGE OF THE INVENTION According to this invention, the energy efficiency at the time of coast driving | running | working of a vehicle can be improved further, and / or improvement of drivability can be aimed at.

The figure which shows schematic structure of the internal combustion engine in one Embodiment of this invention. The figure which shows typically the structure of the connection of the internal combustion engine and generator / motor in the embodiment. The figure which shows the electric circuit of the generator and electric motor in the embodiment. The figure which shows the structure of the drive system of the vehicle in the embodiment. The shift diagram of the continuously variable transmission in the same embodiment. The timing diagram explaining the relationship between the vehicle speed and the base assist level during coasting. The flowchart which shows the example of a procedure of the process which the control apparatus of the embodiment performs according to a program.

  An embodiment of the present invention will be described with reference to the drawings. A vehicle internal combustion engine 100 shown in FIG. 1 is a spark ignition type four-stroke engine and includes a plurality of cylinders 1 (one of which is shown in FIG. 1). In the vicinity of the intake port of each cylinder 1, an injector 11 for injecting fuel is provided. A spark plug 12 is attached to the ceiling of the combustion chamber of each cylinder 1. The spark plug 12 receives spark voltage generated by the ignition coil and causes spark discharge between the center electrode and the ground electrode.

  The intake passage 3 for supplying intake air takes in air from the outside and guides it to the intake port of each cylinder 1. On the intake passage 3, an air cleaner 31, an electronic throttle valve 32, a surge tank 33, and an intake manifold 34 are arranged in this order from the upstream.

  The exhaust passage 4 for discharging the exhaust guides the exhaust generated as a result of burning the fuel in the cylinder 1 from the exhaust port of each cylinder 1 to the outside. An exhaust manifold 42 and an exhaust purification three-way catalyst 41 are disposed on the exhaust passage 4.

  An external EGR (Exhaust Gas Recirculation) device 2 realizes a so-called high-pressure loop EGR. The EGR device 2 includes an external EGR passage 21 that communicates the upstream side of the catalyst 41 in the exhaust passage 4 and the downstream side of the throttle valve 32 in the intake passage 3, an EGR cooler 22 provided on the EGR passage 21, and an EGR passage 21. And an EGR valve 23 that controls the flow rate of the EGR gas flowing through the EGR passage 21. The inlet of the EGR passage 21 is connected to the exhaust manifold 42 in the exhaust passage 4 or a predetermined location downstream thereof. The outlet of the EGR passage 21 is connected to a predetermined location downstream of the throttle valve 32 in the intake passage 3, specifically to a surge tank 33.

  As shown in FIG. 2, the internal combustion engine 100 according to the present embodiment includes a starter motor (cell motor) 140, an ISG (Integrated Starter Generator) that is a generator / motor, or a compressor 130 and other auxiliary machines. Accompanying.

  The starter motor 140 is an electric motor dedicated to cranking that rotates the crankshaft 10 of the internal combustion engine 100 mainly during cold start (the driver operates the ignition switch or the ignition key to start the internal combustion engine 100). The starter motor 140 has a pinion gear 141 on its output shaft, and the pinion gear 141 rotates on the crankshaft 10 by meshing with a ring gear 103 fixed to the crankshaft 10 that is the output shaft of the internal combustion engine 100. Transmits driving force. The pinion gear 141 is detached from the ring gear 103 except when the starter motor 140 is cranking the internal combustion engine 100.

  The ISG 110 has both a function as an electric motor that drives the crankshaft 10 and thus the vehicle axle (and drive wheels) 153, and a function as a generator that receives power from the crankshaft 10 and generates electric power. The ISG 110 is connected to one end side of the crankshaft 10 of the internal combustion engine 100 via the winding transmission mechanisms 112, 113, and 101.

  The ISG 110 is, for example, an inner-rotor type AC synchronous machine, and includes a rotor (rotor) having both permanent magnets and a rotor coil (excitation (field) winding) 116, and a three-phase AC facing the outer peripheral surface of the rotor. A stator (stator) including a stator coil (stator winding) 115 is used as an element. The rotor is fixed to the outer periphery of the rotor shaft 111. Pulleys (or sprockets) 112 and 101 are fixed to the rotor shaft 111 and the crankshaft 10, respectively, and the crankshaft 10 and the rotor shaft are secured by a belt (or chain) 113 wound around the pulleys 112 and 101. The rotational driving force is transmitted to and from 111 (bidirectionally).

  The ISG 110 supplies power from the in-vehicle power storage device 61 mainly when the internal combustion engine 100 that has been idle-stopped is restarted or when the traveling drive force supplied to the axle 153 is increased (particularly during acceleration or climbing). In response, the crankshaft 10 is rotationally driven. In turn, when power is generated by being rotationally driven by the crankshaft 10, the power storage device 61 is charged with the generated power. When the vehicle decelerates, regenerative braking is performed by the ISG 110, and the kinetic energy of the vehicle can be recovered as electric energy.

  Power storage device 61 includes a battery and / or a capacitor. In this embodiment, the main power storage device 611 and the sub power storage device 612 are mounted on the vehicle. The main power storage device 611 is, for example, a well-known lead battery for vehicles. The sub power storage device 612 is, for example, a nickel metal hydride battery, a lithium ion battery, a capacitor, or the like. The sub power storage device 612 can recover and store regenerative power that cannot be necessarily recovered by the main power storage device 611. A switch (or relay) 613 capable of switching connection / disconnection is provided on an electric circuit connecting the sub power storage device 612 and the ISG 110 or the like. The switch 613 is disconnected (opened) at the time of cold start of the internal combustion engine 100 and immediately after the cold start, and is connected after the main power storage device 611 is fully charged or close to full charge. The

  The compressor 130 for compressing the refrigerant of the air conditioner mounted on the vehicle is also connected to one end side of the crankshaft 10 of the internal combustion engine 100 via the winding transmission mechanisms 102, 134, 133, similarly to the ISG 110. . Pulleys (or sprockets) 133 and 102 are fixed to the input shaft 132 and the crankshaft 10 of the compressor 130, respectively, and the belt (or chain) 134 wound around the pulleys 133 and 102 causes the crankshaft 10 The rotational driving force is transmitted to the input shaft 132. The belt 134 may transmit driving force to a lubricating oil pump (not shown), a cooling water pump (not shown), or the like, which is an auxiliary machine other than the compressor 130. A magnet clutch 131 that can be connected and disconnected is provided between the main body of the compressor 130 and the input shaft 132, and the clutch 131 is disconnected when the air conditioner is not operated.

  The transmission 120 that connects the internal combustion engine 100 and the axle 153 is installed on the other end side of the crankshaft 10.

  As is well known, various electric loads are mounted on the vehicle. Specific examples of electrical loads include air conditioner blowers, rear glass defoggers, audio equipment, car navigation systems, lighting (headlamps, taillights, stoplights (brakelights), foglights, turn signals (turns) Signal lamp)), a radiator fan for cooling the cooling water of the internal combustion engine, an electric power steering device, and the like. These electric loads are supplied with necessary electric power from the ISG 110 and / or the power storage device 61 serving as a generator.

  FIG. 3 shows an equivalent circuit of ISG110. When the ISG 110 is operated as a generator, a three-phase AC induced current is generated in the stator coil 115 which is a three-phase coil. The induced current is supplied to the power storage device 61 and the electric load after being converted into a direct current by a rectifier 113 using a diode.

  A controller 114 attached to the ISG 110 receives a control signal n for instructing a target value of an output voltage of the ISG 110, which is issued from an ECU (Electronic Control Unit) 0 that is a control device of the present embodiment. Then, in order to make the terminal voltage of the power storage device 61 (in other words, the power supply voltage supplied to the electrical system) follow the commanded target voltage, the exciting current applied to the rotor coil 116 by switching the semiconductor switching element 119 PWM (Pulse Width Modulation) control is performed to adjust the size of. The output voltage of the ISG 110, that is, the generated voltage induced in the stator coil 115, increases as the exciting current flowing through the rotor coil 116 increases.

  The ISG 110 that operates as a generator is a mechanical load when viewed from the internal combustion engine 100. When the output voltage of the ISG 110 exceeds the terminal voltage of the power storage device 61, the power storage device 61 is charged and power is supplied from the ISG 110 to the electric load. That is, the ISG 110 spends the energy of rotation of the crankshaft 10 to generate electrical energy. The amount of charge to the power storage device 61 and the amount of power supplied to the electrical load depend on the potential difference between the output voltage of the ISG 110 and the terminal voltage of the power storage device 61.

  Conversely, when the output voltage of ISG 110 is less than or close to the terminal voltage of power storage device 61, power storage device 61 is not charged, and no power is supplied from ISG 110 to the electrical load (power from power storage device 61 to the electrical load). May be supplied). In other words, the ISG 110 does not perform work that consumes the energy of rotation of the crankshaft 10, or the work is reduced. In short, when a high power generation voltage is commanded from the ECU 0 to the ISG 110, the mechanical load of the ISG 110 with respect to engine rotation increases, and when a low power generation voltage is commanded, the mechanical load of the ISG 110 with respect to engine rotation decreases.

  Incidentally, the controller 114 has a gradual excitation function that gradually increases the excitation current instead of increasing the excitation current stepwise when increasing the amount of power generated by the ISG 110 in accordance with an increase in the electrical load. This gradual excitation function avoids temporary concentration of the mechanical load on the internal combustion engine 100 and prevents a decrease in engine rotation in an idle operation or low load operation region.

  In addition, the controller 114 receives a control signal n that is issued from the ECU 0 and commands an upper limit value of the excitation current, detects the magnitude of the excitation current flowing through the rotor coil 116 via the sensor 117, and commands the excitation current. Regulated below the specified upper limit. The upper limit of the excitation current is intended to prevent the mechanical rotation on the internal combustion engine 100 from becoming excessive and the engine rotation from becoming unstable. Therefore, for example, when the refrigerant compression compressor 130 is operated and when it is not operated, the upper limit value of the excitation current is lower in the former case.

  Clipping to the upper limit value of the excitation current has priority over following the target voltage value of the generated voltage of the ISG 110. In other words, even if the terminal voltage of the power storage device 61 is still less than the target voltage commanded from the ECU 0, the controller 114, when the excitation current flowing through the rotor coil 116 has already reached the upper limit commanded from the ECU 0, The excitation current is not increased further.

  On the other hand, when the ISG 110 is operated as an electric motor for driving the crankshaft 10, a three-phase alternating current is passed through the inverter 118 using a semiconductor switching element to the stator coil 115 while energizing the rotor coil 116 with a required excitation current. Is applied to generate a rotating magnetic field around the rotor. The high side switch and the low side switch of each phase of the inverter 118 are fired / extinguished by the controller 114. At this time, the controller 114 receives a control signal n issued from the ECU 0 and instructing the output level of the ISG 110 serving as an electric motor. Then, in order to make the output of the ISG 110 follow the commanded output level, PWM control for adjusting the magnitude of the excitation current applied to the rotor coil 116 and / or the magnitude of the three-phase current applied to the stator coil 115. To implement. The output of the ISG 110 that applies a rotational driving force to the crankshaft 10 of the internal combustion engine 100 increases as the excitation current flowing through the rotor coil 116 increases, and increases as the three-phase current flowing through the stator coil 115 increases.

  FIG. 4 shows an example of a transmission 120 of a drive system provided in the vehicle. The transmission 120 includes a torque converter 7 and automatic transmissions 8 and 9. In particular, in the present embodiment, a forward / reverse switching device 8 using a planetary gear mechanism and a belt type CVT 9 which is a type of continuously variable transmission are adopted as components of the automatic transmissions 8 and 9.

  The rotational driving force output from the internal combustion engine 100 and / or the ISG 110 as an electric motor is input from the crankshaft 10 of the internal combustion engine 100 to the pump impeller 71 on the input side of the torque converter 7 and transmitted to the turbine runner 72 on the output side. The rotation of the turbine runner 72 is transmitted to the drive shaft 94 of the CVT 9 via the forward / reverse switching device 8 and rotates the driven shaft 95 through a shift in the CVT 9. The rotation of the driven shaft 95 is transmitted to the output gear 151. The output gear 151 meshes with the ring gear 152 of the differential device, and rotates the axle 153 and the drive wheels (not shown) via the differential device.

  The torque converter 7 includes a lockup mechanism. The lock-up mechanism is known in this field, and a lock-up clutch 73 that fastens the input side and the output side of the torque converter 7 so as not to rotate relative to each other, and an operation for switching the connection of the lock-up clutch 73. A lock-up solenoid valve (not shown) for controlling the hydraulic pressure (hydraulic pressure) is used as an element. The lockup solenoid valve is a flow rate control valve that receives a control signal t and changes its opening degree.

  In a vehicle equipped with CVT 9, when the vehicle speed is a predetermined value (for example, 10 km / h) or more, the torque converter 7 is almost always locked up. When the vehicle speed is equal to or lower than the predetermined value, the lockup of the torque converter 7 is released. During lockup, the lockup clutch 73 is pressed against the torque converter cover 74 and rotates together with the torque converter cover 74. At the time of lock-up, the rotational driving force input to the input side (drive plate) of the torque converter 7 passes from the torque converter cover 74 via the lock-up clutch 73 to the output side of the torque converter 7 and thus the forward / reverse switching device 8. Communicated directly to. At the time of lockup, the speed ratio, which is the ratio of the output side rotational speed of the torque converter 7 to the input side rotational speed, is 1.

  In turn, the lock-up clutch 73 is separated from the torque converter cover 74 at the time of non-lock-up. At the time of non-lock-up, the rotational driving force input to the input side of the torque converter 7 is transmitted from the torque converter cover 74 to the pump impeller 71 and the turbine 72 and is transmitted to the forward / reverse switching device 8. At the time of non-lock-up, the speed ratio of the torque converter 7 becomes smaller or larger than 1 depending on the driving state.

  In the forward / reverse switching device 8, the sun gear 81 communicates with the turbine runner 72, and the ring gear 82 communicates with the drive shaft 94. Between the planetary carrier 83 that supports the planetary gear 831 and the transmission case, a forward brake 84 that is a hydraulic clutch that can be connected and disconnected is interposed. Further, a reverse clutch 85, which is a hydraulic clutch capable of switching connection / disconnection, is also interposed between the planetary carrier 83 and the sun gear 81 (or the output side of the torque converter 7).

  In the D range of the traveling range, the forward brake 84 is engaged and the reverse clutch 85 is disconnected. As a result, the rotation of the output shaft of the torque converter 7 is reversed and decelerated and transmitted to the drive shaft 94 for forward travel. In turn, in the R range, the reverse clutch 85 is engaged and the forward brake 84 is disconnected. As a result, the sun gear 81 and the planetary carrier 83 rotate integrally, and the output shaft of the torque converter 7 and the drive shaft 94 are directly connected to perform reverse travel. A solenoid valve (not shown) that controls the hydraulic pressure for driving the forward brake 84 or the reverse clutch 85 to connect / disconnect is a flow rate control valve that receives a control signal u and changes its opening.

  In the N range of the non-traveling range, both the forward brake 84 and the reverse clutch 85 are disconnected. In the P range, the axle 153 is mechanically locked so as not to move.

  The CVT 9 includes a driving pulley 91 and a driven pulley 92, and a belt 93 wound around the pulleys 91 and 92 as elements. The drive pulley 91 is disposed behind the movable sheave 912, a fixed sheave 911 fixed to the drive shaft 94, a movable sheave 912 supported on the drive shaft 91 via a roller spline so as to be displaceable in the axial direction. A hydraulic servo 913 is provided, and the gear ratio can be changed steplessly by operating the hydraulic servo 913 and displacing the movable sheave 912. The driven pulley 92 is disposed on the back of the movable sheave 922, a fixed sheave 921 fixed to the driven shaft 95, a movable sheave 922 supported on the driven shaft 95 via a roller spline so as to be displaceable in the axial direction. A hydraulic servo 923 is provided, and a belt thrust necessary for torque transmission is applied by operating the hydraulic servo 923 and displacing the movable sheave 922.

  A hydraulic pump (hydraulic fluid) supplied to the forward brake 84 or the reverse clutch 85 to operate the travel range, and a hydraulic pump (discharge fluid) supplied to the hydraulic servos 913 and 923 to operate the gear ratio. (Not shown) is a known mechanical type (non-electric type) that operates by receiving torque transmitted from the crankshaft of the internal combustion engine. This hydraulic fluid is common to the fluid used for the torque converter 7.

  The ECU 0 is a microcomputer system having a processor, a memory, an input interface, an output interface, and the like. The input interface includes a vehicle speed signal a output from a vehicle speed sensor that detects the actual vehicle speed of the vehicle, a crank angle signal b output from an engine rotation sensor that detects the rotation angle of the crankshaft 10 and the engine speed, and an accelerator pedal. , An accelerator opening signal c output from a sensor that detects the depression amount of the engine or the opening of the throttle valve 32 as an accelerator opening (so-called required load), intake air temperature and intake air in the intake passage 3 (especially the surge tank 33). Intake air temperature / intake pressure signal d output from a sensor for detecting atmospheric pressure, acceleration sensor for detecting vehicle acceleration (or an inclination angle sensor for detecting a gradient of a road surface where the vehicle is located) ( (Or inclination angle) signal e, cooling water temperature signal f output from a sensor for detecting the cooling water temperature of the internal combustion engine, intake camshaft A cam angle signal g output from the cam angle sensor at a plurality of cam angles, a voltage / current signal output from a sensor that detects the terminal voltage and / or terminal current (particularly, battery voltage or battery current) of the power storage device 61. h, a status signal s or the like provided from the controller 114 of the ISG 110 is input. The status signal s includes various information related to the ISG 110, such as the rotation speed and temperature, the magnitude of the excitation current flowing through the rotor coil 116, the current operation mode (that is, whether the power generation is being performed, the internal combustion engine 100 is being cranked, Information on whether the internal combustion engine 100 is motor-assisted or in a no-load state in which neither the generator nor the motor works.

  From the output interface of the ECU 0, an ignition signal i for the igniter of the spark plug 12, a fuel injection signal j for the injector 11, an opening operation signal k for the throttle valve 32, and an opening operation for the EGR valve 23. Signal l, control signal n for controlling the controller 114 of the ISG 110, clutch engagement signal o for the switch 62 on the electric circuit for energizing the magnet clutch 131, and connection / disconnection switching of the lockup clutch 73 An opening degree control signal t is output to the lockup solenoid valve, an opening degree control signal u is output to the solenoid valve for switching connection / disconnection of the forward brake 84 or the reverse clutch 85, a transmission ratio control signal v is output to the CVT 9 and the like. . The control signal n is a signal for instructing the operation mode of the ISG 110 and commanding the target value of the generated voltage output from the ISG 110 when operating as a generator, the output level of the ISG 110 when operating as an electric motor, and the like.

  The processor of the ECU 0 interprets and executes a program stored in advance in the memory, calculates operation parameters, and controls the operation of the internal combustion engine 100. The ECU 0 obtains various information a, b, c, d, e, f, g, h, and s necessary for operation control of the internal combustion engine 100 via the input interface, and requests the required throttle valve 32 opening degree and request. Fuel injection amount, fuel injection timing (including the number of times of fuel injection for one combustion), fuel injection pressure, ignition timing, whether or not to lock up the torque converter 7, the gear ratio of the CVT 9, the air conditioner Various operation parameters such as compressor ON / OFF, ISG 110 power generation amount or output are determined. The ECU 0 applies various control signals i, j, k, l, n, o, t, u, v corresponding to the operation parameters via the output interface.

  FIG. 5 shows a shift diagram when the ECU 0 controls the CVT 9. The shift diagram represents the target input rotation speed (rotation speed of the turbine 72) corresponding to the vehicle speed and the accelerator opening, and defines the transmission ratio of the CVT 9 corresponding to the vehicle speed and the accelerator opening. In FIG. 5, the shift line when the accelerator opening is 100% is drawn with a thick broken line, the shift line when it is 50% is drawn with a thick solid line, and the shift line when 0% is drawn with a thick chain line. . The gear ratio takes a value between the low gear side limit L and the high gear side limit H that the CVT 9 can implement in hardware.

  In addition, the ECU 0 inputs the control signal r to the starter motor 140 when the internal combustion engine 100 is started, particularly during cold start, and engages the pinion gear 141 with the ring gear 103 to crank the internal combustion engine 100.

  The ECU 0 performs a fuel cut that temporarily stops the fuel supply to the cylinder 1 when the predetermined fuel cut condition is satisfied and when the predetermined fuel cut condition is satisfied. ECU0, at least when the accelerator opening is 0 or below a threshold value close to 0, the engine speed is equal to or higher than the fuel cut permission speed, and a predetermined time has elapsed since the end of the last fuel cut, It is determined that the fuel cut condition is satisfied. Then, fuel injection from the injector 11 is interrupted.

  When the predetermined fuel cut end condition is satisfied after the fuel cut condition is satisfied, the fuel cut is ended, and the fuel supply to the cylinder 1 is resumed. The ECU 0 determines that the fuel cut end condition is satisfied, for example, when the accelerator opening exceeds the threshold value, the engine speed decreases to the fuel cut return speed, and the injector 11 that has been interrupted. Restart the fuel injection from.

  In addition, the ECU 0 of the present embodiment causes the ISG 110 to operate as an electric motor when the accelerator opening is 0 or less than a threshold value close to 0 and the vehicle travels on the coast, and causes the crankshaft 10 and the axle 153 of the internal combustion engine 100 to operate. A coast assist that gives a rotational driving force is executed. By this coast assist, the deceleration of the vehicle during coasting is reduced, and the decrease in the engine speed is delayed and the fuel cut period is extended.

However, it is not efficient to always perform a certain coast assist regardless of the current situation of the vehicle. More specifically, the degree of reduction in vehicle deceleration by increasing the output of the ISG 110 as an electric motor decreases as the vehicle speed at that time increases. When the reduction amount of the deceleration of the vehicle when the output of the ISG 110 is increased by ΔP is set to Δα, the weight of the vehicle is set to M, and the vehicle speed is set to V,
Δα ≒ ΔP / (MV)
This relationship is established. In other words, the effect of the coast assist is inversely proportional to the vehicle speed. Moreover, when the vehicle speed is high, the engine speed is often high, and there is still a grace period until the engine speed reaches the fuel cut return speed. Therefore, even if coast assist is executed when the vehicle speed is high, it is considered that the effect of improving the fuel consumption and drivability is poor compared to the power consumption by the operation of the ISG 110.

  In addition, when the vehicle is traveling on an uphill road, the deceleration of the vehicle is remarkably large in the first place, so it is difficult to extend the fuel cut period even if coast assist is executed, and the power consumption is merely wasted. . In addition, there are few opportunities for recovering electrical energy by regenerative power generation on the uphill road, and it is expected that the fuel efficiency will be improved if coast assistance is not executed.

  Conversely, when the vehicle is traveling on a downhill road, the rotation of the axle 153 and the crankshaft 10 is unlikely to decline. Accordingly, the fuel cut period is naturally extended without executing the coast assist. Not only that, when coast assist is executed on a downhill road, there is a concern that it gives the passenger a jumping out feeling that the vehicle accelerates, leading to deterioration of drivability.

  Furthermore, the transmission ratio of the CVT 9 is also related to the deceleration of the vehicle. When the gear ratio of the CVT 9 is still close to the high gear, that is, when the gear ratio is relatively small, the engine braking action that attempts to brake the rotation of the axle 153 and the crankshaft 10 becomes relatively small. There is no need to execute.

  Therefore, the ECU 0 of the present embodiment determines whether or not to execute coast assist, and the magnitude of the output of the ISG 110 when executing coast assist, the speed of the vehicle during coasting, the deceleration of the vehicle, and the shift of the CVT 9 Adjust according to the ratio.

FIG. 7 shows a procedure example of processing executed by the ECU 0 during coasting. First, the ECU 0 sets a base assist level corresponding to the current vehicle speed (step S1). The base assist level is a basic value of the output of the ISG 110 as an electric motor during coasting. FIG. 6 illustrates the relationship between the vehicle speed during coasting and the base assist level. In a high speed range where the vehicle speed is higher than the predetermined value V ₁ , that is, a time before time t ₁ in FIG. That is, the ISG 110 is not operated as an electric motor, and the rotational driving force is not output from the ISG 110.

In the low speed range where the vehicle speed is lower than the predetermined value V ₂ lower than the predetermined value V ₁ , that is, in the period after the time point t ₂ in FIG. 6, the base assist level is set to a predetermined value, and the ISG 110 that is the motor is turned on. A rotational driving force with a predetermined output is generated, and the driving force is applied to the crankshaft 10 of the internal combustion engine 100.

In the region where the vehicle speed is in the range from V ₂ to V ₁ , that is, in the period from time t ₁ to time t ₂ in FIG. 6, the base assist level is a value lower than a predetermined value corresponding to the low vehicle speed range. By setting to, a rotational driving force having a smaller output than that in the low speed range is applied from the ISG 110 to the crankshaft 10 of the internal combustion engine 100. The output of the ISG 110 in the region increases as the vehicle speed decreases.

Generally speaking, during coasting, coast assistance by the ISG 110 is executed when the vehicle speed is less than the predetermined value V ₁ , and coast assistance is not executed when the vehicle speed is the predetermined value V ₁ or more. In executing the coast assist, the output of the ISG 110 in a situation where the vehicle speed is low is increased as compared with the output of the ISG 110 in a situation where the vehicle speed is higher.

  In the memory of the ECU 0, map data or a function expression that defines the relationship between the vehicle speed and the base assist level is stored in advance. In step S1, the ECU 0 searches the map using the current vehicle speed as a key, or substitutes the current vehicle speed into the function formula to know the base assist level to be set.

  Next, the ECU 0 sets the assist level limit according to the deceleration of the current vehicle or the gradient of the road surface on which the current vehicle is located (step S2). For example, when the limitation level of the assist level is enumerated, the upper limit value of the assist level that is the output level of the ISG 110 is set to 0 when the deceleration of the vehicle or the gradient of the road surface is greater than a predetermined value. . In other words, coast assistance is not executed regardless of the base assist level.

  In addition, when the vehicle deceleration is less than a predetermined value or a negative value (acceleration is positive, that is, the vehicle is accelerating) or the road surface has a large downward slope, It is also possible to set the upper limit value of the assist level to 0 so that the coast assist is not executed.

  In an area where the vehicle deceleration or the road slope is relatively large (greater than a predetermined value), the upper limit value of the assist level may be set lower as the vehicle deceleration or the road slope is larger. In other words, when you think that you are approaching an uphill road or a rough road with a large running resistance, you can set the upper limit of the assist level in the situation where the vehicle deceleration, road uphill slope or running resistance is high, the vehicle deceleration, road surface Reduced compared to the upper limit in situations where the ascending slope or running resistance is smaller.

  On the other hand, in an area where the deceleration of the vehicle is remarkably small (smaller than a predetermined value), it is conceivable that the upper limit value of the assist level is set lower as the deceleration of the vehicle becomes smaller. In other words, when it is assumed that the vehicle is traveling on a downhill road with a low running resistance, the upper limit value of the assist level in a situation where the vehicle deceleration or running resistance is low is set as the upper limit value in the situation where the vehicle deceleration or running resistance is higher. Reduce compared to the value.

  In the memory of the ECU 0, map data or a function formula that prescribes the relationship between the deceleration of the vehicle or the road surface gradient and the upper limit value of the assist level is stored. In step S2, the ECU 0 searches the map using the current deceleration or gradient as a key, or substitutes the current deceleration or gradient into the function formula to know the upper limit value of the assist level to be set. .

  Further, the ECU 0 sets the assist level limit according to the current gear ratio of the CVT 9 (step S3). For example, when the gear ratio of the CVT 9 is a high gear with a predetermined value or less, the upper limit value of the assist level that is the output level of the ISG 110 is set to 0, and coast assistance is not executed regardless of the base assist level. And

  Further, the upper limit value of the assist level may be set lower as the gear ratio of the CVT 9 becomes smaller, that is, as the gear is higher. That is, in a situation where the gear ratio of CVT 9 is small, the engine braking action in coasting works greatly, so the upper limit value of the assist level is reduced compared to the upper limit value in a situation where the gear ratio of CVT 9 is larger.

  In the memory of the ECU 0, map data or a function expression that defines the relationship between the transmission ratio of the CVT 9 and the upper limit value of the assist level is stored in advance. In step S3, the ECU 0 searches the map using the current gear ratio as a key, or substitutes the current gear ratio into the function formula to know the upper limit value of the assist level to be set.

  Thus, the ECU 0 selects the smallest one from the base assist level set in step S1, the upper limit value of the assist level set in step S2, and the upper limit value of the assist level set in step S3. Then, the final assist level is determined (step S4), and the output of the ISG 110 as the electric motor is controlled to the assist level or smaller.

  In the present embodiment, in the control device 0 that controls a vehicle including the electric motor 110 that can apply a rotational driving force to the output shaft 10 or the axle 153 of the internal combustion engine 100, the internal combustion engine 10 Whether to perform coast assist for applying rotational driving force to the output shaft 10 or the axle 153 of the engine 100, and whether to perform coast assist for applying rotational driving force from the motor 110 at that time. Is determined depending on the speed of the vehicle, the deceleration of the vehicle or the gradient of the road surface, and the gear ratio of the transmission 9 interposed between the output shaft 10 and the axle 153 of the internal combustion engine 100.

  According to this embodiment, the energy efficiency at the time of coast driving | running | working of a vehicle can be improved further, and the improvement of drivability can be aimed at. Adjusting the output of the ISG 110, which is an electric motor according to the vehicle speed, is equivalent to adjusting the output of the ISG 110 according to the coast assist effect, that is, the vehicle deceleration reduction effect. In a high vehicle speed range where the effect of coast assist is small, the power consumption is suppressed by reducing the output of the ISG 110 or not operating the ISG 110. Similarly, the output of the ISG 110 is reduced or the ISG 110 is not operated even during an uphill run where the effect of the coast assist cannot be expected, during a downhill run where the need for the coast assist is poor, and in a high geared situation. As a result, the amount of fuel consumed for power generation can be reduced, which can contribute to lower fuel consumption.

  The present invention is not limited to the embodiment described in detail above. In the above embodiment, whether or not to perform coast assist during coasting, and the magnitude of the output of the motor for coast assist to the vehicle speed, deceleration or road gradient, and the transmission gear ratio. Was determined based on. However, whether or not coast assist is executed during coast driving and / or the output of the motor for coast assist may be determined based only on the vehicle speed. It may be determined based only on the gradient, or may be determined based only on the transmission gear ratio. In that case, the base assist level set in accordance with the contents of step S1 described above, the upper limit value of the assist level set in accordance with the contents of step S2, or the upper limit value of the assist level set in accordance with the contents of step S3 is the same as the motor. Assist level that regulates output.

  Alternatively, whether or not coast assist is executed during coasting and / or the output of the motor for coast assist is determined by the vehicle speed, vehicle deceleration or road gradient, and transmission gear ratio. You may decide based on two of the elements. In that case, two of the base assist level set according to the content of step S1 described above, the upper limit value of the assist level set according to the content of step S2, and the upper limit value of the assist level set according to the content of step S3. Select and use, the smaller of the two is the final assist level.

  The electric motor that accompanies the internal combustion engine is not limited as long as it can rotate the output shaft or the axle of the internal combustion engine, and does not necessarily have a function as a generator.

  Moreover, the aspect of the transmission employed in the drive system of the vehicle is not limited to the belt type CVT.

  In addition, the specific configuration of each unit, the processing procedure, and the like can be variously modified without departing from the spirit of the present invention.

  INDUSTRIAL APPLICABILITY The present invention can be applied to control during coasting of a vehicle accompanied by an electric motor capable of rotating the output shaft or axle of an internal combustion engine.

0 ... Control unit (ECU)
9 ... Transmission (CVT)
10 ... Output shaft (crankshaft) of internal combustion engine
DESCRIPTION OF SYMBOLS 100 ... Internal combustion engine 110 ... Generator / motor (ISG)
153 ... Axle

Claims (3)

Controlling a vehicle equipped with an electric motor capable of applying a rotational driving force to an output shaft or axle of an internal combustion engine,
When the vehicle travels on the coast, a rotational driving force is applied from the electric motor to the output shaft or axle of the internal combustion engine,
The speed of the motor, whether or not to apply rotational driving force from the motor, the speed of the vehicle, the deceleration of the vehicle or the gradient of the road surface, the speed change interposed between the output shaft and the axle of the internal combustion engine A vehicle control device that changes in accordance with at least one of the gear ratios of the machine. When the vehicle travels on the coast, the output shaft of the internal combustion engine or the magnitude of the output of the electric motor that applies the rotational driving force to the axle, or whether the rotational driving force is applied from the electric motor, the vehicle speed, the vehicle deceleration or The vehicle control device according to claim 1, wherein the vehicle control device changes according to at least two of a road surface gradient and a transmission gear ratio. When the vehicle travels on the coast, the output shaft of the internal combustion engine or the magnitude of the output of the electric motor that applies the rotational driving force to the axle, or whether the rotational driving force is applied from the electric motor, the vehicle speed, the vehicle deceleration or The vehicle control device according to claim 1, wherein the vehicle control device changes in accordance with a road surface gradient and a transmission gear ratio.

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