JP2012219795A - Vehicle and control method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle allowing a driver to select either normal mode or eco-mode to prevent wheels from being locked on a step difference or a hill.SOLUTION: The vehicle includes normal mode and eco-mode in which the vehicle drive power with respect to the same accelerator operation amount is lower than that of the normal mode. The vehicle includes an accelerator operation detecting unit for detecting an accelerator operation amount by the driver, and a drive force setting unit for setting a vehicle drive force based on the detected accelerator operation amount. The drive force setting unit sets a vehicle drive force so that during the eco-mode, the lower the vehicle speed becomes, the difference from a vehicle drive force set in the normal mode with respect to the same accelerator operation amount decreases.

Description

  The present invention relates to a vehicle and a control method thereof, and more specifically to a vehicle having a normal mode and a fuel efficiency priority mode in which a vehicle driving force with respect to the same accelerator operation amount is smaller than that of the normal mode, and a control method thereof.

  Conventionally, hybrid vehicles having a plurality of driving modes with different control methods have been proposed. For example, a vehicle having a power mode that emphasizes responsiveness of driving force to an accelerator operation and a vehicle that has a fuel efficiency priority mode (hereinafter referred to as an eco mode) that emphasizes improvement in fuel efficiency have been proposed. Among these, in the vehicle having the eco mode, when the eco mode is set, energy saving is realized by making the vehicle driving force for the same accelerator operation amount smaller than that in the normal mode corresponding to the normal travel.

Japanese Patent Laid-Open No. 9-4482

  In a vehicle having the eco mode as described above, in the eco mode, the vehicle driving force for a predetermined accelerator operation amount is smaller than the vehicle driving force set for the same accelerator operation amount in the normal mode. In situations where a reaction force in the direction opposite to the traveling direction is applied to the vehicle, such as on the road, the vehicle output torque cannot exceed this reaction force even if the driver depresses the accelerator pedal. There is a risk that a locked state may occur.

  Therefore, the present invention has been made to solve such a problem, and an object of the present invention is to suppress the occurrence of a locked state of wheels on a step or an uphill road in a vehicle having an eco mode.

  According to an aspect of the present invention, there is provided a vehicle having a first traveling mode and a second traveling mode in which the vehicle driving force for the same accelerator operation amount is smaller than that of the first traveling mode. An accelerator operation detection unit for detecting the accelerator operation amount and a driving force setting unit for setting the vehicle driving force based on the detected accelerator operation amount are provided. In the second traveling mode, the driving force setting unit decreases the vehicle driving force so that the difference between the same accelerator operation amount and the vehicle driving force set in the first traveling mode decreases as the vehicle speed decreases. Set.

  Preferably, the vehicle further includes a vehicle speed detection unit for detecting the vehicle speed. When the detected vehicle speed is lower than a predetermined threshold value in the second traveling mode, the driving force setting unit is equal to the vehicle driving force set in the first traveling mode with respect to the same accelerator operation amount. Set the vehicle driving force.

  Preferably, the vehicle is configured to travel forward by the vehicle driving force generated by the internal combustion engine and the electric motor, and to travel backward by generating the vehicle driving force only from the electric motor. When the detected vehicle speed is lower than a predetermined threshold in the second traveling mode, the driving force setting unit is configured to be equal to or greater than the vehicle driving force set in the first traveling mode with respect to the same accelerator operation amount. The vehicle driving force when the vehicle travels backward is set.

  Preferably, the driving force setting unit sets a predetermined threshold based on the vehicle speed when the wheel is in a locked state.

  According to another aspect of the present invention, there is provided a vehicle control method including a first travel mode and a second travel mode in which the vehicle driving force for the same accelerator operation amount is smaller than the first travel mode. And a step for detecting the accelerator operation amount of the driver, and a step for setting the vehicle driving force based on the detected accelerator operation amount. In the setting step, the vehicle driving force is set such that the difference from the vehicle driving force set in the first travel mode with respect to the same accelerator operation amount decreases as the vehicle speed decreases.

  According to the present invention, in a vehicle having an eco mode, even when the eco mode is selected as the travel mode, the vehicle driving force can be increased in a situation where there is a possibility that the wheel is locked. it can. Thereby, it can suppress that a locked state generate | occur | produces on a wheel at the time of eco mode.

1 is a schematic configuration diagram of a hybrid vehicle shown as a representative example of a vehicle according to an embodiment of the present invention. FIG. 2 is a schematic diagram for explaining details of a power train in the hybrid vehicle of FIG. 1. It is a block diagram which shows the control structure in ECU according to this Embodiment. It is a figure which shows an example of the map for throttle opening setting for control. It is a figure which shows an example of the map for request | requirement torque setting. It is a conceptual diagram which shows the area | region which can operate | move motor generator MG2 in the hybrid vehicle by this Embodiment. It is a figure which shows an example of the eco mode map set for every vehicle speed range. It is a flowchart which shows the setting operation | movement of the accelerator opening for control in ECU by this Embodiment. It is a figure which shows an example of the eco mode map for very low vehicle speed areas by this example of a change.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

(Vehicle configuration)
FIG. 1 is a schematic configuration diagram of a hybrid vehicle 5 shown as a representative example of a vehicle according to an embodiment of the present invention.

  Referring to FIG. 1, hybrid vehicle 5 includes an engine ENG, motor generators MG1 and MG2, a battery 10, a power conversion unit (PCU: Power Control Unit) 20, a power split mechanism PSD, a reduction gear RD, Front wheels 70L and 70R, rear wheels 80L and 80R, and an electronic control unit (ECU) 30 are provided. The control device according to the present embodiment is realized, for example, by a program executed by ECU 30. 1 illustrates the hybrid vehicle 5 using the front wheels 70L and 70R as drive wheels, the rear wheels 80L and 80R may be used as drive wheels instead of the front wheels 70L and 70R. Alternatively, in addition to the configuration shown in FIG. 1, a motor generator for driving the rear wheels 80L and 80R may be further provided to provide a 4WD configuration.

  The driving force generated by the engine ENG is divided into two paths by the power split mechanism PSD. One is a path for driving the front wheels 70L and 70R via the reduction gear RD. The other is a path for generating electric power by driving the motor generator MG1.

  Motor generator MG1 is typically constituted by a three-phase AC synchronous motor generator. Motor generator MG1 generates electricity as a generator by the driving force of engine ENG divided by power split mechanism PSD. Motor generator MG1 has not only a function as a generator but also a function as an actuator for controlling the rotational speed of engine ENG.

  The electric power generated by motor generator MG1 is selectively used according to the driving state of the vehicle and the state of charge (SOC) of battery 10. For example, during normal running or sudden acceleration, the electric power generated by motor generator MG1 is used as power for driving motor generator MG2 as a motor. On the other hand, when the SOC of battery 10 is lower than a predetermined value, the power generated by motor generator MG1 is converted from AC power to DC power by power conversion unit 20 and stored in battery 10.

  The motor generator MG1 is also used as a starter when starting the engine ENG. When starting engine ENG, motor generator MG1 is supplied with electric power from battery 10 and is driven as an electric motor. Then, motor generator MG1 cranks engine ENG and starts it.

  Motor generator MG2 is typically constituted by a three-phase AC synchronous motor generator. When motor generator MG2 is driven as an electric motor, it is driven by at least one of electric power stored in battery 10 and electric power generated by motor generator MG1. The driving force of motor generator MG2 is transmitted to front wheels 70L and 70R via reduction gear RD. Thus, motor generator MG2 assists engine ENG to travel the vehicle or causes the vehicle to travel only by the driving force of motor generator MG2.

  During regenerative braking of the vehicle, the motor generator MG2 is driven by the front wheels 70L and 70R via the reduction gear RD, and the motor generator MG2 is operated as a generator. Thus, motor generator MG2 acts as a regenerative brake that converts braking energy into electric energy. The electric power generated by motor generator MG2 is stored in battery 10 via power conversion unit 20.

  The battery 10 is constituted by a secondary battery such as nickel hydride or lithium ion, for example. In the embodiment of the present invention, the battery 10 is shown as a representative example of the power storage device. That is, another power storage device such as an electric double layer capacitor can be used in place of the battery 10. The battery 10 supplies a DC voltage to the power conversion unit 20 and is charged by the DC voltage from the power conversion unit 20.

  The power conversion unit 20 performs bidirectional power conversion between DC power supplied by the battery 10, AC power for driving and controlling the motor, and AC power generated by the generator.

  The hybrid vehicle 5 further includes a steering wheel 40, an accelerator position sensor 44 that detects an accelerator opening Acc corresponding to the amount of depression of the accelerator pedal by the driver, a brake pedal position sensor 46 that detects a brake pedal position BP, and a shift. And a shift position sensor 48 for detecting the position SP.

  Motor generators MG1 and MG2 are further provided with rotation angle sensors 51 and 52 for detecting the rotor rotation angle. Rotor rotation angle θ1 of motor generator MG1 detected by rotation angle sensor 51 and rotor rotation angle θ2 of motor generator MG2 detected by rotation angle sensor 52 are transmitted to ECU 30. The rotation angle sensors 51 and 52 estimate the rotor rotation angle θ1 from the current, voltage and the like of the motor generator MG1 in the ECU 30, and estimate the rotor rotation angle θ2 from the current, voltage and the like of the motor generator MG2. The arrangement may be omitted.

  The hybrid vehicle 5 further includes an eco switch 90. The eco switch 90 is a switch for the driver to select driving in the fuel efficiency priority mode (eco mode) that emphasizes fuel efficiency improvement. The eco switch 90 is electrically connected to the ECU 30. The ECU 30 receives an eco switch signal Esw indicating the on / off state of the eco switch 90. When the eco switch signal Esw is on, the ECU 30 determines that the eco mode is selected by the driver.

  ECU 30 is electrically connected to engine ENG, power conversion unit 20 and battery 10. Based on the detection signals from the various sensors and the eco switch signal Esw from the eco switch 90, the ECU 30 drives the engine ENG and the motor generators MG1 and MG2 so that the hybrid vehicle 5 enters a desired running state. The state and the charge state of the battery 10 are controlled in an integrated manner.

  FIG. 2 is a schematic diagram for explaining details of the power train in the hybrid vehicle 5 of FIG. 1.

  Referring to FIG. 2, the power train (hybrid system) of hybrid vehicle 5 includes motor generator MG2, reduction gear RD connected to output shaft 160 of motor generator MG2, engine ENG, motor generator MG1, A splitting mechanism PSD.

  In the example shown in FIG. 2, the power split mechanism PSD is constituted by a planetary gear mechanism, and a sun gear 151 coupled to a hollow sun gear shaft penetrating the crankshaft 150 through the center of the shaft, and rotates coaxially with the crankshaft 150. The ring gear 152 that is supported, the pinion gear 153 that is disposed between the sun gear 151 and the ring gear 152 and revolves around the outer periphery of the sun gear 151, and the rotation of each pinion gear 153 coupled to the end of the crankshaft 150. And a planetary carrier 154 that supports the shaft.

  In power split mechanism PSD, three axes of a sun gear shaft coupled to sun gear 151, a ring gear case 155 coupled to ring gear 152, and crankshaft 150 coupled to planetary carrier 154 serve as power input / output shafts. When the power input / output to / from any two of the three axes is determined, the power input / output to the remaining one axis is determined based on the power input / output to the other two axes.

  A counter drive gear 170 for extracting power is provided outside the ring gear case 155 and rotates integrally with the ring gear 152. Counter drive gear 170 is connected to power transmission reduction gear RG. The ring gear case 155 corresponds to the “output member” in the present invention. In this way, power split device PSD operates to output at least a part of the output from engine ENG to the output member with the input and output of electric power and power by motor generator MG1.

  Further, power is transmitted between the counter drive gear 170 and the power transmission reduction gear RG. The power transmission reduction gear RG drives a differential gear DEF coupled to the front wheels 70L and 70R that are drive wheels. On the downhill or the like, the rotation of the driving wheel is transmitted to the differential gear DEF, and the power transmission reduction gear RG is driven by the differential gear DEF.

  Motor generator MG1 includes a stator 131 that forms a rotating magnetic field, and a rotor 132 that is disposed inside stator 131 and has a plurality of permanent magnets embedded therein. Stator 131 includes a stator core 133 and a three-phase coil 134 wound around stator core 133. Rotor 132 is coupled to a sun gear shaft that rotates integrally with sun gear 151 of power split device PSD. The stator core 133 is formed by laminating thin electromagnetic steel plates, and is fixed to a case (not shown).

  Motor generator MG1 operates as an electric motor that rotationally drives rotor 132 by the interaction between the magnetic field generated by the permanent magnet embedded in rotor 132 and the magnetic field formed by three-phase coil 134. Motor generator MG1 also operates as a generator that generates electromotive force at both ends of three-phase coil 134 due to the interaction between the magnetic field generated by the permanent magnet and the rotation of rotor 132.

  Motor generator MG2 includes a stator 136 that forms a rotating magnetic field, and a rotor 137 that is disposed inside stator 136 and has a plurality of permanent magnets embedded therein. Stator 136 includes a stator core 138 and a three-phase coil 139 wound around stator core 138.

  The rotor 137 is coupled to a ring gear case 155 that rotates integrally with the ring gear 152 of the power split mechanism PSD via a reduction gear RD. Stator core 138 is formed, for example, by laminating thin magnetic steel sheets, and is fixed to a case (not shown).

  Motor generator MG2 also operates as a generator that generates an electromotive force at both ends of three-phase coil 139 by the interaction between the magnetic field generated by the permanent magnet and the rotation of rotor 137. Motor generator MG2 operates as an electric motor that rotates rotor 137 by the interaction between the magnetic field generated by the permanent magnet and the magnetic field formed by three-phase coil 139.

  The speed reducer RD performs speed reduction by a structure in which a planetary carrier 166 that is one of rotating elements of a planetary gear is fixed to a case. That is, reduction device RD meshes with sun gear 162 coupled to output shaft 160 of rotor 137, ring gear 168 that rotates integrally with ring gear 152, ring gear 168 and sun gear 162, and transmits the rotation of sun gear 162 to ring gear 168. Pinion gear 164. For example, by reducing the number of teeth of the ring gear 168 to more than twice the number of teeth of the sun gear 162, the reduction ratio can be increased more than twice.

  Thus, the rotational force of motor generator MG2 is transmitted to output member (ring gear case) 155 that rotates integrally with ring gears 152 and 168 via reduction gear RD. That is, motor generator MG2 is configured to apply power between output member 155 and the drive wheel. Note that the arrangement of the reduction gear RD may be omitted, that is, the output shaft 160 of the motor generator MG2 and the output member 155 may be connected without providing a reduction ratio.

  Power conversion unit 20 includes a converter 12 and inverters 14 and 22. Converter 12 converts DC voltage Vb from battery 10 and outputs DC voltage VH between power supply line PL and ground line GL. Converter 12 is configured to be capable of voltage conversion in both directions, and converts DC voltage VH between power supply line PL and ground line GL into charging voltage Vb of battery 10.

  Inverters 14 and 22 are constituted by general three-phase inverters, convert DC voltage VH between power supply line PL and ground line GL into an AC voltage, and output the AC voltage to motor generators MG2 and MG1, respectively. Inverters 14 and 22 convert the AC voltage generated by motor generators MG2 and MG1 into DC voltage VH and output the voltage between power supply line PL and ground line GL.

  The hybrid vehicle 5 configured as described above is configured to be able to travel by selecting a normal mode corresponding to normal traveling and an eco mode that prioritizes fuel consumption compared to the normal mode. The driver can select either the normal mode or the eco mode by operating the eco switch 90. As will be described later, the ECU 30 stores a table in which the selected travel mode and the required torque to be output to the output member 155 are associated with each other. The required torque stored in this table is set such that the driving force obtained for a predetermined accelerator opening Acc is smaller in the eco mode than in the normal mode. The ECU 30 calculates a required torque to be output to the output member 155 based on the accelerator opening Acc with reference to this table in each travel mode. Then, the operating state of engine ENG and the driving states of motor generators MG1, MG2 are controlled so that the required driving force corresponding to this required torque is output to output member 155.

(Control structure)
Next, a control structure for realizing the operation of hybrid vehicle 5 according to the present embodiment will be described with reference to FIG.

  FIG. 3 is a block diagram showing a control structure in ECU 30 according to the present embodiment. Each function block shown in FIG. 3 is typically realized by the ECU 30 executing a program stored in advance, but a part or all of the function may be implemented as dedicated hardware.

  Referring to FIG. 3, ECU 30 includes a travel mode selection unit 310, a charge / discharge control unit 320, a travel control unit 330, a distribution unit 340, an inverter control unit 350, and a converter control unit 360.

  When traveling mode selection unit 310 receives eco switch signal Esw from eco switch 90, it selects one of normal mode and eco mode based on eco switch signal Esw. The travel mode selection unit 310 generates a travel mode flag FM indicating which of the normal mode and the eco mode is selected. The travel mode flag FM is sent to the travel control unit 330.

  Charging / discharging control unit 320 sets charging power upper limit value Win and discharging power upper limit value Wout based on the SOC of battery 10. Although not shown, the SOC of the battery 10 is an estimated SOC value calculated based on battery data (current, voltage, and temperature of the battery 10) from a battery monitoring unit provided in the battery 10.

  The traveling control unit 330 calculates a vehicle driving force and a vehicle braking force necessary for the entire hybrid vehicle 5 according to the traveling mode, vehicle state, and driver operation of the hybrid vehicle 5. The vehicle state includes the vehicle speed V detected by the vehicle speed sensor 100. The driver operation includes an accelerator opening Acc, a brake pedal position BP, a shift position SP, and the like.

  Specifically, traveling control unit 330 sets control accelerator opening Acc * based on accelerator opening Acc. The travel control unit 330 stores in advance the relationship between the accelerator opening Acc and the control accelerator opening Acc * shown in FIG. 4 as a control accelerator opening setting map. Then, when the accelerator opening degree Acc is given from the accelerator position sensor 44, the traveling control unit 330 sets the corresponding control accelerator opening degree Acc * with reference to the stored map. FIG. 4 shows an example of a control accelerator opening setting map. In the figure, a “normal mode map” that is a control accelerator opening setting map in the normal mode and an “eco mode map” that is a control accelerator opening setting map in the eco mode are shown. .

  Referring to FIG. 4, in the normal mode map, control accelerator opening Acc * is determined to have linearity with respect to accelerator opening Acc in a range of 0 to 100%. On the other hand, in the eco mode map, in order to reduce the response of the torque output to the output member 155 to the accelerator operation, the eco mode map has nonlinearity that is smaller than the control accelerator opening Acc * in the normal mode. Thus, the accelerator opening Acc * for control is determined. When the hybrid vehicle 5 is set to the normal mode, the traveling control unit 330 refers to the normal mode map of FIG. 4 and controls the accelerator opening Acc * for control corresponding to the accelerator opening Acc from the accelerator position sensor 44. Set. On the other hand, when the hybrid vehicle 5 is set to the eco mode, the travel control unit 330 refers to the eco mode map of FIG. 4 and controls the accelerator opening for control corresponding to the accelerator opening Acc from the accelerator position sensor 44. Set Acc *.

  When the control accelerator opening Acc * is set in this way, the traveling control unit 330 requests to output to the output member 155 as the torque required for the vehicle based on the set control accelerator opening Acc * and the vehicle speed V. Set the torque Tr *. The traveling control unit 330 stores in advance a relationship among the control accelerator opening Acc *, the vehicle speed V, and the required torque Tr * as a required torque setting map. FIG. 5 shows an example of the required torque setting map. When the control accelerator opening Acc * and the vehicle speed V are given, the traveling control unit 330 refers to the required torque setting map and sets the corresponding required torque Tr *. Further, traveling control unit 330 sets required power Pe * required for engine ENG based on the set required torque Tr *.

  Travel control unit 330 determines an output request to motor generators MG1 and MG2 and an output request to engine ENG so as to realize required torque Tr * and required power Pe *. Hybrid vehicle 5 can travel only with the output of motor generator MG2 while engine ENG is stopped. Therefore, energy efficiency can be improved by determining each output request so as to operate the engine ENG while avoiding a region where the fuel efficiency is poor. Furthermore, the output request to motor generators MG1 and MG2 is set after limiting the charging and discharging of battery 10 within the power range (Win to Wout) in which battery 10 can be charged and discharged. That is, when the output power of battery 10 cannot be secured, the output from motor generator MG2 is limited.

  Distribution unit 340 calculates the torque and rotation speed of motor generators MG1 and MG2 in response to the output request to motor generators MG1 and MG2 set by travel control unit 330. Then, a control command for torque and rotation speed is output to inverter control unit 350, and at the same time, a control command value for voltage VH is output to converter control unit 360.

  On the other hand, the distribution unit 340 generates an engine control instruction indicating the required power Pe * determined by the travel control unit 330 and the engine target rotation speed. In accordance with this engine control instruction, fuel injection, ignition timing, valve timing, etc. of an engine ENG (not shown) are controlled.

  Inverter control unit 350, in response to a control command from distribution unit 340, a control signal for giving a drive instruction to convert a DC voltage, which is the output of converter 12, into an AC voltage for driving motor generator MG1, and a motor generator A control signal for generating a regeneration instruction for converting the AC voltage generated by MG1 into a DC voltage and returning it to the converter 12 side is generated. These motor generator MG1 control commands (MG1 control commands) are output to inverter 22. Similarly, inverter control unit 350 converts the AC signal generated by motor generator MG2 into a DC voltage and a control signal for instructing driving to convert DC voltage into AC voltage for driving motor generator MG2 to converter 12. And a control signal for instructing regeneration to be returned to the side. These motor generator MG2 control commands (MG2 control commands) are output to inverter 14.

  Converter control unit 360 provides a control signal for instructing boosting to converter 12, a control signal for instructing step-down instruction, and a shutdown signal for instructing prohibition of operation so that DC voltage VH is controlled in accordance with a control command from distribution unit 340. Is generated. The charge / discharge power of the battery 10 is controlled by the voltage conversion of the converter 12 according to these control signals.

  Next, the operation of the hybrid vehicle 5 according to the present embodiment, particularly the operation when the eco mode is set by the eco switch 90 will be described.

  As described with reference to FIG. 4, in the eco mode, the control accelerator opening Acc * is set to a value smaller than the control accelerator opening Acc * in the normal mode, so that the required torque Tr * with respect to the accelerator opening Acc is set. Is smaller than the required torque Tr * set for the same accelerator opening Acc in the normal mode. Therefore, in a scene where a reaction force opposite to the traveling direction acts on the hybrid vehicle 5 such as a step or an uphill road, the output torque of the hybrid vehicle 5 is also increased when the driver depresses the accelerator pedal. The force cannot be exceeded and the wheel may be locked.

  In particular, in the hybrid vehicle 5, when “D (drive) range” is selected as the shift range in accordance with the shift position SP, the engine is advanced so that the vehicle moves forward with a larger driving force as the accelerator opening degree Acc increases. Control is performed so that the vehicle moves forward as at least a drive source of ENG and motor generator MG2. On the other hand, when “R (reverse) range” is selected as the shift range according to the shift position SP, the engine ENG is operated so that the vehicle moves backward with a larger driving force as the accelerator opening Acc increases. The vehicle is stopped and controlled so that the vehicle moves backward using only motor generator MG2 as a drive source. For this reason, when the R range is selected as the shift range, the driving force of the vehicle is smaller than when the D range is selected as the shift range. There is a risk of a locked state.

  In a vehicle using only an electric motor as a drive source, such as an electric vehicle or a fuel cell vehicle, there is a concern that such a problem may occur not only during reverse travel but also during forward travel.

  In order to solve the above problems, in the vehicle according to the present embodiment, in the eco mode, the lower the vehicle speed, the difference between the vehicle driving force set in the normal mode for the same accelerator operation amount. The vehicle driving force is set so that becomes smaller. Specifically, the eco-mode map is changed according to the vehicle speed V so that the relationship between the accelerator opening Acc and the control accelerator opening Acc * approaches linear as the vehicle speed V decreases.

  FIG. 6 is a conceptual diagram showing an operable region of motor generator MG2 in hybrid vehicle 5 according to the present embodiment. Referring to FIG. 6, the operable region of motor generator MG2 is indicated by a combination of vehicle speed V and torque Tr. The limit of the operable region is determined by the DC voltage VH between the power supply line PL and the ground line GL, which is the inverter input voltage.

  In the present embodiment, the operable region shown in FIG. 6 is divided into a plurality of regions according to the vehicle speed V. In the figure, the vehicle is divided into three regions: an extremely low vehicle speed region (region I in the drawing), a low vehicle speed region (region II in the drawing), and a medium and high vehicle speed region (region III in the drawing). Note that the extremely low vehicle speed range (0 ≦ V ≦ V1) assumes a situation in which the wheel is locked. V1 is set in consideration of, for example, a lock region (very low rotation speed region) of the rotation speed of motor generator MG2. Then, for each vehicle speed range, an eco mode map that is a control accelerator opening setting map in the eco mode is set.

  FIG. 7 shows an example of an eco mode map set for each vehicle speed range. FIG. 7A shows an example of an eco mode map for an extremely low vehicle speed range. FIG. 7B shows an example of an eco mode map for a low vehicle speed range. FIG. 7C shows an example of an eco-mode map for medium and high vehicle speed ranges. In each of FIGS. 7A to 7C, the normal mode map shown in FIG. 4 is also shown.

  With reference to FIG. 7A, in the eco-mode map for the extremely low vehicle speed range, the control accelerator opening Acc * is determined to have linearity with respect to the accelerator opening Acc in the range of 0 to 100%. ing. Therefore, the control accelerator opening Acc * with respect to the accelerator opening Acc has the same value as the control accelerator opening Acc * set by the normal mode map.

  On the other hand, referring to FIG. 7C, the eco-mode map for medium and high vehicle speed ranges corresponds to the eco-mode map shown in FIG. 4, and the accelerator opening for control with respect to the same accelerator opening Acc. Acc * is determined to be smaller than the control accelerator opening Acc * set by the normal mode map.

  The low vehicle speed range eco-mode map shown in FIG. 7B is located between the extremely low vehicle speed range eco-mode map and the medium-high vehicle speed range eco-mode map. In this low vehicle speed range eco-mode map, the control accelerator opening Acc * for the same accelerator opening Acc is smaller than the control accelerator opening Acc * set by the extremely low vehicle speed eco-mode map, and It is determined to be a value greater than the control accelerator opening Acc * set by the medium and high vehicle speed range eco-mode map.

  With this configuration, in the eco mode, the control accelerator opening Acc * with respect to the predetermined accelerator opening Acc increases as the vehicle speed V decreases, and the control accelerator opening set by the normal mode map is opened. The difference from the degree Acc * is set to be small. Then, based on the set accelerator opening Acc * for control and the vehicle speed V, the required torque Tr * is calculated by the required torque setting map shown in FIG. It will be set so that it may become a large value. Thereby, the vehicle driving force can be increased as the vehicle speed is lower. Therefore, it can suppress that a locked state generate | occur | produces on a wheel in a level | step difference or an uphill road.

  In the present embodiment, a plurality of eco mode maps having different control accelerator opening Acc * for the same accelerator opening Acc are determined in advance corresponding to a plurality of vehicle speed ranges, thereby reducing the vehicle speed. Accordingly, the vehicle driving force can be gradually increased. Thereby, it is possible to suppress a sudden increase in the vehicle driving force with respect to the accelerator operation amount immediately after the vehicle speed enters the range of the extremely low vehicle speed range. In the present embodiment, the eco-mode map is determined in advance for each vehicle speed range by dividing the vehicle into three vehicle speed ranges, the extremely low vehicle speed range, the low vehicle speed range, and the medium-high vehicle speed range. The number of mode maps may be four or more.

  FIG. 8 is a flowchart showing the setting operation of the control accelerator opening Acc * in the ECU 30. The processing of this flowchart is executed every predetermined time or every time a predetermined condition is satisfied when the hybrid vehicle 5 is in a travelable state.

  Referring to FIG. 8, first, ECU 30 functioning as travel control unit 330 travels such as travel mode flag FM indicating the current travel mode, accelerator opening Acc from accelerator position sensor 44, and vehicle speed V from vehicle speed sensor 100. Data necessary for control is received (step S01).

  Next, the traveling control unit 330 determines whether or not the current traveling mode is the eco mode based on the traveling mode flag FM (step S02). If the current travel mode is not the eco mode, that is, if the current travel mode is the normal mode (NO determination in step S02), the travel control unit 330 is shown in FIG. 4 as a control accelerator opening setting map. Select the normal mode map. The travel control unit 330 refers to the normal mode map and sets the control accelerator opening Acc * based on the accelerator opening Acc (step S09).

  On the other hand, when the current travel mode is the eco mode (when YES is determined in step S02), the travel control unit 330 causes the vehicle speed V to be within the extremely low vehicle speed range (0 ≦ V ≦ V1). It is determined whether or not there is (step S03). When the vehicle speed V is within the extremely low vehicle speed range (when YES is determined in step S03), the traveling control unit 330 uses the extremely low vehicle speed shown in FIG. 7A as the control accelerator opening setting map. Select eco-mode map for area. The travel control unit 330 refers to the extremely low vehicle speed range eco-mode map and sets the control accelerator opening Acc * based on the accelerator opening Acc (step S09).

  On the other hand, when the vehicle speed V is not within the extremely low vehicle speed range (when NO is determined in step S03), the traveling control unit 330 determines that the vehicle speed V is within the low vehicle speed range (V1 <V ≦ V2). It is determined whether or not it enters (step S05). When the vehicle speed V is within the range of the low vehicle speed range (when YES is determined in step S05), the travel control unit 330 is used for the low vehicle speed range of FIG. Select the eco-mode map. The traveling control unit 330 sets the control accelerator opening Acc * based on the accelerator opening Acc with reference to the low vehicle speed range eco-mode map (step S09).

  On the other hand, when the vehicle speed V does not fall within the low vehicle speed range (when NO is determined in step S05), that is, when the vehicle speed V falls within the middle high vehicle speed range, The eco-mode map for medium and high vehicle speed ranges in FIG. 7C is selected as the map for setting the accelerator opening for control. The travel control unit 330 sets the control accelerator opening Acc * based on the accelerator opening Acc with reference to the eco-mode map for medium and high vehicle speed ranges (step S09).

  As described above, according to the embodiment of the present invention, in the eco mode, the vehicle driving force can be made closer to the vehicle driving force set in the normal mode with respect to the same accelerator operation amount as the vehicle speed decreases. . As a result, it is possible to generate a driving force necessary to overcome a step or the like, and thus it is possible to prevent the wheels from being locked.

(Example of change)
As described above, in the hybrid vehicle 5, when the R range is selected as the shift range, the driving force of the vehicle is smaller than when the D range is selected as the shift range. Therefore, when the R range is selected as the shift range, the control accelerator opening Acc * with respect to the same accelerator opening Acc is larger than when the D range is selected as the shift range. The eco-mode map for the extremely low vehicle speed range shown in FIG.

  FIG. 9 shows an example of an eco mode map for an extremely low vehicle speed range according to this modification. Referring to FIG. 9, in the eco-mode map for the extremely low vehicle speed range when the D range is selected as the shift range, the control accelerator opening Acc * is within the range of 0 to 100% with respect to the accelerator opening Acc. It is determined to have linearity. On the other hand, the eco-mode map for the extremely low vehicle speed range when the R range is selected as the shift range, the control accelerator opening Acc * for the same accelerator opening Acc is selected as the shift range. Is set to be larger than the control accelerator opening degree Acc * set to.

  One of these two eco-mode maps is selected in accordance with the driver's operation on a shift lever (not shown) when the vehicle speed V is within the extremely low vehicle speed range. The shift position SP of the shift lever is detected by the shift position sensor 48.

  According to this modified example, when the R range is selected as the shift range in the eco mode, the vehicle driving force with respect to the same accelerator operation amount is increased as compared with the case where the D range is selected as the shift range. be able to. Therefore, it is possible to prevent the wheel from being locked at a step or the like during reverse travel.

  In the above-described embodiment, a hybrid vehicle is illustrated as a representative example of the vehicle. However, the present invention has a normal mode corresponding to normal traveling and a vehicle driving force for the same accelerator operation amount smaller than that in the normal mode. Any one of the eco modes can be applied to a vehicle that can be selected by the driver. For example, the present invention can also be applied to ordinary vehicles, electric vehicles, fuel cell vehicles, and the like that use only the engine as a drive source. Further, when applied to a hybrid vehicle, a hybrid vehicle having a hybrid configuration different from the configuration of FIG. 1 (for example, a so-called series hybrid configuration or an electric distribution type hybrid configuration) may be used.

  In the above-described embodiment, the configuration in which the driving force smaller than that of the normal traveling is generated by selecting the eco mode as the traveling mode is exemplified. However, the present invention is a vehicle having an echo mode as one traveling mode. The present invention is not limited to this, and can be applied to a vehicle having a function of reducing the vehicle driving force from that during normal traveling in accordance with a situation where fuel efficiency is important.

  Further, the present invention provides a normal mode and a power mode in which the vehicle driving force for the same accelerator operation amount is larger than the normal mode as a vehicle configured to be able to select two driving modes having different vehicle driving force for the same accelerator operation amount. It is also possible to apply to a vehicle configured to be able to select either of the above. In such a vehicle, even when the normal mode is selected by the driver, in a scene where it is determined that there is a high possibility that the wheel will be locked, the same accelerator operation amount can be The vehicle driving force is set to be equal to the set vehicle driving force.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  5 Hybrid vehicle, 10 Battery, 12 Converter, 14, 22 Inverter, 20 Power conversion unit, 40 Handle, 44 Accelerator position sensor, 46 Brake pedal position sensor, 48 Shift position sensor, 51, 52 Rotation angle sensor, 70L, 70R Front wheel , 80L, 80R Rear wheel, 90 Power switch, 100 Vehicle speed sensor, 131, 136 Stator, 132, 137 Rotor, 133, 138 Stator core, 134, 139 Three-phase coil, 150 Crankshaft, 151, 162 Sun gear, 152, 168 Ring gear , 153, 164 Pinion gear, 154, 166 Planetary carrier, 155 Output member, 160 Output shaft, 170 Counter drive gear, 300 Lock detector, 310 Travel Mode selection unit, 320 charge / discharge control unit, 330 travel control unit, 340 distribution unit, 350 inverter control unit, 360 converter control unit, DEF differential gear, ENG engine, MG1, MG2 motor generator, RD reducer, RG power transmission Reduction gear.

Claims (5)

A vehicle having a first travel mode and a second travel mode in which the vehicle driving force for the same accelerator operation amount is smaller than the first travel mode,
An accelerator operation detection unit for detecting the driver's accelerator operation amount;
A driving force setting unit for setting a vehicle driving force based on the detected accelerator operation amount;
The driving force setting unit is configured to reduce the difference between the same accelerator operation amount and the vehicle driving force set in the first driving mode as the vehicle speed decreases in the second driving mode. A vehicle that sets the driving force. A vehicle speed detector for detecting the vehicle speed;
When the detected vehicle speed is lower than a predetermined threshold value in the second traveling mode, the driving force setting unit is configured to set a vehicle driving force that is set in the first traveling mode for the same accelerator operation amount. The vehicle according to claim 1, wherein the vehicle driving force is set to be equal. The vehicle is configured to travel forward by a vehicle driving force generated by an internal combustion engine and an electric motor, while traveling backward by generating a vehicle driving force only from the electric motor,
When the detected vehicle speed is lower than the predetermined threshold value in the second traveling mode, the driving force setting unit sets the vehicle driving force that is set in the first traveling mode with respect to the same accelerator operation amount. The vehicle according to claim 2, wherein a vehicle driving force when the vehicle travels backward is set as described above.   The vehicle according to claim 2, wherein the driving force setting unit sets the predetermined threshold based on a vehicle speed when the wheels are in a locked state. A vehicle control method comprising: a first travel mode; and a second travel mode in which a vehicle driving force with respect to the same accelerator operation amount is smaller than the first travel mode,
Steps for detecting a driver's accelerator operation amount;
A step for setting a vehicle driving force based on the detected accelerator operation amount,
In the setting step, the vehicle driving force is set so that the difference from the vehicle driving force set in the first traveling mode with respect to the same accelerator operation amount decreases as the vehicle speed decreases. Method.

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