JP2005320890A - Hybrid vehicle having engine/electric drive system separated - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To control impact and vibration to be generated on a wheel drive system or a vehicle body at a time of switch of an operation mode, by reducing or eliminating disturbance which the control of an internal combustion engine or a motor receives through on and off operation of the other when the operation mode is switched among drive by only the internal combustion engine, drive by only the motor and drive by both, in a hybrid vehicle. <P>SOLUTION: The internal combustion engine drives only either front wheels or rear wheels, and the motor drives only either the front wheels and the rear wheels in the hybrid vehicle. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a hybrid vehicle using an internal combustion engine and an electric motor as a vehicle drive source, and more particularly to a hybrid vehicle in which an engine drive system and an electric drive system are separated.

In a hybrid vehicle using an internal combustion engine and an electric motor as a vehicle drive source, an electric motor is provided for each of the front wheels and the rear wheels, and switching between two-wheel drive and four-wheel drive is performed according to the driving state of the vehicle and road conditions. It is described in Patent Documents 1 and 2 below. Among them, Patent Document 1 further performs control to apply driving force after the vehicle is moved backward to a predetermined vehicle speed or acceleration higher than zero when the vehicle starts on an uphill road, and the driver grasps the road gradient. It is described that the accelerator pedal can be depressed. Patent Document 2 describes that a target driving force is obtained based on a driving operation of a driver and a vehicle speed, and front wheel driving force and rear wheel driving force are controlled.
JP 2001-171377 A JP 2001-171378 A

Also, in hybrid vehicles, the road uphill slope is more suitable for switching control between the acceleration mode that operates the motor even during operation of the internal combustion engine to assist the output of the internal combustion engine and the cruise mode that does not operate the motor. Patent Document 3 below describes that control is performed to make it easy to enter the acceleration mode when the road is strong, and to make it difficult to enter the acceleration mode when the uphill slope of the road is weak. Further, Patent Documents 4 and 5 below describe that the degree of road surface gradient is obtained when descending a slope, and the degree of power regeneration is changed from the kinetic energy of the vehicle according to the obtained degree of slope. Among them, Patent Document 5 describes that the power generation efficiency of the generator is changed when the degree of power regeneration is changed according to the grade of the road surface. In Patent Document 6 below, the amount of energy that can be regenerated on the downhill road is calculated, and the amount of energy stored at the end of the downhill road is maximized based on the amount of charge stored in the battery and the information on the downhill road. It is described that the braking force of the generator on the downhill road is controlled.
JP-A-11-266507 JP 2000-102110 A JP 2000-217203 A JP 2001-54220 A

  The hybrid vehicle is operated by switching between three operation modes in which the driving wheels are driven only by the internal combustion engine or the electric motor or by both of them simultaneously. However, in the conventional hybrid vehicle, the same operation is performed. These drive wheels are driven by only the internal combustion engine, only the electric motor, or both. In that case, if the drive wheel and the motor are connected in series on both sides of the internal combustion engine, the internal combustion engine must be idled during the electric drive. The driving wheel is connected to one side of the sandwiching and the internal combustion engine is connected to the other side via a clutch, or the internal combustion engine is connected to one input end of a rotational power combining device such as a planetary gear device, An electric motor is connected to the other input end, a driving wheel is connected to the output end, and an appropriate clutch is combined with this to drive the driving wheel only by the internal combustion engine or only the electric motor or both. Yes.

  However, when the internal combustion engine and the electric motor are connected to the drive wheels directly or through a clutch or a rotational power synthesizer as described above, when the operation of either the internal combustion engine or the electric motor is turned on / off, the torque change is caused. The driving wheel connected to the large inertial mass of the vehicle body acts directly on the other as a reaction force support member, so the control of the internal combustion engine or electric motor is subject to considerable disturbance, and the wheel drive system and vehicle body are impacted when switching the operation mode. Or vibration may occur.

  In view of the above circumstances, the present invention reduces or eliminates the disturbance that is received by the control of the internal combustion engine or the electric motor when the operation mode of the hybrid vehicle is switched, and the impact and vibration are generated in the wheel drive system and the vehicle body when the operation mode is switched. The challenge is to provide a hybrid vehicle that is suppressed.

  In order to solve the above problems, the present invention provides a hybrid vehicle having an internal combustion engine and an electric motor as a vehicle drive source, and drives either one of the front wheels or the rear wheels only by the internal combustion engine, and The present invention proposes a hybrid vehicle characterized by being driven only by an electric motor.

  If the hybrid vehicle is configured so that either the front wheel or the rear wheel is driven only by the internal combustion engine and the other is driven only by the electric motor as described above, the hybrid vehicle is in a state where the internal combustion engine is stopped. When starting uphill, the internal combustion engine may be automatically started, and when the internal combustion engine is stopped and the vehicle starts on flat ground, if the accelerator opening is equal to or greater than a predetermined value, the vehicle speed is The internal combustion engine may be automatically started when a predetermined value that is not zero is reached.

  As described above, when the hybrid vehicle is configured so that either one of the front wheels and the rear wheels is driven only by the internal combustion engine and the other is driven only by the electric motor, both the internal combustion engine and the electric motor are front wheels or rear wheels. On the other hand, since the mutual interference of the torque between the internal combustion engine and the electric motor works only via a large inertial mass of the vehicle body between the front wheels and the rear wheels, the operation of the internal combustion engine and the electric motor is turned on and off. The vibration damping control according to the above is executed without receiving the interference of the torque change of the other electric motor or the internal combustion engine, so that a high vibration damping effect can be obtained.

  Conventionally, in a hybrid vehicle, when the internal combustion engine is in an electrically operated state, the vehicle is started in an electrically operated state even when starting on a flat ground or starting uphill. A large driving torque is temporarily required for starting the vehicle, and driving torque is insufficient for electric driving using only an electric motor, particularly for starting on an uphill or agile starting on a flat ground. If the internal combustion engine drives either the front wheel or the rear wheel, and the motor drives the other, a large inertial mass called a vehicle body is interposed between the two, so that there is no direct Even if the internal combustion engine is started simultaneously with the start of the vehicle, the effect of adding torque by the parallel operation of the internal combustion engine and the electric motor can be sufficiently exerted.

  FIG. 1 is a schematic diagram showing one embodiment of a wheel drive system of a hybrid vehicle according to the present invention. In the figure, 10 is a vehicle body, 12L and 12R are a pair of left and right front wheels, and 14L and 14R are a pair of left and right rear wheels. The front wheels 12L and 12R are driven from the internal combustion engine 16 via the transmission 18, axles 20L and 20R, and steering mechanisms 22L and 22R, respectively. Reference numeral 24 denotes a starter for starting the internal combustion engine, and reference numeral 26 denotes a generator that generates electric power by rotating the internal combustion engine and the axle 20R. The starter 24 is operated by a low-voltage (12 V in the illustrated example) battery 28, and the electric power generated by the generator 26 is stored in a high-voltage battery 30. The low voltage battery 28 is charged from the high voltage battery 30 via the DC / DC converter 32.

  The rear wheels 14L and 14R are driven by the motor generator 34 through the differential gear device 36 and the axles 38L and 38R, respectively, and the motor generator 34 is driven by the rear wheels 14L and 14R when the vehicle is braked. Is regenerated as electricity. The motor generator 34 is connected to the high voltage battery 30 via the inverter 40, is driven by the power from the high voltage battery 30, and generates regenerative power.

  From the internal combustion engine 16, the transmission 18, the DC / DC converter 32, the motor generator 34, and the inverter 40, signals indicating respective operation states are transmitted to an electronic vehicle operation control device (ECU) 42 provided with a microcomputer. At the same time, a signal for controlling the operation is sent from the electronic vehicle operation control device to each device. In addition, a signal indicating the charging state from the high voltage battery 30, a signal indicating the vehicle speed from the vehicle speed sensor 44, and a signal indicating the tilt angle in the front-rear direction of the vehicle body are sent from the tilt sensor 46 to the electronic vehicle operation control device 42. Although not shown in the figure, a signal relating to the depression state of the accelerator pedal from the accelerator sensor, a signal relating to the depression state of the brake pedal from the brake sensor, two-wheel drive and four-wheel drive from the two-wheel drive / four-wheel drive changeover switch (4WDS / W). Signals for switching between wheel drives are sent. The operation of the starter 24 and the generator 26 is controlled by a command signal from the electronic vehicle operation control device 42.

  The electronic vehicle operation control device 42 performs control calculation based on the control program incorporated therein according to the various signals sent to the electronic vehicle operation controller 42, and drives the vehicle with only the internal combustion engine or only the electric motor. Alternatively, when the operation mode is selected to drive both of them simultaneously, and the vehicle is driven only by the internal combustion engine, the internal combustion engine 16 is operated to drive only the pair of front wheels 12L and 12R, and the vehicle is driven only by the electric motor. When driving the motor, the motor generator 34 is operated to drive only the pair of rear wheels 14L and 14R. When the vehicle is driven by both the internal combustion engine and the motor, only the front wheels 12L and 12R are driven depending on the internal combustion engine. Driven, depending on the motor generator, only the rear wheels 14L, 14R are driven.

  FIG. 2 shows an example of the manner in which the operation of the internal combustion engine 16 and the motor generator 34 is controlled by the electronic vehicle operation control device 42 in the hybrid vehicle shown in FIG. When starting uphill, the internal combustion engine is automatically started, and when starting on flat ground with the internal combustion engine stopped, if the accelerator opening is greater than or equal to a predetermined value, the vehicle speed is not zero. 6 is a flowchart illustrating an example including automatically starting an internal combustion engine when a value is reached.

  When the operation of the vehicle is started, the control according to the illustrated flowchart is repeatedly executed at a cycle of several tens of milliseconds as part of the comprehensive computer control of the vehicle by the electronic vehicle operation control device 42.

  When the control is started, the data necessary for the control is read in step 10, and then it is determined in step 20 whether the internal combustion engine is operated (engine ON) based on the read data. Is done. If the answer is yes (Y), control proceeds to step 30 where the tilt sensor 46 determines whether the vehicle is uphill (uphill). If the answer is yes, control proceeds to step 40, where it is determined whether or not the accelerator opening Ac is equal to or greater than a certain predetermined relatively large opening Ac1. If the answer is yes, control proceeds to step 50 where, in addition to the operation of the internal combustion engine, the motor generator 34 is operated to assist the drive by the internal combustion engine (MG assist). If the answer to step 40 is no (N), MG assist is not performed.

  If the answer to step 30 is no, the control proceeds to step 60 to determine whether the vehicle is on a downhill (downhill). If the answer is yes, control proceeds to step 70 where the internal combustion engine is stopped (engine off). In this case, since the answer to step 20 is no in the next control cycle, the control proceeds to step 100 described later. When the answer to step 60 is no, that is, when the vehicle is on the flat ground, the control proceeds to step 80, where it is determined whether or not the brake is operated (brake ON). Proceeding to step 90, regeneration of electric power (MG regeneration) from vehicle inertia energy by the motor generator 34 is performed. If the answer to step 80 is no, step 90 is bypassed.

  If the answer to step 20 is no, the control proceeds to step 100 to determine whether the vehicle is on an uphill (uphill). If the answer is yes, control proceeds to step 110 where it is determined whether the brake is activated (brake ON). If the answer is no, control proceeds to step 120 where it is determined whether the vehicle is started. This determination may be made, for example, when the brake is not operated, the accelerator opening is equal to or greater than a predetermined value, and the vehicle speed is increasing from zero. If the answer to step 120 is yes, the control proceeds to step 130 and the internal combustion engine is immediately started (engine start).

  When the answer to step 110 is yes, the control proceeds to step 140 where the electric power from the vehicle kinetic energy is regenerated by the motor generator 34. When the answer to step 120 is no, that is, when the vehicle is on an uphill road, the brake is not operated, and the vehicle is not started, the control proceeds to step 150, and the charge amount Qb of the high voltage battery 30 is predetermined. It is determined whether or not the value is equal to or greater than Qb1. If the answer is yes, control proceeds to step 160 and electric operation is performed, but if the answer is no, control proceeds to step 170 and the internal combustion engine is started.

  If the answer to step 100 is no, control proceeds to step 180, where it is determined whether the vehicle is on a downhill (downhill). If the answer is yes, control proceeds to step 190 where it is determined whether the brake is activated. If the answer is yes, control proceeds to step 200 where the electric power from the vehicle kinetic energy by the motor generator 34 is regenerated. If the answer to step 190 is no, step 200 is bypassed.

  When the answer to step 180 is no, that is, when the vehicle is on the flat ground, the control proceeds to step 210 and it is determined whether or not the brake is operated. If the answer is yes, control proceeds to step 200 and the above-described MG regeneration control is performed.

  If the answer to step 210 is no, control proceeds to step 220 where it is determined whether the vehicle is started. The determination of the vehicle start at this time may be made in the same manner as described for step 120. If the answer is yes, control proceeds to step 230 where it is determined whether or not the accelerator opening Ac is greater than a relatively large predetermined value Ac2 that requires a quick start of the vehicle. If the answer is yes, control proceeds to step 240 where it is determined whether or not the vehicle speed V is greater than or equal to a predetermined value V1. If the answer is yes, control proceeds to step 250 and the internal combustion engine is started. Thus, when the vehicle is started on the flat ground, it is started when the accelerator opening is equal to or greater than the predetermined value, when the vehicle starts to travel to some extent, and when the vehicle is started up on the uphill. The start is smoother with a lot of space. When driving on flat ground, when the vehicle is not starting, or when the vehicle is starting, the answer is no in either step 230 or 240, the control proceeds to step 260, and the charge amount Qb of the high-voltage battery 30 is predetermined. It is determined whether or not the value is equal to or greater than Qb2, and if the answer is yes, the control proceeds to step 270 and electric operation is performed. If the answer is no, the control proceeds to step 250 and the internal combustion engine is turned on. It is started.

  While the present invention has been described in detail with respect to one embodiment and several aspects thereof, it will be apparent to those skilled in the art that various modifications can be made to the embodiment within the scope of the present invention. It will be clear.

BRIEF DESCRIPTION OF THE DRAWINGS Schematic which shows the wheel drive system of the hybrid vehicle by this invention about one embodiment. The flowchart which illustrates the driving | running control point of the hybrid vehicle by this invention in connection with an uphill, a downhill, and flat ground driving | running | working.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Car body, 12L, 12R ... Front wheel, 14L, 12R ... Rear wheel, 16 ... Internal combustion engine, 18 ... Transmission, 20L, 20R ... Axle, 22l, 22R ... Steering mechanism, 24 ... Starter, 26 ... Generator, 28 ... Low voltage battery, 30 ... High voltage battery, 32 ... DC / DC converter, 34 ... Motor generator, 36 ... Differential gear device, 38L, 38R ... Axle, 40 ... Inverter, 42 ... Electronic vehicle operation control device, 44 ... Vehicle speed sensor, 46 ... Inclination sensor

Claims (3)

  A hybrid vehicle using an internal combustion engine and an electric motor as a vehicle drive source, and either one of the front wheels and the rear wheels is driven only by the internal combustion engine, and the other is driven only by the electric motor. A featured hybrid vehicle.   2. The hybrid vehicle according to claim 1, wherein the internal combustion engine is automatically started when starting uphill while the internal combustion engine is stopped. When starting on a flat ground while the internal combustion engine is stopped, if the accelerator opening is equal to or greater than a predetermined value, the internal combustion engine is automatically started when the vehicle speed reaches a predetermined value that is not zero. The hybrid vehicle according to claim 1, wherein the vehicle is a hybrid vehicle.

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