JP2009126303A - Vehicle control unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve fuel saving and improvement in drivability of a hybrid vehicle. <P>SOLUTION: When the vehicle begins to travel, electric power accumulated in a battery 0 is supplied to a motor generator 2 and an engine 1 is assisted in compensating for acceleration. For the electric power consumed to assist in the acceleration, electric power is charged through exhaust gas power generation during a steady travel. After the charging state of the battery 0 recovers, the electric power generated through the exhaust gas power generation is supplied to a motor generator 2 as it is. Then the opening extent of a throttle is controlled according to the assist amount of the motor generator 2 to lower the engine output. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a control device mainly responsible for traveling control in a hybrid vehicle.

  Recently, hybrid vehicles using a combination of an engine and a motor generator as a power source have been developed. In a hybrid vehicle, a motor generator is operated as a generator during deceleration, and regeneration is performed in which mechanical energy is converted into electrical energy and stored.

The engine also dissipates thermal energy through exhaust of combustion gas. In order to recover and reuse this thermal energy, a turbocharger that drives a compressor via an exhaust gas turbine may be provided (see, for example, the following patent document).
JP 2006-170054 A

  In a vehicle having a light weight and a vehicle equipped with an engine having a small displacement, electric energy obtained by regenerative operation tends to be small, and the fuel saving effect is generally limited.

  When a turbocharger is attached to a gasoline engine, it is necessary to suppress the compression ratio as a countermeasure against knocking, and the efficiency is reduced accordingly.

  An object of the present invention made in view of the above is to improve fuel economy and drivability in a hybrid vehicle.

  In the present invention, an engine having a throttle whose electronic opening can be adjusted electronically, a turbine disposed in an exhaust passage of the engine, an exhaust gas generator that generates exhaust gas by driving the turbine with exhaust gas, Motor generator, a battery serving as a power source for the motor generator, and at least a part of the electric power generated by the exhaust gas generator when the engine is shifted from acceleration to steady running, the battery is charged, and the state of charge of the battery (State Of Charge) And a control means for assisting the engine by supplying only the electric power generated by the exhaust gas to the motor generator and further adjusting the throttle opening so as to reduce the engine output according to the assist amount. A control device was configured.

  At the start of traveling, the electric power stored in the battery is supplied to the motor generator, and the engine is assisted to compensate for acceleration. The electric power consumed by the acceleration assist is charged by exhaust gas power generation during steady driving. After the SOC of the battery is recovered, the power generated by the exhaust gas is supplied to the motor generator as it is. Then, the engine output is reduced according to the assist amount by the motor generator. As a result, fuel efficiency and drivability can be improved even for a relatively light vehicle or a vehicle equipped with a small displacement engine.

  Moreover, exhaust gas power generation can be effectively performed when the engine speed is higher than a certain level. That is, more power can be generated during high-speed cruise, and the motor generator can assist the engine. In conventional hybrid vehicles that place importance on regeneration during deceleration, sufficient regenerative power may not be obtained during high-speed cruise, and the SOC may decrease. However, the vehicle control device according to the present invention avoids this problem. it can.

  The control means is a state in which power is supplied from the battery to the motor generator in response to an increase in engine speed or exhaust gas power generation from the start of travel, a state in which power is supplied from the battery and the exhaust gas generator to the motor generator, Controls the transition from the exhaust gas generator to the state in which electric power is supplied to the motor generator, thereby promoting the use of electric power with low power generation cost.

  The control means causes the motor generator to assist the engine at the start of travel, and after shifting from acceleration to steady travel, charges the battery with the amount of power consumed by the assist. With such a configuration, it is possible to assist at the time of re-start after stopping or re-acceleration after deceleration, and fuel consumption in the engine can be reduced.

  The control means preferably performs regeneration by a motor generator if the battery is in a chargeable state when decelerating.

  The control means charges the battery with the electric power generated by the exhaust gas generator until reaching a predetermined first target capacity when shifting from acceleration to steady running, and uses the electric power regenerated by the motor generator when decelerating. The battery shall be charged until a higher second target capacity is reached. If the battery is fully charged during the exhaust gas power generation, a large exhaust gas resistance is generated in the exhaust gas generator and the turbine. Accordingly, the battery is charged to the first target capacity that is less than full charge during steady running, and then the generated power is exclusively used for assisting the engine, and the battery is charged to the second target capacity that is close to full charge by regenerative operation during deceleration.

  When the amount of change in the accelerator operation is large, the control means sets a larger amount for the motor generator to assist the engine at the start of traveling than when the change amount is small. When the change amount of the accelerator operation is large, it is expected that the arrival speed of the vehicle is increased, and that regenerative power is increased. Therefore, it is allowed to spend more electric power for assisting the engine than when the change amount of the accelerator operation is small (the arrival speed of the vehicle is low).

  In addition, when the change amount of the accelerator operation is large, the first target capacity is set to be smaller than that when the accelerator operation is small, so that the electric power generated by the exhaust gas during the steady running is supplied to the motor generator and the assist amount is increased. Good.

  According to the present invention, fuel efficiency and drivability are improved in a hybrid vehicle.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, the outline | summary of the hybrid vehicle in this embodiment is shown. This vehicle has both an engine 1 that is an internal combustion engine and a motor generator 2 that is an electric motor capable of generating electric power as driving sources for wheels.

  The engine 1 is a known gasoline engine or the like having a throttle whose electronic opening can be adjusted electronically, and transmits output torque to a drive wheel via a torque converter 3, a clutch 4 and a transmission 5. Similar to the engine 1, the torque converter 3, the clutch 4 and the transmission 5 can be appropriately employed as well.

  The motor generator 2 assists the engine 1 by receiving torque from the battery 0 and / or an exhaust gas generator 7 described later and outputting torque. Not only that, it is driven by the engine 1 or drive wheels and operates as a generator. Electric power generated by the regeneratively operated motor generator 2 is stored in the battery 0.

  The vehicle control unit 91 is an electronic control unit that controls the driving state of the entire vehicle. The electronic control unit includes a CPU, a RAM, a ROM, an I / O interface, etc., stores various control programs in the ROM, reads the programs from the ROM into the RAM, and decodes them by the CPU. 1 and the motor generator 2 are controlled. The electronic control unit also detects a sensor S1 that detects the amount of operation of the accelerator, a sensor S2 that detects whether the brake is operated, a sensor S3 that detects the number of revolutions of the engine 1, and a traveling speed of the vehicle. The sensor S4, the sensor S5 that detects the position of the shift position lever, the sensor S6 that detects information (current amount, etc.) for calculating the state of charge (SOC) of the battery 0 are connected.

  The engine control unit 92 receives a control command from the vehicle control unit 91, controls the opening of the throttle valve of the engine 1 and the fuel injection amount of the injector, and adjusts the output of the engine 1.

  The motor control unit 93 receives a control command from the vehicle control unit 91, controls the magnitude and frequency of the current flowing through the motor generator 2 via the inverter circuit, and adjusts the output and rotation speed of the motor generator 2. The motor control unit 93 also adjusts the amount by which the battery 0 is charged with the electric power generated by the motor generator 2 or the exhaust gas generator 7.

  The transmission control unit 94 receives the control command from the vehicle control unit 91 and controls the transmission 5.

  In addition, a turbine 6 is disposed in the exhaust passage 11 of the engine 1, and the exhaust gas generator 7 is driven by the turbine 6 to generate electric power. The turbine 6 and the exhaust gas generator 7 are connected via a reduction gear and a clutch 8.

  In the present embodiment, the vehicle control unit 91, the engine control unit 92, the motor control unit 93, the transmission control unit 94, etc. cooperate to exert the function as the control means 9 referred to in the present invention. The engine 1 and the motor generator 2 are controlled according to the control.

FIG. 2 shows the vehicle traveling speed associated with the control, the output of the engine 1 and the motor generator 2 (the thin solid line is the output of the engine 1, the thick solid line is the assist amount by the motor generator 2, and the thick broken line is the regeneration amount by the motor generator 2). The time series of the fluctuation | variation of the electric power generation amount of the exhaust gas generator 7, and SOC of the battery 0 is shown. First, in a period t ₁ from the start of running to the initial acceleration, the motor generator 2 receives power supply from the battery 0 and outputs torque to assist the engine 1. In the acceleration period t ₁ , the travel speed, the engine speed, and the exhaust pressure are low, so the amount of exhaust gas power generation is small or no power is generated, and the SOC decreases.

In the period t _{2 when the} traveling speed, the engine speed and the exhaust pressure increase and the amount of power generated by the exhaust gas generator 7 begins to increase, the motor generator 2 receives power supply from both the battery 0 and the exhaust gas generator 7. In the acceleration period t ₂ , the decrease in SOC is suppressed by the amount of power generated by exhaust gas power generation.

In the period t ₃ when the amount of power generated by the exhaust gas generator 7 becomes sufficiently large, the motor generator 2 receives power supply from only the exhaust gas generator 7. In the acceleration period t ₃ , the SOC does not decrease.

In the period t ₄ during which the vehicle shifts from acceleration to steady running, the running speed and the amount of exhaust gas power generation are substantially constant. In the steady running period t ₄ , part or all of the power generated by the exhaust gas is charged in the battery 0 and the rest is directed to the assist of the engine 1. While the SOC increases, the assist amount by the motor generator 2 is reduced compared to the period t ₃ .

In the steady running period t ₅ after the SOC has recovered to the predetermined target capacity (first target capacity), the power generated by the exhaust gas is exclusively used for assisting the engine 1. The first target capacity is, for example, a value obtained by subtracting the average of the charge amount obtained by one regenerative operation from the full charge amount, or a value about half of the full capacity of the battery 0. In steady running period t _5, the assist amount is increased by the motor generator 2, the output of the engine 1 is reduced instead.

In deceleration period t ₆ performs regenerative operation by motor generator 2, SOC to charge the battery 0 to recovery to a predetermined target volume (second target capacity). The second target capacity is the upper limit of charging and is higher than the first target capacity.

  3 and 4 show the procedure of processing executed by the control means 9. The control means 9 refers to the vehicle running speed, accelerator operation amount, brake operation ON / OFF, shift position, etc. via the sensors S4, S1, S2, S5, and accelerates whether the vehicle is currently stopped. It is determined whether the vehicle is traveling, steady traveling or decelerating (steps ST1 to ST3).

  When the vehicle is stopped, the SOC of the battery 0 is estimated based on the information obtained through the sensor S6. If the battery 0 is in a chargeable state, in other words, the SOC is less than the second target capacity. (Step ST7) The battery 0 is charged with the electric power generated by the exhaust gas generator 7 (Step ST8). Otherwise, the battery 0 is not charged (or exhaust gas power generation). However, when the amount of exhaust gas at idling is small, steps ST7 and ST8 need not be performed.

When the vehicle is accelerating, the SOC of the battery 0 is estimated based on the information obtained through the sensor S6. If the SOC is equal to or greater than a predetermined lower limit (step ST9), each of the battery 0 and the exhaust gas generator 7 is estimated. The motor generator 2 is supplied with power to drive it to assist the engine 1 (step ST10). Step ST10 corresponds to the period t ₁ to t ₃ in FIG. The amount of power supplied from the battery 0 depends on the amount of power generated by the exhaust gas generator 7, and the smaller the amount of exhaust gas power generated, the more power is consumed by the battery 0, and the smaller the amount of power generated by the exhaust gas is, the more power is consumed by the battery 0.

  Note that the amount by which the motor generator 2 assists the engine 1 in step ST10, that is, the output of the motor generator 2, is set to increase as the change amount of the accelerator operation detected through the sensor S1 increases. For example, a map that defines the relationship between the change amount of the accelerator operation and the assist amount is stored in the RAM or ROM of the vehicle control unit 91, the assist amount is determined based on the map, and the motor generator 2 is controlled.

  On the other hand, if the SOC is less than the lower limit, the motor generator 2 is not driven, and the engine is accelerated only by the engine output (step ST11). In step S11, the battery 0 is charged with the electric power generated by the exhaust gas generator 7 at the same time.

When the vehicle is traveling at a reduced speed, the SOC of the battery 0 is estimated based on the information obtained through the sensor S6. The generated power is charged in the battery 0 (step ST13). Step ST13 corresponds to the period t ₆ in FIG. In step S13, the battery 0 may be charged with the electric power generated by the exhaust gas generator 7 as well. If the SOC is equal to or greater than the second target capacity, the battery 0 is not charged (or regenerative operation, exhaust gas power generation).

When the vehicle is traveling steadily, the SOC of the battery 0 is estimated based on the information obtained through the sensor S6. If the SOC is less than the first target capacity (step ST4), the electric power generated by the exhaust gas generator 7 Is charged in the battery 0 (step ST6). At this time, a part of the electric power generated by the exhaust gas can be fed to the motor generator 2 to assist the engine 1. Step ST6 is applicable to the period t ₄ in FIG.

  Note that the first target capacity that is the determination condition in step ST4 is the amount of change in the accelerator operation detected through the sensor S1, the engine speed detected through the sensor S3, or the travel speed detected through the sensor S4. The larger the value, the larger the setting. For example, a map that defines the relationship between the change amount of the accelerator operation, the engine speed or the running speed and the first target capacity is stored in the RAM or ROM of the vehicle control unit 91, and the first target is based on the map. Determine capacity and make a decision.

On the other hand, if the SOC is equal to or greater than the first target capacity, the exhaust gas generator 7 supplies power to the motor generator 2 to drive the motor generator 2 to assist the engine 1 and to reduce the engine output according to the assist amount. The opening degree is controlled (step ST5). Step ST5 corresponds to a period t ₅ in FIG.

  Accordingly, the processing routine shown in FIGS. 3 and 4 is repeatedly executed.

  Incidentally, in the above processing procedure example, when the vehicle is not stopped, accelerated, or decelerated, it is determined that it is in steady running, but in addition to this, when the amount of change in torque is smaller than a predetermined threshold, When the change amount of the accelerator operation amount is smaller than a predetermined threshold value or when it is detected that the accelerator that has been depressed is slightly loosened, it can be determined that the vehicle is in steady running.

  According to the present embodiment, the engine 1 having a throttle whose electronic opening can be adjusted electronically, the turbine 6 disposed in the exhaust passage 11 of the engine 1, and the exhaust gas power generation by driving the turbine 6 with the exhaust gas. An exhaust gas generator 7, a motor generator 2 for traveling, a battery 0 serving as a power source of the motor generator 2, and at least a part of the electric power generated by the exhaust gas generator 7 when shifting from acceleration to steady running After charging the battery 0 and recovering the charged state of the battery 0, only the electric power generated by the exhaust gas is supplied to the motor generator 2 to assist the engine 1, and the throttle is further reduced according to the amount of assist. Since the vehicle control device comprising the control means 9 for adjusting the opening degree is configured, a relatively light vehicle and a small displacement engine Even equipped with a vehicle 1, it can be realized to improve the fuel economy and drivability. As the engine load increases, the rotation of the exhaust turbine 6 increases and the amount of power generation increases. As a result, the amount of assist by the motor generator 2 increases and the driving force increases. Therefore, an assist feeling proportional to the driver's accelerator operation can be obtained. In addition, it is possible to avoid the problem that the SOC is lowered because sufficient regenerative power cannot be obtained.

  The control means 9 supplies power from the battery 0 and the exhaust gas generator 7 to the motor generator 2 in a state in which power is supplied from the battery 0 to the motor generator 2 as the engine speed and exhaust gas power generation increase from the start of travel. Is controlled, and further, the state in which power is supplied from the exhaust gas generator 7 to the motor generator 2 is controlled, so that the use of electric power with low power generation cost can be promoted to further improve fuel efficiency.

  The control means 9 causes the motor generator 2 to assist the engine 1 at the start of travel, shifts from acceleration to steady travel, and then charges the battery 0 with the amount of power consumed by the assist. Is restored to the first target capacity, so that it is possible to assist at the time of re-start after stopping or at the time of re-acceleration after deceleration, and fuel consumption in the engine 1 can be reduced.

  Since the control means 9 performs regeneration by the motor generator 2 if the battery 0 is in a chargeable state when decelerating, the regenerated energy can be used for acceleration of re-start.

  The control means 9 charges the battery 0 with the electric power generated by the exhaust gas generator 7 until reaching a predetermined first target capacity when shifting from acceleration to steady running, and uses the power regenerated by the motor generator 2 when decelerating. Since the battery 0 is charged until the second target capacity higher than the first target capacity is reached, the battery 0 is fully charged during the exhaust gas power generation, and the exhaust gas generator 7 and the turbine 6 have a large exhaust gas resistance. It is possible to avoid problems that may occur.

  The control means 9 sets a larger amount for the motor generator 2 to assist the engine 1 at the start of traveling when the amount of change in the accelerator operation is large than when it is small, so that an appropriate amount corresponding to the required load is set. The engine assist can be performed.

  Further, when the change amount of the accelerator operation is large, the first target capacity is set to be smaller than that when the accelerator operation is small, so that the electric power generated by the exhaust gas during the steady running is supplied to the motor generator 2, that is, the assist amount is increased. This contributes to fuel efficiency during steady driving.

  The present invention is not limited to the embodiment described in detail above. For example, a turbocharger can be configured by connecting a compressor to a turbine and used in combination with exhaust gas power generation.

  Other specific configurations, processing procedures, and the like can be variously modified without departing from the spirit of the present invention.

The figure which shows schematic structure of the vehicle control apparatus of one Embodiment of this invention. The figure which shows the fluctuation | variations of the engine output in the driving | running | working process of a vehicle, a motor generator output, etc. The flowchart which shows the procedure of the process performed by a control means. The flowchart which shows the procedure of the process performed by a control means.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Engine 2 ... Motor generator 6 ... Turbine 7 ... Exhaust gas generator 9 ... Control means 0 ... Battery

Claims (8)

An engine with a throttle that can electronically adjust the opening;
A turbine disposed in the exhaust passage of the engine;
An exhaust gas generator that generates exhaust gas power by driving the turbine with exhaust gas;
A motor generator for traveling;
A battery that serves as a power source for the motor generator;
When shifting from acceleration to steady running, the battery is charged with at least part of the power generated by the exhaust gas generator, and after the battery is restored, only the power generated by the exhaust gas is supplied to the motor generator. And a control means for adjusting the throttle opening so as to reduce the engine output in accordance with the assist amount. The control means includes a state in which electric power is supplied from the battery to the motor generator as the engine speed increases from the start of traveling, a state in which electric power is supplied from the battery and the exhaust gas generator to the motor generator, and further an exhaust gas generator. The vehicle control device according to claim 1, wherein control is performed to shift to a state in which electric power is supplied from the motor to the motor generator. The control means includes a state in which power is supplied from the battery to the motor generator in response to an increase in the amount of exhaust gas power generated from the start of traveling, a state in which power is supplied from the battery and the exhaust gas generator to the motor generator, and further the exhaust gas generator. The vehicle control device according to claim 1, wherein control is performed to shift to a state in which electric power is supplied from the motor to the motor generator. 4. The vehicle control device according to claim 1, wherein the control means causes the motor generator to assist the engine at the start of travel, and after the transition from acceleration to steady travel, causes the battery to charge the amount of power consumed by the assist. . The vehicle control device according to claim 1, wherein the control means performs regeneration by a motor generator if the battery is in a chargeable state when decelerating. The control means charges the battery with the electric power generated by the exhaust gas generator until reaching a predetermined first target capacity when shifting from acceleration to steady running, and uses the electric power regenerated by the motor generator when decelerating. The vehicle control device according to claim 1, wherein the battery is charged until a higher second target capacity is reached. 7. The vehicle control device according to claim 6, wherein the control means sets a larger amount of the motor generator to assist the engine at the start of traveling when the change amount of the accelerator operation is large than when the change amount is small. The vehicle control device according to claim 6, wherein the control unit sets the first target capacity to be smaller when the change amount of the accelerator operation is large than when it is small.

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