JP4298937B2 - Vehicle control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a control device for a vehicle such as an automobile, and more particularly to a control device for a vehicle having a fuel injection supply type internal combustion engine and an electric motor for starting the engine.
[0002]
[Prior art]
In a fuel injection supply type internal combustion engine, when fuel injection is performed in the exhaust stroke while the internal combustion engine is cold, such as during cold start, the fuel condenses in the intake pipe and adheres to the wall of the intake passage and stays there. Since the fuel supply performance to the cylinder deteriorates, as shown in Japanese Patent No. 256974, as the prior art, when the internal combustion engine is in a cold state, the fuel flows in the intake stroke with the air flow to the cylinder To improve the fuel supply performance to the cylinder, capture the temperature of the internal combustion engine with the cooling water temperature, and shift the fuel injection timing from the intake stroke to the exhaust stroke in accordance with the rise in the cooling water temperature. There are things that improve characteristics and fuel consumption.
[0003]
Further, in a hybrid vehicle having an internal combustion engine for driving the vehicle and an electric motor, as described in JP-A-9-184439, when the amount of fuel adhering to the wall surface is unstable, the operating state of the internal combustion engine Is prohibited from being switched from the operation mode by the internal combustion engine to the operation mode by the electric motor, and this prohibition control ensures that the amount of fuel adhering to the wall surface is stable when the operation of the internal combustion engine is stopped. There are some which improve the accuracy of the air-fuel ratio control and improve the exhaust gas characteristics of the internal combustion engine by making it possible to easily predict the amount of fuel adhering to the wall surface at the time of restart.
[0004]
As another prior art made in view of the problem equivalent to the above problem in a hybrid vehicle, as shown in Japanese Patent Laid-Open No. 11-210521, in a direct injection internal combustion engine of in-cylinder fuel injection, In the intake stroke, the fuel is changed between immediately after the cold start and after a lapse of a predetermined time as shown in Japanese Patent Laid-Open No. 11-50893. Some have switched the injection mode between intake synchronous injection and intake asynchronous injection.
[0005]
[Problems to be solved by the invention]
By the way, when the engine is cold, injecting fuel in the intake stroke with air flow to the cylinder improves the fuel supply performance to the cylinder, but increases the amount of hydrocarbon emissions due to insufficient mixing of fuel and air. Therefore, the fuel injection mode should be terminated as soon as possible and the fuel injection timing should be shifted to the exhaust stroke.
[0006]
Further, in the hybrid vehicle, because the amount of fuel adhering to the wall surface is in an unstable state, if the operation state of the internal combustion engine is prohibited and switching from the operation mode by the internal combustion engine to the operation mode by the electric motor is prohibited, Improvement in exhaust performance will be impaired.
[0007]
The present invention has been made paying attention to the above-described problems. The object of the present invention is to promptly raise the wall surface temperature of the internal combustion engine after the engine is started to thereby adjust the fuel injection timing (start timing of fuel injection). The purpose of this invention is to provide a vehicle control device that can shift to the exhaust stroke more quickly than the intake stroke and improve fuel efficiency, exhaust and power performance, and in particular, a hybrid that uses an electric motor that can also be used for acceleration assist to start an internal combustion engine. In the case of a vehicle, attention is paid to the fact that it is possible to shorten the rotation speed increase time of the internal combustion engine at start-up and the wall surface temperature increase time of the internal combustion engine by pumping.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, a control apparatus for a vehicle according to the present invention includes a fuel injection means for injecting and supplying fuel to each cylinder, an internal combustion engine for driving the vehicle, an electric motor for starting the internal combustion engine, A battery for supplying electric power to the electric motor, and at the time of starting the engine, the electric motor is pumped to drive the internal combustion engine, and when the rotational speed of the internal combustion engine reaches a predetermined set value, the fuel injection timing of the intake stroke is Fuel injection control for starting fuel injection by the fuel injection means is performed.
[0009]
According to the vehicle control apparatus of the present invention, when the internal combustion engine is pumped by the electric motor when the engine is started, the rise time of the wall surface temperature of the internal combustion engine is shortened, and the engine speed reaches a predetermined set value, the intake stroke is reduced. Fuel injection by the fuel injection means is started at the fuel injection timing.
The vehicle control apparatus according to the present invention further counts the number of engine revolutions or the number of fuel injections of the internal combustion engine, and changes the fuel injection timing from the intake stroke to the exhaust stroke according to the count value of the number of engine revolutions or the number of fuel injections. The fuel injection timing control for shifting is performed.
[0010]
Since the number of engine revolutions and the number of fuel injections of the internal combustion engine have a correlation with the wall surface temperature of the internal combustion engine, the internal combustion engine is changed by changing the fuel injection timing from the intake stroke to the exhaust stroke according to these count values. The fuel injection timing appropriately shifts from the intake stroke to the exhaust stroke in accordance with the rise in the wall temperature.
Further, the vehicle control apparatus according to the present invention detects the engine warm-up state from the coolant temperature of the internal combustion engine and the like, and the fuel injection timing shifts from the intake stroke to the exhaust stroke as the engine warm-up state progresses. Timing control can also be performed.
[0011]
In order to achieve the above object, a vehicle control apparatus according to the present invention includes a fuel injection means for injecting and supplying fuel to each cylinder, an internal combustion engine for driving the vehicle, and an electric motor for starting the internal combustion engine. And a battery for supplying electric power to the electric motor, wherein the internal combustion engine is pumped by the electric motor when the engine is started, and the rotational speed of the internal combustion engine becomes a predetermined set value, and When the number of engine revolutions of the internal combustion engine reaches a predetermined set value, fuel injection control for starting fuel injection by the fuel injection means is performed.
[0012]
According to the vehicle control apparatus of the present invention, the internal combustion engine is pumped and driven by the electric motor when the engine is started, the rise time of the wall surface temperature of the internal combustion engine is shortened, the engine speed becomes a predetermined set value, and the internal combustion engine is When the number of engine revolutions of the engine reaches a predetermined set value, fuel injection by the fuel injection means is started.
[0013]
The vehicle control apparatus according to the present invention further detects the engine warm-up state from the coolant temperature of the internal combustion engine, and reduces the set value of the engine speed at which fuel injection is started as the engine warm-up state progresses. Therefore, the set value of the number of engine revolutions at which fuel injection is started can be set appropriately according to the engine warm-up state without excess or deficiency.
In addition, the vehicle control apparatus according to the present invention detects the remaining charge of the battery in order to secure electric power of the motor, and when the remaining charge is equal to or less than a predetermined set value, the internal combustion engine by the motor. The fuel injection control for prohibiting the pumping drive and starting the fuel injection by the fuel injection means is performed.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 shows a main configuration of a hybrid vehicle incorporating a vehicle control device according to an embodiment of the present invention.
[0015]
The hybrid vehicle has an internal combustion engine (engine) 1 and a motor generator (hereinafter referred to as MG) 2 which is a rotating electric machine, and these are used as power sources to drive wheels 5 via a clutch 3 and a transmission 4. To communicate.
A hybrid control unit (HCU) 6, which is a vehicle control unit, starts and stops the hybrid vehicle system based on a signal from the key switch 7, and torque required for the wheels 5 according to operation signals from the accelerator pedal 8 and the brake pedal 9. Is output to the control device (ECU) 10 of the engine 1, the inverter 11 that controls the MG 2, and the clutch 3.
[0016]
The MG 2 uses a battery 12, which is a secondary battery, as a power source. The electric energy of the battery 12 is converted into alternating current by the inverter 11 and applied to the MG 2, so that the MG 2 generates a driving force and is connected via the belt 13. The engine 1 is started and the wheels 5 are driven.
[0017]
The battery 12 is different from a 12V battery that is a power source of the HCU 6 or the like, and is a 42V battery in the present embodiment. The battery 12 rotates the MG 2 by the kinetic energy of the wheels 5 or the driving force of the engine 1 to generate electric power, and the inverter 11 is converted to direct current and charged.
[0018]
The ECU 10 that controls the engine instructs the throttle opening control device 16 to set the target opening degree of the throttle valve 15 that is obtained from the engine speed obtained from the signal from the crank angle sensor 14 and the torque command value from the HCU 6. To control. Further, the ECU 10 controls the fuel injection time of the fuel injection device 19 based on the engine coolant temperature detected by the water temperature sensor 17 and the detection signal of the oxygen concentration sensor 18 on the exhaust side.
[0019]
The fuel / air mixture is sucked into the combustion chamber 22 in the cylinder from the intake port 21 opened and closed by the intake valve 20 and ignited by the ignition device 23. The piston 24 is moved by the explosion energy of the air-fuel mixture to drive the wheels 5 and MG2. The combustion gas is discharged out of the combustion chamber 22 through an exhaust port 26 that is opened and closed by an exhaust valve 25, purified by a catalytic converter 27, and then discharged into the atmosphere.
[0020]
When the engine is started, the HCU 6 or the ECU 10 drives the internal combustion engine 1 with the MG 2 so that the rotational speed Ne of the internal combustion engine 1 becomes a predetermined setting value, and the number of rotations (pumping frequency) C of the internal combustion engine 1 is set to a predetermined value. If it becomes a value, fuel injection by the fuel injection device 19 is started at the fuel injection timing of the intake stroke (start timing of fuel injection), and the fuel injection timing is set according to the count value of the number of rotations C of the internal combustion engine 1. Injection timing control for shifting from the exhaust stroke to the exhaust stroke is performed. Note that when the remaining charge SOC of the battery 12 is equal to or less than a predetermined set value and the battery power is insufficient, the internal combustion engine 1 based on the MG2 is used regardless of the count value of the rotation speed Ne and the rotation speed C. Pumping drive is prohibited and fuel injection by the fuel injection device 19 is started. The number of rotations C of the internal combustion engine 1 can be measured from the output signal of the crank angle sensor 14.
[0021]
A hybrid vehicle control process implemented by executing software incorporated in the HCU 6 that gives command values to the ECU 10 and the inverter 11 will be described with reference to a flowchart shown in FIG. This process is executed every 10 ms.
[0022]
First, operation signals for the key switch 7, the accelerator pedal 8, and the brake pedal 9 are input (step 101).
Next, data such as a torque command value, a fuel injection prohibition command value, and a pumping loss control type is transmitted to the ECU 10 and the inverter 11. The ECU 10 receives data of the engine speed Ne, the engine coolant temperature Tw, and the engine speed C (step 102).
[0023]
Next, the operation mode is determined from the operation signal of the key switch 7 and the accelerator pedal 8, the engine coolant temperature Tw, and the complete explosion determination information (step 103).
When the engine coolant temperature Tw is low, the accelerator pedal 8 is depressed, or the brake pedal 9 is released, it is determined that the engine is in the “engine start mode” (Yes at step 104), and the engine start control is performed. Execute (Step S105).
[0024]
On the other hand, when the engine coolant temperature Tw is high, the accelerator pedal 8 is released, and the brake pedal 9 is depressed, it is determined that the engine is in the “idle stop mode” (Yes at step 106), Idle stop control is executed (step S107). In the idle stop control, a fuel injection permission flag described later is cleared, the operation of the internal combustion engine 1 is stopped, and fuel is not consumed.
[0025]
If none of them is satisfied (No at Step 106), the target torque To corresponding to the required driving force is determined from the opening of the accelerator pedal 8 (accelerator operation amount) and the engine speed Ne as the “running / power generation mode” (Step 106). 108). Next, based on the target torque To, a torque command value (target drive torque) TMo of MG2 and a torque command value (target drive torque) TEo of the internal combustion engine 1 are calculated, and the target torque To is distributed (step 109). .
Details of the engine start control will be described with reference to a flowchart shown in FIG.
[0026]
First, a rotational speed command value for MG2 (in this embodiment, for example, 1100 revolutions per minute) is set (step 201). Thereby, MG2 is rotationally driven with the rotational speed command value, and the internal combustion engine 1 is pumped.
Next, in this embodiment, the set value Co of the number of engine revolutions C permitting the start of fuel injection is set according to the physical quantity indicating the engine warm-up state, according to the engine coolant temperature Tw (step 202). In this embodiment, as shown in FIG. 4, the set value Co takes a value from 0 to 50, Co = 50 at an engine cooling water temperature Tw = −30 ° C., and an engine cooling water temperature Tw = 60 ° C. It is a linear function of Co = 0.
[0027]
Next, it is determined whether or not the number of engine revolutions C> the set value Co (step 203). If C> Co (Yes at Step 203), it is determined whether or not the engine speed Ne is greater than a preset speed Ns (for example, about 900 revolutions per minute) at which fuel injection is started (Step 204). ). If Ne> Ns (Yes at step 204), a fuel injection permission flag is set (step S205).
[0028]
When C> Co is not satisfied (No at Step 203), or when Ne> Ns is not satisfied (No at Step 204), it is determined whether or not the remaining charge SOC of the battery 2 is larger than the remaining charge SOCi for start determination (Step). 206). When the remaining charge SOC of the battery 2 is less than the remaining charge SOCi for start determination (No at Step 206), the fuel injection permission flag is set regardless of the engine speed C and the engine speed Ne at that time (No). Step S205).
On the other hand, if remaining charge SOC> start determination remaining amount SOCi (Yes at step 206), the fuel injection permission flag is cleared and the fuel injection is prohibited (step 207).
[0029]
With the above control, if the remaining charge SOC> the remaining start determination SOCi, the pumping of the internal combustion engine 1 by MG2 is performed until the two conditions C> Co and Ne> Ns are true.
[0030]
Next, an engine control process such as fuel injection, which is realized by executing software incorporated in the ECU 10, will be described with reference to a flowchart shown in FIG. This process is executed every 10 ms.
First, input processing of output signals from the engine rotation sensor 14, the water temperature sensor 17, and the oxygen concentration sensor 18 is performed (step 301).
[0031]
Next, data such as the engine speed Ne, the engine cooling water temperature Tw, the engine speed C, and the complete explosion determination information are transmitted to the HCU 6, and the operation mode, fuel injection permission / prohibition flag, internal combustion engine 1 are transmitted from the HCU 6. The data (information) such as the target drive torque TEo is received (step S302).
[0032]
Finally, the required air amount Qa is calculated from the information given from the HCU 6 and the detected engine speed Ne, and the opening of the throttle valve 15 is set via the throttle opening control device 16 so that the required air amount Qa is obtained. Is controlled (step S303).
Next, the fuel injection by the fuel injection device 19 is controlled (step 304), and then the opening and closing of the intake valve 20 and the exhaust valve 25 are controlled (step S305).
[0033]
Details of the fuel injection control will be described with reference to the flowchart shown in FIG. First, it is determined whether or not a fuel injection permission flag is set (step 401). If the fuel injection permission flag is set (Yes at step 401), the fuel injection pulse width Ti is calculated from the required air amount Qa, the engine speed Ne, the engine cooling water temperature Tw, and the signal of the oxygen concentration sensor 18 (step). S402).
[0034]
Next, the fuel injection start timing Tinjst is obtained from the fuel injection pulse width Ti, the engine speed Ne, the engine cooling water temperature Tw, and the engine speed C (step S403). The fuel injection start timing Tinjst is the time from the fuel injection reference point of each cylinder (for example, the bottom dead center delayed by 110 ° from the reference signal of each cylinder). When the engine speed C is 50 or less, the engine speed C As the engine temperature increases, the engine wall temperature rises. Therefore, when the engine cooling water temperature Tw is low, the fuel injection start timing Tinjst is decreased, and the fuel injection timing is shifted from the intake stroke side to the exhaust stroke side (step 403).
[0035]
Next, the fuel injection pulse width Ti and the fuel injection start timing Tinjst are set in the timer, and desired fuel injection is performed (step 404). Thus, the fuel injection start timing Tinjst for the internal combustion engine 1 with respect to the engine rotation frequency C (pumping frequency) and the engine cooling water temperature Tw is as shown in FIG.
If it is determined that fuel injection is prohibited (No at step 401), a timer value for prohibiting fuel injection is set.
[0036]
As described above, when the internal combustion engine 1 is started, the wall surface temperature of the internal combustion engine 1 can be increased by pumping by the MG 2 before the fuel injection is started, and the engine speed C or the engine cooling having a correlation with the wall surface temperature. With the water temperature Tw, the start timing of fuel injection can be quickly shifted from the intake stroke side to the exhaust stroke, and an effect of preventing deterioration in fuel consumption, exhaust, and power performance can be obtained.
[0037]
Further, the pumping by MG2 is limited to the case where the remaining amount SOC of the battery 12 is larger than the remaining amount SOCi for start determination necessary for starting the engine, thereby preventing the engine from being disabled due to running out of the battery.
Note that the number of engine revolutions C correlated with the wall surface temperature can be replaced with the number of fuel injections.
[0038]
【The invention's effect】
According to the vehicle control apparatus of the present invention, when the internal combustion engine is started, the wall surface temperature of the internal combustion engine is increased by pumping by an electric motor such as a motor generator before starting fuel injection, and the fuel injection start timing is set from the intake stroke side. By quickly shifting to the exhaust stroke, there is an effect of preventing deterioration in fuel consumption, exhaust and power performance.
[Brief description of the drawings]
FIG. 1 is a diagram showing a main configuration of a hybrid vehicle incorporating a vehicle control device as one embodiment of the present invention.
FIG. 2 is a flowchart of hybrid control in the hybrid vehicle control apparatus according to the embodiment of the present invention.
FIG. 3 is a flowchart showing details of engine start control by the vehicle control apparatus according to the present invention.
FIG. 4 is a graph showing the relationship between the engine coolant temperature and the set value of the number of engine revolutions.
FIG. 5 is a flowchart of engine control of a hybrid vehicle by the vehicle control apparatus according to the present invention.
FIG. 6 is a flowchart showing details of fuel injection control by the vehicle control apparatus according to the present invention.
FIG. 7 is a graph showing characteristics of fuel injection start timing.
[Explanation of symbols]
1 Internal combustion engine 2 Motor generator (MG)
5 Wheel 6 Hybrid control unit (HCU)
7 Key switch 8 Accelerator pedal 9 Brake pedal 10 Engine control unit (ECU)
11 Inverter 12 Battery 15 Throttle valve 16 Throttle opening control device 19 Fuel injection device 20 Intake valve 22 Combustion chamber 23 Ignition device 24 Piston 25 Exhaust valve

Claims (3)

A vehicle control apparatus comprising: an internal combustion engine that has fuel injection means for injecting and supplying fuel to each cylinder, and that drives the vehicle to travel; an electric motor that starts the internal combustion engine; and a battery that supplies electric power to the electric motor. In
At the time of cold engine start, the internal combustion engine is pumped by the electric motor, the number of revolutions of the internal combustion engine becomes a predetermined set value, and the number of revolutions of the internal combustion engine by the pumping drive indicates the engine warm-up state if the set value in accordance with, and characterized in that said fuel injection means the fuel injection to start by, according to the rotation number of the previous SL engine shifts the fuel injection timing from the intake stroke to the exhaust stroke A vehicle control device.   The engine warm-up state is detected from a coolant temperature of the internal combustion engine, and the set value of the number of rotations at which fuel injection is started is reduced as the engine warm-up state proceeds. Vehicle control device.   Fuel injection for detecting the remaining charge of the battery and prohibiting pumping drive of the internal combustion engine by the electric motor and starting fuel injection by the fuel injection means when the remaining charge is less than a predetermined set value The vehicle control device according to claim 1, wherein control is performed.

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