JP2004218555A - Control device for hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress the occurrence of vibration following the start-up of an engine in a hybrid vehicle provided with an engine and a motor as a drive source and constituted to stop the engine at the stop of the vehicle and to start traveling by the motor. <P>SOLUTION: When an engine starting request occurs (S1), the valve timing of an intake valve is advanced to the maximum by a variable valve timing mechanism to maximize a valve overlap amount (S2), and a throttle valve is fully opened by a throttle motor (S3), to perform cranking in the reduced state of pumping resistance. When engine speed reaches a prescribed engine speed or more (S4), the valve overlap amount and throttle opening are returned to normal (S5, S6), and fuel injection to the engine is started (S7). <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a control device for a hybrid vehicle having an engine and a motor as drive sources, and more particularly, to control when starting the engine.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, hybrid vehicles having an engine and a motor as drive sources have been known (for example, see Patent Literature 1 and Non-Patent Literature 1).
[0003]
In the hybrid vehicle, when the vehicle is stopped, the engine, the generator, and the motor are both stopped, and when the vehicle starts, the vehicle is started to run by a motor having an advantageous torque characteristic. Then, the engine is quickly driven by using the generator driven by the engine as a starter. To start.
[0004]
Then, when the engine is started, by supplying the motor with the power generated by the generator, the motor driving force is added to the engine driving force to accelerate the engine. At the time of full-open acceleration, the driving power is also supplied from the battery to the motor.
[0005]
[Patent Document 1]
JP-A-10-288028 [Non-Patent Document 1]
Edited by Masayuki Okazawa, "Automotive Engineering June 1997", Railway Japan Co., Ltd., June 1, 1997, p38-p52
[0006]
[Problems to be solved by the invention]
By the way, in the hybrid vehicle as described above, the start and stop of the engine are frequently repeated on a congested road where the vehicle stops and starts repeatedly.
[0007]
Therefore, if the startability of the engine is poor, there is a problem that every time the engine is started (in other words, every time the vehicle starts), a large engine vibration is generated, which causes discomfort to the occupant of the vehicle.
[0008]
SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has an improved engine startability in a hybrid vehicle having a configuration in which an engine and a motor are provided as drive sources, the engine is stopped when the vehicle stops, and the motor starts running. Accordingly, it is an object to suppress the occurrence of vibration accompanying the engine start.
[0009]
[Means for Solving the Problems]
Therefore, according to the first aspect of the invention, when starting the engine, the fuel supply to the engine is stopped from the start of the engine until the engine rotation speed reaches a predetermined speed, and the pumping resistance of the engine is reduced. The structure was forcibly reduced.
[0010]
According to this configuration, when starting the engine, the fuel supply is stopped, and motoring is performed in a state where the pumping resistance is reduced. When the engine rotation speed reaches a predetermined speed, the pumping resistance is forcibly reduced. Is released, and fuel supply is started.
[0011]
Therefore, since the engine is motored with a small pumping resistance, the engine rotation speed smoothly increases to a high rotation speed, and the fuel supply is started after the engine rotation speed is sufficiently increased, so that the engine is started. The rotation speed continuously and smoothly increases, and engine vibration is suppressed.
[0012]
According to the second aspect of the present invention, the pumping resistance is forcibly reduced by forcibly increasing the valve overlap amount of the engine by controlling the valve timing.
[0013]
According to such a configuration, at the time of starting the engine, the valve overlap amount is increased by the retardation of the valve timing of the exhaust valve and / or the advancement of the valve timing of the intake valve, and the resistance at the time of inhaling air and / or the air , The pumping resistance in the intake stroke and / or the exhaust stroke is reduced.
[0014]
Therefore, in an engine including the variable valve timing mechanism, the pumping resistance can be easily reduced.
According to the third aspect of the invention, the pumping resistance is forcibly reduced by forcibly increasing the opening of the throttle valve by the actuator.
[0015]
According to such a configuration, when the engine is started, the opening degree of the throttle valve is increased, so that the resistance at the time of sucking air is reduced, and thus the pumping resistance in the intake stroke is reduced.
[0016]
Therefore, in an engine having an electronically controlled throttle that opens and closes the throttle valve with the actuator, the pumping resistance can be easily reduced.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described.
FIG. 1 is a schematic diagram of a hybrid system according to the present embodiment.
[0018]
In FIG. 1, the driving force of a gasoline engine 1 is divided by a power split mechanism 2 into a driving force of a driving wheel 3 and a driving force of a generator 4.
As the power split mechanism 2, a planetary gear device is used, and the power of the engine 1 is transmitted to a directly connected planetary carrier, and is distributed to a ring gear and a sun gear through a pinion gear.
[0019]
The rotating shaft of the ring gear is directly connected to the motor 5, and the driving force is transmitted to the driving wheels 3 through the speed reducer 8, while the rotating shaft of the sun gear is directly connected to the generator 4.
[0020]
The electric power generated by the generator 4 is directly used for driving the motor 5, is converted into direct current by the inverter 6, and is stored in the battery 7.
In the above configuration, when the vehicle stops, the engine 1, the generator 4, and the motor 5 are both stopped.
[0021]
At the time of starting, running is started by a motor having an advantageous torque characteristic. Immediately, the engine 1 is started using the generator 4 as a starter. At the time of normal running, the driving force of the engine 1 and the power generated by the generator 4 are increased. Is driven by the driving force of the motor 5 to which the motor 5 is supplied, and at the time of full-open acceleration, the driving power is also supplied from the battery 7 to the motor 5.
[0022]
In addition, at the time of deceleration, the driving wheels 3 drive the motor 5 so that the motor 5 functions as a generator, regenerative power is generated, and the regenerated energy is stored in the battery 7.
[0023]
FIG. 2 is a system configuration diagram of the engine 1.
An electronically controlled throttle 104 for opening and closing a throttle valve 103b by a throttle motor 103a (actuator) is interposed in an intake pipe 102 of the engine 1. The electronically controlled throttle 104 and the intake valve 105 allow a combustion chamber 106 to be opened. Air is inhaled.
[0024]
The combustion exhaust gas is exhausted from the combustion chamber 106 via an exhaust valve 107, purified by a front catalyst 108 and a rear catalyst 109, and then released into the atmosphere.
The intake valve 105 and the exhaust valve 107 are driven to open and close by cams provided on the exhaust camshaft 110 and the intake camshaft 134, respectively. The intake camshaft 134 is provided with a variable valve timing mechanism 113. ing.
[0025]
The variable valve timing mechanism 113 is a known mechanism that changes the valve phase of the intake valve 105 by changing the rotation phase of the intake camshaft 134 with respect to the crankshaft 120.
[0026]
In the present embodiment, the variable valve timing mechanism 113 is provided only on the intake side. However, the variable valve timing mechanism 113 may be provided on the exhaust side instead of the intake side or together with the intake side. .
[0027]
In addition, an electromagnetic fuel injection valve 131 is provided at the intake port 130 of each cylinder. When the fuel injection valve 131 is driven to open by an injection pulse signal, the fuel adjusted to a predetermined pressure is supplied to the intake valve 131 by an intake valve. Inject toward 105.
[0028]
A control unit 114 containing a microcomputer controls the electronic control throttle 104, the variable valve timing mechanism 113, and the fuel injection valve 131, and controls the engine rotation speed by controlling the rotation of the generator 4 by the inverter 6. .
[0029]
The control unit 114 receives detection signals from various sensors.
The various sensors include an air flow meter 115 that detects an intake air amount Q of the engine 1, an accelerator opening sensor APS116 that detects an accelerator opening, a crank angle sensor 117 that detects an angle of a crankshaft 120, and an opening of a throttle valve 103b. A throttle sensor 118 for detecting the degree TVO, a vehicle speed sensor 119 for detecting the vehicle speed, and the like are provided.
[0030]
The control unit 114 receives a battery voltage signal, a brake signal, and the like in addition to detection signals from the various sensors.
Then, when the driver steps on the accelerator pedal, the electronic control throttle 104 is opened according to the amount of depression, and at the same time, the engine speed is controlled by controlling the rotation speed of the generator 4.
[0031]
At this time, the ratio of distributing the engine power to the portion for directly driving the drive wheels 3 and the portion for driving the motor is also controlled, and the direct drive force of the engine 1 and the drive force of the motor 5 are combined to obtain the overall drive force. I do.
[0032]
Further, the control unit 114 performs control as shown in the flowchart of FIG. 3 when starting the engine 1 using the generator 4 as a starter.
[0033]
In the flowchart of FIG. 3, in step S1, it is determined whether there is a request to start the engine 1.
If there is an engine start request, the process proceeds to step S2.
[0034]
When there is an engine start request, the engine 1 is cranked using the generator 4 as a starter according to another control program.
In step S2, the valve timing of the intake valve 105 is advanced to the maximum by the variable valve timing mechanism 113 in order to forcibly maximize the valve overlap amount of the intake and exhaust valves.
[0035]
In the case where the variable valve timing mechanism 113 is provided only on the exhaust side, the valve timing of the exhaust valve 107 is retarded to the maximum to maximize the valve overlap amount. When the variable valve timing mechanism 113 is provided, the valve timing of the intake valve 105 is advanced to the maximum and the valve timing of the exhaust valve 107 is retarded to the maximum, thereby reducing the valve overlap amount. To the maximum.
[0036]
In the next step S3, the opening of the electronic control throttle 104 is forcibly controlled to the fully open WOT.
In the present embodiment, fuel injection is not performed even if the engine 1 rotates by cranking until fuel injection is started in step S7 described below.
[0037]
In step S4, it is determined whether or not the rotation speed (rpm) of the engine 1 has become equal to or higher than a predetermined rotation speed by cranking in a state where the valve overlap amount is maximized and the opening degree of the electronic control throttle 104 is set to the fully open WOT. Is determined.
[0038]
Here, the pumping resistance of the engine 1 is reduced by maximizing the valve overlap amount and controlling the opening of the electronic control throttle 104 to the fully open WOT.
[0039]
Accordingly, the engine speed (rpm) is smoothly and quickly increased to a higher speed by cranking.
Until it is determined in step S4 that the rotation speed (rpm) of the engine 1 has become equal to or higher than the predetermined rotation speed, the valve overlap amount is maximized and the opening of the electronic control throttle 104 is controlled to the fully open WOT. Therefore, the cranking is continued while the fuel injection is stopped.
[0040]
When it is determined in step S4 that the rotation speed (rpm) of the engine 1 has become equal to or higher than the predetermined rotation speed, the process proceeds to step S5, in which the valve timing (valve overlap amount) of the intake valve 105 is set to a normal value. In the next step S6, the opening of the electronic control throttle 104 is returned to the normal value.
[0041]
In step S7, fuel injection to the engine 1 is started, and the engine 1 is started.
At the time when the fuel injection is started in step S7, the rotation speed of the engine 1 has already been sufficiently increased, so that the engine 1 starts more smoothly than in the case where the fuel is injected from a low rotation speed.
[0042]
For this reason, it is possible to suppress the occurrence of engine vibration accompanying the start of the engine 1, and to avoid giving the driver discomfort even if the start and stop of the engine 1 are repeated.
[0043]
In the present embodiment, the pumping resistance during cranking is forcibly reduced by controlling the valve overlap amount to the maximum and controlling the opening of the electronic control throttle 104 to the fully open WOT. However, the pumping resistance may be reduced by only one of the valve overlap amount and the throttle opening.
[0044]
Further, if the valve operating mechanism of the intake valve 105 and the exhaust valve 107 is a mechanism (for example, a valve operating mechanism using an electromagnetic actuator) that can be held in an open state, a period from the start of cranking to a time when a predetermined number of rotations is reached is obtained. Alternatively, the intake and exhaust valves may be kept open.
[0045]
Further, the pumping resistance can be reduced by increasing the opening area of the intake / exhaust valve.
Here, technical ideas other than the claims that can be grasped from the above embodiment will be described below together with their effects.
(A) In the control device for a hybrid vehicle according to claim 1,
The engine includes a variable valve timing mechanism that varies a valve timing of an engine valve, and a throttle valve of the engine is configured to be opened and closed by an actuator,
The valve overlap amount is forcibly controlled to the maximum by controlling the valve timing, and the opening degree of the throttle valve is forcibly controlled to be fully opened by the actuator, thereby forcibly reducing the pumping resistance. Control device for a hybrid vehicle.
[0046]
According to such a configuration, by maximizing the valve overlap amount and the throttle opening, it is possible to minimize the pumping resistance in the engine including the variable valve timing mechanism and the throttle actuator.
[0047]
Therefore, the engine speed can be more smoothly started by maximizing the attained rotation speed by cranking.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram of a hybrid vehicle according to an embodiment.
FIG. 2 is a system configuration diagram of the engine shown in FIG. 1;
FIG. 3 is a flowchart showing engine start control according to the embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Engine, 2 ... Power distribution mechanism, 3 ... Drive wheel, 4 ... Generator, 5 ... Motor, 6 ... Inverter, 7 ... Battery, 8 ... Reduction gear, 103a ... Throttle motor (actuator), 103b ... Throttle valve, 104 ... Electronic control throttle, 105 ... Intake valve, 107 ... Exhaust valve, 113 ... Variable valve timing mechanism, 114 ... Control unit

Claims (3)

A hybrid vehicle having an engine and a motor as driving sources, stopping the engine when the vehicle stops, and starting running with the motor,
When starting the engine, fuel supply to the engine is stopped during a period from the start of the engine until the engine rotation speed reaches a predetermined speed, and the pumping resistance of the engine is forcibly reduced. Hybrid vehicle control device. The engine is provided with a variable valve timing mechanism for varying a valve timing of an engine valve, and forcibly increasing a valve overlap amount by controlling a valve timing to forcibly reduce a pumping resistance. The control device for a hybrid vehicle according to claim 1. 3. The pump valve according to claim 1, wherein a throttle valve of the engine is driven to be opened and closed by an actuator, and a pumping resistance is forcibly reduced by forcibly increasing an opening of the throttle valve. Hybrid vehicle control device.

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