JP2004257368A - Fuel cut controlling device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To widen an operation region, where fuel cut can be executed, as much as possible and widely improve fuel consumption. <P>SOLUTION: A motor control device 30 outputs an assist signal for an engine 1 to an engine control device 31 from a battery managing device 32 and effects assist control of the engine 1 so that the number of revolutions of the engine 1 is maintained at the number of revolutions of the engine at which a goal is set when a battery SO reaches a set value Sc1 or more and the running state of the engine 1 is in a region of an engine assist condition continuous to a region of a preset condition of reduction fuel cut of the engine. Further, the engine control device 31 executes fuel cut even in an operation region where a fuel cut condition to execute the reduction fuel cut described above in addition to normal reduction fuel cut is not established when an assist signal for the engine 1 is inputted from a motor control device 30. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a fuel cut control device for a vehicle including an engine that generates a driving force and an electric motor that can drive the engine together and can assist freely.
[0002]
[Prior art]
In recent years, various types of hybrid vehicles equipped with an electric motor in addition to an engine as a drive source for vehicle travel have been developed and put into practical use. As such a hybrid vehicle, for example, in Japanese Patent Application Laid-Open No. 2001-82218, a driving force is assisted by a motor after a deceleration fuel cut of the vehicle, and a decrease in engine speed after returning from the deceleration fuel cut and a shock at the time of re-acceleration are performed. Techniques for reducing are disclosed.
[0003]
[Patent Document 1]
JP-A-2001-82218
[Problems to be solved by the invention]
By the way, some hybrid vehicles as described above automatically stop the vehicle when the operation of the engine is unnecessary, such as when the vehicle is stopped while waiting for a signal, waiting for a train, waiting for a person, or the like. Some vehicles aim to improve fuel efficiency by performing an idle stop to restart the engine when the engine needs to be operated. However, when the vehicle is running in a suburb where there are few opportunities to stop, there is a problem that a great benefit of improving fuel efficiency cannot be obtained.
[0005]
On the other hand, in a vehicle having a deceleration fuel cut function as disclosed in the above-mentioned Patent Document 1, this deceleration fuel cut can benefit from improved fuel efficiency even if the frequency of idle stops is small, but further improved fuel efficiency is achieved. In order to achieve this, it is effective means to widen the deceleration fuel cut region and the period set according to the engine operation state such as the engine speed and the vehicle speed. However, if the deceleration fuel cut region is simply expanded to, for example, the region of the engine speed to a low rotation region, there is a possibility that the engine may stall when the connection between the drive system and the engine is interrupted. .
[0006]
The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a vehicle fuel cut control device that can expand a driving range in which a fuel cut can be performed as much as possible and can greatly improve fuel efficiency. .
[0007]
[Means for Solving the Problems]
According to one aspect of the present invention, there is provided a fuel cut control apparatus for a vehicle, comprising: an engine that generates a driving force; and an electric motor that is capable of driving the engine together and that can be freely assisted. In the device, a fuel cut condition determining means for determining whether a preset fuel cut condition of the engine is satisfied, and a preset engine assist condition for assisting the engine with the electric motor are provided. Assist condition determining means for determining whether or not the condition is satisfied; assist executing means for driving the electric motor to assist the engine when the engine assist condition is satisfied; the fuel cut condition and the engine assist condition If at least one of the conditions is satisfied, the fuel cut for the engine is executed. Is characterized in that a fuel cut means that.
[0008]
According to a second aspect of the present invention, in the vehicle fuel cut control apparatus according to the first aspect, the fuel cut condition is set to include a predetermined region of an engine operating state. At the same time, the engine assist condition is set continuously to the fuel cut condition region.
[0009]
Further, according to a third aspect of the present invention, in the vehicle fuel cut control apparatus according to the first or second aspect, the remaining capacity of the battery that supplies power to the electric motor is estimated. A battery remaining capacity estimating means is provided, and when the remaining capacity of the battery is lower than a set value, the engine assist condition is not satisfied and the driving of the electric motor is prohibited.
[0010]
That is, in the fuel cut control device for a vehicle according to the first aspect, the fuel cut condition determining means determines whether a preset fuel cut condition of the engine is satisfied, and the assist condition determining means turns the engine on. It is determined whether or not a preset engine assist condition for assisting with the electric motor is satisfied. Then, the assist execution means drives the electric motor to assist the engine when the engine assist condition is satisfied. Further, the fuel cut execution means executes the fuel cut for the engine when at least one of the fuel cut condition and the engine assist condition is satisfied. For this reason, the operating range of the engine that executes the fuel cut is expanded, and it is possible to significantly improve the fuel efficiency.
[0011]
In this case, as described in claim 2, the fuel cut condition is set so as to have a predetermined region of the engine operating state, and the engine assist condition is set continuously to the region of the fuel cut condition.
[0012]
Further, according to the third aspect of the present invention, if a battery remaining capacity estimating means for estimating the remaining capacity of the battery for supplying electric power to the electric motor is provided, a state where the remaining capacity of the battery falls below the set value is obtained. It is desirable that the driving of the electric motor is prohibited as the engine assist condition is not satisfied.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 3 show an embodiment of the present invention, FIG. 1 is a schematic explanatory view of an entire vehicle equipped with a fuel cut control device, FIG. 2 is a flowchart of engine assist control, and FIG. 3 is a flowchart of fuel cut control. It is.
[0014]
In FIG. 1, reference numeral 1 denotes an engine disposed in a front part of the vehicle, and a driving force from the engine 1 is transmitted to an transfer 3 from an automatic transmission (including a torque converter and the like) 2 behind the engine 1. .
[0015]
Further, the driving force transmitted to the transfer 3 is input to a rear wheel final reduction gear 7 via a rear drive shaft 4, a propeller shaft 5, and a drive pinion shaft 6, while a reduction drive gear, a reduction driven gear, and a front It is input to the front wheel final reduction gear (the front drive system is not shown) via the drive shaft.
[0016]
The driving force input to the rear wheel final reduction gear 7 is transmitted to the left rear wheel 9rl via the rear wheel left drive shaft 8rl and to the right rear wheel 9rr via the rear wheel right drive shaft 8rr. The driving force input to the front wheel final reduction gear is transmitted to the left front wheel 9fl via the front wheel left drive shaft 8fl and to the right front wheel 9fr via the front wheel right drive shaft 8fr.
[0017]
Next, each electronic system mounted on the vehicle will be described.
The vehicle has two voltage systems, a high voltage system of 42V and a low voltage system of 14V.
[0018]
Reference numeral 11 denotes an inverter device. The inverter device 11 generates electric power by rotating a pulley 14 at the end of a rotating shaft via a belt 13 by a crank sprocket 12 of the engine 1 to generate electric power. The motor / generator 15 which starts the engine 1 at the time of starting or the like, and performs engine assist control for driving and assisting the engine 1 together as necessary (according to a flowchart of FIG. 2 described later) is electrically connected. Have been.
[0019]
The inverter device 11 is connected to a 42 V system wiring connected to a chargeable / dischargeable 36 V battery 16. The 42 V system wiring includes a starter motor 17 used only at the first engine start, and a power supply by an electric motor. The steering device 18 and the like are connected.
[0020]
A 42-V wiring is connected to the side surface of the inverter device 11, and a DC-DC converter 19 that converts a 42-V voltage to a 14-V voltage is provided substantially integrally therewith. The wiring connected to the DC-DC converter 19 is connected to a chargeable / dischargeable 12V battery 20, and to other various lamps, audio, and a 14V load 21 such as each control device described later.
[0021]
The vehicle is equipped with a motor control device 30 that causes the motor / generator 15 to execute automatic stop / restart control of the vehicle and assist control for the engine 1. The motor control device 30 includes a fuel cut control in the engine 1. , An engine control device 31 for executing various known controls, a battery management device 32 for mainly managing the charge state and the discharge state of the 36V battery 16, and the like, for example, are one of ISO standard protocols as a vehicle communication network. Are connected by a CAN (Controller Area Network) or the like.
[0022]
Connected to the motor control device 30 are a brake pedal depression amount sensor 42 that detects a depression stroke of a brake pedal 41 (a sensor that detects brake oil pressure) and an accelerator pedal depression amount sensor 44 that detects a depression stroke of an accelerator pedal 43. Have been. The motor control device 30 includes a steering wheel angle sensor 45 that detects a steering wheel angle θH, a vehicle speed sensor 46 that detects a vehicle speed V, and selected shift positions (P, R, N, D, third speed, second speed, and first speed). A shift position switch 47 for detecting each speed range (speed range), an engine speed sensor 48 for detecting the engine speed NE, and the like are connected. The signals obtained by these switches and sensors are shared especially by the motor control device 30 and the engine control device 31.
[0023]
Then, the motor control device 30 determines whether or not a preset engine automatic stop condition is satisfied based on information obtained from these switches and sensors, and the engine automatic stop condition is satisfied. In this case, a signal is output to the engine control device 31 to execute an idle stop for automatically stopping the engine 1.
[0024]
Further, when the engine automatic stop condition is not satisfied in the idle stop state, the motor control device 30 outputs a signal to the engine control device 31 and the inverter device 11 to drive the motor / generator 15, and the engine 1 Is restarted. Here, the engine automatic stop condition is, for example, that the brake pedal 41 is depressed, the accelerator pedal 43 is not depressed, and the shift position is P, N, D, 3rd, 2nd, or 1st speed. In this case, the vehicle speed V is substantially zero and there is no idle stop prohibition command from the battery management device 32.
[0025]
Further, the motor control device 30 performs a predetermined regeneration condition (for example, when the accelerator pedal 43 is not depressed, the engine speed NE is 1000 rpm or more, the vehicle speed V is 40 km / h or more, When the condition that the engine 1 is connected and the fuel is not consumed is satisfied, a regeneration command is output to the battery management device 32.
[0026]
Further, the motor control device 30 determines from the battery management device 32 that the remaining battery capacity (battery SOC) is equal to or greater than the set value Sc1 (for example, 60%) and the operating state of the engine 1 is in a predetermined engine assist condition range. In order to maintain the engine speed at the target engine speed, an assist signal for the engine 1 is output to the engine control device 31 and the engine 1 is assist-controlled.
[0027]
The engine assist condition is set so as to overlap and continue with an area of an engine operation state of a fuel cut condition for executing a later-described deceleration fuel cut of the engine 1. The vehicle speed is 1400 rpm or less, the vehicle speed is 50 km / h or less, and the termination condition is set in advance so that the vehicle speed is 20 km / h or less. At this time, the reason why the engine speed is not defined in the termination condition is that the engine speed is maintained at the target speed (for example, 1200 rpm: higher than the idle speed) by the engine assist by the motor / generator 15. is there. As described above, the motor control device 30 is configured to have functions as assist condition determination means and assist execution means.
[0028]
The engine control device 31 executes the fuel cut in various engine operation states. In particular, when the deceleration fuel cut is described in detail, for example, the accelerator is in an OFF state, the vehicle speed is 50 km / h or more, and the engine is stopped. When the rotation speed is 1350 rpm or more, the deceleration fuel cut is executed. Further, when the assist signal of the engine 1 is input from the motor control device 30, the fuel cut is executed even in the operation region where the fuel cut condition for executing the above-described deceleration fuel cut is not satisfied. That is, the engine control device 31 is configured to have functions as fuel cut condition determination means and fuel cut execution means.
[0029]
The battery management device 32 includes a battery temperature sensor 51 for detecting the battery temperature TBa of the 36V battery 16, a battery voltmeter 52 for detecting the battery voltage VBa, and a battery current for managing the charge state and the discharge state of the 36V battery 16. A battery ammeter 53 for detecting IBa is connected. Then, the state of the 36V battery 16 is estimated from these pieces of information, and in some cases (when the remaining battery capacity is estimated to be low), an idle stop prohibition command or the like is output to the idle stop control device 30. The battery management device 32 also charges the inverter device 11 when charging the 36V battery 16 in consideration of the state of the 36V battery 16 and a regeneration command input from the idle stop control device 30. And outputs a target voltage value (including without charging) according to various situations.
[0030]
Further, in order to detect the battery SOC, the battery management device 32 measures a current value IBa flowing into the 36V battery 16 by increasing the voltage at predetermined time intervals or at predetermined traveling distances, for example. The battery SOC is estimated from IBa. The value of the battery SOC is also output to the motor control device 30. That is, the battery management device 32 has a function as a battery remaining capacity estimation unit.
[0031]
Next, the engine assist control in the motor control device 30 will be described with reference to the flowchart of FIG. First, in step (hereinafter abbreviated as "S") 101, parameters required for control are read, and the process proceeds to S102, where it is determined whether or not the battery SOC is equal to or greater than a preset value Sc1 (for example, 60%).
[0032]
As a result of the determination in S102, when it is determined that the battery SOC is less than Sc1 (battery SOC <Sc1), the process proceeds to S103, and it is determined whether or not the engine assist flag FM is set (FM = 1). The engine assist flag FM is set when the motor / generator 15 is assisting the engine 1, and is cleared when the motor / generator 15 is not assisting.
[0033]
If the result of determination in S103 is that the engine assist flag FM is cleared (FM = 0), the program exits the program as it is, and if the engine assist flag FM is set (FM = 1), Proceeding to S104, the assist for the engine 1 ends, and proceeding to S105, the engine assist flag FM is cleared (FM = 0), and the program exits.
[0034]
On the other hand, when the battery SOC is determined to be equal to or higher than Sc1 as a result of the determination in S102 (battery SOC ≧ Sc1), the process proceeds to S106, in which the engine start condition of the engine assist condition, that is, the engine speed is 1400 rpm or less, and It is determined whether or not the condition that the vehicle speed is 50 km / h or less is satisfied. If the condition is not satisfied, the process proceeds to the above-described processing from S103. If the assist start condition is satisfied, the process proceeds to S107. Proceed to.
[0035]
In S107, it is determined whether or not an assist end condition of the engine assist condition, that is, a condition that the vehicle speed is equal to or less than 20 km / h is satisfied. If the assist end condition is satisfied when the vehicle speed is equal to or less than 20 km / h, the above-described condition is satisfied. The process proceeds to S103 and subsequent steps. If the assist end condition is not satisfied, the process proceeds to S108.
[0036]
Then, in S108, the engine assist flag FM is set (FM = 1), and in S109, the motor / generator 15 is set to the target engine speed by the constant speed control or the constant torque control. Is controlled to a value in the vicinity of 1200 rpm, and the program exits.
[0037]
Next, the fuel cut control executed by the engine control device 31 will be described with reference to the flowchart of FIG. First, parameters required for control are read in S201, and the process proceeds to S202, in which it is determined whether fuel cut conditions are satisfied. Here, the fuel cut condition is a condition for executing the above-described deceleration fuel cut, and is, for example, an accelerator OFF state, an operation state in which the vehicle speed is 50 km / h or more, and the engine speed is 1350 rpm or more. Or not.
[0038]
If the result of determination in S202 is that the fuel cut condition is not satisfied, the routine proceeds to S203, where the fuel cut flag FE is cleared (FE = 0), and the routine proceeds to S205. Proceeds to S204, sets the fuel cut flag FE (FE = 1), and proceeds to S205. That is, the fuel cut flag FE is a flag indicating that the fuel cut condition is satisfied.
[0039]
When the process proceeds from S203 or S204 to S205, it is determined whether the fuel cut flag FE is set, that is, whether the fuel cut condition is satisfied, and the fuel cut flag FE is set (if FE = 1). In step S207, the engine 1 is controlled to execute a known fuel cut, and the program exits.
[0040]
If the result of determination in S205 is that the fuel cut flag FE has been cleared (FE = 0), the routine proceeds to S206, where the engine assist flag FM is set, that is, the assist condition by the motor control device 30 is satisfied. If the engine assist flag FM is set (if FM = 1), the process proceeds to S207, where the engine 1 is controlled to execute a known fuel cut, and the program exits.
[0041]
If the result of determination in S206 is that the engine assist flag FM has been cleared (if FM = 0), the flow proceeds to S208, and the program exits without executing fuel cut.
[0042]
As described above, according to the present embodiment, in addition to the normal deceleration fuel cut condition, the fuel cut is executed also in the engine operation region where the assist condition by the motor control device 30 that is continuous with this condition is satisfied. While maintaining the engine speed appropriately, it is possible to significantly improve fuel efficiency by fuel cut.
[0043]
【The invention's effect】
As described above, according to the present invention, there is an excellent effect that the operating range in which the fuel cut can be performed is expanded as much as possible, and it is possible to greatly improve the fuel efficiency.
[Brief description of the drawings]
FIG. 1 is a schematic explanatory view of an entire vehicle equipped with a fuel cut control device. FIG. 2 is a flowchart of engine assist control. FIG. 3 is a flowchart of fuel cut control.
1 engine 11 inverter device 15 motor / generator (electric motor)
16 36V battery 30 Motor control device (assist condition determining means, assist executing means)
31 Engine control device (fuel cut condition determination means, fuel cut execution means)
32 Battery management device (remaining battery capacity estimation means)
46 Vehicle speed sensor 48 Engine speed sensor

Claims (3)

A fuel cut control device for a vehicle including an engine that generates a driving force and an electric motor that is capable of driving the engine together and freely assisting,
Fuel cut condition determining means for determining whether a preset fuel cut condition of the engine is satisfied,
Assist condition determining means for determining whether a preset engine assist condition for assisting the engine with the electric motor is satisfied,
Assist executing means for driving the electric motor to assist the engine when the engine assist condition is satisfied;
Fuel cut execution means for executing a fuel cut on the engine when at least one of the fuel cut condition and the engine assist condition is satisfied,
A fuel cut control device for a vehicle, comprising: The vehicle according to claim 1, wherein the fuel cut condition is set to include a predetermined region of an engine operating state, and the engine assist condition is set to be continuous with the region of the fuel cut condition. Fuel cut control device. Battery residual capacity estimating means for estimating the residual capacity of the battery that supplies power to the electric motor,
3. The fuel cut control device for a vehicle according to claim 1, wherein when the state of charge of the battery falls below a set value, the driving of the electric motor is prohibited as the engine assist condition is not satisfied.

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