JP2018162679A - Engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine control device which is improved in exhaust gas purification performance while suppressing fuel consumption at deceleration.SOLUTION: An engine control device 100 for controlling an engine 1 having a plurality of injectors 11 to 41 for injecting fuel according to injection signals to a plurality of cylinders 10 to 40 comprises: a fuel injection control part for imparting the injection signals to the injectors, and making them inject fuel; a fuel cut condition discrimination part for discriminating the sufficiency of the fuel cut condition; and a deceleration detection part for detecting the deceleration of a vehicle. When the sufficiency of the fuel cut condition is discriminated, the fuel injection control part performs fuel cut control, and increases the number of the cylinders at which the fuel cut condition is performed according to an increase of the deceleration.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an engine control apparatus that controls an engine mounted on a vehicle, and more particularly to an apparatus that improves exhaust gas purification performance while suppressing fuel consumption during deceleration.

Fuel cut control that temporarily stops fuel injection when coasting or braking the vehicle in an accelerator-off state for engines mounted on automobiles such as passenger cars for the purpose of improving fuel economy It is carried out.
As a conventional technology related to fuel cut of an automobile engine, for example, Patent Document 1 discloses a control device for an internal combustion engine having an electronic throttle system in accordance with a target throttle opening in order to ensure retreat travel performance when the throttle is abnormal. It describes changing the number of cylinders (the number of cylinders to be cut) for fuel cut to adjust the output and restricting the number of cylinders to a predetermined value according to the ON operation of the brake switch.
Patent Document 2 discloses the number of cylinders that perform fuel cut according to the deviation of the engine speed from a predetermined speed in order to respond to the driver's deceleration request even when the throttle valve is stuck open. It is described to set.
Patent Document 3 describes that the number of cylinders at which fuel injection is stopped is changed in accordance with the accelerator opening during the retreat travel in order to enable stable retreat travel even if a throttle valve open failure occurs. ing.

JP 2000-320380 A JP-A-11-148407 JP-A-11-166439

In general, in gasoline engines, CO, NOx, and HC in exhaust gas are purified by a three-way catalyst in which a noble metal such as platinum, rhodium, and palladium is supported on a ceramic carrier.
In such a three-way catalyst, the amount of air passing through the execution of the fuel cut control increases, and the NOx purification performance deteriorates when the inside becomes an oxygen-excess state (oxidizing atmosphere).
When the fuel cut is completed and the fuel injection is resumed, the amount of oxygen in the three-way catalyst gradually decreases and the catalyst becomes neutral, but in order to improve the exhaust gas purification performance immediately after the restart of the injection, the catalyst There is a demand for shortening the time required for neutralization.
In view of the problems described above, an object of the present invention is to provide an engine control device that improves exhaust gas purification performance while suppressing fuel consumption during deceleration.

The present invention solves the above-described problems by the following means.
The invention according to claim 1 is an engine control device that controls an engine having a plurality of injectors that are respectively provided in a plurality of cylinders and inject fuel in accordance with an injection signal into a combustion chamber or an intake port. A fuel injection control unit that performs fuel injection by giving the injection signal, and a fuel cut condition determination unit that determines whether a fuel cut condition is executed in which fuel cut control for stopping fuel injection of the injector is performed in at least one cylinder And a deceleration detection unit that detects deceleration of a vehicle on which the engine is mounted, and the fuel injection control unit detects the fuel when the fuel cut condition determination unit determines that the fuel cut condition is satisfied. Cut control is performed, and the number of cylinders at which the fuel injection is stopped is increased in accordance with an increase in the deceleration. An engine control unit for.
According to this, in the case of slow deceleration with a relatively small deceleration, the number of cylinders that perform fuel cut is reduced, and fuel injection is continued in some cylinders, thereby reducing the amount of oxygen supplied to the catalyst. In addition, it is possible to reduce the time required for the neutralization of the catalyst at the end of the fuel cut by suppressing the inside of the catalyst layer from becoming an oxidizing atmosphere, and to improve the exhaust gas purification performance at the time of reacceleration (at the time of restarting fuel injection).
Even in this case, the fuel consumption can be suppressed by cutting the fuel in some cylinders.
On the other hand, in the case of rapid deceleration with a relatively large deceleration, the number of cylinders that perform fuel cut can be increased to reduce engine output and improve drivability (ease of driving).

The invention according to claim 2 is provided with an output shaft speed sensor that detects an output shaft rotation speed of the engine, and the fuel injection control unit changes the output shaft rotation speed by a predetermined amount or more during execution of the fuel cut control. 2. The engine control device according to claim 1, wherein the number of cylinders in which the fuel injection is stopped is reduced when the fuel injection occurs.
According to this, when the rotational speed fluctuation of the output shaft is deteriorated due to the fuel cut of some cylinders, the rotational speed fluctuation is suppressed by reducing the number of cylinders that perform the fuel cut, and the occurrence of the vehicle body vibration or the like is suppressed. Can be prevented.

  As described above, according to the present invention, it is possible to provide an engine control device that improves exhaust gas purification performance during reacceleration while suppressing fuel consumption during deceleration.

It is a block diagram which shows the structure of embodiment of the engine control apparatus to which this invention is applied. It is a flowchart which shows the operation | movement at the time of the fuel cut in the engine control apparatus of embodiment.

Hereinafter, an embodiment of an engine control device to which the present invention is applied will be described.
The engine control apparatus according to the embodiment is provided, for example, in a gasoline engine for automobiles, and controls the engine and its auxiliary devices in an integrated manner.

FIG. 1 is a block diagram schematically showing the configuration of the engine control apparatus of the embodiment.
The engine 1 is a four-stroke horizontally opposed four-cylinder direct-injection (in-cylinder injection) gasoline engine mounted as a driving power source in an automobile such as a passenger car.
The output of the engine 1 is a drive (not shown) having a transmission such as a continuously variable transmission (CVT) (not shown) having a variator, a torque converter, etc., and an AWD transfer, a propeller shaft, a final reduction gear, a differential, a drive shaft, etc. It is transmitted to the drive wheels of the vehicle via a force transmission mechanism.

The engine 1 includes a first cylinder 10, a second cylinder 20, and a third cylinder arranged in sequence from the front end side of the crankshaft (not shown) that is the output shaft (the opposite side to the transmission and the front side when mounted vertically). 30 and a fourth cylinder 40.
In the engine 1, for example, the crankshaft is vertically arranged substantially along the longitudinal direction of the vehicle.
The first cylinder 10 and the third cylinder 30 are provided in the right bank arranged on the right side in the vehicle width direction, and the second cylinder 20 and the fourth cylinder 40 are provided in the left bank arranged on the left side in the vehicle width direction.

The first cylinder 10 and the second cylinder 20, and the third cylinder 30 and the fourth cylinder 40 are arranged so as to face each other substantially across the crankshaft in a state shifted by the offset amount of the crankpin of each cylinder. .
The ignition sequence (explosion sequence) in the engine 1 is set in the order of the first cylinder 10, the third cylinder 30, the second cylinder 20, and the fourth cylinder 40, and is ignited at substantially equal intervals every 180 ° in crank angle ( Explosion).

The first cylinder 10, the second cylinder 20, the third cylinder 30, and the fourth cylinder 40 are respectively a cylinder, a piston, a combustion chamber, an intake / exhaust port, an intake / exhaust valve, a valve drive mechanism, and the like. 31, 41, spark plugs 12, 22, 32, 42 and the like.
The injectors 11, 21, 31, and 41 are injection devices that inject atomized gasoline directly into the combustion chamber of each cylinder.
The fuel injection amounts and fuel injection timings of the injectors 11, 21, 31, 41 are controlled by the ECU 100 according to the operating state of the engine 1.
Injectors 11, 21, 31, and 41 are introduced and accumulated with fuel pressurized by a fuel pump (not shown), and open according to an injection signal given from ECU 100 to inject fuel.

The spark plugs 12, 22, 32, 42 ignite the air-fuel mixture formed in each cylinder by electrical spark.
The ignition timing of the spark plugs 12, 22, 32, 42 is controlled by the ECU 100.

The engine 1 includes an intake device 50, an exhaust device 60, a valve timing variable device (not shown), a cooling device, a lubrication device, an EGR device, and the like.
The intake device 50 introduces combustion air into each cylinder.
The intake device 50 includes an intake duct (not shown) that introduces outside air (atmosphere) as combustion air, an air cleaner (not shown) that filters foreign matter such as dust, a throttle valve 51 that controls the air flow rate for adjusting the output of the engine 1, and a throttle valve An intake manifold 52 and the like for introducing the air that has passed through 51 into the intake port of each cylinder are provided.
The throttle valve 51 is an electric throttle having a butterfly valve (throttle valve) that is opened and closed by an electric actuator, and the opening degree is controlled by the ECU 100 in accordance with a required torque set according to the accelerator operation of the driver.

The exhaust device 60 discharges exhaust gas (burned gas) discharged from the combustion chamber of each cylinder 10, 20, 30, 40 via the exhaust port.
The exhaust device 60 includes an exhaust manifold 61, an exhaust pipe 62, a catalytic converter 63, a silencer 64, an air-fuel ratio sensor 65, a rear O ₂ sensor 66, and the like.

The exhaust manifold 61 is a collecting pipe that collects exhaust gas discharged from the exhaust ports of the cylinders 10, 20, 30, and 40.
The exhaust pipe 62 is a pipe line that discharges the exhaust gas gathered in the exhaust manifold 61 to the outside.

The catalytic converter 63 is an exhaust gas aftertreatment device provided at an intermediate portion of the exhaust pipe 62.
The catalytic converter 63 is a three-way catalyst in which a noble metal such as platinum, rhodium or palladium is supported on a carrier such as alumina.
Catalytic converter 63 is in a predetermined active region in which the air-fuel ratio of the engine 1 is near stoichiometric, it has a function of reducing HC in exhaust gas, CO, and NO _X.

  The silencer 64 is a silencer that is provided downstream of the catalytic converter 63 (exit side) in the exhaust pipe 62 and reduces acoustic energy.

The air-fuel ratio sensor 65 is provided in the vicinity of the inlet of the catalytic converter 63 and generates different output voltages depending on the air-fuel ratio in the engine 1.
The ECU 100 performs air-fuel ratio feedback control for setting the fuel injection amount so that the air-fuel ratio in the engine 1 falls within the active range of the three-way catalyst according to the output of the air-fuel ratio sensor 65.

The rear O ₂ sensor 66 is provided in the vicinity of the outlet of the catalytic converter 63 and generates different output voltages depending on the O ₂ concentration in the exhaust gas.
The output of the rear O ₂ sensor 66 is transmitted to the ECU 100.

The engine 1 further includes a crank angle sensor 70, a water temperature sensor 80, and the like.
The crank angle sensor 70 detects an angular position of a crankshaft (not shown) that is an output shaft of the engine 1.
The crank angle sensor 70 includes a sensor plate 71, a position sensor 72, and the like.
The sensor plate 71 is a disc-like member fixed to the front end portion of the crankshaft, and has a sprocket-like shape formed by radially projecting a plurality of vanes (teeth) at predetermined angular intervals on the outer peripheral edge portion. It has become.
The position sensor 72 is a magnetic pickup disposed to face the outer peripheral edge of the sensor plate 71, and includes a magnet, a core, a coil, a terminal, and the like.
The position sensor 72 outputs a predetermined pulse signal when the vane of the sensor plate 71 passes immediately before.
The ECU 100 can calculate the rotational speed (crankshaft rotational speed) of the engine 1 based on the output of the crank angle sensor 70.

The water temperature sensor 80 detects the temperature of cooling water (coolant) flowing through a water jacket that is a cooling water flow path formed in the cylinder head and the cylinder.
Outputs of the crank angle sensor 70 and the water temperature sensor 80 are transmitted to the ECU 100.

The engine control unit (ECU) 100 controls the engine 1 and its auxiliary devices in an integrated manner.
The ECU 100 includes, for example, an information processing device such as a CPU, a storage device such as a RAM and a ROM, an input / output interface, a bus connecting these, and the like.
The ECU 100, for example, according to a required torque set based on a driver's accelerator operation or the like, an opening of a throttle valve (not shown), a fuel injection amount, a fuel injection timing, so that an actual torque substantially matches the required torque, Controls ignition timing, valve timing, etc.

The ECU 100 constitutes a main part of the engine control device according to the present invention, and also has a function as a fuel injection control unit.
The ECU 100 constitutes a cylinder independent fuel injection system capable of individually controlling the presence / absence of fuel injection, the injection amount, the injection timing and the like for each cylinder.
The ECU 100 receives an output value of an accelerator pedal sensor 110 that detects an operation amount (depression stroke) of an accelerator pedal by a driver, and the ECU 100 sets a required torque based on the output value.

  Further, the vehicle speed sensor 120, the front / rear G sensor 130, and the brake switch 140 are connected to the ECU 100 directly or indirectly through another unit, an in-vehicle LAN system, or the like, and the output values thereof can be acquired.

The vehicle speed sensor 120 detects the rotational speed of the vehicle wheel.
The vehicle speed sensor 120 is provided, for example, in a wheel hub portion, and generates a vehicle speed pulse signal having a frequency substantially proportional to the rotational speed of the wheel.
The ECU 100 can calculate the traveling speed (vehicle speed) of the vehicle based on the acquired vehicle speed pulse signal.

  The front-rear G sensor 130 includes an acceleration pickup configured by, for example, MEMS technology, and detects acceleration acting in the front-rear direction of the vehicle body.

The brake switch 140 is a switch that is turned on in response to a brake pedal operation by the driver.
The brake switch 140 functions as a deceleration detection unit according to the present invention in cooperation with the front / rear G sensor 130.

The ECU 100 executes a fuel cut that stops fuel injection from the injectors 11, 21, 31, 41 when a preset fuel cut condition is satisfied, mainly for the purpose of improving the fuel efficiency of the vehicle.
As the fuel cut condition, for example, the vehicle speed and the engine speed are each equal to or higher than a predetermined threshold, and the driver request torque is substantially 0 (accelerator off).
The ECU 100 also functions as a fuel cut condition determining unit according to the present invention.

In the present embodiment, in order to suppress oxygen supply to the catalytic converter 63 at the time of fuel cut, control is performed to change the number of cylinders that perform fuel cut (the number of cylinders that stop fuel injection) according to the deceleration. Is going.
FIG. 2 is a flowchart showing an operation at the time of fuel cut in the engine control apparatus of the embodiment.
Hereinafter, the steps will be described step by step.

<Step S01: Satisfaction of fuel cut condition>
The ECU 100 determines whether or not the current operating state of the engine 1 satisfies a preset fuel cut condition.
As the fuel cut condition, for example, the driver request torque set based on the output of the accelerator pedal sensor 110 is a predetermined value or less (for example, substantially 0), the vehicle speed and the engine speed are within a predetermined range, etc. There is.
When the fuel cut condition is satisfied, the process proceeds to step S02. When the fuel cut condition is not satisfied, the series of processes is ended (returned), and normal fuel injection control is continued.

<Step S02: Brake switch on / off determination>
The ECU 100 determines whether the brake switch 140 is on or off.
When the brake switch 140 is on, the process proceeds to step S03, and when it is off, the process proceeds to step S05.

<Step S03: Deceleration Determination (1)>
The ECU 100 compares the deceleration of the vehicle body detected by the longitudinal G sensor 130 with a preset threshold value T1.
If the deceleration is greater than or equal to the threshold value T1, the process proceeds to step S04. If the deceleration is less than the threshold value T1, the process proceeds to step S06.

<Step S04: Deceleration Determination (2)>
The ECU 100 compares the deceleration of the vehicle body detected by the front / rear G sensor 130 with a preset threshold value T2 (T2> T1).
When the deceleration is greater than or equal to the threshold value T2, the process proceeds to step S08, and when it is less than the threshold value T2, the process proceeds to step S07.

<Step S05: Execution of 1-cylinder fuel cut>
The ECU 100 executes fuel cut in one cylinder (stops fuel injection) and continues fuel injection in the other three cylinders.
Thereafter, the process proceeds to step S09.

<Step S06: 2-Cylinder Fuel Cut Execution>
The ECU 100 executes fuel cut in the two cylinders and continues fuel injection in the other two cylinders.
Thereafter, the process proceeds to step S09.

<Step S07: 3-cylinder fuel cut execution>
The ECU 100 executes fuel cut in the three cylinders and continues fuel injection in the remaining one cylinder.
Thereafter, the process proceeds to step S09.

<Step S08: 4-cylinder fuel cut execution>
The ECU 100 performs fuel cut in all four cylinders.
Thereafter, the process proceeds to step S09.

<Step S09: Judgment of engine rotation fluctuation>
Based on the output of the crank angle sensor 70, the ECU 100 detects crankshaft rotation fluctuations resulting from the execution of fuel cut control.
For example, if a periodic rotational speed fluctuation (vibration) having an amplitude equal to or greater than a preset threshold value has occurred, the process proceeds to step S10, and in other cases, a series of processing ends (returns).

<Step S10: Fuel cut cylinder reduction>
The ECU 100 restarts fuel injection in at least one of the cylinders that are performing the fuel cut, reduces the number of cylinders that are performing the fuel cut, and suppresses fluctuations in the rotational speed of the crankshaft.
Thereafter, the series of processing is terminated (returned).

In the above-described processing, when fuel cut (stop of fuel injection) is performed in a plurality of cylinders, the fuel cut may be started simultaneously in all cylinders that perform fuel cut. In order to suppress this, the timing for starting the fuel cut may be shifted for each cylinder (a delay is provided).
Further, even when the fuel cut condition is not satisfied and the normal fuel injection control is resumed, the timing for ending the fuel cut (timing for restarting the fuel injection) may be shifted for each cylinder.

According to this embodiment described above, the following effects can be obtained.
(1) The deceleration of the vehicle body is detected based on the on / off state of the brake switch 140 and the output of the front / rear G sensor 130. In the case of slow deceleration, the number of cylinders that perform fuel cut is reduced, and fuel injection is performed in some cylinders. By reducing the amount of oxygen supplied to the catalytic converter 63, suppressing the inside of the catalyst layer from becoming an oxidizing atmosphere, reducing the time required to neutralize the catalyst at the end of the fuel cut, and at the time of reacceleration The exhaust gas purification performance can be improved.
Further, by performing fuel cut in some cylinders, an effect of suppressing fuel consumption can be obtained.
On the other hand, in the case of rapid deceleration, the number of cylinders that perform fuel cut can be increased to improve drivability.
(2) When the rotational speed fluctuation of the crankshaft is deteriorated due to the fuel cut of some cylinders, the rotational speed fluctuation is suppressed by reducing the number of cylinders that perform the fuel cut and the occurrence of vehicle body vibration is prevented. Can do.

(Modification)
The present invention is not limited to the embodiments described above, and various modifications and changes are possible, and these are also within the technical scope of the present invention.
(1) The configuration of the engine control device and the engine to be controlled can be appropriately changed without being limited to the configuration of the above-described embodiment.
For example, in the embodiment, the engine is a direct injection (in-cylinder injection) horizontally opposed four-cylinder gasoline engine, but the cylinder layout and the number of cylinders can be changed as appropriate.
The present invention can also be applied to an engine that uses port injection or port injection and direct injection in combination.
(2) In the embodiment, the deceleration is detected using the front-rear G sensor, but the present invention is not limited to this and may be detected by other methods.
For example, the deceleration may be detected based on the depression force, stroke or wheel cylinder hydraulic pressure of the brake pedal in the brake device.
Further, the deceleration may be calculated by differentiating the vehicle speed.

DESCRIPTION OF SYMBOLS 1 Engine 10 1st cylinder 11 Injector 12 Spark plug 20 2nd cylinder 21 Injector 22 Spark plug 30 3rd cylinder 31 Injector 32 Spark plug 40 4th cylinder 41 Injector 42 Spark plug 50 Intake device 51 Throttle valve 52 Intake manifold 60 Exhaust device 61 Exhaust Manifold 62 Exhaust Pipe 63 Catalytic Converter 64 Silencer 65 Air-fuel Ratio Sensor 66 Rear O ₂ Sensor 70 Crank Angle Sensor 71 Sensor Plate 72 Position Sensor 80 Water Temperature Sensor 100 Engine Control Unit (ECU)
110 Accelerator pedal sensor 120 Vehicle speed sensor 130 Front / rear G sensor 140 Brake switch

Claims (2)

An engine control device that controls an engine having a plurality of injectors that are respectively provided in a plurality of cylinders and inject fuel in accordance with an injection signal into a combustion chamber or an intake port,
A fuel injection control section for giving the injector an injection signal to perform fuel injection;
A fuel cut condition discriminating unit that discriminates satisfaction of a fuel cut condition in which fuel cut control for stopping fuel injection of the injector is performed in at least one cylinder;
A deceleration detecting unit for detecting deceleration of a vehicle on which the engine is mounted,
The fuel injection control unit performs the fuel cut control when the fuel cut condition determination unit determines that the fuel cut condition is satisfied, and the cylinder in which the fuel injection is stopped in response to an increase in the deceleration An engine control device characterized by increasing the number. An output shaft speed sensor for detecting the output shaft rotation speed of the engine;
The fuel injection control unit reduces the number of cylinders in which the fuel injection is stopped when the output shaft rotation speed fluctuates more than a predetermined value during execution of the fuel cut control. The engine control apparatus according to claim 1.

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