JP2017101582A - Engine control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine control device capable of restricting discharging of white smoke or unburnt gas after completion of fuel cut control.SOLUTION: This invention comprises a motion number calculation part 32 for measuring a piston motion number that is the number of times of vertical motion of a piston of an engine 2 during a fuel cut controlling operation; an in-cylinder temperature estimating part 33 for estimating in-cylinder temperature of the engine 2 for every specified time and calculating a completion time in-cylinder temperature estimated value Tend on the basis of a start time in-cylinder temperature estimated value Tstart, an intake temperature of the engine 2 at the starting time of fuel cut control and the piston number of motions; and a white smoke prevention control part 35 for calculating an amount of correction for correcting engine control amount including a fuel injection amount, a fuel injection timing and a throttle opening degree on the basis of the completion time in-cylinder temperature estimated value Tend and controlling the engine 2 with the engine control amount corrected by the amount of correction ranging from post-completion of fuel cut control to Z-times of fuel injection.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an engine control device.

  In a vehicle equipped with an engine, when the foot is released from the accelerator pedal while traveling or downhill, fuel cut control is executed to stop fuel injection in order to improve fuel consumption and engine brake. When the fuel cut control is executed, the intake air passes through the engine cylinder in an unburned state, and the temperature in the cylinder rapidly decreases.

  At this time, in an engine that does not measure the temperature in the cylinder of the engine, even when the temperature in the engine cylinder is reduced at the time of fuel re-injection after the end of fuel cut control, the injection amount or injection corresponding to the temperature in the cylinder The timing cannot be controlled, the combustion state deteriorates, and a large amount of white smoke or unburned gas is discharged.

  Patent Document 1 describes that the time from the start of fuel cut to the re-injection of fuel is measured and the fuel injection timing is corrected according to this measurement time.

JP-A-9-209799

  However, in such an engine control device, since the fuel injection timing is corrected only by the time during which the fuel cut control is performed, the accuracy of the estimated temperature drop in the cylinder is low, and during the fuel cut Depending on the engine temperature state, the effect of suppressing the emission of white smoke and unburned gas may be reduced.

  Then, this invention aims at providing the engine control apparatus which can suppress discharge | emission of the white smoke and unburned gas after completion | finish of fuel cut control.

  One aspect of the invention of an engine control apparatus that solves the above problems is an engine control apparatus having a fuel cut control unit that executes fuel cut control for stopping fuel injection to the engine when a preset condition is satisfied. A number-of-movements calculation unit for measuring the number of piston movements, which is the number of times the piston of the engine that is performing the fuel cut control is moved up and down, and estimating an in-cylinder temperature of the engine every predetermined time, In-cylinder temperature for estimating the in-cylinder temperature at the end of the fuel cut control based on the estimated value of the in-cylinder temperature at the start of control, the intake air temperature of the engine at the start of the fuel cut control, and the number of piston movements A correction amount for correcting an engine control amount including a temperature estimation unit, at least a fuel injection amount, a fuel injection timing, and a throttle opening, A white value for controlling the engine with the engine control amount calculated based on the estimated value of the in-cylinder temperature at the end of the fuel cut control and corrected with the correction amount until a predetermined period elapses after the fuel cut control ends. A smoke prevention control unit.

  Thus, according to one aspect of the present invention, it is possible to suppress the emission of white smoke and unburned gas after the end of fuel cut control.

FIG. 1 is a block diagram showing an engine control apparatus according to an embodiment of the present invention. FIG. 2 is a diagram showing an engine control apparatus according to an embodiment of the present invention, and is a graph showing an example of a map for calculating an estimated end-of-cylinder temperature. FIG. 3 is a diagram showing an engine control apparatus according to an embodiment of the present invention, and is a block diagram showing a process of calculating an estimated end-of-cylinder temperature. FIG. 4 is a diagram showing an engine control apparatus according to an embodiment of the present invention, and is a flowchart showing the white smoke prevention control processing procedure.

  Hereinafter, an engine control apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings.

  In FIG. 1, a vehicle 1 equipped with an engine control apparatus according to an embodiment of the present invention includes an engine 2 as an internal combustion engine and an ECU (Electronic Control Unit) 3 as a control unit.

  The engine 2 is constituted by a four-cycle diesel engine that performs a series of four strokes including an intake stroke, a compression stroke, an expansion stroke, and an exhaust stroke while the piston reciprocates twice through the cylinder.

  The engine 2 includes a fuel supply device (not shown). The fuel supply device has an injector 21 corresponding to each cylinder. The engine 2 is not limited to a diesel engine, and may be a premixed compression ignition type gasoline engine capable of HCCI (Homogeneous Charge Compression Ignition) combustion, for example.

  The injector 21 is connected to the ECU 3, and the fuel injection timing and the fuel injection amount are controlled by the ECU 3.

  The cylinder of the engine 2 is provided with a glow plug 22 that raises the temperature in the cylinder. The glow plug 22 is connected to the ECU 3, and in response to a glow plug operation request from the ECU 3, for example, the glow plug 22 becomes red hot when an electric current is passed immediately before the engine 2 is started, and a part of the fuel spray is blown on the ignition.・ It functions as a starting aid that promotes combustion.

  The engine 2 has an intake passage (not shown) for taking outside air into the cylinder. A supercharger 23 and a throttle valve 24 are provided in the intake passage.

  The supercharger 23 is configured by a turbocharger having a turbine (not shown) provided in an exhaust passage (not shown) of the engine 2 and a compressor (not shown) that rotates integrally with the turbine.

  The turbine is driven to rotate by exhaust of the engine 2. The compressor is driven to rotate integrally with the turbine, thereby compressing the outside air and feeding the compressed outside air into the intake passage.

  The supercharger 23 is provided with a movable vane (not shown) that can adjust the flow rate of the exhaust gas to the turbine. The movable vane can control the supercharging pressure that is the pressure of the intake air obtained by supercharging of the supercharger 23 by adjusting the flow rate of the exhaust gas to the turbine. The movable vane controls the supercharging pressure by changing the opening degree of the movable vane in response to the movable vane opening degree request from the ECU 3.

  The throttle valve 24 is configured to adjust the intake air amount of the engine 2 by controlling the throttle opening in accordance with the intake throttle opening request from the ECU 3.

  The engine 2 is provided with an exhaust gas recirculation pipe (not shown) that connects the intake passage and the exhaust passage. The exhaust gas recirculation pipe performs EGR (Exhaust Gas Recirculation) to recirculate a part of the exhaust gas to the intake side. The exhaust gas recirculation pipe is provided with an EGR valve 25 that opens and closes the exhaust gas recirculation pipe between fully open and fully closed. The EGR valve 25 is electrically connected to the ECU 3. The EGR valve 25 is configured to adjust the amount of exhaust gas recirculated to the intake side by controlling the valve opening according to the EGR valve opening request from the ECU 3.

  The ECU 3 includes a computer unit that includes a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), a flash memory, an input port, and an output port.

  The ROM of the computer unit stores a program for causing the computer unit to function as the ECU 3 along with various control constants and various maps. That is, the computer unit functions as the ECU 3 when the CPU executes a program stored in the ROM.

  Various sensors such as a crank position sensor 26, a water temperature sensor 27, an intake air temperature sensor 28, an accelerator opening sensor 29, and an outside air temperature sensor 30 are connected to the input port of the ECU 3.

  The crank position sensor 26 detects a rotation position (rotation angle) of a crankshaft (not shown) of the engine 2. The ECU 3 can calculate the engine speed from the detection result of the crank position sensor 26.

  The water temperature sensor 27 detects the cooling water temperature that is the temperature of the cooling water of the engine 2. The intake air temperature sensor 28 detects the temperature of air flowing through the intake passage of the engine 2. The accelerator opening sensor 29 detects an accelerator opening representing an operation amount of an accelerator pedal (not shown). The outside air temperature sensor 30 detects the temperature of outside air.

  On the other hand, various control objects such as an injector 21, a glow plug 22, a supercharger 23, a throttle valve 24, and an EGR valve 25 are connected to the output port of the ECU 3.

  For example, the ECU 3 drives the engine 2 by igniting the fuel by injecting the fuel into the injector 21 when the stroke of the engine 2 shifts from the compression stroke to the expansion stroke.

  In this embodiment, the ECU 3 performs fuel cut control for automatically stopping fuel injection of the engine 2 when the foot is released from the accelerator pedal and the engine speed is a predetermined value.

  The ECU 3 estimates the temperature in the cylinder when the fuel cut control is completed, and corrects the control of the engine 2 based on the estimated temperature.

  The ECU 3 includes an engine speed calculation unit 31, an exercise frequency calculation unit 32, an in-cylinder temperature estimation unit 33, a fuel cut control unit 34, and a white smoke prevention control unit 35.

  The engine speed calculator 31 calculates the engine speed from the detection result of the crank position sensor 26.

  The number-of-movements calculation unit 32 calculates the number of piston movements, which is the number of times the piston in the cylinder of the engine 2 has moved up and down during the fuel cut control from the detection result of the crank position sensor 26. Instead of the crank position sensor 26, a sensor for individually detecting the number of piston movements may be provided.

  The in-cylinder temperature estimation unit 33 estimates the temperature in the cylinder when the fuel cut control is finished. The in-cylinder temperature estimation unit 33 calculates the temperature in the cylinder of the engine 2 as the in-cylinder temperature estimated value Ts at a preset time interval.

  The in-cylinder temperature estimation unit 33 calculates an estimated in-cylinder temperature Ts based on the intake air temperature, the outside air temperature, the accelerator opening, the engine speed, and the EGR valve opening. The in-cylinder temperature estimation unit 33 calculates the in-cylinder temperature estimated value Ts based on a map in which the in-cylinder temperature is determined from, for example, the intake air temperature, the outside air temperature, the accelerator opening, the engine speed, and the EGR valve opening.

  As the EGR valve opening, the value of the EGR valve opening request calculated by the ECU 3 is used. A sensor may be provided in the EGR valve 25 to detect the EGR valve opening.

  The EGR valve opening is not necessary for calculating the in-cylinder temperature estimated value Ts if the intake air temperature sensor 28 can detect the temperature of the gas that is sent to the intake side by EGR and mixed with the intake air. That is, the amount of gas sent to the intake side is detected from the EGR valve opening, and the temperature of the air sucked into the cylinder is estimated from that amount.

  The in-cylinder temperature estimation unit 33 stores the in-cylinder temperature at the start of fuel cut as the start-in-cylinder temperature estimated value Tstart.

  The in-cylinder temperature estimation unit 33 stores, for example, an estimated in-cylinder temperature value Ta obtained by averaging estimated values of the in-cylinder temperature for N seconds from the start of fuel cut to N seconds before as the estimated in-cylinder temperature Tstart. To do.

  The cylinder temperature estimation unit 33 is a cylinder at the end of the fuel cut from the estimated cylinder temperature at the start Tstart, the intake air temperature at the start of the fuel cut, and the number of piston movements during the fuel cut control calculated by the number-of-motions calculation unit 32. Estimate the internal temperature.

  The in-cylinder temperature estimation unit 33 is, for example, a cylinder at the end of the fuel cut based on a map in which the in-cylinder temperature is determined from the estimated in-cylinder temperature Tstart at the start, the intake air temperature at the start of the fuel cut, and the number of piston movements during the fuel cut. An end-point cylinder internal temperature estimated value Tend, which is the internal temperature, is calculated.

  The in-cylinder temperature estimation unit 33 calculates the in-cylinder temperature estimation value Tend at the end, for example, using a map as shown in FIG. As shown in FIG. 2, for each intake air temperature at the start of fuel cut, how the temperature in the cylinder is lowered is determined by experiment or the like based on the number of piston movements.

  In FIG. 2, the in-cylinder temperature estimation unit 33 selects, for example, a graph in which the cylinder temperature at which the number of piston movements is zero is closest to the starting cylinder temperature estimation value Tstart, and the graph and the number of piston movements during fuel cut. From this, an estimated cylinder temperature at the end Tend is calculated.

  FIG. 3 is a diagram showing a process of calculating the end-of-cylinder temperature estimation value Tend. In step S1, the in-cylinder temperature estimation unit 33 calculates an estimated in-cylinder temperature Ts based on the intake air temperature, the accelerator opening, the engine speed, the outside air temperature, and the EGR valve opening.

  In step S2, the in-cylinder temperature estimation unit 33 calculates an estimated in-cylinder temperature value Ta by averaging the estimated in-cylinder temperature Ts for N seconds from the current time to N seconds before.

  In step S3, the cylinder temperature estimation unit 33 sets the cylinder temperature estimation average value Ta at the start of fuel cut control as the start cylinder temperature estimation value Tstart.

  In step S4, the number-of-movements calculation unit 32 calculates the number of piston movements from the start of fuel cut control.

  In step S5, when the fuel cut control is completed, the in-cylinder temperature estimation unit 33 starts the estimated in-cylinder temperature Tstart, the intake air temperature at the start of the fuel cut, and during the fuel cut calculated by the number-of-motions calculation unit 32. An end-of-cylinder temperature estimation value Tend is calculated from the number of piston movements.

  The fuel cut control unit 34 performs fuel cut control for automatically stopping fuel injection of the engine 2 when the foot is released from the accelerator pedal and the engine speed is a predetermined value.

  The fuel cut control unit 34 automatically stops fuel injection of the engine 2 on condition that all predetermined fuel cut requirements such as, for example, the accelerator opening is zero and the engine speed is equal to or higher than the predetermined engine speed are satisfied. .

  The white smoke prevention control unit 35 calculates a correction amount of the engine control amount based on the end-of-cylinder temperature estimation value Tend calculated by the cylinder temperature estimation unit 33 so as to suppress discharge of white smoke and unburned gas. To do. The engine control amount is a control amount such as a fuel injection amount, a fuel injection timing, a throttle opening, an EGR valve opening, a glow plug operation timing, a movable vane opening.

  The engine control amount may be corrected at least for the fuel injection amount, the fuel injection timing, and the throttle opening.

  For example, the white smoke prevention control unit 35 calculates the correction amount of each engine control amount based on a map in which the correction amount is determined by the estimated cylinder temperature at the end Tend.

  The white smoke prevention control unit 35 controls the engine 2 with the corrected engine control amount until fuel injection is performed a preset number of times Z [times] after the fuel cut control is completed. You may make it perform the engine control correct | amended only for the preset time instead of the frequency | count of fuel injection.

  The estimation of the in-cylinder temperature at the end of the fuel cut control and the correction of the engine control amount may not be performed when the engine 2 is not in the warm-up state. For example, the ECU 3 may not perform the operation when the temperature of the engine coolant detected by the water temperature sensor 27 is lower than a predetermined temperature WT [° C.].

  When the engine 2 is in a warm-up state, the temperature around the engine 2 is normally stable, so that the estimation accuracy of the in-cylinder temperature is high. On the contrary, if the engine 2 is not warmed up, the temperature around the engine 2 is not stable, and the estimation accuracy of the in-cylinder temperature is poor.

  The estimation of the in-cylinder temperature at the end of the fuel cut control and the correction of the engine control amount may not be performed when the glow plug 22 is operating. When the glow plug 22 is operating, the in-cylinder temperature does not decrease, so that the engine control amount need not be corrected.

  The operation state of the glow plug 22 is determined by a glow plug operation request from the ECU 3. A sensor may be provided in the glow plug 22 to detect the operating state.

  The white smoke prevention control process by the engine control apparatus according to the present embodiment configured as described above will be described with reference to FIG. Note that the white smoke prevention control process described below is started when the ECU 3 starts operation and is executed at a preset time interval.

  In step S11, the ECU 3 determines whether or not the engine cooling water temperature detected by the water temperature sensor 27 is equal to or higher than a predetermined temperature WT [° C.]. If it is determined that the temperature of the engine coolant is not WT or higher, the ECU 3 returns to step S11 and repeats the process.

  If it is determined that the temperature of the engine cooling water is equal to or higher than WT, in step S12, the ECU 3 determines whether fuel cut control is being executed. If it is determined that the fuel cut control is not being executed, the ECU 3 returns to step S11 and repeats the process.

  When it is determined that the fuel cut control is being performed, in step S13, the ECU 3 determines whether or not the glow plug 22 is off. If it is determined that the glow plug 22 is not off, the ECU 3 returns to step S11 and repeats the process.

  When it is determined that the glow plug 22 is off, in step S14, the ECU 3 estimates the in-cylinder temperature estimated average value Ta by averaging the in-cylinder temperature estimated value Ts for N seconds before the start of fuel cut control. Let it be the value Tstart.

  In step S15, the ECU 3 starts counting the number of piston movements during execution of the fuel cut control.

  In step S16, the ECU 3 determines whether or not the fuel cut control is finished. If it is determined that the fuel cut control has not ended, the ECU 3 repeats the process of step S16.

  When it is determined that the fuel cut control has ended, in step S17, the ECU 3 ends the count of the number of piston movements during execution of the fuel cut control.

  In step S18, the ECU 3 calculates an end-in-cylinder temperature estimated value Tend from the start-in-cylinder temperature estimated value Tstart, the number of piston movements during fuel cut control, and the intake air temperature at the start of fuel cut.

  In step S19, the ECU 3 calculates an engine control correction amount from the estimated cylinder temperature at the end Tend.

  In step S20, the ECU 3 executes the white smoke prevention control by correcting the engine control amount by the engine control correction amount and controlling the engine.

  In step S21, the ECU 3 determines whether or not fuel injection is performed Z times after the fuel cut control is completed. When it is determined that the Z-time fuel injection has not been executed, the ECU 3 repeats the process of step S21.

  When it is determined that the Z-time fuel injection has been executed, in step S22, the ECU 3 ends the white smoke prevention control by ending the correction of the engine control amount by the engine control correction amount, and ends the process.

  Thus, in the above-described embodiment, the number-of-movements calculation unit 32 that measures the number of piston movements, which is the number of times the piston of the engine 2 that is performing fuel cut control is moved up and down, In-cylinder temperature estimation that estimates the temperature and calculates an estimated end-of-cylinder temperature Tend based on the estimated in-cylinder temperature Tstart, the intake air temperature of the engine 2 at the start of fuel cut control, and the number of piston movements The correction amount for correcting the engine control amount including the portion 33, the fuel injection amount, the fuel injection timing, and the throttle opening is calculated based on the estimated cylinder temperature at the end Tend, and after the fuel cut control is completed A white smoke prevention control unit 35 for controlling the engine 2 with the engine control amount corrected by the correction amount until the Z-time fuel injection is executed.

  Thus, the end cylinder temperature estimate Tend is calculated based on the start cylinder temperature estimate Tstart, the intake air temperature of the engine 2 at the start of fuel cut control, and the number of piston movements, and the end cylinder temperature A correction amount of the engine control amount is calculated based on the estimated value Tend, and the engine 2 is controlled by the engine control amount corrected by the correction amount. For this reason, at the time of fuel re-injection at the end of fuel cut control, combustion according to the temperature in the cylinder can be performed, the deterioration of the combustion state in the cylinder is prevented, and the emission of white smoke and unburned gas is suppressed. be able to.

  The in-cylinder temperature estimation unit 33 calculates an in-cylinder temperature estimation average value Ta by averaging the in-cylinder temperature estimation value Ts from the start of fuel cut control to N seconds before, and calculates the in-cylinder temperature estimation average value Ta. The starting cylinder temperature estimation value Tstart is assumed.

  Thus, the average value of the in-cylinder temperature estimated value Ts from the start of fuel cut control to N seconds before is set as the in-cylinder temperature estimated value Tstart at the start. For this reason, it is possible to improve the accuracy of the starting cylinder temperature estimation value Tstart while suppressing variations in the cylinder temperature estimation value Ts.

  The in-cylinder temperature estimation unit 33 calculates an in-cylinder temperature estimation value Ts based on the intake air temperature, the outside air temperature, the accelerator opening, the engine speed, and the EGR valve opening.

  Thereby, the cylinder temperature is estimated based on the intake air temperature, the outside air temperature, the accelerator opening, the engine speed, and the EGR valve opening. For this reason, the in-cylinder temperature estimated value Ts can be calculated with high accuracy.

  Further, the white smoke prevention control unit 35 does not correct the engine control amount when the glow plug 22 is operating.

  Thereby, when the glow plug 22 is operating and the temperature in the cylinder is not lowered, the white smoke prevention control is not performed. For this reason, the combustion state in a cylinder can be stabilized.

  Further, the white smoke prevention control unit 35 corrects the engine control amount until the fuel injection is performed Z times after the fuel cut control is completed.

  Thus, the engine control amount is corrected until fuel injection is performed Z times. For this reason, the engine control amount is not corrected when the temperature in the cylinder returns to the normal temperature, and the combustion state in the cylinder can be stabilized.

  While embodiments of the invention have been disclosed, it will be apparent to those skilled in the art that changes may be made without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims.

1 Vehicle 2 Engine 3 ECU
DESCRIPTION OF SYMBOLS 21 Injector 22 Glow plug 24 Throttle valve 25 EGR valve 26 Crank position sensor 28 Intake temperature sensor 31 Engine speed calculation part 32 Number of movements calculation part 33 In-cylinder temperature estimation part 34 Fuel cut control part 35 White smoke prevention control part

Claims (5)

An engine control device having a fuel cut control unit for executing fuel cut control for stopping fuel injection to the engine when a preset condition is satisfied,
A number-of-movements calculation unit that measures the number of piston movements, which is the number of times the piston of the engine that is performing the fuel cut control has moved up and down;
The cylinder temperature of the engine is estimated every predetermined time, and based on the estimated value of the cylinder temperature at the start of the fuel cut control, the intake air temperature of the engine at the start of the fuel cut control, and the number of piston movements A cylinder temperature estimation unit for estimating the cylinder temperature at the end of the fuel cut control;
A correction amount for correcting an engine control amount including at least a fuel injection amount, a fuel injection timing, and a throttle opening is calculated based on an estimated value of the in-cylinder temperature at the end of the fuel cut control, and the fuel cut An engine control device comprising: a white smoke prevention control unit that controls the engine with the engine control amount corrected by the correction amount until a predetermined period has elapsed after the end of the control.   The in-cylinder temperature estimation unit calculates an average value of estimated values of the in-cylinder temperature from the start of the fuel cut control to a predetermined period before, and estimates the average value of the in-cylinder temperature at the start of the fuel cut control. The engine control device according to claim 1, which is a value.   The engine control device according to claim 1 or 2, wherein the in-cylinder temperature estimation unit estimates an in-cylinder temperature of the engine based on an EGR valve opening.   The engine control device according to any one of claims 1 to 3, wherein the white smoke prevention control unit does not correct the engine control amount when a glow plug is operating.   5. The engine control amount correction according to claim 1, wherein the white smoke prevention control unit corrects the engine control amount until fuel injection is performed a predetermined number of times or a predetermined time has elapsed after completion of the fuel cut control. The engine control apparatus according to item 1.