JP2021001570A - Accumulation type fuel injection control device and control method of accumulation type fuel injection control device - Google Patents

Abstract

To provide an accumulation type fuel injection control device capable of calculating a proper correction amount in starting an internal combustion engine under a low temperature environment.SOLUTION: An accumulation type fuel injection control device includes: a pre-starting viscosity calculation portion for calculating the viscosity of a fuel before starting an internal combustion engine; an after-starting viscosity calculation portion for calculating the viscosity of the fuel after starting the internal combustion engine; an idling control portion for calculating a target idle injection amount to keep an idling rotation speed of the internal combustion engine at a target rotation speed; a correction idle injection amount calculation portion for calculating a corrective idle injection amount to compensate shortage of an injection amount in the target idle injection amount, a corrective idle injection amount target value calculation portion for calculating the corrective idle injection amount target value as a target value of the corrective idle injection amount; and a correction portion for correcting the corrective idle injection amount on the basis of first difference as the difference between the target idle injection amount and the corrective idle injection amount, and second difference as the difference between the target idle injection amount and the corrective idle injection amount target value.SELECTED DRAWING: Figure 7

Description

The present invention relates to fuel injection amount control of an accumulator type fuel injection control device. In particular, it relates to fuel injection amount control when starting an internal combustion engine in a low temperature environment.

Conventionally, as a device for supplying fuel to an internal combustion engine, fuel is pressurized by a high-pressure pump and pumped to a common rail which is a pressure accumulator, and the accumulated fuel is supplied to a fuel injection valve, and high pressure is applied from the fuel injection valve to the internal combustion engine. Accumulation type fuel injection control devices that inject fuel are known.

In the accumulator type fuel injection control device, when the internal combustion engine is started in a low temperature environment, the viscosity of the fuel used is grasped and various control values are corrected. In a low temperature environment, the viscosity of the fuel becomes high, so that the resistance in the moving part becomes large, and the performance of the accumulator fuel injection control device may be affected. This amendment aims to suppress this effect.

For example, when the fuel injection valve is of a type in which the back pressure on the rear end side of the nozzle needle that opens and closes the fuel injection hole is controlled by the solenoid valve, the solenoid valve is driven before the start of the internal combustion engine. The viscosity of the fuel is grasped and used for controlling the pressure of the fuel in the common rail (hereinafter referred to as "rail pressure").

Specifically, before cranking, the fuel injection valve is energized to open and close the internal solenoid valve, and the time from the time when the energization is cut off to the peak of the induced electromotive force generated in the solenoid valve after the energization is cut off. Is measured, the difference from the standard time measured in advance is calculated, and the viscosity of the fuel is calculated from the time difference.

In this method, the peak of the induced electromotive force generated when the solenoid valve is de-energized corresponds to the time when the solenoid valve is closed, and from the time when the solenoid valve is de-energized to the peak of the induced electromotive force, that is, This is an application of the fact that the time required for the valve to be completely closed depends on the viscosity of the fuel. (See, for example, Patent Document 1)

JP 2013-256888

The viscosity of the fuel may be used to control the fuel injection valve when starting an internal combustion engine in a low temperature environment. More specifically, the fuel injection valve is controlled by the energization time of the solenoid valve, which is obtained by map search or the like, based on the target injection amount and the rail pressure. When the viscosity of the fuel becomes high in a low temperature environment, the fuel injection amount decreases as compared with the normal temperature even if the energization time of the solenoid valve is the same. This is because as the viscosity of the fuel increases, the resistance of the moving portion inside the fuel injection valve increases, and as a result, the valve opening time of the injection nozzle becomes shorter. Therefore, when the internal combustion engine is started in a low temperature environment, correction is performed so that the fuel injection amount becomes appropriate by extending the energizing time of the solenoid valve as compared with the normal temperature.

The correction of the energization time is executed so that the correction amount decreases as time elapses after the start of the internal combustion engine. This is because the temperature of the fuel inside the fuel injection valve gradually rises as time passes after the start of the internal combustion engine, and the viscosity of the fuel approaches that at room temperature. Finally, the correction of the energization time based on the viscosity of the fuel becomes unnecessary.

Since the viscosity of the fuel is calculated before the start of the internal combustion engine, the correction amount of the energization time after the start of the internal combustion engine is the temperature of the cooling water of the internal combustion engine (hereinafter referred to as "cooling water temperature"). Calculated using. That is, the correction amount of the energization time after the start of the internal combustion engine is based on the viscosity of the fuel calculated before the start of the internal combustion engine and the difference between the cooling water temperature grasped at the start of the internal combustion engine and the current cooling water temperature. Calculated based on.

The above correction amount is calculated by setting in advance the relationship between the viscosity at the start of the internal combustion engine, the change in the cooling water temperature after the start of the internal combustion engine, and the required correction amount by a test or simulation. It becomes feasible.

By the way, depending on the environment in which the vehicle equipped with the internal combustion engine is used, the correlation between the rate of increase in the cooling water temperature and the rate of increase in the fuel temperature inside the fuel injection valve after the start of the internal combustion engine may deviate from the assumption. is there. The assumption here refers to the correlation between the rate of increase in the cooling water temperature and the rate of increase in the fuel temperature inside the fuel injection valve, which was grasped based on tests at the development stage. If the rate of increase in the fuel temperature inside the fuel injection valve is slower than expected with respect to the rate of increase in the cooling water temperature, the control device will overestimate the fuel temperature inside the fuel injection valve, resulting in a correction amount. Is too small. In addition, if the rate of increase in the fuel temperature inside the fuel injection valve is faster than expected with respect to the rate of increase in the cooling water temperature, the control device will underestimate the fuel temperature inside the fuel injection valve as a result. The amount of correction becomes excessive.

Such a deviation in the correction amount occurs because the cooling water temperature is used as a substitute value for the fuel temperature inside the fuel injection valve. Therefore, such a deviation can be suppressed by directly measuring the fuel temperature in the vicinity of the fuel injection valve, but in that case, it is necessary to add a sensor, which causes an increase in cost.

In view of such circumstances, the inventor of the present invention has made diligent efforts to compare the feedback amount of idle governor control at the time of idling of the internal combustion engine with a predetermined target value to obtain the correction amount as described above. The present invention has been completed by finding that the deviation can be grasped and the correction amount can be corrected.

That is, the present invention provides a control method for a pressure-accumulation type fuel injection control device and a pressure-accumulation type fuel injection control device in which the accuracy of correction of the control amount of the fuel injection valve is improved after the internal combustion engine is started in a low temperature environment. With the goal.

The "viscosity" in the present specification includes not only "viscosity" defined by fluid dynamics but also functional values related to viscosity such as "kinematic viscosity".

In order to achieve the object of the present invention, the accumulator type fuel injection control device according to the present invention is
A fuel injection valve that injects fuel into an internal combustion engine and
The common rail to which the fuel injection valve is connected and
A high-pressure pump that pumps pressurized high-pressure fuel to the common rail,
Electronic control unit and
In the accumulator type fuel injection control device equipped with
The electronic control unit is
A pre-start viscosity calculation unit that calculates the pre-start viscosity, which is the viscosity of the fuel before the start of the internal combustion engine,
A post-start viscosity calculation unit that calculates the post-start viscosity, which is the viscosity of the fuel after the start of the internal combustion engine, based on the cooling water temperature of the internal combustion engine and the pre-start viscosity.
Idling control for idling operation of the internal combustion engine by injecting a target idle injection amount, which is a fuel injection amount for setting the rotation speed of the internal combustion engine as a target rotation speed, into the internal combustion engine when the internal combustion engine is idling. Department and
A corrected idle injection amount calculation unit that calculates a corrected idle injection amount for compensating for a shortage of the injection amount due to the influence of the viscosity after the start in the target idle injection amount based on the viscosity after the start.
A corrected idle injection amount target value calculation unit that calculates a corrected idle injection amount target value, which is a target value of the corrected idle injection amount, based on the operating condition from the start of the internal combustion engine and the viscosity before the start.
The corrected idle injection is based on a first difference which is a difference between the target idle injection amount and the corrected idle injection amount and a second difference which is a difference between the target idle injection amount and the corrected idle injection amount target value. A correction unit that corrects the amount and
It is configured to include.

Further, in order to achieve the object of the present invention, the control method of the pressure-accumulation type fuel injection control device according to the present invention is:
A fuel injection valve that injects fuel into an internal combustion engine and
The common rail to which the fuel injection valve is connected and
A high-pressure pump that pumps pressurized high-pressure fuel to the common rail,
Electronic control unit and
It is a control method of a pressure-accumulation type fuel injection control device equipped with
The pre-start viscosity calculation unit calculates the pre-start viscosity, which is the viscosity of the fuel before the internal combustion engine is started, and the pre-start viscosity calculation step.
A post-start viscosity calculation step in which the post-start viscosity calculation unit calculates the post-start viscosity, which is the viscosity of the fuel after the start of the internal combustion engine, based on the cooling water temperature of the internal combustion engine and the pre-start viscosity.
When the internal combustion engine is idling, the idling control unit injects a target idle injection amount, which is a fuel injection amount for setting the rotation speed of the internal combustion engine as a target rotation speed, into the internal combustion engine, thereby idling the internal combustion engine. Idling control step to drive and
The corrected idle injection amount calculation unit calculates the corrected idle injection amount for compensating for the shortage of the injection amount due to the influence of the post-start viscosity in the target idle injection amount based on the post-start viscosity. Calculation steps and
The corrected idle injection amount target value calculation unit calculates the corrected idle injection amount target value, which is the target value of the corrected idle injection amount, based on the operating condition from the start of the internal combustion engine and the viscosity before the start. Amount target value calculation step and
The correction unit is based on the first difference, which is the difference between the target idle injection amount and the corrected idle injection amount, and the second difference, which is the difference between the target idle injection amount and the corrected idle injection amount target value. A correction step for correcting the correction idle injection amount and
It is configured to include.

According to the present invention, it is possible to improve the accuracy of correction of the control amount of the fuel injection valve based on the viscosity of the fuel when the internal combustion engine is started in a low temperature environment, as compared with the conventional case.

It is a figure which shows the structural example of the accumulator type fuel injection control apparatus in embodiment of this invention. It is sectional drawing in the axial direction of the combustion injection valve in embodiment of this invention. It is a figure which shows the change of viscosity with change of fuel temperature with respect to 4 kinds of fuels. It is a block diagram which shows the structure of the part which concerns on the embodiment of this invention in the electronic control unit which comprises the accumulator type fuel injection control apparatus. It is a figure for demonstrating the correction with respect to the idling injection amount in a low temperature environment. It is a figure for demonstrating the correction with respect to the idling injection amount in a low temperature environment. It is a subroutine flowchart which shows the correction operation of the correction idle injection amount which concerns on the embodiment of this invention. It is a figure for demonstrating the example of the correction operation of the correction idle injection amount which concerns on the practice of this invention using numerical values.

Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate. The members, arrangements, etc. described below are not limited to the present invention, and can be variously modified within the scope of the gist of the present invention. Further, in each figure, those having the same reference numerals indicate the same elements, and the description thereof is omitted as appropriate. The internal combustion engine in this embodiment is a diesel engine.

FIG. 1 shows the overall configuration of the accumulator fuel injection control device 10 according to the present embodiment. The accumulator fuel injection control device 10 is a device for injecting fuel into a cylinder of an internal combustion engine (not shown) mounted on a vehicle, and includes a fuel tank 1, a low pressure pump 11, a fuel filter 12, and a high pressure. It includes a pump 13, a flow control valve 19, a common rail 15, a pressure control valve 23, a fuel injection valve 17, an electronic control unit 50 (ECU), and the like as main elements.

The low-pressure pump 11 and the high-pressure pump 13 are connected by a low-pressure fuel passage 31, and the high-pressure pump 13 and the common rail 15 and the common rail 15 and the fuel injection valve 17 are connected by high-pressure fuel passages 33 and 35, respectively. Further, return passages 37, 38, and 39 for returning surplus fuel not injected from the fuel injection valve 17 to the fuel tank 1 are connected to the high pressure pump 13, the common rail 15, and the fuel injection valve 17, respectively.

The low-pressure pump 11 sucks up the fuel in the fuel tank 1 and pumps it, and supplies the fuel to the high-pressure pump 13 via the low-pressure fuel passage 31. The low-pressure pump 11 is an in-tank type electric pump provided in the fuel tank 1 and operates by a current supplied from a battery. However, the low-pressure pump 11 may be provided outside the fuel tank 1, or may be provided integrally with the high-pressure pump 13.

A flow rate control valve 19 for adjusting the discharge amount of the high-pressure pump is provided at the inlet portion of the low-pressure fuel in the high-pressure pump 13. For the flow rate control valve 19, for example, an electromagnetic proportional control valve in which the stroke amount of the valve member is variable according to the supply current value and the area of the fuel passage path can be adjusted is used.

The high-pressure pump 13 pressurizes the fuel introduced through the flow control valve 19 by the low-pressure pump 11 and pumps it to the common rail 15 via the high-pressure fuel passage 33.

The common rail 15 stores fuel in a high-pressure state pressurized by the high-pressure pump 13 and supplies fuel to each fuel injection valve 17 connected via the high-pressure fuel passage 35. A rail pressure sensor 25 and a pressure control valve 23 are attached to the common rail 15.

The rail pressure sensor 25 detects the pressure (rail pressure) in the common rail 15. The sensor signal of the rail pressure sensor 25 is sent to the electronic control unit 50.

The pressure control valve 23 is used to adjust the rail pressure by adjusting the flow rate of the high pressure fuel returned from the common rail 15 to the fuel tank 1. For the pressure control valve 23, for example, an electromagnetic proportional control valve is used in which the stroke amount of the valve member for opening and closing the fuel passage is variable according to the supply current value and the area of the fuel passage path can be adjusted. Further, instead of the pressure control valve 23, a mechanical safety valve that opens when a predetermined pressure is reached may be used.

The fuel injection valve 17 includes a nozzle body provided with an injection hole and a nozzle needle that opens and closes the injection hole by moving forward and backward. The fuel injection valve 17 closes the injection hole by applying a back pressure to the rear end side of the nozzle needle, while the injection hole is opened by releasing the applied back pressure. As the back pressure control means of the fuel injection valve 17 in the present invention, an electromagnetic solenoid type actuator is used.

The electronic control unit 50 has a storage element such as a RAM or a ROM centered on a microcomputer having a known configuration, and is connected to a drive circuit for driving the fuel injection valve 17, a flow control valve 19, and a pressure control valve 23. It is equipped with an energization circuit for energizing. Further, in addition to the detection signal of the rail pressure sensor 25 being input to the electronic control unit 50, various detection signals such as the rotation speed of the internal combustion engine, the accelerator opening, and the fuel temperature are used for operation control and fuel injection control of the internal combustion engine. It is designed to be entered for use in.

Next, the fuel injection valve 17 according to the embodiment of the present invention will be described with reference to FIG. FIG. 2 schematically shows a cross section of the fuel injection valve 17 in the axial direction.

The fuel injection valve 17 includes a fuel injection valve main body 130, a nozzle 131 attached to the tip side of the fuel injection valve main body 130, and a solenoid valve 132 attached to the opposite side of the fuel injection valve main body 130 facing the nozzle 131. Is provided as the main component.

In the description of the fuel injection valve 17 in the present specification, the solenoid valve 132 side is the upper side and the opposite side, that is, the nozzle 131 side is the lower side when viewed from the fuel injection valve main body 130.

Inside the nozzle 131, a nozzle needle 133 slidably arranged in the axial direction of the nozzle 131 is arranged. A valve piston 134 is arranged above the nozzle needle 133. The valve piston 134 is slidably arranged in the fuel injection valve main body 130 in the axial direction of the fuel injection valve main body 130.

The end of the valve piston 134 opposite to the nozzle needle 133 is housed in the valve body 135. In the valve body 135, a control chamber 136 in which the end portion of the valve piston 134 is arranged is defined.

The control chamber 136 communicates with the high-pressure connection portion 137 to which fuel is supplied from the common rail 15 via an orifice formed in the valve body 135. The high-pressure connecting portion 137 further communicates with the flow path 138 and is connected to the nozzle sheet portion 139 between the nozzle 131 and the tip of the nozzle needle 133 via the flow path 138. The nozzle needle 133 is urged toward the nozzle seat portion 139 by the nozzle spring 133a. The control chamber 136, the flow path 138, the nozzle sheet section 139, etc. that communicate with the high-voltage connection section 137 are referred to as high-voltage flow paths.

The solenoid valve 132 has a magnet 140 which is a solenoid coil, and an armature 141 made of a magnetic material is arranged on the lower end side of the magnet 140. The armature 141 is arranged so as to be slidable inside the guide portion 142 formed in the valve body 135.

A circular valve seat 143 on which the lower end of the armature 141 is seated is formed on the lower end side of the armature 141. A valve spring 145 that urges the armature 141 toward the valve seat 143 is housed in the upper part of the armature 141.

An orifice 144 communicating with the control chamber 136 is opened in the center of the valve seat 143. The armature 141 moves upward so as to open the orifice 144 by energizing the magnet 140 of the fuel injection valve 17. A power supply connection portion 146 is further provided on the upper portion of the solenoid valve 132.

The fuel injection valve 17 has stopped energizing the magnet 140 in a non-fuel injection state. At this time, the armature 141 is seated on the valve seat 143 by the valve spring 145, and the orifice 144 is closed. Then, the control chamber 136 is filled with the high-pressure fuel from the common rail 15, and the nozzle sheet portion 139 is also filled with the high-pressure fuel. In this state, the nozzle needle 133 has the nozzle seat portion 139 due to the force generated from the difference in the pressure receiving area of the fuel acting on the control chamber 136 and the nozzle seat portion 139 side and the resultant force of the urging forces acting by the nozzle spring 133a. The nozzle sheet portion 139 is urged to the side and is in a closed state. Therefore, no fuel is injected.

When the magnet 140 is energized from the non-energized state of the magnet 140, the fuel injection valve 17 is in the injection state. At this time, the armature 141 is attracted by the magnetic force of the magnet 140 and rises. As the armature 141 rises, the orifice 144 is opened, and the high-pressure fuel in the control chamber 136 flows out to the upper part of the control chamber 136 through the orifice 144. As a result, the pressure in the control chamber 136 is lowered, and the upward force due to the high-pressure fuel filled in the nozzle seat portion 139 side overcomes the downward force acting by the control chamber 136 and the nozzle spring 133a, and the nozzle needle 133. To raise. Therefore, the fuel is injected from the tip of the nozzle 131.

In the present invention, the fuel injection valve 17 is used to grasp the viscosity of the fuel. That is, before cranking at the start of the internal combustion engine, the fuel injection valve 17 is energized to open and close the internal solenoid valve 132.

At that time, the time from the time when the energization is cut off until the induced electromotive force generated in the solenoid valve 132 after the energization is cut off reaches its peak, that is, the time until the solenoid valve 132 is closed is set by the solenoid valve 132. Measured as valve closing time. Then, the difference between the closing time of the solenoid valve 132 and the standard time measured in advance is calculated, and the viscosity of the fuel is calculated from the time difference.

The relationship between the difference between the closing time of the solenoid valve and the standard time and the viscosity of the fuel can be set by a test, a simulation, or the like.

The viscosity of the fuel grasped by the above method is used in the electronic control unit 50 to correct the control amount of the fuel injection valve 17 (details will be described later).

Here, the viscosity of the fuel will be described with reference to FIG. FIG. 3 shows changes in viscosity of four types of fuel, that is, light oil, as the fuel temperature changes. It is known that the viscosity of light oil differs depending on the type of light oil even at the same temperature. It is also known that the viscosity increases as the fuel temperature decreases, and the difference between the types of light oil increases.

As described above, the reason why light oils having different viscosities exist even at the same temperature is that the properties of light oils differ depending on the country or region or the manufacturer.

INDUSTRIAL APPLICABILITY The present invention enhances the correction accuracy in correcting the control amount of the fuel injection valve corresponding to the viscosity of the fuel, which differs depending on the type and temperature of the fuel.

Next, a configuration example of the electronic control unit 50 according to the embodiment of the present invention will be described with reference to FIG. FIG. 4 is a block diagram schematically showing the configuration of a portion of the electronic control unit 50 according to the implementation of the present invention.

The electronic control unit 50 includes a pre-start viscosity calculation unit 502, a post-start viscosity calculation unit 504, a normal control unit 506, a correction normal control injection amount calculation unit 508, an idling control unit 510, and a correction idle injection amount calculation unit. It includes 512, a correction idle injection amount target value calculation unit 514, and a correction unit 516.

The pre-start viscosity calculation unit 502 calculates the pre-start viscosity, which is the viscosity of the fuel before the internal combustion engine is started. As described above, the method for calculating the viscosity before starting is to obtain the closing time of the solenoid valve 132 by energizing the fuel injection valve 17 before cranking at the time of starting the internal combustion engine, and measure the viscosity in advance. Calculate the viscosity of the fuel based on the difference from the standard time. The pre-start viscosity calculation unit 502 stores the calculated pre-start viscosity in a predetermined area of the electronic control unit 50.

The post-start viscosity calculation unit 504 calculates the post-start viscosity, which is the viscosity of the fuel after the start of the internal combustion engine. Specifically, the viscosity of the current fuel is estimated based on the viscosity before starting calculated by the viscosity calculation unit 502 before starting, the cooling water temperature of the internal combustion engine when the viscosity before starting is calculated, and the current cooling water temperature. To do.

More specifically, the pre-start viscosity, the cooling water temperature of the internal combustion engine when the pre-start viscosity is calculated, and the change characteristics of the fuel viscosity as the cooling water temperature of the fuel rises after the start of the internal combustion engine are tested in advance. Or by simulation. Then, the viscosity before starting, the cooling water temperature of the internal combustion engine when calculating the viscosity after starting, and the cooling water temperature of the internal combustion engine when the viscosity before starting is calculated are used as input values, and the viscosity after starting is performed by map search or the like. To estimate. Further, the viscosity after starting immediately after starting the internal combustion engine matches the viscosity before starting. The post-start viscosity calculation unit 504 stores the calculated post-start viscosity in a predetermined region of the electronic control unit 50.

Further, as shown in FIG. 3, the viscosity of the fuel decreases as the fuel temperature rises. Therefore, the post-start viscosity calculated by the post-start viscosity calculation unit 504 becomes smaller as the operating time of the internal combustion engine elapses.

The normal control unit 506 controls the accumulator fuel injection control device 10 when the internal combustion engine is in an operating state other than idling. Specifically, the normal control unit 506 calculates the target injection amount from the accelerator opening, the vehicle speed, and the like, and calculates the energization time for the fuel injection valve 17 corresponding to the target injection amount in consideration of the rail pressure. , Fuel injection.

The idling control unit 510 feedback-controls the fuel injection amount injected from the fuel injection valve 17 so that the idling speed of the internal combustion engine becomes a predetermined target rotation speed when the internal combustion engine is idling. This feedback control is also hereinafter referred to as "idle governor control".

The correction normal control injection amount calculation unit 508 is a correction amount for suppressing the influence on the injection amount due to the viscosity of the fuel in the operating region other than idling when the internal combustion engine is started in a low temperature environment. A certain corrected normal control injection amount is calculated.

The correction idle injection amount calculation unit 512 is a correction amount for suppressing the influence on the injection amount due to the viscosity of the fuel during idling when the internal combustion engine is started in a low temperature environment. Calculate the injection amount.

The corrected normal control injection amount calculated by the corrected normal control injection amount calculation unit 508 is notified to the normal control unit 506 and is used for operation control of the internal combustion engine other than when idling. The corrected idle injection amount calculated by the correction idle injection amount calculation unit 512 is notified to the idling control unit 510 and is used for idling control.

It is known that the correction amount corresponding to the operating region other than idling in a low temperature environment correlates with the correction amount corresponding to idling. Therefore, this correlation is grasped in advance, and the correction normal control injection amount calculation unit 508 calculates the correction normal control injection amount used in the operation region other than idling based on the correction idle injection amount and the correlation.

In addition, what kind of environment should be corrected as a low temperature environment depends on the specifications of the internal combustion engine and the specifications of the vehicle on which the internal combustion engine is installed. For example, when starting the vehicle when the outside air temperature is 5 degrees below freezing. Can be done.

FIG. 5 is a bar graph showing the injection amount at the time of idling. Q1 is a target idle injection amount, which is an injection amount required for the internal combustion engine to maintain the idling speed, which is calculated by the idling control unit 510. The target idle injection amount Q1 is calculated based on the torque required for the internal combustion engine to maintain the idling speed.

When correction in a low temperature environment is not required, the idling control unit 510 calculates the energization time ET1 for injecting the target idle injection amount Q1 and energizes the fuel injection valve 17 with the energization time ET1. However, in a low temperature environment, the viscosity of the fuel is high, so that the actual fuel injection amount decreases in the same energization time as at room temperature (for example, 20 degrees Celsius).

The corrected injection amount for compensating for the decrease in the injection amount is the corrected idle injection amount Q1_cor. The corrected idle injection amount Q1_cor is based on the viscosity before the start of the fuel at the time of starting the internal combustion engine, and based on the viscosity after the start of the fuel after the start of the internal combustion engine, based on a predetermined calculation formula or the like. It is calculated. Further, the corrected idle injection amount Q1_cor gradually decreases as time elapses after the start of the internal combustion engine, and finally becomes zero. This is because the viscosity gradually decreases after the start of the internal combustion engine as time passes, and it is not necessary to consider the influence on the fuel injection amount.

Q1_gov in FIG. 5 is the idle governor injection amount calculated by the idle governor control. That is, at the time of idling, the target idling speed of the internal combustion engine is maintained by the sum of the corrected idle injection amount Q1_cor, which is the correction amount based on the viscosity of the fuel, and the idle governor injection amount Q1_gov.

That is, the idling control unit 510 injects the target idle injection amount Q1 in a low temperature environment by energizing the fuel injection valve 17 with the energization time obtained by adding the energization time ET1_cor corresponding to the corrected idle injection amount Q1_cor to the ET1. To do.

By the way, as described above, depending on the environment in which the vehicle equipped with the internal combustion engine is used, the correlation between the rate of increase in the cooling water temperature and the rate of increase in the fuel temperature inside the fuel injection valve after the start of the internal combustion engine has been developed. There is a possibility that it may deviate from what was grasped based on tests etc. at the stage. In that case, the post-start viscosity calculated by the post-start viscosity calculation unit 504 will be different from the actual viscosity of the fuel. For example, if the rate of increase in the fuel temperature inside the fuel injection valve is slower than expected with respect to the rate of increase in the cooling water temperature, the electronic control unit 50 will overestimate the fuel temperature inside the fuel injection valve. .. As a result, the viscosity after starting is calculated as a value smaller than the actual value, and the corrected idle injection amount Q1_cor becomes too small. Further, if the rate of increase in the fuel temperature inside the fuel injection valve is faster than expected with respect to the rate of increase in the cooling water temperature, the electronic control unit 50 will estimate the fuel temperature inside the fuel injection valve to be lower than the actual temperature. .. As a result, the viscosity after starting is calculated as a value larger than the actual value, and the corrected idle injection amount Q1_cor becomes excessive.

In this way, even when the corrected idle injection amount Q1_cor is calculated based on a value different from the actual viscosity of the fuel, the idle governor injection amount Q1_gov is corrected by the feedback by the idle governor control during idling. The target idling speed is maintained.

However, the corrected normal control injection amount, which is the correction amount in the operating region other than idling, is calculated based on the correlation between the corrected normal control injection amount and the corrected idle injection amount Q1_cor, which is grasped in advance. Therefore, in the operating region other than idling, if the corrected idle injection amount Q1_cor deviates from the originally expected value, in other words, the correction amount of the injection amount corresponding to the viscosity of the fuel at that time, the deviation is other than idling. It affects the injection amount in the operating area.

Therefore, in the present invention, the idle governor control during idling is used to correct the deviation of the corrected idle injection amount Q1_cor from the original value described above, so that the injection amount in the operating region other than idling is appropriate. Shall be.

The details will be described below. In the present invention, the corrected idle injection amount target value calculation unit 514 shown in FIG. 4 calculates the corrected idle injection amount target value, which is the target value of the corrected idle injection amount. Then, even if there is a discrepancy between the corrected idle injection amount target value calculated by the corrected idle injection amount target value calculation unit 514 and the corrected idle injection amount calculated by the corrected idle injection amount calculation unit 512, FIG. The correction unit 516 shown in the above corrects this deviation by using a correction coefficient described later so that the correction idle injection amount becomes the correction idle injection amount target value.

The corrected idle injection amount target value Q1_c1 and the idle governor injection amount target value Q1_g1 calculated by the correction idle injection amount target value calculation unit 514 will be described with reference to FIG. 6A. In FIG. 6A, Q1 is a target idle injection amount, which is a fuel injection amount required to maintain the idling speed, calculated by the idling control unit 510.

The corrected idle injection amount target value calculation unit 514 calculates the current fuel viscosity based on the pre-start viscosity calculated by the pre-start viscosity calculation unit 502 when the internal combustion engine is started and the operating condition after the internal combustion engine is started. To do. Various factors can be used for the operating state of the internal combustion engine, and for example, the elapsed time after the start of the internal combustion engine, the number of injections, the integrated value of the injection amount, and the like can be used. Further, the relationship between the viscosity before starting, the operating condition after starting the internal combustion engine, and the current viscosity of the fuel can be grasped in advance by a test or a simulation.

The corrected idle injection amount target value calculation unit 514 is an injection amount for compensating for the decrease in the injection amount in a low temperature environment from the current viscosity of the fuel calculated based on the viscosity before the start and the operating condition after the start of the internal combustion engine. Is calculated as the correction idle injection amount target value Q1_c1.

Further, in FIG. 6A, the difference between the target idle injection amount Q1 and the corrected idle injection amount target value Q1_c1 is the idle governor injection amount target value Q1_g1, which is the target value of the idle governor injection amount Q1_gov. Further, the correction idle injection amount target value Q1_c1 gradually decreases as time elapses after the start of the internal combustion engine, and finally becomes zero. This is because the viscosity of the fuel gradually decreases as time passes after the start of the internal combustion engine, and it is not necessary to consider the influence on the fuel injection amount.

Next, FIG. 6B will be described. Q1_cor in FIG. 6B is the corrected idle injection amount calculated by the correction idle injection amount calculation unit 512, and Q1_gov is the idle governor injection amount calculated by the idle governor control. Note that FIGS. 6A and 6B are calculated by different routines at the same timing during the operation of the internal combustion engine.

FIG. 6B shows a case where the correlation between the rate of increase in the cooling water temperature and the rate of increase in the fuel temperature inside the fuel injection valve deviates from the assumption, and the fuel inside the fuel injection valve is relative to the rate of increase in the cooling water temperature. The case where the temperature rise rate is faster than expected is shown. In this case, the electronic control unit 50 estimates the fuel temperature inside the fuel injection valve to be lower than the actual temperature. As a result, the post-start viscosity calculated by the post-start viscosity calculation unit 504 is calculated as a value larger than the actual viscosity. Therefore, in the corrected idle injection amount calculation unit 512, the corrected idle injection amount Q1_cor calculated from the viscosity after starting becomes larger than the originally required value.

The correction unit 516 corrects the corrected idle injection amount Q1_cor in FIG. 6B so that it becomes the corrected idle injection amount target value Q1_c1 in FIG. 6A. Specifically, the correction unit 516 calculates a correction coefficient described later, and multiplies the correction coefficient by the correction idle injection amount Q1_cor calculated by the correction idle injection amount calculation unit 512.

The calculation of the corrected idle injection amount target value Q1_c1 and the correction of the corrected idle injection amount Q1_cor using the corrected idle injection amount target value Q1_c1 are such that the internal combustion engine is in an idling state while the correction in a low temperature environment is required. It is done every time. Then, this amendment is continued until a predetermined condition is satisfied. The predetermined condition is, for example, when the cooling water temperature of the internal combustion engine exceeds a predetermined value, or when the operating time of the internal combustion engine exceeds a predetermined time, or the calculated corrected idle injection amount target value Q1_c1 is set. When it reaches zero, it can be.

Next, the calculation of the correction coefficient executed by the correction unit 516 and the correction of the correction idle injection amount Q1_cor will be described with reference to FIG. 7. When the processing by the correction unit 516 is started, in step S102, the correction unit 516 sets n = 1 as the count value of the correction coefficient calculation and the correction number of the correction idle injection amount Q1_cor. In the subsequent flow, A (n) is the correction coefficient calculated at the nth time, and Q1_cor (n) is the correction idle injection amount corrected at the nth time. Further, A (n-1) in step S102, that is, A (0) is set to 1.

In step S104 following step S102, the correction unit 516 determines whether or not the injection amount correction in a low temperature environment can be executed. If it is determined in step S104 that the correction is feasible (YES), the process proceeds to step S106, while if it is determined that the correction is not feasible (NO), the process returns to the main routine (not shown). ..

In step S104, the correction unit 516 determines whether or not correction in a low temperature environment is possible as described below. First, it is determined whether or not the injection amount correction in a low temperature environment is necessary. As described above, the condition that requires the injection amount correction in a low temperature environment can be, for example, when the outside air temperature is 5 degrees or less below the freezing point. Further, in step S104, the correction unit 516 also determines whether or not information necessary for correcting the injection amount in a low temperature environment, such as the viscosity before starting, the cooling water temperature at the time of starting the internal combustion engine, and the viscosity after starting, is obtained. .. When these conditions are satisfied, the process proceeds to the subsequent step S106.

In step S106, the correction unit 516 determines whether or not the internal combustion engine is in an idling state. If it is determined in step S106 that the internal combustion engine is in an idling state (YES), the process proceeds to step S108, while if it is determined that the internal combustion engine is not in an idling state (NO), step S114 is performed. Proceed to processing.

In step S108, the correction unit 516 presents the correction coefficient A (n-1) calculated last time, the idle governor injection amount Q1_gov (n-1) calculated last time, and the idle governor injection amount target value Q1_g1. The correction coefficient A (n) is obtained. Specifically, the correction unit 516 obtains A (n) by multiplying the value obtained by dividing Q1_gov (n-1) by Q1_g1 by A (n-1). Further, as the idle governor injection amount target value Q1_g1 used in this step, a value calculated by another routine is used at the time of executing this flow.

Here, when the calculation of the correction coefficient this time is the first time, A (n-1) and Q1_act (n-1) in step S108 are set as follows. First, A (n-1) is set to A (n-1) = A (0) = 1 as set in step S102. Further, Q1_gov (n-1), that is, Q1_gov (0) is an idle governor injection amount calculated by idle governor control before the execution of this flow.

On the other hand, in step S114, the value A (n-1) calculated in the previous step S108 is set as the correction coefficient A (n) this time. Further, when the step S114 is entered without passing through the step S108, the correction coefficient A (n) is set to the value set in the step S102, that is, 1. In step S108 following step S108 or step S114, the correction unit 516 calculates the correction idle injection amount Q1_cor (1), which is the first correction value of the correction idle injection amount Q1_cor. Specifically, the correction unit 516 multiplies the correction idle injection amount Q1_cor (0) calculated by the correction idle injection amount calculation unit 512 by the correction coefficient A (n) before the execution of this flow. The corrected idle injection amount Q1_cor (1) this time is calculated. Here, when the step S108 is entered through step S108, the correction coefficient A (n) calculated in step S108 is used, while when the step S110 is entered through step S114, the correction coefficient A (n) is set in step S114. The correction coefficient A (n) is used.

In the subsequent step S112, the number of corrections is incremented by 1, n = n + 1, and the processes after step S104 are repeated.

In step S110, the corrected idle injection amount Q1_cor (n) corrected by the correction unit 516 is notified to the idling control unit 510 and used for idling control in the idling control unit 510.

Further, as described above, it is known that the correction amount corresponding to the operating region other than idling correlates with the correction amount corresponding to the idling in a low temperature environment. Therefore, the correction idle injection amount Q1_cor (n) calculated by the correction unit 516 in step S110 is also notified to the correction normal control injection amount calculation unit 508. The correction normal control injection amount calculation unit 508 is based on the correction idle injection amount Q1_cor (n) notified by the correction unit 516, and uses a predetermined calculation formula, a map search, or the like to perform correction normal control injection in an operation region other than idling. The amount is calculated, and the corrected normal control injection amount is used for injection amount control in the normal control unit 506.

Next, an example of the correction of the corrected idle injection amount Q1_cor described with reference to FIG. 7 will be described with reference to FIG. 8 using actual numerical values. In FIG. 8, a simple numerical value is used for easy understanding, and the target idle injection amount Q1 = 10 (mg).

FIG. 8A shows the idle governor injection amount target value Q1_g1 and the corrected idle injection amount target value Q1_c1 calculated by the corrected idle injection amount target value calculation unit 514. In this example, the idle governor injection amount target value Q1_g1 = 7 (mg) and the corrected idle injection amount target value Q1_c1 = 3 (mg).

FIG. 8B shows an example of the correction process of the correction idle injection amount Q1_cor executed by the correction unit 516. In FIG. 8B, n (loop) indicates the number of correction processes for the correction idle injection amount Q1_cor. Therefore, n = 0 indicates the state before the execution of the correction shown in FIG. In this example, the idle governor injection amount Q1_gov (0) = 5 (mg) and the corrected idle injection amount Q1_cor (0) = 5 (mg).

FIG. 8B shows a case where the correlation between the rate of increase in the cooling water temperature and the rate of increase in the fuel temperature inside the fuel injection valve deviates from the assumption, and the fuel inside the fuel injection valve is relative to the rate of increase in the cooling water temperature. An example is shown in which the temperature rise rate is faster than expected. In this case, the electronic control unit 50 estimates the fuel temperature inside the fuel injection valve to be lower than the actual temperature. As a result, the post-start viscosity calculated by the post-start viscosity calculation unit 504 is calculated as a value larger than the actual viscosity. Therefore, in the correction idle injection amount calculation unit 512, the correction idle injection amount Q1_cor (0) = 5 calculated from the viscosity after starting is larger than the correction idle injection amount target value Q1_c1 = 3.

Subsequently, the first correction process (n = 1) will be described. When n = 1 and A (n-1) = 1 are set in step S102 of FIG. 7 and YES is determined in subsequent steps S104 and S106, the corrected idle injection amount Q1_cor is determined in subsequent steps S108 and S110. The first correction process is executed.
Since A (0) = 1, Q1_gov (0) = 5, and Q1_g1 = 7 in step S108,
A (1) = 1 × 5/7 = 0.714.

In the following step S110, since Q1_cor (0) = 5 and A (1) = 0.714,
Q1_cor (1) = 5 × 0.714 = 3.57 (mg).

At this time, the idle governor injection amount Q1_gov is
It is calculated as Q1_gov (1) = 10-3.57 = 6.43 (mg) and used for the second correction process (n = 2).

In the second correction process, since A (1) = 0.714, Q1_gov (1) = 6.43, and Q1_g1 = 7 in step S108,
A (2) = 0.714 × 6.43 / 7 = 0.656.

In the following step S110, Q1_cor (0) = 5 and A (2) = 0.656.
Q1_cor (2) = 5 × 0.656 = 3.28 (mg).

At this time, the idle governor injection amount Q1_gov is
It is calculated as Q1_gov (2) = 10-3.28 = 6.72 (mg) and used for the third correction process (n = 3).

As described above, when the correction process of the correction idle injection amount Q1_cor is repeated, the correction coefficient A (n) converges to 0.6. Therefore, after that, in step S110,
Q1_cor (n) = Q1_cor (0) × 0.6 = 5 × 0.6 = 3.

That is, the corrected idle injection amount Q1_cor is corrected to the corrected idle injection amount target value Q1_c1.

As described above, according to the present invention, even if the rise of the cooling water is unexpected when the internal combustion engine is started in a low temperature environment, the correction idle injection amount calculation unit 512 calculates it. The corrected idle injection amount Q1_cor is corrected to the corrected idle injection amount target value Q1_c1.

Further, since the corrected idle injection amount Q1_cor corrected to the corrected idle injection amount target value Q1_c1 is notified to the corrected normal control injection amount calculation unit 508, the injection amount control in a low temperature environment is appropriate in the operation region other than idling. Will be done.

Further, according to the present invention, since the correction amount per correction with respect to the correction idle injection amount Q1_cor can be reduced, it is possible to suppress the generation of vibration and the sudden fluctuation of the rotation speed by executing this correction. it can.

Further, in order to make the correction according to the present invention smoother, an upper limit value may be set for the correction amount per correction. For example, the difference between Q1_cor (n) and Q1_cor (n-1) can be prevented from exceeding 1 (mg). Explaining with the example of FIG. 8B, the difference between Q1_cor (0) and Q1_cor (1) exceeds 1 (mg). In such a case, Q1_cor (1) may be forcibly set to 4 (mg) and the subsequent processing may be continued.

Further, in FIGS. 6 to 8, the case where the fuel temperature inside the fuel injection valve rises faster than expected with respect to the cooling water temperature rise rate is shown, but the fuel injection valve has a fuel injection valve with respect to the cooling water temperature rise rate. Similar corrections can be made even if the internal fuel temperature rises slower than expected.

10: Accumulation type fuel injection control device, 13: High pressure pump, 15: Common rail, 17: Fuel injection valve, 50: Electronic control unit, 502: Pre-start viscosity calculation unit, 504: Post-start viscosity calculation unit, 510: Idling control Unit 512: Corrected idle injection amount calculation unit 514: Corrected idle injection amount target value calculation unit 516: Correction unit

Claims (4)

A fuel injection valve that injects fuel into an internal combustion engine and
The common rail to which the fuel injection valve is connected and
A high-pressure pump that pumps pressurized high-pressure fuel to the common rail,
Electronic control unit and
In the accumulator type fuel injection control device equipped with
The electronic control unit is
A pre-start viscosity calculation unit that calculates the pre-start viscosity, which is the viscosity of the fuel before the start of the internal combustion engine,
A post-start viscosity calculation unit that calculates the post-start viscosity, which is the viscosity of the fuel after the start of the internal combustion engine, based on the cooling water temperature of the internal combustion engine and the pre-start viscosity.
Idling control that performs idling operation of the internal combustion engine by injecting a target idle injection amount, which is a fuel injection amount for setting the rotation speed of the internal combustion engine as a target rotation speed, into the internal combustion engine when the internal combustion engine is idling. Department and
A corrected idle injection amount calculation unit that calculates a corrected idle injection amount for compensating for a shortage of the injection amount due to the influence of the viscosity after the start in the target idle injection amount based on the viscosity after the start.
A corrected idle injection amount target value calculation unit that calculates a corrected idle injection amount target value, which is a target value of the corrected idle injection amount, based on the operating condition from the start of the internal combustion engine and the viscosity before the start.
The corrected idle injection is based on a first difference which is a difference between the target idle injection amount and the corrected idle injection amount and a second difference which is a difference between the target idle injection amount and the corrected idle injection amount target value. A correction unit that corrects the amount and
Accumulation type fuel injection control device including. A claim that the correction unit calculates a correction coefficient by dividing the first difference by the second difference, and corrects the correction idle injection amount by multiplying the correction coefficient by the correction idle injection amount. The accumulator type fuel injection control device according to 1. The correction unit repeatedly updates the correction coefficient and the correction idle injection amount, calculates the correction idle injection amount this time from the product of the initial value of the correction idle injection amount and the correction coefficient this time, and performs the target idle injection amount. The accumulator fuel injection control device according to claim 2, wherein the next correction coefficient is calculated by multiplying the current correction coefficient by a value obtained by dividing the difference between the amount and the current correction idle injection amount by the second difference. A fuel injection valve that injects fuel into an internal combustion engine and
The common rail to which the fuel injection valve is connected and
A high-pressure pump that pumps pressurized high-pressure fuel to the common rail,
Electronic control unit and
It is a control method of a pressure-accumulation type fuel injection control device equipped with
The pre-start viscosity calculation unit calculates the pre-start viscosity, which is the viscosity of the fuel before the internal combustion engine is started, and the pre-start viscosity calculation step.
A post-start viscosity calculation step in which the post-start viscosity calculation unit calculates the post-start viscosity, which is the viscosity of the fuel after the start of the internal combustion engine, based on the cooling water temperature of the internal combustion engine and the pre-start viscosity.
When the internal combustion engine is idling, the idling control unit injects a target idle injection amount, which is a fuel injection amount for setting the rotation speed of the internal combustion engine as a target rotation speed, into the internal combustion engine, thereby idling the internal combustion engine. Idling control step to drive and
The corrected idle injection amount calculation unit calculates the corrected idle injection amount for compensating for the shortage of the injection amount due to the influence of the post-start viscosity in the target idle injection amount based on the post-start viscosity. Calculation steps and
The corrected idle injection amount target value calculation unit calculates the corrected idle injection amount target value, which is the target value of the corrected idle injection amount, based on the operating condition from the start of the internal combustion engine and the viscosity before the start. Amount target value calculation step and
The correction unit is based on the first difference, which is the difference between the target idle injection amount and the corrected idle injection amount, and the second difference, which is the difference between the target idle injection amount and the corrected idle injection amount target value. A correction step for correcting the correction idle injection amount and
Control method of accumulator type fuel injection control device including.

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