JP7387556B2 - Fuel injection control device and control method for the fuel injection control device - Google Patents

Description

The present invention relates to a fuel injection control device and a method of controlling the fuel injection control device for injecting fuel into a cylinder of an internal combustion engine.

2. Description of the Related Art Conventionally, a pressure accumulation type fuel injection control device is known as a device for supplying fuel to an internal combustion engine. The pressure accumulation type fuel injection control device includes a low pressure pump, a high pressure pump, a common rail, a fuel injection valve, an electronic control unit (ECU), etc. as main elements. In a pressure accumulation type fuel injection control device, fuel in a fuel tank is sent to a high pressure pump by a low pressure pump, pressurized by the high pressure pump, and sent to a common rail, and high pressure fuel is supplied from the common rail to a fuel injection valve. Then, by controlling the energization of the fuel injection valve in this state, fuel is supplied to the internal combustion engine.

As the low-pressure pump in the pressure accumulation type fuel injection control device, an electric pump driven by electricity may be used (see, for example, Patent Document 1).

JP2011-236791

As an electric low-pressure pump, a relatively inexpensive type that is driven by a voltage applied from a battery or an alternator and whose discharge amount is not adjusted during operation is sometimes used. In such a low-pressure pump, when the battery or alternator deteriorates and the applied voltage decreases, the amount of fuel discharged decreases. Furthermore, due to deterioration of the fuel filter disposed between the low-pressure pump and the high-pressure pump, resistance to passing fuel may increase and the discharge amount of the low-pressure pump may decrease.

When the discharge amount of the low-pressure pump decreases, a situation may occur in which the required fuel is not supplied to the high-pressure pump. As a result, there is a possibility that the accuracy of controlling the fuel pressure inside the common rail (hereinafter also referred to as rail pressure) may decrease. Furthermore, if the high-pressure pump is of a type that is lubricated with fuel, the inside of the high-pressure pump may not be properly lubricated, which may accelerate wear of parts inside the high-pressure pump.

The present invention has been made against the background of the above-mentioned problems, and is intended to make it possible to detect when the discharge amount of a low-pressure pump is insufficient in a pressure accumulation type fuel injection control device.

The fuel injection control device according to the present invention includes:
a fuel injection valve that supplies fuel to an internal combustion engine;
a common rail to which the fuel injection valve is connected;
a high-pressure pump that pumps pressurized high-pressure fuel to the common rail;
an electric low pressure pump that supplies fuel from the fuel tank to the high pressure pump;
a flow control valve that is included in the high-pressure pump and adjusts the amount of fuel pumped by the high-pressure pump;
an electronic control unit;
In a fuel injection control device equipped with
The electronic control unit includes:
a flow rate control valve control unit that performs feedback control so that the fuel pressure in the common rail reaches a target value by controlling the flow rate control valve;
a discharge amount calculation unit that calculates a discharge amount of the low pressure pump from a fuel temperature and a voltage value applied to the low pressure pump;
a discharge amount decrease calculation unit that calculates a decrease in the discharge amount of the low-pressure pump due to deterioration of the fuel filter;
The actual discharge amount, which is the actual discharge amount of the low-pressure pump, is calculated from the discharge amount of the low-pressure pump calculated by the discharge amount calculation section and the decrease in the discharge amount of the low-pressure pump calculated by the discharge amount decrease calculation section. an actual discharge amount calculation unit that calculates the amount;
a required discharge amount calculation unit that calculates a required discharge amount that is a discharge amount of the low-pressure pump that is required by the fuel injection control device;
a determination unit that determines that the low-pressure pump is abnormal when the actual discharge amount is less than the required discharge amount;
This includes:

A method for controlling a fuel injection control device according to the present invention includes:
a fuel injection valve that supplies fuel to an internal combustion engine;
a common rail to which the fuel injection valve is connected;
a high-pressure pump that pumps pressurized high-pressure fuel to the common rail;
an electric low pressure pump that supplies fuel from the fuel tank to the high pressure pump;
a flow control valve that is included in the high-pressure pump and adjusts the amount of fuel pumped by the high-pressure pump;
an electronic control unit;
A method for controlling a fuel injection control device comprising:
a flow rate control step in which a flow rate control valve control unit performs feedback control by controlling the flow rate control valve so that the fuel pressure in the common rail reaches a target value;
a discharge amount calculation step in which a discharge amount calculation unit calculates a discharge amount of the low pressure pump from a fuel temperature and a voltage value applied to the low pressure pump;
a discharge amount decrease calculation step in which the discharge amount decrease calculation unit calculates a decrease in the discharge amount of the low-pressure pump due to deterioration of the fuel filter;
An actual discharge amount calculation section calculates the actual output of the low pressure pump from the discharge amount of the low pressure pump calculated by the discharge amount calculation section and the decrease in the discharge amount of the low pressure pump calculated by the discharge amount decrease calculation section. an actual discharge amount calculation step of calculating an actual discharge amount that is a discharge amount of
a necessary discharge amount calculation step in which the required discharge amount calculation unit calculates a required discharge amount that is a discharge amount of the low-pressure pump required by the fuel injection control device;
a determination step in which the determination unit determines that the low-pressure pump is abnormal when the actual discharge amount is less than the required discharge amount;
This includes:

According to the present invention, in the pressure accumulation type fuel injection control device, when the discharge amount of the electric low-pressure pump that supplies fuel from the fuel tank to the high-pressure pump is insufficient, without adding a new device, this can be done quickly. can be detected.

1 is a diagram showing a configuration example of a fuel injection control device according to an embodiment of the present invention. FIG. 2 is a diagram for explaining characteristics of a low-pressure pump 2 according to an embodiment of the present invention. FIG. 2 is a block diagram showing the configuration of a portion of the electronic control unit that constitutes the fuel injection control device, which is related to the implementation of the present invention. FIG. 3 is a diagram for explaining abnormality determination of the low pressure pump 2 according to the embodiment of the present invention. It is a flowchart which shows the process after abnormality determination of the low pressure pump 2 based on embodiment of this invention.

Embodiments of the present invention will be described below with appropriate reference to the drawings. Note that the members, arrangement, etc. described below do not limit the present invention, and can be variously modified within the scope of the spirit of the present invention. Further, in each figure, the same reference numerals indicate the same elements, and the description thereof will be omitted as appropriate.

FIG. 1 shows the overall configuration of a fuel injection control device according to an embodiment of the present invention. A fuel injection control device according to an embodiment of the present invention is a pressure accumulation type fuel injection control device 10. The pressure accumulation type fuel injection control device 10 is a device for injecting fuel into a cylinder of an internal combustion engine (not shown). The pressure accumulation type fuel injection control device 10 includes a fuel injection valve 9 that supplies fuel to an internal combustion engine, a common rail 8 to which the fuel injection valve 9 is connected, and a high-pressure pump 7 that pumps pressurized high-pressure fuel to the common rail 8. , an electric low-pressure pump 2 that supplies fuel from the fuel tank 1 to the high-pressure pump 7, and a fuel filter 3 provided between the low-pressure pump 2 and the high-pressure pump 7 to perform rail pressure control, injection control, etc. An electronic control unit 50 is provided.

The high-pressure pump 7 is driven by the driving force of an internal combustion engine, and a camshaft 17 to which a cam 18 is fixed is connected to the crankshaft of the internal combustion engine. This high-pressure pump 7 supplies low-pressure fuel to the pressurizing chamber 12 via the fuel intake valve 27 when the plunger 29 descends, and when the plunger 29 is pushed up by the rotation of the cam 18, the low-pressure fuel is supplied to the pressurizing chamber 12. The fuel in the common rail 8 is pressurized, and the high-pressure fuel is pumped to the common rail 8 via the fuel discharge valve 28.

Note that the high-pressure pump 7 included in the pressure accumulation type fuel injection control device 10 of this embodiment is configured with three sets of plungers 29 and pressurizing chambers 12; The number is not particularly limited.

The high-pressure pump 7 also includes a flow control valve 19 . The flow rate control valve 19 is arranged in the middle of the fuel passage 31 that connects the low pressure pump 2 and the pressurizing chamber 12 of the high pressure pump 7, and is used to adjust the flow rate of low pressure fuel supplied to the pressurizing chamber 12. It is equipped. The flow rate control valve 19 is an electromagnetic proportional control valve whose energization is controlled by an electronic control unit 50 and whose fuel passage area changes proportionally depending on the current value. That is, by controlling the current value supplied to the flow control valve 19, the flow rate of fuel supplied to the pressurizing chamber 12 is adjusted.

The high-pressure pump 7 also includes a zero delivery throttle 16 between the flow rate control valve 19 and the pressurizing chamber 12. In the pressure accumulation type fuel injection control device 10 according to the present embodiment, a small amount of fuel passes through the flow rate control valve 19 even when the pumping amount of the high pressure pump 7 is zero. The zero delivery throttle 16 discharges this small amount of fuel to the outside of the high pressure pump 7.

Furthermore, the high-pressure pump 7 is provided with an overflow valve 15 in order to keep the pressure of the fuel flowing into the high-pressure pump 7 constant. The overflow valve 15 is arranged in an oil passage branching from a portion of the fuel passage 31 upstream of the flow control valve 19. The overflow valve 15 includes an orifice 13 and a mechanical valve 14 that opens when the fuel pressure exceeds the set force of the spring.

The fuel that has passed through the orifice 13 flows into the cam chamber that accommodates the cam 18 and camshaft 17, and is used to cool and lubricate the cam 18, camshaft 17, and other members around the cam, and then flows into the return passage 37 of the high-pressure pump 7. The fuel is discharged from the tank 1 to the fuel tank 1.

A part of the fuel that has passed through the valve 14 flows into the cam chamber together with the fuel that has passed through the orifice 13. It is discharged into the fuel tank 1 through the return passage 37 of the pump 7.

Note that while the pressure accumulation type fuel injection control device 10 is in operation, the discharge amount of the low pressure pump 2 is set so that fuel always passes through the overflow valve 15. Also, when the high-pressure pump 7 pumps fuel, fuel is discharged from the zero delivery throttle 16, but the amount is very small compared to the fuel that enters the pressurizing chamber of the high-pressure pump 7.

From the above, the fuel discharged from the low pressure pump 2 (denoted as A in FIG. 1) is distributed as follows. The fuel supplied from the low pressure pump 2 to the high pressure pump 7 is divided into a portion that passes through the flow control valve 19 and a portion that flows into the overflow valve 15. A portion of the fuel that has flowed into the overflow valve 15 flows into the cam chamber (denoted as B in FIG. 1), and the rest is discharged to the outside (denoted as C in FIG. 1).

Most of the fuel that has passed through the flow rate control valve 19 flows into the pressurizing chamber 12, while a portion of the fuel passes through the zero delivery throttle 16 (denoted as D in FIG. 1) and is then discharged to the outside. Most of the fuel that has flowed into the pressurizing chamber 12 is fed under pressure to the common rail 8 (denoted as F in FIG. 1), and a portion enters the cam chamber through the sliding part around the plunger 29 (denoted as E in FIG. 1). . The fuel that has entered the cam chamber from the pressurizing chamber 12 is used together with the fuel that has entered the cam chamber via the overflow valve 15 to cool and lubricate the area around the cam, and then flows from the return passage 37 of the high-pressure pump 7 to the fuel tank 1. It is discharged.

From the above, for the fuel (A) supplied from the low pressure pump 2 to the high pressure pump 7,
A=B+C+D+E+F
The relationship holds true.

The common rail 8 includes a rail pressure sensor 25 and a pressure control valve 23. The rail pressure sensor 25 detects the fuel pressure (rail pressure) within the common rail 8 and notifies the electronic control unit 50 of the detected fuel pressure (rail pressure). The rail pressure detected by the rail pressure sensor 25 is used for rail pressure control executed by the electronic control unit 50.

Further, the pressure control valve 23 is for discharging the high pressure fuel in the common rail 8 to the low pressure side, and the discharged fuel is returned to the fuel tank 1 via the return passage 38. . The pressure control valve 23 is an electromagnetic proportional control valve whose energization is controlled by an electronic control unit 50 and whose opening pressure changes proportionally in accordance with the current value. That is, by controlling the current value supplied to the pressure control valve 23, the maintainable rail pressure is adjusted. Note that 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 9 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. In the fuel injection valve 9, the injection hole is closed by applying back pressure to the rear end side of the nozzle needle, and the injection hole is opened by releasing the applied back pressure. As the back pressure control means for the fuel injection valve 9, an electrostrictive actuator equipped with a piezo element or an electromagnetic solenoid actuator is used. Further, in the fuel injection valve 9, the back pressure fuel used for injection control is returned to the fuel tank 1 via the return passage 39.

The electronic control unit 50 is mainly composed of a microcomputer with a known configuration, and has storage elements such as RAM and ROM, and has a drive circuit for driving the fuel injection valve 9, a flow control valve 19, and a pressure control valve 23. Equipped with an energizing circuit for energizing. In addition to inputting the detection signal of the rail pressure sensor 25, the electronic control unit 50 also receives various detection signals such as the rotational speed of the internal combustion engine, the accelerator opening, and the fuel temperature. It is intended to be input for control.

Next, the low pressure pump 2 according to this embodiment will be explained. The low-pressure pump 2 according to the present invention is of a type in which the applied voltage value is not adjusted and the discharge amount is not adjusted. Further, in FIG. 1, the low-pressure pump 2 is arranged inside the fuel tank 1, but it may be arranged outside the fuel tank 1.

FIG. 2 is a diagram for explaining the characteristics of the low pressure pump 2. As shown in FIG. In FIG. 2, the vertical axis is the fuel discharge amount per unit time (l/h) of the low-pressure pump 2, and the horizontal axis is the fuel pressure (Pa) on the downstream side of the low-pressure pump 2. In other words, the low-pressure pump 2 and the fuel filter The fuel pressure is between 3 and 3. In the following description, the fuel discharge amount (l/h) per unit time of the low-pressure pump 2 may be simply referred to as "the discharge amount of the low-pressure pump 2."

In FIG. 2, the broken line indicates the minimum discharge amount S (l/h) required by the pressure accumulation type fuel injection control device 10. The discharge amount S(l/h) is determined by the specifications of the pressure accumulation type fuel injection control device 10 and the specifications of the internal combustion engine in which the pressure accumulation type fuel injection control device 10 is installed. That is, the discharge amount of the low pressure pump 2 needs to exceed S(l/h).

The solid line, one-dot chain line, and two-dot chain line in FIG. 2 represent the relationship between the discharge amount of the low-pressure pump 2 and the fuel pressure downstream of the low-pressure pump 2, that is, between the low-pressure pump 2 and the fuel filter 3, under different conditions. shows. The solid line indicates the case where the voltage applied to the low pressure pump 2 is 14V and the fuel temperature is 40°C. The dashed line indicates the case where the voltage applied to the low pressure pump 2 is 13V and the fuel temperature is 40°C. The two-dot chain line indicates the case where the voltage applied to the low pressure pump 2 is 13V and the fuel temperature is 80°C.

In FIG. 2, the solid line, the one-dot chain line, and the two-dot chain line all indicate the characteristic that the fuel discharge amount decreases as the pressure on the downstream side of the low-pressure pump 2 increases. This is due to the following reasons. When the fuel filter 3 provided downstream of the low-pressure pump 2 deteriorates, that is, when the amount of foreign matter trapped in the fuel increases and the flow of fuel in the fuel filter 3 deteriorates, the low-pressure pump 2 and the fuel The fuel pressure across the filter 3 increases and the resistance to the fuel delivery of the low pressure pump 2 increases. Since the output of the low-pressure pump 2 cannot be adjusted, when the resistance increases, the discharge amount decreases.

Therefore, under conditions where the voltage applied to the low pressure pump 2 is 14 V and the fuel temperature is 40° C., the characteristics of the low pressure pump 2 change along the solid line in FIG. 2 depending on the degree of deterioration of the fuel filter 3. Moreover, the dashed line in FIG. 2 shows a state where the voltage applied to the low pressure pump 2 has decreased from 14V to 13V due to deterioration of the battery or alternator, compared to the solid line. When the applied voltage decreases, the discharge amount of the low-pressure pump 2 decreases, so the dashed-dotted line is located at a position offset downward from the solid line. Therefore, under conditions where the voltage applied to the low pressure pump 2 is 13 V and the fuel temperature is 40° C., the characteristics of the low pressure pump 2 change on the dashed line in FIG. 2 depending on the degree of deterioration of the fuel filter 3.

The two-dot chain line in FIG. 2 shows a state in which the fuel temperature has increased from 40°C to 80°C depending on the operating conditions, compared to the one-dot chain line. When the fuel temperature rises, the viscosity of the fuel decreases, and the pumping efficiency of the low-pressure pump 2 decreases, so the pumping amount of the low-pressure pump 2 decreases, and the two-dot chain line is offset downward from the one-dot chain line. It will be located at the location. Therefore, under conditions where the voltage applied to the low pressure pump 2 is 13 V and the fuel temperature is 80° C., the characteristics of the low pressure pump 2 change along the two-dot chain line in FIG. 2 depending on the degree of deterioration of the fuel filter 3.

Under the conditions indicated by the two-dot chain line in FIG. 2, point a1 shows the characteristics of the low-pressure pump 2 when the fuel filter 3 is new. When the fuel filter 3 deteriorates, the characteristics of the low-pressure pump 2 move toward the lower right on the two-dot chain line in FIG. 2, and eventually reach point a2. During this process, the characteristics of the low-pressure pump 2 fall below the minimum discharge amount S(l/h) required by the pressure accumulation type fuel injection control device 10. According to the present invention, a state in which the discharge amount of the low-pressure pump 2 falls below S(l/h) can be detected at an early stage.

FIG. 3 is a block diagram showing the configuration of a portion of the electronic control unit 50 constituting the pressure accumulation type fuel injection control device 10 according to the present invention, which is related to the implementation of the present invention. The electronic control unit 50 includes a flow rate control valve control section 500, a discharge amount calculation section 510, a discharge amount decrease calculation section 520, an actual discharge amount calculation section 530, a required discharge amount calculation section 540, and a determination section 550. , a processing section 560.

The flow rate control valve control unit 500 adjusts the amount of fuel pumped by the high pressure pump 7 by controlling the flow rate control valve 19, and performs feedback control so that the fuel pressure (rail pressure) inside the common rail 8 reaches a target value. This control has been implemented conventionally.

The discharge amount calculation unit 510 calculates the discharge amount (l/h) of the low pressure pump 2 from the fuel temperature and the voltage value applied to the low pressure pump 2. Although the fuel temperature is generally measured near the fuel inlet of the high-pressure pump 7, it may be measured at other locations. The voltage value applied to the low pressure pump 2 is the output voltage of the battery or alternator, is measured at an appropriate location, and is used in various parts in controlling the internal combustion engine, so it can be reused. The relationship among the fuel temperature, the voltage value applied to the low-pressure pump 2, and the discharge amount of the low-pressure pump 2 is grasped in advance at the development stage of the pressure accumulation type fuel injection control device 10, and is stored in an appropriate area of the electronic control unit 50. It is preserved. The discharge amount calculation unit 510 calculates the discharge amount of the low pressure pump 2 using the data.

The discharge amount decrease calculation unit 520 calculates the decrease (l/h) in the discharge amount of the low pressure pump 2 due to deterioration of the fuel filter 3. When the pressure accumulation type fuel injection control device 10 is installed in the internal combustion engine of an automobile, the discharge amount reduction calculation unit 520 calculates the current fuel temperature and the operating time of the internal combustion engine since the fuel filter 3 was new or the automobile's Based on the travel distance, a decrease in the discharge amount of the low pressure pump 2 is calculated. On the other hand, when the pressure accumulation type fuel injection control device 10 is installed in an internal combustion engine other than an automobile, such as an agricultural construction machine, the discharge amount reduction calculation unit 520 calculates the current fuel temperature and the internal combustion rate since the fuel filter 3 was new. The amount of decrease in the discharge amount of the low pressure pump 2 is calculated based on the operating time of the engine. As the fuel temperature, the same value as that used in the discharge amount calculation unit 510 is used.

Here, when the pressure accumulation type fuel injection control device 10 is installed in an internal combustion engine other than a car, such as an agricultural construction machine, the reason why the operating time of the internal combustion engine is used to calculate the decrease in the discharge amount of the low pressure pump 2. is as follows. In other words, in agricultural and construction machinery, etc., the internal combustion engine is operated for a long time when the vehicle is stopped, so it is better to use the operating time of the internal combustion engine than the mileage of the vehicle to more accurately determine the low-pressure pump 2. This is because the decrease in the discharge amount can be calculated.

When the discharge amount decrease calculating unit 520 uses the mileage of the vehicle in which the pressure accumulation type fuel injection control device 10 is installed when calculating the decrease in the discharge amount of the low-pressure pump 2, the following method is adopted. . First, when manufacturing a vehicle equipped with the pressure accumulation type fuel injection control device 10 or when replacing the fuel filter 3, information indicating that the fuel filter 3 is new is stored in an appropriate area of the electronic control unit 50. . Then, the mileage of the automobile after the fuel filter 3 is new is counted by the discharge amount reduction calculation unit 520, and the count value is stored in an appropriate area of the electronic control unit 50. The relationship between the mileage of the automobile and the decrease in the discharge amount of the low-pressure pump 2 is grasped in advance during the development stage of the pressure accumulation type fuel injection control device 10, and is stored in an appropriate area of the electronic control unit 50 in advance. The discharge amount decrease calculation unit 520 calculates the decrease in the discharge amount of the low-pressure pump 2 based on the driving time of the vehicle from this information.

When the discharge amount decrease calculation unit 520 calculates the decrease in the discharge amount of the low-pressure pump 2 using the operating time of the internal combustion engine in which the pressure accumulation type fuel injection control device 10 is installed, the following method is adopted. It will be done. First, when manufacturing an internal combustion engine equipped with the pressure accumulation type fuel injection control device 10 or when replacing the fuel filter 3, information indicating that the fuel filter 3 is new is stored in an appropriate area of the electronic control unit 50. Ru. Then, the operating time of the internal combustion engine after the fuel filter 3 is new is counted by the discharge amount reduction calculating section 520, and the count value is stored in an appropriate area of the electronic control unit 50. The relationship between the operating time of the internal combustion engine and the decrease in the discharge amount of the low-pressure pump 2 is grasped in advance at the development stage of the pressure accumulation type fuel injection control device 10, and is stored in an appropriate area of the electronic control unit 50 in advance. The discharge amount decrease calculation unit 520 calculates the decrease in the discharge amount of the low-pressure pump 2 based on the operating time of the internal combustion engine from this information.

The actual discharge amount calculation section 530 calculates the discharge amount (l/h) of the low pressure pump 2 calculated by the discharge amount calculation section 510 and the decrease in the discharge amount of the low pressure pump 2 calculated by the discharge amount decrease calculation section 520. (l/h), the actual discharge amount (l/h), which is the actual discharge amount of the low-pressure pump 2, is calculated.

The required discharge amount calculation unit 540 calculates the required discharge amount (l/h), which is the discharge amount of the low-pressure pump 2 required by the pressure accumulation type fuel injection control device 10, based on the operating state of the internal combustion engine. Specifically, the required discharge amount includes a first fuel amount (l/h) that is the amount of fuel that passes through the flow control valve 19 and a second fuel amount that is the amount of fuel that is discharged from the overflow valve 15. Calculated as the sum of amounts (l/h).

The amount of fuel passing through the flow control valve 19 is determined as follows. That is, the current value supplied to the flow control valve 19 is determined by the flow control valve control unit 500 during feedback control for setting the rail pressure to the target value. The relationship between the current value supplied to the flow control valve 19 and the amount of fuel passing through the flow control valve 19 can be known in advance from the specifications of the pressure accumulation type fuel injection control device 10, and the relationship is as follows. It is stored in an appropriate area of the electronic control unit 50. Therefore, the required discharge amount calculating section 540 can grasp the amount of fuel passing through the flow control valve 19 from the current value supplied to the flow control valve 19 determined by the flow control valve control section 500.

The amount of fuel (l/h) discharged from the overflow valve 15 is determined as follows. That is, the maximum value of the amount of fuel discharged from the overflow valve 15 is stored in an appropriate area of the electronic control unit 50, taking into account the individual variations of the low pressure pump 2, overflow valve 15, etc. This was determined in advance through tests and the like during the development stage of the pressure accumulation type fuel injection control device 10. The required discharge amount calculation unit 540 reads the maximum value from the electronic control unit 50.

The determination unit 550 compares the actual discharge rate of the low pressure pump 2 calculated by the actual discharge rate calculation unit 530 with the required discharge rate of the low pressure pump 2 calculated by the required discharge rate calculation unit 540, and determines the actual discharge rate. When the discharge amount is less than the required discharge amount, it is determined that the low pressure pump 2 is abnormal.

The processing unit 560 performs processing such as torque restriction when the determination unit 550 determines that the low-pressure pump 2 is abnormal (details will be described later).

FIG. 4 is a functional block diagram functionally representing abnormality detection processing of the low pressure pump 2 in the embodiment of the present invention. The process shown in FIG. 4 is repeated at predetermined intervals.

The discharge amount calculation unit 510 calculates the discharge amount of the low pressure pump 2 using the voltage value applied to the low pressure pump 2 and the fuel temperature as input values. The discharge amount does not include the influence of deterioration of the fuel filter 3.

The discharge amount decrease calculation unit 520 calculates the discharge amount decrease by inputting the operating time of the internal combustion engine or the mileage of the automobile and the fuel temperature after the fuel filter 3 is new.

The actual discharge amount calculation section 530 calculates the actual discharge amount of the low pressure pump 2 from the difference between the discharge amount of the low pressure pump 2 calculated by the discharge amount calculation section 510 and the discharge amount decrease calculated by the discharge amount decrease calculation section 520. Calculate the discharge amount. In FIG. 4, an addition symbol is used for the actual discharge amount calculation unit 530, but since the decrease in the discharge amount is processed as a negative number, it is actually a subtraction process.

The required discharge amount calculation unit 540 adds the amount of fuel passing through the flow rate control valve 19 and the maximum amount of fuel discharged from the overflow valve 15, which is calculated as a result of rail pressure feedback control. , the required discharge amount of the low pressure pump 2 is calculated.

The determination unit 550 compares the actual discharge rate of the low pressure pump 2 calculated by the actual discharge rate calculation unit 530 with the required discharge rate of the low pressure pump 2 calculated by the required discharge rate calculation unit 540, and determines the actual discharge rate. When the discharge amount is less than the required discharge amount, it is determined that the low pressure pump 2 is abnormal.

FIG. 5 is a subroutine flowchart showing the processing performed in the processing unit 560 after the determination unit 550 determines that the low-pressure pump 2 is abnormal. This subroutine flowchart is repeated at predetermined intervals along with the abnormality detection process of the low pressure pump 2 shown in FIG.

When the process is started, first in step S102, it is determined whether the determination unit 550 determines that the low pressure pump 2 is abnormal. If the determination is YES in step S102, the process advances to step S104, while if the determination is NO in step S102, the process in the processing unit 560 is deemed unnecessary and the process returns to the main routine (not shown).

Note that after the determination unit 550 determines that the low-pressure pump 2 is abnormal, the process does not immediately proceed to step S104, but after the low-pressure pump 2 is determined to be abnormal, a timer provided inside the electronic control unit 50 is started. Then, when the state in which the low pressure pump 2 is determined to be abnormal continues for a predetermined period of time, the process may proceed to step S104. The predetermined time at that time can be set in advance at the development stage of the pressure accumulation type fuel injection control device 10 and saved in an appropriate area of the electronic control unit 50.

In step S104, it is determined whether a second restriction process, which will be described later, is being executed. If the determination is NO in step S104, the process advances to step S106, while if the determination is YES in step S104, the subsequent processing is not performed and the process returns to the main routine (not shown).

In step S106, a first restriction process is executed. In the first limiting process, the processing unit 560 limits the torque generated by the internal combustion engine to a first predetermined value or less. Since the relationship between the fuel injection amount and the generated torque under each operating condition is known in advance, the processing unit 560 actually limits the torque by limiting the fuel injection amount.

In subsequent step S108, it is determined whether a predetermined time period has elapsed since the first restriction process was executed. If it is determined YES in step S108, the process proceeds to step S110, while if it is determined NO in step S108, the first restriction process is continued until a predetermined time has elapsed. Note that the predetermined time in this step is set in advance during the development stage of the pressure accumulation type fuel injection control device 10, and is stored in an appropriate area of the electronic control unit 50.

In step S110, the actual ejection amount calculated by the actual ejection amount calculation section 530 is calculated by adding a predetermined threshold value to the required ejection amount in the first restriction process calculated by the required ejection amount calculation section 540. It is determined whether or not it exceeds. The predetermined threshold value in this step is set in advance during the development stage of the pressure accumulation type fuel injection control device 10, and is stored in an appropriate area of the electronic control unit 50. If the determination is YES in step S110, the process proceeds to step S112, while if the determination is NO in step S110, the process proceeds to step S114.

The process in step S110 determines whether the abnormality determination of the low pressure pump 2 is temporary. The case where the abnormality determination of the low pressure pump 2 is temporary means, for example, when the output value of the sensor temporarily becomes an abnormal value due to the influence of noise, or when the low pressure pump 2 is determined to be abnormal for some reason. Various factors can be considered, such as temporary changes in the power supply.

The reason why the condition for determining YES in step S110 is not only that the actual ejection amount exceeds the required ejection amount but also that the difference between the two exceeds a threshold is as follows. This is due to In the first restriction process, since the fuel injection amount is restricted, the required discharge amount is also calculated to be small. Therefore, the actual discharge amount is likely to exceed the required discharge amount, and this condition alone is insufficient to determine whether or not the abnormality of the low-pressure pump 2 is temporary.

In step S112, the first restriction process is stopped and the operation of the internal combustion engine is returned to normal operation. This is because it was determined in S110 that the abnormality of the low pressure pump 2 was determined to be temporary.

In step S114, a second restriction process is started. In the second restriction process, the processing unit 560 further reduces the fuel injection amount than in the first restriction process, and increases the generated torque of the internal combustion engine to a second predetermined value that is even smaller than the first predetermined value in the first restriction process. Limited to: Further, the processing unit 560 performs processing to notify the driver of an abnormality using an error lamp or the like. This is a process performed because it has been determined that the abnormality determination of the low pressure pump 2 is not temporary due to the NO determination in step S110.

As described above, according to the present invention, abnormality determination of the low pressure pump 2 can be performed without adding a new device. In addition, it is confirmed whether the abnormality determination of the low pressure pump 2 is temporary or not, and after it is confirmed that it is not temporary, it is possible to confirm the abnormality and execute processing corresponding to the abnormality. Become.

1: Fuel tank, 2: Low pressure pump, 3: Fuel filter, 7: High pressure pump, 8: Common rail, 9: Fuel injection valve, 15: Overflow valve, 19, Flow rate control valve, 50: Electronic control unit, 500: Flow rate Control valve control section, 510: Discharge amount calculation section, 530: Actual discharge amount calculation section, 540: Required discharge amount calculation section, 550: Determination section, 560: Processing section

Claims (9)

a fuel injection valve that supplies fuel to an internal combustion engine;
a common rail to which the fuel injection valve is connected;
a high-pressure pump that pumps pressurized high-pressure fuel to the common rail;
an electric low pressure pump that supplies fuel from the fuel tank to the high pressure pump;
a flow control valve that is included in the high-pressure pump and adjusts the amount of fuel pumped by the high-pressure pump;
an electronic control unit;
In a fuel injection control device equipped with
The electronic control unit includes:
a flow rate control valve control unit that performs feedback control so that the fuel pressure in the common rail reaches a target value by controlling the flow rate control valve;
a discharge amount calculation unit that calculates a discharge amount of the low pressure pump from a fuel temperature and a voltage value applied to the low pressure pump;
a discharge amount decrease calculation unit that calculates a decrease in the discharge amount of the low-pressure pump due to deterioration of the fuel filter;
The actual discharge amount, which is the actual discharge amount of the low-pressure pump, is calculated from the discharge amount of the low-pressure pump calculated by the discharge amount calculation section and the decrease in the discharge amount of the low-pressure pump calculated by the discharge amount decrease calculation section. an actual discharge amount calculation unit that calculates the amount;
a required discharge amount calculation unit that calculates a required discharge amount that is a discharge amount of the low-pressure pump that is required by the fuel injection control device;
a determination unit that determines that the low-pressure pump is abnormal when the actual discharge amount is less than the required discharge amount;
including fuel injection control equipment. 1 . The discharge amount decrease calculation unit calculates the decrease in the discharge amount of the low-pressure pump due to deterioration of the fuel filter based on the operating time of the internal combustion engine since the fuel filter was new. The fuel injection control device described in . The discharge amount decrease calculation unit calculates a decrease in the discharge amount of the low-pressure pump due to deterioration of the fuel filter based on a mileage of the vehicle equipped with the internal combustion engine since the fuel filter was new. The fuel injection control device according to claim 1. The high-pressure pump includes an overflow valve that maintains a constant pressure of the fuel supplied to the high-pressure pump by discharging a portion of the fuel supplied from the low-pressure pump to the outside,
The required discharge amount is calculated by the flow control valve control unit and includes a first fuel amount that is the amount of fuel that should pass through the flow control valve, and a second fuel amount that is the amount of fuel that is discharged from the overflow valve. The fuel injection control device according to claim 1, wherein the fuel injection control device includes a fuel amount of . The fuel injection control device according to claim 4, wherein the second fuel amount is a predetermined fixed value. The electronic control unit further includes a processing section that executes a first limiting process that limits the torque generated by the internal combustion engine to a first predetermined value or less when the determining section determines that the low-pressure pump is abnormal. The fuel injection control device according to claim 1. The processing unit executes the first restriction process if the actual ejection amount exceeds the sum of the required ejection amount in the first restriction process and a predetermined threshold after executing the first restriction process. The fuel injection control device according to claim 6, wherein the fuel injection control device stops. After execution of the first restriction process, the processing unit is configured to reduce the generated torque of the internal combustion engine if the actual discharge amount is equal to or less than the sum of the required discharge amount in the first restriction process and a predetermined threshold value. 7. The fuel injection control device according to claim 6, wherein the fuel injection control device executes a second restriction process to limit the value to a second predetermined value or less that is lower than the first predetermined value. a fuel injection valve that supplies fuel to an internal combustion engine;
a common rail to which the fuel injection valve is connected;
a high-pressure pump that pumps pressurized high-pressure fuel to the common rail;
an electric low pressure pump that supplies fuel from the fuel tank to the high pressure pump;
a flow control valve that is included in the high-pressure pump and adjusts the amount of fuel pumped by the high-pressure pump;
an electronic control unit;
A method for controlling a fuel injection control device comprising:
a flow rate control step in which a flow rate control valve control unit performs feedback control by controlling the flow rate control valve so that the fuel pressure in the common rail reaches a target value;
a discharge amount calculation step in which a discharge amount calculation unit calculates a discharge amount of the low pressure pump from a fuel temperature and a voltage value applied to the low pressure pump;
a discharge amount decrease calculation step in which the discharge amount decrease calculation unit calculates a decrease in the discharge amount of the low-pressure pump due to deterioration of the fuel filter;
An actual discharge amount calculation section calculates the actual output of the low pressure pump from the discharge amount of the low pressure pump calculated by the discharge amount calculation section and the decrease in the discharge amount of the low pressure pump calculated by the discharge amount decrease calculation section. an actual discharge amount calculation step of calculating an actual discharge amount that is a discharge amount of
a necessary discharge amount calculation step in which the required discharge amount calculation unit calculates a required discharge amount that is a discharge amount of the low-pressure pump required by the fuel injection control device;
a determination step in which the determination unit determines that the low-pressure pump is abnormal when the actual discharge amount is less than the required discharge amount;
A control method for a fuel injection control device, including:

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