JP2003083140A - Fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem wherein injection accuracy becomes remarkably high according to the strengthening of the regulation of exhaust gas, but a possibility that high injection accuracy can not be maintained due to a change of injection quantity with a secular change exists, even if performing a fine adjustment before shipment. SOLUTION: Minute injection quantity QS so as not to affect engine torque is injected when forming a fuel cut condition, deviation quantity ΔQ of injection is determined from a difference of an actual measured value O2R and a target value O2T of an exhaust sensor, an injection correction value ΣΔQ is determined based on the value ΔQ, and the value ΣΔQ is stored in a memory. The injection correction value ΣΔQ is updated as occasion demands when cutting fuel during traveling of a vehicle. Each fuel injection quantity QFIN is determined by using the injection correction value ΣΔQ stored in the memory at the time of fuel injection, and high injection accuracy is maintained for a long period, even if a secular change is generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device, and more particularly to a fuel injection device which automatically corrects a deviation of an injection amount due to a change with time or the like.

[0002]

2. Description of the Related Art In recent years, with the tightening of regulations on exhaust gas, the required accuracy of the injection amount required at the time of fuel injection has been remarkably increased. As a specific example, in recent diesel engines, demands for pilot injection, multi-stage injection, and the like are increasing along with the tightening of exhaust gas regulations, and the required accuracy level of the injection amount is 5 mm ³ / From about st (st = 1 stroke), it is 1 mm ³ / st.

[0003]

In order to obtain high injection accuracy, it is possible to make fine adjustments to the fuel injection device and the like before shipping. However, even if fine adjustment is performed, the injection amount may change due to a change over time, and high injection accuracy may not be maintained.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object thereof is to provide a fuel injection device capable of maintaining high injection accuracy for a long period of time.

[0005]

[Means for Solving the Problems] [Means for Claim 1] In a fuel injection device adopting the means for claim 1, the fuel injection is performed at the transition to the fuel injection cut, during the fuel injection cut, or from the fuel injection cut state. At the time of transition to, a predetermined minute injection amount (injection amount that does not affect the engine torque) is injected. The concentration of the substance contained in the exhaust gas generated during the minute fuel injection is detected by the exhaust sensor, and the measured value and the target value are compared. An injection correction value is obtained from this comparison value and the injection correction value is stored. Then, during normal operation, by determining the fuel injection amount using the stored injection correction value, it is possible to maintain high injection accuracy even if there is a change over time in the movable part of the fuel injection system or the like. That is,
Even if there is a change over time, high injection accuracy can be maintained for a long time by correcting the injection amount.

[Means for Claim 2] The means for claim 2 may be adopted to correct the minute injection amount by the injection correction value.

[Means for Claim 3] The means for claim 3 may be adopted to obtain an injection correction value for each cylinder and store the injection correction value for each cylinder.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described with reference to two examples and modifications. [First Embodiment] A first embodiment will be described with reference to FIGS. The fuel injection device to which the present invention is applied is applied to a common rail fuel injection device, and an example of this fuel injection device will be described with reference to FIG.

The fuel injection device is for injecting fuel from an injector 2 attached to each cylinder of a diesel engine 1. Each injector 2 has a common rail 3
Solenoid valve for controlling the injection and injection stop by opening and closing the high-pressure fuel supplied to the combustion chamber (for example, a piezo valve that uses a piezo stack with multiple piezo elements stacked as an actuator, or a coil is generated) It is equipped with a solenoid valve that drives the armature by magnetic force.
The solenoid valve is opened / closed by a signal given from an engine control unit (corresponding to a control device; hereinafter, ECU) 4.

The fuel in the fuel tank 5 is pressure-fed to the common rail 3 by the operation of the high-pressure supply pump 6, and the high-pressure fuel is stored inside the common rail 3. Further, the fuel supplied from the common rail 3 to the injector 2 is used not only for injection into the combustion chamber but also as control hydraulic pressure for the injector 2, and is supplied to the fuel tank 5 from the injector 2 via the low pressure drain line 7. It is supposed to be refluxed.

A pressure sensor 8 for detecting the fuel pressure is attached to the common rail 3. ECU4
Controls the opening of the metering valve 9 based on the output of the pressure sensor 8 to adjust the amount of fuel to be pumped to the common rail 3 to maintain the internal pressure of the common rail 3 at an appropriate pressure. Further, the common rail 3 is provided with a pressure limiter 10 for returning the fuel, which has risen above a predetermined pressure, to the fuel tank 5 to prevent the pressure abnormality of the common rail 3 from occurring.

The ECU 4 controls the injection timing and the injection amount of fuel by controlling the energization of the solenoid valve of the injector 2. In order to obtain an information signal for calculation (a signal for detecting the operating state of the engine 1), the ECU 4 has an accelerator sensor 11 for detecting the accelerator opening ACCP and a rotational speed capable of detecting the engine rotational speed NE. A sensor 12, a water temperature sensor 13 that detects the cooling water temperature TW of the engine 1, an exhaust sensor 14 that detects the oxygen concentration contained in the exhaust gas of the engine 1, and other sensors are connected. The ECU 4 is well known and includes a CPU, a RAM, a ROM, an AD converter, not shown.
It consists of an input port and an output port.

The fuel injection device may perform only "normal injection" by controlling energization of the solenoid valve of the injector 2, or "normal injection" or "pilot injection" depending on the operating state of the engine 1. May be switched and implemented. The "pilot injection" is intended to reduce the combustion noise in the region excluding the high load region, and is to inject the "normal injection" separately.

In the ROM mounted in the ECU 4,
A program for controlling the solenoid valve of the injector 2 to control the fuel injection amount and injection timing is stored.
A calculation program of the opening / closing command value of the solenoid valve of the injector 2 which is calculated by the accelerator opening ACCP and the engine rotation speed NE and is corrected by the cooling water temperature TW of the engine 1 is stored in advance. In the following examples,
In order to facilitate understanding of the embodiment according to the present invention, the correction by the cooling water temperature TW of the engine 1 and the correction by the individual difference of the solenoid valve of the injector 2 will be omitted.

In the ROM mounted in the ECU 4,
A function of a correction unit that learns and corrects, for each cylinder, a deviation in the injection amount of each cylinder due to a change with time of the injector 2 or the like is programmed in advance. This program, for example, at the time of transition to fuel injection cut (first learning state described later),
A predetermined minute injection amount QS (injection amount that does not affect the engine torque) is injected into the cylinder to be corrected, and the exhaust gas sensor 14 detects the oxygen concentration contained in the exhaust gas generated during this minute fuel injection. The measured value O ² R of the exhaust sensor 14 and the target value O ² T corresponding to the injection amount at that time are compared, the injection correction value ΣΔQ in the cylinder to be corrected is obtained from the difference ΔO ² , and the injection correction value ΣΔQ to ECU4
The data is stored in a backup RAM (for example, a non-volatile memory) mounted inside. And the ECU
Reference numeral 4 is a fuel injection amount QFIN for each cylinder in consideration of the injection correction value ΣΔQ for each cylinder stored in the backup RAM.
Is determined, and the solenoid valve of the injector 2 is controlled to be opened / closed so that the fuel injection amount QFIN is obtained.

The region where the ECU 4 injects a small amount of fuel to obtain the injection correction value ΣΔQ is shown as a learning state in FIG. As shown in FIG. 2, the learning state is a state in which the engine is unloaded, and is an area in which the engine torque is not affected even if a small amount of fuel is injected. The first learning state described above will be described with reference to FIG. The first learning state is when the engine load is no load and the injection amount command value is 0 or less. An example in which the second learning state in which the engine load is no load and the injection amount command value is larger than 0 is used will be described later in the second example.
An example will be described.

A specific time when the ECU 4 obtains the injection correction value ΣΔQ will be described with reference to FIG. 0% accelerator opening
Therefore, the fuel injection cut is performed when the engine speed NE decreases (that is, when the operating state detected by the operating state detecting means satisfies the predetermined condition for performing the fuel injection cut). This fuel injection cut is started, and the first
When in the learning state, the ECU 4 obtains the injection correction value ΣΔQ.

As shown in FIG. 4, the output of the exhaust sensor 14 produces an output according to the fuel injection amount. So E
CU4 is an actual measurement value O ² R of the exhaust sensor 14 (output value of oxygen concentration contained in exhaust gas generated at the time of minute fuel injection)
Is compared with a target value O ² T (a target output value that should be detected when an appropriate minute injection amount QS is injected), and the difference ΔO ^{2 is used} to find the difference in the injection amount due to the change over time. It is provided so as to obtain the injection correction value ΣΔQ from the amount ΔQ.

Next, an example of correction control by the correction means will be described.
This will be described with reference to the flowchart of FIG. Engine 1
If the control routine is entered during the operation of (IN) (IN), the parameters of the engine 1 are read in step 100. In step 101, the basic injection amount QB is calculated based on the engine speed NE and the accelerator opening ACCP read in step 100.

In step 102, it is judged whether or not the learning execution conditions such as the starting rotation speed NE and after warming up are satisfied by the flag f = 1. If the determination result of step 102 is NO (state where the learning execution condition is not satisfied), the process proceeds to the fuel injection step. In the fuel injection step, first, in step 103, the backup RA
The injection correction value ΣΔQ stored in M is taken out.

Next, at step 104, the final fuel injection amount QF is calculated using the basic injection amount QB and the injection correction value ΣΔQ.
Calculate IN. Specifically, at step 104, the correction coefficient f (N is obtained from the rotational speed NE and the basic injection amount QB.
E, QB) is reflected in the injection correction value ΣΔQ, and the basic fuel injection amount QB is corrected by that value to obtain the final fuel injection amount QFIN. Next, in step 105, the final fuel injection amount QFIN is set as an output value in the output stage, and then the process returns.

On the other hand, if the decision result in the step 102 is YES (the learning execution condition is satisfied), it is decided in the step 106 whether or not the exhaust sensor 14 is activated so that the exhaust gas can be detected. I do. If the result of this determination is NO, the routine proceeds to step 103, and if the result of this determination is YES, it is immediately after the fuel injection cut was made in step 107, and whether the operating state is within the range of the first learning state. Make a decision.

If the determination result in step 107 is NO, the process proceeds to step 103, and if the determination result is YES, the count value of the counter K that is incremented each time the injection correction value ΣΔQ of each cylinder is updated in step 108 is It is determined whether the number of cylinders of the engine 1 has been reached. That is, in the case of the 4-cylinder engine 1, it is determined whether or not the counter K = 4.

If the determination result in step 108 is YES, learning (checking / updating of the injection correction value ΣΔQ) for all cylinders has been completed, so learning is performed from the first cylinder when the conditions for next learning are satisfied. Step 10
At 9 and 110, the cylinder counter K is reset and the learning execution condition flag f is reset, and then the process proceeds to step 103.

If the determination result in step 108 is NO,
Implement learning of unlearned cylinders. First, step 111
At, the number of injections α of the minute fuel in the learning cylinder is determined. Next, at step 112, the minute injection amount QS stored in the ROM is taken out. Next, step 1
At 13, the injection correction value ΣΔQ stored in the backup RAM is taken out, and in this embodiment, the injection correction value ΣΔQ is added to the minute injection amount QS to obtain the corrected minute injection amount Q.
S'is obtained and output.

Next, at step 114, the number of injections of the corrected minute injection amount QS 'is counted up (n = n + 1). Next, at step 115, the actually measured value O ² R of the exhaust sensor 14 is fetched. Next, at step 116, a deviation value ΔO ² between the actual measurement value O ² R of the exhaust sensor 14 and the target value O ² T is calculated. Next, in step 117, the deviation amount ΔQ of injection is obtained using the deviation value ΔO ² and a predetermined coefficient.

Next, at step 118, it is judged if the injection deviation amount ΔQ is smaller than a preset predetermined value β. If the determination result is YES, it is determined that the learning of the predetermined cylinder is completed, and the cylinder to be learned is updated in step 119 (K = K + 1), and the injection correction value ΣΔQ is stored in the backup RAM in step 120. Then, in step 121, the counter n of the number of injection executions of the corrected minute injection amount QS 'is reset (n = 0), and then the process proceeds to step 103.

If the result of the determination in step 118 is NO,
This is a case where the injection amount deviates by a predetermined amount or more due to a change over time, and the injection correction value ΣΔQ is newly updated. Specifically, in step 122, it is determined whether the output number n of the minute injection has reached the predetermined injection number α. If the determination result is YES, the process proceeds to step 121, and if the determination result is NO, in step 123, the injection correction value Σ
The injection deviation amount ΔQ is added to ΔQ to update a new injection correction value ΣΔQ. Then, the process returns to step 113, and it is checked whether or not the updated injection correction value ΣΔQ is proper.

An example of updating the injection correction value ΣΔQ will be described with reference to the time chart of FIG. When the fuel injection cut condition is satisfied, conventionally, fuel is not injected as shown by the broken line in the figure, but in the first embodiment, when the operating state falls within the range of the first learning state when the fuel injection is cut, As shown by the solid line in FIG.
S fuel is injected independently. When the measured value O ² R of the exhaust sensor 14 at this time is a solid line'in the figure, '
From the difference from the target value O ² T shown by
Calculate (learning correction amount). Then, the injection correction value ΣΔQ is obtained using the deviation amount ΔQ of this injection, and the backup R
Remember in AM.

[Effects of First Embodiment] As described above, the fuel injection device according to the first embodiment affects the engine torque when the fuel injection cut is started and the first learning state is reached. The fuel injection amount QS is detected by injecting a minute injection amount QS that does not give a difference, and if there is a deviation, an injection correction value ΣΔQ for correcting the deviation is calculated from the deviation amount ΔQ. And stored in the backup RAM. Then, the fuel injection amount QFIN to be injected into each cylinder is determined using the injection correction value ΣΔQ for each cylinder stored in the backup RAM. For this reason, even if the moving parts such as the injector 2 change with time, high injection accuracy can be maintained for a long time. That is, even if the fuel injection system changes over time, the injection amount is corrected, so that high injection accuracy can be maintained for a long period of time.

Further, even if the engine 1 manufactured independently of the fuel injection device has a variation, when the engine 1 and the fuel injection system are finally combined, the variation is caused by the fuel injection device. Since the learning correction is performed, the engine 1 can be operated according to the target value. Therefore, it is possible to simplify the adjustment for eliminating the variation after combining both the engine 1 and the fuel injection system, and it is possible to reduce the cost.

[Second Embodiment] In the first embodiment, in the first learning state of the fuel injection cut, a small amount of fuel is injected to measure the deviation of the injection amount, and the injection correction value ΣΔQ is learned. However, in the second embodiment, injection is performed from the fuel injection cut state (no injection state) (non-fuel injection cut).
During the second learning state of shifting to, the injection correction value ΣΔQ for correcting the deviation of the injection quantity due to the change over time is measured by injecting the minute fuel and measuring the deviation quantity ΔQ of the injection.

An example of updating the injection correction value ΣΔQ in the second embodiment will be described with reference to FIG. At the time of transition from the fuel injection cut to the fuel injection state, conventionally, the fuel injection amount was gradually increased as shown by the broken line in the figure. In the range of the two learning states, as shown by the solid line in the figure, the fuel of the small injection amount QS is independently injected in a predetermined cylinder. When the measured value O ² R of the exhaust sensor 14 at this time is a solid line'in the figure, the injection deviation amount ΔQ (learning correction amount) is calculated from the difference from the target value O ² T shown by the dashed line'in the figure. Ask. Then, the ECU 4 performs the injection deviation amount ΔQ, as in the first embodiment.
The injection correction value ΣΔQ for correcting the deviation of the injection amount is calculated from the above, stored in the backup RAM, and the stored injection correction value ΣΔQ is used to correct the basic injection amount QB.

[Modification] In the above embodiment, an example in which a small amount of fuel is injected to obtain the injection correction value ΣΔQ at the time of transition to the fuel injection cut and at the transition from the fuel injection cut state to the fuel injection is shown. However, the engine 1
May be provided so as to obtain the injection correction value ΣΔQ by injecting a small amount of fuel by combining the above-described first embodiment and second embodiment with no load. In the above embodiment, an example in which the minute injection amount QS is corrected by the injection correction value ΣΔQ is shown, but the injection correction is made by a map or a calculation formula from the difference between the actual measurement value O ² R of the exhaust sensor 14 and the target value O ² T. The value ΣΔQ may be obtained.

In the above embodiment, the present invention is applied to the common rail type fuel injection device, but the distribution type fuel injection device, etc.
The present invention may be applied to other types of injection devices. In the above embodiment, the example in which the variation of the diesel engine 1 is corrected has been shown, but the present invention may be applied to the fuel injection device that corrects the variation of the gasoline engine.

[Brief description of drawings]

FIG. 1 is a flow chart for correcting a deviation in fuel injection caused by a change over time (first embodiment).

FIG. 2 is a graph for explaining a learning area (first
Example).

FIG. 3 is a time chart for explaining the operation (first
Example).

FIG. 4 is a graph showing output characteristics of an exhaust sensor (first example).

FIG. 5 is a schematic configuration diagram of a fuel injection device (first embodiment).

FIG. 6 is a time chart for explaining the operation (second)
Example).

[Explanation of symbols]

1 Engine 2 Injector 4 ECU (Control Unit) 11 Accelerator Sensor 12 Revolution Sensor 13 Water Temperature Sensor 14 Exhaust Sensor O ² R Measured Value O ² T Target Value ΣΔQ Injection Correction Value QFIN Fuel Injection Amount

Claims (3)

[Claims] 1. An operating state detecting means for detecting an operating state of an engine, a fuel injection amount being determined based on the operating state detected by the operating state detecting means, and an operating state detected by the operating state detecting means A control device that performs a fuel injection cut when a predetermined condition is satisfied, the operating state detection means includes an exhaust sensor that generates an output according to the concentration of a substance contained in the exhaust gas of the engine, the control The device injects a predetermined minute injection amount during transition to fuel injection cut, during fuel injection cut, or during transition from fuel injection cut state to fuel injection, and is included in the exhaust gas generated during this minute fuel injection. The concentration of the substance is detected by the exhaust sensor, the measured value and the target value are compared to obtain and store an injection correction value, and the stored injection correction value is used to store the fuel. A fuel injection device comprising a correction means for determining an injection amount. 2. The fuel injection device according to claim 1, wherein the correction means corrects the minute injection amount by the injection correction value. 3. The fuel injection device according to claim 1 or 2, wherein the correction means obtains and stores the injection correction value for each cylinder.