JPH10252529A - Fuel injection timing control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and surely correct the fuel injection timing corresponding to a pressure and a temperature, relating to the fuel injection timing control device suited for use in a Diesel engine. SOLUTION: This device is constituted so as to have an intake pressure detection means 14 detecting an intake pressure of an engine 1, intake temperature detection means 16 detecting an intake temperature, engine speed detection means detecting a rotational speed of the engine 1, and a control means 12 advancing the fuel injection timing based on detected information from the intake pressure detection means 14, intake temperature detection means 16 and the engine speed detection means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection timing control device suitable for use in a diesel engine.

[0002]

2. Description of the Related Art In general, in a diesel engine in which fuel is ignited spontaneously by the heat of pressurized air, the combustion state of the fuel is determined by ambient atmospheric conditions, particularly atmospheric pressure (intake pressure) and atmospheric temperature (intake air pressure). Temperature). Specifically, the fuel injected into the combustion chamber starts burning with a delay of a predetermined time τ, and the predetermined time (ignition delay time) τ is greatly affected by the pressure and the temperature.

[0003] When the ignition delay time τ becomes large, it is conceivable that the output torque is lowered or white smoke is discharged. Further, if the ignition delay time τ is further increased, the engine may be misfired.
For this reason, various techniques for preventing misfire of a diesel engine due to a change in atmospheric conditions have been conventionally proposed and developed.

For example, in a fuel injection device capable of changing the fuel injection timing, a pressure sensor and a fuel injection timing correction map storing a fuel injection timing correction amount corresponding to atmospheric pressure are provided. A technique is known in which the fuel injection timing is changed according to the atmospheric pressure obtained by a pressure sensor. Further, similarly to the above, a temperature sensor and a fuel injection timing correction map for setting a correction amount of the fuel injection timing according to the temperature are provided, and the fuel injection timing is set when the temperature is low or the engine coolant temperature is low. A technique for changing the fuel injection timing by using a correction map is also known.

[0005] Japanese Patent Publication No. 3-26626 discloses that
There is disclosed a technique in which the fuel injection timing is corrected according to the intake pressure of the engine.

[0006]

However, in such a conventional technique, in order to simultaneously perform pressure correction and temperature correction, both a pressure correction map and a temperature correction map are provided. Therefore, the fuel injection timing control becomes complicated, and it is difficult to control the fuel injection timing so that the fuel injection timing is always optimal.
In particular, when the engine is running at a high altitude (that is, a place where the atmospheric pressure is low) and the engine is cold, it is difficult to control the fuel injection timing to the optimum.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and enables the fuel injection timing of a diesel engine to be easily and reliably corrected according to the pressure and the temperature so that the optimum fuel injection timing is always obtained. Control,
It is an object to provide a fuel injection timing control device.

[0008]

According to a first aspect of the present invention, there is provided a fuel injection timing control apparatus for detecting an intake pressure of an engine, an intake pressure detecting means for detecting an intake air temperature. Control for advancing the fuel injection timing based on detection information from the engine speed detecting means for detecting the engine speed, the intake pressure detecting means, the intake temperature detecting means, and the engine speed detecting means. Means,
It is characterized by having.

According to a second aspect of the present invention, in addition to the configuration of the first aspect, the control means is detected by the intake pressure detecting means and the intake temperature detecting means. Ignition delay time calculating means for calculating an ignition delay time from injection of fuel to ignition based on the intake pressure and intake air temperature, and a pressure propagation time from a fuel injection pump to a fuel injection valve of the engine. Pressure propagation time calculation means, the engine speed detected by the engine speed detection means, the ignition delay time calculated by the ignition delay time calculation means, and the pressure propagation time calculated by the pressure propagation time calculation means An ignition delay crank angle calculating means for calculating an ignition delay crank angle from the engine rotation speed and an engine load detected by the engine speed detection means. Fuel injection timing setting means for setting the fuel injection timing based on the engine load detected by the stage, and the fuel injection timing set by the fuel injection timing setting means and the ignition calculated by the ignition delay crank angle calculation means If the sum of the delay crank angle is larger than a predetermined value, the actual fuel injection timing is advanced up to the amount obtained by subtracting the predetermined value from the sum of the fuel injection timing and the ignition delay crank angle. Correction means.

According to a third aspect of the present invention, there is provided a fuel injection timing control apparatus according to the second aspect, wherein the predetermined value is equal to an engine speed detected by the engine speed detecting means. , And is set based on the engine load detected by the engine load detecting means.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a fuel injection timing control device according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic overall configuration diagram of an engine to which the present device is applied. Reference numeral 1 denotes a diesel engine that ignites fuel by compressed air, 2 denotes an intake passage, and 3 denotes an exhaust passage.

Further, the engine 1 is provided with a turbocharger 4 and an intercooler 5, so that intake air is pressurized by exhaust pressure discharged from the engine 1 and is taken into an intake passage. . The intake air pressurized by the turbocharger 4 is cooled by the intercooler 5, thereby increasing the charging efficiency of the intake air.

The engine 1 is provided with a fuel injection pump 10 shown in FIG. 2, and each cylinder is provided with a fuel injection nozzle (not shown).
Then, fuel is pressurized to a high pressure by the fuel injection pump 10 and injected into each cylinder from a fuel injection nozzle. Also, as shown in FIGS. 1 and 2,
The fuel injection pump 10 includes a controller (control means) 1
2 is connected, and a rack and a timer of the fuel injection pump 10 are controlled based on a control signal from the controller 12 so that a fuel injection amount and a fuel injection timing injected from a fuel injection nozzle are controlled. Has become.

Next, the main parts of the apparatus will be described.
FIG. 2 is a schematic block diagram focusing on the function of the main part. As shown in FIG.
Includes an intake pressure sensor (intake pressure detection means) 14 for detecting intake pressure, an intake temperature sensor (intake temperature detection means) 16 for detecting intake temperature, and an engine speed sensor (engine speed) for detecting engine speed. Detection means) 18,
An engine load sensor (engine load detecting means) 20 for detecting an engine load is connected. The engine load sensor 20 detects an engine load by detecting, for example, the amount of depression of an accelerator pedal.

The controller 12 includes an ignition delay time calculating means 22, a pressure propagation time calculating means 24, an ignition delay crank angle calculating means 26, and a fuel injection timing setting means 28.
And a correction means 30 are provided. Here, the ignition delay time calculating means 22 calculates the intake pressure P and the intake temperature T detected by the intake pressure sensor 14 and the intake temperature sensor 16.
The ignition delay time τ1 from the time when fuel is injected into the combustion chamber to the time when the fuel is ignited is calculated based on the following equation (1). The ignition delay time τ1 is calculated by the following equation (1).

[0016] ^{τ1 = A · P a · (} Po 2 /0.21P) b · exp (E / RT) ······ (1) A, a, b: constants Po _2: O ₂ partial pressure E : Activation energy R: gas constant Here, assuming that the O ₂ ratio in the intake air is substantially constant, Po ₂ / P = B (constant) (2) If (2) is substituted into equation (1) and the constants are set to X and Y again, the ignition delay time τ1 can be expressed as in the following equation (3).

[0017] ^{τ1 = X · P a · exp} (Y / T) ······ (3) Further, the pressure propagation time calculating means 24, the fuel injection pump 1
Calculates the pressure propagation time from 0 to the fuel injection valve (ie, the fuel injection delay time from when the fuel injection pump 10 starts pumping the fuel until the fuel is actually injected by the fuel injection valve) τ2. The pressure propagation time τ2 is calculated by the following equation (4).

Τ 2 = l / a (4) l: fuel injection path length (fuel injection pipe path length) a: fuel injection pipe sound velocity Here, the fuel injection pipe sound velocity a is This is the speed at which the pressure wave is transmitted in the fuel injection pipe. By dividing the fuel injection path length l by the sound velocity a in the fuel injection pipe, the fuel is pressurized by the fuel injection pump 10 and then injected by the fuel injection nozzle. That is, the fuel injection delay time τ2 until the fuel injection is performed is calculated. Since the pressure propagation time (fuel injection delay time) τ2 does not depend on the operating state of the engine 1, it is stored in advance in the pressure propagation time calculation means 24 in the controller 12.

Expression (4) is a formula for calculating the fuel injection delay time when the fuel injection pump 10 is a line-type fuel injection pump, but when the electronic control unit injector is used,
The response delay of the solenoid valve and the time delay from the response of the solenoid valve to the actual fuel injection are summed to give a fuel injection delay time τ
It may be 2. Also, the ignition delay crank angle calculating means 2
6 is the engine speed Ne detected by the engine speed sensor 18, the ignition delay time τ1 calculated by the ignition delay time calculating means 22, and the pressure propagation time τ2 calculated by the pressure propagation time calculating means 24. The ignition delay crank angle θ ′ is calculated based on the above.

The ignition delay crank angle θ 'is defined as the ignition delay time τ1 and the pressure propagation time (fuel injection delay time) τ2
Is the angle at which the crankshaft of the engine 1 actually rotates during this period.
The actual ignition is later than the original ignition timing. The ignition delay crank angle θ ′ is calculated by the following equation (5).

Θ ′ = (Ne · 360/60) × (τ 1 + τ 2) (5) Further, the fuel injection timing setting means 28 is based on detection information from the engine speed sensor 18 and the engine load sensor 20. Thus, the reference fuel injection timing θ is set. Here, the fuel injection timing θ set by the fuel injection timing setting means 28 is an optimum fuel injection timing when the ignition delay time τ1 and the pressure propagation time τ2 are not taken into account. Therefore, the actual combustion start time (ignition time)
This delays the fuel injection timing θ by the ignition delay crank angle θ ′.

The fuel injection timing setting means 28 stores a map as shown in FIG. 3, and the fuel injection timing setting means 28 determines a reference fuel injection timing θ based on such a map. To be set. That is, this map shows the optimum fuel injection timing θ according to the engine speed Ne and the engine load λ.
For example, it is set to any of θ _{1 to} θ ₆ . The optimum fuel injection timing θ is set to be smaller as the numerical value of the subscript is larger.

The correction means 30 determines that the sum of the fuel injection timing θ set by the fuel injection timing setting means 28 and the ignition delay crank angle θ 'calculated by the ignition delay crank angle calculation means 26 is a predetermined value S. Is larger than the sum θ + θ ′ of the fuel injection timing θ and the ignition delay crank angle θ ′.
The actual fuel injection timing is advanced up to a value obtained by subtracting the predetermined value S from the above. The predetermined value S is a reference value for determining whether or not to advance the fuel injection timing θ, and is a time at which the fuel can be securely ignited without misfiring.

For this reason, the correction means 30 includes a reference value setting map 30a for setting the predetermined value (or reference value) S and an advance control section 30b for setting a control signal for advancing the fuel injection timing. It has. The reference value setting map 30a is, as shown in FIG.
8, the reference value S is set based on the engine speed Ne detected by the engine 8 and the engine load λ detected by the engine load sensor 20, and is substantially the same as the fuel injection timing θ setting map shown in FIG. The trend is set. That is, in the reference value setting map 30a, the reference value S is determined according to the engine speed Ne and the engine load λ.
Is set to, for example, _{one of} S _{1 to} S ₆ . However, the reference value setting map 30
In the case of a, the reference value S is set to be smaller as the subscript number is larger.

On the other hand, the advance angle control unit 30b calculates the sum θ + θ ′ of the fuel injection timing θ set by the fuel injection timing setting means 28 and the ignition delay crank angle θ ′ calculated by the ignition delay crank angle calculation means 26. It is determined whether or not θ + θ ′ is larger than the reference value S. If θ + θ ′ is larger than the reference value S, θ + θ ′ and the reference value S are set to prevent misfire of the engine 1. The fuel injection timing is advanced by an amount corresponding to the difference.

Therefore, in this case, the actual fuel injection timing θ _R is calculated by the following equation (6). θ _R = θ − [(θ + θ ′) − S] = S−θ ′ (6) Then, the advance angle control unit 30b renews such θ _R The control signal is set to the fuel injection pump 10 by setting the fuel injection timing θ. Also,
The fuel injection pump 10 starts fuel injection based on this control signal when the crankshaft rotation angle is θ (= S−θ ′).

Thus, even when atmospheric conditions such as intake air temperature and intake air pressure change, it is possible to set the optimum fuel injection timing. Since the fuel injection timing control device as one embodiment of the present invention is configured as described above, its operation is controlled according to, for example, a flowchart shown in FIG. First, step S1
In step S2, the intake temperature T is read, and in step S2, the intake pressure P is read. Then, in step S3, an ignition delay time τ1 is calculated based on the intake air temperature T and intake air pressure P read in steps S1 and S2. The ignition delay time .tau.1 is calculated by the ignition delay time calculating means 22 according to the above equations (1) to (3).

Next, in step S4, the pressure propagation time calculating means 24 calculates the pressure propagation time (fuel injection delay time) τ2 according to the equation (4). When the engine speed Ne is read in step S5, the ignition delay crank angle θ 'is calculated in step S6. The ignition delay crank angle θ 'is calculated by the ignition delay crank angle calculating means 26 in the ignition delay time τ1 calculated in step S3, the ignition delay time τ1 set in step S4, and the engine speed Ne read in step S5. , And is calculated according to equation (5).

When the engine load λ is read in step S7, in step S8, the process proceeds to step S8.
The reference fuel injection timing θ is set by the fuel injection timing setting means 28 based on the engine speed Ne read in step 5 and the engine load λ read in step S7. In step S9, a reference value S for determining whether or not to advance the fuel injection timing θ is set by the reference value setting map 30a of the correcting means 30 based on the engine speed Ne and the engine load λ. .

Then, in step S10, step S
The sum of the fuel injection timing θ set in step S8 and the ignition delay crank angle θ ′ calculated in step S6 is calculated in step S9.
It is determined whether or not it is larger than the reference value S set in. Here, the fuel injection timing θ and the ignition delay crank angle θ ′
Is smaller than the reference value S, the fuel injection timing θ returns with the initially set value.

If the sum of the fuel injection timing θ and the ignition delay crank angle θ ′ is larger than the reference value S, the routine proceeds to step S.
In step 11, the actual fuel injection timing θ is set as S−θ ′. That is, in this case, the ignition delay time τ1
And the pressure propagation time (fuel injection delay time) τ2 so that the actual ignition timing is not delayed from the reference value S.
The fuel injection timing θ is set as S−θ ′. Therefore, in this case, the fuel combustion start timing is S.

According to the fuel injection timing control apparatus as described above, even when atmospheric conditions such as intake air temperature and intake air pressure change, it is possible to set the optimal fuel injection timing and to prevent misfire. Can be prevented. For example, even when the engine 1 is operated under the condition of high altitude where the atmospheric pressure is low and the temperature is low (or the temperature of the engine cooling water is low), the correction of the intake pressure and the correction of the intake temperature reflect the fuel Since the injection timing can be controlled, the fuel injection can be performed at the optimal timing under all conditions. Also, NOx due to over-advanced fuel injection timing
This also has the advantage that the increase in the size can be suppressed.

Furthermore, the present apparatus has the advantage that it does not need to provide any new parts or the like and only needs to change the control logic in the conventional engine, so that the cost and weight do not increase. doing. Furthermore, the present device has the advantage that it does not need to provide new parts and the like for the conventional diesel engine and only needs to change the control logic, so that there is no increase in cost and weight. .

The fuel injection timing control device of the present invention
The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the turbocharger 4 and the intercooler 5 do not always need to be provided, and can be appropriately changed without departing from the gist of the present invention.

[0035]

As described above in detail, according to the fuel injection timing control apparatus of the present invention, the fuel injection timing of the diesel engine can be simply and reliably corrected according to the pressure and the temperature. Thus, there is an advantage that the fuel injection timing can always be controlled to the optimal one.

According to the fuel injection timing control device of the present invention, the fuel injection timing of the diesel engine can be simply and reliably corrected according to the pressure and the temperature, so that the optimum fuel injection is always achieved. There is an advantage that the injection timing can be controlled. That is, even when atmospheric conditions such as the intake air temperature and the intake air pressure change, the optimal fuel injection timing can be set, and misfire can be prevented. Since the fuel injection timing can be controlled by reflecting the correction of the intake pressure and the correction of the intake temperature, the fuel injection can be performed at an optimal timing under all conditions. This also has the advantage of suppressing an increase in NOx due to excessive advance of the fuel injection timing. Furthermore, the present device has the advantage that it does not require any new components or the like and only needs to change the control logic, so that the cost and weight do not increase. .

According to the third aspect of the present invention, the fuel injection timing control device according to the present invention provides a fuel injection
There is an advantage that fine fuel injection timing control can be executed.

[Brief description of the drawings]

FIG. 1 is a schematic overall configuration diagram of an engine to which a fuel injection timing control device as one embodiment of the present invention is applied.

FIG. 2 is a schematic block diagram illustrating a main part function of the fuel injection timing control device as one embodiment of the present invention.

FIG. 3 is a map for setting a basic fuel injection timing in a fuel injection timing control device as one embodiment of the present invention.

FIG. 4 is a map for setting a reference value of a fuel injection timing in a fuel injection timing control device as one embodiment of the present invention.

FIG. 5 is a flowchart for explaining an operation in the fuel injection timing control device as one embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 1 engine 2 intake passage 3 exhaust passage 4 turbocharger 5 intercooler 10 fuel injection pump 12 controller (control means) 14 intake pressure sensor (intake pressure detection means) 16 intake temperature sensor (intake temperature detection means) 18 engine speed sensor (engine) 20 engine load sensor (engine load detecting means) 22 ignition delay time calculating means 24 pressure propagation time calculating means 26 ignition delay crank angle calculating means 28 fuel injection timing setting means 30 correction means 30a reference value setting map 30b advance Angle control unit

Claims (3)

[Claims] 1. An intake pressure detecting means for detecting an intake pressure of an engine, an intake temperature detecting means for detecting an intake temperature, an engine speed detecting means for detecting a rotational speed of the engine, and the intake pressure detecting means. A fuel injection timing control device, comprising: control means for advancing a fuel injection timing based on detection information from the intake air temperature detection means and the engine speed detection means. 2. An ignition device, wherein the control means calculates an ignition delay time from fuel injection to ignition based on the intake pressure and intake temperature detected by the intake pressure detection means and the intake temperature detection means. Delay time calculating means, pressure propagation time calculating means for calculating a pressure propagation time from a fuel injection pump to a fuel injection valve of the engine, engine speed detected by the engine speed detecting means, and ignition delay time calculation Ignition delay crank angle calculation means for calculating an ignition delay crank angle from the ignition delay time calculated by the means and the pressure propagation time calculated by the pressure propagation time calculation means; Setting the fuel injection timing based on the detected engine speed and the engine load detected by the engine load detecting means. If the sum of the unit and, fuel injection timing ignition delay crank angle calculated by the fuel injection timing and 該着 fire delay crank angle calculating means which is set by the setting means is larger than a predetermined value,
Correction means for advancing the actual fuel injection timing up to an amount obtained by subtracting the predetermined value from the sum of the fuel injection timing and the ignition delay crank angle,
The fuel injection timing control device according to claim 1. 3. The system according to claim 2, wherein the predetermined value is set based on an engine speed detected by the engine speed detecting means and an engine load detected by the engine load detecting means. 3. The fuel injection timing control device according to 2.