JP3220844B2 - Fuel injection timing control system for vehicle diesel engine - Google Patents

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 apparatus for a diesel engine for a vehicle, and more particularly to a fuel injection timing control apparatus having an electronically controlled timer for controlling a fuel injection timing at the time of re-injection after a fuel cut. About.

[0002]

2. Description of the Related Art Conventionally, a fuel injection timing control system for a vehicle diesel engine using an electronically controlled timer maps fuel injection timing control data based on an operating state (engine speed, engine load, etc.). The control unit controls the timer device by searching the map for the injection timing corresponding to the detected value of the engine speed and the engine load at that time, searching the map for fuel injection timing control data based on the detected value of the engine operating state, and controlling the timer device. are doing.

[0003]

When fuel cut control for stopping fuel injection at the time of deceleration of a vehicle or the like functions for the purpose of improving fuel efficiency and engine braking force,
During subsequent fuel re-injection, the temperature in the combustion chamber of the engine is often low. However, the mapped fuel injection timing control data is set assuming the combustion chamber temperature in a steady state. For this reason, when the temperature in the engine combustion chamber decreases during fuel re-injection after the fuel cut,
The fuel injection timing based on the control data is lagging behind the originally required fuel injection timing. For this reason, there is a problem that unburned gas is discharged due to a delay in ignition of fuel immediately after the start of fuel re-injection and white smoke is easily generated.

At high altitudes where the atmospheric pressure decreases, the cylinder internal pressure decreases, so that the tendency of the fuel injection timing to be delayed with respect to the required fuel injection timing becomes even more remarkable. As a result, unburned gas is discharged immediately after the start of fuel re-injection, and white smoke is easily generated. Incidentally, a technique for advancing the fuel injection timing in accordance with the intake air temperature and the engine temperature (Japanese Utility Model Application Laid-Open No. 3-3524)
No. 0) and a technique for advancing the fuel injection timing during high idle operation at high altitude (Japanese Utility Model Laid-Open No. 73350).
However, neither of them solves the problem of the present invention.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a fuel injection timing control device for a vehicle diesel engine that can suppress generation of white smoke at the initial stage of fuel re-injection after fuel cut.

[0006]

Therefore, according to the first aspect of the present invention, as shown in FIG.
In a fuel injection timing control device for a vehicle diesel engine comprising a fuel injection timing adjusting means B for adjusting a fuel injection timing of the fuel injection means A based on an operating state, an engine operating state detecting means C; A fuel cut determining means for determining whether or not a fuel cut condition is satisfied based on a detection result of the state detecting means; Re-injection determining means E for determining whether or not fuel re-injection conditions after fuel cut are satisfied based on the detection result; and advancing the fuel injection timing at the beginning of fuel re-injection based on the determination result of the re-injection determining means E And a control means F for controlling the fuel injection timing adjustment means B for correction.

In this configuration, when the fuel cut determining means C determines that the fuel cut condition is satisfied based on the detected engine operating state, the fuel injection is stopped. Thereafter, when the engine operating condition satisfies the re-injection condition, the re-injection determination means D determines that re-injection has started, and re-injects fuel from the fuel injection means A.
In the initial stage of the re-injection, the control means F controls the fuel injection timing adjusting means B so that the fuel injection timing is advanced from the normal fuel injection timing set in advance based on the operating state.

According to the second aspect of the present invention, as shown in FIG. 2, the control means F includes a time measuring means G for measuring a time from the start of fuel cut to the fuel re-injection, and the time measuring means. A correction amount setting means H for increasing and setting the advance correction amount as the measurement time of G is longer is provided, and the advance of the fuel injection timing is corrected based on the set correction amount. With this configuration, the correction amount can be set according to the length of the fuel cut time, and the fuel injection timing can be controlled more optimally.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the altitude detecting means for detecting the altitude, and whether a detection value of the altitude detecting means is higher than a predetermined altitude is set. Altitude determination means for determining whether or not the altitude determination means determines that the altitude is higher than a predetermined altitude.

In such a configuration, when the altitude determining means determines that the altitude is higher than the preset altitude, the fuel injection timing is advanced in fuel re-injection after the fuel cut. According to a fourth aspect of the present invention, in the third aspect of the invention, the engine cooling water temperature detecting means and the water temperature for determining whether or not the detected value of the engine cooling water temperature detecting means is lower than a predetermined water temperature set in advance. A determination means, wherein the altitude determination means determines that the altitude is higher than a predetermined altitude, and when the water temperature determination means determines that the altitude is lower than a predetermined water temperature, the control means executes a fuel injection timing advance correction. did.

With this configuration, when the altitude determination means determines that the current altitude is higher than the preset altitude, and
When the engine coolant temperature determination means determines that the current engine coolant temperature is lower than the preset engine coolant temperature, the fuel injection timing is advanced when fuel is re-injected after the fuel cut.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the attached drawings. FIG. 3 is a configuration diagram of a first embodiment of a fuel injection timing control device for a vehicle diesel engine according to the present invention. In FIG. 3, a fuel injection pump 1 in a diesel engine is provided with an electronic timer 2 as a fuel injection timing adjusting means for adjusting a fuel injection timing.

On the other hand, the control unit 3 incorporating the microcomputer, based on signals from various sensors,
An optimal injection timing according to the operating state is calculated and a control signal is output to the electronic timer 2. Thus, the fuel injection timing from the fuel injection pump 1 is adjusted by the electronic timer 2, and fuel is injected and supplied into the combustion chamber of the engine (not shown) via the fuel injection nozzle 4. Here, the fuel injection pump 1 and the fuel injection nozzle 4 constitute a fuel injection unit.

As sensors for inputting signals to the control unit 3, there are provided a rotation sensor 5 for detecting an engine speed and an accelerator opening sensor 6 for detecting an accelerator opening. The control unit 3 has an optimum fuel injection timing map which is determined in advance based on the engine speed and the engine load (accelerator opening) assuming a normal state.
Normally, the fuel injection timing adjustment is executed using this map. Further, based on both the detection signals from the rotation sensor 5 and the accelerator opening sensor 6, a fuel cut determination and a fuel re-injection determination after the fuel cut are performed. It has a function of calculating the advance correction amount of the injection timing and performing the advance correction of the fuel injection timing. Therefore, the control unit 3 includes a fuel cut determination unit,
The functions of the re-injection determination means and the control means are provided as software. Further, the rotation sensor 5 and the accelerator opening sensor 6 correspond to operating state detecting means.

Next, the fuel injection timing control operation of this embodiment will be described with reference to the flowcharts of FIGS. FIG. 4 shows a main routine. In step 1 (hereinafter referred to as S1 in the figure, the same applies hereinafter), detection signals from the rotation sensor 5 and the accelerator opening sensor 6 are read. In step 2, based on the engine rotation speed N signal and the accelerator opening θ signal signal read in step 1, a pre-stored normal fuel injection timing map is used to determine the optimum fuel injection timing according to the operating state at that time. Search and set a certain normal advance amount.

In step 3, a fuel cut routine shown in the flowchart of FIG. 5 is executed. In step 4,
According to the result of the fuel cut routine, when there is no fuel cut, a control signal is output to the electronic timer 2 with the fuel injection timing as the normal advance amount set in step 2. Also,
At the time of fuel cut, a control signal is output to the electronic timer 2 as an advance amount corrected by a correction amount calculated as described later in the fuel injection timing at the initial stage of re-injection after the fuel cut.

Next, the operation of the fuel cut routine will be described with reference to the flowchart of FIG. In step 11, it is determined whether a fuel cut condition is satisfied. Here, for example, higher than the value n ₁ of the engine rotational speed N is set in advance (N>
n ₁ ) and the accelerator is OFF (accelerator opening θ =
At the time of 0), it is determined that the fuel cut condition is satisfied. When the fuel cut condition is not satisfied and the determination in step 11 is NO,
The flow ends as it is. On the other hand, if the determination in step 11 is YES as the fuel cut condition is satisfied, the process proceeds to step 12
Proceed to.

In step 12, time measurement is started by a timer for measuring the fuel cut time. In step 13,
A fuel re-injection determination is made. Here, the engine rotation speed N and the accelerator opening θ are monitored, and when the engine rotation speed N becomes lower than a preset value n ₂ (n ₁ > n ₂ ) (N <n ₂ ), or when the accelerator is ON (accelerator opening θ> 0)
Sometimes it is determined that fuel is re-injected. YES in step 13
If it becomes, go to step 6.

In step 14, the time measurement is completed, and the non-injection time during fuel cut is measured. Where step 12
Step 14 is the function of the time measuring means. Steps
In 15, the advance correction amount corresponding to the measured no-injection time is searched from the map showing the relationship between the no-injection time and the advance correction amount in FIG. 6 determined in advance. This step is the function of the correction amount setting means.

In step 16, the advance correction amount retrieved in step 15 is added to the normal advance amount set in step 2 of the main routine to calculate the advance amount of the fuel injection timing at the time of re-injection. The calculated advance amount is set as the fuel injection timing at the time of re-injection after the fuel cut, and the routine proceeds to step 4 of the main routine.
In, a control signal is output to the electronic timer 2 to correct the fuel injection timing.

In step 17, a pulse signal from the rotation sensor 5 is measured. In step 18, it is determined whether or not a value Nc of a counter that is counted up for each injection based on the number of pulse signals in step 17 has exceeded a preset value Np. At the time of re-injection after the fuel cut, fuel injection is performed at the fuel injection timing calculated in step 16. Nc> Np, and the judgment is Y
At the time of ES, fuel injection is performed with a normal advance amount calculated in the main routine.

FIG. 7 shows the relationship between the temperature in the cylinder and the injection timing (injection timing). As shown in the figure, when the fuel injection timing data matched assuming the normal cylinder temperature T in the normal state is used as in the related art, the case where the cylinder temperature decreases during the re-injection after the fuel cut is performed. Then, the injection timing (injection timing) is shifted to the retard side with respect to the required injection timing, and becomes a white smoke generation region (shown by oblique lines in the figure). In contrast, in the present embodiment, the temperature in the cylinder is estimated from the time from fuel cut to re-injection (no injection time), and the fuel injection timing is advanced as the non-injection time is longer (the temperature in the cylinder is lower). Since the correction is made to the corner side to match the required injection timing, it is possible to optimize the fuel injection timing at the initial stage of the re-injection after the fuel cut, thereby suppressing the discharge of unburned gas.

Next, a second embodiment of the present invention will be described. FIG. 8 shows the configuration of the second embodiment. The same parts as those in the configuration of the first embodiment shown in FIG. In FIG. 8, in the present embodiment, the first
In addition to the configuration of the embodiment, an altitude sensor 7 as altitude detecting means is provided, and a detection signal of the altitude sensor 7 is input to the control unit 3. When the altitude is higher than a predetermined altitude Hm, re-injection after fuel cut is performed. This is a configuration in which the advance angle is sometimes corrected.

FIG. 9 shows a flowchart of a fuel cut determination routine which is a main part of the second embodiment, and will be described. still,
The main routine is the same as that of the first embodiment shown in FIG. In FIG. 9, in step 21, the current altitude A is determined based on the altitude signal of the altitude sensor 7 input in step 1 of the main routine.
It is determined whether or not LT is higher than a predetermined altitude Hm. Here, the predetermined altitude Hm is set to an altitude before it becomes a white smoke area (shown by oblique lines in the figure) at a normal matching point as shown in FIG. 10, for example. And
If ALT> Hm is not satisfied (NO), the flow is terminated as it is, and the process returns to the main routine. If ALT> Hm (YES), proceed to step 22. This step 21 is the function of the altitude determination means.

In step 22, it is determined whether or not the fuel is cut as in the first embodiment. When the fuel is cut, the process proceeds to step 23. In step 23, it is determined whether or not re-injection is performed as in the first embodiment.
Proceed to 24. In step 24, the advance angle correction amount corresponding to the detected altitude is searched from the relationship between the altitude and the correction amount stored in advance.

In step 25, the fuel injection timing at the time of re-injection is calculated by adding the searched correction amount to the normal advance amount set in the main routine. Step 26, step 27
In the same manner as in the first embodiment, whether the fuel injection of the predetermined number Np has been executed with the corrected advance amount is monitored, and when the injection of the predetermined number Np ends, the process returns to the main routine.

FIG. 10 shows the relationship between the injection timing and the altitude. The higher the altitude is, the more the required injection timing shifts to the advance side. According to the second embodiment, even when the altitude increases and the internal pressure of the cylinder decreases to cause a situation in which white smoke is likely to be generated, the fuel injection timing is advanced and the generation of white smoke can be suppressed.

Next, a third embodiment of the present invention will be described. FIG. 11 shows the configuration of the third embodiment. The same parts as those in the configuration of the second embodiment shown in FIG. In FIG. 11, in the present embodiment, the second
In addition to the configuration of the embodiment, a water temperature sensor 8 as an engine cooling water temperature detecting means is provided, and a detection signal of the water temperature sensor 8 is input to the control unit 3 so that the detection altitude of the altitude sensor 7 is higher than a predetermined altitude Hm. and, when the detected water temperature Tw of the water temperature sensor 8 is lower than a predetermined water temperature Tw _0, a configuration in which advance angle correction for the time re-injection after the fuel cut.

FIG. 12 is a flowchart illustrating a fuel cut determination routine, which is a main part of the third embodiment, and will be described. still,
The main routine is the same as that of the first embodiment shown in FIG. In FIG. 12, in step 31, based on the altitude signal of the altitude sensor 7 input in step 1 of the main routine, the current altitude A
It is determined whether or not LT is higher than a predetermined altitude Hm. If the current altitude is not higher than the predetermined altitude Hm shown in FIG. 10 (NO), the flow is terminated and the process returns to the main routine. If ALT> Hm (YES),
Proceed to step 32.

[0030] In step 32, based on the water temperature signal of the water temperature sensor 8 is inputted in step 1 of the main routine, it is determined whether the current coolant temperature Tw is lower than a predetermined water temperature Tw ₀ set in advance. Here, the predetermined water temperature Tw ₀ is
For example, as shown in FIG. 13, the water temperature is set to a temperature before the white smoke area (shown by hatching in the figure) at a normal matching point. Then, Tw <Tw ₀ if not (N
O), end the flow and return to the main routine. If Tw <Tw ₀ (YES), the flow proceeds to step 33. This step 32 is the function of the water temperature determining means.

In step 33, it is determined whether or not a fuel cut is to be performed as in the second embodiment. When the fuel is cut, the process proceeds to step 34. In step 34, it is determined whether or not reinjection is performed as in the first embodiment.
Continue to 35. In step 35, an advance correction amount determined in consideration of the altitude and the water temperature stored in advance is searched.

In step 36, the fuel injection timing at the time of re-injection is calculated by adding the searched correction amount to the normal advance amount set in the main routine. Step 37, Step 38
Monitors whether or not the predetermined number Np of fuel injections has been executed with the corrected advance amount, as in the second embodiment, and returns to the main routine when the predetermined number of Np injections have been completed.

FIG. 13 shows the relationship between the injection timing and the water temperature. As the water temperature decreases, the required injection timing shifts to the advanced side. According to the third embodiment, when the altitude rises and the engine coolant temperature is low, and the fuel cut is performed, the fuel injection timing is advanced in the re-injection. When white smoke is reduced, generation of white smoke can be suppressed.

[0034]

As described above, according to the first aspect of the present invention, the advance of the fuel injection timing is corrected at the time of re-injection after the fuel cut, so that the discharge of unburned gas immediately after the re-injection of fuel can be reduced. Thus, the generation of white smoke can be reduced, and the exhaust characteristics and operability can be improved. According to the second aspect of the present invention, in addition to the effect of the first aspect of the present invention, it is not necessary to provide a sensor for detecting the temperature in the cylinder, and the manufacturing cost can be reduced.

According to the third and fourth aspects of the present invention, it is possible to suppress the discharge of unburned gas immediately after re-injection of fuel at high altitude where discharge of unburned gas immediately after re-injection of fuel is more remarkable. The generation of white smoke can be reduced, and the exhaust characteristics and operability at high altitude can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating the configuration of the invention according to claim 1;

FIG. 2 is a block diagram illustrating the configuration of the invention according to claim 2;

FIG. 3 is a configuration diagram of a first embodiment of the present invention.

FIG. 4 is a flowchart of a main routine of fuel injection timing control according to the first embodiment;

FIG. 5 is a flowchart of a fuel cut determination routine according to the first embodiment;

FIG. 6 is a diagram showing a relationship between an advance correction amount and a non-injection time;

FIG. 7 is a diagram showing a relationship between injection timing and cylinder temperature.

FIG. 8 is a configuration diagram of a second embodiment of the present invention.

FIG. 9 is a flowchart of a fuel cut determination routine according to the second embodiment;

FIG. 10 is a diagram showing a relationship between injection timing and altitude.

FIG. 11 is a configuration diagram of a third embodiment of the present invention.

FIG. 12 is a flowchart of a fuel cut determination routine according to the third embodiment.

FIG. 13 is a diagram showing a relationship between injection timing and engine water temperature.

[Explanation of symbols]

 Reference Signs List 1 fuel injection pump 2 electronic timer 3 control unit 4 fuel injection nozzle 5 rotation sensor 6 accelerator opening sensor 7 altitude sensor 8 water temperature sensor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-299894 (JP, A) JP-A-63-189633 (JP, A) JP-A-60-192855 (JP, A) JP-A 63-189855 88228 (JP, A) JP-A-63-9645 (JP, A) JP-A-2-227530 (JP, A) JP-A-61-43230 (JP, A) JP-A-59-94136 (JP, U) 6-350 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) F02D 41/12 385 F02D 41/04 385 F02D 41/40

Claims (4)

(57) [Claims] 1. A fuel injection timing control apparatus for a vehicle diesel engine, comprising: a fuel injection means; and a fuel injection timing adjusting means for adjusting a fuel injection timing of the fuel injection means based on an operation state. Detecting means, fuel cut determining means for determining whether a fuel cut condition is satisfied based on the detection result of the engine operating state detecting means, and the engine operating state after the fuel cut determination is made by the fuel cut determining means. Re-injection determining means for determining whether or not fuel re-injection conditions after fuel cut are satisfied based on the detection result of the detecting means; and advancing the fuel injection timing at the beginning of fuel re-injection based on the determination result of the re-injection determining means. A fuel injection timing control device for a vehicle diesel engine, comprising: control means for controlling a fuel injection timing adjustment means to correct an angle. The control means includes a time measurement means for measuring a time from the start of fuel cut to a fuel re-injection, and a correction amount setting means for increasing and setting an advance correction amount as the measurement time of the time measurement means is longer. 2. The fuel injection timing control apparatus for a vehicle diesel engine according to claim 1, wherein the fuel injection timing is advanced based on a set correction amount. 3. An altitude detecting means for detecting altitude, and altitude judging means for judging whether a detected value of the altitude detecting means is higher than a predetermined altitude set in advance, wherein the altitude judging means has a higher altitude than the altitude. 3. The fuel injection timing control device for a vehicle diesel engine according to claim 1, wherein the fuel injection timing advance correction by the control means is executed when it is determined that the fuel injection timing is high. 4. An engine cooling water temperature detecting means, and a water temperature judging means for judging whether or not a detected value of the engine cooling water temperature detecting means is lower than a predetermined water temperature set in advance, wherein the altitude judging means has a predetermined altitude. 4. The fuel injection timing advance correction by the control means when the water temperature is determined to be high and the water temperature determination means determines that the temperature is lower than a predetermined water temperature.
A fuel injection timing control device for a vehicle diesel engine as described in the above.