JP3077298B2 - Accumulation type fuel injection device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an accumulator type fuel injection device for an internal combustion engine.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 3-18645 discloses a pressure-accumulating fuel injection device for a diesel engine. In the accumulator type fuel injection device, the electronic control unit ECU
Calculates a command injection amount, a fuel injection timing, and a command common rail pressure based on detection data such as an engine speed, an accelerator opening, and an actual common rail pressure. Then, the amount of high-pressure fuel discharged from the high-pressure supply pump into the common rail is controlled by the deviation between the actual common-rail pressure and the command common-rail pressure. Further, while calculating the valve opening time of the injection valve according to the command injection amount and the actual common rail pressure, an injection valve command pulse is output at the fuel injection timing to inject high-pressure fuel accumulated in the common rail into each cylinder. I do. The common rail pressure pulsates due to the high-pressure fuel supplied by the high-pressure supply pump, the pressure drop at the time of injection, and the water hammer effect by closing the valve at the end of fuel injection (FIG. 7).

[0003]

However, the valve opening timing of the injection nozzle is advanced or retarded with respect to the top dead center due to the inherent characteristics of the engine even during steady operation, and the pulsation pattern of the common rail pressure is reduced. It doesn't work. For this reason, the sampling cycle of the actual common rail pressure is performed by time synchronization at regular time intervals, or the N
When performed in synchronization with a predetermined Ne pulse of the e pulses,
In any case, the actual common rail pressure detected varies,
There is a problem that the command injection amount of fuel and the actual injection amount do not match. The present invention has been made in order to solve the above-mentioned problems, and it is possible to reduce the deviation between the command injection amount and the actual injection amount to increase the accuracy of the fuel pumping control and the fuel injection amount control, thereby improving drivability. It is an object of the present invention to provide a pressure accumulating fuel injection device for an internal combustion engine that can be used.

[0004]

As specific means for achieving the above object, various kinds of detecting means 100 such as an engine speed, an accelerator opening and the like, a common rail pressure detecting means 101 as shown in FIG. An arithmetic processing means 102 for calculating a command injection amount, a fuel injection timing and a command common rail pressure according to a predetermined program based on detection signals of the various detecting means 100 and the common rail pressure detecting means 101;
A discharge amount control unit 103 for controlling a discharge amount of high-pressure fuel from a high-pressure supply pump into the common rail based on a deviation between the actual common rail pressure detected by the common rail pressure detection unit 101 and the command common rail pressure; In order to inject the high-pressure fuel stored in the cylinder into each cylinder, the injection valve opening time is calculated according to the command injection amount and the actual common rail pressure, and an injection valve command pulse is output at the fuel injection timing to perform the injection. In a pressure accumulating type fuel injection device for an internal combustion engine, comprising a fuel injection control means 104 for controlling valve opening, the common rail pressure detection means 10
The sampling of the actual common rail pressure 1 performs the injection
An accumulator-type fuel injection device for an internal combustion engine, which is performed during an injection period of a valve, is provided.

[0005]

According to the pressure accumulating fuel injection device for an internal combustion engine,
During the injection period of the injection valve , the common rail pressure detecting means 101
Performs sampling of the actual common rail pressure.

[0006]

An embodiment of the present invention will be described with reference to the drawings.
FIG. 2 shows a schematic configuration of a pressure accumulating fuel injection device for a diesel engine. In the diesel engine 1, an injector 2 is provided for a fuel chamber of each cylinder, and fuel injection from the injector 2 to the diesel engine 1 is controlled by turning on / off an injection control solenoid valve 3. The injector 2 is connected to a common high-pressure accumulator pipe, a so-called common rail 4, common to each cylinder. While the injection control solenoid valve 3 is open, the fuel in the common rail 4 is injected into the diesel engine 1 by the injector 2. Therefore, high-pressure fuel corresponding to the fuel injection pressure must be continuously stored in the common rail 4, and a high-pressure supply pump 7 is connected to a supply pipe 6 having a check valve 5 interposed therebetween.

The high-pressure supply pump 7 reciprocates a plunger with a cam (not shown) synchronized with the rotation of the diesel engine to bring the fuel sucked from the fuel tank 8 through the fuel supply pump 9 to a required high pressure. The discharge amount is increased and supplied to the common rail 4. The discharge amount control device 10 is provided to constantly maintain the common rail pressure at a predetermined high pressure.

The operation of the injection control solenoid valve 3 and the discharge amount control device 10 is controlled by a control signal output from an electronic control unit (hereinafter simply referred to as ECU) 11. E
The CU 11 receives detection signals from the engine speed sensor 12 and the accelerator opening sensor 13, and also receives inputs from a pressure sensor 14 for detecting an actual common rail pressure and various sensors 15 such as a water temperature, an intake air temperature, and an intake air pressure. A signal is input. The ECU 11 determines the operating state of the engine based on these input signals, performs arithmetic processing according to a predetermined program, and outputs an optimal control signal to the injection control solenoid valve 3 and the discharge amount control device 10. Also E
The CU 11 includes a memory (neither a RAM nor a ROM is shown) for storing detection data, a control program, and the like.

FIG. 3 is a flowchart showing the control of the apparatus of this embodiment by the ECU 11. First, step 2
At 01, the engine speed Ne is input by the detection signal of the engine speed sensor 12, and the accelerator opening Accp is input by the accelerator opening sensor 13. At step 202, command injection is performed using a characteristic map (not shown) according to a predetermined program. The quantity Q _FIN , the command common rail pressure P _FIN and the fuel injection timing T _FIN are calculated.

In step 203, the engine speed Ne
Is determined to be greater than the set minimum engine speed Ne _min , and if it is, the process proceeds to step 204 to determine whether or not the command injection amount Q _FIN is a positive value. Command injection amount Q
_{If FIN} is a positive value, at step 205, the common rail pressure P sampled by the pressure sensor 14 is obtained by the falling of the injection valve command pulse, that is, the pulse interrupt processing synchronized with the closing command of the injection control solenoid valve 3. capturing _CNT as the actual common rail pressure P _C.

In step 203, the engine speed Ne
If the pressure sensor is determined to be equal to or lower than the minimum engine speed Ne _min set to be low, the pressure sensor is interrupted at regular time intervals in step 206 to correct the pressure drop due to leaks and the like at the same time. 14 captures the common rail pressure P _CT was sampled as actual common rail pressure P _C. Further, in step 204, if the command injection quantity Q _FIN as isochronous deceleration is determined to 0 or less, as with the process proceeds to step 206, fetches the actual common rail pressure P _C by the time interrupt processing.

In Step 207, Step 205 is performed.
Injector commands are time interruption processing of the actual common rail pressure P _C or step 206 has been taken by the pulse interruption process based on the actual common rail pressure P _C captured by, and controls the opening and closing of the injection control solenoid valve 3 injector 2 A pulse energization start timing TT (hereinafter simply referred to as TT) and an energization time TQ (hereinafter simply referred to as TQ) are calculated.
TT is determined in terms of the fuel injection timing T _FIN time by Ne pulse and TQ is calculated from the relationship between the command injection quantity Q _FIN and the actual common rail pressure P _C by characteristic diagram shown in FIG. TT corresponds to the injection timing, and TQ corresponds to the injection amount.

FIG. 5A is a flow chart showing the pulse interruption process of the step 205. Step 30
In step 1, the common rail pressure detected by the pressure sensor 15 is converted from analog to digital. In Step 302 fetches the analog / digital conversion value as a common rail pressure P _CNT. FIG. 5B is a flowchart showing the time interruption processing in step 206. In step 401, the common rail pressure detected by the pressure sensor 14 is converted from analog to digital. In Step 402 fetches the analog / digital conversion value as a common rail pressure P _CT.

FIG. 6 shows an outline of the pulse interruption process. The timing for performing the pulse interruption is regulated based on the Ne pulse signal output from the pickup coil of the engine speed sensor 12. The engine speed sensor 12 is provided corresponding to a gear-shaped pulsar (not shown) synchronized with the rotation of the diesel engine 1, and outputs one pulse each time one tooth of the pulsar passes. Ne pulse No. At a timing of 0, a _TF counter for starting high-pressure fuel pumping from the high-pressure supply pump 7 to the common rail 4 is set at the high-pressure fuel pumping timing _TF . High pressure fuel pumping timing T _F, in order to control the actual common rail pressure P _C to the command common rail pressure P _FIN, both common rail pressure P _C and P
_{It is} obtained by ordinary PID control according to the deviation of _FIN .

Ne pulse No. At the timing of 5, the high-pressure fuel pumping timing _TF for the next cylinder is calculated. In addition, Ne pulse No. At the timing of 7, the injection valve command pulse is turned on at the timing of TT, turned off after TQ time, the injection control solenoid valve 3 is opened, and the fuel of the command injection amount Q _FIN is injected from the injector 2. , TT counter and TQ counter are set.

FIG. 7 is a timing chart of the apparatus of the present embodiment. In the case of time synchronization (FIG. 7 (E)) in which the common rail pressure is sampled every predetermined time, or Ne pulse synchronization (FIG. 7 (F)) in which the common rail pressure is sampled every predetermined number of pulses of the Ne pulse, The sampling value varies due to the pulsation of the common rail pressure. Since TQ and T _F are calculated based on this sampling value, a deviation occurs between the command injection amount Q _FIN and the actual injection amount, resulting in unstable control.

On the other hand, Ne pulse No. The actual common rail pressure P is sampled in synchronization with the falling timing of the injection valve command pulse, which is turned on at timing TT from timing 7 and turned off after TQ time.
_C is substantially equal to the actual injection pressure during the injection period. Therefore, even if retarded or output timing advance of the injection valve command pulse to the top dead center TDC, can be detected is substantially equal pressure on the actual injection pressure during the injection period as the actual common rail pressure P _C
(FIG. 7 (G)). Thus, by sampling the common rail pressure which is substantially equal to the actual injection pressure during the injection period and has no pulsation, stable control of the injection amount and the common rail pressure can be performed.

From the timing of Ne pulse No7, the high-pressure supply pump 7 operates at the high-pressure fuel pumping timing T _F for T _SS time solenoid valve.
(Not shown), and a predetermined amount of high-pressure fuel indicated by oblique lines in FIGS. FIG. 7
(H) and (I) show cam lifts of cams for reciprocating a plunger for pumping high-pressure fuel.

In the above-described embodiment, the common rail pressure is sampled in synchronization with the fuel injection of the injector, which is a main factor of the pulsation of the common rail pressure, and the feedback control is performed based on the sampled common rail pressure. , The effect of pulsation is eliminated and stable control can be performed. Therefore, when the common rail pressure causes pulsation or the like due to the fuel pumping of the high pressure supply pump, the common rail pressure is sampled in synchronization with the fuel pumping of the high pressure supply pump to eliminate the influence of pulsation or the like in the same manner as described above. Stable control can be performed.

[0020]

The present invention has the above-mentioned structure, and has a structure of an injection valve.
During the injection period, the common rail pressure detection means performs sampling of the actual common rail pressure. Since the common rail pressure which is substantially equal to the actual injection pressure during the injection period and has no pulsation can be sampled, the injection amount and the common rail pressure can be controlled stably. It is possible to reduce the deviation between the command injection amount and the actual injection amount, and improve the operability.

[Brief description of the drawings]

FIG. 1 is a diagram corresponding to claims.

FIG. 2 is a schematic configuration diagram of a pressure accumulating fuel injection device for a diesel engine.

FIG. 3 is a flowchart illustrating control of the apparatus according to the embodiment.

FIG. 4 is a characteristic diagram showing a relationship between an injection amount Q and an energization time TQ.

FIG. 5 is a flowchart showing an interrupt process.

FIG. 6 is an explanatory diagram showing an outline of a pulse interruption process.

FIG. 7 is a timing chart showing an operation.

[Explanation of symbols]

1 ... diesel engine, 2 ... injector,
3 ... solenoid valve for injection control, 4 ... common rail,
7 ... High pressure supply pump, 10 ... Discharge rate control device, 1
DESCRIPTION OF SYMBOLS 1 ... Electronic control unit (ECU), 12 ... Engine speed sensor, 13 ... Accelerator opening sensor, 14 ... Pressure sensor, 100 ... Detection means, 101 ... Detection of common rail pressure Means, 102 ... arithmetic processing means, 103 ...
Discharge amount control means; 104 ... fuel injection control means;

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) F02D 41/00-45/00 395 F02D 1/00-1/18

Claims (1)

(57) [Claims] 1. A command injection amount and a fuel injection according to a predetermined program based on various detection means such as an engine speed and an accelerator opening, a common rail pressure detection means, and detection signals of the various detection means and the common rail pressure detection means. Calculating means for calculating the timing and the command common rail pressure; and, based on a deviation between the actual common rail pressure detected by the common rail pressure detecting means and the command common rail pressure, a discharge amount of the high pressure fuel from the high pressure supply pump into the common rail. A discharge amount control means for controlling, and a valve opening time of an injection valve in accordance with the command injection amount and the actual common rail pressure for injecting high-pressure fuel accumulated in the common rail into each cylinder; A fuel injection control means for controlling the opening of the injector by outputting an injector command pulse to the internal combustion engine. A pressure accumulating fuel injection device for an internal combustion engine , wherein sampling of an actual common rail pressure performed by said common rail pressure detecting means is performed during an injection period of said injector .