JP3301095B2 - Injection pressure control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection pressure control device for an electronically controlled diesel system. In particular, the present invention refers to common rail pressure control of a high-pressure fuel injection device having a pressure accumulation pipe (common rail) used for a diesel engine or the like.

[0002]

2. Description of the Related Art Conventionally, as a technique in such a field, there has been a technique described in Japanese Patent Application Laid-Open No. 59-165858. Here, instead of a system including a mechanical fuel injection pump nozzle, in recent years, a so-called common rail type fuel injection system has been proposed as an electronically controlled injection device having better controllability. This system is an electronically controlled injection device for gasoline engines which is currently mass-produced as a known technology (referred to as "EFI, EGI, etc.").
Is applied to an injection device for a diesel engine, and the control thereof will be described below.

FIG. 11 is a diagram showing a relationship between a pump pre-stroke amount and a discharge amount, and FIG. 12 is a flowchart for explaining conventional feedback control. Using the relationship between the pump pre-stroke amount and the discharge amount as shown in FIG. 11, as shown in FIG. 12, the target injection pressure PFIN is calculated in step 300, the actual pressure Pc is fetched in step 301, and in step 302, ΔPc = P
FIN-Pc is calculated, and in step 303, ΔP
Calculates the proportional term TFBKP with respect to c, calculates the integral term TFBK with respect to ΔPc in step 304,
At 05, TFBK (i) = TFBK (i-1) + TFBKI + TFBKP
Is performed. Here, TFBK represents the pre-stroke amount of the discharge pump. In this manner, in the common rail pressure accumulation type injection system, the difference between the target injection pressure obtained from the engine speed and the load and the actual pressure in the common rail is feedback-controlled by controlling the discharge amount of the pressure accumulation pump.

[0004]

As described above, in the conventional fuel injection device, the difference between the target injection pressure obtained from the rotational speed and the load and the actual common rail pressure is controlled by controlling the discharge amount of the accumulator pump. Controlling. However, at the time of rapid deceleration such as after racing, even if the discharge of the pump is cut to reduce the discharge of the pump to zero because there is no relief mechanism for the accumulated fuel, the actual pressure does not decrease instantaneously and the deceleration idle The target pressure at that time is set to about the nozzle closing pressure for noise reduction, so there was a problem that even at a slight common rail pressure due to control overshoot, the nozzle closed and fuel was cut, leading to engine stall. .

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an injection pressure control apparatus which controls the actual pump pressure near a target value in a deceleration state and does not cause undershoot leading to engine stall.

[0006]

In order to solve the above problems, the present invention comprises a common rail for injecting fuel from an injector into a combustion chamber, and controlling the fuel supplied to the common rail by a pump control valve. In the injection pressure control device that feedback-controls the fuel pressure to the target value, the opening period of the injection control solenoid valve that controls the injection amount from the engine speed (N), the engine load (α), and the common rail pressure (Pc) ( TINT), the injection timing is controlled from the valve opening period (TINT), the engine speed (N) and the common rail pressure (Pc) corresponding to the injection amount determined by the injection amount control means. Opening timing of the solenoid valve for injection control (TT)
, An injector driving means for driving and controlling the injector by the two control means, and a pump control valve based on the valve opening period (TINT), engine speed (N) and common rail pressure (Pc). Determines the energizing pulse (TF) of (PCV) and learns the control command value of the pump control valve during idling.
Stored as a value, and the common rail pressure during deceleration.
And when the pressure deviation between the target value and the target value is equal to or less than a predetermined value.
Uses the energizing pulse (TF) using the stored learning value.
When the fuel pressure of the common rail is idling,
And a common rail pressure control means for controlling the pressure to a target pressure .

[0007]

According to the injection pressure control device of the present invention, the engine is provided with the injector for the combustion chamber of each cylinder,
Fuel injection from the injector to the engine is controlled by ON-OFF of an injection control electromagnetic valve by an injection amount control unit, an injection timing control unit, and an injector drive unit. The injector is connected to a high-pressure fuel pipe common to each cylinder, a so-called common rail. While the injection control solenoid valve is open, fuel in the common rail is injected from the injector to the engine. Further, high pressure fuel corresponding to the fuel injection pressure is continuously stored in the common rail,
The high-pressure fuel is supplied from the feed pump to the high-pressure pump and is pressurized. A pump control valve (PCV) that detects the pressure of the fuel pressurized by the high-pressure pump 5 with a pressure sensor of the common rail so that the pressure of the common rail becomes a predetermined value.
To release the high-pressure fuel to the high-pressure pump inlet side for control.
The injection control solenoid valve and the pump control valve (PCV), which are actuators according to the injection pressure control device, control the fuel injection amount and the fuel injection timing and the fuel pressure of the common rail. These control amounts are determined and commanded by an electronic control computer (ECU) in accordance with engine parameters (engine speed: N, engine load: α, engine water temperature, etc.). The present invention determines the fuel supply to the engine.
The control amount of the pump control valve (PCV) is controlled so that the common rail pressure fluctuates near a target value while monitoring the control state of the engine by the common rail pressure control means of the electronic control computer for instructing the pump control valve (PCV). The control command value is learned and stored at the time of idling, and at the time of engine deceleration, the stored learning value is reflected in the pump control command value so that the common rail pressure at the time of deceleration does not become a pressure equal to or less than the nozzle closing pressure. Prevent stalling due to undershoot.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an overall configuration of an injection pressure control device according to an embodiment of the present invention. The injection pressure control device shown in FIG. 1 is provided for an injector 1 which is disposed in a combustion chamber of each cylinder of an engine and injects fuel, and an injection control for ON-OFF controlling fuel injection from the injector 1 to the combustion chamber. A solenoid valve 2 and a high-pressure fuel pipe in which the injector 1 is connected in common to each cylinder;
A common rail 3 for injecting fuel from the injector 1 into the combustion chamber while the fuel pump is open, a feed pump 4 for supplying fuel, and a feed pump 4
And a high-pressure pump 5 for supplying fuel to the common rail 3 and continuously increasing the pressure to a high pressure corresponding to the fuel injection pressure. A pressure sensor 6 installed on the common rail 3 for detecting the pressure of the fuel, and a pressure of the common rail 3 detected by the pressure sensor 6 which escapes to the inlet side of the high-pressure pump 5 and is set to a predetermined value. A pump control valve (PCV) 7 for controlling the fuel pressure of the common rail 3 from the fuel injection amount and the fuel injection timing of the injection control electromagnetic valve 2 which is an actuator according to the present invention; : N, engine load: α, engine water temperature, etc.) and an electronic control computer (ECU) 8 for determining and issuing an instruction. Gin is pulser opposed to arranged the crankshaft including an engine speed sensor 9 for detecting an engine emission speed signal and the cylinder identification signal, respectively, and a cylinder discrimination sensor 10.

[0009] The present invention determines the fuel supply to the engine.
The control amount of the pump control valve (PCV) 7 is controlled so that the common rail pressure fluctuates near a target value while monitoring the control state of the engine by the electronic control computer (ECU) 8 which instructs the common rail pressure. This is to prevent stalling due to shooting.

FIG. 2 is a diagram showing a control block of an electronic control computer (ECU) according to an embodiment of the present invention.
An electronic control computer (ECU) 8 shown in FIG. 3 controls the injection control solenoid valve 2 that controls the injection amount based on the engine speed (N), the engine load (α), and the common rail pressure (Pc) for an opening period ( the injection quantity control means 11 calculates and determines the TINT), the valve opening period (TINT) and the engine speed corresponding to the injection quantity determined by the injection quantity control means 11 described above (N) and co mode Nreru pressure (Pc Injection timing control means for calculating and determining the valve opening timing (TT) of the injection control solenoid valve 2 using the cylinder discrimination signal (G) for determining the injection cylinder in order to control the injection timing from the above. An injector driving means 13 for controlling the operation of the injector 1 by the two control means 11 and 12; a valve opening period (TINT) corresponding to the injection amount, as well as the injection timing; From the number (N) and the common rail pressure (Pc), a cylinder discrimination signal (G) for driving the pump control valve (PCV) 7 corresponding to the injection cylinder.
, The common rail pressure control means 1 for calculating and determining the energizing pulse (TF) of the pump control valve (PCV) 7
4 is included.

FIG. 3 is a block diagram illustrating the common rail pressure control means in FIG. As shown in this figure,
As described above, the common rail pressure control means 14 calculates a common rail target value (PF) corresponding to the engine condition from the driving pulse (TINT) of the injection control solenoid valve 2 corresponding to the engine speed (N) and the fuel injection amount. A common rail pressure target value calculating means 21 for calculating, and a pump control for comparing the actual pressure value (Pc) from the pressure sensor 6 with the target value (PF) and controlling the common rail pressure so that the pressure value becomes the target value. A PCV control command value calculating means 22 for calculating and outputting a command value (TFBK) of the valve (PCV) 7; and as an essential part of the present invention, an engine accelerator opening (α); A stable state discriminating means 23 for judging from the engine speed (N), etc .; and a pump which operates only when the stable state discriminating means 23 is in a stable state. Feedback command value (Δ
T) learning / integrating / updating, learning value updating means 24 for storing in a non-volatile memory, deceleration-time determining means 25 for determining a deceleration state based on the engine accelerator opening (α), etc., and learning value updating means 24. After the common rail pressure feedback is stopped when the pressure deviation (ΔP) is equal to or less than the predetermined value, the stored learning value is taken out, and the basic control command value of the pump control valve (PCV) 7 is reflected as an integrated value ΣΔT. A learning value extracting / correcting means 26 for controlling the command value (TFBK) of the pump control valve (PCV) 7 so as to prevent the pressure from falling below the valve closing pressure and preventing engine stall due to undershoot of the common rail pressure.
And

FIG. 4 is an operation timing chart according to this embodiment. As shown in this figure, when the engine state is switched from the steady operation to the deceleration operation mode, the target value (PF) of the common rail pressure changes to the low pressure side and the actual pressure (P
The following control is performed so that c) becomes the target value (PF).
First, in the conventional control (broken line) before the improvement, the pump final command value (TFBK) is determined by the sum of the base command value (TBASE) and the feedback correction value (TFB), and the common rail actual pressure (Pc) is set to the target value (TFc). Since the feedback control similar to that immediately after the start of deceleration was performed even after the vicinity of PF), the control was over-controlled due to a delay in the control system including a delay in the hydraulic system of the pump, and the pump discharge amount was reduced more than necessary, and the common rail was reduced. The actual pressure (Pc) undershooted, leading to engine stall. On the other hand, the control after improvement of the present invention (solid line) is the common rail actual pressure (P
When c) becomes close to the target value (PF), the learning value (ΣΔT) learned and stored in the idling stable state is used as the feedback correction amount, and the feedback is stopped for a predetermined time to prevent overcontrol due to the delay of the control system, and the pump An undershoot of the common rail actual pressure (Pc) due to an unnecessarily reduced discharge amount can be avoided, and engine stall can be prevented.

FIGS. 5 and 6 are control flowcharts according to the present embodiment for realizing the timing chart of FIG. 4 (parts 1 and 2). As shown in FIG.
Then, various parameters for engine control are fetched from various sensors for detecting the engine operating state. Step 1
At 01, the injection system control amount is determined from the information taken in step 100. That is, the fuel injection amount (q) is determined from the accelerator opening (α) and the engine speed (Ne), and the fuel injection timing (θ) is determined from the fuel injection amount (q) and the engine speed (Ne).

In step 102, the engine speed (N
e) and an injection pressure target value (PF) is calculated from the injection amount command value (q). In step 103, a pump basic command value (TBASE) for controlling the pump control valve (PCV) 7 corresponding to the target pressure is calculated from an engine speed (Ne) and an injection amount command value (q).

In step 104, the common rail pressure sensor 6 captures the actual rail pressure (Pc). Step 1
05, the actual rail pressure (Pc) and the target rail pressure (P
F) and the pressure deviation (ΔP) is calculated. Step 106
Then, the correction amount (TFB) of the pump command value according to the pressure deviation (ΔP) is calculated.

The following steps 107 to 119 relate to the control method according to the present invention and will be described in order. In step 107, it is determined whether or not the engine is in a deceleration state based on the accelerator sensor opening and the accelerator fully closed signal (LLON). In step 109, if it is determined in step 107 that the vehicle is not in the deceleration state, the process proceeds to this step, in which the pump basic command value (TBAS
E) and the pump command value correction amount (TFB) are added to calculate the pump final output (TFFB).

In step 108, step 107
If it is determined that the vehicle is in a deceleration state, the process proceeds to this step, and it is determined whether or not the pressure deviation (ΔP) calculated in step 105 is equal to or smaller than a predetermined value (Ps). The process proceeds to step 110, and if the value is equal to or smaller than the predetermined value, the process proceeds to step 110. In step 110, in order to detect the control amount in the stable state, it is determined whether or not the duration of the idle state is equal to or longer than a predetermined value.

In step 111, step 110
When the vehicle is in the deceleration state, the process proceeds to this step, and the idle correction learning value (ΣΔT) in the nonvolatile memory is extracted without performing feedback. In step 112, the pump basic command value (TBASE) calculated in step 103 is added to the idle correction learning value (ΣΔT), and the pump final output (TFBK) is added.
).

In step 113, if the idle state continuation time exceeds a predetermined value in step 110, it is determined whether or not there is learning during idling. In step 114, if the learning is performed in step 113, the previous learning value (ΣΔT _i-1 ) is set as the learning value (ΣΔT). In step 115, if there is no learning in step 113, the learning initial value (ΔTIN) is set as the learning value (ΣΔT).

In step 116, it is determined whether or not the pressure deviation (| ΔP |) resulting from the previous learning correction control result is within a predetermined value (a), and it is determined whether further learning is required. In step 117, if learning is required, a pump correction value (TFB) corresponding to the pressure deviation (ΔP) is calculated.

In step 118, the current learning value (ΣΔT _i ) is reflected on the previous pump idling learning value (ΣΔT). In step 119, if the learning is sufficient, the learning value (ΣΔT) is stored in the nonvolatile memory. After the end of the steps 118 and 119, the process proceeds to the above-described step 112, where processing for reflecting the learning correction value is performed, and step 1 is performed.
At step 20, the output of each command value (q, θ, TFBK) is set, and the control ends.

The contents of the present invention are executed while repeating the control of steps 100 to 120. FIG. 7 is a diagram showing a comparison between the initial value of the idle learning value and the value after learning. As shown in the figure, the initial value of the learning according to step 115 of this embodiment is a value on the maximum side of the pump discharge amount that can prevent undershoot in anticipation of deterioration over time and initial variation due to the common rail pressure even in the initial state. It is set so as to suppress the discharge amount accordingly.

FIG. 8 is a diagram showing a correction characteristic when a predetermined value (Ps) for determining the pressure deviation (ΔP) is operated in accordance with the amount of the learning value. The same effect can be obtained by operating as shown in FIG. Further, in this embodiment, the pump control command value is operated, but the same effect as in the above embodiment can be obtained by increasing / decreasing the common rail pressure target value according to the learning value and setting / operating the guard value in the pump control command value. Needless to say.

FIG. 9 is an operation timing chart according to another embodiment, and FIG. 10 is a control flowchart for realizing the timing chart of the embodiment of FIG. In the present embodiment, a guard is provided in the integral correction term for the discharge amount control (PI control), and the guard value is learned in an idle state, thereby preventing a decrease in the actual injection pressure. As shown in FIG. 10, in step 201, a target pressure PFI is calculated from the engine speed (N) and the load.

Next, in step 202, the actual pressure Pc is taken from the pressure sensor 6 attached to the common rail 3. In step 203, a difference ΔPc from the target is calculated. In steps 204 and 205, ΔPc
Calculate the proportional and integral correction amounts with respect to. Up to this point, it is the same as the conventional one.

Next, at step 206, the fall of the actual Pc is judged, and if the fall amount is within the set value (-1 MPa), the routine exits from the routine with the current integral amount at step 209. If the value is equal to or greater than the set value in step 207, the integrated value TFBKI is determined to be larger or smaller than the idle learning value TFBKL.

In step 208, if TFBKI is larger, a guard is provided by setting TFBKI '= TFBKL. In step 210, the final pre-stroke amount FFB
Calculate K and exit the feedback routine. According to the present embodiment, as shown in FIG. 9, it is possible to prevent pressure undershoot at the time of deceleration (at the time of transition), and to prevent the occurrence of troubles such as engine stall.

[0028]

As described above, according to the present invention, in the common rail type fuel injection system, the electronic control computer for determining and instructing the amount of fuel supplied to the engine determines the stable state of the engine and determines the pump control valve (PCV). )
Learning and storing the control command value, and when the pressure deviation between the common rail actual pressure and the target value at the time of engine deceleration becomes equal to or less than a predetermined value, common rail pressure feedback is stopped, and the stored learning value is reflected in the pump control command value. As a result, the common rail pressure during deceleration does not become a pressure equal to or less than the nozzle closing pressure, and it is possible to prevent engine stall due to undershoot of the common rail pressure. Further, by setting the common rail pressure at the time of idling to a low value near the nozzle closing pressure, an excellent effect that a comfortable system without engine stall can be realized even if the adaptation with emphasis on combustion noise is performed.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an overall configuration of an injection pressure control device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a control block of an electronic control computer (ECU) according to the embodiment of the present invention.

FIG. 3 is a block diagram illustrating a common rail pressure control unit in FIG.

FIG. 4 is an operation timing chart according to the embodiment.

FIG. 5 is a control flowchart according to the present embodiment for realizing the timing chart of FIG. 4 (part 1).

FIG. 6 is a control flowchart according to the present embodiment for realizing the timing chart of FIG. 4 (part 2).

FIG. 7 is a diagram showing a comparison between an initial value of an idle learning value and a value after learning.

FIG. 8 is a diagram illustrating a correction characteristic when a predetermined value (Ps) for determining a pressure deviation (ΔP) according to another embodiment is operated according to the amount of a learning value.

FIG. 9 is an operation timing chart according to another embodiment.

FIG. 10 is a control flowchart for realizing the timing chart of the embodiment in FIG. 9;

FIG. 11 is a diagram showing a relationship between a pump pre-stroke amount and a discharge amount.

FIG. 12 is a flowchart illustrating a conventional feedback control.

[Description of Signs] 1 ... Injector 2 ... Injection control solenoid valve 3 ... Common rail 4 ... Feed pump 5 ... High pressure pump 6 ... Pressure sensor 7 ... Pump control valve (PCV) 8 ... Electronic control computer (ECU) 9 ... Engine Revolution speed sensor 10 ... Cylinder discrimination sensor 11 ... Injection amount control means 12 ... Injection timing control means 13 ... Injector drive means 14 ... Common rail pressure control means 21 ... Common rail pressure target value calculation means 22 ... PCV control command value calculation means 23 ... Stable State determination means 24 ... Learning value update means 25 ... Deceleration time determination means 26 ... Learning value extraction correction means

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-645 (JP, A) JP-A-62-233437 (JP, A) JP-A-61-87933 (JP, A) JP-A 63-645 50649 (JP, A) JP-A-5-52146 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 41/38-45/00 395 F02M 55/02

Claims (3)

(57) [Claims] 1. An injection pressure control device comprising: a common rail for injecting fuel from an injector into a combustion chamber; and controlling fuel supplied to the common rail by a pump control valve to feedback-control the fuel pressure of the common rail to a target value. An injection amount control means for determining an opening period (TINT) of an injection control solenoid valve for controlling an injection amount from an engine speed (N), an engine load (α) and a common rail pressure (Pc); In order to control the injection timing from the valve opening period (TINT), the engine speed (N), and the common rail pressure (Pc) corresponding to the injection amount determined in the above, the valve opening timing (TT) of the injection control solenoid valve is determined. Injection timing control means for determining, injector driving means for driving and controlling the injector by the two control means, and the valve opening period (TIN T), the engine speed (N) and the common rail pressure (Pc) from the pump control valve (PC
And determines the V) energizing pulse (TF), idle
The control command value of the pump control valve at the time is stored as a learning value
The common rail pressure and the target value during deceleration.
When the pressure deviation from the
Lus (TF) is calculated using the stored learning value.
When the fuel pressure of the Monrail is
And a common rail pressure controlling means for controlling such that
Injection pressure control apparatus characterized by that. 2. The injection pressure control device according to claim 1, wherein
The energizing pulse (TF) of the engine pressure means
Pump basic calculated from number of turns (Ne) and injection quantity (q)
Command value (TBASE) and common rail pressure (PC)
Obtained according to the pressure deviation (ΔP) from the standard value (PF)
Calculated based on the sum with the correction amount (TFB),
Control the pump control valve based on the
The fuel pressure of the common rail
Feedback control, The stored learning value is the correction amount during idling.
Is a value obtained by learning and During deceleration, the common rail pressure and the target value
Pressure deviation is below specified value When the learning memory
From the sum of the calculated value and the basic command value, the energizing pulse
The injection pressure control according to claim 1, wherein the injection pressure is calculated.
Control device. 3. The injection pressure control device according to claim 1, wherein
The energizing pulse (TF) of the engine pressure means is
Pump basic calculated from number of turns (Ne) and injection quantity (q)
Command value (TBASE) and common rail pressure (PC)
Obtained according to the pressure deviation (ΔP) from the standard value (PF)
Calculated based on the sum of the proportional correction amount and the integral correction amount,
The pump control valve is controlled based on the energizing pulse (TF).
Control the fuel pressure of the common rail
Is to feedback control the force to the target value. The stored learning value is the integral compensation value at the time of idling.
It is a value that learned and memorized a positive amount, During deceleration, the common rail pressure and the target value
When the pressure deviation falls below a predetermined value, the learning memory
From the sum of the calculated value, the basic command value, and the proportional correction amount,
2. The method according to claim 1, wherein the energizing pulse is calculated.
Injection pressure control device.