JPH07103013A - Accumulation type fuel injection device - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a pressure-accumulation fuel injection device capable of increasing supercharging pressure without adding an auxiliary device. [Structure] The diesel engine 201 includes a plurality of injection valves 20.
Fuel is injected from 2. The fuel is pumped up from the tank 208 by the low pressure pump 209 and boosted by the high pressure pump 207, and the common rail 2 to which the injection valve is attached.
03. The diesel engine is controlled by the ECU 215. In the present invention, in addition to the main fuel injection performed in the compression stroke, after-fuel injection is performed in the expansion stroke to increase the exhaust gas pressure when in a specific operating state, Increases turbocharger turbine output to increase intake pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure-accumulation fuel injection device applied to a diesel engine with a supercharger, and more particularly to a pressure-accumulation fuel injection device capable of increasing supercharging pressure to improve acceleration performance. .

[0002]

2. Description of the Related Art As a fuel supply device for supplying fuel to an internal combustion engine, a pressure accumulating fuel injection for injecting pressurized fuel into each cylinder from a fuel injection valve connected to a common rail installed along the internal combustion engine. The device is publicly known (see, for example, JP-A-62-258160).

Such an accumulator fuel injection device is mainly applied to a diesel engine, and the amount of fuel injected into a cylinder is the amount of fuel supplied to a common rail that can be operated independently, the pressure, and the fuel injection valve. It is controlled by the opening period. Further, although the diesel engine is inferior in acceleration to the gasoline engine, in order to improve this drawback, it is general to employ so-called supercharged intake air in which the pressure of the intake air is increased by a turbocharger or a supercharger.

FIG. 19 is a schematic view of a supercharged intake system using a turbocharger, which is one cylinder 2 of an internal combustion engine 201.
A piston 251 that moves up and down in the cylinder is installed in the cylinder 50. Further, the fuel injection valve 20 is provided on the top of the cylinder 250.
2, an intake valve 253 and an exhaust valve 255 are installed.

An intake pipe 252 supplying intake air to the intake valve 253, and an exhaust pipe 25 exhausting exhaust gas to the exhaust valve.
4 is connected. A compressor 256 is installed in the intake pipe,
A turbine 258 is installed in the exhaust pipe 254,
The compressor 256 and the turbine 258 are directly connected by a shaft 257.

FIG. 20 is a cycle diagram of a diesel engine in which the horizontal axis represents the specific volume v of the gas in the cylinder and the vertical axis represents the pressure P of the gas in the cylinder. The stroke from the point f to the point g is the exhaust stroke, and the pressure difference ΔP is the driving force of the turbine 256. However, in single-stage supercharging, it is difficult to set the pressure ratio (ratio of intake pressure to atmospheric pressure) to "4" or more.

Therefore, in order to further improve the acceleration performance, two-stage supercharging is used, and an afterburner is installed between the internal combustion engine and the exhaust turbine (for example, JP-A-55-153).
No. 818) or a two-stage supercharger with an afterburner (for example, Japanese Patent Laid-Open No. 63-309727).

[0008]

However, in the method of improving acceleration according to the above-mentioned proposal, it is necessary to additionally provide auxiliary devices such as an afterburner, a catalyst or a movable vane nozzle, and the structure becomes complicated. Is inevitable. The present invention has been made in view of the above problems, and an internal combustion engine equipped with a pressure-accumulation fuel injection device has a feature that it is possible to open a fuel injection valve regardless of a stroke, and an auxiliary device is added. An object of the present invention is to provide a pressure accumulating fuel injection device capable of increasing supercharging pressure without installing the fuel injection device.

[0009]

FIG. 1 is a basic configuration diagram of a pressure-accumulation type fuel injection device according to a first aspect of the present invention, and a specific operation for detecting that a diesel engine with a supercharger is in a specific operation state. State detection means 11 and specific operation state detection means 1
Fuel injection mode determination means 12 for determining whether or not the vehicle is in an operating state in which after-fuel injection is to be executed in addition to main fuel injection when a specific operating state quantity is detected by 1.
The main fuel injection execution means 13 for executing the main fuel injection in the compression stroke when the fuel injection mode determination means 12 determines that the operation state in which the after fuel injection is not to be executed is performed, and the fuel injection mode determination means 12 After-fuel injection executing means 14 for executing after-fuel injection in the expansion stroke in addition to main fuel injection by the main-fuel injection executing means when it is determined that the operating state in which after-fuel injection should be executed is determined.

In the pressure-accumulation type fuel injection device according to the second aspect of the present invention, the after-fuel injection is stopped by the after-fuel injection executing means 14 when the after-fuel injection is executed after a predetermined time. After-fuel injection stopping means is provided.

[0011]

In the pressure-accumulation fuel injection device according to the first aspect of the invention, in addition to the main fuel injection executed in the compression stroke, when the operating condition detected by the operating condition detecting means is a specific operating condition, After-fuel injection is executed in the expansion stroke. Therefore, the energy of the exhaust gas to be exhausted increases, so that the driving force of the turbocharger or supercharger increases and the boost pressure is increased.

In the pressure-accumulation type fuel injection device according to the second aspect of the present invention, after-fuel injection is stopped when the after-fuel injection is performed after a predetermined time.

[0013]

FIG. 2 is a block diagram of an embodiment of a pressure-accumulation type fuel injection device according to the present invention, which is a 6-cylinder diesel engine 20.
Fuel injection valves 202a to 202f corresponding to each cylinder of No. 1
(Only four are shown), but the fuel injection valve 2
02a to 202f are connected to a common rail 203 installed along the diesel engine 201, and fuel is injected while the injection control solenoid valves 204a to 204f are excited.

The common rail 203 has a fuel supply pipe 20.
A high-pressure fuel pump 207 is connected via the valve 5 and the check valve 206. The high-pressure fuel pump 207 is supplied with the fuel stored in the fuel tank 208 by the low-pressure fuel pump 209. A discharge amount control device 210 is installed in the high-pressure fuel pump 207, and the common rail 20
Adjust the amount of fuel supplied to No. 3.

The common rail 203 includes the common rail 20.
A pressure sensor 211 for detecting the pressure inside 3 is installed. Further, a rotation speed sensor 212 that detects the rotation speed of the diesel engine 201, an accelerator opening sensor 213, and a vehicle speed sensor 214 are installed. The fuel injection timing for each cylinder is controlled by the ECU 215. ECU2
Reference numeral 15 is a microcomputer including a bus 215a, a CPU 215b, a memory 215c, an input interface 215d and an output interface 215e.

A pressure sensor 211, a rotation speed sensor 212, an accelerator opening sensor 213 and a vehicle speed sensor 214 are connected to the input interface 215d. The output interface 215e has a solenoid valve 204 for injection control.
a to 204f and the discharge amount control device 210 are connected. The intake manifold 2 of the diesel engine 201
A turbocharger (supercharger) 218 is mounted between the exhaust gas manifold 16 and the exhaust manifold 217 to collect the energy of the exhaust gas and pressurize the intake air.

FIG. 3 is a flow chart of a specific operation state detection routine executed by the ECU 215. The vehicle speed SP detected by the vehicle speed sensor 214 in step 301.
D, the engine speed Ne detected by the rotation speed sensor 212 and the accelerator opening ACC detected by the accelerator opening sensor 213 are read. In step 302, it is determined whether the vehicle speed SPD is equal to or higher than a predetermined threshold value α, and if a positive determination is made, the process proceeds to step 303.

In step 303, the engine speed Ne
Is greater than or equal to a predetermined threshold β, and if an affirmative decision is made, the operation proceeds to step 304. In step 304, it is determined whether or not the main fuel injection amount QMFIN calculated in the main fuel injection routine, which will be described later, is greater than or equal to a predetermined threshold value γ, and if a positive determination is made, the process proceeds to step 305.

In step 305, the accelerator opening A
It is determined whether CC is greater than or equal to a predetermined threshold value δ, and if an affirmative determination is made, the process proceeds to step 306. In step 306, the flag AINJ indicating execution of after fuel injection is set to "1", and this routine is ended. When a negative determination is made in any of steps 302 to 305, the routine proceeds to step 307, the flag AINJ is reset, and this routine is ended.

FIG. 4 is a flow chart of a first fuel injection valve control routine executed by the ECU 215, which is executed by the revolution pulse counter CNENO for each value of "0" to "7". The rotation speed pulse counter CNENO has a rotation speed sensor 21 for each 15 ° cam angle of the diesel engine.
The number of pulses output from 2 is counted,
The count from "0" to "7" is repeated.

In step 401, the rotation speed pulse counter C
It is determined whether NENO is not equal to the main fuel injection reference value CNEM. If an affirmative decision is made in step 401, the routine proceeds to step 402, where it is decided whether or not the flag AINJ is set to "1". If an affirmative decision is made, the routine proceeds to step 403, where the after-fuel injection timer setting processing is executed.

When the result in step 401 is negative, the main fuel injection surplus time timer TTMF is set in step 404, and the main fuel injection energization time timer TQM is set in step 405, and this routine ends. If a negative determination is made in step 402, this routine is directly ended. FIG. 5 is a detailed flowchart of the after-fuel injection timer setting process executed in step 403 of the fuel injection control routine of FIG.

In step 501, the cylinder counter CCYL
It is determined whether N is equal to "1", "3" or "5". If an affirmative decision is made in step 501, the operation proceeds to step 502, and the rotation speed pulse counter CNEN
It is determined whether O is the first after-fuel injection reference value CNEP1.

If an affirmative decision is made in step 502, the routine proceeds to step 503, where the value obtained by adding "8" to the rotation speed pulse counter CNENO is the second after-fuel injection reference value C.
It is determined whether it is NEP2. If an affirmative decision is made in step 503, this processing is immediately terminated. When a negative determination is made in step 501, the process proceeds to step 504,
It is determined whether the rotation speed pulse counter CNENO is the second after-fuel injection reference value CNEP2.

If an affirmative decision is made in step 504, the routine proceeds to step 505, where the value obtained by adding "8" to the rotation speed pulse counter CNENO is the first after-fuel injection reference value C.
It is determined whether it is NEP1. If an affirmative decision is made in step 505, this processing is immediately terminated. When a negative determination is made in step 502 or step 505, the process proceeds to step 506, the first after-fuel injection surplus time timer TTPF1 is set, and the process proceeds to step 508.

If a negative determination is made at step 503 or step 504, the routine proceeds to step 507, where the second after-fuel injection surplus time timer TTPF2 is set and the routine proceeds to step 508. In step 508, the after fuel injection energization time timer TQP is set and this routine is ended.

FIG. 6 is a flow chart of a second fuel injection valve control routine, which is a rotation speed pulse counter CNEN.
It is executed every time O is "6". In step 601, the main fuel injection setting process is performed, and the flow proceeds to step 602, where it is determined whether the cylinder counter CCYLN is not equal to "1", "3" or "5".

If an affirmative decision is made in step 602, the routine proceeds to step 603, where the first after-fuel injection setting processing is carried out, and this routine is ended. Step 602
If a negative decision is made at step 604, the routine proceeds to step 604, where the second
After-fuel-injection setting processing is performed, and this routine ends. FIG. 7 is a flowchart of the main fuel injection setting process executed in step 601 of the second fuel injection valve control routine shown in FIG. 6, and in step 701, it is a function of the main fuel injection amount QMFIN and the engine speed Ne. At step 702, the main fuel injection cam angle based on the top dead center, that is, the top dead center reference main fuel injection cam angle TMFIN, and the fuel injection valve operation delay time TD as a function of the common rail internal pressure Pc are fetched.

In step 703, the top dead center reference main fuel injection cam angle TMFIN is set to the rotation speed pulse counter CN.
The reference point-based main fuel injection cam angle TTM based on the cam angle whose ENO count value is "0" is converted by the following formula. FIG. 21 is an explanatory diagram of the conversion method, in which the horizontal axis represents the cam angle and the vertical axis represents the engine speed pulse Ne.

TTM = 60-TMFIN Here, "60" is the cam angle from the rotation speed detection reference point to the top dead center. Next, at step 704, the reference point reference main fuel injection cam angle TTM is divided by 15 corresponding to the cam angle of one cycle of the engine speed pulse Ne, the quotient being the main fuel injection reference value CNEM, and the remainder being the main fuel. The extra injection angle is TREM.

CNEM = [TTM / 15] TREM = TMFIN−CNEM · 15 Here, [a] represents the integer part of a. In step 705, the main fuel injection margin angle TREM is converted into the main injection margin time TTMF.

TTMF = (TREM / 30) T30-TD Here, "T30" is the time required to rotate the cam angle by 30 degrees. FIG. 8 is a flowchart of a top dead center reference main fuel injection cam angle calculation routine for calculating the top dead center reference main fuel injection cam angle TMFIN fetched in step 701 of the main fuel injection setting process. Rotational speed Ne and main fuel injection amount QM calculated in the main fuel injection energization time calculation routine
Take in the FIN.

In step 802, the top dead center reference main fuel injection cam angle TMFIN is obtained as a function of the engine speed Ne and the main fuel injection amount QMFIN. FIG. 9 is a graph for determining the top dead center reference main fuel injection cam angle TMFIN, where the horizontal axis represents the engine speed Ne and the vertical axis represents the top dead center reference main fuel injection cam angle TMFIN. The parameter is the main fuel injection amount QMFIN.

FIG. 10 is a flow chart of a fuel injection valve operation delay time calculation routine for calculating the fuel injection valve operation delay time TD. In step 1001, the common rail internal pressure Pc is read, and in step 1002 it is calculated as a function of the common rail internal pressure Pc. The fuel injection valve operation delay time TD is calculated. FIG. 11 is a graph for determining the fuel injection valve operation delay time TD, in which the abscissa represents the common rail internal pressure Pc,
The ordinate represents the fuel injection valve operation delay time TD.

FIG. 12 is a flowchart of the first after-fuel injection setting process executed in step 603 of the second fuel injection valve control routine shown in FIG. FIG. 21 is an explanatory diagram of the conversion method, in which the horizontal axis represents the cam angle and the vertical axis represents the engine speed pulse Ne. That is, at step 1201, the top dead center reference after fuel injection cam angle TPFIN as a function of the main fuel injection amount QMFIN and the engine speed Ne.
In step 1202, the fuel injection valve operation delay time TD as a function of the common rail internal pressure Pc is fetched.

In step 1203, the top dead center reference after fuel injection cam angle TPFIN is set to the first reference point reference after fuel injection cam angle TT with the cam angle at which the count value of the rotation speed pulse counter CNENO is "0" as a reference.
Convert to P1 by the following formula. TTP1 = 60 + TPFIN Next, at step 1204, the first reference point reference after fuel injection cam angle TTP1 is set to the engine speed pulse N
Then, the quotient is divided into the first after-fuel injection reference value CNEP1 and the remainder is the first after-fuel injection margin angle TP1REM.

CNEP1 = [TTP1 / 15] TP1REM = TPFIN-CNEP1.15 In step 1205, the first after-fuel injection margin angle TP1REM is set to the first after-injection margin time TTP.
Convert to F1. TTPF1 = (TP1REM / 30) · T30−TD The second after-fuel injection setting process executed in step 604 of the second fuel injection valve control routine shown in FIG. 6 is the same as the first after-fuel injection setting process. It is the same.

FIG. 22 is a top dead center reference after fuel injection cam angle calculation routine for calculating the top dead center reference after fuel injection cam angle TPFIN which is fetched in step 1201 of the first after fuel injection setting process shown in FIG. In the flowchart, in step 2201, the engine speed Ne and the main fuel injection amount QMFIN calculated in the main fuel injection energization time calculation routine are fetched.

In step 2202, the top dead center reference after fuel injection cam angle TPFIN is obtained as a function of the engine speed Ne and the main fuel injection amount QMFIN. FIG.
Is a flow chart of a main fuel injection energization time calculation routine for calculating the main fuel injection energization time TQM. In step 1301, the engine speed Ne, the accelerator opening ACC and the common rail internal pressure Pc are read.

In step 1302, the engine speed N
The main fuel injection amount QMFIN is obtained as a function of e and the accelerator opening degree ACC. In step 1303,
The main fuel injection energization time TQM is obtained as a function of the main fuel injection amount QMFIN and the common rail internal pressure Pc. FIG. 14 is a graph for determining the main fuel injection amount QMFIN, in which the horizontal axis represents the engine speed Ne and the vertical axis represents the main fuel injection amount QMFIN. The parameter is the accelerator opening ACC.

FIG. 15 is a graph for determining the main fuel injection energization time TQM. The horizontal axis shows the main fuel injection amount QMFIN and the vertical axis shows the main fuel injection energization time TQM. The parameter is the common rail internal pressure Pc. FIG. 16 is a flowchart of an after fuel injection energization time calculation routine for calculating the after fuel injection energization time TQP.
e, common rail internal pressure Pc, main fuel injection amount QMF
IN and top dead center reference after fuel injection cam angle TPF
Take in IN.

In step 1602, it is determined whether or not the top dead center reference after fuel injection cam angle TPFIN is less than or equal to a predetermined threshold value χ, and if a positive determination is made, the process proceeds to step 1603. In step 1603,
The after-fuel injection amount QPFIN is obtained as a function of the engine speed Ne and the main fuel injection amount QMFIN.

In step 1604, the after fuel injection energization time TQP is obtained as a function of the after fuel injection amount QPFIN and the common rail internal pressure Pc. If a negative decision is made in step 1602, the operation proceeds to step 1605 to reset the after fuel injection energization time TQP.
This is to prevent the fuel injected by the after-fuel injection from being completely burned and discharged as unburned gas when the after-fuel injection becomes extremely slow, resulting in an increase in hydrocarbons. .

The graph for determining the after fuel injection energization time TQP is substantially the same as the graph for determining the main fuel injection energization time TQM shown in FIG. FIG. 17 is an explanatory diagram of the calculation process of the fuel injection valve energization time and the fuel injection valve energization time, which shows the main fuel injection reference value CN
The case where EM is "2" or "3" and the first after-fuel injection reference value CNEP1 is "6" or "8" is shown.

FIG. 18 is a timing chart for explaining the operation of the pressure-accumulation type fuel injection device according to the present invention, in which the horizontal axis represents the rotary cam angle (CA). The vertical axis indicates the rotation speed pulse from the top, the count value of the rotation speed pulse counter CNENO,
The count value of the cylinder counter CCYLN, the second after-fuel injection reference value CNEP2, the first after-fuel injection reference value CNEP1, the number obtained by adding 8 to the count value of the rotation speed pulse counter CNENO, the main fuel injection reference value CNE
M, fuel injection valve drive pulse PULS and fuel injection needle lift LIFT.

That is, for the # 1 cylinder whose cylinder counter CCYLN is "1", the rotational speed pulse counter CNEN of the # 6 cylinder whose cylinder counter CCYLN is "6" is shown.
A main fuel injection reference value CNEM, a main fuel injection surplus time TTMF, and a first after-fuel injection reference value CNEP1, which are determined by a fuel injection valve control routine shown in FIG. The main fuel injection timing and the after fuel injection timing are determined based on the first after fuel injection surplus time TTPF1, and the first fuel injection valve control routine shown in FIG. 4 and the second fuel injection valve control routine shown in FIG. The main fuel injection and the after fuel injection are executed based on

Rotation speed pulse counter C in cylinder # 1
When the count value of NENO becomes “6”, the main fuel injection reference value CNEM for the # 2 cylinder, the main fuel injection surplus time TTMF, and the second after fuel injection reference value CN
EP2 and the second after-fuel injection surplus time TTPF2 are determined. In the above example, when the state quantity representing the operating state is equal to or more than a predetermined threshold value, the specific operation is performed, but the change rate of the state amount representing the operating state is equal to or more than the threshold value. In some cases, it may be a specific operation.

It is also possible to control execution of after-fuel injection by turning on / off a switch that can be operated by the driver. Furthermore, in the above-described embodiment, the number of after-fuel injections is one, but it may be performed a plurality of times.

[0049]

According to the pressure-accumulation type fuel injection device of the present invention, in a diesel engine with a supercharger, after the fuel injection in the expansion stroke in addition to the main fuel injection when the engine is in a specific operating state. Is done to increase the exhaust gas pressure. Therefore, the after-fuel injection increases the driving force of the exhaust turbine 256 by δp as shown by the broken line in the cycle diagram of FIG. 20, and it is possible to increase the supercharging pressure without additionally installing an auxiliary device.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of a pressure accumulation type fuel injection device.

FIG. 2 is a configuration diagram of an embodiment of a pressure accumulation type fuel injection device according to the present invention.

FIG. 3 is a flowchart of a specific operation state detection routine.

FIG. 4 is a flowchart of a first fuel injection valve control routine.

FIG. 5 is a flowchart of after-fuel injection timer setting processing.

FIG. 6 is a flowchart of a second fuel injection valve control routine.

FIG. 7 is a flowchart of a main fuel injection setting process.

FIG. 8 is a flowchart of a top dead center reference main fuel injection cam angle calculation routine.

FIG. 9 is a graph for determining a top dead center reference main fuel injection cam angle.

FIG. 10 is a flowchart of a fuel injection valve operation delay time calculation routine.

FIG. 11 is a graph for determining a fuel injection valve operation delay time.

FIG. 12 is a flowchart of first after-fuel injection setting processing.

FIG. 13 is a flowchart of a main fuel injection energization time calculation routine.

FIG. 14 is a graph for determining a main fuel injection amount.

FIG. 15 is a graph for determining a main fuel injection energization time.

FIG. 16 is a flowchart of an after fuel injection energization time calculation routine.

FIG. 17 is an explanatory diagram of a calculation process of a fuel injection valve energization time and energization time.

FIG. 18 is a timing chart for explaining the operation of the pressure accumulation type fuel injection device according to the present invention.

FIG. 19 is a schematic view of a supercharged intake device.

FIG. 20 is a cycle diagram of a diesel engine.

FIG. 21 is an explanatory diagram of a process of calculating a fuel injection valve energization time and an energization time.

FIG. 22 is a flowchart of an after fuel injection timing calculation routine.

[Explanation of symbols]

 201 ... Diesel engine 202a-f ... Fuel injection valve 203 ... Common rail 204a-f ... Injection control solenoid valve 205 ... Fuel supply pipe 206 ... Check valve 207 ... High pressure fuel pump 208 ... Fuel tank 209 ... Low pressure fuel pump 210 ... Discharge Quantity control device 211 ... Pressure sensor 212 ... Rotation speed sensor 213 ... Accelerator opening sensor 214 ... Cooling water temperature sensor 215 ... Electronic control device (ECU)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeshi Takahashi 1 Toyota-cho, Toyota-shi, Aichi Toyota Automobile Co., Ltd.

Claims (2)

[Claims] 1. A specific operating state detecting means (11) for detecting that the diesel engine with a supercharger is in a specific operating state.
And a fuel injection mode determination means for determining whether or not an operation state in which after-fuel injection is to be executed in addition to main fuel injection is performed when the specific operation state amount is detected by the specific operation state detection means (11). (12) and main fuel injection execution means (13) for executing main fuel injection in the compression stroke when the fuel injection mode determination means (12) determines that the operating state in which after fuel injection is not to be performed is determined. When the fuel injection mode determination means (12) determines that the vehicle is in an operating state in which after fuel injection should be performed, after fuel injection is executed in the expansion stroke in addition to the main fuel injection by the main fuel injection execution means. An after-fuel injection executing means (14); 2. The after-fuel injection execution means (14)
2. The pressure-accumulation fuel injection device according to claim 1, further comprising after-fuel injection stopping means for stopping the after-fuel injection when the after-fuel injection is performed after a predetermined time.