JP2003074397A - Accumulator type fuel injection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure the same startability as in normal time, even when a common rail pressure sensor causes failure, by improving boosting performance of common rail pressure at engine starting time when the common rail pressure sensor causes failure. SOLUTION: At engine starting time when the common rail pressure sensor causes failure, current-carrying time can be imparted long to a coil of a solenoid valve of a high pressure supply pump even if the common rail pressure sensor causes failure by controlling a delivery quantity of fuel to a common rail from a delivery port of the high pressure supply pump on the basis of exclusive second starting time common rail pressure (PSTAPCF) set higher than ordinary first starting time common rail pressure (PSTA) when an engine speed (NE) is low. Thus, even when the engine speed (NE) is low, since the delivery quantity of the fuel is increased to the common rail from the delivery port of the high pressure supply pump, the boosting performance of the common rail pressure is improved.

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 equipped with feedback control means for feedback-controlling the discharge amount of fuel from a high-pressure supply pump to a common rail, and more particularly to a pressure-accumulation fuel injection device. The present invention relates to a method for controlling the discharge amount of fuel from a high-pressure supply pump to a common rail when starting a diesel engine.

[0002]

2. Description of the Related Art Conventionally, in a diesel engine equipped with a pressure accumulating fuel injection device, a method of controlling the discharge amount of fuel from a high-pressure supply pump to a common rail at the time of engine start is such that a pump phase becomes clear and a predetermined common rail is used. Until the engine pressure rises above the pressure or the engine speed rises above the specified rotation speed, the amount of fuel discharged from the high-pressure supply pump to the common rail is adjusted during the fuel pressure stroke from the pump cam bottom to the pump cam top. A technique disclosed in Japanese Patent Laid-Open No. 2000-18052 is known in which the boosting property of the common rail pressure is improved by repeating the energization ON time and the energization OFF time to the electromagnetic coil of the measuring solenoid valve. Further, there is also known a technique in which, when the common rail pressure sensor fails, the target common rail pressure is replaced with the actual common rail pressure to limit the output of the engine so that the engine can be operated.

[0003]

However, since the actual common rail pressure cannot be detected when the engine is started when the common rail pressure sensor fails, the above means for improving the boosting property cannot be used. As shown in the timing chart, the time from the turning on of the starter switch to the completion of engine starting after cranking (T
There is a problem that b) becomes long. Here, FIG.
In, NPC is the actual common rail pressure, PFIN is the target common rail pressure, and NE is the engine speed. Also, some vehicles equipped with an engine employ an automatic engine starting system, and depending on the setting of the automatic engine starting system, there is a problem that the engine cannot be started at all when the common rail pressure sensor fails. It could have occurred.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the common rail pressure boosting characteristic at the time of engine start when the fuel pressure detecting means is abnormal so that even when the fuel pressure detecting means is out of order, the starting performance is the same as in the normal state. An object of the present invention is to provide a pressure-accumulation fuel injection device that can secure the above.

[0005]

According to the first aspect of the invention, the actual common rail pressure detected by the fuel pressure detecting means when the engine is started when the fuel pressure detecting means is normal is determined by the rotational speed detecting means. The amount of fuel discharged from the high-pressure supply pump to the common rail is controlled so as to substantially match the first starting common rail pressure set according to the detected engine speed and the engine temperature detected by the engine temperature detection means. ing.

Further, when the engine is started when the fuel pressure detecting means is abnormal, the second starting common rail pressure set higher than the first starting common rail pressure when the engine speed detected by the rotation speed detecting means is low. The fuel discharge amount from the high-pressure supply pump to the common rail is controlled based on the above. As a result, the amount of fuel discharged from the high-pressure supply pump to the common rail can be increased even when the engine speed is low, so the performance of boosting the common rail pressure of the fuel accumulated in the common rail can be improved. As a result, even when the engine is started when the fuel pressure detecting means fails, it is possible to obtain substantially the same starting performance as when the fuel pressure detecting means is normal.

According to the second aspect of the present invention, when the engine is started when the fuel pressure detecting means is abnormal, when the engine rotational speed detected by the rotational speed detecting means is low, it is higher than the first starting common rail pressure. By controlling the energization time to the electromagnetic coil of the discharge control solenoid valve based on the set second common rail pressure at the time of starting, when the engine speed is low, the electromagnetic coil of the discharge control solenoid valve is energized. The time can be lengthened. This allows
Even when the engine speed is low, the amount of fuel discharged from the high-pressure supply pump to the common rail can be increased, so that the performance of boosting the common rail pressure of the fuel accumulated in the common rail can be improved.

According to the third aspect of the invention, the second starting common rail pressure is set to be much higher than the first starting common rail pressure as the engine rotation speed detected by the rotation speed detecting means is lower. Further, it is characterized in that it is set so that it converges to the first starting common rail pressure as the engine rotation speed detected by the rotation speed detection means increases. As a result, when the engine is started when the fuel pressure detecting means is abnormal, the common rail pressure of the fuel accumulated in the common rail is made to follow the first starting common rail pressure when the engine is started normally when the fuel pressure detecting means is normal. Therefore, even when the engine is started when the fuel pressure detecting means fails, it is possible to obtain a starting performance that is substantially the same as when the fuel pressure detecting means is normal.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION [Structure of Embodiment] An embodiment of the present invention will be described based on an embodiment with reference to the drawings. here,
FIG. 1 is a diagram showing an overall configuration of a common rail fuel injection device.

The common rail type fuel injection device of this embodiment corresponds to the pressure accumulation type fuel injection device of the present invention, and is, for example, a multi-cylinder diesel engine (hereinafter abbreviated as engine).
A plurality of injectors 2 that inject high-pressure fuel into the combustion chamber of each cylinder 1, a common rail 3 that is a kind of surge tank that stores high-pressure fuel, and a known low-pressure supply pump (feed pump) that pumps fuel from the fuel tank 4. ) 5
A variable discharge type high pressure supply pump (supply pump: hereinafter abbreviated as high pressure supply pump) 6 that pressurizes the fuel sucked through the low pressure supply pump 5 to a high pressure and supplies it to the common rail 3, and injection of a plurality of injectors 2. The electronic control fuel injection system includes an electronic control unit (hereinafter referred to as an ECU) 10 that controls the timing, the injection amount, and the discharge amount of the high-pressure supply pump 6.

The injector 2 has a well-known structure, is connected to the downstream ends of the fuel pipes communicating with the common rail 3, and has a fuel injection nozzle for injecting and supplying high pressure fuel into the combustion chamber of each cylinder of the engine 1. An injection period control solenoid valve (hereinafter, abbreviated as solenoid valve) 8 for driving the fuel injection nozzle. And the injector 2
Is controlled by a control signal output from the ECU 10 via an injector drive circuit (not shown). While the solenoid valve 8 is open, the high pressure fuel accumulated in the common rail 3 is used in the engine 1 Is injected and supplied into the combustion chamber of each cylinder.

The common rail 3 includes a discharge port of a high pressure supply pump 6 for discharging high pressure fuel, a discharge valve 11, and a fuel pipe 1.
It is connected via 2. Further, the common rail 3 is provided with a pressure limiter (not shown) for preventing the internal common rail pressure from exceeding a predetermined limit pressure. Further, the common rail 3 is provided with a common rail pressure sensor 24 for detecting the actual injection pressure supplied from each injector 2 to the engine 1, that is, the actual common rail pressure (NPC).

The high-pressure supply pump 6 operates so as to suck and pressurize the fuel into the plunger chamber, and to discharge the high-pressure fuel corresponding to the target common rail pressure (PFIN) commanded by the ECU 10 to the common rail 3. And
The high-pressure supply pump 6 pressurizes the fuel in the fuel tank 4 by the rotation of the crankshaft of the engine 1 (plunger chamber).
A low-pressure supply pump 5 for pumping up is built in.
The high-pressure supply pump 6 is provided with a plunger (not shown) for pressurizing the fuel supplied to the plunger chamber by the low-pressure supply pump 5 and sending it as high-pressure fuel to the common rail 3.

A discharge amount control solenoid valve (pump flow control valve: hereinafter abbreviated as solenoid valve) 7 for controlling the discharge pressure (discharge amount, pumping amount) of fuel is attached to the high-pressure supply pump 6. ing. The solenoid valve 7 is controlled by a control signal output from the ECU 10 via a pump drive circuit (not shown), and by varying the valve opening rate of the solenoid valve 7, the fuel discharge pressure to the common rail 3 is changed. (Discharge amount, pumping amount) is adjusted. Thereby, the fuel pressure accumulated in the common rail 3, that is, the actual common rail pressure can be changed. The electromagnetic valve 7 opens when the electromagnetic coil is energized, and the longer the energization ON time of the electromagnetic coil from the ECU 10, the larger the fuel discharge pressure (discharging amount, pumping amount) to the common rail 3. To work.

Next, the ECU 10 will be briefly described with reference to FIG. The ECU 10 has a CPU for performing control processing and arithmetic processing, an R for storing various programs and data.
A microcomputer having a well-known structure including functions of an OM, a RAM, an input circuit, an output circuit, a detection circuit of various sensors, a failure diagnosis circuit of various sensors, a power supply circuit, an injector drive circuit, a pump drive circuit, and the like is provided. Has been. The sensor signals from the various sensors are A /
It is configured so that it is A / D converted by the D converter and then input to the microcomputer.

Here, as a basic sensor that outputs a detection signal to the ECU 10, a rotation speed sensor (rotation speed detection means) 21 (which is a high-voltage supply) for detecting the rotation speed (NE: engine speed) of the engine 1 is used. It may be built in the pump 6), an accelerator opening sensor (operating state detection means) 22 for detecting the depression amount of the accelerator pedal (hereinafter referred to as accelerator opening), the temperature of cooling water of the engine 1 (THW: engine There is a cooling water temperature sensor (engine temperature detecting means) 23 or the like for detecting a cooling water temperature. In addition to the accelerator opening sensor 22, a cylinder discrimination sensor 25, a target injection amount determining means for calculating a target injection amount (QFIN),
You may use the driving | running state detection means which detects the driving | running state of the engine 1, such as an injection timing sensor, an intake air pressure sensor, and an intake air temperature sensor. In addition to the cooling water temperature sensor 23, an engine temperature detecting means for detecting the engine temperature such as a fuel temperature sensor 26 and an engine temperature sensor may be used.

The ECU 10 determines the optimum injection timing and injection amount (= injection period) according to the operating state of the engine 1,
The solenoid valve 8 of each injector 2 is driven via an injector drive circuit (EDU) not shown. Ie EC
U10 is the engine cooling water temperature (THW) detected by the cooling water temperature sensor 23 from the engine speed (NE) detected by the rotation speed sensor 21 and the accelerator opening (ACCP) detected by the accelerator opening sensor 22. The target injection amount (QFIN) is calculated in consideration of the correction of, and in order to achieve the calculated target injection amount (QFIN), in accordance with the injector energization signal calculated from the actual common rail pressure (NPC) for each operating state. By driving the solenoid valve 8 of each injector 2 respectively.
Is driven.

The ECU 10 corresponds to the first start-up discharge amount control means and the second start-up discharge amount control means of the present invention, and of the high pressure supply pump 6 via a pump drive circuit (EDU) not shown. The solenoid valve 7 is driven. That is, E
The CU 10 has a high-pressure supply pump 6 so as to have an optimum common rail pressure determined by the engine speed (NE) detected by the rotation speed sensor 21 and the accelerator opening (ACCP) detected by the accelerator opening sensor 22. Is configured to output a control signal to the solenoid valve 7.

Further, the ECU 10 determines that the actual common rail pressure (NPC) detected by the above-mentioned common rail pressure sensor 24 is the engine parameter such as the target injection amount (QFIN), the engine speed (NE), the engine cooling water temperature (THW) and the like. Target common rail pressure (PF
IN), a program (feedback control means) for feedback controlling the discharge pressure (discharge amount, pumping amount) of fuel from the discharge port of the high-pressure supply pump 6 to the common rail 3 is installed. There is. Here, the common rail pressure sensor 24 is attached to the common rail 3 and is a fuel pressure detection means (common rail pressure detection means) that detects the fuel pressure accumulated in the common rail 5, that is, the actual common rail pressure (NPC). .

Note that the ECU 10 turns on the ignition switch by the vehicle occupant for the purpose of starting the engine 1.
When the crankshaft of the engine 1 is cranked at a speed equal to or higher than the required minimum rotation speed by further energizing the starter, as shown in FIG. 2, the engine speed detected by the rotation speed sensor 21 ( NE) and the engine coolant temperature (TH) detected by the coolant temperature sensor 23.
The optimum injection starting pressure (first
A first starting common rail pressure determining means for calculating a starting common rail pressure) is provided. Here, the lower the engine cooling water temperature (THW) is, the higher the starting target common rail pressure is set.

Further, the microcomputer is provided with a failure diagnosis circuit for self-diagnosing a failure (abnormal state) of the common rail pressure sensor 24 and a failure of its detection circuit. Therefore, the ECU 10 uses the common rail pressure sensor 2
4, when the engine is started when a failure occurs in the detection circuit 4 or its detection circuit, as shown in FIG. 2, the actual common rail pressure (actual common rail pressure) is increased according to the engine speed (NE) detected by the rotation speed sensor 21. It has a second starting common rail pressure determining means for calculating an optimum injection starting pressure (second starting common rail pressure) for improving the property.

Here, the method of calculating the target common rail pressure (PFIN) by the ECU 10 of the present embodiment uses the basic common rail pressure map (MPBASE1) of FIG. 2 if it is not at the time of starting (normal operating condition). A basic common rail pressure (PBASE) obtained from the target injection amount (QFIN), the engine speed (NE) and the engine cooling water temperature (THW) is calculated as the target common rail pressure (PFIN). When the engine is started, the first common rail pressure (PSTA) obtained from the engine speed (NE) and the engine coolant temperature (THW) using the first common rail pressure map (MPSTA) shown in FIG. Is calculated as the target common rail pressure (PFIN). When the failure diagnosis circuit determines that the common rail pressure sensor 24 or its detection circuit has a failure, the target is the second starting common rail pressure (PSTAPCF) when the common rail pressure sensor is abnormal, which is obtained only from the engine speed (NE). Common rail pressure (PFIN)
And

The map selecting means 31 shown in FIG.
Selects the basic common rail pressure (PBASE) as the target common rail pressure (PFIN) when XSTART (starting state flag) is ON (1).
When RT (starting state flag) is OFF (0), the first starting common rail pressure (PSTA) or the second starting common rail pressure (PSTAPCF) is selected as the target common rail pressure (PFIN). .
Then, the map selecting means 32 shown in FIG.
PC (common rail pressure sensor error flag) is ON
At the time of (1), the second common rail pressure at start (PSTAPCF) when the common rail pressure sensor is abnormal is selected. When XLHSPC (common rail pressure sensor abnormality flag) is OFF (0), the first common rail pressure at start is selected. It is configured to select (PSTA).

[Control Method of Embodiment] Next, a control method of the common rail pressure at the time of starting of the present embodiment will be briefly described with reference to FIGS. 1 to 5. 3 and 4 are ECUs
6 is a flowchart showing a method of calculating the discharge amount of the high-pressure supply pump according to.

First, as shown in the flow chart of FIG. 3, whether or not the starting state (XSTART = 1) is determined from the ON (IG.ON) signal of the ignition switch and the ON (ST.ON) signal of the starter switch. It is determined (step S1). When the determination result is NO, as shown in the flowchart of FIG. 4, the actual common rail pressure (NPC) is calculated from the output value of the common rail pressure sensor 24 (step S2). Next, the engine speed (N
E), target injection amount (QFIN), engine cooling water temperature (T
HW) and basic common rail pressure map (MPB in Fig. 2)
Basic common rail pressure (PBAS) based on ASE1)
E) is calculated (step S3). Next, the basic common rail pressure (PBASE) is changed to the target common rail pressure (PFI).
N) (step S4).

Subsequently, feedback (FB) control of the common rail pressure is performed. That is, the actual common rail pressure (NPC) detected by the common rail pressure sensor 24.
The feedback control of the discharge amount of the high-pressure supply pump 6 is performed so that the value becomes equal to the target common rail pressure (PFIN). Specifically, the pressure deviation value (ΔPC) between the actual common rail pressure (NPC) and the target common rail pressure (PFIN) is calculated (step S5). Next, the feedback amount for pressure feeding of the high-pressure supply pump 6 is calculated from the pressure deviation value (ΔPC) (step S6). Next, the basic pumping amount is calculated from the target injection amount (QFIN) and the target common rail pressure (PFIN) (step S7). Next, the fuel discharge amount (pressure feed amount) from the discharge port of the high-pressure supply pump 6 to the common rail 3 is calculated from the basic pressure feed amount and the feedback amount. That is, the energization time to the electromagnetic coil of the electromagnetic valve 7 of the high-pressure supply pump 6 is calculated (step S8).

Further, as shown in the flow chart of FIG. 3, if the decision result in the step S1 is YES, whether or not the common rail pressure sensor 24 or its detection circuit is in failure (abnormality) is determined by the failure diagnosis circuit. judge. That is, it is determined whether or not the output value of the common rail pressure sensor 24 is outside the usage range at the time of engine start (step S9). When the determination result is NO, that is, when the common rail pressure sensor 24 is normal, the actual common rail pressure (NPC) is calculated from the output value of the common rail pressure sensor 24 as shown in the flowchart of FIG. 4 (step S10). Next, the first starting common rail pressure (PSTA) is calculated based on the engine speed (NE), the engine cooling water temperature (THW) and the first starting common rail pressure map (MPSTA) of FIG. 2 (step S11). Next, the first starting common rail pressure (PSTA) is replaced with the target common rail pressure (PFIN) (step S1).
2). Then, the control process of step S5 and subsequent steps is performed.

Further, as shown in the flow chart of FIG. 3, when the determination result of step S9 is YES, that is, when the common rail pressure sensor 24 is abnormal, the actual common rail pressure (NPC) is replaced with the target common rail pressure (PFIN). Then, the subsequent control (for example, EGR control) is performed (step S13). Next, the engine speed (NE) and the second starting common rail pressure map (M
The second starting common rail pressure (PSTAPCF) is calculated based on PSTAPCF) (step S14). Next, the second starting common rail pressure (PSTAPCF) is replaced with the target common rail pressure (PFIN) (step S15). Next, the discharge amount (pressure feed amount) of the fuel from the discharge port of the high-pressure supply pump 6 to the common rail 3 is calculated. That is, the energization time to the electromagnetic coil of the electromagnetic valve 7 of the high-pressure supply pump 6 is calculated (step S16).

[Characteristics of Embodiment] Here, in the common rail type fuel injection device of the present embodiment, the common rail pressure sensor 2 is operated by the failure diagnosis circuit of the common rail pressure sensor 24.
4 or the detection circuit is faulty, when the common rail pressure is replaced with the target common rail pressure and the engine is operated, the boosting performance of the common rail pressure is increased.
In order to give a longer energization time to the electromagnetic coil of the electromagnetic valve 7 of the high-pressure supply pump 6, a dedicated dedicated rail pressure higher than the normal first starting common rail pressure (PSTA) is set when the engine speed (NE) is low. Common rail pressure (P
The discharge amount of the fuel from the discharge port of the high-pressure supply pump 6 to the common rail 3 (pressure feed amount), that is, the energization time to the electromagnetic coil of the solenoid valve 7 of the high-pressure supply pump 6 is controlled based on STAPCF). .

Specifically, when the engine is started when the common rail pressure sensor 24 fails, the second starting common rail pressure (PS) which is different from the normal rail pressure sensor 24 when the common rail pressure sensor 24 is normal.
High pressure supply pump 6 by setting TAPCF)
The energization time of the electromagnetic coil of the electromagnetic valve 7 can be extended. This makes it possible to increase the amount of fuel discharged from the discharge port of the high-pressure supply pump 6 to the common rail 3 (pressure feed amount), so that the actual boosting performance of the common rail pressure can be improved. Therefore, it is possible to secure the engine starting performance equivalent to that when the common rail pressure sensor 24 is normal.

According to the second common rail pressure map at starting when the common rail pressure sensor is abnormal in this embodiment (see FIG. 5), the engine speed (NE) detected by the rotation speed sensor 21 is the first predetermined value. When the following is low, the second starting common rail pressure (PSTAPCF), which is significantly higher than the first starting common rail pressure (PSTA) when the common rail pressure sensor 24 is normal, is equal to the target common rail pressure (P
FIN). As a result, even if the common rail pressure sensor 24 is out of order, the energization time of the electromagnetic coil of the electromagnetic valve 7 of the high-pressure supply pump 6 can be extended, so that the high-pressure supply pump 6 operates even when the engine speed is low. The amount of fuel discharged from the discharge port to the common rail 3 (pressure feed amount) can be increased. As a result, the actual boosting performance of the common rail pressure can be improved.

When the engine speed (NE) rises and becomes higher than the second predetermined value, the common rail pressure sensor 24 at the first starting common rail pressure (PST) when the common rail pressure sensor 24 is normal.
Second common rail pressure (PSTAP) which is almost the same as A)
CF) = target common rail pressure (PFIN) is set. As a result, when the starter switch is turned on to crank the engine 1 and the start of the engine 1 is completed, the target common rail pressure (PFIN) of the common rail pressure sensor 24 converges to the target common rail pressure (PFIN). It is possible to suppress the phenomenon that the actual common rail pressure overshoots or undershoots significantly with respect to PFIN), and also suppresses the generation of black smoke (smoke).

When the engine speed (NE) detected by the rotation speed sensor 21 is between the first predetermined value and the second predetermined value, the gradient for gradually decreasing the target common rail pressure (PFIN) is: The engine speed (NE) detected by the rotation speed sensor 21 is abruptly inclined from the first predetermined value to the middle, and the engine speed (NE) detected by the rotation speed sensor 21 is changed from the middle to the second predetermined value. Is slowly sloping up to.

That is, the common rail pressure (P
STACF) = target common rail pressure (PFIN) is
Since the lower the engine speed (NE) is, the larger the engine speed is, and the higher the engine speed is, the lower the engine speed is. Therefore, the common rail pressure sensor 24 is controlled so as to increase the actual common rail pressure in a pseudo manner. To be done. Even when the common rail pressure sensor 24 fails, the engine 1 is started by controlling the fuel discharge amount (pressure feed amount) from the discharge port of the high-pressure supply pump 6 to the common rail 3 as described above. Therefore, pseudo common rail pressure control can be performed. As a result, even in a vehicle that employs the automatic engine starting system, the engine 1 can be started when the common rail pressure sensor 24 fails.

As a result, the common rail pressure sensor 24
As shown in the timing charts of FIGS. 6 and 7, when the engine is started when a failure occurs, the actual common rail pressure (NPC: see FIG. 7) when the common rail pressure sensor 24 is abnormal is when the common rail pressure sensor 24 is normal. The actual common rail pressure (NPC: refer to FIG. 6) is increased at a gradient, so the time Ta (<T
b) can be significantly shortened as compared with the conventional technique (see FIG. 8). Here, in FIGS. 6 and 7, NP
C is the actual common rail pressure, PFIN is the target common rail pressure, and NE is the engine speed.

[Modification] In this embodiment, the normal first starting common rail pressure (PSTA) = target common rail pressure (PFIN) is determined according to the engine speed (NE) and the engine coolant temperature (THW). However, since the rotation speed of the starter becomes slower as the battery voltage decreases, the battery voltage decreases as the ambient temperature in the engine room, which is affected by the engine temperature, decreases. For this reason, the engine speed and the battery voltage have a correlation with the engine temperature. Therefore, using either one, the normal first starting common rail pressure (PSTA) = target common rail pressure (P
FIN) may be determined.

In this embodiment, the dedicated second common rail pressure (PSTA) at the time of starting (PSTA) is set according to only the engine speed (NE).
Although the example in which PCF) = target common rail pressure (PFIN) is determined has been described, for the reasons described above, the second starting common rail pressure (PSTAPPC) dedicated for engine speed and battery voltage or engine temperature is used. (PFIN) may be determined.

In this embodiment, the common rail pressure sensor 24
Is attached directly to the common rail 3 to detect the fuel pressure accumulated in the common rail 3 (actual common rail pressure). The fuel pressure detection means is provided from the plunger chamber of the high pressure supply pump 6 to the fuel passage in the injector 2. The fuel pressure discharged from the plunger chamber of the high-pressure supply pump 6 may be detected by mounting the fuel pipe or the like between the two.

In this embodiment, when the failure diagnosis circuit of the ECU 10 determines whether or not the common rail pressure sensor 24 or its detection circuit has a failure (abnormality), the output value of the common rail pressure sensor 24 at the time of engine start. I am trying to determine whether it is out of the usable range.
When determining whether or not the common rail pressure sensor 24 or its detection circuit is in failure by the failure diagnosis circuit of the CU 10, whether or not the output value of the common rail pressure sensor 24 is higher than the use range at the time of engine start, or It may be possible to determine whether or not it is below the usage range when the engine is started.

In this embodiment, an example in which the discharge amount controlling solenoid valve 7 for changing (adjusting) the discharge amount of fuel from the plunger chamber (pressurizing chamber) of the high pressure supply pump 6 to the common rail 3 is provided has been described. A suction amount control solenoid valve for changing (adjusting) the suction amount of the fuel sucked into the plunger chamber (pressurizing chamber) of the high-pressure supply pump 6 may be provided. It should be noted that the discharge amount control solenoid valve 7 or the suction valve operates such that the longer the energization ON time of the electromagnetic coil of the discharge amount control solenoid valve 7 or the suction amount control solenoid valve, the larger the fuel discharge amount or the suction amount. A high-pressure supply pump 6 may be provided with a quantity control solenoid valve, and the shorter the energization ON time of the discharge quantity control solenoid valve 7 or the solenoid coil of the suction quantity control solenoid valve, the shorter the fuel discharge quantity or suction quantity. The discharge amount control solenoid valve 7 or the suction amount control solenoid valve that operates so as to increase the pressure may be provided in the high-pressure supply pump 6.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an overall configuration of a common rail fuel injection device (embodiment).

FIG. 2 is a block diagram showing a method of calculating a target common rail pressure by an ECU (embodiment).

FIG. 3 is a flowchart showing a method of calculating a discharge amount of a high-pressure supply pump by an ECU (embodiment).

FIG. 4 is a flowchart showing a method of calculating a discharge amount of a high-pressure supply pump by an ECU (embodiment).

FIG. 5 is a characteristic diagram showing a second common rail pressure map at the time of starting (Example).

FIG. 6 is a timing chart showing changes in the actual common rail pressure, the target common rail pressure, and the engine speed when the common rail pressure sensor is normal (Example).

FIG. 7 is a timing chart showing changes in the actual common rail pressure, the target common rail pressure, and the engine speed when the common rail pressure sensor is abnormal (Example).

FIG. 8 is a timing chart showing changes in the actual common rail pressure, the target common rail pressure, and the engine speed when the common rail pressure sensor is abnormal (conventional example).

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 engine 2 injector 3 common rail 6 high pressure supply pump 7 solenoid valve (solenoid valve for discharge amount control) 10 ECU (first start discharge amount control means, second start discharge amount control means) 21 rotation speed sensor (rotation speed detection 22) Accelerator opening sensor (operating state detecting means) 23 Engine cooling water temperature (engine temperature detecting means) 24 Common rail pressure sensor (fuel pressure detecting means)

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Ken Uchiyama             1-1, Showa-cho, Kariya city, Aichi stock market             Inside the company DENSO F-term (reference) 3G066 AA07 AB02 AC09 BA28 BA30                       BA48 BA51 BA69 CB05 CD29                       CE22 DA01 DB01 DB12 DC09                       DC18                 3G084 AA01 BA03 BA13 BA14 CA01                       DA04 DA09 DA26 DA27 DA30                       EB08 EB12 FA13 FA33                 3G301 HA02 HA06 JA03 JA13 JA31                       JB01 JB08 KA01 KA24 LB11                       LB13 LC01 MA11 NA08 NB06                       NB18 NC02 NC04 ND02 ND03                       ND04 NE01 PB08Z PE01Z                       PE08Z PF16Z

Claims (3)

[Claims] 1. A high-pressure supply pump for pressurizing and discharging fuel at a high pressure, (b) a common rail for accumulating high-pressure fuel discharged from the high-pressure supply pump, and (c) pressure for accumulating on the common rail. An injector for injecting high-pressure fuel, (d) a rotation speed detecting means for detecting a rotation speed of an engine equipped with this injector, (e) an engine temperature detecting means for detecting a temperature of the engine, and (f) the above Fuel pressure detection means for detecting the common rail pressure of the fuel accumulated in the common rail; and (g) the actual common rail pressure detected by the fuel pressure detection means at the time of engine startup when the fuel pressure detection means is normal, Depending on the engine rotation speed detected by the speed detection means and the engine temperature detected by the engine temperature detection means First start-time discharge amount control means for controlling the discharge amount of fuel from the high-pressure supply pump to the common rail so as to substantially match the determined first start-time common rail pressure; and (h) the fuel pressure detection means. At the time of engine start at the time of abnormal condition, the high pressure supply is performed based on the second starting common rail pressure set higher than the first starting common rail pressure when the engine speed detected by the rotation speed detecting means is low. A pressure-accumulation type fuel injection device comprising: a second starting discharge amount control means for controlling a discharge amount of fuel from a pump to the common rail. 2. The pressure-accumulation fuel injection device according to claim 1, wherein the high-pressure supply pump is provided with a discharge amount control solenoid valve for changing a discharge amount of fuel from the high-pressure supply pump to the common rail. The discharge amount control solenoid valve is configured such that the discharge amount of fuel to the common rail increases as the energization time of the electromagnetic coil increases, and the second start-time discharge amount control means includes: Based on the second common rail pressure at the time of starting, which is set higher than the first common rail pressure at the time of starting, when the engine speed is low when the engine speed is detected when the engine speed is low. And a time period for energizing an electromagnetic coil of the discharge amount controlling solenoid valve is controlled. 3. The pressure-accumulation fuel injection device according to claim 1, wherein the second starting common rail pressure is the first when the engine rotation speed detected by the rotation speed detecting means is lower. It is set to be much higher than the common rail pressure at startup,
Further, the pressure-accumulation fuel injection device is set so as to converge to the first common rail pressure at the first start as the engine rotation speed detected by the rotation speed detection means increases.