JP2001295685A - Accumulator fuel injector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a common rail type fuel injector, capable of reducing the starting time before complete explosion is obtained at low temperature starting. SOLUTION: When application of an electric current to a starter is started to crank a diesel engine more than a required rotating speed, the optimum injection start pressure (=target pressure) according to the engine cooling water temperature is calculated as the injection start pressure for starting fuel injection to the diesel engine. The current application time command (valve opening command) to respective injectors 1 to 4 is inhibited, until the injection start pressure is increased above the target pressure, whereby fuel injection can be executed at an optimum injection pressure for engine start from the initial stage of injection start. Accordingly, adverse effects, such as lowering of temperature in each combustion chamber of the engine by the fuel injection can be prevented so that in the diesel engine fuel can be readily ignited by heat of air compression, and the time required from the start of fuel injection to the initial explosion can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure accumulating fuel injection device, and more particularly, to accumulating high-pressure fuel discharged from a high-pressure pump in a common rail, and uniformly injecting the fuel into each combustion chamber of a diesel engine. The present invention relates to a common rail fuel injection device capable of applying pressure.

[0002]

2. Description of the Related Art Heretofore, there has been known a pressure-accumulation type fuel injection device in which high-pressure fuel accumulated in a common rail functioning as a kind of surge tank is injected by an injector into a combustion chamber of a diesel engine. Such a pressure-accumulating fuel injection device increases the pressure of fuel pumped from a fuel tank by a high-pressure pump that is driven to rotate by a crankshaft of a diesel engine.

The solenoid valve for adjustment mounted on the high-pressure pump is electronically controlled by a control signal from the ECU to adjust the amount of high-pressure fuel pumped from the high-pressure pump to the common rail via the fuel pipe. , The common rail pressure is changed to a desired injection pressure.

[0004]

However, in the conventional pressure-accumulation type fuel injection device, the optimum injection start pressure for starting the engine differs depending on the engine temperature, but the condition of the injection start pressure that permits the start of the fuel injection is outside. Even when the temperature is low (starting at low temperature), the outside temperature is normal temperature (about 25 ° C)
It is a constant value even at the time (at normal temperature start). Thus, at the time of low-temperature start, as shown in the timing charts of FIGS. 6B and 6D, a pressure value (injection start pressure) which is considerably lower than the optimal injection pressure (target pressure) corresponding to the engine temperature. Start of fuel injection into the combustion chamber of the diesel engine is permitted.

As a result, this fuel injection has an adverse effect such as lowering the temperature of the combustion chamber of the diesel engine,
It becomes difficult to ignite the fuel due to the heat of air compression of the engine, it becomes difficult to start the engine, and it takes time until effective combustion is obtained, as shown in the timing charts of FIGS. 6 (a) and 6 (c). In addition, the time required to obtain the first explosion is extended, and there is a problem that the starting time from the start of energization of the starter to the complete explosion is long.

[0006] In particular, in an extremely cold region where the outside air temperature decreases to -10 ° C or less in winter, the above-mentioned problem becomes more prominent, and the starting time for obtaining a complete explosion becomes longer.
If a vehicle occupant mistakenly judges that an engine has failed,
Operating the starter for a long time causes a problem that the battery is consumed and the battery runs out.

Here, the start of the engine is generally completed with the first explosion, complete explosion, and blow-up. The shorter the time until the complete explosion, the better the startability, and the shorter the time until the blow-up, the faster the response. It is judged to be a good diesel engine. In particular, when the engine friction is large such as at the time of a low temperature start, the startability and the blow-up performance are deteriorated, and it is necessary to improve these.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fuel injection valve which opens the fuel injection valve to start fuel injection at the time of starting the engine, particularly at a low temperature. Provided is a pressure-accumulation type fuel injection device that can reduce the time from the start of fuel injection to effective combustion by setting the start pressure.

[0009]

According to the first aspect of the present invention, the fuel pressure detected by the fuel pressure detecting means rises above the injection pressure optimal for starting the engine determined by the injection start pressure determining means. Until the fuel injection valve opening instruction is prohibited, the fuel injection to the engine is not started at a low temperature start with a pressure value much lower than the optimum injection pressure corresponding to the engine temperature.

Therefore, by starting fuel injection to the engine when the fuel pressure rises above the optimum injection pressure for starting the engine, the time until effective combustion is obtained is shortened, and energization of the starter is started. The start-up time from the start to the complete explosion can be greatly reduced. As a result, even in extremely cold regions, the starting time required to obtain a complete explosion can be reduced, so that the vehicle occupant does not mistakenly determine that the engine has failed, and the time required to energize the starter can be reduced, thereby reducing battery consumption. Battery life can be suppressed.

According to the second aspect of the invention, the optimum injection start pressure for starting the fuel injection at the time of starting the engine is determined by the temperature of the intake air taken into the engine, the temperature of the fuel, the cooling water temperature of the engine, or the temperature of the outdoor air. Any one of the temperatures
By setting at least one, it is possible to improve the startability at the time of low-temperature start. According to the third aspect of the invention, at the start of energization of the starter for starting the engine, any one of the rotation speed of the engine, the battery voltage of the battery supplying power to the starter, or the temperature of the room air is used. By setting at least one, it is possible to improve the startability at the time of low-temperature start. Claim 4
According to the invention described in the above, the injection pressure optimal for starting the engine is such that the lower the engine temperature such as the engine cooling water temperature, the cranking rotational speed or the intake air temperature, the higher the target rail pressure at start. It is characterized by being.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [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 a fuel piping system of a common rail type fuel injection device.

The common rail type fuel injection device of this embodiment corresponds to the accumulator type fuel injection device of the present invention, and has a plurality of cylinders mounted on the combustion chamber of each cylinder of a multi-cylinder diesel engine (hereinafter abbreviated as engine). Fuel injection valves (fuel injection nozzles: hereinafter referred to as injectors) 1 to 4 and a common rail 5 which is a kind of surge tank for accumulating high-pressure fuel
A variable discharge type high pressure pump (hereinafter abbreviated as a high pressure pump) 7 for pressurizing the fuel pumped from the fuel tank 6 and discharging the fuel to the common rail 5, and an electronic device for electronically controlling the plurality of injectors 1 to 4 and the high pressure pump 7. 1 is an electronic control fuel injection system including an electronic control unit (hereinafter referred to as an ECU) 10.

Here, the engine is started when the flywheel of the engine is rotated by a starter (motor for starting the engine) which is rotated by the electric power of the battery at a minimum rotational speed required for starting the engine. When the vehicle occupant turns the ignition switch from the OFF position to the ST position, energization of the starter is started by the ECU (the starter ON signal is turned ON).

A plurality (four in this example) of injectors 1
Reference numerals 4 to 4 denote fuel injection nozzles which are attached to the combustion chambers of the respective cylinders (cylinders) of the engine and inject high-pressure fuel into the respective combustion chambers of the engine. The amount of fuel injected from each of the injectors 1 to 4 to the engine, the fuel injection timing, and the like are controlled by the ECU 10 to control the energization and deactivation of the injection period control solenoid valves (injection period variable means) 11 to 14 as actuators. To be determined.

The common rail 5 is a kind of surge tank for storing high-pressure fuel of a relatively high pressure (common rail pressure of 1000 times or more) (common rail pressure), and is connected to each of the injectors 1 to 4 via a high-pressure pipe 8. ing. The fuel return pipe 9 from each of the injectors 1 to 4, the common rail 5 and the high-pressure pump 7 to the fuel tank 6 is also connected to the pressure limiter 15 so that the common rail pressure in the common rail 5 does not exceed the limit pressure accumulation pressure. It is configured so that pressure can be released.

The high pressure pump 7 has a built-in feed pump (not shown) that rotates with the rotation of the crankshaft of the engine to pump the fuel in the fuel tank 6 through a fuel pipe 17 with a fuel filter 16 interposed therebetween. The feed pump is composed of a supply pump that pressurizes the fuel sucked by the feed pump to pump the high-pressure fuel. This high pressure pump 7
Includes an injection pressure control solenoid valve 1 as an actuator.
9 is attached.

The injection pressure control solenoid valve 19 is provided with an ECU
By being electronically controlled by the control signal from 10,
This is an injection pressure variable unit that changes the injection pressure at which fuel is injected from each of the injectors 1 to 4 into the combustion chamber of the engine by adjusting the amount of high-pressure fuel sent from the high-pressure pump 7 to the common rail 5 via the fuel pipe 18.

The ECU 10 corresponds to the fuel injection control means and the injection start pressure determining means of the present invention. The ECU 10 performs control processing and arithmetic processing, a ROM for storing various control programs and data, and stores input data. RA
M, an input circuit, an output circuit, a power supply circuit, an injector drive circuit (hereinafter, referred to as an EDU) 20, and the like.

The EDU 20 of this embodiment receives a control signal (for example, a control pulse signal) output from the ECU 10, and adjusts the fuel injection timing (valve opening timing) and the fuel injection amount (= injection period) calculated by the ECU 10. The battery voltage of a battery (not shown) is controlled so that the injection period control solenoid valves 11 to 1 of the injectors 1 to 4 are opened and closed accordingly.
4 (supply of electricity) or stop of supply (stop of electricity).

The basic sensors input to the ECU 10 include a rotational speed sensor (operating state detecting means) 21 for detecting the rotational speed of the engine, and an accelerator opening sensor (an accelerator opening) for detecting the amount of depression of an accelerator pedal (accelerator opening). Operating state detecting means) 22, an intake air temperature sensor 23 for detecting the temperature of intake air sucked by the engine, and a return pipe 9
There are a fuel temperature sensor 24 for detecting the temperature of the fuel inside, a cooling water temperature sensor (engine temperature detecting means) 25 for detecting the cooling water temperature of the engine, and the like.

Further, a fuel pressure sensor (fuel pressure detecting means) 26 for detecting a fuel pressure (injection pressure, common rail pressure) of the high-pressure fuel accumulated in the common rail 5, a rotation angle of the engine crankshaft, and an engine rotation speed And the like.

Here, during steady operation of the engine, the ECU 10 uses the signals of the crankshaft rotation pulse and the camshaft rotation pulse from the crank angle sensor 27 as a reference for the fuel injection timing (valve opening timing) of the injectors 1-4. Also, by calculating the discharge amount of the high-pressure pump 7 (fuel pumping period), power is supplied to the injection pressure control solenoid valve 19 of the high-pressure pump 7 so that the common rail pressure is maintained at the optimum injection pressure (= target pressure). Control the timing.

Then, the fuel injection amount is calculated from the values measured by the rotation speed sensor 21, the accelerator opening sensor 22, the cooling water temperature sensor 25 or the fuel temperature sensor 24, and in order to achieve the calculated fuel injection amount, The engine is operated by driving the injection period control solenoid valves 11 to 14 of the injectors 1 to 4 with the injector energization time commands (values) calculated from the fuel pressure in the common rail 5 for each operation state.

When the vehicle occupant starts energizing the starter and cranks the crankshaft of the engine at or above the required minimum rotational speed for the purpose of starting the engine, the ECU 10 displays the characteristic diagram of FIG. As shown, the engine coolant temperature (TW) detected by the coolant temperature sensor 25,
Alternatively, an optimum injection start pressure for engine start (target rail pressure at start = target pressure) is calculated (injection start pressure determining means) in accordance with the compensation amount in which the starter ON duration is added to the engine cooling water temperature (TW), and the common rail is calculated. Until the pressure (actual rail pressure) rises above its target pressure, the injector energization time command (injector valve opening command) to each of the injectors 1 to 4 is prohibited.

From the characteristic diagram of FIG. 3, the lower the engine coolant temperature (TW), the higher the starting target rail pressure is set. In this embodiment, the engine coolant temperature (T
When W) is 5 ° C. or more, the starting target rail pressure is set to, for example, 30 MPa to 40 MPa. Further, when the engine cooling water temperature (TW) is 0 ° C. or lower and the engine cooling water temperature (TW) is lower than 0 ° C.
The target rail pressure at the time of starting is set to be higher (the inclination is larger) when the temperature is higher than or equal to ° C.

Next, the control method of the common rail type fuel injection system of the present embodiment will be described with reference to FIGS.
This will be briefly described based on the above. Here, FIG. 4 is a flowchart showing the start-time injection amount control by the ECU, and FIG. 5 is a diagram illustrating the starter ON signal, the rail fuel pressure, the engine rotation speed, the injector energization time command value, and the injection amount command value until the engine starts. 6 is a timing chart showing a change.

First, when the vehicle occupant turns the ignition switch from the OFF position to the ST position, the starter motor is rotated by the current from the battery, and at the same time, the pinion gear pushed by the overrunning clutch is directly connected to the engine crankshaft. The flywheel is rotated by meshing with the ring gear on the outer periphery of the wheel.

As a result, the crankshaft rotates,
As the piston moves up and down in the cylinder of the engine, air is drawn into the cylinder from the intake pipe. On the other hand, the high pressure pump 7
The fuel pressure in the common rail 5 is also increased by pressurizing the fuel pumped from the fuel tank 6 with the rotation of the engine crankshaft.

At this time, when the ignition switch is turned to the ST position, the ECU 10 turns on the starter which is generated by the contact between the movable contact and the fixed contact of the starter.
It is determined whether or not the signal is ON (starter energization start detecting means: step S1). If the result of this determination is NO, the start-time injection amount control ends.

As shown in the timing charts of FIGS. 5A to 5C, when the starter ON signal is OFF, that is, when the engine is stopped and the engine speed is 0 rpm, the common rail The fuel pressure in 5 (hereinafter referred to as the rail fuel pressure) is set to the atmospheric pressure. While the engine is stopped, the injection amount command value is also set to zero as shown in the timing chart of FIG.

If the result of the determination in step S1 is YES, that is, if the starter ON signal is ON, the engine is cranked at the minimum rotational speed (eg, 400 rpm) required for starting by the starter. Therefore, as shown in the timing charts of FIGS. 5B and 5C, the high-pressure pump 7
Is driven and the injection pressure control solenoid valve 19 is energized, whereby the fuel pressure in the common rail 5 (= rail rail fuel pressure) gradually increases.

Then, the fuel injection amount, the target injection pressure (target rail pressure), etc., which have been previously optimally adapted, are calculated (injection start pressure determining means: step S2). Specifically, a basic injection amount is calculated according to a digital value (cranking rotation speed, accelerator opening) obtained by A / D conversion of the sensor signals from the rotation speed sensor 21 and the accelerator opening sensor 22. The optimum injection amount at the start of the engine is calculated in consideration of a compensation amount such as a digital value (engine cooling water temperature) obtained by A / D conversion of a sensor signal from the cooling water temperature sensor 25 into the injection amount. Is stored in the RAM (see FIG. 5E).

Further, as shown in the characteristic diagram of FIG. 3, an optimum injection start pressure (= target pressure) for starting the engine is calculated based on the cooling water temperature of the engine, and the calculated injection start pressure is stored in the RAM. I do. Note that the injection start pressure (= target pressure) may be calculated by adding a compensation amount such as the starter ON duration to the calculated injection start pressure.

Next, a digital value obtained by A / D converting the sensor signal from the fuel pressure sensor 26 is detected, and it is determined whether or not the detected current common rail pressure (= actual rail pressure) is an optimum value. . That is, the cranking rotation speed is equal to the rotation speed required for starting the engine (for example, 400 rpm).
m) or more and whether or not the fuel pressure in the rail satisfies the injection start condition (there is no injection stop condition) equal to or higher than the target pressure (for example, 30 to 40 MPa) (injection inhibition determination means: step S3) . If this determination is NO,
That is, when fuel injection into the combustion chamber of the engine is prohibited, the routine returns.

Here, injection stop condition (injection prohibition condition)
Is determined when the cranking rotation speed is lower than the rotation speed required for starting the engine (for example, 400 rpm) or when the fuel pressure in the rail is equal to the target pressure (for example, 30 to 40 MPa).
a), when the ignition switch is returned to the OFF position, or when another injection stop request is issued.

If the decision result in the step S3 is YES, that is, the cranking rotational speed is equal to or higher than the rotational speed required for starting the engine (for example, 400 rpm), and the fuel pressure in the rail is set to the target pressure (for example, 30 to 40 MPa).
a) If the above-mentioned injection start condition is satisfied, an injection period is calculated from the fuel injection amount calculated in step S2 and the actual rail pressure detected by the fuel pressure sensor 26 (step S4). Thereafter, the start-time injection amount control ends.

According to the present embodiment, as shown in the timing charts of FIGS.
In particular, by setting the injection start pressure at the time of low-temperature start to an injection start pressure (= target pressure) that is optimal for starting the engine, the fuel injection is performed after the starter ON signal is turned on, that is, after the starter is energized. However, the cranking rotation speed is higher than the rotation speed necessary for starting the engine (for example, 400 rpm) and the fuel pressure in the actual rail is higher than the target pressure (for example, 30 to 40 MPa). By opening the injectors 1 to 4 at this time, fuel injection can be performed at an injection pressure optimal for starting the engine from the beginning of the injection start.

As a result, since the fuel injection does not have a bad effect such as lowering the temperature of the combustion chamber of the engine, the ignition of the fuel is facilitated by the heat of the air compression of the engine.
That is, since the starting of the engine becomes easy, the time until effective combustion is obtained can be shortened. Therefore, the injection period control solenoid valves 11 to 14 of the injectors 1 to 4
From the time when the injector energization time command values are output, that is, from when the injectors 1 to 4 are opened and fuel injection into the combustion chamber of each cylinder is started, until the first explosion is obtained in each cylinder. Time can be shortened. As a result, the common rail fuel injection device of the present embodiment is
As shown in the timing chart of FIG. 6C and FIG. 6C, the starting time from the start of energization to the starter (starter ON signal is turned on from OFF to ON) until the complete explosion is obtained is set to the conventional technology. This can be significantly reduced.

[Effects of the Embodiment] As described above, in the common rail type fuel injection device of the present embodiment, the fuel pressure in the common rail 5 is increased when the engine is started, especially when the engine is started at a low temperature in an extremely cold region of -10 ° C or less. Until the injection start pressure (optimum value) becomes optimal, the valve closing command to each of the injectors 1 to 4 is prohibited (the injector energization time command value is turned off).
By doing so, fuel injection from the injectors 1 to 4 into the combustion chamber of the engine is not performed.

Thus, the optimum injection pressure for starting the engine can be obtained in the first fuel injection after the engine is cranked by turning on the starter, and the time until the first explosion is induced is greatly reduced. Therefore, the startability of the engine, particularly, the low-temperature startability of the engine can be improved. Therefore, the engine of the present embodiment has a very good startability since the time until the complete explosion is short, and can be judged to be a diesel engine with a very good response since the time until the blow-up is short.

Here, after determining whether or not the starter ON signal is ON in the flowchart of FIG. 4, when calculating the optimum fuel injection amount and the optimum injection start pressure,
If the fuel injection amount and the injection start pressure (target rail pressure) are determined in consideration of the intake air temperature, the intake air pressure, the atmospheric pressure, the fuel temperature, the outside air temperature or the inside air temperature, etc., the control is further started by applying the control of the present invention. Time can be shortened.

[Modification] Here, the rotation speed of the engine at the time of starting the engine is a cranking rotation speed at which the engine is rotated by the starter. Then, this cranking rotation speed is detected by the rotation speed sensor 21,
The optimum injection start pressure (= target pressure) for starting the engine may be determined according to the detected cranking rotation speed.

This is because the lower the battery voltage is, the lower the rotation speed of the starter is, and thus the lower the cranking rotation speed is. The battery voltage decreases as the ambient temperature in the engine room, which depends on the temperature of the engine, decreases. Therefore, since the engine speed and the battery voltage are correlated with the engine temperature, even when the injection start pressure is determined by using the engine speed and the battery voltage, the startability at the time of low-temperature start is improved similarly to the engine coolant temperature. be able to.

In this embodiment, the fuel pressure sensor 26 is directly attached to the common rail 5 to detect the fuel pressure (common rail pressure, injection pressure) in the common rail 5.
The fuel pressure sensor 26 is connected to the discharge section of the high-pressure pump 7 and the fuel pipe 1.
8, the fuel pressure (common rail pressure, injection pressure) in the common rail 5 may be detected by attaching to any one of the high pressure pipe 8, the fuel passage in each of the injectors 1 to 4, the fuel reservoir, and the like.

In this embodiment, an example is described in which the variable discharge type high pressure pump 7 for varying the fuel discharge amount is used as the fuel pressure variable means for changing the fuel pressure in the common rail 5. As the fuel pressure variable means for changing the fuel pressure, a means for controlling the fuel pressure in the common rail 5 by reducing the fuel pressure in the common rail 5 from the common rail 5 by a pressure reducing valve or the like may be used.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a fuel piping system of a common rail type fuel injection device (Example).

FIG. 2 is a schematic configuration diagram showing a control system of the common rail type fuel injection device (Example).

FIG. 3 is a characteristic diagram showing a pressure value of a target rail pressure at the time of starting with respect to an engine cooling water temperature (Example).

FIG. 4 is a flowchart showing a start-time injection amount control by an ECU (embodiment);

FIG. 5 is a timing chart showing changes in a starter ON signal, a fuel pressure in a rail, an engine rotation speed, an injector energization time command value, and an injection amount command value until the engine is started (Example).

FIG. 6 is a timing chart showing changes in a starter ON signal, a rail fuel pressure, an engine rotation speed, an injector energization time command value, and an injection amount command value until the engine starts (prior art).

[Explanation of symbols]

Reference Signs List 1 injector (fuel injection valve) 2 injector (fuel injection valve) 3 injector (fuel injection valve) 4 injector (fuel injection valve) 5 common rail 7 high-pressure pump 10 ECU (fuel injection control means, injection start pressure determination means) 11 injection period Control electromagnetic valve (injection period variable means) 12 Injection period control electromagnetic valve (injection period variable means) 13 Injection period control electromagnetic valve (injection period variable means) 14 Injection period control electromagnetic valve (injection period variable means) 19 Injection pressure control solenoid valve (injection pressure variable means) 21 Rotation speed sensor (operating state detecting means) 22 Accelerator opening sensor (operating state detecting means) 23 Intake air temperature sensor 24 Fuel temperature sensor 25 Cooling water temperature sensor (engine temperature detecting means) ) 26 Fuel pressure sensor (fuel pressure detecting means) 27 Crank angle sensor (operating state detecting means)

Claims (4)

[Claims] 1. A common rail for accumulating high-pressure fuel discharged from a high-pressure pump, a plurality of fuel injection valves for injecting high-pressure fuel accumulated on the common rail into each cylinder of an engine, and accumulating in the common rail. A fuel pressure detecting means for detecting a fuel pressure of the high-pressure fuel, an operating state detecting means for detecting an operating state of the engine, a fuel pressure detected by the fuel pressure detecting means, and an engine pressure detected by the operating state detecting means. An accumulator-type fuel injection device comprising: a fuel pressure in the common rail and fuel injection control means for controlling a valve opening timing and a valve closing timing of the fuel injection valve based on an operation state, wherein the fuel injection control means Are engine temperature detecting means for detecting the temperature of the engine, and an engine in accordance with the engine temperature detected by the engine temperature detecting means. The fuel cell system further includes injection start pressure determining means for determining an optimum injection start pressure for starting, and the fuel pressure detected by the fuel pressure detecting means rises above the injection pressure optimum for engine start determined by the injection start pressure determining means. A pressure-accumulation type fuel injection device, wherein a valve opening command of the fuel injection valve is prohibited until the fuel injection valve is opened. 2. An accumulator type fuel injection device according to claim 1, wherein said engine temperature detecting means detects an intake air temperature of said intake air taken by said engine, and a fuel temperature sensor detects a temperature of fuel. An accumulator-type fuel injection device, which is at least one of a cooling water temperature sensor for detecting a cooling water temperature of the engine and an outside air temperature sensor for detecting a temperature of outdoor air. 3. A pressure accumulating fuel injection device according to claim 1, wherein said engine temperature detecting means detects a rotation speed of said engine when power supply to a starter for starting the engine is started. An accumulator-type fuel injection device, which is at least one of a battery voltage sensor that supplies electric power to the vehicle and an internal air temperature sensor that detects the temperature of indoor air. 4. An accumulator type fuel injection system according to claim 1, wherein the optimum injection pressure for starting the engine is set to a higher pressure value as the engine temperature is lower. An accumulator-type fuel injection device characterized by a target rail pressure at the time of starting.