JP2000310148A - Accumulator internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely ignite fuel, and start an engine early in an accumulator internal combustion engine. SOLUTION: In starting an engine, the ignition for fuel injected from an ignition valve 4 is facilitated to actuate an auxiliary starting means 24 for assisting starting the engine by a start controlling means 34 and 38, and control the actuation of pressure adjusting means 4a and 8a based on a pressure increasing degree set in accordance with a predictive time until making the fuel ignitable. The valve 4 is driven when the detecting pressure of a pressure detecting means 15 becomes a given value or more at the time of starting the engine by an injection controlling means 39, thereby injecting the fuel supplied from an accumulator 3 into respective cylinders.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure accumulating internal combustion engine for injecting high-pressure fuel stored in a pressure accumulating chamber into each cylinder from an injection valve.

[0002]

2. Description of the Related Art There has been known a pressure-accumulation type internal combustion engine in which high-pressure fuel stored in a pressure accumulator is injected into each cylinder from an injection valve in order to atomize injected fuel. For example, in a diesel engine, a common rail type diesel engine has been put to practical use in which high pressure fuel supplied from a high pressure pump is accumulated in a common rail which is an accumulation chamber, and an injector is operated to directly inject high pressure fuel into a combustion chamber. .

[0003] In this type of accumulator-type internal combustion engine, a fuel pump for pumping high-pressure fuel into an accumulator is driven by the internal combustion engine (engine). For example, in the case of a high-pressure pump (plunger pump) in a common rail fuel injection device, a camshaft that moves the plunger up and down is interlocked with the crankshaft of the engine, and the plunger moves up and down according to the rotation of the engine, and the fuel moves. , The compressed fuel is discharged to the common rail. Therefore, the fuel cannot be compressed when the engine is not rotating, and the fuel pressure in the common rail is reduced when the engine is started.
For this reason, when starting the engine, it is not possible to drive the injector to inject fuel immediately after the start of the starting operation, and the startability of the engine becomes a problem.

Therefore, in the technique disclosed in Japanese Patent Application Laid-Open No. H11-50881, the amount of pressure fed from the high-pressure pump to the common rail is maximized when the engine is started, and the rail pressure is quickly increased to improve the startability of the engine. At the same time, when the rail pressure exceeds the target pressure, it is possible to prevent a problem that the rail pressure exceeds the target pressure by extracting fuel in the common rail from a relief valve or the like.

[0005]

In a diesel engine, fuel is ignited by heat of compression when compressing intake air. However, the engine is sufficiently warmed up at the time of starting. Without it, the heat loss of the intake air is large and it is difficult to ignite the fuel reliably. Therefore, at the time of starting, the start-up assist device such as a glow plug or an intake heater raises the temperature in the cylinder or heats the intake air to promote the ignition of the fuel. For this reason, when the engine is started, even if the rail pressure is such that the injector can be driven, the engine cannot be started unless the fuel is ignited by the above-described start assist device.

In other words, in order to start the engine, the rail pressure must be equal to or higher than a predetermined pressure (at least the pressure at which the injector can be driven) to enable fuel injection, and the cylinder atmosphere such as the cylinder temperature must be controlled by the fuel. It is a condition that the engine can be ignited. Therefore, in order to start the engine early, it is a problem how to satisfy the above two conditions.

In this regard, in the above-mentioned prior art (Japanese Patent Laid-Open No. 11-50881), the starting auxiliary device preheats the combustion chamber before starting, and starts increasing the rail pressure after the elapse of the preheating period. Therefore, the time obtained by adding the rail pressure raising time to the preheating period is the time required for starting. For this reason, even if the rail pressure can be increased quickly, there is a limit in shortening the entire starting time.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide a pressure accumulating type internal combustion engine which enables reliable ignition of fuel and early start of the engine. I do.

[0009]

SUMMARY OF THE INVENTION In order to achieve the above object, a pressure accumulating internal combustion engine according to the present invention comprises:
The start-up control means activates the start-up assisting means to facilitate the ignition of the fuel injected from the injector and assists in starting the engine, and the degree of pressure increase set according to the predicted time until the fuel can be ignited. The operation of the pressure adjusting means is controlled on the basis of. Then, the injection control means drives the injection valve when the detected pressure of the pressure detection means becomes equal to or higher than a predetermined value at the time of starting the engine, and injects the fuel supplied from the accumulator into each cylinder.

[0010] Preferably, the degree of pressure increase in the accumulator is set based on a deviation between the target pressure at the time of starting the engine and the pressure detected by the pressure detecting means, and a predicted time until fuel can be ignited. Specifically, the pressure increase degree is set so that the time required for the pressure detected by the pressure detecting means to reach the target pressure at the time of starting the engine substantially coincides with the predicted time required for the fuel to become ignitable.

[0011] More preferably, a flow rate adjusting means capable of adjusting an amount of fuel pumped from the fuel pump is provided as the pressure adjusting means. Then, the amount of fuel fed under pressure is adjusted so as to change the degree of pressure increase in the accumulator according to the deviation between the detected pressure and the target pressure at the time of starting. Specifically, the greater the deviation, the greater the amount of fuel to be pumped and the greater the degree of pressure increase.

[0012] More preferably, a function of returning the fuel supplied from the accumulator to the fuel tank by idling as an adjusting means is added to the injection valve. Then, the injector is idled so as to reduce the pressure in the accumulator according to the deviation between the detected pressure and the target pressure at the time of starting, and the fuel supplied from the accumulator is returned to the fuel tank. Specifically, as the detected pressure is higher than the target pressure at the time of starting, the number of times of idling of the injection valve is increased to reduce the pressure in the accumulator.

[0013] More preferably, a fuel temperature detecting means for detecting or estimating the fuel temperature is provided, and the pressure is adjusted based on the detected fuel temperature. Specifically, the amount of the pumping fuel in the flow rate adjusting means is adjusted based on the fuel temperature, and
The number of idle shots at the injection valve is set based on the fuel temperature.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 show a pressure accumulating internal combustion engine as one embodiment of the present invention.
The case where the accumulator type internal combustion engine of the present invention is configured as a common rail type diesel engine is shown.

FIG. 1 shows a fuel injection system of the present common rail diesel engine. As shown in FIG. 1, the present fuel injection system 1 mainly includes a supply pump 2 as a fuel pump, a common rail 3 as an accumulator, an injector 4 as an injection valve, an ECU 5 for controlling these, and various sensors. ing. The supply pump 2 draws fuel from the fuel tank 6 and
This is a device that pressurizes and feeds the fuel to the common rail 3. The feed pump (low pressure pump) 7 sucks fuel from the fuel tank 6 and the high pressure pump 8 that pressurizes the fuel sucked by the feed pump 7 and feeds the fuel to the common rail 3. It is configured. As the feed pump 7, for example, a vane pump is used, and the rotation of a rotor having the vane continuously sucks and compresses fuel and discharges the fuel to the high-pressure pump 8. As the high-pressure pump 8, a plunger pump is used. The fuel is sucked into the plunger chamber by the reciprocating motion of the plunger, compressed, and fed to the common rail 3 through the check valve 8b.

The fuel pumping timing from the high-pressure pump 8 to the common rail 3 is synchronized with or before or after a later-described main injection timing of the injector 4 in order to suppress a decrease in rail pressure due to main injection and prevent deterioration of injection characteristics. It has become. In the present embodiment, the rotor of the feed pump 7 and the plunger of the high-pressure pump 8 are driven by a camshaft connected to a crankshaft of the engine.

The high-pressure pump 8 has a discharge amount control valve (P
CV (Pump Control Valve) 8a is provided.
The PCV 8a is an electromagnetic valve that controls the communication between the plunger chamber and the supply pipe 10 from the feed pump 7. By closing the PCV 8a when the plunger rises, the plunger chamber is closed and the fuel is pressurized.
By changing the opening / closing timing of a, the amount of compressed fuel in the plunger chamber, that is, the amount of discharge to the common rail 3 is adjusted. That is, PCV8a
Is a flow rate adjusting means for adjusting the amount of fuel fed from the high pressure pump 8 and functions as a pressure adjusting means for adjusting the rail pressure in the common rail 3. A filter 13 is provided on a supply pipe 12 connecting the fuel tank 6 and the supply pump 2. The fuel in the fuel tank 6 is drawn into the supply pump 2 after the impurities are removed by the filter 13.

The common rail 3 is a device for storing high-pressure fuel supplied from the supply pump 2, and is connected to the supply pump 2 by a high-pressure supply pipe 14. The common rail 3 is provided with a rail pressure sensor 15 as a pressure detecting means and a pressure limiter 16. The rail pressure sensor 15 is a pressure sensor that detects a rail pressure, and the detected rail pressure is output to the ECU 5. Also, the pressure limiter 16
Is a valve that opens when the rail pressure exceeds a predetermined value, opens when the rail pressure reaches a predetermined upper limit to release the pressure, and closes when the rail pressure decreases to the predetermined lower limit. Rail pressure is maintained. The fuel discharged from the pressure limiter 16 is returned to the fuel tank 6 through a return pipe (return passage) 17.

The injector 4 is a device for injecting fuel directly into each cylinder of the engine. The high-pressure fuel stored in the common rail 3 is supplied through a high-pressure supply pipe 18. FIG. 1 shows a case where the present fuel injection system 1 is applied to an in-line four-cylinder engine, and a total of four injectors 4 are provided. The common rail 3 and the injectors 4 are connected by independent high-pressure supply pipes 18, respectively.

Each injector 4 is provided with an injector control valve 4a. The injector control valve 4a
This is an electromagnetic valve for controlling the opening and closing of the nozzle 4b, which is an injection port. When no power is supplied to the injector control valve 4a, the nozzle 4b is opened and injection is not performed. On the other hand, when power is supplied to the injector control valve 4a, the nozzle 4b is opened and injection is started, and injection is performed while power is supplied. Therefore, the start / end of fuel injection from the injector 4 can be controlled by the start / end of energization to the injector control valve 4a, and the ECU 5 controls the timing of energization to the injector control valve 4a to control the fuel injection amount and the fuel injection amount. The fuel injection timing is controlled.

Further, in the injector 4 according to the present fuel injection system 1, the valve body for opening the nozzle 4b is indirectly driven by an electromagnetic force, and power is supplied to the injector control valve 4a. It takes a very short time for the nozzle 4b to open, during which time fuel flows out of the injector control valve 4a to the return pipe 19.

Therefore, by controlling the time of energization to the injector control valve 4a, the fuel in the common rail 3 is discharged without injecting fuel from the nozzle 4b.
That is, the injector 4 can be idled to reduce the rail pressure. That is, the injector control valve 4a functions as pressure adjusting means for reducing and adjusting the rail pressure. The return pipe 1
Reference numeral 9 denotes a pipe for returning fuel from the injector 4 to the fuel tank 6, and includes a pressure limiter 16 and a fuel tank 6.
Is connected to a return pipe 17 connecting the Further, a fuel temperature sensor 20 as fuel temperature detecting means is provided on the return pipe 17 downstream of a connection portion between each injector 4 and the return pipe 19, and outputs the detected fuel temperature to the ECU 5. It has become.

Further, a glow plug 24 as a starting assisting means is disposed in a combustion chamber (not shown) of the engine. The glow plug 24 glows itself by flowing current through the internal heating wire when the engine is started,
This raises the temperature of the air inside the combustion chamber,
It serves as an ignition heat source for the injected fuel to promote the ignition of the fuel. A water temperature sensor 22 is provided on a water jacket (not shown) of the engine, and outputs a detected water temperature to the ECU 5.

Next, an ECU for controlling each of the above devices
The ECU 5 includes a rail pressure A / D converter 30 and a fuel temperature A / D converter 3 as its functional elements.
1, water temperature detection means 32, operation mode setting means 33, glow plug control means 34, rail pressure control means (pressure control means) 35, injector control means (injection control means) 36
Is provided.

First, the rail pressure A / D conversion means 30 is means for sampling the rail pressure data input from the rail pressure sensor 15 and performing A / D conversion. Timing (for example, 90 to 105 ° BTDC for an in-line four-cylinder engine)
To read the data and A / D convert the data. The rail pressure A / D conversion means 30 and the rail pressure sensor 15 constitute a rail pressure detection means. The fuel temperature A / D conversion means 31 is means for sampling the fuel temperature data input from the fuel temperature sensor 20 at a predetermined cycle and performing A / D conversion, and the water temperature A / D conversion means 32 is a water temperature A / D conversion means 32. This is a means for sampling the water temperature data input from the CPU at a predetermined cycle and performing A / D conversion.

The operation mode selection means 33 is a means for selecting an operation mode according to the state of the engine. In this case, the operation mode selection means 33 selects one of a start mode and a normal mode. The start mode is an operation mode from when the start switch is turned on to when the engine becomes operable. When the engine becomes operable, the normal mode is selected. In switching from the start mode to the normal mode, preheating of the glow plug 24 (glow preheating) is completed, the rail pressure reaches the target rail pressure at the time of starting, cylinder identification is completed, and the engine speed increases to a predetermined value. It is a condition. The cylinder identification is performed by calculating the top dead center (TDC) of each cylinder from the crank angle detected by the crank angle sensor 21.

The glow plug control means 34 is a means for operating the glow plug 24 when the engine is started. The glow plug control means 34 turns on the start switch 25 and starts energizing the glow plug 24. The energization time is referred to from a map using the water temperature as a parameter, and is set such that the lower the water temperature, the longer the energization time.

Next, the rail pressure control means 35 will be described. The rail pressure control means 35 is means for controlling the rail pressure in the common rail 3 and aims at realizing the rail pressure according to the operating state of the engine. Therefore, the rail pressure control means 35 includes the target rail pressure setting means 37 and the starting rail pressure control means 3 as its functional elements.
8. A normal rail pressure control means 39 is provided.

First, the target rail pressure setting means 37 sets a target rail pressure for performing optimum fuel injection according to the operating state of the engine (engine speed, accelerator opening, water temperature, etc.). This is a means for setting as a rail pressure. The target rail pressure is stored in a map that uses the operating state of the engine as a parameter in accordance with the operation mode. For example, the target rail pressure in the start mode is stored as a map for the water temperature data detected by the water temperature sensor 22. Note that the target rail pressure at the time of starting is higher than the rail pressure at which the injector 4 can operate, and is a rail pressure (for example, 35 to 40 MPa) at which the injected fuel is sufficiently atomized to reliably ignite.

The starting rail pressure control means 38 functions in the starting mode, and controls the PCV 8a and the injector control valve 4a so that the starting rail pressure becomes the starting target rail pressure. Together with the control means 34, it constitutes start-up control means. Describing a specific method of control, the rail pressure is lower than the target rail pressure at the time of starting, and it is necessary to increase the rail pressure to the target rail pressure at the time of starting. Therefore, the starting rail pressure control means 38 opens the PCV 8 a so that the rail pressure becomes the starting target rail pressure, and feeds the fuel to the common rail 3.

At this time, the starting rail pressure control means 38 first calculates a deviation between the starting target rail pressure and the current rail pressure. This deviation corresponds to the amount of fuel to be pumped to the common rail 3. Next, the timing at which glow preheating by the glow plug 24 is completed (the number of rotations since the start of cranking) is referred to from a map using the water temperature as a parameter. This is because there is a high possibility that the fuel will not ignite well even when fuel is injected in the cold state, and glow preheating is performed by the glow plug 24 until ignition is reliably performed. This is because it is only necessary to complete the process before the process is completed. In addition,
The glow preheating completion timing (hereinafter referred to as glow preheating completion timing) is set to be slower as the water temperature is lower.
4 is set to a time shorter than the energization time.

When the deviation between the target starting rail pressure at the start and the rail pressure at the present time and the glow preheating completion timing are calculated, the starting rail pressure control means 38 obtains the fuel amount from a map using these as parameters. The pumping ratio is determined. In other words, for example, when the glow preheating completion timing is the third rotation as shown in FIG. 2, the number of times of pressure feeding from the high-pressure pump 8 is also three times, so that the deviation between the starting target rail pressure and the current rail pressure is obtained. The fuel amount calculated from the above is divided into three and pressure-fed, and the rail pressure becomes the target rail pressure at the start in the third pressure-fed.

In this map, the characteristic is set such that the larger the deviation, the larger the amount of fuel to be pumped and the degree of pressure increase, and the amount of fuel to be pumped is reduced as soon as a large amount of fuel is pumped in the first pumping. It is going to go. For example, in the case shown in FIG. 3, the first pumping amount is the largest, and the second and third pumping amounts are gradually reduced. When the glow preheating period is short and the rail pressure increase is not completed by the glow preheating completion timing, the pumping amount is maximized and the pressure is immediately increased to the starting target rail pressure.

When the pumping ratio of the fuel is determined, the PCV 8a is controlled according to the determined pumping ratio. That is, the opening and closing timing of the PCV 8a is changed by adjusting the energization timing and time according to the pressure feeding ratio, and the discharge amount from the high-pressure pump 8 to the common rail 3 is adjusted. Since the volume of fuel changes with temperature,
Even at the same pumping amount, the degree of increase in the rail pressure varies depending on the fuel temperature. Therefore, the starting rail pressure control means 38
In the first embodiment, the PCV 8a is controlled after correcting the pumping amount according to the fuel temperature detected by the fuel temperature sensor 20.

When the pumping from the high-pressure pump 8 is completed, the deviation between the starting target rail pressure and the rail pressure at the completion of the pumping is calculated. If the rail pressure does not reach the starting rail pressure, the PCV 8a is re-started. Is driven to perform pressure feeding. On the other hand, when the rail pressure is higher than the starting target rail pressure, the injector control valve 4a is driven to perform idling, the fuel in the common rail 3 is consumed, and the rail pressure is reduced.
The number of idle shots of the injector 4 is determined from a map using the target rail pressure at start and the deviation between the target rail pressure at start and the rail pressure as a parameter. After correcting according to the fuel temperature, the injector control valve 4a is driven.

When the deviation between the rail pressure and the starting target rail pressure becomes smaller than a predetermined value and cylinder identification is completed by the above control, fuel injection from the injector 4 is started. With the start of the fuel injection, the starting-time rail pressure control means 38 switches from the rail pressure control based on the above map to the rail pressure control by feedback control. In other words, the deviation between the starting target rail pressure and the rail pressure is calculated for each stroke, and the timing and time for energizing the PCV 8a are adjusted according to the deviation. The feedback control by the starting rail pressure control means 38 is performed until the engine rotation speed reaches a predetermined value.

The normal rail pressure control means 39 functions in the normal mode, and controls the PCV 8a while feeding back the deviation of the detected rail pressure from the target rail pressure. Specifically, the energization timing and time corresponding to the opening / closing timing of the PCV 8a determined from the target rail pressure according to the operating state of the engine (engine speed, accelerator opening, etc.) and a target injection amount described later are set as basic control amounts. While controlling, the basic control amount is corrected by a control amount corresponding to the deviation of the detected rail pressure from the target rail pressure.

Next, the injector control means 36 will be described. The injector control means 36 controls the fuel injection start timing and the fuel injection timing by controlling the power supply start timing and power supply time (pulse width) of the injector 4 to the injector control valve 4a. This is a means for controlling the injection amount, and comprises a target injection amount setting means 40 and an injection control means 41. The target injection amount setting means 40 is a means for setting a target injection amount from the injector 4, and is configured to set the target injection amount according to the operating state of the engine (engine speed, accelerator opening, etc.). .

The injection control means 41 is means for driving the injector 4 and determines the injection start timing and injection time and outputs a drive pulse to the injector control valve 4a. In the normal mode, the injection start timing is determined according to the operating state of the engine (engine speed, accelerator opening, etc.). On the other hand, in the start mode, the injection start condition is when the deviation between the rail pressure and the target rail pressure at start is smaller than a predetermined value and the cylinder identification is completed. Further, the injection time is determined based on the target injection amount set by the target injection amount setting means 40 and the rail pressure. The start timing of energization is measured using a pulse output from the crank angle sensor 21.

Since the pressure accumulating internal combustion engine according to one embodiment of the present invention is configured as described above, at the time of starting, fuel injection control is performed according to, for example, the flow charts shown in FIGS. Hereinafter, the fuel injection control according to the accumulator-type internal combustion engine will be described with reference to flowcharts shown in FIGS. As shown in FIG.
First, it is determined whether or not the start switch 25 is on (step S100), and the engine speed N
e is smaller than a predetermined value Ne1 (step S
110) is performed. When the start switch 25 is on and the engine speed Ne is lower than the predetermined value Ne1, the start mode is selected by the operation mode selection means 33, and the water temperature A / D conversion means 32 and the fuel temperature A / D conversion means 31 are selected. , Rail pressure conversion means 30 samples the water temperature, oil temperature, and rail pressure Pcr, respectively (step S12).
0).

Next, the rail pressure control means 34 sets the starting target rail pressure Pcsttg according to the water temperature sampled from the map using the water temperature as a parameter (step S130). Then, a deviation ΔPc between the actual rail pressure Pcr and the starting target rail pressure Pcsttg (ΔPc = Pcr−Pcsttg)
) Is calculated (step S140), and it is determined whether or not this deviation ΔPc is within the dead zone (P2 <ΔPc <P3) (step S150). Note that P2 is a negative predetermined value, and P3 is a positive predetermined value. If the deviation ΔPc is not within the dead zone, it is determined whether the deviation ΔPc is equal to or less than a predetermined value P2.
(Step S160).

When the deviation ΔPc is equal to or less than the predetermined value P2,
Glow preheating completion timing Nst by glow plug 24
Is predicted from a map using the water temperature as a parameter (step S170). Then, the fuel pumping ratio for each stroke is set from a map using the predicted glow preheating completion timing Nst and the deviation ΔPc as parameters (step S18).
0). When the fuel pumping ratio is set for each stroke, the set pumping ratio is further corrected according to the fuel temperature (
Step S190), PCV based on the corrected pumping ratio
The energization time and timing of 8a are adjusted to pump the fuel from the high-pressure pump 8 to the common rail 3 (step S200).
In this way, by determining the fuel pumping ratio for each stroke and performing pumping, the rail pressure gradually increases to the starting target rail pressure Pcsttg.

When the pumping of the fuel is completed, step S is performed again.
100, the water temperature, the oil temperature,
The rail pressure Pcr is sampled, and a deviation ΔPc (ΔPc = Pcr−P) between the sampled rail pressure Pcr and the starting target rail pressure Pcsttg set in step S130.
csttg) is calculated (step S140). At this time,
When the deviation ΔPc is equal to or smaller than the predetermined value P2 (step S1
50, S160), and the pumping from the high-pressure pump 8 is performed again by the processing after step S170. On the other hand, the deviation ΔP
When c is equal to or larger than the predetermined value P3 (steps S150, S
160), in step 210, the number of idle shots of the injector 4 is set from a map using the starting target rail pressure Pcsttg and the deviation ΔPc as parameters. Then, the set number of times of idling is corrected according to the fuel temperature (step S220), and the injector control valve 4a is driven based on the corrected number of times of idling (step S220). By idling the injector 4 in this manner, the fuel in the common rail 3 is extracted, and the rail pressure gradually decreases to the target rail pressure Pcsttg at the time of starting.

Thus, the deviation ΔPc between the actual rail pressure Pcr and the starting rail pressure Pcsttg is within the dead zone (P2 <ΔPc
<P3) (step S150), the ECU 5 then proceeds to step S300 in FIG. 4 to determine whether or not the cylinder identification has been completed. Then, when the cylinder identification is completed, the starting fuel injection permission flag is turned on (step S310). The injector control means 35 starts fuel injection by turning on this flag (step S32).
0).

When fuel injection is started, the rail pressure control means 34 starts feedback control of the rail pressure in the starting mode (step S330). The feedback control in this start mode is performed until the engine rotation speed Ne exceeds the predetermined value Ne4 through the determination in step S340. After the engine speed Ne exceeds the predetermined value Ne4, the operation mode shifts from the start mode to the normal mode, Rail pressure control and fuel injection control are performed.

As described above, according to the present pressure-accumulation type internal combustion engine, the rail pressure in the common rail 3 is increased to the target rail pressure at the time of starting simultaneously with the preheating period by the glow plug 24. Immediately after the completion of the preheating by the fuel injection from the injector 4 becomes possible,
There is an advantage that the engine can be started early while enabling reliable ignition of the fuel.

Further, according to the pressure accumulating type internal combustion engine, it is possible to start the fuel injection at an appropriate rail pressure at the time of starting the engine. There is an advantage that the engine can be started at an early stage without performing, and vibration and noise can be suppressed to prevent a decrease in the life of the engine.

In the fuel pumping from the high-pressure pump 8 at the time of starting, the larger the deviation between the target rail pressure at starting and the detected rail pressure, the greater the amount of fuel to be pumped. Large amount of fuel can be pumped at the beginning of the pumping, and the pumping amount can be reduced at the end of the pumping. Thus, there is an advantage that pulsation of the rail pressure accompanying the fuel pumping can be suppressed, and fuel injection can be started at a more appropriate rail pressure. Furthermore, the high pressure pump 8
Is adjusted in accordance with the fuel temperature detected by the fuel temperature sensor 20 in consideration of a volume change according to the fuel temperature, so that the fuel injection can be performed with a more appropriate rail pressure. There is the advantage that it is possible to get started.

It should be noted that the present invention is not limited to the above-described embodiment, and can be implemented with various modifications without departing from the spirit of the present invention. For example, in the above-described embodiment, the case in which the glow plug 24 is employed as the start-up assisting means has been described. However, the intake air is heated by installing an intake heater in the intake pipe, and the heated air is sent into the cylinder. The ignition may be facilitated.

In the above-described embodiment, the injector 4 is driven based on the difference between the target pressure at the time of starting and the detected pressure, but the detected pressure is equal to or more than a predetermined value determined according to the engine state at the time of starting. It may be made to drive when it becomes. Further, in the above-described embodiment, the rail pressure is reduced by idling of the injector 4. However, the common rail 3 is provided with a pressure regulating valve which can be controlled by the ECU 5, and the common rail 3 is opened by opening the pressure regulating valve. The pressure may be reduced by discharging the fuel.

In the above-described embodiment, the case where the PCV type pump is used as the high pressure pump 8 has been described. However, the IMV type pump may be used. In this case, the discharge amount to the common rail 3 can be adjusted by controlling the drive duty. Further, in the above-described embodiment, a case has been described in which an injector of a type in which high-pressure fuel is directly supplied to the nozzle portion and injected is employed as the injector 4, but other types of injectors, for example, separately from high-pressure oil stored in a common rail, are used. An injector of a type in which low-pressure fuel is guided to the nozzle portion, and the low-pressure fuel in the nozzle portion is pressurized and injected by the hydraulic pressure of high-pressure oil through a stepped piston may be used.

Further, in the above-described embodiment, the case where the present invention is configured as a common rail type diesel engine has been described. However, the application example of the present invention is not limited to this, and the high pressure fuel stored in the accumulator is supplied from the injection valve. The present invention can of course be applied to any type of fuel injection device for an internal combustion engine that injects fuel into each cylinder.

[0053]

As described in detail above, according to the accumulator type internal combustion engine of the present invention, it is possible to inject fuel from the injector immediately after the fuel can be ignited, and it is possible to reliably supply the fuel. There is an advantage that the engine can be started early while enabling ignition.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a fuel injection system according to a pressure accumulating internal combustion engine as one embodiment of the present invention.

FIG. 2 is an explanatory diagram for describing a rail pressure control method at the time of starting the pressure accumulating type internal combustion engine as one embodiment of the present invention.

FIG. 3 is a flowchart showing a flow of fuel injection control according to the pressure accumulating internal combustion engine as one embodiment of the present invention.

FIG. 4 is a flowchart showing a flow of fuel injection control according to the pressure accumulating internal combustion engine as one embodiment of the present invention.

[Explanation of symbols]

2 Supply pump (fuel pump) 3 Common rail (accumulation chamber) 4 Injector (injection valve) 4a Injector control valve (pressure adjusting means) 5 ECU 6 Fuel tank 8 High pressure pump 8a PCV (pressure adjusting means) 15 Pressure detecting means Rail pressure sensor 24 Glow plug (start assisting means) 30 Rail pressure A / D converting means 30 constituting pressure detecting means 30 34 Glow plug controlling means constituting starting control means 36 Injector controlling means (injection controlling means) 38 Start controlling means Starting rail pressure control means constituting

Continued on the front page F term (reference) 3G066 AA07 AC09 AD02 BA00 BA22 CB12 CB15 CC05U CD26 CE22 CE29 DA01 DA04 DA06 DA09 DB01 DC04 DC05 DC09 DC14 DC15 DC18 3G301 HA02 HA06 JA06 JA37 KA01 LA00 LB11 LB17 LC10 MA11 MA18 MA23 NA03 NB02 NB02 NE23 NE25 PB01Z PB08A PB08Z PE01Z PE03Z PE04Z PE05Z PE08Z PF03Z PF16Z

Claims (1)

[Claims] An accumulator for storing fuel pumped by a fuel pump in a pressurized state, pressure detecting means for detecting or estimating the pressure in the accumulator, pressure adjusting means for adjusting the pressure in the accumulator, An injection valve provided for each cylinder of the internal combustion engine for injecting fuel supplied from the pressure accumulating chamber into the cylinder, and starting to assist ignition of the engine by facilitating ignition of the fuel injected from the injection valve An auxiliary means, when starting the engine, activating the start auxiliary means, and setting a degree of pressure increase in the accumulator according to a predicted time until fuel can be ignited by the start auxiliary means; Start control means for controlling the operation of the pressure adjusting means based on the degree; and injection control means for driving the injection valve when the pressure detected by the pressure detection means becomes greater than or equal to a predetermined value when the engine is started. That A pressure accumulating internal combustion engine, characterized by: