JP2001152922A - Common rail type fuel injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To high-efficiently prevent incurring of an energy loss due to the wasteful work of a high pressure pump in a common rail type fuel injection device. SOLUTION: Fuel in a common rail 8 is pressurized by a forced feed of fuel to a common rail 3 by a high pressure pump 8 driven by an internal combustion engine and the pressurized fuel is supplied to an injection valve 4 through the common rail 8 and injected in each of the cylinders of the internal combustion engine. In so formed constitution, a control valve 23 is provided to control an amount of fuel supplied to the common rail 3 from the high pressure pump 8 and operation of the control valve 23 is controlled by a control means 37 such that a pressure in the common rail 8 detected by a pressure detecting means 15 is maintained at a given target pressure. In this case, a control amount on the control valve 23 is corrected based on pump efficiency and/or a fuel temperature changed according to the rotation speed of the internal combustion engine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In recent years, in order to atomize injected fuel, a common rail type fuel injection device in which high pressure fuel stored in a common rail is injected from an injection valve into each cylinder has been put into practical use. Equipped with an engine. In the common rail fuel injection system, the fuel in the common rail is pressurized by pumping the fuel to the common rail by the high pressure pump.However, if the amount of pumping from the high pressure pump is small, the optimum Rail pressure (pressure in the common rail) cannot be realized. For this reason, conventionally,
Maintains the optimum rail pressure by sending the fuel amount exceeding the amount injected from the injection valve from the high pressure pump to the common rail, feeding back the rail pressure detected by the pressure gauge and discharging excess fuel from the pressure reducing valve. I was trying to do it.

However, in this case, the high-pressure pump wastes the excess fuel discharged, and wastes the energy of the wasteful work of the high-pressure pump, thereby deteriorating the fuel efficiency. In this regard, Tokuhei 7-12
No. 2422 discloses that only a necessary amount corresponding to the fuel consumption amount due to the injection is fed from the high pressure pump to the common rail in synchronization with the rail pressure drop, thereby reducing the wasteful work of the high pressure pump while maintaining the optimum rail pressure. A technique for preventing such a situation is disclosed.

[0004]

By the way, the pump efficiency of the high-pressure pump depends on the pump rotation speed. However, since the high-pressure pump is usually driven by the engine, if the engine rotation speed changes, the pump rotation speed also increases. Change.
Therefore, the pump efficiency changes according to the engine speed, and the amount of fuel discharged from the high-pressure pump also changes. For this reason, if the influence of the engine rotation speed on the pump efficiency is ignored in determining the amount of pumping to the common rail, an error may occur in the actual amount of pumping.

Similarly, the amount of fuel discharged from the high-pressure pump varies depending on the temperature of the fuel, but the fuel temperature always varies depending on the temperature or the like. Therefore, the influence of the fuel temperature cannot be neglected in determining the amount of pumping to the common rail. This point is not considered at all in the prior art (Japanese Patent Publication No. Hei 7-122422). That is, in the above prior art, the amount of fuel pumped from the high-pressure pump to the common rail is changed according to the injection amount or the engine rotation speed so that the predetermined rail pressure can be accurately maintained, but this is consumed by the injection. Focusing only on the amount of fuel, the fact that the amount of fuel discharged from the high-pressure pump changes in accordance with the pump efficiency and the fuel temperature is ignored in determining the amount of pumping to the common rail.

For this reason, the control according to the conventional technique described above naturally has a limit in accurately supplying a necessary amount of fuel to the common rail, and it cannot be said that the wasteful work of the high-pressure pump can be sufficiently prevented. The present invention has been made in view of such a problem, and an object of the present invention is to provide a common rail type fuel injection device capable of more efficiently preventing energy loss due to useless work of a high-pressure pump.

[0007]

According to a first aspect of the present invention, there is provided a common rail fuel injection system comprising: a high pressure pump driven by an internal combustion engine for pumping fuel to a common rail; In the configuration in which the fuel is pressurized, the pressurized fuel is supplied from the common rail to the injection valve and injected into each cylinder of the internal combustion engine, the control valve for controlling the amount of fuel supplied from the high-pressure pump to the common rail is provided. As the pressure in the common rail detected by the pressure detecting means is maintained at a predetermined target pressure,
The operation of the control valve is controlled by the control means. At this time, the control amount for the control valve is corrected based on the pump efficiency and / or the fuel temperature that change according to the rotation speed of the internal combustion engine.

According to a second aspect of the present invention, there is provided a common rail type fuel injection system according to the first aspect, further comprising a low pressure pump for supplying fuel to a high pressure pump, and the control valve for controlling the pressure from the low pressure pump to a high pressure. Controls the amount of fuel supplied to the pump. When the low-pressure pump is driven by the internal combustion engine, it is preferable to correct the control amount for the control valve based on the discharge pressure of the low-pressure pump that changes according to the rotation speed of the internal combustion engine.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a configuration of a common rail fuel injection device as one embodiment of the present invention. As shown in FIG. 1, the present fuel injection device 1 mainly includes a supply pump 2 as a fuel pump, a common rail 3 as a pressure accumulation chamber, an injector 4 as an injection valve, an ECU 5 for controlling these, and various sensors. Have been.

The supply pump 2 is a device for sucking up fuel from the fuel tank 6, pressurizing the fuel and sending it to the common rail 3. The low-pressure pump 7 sucks fuel from the fuel tank 6, and the fuel pumped by the low-pressure pump 7. And a high-pressure pump 8 that pressurizes and feeds the common rail 3. A vane pump is used as the low pressure pump 7,
The rotation of the rotor having the vane continuously sucks and compresses the fuel and discharges the fuel to the high-pressure pump 8.
The rotor of the low-pressure pump 7 is connected to the crankshaft of the engine and is driven to rotate.

A variable throttle valve (control valve) 23 is provided on a supply pipe 10 connecting the low pressure pump 7 and the high pressure pump 8. The variable throttle valve 23 is a solenoid valve that adjusts the amount of oil sent from the low-pressure pump 7 to the high-pressure pump 8.
By changing the drive duty, the amount of oil sent to the high-pressure pump 8 is adjusted, and the amount of oil sent from the high-pressure pump 8 to the common rail 3 is adjusted. The control of the variable throttle valve 23 is performed by an ECU 5 described later.

As the high-pressure pump 8, a plunger pump is used. In particular, in the present embodiment, the high-pressure pump 8
Throttle valve 23 adjusts the amount of pressure feed from
Therefore, a free piston type plunger pump is employed. More specifically, as shown in FIG. 2A, the high-pressure pump 8 according to the present embodiment includes a plunger 8a, a plunger barrel 8b, and a cam 8d. The plunger 8a and the plunger barrel 8b are fitted in a liquid-tight manner, and a pump chamber 8c is formed between the head of the plunger 8a and the plunger barrel 8b. The cam 8d is a plunger barrel 8b of the plunger 8a.
, And is connected to the crankshaft of the engine and driven to rotate.

The pump chamber 8d communicates with the variable throttle valve 23, and the fuel discharged from the low-pressure pump 7 and the flow rate of which is adjusted in the variable throttle valve 23 is supplied into the pump chamber 8c and the plunger 8a is supplied by the supplied fuel amount. Only to push it down. Then, as shown in FIG. 2B, when the plunger 8a pushed down by the fuel supply from the variable throttle valve 23 comes into contact with the rotating cam 8d, the plunger 8a
Is pushed up again by the cam 8d, compresses the fuel in the pump chamber 8d and feeds it to the common rail 3 through the check valve 8e.

At this time, the timing of pumping the fuel from the high-pressure pump 8 to the common rail 3 is synchronized or synchronized with the later-described main injection timing of the injector 4 in order to suppress a decrease in rail pressure due to main injection and to prevent deterioration of injection characteristics. It is set to be before and after, that is, near TDC (top dead center). 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 reducing valve 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. The pressure reducing valve 16 is a valve that opens when the rail pressure exceeds a predetermined value. When the rail pressure reaches a predetermined upper limit, the valve is opened to release the pressure, and the rail pressure decreases to a predetermined lower limit. By the way, the valve is closed to maintain the rail pressure. Note that the fuel extracted from the pressure reducing valve 16 is returned to the fuel tank 6 through the return pipe 17.

The injector 4 is a device for directly injecting fuel 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 device 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 the injector control valve 4a is energized, the nozzle 4b is opened and the injection is started, and the injection is performed during the energization. Therefore, the start / end of the fuel injection from the injector 4 can be controlled by the energized state of the injector control valve 4a, and the ECU 5 controls the injector control valve 4a.
The amount of fuel injection and the timing of fuel injection are controlled by controlling the timing of energization of a.

The injector 4 according to the present fuel injection device is connected to the injector control valve 4a until power is supplied to the injector control valve 4a and the nozzle 4b is opened.
The structure is such that fuel flows out from the fuel tank to the return pipe 19. Therefore, by controlling the energization time to the injector control valve 4a, the fuel in the common rail 3 is consumed without injecting the fuel from the nozzle 4b, that is, the injector 4 is idled to reduce the rail pressure. It has become possible. The return pipe 19
Is a pipe for returning fuel from the injector 4 to the fuel tank 6 and is connected to a return pipe 17 connecting the pressure reducing valve 16 and the fuel tank 6.

Further, a fuel temperature sensor 20 is provided on the return pipe 17 at a position downstream of the connection with the return pipe 19 from each injector 4. Fuel temperature sensor 20
Is a sensor for detecting the fuel temperature, and the detected fuel temperature is output to the ECU 5. Next, the ECU 5 that controls the above devices will be described.
The ECU 5 is an electronic control unit including a CPU, a RAM, a ROM, an I / O interface, and the like.
A fuel temperature measuring means 32, a rail pressure control means 33, and an injector control means 34 are provided.

First, the rotation speed measuring means 30 will be described.
This is a means for measuring e, and calculates the rotation speed Ne based on a pulse input from a crank angle sensor 21 provided on a crankshaft (not shown). Specifically, as shown in FIG. 3, the crank angle sensor 21 outputs a pulse every 6 ° CA in conjunction with the rotation of the crankshaft, and does not output a pulse for only three pieces near 90 ° BTDC. It has become. That is, the crank angle sensor 21 detects two strokes in one stroke (half rotation of the crankshaft).
It outputs seven pulses. In the rotation speed measuring means 30, the last (27th) before 90 ° BTDC
The time from the pulse input to the first (first) pulse input after 90 ° BTDC is measured by a timer, and the rotation speed Ne is calculated from the time and the angle.

The rail pressure measuring means 31 is a rail pressure sensor 1
This is means for reading rail pressure data detected in step 5 and performing A / D conversion. Here, at the time of inputting the 27th pulse shown in FIG. 3, data is read and A / D converted, and is used as the detected rail pressure Pcr in the following control. The fuel temperature measuring means 32 is means for reading the fuel temperature data detected by the fuel temperature sensor 20 at a predetermined cycle and performing A / D conversion.

Next, the rail pressure control means 33 will be described. The rail pressure control means 33 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. For this reason, the rail pressure control means 33 is provided with target rail pressure setting means 35, pressure-feed / discharge determination means 36, pressure-feed control means 37, and discharge control means 38 as its functional elements.

The target rail pressure setting means 35 is a means for setting, as the target rail pressure Pct, a rail pressure for performing optimum fuel injection according to the operating state of the engine. Here, it is assumed that the operating state of the engine is determined from the engine rotation speed and the fuel injection amount, and the engine rotation speed Ne and the final fuel injection amount Qfin at the previous stroke edge (at the 27th pulse input point) shown in FIG. Based on this, the target rail pressure Pct for injection in the next stroke is determined. As the final fuel injection amount Qfin, the total fuel injection amount in the previous stroke (that is, the sum of the fuel injection amounts in each injection such as expansion stroke injection, pilot injection, main injection, and post injection) is used. I have.

The feed / discharge determining means 36 sends the fuel to the common rail 3 to discharge the fuel from the common rail 3 in order to achieve the target rail pressure Pct set by the target rail pressure setting means 35, or also sends the fuel. This is a means for determining whether or not to discharge. The pumping / discharging determination means 36 determines the above determination based on the target rail pressure Pct and the estimated rail pressure P after injection.
This is performed based on the deviation Pctes from es (Pctes = Pct−Pes). That is, it is assumed that the final fuel injection amount in the relevant stroke is close to the final fuel injection amount Qfin in the previous stroke, and the rail after the fuel injection in the relevant stroke is determined from the detected rail pressure Pcr and the final fuel injection amount Qfin in the previous stroke. Pressure Pe
s is estimated, and if the deviation Pctes from the target rail pressure Pct is positive, pumping is performed to increase the rail pressure, and conversely, if the deviation Pctes is negative, discharging is performed to reduce the rail pressure. When the deviation Pctes is zero, it is determined that the current state is maintained. Then, the pressure feed control means 37 or the discharge control means 38 functions based on the determination by the pressure feed / discharge determination means 36.

The pressure feed control means 37 includes a pressure feed discharge determination means 3
6, which is a means for controlling the variable throttle valve 23 based on the pumping determination, and adjusts the amount of fuel pumped from the high-pressure pump 8 to the common rail 3 so that the rail pressure after fuel injection becomes the target rail pressure Pct. To explain specific control contents, as shown in FIG. 4, first, a basic drive duty of the variable throttle valve 23 is determined from a map M1 using the detected rail pressure Pcr and the deviation Pctes (Pctes = Pct−Pes) as parameters. It is supposed to. Then, the following correction is performed on the determined basic drive duty.

First, the first correction is a correction corresponding to the discharge pressure of the low-pressure pump 7. When the low-pressure pump 7 is driven independently like an electric pump, the discharge pressure can be controlled to a constant value. However, in the present embodiment, since the low-pressure pump 7 is driven by the engine as described above, If the rotation speed Ne changes, the discharge pressure of the low-pressure pump 7 also changes, and a constant pressure cannot be obtained. Therefore, the pressure feed control means 37
Is configured to store a discharge pressure coefficient with respect to the engine rotation speed Ne in a map M2, and to perform correction by multiplying the basic drive duty by the discharge pressure coefficient. The discharge pressure coefficient is set so as to increase as the discharge pressure decreases.

Next, the pressure feed control means 37 performs correction according to the pump efficiency of the high pressure pump 8. Since the lower the pump efficiency, the smaller the discharge amount, the drive duty must be increased. However, the pump efficiency of the high-pressure pump 8 changes according to the engine speed Ne. Thus, the pumping control means 37 stores the reciprocal of the pump efficiency with respect to the engine rotation speed Ne in the map M3, and multiplies the basic drive duty by using the reciprocal of the pump efficiency as a correction coefficient.

Further, the pressure feed control means 37 performs correction according to the fuel temperature. The fuel temperature changes according to external conditions such as air temperature, and the discharge amount also changes according to the fuel temperature. Therefore, a correction coefficient for the discharge amount with respect to the fuel temperature is stored in a map M4 using the fuel temperature as a parameter, and the correction coefficient for the fuel temperature is multiplied by the basic drive duty.

Then, in the pressure feed control means 37, the deviation ΔP between the detected rail pressure Pcr and the target rail pressure Pct (ΔP = Pcr
−Pct), and the control amount corresponding to the deviation ΔP is calculated as PI
The control is fed back to the corrected drive duty to determine the final drive duty. Then, by controlling the variable throttle valve 23 (PWM (pulse width modulation) control) with the determined drive duty, the amount of oil supply from the low-pressure pump 7 to the high-pressure pump 8 is adjusted. The amount of pressure feed to is adjusted.

On the other hand, the discharge control means 38 is means for controlling the injector control valve 4a based on the discharge judgment of the pressure feed / discharge judgment means 36, and controls the injector 4 so that the rail pressure after fuel injection becomes the target rail pressure Pct. The amount of fuel discharged by idle driving is adjusted. Specifically, first, from the map using the detected rail pressure Pcr and the deviation Pctes (Pctes = Pct−Pes) as parameters, the number of the injectors 4 to be idled, the number of idles, and the energization time to the injector control valve 4a are determined. Each is determined, and each determined value is multiplied by a correction coefficient for the fuel temperature. The correction coefficient is stored in a map using the fuel temperature as a parameter.

Then, a deviation ΔP (ΔP = Pcr−Pct) between the detected rail pressure Pcr and the target rail pressure Pct is calculated, and a control amount corresponding to the deviation ΔP is fed back to each of the corrected determined values by PI control. Then, the final number of used injectors 4, the number of idle shots, and the time for energizing the injector control valve 4a are determined. Then, the injector control valve 4a is controlled according to each determined value,
Thereby, the amount of fuel discharged from the common rail 3 is adjusted.

The injector control means 34 is a means for controlling the fuel injection start timing and the fuel injection amount by controlling the power supply start timing and the power supply time (pulse width) of the injector 4 to the injector control valve 4a. In the present fuel injection system 1, a plurality of injection modes (compression stroke injection, pilot injection, main injection, post-injection, etc.) are possible as described above, and the injector control means 34 operates the engine (engine rotation speed, accelerator speed). Opening etc.)
The injection timing and the injection time in each injection mode are set according to the conditions. The injection time is determined based on the target injection amount set according to the injection mode and the operating state of the engine, and the detected rail pressure Pcr. The start timing of energization is measured using a pulse output from the crank angle sensor 21.

Since the common rail fuel injection device according to one embodiment of the present invention is configured as described above, the rail pressure control is performed, for example, according to the flow shown in FIG. Hereinafter, referring to the flowchart,
The rail pressure control in the pressure accumulating internal combustion engine will be described. As shown in FIG. 5, when the previous injection is completed and the 27th pulse is input from the crank angle sensor 21 in the ECU 5, the ECU 5 calculates the engine speed Ne at that time and the final injection amount Qfin in the previous stroke. The target rail pressure Pct for the injection in the next stroke is determined (step S1).
00). Then, the rail pressure Pcr at the preceding stroke edge (at the time of inputting the 27th pulse) is detected (step S11).
0), the rail pressure Pes after the injection in the stroke is estimated from the detected rail pressure Pcr and the final injection amount Qfin in the previous stroke (step S120).

Next, a deviation Pctes (Pctes = Pct−Pes) between the target rail pressure Pct and the estimated rail pressure Pes after the injection is calculated, and if the deviation Pctes is positive, the routine proceeds to step S140, where the fuel is supplied to the common rail 3. (Step S
130). That is, first, the variable throttle valve 2 is obtained from the map M1 using the deviation Pctes and the detected rail pressure Pcr as parameters.
3 is determined (step S14).
0). Then, the determined basic drive duty is multiplied by the discharge pressure coefficient of the low-pressure pump 7 according to the engine speed Ne (step S150), and multiplied by the reciprocal of the pump efficiency of the high-pressure pump 8 according to the engine speed Ne (step S150). (S160), and a correction coefficient corresponding to the fuel temperature is multiplied (step S170).

Then, a deviation ΔP (ΔP = Pcr−Pct) between the detected rail pressure Pcr and the target rail pressure Pct is calculated (step S180), and a control amount corresponding to the deviation ΔP is PI-controlled to the corrected drive duty. To determine the final drive duty by feedback (Step S19)
0). Then, the variable throttle valve 23 is subjected to PWM control with the finally determined drive duty, and only the amount of fuel necessary to maintain the target rail pressure Pct is supplied from the low-pressure pump 7 to the high-pressure pump 8 (step S200).

On the other hand, in step S130, the deviation P
If ctes (Pctes = Pct-Pes) is equal to or less than zero, the process proceeds to step S210, and it is determined whether the deviation Pctes is zero or negative. When the deviation Pctes is zero, the current state is maintained without performing pumping or discharging, but when the deviation Pctes is negative, the process proceeds to step S220 to discharge the fuel from the common rail 3. That is, from the map using the deviation Pctes and the detected rail pressure Pcr as parameters, the number of used injectors 4,
The number of times of use and energization time are determined (step S220), and the determined values are multiplied by a correction coefficient according to the fuel temperature (step S230). Then, a deviation ΔP (ΔP = Pcr−Pct) between the detected rail pressure Pcr and the target rail pressure Pct is calculated (step S240), and a control amount corresponding to the deviation ΔP is fed back to each corrected value by PI control. Thus, the final number of used injectors 4, the number of times of use, and the energization time are determined (step S250). Then, the injector control valve 4a is controlled based on the finally determined number, the number of times of use, and the energizing time, and the injector 4 is idled (step S260).

Therefore, according to the present common rail fuel injection system, the rail pressure is compensated for while compensating for the discharge pressure of the low pressure pump 7 and the pump efficiency of the high pressure pump 8 which change according to the engine speed, and the discharge amount which changes according to the fuel temperature. Is controlled to the target rail pressure, so that there is an advantage that control accuracy is improved and energy loss due to wasteful work of the high-pressure pump 8 can be more efficiently prevented.

The variable throttle valve 23 for controlling the flow rate of the fuel supplied from the low-pressure pump 7 to the high-pressure pump 8 makes it possible to adjust the amount of fuel supplied to the common rail 3 on the low-pressure circuit side. There is an advantage that no adjusting means is required, and there is also an advantage that it is not necessary to connect a high-pressure circuit and a low-pressure circuit for adjusting the amount of pumping, so that the flow path configuration is not complicated.

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 operation of the variable throttle valve 23 provided between the low-pressure pump 7 and the high-pressure pump 8 is controlled so that the low-pressure pump 7
The amount of fuel fed to the common rail 3 is adjusted by adjusting the flow rate of fuel supplied from the pump to the high-pressure pump 8. However, the control valve according to the present invention is limited to a flow control valve such as the variable throttle valve 23. It is not something to be done. In other words, a discharge amount control valve communicating with the low pressure side is provided between the high pressure pump and the common rail, and the operation of the discharge amount control valve is controlled to adjust the discharge amount to the low pressure side. The amount of fuel pumped may be adjusted.
However, the control amount of the discharge amount control valve is the engine speed Ne.
The correction is made in accordance with the pump efficiency of the high-pressure pump and the fuel temperature, which change according to the pressure.

[0040]

As described above in detail, according to the common rail fuel injection system of the present invention, the pressure in the common rail is compensated for while compensating the change in the discharge amount of the high pressure pump with respect to the pump efficiency and the fuel temperature. Controls the operation of the control valve so that is maintained at the target pressure.
There is an advantage that the control accuracy is improved and energy loss due to wasteful work of the high-pressure pump can be more efficiently prevented.

Further, according to the common rail type fuel injection device of the present invention, the control valve is configured to control the amount of fuel supplied from the low pressure pump to the high pressure pump, and to the common rail on the low pressure circuit side. The control of the amount of fuel is possible, so there is an advantage that no high-pressure regulating means is required.Furthermore, since there is no need to connect a high-pressure circuit and a low-pressure circuit for adjusting the pumping amount, the flow path configuration is reduced. Another advantage is that it is not complicated.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of a common rail fuel injection device as one embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating a configuration of a high-pressure pump according to a common rail fuel injection device as one embodiment of the present invention, and FIG.
(B) is a diagram showing a state at the time of fuel discharge.

FIG. 3 is a timing chart showing a flow of rail pressure control according to the common rail fuel injection device as one embodiment of the present invention, and also shows a pulse input timing from a crank angle sensor and a rail pressure behavior. ing.

FIG. 4 is a diagram for explaining a method of determining a control amount of a variable throttle valve according to the common rail fuel injection device as one embodiment of the present invention.

FIG. 5 is a flowchart showing a flow of rail pressure control according to the common rail fuel injection device as one embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 3 common rail 4 injector (injection valve) 7 low pressure pump 8 high pressure pump 15 rail pressure sensor (pressure detection means) 23 variable throttle valve (control valve) 37 pressure control means 37 (control means)

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Setsuo Nishihara 5-33-8 Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation F-term (reference) 3G301 HA02 JA00 JA02 LB00 LB06 LB07 LB11 MA11 ND01 PB01Z PB08A PB08Z PE01Z PE03Z

Claims (2)

[Claims] 1. A common rail, which is connected to an injection valve for injecting fuel into each cylinder of an internal combustion engine and stores fuel in a pressurized state, and is driven by the internal combustion engine to pump fuel to the common rail to supply fuel in the common rail. A high-pressure pump for pressurizing, a control valve for controlling an amount of fuel supplied from the high-pressure pump to the common rail, a pressure detecting means for detecting a pressure in the common rail, and a pressure detected by the pressure detecting means. Control means for controlling the operation of the control valve so that the target pressure is attained. The control means controls the control valve based on a pump efficiency and / or a fuel temperature which change in accordance with a rotation speed of the internal combustion engine. A common rail fuel injection device configured to correct an amount. 2. A low-pressure pump for supplying fuel to the high-pressure pump, wherein the control valve is configured to control an amount of fuel supplied from the low-pressure pump to the high-pressure pump. The common rail fuel injection device according to claim 1.