KR20040045632A - an apparatus and the method for fuel injection pressure controling of common rail in diesel engine - Google Patents

Abstract

PURPOSE: A fuel injection pressure control device of a common rail diesel engine and a method thereof are provided to improve fuel efficiency in starting the engine and to reduce emission by injecting high pressure fuel after regulating the initial injection pressure of fuel into the low pressure according to the control signal from an ECU. CONSTITUTION: A fuel injection pressure regulating unit of a common rail diesel engine decreases initial injection pressure of fuel according to control signals from an ECU in starting the engine, and injects fuel at high pressure after passing the predetermined time. The fuel injection pressure regulating unit has a converting valve(410) controlled by the ECU to change flow of fuel, a pressure regulating valve(420) regulating pressure of fuel through the converting valve, a check valve(430) preventing counter flow of fuel, and a pressure regulating actuator controlled by the ECU to regulate initial injection pressure into low pressure and main injection pressure into high pressure.

Description

An apparatus and method for fuel injection pressure controling of common rail in diesel engine}

The present invention relates to a common rail diesel engine, and more particularly, in a vehicle in which the initial fuel injection and the main fuel injection are fuel injected at the same time by starting the engine, the starting initial fuel injection pressure is adjusted to low pressure and the main injection pressure is adjusted. The present invention relates to a fuel injection pressure control device for a common rail diesel engine and a method for improving fuel efficiency of a vehicle by reducing the pressure and reducing exhaust gas emissions.

The diesel fuel injectors used so far have used cam drives to obtain injection pressure. The principle is that the injection pressure increases with speed and the injection fuel amount increases accordingly. Such a device could only be used in practice with very low injection pressures. Unlike the cam driving method, the generation of the injection pressure and the injection process are completely separate from the common rail injection device used in a passenger car or a commercial vehicle. The advantage of this common rail system is to separate the pressure generation and injection of fuel in the engine design, thus freeing up combustion and adverb design. That is, since the fuel pressure and the injection timing can be adjusted according to the engine operating conditions using the engine map, high pressure injection is possible even when the engine rotation speed is low, so that complete combustion can be added. In addition, the pilot injection can further reduce the exhaust gas and noise, and the fuel injection curve is adjusted by the nozzle needle by the hydraulic control can be quickly adjusted until the end of the injection.

Accordingly, as shown in FIG. 1, the fuel stored in the fuel tank 10 is pumped by the high pressure pump 310 to fill the common rail 20 with fuel, and the pressure in the common rail 20 is in a vehicle operating state. The pressure sensor 160 of the detection device 100 is detected and controlled by the ECU 200 to a value set according to the engine speed and the load. The pressure in the common rail 20 is supplied to the injector 320 through a pipe, and the injection amount, injection rate, and injection timing are controlled according to a pulse sent to a three-way valve (not shown).

A very important function of the diesel engine's common rail injection system is injection rate control. The characteristics of this injection rate form and the combustion characteristics are very closely related. That is, as illustrated in FIG. 2, the fuel injection rate in the common common rail has a substantially rectangular shape. In order to satisfy the exhaust regulation, high pressure injection is essential, and the problem with the common rail injection system that realizes this is that the fuel injection rate is increased at a high pressure at the beginning of the injection, and thus fuel efficiency is not improved compared to the conventional mechanical pump. This has an excessive fuel injection rate in the initial injection, which creates an initial combustion environment due to the inherent compression of diesel engines, with the exception of the main injection timing injection rate, which affects the actual emission control (EMISSION).

Accordingly, an object of the present invention is to solve the above problems, in the common rail diesel engine, the initial injection at the fuel injection rate by the simultaneous injection pressure according to the initial injection pressure and the maximum injection pressure during the initial fuel injection It is an object of the present invention to provide a fuel injection pressure control device and a method for controlling a common rail diesel engine capable of controlling fuel consumption at low pressure to improve fuel efficiency and reduce emission of fuel gas.

1 is a configuration diagram of a fuel injection pressure control device of a conventional common rail diesel engine,

2 is a fuel injection control pattern diagram of a conventional common lane diesel engine,

3 is a block diagram of a fuel injection pressure control device of a common rail diesel engine according to an embodiment of the present invention,

4 is a flowchart illustrating a method for controlling fuel injection pressure of a common rail diesel engine according to an exemplary embodiment of the present invention.

5 is a configuration diagram of a fuel injection pressure control device for a common rail diesel engine according to an exemplary embodiment of the present invention;

6 is a flowchart illustrating a method for controlling fuel injection pressure of a common rail diesel engine according to an exemplary embodiment of the present invention.

7A is a fuel injection control pattern diagram of a common rail diesel engine according to an embodiment of the present invention;

b is a fuel injection control pattern diagram of a common rail diesel engine according to this embodiment of the present invention,

c is an injector valve control pattern diagram of a common rail diesel engine according to one embodiment of the present invention;

8 is a fuel injection control pattern diagram according to the present invention compared with the prior art.

<Description of Symbols for Main Parts of Drawings>

10: fuel tank 20: common rail

100: vehicle operation state detection device 110: engine speed detection unit

120: accelerator pedal opening degree detection unit 130: booster pressure detection unit

140: air temperature detector 150: cooling water temperature detector

160: rail pressure detection unit 200: ECU

310: high pressure fuel pump 320: injector

400: low pressure fuel control means 410: switching valve

420: pressure regulating valve 430: check valve

500: fuel pressure adjusting means

The present invention for achieving the above object,

In a common rail diesel engine, a fuel capable of injecting fuel at a high pressure after a predetermined time has elapsed after the initial injection pressure of the fuel is adjusted to a low pressure according to a control signal output from the ECU when the engine is started. It characterized in that it comprises a injection pressure adjusting means.

The fuel injection pressure adjusting means includes a switching valve controlled by the ECU for switching the flow of fuel, a pressure regulating valve for adjusting the pressure of the fuel applied through the switching valve, and a check valve for preventing the backflow of the fuel. Characterized in that the made up.

The fuel injection pressure adjusting means is characterized in that it comprises a pressure control actuator for duty control by the ECU to adjust the initial injection pressure and the main injection pressure to low and high pressure, respectively.

Another invention for achieving the above object,

Outputting a low pressure fuel injection control signal when the engine is started;

After outputting the low pressure fuel injection control signal in the step, it is characterized in that consisting of the step of outputting the high pressure fuel injection control signal after a predetermined time.

The fuel injection pressure adjusting means is controlled on / off by the fuel injection control signal output from the above.

The fuel injection pressure adjusting means is duty controlled by the fuel injection control signal output from the above.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

This embodiment is not intended to limit the scope of the present invention, but is presented by way of example only, the same reference numerals are assigned to the same parts as the conventional configurations in the drawings, and redundant descriptions are omitted.

3 is a configuration diagram of a fuel injection pressure control apparatus for a common rail diesel engine according to an embodiment of the present invention, and FIG. 4 is a flowchart illustrating a method for controlling fuel injection pressure of a common rail diesel engine according to an embodiment of the present invention. 5 is a configuration diagram of a fuel injection pressure control device for a common rail diesel engine according to an exemplary embodiment of the present invention, and FIG. 6 is a flowchart illustrating a method for controlling fuel injection pressure for a common rail diesel engine according to an exemplary embodiment of the present invention. 7 is a fuel injection control pattern diagram of a common rail diesel engine according to an embodiment of the present invention, b is a fuel injection control pattern diagram of a common rail diesel engine according to this embodiment of the present invention, c is One of the present invention is an injector valve control pattern diagram of a common rail diesel engine according to this embodiment, and FIG. 8 is a fuel injection control pattern diagram according to the present invention as compared with the related art.

As shown in FIG. 3 or FIG. 5, the common rail diesel engine includes low pressure injection control devices 400 and 500 for adjusting the initial injection pressure of the fuel to low pressure when the engine is started.

3 is a configuration diagram of a fuel injection pressure control device for a common rail diesel engine according to an exemplary embodiment of the present invention. The engine speed 110, the accelerator pedal opening degree 120, and the boost pressure vary according to a change in an operating state of the vehicle. A vehicle operating state detection device 100 provided at a change 130, an intake air temperature 140, a cooling water temperature 150, and a common rail at a predetermined position to detect a change in a vehicle operating state such as a rail pressure change 160;

Initial injection when starting the engine of the common rail diesel vehicle by receiving the engine speed, acceleration pedal opening degree, boost pressure change, intake air temperature, cooling water temperature, and rail pressure change detected by the vehicle operation state detection device 100. ECU 200 for controlling the pressure to low pressure and outputting a high pressure fuel injection control signal when a predetermined time elapses;

The high pressure pump 310 supplies the fuel stored in the fuel tank 10 at high pressure in synchronization with the control signal output from the ECU 200, and the fuel supplied in synchronization with the control signal output from the ECU 200. Injector 320 is injected into the engine, but the high-pressure fuel supplied from the high-pressure pump 310 to the injector 320, the low pressure to adjust the initial injection pressure to a low pressure at the initial start of the engine The injection regulator 400 is provided.

The low pressure injection control device 400 is a switching valve 410 for switching the flow of fuel in synchronization with the control signal output from the ECU 200, and a pressure control valve for adjusting the pressure of the supplied fuel to a predetermined pressure low 420 and the check valve 430 which prevents a backflow of fuel are provided.

In the above switching valve 410 is a three-way valve, the input side is coupled to the pipe line (unsigned) connected to the output side of the high-pressure pump 310, one end of the output side is coupled to the common rail 20 connected to the line (unsigned) ) And the other end is coupled to a pipe (unsigned) connected to the pressure control valve 420 input side.

The switching valve 410 is to switch the flow of fuel in synchronization with the switching on / off control signal output from the ECU 200, the valve position is positioned so that the other end of the input side and output side penetrates during the off control, At the time, the valve position is switched so that one end of the input side and the output side penetrates.

The pressure control valve 420 is a three-way valve, the input side is coupled to the other end of the output side of the switching valve 410, one end of the output side is connected to one end of the check valve 430, the other end is It is connected to the return line (unsigned) connected to the fuel tank 10.

One end of the check valve 430 is coupled to one end of the output side of the pressure control valve 420, the other end is coupled to the pipe (unsigned) connected to one end of the common rail 20 and the output side of the switching valve 410 Block the flow of fuel back to the other end.

5 is a configuration diagram of the injection pressure control device for a common rail diesel engine according to an embodiment of the present invention, in which a fuel pressure regulating actuator 500 connects a high pressure pump 310 and a common rail 20. And the injection pressure at the time of initial injection of the fuel supplied from the high pressure pump 310 to low pressure, and the injection pressure at the main injection to high pressure according to the duty control signal output from the ECU 200. Supply to the common rail 20 by adjusting.

An example will be described with reference to FIGS. 4, 6, 7 and 8 attached to the control method of the injection pressure regulation control apparatus of the common rail diesel engine having the above-described configuration.

[First Embodiment]

4 is a flowchart illustrating a method for controlling injection pressure control of a common rail diesel engine according to an exemplary embodiment of the present invention. When a driver starts an engine to drive a vehicle, the vehicle operation state detecting apparatus 100 changes the operating state of the vehicle. The engine speed, the accelerator pedal opening degree, the boost pressure change, the intake air temperature, the coolant temperature, and the rail pressure change that are varied according to the detection are detected (S100).

Accordingly, the ECU 200 is configured to receive a predetermined number of engine speeds, accelerator pedal openings, boost pressure changes, intake air temperature, cooling water temperature, rail pressure changes, etc. detected and applied by the vehicle operation state detection device 100. When the control signal is output, the vehicle operating state detecting apparatus 100 is provided at a predetermined engine speed, accelerator pedal opening degree, boost pressure change, intake air temperature, cooling water temperature, and common rail predetermined positions to output a rail pressure change, and the like. do.

Accordingly, the ECU 200 receives the engine tank speed, the accelerator pedal opening degree, the boost pressure change, the intake air temperature, the coolant temperature, and the rail pressure change that are detected and applied by the vehicle operation state detection device 100. A predetermined control signal for injecting the fuel stored in the 10 into the engine is output (S110).

The control signal output from the ECU 200 is a high pressure pump driving, low pressure control, injector control signal.

That is, when the engine is started, the ECU 200 outputs a low pressure injection control signal so as to perform initial injection at low pressure as shown in a of FIG. 7 and simultaneously operates a timer.

Accordingly, the high pressure pump 310 shown in FIG. 3 supplies the fuel stored in the fuel tank 10 at high pressure in synchronization with a control signal applied from the ECU 200, and the injector 320 supplies fuel. It maintains the drive 'on' state as shown in FIG. 7C to inject into the engine.

In addition, the ECU 200 maintains the 'off' state of the switching valve 410 provided in the low pressure injection control device 400 shown in FIG. 3 as shown in FIG.

At this time, the fuel supplied from the high pressure pump 310 is supplied to the pressure control valve 420 via the switching valve 410 provided in the low pressure injection control device 400 as shown in FIG.

The pressure regulating valve 420 lowers the supplied high pressure fuel to a predetermined pressure to supply the common rail 20 through the check valve 430, and the fuel supplied to the common rail 20 supplies the injector 320. Through the engine.

After the fuel lowered to a predetermined pressure is supplied from the pressure regulating valve 420 to the check valve 430, the remaining fuel is supplied to the fuel tank 10 through a conduit (unsigned) connected to the fuel tank 10. Is returned.

After that, the ECU 200 determines whether a predetermined time for ending the initial injection has elapsed (S120).

When it is determined that a predetermined time elapses from the initial injection, the ECU 200 outputs a high pressure injection control signal such that the main injection is performed at high pressure as shown in FIG. 7A (S130).

That is, the ECU 200 outputs a control signal for main injection immediately after the initial injection, as shown in a of FIG. 7, at this time, the switching valve 410 provided in the low pressure injection control device 400. ) Is switched from an 'off' state to an 'on' state as shown in b of FIG. 7, and the injector 320 remains 'on' as shown in c of FIG. 7.

As the switching valve 410 is switched from the "off" state to the "on" state, one end of the output side of the switching valve 410 is opened, the other end is closed, the fuel supplied from the high-pressure pump 310 Is supplied to the common rail 20 in a high pressure state is injected into the engine through the injector 320 high pressure.

8 is a diagram comparing a conventional fuel injection control signal a with a fuel injection control signal b of the present invention.

After repeating the above-described injection process until the engine speed is stably maintained, the engine 200 maintains the stable idling state, and the ECU 200 maintains the high pressure injection state as in the prior art.

Second Embodiment

FIG. 5 is a flowchart illustrating a method for controlling injection pressure of a common rail diesel engine according to an exemplary embodiment of the present invention. When the engine is started, the vehicle operating state detecting apparatus 100 may change an engine speed that varies according to a change in an operating state of a vehicle. The accelerator pedal opening degree, the boost pressure change, the intake air temperature, the cooling water temperature and the rail pressure change are detected (S200).

Accordingly, the ECU 200 receives a predetermined number of engine speeds, accelerator pedal openings, boost pressure changes, intake air temperature, cooling water temperature, and rail pressure change detected by the vehicle operation state detection device 100. When the control signal is output, the vehicle operating state detecting apparatus 100 is provided at a predetermined engine speed, accelerator pedal opening degree, boost pressure change, intake air temperature, cooling water temperature, and common rail predetermined positions to output a rail pressure change, and the like. do.

Accordingly, the ECU 200 receives the engine tank speed, the accelerator pedal opening degree, the boost pressure change, the intake air temperature, the coolant temperature, and the rail pressure change that are detected and applied by the vehicle operation state detection device 100. Outputs a predetermined control signal for injecting fuel stored in the 10 into the engine (S210).

Control signals output from the ECU 200 are high pressure pump driving, low pressure duty control, and injector control signals.

That is, when the engine is started, the ECU 200 outputs a low pressure injection duty control signal to operate the timer at the same time as the initial injection is performed at low pressure as shown in a of FIG.

Accordingly, the high pressure pump 310 shown in FIG. 5 supplies the fuel stored in the fuel tank 10 at high pressure in synchronization with the control signal applied from the ECU 200, and the injector 320 supplies fuel. It maintains the drive 'on' state as shown in FIG. 7C to inject into the engine.

Subsequently, the fuel supplied from the high pressure pump 310 is applied to the common rail 20 at a predetermined low pressure via the pressure regulating actuator 500 as shown in FIG. 5.

Therefore, the ECU 200 determines whether the initial fuel low pressure injection time has elapsed by comparing the timer operating time according to the initial injection (S220).

When it is determined that the initial fuel low pressure injection time has elapsed, the ECU 200 outputs a high pressure injection duty control signal for injecting the main fuel injection at high pressure as shown in FIG. 7A (S230).

That is, as shown in FIG. 7A, the ECU 200 immediately outputs a duty control signal for the main injection when the initial injection is finished, and supplies the fuel supplied from the high pressure pump 310 to the common rail in a high pressure state. High pressure injection into the engine to the injector 320 through 20.

8 is a diagram comparing a conventional fuel injection control signal a with a fuel injection control signal b of the present invention.

After repeating the above-described injection process until the engine speed is stably maintained, the engine 200 maintains the stable idling state, and the ECU 200 maintains the high pressure injection state as in the prior art.

As a result, by improving the injection rate of the common rail diesel engine, it is possible to improve the engine start initial fuel efficiency and to reduce the emission of exhaust gas due to the reduction of the fuel amount.

As described above, the present invention can improve the fuel efficiency at the start of the engine by controlling the initial injection rate to a low pressure at the fuel injection rate by the simultaneous injection pressure according to the initial injection pressure and the maximum injection pressure during the initial fuel injection. Since the fuel consumption can be reduced, there is an effect of reducing the generation of exhaust gas.

Claims (6)

In a common rail diesel engine, a fuel capable of injecting fuel at a high pressure after a predetermined time has elapsed after the initial injection pressure of the fuel is adjusted to a low pressure according to a control signal output from the ECU when the engine is started. Injection pressure control device of a common rail diesel engine comprising a injection pressure adjusting means. The fuel injection pressure regulating means of claim 1, wherein the fuel injection pressure regulating means is controlled by an ECU to switch the flow of fuel, a pressure regulating valve to adjust the pressure of the fuel applied through the switching valve, and to prevent the backflow of the fuel. Injection pressure control apparatus of a common rail diesel engine comprising a check valve. 2. The common rail diesel engine injection pressure control according to claim 1, wherein the fuel injection pressure adjusting means includes a pressure regulating actuator configured to be duty controlled by the ECU to adjust the initial injection pressure and the main injection pressure to low pressure and high pressure, respectively. Device. Outputting a low pressure fuel injection control signal when the engine is started; And outputting a high pressure fuel injection control signal when a predetermined time elapses after outputting the low pressure fuel injection control signal in the step. The injection pressure control method of claim 4, wherein the fuel injection pressure adjusting means is controlled on / off by the output fuel injection control signal. The injection pressure control method of claim 4, wherein the fuel injection pressure adjusting means is duty-controlled by the output fuel injection control signal.