JP3508512B2 - Fuel injection device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device for injecting high pressure fuel supplied from a common rail.

[0002]

2. Description of the Related Art Conventionally, as disclosed in Japanese Unexamined Patent Publication No. 5-71438, fuel in a fuel tank is accumulated in a high pressure state by a fuel pump in a pressure accumulating chamber called a common rail, which is common to each injector. There is known a device that supplies high-pressure fuel to an injector corresponding to a cylinder to inject fuel in a high-pressure state.

In the fuel injection device described in the above publication, the back pressure of the needle nozzle provided in the injector is switched between two levels during fuel injection, and fuel injection at a low injection rate and a high injection rate is performed by one fuel injection. I am able to

[0004]

As a nozzle structure adopted in a conventional injector, a VCO shown in FIG. 7 is used.
(Valve covered orifice) A so-called nozzle is known.

In the VCO nozzle structure shown in FIG. 7, the injection hole 14 is formed in the seat portion 16 which is the contact portion between the nozzle body 12 and the needle 13, and the sack 15 found in the general nozzle shown in FIG. There is no fuel, and fuel remains in the sack 15 after one fuel injection, and the fuel remaining in the sack 15 is sucked into the combustion space in the intake stroke of the next engine, and the emission increases when the engine burns.
HC is Kuku to occur a phenomenon that particulate matter can be caused to increase, there is a tendency that the VCO nozzle is employed in recent years.

However, in the VCO nozzle shown in FIG. 7, there is a region called a choke region of the nozzle immediately after the needle 13 is opened and immediately before it is closed, so atomization of the spray is extremely deteriorated when passing through this region. Will end up. In the nozzle of the type shown in FIG. 6, when the distance between the seat portions 16 immediately after the valve opening and immediately before the valve closing is small, the pressure once drops when the high pressure fuel on the upstream side passes through the seat portion 16, but Since it is in the sack 15 on the downstream side of the portion 16 and the distance required to recover the pressure can be secured, the fuel actually injected from the nozzle returns to the high pressure state.

On the other hand, since the VCO nozzle has the nozzle injection hole 14 in the sheet portion, the nozzle of the type shown in FIG. 6 does not sufficiently recover the pressure, resulting in poor atomization. In more explanation, atomization nozzle hole 14 or these injection speed of fuel it is better fast, thus the fuel pressure is higher atomization in the nozzle hole is improved. In the VCO nozzle, the speed at which the fuel pressure becomes the same on the upstream side and the downstream side across the seat portion at a stage where the distance between the seat portions immediately after opening the valve or immediately before closing the valve is narrower than that of the nozzle of FIG. 6 type. Can be said to be late.

Further, in the fuel injection device having the common rail, the fuel pressure supplied to the injector is 100.
Since the pressure is considerably high on the order of MPa, the needle 13
The injection amount per unit time in the choke region immediately after the valve opening and immediately before the valve closing, that is, the fuel injection rate becomes considerably large. Therefore, there is a possibility that it is difficult to obtain a good air-fuel mixture because the amount of fuel that is not sufficiently atomized as described above is considerably increased.

In view of the above problems, it is a technical object of the present invention to reduce the injection amount of insufficiently atomized fuel immediately after the fuel injection of an injector or immediately before the fuel injection.

[0010]

In order to achieve the above-mentioned object, the invention according to claim 1 provides a fuel supply pump.
Equipped with a common rail for accumulating high-pressure fuel supplied from
The high pressure fuel accumulated in the common rail is delivered to each cylinder.
The fuel injection system for morphism injection fuel under high pressure is supplied to the injector to respond to said injector nozzle
Fuel is injected into the contact area between the needle body and the needle.
High-pressure fuel inside the common rail with injection holes
An electromagnetic relief valve that returns a part of the
Before the start of fuel injection by the electromagnetic relief valve
Note: Lower the fuel pressure on the common rail, then
Increase fuel pressure by supply pump, and increase fuel pressure
The fuel injection was started at the stage .

Further, in the fuel injection device according to the second aspect, the high pressure fuel supplied from the fuel supply pump is accumulated in pressure.
Bei to give a child Monreru, it has been accumulated in the common rail
High-pressure fuel is supplied to the injectors corresponding to each cylinder to
In fuel injection system for injecting fuel in a pressurized state, said Lee
The injector has a contact part between the nozzle body and the needle.
Has a nozzle hole through which fuel is injected.
Electromagnetic relay that returns a portion of the high-pressure fuel in the rail to the fuel tank.
A leaf valve is installed so that the electromagnetic release can be performed before the end of fuel injection.
Open the fuel pressure reduction of the common rail with the solenoid valve.
Fuel injection after the common rail fuel pressure starts to be reduced.
It was so that to end the elevation.

In the fuel injection device according to claim 3 , the fuel is
E Bei co mode <br/> Nreru for accumulating high-pressure fuel supplied from the supply pump, the high-pressure fuel accumulated in the common rail
Is supplied to the injectors corresponding to each cylinder,
In fuel injection device for injecting fuel, the injectors
The fuel on the contact area between the nozzle body and the needle.
Is formed in the common rail.
Electromagnetic relief bar that returns a portion of the high-pressure fuel inside to the fuel tank
Valve is installed, and the electromagnetic relief valve is installed before starting fuel injection.
Reduce the common rail fuel pressure by
Fuel of the common rail by the fuel supply pump
Fuel injection is started at the stage of increasing the pressure and then
The electromagnetic pressure relief valve reduces the common rail fuel pressure.
It starts decreasing, and to terminate the fuel injection after lowering the start of the co Monreru fuel pressure. A fuel injection device characterized by the above.

[0013]

[0014]

According to the first aspect of the invention, since the pressure of the fuel supplied from the pressure accumulating chamber is changed during the fuel injection, the nozzle choke period immediately after the start of fuel injection or immediately before the end of fuel injection. It is possible to suppress the injection amount of the insufficiently atomized fuel injected into the fuel cell.

[0015] In claim 1, it is possible to suppress a large amount discharge of insufficient fuel atomization immediately after jetting start.

[0016] In claim 2, it is possible to suppress a large amount discharge of insufficient fuel atomization jetting just before the end.

In the fuel injection device according to the third aspect, it is possible to suppress a large amount of the fuel whose atomization is insufficient during both the period immediately after the start of the injection and immediately before the end of the injection.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. When the present invention is applied to the fuel injection device with a common rail equipped with the injector of the VCO nozzle structure described above, the desired effect can be obtained particularly well. Therefore, a fuel injection device with a common rail equipped with the injector of the VCO nozzle structure is provided. Explain to the premise.

FIG. 1 is an overall configuration diagram showing a fuel injection device with a common rail according to the present invention. In FIG.
An injector 1 is provided corresponding to the combustion chamber of each cylinder of the engine. Note that one of them is shown in FIG.
Only one is shown and the rest are omitted. The injection hole of the injector 1 is opened and closed by the vertical movement of the needle 13, as shown in FIG. In this embodiment, since the tip of the injector has a VCO nozzle structure, a problem due to the remaining fuel after fuel injection can be prevented. The injector 1 is provided with a conduit for returning a part of the fuel leaked or supplied from the common rail 3 to the fuel tank. Figure 1
The middle 2 is a fuel supply pump for supplying the fuel in the fuel tank 6 in a high pressure state to the common rail 3 via the high pressure pipe 7. A pump control valve 11 is means for adjusting the amount of fuel supplied to the common rail in accordance with a control signal from an ECU (electronic control unit) 8. Although the fuel in FIG. 1, <br/> fuel tank 6 directly from the fuel supply pump 2 are supplied, between the fuel tank 6 and the fuel supply pump 2 for the fuel feed A feed pump may be provided.

[0020] 3 is a common rail, which accumulates the fuel Sapuraipo <br/> emissions flop 2 or we supplied high-pressure fuel,
Each Injector 1 is connected via a high-pressure fuel pipe 4. Reference numeral 10 is a pressure sensor for detecting the pressure in the common rail 3, and its pressure signal is the ECU 8
It is designed to be input to. 5 is an electromagnetic relief valve, fuel tank part of the fuel in the common rail 3
It is a valve for returning to 6, and the pressure in the common rail 3 can be adjusted by adjusting the electromagnetic relief valve 5. The electromagnetic relief valve 5 is an electromagnetically driven valve driven by a control signal from the ECU 8.

Reference numeral 8 denotes an ECU, to which output signals of various sensors including the pressure sensor 10, for example, an engine speed sensor and an accelerator opening sensor are input. E
The CU 8 is composed of an electronic circuit unit including a well-known CPU, bus, ROM, RAM, and interface circuit. Then, the ECU 8 outputs a control signal for driving the valve to the electromagnetic relief valve 5 at an appropriate timing based on information from various sensors, and the electromagnetic relief valve 5 operates based on the drive control signal. Also,
Since the injector 1 has a solenoid valve (not shown) for causing the needle 13 to move up and down, the ECU 8 drives the injector 1 by turning the solenoid valve on and off based on information from various sensors. The control signal of is also output. Further, the ECU 8 also outputs a control signal to the pump control valve 11 that controls the amount of fuel supplied to the common rail 3 of the fuel supply pump 2. 9 is ED
U (Electronic Driving Unit) is a drive circuit for driving the solenoid valve of the injector 1. Arrow lines in FIG. 1 represent various signal lines.

Next, the manner of control of fuel injection in the fuel injection device of FIG. 1 will be described with reference to FIGS. 2 to 5. 2 to 5 show the passage of time of the common rail pressure signal, the injector 1 control command signal, the electromagnetic relief valve 5 control signal, and the injection pressure signal in the injection cycle, respectively. Common rail pressure signal is pressure sensor 1
The injector 1 control command signal and the electromagnetic relief valve control signal are ON-OFF signals output from the ECU 8.

FIG. 2 shows an example of reducing insufficiently atomized fuel injection immediately after the start of fuel injection, in which the pressure of the common rail 3 is driven by the control signal from the ECU 8 to drive the electromagnetic relief valve 5 immediately before the start of fuel injection. Depressurize once. Therefore, the injection pressure is relatively low at the start of injection,
Injection start time of the injection rate is low, it is because it corresponds to the time in Nozuruchi Yoku area of the valve opening initial in VCO nozzles, it is possible to minimize the atomization insufficient atomization occurs. The pressure of the common rail 3 is once reduced by the electromagnetic relief valve 5, and then rapidly increased to the pressure required for injection by the fuel supply pump 2 during injection. The rapid post Nozuruchi Yoku region transmission of VCO nozzle by pressure increase of the common rail pressure good atomization of atomization is generated by the original high-pressure injection.

FIG. 3 shows an example of improving the spray state immediately before the end of injection. Until the end of injection, the pressure of the common rail 3 is kept high and the atomization of the spray by the high-pressure injection is kept good. Immediately before the end of injection, the pressure of the common rail 3 is reduced by the electromagnetic relief valve 5. Closing just before becomes Nozuruchi Yoku region in VCO nozzles, although spray This state is deteriorated, the fuel injection rate is lowered by the decompression of the common rail 3 pressure, the amount of poor spray atomization Nozuruchi Yoku region Can be reduced. Particularly, the spray at the end of fuel injection is important because it affects the generation of black smoke in the latter stage of combustion. After the fuel injection is completed, the fuel supply pump 2 increases the pressure of the common rail 3 until it reaches a predetermined pressure in preparation for the next injection.

FIG. 4 shows an example in which the fuel injection pressure is changed both immediately after the start of fuel injection and immediately before the end of fuel injection, which can be achieved by a combination of the controls of FIGS. 2 and 3.

FIG. 5 also shows the VCO nozzle at the start and end of injection.
Reducing the injection rate of Nozuruchi Yoku region is an example, FIG. 2
Therefore, unlike FIG. 4, the pressure of the common rail 3 before the start of injection is set lower than the high-pressure fuel pressure required during the middle of injection, that is, during injection. The pressure of the common rail 3 at this time may be based on the control of the fuel supply pump 2, or the electromagnetic relief valve 5 at the end of injection in the previous cycle.
The result of the control may be used. Spraying of adverse effects of Nozuruchi Yoku region of VCO nozzles for the low injection rate at the start of injection can be minimized. Immediately after the start of injection, the pressure of the common rail 3 is increased by the fuel supply pump 2, whereby high-pressure injection is achieved in the middle of injection, and good spray is obtained. Immediately before the end of injection, the pressure is reduced by the pressure electromagnetic relief valve 5 of the common rail 3. Since the decompression by the injection rate of the common rail 3 pressure by the electromagnetic relief valve 5 is lowered, it is possible to suppress the amount of poor spray atomization Nozuruchi Yoku region. The common rail 3 pressure after injection is maintained at the initial low pressure.

As described above, according to the embodiment of the present invention, the injection rate pattern can be changed by controlling the electromagnetic relief valve 5 during the injection period, so that the exhaust gas can be improved and the combustion noise can be reduced. Further, the fuel injection control patterns of FIGS. 2 to 5 may be appropriately changed according to the operating state of the internal combustion engine, that is, during low load operation, medium load operation, and high load operation. In the embodiment of the present invention, the VCO
Although the description has been given on the premise of the fuel injection device having the nozzle structure, the present invention may be applied to the fuel injection device having the nozzle with the sack 15 as shown in FIG.

[Brief description of drawings]

FIG. 1 is an overall view of a fuel injection device with a common rail according to the present invention.

FIG. 2 is an explanatory diagram of control of fuel injection. (Control at the start of injection)

FIG. 3 is an explanatory diagram of control of fuel injection. (Control at the end of injection)

FIG. 4 is an explanatory diagram of control of fuel injection. (Control at start and end of injection)

FIG. 5 is an explanatory diagram of control of fuel injection. (Control at start and end of injection)

FIG. 6 is a sectional view showing a nozzle structure at the tip of the injector.
(With sack)

FIG. 7 is a sectional view showing the nozzle structure at the tip of the injector.
(VCO nozzle)

[Explanation of symbols]

1 Injector 2 Fuel Supply Pump 3 Common Rail 4 High Pressure Fuel Pipe 5 Electromagnetic Relief Valve 6 Fuel Tank 7 High Pressure Pipe 8 ECU (Electronic Control Unit) 9 EDU (Electronic Driving Unit) 10 Pressure Sensor 11 Pump Control Valve 12 Nozzle Body 13 Needle 14 Injection Hole 15 sack 16 seat

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) F02M 55/02 350 F02M 47/00 F02M 63/02 F02D 41/38

Claims (3)

(57) [Claims] 1. High pressure supplied from a fuel supply pump
Equipped with a common rail for accumulating fuel
Accumulated high-pressure fuel to the injector corresponding to each cylinder
Contact of the feed with a fuel injection device for morphism injection fuel at high pressure state, the injector includes a nozzle body and needle
An injection hole for fuel injection is formed in the contact area,
Return part of the high-pressure fuel in the common rail to the fuel tank
An electromagnetic relief valve is provided so that the power can be
The magnetic relief valve increases the fuel pressure on the common rail.
The fuel supply pump to lower the fuel
A fuel injection device, characterized in that the pressure is increased and the fuel injection is started at the stage of increasing the fuel pressure . 2. High pressure supplied from a fuel supply pump
The co-Monreru for accumulating the fuel Bei For example, in the common rail
Accumulated high-pressure fuel to the injector corresponding to each cylinder
Contact of the fuel injection device that injects fuel under high pressure is supplied to said injector includes a nozzle body and needle
An injection hole for fuel injection is formed in the contact area,
Return part of the high-pressure fuel in the common rail to the fuel tank
An electromagnetic relief valve is provided to enable the above-mentioned electricity before the end of fuel injection.
A magnetic relief valve reduces the common rail fuel pressure.
Pressure is started and after the common rail fuel pressure is reduced.
A fuel injection device characterized in that it is configured to terminate fuel injection. 3. High pressure supplied from a fuel supply pump
The co-Monreru for accumulating the fuel Bei For example, in the common rail
Accumulated high-pressure fuel to the injector corresponding to each cylinder
Contact of the fuel injection device that injects fuel under high pressure is supplied to said injector includes a nozzle body and needle
An injection hole for fuel injection is formed in the contact area,
Return part of the high-pressure fuel in the common rail to the fuel tank
An electromagnetic relief valve is provided so that the power can be
A magnetic relief valve reduces the common rail fuel pressure.
The fuel supply pump and then the
Fuel injection at the stage of increasing the fuel pressure of the rail
Then, the electromagnetic relief valve
A fuel injection device, characterized in that the fuel injection device is configured to start the decrease of the fuel pressure of the common rail and to finish the fuel injection after the decrease of the fuel pressure of the common rail is started .