JP2721747B2 - Water injection device - Google Patents

Description

It relates BACKGROUND OF THE INVENTION (FIELD OF THE INVENTION) The present invention of water injection Diesel engine for reducing NO _x.

(Prior Art) FIG. 3 is a diagram of a conventional water injection device, and FIG. 4 is a characteristic curve diagram thereof. Fuel from the high-pressure pump 10 passes through the high-pressure passage 12 through the discharge valve 14 and is injected from the injection nozzle 20 into the combustion chamber of the internal combustion engine and burns.

Here, the injection nozzle 20 is constituted by an automatic valve having a needle valve 21 whose valve opening pressure is set by a spring 22. NO when burning fuel
Water whose pressure has been increased to a pressure lower than the valve opening pressure of the injection nozzle 20 by a hydraulic pump (not shown) to suppress the generation of _x
By opening the solenoid valve 31 during the period when the high-pressure pump 10 is not operating, 30 flows backward through the check valve 32 from the water injection point 40 of the high-pressure fuel passage 12 into the high-pressure fuel passage 12. I have.

At this time, since the high-pressure fuel passage 41 on the injection nozzle 20 side from the water injection point 40 has reached a dead end, water flows in the direction of the high-pressure pump 10. The fuel displaced by this water inflow returns from the check valve 13 provided on the high-pressure pump 10 side of the high-pressure fuel passage 12 to the fuel supply section 11 through the high-pressure pump 10, where the check valve 13 The valve is opened at a pressure lower than the valve opening pressure of the injection nozzle 20. When the required amount of water has flowed in, the solenoid valve 31 is closed and the flow of water is stopped.

In the next cycle, the high pressure pump 10 operates and the fuel is discharged
14, when injected from the injection nozzle 20 through the high-pressure fuel passage 12, because water is injected in the middle of the high-pressure fuel passage 12,
The injection is as shown in FIG.

That is, first, the fuel in the high-pressure fuel passage 41 downstream from the water injection point 40 is injected as shown in FIG. 4A, and then the injected water is injected as shown in FIG. Fuel passage
Twelve fuels C are injected. Since water is added in the course of fuel injection into a result the fuel chamber, generated of the NO _x is kept low.

(Problems to be Solved) However, in the prior art, since in the course of fuel injection occurs is timing B only water and slide into increasing the amount of injected water further reduced purposes NO _x, a combustion chamber Of the internal combustion engine itself, and the rotation of the internal combustion engine itself becomes unstable.

For this reason, the amount of water injected is limited, and NO _x cannot be reduced below a certain value.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the conventional apparatus, to secure a minimum fuel E required to continue combustion even during water injection, and to ensure stable engine performance without interruption of combustion. To provide.

(Means for Solving the Problems) The water injection device of the present invention has a high-pressure pump for pumping fuel and an injection nozzle for injecting fuel from the high-pressure pump into a cylinder. In a device for injecting water into the high-pressure fuel passage to the injection nozzle, a high-pressure fuel passage 12, 12 'between the high-pressure pump 10 and the injection nozzle 20 is provided.
A bypass fuel passage 50 provided to bypass the inside water injection portion 12 ′, a check valve 51 provided in the bypass fuel passage 50 and allowing only the flow of fuel from the high-pressure pump side to the injection nozzle; It is characterized in that it has a throttle portion 52 or a narrow tube portion provided in the fuel passage 12 'and downstream near the branch point 53 of the bypass fuel passage 50.

(Operation) If the solenoid valve 31 is opened when the high-pressure pump 10 is not operating, pressurized water flows into the high-pressure injection pipe from the water injection point 40. Injection nozzle in line 41, check valve 51 in line 50
Is provided, the front pressurized water pushes the check valve 13 of the high-pressure pump 10 to open and flow back through the pipe 12 ', and water is injected into the pipe.

Next, the high-pressure pump 10 starts operating and discharges fuel oil, and the fuel branches off from the branch point 53 to the pipelines 50 and 12 '. Then, first, the fuel in the pipeline 41 is injected as shown in FIG.
Next, water and fuel are simultaneously injected from the pipes 12 'and 50 as shown in E and D of FIG. 2, and when the injection of the E and D parts is completed, only the fuel flows through the pipes 12' and 50 as shown in C. (Embodiment) An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is an overall view of the first embodiment, and FIG. 2 is an injection characteristic diagram of the injection nozzle.

The high-pressure fuel passage 41 and the high-pressure fuel passage 12 are connected to each other to form a water injection portion 12 '.
A bypass fuel passage 50 for bypassing the fuel cell. The passage 50
A branch point between the path and the passage 12 'is a branch point 53. Further, a check valve 51 is provided in the bypass fuel passage 50. A throttle 52 is provided between the branch point 53 and the water injection point 40.

The flow path resistance of the throttle 52 in FIG. 1 is equal to or larger than the flow path resistance of the check valve 51. Therefore, during fuel injection, fuel or water flows out of both flow paths 12 ', 50 without closing the check valve 51.

High-pressure fuel passage 1 from junction 53 to water injection point 40
The volume in 2 'is larger than the maximum value of the water to be injected.

 Next, the operation of the above embodiment will be described.

When water is injected from the water injection point 40 during a period when the high-pressure pump 10 is not operating, no water is injected because the check valve is provided in the bypass fuel passage 50, and the high-pressure fuel It is injected into the passage 12 '.

Next, when the high-pressure pump 10 operates during engine operation, fuel and water are injected as shown in FIG. That is, first, the fuel in the high-pressure fuel passage 41 is injected as shown in FIG.

Next, the water in the high-pressure fuel passage 12 'upstream of the water injection point 40 and the fuel in the bypass fuel passage 50 are both injected as indicated by D and E in FIG. After the injection of the injected water is completed, only the fuel is injected as shown in FIG. 2C as in the conventional example. Therefore, there is no longer a period in which only water is injected as in the conventional example, and the minimum amount of fuel E necessary for continuing combustion even during water injection is secured, so that stable operation of the engine is ensured without interruption of combustion. Is done.

Second Embodiment A similar function and effect can be obtained by using a thin tube in a part of the high-pressure fuel passage 12 'near the branch point 53 instead of the throttle 52 of FIG. can get.

(Effect of the Invention) Since the water injection device of the present invention is configured as described above,
As shown in FIG. 2, the minimum amount of fuel E required to continue combustion even during water injection is secured, stable operation of the engine without interruption of combustion can be ensured, and as a result, the water injection amount is limited to the conventional limit. can also be increased from the value, it is possible to reduce the emissions of NO _x.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 and 2 relate to the present invention, FIG. 1 is an overall view of the first embodiment, FIG. 2 is a characteristic diagram of the injection nozzle, and FIGS.
FIG. 3 is a conventional example, FIG. 3 is a drawing corresponding to FIG. 1, and FIG. 4 is a drawing corresponding to FIG. 10 high-pressure pump, 12 high-pressure fuel passage, 20 injection nozzle, 40 water injection point, 50 bypass fuel passage, 51
... check valve, 52 ... throttle, 53 ... bypass branch point.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Mataji Tateishi 1-1, Akunoura-cho, Nagasaki-shi, Nagasaki Prefecture Mitsubishi Heavy Industries, Ltd. Nagasaki Research Laboratory (56) References 1983-163634 (JP, U)

Claims (1)

(57) [Claims] 1. A high-pressure pump for feeding fuel and an injection nozzle for injecting fuel from the high-pressure pump into a cylinder, and water is injected into a high-pressure fuel passage to the injection nozzle during a period when the fuel pump is not operating. The high pressure pump (1
0) and the high-pressure fuel passage (12) (1) between the injection nozzle (20)
A bypass fuel passage (50) provided so as to bypass the water injection part (12 ') inside the bypass fuel passage (2');
A check valve (51) provided in the high pressure fuel passage (12 ') and allowing the fuel flow from the high pressure pump side to the injection nozzle; and a branch point (53) of the bypass fuel passage (50) in the high pressure fuel passage (12'). A water injection device comprising a throttle portion (52) or a narrow tube portion provided near and downstream.