JP3021216B2 - Water 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 water injection device for a diesel engine.

[0002]

Although BACKGROUND OF THE INVENTION Diesel engine is widely used as a prime mover for the high thermal efficiency, is the harmful CO in the exhaust component, CO _2, HC, NO _X and the like as major issue is included in a large amount ing. So then the system will be described to reduce harmful NO _X injected by adding water to the fuel. Referring first to FIG. 3, the fuel valve 1 is a fuel valve main body, 2 is a nozzle tip, 3 is an injection hole, 4 is a fuel inlet fitting, 5 is a fuel oil passage in the fuel valve, and 6 is a fuel oil in the presser fitting. 8 is a needle valve oil reservoir, 9 is a needle valve, 10 is a needle valve spring receiver, 11 is a spring, and 12 is a valve opening pressure adjusting hardware for the needle valve. The valve opening pressure can be changed. Next, the water injection system will be described. 13 is a water injection metal fitting, 14 is a check valve, 15 is a check valve spring, 16 is a fuel valve inner water path, 17 is a presser foot inner water path, and 18 is a nozzle tip fuel oil path. . The fuel oil passage 6 in the presser foot and the water passage 17 in the presser foot are joined by a joining passage 40, and also communicates with the fuel oil passage 18 in the nozzle tip via the check valve 14.

Next, a system for supplying fuel and water to the fuel valve will be described. 21 is a fuel tank, 22 is a fuel supply pump, 23 is a fuel injection pump main body, 24 is a plunger barrel, 25 is a plunger, and 26 is a discharge. The valve 27 is an equal pressure valve. The discharge valve 26 of the fuel injection pump main body 23 and the fuel inlet fitting 4 are connected by an injection pipe. 28 is a water tank, 29 is a water supply pump, 30 is a water supply pipe, 31 is a water injection solenoid valve, and 32 is a water injection pipe connected to the water injection fitting 13. A controller 33 controls the valve opening timing and the valve opening period of the electromagnetic valve 31 and operates in synchronization with a crankshaft of an engine (not shown).

Next, the operation of the conventional example will be described.
The fuel supplied from the fuel tank 21 to the fuel injection pump 23 by the fuel supply pump 22 is highly compressed by the plunger 25 of the fuel injection pump, pushes up the discharge valve 26 and is sent to the fuel valve main body 1 from the injection pipe. This high pressure fuel
When the needle valve oil reservoir 8 is guided through the oil passage 5 in the fuel valve, the oil passage 6 in the presser foot and the oil passage 18 in the nozzle tip, the spring force of the spring 11 is overcome, and the needle valve 9 is pushed up. Fuel is injected.

In the water-injection diesel engine of the present invention, water is injected into the fuel oil passage at a time when the fuel valve 1 for fuel water injection is not injecting fuel, and the fuel is injected into the fuel tip remaining in the nozzle tip 2. Subsequently, the water is jetted. Next, a method of injecting water into the fuel valve will be described in detail. After the injection is completed, the pressure of the needle valve 9 and the oil reservoir 8 and the oil passage communicating therewith fluctuate to a residual pressure Pr determined by the equal pressure valve 27 of the fuel injection pump. The residual pressure Pr is lower than the valve opening pressure Pcc, which varies depending on the operation state, and does not match.

On the other hand, the water in the water tank 28 is
9, the pressure is increased to a pressure higher than the aforementioned residual pressure Pr. Next, when the water injection solenoid valve 31 is opened by the controller 33, high-pressure water pushes up the check valve 14 with the valve opening pressure Pp from the water injection pipe 32 to the water injection fitting 13 and the fuel valve water passage 16. , And is injected into the fuel oil passage through the junction passage 40. At this time, the pressure in the passage becomes the closing pressure Pcc of the equal pressure valve 27 because the injection is gentle. The amount of water to be injected is optimally controlled by the controller 33 by changing the opening time of the water injection solenoid valve 31. If the opening pressure of the equal pressure valve 27 is Pcc, the opening pressure of the check valve is Pp, and the opening pressure of the needle valve is Po, the following relationship is established among the three. Po>Pp> Pcc

When the plunger of the fuel injection pump rises and starts to compress the fuel, the fuel in the needle valve oil reservoir 8 and the fuel oil passage 18 in the nozzle tip is injected first, and then the fuel oil passage 6 in the presser foot and the fuel oil. The water flowing into the valve oil passage 5 is injected,
Finally, since the fuel is injected again, even if water is injected together with the fuel, there is no possibility that the combustion in the combustion chamber becomes unstable. FIG. 4 simultaneously shows changes in the pressure in the water passage and the pressure in the oil passage, the lift of the needle valve, and the movement of the solenoid valve for water injection. This indicates that the residual pressure remains in the water channel after the end of the water injection.

[0008]

As described above, when the fuel injection is completed, there is a pressure difference between the pressure in the oil passage and the pressure in the water passage, and when the valve opening pressure of the check valve 14 is lower than the above-mentioned pressure difference. The check valve 14 opens and water flows into the oil passage. This phenomenon is particularly pronounced when pressure fluctuations occur immediately after injection. When a large pressure drop occurs in the inflow water portion, a cavity is formed, and when the cavity is crushed by a high pressure thereafter, severe cavitation erosion may occur, and measures for securing reliability of parts are necessary. Become. SUMMARY OF THE INVENTION It is an object of the present invention to provide a water injection device which solves the above-mentioned problems of the conventional device and does not cause corrosion due to cavitation erosion in a fuel oil passage and a water passage downstream of a check valve.

[0009]

According to the present invention, there is provided a water injection device comprising:
In the water injection device for injecting fuel and water with the individual fuel valves, the water injection device is provided downstream of the water injection solenoid valve 31 and upstream of the check valve 14, and is opened before the fuel injection after the water injection is completed. It is characterized by having a solenoid valve 34 for draining water.

[0010]

In this apparatus, a water draining solenoid valve is provided between the water injection solenoid valve 31 and the check valve. Therefore, by opening the water draining electromagnetic valve between the end of water injection by the water injection electromagnetic valve 31 and the start of discharge of the fuel pump,
The residual pressure in the water passage between the water injection solenoid valve 31 and the check valve 14 can be reduced. As a result, even if the pressure in the oil passage downstream of the check valve 14 decreases immediately after fuel injection or the like, water does not flow into the oil passage without opening the check valve 14, and the oil passage downstream of the check valve and No cavitation erosion will occur in the waterways.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is an operation state diagram of an embodiment of the present invention, and FIG. 2 is an operation state diagram of the embodiment. In the figure, 1 is a fuel valve main body, 2 is a nozzle tip, 3 is an injection hole, 4 is a fuel inlet fitting, 5 is a fuel oil passage in the fuel valve, 6 is a fuel oil passage in the presser foot, 8 is a needle valve oil reservoir, 9 Is a needle valve, 10 is a needle valve spring receiver, 11 is a spring, and 12 is a valve opening pressure adjusting hardware of the needle valve. 13 is a water injection metal, 14
Is a check valve, 15 is a check valve spring, 16 is a water passage in the fuel valve, 1
Reference numeral 7 denotes a water passage in the presser foot, and reference numeral 18 denotes a fuel oil passage in the nozzle tip. The fuel oil passage 6 in the presser foot and the water passage 17 in the presser foot are joined by a merging passage 40, and also communicates with the fuel oil passage 18 in the nozzle tip 2 via the check valve 14.

Reference numeral 21 denotes a fuel tank, 22 denotes a fuel supply pump, 23 denotes a fuel injection pump main body, 24 denotes a plunger barrel, 25 denotes a plunger, 26 denotes a discharge valve, 27 denotes a constant pressure valve,
28 is a water tank, 29 is a water supply pump, 30 is a water supply pipe, 31 is a solenoid valve for water injection, and 32 is a water injection pipe. The water injection pipe 32 branches into water pipes 321 and 322 between the water injection fitting 13 and the water injection solenoid valve 31. At the end of the water pipe 322, a water draining solenoid valve 34 is attached. The valve open periods of the water injection electromagnetic valve 31 and the water discharge electromagnetic valve 34 are controlled by the controller 33.

Next, the operation of this embodiment will be described. Discharge of fuel and injection of water from the fuel injection pump are performed in the same manner as in the conventional example. That is, the water injection solenoid valve 31 is opened and the fuel is injected into the fuel oil passage between the end of the discharge of the fuel injection pump and the start of the discharge of the next fuel injection pump. After the water injection electromagnetic valve 31 is closed, the water draining electromagnetic valve 34 is opened, and the residual pressure in the water injection pipe 32 is reduced before the fuel injection pump 23 discharges. FIG. 2 shows these operating conditions. It is clearly shown that when the water draining solenoid valve 34 is operated, the residual pressure of the water channel of the check valve 14 decreases as shown at point A. Therefore, even if the residual pressure in the fuel injection pipe and the fuel pipe in the fuel valve main body 23 is instantaneously reduced due to the pressure wave after the fuel injection is completed, water is not injected into the fuel oil pipe and the pipe becomes cavitational. There is no risk of erosion.

[0014]

Since the present invention is constructed as described above, by reducing the residual pressure of the water downstream of the check valve 14, the check valve 14 does not open at the time when the water is not injected, so that the check is not performed. The inner surfaces of the oil passage and the water passage downstream of the valve do not corrode due to cavitation erosion.

[Brief description of the drawings]

FIG. 1 is a diagram of a water injection device according to a first embodiment of the present invention.

FIG. 2 is an operation explanatory view of the embodiment.

FIG. 3 is a diagram corresponding to FIG. 1 of a conventional example.

FIG. 4 is a diagram corresponding to FIG. 2 of a conventional example.

[Explanation of symbols]

1 fuel valve body, 9 needle valve, 14 (water injection) check valve, 1
Reference numeral 6: water passage in fuel valve, 17: water passage in presser foot, 23: fuel injection pump main body, 25: plunger, 27: constant pressure valve, 3
DESCRIPTION OF SYMBOLS 1 ... Solenoid valve for water injection, 32 ... Water injection pipe, 34 ... Solenoid valve for water drainage

Claims (1)

(57) [Claims] 1. A water injection device for injecting fuel and water with a single fuel valve, wherein the water injection device is provided with a branch provided downstream of a water injection solenoid valve (31) and upstream of a check valve (14). Solenoid valve for draining (34) that opens after fuel injection and before fuel injection
A water injection device for a diesel engine comprising: