JP2002130070A - Fuel and water injection internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel and water injection internal combustion engine capable of controlling the water injection with high accuracy by a comparatively simple control method, reducing the cost of a device of a water injection controlling and operating unit, and further obtaining the sufficient NOx reduction effect by controlling an injection rate of the fuel injection and the water injection at the same time. SOLUTION: This fuel and water injection internal combustion engine wherein the high-pressure fuel from a fuel injection pump and the water supplied from a water feed pump are injected into a combustion chamber from one fuel injection valve, comprises a water filling valve mounted on a water passage connected to a high-pressure fuel passage and opened when the pressure in the high-pressure fuel passage is lower than the pressure in the water passage, a fuel returning passage branched from an intermediate part of the high-pressure fuel passage and connected to a fuel tank, and a solenoid valve for opening and closing the fuel returning passage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is configured to inject high-pressure fuel supplied from a fuel injection pump through a fuel passage and water supplied from a water pump into a combustion chamber from one fuel injection valve. Fuel / water injection internal combustion engine, in particular, a fuel / water injection system in which fuel injection rate control and water injection can be performed in parallel by two solenoid valves provided in a fuel passage and a fuel return passage.
The present invention relates to a water injection internal combustion engine.

[0002]

2. Description of the Related Art In a diesel engine, a fuel / water injection diesel engine in which fuel and water are injected from a fuel injection valve into a combustion chamber has been proposed as an effective technique for reducing nitrogen oxides (NOx). . One such technique is the invention of Japanese Patent No. 2772114 filed by the present applicant. FIG. 5 shows the configuration of the invention, in which 001 is a fuel injection pump, 3 is a fuel injection valve, 01 is a fuel tank, 02 is a fuel supply pump, 019 is a water tank, 018 is a water supply pump, and 016 is fuel. A control valve 020 controls the supply of water to the injection valve 3, and a control device 020 controls opening and closing of the control valve 016.

In this fuel / water injection diesel engine, water pumped from a water tank 019 by a water supply pump 018 is sent to the control valve 016 through a water supply pipe 017. During the fuel discharge suspension period of the fuel injection pump 001, the control valve 0 is controlled via the control device 020.
The valve 16 is opened to feed a predetermined amount of water into the water passage 021 of the fuel injection valve 3 via the supply pipe 015. At this time,
The valve opening pressure Pr of the check valve 07 of the fuel injection pump 001 and the valve opening pressure P of the check valve 013 inside the fuel valve of the water passage 21
p, when the opening pressure _{P 0} of the needle valve 011 of the fuel injection valve _3, P 0> _Pr, P 0> Pp and because it is set, the water supplied to the water channel 021 in the fuel injection valve 3 Flows into the fuel passage 022 through the water passage 030 and the fuel / water junction portion 031 via the fuel valve check valve 013.

[0004] The fuel located on the fuel injection pump 001 side of the converging portion 031 in the fuel passage 022 is pushed back toward the fuel injection pump 001 through the high-pressure fuel pipe 08. As a result, the fuel injection valve 3 is filled with the oil reservoir 012 and the fuel corresponding to the volume from the oil reservoir 012 to the junction 031, and the fuel passage 022 on the upstream side of the junction 031.
Is filled with a predetermined amount of water, and the upstream side thereof is again in a layered state filled with fuel.

Next, the discharge of the fuel injection pump 001 is started, the fuel in the fuel injection valve 3 is compressed, and the pressure rises and becomes equal to or higher than the valve opening pressure P ₀ of the fuel injection valve 3.
The needle valve 011 is opened and injection is started. In the injection, among the fuel and water in the stratified state as described above, the fuel is first injected, and after the ignition delay period, the combustion is started. Subsequently, water is injected at the preceding fuel spray flame during combustion. The water injected at this time also becomes a spray and takes in the air in the combustion chamber into the inside thereof, so that air is supplied to the fuel previously injected, and combustion is activated.
Finally, the remaining fuel is injected into the preceding water spray and burns. Due to the thermal effect of the fuel and water injection, the temperature rise of the flame is suppressed, and the generation of NOx is suppressed.

[0006]

In the invention of Japanese Patent No. 2772114 shown in FIG. 5, after fuel and water are filled into the fuel injection valve 3 in layers, the fuel is injected into the combustion chamber by high-pressure fuel and injected. Due to the thermal effect of the fuel and water injection, the temperature rise of the flame is suppressed, and the generation of NOx is suppressed. However, in such a conventional technique, the amount of water injected into the fuel injection valve 3 is controlled by the control device 02.
Since the control is performed by changing the stroke and the valve opening timing of the control valve 016 according to 0, it is necessary to maintain the control accuracy of the control valve 016 high in order to obtain the required water injection amount and the water injection timing. With difficulty.

In the prior art, as described above, the control valve 016 is controlled with high control accuracy, and since only water flows through the control valve 016, rust is generated. To induce malfunction of the valve. Further, in the prior art, the technical gist is mainly the control of the water injection, and the control of the injection rate of the fuel injection, which has a large effect on the suppression of the generation amount of NOx, is not substantially performed. NOx reduction by water injection has not shown a sufficient effect. And the like.

The present invention has been made in view of the problems of the prior art,
Highly accurate water injection control can be performed with a relatively simple control method, and the equipment cost of water injection control and operation equipment is reduced.Furthermore, the fuel injection rate control and the water injection function are reduced. It is an object of the present invention to provide a fuel / water-injection internal combustion engine capable of achieving a sufficient NOx reduction effect by allowing the fuel cell and the fuel cell to be operated in parallel without causing a problem.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a fuel supply system comprising: a high-pressure fuel supplied from a fuel injection pump through a high-pressure fuel passage; In a fuel / water injection internal combustion engine configured to inject water supplied through a single fuel injection valve into a combustion chamber, the water passage is connected to the high-pressure fuel passage and provided in the water passage. A water injection valve that is opened when the pressure in the high-pressure fuel passage is lower than the pressure in the water passage, and a fuel return passage that is branched from the middle of the high-pressure fuel passage and connected to the fuel tank. And a first on-off valve provided in the fuel return passage for opening and closing the return passage.

In the first aspect of the present invention, preferably, as in the eighth aspect, a passage area of the fuel return passage is provided between a branch portion of the fuel return passage and the high pressure fuel passage and the first on-off valve. An aperture mechanism is installed to reduce the size.

According to a second aspect of the present invention, in the first aspect, the first on-off valve opens the fuel return passage during a predetermined period between the fuel injection from the fuel injection valve and the next fuel injection. Allowing the high pressure fuel passage to communicate with the fuel return passage,
The water injection valve is configured to be opened by a decrease in pressure of the high-pressure fuel passage due to communication between the high-pressure fuel passage and a fuel return passage so that water can be supplied from the water passage into the fuel injection valve. I do.

According to a third aspect of the present invention, in the first aspect, a second opening / closing valve provided in a fuel supply passage connecting the fuel tank and the fuel inlet of the fuel injection pump to open and close the fuel supply passage is provided. And wherein the second on-off valve closes the fuel supply passage and discharges high-pressure fuel from the fuel injection pump to the fuel injection valve when the first on-off valve closes the fuel return passage. It is characterized by being done.

According to a fourth aspect of the present invention, in the first aspect, a second opening / closing valve is provided in a fuel supply passage connecting the fuel tank and the fuel inlet of the fuel injection pump and opens and closes the fuel supply passage. And the first on-off valve is configured to open and close once during one cycle of the engine in association with the second on-off valve.

According to a fifth aspect of the present invention, in the third aspect, the second on-off valve is a normally open solenoid valve.
The first on-off valve is configured as a normally closed solenoid valve, and the first on-off valve is opened for a predetermined period earlier than the closing timing of the second on-off valve, and the second on-off valve is opened. The valve is closed during the valve closing period to form a fuel injection pressure rise stagnation period at the beginning of fuel injection.

The invention according to claim 6 is the invention according to claim 3 or 4.
, Wherein both the first on-off valve and the second on-off valve are configured as normally open solenoid valves. In claim 6, preferably, as in claim 7, an opening / closing means for opening / closing the fuel return passage is provided in the fuel return passage upstream or downstream of the first opening / closing valve.

According to a ninth aspect of the present invention, there is provided a specific configuration of a fuel injection pump. In the first aspect, the fuel injection pump opens a valve by the pressure of a plunger chamber to inject the fuel in the plunger chamber into the fuel. A fuel discharge valve to be delivered to a valve; and a fuel check valve provided in a return passage which bypasses the plunger chamber and the fuel passage and bypassing the fuel discharge valve and allowing only a flow from the fuel passage to the plunger chamber. It is characterized by comprising.

According to this invention, the fuel return passage is opened by the first on-off valve during a period in which the second on-off valve is open, that is, a predetermined period between the fuel injection from the fuel injection valve and the next fuel injection. By opening the fuel passage side including the high-pressure fuel passage to communicate with the fuel return passage and releasing the pressure on the fuel passage side to an atmospheric pressure lower than the opening pressure of the water injection valve, the water injection valve is opened to open the water injection valve. Water can be supplied to the fuel passage side. That is, during the injection suspension period between the fuel injection in which the second on-off valve is opened and the next fuel injection, the first
The water injection is controlled by a very simple means and a simple device of opening the on-off valve of the above, and the generation of NOx can be suppressed.

Further, according to the fifth aspect of the present invention, the second
By opening the first opening / closing valve a predetermined period earlier than the closing timing of the opening / closing valve and returning a part of the fuel to the fuel tank side, the fuel injection amount per unit time at the initial stage of the fuel injection, that is, the injection amount The rate of increase in the fuel injection pressure is reduced, so that a fuel injection pressure increase stagnation period is formed, and the fuel injection pressure increase rate becomes gentle. Thereby, the combustion speed in the combustion chamber becomes slow, and the generation of NOx is suppressed. By changing the preceding opening time of the solenoid valve with respect to the closing timing of the fuel solenoid valve, the degree of increase in the fuel injection rate can be easily adjusted.

Further, according to the fourth aspect, the first aspect is provided.
The fuel injection rate is controlled by opening and closing the on-off valve once in one cycle of the engine in association with the second on-off valve, and the first on-off valve is opened and closed within a predetermined period of the fuel injection suspension period. Water injection control by opening the valve to reduce the pressure in the high-pressure fuel pipe and opening the water injection valve can also be performed.

According to a sixth aspect of the present invention, both the first on-off valve and the second on-off valve are configured as normally open solenoid valves, so that the first on-off valve and the second on-off valve can be used. The two on-off valves can be used as a common product, which is excellent in interchangeability and reduces the cost of parts.

Further, according to the present invention, the first aspect is provided.
Since the opening / closing means for opening / closing the fuel return passage is provided on the upstream side or downstream side of the opening / closing valve of the above, when the closing period of the first opening / closing valve configured as the normally open type solenoid valve becomes long, By opening the first on-off valve without energizing it and closing the on-off valve, it is possible to prevent the first on-off valve from burning due to overheating.

Further, according to the present invention, by adjusting the throttle ratio of the throttle mechanism, that is, the minimum area of the fuel return passage toward the fuel tank side, and adjusting the fuel return amount, the fuel injection initial stage is improved. , The degree of increase in the fuel injection rate can be adjusted.

Therefore, according to the present invention, the control of the fuel and water injection from the fuel injection valve and the control of the degree of increase of the fuel injection rate are performed in a very simple and simple manner as compared with the prior art. You can do it. As a result, the engine performance can be maintained high and the generation of NOx can be suppressed.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to an embodiment shown in the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not merely intended to limit the scope of the present invention, but are merely illustrative examples unless otherwise specified. Absent.

FIG. 1 is a configuration diagram of a fuel / water injection system for a diesel engine according to an embodiment of the present invention, FIG. 2 is a sectional view showing the structure of a fuel injection pump and a fuel injection valve in the embodiment, and FIG. FIG. 4 is an operation explanatory view of the third embodiment, and FIG.

In FIG. 1, reference numeral 1 denotes a fuel injection pump whose main part is shown in detail in FIG. 2, which is reciprocated by a fuel cam 20 provided on a cam shaft which rotates in conjunction with a crankshaft of an engine. The fuel in the plunger chamber 27 is pressure-fed by the plunger 25. 3
Is a fuel injection valve the details of which are shown in FIG. 1
Reference numeral 3 denotes a fuel tank, 31 denotes a fuel supply pipe connecting the fuel tank 13 and a fuel inlet of the fuel injection pump 1, and 12 denotes a fuel supply pipe which is provided in the fuel supply pipe 31 and transfers fuel in the fuel tank 13 to the fuel injection pump 1. It is a fuel supply pump for feeding.

Reference numeral 2 denotes a high-pressure fuel pipe connecting the high-pressure fuel outlet of the fuel injection pump 1 and a fuel passage 022 of the fuel injection valve 3 (see FIG. 2). Reference numeral 7 denotes a fuel return pipe branched off from the middle of the high-pressure fuel pipe 2 and connected to the fuel tank 13. Reference numeral 11 denotes a water tank, 34 denotes a water supply pipe connecting the water tank 11 to a water passage 021 (see FIG. 2) of the fuel injection valve 3, and 10 denotes a water supply pipe provided in the water supply pipe 34. This is a water pump that supplies water to the fuel injection valve 3. Reference numeral 9 denotes a water injection valve provided in a water passage 21 of the fuel injection valve 3 communicating with the outlet side of the water supply pipe 34, and is directed from the water passage 21 to the fuel passage 022 and the merging portion 031. Only the flow is allowed, and the valve opening pressure Pp is configured to be smaller than the valve opening pressure P _{0 of the} needle valve 011, and the fuel passage 022 side in the fuel injection valve 3 communicated with the high pressure fuel pipe 2. Pressure of the water passage 021
The valve is opened when the pressure falls below the internal pressure.

Reference numeral 4 denotes a main solenoid valve (second on-off valve) provided on the fuel supply pipe 31 for opening and closing the fuel supply pipe. The main solenoid valve 4 is a normally open solenoid valve which is always opened and closed when energized. Reference numeral 5 denotes a sub solenoid valve (first on-off valve) provided on the fuel return pipe 7 to open and close the fuel return pipe. The auxiliary solenoid valve 5 is a normally closed solenoid valve which is normally closed and opened when energized. Therefore, the main solenoid valve 4 is connected to the fuel supply line 31.
Is closed, and when the sub solenoid valve 5 closes the fuel return line 7, the plunger 25 in the fuel injection pump 1 pressurizes the fuel in the plunger chamber 27 to a high pressure and sends it to the fuel injection valve 3. It will be.

In FIG. 2 showing details of the fuel injection pump 1 and the fuel injection valve 3, reference numeral 1 denotes a fuel injection pump which is constructed as follows. Reference numeral 25 denotes a plunger which is slidably fitted on the inner periphery of the plunger barrel 24 and is reciprocated by the fuel cam 20. Reference numeral 27 denotes a plunger chamber.
Reference numeral 7 denotes a fuel discharge valve, and reference numeral 18 denotes a fuel check valve. 027 is a spacer fixed on the upper part of the plunger barrel 24,
Reference numeral 22 denotes an oil supply hole formed in the spacer 027, which is connected to the fuel supply pipe 31. As a result, the fuel in the plunger chamber 27 is pressurized to a high pressure by the upward movement of the plunger 25, and the high-pressure fuel is pushed to open the fuel discharge valve 17 and discharged to the high-pressure fuel pipe 2. Assuming that the valve opening pressure Pr of the fuel check valve 18, the valve opening pressure Pp of the water injection valve 9, and the valve opening pressure P ₀ of the needle valve 011 of the fuel injection valve 3, the relationship is P ₀ > Pr. , P ₀ > Pp, and Pr> Pp. Such a fuel injection pump 1 is
This is a known jerk type fuel injection pump in which an injection amount control lead of a plunger 25 and an injection amount adjusting mechanism such as a fuel adjustment rack and a pinion are removed.

In FIG. 2 showing the details of the fuel injection valve 3, reference numeral 09 denotes a main body, 033 denotes a nozzle tip, 010 denotes a plurality of injection holes drilled at the tip of the nozzle tip 033,
1 is a needle valve fitted in the nozzle tip 033 so as to be able to reciprocately slide, 014 is a needle valve spring for setting the valve opening pressure P ₀ of the needle valve 011, and 012 faces the tip of the needle valve 011. This is the oil reservoir. A fuel passage 022 has an inlet end connected to the high-pressure fuel pipe 2 and an outlet end connected to the oil reservoir 012. Reference numeral 021 denotes a water passage whose inlet end is connected to the water supply pipe 34 and whose outlet end is connected to a horizontal water passage 030 formed below the nozzle tip 033. The outlet end of the horizontal water passage 030 is connected to the fuel passage 02.
The lower part 2 is joined to a portion upstream of the oil reservoir 012 to form a junction part 031. The basic structure of the fuel injection valve 3 described above is disclosed in Japanese Patent No. 277211 shown in FIG.
This is the same as the fuel injection valve in the invention of No. 4.

The operation of the diesel engine provided with the fuel / water injection system having the above configuration will be described with reference to FIG. First, at the time of normal injection by the main solenoid valve 4 shown in FIG. 3A, the main solenoid valve 4 configured as a normally open solenoid valve is energized to close the fuel supply pipe 31, and the normally closed type solenoid valve is closed. The auxiliary solenoid valve 5 constituted by the solenoid valve is kept closed without energizing. In this state, when the plunger 25 which is reciprocated by the fuel cam 20 of the fuel injection pump 1 is moved upward, the high-pressure fuel pipe 2 is a closed space. pressurized in opening pressure _{P 0} or more high pressure 011.

Thus, the fuel in the plunger chamber 27 pushes the fuel discharge valve 17 open, reaches the oil reservoir 012 from the high-pressure fuel pipe 2 through the fuel passage 022 of the fuel injection valve 3, and acts on the needle valve 011. The valve is opened to be injected into the combustion chamber. Then, if the main solenoid valve 4 is de-energized,
The pressure in the plunger chamber 27 becomes the supply hydraulic pressure, and the fuel injection ends. The fuel injection timing at the time of the normal injection, that is, the fuel injection start timing and the fuel injection end timing are adjusted by the opening / closing timing of the main solenoid valve 4, and the fuel injection amount is adjusted while the main solenoid valve 4 is closed and the fuel cam 20. Adjust by the lift (cam profile).

Next, when adjusting the injection rate at the beginning of fuel injection by opening and closing the sub solenoid valve 5, FIG.
As shown in (B), the main solenoid valve 4 constituted as a normally open solenoid valve is energized and the fuel supply line 31 is turned on.
Is energized to the auxiliary solenoid valve 5 configured as a normally closed solenoid valve earlier by a preset fixed time Δ than the timing of closing the fuel return line 7 by the auxiliary solenoid valve 5.
And the sub solenoid valve 5 is closed before the time when the main solenoid valve 4 is opened and fuel injection ends as described above. According to this operation, before the fuel supply line 31 is closed by the main electromagnetic valve 4 and the fuel pressure starts to rise, the fuel return line 7 to the fuel tank 13 is opened by the auxiliary electromagnetic valve 5. Therefore, the pressure in the high-pressure fuel pipe 2 is released to the fuel return pipe 7 via the throttle mechanism 6, and a part of the fuel pressurized by the plunger 25 of the fuel injection pump 1 passes through the throttle mechanism 6. To return to the fuel return pipe 7 side.

By opening the sub solenoid valve 5 and returning a part of the fuel to the fuel tank 13, the fuel injection amount per unit time at the beginning of the fuel injection, that is, the degree of increase in the injection rate is reduced. , Fuel injection pressure rise stagnation period (Fig. 3
(P1 part of (B)) is formed, and the rate of increase of the fuel injection pressure becomes gentle. Thereby, the combustion speed in the combustion chamber becomes slow, and the generation of NOx is suppressed. And
By changing the preceding opening time Δ of the sub solenoid valve 5 with respect to the closing timing of the main solenoid valve 4, the degree of increase of the fuel injection rate can be easily adjusted. Further, by adjusting the throttle ratio of the throttle mechanism 6, that is, the minimum area of the fuel return passage toward the fuel return pipe 7, and adjusting the fuel return amount, the degree of increase in the fuel injection rate at the beginning of fuel injection can be adjusted. Becomes possible.

Next, when water is injected together with fuel from the fuel injection valve 3 by opening and closing the main solenoid valve 4 and the sub solenoid valve 5, as shown in FIG. The fuel supply line 31 is closed by energizing the solenoid valve 4 and a normally closed sub solenoid valve 5 is provided.
The fuel injection is also performed in the closed state, and after the fuel injection is terminated by the de-energization of the main solenoid valve 4, the high-pressure fuel pipe 2
The pressure in the fuel passage including the inside decreases to about the valve opening pressure Pr of the fuel check valve 18 of the fuel injection pump 1. In such a pressure state, the sub solenoid valve 5 is energized within a predetermined period (between t _{1 and} t ₂ ) in the fuel injection suspension period until the fuel injection of the next cycle, and the fuel return line 7 is connected. open. Thereby, the pressure in the high-pressure fuel pipe 2 is released to the pressure (atmospheric pressure) on the side of the fuel return pipe 7 and the fuel tank 13, and the fuel passage 022 in the fuel injection valve 3 communicated with the high-pressure fuel pipe 2. Side pressure is lower than the pressure in the water passage 021 pressurized by the water pump 10, and the water injection valve 9 is opened.

At this time, assuming that the valve opening pressure Pr of the fuel check valve 18, the valve opening pressure Pp of the water injection valve 9, and the valve opening pressure P ₀ of the needle valve 011 of the fuel injection valve 3, these relations are as follows. Since P ₀ > Pr, P ₀ > Pp, and Pr> Pp, the water supplied to the water passage 21 of the fuel injection valve 3 passes through the water injection valve 9 to the water passage 030 and the fuel. Fuel passage 0 passing through water confluence 031
It flows into 22.

The fuel located on the fuel injection pump 1 side of the merging portion 031 in the fuel passage 022 is
Is pushed back through the high-pressure fuel pipe 2 in the direction of. As a result, the fuel injection valve 3 is filled with the oil reservoir 012 and the fuel corresponding to the volume from the oil reservoir 012 to the junction 031, and the fuel passage 022 on the upstream side of the junction 031 is filled with a predetermined amount. Is filled with water, and further upstream is in a layered state with fuel again.

Next, when the discharge of the fuel injection pump 1 is started, the fuel in the fuel injection valve 3 is compressed, and the pressure rises and becomes equal to or higher than the valve opening pressure P ₀ of the fuel injection valve 3, the needle valve 011. Is opened and injection is started. In the injection, among the fuel and water in the stratified state as described above, the fuel is first injected, and after the ignition delay period, the combustion is started. Subsequently, water is injected at the preceding fuel spray flame during combustion. The water injected at this time also becomes a spray and takes in the air in the combustion chamber into the inside thereof, so that air is supplied to the fuel previously injected, and combustion is activated. Finally, the remaining fuel is injected into the preceding water spray and burns. Due to the thermal effect of the fuel and water injection, the temperature rise of the flame is suppressed, and the generation of NOx is suppressed.

As described above, during the predetermined period between the fuel injection from the fuel injection valve 3 and the next fuel injection, the fuel return pipe line 7 is opened by the sub solenoid valve 5 and the fuel passage including the high-pressure fuel pipe 2 is provided. Side of the fuel return pipe 7 and the pressure on the fuel passage side is released to an atmospheric pressure lower than the opening pressure of the water injection valve 9, thereby opening the water injection valve 9 and opening the fuel passage side. Can be supplied with water. That is, the water injection can be controlled by a very simple means and a simple device in which the auxiliary solenoid valve 5 is opened during a predetermined period in the injection suspension period between the fuel injection and the next fuel injection. .

Next, in a second embodiment of the present invention, FIG.
In the embodiment shown in FIG. 1 (first embodiment), the auxiliary solenoid valve (first on-off valve) 5 composed of a normally closed solenoid valve is
It is configured to open and close once during a cycle. That is,
In such an embodiment, as shown in FIG. 3 (d), the secondary electromagnetic valve 5 t ₃ to -t ₄ period off during one cycle. According to this embodiment, the closing timing of the main solenoid valve 4 which controls the start of fuel injection and the closing timing of the sub solenoid valve 5 (t
By combining _fourth timing) and controls the injection rate of fuel, the similar to the case shown in FIG. 3 (C) in the first embodiment, during a predetermined time period (t ₃ -t ₄ in the fuel injection stop period By opening the sub-electromagnetic valve 5 to reduce the pressure in the high-pressure fuel pipe 2 and opening the water injection valve 9, the injection of water can also be controlled. Other configurations are the same as in the first embodiment.

Next, in a third embodiment of the present invention, FIG.
In the embodiment shown in FIG. 1 (first embodiment), the fuel return line 7
Is configured as a normally open solenoid valve. In this embodiment, as shown in FIG. 3 (e), the sub solenoid valve 5 which is always open is configured to close by energization. In FIG. 3E, T is an energization period, that is, a valve closing period. Other configurations are the same as in the first embodiment. In this embodiment, the sub solenoid valve 5 is a normally open type solenoid valve similar to the main solenoid valve 4, so that the main solenoid valve 4 and the sub solenoid valve 5 can be used as a common product. And the cost of parts is reduced.

In the third embodiment, since the auxiliary solenoid valve 5 is a normally open solenoid valve,
During the period in which the fuel injection rate control and the water injection control are not performed, it is necessary to continuously energize the sub solenoid valve 5 and close it. If the energization period is lengthened, the solenoid valve coil of the sub solenoid valve 5 may be burned. However, in the third embodiment, as shown in FIG. 4, the fuel return pipe 7 is opened and closed at a downstream portion (or an upstream portion) of the sub solenoid valve 5. An on-off valve is provided. With this configuration, when the valve closing period of the sub solenoid valve 5 becomes long as described above, the sub solenoid valve 5 is opened without being energized, and the on / off valve 40 is closed. Thus, the occurrence of burnout due to overheating of the sub solenoid valve 5 can be prevented. The auxiliary solenoid valve 5 is not limited to the on-off valve 40.
Any means can be used as long as it can close the fuel return pipe 7 without energizing the coil.

[0043]

As described above, according to the present invention, the solenoid valve is opened for a predetermined period in the injection suspension period between the fuel injection and the next fuel injection to adjust the pressure on the fuel passage side to the opening pressure of the water injection valve. By opening the water injection valve to supply water to the fuel passage side by opening the water injection valve by lowering the atmospheric pressure to a lower level, the water injection is controlled by a very simple means and a simple device, and NOx is reduced. Generation can be suppressed.

According to the fifth aspect of the invention, by opening the solenoid valve and returning a part of the fuel to the fuel tank side, the fuel injection amount per unit time at the initial stage of the fuel injection, that is, the injection amount The rate of increase in the fuel injection pressure is reduced, so that a fuel injection pressure increase stagnation period is formed, and the fuel injection pressure increase rate becomes gentle. Thereby, the combustion speed in the combustion chamber becomes slow, and the generation of NOx is suppressed. By changing the preceding opening time of the solenoid valve with respect to the closing timing of the fuel solenoid valve, the degree of increase in the fuel injection rate can be easily adjusted. Further, according to the present invention, by controlling the fuel injection rate by opening and closing the first on-off valve once in one cycle of the engine in association with the second on-off valve, During the predetermined period of the fuel injection suspension period, the first on-off valve is opened to lower the pressure in the high-pressure fuel pipe, and the water injection valve is opened to control the water injection.

According to a sixth aspect of the present invention, both the first on-off valve and the second on-off valve are configured as normally open solenoid valves, so that the first on-off valve and the second on-off valve can be used. The two on-off valves can be used as a common product, which is excellent in interchangeability and reduces the cost of parts.

Further, according to the seventh aspect of the present invention, the first
Since the opening / closing means for opening / closing the fuel return passage is provided on the upstream side or downstream side of the opening / closing valve of the above, when the closing period of the first opening / closing valve configured as the normally open type solenoid valve becomes long, By opening the first on-off valve without energizing it and closing the on-off valve, it is possible to prevent the first on-off valve from burning due to overheating.

Further, according to the present invention, the degree of increase in the fuel injection rate at the beginning of fuel injection can be adjusted by adjusting the throttle rate of the throttle mechanism and adjusting the fuel return amount.

In short, according to the present invention, the fuel injection pump having a simple structure and the first and second on-off valves are combined to control the on-off control of the two on-off valves. The control of the fuel and water injection from the fuel injection valve and the control of the degree of increase of the fuel injection rate can be performed in parallel with a simple and simple method. This allows
It is possible to provide a fuel / water injection internal combustion engine capable of maintaining high engine performance and suppressing generation of NOx.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a fuel / water injection system of a diesel engine according to first to third embodiments of the present invention.

FIG. 2 is a sectional view showing a structure of a fuel injection pump and a fuel injection valve in the embodiment.

FIG. 3 is an operation explanatory view in the embodiment.

FIG. 4 is a configuration diagram near an on-off valve according to a third embodiment.

FIG. 5 is a main part configuration diagram showing a conventional technique.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 fuel injection pump 2 high-pressure fuel pipe 3 fuel injection valve 4 main solenoid valve 5 auxiliary solenoid valve 6 throttle mechanism 7 fuel return pipe 9 water injection valve 10 water pump 010 injection hole 11 water tank 011 needle valve 12 fuel supply pump 012 oil reservoir DESCRIPTION OF SYMBOLS 13 Fuel tank 17 Fuel discharge valve 18 Fuel check valve 20 Fuel cam 22 Filling hole 021 Water passage 022 Fuel passage 24 Plunger barrel 25 Plunger 27 Plunger chamber 31 Fuel supply pipe 031 Merging section 34 Water supply pipe 40 Open / close valve

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02M 37/00 331 F02M 37/00 341H 341 55/00 D 55/00 B 55/02 350P 55/02 350 350U 59/44 K 59/44 63/00 C 63/00 25/02 A (72) Inventor Yoshinori Nagae 5-717-1, Fukahoricho, Nagasaki-shi Nagasaki Research Laboratory, Mitsubishi Heavy Industries, Ltd. (72) Inventor Kenichi Iwanaga 5-717-1 Fukahori-cho, Nagasaki-shi Mitsubishi Heavy Industries, Ltd.Nagasaki Research Laboratory (72) Inventor Akira Numata 3000 Tana, Sagamihara-shi, Kanagawa Prefecture ) Inventor Takeshi Arai 12 Nishikicho, Naka-ku, Yokohama-shi F-term in Mitsubishi Heavy Industries, Ltd. Yokohama Works 3G023 AA05 AB05 AC08 3G066 AA07 AB02 AB08 AD12 BA25 BA33 BA61 CA04T CA08 CA09 CA 22T CB07U CB16 CC06T CC14 CE13 CE22 DA08 DA11 DA13

Claims (9)

[Claims] The fuel injection pump is configured to inject high-pressure fuel supplied from a fuel injection pump through a high-pressure fuel passage and water supplied from a water pump through a water passage from one fuel injection valve into a combustion chamber. In the fuel / water injection internal combustion engine, the water passage is connected to the high-pressure fuel passage, and is opened when the pressure in the high-pressure fuel passage provided in the water passage falls below the pressure in the water passage. A water injection valve to be valved, a fuel return passage branched from the middle of the high pressure fuel passage and connected to the fuel tank, and a first opening / closing valve provided in the fuel return passage to open and close the return passage. A fuel / water injection internal combustion engine, comprising: 2. The first on-off valve opens the fuel return passage during a predetermined period between fuel injection from a fuel injection valve and the next fuel injection, and communicates the high-pressure fuel passage with the fuel return passage. In other words, the water injection valve is configured to be opened by a decrease in the pressure of the high-pressure fuel passage due to the communication between the high-pressure fuel passage and the fuel return passage so that water can be supplied from the water passage into the fuel injection valve. The fuel / water injection internal combustion engine according to claim 1, wherein: 3. A fuel supply system, comprising: a second opening / closing valve provided in a fuel supply passage connecting a fuel tank and a fuel inlet of the fuel injection pump, for opening and closing the fuel supply passage. 2. The fuel injection pump according to claim 1, wherein a high pressure fuel is discharged from the fuel injection pump to the fuel injection valve when the supply passage is closed and the first on-off valve closes the fuel return passage. A fuel-water injection internal combustion engine as described. 4. A fuel supply system, comprising: a second on-off valve provided in a fuel supply passage connecting a fuel tank and a fuel inlet of the fuel injection pump for opening and closing the fuel supply passage. 2. The fuel / water injection internal combustion engine according to claim 1, wherein the internal combustion engine is configured to open and close once during one cycle of the engine in association with the second on-off valve. 5. The valve according to claim 1, wherein the second on-off valve is a normally open solenoid valve, and the first on-off valve is a normally closed solenoid valve. The valve is configured to be opened a predetermined period earlier than the valve closing timing, and to be closed during the valve closing period of the second on-off valve, thereby forming a fuel injection pressure rise stagnation period at the beginning of fuel injection. 4. The fuel according to claim 3, wherein
Water injection internal combustion engine. 6. The fuel / water injection internal combustion engine according to claim 3, wherein both the first on-off valve and the second on-off valve are configured as normally open solenoid valves. 7. The fuel supply according to claim 6, wherein an opening / closing means for opening / closing the fuel return passage is provided upstream or downstream of the first opening / closing valve in the fuel return passage. Water injection internal combustion engine. 8. A throttle mechanism for reducing a passage area of the fuel return passage is provided between a branch of the fuel return passage from the high pressure fuel passage and the first on-off valve. The fuel / water injection internal combustion engine according to claim 1, wherein 9. The fuel injection pump opens a valve by the pressure of a plunger chamber and sends the fuel in the plunger chamber to the fuel injection valve, and connects the fuel discharge pump to the plunger chamber and the fuel passage. 2. A fuel / water injection internal combustion engine according to claim 1, further comprising a fuel check valve provided in a return passage which bypasses the valve and allowing only a flow from the fuel passage toward the plunger chamber.