JP2002221101A - Fuel emulsifying device using light fuel as fuel for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more idealistically emulsify a diesel fuel and avoid a bad influence of water separation at the time of stopping a diesel engine, as to the improvement of the diesel engine of a fuel supply type. SOLUTION: In an emulsifying device 15 for fuel to the diesel engine, a fuel emulsifying means is equipped with a series of mutually meshed gears 24, 26, and 28 eccentrically disposed relative to the circumference of a housing 16, and a circumferential gap the interval of which changes in the direction of the circumference is formed between the mutually eccentric gears 24, 26, and 28 and the inner periphery of the housing in order to structure a fuel emulsifying passage. The flow of fluid in the passage is formed into two layers of flow having opposite directions, one running along the outer periphery of the gears and another running along the inner periphery of the housing because there is a part where the gap of the fuel emulsifying passage is narrow, water drops are crushed by the collision of the two layers of the flow, high emulsification is achieved, and the flow is injected from a fuel injection valve 9 through a fuel injection pump 10. Before stopping the engine, the fuel emulsifying means is made inoperative, and an operation is continued for a while with a water-free fuel supplied to the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a diesel engine for supplying emulsified fuel, which can significantly improve combustion efficiency as compared with a conventional system and can provide clean exhaust gas. is there.

[0002]

2. Description of the Related Art Various attempts have been made to emulsify diesel oil as a fuel by mixing it with added water as a technique for improving combustion in diesel engines. That is, it is intended to improve the combustion by emulsifying the fuel to make the fuel particles fine, and increasing the contact area with the air. That is, a large number of added water droplets are mixed into fuel oil droplets by emulsification, and the added water droplets thus mixed in the oil droplets explosively expand during combustion, and the oil droplets are extremely finely crushed and used for combustion. Since it diffuses while being in contact with air, almost gas-combustion-like combustion operation is expected, and it is intended to improve flammability.

[0003]

The emulsification using a surfactant is not suitable for diesel fuel because of the risk of generating harmful gases after combustion. For this reason, a method of subdividing water droplets by using a high-speed flow in a venturi or the like and a mixing chamber has been generally used. However, since the fragmentation effect of the particles is not sufficient in the conventional method,
Because the added water droplets are not sufficiently small in particle size, the desired effect of emulsion combustion cannot be obtained in many cases, and the emulsion combustion method has not been practically used in diesel engines.

[0004] The present invention has been made in view of the above problems, and since the diesel fuel can be emulsified more ideally, ideal combustion in a combustion chamber is realized.
The purpose is to achieve a dramatic reduction of harmful exhaust gas from diesel engines. It is another object of the present invention to prevent adverse effects on fuel system components due to separated water after engine stoppage regardless of water addition.

[0005]

According to the first aspect of the present invention, there is provided a fuel emulsifying means for emulsifying a fuel supplied to an internal combustion engine by adding water thereto, wherein the fuel emulsifying means comprises a housing and a fuel emulsifying means. , A plurality of gears meshed in series, each of which is arranged to face the circumferential surface of the housing, and rotation driving means for the gears. Circumferential gaps whose intervals vary in the direction are formed, and these circumferential gaps are connected in series to form a fuel emulsification passage. Fuel and added water are supplied to the emulsification passage from one end thereof, and the emulsified fuel is formed. Is taken out from the other end of the emulsification passage and supplied to the internal combustion engine.Furthermore, prior to the stop of the engine, the operation of the fuel emulsification means is invalidated, and the water-free fuel is supplied to the engine. Driving Fuel supply apparatus is provided for an internal combustion engine having a engine stop control means allowed to continue at.

The operation and effect of the first aspect of the present invention will be described. During the normal operation of the internal combustion engine, the emulsified fuel is supplied to the internal combustion engine by the operation of the fuel emulsifying means as described below. That is, the gears meshing in series are opposed to the corresponding inner peripheral surface of the housing, and a circumferential gap is formed between the inner circumference of the housing and the outer circumference of the gear, the interval of which varies along the circumferential direction. The circumferential gap is connected to form a fuel emulsification passage. Therefore, the free flow of the fuel + additive water introduced into the fuel emulsification passage in the narrowed portion of each circumferential gap is restricted, and as a result, the tooth surface of the rotating gear is confined in the circumferential gap. The flow in the direction of gear rotation (forward flow) and the flow in the opposite direction along the inner periphery of the stationary housing (reverse flow) coexist. Water having a large specific gravity is left in the forward flow along the tooth surface, but such large water droplets, when trying to fly outward due to the centrifugal force of the rotating gear, have a small diameter in the circumferential gap. The part is sheared by the accelerated reverse flow at the site and undergoes crushing action. Such a water droplet crushing action is repeated many times by backflow, and as a result, a high degree of atomization of water droplets is achieved, and one oil droplet having a diameter of about 30 to 130 microns is about 1 to 5 microns. A high degree of emulsified fuel into which several hundred water droplets having the same diameter are mixed can be obtained. The highly atomized emulsified fuel is injected into the combustion chamber from the fuel injection valve via the fuel injection pump. Therefore, the present invention can significantly improve the combustion efficiency.

Further, the engine stop time control means invalidates the operation of the fuel emulsification means prior to the stop of the engine. That is, prior to the actual stoppage of the diesel engine, the operation without adding water to the fuel is continued for a while, and the emulsified fuel remaining in the fuel injection system is completely replaced by the normal fuel. Since the gas does not remain in the fuel injection system, there is an effect that it is possible to completely eliminate the adverse effect that may occur in the fuel injection system due to the separation of water that occurs within a relatively short time after the internal combustion engine is stopped.

According to the invention described in claim 2, according to claim 1
The invention provides a fuel supply device for an internal combustion engine, characterized in that the engine stop-time control means automatically switches between emulsified fuel supply and water-free fuel supply by the emulsified fuel discharge pressure itself. .

The operation and effect of the second aspect of the present invention will be described. During normal operation, the emulsified fuel is supplied to the internal combustion engine because the discharge pressure of the emulsified fuel is high, and when the engine is stopped, the discharge pressure of the emulsified fuel is reduced. Automatic switching to fuel supply is performed. Therefore, there is no need to install a switching valve or the like, which is advantageous in cost.

[0010] According to the third aspect of the present invention, the first aspect is provided.
In the invention described in (1), there is provided a fuel emulsification device for an internal combustion engine, wherein the internal combustion engine is a diesel engine.

The operation and effect of the third aspect of the invention will be described. Since highly emulsified emulsified fuel is supplied to a diesel engine, complete combustion can be performed in a combustion chamber. It is possible to purify exhaust gas, which is an urgent issue, and in particular, to reduce particulates in diesel engine exhaust gas.

According to the invention described in claim 4, according to claim 1,
In the invention described in 5, the gear is arranged vertically,
A fuel emulsification device for an internal combustion engine is provided, wherein the supply side is located below the discharge side.

[0013] The operation and effect of the invention of claim 4 will be described. By arranging a series of gears vertically and positioning the supply side downward, even if the emulsified fuel is separated when the internal combustion engine is stopped, The heavy water is concentrated on the lower side of the relationship of the specific gravity, but is emulsified again by the rotation of the gear at the next start, and can be supplied to the internal combustion engine.

According to the invention described in claim 5, according to claim 4,
The present invention provides a fuel emulsification apparatus for an internal combustion engine, wherein a forced drainage means for drain water is provided at the bottom of the housing.

According to the fifth aspect of the present invention, it is unavoidable that water is deposited on the bottom of the housing due to the separation of water and oil when the engine is stopped, but the drain water is forcibly discharged by drain means. Water can be efficiently discharged.

According to the invention of claim 6, according to claim 1,
In the invention described in (1), there is provided a fuel emulsification apparatus for an internal combustion engine, comprising an electric pump for controlling water addition following a change in fuel flow rate.

The operation and effect of the sixth aspect of the present invention will be described. Since the electric pump controls the water additive following the flow rate of the fuel, it follows the change in the fuel flow rate due to the operating conditions of the internal combustion engine. The optimum amount of water can always be added.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 8 denotes a diesel engine main body, 9 denotes a fuel injection valve for injecting fuel into each combustion chamber of the engine main body, 10 denotes a well-known row type fuel injection pump,
Low pressure fuel inlet port 11 and high pressure fuel discharge port 12
And As is well known, the discharge ports 12 are provided in series by the number of cylinders, and each discharge port 12 is connected to the fuel injection valve 9 of each cylinder. Low pressure fuel inlet port 1
1 is connected to the diesel fuel supply passage 13,
Is connected to a diesel fuel tank (not shown) via a low-pressure fuel pump (crankshaft drive) not shown.

Next, in FIG. 1, reference numeral 15 indicates the whole fuel emulsifying apparatus according to the present invention. Referring to FIG. 2, the configuration of the fuel emulsifying device 15 will be described. The housing 16 is formed with a series of cylindrical recesses 18, 20, and 22 having a series of partially circular cross sections.
Gears 24, 26, 28 are eccentrically arranged.

As shown in FIG. 2, gears 24, 26, and 28 (supported by housing 16 by shafts 24A, 26A, and 28A, respectively) mesh in series. That is, the first gear 24 on the input side meshes with the intermediate second gear 26, and the second gear 26 meshes with the third gear 28 on the outlet side. The intermediate second gear 26 is a drive gear, and its central axis is connected to a drive source (not shown). The rotational movement of the intermediate gear rotated by the drive source is performed by the first gear 24 and the third gear via a meshing portion. 2
8 is transmitted. The direction of rotation is indicated by arrows A, B, and C in the figure. As a drive source of the drive gear 26, a belt drive may be performed by a crankshaft of the internal combustion engine, or a dedicated electric motor or hydraulic motor may be provided.

The eccentric arrangement of the respective gears 24, 26, 28 with respect to the cylindrical recesses 18, 20, 22 forms gaps 30, 32, 34 between the outer circumference of the gears and the inner circumference of the housing, respectively.
These gaps 30, 32, 34 are arranged so that the mesh point side is narrow and wide between them. In FIG. 1, this gap is considerably exaggerated, but at most 0.
It is about 5mm. Inner circumference of cylindrical recesses 18, 20, 22 and gears 24, 2
The gaps 30, 32, 34 between the outer circumferences of 6, 6 and 28 are connected in series, and the series connection of the gaps 30, 32, 34 constitutes a fuel emulsification passage in the present invention.

As shown in FIG. 1, one end (upstream side) of the diesel fuel introduction port 36 has a diesel fuel distribution passage 37.
To one end. The other end of the diesel fuel distribution passage 37 is connected to the fuel supply passage 13. The other end (downstream side) of the diesel fuel introduction port 36 is the second port as shown in FIG.
The first gear 24 is open to the gap 30 on the downstream side (inlet side of the emulsification passage) in the rotation direction of the first gear 24 close to the meshing portion with the gear 26.

In FIG. 2, the diesel fuel introduction port 3
6, an additional water introduction port 38 is opened upstream of the first gear 24 in the rotation direction. Additive water introduction port 38
Is connected to the additive water supply passage 40 as shown in FIG.
3 and connected to a water supply tank 44. 45 is a control circuit of the water supply pump 42. The effective diameter ratio between the fuel supply pipe from the diesel fuel introduction port 36 to the fuel injection pump 10 and the addition water pipe from the addition water introduction port 38 to the water supply pump 42 should be determined appropriately so as to obtain a predetermined water addition rate. Is a factor.

As shown in FIG. 2, the emulsified fuel outlet port 46
Is opened in the gap 34 (the outlet side of the emulsification passage) on the upstream side in the rotation direction of the third gear 28 in the vicinity of the meshing point of the third gear 28 with the second gear 26. As shown in FIG. 1, the emulsified fuel take-out port 46 is
Thus, the fuel injection pump 10 is connected to the passage 13 at a position close to the inlet port 11 of the fuel injection pump 10.

An adjusting screw 59 is provided at the emulsified fuel outlet port 46, and the flow rate of the emulsified fuel to the emulsified fuel supply passage 47 can be appropriately adjusted by adjusting the adjusting screw 59.

A throttle 61 is provided in the main fuel supply passage 13 between the junction with the branch passage 37 and the junction with the emulsified fuel passage 47, and the size of the throttle 61 is appropriately set. During normal operation, the entire amount of diesel fuel is diverted to the diversion passage 37 and the emulsifier 1
5, only the emulsified fuel from the emulsified fuel passage 47 can be supplied to the diesel engine, and excess emulsified fuel can be returned to the passage 37 to be emulsified again in the emulsified fuel passage 47.

As shown in FIG. 1, the emulsified fuel outlet port 46
Is also provided with a return passage 60, and a pressure control valve 62 is provided in the return passage. The pressure control valve 62 is configured to relieve fuel to the supply side when the fuel pressure exceeds a set pressure. That is, the pressure control valve 62 includes the housing 62-1 and
It is composed of a valve element 62-2, a spring 62-3, and a set screw 62-4. The spring load of the spring 62-3 is changed by adjusting the set screw 62-4, and the valve element 62-2 is changed by the spring load. When the valve opens, the emulsified fuel pressure changes. That is,
The emulsified fuel pressure can be appropriately adjusted by operating the set screw 62-4.

In the present invention, the housing 16 is placed vertically, the first gear 24 is located at the lowermost position, the second gear 26 is located at the middle, and the third gear 28 is located at the uppermost position. This positional relationship is such that when the engine is stopped, the separated water from the engine is stored at the bottom of the housing 16 and does not go to other parts, so that the fuel injection system such as the fuel injection pump 10 and the fuel injection valve 9 is vulnerable to residual moisture. It is important from the viewpoint of protection of parts.

Next, the operation of the engine forming mechanism of the present invention will be described. During normal operation of the internal combustion engine (when the key switch is ON), the discharge pressure P _{1 at} the emulsified fuel discharge port 46 of the emulsifier 15 is 0.6 kg / cm. connected low-pressure pump is a diesel fuel tank ² about (not shown) diesel fuel pressure P ₂ to the main fuel passage 13 (e.g., 0.5 kg / cm ²⁾
It is set higher (P ₁ > P ₂ ). A throttle 61 is provided in the main fuel passage 13 on the upstream side of the junction with the passage 47, and the diameter of the passage is appropriately reduced.
Therefore, only the emulsified fuel from the emulsifying device is guided to the fuel injection pump 10, and the diesel fuel (water-free fuel) from the low-pressure fuel pump does not go directly to the fuel injection pump 10. That is, all the diesel fuel (arrow 4) from the low-pressure fuel pump (not shown) enters the branch passage 37 from the main passage 13 and enters the arrow a (FIG. 2) from the fuel introduction port 36.
Is introduced into the emulsifying device 15 as shown in FIG.
8, additional water is introduced as indicated by arrow b. The arrow A indicates the additive water at the diesel fuel and additive water introduction port 38.
The gears 24 are carried in the rotational direction as shown by the arrow c by the tooth valleys of the first gear 24 rotating in the direction. When the diesel fuel + added water on the first gear 24 comes to a position P1 near the meshing point with the second gear 26, the gap 30 with the inner circumference of the housing 16 becomes narrower, and a part of the gap 30 becomes the second gear. Almost all dead ends also go toward the gap 32 between the gear 26 and the inner periphery of the housing 16, and flow backward along the inner periphery of the housing in a direction opposite to the rotation direction of the gear 24 as shown by an arrow d. Due to the eccentric arrangement of the gear 24 with respect to the housing, the gap 30 between the inner circumference of the housing 16 and the outer circumference of the first gear 24 once expands but narrows again, and the flow velocity at that time increases. FIG.
And in FIG. 3, the arrow d 'indicates the backflow along the inner circumference of the housing at a high speed. On the other hand, the mixture of fuel and water is carried in the direction of rotation of the gears (direction of arrow c (forward direction)). Among them, the water of high specific gravity is left in the tooth valley and the first gear 24 which rotates in the direction of arrow A. Is scattered outward as indicated by F in FIG. The water F thus scattered at high speed is subjected to an intense shearing action by the fluid flowing backward as indicated by arrow d '. And the first gear 2
At a position P2 between the outer periphery of the housing 4 and the inner periphery of the housing.
Becomes narrower, so there is no place to go, and the direction changes again.
(Forward). By the repetition of the shearing action due to the encounter of the forward flow on the inner peripheral side and the reverse flow on the outer peripheral side, the pulverizing action to the extremely fine water droplets is achieved, and the gap 32 between the second gear 26 and the housing 16 is formed. The discharged fluid can be subjected to a high degree of emulsification.

The emulsified fuel that has flowed into the gap 32 between the second gear 26 and the housing 16 is subjected to the same repeated reversal of the flow direction due to the limited locations at both ends. That is, water flows in the forward direction e according to the rotation direction B of the second gear on the inner layer side (tooth valley side), and flows in the opposite direction f on the outer layer side (the inner peripheral side of the housing). Is extremely miniaturized. And the third gear 2
In FIG. 8, an inner laminar flow (arrow g) following the gear rotation direction (arrow C) at the tooth valley and an outer laminar flow (arrow h) at the inner periphery of the housing 16 are obtained. Water droplet subdivision is further advanced. With such a multi-stage (three-stage in this embodiment) arrangement, repetitive atomization is performed in each stage, so that the fuel is finally discharged from the fuel outlet port 46 toward the inlet port 11 of the fuel injection pump 10 as shown by an arrow i. The fuel emulsification which can be said to be ideal when the fuel is taken out is realized.

The emulsified fuel thus ideally emulsified is introduced into the intake port of the fuel injection pump 10 from the intake port 11 through the passage 13 through the passage 47 in FIG. The fuel is sent to the injection valves 9 and is injected from the fuel injection valves 9 into the respective cylinder combustion chambers at the fuel injection timing.

The idealized emulsified fuel is introduced into the fuel injection pump 10 from the suction port 11 through the passage 47 through the passage 13 in FIG. The fuel is sent to the injection valve 9 and is injected into each cylinder combustion chamber from each fuel injection valve at a fuel injection timing.

For the emulsification operation of the present invention described above, important points will be described with respect to the intermeshing structure of the gears 24, 26, 28 and the positional relationship between the outer periphery of the gears 24, 26, 28 and the inner periphery of the housing 16. First, in the positional relationship between the first gear 24 and the housing 16, the airtightness between the outer circumference of the first gear 24 and the inner circumference of the housing at the position P3 before the ports 36 and 38 in the rotation direction (arrow A). is important. That is,
Due to such airtightness, the rotation of the first gear 24 causes a negative pressure to occur at the tooth valley portion, and can cause the suction of the diesel fuel and the additional water from the ports 36 and 38 opposed thereto. Further, a meshing point P4 between the first gear 24 and the second gear
The airtightness between the second gear 26 and the inner periphery of the housing 16 at the position P5 facing the second gap 32 is also important. Such airtightness enables good emulsification by forming a repetitive flow of the fluid from the first gap 30 in the second gap 32.

The water supply pump 42 for controlling water addition is an electric pump such as an electromagnetic type, and the control circuit 45 controls the water supply pump 42 so as to control the water addition following a change in the flow rate of the fuel. An optimal amount of water can always be added following a change in fuel flow rate due to operating conditions.

When the engine is stopped (at key-off), the motor for driving the emulsifying device is immediately stopped, so that the pressure at the emulsified fuel discharge port 46 is immediately reduced, and pure diesel fuel (added water) is supplied from the low-pressure fuel pump. Is not added) is the passage 13
It is directly introduced into the fuel injection pump 10 from the suction port 11 via the (throttle 61). The operation for a while (several minutes) is continued by such a normal diesel fuel to which no added water is added. That is, the operation of the drive motor of the fuel emulsification device 15 is immediately stopped in response to the key-off operation, but appropriate means is provided for delaying the stop of the diesel engine for several minutes. For example, a delay circuit (such a delay circuit itself is known) that delays the actual stoppage of the fuel supply from the diesel fuel tank in response to a key-off is provided. Therefore, the emulsified fuel remaining in the fuel piping system from the fuel injection pump 10 to the fuel injection valve 9 is completely replaced with the normal fuel. Therefore, it is possible to completely eliminate the adverse effects caused by the water separation from the emulsified fuel and the mayonnaise phenomenon that may occur if moisture remains.

When the diesel engine is stopped, the housing 16 is filled with the emulsified fuel, but in the case of light oil or the like, the fuel and water separate in a relatively short time, and the water is relatively heavy. It collects from the bottom. In the embodiment of the present invention, the gears 24, 26, 28 in the housing 16 are set vertically,
Since the first gear 24 on the inlet side is located at the lowermost position, the separated water only accumulates at the bottom of the housing 16, and the water accumulated at the bottom of the housing increases in viscosity with time and becomes mayonnaise. Yes, but the next time the engine is run, it will be highly crushed by the repetitive shearing action that it receives again when passing through gaps 30, 32, 34,
It can again be supplied to the combustion chamber as well emulsified fuel. If necessary, as shown in FIG.
6, a drain passage 93 is provided at the bottom of the drain passage 93.
An opening / closing valve 94 is provided in the housing 16 and the opening / closing valve 94 is normally closed. However, by opening the opening and closing when necessary, water accumulated in the housing 16 can be discharged by an electric pump.

In FIG. 1, irregularities 100 and 102 can be appropriately provided on the cylindrical inner peripheral surface of the housing.
Due to 02, turbulence such as a vortex occurs in the flow, which can contribute to the fragmentation of water droplets.

In the above embodiment, although the fuel injection pump 10 has a return circuit (not shown) for returning to the fuel tank, a switching means (a three-way valve) for returning the fuel from the return circuit to the suction side of the emulsifier. Etc.) can be installed.

In the above description, the fuel injection pump 10 has been described as a row type. The row type pump is preferable because the capacity of the fuel reservoir is relatively small, so that the time required to replace the fuel with water-free fuel when the engine is stopped is reduced. Further, diesel exhaust gas regulations are being applied to large trucks, and row trucks are mainly used for large trucks, which is preferable. However, it is naturally possible to implement the present invention with a distribution type fuel injection pump.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a fuel supply system for a diesel engine equipped with a fuel emulsification device according to the present invention.

FIG. 2 is an enlarged view of the fuel emulsification device of FIG. 1;

FIG. 3 is a partially enlarged view of the fuel emulsifying device of FIG. 2, illustrating the principle of crushing water droplets according to the present invention.

[Explanation of symbols]

 8: Diesel engine body 9: Fuel injection valve 10: Fuel injection pump 11: Inlet port 12: Discharge port 15: Fuel emulsifier 16: Housing 18, 20, 22 ... Cylindrical recess 24, 26, 28 ... Gear 30, 32, 34: gap forming an emulsified fuel passage 36 ... diesel fuel introduction port 38 ... additive water supply passage 46 ... emulsified fuel takeout port 47 ... emulsified fuel supply passage 59 ... adjust screw 60 ... return passage 61 ... throttle 62 ... pressure control valve

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02M 43/00 F02M 55/00 D 55/00 F04C 11/00 F F04C 11/00 15/00 G 15 / 00 F02M 25/02 K ATF term (reference) 3G066 AA07 AB02 AB06 AB08 AC02 AC06 AD12 BA23 BA28 CB16 DB19 3G092 AA02 AA06 AA08 AB03 AB04 AB15 BB10 BB20 CA01 CB05 CB06 CB07 CB08 EA03 EA12 EA03 EA03 HA24 JA24 JA25 JA26 KA28 LB07 LB13 MA00 NE22 PF16Z 3H044 AA02 BB02 CC00 CC19 DD03 DD05 DD07 DD15 DD16 DD19

Claims (7)

[Claims] 1. A fuel emulsifying means for emulsifying a fuel supplied to an internal combustion engine by adding water thereto, wherein said fuel emulsifying means is engaged with a housing in a series and each of the fuel emulsifying means is in contact with a circumferential surface of the housing. A plurality of gears arranged opposite to each other, and a rotation driving means for the gears are formed, and a circumferential gap is formed between the outer peripheral surface of each gear and the circumferential surface of the housing, the circumferential gap varying in the circumferential direction. The circumferential gap is connected in series to form a fuel emulsification passage, fuel and added water are supplied to the emulsification passage from one end thereof, and the emulsified fuel is taken out from the other end of the emulsification passage to the internal combustion engine. And an engine stop-time control unit for invalidating the operation of the fuel emulsification unit prior to the stop of the engine and continuing the operation in a state where the water-free fuel is supplied to the engine for a while. Fuel supply device for internal combustion engine. 2. The internal combustion engine according to claim 1, wherein the engine stop time control means automatically switches between the emulsified fuel supply and the water-free fuel supply based on the emulsified fuel discharge pressure itself. Fuel supply system. 3. The fuel emulsification device for an internal combustion engine according to claim 1, wherein the internal combustion engine is a diesel engine. 4. The fuel emulsification device for an internal combustion engine according to claim 1, wherein the gear is disposed vertically and a supply side is located below a discharge side. 5. A fuel emulsification device for an internal combustion engine according to claim 4, wherein a forced drainage means for drain water is provided at a bottom of the housing. 6. A fuel emulsification apparatus for an internal combustion engine according to claim 1, further comprising an electric pump for controlling water addition following a change in fuel flow rate. 7. The fuel emulsification for an internal combustion engine according to claim 1, wherein a switching means for returning the fuel to the suction side of the emulsifier is provided in a circuit returning from the fuel injection pump to the fuel tank. apparatus.