JPH09144606A - Fuel and water injection engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lower the level of the rate of NOx in discharge gas effectively by providing with a control device for controlling a rate for supplying fuel toward the fuel passage of a fuel pump, a rate for supplying water toward the water passage of a water supplying pump, and the opening degree of an EGR valve respectively. SOLUTION: The output signal Ne of a speed sensor 56 for detecting the speed of an engine and the output signal Tw of a temperature sensor 58 for detecting the cooling water temperature of the engine are received and stored in a control unit or a control device 64. And also the output signal Lp of a lever position sensor 60 for detecting the load of an engine 10 and the output signal Ti of an intake temperature sensor 34 are received and stored therein. An actuator 62 for setting the opening degree of an EGR valve 32 is controlled by the control unit or the control device 64. A rate for supplying fuel toward the fuel passage of a fuel injection pump 36 and a rate for supplying water toward the water passage of a water supplying pump 46 are controlled. It is thus possible to reduce a rate of NOx to more extent without accompanying failure of increase of the level of the rate of HC in exhaust gas and smoke.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel and a fuel for injecting fuel such as light oil and water into a combustion chamber of the engine when the engine is operating in a region above a preset load. It relates to a water injection engine.

[0002]

2. Description of the Related Art In a diesel engine for vehicles such as trucks, a method of injecting fuel such as light oil and water into a combustion chamber of the engine is effective for reducing harmful components in exhaust gas, particularly NO _x. This is generally well known, for example, in Japanese Utility Model Laid-Open No. 4-104156,
One example is disclosed. Actual Kaihei 4-10415
In a normal fuel and water injection engine including an engine equipped with an injection device proposed in Japanese Patent No. 6 (hereinafter, referred to as an already proposed engine), the vertical axis indicates the engine load, and the horizontal axis indicates engine rotation. In FIG. 9 showing the number N _e , the shaded middle and high load region A, for example, 45%
Fuel and water are injected in the operating region above the load, and in the white low load region, for example, in the operating region below 45% load, water injection makes the operation unstable or impossible, so only fuel is injected. To be done.

In the above proposed engine, the vertical axis represents the injection pressure and the horizontal axis represents the crank angle.
As shown in the diagram showing the injection pattern of 0,
First, a certain amount, for example, 50 mm ³ / st of the initial fuel F _f is injected, and then a variable amount of water W set according to the operating state of the engine is injected, and subsequently the latter fuel F f is injected. The injection of _r is performed.

In the above-mentioned proposed engine, even in the operating region A where fuel and water are injected, the initially injected initial fuel F _f is still low in the part where the load is low depending on the engine speed and load. When the fuel does not ignite or is insufficiently ignited, water is subsequently injected, so that the ignition delay is large and the HC in the exhaust gas tends to increase. In the low / medium load region B where the injection amount of F _r is, for example, 50 mm ³ / st or less, water injection is not performed and only fuel is injected to operate, so that NO _x in the exhaust gas cannot be reduced. There is.

On the other hand, it is well known that NO _x in the exhaust gas can be reduced by extracting a part of the exhaust gas of the engine and returning it to the combustion chamber of each cylinder of the engine together with the intake air. However, in the case of a diesel engine, in the medium and high load operating region, for example, in the relatively high load portion in the operating region A of FIG. 9, if exhaust gas recirculation sufficient for NO _x reduction is performed, fuel combustion becomes insufficient. Since the smoke becomes significantly worse, the exhaust gas is not normally recirculated,
Therefore, there is a disadvantage that a sufficient NO _x reduction effect cannot be obtained in this operating region.

[0006]

SUMMARY OF THE INVENTION The present invention was devised in view of the above circumstances, and in the entire operating region of the engine, without increasing HC and worsening smoke,
NO _x in the exhaust gas can be effectively reduced,
The main object of the present invention is to provide a fuel and water injection engine suitable for use in a diesel engine for vehicles.

[0007]

In order to achieve the above object, the present invention is slidably fitted in a nozzle body having a nozzle hole at its tip and is always elastically biased in the closing direction. A needle valve, a fuel reservoir formed in the nozzle body so as to face the needle valve, and provided in the nozzle body, one end of which is connected to the fuel reservoir and the other end of which is connected to the fuel injection pump. A fuel passage communicated with the nozzle body, one end of which communicates with a fuel passage upstream of the fuel reservoir and the other end of which pumps water at a pressure lower than the opening pressure of the needle valve. Having a water passage communicated with the water supply pump, and after water is supplied to the fuel passage from the water supply pump via the water passage during a fuel supply suspension period to the fuel passage of the fuel injection pump, Fuel is supplied from the fuel injection pump to the fuel passage. The fuel and water injector configured to inject fuel and water from the injection hole when the needle valve is opened, and exhaust gas recirculation for recirculating a part of engine exhaust gas to the combustion chamber of the engine. The passage, the variable opening EGR valve interposed in the exhaust gas recirculation passage, and the fuel supply amount to the fuel passage of the fuel injection pump and the water passage of the water supply pump according to the operating state of the engine. The present invention proposes a fuel and water injection engine including a control device for controlling the water supply amount and the opening degree of the EGR valve, respectively.

In the present invention, the control device operates the water supply pump in an operating region where the load of the engine exceeds the set load, and supplies water to the water passage during a fuel supply suspension period of the fuel injection pump. At the same time, it is preferable that the EGR valve is opened and the exhaust gas is recirculated in both the operating region where the load is lower than the set load of the engine and the operating region where the load exceeds the set load. Further, the EGR valve is provided in the exhaust gas recirculation passage that guides the exhaust gas to the intake passage of the engine, and the intake passage for detecting the temperature of the intake air into which the exhaust gas is introduced is provided in the intake passage downstream of the exhaust gas recirculation passage. A temperature sensor is provided, and the control device controls the opening degree of the EGR valve so that the intake air temperature detected by the intake air temperature sensor becomes substantially equal to the set temperature set according to the engine load. It is desirable to be configured to.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be specifically described below with reference to the accompanying drawings. First, in the schematic configuration diagram shown in FIG. 1, reference numeral 10 conceptually represents a direct injection diesel engine for a vehicle.
Is equipped with a piston 16 slidably fitted in a cylinder 12 and having a combustion chamber cavity 14 of an appropriate shape (toroidal type in the case shown) recessed in the top thereof.
6 rotates a crankshaft (not shown) via a connecting rod 18.

Each cylinder 12 is provided with at least one intake valve 20 and at least one exhaust valve 22, and further the fuel injection valve 2 is provided.
4 are provided. The intake valve 20 controls communication between the intake passage 26 and the cylinder 12, and the exhaust valve 22 controls communication between the exhaust passage 28 and the cylinder 12. An exhaust gas recirculation passage 30 is provided between the intake passage 26 and the exhaust passage 28.
Is provided, and an EGR valve 32 having a variable opening degree is provided in the exhaust gas recirculation passage 30. The EGR valve 32 has
A poppet valve similar to the normal intake valve 20 and exhaust valve 22,
Alternatively, a butterfly valve or the like can be appropriately adopted.
An intake air temperature sensor 34 is provided in the intake passage 26 on the downstream side of the connecting portion of the exhaust gas recirculation passage 30, and the intake air temperature sensor 34 detects the outside air taken in and the recirculation exhaust gas flowing from the exhaust gas recirculation passage 30. Detects the temperature of mixed intake air.

Further, the fuel injection valve 24 is supplied with high-pressure fuel from an ordinary fuel injection pump 36 (in the case shown, a column fuel injection pump is shown) through a fuel injection pipe. The fuel injection pump 36 pressurizes fuel such as light oil, which is stored in a fuel tank 40 and is pumped up by a feed pump 42 and filtered by a filter 44, to a desired high pressure so that each cylinder of the engine 10 undergoes a compression stroke. When the fuel injection valve 2 is in the vicinity of the top dead center through the fuel injection pipe 38,
4 Further, water is supplied to the fuel injection valve 24 from a water supply pump 46 (in the case shown, a row type injection pump having the same structure as the fuel injection pump 36 is illustrated) via a water injection pipe 48. The water supply pump 46 pressurizes the water stored in the water tank 50, pumped by the feed pump 52, and filtered by the filter 54 to an appropriate pressure lower than the valve opening pressure of the fuel injection valve 24,
It is pressure-fed to the water injection pipe 48 at a timing and a discharge amount which will be described in detail later. Furthermore, the EGR valve 32 is provided with various signals or information indicating the operating state of the engine 10, that is, an output signal N _e of a rotation speed sensor 56 that detects the rotation speed of the engine, and a temperature sensor that detects the cooling water temperature of the engine. output signal T _w of _58, the output signal L _p of the lever position sensor 60 for detecting a load of the engine 10 by detecting the position of the control lever for determining the fuel supply amount of the fuel injection pump _36, and the intake air temperature sensor The opening degree of the EGR valve is controlled by a control unit or controller 64 that receives the output signal T _i of the control signal 34 and supplies a drive output to the actuator 62 for setting the opening degree of the EGR valve.

Next, the fuel injection valve 24, as shown in the sectional view of FIG. 2 and the partially enlarged sectional view of FIG.
A nozzle body 68 having a plurality of injection holes 66, a distance piece 70, and a nozzle holder 72 are provided at a tip end portion of each cylinder of the engine facing the cylinder 12, and the nozzle body 68 and the nozzle holder 72 are provided at an intermediate distance. With the retaining nut 74 sandwiching the piece 70,
Are united together. In the nozzle body 68,
A needle valve 76 for controlling the opening and closing of the injection hole 66 is slidably fitted in the vertical direction in the figure, and the needle valve 76 is bent and bent to enclose the fuel reservoir 7.
8 are formed. Further, a fuel passage 80 having one end communicating with the fuel reservoir 78 is provided in the nozzle body 68, and the other end of the fuel passage 80 has a distance piece 70.
And the fuel passages 80a and 80b in the nozzle holder 72,
Further, it is connected to the discharge port of the fuel injection pump 36 via a fuel injection pipe 38 and a constant pressure valve 82 known per se. Further, in the nozzle body 68, a water passage 84, one end of which communicates with a fuel passage 80 on the upstream side of the fuel reservoir 78, is provided.
The other end of the water passage 84 is connected to the discharge port of the water supply pump 46 via the water passages 84a and 84b in the distance piece 70 and the nozzle holder 72, and the water injection pipe 48, and upstream of the water passage 84a. A check valve 90 including a ball valve 86 and a set spring 88 is provided at the end.

A spring chamber 92 is provided inside the nozzle holder 72 substantially coaxially with the needle valve 76.
A first pressure spring 92 and a second pressure spring 94 that normally bias the needle valve 76 in the closing direction are housed in the spring chamber 92. When the high-pressure fuel is discharged from the fuel injection pump 36 and the pressure of the high-pressure fuel acts on the fuel reservoir 78 via the fuel passages 80a, 80b and 80 of the fuel injection valve 24, the valve opening that acts on the step portion of the needle valve 76. The first pressure spring 9 by the pressure in the direction.
4 is overcome and the needle valve 76 is lifted to open the injection hole 66. The valve opening pressure is 180 as an example.
It is set to kg / cm ² . After the injection from the injection hole 66 is completed, the fuel passages 80, 80a, 80b and the fuel injection pipe 3 are driven by the well-known equal pressure action of the constant pressure valve 82.
The pressure in 8 is set to a constant pressure sufficiently lower than the valve opening pressure of 180 kg / cm ² , for example, 60 kg / cm ² . Further, the discharge water pressure of the water supply pump 46 is the valve opening pressure 180 kg / cm ² and the set pressure 60 of the constant pressure valve 82.
appropriate intermediate pressure between kg / cm ^2, for example 1:80
It is set to 00 kg / cm ² .

In the above fuel and water injection device, in the operating region where the load of the engine 10 is a preset load, for example, 45% load or more, that is, in the region A of FIG. 4, in accordance with a command from the control unit or the control device 64, The high-pressure water discharged from the water supply pump 46 is supplied to the water passage 84b via the check valve 90 during the supply stop period in which the high-pressure fuel is not supplied to the fuel injection valve 24 from the fuel injection pump 36. In addition, the drive output is provided to the actuator 62 for setting the EGR valve opening degree in the entire area of the medium-high load operation area A or in most areas except the vicinity of the maximum load described later, and the EGR valve opening degree is set.
The valve 32 is opened at an appropriate opening, and the exhaust passage 2 of the engine 10 is opened.
A part of the exhaust gas flowing through 8 is supplied from the recirculation passage 30 to the intake passage 26 via the EGR valve 32, and is supplied into the cylinder 12 of the engine together with the intake air.

When high-pressure water is supplied to the water passage 84b of the fuel injection valve 24 in the medium / high load operation region A, the fuel pressure in the fuel passage 80 set by the constant pressure valve 82 of the fuel injection pump 36 is increased. Since the pressure of the water is lower than that of the water, as shown in FIG. 3, the water shown in satin in the drawing removes the fuel in the fuel passage 80 and discharges the fuel into the fuel passage 80 by the amount of discharge water. Inflow. Then, when high-pressure fuel exceeding the valve opening pressure is supplied from the fuel injection pump 36,
The needle valve 76 is opened, and as shown in FIG. 10, the initial fuel F _f is first injected from the injection hole 66, and then the water W is injected, and subsequently the latter fuel F _r is injected. Of course, the total amount of injected fuel F _f + F _r is set according to the operating state of the engine 10.

As described above, in the operating region A, the water is injected and the exhaust gas is recirculated, so that
The temperature of intake air becomes high, the tendency of ignition delay at the time of water injection is improved, and the ignitability is improved. In particular, since the ignitability in the relatively low load region where the tendency of ignition delay is remarkable in the past is improved, the increase in HC in the exhaust gas is mainly caused by the effect of water injection and the effect of a slight exhaust gas recirculation. A reduction of NO _x can be effectively achieved while suppressing. On the other hand, in the low / medium load region B of FIG. 4, the EGR is performed by the drive output of the control unit or the control device 64.
The actuator 62 for setting the valve opening is operated to open the EGR valve 32, the exhaust gas is recirculated, and the supply of high-pressure water from the water supply pump 46 to the fuel injection valve 24 is stopped. Therefore, in the operating region B, the NO _{x in} the exhaust gas is reduced by the recirculation of the exhaust gas.

FIG. 8 shows E in the above operating regions A and B.
It is an example of a GR valve opening control map. In this example, as indicated by a line α in the figure, the valve opening degree at the minimum load at which the recirculation of the exhaust gas is essentially difficult is 100 because the differential pressure between the exhaust gas pressure and the intake pressure is small. %, And the valve opening at the maximum load is set to 0, and the valve opening at the intermediate load is linearly changed. Of course, this characteristic line α depends on the type of engine to reduce NO _x . The effect and the exacerbation of smoke that tends to occur due to exhaust gas recirculation are experimentally confirmed and compared to determine a preferable characteristic line G. It should be noted that the maximum load portion of the illustrated line α is partially indicated by a dotted line because the maximum load and the adjacent high load portion have a relatively large fuel amount with respect to the oxygen amount in the intake air, In many engines, smoke tends to worsen and there is a possibility that the exhaust gas recirculation may have to be stopped.

Next, FIG. 7 shows an example of a water injection amount control map in which the vertical axis represents the ratio of the injection water amount to the fuel amount and the horizontal axis represents the engine load. As shown by the line β in the figure, in the operating region where the load is less than 45%, water injection is not performed, and the injection amount increases linearly from 45% to 70% load, and when the load is 70% or more, the maximum Injection amount 50%
Becomes Of course, the water injection characteristics are appropriately changed and modified depending on the type of engine by comprehensively considering the effect of reducing NO _{x in} exhaust gas, the increase of HC, the deterioration of smoke, and the like.

FIG. 5 shows the NO _x emission characteristics of the fuel and water injection engine according to the present invention described above, with the vertical axis representing the NO _x amount in the exhaust gas and the horizontal axis representing the engine load. is there. The solid line γ in the figure represents the engine according to the present invention, and the dashed line γ'indicates the NO _x and emission amount of the base engine that does not recirculate exhaust gas or inject water. . As shown by the line γ, in the low-medium load operating region B where the set load is less than 45%, NO _x gradually increases with the load, and when the set load is 45% or more, water injection and exhaust gas recirculation are performed. , NO _x changes at a level close to a substantially straight line. However, by comparing it with the line γ'representing the NO _x amount of the base engine that does not perform exhaust gas recirculation or water injection, as will be immediately understood, a large N
O _x reduction is achieved. The dotted line γ ″ described in the operating region A in which the set load is exceeded indicates the NO _x amount when water injection is not performed in this operating region and only exhaust gas recirculation is performed.

Further, in FIG. 6, the vertical axis represents the smoke concentration (smoke).
FIG. 4 is a diagram in which the smoke load is examined by taking the engine load on the horizontal axis. In the figure, σ indicated by the solid line indicates the smoke concentration of the fuel and water injection engine, and line σ ′ indicated by the alternate long and short dash line indicates the smoke concentration of the base engine. The dotted line σ ″ in the figure shows the smoke concentration when water injection is not performed and only exhaust gas recirculation is performed in the medium-high load operation region A above the set load. As shown in the figure, water injection and exhaust gas recirculation By simultaneously performing and, it is possible to effectively prevent the deterioration of the smoke performance.

As described above, in the present invention, the main purpose of the exhaust gas recirculation in the medium and high load operation region A is to increase the temperature of the intake air by adding the high temperature exhaust gas, and It is to reduce NO _x while preventing deterioration of ignitability and effectively suppressing increase of HC in exhaust gas and deterioration of smoke.
The intake air temperature which can ensure the ignitability of the fuel despite water injection and the set temperature T _o, the control unit or control the deviation between the sensed intake air temperature T _i and the set air temperature T _o by the intake air temperature sensor 34 Calculated in the device 64,
It is extremely advantageous to control the opening degree of the EGR valve 32 by giving a drive output according to the deviation to the actuator 62, especially when the outside air temperature is low. The set intake air temperature _{T o}
May be a temperature that changes according to the engine load, and may be a certain constant temperature within the medium-high load operating region A, for example, 40
It is good also as ° C. In the EGR valve opening diagram of FIG. 8, this is the opening that gradually decreases according to the load in the operating region where the engine load is equal to or lower than the set load (line α in the figure),
In the medium to high operating range, it means that the line α is modified to a curve or a straight line related to the load and the intake air temperature.

The engine cooling water temperature T _w is detected by the temperature sensor 58, and the cooling water temperature T _w is set to, for example, 6
At the time of cold start at 0 ° C. or less, the control unit or the control device 64 causes the actuator 62 to move the EGR valve 3
A drive output for fully closing 2 is supplied, and exhaust gas is not recirculated.

[0023]

As described above, the fuel and water injection device according to the present invention is slidably fitted in a nozzle body having an injection hole at its tip and is always elastically attached in the closing direction. A biased needle valve, a fuel reservoir formed in the nozzle body facing the needle valve, and provided in the nozzle body, one end of which communicates with the fuel reservoir and the other end of which fuel is injected. A fuel passage communicated with a pump and provided in the nozzle body, one end of which communicates with a fuel passage upstream of the fuel reservoir, and the other end of which has a water pressure lower than the valve opening pressure of the needle valve. And a water passage communicating with a water supply pump for pumping water, and water is supplied from the water supply pump to the fuel passage through the water passage during a fuel supply suspension period to the fuel passage of the fuel injection pump. Later, fuel is supplied from the fuel injection pump to the fuel passage. By opening the said needle valve is,
A fuel and water injection device configured to inject fuel and water from the injection holes, an exhaust gas recirculation passage for recirculating a part of engine exhaust gas to a combustion chamber of the engine, and an exhaust gas recirculation passage interposed therein. Variable opening EGR valve, and the fuel supply amount to the fuel passage of the fuel injection pump, the water supply amount to the water passage of the water supply pump, and the opening degree of the EGR valve according to the operating state of the engine. It is characterized in that it is equipped with a control device for controlling each of the above, and has an advantage that NO _x can be further reduced as compared with a conventional engine of the same type without causing a problem of increase in HC and smoke in exhaust gas.

Further, the control device operates the water supply pump in an operating region where the load of the engine exceeds the set load, supplies water to the water passage during the fuel supply suspension period of the fuel injection pump, and By operating the EGR valve to operate so as to recirculate exhaust gas in both an operating range of a load lower than the set load of the engine and an operating range exceeding the set load of the engine, exhaust gas is exhausted in the entire operating range of the engine. There is an advantage that the NO _x can be effectively reduced. Further, the EGR valve is provided in the exhaust gas recirculation passage that guides the exhaust gas to the intake passage of the engine, and the intake passage for detecting the temperature of the intake air into which the exhaust gas is introduced is provided in the intake passage downstream of the exhaust gas recirculation passage. A temperature sensor is provided, and the control device controls the opening degree of the EGR valve so that the intake air temperature detected by the intake air temperature sensor becomes substantially equal to the set temperature set according to the engine load. Therefore, there is an advantage that the ignitability can be effectively improved and NO _x in the exhaust gas can be effectively reduced even in a state where the outside air temperature is low in which the ignitability is apt to be deteriorated.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a preferred embodiment of the present invention.

FIG. 2 is a detailed configuration diagram showing a cross section of a main part of the fuel and water injection device in FIG.

3 is an enlarged cross-sectional view of a tip portion of a fuel injection valve 24 in FIG.

FIG. 4 is a diagram showing an operating region in which only exhaust gas recirculation is performed and an operating region in which both water injection and exhaust gas recirculation are performed in the present invention.

FIG. 5 is a diagram showing the relationship between the engine load and the NO _x emission amount according to the present invention.

FIG. 6 is a diagram showing a relationship between engine load and smoke concentration according to the present invention.

FIG. 7 is a diagram showing the relationship between the engine load and the water injection amount according to the present invention.

FIG. 8 is a diagram showing the relationship between the engine load and the EGR valve opening according to the present invention.

FIG. 9 is a diagram showing an operating region of a conventional fuel and water injection engine.

FIG. 10 is a diagram showing an injection pattern of a fuel and water injection engine.

[Explanation of symbols]

10 ... Engine, 12 ... Cylinder, 14 ... Combustion chamber cavity, 16 ... Piston, 20 ... Intake valve, 22 ... Exhaust valve,
24 ... Fuel injection valve, 26 ... Intake passage, 28 ... Exhaust passage,
30 ... Exhaust gas recirculation passage, 32 ... EGR valve, 34 ... Intake air temperature sensor, 36 ... Fuel injection pump, 46 ... Water supply pump, 56 ... Rotation speed sensor, 58 ... Temperature sensor, 60 ... Control lever position sensor, 62 ... EGR valve opening control actuator, 64 ... Control unit or control device, 66 ... Injection hole, 68 ... Nozzle body, 70 ... Distance piece, 72 ... Nozzle holder, 76 ... Needle valve, 7
8 ... Fuel reservoir, 80 ... Fuel passage, 82 ... Constant pressure valve, 84 ... Water passage, 90 ... Check valve, 92 ... Spring chamber, 94 and 9
6 ... Pressure spring.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location F02M 25/07 550 F02M 25/07 550K 550R 43/04 43/04 61/10 61/10 P 25 / 02 KR

Claims (3)

[Claims] 1. A needle valve slidably fitted in a nozzle body having a nozzle hole at its tip and constantly elastically biased in a closing direction, and a needle valve facing the needle valve in the nozzle body. And a fuel passage provided in the nozzle body, one end of which is connected to the fuel reservoir and the other end of which is connected to a fuel injection pump, and the fuel passage which is formed in the nozzle body. One end thereof is connected to a fuel passage upstream of the fuel reservoir, and the other end thereof has a water passage communicated with a water supply pump that pumps water at a pressure lower than the valve opening pressure of the needle valve, After the water is supplied from the water supply pump to the fuel passage through the water passage during the fuel supply stop period to the fuel passage of the fuel injection pump, the fuel is supplied from the fuel injection pump to the fuel passage. By opening the needle valve, fuel is injected from the injection hole. And a fuel and water injection device configured to inject water, an exhaust gas recirculation passage for recirculating a part of engine exhaust gas to the combustion chamber of the engine, and a variable opening degree interposed in the exhaust gas recirculation passage. Control for controlling the fuel supply amount to the fuel passage of the fuel injection pump, the water supply amount to the water passage of the water supply pump, and the opening degree of the EGR valve according to the operating state of the EGR valve and the engine A fuel and water injection engine comprising a device. 2. The control device operates the water supply pump in an operating region where the load of the engine exceeds a set load, supplies water to the water passage during a fuel supply suspension period of the fuel injection pump, and 2. The fuel and water injection engine according to claim 1, wherein the EGR valve is opened to recirculate exhaust gas in both an operating region where the load is lower than the set load of the engine and an operating region where the load exceeds the set load. 3. The EGR valve is provided in an exhaust gas recirculation passage that guides the exhaust gas to an intake passage of an engine, and the temperature of intake air into which the exhaust gas is introduced is controlled in an intake passage downstream of the exhaust gas recirculation passage. An intake air temperature sensor for detecting is provided, and the control device controls the opening degree of the EGR valve so that the intake air temperature detected by the intake air temperature sensor becomes substantially equal to the set temperature set according to the engine load. The fuel and water injection engine according to claim 1 or 2, which is controlled.