JP2668026B2 - Diesel engine fuel injection system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device for a diesel engine, which is suitable for a so-called water injection type diesel engine, in which fuel and water are mixed and injected into a combustion chamber to perform combustion.

[0002]

2. Description of the Related Art In a diesel engine, the combustion is performed by so-called in-cylinder injection compression ignition, so that the generation mechanism of each component contained in the exhaust gas is different from that of gasoline premixed combustion. That is, in a diesel engine, combustion is generally performed in a state of excess air,
The emission concentrations of HC and CO are relatively low, whereas the combustion temperature is high, so a large amount of NOx is generated. In addition, injection combustion is performed, and as a result of locally exposing fuel vapor or an excessively rich mixture to a high-temperature atmosphere, fuel molecules are thermally decomposed and carbon particles are easily formed. For this reason, there is a problem that a large amount of soot is discharged into the exhaust gas. In particular, when the load is high, the combustion temperature rises and NOx
Is promoted, and the fuel density is higher than that under low load, so that the chances that the carbon particles come in contact with air again are reduced, and more soot is discharged.

In order to deal with the above problem, a so-called water injection type diesel engine has been proposed in which fuel and water are mixed and injected into the combustion chamber for combustion. In this water-injection type diesel engine, water is injected into the combustion chamber together with fuel during fuel injection, so that firstly, the combustion temperature is reduced and the generation of NOx is suppressed. Further, a small explosion due to vaporization of water, that is, a water divergence phenomenon occurs, a vortex flow is generated in the combustion chamber, combustion efficiency is improved, and soot generation is suppressed. Furthermore, the improvement of the combustion efficiency will improve the fuel efficiency.

[0004]

However, in the conventional fuel injection device for a diesel engine, water injection is always performed irrespective of the operating state of the engine.
For example, when the temperature is low, there is a problem that ignitability of the fuel mixture is deteriorated to make it difficult to start the engine, and white smoke is emitted after the start. Water injection is also performed at low temperatures where the air density is high relative to the fuel and soot emissions are reduced, or at low loads where both NOx and soot emissions are reduced. There is a problem that the device is not always used efficiently.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem, and it has been proposed to improve low-temperature startability, prevent the emission of white smoke after starting, and efficiently use water and a water injection device. It is an object of the present invention to provide a fuel injection device for a diesel engine which is operated to reduce the emission of NOx and soot.

[0006]

To achieve the above object, according to the present invention, a fuel pump for pumping fuel,
Water pump for pumping water, and fuel injection nozzle for injecting fuel and water, which is pumped by the fuel pump and the water pump into the combustion chamber of the engine, under pressure from the fuel pump
A fuel amount changing means for changing a fuel amount to be supplied;
Means for changing the amount of water pumped from the pump;
The fuel amount changing means based on an operation state of the engine;
Means for controlling the fuel amount, and detecting the temperature of the engine.
Engine temperature sensor that emits air and atmosphere that detects atmospheric temperature
A temperature sensor and an engine for detecting a load of the engine
Detected by a load sensor and the engine temperature sensor.
Engine temperature is lower than a predetermined first set temperature
When controlling the water amount changing means to stop the pumping of water
And the engine temperature is equal to or higher than the first set temperature.
And the ambient temperature detected by the ambient temperature sensor
Based on the engine load detected by the load sensor
The above water amount change is performed to stop the water pumping or to make the pumping amount variable.
Fuel injection apparatus is provided for a diesel engine, characterized in that a water quantity control means for controlling the means.
Preferably, the water amount control means includes the atmospheric temperature sensor.
The atmospheric temperature detected by the second predetermined temperature
Is lower than the temperature, the ambient temperature is the second set temperature.
Pumping water from higher engine load compared to above
It is desirable to control the water amount changing means in order to start
No.

[0007]

[Function] The water amount control means determines the engine temperature detection value in advance.
When the temperature is lower than the first set temperature, the water amount changing means is controlled.
Control the engine to stop the pumping of water.
Improves low-temperature startability during operation, and after low-temperature start or warm-up operation
Reduces white smoke emission at the time. In addition, the water flow control means
When the engine temperature detection value is above the first set temperature, the atmosphere
Water volume change based on temperature detected value and engine load detected value
Control the means to stop the pumping of water or make the pumping amount variable.
More preferably (invention of claim 2), detection of atmospheric temperature
If the value is lower than the second predetermined temperature,
Higher than when the detected air temperature value is equal to or higher than the second set temperature
By starting the pumping of water from a heavy engine load
To set an appropriate amount of water according to the ambient temperature and engine load.
Configurable.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a specific configuration of a fuel injection device for a diesel engine of the present invention. In FIG.
Indicates a fuel injection nozzle that is attached to each cylinder of a cylinder head (not shown) of a 4-cycle water injection diesel engine and injects mixed fuel and water into the combustion chamber.

More specifically, a large-diameter spring housing chamber 3 and a small-diameter rod hole 4 are continuously formed vertically on the center line of the nozzle holder 2 of the fuel injection nozzle 1. That is, the spring housing chamber 3 is open on the upper surface of the nozzle holder 2, and the rod hole 4 is open on the lower surface of the nozzle holder 2. A push rod 6 formed in a columnar shape and integrally provided with a disk-shaped spring seat 5 at the upper part thereof is slidably fitted into the rod hole 4 from the spring housing chamber 3 side. The adjusting screw 8 is inserted and screwed into the open end of the spring accommodating chamber 3 while the spring seat 5 is inserted.
A pusher spring 7 is interposed between the adjusting screw 8 and the adjusting screw 8 to urge the push rod 6 downward in the figure. The urging force of the pusher spring 7 can be adjusted by rotating the adjusting screw 8. Further, on the upper part of the nozzle holder 2, connection ends 9 and 10 for connecting the water pipe 30 and the fuel pipe 31 are provided.
Each is formed to protrude.

Next, the nozzle 11 formed in a substantially conical shape is provided with two disc-shaped cavities at its lower part, that is, a water reservoir 12 and a fuel reservoir 13 in two upper and lower layers. The fuel reservoir 13 penetrates the water reservoir 12 from the upper surface of the nozzle 11.
A guide hole 14 is formed. The guide hole 14 is formed to have a larger diameter than the rod hole 4 of the nozzle holder 2, and the nozzle needle 1 is provided in the guide hole 14.
5 is slidably and liquid-tightly inserted from above. The lower end portion of the nozzle needle 15 is formed in a conical shape, while the upper end portion is formed with a cylindrical protruding end 16 that can be inserted into the rod hole 4. At the lower end of the nozzle 11, a projection 17 having a substantially hemispherical tip is formed to protrude. At the tip of the projection 17, a plurality of injection holes 18 for injecting fuel and water into the combustion chamber at a required angle are formed. Have been. In addition, each spout 18
Communicate with the communication holes 19 formed in the projections 17, respectively.
The communication hole 19 opens in the fuel reservoir 13.

The nozzle 11 is fitted to a retaining nut 20, the retaining nut 20 is screwed to the nozzle holder 2, and the nozzle 11 is mounted to the nozzle holder 2 in a liquid-tight manner. Here, while the upper surface of the nozzle 11 and the lower surface of the nozzle holder 2 are in close contact with each other, the protruding end 16 of the nozzle needle 15 is inserted into the rod hole 4 to abut the push rod 6, and the nozzle needle 15 is 7 is always urged downward. As a result, the conical portion 14a of the nozzle needle 15 is
The fuel injection nozzle 1 is brought into contact with the open end 19a of the above to close the fuel injection nozzle 1. Further, the injection port 18 of the nozzle 11 is inserted through an opening 21 formed at the lower end of the retaining nut 20 and protrudes into the combustion chamber.

Further, the fuel reservoir 13 of the nozzle 11 and the connection end 10 of the nozzle holder 2 are communicated with each other by a feed hole 22 formed continuously with the nozzle 11 and the nozzle holder 2. Penetrates. In addition, the puddle 12 of the nozzle 11 and the nozzle holder 2
Is connected to the nozzle 11 and the nozzle holder 2 by a feed hole 23 continuously formed in the nozzle 11, and the feed hole 23 allows a water flow only from the connection end 9 to the pool 12. A valve 24 is interposed.

Next, connection ends 9 and 10 of the fuel injection nozzle 1
A water pump 40 and a fuel pump 70 are connected to each of them via a water pipe 30 and a fuel pipe 31, respectively. First, as shown in FIG. 2, the water pump 40 is configured by a so-called row type displacement pump, and a camshaft 42 interlocking with a crankshaft (not shown) is provided below a pump housing 41 via a bearing 43. The cam shaft 42 is rotatably supported, and a cam 44 is formed integrally with the cam shaft 42. Above the cam 44, the pump housing 41
A tabet 45 is slidably inserted into the tabet 45, and a tabet roller 46 for rolling the cam surface of the cam 44 is rotatably supported on the tabet 45. Tabet 4
A plunger 47 is fixed to the upper end of the plunger 5, and the plunger 47 reciprocates up and down integrally with the tabet 45 by the rotation of the cam 44. A plunger spring 50 is interposed between a lower spring seat 48 formed below the plunger 47 and an upper spring seat 49 fixed to the pump housing 41, and the plunger 47 is constantly urged downward by the plunger spring 50. Have been. The upper part of the plunger 47 is slidably and vertically slidably and vertically inserted into a substantially cylindrical control sleeve 51, and the upper part of the control sleeve 51 is rotatably inserted into the pump housing 41. ing. A pinion gear 52 is formed on the outer peripheral surface of the control sleeve 51, and the pinion gear 52 meshes with a rack 53 slidably inserted in the pump housing 41. For this reason, the control sleeve 51 is
Is driven by the pump housing 41 and the plunger 47 to be rotatable. The space above the plunger 47 in the control sleeve 51 is
Are formed.

A spiral groove, that is, a control groove 54 is formed on the outer peripheral surface of the upper end of the plunger 47, while feed holes 55, 55 are formed in the side wall of the control sleeve 51. The inner open ends of 55 and 55 are substantially flush with the upper end surface of the plunger 47 when the plunger 47 is at the bottom dead center. The pump housing 41 has a control sleeve 5.
1, a water reservoir 56 is formed, and the water reservoir 56 has open outer ends of feed holes 55, 55.
6 communicates with a water supply port 68. That is, the water supply port 68 and the feed holes 55, 55 are always in communication via the water reservoir 56 irrespective of the rotational position of the control sleeve 51.

Next, a delivery valve holder 57 is fixed to the upper end of the pump housing 41 in a liquid-tight manner, and a valve housing chamber 58 is provided inside the delivery valve holder 57. The valve housing chamber 58 houses a delivery valve 60 and a delivery valve spring 59. The valve accommodating chamber 58 and the cylinder chamber 66 are communicated with each other by a valve guide hole 67, and a guide portion 61 of a delivery valve 60 is slidably fitted in the valve guide hole 67. Further, at the opening end of the valve guide hole 67 on the valve accommodating chamber 58 side, the conical valve portion 6 of the delivery valve 60 is provided.
2 is urged by the delivery valve spring 59 to come into contact with it, and the delivery valve 60 is closed. The valve chamber 58 and the cylinder chamber 66 are also communicated by a bypass 63, and a check valve 64 that allows only water flow from the valve chamber 58 to the cylinder 66 is interposed in the bypass 63. . The valve housing chamber 58 communicates with the discharge port 65 of the water pump 40. When the delivery valve 60 opens, the cylinder chamber 66 and the discharge port 65 communicate with each other.

The water pump 40 has a rack actuator (water injection amount changing means) 8 as shown in FIG.
0 is attached. The rack actuator 80 is electrically connected to a controller (control means) 90 and is controlled by an electric signal of the controller 90, and the water pump 40
Can be moved to a required position. That is, the rack actuator 80 is controlled by the controller 90 to rotate the plunger 51 through the rack 53 and the pinion gear 52, as described later, to reduce the discharge amount of the water pump 40 from zero to at least the maximum engine load Lmax. It is possible to continuously change the injection amount up to the hour.

On the other hand, as shown in FIG. 3, the fuel pump 70 is constituted by an in-line displacement pump similar to the water pump 40. Therefore, although detailed description is omitted here, the cam 71 is formed in a shape different from the cam 44 as described later. The fuel injection nozzle 1, the water pump 40, and the fuel pump 70 are appropriately subjected to rust prevention such as adoption of a corrosion-resistant material and plating to prevent water corrosion.

As shown in FIG. 1, a rack actuator 81 is mounted on the fuel pump 70. The rack actuator 81 is also electrically connected to the controller 90 and is controlled by an electric signal of the controller 90 to reduce the discharge amount of the fuel pump 70 from zero to at least the maximum engine load as in the case of the rack actuator 80 of the water pump 40. It is possible to continuously change the discharge amount to the total amount of the fuel injection amount and the water injection amount at Lmax.

The controller 90 also includes an engine speed sensor 91 for detecting the engine speed, an engine load sensor 92 for detecting the engine load, an atmospheric temperature sensor 93 for detecting the ambient temperature, and the temperature of the engine coolant. , The engine speed Ne detected by the engine speed sensor 91, the engine load L detected by the engine load sensor 92, the atmospheric temperature Ta detected by the atmospheric temperature sensor 93, and the cooling water. The engine cooling water temperature Tw and the like detected by the temperature sensor 94 are input to the controller 90. That is, the engine speed sensor 91, the engine load sensor 92, the atmospheric temperature sensor 93, and the coolant temperature sensor 94 constitute an engine operating state detecting means, and the controller 90 controls the engine based on the operating state of the engine detected by these sensors. Water pump 4
0 of the water pump 40
Discharge amount, that is, the water injection amount injected from the fuel injection nozzle 1 is changed. Here, the engine load sensor 92 includes, for example, an accelerator opening sensor that detects the amount of depression of the accelerator.

Next, the procedure of water injection amount control executed by the controller 90 will be described with reference to FIGS. 4 to 11. First, the controller 90 first determines the engine speed Ne detected by the engine speed sensor 91, the engine load L detected by the engine load sensor 92, the atmospheric temperature Ta detected by the atmospheric temperature sensor 93, and the cooling water temperature sensor 9.
4 reads the detected engine coolant temperature Tw (step S10).

Next, the controller 90 determines whether or not the engine coolant temperature Tw detected by the coolant temperature sensor 94 is lower than a predetermined set temperature Two (step S2).
0). The predetermined set temperature Two means that even when water injection is performed when the engine coolant temperature Tw is equal to or higher than this temperature, ignition of the fuel mixture at the time of engine start is performed quickly, and the engine startability is improved. A temperature at which the white smoke is not emitted after the engine is started.

The determination result of step S20 is affirmative (Yes
In the case of s), the water injection amount Qw is set to zero (step S80). That is, in this case, only the fuel is injected from the fuel injection nozzle 1 during the fuel injection. If the result of the determination in step S20 is negative (No), it is next determined whether or not the atmospheric temperature Ta detected by the atmospheric temperature sensor 93 exceeds a predetermined set temperature Tao (step S30). Here, the predetermined set temperature Tao means that when the atmospheric temperature Ta is equal to or lower than this temperature, the intake air density with respect to the fuel becomes sufficiently high, and the emission of soot is kept at a low level without performing water injection. The temperature at which it sags.

If the result of the determination in step S30 is affirmative, then referring to FIG. 5, the operating state of the engine determined by the engine speed Ne and the engine load L detected in step S10 is shown in FIG. It is determined whether or not it is in the indicated water injection region (step S40). here,
FIG. 5 shows the case where the atmospheric temperature Ta exceeds the predetermined set temperature Tao, that is, the engine speed N during normal operation.
FIG. 4 is a characteristic diagram showing a relationship between the engine load L and the water injection region, and when the engine load L is equal to or greater than a predetermined set load La provided substantially in the middle between zero and the maximum load Lmax, the engine speed Ne is reduced. Regardless, it specifies that water injection be performed.

On the other hand, if the result of the determination in step S30 is negative, then referring to FIG. 6, the operating state of the engine determined by the engine speed Ne and the engine load L detected in step S10 is shown in FIG. It is determined whether or not it is in the indicated water injection area (step S50). Here, FIG. 6 is a characteristic diagram showing the relationship between the engine speed Ne, the engine load L, and the water injection region when the atmospheric temperature Ta is equal to or lower than the predetermined set temperature Tao, that is, during low temperature operation.
When the engine load L is equal to or greater than a predetermined set load Lb provided substantially in the middle between the maximum load Lmax and the predetermined set load La during the normal operation, water injection is performed regardless of the engine speed Ne. doing.

If the result of the determination in step S40 is negative,
Alternatively, if the result of the determination in step S50 is negative, the water injection amount Qw is set to zero (step S80). Then, at the time of fuel injection, only the fuel is used as shown in FIG.
, The fuel is injected by the fuel injection amount Qf obtained corresponding to the engine load L. When the determination result of step S40 is affirmative, for example, the water injection amount Qw is calculated with reference to FIG. 7 (step S60), and at the same time, the fuel injection amount Qf is also obtained. Here, FIG. 7 shows the relationship between the engine load L and the fuel injection amount Qf and the relationship between the engine load L and the water injection amount Qw when the atmospheric temperature Ta exceeds the predetermined set temperature Tao, that is, during normal operation. FIG. 5 is a characteristic diagram showing an engine speed N as an example.
The case where e is at a constant value Neo is shown. That is, the relationship between the engine load L and the fuel injection amount Qf and the relationship between the engine load L and the water injection amount Qw are appropriately set according to the engine speed Ne. According to FIG. 7, when the engine load L changes from zero to the maximum load Lmax., The fuel injection amount Qf is changed from the fuel injection amount Qf1 during idling to the maximum injection amount Qf2 during normal operation.
While being by Uni settings that increase substantially as a linear function,
Water injection amount Qw when the engine load L is changed to a maximum load Lmax. From La as described above, since the maximum injection amount Qw2 L by Uni set substantially you increase as a linear function up to during normal operation Qw1 I have.

If the result of the determination in step S50 is affirmative, for example, referring to FIG. 8, the water injection amount Qw is calculated (step S70), and at the same time, the fuel injection amount Qf is also obtained. FIG. 8 shows the relationship between the engine load L and the fuel injection amount Qf and the relationship between the engine load L and the water injection amount Qw when the atmospheric temperature Ta is equal to or lower than the predetermined set temperature Tao, that is, during low-temperature operation. FIG. 4 is a characteristic diagram illustrating a case where the engine speed Ne is at a constant value Neo as an example. Also in this case, the relationship between the engine load L and the fuel injection amount Qf and the relationship between the engine load L and the water injection amount Qw are appropriately set according to the engine speed Ne. According to FIG. 8, when the engine load L changes from zero to the maximum load Lmax., The fuel injection amount Qf
While the fuel injection amount Qf3 during idling is the maximum injection amount Qf4 substantially increased to that by <br/> urchin set as a linear function of L to the at a low temperature operation, the water injection amount Qw is the engine load L is The constant value Qw3 is set from the above-mentioned Lb to the maximum load Lmax.

Then, the controller 90 determines in step S
Water injection amount Q calculated by any of 60 to S80
w based on the rack actuator 80 of the water pump 40
To slide the control rack 53 of the water pump 40 so that the water injection amount Qw is discharged from the water pump 40 (step S90). Then, when the control rack 53 is slid, the water pump 40 operates as follows. That is, the control rack 53 rotates the control sleeve 51 via the pinion gear 52, and when the control sleeve 51 rotates, the positional relationship between the control sleeve 51 and the plunger 47 changes, and the feed holes 55, The amount of stroke of the plunger 47 until the inside opening end of the groove 55 communicates with the groove of the control groove 54 changes. In addition, the feed hole 55 of the control sleeve 51,
The reason why the water injection amount Q _W changes when the stroke amount of the plunger 47 until the inner opening end of 55 and the groove of the control groove 54 communicate with each other will be described later. As a result, the routine for controlling the water injection amount ends, and the program returns.

Further, the controller 90 controls the rack actuator 81 so that the fuel of the injection amount Qf is injected from the fuel injection nozzle 1, and moves the control rack 74 of the fuel pump 70. Next, the fuel injection amount Q
In the present fuel injection device in which f and the water injection amount Qw are controlled by the controller 90 as described above, the fuel injection and the water injection are performed as follows.

First, FIG. 9 shows the state of filling of fuel and water in the fuel injection nozzle 1 immediately after fuel injection. At this time, the nozzle needle 15 of the fuel injection nozzle 1 is urged by the pusher spring 7 and abuts the opening end of the communication hole 19 formed in the fuel reservoir 13, so that the fuel injection nozzle 1 is closed. Then, the fuel fills the fuel reservoir 13 and the feed hole 22, and the water fills the water reservoir 12 and the feed hole 23.
Is full. The check valve 24 is closed.

The plunger 47 of the water pump 40
Is at the bottom dead center due to the operation of the cam 44 immediately after the fuel injection. At this time, water is supplied to the cylinder chamber 66 through the water supply port 68, the water pool 56, and the feed holes 55, 55. Then, during the expansion stroke after the fuel injection is completed and the nozzle needle 15 of the fuel injection nozzle 1 is completely closed, the cam shaft 42 rotates the cam 44 in conjunction with a crankshaft (not shown), and The plunger 47 is pushed upward against the urging force of the plunger spring 50 via the lever 45. Then, the plunger 47 closes the inner open ends of the feed holes 55, 55, the feed holes 55, 55 and the cylinder chamber 66 are shut off, and the water in the cylinder chamber 66 is removed by the upward movement of the plunger 47. Pressurized gradually. When the water pressure in the cylinder chamber 66 is increased to a required pressure, the delivery valve 60
The valve opens against the urging force of No. 9. At this time, since the check valve 64 is closed, the water in the cylinder chamber 66 is discharged from the discharge port 65. Here, the discharge pressure of the water pump 40 depends on the check valve 24 of the fuel injection nozzle 1 and the check valve 72 of the fuel pump 70.
And higher than the valve opening pressure of the nozzle needle 15 of the fuel injection nozzle 1, and the delivery valve spring 59 is attached so that such a discharge pressure is obtained. The power is being adjusted.

The plunger 73 of the fuel pump 70 moves rapidly to the top dead center during fuel injection, but stops at the bottom dead center except during fuel injection. Such a plunger 7
The cam 71 is formed so that the operation of No. 3 is obtained. When water starts to be discharged from the water pump 40 as described above, the check valve 24 of the fuel injection nozzle 1 and the check valve 72 of the fuel pump 70 are opened, while the nozzle needle of the fuel injection nozzle 1 is opened. No. 15 is still closed. Further, since the plunger 73 of the fuel pump 70 as described above in the bottom dead center, the fuel pressure in the feed hole 22 is low Ri by water pressure, Thus, water through the check valve 24 and water reservoir 12 To enter the fuel side feed hole 22. And the control groove 5 of the water pump 40
When the spiral groove of No. 4 has risen to the inner open end of the feed holes 55, 55, the cylinder chamber 66 and the feed holes 55, 55 communicate with each other via the control groove 54, and the water pressure in the cylinder chamber 66 becomes water. The pressure drops to the water pressure of the reservoir 56, and the delivery valve 60 is closed by the urging force of the delivery valve spring 59. Thereafter, the communication state between the cylinder chamber 66 and the feed holes 55, 55 is maintained until the plunger 47 reaches the top dead center, and the water pressure in the cylinder chamber 66 is maintained at the same pressure as the water pressure in the water sump 56.

As described above, the water pump 40 is connected to the plunger 4
7 from the bottom dead center position to the position where the groove of the control groove 54 reaches the inner open end of the feed holes 55, 55, that is, step S60.
Or water only computed water injection amount Q _W will be discharged in step S70. Here, when the water injection amount Q _W is zero, the inner opening ends of the feed holes 55, 55 of the control sleeve 51 and the control groove 54.
Are always in communication, and the delivery valve 60 remains closed by the urging force of the delivery valve spring 59 even when the cam 42 pushes the plunger 47 upward. Therefore, no water is discharged from the water pump 40.

[0033] Now, the water only injection amount Q _W finishes are injected as shown in Figure 5 into the feed hole 22, the discharge pressure of the water pump 40 is lowered check valve 24 of the fuel injection nozzle 1 is closed Backflow of valve water is prohibited and the fuel pump 7
The zero check valve 72 is also closed. Then, the water only injection amount Q _W until the next fuel injection is accommodated in the feed hole 22 of the fuel injection nozzle 1. In addition, the above water pump 40
Is started during the expansion stroke after the nozzle needle 15 of the fuel injection nozzle 1 is closed, and continues through the exhaust stroke and the intake stroke until the compression stroke before the nozzle needle 15 opens. You. The cam 44 is formed so that the water is discharged by the water pump 40 in such a gradual manner, so that the water pressure instantaneously increases and the nozzle needle 15 of the fuel injection nozzle 1 opens. Has been prevented.

Next, at the time of fuel injection, the fuel pump 70 operates in the same manner as the water pump 40 to discharge a predetermined amount Qt of fuel. Then, the nozzle needle 15 of the fuel injection nozzle 1
Due to the fuel pressure applied to the conical portion 14a, the nozzle needle 15 opens against the urging force of the pusher spring 7,
As shown in FIG. 6, first, the fuel Qfp flowing into the fuel reservoir 13 of the fuel injection nozzle 1 is injected.
The water Qw injected into the feed hole 22 is injected, and finally, the fuel Qfs, which is filled on the fuel pump 70 side, from the water Qw in the feed hole 22 is injected to complete the fuel injection. At this time, the above-mentioned Qt, Qf, Qf
The following equations (1), (2) and (3) hold for p, Qw and Qfs.

[0035] _{Qt = Qf + Q W ··· (} 1) Qf = Qfp + Qfs ··· (2) Qt ≧ Qfp + Qw ··· (3) where, Qf is the fuel actually injected from the fuel injection nozzle 1 This is the injection amount. Further, Qfp is always constant regardless of the water injection amount Qw. When the water injection amount Qw is changed, it is necessary to change the discharge amount Qt of the fuel pump 70, and the discharge amount Qt must be equal to or more than the sum of Qfp and Qw. This is to ensure that the fuel is injected and that no water remains in the fuel reservoir 13.

When one injection of fuel and water is completed as described above, the filling state of fuel and water in the fuel injection nozzle 1 returns to the above-mentioned state of FIG. As described above, in the present fuel injection device, water injection is prohibited at the time of low-temperature start-up, so that ignitability of the fuel-air mixture is kept good and white smoke is not discharged after the start-up. Also, since the combustion temperature is low and the fuel density is low, N
Water injection is not performed at a low load when both the emission concentrations of Ox and soot are reduced, and water injection is performed only at a high load where truly water injection is desired. It is used to reduce NOx and soot.

The fuel injection device for a diesel engine according to the present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the configurations of the fuel injection nozzle 1, the water pump 40, the fuel pump 70, the rack actuators 80, 81, and the like are not limited to those described above, and may be changed as appropriate. For example, the water pump 40
Need not necessarily be a column type pump of the same type as the fuel pump 70, and need not be a column type displacement pump. Further, the water pump 40 does not have to be a positive displacement pump. For example, the water pump may be a constant pressure type water pump 120, and as shown in FIG. 12, control may be performed between the water pump 120 and the fuel injection nozzle 1. Valve (water injection amount changing means) 1
21 may be provided. This control valve 12
1 is, for example, the built-in valve controlled by the controller 90 is opened for an energizing time, and the amount of water supplied to the fuel injection nozzle 1 from the water pump 120 is reduced from zero to at least the injection amount at the time of the maximum engine load Lmax. May be changed continuously.

In the above-described embodiment, the water injection region defined by FIG. 5 or FIG. 6 may be set so as to vary not only with the engine load L but also with the engine speed Ne. The controller 90 in the above-described embodiment is not necessarily a controller that simultaneously controls the water injection amount and the fuel injection amount as described above, and may be a controller that controls only the water injection amount. Further, it may be a controller that controls all the operations of the engine together with the water injection amount.

Further, the fuel injection amounts Qf1 and Qf3 or Qf2 and Qf shown in FIGS. 7 and 8 in the above-described embodiment.
f4 may be different values or the same value. Further, the water injection amount Qw3 in FIG. 8 may be a value different from the water injection amount Qw1 or Qw2 in FIG. 7, or may be the same value as one of them. The fuel injection device can also be applied to a two-cycle diesel engine.

[0040]

As described in detail above, in the fuel injection system for a diesel engine according to the present invention, the water amount control means is provided.
The stage is the first set temperature at which the engine temperature detection value is predetermined.
If the temperature is lower than the temperature, control the water amount changing means to stop pumping water.
And the engine temperature detection value is equal to or higher than the first set temperature.
Time, based on the detected atmospheric temperature and the detected engine load.
Control the water volume change means to stop the water pumping or pump
Is made variable. Thus, when the operating state of the engine truly water injection is desired, for example, it is possible to only perform water injection at high engine load such that the NOx and soot are particularly large amount of discharge, and water The water injection device can be operated efficiently to effectively suppress the emission of NOx and soot, but the ignitability of the fuel mixture is reduced during the operating state of the engine where adverse effects due to water injection occur. Cold start , low engine temperature after start or low atmosphere
Since the water injection can be prohibited at the time of temperature or the like, there is an effect that the low temperature startability is improved and the emission of white smoke can be prevented.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a specific configuration of a fuel injection device for a diesel engine of the present invention.

FIG. 2 is a side sectional view showing a configuration of a main part of a water pump 40 in FIG.

FIG. 3 is a side sectional view showing a configuration of a main part of a fuel pump 70 in FIG. 1;

FIG. 4 is a flowchart showing a procedure of water injection amount control executed by a controller 90 in FIG. 1;

FIG. 5 is a characteristic diagram showing a relationship between an engine speed Ne, an engine load L, and a water injection region during normal operation.

FIG. 6 is a characteristic diagram showing a relationship among an engine speed Ne, an engine load L, and a water injection region during low temperature operation.

FIG. 7 is a characteristic diagram showing the relationship between the engine load L and the fuel injection amount Qf and the relationship between the engine load L and the water injection amount Qw during normal operation.

FIG. 8 is a characteristic diagram showing the relationship between the engine load L and the fuel injection amount Qf and the relationship between the engine load L and the water injection amount Qw during low-temperature operation.

9 is a side sectional view showing a filling state of fuel and water in the fuel injection nozzle 1 in FIG. 1 immediately after fuel injection.

FIG. 10 is a side sectional view showing a state of filling fuel and water immediately before fuel injection of a fuel injection nozzle 1 in FIG. 1;

11 is a diagram showing a state where fuel is injected from a fuel injection nozzle 1 in FIG.
FIG. 6 is a characteristic diagram showing a relationship between an injection amount of fuel and water per unit time and an elapsed time.

FIG. 12 is a block diagram showing another configuration of the diesel engine fuel injection device of the present invention.

[Explanation of symbols]

 Reference Signs List 1 fuel injection nozzle 40 water pump 53 control rack 70 fuel pump 74 control rack 80 rack actuator (water injection amount changing means) 81 rack actuator 90 controller (control means) 91 engine speed sensor (operating state detecting means) 92 engine load sensor (Operating state detecting means) 93 Atmospheric temperature (Operating state detecting means) 94 Cooling water temperature (Operating state detecting means) 120 Water pump 121 Control valve (Water injection amount changing means)

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masayoshi Nakajima 2-5-1 Marunouchi, Chiyoda-ku, Tokyo Inside Mitsubishi Heavy Industries, Ltd. (56) References JP-A-62-27961 (JP, A) -107760 (JP, U) Japanese Patent Sho 56-47378 (JP, B2)

Claims (2)

(57) [Claims] And 1. A fuel pump for pumping fuel, and water pump for pumping water, and fuel injection nozzle for injecting fuel and water, which is pumped by said fuel pump and the water pump to the combustion chamber of the engine, the Fuel that changes the amount of fuel pumped from the fuel pump
Water amount change means and water amount change for changing the amount of water pumped from the water pump
Means and the fuel amount changing means based on the operating state of the engine
A fuel amount control means for controlling the temperature of the engine, an engine temperature sensor for detecting the temperature of the engine, an atmospheric temperature sensor for detecting the atmospheric temperature, an engine load sensor for detecting the load on the engine, and an engine temperature sensor. Engine temperature
Pumping water when the temperature is lower than the first preset temperature
While controlling the water amount changing means to stop,
When the engine temperature is above the first set temperature, the ambient temperature
The atmospheric temperature detected by the sensor and the load sensor
Stop pumping water based on the detected engine load
Alternatively, the water amount changing means is controlled so as to make the pumping amount variable.
The fuel injection system of a diesel engine, characterized in that a water quantity control means that. 2. The water amount control means is configured to detect the ambient temperature sensor.
The second setting in which the atmospheric temperature detected by the service is predetermined
When the temperature is lower than the temperature, the ambient temperature is the second set temperature.
Higher engine load water pressure than above
Controlling the water amount changing means to start the water supply
Fuel injection for a diesel engine according to claim 1,
apparatus.