JP2011252411A - Diesel engine and method of controlling the same - Google Patents

Abstract

A diesel engine capable of reliably igniting while suppressing carbon dioxide emission is provided.
A diesel engine includes a first gas fuel injection valve that injects gas fuel into a cylinder chamber, an ignition chamber that communicates with the cylinder chamber, and an ignition fuel that is injected into the ignition chamber. A pilot valve 60 and a second gas fuel injection valve 70 that injects gas fuel into the ignition chamber 80 are provided.
[Selection] Figure 1

Description

  The present invention relates to a diesel engine and a diesel engine control method.

  In order to contribute to the prevention of global warming, diesel engines with good startability and high thermal efficiency are widely used in many fields. In such a diesel engine, the amount of carbon dioxide emission is reduced by about 20% due to the difference in fuel composition by changing the fuel from heavy oil fuel to gas fuel.

  Here, in the diesel engine using gas fuel, there exists a problem that unburned hydrocarbon (HC) arises in a combustion process. Such a problem is that the gas fuel is taken into the cylinder in the piston intake process and mixed with the air in the cylinder, and the taken gas fuel is ignited by being compressed, so that the temperature hardly rises near the side wall of the cylinder. This is due to the fact that the gas fuel is likely to be unburned.

A gas injection diesel engine (GIDE) is known as a diesel engine capable of reducing the amount of unburned HC emissions (see Patent Document 1).
In GIDE, air is taken into the cylinder in the piston intake process, the air is compressed to the vicinity of the top dead center of the piston, and then high-pressure gas fuel is injected into the cylinder to increase the combustion efficiency of the gas fuel. This prevents the generation of unburned HC.

JP 2005-147046 A

Gas fuel has a high natural ignition temperature, and it is difficult to achieve stable ignition in GIDE. Use an external heat source such as a glow plug for ignition, or introduce ignition fuel such as light oil or heavy oil into the cylinder. In order to improve the certainty of ignition, a technique has been devised.
However, when an external heat source is used, an external power source that supplies electric power to the external heat source is required, and these controls are required, which complicates the system. In addition, when an ignition fuel such as light oil or heavy oil is introduced into the cylinder, the amount of carbon dioxide emission increases according to the amount of ignition fuel used.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a diesel engine and a diesel engine control method capable of reliably igniting while suppressing carbon dioxide emission.

  In order to solve the above problems, a diesel engine according to the present invention is a diesel engine including a cylinder having a cylinder chamber and a piston that reciprocates in the cylinder chamber, and first injects gas fuel into the cylinder chamber. A gas fuel injection valve, an ignition chamber communicating with the cylinder chamber, a pilot valve for injecting ignition fuel into the ignition chamber, and a second gas fuel injection valve for injecting gas fuel into the ignition chamber, It is characterized by providing.

  According to this configuration, the pilot valve self-ignites the ignition fuel in the ignition chamber by injecting the ignition fuel into the ignition chamber, and then the second gas fuel injection valve injects the gas fuel into the ignition chamber. The operation of burning the gas fuel in the cylinder chamber is enabled by injecting the flame into the cylinder chamber and then the first gas fuel injection valve injecting the gas fuel into the cylinder chamber, so that ignition can be ensured. . Further, since the ignition fuel is self-ignited not in the cylinder chamber but in the ignition chamber, the amount of ignition fuel used can be reduced and the amount of carbon dioxide emitted can be suppressed.

  In the diesel engine control method of the present invention, the diesel engine according to claim 1 is controlled by a control unit that controls opening / closing of the first gas fuel injection valve, the pilot valve, and the second gas fuel injection valve. A method for controlling the diesel engine, wherein the control unit self-ignites the ignition fuel in the ignition chamber by opening the pilot valve and injecting the ignition fuel into the ignition chamber; The control unit opens the second gas fuel injection valve and injects the gas fuel into the ignition chamber, thereby amplifying the flame caused by the self-ignition of the ignition fuel and injecting it into the cylinder chamber And the control unit opens the first gas fuel injection valve to inject the gas fuel into the cylinder chamber, whereby the gas in the cylinder chamber is injected. Characterized in that it comprises the steps of: combusting a fee.

  ADVANTAGE OF THE INVENTION According to this invention, the diesel engine and diesel engine control method which can perform reliable ignition, suppressing the discharge amount of a carbon dioxide can be provided.

1 is a schematic cross-sectional view showing a diesel engine according to an embodiment of the present invention. 1 is a schematic cross-sectional view showing a diesel engine according to an embodiment of the present invention. 1 is a schematic cross-sectional view showing a diesel engine according to an embodiment of the present invention. It is a figure which shows the valve opening timing and valve opening period of the 1st gas fuel injection valve which concerns on embodiment of this invention, a pilot valve, and a 2nd gas fuel injection valve.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings as appropriate. Similar parts are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIG. 1, a diesel engine 1 according to an embodiment of the present invention is a gas injection diesel engine (GIDE) that injects high-pressure gas fuel into a cylinder, and includes a cylinder head 10 and a cylinder liner 20. A piston 30, a connecting rod 40, and an injection valve unit VU.

  The cylinder head 10 includes a gas fuel passage 11 through which high-pressure gas fuel flows, an ignition fuel passage 12 through which high-pressure ignition fuel (for example, liquid fuel such as light oil and heavy oil) flows, and high-pressure seal oil. And a drain passage 14 through which seal oil and ignition fuel circulate and are discharged to the outside.

  The cylinder liner 20 is a member having a cylindrical shape, and accommodates the piston 30 and the connecting rod 40 therein, and its upper opening is closed by the cylinder head 10 and the injection valve unit VU.

  The piston 30 is a member having a disk shape accommodated in the cylinder liner 20, and the outer diameter thereof is substantially the same as the inner diameter of the cylinder liner 20. The cylinder head 10, the cylinder liner 20, and the injection valve unit VU constitute a cylinder, and a space surrounded by the cylinder head 10, the cylinder liner 20, the piston 30, and the injection valve unit VU is a cylinder chamber CC.

  The connecting rod 40 is connected to the piston 30 and reciprocates the piston 30.

  The injection valve unit VU is a unit mounted in the hole of the cylinder head 10, and includes a first gas fuel injection valve 50, a pilot valve 60, a second gas fuel injection valve 70, an ignition chamber 80, Is integrally provided. The first gas fuel injection valve 50, the pilot valve 60, and the second gas fuel injection valve 70 are controlled to be opened and closed by a control unit 100 including a CPU (Central Processing Unit).

  The first gas fuel injection valve 50 is a normally closed electromagnetic valve. In a normal state, the valve body 51 is seated on the valve seat 52, and the flow path 53 and the injection hole 54 communicated with the gas fuel flow path 11. Is shut off (valve closed). When the first gas fuel injection valve 50 is energized in a coil (not shown) by a valve opening signal output from the control unit 100, a movable core (not shown) connected to the valve body 51 by electromagnetic induction action. ) Moves upward in the drawing, the valve body 51 is separated from the valve seat 52, and the flow path 53 communicating with the gas fuel flow path 11 and the injection hole 54 are in a state in which gas can flow (valve open state). The gas fuel introduced from the gas fuel channel 11 into the channel 53 is injected into the cylinder chamber CC through the injection hole 54.

  The pilot valve 60 is a normally closed electromagnetic valve, and in a normal state, the flow path 61 communicating with the ignition fuel flow path 12 and the ignition chamber 80 are blocked (valve closed state). When the pilot valve 60 is energized to a coil (not shown) by a valve opening signal output from the control unit 100, the flow path 61 communicating with the ignition fuel flow path 12 and the ignition chamber 80 can flow in liquid. Then, the ignition fuel introduced into the flow path 61 communicating with the ignition fuel flow path 12 is injected into the ignition chamber 80.

  The second gas fuel injection valve 70 is a normally closed electromagnetic valve. In a normal state, the valve element 71 is seated on the valve seat 72, and the flow path 73 and the ignition chamber 80 communicating with the flow path 53 are defined as follows. Shut off (valve closed). When the second gas fuel injection valve 70 is energized to a coil (not shown) by a valve opening signal output from the control unit 100, a movable core (not shown) connected to the valve body 71 by electromagnetic induction action. ) Moves upward in the figure, the valve body 71 is separated from the valve seat 72, and the gas flow is established between the flow path 73 communicating with the flow path 53 and the ignition chamber 80 (the valve open state). Gas fuel introduced into the flow path 73 from the fuel flow path 11 via the flow path 53 is injected into the ignition chamber 80.

  The ignition chamber 80 is provided on the downstream side of the pilot valve 60 and the second gas fuel injection valve 70, and the volume thereof is smaller than the volume of the cylinder chamber CC when the piston 30 is located at the top dead center. The ignition chamber 80 communicates with the cylinder chamber CC via the injection hole 81.

  The injection valve unit VU includes flow paths VU1 and VU2, and the seal oil supplied from the seal oil flow path 13 is supplied to the first gas fuel injection valve 50 and the second gas via the flow path VU1. It is supplied to the fuel injection valve 70. Further, seal oil (leakage oil) leaked from the first gas fuel injection valve 50, the pilot valve 60, and the second gas fuel injection valve is discharged to the outside of the diesel engine 1 through the flow path VU2 and the drain passage 14. Is done. Such seal oil is a fluid for sealing so that the gas fuel does not leak to the ignition fuel side, and the pressure of the seal oil is set higher than the pressure of the gas fuel.

<Operation example>
Subsequently, an operation example of the diesel engine 1 according to the embodiment of the present invention will be described with reference to FIGS. 1 to 4.

First, as shown in FIG. 1, the control unit 100 performs cranking based on a detection result output from a crank pulse sensor Sa that detects the position of a crankshaft (not shown) that is linked to the position of the piston 30. Recognizing that the piston 30 has been lifted by the movement of the connecting rod 40 that transmits the rotation of the shaft and has reached the vicinity of the top dead center, a valve opening signal is output to the pilot valve 60 (time in FIG. 4). t1). The pilot valve 60 is opened by a valve opening signal, and the ignition fuel introduced from the ignition fuel channel 12 into the channel 61 is injected into the ignition chamber 80.
The ignition fuel injected into the ignition chamber 80 is self-ignited by the air temperature in the ignition chamber 80 that has risen due to compression by the piston 30.

Subsequently, as shown in FIG. 2, the control unit 100 outputs a valve opening signal to the second gas fuel injection valve 70 after a first predetermined time has elapsed from time t1 (time t2 in FIG. 4). The second gas fuel injection valve 70 is opened by a valve opening signal, and injects the gas fuel introduced from the gas fuel flow path 11 through the flow path 53 into the flow path 73 to the ignition chamber 80.
The gas fuel injected into the ignition chamber 80 is ignited by the flame generated by the self-ignition of the ignition fuel, and the flame amplified by the ignition is injected into the cylinder chamber CC through the injection hole 81.
Subsequently, the control unit 100 stops outputting the valve opening signal to the pilot valve 60 after a second predetermined time has elapsed from time t1 (time t3 in FIG. 4), and closes the pilot valve 60.

Subsequently, as shown in FIG. 3, the control unit 100 outputs a valve opening signal to the first gas fuel injection valve 50 after a third predetermined time has elapsed from time t1 (time t4 in FIG. 4). The first gas fuel injection valve 50 is opened by a valve opening signal, and the gas fuel introduced from the gas fuel 11 into the flow path 53 is injected into the cylinder chamber CC.
The gas fuel injected into the cylinder chamber CC is ignited by the flame injected from the injection hole 81 and causes combustion. The piston 30 is pushed downward by the pressure in the cylinder chamber CC increased by the combustion.
Subsequently, the control unit 100 stops outputting the valve opening signal to the second gas fuel injection valve 70 after the fourth predetermined time has elapsed from time t1 (time t5 in FIG. 4), and the second gas fuel injection valve. 70 is closed.

  Subsequently, the control unit 100 stops outputting the valve opening signal to the first gas fuel injection valve 50 after the fifth predetermined time has elapsed from time t1 (time t6 in FIG. 4), and the first gas fuel injection valve. 50 is closed. Thereafter, the control unit 100 repeats the same operation when the piston 30 reaches near the top dead center.

The control unit 100 indicates the opening timing and opening period of the first gas fuel injection valve 50, the pilot valve 60, and the second gas fuel injection valve 70 described above, including the state quantity of the diesel engine 1 and the like. Can be changed based on the signal.
Crank pulse sensor signal: The control unit 100 acquires a crank pulse sensor signal that is a detection result of the crank pulse sensor Sa and converts the rotation speed (rotation speed). For example, when the rotation speed is large, each valve 50 , 60, 70 can be shortened.
Load signal: The control unit 100 displays a load signal (a signal based on a propeller load characteristic when the diesel engine 1 drives a propeller of a ship when the diesel engine 1 drives a propeller of a ship. And the valve opening timing and the valve opening period of each valve 50, 60, 70 can be changed based on the load.
Exhaust gas temperature signal: The control unit 100 acquires an exhaust gas temperature signal that is a detection result of a sensor (not shown) that detects the temperature of the exhaust gas from each cylinder chamber CC, and based on the exhaust gas temperature, the cylinder The valve opening timing and valve opening period of each valve 50, 60, 70 can be changed so as to eliminate the deviation for each chamber CC. Moreover, the control part 100 can monitor states, such as misfire and abnormal combustion, based on exhaust gas temperature, and can control each valve 50, 60, 70 according to this state.
Supply air temperature signal: The control unit 100 acquires a supply air temperature signal that is a detection result of a sensor (not shown) that detects the temperature of air taken into the cylinder chamber CC, and controls each valve based on the supply air temperature. A desired air-fuel ratio can be realized by changing the valve opening timing and valve opening period of 50, 60, and 70.
In-cylinder pressure signal: The control unit 100 acquires a cylinder pressure signal that is a detection result of a sensor (not shown) that detects the pressure in the cylinder chamber CC, and based on the maximum value (maximum pressure in the cylinder). The valve opening timing and the valve opening period of each valve 50, 60, 70 can be changed. For example, as the maximum pressure in the cylinder is large, increases the thermal efficiency, but increases the amount of the discharged the NO _X, since the life of the device becomes high stresses in the cylinder becomes shorter, the control unit 100, cylinder maximum pressure The valve opening timing and the valve opening period of each valve 50, 60, 70 are changed so that becomes an appropriate value. The control unit 100 can also detect knocking (abnormal combustion) unique to the gas fuel engine based on the cylinder pressure signal.
NO _X emission amount signal: The control unit 100 acquires a NO _X emission amount signal that is a detection result of a sensor (not shown) that detects the amount of NO _X discharged from the cylinder chamber CC, and the NO _X emission amount There when more than a predetermined value, it is possible to change the opening timing and opening period of each valve 50, 60, 70 as the discharge amount of the NO _X is reduced.
Emergency stop signal: The control unit 100 can stop the driving of the valves 50, 60, and 70 when an emergency stop signal is obtained by a user operation of a button or the like.
Note that the timing at which the first gas fuel injection valve 50 is opened varies depending on the signal described above, and therefore may be before top dead center (TDC in FIG. 4) or after top dead center. There is also.

  In the diesel engine 1 according to the embodiment of the present invention, the pilot valve 60 injects the ignition fuel into the ignition chamber 80 to cause the ignition fuel to self-ignite in the ignition chamber 80, and then the second gas fuel injection valve. 70 injects the gas fuel into the ignition chamber 80 to inject a flame into the cylinder chamber CC, and then the first gas fuel injection valve 50 injects the gas fuel into the cylinder chamber CC to thereby enter the cylinder chamber CC. Since the gas fuel is burned, it can be ignited reliably. Further, since the ignition fuel is self-ignited not in the cylinder chamber CC but in the ignition chamber 80, the amount of ignition fuel used can be reduced and the amount of carbon dioxide emission can be suppressed.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, A design change is possible suitably in the range which does not deviate from the summary of this invention. For example, the illustrated diesel engine 1 includes a first gas fuel injection valve 50, a pilot valve 60, and a second gas fuel injection valve 70 in the center, and includes a plurality of these valves 50, 60, and 70. It may be a configuration. The first gas fuel injection valve 50 and the second gas fuel injection valve 70 may be configured to appropriately use seal oil or ignition fuel as hydraulic oil for moving the valve bodies 51 and 71. . For example, at the time of opening the valve, a configuration may be adopted in which the valve is opened by breaking the pressure balance by releasing a part of the hydraulic oil.

1 Diesel engine 10 Cylinder head (cylinder)
20 Cylinder liner (cylinder)
30 Piston 50 First Gas Fuel Injection Valve 60 Pilot Valve 70 Second Gas Fuel Injection Valve 80 Ignition Chamber CC Cylinder Chamber

Claims (2)

A diesel engine comprising a cylinder having a cylinder chamber and a piston that reciprocates in the cylinder chamber,
A first gas fuel injection valve for injecting gas fuel into the cylinder chamber;
An ignition chamber communicating with the cylinder chamber;
A pilot valve for injecting ignition fuel into the ignition chamber;
A second gas fuel injection valve for injecting gas fuel into the ignition chamber;
A diesel engine characterized by comprising: A diesel engine control method for controlling the diesel engine according to claim 1 by a controller that controls opening and closing of the first gas fuel injection valve, the pilot valve, and the second gas fuel injection valve,
The control unit opens the pilot valve and injects the ignition fuel into the ignition chamber to self-ignite the ignition fuel in the ignition chamber;
The control unit opens the second gas fuel injection valve and injects the gas fuel into the ignition chamber, thereby amplifying the flame caused by the self-ignition of the ignition fuel and injecting it into the cylinder chamber. Steps,
The controller opens the first gas fuel injection valve and injects the gas fuel into the cylinder chamber, thereby burning the gas fuel in the cylinder chamber;
The diesel engine control method characterized by including.

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