JP2014098339A - Control device for diesel engine, diesel engine, and method for controlling diesel engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an usage amount of oil fuel and enable stable operation by using the oil fuel and gaseous fuel.SOLUTION: An ECU provided in a dual fuel diesel engine performs a governor control, and supplies only oil fuel when a load factor is equal to or less than a switch load factor, and starts a supply of gaseous fuel when the load factor becomes larger than the switch load factor. The ECU controls the oil fuel and the gaseous fuel in different control amounts, and increases a total supply heat amount of the gaseous fuel and the oil fuel in accordance with increase of the load. A fuel control unit provided in the ECU starts the supply of gaseous fuel when the load factor becomes larger than the switch load factor, and keeps a supply amount of the gaseous fuel constant irrespective of the increase of the load, and increases a supply amount of the oil fuel in accordance with the increase of the load.

Description

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

Diesel engine that uses natural gas or other gas fuel as the main fuel, oil fuel with good compression ignitability as pilot fuel, and self-ignition of the oil fuel in the combustion chamber under high temperature to burn the main fuel gas fuel ( Hereinafter, “dual fuel diesel engine” is known). Since the dual fuel diesel engine uses gas fuel, it emits less CO ₂ during combustion and emits less harmful substances such as black smoke.

  For example, Patent Document 1 discloses a dual fuel diesel engine in which a low cetane number fuel with poor compression ignitability such as gas fuel is used as a main fuel and an oil fuel with good compression ignitability is used as a pilot fuel. The engine disclosed in Patent Document 1 includes a gas fuel injection valve and a pilot fuel injection valve provided in a cylinder head. Gas fuel and pilot fuel are supplied from the gas fuel injection valve and the pilot fuel injection valve toward the combustion chamber. By injecting, the pilot fuel is self-ignited in the high-temperature combustion chamber, thereby burning the main fuel.

Japanese Utility Model Publication No. 62-45339

  However, Patent Document 1 does not specifically disclose a method for supplying oil fuel and gas fuel to a diesel engine. In a dual fuel diesel engine, stable operation using oil fuel and gas fuel becomes an issue.

  The present invention has been made in view of such circumstances, and reduces the amount of oil fuel used and enables a stable operation using oil fuel and gas fuel. An object of the present invention is to provide a diesel engine and a method for controlling the diesel engine.

  In order to solve the above-described problems, the diesel engine control device, the diesel engine, and the diesel engine control method of the present invention employ the following means.

  A control device for a diesel engine according to a first aspect of the present invention is a control device for a diesel engine that is operated by being supplied with gas fuel and oil fuel, and includes a governor control means for performing governor control, and a load on the diesel engine. When only the oil fuel is supplied when it is below a predetermined value, when the load exceeds the predetermined value, the supply of the gas fuel is started, and the gas fuel and the oil fuel are controlled with different control amounts, And fuel control means for increasing the total supply heat amount of the gas fuel and the oil fuel in accordance with the increase in the load.

  According to this configuration, the control device for the diesel engine controls the supply amount of gas fuel and oil fuel to the diesel engine. Gas fuel and oil fuel are supplied by governor control by the governor control means.

  The fuel control means supplies only oil fuel when the load of the diesel engine is equal to or less than a predetermined value. The case where the load is equal to or less than the predetermined value is a case where the load is low. Since oil fuel has better compression ignitability than gas fuel, by supplying only oil fuel at low load, the diesel engine can operate stably even at low load.

The fuel control means starts supplying the gas fuel when the load exceeds a predetermined value, controls the gas fuel and the oil fuel with different control amounts, and controls the gas fuel and the oil fuel according to the increase in the load. Increase total heat supply. Thereby, this structure can reduce the usage-amount of the oil fuel of a diesel engine. Moreover, since this structure controls gas fuel and oil fuel by a different control amount, it can control different gas fuel and oil fuel according to the objective.
From the above, this configuration reduces the amount of oil fuel used, and enables stable operation using oil fuel and gas fuel.

  In the first aspect, when the load exceeds the predetermined value, the fuel control means starts supplying the gas fuel and makes the supply amount of the gas fuel constant regardless of an increase in the load, It is preferable to increase the supply amount of the oil fuel according to the increase of the load.

  According to this configuration, the supply amount of the gas fuel is constant regardless of the increase in the load, and the supply amount of the oil fuel is increased according to the increase in the load, so that the governor control is performed with the oil fuel. And since this structure makes the supply amount of gaseous fuel constant, even when the residual amount of gaseous fuel is small, the driving | operation of the diesel engine using gaseous fuel is attained.

  In the first aspect, it is preferable that, when the load exceeds the predetermined value, the fuel control means increases the supply amount of the gas fuel with time change to the constant supply amount.

When the load exceeds a predetermined value, if the gas fuel is supplied in a sudden increase, the rotational speed of the diesel engine may increase rapidly. In such a case, the governor control reduces the fuel supply amount in order to reduce the increased rotational speed, but as a result, there is a possibility of so-called chattering in which the rotational speed is too low.
According to this configuration, by increasing the gas fuel supply amount with time change until a constant supply amount is reached, the rapid increase in the rotational speed of the diesel engine is suppressed, thus preventing chattering. Can do.

  In the first aspect, when the load exceeds the predetermined value, the fuel control means causes the gas fuel and the oil fuel to have a predetermined ratio between the gas fuel and the oil fuel. Are preferably supplied.

  According to this configuration, since the co-firing ratio of gas fuel and oil fuel is arbitrarily set, the diesel engine can be operated in a more suitable state.

  In the first aspect, when the load exceeds the predetermined value, the fuel control means starts supplying the gas fuel and makes the supply amount of the oil fuel constant regardless of the increase in the load, It is preferable to increase the supply amount of the gas fuel in accordance with the increase in the load.

  According to this configuration, the supply amount of the oil fuel is made constant regardless of the increase in the load, and the supply amount of the gas fuel is increased according to the increase in the load. Therefore, the governor control is performed with the gas fuel. And since this structure makes the supply amount of oil fuel constant, the usage-amount of oil fuel can be reduced and the effect acquired by gas fuel can be exhibited to the maximum.

  A diesel engine according to a second aspect of the present invention includes a gas fuel injection valve that injects gas fuel into a combustion chamber, an oil fuel injection valve that injects oil fuel into the combustion chamber, and the control device described above. .

  A method for controlling a diesel engine according to a third aspect of the present invention is a method for controlling a diesel engine operated by being supplied with gas fuel and oil fuel, and the oil fuel is loaded when a load of the diesel engine is equal to or less than a predetermined value. A first step of supplying only the gas, a second step of starting supply of the gas fuel when the load exceeds the predetermined value, controlling the gas fuel and the oil fuel with different control amounts, and And a third step of increasing the total supply heat amount of the gas fuel and the oil fuel in response to an increase in the load.

  According to the present invention, there is an excellent effect of reducing the amount of oil fuel used and enabling stable operation using oil fuel and gas fuel.

1 is a configuration diagram of a dual fuel diesel engine according to a first embodiment of the present invention. FIG. 1 is a block diagram showing an electrical configuration of an ECU according to a first embodiment of the present invention. It is a graph which shows the relationship between the sum of the fuel control command of the oil fuel which concerns on 1st Embodiment of this invention, and gas fuel, and a load factor. It is a graph which shows the relationship between the load factor and oil fuel control command which concern on 1st Embodiment of this invention, and the relationship between a load factor and gas fuel control command. It is a graph which shows the relationship between the load factor and oil fuel control command which concern on 2nd Embodiment of this invention, and the relationship between a load factor and gas fuel control command. It is a graph which shows the relationship between the load factor and oil fuel control command which concern on 3rd Embodiment of this invention, and the relationship between a load factor and gas fuel control command. It is a graph which shows the relationship between the load factor and oil fuel control command which concern on 4th Embodiment of this invention, and the relationship between a load factor and gas fuel control command.

  EMBODIMENT OF THE INVENTION Below, one Embodiment of the control apparatus of the diesel engine which concerns on this invention, a diesel engine, and the control method of a diesel engine is described with reference to drawings.

[First Embodiment]
The first embodiment of the present invention will be described below.
The diesel engine according to the first embodiment is a dual fuel diesel engine that is operated using gas fuel as main fuel and oil fuel as pilot fuel, and is used as, for example, a main engine of a ship.

FIG. 1 is a configuration diagram of a dual fuel diesel engine 1 according to the first embodiment.
The dual fuel diesel engine 1 includes a cylindrical cylinder 2, a cylinder head 3 coupled to the upper end side of the cylinder 2, and a piston 4 accommodated in the cylinder 2 so as to be able to advance and retract. A combustion chamber c is formed by the peripheral wall 2 a of the cylinder 2, the cylinder head 3, and the top surface 4 a of the piston 4.
In addition, the code | symbol 5 in a figure has shown the piston ring.

  A scavenging port 6 is opened in the peripheral wall 2 a on the lower side of the cylinder 2. The scavenging port 6 is formed at a position above the top surface 4a of the piston 4 located near the bottom dead center (indicated by a two-dot chain line in the figure), and the piston 4 is located near the bottom dead center. Sometimes, air is supplied from the scavenging port 6 to the combustion chamber c. An exhaust port is opened at the top of the cylinder head 3 and an exhaust valve 7 for opening and closing the exhaust port is provided. The exhaust valve 7 is opened until the piston 4 reaches a position of about 100 ° before top dead center during the scavenging stroke when the piston 4 is in the upward stroke. The exhaust gas in the previous stroke remaining in the combustion chamber c is scavenged by the air supplied from the scavenging port 6 to the combustion chamber c.

  The cylinder head 3 is provided with a gas fuel injection valve 8 that injects gas fuel into the combustion chamber c, and is also provided with an oil fuel injection valve 10 that injects oil fuel with good compression ignitability into the combustion chamber c. . The gas fuel injection valve 8 and the oil fuel injection valve 10 are provided one by one at positions 180 degrees apart in the circumferential direction with the cylinder center o as the center of rotation.

  In the first embodiment, the gas fuel injection valve 8 and the oil fuel injection valve 10 are each provided with four injection holes. However, the number of gas fuel injection valves 8 and the oil fuel injection valves 10 installed is as follows. It is not limited, For example, you may be one. However, in the first embodiment in which the exhaust valve 7 is provided at the top of the cylinder head 3, a plurality of gas fuel injection valves 8 and oil fuel injection valves 10 are arranged at equal intervals in the circumferential direction. It is preferable.

Further, the gas fuel injection valve 8 and the oil fuel injection valve 10 are connected to an engine control unit (hereinafter referred to as “ECU”) 12 via a cable 14.
The ECU 12 is connected via a cable 16 to a crank angle sensor 15 that detects a rotation angle of the crankshaft 17. The phase of the piston 4 is detected by receiving a signal related to the rotation angle of the crankshaft 17 from the crank angle sensor 15. Further, the gas fuel injection valve 8 and the oil fuel injection valve 10 inject gas fuel and oil fuel into the combustion chamber c at a predetermined timing based on a signal transmitted from the ECU 12.

FIG. 2 is a block diagram showing an electrical configuration of the ECU 12 according to the first embodiment.
The ECU 12 includes a governing control unit 30 and a fuel control unit 32.

  The governing control unit 30 receives the set rotational speed and the actual rotational speed of the dual fuel diesel engine 1 and performs the governing so that the actual rotational speed becomes the set rotational speed based on the difference between the set rotational speed and the actual rotational speed. Take control. Note that the governing control unit 30 may perform the governing control based on the difference between the set load and the actual load. The load according to the first embodiment is specified by a load factor (load indicator value) that varies between 0 and 100, with the maximum load on the dual fuel diesel engine 1 being 100%.

  The fuel control unit 32 outputs a fuel control command based on the command output from the governing control unit 30.

The fuel control unit 32 according to the first embodiment includes an oil fuel control unit 34 and a gas fuel control unit 36.
The oil fuel control unit 34 calculates an oil fuel control command by a predetermined function based on the command output from the governing control unit 30 and outputs the oil fuel control command to the oil fuel injection valve 10.
The gas fuel control unit 36 calculates an oil fuel control command by a predetermined function based on the command output from the governing control unit 30 and outputs the oil fuel control command to the gas fuel injection valve 8.

FIG. 3 is a graph showing the relationship between the load factor and the fuel control command.
The fuel control command shown in FIG. 3 is the sum of the oil fuel control command and the gas fuel control command. That is, the total supply heat amount of the gas fuel and the oil fuel increases as the load factor increases. As an example, the fuel control command increases in proportion to the load factor.

The fuel control unit 32 supplies only oil fuel when the load of the dual fuel diesel engine 1 is equal to or less than a predetermined value, and starts supplying gas fuel when the load exceeds a predetermined value. The fuel control unit 32 controls the gas fuel and the oil fuel with different control amounts, and increases the total supply heat amount of the gas fuel and the oil fuel according to the increase in the load as shown in FIG. Thereby, ECU12 can reduce the usage-amount of the oil fuel of the dual fuel diesel engine 1. FIG. Further, since the ECU 12 controls the gas fuel and the oil fuel with different control amounts, the ECU 12 can control different gas fuel and oil fuel depending on the purpose.
In addition, the said predetermined value is called switching load factor in the following description. In the first embodiment, the switching load factor is 20% as an example, but is not limited to this and is arbitrarily set. Below the switching load factor is a load factor for low load operation.

  When the load exceeds the switching load factor, the fuel control unit 32 according to the first embodiment starts supplying the gas fuel and keeps the supply amount of the gas fuel constant regardless of the increase in the load. Increase the amount as the load increases.

  FIG. 4 is a graph showing the relationship between the load factor and the oil fuel control command and the relationship between the load factor and the gas fuel control command according to the first embodiment.

As shown in FIG. 4, when the load factor is equal to or less than the switching load factor (20%), only the oil fuel control command is output, and the oil fuel control command increases as the load factor increases. Since the oil fuel has better compression ignitability than the gas fuel, the dual fuel diesel engine 1 can be stably operated even at the low load by supplying only the oil fuel at the low load.
When the load factor exceeds the switching load factor, a gas fuel control command is output and becomes a constant value, and supply of gas fuel to the dual fuel diesel engine 1 is started. As described above, when the load factor exceeds the switching load factor, the dual fuel diesel engine 1 is switched from the operation state that has been exclusively fired by the oil fuel to the mixed combustion state of the oil fuel and the gas fuel.

  On the other hand, when the load factor exceeds the switching load factor, the increase rate of the oil fuel control command becomes smaller than that less than the switching load factor. In other words, the oil fuel control command is a value obtained by subtracting the gas fuel control command from the fuel control command shown in FIG. Due to the decrease in the oil fuel control command, the relationship between the fuel control command and the load factor is maintained as shown in FIG.

  That is, in the first embodiment, when the load factor exceeds the switching load factor, the opening / closing time of the gas fuel injection valve 8 is fixed, and the opening / closing time of the oil fuel injection valve 10 varies. Thus, governor control is performed.

  As described above, the ECU 12 provided in the dual fuel diesel engine 1 according to the first embodiment performs governor control, and supplies only oil fuel when the load factor is equal to or lower than the switching load factor, and the load factor is switched. When the load factor is exceeded, the supply of gas fuel is started, the gas fuel and the oil fuel are controlled with different control amounts, and the total supply heat amount of the gas fuel and the oil fuel is increased as the load increases. Therefore, the ECU 12 according to the first embodiment can reduce the amount of oil fuel used and can stably operate using oil fuel and gas fuel.

  When the load factor exceeds the switching load factor, the fuel control unit 32 included in the ECU 12 according to the first embodiment starts supplying the gas fuel and keeps the supply amount of the gas fuel constant regardless of the increase in the load. And the supply amount of the oil fuel is increased according to the increase of the load. Therefore, the fuel control unit 32 according to the first embodiment can operate the diesel engine using the gas fuel even when the remaining amount of the gas fuel is small.

[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described.

The configurations of the dual fuel diesel engine 1 and the ECU 12 according to the second embodiment are the same as the configurations of the dual fuel diesel engine 1 and the ECU 12 according to the first embodiment shown in FIGS. .
The ECU 12 according to the second embodiment supplies only oil fuel when the load factor of the dual fuel diesel engine 1 is equal to or lower than the switching load factor, and the load factor is the switching load, as in the first embodiment. When the rate is exceeded, gas fuel supply is started.

  However, if the gas fuel is steeply increased and supplied when the load factor exceeds the switching load factor, the rotational speed of the dual fuel diesel engine 1 may rapidly increase. In such a case, the governor control reduces the fuel supply amount in order to reduce the increased rotational speed, but as a result, there is a possibility of so-called chattering in which the rotational speed is too low.

  Therefore, when the load factor of the dual fuel diesel engine 1 exceeds the switching load factor, the fuel control unit 32 according to the second embodiment increases the supply amount of the gas fuel with a change over time to maintain a constant supply. Amount.

  FIG. 5 is a graph showing the relationship between the load factor and the oil fuel control command and the relationship between the load factor and the gas fuel control command according to the second embodiment.

As shown in FIG. 5, when the load factor reaches the switching load factor (20%), the gas fuel control command increases and the supply of gas fuel to the dual fuel diesel engine 1 is started. As a result, the dual fuel diesel engine 1 is in a mixed combustion state of oil fuel and gas fuel. In this case, the gas fuel rises to a certain value at a predetermined rate of increase so that the supply amount changes with time.
On the other hand, when the load factor exceeds the switching load factor, the oil fuel control command becomes a value obtained by subtracting the gas fuel control command from the fuel control command shown in FIG. Smaller than less.

  As described above, the fuel control unit 32 according to the second embodiment rapidly increases the rotational speed of the dual fuel diesel engine 1 by increasing the supply amount of the gas fuel with time change until the constant supply amount is reached. Therefore, chattering can be prevented from occurring.

[Third Embodiment]
Hereinafter, a third embodiment of the present invention will be described.

  The configurations of the dual fuel diesel engine 1 and the ECU 12 according to the third embodiment are the same as the configurations of the dual fuel diesel engine 1 and the ECU 12 according to the first embodiment shown in FIGS. .

The ECU 12 according to the third embodiment supplies only oil fuel when the load factor of the dual fuel diesel engine 1 is equal to or lower than the switching load factor, and supplies gas fuel when the load factor exceeds the switching load factor. Start.
In the fuel control unit 32 according to the third embodiment, when the load factor exceeds the switching load factor, the ratio between the gas fuel and the oil fuel is a predetermined value (hereinafter referred to as “set mixed combustion ratio”). Gas fuel and oil fuel are supplied so that The set mixed firing ratio is arbitrarily settable and can be changed depending on the load factor.

  Depending on the load factor, for example, a higher ratio of gas fuel or oil fuel may enable more stable operation or more efficient operation of the dual fuel diesel engine 1 in some cases. For this reason, the fuel control unit 32 according to the third embodiment allows the set mixed combustion ratio to be arbitrarily set in order to operate the dual fuel diesel engine 1 in a more suitable state.

  FIG. 6 is a graph showing the relationship between the load factor and the oil fuel control command and the relationship between the load factor and the gas fuel control command according to the third embodiment.

As shown in FIG. 6, when the load factor reaches the switching load factor (20%), the gas fuel control command increases, and the supply of gas fuel to the dual fuel diesel engine 1 is started. It is said to be in a mixed firing state. In this case, the gas fuel increases as the load factor increases.
On the other hand, when the load factor becomes the switching load factor, the oil fuel control command increases as the load factor increases although the increase rate decreases according to the amount of gas fuel supplied.
The gas fuel control command and the oil fuel control command are controlled so that the ratio of the gas fuel and the oil fuel becomes the set mixed combustion ratio.

  That is, in the third embodiment, when the load factor exceeds the switching load factor, the opening / closing time of the gas fuel injection valve 8 and the oil fuel injection valve 10 varies, so that the governor control is performed with the gas fuel and the oil fuel. Will be done.

  Thus, the fuel control unit 32 according to the third embodiment supplies the gas fuel and the oil fuel so that the ratio of the gas fuel and the oil fuel becomes the set mixed combustion ratio when the load factor exceeds the switching load factor. Therefore, the dual fuel diesel engine 1 can be operated in a more suitable state.

[Fourth Embodiment]
The fourth embodiment of the present invention will be described below.

  The configurations of the dual fuel diesel engine 1 and the ECU 12 according to the fourth embodiment are the same as the configurations of the dual fuel diesel engine 1 and the ECU 12 according to the first embodiment shown in FIGS. .

The ECU 12 according to the fourth embodiment supplies only oil fuel when the load factor of the dual fuel diesel engine 1 is equal to or lower than the switching load factor, and supplies gas fuel when the load factor exceeds the switching load factor. Start.
Then, when the load factor exceeds the switching load factor, the fuel control unit 32 according to the fourth embodiment starts supplying gas fuel and makes the supply amount of oil fuel constant regardless of the increase in load. The fuel supply amount is increased according to the increase in load.

  FIG. 7 is a graph showing the relationship between the load factor and the oil fuel control command and the relationship between the load factor and the gas fuel control command according to the fourth embodiment.

As shown in FIG. 7, the oil fuel control command increases as the load factor increases until the load factor reaches the switching load factor (20%), but becomes constant when the load factor reaches the switching load factor.
On the other hand, the gas fuel control command increases when the load factor becomes the switching load factor, and the supply of gas fuel to the dual fuel diesel engine 1 is started. As a result, the dual fuel diesel engine 1 is in a mixed combustion state of oil fuel and gas fuel. The gas fuel control command increases as the load factor increases. As a result, the relationship between the fuel control command and the load factor is maintained as shown in FIG.

  That is, in the fourth embodiment, when the load factor exceeds the switching load factor, the opening / closing time of the oil fuel injection valve 10 is fixed and the opening / closing time of the gas fuel injection valve 8 varies. The governor control will be performed.

  As described above, when the load factor exceeds the switching load factor, the fuel control unit 32 according to the fourth embodiment starts supplying gas fuel and makes the supply amount of oil fuel constant regardless of the load increase. Since the supply amount of gas fuel is increased in accordance with the increase in load, the amount of oil fuel used can be reduced and the effect obtained by the gas fuel can be maximized.

  As mentioned above, although this invention was demonstrated using said each embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. Various changes or improvements can be added to the above-described embodiments without departing from the gist of the invention, and embodiments to which the changes or improvements are added are also included in the technical scope of the present invention.

1 Dual fuel diesel engine 12 ECU
30 Governing control unit 32 Fuel control unit

Claims (7)

A control device for a diesel engine operated by being supplied with gas fuel and oil fuel,
Governor control means for performing governor control;
When the load of the diesel engine is less than or equal to a predetermined value, only the oil fuel is supplied, and when the load exceeds the predetermined value, the supply of the gas fuel is started, and the gas fuel and the oil fuel are controlled differently. Fuel control means for controlling the amount and increasing the total supply heat amount of the gas fuel and the oil fuel in response to an increase in the load;
A diesel engine control device.   When the load exceeds the predetermined value, the fuel control means starts supplying the gas fuel, makes the supply amount of the gas fuel constant regardless of the increase in the load, and sets the supply amount of the oil fuel. The control device for a diesel engine according to claim 1, wherein the control device raises the load in response to an increase in the load.   The control device for a diesel engine according to claim 2, wherein, when the load exceeds the predetermined value, the fuel control means increases the supply amount of the gas fuel with a time change to the constant supply amount.   The fuel control means supplies the gas fuel and the oil fuel so that a ratio of the gas fuel and the oil fuel becomes a predetermined value when the load exceeds the predetermined value. The control apparatus of the diesel engine of 1.   When the load exceeds the predetermined value, the fuel control means starts supplying the gas fuel, makes the supply amount of the oil fuel constant regardless of the increase in the load, and sets the supply amount of the gas fuel. The control device for a diesel engine according to claim 1, wherein the control device raises the load in response to an increase in the load. A gas fuel injection valve for injecting gas fuel into the combustion chamber;
An oil fuel injection valve for injecting oil fuel into the combustion chamber;
A control device according to any one of claims 1 to 5;
Diesel engine equipped with. A method for controlling a diesel engine operated by being supplied with gas fuel and oil fuel,
A first step of supplying only the oil fuel when the load of the diesel engine is a predetermined value or less;
A second step of starting supply of the gaseous fuel when the load exceeds the predetermined value;
A third step of controlling the gas fuel and the oil fuel with different control amounts, and increasing a total supply heat amount of the gas fuel and the oil fuel according to an increase in the load;
Control method of diesel engine including

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