JP2514445B2 - Fuel control device for dual fuel engine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dual fuel engine that uses two types of fuel in combination, and particularly relates to the supply amount of both fuels when the dual fuel engine is started. It relates to a fuel regulating device for controlling.

(Prior Art) In the field of this type of dual fuel engine, as a conventional example in which a liquid fuel as a main fuel and a gas fuel as a pilot fuel are used together, Japanese Patent Application Laid-Open No.
-182432 can be mentioned. The fifth example in this conventional example
As shown in the figure, the main fuel injection pump 1 and the pilot fuel injection pump 2 are respectively rack rods 3 for adjusting the fuel injection amount,
4, the internal plungers are rotated by adjusting the positions of the rack rods 3 and 4, and the fuel injection amount from the pumps 1 and 2 into the cylinder 5 is adjusted. Positioners 6 and 7 are connected to the left ends of the rack rods 3 and 4 in the figure, and these are further connected to each other by a balance lever 8. The balance lever 8 is connected to a fuel adjusting governor 9 via a link system 10. In addition, the governor 9 and both positions 6,
The operation panel 11 is configured to be remotely controllable by an operation panel 11, and the remote control from the operation panel 11 controls the supply amounts of both fuels. This fuel adjusting device exhibits the fuel injection characteristics as shown in FIG. That is, the fuel injection amount Q of the main fuel shown by the solid line and the fuel injection amount Q of the pilot fuel shown by the broken line increase in proportion to the increase in the moving amount R _S of the rack rods 3 and 4 from the start a. . The injection quantity Q of the pilot fuel is almost half of the main fuel.

Further, as a prior art for controlling the injection timing of both fuels,
JP-A-58-174122 can be mentioned.

(Problems to be Solved by the Invention) However, in the above-described conventional example, only the fuel injection amount control as shown in FIG. 4 can be performed, and therefore, there is a problem that the ignitability of the engine is poor, while the positioners 6, 7
There is also a problem that the structure becomes complicated because the or balance lever 8 is required.

The present invention has been made to solve the above-mentioned conventional problems, and an object thereof is to provide a fuel adjustment device for a dual fuel engine, which can improve ignition performance at the time of starting and has a simple structure. To do.

(Means for Solving the Problems) Therefore, in the fuel adjusting device for the dual fuel engine according to the first aspect, a main fuel injection pump having a fuel adjusting governor and a rack rod for adjusting the fuel injection amount, In a fuel adjustment device for a dual fuel engine, which includes a pilot fuel injection pump and a link system that connects the governor and the rack rods of both injection pumps, at the time of starting, in the fuel increasing direction of the rack rod of the main fuel injection pump. Of the pilot fuel injection pump by connecting the delay mechanism for stopping the movement of the fuel injection start timing to the high load side to the rack rod of the main fuel injection pump and adjusting the link system when the delay mechanism operates. A buffer mechanism that allows movement of the rack rods in the fuel increasing direction is connected to the link system.

Further, in the fuel adjusting device for the dual fuel engine according to the second aspect, the lead shape of the plunger of the pilot fuel injection pump is formed so as not to increase the fuel injection amount after the start is completed.

(Operation) In the first aspect, the governor operates at the time of starting to move the link system in the fuel increasing direction. At the time of starting, the delay mechanism stops the movement of the rack rod of the main fuel injection pump in the fuel increasing direction, and prevents the main fuel from being injected from the main fuel injection pump. On the other hand, the rack rod of the pilot fuel injection pump moves in the fuel increasing direction even at the time of starting by the adjusting function of the link system by the buffer mechanism,
Pilot fuel is injected from the start of the engine. As described above, the pilot fuel is injected by a predetermined injection amount at the time of starting, and the injection of the main fuel is stopped, and only the pilot fuel having good ignitability is injected at the time of starting. When the governor continues to increase fuel and the link system moves in the direction of increasing fuel, the delay mechanism stops operating at a predetermined position and the rack rod of the main fuel injection pump moves in the direction of increasing fuel to inject main fuel. Start.

Since the injection control of both fuels at the time of starting is performed by the functions of the delay mechanism and the buffer mechanism, the link mechanism has a function of moving the rack rods of both injection pumps with the operation of a single governor. Since the structure of the link system is simplified, the number of governors can be reduced.

Further, in the second aspect, since the injection amount of the pilot fuel does not increase after the completion of the start, the consumption amount of the pilot fuel decreases and the fuel economy improves.

(Embodiment) Next, a specific embodiment of the fuel adjustment device for a dual fuel engine of the present invention will be described in detail with reference to the drawings.

In FIG. 1, reference numeral 20 denotes a main fuel injection pump that injects, for example, methanol as a main fuel, and a pilot fuel injection pump 21 that injects, for example, heavy oil as a pilot fuel is arranged in parallel with the main fuel injection pump 20. .
The main fuel injection pump 20 and the pilot fuel injection pump 21 are provided with rack rods 22 and 23 and plungers 24 and 25, respectively.The plungers 24 and 25 are moved up and down by the cam shafts 26 and 27, and fuel is added to the top of the plungers 24 and 25. Plungers 24, 25 having notched lead portions (not shown) for adjusting the injection amount
Is rotated by the rack rods 22 and 23, and the injection characteristics of the main fuel and pilot fuel can be controlled according to the operating state of the engine.

Meanwhile, the main fuel injection pump 20 and the pilot fuel injection pop
A governor 30 for fuel adjustment is arranged near 21.
The left end of a rod 32 forming a part of a link system is connected to the arm 31 of the governor 30, and the rod 32 is operated by the operation of the governor 30 in the fuel increasing direction and the fuel decreasing direction. There is. The right end of rod 32 is the control shaft.
It is connected to the arm 35 of 34. The control axis 34 has an arm 35
Besides, arms 36 and 37 are fixed, and one arm
Reference numeral 36 is connected to the rack rod 22 of the main fuel injection pump 20 via a buffer mechanism 40, and the other arm 37 is connected to the rack rod 23 of the pilot fuel injection pump 21 via a rod 41.

A stop cylinder 42 (delay mechanism) is connected to the rack rod 22, and the solenoid valve 44 controls the inflow of the working fluid into the chamber 43 of the stop cylinder 42.
At the time of starting, the movement of the rack rod 22 in the fuel increasing direction is blocked so that the injection start of the main fuel injection pump 20 is delayed. The solenoid valve 44 has a function of receiving the engine start signal and holding the stop cylinder 42 in the extended state, while returning to the shortened state by the spring 47 during steady operation. On the other hand, the buffer mechanism 40 is configured such that a slide plate 46 is slidably accommodated in a substantially cylindrical cylinder 45, and a compression coil spring 47 for urging the slide plate 46 in the extending direction is arranged in the cylinder 45. Has been done.
The buffer mechanism 40 absorbs the rotation of the arm 36 when the arm 36 is rotated in the fuel increasing direction while the stop cylinder 42 is operating at the time of starting, and the length of the link system is increased. It has a function to adjust.

Further, the plunger of the pilot fuel injection pump 21
The shape of the lead portion (not shown) formed on the top of 25 is such that the injection characteristics are such that the fuel injection starts from the start a of the engine as shown by the broken line in FIG.
The fuel injection amount Q is increased in proportion to the rack movement amount R _S , and the fuel injection amount Q is not increased after the completion of the start-up, and the fuel injection amount Q is maintained substantially constant.

Next, an operation state of the above-described embodiment device will be described. At the start of engine start, the solenoid valve 44 is opened by the start signal to maintain the stop cylinder 42 in the extended state. The stop cylinder 42 prevents the rack rod 22 of the main fuel injection pump 20 from starting to move in the fuel increasing direction until reaching the point b in FIG. On the other hand, the buffer mechanism 40
By shortening, the rack rod 23 of the pilot fuel injection pump 21 moves in the fuel increasing direction, and gradually increases the fuel injection amount Q. As described above, in the interval of Δl from the start time point a to the intermediate time point b in FIG. 3, only the pilot fuel having a good ignitability at the time of starting is injected from the pilot fuel injection pump 21, and the ignition of the engine is prevented. It will be easier. And at the intermediate point b, the stop cylinder
By returning 42 and starting the injection of the main fuel from the main fuel injection pump 20 as shown by the solid line in FIG. 3, the pilot fuel becomes the ignition point and the main fuel is easily ignited. The stable combustion can be continued at the completion time point c. After the start-up completion time point c, the injection amount Q of the pilot fuel does not increase and is suppressed to a substantially constant injection amount Q, while the injection amount Q of the main fuel increases in proportion to the rack movement amount R _S.

In the above one embodiment, the injection of the main fuel is stopped at the time of starting, while the injection of the pilot fuel is performed, so that the ignitability at the time of starting is improved and the engine is easily started. Further, since the injection amount Q of the pilot fuel does not increase after the start completion time point c and is suppressed to a substantially constant injection amount Q, the consumption amount of the pilot fuel in the normal operation state where stable combustion with the main fuel is possible. Will be reduced and fuel economy will be improved. Further, as compared with the conventional example shown in FIG. 5, since it is not necessary to provide the balancing lever 8, the structure of the link system is simple. In particular, when methanol is used as the main fuel and heavy oil is used as the pilot fuel as in this embodiment, the control range of the pilot injection system is larger than that when gas fuel is used as the main fuel in FIG. Is narrower than that of the conventional example shown in FIG. 5, so that a simple link system as shown in FIG. 1 can sufficiently fulfill the fuel adjustment function. Moreover, cost reduction is achieved by simplifying the structure of the link system.

It is also possible to use a link system having another structure as shown in FIG. In the second embodiment of FIG. 2,
Two main fuel injection pumps 20 and two pilot fuel injection pumps 21 are respectively controlled by the main fuel control shaft 50 and the pilot control shaft 51 to control the fuel injection amount. The arm 52 of the main fuel control shaft 50 is a rod
It is connected to the arm 31 of the governor 30 at 53, and the pilot control shaft
The arm 54 of 51 is connected to the arm 31 by a rod 55. Further, the stop cylinder 42 is connected to the arm 61 of the main fuel control shaft 50 via the rod 64, and the stop cylinder 42 that also serves as the delay mechanism and the buffer mechanism includes the control shaft 50, the arms 36, 61, and the rod 64. It is connected to the rack bar 22 via. A compression coil spring 63 for returning the stop cylinder 42 to the shortened state is housed inside the stop cylinder 42.

In the configuration of FIG. 2 described above, it is sufficient to provide only one stop cylinder 42 and a buffer mechanism for two main fuel injection pumps 20, that is, one main fuel injection pump.
20 respectively, buffer mechanism 40 and stop cylinder 42
Stop cylinder 42 compared to the case of FIG.
Also, the number of cushioning mechanisms 60 is reduced, and the cost can be reduced.

Although the specific embodiments of the fuel adjusting device for the dual fuel engine of the present invention have been described above, the present invention is not limited to the above embodiments, and various modifications may be made within the scope of the present invention. It is possible. For example, in the above-described one embodiment, methanol is used as the main fuel and heavy oil is used as the pilot fuel, but it is also possible to employ a combination of other fuels.

(Advantages of the Invention) As described above, in the fuel adjustment device for a dual fuel engine according to the first aspect, the pilot fuel can be injected by a predetermined injection amount at the time of starting, and the injection of the main fuel can be stopped. The ignitability at the time of starting can be improved. Moreover, since the injection control of both fuels at the time of starting is performed by the functions of the delay mechanism and the buffer mechanism, the structure of the link system can be simplified and the number of governors can be reduced.

Further, in the fuel adjusting device for the dual fuel engine according to the second aspect, it is possible to prevent the injection amount of the pilot fuel from increasing after completion of the start, reduce the consumption amount of the pilot fuel, and improve the fuel economy. You can

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a fuel adjusting device for a dual fuel engine according to the present invention, and FIG. 2 is a perspective view showing another embodiment of a fuel adjusting device for a dual fuel engine according to the present invention. Three
FIG. 4 is a graph showing a change in the fuel injection amount with respect to the rack movement amount in the embodiment of FIG. 1, and FIG. 4 is a graph showing a change in the fuel injection amount with respect to the rack movement amount in the conventional example.
FIG. 5 is a schematic structural view showing a conventional example. 20 …… Main fuel injection pump, 21 …… Pilot fuel injection pump, 22,23 …… Rack rod, 30 …… Governor, 34 …… Control shaft, 40 …… Buffer mechanism, 42 …… Stop cylinder (delay mechanism) .

Claims (2)

(57) [Claims] 1. A fuel adjustment governor, a main fuel injection pump and a pilot fuel injection pump each having a rack rod for adjusting a fuel injection amount, and a link system connecting the governor and the rack rods of both injection pumps. And a delay mechanism for delaying the fuel injection start timing to the high load side by stopping the movement of the rack rod of the main fuel injection pump in the fuel increasing direction at the time of starting, A buffer mechanism was connected to the rack rod of the main fuel injection pump, and the link system was adjusted when the delay mechanism was activated to allow movement of the rack rod of the pilot fuel injection pump in the fuel increasing direction. A fuel adjustment device for a dual fuel engine, characterized in that 2. The dual fuel engine according to claim 1, wherein the lead shape of the plunger of the pilot fuel injection pump is formed so as not to increase the fuel injection amount after completion of starting. Fuel regulator.