JPH0332769Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a fuel supply system for a diesel engine, and in particular, the present invention relates to a fuel supply system for a diesel engine, in particular, in which fuel is atomized by an ultrasonic vibrator separately from the main fuel under a predetermined operating condition of the engine. This invention relates to an improvement in a device in which auxiliary fuel is supplied to an intake passage.

(Prior Art) Conventionally, as an engine fuel supply device that atomizes and supplies fuel to the engine, in addition to the carburetor type and fuel injection type, there are other methods such as those disclosed in Japanese Patent Application Laid-Open No. 52-112018, etc. As disclosed, fuel supplied from a fuel tank is stored in a chamber (fuel atomization tank) formed in a part of the intake passage, and the fuel in the chamber is generated by vibration of an ultrasonic vibrator. By atomizing the fuel and supplying it to the intake passage, it is possible to reduce the adhesion of fuel to the walls of the intake passage compared to the carburetor method, fuel injection method, etc., and improve the accuracy of the air-fuel ratio. Proposed.

On the other hand, in a diesel engine, the main fuel is fuel that is directly injected into the fuel chamber of the engine by a fuel injection pump, and atomized auxiliary fuel (mainly light oil) is added to the main fuel at a predetermined rate. By supplying the same proportion to the intake passage, it creates an atmosphere that facilitates ignition in the fuel chamber during the compression stroke of the engine, promoting ignitability and combustibility of the main fuel, improving engine output, reducing smoke generation, etc. It is known to do so.

(Problem that the invention attempts to solve) Therefore, in a diesel engine for a vehicle,
Using the concept in the above proposed example, the auxiliary fuel is atomized by an ultrasonic vibrator, and the atomized auxiliary fuel is supplied to the intake passage only during high-load operating conditions such as during engine acceleration. By doing so, it is possible to suppress the occurrence of smoke during high-load operating conditions of the diesel engine.

However, in this case, in order to prevent non-atomized liquid auxiliary fuel from directly flowing into the intake passage due to turning of the vehicle, etc., when the chamber for storing auxiliary fuel is formed in a separate system from the intake passage, Since fuels such as light oil are difficult to atomize, even if the ultrasonic vibrator starts operating at the same time as the engine shifts to high-load operating state, the supply of auxiliary fuel will be delayed compared to the engine's shift to high-load operating state. I ended up
The effect of the system for supplying auxiliary fuel cannot be fully demonstrated. Furthermore, if the output of the ultrasonic transducer is increased in order to eliminate the response delay during the supply of atomized fuel, a contradictory problem arises in that the ultrasonic transducer becomes larger and the power consumption increases.

The purpose of the present invention is to supply the auxiliary fuel to the intake passage when the auxiliary fuel is atomized by the ultrasonic vibrator and is supplied to the intake passage only during predetermined operating conditions of the diesel engine. By appropriately controlling the operation of the ultrasonic transducer in a normal operating state, it is possible to prevent a delay in the supply of atomized auxiliary fuel when the engine transitions to a specified operating state, and also to reduce the size of the ultrasonic transducer. The object is to make it possible to reduce the power consumption.

(Means for solving the problem) In order to achieve the above object, the configuration of the present invention is as follows:
An ultrasonic vibrator constituting a fuel atomization device that atomizes fuel is disposed in a chamber in which fuel is stored and communicates with the intake passage of the diesel engine at the upstream and downstream connection portions, respectively, and the upstream side An opening/closing valve for opening and closing the chamber with respect to the intake passage is provided at the downstream connecting portion and the downstream connecting portion, respectively.

Then, under the control of the control device, in a predetermined operating state of the engine, the ultrasonic vibrator is operated to atomize the fuel in the chamber, and both of the on-off valves are opened synchronously to release the atomized fuel. It is supplied to the intake passage as auxiliary fuel, while in operating conditions other than the specified operating conditions, both on-off valves are closed synchronously to seal the chamber, and the ultrasonic vibrator is operated intermittently (duty operation) at predetermined time intervals. ), the fuel is reliably atomized while consuming a small amount of electric power.

(Function) As a result, in an operating state in which the engine is not supplied with auxiliary fuel, both on-off valves close synchronously and the chamber is hermetically sealed. In this state, the required amount of atomized fuel is stored in the sealed chamber by the intermittent operation of the ultrasonic vibrator with a small amount of electric power.

When the engine shifts to a predetermined operating state in which auxiliary fuel should be supplied, both on-off valves open in synchronization, and this valve opening causes the atomized fuel stored in the chamber to be transferred to the downstream side of the chamber. The air is supplied to the intake passage at once by the suction by the intake negative pressure in the downstream intake passage and the pressure by the atmosphere in the upstream intake passage, and the response delay is eliminated.

(Effects of the invention) As described above, according to the invention, a chamber is provided in the intake passage of a diesel engine that communicates with the upstream and downstream opening/closing valves, and in an operating state in which auxiliary fuel is not supplied to the engine, Both open/close valves are closed synchronously to seal the chamber, and the ultrasonic vibrator is operated intermittently to reliably atomize the fuel in the chamber with small electric power, allowing the engine to operate at specified times when supplementary fuel is required. When the operating state is reached, both the on-off valves are opened synchronously and the atomized fuel in the chamber is supplied all at once to the intake passage as auxiliary fuel. By ensuring that the atomized fuel is quickly supplied when the engine transitions to the specified operating state, and delays in supply can be prevented, ultrasonic vibrations can be prevented in operating states other than when supplementary fuel is being supplied. By intermittent operation of the transducer, it is possible to miniaturize the ultrasonic transducer and reduce its power consumption.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 shows the overall configuration of a fuel supply system for a diesel engine according to an embodiment of the present invention, where 1 is a diesel engine, 2 is an intake passage for supplying intake air to the engine 1, and 3, 3, ... are engine engines. A fuel injection nozzle for injecting and supplying main fuel (light oil) to each cylinder combustion chamber of 1, and a fuel injection pump 4 driven by the engine 1 is installed in the fuel injection nozzle 3, 3, . . . The fuel injection pump 4 is connected via a fuel injection pipe 5, and the fuel suction port 4a of the fuel injection pump 4 communicates with a fuel tank 7 via a main fuel supply passage 6.
The fuel in the engine 1 is distributed under pressure and distributed to the fuel injection nozzles 3, 3, .

On the other hand, a bypass passage 8 that bypasses a part of the intake passage 2 is branched and connected to the intake passage 2, and a chamber 9 that can store fuel (light oil) is integrally formed at the bottom of the bypass passage 8. . Therefore, the chamber 9 is communicated with the intake passage 2 at two locations in the bypass passage 8: the upstream connection part 8a and the downstream connection part 8b. The chamber 9 has a float 10a for opening and closing the fuel inlet 9a.
The fuel inlet 9a is connected to the fuel tank 7 through an auxiliary fuel supply passage 12 in which a auxiliary fuel supply pump 11 driven by the engine 1 is interposed. There is.
Further, the fuel outlet 9b opened at the bottom of the chamber 9 is communicated with the fuel tank 7 via an auxiliary fuel return passage 14 having a leak valve 13 that closes when energized. The auxiliary fuel return passage 14 on the 7 side) and the auxiliary fuel supply passage 12 on the downstream side of the auxiliary fuel supply pump 11 (chamber 9 side) are communicated by an auxiliary fuel relief passage 15. supplies the fuel in the fuel tank 7 to the auxiliary fuel supply pump 1
1 into the chamber 9 and the chamber 9
A float valve 10 is used to maintain the liquid level at a constant level.

Further, ultrasonic transducers 16 and 1 are provided at the bottom of the chamber 9, that is, the part immersed in the stored fuel.
6 is attached, and the ultrasonic transducers 16, 16 are provided to vibrate in response to the output of an ultrasonic oscillator 17 that emits a predetermined ultrasonic frequency, and the ultrasonic transducers 16, 16 and the ultrasonic oscillator 17 constitutes a fuel atomization device 18 that atomizes the fuel within the chamber 9.

Further, at an upstream connecting portion 8a which is a connecting portion of the bypass passage 8 with the intake passage 2, a first opening/closing valve 19 for opening and closing the chamber 9 with respect to the intake passage 2 is provided.
However, similar second on-off valves 20 are provided in the downstream connection portion 8b, and the on-off valves 19, 20
is normally closed to cut off communication between the chamber 9 and the intake passage 2, and is opened when energized to allow the chamber 9 to communicate with the intake passage 2.

Furthermore, 21 is a lever opening sensor that detects the opening degree of the control lever 4b in the fuel injection pump 4, 22 is a rotation speed pickup that also detects the rotation speed of the engine 1 based on the rotation speed of the fuel injection pump 4, and 23 is the above-mentioned rotation speed pickup. Lever opening sensor 21
A control unit serves as a control device for controlling the operation of the leak valve 13, the ultrasonic oscillator 17, and both on-off valves 19 and 20 in response to the output from the rotation speed pickup 22.The control unit 23 is configured as follows. Has a control function. That is, based on the opening of the control lever 4b detected by the lever opening sensor 21 and the engine rotation speed detected by the rotation speed pickup 22, the engine 1 is in a high load operating state such as an accelerated operating state. (predetermined operating state in the present invention), and when the engine 1 is in a high-load operating state, a continuous operating signal is given to the ultrasonic oscillator 17 to continue the ultrasonic transducers 16, 16. and actuate (vibrate) the chamber 9.
Both the on-off valves 19 and 20 are opened in synchronization with each other so that the atomized fuel in the fuel injection pump 4 is supplied to the intake passage 2 as a sub-fuel different from the main fuel produced by the fuel injection pump 4. On the other hand, when the engine 1 is in a low-medium load operating state other than a high-load operating state, both on-off valves 19,
20 are closed in synchronization with each other to bring the chamber 9 into a sealed state, and a duty signal is given to the ultrasonic oscillator 17 to cause the ultrasonic vibrators 16, 16 to operate at predetermined time intervals so that the fuel in the chamber 9 is atomized. But it works intermittently. Further, while the engine 1 is operating, the leak valve 13 is always energized and controlled so as to close the leak valve 13.

Next, the operation of the above embodiment will be explained along the control flowchart shown in FIG. 2. After starting,
First, in step _S1, it is determined whether or not the engine 1 is in operation, and if this determination is NO because the engine 1 has stopped, the process moves to step _S2 , in which both the on-off valves 19 and 20 are synchronized. At the same time, the leak valve 13 is opened and the ultrasonic transducers 16, 16 are kept in a stopped state _.
Return to As a result, the fuel stored at the bottom of the chamber 9 during the previous operation of the engine 1 is returned to the fuel tank 7 through the auxiliary fuel return passage 14.

On the other hand, when the engine 1 is operated by injecting and supplying main fuel to the engine 1 by the fuel injection pump ₄ and the determination in step S1 is YES, the process moves to step _S3 and the leak valve 13 is closed. As a result, the fuel in the fuel tank 7 is pumped into the chamber 9 by the operation of the auxiliary fuel supply pump 11 driven by the engine 1, and is stored therein while maintaining a constant liquid level.

After this step _S3 , in step _S4 , the load signal of the engine 1 is read based on the engine speed and the opening degree of the control lever 4b of the fuel injection pump 4, and in the next step _S5 , the engine 1 is operated under high load. Determine whether the state is present or not. When this determination is NO due to the low-medium load operating state of the engine 1, both on-off valves 1 are turned off in step _S6 .
9 and 20 are synchronously closed to seal the chamber 9 to the intake passage 2, and in this state, the ultrasonic transducer 1
6 and 16 are operated intermittently at predetermined time intervals, the process returns to step S ₁ and the next steps S ₁ , S ₂ ,
…repeat.

In this way, the communication between the chamber 9 and the intake passage 2 is cut off, and intake air is not introduced into the chamber 9. Therefore, the ultrasonic transducer 1
6 and 16 are operated intermittently, the fuel stored at the bottom of the chamber 9 is constantly and reliably atomized without being subjected to intake pressure and floats in the upper space of the chamber 9. Due to this,
Atomized fuel is stored in the chamber 9.

Then, while repeating such a control flow, the engine 1 shifts to a high-load operating state _, and when the determination in step _S5 becomes YES, the process moves to step _S7 , in which both on-off valves 19, 20 are opened synchronously to open the chamber 9 to the intake passage 2, and the ultrasonic transducers 16, 16 are continuously operated, and then the process returns to step _S1 .

At this time, since the atomized fuel as described above is stored in the chamber 9 before being opened to the intake passage 2, the atomized fuel in the chamber 8 is stored in the on-off valve 19, 20 is opened and the chamber 9 is opened to the intake passage 2, and at the same time, the fuel is immediately supplied to the intake passage 2 on the downstream side of the chamber 9 as a part of auxiliary fuel different from the main fuel. That is, since both the on-off valves 19 and 20 open synchronously, the atomized fuel in the chamber 9 is not only sucked in by the negative intake pressure in the downstream intake passage 2, but also sucked in by the intake negative pressure in the upstream intake passage 2. It is pushed by the intake air and is supplied from the chamber 9 to the intake passage 2 in a short time. After this, when the engine 1 continues to operate under high load, the continuously operating ultrasonic transducer 16,
The fuel in the chamber 9 that has been atomized by the fuel pump 16 is subsequently supplied to the intake passage 2 as auxiliary fuel.

Therefore, when the engine 1 is in a low-medium load operating state, the sealed chamber 9
The ultrasonic transducers 16, 16 are operated intermittently within the
A necessary amount of atomized fuel is stored in the chamber 9 while consuming small electric power, and when the engine 1 shifts to a high-load operating state, the chamber 9 is opened to the intake passage 2 and the atomized fuel is stored in the chamber 9. In order to supply the atomized fuel stored in the chamber 9 to the intake passage 2 all at once as auxiliary fuel, the engine 1 shifts to a high-load operating state by quickly supplying the atomized fuel stored in the chamber 9 to the intake passage 2. In addition, it is possible to prevent delays in the supply of atomized fuel when the ultrasonic vibrator 1
By intermittent operation of the ultrasonic transducers 6 and 16, it is possible to downsize the ultrasonic transducers 16 and 16 and reduce their power consumption while ensuring atomization of the fuel.

In addition, in the above embodiment, the ultrasonic transducers 16, 16
Although the predetermined operating state of the engine 1 that supplies the auxiliary fuel atomized in the chamber 9 to the intake passage 2 through intermittent operation is a high-load operating state, it goes without saying that the operating state may be changed to another operating state. stomach.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is an overall configuration diagram, and FIG. 2 is a flowchart showing the flow of the control system. 1... Diesel engine, 2... Intake passage, 4...
Fuel injection pump, 4b...control lever, 7
...Fuel tank, 8...Bypass passage, 8a...Upstream side connection part, 8b...Downstream side connection part, 9...Chamber, 1
1...Auxiliary fuel supply pump, 13...Leak valve, 1
6... Ultrasonic transducer, 17... Ultrasonic oscillator, 18...
Fuel atomization device, 19...first on-off valve, 20...second
Opening/closing valve, 21... Lever opening sensor, 22... Rotation speed pickup, 23... Control unit.

Claims (1)

[Scope of claim for utility model registration] Separately from the main fuel under the specified operating conditions of the engine,
In a fuel supply system for a diesel engine, which supplies auxiliary fuel atomized by a fuel atomizer having an ultrasonic vibrator to an intake passage, the intake passage communicates with the intake passage at upstream and downstream connections, respectively. An ultrasonic vibrator is installed in the chamber in which fuel is stored, and opening/closing valves are installed at the upstream and downstream connections to open and close the chamber with respect to the intake passage. At the same time, both on-off valves are opened synchronously so that the atomized auxiliary fuel in the chamber is supplied to the intake passage, while in operating states other than the specified operating state, both on-off valves are opened synchronously. 1. A fuel supply device for a diesel engine, comprising a control device for controlling an ultrasonic vibrator to operate intermittently at predetermined time intervals so that the fuel in the chamber is atomized when the chamber is closed.