JPH0220455Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to a fuel supply device for a diesel engine, and in particular, the present invention is directed to a fuel supply system for a diesel engine, and in particular, it supplies an auxiliary fuel that is atomized by an ultrasonic vibrator in addition to the main fuel to the engine. This invention relates to an improvement in the air supply to the 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 have been disclosed, for example, in Japanese Patent Application Laid-Open No. 52-112018. As shown in the figure, the fuel supplied from the 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, we have proposed a system that reduces fuel adhesion to the walls of the intake passage compared to carburetor systems, fuel injection systems, etc., and improves the accuracy of the air-fuel ratio. has been done.

On the other hand, in a diesel engine, the main fuel is fuel that is directly injected into the combustion 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 combustion 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.

Therefore, it is conceivable to atomize light oil using an ultrasonic vibrator using the concept in the above proposed example, and to supply the atomized light oil to the intake passage of a diesel engine as an auxiliary fuel.

However, when light oil is used as an auxiliary fuel to be atomized by an ultrasonic vibrator, since the light oil is composed of various components with various carbon numbers, it is necessary to use a single ultrasonic vibrator. When the light oil is vibrated at a frequency of , a problem arises in that the composition of the auxiliary fuel supplied to the intake passage changes.

(Purpose of the invention) The purpose of the invention is to reduce the vibration frequency of the ultrasonic vibrator when supplying light oil in the chamber atomized by the ultrasonic vibrator to the intake passage of a diesel engine as an auxiliary fuel as described above. By setting a plurality of values, it is possible to prevent only a specific component of the light oil from being atomized and to keep the composition of the auxiliary fuel supplied to the intake passage stable and appropriate.

(Structure of the invention) In order to achieve the above object, the structure of the invention is as follows:
An ultrasonic vibrator is installed in a chamber that communicates with the intake passage of a diesel engine and stores light oil as an auxiliary fuel for the engine.
It is connected to an ultrasonic oscillator that emits at least two different frequencies within the range of 0.8 to 2.4 MHz. That is, a plurality of ultrasonic transducers are arranged in a chamber, and each of the ultrasonic transducers is connected to a plurality of mutually independent ultrasonic oscillators that emit different frequencies, or an ultrasonic vibration is arranged in a chamber. The ultrasonic transducer is connected to one ultrasonic oscillator that emits different frequencies. This allows the ultrasonic vibrator to vibrate at a plurality of frequencies depending on each component of light oil.

(Effect of the invention) Therefore, according to the invention, light oil is atomized by vibrating two or more types of ultrasonic vibrators at different frequencies in a chamber that stores light oil as an auxiliary fuel for a diesel engine. Therefore, it is possible to prevent only specific components of the light oil from being atomized and supplied to the intake passage, thereby making it possible to stabilize and optimize the composition of the auxiliary fuel of the diesel engine.

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

FIG. 1 shows the overall configuration of a diesel engine fuel supply system according to a first embodiment of the present invention, in which 1 is a diesel engine, 2 is an intake passage for supplying intake air to the engine 1, 3, 3, . . . is a fuel injection nozzle for injecting and supplying main fuel (light oil) to each cylinder combustion chamber of the engine 1, and the fuel injection nozzles 3, 3, . . . are equipped with a fuel injection pump driven by the engine 1. 4 is connected via a fuel injection pipe 5, and a 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 inside is distributed under pressure to the fuel injection nozzles 3, 3, . . . and injected as the main fuel into each combustion chamber of the engine 1 from 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 light oil as an auxiliary fuel is integrally formed at the bottom of the bypass passage 8. Therefore, the chamber 9 communicates with the intake passage 2 at two points. The chamber 9 has its fuel inlet 9
A float valve 10 having a float 10a that opens and closes a is integrally formed, and the fuel inlet 9a is connected to an auxiliary fuel supply pump 1 driven by the engine 1.
The fuel tank 7 is connected to the fuel tank 7 through an auxiliary fuel supply passage 12 with a fuel supply passage 1 interposed therebetween. In addition, the above chamber 9
A fuel outlet 9b opened at the bottom of the fuel tank 7 is communicated with the fuel tank 7 via an auxiliary fuel return passage 14 having a leak valve 13 that closes when energized, and the auxiliary fuel on the downstream side (fuel tank 7 side) of the leak valve 13 is connected to the fuel tank 7. The return passage 14 and the auxiliary fuel supply passage 12 on the downstream side (chamber 9 side) of the auxiliary fuel supply pump 11 are communicated with each other by an auxiliary fuel relief passage 15. Fuel (light oil) is pumped into the chamber 9 by an auxiliary fuel supply pump 11 and stored therein while being maintained at a constant liquid level by a float valve 10.

Further, three ultrasonic transducers 16a to 16c are attached to the bottom of the chamber 9, that is, the part immersed in the stored fuel (light oil), and the ultrasonic transducers 16a to 16c each have a predetermined type of ultrasonic frequency ( For example, the ultrasonic vibrator 16 is provided to vibrate in response to the output of ultrasonic oscillators 17a to 17c that emit 1.0MHz, 1.8MHz, 2.2MHz).
A to 16c and ultrasonic oscillators 17a to 17c constitute a fuel atomization device 18 that atomizes the fuel in the chamber 9.

Furthermore, two electromagnetic on-off valves 19 and 20, a first and a second electromagnetic valve, for opening and closing the chamber 9 synchronously with respect to the intake passage 2 are disposed in the bypass passage 8 at a connection portion with the intake passage 2; Both on-off valves 19, 2
0 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
In response to the output from the rotation speed pickup 22, the leak valve 13 and the ultrasonic oscillator 17a~
17c and both on-off valves 19 and 20, the control unit 23 has the following control functions. That is, the control lever 4 detected by the lever opening sensor 21
It is determined whether or not the engine 1 is in a high-load operating state, for example, based on the opening degree of the opening 2 and the engine speed detected by the rotational speed pickup 22, and when the engine 1 is in a high-load operating state, An operating signal is given to the ultrasonic oscillators 17a to 17c to sequentially operate (vibrate) the ultrasonic vibrators 16a to 16c, and both on-off valves 19 and 20 are opened to transfer the atomized fuel in the chamber 9 to the fuel injection pump 4. The fuel is supplied to the intake passage 2 as an auxiliary fuel different from the main fuel. 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 1
9 and 20 to bring the chamber 9 into a sealed state, and at the same time, the ultrasonic transducers 16a to 16c are deactivated. Further, while the engine 1 is operating, the leak valve 13 is always energized to close the leak valve 13.

Therefore, in the above embodiment, when the operation of the engine 1 is stopped, both the on-off valves 19 and 20 are opened by the operation of the control unit 23.
is closed, the leak valve 13 is opened, and the ultrasonic transducers 16a to 16c are kept inactive. As a result, the previous engine 1
During operation, the fuel (light oil) stored at the bottom of the chamber 9 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, the leak valve 13 is closed, which causes the auxiliary fuel supply pump 11 driven by the engine 1 to Upon operation, the fuel (light oil) in the fuel tank 7 is pumped and stored in the chamber 9 while maintaining a constant liquid level. Simultaneously with the closing operation of the leak valve 13, the load state of the engine 1 is determined based on the engine speed and the opening degree of the control lever 4b of the fuel injection pump 4. Both on-off valves 19 and 20 are closed and the chamber 9
is sealed from the intake passage 2, and the ultrasonic transducers 16a to 16c are kept inactive. As a result, intake air (air) is supplied to the engine 1 through the intake passage 2 as usual.

Then, when the engine 1 shifts from the low-medium load operating state to the high-load operating state, both on-off valves 19 and 20
is opened to open the chamber 9 to the intake passage 2, and the ultrasonic transducers 16a to 16c are sequentially activated. The light oil in the chamber 9 is atomized by the operation of the ultrasonic transducers 16a to 16c, and the atomized light oil is supplied from the open chamber 9 to the intake passage 2 as an auxiliary fuel. The ignitability and fuel properties of the fuel are improved, improving engine output and reducing smoke generation.

In that case, three ultrasonic vibrators 16 each vibrating at different frequencies are installed in the chamber 9 storing light oil.
a to 16c are arranged, and the ultrasonic transducers 16a to
As the light oil becomes finely densified by the operation of 16c,
Each component of the light oil is evenly atomized, and only a specific component can be prevented from being atomized, so that the composition of the auxiliary fuel supplied to the engine 1 can be kept stable and appropriate.

In addition, the three ultrasonic transducers 16a to 16c
Since the ultrasonic transducers 16a to 16c are operated separately in sequence, it is possible to prevent the frequencies from the ultrasonic transducers 16a to 16c from interfering with each other, which would occur if they were operated at the same time, thereby ensuring uniform atomization of each component of light oil. This can be further promoted.

FIG. 2 shows a second embodiment of the present invention (in addition, the first embodiment
The same parts as those in the figures are given the same reference numerals and detailed explanation thereof is omitted), and the number of ultrasonic transducers 16' disposed in the chamber 9 is one.

That is, in this embodiment, one ultrasonic transducer 16' disposed in the chamber 9 includes one oscillation coil L, three capacitors C ₁ to _{C 3} each having a different predetermined capacitance. , electromagnetic relays R ₁ to _{R 3} which receive electricity from the control unit 23 and form an oscillation circuit by the oscillation coil L and one of the capacitors C ₁ to C ₃ , and a generator driven by the engine 1. An ultrasonic oscillator 17' comprising a bridge type rectifier circuit B that rectifies the output voltage from (not shown) and supplies it to the oscillation circuit.
By sequentially switching and using the capacitors C ₁ to _{C 3} in the ultrasonic oscillator 17', the ultrasonic vibrator 16' is vibrated at three different frequencies, and the light oil (secondary oil) in the chamber 9 is vibrated at three different frequencies. fuel). Therefore, this embodiment has the advantage that the required number of ultrasonic transducers 16' can be reduced compared to the first embodiment.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is an overall configuration diagram showing the first embodiment, and FIG. 2 is an electric circuit diagram of an ultrasonic oscillation device in the second embodiment. 1... Diesel engine, 2... Intake passage,
4...Fuel injection pump, 4b...Control lever, 7...Fuel tank, 9...Chamber, 11
...Auxiliary fuel supply pump, 13...Leak valve,
16a-16c, 16'... Ultrasonic transducer, 17
a~17c, 17'... Ultrasonic oscillator, 18...
Fuel atomization device, 19...first on-off valve, 20...
Second on-off valve, 21... Lever opening sensor, 22...
...Rotational speed pickup, 23...Control unit.

Claims (1)

[Scope of utility model registration request] In a fuel supply system for a diesel engine that supplies an auxiliary fuel atomized by a fuel atomizer having an ultrasonic vibrator to the intake passage in addition to the main fuel, light oil is used as an auxiliary fuel in communication with the intake passage. 1. A fuel supply system for a diesel engine, characterized in that an ultrasonic vibrator is disposed in a chamber in which the ultrasonic vibrator is stored, and the ultrasonic vibrator is connected to an oscillation device that emits at least two or more different frequencies.