JPH0299760A - Fuel injector for internal combustion engine - Google Patents

Abstract

PURPOSE:To prevent fuel from being left in an injection chamber by completing the fuel/air injection control by the injection action of the compressed air on the engine stop. CONSTITUTION:During the engine operation, a fuel injection valve 36 is opened at a prescribed crank angle, and jets fuel into a compressed air flow-out passage 35 and a needle insertion hole 22. Then, the solenoid 30 of an air blast valve 20 is put into electric conduction, and a needle 23 opens a nozzle port 24, and fuel and the compressed air are jetted into a combustion chamber 4 from the nozzle port 24. When an ignition switch is turned OFF by the closing of the fuel injection valve 36 during the engine stop, the solenoid 30 is turned ON during the time determined from the electric discharge time constant of a condenser, and fuel and air are jetted into the combustion chamber 4 from the nozzle port 24. Therefore, in the engine starts at the next time, the troubles of metering fuel again and the generation of overrich state can be obviated, and since no fuel is left in the needle insertion hole, etc., the adhesion of carbon and deposits can be prevented.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a fuel injection device for an internal combustion engine.

[Conventional technology]

Japanese Patent Publication No. 60-501963 discloses that a nozzle port is formed at one end of an injection chamber, a compressed air passage is communicated with the other end, and a fuel supply passage is communicated between one end of the injection chamber and the other end. , a solenoid valve is provided at the nozzle port, which is normally biased by a spring in the valve closing direction and is opened by energizing the solenoid;
At the same time as this solenoid valve is opened, the fuel supplied from the fuel supply passage into the injection chamber is transferred from the compressed air passage into the injection chamber (J). An injector is disclosed.

In this fuel injection device, when the solenoid valve is opened, compressed air flows inside the injection chamber, and the fuel adhering to the inner wall surface of the injection chamber can be transported and expanded by the compressed air.

On the other hand, JP-A-62-31 [118] discloses that a nozzle port formed at one end of the injection chamber is provided with automatic opening/closing, and a fuel injection port/l valve and an air injection valve are provided facing the injection chamber. After injecting fuel into the injection chamber from the fuel injection valve, compressed air is injected into the injection chamber from the air injection valve, and the fuel is injected from the nozzle [1] by the compressed air. [An injection device is disclosed.

[Problems to be Solved by the Invention] However, in such a conventional fuel injection device, if the ignition switch is turned off immediately after injecting fuel into the injection chamber or during fuel supply, the fuel will be discharged from the nozzle port following fuel injection. Since no air injection is performed, there is a problem in that the fuel in the injection chamber is not injected from the nozzle 1 by compressed air and remains in the injection chamber.

If fuel remains in the injection chamber, the next time you start the engine,
Since the fuel is metered again and the metered fuel is supplied into the combustion chamber, the accuracy of the amount of fuel supplied at the time of startup is reduced, resulting in over-rich condition. Additionally, fuel remaining near the nozzle opening causes carbon and deposits to adhere due to engine heat.

[Means to solve the problem]

In order to solve the above problems, according to the present invention, fuel is supplied into a compressed air passage having a nozzle opening formed at its tip, and then the compressed air supplied into the compressed air passage is injected together with fuel from the nozzle opening. In a fuel injection device that controls fuel-air injection by alternately repeating fuel supply and compressed air injection during engine operation, when the engine is stopped, fuel-air injection is controlled by compressed air injection. I am trying to complete it.

[For production]

According to the above-described structure, the present invention completes the fuel-air injection control by the injection action of compressed air when the engine is stopped, so that the fuel supplied to the compressed air passage is injected from the nozzle port by the compressed air. You will be forced to do so.

〔Example〕

Referring to Figures 2 and 3, ■ is the cylinder block, 2 is the screw 1, 3 is the cylinder head, 4 is the combustion chamber,
Reference numeral 5 indicates a pair of air supply valves, 6 indicates an air supply valve, 1-17 indicates a pair of exhaust valves, 8 indicates an exhaust port, and 9 indicates a spark plug. A mask wall 10 is formed on the inner wall surface of the cylinder head 3 to close an opening between the peripheral edge of the air intake valve 5 on the exhaust valve 7 side and the valve seat during the full opening period of the air intake valve 5. Therefore, when the intake valve 5 opens, fresh air flows into the combustion chamber 4 from the side opposite to the exhaust valve 7 as shown by arrow A. On the inner wall surface of the cylinder head 3 located between the pair of air supply valves 5 is an air plus 1 valve 20.
is placed.

FIG. 4 shows a partially sectional side view of the air blast valve 20.

Referring to FIG. 4, a straight needle insertion hole 22 is formed in the housing 21 of the air blast valve 20, and a needle 23 having a smaller diameter than the needle insertion hole 22 is inserted into the needle insertion hole 22. A nozzle port 24 is formed at one end of the needle insertion hole 22, and this nozzle port 24 is connected to a valve portion 25 formed at the tip of the needle 23.
Opening/closing is controlled by In the embodiment shown in FIG. 4, this nozzle [lI] 24 is arranged within the combustion chamber 4. In the embodiment shown in FIG. Further, a spring retainer 26 is fixed to the needle 23, and a compression spring 27 is inserted between the spring retainer 26 and the housing 21.

Due to the spring force of the compression spring 27, the nozzle port 24 is normally closed by the valve portion 25 of the needle 23.

A movable core 2 is provided at the end of the needle 23 opposite to the valve portion 25.
8 are always brought into contact with each other by the spring force of a compression spring 29, and a solenoid 30 and a stator 31 for attracting the movable core 28 are arranged within the housing 21. When the solenoid 30 is energized, the movable core 28 moves toward the stator 3.
As a result, the needle 23 moves in the direction of the nozzle opening 24 against the spring force of the compression spring 27, so that the nozzle opening 24 is opened.

On the other hand, inside the housing 21 is a cylindrical nozzle chamber 32.
is formed. One end 32a of the nozzle chamber 32 is communicated with the compressed air inflow passage 33, and the other end 32a of the nozzle chamber 32 is connected to the compressed air inflow passage 33.
b is connected to the needle insertion hole 22 via the compressed air outflow passage 35.
communicated within.

A jet 137 of the fuel injection valve 36 is disposed in the nozzle chamber 32, and the jet port 37 is connected to one end 32a of the nozzle chamber 32.
and the other end 32b. As shown in FIG. 4, the compressed air outflow passage 35 extends straight. The nozzle 37 is arranged on the axis of the compressed air outflow passage 35, and fuel with a small spreading angle is injected from the nozzle 37 along the axis of the compressed air outflow passage 35. The compressed air outflow passage 35 extends obliquely to the needle insertion hole 22 in the direction of the nozzle opening 24, and is connected to the needle insertion hole 22 at an angle of 20 degrees to 45 degrees to the needle insertion hole 22. .

FIG. 5 shows an overall configuration diagram of this embodiment. Referring to FIG. 5, 40 is an intake manifold, 41 is a surge tank, 42 is an air cleaner, and 43 is an air supply pipe connecting the surge tank 41 and the air cleaner 42, respectively. In the middle of the air supply pipe 43, air flow meters 4 are installed sequentially from the upstream side.
4, a throttle valve 45 and a mechanical supercharger 46 are provided.

A conduit 47 is branched from the air supply pipe 43 between the air cleaner 42 and the air flow meter 44, and this conduit 47 is connected to the suction port 48a of the near compressor 48. On the other hand, the discharge port 48b of the near compressor 48 is connected to the compressed air inflow passage 33. A pressure regulator 49 is provided in the middle of the compressed air inflow passage 33, and the pressure regulator 49 is connected to a return pipe 50.
is connected to the air supply pipe 43 between the opening of the conduit 47 to the air supply pipe 43 and the air flow meter 44 .

51 is a fuel air injection control device, 52 is a crank angle sensor that generates an output pulse proportional to the engine speed, 53 is an ignition switch, and 54 is a crank reference position sensor that generates an output pulse at every dead center. show.

Referring again to FIG. 4, the needle insertion hole 22 and the nozzle chamber 3
2 and the compressed air outflow passage 35 are the compressed air inflow passage 33
It communicates with a near compressor 48 (see FIG. 5) via a. Therefore, these needle insertion holes 22 and nozzle chambers 3
2 and the compressed air outflow passage 35 are filled with compressed air. Fuel is injected into this compressed air from the nozzle 37 along the axis of the compressed air outflow passage 35. As shown in FIG. 4, the compressed air outlet passage 35 connects to the needle insertion hole 22.
Most of the injected fuel is connected diagonally to the valve part 2.
5 reaches into the needle insertion hole 22 around the needle 23. At this time, some of the fuel adheres to the inner wall surface of the compressed air outflow passage 35 and the inner wall surface of the nozzle chamber 32. Next, when the solenoid 30 is energized, the needle 23 opens the nozzle port 24. At this time, since the injected fuel is gathered near the valve part 25, as soon as the needle 23 opens the nozzle port 24, both the fuel and compressed air are released from the nozzle port 24 into the combustion chamber 4.
Squirt inside. Further, when the needle 23 opens the nozzle port 24 , compressed air flows into the nozzle chamber 32 from the compressed air inflow passage 33 , and then goes to the nozzle port 24 via the compressed air outflow passage 35 . The fuel adhering to the inner wall surface and the inner wall surface -F of the nozzle chamber 32 is carried away by the compressed air flow and is ejected from the nozzle 24. Therefore, as soon as the needle 23 opens, all of the injected fuel is injected from the nozzle port 24, and then only compressed air is injected from the nozzle port 24 when the injection of all the injected fuel is completed. Then, the solenoid 30 is deenergized and the needle 23 closes the nozzle port 24. Therefore, just before the needle 23 is closed, only air is ejected from the nozzle port 24.

FIG. 1 shows a configuration diagram of the fuel air injection control device 5I.

Referring to FIG. 1, the fuel/air injection control device 51 includes an electronic control unit 60 and a control circuit 70. As shown in FIG.

The electronic control unit 60 consists of a digital computer, and is connected to a bidirectional lotus 61 with ROs connected to each other.
M (read only memory) 62, RAM (random access memory) 6 (], CI]t, J (microprocessor) 64, input port 5 and output port G (+f&).

The control circuit 70 includes an external memory 71 for storing a flag F to be described later, a NOT element 80, and an AND element 72.
, a drive circuit 73 , and a transistor 77 .

The human powered port 5 is connected to the air flow meter 44 via an A/D converter 74. The input port is also connected to a crank angle sensor 52, an ignition switch 53, and a crank lrlζ position sensor 54. On the other hand, the output port 6 is connected to the base of a transistor 77 and the fuel injection valve 36 via drive circuits 75 and 76. Battery 7 is connected to the collector of transistor 77 via resistor 79 and solenoid 30 of air blast valve 20. Further, the battery 78 is connected to -U A via the ignition switch 53 and the NOT element 80.
N I) Connected to one of the input terminals of element 72.

The other input terminal of AND element 'I 2 is external memory 71
connected to the output boat via. Further, the output terminal of the A N 1) element 72 is connected to the base of the 1-hylang resistor 77 via the drive circuit 73 .

The moving object of this embodiment will be explained with reference to FIGS. 6 and 7. Referring to FIG. 6, during engine operation, the fuel injection valve 36 is opened at a predetermined crank angle θ, and fuel is injected into the compressed air outflow passage 35 and the needle insertion hole 22. At the same time, flag F is set to l and stored in external memory 71. θ2
At this point, the fuel injection valve 36 is closed, and fuel injection ends. Subsequently, at θ3, a base current is caused to flow from the drive circuit 75 to the transistor 77, and the transistor 77 is turned on. This energizes the solenoid 30, causing the needle 23 to open the nozzle port 24. Therefore, both fuel and compressed air are ejected from the nozzle port 24 into the combustion chamber 4. Next, at θ4, the drive circuit 75 drives the transistor 7.
7 is turned off, the solenoid 30 is de-energized, and the needle 23 closes the nozzle port 24. At this time, flag F is reset to O. The above operation is executed every revolution of the piston 2. Note that when the engine is running, the ignition switch 53 is always on, so the N
Since the signal inverted by the OT element 80 and input to the AND element 72 is an O level signal, the output of the AND element 72 is always a 0 level signal. Therefore, the drive circuit 73 does not turn on the transistor 77.

Next, the operation when the engine is stopped will be explained with reference to FIG. At the crank angle θ, the fuel injection valve 36 is opened -U and fuel injection is started. At this time, flag F is set to 1, and 1 is set in external memory 71. When the ignition switch 53 is turned off at θ6 during the fuel injection period, the electronic control unit 60 is turned off and the fuel injection valve 36 is closed. At this time, l is maintained in the external memory 71 and C is maintained. - When the ignition switch 53 is turned off, the signal input from the NOT element 80 to the AND element 72 becomes a l level signal. For this reason, AND
A level signal is output from the element 72 to drive the drive circuit 73. The drive circuit 73 flows, for example, the discharge current of the capacitor into the base of the transistor 77 for a time determined by the time constant of the discharge circuit, for example, one second. This results in 1-
The lungstuff 7 is turned on for one second, and the solenoid 3° is turned on, so that both fuel and air are jetted from the nozzle port 24 into the combustion chamber 4. Flag F
is not set at this time, and when starting the engine next time,
It is initialized and reset to 0 when the electronic control unit 6o is turned on.

In this embodiment, only when the ignition switch 53 is off and 1 is stored in the external memory 71, the AND element 72 outputs a reher signal, the needle 23 opens the nozzle port 24, and the fuel is released together with air. She is made to squirt.

Therefore, when the flag F is reset to 0, the period from when the solenoid 30 of the Zunawara airplast valve 20 is turned off until the next time when the fuel injection valve 36 is opened (
Even if the ignition switch 53 is turned off during the period from θ to θ,′ in FIG. 6, the nozzle port 24 is not opened. In this case, all the fuel is injected from the nozzle port 24 by the injection action of the compressed air, and no fuel remains in the compressed air outflow passage 35, needle insertion hole 22, etc.

As described above, according to this embodiment, when the ignition switch 53 is turned off, if the fuel injected from the fuel injection valve 36 remains in the needle insertion hole 22, etc., the solenoid I''30 is activated. to open the nozzle port 24,
The residual fuel is injected from the nozzle port 24 by compressed air. Therefore, when the ignition switch 53 is turned off, no fuel remains in the needle insertion hole or the like. For this reason,
When the engine is started next time, there is no risk that the fuel will be measured again and the amount of fuel injected from the nozzle port 24 will increase, resulting in over-rich condition. In addition, there is no fuel inside the needle insertion hole 22, etc.
Since at does not remain, it does not cause the adhesion of carbon or deposits.

FIG. 8 shows a routine for executing fuel air injection control during engine operation. This routine is interrupted every time the crank reaches top dead center.

First, in step 100, Q/N is calculated from the intake air IQ detected by the air flow meter 44 and the engine rotation speed N detected by the crank angle sensor 52. Q
/N corresponds to the engine load.

In step 101, a basic fuel injection time [P] is obtained from a two-dimensional map of Q/N and N, and this is multiplied by a correction coefficient to calculate a fuel injection time TAU. In step 102,
The fuel injection start crank angle θ is calculated from the TAU and the fuel injection end crank angle θ2 (see FIG. 9). Here, θ2 is a fixed crank angle. In step 103, the crank angle θ is θ.

It is determined whether the Crank angle θ is θ.

When this happens, the process proceeds to step 104, where the fuel injection valve 36 is opened and fuel injection is started. At step 105, flag F is set to 1. In step 106, it is determined whether the crank angle θ has reached θ7 (see FIG. 9). When θ reaches θ2, the process proceeds to step 107, where the fuel injection valve 36 is closed and fuel injection is completed. In step 108, it is determined whether 0 has become 04 (9th
(See figure) When 9θ becomes θ□, the process proceeds to step 109 and the solenoid 30 is turned on. As a result, fuel and air are injected into the combustion chamber 4 from the nozzle port 24. In step 110, it is determined whether θ has become θ4 (9th
(see figure). When θ reaches θ4, the process proceeds to step III, where the solenoid 30 is turned off. As a result, the nozzle port 24 is closed by the needle 23. At step 112, flag F is reset to O.

FIG. 10 shows a second embodiment. With reference to FIG.
to one input terminal of A, and the other to one input terminal of A
It is connected to the other input terminal of the ND element 121. AND
The output terminal of element 121 is connected to one of the input terminals of OR element 123.

The other input terminal of the OR element 123 is connected to the electronic control unit 6
Connected to 0. The output terminal of the OR element 123 is connected to the solenoid 30 (
(see Figure 4). The fuel injection valve 36 is connected to an electronic control unit 60 .

The electronic control unit 60 also includes an air flow meter 44,
A crank angle sensor 52, an ignition switch 53, and a crank reference position sensor 54 are connected.

The operation of this embodiment is basically the same as that of the first embodiment,
The operation of this embodiment will be explained with reference to FIGS. 6 and 7. During engine operation, the fuel injection valve 36 is opened at a predetermined crank angle θ1 and closed at a predetermined crank angle θ2. Subsequently, at θ, a solenoid activation signal is sent from the electronic control unit 60, and this signal is applied to the OR element 123.
The signal is input to the drive circuit 124 via. by this,
Solenoid 30 (see Figure 4) is energized and needle 2
3 opens the nozzle port 24. At this time, both fuel and compressed air are ejected from the nozzle port 24 into the combustion chamber 4. Subsequently, at θ4, a solenoid energizing signal is sent from the electronic control unit 60 to the drive circuit 124 via the OR gate 123.
will be sent to. This deenergizes the solenoid 30 and causes the needle 23 to close the nozzle port 24. In addition, when the engine is running, the ignition switch (, 7ch 53
is always on, so it is inverted by the NO'1' element 120. (The signal input to the AND element 121 is an O level signal, so the output of the AND element is always a 0 level signal. During operation, AND element 1
Depending on the output signal of 21, solenoid 30 is not energized.

When the engine is stopped, the fuel injection valve 3 is closed at the crank angle θ5.
6 is opened. When the ignition switch 53 is turned off at θ during the fuel injection period, the electronic control unit 60 is turned off and the fuel injection valve 36 is closed. When the ignition switch 53 is turned off,
The signal input from the NOT element 120 to the AND element 121 becomes 1. On the other hand, the signal input to the AND element 121 via the delay circuit 122 maintains 1 only during the delay time of the delay circuit. Therefore, one signal is output from the AND element 121 and passed through the OR element 123 to the drive circuit 124.
is input. This causes the drive circuit 124 to energize the solenoid 30, causing the needle 23 to open the nozzle port 24 for a delay time, for example, one second. At this time, compressed air is ejected from the nozzle port 24, and the residual fuel is ejected from the nozzle port 24 into the combustion chamber 4 together with this compressed air.

In this embodiment, the solenoid 30 is energized to open the nozzle port 24 regardless of whether the fuel injected from the fuel injection valve 36 remains in the needle insertion hole 22 or the like. It blows out compressed air. That is, in this embodiment, the ignition switch 5
Regardless of the timing at which the ignition switch 3 is turned off, compressed air is always injected from the nozzle port 24 only during the delay time of the delay circuit 122 when the ignition switch is turned off.

Therefore, in this embodiment, the same effects as in the first embodiment can be achieved without using the flag F in the first embodiment.

In the above-described embodiment, a fuel injection device having a solenoid valve at the nozzle opening that is opened by energizing the solenoid was described, but a fuel injection device having an air injection valve,
The present invention can also be applied to a fuel injection device having an automatic opening/closing valve at the nozzle port that is opened by the pressure of compressed air injected from an air injection valve.

〔Effect of the invention〕

As described above, according to the present invention, when the engine is stopped, the fuel supplied into the compressed air passage is always injected from the nozzle port by compressed air, so that no fuel remains in the compressed air passage. . Therefore, the next time the engine is started, the accuracy of the amount of fuel injected from the nozzle will not decrease.

4. Explanation of cross-section nodes FIG. 1 is a configuration diagram of the fuel air injection control device according to the first embodiment of the present invention, FIG. 2 is a bottom view of the inner wall surface of the cylinder head, and FIG.
The figure is a sectional side view of a two-cycle engine, FIG. 4 is a partial sectional side view of an air blast valve, FIG. 5 is an overall configuration diagram of the first embodiment, and FIGS. 6 and 7 are of the first embodiment. 6 is a diagram showing the operation when the engine is running, FIG. 7 is a diagram when the engine is stopped, FIG. 8 is a flowchart for executing fuel air injection control, and FIG. 9 is a diagram showing the fuel injection period, etc. FIG. 10 is a main configuration diagram of the second embodiment.

20... Air blast valve, 22... Needle insertion hole, 23... Needle, 24... Nozzle port,
30... Solenoid, 32... Nozzle chamber, 3
5... Compressed air outflow passage, 36... Fuel injection valve, 51... Fuel air injection control device, 53... Ignition switch, 60... Electronic control unit, 70... Control circuit.

Claims (1)

[Claims] After supplying fuel into a compressed air passageway having a nozzle port formed at its tip, the compressed air supplied into the compressed air passageway is injected together with the fuel from the nozzle port, and the fuel is supplied and compressed during engine operation. A fuel injection device for an internal combustion engine that controls fuel-air injection by alternately repeating an injection action of air, and completes the fuel-air injection control with an injection action of compressed air when the engine is stopped. .