JP2586602B2 - Fuel injection device for internal combustion engine - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fuel injection device for an internal combustion engine.

[Conventional technology]

JP-T-60-501963 discloses that a nozzle port is formed at one end of an injection chamber, a compressed air passage is communicated at the other end, and a fuel supply passage is communicated between one end and the other end of the injection chamber. A solenoid valve that is spring-biased in the normally closed direction and is opened by energizing the solenoid is provided at the nozzle port. There is disclosed a fuel injection device in which compressed air supplied from a compressed air passage into an injection chamber is injected from a nozzle port.

In this fuel injection device, when the solenoid valve opens, the compressed air flows through the injection chamber, and the fuel adhering to the inner wall surface of the injection chamber can be carried away by the compressed air.

On the other hand, Japanese Patent Application Laid-Open No. Sho 62-3168 discloses that a fuel injection valve and an air injection valve are provided at a nozzle opening formed at one end of an injection chamber, and a fuel injection valve and an air injection valve are arranged facing the injection chamber. A fuel injection device has been disclosed in which fuel is injected into an injection chamber from an air injection valve, and then compressed air is injected into the injection chamber from an air injection valve, so that the fuel is injected from a nozzle port by the compressed air.

[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, for example, air injection from the nozzle port subsequent to fuel injection is not performed. There is a problem that the fuel in the chamber is not injected from the nozzle port by the compressed air, but remains in the injection chamber.

If the fuel remains in the injection chamber, the next time the engine is started, the fuel is measured again and the measured fuel is supplied into the fuel chamber. Become. Further, fuel remaining near the nozzle opening causes carbon and deposits to adhere due to the heat of the engine.

[Means for solving the problem]

According to the present invention, in order to solve the above-described problems, after supplying fuel into a compressed air passage having a nozzle port formed at a tip, the compressed air supplied into the compressed air passage is injected together with fuel from the nozzle port. In other words, in the fuel injection device in which the fuel supply and the compressed air injection action are alternately repeated during the operation of the engine to control the fuel air injection, when the engine is stopped, the fuel air injection action is performed by the compressed air injection action. The control is completed.

[Action]

According to the present invention, when the engine is stopped, the fuel air injection control is completed by the compressed air injection action when the engine is stopped, so that the fuel supplied into the compressed air passage is injected from the nozzle port by the compressed air. You will be swayed.

〔Example〕

2 and 3, 1 is a cylinder block, 2 is a piston, 3 is a cylinder head, 4 is a combustion chamber, 5 is a pair of supply valves, 6 is a supply port, and 7 is a pair of exhaust valves. , 8 denotes an exhaust port, and 9 denotes a spark plug. A mask wall 10 is formed on the inner wall surface of the cylinder head 3 so as to close the opening between the peripheral portion of the supply valve 5 on the exhaust valve 7 side and the valve seat during the full opening period of the supply valve 5. Therefore, when the air supply valve 5 is opened, fresh air flows into the combustion chamber 4 from the side opposite to the exhaust valve 7 as shown by an arrow A. An air blast valve 20 is arranged on the inner wall surface of the cylinder head 3 located between the pair of air supply valves 5.

FIG. 4 shows a partial cross-sectional side view of the air blast valve 20.
Referring to FIG. 4, the housing 21 of the air blast valve 20
A straight needle insertion hole 22 is formed inside,
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 the nozzle port 24 is
The opening / closing is controlled by a valve section 25 formed at the tip of the.
In the embodiment shown in FIG. 4, the nozzle port 24 is arranged in the combustion chamber 4. The needle 23 has a spring retainer.
26 is fixed, and this spring retainer 26 and housing
A compression spring 27 is inserted between the two. The nozzle port 24 is normally closed by the valve portion 25 of the needle 23 by the spring force of the compression spring 27. A movable core 28 is always in contact with the end of the needle 23 opposite to the valve portion 25 by the spring force of a compression spring 29, and a solenoid 30 for sucking the movable core 28 and a stator are provided in the housing 21. 31 is arranged. When the solenoid 30 is energized, the movable core 28 moves toward the stator 31, and as a result, the needle 23 moves in the direction of the nozzle port 24 against the spring force of the compression spring 27, so that the nozzle port 24 is opened. Can be

On the other hand, a cylindrical nozzle chamber 32 is formed in the housing 21. One end 32a of the nozzle chamber 32 is connected to the compressed air inflow passage 3
The other end 32b of the nozzle chamber 32 is communicated with the inside of the needle insertion hole 22 through the compressed air outflow passage 35. An injection port 37 of a fuel injection valve 36 is disposed in the nozzle chamber 32, and the injection port 37 further has one end 32a and the other end 32b
Located between. As shown in FIG. 4, the compressed air outflow passage 35 extends straight. The injection port 37 is disposed on the axis of the compressed air outflow passage 35, and fuel having a small divergence angle is injected from the injection port 37 along the axis of the compressed air outflow passage 35. The compressed air outflow passage 35 extends obliquely with respect to the needle insertion hole 22 toward the nozzle port 24, and is obliquely connected to the needle insertion hole 22 at an angle of 20 to 45 degrees with respect to the needle insertion hole 22. .

FIG. 5 shows an overall configuration diagram of the present embodiment. Referring to FIG. 5, reference numeral 40 denotes an intake manifold, 41 denotes a surge tank, 42 denotes an air cleaner, and 43 denotes an air supply pipe connecting the surge tank 41 and the air cleaner 42. In the middle of the air supply pipe 43, an air flow meter 44, a throttle valve 45, and a mechanical supercharger 46 are provided sequentially from the upstream side. Air cleaner
A conduit 47 is branched from an air supply pipe 43 between the air flow meter 44 and the intake pipe 48a of an air compressor 48.
Will be contacted. On the other hand, the discharge port 48b of the air 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.
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 via the return pipe 50.

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 each top dead center.

Referring again to FIG. 4, the needle insertion hole 22, the nozzle chamber 32
The compressed air outflow passage 35 communicates with the air compressor 48 (see FIG. 5) via the compressed air inflow passage 33.
Accordingly, the inside of the needle insertion hole 22, the nozzle chamber 32 and the compressed air outflow passage 35 are filled with compressed air. Fuel is injected into the compressed air from the injection port 37 along the axis of the compressed air outflow passage 35. As shown in FIG. 4, the compressed air outflow passage 35 is obliquely connected to the needle insertion hole 22, so that most of the injected fuel reaches the needle insertion hole 22 around the needle 23 near the valve portion 25. At this time, part 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 collected in the vicinity of the valve portion 25, as soon as the needle 23 opens the nozzle port 24, both the fuel and the compressed air are ejected from the nozzle port 24 into the combustion chamber 4. When the needle 23 opens the nozzle port 24, the compressed air flows from the compressed air inflow passage 33 into the nozzle chamber 32.
And then through the compressed air outflow passage 35
The fuel adhering to the inner wall surface of the compressed air outflow passage 35 and the inner wall surface of the nozzle chamber 32 to travel toward the 24 is carried away by the compressed air flow, and is ejected from the nozzle port 24. Therefore, as soon as the needle 23 is opened, all of the injected fuel is ejected from the nozzle port 24, and when the ejection of all these injected fuels is completed, only the compressed air is injected from the nozzle port 24. Next, 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 51.
Referring to FIG. 1, the fuel-air injection control device 51 includes an electronic control unit 60 and a control circuit 70.

The electronic control unit 60 is composed of a digital computer, and a ROM (read only memory) 62, a RAM (random access memory) 63, a CPU (microprocessor) 64, and an input port 65 interconnected by a bidirectional bus 61.
And an output port 66.

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

The input port 65 is connected to the air flow meter 44 via the A / D converter 74. The input port is connected to a crank angle sensor 52, an ignition switch 53, and a crank reference position sensor 54. On the other hand, output port 66
Is connected to the base of the transistor 77 and the fuel injection valve 36 via drive circuits 75 and 76. Battery 78 has a resistor 79
And the collector of the transistor 77 via the solenoid 30 of the air plast valve 20. Also, the battery 78
AND via ignition switch 53 and NOT element 80
Connected to one of the input terminals of element 72. The other of the input terminals of the AND element 72 is connected to the output port via the external memory 71. The output terminal of the AND element 72 is connected to the base of the transistor 77 via the drive circuit 73.

The moving body of the present embodiment will be described with reference to FIGS. During engine operation Referring to Figure 6, the fuel injection valve 36 at a predetermined crank angle theta ₁ is made to open, the fuel is made to injection into the compressed air outlet passage 35 and the needle insertion hole 22. At the same time, the flag F is set to 1 and stored in the external memory 71. fuel injection valves 36 is made to closed at theta _2, to end the fuel injection.
Followed by theta _3, the base current flows from the drive circuit 75 to the transistor 77, the transistor 77 is turned on. As a result, the solenoid 30 is energized, and the needle 23 is
Is opened. Therefore, both fuel and compressed air
The fuel is jetted from 24 into the combustion chamber 4. Subsequently, at θ ₄ , the driving circuit 7
The transistor 77 is turned off by 5 and the solenoid 30
Is cut off, and the needle 23 closes the nozzle port 24. At this time, the flag F is reset to 0. The above operation is performed for each rotation of the piston 2. During engine operation, since the ignition switch 53 is always on, the signal inverted by the NOT element 80 and input to the AND element 72 is a 0 level signal, so that the output of the AND element 72 is always at the 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 described with reference to FIG.
Fuel injection valves 36 is made to open the fuel injection is started at the crank angle theta _5. At this time, the flag F is set to 1,
1 is set in the external memory 71. Θ during fuel injection
_{When the} ignition switch 53 is turned off in ₆ ,
The electronic control unit 60 is turned off, and the fuel injection valve 36 is closed. At this time, 1 is maintained in the external memory 71. When the ignition switch 53 is turned off, NOT
The signal input from the element 80 to the AND element 72 is a one-level signal. Therefore, a one-level signal is output from the AND element 72 to drive the drive circuit 73. The drive circuit 73 supplies the discharge current of the capacitor to the base of the transistor 77 for a time determined by the time constant of the discharge circuit, for example, one second.
As a result, the transistor 77 is turned on for one second, and the solenoid 30 is turned on, so that both fuel and air are ejected from the nozzle port 24 into the combustion chamber 4.
The flag F is not reset at this time. When the electronic control unit 60 is turned on next time when the engine is started, the flag F is initialized and reset to zero.

In this embodiment, when the ignition switch 53 is off, a one-level signal is output from the AND element 72 only when 1 is set in the external memory 71, and the needle 2
3 opens the nozzle port 24 and fuel is ejected with air. Therefore, when the flag F is reset to 0, that is, from when the solenoid 30 of the air blast valve 20 is turned off to when the next fuel injection valve 36 is opened (from θ _{4 in} FIG. 6). The nozzle port 24 is not opened even if the ignition switch 53 is turned off during the period up to θ ₁ ′). In this case, the entire fuel is injected from the nozzle port 24 by the compressed air injection action, and no fuel remains in the compressed air outflow passage 35, the needle insertion hole 22, and the like.

As described above, according to the present embodiment, when turning off the ignition switch 53, if the fuel injected from the fuel injection valve 36 remains in the needle insertion hole 22 or the like, the solenoid 30 is energized. The nozzle port 24 is opened, and 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. Therefore, when the engine is started next time, the fuel is measured again, and there is no possibility that the amount of fuel injected from the nozzle port 24 increases and becomes overrich. In addition, since no fuel remains in the needle insertion hole 22 or the like, it does not cause adhesion of carbon and deposits.

FIG. 8 shows a routine for executing fuel-air injection control during engine operation. In this routine, the crank is interrupted at each top dead center.

First, at step 100, Q / N is calculated from the intake air amount Q detected by the air flow meter 44 and the engine speed N detected by the crank angle sensor 52. Q / N corresponds to engine load. In step 101, a basic fuel injection time TP is obtained from a two-dimensional map of Q / N and N, and the basic fuel injection time TP is multiplied by a correction coefficient to calculate a fuel injection time TAU. In step 102,
Fuel injection start crank angle theta ₁ is calculated from the TAU and the fuel injection termination crank angle theta ₂ Metropolitan (see FIG. 9). Here, θ ₂ is a fixed crank angle. In step 103 crank angle theta is determined whether it is theta _1. Crank angle θ
There the fuel injection valve 36 proceeds to step 104 becomes a theta ₁ there is provided brought opening the fuel injection is started. In step 105, the flag F is set to 1. In step 106, it is determined whether or not the crank angle θ has become θ ₂ (see FIG. 9). fuel injection valves 36 proceeds to step 107 when theta is theta ₂
Is closed, and the fuel injection ends. In step 108, it is determined whether or not θ has become θ ₃ (see FIG. 9).
theta is allowed to turn on the solenoid 30 proceeds to step 109 becomes a theta _3. As a result, fuel and air are injected from the nozzle port 24 into the combustion chamber 4. In step 110, it is determined whether or not θ has become ₄ (see FIG. 9). When θ becomes ₄ , the routine proceeds to step 111, where the solenoid 30 is turned off. As a result, the nozzle port 24 is closed by the needle 23. In step 112, the flag F is reset to 0.

FIG. 10 shows a second embodiment. Referring to FIG. 10, the battery 78 is connected via the ignition switch 53 to
One is connected to one input terminal of the AND element 121 via the NOT element 120, and the other is connected to the other input terminal of the AND element 121 via the delay circuit 122. The output terminal of AND element 121 is OR element 12.
3 is connected to one of the input terminals. The other input terminal of the OR element 123 is connected to the electronic control unit 60. OR element 123
Is connected to the solenoid 30 (see FIG. 4) of the air plast valve 20 via the drive circuit 124. Fuel injection valve
36 is connected to the electronic control unit 60. The electronic control unit 60 includes an air flow meter 44 and a crank angle sensor 5.
2. The ignition switch 53 and the crank reference position sensor 54 are connected.

The operation of this embodiment is basically the same as that of the first embodiment, and the operation of this embodiment will be described with reference to FIGS. 6 and 7. At the time of engine operation, the predetermined crank angle θ
₁ fuel injection valve 36 is made to open at, is caused to closed at theta _2. Subsequently, at θ ₃ , a solenoid energizing signal is sent from the electronic control unit 60, and this signal is input to the drive circuit 124 via the OR element 123. As a result, the solenoid 30 (see FIG. 4) is energized, and the needle 23 is
24 is opened. At this time, both the fuel and the compressed air are ejected from the nozzle port 24 into the combustion chamber 4. Then θ
_{In 4} , the solenoid deactivation signal from the electronic control unit 60 is ORed
The signal is sent to the drive circuit 124 via the gate 123. As a result, the solenoid 30 is deenergized, and the needle 23 is
24 is closed. Note that, during engine operation, the ignition switch 53 is always on, so the signal inverted by the NOT element 120 and input to the AND element 121 is a 0 level signal, so that the output of the AND element is always a 0 level signal. It is. Therefore, during engine operation, the solenoid 30 is not energized depending on the output signal of the AND element 121.

During engine stops, the fuel injection valve 3 at a crank angle theta ₅
6 is opened. When the ignition switch 53 is turned off in the theta ₆ during the fuel injection period, the electronic control unit 60 is turned off, the fuel injection valve 36 is made to closed.
When the ignition switch 53 is turned off, the NOT element 120
Becomes 1 from the input to the AND element 121. On the other hand, the signal input to the AND element 121 via the delay circuit 122 is
1 is maintained only during the delay time of the delay circuit. Therefore, AN
One signal is output from the D element 121 and input to the drive circuit 124 via the OR element 123. As a result, the drive circuit 124
When the solenoid 30 is energized, the needle 23 opens 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 residual fuel is ejected from the nozzle port 24 into the combustion chamber 4 together with the compressed air.

In the present embodiment, regardless of whether the fuel injected from the fuel injection valve 36 remains in the needle insertion hole 22 or the like,
The solenoid 30 is energized to open the nozzle port 24, and compressed air is ejected from the nozzle port 24. That is, in this embodiment, regardless of the timing at which the ignition switch 53 is turned off, when the ignition switch is turned off, the compressed air is always ejected from the nozzle port 24 only during the delay time of the delay circuit 122.

Therefore, in the present embodiment, the same effects as in the first embodiment can be obtained without using the flag F of the first embodiment.

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

〔The invention's effect〕

As described above, according to the present invention, when the engine is stopped,
Since the fuel supplied into the compressed air passage is always injected from the nozzle port by the compressed air, the fuel does not remain in the compressed air passage. Therefore, when the engine is started next time, the accuracy of the fuel amount injected from the nozzle port does not decrease.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a fuel air injection control device according to a first embodiment of the present invention, FIG. 2 is a bottom view of an inner wall surface of a cylinder head, and FIG.
FIG. 4 is a side cross-sectional view of a two-stroke engine, FIG. 4 is a partial cross-sectional side view of an air plast valve, FIG. 5 is an overall configuration diagram of the first embodiment, and FIGS. 6 is an operation explanatory diagram, FIG. 6 is a diagram showing engine operation, FIG. 7 is a diagram showing engine stop, FIG. 8 is a flowchart for executing fuel air injection control, FIG. 9 is a diagram showing a fuel injection engine, etc. FIG. 10 is a main configuration diagram of the second embodiment. 20 ... air plast valve, 22 ... needle insertion hole, 23 ... needle, 24 ... nozzle port, 30 ... solenoid, 32 ... nozzle chamber, 35
... 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)

(57) [Claims] 1. After supplying fuel into a compressed air passage having a nozzle port formed at a tip thereof, compressed air supplied into the compressed air passage is injected from the nozzle port together with the fuel from the nozzle port. In a fuel injection device in which fuel supply and compressed air injection are alternately and repeatedly performed to perform fuel air injection control, an internal combustion engine that completes the fuel air injection control by compressed air injection when an engine is stopped. Engine fuel injector.