JPH068286Y2 - Fuel injection device for two-cycle internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a fuel injection device for a two-cycle internal combustion engine equipped with an intake / exhaust valve.

[Conventional technology]

In a two-cycle internal combustion engine, a fuel injection type engine provided with an intake valve and an exhaust valve in order to obtain a high output has been proposed. (For example, see Japanese Patent Application No. 62-62727.) In this case,
The fuel injection valve is installed in the intake port, and the timing of fuel injection is set at a so-called overlap when both the intake valve and the exhaust valve are open. That is, by injecting fuel into the intake port, the piston can be carried on the intake flow during the intake stroke toward the bottom dead center to supply the fuel to the combustion chamber in a good mixed state. In this case, the timing of fuel injection sets the timing of fuel injection when both the intake valve and the exhaust valve, which are substantially before the bottom dead center of the piston, are open.

[Problems to be solved by the device]

In the prior art, the fuel injection is executed at the timing when both the intake valve and the exhaust valve are opened, so that some of the fuel introduced into the combustion chamber through the intake port does not remain in the combustion chamber. There is a risk of blowing through the exhaust port. Therefore, there is a problem that the fuel consumption rate deteriorates.

It is an object of the present invention to provide a fuel injection device capable of maintaining a good mixed state with air without fear of fuel blowing through.

[Means for Solving the Problems]

In order to achieve the above object, the present invention includes an intake valve and an exhaust valve as shown in FIG. 1A, and closes the intake valve and the exhaust valve so that the intake valve is closed after the exhaust valve is closed. In a two-cycle internal combustion engine with set timing, fuel supply means for directly supplying fuel into the combustion chamber, rotational speed detection means for detecting the rotational speed of the engine, and closing of the air supply valve when the engine is running at low speed. After starting the valve, the fuel supply to the combustion chamber is started, and at the time of high engine speed, the fuel supply to the combustion chamber is started after the exhaust valve is closed and before the air supply valve is closed. As described above, the fuel injection device for a two-cycle internal combustion engine is provided with the control means for operating the fuel supply means.

[Action]

FIG. 1B is a crank angle diagram for explaining the operation of the present invention. In the figure, EXO is the opening timing of the exhaust valve, INO is the opening timing of the intake valve, EXC is the closing timing of the exhaust valve, INC is the closing timing of the intake valve, EX is the opening period of the exhaust valve, IN Indicates the opening period of the air supply valve.

As shown in FIG. 1B, in the present invention, the intake valve is closed (INC) after the exhaust valve is closed (EXC). A indicates the range of the fuel supply start timing at the time of low engine speed, and the fuel is injected after closing the air supply valve. B indicates the range of the fuel supply start timing at the time of high engine rotation, and the fuel injection is started after the exhaust valve is closed and before the air supply valve is closed.

Therefore, at low engine speed, the fuel is supplied after the intake valve is closed, that is, both the intake valve and the exhaust valve are closed, and the gas flow in the combustion chamber is stabilized, so that the combustion chamber The dispersion of the fuel supplied to is suppressed and a rich air-fuel mixture layer is formed.

At high engine speed, when the fuel supply is started, the air supply valve is open, so a flow of fresh air is formed in the combustion chamber, and this new air flow causes the supplied fuel to enter the combustion chamber. Spread. Further, at the time of low engine speed and high engine speed, fuel is supplied after the exhaust valve is closed, so that fuel does not blow through the exhaust gas passage.

〔Example〕

In FIGS. 2 and 3, 10 is a cylinder head of a two-cycle internal combustion engine, 11 is a combustion chamber, 12 is a cylinder block,
13 is a piston and 14 is a spark plug. This two-cycle internal combustion engine is provided with an intake valve 15 and an exhaust valve 16, and is of a four-valve type having two intake valves 15 and two exhaust valves 16. 18 is each air supply valve 1
4 is an intake port, and air pressurized by a supercharger (not shown) provided upstream is supplied. Reference numeral 20 denotes an exhaust port from each exhaust valve 16.

The air supply valve 15 and the exhaust valve 16 are, as shown in FIG. 1B,
As the crank angle progresses from top dead center (TDC) to bottom dead center (BDC), the exhaust valve first opens at EXO and then IN
The air supply valve opens at O. Further, after passing through the bottom dead center (BDC), the exhaust valve is closed at EXC, and then the air supply valve is closed at INC, which is operated by a valve operating system mechanism (not shown).

The fuel injector is shown generally at 22 and its body 24
Are fastened and fixed to the cylinder head 10 by bolts 25. FIG. 4 shows a detailed configuration of the fuel injection device 22. The fuel injection device 22 is inserted and installed in the partition wall 10A of the cylinder head 10 that separates the two intake ports 18. In FIG. 4, the fuel injection device 22 has a body 24, a holder 26 is provided at the tip of the body 24, and an automatic valve 28 is arranged at the tip. Automatic valve 28 is spring 3
In the normal state, the valve is closed by 0, and when compressed air pressure is applied, the valve opens outward, the jet port 31 opens, and the valve opens. The fuel control valve 32 has a fuel injection port 34 at one end, and this injection port 34 is normally closed by a needle 36, but the needle 36 is lifted by operating an electromagnetic drive mechanism (not shown), and the fuel is discharged from the injection port 34. Erupted. The injection port 34 has a hole shape. This fuel is
It is temporarily accumulated in a fuel passage 38 connecting the injection port 34 and the automatic valve 28. Reference numeral 40 is a delivery pipe for fuel and air.

2 and 3, the injection port 3 of the fuel injection device 22 is shown.
1 is directly open to the combustion chamber 11, and the spray F from the injection port 31 is arranged so that the center line thereof coincides with the center line of the cylinder bore, and the spray direction is a vertical plane in which the crown 13A of the piston 13 is located. A downward angle of θ is aimed at, and the angle is such that the upper edge does not contact the spark plug electrode 14A, and the lower edge is close to the inner surface of the cylinder bore.
That is, it is set so that fuel does not adhere to the inner surface of the cylinder bore.

In FIG. 4, the control circuit 52 is configured as, for example, a microcomputer system, and has a functional configuration that controls the operation of the air injection valve 46 and the fuel control valve 32 to realize desired fuel injection control. The control circuit 52 includes a crank angle sensor 54, a rotation speed sensor 56, a load sensor 58,
The engine cooling water temperature sensor 60, the intake air temperature sensor 62, the intake air amount sensor 63, and other sensors are connected and input to the control circuit 52 as an engine operating condition signal.

Fuel from a fuel tank (not shown) is introduced into the fuel control valve 32 from a fuel pump (not shown) and a fuel passage 42 of the delivery pipe 40 via a fuel filter and a pressure regulator. On the other hand, pressurized air from a compressor (not shown) is introduced into the air injection valve 46 through the air passage 44 of the delivery pipe. A predetermined timing of the internal combustion engine is detected by the crank angle, and a signal is sent from the control circuit 52 to the fuel control valve 32.
, The needle 36 of the control valve 32 is lifted, and fuel is ejected from the injection port 34 into the fuel passage 38. However, the fuel pressure at this time cannot overcome the set pressure of the spring 30 that biases the automatic valve 28 to close, and the automatic valve 28 maintains the closed state. Since the central axis of the injection port 34, the linear fuel passage 38, and the automatic valve 28 are configured in common, the injected fuel is concentrated near the automatic valve. The opening time of the fuel control valve 32 is calculated according to the operating conditions so that the required amount of fuel is metered and accumulated in the passage 38.

At the fuel injection timing, the air injection valve 46 is opened, and the pressurized air is injected from the injection port 48 through the passage 50 to the fuel passage 38 from the upstream side of the injection port 34 of the fuel control valve 32. Since this air pressure is higher than the set pressure of the spring 30 of the automatic valve 28, the fuel in the passage 38 together with the air opens the automatic valve 28 and is injected into the combustion chamber 11. At this time, the fuel is finely crushed by the air flow, and good combustion can be achieved. The pressurized air is introduced from the upstream side of the injection port 34 through the injection port 48 in order to blow out the injected fuel that adheres to the wall surface of the passage immediately after the injection port 34, as in the embodiment. In the case of a single type fuel injection port, it is not always necessary to introduce from the upstream side.

Next, the fuel injection timing into the combustion chamber 11 in the above-mentioned fuel injection device will be described. FIG. 5 is a crank angle diagram for explaining each operation period in the fuel injection process, in which: τ _f The valve opening time of the fuel control valve 32, that is, the measured amount of fuel T _d ; the delay time from the end of metering to the start of air injection τ _a ; the opening time of the air injection valve 46 i. T. The respective periods from TDC that set the air injection end timing are shown.

The fuel injection timing into the combustion chamber 11 is τ _f ,
T _d , τ _a , and i. T. It can be controlled by changing the start time or end time of each period.

FIG. 10 is a flowchart showing an example of control of fuel injection timing when the valve opening time τ _a of the air injection valve 46 is always constant. This routine is interrupted for each predetermined crank angle.

In step 101, the intake air amount Q, the engine rotation speed N and the cooling water temperature TH _w are read. Then proceed to step 102, where the water temperature
It is determined whether TH _w is 60 ° C. or higher, and if YES, the process proceeds to step 103, and the coefficient f is set to 1.0. Also, step 10
If NO is determined in 2, the process proceeds to step 104 and the coefficient f
To 1.2. In step 105, the fuel supply amount TAU is obtained from the intake air amount Q, the rotation speed N, and the coefficient f, and the valve opening time τ _f of the fuel control valve 32 is obtained from TAU. In step 102, when the cooling water temperature TH _w is 60 ° C. or lower, the coefficient f is set to 1.2 and the fuel supply amount TAU is increased to increase the amount of fuel supplied to the combustion chamber during warm-up operation.

Next, at step 106, the period i.d. from the top dead center (TDC) corresponding to the rotation speed N is determined from the map shown in FIG. T. Ask for. Since the valve opening engine τ _a of the air injection valve 46 is always constant, the start timing of air injection, that is, the fuel injection start timing into the combustion chamber 11 is, as shown in FIG. 11, a top dead center (TDC). From the time to the closing timing of the air supply valve 15
₁ from (FIG. 5 reference), the value T = T ₁ -τ ₂ period i than minus opening period tau _a air injection valve 46. T. When is smaller, it is after the air supply valve 15 is closed. Also, T <
i. T. At the time of, before the intake valve 15 is closed, the combustion chamber 1
The injection of fuel into 1 is started. That is,
When the rotation speed N is N <N _a , the air supply valve 15 is closed, and when N <N _a , the combustion chamber 1 is closed before the air supply valve 15 is closed.
The injection of fuel into 1 is started.

Then in step 107, the period i. T. From this, the end timing θ ₄ of air injection is obtained. In step 108, from the air injection end timing θ ₄ and the valve opening time τ _a of the air injection valve 46, the air injection start timing, that is, the fuel injection start timing θ into the combustion chamber 11.
Ask for ₃ .

Next, at step 109, it is judged if the air injection start timing, that is, the fuel injection start timing θ ₃ into the combustion chamber 11 is earlier than the valve closing timing EXC of the exhaust valve 16. When it is determined that θ ₃ is after EXC, the routine proceeds to step 110, and when it is determined that θ ₃ is before EXC, at step 111, θ ₃ is fixed at EXC and the air injection end timing θ ₄ is obtained from EXC and the air injection period τ _a, and the routine proceeds to step 110.

In steps 109 and 111, the fuel injection start timing θ ₃ is prevented from being before the exhaust valve 16 is closed.

At step 110, the valve opening end timing θ ₂ of the fuel control valve 32 is obtained from the fuel injection start timing θ ₃ and the delay time T _d , and at step 112, from θ ₂ and the fuel control valve 32 opening time τ _f ,
The valve opening start timing θ ₁ of the fuel control valve 32 is calculated, and this routine ends.

FIG. 12 shows a drive routine of the fuel injection device 22.
This routine is a crank angle interrupt routine, and is interrupted every 90 ° CA after the top dead center (TDC), for example.

First, at step 201, it is judged if the crank angle θ of the engine has reached the valve opening start timing θ ₁ of the fuel control valve 32,
When θ = θ ₁ , the routine proceeds to step 202, where the fuel control valve is opened. In step 203, it is determined whether or not θ has reached the opening end timing θ ₂ of the fuel control valve 32. When θ = θ ₂ , the process proceeds to step 204 and the fuel control valve 32 is closed.

In step 205, it is determined whether or not the crank angle θ reaches the valve opening start timing of the air injection valve 46, that is, the fuel injection start timing θ ₃ into the combustion chamber 11, and when θ = θ ₃ , the routine proceeds to step 206. Then, the air injection valve 46 is opened to inject fuel. Next, at step 207, θ is the air injection valve 4
It is judged whether or not the valve opening end timing θ ₄ of 6 has come, and θ =
When the theta _4, the process proceeds to step 208, closes the air injection valve 46, the routine is terminated.

Therefore, the opening / closing control of the fuel control valve 32 and the air injection valve 46 is performed based on θ ₁ , θ ₂ , θ ₃ , θ ₄ obtained in the flowchart of FIG. 10, and the air injection valve 46 starts to open. _{At 3} , the combustion injection into the fuel chamber 11 is started.

The fuel injection start timing θ ₃ is when the engine speed N is N _a (11th
As shown in the drawing), when the engine speed is on the low rotation side, it is closer to the top dead center (TDC) than the valve closing timing INC of the air supply valve 15. Therefore, since the fuel is injected into the combustion chamber 11 after both the intake valve 15 and the exhaust valve 16 are closed, the injected fuel is not dispersed by the new air flow or the exhaust flow, and Concentrated near the crown portion 13A, as the piston 13 rises, a rich mixture layer is formed near the spark plug electrode 14A. Therefore, reliable ignition and combustion can be obtained even if the amount of residual gas is large.

On the other hand, when the engine speed N becomes higher than N _a (FIG. 11), the fuel injection start timing θ ₃ is at the bottom right (BDC) side of the valve closing timing INC of the air supply valve 15. Therefore, since the fuel is injected when the air supply valve 15 is open,
Due to the flow of fresh air flowing into the combustion chamber 11, this injected fuel is dispersed throughout the combustion chamber. In addition, since the fuel injection timing shifts to the bottom dead center (BDC) side, the retention time of the fuel in the combustion chamber until ignition becomes long, and the injected fuel is well dispersed. Therefore, at high speed,
A homogeneous air-fuel mixture is formed in the entire combustion chamber 11, enabling stable combustion.

Further, since the fuel injection start timing θ ₃ does not shift to the bottom dead center (BDC) side of the valve closing timing EXC of the exhaust valve 16 (see steps 109 and 111 in FIG. 11), the injected fuel does not blow through. Absent.

Further, in this embodiment, since the fuel injection device 22 for injecting fuel with air pressure is used as the fuel supply means into the combustion chamber 11, the time from fuel injection to ignition is particularly short at low rotation speed. However, the atomization of the fuel is good and reliable ignition is possible. Also, the injected fuel will not adhere to the side wall as it is.

In this embodiment, as shown in FIG. 11, the period i. T. The fuel injection start timing θ ₃ is controlled by increasing the rotational speed N as the rotational speed N increases. T. You may change things other than.

For example, as shown in FIG. T. Delay time T
_The valve opening time τ _a of the air injection valve may be increased as the rotational speed is increased, with _d always kept constant. In this embodiment, when the rotation speed is higher than N _b , fuel injection is performed before the intake valve 15 is closed.

Further, as shown in FIG. 7, the period i. T.
Is changed according to not only the rotation speed but also the engine load, so that at low rotation and low load, after the air supply valve 15 is closed, at high rotation and high load, before the fuel injection valve 15 is closed, The injection may be started.

In order to improve the spray of the fuel injection device 22, the injection start timing and the delay time T _d depend on the cooling water temperature, the intake air temperature, etc.
It is also possible to change etc. For example, FIG. 8 shows an example of settings for water temperature. When the water temperature is high, the injection is delayed by increasing T _d . That is, the time during which the fuel stays at the tip of the injection valve becomes longer, and atomization can be promoted. On the other hand, when the water temperature is low, i. T. Is increased, fuel injection is accelerated, the time during which the fuel is present in the combustion chamber 11 is increased, and atomization can be promoted.

FIG. 9 shows the setting for the intake air temperature, and the aim is the same as the case of the water temperature.

[Effect of device]

According to this invention, fuel is supplied into the combustion chamber after closing both the intake valve and the exhaust valve at low speed, and at high speed before the closing of the intake valve and after closing the exhaust valve. Since the fuel is supplied to the fuel tank, it is possible to prevent the fuel from blowing through, form a rich air-fuel mixture layer without dispersing the fuel at low speed, and disperse the fuel at high speed to evenly distribute the fuel in the combustion chamber. A mixture can be formed. Therefore, stable combustion can be realized over each rotation speed.

[Brief description of drawings]

FIG. 1A is a diagram showing the configuration of this invention. FIG. 1B is a crank angle diagram for explaining the fuel injection timing in this invention. FIG. 2 is a transverse sectional view of an internal combustion engine equipped with the fuel injection device of the present invention. FIG. 3 is a vertical sectional view of an internal combustion engine equipped with the fuel injection device of the present invention. FIG. 4 is a detailed sectional view of the fuel injection device. FIG. 5 is a crank angle diagram for explaining each timing of operation of the fuel injection device in the embodiment of the present invention. 6 to 9 and 11 are diagrams for explaining each mode of operation timing of the fuel injection device of the present invention. FIG. 10 is a flowchart showing an example of control of fuel injection timing. FIG. 12 is a drive routine of the fuel injection device. 11 ... Combustion chamber, 13 ... Piston, 14 ... Spark plug electrode, 15 ... Air supply valve, 16 ... Exhaust valve, 22 ... Fuel injection device, 31 ... Injection port, 32 ... Fuel control valve, 46 ... Air injection valve.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display area F02D 41/34 F 8011-3G (72) Creator Tateno Mana 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Auto Car Co., Ltd. (56) References Special Table Sho 63-500322 (JP, A)

Claims (1)

[Scope of utility model registration request] 1. A two-cycle internal combustion engine having an intake valve and an exhaust valve, wherein the intake and exhaust valve closing timings are set so that the intake valve is closed after the exhaust valve is closed. A fuel supply means for supplying fuel to the engine, a rotation speed detection means for detecting a rotation speed of the engine, and at the time of low engine speed, start fuel supply to the combustion chamber after closing the air supply valve and At high rotation speed, after the exhaust valve is closed and before the air supply valve is closed, a control means for operating the fuel supply means so as to start fuel supply into the combustion chamber, A fuel injection device for a two-cycle internal combustion engine, each of which is provided.