JPH04132857A - Fuel feeding device for engine - Google Patents

Abstract

PURPOSE:To improve an output by disposing an injector on the combustion chamber side and an injector on the suction passage side and increasing the injection ratio of the injector on the suction passage with the increase in rotation and a load. CONSTITUTION:An injector 13 on the combustion chamber side to inject fuel directly in a combustion chamber 3 and an injector 14 on the suction passage side to inject fuel to a suction passage 10 are disposed. Injection of fuel through the injectors 13 and 14 is controlled so that the injection ratio of the injector 14 on the suction passage side is increased with the increase in rotation and a load. Namely, by injecting fuel in a high ratio through the injector 13 on the combustion chamber side during low rotation low load running, stratified combustion is carried out. During high rotation high load running, atomization of fuel and mixture of fuel with air are promoted by the increase of the injection ratio of the injector 14 on the suction passage side. This constitution increases air utilization efficiency and improves an output.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel supply system for an upward flow uniflow two-stroke engine.

[Conventional technology]

Conventionally, for example, as shown in Japanese Patent Application Laid-Open No. 59-49316, a scavenging port that is opened and closed by the vertical movement of a piston is provided below the combustion chamber of a cylinder, and an exhaust valve is provided above the combustion chamber. Upflow uniflow two-stroke engines are generally known that are provided with an exhaust port that is controlled by the engine. In this engine, intake air pressurized by a supercharger is sent into the combustion chamber through the scavenging port, and waste gas is forced out through the upper exhaust port.

Although the engine shown in the above publication is a two-stroke diesel engine, upward flow uniflow type two-stroke gasoline engines are also known, and in the case of a gasoline engine, the scavenging port, exhaust port, and supercharger are In addition to the above, it is also equipped with spark plugs, injectors, throttle valves, etc.

[Problem to be solved by the invention]

By the way, in conventional upward flow uniflow two-stroke engines, fuel is supplied from a fixed position. For example, an injector is installed at the top of the combustion chamber, and fuel is injected directly into the combustion chamber from this injector. Ru. According to this device, stratified combustion occurs in which the fuel injected from the injector is unevenly distributed near the spark plug, resulting in fuel savings and improved combustibility at low loads. However, by simply injecting fuel directly into the combustion chamber, the air utilization rate is insufficient at high loads, and fuel atomization and mixing with air become poor at high engine speeds, where the time for one engine cycle is shortened. Problems remain.

In view of the above circumstances, the present invention provides an upward flow uniflow type two-stroke engine that improves fuel efficiency and combustibility at low engine speeds and low loads, while promoting fuel atomization and air-fuel mixture at high engine speeds and high loads. It is an object of the present invention to provide a fuel supply device that can equalize the air utilization rate, increase the air utilization rate, and improve the output.

[Means to solve the problem]

In order to achieve the above-mentioned objects, the present invention provides an upward flow uniflow two-stroke engine having a scavenging port below the combustion chamber and an exhaust port above the combustion chamber. An intake passage side injector for injecting fuel is arranged in the intake passage leading to the scavenging port, and fuel is injected from each of the above injectors so as to increase the injection ratio of the intake passage side injector as the rotation becomes high or the load becomes high. A fuel injection control means for controlling injection is provided.

In this configuration, the scavenging port is capable of introducing intake air in two directions: a direction relatively upward into the combustion chamber and a direction downward from this, and scavenging adjustment is performed to adjust the intake air introduction ratio in these two directions. It is preferable to provide scavenging means for controlling the scavenging adjusting means so as to increase the intake air introduction ratio in the downward direction as the injection ratio from the intake passage side injector increases.

[Effect]

According to the above configuration, when the engine speed is low and the load is low, stratified combustion is performed by injecting a large proportion of fuel from the combustion chamber side injector, and when the engine speed is high or the load is high, the injection rate from the intake passage side injector is reduced. By increasing the size, atomization of the fuel and mixing with air can be promoted.

Furthermore, if the configuration is configured such that the intake air introduction ratio in the downward direction of the scavenging port increases as the injection ratio from the intake passage side injector increases, when the injection ratio from the intake passage side injector increases, the injection rate from this injector increases. A sufficient amount of fuel is also sent to the lower part of the combustion chamber, resulting in the effect of increasing the homogenization of the air-fuel mixture.

〔Example〕

Embodiments of the present invention will be described based on the drawings.

FIG. 1 schematically shows the overall structure of an apparatus according to an embodiment of the present invention, and FIG. 2 shows the specific structure of this apparatus. In these figures, a piston 2 is fitted into a cylinder 1 of a two-stroke engine, and a combustion chamber 3 is formed above the piston 2. A scavenging port 4 is provided below the combustion chamber 3 and is opened and closed by the vertical movement of the piston 2. On the other hand, an exhaust port 7 is provided in the cylinder head 5 located above the combustion chamber 3 and is opened and closed by an exhaust valve 6. is provided. The exhaust valve 6 is opened and closed by a valve mechanism such as a camshaft 8.

A supercharger 11 is provided in the intake passage 10 leading to the scavenging port 4.
is provided, and this supercharging t! The intake air pressurized by the valve 111 is sent to the scavenging port 4 via the check valve 12. Then, when the piston 2 is in the downward position after undergoing explosive expansion, the exhaust valve 6 is opened and the intake air from the supercharger 11 is sent from the scavenging port 4 to the combustion chamber 3.
By sending air into the interior, upward uniflow scavenging is performed, and after the exhaust valve 6 is closed, the scavenging port 4 is
is closed by the piston 2.

As a fuel supply system for this engine, a combustion chamber side injector 13 that injects fuel directly into the combustion chamber is provided in the cylinder head 5, and an intake passage side injector 14 that injects fuel into the intake passage 10 is installed in the scavenging port 4. It is provided in the intake passage 10 near the. Further, the cylinder head 5 is provided with an ignition plug 15, and the ignition plug 15 is connected to the combustion chamber side injector 13.
The structure is such that fuel is injected near 5.

Furthermore, in this embodiment, the scavenging port 4 is composed of two types of ports 4a and 4b, an upper side and a lower side.
Intake air can be drawn in two directions: relatively upward in the combustion chamber and downward. That is, the lower scavenging port 4b is provided at a position near the lowest part of the combustion chamber 3 when the piston 2 is descending, and the upper scavenging port 4a is provided above the lower scavenging port 4b. , these ports 4a, 4b are each arranged at a plurality of locations in the circumferential direction of the cylinder wall.

The intake passage 10 branches near its downstream end into a passage 10a communicating with the upper scavenging port 4a and a passage 10b communicating with the lower scavenging port 4b. And, as a scavenging air adjustment means for adjusting the intake air introduction ratio in the above two types of directions,
A scavenging adjustment valve 16 for opening and closing the passage 10b is provided in a passage 10b communicating with the lower scavenging port 4b. The intake passage 10 is also provided with an air 70-meter for detecting the amount of intake air, a throttle valve (not shown) that operates in response to accelerator operation, and the like.

As shown in FIG. 1, each of the injectors 13 and 14 and the scavenging air adjustment valve 16 are controlled by a control unit (ECU) 20 comprising a microcomputer or the like. The control unit 20 receives signals from a crank angle sensor 25 that provides a crank angle signal for detecting engine speed, etc., and a throttle opening sensor 26 that detects the opening of a throttle valve. An intake air amount detection signal from the air 70 meter is also input.

The control unit 20 includes a fuel injection control means 21 and a scavenging control means 22. The fuel injection control means 21 increases the injection ratio of the intake passage side injector 14 as the rotation becomes high or the load becomes high. For example, at low rotation and low load, fuel is injected only from the combustion chamber side injector 13; Controls fuel injection from each of the injectors 13 and 14 in accordance with detection signals of engine rotation speed and throttle opening so that fuel is also injected from the intake passage side injector 14 at a certain rate when the rotation is high or the load is high. do. Further, the scavenging control means 22 is configured to open the scavenging adjustment valve 16 to increase the proportion of intake air introduced into the lower scavenging port 4b as the injection proportion from the intake passage side injector 14 increases. The scavenging adjustment valve 16 is controlled via the actuator 17.

1lIIWJ as the fuel injection control means 21 and scavenging control means 22 by this control unit 20.
A specific example will be explained with reference to the flowcharts of FIGS. 3 to 5.

FIG. 3 shows the main routine. In this routine, first, in step S1, the crank angle signal, throttle opening θ, and intake air IQa are read, in step S2, the engine rotation speed Ne is calculated based on the cycle measurement of the crank angle signal, and in step S3, the engine rotation speed Ne is Basic injection pulse width Tp corresponding to the intake air ff1 (Qa/Ne)
Calculate. Next, in step S4, the engine speed Ne
Determine whether or not is in the low rotation range lower than the set rotation speed No.
If the determination is YES, it is checked in step S5 whether or not the throttle opening θ is in a low load range smaller than the set opening θ0.

When the determinations in steps 84 and 85 are both YES at low rotation and low load, in step S8, the injection pulse width Td of the combustion chamber side injector 13 is adjusted by multiplying the basic injection pulse width Tp by 1 by a predetermined correction coefficient. In addition, the injection pulse width Tm of the intake passage side injector 14
Let be 0.

Furthermore, in step S7, the scavenging adjustment valve 16 is controlled to be in a closed state.

Also, when the determination in step 34.85 is NO, that is, when the rotation is high above the set rotation speed N0 or when the load is high above the set throttle opening θO,
In step S8, the injection ratio (a:b) is set so that injection is performed from both injectors 13 and 14,
The injection pulse width Td of the combustion chamber side injector 13 is determined by multiplying the basic injection pulse width Tp by [a/ (a+b)] and the correction coefficient by 2, and
The injection pulse width Tp is [b/ (a+b)] and the correction coefficient is 3.
The injection pulse width Tm of the intake passage side injector 14 is determined by multiplying by . In this process, the ratio (a:b) may be set constant, but it is preferable to set it according to the engine speed and engine load. , the ratio of injection from the intake passage side injector 14 [b/ (a+
b)] may be set to increase as the engine speed increases and the intake air IQa increases. Following the processing in step S8, in step S9, the scavenging adjustment valve 16 is controlled to be in an open state. When the ratio (a:b) is set according to the operating condition, as the value of [b/(a+b)] increases, as shown in FIG. You can set it to be larger.

FIG. 4 shows an interrupt routine for executing injection from the combustion chamber side injector 13. In this routine, it is checked based on the crank angle signal, etc. whether or not the preset combustion chamber side injector injection timing has arrived (step 511).
When the injection timing comes, injection from the combustion chamber side injector 13 is executed by outputting an injection pulse having the pulse width Td determined in the main routine.

FIG. 7 shows an interrupt routine for executing injection from the intake passage injector 14. This routine also checks whether the preset intake passage side injector injection timing has arrived based on the crank angle signal, etc. (step 521).
), when the injection timing comes, the injection from the intake passage side injector 14 is executed by outputting an injection pulse with the pulse width Tm determined in the main routine. In this case, in step S6 of the main routine, the pulse width Tm
is set to O, the intake passage side injector 14
There is no injection from.

According to the device of this embodiment, fuel is injected only from the combustion chamber side injector 13 when the engine is at low rotation speed and low load. That is, at a predetermined time after scavenging is performed and the exhaust valve 6 is closed, fuel is directly injected into the combustion chamber 3 from the combustion chamber side injector 13, and this fuel is unevenly distributed near the spark plug 15 and stratified. By performing combustion, fuel efficiency and combustibility are improved at low rotation speeds and low loads. Furthermore, during low rotation and low load, the scavenging adjustment valve 16 is closed, and the intake air is sent relatively upwardly into the combustion chamber 3 from the upper scavenging port 4a during scavenging. Scavenging of waste gas, which is present in large quantities in the air, is carried out efficiently.

On the other hand, during high rotation or high load, the injection ratio from the combustion chamber side injector 13 is reduced and fuel injection is also performed from the intake passage side injector 14.

The fuel injected from the intake passage injector 14 flows into the combustion chamber 3 via the scavenging port 4, and during this time, atomization and mixing with air are promoted, even at high engine speeds where one cycle time is short. The fuel is sufficiently atomized, and the air utilization rate is increased, resulting in increased output under high loads. Furthermore, at this high speed or high load, the scavenging adjustment valve 16 is opened and the intake air is sent into the combustion chamber 3 from the lower scavenging port 4b, so that the fuel injected from the intake passage injector 14 is combusted. It is also sufficiently supplied to the lower part of the combustion chamber 3, and the effect of making the air-fuel mixture in the combustion chamber 3 uniform is enhanced.

In particular, the injection ratio from the intake passage side injector 14 and the intake air introduction ratio from the lower scavenging port 4b,
By increasing the amount continuously or in multiple stages as the engine speed and load increase, the above-mentioned effect can be effectively exerted depending on the operating condition.

In the present invention, the scavenging port 4 has a structure that allows intake air to be introduced in two directions, upward and downward, as in the above embodiment, the upper scavenging port 4a and the lower scavenging port 4b.
The present invention is not limited to a structure in which a direction-variable intake guide member is provided in the scavenging port, and a mechanism for operating the intake guide member may be provided as a scavenging adjustment means.

〔Effect of the invention〕

As described above, the present invention provides an upward flow uniflow two-stroke engine in which a combustion chamber side injector and an intake passage side injector are arranged, and the injection ratio of the intake passage side injector is adjusted as the rotation becomes high or the load becomes high. Because of its large size, this type of uniflow 2-stroke engine improves fuel efficiency through stratified combustion at low speeds and low loads, while also promoting atomization of fuel and mixing with air at high speeds and high loads. It is possible to increase the utilization rate and improve the output.

Furthermore, the scavenging port is configured to allow intake air to be introduced in two directions, upward and downward, and the scavenging air adjustment means and scavenging control means are used to introduce intake air in the downward direction as the injection ratio from the intake passage side injector increases. According to the configuration in which the proportion is increased, when stratified charge combustion is performed, effective scavenging is performed in accordance with the stratified combustion, while at the same time, the injection rate from the intake passage side injector increases at high rotation speeds or under high load. In some cases, it is possible to promote mixing with air and improve the effect of making the air-fuel mixture uniform, thereby further improving output.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of the overall configuration of the @ location according to an embodiment of the present invention, FIG. 2 is a sectional view showing the specific structure, FIGS. 3 to 5 are control flowcharts, and FIGS. FIG. 7 is a characteristic diagram of the controlled mt amount. 1... Cylinder, 3... Combustion chamber, 4... Scavenging port, 6... Exhaust valve, 7... Exhaust port, 10...
Intake passage, 13... Combustion chamber side injector, 14...
- Intake passage side injector, 16... scavenging air adjustment valve, 20... control unit, 21... fuel injection control means, 22... scavenging air control means. Figure 1 Patent applicant Mazda Corporation representative
People Patent Attorney Etsushi Kotani
Patent Attorney Chief 1) Masamukai Patent Attorney
9 Takao Fuji

Claims (1)

[Claims] 1. In an upward flow uniflow two-stroke engine having a scavenging port below the combustion chamber and an exhaust port above the combustion chamber, a combustion chamber-side injector that directly injects fuel into the combustion chamber communicates with the scavenging port. An intake passage side injector that injects fuel into the intake passage is arranged, and fuel injection from each of the above-mentioned injectors is controlled so as to increase the injection ratio of the intake passage side injector as the rotation becomes high or the load becomes high. A fuel supply device for an engine, characterized in that it is provided with an injection control means. 2. The scavenging port is capable of introducing intake air in two directions, a direction relatively upward into the combustion chamber and a direction downward from this, and a scavenging adjustment means for adjusting the intake air introduction ratio in these two directions. Claim 1, further comprising scavenging control means for controlling the scavenging air adjusting means so as to increase the intake air introduction ratio in the downward direction as the injection ratio from the intake passage side injector increases. Fuel supply system for the engine described.