JPH0633803A - Fuel supply device of engine - Google Patents

Abstract

PURPOSE:To utilize exhaust gas as a gas for composing mixture to an air- mixture supply port, and obviate any device for pressurizing while performing atomization of fuel properly, and to enhance the effect of improvement of fuel consumption and also improve emission. CONSTITUTION:The exhaust valve opening timing of a first exhaust port 5 becomes sooner than an exhaust valve opening timing of a second exhaust port 6, and an exhaust shutter valve 25 is provided on the way of the first exhaust port 5, and its upstream part and a mixture supply port 7 are communicated with each other by a communication passage 27, and then the exhaust shutter valve 25 is closed in a low load low-rotation range, and thereby exhaust gas at comparatively high pressure secured in the first exhaust port 5 is introduced to the mixture supply port 7 during the term of deviation of the exhaust valve opening timing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply device for an engine, which is provided with a mixture supply port which mixes pressurized air and fuel and supplies them to a combustion chamber separately from an intake port.

[0002]

2. Description of the Related Art Conventionally, as disclosed in, for example, Japanese Utility Model Laid-Open No. 62-18335, a third intake port for supplying air-fuel mixture is provided in addition to first and second intake ports for supplying air to a combustion chamber. It is opened in the combustion chamber, an injector for fuel injection is provided in this port, and this port is connected to a communication passage equipped with a supercharger for supplying pressurized air, and the opening of this port to the combustion chamber is fixed. A timing valve (third intake valve) that opens and closes at a timing is provided, and the valve opening timing is set to the first and second
There is known a fuel supply device that is set to be later than the opening timing of the intake valve of the intake port. According to this device, the fuel and the pressurized air are mixed in the third intake port, and the mixture is burned in the latter half of the intake stroke, separately from the air taken in from the first intake port and the like. Sent to the room. Then, in the low load region, while the second intake port is closed, the swirl is generated in the combustion chamber by the intake air from the first intake port, and the mixture is supplied from the third intake port for supplying the mixture to the combustion chamber. By sending it toward the spark plug in the central portion, it becomes possible to achieve a stratified state in which the air-fuel mixture is unevenly distributed around the spark plug, and lean burn due to stratified combustion improves fuel efficiency.

[0003]

In this type of device, pressurized air is supplied to the air-fuel mixture supply port in order to promote mixing and atomization of fuel in the air-fuel mixture supply port,
A device for supplying the pressurized air is required. And
In particular, in order to achieve lean burn by stratified combustion, it is required to supply the compressed air to the air-fuel mixture supply port in the operation region on the low load and low rotation side. However, if, for example, a turbocharger is used as a device for supplying compressed air, it is difficult to obtain sufficient compressed air in the operating region on the low load and low rotation side, and a compressor or electric type driven by the engine output shaft is used. However, even if the lean burn is achieved, there is room for improvement such as energy loss due to driving of the above device.

In view of the above circumstances, the present invention can supply exhaust gas as a pressurized gas to the air-fuel mixture supply port, and can supply relatively high-pressure gas even in an operating region on the low load and low rotation side. By doing so, fuel mixing and atomization are promoted, and the effect of improving fuel efficiency is enhanced,
It is also an object of the present invention to provide an engine fuel supply device that can also improve emissions.

[0005]

In order to achieve the above object, the present invention provides an air-fuel mixture supply port which is provided with an injector for fuel supply and which is supplied with a pressurized gas, and an intake port. In the fuel supply device for an engine, which is provided separately from the above, and a timing valve that opens later than the intake valve of the intake port is provided in the opening of the mixture supply port to the combustion chamber, Exhaust ports are provided so that the exhaust valve opening timing of some of these exhaust ports is earlier than the exhaust valve opening timing of other exhaust ports. An exhaust shutter valve that is closed and opened at least in the high load and high rotation range is provided, and a communication passage that connects the exhaust port upstream of the exhaust shutter valve and the mixture supply port is also provided. It is.

In this structure, in a certain operating range,
The opening degree of the exhaust shutter valve may be gradually increased as the operating state changes to the high load / high speed side.

[0007]

According to the present invention, exhaust gas is supplied from the exhaust port provided with the exhaust shutter valve to the air-fuel mixture supply port through the communication passage at least in the low load and low rotation range. In this case, since the exhaust shutter valve is closed and the exhaust valve closing timing is set as described above, relatively high-pressure exhaust gas is obtained, and lean burn is performed in this operating region. As a result, a relatively large amount of oxygen is contained in the exhaust gas, which is suitable for producing the air-fuel mixture at the air-fuel mixture supply port.

[0008]

Embodiments of the present invention will be described with reference to the drawings.
1 and 2 show a fuel supply device according to an embodiment of the present invention. In these figures, each cylinder 1 of the engine is provided with a combustion chamber 2 whose volume changes with the operation of a piston (not shown), and at least one intake port and a plurality of exhaust ports are provided for this combustion chamber 2. A mixture gas supply port is provided, and in the illustrated example, the downstream end is the combustion chamber 2
Two intake ports 3 and 4 that open to one half of the combustion chamber 2, two exhaust ports 5 and 6 whose upstream ends open to the other half of the combustion chamber 2, and a downstream end near the center of the combustion chamber. The air-fuel mixture supply port 7 opening to the. These port 3
7 to 7 are formed on the cylinder head. Further, the spark plug 8 is provided in the combustion chamber 2 at a position relatively close to the opening of the air-fuel mixture supply port 7.

Intake valves 11 and 12 are provided at the openings of the intake ports 3 and 4 to the combustion chamber 2, and exhaust valves 13 and 14 are provided at the openings of the exhaust ports 5 and 6 to the combustion chamber 2. Are provided, and the intake valves 11 and 12 and the exhaust valve 1 are provided.
The valves 3 and 14 are operated by a valve mechanism (not shown) including a camshaft and the like. Further, a timing valve 15 is provided at the opening of the mixture supply port 7 to the combustion chamber 2, and the timing valve 15 is, for example, a valve operating mechanism such as a cam shaft similar to a valve operating mechanism for intake / exhaust valves. It is operated by a mechanism to open and close at a predetermined timing described later.

Air is introduced into the intake ports 3 and 4 through the intake passage 16. The intake passage 16 includes a common intake passage 16a on the upstream side and a surge tank 16 on the downstream side.
b and an independent intake passage 16c formed downstream thereof and connected to the intake ports 3 and 4 of each cylinder 1. The common intake passage 16a operates in response to an accelerator operation to adjust the intake air amount. A throttle valve 17 is provided.

An injector 20 for fuel supply is provided upstream of the timing valve 15 in the air-fuel mixture supply port 7. Further, a throttle valve 21 is provided in the air-fuel mixture supply port 7 upstream of the injector 20, and the throttle valve 21 is actuated by an actuator 22 to change the opening degree. In addition, an auxiliary injector 23 is provided in the intake passage 16 in the vicinity of a collecting portion on the upstream side of the independent intake passage 16c, and in the region of the high load side or the high rotation side, the auxiliary injector 23 is provided in addition to the injector 20 of the mixture supply port 7. Fuel is also supplied from the injector 23.

Exhaust gas is introduced into the mixture gas supply port 7 as a pressurized gas for mixing with fuel. As a structure for guiding the exhaust gas, an exhaust shutter valve is provided on one of the exhaust ports 5 and 6 (this exhaust port is called the first exhaust port 5 and the other exhaust port is called the second exhaust port 6 in the embodiment). 25, and a communication passage 2 that connects the first exhaust port 5 upstream of the exhaust shutter valve 25 and the mixture supply port 7 to each other.
7 is provided.

The exhaust shutter valve 25 is operated by an actuator 26 in response to a control signal. Further, the communication passage 27 is provided with a one-way valve 28 for preventing backflow of the exhaust gas to the exhaust port 5, and a chamber 29 for storing the pressurized exhaust gas.

Reference numeral 30 denotes a control unit (ECU) composed of a microcomputer, etc., and includes a rotation speed sensor 31 for detecting an engine rotation speed, and an engine load sensor 32 for locking an engine load equivalent amount such as an axial torque of the engine.
The signals from the actuators 22 and 26 are received.
A control signal is output to control the throttle valve 21 and the exhaust shutter valve 25 according to the operating state.
Furthermore, the above-mentioned injectors 20 and 23 are also controlled.

FIG. 3 shows opening / closing timings of the intake / exhaust valves 11-14 and the timing valve 15.
1 and 12 are opened from near the top dead center to a little later than the bottom dead center. On the other hand, the timing valve 15 is set such that its opening timing and closing timing are later than those of the intake valves 11 and 12, respectively, and the timing valve 15 is opened within a range from the latter half of the intake stroke to the compression stroke. Also, both exhaust ports 5, 6
The exhaust valves 13 and 14 of the first exhaust valve 13 and 14 are opened in the exhaust stroke, but the opening timings of the two are shifted, and the opening timing of the first exhaust valve (exhaust valve of the first exhaust port 5) 13 is the second exhaust valve (second exhaust valve). Port 6
Exhaust valve) 14 is opened earlier than the opening time.

FIG. 4 shows the characteristics of the operation of the exhaust shutter valve 25 and the throttle valve 21 of the air-fuel mixture supply port 7 according to the operating state. The exhaust shutter valve 25 is fully closed at least in the low load low rotation range or closed to a minute opening degree by the control according to the operating state by the ECU 30, and is opened at least in the high load high rotation range. For example, the line La corresponding to the predetermined intake air amount in this figure is closed on the low load / low rotation side and opened on the high load / high rotation side. Further, the throttle valve 21 is closed to a minimum opening in a predetermined region near the idle operation region where the intake air amount is particularly small among the regions on the low load and low rotation side from the line La, and the intake air amount increasing direction (high load) It is gradually opened as the operating state shifts to the high rotation side), and is fully opened on the high load side from the line La.

Next, the operation of the apparatus of this embodiment will be described.

At least at low load and low rotation, the first
Since the exhaust shutter valve 25 of the exhaust port 5 is closed and the opening / closing timings of both the exhaust valves 13 and 14 are set in advance as shown in FIG. 3, the first exhaust port 5 upstream of the exhaust shutter valve 25 The pressure of the exhaust gas inside is increased. That is, the opening timing of the first exhaust valve 13 is the second
Since the exhaust valve 14 is opened earlier, the high pressure gas after combustion is sent out only to the first exhaust port 5 from the time the first exhaust valve 13 is opened to the time the second exhaust valve 14 is opened, and
By the exhaust shutter valve 25 blocking or restricting exhaust outflow to the downstream side of the first exhaust port 5,
Exhaust shutter valve 2 despite the low exhaust flow rate
5 The pressure in the first exhaust port 5 upstream 5 is sufficiently increased.

This relatively high pressure exhaust gas is introduced to the mixture supply port 7 via the one-way valve 28 and the chamber 29. Then, the gas flow rate is adjusted by controlling the opening degree of the throttle valve 21 provided in the air-fuel mixture supply port 7 in accordance with the operating state, and this gas and the fuel injected from the injector 20 are mixed, By sending the air-fuel mixture to the vicinity of the spark plug 8 in the combustion chamber 2, stratified charge combustion is performed.

In this case, the relatively high-pressure exhaust gas is applied, which is advantageous for mixing and atomization, and in addition, the effect of promoting the atomization and vaporization of the fuel by the heat of the exhaust gas is obtained. Further, in this low load and low rotation speed range, lean burn is performed, so that the oxygen concentration in the exhaust gas is relatively high, and therefore it is possible to sufficiently contain oxygen in the air-fuel mixture. Due to these factors, an air-fuel mixture having excellent combustibility is generated.

Further, the exhaust gas supplied to the air-fuel mixture supply port 7 is sent to the combustion chamber 2 to obtain the function as EGR, so that NOx is also reduced.

On the other hand, if the exhaust shutter valve 25 is kept closed in the operating region on the high load / high rotation side, the exhaust pressure becomes abnormally high, which adversely affects the operation of the engine. Therefore, output performance is required rather than lean burn. Therefore, at least in the high load and high rotation range,
By opening the exhaust shutter valve 25, an increase in exhaust pressure is avoided, the throttle valve 21 of the mixture supply port 7 is opened, and the auxiliary injector 2 of the intake passage 16 is opened.
Fuel is also supplied from 3, and uniform combustion is performed with the fuel dispersed throughout the combustion chamber 2.

In the above-described embodiment, the exhaust shutter valve 25 is switched between the closed state and the open state with the solid line La in FIG. 4 as a boundary, but for example, the dashed line Lb in FIG. In a certain operating range from the degree of the solid line La to the degree of the solid line La, the exhaust shutter valve 25 may be linearly controlled so that the opening degree of the exhaust shutter valve 25 gradually increases as the operating state changes to the high load and high rotation side. Good. In this way, the exhaust pressure acting on the combustion chamber 2 and the exhaust gas pressure supplied to the air-fuel mixture supply port 7 are appropriately adjusted according to the operating state, and abrupt changes in exhaust pressure are avoided.

Further, in the illustrated embodiment, as a passage structure for guiding the exhaust gas from the first exhaust port 5 to the air-fuel mixture supply port 7, the air-fuel mixture supply port 7 and the first exhaust port 5 of the same cylinder are connected. Although it is connected by 27, the air-fuel mixture supply port 7 may be connected to the first exhaust port 5 of another cylinder.

[0025]

According to the apparatus of the present invention, as a structure for supplying the pressurized gas to the mixture supply port, the exhaust valve opening timing of some of the plurality of exhaust ports and the other exhaust ports are set. The exhaust shutter valve is closed earlier than the opening timing of the exhaust valve, and an exhaust shutter valve that closes at least in the low load and low rotation range is provided in the middle of this exhaust port, and the exhaust port upstream of the exhaust shutter valve and the mixture gas supply port The exhaust gas is used as a gas for forming the air-fuel mixture, and the exhaust gas having a relatively high pressure can be supplied even in a region where the exhaust flow rate is small. Therefore, a pressurizing means such as a pump is not required, and energy loss is reduced,
Achieves lean burn effectively, can significantly reduce fuel consumption, and uses exhaust gas to reduce NO
It is also effective in reducing emissions by reducing x. Further, by opening the exhaust shutter valve at least in the high load and high rotation range, it is possible to prevent the exhaust pressure from rising excessively.

In the present invention, the opening degree of the exhaust shutter valve is gradually increased as the operating state changes to the high load / high speed side in a certain operating range.
It is possible to appropriately adjust the pressure of the gas supplied to the air-fuel mixture supply port according to the operating state, to favorably operate the engine and generate the air-fuel mixture, and to prevent a shock or the like due to a sudden change in exhaust pressure.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of a fuel supply device according to a first embodiment of the present invention.

FIG. 2 is an overall schematic view of the fuel supply device.

FIG. 3 is a diagram showing opening / closing timings of intake / exhaust valves and a timing valve.

FIG. 4 is a diagram showing a map of a throttle valve opening degree according to an operating state.

[Explanation of symbols]

 2 Combustion chamber 3,4 Intake port 5,6 Exhaust port 7 Mixture supply port 13,14 Exhaust valve 15 Timing valve 20 Injector 25 Exhaust shutter valve 27 Communication passage

Claims (2)

[Claims] 1. An air-fuel mixture supply port, which comprises an injector for supplying fuel and is adapted to supply pressurized gas, is provided separately from an intake port, and the air-fuel mixture supply port is connected to a combustion chamber. In an engine fuel supply device with a timing valve that opens later than the intake valve of the intake port in the opening, multiple independent exhaust ports that open into the combustion chamber are provided, and the exhaust valves of some of these exhaust ports The opening timing is set earlier than the opening timing of the exhaust valves of other exhaust ports, and an exhaust shutter valve that closes at least in the low load low rotation range and opens at least in the high load high rotation range is provided in the middle of some of these exhaust ports. A fuel supply device for an engine, comprising: a communication passage that connects an exhaust port upstream of the exhaust shutter valve and the mixture supply port. 2. The fuel for an engine according to claim 1, further comprising opening degree adjusting means for gradually increasing the opening degree of the exhaust shutter valve in accordance with a change in the operating state toward the high load and high rotation side in a certain operating range. Supply device.